IPAC2018 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
MOYGB1	Status and Future Strategy for Advanced High Power Microwave Sources for Accelerators	klystron, electron, operation, linac	12
	F. Gerigk CERN, Geneva, Switzerland
	The need for more energy efficient high power microwave devices for accelerator applications continues to increase. This is important for development of cost effective accelerator designs that are coming up in the near future. Efforts are already in place to design new devices that could stretch the limits of RF power conversion to the highest levels possible. Devices including new technologies and design innovations like multi beam, increased number of cavities designs are being considered. Advances in the application of solid state amplifiers to accelerators are also being realized. This invited talk will cover the recent advances and status of such efforts. It will discuss future needs and a strategy for pursuing these efforts on a faster time scale for the benefit of the accelerator community.
	Slides MOYGB1 [11.575 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOYGB1
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYGB2	The LCLS-II: A High Power Upgrade to the LCLS	linac, undulator, cryomodule, electron	18
	J.N. Galayda SLAC, Menlo Park, California, USA
	Funding: The work is supported by DOE under grant No. DE-AC02-76SF00515 The LCLS-II is an upgrade of the LCLS X-ray FEL based on a 4 GeV superconducting RF linac. The LCLS-II is designed to produce 100's of Watts of X-rays from 200 eV up to 5 keV. The linac uses 1.3 GHz 9-cell cavities processed using the N2-doping technique and will be the first large scale CW SCRF linac with a Q of roughly 3x10¹⁰ at a gradient of 16 MV/m. The injector which will be commissioned in spring 2018, is based on the normal conducting CW RF APEX gun developed at LBNL. The LCLS-II will have two undulators: the soft X-ray undulator is a 39 mm period hybrid PM with an adjustable vertical gap to cover the range from 200 eV to 1.5 keV and hard X-ray undulator is a novel adjustable horizontal gap hybrid PM undulator with 26 mm period to generate vertically polarized X-rays from 1 to 5 keV. The talk will review the performance goals as well as the hardware fabrication.
	Slides MOYGB2 [11.367 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOYGB2
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOZGBD3	Performance of the First LCLS-II Cryomodules: Issues and Solutions	cryomodule, HOM, radiation, operation	34
	N. Solyak, E. Cullerton, J. Einstein-Curtis, E.R. Harms, B.D. Hartsell, J.P. Holzbauer, T.N. Khabiboulline, A. Lunin, Y.M. Pischalnikov, R.P. Stanek, G. Wu Fermilab, Batavia, Illinois, USA O. Napoly CEA/DSM/IRFU, France
	LCLS-II 4 GeV linac is on the middle production stage. Linac contains 40 cryomodules of 1.3 GHz and 3 cryomodules of 3.9 GHz, including spares. Fermilab and JLAB share responsibility for cryomodule design, assembly and test. Paper will overview the performance of the cryomodules it the tests, lessons learned and modifications in design to improve performance.
	Slides MOZGBD3 [8.630 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBD3
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOZGBF2	Status of the FAIR Project	proton, antiproton, target, dipole	63
	P.J. Spiller, M. Bai, O. Boine-Frankenheim, A. Dolinskyy, F. Hagenbuck, C.M. Kleffner, K. Knie, S. Menke, C. Omet, A. Schuhmann, H. Simon, M. Winkler GSI, Darmstadt, Germany J. Blaurock, M. Ossendorf FAIR, Darmstadt, Germany I. Koop BINP SB RAS, Novosibirsk, Russia D. Prasuhn, R. Tölle FZJ, Jülich, Germany
	The realization of the new Facility for Antiproton and Ion Research, FAIR at GSI, Germany, has advanced significantly. The civil construction process of the Northern part of the building complex, including the excavation of the SIS100 synchrotron tunnel has been launched end of 2017. On site of the GSI campus, major preparations and upgrade measures for the injector operation of the existing accelerator facilities are ongoing and will be completed mid of 2018. The shielding of the SIS18 accelerator tunnel has been enhanced for the booster operation at high repetition rates and high intensity Proton beams. Two new transformer stations were set-up and commissioned which will provide the required pulse and common power for FAIR. All major contracts for series production of SIS100 components have been signed and a large number of the superconducting SIS100 magnets has been produced and accepted. Major testing infrastructures for superconducting magnets of SIS100 and Super-FRS have been set-up at JINR, CERN and GSI. Also for all other FAIR accelerator systems, the procurement of the components is progressing well
	Slides MOZGBF2 [4.266 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF2
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOZGBF4	Evolution of the Superconducting Linac Output Energy at the Spallation Neutron Source	cryomodule, operation, linac, SRF	73
	S.-H. Kim, D.E. Anderson, M.T. Crofford, M. Doleans, J. Galambos, S.W. Gold, M.P. Howell, M.A. Plum, D.J. Vandygriff ORNL, Oak Ridge, Tennessee, USA R. Afanador, D.L. Barnhart, B. DeGraff, J.D. Mammosser, C.J. McMahan, T.S. Neustadt, C.C. Peters, J. Saunders, D.M. Vandygriff ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. The SNS linac output energy has increased since the start of neutron production in FY2007. The various improvements that contributed to the increase of the linac output energy are LLRF/control system improvement, high voltage converter modulator system improvement, high-power RF system improvement, cryomodule repairs, spare cryomodule development and accelerating gradient improvement through in-situ plasma processing. In this paper, the history of the SNS SCL output energy is reported, and plans for the near-term future and for the Proton Power Upgrade (PPU) project are also presented.
	Slides MOZGBF4 [34.185 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF4
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF012	Study of Crabbed Collision in eRHIC With a Combination of Strong-Strong and Weak-Strong Simulations	simulation, electron, proton, luminosity	105
	Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, Y. Hao, C. Montag, V. Ptitsyn, V.V. Smaluk, F.J. Willeke BNL, Upton, Long Island, New York, USA J. Qiang LBNL, Berkeley, California, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In the present design of the future electron-ion collider eRHIC at the Brookhaven National Laboratory, a crossing angle of 22~mrad between the electron and proton orbits at the interaction region is adopted. To compensate the geometric luminosity loss, a local compensation scheme with two sets of crab cavities for each beam is considered. In this article, we first carry out strong-strong beam-beam simulation to study possible coherent beam-beam instability. Under the assumption of no coherent beam-beam motion, we then carry out a weak-strong beam-beam simulation to determine the long-term stability of the proton beam with the equilibrium electron beam sizes extracted from the strong-strong beam-beam simulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF020	Higher Order Mode Coupling Options for the eRHIC Crab Cavity	HOM, damping, coupling, impedance	121
	Q. Wu, I. Ben-Zvi, S. Verdú-Andrés, B. P. Xiao BNL, Upton, Long Island, New York, USA I. Ben-Zvi Stony Brook University, Stony Brook, USA
	Funding: This work was supported by the US Department of Energy via Brookhaven Science Associates LLC under contract no. DE-SC0012704. The eRHIC crab cavity adopts the double quarter wave structure developed at Brookhaven National Lab for the LHC Hi-Lumi upgrade crab cavities. The cavity's fundamental mode is at 338 MHz with the first higher order mode more than 180 MHz above that. We looked into the higher order mode distribution up to 2 GHz, and considered various locations and geometries of the coupling scheme. The cylindrical outer shell of the cavity allowed various possibilities for coupler port openings on all the walls, which were difficult for the narrow waist of the LHC double quarter wave crab cavities. Beam pipe absorbers are also options for simpler high frequency modes damping. Some preliminary high pass filter design will also be discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF020
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF022	Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities	luminosity, simulation, proton, LLRF	129
	E. Yamakawa, R. Apsimon, A.C. Dexter Cockcroft Institute, Lancaster University, Lancaster, United Kingdom P. Baudrenghien, R. Calaga, F.J. Galindo Guarch CERN, Geneva, Switzerland
	The High-Luminosity LHC (HL-LHC) crab cavities (CCs) will be installed on both sides of IP1 (ATLAS) and IP5 (CMS) to compensate for the geometric luminosity reduction due to the crossing angle. To cope with the increased beam current (0.55 A DC for LHC, 1.1 A for HL-LHC), the operation of the LLRF system has been changed: rather than fully compensating the transient beam loading, we allow the phase to vary along the turn (100 ps peak-peak with 1.1 A DC). This has been implemented at LHC since July 2017. The CCs have high loaded Q (5e5) and the available RF power is insufficient to follow the bunch phase modulation. The crabbing voltage is not modulated, causing a phase error w.r.t. the individual bunch centroids, leading to transverse kicks of the centroids and an asymmetric crabbing of the bunch cores. We present an analytical model for the resulting luminosity reduction and validate with particle tracking simulations. Due to the symmetry of the bunch filling patterns for the counter-rotating beams, the peak luminosity is reduced by only 2% for nominal HL-LHC parameters at IPs 1 and 5, which is within tolerable limits.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF022
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF034	Layout and Performance of the FCC-ee Pre-Injector Chain	linac, emittance, damping, injection	169
	S. Ogur, T.K. Charles, K. Oide, Y. Papaphilippou, L. Rinolfi, F. Zimmermann CERN, Geneva, Switzerland A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov BINP SB RAS, Novosibirsk, Russia I. Chaikovska, R. Chehab LAL, Orsay, France K. Furukawa, N. Iida, T. Kamitani, F. Miyahara KEK, Ibaraki, Japan E.V. Ozcan Bogazici University, Bebek / Istanbul, Turkey S.M. Polozov MEPhI, Moscow, Russia
	The Future Circular e⁺e⁻ Collider pre-injector chain consists of a 6 GeV S-Band linac, a damping ring at 1.54 GeV and pre-booster ring to reach 20 GeV for injection to the main booster. The electron and positron beams use the same accelerator chain alternatively. The e⁺ beam is generated from a novel low level RF-gun providing 6.5 nC charge at 11 MeV with 0.5 micron geometric emittance. The e⁺ beam is produced by the impact of a 4.46 GeV e^- beam onto a hybrid target, accelerated in the linac up to 1.54 GeV, and injected to the damping ring for emittance cooling. Simulations on the performance of the DR are presented for reaching the required equilibrium emittances at the required damping time. As an alternative option, a 20 GeV linac is considered utilising C-Band cavities and simulations studies have been undertaken regarding the beam transport and transmission efficiency up to that energy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF034
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF036	FCC-ee Hybrid RF Scheme	HOM, impedance, operation, radiation	173
	Sh. Gorgi Zadeh, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany R. Calaga, F. Gerigk CERN, Geneva, Switzerland
	Funding: Research supported by the FCC design study For FCC-ee, the range of beam energies and beam currents is large between each mode of operation, all scaled to an available 50 MW maximum power per beam. The two limiting scenarios for the RF system design are at low energy (45 GeV) with high beam current (1.45 A) and the highest energy (182.5 GeV) with a radiation loss reaching 8.92 GeV per turn. In this paper, RF staging with a hybrid scheme using both 400 MHz and 800 MHz is proposed to mitigate the requirements on the two extremes. Relevant comparisons are made with respect to using only a single frequency for all modes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF036
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF042	Crab Cavity Failures Combined with a Loss of the Beam-Beam Kick in the High Luminosity LHC	beam-losses, luminosity, dumping, collimation	192
	B. Lindstrom, H. Burkhardt, V.K.B. Olsen, A. Santamaría García, K.N. Sjobak, M. Valette, D. Wollmann CERN, Geneva, Switzerland
	Crab cavities are an essential component of the High Luminosity LHC (HL-LHC) project. In case of a failure they can create large transverse kicks on the beam within tens of microseconds and, therefore, require a fast extraction of the circulating beam. In this paper, the effects of different crab cavity failures in combination with the missing beam-beam kick following the dump of only one LHC beam are presented and consequences for the interlocking strategy of crab cavities are discussed. Work supported by the High Luminosity LHC project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF042
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF061	Emittance Growth in Coast in the SPS at CERN	emittance, scattering, experiment, feedback	257
	F. Antoniou, H. Bartosik, T. Bohl, R. Calaga, L.R. Carver, J. Repond, G. Vandoni CERN, Geneva, Switzerland A. Alekou UMAN, Manchester, United Kingdom
	Funding: Research supported by the HL-LHC project. The HL-LHC prototype crab-cavities are installed in the CERN SPS, which will allow for a comprehensive beam test with high energy protons for the first time. As the time available for experimental beam dynamics studies with the crab cavities installed in the machine will be limited, a very good preparation is required. One of the main concerns is the induced emittance growth, driven by phase amplitude jitter in the crab cavities. In this respect, several machine development (MD) studies were performed during the past years to quantify and characterize the long term emittance evolution of proton beams in the SPS. In these proceedings, the experimental observations from past years are summarized and the MD studies from 2016 and 2017 are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF061
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF076	Energy Spread Compensation in Arbitrary Format Multi-Bunch Acceleration With Standing Wave and Traveling Wave Accelerators	beam-loading, acceleration, positron, linac	307
	M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan
	In the E-driven ILC (International Linear Collider) positron source, the beam is generated and accelerated in a multi-bunch format with mini-trains. The macro-pulse contains 2 to 8 mini-trains with several train gaps, because the pulse format is a copy of a part of the bunch storage pattern in DR (Damping Ring). This pulse format causes a variation of the accelerator field in the pulse due to the transient beam loading and an intensity fluctuation of captured positron. In this article, we discuss the compensation of the energy spread of such beam in standing wave and traveling wave accelerators. For standing wave accelerator, it can be compensated by switching input RF at appropriate timings. For traveling wave accelerator, it can be compensated by amplitude modulation of the input RF.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF076
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF077	A Design Study of the Electron-driven ILC Positron Source Including Beam Loading Effect	positron, beam-loading, acceleration, booster	311
	H. Nagoshi, M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan K. Negishi Iwate University, Morioka, Iwate, Japan T. Omori, M. Satoh, Y. Seimiya, J. Urakawa KEK, Ibaraki, Japan Y. Sumitomo LEBRA, Funabashi, Japan T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
	The International Linear Collider (ILC) is a next-generation accelerator for high-energy physics to study the Higgs and top sector in the Standard Model, and new physics such as supersymmetry and dark matter. ILC positron source based on Electron-driven method has been proposed as a reliable technical backup. In this article, we report the design study of the positron source based on the off-the-shelf RF components. The positron is generated and accelerated in a multi-bunch format. To compensate the energy variation by the transient beam loading effect, we employ AM (Amplitude Modulation) technique and the results were 16.60 ± 0.14 MV (peak-to-peak) for L-band 2m cavity driven by 22.5 MW power and 25.76 ± 0.19 MV (peak-to-peak) for S-band 2m ac-celerator driven by 36 MW power with 0.78 A beam load-ing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF077
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK001	Optics for RF Acceleration Section for the High Energy Large Hadron Collider	optics, quadrupole, dipole, instrumentation	345
	L. van Riesen-Haupt, J.L. Abelleira University of Oxford, Oxford, United Kingdom J.L. Abelleira, E. Cruz Alaniz, P. Martinez Mirave, A. Seryi JAI, Oxford, United Kingdom M. Hofer, F. Zimmermann CERN, Geneva, Switzerland D. Zhou KEK, Ibaraki, Japan
	Funding: Work supported by the Horizon 2020 project EuroCirCol, grant 654305 and by the Science and Technology Facilities Council As part of the FCC study, the design of the High Energy LHC (HE-LHC) is addressed. A proposed layout for the interaction region for the containing the radio frequency (RF) cavities and various beam instrumentation will be discussed. The higher energy requires more RF cavities, which strongly restricts the space available for optics and instrumentation. Another challenge arises because the beam rigidity increases whilst the LHC geometry has to be conserved. To this end, next generation dipoles have to be used in order to achieve sufficient beam to beam separation. A design that provides enough beam stay clear (BSC) in all the magnets will be presented. The design introduces an additional quadrupole on either side of the RF region to be used for phase advance adjustments that can increase the dynamic aperture.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK001
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK005	HE-LHC Final Focus: Flat Beam Parameters and Energy Deposition Studies	optics, luminosity, quadrupole, dipole	356
	J.L. Abelleira, E. Cruz Alaniz, A. Seryi, L. van Riesen-Haupt JAI, Oxford, United Kingdom J.L. Abelleira, E. Cruz Alaniz, L. van Riesen-Haupt University of Oxford, Oxford, United Kingdom
	Funding: Work supported by EuroCircol, EU's Horizon 2020 grant No 654305 & STFC grant to the John Adams Institute The High Energy LHC (HE-LHC) project is studying the feasibility of a new proton-proton collider with a beam energy of 13.5 TeV. The nominal optics features a β^* of 0.25 m and crab-cavities. Here we present a flat-beam optics that can be used with a non-zero crossing angle, in the absence of crab cavities. This is followed by energy deposition studies for the superconducting quadrupoles and dipole separators. The total dose in these magnets coming from the collision debris is evaluated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK005
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK010	Study Progress of the Coupling Resonance of the Crab Crossing Scheme in Electron-Ion Collider	luminosity, electron, synchrotron, simulation	368
	Y. Hao FRIB, East Lansing, USA Y. Luo, V. Ptitsyn BNL, Upton, Long Island, New York, USA J. Qiang LBNL, Berkeley, California, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Crab crossing scheme is essential collision scheme to achieve high luminosity for the future electron-ion collider (EIC). The bunch length effect of the ion beam cannot be ignored even when cooling is present compared with the wavelength of the crab cavity, therefore, the nonlinear dependence of the crabbing kick may present a challenge to the beam dynamics of the ion beam, hence an impact to the luminosity lifetime. In this paper, we present the result of numerical beam dynamics studies of the crab crossing scheme. The result indicates that there is a special coupling resonance in the nonlinear relation of the crab crossing scheme of the EIC, which dominates the luminosity degradation. And we will discuss the possible remedies for such resonance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK010
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK017	Transient Beam Loading Due to the Bunch Train Gap and Its Compensation Experiments at BEPC-II and ALS	experiment, feedback, beam-loading, luminosity	390
	H. Wang, R.A. Rimmer, S. Wang JLab, Newport News, Virginia, USA J.P. Dai, Q. Qin, J. Xing, J.H. Yue, Y. Zhang IHEP, Beijing, People's Republic of China D. Teytelman Dimtel, San Jose, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Non-uniform bunch fill patterns in storage rings, driven by the need to provide gaps for beam aborting and ion clearing cause a large beam loading change in the RF cavities. The induced turn-periodic transient in the cavity voltage modulates longitudinal beam properties along the train, such as synchronous position and bunch length. In the EIC design, due to the asymmetric bunch train structure between the electron and the ion beam, such modulation results in shifting collision point and leads to reduced luminosity. We have carried out the beam based experiments at BEPC-II and ALS using bunch-by-bunch diagnostic capabilities of the coupled-bunch feedback systems to study this transient effect. A modulated bunch filling pattern with higher charge density around the gap has been demonstrated to be effective in partially compensating this transient modulation. Details of the experimental setups and the data analysis will be presented to this conference.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK017
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML009	New High Luminosity LHC Baseline and Performance at Ultimate Energy	operation, luminosity, optics, emittance	408
	L.E. Medina Medrano Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico A. Apollonio, G. Arduini, O.S. Brüning, M. Giovannozzi, L.E. Medina Medrano, S. Papadopoulou, Y. Papaphilippou, S. Redaelli, R. Tomás CERN, Geneva, Switzerland
	Funding: Research supported by the HL-LHC project and the Beam project (CONACYT, Mexico). The LHC machine is envisioned to operate eventually at an ultimate beam energy of 7.5 TeV at the end of LHC Run 4, i.e. after commissioning of the HL-LHC systems, a stage falling into the High Luminosity LHC (HL-LHC) era. In this paper we review the latest baseline parameters and performance, and study the potential reach of the HL-LHC with pushed optics at the ultimate beam energy. Results in terms of integrated luminosity and effective pile-up density of both the nominal (5.0×10³⁴ cm^-2 s⁻¹) and ultimate (7.5×10³⁴ cm^-2 s⁻¹) levelling operations are discussed
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML009
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML015	Simulations and Measurements of the CCL Modules of the LIGHT Accelerator	coupling, linac, proton, GUI	429
	V. F. Khan, G. De Michele, S. Fanella, S. H. Gibson, Ye. Ivanisenko, C. Mellace, J.L. Navarro Quirante, C. Zannini AVO-ADAM, Meyrin, Switzerland M. Esposito, P. Gradassi CERN, Geneva, Switzerland
	A 230 MeV proton LINAC system for medical applications is being developed and commissioned for the LIGHT (Linac Image Guided Hadron Therapy) project by AVO-ADAM. The LINAC system consists of a 750 MHz RFQ (Radio frequency quadrupole) for the low energy proton acceleration, 2998 MHz SCDTL (Side Coupled Drift Tube Linacs) for the medium energy and 2998 MHz CCL (Coupled Cavity Linacs) for the high energy. In particular, the CCL accelerating modules are used in the energy range from 37.5 - 230 MeV. In this paper we discuss the 3D EM (electro-magnetic) simulation results and measurements of the CCL modules.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML015
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML017	Status and Development of the MYRRHA Injector	diagnostics, linac, MMI, rfq	432
	D. Mäder, H. Höltermann, D. Koser, B. Koubek, K. Kümpel, P. Müller, U. Ratzinger, M. Schwarz, W. Schweizer BEVATECH, Frankfurt, Germany C. Angulo, J. Belmans, D. Davin, W. De Cock, P. Della Faille, F. Doucet, A. Gatera, Pompon, F.F. Pompon, D. Vandeplassche Studiecentrum voor Kernenergie - Centre d'Étude de l'énergie Nucléaire (SCK•CEN), Mol, Belgium M. Busch, H. Hähnel, H. Podlech IAP, Frankfurt am Main, Germany
	The MYRRHA project aims at coupling a cw 600 MeV, 4 mA proton linac with a sub-critical reactor as the very first prototype nuclear reactor to be driven by a particle accelerator (ADS). Among several applications, MYRRHA main objective is to demonstrate the principle of partitioning and transmutation (P&T) as a viable solution to drastically reduce the radiotoxicity of long-life nuclear waste. For this purpose, the linac needs an unprecedented level of reliability in terms of allowable beam trips. The normal conducting injector delivers 16.6 MeV protons to the superconducting main linac. The first section of the injector (up to 5.9 MeV) consists of an ECR source, a 4-Rod-RFQ and a rebunching line followed by 7 individual CH-type cavities. This entire section will be set up and operated by SCK·CEN in Louvain-la-Neuve, Belgium, for ample performance and reliability testing. The first CH cavity has been sent for power tests to IAP Frankfurt, Germany. The most recent status of all cavities, couplers and the beam diagnostics of the MYRRHA injector is presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML017
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML034	Development Status of Superconducting RF Transmission Electron Microscope	acceleration, LLRF, gun, SRF	481
	N. Higashi, A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, F. Qiu, M. Yamamoto KEK, Ibaraki, Japan S. Yamashita University of Tokyo, Tokyo, Japan
	Now we are developing a new type of transmission electron microscope (TEM) employing the accelerator technologies. In place of a DC thermal gun generally used in conventional TEMs, we apply a photocathode gun and a special-shaped superconducting cavity, named two-mode cavity. The two-mode cavity has two resonant modes of TM010 (1.3 GHz) and TM020 (2.6 GHz). To superimpose these, we can suppress the increase of the energy spread, which is needed for the high-spatial-resolution TEMs. We have already developed some prototypes of the photocathode gun and two-mode cavity, and now in the middle of the performance tests. In this presentation, we will show the latest status of the development.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML034
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML043	High Gradient Performance of an S-Band Backward Traveling Wave Accelerating Structure for Medical Hadron Therapy Accelerators	linac, proton, radiation, accelerating-gradient	491
	A. Vnuchenko, C. Blanch Gutiérrez, D. Esperante Pereira IFIC, Valencia, Spain S. Benedetti, N. Catalán Lasheras, A. Grudiev, B. Koubek, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch CERN, Geneva, Switzerland A. Faus-Golfe LAL, Orsay, France T.G. Lucas, M. Volpi The University of Melbourne, Melbourne, Victoria, Australia S. Pitman Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	The high-gradient performance of an accelerating structure prototype for a medical proton linac is presented. The structure was designed and built using technology developed by the CLIC collaboration and the target application is the TULIP (Turning Linac for Proton therapy) proposal developed by the TERA foundation. The special feature of this design is to produce gradient of more than 50 MV /m in low-β accelerating structures (v/c=0.38). The structure was tested in an S-band test stand at CERN. During the tests, the structure reached over above 60 MV/m at 1.2 μs pulse length and breakdown rate of about 5x10^-6 bpp. The results presented include ultimate performance, long term behaviour and measurements that can guide future optimization.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML043
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML052	The Path to Compact, Efficient Solid-State Transistor-Driven Accelerators	electron, linac, impedance, simulation	520
	D.C. Nguyen, C.E. Buechler, G.E. Dale, R.L. Fleming, M.A. Holloway, J.W. Lewellen, D. Patrick LANL, Los Alamos, New Mexico, USA V.A. Dolgashev, E.N. Jongewaard, E.A. Nanni, J. Neilson, A.V. Sy, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: Research presented in this work is supported by (LANL) Laboratory Directed Research and Development 20170521ER and by (SLAC) Department of Energy contract DE-AC02-76SF00515. Small, lightweight, few-MeV electron accelerators that can operate with low-voltage power sources, e.g., solid-state transistors running on 50 VDC, instead of high-voltage klystrons, will provide a new tool to enhance existing applications of accelerators as well as to initiate new ones. Recent advances in gallium nitride (GaN) semiconductor technologies * have resulted in a new class of high-power RF solid-state devices called high-electron mobility transistors (HEMTs). These HEMTs are capable of generating a few hundred watts at S-, C- and X-bands at 10% duty factor. We have characterized a number of GaN HEMTs and verified they have suitable RF characteristics to power accelerator cavities *. We have measured energy gain as a function of RF power in a single low-beta C-band cavity. The HEMT powered RF accelerators will be compact and efficient, and they can operate off the low-voltage DC power buses or batteries. These all-solid-state accelerators are also more robust, less likely to fail, and are easier to maintain and operate. In this poster, we present the design of a low-beta, 5.1-GHz cavity and beam dynamics simulations showing continuous energy gain in a ten-cavity C-band prototype. See for example, http://www.wolfspeed.com/downloads/dl/file/id/463/product/174/cghv59350.pdf ** J.W. Lewellen et al., Proceedings of LINAC2016, Paper MO3A03
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML052
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUXGBF2	Higher-Order-Mode Effects in Tesla-Type Superconducting RF Cavities on Electron Beam Quality	HOM, FEL, electron, detector	612
	A.H. Lumpkin, N. Eddy, D.R. Edstrom, P.S. Prieto, J. Ruan, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA K. Bishofberger, B.E. Carlsten LANL, Los Alamos, New Mexico, USA O. Napoly CEA/DSM/IRFU, France
	Funding: Work at Fermilab supported by FRA, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Dept. of Energy. *Work at LANL supported by U.S. Dept. of Energy through the LANL/LDRD Program. We report the direct observations of the correlation of higher order modes (HOMs) generated by off-axis electron beam steering in TESLA-type SCRF cavities and sub-macropulse beam centroid shifts (with the concomitant effect on averaged beam size and emittance). The experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility using its unique configuration of a PC rf gun injecting beam into two separated 9-cell cavities in series with corrector magnets and beam position monitors (BPMs) located before, between, and after them. The ~100-kHz oscillations with up to 300-μm amplitudes at downstream locations were observed in a 3-MHz micropulse repetition rate beam with charges of 500 and 1000 pC/b, although the effects were much reduced at 100 pC/b. The studies were based on HOM detector circuitry targeting the first and second dipole passbands, rf BPM bunch-by-bunch data, and imaging cameras viewing multi-slit images for emittance assessments at 33 MeV. Initial calculations reproduced a key feature of the phenomena. In principle, these results may be scaled to cryomodule configurations of major accelerator facilities.
	Slides TUXGBF2 [3.631 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBF2
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUYGBF4	Design and Simulation Tools for the High-Intensity Industrial Rhodotron Electron Accelerator	dipole, gun, electron, cathode	651
	W.J.G.M. Kleeven, M. Abs, J. Brison, E. Forton, J. M. Hubert, J. Walle IBA, Louvain-la-Neuve, Belgium
	The Rhodotron is a compact industrial CW recirculating electron accelerator producing intense beams with energies in the range from about 1 to 10 MeV. RF-frequencies are in the range of 100 to 400 MHz. Average beam powers can range from 10 kW to almost 1 MW, depending of the specific type of Rhodotron. Main industrial applications are polymer cross-linking, sterilization, food treatment and container security scanning. Recently, RF pulsing was developed to reduce the average wall power dissipation, thus reducing drastically the energy consumption. Pulsing also permits smaller cavities and higher energies up to 40 MeV, opening the way to applications such as mobile irradiators, or isotopes production by photonuclear reactions, thus offering a compact and high beam duty alternative to linacs. This paper concentrates on some crucial design tools and methods for transverse and longitudinal optics studies, particle tracking with space charge, beam formation studies in the electron gun and dipole magnet design.
	Slides TUYGBF4 [11.952 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBF4
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF001	Requirements for the Cryogenic Refrigerator and the He Distribution System for the MYRRHA 100 Mev Accelerator	linac, cryogenics, cryomodule, operation	655
	T. Junquera Accelerators and Cryogenic Systems, Orsay, France C. Angulo Studiecentrum voor Kernenergie - Centre d'Étude de l'énergie Nucléaire (SCK•CEN), Mol, Belgium D. Vandeplassche SCK•CEN, Mol, Belgium
	MYRRHA is an ADS demonstrator for the long-lived radioactive waste transmutation. It is composed of a High Energy CW Linac Accelerator (600 MeV - 4mA) coupled to a Subcritical Reactor of 100 MW thermal power. The main challenge of the Linac is a very high reliability performance to limit stress and long restart procedures of the reactor. Within the MYRRHA project phased approach for the construction, a 100 MeV-4 mA Linac (Injector up to 17 MeV and SC Linac between 17 MeV and 100 MeV) will be constructed in the Phase 1, covering 2016-2024. The SC Linac is composed of 58 Single-Spoke SC cavities, housed in 29 cryomodules. The cavities operates at 352 MHz, in a superfluid Helium bath at 2K. In this paper, the requirements for the Linac Cryogenic System are presented. The analysis of high thermal loads induced by the CW mode operation of cavities, leads to a Cryogenic Refrigerator with a power of 2700 W (equiv. power capacity at 4.5 K). Each cryomodule is connected through a dedicated Valve Box to the Helium transfer line running along the Linac tunnel. A description of the cryogenic system features and initial models of the tunnel and associated buildings are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF001
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF003	Integrated Prototyping in View of the 100 MeV Linac for Myrrha Phase 1	linac, cryomodule, controls, target	661
	D. Vandeplassche, J. Belmans SCK•CEN, Mol, Belgium C. Angulo, D. Davin, W. De Cock, P. Della Faille, F. Doucet, A. Gatera, Pompon, F.F. Pompon Studiecentrum voor Kernenergie - Centre d'Étude de l'énergie Nucléaire (SCK•CEN), Mol, Belgium D. Bondoux, F. Bouly LPSC, Grenoble Cedex, France H. Höltermann, D. Mäder BEVATECH, Frankfurt, Germany C. Joly, G. Olry, H. Saugnac IPN, Orsay, France M. Loiselet, N. Postiau, L. Standaert UCL, Louvain-la-Neuve, Belgium H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany
	Funding: Work partially supported by the European Commission H2020 programme MYRTE #662186 The MYRRHA project borne by SCK•CEN, the Belgian Nuclear Research Centre, aims at realizing a pre-industrial Accelerator Driven System (ADS) for exploring the transmutation of long lived nuclear waste. The linac for this ADS will be a High Power Proton Accelerator delivering 2.4 MW CW beam at 600 MeV. It has to satisfy stringent requirements for reliability and availability: a beam-MTBF of 250h is targeted. The reliability goal is pursued through a phased approach. During Phase 1, expected till 2024, the MYRRHA linac up to 100 MeV will be constructed. It will allow to evaluate the reliability potential of the 600 MeV linac. It will also feed a Proton Target Facility in which radioisotopes of interest will be collected through an ISOL system. This contribution will focus on the transition to integrated prototyping, which will emphasize (i) a test platform consisting of the initial section of the normal conducting injector (5.9 MeV), (ii) the realization of a complete cryomodule for the superconducting linac and of its cryogenic valve box. The cryomodule will house two 352 MHz single spoke cavities operated at 2K.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF003
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF011	Btrain Calibration with RF-Master Method	dipole, synchrotron, injection, pick-up	679
	L. Falbo, E. Bressi, M. Pezzetta, C. Priano CNAO Foundation, Milan, Italy
	CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. It is based on a synchrotron with a 77 m ring equipped with 16 normal conducting dipoles characterized by a long delay in the field stabilization. B-Train system is a fundamental device of the whole machine; it is used in feedback to the dipole power supply in order to regulate the magnetic field reducing the natural stabilization times that would cause long treatments. B-Train system allows to obtain the magnetic field starting from measurements of magnetic field changes: it works as an integrator and then it needs a system to reset the counts compensating the electronic and numerical drift of the system itself. An innovative method has been implemented at CNAO to reset Btrain counts exploiting beam measurements after the RF cavity trapping. This procedure has the advantage to avoid external and additional element like NMR probes. The paper shows the use of B-train system at CNAO and its calibration with this method, called "RF-master method".
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF011
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF012	Commissioning of the Lipac Medium Energy Beam Transport Line	vacuum, rfq, controls, operation	683
	I. Podadera, J. Castellanos, J.M. García, D. Gavela, A. Ibarra, D. Jiménez-Rey, A. Marqueta, L.M. Martinez Fresno, E. Molina Marinas, J. Mollá, P. Méndez, C. Oliver, D. Regidor, F. Toral, R. Varela, V. Villamayor, M. Weber, C. de la Morena CIEMAT, Madrid, Spain P. Cara, A. Marqueta, I. Moya Fusion for Energy, Garching, Germany T. Ebisawa, Y. Hirata, A. Ihara, Y. Ikeda, A. Kasugai, T. Kitano, K. Kondo, T. Narita, K. Sakamoto, T. Shinya, M. Sugimoto QST, Aomori, Japan D. Gex, A. Jokinen F4E, Germany J. Knaster IFMIF/EVEDA, Rokkasho, Japan M. Mendez Macias 7S, Peligros (Granada), Spain O. Nomen IREC, Sant Adria del Besos, Spain G. Pruneri Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy F. Scantamburlo INFN/LNL, Legnaro (PD), Italy
	Funding: This work has been funded by the Spanish Ministry of Economy and Competitiveness under the Agreement as published in BOE, 16/01/2013, page 1988 and the project FIS2013-40860-R. LIPAc* will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology to be used as neutron source of the IFMIF facility. Those facilities are essential for future fusion reactors material research. A 175 MHz RFQ will increase the energy up to 5 MeV before a Superconducting RF (SRF) linac with eight 175 MHz Half Wave Resonators brings the particles up to the final energy of 9 MeV. Between both stages, a Medium Energy Beam Transport line (MEBT)** aims at transporting and matching the beam between the RFQ and the SRF linac. The transverse focusing of the beam is controlled by five quadrupole magnets with integrated steerers, grouped in one triplet and one doublet. Two buncher cavities handle the longitudinal dynamics. Two movable scraper systems are included to purify the beam optics coming out the RFQ and avoid losses in the SRF linac. In this contribution, checkout of the beamline and its ancillaries in Japan is reported. Tests carried out on the beamline prior to the MEBT beam commissioning are described, focusing in vacuum tests, magnets powering, buncher conditioning and scrapers movement. * P. Cara et al., IPAC16, MOPOY057 , p.985, Busan, Korea (2016) ** I. Podadera et al., LINAC2016, TUPLR041, p.554, East Lansing, USA (2016).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF014	Beam Dynamics Studies For the IFMIF-DONES SRF-Linac	linac, SRF, cryomodule, solenoid	687
	L. Du, N. Bazin, N. Chauvin, S. Chel, J. Plouin CEA/IRFU, Gif-sur-Yvette, France
	The DONES (DEMO oriented neutron source) project is aimed at constructing a DEMO of IFMIF to provide sufficient material damage [1]. In the SRF-Linac of this project, losses can cause harmful material activation and must be maintained much less than 1W/m. It's a challenge to keep losses at such a low level with high beam power and high space charge. This paper presents two designs of the DONES SRF-Linac, one with 4 cryomodules and another with 5 cryomodules. The design details to reduce the losses and the multi-particle simulation results will be shown. The errors studies for these results will also be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF014
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF015	Preliminary Test Results of the First ESS Elliptical Cryomodule Demonstrator	cryomodule, cryogenics, vacuum, radiation	691
	F. Peauger, C. Arcambal, S. Berry, P. Bosland, E. Cenni, G. Devanz, T. Hamelin, O. Piquet, B. Renard, P. Sahuquet, T. Trublet CEA/DRF/IRFU, Gif-sur-Yvette, France C. Darve ESS, Lund, Sweden P. Michelato INFN/LASA, Segrate (MI), Italy G. Olivier IPN, Orsay, France J.P. Thermeau Laboratoire APC, Paris, France
	Two ESS elliptical cavities cryomodule prototypes are being developed and will be tested at CEA Saclay before starting the series production. This paper presents the preliminary test results of the first medium beta cavities cryomodule demonstrator M-ECCTD. The measurements of the cryogenic performances at 80 K and 2 K of the different cryomodule components and circuits are given. The first RF test results performed at low power are also reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF015
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF026	Higher-Harmonic RF System for Landau Damping in the CERN PS	damping, flattop, dipole, synchrotron	728
	H. Damerau, A. Lasheen, E.N. Shaposhnikova CERN, Geneva, Switzerland
	Longitudinal coupled-bunch instabilities after transition crossing and at the flat-top limit the intensity of LHC-type beams in the CERN Proton Synchrotron (PS). A dedicated coupled-bunch feedback for dipole oscillation modes, using a Finemet cavity as wide-band longitudinal kicker, suppresses the instabilities up to an intensity of about 2·10¹¹ particles per bunch at extraction. However, dipole and quadrupole coupled-bunch oscillations are observed beyond this intensity. At the flat-top they were damped with a 40 MHz RF cavity operated as a higher-harmonic RF system to increase Landau damping, in addition to the principal RF system at 10 MHz. The existing 40 MHz RF system, designed for RF manipulations at fixed frequency, does not cover the frequency range required during acceleration. It is therefore proposed to install a tunable RF system with a 5% relative frequency swing. This paper summarizes the observations of instability damping at the flat-top and presents preliminary parameters for the higher-harmonic RF system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF026
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF034	LEIR Injection Efficiency Studies as a Function of the Beam Energy Distribution from Linac3	linac, injection, bunching, optics	758
	S. Hirlaender, R. Alemany-Fernández, H. Bartosik, G. Bellodi, N. Biancacci, V. Kain, R. Scrivens CERN, Geneva, Switzerland
	High intensities in the CERN Low Energy Ion Ring (LEIR) are achieved using multi-turn injections from the pre-accelerator Linac3 combined with simultaneous stacking in momentum and transverse phase spaces. Up to seven consecutive 200 μs long, 200 ms spaced pulses are injected from Linac3 into LEIR by stacking each of them into the six-dimensional phase-space over 70 turns. An inclined septum magnet allows proper filling of the transverse phase-space plane, while longitudinal stacking requires momentum variation achieved by a shift of mean momentum over time provided by phase shifting a combination of 2 RF cavities at the exit of Linac3. The achievable maximum accumulated intensity depends strongly on the longitudinal beam quality of the injected beam. The longitudinal Schottky signal is used to measure the received energy distribution of the circulating beam which is then correlated with the obtained injection efficiency. This paper presents the experimental studies to understand and further improve the injection reliability and the longitudinal stacking.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF034
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF042	Characterization of the Beam Energy Spread at the REX/HIE-ISOLDE Linac	ISOL, linac, experiment, detector	787
	M.L. Lozano, N. Bidault, E. Fadakis, M.A. Fraser, E. Matli, J.A. Rodriguez CERN, Geneva, Switzerland
	ISOLDE is an on-line radioactive isotope separator located at CERN that works by colliding protons accelerated in the PS Booster into a fixed target and by separating the resultant ionized isotopes using a magnetic separator. The completion of the HIE-ISOLDE superconducting linac allows the acceleration of these ions to energy levels that were not reachable before, opening the door to new experiments in different fields. These experiments often have special requirements in terms of beam intensity and purity, transverse emittance or energy spread. A possible way to reduce the energy spread of the beam delivered to the experimental stations is to use one or more of the superconducting cavities as bunchers. The main results of several tests conducted during the last beam commissioning campaign prove that this mode of operation is feasible and will be presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF042
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF057	The SPS Tests of the HL-LHC Crab Cavities	cryomodule, vacuum, HOM, operation	846
	R. Calaga, O. Capatina, G. Vandoni CERN, Geneva, Switzerland
	Funding: Research supported by the HL-LHC project Two superconducting crab cavities in the framework of the High Luminosity (HL-LHC) LHC were built to test for the first time with proton beams in the Super Proton Synchrotron (SPS) at CERN. These tests will address the operation of the crab cavities in a high current and high intensity proton machine through the full energy cycle with a primary focus on cavity transparency, performance and stability, failures modes and long term effects on proton beams. An overview of the SPS cryomodule development towards the SPS tests along with the first test results are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF057
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF063	Beam Dynamics Studies of the ESS LINAC Using a New Multicell Cavity Model	linac, emittance, DTL, distributed	870
	R. De Prisco, D.C. Plostinar ESS, Lund, Sweden
	The European Spallation Source is designed to deliver 5 MW proton beam power on the target while keeping the beam induced losses below 1 W/m throughout the LINAC. This implies the need of accurate models to correctly describe the longitudinal beam dynamics within the multi-cell cavities. In all the previous error studies the cells of a multi-cell cavity were modelled as a sequence of independent gaps and the errors were applied directly on the amplitude of each cell accelerating field, considered as random variable. In this paper, instead, we present a new detailed analysis of the effect of the error tolerances on the beam dynamics including a new model to calculate the amplitude errors of the accelerating field in the multi-cell cavities: errors are applied on the geometrical parameters of each cavity; then the accelerating field is calculated solving the Maxwell equations over all the cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF063
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF068	Functional Integration of the RFQ in the ESS Systems	rfq, controls, LLRF, vacuum	890
	J.S. Schmidt, E. Bargalló, T. Fay, G. Hulla, B. Lagoguez, R. Montaño, E. Sargsyan, S. Scolari, H. Spoelstra ESS, Lund, Sweden A.C. Chauveau, M. Desmons, O. Piquet CEA/IRFU, Gif-sur-Yvette, France A.J. Johansson Lund University, Lund, Sweden W. Ledda Vitrociset s.p.a, Roma, Italy
	The 352 MHz Radio Frequency Quadrupole (RFQ) for the European Spallation Source ERIC (ESS) will be delivered during 2018. After delivery, installation and tuning of the cavity, the high power RF conditioning will be performed. At this point all the different systems that are needed to condition and operate the RFQ have to be in place and operational. This paper will give an overview of the system analysis that has been performed for the RFQ. The RFQ requirements for the RF system, including the RF distribution system (RFDS), the Low Level RF (LLRF) and the local RF protection system (RFLPS) will be presented. In addition, the paper covers the system integration of the structure in the ESS control and vacuum systems as well as the outcome of a machine protection analysis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF068
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF079	Scaled Alvarez-Cavity Model Investigations for the UNILAC Upgrade	DTL, simulation, alignment, pick-up	916
	M. Heilmann, X. Du, L. Groening, M. Kaiser, S. Mickat, M. Vossberg GSI, Darmstadt, Germany A. Seibel IAP, Frankfurt am Main, Germany
	The 1:3 scaled aluminum model of an Alvarez-type cavity with 10 gaps was used for comparison of simulation with measurement for the frequency and the electric field on axis. The scaled frequency is 325.224 MHz and an Alvarez cavity has a small frequency tuning range. With this scaled model it was possible to apply different stem configurations for each drift tube to damp parasitic modes and to increase the field stability. The new drift tubes have an optimized free-formed profile on the end plates in order to increase the shunt impedance. In special the assembly, positioning and alignment of the drift tubes can be tested and the frequency change can be investigated in this respect.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF079
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF080	Final Design of the FoS Alvarez-Cavity-Section for the Upgraded UNILAC	DTL, quadrupole, operation, simulation	920
	M. Heilmann, X. Du, L. Groening, M. Kaiser, S. Mickat, C. Mühle, A. Rubin, V. Srinivasan GSI, Darmstadt, Germany A. Seibel IAP, Frankfurt am Main, Germany
	The final design describes the First-of-Series (FoS) Alvarez-Cavity-section of the first tank being part of the new post-stripper DTL of the UNILAC. The FoS-cavity has an input energy of 1.358 MeV/u with 11 drift tubes (including quadrupole singlets) in a total length of 1.9 m and a diameter of 2 m with an operation frequency of 10⁸.4 MHz. The drift tubes will have a new shape profile at the end plates. The single layered quadruple singlets inside the drift tubes are pulsed with 10 Hz and will have a maximum field gradient of 51 T/m. The new drift tube design combines the new shape profile with the transverse and longitudinal installation space of the magnet. The FoS Alvarez-cavity will be part of the first section of the new Alvarez DTL. It shall be operated at nominal RF- and magnetic fields prior to procurement of the series.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF080
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF088	Final factory-side Measurements of the Next SC CH-Cavities for the HELIAC-Project	linac, resonance, heavy-ion, factory	943
	M. Basten, M. Busch, H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany K. Aulenbacher, W.A. Barth, V. Gettmann, T. Kürzeder, M. Miski-Oglu HIM, Mainz, Germany W.A. Barth, F.D. Dziuba, M. Heilmann, S. Yaramyshev GSI, Darmstadt, Germany
	Funding: Work supported by the EU Framework Programme H2020 662186 (MYRTE); Work supported by BMBF Contr. No. 05P15RFBA; The upcoming FAIR project (Facility for Antiproton and Ion Research) at GSI will use the existing UNILAC (UNIversal Linear Accelerator) as an injector to provide high intensity heavy ion beams at low repetition rates. As a consequence a new superconducting (sc) continous wave (cw) high intensity heavy ion Linac is required to provide ion beams above the coulomb barrier to keep the Super Heavy Element (SHE) physics program at GSI competitive on an international level. The fundamental Linac design comprises a high performance ion source, the High Charge State Injector (HLI) upgraded for cw-operation and a matching line (1.4 MeV/u) followed by a sc Drift Tube Linac (DTL). Four cryo modules each equipped with three Crossbar-H-mode (CH) structures provide for acceleration up to 7.3 MeV/u. The first section of this ambitious accelerator project has been successfully commissioned and tested with heavy ion beam from the HLI in 2017. It comprises two sc 9.3 T solenoids and a sc 217 MHz CH-cavity with 15 equidistant gaps as a demonstrator. The construction of the next two sc 217 MHz 8 gap CH-cavities is nearly finished and final factory-side measurements will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF088
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK002	Advanced Approach for Beam Matching along the Multi-Cavity SC CW Linac at GSI	linac, heavy-ion, emittance, proton	955
	S. Yaramyshev, W.A. Barth, M. Heilmann GSI, Darmstadt, Germany K. Aulenbacher IKP, Mainz, Germany K. Aulenbacher, W.A. Barth, V. Gettmann, T. Kürzeder, M. Miski-Oglu HIM, Mainz, Germany M. Basten, M. Busch, H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany
	A multi-stage program for the development of a heavy ion superconducting (sc) continuous wave (cw) linac is in progress at HIM (Mainz, Germany) and GSI (Darmstadt, Germany) under support of IAP (Frankfurt, Germany). In 2017 the first section of the CW-Linac has been successfully commissioned at GSI. Beam acceleration at the CW-Linac is foreseen to be performed by up to twelve multi-gap CH cavities. The linac should provide the beam for physics experiments, smoothly varying the output particle energy from 3.5 to 7.3 MeV/u, simultaneously keeping high beam quality. Due to a wide variation of the input- and output -beam energy for each cavity, a longitudinal beam matching to every cavity is of high importance. An advanced algorithm for an optimization of matched beam parameters under variable rf-voltage and rf-phase of each cavity has been developed. The description of the method and the obtained results are presented in the paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK002
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK003	Beam Dynamics Simulations for the New Superconducting CW Heavy Ion LINAC at GSI	linac, heavy-ion, cryomodule, solenoid	959
	M. Schwarz, M. Basten, M. Busch, H. Podlech IAP, Frankfurt am Main, Germany K. Aulenbacher IKP, Mainz, Germany K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu HIM, Mainz, Germany W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev GSI, Darmstadt, Germany
	Funding: Work supported by BMBF Contr. No. 05P15RFBA and EU Framework Programme H2020 662186 (MYRTE) For future experiments with heavy ions near the coulomb barrier within the super-heavy element (SHE) research project a multi-stage R&D program of GSI/HIM and IAP is currently in progress. It aims for developing a supercon-ducting (sc) continuous wave (CW) LINAC with multiple CH cavities as key components downstream the High Charge State Injector (HLI) at GSI. The LINAC design is challenging due to the requirement of intense beams in CW mode up to a mass-to-charge ratio of 6, while covering a broad output energy range from 3.5 to 7.3 MeV/u with unchanged minimum energy spread. Testing of the first CH-cavity in 2016 demonstrated a promising maximum accelerating gradient of E_a = 9.6 MV/m; the worldwide first beam test with this sc multi-gap CH-cavity in 2017 was a milestone in the R&D work of GSI/HIM and IAP. In the light of experience gained in this research so far, the beam dynamics layout for the entire LINAC has recently been updated and optimized.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK003
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK004	Superconducting CH-Cavity Heavy Ion Beam Testing at GSI	linac, heavy-ion, acceleration, emittance	962
	W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev GSI, Darmstadt, Germany K. Aulenbacher IKP, Mainz, Germany K. Aulenbacher, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu HIM, Mainz, Germany M. Basten, M. Busch, H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany
	Recently the first section of a standalone superconducting (sc) continuous wave (cw) heavy ion Linac as a demonstration of the capability of 217 MHz multi gap Crossbar H-mode structures (CH) has been commissioned and extensively tested with beam from the GSI- High Charge State Injector. The demonstrator set up reached acceleration of heavy ions up to the design beam energy and beyond. The required acceleration gain was achieved with heavy ion beams even above the design mass to charge ratio at high beam intensity and full beam transmission. This contribution presents systematic beam measurements with varying RF-amplitudes and phases of the CH-cavity, as well as versatile phase space measurements for heavy ion beams with different mass to charge ratio. The worldwide first and successful beam test with a superconducting multi gap CH-cavity is a milestone of the R&D work of Helmholtz Institute Mainz (HIM) and GSI in collaboration with Goethe University Frankfurt (GUF) in preparation of the sc cw heavy ion Linac project and other cw-ion beam applications.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK004
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK005	Upgrade Plan of J-PARC MR - Toward 1.3 MW Beam Power	operation, experiment, injection, proton	966
	T. Koseki KEK, Ibaraki, Japan
	The Main Ring Synchrotron (MR), a 30-GeV slow cycling proton synchrotron, delivers intense proton beam to a long-baseline neutrino oscillation experiment, T2K, by fast extraction and to an experimental facility, which is called hadron hall by slow extraction. The achieved beam intensities for routine operations are 470 kW ( 2.4 x 10¹⁴ ppp) for the fast extraction and 44 kW ( 5.1 x 10¹³ ppp) for the slow extraction. In order to increase the beam intensity, a plan to replace the magnet power supplies are now in progress for operation with a higher repetition rate. After the replacement, the cycle time will be shortened about a half and increase beam intensities two times larger for the fast extraction. In addition, a further upgrade plan for the fast extraction is mainly reinforcement of rf power supplies. The goal of the upgrade plan is reaching 1.3 MW beam power for the neutrino experiment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK005
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK011	Present Status and Future Upgrades of the J-PARC Ring RF Systems	proton, power-supply, operation, controls	984
	M. Yoshii, M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama KEK, Tokai, Ibaraki, Japan M. Nomura, T. Shimada, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan
	J-PARC is the multipurpose research institutes. 10 years have passed since the user operation started. We have been considering the upgrades for the future and the target beam powers for 3 GeV rapid cycling synchrotron (RCS) and 30GeV Main ring (MR) are 1.5MW and 1.3MW. To achieve a 1.5MW of RCS output beam power, increasing the number of Linac proton particles is necessary. For accelerating such higher beam current, the rf systems in the RCS need to upgrade an accelerating voltage and to take account of heavier beam loading. In case of the MR, increasing the number of proton is not appropriate from the viewpoint of space charge effects. We chose to shorten the MR cycle time. The required RF voltages become almost double. All nine systems have been replaced with the higher accelerating gradient RF systems using a newly developed magnetic alloy material. At present, the proton beam of 470kW is being delivered with a cycle time of 2.48s. Beam powers of MR will plan to aim first at 750KW after replacing the magnet power supplies. But, to realize a 1.3MW beam power, upgrading the RF power sources will be necessary. We present the ring RF system status and their upgrades for the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK011
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK012	Conceptual Design of a Single-Ended MA Cavity for J-PARC RCS Upgrade	acceleration, operation, vacuum, power-supply	987
	M. Yamamoto, M. Nomura, T. Shimada, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii KEK, Tokai, Ibaraki, Japan
	The J-PARC RCS employes Magnetic Alloy (MA) loaded cavities and rf power is fed by vacuum tubes in push-pull operation. The multi-harmonic rf driving and the multi-harmonic beam loading compensation are realized due to the broadband characteristics of the MA. However, the push-pull operation has disadvantages in the multi-harmonics. An unbalance of the anode voltage swing remarkably appears at very high intensity beam acceleration. In order to avoid the unbalance, a single-ended MA cavity is considered for the RCS beam power upgrade because no unbalance arises intrinsically. We will describe the conceptual design of the single-end MA cavity for the RCS upgrade.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK015	The SARAF-LINAC Project 2018 Status	linac, cryomodule, status, controls	994
	N. Pichoff, D. Chirpaz-Cerbat, R. Cubizolles, J. Dumas, R.D. Duperrier, G. Ferrand, B. Gastineau, P. Gastinel, F. Gougnaud, M. Jacquemet, C. Madec, Th. Plaisant, F. Senée, A. Sutra-Fourcade, D. Uriot IRFU, CEA, University Paris-Saclay, Gif-sur-Yvette, France D. Berkovits, J. Luner, A. Perry, E. Reinfeld, J. Rodnizki Soreq NRC, Yavne, Israel M. Di Giacomo GANIL, Caen, France
	SNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). CEA is in charge of the design, construction and commissioning of the MEBT line and the superconducting linac (SARAF-LINAC Project). The prototypes of the 176 MHz NC rebuncher, SC cavities, RF coupler and SC Solenoid-Package are under construction and their test stands construction or adaptation is in progress at Saclay. Meanwhile, the cryomodules and the global system just passed their Critical Design Reviews. This paper presents the status of the SARAF-LINAC Project at April 2018.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK015
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL009	Studying a Prototype of Dual-beam Drift Tube Linac	DTL, rfq, simulation, acceleration	1020
	T. He, L. Lu, W. Ma, L.P. Sun, C.C. Xing, X.B. Xu, L. Yang IMP/CAS, Lanzhou, People's Republic of China
	For generating high-intensity ion beams from linear ac-celerators, a multi-beam acceleration method which in-volves multiple accelerating beams to suppress the defo-cusing force from space charge effects, then integrating these beams by a beam funneling system, has been pro-posed. An Inter-digital H-mode (IH) two-beam type radio frequency quadrupole (RFQ) with accelerating 108mA (54mA/channel×2) carbon ion from 5 to 60 keV/ u and an IH four-beam RFQ with accelerating 160.8mA (40.2mA/channel×4) carbon ion from 3.6 to 41.6 keV/u had been successfully designed for low energy heavy ion acceleration [1]. In order to demonstrate that an IH dual-beam drift tube linac (DB-DTL) is suitable for high-intensity heavy ion beam acceleration in middle energy region, we has been developing a DB-DTL prototype by using three dimensional electromagnetic CST MicroWave Studio (MWS) and using particles tracking Pi Mode Linac Orbit Calculation (PiMLOC) [2-3]. According to the simulation results, the beam dynamics design and elec-tromagnetic design will be presented in this paper. * Shota. Iketa et al., Nucl. Instr. and Meth. in Phys. Res. B.239-243 (2017).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL009
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL011	Low Power Test and Tuning of the LEAF RFQ	rfq, quadrupole, dipole, operation	1028
	L. Lu, T. He, Y. He, W. Ma, L.B. Shi, L.P. Sun, C.C. Xing, X.B. Xu, L. Yang, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China
	A continuous wave (CW) four-vane radio frequency quadrupole (RFQ) accelerator is under construction for the Low Energy Accelerator Facility (LEAF) at Institute of Modern Physics (IMP). The 5.96 m RFQ will operate with the capability of accelerating all ion species from proton to uranium from 14 keV/u up to 500 keV/u. In this paper, the low power test and tuning results of the RFQ accelerator, including the test of the separate sections and the whole cavity, will be presented. After the final tuning, the relative error of the quadrupole field is within 2% and the admixture of the dipole modes are below 4% of the quadrupole mode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL011
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL012	Design and Fabrication of Hybrid RFQ Prototype	DTL, rfq, linac, site	1032
	P.Y. Yu, Y. He, C.X. Li, G.Z. Sun, F.F. Wang, Z.J. Wang, B. Zhang, T.M. Zhu IMP/CAS, Lanzhou, People's Republic of China
	Hybrid RFQ is proposed as a potential good choice at the low-energy range of linear accelerator. The complexi-ty of mechanical design and difficulty of fabrication are part of reasons impeding application of it and similar structures. In order to explore the practicable structure and research on RF parameters of this accelerating struc-ture, an aluminium prototype is developed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL022	Low-Reflection RF Window for ACS Cavity in J-PARC Linac	Windows, linac, proton, impedance	1051
	J. Tamura, Y. Kondo, T. Morishita JAEA/J-PARC, Tokai-mura, Japan H. Ao FRIB, East Lansing, USA F. Naito, M. Otani KEK, Tokai, Ibaraki, Japan Y. Nemoto Nippon Advanced Technology Co., Ltd., Tokai, Japan
	In the Japan Proton Accelerator Research Complex (J-PARC) linac, the Annular-ring Coupled Structure (ACS) cavities have been stably operating. To maintain this operation availability, we manufactured three backups of the pillbox-type RF windows for the ACS cavities in fiscal year 2015 and 2017. It is desirable to minimize the RF reflection of the RF window to prevent standing waves from exciting between the cavity and the RF window, and not to significantly change the optimized coupling factor between the cavity and the waveguide. To realize the minimization, the relative permittivities of the ceramic disks of the RF windows were evaluated by measuring the resonant frequencies of the pillbox cavity containing the ceramic disk. On the basis of the evaluated relative permittivities, the pillbox-part lengths of the RF windows were determined. The measured Voltage Standing Wave Ratios (VSWRs) of the manufactured RF windows are just about 1.08 and these are applicable for the practical use.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL022
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL029	Harmonictron	acceleration, proton, operation, synchrotron	1063
	Y. Mori Kyoto University, Research Reactor Institute, Osaka, Japan H. Arima, N. Ikeda, Y. Yonemura Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka, Japan Y. Waga Kyushu University, Hakozaki, Japan
	The possibility of high intensity hadron/lepton accelerator based on a vertical scaling FFAG with harmonic number jump acceleration, named "Harmonictron", has been proposed. The presentation gives a design example of the Harmonictron for accelerating protons from 50 MeV to 500 MeV for generation intense secondary particles such as muon, neutron etc.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL029
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL031	Errors Study of a Double-Pass Recirculating Superconducting Proton Linac	linac, proton, emittance, quadrupole	1069
	Y. Tao, K. Hwang, J. Qiang LBNL, Berkeley, California, USA
	The concept of recirculating superconducting proton linac was recently proposed. Beam dynamics simulations were carried out in a double-pass recirculating proton linac using a single bunch. Although all the beam line elements should be installed following the designed values, in reality, there exist machine imperfections that will cause beam off-centering and even particle losses. In this paper, we report on the study of the static and dynamic errors from RF cavities and magnetic focusing elements in the double-pass recirculating proton linac.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL031
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL032	A Variable Field Phase-Shifter for Recirculating Proton Linacs	linac, dipole, proton, superconducting-cavity	1072
	Y. Tao, J. Qiang LBNL, Berkeley, California, USA
	The recirculating superconducting proton linac that has a potential to substantially save accelerator cost was re-cently proposed. It consists of three sections to accelerate the continues-wave (CW) beam to multiple GeVs. In the first section, the beam passes the linac two times. In the second and third sections, the beam goes through the linac four and six times. A phase-shifter is needed to meet the synchronous acceleration condition for multi-pass accel-eration using the same RF cavity due to the phase slip-page of the proton beam. Here we present the design of a variable field rectangular bend phase-shifter in which the beam goes to a different path in each pass inside the mag-net to meet the synchronous condition.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL032
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL039	Commissioning of the FRIB RFQ	rfq, controls, MMI, dipole	1090
	H.T. Ren, J.F. Brandon, N.K. Bultman, M.G. Konrad, H. Maniar, D.G. Morris, P. Morrison, G. Pozdeyev, X. Rao, R. Walker, S. Zhao FRIB, East Lansing, USA
	Funding: This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 #wei@frib.msu.edu The radio-frequency quadrupole (RFQ) at the Facility for Rare Isotope Beams (FRIB) is a 4-vane type cavity designed to accelerate heavy ion beams with charge states Q/A between 1/7 and 1/3 from 12 keV/u to 0.5 MeV/u. The RFQ was assembled in the FRIB tunnel in November 2016. Bead-pull measurements and tuning were performed with low RF power. The RFQ has been conditioned to 59 kW in August 2017, which is sufficient to accelerate the Key Performance Parameter (KPP) beams, Argon and Krypton. The RFQ has been successful-ly commissioned with KPP beams in CW regime in Octo-ber 2017. 40Ar⁹⁺ and 86Kr¹⁷⁺ beams were accelerated by the FRIB RFQ in the CW regime to the designed energy of 0.5 MeV/u. With the multi-harmonic buncher operation-al, the FRIB RFQ commissioning has been completed with bunched beam in February 2018. The beam trans-mission efficiency through the RFQ was in good agree-ment with PARMTEQ simulation results. The detailed results from the FRIB RFQ tuning, high power condition-ing and beam commissioning will be presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL039
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL045	Towards Operational Scalability for H⁻ Laser Assisted Charge Exchange	laser, experiment, operation, radiation	1110
	S.M. Cousineau, A.V. Aleksandrov, T.V. Gorlov, Y. Liu, M.A. Plum, A. Rakhman, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA D.E. Johnson, S. Nagaitsev Fermilab, Batavia, Illinois, USA M.J. Kay UTK, Knoxville, Tennessee, USA
	The experimental development of H⁻ laser assisted charge exchange, a.k.a. laser stripping, has been ongoing at the SNS accelerator since 2006 in a three-phase approach. The first two phases associated with proof-of-principle and proof-of-practicality experiments have been successfully completed and demonstrated >95% H⁻ stripping efficiency for up to 10 us. The final phase is a proof-of-scalability stage to demonstrate that the method can be deployed for realistic beam duty factors. The experimental component of this effort is centered on achieving high efficiency stripping through the use of a laser power amplification scheme to recycle the macropulse laser light at the interaction point of the H⁻ stripping. Such a recycling cavity will be necessary for any future operational laser stripping system with at least millisecond duration H⁻ pulses. A second component of the proof-of-scalability phase is to develop a conceptual design for a realistic laser stripping scheme. The status of these efforts and challenges associated with deploying the recycling cavity into the laser stripping experiment will be described in this talk.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL045
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL049	SNS Proton Power Upgrade Status	linac, scattering, proton, injection	1120
	M.A. Plum, G. A. Bloom, M.S. Champion, J. Galambos, M.P. Howell, S.-H. Kim, J. Moss, B.W. Riemer, K.S. White ORNL, Oak Ridge, Tennessee, USA R.B. Saethre, R. W. Steffey ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. This research was supported by the DOE Office of Science, Basic Energy Science, Scientific User Facilities. The Spallation Neutron Source (SNS) Proton Power Upgrade (PPU) project aims to double the proton accelerator beam power from 1.4 to 2.8 MW. Over the past year PPU has completed the reviews necessary for Critical Decision-1 approval. The baseline design choices are being refined, and a cost-effective approach has been identified. The beam energy will be increased by 30% and the beam current capability improved by ~50%. The sub-system improvements and anticipated schedule will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL049
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL050	Progress Work on a CW Deuteron RFQ with Magnetic Coupling Windows	rfq, experiment, coupling, Windows	1123
	Q. Fu, M.J. Easton, P.P. Gan, S.L. Gao, H.P. Li, Y.R. Lu, Q.Y. Tan, Z. Wang, K. Zhu PKU, Beijing, People's Republic of China W.P. Dou, Y. He IMP/CAS, Lanzhou, People's Republic of China
	Funding: This work was supported by the National Basic Research Program of China (Grant No. 2014CB845503). A new 162.5 MHz RFQ has been built for a joint 973 project between Peking University (PKU) and Institute of Modern Physics (IMP). It is designed to deliver 50-mA deuteron beams to 1 MeV in CW mode, with an inter-voltage of 60 kV and a length of 1.809 m. Due to its window-type structure, the RFQ has compact cross-section, sufficient mode separation and high specific shunt impedance. It consists of two segments fabricated and installed at IMP. The assembling error of the cavity is less than 0.05 mm. The RF measurements show good electrical properties of the resonant cavity with a measured unloaded quality factor equal to 96.4% of the simulated value. After tuning, we obtained the nominal frequency and field unbalance within 1.0%. Preparation of high-power test of this RFQ is underway. This paper will cover the fabrication details and RF measurements, as well as the progress of high-power test.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL050
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL052	Multi-Physics Analysis of a CW IH-DTL for CIFNEF	DTL, neutron, linac, operation	1129
	Q.Y. Tan, M.J. Easton, Q. Fu, P.P. Gan, H.P. Li, Y.R. Lu, Z. Wang PKU, Beijing, People's Republic of China
	The Compact Intense Fast NEutron Facility (CIFNEF) project aims to produce high intense neutrons via the 7Li (d, n) 8Be reaction using a 5 MeV, 10 mA deuteron linac. The main components of the linac are an ion source, a short radio frequency quadrupole (RFQ) and an interdigi-tal H-mode drift tube linac (IH-DTL). The IH-DTL will accelerate the continuous wave (CW) deuteron beam from 1 MeV to 5 MeV with a total cavity length of 1.25 m using Kombinierte Null Grad Struktur (KONUS) design, achieving an accelerating gradient of 3.2 MV/m. The RF power loss for the whole cavity is estimated to be 85 kW. This high power loss is a significant challenge to the cooling design, as it could cause large rises in tempera-ture, thermal deformation and frequency drift. A detailed multi-physics analysis of the CW IH-DTL is presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL052
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL068	The Development of a Nw Fast Harmonic Kicker for the JLEIC Circulator Cooling Ring	kicker, emittance, simulation, electron	1171
	G.-T. Park, F. Fors, J. Guo, R.A. Rimmer, H. Wang, S. Wang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. After the first half-scale, 5 harmonic kicker cavity prototyping * for the JLEIC's CCR/ERL electron cooler and the beam dynamic simulation study of the 10-turn CCR *. The optimized circulation cooling turns has been changed to 11 and only 5 odd-harmonic modes from 86.6 MHz to 779.4 MHz plus a DC bias are needed for the harmonic RF kicker system. The new cavity design including the electromagnetic and thermal cooling optimization and its 11 turns beam bunch tracking simulation with the new numerology of RF deflecting voltages will be presented. Further design specifications for its RF harmonic drive and the broadband RF window, coupler and circulator component will be given for handling 5 kW of total RF power. Y, Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 122001 (2016). ** Y. Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 084201 (2016).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL068
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL075	Mechanical Design and Error Analysis of a 325 MHz IH-DTL Test Cavity	DTL, alignment, simulation, linac	1186
	R. Tang, C.T. Du, X. Guan, K.D. Man, C.-X. Tang, X.W. Wang, Q.Z. Xing, S.X. Zheng TUB, Beijing, People's Republic of China J. Li NUCTECH, Beijing, People's Republic of China
	A 325 MHz interdigital H-mode drift tube linac (IH-DTL) test cavity with a modified KONUS beam dynamics is under fabrication at Tsinghua University. The inner diameter of the tank increases from 196.8 to 232.6 mm. The mechanical design is considered carefully because of its small geometry. A three-piece design has been adopted in the mechanical design. The error analysis is carried out to determine the error requirement of machining and alignment. The details of mechanical design and error analysis is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL075
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBD5	Performance of Nanometre-Level Resolution Cavity Beam Position Monitors at ATF2	feedback, dipole, electron, kicker	1212
	T. Bromwich, D.R. Bett, N. Blaskovic Kraljevic, R.M. Bodenstein, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan JAI, Oxford, United Kingdom S. Araki, A. Aryshev, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan P. Bambade, S. Wallon LAL, Orsay, France S.W. Jang Korea University Sejong Campus, Sejong, Republic of Korea
	A system of three low-Q cavity beam position monitors (BPMs), installed in the interaction point (IP) region of the Accelerator Test Facility (ATF2) at KEK, has been designed and optimised for nanometre-level beam position resolution. The BPMs are used to provide an input to a low-latency, intra-train beam position feedback system deployed in single-pass, multi-bunch mode with the aim of demonstrating intra-train beam stabilisation on electron bunches of charge ~1 nC separated in time by 280 ns. In 2016 the BPM resolution was demonstrated to be below 50 nm using the raw measured vertical positions at the three BPMs. New results will be presented utilising integrated sampling of the raw waveforms, improved BPM alignment and modified cavities to demonstrate a vertical position resolution on the order of 20 nm.
	Slides TUZGBD5 [8.557 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBD5
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBE4	Toward High-Power High-Gradient Testing of mm-Wave Standing-Wave Accelerating Structures	experiment, coupling, accelerating-gradient, diagnostics	1224
	E.A. Nanni, V.A. Dolgashev, A.A. Haase, J. Neilson, S.G. Tantawi SLAC, Menlo Park, California, USA S. Jawla, R.J. Temkin MIT/PSFC, Cambridge, Massachusetts, USA S. C. Schaub MIT, Cambridge, Massachusetts, USA B. Spataro INFN/LNF, Frascati (Roma), Italy
	Funding: This work is supported in part by Department of Energy contract DE-AC02-76SF00515 (SLAC) and DE-SC0015566 (MIT). We will preliminary testing results for single-cell accelerating structures intended for high-gradient testing at 110 GHz. The purpose of this work is to study the basic physics of ultrahigh vacuum RF breakdown in high-gradient RF accelerators. The accelerating structures consist of pi-mode standing-wave cavities fed with TM01 circular waveguide mode. We fabricated of two structures one in copper and the other in CuAg alloy. Cold RF tests confirm the design RF performance of the structures. The geometry and field shape of these accelerating structures is as close as practical to single-cell standing-wave X-band accelerating structures more than 40 of which were tested at SLAC. This wealth of X-band data will serve as a baseline for these 110 GHz tests. The structures will be powered with a MW gyrotron oscillator that produces microsecond pulses. One megawatt of RF power from the gyrotron may allow us to reach a peak accelerating gradient of 400 MeV/m.
	Slides TUZGBE4 [4.644 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE4
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBE5	A Combined Temperature and Magnetic Field Mapping System for SRF Cavities	operation, SRF, niobium, experiment	1228
	J.M. Köszegi, K. Alomari, J. Knobloch, O. Kugeler, B. Schmitz HZB, Berlin, Germany
	In the past decade, a significant improvement of SRF cavity performance has been achieved, yet a number of performance limiting mechanisms, such as magnetic flux trapping, still exist. We present a diagnostics tool which combines flux expulsion measurement during the superconducting phase transition with temperature mapping during operation. This system has a time resolution for both temperature and magnetic field mapping of 2 ms for full cavity coverage, so that short-lived events, including cavity quenches, can easily be resolved.
	Slides TUZGBE5 [1.358 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE5
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBF3	Betatron Core Slow Extraction at CNAO	betatron, extraction, synchrotron, acceleration	1237
	L. Falbo, E. Bressi, S. Foglio, C. Priano CNAO Foundation, Milan, Italy
	CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. Beam is extracted with a momentum selection scheme in which beam enters the third order resonance driven by a betatron core. When irradiating a tumor, it is thought as divided in the longitudinal plane in several slices while each slice is divided in the transverse plane in several spots called voxels. Considering the dose uniformity that can be obtained during extraction, the machine must extract an average intensity related to the voxel that requires less dose. Therefore during a treatment, for some slices, a technique is needed to lower the extracted beam intensity with respect to the nominal one. A way to guarantee the correct average intensity according to the treatment planning requirements, is to introduce a mechanical filter (a degrader) that reduces the intensity of the accelerated particles. However this method used in the first treatments at CNAO showed some disadvantages and it has been replaced by what has been called the "dynamic betatron" method. The paper shows the implementations and the advantages of this method in the CNAO treatments.
	Slides TUZGBF3 [2.146 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBF3
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBF5	KlyLac Prototyping for Borehole Logging	klystron, linac, feedback, simulation	1244
	A.V. Smirnov, R.B. Agustsson, M.A. Harrison, A.Y. Murokh, A.Yu. Smirnov RadiaBeam Systems, Santa Monica, California, USA S. Boucher, T.J. Campese, K.J. Hoyt RadiaBeam, Los Angeles, California, USA E.A. Savin MEPhI, Moscow, Russia A.A. Zavadtsev Nano, Moscow, Russia
	Funding: Work supported by the U.S. Department of Energy (award No. DE-SC0015721) Linac-based system for borehole logging exploits KlyLac approach combing klystron and linac sharing the same electron beam, vacuum volume, and RF network enabling self-oscillation due to a positive feedback. The KlyLac prototype design tailors delivering ~1 MeV electrons in a linac section using part of the beam injected from a sheet beam klystron (SBK). The linac part is based on a very robust, high group velocity, cm-wave, and a standing wave accelerating structure of a 'cross-pin' type supplied by a sampler. The SBK part features a permanent magnet solenoid focusing, relatively low voltage, and high aspect ratio beam. The main SBK characteristics (perveance, power, and efficiency) are expected to be similar to that for a magnetron.
	Slides TUZGBF5 [3.280 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBF5
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF002	A Cu Photocathode for the Superconducting RF Photoinjector of BERLinPro	cathode, gun, SRF, laser	1247
	J. Kühn, M. Bürger, A. Frahm, A. Jankowiak, T. Kamps, G. Klemz, G. Kourkafas, A. Neumann, N. Ohm, M. Schmeißer, M. Schuster, J. Völker HZB, Berlin, Germany P. Murcek, J. Teichert HZDR, Dresden, Germany
	The initial commissioning of the Superconducting RF (SRF) photoinjector is done with a Cu photocathode due to its robustness with regard to interactions with the SRF cavity of the injector. Here we present the preparation and characterization of a Cu photocathode plug and the diagnostics to insert the photocathode in the back wall of the SRF cavity. A polycrystalline bulk Cu plug was polished, particle free cleaned and characterized by x-ray photoelectron spectroscopy. During the transfer of the photocathode insert into the gun module the whole process was controlled by several diagnostic tools monitoring the insert position as well as RF, vacuum and cryogenic signals. We discuss the challenges of the photocathode transfer into an SRF cavity and how they can be tackled.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF002
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF003	Dynamic Tuning of the APS-U Booster 5-cell Cavities	booster, resonance, extraction, coupling	1251
	G.J. Waldschmidt, M. Abliz, T.G. Berenc, D. Horan, U. Wienands ANL, Argonne, Illinois, USA
	The booster synchrotron for the APS-U is being upgraded to accommodate high-charge bunches, up to 20 nC, for extraction into the MBA lattice. The booster is required to operate at 85% efficiency in order to achieve bunch swap-out into the storage ring. In order to compensate for significant beam-loading effects as well as support a frequency ramp to achieve higher efficiency, a ferrite tuner is being considered to dynamically adjust the cavity frequency. A tuner design will be presented that spans 60 kHz and utilizes a low-loss YIG garnet similar to that used in the Recycler Ring at Fermilab.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF003
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF016	Application of SVD Analysis to Deflecting Cavitiy Space Harmonics	simulation, timing, data-analysis, experiment	1283
	C. Yao, L. Emery, D. Hui, H. Shang, Y.P. Sun ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Singular value decomposition (SVD) analysis is a powerful tool for identifying different spatial and timing variation patterns in many fields of researches. Recently we applied complex SVD method to space harmonic analysis of a 13-cell defecting cavity that is built and installed in the APS linac injector for beam phase space characterization and emittance exchange experiments. Real and imaginary space harmonics components are extracted from CST simulated data. Fields inside the iris were expressed in analytic forms and produced good agreement. Work is underway to implement the results into elegant simulation model.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF016
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF032	RF Conceptual Design of Normal Conducting Cavity for an eRHIC Rapid Cycling Synchrotron	electron, GUI, coupling, vacuum	1316
	B. P. Xiao, M. Blaskiewicz, J.M. Brennan, D. Holmes, K.S. Smith, T. Xin, A. Zaltsman BNL, Upton, Long Island, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The Rapid Cycling Synchrotron (RCS) for the eRHIC Ring-Ring design will provide on energy injection (up to 18 GeV) of high charge, polarized electron bunches to the eRHIC electron storage ring. The RF system comprises a large number of 563MHz fundamental cavities, providing up to 45MV per turn. The cavities will operate in pulsed mode with <20% duty factor, at a repetition rate of 1 Hz. In this paper we report the conceptual RF design of the cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF032
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF034	Measuring the Electrical Center and Field Flatness of 704 MHz Deflecting Cavity for LEReC with Wire Stretching System	simulation, diagnostics, pick-up, experiment	1320
	T. Xin, J.M. Brennan, J.C.B. Brutus, K. Mernick, K.S. Smith, B. P. Xiao, A. Zaltsman BNL, Upton, Long Island, New York, USA W. Johnson SBU, Stony Brook, New York, USA H. Wang JLab, Newport News, Virginia, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. 704 MHz deflecting cavity was designed for the Low Energy RHIC electron Cooling (LEReC) project. The cavity will serve as a major component in diagnostic line. In LEReC project the requirement on the energy spread of the electron beam is extremely high (better than 10^-4) and the diagnostic system has to to be designed accordingly. The 704 MHz transverse deflecting cavity provides the vertical kick to the beam after it passes through the dispersion dipole so that we can measure the energy spread of the core of the bunch. Traditional way of determining the electrical center of the cavity involves the needle pulling and integration of the signal which is prone to the cumulative error. We present the measurement result from a wire stretching system that is much more efficient and accurate compared to the bead/needle pulling method. Both simulation and experimental results are shown in this paper and the potential in further application is discussed at the end.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF034
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF042	Design of a High Dose Rate Micro-Focused X-Ray Source	electron, target, emittance, dipole	1346
	X. He, S.Q. Liao, J. Long, J. Shi, W. Wang, L. Yang CAEP/IFP, Mainyang, Sichuan, People's Republic of China
	High energy X-ray computer tomography has wide application in industry, especially in quality control of complicated high-tech equipment. In many applications, higher spatial resolution is needed to discover smaller defects. Decreasing the spot size of the X-Ray source is a promising way to get higher spatial resolution. Rhodotron have been used to produce high power CW electron beam in hundreds of kilowatts level. In this paper, we propose to use an improved Rhodotron to generate high brightness electron beam with high average power. Beam dynamics study shows that when producing tens of kilowatts electron beam, the normalized RMS emittance can be lower than 10 μm, and the relative RMS energy spread can be lower than 0.2%. The beam can be focused to a spot size of about 100μm by using a series of quadruple, and converted to X-Ray by using a rotating target within several kilowatts beam power. Improved Rhodotron proposed in this paper is a good candidate of X-ray source for high resolution high energy industrial CT systems.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF042
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF048	On-Axis Beam Accumulation Based on a Triple-Frequency RF System for Diffraction-Limited Storage Rings	injection, simulation, accumulation, photon	1359
	S.C. Jiang, Z. Duan, G. Xu IHEP, Beijing, People's Republic of China
	Since the multi-bend achromats have been applied to lattice design in the future light source to achieve ultralow emittance, strong sextupoles and concomitant nonlinearities restrict its performance to a certain extent. The empirical understanding is the exclusion of conventional off-axis injection scheme on these light sources. In this paper, we will present a new on-axis beam accumulation scheme, which is based on the triple-frequency RF system. By means of delicate superposition of RF voltage with fundamental and two other harmonic frequencies, a commodious and steady main bucket is able to be formed. The electron bunch from the injector will be kicked into the main bucket on-axis with a reasonable time offset to the circular bunch, and this process may make the minimal disturbance to the experiment users while operating on the top-up mode. The application of this scheme to the High Energy Photon Source (HEPS) will be discussed in the paper, corresponding simulation results are also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF048
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF074	Control of Collective Effects by Active Harmonic Cavity in an MBA-based Light Source with Application to the PETRA Upgrade	impedance, emittance, lattice, synchrotron	1433
	Y.-C. Chae, J. Keil DESY, Hamburg, Germany
	Based on the reference lattice for PETRA IV* we investigated collective effects with non-zero current. Out of many possibilities we firstly computed the intrabeam-scattering (IBS) effects on the emittance as well as lifetime as a function of current. The result indicated that PETRA IV would benefit from the reduced peak current when the harmonic cavity lengthens the bunch. The operating point of harmonic cavity was explored by tracking simulations as well as analytic formula. In order to compute the energy spread and bunch length we had used the known impedance function of the APS*. In this way more realistic estimation of IBS effects was expected. However, because of the complex nature of PETRA IV lattice, which includes achromatic cells for undulators, arc cells of octants and straight sectors for damping wigglers, we simplify the longitudinal dynamics by assuming the ring made of 92 multi-bend-achromat (MBA) cells. The optics is approximated as a linear-chromatic transfer map enabling fast tracking and the ring impedance is concatenated into the one location. The detailed collective effects with and without harmonic cavities are presented in the paper. J. Keil, "A PETRA IV Lattice Based on Hybrid Seven Bend Achromats", these proceedings. ** Y.-C. Chae and Y. Wang, "Impedance Database II for the Advanced Photon Source Storage Ring", Proc. PAC2007.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF074
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF080	Progress on Multibunch FEL Performance at FLASH	operation, FEL, controls, accelerating-gradient	1452
	T. Hellert, Ch. Schmidt DESY, Hamburg, Germany
	At the SASE-FEL user facility FLASH, superconducting TESLA-type cavities are used for acceleration. The high achievable duty cycle allows for operating with long bunch-trains, hence considerably increasing the efficiency of the machine. However, RF induced intra-bunch-train trajectory variations were found to be responsible for significant variations of the SASE intensity within one bunch train. This work presents the latest achievements in improving the multi-bunch FEL performance by reducing the intra-bunch-train variation of RF parameters. Particular attention is given to the static and dynamic detuning of the cavities. It will be shown that the current level of LLRF control is suitable to limit the variation of RF parameters considerably.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF080
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF081	Microphonic Detuning Induced Coupler Kick Variation at LCLS-II	linac, laser, free-electron-laser, beam-loading	1456
	T. Hellert DESY, Hamburg, Germany W. Ackermann, H. De Gersem TEMF, TU Darmstadt, Darmstadt, Germany C. Adolphsen, Z. Li, C.E. Mayes SLAC, Menlo Park, California, USA
	The LCLS-II free-electron laser will be an upgrade of the existing Linac Coherent Light Source (LCLS), including a 4 GeV CW superconducting linac based on the TESLA technology. The high quality factor of the cavity makes it very sensitive to vibrations. The shift of its eigenfrequency (i.e., detuning) will be compensated by the power source in order to assure a constant accelerating voltage. Significant variations of the forward power are expected which result in coupler kick variations induced by the fundamental power coupler. In this work we estimate the magnitude of trajectory jitter caused by these variations. High precision 3D field maps including standing and traveling-wave components for a cavity with the LCLS-II coupler design are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF081
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF086	Status of the ARES RF Gun at SINBAD: From its Characterization and Installation towards Commissioning	gun, linac, status, electron	1474
	B. Marchetti, R.W. Aßmann, S. Baark, F. Burkart, U. Dorda, K. Flöttmann, I. Hartl, J. Hauser, J. Herrmann, M. Hüning, K. Knebel, O. Krebs, G. Kube, W. Kuropka, S. Lederer, F. Lemery, F. Ludwig, D. Marx, F. Mayet, M. Pelzer, I. Peperkorn, F. Poblotzki, S. Pumpe, J. Rothenburg, H. Schlarb, M. Titberidze, G. Vashchenko, T. Vinatier, P.A. Walker, L. Winkelmann, K. Wittenburg, S. Yamin, J. Zhu DESY, Hamburg, Germany
	The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) is foreseen to host multiple experiments relating to the production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD-ARES linac will be a conventional S-band linear RF accelerator allowing the production of low charge (0.5 pC - tens pC) ultra-short electron bunches (FWHM length =< 1 fs - few fs) with 100 MeV energy. The installation of the linac will proceed in stages. In this paper we report on the status of the characterization of the ARES RF gun and the installations of the related infrastructure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF086
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMK006	Sub-fs Electron Bunch Generation Using Emittance Exchange Compressor	emittance, simulation, sextupole, electron	1501
	J.M. Seok, M. Chung UNIST, Ulsan, Republic of Korea M.E. Conde, J.G. Power ANL, Argonne, Illinois, USA G. Ha PAL, Pohang, Republic of Korea
	Sub-fs electron bunch has been pursued in the last decade using several different methods. These methods rely on one of the velocity difference or path length difference to compress a long bunch to sub-fs bunch. Here, we introduce a new method to generate the compression. Emittance Exchange (EEX) beamline makes transverse-to-longitudinal exchange of phase space. In this beamline, a transverse focusing at the upstream introduces a longitudinal compression at the downstream due to the exchange. Since this exchange scheme does not rely on the velocity or the path length differences, it does not require any longitudinal manipulation (e.g. chirp), and it could generate a short bunch with well-controlled nonlinear effects using nonlinear magnets. We present preliminary simulation results of EEX based bunch compression and sub-fs bunch generation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK006
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPML053	The BERLinPro SRF Photoinjector System - From First RF Commissioning to First Beam	cathode, SRF, operation, solenoid	1660
	A. Neumann, D. Böhlick, M. Bürger, P. Echevarria, A. Frahm, H.-W. Glock, F. Göbel, S. Heling, K. Janke, A. Jankowiak, T. Kamps, S. Klauke, G. Klemz, J. Knobloch, G. Kourkafas, J. Kühn, O. Kugeler, N. Leuschner, N. Ohm, E. Panofski, H. Plötz, S. Rotterdam, M.A.H. Schmeißer, M. Schuster, H. Stein, Y. Tamashevich, J. Ullrich, A. Ushakov, J. Völker HZB, Berlin, Germany
	Funding: The work is funded by the Helmholtz-Association, BMBF, the state of Berlin and HZB. Helmholtz-Zentrum Berlin (HZB) is currently constructing a high average current superconducting (SC) ERL as a prototype to demonstrate low normalized beam emittance of 1 mm-mrad at 100 mA and short pulses of about 2 ps. To attain the required beam properties, an SRF based photo-injector system was developed and during the past year underwent RF commissioning and was setup within a dedicated diagnostics beamline called Gunlab to analyze beam dynamics of both, a copper cathode and a Cs2KSb cathode as well as their quantum efficiency at UV and green light respectively. The medium power prototype - a first stage towards the final high power 100 mA design - presented here features a 1.4 x λ/2 cell SRF cavity with a normal-conducting, high quantum efficiency CsK2Sb cathode, implementing a modified HZDR-style cathode insert. This injector potentially allows for 6 mA beam current and up to 3.5 MeV kinetic energy, limited by the modified twin TTF-III fundamental power couplers. In this contribution, the first RF commissioning results of the photo-injector module will be presented including dark current analysis as well as measured beam properties with an initially installed Copper cathode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML053
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPML054	Microbeam Irradiation System with a Dielectric Laser Accelerator for Radiobiology Research	laser, electron, accelerating-gradient, radiation	1664
	K. Koyama KEK, Ibaraki, Japan Z. Chen The University of Tokyo, Tokyo, Japan T. Takahashi The University of Tokyo, The School of Engineering, Tokyo, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
	Funding: This work was supported by KAKENHI (Grant-in-Aid for Scientific Research)15H03595 and partly supported by NIMS Nanofabrication Platform in Nanotechnology Platform Project sponsored by the MEXT, Japan. A laser micro-irradiation (LMI) system is widely used in the field of radiobiology because of its acceptably small size. However, damage in a cell nucleus caused by the LMI system does not necessarily simulate a radiation effect. If the laser of the LMI system is replaced with a small-scale 1MeV-class accelerator such as a dielectric laser accelerator (DLA), experiments might be performed under conditions that are more realistic. The desirable configuration of the DLA for a compact micro-beam irradiation system is that laser pulses are transported to a dielectric structure by single-mode optical fibers and the laser energy is accumulated in an accelerator channel. The long and low-intensity laser pulse of 100 MW/cm², 10ps and a resonator with Q=10⁴ are capable of producing the light intensity of 1 TW/cm². The long laser pulse, i.e., low laser induced damage threshold intensity, decreases the acceleration gradient to about 1/3 of the ultra-short pulse irradiation of 100 fs. The length of the accelerator at long-laser pulse might be within the allowable range of several cm. The resonator scheme is useful only for the sub-relativistic regime because of the acceleration gradient.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML054
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPML066	Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices	plasma, simulation, emittance, scattering	1696
	P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA J.S. Ellison IIT, Chicago, Illinois, USA

