IPAC2018 - List of Keywords (operation)

Paper	Title	Other Keywords	Page
MOYGB1	Status and Future Strategy for Advanced High Power Microwave Sources for Accelerators	klystron, electron, cavity, 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
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MOZGBD3	Performance of the First LCLS-II Cryomodules: Issues and Solutions	cavity, cryomodule, HOM, radiation	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
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MOZGBE4	Overview of Fabrication Techniques and Lessons Learned with Accelerator Vacuum Windows	vacuum, Windows, target, site	51
	C.R. Ader, M.W. McGee, L.E. Nobrega, E.A. Voirin Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy. Vacuum thin windows have been used in Fermilab's accelerators for decades and typically have been overlooked in terms of their criticality and fragility. Vacuum windows allow beam to pass through while creating a boundary between vacuum and air or high vacuum and low vacuum areas. The design of vacuum windows, including titanium and beryllium windows, will be discussed as well as fabrication, testing, and operational concerns. Failure of windows will be reviewed as well as safety approaches to mitigating failures and extending the lifetimes of vacuum windows. Various methods of calculating the strengths of vacuum windows will be explored, including FEA.
	Slides MOZGBE4 [2.155 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE4
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MOZGBF1	FRIB Front End Construction and Commissioning	rfq, MMI, ECR, ion-source	58
	G. Pozdeyev FRIB, East Lansing, Michigan, USA
	The Facility for Rare Isotope Beams (FRIB) is based upon the CW, SC driver linac to accelerate all the stable isotopes up to more than 200 MeV/u with a beam power of 400 kW. The front end (FE) commissioning shall start in 2017. This invited talk presents the FRIB front end design, and current status of FRIB front end commissioning, including beam properties and energy, and their relationship to FRIB operational requirements.
	Slides MOZGBF1 [2.965 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF1
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MOZGBF4	Evolution of the Superconducting Linac Output Energy at the Spallation Neutron Source	cavity, cryomodule, 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
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MOPMF036	FCC-ee Hybrid RF Scheme	cavity, HOM, impedance, 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
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MOPMF040	Crossing Angle Anti-Leveling at the LHC in 2017	luminosity, proton, simulation, experiment	184
	N. Karastathis, K. Fuchsberger, M. Hostettler, Y. Papaphilippou, D. Pellegrini CERN, Geneva, Switzerland
	In 2017, LHC incorporated in operation an anti-leveling procedure of adapting in steps the crossing angle of the colliding beams to increase the integrated luminosity. In this paper, we present the Dynamic Aperture simulations that were employed to identify the operational margins, and therefore define the leveling steps. The results are complemented by observations from nominal operation and projections for the 2018 operation. Additional anti-leveling techniques, investigated in dedicated machine studies are also discussed
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF040
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MOPMF041	Refining the HL-LHC Operational Settings with Inputs From Dynamic Aperture Simulations: A Progress Report	luminosity, octupole, dynamic-aperture, experiment	188
	N. Karastathis, R. De Maria, S.D. Fartoukh, Y. Papaphilippou, D. Pellegrini CERN, Geneva, Switzerland
	Recent Dynamic Aperture (DA) simulations aimed at providing guidance for the latest updates of the operational scenario for the High Luminosity upgrade of the LHC. The impact of the increased chromaticity and octupole current has been assessed considering the latest updates of the optics. Additional means to improve the lifetime, such as tune optimization, have been identified and deployed. We also briefly discuss the impact of delivering high luminosity to the LHCb experiment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF041
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MOPMF050	LHC Operational Experience of the 6.5 TeV Proton Run with ATS Optics	luminosity, optics, emittance, proton	216
	M. Pojer, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, A. Calia, G.E. Crockford, S.D. Fartoukh, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, M. Hostettler, W. Höfle, Y. Le Borgne, D. Nisbet, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli, R. Suykerbuyk, D.J. Walsh, J. Wenninger, M. Zerlauth CERN, Geneva, Switzerland
	In May 2017, the CERN Large Hadron Collider (LHC) restarted operations at 6.5 TeV using the Achromatic Telescopic Squeeze (ATS) scheme with a target beta-star of 40 cm in ATLAS and CMS. The number of bunches was progressively increased to a maximum of 2556 with emittances of 2.5 um. In August, several machine parameters had to be re-tuned to mitigate beam loss induced instabilities and maintain a steady increase of the instantaneous luminosity. The use of a novel beam type and filling pattern produced in the injectors, allowed filling the machine with very low emittance beam (1.5 um) achieving an equivalent luminosity with 1868 bunches. In September, the beta-star was further lowered to 30 cm (using, for the first time, the telescopic technique of the ATS) and the bunch intensity pushed to 1.25·10¹¹ protons. In the last 3 months of 2017, the LHC produced more than 500 pb-1 of integrated luminosity per day, delivering to each of the high luminosity experiments 50.6 fb-1, 10% above the 2017 target. A general overview of the operational aspects of the 2017 proton run will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF050
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MOPMF052	Monitoring and Modeling of the LHC Luminosity Evolution in 2017	luminosity, emittance, experiment, monitoring	224
	N. Karastathis, F. Antoniou, I. Efthymiopoulos, M. Hostettler, G. Iadarola, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, B. Salvachua CERN, Geneva, Switzerland
	In 2017, the Large Hadron Collider (LHC) restarted operation at 6.5 TeV, after an extended end-of-the-year stop, scheduled to deliver 45/fb to the two general-purpose experiments. Continuous monitoring of the key beam parameters and machine configurations that impact the delivered luminosity was introduced, providing fast feedback to operations for further optimisation. The numerical model based on simulations and use of selected machine parameters to estimate the machine luminosity was further developed. The luminosity evolution and comparisons to the model predictions is presented in this paper. The impact of the dynamic variation of the crossing angle, which was incorporated into nominal LHC operation, is also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF052
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MOPMF053	Observations, Analysis and Mitigation of Recurrent LHC Beam Dumps Caused by Fast Losses in Arc Half-Cell 16L2	MMI, electron, vacuum, solenoid	228
	J.M. Jimenez, D. Amorim, S. A. Antipov, G. Arduini, A. Bertarelli, N. Biancacci, B. Bradu, E. Bravin, G. Bregliozzi, K. Brodzinski, R. Bruce, X. Buffat, L.R. Carver, P. Chiggiato, S.D. Claudet, P. Collier, R. Garcia Alia, M. Giovannozzi, L. K. Grob, E.B. Holzer, W. Höfle, G. Iadarola, G. Kotzian, A. Lechner, T.E. Levens, B. Lindstrom, T. Medvedeva, A. Milanese, D. Mirarchi, E. Métral, D. Perini, S. Redaelli, G. Rumolo, B. Salvant, R. Schmidt, M. Valette, D. Valuch, J. Wenninger, D. Wollmann, C. Yin Vallgren, C. Zamantzas, M. Zerlauth CERN, Geneva, Switzerland D. Amorim Université Grenoble Alpes, Grenoble, France A.A. Gorzawski University of Manchester, Manchester, United Kingdom L. Mether EPFL, Lausanne, Switzerland
	Recurrent beam dumps significantly perturbed the operation of the CERN LHC in the summer months of 2017, especially in August. These unexpected beam dumps were triggered by fast beam losses that built up in the cryogenic beam vacuum at the half-cell 16 left of LHC-IP2 and were detected either at that location but mainly in the collimation insertions. This contribution details the experimental observables (beam losses, coherent instabilities, heat load to cryogenic system, vacuum signals), the extent of the understanding of the beam loss and instability mechanisms and the mitigation steps and new settings that allowed recovering the luminosity performance of the LHC for the rest of the Run.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF053
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MOPMF056	The Second LHC Long Shutdown (LS2) for the Superconducting Magnets	dipole, hadron, superconducting-magnet, collider	240
	J.Ph. G. L. Tock, M. Bednarek, L. Bottura, E. Karentzos, S.L.N. Le Naour, F. Meuter, M. Pojer, C.E. Scheuerlein, E. Todesco, D. Tommasini, L. X. Van Den Boogaard, G.P. Willering CERN, Geneva, Switzerland
	The Large Hadron Collider (LHC) has been delivering data to the physics experiments since 2009. It first operated at a centre of mass energy of 7 TeV and 8 TeV up to the first long shutdown (LS1) in 2013-14. The 13 kA splices between the main LHC cryomagnets were consolidated during LS1. Then, it was possible to increase safely the centre of mass energy to 13 TeV. During the training campaigns, metallic debris caused short circuits in the dipole diode containers, leading to an unacceptable risk. Major interventions can only take place during multiyear shutdowns. To ensure safe operation at higher energies, hence requiring further magnets training, the electrical insulation of the 1232 dipole diodes bus-bars will be consolidated during the second LHC long shutdown (LS2) in 2019-20. The design of the reinforced electrical insulation of the dipole cold diodes and the associated project organisation are presented, including the validation tests, especially at cryogenics temperature. During LS2, maintenance interventions on the LHC cryomagnets will also be performed, following the plan based on a statistical analysis of the electrical faults. It is inscribed in the overall strategy to produce collisions at 14 TeV, the LHC design energy, and to push it further towards 15 TeV. We give a first guess on the impact on the LHC failure rate.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF056
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MOPMF062	Upgrade of the Dilution System for HL-LHC	kicker, Windows, damping, simulation	261
	C. Wiesner, W. Bartmann, C. Bracco, M. Calviani, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, S.S. Gilardoni, B. Goddard, T. Kramer, A. Lechner, N. Magnin, A. Perillo-Marcone, T. Polzin, E. Renner, V. Senaj CERN, Geneva, Switzerland
	The LHC Beam Dump System is one of the most critical systems for reliable and safe operation of the LHC. A dedicated dilution system is required to sweep the beam over the front face of the graphite dump core in order to reduce the deposited energy density. The High Luminosity Large Hadron Collider (HL-LHC) project foresees to increase the total beam intensity in the ring by nearly a factor of two, resulting in a correspondingly higher energy deposition in the dump core. In this paper, the beam sweep pattern and energy deposition for the case of normal dilution as well as for the relevant failure cases are presented. The implications as well as possible mitigations and upgrade measures for the dilution system, such as decreasing the pulse-generator voltage, adding two additional kickers, and implementing a retrigger system, are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF062
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MOPMF063	Asynchronous Beam Dump Tests at LHC	proton, extraction, beam-losses, quadrupole	265
	C. Wiesner, W. Bartmann, C. Bracco, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, B. Goddard, C. Heßler, T. Kramer, A. Lechner, N. Magnin, V. Senaj, D. Wollmann CERN, Geneva, Switzerland
	The detailed understanding of the beam-loss pattern in case of an asynchronous beam dump is essential for the safe operation of the future High Luminosity LHC (HL-LHC) with nearly twice the nominal LHC beam intensity, leading to correspondingly higher energy deposition on the protection elements. An asynchronous beam dump is provoked when the rise time of the extraction kickers is not synchronized to the 3 us long particle-free abort gap. Thus, particles that are not absorbed by dedicated protection elements can be lost on the machine aperture. Since asynchronous beam dumps are among the most critical failure cases of the LHC, experimental tests at low intensity are performed routinely. This paper reviews recent asynchronous beam dump tests performed in the LHC. It describes the test conditions, discusses the beam-loss behaviour and presents simulation and measurement results. In particular, it examines a test event from May 2016, which led to the quench of four superconducting magnets in the extraction region and which was studied by a dedicated beam experiment in December 2017.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF063
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MOPML009	New High Luminosity LHC Baseline and Performance at Ultimate Energy	luminosity, optics, emittance, cavity	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
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MOPML024	Implementation of a Non-Invasive Online Beam Monitor at a 60 MeV Proton Therapy Beamline	detector, proton, cyclotron, monitoring	449
	R. Schnuerer, C.P. Welsch, S.L. Yap, H.D. Zhang Cockcroft Institute, Warrington, Cheshire, United Kingdom O. Girard, G.J. Haefeli EPFL, Lausanne, Switzerland C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	To fully exploit the advantageous dose distribution profiles of ion radiotherapy, an exact knowledge of the beam properties through online beam monitoring is essential, ensuring thus an effective dose delivery to the patient. One potential candidate for an online beam monitor is the LHCb Vertex Locator (VELO). This detector, originally developed for the LHCb experiment, has been adapted to the specific conditions of the clinical environment in a proton therapy centre. The semicircular design and position of its sensitive silicon detector offers a non-invasive way to measure the beam intensity without interfering with the beam core. In this contribution, modifications for VELO are described. The detector is synchronized with the readout of a locally-constructed Faraday Cup and the 25.7 MHz RF frequency of the cyclotron at the Clatterbridge Cancer Centre (CCC). Geant4 Monte Carlo simulations investigate the integration of the detector in the treatment line and behaviour of the beam during delivery. The capability of VELO as a beam monitor will be assessed by measuring the beam current and by monitoring the beam profile along the beamline this summer.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML024
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MOPML031	Highlights of Accelerator Activities in France on Behalf of the Accelerator Division of the French Physics Society	linac, laser, proton, electron	470
	J.-L. Revol ESRF, Grenoble, France S. Chel CEA/IRFU, Gif-sur-Yvette, France B. Cros CNRS LPGP Univ Paris Sud, Orsay, France N. Delerue LAL, Orsay, France E. Giguet ALSYOM, Versailles, France V. Le Flanchec CEA/DAM, Bruyères-le-Châtel, France L.S. Nadolski SOLEIL, Gif-sur-Yvette, France L. Perrot IPN, Orsay, France A. Savalle GANIL, Caen, France T. Thuillier LPSC, Grenoble Cedex, France
	The French Physical Society is a non-profit organization working to advance and diffuse the knowledge of physics. Its Accelerators division contributes to the promotion of accelerator activities in France. This paper presents the missions and actions of the division, high-lighting those concerning young scientists. A brief presentation of the laboratories, institutes, and facilities that are the main actors in the field is given. Significant ongoing and planned projects in France are described, including medical applications. Main French contributions in inter-national projects are then listed. Finally, cultural and technical relationships between industry and laboratories are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML031
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MOPML033	Data Supply of Accelerator Devices - Data Management of Device Process Data at a Medical Accelerator	controls, database, MMI, linac	477
	M. Galonska, R. Cee, Th. Haberer, K. Höppner, J.M. Mosthaf, A. Peters, S. Scheloske, C. Schömers HIT, Heidelberg, Germany
	HIT is the first dedicated proton and carbon cancer therapy facility in Europe. It uses the full 3D intensity controlled raster scanning dose delivery method of pencil beams with ion beams of 48 - 430 MeV/u provided by a linac-synchrotron-system. Ion beams in this wide range of energies, different beam sizes, and intensities have to be provided by the control system to all treatment rooms at any time with high accuracy, stability, and reproducibility. This paper briefly reflects some aspects of the data supply, i. e. the settings of accelerator devices at a medical accelerator. This includes the generation of control data, storage, and data recovery routines, which have been developed at HIT in the recent years. That is in particular the management of verified therapy data and settings, which are stored in a non-volatile memory of the device controllers, and – as a backup – in a database and which are protected against unintended changes for safety reasons.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML033
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MOPML048	Design Study of PM Dipole for ILC Damping Ring	dipole, permanent-magnet, damping, radiation	505
	Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan N. Terunuma KEK, Ibaraki, Japan
	Dipole magnet using permanent magnet technology is under investigation for ILC cost reduction. It can reduce cost of electricity of coil excitation and cooling water pump, thick electric cabling and water piping, power supply, and their maintenance cost. The structure and the field adjustment scheme will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML048
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MOPML053	Mu*STAR Accelerator-Driven Subcritical Reactors Burning Spent Nuclear Fuel at Light-Water-Reactor Sites	target, site, neutron, SRF	524
	R.P. Johnson, R.J. Abrams, M.A. Cummings, T.J. Roberts Muons, Inc, Illinois, USA
	This project will use modeling and simulation tools to optimize many aspects of the MuSTAR design and begin to explore accident scenarios. At present we have a conceptual design of the accelerator, the reactor, the spallation target, and the fractional distillation to separate volatile fission products. Our GAIN project with ORNL is preparing a design of the Fuel Processing Plant that will convert spent nuclear fuel into the molten-salt fuel for MuSTAR. This includes all of the nuclear components, but not such things as the turbine and generator, physical plant, control and monitoring systems, etc. We currently have basic simulations of the reactor neutronics, and a start at calculating the fuel evolution. These have used MCNP and ORIGEN, and initial results have been reported1. This project will support the use of additional neutronics and multi-physics codes, enabling a much more thorough analysis of the system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML053
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TUXGBD2	Colliding Heavy Ions in the LHC	luminosity, heavy-ion, experiment, proton	584
	J.M. Jowett CERN, Geneva, Switzerland
	The Large Hadron Collider at CERN not only collides protons but also heavier nuclei. So far Pb+Pb, Xe-Xe and p+Pb collisions, at multiple energies, have been provided for what was initially conceived as a distinct physics program on the collective behavior of QCD matter at extreme energy density and temperature. However unexpected phenomena observed in p+Pb and p+p collisions at equivalent energies have blurred the distinction. Intense, low-emittance, ion beams are provided by a dedicated source and injector chain setup. When Pb beams collide, new luminosity limits arise from photon-photon and photonuclear interactions but effective mitigations have allowed luminosities over 3 times design. Asymmetric p+Pb collisions introduce new features and beam-dynamical phenomena into operation of the LHC but have also achieved luminosity far beyond expectations. With experimental requirements for multiple changes in energy and data-taking configurations during very short heavy-ion runs, high operational efficiency and reliability are vital. This invited talk discusses performance, future prospects, and technical challenges for the LHC heavy ion program, including injector performance.
	Slides TUXGBD2 [5.317 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBD2
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TUYGBD2	A Review of DAΦNE Performances During the KLOE-2 Run	luminosity, detector, vacuum, collider	624
	C. Milardi, D. Alesini, S. Bini, O.R. Blanco-García, M. Boscolo, B. Buonomo, S. Cantarella, S. Caschera, A. D'Uffizi, A. De Santis, G.O. Delle Monache, D.G.C. Di Giulio, G. Di Pirro, A. Drago, L.G. Foggetta, A. Gallo, R. Gargana, A. Ghigo, S. Guiducci, C. Ligi, M. Maestri, A. Michelotti, L. Pellegrino, R. Ricci, U. Rotundo, A. Stecchi, A. Stella, M. Zobov INFN/LNF, Frascati (Roma), Italy
	DAΦNE, the Frascati electron-positron accelerator complex, has almost completed the last and more chanlleging period of operation for the KLOE-2 detector. In this context the performances of the collider, based on the Crab-Waist collision scheme, are reviewed and the limiting factors discussed.
	Slides TUYGBD2 [9.928 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBD2
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TUPAF001	Requirements for the Cryogenic Refrigerator and the He Distribution System for the MYRRHA 100 Mev Accelerator	linac, cryogenics, cavity, cryomodule	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.
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TUPAF012	Commissioning of the Lipac Medium Energy Beam Transport Line	cavity, vacuum, rfq, controls	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).
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TUPAF023	The Beamlines of the CERN East Area Renovation Project	target, secondary-beams, radiation, experiment	717
	J. Bernhard, M. Bonnet, Q. Bouirek, D. Brethoux, B.D. Carlsen, A. Ebn Rahmoun, J. Etheridge, S. Evrard, L. Gatignon, E. Harrouch, M. Lazzaroni, M. Van Dijk, A. Watrigant CERN, Geneva, Switzerland
	The East Area at the Proton Synchrotron is one of CERN's longest running facilities for experiments, beam tests, and irradiations with a successful history of over 55 years. The facility serves more than 20 user teams for about 200 days of running each year and offers mixed secondary hadron, electron and muon beams of 0.5 GeV/c to 10 GeV/c. In addition, the primary proton beam or ion beam is transported to the irradiation facilities CHARM and IRRAD. Due to the steadily high user demand, the CERN management approved an upgrade and renovation of the facility to meet future beam test and physics requirements. New beam optics will assure a better transmission and purity of the secondary beams, now also with the possibility of highly pure electron, hadron or muon beams. The upgrade includes a pulsed powering scheme with energy recovering power supplies and new magnets, reducing both power and cooling requirements. Together with the building consolidation, this results in a considerably lower energy consumption. The renovation phase is scheduled during the technical stops between 2018 and 2020. We will give an overview of the project scope including upgrades and future beams.
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TUPAF025	Multi-turn Study in FLUKA for the Design of CERN-PS Internal Beam Dumps	dumping, simulation, experiment, proton	724
	J.A. Briz Monago, M. Calviani, F. Cerutti, J.J. Esala, S.S. Gilardoni, F.-X. Nuiry, G. Romagnoli, G. Sterbini, V. Vlachoudis CERN, Geneva, Switzerland
	The CERN Proton-Synchrotron (PS) accelerator is currently equipped with two internal beam dumps in operation since the 1970's. An upgrade is required to be able to withstand the beams that will be produced after the end of the LIU (LHC Injector Upgrade) project. For the design of the new dumps, the interaction and transport of beam and all secondary particles generated has been simulated using FLUKA. The working principle of the internal beam dump in the PS ring is very peculiar with respect to the other dumps in the CERN accelerator complex. A moving dump intercepts the circulating beam during few milliseconds like a fast scraper. The moving dump shaving the beam, the multi-turn transport of beam particles in the PS accelerator and a time-dependent energy deposition in the dump were modeled. The methodology and the results obtained in our studies for the dump core and downstream equipment will be reported in this contribution.
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TUPAF029	Observation of Fast Losses in the LHC Operation in 2017	detector, betatron, beam-losses, monitoring	740
	A.A. Gorzawski, N. Fuster-Martínez, S. Redaelli, C. Xu, C. Zamantzas CERN, Geneva, Switzerland R.B. Appleby UMAN, Manchester, United Kingdom H. Garcia Morales Royal Holloway, University of London, Surrey, United Kingdom
	Four diamond detectors that provide beam loss measurements with time resolution in the nanosecond range were added in the vicinity of the primary collimators of the Large Hadron Collider (LHC). This is a powerful diagnostic tool that provides the unique chance to measure bunch-by-bunch losses. The operation of the LHC in 2017 presented several unusual events of fast, high intensity beam losses, many of them captured by the diamond detectors in the betatron cleaning region. In this paper we review some of the relevant loss cases that were analyzed in the wider scope of determining the source of the instability generating these losses. We show few of the possible applications of this detectors in daily operations.
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TUPAF031	Beam Simulation Studies for the Upgrade of the SPS Beam Dumping System	kicker, simulation, dumping, injection	747
	C. Heßler, W. Bartmann, E. Carlier, L. Ducimetière, B. Goddard, F.M. Velotti CERN, Geneva, Switzerland
	The SPS at CERN currently uses a beam dumping system that is installed in the long straight section 1 (LSS1) of the SPS. This system consists of two beam stopper blocks for low and high energy beams, as well as two vertical and three horizontal kicker magnets, which deflect and dilute the beam on the dumps. Within the frame of the LHC injector upgrade project (LIU) the beam dumping system will be relocated to long straight section 5 (LSS5) and upgraded with an additional vertical kicker, new main switches and a single new beam dump, which covers the full energy range. The impact of a possible increase of the vertical kicker rise time on the beam has been studied in simulations with MAD-X for the different optics in the SPS. Furthermore, the impact on the beam in failure scenarios such as the non-firing of one kicker has been investigated. The results of these studies will be presented and discussed in this paper. Operational mitigation methods to deal with an increased rise time will also be discussed.
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TUPAF038	Prototyping Activities for a New Design of CERN's Antiproton Production Target	target, proton, experiment, antiproton	772
	C. Torregrosa, M.E.J. Butcher, M. Calviani, J.P.C. Espadanal, R. Ferriere, L. Gentini, E. Grenier-Boley, L. Mircea Grec, A. Perillo-Marcone, R. Seidenbinder, N.S. Solieri, M.A. Timmins, E. Urrutia, V. Vlachoudis CERN, Geneva, Switzerland
	Antiprotons are produced at CERN by impacting intense proton beams of 26 GeV/c onto a high-Z water-cooled target. The current design consists in an Ir core target in a graphite matrix and inserted in a Ti-6Al-4V assembly. A new target design has been foreseen for operation after 2021 aiming at improving the operation robustness and antiproton production yield, triggering several R&D activities during the last years. First, both numerical (use of hydrocodes) and experimental approaches were carried out to study the core material response under extreme dynamic loading when impacted by the primary proton beam. The lessons learnt from these studies have been then applied to further prototyping and testing under proton beam impact at the CERN-HiRadMat facility. A first scaled prototype consisting in Ta rods embedded in an expanded graphite matrix was irradiated in 2017, while in 2018, the PROTAD experiment will test different real-scale AD-Target prototypes, in which the old water-cooled assembly is replaced by a more compact air-cooled one, and different core geometry and material configurations are investigated. This contribution details these prototyping and testing activities.
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TUPAF040	Beam Loss Measurements for Recurring Fast Loss Events During 2017 LHC Operation Possibly Caused by Macroparticles	proton, simulation, dipole, insertion	780
	A. Lechner, B. Auchmann, E. Bravin, A.A. Gorzawski, L. K. Grob, E.B. Holzer, B. Lindstrom, T. Medvedeva, D. Mirarchi, R. Schmidt, M. Valette, D. Wollmann CERN, Geneva, Switzerland
	The availability of the LHC machine was adversely affected in 2017 by tens of beam aborts provoked by frequent loss events in one standard arc cell (16L2). In most of the cases, the dumps were triggered by concurrently developing fast beam instabilities leading to particle losses in the betatron cleaning insertion. Many of the events started with a distinct sub-millisecond loss peak comparable to regular dust particle events, which have been observed along all the LHC since the start-up. In contrast to regular dust events, persistent losses developed in cell 16L2 after the initial peaks which can possibly be explained by a phase transition of macroparticles to the gas phase. In this paper, we summarize the observed loss characteristics such as spatial loss pattern and time profiles measured by Beam Loss Monitors (ionization chambers). Based on the measurements, we estimate the energy deposition in macroparticles and reconstruct proton loss rates as well as the gas densities after the phase transition. Differences between regular dust events and events in 16L2 are highlighted and the ability to induce magnet quenches is discussed.
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TUPAF049	Analysis of Loss Signatures of Unidentified Falling Objects in the LHC	proton, beam-losses, vacuum, electron	814
	L. K. Grob, M. Dziadosz, E.B. Holzer, A. Lechner, B. Lindstrom, R. Schmidt, D. Wollmann, C. Zamantzas CERN, Geneva, Switzerland
	Particulates in the LHC beam pipes can interact with the proton beams and cause significant beam losses. The "UFOs" (unidentified falling objects) hypothesis describes a particle falling into the beam, creating particle showers, being ionized and repelled. Though the signals of the beam loss monitors support this, many aspects remain unknown. Neither the source of the dust nor the release mechanism from the beam pipe are understood. The same holds for the forces involved in the interaction and the observed UFO rate reduction over the years. These open questions are approached from different angles. Firstly, a new data analysis tool was established featuring advanced raw data selection and statistical analysis. Results of this analysis will be presented. Secondly, dust samples were extracted from LHC components and analyzed to gain insight into the size distribution and material composition of the contamination. The performed observations and analysis lead to a better modelling of the UFO events and helped to understand the physics involved. The validated UFO models will be crucial in view of the high luminosity upgrade of the LHC (HL-LHC) and the Future Circular Collider (FCC).
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TUPAF052	Effects of Electrostatic Septum Alignment on Particle Loss During Slow Extraction at CERN SPS	alignment, extraction, simulation, septum	826
	J. Prieto, Y. Dutheil, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel, F.M. Velotti CERN, Geneva, Switzerland M.A. Kagan SLAC, Menlo Park, California, USA
	Slow extraction is an intrinsically lossy process that splits the beam with an electrostatic septum (ES), employing a thin-wire array to delimit the high electric field region that deflects the beam into the extraction channel. At CERN's Super Proton Synchrotron (SPS) the ES is over 16 m long and composed of 5 separate units containing separate wire-arrays that can be moved independently. The tanks are all mounted on a single support structure that can move the ensemble coherently. As a result, the large number of positional degrees of freedom complicates the alignment procedure in operation. Obtaining and maintaining accurate alignment of the ES with the beam is therefore crucial for minimising beam loss. In this paper, we investigate the alignment procedure for different operational scenarios using particle tracking simulations to understand the beam loss along the extraction straight as a function of the relative positions of each of the 5 separate ES units. An important aspect of the study was to understand the required alignment tolerance to achieve optimum extraction efficiency for a given configuration of wire-array thicknesses.
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TUPAF054	Slow Extraction Efficiency Measurements at the CERN SPS	extraction, proton, septum, simulation	834
	M.A. Fraser, K. Cornelis, L.S. Esposito, B. Goddard, V. Kain, F. Roncarolo, L.S. Stoel, F.M. Velotti CERN, Geneva, Switzerland
	The high efficiency of most slow extraction systems makes quantifying the exact amount of beam lost in the process extremely challenging. This is compounded by the lack of time structure in the extracted beam, as is typically required by the high-energy physics experiments, and the difficulty in accurately calibrating D.C. intensity monitors in the extraction line at count rates of ~ 10¹³ Hz. As a result, it is common for the extraction inefficiency to be measured by calibrating the beam loss signal induced by the slow extraction process itself. In this paper, measurements of the extraction efficiency performed at the CERN Super Proton Synchrotron for the third-integer resonant slow extraction of 400 GeV protons over recent years will be presented and compared to expectation from simulation. The technique employed will be discussed along with its limitations and an outlook towards a future online extraction efficiency monitoring system will be given.
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TUPAF057	The SPS Tests of the HL-LHC Crab Cavities	cavity, cryomodule, vacuum, HOM	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.
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TUPAF062	Parametric Study of the Beam Footprint Characteristics on the ESS Target	target, linac, HOM, ion-source	866
	R. Miyamoto ESS, Lund, Sweden H.D. Thomsen ISA, Aarhus, Denmark
	The beam delivery system of the ESS linac utilizes fast oscillating triangular wave dipole magnets of two transverse planes (raster magnets) to spray each long beam pulse (2.86 ms) over a rectangular cross-check pattern on the target. The characteristics of this beam footprint on the target are determined by the amplitudes of the raster magnets, RMS sizes of the beam and, in some case, the tail of the beam profile and have to satisfy the requirements from the target for the peak density as well as the fraction outside of a given rectangular boundary. This paper presents approximate closed-form expressions for the characteristics of the beam footprint and, based on the presented expressions, explores the parameter space of the raster magnets and beam parameters for achieving the optimal characteristics of the beam footprint.
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TUPAF080	Final Design of the FoS Alvarez-Cavity-Section for the Upgraded UNILAC	cavity, DTL, quadrupole, 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.
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TUPAF085	Status of Link Existing Facility Project for FAIR	linac, shielding, radiation, synchrotron	934
	J. Stadlmann, C. Omet, A. Schuhmann, P.J. Spiller GSI, Darmstadt, Germany
	The project "Link existing Facility", or GaF (GSI Anbindung an FAIR), is an important subproject of the overall FAIR facility. In order to serve as injector for SIS100, the main accelerator of FAIR, the existing GSI synchrotron SIS18 is undergoing an upgrade program leading to about 100 times higher beam intensities. Especially the foreseen operation with 4 GeV Protons with up to 5·10¹² protons per second increases the radiation protection requirements to such an extent that the existing radiation protection measures are no longer sufficient. The project consists of 78 individual measures. The four most substantial activities are the construction of a table-like structure to carry additional shielding. The creation of an opening and a first part of transfer tunnel for the beamlines towards the future FAIR campus. The preparation for the building, beam dump and connection of the FAIR proton injector. The incorporation of state-of-the-art radiation- and fire-protection measures into the present facilities including the a new technical building to house technical infrastructure. We report on the project status which is foreseen to finish mid-2018.
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TUPAF086	Adaption of the HSI -RFQ Rf-Properties to an Improved Beam Dynamics Layout	simulation, rfq, linac, resonance	938
	M. Vossberg, L. Groening, S. Mickat, H. Vormann, C. Xiao GSI, Darmstadt, Germany V. Bencini, J.M. Garland, J.-B. Lallement, A.M. Lombardi CERN, Geneva, Switzerland
	The GSI accelerator facility comprising the linear accelerator UNILAC and the synchrotron SIS18 will be used in future mainly as the injector for the Facility for Anti-Proton and Ion Research (FAIR) being under construction. FAIR requires high beam brilliance and the UNILAC's RFQ electrodes must be upgraded with respect to their beam dynamics design. The new layout is currently being conducted at CERN with the aim of adjusting the electrode voltage according to the design voltage of 123 kV. CST simulations performed at GSI assure that the resonance frequency with the new electrode geometry is recuperated through corrections of the carrier rings. Simulations on the frequency dependence of the rings shapes and their impact on the voltage distribution along the RFQ are presented.
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TUPAK001	Progress of the Modulated 325 MHz Ladder RFQ	rfq, linac, proton, quadrupole	952
	M. Schuett, U. Ratzinger, M. Syha IAP, Frankfurt am Main, Germany
	Funding: BMBF 05P15RFRBA Based on the positive results of the unmodulated 325 MHz Ladder-RFQ prototype from 2013 to 2016, we developed and designed a modulated 3.3 m Ladder-RFQ. The unmodulated Ladder-RFQ features a very constant voltage along the axis. It accepted 3 times the operating power of which is needed in operation. That level corresponds to a Kilpatrick factor of 3.1 with a pulse length of 200 μs. The 325 MHz RFQ is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the proton linac within the FAIR project. This particular high frequency creates difficulties for a 4-ROD type RFQ, which triggered the development of a Ladder RFQ with its high symmetry. The results of the unmodulated prototype have shown, that the Ladder-RFQ is a suitable candidate for that frequency. The duty cycle is suitable up to 5%. The basic design and tendering of the RFQ has been successfully completed in 2016. Manufacturing will be completed in May 2018. We will show the latest results of manufacturing, beam dynamics simulations for the matching between LEBT and RFQ. Journal of Physics: Conf. Series 874 (2017) 012048 **Proceedings of LINAC2016, East Lansing, TUPLR053