Paper

Title

Other Keywords

Page

MOYGB1

Status and Future Strategy for Advanced High Power Microwave Sources for Accelerators

klystron, electron, operation, linac

12

F. Gerigk
CERN, Geneva, Switzerland

The need for more energy efficient high power microwave devices for accelerator applications continues to increase. This is important for development of cost effective accelerator designs that are coming up in the near future. Efforts are already in place to design new devices that could stretch the limits of RF power conversion to the highest levels possible. Devices including new technologies and design innovations like multi beam, increased number of cavities designs are being considered. Advances in the application of solid state amplifiers to accelerators are also being realized. This invited talk will cover the recent advances and status of such efforts. It will discuss future needs and a strategy for pursuing these efforts on a faster time scale for the benefit of the accelerator community.

Slides MOYGB1 [11.575 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOYGB1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOYGB2

The LCLS-II: A High Power Upgrade to the LCLS

linac, undulator, cryomodule, electron

18

J.N. Galayda
SLAC, Menlo Park, California, USA

Funding: The work is supported by DOE under grant No. DE-AC02-76SF00515
The LCLS-II is an upgrade of the LCLS X-ray FEL based on a 4 GeV superconducting RF linac. The LCLS-II is designed to produce 100's of Watts of X-rays from 200 eV up to 5 keV. The linac uses 1.3 GHz 9-cell cavities processed using the N2-doping technique and will be the first large scale CW SCRF linac with a Q of roughly 3x10¹⁰ at a gradient of 16 MV/m. The injector which will be commissioned in spring 2018, is based on the normal conducting CW RF APEX gun developed at LBNL. The LCLS-II will have two undulators: the soft X-ray undulator is a 39 mm period hybrid PM with an adjustable vertical gap to cover the range from 200 eV to 1.5 keV and hard X-ray undulator is a novel adjustable horizontal gap hybrid PM undulator with 26 mm period to generate vertically polarized X-rays from 1 to 5 keV. The talk will review the performance goals as well as the hardware fabrication.

Slides MOYGB2 [11.367 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOYGB2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOZGBD3

Performance of the First LCLS-II Cryomodules: Issues and Solutions

cryomodule, HOM, radiation, operation

34

N. Solyak, E. Cullerton, J. Einstein-Curtis, E.R. Harms, B.D. Hartsell, J.P. Holzbauer, T.N. Khabiboulline, A. Lunin, Y.M. Pischalnikov, R.P. Stanek, G. Wu
Fermilab, Batavia, Illinois, USA
O. Napoly
CEA/DSM/IRFU, France

LCLS-II 4 GeV linac is on the middle production stage. Linac contains 40 cryomodules of 1.3 GHz and 3 cryomodules of 3.9 GHz, including spares. Fermilab and JLAB share responsibility for cryomodule design, assembly and test. Paper will overview the performance of the cryomodules it the tests, lessons learned and modifications in design to improve performance.

Slides MOZGBD3 [8.630 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBD3

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOZGBF2

Status of the FAIR Project

proton, antiproton, target, dipole

63

P.J. Spiller, M. Bai, O. Boine-Frankenheim, A. Dolinskyy, F. Hagenbuck, C.M. Kleffner, K. Knie, S. Menke, C. Omet, A. Schuhmann, H. Simon, M. Winkler
GSI, Darmstadt, Germany
J. Blaurock, M. Ossendorf
FAIR, Darmstadt, Germany
I. Koop
BINP SB RAS, Novosibirsk, Russia
D. Prasuhn, R. Tölle
FZJ, Jülich, Germany

The realization of the new Facility for Antiproton and Ion Research, FAIR at GSI, Germany, has advanced significantly. The civil construction process of the Northern part of the building complex, including the excavation of the SIS100 synchrotron tunnel has been launched end of 2017. On site of the GSI campus, major preparations and upgrade measures for the injector operation of the existing accelerator facilities are ongoing and will be completed mid of 2018. The shielding of the SIS18 accelerator tunnel has been enhanced for the booster operation at high repetition rates and high intensity Proton beams. Two new transformer stations were set-up and commissioned which will provide the required pulse and common power for FAIR. All major contracts for series production of SIS100 components have been signed and a large number of the superconducting SIS100 magnets has been produced and accepted. Major testing infrastructures for superconducting magnets of SIS100 and Super-FRS have been set-up at JINR, CERN and GSI. Also for all other FAIR accelerator systems, the procurement of the components is progressing well

Slides MOZGBF2 [4.266 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOZGBF4

Evolution of the Superconducting Linac Output Energy at the Spallation Neutron Source

cryomodule, operation, linac, SRF

73

S.-H. Kim, D.E. Anderson, M.T. Crofford, M. Doleans, J. Galambos, S.W. Gold, M.P. Howell, M.A. Plum, D.J. Vandygriff
ORNL, Oak Ridge, Tennessee, USA
R. Afanador, D.L. Barnhart, B. DeGraff, J.D. Mammosser, C.J. McMahan, T.S. Neustadt, C.C. Peters, J. Saunders, D.M. Vandygriff
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
The SNS linac output energy has increased since the start of neutron production in FY2007. The various improvements that contributed to the increase of the linac output energy are LLRF/control system improvement, high voltage converter modulator system improvement, high-power RF system improvement, cryomodule repairs, spare cryomodule development and accelerating gradient improvement through in-situ plasma processing. In this paper, the history of the SNS SCL output energy is reported, and plans for the near-term future and for the Proton Power Upgrade (PPU) project are also presented.

Slides MOZGBF4 [34.185 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF4

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF012

Study of Crabbed Collision in eRHIC With a Combination of Strong-Strong and Weak-Strong Simulations

simulation, electron, proton, luminosity

105

Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, Y. Hao, C. Montag, V. Ptitsyn, V.V. Smaluk, F.J. Willeke
BNL, Upton, Long Island, New York, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the present design of the future electron-ion collider eRHIC at the Brookhaven National Laboratory, a crossing angle of 22~mrad between the electron and proton orbits at the interaction region is adopted. To compensate the geometric luminosity loss, a local compensation scheme with two sets of crab cavities for each beam is considered. In this article, we first carry out strong-strong beam-beam simulation to study possible coherent beam-beam instability. Under the assumption of no coherent beam-beam motion, we then carry out a weak-strong beam-beam simulation to determine the long-term stability of the proton beam with the equilibrium electron beam sizes extracted from the strong-strong beam-beam simulation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF020

Higher Order Mode Coupling Options for the eRHIC Crab Cavity

HOM, damping, coupling, impedance

121

Q. Wu, I. Ben-Zvi, S. Verdú-Andrés, B. P. Xiao
BNL, Upton, Long Island, New York, USA
I. Ben-Zvi
Stony Brook University, Stony Brook, USA

Funding: This work was supported by the US Department of Energy via Brookhaven Science Associates LLC under contract no. DE-SC0012704.
The eRHIC crab cavity adopts the double quarter wave structure developed at Brookhaven National Lab for the LHC Hi-Lumi upgrade crab cavities. The cavity's fundamental mode is at 338 MHz with the first higher order mode more than 180 MHz above that. We looked into the higher order mode distribution up to 2 GHz, and considered various locations and geometries of the coupling scheme. The cylindrical outer shell of the cavity allowed various possibilities for coupler port openings on all the walls, which were difficult for the narrow waist of the LHC double quarter wave crab cavities. Beam pipe absorbers are also options for simpler high frequency modes damping. Some preliminary high pass filter design will also be discussed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF020

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF022

Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities

luminosity, simulation, proton, LLRF

129

E. Yamakawa, R. Apsimon, A.C. Dexter
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Baudrenghien, R. Calaga, F.J. Galindo Guarch
CERN, Geneva, Switzerland

The High-Luminosity LHC (HL-LHC) crab cavities (CCs) will be installed on both sides of IP1 (ATLAS) and IP5 (CMS) to compensate for the geometric luminosity reduction due to the crossing angle. To cope with the increased beam current (0.55 A DC for LHC, 1.1 A for HL-LHC), the operation of the LLRF system has been changed: rather than fully compensating the transient beam loading, we allow the phase to vary along the turn (100 ps peak-peak with 1.1 A DC). This has been implemented at LHC since July 2017. The CCs have high loaded Q (5e5) and the available RF power is insufficient to follow the bunch phase modulation. The crabbing voltage is not modulated, causing a phase error w.r.t. the individual bunch centroids, leading to transverse kicks of the centroids and an asymmetric crabbing of the bunch cores. We present an analytical model for the resulting luminosity reduction and validate with particle tracking simulations. Due to the symmetry of the bunch filling patterns for the counter-rotating beams, the peak luminosity is reduced by only 2% for nominal HL-LHC parameters at IPs 1 and 5, which is within tolerable limits.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF034

Layout and Performance of the FCC-ee Pre-Injector Chain

linac, emittance, damping, injection

169

S. Ogur, T.K. Charles, K. Oide, Y. Papaphilippou, L. Rinolfi, F. Zimmermann
CERN, Geneva, Switzerland
A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia
I. Chaikovska, R. Chehab
LAL, Orsay, France
K. Furukawa, N. Iida, T. Kamitani, F. Miyahara
KEK, Ibaraki, Japan
E.V. Ozcan
Bogazici University, Bebek / Istanbul, Turkey
S.M. Polozov
MEPhI, Moscow, Russia

The Future Circular e⁺e⁻ Collider pre-injector chain consists of a 6 GeV S-Band linac, a damping ring at 1.54 GeV and pre-booster ring to reach 20 GeV for injection to the main booster. The electron and positron beams use the same accelerator chain alternatively. The e⁺ beam is generated from a novel low level RF-gun providing 6.5 nC charge at 11 MeV with 0.5 micron geometric emittance. The e⁺ beam is produced by the impact of a 4.46 GeV e^- beam onto a hybrid target, accelerated in the linac up to 1.54 GeV, and injected to the damping ring for emittance cooling. Simulations on the performance of the DR are presented for reaching the required equilibrium emittances at the required damping time. As an alternative option, a 20 GeV linac is considered utilising C-Band cavities and simulations studies have been undertaken regarding the beam transport and transmission efficiency up to that energy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF036

FCC-ee Hybrid RF Scheme

HOM, impedance, operation, radiation

173

Sh. Gorgi Zadeh, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
R. Calaga, F. Gerigk
CERN, Geneva, Switzerland

Funding: Research supported by the FCC design study
For FCC-ee, the range of beam energies and beam currents is large between each mode of operation, all scaled to an available 50 MW maximum power per beam. The two limiting scenarios for the RF system design are at low energy (45 GeV) with high beam current (1.45 A) and the highest energy (182.5 GeV) with a radiation loss reaching 8.92 GeV per turn. In this paper, RF staging with a hybrid scheme using both 400 MHz and 800 MHz is proposed to mitigate the requirements on the two extremes. Relevant comparisons are made with respect to using only a single frequency for all modes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF036

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF042

Crab Cavity Failures Combined with a Loss of the Beam-Beam Kick in the High Luminosity LHC

beam-losses, luminosity, dumping, collimation

192

B. Lindstrom, H. Burkhardt, V.K.B. Olsen, A. Santamaría García, K.N. Sjobak, M. Valette, D. Wollmann
CERN, Geneva, Switzerland

Crab cavities are an essential component of the High Luminosity LHC (HL-LHC) project. In case of a failure they can create large transverse kicks on the beam within tens of microseconds and, therefore, require a fast extraction of the circulating beam. In this paper, the effects of different crab cavity failures in combination with the missing beam-beam kick following the dump of only one LHC beam are presented and consequences for the interlocking strategy of crab cavities are discussed.
Work supported by the High Luminosity LHC project.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF061

Emittance Growth in Coast in the SPS at CERN

emittance, scattering, experiment, feedback

257

F. Antoniou, H. Bartosik, T. Bohl, R. Calaga, L.R. Carver, J. Repond, G. Vandoni
CERN, Geneva, Switzerland
A. Alekou
UMAN, Manchester, United Kingdom

Funding: Research supported by the HL-LHC project.
The HL-LHC prototype crab-cavities are installed in the CERN SPS, which will allow for a comprehensive beam test with high energy protons for the first time. As the time available for experimental beam dynamics studies with the crab cavities installed in the machine will be limited, a very good preparation is required. One of the main concerns is the induced emittance growth, driven by phase amplitude jitter in the crab cavities. In this respect, several machine development (MD) studies were performed during the past years to quantify and characterize the long term emittance evolution of proton beams in the SPS. In these proceedings, the experimental observations from past years are summarized and the MD studies from 2016 and 2017 are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF061

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF076

Energy Spread Compensation in Arbitrary Format Multi-Bunch Acceleration With Standing Wave and Traveling Wave Accelerators

beam-loading, acceleration, positron, linac

307

M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan

In the E-driven ILC (International Linear Collider) positron source, the beam is generated and accelerated in a multi-bunch format with mini-trains. The macro-pulse contains 2 to 8 mini-trains with several train gaps, because the pulse format is a copy of a part of the bunch storage pattern in DR (Damping Ring). This pulse format causes a variation of the accelerator field in the pulse due to the transient beam loading and an intensity fluctuation of captured positron. In this article, we discuss the compensation of the energy spread of such beam in standing wave and traveling wave accelerators. For standing wave accelerator, it can be compensated by switching input RF at appropriate timings. For traveling wave accelerator, it can be compensated by amplitude modulation of the input RF.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF076

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF077

A Design Study of the Electron-driven ILC Positron Source Including Beam Loading Effect

positron, beam-loading, acceleration, booster

311

H. Nagoshi, M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
K. Negishi
Iwate University, Morioka, Iwate, Japan
T. Omori, M. Satoh, Y. Seimiya, J. Urakawa
KEK, Ibaraki, Japan
Y. Sumitomo
LEBRA, Funabashi, Japan
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

The International Linear Collider (ILC) is a next-generation accelerator for high-energy physics to study the Higgs and top sector in the Standard Model, and new physics such as supersymmetry and dark matter. ILC positron source based on Electron-driven method has been proposed as a reliable technical backup. In this article, we report the design study of the positron source based on the off-the-shelf RF components. The positron is generated and accelerated in a multi-bunch format. To compensate the energy variation by the transient beam loading effect, we employ AM (Amplitude Modulation) technique and the results were 16.60 ± 0.14 MV (peak-to-peak) for L-band 2m cavity driven by 22.5 MW power and 25.76 ± 0.19 MV (peak-to-peak) for S-band 2m ac-celerator driven by 36 MW power with 0.78 A beam load-ing.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF077

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK001

Optics for RF Acceleration Section for the High Energy Large Hadron Collider

optics, quadrupole, dipole, instrumentation

345

L. van Riesen-Haupt, J.L. Abelleira
University of Oxford, Oxford, United Kingdom
J.L. Abelleira, E. Cruz Alaniz, P. Martinez Mirave, A. Seryi
JAI, Oxford, United Kingdom
M. Hofer, F. Zimmermann
CERN, Geneva, Switzerland
D. Zhou
KEK, Ibaraki, Japan

Funding: Work supported by the Horizon 2020 project EuroCirCol, grant 654305 and by the Science and Technology Facilities Council
As part of the FCC study, the design of the High Energy LHC (HE-LHC) is addressed. A proposed layout for the interaction region for the containing the radio frequency (RF) cavities and various beam instrumentation will be discussed. The higher energy requires more RF cavities, which strongly restricts the space available for optics and instrumentation. Another challenge arises because the beam rigidity increases whilst the LHC geometry has to be conserved. To this end, next generation dipoles have to be used in order to achieve sufficient beam to beam separation. A design that provides enough beam stay clear (BSC) in all the magnets will be presented. The design introduces an additional quadrupole on either side of the RF region to be used for phase advance adjustments that can increase the dynamic aperture.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK001

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK005

HE-LHC Final Focus: Flat Beam Parameters and Energy Deposition Studies

optics, luminosity, quadrupole, dipole

356

J.L. Abelleira, E. Cruz Alaniz, A. Seryi, L. van Riesen-Haupt
JAI, Oxford, United Kingdom
J.L. Abelleira, E. Cruz Alaniz, L. van Riesen-Haupt
University of Oxford, Oxford, United Kingdom

Funding: Work supported by EuroCircol, EU's Horizon 2020 grant No 654305 & STFC grant to the John Adams Institute
The High Energy LHC (HE-LHC) project is studying the feasibility of a new proton-proton collider with a beam energy of 13.5 TeV. The nominal optics features a β^* of 0.25 m and crab-cavities. Here we present a flat-beam optics that can be used with a non-zero crossing angle, in the absence of crab cavities. This is followed by energy deposition studies for the superconducting quadrupoles and dipole separators. The total dose in these magnets coming from the collision debris is evaluated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK005

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK010

Study Progress of the Coupling Resonance of the Crab Crossing Scheme in Electron-Ion Collider

luminosity, electron, synchrotron, simulation

368

Y. Hao
FRIB, East Lansing, USA
Y. Luo, V. Ptitsyn
BNL, Upton, Long Island, New York, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Crab crossing scheme is essential collision scheme to achieve high luminosity for the future electron-ion collider (EIC). The bunch length effect of the ion beam cannot be ignored even when cooling is present compared with the wavelength of the crab cavity, therefore, the nonlinear dependence of the crabbing kick may present a challenge to the beam dynamics of the ion beam, hence an impact to the luminosity lifetime. In this paper, we present the result of numerical beam dynamics studies of the crab crossing scheme. The result indicates that there is a special coupling resonance in the nonlinear relation of the crab crossing scheme of the EIC, which dominates the luminosity degradation. And we will discuss the possible remedies for such resonance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK017

Transient Beam Loading Due to the Bunch Train Gap and Its Compensation Experiments at BEPC-II and ALS

experiment, feedback, beam-loading, luminosity

390

H. Wang, R.A. Rimmer, S. Wang
JLab, Newport News, Virginia, USA
J.P. Dai, Q. Qin, J. Xing, J.H. Yue, Y. Zhang
IHEP, Beijing, People's Republic of China
D. Teytelman
Dimtel, San Jose, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Non-uniform bunch fill patterns in storage rings, driven by the need to provide gaps for beam aborting and ion clearing cause a large beam loading change in the RF cavities. The induced turn-periodic transient in the cavity voltage modulates longitudinal beam properties along the train, such as synchronous position and bunch length. In the EIC design, due to the asymmetric bunch train structure between the electron and the ion beam, such modulation results in shifting collision point and leads to reduced luminosity. We have carried out the beam based experiments at BEPC-II and ALS using bunch-by-bunch diagnostic capabilities of the coupled-bunch feedback systems to study this transient effect. A modulated bunch filling pattern with higher charge density around the gap has been demonstrated to be effective in partially compensating this transient modulation. Details of the experimental setups and the data analysis will be presented to this conference.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK017

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML009

New High Luminosity LHC Baseline and Performance at Ultimate Energy

operation, luminosity, optics, emittance

408

L.E. Medina Medrano
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
A. Apollonio, G. Arduini, O.S. Brüning, M. Giovannozzi, L.E. Medina Medrano, S. Papadopoulou, Y. Papaphilippou, S. Redaelli, R. Tomás
CERN, Geneva, Switzerland

Funding: Research supported by the HL-LHC project and the Beam project (CONACYT, Mexico).
The LHC machine is envisioned to operate eventually at an ultimate beam energy of 7.5 TeV at the end of LHC Run 4, i.e. after commissioning of the HL-LHC systems, a stage falling into the High Luminosity LHC (HL-LHC) era. In this paper we review the latest baseline parameters and performance, and study the potential reach of the HL-LHC with pushed optics at the ultimate beam energy. Results in terms of integrated luminosity and effective pile-up density of both the nominal (5.0×10³⁴ cm^-2 s⁻¹) and ultimate (7.5×10³⁴ cm^-2 s⁻¹) levelling operations are discussed

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML009

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML015

Simulations and Measurements of the CCL Modules of the LIGHT Accelerator

coupling, linac, proton, GUI

429

V. F. Khan, G. De Michele, S. Fanella, S. H. Gibson, Ye. Ivanisenko, C. Mellace, J.L. Navarro Quirante, C. Zannini
AVO-ADAM, Meyrin, Switzerland
M. Esposito, P. Gradassi
CERN, Geneva, Switzerland

A 230 MeV proton LINAC system for medical applications is being developed and commissioned for the LIGHT (Linac Image Guided Hadron Therapy) project by AVO-ADAM. The LINAC system consists of a 750 MHz RFQ (Radio frequency quadrupole) for the low energy proton acceleration, 2998 MHz SCDTL (Side Coupled Drift Tube Linacs) for the medium energy and 2998 MHz CCL (Coupled Cavity Linacs) for the high energy. In particular, the CCL accelerating modules are used in the energy range from 37.5 - 230 MeV. In this paper we discuss the 3D EM (electro-magnetic) simulation results and measurements of the CCL modules.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML017

Status and Development of the MYRRHA Injector

diagnostics, linac, MMI, rfq

432

D. Mäder, H. Höltermann, D. Koser, B. Koubek, K. Kümpel, P. Müller, U. Ratzinger, M. Schwarz, W. Schweizer
BEVATECH, Frankfurt, Germany
C. Angulo, J. Belmans, D. Davin, W. De Cock, P. Della Faille, F. Doucet, A. Gatera, Pompon, F.F. Pompon, D. Vandeplassche
Studiecentrum voor Kernenergie - Centre d'Étude de l'énergie Nucléaire (SCK•CEN), Mol, Belgium
M. Busch, H. Hähnel, H. Podlech
IAP, Frankfurt am Main, Germany

The MYRRHA project aims at coupling a cw 600 MeV, 4 mA proton linac with a sub-critical reactor as the very first prototype nuclear reactor to be driven by a particle accelerator (ADS). Among several applications, MYRRHA main objective is to demonstrate the principle of partitioning and transmutation (P&T) as a viable solution to drastically reduce the radiotoxicity of long-life nuclear waste. For this purpose, the linac needs an unprecedented level of reliability in terms of allowable beam trips. The normal conducting injector delivers 16.6 MeV protons to the superconducting main linac. The first section of the injector (up to 5.9 MeV) consists of an ECR source, a 4-Rod-RFQ and a rebunching line followed by 7 individual CH-type cavities. This entire section will be set up and operated by SCK·CEN in Louvain-la-Neuve, Belgium, for ample performance and reliability testing. The first CH cavity has been sent for power tests to IAP Frankfurt, Germany. The most recent status of all cavities, couplers and the beam diagnostics of the MYRRHA injector is presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML017

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML034

Development Status of Superconducting RF Transmission Electron Microscope

acceleration, LLRF, gun, SRF

481

N. Higashi, A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, F. Qiu, M. Yamamoto
KEK, Ibaraki, Japan
S. Yamashita
University of Tokyo, Tokyo, Japan

Now we are developing a new type of transmission electron microscope (TEM) employing the accelerator technologies. In place of a DC thermal gun generally used in conventional TEMs, we apply a photocathode gun and a special-shaped superconducting cavity, named two-mode cavity. The two-mode cavity has two resonant modes of TM010 (1.3 GHz) and TM020 (2.6 GHz). To superimpose these, we can suppress the increase of the energy spread, which is needed for the high-spatial-resolution TEMs. We have already developed some prototypes of the photocathode gun and two-mode cavity, and now in the middle of the performance tests. In this presentation, we will show the latest status of the development.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML043

High Gradient Performance of an S-Band Backward Traveling Wave Accelerating Structure for Medical Hadron Therapy Accelerators

linac, proton, radiation, accelerating-gradient

491

A. Vnuchenko, C. Blanch Gutiérrez, D. Esperante Pereira
IFIC, Valencia, Spain
S. Benedetti, N. Catalán Lasheras, A. Grudiev, B. Koubek, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch
CERN, Geneva, Switzerland
A. Faus-Golfe
LAL, Orsay, France
T.G. Lucas, M. Volpi
The University of Melbourne, Melbourne, Victoria, Australia
S. Pitman
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

The high-gradient performance of an accelerating structure prototype for a medical proton linac is presented. The structure was designed and built using technology developed by the CLIC collaboration and the target application is the TULIP (Turning Linac for Proton therapy) proposal developed by the TERA foundation. The special feature of this design is to produce gradient of more than 50 MV /m in low-β accelerating structures (v/c=0.38). The structure was tested in an S-band test stand at CERN. During the tests, the structure reached over above 60 MV/m at 1.2 μs pulse length and breakdown rate of about 5x10^-6 bpp. The results presented include ultimate performance, long term behaviour and measurements that can guide future optimization.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML043

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML052

The Path to Compact, Efficient Solid-State Transistor-Driven Accelerators

electron, linac, impedance, simulation

520

D.C. Nguyen, C.E. Buechler, G.E. Dale, R.L. Fleming, M.A. Holloway, J.W. Lewellen, D. Patrick
LANL, Los Alamos, New Mexico, USA
V.A. Dolgashev, E.N. Jongewaard, E.A. Nanni, J. Neilson, A.V. Sy, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: Research presented in this work is supported by (LANL) Laboratory Directed Research and Development 20170521ER and by (SLAC) Department of Energy contract DE-AC02-76SF00515.
Small, lightweight, few-MeV electron accelerators that can operate with low-voltage power sources, e.g., solid-state transistors running on 50 VDC, instead of high-voltage klystrons, will provide a new tool to enhance existing applications of accelerators as well as to initiate new ones. Recent advances in gallium nitride (GaN) semiconductor technologies * have resulted in a new class of high-power RF solid-state devices called high-electron mobility transistors (HEMTs). These HEMTs are capable of generating a few hundred watts at S-, C- and X-bands at 10% duty factor. We have characterized a number of GaN HEMTs and verified they have suitable RF characteristics to power accelerator cavities **. We have measured energy gain as a function of RF power in a single low-beta C-band cavity. The HEMT powered RF accelerators will be compact and efficient, and they can operate off the low-voltage DC power buses or batteries. These all-solid-state accelerators are also more robust, less likely to fail, and are easier to maintain and operate. In this poster, we present the design of a low-beta, 5.1-GHz cavity and beam dynamics simulations showing continuous energy gain in a ten-cavity C-band prototype.
* See for example, http://www.wolfspeed.com/downloads/dl/file/id/463/product/174/cghv59350.pdf
** J.W. Lewellen et al., Proceedings of LINAC2016, Paper MO3A03

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML052

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUXGBF2

Higher-Order-Mode Effects in Tesla-Type Superconducting RF Cavities on Electron Beam Quality

HOM, FEL, electron, detector

612

A.H. Lumpkin, N. Eddy, D.R. Edstrom, P.S. Prieto, J. Ruan, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
K. Bishofberger, B.E. Carlsten
LANL, Los Alamos, New Mexico, USA
O. Napoly
CEA/DSM/IRFU, France

Funding: *Work at Fermilab supported by FRA, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Dept. of Energy. **Work at LANL supported by U.S. Dept. of Energy through the LANL/LDRD Program.
We report the direct observations of the correlation of higher order modes (HOMs) generated by off-axis electron beam steering in TESLA-type SCRF cavities and sub-macropulse beam centroid shifts (with the concomitant effect on averaged beam size and emittance). The experiments were performed at the Fermilab Accelerator Science and Technology (FAST) facility using its unique configuration of a PC rf gun injecting beam into two separated 9-cell cavities in series with corrector magnets and beam position monitors (BPMs) located before, between, and after them. The ~100-kHz oscillations with up to 300-μm amplitudes at downstream locations were observed in a 3-MHz micropulse repetition rate beam with charges of 500 and 1000 pC/b, although the effects were much reduced at 100 pC/b. The studies were based on HOM detector circuitry targeting the first and second dipole passbands, rf BPM bunch-by-bunch data, and imaging cameras viewing multi-slit images for emittance assessments at 33 MeV. Initial calculations reproduced a key feature of the phenomena. In principle, these results may be scaled to cryomodule configurations of major accelerator facilities.

Slides TUXGBF2 [3.631 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBF2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUYGBF4

Design and Simulation Tools for the High-Intensity Industrial Rhodotron Electron Accelerator

dipole, gun, electron, cathode

651

W.J.G.M. Kleeven, M. Abs, J. Brison, E. Forton, J. M. Hubert, J. Walle
IBA, Louvain-la-Neuve, Belgium

The Rhodotron is a compact industrial CW recirculating electron accelerator producing intense beams with energies in the range from about 1 to 10 MeV. RF-frequencies are in the range of 100 to 400 MHz. Average beam powers can range from 10 kW to almost 1 MW, depending of the specific type of Rhodotron. Main industrial applications are polymer cross-linking, sterilization, food treatment and container security scanning. Recently, RF pulsing was developed to reduce the average wall power dissipation, thus reducing drastically the energy consumption. Pulsing also permits smaller cavities and higher energies up to 40 MeV, opening the way to applications such as mobile irradiators, or isotopes production by photonuclear reactions, thus offering a compact and high beam duty alternative to linacs. This paper concentrates on some crucial design tools and methods for transverse and longitudinal optics studies, particle tracking with space charge, beam formation studies in the electron gun and dipole magnet design.

Slides TUYGBF4 [11.952 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBF4

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF001

Requirements for the Cryogenic Refrigerator and the He Distribution System for the MYRRHA 100 Mev Accelerator

linac, cryogenics, cryomodule, operation

655

T. Junquera
Accelerators and Cryogenic Systems, Orsay, France
C. Angulo
Studiecentrum voor Kernenergie - Centre d'Étude de l'énergie Nucléaire (SCK•CEN), Mol, Belgium
D. Vandeplassche
SCK•CEN, Mol, Belgium

MYRRHA is an ADS demonstrator for the long-lived radioactive waste transmutation. It is composed of a High Energy CW Linac Accelerator (600 MeV - 4mA) coupled to a Subcritical Reactor of 100 MW thermal power. The main challenge of the Linac is a very high reliability performance to limit stress and long restart procedures of the reactor. Within the MYRRHA project phased approach for the construction, a 100 MeV-4 mA Linac (Injector up to 17 MeV and SC Linac between 17 MeV and 100 MeV) will be constructed in the Phase 1, covering 2016-2024. The SC Linac is composed of 58 Single-Spoke SC cavities, housed in 29 cryomodules. The cavities operates at 352 MHz, in a superfluid Helium bath at 2K. In this paper, the requirements for the Linac Cryogenic System are presented. The analysis of high thermal loads induced by the CW mode operation of cavities, leads to a Cryogenic Refrigerator with a power of 2700 W (equiv. power capacity at 4.5 K). Each cryomodule is connected through a dedicated Valve Box to the Helium transfer line running along the Linac tunnel. A description of the cryogenic system features and initial models of the tunnel and associated buildings are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF001

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF003

Integrated Prototyping in View of the 100 MeV Linac for Myrrha Phase 1

linac, cryomodule, controls, target

661

D. Vandeplassche, J. Belmans
SCK•CEN, Mol, Belgium
C. Angulo, D. Davin, W. De Cock, P. Della Faille, F. Doucet, A. Gatera, Pompon, F.F. Pompon
Studiecentrum voor Kernenergie - Centre d'Étude de l'énergie Nucléaire (SCK•CEN), Mol, Belgium
D. Bondoux, F. Bouly
LPSC, Grenoble Cedex, France
H. Höltermann, D. Mäder
BEVATECH, Frankfurt, Germany
C. Joly, G. Olry, H. Saugnac
IPN, Orsay, France
M. Loiselet, N. Postiau, L. Standaert
UCL, Louvain-la-Neuve, Belgium
H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany

Funding: Work partially supported by the European Commission H2020 programme MYRTE #662186
The MYRRHA project borne by SCK•CEN, the Belgian Nuclear Research Centre, aims at realizing a pre-industrial Accelerator Driven System (ADS) for exploring the transmutation of long lived nuclear waste. The linac for this ADS will be a High Power Proton Accelerator delivering 2.4 MW CW beam at 600 MeV. It has to satisfy stringent requirements for reliability and availability: a beam-MTBF of 250h is targeted. The reliability goal is pursued through a phased approach. During Phase 1, expected till 2024, the MYRRHA linac up to 100 MeV will be constructed. It will allow to evaluate the reliability potential of the 600 MeV linac. It will also feed a Proton Target Facility in which radioisotopes of interest will be collected through an ISOL system. This contribution will focus on the transition to integrated prototyping, which will emphasize (i) a test platform consisting of the initial section of the normal conducting injector (5.9 MeV), (ii) the realization of a complete cryomodule for the superconducting linac and of its cryogenic valve box. The cryomodule will house two 352 MHz single spoke cavities operated at 2K.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF011

Btrain Calibration with RF-Master Method

dipole, synchrotron, injection, pick-up

679

L. Falbo, E. Bressi, M. Pezzetta, C. Priano
CNAO Foundation, Milan, Italy

CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. It is based on a synchrotron with a 77 m ring equipped with 16 normal conducting dipoles characterized by a long delay in the field stabilization. B-Train system is a fundamental device of the whole machine; it is used in feedback to the dipole power supply in order to regulate the magnetic field reducing the natural stabilization times that would cause long treatments. B-Train system allows to obtain the magnetic field starting from measurements of magnetic field changes: it works as an integrator and then it needs a system to reset the counts compensating the electronic and numerical drift of the system itself. An innovative method has been implemented at CNAO to reset Btrain counts exploiting beam measurements after the RF cavity trapping. This procedure has the advantage to avoid external and additional element like NMR probes. The paper shows the use of B-train system at CNAO and its calibration with this method, called "RF-master method".

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF012

Commissioning of the Lipac Medium Energy Beam Transport Line

vacuum, rfq, controls, operation

683

I. Podadera, J. Castellanos, J.M. García, D. Gavela, A. Ibarra, D. Jiménez-Rey, A. Marqueta, L.M. Martinez Fresno, E. Molina Marinas, J. Mollá, P. Méndez, C. Oliver, D. Regidor, F. Toral, R. Varela, V. Villamayor, M. Weber, C. de la Morena
CIEMAT, Madrid, Spain
P. Cara, A. Marqueta, I. Moya
Fusion for Energy, Garching, Germany
T. Ebisawa, Y. Hirata, A. Ihara, Y. Ikeda, A. Kasugai, T. Kitano, K. Kondo, T. Narita, K. Sakamoto, T. Shinya, M. Sugimoto
QST, Aomori, Japan
D. Gex, A. Jokinen
F4E, Germany
J. Knaster
IFMIF/EVEDA, Rokkasho, Japan
M. Mendez Macias
7S, Peligros (Granada), Spain
O. Nomen
IREC, Sant Adria del Besos, Spain
G. Pruneri
Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy
F. Scantamburlo
INFN/LNL, Legnaro (PD), Italy

Funding: This work has been funded by the Spanish Ministry of Economy and Competitiveness under the Agreement as published in BOE, 16/01/2013, page 1988 and the project FIS2013-40860-R.
LIPAc* will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology to be used as neutron source of the IFMIF facility. Those facilities are essential for future fusion reactors material research. A 175 MHz RFQ will increase the energy up to 5 MeV before a Superconducting RF (SRF) linac with eight 175 MHz Half Wave Resonators brings the particles up to the final energy of 9 MeV. Between both stages, a Medium Energy Beam Transport line (MEBT)** aims at transporting and matching the beam between the RFQ and the SRF linac. The transverse focusing of the beam is controlled by five quadrupole magnets with integrated steerers, grouped in one triplet and one doublet. Two buncher cavities handle the longitudinal dynamics. Two movable scraper systems are included to purify the beam optics coming out the RFQ and avoid losses in the SRF linac. In this contribution, checkout of the beamline and its ancillaries in Japan is reported. Tests carried out on the beamline prior to the MEBT beam commissioning are described, focusing in vacuum tests, magnets powering, buncher conditioning and scrapers movement.
* P. Cara et al., IPAC16, MOPOY057 , p.985, Busan, Korea (2016)
** I. Podadera et al., LINAC2016, TUPLR041, p.554, East Lansing, USA (2016).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF014

Beam Dynamics Studies For the IFMIF-DONES SRF-Linac

linac, SRF, cryomodule, solenoid

687

L. Du, N. Bazin, N. Chauvin, S. Chel, J. Plouin
CEA/IRFU, Gif-sur-Yvette, France

The DONES (DEMO oriented neutron source) project is aimed at constructing a DEMO of IFMIF to provide sufficient material damage [1]. In the SRF-Linac of this project, losses can cause harmful material activation and must be maintained much less than 1W/m. It's a challenge to keep losses at such a low level with high beam power and high space charge. This paper presents two designs of the DONES SRF-Linac, one with 4 cryomodules and another with 5 cryomodules. The design details to reduce the losses and the multi-particle simulation results will be shown. The errors studies for these results will also be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF014

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF015

Preliminary Test Results of the First ESS Elliptical Cryomodule Demonstrator

cryomodule, cryogenics, vacuum, radiation

691

F. Peauger, C. Arcambal, S. Berry, P. Bosland, E. Cenni, G. Devanz, T. Hamelin, O. Piquet, B. Renard, P. Sahuquet, T. Trublet
CEA/DRF/IRFU, Gif-sur-Yvette, France
C. Darve
ESS, Lund, Sweden
P. Michelato
INFN/LASA, Segrate (MI), Italy
G. Olivier
IPN, Orsay, France
J.P. Thermeau
Laboratoire APC, Paris, France

Two ESS elliptical cavities cryomodule prototypes are being developed and will be tested at CEA Saclay before starting the series production. This paper presents the preliminary test results of the first medium beta cavities cryomodule demonstrator M-ECCTD. The measurements of the cryogenic performances at 80 K and 2 K of the different cryomodule components and circuits are given. The first RF test results performed at low power are also reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF026

Higher-Harmonic RF System for Landau Damping in the CERN PS

damping, flattop, dipole, synchrotron

728

H. Damerau, A. Lasheen, E.N. Shaposhnikova
CERN, Geneva, Switzerland

Longitudinal coupled-bunch instabilities after transition crossing and at the flat-top limit the intensity of LHC-type beams in the CERN Proton Synchrotron (PS). A dedicated coupled-bunch feedback for dipole oscillation modes, using a Finemet cavity as wide-band longitudinal kicker, suppresses the instabilities up to an intensity of about 2·10¹¹ particles per bunch at extraction. However, dipole and quadrupole coupled-bunch oscillations are observed beyond this intensity. At the flat-top they were damped with a 40 MHz RF cavity operated as a higher-harmonic RF system to increase Landau damping, in addition to the principal RF system at 10 MHz. The existing 40 MHz RF system, designed for RF manipulations at fixed frequency, does not cover the frequency range required during acceleration. It is therefore proposed to install a tunable RF system with a 5% relative frequency swing. This paper summarizes the observations of instability damping at the flat-top and presents preliminary parameters for the higher-harmonic RF system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF026

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF034

LEIR Injection Efficiency Studies as a Function of the Beam Energy Distribution from Linac3

linac, injection, bunching, optics

758

S. Hirlaender, R. Alemany-Fernández, H. Bartosik, G. Bellodi, N. Biancacci, V. Kain, R. Scrivens
CERN, Geneva, Switzerland

High intensities in the CERN Low Energy Ion Ring (LEIR) are achieved using multi-turn injections from the pre-accelerator Linac3 combined with simultaneous stacking in momentum and transverse phase spaces. Up to seven consecutive 200 μs long, 200 ms spaced pulses are injected from Linac3 into LEIR by stacking each of them into the six-dimensional phase-space over 70 turns. An inclined septum magnet allows proper filling of the transverse phase-space plane, while longitudinal stacking requires momentum variation achieved by a shift of mean momentum over time provided by phase shifting a combination of 2 RF cavities at the exit of Linac3. The achievable maximum accumulated intensity depends strongly on the longitudinal beam quality of the injected beam. The longitudinal Schottky signal is used to measure the received energy distribution of the circulating beam which is then correlated with the obtained injection efficiency. This paper presents the experimental studies to understand and further improve the injection reliability and the longitudinal stacking.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF042

Characterization of the Beam Energy Spread at the REX/HIE-ISOLDE Linac

ISOL, linac, experiment, detector

787

M.L. Lozano, N. Bidault, E. Fadakis, M.A. Fraser, E. Matli, J.A. Rodriguez
CERN, Geneva, Switzerland

ISOLDE is an on-line radioactive isotope separator located at CERN that works by colliding protons accelerated in the PS Booster into a fixed target and by separating the resultant ionized isotopes using a magnetic separator. The completion of the HIE-ISOLDE superconducting linac allows the acceleration of these ions to energy levels that were not reachable before, opening the door to new experiments in different fields. These experiments often have special requirements in terms of beam intensity and purity, transverse emittance or energy spread. A possible way to reduce the energy spread of the beam delivered to the experimental stations is to use one or more of the superconducting cavities as bunchers. The main results of several tests conducted during the last beam commissioning campaign prove that this mode of operation is feasible and will be presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF057

The SPS Tests of the HL-LHC Crab Cavities

cryomodule, vacuum, HOM, operation

846

R. Calaga, O. Capatina, G. Vandoni
CERN, Geneva, Switzerland

Funding: Research supported by the HL-LHC project
Two superconducting crab cavities in the framework of the High Luminosity (HL-LHC) LHC were built to test for the first time with proton beams in the Super Proton Synchrotron (SPS) at CERN. These tests will address the operation of the crab cavities in a high current and high intensity proton machine through the full energy cycle with a primary focus on cavity transparency, performance and stability, failures modes and long term effects on proton beams. An overview of the SPS cryomodule development towards the SPS tests along with the first test results are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF057

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF063

Beam Dynamics Studies of the ESS LINAC Using a New Multicell Cavity Model

linac, emittance, DTL, distributed

870

R. De Prisco, D.C. Plostinar
ESS, Lund, Sweden

The European Spallation Source is designed to deliver 5 MW proton beam power on the target while keeping the beam induced losses below 1 W/m throughout the LINAC. This implies the need of accurate models to correctly describe the longitudinal beam dynamics within the multi-cell cavities. In all the previous error studies the cells of a multi-cell cavity were modelled as a sequence of independent gaps and the errors were applied directly on the amplitude of each cell accelerating field, considered as random variable. In this paper, instead, we present a new detailed analysis of the effect of the error tolerances on the beam dynamics including a new model to calculate the amplitude errors of the accelerating field in the multi-cell cavities: errors are applied on the geometrical parameters of each cavity; then the accelerating field is calculated solving the Maxwell equations over all the cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF063

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF068

Functional Integration of the RFQ in the ESS Systems

rfq, controls, LLRF, vacuum

890

J.S. Schmidt, E. Bargalló, T. Fay, G. Hulla, B. Lagoguez, R. Montaño, E. Sargsyan, S. Scolari, H. Spoelstra
ESS, Lund, Sweden
A.C. Chauveau, M. Desmons, O. Piquet
CEA/IRFU, Gif-sur-Yvette, France
A.J. Johansson
Lund University, Lund, Sweden
W. Ledda
Vitrociset s.p.a, Roma, Italy

The 352 MHz Radio Frequency Quadrupole (RFQ) for the European Spallation Source ERIC (ESS) will be delivered during 2018. After delivery, installation and tuning of the cavity, the high power RF conditioning will be performed. At this point all the different systems that are needed to condition and operate the RFQ have to be in place and operational. This paper will give an overview of the system analysis that has been performed for the RFQ. The RFQ requirements for the RF system, including the RF distribution system (RFDS), the Low Level RF (LLRF) and the local RF protection system (RFLPS) will be presented. In addition, the paper covers the system integration of the structure in the ESS control and vacuum systems as well as the outcome of a machine protection analysis.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF068

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF079

Scaled Alvarez-Cavity Model Investigations for the UNILAC Upgrade

DTL, simulation, alignment, pick-up

916

M. Heilmann, X. Du, L. Groening, M. Kaiser, S. Mickat, M. Vossberg
GSI, Darmstadt, Germany
A. Seibel
IAP, Frankfurt am Main, Germany

The 1:3 scaled aluminum model of an Alvarez-type cavity with 10 gaps was used for comparison of simulation with measurement for the frequency and the electric field on axis. The scaled frequency is 325.224 MHz and an Alvarez cavity has a small frequency tuning range. With this scaled model it was possible to apply different stem configurations for each drift tube to damp parasitic modes and to increase the field stability. The new drift tubes have an optimized free-formed profile on the end plates in order to increase the shunt impedance. In special the assembly, positioning and alignment of the drift tubes can be tested and the frequency change can be investigated in this respect.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF079

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF080

Final Design of the FoS Alvarez-Cavity-Section for the Upgraded UNILAC

DTL, quadrupole, operation, simulation

920

M. Heilmann, X. Du, L. Groening, M. Kaiser, S. Mickat, C. Mühle, A. Rubin, V. Srinivasan
GSI, Darmstadt, Germany
A. Seibel
IAP, Frankfurt am Main, Germany

The final design describes the First-of-Series (FoS) Alvarez-Cavity-section of the first tank being part of the new post-stripper DTL of the UNILAC. The FoS-cavity has an input energy of 1.358 MeV/u with 11 drift tubes (including quadrupole singlets) in a total length of 1.9 m and a diameter of 2 m with an operation frequency of 10⁸.4 MHz. The drift tubes will have a new shape profile at the end plates. The single layered quadruple singlets inside the drift tubes are pulsed with 10 Hz and will have a maximum field gradient of 51 T/m. The new drift tube design combines the new shape profile with the transverse and longitudinal installation space of the magnet. The FoS Alvarez-cavity will be part of the first section of the new Alvarez DTL. It shall be operated at nominal RF- and magnetic fields prior to procurement of the series.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF080

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF088

Final factory-side Measurements of the Next SC CH-Cavities for the HELIAC-Project

linac, resonance, heavy-ion, factory

943

M. Basten, M. Busch, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany
K. Aulenbacher, W.A. Barth, V. Gettmann, T. Kürzeder, M. Miski-Oglu
HIM, Mainz, Germany
W.A. Barth, F.D. Dziuba, M. Heilmann, S. Yaramyshev
GSI, Darmstadt, Germany

Funding: Work supported by the EU Framework Programme H2020 662186 (MYRTE); Work supported by BMBF Contr. No. 05P15RFBA;
The upcoming FAIR project (Facility for Antiproton and Ion Research) at GSI will use the existing UNILAC (UNIversal Linear Accelerator) as an injector to provide high intensity heavy ion beams at low repetition rates. As a consequence a new superconducting (sc) continous wave (cw) high intensity heavy ion Linac is required to provide ion beams above the coulomb barrier to keep the Super Heavy Element (SHE) physics program at GSI competitive on an international level. The fundamental Linac design comprises a high performance ion source, the High Charge State Injector (HLI) upgraded for cw-operation and a matching line (1.4 MeV/u) followed by a sc Drift Tube Linac (DTL). Four cryo modules each equipped with three Crossbar-H-mode (CH) structures provide for acceleration up to 7.3 MeV/u. The first section of this ambitious accelerator project has been successfully commissioned and tested with heavy ion beam from the HLI in 2017. It comprises two sc 9.3 T solenoids and a sc 217 MHz CH-cavity with 15 equidistant gaps as a demonstrator. The construction of the next two sc 217 MHz 8 gap CH-cavities is nearly finished and final factory-side measurements will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF088

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK002

Advanced Approach for Beam Matching along the Multi-Cavity SC CW Linac at GSI

linac, heavy-ion, emittance, proton

955

S. Yaramyshev, W.A. Barth, M. Heilmann
GSI, Darmstadt, Germany
K. Aulenbacher
IKP, Mainz, Germany
K. Aulenbacher, W.A. Barth, V. Gettmann, T. Kürzeder, M. Miski-Oglu
HIM, Mainz, Germany
M. Basten, M. Busch, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany

A multi-stage program for the development of a heavy ion superconducting (sc) continuous wave (cw) linac is in progress at HIM (Mainz, Germany) and GSI (Darmstadt, Germany) under support of IAP (Frankfurt, Germany). In 2017 the first section of the CW-Linac has been successfully commissioned at GSI. Beam acceleration at the CW-Linac is foreseen to be performed by up to twelve multi-gap CH cavities. The linac should provide the beam for physics experiments, smoothly varying the output particle energy from 3.5 to 7.3 MeV/u, simultaneously keeping high beam quality. Due to a wide variation of the input- and output -beam energy for each cavity, a longitudinal beam matching to every cavity is of high importance. An advanced algorithm for an optimization of matched beam parameters under variable rf-voltage and rf-phase of each cavity has been developed. The description of the method and the obtained results are presented in the paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK002

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK003

Beam Dynamics Simulations for the New Superconducting CW Heavy Ion LINAC at GSI

linac, heavy-ion, cryomodule, solenoid

959

M. Schwarz, M. Basten, M. Busch, H. Podlech
IAP, Frankfurt am Main, Germany
K. Aulenbacher
IKP, Mainz, Germany
K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu
HIM, Mainz, Germany
W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev
GSI, Darmstadt, Germany

Funding: Work supported by BMBF Contr. No. 05P15RFBA and EU Framework Programme H2020 662186 (MYRTE)
For future experiments with heavy ions near the coulomb barrier within the super-heavy element (SHE) research project a multi-stage R&D program of GSI/HIM and IAP is currently in progress. It aims for developing a supercon-ducting (sc) continuous wave (CW) LINAC with multiple CH cavities as key components downstream the High Charge State Injector (HLI) at GSI. The LINAC design is challenging due to the requirement of intense beams in CW mode up to a mass-to-charge ratio of 6, while covering a broad output energy range from 3.5 to 7.3 MeV/u with unchanged minimum energy spread. Testing of the first CH-cavity in 2016 demonstrated a promising maximum accelerating gradient of E_a = 9.6 MV/m; the worldwide first beam test with this sc multi-gap CH-cavity in 2017 was a milestone in the R&D work of GSI/HIM and IAP. In the light of experience gained in this research so far, the beam dynamics layout for the entire LINAC has recently been updated and optimized.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK004

Superconducting CH-Cavity Heavy Ion Beam Testing at GSI

linac, heavy-ion, acceleration, emittance

962

W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev
GSI, Darmstadt, Germany
K. Aulenbacher
IKP, Mainz, Germany
K. Aulenbacher, F.D. Dziuba, V. Gettmann, T. Kürzeder, M. Miski-Oglu
HIM, Mainz, Germany
M. Basten, M. Busch, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany

Recently the first section of a standalone superconducting (sc) continuous wave (cw) heavy ion Linac as a demonstration of the capability of 217 MHz multi gap Crossbar H-mode structures (CH) has been commissioned and extensively tested with beam from the GSI- High Charge State Injector. The demonstrator set up reached acceleration of heavy ions up to the design beam energy and beyond. The required acceleration gain was achieved with heavy ion beams even above the design mass to charge ratio at high beam intensity and full beam transmission. This contribution presents systematic beam measurements with varying RF-amplitudes and phases of the CH-cavity, as well as versatile phase space measurements for heavy ion beams with different mass to charge ratio. The worldwide first and successful beam test with a superconducting multi gap CH-cavity is a milestone of the R&D work of Helmholtz Institute Mainz (HIM) and GSI in collaboration with Goethe University Frankfurt (GUF) in preparation of the sc cw heavy ion Linac project and other cw-ion beam applications.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK004

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK005

Upgrade Plan of J-PARC MR - Toward 1.3 MW Beam Power

operation, experiment, injection, proton

966

T. Koseki
KEK, Ibaraki, Japan

The Main Ring Synchrotron (MR), a 30-GeV slow cycling proton synchrotron, delivers intense proton beam to a long-baseline neutrino oscillation experiment, T2K, by fast extraction and to an experimental facility, which is called hadron hall by slow extraction. The achieved beam intensities for routine operations are 470 kW ( 2.4 x 10¹⁴ ppp) for the fast extraction and 44 kW ( 5.1 x 10¹³ ppp) for the slow extraction. In order to increase the beam intensity, a plan to replace the magnet power supplies are now in progress for operation with a higher repetition rate. After the replacement, the cycle time will be shortened about a half and increase beam intensities two times larger for the fast extraction. In addition, a further upgrade plan for the fast extraction is mainly reinforcement of rf power supplies. The goal of the upgrade plan is reaching 1.3 MW beam power for the neutrino experiment.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK005

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK011

Present Status and Future Upgrades of the J-PARC Ring RF Systems

proton, power-supply, operation, controls

984

M. Yoshii, M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama
KEK, Tokai, Ibaraki, Japan
M. Nomura, T. Shimada, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

J-PARC is the multipurpose research institutes. 10 years have passed since the user operation started. We have been considering the upgrades for the future and the target beam powers for 3 GeV rapid cycling synchrotron (RCS) and 30GeV Main ring (MR) are 1.5MW and 1.3MW. To achieve a 1.5MW of RCS output beam power, increasing the number of Linac proton particles is necessary. For accelerating such higher beam current, the rf systems in the RCS need to upgrade an accelerating voltage and to take account of heavier beam loading. In case of the MR, increasing the number of proton is not appropriate from the viewpoint of space charge effects. We chose to shorten the MR cycle time. The required RF voltages become almost double. All nine systems have been replaced with the higher accelerating gradient RF systems using a newly developed magnetic alloy material. At present, the proton beam of 470kW is being delivered with a cycle time of 2.48s. Beam powers of MR will plan to aim first at 750KW after replacing the magnet power supplies. But, to realize a 1.3MW beam power, upgrading the RF power sources will be necessary. We present the ring RF system status and their upgrades for the future.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK012

Conceptual Design of a Single-Ended MA Cavity for J-PARC RCS Upgrade

acceleration, operation, vacuum, power-supply

987

M. Yamamoto, M. Nomura, T. Shimada, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan

The J-PARC RCS employes Magnetic Alloy (MA) loaded cavities and rf power is fed by vacuum tubes in push-pull operation. The multi-harmonic rf driving and the multi-harmonic beam loading compensation are realized due to the broadband characteristics of the MA. However, the push-pull operation has disadvantages in the multi-harmonics. An unbalance of the anode voltage swing remarkably appears at very high intensity beam acceleration. In order to avoid the unbalance, a single-ended MA cavity is considered for the RCS beam power upgrade because no unbalance arises intrinsically. We will describe the conceptual design of the single-end MA cavity for the RCS upgrade.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAK015

The SARAF-LINAC Project 2018 Status

linac, cryomodule, status, controls

994

N. Pichoff, D. Chirpaz-Cerbat, R. Cubizolles, J. Dumas, R.D. Duperrier, G. Ferrand, B. Gastineau, P. Gastinel, F. Gougnaud, M. Jacquemet, C. Madec, Th. Plaisant, F. Senée, A. Sutra-Fourcade, D. Uriot
IRFU, CEA, University Paris-Saclay, Gif-sur-Yvette, France
D. Berkovits, J. Luner, A. Perry, E. Reinfeld, J. Rodnizki
Soreq NRC, Yavne, Israel
M. Di Giacomo
GANIL, Caen, France

SNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). CEA is in charge of the design, construction and commissioning of the MEBT line and the superconducting linac (SARAF-LINAC Project). The prototypes of the 176 MHz NC rebuncher, SC cavities, RF coupler and SC Solenoid-Package are under construction and their test stands construction or adaptation is in progress at Saclay. Meanwhile, the cryomodules and the global system just passed their Critical Design Reviews. This paper presents the status of the SARAF-LINAC Project at April 2018.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL009

Studying a Prototype of Dual-beam Drift Tube Linac

DTL, rfq, simulation, acceleration

1020

T. He, L. Lu, W. Ma, L.P. Sun, C.C. Xing, X.B. Xu, L. Yang
IMP/CAS, Lanzhou, People's Republic of China

For generating high-intensity ion beams from linear ac-celerators, a multi-beam acceleration method which in-volves multiple accelerating beams to suppress the defo-cusing force from space charge effects, then integrating these beams by a beam funneling system, has been pro-posed. An Inter-digital H-mode (IH) two-beam type radio frequency quadrupole (RFQ) with accelerating 108mA (54mA/channel×2) carbon ion from 5 to 60 keV/ u and an IH four-beam RFQ with accelerating 160.8mA (40.2mA/channel×4) carbon ion from 3.6 to 41.6 keV/u had been successfully designed for low energy heavy ion acceleration [1]. In order to demonstrate that an IH dual-beam drift tube linac (DB-DTL) is suitable for high-intensity heavy ion beam acceleration in middle energy region, we has been developing a DB-DTL prototype by using three dimensional electromagnetic CST MicroWave Studio (MWS) and using particles tracking Pi Mode Linac Orbit Calculation (PiMLOC) [2-3]. According to the simulation results, the beam dynamics design and elec-tromagnetic design will be presented in this paper.
* Shota. Iketa et al., Nucl. Instr. and Meth. in Phys. Res. B.239-243 (2017).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL009

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL011

Low Power Test and Tuning of the LEAF RFQ

rfq, quadrupole, dipole, operation

1028

L. Lu, T. He, Y. He, W. Ma, L.B. Shi, L.P. Sun, C.C. Xing, X.B. Xu, L. Yang, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China

A continuous wave (CW) four-vane radio frequency quadrupole (RFQ) accelerator is under construction for the Low Energy Accelerator Facility (LEAF) at Institute of Modern Physics (IMP). The 5.96 m RFQ will operate with the capability of accelerating all ion species from proton to uranium from 14 keV/u up to 500 keV/u. In this paper, the low power test and tuning results of the RFQ accelerator, including the test of the separate sections and the whole cavity, will be presented. After the final tuning, the relative error of the quadrupole field is within 2% and the admixture of the dipole modes are below 4% of the quadrupole mode.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL012

Design and Fabrication of Hybrid RFQ Prototype

DTL, rfq, linac, site

1032

P.Y. Yu, Y. He, C.X. Li, G.Z. Sun, F.F. Wang, Z.J. Wang, B. Zhang, T.M. Zhu
IMP/CAS, Lanzhou, People's Republic of China

Hybrid RFQ is proposed as a potential good choice at the low-energy range of linear accelerator. The complexi-ty of mechanical design and difficulty of fabrication are part of reasons impeding application of it and similar structures. In order to explore the practicable structure and research on RF parameters of this accelerating struc-ture, an aluminium prototype is developed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL022

Low-Reflection RF Window for ACS Cavity in J-PARC Linac

Windows, linac, proton, impedance

1051

J. Tamura, Y. Kondo, T. Morishita
JAEA/J-PARC, Tokai-mura, Japan
H. Ao
FRIB, East Lansing, USA
F. Naito, M. Otani
KEK, Tokai, Ibaraki, Japan
Y. Nemoto
Nippon Advanced Technology Co., Ltd., Tokai, Japan

In the Japan Proton Accelerator Research Complex (J-PARC) linac, the Annular-ring Coupled Structure (ACS) cavities have been stably operating. To maintain this operation availability, we manufactured three backups of the pillbox-type RF windows for the ACS cavities in fiscal year 2015 and 2017. It is desirable to minimize the RF reflection of the RF window to prevent standing waves from exciting between the cavity and the RF window, and not to significantly change the optimized coupling factor between the cavity and the waveguide. To realize the minimization, the relative permittivities of the ceramic disks of the RF windows were evaluated by measuring the resonant frequencies of the pillbox cavity containing the ceramic disk. On the basis of the evaluated relative permittivities, the pillbox-part lengths of the RF windows were determined. The measured Voltage Standing Wave Ratios (VSWRs) of the manufactured RF windows are just about 1.08 and these are applicable for the practical use.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL029

Harmonictron

acceleration, proton, operation, synchrotron

1063

Y. Mori
Kyoto University, Research Reactor Institute, Osaka, Japan
H. Arima, N. Ikeda, Y. Yonemura
Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka, Japan
Y. Waga
Kyushu University, Hakozaki, Japan

The possibility of high intensity hadron/lepton accelerator based on a vertical scaling FFAG with harmonic number jump acceleration, named "Harmonictron", has been proposed. The presentation gives a design example of the Harmonictron for accelerating protons from 50 MeV to 500 MeV for generation intense secondary particles such as muon, neutron etc.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL029

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL031

Errors Study of a Double-Pass Recirculating Superconducting Proton Linac

linac, proton, emittance, quadrupole

1069

Y. Tao, K. Hwang, J. Qiang
LBNL, Berkeley, California, USA

The concept of recirculating superconducting proton linac was recently proposed. Beam dynamics simulations were carried out in a double-pass recirculating proton linac using a single bunch. Although all the beam line elements should be installed following the designed values, in reality, there exist machine imperfections that will cause beam off-centering and even particle losses. In this paper, we report on the study of the static and dynamic errors from RF cavities and magnetic focusing elements in the double-pass recirculating proton linac.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL031

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL032

A Variable Field Phase-Shifter for Recirculating Proton Linacs

linac, dipole, proton, superconducting-cavity

1072

Y. Tao, J. Qiang
LBNL, Berkeley, California, USA

The recirculating superconducting proton linac that has a potential to substantially save accelerator cost was re-cently proposed. It consists of three sections to accelerate the continues-wave (CW) beam to multiple GeVs. In the first section, the beam passes the linac two times. In the second and third sections, the beam goes through the linac four and six times. A phase-shifter is needed to meet the synchronous acceleration condition for multi-pass accel-eration using the same RF cavity due to the phase slip-page of the proton beam. Here we present the design of a variable field rectangular bend phase-shifter in which the beam goes to a different path in each pass inside the mag-net to meet the synchronous condition.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL039

Commissioning of the FRIB RFQ

rfq, controls, MMI, dipole

1090

H.T. Ren, J.F. Brandon, N.K. Bultman, M.G. Konrad, H. Maniar, D.G. Morris, P. Morrison, G. Pozdeyev, X. Rao, R. Walker, S. Zhao
FRIB, East Lansing, USA

Funding: This work is supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 #wei@frib.msu.edu
The radio-frequency quadrupole (RFQ) at the Facility for Rare Isotope Beams (FRIB) is a 4-vane type cavity designed to accelerate heavy ion beams with charge states Q/A between 1/7 and 1/3 from 12 keV/u to 0.5 MeV/u. The RFQ was assembled in the FRIB tunnel in November 2016. Bead-pull measurements and tuning were performed with low RF power. The RFQ has been conditioned to 59 kW in August 2017, which is sufficient to accelerate the Key Performance Parameter (KPP) beams, Argon and Krypton. The RFQ has been successful-ly commissioned with KPP beams in CW regime in Octo-ber 2017. 40Ar⁹⁺ and 86Kr¹⁷⁺ beams were accelerated by the FRIB RFQ in the CW regime to the designed energy of 0.5 MeV/u. With the multi-harmonic buncher operation-al, the FRIB RFQ commissioning has been completed with bunched beam in February 2018. The beam trans-mission efficiency through the RFQ was in good agree-ment with PARMTEQ simulation results. The detailed results from the FRIB RFQ tuning, high power condition-ing and beam commissioning will be presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL045

Towards Operational Scalability for H⁻ Laser Assisted Charge Exchange

laser, experiment, operation, radiation

1110

S.M. Cousineau, A.V. Aleksandrov, T.V. Gorlov, Y. Liu, M.A. Plum, A. Rakhman, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA
D.E. Johnson, S. Nagaitsev
Fermilab, Batavia, Illinois, USA
M.J. Kay
UTK, Knoxville, Tennessee, USA

The experimental development of H⁻ laser assisted charge exchange, a.k.a. laser stripping, has been ongoing at the SNS accelerator since 2006 in a three-phase approach. The first two phases associated with proof-of-principle and proof-of-practicality experiments have been successfully completed and demonstrated >95% H⁻ stripping efficiency for up to 10 us. The final phase is a proof-of-scalability stage to demonstrate that the method can be deployed for realistic beam duty factors. The experimental component of this effort is centered on achieving high efficiency stripping through the use of a laser power amplification scheme to recycle the macropulse laser light at the interaction point of the H⁻ stripping. Such a recycling cavity will be necessary for any future operational laser stripping system with at least millisecond duration H⁻ pulses. A second component of the proof-of-scalability phase is to develop a conceptual design for a realistic laser stripping scheme. The status of these efforts and challenges associated with deploying the recycling cavity into the laser stripping experiment will be described in this talk.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL049

SNS Proton Power Upgrade Status

linac, scattering, proton, injection

1120

M.A. Plum, G. A. Bloom, M.S. Champion, J. Galambos, M.P. Howell, S.-H. Kim, J. Moss, B.W. Riemer, K.S. White
ORNL, Oak Ridge, Tennessee, USA
R.B. Saethre, R. W. Steffey
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. This research was supported by the DOE Office of Science, Basic Energy Science, Scientific User Facilities.
The Spallation Neutron Source (SNS) Proton Power Upgrade (PPU) project aims to double the proton accelerator beam power from 1.4 to 2.8 MW. Over the past year PPU has completed the reviews necessary for Critical Decision-1 approval. The baseline design choices are being refined, and a cost-effective approach has been identified. The beam energy will be increased by 30% and the beam current capability improved by ~50%. The sub-system improvements and anticipated schedule will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL049

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL050

Progress Work on a CW Deuteron RFQ with Magnetic Coupling Windows

rfq, experiment, coupling, Windows

1123

Q. Fu, M.J. Easton, P.P. Gan, S.L. Gao, H.P. Li, Y.R. Lu, Q.Y. Tan, Z. Wang, K. Zhu
PKU, Beijing, People's Republic of China
W.P. Dou, Y. He
IMP/CAS, Lanzhou, People's Republic of China

Funding: This work was supported by the National Basic Research Program of China (Grant No. 2014CB845503).
A new 162.5 MHz RFQ has been built for a joint 973 project between Peking University (PKU) and Institute of Modern Physics (IMP). It is designed to deliver 50-mA deuteron beams to 1 MeV in CW mode, with an inter-voltage of 60 kV and a length of 1.809 m. Due to its window-type structure, the RFQ has compact cross-section, sufficient mode separation and high specific shunt impedance. It consists of two segments fabricated and installed at IMP. The assembling error of the cavity is less than 0.05 mm. The RF measurements show good electrical properties of the resonant cavity with a measured unloaded quality factor equal to 96.4% of the simulated value. After tuning, we obtained the nominal frequency and field unbalance within 1.0%. Preparation of high-power test of this RFQ is underway. This paper will cover the fabrication details and RF measurements, as well as the progress of high-power test.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL050

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL052

Multi-Physics Analysis of a CW IH-DTL for CIFNEF

DTL, neutron, linac, operation

1129

Q.Y. Tan, M.J. Easton, Q. Fu, P.P. Gan, H.P. Li, Y.R. Lu, Z. Wang
PKU, Beijing, People's Republic of China

The Compact Intense Fast NEutron Facility (CIFNEF) project aims to produce high intense neutrons via the 7Li (d, n) 8Be reaction using a 5 MeV, 10 mA deuteron linac. The main components of the linac are an ion source, a short radio frequency quadrupole (RFQ) and an interdigi-tal H-mode drift tube linac (IH-DTL). The IH-DTL will accelerate the continuous wave (CW) deuteron beam from 1 MeV to 5 MeV with a total cavity length of 1.25 m using Kombinierte Null Grad Struktur (KONUS) design, achieving an accelerating gradient of 3.2 MV/m. The RF power loss for the whole cavity is estimated to be 85 kW. This high power loss is a significant challenge to the cooling design, as it could cause large rises in tempera-ture, thermal deformation and frequency drift. A detailed multi-physics analysis of the CW IH-DTL is presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL052

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL068

The Development of a Nw Fast Harmonic Kicker for the JLEIC Circulator Cooling Ring

kicker, emittance, simulation, electron

1171

G.-T. Park, F. Fors, J. Guo, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
After the first half-scale, 5 harmonic kicker cavity prototyping * for the JLEIC's CCR/ERL electron cooler and the beam dynamic simulation study of the 10-turn CCR **. The optimized circulation cooling turns has been changed to 11 and only 5 odd-harmonic modes from 86.6 MHz to 779.4 MHz plus a DC bias are needed for the harmonic RF kicker system. The new cavity design including the electromagnetic and thermal cooling optimization and its 11 turns beam bunch tracking simulation with the new numerology of RF deflecting voltages will be presented. Further design specifications for its RF harmonic drive and the broadband RF window, coupler and circulator component will be given for handling 5 kW of total RF power.
* Y, Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 122001 (2016).
** Y. Huang, H. Wang et al., Physical Review Accelerators and Beams 19, 084201 (2016).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL068

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL075

Mechanical Design and Error Analysis of a 325 MHz IH-DTL Test Cavity

DTL, alignment, simulation, linac

1186

R. Tang, C.T. Du, X. Guan, K.D. Man, C.-X. Tang, X.W. Wang, Q.Z. Xing, S.X. Zheng
TUB, Beijing, People's Republic of China
J. Li
NUCTECH, Beijing, People's Republic of China

A 325 MHz interdigital H-mode drift tube linac (IH-DTL) test cavity with a modified KONUS beam dynamics is under fabrication at Tsinghua University. The inner diameter of the tank increases from 196.8 to 232.6 mm. The mechanical design is considered carefully because of its small geometry. A three-piece design has been adopted in the mechanical design. The error analysis is carried out to determine the error requirement of machining and alignment. The details of mechanical design and error analysis is presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL075

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBD5

Performance of Nanometre-Level Resolution Cavity Beam Position Monitors at ATF2

feedback, dipole, electron, kicker

1212

T. Bromwich, D.R. Bett, N. Blaskovic Kraljevic, R.M. Bodenstein, P. Burrows, G.B. Christian, C. Perry, R.L. Ramjiawan
JAI, Oxford, United Kingdom
S. Araki, A. Aryshev, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
P. Bambade, S. Wallon
LAL, Orsay, France
S.W. Jang
Korea University Sejong Campus, Sejong, Republic of Korea

A system of three low-Q cavity beam position monitors (BPMs), installed in the interaction point (IP) region of the Accelerator Test Facility (ATF2) at KEK, has been designed and optimised for nanometre-level beam position resolution. The BPMs are used to provide an input to a low-latency, intra-train beam position feedback system deployed in single-pass, multi-bunch mode with the aim of demonstrating intra-train beam stabilisation on electron bunches of charge ~1 nC separated in time by 280 ns. In 2016 the BPM resolution was demonstrated to be below 50 nm using the raw measured vertical positions at the three BPMs. New results will be presented utilising integrated sampling of the raw waveforms, improved BPM alignment and modified cavities to demonstrate a vertical position resolution on the order of 20 nm.

Slides TUZGBD5 [8.557 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBD5

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBE4

Toward High-Power High-Gradient Testing of mm-Wave Standing-Wave Accelerating Structures

experiment, coupling, accelerating-gradient, diagnostics

1224

E.A. Nanni, V.A. Dolgashev, A.A. Haase, J. Neilson, S.G. Tantawi
SLAC, Menlo Park, California, USA
S. Jawla, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA
S. C. Schaub
MIT, Cambridge, Massachusetts, USA
B. Spataro
INFN/LNF, Frascati (Roma), Italy

Funding: This work is supported in part by Department of Energy contract DE-AC02-76SF00515 (SLAC) and DE-SC0015566 (MIT).
We will preliminary testing results for single-cell accelerating structures intended for high-gradient testing at 110 GHz. The purpose of this work is to study the basic physics of ultrahigh vacuum RF breakdown in high-gradient RF accelerators. The accelerating structures consist of pi-mode standing-wave cavities fed with TM01 circular waveguide mode. We fabricated of two structures one in copper and the other in CuAg alloy. Cold RF tests confirm the design RF performance of the structures. The geometry and field shape of these accelerating structures is as close as practical to single-cell standing-wave X-band accelerating structures more than 40 of which were tested at SLAC. This wealth of X-band data will serve as a baseline for these 110 GHz tests. The structures will be powered with a MW gyrotron oscillator that produces microsecond pulses. One megawatt of RF power from the gyrotron may allow us to reach a peak accelerating gradient of 400 MeV/m.

Slides TUZGBE4 [4.644 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE4

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBE5

A Combined Temperature and Magnetic Field Mapping System for SRF Cavities

operation, SRF, niobium, experiment

1228

J.M. Köszegi, K. Alomari, J. Knobloch, O. Kugeler, B. Schmitz
HZB, Berlin, Germany

In the past decade, a significant improvement of SRF cavity performance has been achieved, yet a number of performance limiting mechanisms, such as magnetic flux trapping, still exist. We present a diagnostics tool which combines flux expulsion measurement during the superconducting phase transition with temperature mapping during operation. This system has a time resolution for both temperature and magnetic field mapping of 2 ms for full cavity coverage, so that short-lived events, including cavity quenches, can easily be resolved.

Slides TUZGBE5 [1.358 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE5

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBF3

Betatron Core Slow Extraction at CNAO

betatron, extraction, synchrotron, acceleration

1237

L. Falbo, E. Bressi, S. Foglio, C. Priano
CNAO Foundation, Milan, Italy

CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. Beam is extracted with a momentum selection scheme in which beam enters the third order resonance driven by a betatron core. When irradiating a tumor, it is thought as divided in the longitudinal plane in several slices while each slice is divided in the transverse plane in several spots called voxels. Considering the dose uniformity that can be obtained during extraction, the machine must extract an average intensity related to the voxel that requires less dose. Therefore during a treatment, for some slices, a technique is needed to lower the extracted beam intensity with respect to the nominal one. A way to guarantee the correct average intensity according to the treatment planning requirements, is to introduce a mechanical filter (a degrader) that reduces the intensity of the accelerated particles. However this method used in the first treatments at CNAO showed some disadvantages and it has been replaced by what has been called the "dynamic betatron" method. The paper shows the implementations and the advantages of this method in the CNAO treatments.

Slides TUZGBF3 [2.146 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBF3

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBF5

KlyLac Prototyping for Borehole Logging

klystron, linac, feedback, simulation

1244

A.V. Smirnov, R.B. Agustsson, M.A. Harrison, A.Y. Murokh, A.Yu. Smirnov
RadiaBeam Systems, Santa Monica, California, USA
S. Boucher, T.J. Campese, K.J. Hoyt
RadiaBeam, Los Angeles, California, USA
E.A. Savin
MEPhI, Moscow, Russia
A.A. Zavadtsev
Nano, Moscow, Russia

Funding: Work supported by the U.S. Department of Energy (award No. DE-SC0015721)
Linac-based system for borehole logging exploits KlyLac approach combing klystron and linac sharing the same electron beam, vacuum volume, and RF network enabling self-oscillation due to a positive feedback. The KlyLac prototype design tailors delivering ~1 MeV electrons in a linac section using part of the beam injected from a sheet beam klystron (SBK). The linac part is based on a very robust, high group velocity, cm-wave, and a standing wave accelerating structure of a 'cross-pin' type supplied by a sampler. The SBK part features a permanent magnet solenoid focusing, relatively low voltage, and high aspect ratio beam. The main SBK characteristics (perveance, power, and efficiency) are expected to be similar to that for a magnetron.