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TUPAK005	Upgrade Plan of J-PARC MR - Toward 1.3 MW Beam Power	experiment, injection, proton, cavity	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.
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TUPAK010	The Development of a New Low Field Septum Magnet System for Fast Extraction in Main Ring of J-PARC	septum, power-supply, controls, feedback	981
	T. Shibata, K. Ishii, H. Matsumoto, T. Sugimoto KEK, Ibaraki, Japan K. Fan HUST, Wuhan, People's Republic of China
	The J-PARC Main Ring (MR) is being upgraded to improve its beam power to the design goal of 750 kW. One important way is to reduce the repetition period from 2.48 s to 1.3 s so that the beam power can be nearly doubled. We need to improve the septum magnets for fast extraction. We are improving the magnets and their power supplies. The present magnets which are conventional type have problem in durability of septum coil by its vibration, and large leakage field at the flange of the beam duct. The new magnets are eddy current type. The eddy current type does not have septum coil, but has a thin plate. We expect that there is no problem in durability, we can construct the thin septum plate, the leakage field can be reduced. The output of the present power supply are pattern current which of flat top is 10 ms width, the new one is short pulse which of one is 10 us. The short pulse consists of 1st and 3rd higher harmonic. We can expect that the flatness and reproducibility of flat top current can be improved. The calorific power can be also reduced. This paper will report the performance of the power supply and its magnetic field with the eddy septum magnet systems.
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TUPAK011	Present Status and Future Upgrades of the J-PARC Ring RF Systems	proton, cavity, power-supply, 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.
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TUPAK012	Conceptual Design of a Single-Ended MA Cavity for J-PARC RCS Upgrade	cavity, acceleration, 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.
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TUPAL011	Low Power Test and Tuning of the LEAF RFQ	rfq, quadrupole, cavity, dipole	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.
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TUPAL017	Performance and Status of the J-PARC Accelerators	target, linac, ion-source, status	1038
	K. Hasegawa, N. Hayashi, M. Kinsho, H. Oguri, K. Yamamoto, Y. Yamazaki JAEA/J-PARC, Tokai-mura, Japan T. Koseki, F. Naito, M. Yoshii KEK, Tokai, Ibaraki, Japan N. Yamamoto J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	The J-PARC is a high intensity proton facility and the accelerator consists of a 400 MeV linac, a 3 GeV Rapid Cycling Synchrotron (RCS) and a 30 GeV Main Ring Synchrotron (MR). Regarding 3 GeV beam from the RCS, we delivered it at 150 kW to the materials and life science experimental facility (MLF), for the neutron and muon users. The beam powers for the neutrino experiment at 30 GeV was 420 kW in May 2016, but increased to 470 kW in February 2017 thanks to the change and optimization of operation parameters. For the hadron experimental facility which uses a slow beam extraction mode at 30 GeV, we delivered beam at a power of 37 kW, after the recovery from a trouble at an electro static septum. We have experienced many failures and troubles to impede full potential and high availability. In this report, operational performance and status of the J-PARC accelerators are presented.
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TUPAL018	Pulse-by-Pulse Switching of Operational Parameters in J-PARC 3-GeV RCS	emittance, injection, extraction, betatron	1041
	H. Hotchi, H. Harada, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, Y. Watanabe, M. Yoshimoto JAEA/J-PARC, Tokai-mura, Japan
	J-PARC 3-GeV RCS (rapid cycling synchrotron) provides a high-power beam both to MLF (materials and life science experimental facility) and MR (main ring synchrotron) by switching the beam destination pulse by pulse. The beam properties required from MLF and MR are different; MLF needs a wide-emittance beam with less charge density, while MR requires a low-emittance beam with less beam halo. To meet the antithetic requirements while keeping beam loss at permissible levels, RCS has recently initiated pulse-by-pulse switching of operational parameters (betatron tune, chromaticity, painting emittance, etc.). This paper presents the recent efforts toward the performance upgrade of RCS while discussing the related beam dynamics issues.
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TUPAL020	Recent Status of J-PARC Rapid Cycling Synchrotron	injection, target, emittance, proton	1045
	K. Yamamoto, P.K. Saha JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) provides more than 300 kW beam to the Material and Life Science Facility (MLF) and the Main Ring (MR). In such high intensity hadron accelerator, the lost protons that are a fraction of the beam less than 0.1 % cause many problems. Those particles bring about a serious radioactivation and a malfunction of the accelerator components. Therefore, we carried out the beam study to achieve high power beam operation. Moreover, we also maintain the accelerator components to keep a steady operation. We report present status of the J-PARC RCS.
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TUPAL029	Harmonictron	acceleration, cavity, proton, 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.
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TUPAL034	Effect of 805-MHz Linac RF Stability on Beam Losses in LANSCE High-Energy Beamlines	beam-losses, linac, neutron, proton	1078
	Y.K. Batygin 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. Operation of an accelerator facility critically depends on stability of the field amplitudes and phases of the accelerating cavities. The LANSCE linear accelerator consists of a 201.25-MHz, drift-tube linac and an 805-MHz, side-coupled-cavity linac (SCL). Beam losses in the high-energy beamlines of the 800-MeV facility were measured versus variation of the amplitudes and phases of the 805-MHz, SCL, RF cavities. A recent study* confirms that to achieve low losses, the stability of the amplitudes and phases should be kept within 0.1% and 0.1o, respectively. This agrees with a previous study of beam losses in the 201.25-MHz linac. Details of the measurements and results are presented. *L.J.Rybarcyk, R.C.McCrady, Proceeding of LINAC2016, East Lansing, MI, USA, MOPLR072, p.301.
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TUPAL045	Towards Operational Scalability for H⁻ Laser Assisted Charge Exchange	laser, experiment, cavity, 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.
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TUPAL046	Construction, Test, and Operation of a new RFQ at the Spallation Neutron Source (SNS)	rfq, linac, ion-source, vacuum	1113
	Y.W. Kang, A.V. Aleksandrov, W.E. Barnett, M.S. Champion, M.T. Crofford, B. Han, S.W. Lee, J. Moss, R.T. Roseberry, J.P. Schubert, A.P. Shishlo, M.P. Stockli, C.M. Stone, R.F. Welton, D.C. Williams, A.P. Zhukov ORNL, Oak Ridge, Tennessee, USA C.C. Peters, J. Price ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: * This work was supported by SNS through UT-Battelle, LLC, under contract DEAC0500OR22725 for the U.S. DOE. A new RFQ was successfully installed recently in the SNS linac to replace the old RFQ that was used for more than a decade with certain operational limitations. The new RFQ was completely tested with H⁻ ion source in the Beam Test Facility (BTF) at SNS. For robust operation of SNS at 1.4 MW, the full design beam power and to satisfy the beam current requirement of the forthcoming SNS proton power upgrade (PPU) project, an RFQ with enhanced performance and reliability was needed. The new RFQ was built to have the beam parameters identical to those of the first RFQ but with improved RF and mechanical stability and reliability for continuous operation of neutron production. The tests confirmed that the new RFQ can run with high beam transmission efficiency at around 90 % and notably improved operational stability. In this paper, construction, test, installation, and operation of the new RFQ in SNS are discussed with the performance improvements.
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TUPAL052	Multi-Physics Analysis of a CW IH-DTL for CIFNEF	DTL, cavity, neutron, linac	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.
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TUPAL055	Progress with Carbon Stripping Foils at ISIS	synchrotron, vacuum, injection, proton	1136
	B. Jones, H.V. Cavanagh STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The ISIS Facility at the Rutherford Appleton Laboratory produces intense neutron and muon beams for condensed matter research. The facility's 50Hz rapid cycling synchrotron accelerates protons from 70 to 800MeV to deliver a mean beam power of 0.2MW to two target stations. Since 2016, ISIS has routinely used commercially produced carbon based foils for beam stripping during charge-exchange injection. Recent experience and developments to increase useful foil lifetime are presented including in-house high temperature annealing of foils prior to use. The installation and performance of a new foil imaging system are described and, finally, the procedure to change the stripping foil is described. Issues with the current arrangements and options for redesign are discussed.
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TUPAL057	Preliminary Experiments in Caesium Delivery and Gettering on the ISIS Vespa Source	experiment, ion-source, plasma, site	1144
	T. M. Sarmento, R.E. Abel, D.C. Faircloth, S.R. Lawrie, J.H. Macgregor, M. Whitehead, T. Wood STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	Caesium capture by graphite at various temperatures 20- 300°C in the VESPA ion source test stand was explored in a preliminary experiment. An accompanying experiment was set up to evaluate the control of caesium boiler delivery in the various ISIS penning sources. Results indicate Cs flux fluctuates at constant settings, which must be accounted for to interpret graphite gettering results. Future studies to identify the cause of fluctuations are considered, and a more rigorous experiment to study the use of graphite is introduced.
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TUZGBE2	Final-focus Superconducting Magnets for SuperKEKB	solenoid, quadrupole, MMI, detector	1215
	N. Ohuchi, K.A. Aoki, Y. Arimoto, M.K. Kawai, T. Kawamoto, H. Koiso, Y. Kondo, M. Masuzawa, A. Morita, S. Nakamura, Y. Ohnishi, Y. Ohsawa, T. Oki, H. Sugimoto, K. Tsuchiya, R. Ueki, X. Wang, H. Yamaoka, Z.G. Zong KEK, Ibaraki, Japan M. Anerella, J. Escallier, A.K. Jain, A. Marone, B. Parker, P. Wanderer BNL, Upton, Long Island, New York, USA J. DiMarco, T.G. Gardner, J.M. Nogiec, M.A. Tartaglia, G. Velev Fermilab, Batavia, Illinois, USA T.-H. Kim Mitsubishi Electric Corp, Advanced Technology R & D Center, Hyogo, Japan
	The SuperKEKB collider aims at 40 times higher luminosity than that achieved at KEKB, based on the nano-beam scheme. The vertical beta function at the interaction point will be squeezed to 300μmeter. Final-focus superconducting magnet system which consists of eight main quadrupole magnets, 43 corrector windings, and compensation solenoids is a key component to achieve high luminosity. This invited talk presents the construction and commissioning of the final-focus magnet system.
	Slides TUZGBE2 [4.235 MB]
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TUZGBE3	Towards Implementation of Laser Engineered Surface Structures for Electron Cloud Mitigation	electron, laser, vacuum, multipactoring	1220
	M. Sitko, V. Baglin, S. Calatroni, P. Chiggiato, B. Di Girolamo, E. Garcia-Tabares Valdivieso, M. Taborelli CERN, Geneva, Switzerland A. Abdolvand, D. Bajek, S. Wackerow University of Dundee, Nethergate, Dundee, Scotland, United Kingdom M. Colling, T.J. Jones, P.A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The LHC operation has proven that the electron cloud could be a significant limiting factor in machine performance, in particular for future High Luminosity LHC (HL-LHC) beams. Electron clouds, generated by electron multipacting in the beam pipes, leads to beam instabilities and beam-induced heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) is a novel surface treatment which changes the morphology of the internal surfaces of vacuum chambers. The surface modification results in a reduced secondary electron yield (SEY) and, consequently, in the eradication of the electron multipacting. Low SEY values of the treated surfaces and flexibility in choosing the laser parameters make LESS a promising treatment for future accelerators. LESS can be applied both in new and existing accelerators owing to the possibility of automated in-situ treatment. This approach has been developed and optimised for the LHC beam screens in which the electron cloud has to be mitigated before the HL-LHC upgrade. We will present the latest steps towards the implementation of LESS.
	Slides TUZGBE3 [1.825 MB]
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TUZGBE5	A Combined Temperature and Magnetic Field Mapping System for SRF Cavities	cavity, 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]
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TUPMF007	Cryogenic Testing and Initial Performance of a Helical Superconducting Undulator at the APS	vacuum, undulator, cryogenics, radiation	1260
	J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, M. Kasa, I. Kesgin, Y. Shiroyanagi ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science under Contract No. DE-AC02-06CH11357. A helical superconducting undulator (HSCU) has been installed and is presently operational at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). We describe the final assembly and cryogenic test program which led to successful operation, representing the culmination of a two-year development effort. Details of the cryostat and cryogenic system design are presented along with as-installed performance data and a comparison with design expectations.
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TUPMF018	Simulation Studies of the Helical Superconducting Undulator Installed at APS	multipole, simulation, undulator, storage-ring	1290
	A. Xiao, V. Sajaev, Y.P. Sun ANL, Argonne, Illinois, USA
	A multi-year project at APS has resulted in construction of a helical superconducting undulator (HSCU) for installation in the ring. Before installation, simulation studies were done to ensure that APS performance will not be compromised. This paper describes the method used for calculating the HSCU's perturbation effects and the simulation results for both calculated and measured field map. Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
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TUPMF025	LEReC Photocathode DC Gun Beam Test Results	gun, cathode, laser, electron	1306
	D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, X. Gu, L.R. Hammons, P. Inacker, J.P. Jamilkowski, J. Kewisch, C.J. Liaw, C. Liu, K. Mernick, T.A. Miller, M.G. Minty, V. Ptitsyn, T. Rao, J. Sandberg, S. Seletskiy, P. Thieberger, J.E. Tuozzolo, E. Wang, Z. Zhao BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Low Energy RHIC Electron cooler (LEReC) project is presently under commissioning at Brookhaven National Laboratory (BNL). LEReC requires high average current up to 85mA and high-quality electron beam. A 400 kV DC gun equipped with a photocathode and laser system has been chosen to provide a source of high-quality electron beams. We started testing the DC gun during the RHIC run 2017. First electron beam from LEReC DC gun was delivered in April 2017 . During the DC gun test critical elements of LEReC such as laser beam system, cathode exchange system, cathode QE lifetime, DC gun stability, beam instrumentation, the high-power beam dump system, machine protection system and controls have been tested. Average current of 10 mA for few hours of operation was reached in August 2017. In this paper we present experimental results and experience learned during the LEReC DC gun beam testing. D. Kayran et al., "First Results of Commissioning DC Photo-gun for RHIC Low Energy Electron Cooler (LEReC)", in Proc of ERL2017.
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TUPMF030	Operation and Performance of NSLS-II	emittance, feedback, MMI, photon	1312
	G.M. Wang BNL, Upton, Long Island, New York, USA
	NSLS-II facility hosts 23 operating beamlines with 2 more under commissioning. The radiation sources varies, including damping wiggler, IVU, EPU, 3PW, and bending magnets. Over the past year, the storage ring performance continuously improved, including frequency feedback and photon local feedback. Machine reliability reached 96.9% for 4500 hrs operation with beam current upto 350 mA. Beam orbit short and long term stability has been significantly improved. Operation beam emittance were optimized with beamlines.
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TUPMF035	First Demonstration of the Transparent Fast-to-slow Corrector Current Shift in the NSLS-II Storage Ring	feedback, experiment, lattice, photon	1323
	X. Yang, V.V. Smaluk, Y. Tian, L. Yu BNL, Upton, Long Island, New York, USA
	To realize the full benefits of the high brightness and ultra-small beam sizes of NSLS-II, it is essential that the photon beams are exceedingly stable (a level of 10% beam size). In the circumstances of implementing local bumps, changing ID gaps, and long-term drifting, the fast orbit feedback (FOFB) requires shifting the fast corrector strengths to the slow correctors to prevent the fast corrector saturation and to make the beam orbit stable in the sub-micron level. As the result, a reliable and precise technique of fast-to-slow corrector strength shift has been developed and tested at NSLS-II. This technique is based on the fast corrector response to the slow corrector change when the FOFB is on. In this article, the shift technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented. The maximum fast corrector current was reduced from greater than 0.45 A to less than 0.04 A with the orbit perturbation within ±1 μm. Especially when the step size of the shift was below 0.012 A, the amount of noise being added to the beam was none.
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TUPMF036	Top Off of NSLS-II with Inefficient Injector	booster, injection, linac, storage-ring	1327
	R.P. Fliller, A.A. Derbenev, V.V. Smaluk, X. Yang BNL, Upton, Long Island, New York, USA
	Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy The NSLS-II is a 3 GeV storage with a full energy injector capable of top off injection. The injector consists of a 200 MeV linac injecting a 3 GeV booster. Recent operational events have caused us to investigate 100 MeV injection into the booster. As the booster was not designed for injection at this low energy, beam loss is observed with this low energy booster injection. This beam loss not only results of overall charge loss from the train, but a change in the overall charge distribution in the bunch train. In this paper we discuss the performance of injecting into the storage ring with the inefficient charge transfer through the injector. The changes to the top off method are discussed, as well as the achieved storage ring current stability and fill pattern.
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TUPMF037	Development of New Operational Mode for NSLS-II Injector: Low Energy 100MeV Linac-to-Booster Injection	booster, injection, klystron, linac	1330
	X. Yang, A.A. Derbenev, R.P. Fliller, T.V. Shaftan, V.V. Smaluk BNL, Upton, Long Island, New York, USA
	The NSLS-II injector consists of a 200 MeV linac and a 3 GeV full-energy booster synchrotron. The linac contains five traveling-wave S-band accelerating structures driven by two high-power klystrons, with a third klystron as spare. In the event that the spare klystron is not available, the failure of one klystron will prohibit the linac from injecting into the booster as the energy is too low. Therefore, we wish to develop a new operational mode that the NSLS-II injector can operate with a single klystron providing 100 MeV beam from the linac. A decremented approach with intermediate energies 170 MeV, 150 MeV, etc., takes advantages of pre-calculated booster ramps and beam based online optimization. By lowering the booster injection energy in a small step and online optimizing at each step, we were able to achieve 100 MeV booster injection. 170 MeV operation mode of the NSLS-II injector has been implemented since May 31, 2017, with a similar overall performance compared to the standard 200 MeV operation but fewer klystron trips. 100 MeV single-klystron operation has been successfully demonstrated with 20-30% overall efficiency, which is limited by booster acceptance.
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TUPMF080	Progress on Multibunch FEL Performance at FLASH	cavity, 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
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TUPMF090	Status of the Superconducting Soft X-Ray Free-Electron Laser FLASH at DESY	FEL, laser, undulator, electron	1481
	M. Vogt, K. Honkavaara, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, R. Treusch DESY, Hamburg, Germany
	FLASH, the free-electron laser (FEL) user facility at DESY, has delivered high brilliance VUV and soft x-ray FEL radiation for photon experiments since summer 2005. In 2014 and 2015 a second beamline, FLASH2, has been commissioned in parallel to user operation at FLASH1. FLASH's superconducting linac can produce bunch trains of up to 800 bunches within a 0.8 ms RF flat top at a repetition rate of 10 Hz. In standard operation during 2017 FLASH supplied up to 500 bunches in two bunch trains with independent fill patterns and compression schemes. Since mid 2017 initial commissioning of a third experimental beamline, accommodating the FLASHForward plasma wakefield acceleration experiment, has started. We report on the highlights of the FLASH operation in 2017/2018.
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TUPMK012	Acceleration of Charged Particles by Own Field in a Non-Stationary One-Dimensional Stream	interface, ECR, electron, acceleration	1516
	A.S. Chikhachev Allrussian Electrotechnical Institute, Moskow, Russia
	The behavior of a non-stationary stream of the charged particles interacting with own field is studied. For the description the integral of the movement received in works * - Meshchersky's integral is used. The additional integral of the movement - interfaced to Meshchersky's integral, necessary for completely self-agreed description of a stream of the particles interacting with own field is constructed. The system of the equations reducing a problem to the solution of system of the ordinary differential equations is removed. Private decisions for potential, density of particles and density of current are provided. Earlier the problem was studied in work . Mestschersky J. Astronomische Nachrichten, 1893, T.132, N3153, p. 9. Nestschersky ibid, 1902, T.159, N3807, p. 15. * Chikhachev A.S., Technical Phisics, 2014, vol 59, N 4, pp 487-493.
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TUPML014	CO2 CPA Laser Development for User Experiments in Advanced Accelerators and Radiation Sources	laser, experiment, plasma, optics	1556
	M.N. Polyanskiy, M. Babzien, M.A. Palmer, I. Pogorelsky BNL, Upton, Long Island, New York, USA
	The ATF* is a National User Facility for advanced research in accelerator physics and technology. The ATF's terawatt CO2 laser is a unique scientific instrument allowing researchers to explorer new particle acceleration mechanisms and to study light/matter interaction at an order-of-magnitude longer photon wavelengths compared to the majority of other laser research facilities (λ≈10μm). Continuous development over more than two decades brought the ATF's CO2 laser to the limit of peak power achievable in a conventional gas laser MOPA configuration (in ATF's amplifier geometry this is ~0.5 TW in routine operation, and up to 2 TW in some experiments). To overcome this limit, we employ, for the first time in a gas laser, a chirped-pulse amplification (CPA) scheme. The goal of our current research and development effort is to demonstrate 3-5 TW peak power at the system output and to reliably deliver a large fraction of this power as a high-quality beam to a range of user experiments. Achieving this goal will lay the ground work for implementation of a >10 TW mid-IR laser system "BESTIA" that is currently being constructed as a part of the ATF-II project. *Accelerator Test Facility at Brookhaven National Laboratory
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TUPML016	High-Intensity Magnetron H⁻ Ion Sources and Injector Development at BNL Linac	rfq, ion-source, injection, linac	1564
	A. Zelenski, G. Atoian, T. Lehn, D. Raparia, J. Ritter BNL, Upton, Long Island, New York, USA
	The BNL magnetron-type H⁻ ion source and the injec-tor are being upgraded to higher duty-factor as a part of Linac intensity increase project [1]. The BNL magnetron source presently delivers 110 -120 mA H⁻ ion current with 650 us pulse duration and 7 Hz repetition rate. The pulse duration was increased to 1000 μs by modifications of the gas injector pulsed valve and the use of the new arc-discharge power supply (with the arc-current stabilization circuit) which improved current stability and reduced current noise. The Low Energy Beam Transport (LEBT) lines combine two beams. The first line is the polarized OPPIS (Optically Pumped Polarized H⁻ Ion Source) beam-line and the second is the high-intensity un-polarized beam-line from the magnetron source, which transports beam to the RFQ after the passage of 45 degree bending magnet. The second magnetron source was installed in the straight LEBT section in 2017, in which the polarized OPPIS beam was not planned. In this, optimal for H⁻ beam transport configuration, the beam intensity was increased to 80 mA after the RFQ. The experience of the two sources layout operation (one source in operation the second source in standby) might be useful for facilities with the high downtime cost (like high-energy collider LHC or multi-user facilities like SNS).
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TUPML053	The BERLinPro SRF Photoinjector System - From First RF Commissioning to First Beam	cathode, cavity, SRF, 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.
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TUPML075	Development of Target/ion Source for Li-8 Beam at KOMAC*	target, ion-source, proton, vacuum	1718
	J.J. Dang, Y.-S. Cho, H.S. Kim, H.-J. Kwon, P. Lee, S. Lee, Y.G. Song Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
	Funding: This work has been supported through KOMAC operation fund of KAERI by MSIT and the NRF of Korea grant funded by the Korea government (MSIT) (No. NRF-2017M2A2A6A02071070). A target/ion source (TIS) for Li-8 isotope beam has been developed at Korea Multi-purpose Accelerator Complex (KOMAC). The TIS was designed based on various numerical studies such as Monte Carlo simulation for Li-8 yield estimation, an ionization efficiency calculation of a surface ionization ion source and thermal analysis by a power balance model. Then, it was fabricated that a prototype of the TIS which consists of a beryllium oxide (BeO) target, a graphite target container, a tantalum target heater and a rhenium surface ion source. Also, the target heater and the surface ion source were heated to designed operation temperatures. In addition, it has been designed and constructed that an online test facility including Li-8 beam optics and diagnostics.
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WEXGBD2	Pulse-by-Pulse Multi-XFEL Beamline Operation with Ultra-Short Laser Pulses	electron, FEL, optics, undulator	1740
	T. Hara, T. Inagaki, H. Maesaka, Y. Otake, H. Tanaka, K. Togawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan K. Fukami JASRI/SPring-8, Hyogo-ken, Japan T. Hasegawa, O. Morimoto, S. Nakazawa, M. Yoshioka SES, Hyogo-pref., Japan H. Kawaguchi, Y. Kawaguchi Nichicon (Kusatsu) Corporation, Shiga, Japan C. Kondo JASRI, Hyogo, Japan
	The parallel operation of multiple beamlines is an important issue to expand the opportunity of user experiments for linac based FELs. At SACLA, the parallel operation of three beamlines, BL1~3, has been open to user experiments since September 2017. BL1 is a soft x-ray beamline driven by a dedicated accelerator, which is a former SCSS linac, and BL2 and 3 are XFEL beamlines, which share the electron beam from the SACLA main linac. In the parallel operation, a kicker magnet with 10 ppm stability (peak-to-peak) switches the two XFEL beamlines at 60 Hz from pulse to pulse. To ensure wide spectral tunability and optimize the laser performance, the energies and lengths of the electron bunches are independently adjusted for the two beamlines according to user experiments. Since the electron bunch of SACLA has typically 10~15 fs (FWHM) in length and its peak current exceeds 10 kA, the CSR effect at a dogleg beam transport to BL2 is quite significant. In order to suppress the CSR effects, an isochronous and achromatic lattice based on two DBA structures was introduced. In this talk, the multiple XFEL beamline operation and achieved laser performance are presented.
	Slides WEXGBD2 [9.708 MB]
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WEXGBF1	Testing of the ESS MB-IOT Prototypes	klystron, linac, cavity, 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]
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WEYGBD1	12 GeV CEBAF Initial Operational Experience and Challenges	MMI, cryomodule, experiment, cavity	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]
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WEYGBD2	Status of the Radiation Damage on the European XFEL Undulator Systems	undulator, radiation, FEL, electron	1776
	F. Wolff-Fabris, J. Pflüger XFEL. EU, Schenefeld, Germany F. Hellberg Stockholm University, Stockholm, Sweden F. Schmidt-Föhre DESY, Hamburg, Germany
	The European XFEL GmbH is a new X-ray FEL user facility and started lasing in 2017. Three gap movable SASE Undulator Systems are designed to produce FELs with tunable wavelengths from 0.05 to 5.2nm [,]. A total of 91 5-m long undulator segments based on hybrid NdFeB permanent magnet technology were tuned respecting tight specifications. Radiation damage due to machine operation affects the magnetic properties of the segments and the quality of the SASE process. An array of dosimeters based on Radfets [*] and Gafchromic films monitors the absorbed doses in every undulator segment and each SASE system is equipped with a 12mm gap diagnostic undulator (DU) which is magnetically re-measured during machine maintenance weeks. Doses up to 4 kGy have been observed and magnetic field degradation higher than 3% is measured. These results permit to estimate the effects of radiation damage and life expectancy of the Undulator Systems based on the precise K-parameter determination for beam operation. We will present the results of magnetic re-measurements on the Undulator Systems, the details of the effects of radiation damage and future plans to maximize the beam quality and operation. M. Altarelli et al., Tech. Design Rep. DESY 2006-097, July 2007. E. Schneidmiller et al., Eur. XFEL Tech. Rep. TR-2011-006, Sep. 2011. * F. Schmidt-Föhre et al., IPAC-2018 contribution.
	Slides WEYGBD2 [3.670 MB]
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WEYGBE4	Low-Impedance Collimators for HL-LHC	impedance, octupole, collimation, luminosity	1794
	S. A. Antipov, N. Biancacci, R. Bruce, A. Mereghetti, D. Mirarchi, E. Métral, S. Redaelli, B. Salvant CERN, Geneva, Switzerland D. Amorim Université Grenoble Alpes, Grenoble, France
	The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) will double its beam intensity for the needs of High Energy Physics frontier. This increase requires a reduction of the machine's impedance to ensure the coherent stability of the beams until they are put in collision. A major part of the impedance is the resistive wall contribution of the collimators. To reduce this contribution several coating options have been proposed. We have studied numerically the effect of the novel coatings on the beam stability. The results show that a decrease of up to 30% of the machine impedance and a reduction of up to 120 A in the stabilizing octupole current threshold can be achieved by coating the secondary collimators with Molybdenum. Half of that improvement can be obtained by coating the jaws of a subset of four collimators identified as the highest contributors to machine impedance. The installation of this subset of low-impedance collimators is planned for the Long Shutdown 2 in 2019-2020.
	Slides WEYGBE4 [5.719 MB]
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WEPAF005	A Fast Beam Interlock System for the Advanced Photon Source Particle Accumulator Ring	radiation, photon, shielding, detector	1815
	J.C. Dooling, M. Borland, K.C. Harkay, R.T. Keane, B.J. Micklich, C. Yao ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Of- fice of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A fast beam interlock system for the Advanced Photon Source (APS) Particle Accumulator Ring (PAR) based on the detection of Cerenkov light is proposed for high-charge operations associated with the APS Upgrade (APS-U). Light is generated from lost electrons passing through high-purity, fused-silica fiber optic cable. The cable acts as both radiator and light pipe to a Pb-shielded photomultiplier tube. Results from a prototype installation along the PAR south wall have shown excellent sensitivity, linearity, and reproducibility after 10,000 hours of operation to date with little change in the optical transmission of the fiber. High sensitivity allows more accurate measurement of low-level loss than possible with current monitors. The radiator and detector provide a much faster response than the installed gamma or neutron detectors. A faster, more accurate response to electron loss will be important as we run with higher charge and consider operating at increased energy for APS-U. Initial calibration measurements of the prototype system with radiation monitors for various loss scenarios are discussed. Comparison of the scenarios with simulations are presented.
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WEPAF010	Fast Glitch Detection of Coupled Bunch Instabilities and Orbit Motions	feedback, vacuum, storage-ring, injection	1829
	W.X. Cheng, B. Bacha, K. Ha, Y. Li BNL, Upton, Long Island, New York, USA
	Funding: Work supported by DOE contract No: DE-SC0012704 During high current operation at NSLS-II storage ring, vertical beam size spikes have been noticed. The spikes are believed due to ion instability associates with vacuum activities localized in the ring. A new tool has been developed using gated BPM turn-by-turn (TBT) data to detect beam centroid glitches. When one turn orbit deviates outside the predefined window, a global event will be generated. This allows synchronized data acquisition of TBT beam positions around the ring. Bunch by bunch data is acquired at the same time to analyze the possible coupled bunch instabilities (CBI). Besides CBI mainly due to ion bursts, fast orbit glitches have been captured with the new tool. Sources of the glitches can be identified.
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WEPAF011	Developments of Bunch by Bunch Feedback System at NSLS-II Storage Ring	feedback, emittance, vacuum, storage-ring	1833
	W.X. Cheng, B. Bacha, Y. Li BNL, Upton, Long Island, New York, USA D. Teytelman Dimtel, San Jose, USA
	Funding: Work supported by DOE contract No: DE-SC0012704 Transverse bunch-by-bunch (BxB) feedback system has been constructed and in operation since the very beginning of NSLS-II storage ring commissioning. As the total beam current continues increasing in the past years, the system has been operating stable and reliable. Advanced BxB diagnostic functions have been developed using the system. Continuous tune measurement is realized with a diagnostic single bunch. Coupled bunch instability growth rate is able to be measured with the transient excitation. The BxB feedback system is also capable to excite a small fraction of total bunches for lattice measurement during high current operations. We present the most recent developments and operation experience on the BxB feedback system at NSLS-II.
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WEPAF017	Correction of ID-Induced Transverse Linear Coupling at NSLS-II	coupling, emittance, quadrupole, resonance	1856
	Y. Hidaka, Y. Li, T.V. Shaftan, T. Tanabe, Y. Tian, G.M. Wang BNL, Upton, Long Island, New York, USA
	Funding: The study is supported by U.S. DOE under Contract No. DE-AC02-98CH10886. Sizeable lifetime jumps have been observed sporadically since March 2016 at NSLS-II. These jumps were found to coincide with insertion device (ID) gap motions. Particularly, one of the in-vacuum undulators (IVUs) at Cell 17 was discovered to have large localized skew quadrupole component variation with gap. To allow the machine to operate stably in the low-emittance mode, a global coupling feedforward system has been recently implemented and successfully deployed. After installation of a new additional skew quadrupole, coupling compensation of this ID is now performed by a local coupling feedforward system. Furthermore, the maximum gap limit of all the existing IVUs has been decreased from 40 mm to 25 mm to limit the skew component variation during user operation.
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WEPAF022	Application of Machine Learning to Minimize Long Term Drifts in the NSLS-II Linac	klystron, linac, network, booster	1867
	R.P. Fliller, C. Gardner, P. Marino, R.S. Rainer, M. Santana, G.J. Weiner, X. Yang, E. Zeitler BNL, Upton, Long Island, New York, USA
	Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy Machine Learning has proven itself as a useful technique in a variety of applications from image recognition to playing Go. Artificial Neural Networks have certain advantages when used as a feedforward system, such as the predicted correction relies on a model built from data. This allows for the Artificial Neural Network to compensate for effects that are difficult to model such as low level RF adjustments to compensate for long term drifts. The NSLS-II linac suffers from long terms drifts from a number of sources including thermal drifts and klystron gain variations. These drifts have an effect on the injection efficiency into the booster, and if left unchecked, portions of the bunch train may not be injected into the booster, and the storage ring bunch pattern will ultimately suffer. In this paper, we discuss the application of Artificial Neural Networks to compensate for long term drifts in the NSLS-II linear accelerator. The Artificial Neural Network is implemented in python allowing for rapid development of the network. We discuss the design and training of the network, along with results of using the network in operation.
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Paper