Slides TUZGBF5 [3.280 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBF5

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF002

A Cu Photocathode for the Superconducting RF Photoinjector of BERLinPro

cathode, gun, SRF, laser

1247

J. Kühn, M. Bürger, A. Frahm, A. Jankowiak, T. Kamps, G. Klemz, G. Kourkafas, A. Neumann, N. Ohm, M. Schmeißer, M. Schuster, J. Völker
HZB, Berlin, Germany
P. Murcek, J. Teichert
HZDR, Dresden, Germany

The initial commissioning of the Superconducting RF (SRF) photoinjector is done with a Cu photocathode due to its robustness with regard to interactions with the SRF cavity of the injector. Here we present the preparation and characterization of a Cu photocathode plug and the diagnostics to insert the photocathode in the back wall of the SRF cavity. A polycrystalline bulk Cu plug was polished, particle free cleaned and characterized by x-ray photoelectron spectroscopy. During the transfer of the photocathode insert into the gun module the whole process was controlled by several diagnostic tools monitoring the insert position as well as RF, vacuum and cryogenic signals. We discuss the challenges of the photocathode transfer into an SRF cavity and how they can be tackled.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF002

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF003

Dynamic Tuning of the APS-U Booster 5-cell Cavities

booster, resonance, extraction, coupling

1251

G.J. Waldschmidt, M. Abliz, T.G. Berenc, D. Horan, U. Wienands
ANL, Argonne, Illinois, USA

The booster synchrotron for the APS-U is being upgraded to accommodate high-charge bunches, up to 20 nC, for extraction into the MBA lattice. The booster is required to operate at 85% efficiency in order to achieve bunch swap-out into the storage ring. In order to compensate for significant beam-loading effects as well as support a frequency ramp to achieve higher efficiency, a ferrite tuner is being considered to dynamically adjust the cavity frequency. A tuner design will be presented that spans 60 kHz and utilizes a low-loss YIG garnet similar to that used in the Recycler Ring at Fermilab.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF016

Application of SVD Analysis to Deflecting Cavitiy Space Harmonics

simulation, timing, data-analysis, experiment

1283

C. Yao, L. Emery, D. Hui, H. Shang, Y.P. Sun
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Singular value decomposition (SVD) analysis is a powerful tool for identifying different spatial and timing variation patterns in many fields of researches. Recently we applied complex SVD method to space harmonic analysis of a 13-cell defecting cavity that is built and installed in the APS linac injector for beam phase space characterization and emittance exchange experiments. Real and imaginary space harmonics components are extracted from CST simulated data. Fields inside the iris were expressed in analytic forms and produced good agreement. Work is underway to implement the results into elegant simulation model.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF016

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF032

RF Conceptual Design of Normal Conducting Cavity for an eRHIC Rapid Cycling Synchrotron

electron, GUI, coupling, vacuum

1316

B. P. Xiao, M. Blaskiewicz, J.M. Brennan, D. Holmes, K.S. Smith, T. Xin, A. Zaltsman
BNL, Upton, Long Island, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Rapid Cycling Synchrotron (RCS) for the eRHIC Ring-Ring design will provide on energy injection (up to 18 GeV) of high charge, polarized electron bunches to the eRHIC electron storage ring. The RF system comprises a large number of 563MHz fundamental cavities, providing up to 45MV per turn. The cavities will operate in pulsed mode with <20% duty factor, at a repetition rate of 1 Hz. In this paper we report the conceptual RF design of the cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF034

Measuring the Electrical Center and Field Flatness of 704 MHz Deflecting Cavity for LEReC with Wire Stretching System

simulation, diagnostics, pick-up, experiment

1320

T. Xin, J.M. Brennan, J.C.B. Brutus, K. Mernick, K.S. Smith, B. P. Xiao, A. Zaltsman
BNL, Upton, Long Island, New York, USA
W. Johnson
SBU, Stony Brook, New York, USA
H. Wang
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
704 MHz deflecting cavity was designed for the Low Energy RHIC electron Cooling (LEReC) project. The cavity will serve as a major component in diagnostic line. In LEReC project the requirement on the energy spread of the electron beam is extremely high (better than 10^-4) and the diagnostic system has to to be designed accordingly. The 704 MHz transverse deflecting cavity provides the vertical kick to the beam after it passes through the dispersion dipole so that we can measure the energy spread of the core of the bunch. Traditional way of determining the electrical center of the cavity involves the needle pulling and integration of the signal which is prone to the cumulative error. We present the measurement result from a wire stretching system that is much more efficient and accurate compared to the bead/needle pulling method. Both simulation and experimental results are shown in this paper and the potential in further application is discussed at the end.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF042

Design of a High Dose Rate Micro-Focused X-Ray Source

electron, target, emittance, dipole

1346

X. He, S.Q. Liao, J. Long, J. Shi, W. Wang, L. Yang
CAEP/IFP, Mainyang, Sichuan, People's Republic of China

High energy X-ray computer tomography has wide application in industry, especially in quality control of complicated high-tech equipment. In many applications, higher spatial resolution is needed to discover smaller defects. Decreasing the spot size of the X-Ray source is a promising way to get higher spatial resolution. Rhodotron have been used to produce high power CW electron beam in hundreds of kilowatts level. In this paper, we propose to use an improved Rhodotron to generate high brightness electron beam with high average power. Beam dynamics study shows that when producing tens of kilowatts electron beam, the normalized RMS emittance can be lower than 10 μm, and the relative RMS energy spread can be lower than 0.2%. The beam can be focused to a spot size of about 100μm by using a series of quadruple, and converted to X-Ray by using a rotating target within several kilowatts beam power. Improved Rhodotron proposed in this paper is a good candidate of X-ray source for high resolution high energy industrial CT systems.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF048

On-Axis Beam Accumulation Based on a Triple-Frequency RF System for Diffraction-Limited Storage Rings

injection, simulation, accumulation, photon

1359

S.C. Jiang, Z. Duan, G. Xu
IHEP, Beijing, People's Republic of China

Since the multi-bend achromats have been applied to lattice design in the future light source to achieve ultralow emittance, strong sextupoles and concomitant nonlinearities restrict its performance to a certain extent. The empirical understanding is the exclusion of conventional off-axis injection scheme on these light sources. In this paper, we will present a new on-axis beam accumulation scheme, which is based on the triple-frequency RF system. By means of delicate superposition of RF voltage with fundamental and two other harmonic frequencies, a commodious and steady main bucket is able to be formed. The electron bunch from the injector will be kicked into the main bucket on-axis with a reasonable time offset to the circular bunch, and this process may make the minimal disturbance to the experiment users while operating on the top-up mode. The application of this scheme to the High Energy Photon Source (HEPS) will be discussed in the paper, corresponding simulation results are also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF048

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF074

Control of Collective Effects by Active Harmonic Cavity in an MBA-based Light Source with Application to the PETRA Upgrade

impedance, emittance, lattice, synchrotron

1433

Y.-C. Chae, J. Keil
DESY, Hamburg, Germany

Based on the reference lattice for PETRA IV* we investigated collective effects with non-zero current. Out of many possibilities we firstly computed the intrabeam-scattering (IBS) effects on the emittance as well as lifetime as a function of current. The result indicated that PETRA IV would benefit from the reduced peak current when the harmonic cavity lengthens the bunch. The operating point of harmonic cavity was explored by tracking simulations as well as analytic formula. In order to compute the energy spread and bunch length we had used the known impedance function of the APS**. In this way more realistic estimation of IBS effects was expected. However, because of the complex nature of PETRA IV lattice, which includes achromatic cells for undulators, arc cells of octants and straight sectors for damping wigglers, we simplify the longitudinal dynamics by assuming the ring made of 92 multi-bend-achromat (MBA) cells. The optics is approximated as a linear-chromatic transfer map enabling fast tracking and the ring impedance is concatenated into the one location. The detailed collective effects with and without harmonic cavities are presented in the paper.
* J. Keil, "A PETRA IV Lattice Based on Hybrid Seven Bend Achromats", these proceedings.
** Y.-C. Chae and Y. Wang, "Impedance Database II for the Advanced Photon Source Storage Ring", Proc. PAC2007.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF074

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF080

Progress on Multibunch FEL Performance at FLASH

operation, FEL, controls, accelerating-gradient

1452

T. Hellert, Ch. Schmidt
DESY, Hamburg, Germany

At the SASE-FEL user facility FLASH, superconducting TESLA-type cavities are used for acceleration. The high achievable duty cycle allows for operating with long bunch-trains, hence considerably increasing the efficiency of the machine. However, RF induced intra-bunch-train trajectory variations were found to be responsible for significant variations of the SASE intensity within one bunch train. This work presents the latest achievements in improving the multi-bunch FEL performance by reducing the intra-bunch-train variation of RF parameters. Particular attention is given to the static and dynamic detuning of the cavities. It will be shown that the current level of LLRF control is suitable to limit the variation of RF parameters considerably.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF080

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF081

Microphonic Detuning Induced Coupler Kick Variation at LCLS-II

linac, laser, free-electron-laser, beam-loading

1456

T. Hellert
DESY, Hamburg, Germany
W. Ackermann, H. De Gersem
TEMF, TU Darmstadt, Darmstadt, Germany
C. Adolphsen, Z. Li, C.E. Mayes
SLAC, Menlo Park, California, USA

The LCLS-II free-electron laser will be an upgrade of the existing Linac Coherent Light Source (LCLS), including a 4 GeV CW superconducting linac based on the TESLA technology. The high quality factor of the cavity makes it very sensitive to vibrations. The shift of its eigenfrequency (i.e., detuning) will be compensated by the power source in order to assure a constant accelerating voltage. Significant variations of the forward power are expected which result in coupler kick variations induced by the fundamental power coupler. In this work we estimate the magnitude of trajectory jitter caused by these variations. High precision 3D field maps including standing and traveling-wave components for a cavity with the LCLS-II coupler design are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF081

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF086

Status of the ARES RF Gun at SINBAD: From its Characterization and Installation towards Commissioning

gun, linac, status, electron

1474

B. Marchetti, R.W. Aßmann, S. Baark, F. Burkart, U. Dorda, K. Flöttmann, I. Hartl, J. Hauser, J. Herrmann, M. Hüning, K. Knebel, O. Krebs, G. Kube, W. Kuropka, S. Lederer, F. Lemery, F. Ludwig, D. Marx, F. Mayet, M. Pelzer, I. Peperkorn, F. Poblotzki, S. Pumpe, J. Rothenburg, H. Schlarb, M. Titberidze, G. Vashchenko, T. Vinatier, P.A. Walker, L. Winkelmann, K. Wittenburg, S. Yamin, J. Zhu
DESY, Hamburg, Germany

The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) is foreseen to host multiple experiments relating to the production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD-ARES linac will be a conventional S-band linear RF accelerator allowing the production of low charge (0.5 pC - tens pC) ultra-short electron bunches (FWHM length =< 1 fs - few fs) with 100 MeV energy. The installation of the linac will proceed in stages. In this paper we report on the status of the characterization of the ARES RF gun and the installations of the related infrastructure.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF086

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMK006

Sub-fs Electron Bunch Generation Using Emittance Exchange Compressor

emittance, simulation, sextupole, electron

1501

J.M. Seok, M. Chung
UNIST, Ulsan, Republic of Korea
M.E. Conde, J.G. Power
ANL, Argonne, Illinois, USA
G. Ha
PAL, Pohang, Republic of Korea

Sub-fs electron bunch has been pursued in the last decade using several different methods. These methods rely on one of the velocity difference or path length difference to compress a long bunch to sub-fs bunch. Here, we introduce a new method to generate the compression. Emittance Exchange (EEX) beamline makes transverse-to-longitudinal exchange of phase space. In this beamline, a transverse focusing at the upstream introduces a longitudinal compression at the downstream due to the exchange. Since this exchange scheme does not rely on the velocity or the path length differences, it does not require any longitudinal manipulation (e.g. chirp), and it could generate a short bunch with well-controlled nonlinear effects using nonlinear magnets. We present preliminary simulation results of EEX based bunch compression and sub-fs bunch generation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPML053

The BERLinPro SRF Photoinjector System - From First RF Commissioning to First Beam

cathode, SRF, operation, solenoid

1660

A. Neumann, D. Böhlick, M. Bürger, P. Echevarria, A. Frahm, H.-W. Glock, F. Göbel, S. Heling, K. Janke, A. Jankowiak, T. Kamps, S. Klauke, G. Klemz, J. Knobloch, G. Kourkafas, J. Kühn, O. Kugeler, N. Leuschner, N. Ohm, E. Panofski, H. Plötz, S. Rotterdam, M.A.H. Schmeißer, M. Schuster, H. Stein, Y. Tamashevich, J. Ullrich, A. Ushakov, J. Völker
HZB, Berlin, Germany

Funding: The work is funded by the Helmholtz-Association, BMBF, the state of Berlin and HZB.
Helmholtz-Zentrum Berlin (HZB) is currently constructing a high average current superconducting (SC) ERL as a prototype to demonstrate low normalized beam emittance of 1 mm-mrad at 100 mA and short pulses of about 2 ps. To attain the required beam properties, an SRF based photo-injector system was developed and during the past year underwent RF commissioning and was setup within a dedicated diagnostics beamline called Gunlab to analyze beam dynamics of both, a copper cathode and a Cs2KSb cathode as well as their quantum efficiency at UV and green light respectively. The medium power prototype - a first stage towards the final high power 100 mA design - presented here features a 1.4 x λ/2 cell SRF cavity with a normal-conducting, high quantum efficiency CsK2Sb cathode, implementing a modified HZDR-style cathode insert. This injector potentially allows for 6 mA beam current and up to 3.5 MeV kinetic energy, limited by the modified twin TTF-III fundamental power couplers. In this contribution, the first RF commissioning results of the photo-injector module will be presented including dark current analysis as well as measured beam properties with an initially installed Copper cathode.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML053

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPML054

Microbeam Irradiation System with a Dielectric Laser Accelerator for Radiobiology Research

laser, electron, accelerating-gradient, radiation

1664

K. Koyama
KEK, Ibaraki, Japan
Z. Chen
The University of Tokyo, Tokyo, Japan
T. Takahashi
The University of Tokyo, The School of Engineering, Tokyo, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan

Funding: This work was supported by KAKENHI (Grant-in-Aid for Scientific Research)15H03595 and partly supported by NIMS Nanofabrication Platform in Nanotechnology Platform Project sponsored by the MEXT, Japan.
A laser micro-irradiation (LMI) system is widely used in the field of radiobiology because of its acceptably small size. However, damage in a cell nucleus caused by the LMI system does not necessarily simulate a radiation effect. If the laser of the LMI system is replaced with a small-scale 1MeV-class accelerator such as a dielectric laser accelerator (DLA), experiments might be performed under conditions that are more realistic. The desirable configuration of the DLA for a compact micro-beam irradiation system is that laser pulses are transported to a dielectric structure by single-mode optical fibers and the laser energy is accumulated in an accelerator channel. The long and low-intensity laser pulse of 100 MW/cm², 10ps and a resonator with Q=10⁴ are capable of producing the light intensity of 1 TW/cm². The long laser pulse, i.e., low laser induced damage threshold intensity, decreases the acceleration gradient to about 1/3 of the ultra-short pulse irradiation of 100 fs. The length of the accelerator at long-laser pulse might be within the allowable range of several cm. The resonator scheme is useful only for the sub-relativistic regime because of the acceleration gradient.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML054

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPML066

Progress on Beam-Plasma Effect Simulations in Muon Ionization Cooling Lattices

plasma, simulation, emittance, scattering

1696

P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA
J.S. Ellison
IIT, Chicago, Illinois, USA

Funding: Work supported by the Department of Energy.
New computational tools are essential for accurate modeling and simulation of the next generation of muon-based accelerators. One of the crucial physics processes specific to muon accelerators that has not yet been simulated in detail is beam-induced plasma effect in liquid, solid, and gaseous absorbers. We report here on the development of required simulation tools and their applications to studying the properties of plasma and its effects on the beam in muon ionization cooling channels.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML066

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEXGBF1

Testing of the ESS MB-IOT Prototypes

klystron, linac, operation, electron

1759

M. Jensen
ESS, Lund, Sweden
C. Bel, A. Beunas, D. Bussiere, P. Cacheux, V. Hermann, J.C. Racamier, C. Robert
TED, Thonon, France
M. Boyle, H. Schult
L-3, Williamsport, Pennsylvania, USA
G. Cipolla, E. Montesinos, M.S.B. Sanchez Barrueta
CERN, Geneva 23, Switzerland
T. Kimura, P.E. Kolda, P. Krzeminski, L. Kurek, S. Lenci, O.S. Sablic, L. Turek, C. Yates
CPI, Palo Alto, California, USA
M.F. Kirshner
LANL, Los Alamos, New Mexico, USA
R.D. Kowalczyk, A.V. Sy, B.R. Weatherford
SLAC, Menlo Park, California, USA
A. Zubyk
L3 EDD, Williamsport, USA

ESS is considering the use of MB-IOTs for parts of the high-beta linac. Two prototypes have been built by indus-try, namely L3 and CPI/Thales and have passed the factory acceptance test with excellent results. Both tubes will go through further extensive testing at CERN for ESS follow-ing delivery and a final decision on tube technology will be taken in April 2018. This invited talk presents the back-ground for the technical decision of IOTs vs klystrons, associated impact for ESS, and latest plans for industrial production of these IOTs for ESS.

Slides WEXGBF1 [9.836 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBF1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEXGBF3

RF System for FRIB Accelerator

controls, LLRF, rfq, linac

1765

D.G. Morris, J. Brandon, N.K. Bultman, K.D. Davidson, A. Facco, P.E. Gibson, L. Hodges, M.G. Konrad, T.L. Larter, H. Maniar, P. Morrison, P.N. Ostroumov, J.T. Popielarski, G. Pozdeyev, H.T. Ren, T. Russo, K. Schrock, R. Walker, J. Wei, T. Xu, Y. Xu, S. Zhao
FRIB, East Lansing, USA
A. Facco
INFN/LNL, Legnaro (PD), Italy

The RF system of the FRIB driver accelerator includes solid state amplifiers up to 18 kW operating at frequencies from 80.5 MHz to 322 MHz. Much higher power is required for the normal conducting RFQ, ~100 kW, and it is based on vacuum tubes. This invited talk presents the performance of solid state amplifiers and LLRF in off-line testing and on-line testing of the RFQ amplifier.

Slides WEXGBF3 [14.107 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBF3

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEYGBD1

12 GeV CEBAF Initial Operational Experience and Challenges

operation, MMI, cryomodule, experiment

1771

M. F. Spata
JLab, Newport News, Virginia, USA

The 12 GeV Upgrade for the Continuous Electron Beam Accelerator Facility (CEBAF) achieved CD-4B, or Project Completion, on September 27, 2017. The 13-year $338M project doubled the beam energy of the CEBAF accelerator while also adding a fourth experimental hall. The scope of work for the accelerator complex was completed in 2014. Over the subsequent three years the upgrades for the experimental halls were completed, beamlines and spectrometers commissioned and transitions made to production running for the Nuclear Physics program. This paper will present an overview of the operational experience gained during initial accelerator commissioning through the recent achievements of simultaneous 4-Hall operations at full beam power.

Slides WEYGBD1 [15.178 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBD1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEYGBF3

Nb3Sn Multicell Cavity Coating at JLab

niobium, factory, SRF, superconductivity

1798

U. Pudasaini, M.J. Kelley
The College of William and Mary, Williamsburg, Virginia, USA
G. Ciovati, G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA
M.J. Kelley
Virginia Polytechnic Institute and State University, Blacksburg, USA
I.P. Parajuli, MNS. Sayeed
ODU, Norfolk, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics.
Following encouraging results with Nb3Sn-coated R&D cavities, the existing coating system was upgraded to allow for Nb3Sn coating of CEBAF accelerator cavities. The upgrade was designed to allow Nb3Sn coating of original CEBAF 5-cell cavities with the vapor diffusion technique. Several CEBAF cavities were coated in the upgraded system to investigate vapor diffusion coatings on extended structures. Witness samples coated along with the cavities were characterized with material science techniques, while coated cavities were measured at 4 and 2 K. The progress, lessons learned, and the pathforward are discussed.

Slides WEYGBF3 [2.381 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBF3

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF018

Proposed BPM-Based Bunch Crabbing Angle Monitor

simulation, site, electron, diagnostics

1860

P. Thieberger, M.G. Minty, C. Montag
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the US Department of Energy.
A tilted bunch traversing a button beam profile monitor will produce signals on opposite pickup electrodes that will have different degrees of distortion depending on the tilt angle. In particular, the zero-crossing time difference between the two signals will be approximately proportional to the tilt angle. We perform simulations to study this effect as a possible diagnostic tool for measuring the crabbing angles in a future electron-ion collider.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF018

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF027

Low Q Cavity BPM Study for the Beam Position Measurement of Nanosecond Spaced Electron Bunches

FEL, dipole, electron, coupling

1881

L. Yang, X. He, L.W. Zhang
CAEP/IFP, Mainyang, Sichuan, People's Republic of China
S.S. Cao, Y.B. Leng, L.Y. Yu, R.X. Yuan
SINAP, Shanghai, People's Republic of China

Funding: National natural science foundation of China, 11705184
Low Q cavity BPM is a key to distinguish closely spaced electron bunches allowing precise beam handling for XFEL facilities operating in a multi-bunch mode at high repetition rate up to hundreds MHz. The inter-bunch signal pollution issue becomes significant when bunch separation is down to nanosecond and causes the position detection to be increasingly overestimated. Solely relying on extreme low Q to achieve sufficient decay within bunch interval leads to appreciable interference from non-signal modes due to strong overcoupling of antenna design is required. The error imposed on measured position raises a challenge to meet the goal of high resolution. Alternatively, a concept is proposed to remove the dominant part of signal pollution at the moment of sampling by intentionally shifting the phase of the last bunch signal 90degree respect to that of current bunch signal, where signal sampling is normally taken for nanosecond spaced bunches. This quadrature phase shift is defined by properly choosing the operational frequency of dipole mode regarding to the bunch frequency. A low Q cavity BPM prototype to identify technical challenges and verify this concept is under development in the R&D plan for future XFEL with high repetition rate

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF027

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF042

Measurement of Beam yz Crabbing Tilt Due to Wake Fields Using Streak Camera at CESR

wakefield, storage-ring, positron, coupling

1905

S. Wang, D. L. Rubin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This research was supported by NSF PHYS-1068662, PHYS-1416318 and DMR-1332208.
Transverse vertical wake fields can increase the vertical emittance and distort the phase space of a bunch in a storage ring. Recently, we observed charge-dependent vertical beam size growth with a single scraper inserted through the top of the storage ring vacuum chamber. This apparent growth was due in large part to the yz coupling (vertical crabbing) induced by the wake field from the asymmetric scraper configuration. Here, we report a direct measurement of a small beam yz crabbing tilt using a streak camera. The recorded images (projected beam profiles in yz plane) are analyzed with three different methods, which yield consistent beam yz tilts. We found the directly-measured current-dependent beam tilts by the streak camera are consistent with the beam tilts calculated from a wake field model.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF046

RF Electronics for the Measurement of Beam Induced Higher Order Modes (HOM) Implemented in the MicroTCA.4 Form Factor

HOM, dipole, electron, electronics

1916

S. Jabłoński, N. Baboi, U. Mavrič, H. Schlarb
DESY, Hamburg, Germany

Higher order modes (HOM) excited in RF accelerating cavities by a particle beam can be used for electron beam diagnostics. Phase of a monopole HOM provides information about the beam phase relative to the externally induced RF field in a cavity (BPhM) [1]. Furthermore, the amplitude of a dipole mode is proportional to the beam position in the cavity, hence it can be used for beam position monitoring (BPM). In this paper we present a prototype of an instrument implemented in the MicoTCA.4 form factor for the measurement of the HOMs at FLASH and Eu-XFEL. The prototype consists of an analog module, which is used for filtering and conditioning of the selected modes, and a digital module responsible for digitization and signal processing. We present the instruments performance and discuss its influence on the precision of the HOM-based diagnostics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF046

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF050

Simulations of 3D Charge Density Measurements for Commissioning of the PolariX-TDS

simulation, electron, MMI, lattice

1930

D. Marx, R.W. Aßmann, R.T.P. D'Arcy, B. Marchetti
DESY, Hamburg, Germany

The prototype of a novel X-band transverse deflection structure, the Polarizable X-band (PolariX) TDS*, is currently being prepared for installation in the FLASHForward beamline** at DESY in early 2019. This structure will have the novel feature of variable polarization of the deflecting mode, allowing bunches to be streaked at any transverse angle, rather than at just one angle as in a conventional cavity. By combining screen profiles from several streaking angles using tomographic reconstruction techniques, the full 3D charge density of a bunch can be obtained***. It is planned to perform this measurement for the first time during commissioning of the structure. In this paper, simulations of this measurement are presented and the effects of jitter are discussed.
*P Craievich et al. paper THPAL068, this conference
**A Aschikhin et al. Nucl. Instr. Meth. Phys. Res. A., vol.806, pp.175-183, 2018
***D Marx et al. J. Phys.: Conf. Ser., vol.874, p.012077, 2017

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF050

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF052

High QL and High Gradient CW Operation of Tesla SCRF 9-Cell Cavity

feedback, operation, controls, FEL

1937

K.P. Przygoda, V. Ayvazyan, L. Butkowski, M. Hierholzer, R. Rybaniec, H. Schlarb, Ch. Schmidt, J.K. Sekutowicz
DESY, Hamburg, Germany

In the paper we would like to present Tesla SCRF 9-Cell cavity operated at CW regime with extremely high QL at gradients above 23 MV/m. The design hardware and firmware components as well as developed high level software procedures allows automatic procedure of cavity trip from low to high gradient operation. The microphonics as well as a pendoromotive effects are sensed, identify and applied for cavity detuning correction. The RF and piezo feedbacks performance are demonstrated and preliminary results are briefly discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF052

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF063

RF Manipulations for Special LHC-Type Beams in the CERN PS

extraction, emittance, brightness, flattop

1971

H. Damerau, S. Hancock, A. Lasheen, D. Perrelet
CERN, Geneva, Switzerland

Beams with special longitudinal characteristics for the Large Hadron Collider (LHC) have been produced in the Proton Synchrotron (PS) and CERN. The flexibility of its RF systems consisting of in total 25 RF cavities at frequencies from 400 kHz to 200 MHz allows a variety of longitudinal beam manipulations. In particular the main RF system is split into three independent groups tunable from 2.8 MHz to 10 MHz. It is used to merge, split and change the spacing between bunches by applying different voltage and phase programs to the three groups of cavities at different harmonic numbers simultaneously. The batch compression, merging and splitting (BCMS) process has been operationally used for LHC fillings since 2016. To mitigate issues with long bunch trains in the LHC in 2017, short gaps of four bunch positions have been introduced between mini-batches of eight bunches (8b4e). A higher brightness version resulting in four mini-batches per PS extraction has been delivered for luminosity production in the LHC. This paper summarizes the operational experience and indicates possible future RF manipulation schemes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF063

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF068

Frequency Scanning Interferometry as New Solution for on-Line Monitoring Inside a Cryostat for the HL-LHC project

target, vacuum, monitoring, dipole

1986

H. Mainaud Durand, T. Dijoud, J. Gayde, F. Micolon, M. Sosin
CERN, Geneva, Switzerland
M. Duquenne, V. Rude
ESGT-CNAM, Le Mans, France

Funding: Research supported by the HL-LHC project
For the HL-LHC project, the cryostats of the key components will be equipped permanently with an on-line position monitoring system based on Frequency Scanning Interferometry (FSI). Such a system, based on absolute distance measurement, will determine the position of the inner triplet cold masses w.r.t. their cryostat and the position of the crab cavities also inside their cryostat, within an uncertainty of measurement of 0.1 mm, in a harsh environment: cold temperature of 2 K and high radiation level of the order of 1 MGy. The FSI system was validated first successfully on one LHC dipole cryostat and its associated cold mass to undergo qualification tests under different conditions: warm, vacuum and cold (2K). The FSI system also equips the first crab cavities prototype cryostat. The configuration of the FIS system chosen after simulations, the conditions of tests as well as their results and analysis are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF068

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF069

Evaluation of Frequency Scanning Interferometer Performances for Surveying, Alignment and Monitoring of Physics Instrumentation

alignment, laser, target, luminosity

1990

J. Gayde, S.W. Kamugasa
CERN, Geneva, Switzerland

During the last three years, the performance of Frequency Scanning Interferometry, accurate to a few micrometres, has been evaluated at CERN in the frame of the PACMAN project. Improvements have been studied and tested to make it better suited for typical alignment and survey conditions in accelerators and experiments. The results of these developments and tests, coupled with the multi-channel capability of the system, and its compactness which eases its integration in the area to be surveyed, offer a wide scope of possible applications for in-situ large scale metrology for physics equipment and facility elements. Furthermore, the fact that the system electronics can be placed far away from the position to be measured, allows the system to be used in confined and hazardous spaces. This paper briefly describes the system and its improvements. It gives the precision obtained for distance measurements and for the 3D point reconstruction based on FSI observations in the case of CLIC component fiducialisation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF069

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF086

Latest Developments and Updates of the ESS Linac Simulator

DTL, linac, solenoid, space-charge

2051

J.F. Esteban Müller, E. Laface
ESS, Lund, Sweden

A fast and accurate online model is required for optimal commissioning and reliable operation of the high-power proton linac at the European Spallation Source. The Open XAL framework, initially developed at SNS, is used at ESS for the development of high-level physics applications. The online model we use, known as ESS Linac Simulator (JELS), extends the Open XAL model with several features. This paper describes the latest updates carried out to JELS. Two new elements have been implemented: a solenoid field map for the LEBT and a DTL Tank element that automatically calculates each gap phase. All calculations are now done in the laboratory frame, in agreement with Open XAL convention. A thorough benchmark of the model against TraceWin, which is the tool used for the lattice design, is also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF086

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAG002

Tunable Q-Factor Gas-Filled RF Cavity

coupling, hadron, plasma, simulation

2064

M.D. Balcazar, A. Moretti, A.V. Tollestrup, A.C. Watts, K. Yonehara, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
M.A. Cummings, A. Dudas, R.P. Johnson, G.M. Kazakevich, M.L. Neubauer
Muons, Inc, Illinois, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795.
Fermilab is the main institution to produce the most powerful and wide-spectrum neutrino beam. From that respective, a radiation robust beam diagnostic system is a critical element in order to maintain the quality of the neutrino beam. Within this context, a novel radiation-resistive beam profile monitor based on a gas-filled RF cavity has been proposed. The goal of this measurement is to study a tunable Q-factor RF cavity to determine the accuracy of the RF signal as a function of the quality factor. Specifically, the measurement error of the Q-factor in the RF calibration is investigated. Then, the RF system will be improved to minimize signal error.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAG002

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAG003

Hadron Beam Monitor Design with Gas-Filled RF Resonators in Intense Neutrino Source

hadron, scattering, target, radiation

2067

M.D. Balcazar, K. Yonehara
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795.
For the future Long Baseline Neutrino Facility at Fermilab, a new radiation-robust hadron beam profile monitor has been proposed consisting of an interface of gas-filled radiofrequency cavity detectors in the backward region of the LBNF decay pipe. A tailored monitor layout will be used along with the new RF instrumentation. Proposed designs for the detector configuration include a variety of radially symmetric arrangements of RF resonators located at the position of maximum gradient in the beam distribution across the monitor. Until the final detector cavities are available, a prototype tunable Q-factor RF cavity will provide functional emulation for studies of the monitor layout configurations presented here.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAG003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAK001

Intense Neutrino Source Front End Beam Diagnostics System R&D

detector, plasma, target, hadron

2077

K. Yonehara, M.D. Balcazar, A. Moretti, A.V. Tollestrup, A.C. Watts, R.M. Zwaska
Fermilab, Batavia, Illinois, USA
M.A. Cummings, A. Dudas, R.P. Johnson, G.M. Kazakevich, M.L. Neubauer
Muons, Inc, Illinois, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795.
We overview the front end beam diagnostic system R&D to prepare operation of a multi-MW proton beam for intensity frontier Neutrino experiments. One of critical issues is shorter life time of a detector with higher beam intensity due to radiation damage. We show a possible improvement of the existing ion chamber based detector, and a study of a conceptually new radiation-robust detector which is based on a gas-filled RF resonator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK001

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAK006

Bunch Shape Measurements at the GSI CW-Linac Prototype

linac, heavy-ion, bunching, emittance

2091

T. Sieber, W.A. Barth, P. Forck, V. Gettmann, M. Heilmann, H. Reeg, A. Reiter, S. Yaramyshev
GSI, Darmstadt, Germany
F.D. Dziuba, T. Kürzeder, M. Miski-Oglu
HIM, Mainz, Germany
A. Feschenko, S.A. Gavrilov
RAS/INR, Moscow, Russia

The existing GSI accelerator will become the injector for FAIR. To preserve and enhance the current experimental program at UNILAC, a new Linac is under development, which shall run in parallel to the FAIR injector, providing cw-beams of ions at energies from 3.5 - 7.3 MeV/u. For this cw-Linac a superconducting prototype cavity has been developed and was first operated with beam in summer 2017. The resonator is a cross-bar H-structure (CH) of 0.7 m length, with a resonant frequency of 216.8 MHz. It has been installed behind the GSI High Charge State Injector (HLI), which provided 10⁸ MHz bunches of 1.4 MeV/u Ar⁶⁺/9+/11+ ions at a duty cycle of 25 %. Due to the frequency jump and small longitudinal acceptance of the CH, proper matching of the HLI beam to the prototype was required. The bunch properties of the injected beam as well as the effect of different phase- and amplitude-settings of the cavity were measured in detail with a bunch shape monitor (BSM) fabricated at INR, Moscow, while the mean energy was analyzed by time of flight method. In this contribution, the bunch shape measurements are described and the capabilities of the used BSM measurement principle are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAK012

Developing Kalman Filter Based Detuning Control with a Digital SRF CW Cavity Simulator

controls, SRF, FPGA, LLRF

2114

A. Ushakov, P. Echevarria, A. Neumann
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
Continuous wave operated superconducting cavities experiencing small net beam loading and thus operate potentially at narrow bandwidth require precise detuning control to reach the high stability requirements for RF fields within facilities as FEL or ERL based photon sources. Especially microphonics compensation down to sub-hertz detuning regime besides improving stability reduces the risk of rise of Lorentz force detuning driven ponderomotive instabilities. Usually the complex and second order nature of the mechanical to RF detuning transfer functions of cavity and cavity-tuner system require for more advanced control schemes. In this paper we will show the application of a Kalman filter based detuning estimator algorithm first introduced during IPAC2017 [1] to the SRF cavity simulator developed at Helmholtz Zentrum Berlin [2]. Results using the algorithm in observer mode to detuning compensation attempts in closed loop mode are presented.
* A. Ushakov, P. Echevarria, A. Neumann, Proc. of IPAC 2017, Copenhagen, Denmark

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAK013

SRF Cavity Simulator for LLRF Algorithms Debugging

controls, SRF, LLRF, FPGA

2118

P. Echevarria, J. Knobloch, A. Neumann, A. Ushakov
HZB, Berlin, Germany
E. Aldekoa, J. Jugo
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
The availability of niobium superconducting cavities, ei-ther due to a lack of a real cavity or due to the time needed for the experiment set up (vacuum, cryogenics, cabling, etc.), is limited, and thus it can block or delay the develop-ment of new algorithms such as low level RF control. Hardware-in-the-loop simulations, where an actual cavity is replaced by an electronics system, can help to solve this issue. In this paper we present a Cavity Simulator imple-mented in a National Instruments PXI equipped with an FPGA module. This module operates with one intermedi-ate frequency input which is IQ-demodulated and fed to the electrical cavity's model, where the transmitted and re-flected voltages are calculated and IQ-modulated to gener-ate two intermediate frequency outputs. Some more ad-vanced features such as mechanical vibration modes driven by Lorentz-force detuning or external microphonics have also been implemented. This Cavity Simulator is planned to be connected to an mTCA chassis to close the loop with a LLRF control system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK013

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL001

LLRF Control and Master Oscillator System for Damping Ring at SuperKEKB

controls, LLRF, injection, linac

2137

T. Kobayashi, K. Akai, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri
KEK, Ibaraki, Japan
H. Deguchi, K. Hayashi, J. Mizuno
Mitsubishi Electric TOKKI Systems, Amagasaki, Hyogo, Japan
K. Hirosawa
Sokendai, Ibaraki, Japan

For SuperKEKB, new low level RF (LLRF) control systems has ben developed and they worked successfully in the first beam commissioning (Phase-1) of SuperKEKB, which was accomplished in 2016. Damping ring (DR) was newly constructed for positron beam injection, in order to make significantly emittance smaller for SuperKEKB. The beam commissioning of DR will be conducted in JFY2017 for the Phase-2 commissioning. Phase-2 is scheduled in the last quater of JFY2017. DR has an RF station, and two cavities (or three cavities in future) are driven by a klystron. New LLRF control system for DR (DR-LLRF) was also developed and installed. RF frequency of DR operation is common with the main storage rings (MR) of SuperKEKB. The good performance of DR-LLRF was demonstrated in test operation, and RF conditioning of the pair of two cavities was successfully completed in June 2017. This paper reports the detail of the performance results of DR-LLRF controls, and also the other some relevant issues in LLRF controls for DR, including the master oscillator system (synchronization with the injection linac), are introduced.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL001

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL003

Baseband Simulation Model of the Vector RF Voltage Control System for the J-PARC RCS

controls, feedback, simulation, software

2144

F. Tamura, M. Nomura, T. Shimada, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Furusawa, K. Hara, K. Hasegawa, C. Ohmori, Y. Sugiyama, M. Yoshii
KEK, Tokai, Ibaraki, Japan

Vector rf voltage feedback control for the wideband magnetic alloy cavity of the J-PARC RCS is considered to be employed to compensate the heavy beam loading caused by high intensity proton beams. A prototype system of multiharmonic rf vector voltage control has been developed and is under testing. To characterize the system performance, full rf simulations could be performed by software like Simulink, while the software is proprietary and expensive. Also, it requires much computing power and time. We performed the simplified baseband simulations of the system in z-domain by using free software, Scilab and Python control library. It seems to be beneficial for searching the parameters that the baseband simulation can be performed quickly. In this presentation, we present the setup and results of the simulations. The simulations well reproduce the open and closed loop responses of the prototype system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL008

Low-level RF System for The Chinese ADS Front-end Demo Linac

controls, LLRF, linac, interface

2159

J.Y. Ma, Z. Gao, G. Huang, L.P. Sun
IMP/CAS, Lanzhou, People's Republic of China

The Chinese ADS Front-end Demo Linac (FDL) is constructed to demonstrate the technology of superconducting linac with high proton beam loading of CW 10mA. The low-level RF (LLRF) control system for the ADS FDL is developed by IMP, and the cooperation with TRIUMF. In the normal conducting (NC) section, the normal RF feedback control loop is used. In order to stable the superconducting (SC) cavity with loaded high RF power, the self excited loop with phase locked mode was used on the SC linac. This paper introduces the LLRF control system for buncher, SC linac, and the structures of hardware and the functions of software of these LLRF systems. The operating status of the LLRF systems is also reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL008

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL012

Measurements with the ELI-NP Cavity Beam Position Monitor Read-out Electronics at FLASH

electron, instrumentation, electronics, FEL

2169

G. Franzini, D. Pellegrini, M. Serio, A. Stella, A. Variola
INFN/LNF, Frascati (Roma), Italy
B.B. Baricevic, M. Cargnelutti
I-Tech, Solkan, Slovenia
D. Lipka
DESY, Hamburg, Germany
M. Marongiu
INFN-Roma, Roma, Italy
A. Mostacci
Sapienza University of Rome, Rome, Italy

The Extreme Light Infrastructure - Nuclear Physics Gamma Beam Source (ELI-NP GBS) will be installed and commissioned starting within the next year in Magurele, Romania. It will generate gamma beam through Compton back-scattering of a recirculated laser and a multi-bunch electron beam, produced by a 720 MeV LINAC. In order to obtain bunch by bunch position measurements, four cavity beam position monitors (cBPM) near the two interaction points are foreseen. Extensive tests on the cBPM read-out electronics, recently developed by Instrumentation Technologies and acquired for ELI-NP GBS, were performed in laboratory at INFN-LNF and at FLASH in DESY, during the user operation. In the latter case, three cBPMs installed along the LINAC, with similar features as the ones of ELI-NP GBS, were used as measuring devices and signal sources for the read-out electronics under test. We present here the measurements collected and the related analysis, with a particular focus on the beam position measurement resolution.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL014

Non-Distructive 2-D Beam Profile Monitor Using Gas Sheet in J-PARC LINAC

linac, injection, electron, vacuum

2177

J. Kamiya, Y. Hikichi, M. Kinsho, A. Miura, N. Ogiwara
JAEA/J-PARC, Tokai-mura, Japan

We have been developed a beam profile monitor using interaction between the beam and the gas molecules distributed in sheet shape*. Generated luminescence or ions by passing the beam through the gas sheet has the information of cross-section shape of the beam. The gas sheet beam monitor will become a useful tool to measure the profile of high power beams because it has no breakable element such as wires and a 2-D beam profile at a certain position of beam line can be immediately obtained by just injecting the gas. Previously, the development of the gas sheet generator and successful demonstration of the beam profile measurement were reported. This time, we applied a gas sheet monitor to J-PARC LINAC, where the negative hydrogen atoms (H⁻) are accelerated to the energy of 400 MeV in the normal operation. Most challenging factor was the development of the gas sheet monitor system, which generates the enough dense gas sheet to detect the clear image of the beam profile without harmful effect on the ultra-high vacuum in the beam line. We will report the gas sheet beam monitor system for J-PARC LINAC and the results of the first measurement of the beam profile.
* N. Ogiwara, et al., Proceedings of IPAC2016, p.2102.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL014

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL016

Tensile Fracture Test of Metallic Wire of Beam Profile Monitors

linac, electron, beam-loading, controls

2183

A. Miura, Y. Kawane, K. Moriya
JAEA/J-PARC, Tokai-mura, Japan
S. Fukuoka
Nihon Koshuha Co. Ltd, Yokohama, Japan
K. Futatsukawa, T. Miyao
KEK, Ibaraki, Japan

In order to mitigate the beam loss during a beam transportation in a high-brilliant accelerator facilities, wire-based profile monitors are used to measure by both transverse and longitudinal beam profiles using wire-scanner monitors (WSMs) and bunch-shape monitors (BSMs) for the tuning of quadrupole magnets and bunching cavities. Signals are come from the direct interaction between a metallic wire and beam. We have used the tungsten wire as a high melting-point material by estimation of heat loading during the impact of beam particles. In addition, a spring is applied for the relaxing a sag under wire's own weight. A tensile fracture test is conducted by supplying an electrical current as a simulated beam-heat loading. As the results, we obtained the relation between the thermal limit to break down and tension loading of tungsten wire.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL016

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL017

Adaptive Feedforward Control Design Based on Simulink for the J-PARC LINAC LLRF System

controls, LLRF, linac, simulation

2187

S. Li
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Z. Fang, Y. Fukui, K. Futatsukawa, F. Qiu
KEK, Ibaraki, Japan
S. Mizobata, Y. Sato, S. Shinozaki
JAEA/J-PARC, Tokai-mura, Japan

In j-parc linac, for dealing with high beam loading effect, an adaptive feedforward control method which based on iterative learning control was put forward. At the same time, in order to verify its effectiveness before it is officially put into use, an llrf system simulation model was built in simulink, matlab. In this paper, the architecture of llrf system simulation model will be introduced. The result of iterative learning control (ILC) is summarized.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL017

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL021

Study of a Tuner for a High-Accuracy Bunch Shape Monitor

linac, insertion, resonance, electron

2200

K. Moriya, Y. Kawane, A. Miura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
K. Futatsukawa, T. Miyao
KEK, Ibaraki, Japan

In the J-PARC Linac, development and higher precision of Bunch Shape Monitor (BSM) have been progressed for measuring the longitudinal beam distribution. To transform a longitudinal beam-profile into transverse one with an rf field, we need the field having an acceleration synchronizing frequency. An rf deflector of BSM consists of a half λ cylindrical cavity and two electrodes for deflection. In general, the resonance frequency can be tuned by adjusting the electrode length. We designed the new tuner with CST Studio. We can control the resonance frequency by Adjusting not only the electrode length but the cavity volume. We found the optimum lengths of electrode and volume for tuning. We introduce development of the new rf tuner for BSM in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL021

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL024

High Precision Beam Parameter Stabilization for P2 at MESA

experiment, electron, controls, resonance

2209

R.F.K. Kempf, J. Diefenbach
IKP, Mainz, Germany
K. Aulenbacher
HIM, Mainz, Germany

Funding: Cluster of Excellence PRISMA (EXC 1098/2014) German Research Foundation DFG (GRK 2128)
The experiment P2 will measure the weak mixing angle with an all-time high precision via electron-proton scattering. The measured physics asymmetry and its uncertainty has to be corrected by the apparatus' asymmetry, which is generated by helicity correlated fluctuations of the beam parameters position, angle, intensity and energy. This Poster will describe how the high precision of 0.1 ppb of the parity violating asymmetry can be provided by the high precision measurements of the parameters position, angle and intensity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL024

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL025

Development of a Low-Latency, High-Precision, Beam-Based Feedback System Based on Cavity BPMs at the KEK ATF2

feedback, dipole, kicker, extraction

2212

R.L. Ramjiawan, D.R. Bett, N. Blaskovic Kraljevic, R.M. Bodenstein, T. Bromwich, P. Burrows, G.B. Christian, C. Perry
JAI, Oxford, United Kingdom

A low-latency, intra-train feedback system employing cavity beam position monitors (BPMs) has been developed and tested at the Accelerator Test Facility (ATF2) at KEK. The feedback system can be operated with either position information from a single BPM to provide local beam stabilisation, or by using position information from two BPMs to stabilise the beam at an intermediate location. The correction is implemented using a stripline kicker and a custom power amplifier, with the feedback calculations being performed on a digital board built around a Field Programmable Gate Array (FPGA). The addition of indium sealing to the BPMs to increase the cavities' Q-values has led to improvements to the BPM system resolution, with current measurements of the resolution of order 20 nm. The feedback performance was tested with beam trains of two bunches, separated by 280 ns and with a charge of ~1 nC. For single- (two-)BPM feedback, stabilisation of the beam has been demonstrated to below 50 nm (41 nm). Ongoing work to improve the feedback performance further will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL025

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL029

FLUTE Diagnostics Integration

controls, diagnostics, interface, linac

2227

M. Yan, A. Bernhard, E. Bründermann, S. Funkner, A. Malygin, S. Marsching, W. Mexner, A. Mochihashi, A.-S. Müller, M.J. Nasse, G. Niehues, R. Ruprecht, T. Schmelzer, M. Schuh, N.J. Smale, P. Wesolowski, S. Wüstling
KIT, Karlsruhe, Germany
I. Križnar
Cosylab, Ljubljana, Slovenia

FLUTE (Ferninfrarot Linac- Und Test-Experiment) will be a new compact versatile linear accelerator at KIT. Its primary goal is to serve as a platform for a variety of accelerator studies as well as to generate strong ultra-short THz pulses for photon science. The machine consists of an RF gun, a traveling wave linac and a D-shaped bunch compressor chicane with corresponding diagnostics sections. In this contribution, we report on the latest developments of the diagnostics components. An overview of the readout and control system integration will be given.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL029

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL031

RF Interlock Implementation Using Digital LLRF System for 100 MeV Proton Linac at KOMAC

pick-up, LLRF, controls, proton

2233

H.S. Jeong, Y.-S. Cho, H.S. Kim, J.H. Kim, S.G. Kim, H.-J. Kwon, Y.G. Song
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work has been supported through KOMAC (Korea Multi-purpose Accelerator Complex) operation fund of KAERI by MSIT (Ministry of Science and ICT)
KOMAC (Korea Multi-purpose Accelerator Complex) already has operated 100 MeV proton linear accelerator with high availability since 2013. This accelerator is composed of Ion source, LEBT, RFQ and DTL systems to transport proton particles to the target. Total 9 klystrons with 1.6 MWpeak are used to provide controlled RF power to the accelerator cavities with 350 MHz of operating frequency. These klystrons are driven by LLRF systems that the LLRF systems should control the RF and protect the amplifiers and cavities from the abnormal RF. In this article, the RF interlock using cavity pickup signal introduced. When the cavity pickup amplitude breaks away from the adjustable upper or lower limit window, the digital LLRF system interrupts the LLRF output. These implementations were conducted by upgrading the FPGA (Field Programmable Gate Array) logics of the existing digital LLRF system.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL031

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL039

LCLS-II Gun/Buncher LLRF System Design

gun, LLRF, SRF, controls

2258

G. Huang, K.S. Campbell, L.R. Doolittle, J.A. Jones, Q. Qiang, C. Serrano
LBNL, Berkeley, California, USA
S. Babel, A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, J.H. De Long, J.A. Diaz Cruz, B. Hong, A. McCollough, A. Ratti, C.H. Rivetta, D. Rogind, F. Zhou
SLAC, Menlo Park, California, USA
R. Bachimanchi, C. Hovater, D.J. Seidman
JLab, Newport News, Virginia, USA
B.E. Chase, E. Cullerton, J. Einstein-Curtis, D.W. Klepec
Fermilab, Batavia, Illinois, USA
J.A. Diaz Cruz
CSU, Fort Collins, Colorado, USA

Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract n. DE-AC02-05CH11231.
For a free electron laser, the stability of injector is critical to the final electron beam parameters, e.g., beam energy, beam arrival time, and eventually it determines the photon quality. The LCLS-II project's injector contains a VHF copper cavity as the gun and a two-cell L-band copper cavity as its buncher. The cavity designs are inherited from the APEX design, but requires more field stability than demonstrated in APEX operation. The gun LLRF system design uses a connectorized RF front end and low noise digitizer, together with the same general purpose FPGA carrier board used in the LCLS-II SRF LLRF system. The buncher LLRF system directly adopts the SRF LLRF chassis design, but programs the controller to run the normal conducting cavities. In this paper, we describe the gun/buncher LLRF system design, including the hardware design, the firmware design and bench test.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL041

FPGA Based Optical Phase Control for Coherent Laser Pulse Stacking

controls, experiment, FPGA, laser

2265

Y. Yang, L.R. Doolittle, Q. Du, G. Huang, W. Leemans, R.B. Wilcox, T. Zhou
LBNL, Berkeley, California, USA
A. Galvanauskas
University of Michigan, Ann Arbor, Michigan, USA

Coherent temporal pulse stacking combines the energy from a train of pulses into one pulse through a series of optical cavities. To stabilize the output energy, the cavity roundtrip phases must be precisely locked to particular values. Leveraging the LLRF expertise we have for conventional accelerators, a FPGA-based control system has been developed for optical cavity phase control. A phase measurement method, ''Modulated Impulse Response'', has been developed and implemented on FPGA. An experiment demonstrated that it can measure and lock the optical phases of four stacking cavities, leading to combination of 25 pulses into one pulse with 1.5 % RMS stability over 30 hours.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL041

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL046

A New Digital Feedback and Feedforward Controller for Cavity Field Control of the LANSCE Accelerator

controls, feedback, LLRF, FPGA

2277

S. Kwon, L.J. Castellano, D.J. Knapp, J.T.M. Lyles, M.S. Prokop, A. Scheinker, P.A. Torrez
LANL, Los Alamos, New Mexico, USA

Funding: Work Supported by DOE
A new digital low-level RF system was designed and has been deployed on the drift-tube-linac section of the Los Alamos Neutron Science Center(LANSCE) proton accelerator. This new system is part of a modernization of the existing analog cavity-field controls that were originally developed and put into service forty-five years ago. For stabilization of the cavity field amplitude and phase during beam loading, a proportional-integral feedback controller, a static beam feedforward controller, and an iterative learning controller working in parallel have been implemented. In this paper, the controller architecture is described, and the performances of the three controllers when beam is being actively accelerated is presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL046

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL053

Dynamic Signal Analysis Based on FPGA for NSRRC DLLRF

FPGA, LLRF, controls, feedback

2295

F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.T. Li, M.-C. Lin, Z.K. Liu, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
NSRRC, Hsinchu, Taiwan

As DLLRF control system designs for SRF cavities have greatly matured and the FPGA technology has im-proved as well, it is possible now to think about incorporating dynamic signal analysis (DSA). Implementation of a DSA in the FPGA is desired to study the frequency response of the open/closed loop gain in a SRF system. Open loop gain is useful to observe the stability of a SRF system while closed loop gain can be applied to investi-gate the operational bandwidth of the system feedback and also to configure the performance of a PID controller. The DSA function was confirmed by analyzing the frequency response of a digital filter and the results of the analysis will be compared with MATLAB simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL053

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL054

Digital Low Level Radio Frequency System for the Booster Ring of the Taiwan Photon Source

LLRF, controls, operation, booster

2298

Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.T. Li, M.-C. Lin, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
NSRRC, Hsinchu, Taiwan

The purpose of a Low-Level Radio Frequency (LLRF) system is to control the accelerating cavity field amplitude and phase. For the Taiwan Photon Source (TPS) at NSRRC, the currently operating LLRF systems are based on analog technology. To have better RF field stability, precise con-trol and high noise reduction, a digital LLRF control sys-tems based on Field Programmable Gate Arrays (FPGA) was developed. We replaced the analog LLRF system with the digital version for the TPS booster ring at the beginning of 2018, and we will replace those in the storage rings in the future. Test results and operational performance of the TPS booster DLLRF system are reported here.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL054

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL057

Methods to Detect Error Sources and Their Application at the TPS

photon, kicker, storage-ring, injection

2305

C.H. Huang, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, K.H. Hu, C.Y. Wu
NSRRC, Hsinchu, Taiwan

For a low-emittance photon light source, beam stability is a very important property to attain a high-quality photon beam. While it is hard to avoid beam perturbations in a storage ring, it is more important to quickly find the source locations and to remove or eliminate the sources as soon as possible. In this report, we develop a method to identify the locations of multiple sources. For a source with a particular frequency, the relative phase between sources can also be obtained. This method has been a useful tool during TPS operation and its methodology and practical applications are described in this report.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL057

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL069

Reentrant Cavity Resonator for Low Intensities Proton Beam Measurements

simulation, pick-up, resonance, scattering

2341

S. Srinivasan, P.-A. Duperrex
PSI, Villigen PSI, Switzerland

A non-interceptive beam current monitor has been developed to investigate the measurement possibilities of low-intensity beams down to 1 nA for proton therapy machines without the drawback of interceptive monitors. This works on the principle of a reentrant cavity resonator such that its fundamental mode resonance frequency of 145.7 MHz matches the second harmonic of the pulse repetition rate of the cyclotron beam i.e. 72.85 MHz. The Driven Modal analysis from the simulation tool ANSYS HFSS was used for parametric model development and to optimize design parameters such as e.g. the position of the inductively coupled pick-ups. A ceramic plate has been inserted in the resonator gap to relax the precision required during manufacturing. A test bench has been designed and constructed for the characterization tests of the prototype. Comparison of the simulated and the experimental scattering parameter from the test bench shows a good agreement.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL069

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF002

Operational Experience with IOTs at Alba Synchrotron

cathode, electron, operation, controls

2372

J.R. Ocampo, B. Bravo, R. Fos, F. Pérez, A. Salom, P. Solans
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
S. Bethuys, A. Beunas, M. Grezaud, P. Reynaud
TED, Velizy-Villacoublay, France
M. Boyle, J. Cipolla, W.F. Coyle, H. Schult
L-3, Williamsport, Pennsylvania, USA

ALBA is a 3 GeV Synchrotron light source in operation since 2012. The RF systems are based in Inductive Output Tube (IOT) transmitters. A total of 13 80 kW IOT amplifiers are used to power the Storage Ring and Booster cavities at 500 MHz. The transmitters were initially configured to operate the TH-793-1 and TH-794 IOT from THALES Electron devices. On 2015, the amplifiers have been adapted to operate also the TH-795 from THALES and the L4444-C from L3 Communications. In this paper, a brief overview of the differences between these IOT models will be presented, as well as operation results for each type of IOT from the point of view of performance, reliability and durability.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF002

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF004

The Saclay Test Stand for Conditioning the ESS RFQ Power Couplers at High RF Power

rfq, vacuum, linac, interface

2375

N. Misiara, A.C. Chauveau, D. Chirpaz-Cerbat, P. Daniel-Thomas, M. Lacroix, L. Maurice
CEA/IRFU, Gif-sur-Yvette, France
M. Desmons, A. Dubois, A. Gaget, L. Napoly, M. Oublaid, G. Perreu, O. Piquet, B. Pottin, Y. Sauce
CEA/DRF/IRFU, Gif-sur-Yvette, France

The RF power coupler system for the RFQ of the ESS LINAC will feed 1.6 MW peak power through two coaxial loop couplers for a 352.21 MHz operation at the expected duty cycle. A specific test stand has been designed to condition the power couplers, and test the different auxiliary components in the nominal conditions of the RFQ. The power couplers were successfully assembled, installed and instrumented on the test cavity. This paper presents the general layout of the test stand, the installation and preparation of the power couplers for their conditioning at high RF power up to the ESS nominal conditions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF004

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF005

Design and Testing of a 12 kW, 352 MHz Solid State rf System at the Advanced Photon Source

controls, operation, GUI, simulation

2378

D. Horan, D.J. Bromberek, A. Goel, T.J. Madden, A. Nassiri, G.J. Waldschmidt
ANL, Argonne, Illinois, USA

A 12 kW, 352 MHz rf power amplifier system was designed and constructed at the Advanced Photon Source as a research and development test bed for eventual development of a 200 kW cw rf system capable of supporting accelerator beam operation. The system utilizes six 2 kW laterally diffused metal oxide field effect transistor (MOSFET) rf amplifiers, an output cavity combiner terminated with a WR2300 waveguide output flange, and a monitoring system based on programmable logic controller technology. The combining cavity has a total capacity of 10⁸ two-kilowatt inputs to support eventual operation up to 216kW maximum output power. Design details and operational performance of the 12 kW system will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF005

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF009

Influence of Argon-Ion Irradiation on Field Emission from Polycrystalline Cu and Large-Grain NB Surfaces

radiation, niobium, experiment, vacuum

2384

S. Soykarci
University of Wuppertal, Wuppertal, Germany
D. Lützenkirchen-Hecht, V. Porshyn, P. Serbun
Bergische Universität Wuppertal, Wuppertal, Germany

Funding: This work is funded by the BMBF project 05H15PXRB1.
In the present work, systematic investigations of the enhanced field emission (EFE) from polycrystalline copper and large grain niobium surfaces before and after argon-ion irradiation with an energy of 5 keV were performed with a variation of the irradiation time. Results show that the suppression of the EFE might be achievable.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF009

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF010

Laser Treatment of Niobium Surface for SRF Aplications

laser, niobium, experiment, electron

2387

V. Porshyn, D. Lützenkirchen-Hecht, P. Serbun
Bergische Universität Wuppertal, Wuppertal, Germany
H. Bürger, S. Soykarci
University of Wuppertal, Wuppertal, Germany

Funding: The research was funded by the German Federal Ministry of Education and Research (BMBF) under project number 05H15PXRB1.
We report on a laser surface treatment of high purity niobium (110) single crystals. Typical surface defects like scratches, pits, sharp rims and holes were eliminated by a focused pulsed ns-laser beam. A laser fluence of about 0.68 J/cm² and 40 - 80 pulses per spot were required to induce well detectable surface modifications. The remelted surface was sufficiently smooth, but exhibited also a number of wave structures. Thus, the surface roughness slightly increased with increasing number of pulses. Finally, boiling traces and μm-deep ablation were observed and studied as well. Local field electron emission measurements showed no emission up to 700 MV/m from a moderate remelted area below the boiling point.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF011

Design and Status of Sirius Light Source RF Systems

storage-ring, booster, LLRF, lattice

2391

R.H.A. Farias, A.P.B. Lima, L. Liu, F.S. Oliveira
LNLS, Campinas, Brazil

Sirius is the new synchrotron light source currently under construction at the site of the Brazilian Synchro-tron Light Laboratory (LNLS) in Campinas, Brazil. The facility comprises a 3 GeV electron storage ring, a full energy booster and a 150 MeV linac. This work provides a brief description of the RF system of the booster and storage ring, presenting their main characteristics and specification goals.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF012

Power Requirement and Preliminary Coupler Design for the eRHIC Crab Cavity System

operation, proton, electron, SRF

2394

S. Verdú-Andrés, I. Ben-Zvi, D. Holmes, Q. Wu
BNL, Upton, Long Island, New York, USA
I. Ben-Zvi
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates LLC under contract no. DE-SC0012704 with the U.S. Department of Energy.
Crab cavities are deflecting cavities operated in such a way that the bunch center is in synchronism with the zero-crossing kick voltage. In that case, beam loading is zero for an on-axis beam. The crab cavity system of the future electron-ion collider eRHIC will manipulate 275 GeV proton beams. At high energies, the beam offset can be as large as 2 mm (including mechanical and electrical offset tolerances). The beam loading resulting from such offset can greatly incur in large power requirements to the RF amplifier. The choice of external Q for the Fundamental Power Coupler (FPC) is critical to limit the power requirement to practical values. The loaded Q of the eRHIC crab cavities is mainly governed by the external Q of the FPC, so the external Q will also define the cavity bandwidth and thus the tuning requirements to counteract frequency transients from external perturbations. This paper discusses the choice of external Q for the FPC of the eRHIC crab cavities and introduces the design of a preliminary FPC antenna concept that would provide the appropriate external Q.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF022

Coulped Multiphysics Simulation for the Water Cooling Layout of a Rhodotron Cavity

simulation, operation, vacuum, electron

2416

L. Yang, X. He, H. Li, S.Q. Liao
CAEP/IFP, Mainyang, Sichuan, People's Republic of China

A Rhodotron-based electron accelerator served as micro-focused X-ray source is under development at IFP, CAEP. The RF-cavity, running in long pulse/ CW mode, will deliver 9 MeV energy to electron beams after multiple accelerations within the same field at a frequency of 10⁷.5MHz. A substantial amount of average power loss with tens of kW will be dissipated on the RF surface of the cavity to maintain the operational field level. Efficient water cooling is critical to prevent large scale temperature rise for stable operation sake. Reasonable prediction of temperature rise becomes essential to assess a certain cooling layout in the design phase. The frequency drift and thermal stress on account of temperature variation and gradient on cavity wall respectively, could be computed accordingly. This paper presents a comprehensive coupled simulation involving electromagnetic, thermal and structural for the RF-cavity of Rhodotron.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF030

Optimization of Klystron Efficiency with MOGA

klystron, electron, simulation, bunching

2419

C. Meng, X. He, S. Pei, S.C. Wang, O. Xiao, Z.S. Zhou
IHEP, Beijing, People's Republic of China

As the very important element of accelerator the klystron provide power to cavities for accelerating. Considering the accelerator cost of construction and running, the improvement of klystron efficiency is one developing hotspot of klystron research. In this paper the optimization method of klystron efficiency with MOGA based on 1D simulation program is proposed and the influences on klystron efficiency will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF033

RF Study And Cold Test of an S-band Spherical Cavity Pulse Compressor

coupling, simulation, vacuum, klystron

2429

J. Lei, X. He, M. Hou, X.P. Li, G. Pei, H. Wang, J.B. Zhao
IHEP, Beijing, People's Republic of China
S. Shu
Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China

An S-band (2856 MHz) spherical cavity pulse compressor has been designed, fabricated and tested in the Institute of High Energy Physics (IHEP), Chinese Academy of Sciences (CAS). The pulse compressor consists of a special 3 dB coupler and only one spherical energy storage cavity, two TE114 modes are chosen to oscillate in which for fairly high unload Q factor. The prototype was made of aluminum for studying the performance of the pulse compressor and checking the validity of the simulations. The cold test results of the aluminum cavity are also presented. The copper coating on the whole internal surface of the aluminum spherical cavity is in progress and the test results will also be presented in the future.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF033

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF034

Development of Superconducting RF Double Spoke Cavity at IHEP

coupling, target, electron, proton

2432

Z.Q. Zhou, H.F.S. Feisi, W.M. Pan
IHEP, Beijing, People's Republic of China

Funding: State Key Development Program for Basic Research of China (Grant No.2014CB845500)
The China Initiative Accelerator Driven System (CiADS) has been approved to transmute long-lived radi-oisotopes in used nuclear fuel into shorter-lived fission products. IHEP is developing a 325MHz double spoke cavity at β0 of 0.5 for the CiADS linac. The cavity shape was optimized to minimize Ep/Ea while keeping Bp/Ep reasonably low, while the multipacting was analyzed. Meanwhile, mechanical design was applied to check stress, Lorentz force detuning and microphonic effects, and to minimize pressure sensitivity. A new RF coupling scheme was proposed to avoid electrons hitting directly on ceramic window. The detailed design for the cavity is addressed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF035

Investigating the Effect of Inhomogeneous Resistivity on Bulk RRR and Heat Conductivity Using a Lattice Green's Functions Method

network, niobium, lattice, HOM

2436

N.C. Shipman, A. Macpherson
CERN, Geneva, Switzerland
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
J.A. Mitchell
Lancaster University, Lancaster, United Kingdom

A method was developed to calculate the bulk RRR (residual resistivity ratio) which would be measured on a superconducting cavity or sample with an inhomogeneous resistivity and arbitrary geometry. The method involves modelling the object as a network of resistors and employs lattice Green's functions. A further adaptation of the method which allows the heat transport characteristics of such an object to be predicted is also described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF035

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF036

RF Test Result of a BNL N-Doped 500 MHz B-Cell Cavity at Cornell

SRF, vacuum, superconducting-cavity, niobium

2440

F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, M. Liepe, J.T. Maniscalco, J. Sears
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
F. Gao, J. Rose
BNL, Upton, Long Island, New York, USA

Cornell's SRF group has collaborated with Brookhaven National Laboratory (BNL) on one 500 MHz CESR type SRF "B-cell" cavity (BNL B-cell) for the National Synchrotron Light Source II. Cornell has been responsible for RF surface preparation, vertical testing, and short cavity string assembly. As a state-of-the-art surface preparation protocol, Cornell selected Nitrogen doping for the BNL B-cell. N-doping has been well demonstrated and established to push the cavity quality factor (Q0) higher in 1.3GHz SRF cavities at many laboratories. Cornell calculated that N-doping could also be beneficial on a 500MHz SRF cavity, with a potential to increase its Q0 by a factor of two compared with the traditional chemical polishing based surface preparation protocol. Here we report on the detailed surface preparation and vertical test result of the BNL B-cell.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF036

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF037

HF Free Bipolar Electro-Polishing Studies on Niobium SRF Cavities at Cornell With Faraday Technology

SRF, niobium, MMI, radio-frequency

2443

F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, P.N. Koufalis, M. Liepe, J. Sears
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T.D. Hall, M.E. Inman, R. Radhakrishnan, S.T. Snyder, E.J. Taylor
Faraday Technology, Inc., Clayton, Ohio, USA

Cornell's SRF group and Faraday Technology have been collaborating on two phase-II SBIR projects. One of them is the development and commissioning of a 9-cell scale HF free Bipolar Electro-Polishing (BEP) system. Faraday Technology has upgraded their 1.3 GHz single-cell BEP system for hosting 9-cell cavities. Initial commissioning of the new system was done with a three single-cell cavity string, and high a gradient of 40MV/m was demonstrated during the RF tests at Cornell. After this success with the test string, the 9-cell cavity was processed with the new system at Faraday and RF test was performed at Cornell. Here we report detailed results from these 9-cell scale HF free BEP studies.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF037

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF038

Microphonics Suppression in the CBETA Linac Cryomodules

linac, cryomodule, SRF, controls

2447

N. Banerjee, J. Dobbins, F. Furuta, G.H. Hoffstaetter, R.P.K. Kaplan, M. Liepe, P. Quigley, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was performed through the support of New York State Energy Research and Development Agency. The linac cryomodules were constructed with funding from the National Science Foundation.
The Cornell-BNL ERL Test Accelerator (CBETA) is a new multi-turn energy recovery linac currently under construction at Cornell University. It uses two superconducting linacs, both of which are susceptible to microphonics detuning. The high-current injector accelerates electrons to 6 MeV and the main linac accelerates and decelerates electrons by 36 MeV. In this paper, we discuss various measures taken to reduce vibrations caused by instabilities and flow transients in the cryogenic system of the main linac cryomodule. We further describe the use of a Least Mean Square algorithm in establishing a stable Active Microphonics Compensation system for operation of the main linac cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF038

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF039

Experimental Results on the Field and Frequency Dependence of the Surface Resistance of Niobium Cavities

niobium, vacuum, experiment, electron

2451

P.N. Koufalis, M. Liepe, J.T. Maniscalco, T.E. Oseroff
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

We investigate the field and frequency dependence of the surface resistance of single-cell niobium cavities as a function of surface treatment at 1.3, 2.6, and 3.9 GHz. The surface resistance is broken down into two parts: the temperature-independent residual resistance and the temperature-dependent BCS resistance. While the low-field BCS resistance is known to vary quadratically with frequency, the exact dependence of the BCS and residual resistances on field at higher frequencies are important topics for further investigation. We offer results on a systematic experimental study of the residual and BCS resistance as a function of frequency and field for clean niobium and high-temperature nitrogen-doped niobium.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF041

Insights into the Role of C, N, and O Introduced by Low Temperature Baking on Niobium Cavity Performance

niobium, experiment, ECR, superconductivity

2455

P.N. Koufalis, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Previous experiments have shown that introducing nitrogen gas during low temperature bakes (120-160 C) of niobium cavities introduces C, N, and O impurities to the first 10-100 nm of the surface. This new treatment results in higher quality factors and even 'anti-Q-slope' in some cases. However, it is not entirely clear the role that each of these impurities plays in the performance enhancement of the cavities. It has been suggested that interstitial N within the first few nm of the surface is solely responsible for the observed enhancement, but little work has been done on the role of C and O. Because both C and O are abundant in much higher quantities than N near the surface, it is important to understand whether they are beneficial or detrimental to cavity performance. We provide further insight into the effects of C and O on cavity performance by baking in an ambient atmosphere rich in CO2 as opposed to N2.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF041

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF042

A Computational Method for More Accurate Measurements of the Surface Resistance in SRF Cavities

SRF, operation, niobium, radio-frequency

2458

J.T. Maniscalco, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The principal loss mechanism for superconducting RF cavities in normal operation is Ohmic heating due to the microwave surface resistance in the superconducting surface. The typical method for calculating this field-dependent surface resistance R_s(H) from RF measurements of quality factor Q₀ implicitly returns a weighted average of R_s over the surface as a function of peak surface magnetic field H, not the true value of R_s as a function of the local magnitude of H. In this work we present a computational method to convert a measured Q₀ vs. H_peak to a more accurate R_s vs. H_local, given knowledge about cavity geometry and field distribution.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF043

Frequency Tuner Development at Cornell for the RAON Half Wave Resonators

cryogenics, cryomodule, controls, operation

2461

M. Ge, F. Furuta, T. Gruber, S.W. Hartman, M. Liepe, J.T. Maniscalco, T.I. O'Connell, P.J. Pamel, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
B.H. Choi, J. Joo, J.W. Kim, W.K. Kim, J. Lee, I. Shin
IBS, Daejeon, Republic of Korea

The superconducting half-wave-resonators for the RAON project require a slow frequency tuner that can provide at least 80 kHz tuning range. Cornell University has designed, prototyped, and tested a tuner for these half-wave-resonators. In this paper, we present the tuner design, prototype fabrication, test insert preparation, long-term testing and tuner performance test results at cryogenic temperature. The performance of the tuner is analyzed in detail.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF043

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF044

Updates on the DC Field Dependence Cavity

niobium, multipactoring, SRF, simulation

2465

J.T. Maniscalco, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Work at Cornell has demonstrated good agreement between a theoretical model by A. Gurevich of the anti-Q-slope (a field-dependent decrease of the microwave surface resistance) and experimental results from impurity-doped niobium. As a corollary, the model predicts that a strong DC magnetic field applied parallel to the RF surface will produce a similar decrease in surface resistance. In order to explore this prediction for many materials, we have designed a new coaxial cavity with a strong, uniform DC field superimposed over a weak RF field on a removable and replaceable niobium sample. Here we present updates on the progress of this new cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF044

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF045

Performance of the Prototype SRF Half-Wave-Resonators Tested at Cornell for the RAON Project

SRF, multipactoring, pick-up, radiation

2468

M. Ge, F. Furuta, T. Gruber, S.W. Hartman, M. Liepe, J.T. Maniscalco, T.I. O'Connell, P.J. Pamel, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
B.H. Choi, J. Joo, J.W. Kim, W.K. Kim, J. Lee, I. Shin
IBS, Daejeon, Republic of Korea

Two prototype superconducting half-wave-resonator (162.5 MHz and β=0.12) for the RAON project have been successfully tested at Cornell University. Detailed vertical performance testing included (1) test of the bare cavity without the helium tank, and (2) test of the dressed cavity with a helium tank. In this paper, we report on the development of the test infrastructure, test results, and performance data analysis, showing that the specifications for RAON were met.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF046

Modeling of the Frequency and Field Dependence of the Surface Resistance of Impurity-Doped Niobium

niobium, experiment, ECR, SRF

2471

J.T. Maniscalco, P.N. Koufalis, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The anti-Q-slope, a field-dependent decrease in surface resistance observed in impurity-doped niobium, has been investigated extensively in 1.3 GHz cavities. New early research into this effect has recently been performed at higher and lower frequencies, revealing an additional dependence on frequency: the anti-Q-slope is stronger at higher frequencies and weaker at lower frequencies. Several models have been proposed to explain the anti-Q-slope, with varying success in this new frequency-dependent regime. In this work, we analyze recent experimental data from a low-temperature-doped 1.3 GHz cavity and a high-temperature nitrogen-doped 2.6 GHz cavity and discuss the implications of these results on the proposed models.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF046

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF047

Performance of Samples With Novel SRF Materials and Growth Techniques

SRF, superconducting-RF, niobium, site

2475

T.E. Oseroff, M. Ge, M. Liepe, J.T. Maniscalco, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S.R. McNeal
Ultramet, Pacoima, California, USA
M.J. Sowa
Veeco-CNT, Medford, USA

Novel materials are currently being studied in an attempt to push accelerating superconducting RF cavities to support higher accelerating fields and to operate with lower power loss. Growing layers of these materials of the quality necessary has proven to be difficult. In this work, we present the SRF performance of planar samples of the promising materials, NbN and Nb¬3Sn, grown using atomic layer deposition (ALD) and chemical vapor deposition (CVD) respectively. Results are promising.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF047

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF050

Update on Nb3Sn Progress at Cornell University

niobium, SRF, accelerating-gradient, site

2479

R.D. Porter, J. Ding, D.L. Hall, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
T.A. Arias, P. Cueva, D.A. Muller, N. Sitaraman
Cornell University, Ithaca, New York, USA

Niobium-3 Tin (Nb3Sn) is the most promising alternative material for SRF accelerator cavities. The material can achieve higher quality factors, higher temperature operation and potentially higher accelerating gradients compared to conventional niobium. Cornell University has a leading program to produce 2 - 3 micrometer thick coatings of Nb3Sn on Nb for SRF applications using vapor diffusion. This program has been the first to produce quality factors higher than achievable with conventional Nb at usable accelerating gradients. Here we present an update on progress at Cornell University, including studies of the formation of the Nb3Sn layer, density functional theory calculations of Nb3Sn growth, and designs for a sample host cavity for measuring the quench field of Nb3Sn.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF050

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF054

Design and Status of the MicroTCA.4 Based LLRF System for TARLA

controls, LLRF, hardware, operation

2490

Gumus, C. Gumus, M. Hierholzer, K.P. Przygoda, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
A.A. Aksoy, A. Aydin
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey

The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is constructing a 40 MeV Free Electron Laser with continuous wave (CW) RF operation. In order to control and monitor the four superconducting (SC) TESLA type cavities as well as the two normal conducting (NC) buncher cavities, a MicroTCA.4 based LLRF system is foreseen. This highly modular system is further used to control the mechanical tuning of the SC cavities by control of piezo actuators and mechanical motor tuners. This paper focuses on giving brief overview on hardware and software components of LLRF control of TARLA, as well as updates on the ongoing integration tests at DESY.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF054

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF058

Anomaly Detection for Cavity Signals - Results from the European XFEL

flattop, FEL, beam-loading, simulation

2502

A.S. Nawaz, S. Pfeiffer
DESY, Hamburg, Germany
G. Lichtenberg
HAW, Hamburg, Germany
P. Rostalski
Institute for Electrical Engineering in Medicine, Lübeck, Germany

The data throughput of the European XFEL DAQ is about 1.5 Gb/s. Data depicting the cavity signal behavior is currently only saved manually. This either happens, when cavity tests are being performed, or an operator detects a fault in the cavity system, that has to be further investigated. Those instances of interest are neither systematically nor automatically stored. It can therefore be assumed that unwanted or degraded cavity behavior is detected late or not at all. It is proposed to change the focus from detecting known faults (such as quenches) to additionally detect anomalies in the cavity system behavior. In order to detect anomalies in the cavity signals, an algorithm is proposed using a cavity model. It aims on finding those data sets, which diverge from the nominal cavity behavior, saving those instances for later analysis. The nominal behavior is defined by the cavity electromagnetic resonance model with beam loading as well as the model for the mechanical oscillations due to the Lorentz Forces. By using such an approach, the detection of anomalies, as well as faults could be automated. This contribution aims to summarize the influence of beam loading on the detection and gives examples for anomalies that were found in several cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF058

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF062

Simulation of Cavity Conditioning for the Diamond SCRF Cavity

GUI, coupling, simulation, operation

2509

S.A. Pande, C. Christou, P. Gu
DLS, Oxfordshire, United Kingdom

Diamond SCRF cavities are pulse conditioned every week in order to keep them operating reliably. During conditioning, the cavities are detuned in order to sweep the standing wave through the waveguide. To match these cavities at lower voltage (typically < 1.4 MV) and at higher power, 3 stub tuners are used in the waveguide feed. Simulations with CST studio show that a strong SW field exists between the RF window and the matching posts. As the cavity is detuned the electric field maximum passes through the window causing heating of the ceramic. Temperature measurements with thermal camera reveal that the temperature of the window increases to maximum when the cavity is detuned towards higher frequency. Based on the simulation results and the measurements, it was decided to reduce the conditioning voltage. These results are summarised.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF062

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF065

High Efficiency, High Power, Resonant Cavity Amplifier For PIP-II

coupling, impedance, network, operation

2518

M.P.J. Gaudreau, N. Butler, D.B. Cope, P. H. Gordon, E.G. Johnson, M.K. Kempkes, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: Funded under US DOE grant no. DE-SC0015780
Diversified Technologies, Inc. (DTI) is developing an integrated resonant-cavity combined solid-state amplifier for the Proton Improvement Plan-II (PIP-II) at Fermilab. The prototype has demonstrated multiple-transistor combining at 71% efficiency, at 675 watts per transistor at 650 MHz. The design simplifies solid-state transmitters to create straightforward scaling to high power levels. A crucial innovation is the reliable "soft-failure" mode of operation; a failure in one or more of these myriad combined transistors has negligible performance impact. The design couples the transistor drains directly to the cavity without first transforming to 50 Ohms, avoiding the otherwise-necessary multitude of circulators, cables, and connectors. DTI's design increases the power level at which it is cost-effective to employ a solid-state transmitter. DTI is upgrading the system to accommodate more transistors in each cavity module, and then will design and build a complete 100 kW-class transmitter which will consist of four such cavity modules and a combiner.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF065

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF068

Inexpensive Brazeless Accelerator Prototype

gun, vacuum, operation, electron

2528

S.P. Antipov, R.A. Kostin, S.V. Kuzikov
Euclid TechLabs, LLC, Solon, Ohio, USA
A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

Funding: DOE SBIR
A simple, inexpensive way to manufacture a standard radio frequency (RF) driven particle accelerator is presented. The simplification comes from two innovations: utilization of LCLS gun type RF design to avoid an expensive brazing process and copper plating of stainless steel that further reduces manufacturing cost. This is realized by a special structure design where accelerating structure cells are made out of copper plated stainless steel with knife edges and structure irises - copper disks acts also as gaskets for vacuum and RF seal. Besides the reduced cost, brazeless assembly allows integration of effective cooling and magnet optics elements into accelerator cells. Here we report on manufacturing and testing of brazeless accelerator prototype.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF068

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF069

High Shunt Impedance Accelerating Structure with Distributed Microwave Coupling

coupling, GUI, distributed, impedance

2531

S.P. Antipov, R.A. Kostin, S.V. Kuzikov
Euclid TechLabs, LLC, Solon, Ohio, USA
V.A. Dolgashev
SLAC, Menlo Park, California, USA

Funding: DOE SBIR
Conventional traveling wave or pi-phase advance standing wave structures use coupling of the microwave power through the beam pipe. This feature constrains the cavity shunt impedance (efficiency) to relatively small values. As microwave power flows through the accelerating cells in such structures, the probability of breakdown in high gradient operation is greatly increased. In this paper we present results from an accelerating structure prototype with distributed microwave coupling, an approach invented at SLAC. These structures include one or more parallel waveguides which are loaded by accelerating cavities. In this configuration accelerating cavities are fed independently and completely isolated at the beam pipe. Thus there is no microwave power flow through the accelerating cavity, making this geometry favorable for high gradient operation and maximizing the shunt impedance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF069

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF074

High Power Conditioning of X-Band RF Components

operation, vacuum, hardware, GUI

2545

N. Catalán Lasheras, H. Damerau, R.L. Gerard, A. Grudiev, G. McMonagle, J. Paszkiewicz, A. Solodko, I. Syratchev, B.J. Woolley, W. Wuensch, V. del Pozo Romano
CERN, Geneva, Switzerland
T.G. Lucas, M. Volpi
The University of Melbourne, Melbourne, Victoria, Australia
S. Pitman
Lancaster University, Lancaster, United Kingdom
A. Vnuchenko
IFIC, Valencia, Spain

As part of the effort to qualify CLIC accelerating struc-tures prototypes, new X-band test facilities have been built and commissioned at CERN in the last years. In this context, a number of RF components have been designed and manufactured aiming at stable operation above 50 MW peak power and several kW of average power. All of them have been tested now in the X-band facility at CERN either as part of the facility or in dedicated tests. Here, we describe shortly the main design and manufac-turing steps for each component, the testing and eventual conditioning as well as the final performance they achieved.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF074

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF078

Assembly of the DQW Crab Cavity Cryomodule for SPS Test

cryomodule, vacuum, controls, alignment

2561

M. Garlaschè, K. Artoos, R. Calaga, O. Capatina, T. Capelli, N. El Kbiri, D. Lombard, P.F. Marcillac, P. Minginette, M. Narduzzi, L.R.A. Renaglia, J. Roch, J.S. Swieszek
CERN, Geneva, Switzerland
A. Krawczyk, B. Prochal
IFJ-PAN, Kraków, Poland

RF Crab Cavities are an essential part of the High Luminosity Upgrade of the LHC accelerating complex. Two concepts of such superconducting systems are being developed: the Double Quarter Wave (DQW) and the RF Dipole (RFD). A prototype cryomodule - hosting two DQW cavities - has been fabricated and assembled for validation tests to be carried out in the Super Proton Synchrotron (SPS) at CERN. An overview of the main cryomodule components is presented, together with the system features and main fabrication requirements. The preparatory measures for cryomodule assembly, the execution and lessons learned are also discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF078

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK007

INFN-LASA Design and Prototyping Activity for PIP-II

HOM, coupling, operation, linac

2640

A. Bignami, M. Bertucci, A. Bosotti, J.F. Chen, P. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
S. Pirani
ESS, Lund, Sweden

The design of the PIP-II medium-β, 5-cell, 650 MHz SRF elliptical cavity and the first steps of its prototyping activity are here presented. A design based on a three dies fabrication model has been chosen and fully characterized in terms of electromagnetic and mechanical parameters. Goal of the optimization has been to realize a highly performant cavity for CW operation with reasonably good performances when pulsed. A prototyping phase started with the production of three single-cell cavities used to validate the LASA model and to develop an optimal recipe for RF surface treatment according to the state-of-the-art of the high-Q frontier.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK007

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK008

In-Depth Analysis of the Vertical Test Results of the Third-Harmonic Cavities for the E-XFEL Injector

FEL, experiment, feedback, SRF

2644

M. Bertucci, A. Bignami, A. Bosotti, J.F. Chen, C.G. Maiano, P. Michelato, L. Monaco, R. Paparella, P. Pierini, D. Sertore
INFN/LASA, Segrate (MI), Italy
C.G. Maiano, P. Pierini
ESS, Lund, Sweden
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

The results of the vertical tests performed at LASA on the 3.9 GHz third-harmonic cavities for the E-XFEL injector are here discussed. Analysis of experimental data allows to confirm that such high frequency cavity, prepared with standard BCP treatment and 800°C annealing treatment, suffers an intrinsic performance limitation at around 22 MV/m (@ 2 K) due to a global thermal dissipation mechanism. A quantitative interpretation of the high field Q slope is also presented according to the latest theoretical models of field-dependent surface resistance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK008

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK010

LCLS-II Cryomodules Production at Fermilab

cryomodule, vacuum, FEL, controls

2652

T.T. Arkan, J.N. Blowers, C.M. Ginsburg, C.J. Grimm, J.A. Kaluzny, A. Lunin, Y.O. Orlov, K.S. Premo, R.P. Stanek, G. Wu
Fermilab, Batavia, Illinois, USA

Funding: DOE
LCLS-II is a planned upgrade project for the linear coherent light source (LCLS) at SLAC. The LCLS-II linac will consist of thirty-five 1.3 GHz and two 3.9 GHz superconducting RF continuous wave (CW) cryomodules that Fermilab and Jefferson Lab are currently producing in collaboration with SLAC. The LCLS-II 1.3 GHz cryomodule design is based on the European XFEL pulsed-mode cryomodule design with modifications needed for CW operation. Two prototype cryomodules had been assembled and tested. After prototype cryomodule tests, both laboratories have increased cryomodule production rate to meet the challenging LCLS-II project installation schedule requirements of approximately one cryomodule per month per laboratory. Fermilab is at half point for the production, meaning that 6 cryomodules are fully assembled and tested. This paper presents Fermilab Cryomodule Assembly Facility (CAF) infrastructure for the LCLS-II cryomodules assembly, production experience at the half point emphasizing the challenges and mitigations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK012

Update on Plasma Processing R&D for LCLS-II

plasma, HOM, experiment, SRF

2656

P. Berrutti, A. Grassellino, T.N. Khabiboulline, M. Martinello
Fermilab, Batavia, Illinois, USA
M. Doleans, S.-H. Kim, K.E. Tippey
ORNL, Oak Ridge, Tennessee, USA
D. Gonnella, G. Lanza, M.C. Ross
SLAC, Menlo Park, California, USA

Funding: Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
SRF cavities performance preservation is crucial, from vertical test to accelerator operation. Field emission is still one of the main problems to overcome and plasma cleaning has been proven successful by SNS, in cleaning field emitters and increasing the work function of Nb. A collaboration has been established between FNAL, SLAC and ORNL with the purpose of applying plasma processing to LCLS-II cavities, in order to minimize and overcome field emission without affecting the high Q of N-doped cavities. The recipe will follow the neon-oxygen active plasma adopted at SNS, allowing in-situ processing of cavities and cryomodules from hydrocarbon contaminants. A novel method for plasma ignition has been developed at FNAL: a plasma glow discharge is ignited using high order modes to overcome limitations imposed by the fundamental power coupler. The results of experiments on 9-cell LCLS-II cavity are presented, along with plasma ignition studies. In addition the RF system is shown and N-doped Nb samples studies are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK014

A New Design for the Hilumi Radio-Frequency Dipole Bare Cavity

niobium, GUI, resonance, SRF

2659

M. Parise, P. Berrutti, L. Ristori
Fermilab, Batavia, Illinois, USA

Crabbing cavities are one of the technological landmark that will allow the LHC to optimize its per-formance and maximize its integrated luminosity by allowing a head-on collision between the bunches despite the non-zero crossing angle. A total of 8 crab cavities will be installed in the interaction region of each of the two experiments, ATLAS and CMS. In the last years, the two types of crab cavities were de-signed, built and tested under the US-LARP R&D pro-gram. Horizontal crabbing is obtained with a radio-frequency dipole cavity (RFD) designed by Old Do-minion University (ODU), SLAC and Fermilab (FNAL). In this paper a new mechanical design, that uses passive stiffeners, is presented. This design leads to a decrease of the Lorentz Force Detuning frequency shift, satisfy the requirements on pressure sensitivity, validate the structural integrity and increase the tuner sensitivity and the maximum elastic tuning range. Furthermore, it will be possible to greatly simplify the shape of the magnetic shield and Helium vessel with respect to the current design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK014

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK015

Optimization of Vertical Electro-Polishing Process: Experiments with Updated Cathode on Single-Cell Cavity and Performance Achieved in Vertical Test

cathode, SRF, linac, superconductivity

2662

F. Éozénou, L. Maurice
CEA/DSM/IRFU, France
P. Carbonnier, C. Madec, Th. Proslier, C. Servouin
CEA/DRF/IRFU, Gif-sur-Yvette, France
V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

Marui Galvanizing Co.Ltd., and CEA have been studying Vertical Electro-Polishing (VEP) on Nb single-cell accelerating superconducting accelerator cavity with the goal of mass-production and cost-reduction, in collaboration with KEK within TYL-FJPPL Particle Physics Laboratory. Marui has invented and patented a rotative cathode called ‘i-Ninja'. The version 5 has been tested for the first time in Europe at CEA Saclay. The four wings of the cathode remove efficiently, bubbles of hydrogen, and the chosen parameters make it possible to achieve better surface and uniform material removal compared to VEP with a fixed cathode. The effect of the temperature of the cavity walls on current oscillations has been precisely studied. Two single-cell cavities have been electro-polished and tested at 2 K in vertical cryostat and the results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK016

New Insight on Nitrogen Infusion Revealed by Successive Nanometric Material Removal

SRF, accelerating-gradient, factory, niobium

2665

M. Checchin, A. Grassellino, M. Martinello, O.S. Melnychuk, S. Posen, A.S. Romanenko, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA

In this study we present new insight on low temperature nitrogen infusion on bulk niobium superconducting radio-frequency (SRF) cavities. Nitrogen infusion is a thermal treatment recently discovered at Fermilab that allows to reach high accelerating gradients, of the order of 45MV/m, with high Q-factors, of the order of 2 · 10¹⁰. Detailed depth dependent RF studies (by means of subsequent HF rinses) and comparisonwith SIMS results pinpointed interstitial nitrogen as the responsible for the improved performance and uncovered the extension of its profile inside the material.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK016

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML001

Passive Microphonics Mitigation during LCLS-II Cryomodule Testing at Fermilab

cryomodule, cryogenics, controls, resonance

2668

J.P. Holzbauer, B.E. Chase, J. Einstein-Curtis, B.J. Hansen, E.R. Harms, J.A. Kaluzny, A.L. Klebaner, M.W. McGee, Y.O. Orlov, T.J. Peterson, Y.M. Pischalnikov, W. Schappert, R.P. Stanek, J. Theilacker, M.J. White, G. Wu
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The LCLS-II project calls for cryomodule production and testing at both Fermilab and JLab. Due to low beam loading and high cavity quality factor, the designed peak detuning specification is 10 Hz. Initial testing showed peak detuning up to 150 Hz with a complex and varying time-structure, showing both fast (1-2 second) and slow (1-2 hour) drifts in amplitude and spectrum. Extensive warm and cold testing showed Thermoacoustic Oscillations in the cryogenic valves were the primary source of the microphonics. This was mitigated by valve wipers and valve re-plumbing, resulting in a greatly improved cavity detuning environment. Additional modifications were made to the cavity mechanical supports and Fermilab test stand to improve detuning performance. These modifications and testing results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML001

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML002

Design of 650 MHz Tuner for PIP-II Project

interface, simulation, experiment, linac

2671

Y.M. Pischalnikov, S. Cheban, J.C. Yun
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The Proton Improvement Plan (PIP) II project at Fermilab is a proton driver linac which will use of five different cavity geometries including a 650 MHz 5-cell elliptical cavities that will operate in RF-pulse mode. Detuning of these cavities by Lorentz Forces will be large and strongly depend of the stiffness of the cavity's tuner. First prototype tuner built and tested warm [1,2]. Measured stiffness of the prototype tuner was below 30kN/mm instead of expected from simulation 70kN/mm [2]. Significant effort has been invested into understanding discrepancy between simulation and experimental data that led to newest tuner design. Updated 'dressed cavity-helium vessel-tuner' model provided consistent results between ANSYS simulations and experiment results. Modified tuner design and analysis in limitations for overall 'cavity/tuner system' stiffness will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML002

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML003

Precision Q0 Measurement of an SRF Cavity with a Digital RF Techniques

coupling, SRF, impedance, GUI

2674

J.P. Holzbauer, B.M. Hanna, Y.M. Pischalnikov, W. Schappert, D.A. Sergatskov, A.I. Sukhanov
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Direct measurement of the quality factor of SRF cavity using traditional RF techniques is essential for cavity production and development. Systematic effects of the measurement can contribute significant amounts of error to these measurements if not accounted for. This paper will present measurements taken at Fermilab using a digital RF system to characterize and correct for these systematic effects and directly measure the quality factor versus gradient curve for a single spoke resonator in the Spoke Test Cryostat at Fermilab. These measurements will be compared to traditional calorimetric measurements, and a discussion of improving/extending these techniques to other testing situations will be included.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML004

Production Tuner Testing for LCLS-II Cryomodule Production

cryomodule, LLRF, interface, SRF

2678

J.P. Holzbauer, Y.M. Pischalnikov, W. Schappert, J.C. Yun
Fermilab, Batavia, Illinois, USA
C. Contreras-Martinez
FRIB, East Lansing, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
LCLS-II 1.3 GHz cryomodule production is well underway at Fermilab. Several dozen cavity/tuner systems have been tested, including tuning to 1.3 GHz, cold landing frequency, range/sensitivity of the slow tuner, and range/sensitivity of the fast tuner. All this testing information as well as lessons learned from tuner installation will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML004

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML005

Testing of SSR1 Production Tuner for PIP-II

linac, SRF, niobium, cryomodule

2681

J.P. Holzbauer, D. Passarelli, Y.M. Pischalnikov
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The PIP-II project at Fermilab is a proton driver linac calling for the use of five different, novel cavity geometries. Prototyping at Fermilab is in the advanced stages for the low-beta single-spoke resonator (SSR1) and associated technologies. A production tuner design has been fabricated and tested, both warm and cold in the Spoke Test Cryostat (STC). This paper will present the detailed studies on this tuner, including slow motor/piezoelectric tuner range and hysteresis as well as dynamic mechanical system characterization.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML005

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML006

Modified Slow Tuner Design for Cavity 1 Inside LCLS II Cryomodules

cryomodule, interface, SRF, simulation

2684

Y.M. Pischalnikov, T.T. Arkan, S. Cheban, J.P. Holzbauer, J.A. Kaluzny, Y.O. Orlov, J.C. Yun
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Initial LCLS-II cryomodule testing at Fermilab showed microphonics on the furthest upstream cavity (number 1) at least factor 2 larger than on the rest of the cavities. Testing indicated that this was a difference in the mechanical support of cavity 1, not a local acoustic source. Further investigation pointed to the upstream beam-pipe of the cavity 1. The upstream cavity flange has a solid spool piece connection to the beamline gate valve unlike the other cavities, which all connect through bellows. The gate valve's weight is supported by sliding system (free in z-axis) connected to large diameter Helium gas return pipe. The tuner design was modified to transform interface between cavity#1 and gate valve. Arms of the tuner for cavity 1 were extended and became the support structure for gate valve, eliminating the connection to the helium return pipe. Modification of the tuner design and results in microphonics mitigations will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML007

Active Microphonics Compensation for LCLS-II

controls, resonance, LLRF, cryomodule

2687

J.P. Holzbauer, B.E. Chase, J. Einstein-Curtis, Y.M. Pischalnikov, W. Schappert
Fermilab, Batavia, Illinois, USA
L.R. Doolittle, C. Serrano
LBNL, Berkeley, California, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Testing of early LCLS-II cryomodules showed microphonics-induced detuning levels well above specification. As part of a risk-mitigation effort, a collaboration was formed between SLAC, LBNL, and Fermilab to develop and implement active microphonics compensation into the LCLS-II LLRF system. Compensation was first demonstrated using a Fermilab FPGA-based development system compensating on single cavities, then with the LCLS-II LLRF system on single and multiple cavities simultaneously. The primary technique used for this effort is a bank of narrowband filter set using the piezo-to-detuning transfer function. Compensation automation, optimization, and stability studies were done. Details of the techniques used, firmware/software implementation, and results of these studies will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML007

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML008

Tuner Testing of a Dressed 3.9 GHz Cavity for LCLS-II at Fermilab

SRF, operation, background, FEL

2690

J.P. Holzbauer, S. Aderhold, T.N. Khabiboulline, Y.M. Pischalnikov, W. Schappert, J.C. Yun
Fermilab, Batavia, Illinois, USA
C. Contreras-Martinez
FRIB, East Lansing, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Fermilab is responsible for the design of the 3.9 GHz cryomodule for LCLS-II. Integrated acceptance testing of a dressed 3.9 GHz cavity for the LCLS-II project has been done at the Fermilab Horizontal Test Stand. This test included a slim blade tuner (based on INFN & XFEL designs) with integrated piezoelectric fast/fine tuner. This paper will present results of the mechanical setup, cold testing, and cold function of this tuner including fast and slow tuner range, sensitivity, and hysteresis.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML008

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML010

Operation Regime Analysis of Conduction Cooled Cavities Through Multi-Physics Simulation

operation, SRF, simulation, niobium

2697

R.A. Kostin, R. Dhuley, M.G. Geelhoed, R.D. Kephart, T.K. Kroc, O.V. Prokofiev, J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Department of Energy
Euclid Techlabs in collaboration with Fermilab IARC (Batavia, IL) is developing industrial superconducting 10MeV electron linac. Conduction cooling is used for cooling instead of liquid helium bath to simplify linac maintenance. The cavity linked to commercially available cryo-cooler cold head through highly conductive aluminium strips. However, this solution raises a problem of contact thermal resistance. This paper shows some results of Comsol multyphysics simulations of the cavity cooling by AL strips. Some insight was obtained on the acceptable range of contact resistance. Operation regimes were obtained at different accelerating gradients and cavity temperatures. The results of simulation are presented and discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML010

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML011

Garnet Ring Measurements for the Fermilab Booster 2nd Harmonic Cavity

booster, controls, solenoid, simulation

2700

R.L. Madrak, J.E. Dey, K.L. Duel, J. Kuharik, A.V. Makarov, W. Pellico, J. Reid, G.V. Romanov, M. Slabaugh, D. Sun, C.-Y. Tan, I. Terechkine
Fermilab, Batavia, Illinois, USA

A perpendicularly biased tuneable 2nd harmonic cavity is being constructed for use in the Fermilab Booster. The cavity's tuner uses National Magnetics AL800 garnet as the tuning media. For quality control, the magnetic properties of the material and the uniformity of the properties within the tuner must be assessed. We describe two tests which are performed on the rings and on their corresponding witness samples.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML011

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML012

Progress on the Construction of the Perpendicularly Biased 2nd Harmonic Cavity for the Fermilab Booster

HOM, booster, damping, impedance

2703

R.L. Madrak, J.E. Dey, K.L. Duel, M.R. Kufer, J. Kuharik, A.V. Makarov, R.D. Padilla, W. Pellico, J. Reid, G.V. Romanov, M. Slabaugh, D. Sun, C.-Y. Tan, I. Terechkine
Fermilab, Batavia, Illinois, USA

A perpendicularly biased tuneable 2nd harmonic cavity, designed for the Fermilab Booster, is being assembled for testing this summer (2018). The cavity will work at twice the frequency of the fundamental cavities, and will be on only during the injection and transition (or extraction) periods. The main purpose of adding this cavity is to improve beam capture and reduce losses as required by Fermilab's Proton Improvement Plan (PIP). After three years of testing and optimization, the cavity design has now been finalized and all constituent parts have been received. We report on the cavity final design and on the status of the construction.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML013

Anti-Q-slope enhancement in high-frequency niobium cavities

ECR, niobium, SRF, experiment

2707

M. Martinello, S. Aderhold, S.K. Chandrasekaran, M. Checchin, A. Grassellino, O.S. Melnychuk, S. Posen, A.S. Romanenko, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA

N-doped 1.3 GHz niobium cavities showed for the first time the so-called anti-Q-slope, i.e. the increasing of the Q-factor as a function of the accelerating field. It was verified that the anti-Q-slope is consequence of the decreasing of the temperature-dependent component of the surface resistance as a function of the field. This trend is opposite compared to the increasing of the surface resistance previously observed in 1.3 GHz standard (EP, BCP, 120 C baked) niobium cavities. The effect of the different state-of-the-art surface treatments on the field dependence of the surface resistance is studied for 650 MHz, 1.3 GHz, 2.6 GHz and 3.9 Ghz cavities. This proceeding shows that the field dependence of the temperature-dependent component of the surface resistance has a strong frequency dependence and that the anti-Q-slope may appear even in clean niobium cavities if the resonant frequency is high enough, suggesting new routes toward the understanding of the anti-Q-slope effect.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML013

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML014

Tooling Systems for the Assembly and Integration of the SSR1 Cryomodule for PIP-II Project at Fermilab

cryomodule, solenoid, vacuum, insertion

2710

D. Passarelli, F. Di Ciocchis, M. Parise, V. Roger
Fermilab, Batavia, Illinois, USA

In this paper we present the assembly strategy and tooling design for the SSR1 cryomodule from the cavity string to the final module. Several challenging aspects were considered to minimize undesired stresses on critical components, to preserve the alignment of cavities and solenoids during final assembly, and ultimately to meet the technical requirements of the PIP-II project at Fermilab.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML014

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML015

Preparation and Qualification of Jacketed SSR1 Cavities for String Assembly at Fermilab

vacuum, cryomodule, multipactoring, controls

2714

D. Passarelli, P. Berrutti, S.K. Chandrasekaran, J.P. Ozelis, M. Parise, L. Ristori, A.M. Rowe, A.I. Sukhanov
Fermilab, Batavia, Illinois, USA

The qualification of dressed 325 MHz Single Spoke Resonators type 1 (SSR1) to meet technical requirements is an important milestone in the development of the SSR1 cryomodule for the PIP-II Project at Fermilab. This paper reports the procedures and lessons learned in processing and preparing these cavities for horizontal cold testing prior to integration into a cavity string assembly.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML016

Development of Nb3Sn Coatings for Superconducting RF Cavities at Fermilab

SRF, factory, superconductivity, network

2718

S. Posen, S.K. Chandrasekaran, O.S. Melnychuk, D.A. Sergatskov, B. Tennis, Y. Trenikhina
Fermilab, Batavia, Illinois, USA
J. Lee
NU, Evanston, Illinois, USA

Nb3Sn films are a promising alternative material for su-perconducting RF cavities, with proven high quality factors at medium fields and predictions for increased superheating field as well. In this contribution, we de-scribe the latest results from the Fermilab Nb3Sn SRF program. Early experiments have been focused on single cell 1.3 GHz cavities. We briefly review efforts to bring the parameters used in the coating process into a range where they produce uniform surfaces without regions showing signs of excess tin or thin/uncoated areas. We then present the latest cavity results, after modifications to the coating recipe based on feedback from film appear-ance and RF performance. These results show high Q0 at medium fields and a maximum field of ~18 MV/m.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML016

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML022

3.9 GHz Power Coupler Design and Tests for LCLS-II Project

simulation, resonance, cryomodule, diagnostics

2727

N. Solyak, I.V. Gonin, C.J. Grimm, E.R. Harms, T.N. Khabiboulline, A. Lunin, O.V. Prokofiev, G. Wu
Fermilab, Batavia, Illinois, USA

LCLS-II linac requires two 3.9 GHz cryomodules (eight cavities per CM), operating up to 16MV/m in cw regime. Fermilab has designed and built few prototypes of the cavity and auxiliaries and tested them at the vertical and horizontal cryostats. Fundamental power coupler, based on existing design (FLASH, XFEL) was redesign for 2kW average power. We built three prototypes and tested them at room temperature test stand. One coupler was assembled on the cavity and tested at horizontal cryostat as part of design verification program. Test results and comparison with simulations are discussed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML023

Design and Test Results of the 3.9 GHz Cavity for LCLS-II

radiation, cryomodule, operation, FEL

2730

N. Solyak, S. Aderhold, S.K. Chandrasekaran, C.J. Grimm, T.N. Khabiboulline, A. Lunin, O.V. Prokofiev, G. Wu
Fermilab, Batavia, Illinois, USA

The LCLS-II project uses sixteen 3.9 GHz superconduct-ing cavities to linearize energy distribution before the bunch compressor. To meet LCLS-II requirements origi-nal FNAL design used in FLASH and XFEL was signifi-cantly modified to improve performance and provide reliable operation up to 16 MV/m in cw regime [1-3]. Four prototype cavities were built and tested at vertical cryo-stat. After dressing, one cavity was assembled and tested at horizontal cryostat as part of design verification pro-gram. All auxiliaries (magnetic shielding, power and HOM couplers, tuner) were also re-designed and tested with this cavity. In this paper we will discuss cavity and coupler design and test results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML023

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML031

The New Broadband Accelerating System for the SIS18 Upgrade at GSI

operation, impedance, controls, resonance

2755

P. Hülsmann, R. Balß, H. Klingbeil, U. Laier, K.-P. Ningel, C. Thielmann, B. Zipfel
GSI, Darmstadt, Germany

In this contribution, a new SIS18 rf accelerating system is presented whose cavities are based on magnetic alloy materials. The rf system works at harmonic number h=2 (f=0,43- to 2,8 MHz) and provides the necessary accelerating voltage (up to 50kVp) for SIS18 injector operation for FAIR with high intensity heavy ion beams in a fast operation mode with up to three cycles per second. The paper focusses on the cavity part and its cooling issues as well as the broadband characteristics. Due the lossy magnetic alloy ring core filling, which consists of high permeability Finemet FT3M ring cores (HITACHI), the cavities show a broadband behaviour and thus no cavity tuning during the acceleration ramp is necessary. To keep the bandwidth of the cavities as broad as possible they are cooled by a special mineral oil with low permittivity. Also the beam impedance and the power consumption of the rf system are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML031

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML032

The FAIR-SIS100 Bunch Compressor RF Station

power-supply, controls, coupling, electronics

2759

H.G. König, R. Balß, P. Hülsmann, H. Klingbeil, P.J. Spiller
GSI, Darmstadt, Germany
R. Gesche, J.H. Scherer
Aurion Anlagentechnik GmbH, Seligenstadt, Germany
A. Morato, C. Morri, G.T. Taddia
OCEM, Valsamoggia, Italy

In the frame of the Facility for Antiproton and Ion Research (FAIR) 9 bunch compressor RF stations were ordered for the first stage of realization of the SIS100 synchrotron. For RF gymnastics referred to as bunch rotation, one RF station has to provide a sudden rise in gap voltage of up to 40 kVp within less than 30 μs. The system is designed for a maximum RF burst of 3 ms per second. The RF frequency will be pre-selectable between 310 kHz and 560 kHz at a harmonic number of h=2 with respect to the beam. Compressed bunches with a peak current > 150 A and a width < 50 ns are the goal. For this purpose, a 1.218 m long cavity was designed using iron-based magnetic alloy cores. Variable vacuum capacitors are attached for tuning. The cavity is driven by a cross-coupled push-pull tetrode amplifier. This scheme minimizes the influence of the tetrode's DC current at the working point to the cores. The energy for the pulsed system is stored in a relatively small capacitor bank which will be charged semi-continuously and a voltage-stabilizing device is added. Cavity and power amplifier were realized by AURION Anlagentechnik GmbH ' the power supply unit is designed and built by OCEM Power Electronics.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML033

The FAIR-SIS100 Accelerating RF Station

controls, feedback, operation, power-supply

2762

H.G. König, R. Balß, H. Klingbeil, U. Laier, D.E.M. Lens, P.J. Spiller
GSI, Darmstadt, Germany
G. Blokesch, F. Wieschenberg
Ampegon PPT GmbH, Dortmund, Germany
K. Dunkel, M. Eisengruber, J.H. Hottenbacher
RI Research Instruments GmbH, Bergisch Gladbach, Germany
C. Hiltbrunner
Ampegon AG, Turgi, Switzerland

For the Facility for Antiproton and Ion Research (FAIR) 14 ferrite loaded accelerating RF stations are planned for the first stage of realization of the SIS100 synchrotron. Each RF station has to provide a total peak gap voltage of up to 20 kVp in CW operation - tuneable in the range of 1.1 MHz up to 3.2 MHz to allow ion beam acceleration and beam gymnastics at different harmonic numbers and energy levels in the new facility. Each RF station consists of a tuneable ferrite cavity, a single ended tetrode amplifier and a dedicated power supply and control unit (PSU) ' including two bias current supplies for cavity- and control-grid(G1)-circuit-tuning. The ferrite cavity is based on the SIS18 cavity concept but has to provide a 1.25 times higher gap voltage of 20 kVp over a total length of 3 meters. The realization is done by a consortium consisting of RI Research Instruments GmbH as consortium leader and manufacturer of the cavity, Ampegon PPT GmbH (for the tetrode amplifier) and Ampegon AG (for the power supply unit). In this contribution, the system design is discussed, and commissioning results are presented. All main parameters are achieved with the RF station described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML033

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML034

Design and Commissioning of the RF System of the Collector Ring at FAIR

controls, power-supply, MMI, operation

2765

U. Laier, R. Balß, A. Dolinskyy, P. Hülsmann, H. Klingbeil, T. Winnefeld
GSI, Darmstadt, Germany
G. Blokesch, F. Wieschenberg
Ampegon PPT GmbH, Dortmund, Germany
K. Dunkel, M. Eisengruber, J.H. Hottenbacher
RI Research Instruments GmbH, Bergisch Gladbach, Germany
C. Morri, M.P. Pretelli, G.T. Taddia
OCEM, Valsamoggia, Italy

The Collector Ring (CR), a storage ring intended to perform efficient cooling of secondary beams, is under construction at GSI in the scope of the FAIR project. The RF system of the CR has to provide a frequency range from 1.1 to 1.5 MHz and pulsed gap voltages of up to 200 kVp (0.2 to 1 Hz, max. 10^-3 duty cycle) and up to 10 kVp in CW operation. Five identical RF stations will be built. Each RF station consists of an inductively loaded cavity, a tetrode based power amplifier, a semiconductor driver amplifier, a switch mode power supply and two digital feedback loops. The main components of the RF station are designed, built and commissioned in close collaboration between GSI and three companies: RI Research Instruments GmbH, Ampegon PPT GmbH and OCEM Energy Technology SRL. In 2016, the first of five RF stations has been integrated at GSI. In 2017 the system was successfully commissioned to demonstrate that all envisaged parameters have been achieved. This contribution will present the requirements imposed the system, the principal design of the overall system as well as of its key components, and the results of the commissioning of the first RF station.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML039

Design of the Two-Gap Superconducting Re-Buncher

heavy-ion, linac, simulation, proton

2779

M. Gusarova, W.A. Barth, S. Yaramyshev
MEPhI, Moscow, Russia
W.A. Barth, S. Yaramyshev
GSI, Darmstadt, Germany
W.A. Barth, M. Miski-Oglu
HIM, Mainz, Germany
M. Basten, M. Busch
IAP, Frankfurt am Main, Germany
M. Gusarova
JINR, Dubna, Moscow Region, Russia

A new design of a spoke cavity for low relative velocities of heavy ions has been elaborated. Simulation results for a 2-gap spoke cavity with a resonance frequency of 216.816 MHz and a relative velocity of 0.07с are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML040

Further Tests on the Final State of the SC 325 MHz CH-Cavity and Coupler Test Bench Update

linac, heavy-ion, framework, SRF

2783

M. Busch, M. Basten, J. List, P. Müller, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany
W.A. Barth, J. List
GSI, Darmstadt, Germany
W.A. Barth
HIM, Mainz, Germany
W.A. Barth
MEPhI, Moscow, Russia

Funding: Work supported by BMBF Contr. No. 05P15RFBA
At the Institute for Applied Physics, Goethe-University Frankfurt, a sc 325 MHz CH-cavity has been developed and successfully tested up to 14.1 mV/m and has now reached the final production stage with the helium vessel welded to the frontal joints of the cavity and final processing steps have been performed. Further tests in a vertical and horizontal environment are being prepared for intensive studies. This cavity is a prototype for envisaged beam tests with a pulsed ion beam at 11.4 AMeV. In this contribution the results of the performed RF tests are being presented. Furthermore, first measurements of the recently installed 217 MHz coupler test bench are shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML040

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML041

Comparative Study of Low Beta Multi-Gap Superconducting Bunchers

linac, heavy-ion, proton, accelerating-gradient

2786

K.V. Taletskiy, W.A. Barth, M. Gusarova, S. Yaramyshev
MEPhI, Moscow, Russia
W.A. Barth, S. Yaramyshev
GSI, Darmstadt, Germany
W.A. Barth, M. Miski-Oglu
HIM, Mainz, Germany
M. Basten, M. Busch
IAP, Frankfurt am Main, Germany
M. Gusarova
JINR, Dubna, Moscow Region, Russia

The results of a comparative study of low beta multi-gap superconducting bunchers for 216.816 MHz and a relative velocity of 0.07с with dedicated limitations of the overall geometrical dimensions are presented. A comparison of electrodynamic, mechanical and thermal properties of 3-gap and 2-gap cavities is shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML041

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML043

RF Simulations of the Injector Section from CH8 to CH15 for MYRRHA

simulation, impedance, resonance, MMI

2790

P. Müller, M. Busch, H. Hähnel, K. Kümpel, D. Mäder, N.F. Petry, H. Podlech
IAP, Frankfurt am Main, Germany

Funding: Work supported by the EU Framework Programme H2020 662186 (MYRTE) and HIC for FAIR
MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) is the first prototype of an accelerator driven nuclear reactor dealing with the transmutation of long-living nuclear waste. Beam quality and reliability are crucial for the reactor. The injector design is done by IAP, Goethe-University, and has been adapted to the final magnet design and voltage distributions. The energy section from 5.87 MeV up to 16.6 MeV has been changed to normal conducting CH cavities as in the lower energy part of the injector. For beam adjustment a 5-gap CH cavity rebuncher at 5.87 MeV as well as two doublet magnets forming the new MEBT-2 section between CH7 and CH8 have been added. Starting parameters for the RF simulations have been given by beam dynamics results calculated with LORASR. RF simulations of these structures consisting of flatness and tuning optimizations will be presented within this contribution.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML043

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML044

Design of HOM Couplers for Superconducting 400 MHz RF Cavities

HOM, collider, proton, simulation

2793

N.F. Petry, M. Busch, K. Kümpel, O. Meusel, H. Podlech
IAP, Frankfurt am Main, Germany

The Future Circular Collider (FCC) is one possible future successor of the Large Hadron Collider (LHC). The proton-proton collider center-of-mass collision energy is set to 100 TeV with a beam current of 0.5 A. To reach this goal a stable acceleration is critical and therefore higher order modes (HOM) need to be damped. To avoid a high power level in the HOM dampers, further described as couplers, the loaded Q-factor should be below 1000 for the cavity with mounted HOM couplers. Besides a low Q-factor the R/Q value should also be in the range of 1 Ω or below. Two different types of couplers are used to achieve a high damping. The two types are a narrowband Hook-type HOM coupler and a broadband Probe-type HOM coupler. The recent results of the design of the HOM couplers attached to a superconducting 400 MHz RF cavity will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML044

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML045

Infrastructure for Superconducting CH-Cavity Preparation at HIM

linac, vacuum, SRF, heavy-ion

2796

T. Kürzeder, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, M. Miski-Oglu, E. Riehn
HIM, Mainz, Germany
K. Aulenbacher, R.G. Heine, T. Stengler
IKP, Mainz, Germany
W.A. Barth, S. Yaramyshev
GSI, Darmstadt, Germany
F. Hug
KPH, Mainz, Germany

A superconducting cw LINAC for heavy ions is currently under development at GSI in Darmstadt and HIM in Mainz. This Linac is based on 217 MHz multigap bulk niobium Crossbar H-mode RF-cavities. In order to treat and prepare RF-cavities with such a complex geometry a new cleanroom facility has been already built at the Helmholtz-Institut in Mainz. All tools and machines inside the cleanroom can handle cavities with up to 800 mm in diameter and with up to 1300 mm in length. In its ISO-class 6 and 4 zones, respectively it features a large ultrasonic and conductance rinsing bath, a high pressure rinsing (HPR) cabinet and a vacuum oven. The HPR cabinet has an inside clearance of 1.4 m. The large cavities sit on a rotating table, while the rising wand moves vertically up and down. Due to the crossbar structure of the RF-cavities the HPR device allows for off axis-rinsing in their quadrants. For RF testing a 52 m² (4 m x 13 m) concrete shielded area with sufficient liquid helium and nitrogen supply is located next to the cleanroom and the cryo-module assembly area. We will report on the new SRF infrastructure in Mainz and the commissioning of the new high pressure rinsing cabinet.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML046

Multipactor Discharge in Superconducting Accelerating CH Cavities

multipactoring, electron, linac, heavy-ion

2800

M. Gusarova, D. I. Kiselev
MEPhI, Moscow, Russia
F.D. Dziuba, T. Kürzeder, M. Miski-Oglu
HIM, Mainz, Germany
M. Gusarova
JINR, Dubna, Moscow Region, Russia

The results of numerical simulations of multipacting discharge in a superconducting accelerating CH cavity are presented in this paper. The localization of multipactor trajectories in the 15-gap 217 MHz superconducting (sc) CH cavity at various levels of accelerating voltage is considered.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML046

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML047

Study on RF Coupler Kicks of SRF Cavities in the BESSY VSR Module

SRF, storage-ring, HOM, GUI

2804

A.V. Tsakanian, T. Mertens
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
H.-W. Glock, J. Knobloch, M. Ries, A.V. Vélez
HZB, Berlin, Germany

The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.7ps) bunches in the storage ring with the standard user optics. This challenging goal requires installation of four new SRF multi-cell cavities (2x1.5GHz and 2x1.75GHz) equipped with strong waveguide HOM dampers ensuring tolerable beam coupling impedance, necessary for stable operation. These cavities will operate at high 20MV/m in CW mode and at the zero-crossing phase according to the accelerating voltage. Consequently the transverse voltages will be maximum and can impact the transverse beam dynamics. The asymmetric character of those transverse kicks are caused by cavity fundamental power couplers (FPC) with strong monopole terms, introducing transverse kick to on-axis particles. Different FPC orientations were analyzed to optimize the net coupler kick from the four cavity chain. The coupler kick strength of each cavity is estimated taking into account accelerating mode amplitudes and phases required for operation in VSR mode.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML047

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML048

HOM Power Levels in the BESSY VSR Cold String

HOM, SRF, simulation, GUI

2808

A.V. Tsakanian, T. Flisgen
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
H.-W. Glock, J. Knobloch, A.V. Vélez
HZB, Berlin, Germany

The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.7ps) bunches in the storage ring. This challenging goal requires installation of four new SRF cavities (2x1.5 GHz and 2x1.75 GHz) in one module for installation in a single straight. These cavities are equipped with strong waveguide HOM dampers necessary for stable operation. The expected HOM power and spectrum has been analyzed for the complete cold string. The cold string is a combination of various elements such as SRF cavities, bellows with and without shielding, warm HOM beampipe absorbers and UHV pumping domes. The presented study is performed for various BESSY VSR bunch filling patterns with 300 mA beam current. The contribution of each component to the total HOM power is presented. In addition the optimization of different cavity arrangements in the module is performed in order to reach the optimal operation conditions with equally distributed power levels along the string and tolerable beam coupling impedance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML048

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML049

The Challenge to Measure nΩ Surface Resistance on SRF Samples

SRF, quadrupole, pick-up, simulation

2812

S. Keckert, T. Junginger, J. Knobloch, O. Kugeler
HZB, Berlin, Germany
T. Junginger
Lancaster University, Lancaster, United Kingdom

Systematic research on fundamental limits of superconducting materials for SRF applications and their intrinsic material properties relevant for use in an accelerator requires studies in a wide parameter space of temperature, RF field and frequency. The Quadrupole Resonator at HZB enables precision measurements on planar samples at temperatures of 1.8 K to >20 K, RF fields of up to 120 mT, and frequencies of 420 MHz, 850 MHz and 1285 MHz. In the past years the capabilities of the setup were studied intensively and developed further. Sources of systematic errors, such as microphonics or misalignment have been identified and eliminated. In this contribution the current status of the QPR and its systematic limitations are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML049

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML051

Improvement of the Chopper System for rf Deflector at the J-PARC Linac

controls, timing, linac, operation

2816

K. Futatsukawa, Z. Fang, Y. Fukui
KEK, Ibaraki, Japan
Y. Sato
Nippon Advanced Technology Co., Ltd., Tokai, Japan
S. Shinozaki
JAEA/J-PARC, Tokai-mura, Japan

In the J-PARC linac, the RF deflector has been operated to kick the wasted beam and to shape the intermediate-pulse like the comb structure. Then about 50% of the beam current is removed by leading the scraper and the rest beam current is injected to the downstream synchrotron ring RCS. The fast rising time and falling time, the cavity with low loading Q value in the chopper system are required to decrease the incomplete kicked beam. However, there was the ringing of the RF field on the chopper cavity, and it influenced the beam rising time. The chopper controllers, which has the fast RF -switch to make the particular RF according to the intermediate-pulses, were improved for the RF falling time by outputting short pulses with inverting phase. The beam study for the new system was successfully done. In this paper, I would like to introduce this system and to show the results of the beam study.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML051

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML055

Simulation Study of Parasitic-Mode Damping Methods for a 1.5-GHz TM020-Mode Harmonic Cavity

impedance, damping, coupling, radiation

2822

N. Yamamoto, S. Sakanaka, T. Takahashi
KEK, Ibaraki, Japan

Design study of parasitic-mode (PM) damped structures has been conducted for the purpose to realize a normal conducting 1.5 GHz harmonic cavity which is based on the TM020 resonant mode*. We have investigated the performances of two PM-damping mechanisms, that are, rod-type antennas** and annular slots. The rod-type antennas locate at the node of electric field of the TM020 mode while the annular slots locate at the node of magnetic field. As a result of 3D electromagnetic simulations, suitable performances of PMs were confirmed by employing either of the PM-damping mechanisms. It was also shown that the slot-type structure is superior in PM-damping performance and in the unloaded Q of the TM020 mode.
* N. Yamamoto et al., IPAC'17, paper THOPIK037; N. Yamamoto Phys. Rev. Accel. Beams, 21, 1, 012001.
** T. Takahashi et al., IPAC'17, paper THPIK036.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML055

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML067

Second Sound Quench Detection on Superconducting Cavities

detector, site, SRF, superconducting-cavity

2843

Z.C. Liu, S. Bai, J. Gao, F.S. He, H.Y. Lin, P. Zhang
IHEP, Beijing, People's Republic of China

Second sound is an effective way to detect the quench position on superconducting cavity. A second sound quench site detection system is under developing for the PAPS. High gradient is very important for superconducting cavity, however it may be limited by quench on the cavity high field region. Quench can be caused by various reasons. To locate the position is the key to reveal the mysteries of quench. Now we are developing the quench position detection system by RTD sensors such as Cernox and OST sensors.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML067

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML078

Development of a Superconducting Double-Spoke Cavity at IMP

accelerating-gradient, SRF, ion-source, niobium

2869

T.C. Jiang, H. Guo, Y. He, C.L. Li, L.B. Liu, T. Tan, P.R. Xiong, Z.M. You, W.M. Yue, S.H. Zhang, S.X. Zhang
IMP/CAS, Lanzhou, People's Republic of China

Superconducting multi-spoke cavities are well-known optional choice for acceleration of heavy ions in medium velocity regimes. The paper describes the design, fabrication and test results of the superconducting double-spoke cavity developed at IMP. After Buffered Chemical Polishing and High pressure Rinsing, one cavity has undergone high gradient RF testing at 4 K in the Vertical Test Stand. We present measurements of the quality factor as a function of accelerating field and maximum field on the surface. Accelerating gradient of more than 15 MV/m is reached with peak electric field of 61 MV/m, and peak magnetic field of 118 mT.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML078

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THXGBD1

The Upgrade of the Advanced Photon Source

lattice, feedback, controls, simulation

2872

M. Borland, M. Abliz, N.D. Arnold, T.G. Berenc, J.M. Byrd, J.R. Calvey, J.A. Carter, J. Carwardine, H. Cease, Z.A. Conway, G. Decker, J.C. Dooling, L. Emery, J.D. Fuerst, K.C. Harkay, A.K. Jain, M.S. Jaski, P.S. Kallakuri, M.P. Kelly, S.H. Kim, R.M. Lill, R.R. Lindberg, J. Liu, Z. Liu, J. Nudell, C.A. Preissner, V. Sajaev, N. Sereno, X. Sun, Y.P. Sun, S. Veseli, J. Wang, U. Wienands, A. Xiao, C. Yao
ANL, Argonne, Illinois, USA
A. Blednykh
BNL, Upton, Long Island, New York, USA

After decades of successful operation as a 7-GeV synchrotron radiation source, the Advanced Photon Source is pursing a major upgrade that involves replacement of the storage ring with an ultra-low emittance multi-bend achromat design. Using a seven-bend hybrid multi-bend achromat with reverse bending magnets gives a natural emittance of 42 pm operated at 6 GeV. The x-ray brightness is predicted to increase by more than two orders of magnitude. Challenges are many, but appear manageable based on thorough simulation and in light of the experience gained from world-wide operation of 3^\text{rd}-generation light sources. The upgraded ring will operate in swap-out mode, which has allowed pushing the performance beyond the limits imposed by conventional operation.