Title

Other Keywords

Page

MOYGB1

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

klystron, electron, cavity, 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]

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MOZGBD3

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

cavity, cryomodule, HOM, radiation

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]

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MOZGBE4

Overview of Fabrication Techniques and Lessons Learned with Accelerator Vacuum Windows

vacuum, Windows, target, site

51

C.R. Ader, M.W. McGee, L.E. Nobrega, E.A. Voirin
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy.
Vacuum thin windows have been used in Fermilab's accelerators for decades and typically have been overlooked in terms of their criticality and fragility. Vacuum windows allow beam to pass through while creating a boundary between vacuum and air or high vacuum and low vacuum areas. The design of vacuum windows, including titanium and beryllium windows, will be discussed as well as fabrication, testing, and operational concerns. Failure of windows will be reviewed as well as safety approaches to mitigating failures and extending the lifetimes of vacuum windows. Various methods of calculating the strengths of vacuum windows will be explored, including FEA.

Slides MOZGBE4 [2.155 MB]

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MOZGBF1

FRIB Front End Construction and Commissioning

rfq, MMI, ECR, ion-source

58

G. Pozdeyev
FRIB, East Lansing, Michigan, USA

The Facility for Rare Isotope Beams (FRIB) is based upon the CW, SC driver linac to accelerate all the stable isotopes up to more than 200 MeV/u with a beam power of 400 kW. The front end (FE) commissioning shall start in 2017. This invited talk presents the FRIB front end design, and current status of FRIB front end commissioning, including beam properties and energy, and their relationship to FRIB operational requirements.

Slides MOZGBF1 [2.965 MB]

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MOZGBF4

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

cavity, cryomodule, 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]

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MOPMF036

FCC-ee Hybrid RF Scheme

cavity, HOM, impedance, 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.

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MOPMF040

Crossing Angle Anti-Leveling at the LHC in 2017

luminosity, proton, simulation, experiment

184

N. Karastathis, K. Fuchsberger, M. Hostettler, Y. Papaphilippou, D. Pellegrini
CERN, Geneva, Switzerland

In 2017, LHC incorporated in operation an anti-leveling procedure of adapting in steps the crossing angle of the colliding beams to increase the integrated luminosity. In this paper, we present the Dynamic Aperture simulations that were employed to identify the operational margins, and therefore define the leveling steps. The results are complemented by observations from nominal operation and projections for the 2018 operation. Additional anti-leveling techniques, investigated in dedicated machine studies are also discussed

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MOPMF041

Refining the HL-LHC Operational Settings with Inputs From Dynamic Aperture Simulations: A Progress Report

luminosity, octupole, dynamic-aperture, experiment

188

N. Karastathis, R. De Maria, S.D. Fartoukh, Y. Papaphilippou, D. Pellegrini
CERN, Geneva, Switzerland

Recent Dynamic Aperture (DA) simulations aimed at providing guidance for the latest updates of the operational scenario for the High Luminosity upgrade of the LHC. The impact of the increased chromaticity and octupole current has been assessed considering the latest updates of the optics. Additional means to improve the lifetime, such as tune optimization, have been identified and deployed. We also briefly discuss the impact of delivering high luminosity to the LHCb experiment.

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MOPMF050

LHC Operational Experience of the 6.5 TeV Proton Run with ATS Optics

luminosity, optics, emittance, proton

216

M. Pojer, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, A. Calia, G.E. Crockford, S.D. Fartoukh, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, M. Hostettler, W. Höfle, Y. Le Borgne, D. Nisbet, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli, R. Suykerbuyk, D.J. Walsh, J. Wenninger, M. Zerlauth
CERN, Geneva, Switzerland

In May 2017, the CERN Large Hadron Collider (LHC) restarted operations at 6.5 TeV using the Achromatic Telescopic Squeeze (ATS) scheme with a target beta-star of 40 cm in ATLAS and CMS. The number of bunches was progressively increased to a maximum of 2556 with emittances of 2.5 um. In August, several machine parameters had to be re-tuned to mitigate beam loss induced instabilities and maintain a steady increase of the instantaneous luminosity. The use of a novel beam type and filling pattern produced in the injectors, allowed filling the machine with very low emittance beam (1.5 um) achieving an equivalent luminosity with 1868 bunches. In September, the beta-star was further lowered to 30 cm (using, for the first time, the telescopic technique of the ATS) and the bunch intensity pushed to 1.25·10¹¹ protons. In the last 3 months of 2017, the LHC produced more than 500 pb-1 of integrated luminosity per day, delivering to each of the high luminosity experiments 50.6 fb-1, 10% above the 2017 target. A general overview of the operational aspects of the 2017 proton run will be presented.

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MOPMF052

Monitoring and Modeling of the LHC Luminosity Evolution in 2017

luminosity, emittance, experiment, monitoring

224

N. Karastathis, F. Antoniou, I. Efthymiopoulos, M. Hostettler, G. Iadarola, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, B. Salvachua
CERN, Geneva, Switzerland

In 2017, the Large Hadron Collider (LHC) restarted operation at 6.5 TeV, after an extended end-of-the-year stop, scheduled to deliver 45/fb to the two general-purpose experiments. Continuous monitoring of the key beam parameters and machine configurations that impact the delivered luminosity was introduced, providing fast feedback to operations for further optimisation. The numerical model based on simulations and use of selected machine parameters to estimate the machine luminosity was further developed. The luminosity evolution and comparisons to the model predictions is presented in this paper. The impact of the dynamic variation of the crossing angle, which was incorporated into nominal LHC operation, is also discussed.

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MOPMF053

Observations, Analysis and Mitigation of Recurrent LHC Beam Dumps Caused by Fast Losses in Arc Half-Cell 16L2

MMI, electron, vacuum, solenoid

228

J.M. Jimenez, D. Amorim, S. A. Antipov, G. Arduini, A. Bertarelli, N. Biancacci, B. Bradu, E. Bravin, G. Bregliozzi, K. Brodzinski, R. Bruce, X. Buffat, L.R. Carver, P. Chiggiato, S.D. Claudet, P. Collier, R. Garcia Alia, M. Giovannozzi, L. K. Grob, E.B. Holzer, W. Höfle, G. Iadarola, G. Kotzian, A. Lechner, T.E. Levens, B. Lindstrom, T. Medvedeva, A. Milanese, D. Mirarchi, E. Métral, D. Perini, S. Redaelli, G. Rumolo, B. Salvant, R. Schmidt, M. Valette, D. Valuch, J. Wenninger, D. Wollmann, C. Yin Vallgren, C. Zamantzas, M. Zerlauth
CERN, Geneva, Switzerland
D. Amorim
Université Grenoble Alpes, Grenoble, France
A.A. Gorzawski
University of Manchester, Manchester, United Kingdom
L. Mether
EPFL, Lausanne, Switzerland

Recurrent beam dumps significantly perturbed the operation of the CERN LHC in the summer months of 2017, especially in August. These unexpected beam dumps were triggered by fast beam losses that built up in the cryogenic beam vacuum at the half-cell 16 left of LHC-IP2 and were detected either at that location but mainly in the collimation insertions. This contribution details the experimental observables (beam losses, coherent instabilities, heat load to cryogenic system, vacuum signals), the extent of the understanding of the beam loss and instability mechanisms and the mitigation steps and new settings that allowed recovering the luminosity performance of the LHC for the rest of the Run.

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MOPMF056

The Second LHC Long Shutdown (LS2) for the Superconducting Magnets

dipole, hadron, superconducting-magnet, collider

240

J.Ph. G. L. Tock, M. Bednarek, L. Bottura, E. Karentzos, S.L.N. Le Naour, F. Meuter, M. Pojer, C.E. Scheuerlein, E. Todesco, D. Tommasini, L. X. Van Den Boogaard, G.P. Willering
CERN, Geneva, Switzerland

The Large Hadron Collider (LHC) has been delivering data to the physics experiments since 2009. It first operated at a centre of mass energy of 7 TeV and 8 TeV up to the first long shutdown (LS1) in 2013-14. The 13 kA splices between the main LHC cryomagnets were consolidated during LS1. Then, it was possible to increase safely the centre of mass energy to 13 TeV. During the training campaigns, metallic debris caused short circuits in the dipole diode containers, leading to an unacceptable risk. Major interventions can only take place during multiyear shutdowns. To ensure safe operation at higher energies, hence requiring further magnets training, the electrical insulation of the 1232 dipole diodes bus-bars will be consolidated during the second LHC long shutdown (LS2) in 2019-20. The design of the reinforced electrical insulation of the dipole cold diodes and the associated project organisation are presented, including the validation tests, especially at cryogenics temperature. During LS2, maintenance interventions on the LHC cryomagnets will also be performed, following the plan based on a statistical analysis of the electrical faults. It is inscribed in the overall strategy to produce collisions at 14 TeV, the LHC design energy, and to push it further towards 15 TeV. We give a first guess on the impact on the LHC failure rate.

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MOPMF062

Upgrade of the Dilution System for HL-LHC

kicker, Windows, damping, simulation

261

C. Wiesner, W. Bartmann, C. Bracco, M. Calviani, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, S.S. Gilardoni, B. Goddard, T. Kramer, A. Lechner, N. Magnin, A. Perillo-Marcone, T. Polzin, E. Renner, V. Senaj
CERN, Geneva, Switzerland

The LHC Beam Dump System is one of the most critical systems for reliable and safe operation of the LHC. A dedicated dilution system is required to sweep the beam over the front face of the graphite dump core in order to reduce the deposited energy density. The High Luminosity Large Hadron Collider (HL-LHC) project foresees to increase the total beam intensity in the ring by nearly a factor of two, resulting in a correspondingly higher energy deposition in the dump core. In this paper, the beam sweep pattern and energy deposition for the case of normal dilution as well as for the relevant failure cases are presented. The implications as well as possible mitigations and upgrade measures for the dilution system, such as decreasing the pulse-generator voltage, adding two additional kickers, and implementing a retrigger system, are discussed.

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MOPMF063

Asynchronous Beam Dump Tests at LHC

proton, extraction, beam-losses, quadrupole

265

C. Wiesner, W. Bartmann, C. Bracco, E. Carlier, L. Ducimetière, M.I. Frankl, M.A. Fraser, B. Goddard, C. Heßler, T. Kramer, A. Lechner, N. Magnin, V. Senaj, D. Wollmann
CERN, Geneva, Switzerland

The detailed understanding of the beam-loss pattern in case of an asynchronous beam dump is essential for the safe operation of the future High Luminosity LHC (HL-LHC) with nearly twice the nominal LHC beam intensity, leading to correspondingly higher energy deposition on the protection elements. An asynchronous beam dump is provoked when the rise time of the extraction kickers is not synchronized to the 3 us long particle-free abort gap. Thus, particles that are not absorbed by dedicated protection elements can be lost on the machine aperture. Since asynchronous beam dumps are among the most critical failure cases of the LHC, experimental tests at low intensity are performed routinely. This paper reviews recent asynchronous beam dump tests performed in the LHC. It describes the test conditions, discusses the beam-loss behaviour and presents simulation and measurement results. In particular, it examines a test event from May 2016, which led to the quench of four superconducting magnets in the extraction region and which was studied by a dedicated beam experiment in December 2017.

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MOPML009

New High Luminosity LHC Baseline and Performance at Ultimate Energy

luminosity, optics, emittance, cavity

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

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MOPML024

Implementation of a Non-Invasive Online Beam Monitor at a 60 MeV Proton Therapy Beamline

detector, proton, cyclotron, monitoring

449

R. Schnuerer, C.P. Welsch, S.L. Yap, H.D. Zhang
Cockcroft Institute, Warrington, Cheshire, United Kingdom
O. Girard, G.J. Haefeli
EPFL, Lausanne, Switzerland
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

To fully exploit the advantageous dose distribution profiles of ion radiotherapy, an exact knowledge of the beam properties through online beam monitoring is essential, ensuring thus an effective dose delivery to the patient. One potential candidate for an online beam monitor is the LHCb Vertex Locator (VELO). This detector, originally developed for the LHCb experiment, has been adapted to the specific conditions of the clinical environment in a proton therapy centre. The semicircular design and position of its sensitive silicon detector offers a non-invasive way to measure the beam intensity without interfering with the beam core. In this contribution, modifications for VELO are described. The detector is synchronized with the readout of a locally-constructed Faraday Cup and the 25.7 MHz RF frequency of the cyclotron at the Clatterbridge Cancer Centre (CCC). Geant4 Monte Carlo simulations investigate the integration of the detector in the treatment line and behaviour of the beam during delivery. The capability of VELO as a beam monitor will be assessed by measuring the beam current and by monitoring the beam profile along the beamline this summer.

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MOPML031

Highlights of Accelerator Activities in France on Behalf of the Accelerator Division of the French Physics Society

linac, laser, proton, electron

470

J.-L. Revol
ESRF, Grenoble, France
S. Chel
CEA/IRFU, Gif-sur-Yvette, France
B. Cros
CNRS LPGP Univ Paris Sud, Orsay, France
N. Delerue
LAL, Orsay, France
E. Giguet
ALSYOM, Versailles, France
V. Le Flanchec
CEA/DAM, Bruyères-le-Châtel, France
L.S. Nadolski
SOLEIL, Gif-sur-Yvette, France
L. Perrot
IPN, Orsay, France
A. Savalle
GANIL, Caen, France
T. Thuillier
LPSC, Grenoble Cedex, France

The French Physical Society is a non-profit organization working to advance and diffuse the knowledge of physics. Its Accelerators division contributes to the promotion of accelerator activities in France. This paper presents the missions and actions of the division, high-lighting those concerning young scientists. A brief presentation of the laboratories, institutes, and facilities that are the main actors in the field is given. Significant ongoing and planned projects in France are described, including medical applications. Main French contributions in inter-national projects are then listed. Finally, cultural and technical relationships between industry and laboratories are discussed.

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MOPML033

Data Supply of Accelerator Devices - Data Management of Device Process Data at a Medical Accelerator

controls, database, MMI, linac

477

M. Galonska, R. Cee, Th. Haberer, K. Höppner, J.M. Mosthaf, A. Peters, S. Scheloske, C. Schömers
HIT, Heidelberg, Germany

HIT is the first dedicated proton and carbon cancer therapy facility in Europe. It uses the full 3D intensity controlled raster scanning dose delivery method of pencil beams with ion beams of 48 - 430 MeV/u provided by a linac-synchrotron-system. Ion beams in this wide range of energies, different beam sizes, and intensities have to be provided by the control system to all treatment rooms at any time with high accuracy, stability, and reproducibility. This paper briefly reflects some aspects of the data supply, i. e. the settings of accelerator devices at a medical accelerator. This includes the generation of control data, storage, and data recovery routines, which have been developed at HIT in the recent years. That is in particular the management of verified therapy data and settings, which are stored in a non-volatile memory of the device controllers, and – as a backup – in a database and which are protected against unintended changes for safety reasons.