Slides THXGBD1 [14.684 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBD1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THXGBF2

Beam Commissioning of the IFMIF EVEDA Very High Power RFQ

rfq, MMI, vacuum, operation

2902

E. Fagotti, L. Antoniazzi, L. Bellan, D. Bortolato, M. Comunian, A. Facco, M.G. Giacchini, F. Grespan, M. Montis, A. Palmieri, A. Pisent, F. Scantamburlo
INFN/LNL, Legnaro (PD), Italy
B. Bolzon, N. Chauvin, R. Gobin
CEA/IRFU, Gif-sur-Yvette, France
P. Cara
IFMIF/EVEDA, Rokkasho, Japan
H. Dzitko, D. Gex, A. Jokinen, G. Phillips
F4E, Germany
T. Ebisawa, A. Kasugai, K. Kondo, K. Sakamoto, T. Shinya, M. Sugimoto
QST, Aomori, Japan
R. Heidinger, A. Marqueta, I. Moya
Fusion for Energy, Garching, Germany
P. Mereu
INFN-Torino, Torino, Italy
G. Pruneri
Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy
M. Weber
CIEMAT, Madrid, Spain

IFMIF, the International Fusion Materials Irradiation Facility, is an accelerator-based neutron source that will use Li(d, xn) reactions to generate a flux of neutrons with a broad peak at 14 MeV equivalent to the conditions of the Deuterium-Tritium reactions in a fusion power plant. IFMIF is conceived for fusion materials testing. The IFMIF prototype linear accelerator (LIPAc) is jointly developed by Europe and Japan within the IFMIF EVEDA project: it is composed of an ion source, a LEBT, an RFQ, a MEBT and a SC linac, with a final energy of 9 MeV. The 4-vane Radio Frequency Quadrupole (RFQ), developed by INFN in Italy, will accelerate a 130 mA deuteron beam from 0.1 to 5 MeV in continuous wave, for a beam power of 650 kW. The 9.8 m long 175 MHz cavity is composed of 18 x 0.54 m long modules flanged together and aligned within 0.3 mm tolerance. The RFQ was completed, delivered and assembled at the Rokkasho site and is presently under extended RF tests. The second phase of beam commissioning (up to 2.5 MeV/u) was scheduled to start at the end of 2017. Several unexpected issues and incidents significantly delayed the original program, which is however proceeding step by step toward the full achievement of its goals.

Slides THXGBF2 [5.318 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBF2

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THYGBD1

FCC: Colliders at the Energy Frontier

collider, luminosity, hadron, injection

2908

M. Benedikt, F. Zimmermann
CERN, Geneva, Switzerland

The international Future Circular Collider study, launched in 2014, is finalizing a multi-volume conceptual design report. The FCC develops high-energy circular collider options based on a new 100 km tunnel. Long-term goal is a 100 TeV proton-proton collider (FCC-hh). The study also includes a high-luminosity electron-positron collider (FCC-ee), and it also examines lepton-hadron scenarios (FCC-he). Civil engineering and technical infrastructure studies were carried out. Global programs advance the development of high-field superconducting magnet technology based on Nb3Sn, the optimization of a suitable large superconducting RF system, and schemes for synchrotron radiation handling. In addition, the FCC study includes the design of the HE-LHC, housed in the LHC tunnel, and based on the same high-field magnet technology as the FCC-hh. The FCC study further includes an elaboration of the physics cases, including for heavy-ion collisions, and detector concepts, as well as staging and implementation scenarios. The FCC collaboration has grown to more than 120 institutes from 30 countries around the world. This invited talk summarizes the study achievements and the final designs.

Slides THYGBD1 [12.503 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBD1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THYGBE3

RF Controls for High-Q Cavities for the LCLS-II

LLRF, controls, cryomodule, EPICS

2929

C. Serrano, K.S. Campbell, L.R. Doolittle, G. Huang, A. Ratti
LBNL, Berkeley, California, USA
R. Bachimanchi, C. Hovater
JLab, Newport News, Virginia, USA
A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, G. Dalit, J.A. Diaz Cruz, J. Jones, R.S. Kelly, A. McCollough
SLAC, Menlo Park, California, USA
B.E. Chase, E. Cullerton, J. Einstein-Curtis, J.P. Holzbauer, D.W. Klepec, Y.M. Pischalnikov, W. Schappert
Fermilab, Batavia, Illinois, USA
L.R. Dalesio, M.A. Davidsaver
Osprey DCS LLC, Ocean City, USA

Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract n. DE-AC02-76SF00515.
The SLAC National Accelerator Laboratory is building LCLS-II, a new 4 GeV CW superconducting (SCRF) Linac as a major upgrade of the existing LCLS. The LCLS-II Low-Level Radio Frequency (LLRF) collaboration is a multi-lab effort within the Department of Energy (DOE) accelerator complex. The necessity of high longitudinal beam stability of LCLS-II imposes tight amplitude and phase stability requirements on the LLRF system (up to 0.01% in amplitude and 0.01° in phase RMS). This is the first time such requirements are expected of superconducting cavities operating in continuous-wave (CW) mode. Initial measurements on the Cryomodule test stands at partner labs have shown that the early production units are able to meet the extrapolated hardware requirements to achieve such levels of performance. A large effort is currently underway for system integration, Experimental Physics and Industrial Control System (EPICS) controls, transfer of knowledge from the partner labs to SLAC and the production and testing of 76 racks of LLRF equipment.

Slides THYGBE3 [14.383 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBE3

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THYGBF4

Accelerator Physics Advances in FRIB (Facility for Rare Isotope Beams)

linac, MMI, ECR, ECRIS

2950

P.N. Ostroumov, N.K. Bultman, M. Ikegami, S.M. Lidia, S.M. Lund, G. Machicoane, T. Maruta, A.S. Plastun, G. Pozdeyev, X. Rao, J. Wei, T. Xu, T. Yoshimoto, Q. Zhao
FRIB, East Lansing, USA
C.Y. Wong
NSCL, East Lansing, Michigan, USA

Funding: Work supported by the U.S. DOE Office of Science under Cooperative Agreement DE-SC0000661 and the NSF under Cooperative Agreement PHY-1102511, the State of Michigan and Michigan State University.
This paper presents recent developments of accelerator physics related topics for the Facility for Rare Isotope Beams (FRIB) being built at Michigan State University. While extensive beam dynamics simulations including all known errors do not show uncontrolled beam losses in the linac, ion beam contaminants extracted from the ECR ion source together with main ion beam can produce significant losses after the charge stripper. These studies resulted in development of beam collimation system at relatively low energy of 16 MeV/u and room temperature bunchers instead of originally planned superconducting ones. Commissioning of the Front End enabled detailed beam physics studies accompanied with the simulations using several beam dynamics codes. Settings of beam optics devices from the ECR to MEBT has been developed and applied to meet important project milestones. Similar work is planned for the beam commissioning of the first 3 cryomodules in the superconducting linac.

Slides THYGBF4 [11.092 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBF4

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF017

Improvement of RF Field Phase and Amplitude Errors Simulations in TraceWin Code

simulation, linac, diagnostics, beam-losses

2983

D. Uriot
IRFU, CEA, University Paris-Saclay, Gif-sur-Yvette, France

Funding: This work is supported by the European Atomic Energy Community's (EURATOM) H2020 Programme under grant agreement n°662186 (MYRTE project)
RF field phase and amplitude errors are usually not correctly simulated and it is a serious problem especially when in high intensity linear accelerators, the main losses are due to particle leaving the beam acceptance. This new development implemented in TraceWin fixes this issue. The objective is to improve the longitudinal beam dynamics simulation methods, by including more close-to-real models for the cavities tuning procedure. By this way, clear distinction should be done between static and dynamic errors and longitudinal diagnostics accuracy can be clearly defined according to beam dynamics results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF017

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF019

Initial Performance of the Magnet System in the Splitter/Combiner Section of the Cornell-Brookhaven Energy-Recovery Linac Test Accelerator

linac, quadrupole, dipole, optics

2986

J.A. Crittenden, A.C. Bartnik, R.M. Bass, D.C. Burke, J. Dobbins, C.M. Gulliford, Y. Li, D. Sagan, K.W. Smolenski, Turco, J. Turco
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.S. Berg
BNL, Upton, Long Island, New York, USA
D. Jusic
Cornell University, Ithaca, New York, USA

Funding: This work is supported by NSF award DMR-0807731, DOE grant DE-AC02- 76SF00515, and New York State Energy Research and Development Authority.
The Cornell-Brookhaven Energy-recovery Linac Test Accelerator is a four-pass, 150-MeV electron accelerator with a six-cell 1.3 GHz superconducting-RF linear accelerator and a fixed-field alternating-gradient (FFAG) return loop made up of Halbach-style quadrupole magnets. The optics matching between the linear accelerator and the return loop is achieved with a conventional magnet system comprised of 50 dipole magnets and 64 quadrupole magnets in four beamlines at each end of the linac. The 42-, 78-, 114- and 150-MeV electron beams are separated into independent vacuum chambers in order to allow for the path-length adjustment required by energy recovery. We report on the first beam tests of the initial installation of the splitter/combiner section at the exit of the linac. The vacuum system of the 42-MeV S1 line was installed during the first week of April. Nine dipole and four quadrupole magnets were installed and surveyed into position the following week, and the water cooling system was commissioned. A 6-MeV beam passed through the line on April~11 with no need for adjusting pre-set magnet excitation currents. One week later, time-of-flight measurements were used to calibrate and phase the individual superconducting RF cavities. The S1 magnet settings were then scaled up to achieve 5-cavity, 42-MeV operation through the first nine FFAG permanent-magnet quadrupoles. This initial Fractional Arc Test will conclude on May 18, when the installation of the remaining seven splitter/combiner lines and the return loop will begin. CBETA operations are scheduled to begin in early 2019.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF020

Measurement of Transverse Impedance of Specific Components in CESR Using BPM Measurements of Pinged Bunches

impedance, undulator, experiment, betatron

2990

M.P. Ehrlichman, J.P. Shanks, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

A beam-based technique is applied to determine the quadrupole impedance of large-impedance components of the CESR storage ring. Two bunches separated by ~1/3 of the ring circumference are charged to 0.85 and 0.3 mA. Each bunch is given a single kick, either horizontal or vertical. Turn-by-turn, bunch-by-bunch position information is recorded for ~16 k turns. BPM-by-BPM phase is calculated using the All-phase FFT method of spectral analysis. The difference in the BPM-to-BPM phase advance between the two bunches is a measurement of the local transverse impedance. The impedances of the small-aperture in-vacuum undulators, collimators, scrapers, RF cavities, electrostatic separators, and bulk impedance of the remaining ring are determined in this manner.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF020

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF022

Beam Breakup Studies for the 4-Pass Cornell-Brookhaven Energy Recovery Linac Test Accelertor

HOM, simulation, lattice, dipole

2996

W. Lou, G.H. Hoffstaetter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Cornell University and Brookhaven National Laboratory are currently designing the Cornell-BNL ERL-FFAG Test Accelerator (CBETA). To be built at Cornell Wilson Lab, CBETA utilizes the existing ERL injector and main linac cryomodule (MLC). As the electron bunches pass through the MLC cavities, higher order modes (HOMs) fields are excited. The recirculating bunches interact with the HOMs, which can give rise to beam-breakup instability (BBU). We would present simulation results on how BBU limits the maximum achievable current, and potential ways to improve the threshold current.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF022

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF039

IP Orbit Correction Update for HL-LHC

alignment, quadrupole, optics, dipole

3048

D. Gamba, R. De Maria
CERN, Geneva, Switzerland

Funding: Research supported by the HL-LHC project.
The HL-LHC design foresees a substantial modification of the LHC layout next to the low beta Interaction Points (IPs), namely IP1 and IP5. The inner triplets will be replaced by larger aperture ones to achieve lower beta at the IPs and crab cavities (CCs) will be installed. This will add new constraints to the orbit control, which required a careful choice of location and strength of the new orbit correctors to be installed in the area. The new orbit correction system will need to correct for the unavoidable imperfections, but also provide the necessary flexibility for implementing and optimising the crossing scheme. Detailed studies of the HL-LHC layout versions HLLHCV1.0 and HLLHCV1.1 were already performed. This paper is the continuation of these works and is based on the latest layout HLLHCV1.3. A simplification of the previous analysis is proposed that helps to identify the dominant imperfections. The expected performance and tolerances of the present layout are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF041

Uncontrolled Longitudinal Emittance Blow-Up during RF Manipulations in the CERN PS

impedance, emittance, simulation, controls

3056

A. Lasheen, H. Damerau, G. Favia
CERN, Geneva, Switzerland

The CERN Proton Synchrotron (PS) determines the basic bunch spacing for the Large Hadron Collider (LHC) by means of rf manipulations. Several rf systems in a frequency range from 2.8 MHz to 200 MHz are available for beam acceleration and manipulations. Each of the six bunches injected from the PS Booster is split in several steps into 12 bunches spaced by 25 ns, yielding a batch of 72 bunches at transfer to the Super Proton Synchrotron (SPS). In the framework of the LHC Injector Upgrade (LIU) project the bunch intensity must be doubled. However, with most of the planned upgrades already in place this intensity has not yet been achieved due to collective effects. One of them is uncontrolled longitudinal emittance blow-up during the bunch splittings. In this contribution, measurements of the blow-up during the splitting process are presented and compared with particle simulations using the present PS impedance model. Beam-based measurements of the impedances of the rf cavities have been performed. They revealed that to reproduce the instability an additional impedance source is required in the PS impedance model.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF041

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF042

Improvement of the Longitudinal Beam Transfer from PS to SPS at CERN

acceleration, emittance, controls, proton

3060

A. Lasheen, H. Damerau, J. Repond, M. Schwarz, E.N. Shaposhnikova
CERN, Geneva, Switzerland

The beam transfer from the Proton Synchrotron (PS) to the Super Proton Synchrotron (SPS) at CERN is a critical process for the production of beams for the Large Hadron Collider (LHC). A bunch-to-bucket transfer is performed with the main drawback that the rf frequency in the SPS (200 MHz) is five times higher than the one in the PS (40 MHz). The PS bunches are therefore shortened non-adiabatically before extraction by applying a fast rf voltage increase (bunch rotation) to fit them into the short rf buckets in the SPS. However, particles with large amplitude of synchrotron oscillations in the PS longitudinal phase space are not properly captured in the SPS. They contribute to losses at the injection plateau and at the start of acceleration in the SPS. In this contribution, we present measurements and simulations performed to identify the source of the uncaptured particles. The tails of the particle distribution were characterized by applying longitudinal shaving during acceleration. Furthermore, the rotated bunch distribution was improved by linearizing the rf voltage using a higher-harmonic rf cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF053

Lower-Harmonic RF System in the CERN SPS

emittance, impedance, simulation, proton

3087

J. Repond, H. Damerau, A. Lasheen, E.N. Shaposhnikova
CERN, Geneva, Switzerland

Significant beam losses increasing with intensity are observed at capture and along the SPS flat bottom for the LHC-type proton beam. The intensity should be doubled for HL-LHC and high losses may be a major performance limitation. Bunches extracted from the PS, the SPS injector, are produced in a 40 MHz RF system applying a bunch rotation at the end of the cycle and therefore cannot be perfectly matched to the 200 MHz SPS RF bucket. The possibility of using a lower harmonic additional RF capture system in the SPS was already proposed after the LEP era in preparation for transfer of the LHC beam but the bunch rotation was the preferred solution, since the induced voltage in the SPS 200 MHz RF system would be too large to ensure stability in a low harmonic system without mitigation measures. However, the use of the upgraded one-turn feedback and the 200 MHz RF system as a Landau cavity could help to improve stability. The feasibility of this scenario to reduce capture losses in the SPS is analysed and presented in this paper. The choice of an optimum RF frequency and voltage is also discussed. The transfer to the main 200 MHz is simulated using a realistic bunch distribution.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF053

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF063

Identification of Imperfections in Impedance Shields on the SPS-QF Flanges via Non-Intrusive Measurements

resonance, impedance, shielding, coupling

3119

A. Farricker, P. Kramer, B.K. Popovic, E. Sunar, C. Vollinger, M. Wendt
CERN, Geneva, Switzerland

In order to achieve the highest beam intensities possible in the LHC the highest quality beam possible has to be supplied by the injector chain. The Super Proton Synchrotron (SPS) at CERN is the last accelerator in the injector chain of the LHC. One factor that is currently known to limit the intensity of the beam for injection to the LHC, is the longitudinal beam-coupling impedance in the SPS. One known source of multi-bunch instability is the vacuum flanges and campaigns to mechanically shield this source were completed in the year 2000. However, today it cannot be excluded that some of these shields may have partial or indeed full failures. Since these flanges are next to a QF magnet and are in most cases connected to a BPH (Beam Position Monitor Horizontal), it is possible to carry out via the BPH an in-situ measurement of the effectiveness of the shields. In this paper we present a methodology as well as measurement results taken with this non-intrusive in-situ method. From measurements, it is possible to identify if the flanges are without any impedance shield, equipped with either a fully functioning shield or a shield exhibiting non-ideal properties.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF063

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF065

Semi-Empirical Hamiltonian Model for Elliptical Cavities

linac, simulation, linear-dynamics, proton

3127

E. Laface, J. F. Esteban Müller
ESS, Lund, Sweden

We propose to use the sum of TM_0m0 modes to treat a radio-frequency superconducting elliptical cavity as a pill-box cavity with variable radius. The amplitudes of the different modes are obtained interpolating the field-map of the cavity with the model. Once the field is calculated, the Hamiltonian of the cavity is constructed and used to evaluate the transfer matrices associated to each step of the field-map. The multi-particle non-linear dynamics can also be evaluated using the Lie Transform of the Hamiltonian. The results are benchmarked against the ESS Linac Simulator contained in the OpenXAL suite.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF065

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF083

LINAC-Multitool - an Open Source Java-Toolkit

linac, GUI, MMI, simulation

3179

M. Schwarz, D. Bade, J. Corbet, H. Podlech
IAP, Frankfurt am Main, Germany

Funding: Work supported by BMBF contr. No. 05P15RFRBA and HIC for FAIR.
Dedicating more precious time to advanced research instead of spending it towards time-consuming routine tasks is a desirable goal in particle accelerator simulation and development. Requirements engineering was started at IAP in order to identify routine processes at our institute's R&D that can be automated or simplified. Results indicated that there were several areas to consider: Bead pull measurements, data processing and visualization for the beam dynamics code LORASR, CST field map processing for the use with TraceWin, conversion between different particle distribution data formats and more. Subsequently development of the LINAC-Multitool started to rationalize these processes and replace preexisting scripts also to ensure consistency of results and increase transparency and reliability of computation. In order to guarantee maintainability, expandability and platform independence, LINAC-Multitool is programmed using Java and will be open source. This contribution presents the current state of development.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF083

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF084

Impact of RF Coupler Kicks on Beam Dynamics in BESSY VSR

simulation, kicker, SRF, lattice

3182

T. Mertens
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
T. Atkinson, F. Glöckner, A. Jankowiak, M. Ries, A.V. Tsakanian
HZB, Berlin, Germany

The expected BESSY II upgrade to BESSY VSR requires the installation of a superconducting RF system, consisting of four cavities. Two cavities will operate at 1.5 GHz and two at 1.75 GHz. Each of them is equipped with a Fundamental Power Coupler and with Higher Order Mode (HOM) damping waveguide couplers. Dedicated simulations of these cavities and couplers have shown that at the location of the FPC the beam will see a transverse kick [*], perturbing the closed orbit and affecting transverse beam dynamics. We present the results of simulations and experiments of the impact on transverse beam dynamics of these coupler induced kicks for different FPC orientations.
[*] Study on RF Coupler Kicks of SRF Cavities in the BESSY VSR Module
A. Tsakanian#, H.-W. Glock, T. Mertens, M. Ries, A. Velez, J. Knobloch
IPAC18

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF084

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF085

Estimation of Dielectric Losses in the Bessy VSR Warm Beam Pipe Absorbers

HOM, GUI, storage-ring, wakefield

3185

T. Flisgen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
H.-W. Glock
HZB, Berlin, Germany
A.V. Tsakanian
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany

Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association.
Currently Helmholtz Zentrum Berlin prepares the update of the BESSY II ring to BESSY VSR. The updated ring will be capable to simultaneously store short and long bunches to satisfy the various user demands. For this sake, a cryomodule accommodating two 1.5 GHz and two 1.75 GHz superconducting cavities will be installed into the storage ring. The cavity string will be equipped with warm dielectric absorber rings at both ends. Together with the waveguide dampers of the cavities, these rings damp electromagnetic fields excited by the beam. This contribution presents the estimation of the dielectric losses in the beam pipe absorber rings of the BESSY VSR module. The presented approach is based on determining a broad band impedance of the dielectric ring by exciting the numerical model with a single broad band Gaussian bunch. Subsequently, the power deposited into the ring is estimated in frequency domain by multiplying the impedance with the square of the beam current for all considered harmonics of the beam. Finally, these power contributions are added up. In addition to details of the scheme, the contribution presents results for the recent absorber layout of the BESSY VSR string.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF085

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAF087

Multi-Objective Optimization of an SRF Photoinjector with Booster Section for High Brightness Beam Performance

booster, emittance, brightness, gun

3193

E. Panofski, A. Jankowiak, T. Kamps, A. Neumann
HZB, Berlin, Germany

Several future accelerator projects, light sources and user experiments require high brightness electron beams. SRF photoinjectors operating in continuous-wave (cw) mode hold the potential to serve as an electron source generating beams of high average brightness and short bunch lengths. Different operation and design parameters of the SRF photoinjector impact the beam dynamics and thus the beam brightness. A universal multi-objective optimization program based on a genetic algorithm was developed to extract optimum gun parameter settings from Pareto-optimum solutions. After getting the first optimum results, the photoinjector is supplemented with a booster section downstream. The new optimization results are presented. Further, the optimization program is applied to evaluate the impact of the field flatness of the gun cavity on the high brightness performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF087

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK005

Measuring the Coupling Impedance of Vacuum Components for the Advanced Photon Source Upgrade Using a Goubau Line

impedance, simulation, vacuum, coupling

3211

M.P. Sangroula
IIT, Chicago, Illinois, USA
R.M. Lill, R.R. Lindberg, R.B. Zabel
ANL, Argonne, Illinois, USA

The Planned upgrade of the Advanced Photon Source to a multi-bend achromat (MBA) will increase the x-ray brightness by two to three orders of magnitude. Storing such an intense beam stably inside the narrow gap vacuum chambers requires sophisticated and appropriately designed rf-components that helps to minimize rf heating and collective instabilities associated with the impedance of these small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. In this paper, we briefly introduce the novel Goubau line (G-line) test fixture for the impedance measurement, at first, and then present our measurements data along with simulations with simulations for various vacuum components designed for the APS Upgrade.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK005

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK016

Measurement and Analysis of Synchrotron Tune Variation with Beam Current in BEPCII

synchrotron, positron, electron, impedance

3237

N. Wang, Z. Duan, G. Xu, H.S. Xu, C.H. Yu, Y. Zhang
IHEP, Beijing, People's Republic of China

Coherent synchrotron frequency shift is observed during machine studies in BEPCII (Beijing Electron Positron Collider Upgrade). The results show that the synchrotron frequency varies parabolically with the increase of the beam current. This phenomenon is supposed to be induced by the interaction of the beam with the fundamental mode of the accelerating cavity. In order to explain this phenomenon, a simple physical model is developed from the couple bunch instability theory. The analytical estimations based on the physical model show good agreement with the measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK016

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK017

Higher Order Modes in China-ADS Demo Linac

dipole, HOM, linac, higher-order-mode

3240

C. Zhang, Y. He, T.C. Jiang, R.X. Wang, S.H. Zhang
IMP/CAS, Lanzhou, People's Republic of China

Funding: Work supported by Natural Science Foundation of China，No.11505253
The study of higher order modes excited in the China-ADS Linac has been presented in this paper. The effects of the cryogenic losses and the influence on beam of the higher order modes have been investigated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK017

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK018

Recent Developments in DEMIRCI for RFQ Design

rfq, software, simulation, multipole

3243

E. Celebi
IBU, Istanbul, Turkey
O. Cakir, G. Turemen
Ankara University, Faculty of Sciences, Ankara, Turkey
G. Turemen
TAEK, Ankara, Turkey
G. Unel
UCI, Irvine, California, USA

Funding: This project has been supported by TUBITAK with project number 114F10⁶ and 117F143.
DEMIRCI software aims to aid RFQ design efforts by making the process easy, fast and accurate. In this report, DEMIRCI 8-term potential results are compared with the results provided by other commercially available simulation software. Computed electric fields are compared to the re- sults from simulations of a recently produced 352 MHz RFQ. Recent developments like the inclusion of space charge ef- fects in DEMIRCI beam dynamics are also discussed. More- over, further terms are added to 8-term potential to simulate possible vane production errors. The FEM solver was also improved to mesh the cells with errors.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK018

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK028

Beam Dynamics Simulations in the Dubna SC202 Superconducting Cyclotron for Hadron Therapy

extraction, cyclotron, proton, simulation

3270

O. Karamyshev, G.A. Karamysheva, D.V. Popov, G. Shirkov, S.G. Shirkov
JINR, Dubna, Moscow Region, Russia
V. Malinin
JINR/DLNP, Dubna, Moscow region, Russia

In 2015 the joint project JINR (Dubna, Russia) - ASIPP (Hefei, China) on design and construction of supercon-ducting proton cyclotron SC202 was started. Two cyclo-trons are planned to be manufactured in China, according to the Collaboration Agreement between JINR and ASIPP. The first cyclotron will be used for proton therapy in Hefei and the second one will replace the Phasotron in the research and treatment program on proton therapy in Dubna. New schema of extraction system and results of beam acceleration and extraction simulations for Dubna cyclotron are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK028

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK031

Suppression of Longitudinal Coupled Bunch Instability by Harmonic Cavity in UVSOR Electron Storage Ring

damping, synchrotron, storage-ring, HOM

3280

A. Mochihashi
KIT, Eggenstein-Leopoldshafen, Germany
M. Fujimoto, K. Hayashi, M. Katoh
UVSOR, Okazaki, Japan
J. H. Hasegawa, M. Hosaka, M. Hosaka, Y. Takashima, Y. Takashima
Nagoya University, Nagoya, Japan
M. Hosaka, Y. Takashima
Aichi Synchrotron Radiation Center, Aichi, Japan
M. Katoh
Sokendai - Okazaki, Okazaki, Aichi, Japan

In the UVSOR electron storage ring, which is dedicated for a VUV synchrotron radiation light source, a longitudinal coupled bunch instability (LCBI) is observed in multi-bunch operation. To suppress the LCBI, we routinely operate a third harmonic cavity (HCV) in a passive mode. By properly tuning HCV, the instability is almost completely suppressed. Because of the lower beam energy (750 MeV) and brilliant beam emittance (17.5 nm-rad), the Touschek effect becomes severe in the UVSOR. To guarantee enough beam lifetime, we also apply HCV for lengthening the bunch. The suppression of the instability and increasing the beam lifetime are crucial benefits by HCV for the UVSOR. However, not only the origin of the LCBI but also the Landau damping effect by HCV has not been understood systematically yet. We have noticed that one of the HOMs at HCV itself could cause the LCBI and observed the behavior of the instability, which strongly depends on the beam current. From the experiment we have discussed the cause of the instability with the HOM theory. We have also tried to observe synchrotron tune spread and discussed a competition between the Landau damping and the instability growth.
Present affiliation of the first auther : Karlsruhe Institute of Technology

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK031

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK037

Beam-Loading Transients and Bunch Shape in the Operation of Passive Harmonic Cavities in the ALS-U

simulation, beam-loading, impedance, controls

3298

Z. Pan, S. De Santis, C. Steier, C. Sun, M. Venturini
LBNL, Berkeley, USA
T. Hellert
DESY, Hamburg, Germany
C.-X. Tang
TUB, Beijing, People's Republic of China

The ALS-U is a major upgrade of the LBNL ALS to a diffraction limited light source. The current plan is to replace all the vacuum and magnet components while retaining the existing 500 MHz main and third-harmonic, passively operated, rf cavities, but replacement of the existing rf cavities is also being considered. A new feature, is represented by beam-loading transients associated with a beam consisting of 11 bunch trains separated by 10 ns gaps as needed to enable on-axis swap-out injection. In this paper we study these transients and the associated bunch-to-bunch phase, length, and profile variations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK037

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK062

Bunch Compression of Flat Beams

emittance, simulation, experiment, booster

3368

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
D.J. Crawford, D.R. Edstrom, D. Mihalcea, S. Nagaitsev, P. Piot, A.L. Romanov, J. Ruan, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

Funding: This work is supported by the DOE contract No.DEAC02-07CH11359 to the Fermi Research Alliance LLC. A.H. is supported by the DOE under contract No. DE-SC0011831 with Northern Illinois University.
Flat beams can be produced via a linear manipulation of canonical angular momentum (CAM) dominated beams using a set of skew-quadrupole magnets. Recently such beams were produced at Fermilab Accelerator Science and Technology (FAST) facility. In this paper, we report the results of flat beam compression study in a magnetic chicane at an energy of E~32 MeV. Additionally, we investigate the effect of energy chirp in the round-to-flat beam transform. The experimental results are compared with numerical simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK062

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK069

Open XAL Status Report 2018

linac, MMI, diagnostics, GUI

3388

A.P. Zhukov, C.K. Allen, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA
C.P. Chu, Y. Li
IHEP, Beijing, People's Republic of China
J.F. Esteban Müller, E. Laface, Y. Levinsen, N. Milas, C. Rosati
ESS, Lund, Sweden
P. Gillette, G. Normand, A. Savalle
GANIL, Caen, France
X.H. Lu
CSNS, Guangdong Province, People's Republic of China

The Open XAL accelerator physics software platform is being developed through an international collaboration among several facilities since 2010. The goal of the collaboration is to establish Open XAL as a multi-purpose software platform supporting a broad range of tool and application development in accelerator physics and high-level control (Open XAL also ships with a suite of general purpose accelerator applications). This paper discusses progress in beam dynamics simulation, new RF models, and updated application framework along with new generic accelerator physics applications. We present the current status of the project, a roadmap for continued development and an overview of the project status at each participating facility.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK069

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK070

Coupled Bunch Instability from JLEIC Crab Cavity Higher Order Modes

HOM, impedance, luminosity, feedback

3392

S.I. Sosa Guitron, S.U. De Silva, J.R. Delayen, H. Park
ODU, Norfolk, Virginia, USA
R. Li, V.S. Morozov, H. Park
JLab, Newport News, Virginia, USA

Particle bunches traveling in a ring can excite wakefields inside any radio-frequency element present. These electromagnetic modes can resonate long enough and interact with subsequent passing bunches. A coherent oscillation between bunches can quickly become an instability and needs to be addressed. The Jefferson Lab electron ion collider has a large 50 mrad crossing angle and thus relies on bunch crabbing to achieve high luminosity. Bunch crabbing is done with compact superconducting rf dipole cavities. We study coupled bunch oscillations driven by the higher order modes of multicell RFD crab cavities under study for JLEIC, we calculate the instability growth time assuming a symmetric beam spectrum, identify the HOMs driving the instability and discuss mitigation measures.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK070

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK077

Feasibility of Non-Metal Vacuum Chamber for Storage Rings

impedance, vacuum, insertion-device, insertion

3411

T.-Y. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

This paper studies if the vacuum chamber of an elec-tron storage ring can be made of dielectric non-meta materials such as ceramics or glass. The purpose of this study is to substantially reduce the broadband imped-ance of the vacuum chamber and consequently mitigate single bunch instabilities. This theoretical study examines how these materials can reduce the impedance and pro-poses how to resolve technical problems to occur.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK077

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK105

Construction Progress of Two Superconducting Cyclotrons for Proton Therapy and Proton Irradiation at CIAE

cyclotron, proton, extraction, controls

3477

T.J. Zhang, S. An, H.R. Cai, L.C. Cao, X.L. Cao, T. Cui, X.L. Fu, T. Ge, P.F. Gong, F.P. Guan, L.L. Guan, S.G. Hou, B. Ji, X.L. Jia, M. Li, X.L. Li, Y.Q. Li, J. Lin, J.Y. Liu, X.T. Lu, Y.L. Lv, C. Wang, F. Wang, F. Wang, L. Wang, J.Y. Wei, S.M. Wei, J.S. Xing, G. Yang, J.J. Yang, M. Yin, Z.G. Yin, D.S. Zhang, S.P. Zhang, X. Zhen
CIAE, Beijing, People's Republic of China
K. Fong
TRIUMF, Vancouver, Canada

Funding: Supported partly by the National Natural Science Foundation of China (Grant No. 11375273 and 11475269) and by the Ministry of Science and Technology under Grant 2016YFC0105300.
There are very strong demand for mid-energy of proton machine recent years due to the surging cancer patients and fast progress of the space science in China. For the applications of proton therapy and proton irradiation, the energy range of proton beam usually is from 200 MeV to 250 MeV, or even higher for astronavigation. Based on the R&D starting from 2009, two construction projects of 230 MeV and 250 MeV superconducting cyclotron, which have been implemented recently at China Institute of Atomic Energy(CIAE). That was started in Jan 2015 for the 230 MeV machine, for the program of proton therapy and space science launched by China National Nuclear Corporation (CNNC), and in Jan 2016 for the 250 MeV machine, for the program of proton therapy launched by the Ministry of Science and Technology of China (MOST). In this paper, the designs for the two SC cyclotrons and their key components, including the main magnet, SC coils, RF system, internal ion source and central region, extraction system, etc, and the construction progress of the machines will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK105

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK113

Cavity Characterization Studies With the Latest Revision of YACS

storage-ring, coupling, superconducting-cavity, higher-order-mode

3503

B.D. Isbarn, S. Koetter, B. Riemann, M. Sommer, T. Weis
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF under contract no. 05K13PEB.
YACS is a 2.5D finite element method solver capable of solving for the full 3D eigenfrequency spectra of resonant axisymmetric structures while reducing the computational problem to a 2D rotation plane. The most recent revision of YACS now supports arbitrary order basis functions for the geometry and field discretization. In earlier revisions of YACS spurious modes were introduced by increasing the order of either the geometry or field basis functions. To prevent the emergence of spurious modes, YACS now matches the function spaces of the in-plane and out-plane function basis, and thus yields spurious free solutions. To demonstrate the capabilities of YACS, extensive cavity characterization studies on curved multicell microwave cavities are presented. Due to the combined utilization of the rotation symmetry, higher order basis functions and curved elements, eigenfrequency spectra above 10 GHz for L-band multicell structures can be easily obtained.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK113

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK115

Numerical Multiparticle Tracking Studies on Coupled-Bunch Instabilities in the Presence of RF Phase Modulation

wakefield, impedance, synchrotron, damping

3511

M. Sommer, B.D. Isbarn, S. Koetter, B. Riemann, T. Weis
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF under contract no. 05K13PEB.
Since 2008, longitudinal coupled-bunch instabilities are suppressed at DELTA by a modulation of the phase of the accelerating RF field inside the cavity. To achieve a deeper understanding of the interaction of both effects, experimental studies have been made in 2016. These studies show a quadratic dependency of the coupled-bunch mode damping rates on the phase modulation amplitude. Recently, a numerical particle tracking code has been developed to confirm the experimental results. It is based on long range wake field effects produced inside an RF cavity acting on multi particle bunches of arbitrary charge, together with phase focusing by a phase modulated accelerating field. The numerical results confirm the quadratic dependency of damping rates on the phase shift obtained in experimental studies before.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK115

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK118

Beam Dynamics Studies for a Strong-Focusing Cyclotron

dipole, focusing, cyclotron, betatron

3522

J. Gerity, S. Assadi, P.M. McIntyre, A. Sattarov
Texas A&M University, College Station, USA

Results are presented from end-to-end simulation of a 100 MeV strong focusing cyclotron (SFC). The develop-ment of the high-current SFC is motivated by applica-tions for production of medical isotopes and for a proton driver for subcritical fission. It uses a novel superconducting cavity to provide suffi-cient energy gain to fully separate all turns. An arc-contour F-D doublet, trim dipole winding, and sextupole are located along each turn within the aperture of each sector dipole to control the betatron and synchrotron motion and to stabilize non-linear dynamics with high-current operation. The phase space evolution of a proton bunch in the SFC was simulated using both the code OPAL and an ad hoc Runge-Kutta tracker. Iterative optimization of the dipole, quadrupole, and sextupole fields was used to provide precise isochronicity, favorable betatron phase advance, and cancellation of dispersion in each cell.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK118

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK122

Longitudinal Coupled Bunch Instability in JLEIC

HOM, impedance, electron, resonance

3530

R. Li, J. Guo, F. Marhauser, S. Wang
JLab, Newport News, Virginia, USA

Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The luminosity performance of the JLEIC design is achieved by using a high bunch repetition rate (476MHz) with moderate bunch charges, similar to the strategy employed in modern lepton colliders. Such a bunch configuration will make single bunch instabilities less probable, yet makes the machine more prone to the onset of longitudinal and transverse coupled bunch instabilities. Consequently, this will set higher demands on the bunch-by-bunch feedback systems to mitigate the multi-bunch instabilities. In this paper we present our detailed analysis of the growth rate of the coupled bunch instabilities for beams in both the electron and ion rings in JLEIC at the collision scenario. The implication of the growth rate on the feedback system will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK122

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK123

Updates on Collective Effects Estimations for JLEIC

electron, impedance, collider, luminosity

3533

R. Li, K. E. Deitrick, T.J. Michalski
JLab, Newport News, Virginia, USA

Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
JLEIC is the high luminosity and high polarization electron-ion collider (EIC) currently under active design at Jefferson Lab. It aims at high luminosity (10³³~10³⁴ cm^-2s⁻¹) for a wide range of ion species and center-of-mass energies. This luminosity performance relies sensibly on beam stability with high intensity electron and ion beam operation. The impedance budget analysis and the estimations of the single and multibunch instabilities are currently underway. In this paper, we present the update status of estimations for the longitudinal and transverse coherent instabilities, and identify areas or parameter regimes where special attentions for instability mitigations are required.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK123

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAK131

Investigation of Two-Bunch Train Compression by Velocity Bunching

bunching, electron, emittance, experiment

3548

D. Wang, Y. C. Du, W.-H. Huang, X. Liu, X.L. Su, C.-X. Tang, Q.L. Tian, L.X. Yan
TUB, Beijing, People's Republic of China
H. Zhang
Tsinghua University, Beijing, People's Republic of China

Two electron beamlets, also referred as two-bunch train with adjustable time and energy spacing are popular in many applications such as two color FEL and pump-probe experiments. We investigate compression of two-bunch train via velocity bunching scheme in a traveling wave accelerator (TWA) tube by varying the phase of TWA tube in a very large range. Beam dynamics simulations show that when the phase injected into the accelerator tube for the beam is set to ≪-100 degree, velocity bunching occurs in a deep over-compression mode, where two-bunch train is continuously tunable in time and in energy space, and the emittance of each sub-bunch is also preserved. In the experiment, we use energy spectrum and defecting cavity to diagnose the train's energy space and time space respectively, the measurements demonstrated that two-bunch train through deep over-compression scheme is separated both in time and in energy space, which also agree well with the predictions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK131

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL002

RF System Operation of High Current RFQ in ADS Project

rfq, operation, coupling, LLRF

3613

L.P. Sun, R. Huang, C.X. Li, L. Lu, A. Shi, L.B. Shi, W.B. Wang, X.B. Xu, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China
Y. Hu
TUB, Beijing, People's Republic of China

Funding: Work supported by Natural Science Foundation of China， No.11505253
New RF system has been upgraded several times for high-current operation, especially for extra beam power and detuning angle. The current was increased gradually resulting in more and more frequency detuning, and an effective method is to tune the temperature of cavity to compromise detuning. Of course, the power dissipated in cavity and high intensity beam are approximately 120kW resulting in too many power modules operated in the high risk of failure. The specific analysis and simulation were introduced in detail.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL002

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL004

Research and Development of RF System for SC200 Cyclotron

LLRF, cyclotron, simulation, acceleration

3616

G. Chen, C. Chao, G. Liu, X.Y. Long, Z. Peng, Y. Song, Y.S. Wang, C.S. Wei, M. Xu, Q. Yang, X. Zhang, Y. Zhao
ASIPP, Hefei, People's Republic of China
L. Calabretta, A.C. Caruso
INFN/LNS, Catania, Italy
O. Karamyshev, G.A. Karamysheva, N.A. Morozov, E. Samsonov, G. Shirkov
JINR, Dubna, Moscow Region, Russia

A 200MeV compact isochronous superconducting cyclotron, named SC200, for proton therapy is under development by collaboration of ASIPP (Hefei, China) and JINR (Dubna, Russia). The radio frequency (RF) system as one of most significant subsystems in cyclotron consists of acceleration cavity, low level RF, RF source and transmission network. SC200 has two cavities connected in the centre, which are operated at 91.5 MHz with second harmonic. To meet the required acceleration voltage, the cavities have been carefully designed with comprised choices between several aspects, such as Q factor, mechanic stability and so on. The low-level RF (LLRF) system has been implemented by using the FPGA to achieve the significant accelerating voltage with an amplitude stability of <0.2% and a phase stability of < 0.1 degree. The cavity and LLRF system have been tested outside of cyclotron, the results will be presented. For future, the commissioning of whole RF system will be started after the assembly of SC200 at the end of 2019.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL004

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL007

Upgrade of PIAVE Superconducting RFQs at INFN-Legnaro

rfq, SRF, operation, superconducting-RF

3623

G. Bisoffi, E. Bissiato, D. Bortolato, F. Chiurlotto, T. Contran, E. Fagotti, A. Minarello, P. Modanese, E. Munaron, D. Scarpa
INFN/LNL, Legnaro (PD), Italy
V. Andreev
ITEP, Moscow, Russia
A. Bosotti, R. Paparella
INFN/LASA, Segrate (MI), Italy
L.M.A. Ferreira
CERN, Geneva, Switzerland
K. Kasprzak
IFJ-PAN, Kraków, Poland
R.C. Pardo
ANL, Argonne, Illinois, USA

Superconducting RFQs (SRFQs), the first SC RFQs ever made operational for users, have been operated on the PIAVE SC heavy ion linac injector at INFN-Legnaro since 2006. The structure is split into two resonators and is limited to the accelerating RFQ sections. The resonators had never exceeded 80% of the design accelerating fields. In 2015, an upgrade plan started, aimed at increasing the accelerating fields, while improving their slow and fast tuning systems, repairing degraded components, imple-menting a LASER alignment method. The upgrade plan was successfully concluded in summer 2017. The resona-tors were kept stably locked for days at a field larger than the nominal one. Eventually, a test beam was accelerated successfully for 72 hours, with negligible locking issues. SRFQs entered once again routine operation in December 2017. The new features will allow to accelerate heavy ions with an A/q value as high as 8.5 (versus a former maximum A/q=7.5), allowing operation of the very first accelerated uranium beams at INFN-LNL, after the relat-ed authorizations shall have been issued.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL007

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL012

Soft Chemical Polishing and Surface Analysis of Niobium Samples

niobium, SRF, linac, operation

3641

J. Conrad, L. Alff, M. Arnold, S. Flege, R. Grewe, M. Major, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany

Funding: Work supported by the German Federal Ministry for Education and Research (BMBF) under Grant No. 05H15RDRBA
The Superconducting Darmstadt Linear Accelerator S-DALINAC uses twelve Niobium Cavities with a RRR of 280 which are operated at 2 K. The operating frequency is 3 GHz; the design value of the accelerating gradient is 5 MV/m. To achieve the target value of 3 x 10˄9 for Q0, different surface preparation methods were applied and systematically tested using a vertical 2 K cryostat. A well-established technique is the so called Darmstadt Soft Chemical Polishing, which consists of an ultrasonic cleaning of the cavity with ultrapure water followed by oxidizing the inner surface with nitric acid. After rinsing with water the niobium oxide layer is removed with hydrofluoric acid in a separate second step. Finally the structure is rinsed and then dried by a nitrogen flow. Until now each cavity in operation was chemically treated with a proven record of success. In order to understand and to optimize the process on the niobium surface, systematic tests with samples were performed and analyzed using material science techniques like SEM, SIMS and EDX. We will report on the results of our research and we will give a review on our experiences with varied chemical procedures.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL012

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL015

Evaluation of superconducting characteristics on the thin-film structure by NbN and Insulator coatings on pure Nb substrate

embedded, SRF, radio-frequency, electromagnetic-fields

3653

R. Katayama, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
C.Z. Antoine
CEA/IRFU, Gif-sur-Yvette, France
A. Four
CEA/DRF/IRFU, Gif-sur-Yvette, France
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
R. Ito, T. Nagata
ULVAC, Inc, Chiba, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

Funding: The work is supported by JSPS KAKENHI Grant Numbers JP17H04839, JP26600142 and the Collaborative Research Program of ICR Kyoto University (grant 2016-8, 2017-8, 2017-9).
In recent years, it is pointed out that the maximum accelerating gradient of a superconducting RF cavity can be pushed up by coating the inner surface of cavity with a multilayer thin-film structure that consists of alternate insulator and superconductive layers. In this structure, the principal parameter that limits the performance of the cavity is the critical magnetic field or effective Hc1 at which vortices start penetrate into the first superconductor layer. We made a sample that has NbN/SiO2 thin-film structure on pure Nb substrate by DC magnetron sputtering method. In this paper, we will report the measurement results of effective Hc1 of the sample by the third-harmonic voltage method.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL018

DQW HOM Coupler Design for the HL-LHC

HOM, impedance, simulation, GUI

3663

J.A. Mitchell
Lancaster University, Lancaster, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
R. Calaga
CERN, Geneva, Switzerland
S. Verdú-Andrés, B. P. Xiao
BNL, Upton, Long Island, New York, USA

HOMs in the DQW crab cavity can produce large heat loads and beam instabilities as a result of the high current HL-LHC beams. The DQW crab cavity has on-cavity, coaxial HOM couplers to damp the HOMs whilst providing a stop-band response to the fundamental mode. Manufacturing experience and further simulations give rise to a set of desirable coupler improvements. This paper will assess the performance of the current HOM coupler design, present operational improvements and propose an evolved design for HL-LHC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL018

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL025

New Drift-Tube Linac RF Systems at LANSCE

DTL, controls, LLRF, detector

3680

J.T.M. Lyles, R.E. Bratton, M.S. Prokop, D. Rees
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
LANSCE has restored the proton drift-tube linac (DTL) to high-power capability after the original RF-power tube manufacturer could no longer supply devices that consistently met our high-average power requirement. Thales TH628L Diacrodes® now supply RF power to three of the four DTL tanks. These tetrodes reused the existing infrastructure including water-cooling systems, coaxial transmission lines, high-voltage power supplies and capacitor banks. Each transmitter uses a combined pair of power amplifiers to produce up to 3- MW peak and 360- kW of mean power. A new intermediate power amplifier was simultaneously developed using a TH781 tetrode. Design and prototype testing of the high-power stages was completed in 2012, with commercialization following in 2013. Each installation was accomplished during a 4 to 5 month beam outage each year from 2014-2016. A new digital low-level RF control system was designed, built and placed into operation in 2016. The interaction of the dual power amplifiers, the I/Q LLRF, and the DTL cavities provided many challenges that were overcome. The replacement RF systems have completely met our accelerator requirements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL025

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL028

Commissioning of the Bunch-by-Bunch Feedback System in the MAX IV 1.5 GeV Ring

feedback, storage-ring, kicker, synchrotron

3688

D. Olsson, Å. Andersson, F.J. Cullinan, P.F. Tavares
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV 1.5 GeV ring is an electron storage ring for production of synchrotron light in the IR to soft X-ray spectral range. The ring will deliver light to its first users during 2018. Bunch-By-Bunch (BBB) feedback has been needed to suppress coupled-bunch mode instabilities (CBMIs), and the feedback has this far been provided in all three planes by a single stripline kicker. This is done by combining the horizontal and vertical baseband feedback signals with the longitudinal feedback signal that is upconverted to the 150 MHz - 250 MHz range. The combined signal is then fed to two stripline electrodes. The layout of the BBB feedback system in the MAX IV 1.5 GeV ring is presented in this paper. Results from instability studies are also discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL028

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL029

Comparison of Horizontal and Vertical Electropolishing Methods using Niobium Single-Cell Coupon Cavity

cathode, niobium, accumulation, experiment

3692

V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

Horizontal electropolishing (HEP) is an established tech-nique for surface treatment of niobium accelerating cavi-ties. Vertical electropolishing (VEP), in which the cavity is electropolished in the vertical posture, is in R&D phase for parameter optimization. We performed HEP and VEP of a niobium single-cell coupon cavity to compare the effect of both the methods on surface state and removal at different positions of the cavity. HEP was performed at STF, KEK with the standard EP parameters. VEP was performed at Marui Galvanizing Company with a cathode called 'Ninja cathode' that can be rotated during the VEP process. The optimized cathode design and VEP parame-ters resulted in symmetric removal as obtained with the HEP technique and yielded a smooth inner surface of the entire cavity

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL029

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL030

Vertical Electropolishing of 1.3 GHz Niobium 9-Cell Cavity: Parameter Study and Cavity Performance

cathode, accumulation, niobium, linac

3695

V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

VEP parameters and process have been already optimized with single-cell 1.3 GHz niobium cavity at Marui Galva-nizing Company working in collaboration with KEK. A unique cathode called 'Ninja cathode' with an optimized shape was applied to single-cell cavities. The cathode was effective to stop the bubble accumulation in the upper half-cell of the cavity and yielded smooth surface and uniform removal in the cell. This work shows parameter study with the Ninja cathode and a 9-cell coupon cavity which contains totally 9 coupons and viewports in the first, fifth, and ninth cells. Effects of temperature and acid flow in the cathode housing were studied using coupon currents and by observing bubbles through the viewports. The adequate parameters found with 9-cell coupon cavity were applied on a 9-cell cavity to be tested in vertical cryostat. The VEP and vertical test results are reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL031

Development of a Vertical Electropolishing Facility for Nb 9-Cell Cavity

niobium, cathode, controls, site

3699

Y.I. Ida, V. Chouhan, K.N. Nii
MGH, Hyogo-ken, Japan
akabori. Akabori, G.M. Mitoya, K. Miyano
HKK, Morioka, Japan
Y. Anetai, F. Takahashi
WING. Co.Ltd, Iwate-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

Our Nb accelerating cavity vertical electropolishing (VEP) facility development group which was led by KEK started single-cell VEP facility development from 2014. This is based on horizontal electropolishing (HEP) techniques developed by KEK over 10 years and stainless steel electropolishing techniques developed by Marui over 30 years. We have reported results of Nb cavity VEP with Ninja cathode so far. In order to achieve international linear collider (ILC) construction, it is said that cost reduction and productivity improvement are necessary, however in case of 9-cell cavity, uniform inner surface polishing is difficult, as well known to predecessors. In this article, we will present the first report of VEP facility development from initial transparent plastic mock-up to improvement for Nb 9-cell cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL031

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL032

1.3GHz Nb Single-Cell Cavity Vertical Electropolishing with Ninja Cathode and Results of Vertical Test

cathode, accelerating-gradient, experiment, factory

3702

K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
MGH, Hyogo-ken, Japan
H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

Marui Galvanizing Co., Ltd. has been developing Nb cavity vertical electropolishing (VEP) technologies in collaboration with KEK. Until now, we reported that inner surface state and removal thickness distribution were improved in VEP with Ninja cathode and coupon cavity. This time, a 1.3GHz Nb single-cell cavity VEP with Ninja cathode was performed in Marui and vertical test was performed in KEK. The inner surface state and removal thickness distribution were satisfactory. And as a result of vertical test, the accelerating gradient of 32MV/m (Q0=8.0E9) was achieved.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL034

Dynamic Tuner Development for Medium β Superconducting Elliptical Cavities

linac, operation, SRF, superconducting-RF

3709

C. Contreras-Martinez, P.N. Ostroumov
FRIB, East Lansing, USA
E. Borissov, S. Cheban, Y.M. Pischalnikov, V.P. Yakovlev, J.C. Yun
Fermilab, Batavia, Illinois, USA

Funding: Work supported by U.S. DOE SCGSR program under contract number DE-SC0014664, Michigan State University, and Fermi Research Alliance under contract N. DEAC02-07CH11959 with the U.S. DOE
The Facility for Rare Isotope Beams (FRIB) is developing a 5-cell 644 MHz β_opt=0.65 elliptical cavity for a future linac energy upgrade to 400 MeV/u for the heaviest uranium ions. Superconducting elliptical cavities operated in continuous wave, such as the ones for FRIB, are prone to microphonics which can excite mechanical modes of the cavities. It has been shown that the detuning due to microphonics can be mitigated with the use of piezo actuators (fast tuner) as opposed to the costly option of increasing the input RF power. The FRIB slow/fast dynamic tuner will be based on the Fermilab experience with similar tuners like those developed for the linac coherent light source (LCLS) II and proton improvement plan (PIP) II. This paper will present the results of tuner properties on the bench.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL035

Design of β=0.65, 5 Cells, 644 MHz Elliptical Cavity for FRIB Upgrade

linac, cryomodule, niobium, operation

3712

M. Xu, C. Compton, C. Contreras-Martinez, W. Hartung, S.H. Kim, S.J. Miller, P.N. Ostroumov, A.S. Plastun, J.T. Popielarski, L. Popielarski, M.A. Reaume, K. Saito, A. Taylor, J. Wei, T. Xu, Q. Zhao
FRIB, East Lansing, USA
I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the U.S. DOE Office of Science under Cooperative Agreement DE-SC0000661 and the NSF under Cooperative Agreement PHY-1102511, the State of Michigan and Michigan State University.
The superconducting (SC) linac of the Facility for Rare Isotope Beams (FRIB) under construction will deliver 200 MeV/u, 400 kW beam to the target for producing rare isotopes at Michigan State of University (MSU). For further beam energy upgrade, we have designed the β = 0.65, 5 cells, 644 MHz elliptical cavity. The beam energy can be upgraded to 400 MeV/u by installing 11 cryomodules to the available space in the FRIB tunnel.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL035

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL036

Nb3Sn Thin Films for the Production of Higher Gradient SRF Cavities at Reduced Cost

niobium, SRF, superconductivity, site

3716

S.A. Kahn, M.A. Cummings
Muons, Inc, Illinois, USA
E.Z. Barzi, D. Turrioni
Fermilab, Batavia, Illinois, USA
S. Falletta
Politecnico di Torino, Torino, Italy
A. Kikuchi
NIMS, Tsukuba, Ibaraki, Japan

High gradient superconducting cavities (SRF) will be needed for future accelerators. The higher gradient can achieve the high energy with fewer cavities. However the accelerating field of niobium cavities is limited by the peak magnetic field on the cavity surface. Cavities coated with Nb3Sn have a significantly larger Hc2 allowing the cavity to achieve a larger gradient. Measurements of Nb3Sn coated cavities have achieved about half the theoretical predicted gradient. It is possible to improve Nb3Sn plated cavity performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL036

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL038

Phase Grouping of Larmor Electrons by a Synchronous Wave in Controlled Magnetrons

controls, electron, operation, cathode

3723

G.M. Kazakevich, R.P. Johnson
Muons, Inc, Illinois, USA
V.A. Lebedev, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

A simplified analytical model based on the charge drift approximation has been developed. It considers the resonant interaction of the synchronous wave with the flow of Larmor electrons in a magnetron. The model predicts stable coherent generation of the tube above and below the threshold of self-excitation. This occurs if the magnetron is driven by a sufficient resonant injected signal (up to -10 dB). The model substantiates precise stability, high efficiency and low noise at the range of the magnetron power control over 10 dB by variation of the magnetron current. The model and the verifying experiments with 2.45 GHz, 1 kW magnetrons are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL038

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL039

Improved Magnetron Stability and Reduced Noise in Efficient Transmitters for Superconducting Accelerators

controls, SRF, feedback, experiment

3726

G.M. Kazakevich, R.P. Johnson
Muons, Inc, Illinois, USA
V.A. Lebedev, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

State of the art high-current superconducting accelerators require efficient RF sources with a fast dynamic phase and power control. This allows for compensation of the phase and amplitude deviations of the accelerating volt-age in the Superconducting RF (SRF) cavities caused by microphonics, etc. Efficient magnetron transmitters with fast phase and power control are attractive RF sources for this application. They are more cost effective than traditional RF sources such as klystrons, IOTs and solid-state amplifiers used with large scale accelerator projects. However, unlike traditional RF sources, controlled magnetrons operate as forced oscillators. Study of the impact of the controlling signal on magnetron stability, noise and efficiency is therefore important. This paper discusses experiments with 2.45 GHz, 1 kW tubes and verifies our analytical model which is based on the charge drift approximation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL041

Power Coupler Design for the LUCRECE Project

simulation, SRF, coupling, linac

3732

H. Guler, D. Auguste, J. Bonis, O. Bouras, M. El Khaldi, W. Kaabi, P. Lepercq
LAL, Orsay, France

The LUCRECE project aims at developing an elementary RF system (cavity, power source, LLRF and controls) suitable for continuous (CW) operation at 1.3 GHz. This effort is made in the framework of the advanced and compact FEL project LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation), using superconducting linac technology for high repetition rate and multi-user operation (www.lunex5.com). In this context, based on its large experience on coupler design and RF conditioning, LAL Laboratory is in charge of the design and the fabrication of RF couplers that could operate at up to 15-20 kW in CW mode. For this purpose, geometry based on CORNELL 65kW CW couplers will me modified to fulfil the LCLS2 type cavity with the high necessary coupling level. Electromagnetic simulations and optimisation and associated thermal heating will be discussed. Methods to decrease the thermal impact, and strategy for RF conditioning will be considered.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL041

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL042

Injection Locked 1497 MHz Magnetron

injection, superconducting-cavity, site, medical-accelerators

3736

M.L. Neubauer, A. Dudas, S.A. Kahn
Muons, Inc, Illinois, USA
R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

A novel injection-locked 1497 MHz 13 kW AM magnetron design is presented. The anode design to minimized eddy currents due to the changing magnetic field is presented. Thermal calculations of two design options are also presented. An extra degree of freedom in the anode construction is made possible by the fact that the magnetron is injection locked. This fact presents some additional design details that can be utilized in the cooling network for the magnetron anode.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL042

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL045

Determination of the Electron Bunch Length With Third Harmonic Cavity for the Taiwan Photon Source

operation, simulation, SRF, electron

3745

Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is a modern 3 GeV low emittance light source with RMS bunch lengths of about 3 mm at a beam current of 500 mA and operating gap voltage of 3.2 MV. With a higher harmonic cavity, we could increase the Touschek lifetime and lower the heat load of in-vacuum undulators by lengthening the bunch lengths. Preliminary studies show that for full and uni-form fill patterns, the bunch lengths could be increased by a factor of four. However, this calculation ignores phase transient effects and may overestimate the effect of harmonic cavities. A multi-bunch, multi-particle tracking method has been developed to determine the bunch lengths for non-uniform fill patterns, which also takes phase transient effects into account and the expected maximum bunch lengthening factor for different TPS operation conditions are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL045

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL060

Advanced Modeling of Klystrons by the Tesla-Family of Large-Signal Codes

klystron, impedance, experiment, simulation

3785

I.A. Chernyavskiy, D.K. Abe, B. Levush, A.N. Vlasov
NRL, Washington, DC, USA
T.M. Antonsen
UMD, College Park, Maryland, USA
T.M. Antonsen
Leidos Corp, Billerica, MA, USA
J. Rodgers
Naval Research Laboratory (NRL), Washington, USA

Funding: US Office of the Naval Research
Klystrons and IOTs are widely used or proposed to be used in accelerators as high-power RF sources. Development and optimization of klystron and IOT designs is aided by the use of different simulation tools, including highly efficient large-signal codes. We present an overview of the advances in the code development and modeling using Naval Research Laboratory (NRL) set of TESLA-family of large-signal codes, suitable for the modeling of single-beam and multiple beam klystrons and IOTs. Original 2D large-signal algorithm of the code TESLA* was developed for the modeling of klystrons based on (relatively) high Q resonators and is applicable to the multiple-beam devices in an approximation of identical beams/beam-tunnels. Parallel extension of TESLA algorithm (code TESLA-MB**) enabled an accurate, quasi-3D modeling of multiple-beam devices with non-identical beams/beam-tunnels. Recently developed more general TESLA-Z algorithm*** is based on the impedance matrix approach and enabled geometry-driven large-signal modeling. Examples of applications of TESLA-family of codes to the modeling of advanced single-beam and multiple-beam klystrons (and IOTs) will be presented.
*A.N. Vlasov, et al,IEEE TPS, v.30(3), 1277-1291, June 2002
**I.A. Chernyavskiy, et al.,IEEE TPS, v.36(3), 670-681, June 2008
***I.A. Chernyavskiy, et al.,IEEE TED, v.64(2), 536-542, Feb 2017

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL060

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL061

Simulation of Pulsed Temperature Rise in Cryogenic Copper RF Cavity Achieving a Very High Accelerating Field

simulation, accelerating-gradient, coupling, cryogenics

3788

T. Tanaka, K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, Y. Sumitomo
LEBRA, Funabashi, Japan

A cryogenic C-band photocathode RF electron gun cavity has been studied at Nihon University LEBRA in cooperation with KEK. The RF properties of a cold model measured at 20 K have shown good agreement with those expected from computer simulations using the cavity surface resistance predicted by the theory of the anomalous skin effect. Recent studies on the vacuum RF breakdown at high electric fields suggest that the temperature in the cavity surface during the high power RF pulse has a significant effect on the behavior of the breakdown rate. In order to investigate the breakdown property of the cryogenic cavity aiming at a very high accelerating field with as low breakdown rate as possible, one-dimensional simulations of the temperature rise in the cavity surface have been done for various combinations of the RF pulse width and the peak input RF power. The evaluation will be taken into consideration in the design of a new high power cryogenic cavity that has basically the same configuration with the cold model.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL061

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL063

RF and Thermo-Mechanical Considerations in Designing the Waveguide Iris Coupler for the Drift Tube Linac in the ORNL Spallation Neutron Source

GUI, DTL, simulation, vacuum

3796

S.W. Lee, Y.W. Kang
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT Battelle, LLC, under contract DE AC05 00OR22725 for the U.S.DOE
The Spallation Neutron Source (SNS) employs tapered ridge waveguide iris couplers to power six drift tube linac (DTL) cavity structures with pulsed RF systems using 2.5MW klystrons at 402.5MHz. All DTL iris couplers have been operating continuously for more than a decade without replacement. Transferring high RF energy to the cavities requires robust RF and mechanical performances with respect to power dissipation, electrical breakdown, and vacuum pressure. Considering the upcoming full 1.4MW operation and the future proton power upgrade (PPU) project, the structural design and the material selection needed to be reviewed for potential spare manufacturing. The existing design and the modified design with improvements to the coupler have been numerically studied. For the study, 3D models were used for RF and structural characterizations of the waveguide iris couplers on the DTL cavity. RF and thermo-mechanical co-simulations were performed to assess the effects of using the different materials and the structural modification.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL063

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL064

Burst-Mode UV Enhancement Cavity for Laser-Assisted Hydrogen Ion Beam Stripping at SNS

laser, resonance, experiment, controls

3799

A. Rakhman, Y. Liu
ORNL, Oak Ridge, Tennessee, USA

Funding: This work has been supported in part by U.S. DOE grant DE-FG02-13ER41967. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Recent success of laser-assisted charge exchange for 10 μs duration Hydrogen ion beams at SNS motivates laser development necessary for efficient stripping of 1.0 ms duration beam at full duty cycle. To overcome the laser power challenge, the interaction point was chosen inside an optical cavity. A doubly-resonant enhancement cavity and a novel locking technique have been developed, and a coherent enhancement of 402.5 MHz, 50 ps, 1.05 MW peak power ultraviolet (355 nm) laser pulses operating at 10-μs/10-Hz burst mode has been demonstrated. This will enable 1.0 ms duration laser macropulses at 60 Hz to be stored inside such a cavity to achieve efficient stripping at SNS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL064

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL065

Improving the Work Function of Nitrogen-Doped Niobium Surfaces for SRF Cavities by Plasma Processing

plasma, niobium, SRF, accelerating-gradient

3802

K.E. Tippey, R. Afanador, M. Doleans, S.-H. Kim, J.D. Mammosser, C.J. McMahan
ORNL, Oak Ridge, Tennessee, USA
M. Martinello
Fermilab, Batavia, Illinois, USA

Funding: DOE research grant FWP-ERKCSA2; DOE contract DE-AC05-00OR22725
Work function and surface chemistries of SiC-polished, electropolished, and nitrogen-doped niobium coupons were analyzed before and after plasma processing using a neon-oxygen gas mixture. These studies represent an initial enquiry into the feasibility of applying the plasma processing technique designed at ORNL for the Spallation Neutron Source (SNS) to the nitrogen-doped Nb cavities for the Coherent Light Source II (LCLS-II). Work function of all measured samples was increased after plasma processing, which indicates the strong potential of the plasma processing technique as a tool for increasing the accelerating gradient of nitrogen-doped cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL065

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL067

Room Temperature Measurements of Higher Order Modes for the SPS Prototype RF-Dipole Crabbing Cavity

HOM, dipole, simulation, luminosity

3805

S.U. De Silva, J.R. Delayen, H. Park
ODU, Norfolk, Virginia, USA
P. Berrutti
Fermilab, Batavia, Illinois, USA
N.A. Huque, H. Park
JLab, Newport News, Virginia, USA

LHC High Luminosity Upgrade will be developing two local crabbing systems to increase the luminosity of the colliding bunches at the ATLAS and CMS experiments. One of the crabbing systems uses the rf-dipole cavity design that will be crabbing the beam in the horizontal plane. The fully integrated crabbing cavity has two higher order mode couplers in damping those excited modes. Currently two sets of HOM couplers have been fabricated at Jefferson Lab for prototyping and testing with the LARP crabbing cavities. This paper presents the measurements of the higher order modes with the prototype HOM couplers carried out at room temperature.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL067

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL070

Multi-Physics Analysis of Two Bunchers for CIFNEF

simulation, beam-transport, target, neutron

3815

Q.Y. Tan, M.J. Easton, Q. Fu, P.P. Gan, H.P. Li, Y.R. Lu, Z. Wang
PKU, Beijing, People's Republic of China

CIFNEF(Compact Intense Fast NEutron Facility) project will accelerate and deliver a 5 MeV deuteron beam to the targets to produce high-intense neutrons. A 2.5 MHz pulsed deuteron beam with bunch width within 2 ns is needed on the targets at last. To fulfill the special requirements of the beam dynamics, two types of bunchers are adopted in the CIFNEF. One is a 10.156 MHz buncher used in the low energy beam transport (LEBT) line to longitudinally focus the 50 keV deuteron beam to the RFQ longitudinal acceptance with 4 kV effective voltage. A lumped element model is adopted because of the low frequency and it consists of an inductance coil in parallel with the capacitance of drift tube. The other one is an 81.25 MHz buncher used in the high energy beam transport (HEBT) line to longitudinally focus the 5 MeV deuteron beam to 2 ns. A QWR cavity with 2-gaps is used to provide 150 kV effective voltage. Thermal and structural analyses have been carried out on these two bunchers. Details of simulations of these two bunchers are presented and discussed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL070

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL074

Numerical Studies of Normal Conducting Deflecting Cavity Designs for the ELBE Accelerator

HOM, electron, experiment, impedance

3824

T.G. Hallilingaiah, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
A. Arnold, U. Lehnert, P. Michel
HZDR, Dresden, Germany

Currently, in the electron linac ELBE there is a single beam line. Therefore, at any given time only single user can use the beam. Moreover, as different user experiments require distinct beam intensity settings, not all the experiments fully utilize the 13 MHz CW beam capability of the facility. To utilize the full beam capacity, multiple beam lines can be established by using an array of transverse deflecting structures. For that, an RF cavity was the design choice due to its inherent advantages with respect to repeatability of the kick voltage amplitude and phase, and the possibility of CW operation in the MHz range. Potential design candidates are the CEBAF RF separator, the three proposed crab cavities for the HL-LHC upgrade project, and a novel NC deflecting cavity design. In this comparative study, the figures of merit of the cavities are computed from electromagnetic field simulations for a transverse voltage of 300 kV. This comparative study supported our selection of the deflecting cavity design for ELBE.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL074

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL076

Experimental Methods for the Assessment of NEG Pumps Working in Dust-Sensitive Environments

vacuum, SRF, experiment, background

3828

T. Porcelli, E. Maccallini, P. Manini, M. Mura, M.F. Urbano
SAES Getters S.p.A., Lainate, Italy

NEG pumps have been widely adopted by many accelerator facilities since decades. However, their use in dust-sensitive areas - such as superconductive radio frequency (SRF) cavities - has always been limited by concerns about accidental dust emission, which could induce detrimental field emission. As future machines will necessarily rely on highly-efficient SRF cavities, able to supply very high accelerating gradients, requirements in terms of particle release from vacuum components (e.g., pumps and valves) are becoming more and more stringent. At the same time, achieving stable ultra-high vacuum conditions is crucial, as condensed residual gas might also be a potential source of field emission. At present, a unified standard procedure to assess dust generation and propagation along a machine is still missing and discussions are ongoing in the vacuum community. Recent experimental measurements demonstrated the compatibility of sintered NEG pumps with ultra-clean environments, due to their intrinsic very low dust release. In parallel, in-situ tests performed at different accelerator facilities showed absence of dust contamination from NEGs and no impact on cavities efficiency.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL076

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL080

Parallel-Feed SRF Accelerator Structures

SRF, coupling, simulation, impedance

3835

P.B. Welander, Z. Li, M.H. Nasr, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515.
Development of SRF accelerator technology that enables both higher gradient and higher efficiency is crucial for future machines. While much of the recent R&D focus has been on materials and surface science, our aim is to optimize the cavity geometry to maximize performance with current materials. The recent demonstration of a highly efficient parallel-feed NCRF structure at SLAC has served as a proof-of-concept. Applied to SRF, such a structure could dramatically reduce power consumption while boosting the achievable gradient. Instead of coupled elliptical cells, our structure employs isolated reentrant cells. To feed RF power to the cavities, each cell is directly coupled to an integrated manifold. The structure is made in two parts, split along the beam axis, which are then joined. Such a structure has been fabricated from bulk Cu and tested at SLAC - designed for X-band, it operates at a record gradient of 150 MV/m. Adapting to SRF at 1.3 GHz and fabricating from Nb, such a cavity could achieve more than 50% lower RF loss and 40% higher gradient compared to the TESLA cavity. We will describe our simulations and propose an experimental roadmap for demonstrating this technology.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL080

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL081

A 3 GHz SRF Reduced-beta Cavity for the S-DALINAC

linac, SRF, operation, electron

3838

D.B. Bazyl, H. De Gersem, W.F.O. Müller
TEMF, TU Darmstadt, Darmstadt, Germany
J. Enders, S. Weih
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG through GRK 2128
In order to reduce the energy spread and to be able to use a 200 keV spin-polarized electron source, the initial part of the injector linac of the superconducting Darmstadt electron linear accelerator S-DALINAC needs to be upgraded. The decisions on the cavity type, number of cells and value of geometric beta are motivated. The main part of this work is dedicated to the mechanical design of the cavity. A precise evaluation of the mechanical characteristics of an SRF cavity is necessary during the design stage. The dependence of the resonant frequency of the fundamental mode on external mechanical loads needs to be investigated for developing the tuning procedures. The results of the multiphysics simulations and of the optimization of the mechanical design are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL081

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL084

An X-Band Lineariser for the CLARA FEL

FEL, simulation, wakefield, klystron

3848

L.S. Cowie, A.D. Brynes, J.K. Jones, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Apsimon, G. Burt, W.L. Millar
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
Ö. Mete
UMAN, Manchester, United Kingdom
A.J. Moss
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The CLARA FEL at Daresbury Laboratory will employ four S-band linacs to accelerate electron bunches to 250 MeV/c. In order to compress the bunch sufficiently to achieve peak currents suitable for FEL lasing, one must compensate for curvature imprinted on the longitudinal phase space of the bunch. For CLARA a harmonic RF linearization system has been designed to achieve this requirement. The linearization will be achieved by an X-band travelling wave cavity of the PSI/CERN design, which incorporates wake-field monitoring of the bunch position. A five-axis mover will align the cavity to the beam axis. Pulse compression of a 6 MW klystron pulse will provide the required power to achieve a 30 MV/m operational gradient.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL084

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL085

High Power RF Conditioning on CLARA

vacuum, linac, solenoid, multipactoring

3852

L.S. Cowie, D.J. Scott
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, W.L. Millar
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

The CLARA accelerator at Daresbury Laboratory will have 8 normal conducting RF cavities. Automating the high power RF conditioning of these cavities will mean a repeatable, research-lead process is followed. An auto-mated algorithm has been written in Python. A prototype algorithm was used to condition the first CLARA travel-ling wave linac in October 2017. The linac was success-fully conditioned over approximately 12 million pulses up to 27 MW for a 750 ns pulse. A more complex and robust algorithm was used to re-condition the standing wave 10 Hz photoinjector after a cathode change. The photoinjec-tor was conditioned to 10 MW for a 2.5 μs pulse in Feb-ruary 2018 over 2.1 million pulses. Conditioning method; differences for travelling and standing wave structures; difficulties and interesting phenomena are all discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL085

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL086

Superconducting Thin Film RF Measurements

SRF, vacuum, niobium, operation

3856

P. Goudket, L. Bizel-Bizellot, L. Gurran, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, L. Gurran
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Goudket, T. Junginger, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
L. Gurran, T. Junginger
Lancaster University, Lancaster, United Kingdom

As part of an ongoing programme of SRF Thin Films development, a radiofrequency (RF) cavity and cryostat dedicated to the measurement of superconducting coatings at GHz frequencies was designed to evaluate surface resistive losses on a flat sample. The resonator has now been used for measurements on Thin Film samples. Results from a test on a sample previously tested at Cornell University are presented. In order to simplify the measurements and achieve a faster turnaround, the experiment will be moved to a new cryostat fitted with a cryocooler. This will limit the measurements to low power only, but will allow a much faster sorting of samples to identify those that would benefit from further investigation. A description of the system and initial results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL086

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL089

Design, Assembly and Commissioning of a New Cryogenic Facility for Complex Superconducting Thin Film Testing

SRF, experiment, site, operation

3859

O.B. Malyshev, L. Bizel-Bizellot, K.D. Dumbell, P. Goudket, N. Pattalwar, S.M. Pattalwar, P. Pizzol, P.A. Smith, R. Valizadeh, S. Wilde
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P. Pizzol
The University of Liverpool, Liverpool, United Kingdom

An ongoing study on the superconducting thin films for future superconducting RF cavities requires an intense testing of various superconducting properties. We have designed, built and tested a new facility for complex superconducting thin film testing that includes: (1) RRR measurement with and without magnetic field, (2) planar and (3) tubular magnetic field penetration experiments, (4) a superconducting coaxial resonator for bulk niobium and superconducting thin film characterisation. The system is based on a closed cycle refrigerator, eliminating the need for liquid helium, thus making it simple and safe to operate. The details of the design and commissioning will be presented at the conference.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL089

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL101

Longitudinal Effects of Trapped Homs in Shanghai Coherent Light Facility

HOM, linac, impedance, FEL

3872

J.J. Guo, Q. Gu, H.T. Hou, J.H. Tan, M. Zhang
SINAP, Shanghai, People's Republic of China

Funding: Shanghai Institute of Applied Physics, Chinese Academy of Sciences
Shanghai Coherent Light Facility (SCLF), a superconducting accelerated structure-baesd FEL device, is now under development at Shanghai Institute of Applied Physics, Chinese Academy of Sciences. We investigate effects of cryogenic losses caused by trapped longitudinal high order modes (HOM). Results of calculations are presented for losses caused by HOMs excitation in the acceleration RF system of the continues-wave (CW) linac of SCLF.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL101

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL108

In-Situ Characterization of Normal Conducting RF Cavities in Solaris Light Source Storage Ring

HOM, storage-ring, simulation, ISOL

3891

P.B. Borowiec, A.I. Wawrzyniak
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
J. Björklund Svensson
Lund University, Division of Atomic Physics, Lund, Sweden

The SOLARIS 1.5 GeV storage ring is equipped with two 100 MHz active cavities and two 3rd harmonic passive cavities. They are in operation since 2015. For control of their respective working points, knowledge about cavity voltage and higher order mode (HOM) frequency spec-trum is mandatory. After their installation in the storage ring and connection of the RF feeder to a high power isolator and a transmitter, the influence of the external elements on the quality factor and the HOM spectrum should be verified with respect to simulations of a simpli-fied model of a stand-alone cavity. This paper will pre-sent results of in-situ cavity measurements to qualify the HOM placement and their quality factor. HOM meas-urements have been performed in the range 100 MHz to 1.3 GHz for active cavities and 300 MHz to 1.5 GHz for 3rd harmonic cavities at three different temperatures under ultra-high vacuum conditions for each cavity separately. The measurement and analysis methodology will also be presented

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL108

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL109

The New 118 MHz Cavity for RF Development Activities of the RF for Accelerator Laboratory at SLRI

simulation, HOM, coupling, impedance

3895

N. Juntong, K. Kittimanapun, P. Sunwong
SLRI, Nakhon Ratchasima, Thailand
A. Sutchada
Walailak University, Nakhon Si Thammarat, Thailand

The RF for accelerator laboratory is established at SLRI to perform RF related development activities of the current light source and the future synchrotron light facility in Thailand. One of activities is to build an in-house RF cavity. It will be used for testing of RF amplifier unit and the developed LLRF system. The cavity is a nose-cone pill-box cavity operating at 118 MHz and aiming at 100 kV gap voltage. Details of designing in particular the inner surface profile, the RF properties, the higher order modes properties, the RF power coupler, and the tuning mechanism will be presented with the manufacturing timeline.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL109

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL110

High-Power RF Test of Coaxial Couplers for the Injection Linac of XiPAF

vacuum, multipactoring, coupling, linac

3899

Y. Lei, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, H.Y. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China
J. Jiang, H. Li, C. Yu
Beijing Aerospace Guagntong Technology Co., Beijing, People's Republic of China

For the high-power RF test of the coaxial couplers which will be employed on the linac injector of the XiPAF (Xi'an Proton Application Facility) project, a high-power conditioning cavity was designed and manufactured [1]. There are some optimized aspects on the cavity and couplers to obtain better RF performance during the high-power testing process. The traveling-wave test and full-power-reflection test were executed to check whether the coupler can afford the enough power level for the linac operation, and whether only one coupler can afford the total power for the RFQ. The construction of the testing stand, optimization of RF parameters and results of high-power RF test are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL110

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL113

The Design of 1 MeV Proton LINAC Operating in CW

linac, proton, simulation, resonance

3905

N.V. Avreline
TRIUMF, Vancouver, Canada

Experimental results and computer simulations of electrodynamic and thermodynamic characteristics are presented for an accelerating structure that is excited in the TM010 mode and that has the accelerating channel of URAN-1M located in the diametric plane. The idea of using this structure in the particle accelerator URAN-1M, located at the Baikov Institute of Metallurgy and Materials Science, with the goal of increasing the average beam current is explored.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL113

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL118

Critical Fields of SRF Materials

niobium, FEL, interface, superconductivity

3921

T. Junginger
TRIUMF, Vancouver, Canada
T. Prokscha, Z. Salman, A. Suter
PSI, Villigen PSI, Switzerland
A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA

Nb3Sn and NbTiN are two potential alternative materials to niobium for superconducting RF cavities. In this study direct measurements of the magnetic penetration depth using the low energy muon spin rotation technique are presented, from which the lower critical field and the superheating field are derived. Comparison with RF data confirms that the lower critical field is not a fundamental limitation and predict a potential performance clearly exceeding current state of the art of niobium technology if the superheating field can be achieved. As a potential pathway to avoid premature vortex penetration and reaching the superheating field it is suggested to use a bilayer structure with the outer layer having a larger magnetic penetration depth.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL118

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL123

Fabrication and Test of β=0.3 325MHz Balloon Single Spoke Resonator

multipactoring, niobium, linac, TRIUMF

3934

Z.Y. Yao, J.J. Keir, D. Kishi, D. Lang, R.E. Laxdal, H.L. Liu, Y. Ma, B. Matheson, B.S. Waraich, Q. Zheng, V. Zvyagintsev
TRIUMF, Vancouver, Canada

A novel balloon variant of the single spoke resonator (SSR) has been designed, fabricated and tested at TRIUMF. The cavity is the β=0.3 325 MHz SSR1 prototype for the Rare Isotope Science Project (RISP) in Korea. The balloon variant is specifically designed to reduce the likelihood of multipacting barriers near the operating point. A systematic multipacting study led to a novel geometry, a spherical cavity with re-entrant irises plus a spoke. The balloon cavity provides competitive RF parameters and a robust mechanical structure. Cold tests demonstrated the principle of the balloon concept. The fabrication experience and the preliminary test results will be reported in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL123

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL126

Nitrogen Bake-out Procedures at the Vertical High-Temperature UHV-Furnace of the S-DALINAC

SRF, vacuum, niobium, linac

3937

R. Grewe, L. Alff, M. Arnold, J. Conrad, S. Flege, M. Major, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany

Funding: Work supported by the Federal Ministry of Education and Research through grant No. 05H15RDRBA.
As the performance limits of bulk Nb srf cavities are reached, our research is focused on materials with superior srf properties like Nb3Sn and NbN. Research on NbN resulted in the "nitrogen-doping" process used for increasing the quality factors of srf cavities for the LCLS-II project. This process leads to delta-phase Nb-N, a phase with higher critical sc parameters than bulk Nb. This phase is formed at temperatures of 800°C in nitrogen atmospheres of 10^-2 mbar. Other crystalline phases of NbN have even better sc parameters. We concentrate our research on applicability of delta-phase NbN for cavities. The delta-phase forms at temperatures of above 1300°C, which is more than most of the furnaces at accelerator facilites are capable of. Since 2005 the Institute for Nuclear Physics at the Technische Universität Darmstadt operates a high temperature vacuum furnace which has been upgraded to allow temperatures of up to 1750°C and bakeouts of niobium samples and cavities in nitrogen atmospheres. We will report on the current status of our research on nitrogen bake-out procedures on Nb samples. The samples have been analyzed at the Material Science Departement with SIMS, REM and XRD.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL126

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL127

Structural Investigations of Nitrogen-Doped Niobium for Superconducting RF Cavities

niobium, vacuum, ECR, experiment

3940

M. Major, L. Alff, M. Arnold, J. Conrad, S. Flege, R. Grewe, M. Mahr, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
KPH, Mainz, Germany

Funding: Work supported by the German Federal Ministry for Education and Research (BMBF) through grant 05H15RDRBA.
Niobium is the standard material for superconducting RF (SRF) cavities. Superconducting materials with higher critical temperature or higher critical magnetic field allow cavities to work at higher operating temperatures or higher accelerating fields, respectively. Enhancing the surface properties of the superconducting material in the range of the penetration depth is also beneficial. One direction of search for new materials with better properties is the modification of bulk niobium by nitrogen doping. In the Nb-N phase diagram the cubic delta-phase of NbN has the highest critical temperature (16 K). Already slight nitrogen doping of the alpha-Nb phase results in higher quality factors.* Nb samples were N-doped at the refurbished UHV furnace at IKP Darmstadt. Reference samples were annealed in 1 bar nitrogen atmosphere at different temperatures. In this contribution the results on the structural investigations (x-ray diffraction and pole figure, secondary ion mass spectroscopy, scanning electron microscopy) at the Materials Research Department of TU Darmstadt will be presented.
*Grassellino et al., Proc. SRF2015, MOBA06, 48.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL127

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL129

Magnetron Sputtering of Nb3Sn for SRF Cavities

SRF, site, target, controls

3946

MNS. Sayeed, H. Elsayed-Ali
ODU, Norfolk, Virginia, USA
G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA
M.J. Kelley, U. Pudasaini
The College of William and Mary, Williamsburg, Virginia, USA
M.J. Kelley
Virginia Polytechnic Institute and State University, Blacksburg, USA

Nb3Sn is a potential candidate for surface material of SRF cavities since it can enable the cavity to operate at higher temperatures with high quality factor and at an increased accelerating gradient. Nb-Sn films were deposited using magnetron sputtering of individual Nb and Sn targets onto Nb and sapphire substrates. The as-deposited films were annealed at 1200 °C for 3 hours. The films were characterized for their structure by X-ray Diffraction (XRD), morphology by Field Emission Scanning Electron Microscopy (FESEM), and composition by Energy Dispersive X-ray Spectroscopy (EDS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The surface resistivity was measured down to cryogenic temperature to determine the superconducting transition temperature and its width. The composition of the multilayered films was controlled by varying the thickness of the Nb and Sn layers. The films showed crystalline Nb3Sn phases with Tc up to 17.6 K.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL129

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL130

Effect of Deposition Temperature and Duration on Nb3Sn Diffusion Coating

SRF, niobium, experiment, superconductivity

3950

U. Pudasaini, M.J. Kelley
The College of William and Mary, Williamsburg, Virginia, USA
G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA
M.J. Kelley, J. Tuggle
Virginia Polytechnic Institute and State University, Blacksburg, USA

Funding: Partially authored by Jefferson Science Associates under contract no. DE¬AC05¬06OR23177. Work at College of William & Mary supported by Office of High Energy Physics under grant SC0014475.
Nb3Sn is a potential candidate to replace Nb in SRF accelerator cavities to reduce cost and advance perfor-mance. Tin vapor diffusion is the preferred technique to realize such cavities by growing a few microns thick Nb3Sn coating on the interior surface of the niobium cavity. The coating process typically uses temperatures of 1100-1200 °C for 3-6 hours. It is important to better understand the coating process, and optimize the coating parameters to overcome the current limitation on the performance of Nb3Sn coated SRF cavities. We investi-gate Nb3Sn coatings prepared in the temperature range of 900-1200 °C and duration of 3 - 12 hours using various material characterization tools. Variation of these pa-rameters appears to have notable effect on microstructure and topography of the obtained surface.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL130

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL131

Studies of Electropolishing and Oxypolishing Treated Diffusion Coated Nb3Sn Surfaces

niobium, SRF, experiment, superconductivity

3954

U. Pudasaini, M.J. Kelley
The College of William and Mary, Williamsburg, Virginia, USA
G.V. Eremeev, M.J. Kelley, C.E. Reece
JLab, Newport News, Virginia, USA
M.J. Kelley, J. Tuggle
Virginia Polytechnic Institute and State University, Blacksburg, USA

The Nb3Sn-coated cavities aim to enhance perfor-mance and significantly reduce cost. Their fabrication involves tin vapor diffusion coating of Nb3Sn on the interior surface of a Nb cavity. Controlled removal of first few layers to obtain a smoother and cleaner surface could be desirable to improve the high field RF perfor-mance. Our first results from the application of elec-tropolishing and oxypolishing techniques on Nb3Sn-coated surfaces indicated reduced surface roughness, and the surface composition appeared nominally unchanged. Systematic studies explore the effect of different polish-ing parameters into the roughness and composition. We present the latest results from SEM/EDS and AFM studies of Nb3Sn-coated samples treated with electropolishing and oxypolishing.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL131

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL133

LASE Surfaces for Mitigation of Electron Cloud in Accelerators

electron, laser, vacuum, experiment

3958

B.S. Sian
UMAN, Manchester, United Kingdom
O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Vacuum chamber surface characteristics such as the photon and secondary electron yields (PEY and SEY) are critical parameters in the formation of an electron cloud, a serious problem that limits the performance of proton and positron accelerators. A few years ago it was discovered by the Vacuum Solutions Group at Daresbury laboratory that Laser Ablation Surface Engineering (LASE) could provide surfaces with SEY<1 [1,2]. The LASE surfaces are considered as a baseline solution for electron cloud miti-gation in the Future Circular Collider (FCC). However, these surfaces are undergoing further optimisation for the FCC application. While keeping SEY<1 the surfaces should meet the following criteria: Low outgassing, Low particulate generation and low surface resistance. In this paper we will report a number of new surfaces created using the LASE technique with different laser parameters (wavelength, scan speed, pitch, repetition rate, power, and pulse length) and their effect on the SEY, surface re-sistance and vacuum properties, etc

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL133

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL134

Commissioning of the Prototype C75 Cavities in a CEBAF Cryomodule

cryomodule, MMI, HOM, operation

3961

M.A. Drury, G. Cheng, G. Ciovati, E. Daly, G.K. Davis, J. Guo, R.A. Legg, F. Marhauser, T. Powers, A.V. Reilly, R.A. Rimmer
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Prototype cavities have been built at Jefferson Lab to increase the energy of future refurbished CEBAF cryomodules to 75 MeV in the most cost efficient way. Three such cavities, named "C75", have been built from ingot Nb material of different purity and have been processed and tested. The two better performing cavities have been assembled into a "cavity pair" and installed in the latest refurbished original CEBAF cryomodule. The cryomodule was installed and commissioned in CEBAF. The results from the commissioning of the C75 cavities, compared with the original CEBAF cavities, are presented in this article. The vertical test performance of the C75 cavities was preserved in the cryomodule with one of the cavities achieving the performance specification of an accelerating gradient of 19 MV/m with a quality factor of ~8×10⁹ at 2.07 K. The performance in terms of microphonics and tuner operation was similar to that of original CEBAF cavities, as expected, and the high-order modes are properly damped. The quality factor of the two C75 cavities was the highest achieved in a CEBAF cryomodule, possibly due to the better magnetic flux expulsion of ingot Nb than standard fine-grain Nb.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL134

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL137

Acceptance Testing of the First Group of LCLS II Cryomodules at Jefferson Lab

cryomodule, operation, HOM, radiation

3965

M.A. Drury, E. Daly, N.A. Huque, L.K. King, M.D. McCaughan, A.D. Solopova
JLab, Newport News, Virginia, USA
J. Nelson
SLAC, Menlo Park, California, USA

Funding: This work was supported by the LCLS-II Project and the US Department of Energy, Contract DE-AC02-76SF00515.
The Thomas Jefferson National Accelerator Facility is currently engaged, along with several other Department of Energy (DOE) national laboratories, The Thomas Jefferson National Accelerator Facility is currently engaged, along with several other Department of Energy (DOE) national laboratories, in the Linac Co-herent Light Source II project (LCLS II). The SRF Insti-tute at Jefferson Lab is currently building 17 cryomod-ules for this project. The cryomodules are TESLA style cryomodules that have been modified for continuous wave (CW) operation and for other LCLS II specifica-tions. Each cryomodule contains eight 9-cell cavities with coaxial power couplers operating at 1.3 GHz. The cryomodules also contains a magnet package that con-sists of a quadrupole and two correctors. These cryomod-ules will be tested in the Cryomodule Test Facility (CMTF) at Jefferson Lab before shipment to the Stanford Linear Accelerator (SLAC). Acceptance testing of the LCLS II cryomodules began in December 2016. Seven cryomodules have currently completed Acceptance test-ing. This paper will summarize the results of those tests.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL137

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL140

Rework Recipe Development, Analysis and Results of Select 9-Cell Cavities for LCLS-II

embedded, niobium, site, linac

3968

A.D. Palczewski, K. Macha, H. Park, C.E. Reece, K.M. Wilson
JLab, Newport News, Virginia, USA
A. Burrill, D. Gonnella
SLAC, Menlo Park, California, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The SLAC National Accelerator Laboratory is currently constructing a major upgrade to its accelerator, the Linac Coherent Light Source II (LCLS-II). Several Department of Energy laboratories, including the Thomas Jefferson National Accelerator Facility (JLab) and Fermi National Accelerator Laboratory (FNAL), are collaborating in this project. The cryomodules for this project each consist of eight 1.3-GHz cavities produced by two vendors, Research Instruments GmbH in Germany (RI*) and Ettore Zanon S.p.a. in Italy (EZ*), using niobium cell material from Tokyo Denkai Co., Ltd. (TD) and Ningxia Orient Tantalum Industry Co., Ltd. (OTIC/NX)). During the initial production run, cavity performance from one of the vendors (Vendor A) was far below expectation. All the cavities had low Q0, later attributed to minimal EP as well as high-flux-trapping NX material, early quench behaviour below 18 MV/m, with many having Q0 roll-off at 12-16 MV/m. Production was stopped multiple times over the following 6 months, with test batches of cavities being made to ascertain the root cause of the problem. The final root cause of the problem was found to be inappropriate grinding of the RF surface prior to welding which left normal conducting inclusions in the surface. In addition, most cavities showed internal and external weld spatter which required post weld grinding and a very rough surface from operating the electropolishing machine in an etching rather than polishing regime. All issues have been corrected on new cavities and rework is underway on the originally effected cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL140

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL141

Optimizing Procurement Strategies for LCLS-II

cryomodule, niobium, HOM, status

3972

K.M. Wilson, G. Cheng, E. Daly, J.A. Fitzpatrick, N.A. Huque, M.L. Laney, F. Marhauser, A.D. Palczewski, H. Park, T. Peshehonoff, G. Tenbusch, M. Torres
JLab, Newport News, Virginia, USA

Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract DE-AC02-76SF00515
The SLAC National Accelerator Laboratory is currently constructing a major upgrade to its accelerator, the Linac Coherent Light Source II (LCLS-II). Several Department of Energy national laboratories, including the Thomas Jefferson National Accelerator Facility (JLab), are participating in this project. JLab is responsible for procuring a number of critical components. Over the course of this project, JLab has evolved several procurement strategies to minimize risk and improve performance while working within the constraints of budget and schedule. This paper discusses the impact of procurement choices on project technical success.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL141

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL143

Commissioning of JLab Vertical Cavity Processing System for SRF Nb Single Cell and Multicell Cavity With HF-Free Pulse-Reverse Electopolishing

SRF, controls, niobium, MMI

3978

H. Tian, M. Lester, J. Musson, H.L. Phillips, C.E. Reece, C. Seaton
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
Pulse reversed electropolishing of niobium SRF cavities, using a dilute aqueous H2SO4 electrolyte without HF yields equivalent RF performance with traditional EP. Comparing with present EP process for Nb SRF cavity which uses 1:10 volume ratio of HF (49%) and H2SO4 (98%), pulse reverse EP (also known as bipolar EP (BPEP)) is ecologically friendly and uses relatively benign electrolyte options for cavity processing. In this study, we report the commissioning of a new vertical cavity processing system for SRF Nb single cell and multi-cell cavities with HF-free pulse-reverse electropolishing at Jefferson Lab, together with RF test of cavities being processed. We report the scale-up challenges and interpretations from process R&D to implementation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL143

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL144

952.6 MHz SRF Cavity Development for JLEIC

HOM, damping, electron, SRF

3982

R.A. Rimmer, W.A. Clemens, F. Fors, J. Guo, F.E. Hannon, J. Henry, F. Marhauser, L. Turlington, H. Wang, S. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
JLab is developing new SRF cavity designs at 952.6 MHz for the proposed Jefferson Lab Electron-Ion Collider (JLEIC). New cavities will be required for the ion ring, cooler ERL and booster and eventually for an upgrade of the electron ring to allow the highest possible bunch collision rate. The challenges include the need for high fundamental mode power couplers and strong HOM damping, with high HOM power capability. Initial focus is on the cooler ERL 5-cell cavity as this is a critical component for the strong, high energy, bunched-beam cooling concept. 1-cell and 5-cell Nb prototype cavities have been designed and fabricated. Details concerning the cavity fabrication and test results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL144

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL145

Magnetron R&D toward the Amplitude Modulation Control for SRF Accelerator

injection, controls, simulation, SRF

3986

R.A. Rimmer, T. E. Plawski, H. Wang
JLab, Newport News, Virginia, USA
A. Dudas, S.A. Kahn, M.L. Neubauer
Muons, Inc, Illinois, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and SBIR grant DE-SC0013203
The scheme of using a high efficiency magnetron to drive a superconducting radio frequency (SRF) accelerator cavity needs not only the injection phase locking but also the amplitude modulation to compensate the cavity's microphomics caused cavity voltage change and the beam loading variation. To be able to do a fast and efficient modulation, the magnetron's magnetic field has to be trimmed by an external coil to compensate the frequency pushing effect due to the anode current change [1]. A low eddy current magnetron body has been designed and built [2]. This paper will present the analytical prediction, simulation and experimental results on the 2.45 GHz magnetron test stand with the modulation frequency up to 1 kHz. In addition, the progresses on the injection lock to a copper cavity, new 1497 MHz magnetron prototype, 13 kW high power magnetron test stand development and newly built low level RF (LLRF) controller for the amplitude modulation will be reported.
[1] M. Neubauer et al, THPIK123, Proceedings of IPAC 2017, Copenhagen, Denmark
[2] S. A. Kahn et al, THPIK121, Proceedings of IPAC 2017, Copenhagen, Denmark

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL145

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL146

802 MHz ERL Cavity Design and Development

SRF, collider, electron, hadron

3990

F. Marhauser, S. Castagnola, W.A. Clemens, J.G. Dail, P. Dhakal, F. Fors, J. Henry, R.A. Rimmer, L. Turlington, R.S. Williams
JLab, Newport News, Virginia, USA
R. Calaga, K.M. Dr. Schirm, E. Jensen
CERN, Geneva, Switzerland

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and CERN Contract NR. KE3080/ATS
In the framework of a collaboration between CERN and JLab, an SRF accelerating cavity for energy recovery linacs operating at 802 MHz was developed in the context of the CERN's Large Hadron electron Collider (LHeC) design study. A single-cell and a five-cell cavity from fine grain high RRR niobium were built at JLab to validate the basic RF design in vertical tests. Two copper single-cell cavities were produced in parallel for R&D purposes at CERN. The cavity design has since been adapted as baseline for the main linac cavities in the proposed Powerful Energy Recovery Linac Experiment facility (PERLE) at Orsay. Details concerning the cavity fabrication and test results for the Nb cavities are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL146

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL148

Status of High Efficiency Klystron Development in TETD

klystron, electron, simulation, bunching

3993

Y. Okubo, S. Fujii, K. Suzuki, T.E. Tanaka
Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan

TETD (Toshiba Electron Tubes and Devices Co., Ltd.) has been developing a high efficiency klystron improved bunch quality by the multi-stage of core oscillation design. For feasibility study, an S-band 7.5 MW klystron has been designed with the efficiency of more than 60% at 1.8μperveance. The first prototype was fabricated by modifying the interaction section of a commercial model to enhance the efficiency from 45% to 60%. The klystron was tested in June 2017, and 57% of efficiency at 6 MW output power was demonstrated. We are developing the second prototype which has the improved design for the higher efficiency at 7.5 WM output power. The design details and the test results of the first prototypes are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL148

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL151

Progress in Understanding Breakdown Characteristics of X-Band Choke-Mode Structures

timing, experiment, HOM, operation

4002

X.W. Wu, D.Z. Cao, H.B. Chen, J. Shi, H. Zha
TUB, Beijing, People's Republic of China
T. Abe, T. Higo, S. Matsumoto
KEK, Ibaraki, Japan

Funding: National Natural Science Foundation of China (Grant No. 11135004).
As one of the higher-order-mode (HOM) damping structures, X-band choke-mode accelerating structures had been studied for several years. However, the breakdown characteristics of the X-band choke are still unknown. Five different single-cell choke-mode accelerating structures and one reference structure were designed, fabricated and high-gradient tested to study the related RF breakdown characteristics. The absence of field emission current flash was proposed to be the sign of breakdowns occurring inside the choke, this was verified by the post-mortem observation. Evaluation of the breakdown rate revealed that there is memory effect with pulse width and electric field. The breakdown rate in a single RF pulse did not have the 5th order pulse width and 30th order electric field dependency predicted by the empirical formula.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL151

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL152

Study of X-Band Phase Shifter Using Ferrite Material

GUI, simulation, coupling, insertion

4005

Y.L. Jiang, D.Z. Cao, H.B. Chen, J. Shi, P. Wang, H. Zha
TUB, Beijing, People's Republic of China

Ferrite has the feature of the permeability depended on the external static magnetic field, thus could be used to shift the phase of the propagating radio frequency (RF) signal. In this paper, we introduce a novel design of ferrite-based RF phase shifter. The design changes the resonant frequency of a ferrite-filled pill-box cavity to implement the phase changing. This design has a lower local RF field and a higher sensitivity on the phase changing than those of waveguide phase shifter, which may bring advantages such as higher power capacity, fast changing speed and lower insertion loss. Theory and simulation results are also presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL152

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL153

High Power Test of the S-Band Spherical Pulse Compressor at Tsinghua University

FEL, coupling, polarization, klystron

4008

P. Wang, D.Z. Cao, H.B. Chen, C. Cheng, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

We designed, fabricated and high power tested an S-band spherical pulse compressor for the high-power test facility at Tsinghua University. The pulse compressor comprises a spherical resonant cavity with an unloaded quality factor of 100, 000 and an RF polarizer with two rectangular ports and a circular port. To achieve high efficiency and large power gain, the coupling coefficient was optimized to 8 with input pulse length of 3.6 us and compression ratio of 12. After conditioning the RF system, the pulse compressor generated RF pulses with peak power of more than 400MW. And during the operation, the pulse compressor has very low breakdown rate and was extremely stable.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL153

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL155

Fabrication and Cold Test of the Correction Cavity Chain for Klystron-Based CLIC

operation, polarization, klystron, linear-collider

4014

P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

A proposed RF scheme based on correction cavity chain and storage cavity (CC-SC scheme) for klystron-based CLIC has the ability to generate flat output pulses. In the scheme, the correction cavity chain modulates the amplitude of the input pulse, while the storage cavity compresses the amplitude-modulated pulse. Resonant cavities of the correction cavity chain are of a relatively low unloaded quality factor and of small size, which results in the compactness of the RF scheme. The first prototype of a correction cavity chain was fabricated and cold tested at Tsinghua University and then delivered to CERN for high power test. Both the results of the cold and high power tests show that the correction cavity chain is of good performance. Feasibility and stability of the pulse compression system based on CC-SC scheme were demonstrated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL155

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL157

Investigation of Transverse Wakefield and Beam Break Up Effect in Irradiation Linacs

wakefield, experiment, linac, simulation

4020

X.C. Meng, H.B. Chen, J. Shi, Z.H. Wang, H. Zha, S.X. Zheng
TUB, Beijing, People's Republic of China
G.H. Li, J.S. Liu, Y.H. Liu
NUCTECH, Beijing, People's Republic of China

Study of beam break up effect in linacs has been done in recent years. The beam-induced high order dipolar modes, especially the TM11-like mode were investigated for the linacs both in travelling wave and backward trav-elling wave. Measurements of beam-break up in a travel-ling wave linac were carried out and results are discussed. Moreover, a theoretical model was developed for the irradiation linacs to study the detailed interaction be-tween the transverse wakefield and the electron beam.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL157

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL158

Development of an Half-Cell Accelerating Structure in Tsinghua

simulation, GUI, alignment, radiation

4023

M.M. Peng, W. Gai, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

The half-cell high gradient accelerating structure is attractive for its easy manufacturing and good alignment. A structure with 12 cells has been designed for the frequency of 11.424 GHz and a cold test will be conducted. Two different mechanical factory manufacture with same machining drawing and the results will be compared.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL158

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF007

Commissioning of the Hybrid Superconducting/Normal Conducting RF System in the Diamond Storage Ring

storage-ring, operation, LLRF, HOM

4042

C. Christou, A.G. Day, P. Gu, P.J. Marten, S.A. Pande, D. Spink, A. Tropp
DLS, Oxfordshire, United Kingdom

Two 500 MHz HOM damped normal conducting cavities have been installed in the Diamond storage ring to ensure continuity of operation of Diamond in the event of a failure of one of the two existing superconducting cavities. Following receipt from the manufacturer, the cavities were incorporated into an assembly including vacuum pumping, cooling and interlocked diagnostics and then tested for vacuum integrity and RF performance. Both cavities were then conditioned up to high power in Diamond's RF test facility before being installed in the storage ring in August and November 2017. Conditioning and operation has been carried out using a new digital LLRF system. Results of acceptance tests and commissioning with power and beam are presented, together with the current status of the hybrid RF system and options for further improvement of the system in the near future.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF007

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF024

Commissioning and Operation of FAST Electron Linac at Fermilab

electron, cryomodule, experiment, MMI

4096

A.L. Romanov, C.M. Baffes, D.R. Broemmelsiek, K. Carlson, D.J. Crawford, N. Eddy, D.R. Edstrom, E.R. Harms, J. Hurd, M.J. Kucera, J.R. Leibfritz, I.L. Rakhno, J. Reid, J. Ruan, J.K. Santucci, V.D. Shiltsev, G. Stancari, R.M. Thurman-Keup, A. Valishev, A. Warner
Fermilab, Batavia, Illinois, USA

We report results of the beam commissioning and first operation of the 1.3 GHz superconducting RF electron linear accelerator at Fermilab Accelerator Science and Technology (FAST) facility. Construction of the linac was completed and the machine was commissioned with beam in 2017. The maximum total beam energy of about 300 MeV was achieved with the record energy gain of 250 MeV in the ILC-type SRF cryomodule. The pho-toinjector was tuned to produce trains of 200 pC bunches with a frequency of 3 MHz at a repetition rate of 1 Hz. This report describes the aspects of machine commission-ing such as tuning of the SRF cryomodule and beam optics optimization. We also present highlights of an experimental program carried out parasitically during the two-month run, including studies of wake-fields, and advanced beam phase space manipulation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF024

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF028

Coherent Stacking Scheme for Inverse-Compton Scattering at MHz Repetition Rates

laser, simulation, coupling, feedback

4103

P. Piot, D. Mihalcea
Northern Illinois University, DeKalb, Illinois, USA
T.J. Campese, A.Y. Murokh
RadiaBeam Systems, Santa Monica, California, USA
D. Mihalcea, P. Piot, J. Ruan
Fermilab, Batavia, Illinois, USA

Funding: Work sponsored by the DNDO award 2015-DN-077-ARI094 to Northern Illinois University and US DOE contract DE-AC02-07CH11359 to Fermilab.
An experiment to produce 1-MeV gamma rays via Compton back-scattering of infrared photons on 250-MeV electron bunches is currently in preparation at the Fermilab Accelerator Science & Technology (FAST) facility. To increase the gamma-ray flux the energy of the infrared laser pulses are planned to be amplified within the interaction region using a resonant cavity. This passive amplifier composed of a Fabry-Perot cavity will allow the laser pulse bunches to coherently and constructively stack. Our estimates, based on theoretical models, show that the laser pulse energy can be increased from approximately 1-2 mJ at the exit of the last active amplifier to 5 -10 mJ at the interaction point when the laser repetition rate is set at the nominal value of 3 MHz. This paper details the cavity design option(s) and associated wave-optic simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF028

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF030

VSR Injector Upgrade at BESSY II

booster, injection, storage-ring, kicker

4110

T. Atkinson, P. Goslawski, J.G. Hwang, M. Ries
HZB, Berlin, Germany
T. Flisgen, T. Mertens
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany

BESSY VSR is a fully funded project at the Helmholtz-Zentrum in Berlin (HZB). The objective is to produce simultaneously both long and short pulses in the storage ring. The implications for the existing injector systems and the upgrade strategy are presented. Envisaged is a global upgrade which includes additional accelerating structures to reduce the bunch length in the booster, orbit measurements and implementing longitudinal feedback.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF030

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF032

Preparation and Testing of the BERLinPro Gun 1.1 Cavity

gun, cathode, pick-up, niobium

4117

H.-W. Glock, J. Knobloch, A. Neumann, Y. Tamashevich
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
For the BERLinPro energy recovery LINAC, HZB is developing a superconducting 1.4-cell electron gun, which, in its final version, is planned to be capable of CW 1.3 GHz operation with 77 pC/bunch. For this purpose a series of three superconducting cavities, denoted as Gun 1.0, Gun 1.1 (both designed for 6 mA) and Gun 2.0 (100 mA) is foreseen. Here the status of the Gun 1.1 cavity is described, including results of the recent vertical testing. Lessons learned from the production and preparation process are summarized, also in order to identify issues critical for the production of Gun 2.0.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF033