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MOPML048

Design Study of PM Dipole for ILC Damping Ring

dipole, permanent-magnet, damping, radiation

505

Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
N. Terunuma
KEK, Ibaraki, Japan

Dipole magnet using permanent magnet technology is under investigation for ILC cost reduction. It can reduce cost of electricity of coil excitation and cooling water pump, thick electric cabling and water piping, power supply, and their maintenance cost. The structure and the field adjustment scheme will be discussed.

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MOPML053

Mu*STAR Accelerator-Driven Subcritical Reactors Burning Spent Nuclear Fuel at Light-Water-Reactor Sites

target, site, neutron, SRF

524

R.P. Johnson, R.J. Abrams, M.A. Cummings, T.J. Roberts
Muons, Inc, Illinois, USA

This project will use modeling and simulation tools to optimize many aspects of the Mu*STAR design and begin to explore accident scenarios. At present we have a conceptual design of the accelerator, the reactor, the spallation target, and the fractional distillation to separate volatile fission products. Our GAIN project with ORNL is preparing a design of the Fuel Processing Plant that will convert spent nuclear fuel into the molten-salt fuel for Mu*STAR. This includes all of the nuclear components, but not such things as the turbine and generator, physical plant, control and monitoring systems, etc. We currently have basic simulations of the reactor neutronics, and a start at calculating the fuel evolution. These have used MCNP and ORIGEN, and initial results have been reported1. This project will support the use of additional neutronics and multi-physics codes, enabling a much more thorough analysis of the system.

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TUXGBD2

Colliding Heavy Ions in the LHC

luminosity, heavy-ion, experiment, proton

584

J.M. Jowett
CERN, Geneva, Switzerland

The Large Hadron Collider at CERN not only collides protons but also heavier nuclei. So far Pb+Pb, Xe-Xe and p+Pb collisions, at multiple energies, have been provided for what was initially conceived as a distinct physics program on the collective behavior of QCD matter at extreme energy density and temperature. However unexpected phenomena observed in p+Pb and p+p collisions at equivalent energies have blurred the distinction. Intense, low-emittance, ion beams are provided by a dedicated source and injector chain setup. When Pb beams collide, new luminosity limits arise from photon-photon and photonuclear interactions but effective mitigations have allowed luminosities over 3 times design. Asymmetric p+Pb collisions introduce new features and beam-dynamical phenomena into operation of the LHC but have also achieved luminosity far beyond expectations. With experimental requirements for multiple changes in energy and data-taking configurations during very short heavy-ion runs, high operational efficiency and reliability are vital. This invited talk discusses performance, future prospects, and technical challenges for the LHC heavy ion program, including injector performance.

Slides TUXGBD2 [5.317 MB]

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TUYGBD2

A Review of DAΦNE Performances During the KLOE-2 Run

luminosity, detector, vacuum, collider

624

C. Milardi, D. Alesini, S. Bini, O.R. Blanco-García, M. Boscolo, B. Buonomo, S. Cantarella, S. Caschera, A. D'Uffizi, A. De Santis, G.O. Delle Monache, D.G.C. Di Giulio, G. Di Pirro, A. Drago, L.G. Foggetta, A. Gallo, R. Gargana, A. Ghigo, S. Guiducci, C. Ligi, M. Maestri, A. Michelotti, L. Pellegrino, R. Ricci, U. Rotundo, A. Stecchi, A. Stella, M. Zobov
INFN/LNF, Frascati (Roma), Italy

DAΦNE, the Frascati electron-positron accelerator complex, has almost completed the last and more chanlleging period of operation for the KLOE-2 detector. In this context the performances of the collider, based on the Crab-Waist collision scheme, are reviewed and the limiting factors discussed.

Slides TUYGBD2 [9.928 MB]

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TUPAF001

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

linac, cryogenics, cavity, cryomodule

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.

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TUPAF012

Commissioning of the Lipac Medium Energy Beam Transport Line

cavity, vacuum, rfq, controls

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).

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TUPAF023

The Beamlines of the CERN East Area Renovation Project

target, secondary-beams, radiation, experiment

717

J. Bernhard, M. Bonnet, Q. Bouirek, D. Brethoux, B.D. Carlsen, A. Ebn Rahmoun, J. Etheridge, S. Evrard, L. Gatignon, E. Harrouch, M. Lazzaroni, M. Van Dijk, A. Watrigant
CERN, Geneva, Switzerland

The East Area at the Proton Synchrotron is one of CERN's longest running facilities for experiments, beam tests, and irradiations with a successful history of over 55 years. The facility serves more than 20 user teams for about 200 days of running each year and offers mixed secondary hadron, electron and muon beams of 0.5 GeV/c to 10 GeV/c. In addition, the primary proton beam or ion beam is transported to the irradiation facilities CHARM and IRRAD. Due to the steadily high user demand, the CERN management approved an upgrade and renovation of the facility to meet future beam test and physics requirements. New beam optics will assure a better transmission and purity of the secondary beams, now also with the possibility of highly pure electron, hadron or muon beams. The upgrade includes a pulsed powering scheme with energy recovering power supplies and new magnets, reducing both power and cooling requirements. Together with the building consolidation, this results in a considerably lower energy consumption. The renovation phase is scheduled during the technical stops between 2018 and 2020. We will give an overview of the project scope including upgrades and future beams.

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TUPAF025

Multi-turn Study in FLUKA for the Design of CERN-PS Internal Beam Dumps

dumping, simulation, experiment, proton

724

J.A. Briz Monago, M. Calviani, F. Cerutti, J.J. Esala, S.S. Gilardoni, F.-X. Nuiry, G. Romagnoli, G. Sterbini, V. Vlachoudis
CERN, Geneva, Switzerland

The CERN Proton-Synchrotron (PS) accelerator is currently equipped with two internal beam dumps in operation since the 1970's. An upgrade is required to be able to withstand the beams that will be produced after the end of the LIU (LHC Injector Upgrade) project. For the design of the new dumps, the interaction and transport of beam and all secondary particles generated has been simulated using FLUKA. The working principle of the internal beam dump in the PS ring is very peculiar with respect to the other dumps in the CERN accelerator complex. A moving dump intercepts the circulating beam during few milliseconds like a fast scraper. The moving dump shaving the beam, the multi-turn transport of beam particles in the PS accelerator and a time-dependent energy deposition in the dump were modeled. The methodology and the results obtained in our studies for the dump core and downstream equipment will be reported in this contribution.

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TUPAF029

Observation of Fast Losses in the LHC Operation in 2017

detector, betatron, beam-losses, monitoring

740

A.A. Gorzawski, N. Fuster-Martínez, S. Redaelli, C. Xu, C. Zamantzas
CERN, Geneva, Switzerland
R.B. Appleby
UMAN, Manchester, United Kingdom
H. Garcia Morales
Royal Holloway, University of London, Surrey, United Kingdom

Four diamond detectors that provide beam loss measurements with time resolution in the nanosecond range were added in the vicinity of the primary collimators of the Large Hadron Collider (LHC). This is a powerful diagnostic tool that provides the unique chance to measure bunch-by-bunch losses. The operation of the LHC in 2017 presented several unusual events of fast, high intensity beam losses, many of them captured by the diamond detectors in the betatron cleaning region. In this paper we review some of the relevant loss cases that were analyzed in the wider scope of determining the source of the instability generating these losses. We show few of the possible applications of this detectors in daily operations.

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TUPAF031

Beam Simulation Studies for the Upgrade of the SPS Beam Dumping System

kicker, simulation, dumping, injection

747

C. Heßler, W. Bartmann, E. Carlier, L. Ducimetière, B. Goddard, F.M. Velotti
CERN, Geneva, Switzerland

The SPS at CERN currently uses a beam dumping system that is installed in the long straight section 1 (LSS1) of the SPS. This system consists of two beam stopper blocks for low and high energy beams, as well as two vertical and three horizontal kicker magnets, which deflect and dilute the beam on the dumps. Within the frame of the LHC injector upgrade project (LIU) the beam dumping system will be relocated to long straight section 5 (LSS5) and upgraded with an additional vertical kicker, new main switches and a single new beam dump, which covers the full energy range. The impact of a possible increase of the vertical kicker rise time on the beam has been studied in simulations with MAD-X for the different optics in the SPS. Furthermore, the impact on the beam in failure scenarios such as the non-firing of one kicker has been investigated. The results of these studies will be presented and discussed in this paper. Operational mitigation methods to deal with an increased rise time will also be discussed.

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TUPAF038

Prototyping Activities for a New Design of CERN's Antiproton Production Target

target, proton, experiment, antiproton

772

C. Torregrosa, M.E.J. Butcher, M. Calviani, J.P.C. Espadanal, R. Ferriere, L. Gentini, E. Grenier-Boley, L. Mircea Grec, A. Perillo-Marcone, R. Seidenbinder, N.S. Solieri, M.A. Timmins, E. Urrutia, V. Vlachoudis
CERN, Geneva, Switzerland

Antiprotons are produced at CERN by impacting intense proton beams of 26 GeV/c onto a high-Z water-cooled target. The current design consists in an Ir core target in a graphite matrix and inserted in a Ti-6Al-4V assembly. A new target design has been foreseen for operation after 2021 aiming at improving the operation robustness and antiproton production yield, triggering several R&D activities during the last years. First, both numerical (use of hydrocodes) and experimental approaches were carried out to study the core material response under extreme dynamic loading when impacted by the primary proton beam. The lessons learnt from these studies have been then applied to further prototyping and testing under proton beam impact at the CERN-HiRadMat facility. A first scaled prototype consisting in Ta rods embedded in an expanded graphite matrix was irradiated in 2017, while in 2018, the PROTAD experiment will test different real-scale AD-Target prototypes, in which the old water-cooled assembly is replaced by a more compact air-cooled one, and different core geometry and material configurations are investigated. This contribution details these prototyping and testing activities.

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TUPAF040

Beam Loss Measurements for Recurring Fast Loss Events During 2017 LHC Operation Possibly Caused by Macroparticles

proton, simulation, dipole, insertion

780

A. Lechner, B. Auchmann, E. Bravin, A.A. Gorzawski, L. K. Grob, E.B. Holzer, B. Lindstrom, T. Medvedeva, D. Mirarchi, R. Schmidt, M. Valette, D. Wollmann
CERN, Geneva, Switzerland

The availability of the LHC machine was adversely affected in 2017 by tens of beam aborts provoked by frequent loss events in one standard arc cell (16L2). In most of the cases, the dumps were triggered by concurrently developing fast beam instabilities leading to particle losses in the betatron cleaning insertion. Many of the events started with a distinct sub-millisecond loss peak comparable to regular dust particle events, which have been observed along all the LHC since the start-up. In contrast to regular dust events, persistent losses developed in cell 16L2 after the initial peaks which can possibly be explained by a phase transition of macroparticles to the gas phase. In this paper, we summarize the observed loss characteristics such as spatial loss pattern and time profiles measured by Beam Loss Monitors (ionization chambers). Based on the measurements, we estimate the energy deposition in macroparticles and reconstruct proton loss rates as well as the gas densities after the phase transition. Differences between regular dust events and events in 16L2 are highlighted and the ability to induce magnet quenches is discussed.

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TUPAF049

Analysis of Loss Signatures of Unidentified Falling Objects in the LHC

proton, beam-losses, vacuum, electron

814

L. K. Grob, M. Dziadosz, E.B. Holzer, A. Lechner, B. Lindstrom, R. Schmidt, D. Wollmann, C. Zamantzas
CERN, Geneva, Switzerland

Particulates in the LHC beam pipes can interact with the proton beams and cause significant beam losses. The "UFOs" (unidentified falling objects) hypothesis describes a particle falling into the beam, creating particle showers, being ionized and repelled. Though the signals of the beam loss monitors support this, many aspects remain unknown. Neither the source of the dust nor the release mechanism from the beam pipe are understood. The same holds for the forces involved in the interaction and the observed UFO rate reduction over the years. These open questions are approached from different angles. Firstly, a new data analysis tool was established featuring advanced raw data selection and statistical analysis. Results of this analysis will be presented. Secondly, dust samples were extracted from LHC components and analyzed to gain insight into the size distribution and material composition of the contamination. The performed observations and analysis lead to a better modelling of the UFO events and helped to understand the physics involved. The validated UFO models will be crucial in view of the high luminosity upgrade of the LHC (HL-LHC) and the Future Circular Collider (FCC).

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TUPAF052

Effects of Electrostatic Septum Alignment on Particle Loss During Slow Extraction at CERN SPS

alignment, extraction, simulation, septum

826

J. Prieto, Y. Dutheil, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel, F.M. Velotti
CERN, Geneva, Switzerland
M.A. Kagan
SLAC, Menlo Park, California, USA

Slow extraction is an intrinsically lossy process that splits the beam with an electrostatic septum (ES), employing a thin-wire array to delimit the high electric field region that deflects the beam into the extraction channel. At CERN's Super Proton Synchrotron (SPS) the ES is over 16 m long and composed of 5 separate units containing separate wire-arrays that can be moved independently. The tanks are all mounted on a single support structure that can move the ensemble coherently. As a result, the large number of positional degrees of freedom complicates the alignment procedure in operation. Obtaining and maintaining accurate alignment of the ES with the beam is therefore crucial for minimising beam loss. In this paper, we investigate the alignment procedure for different operational scenarios using particle tracking simulations to understand the beam loss along the extraction straight as a function of the relative positions of each of the 5 separate ES units. An important aspect of the study was to understand the required alignment tolerance to achieve optimum extraction efficiency for a given configuration of wire-array thicknesses.

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TUPAF054

Slow Extraction Efficiency Measurements at the CERN SPS

extraction, proton, septum, simulation

834

M.A. Fraser, K. Cornelis, L.S. Esposito, B. Goddard, V. Kain, F. Roncarolo, L.S. Stoel, F.M. Velotti
CERN, Geneva, Switzerland

The high efficiency of most slow extraction systems makes quantifying the exact amount of beam lost in the process extremely challenging. This is compounded by the lack of time structure in the extracted beam, as is typically required by the high-energy physics experiments, and the difficulty in accurately calibrating D.C. intensity monitors in the extraction line at count rates of ~ 10¹³ Hz. As a result, it is common for the extraction inefficiency to be measured by calibrating the beam loss signal induced by the slow extraction process itself. In this paper, measurements of the extraction efficiency performed at the CERN Super Proton Synchrotron for the third-integer resonant slow extraction of 400 GeV protons over recent years will be presented and compared to expectation from simulation. The technique employed will be discussed along with its limitations and an outlook towards a future online extraction efficiency monitoring system will be given.

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TUPAF057

The SPS Tests of the HL-LHC Crab Cavities

cavity, cryomodule, vacuum, HOM

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.

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TUPAF062

Parametric Study of the Beam Footprint Characteristics on the ESS Target

target, linac, HOM, ion-source

866

R. Miyamoto
ESS, Lund, Sweden
H.D. Thomsen
ISA, Aarhus, Denmark

The beam delivery system of the ESS linac utilizes fast oscillating triangular wave dipole magnets of two transverse planes (raster magnets) to spray each long beam pulse (2.86 ms) over a rectangular cross-check pattern on the target. The characteristics of this beam footprint on the target are determined by the amplitudes of the raster magnets, RMS sizes of the beam and, in some case, the tail of the beam profile and have to satisfy the requirements from the target for the peak density as well as the fraction outside of a given rectangular boundary. This paper presents approximate closed-form expressions for the characteristics of the beam footprint and, based on the presented expressions, explores the parameter space of the raster magnets and beam parameters for achieving the optimal characteristics of the beam footprint.

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TUPAF080

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

cavity, DTL, quadrupole, 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.

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TUPAF085

Status of Link Existing Facility Project for FAIR

linac, shielding, radiation, synchrotron

934

J. Stadlmann, C. Omet, A. Schuhmann, P.J. Spiller
GSI, Darmstadt, Germany

The project "Link existing Facility", or GaF (GSI Anbindung an FAIR), is an important subproject of the overall FAIR facility. In order to serve as injector for SIS100, the main accelerator of FAIR, the existing GSI synchrotron SIS18 is undergoing an upgrade program leading to about 100 times higher beam intensities. Especially the foreseen operation with 4 GeV Protons with up to 5·10¹² protons per second increases the radiation protection requirements to such an extent that the existing radiation protection measures are no longer sufficient. The project consists of 78 individual measures. The four most substantial activities are the construction of a table-like structure to carry additional shielding. The creation of an opening and a first part of transfer tunnel for the beamlines towards the future FAIR campus. The preparation for the building, beam dump and connection of the FAIR proton injector. The incorporation of state-of-the-art radiation- and fire-protection measures into the present facilities including the a new technical building to house technical infrastructure. We report on the project status which is foreseen to finish mid-2018.

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TUPAF086

Adaption of the HSI -RFQ Rf-Properties to an Improved Beam Dynamics Layout

simulation, rfq, linac, resonance

938

M. Vossberg, L. Groening, S. Mickat, H. Vormann, C. Xiao
GSI, Darmstadt, Germany
V. Bencini, J.M. Garland, J.-B. Lallement, A.M. Lombardi
CERN, Geneva, Switzerland

The GSI accelerator facility comprising the linear accelerator UNILAC and the synchrotron SIS18 will be used in future mainly as the injector for the Facility for Anti-Proton and Ion Research (FAIR) being under construction. FAIR requires high beam brilliance and the UNILAC's RFQ electrodes must be upgraded with respect to their beam dynamics design. The new layout is currently being conducted at CERN with the aim of adjusting the electrode voltage according to the design voltage of 123 kV. CST simulations performed at GSI assure that the resonance frequency with the new electrode geometry is recuperated through corrections of the carrier rings. Simulations on the frequency dependence of the rings shapes and their impact on the voltage distribution along the RFQ are presented.

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TUPAK001

Progress of the Modulated 325 MHz Ladder RFQ

rfq, linac, proton, quadrupole

952

M. Schuett, U. Ratzinger, M. Syha
IAP, Frankfurt am Main, Germany

Funding: BMBF 05P15RFRBA
Based on the positive results of the unmodulated 325 MHz Ladder-RFQ prototype from 2013 to 2016, we developed and designed a modulated 3.3 m Ladder-RFQ*. The unmodulated Ladder-RFQ features a very constant voltage along the axis. It accepted 3 times the operating power of which is needed in operation**. That level corresponds to a Kilpatrick factor of 3.1 with a pulse length of 200 μs. The 325 MHz RFQ is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the proton linac within the FAIR project. This particular high frequency creates difficulties for a 4-ROD type RFQ, which triggered the development of a Ladder RFQ with its high symmetry. The results of the unmodulated prototype have shown, that the Ladder-RFQ is a suitable candidate for that frequency. The duty cycle is suitable up to 5%. The basic design and tendering of the RFQ has been successfully completed in 2016. Manufacturing will be completed in May 2018. We will show the latest results of manufacturing, beam dynamics simulations for the matching between LEBT and RFQ.
*Journal of Physics: Conf. Series 874 (2017) 012048
**Proceedings of LINAC2016, East Lansing, TUPLR053

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TUPAK005

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

experiment, injection, proton, cavity

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.

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TUPAK010

The Development of a New Low Field Septum Magnet System for Fast Extraction in Main Ring of J-PARC

septum, power-supply, controls, feedback

981

T. Shibata, K. Ishii, H. Matsumoto, T. Sugimoto
KEK, Ibaraki, Japan
K. Fan
HUST, Wuhan, People's Republic of China

The J-PARC Main Ring (MR) is being upgraded to improve its beam power to the design goal of 750 kW. One important way is to reduce the repetition period from 2.48 s to 1.3 s so that the beam power can be nearly doubled. We need to improve the septum magnets for fast extraction. We are improving the magnets and their power supplies. The present magnets which are conventional type have problem in durability of septum coil by its vibration, and large leakage field at the flange of the beam duct. The new magnets are eddy current type. The eddy current type does not have septum coil, but has a thin plate. We expect that there is no problem in durability, we can construct the thin septum plate, the leakage field can be reduced. The output of the present power supply are pattern current which of flat top is 10 ms width, the new one is short pulse which of one is 10 us. The short pulse consists of 1st and 3rd higher harmonic. We can expect that the flatness and reproducibility of flat top current can be improved. The calorific power can be also reduced. This paper will report the performance of the power supply and its magnetic field with the eddy septum magnet systems.

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TUPAK011

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

proton, cavity, power-supply, 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.

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TUPAK012

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

cavity, acceleration, 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.

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TUPAL011

Low Power Test and Tuning of the LEAF RFQ

rfq, quadrupole, cavity, dipole

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.

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TUPAL017

Performance and Status of the J-PARC Accelerators

target, linac, ion-source, status

1038

K. Hasegawa, N. Hayashi, M. Kinsho, H. Oguri, K. Yamamoto, Y. Yamazaki
JAEA/J-PARC, Tokai-mura, Japan
T. Koseki, F. Naito, M. Yoshii
KEK, Tokai, Ibaraki, Japan
N. Yamamoto
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

The J-PARC is a high intensity proton facility and the accelerator consists of a 400 MeV linac, a 3 GeV Rapid Cycling Synchrotron (RCS) and a 30 GeV Main Ring Synchrotron (MR). Regarding 3 GeV beam from the RCS, we delivered it at 150 kW to the materials and life science experimental facility (MLF), for the neutron and muon users. The beam powers for the neutrino experiment at 30 GeV was 420 kW in May 2016, but increased to 470 kW in February 2017 thanks to the change and optimization of operation parameters. For the hadron experimental facility which uses a slow beam extraction mode at 30 GeV, we delivered beam at a power of 37 kW, after the recovery from a trouble at an electro static septum. We have experienced many failures and troubles to impede full potential and high availability. In this report, operational performance and status of the J-PARC accelerators are presented.

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TUPAL018

Pulse-by-Pulse Switching of Operational Parameters in J-PARC 3-GeV RCS

emittance, injection, extraction, betatron

1041

H. Hotchi, H. Harada, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, Y. Watanabe, M. Yoshimoto
JAEA/J-PARC, Tokai-mura, Japan

J-PARC 3-GeV RCS (rapid cycling synchrotron) provides a high-power beam both to MLF (materials and life science experimental facility) and MR (main ring synchrotron) by switching the beam destination pulse by pulse. The beam properties required from MLF and MR are different; MLF needs a wide-emittance beam with less charge density, while MR requires a low-emittance beam with less beam halo. To meet the antithetic requirements while keeping beam loss at permissible levels, RCS has recently initiated pulse-by-pulse switching of operational parameters (betatron tune, chromaticity, painting emittance, etc.). This paper presents the recent efforts toward the performance upgrade of RCS while discussing the related beam dynamics issues.

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TUPAL020

Recent Status of J-PARC Rapid Cycling Synchrotron

injection, target, emittance, proton

1045

K. Yamamoto, P.K. Saha
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The 3 GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) provides more than 300 kW beam to the Material and Life Science Facility (MLF) and the Main Ring (MR). In such high intensity hadron accelerator, the lost protons that are a fraction of the beam less than 0.1 % cause many problems. Those particles bring about a serious radioactivation and a malfunction of the accelerator components. Therefore, we carried out the beam study to achieve high power beam operation. Moreover, we also maintain the accelerator components to keep a steady operation. We report present status of the J-PARC RCS.

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TUPAL029

Harmonictron

acceleration, cavity, proton, 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.

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TUPAL034

Effect of 805-MHz Linac RF Stability on Beam Losses in LANSCE High-Energy Beamlines

beam-losses, linac, neutron, proton

1078

Y.K. Batygin
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.
Operation of an accelerator facility critically depends on stability of the field amplitudes and phases of the accelerating cavities. The LANSCE linear accelerator consists of a 201.25-MHz, drift-tube linac and an 805-MHz, side-coupled-cavity linac (SCL). Beam losses in the high-energy beamlines of the 800-MeV facility were measured versus variation of the amplitudes and phases of the 805-MHz, SCL, RF cavities. A recent study* confirms that to achieve low losses, the stability of the amplitudes and phases should be kept within 0.1% and 0.1o, respectively. This agrees with a previous study of beam losses in the 201.25-MHz linac. Details of the measurements and results are presented.
*L.J.Rybarcyk, R.C.McCrady, Proceeding of LINAC2016, East Lansing, MI, USA, MOPLR072, p.301.

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TUPAL045

Towards Operational Scalability for H⁻ Laser Assisted Charge Exchange

laser, experiment, cavity, 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.

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TUPAL046

Construction, Test, and Operation of a new RFQ at the Spallation Neutron Source (SNS)

rfq, linac, ion-source, vacuum

1113

Y.W. Kang, A.V. Aleksandrov, W.E. Barnett, M.S. Champion, M.T. Crofford, B. Han, S.W. Lee, J. Moss, R.T. Roseberry, J.P. Schubert, A.P. Shishlo, M.P. Stockli, C.M. Stone, R.F. Welton, D.C. Williams, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA
C.C. Peters, J. Price
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: * This work was supported by SNS through UT-Battelle, LLC, under contract DEAC0500OR22725 for the U.S. DOE.
A new RFQ was successfully installed recently in the SNS linac to replace the old RFQ that was used for more than a decade with certain operational limitations. The new RFQ was completely tested with H⁻ ion source in the Beam Test Facility (BTF) at SNS. For robust operation of SNS at 1.4 MW, the full design beam power and to satisfy the beam current requirement of the forthcoming SNS proton power upgrade (PPU) project, an RFQ with enhanced performance and reliability was needed. The new RFQ was built to have the beam parameters identical to those of the first RFQ but with improved RF and mechanical stability and reliability for continuous operation of neutron production. The tests confirmed that the new RFQ can run with high beam transmission efficiency at around 90 % and notably improved operational stability. In this paper, construction, test, installation, and operation of the new RFQ in SNS are discussed with the performance improvements.

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TUPAL052

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

DTL, cavity, neutron, linac

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.

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TUPAL055

Progress with Carbon Stripping Foils at ISIS

synchrotron, vacuum, injection, proton

1136

B. Jones, H.V. Cavanagh
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The ISIS Facility at the Rutherford Appleton Laboratory produces intense neutron and muon beams for condensed matter research. The facility's 50Hz rapid cycling synchrotron accelerates protons from 70 to 800MeV to deliver a mean beam power of 0.2MW to two target stations. Since 2016, ISIS has routinely used commercially produced carbon based foils for beam stripping during charge-exchange injection. Recent experience and developments to increase useful foil lifetime are presented including in-house high temperature annealing of foils prior to use. The installation and performance of a new foil imaging system are described and, finally, the procedure to change the stripping foil is described. Issues with the current arrangements and options for redesign are discussed.

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TUPAL057

Preliminary Experiments in Caesium Delivery and Gettering on the ISIS Vespa Source

experiment, ion-source, plasma, site

1144

T. M. Sarmento, R.E. Abel, D.C. Faircloth, S.R. Lawrie, J.H. Macgregor, M. Whitehead, T. Wood
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

Caesium capture by graphite at various temperatures 20- 300°C in the VESPA ion source test stand was explored in a preliminary experiment. An accompanying experiment was set up to evaluate the control of caesium boiler delivery in the various ISIS penning sources. Results indicate Cs flux fluctuates at constant settings, which must be accounted for to interpret graphite gettering results. Future studies to identify the cause of fluctuations are considered, and a more rigorous experiment to study the use of graphite is introduced.

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TUZGBE2

Final-focus Superconducting Magnets for SuperKEKB

solenoid, quadrupole, MMI, detector

1215

N. Ohuchi, K.A. Aoki, Y. Arimoto, M.K. Kawai, T. Kawamoto, H. Koiso, Y. Kondo, M. Masuzawa, A. Morita, S. Nakamura, Y. Ohnishi, Y. Ohsawa, T. Oki, H. Sugimoto, K. Tsuchiya, R. Ueki, X. Wang, H. Yamaoka, Z.G. Zong
KEK, Ibaraki, Japan
M. Anerella, J. Escallier, A.K. Jain, A. Marone, B. Parker, P. Wanderer
BNL, Upton, Long Island, New York, USA
J. DiMarco, T.G. Gardner, J.M. Nogiec, M.A. Tartaglia, G. Velev
Fermilab, Batavia, Illinois, USA
T.-H. Kim
Mitsubishi Electric Corp, Advanced Technology R & D Center, Hyogo, Japan

The SuperKEKB collider aims at 40 times higher luminosity than that achieved at KEKB, based on the nano-beam scheme. The vertical beta function at the interaction point will be squeezed to 300μmeter. Final-focus superconducting magnet system which consists of eight main quadrupole magnets, 43 corrector windings, and compensation solenoids is a key component to achieve high luminosity. This invited talk presents the construction and commissioning of the final-focus magnet system.

Slides TUZGBE2 [4.235 MB]

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TUZGBE3

Towards Implementation of Laser Engineered Surface Structures for Electron Cloud Mitigation

electron, laser, vacuum, multipactoring

1220

M. Sitko, V. Baglin, S. Calatroni, P. Chiggiato, B. Di Girolamo, E. Garcia-Tabares Valdivieso, M. Taborelli
CERN, Geneva, Switzerland
A. Abdolvand, D. Bajek, S. Wackerow
University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
M. Colling, T.J. Jones, P.A. McIntosh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The LHC operation has proven that the electron cloud could be a significant limiting factor in machine performance, in particular for future High Luminosity LHC (HL-LHC) beams. Electron clouds, generated by electron multipacting in the beam pipes, leads to beam instabilities and beam-induced heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) is a novel surface treatment which changes the morphology of the internal surfaces of vacuum chambers. The surface modification results in a reduced secondary electron yield (SEY) and, consequently, in the eradication of the electron multipacting. Low SEY values of the treated surfaces and flexibility in choosing the laser parameters make LESS a promising treatment for future accelerators. LESS can be applied both in new and existing accelerators owing to the possibility of automated in-situ treatment. This approach has been developed and optimised for the LHC beam screens in which the electron cloud has to be mitigated before the HL-LHC upgrade. We will present the latest steps towards the implementation of LESS.

Slides TUZGBE3 [1.825 MB]

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TUZGBE5

A Combined Temperature and Magnetic Field Mapping System for SRF Cavities

cavity, 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]

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TUPMF007

Cryogenic Testing and Initial Performance of a Helical Superconducting Undulator at the APS

vacuum, undulator, cryogenics, radiation

1260

J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, M. Kasa, I. Kesgin, Y. Shiroyanagi
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science under Contract No. DE-AC02-06CH11357.
A helical superconducting undulator (HSCU) has been installed and is presently operational at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). We describe the final assembly and cryogenic test program which led to successful operation, representing the culmination of a two-year development effort. Details of the cryostat and cryogenic system design are presented along with as-installed performance data and a comparison with design expectations.

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TUPMF018

Simulation Studies of the Helical Superconducting Undulator Installed at APS

multipole, simulation, undulator, storage-ring

1290

A. Xiao, V. Sajaev, Y.P. Sun
ANL, Argonne, Illinois, USA

A multi-year project at APS has resulted in construction of a helical superconducting undulator (HSCU) for installation in the ring. Before installation, simulation studies were done to ensure that APS performance will not be compromised. This paper describes the method used for calculating the HSCU's perturbation effects and the simulation results for both calculated and measured field map.
Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

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TUPMF025

LEReC Photocathode DC Gun Beam Test Results

gun, cathode, laser, electron

1306

D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, A.V. Fedotov, D.M. Gassner, X. Gu, L.R. Hammons, P. Inacker, J.P. Jamilkowski, J. Kewisch, C.J. Liaw, C. Liu, K. Mernick, T.A. Miller, M.G. Minty, V. Ptitsyn, T. Rao, J. Sandberg, S. Seletskiy, P. Thieberger, J.E. Tuozzolo, E. Wang, Z. Zhao
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Low Energy RHIC Electron cooler (LEReC) project is presently under commissioning at Brookhaven National Laboratory (BNL). LEReC requires high average current up to 85mA and high-quality electron beam. A 400 kV DC gun equipped with a photocathode and laser system has been chosen to provide a source of high-quality electron beams. We started testing the DC gun during the RHIC run 2017. First electron beam from LEReC DC gun was delivered in April 2017 *. During the DC gun test critical elements of LEReC such as laser beam system, cathode exchange system, cathode QE lifetime, DC gun stability, beam instrumentation, the high-power beam dump system, machine protection system and controls have been tested. Average current of 10 mA for few hours of operation was reached in August 2017. In this paper we present experimental results and experience learned during the LEReC DC gun beam testing.
* D. Kayran et al., "First Results of Commissioning DC Photo-gun for RHIC Low Energy Electron Cooler (LEReC)", in Proc of ERL2017.

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TUPMF030

Operation and Performance of NSLS-II

emittance, feedback, MMI, photon

1312

G.M. Wang
BNL, Upton, Long Island, New York, USA

NSLS-II facility hosts 23 operating beamlines with 2 more under commissioning. The radiation sources varies, including damping wiggler, IVU, EPU, 3PW, and bending magnets. Over the past year, the storage ring performance continuously improved, including frequency feedback and photon local feedback. Machine reliability reached 96.9% for 4500 hrs operation with beam current upto 350 mA. Beam orbit short and long term stability has been significantly improved. Operation beam emittance were optimized with beamlines.

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TUPMF035

First Demonstration of the Transparent Fast-to-slow Corrector Current Shift in the NSLS-II Storage Ring

feedback, experiment, lattice, photon

1323

X. Yang, V.V. Smaluk, Y. Tian, L. Yu
BNL, Upton, Long Island, New York, USA

To realize the full benefits of the high brightness and ultra-small beam sizes of NSLS-II, it is essential that the photon beams are exceedingly stable (a level of 10% beam size). In the circumstances of implementing local bumps, changing ID gaps, and long-term drifting, the fast orbit feedback (FOFB) requires shifting the fast corrector strengths to the slow correctors to prevent the fast corrector saturation and to make the beam orbit stable in the sub-micron level. As the result, a reliable and precise technique of fast-to-slow corrector strength shift has been developed and tested at NSLS-II. This technique is based on the fast corrector response to the slow corrector change when the FOFB is on. In this article, the shift technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented. The maximum fast corrector current was reduced from greater than 0.45 A to less than 0.04 A with the orbit perturbation within ±1 μm. Especially when the step size of the shift was below 0.012 A, the amount of noise being added to the beam was none.

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TUPMF036

Top Off of NSLS-II with Inefficient Injector

booster, injection, linac, storage-ring

1327

R.P. Fliller, A.A. Derbenev, V.V. Smaluk, X. Yang
BNL, Upton, Long Island, New York, USA

Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
The NSLS-II is a 3 GeV storage with a full energy injector capable of top off injection. The injector consists of a 200 MeV linac injecting a 3 GeV booster. Recent operational events have caused us to investigate 100 MeV injection into the booster. As the booster was not designed for injection at this low energy, beam loss is observed with this low energy booster injection. This beam loss not only results of overall charge loss from the train, but a change in the overall charge distribution in the bunch train. In this paper we discuss the performance of injecting into the storage ring with the inefficient charge transfer through the injector. The changes to the top off method are discussed, as well as the achieved storage ring current stability and fill pattern.

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TUPMF037

Development of New Operational Mode for NSLS-II Injector: Low Energy 100MeV Linac-to-Booster Injection

booster, injection, klystron, linac

1330

X. Yang, A.A. Derbenev, R.P. Fliller, T.V. Shaftan, V.V. Smaluk
BNL, Upton, Long Island, New York, USA

The NSLS-II injector consists of a 200 MeV linac and a 3 GeV full-energy booster synchrotron. The linac contains five traveling-wave S-band accelerating structures driven by two high-power klystrons, with a third klystron as spare. In the event that the spare klystron is not available, the failure of one klystron will prohibit the linac from injecting into the booster as the energy is too low. Therefore, we wish to develop a new operational mode that the NSLS-II injector can operate with a single klystron providing 100 MeV beam from the linac. A decremented approach with intermediate energies 170 MeV, 150 MeV, etc., takes advantages of pre-calculated booster ramps and beam based online optimization. By lowering the booster injection energy in a small step and online optimizing at each step, we were able to achieve 100 MeV booster injection. 170 MeV operation mode of the NSLS-II injector has been implemented since May 31, 2017, with a similar overall performance compared to the standard 200 MeV operation but fewer klystron trips. 100 MeV single-klystron operation has been successfully demonstrated with 20-30% overall efficiency, which is limited by booster acceptance.

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TUPMF080

Progress on Multibunch FEL Performance at FLASH

cavity, 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.

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TUPMF090

Status of the Superconducting Soft X-Ray Free-Electron Laser FLASH at DESY

FEL, laser, undulator, electron

1481

M. Vogt, K. Honkavaara, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, R. Treusch
DESY, Hamburg, Germany

FLASH, the free-electron laser (FEL) user facility at DESY, has delivered high brilliance VUV and soft x-ray FEL radiation for photon experiments since summer 2005. In 2014 and 2015 a second beamline, FLASH2, has been commissioned in parallel to user operation at FLASH1. FLASH's superconducting linac can produce bunch trains of up to 800 bunches within a 0.8 ms RF flat top at a repetition rate of 10 Hz. In standard operation during 2017 FLASH supplied up to 500 bunches in two bunch trains with independent fill patterns and compression schemes. Since mid 2017 initial commissioning of a third experimental beamline, accommodating the FLASHForward plasma wakefield acceleration experiment, has started. We report on the highlights of the FLASH operation in 2017/2018.

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TUPMK012

Acceleration of Charged Particles by Own Field in a Non-Stationary One-Dimensional Stream

interface, ECR, electron, acceleration

1516

A.S. Chikhachev
Allrussian Electrotechnical Institute, Moskow, Russia

The behavior of a non-stationary stream of the charged particles interacting with own field is studied. For the description the integral of the movement received in works * ** - Meshchersky's integral is used. The additional integral of the movement - interfaced to Meshchersky's integral, necessary for completely self-agreed description of a stream of the particles interacting with own field is constructed. The system of the equations reducing a problem to the solution of system of the ordinary differential equations is removed. Private decisions for potential, density of particles and density of current are provided. Earlier the problem was studied in work ***.
* Mestschersky J. Astronomische Nachrichten, 1893, T.132, N3153, p. 9.
** Nestschersky ibid, 1902, T.159, N3807, p. 15.
*** Chikhachev A.S., Technical Phisics, 2014, vol 59, N 4, pp 487-493.

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TUPML014

CO2 CPA Laser Development for User Experiments in Advanced Accelerators and Radiation Sources

laser, experiment, plasma, optics

1556

M.N. Polyanskiy, M. Babzien, M.A. Palmer, I. Pogorelsky
BNL, Upton, Long Island, New York, USA

The ATF* is a National User Facility for advanced research in accelerator physics and technology. The ATF's terawatt CO2 laser is a unique scientific instrument allowing researchers to explorer new particle acceleration mechanisms and to study light/matter interaction at an order-of-magnitude longer photon wavelengths compared to the majority of other laser research facilities (λ≈10μm). Continuous development over more than two decades brought the ATF's CO2 laser to the limit of peak power achievable in a conventional gas laser MOPA configuration (in ATF's amplifier geometry this is ~0.5 TW in routine operation, and up to 2 TW in some experiments). To overcome this limit, we employ, for the first time in a gas laser, a chirped-pulse amplification (CPA) scheme. The goal of our current research and development effort is to demonstrate 3-5 TW peak power at the system output and to reliably deliver a large fraction of this power as a high-quality beam to a range of user experiments. Achieving this goal will lay the ground work for implementation of a >10 TW mid-IR laser system "BESTIA" that is currently being constructed as a part of the ATF-II project.
*Accelerator Test Facility at Brookhaven National Laboratory

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TUPML016

High-Intensity Magnetron H⁻ Ion Sources and Injector Development at BNL Linac

rfq, ion-source, injection, linac

1564

A. Zelenski, G. Atoian, T. Lehn, D. Raparia, J. Ritter
BNL, Upton, Long Island, New York, USA

The BNL magnetron-type H⁻ ion source and the injec-tor are being upgraded to higher duty-factor as a part of Linac intensity increase project [1]. The BNL magnetron source presently delivers 110 -120 mA H⁻ ion current with 650 us pulse duration and 7 Hz repetition rate. The pulse duration was increased to 1000 μs by modifications of the gas injector pulsed valve and the use of the new arc-discharge power supply (with the arc-current stabilization circuit) which improved current stability and reduced current noise. The Low Energy Beam Transport (LEBT) lines combine two beams. The first line is the polarized OPPIS (Optically Pumped Polarized H⁻ Ion Source) beam-line and the second is the high-intensity un-polarized beam-line from the magnetron source, which transports beam to the RFQ after the passage of 45 degree bending magnet. The second magnetron source was installed in the straight LEBT section in 2017, in which the polarized OPPIS beam was not planned. In this, optimal for H⁻ beam transport configuration, the beam intensity was increased to 80 mA after the RFQ. The experience of the two sources layout operation (one source in operation the second source in standby) might be useful for facilities with the high downtime cost (like high-energy collider LHC or multi-user facilities like SNS).

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TUPML053

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

cathode, cavity, SRF, 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.

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TUPML075

Development of Target/ion Source for Li-8 Beam at KOMAC*

target, ion-source, proton, vacuum

1718

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

Funding: This work has been supported through KOMAC operation fund of KAERI by MSIT and the NRF of Korea grant funded by the Korea government (MSIT) (No. NRF-2017M2A2A6A02071070).
A target/ion source (TIS) for Li-8 isotope beam has been developed at Korea Multi-purpose Accelerator Complex (KOMAC). The TIS was designed based on various numerical studies such as Monte Carlo simulation for Li-8 yield estimation, an ionization efficiency calculation of a surface ionization ion source and thermal analysis by a power balance model. Then, it was fabricated that a prototype of the TIS which consists of a beryllium oxide (BeO) target, a graphite target container, a tantalum target heater and a rhenium surface ion source. Also, the target heater and the surface ion source were heated to designed operation temperatures. In addition, it has been designed and constructed that an online test facility including Li-8 beam optics and diagnostics.

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WEXGBD2

Pulse-by-Pulse Multi-XFEL Beamline Operation with Ultra-Short Laser Pulses

electron, FEL, optics, undulator

1740

T. Hara, T. Inagaki, H. Maesaka, Y. Otake, H. Tanaka, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
K. Fukami
JASRI/SPring-8, Hyogo-ken, Japan
T. Hasegawa, O. Morimoto, S. Nakazawa, M. Yoshioka
SES, Hyogo-pref., Japan
H. Kawaguchi, Y. Kawaguchi
Nichicon (Kusatsu) Corporation, Shiga, Japan
C. Kondo
JASRI, Hyogo, Japan

The parallel operation of multiple beamlines is an important issue to expand the opportunity of user experiments for linac based FELs. At SACLA, the parallel operation of three beamlines, BL1~3, has been open to user experiments since September 2017. BL1 is a soft x-ray beamline driven by a dedicated accelerator, which is a former SCSS linac, and BL2 and 3 are XFEL beamlines, which share the electron beam from the SACLA main linac. In the parallel operation, a kicker magnet with 10 ppm stability (peak-to-peak) switches the two XFEL beamlines at 60 Hz from pulse to pulse. To ensure wide spectral tunability and optimize the laser performance, the energies and lengths of the electron bunches are independently adjusted for the two beamlines according to user experiments. Since the electron bunch of SACLA has typically 10~15 fs (FWHM) in length and its peak current exceeds 10 kA, the CSR effect at a dogleg beam transport to BL2 is quite significant. In order to suppress the CSR effects, an isochronous and achromatic lattice based on two DBA structures was introduced. In this talk, the multiple XFEL beamline operation and achieved laser performance are presented.

Slides WEXGBD2 [9.708 MB]

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WEXGBF1

Testing of the ESS MB-IOT Prototypes

klystron, linac, cavity, 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]

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WEYGBD1

12 GeV CEBAF Initial Operational Experience and Challenges

MMI, cryomodule, experiment, cavity

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]

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WEYGBD2

Status of the Radiation Damage on the European XFEL Undulator Systems

undulator, radiation, FEL, electron

1776

F. Wolff-Fabris, J. Pflüger
XFEL. EU, Schenefeld, Germany
F. Hellberg
Stockholm University, Stockholm, Sweden
F. Schmidt-Föhre
DESY, Hamburg, Germany

The European XFEL GmbH is a new X-ray FEL user facility and started lasing in 2017. Three gap movable SASE Undulator Systems are designed to produce FELs with tunable wavelengths from 0.05 to 5.2nm [*,**]. A total of 91 5-m long undulator segments based on hybrid NdFeB permanent magnet technology were tuned respecting tight specifications. Radiation damage due to machine operation affects the magnetic properties of the segments and the quality of the SASE process. An array of dosimeters based on Radfets [***] and Gafchromic films monitors the absorbed doses in every undulator segment and each SASE system is equipped with a 12mm gap diagnostic undulator (DU) which is magnetically re-measured during machine maintenance weeks. Doses up to 4 kGy have been observed and magnetic field degradation higher than 3% is measured. These results permit to estimate the effects of radiation damage and life expectancy of the Undulator Systems based on the precise K-parameter determination for beam operation. We will present the results of magnetic re-measurements on the Undulator Systems, the details of the effects of radiation damage and future plans to maximize the beam quality and operation.
* M. Altarelli et al., Tech. Design Rep. DESY 2006-097, July 2007.
** E. Schneidmiller et al., Eur. XFEL Tech. Rep. TR-2011-006, Sep. 2011.
*** F. Schmidt-Föhre et al., IPAC-2018 contribution.

Slides WEYGBD2 [3.670 MB]

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WEYGBE4

Low-Impedance Collimators for HL-LHC

impedance, octupole, collimation, luminosity

1794

S. A. Antipov, N. Biancacci, R. Bruce, A. Mereghetti, D. Mirarchi, E. Métral, S. Redaelli, B. Salvant
CERN, Geneva, Switzerland
D. Amorim
Université Grenoble Alpes, Grenoble, France

The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) will double its beam intensity for the needs of High Energy Physics frontier. This increase requires a reduction of the machine's impedance to ensure the coherent stability of the beams until they are put in collision. A major part of the impedance is the resistive wall contribution of the collimators. To reduce this contribution several coating options have been proposed. We have studied numerically the effect of the novel coatings on the beam stability. The results show that a decrease of up to 30% of the machine impedance and a reduction of up to 120 A in the stabilizing octupole current threshold can be achieved by coating the secondary collimators with Molybdenum. Half of that improvement can be obtained by coating the jaws of a subset of four collimators identified as the highest contributors to machine impedance. The installation of this subset of low-impedance collimators is planned for the Long Shutdown 2 in 2019-2020.

Slides WEYGBE4 [5.719 MB]

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WEPAF005

A Fast Beam Interlock System for the Advanced Photon Source Particle Accumulator Ring

radiation, photon, shielding, detector

1815

J.C. Dooling, M. Borland, K.C. Harkay, R.T. Keane, B.J. Micklich, C. Yao
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Of- fice of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A fast beam interlock system for the Advanced Photon Source (APS) Particle Accumulator Ring (PAR) based on the detection of Cerenkov light is proposed for high-charge operations associated with the APS Upgrade (APS-U). Light is generated from lost electrons passing through high-purity, fused-silica fiber optic cable. The cable acts as both radiator and light pipe to a Pb-shielded photomultiplier tube. Results from a prototype installation along the PAR south wall have shown excellent sensitivity, linearity, and reproducibility after 10,000 hours of operation to date with little change in the optical transmission of the fiber. High sensitivity allows more accurate measurement of low-level loss than possible with current monitors. The radiator and detector provide a much faster response than the installed gamma or neutron detectors. A faster, more accurate response to electron loss will be important as we run with higher charge and consider operating at increased energy for APS-U. Initial calibration measurements of the prototype system with radiation monitors for various loss scenarios are discussed. Comparison of the scenarios with simulations are presented.

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WEPAF010

Fast Glitch Detection of Coupled Bunch Instabilities and Orbit Motions

feedback, vacuum, storage-ring, injection

1829

W.X. Cheng, B. Bacha, K. Ha, Y. Li
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE contract No: DE-SC0012704
During high current operation at NSLS-II storage ring, vertical beam size spikes have been noticed. The spikes are believed due to ion instability associates with vacuum activities localized in the ring. A new tool has been developed using gated BPM turn-by-turn (TBT) data to detect beam centroid glitches. When one turn orbit deviates outside the predefined window, a global event will be generated. This allows synchronized data acquisition of TBT beam positions around the ring. Bunch by bunch data is acquired at the same time to analyze the possible coupled bunch instabilities (CBI). Besides CBI mainly due to ion bursts, fast orbit glitches have been captured with the new tool. Sources of the glitches can be identified.

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WEPAF011

Developments of Bunch by Bunch Feedback System at NSLS-II Storage Ring

feedback, emittance, vacuum, storage-ring

1833

W.X. Cheng, B. Bacha, Y. Li
BNL, Upton, Long Island, New York, USA
D. Teytelman
Dimtel, San Jose, USA

Funding: Work supported by DOE contract No: DE-SC0012704
Transverse bunch-by-bunch (BxB) feedback system has been constructed and in operation since the very beginning of NSLS-II storage ring commissioning. As the total beam current continues increasing in the past years, the system has been operating stable and reliable. Advanced BxB diagnostic functions have been developed using the system. Continuous tune measurement is realized with a diagnostic single bunch. Coupled bunch instability growth rate is able to be measured with the transient excitation. The BxB feedback system is also capable to excite a small fraction of total bunches for lattice measurement during high current operations. We present the most recent developments and operation experience on the BxB feedback system at NSLS-II.

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WEPAF017

Correction of ID-Induced Transverse Linear Coupling at NSLS-II

coupling, emittance, quadrupole, resonance

1856

Y. Hidaka, Y. Li, T.V. Shaftan, T. Tanabe, Y. Tian, G.M. Wang
BNL, Upton, Long Island, New York, USA

Funding: The study is supported by U.S. DOE under Contract No. DE-AC02-98CH10886.
Sizeable lifetime jumps have been observed sporadically since March 2016 at NSLS-II. These jumps were found to coincide with insertion device (ID) gap motions. Particularly, one of the in-vacuum undulators (IVUs) at Cell 17 was discovered to have large localized skew quadrupole component variation with gap. To allow the machine to operate stably in the low-emittance mode, a global coupling feedforward system has been recently implemented and successfully deployed. After installation of a new additional skew quadrupole, coupling compensation of this ID is now performed by a local coupling feedforward system. Furthermore, the maximum gap limit of all the existing IVUs has been decreased from 40 mm to 25 mm to limit the skew component variation during user operation.

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WEPAF022

Application of Machine Learning to Minimize Long Term Drifts in the NSLS-II Linac

klystron, linac, network, booster

1867

R.P. Fliller, C. Gardner, P. Marino, R.S. Rainer, M. Santana, G.J. Weiner, X. Yang, E. Zeitler
BNL, Upton, Long Island, New York, USA

Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
Machine Learning has proven itself as a useful technique in a variety of applications from image recognition to playing Go. Artificial Neural Networks have certain advantages when used as a feedforward system, such as the predicted correction relies on a model built from data. This allows for the Artificial Neural Network to compensate for effects that are difficult to model such as low level RF adjustments to compensate for long term drifts. The NSLS-II linac suffers from long terms drifts from a number of sources including thermal drifts and klystron gain variations. These drifts have an effect on the injection efficiency into the booster, and if left unchecked, portions of the bunch train may not be injected into the booster, and the storage ring bunch pattern will ultimately suffer. In this paper, we discuss the application of Artificial Neural Networks to compensate for long term drifts in the NSLS-II linear accelerator. The Artificial Neural Network is implemented in python allowing for rapid development of the network. We discuss the design and training of the network, along with results of using the network in operation.

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WEPAF030

HEPS High-Level Software Architecture Plan

database, software, controls, EPICS

1884

C.P. Chu, Y.S. Qiao, C.H. Wang
IHEP, Beijing, People's Republic of China
H.H. Lv
SINAP, Shanghai, People's Republic of China

Funding: Work supported by the Chinese Academy of Science and the HEPS-TF Project.
The High Energy Photon Source (HEPS) is a planned ultra-low emittance synchrotron radiation based light source which requires high precession control systems for both accelerator and beamlines. Such kind of accelerators will require extremely sophisticated high-level control software for both accelerator and beamline operation to achieve not only the demanded precision but also high reliability. This paper outlines the high-level application software architecture design including relational data-bases, software platforms, and advanced controls with machine learning (ML) techniques. Early plan for beam-line control is also reported. For better quality control and easy maintenance, the high-level applications will be built upon matured software platforms. Also, the HEPS High-Level Software team will collaborate with EPICS community for improving the software platforms.

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WEPAF043

Commissioning and Long-Term Results of a Fully-Automated Pulse-Based Optical Timing Distribution System at Dalian Coherent Light Source

timing, laser, electron, detector

1909

H.P.H. Cheng, A. Berlin, E. Cano, A. Dai, J. Derksen, D. Forouher, W. Nasimzada, M. Neuhaus, P. Schiepel, E. Seibel, K. Shafak
Cycle GmbH, Hamburg, Germany
Z. Chen, H.L. Ding, Z.G. He, Y.H. Tian, G.R. Wu
DICP, Dalian, People's Republic of China
F.X. Kärtner
Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
B. Liu, X.Q. Liu
SINAP, Shanghai, People's Republic of China

New generation light sources such as X-ray free-electron lasers* and attoscience centers** require high demand for timing synchronization, on the order of few femtoseconds or below, to generate ultrashort X-ray pulses that enables attosecond temporal and subatomic spatial resolution. The challenge in achieving this scientific dream lies in part in a reliable, high-precision timing distribution system that can synchronize various optical and microwave sources across multi-km distances with good long-term stability. It was shown that the pulsed-optical timing distribution system can deliver sub-fs long-term timing precision between remotely synchronized lasers and microwave sources in laboratory environment.*** We present the latest results from the commissioning of China's first multi-link pulse-based optical timing distribution system (TDS) installed at Dalian Coherent Light Source. Long term operating results of the fully-automated polarization-maintaining TDS, as well as lessons learned and recommendations for future improvements, are presented, including performance of the timing-stabilized PM fiber links, microwave end-stations and ultrafast laser synchronization end-stations.
*http://www.xfel.eu/news/2017/european_xfel_generates_its_first_laser_light
**G. Mourou and T. Tajima, Science, 331, pp. 41-42, 2011.
***M. Xin et al., Light Sci. Appl., 6, e16187, 2017.