Design of the Beamline Elements in the BESSY VSR Cold String

synchrotron, HOM, shielding, operation

4123

H.-W. Glock, F. Glöckner, J. Knobloch, E. Sharples, A.V. Tsakanian, A.V. Vélez
HZB, Berlin, Germany
T. Flisgen
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
The four SRF cavities in the BESSY VSR module will be linked by bellows, which will be equipped with inner coaxial shielding pipes to prevent both parasitic fundamental mode losses and beam-induced heating. The central bellow will also act as a collimator for synchrotron radiation generated in the closest upstream dipole magnet. Additional bellows at the module's ends are needed to connect with the warm BESSY beam pipe. Outside the module the beam pipe cross section transitions will be located, which will be equipped with toroidal HOM absorbing elements. In the paper the recent design considerations and specifications for all those components will be described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF033

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF034

Status Report of the Berlin Energy Recovery Linac Project BERLinPro

gun, SRF, cathode, vacuum

4127

M. Abo-Bakr, W. Anders, Y. Bergmann, K.B. Bürkmann-Gehrlein, A.B. Büchel, P. Echevarria, A. Frahm, H.-W. Glock, F. Glöckner, F. Göbel, B.D.S. Hall, S. Heling, H.-G. Hoberg, A. Jankowiak, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, G. Kourkafas, J. Kühn, B.C. Kuske, J. Kuszynski, A.N. Matveenko, M. McAteer, A. Meseck, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, L. Pichl, J. Rahn, M.A.H. Schmeißer, O. Schüler, M. Schuster, J. Ullrich, A. Ushakov, J. Völker
HZB, Berlin, Germany
A. Bundels
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany

Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the last year's progress, including the comissioning of the gun module as the first SRF component to be installed in BERLinPro.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF034

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF036

Status of the Conceptual Design of ALS-U

lattice, emittance, vacuum, kicker

4134

C. Steier, A.P. Allézy, A. Anders, K.M. Baptiste, E.S. Buice, K. Chow, G.D. Cutler, S. De Santis, R.J. Donahue, D. Filippetto, J.P. Harkins, T. Hellert, M.J. Johnson, J.-Y. Jung, S.C. Leemann, D. Leitner, M. Leitner, T.H. Luo, H. Nishimura, T. Oliver, O. Omolayo, J.R. Osborn, G.C. Pappas, S. Persichelli, M. Placidi, G.J. Portmann, S. Reyes, D. Robin, F. Sannibale, C. Sun, C.A. Swenson, M. Venturini, S.P. Virostek, W.L. Waldron, E.J. Wallén
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The ALS-U conceptual design promises to deliver diffraction limited performance in the soft x-ray range by lowering the horizontal emittance to about 70 pm rad resulting in two orders of brightness increase for soft x-rays compared to the current ALS. The design utilizes a nine bend achromat lattice, with reverse bending magnets and on-axis swap-out injection utilizing an accumulator ring. This paper shows some aspects of the completed conceptual design of the accelerator, as well as some results of the R&D program that has been ongoing for the last years.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF036

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF038

Status of the BESSY VSR Project

vacuum, operation, SRF, electron

4138

P. Schnizer, W. Anders, Y. Bergmann, P. Goslawski, H. Hartmut, A. Jankowiak, J. Knobloch, A. Neumann, K. Ott, M. Ries, A. Schälicke, A.V. Vélez
HZB, Berlin, Germany

BESSY VSR is set out to provide a variable pulse pattern to the BESSY II users. This project is now fully funded and heading into its implementation phase. The pulse pattern, consisting of long and short pulses, require inserting cavities providing a 3rd and a 3.5th harmonic of the fundamental harmonic of the ring. Therefore 1.5 and 1.75 GHz cavities are developed with appropriate higher order mode damping spectrum. Similarly the BESSY II ring and injector chain has to be upgraded to provide appropriate diagnostics and increase the injection efficiency. In this paper we give the current status of the project and give an overview of scientific challenges currently being tackled.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF038

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF039

Study of Magnesium Photocathodes for Superconducting RF Photoinjectors

laser, gun, cathode, SRF

4142

R. Xiang, A. Arnold, P.N. Lu, P. Murcek, J. Teichert, H. Vennekate
HZDR, Dresden, Germany

Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
The superconducting RF photoinjector (SRF Gun II) has successfully served for the ELBE user facility at HZDR. Nevertheless, the quality of photocathodes is one of the most critical issues in improving the stability and reliability for its application. Magnesium has a comparably low work function (3.6 eV) and shows a quantum efficiency up to 0.3% after laser cleaning. However, the present cleaning process with a high intensity laser beam is time consuming and produces unwanted surface roughness, which leads to a higher thermal emittance. Thermal treatment and Excimer laser cleaning for Mg cathodes are investigated as alternative methods. In this work, the new cleaning procedures are tested and optimized, and the quantum efficiency of Mg samples with different microstructure, composition and suppliers are compared.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF039

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF041

Low Emittance Lattice for PF-AR

optics, emittance, injection, operation

4148

N. Higashi, K. Harada, S. Nagahashi, N. Nakamura, T. Obina, R. Takai, H. Takaki
KEK, Ibaraki, Japan
K. Hirano
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

PF-AR is a synchrotron-type 6.5 GeV light source in KEK. The user-run was started in 1987, and the lattice is almost the same as the original one. Now we consider the emittance improvement to enlarge the horizontal tune advance in the normal cell. Thanks to this manipulation, the emittance will be improved to about a half of the current value.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF041

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF056

Optimisation Study of the Fabry-Pérot Optical Cavity for the MARIX/BRIXS Compton X-Ray Source

laser, electron, gun, photon

4192

I. Drebot, A. Bacci, F. Broggi, S. Cialdi, C. Curatolo, D. Giannotti, D. Giove, A.R. Rossi, L. Serafini, M. Statera, V. Torri
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Bosotti, P. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
R. Calandrino, A. Delvecchio
HSP, Milan, Italy
P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi
INFN-Ferrara, Ferrara, Italy
A. Esposito, L. Faillace, A. Gallo, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
G. Galzerano, E. Puppin, A. Tagliaferri
Politecnico/Milano, Milano, Italy
G. Mettivier, P. Russo
UniNa, Napoli, Italy
V. Petrillo, F. Prelz, M. Rossetti Conti
Universita' degli Studi di Milano & INFN, Milano, Italy
M. Placidi, G. Turchetti
Bologna University, Bologna, Italy
A. Sarno
INFN-Napoli, Napoli, Italy

We present the study of the optimization of the optical cavity parameters, in order to maximise the flux of scattered photons in the Compton scattering process. In the optimisation, we compensate the losses of the photon number due to the elliptical shape of the laser pulse in optical cavity with a high focusing electron beam.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF056

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF057

Multi Colour X-Gamma Ray Inverse Compton Back-Scattering Source

laser, electron, radiation, photon

4196

I. Drebot, S. Cialdi, D. Giannotti, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
R. Calandrino
HSP, Milan, Italy
P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi
INFN-Ferrara, Ferrara, Italy
G. Galzerano
Politecnico/Milano, Milano, Italy
V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy

We present a simple and new scheme for producing multi colour Thomson/Compton radiation with the possibility of controlling separately their polarization, based on the interaction of one single electron beam with two and more laser pulses that can come from the same laser setup or from two different lasers system and that collide with the electrons at different angle inside one optical cavity. One of the most interesting cases for medical applications is to provide two X-ray pulses across the iodine K-edge at 33.2 keV. The iodine is used as contrast medium in various imaging techniques and the availability of two spectral lines accross the K-edge allows one to produce subtraction images with a great increase in accuracy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF057

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF058

The MariX source (Multidisciplinary Advanced Research Infrastructure with X-rays)

electron, FEL, gun, radiation

4199

V. Petrillo, N. Piovella
Universita' degli Studi di Milano, Milano, Italy
A. Bacci, F. Castelli, S. Cialdi, C. Curatolo, I. Drebot, D. Giannotti, D. Giove, C. Meroni, A.R. Rossi, L. Serafini, M. Statera, V. Torri
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Bosotti, F. Broggi, F. Groppi, P. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
R. Calandrino, A. Delvecchio
HSP, Milan, Italy
F. Camera, S. Coelli, G. Onida, B. Paroli, L. Perini, F. Prelz, M. Rossetti Conti, F. Tomasi
Universita' degli Studi di Milano & INFN, Milano, Italy
P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi
INFN-Ferrara, Ferrara, Italy
A. Castoldi, G. Ghiringhelli, C. Guazzoni, M. Moretti, E. Pinotti
Polytechnic of Milan, Milano, Italy
S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Esposito, A. Gallo, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
L. Faillace
RadiaBeam, Santa Monica, California, USA
G. Galzerano, E. Puppin, A. Tagliaferri
Politecnico/Milano, Milano, Italy
G. Mettivier, P. Russo
UniNa, Napoli, Italy
M. Placidi
LBNL, Berkeley, California, USA
G. Rossi
Università degli Studi di Milano, Milano, Italy
R.I. Saban
CERN, Geneva, Switzerland
A. Sarno
INFN-Napoli, Napoli, Italy
F. Stellato
INFN - Roma Tor Vergata, Roma, Italy
G. Turchetti
Bologna University, Bologna, Italy

MariX (Multidisciplinary advanced research infra-structure with X-rays) is a joint project of INFN and University of Milan, aiming at developing a twin X-ray Source of advanced characteristics for the future Sci-entific Campus of the University of Milan. Presently in its design study phase, it will be built in the post Expo area located in north-west Milan district. The first component of the X-source MariX is BriXS (Bright and compact X-ray Source), a Compton X-ray source based on superconducting cavities technology for the electron beam with energy recirculation and on a laser system in Fabry-Pérot cavity at a repetition rate of 100 MHz, producing 20-180 keV radiation for medical applications. The BriXS accelerator is also serving as injector of a 3.8 GeV superconductive linac, driving a X-ray FEL at 1 MHz, for providing coherent, moderate flux radiation at 0.3-10 KeV at 1 MHz. Scientific case, layout and typical parameters of MariX will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF058

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF062

Smith-Purcell Radiation for Bunch Length Measurements at the Injection of MESA

radiation, detector, electron, operation

4213

P. Heil
IKP, Mainz, Germany
K. Aulenbacher
HIM, Mainz, Germany

Funding: Federal Ministry of Education and Research
MELBA is a test apparatus for the injector of the energy recovering, superconducting accelerator MESA in Mainz. A chopper-buncher system containing two circularly deflecting cavities and a first and second harmonic buncher cavity have been built. They serve to produce short bunches with a longitudinal extension < 600 μm (one degree of RF-phase) in the longitudinal focus for beam currents of up to 10mA. We intend to use Smith-Purcell Radiation (SPR) to test this arrangement. SPR is generated if a charged particle passes close to a periodic metallic structure, e.g. a grating. The signal has a coherent part which increases its intensity quadratically with the bunch charge if the bunch length is smaller than or comparable to the grating period. Different gratings can be placed below the electron beam to determine the length of the electron bunches. This measurement is non-destructive. The generated THz radiation will be observed with a bolometer cooled down to 4.2K which offers sufficient sensitivity in our regime of operation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF062

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF063

The MESA 15 kW cw 1.3 GHz Solid State Power Amplifier Prototype

operation, experiment, SRF, linac

4216

R.G. Heine, F. Fichtner
IKP, Mainz, Germany

The Mainz Energy recovering Superconducting Accelerator MESA is a multi-turn energy recovery linac with beam energies in the 100 MeV regime currently designed and build at Institut für Kernphysik (KPH) of Johannes Gutenberg-Universität Mainz. The main accelerator consists of two superconducting Rossendorf type modules, while the injector MAMBO (MilliAMpere BOoster) relies on normal conducting technolgy. The high power RF system is planned completely in solid state technology. With the high power demands of the normal conducting RF cavities up-to-date transistor technology with increased power density has to be used. A 15 kW CW power ampifier prototype with the new technology has been developed by Sigma Phi Electronics and deliverd to KPH. In this paper we will present the results of the performance measurements of the amplifier.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF063

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF064

Beam Based Alignment of SRF Cavities in an Electron Injector Linac

linac, alignment, emittance, electron

4219

F. Hug
KPH, Mainz, Germany
M. Arnold, T. Bahlo, J. Pforr, N. Pietralla
TU Darmstadt, Darmstadt, Germany

Funding: Funded by DFG through Cluster of Excellence EXC 1098/2014 "PRISMA" and RTG 2128 "AccelencE" and by the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871
Proper alignment of accelerating cavities is an important issue concerning beam quality of accelerators. In particular SRF cavities of injector linacs using high accelerating gradients on low beta electron beams can affect the beam quality significantly when not aligned perfectly. On the other hand knowing the exact position of every cavity after several cool-down cycles of a cryomodule can be difficult depending on the cryomodule design. We will report on operational experience on the SC injector of the Darmstadt superconducting linac and ERL (S-DALINAC) showing unexpected effects on beam dynamics and beam quality. Operators could observe transverse beam deflections by changing accelerating phases of the injector SRF-cavities while a growth of tranverse emittance occurred at the same time. As beam currents in the S-DALINAC injector do never exceed 100 μA and the effects could even be observed at nA beam currents space-charge effects could be eliminated to be the reason for these observations. In this work we will report on the possibility to align SRF cavities after cooldown by measuring the transverse deflection of the beam and compare results with beam dynamics simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF064

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF089

Design of a Radial RF Electron Gun

gun, electron, cathode, target

4287

J.W. Lewellen, F.L. Krawczyk
LANL, Los Alamos, New Mexico, USA
J.R. Harris
Directed Energy Directorate, Air Force Research Laboratory, Albuquerque, USA

Funding: DOE Accelerator Stewardship Program
Most electron beam sources generate beams that propagate away from the source in a single primary direction, with the overall envelope being either pencil-like or sheet-like. We present the design of a radial RF electron gun, intended to produce a radially propagating electron beam (either towards or away from an axis) with the overall envelope being that of an expanding or contracting annulus. Such a source has several potential advantages for materials processing, and may also be useful as the basis for unique optical elements for hadron machines.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF089

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF090

Linac Design Elements for Spaceborne Accelerators

linac, operation, electron, dipole

4291

J.W. Lewellen, C.E. Buechler, G.E. Dale, M.A. Holloway, D.C. Nguyen, D. Patrick
LANL, Los Alamos, New Mexico, USA
V.A. Dolgashev, E.N. Jongewaard, J. Neilson, S.G. Tantawi
SLAC, Menlo Park, California, USA
J-.M. Lauenstein
NASA Goddard Space Flight Center, Greenbelt, USA

Funding: Los Alamos National Laboratory LDRD and Program Development
Los Alamos National Laboratory, in collaboration with SLAC and Goddard Space Flight Center, have begun developing a high-duty-factor, MeV-range linear accelerator intended for use on satellites, specifically to probe the magnetosphere-ionosphere linkage. The design makes use of low-beta C-band cavities operating at moderate gradients, individually powered by 500-W RF amplifier chips. We present the current state of the design, and technology maturation efforts including RF amplifier performance studies, cavity tuner design and an initial acceleration test using a DC beam source and single RF cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF090

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK004

Pulse-Picking by Resonant Excitation (PPRE) for Timing Users at the MAX IV 3 GeV Storage Ring

emittance, photon, simulation, storage-ring

4300

T. Olsson, Å. Andersson, D.K. Olsson
MAX IV Laboratory, Lund University, Lund, Sweden

At synchrotron light storage rings there is demand for serving both high-brilliance and timing users simultaneously. At many rings this is commonly achieved by operating fill patterns with gaps of sufficient length, but this is not favorable for rings that operate with passive harmonic cavities to damp instabilities and increase Touschek lifetime by lengthening the bunches. For such rings, gaps in the fill pattern could severely reduce the achievable bunch lengths. For the MAX IV 3 GeV storage ring, sufficient bunch lengthening is also essential for conserving the ultralow emittance and reducing heat load on vacuum components at high current. It is therefore of interest to study methods to serve timing users while operating without gap in the fill pattern. Once such method is PPRE, where the transverse emittance of one bunch in the bunch train is increased by an incoherent betatron excitation. This paper presents simulations for the MAX IV 3 GeV storage ring and discusses the machine requirements as well as the achievable performance for timing users.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK004

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK043

Timing Stability at LCLS

timing, laser, linac, FEL

4381

F.-J. Decker, R.N. Coffee, W.S. Colocho, J.M. Glownia, K. Gumerlock, B.L. Hill, T.J. Maxwell, J. May
SLAC, Menlo Park, California, USA

The beam stability of the LCLS (Linac Coherent Light Source) has increased substantially over the years. Transversely it is a fraction of the beam size. The energy jitter was reduced from five times the energy spread to a fraction of it. Only the timing jitter is left. It got improved during the energy jitter reduction, but typically left alone. So we have five dimensions of the six-dimensional phase space covered with feedbacks and special 60-Hz jitter setups which eliminate the difference between every other pulse, but not for the general timing setup. We describe a scheme with the RF of the XTCAV, which could be used for other setups like lasers.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK043

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK048

The Design and Construction of a Novel Dual-Mode Dual-Frequency Linac Design

operation, impedance, resonance, acceleration

4391

M.H. Nasr, S.G. Tantawi
SLAC, Menlo Park, California, USA

One promising approach in boosting accelerators efficiency is dual-mode simultaneous operation. In our work, the topic of dual-mode acceleration is studied from a wider perspective with new approaches and tools. We present a new type of accelerator structures that operates simultaneously with two modes and two frequencies. The frequencies are not constrained to be harmonically related, but rather have a common sub-harmonic. These designs will utilize a newly developed parallel-feeding network that feeds each individual accelerating cell independently using a distributed feeding network. As a result, the design problem converges to a single-cell design with identical cells. The cells are designed for maximum efficiency using new geometrical optimization that utilizes nonuniform rational B-spline (NURBS) with a series of control points. We will present a study on the topic for S-band simultaneous operation with C-band or X-band.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK048

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK049

New Geometrical-Optimization Approach using Splines for Enhanced Accelerator Cavities' Performance

controls, impedance, simulation, accelerating-gradient

4395

M.H. Nasr, S.G. Tantawi
SLAC, Menlo Park, California, USA

Over the past decades accelerator scientists made a huge effort in advancing the technology of particle accelerators, which lead to state-of-the-art fabrication techniques as well as simulation tools. Combining these advancements with the large boosting in computing speed provides large flexibility and motivation to investigate new accelerator geometries. In this paper, we describe a new optimization approach for the geometry of accelerating cells. This approach uses a set of control points with variable positions to control a non-uniform rational B-spline (NURBS), which describes the cavity shape. The positions of the control points are then optimized using differential-evolution optimization to maximize/minimize a defined optimization function, which is defined by the user and depends on the cavity parameters such as the shunt impedance, wall losses, peak surface fields…etc. This optimization approach leads to accelerator geometries with enhanced performance and very smooth surface fields.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK049

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK059

Commissioning of Front End of CLARA Facility at Daresbury Laboratory

cathode, gun, controls, MMI

4426

D. Angal-Kalinin, A.D. Brynes, R.K. Buckley, S.R. Buckley, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, S.A. Griffiths, F. Jackson, S.P. Jamison, J.K. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, T.C.Q. Noakes, T.J. Price, M.D. Roper, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, E.W. Snedden, N. Thompson, C. Tollervey, R. Valizadeh, D.A. Walsh, T.M. Weston, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A.D. Brynes, J.A. Clarke, L.S. Cowie, K.D. Dumbell, D.J. Dunning, P. Goudket, F. Jackson, S.P. Jamison, J.K. Jones, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R.J. Cash, R.F. Clarke, G. Cox, G.P. Diakun, A. Gallagher, K.D. Gleave, M.D. Hancock, J.P. Hindley, C. Hodgkinson, A. Oates, J.T.G. Wilson
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

CLARA (Compact Linear Accelerator for Research and Applications) is a Free Electron Laser (FEL) test facility being developed at STFC Daresbury Laboratory. The principal aim of CLARA is to test advanced FEL schemes which can later be implemented on existing and future short wavelength FELs. The installation of the Front End (FE) section of CLARA, a S-bend merging with existing VELA (Versatile Electron Linear Accelerator) beam line and installation of a high repetition rate RF gun on VELA was completed in 2017. First beam commissioning results and high level software developments are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK059

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK072

X-Band RF System as Linearizer for SXFEL

FEL, laser, electron, free-electron-laser

4467

J.H. Tan, W. Fang, Q. Gu, X.X. Huang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

High gradient accelerating structure is the core technology of compact linear collider facilities and compact free electron laser facilities. Meanwhile the important limitation of improving brightness in free electron laser facility is the non-linear energy spread, and the X-band accelerating structure can provide harmonic compensation in linac to linearize the bunch compression process. In this paper, a special X-band traveling-wave accelerating structure is primary designed for compact hard x-ray free electron laser facility. Then the structure is processed manufacturing, and realize high power experiment and linear bunch compression at Shanghai soft x-ray free electron laser facility.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK072

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK084

E-field Measurement of 9.3 GHz RF cavity for 6 MeV LINAC

linac, electromagnetic-fields, electron, hardware

4496

D.H. Ha, J.-S. Chai, M. Ghergherehchi, H.S. Kim, J.C. Lee, H. Namgoong, J.H. Seo, Shin, S.W. Shin
SKKU, Suwon, Republic of Korea

In order to achieve performance close to the design value, fabricated cavity was tuned at Sunkyunkwan university. Tuning was done in two step: each cell tuning and bead-pull system. Each cell tuning was used to determine the status of each cell and to remove the stop-band. Bead-pull system was used to measure the E-field distribution and obtain the required field flatness. This paper describes each cell measurement data and bead-pull measurement system and data.
x-band, linac, measurement

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK084

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK085

Development of a Pre-Injector Test Bench for Future SLRI Light Source

electron, gun, emittance, cathode

4499

K. Kittimanapun, Ch. Dhammatong, N. Juntong, W. Phacheerak, M. Phanak
SLRI, Nakhon Ratchasima, Thailand

A pre-injector test bench at the Synchrotron Light Research Institute (SLRI) is under development as one of the preparations for the future SLRI light source and of choices for the possible upgrade of the current injector. The pre-injector test bench includes a pulsed thermionic gun, a fast pulse deflector, a buncher and a pre-buncher. The thermionic electron gun with a cathode made of a single crystal CeB6 is employed as an electron emitter providing small emittance and uniform electron density. The fast pulse deflector shorten the extracted electrons of a few microseconds to that of a few nanoseconds. The electron pulses are further bunched by both the 238 MHz pre-buncher and the 476 MHz buncher to allow the 1-MeV electron beam. The experimental setups for emittance and beam profile measurements are installed on a movable diagnostic stand which is, later on, replaced by the beam bunching devices. The designs of the test bench will be discussed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK085

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK087

Conceptual Design of the RF System for the Storage Ring and Linac of the New Light Source in Thailand

storage-ring, linac, acceleration, operation

4505

N. Juntong, T. Chanwattana, K. Kittimanapun, T. Pulampong, P. Sunwong
SLRI, Nakhon Ratchasima, Thailand

The new light source facility in Thailand will be a ring-based light source with the circumference of approximately 300m and an electron energy of 3GeV. The target beam emittance is below 1.0 nm·rad with a maximum beam current of 300mA. The injector utilizes a full energy C-band linac with a photocathode RF electron gun. The storage ring RF system is based on a 500MHz frequency. The EU-HOM damped cavity and the new SPring-8 design TM020 cavity is the choice of the storage ring cavity. The RF power unit for storage ring can either be a high-power klystron feeding all RF cavities or a combination of low power IOTs or solid-state amplifiers feeding each cavity. The high gradient C-band structure is considered as the main accelerating structure for linac. The RF power system for linac will base on klystron and a modular modulator. Details of RF systems options for this new light source project will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK087

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK090

First RF Test Results of Two-Cavities Accelerating Cryomodule for ARIEL eLinac at TRIUMF

cryomodule, linac, TRIUMF, pick-up

4512

Y. Ma, Z.T. Ang, K. Fong, J.J. Keir, D. Kishi, D. Lang, R.E. Laxdal, R.R. Nagimov, B.S. Waraich, Z.Y. Yao, V. Zvyagintsev
TRIUMF, Vancouver, Canada

The Advanced Rare Isotope Laboratory (ARIEL) pro-ject requires a 50 MeV, 10 mA continuous-wave (CW) electron linear accelerator (e-Linac) as a driver accelera-tor. Now the stage of the 30MeV portion of the e-Linac is under commissioning which includes an injector cry-omodule(ICM) and the 1st accelerator cryomodules (ACM1) with two cavities configuration. A single 290kW klystron is used to feed the two ACM1 cavities in vector sum closed-loop control. In this paper the initial commis-sioning results of the ACM1 RF system will be present.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK090

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK096

Tuners Alignment on Two 9-Cell Cavities with Single Amplifier under Self-Excited Loop

TRIUMF, detector, linac, cryomodule

4527

K. Fong, Z.T. Ang, M.P. Laverty, Q. Zheng
TRIUMF, Vancouver, Canada

The TRIUMF eLinac ACM consists of two 9-cell cavities which are driven by a single klystron. The output power from the klystron are split by a variable power divider and send down 2 independently phase adjustable transmission lines to their respective cryomodules. The vector sum of the fields from both cryomodules is used for phase-locked self-excited loop regulation. A semi-automatic procedure to tune the 2 cyromodules to provide the correct amplitudes and phases for self-excitation as well as beam acceleration is described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK096

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK097

First Conceptual Design Studies of an Electron Source for Ultrafast Electron Diffraction at DELTA

electron, laser, space-charge, gun

4530

D. Krieg, S. Khan
DELTA, Dortmund, Germany
K. Sokolowski-Tinten
Universität Duisburg-Essen, Duisburg, Germany

Funding: MERCUR Pr-2017-0002
Ultrafast electron diffraction (UED) is a technique to study the structural dynamics of matter, combining diffraction of electrons with sub-angstrom De-Broglie wavelength with femtosecond time resolution. The method is complementary to X-ray scattering at free-electron lasers. UED pump-probe experiments require ultrashort laser pulses to pump a sample, electron bunches with small emittance and ultrashort length to analyze the state of the sample by diffraction, as well as excellent control of the delay between them. While most UED systems are based on electrostatic electron sources in the keV regime, electrons accelerated to a few MeV in a radiofrequency photocathode gun offer significant advantages regarding emittance and bunch length due to the reduction of space charge effects. Furthermore, the longer mean free path of MeV electrons allows for thicker samples and hence a broader range of possible materials. In this paper, a first conceptual design and simulation results for a university-based UED facility with ultrashort and low-emittance MeV electron bunches are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK097

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK107

Design of a High Charge, Low Energy, Magnetized Electron Injector

electron, emittance, solenoid, cathode

4564

F.E. Hannon
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Simulations of a magnetized injector for the bunched-beam electron cooler ring, as part of the Jefferson Lab Electron Ion Collider (JLEIC) are presented. A challenge of such an injector is in generating a magnetized, 3.2nC electron bunch at low energy and preserving the angular momentum so it can subsequently be merged into the cooler ring and transported to the cooling solenoid without degradation. The design of the proposed injector and the effect it has on the beam are discussed in detail.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK107

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK115

Optical Cavity R&D for Laser-Electron Interaction Applications

laser, HOM, electron, experiment

4587

X. Liu, W.-H. Huang, C.-X. Tang, L.X. Yan
TUB, Beijing, People's Republic of China
R. Chiche, K. Dupraz, P. Favier, A. Martens, H. Monard, Z.F. Zomer
LAL, Orsay, France
D. Nutarelli
LAC, Orsay, France

Laser-electron Inverse Compton Scattering X-ray source based on optical enhancement cavity is expected to produce higher-flux and better-quality X-rays than conventional sources, in addition, to become more compact, much cheaper than Free Electron Laser and Synchrotron Radiation. One X-ray source named ThomX is under construction at LAL, France. An electron storage ring with 50 MeV, 16.7 MHz electron beam will collide with a few picosecond pulsed laser to produce 10¹³ photons per second. A prototype cavity with a high finesse (F=25,100) in the picosecond regime is used to perform R & D for ThomX. We obtained 380 kW power stored in the optical cavity and mode instabilities were observed. The EOM-based frequency modulation to measure the finesse, the influence of dust on finesse, high-power experiments and other related issues are mentioned briefly. We will also describe the TTX2 (Tsinghua Thomson Scattering X-ray source) at Tsinghua University which is in design process. TTX2 prefers using an electron storage ring and an optical cavity in order to get high X-ray flux.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK115

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK130

Study of Beam Instabilities with a Higher-Harmonic Cavity for the HALS

coupling, storage-ring, HOM, quadrupole

4623

Y.G. Tang, W. Li, Z.B. Sun, L. Wang, C.-F. Wu
USTC/NSRL, Hefei, Anhui, People's Republic of China

Hefei Advanced Light Source (HALS), a diffrac-tion-limited storage ring is on the design. In HALS project, a passive higher-harmonic cavity may be added in order to increase the beam lifetime of the storage ring. When the storage ring is operated with a small momentum compaction, instabilities limit the utility of the high-er-harmonic cavity. In this paper, we run an algorithm (analytic modeling) to consider the Robinson instabilities for normal and superconducting cavity respectively. The Robinson instabilities are predicted with and without mode coupling. Coupled-bunch instability induced by resonant interaction with parasitic longitudinal mode is also considered. The analytic modeling may be used to give rf-cavity parameters that are more conducive to stability. The results show that the storage ring can oper-ate at a higher beam current and the parasitic high-er-order mode of the fundamental cavity has less impact on the beam by using superconducting harmonic cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK130

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMK148

Design Study on Linac-bsed Laser-cmpton Scattering X-Ray Source

laser, electron, linac, photon

4651

K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M.K. Fukuda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
Y. Koshiba
RISE, Tokyo, Japan
M. Washio
Waseda University, Tokyo, Japan

We have been developing a laser-Compton scattering X-ray source using multi-bunch linac and optical enhancement cavity. This combination have a possibility to realize a high brightness compact X-ray source. A key issue of the system is around interaction point. Compatibility of electron focusing, optical cavity and X-ray path is difficult in the current setup. Thus we propose to use rf transverse deflecting cavity for crab crossing of laser and electron. In this conference, design study of the whole laser-Compton X-ray source consist of electron linac and optical enhancement cavity will be reported. The system configuration, resulting flux and brightness, and its applications will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK148

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML006

Using Drive Rods in Inductions Cells to Reduce the Beam Break Up Instability

impedance, simulation, induction, wakefield

4658

N. Pogue, T.L. Houck, B.R. Poole
LLNL, Livermore, California, USA

The Beam Breakup Instability is a critical effect to reduce in high current induction accelerators. The RF modes generated inside the induction cells can deflect or degrade subsequent beam traversing the cell. Significant effort has been invested in minimizing the effect over several decades. One mechanism that is known to reduce the transverse impedance, the main observable experimentally which directly relates to the BBU amplitude, is to introduce ferrites to absorb the fields. Another, less investigated mechanism, is to disturb the modes symmetry by inserting the drive rods at the proper locations in the cell. This paper will show that the drive rods can dramatically reduce the transverse impedance, and will show that simulations are maturing towards predicting this effect. Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML006

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML015

Dielectric Multipactor Discharges at 110 GHz

multipactoring, experiment, GUI, vacuum

4684

S. C. Schaub
MIT, Cambridge, Massachusetts, USA
M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA

A 1.5 MW, 110 GHz gyrotron has been used to experimentally measure the maximum sustainable fields on dielectric materials in vacuum. The purpose of this work is to evaluate the suitability of these materials for future applications in high frequency linear accelerators and high power terahertz components. To our knowledge, these are the first measurements of multipactor phenomena in the millimeter wave or terahertz frequency range. Materials tested include alumina, sapphire, fused quartz, crystal quartz, and high resistivity silicon. Dielectric samples were tested both as windows, with electric fields parallel to the surface, and sub-wavelength dielectric rod waveguides, with electric fields perpendicular to the surface. Surface electric fields in excess of 52 MV/m were achieved in 3 microsecond pulses. Visible light emission, absorbed/scattered microwave power, and emitted electrons were measured to characterize the discharges on the dielectric surfaces. The results of these experiments have been compared to theoretical calculations of multipactor discharges, testing these theories at significantly higher frequencies than has been done before.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML032

Using Deep Reinforcement Learning for Designing Sub-Relativistic Electron Linac

network, electron, linac, acceleration

4720

Shin, S.W. Shin, J.-S. Chai, M. Ghergherehchi
SKKU, Suwon, Republic of Korea

Generally, when designing an accelerator device, the design is based on the experience and knowledge of the designer. Most of the design process proceeds by chang-ing the parameters and looking at the trends and then determining the optimal values. This process is time-consuming and tedious. In order to efficiently perform this tedious design process, a method using an optimization algorithm is used. Recently, many people started to get interested in the algorithm used in AlphaGo, which became famous when it won the professional Go player developed by google The algorithm used in AlphaGo is an algorithm called reinforcement learning that learns how to get optimal reward in various states by moving around a solution space that the agent has not told beforehand. In this paper, we will discuss about designing an particle accelerator by applying Deep Q-network algorithm which is one kind of deep learning reinforcement learning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML032

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML047

Design and Measurement of the X-Band Pulse Compressor for TTX

GUI, coupling, vacuum, ISOL

4745

Y.L. Jiang, H.B. Chen, C. Cheng, W. Gai, J. Shi, P. Wang, Z.H. Wang, X.W. Wu, H. Zha
TUB, Beijing, People's Republic of China

A radio frequency (RF) pulse compressor had been designed for the X-band (11.424 GHz) high power test stands at the Accelerator Laboratory of Tsinghua University. It is the SLED-I type pulse compressor, which uses a high quality factor corrugated circular cavity to store the RF power. An RF polarizer couples two quadrature modes into the cavity so that the pulse compressor needs only one cavity. The cavity implements HE1-1-14 mode, with the Q0 of 115, 000 and the coupling factor (β) of 3.23. The design and the microwave measurement before brazing of this pulse compressor are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML047

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML054

Design Studies of an S-Band Multipacting Electron Gun

electron, gun, cathode, operation

4759

C. Henkel, W. Hillert, V. Miltchev
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
K. Flöttmann
DESY, Hamburg, Germany

A multipacting electron gun (MEG) is a micro-pulse electron source based on secondary electron emission in a resonant microwave cavity structure for the generation of low emittance electron bunches with high repetition rate. By theoretical simulations a suitable radio-frequency gun design at 3 GHz is established, simultaneously meeting the demands of bunch production and amplification process as well as including the effects of space charge and beam loading for the evolution of a stable beam. In this contribution we show detailed simulation studies of the impact of important design parameters like mechanical dimensions and choice of material on the average output current, which is in the order of several mA. For the experimental investigation a test setup is under construction, which may demonstrate the application of MEG's as a serious alternative or addition to commonly used electron sources like thermionic and photocathodes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML054

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML061

X-Band Low Q Cavity Beam Position Monitor Study

FEL, simulation, electron, GUI

4777

S.S. Cao
SINAP, Shanghai, People's Republic of China
Y.B. Leng, R.X. Yuan
SSRF, Shanghai, People's Republic of China

The high repetition-rate and high peak brilliance of X-ray free-electron laser (XFEL) allow studying many scientific experiments that have not been feasible. To realize such high performance, a sub-micron beam transverse position measurement is required. The cavity-type beam position monitor (CBPM), as a non-destructive diagnostics tool with high potential in resolution performance, has been applied in different free electron laser facilities (FELs). In this research, an X-band high bandwidth CBPM has been studied and used for pre-research on bunch-by-bunch diagnostic for the pulsed FEL with high repetition-rate. Its bandwidth reaches 300 MHz. Design considerations and simulation results of the CBPM have been discussed and presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML061

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML063

Micro-Bunched Beam Production at FAST for Narrow Band THz Generation Using a Slit-Mask

electron, radiation, simulation, quadrupole

4784

J. Hyun
Sokendai, Ibaraki, Japan
D.J. Crawford, D.R. Edstrom, J. Ruan, J.K. Santucci, T. Sen, J.C.T. Thangaraj, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA

We discuss simulations and experiments on creating micro-bunch beams for generating narrow band THz radiation at the Fermilab Accelerator Science and Technology (FAST) facility. The low-energy electron beamline at FAST consists of a photoinjector-based RF gun, two L-band superconducting accelerating cavities, a chicane, and a beam dump. The electron bunches are lengthened with cavity phases set off-crest for better longitudinal separation and then micro-bunched with a slit-mask installed in the chicane. We carried out the experiments with 30 MeV electron beams and detected signals of the micro-bunching using a skew quadrupole magnet in the chicane. In this paper, the details of micro-bunch beam production, the detection of micro-bunching and comparison with simulations are described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML063

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML065

Preliminary Results of the Bunch Arrival-Time Monitor at SXFEL

electron, laser, pick-up, FEL

4787

J.G. Wang, B. Liu
SINAP, Shanghai, People's Republic of China

Based on an electro-optical intensity modulation detection scheme, a Bunch Arrival-time Monitor (BAM) is under study at Shanghai soft X-ray Free Electron Laser (SXFEL) to meet the high-resolution requirements of the measurement of bunch arrival time. The first BAM is installed and is being tested at the SXFEL upstream of the first short undulator (modulator) near the seed laser injection point. In this paper, we present the basic working principle, the design of the BAM system and report the preliminary test results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML065

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML071

Upgrade of Digital BPM Processor at DCLS and SXFEL

FEL, software, EPICS, FPGA

4807

L.W. Lai, F.Z. Chen, Y.B. Leng, T. Wu, Y.B. Yan
SSRF, Shanghai, People's Republic of China
J. Chen
SINAP, Shanghai, People's Republic of China

A digital BPM processor has been developed at 2016 in SINAP for DCLS and SXFEL, which are FEL facilities built in China. The stripline BPM and cavity BPM processors share the same hardware platform and firmware, but the processing algorithms implemented in EPICS IOC on the ARM CPU are different. The capability of the ARM limits the processing speed to 10 bunches per second. Now the bunch rate of DCLS and SXFEL are going to increase from 10Hz to 50Hz. To meet the higher processing speed requirements, the processor firmware and software are upgraded in 2017. All BPM signal processing algorithms are implemented in FPGA, and EPICS IOC reads results only. After the upgrade, the processing speed reach 120 bunches per second. And this is also a good preparation for future Shanghai Hard-X ray FEL, which bunch rate is about 1MHz.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML071

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML081

Beam-Based Measurements of the ISAC-II Superconducting Heavy Ion Linac

linac, ISAC, alignment, TRIUMF

4841

S. Kiy, R.E. Laxdal, M. Marchetto, S.D. Rädel, O. Shelbaya
TRIUMF, Vancouver, Canada

Preparation for experiments, which typically run for one to two weeks in the ISAC-II facility at TRIUMF, requires some amount of overhead, limiting the efficiency of the facility. Efforts are underway to improve the ISAC-II linac model to reduce this overhead while also improving the quality of the delivered ion beam. This can be accomplished with beam-based measurements and corrections of alignment, cavity gradients, focal strengths, and more. A review of the present state of the linac will be given, including measured mis-alignments and other factors that affect the reproducibility of tunes. The outlook on expected improvements will also be summarized, including progress on the automatic phasing of cavities with a focus on integration to the High Level Application platform being developed at TRIUMF. Lastly, a summary will be given on the expected paradigm shift in the tuning approach taken: moving from re-active tuning by operators or beam delivery experts to pro-active measurements and investigations, version-controlled tunes, and continuous feedback from beam physicists.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML081

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML082

Reflected Power Based Extremum Seeking Control Algorithm to Tune the Resonance Frequency of Room Temperature Cavities

controls, resonance, TRIUMF, ISAC

4844

R. Leewe, K. Fong, Z. Shahriari
TRIUMF, Vancouver, Canada
M. Moallem
SFU, Surrey, Canada

A sliding mode extremum seeking algorithm to tune the resonance frequency was implemented in two of TRIUMF's DTL tanks. The tuning algorithm searches for the minimum reflected power point and was developed to eliminate the highly temperature dependent phase measurement, which was previously used to tune the resonance frequency. Short and long term measurement results show that the tuning algorithm compensates for the RF heating effect as well as for diurnal temperature variations. Reflected power measurements of TRIUMF's DTL tank 3 were taken for both cases of operating the phase based tuning system and the reflected power based tuning system, with an outcome of a higher tuning accuracy of the newly developed system. Another advantage is a quick cavity start up time, as the reflected power based system does not rely on a reference set point which has do be adjusted manually. The sliding mode extremum seeking control loop is currently commissioned in further room temperature cavities of the TRIUMF's ISAC I facility.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML082

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML083

Iterative Learning Control to Cancel Beam Loading Effect on Amplitude and Phase of the Accelerating Field

controls, beam-loading, feedback, simulation

4847

Z. Shahriari, K. Fong
TRIUMF, Vancouver, Canada
G. A. Dumont
UBC, Vancouver, Canada

Funding: This research is supported by TRIUMF through federal funding via a contribution agreement with the National Research Council of Canada.
Iterative learning control (ILC) is an open loop control strategy that improves the performance of a repetitive system through learning from previous iterations. ILC can be used to compensate for a repetitive disturbance like the beam loading effect in resonators. Assuming that the beam loading disturbance is identical for all iterations, the learning law can be non-causal; it can anticipate the disturbance and preemptively counteract its effect. In this work, we aim to use ILC to cancel beam loading effect on amplitude and phase. Feedback controllers are not fast enough for this purpose. A normal feed forward controller may not be sufficient as well if there is a difference between the feed forward signal and the beam loading current. Therefore, the goal is to use ILC to adaptively cancel the beam loading effect.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML083

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML088

Cavity Impedance Reduction Strategies During Multi Cavity Operation in the SIS100 High Intensity Hadron Synchrotron

controls, emittance, resonance, acceleration

4863

D. Mihailescu Stoica, D. Domont-Yankulova
Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
D. Domont-Yankulova, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
H. Klingbeil, D.E.M. Lens
GSI, Darmstadt, Germany

Funding: Supported by GSI Helmholtzzentrum für Schwerionenforschung GmbH
The planned SIS100 heavy ion synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung will possess twenty ferrite accelerating cavities in its final stage of extension. As at injection and at flat top during slow extraction of the planned acceleration cycles the RF voltage will be relatively low, not all cavities will be active in this part of operation. It is important to analyse the impact of the inactive cavities on the overall RF voltage and subsequently their implication on the longitudinal particle dynamics. Classical approaches for reducing the beam impedance consist of active detuning of the cavities to pre-described parking frequencies. The fact that two out of ten buckets have to stay empty in all SIS100 scenarios is of particular interest as additional frequency components appear in the excitatory beam current, which have to be considered when the cavity is detuned. Therefore multi-cavity particle tracking simulations, consisting of twenty cavities and their attached LLRF control systems, are carried out in order to analyse different possibilities to minimize the impact on the beam dynamics and emittance growth.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML088

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML092

Electromagnetic and Mechanical Design of High Gradient S-Band Accelerator in TTX

scattering, HOM, laser, linac

4876

D.Z. Cao, H.B. Chen, Y. C. Du, W. Gai, W.-H. Huang, J. Shi, C.-X. Tang, P. Wang, H. Zha
TUB, Beijing, People's Republic of China

Thomson scattering x-ray source is an essential scien-tific research tool in x-ray imaging technology for vari-ous fields. Upgrading plan of replacing the 3-meter S-band linac with a shorter structure operating at higher gradient in Tsinghua Thomson scattering X-ray source (TTX) is undergoing so far, aiming to enhance the accel-erating gradient from 15 MV/m to 30 MV/m. Detailed parameters of couplers and mechanical design of acceler-ation structure are presented in this work.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML092

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML094

New Methods for Dispersion Measurement and Correction for 12 GeV CEBAF

quadrupole, software, controls, simulation

4882

D.L. Turner
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
This paper discusses methods for dispersion measurement and correction for the Continuous Electron Beam Accelerator Facility (CEBAF) for the 12GeV era. New methods will be compared with methods used during the 6GeV era. New software tools which implement the new methods will be discussed, along with a method for automating dispersion measurement and correction. New dispersion measurement and correction methods and tools are being implemented to provide more deterministic results and to reduce machine setup time.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML094

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML095

Improvement of Wire-Stretching Technique to the RF Measurements of E-Center and Multipole Field for the Dipole Cavities

kicker, coupling, simulation, electron

4885

G.-T. Park, J. Guo, H. Wang
JLab, Newport News, Virginia, USA
A. Overstreet
ODU, Norfolk, Virginia, USA
B. P. Xiao, T. Xin
BNL, Upton, Long Island, New York, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
After the first publication* of wire-stretching technique from its principle to measure the electrical center of a deflecting cavity, more refinements of this techniques including the review of its analytical and simulation results, RF circuit improvement to improve the signal to noise ratio and its application to other cavities have been developed. These applications include the electrical center measurements for the LHC RFD and DQW crabbing cavity prototypes, multi-frequency harmonic kicker cavity for JLEIC electron cooler**, TE011 cavity developed for the beam magnetization measurement***, and a separator cavity at BNL****. Further development of measurement calibration, error reduction, alignment of cavity installation to the machine beam line, and multipole field analysis for the beam dynamics will be presented.
*H. Wang, Proceedings of NAPAC2016, pp225-228
**S. A. Overstreet, BS Thesis 2017, Guilford College, Greensboro, NC
***J. Guo et al. these proceedings
****T. Xin et al, these proceedings

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML095

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML096

A Non-Invasive Magnetic Momentum Monitor Using a TE011 Cavity

impedance, electron, GUI, coupling

4889

J. Guo, J. Henry, M. Poelker, R.A. Rimmer, R. Suleiman, H. Wang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC with Laboratory Directed Research and Development funding, under U.S. DOE Contract No. DE-AC05-06OR23177.
The Jefferson Lab Electron-Ion Collider (JLEIC) design relies on cooling of the ion beam with bunched electron beam. The bunched beam cooler complex consists of a high current magnetized electron source, an energy recovery linac, a circulating ring, and a pair of long solenoids where the cooling takes place. A non-invasive real time monitoring system is highly desired to quantify electron beam magnetization. The authors propose to use a passive copper RF cavity in TE011 mode as such a monitor. In this paper, we will show the mechanism and scaling law of this device, as well as the design and testing results of the prototype cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML096

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML099

Phase Extraction and Stabilization for Coherent Pulse Stacking

controls, laser, FPGA, feedback

4895

Y.L. Xu, W.-H. Huang, C.-X. Tang, L.X. Yan
TUB, Beijing, People's Republic of China
L.R. Doolittle, Q. Du, G. Huang, W. Leemans, D. Li, R.B. Wilcox, Y. Yang, T. Zhou
LBNL, Berkeley, California, USA
A. Galvanauskas
University of Michigan, Ann Arbor, Michigan, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Contract DE-AC02-05CH11231.
Coherent pulse stacking (CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy and high average power. We model the CPS as a digital filter in the Z domain, and implement two deterministic algorithms extracting the cavity phase from limited data where only the pulse intensity is available. In a 2-stage 15-pulse CPS system, each optical cavity is stabilized at an individually-prescribed round-trip phase with 0.7 deg and 2.1 deg RMS phase errors for Stage 1 and Stage 2 respectively. Optical cavity phase control with nm accuracy ensures 1.2% intensity stability of the stacked pulse over 12 hours.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML099

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML113

Design and Simulation of the Waveguide Coupler for the Cavity Beam Monitor

GUI, simulation, coupling, electromagnetic-fields

4932

Q. Wang, Q. Luo, B.G. Sun, F.F. Wu, Y.L. Yang, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China
Y.W. Wu
USTC, Hefei, Anhui, People's Republic of China

Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900), NSFC (11375178, 11575181) and the Fundamental Research Funds for the Central Universities (WK2310000046)
The waveguide coupling is an important way to extract the signals of the specific eigenmodes required. The design of the waveguide coupler, including the waveguide-to-coaxial adapter behind it for the cavity bunch length monitor is presented. The influence of the dimension parameters is analyzed, which offers the theoretical support for the design and application of cavity bunch length monitor or cavity beam position monitor (CBPM). A series simulation based on CST is performed to verify the feasibility, and the simulation results show good performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML113

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML119

A Time-of-Flight Based Energy Measurement System for the LIGHT Medical Accelerator

MMI, rfq, proton, linac

4951

F. Galizzi
University of Bergamo, Bergamo, Italy
M. Caldara, F. Galizzi, A. Jeff
A.D.A.M. SA, Meyrin, Switzerland

The LIGHT proton therapy facility is the first compact Linac that will deliver proton beams up to 230 MeV for cancer treatment. The proton beam is pulsed; pulses repetition rate can reach 200 Hz. LIGHT prototype is currently being commissioned by AVO/ADAM at CERN, while the first full installation is foreseen in 2019. Beam energy translates directly to range penetration in the body, so it is of the utmost importance to monitor it accurately especially for Linacs, since each beam pulse is directly transported to the patient. We present the implementation of a non-interceptive beam energy measurement system based on the Time-of-Flight technique. Unlike state of the art ToF systems this one has been designed to measure autonomously the mean energy of the beam with medical resolution (0.03 %) by processing as little as 1 us of data providing the result within 1 to 2 ms over an energy range from 5 to 230 MeV. The first results for beams up to 7.5 MeV are shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML119

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML120

Development of Coating Technique for Superconducting Multilayered Structure

site, target, experiment, acceleration

4954

R. Ito, T. Nagata
ULVAC, Inc, Chiba, Japan
H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
H. Ito
Sokendai, Ibaraki, Japan
Y. Iwashita, R. Katayama
Kyoto ICR, Uji, Kyoto, Japan
H. Oikawa
Utsunomiya University, Utsunomiya, Japan

In order to increase the maximum acceleration gradient of SRF cavities, S-I-S (superconductor-insulator-superconductor) multilayered structure theory has been proposed. We focused on NbN which has a higher superconducting transition temperature than Nb. Firstly, we researched the optimal deposition condition for N2 gas reactive sputtering of NbN by using in-house inter-back type DC magnetron sputtering equipment. The critical condition for a thin film with strong crystalline orientation of NbN was identified. The superconducting transition temperature of the NbN thin film, which were coated under the best condition, was over 14 K. Secondly, we tried making S-I-S multilayered samples that was composed of NbN/SiO2/Nb substrate. The coating condition for the NbN layer was determined based on the research results in a single layer. The SiO2 layer was deposited with a film thickness of 30 nm that was theoretically expected to be effective as barrier layer. We applied O2 gas reactive AC magnetron sputtering for coating. In this article, the detailed results of the NbN single layer and multilayer film depositions are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML120

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML121

Compensation of Transient Beam Loading in Ramping Synchrotrons Using a Fixed Frequency Processing Clock

FPGA, feedback, LLRF, synchrotron

4957

F.J. Galindo Guarch, J.M.M.A. Moreno Arostegui
Universitat Politécnica de Catalunya, Barcelona, Spain
P. Baudrenghien, F.J. Galindo Guarch
CERN, Geneva, Switzerland

Transient beam loading compensation schemes, such as One-Turn-FeedBack (OTFB), require beam synchronous processing (BSP). Swept clocks derived from the RF, and therefore harmonic to the revolution frequency, are widely used in CERN synchrotrons; this simplifies implementation with energy ramping, where the revolution frequency changes. It is however not optimal for state-of-the-art digital hardware that prefers fixed frequency clocks. An alternative to the swept clocking is the use of a deterministic protocol, for example, White Rabbit (WR): a fixed reference clock can be extracted from its data stream, while enabling digital distribution of the RF frequency among other data. New algorithms must be developed for BSP using this fixed clock and the digital data transmitted on the WR link. This is the strategy adopted for the SPS Low Level RF (LLRF) upgrade. The paper gives an overview of the technical, technological and historical motivations for such a paradigm evolution. It lists the problems of fixed clock BSP, and presents an innovative solution based on a real-time variable ratio re-sampler for implementing an OTFB with the new fixed clock scheme.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML121

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML122

Beta-SRF - A New Facility to Characterize SRF Materials near Fundamental Limits

SRF, TRIUMF, linac, accelerating-gradient

4961

E. Thoeng
UBC & TRIUMF, Vancouver, British Columbia, Canada
R.A. Baartman, R.E. Laxdal, B. Matheson, G. Morris, N. Muller, S. Saminathan
TRIUMF, Vancouver, Canada
A. Chen
UBC, Vancouver, Canada
T. Junginger
Lancaster University, Lancaster, United Kingdom

Funding: Natural Sciences and Engineering Research Council of Canada (NSERC) & UBC (NSERC) IsoSiM Program
Demands of CW high-power LINAC require SRF cavities operating at the frontier of high accelerating gradient and low RF power dissipation, i.e. high quality factor (Q₀). This requirement poses a challenge for standard surface treatment recipes of SRF cavities. In a recent breakthrough, elliptical SRF cavities doped with Nitrogen have been shown to improve Q₀ by a factor of 3, close to the fundamental SRF limit. The fundamental mechanisms at microscopic level and optimum doping recipe, however, have still not fully been understood. Materials other than Nb have also been proposed for SRF cavities to overcome the fundamental limit already reached with Nitrogen doping, e.g. Nb₃Sn, MgB₂, and Nb-SIS multilayer. At TRIUMF, a unique experimental facility is currently being developed to address these issues. This facility will be able to probe local surface magnetic field in the order of the London Penetration Depth (several tens of nm) via \beta decay detection of a low-energy radioactive ion-beam. This allows depth-resolution and layer-by-layer measurement of magnetic field shielding effectiveness of different SRF materials at high-parallel field (up to 200 mT). Design and current development of this facility will be presented here, as well as commissioning and future measurements strategies for new SRF materials.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML122

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML123

The ESR Barrier-Bucket LLRF System - Design and First Results

LLRF, controls, experiment, synchrotron

4964

J. Harzheim, D. Domont-Yankulova, K. Groß, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
M. Frey, H. Klingbeil, D.E.M. Lens
GSI, Darmstadt, Germany

At GSI, Darmstadt, Germany, a Barrier-Bucket (BB) RF System is currently under development for the Experimental Storage Ring (ESR). The system consists of two broadband RF cavities, each driven by a solid state amplifier, with the purpose to produce two voltage pulses per beam revolution. This will enable highly sophisticated longitudinal beam manipulations like longitudinal capture, compression and decompression or stacking of the beam. For the LLRF System, several requirements have to be fulfilled. Besides high standards concerning the pulsed gap signal quality (e.g. ringing <2.5%), the system has to provide the flexibility for adiabatic voltage ramp-up and adiabatic pulse shifting with high timing accuracy. A connection to the FAIR Central Control System (CCS) is necessary, as amplitude and phase ramp data will be provided by the CCS. In this contribution, the structure of the ESR BB LLRF system is presented together with experimental results from the first version of the system, which will be installed in the ESR in March 2018.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML123

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML126

Design of High Efficiency High Power CW Linacs for Environmental and Industrial Applications

linac, simulation, solenoid, focusing

4974

M. Shumail, V.A. Dolgashev, C.M. Markusen
SLAC, Menlo Park, California, USA

Funding: US Department of Energy, Office of High Energy Physics, through Accelerator Stewardship Grant
We have used our accelerator design toolbox equations to design three high efficiency and high power CW accelerators for the environmental and medical applications. These are: 2MeV-1MW, 10MeV-10MW, and 10MeV-1MW linacs. These are all 10 m long, 1.3 GHz, π-mode standing wave structures with design efficiencies of 96.8, 97.4 and 86.5 %, and optimal coupling coefficients of 32.9, 43.5, and 7.45, respectively. We present the detailed design parameters of these linacs. The study of single-bunch beam breakup for these linacs and the simulations results from ABCI are also included. The initial cavities are optimized according to the speed of the electron bunch to maximize the shunt impedance. The plots of peak surface fields on these cavities are also presented. We have also included a detailed thermal analysis of these linacs. Finally, we present the results of ASTRA simulations of the three linacs with magnetic focusing. We have also included the complete design of rf-distributed-coupling manifold for the third linac along with the HFSS® simulation results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML126

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML132

Cryogenic Performance of an SRF Deflecting Cavity Fabricated Using Alternative Techniques for the ARIEL eLinac

SRF, linac, niobium, cryogenics

4992

D.W. Storey
Victoria University, Victoria, B.C., Canada
R.E. Laxdal, Z.Y. Yao
TRIUMF, Vancouver, Canada

A 650 MHz SRF deflecting mode cavity has been built and tested for use as a three-way beam separator in the ARIEL eLinac. The cavity operates in a TE-like mode, and has been optimized for high shunt impedance with minimal longitudinal footprint. The device is the first SRF cavity to be fully fabricated in house at TRIUMF. The requirements of the cavity allowed for the development of low cost manufacturing techniques, including the use of Reactor grade niobium and atmospheric pressure TIG welding. The cavity has been fabricated and tested at 4 K and 2 K, obtaining a 4 K Qo of 4·10⁸ at the operating voltage of 0.3 MV, surpassing the goal voltage and quality factor required for operation. Results of the cryogenic tests of the cavity will be presented here.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML132

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)