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WEPAF044

Automatic Tuning of PETRA, its Injector Complex, and Prospects of Autonomous Operation of PETRA IV

controls, optics, software, synchrotron

1912

I.V. Agapov, H. Ehrlichmann, J. Keil, G.K. Sahoo, R. Wanzenberg
DESY, Hamburg, Germany
Y.-C. Chae
ANL, Argonne, Illinois, USA

We present the progress in tuning automation of the PETRA injection complex. The OCELOT optimizer has been ported to the PETRA control system and proof-of-principle tests of transmission efficiency optimization done. We further argue that the next steps in tuning and automation are impossible without rethinking the architecture of the high level contol system. A possible approach to the new system is then sketched.

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WEPAF048

High Resolution and Low Charge Button and Strip-Line Beam Position Monitor Electronics Upgrade at Flash

electron, electronics, FEL, laser

1923

B. Lorbeer, N. Baboi, H.T. Duhme, Re. Neumann
DESY, Hamburg, Germany

Historically the FLASH (Free Electron Laser in Hamburg) facility at DESY (Deutsches Elektronen-Synchrotron) in Germany has foreseen operation in a charge range from 1nC-3nC for which a VME based BPM(Beam Position Monitor) system has been in operation since 2005. For a couple of years the standard machine operation has been settled at a few hundreds of pC with the tendency for smaller charges down to 100pC and smaller. The availability and resolution performance of the BPM system at charges below 300pC in many locations along the machine was unsatisfactory. In the last couple of years a new BPM electronic system based on the utca standard has been developed to overcome these limitations. A substantially improved version of the analog frontend and digital electronics has been developed in 2016 and tested successfully. During shutdown works at FLASH in summer 2017 all old button and strip-line BPM electronics has been replaced with the new type of electronics. This paper summarizes the features and performance of the new BPM system, compares the beam jitter free resolution of old and new BPM system and highlights its high single shot resolution of better than 10um at a charge of 15pC.

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WEPAF051

LLRF Operation and Performance at the European XFEL

LLRF, electron, FEL, MMI

1934

M. Omet, V. Ayvazyan, J. Branlard, L. Butkowski, M. Hierholzer, M. Killenberg, D. Kostin, L. Lilje, S. Pfeiffer, H. Schlarb, Ch. Schmidt, V. Vogel, N. Walker
DESY, Hamburg, Germany

The European X-ray Free-Electron Laser (XFEL) at Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany is a user facility providing ultrashort hard and soft X-ray flashes with a high brilliance. All LLRF stations of the injector, covering the normal conducting RF gun, A1 (8 1.3 GHz superconducting cavities (SCs)) and AH1 (8 3.9 GHz SCs), were successfully commissioned by the end of 2015. The commissioning of LLRF stations A2 to A23 (32 1.3 GHz SCs each) in the XFEL accelerator tunnel (XTL) was concluded in June 2017. SASE light was produced in SASE undulator section SA1 and delivered to the first users in September 2017, marking the beginning of regular user operation. The current state of the LLRF systems, the experience gained during operation and the performance achieved in terms of stability and energy reach are presented.

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WEPAF052

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

cavity, feedback, 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.

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WEPAF064

Dependable Implementation of the Beam Interlock Mechanism in CERN Power Converter Controllers

controls, software, experiment, interface

1975

M. Di Cosmo, Q. King, R. Murillo-Garcia, D. Nisbet, B. Todd
CERN, Geneva, Switzerland

At CERN a Beam Interlock System (BIS) protects accelerators from accidental and uncontrolled release of beam energy, avoiding machine downtime. Throughout the accelerator complex numerous critical subsystems, including power converters, interact with the BIS indicating their readiness for operation with beam. Power converters play a vital role in establishing operational conditions, and an unmitigated power converter malfunction could lead to damage to the machine. For example a bending magnet converter set at an incorrect current would result in an incorrect field strength, and beam passing through this may impact and damage the machine. A fast and dependable Beam Interlock Mechanism is required between power converters and BIS, verifying that voltage and current levels are within tolerances. This paper describes the design and realisation of the Beam Interlock Mechanism, based on CERN's Function Generator Controller (FGC), the central processing unit power converter control. Particular emphasis is placed on the system architecture required to assure the integrity of the power converter parameters, and the protection of the CERN accelerator complex.

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WEPAF075

Availability Allocation to Particle Accelerators Subsystems by Complexity Criteria

factory, collider, linear-collider, target

2009

O. Rey Orozko, A. Apollonio, M. Jonker, J.A. Uythoven
CERN, Geneva, Switzerland

In the early design stages of an accelerator, an effective allocation method is needed to translate an overall accelerator availability goal into availability requirements for its subsystems. During the allocation process, many factors are considered to obtain so-called ‘complexity weights', which are at the basis of the system availability allocation. Some of these factors can be measured quantitatively while other have to be assessed qualitatively. Based on our analysis of factors affecting availability, we list six criteria for complexity resulting in an availability allocation of accelerator subsystems. System experts determine the scales of factors and relationships between subsystems. In this paper, we consider four availability apportionment techniques to allocate complexity weights to subsystems. Finally, we apply this method to the Compact Linear Collider (CLIC) and we propose another application of the complexity weights to the Large Hadron Collider (LHC).

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WEPAF076

Availability Studies Comparing Drive Beam and Klystron Options for the Compact Linear Collider

klystron, simulation, linac, software

2013

O. Rey Orozko, S. Döbert, M. Jonker
CERN, Geneva, Switzerland

The initial proposal for the Compact Linear Collider (CLIC) is based on a two beam-scheme to accelerate the main colliding beams. For low collision energies, the main beam could also be accelerated by powering the accelerating structures with klystrons instead of the two-beam scheme. This paper studies the feasibility of this new alternative in terms of machine availability. An implemented bottom-up availability model considers the components failure modes to estimate the overall availability of the system. The model is defined within a Common Input Format scheme and the AvailSim3 software package is used for availability simulations. This paper gives an overview of the systems affecting the beam powering availability and makes recommendations for availability improvements.

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WEPAF077

Performance Evaluation of Linac4 During the Reliability Run

linac, MMI, proton, controls

2016

O. Rey Orozko, A. Apollonio, S.S. Erhard, G. Guidoboni, B. Mikulec, J.A. Uythoven
CERN, Geneva, Switzerland

Linac4 will replace Linac2 as the first element in the CERN proton injector chain from 2020 onwards, following the second LHC long shutdown (LS2). With more than three times higher energy and number of compo-nents than Linac2, beam availability is one of the main challenges of Linac4. Intended as a smooth transition from commissioning to operation, a Linac4 Reliability Run was started in July 2017 and is foreseen to last until mid-May 2018. The goal is to achieve the target availability of 95 %. This implies consolidated routine operation and identification of recurring problems. This paper introduces the schedule and operational aspects of the Linac4 Reliability Run, including the developed tools and methods for availability tracking. The paper also summarizes the lessons learned during the first period of the Linac4 Reliability Run with respect to fault tracking and provides an in-depth analysis of the failure modes and observed availability.

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WEPAF079

A Smart Framework for the Availability and Reliability Assessment and Management of Accelerators Technical Facilities

framework, GUI, controls, experiment

2024

L. Serio, A. Castellano, U. Gentile
CERN, Geneva, Switzerland
F. Antonello, P. Baraldi, E. Zio
Politecnico di Milano, Milan, Italy

CERN operates and maintains a large and complex technical infrastructure serving the accelerator complex and experiments detectors. A performance assessment and enhancement framework based on data mining, artificial intelligence and machine-learning algorithms is under development with the objective of structuring, collecting and analyzing systems and equipment operation and failure data, to guide the identification and implementation of adequate corrective, preventive and consolidation interventions. The framework is designed to collect and structure the data, identify and analyze the associated driving events. It develops dynamically functional dependencies and logic trees, descriptive and predictive models to support operation and maintenance activities to improve the reliability and availability of the installations. To validate the performance of the framework and quality of the algorithms several case studies are being carried out. We report on the design, implementation and on the preliminary results inferred on historical and live stream data from CERN's technical infrastructure. Proposal for the full deployment and expected long-term capabilities will also be discussed.

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WEPAF082

A Systematic Analysis of the Prompt Dose Distribution at the Large Hadron Collider

radiation, luminosity, experiment, proton

2036

O. Stein, K. Bilko, M. Brugger, S. Danzeca, D. Di Francesca, R. Garcia Alia, Y. Kadi, G. Li Vecchi, C. Martinella
CERN, Geneva, Switzerland

During the operation of the Large Hadron Collider (LHC) the continuous particle losses create a mixed particle radiation field in the LHC tunnel and the adjacent caverns. Exposed electronics and accelerator components show dose dependent accelerated aging effects. In order to achieve an optimal lifetime associated to radiation damage, the position of the equipment is chosen in dependency of the amplitude of the radiation fields. Based on the continuous analysis of the data from more than 3900 ionisation chamber beam loss monitors the evolution of the radiation levels is monitored during the accelerator operation. Normalising the radiation fields with either the integrated luminosity or the integrated intensities allows extrapolating the radiation levels of future accelerator operation. In this paper, the general radiation levels in the arcs and the insertion regions at the LHC and their evolution will be presented. The changes in the prompt dose distribution along the LHC between the operation in 2016 and 2017 will be discussed. The impact of different accelerator settings on the local dose distribution will be addressed as well.

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WEPAF083

Distributed Optical Fiber Radiation Sensing at CERN

radiation, synchrotron, distributed, extraction

2039

G. Li Vecchi, M. Brugger, S. Danzeca, D. Di Francesca, R. Ferraro, Y. Kadi, O. Stein
CERN, Geneva, Switzerland
S. Girard
Univ-Lyon Laboratoire H. Curien, UMR CNRS 5516, Saint Etienne, France

The CERN's accelerator tunnels are associated with very complex mixed field radiation environments. Radiation degrades electronic components and directly affects their lifetimes causing failures that contribute to the machine downtime periods. In our contribution, we will report on the development and first employment of a Distributed Optical Fiber Radiation Sensor (DOFRS) at CERN. The most interesting feature of DOFRS technology is to provide an online and spatially distributed map of the dose levels in large machines with spatial resolution of the order of one meter. This fiber based dose sensor will provide valuable information in addition to the currently installed active and passive dosimeters. After demonstrating the working principle of DOFRS*, the first operational prototype was installed in the Proton Synchrotron Booster during last 2016/17 end-of-the-year technical stop. The DOFRS has been acquiring data successfully since the beginning of 2017 operations. The performances that were achieved by the first prototype will be discussed in the final contribution. The DOFRS measurements will also be bench-marked to the results provided by other punctual dosimeters.
*I. Toccafondo et al., 'Distributed Optical Fiber Radiation Sensing in a Mixed-Field Radiation Environment at CERN,' J. Lightw. Technol. 35, 3303, 3310, 2017.

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WEPAG004

Automating Orbit Correction in the Main Injector 8 GeV Line

controls, dipole, booster, data-acquisition

2070

K.J. Hazelwood, I. Kourbanis, G.E. Krafczyk, M.-J. Yang
Fermilab, Batavia, Illinois, USA

The Main Injector 8 GeV line (MI8 line) transports beam from Fermilab's Booster accelerator to either the Booster Neutrino experiments (BNB), the Recycler or the Main Injector. Often the orbit of the beam through the MI8 line differs depending on the beam destination. The beam is collimated in the MI8 line, so increasing intensities and repetition rates make controlling orbits through the collimators a necessity. The current method of regulating the MI8 line orbit with DC corrector settings is insufficient. A system named MITUNE is being developed to sample and categorize all beams through the MI8 line and automatically calculate and apply proper dipole corrector ramps to maintain desired orbits for pulses to any destination.

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WEPAK009

Applications of the Interferometric Beam Size Monitor at BESSY II

storage-ring, diagnostics, electron, photon

2103

M. Koopmans, P. Goslawski, J.G. Hwang, A. Jankowiak, M. Ries, A. Schälicke, G. Schiwietz
HZB, Berlin, Germany

For the upgrade project of the BESSY~II storage ring to BESSY~VSR * an interferometric beam size monitor was designed and set up. Since this system uses visible light it can be upgraded efficiently to provide bunch resolved measurements. These are required for machine commissioning, development and to ensure long term quality and stability of user operation of BESSY~VSR. Various applications of the system are outlined and measurements are presented.
* A. Jankowiak et al., eds., BESSY VSR Technical Design Study, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Germany, June 2015. DOI: 10.5442/R0001

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WEPAK015

Beam Gate Control System for SuperKEKB

controls, injection, hardware, software

2124

H. Kaji, Y. Ohnishi, S. Sasaki, M. Satoh, H. Sugimura
KEK, Ibaraki, Japan
Y. Iitsuka
EJIT, Hitachi, Ibaraki, Japan
T. Kudou
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

The electron beam pulses of injector linac for the SuperKEKB collider are enabled and disabled by Beam Gate control system. This system controls the delivery of triggers to the electron guns at the injector. Also, the septum and kicker magnets for injection point of main ring are controlled with this Beam Gate to avoid unnecessary operation and to prolong their lifetime. The Beam Gate synchronizes the enabling and disabling operations of these hardware even though they are about 1km distant. Besides, from the phase-2 operation, the kicker and septum magnets for newly constructed damping ring becomes controlled apparatus of this system. We develop the new Beam Gate control system with the Event Timing System network*. The new system improves the unsatisfied performance of Beam Gate in the phase-1 operation and realizes the complicated control for phase-2. The advantages of new system are: the control signal is delivered via Event nettork, so that we do not need to cable new network. The enabling and disabling operations for distant hardware are surely synchronized by the Event Timing System.
* H. Kaji et al., "Construction and Commissioning Event Timing System at SuperKEKB", Proceedings of IPAC14, Dresden, Germany (2014).

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WEPAL002

Improvement of Personnel and Machine Protection System in Superkekb Injector Linac

linac, PLC, controls, gun

2140

I. Satake, H. Honma, A. Shirakawa, N. Toge
KEK, Ibaraki, Japan

Since summer of 2010, the radiation control area for the KEK electron positron injector linac had been split at the around 3 GeV point by a concrete wall into upstream and downstream parts with independent beam sources. This was so as to allow operation of the downstream part for beam injection into photon factory rings while construction and development of new electron guns proceed in the upstream part. In summer of 2017, this arrangement was revised and the entire injector linac was reconsolidated into a single radiation control area. This was in conjunction with the introduction of the 1.1 GeV positron damping ring for Phase-II operation of SuperKEKB and successful development of new electron RF guns in the far upstream part of the linac. Along with this reconsolidation, the personnel and machine protection system was modified and improved. Interlock signal lines for the damping ring and RF guns were added. The operation panel of the main console was modified accordingly. In addition, the screen displays of the interlock status were updated. In this paper we report on the renewed system of KEK injector linac in detail.

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WEPAL011

iPipe: An Innovative Fiber Optic Monitoring System for Beam Induced Heating on Accelerator Pipes

monitoring, experiment, radiation, detector

2166

F. Fienga, S. Buontempo, M.R. Masullo
INFN-Napoli, Napoli, Italy
A. Ball, N. Beni, B. Salvant, W. Zeuner
CERN, Geneva, Switzerland
G. Breglio, A. Irace
University of Napoli Federico II, Napoli, Italy
Z. Szillasi
ATOMKI, Debrecen, Hungary
V.G. Vaccaro
Naples University Federico II and INFN, Napoli, Italy

The iPipe project consists in the instrumentation, with Fiber Bragg Grating sensors (FBGs), of the beam pipe of the CMS experiment, which is part of the LHC. Being spectrally encoded, the FBGs are not sensitive to electromagnetic interference and broadband-radiation-induced losses. These characteristics allow to realize long distance punctual sensing systems, capable to operate in harsh environments like the underground experimental and accelerator facilities at CERN. The iPipe secures the measurement of any deformation induced on the central beam pipe by any motion in the CMS detector due to element displacement or to magnetic field induced deformations. Moreover, the iPipe FBG temperature sensors represent a unique solution to monitor the beam pipe thermal behavior during the various operational and maintenance phases. This paper reports the use of the iPipe to measure the beam induced heating on the CMS vacuum chamber throughout 2016 and 2017. A first comparison between the measurements and the heat load predicted from beam induced RF heating due to the coupling impedance of the CMS pipe is also reported.

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WEPAL015

Improvement of Motor Control System in J-PARC Linac and RCS

controls, hardware, radiation, PLC

2180

H. Takahashi, A. Miura, Y. Sawabe, M. Yoshimoto
JAEA/J-PARC, Tokai-mura, Japan
M. Kawase, T. Suzuki
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

In J-PARC, at the Linac wire scanner, the RCS collimator, and etc., a motor control system by VME is constructed as a drive system of them. Since the malfunction of operation occurred in the control system of the RCS collimator drive system in 2016, we decided to improve the motor control system. As a cause of malfunction, it is considered that aging of control equipment is one of them as J-PARC has been operated for more than 10 years. However, the defect did not occur in the reproduction test. Therefore, it can be considered that a malfunction occurred in the VME control system due to abnormality of the semiconductor element due to radiation ray. Then, in the improved motor control system, PLC with FA* specification with high reliability was adopted as the control device. Also, in case of unexpected event that a malfunction occurred in the PLC, the emergency stop mechanism was developed to stop the drive system by the signal of the limit switch, and a system incorporating it was constructed. In this paper, we show the inference of cause of the malfunction and details the improved motor control system with high safety.
* Factory Automation

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WEPAL023

Pulsed Operation at MAMI with High Beam Loading

experiment, beam-losses, klystron, beam-loading

2206

M. Dehn, K. Aulenbacher, F. Fichtner, P. Jennewein, W. Klag, H.-J. Kreidel, J.R. Röthgen
IKP, Mainz, Germany

Funding: Work supported by DFG (CRC 1044) and the German federal state of Rhineland-Palatinate
The Mainz Microtron Accelerator (MAMI) is a microtron cascade which is normally operated CW for particle physics experiments. For certain investigations it is necessary to use a pulsed beam (macro pulses, several milliseconds). Up to now this pulsed mode can only be applied if the beam loading for the accelerating RF structures is negligible. To achieve higher pulse intensities the accelerator RF infrastructure needs to be equipped with feed-forward techniques to compensate for the expected beam loading. To monitor beam losses the machine protection system at MAMI needs to be extended to be able to localize fast occurrences of beam losses. This paper will present the possibilities being investigated to allow pulsed operation of MAMI within the near future.

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WEPAL030

Deep Learning Based Predictive Control for RFT-30 Cyclotron

controls, cyclotron, network, simulation

2230

Y.B. Kong, M.G. Hur, E.J. Lee, J.H. Park, H.S. Song, S.D. Yang
KAERI, Jeongeup-si, Republic of Korea

Successful construction of the control system is an important problem in the accelerator. The RFT-30 cyclotron is 30 MeV cyclotron for radioisotope production and fundamental researches. To operate the RFT-30 cyclotron for beam irradiation, the human operators should carefully manipulate the control parameters. If the control does not function properly, it becomes difficult to handle the cyclotron and cannot perform the accurate operations for the control. In this work, we propose a deep learning based model predictive control approach for the RFT-30 cyclotron. The proposed approach is composed of two steps: system identification and a control design. In the system identification procedure, the proposed approach constructs the predictive model of the accelerator using the deep learning approach. In the control design stage, the controller finds the optimal control inputs by solving the optimization problem. To analyze the performance of the proposed approach, we applied the approach into the RFT-30 cyclotron.

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WEPAL051

Mirascope Residual-Gas Luminescent Beam Profile Monitors

electron, controls, diagnostics, proton

2291

V.G. Dudnikov, R.J. Abrams, M.A. Cummings
Muons, Inc, Illinois, USA

Muons, Inc. proposes to develop a Residual-Gas Beam Profile Monitor for Transfer Lines with pulse-to-pulse precision of better than 0.1 mm in position and size that will operate over a wide range of proton beam intensities including those needed for multi-MW beams of future facilities. Traditional solid-based beam intercepting instrumentation produces unallowable levels of radiation at high powers. Our alternative approach is to use a low mass residual-gas profile monitor, where ionization electrons are collected along extended magnetic field lines and the gas composi-tion and pressure in the beam pipe are locally controlled to minimize unwanted radiation and to improve resolu-tion. Beam Induced Fluorescence profile monitor with micrascope light collection is proposed.

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WEPAL054

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

LLRF, controls, cavity, 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.

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WEPAL059

Observation and Suppression of Beam Orbit Drift Due to Path Length Changes and Thermal Effect in TPS

site, feedback, controls, electron

2313

P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.-C. Kuo
NSRRC, Hsinchu, Taiwan

Tidal effect, ambient temperature fluctuation and other effects of the TPS site can cause the path length changes of the electron beam in the TPS storage ring. Off-energy orbit drifts from the path length change, if not varying the RF frequency, cannot be properly corrected by the horizontal correctors and this causes the fast orbit feedback system over its normal working range. RF frequency adjustment loop is therefore applied to compensate for the circumference change based on the accumulating corrector strengths of the fast orbit feedback system. Implementation and operational experiences will be discussed in the report.

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WEPAL062

Bunch Length Measurements with a Streak Camera in Low Alpha Lattice Operation at the TPS

synchrotron, lattice, photon, emittance

2316

C.H. Chen, J.Y. Chen, M.-S. Chiu, P.J. Chou, K.T. Hsu, K.H. Hu, C.-C. Kuo, C.C. Liang, C.Y. Liao, Y.-C. Liu, G.-H. Luo, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

We developed and tested lattice with lower momentum compaction factor (low alpha) in TPS (Taiwan Photon Source) recently. Operating low alpha lattice can provide picosecond bunch length for time-resolved research and coherent IR/THz synchrotron light. The bunch length around 2.5 picosecond rms was measured by a streak camera* in low alpha mode while operating in the routine users mode** it was around 10 picosecond. This paper presents the related processes and measurements.
* L.Y. Liao et al., "Preliminary beam test of synchrotron radiation monitoring system at Taiwan Photon Source", IPAC'15.
** C.C. Kuo et al., "Commissioning of Taiwan Photon Source", IPAC'15.

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WEPAL067

Number of Turn Measurements on the HIPA Cyclotrons at PSI

cyclotron, pick-up, proton, LabView

2334

P.-A. Duperrex, A. Facchetti
PSI, Villigen PSI, Switzerland

The number of turns is an important parameter for the tuning of a cyclotron; it is even more important for high intensity machines such as the 1.4 MW High Intensity Proton Accelerator (HIPA) facility. Up to recently, the number of turns had to be measured using radial probes, which cannot be performed during user operation but only during beam development shifts. For user shifts, the estimate of the number of turns was based on the acceleration voltage measurements, with the inherent limited precision of RF measurements. A new scheme based on the time of flight (ToF) measurements has been deployed on the two cyclotrons of HIPA. It is based on the cross-correlation of fast sampled data from pickups located at the entrance and at the exit of the cyclotrons. For the first cyclotron, called Injector 2 (accelerating the beam from 870 keV to 72MeV), the beam had to be externally modulated whereas, for the Ring Cyclotron (72 MeV to 590 MeV), no external modulation was necessary. This paper will present the details of both implementations, their limitations and the quality of the results that can be obtained with the ToF techniques.

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WEPAL068

Improving Machine and Target Protection in the SINQ Beam Line at PSI-HIPA

target, proton, quadrupole, diagnostics

2337

D. Reggiani, P.-A. Duperrex, R. Dölling, D.C. Kiselev, J. Welte, M. Wohlmuther
PSI, Villigen PSI, Switzerland

With a nominal beam power of nearly 1.4 MW, the PSI High Intensity Proton Accelerator (HIPA) facility is currently at the forefront of the high intensity frontier of particle accelerators. A key issue of this facility is to ensure safe operation of the SINQ spallation source. In particular, too large beam current density and/or inaccurate beam steering can seriously compromise the integrity of the spallation target. Recently, a campaign has been launched in order to improve the fast detection of improper beam delivery and therefore the reliability of the system. New beam diagnostics elements such as an absolute intensity monitor, a beam ellipticity monitor and additional loss monitors have been installed during the 2017 shutdown. In 2018 a new SINQ target will be installed featuring a system of thermocouples which will keep track of the beam position. Moreover, an additional monitor is currently under study which should reliably detect small beam fractions accidentally bypassing the muon production target TE and which are intrinsically dangerous for the SINQ spallation target. This contribution reviews the all efforts to increase the efficiency of the SINQ protection system.

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WEPMF002

Operational Experience with IOTs at Alba Synchrotron

cavity, cathode, electron, 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.

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WEPMF005

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

cavity, controls, 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.

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WEPMF008

Preliminary Designs and Test Results of Bipolar Power Supplies for APS Upgrade Storage Ring

power-supply, hardware, controls, storage-ring

2381

J. Wang, I.A. Abid, R.T. Keane, G.S. Sprau
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.
The upgrade (APS-U) of the APS storage ring requires more than 1200 bipolar power supplies. Based on the performance requirement, the power supplies can be divided into two categories: fast bipolar power supplies for fast correctors and slow bipolar power supplies for trim coils and slow correctors. The common requirement of the power supplies is a bipolar output current up to ±15 A. The main difference is that the fast corrector power supplies require a small-signal bandwidth of 10 kHz. A prototype DC/DC power converter utilizing a MOSFET H-bridge circuit with a 500 kHz PWM was successfully developed through the R&D program, achieving the required bandwidth with less than 3-dB attenuation for a signal 0.5% of ±15 A. After the successful R&D program, the preliminary designs were performed to further improve the performance and to finalize the schematics, the PCB layouts, and the power supply constructions. The two types of the power supplies share the majority of the designs and features, with minor differences for the different bandwidth requirement. This paper presents the preliminary design, the key power supply functions and features, and the test results.

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WEPMF012

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

cavity, 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.

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WEPMF022

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

cavity, simulation, 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.

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WEPMF042

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

cavity, SRF, 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.

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WEPMF043

Frequency Tuner Development at Cornell for the RAON Half Wave Resonators

cavity, cryogenics, cryomodule, controls

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.

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WEPMF053

XFEL Modulators with Pulse Cables

FEL, klystron, linac, radiation

2487

H.-J. Eckoldt, S. Choroba, T. Grevsmühl, A. Hauberg, J. Havlicek, N. Heidbrook, K. Machau, N. Ngada
DESY, Hamburg, Germany
M. Frei, S.G. Keens, T.H. Strittmatter
Ampegon AG, Turgi, Switzerland
H. Leich
DESY Zeuthen, Zeuthen, Germany

The modulators of the European XFEL produce high voltage, at the 10kV level, having a power of up to 16.8 MW for 1.54 ms. The operation frequency of the super-conducting inac is 10 Hz. The series production of the 29 modulators started in 2012. The first modulator began operation in 2014 and the start of linac was beginning 2017. The R&D phase for the modulators started directly with the development of superconducting cavities. Besides the pulse generation, the modulator had to suppress the 10 Hz repetition rate in order not to disturb the grid. Another unique demand was the development of pulse cables. Since the power RF had to be generated in the tunnel, the klystrons were installed near the cavities. However, the modulators had to be installed outside of the tunnel for space, maintenance reasons and radiation concerns. This transmission of high power pulses via long cables is unique in the world and the suppression of EMI effects was mandatory. During the first year operation no EMI disturbances of other systems were detected and the modulator system works as expected.

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WEPMF054

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

controls, LLRF, cavity, hardware

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.

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WEPMF055

The REGAE Accelerator Vacuum System

gun, vacuum, cathode, electron

2493

S. Lederer, K. Flöttmann, L. Lilje, N. Plambeck
DESY, Hamburg, Germany

Since 2011 the Relativistic Electron Gun for Atomic Exploration (REGAE) is operated at DESY in Hamburg. The accelerator consists mainly of a high gradient S-band RF-gun, which generates ultra-low emittance electron bunches, and an S-band RF-buncher cavity for bunch compression. In this contribution we describe the vacuum system of the REGAE accelerator. We will cover design aspects, applied cleaning and installation procedures as well as operation experience over the last years.

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WEPMF056

Cs2Te Photocathode Lifetime at Flash and European XFEL

cathode, FEL, laser, gun

2496

S. Lederer, S. Schreiber
DESY, Hamburg, Germany

The photo-injectors of FLASH and the European XFEL at DESY (Hamburg, Germany) use Cs2Te photocathodes. In this contribution we give an update on the lifetime and quantum efficiency of the cathodes operated in both facilities. Cathode #680.1 was operated at the European XFEL from the injector commissioning to the first user run for over 700 days. At FLASH cathode #73.3 has been operated with a record of more than 1000 days.

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WEPMF057

PETRA III Vacuum System - Experiences from the First Decade of Operation

vacuum, radiation, photon, experiment

2499

L. Lilje, R. Bospflug, N. Plambeck
DESY, Hamburg, Germany

In 2008 the construction of the PETRA III vacuum system started. A year later the first photons were delivered to initial experiments and in 2010 the user operation started. In this paper the operation of the vacuum system will be reviewed. Some of the lessons learned in the initial phase will be presented as well as the main upgrades since then. By now the vacuum system has shown a very high reliability and shows no significant impact on the availability of the machine.

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WEPMF062

Simulation of Cavity Conditioning for the Diamond SCRF Cavity

cavity, GUI, coupling, simulation

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.

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WEPMF063

Thyratron Replacement*

klystron, high-voltage, linear-collider, collider

2512

I. Roth, N. Butler, M.P.J. Gaudreau, M.K. Kempkes, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: Funded under US DOE grant no. DE-SC0011292.
Thyratrons are typically used as the switch in high power, short pulse modulators with pulse-forming networks. However, thyratrons have a lifetime of only ten to twenty thousand hours, their reservoir heater voltage needs to be adjusted periodically, and reduced overall demand has led multiple thyratron vendors to slow or cease production. In contrast, solid-state switches have a much longer lifetime, need no maintenance, and are based on widely-available commercial items. Despite these advantages, solid-state devices have not historically seen use, due to limited voltage, current, and risetime. Diversified Technologies, Inc. (DTI) has removed this barrier, having developed, built, and tested a thyratron-replacement switch for SLAC based on an array of series and parallel-connected commercial insulated-gate bipolar transistors (IGBTs). This switch has demonstrated operation at very high voltage and current, meeting the full specifications required by SLAC to completely replace (form-fit-function-interface) the L-4888 thyratron: 48 kV, 6.3 kA, and 1 μs risetime.

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WEPMF064

Daresbury Laboratory Short Pulse Klystron Modulators

klystron, high-voltage, power-supply, factory

2515

C. Chipman, M.P.J. Gaudreau, L. Jashari, M.K. Kempkes, J. Kinross-Wright, R.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA
S.A. Griffiths, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.J. Zhang
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China

Diversified Technologies, Inc. (DTI) has developed a unique short pulse klystron modulator system for the Compact Linear Advanced Research Accelerator (CLARA) Project at Daresbury Laboratory. One unit has been delivered and three more are on contract. This system is based on the combination of a high voltage solid-state switch, with a conventional 1:7 pulse transformer, and a passive pulse corrector with automated adjustment. This unique passive circuitry delivers the extremely flat output pulse required for advanced accelerator applications. The CLARA modulators share design elements with previous DTI modulators which provides both a lower cost and easier to maintain system. The modulators are designed to pulse 80 MW-class klystrons at an avg power of 250 kW and provides adjustable high efficiency operation in the 45 kV to 450 kV range for currents up to 545 A and pulse lengths of 1.5 to 4.0 μs. One key objective of modulator development is optimization of voltage flatness (± 0.02 %), stability (± 0.05 %), and reproducibility (± 0.05 %).

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WEPMF065

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

cavity, coupling, impedance, network

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.

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WEPMF068

Inexpensive Brazeless Accelerator Prototype

gun, cavity, vacuum, 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.

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WEPMF073

Adaptation of the Cryogenic System Capacity for the LHC Dynamic Heat Load - Operational Experience

cryogenics, controls, electron, HOM

2541

K. Brodzinski, B. Bradu, S.D. Claudet, D. Delikaris, L.P. Delprat, G. Ferlin
CERN, Geneva, Switzerland

During second LHC physics operation period (Run2), between 2015 and 2018, the accelerator operation modes and beam parameters have been adapted thus allowing significantly improved integrated luminosity production. Increased energy, intensity and adapted beam operation schemes with 25 ns of inter-bunches spacing have an essential influence on the dynamic heat load generation with direct impact on the cryogenic cooling system. In order to cope with significantly higher than expected beam induced thermal load, the cryogenic system was tuned and optimized to adapt the required refrigeration capacity to the beam operational requirements. The most challenging part of tuning was focused on the dynamic heat load compensation on the beam screens circuits. The paper will provide the overview on the main differences between the theoretical heat load values considered for initial design and the on-line measurements performed on cryogenic LHC sectors. Finally, the paper will summarize the methodology and tools implemented in the cryogenic process control system allowing the highly efficient on-line adaptation of the refrigeration power with respect to the beam induced heat load distribution.

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WEPMF074

High Power Conditioning of X-Band RF Components

vacuum, cavity, 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.

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WEPMF075

Performance Measurements and Analysis of Jitter Like Events for the PS Injection Kicker System

kicker, controls, injection, simulation

2549

A. Ferrero Colomo, J.C.C.M. Borburgh, L. Ducimetière, L.M.C. Feliciano, V. Forte, M.A. Fraser, T. Kramer, L. Sermeus
CERN, Geneva, Switzerland

In the framework of the LIU project, several modifications have been made to the CERN PS injection kicker system during the winter stop 2016-2017 (EYETS). Current waveform and beam-based measurements were carried out in 2017 to validate the implemented design changes by observing the magnetic field impact on the beam. During these long-term measurements, increased values for the rise and fall times were observed when compared to single shot observations of the current waveform. An unknown source of jitter-like pre-firing in the main switch has been identified, creating an additional challenge to meet the already tight system rise and fall time specifications. This paper briefly describes the efforts made to fine tune the pulse generator after the EYETS, summarises the optimised configuration and analyses the observed jitter events. A new triggering system design is briefly outlined to address the issue.

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WEPMF079

Experimental Modal Analysis of Lightweight Structures used in Particle Detectors: Optical non-contact Method

laser, experiment, detector, GUI

2565

M. Guinchard, M. Angeletti, F.B. Boyer, A. Catinaccio, C.G. Gargiulo, L.L. Lacny, E.L. Laudi, L.S. Scislo
CERN, Geneva, Switzerland

CERN's specialized structures such as particle detectors are built to have high rigidity and low weight, which comes at a cost of their high fragility. Shock and vibration issues are a key element for their successful transport, handling operations around the CERN infra-structure, as well as for their operation underground. The experimental modal analysis measurement technique is performed to validate the Finite Element Analysis in the case of complex structures (with cables and substructure coupling). In the case of lightweight structures, standard contact measurements based on accelerometers are not possible due to the high mass ratio between the accelerometers and the structure itself. In such a case, the vibration of the structure can be calculated based on the Doppler shift of the laser beam reflected off the vibrating surface. This paper details the functioning and application of an advanced laser-scanning vibrometry system, which utilizes the fore-mentioned non-contact method. The results of the Experimental Modal Analysis of selected lightweight structure using this instrument is also presented and discussed.

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WEPMF080

Investigation and Estimation of the LHC Magnet Vibrations Induced by HL-LHC Civil Engineering Activities

civil-engineering, network, experiment, monitoring

2568

M. Guinchard, M. Cabon, C. Charrondière, K. Develle, P. Fessia, L.L. Lacny, J.A. Osborne, L.S. Scislo, J. Wenninger
CERN, Geneva, Switzerland

HL-LHC requires the excavation of large underground infrastructures in order to host new equipment. The tunnel shall be ready for installation for LS3 (2022) and therefore its construction shall take in place in parallel with the LHC exploitation. Effect of vibrations induced by civil engineering activities need to be evaluated in order to take required corrective actions. For this purpose, several diverse measurements and experiments have been performed in order to estimate the vibration sources and determine the vibration transfer path through the floor and the structure. The transfer functions from amplitude and phase point of view were determined through molasses rock, for both horizontal and vertical vibrations, with dedicated tools and Experimental Modal Analysis was carried out on mechanical structure. The campaign of measurements have been used to confirm the effect of the surface induced vibration on the circulating beam orbit at the resonance frequencies of the structure. This paper reviews the advanced technique of measurements, results and the conclusion about the impact of operating civil engineering machines (road header, hydraulic hammer) during beam exploitation.

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WEPMF086

Eradication of Mercury Ignitron from the 400 kA Magnetic Horn Pulse Generator for CERN Antiproton Decelerator

proton, antiproton, target, kicker

2586

V. Namora, M. Calviani, L. Ducimetière, P. Faure, L.E. Fernandez, G. Gräwer, V. Senaj
CERN, Geneva, Switzerland

The CERN Antiproton Decelerator (AD) produces low-energy antiprotons for studies of antimatter. A 26 GeV proton beam impacts the AD production target which produces secondary particles including antiprotons. A magnetic Horn (AD-Horn) in the AD target area is used to focus the diverging antiproton beam and increase the antiproton yield enormously. The horn is pulsed with a current of 400 kA, generated by capacitor discharge type generators equipped with ignitrons. These mercury-filled devices present a serious danger of environmental pollution in case of accident and safety constraints. An alternative has been developed using solid-state switches and diodes. Similar technology was already implemented at CERN for ignitron eradication in the SPS Horizontal beam dump in the early 2000s. A project was launched to design and set up a full-scale test-bench, to install and test a dedicated solid-state solution. Following the positive results obtained from the test-bench, the replacement of ignitrons by solid-state devices in the operational AD-Horn facility is currently under preparation. This paper describes the test-bench design and results obtained for this very high current pulser.

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WEPMF090

Upgrade of the CMS Experimental Beam Vacuum During LS2

vacuum, experiment, detector, luminosity

2596

J.S. Sestak, G. Bregliozzi, P. Chiggiato, C. Di Paolo
CERN, Geneva, Switzerland

Starting from December 2018, the Large Hadron Collider (LHC) is going to interrupt its physic operations for more than two years within the period called second long shutdown (LS2). The Compact Muon Solenoid (CMS) experiment will undergo the biggest upgrade of its experimental beam vacuum system since the first operations in 2008. The new experimental vacuum layout should comply with demanding structural, vacuum, integration and physics requirements. Moreover, the new layout should be compatible with foreseen engineering changes of the detector and the machine during the upgrade phase of High-Luminosity LHC in LS3. This paper gives an overview of the CMS LS2 experimental vacuum sectors upgrades. Both design and production phase of the new vacuum layout is discussed in detail.

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WEPMG001

Engineering Design and Prototyping of the New LIU PS Internal Beam Dumps

simulation, vacuum, interface, proton

2600

G. Romagnoli, J.A. Briz Monago, M.E.J. Butcher, M. Calviani, D.G. Cotte, Y. C. Coutron, J.J. Esala, E. Grenier-Boley, J. Hansen, A. Huschauer, A. Masi, F.-X. Nuiry, D. Steyart, V. Vlachoudis
CERN, Geneva, Switzerland

For the LHC Injectors Upgrade (LIU) at CERN, the two Proton Synchrotron (PS) internal dumps are redesigned and upgraded for the new high intensity/brightness beams. The dumps are installed as active elements in the lattice in straight sections between the main bending magnets. The dumps are moved into the beam when requested by operation and shave the circulating beam turn by turn stopping the beam after about 6 ms. The shaving induces a very localized beam energy deposition on the dump surface in a thickness of tens of microns. A completely new approach has been developed with FLUKA to simulate beam shaving, coupled with ANSYS to define a new dump core design. This paper presents the design of the dump based on operational constraints such as cycling 200 000 times per year for 20 years, limited access for maintenance or reaching the beam trajectory in 150 ms. These constraints had a major impact on the technological choices. The new dump core is made of a low-density graphite block followed by a denser copper alloy (CuCr1Zr) one. Water circuits, bonded with Hot Isostatic Pressing, are cooling the core in ultra-high vacuum. The core is moved by a spring-based actuation mechanism.

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WEPMG002

Beam Dump Facility Target: Design Status and Beam Tests in 2018

target, radiation, experiment, simulation

2604

E. Lopez Sola, O. Aberle, P. Avigni, L. Bianchi, J. Busom, M. Calviani, M. Casolino, J.P.C. Espadanal, M.A. Fraser, S. Girod, B. Goddard, D. Grenier, M. Guinchard, C. Heßler, R. Illan Fiastre, R. Jacobsson, M. Lamont, A. Ortega Rolo, B. Riffaud, G. Romagnoli, L. Zuccalli
CERN, Geneva, Switzerland

The Beam Dump Facility (BDF) Project, currently in its design phase, is a proposed general-purpose fixed target facility at CERN, dedicated to the Search for Hidden Particles (SHiP) experiment in its initial phase. At the core of the installation resides the target/dump assembly, whose aim is to fully absorb the high intensity 400 GeV/c SPS beam and produce charmed mesons. In addition to high thermo-mechanical loads, the most challenging aspects of the proposed installation lie in very high energy and power density deposition that are reached during operation. In order to validate the design of the BDF target, a scaled prototype is going to be tested during 2018 in the North Area at CERN, upstream the existing beryllium primary targets. The prototype testing under representative beam scenarios will allow having an insight of the material response in an unprecedented regime. Online monitoring and an extensive Post Irradiation Experimental (PIE) campaign are foreseen. The current contribution will detail the design and handling aspects of the innovative Target Complex as well as the design of the BDF target/dump core and the design and construction of the prototype target assembly.

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WEPMG003

Analysis and Operational Feedback of the New High-Energy Beam Dump in the CERN SPS

MMI, simulation, shielding, monitoring

2608

A. Perillo-Marcone, M. Calviani, R. Illan Fiastre, P. Rios Rodriguez, G. Romagnoli
CERN, Geneva, Switzerland

The CERN Super Proton Synchrotron (SPS) high-energy internal dump (TIDVG) is used to intercept beam dumps from 10².2 to 450 GeV. An inspection in 2013 revealed significant beam induced damage to the aluminium absorbing block, resulting in operational limitations to minimize the risk of reproducing this phenomenon. Additionally, in 2016 a vacuum leak was detected in the dump assembly, which imposed further limitations, i.e., a reduction of the beam intensity that could be dumped. In the winter stop of 2016-2017, a new version of the TIDVG (featuring several design modifications) was installed. This paper analyses the performance of the dump observed during the commissioning period and subsequent operation in 2017 of the most recent installed version of the TIDVG. The temperature measurements recorded during this time were used to benchmark numerical models that allow predicting the performance of the dump under different conditions. After several iterations, a good agreement between simulations and real measurements was obtained; resulting in numerical models that can produce reliable results for this and other devices with similar design.

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WEPMG004

Design of the Future High Energy Beam Dump for the CERN SPS

shielding, dumping, simulation, kicker

2612

S. Pianese, J.A. Briz Monago, M. Calviani, D. Grenier, P.B. Heckmann, J. Humbert, R. Illan Fiastre, A. Perillo-Marcone, G. Romagnoli, S. Sgobba, D. Steyart, V. Vlachoudis
CERN, Geneva, Switzerland

The future CERN Super Proton Synchrotron (SPS) internal dump (Target Internal Dump Vertical Graphite, known as TIDVG#5), to be installed during CERN's Long Shutdown 2 (2019-2020), will be required to intercept beam dumps from 26 to 450 GeV, with increased intensity and repetition rates with respect to its predecessor (TIDVG#4). The beam power to be managed by the dump will increase by approximately a factor of four; resulting in new challenges in terms of design in order to fulfil the highly demanding specification, which is based on guaranteeing a good performance of the machine with little or no limitations imposed by this device. This paper presents the proposed design, including material selection, manufacturing techniques and thermo-mechanical simulations under different operational scenarios expected during the lifetime of the device.

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WEPMK001

Preliminary Design of a Cooling System for the LHC Injection Kicker Magnets

kicker, injection, vacuum, impedance

2624

L. Vega Cid, M.J. Barnes, L. Ducimetière, M.T. Moester, V. Vlachodimitropoulos, W.J.M. Weterings
CERN, Geneva, Switzerland
A. Abánades
ETSII UPM, Madrid, Spain

The CERN Large Hadron Collider (LHC) is equipped with two fast pulsed magnet systems (MKIs) that inject particle beams from the injector chain. Future operation for High Luminosity LHC (HL-LHC) with high intensity beams will cause heating of the ferrite yokes of the MKIs beyond their Curie temperature, preventing injection until the yokes cool down. Beam coupling impedance studies show that it is possible to move a substantial portion of the beam induced power deposition from the upstream ferrite yokes, which are the yokes with the highest power deposition, to ferrite rings located at the upstream end of the magnet. Thermal predictions show that this power redistribution, combined with the installation of a cooling system around the rings, will maintain the temperatures of all the yokes and ferrite rings below their Curie point. Since the rings are not pulsed to high voltage, whereas the ferrite yokes are, the installation of a cooling system is feasible around the rings. The proposed design of the cooling system will be tested to ensure good performance before its installation on the MKIs. The details of the simulations and the design process are reported.

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WEPMK005

Preliminary Results from Validation Measurements of the Longitudinal Power Deposition Model for the LHC Injection Kicker Magnet

impedance, kicker, injection, coupling

2636

V. Vlachodimitropoulos, M.J. Barnes, A. Chmielinska
CERN, Geneva, Switzerland
A. Chmielinska
EPFL, Lausanne, Switzerland

During Run 1 of the LHC, one of the injection kicker magnets (MKIs) exhibited an excessively high ferrite temperature, caused by coupling of the high intensity beam to the real impedance of the magnet. Beam-screen upgrades, implemented during Long Shutdown 1 (LS1), have been very effective in reducing beam coupling impedance and since then the MKIs have not limited LHC's availability. However, temperature measurements during operation have shown that one end of the MKI's ferrite yoke is consistently hotter than the other. Detailed simulation models and data post-processing algorithms have been developed to understand and mitigate the observed behaviour. In the present paper, the model used to obtain the power loss distribution along the magnet is presented. The model is subsequently applied to two MKI design configurations under study: (i) the one currently in operation and (ii) an upgraded magnet that was installed in the LHC tunnel during the Year End Technical Stop (YETS) 2017/18. In order to validate the expected behaviour a novel measurement technique was developed, applied in both configurations and compared to predictions. The results obtained are reported and conclusions regarding the effectiveness of the design are drawn.

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WEPMK007

INFN-LASA Design and Prototyping Activity for PIP-II

cavity, HOM, coupling, 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.

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WEPML008

Tuner Testing of a Dressed 3.9 GHz Cavity for LCLS-II at Fermilab

cavity, SRF, 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.

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WEPML009

Superconducting Magnet Performance in LCLS-II Cryomodules

cryomodule, quadrupole, superconducting-magnet, dipole

2693

V.S. Kashikhin, S. Cheban, J. DiMarco, E.R. Harms, A.V. Makarov, T. Strauss, M.A. Tartaglia
Fermilab, Batavia, Illinois, USA

Abstract' New LCLS-II Linear Superconducting Accelerator Cryomodules under construction at Fermilab. Inside each SCRF Cryomodule installed superconducting magnet package to focus and steer an electron beam. The magnet package has the iron dominated configuration with racetrack type quadrupole and dipole conductively cooled coils. For easier installation the magnet could be split in the vertical plane. Initially the magnet was tested in a liquid helium bath, and were performed high precision magnetic field measurements. Several Cryomodules with magnets inside were built and successfully tested at Fermilab test facility. In the paper presented Cryomodule magnet packages test results, discussed the magnet, and current leads conduction cooling performance.

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WEPML010

Operation Regime Analysis of Conduction Cooled Cavities Through Multi-Physics Simulation

cavity, 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.

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WEPML023

Design and Test Results of the 3.9 GHz Cavity for LCLS-II

cavity, radiation, cryomodule, 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.

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WEPML025

Advantages and Challenges of Nb3Sn Superconducting Undulators

undulator, site, experiment, photon

2734

A.V. Zlobin, E.Z. Barzi, D. Turrioni
Fermilab, Batavia, Illinois, USA
Y. Ivanyushenkov, I. Kesgin
ANL, Argonne, Illinois, USA

Funding: This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Superconducting undulators (SCUs) employ superconducting coils, and due to high critical current density in a superconductor, outperform undulators based on permanent magnets in terms of the level of magnetic field. So far, most of the SCUs, including devices built at Advanced Photon Source (APS), use Nb-Ti superconductor. Utilization of Nb3Sn conductor offers a possibility to increase the undulator field even further but requires to overcome certain challenges that are described in this paper. Based on experience of developing Nb3Sn accelerator magnets at Fermi National Accelerator Laboratory, possible solutions are discussed. The achievable field levels for Nb3Sn version of existing APS and the future APS-Upgrade superconducting undulators are also presented and discussed.

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WEPML026

Large-Aperture High-Field Nb3Sn Dipole Magnets

dipole, collider, luminosity, magnet-design

2738

A.V. Zlobin, V.V. Kashikhin, I. Novitski
Fermilab, Batavia, Illinois, USA

Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
Large-aperture high-field dipole magnets based on Nb3Sn superconductor are necessary for various accelerator systems of future hadron and muon colliders. In hadron colliders, they are used needed for beam separation before and after interaction points. In a muon collider, they are considered for both the arc and the interaction regions to provide room for internal absorbers protecting magnets from the muon decay products. These magnets can also be used in test facilities to produce a background magnetic field for testing conductor samples or insert coils. High level of magnetic field and large aperture size lead to large Lorentz forces and mechanical strains and stresses which can damage brittle Nb3Sn coils. This paper describes conceptual designs of 120-mm aperture dipoles with magnetic fields up to 15 T based on cos-theta coils. Stress management technique and magnet parameters are also presented and discussed.

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WEPML030

First Tests of the Main Quadrupole and Corrector Magnets for the SIS100 Synchrotron of FAIR

quadrupole, sextupole, dipole, cryogenics

2751

E.S. Fischer, A. Bleile, V.I. Datskov, V.M. Marusov, J.P. Meier, C. Omet, P.J. Spiller, K. Sugita
GSI, Darmstadt, Germany
P.G. Akishin, V.V. Borisov, H.G. Khodzhibagiyan, S.A. Kostromin, D.N. Nikiforov, M.M. Shandov, A.V. Shemchuk
JINR, Dubna, Moscow Region, Russia

The heavy ion synchrotron SIS100 is the main accelerator of the FAIR complex (Facility for Antiproton and Ion Research) in Darmstadt, Germany. Currently the construction site and facility are advancing fast. The series production of the main dipoles was already started in 2017. In parallel, the first two quadrupoles, a chromaticity sextupole and a steerer were built and tested in cooperation between GSI and JINR at the cryogenic test facility in Dubna. We present the operation performance of these two first of series quadrupole units (consisting both of a corrector magnet mechanically and hydraulically combined with a quadrupole). Besides the thermal stability of the fast ramped superconducting magnets special attention is directed to their magnetic field properties. The obtained results provide the basis for starting the series production of all SIS100 quadrupole and corrector magnets in 2018.

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WEPML031

The New Broadband Accelerating System for the SIS18 Upgrade at GSI

cavity, 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.

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WEPML033

The FAIR-SIS100 Accelerating RF Station

cavity, controls, feedback, 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.

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WEPML034

Design and Commissioning of the RF System of the Collector Ring at FAIR

controls, power-supply, cavity, MMI

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.

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WEPML035

Superconducting Dipoles for SIS100

dipole, synchrotron, controls, superconducting-magnet

2768

C. Roux, P. Aguar Bartolome, A. Bleile, E.S. Fischer, G. Golluccio, F. Kaether, J. Ketter, J.P. Meier, A. Mierau, C. Omet, P.J. Spiller, K. Sugita, P.B. Szwangruber, A. Warth, H.G. Weiss
GSI, Darmstadt, Germany

The international facility for antiproton and ion research (FAIR) is currently being developed in Darmstadt, Germany, for fundamental research in various fields of modern physics. Its main accelerator, the SIS100 heavy ion synchrotron, utilizes fast-cycling superconducting magnets operated at cryogenic temperatures. An intense measurement program of first of series (FoS) module revealed excellent behaviour with respect to, e.g., quench performance and AC losses. With an optimized fabrication technique, the geometrical accuracy was improved to be sufficient to provide a highly homogeneous field. Consequently, the series production of 110 dipoles was released. First significant results on the reproducibility and the variation of physical properties along the series production gained at the test facility of GSI are presented.

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WEPML051

Improvement of the Chopper System for rf Deflector at the J-PARC Linac

controls, timing, cavity, linac

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.

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WEPML057

First Commissioning of Vacuum System of Positron Damping Ring for SuperKEKB

photon, vacuum, MMI, positron

2826

K. Shibata, H. Hisamatsu, T. Ishibashi, K. Kanazawa, M. Shirai, Y. Suetsugu, S. Terui
KEK, Ibaraki, Japan

To satisfy the requirements of high beam quality for positron injection into the SuperKEKB main ring, a new damping ring (DR) is constructed in an upgraded injector system. The DR is a racetrack-shaped storage ring with a circumference of 135.5 m, in which the 1.1 GeV positron beam is stored for 40 ms to damp the emittance. The maximum stored beam current is 70.8 mA. Required beam lifetime due to residual gas scattering is longer than 1000 s and the average pressure should be lower than 10^-5 Pa. Non-evaporable getter (NEG) pumps are mainly used, and the average effective pumping speed for CO is expected to be 0.013 m3s⁻¹m-1 immediately after NEG activation. The beam pipes are made of aluminum alloy, and have antechambers to deal with synchrotron radiation (critical energy 0.8-0.9 keV, total power 7.2 kW) in arc sections, which are effective in reducing the electron cloud and the impedance of the beam pipes. As additional countermeasures against the electron cloud effect, TiN coating and grooved surfacing are also adopted. The commissioning of the DR will commence at the beginning of 2018. The status of the vacuum system of the DR during the first commissioning will be reported.

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WEPML058

Observation of Pressure Bursts in the SuperKEKB Positron Ring

MMI, positron, luminosity, electron

2830

S. Terui, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, Y. Suetsugu
KEK, Ibaraki, Japan

The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8x10³⁵ cm^-2 s^-1 using a nano-beam scheme. In the Phase 1 commissioning from February to June, 2016, the vacuum system of the main ring worked well as a whole at stored beam currents of approximately 1 A. However, the localized pressure bursts accompanied by beam losses were observed in the positron ring. The beam loss monitors triggered beam aborts, and the phenomena has became an obstacle to the beam commissioning. These pressure bursts were frequently observed from the early stage of the commissioning. Most of the pressure bursts occurred near or inside of aluminum-alloy beam pipes in dipole magnets, which have grooved surface at the top and bottom sides. The various observations indicates that the most probable cause of this phenomenon was the collision between the dusts dropped from the grooves and the circulating positron beam. We report the properties and the probable causes of the pressure bursts, and the possible mitigation methods. Some results of the countermeasures taken prior to the ongoing Phase-2 commissioning will be also presented.

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THXGBD3

Status of the ESRF-Extremely Brilliant Source Project

SRF, vacuum, injection, dipole

2882

J.-L. Revol, C. Benabderrahmane, P. Berkvens, J.C. Biasci, J-F. B. Bouteille, T. Brochard, N. Carmignani, J.M. Chaize, J. Chavanne, F. Cianciosi, A. D'Elia, R.D. Dimper, M. Dubrulle, D. Einfeld, F. Ewald, L. Eybert, G. Gautier, L. Goirand, L. Hardy, J. Jacob, B. Joly, M.L. Langlois, G. Le Bec, I. Leconte, S.M. Liuzzo, C. Maccarrone, T.R. Mairs, T. Marchial, H.P. Marques, D. Martin, J.M. Mercier, A. Meunier, M. Morati, J. Pasquaud, T.P. Perron, E. Plouviez, E. Rabeuf, P. Raimondi, P. Renaud, B. Roche, K.B. Scheidt, V. Serrière, P. Van Vaerenbergh, R. Versteegen, S.M. White
ESRF, Grenoble, France

The ESRF - the European Synchrotron Radiation Facility - is a user facility in Grenoble, France, and the source of intense high-energy (6 GeV) X-rays. In 2019, the existing storage ring will be removed and a new lattice will be installed in its place, dramatically reducing the equilibrium horizontal emittance. This 'fourth-generation' synchrotron will produce an X-ray beam 100 times more brilliant and coherent than the ESRF source today. The Extremely Brilliant Source (EBS) project was launched in 2015 and is now well underway, on track for its scheduled completion in 2020. The design is completed, the procurement in full swing, the assembly has started, and critical installation activities are being prepared. The current status, three years into the project, will be revealed, along with the expected performance of the accelerator and the technical challenges involved. This paper will focus on the implementation of the project.

Slides THXGBD3 [13.547 MB]

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THXGBF2

Beam Commissioning of the IFMIF EVEDA Very High Power RFQ

rfq, cavity, MMI, vacuum

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]

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THYGBF1

High Power Beam Operation of the J-PARC RCS and MR

extraction, emittance, quadrupole, betatron

2938

Y. Sato
KEK, Ibaraki, Japan

This invited talk presents the most recent status of improving J-PARC main ring (MR) beam operation together with the rapid cycling synchrotron (RCS) effort. The RCS has optimized the beam performance for the MR injection as well as the muon and neutron targets, where each requires different emittance and beam halo size. The MR has two extraction modes; fast extraction (FX) for the long baseline neutrino oscillation experiment, T2K, and slow extraction (SX) for experiments in the hadron experimental facility. At present, achieved beam intensities are 2.4·10¹⁴ protons per pulse (ppp) with cycle time 2.48 s (470 kW) in the FX mode and 5.10¹³ ppp with cycle time 5.52 s (44 kW) in the SX mode. For the FX operation, recent improvements are settings of new betatron tune, corrections of resonances near the betatron tune, and adopting 2nd harmonic rf voltage to reduce space charge effect. Beam instabilities have been suppressed with controlling chromaticity correction and transverse feedback systems. For the SX mode, a dynamic bump scheme for reducing extracted beam loss is successfully adopted. A high extraction efficiency of 99.5 % is achieved at the 44 kW beam operation.

Slides THYGBF1 [6.664 MB]

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THYGBF2

PIP-II Injector Test Warm Front End: Commissioning Update

kicker, rfq, emittance, focusing

2943

L.R. Prost, R. Andrews, C.M. Baffes, J.-P. Carneiro, B.E. Chase, A.Z. Chen, E. Cullerton, P. Derwent, J.P. Edelen, J. Einstein-Curtis, D. Frolov, B.M. Hanna, D.W. Peterson, G.W. Saewert, A. Saini, V.E. Scarpine, A.V. Shemyakin, V.L. Sista, J. Steimel, D. Sun, A. Warner
Fermilab, Batavia, Illinois, USA
C.J. Richard
NSCL, East Lansing, Michigan, USA
V.L. Sista
BARC, Mumbai, India

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 Warm Front End (WFE) of the Proton Improvement Plan II Injector Test [1] at Fermilab has been constructed to its full length. It includes a 15-mA DC, 30-keV H⁻ ion source, a 2 m-long Low Energy Beam Transport (LEBT) with a switching dipole magnet, a 2.1 MeV CW RFQ, followed by a Medium Energy Beam Transport (MEBT) with various diagnostics and a dump. This report presents the commissioning status, focusing on beam measurements in the MEBT. In particular, a beam with the parameters required for injection into the Booster (5 mA, 0.55 ms macro-pulse at 20 Hz) was transported through the WFE.

Slides THYGBF2 [2.434 MB]

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THYGBF3

Challenges of FAIR Phase 0

controls, MMI, experiment, storage-ring

2947

M. Bai, A. Adonin, S. Appel, R. Bär, M.C. Bellachioma, U. Blell, C. Dimopoulou, G. Franchetti, O. Geithner, P. Gerhard, L. Groening, F. Herfurth, R. Hess, R. Hollinger, H.C. Hüther, H. Klingbeil, A. Krämer, S.A. Litvinov, F. Maimone, D. Ondreka, N. Pyka, S. Reimann, A. Reiter, M. Sapinski, B. Schlitt, G. Schreiber, M. Schwickert, D. Severin, R. Singh, P.J. Spiller, J. Stadlmann, M. Steck, R.J. Steinhagen, K. Tinschert, M. Vossberg, G. Walter, U. Weinrich
GSI, Darmstadt, Germany

After two-year's shutdown, the GSI accelerators plus the latest addition of storage ring CRYRING, will be back into operation in 2018 as the FAIR phase 0 with the goal to fulfill the needs of scientific community and the FAIR accelerators and detector development. Even though GSI has been well known for its operation of a variety of ion beams ranging from proton up to uranium for multi research areas such as nuclear physics, astrophysics, biophysics, material science, the upcoming beam time faces a number of challenges in re-commissioning its existing circular accelerators with brand new control system and upgrade of beam instrumentations, as well as in rising failures of dated components and systems. The cycling synchrotron SIS18 has been undergoing a set of upgrade measures for fulfilling future FAIR operation, among which many measures will also be commissioned during the upcoming beam time. This paper presents the highlights of the challenges such as re-establishing the high intensity heavy ion operation as well as parallel operation mode for serving multi users. The status of preparation including commissioning results will also be reported.

Slides THYGBF3 [2.948 MB]

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THPAF030

PETRA III Storage Ring Performance Improvement Based on Multi-Objective Genetic Algorithms (MOGA)

injection, storage-ring, multipole, dynamic-aperture

3018

X.N. Gavaldà, J. Keil, G.K. Sahoo, R. Wanzenberg
DESY, Hamburg, Germany

The performance of the 3th generation light sources relies on the beam lifetime and the injection efficiency, both related with the beam dynamic properties of the storage ring as momentum acceptance and dynamic aperture, respectively. High values of beam lifetime and injection efficiency are desirable to reduce the storage ring instabilities during injection, the radiation losses and the energy consumption of the facility. This paper reports the first application of Multi-Objective Genetic Algorithms (MOGA) to optimize the linear and non-linear beam dynamics of PETRA III storage ring. Genetic algorithms are a heuristic search that mimics the process of natural evolution to optimize problems with a high level of complexity, as in the case of PETRA III storage ring composed by hundreds of magnets. This computational method uses hundreds of CPUs. MOGA is used to maximize the dynamic aperture and the momentum acceptance finding new combinations of quadrupole and sextupole settings in a multi-dimensional parameter space maintaining the solutions in the level of ten picometers.

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THPAF057

Instability Observations in the Large Hadron Collider During Run 2

coupling, simulation, electron, hadron

3099

L.R. Carver, D. Amorim, S. A. Antipov, N. Biancacci, X. Buffat, G. Iadarola, K.S.B. Li, E.H. Maclean, L. Mether, E. Métral, B. Salvant, M. Schenk
CERN, Geneva, Switzerland
L. Mether, M. Schenk
EPFL, Lausanne, Switzerland

Instabilities of many different types and characteristics have been observed in the LHC during Run 2. The origin of these instabilities come from a variety of stabilising and destabilising mechanisms. Efforts to understand these instabilities and prevent their occurrence has improved the performance of the LHC in all stages of the machine cycle. This paper aims to give an overview into some of the instability observations and details the operational steps to prevent them.

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THPAF058

Experimental Characterisation of a Fast Instability Linked to Losses in the 16L2 Cryogenic Half-Cell in the CERN LHC

MMI, electron, monitoring, pick-up

3103

B. Salvant, S. A. Antipov, G. Arduini, N. Biancacci, X. Buffat, L.R. Carver, P. Collier, A.A. Gorzawski, W. Höfle, G. Iadarola, G. Kotzian, A. Lechner, T.E. Levens, D. Mirarchi, E. Métral, G. Rumolo, D. Valuch
CERN, Geneva, Switzerland
L. Mether
EPFL, Lausanne, Switzerland

The operation during the summer months of the 2017 Run of the CERN LHC was plagued with fast beam losses that repeatedly occurred in the 16th arc half-cell at the left of IP2 as well as in the collimation insertion, leading to unwanted beam dumps. Transverse coherent oscillations were observed during this fast process. We detail here the experimental observations of coherent motion that al-lowed shedding light upon parts of the mechanism and identify the potential mitigations that were successfully implemented in the second half of the Run.

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THPAF086

Beam Dynamics Simulations for Operating a Robinson Wiggler at the MLS

wiggler, optics, dynamic-aperture, storage-ring

3189

J. Li, J. Feikes, M. Ries
HZB, Berlin, Germany
T. Tydecks
CERN, Geneva, Switzerland

A Robinson wiggler is planned to be installed in the storage ring of the Metrology Light Source (the MLS). The Robison wiggler (RW) is a device consisting of a chain of combined-function magnets (CFMs), intended to manipulate the damping partition numbers and thus adjust the longitudinal emittance. The objective is to lengthen the bunch in order to improve the Touschek lifetime. However, the nonlinear perturbation of the beam dynamics due to the Robinson wiggler could limit the achievable improvement. Therefore, a symplectic method of modeling the wiggler has been established to study these nonlinear effects. Optimized solutions have been developed for both the ramping procedure and the future daily operation of the wiggler and are presented in this paper.

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THPAK014

Analytical Estimation of the Beam Ion Instability in HEPS

simulation, brightness, damping, electron

3231

N. Wang, Z. Duan, S.K. Tian, H.S. Xu
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a new designed photon source at beam energy of 6 GeV, with natural beam emittance less than 100pm. Due to the small transverse beam size, beam ion instability is one of the potential issues for HEPS. The growth time of the instability is estimated analytically for different operation scenarios. The results show considerably good agreement with the wake strong simulations.

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THPAK020

Optics Model and Measurements of the DAΦNE Transfer Lines

injection, optics, dipole, positron

3249

O.R. Blanco-García, A. De Santis, G. Di Pirro, C. Milardi, D. Pellegrini, A. Stecchi, A. Stella
INFN/LNF, Frascati (Roma), Italy

The different components of the DAΦNE accelerator complex: LINAC, Damping Ring and two colliding rings are connected by a composite system of Transfer Lines which, thanks to adaptive configurations, are able to transport electron and positron beams at 510~MeV. Recently, thanks to the introduction of new diagnostics tools, the optics model of the DAΦNE Transfer Lines has been improved and succesfully used to make the collider operations more efficient. The measurements done by using the new tools and their impact on the optics model optimization process are presented and discussed.

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THPAK045

Summary of Beam Operation Capability at FXR LIA

cathode, electron, induction, experiment

3316

Y.H. Wu, J. Ellsworth
LLNL, Livermore, California, USA

Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52- 07NA27344.
In this paper we summarize the current beam operation capability of FXR linear induc-tion accelerator (LIA) at LLNL. Experi-mental measurements for electron beam pa-rameters at different beam operations are pre-sented.

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THPAK054

Optics Calibration and Measurement for Low Alpha Lattices in TPS Storage Ring

lattice, emittance, optics, coupling

3343

F.H. Tseng, C.H. Chen, J.Y. Chen, P.C. Chiu, C.H. Huang, C.-C. Kuo, C.C. Liang, C.Y. Liao, Y.-C. Liu, H.-J. Tsai
NSRRC, Hsinchu, Taiwan

In order to provide short-pulse radiation for pump-probe experiments and coherent radiation for THz/IR measurements, we develop low alpha lattices to reduce the momentum compaction factor from nominal operation values 2.4*10^-4 to 2.6*10-5 or lower. The corresponding bunch length at 2.8 MV RF voltage and zero current are from 10.78 ps to 3.55 ps or less. In the low alpha operations, the bunch lengthening as a function of bunch current, the orbit drift and noise enhancements as well as rf stability effect are observed. In this report we will present our studies on the lattice design, optics correction, beam parameters measurements and alpha measurements.

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THPAK134

Dynamic Equations: The Matrix Representation of Beam Dynamic Equations Instead of Tensor Description

controls, sextupole, software, octupole

3554

S.N. Andrianov, A.N. Ivanov, N.V. Kulabukhova
St. Petersburg State University, St. Petersburg, Russia
Chang, S. Chang
KAIST, Daejeon, Republic of Korea
J. Choi
CAPP/IBS, Daejeon, Republic of Korea
E. Krushinevskii, E. Sboeva
Saint Petersburg State University, Saint Petersburg, Russia

In this paper we consider mathematical and computer modeling of nonlinear dynamics of particle beams in cyclic accelerators in terms of the matrix representation of the corresponding nonlinear differential equations. The proposed approach is different from the usual presentations of non-linear equations in the form of Taylor series. In the paper, we use the coefficients representation in the form of two-dimensional matrices. The similar approach allows us not only to significantly reduce the time spent on modeling beam dynamics but use symbolic mathematics to calculate the necessary two-dimensional matrices. This method demonstrates the effectiveness when solving problems of dynamics problems and optimization of control systems, and for evaluating the influence of various effects on the dynamics of the beam (including taking into account the spin). Using the tools of symbolic computations not only significantly increases the computational efficiency of the method, but also allows you to create databases of "ready-made" transformations (Lego-objects), which greatly simplify the process of modeling particle dynamics. Examples of solving practical problems are given.

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THPAL002

RF System Operation of High Current RFQ in ADS Project

rfq, cavity, 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.

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THPAL007

Upgrade of PIAVE Superconducting RFQs at INFN-Legnaro

rfq, SRF, cavity, 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.

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THPAL012

Soft Chemical Polishing and Surface Analysis of Niobium Samples

cavity, niobium, SRF, linac

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.

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THPAL023

Assessing the Continued Suitability of an Existing Water System for an Accelerator Upgrade

simulation, neutron, interface, HOM

3673

W.C. Barkley, C.E. Buechler, E.N. Pulliam
LANL, Los Alamos, New Mexico, USA

This paper assesses the continued suitability of an existing Water Cooling System (WCS) for cooling intermediate and high-power RF power amplifiers at the Los Alamos Neutron Science Center (LANSCE). At LANSCE, the high-power and intermediate power amplifiers installed in the 70s were at end-of-life with obsolete parts and no suitable replacements available to extend their life. The LANSCE Refurbishment Project was initiated (now complete) to replace these amplifiers and to utilize already existing WCSs. Two existing WCSs were repurposed and one new WCS was designed and installed. Unscheduled, intermittent water system trips on one of the WCSs has prompted the engineering group to drill down into the original decision, build a flow model and assess some of the legacy components' suitability to solve the problem. This paper discusses the general approach, troubleshooting and solution recommendations to be made for resolution of the intermittent issues.

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THPAL034

Dynamic Tuner Development for Medium β Superconducting Elliptical Cavities

cavity, linac, 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.

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THPAL035

Design of β=0.65, 5 Cells, 644 MHz Elliptical Cavity for FRIB Upgrade

cavity, linac, cryomodule, niobium

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.

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THPAL038

Phase Grouping of Larmor Electrons by a Synchronous Wave in Controlled Magnetrons

controls, electron, cavity, 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.

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THPAL045

Determination of the Electron Bunch Length With Third Harmonic Cavity for the Taiwan Photon Source

cavity, 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.

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THPAL050

Beam Dynamics of the First Beams for the IFMIF-EVEDA RFQ Commissioning

controls, storage-ring, synchrotron, site

3754

C.S. Chen, W.S. Chan, Y.Y. Cheng, Y.-C. Chung, C.Y. Liu, Y.-H. Liu, Z.-D. Tsai
NSRRC, Hsinchu, Taiwan

Since December 31th 2014, the first synchrotron light from Taiwan Photon Source (TPS) was stored in the storage ring, the challenge to operate both Taiwan Light Source (TLS) and TPS smoothly and reliably became a significant issue for all members in NSRRC. On the one hand, the beam quality of former TLS must not been impaired due to the occupied resources by TPS, on the other hand, the most efforts were devoted to achieving steady operation of TPS. In order to operate both ring stably, some mutual backup structures were designed in the compressed air system and the chilled water system between TLS and TPS. The primary advantage of these mutual backup systems is minimizing the risk of beam-trip while any one of the utility system fails. Secondly, the mutual backup structures provide more flexible usage to accomplish energy conservation. From both risk-reduction and energy conservation points of view, the backup systems will do a great deal of good in the future.

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THPAL051

The Data Acquisition on Vibration Evaluation for Ice Water Pumps Systems in TPS

data-acquisition, status, synchrotron, controls

3757

Y.-H. Liu, C.-S. Chen, Y.-C. Chung, Z.-D. Tsai
NSRRC, Hsinchu, Taiwan

The vibration status is a critical problem for the utility system, especially for those continuously operate deionized and cooling water pumps used in synchrotron accelerator. The purpose of this paper is to evaluate the vibration level and spectrum condition for TPS water pump systems. In order to predictive maintenance before pump systems fail, the vibration monitoring system was constructed. After vibration test for several months, the alignment of some of the ice water pumps were found mismatched because of poor system positioning and operate continuously. Besides, the ice water pump were redundantly operated and switch over every Monday morning. The recorded data showed the system sometimes switch fail because of control status or system stability. Thus, the water pump systems were repaired and maintained base on vibration monitoring system. There is still some remain problems for ice water pump systems. The utility systems could prevent malfunction through regular vibration inspection and daily data acquisition.

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THPAL053

Perveance Measurement of the TLS-Linac Klystron and the Evaluation of Its Operation Performance

klystron, electron, cathode, linac

3763

H.H. Chen, C.H. Kuo, K.-K. Lin, Y.-H. Liu
NSRRC, Hsinchu, Taiwan

The high power klystron is a radio frequency amplifier for TLS linac operation. It is a crucial device for electron acceleration in linac. How to evaluate its efficiency, lifetime and performance of klystron in operation is one of the major concern in this report. The key klystron parameter perveance is introduced and used for performance evaluation and operation status monitoring. It is important to execute periodic monitoring on perveance for ensuring a stable linac operation. Klystron characteristics diagnostics can be achieved through perveance measurement. A couple of klystron diagnostic parameters concerning perveance are explored for field examination purpose. Perveance comparison with factory acceptance test data is also presented.

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THPAL054

Modification of a Power Supply for Low-Alpha Operation in the Taiwan Photon Source

power-supply, controls, interface, MMI

3766

Y.S. Wong, Huang, J.C. Huang, C.Y. Liu, K.-B. Liu, B.S. Wang
NSRRC, Hsinchu, Taiwan

In this paper we describe the modifications of power supplies needed to operate the storage ring with a low momentum compaction factor (low alpha) to generate short x-ray pulses. This design includes an external polarity reversal circuit in quadrupole and sextupole magnet power supplies. The polarity reversal circuit contains four relay module where each relay can receive signals from the D-type analog interface. The power supply control system must be enhanced to switch output polarity. The operating principle and analyses of polarity reversal are discussed in more detail. Finally, a prototype polarity reversal circuit with 30 V, 250 A and 7.5 kW output power is implemented in the laboratory to verify the expected performance for the TPS low alpha operation.

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THPAL055

A Novel High Step-down DC-DC Converter with Isolated Transformer and Switched Capacitor Techniques for Corrector Magnet Bulk Power in Taiwan Photon Source

ISOL, power-supply, high-voltage, simulation

3769

Y.S. Wong, K.-B. Liu
NSRRC, Hsinchu, Taiwan
J.F. Chen
NCKU, Tainan city, Taiwan

In this study, a high step down DC-DC converter was successfully integrated using switch capacitor and isolated transformer techniques. Switching capacitor techniques has use of capacitor parallel energy storage and series release of the way to improve the voltage conversion ratio. In addition, the output voltage ripple will be smaller due to the input current being continuous, the inductance is an element to prevent a surge current. The isolated transformer techniques has use of inductor coil turns ratio to achieve high conversion ratio. But, the leakage inductor and parasitic capacitance on the power switch will be resonant to generate a surge voltage spike when the power switch S is turned off. So that, additional a passive clamp circuit, energy of leakage inductor will be recycled to clamp capacitor and voltage stress of main power switch. The power switch S can be selected a lower Rds(on) components and reduce the conduction losses to improve power converter efficiency. Step down mode operation principle and steady-state analysis were discussed in this paper. Finally, simulation and prototype circuit is implemented in this laboratory to verify the performance, the step-down DC-DC converter is input voltage 400-V, output voltage 48-V and output power 960-W.

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THPAL073

Progress on 1.5 GHz Multi-kW CW Amplifier

klystron, HOM, solenoid, insertion

3821

A.V. Smirnov, R.B. Agustsson, S. Boucher, A.Y. Murokh, A.Yu. Smirnov
RadiaBeam Systems, Santa Monica, California, USA
M.A. Ahmadi, P. Blanchard, M.D. Mccann, C. Nguen, P.B. Peter, J. Zabek
Microsemi Corporation, Aliso Viejo, USA
G.R. Branner, K.S. Yuk
UC Davis, Davis, USA
J.J. Hartzell, K.J. Hoyt, T.J. Villabona
RadiaBeam, Santa Monica, California, USA
V. Khodos
Sierra Nevada Corporation, Irvine, USA

Funding: Work supported by the U.S. Department of Energy (award No. DE-SC0013136)
JLab upgrade program foresees new CW amplifiers operating at 1497 MHz and significantly increased efficiency vs. existing VKL-7811 klystron. One of possibilities for the replacement is usage of high electron mobility packaged GaN transistors applied in array of highly efficient amplifiers using precise in-phase, low-loss combiners-dividers. We present here performance of novel, compact 300 W pallets developed at MicroSemi specifically for this project including their new GaN transistor, as well as significantly upgraded divider and combiner. Design features and challenges related to amplifier modules (pallets), broadband 21-way dividers/combiners, as well construction and assembling of the entire system are discussed including measurements.

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THPAL081

A 3 GHz SRF Reduced-beta Cavity for the S-DALINAC

cavity, linac, SRF, 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.

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THPAL086

Superconducting Thin Film RF Measurements

cavity, SRF, vacuum, niobium

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.

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THPAL089

Design, Assembly and Commissioning of a New Cryogenic Facility for Complex Superconducting Thin Film Testing

SRF, experiment, site, cavity

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.

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THPAL116

Development and Installation of the CANREB RFQ Buncher at TRIUMF

rfq, bunching, TRIUMF, emittance

3914

B. Barquest, F. Ames, T. Au, L. Graham, M.R. Pearson, V. Zvyagintsev
TRIUMF, Vancouver, Canada
J. Bale, J. Dilling, R. Kruecken, Y. Lan
UBC & TRIUMF, Vancouver, British Columbia, Canada
G. Gwinner
University of Manitoba, Manitoba, Canada
N. Janzen, R.A. Simpson
UW/Physics, Waterloo, Ontario, Canada
R. Kanungo
Saint Mary's University, Halifax, Canada

Funding: TRIUMF receives federal funding via the National Research Council of Canada. CANREB is funded by the Canada Foundation for Innovation (CFI), the Provinces NS, MB and TRIUMF.
Pure, intense rare isotope beams at a wide range of energies are crucial to the nuclear science programs at TRIUMF. The CANREB project will deliver a high resolution spectrometer (HRS) for beam purification, and a charge breeding system consisting of a radiofrequency quadrupole (RFQ) beam cooler and buncher, an electron beam ion source (EBIS), and a Nier-type spectrometer to prepare the beam for post-acceleration. Bunching the beam prior to charge breeding will significantly enhance the efficiency of the EBIS. The RFQ buncher will accept continuous §I{60}{keV} rare isotope beams from the ARIEL or ISAC production targets and efficiently deliver low emittance bunched beams. A pulsed drift tube (PDT) will adjust the energy of the bunched beam for injection into the EBIS to match the acceptance of the post-accelerating RFQ. Ion optical simulations were carried out to inform the design of the RFQ buncher and PDT. Simulations indicate that delivery of up to 10⁷~ions per bunch with high efficiency is possible. Experience with previous beam bunchers was also brought to bear in the design effort. Installation of the RFQ is under way, and tests with offline beam are expected to be performed in late 2018.

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THPAL120

Cryogenics Infrastructure at TRIUMF's Particle Accelerator Facilities

cryogenics, TRIUMF, ISAC, SRF

3925

A.N. Koveshnikov, Y. Bylinskii, G.W. Hodgson, D. Kishi, R.E. Laxdal, R.R. Nagimov, D. Yosifov
TRIUMF, Vancouver, Canada

Funding: TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada.
Cryogenic infrastructure is an indispensable part of TRIUMF accelerator facilities. At the moment TRIUMF operates three helium cryogenic systems supporting operation of three major accelerator systems: 520 MeV proton cyclotron, superconductive radio-frequency (SRF) heavy ion linear accelerator at the Rare Isotope Beams (RIB) facility, and SRF electron linear accelerator (e-linac) at Advanced Rare IsotopE Laboratory (ARIEL). Applications of cryogenic thermal loads vary from cryogenic absorption pumping of the cyclotron vacuum tank to cryogenic cooling of superconducting (SC) RF cavities of production accelerators and support of research and development at SRF department. Wide range of production techniques for cryogenic refrigeration includes helium refrigerators based on both piston and turbine expansion coldboxes for both 4 K and 2 K temperature cryogenic loads. This paper presents the details of TRIUMF cryogenic systems as well as operational experience of various cryogenic installations.

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THPAL121

The Operational Experience of E-Linac Cryogenic System at TRIUMF

cryogenics, cryomodule, MMI, linac

3928

R.R. Nagimov, Y. Bylinskii, D. Kishi, S.R. Koscielniak, A.N. Koveshnikov, R.E. Laxdal, D. Yosifov
TRIUMF, Vancouver, Canada

Funding: ARIEL is funded by CFI, the Provinces of AB, BC, MA, ON, QC, and TRIUMF. TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada.
The new Advanced Rare IsotopE Laboratory (ARIEL) is a major expansion of the Rare Isotope Beams (RIB) facility at TRIUMF. Superconducting radio-frequency (SRF) cavities cooled down to 2 K are the key part of ARIEL electron linear accelerator (e-linac). Design of the cryogenic system was bound to follow both phased project schedule and existing building infrastructure. Due to the scheduling of commissioning and R&D activities of ARIEL project, high availability requirements were set for e-linac cryogenic system during its commissioning stage. Various upgrades were introduced during system commissioning in order to improve overall availability and reliability of the system. This paper presents the details of operational experience, commissioning activities and continuous improvement of various operational aspects of e-linac cryogenic system.

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THPAL134

Commissioning of the Prototype C75 Cavities in a CEBAF Cryomodule

cavity, cryomodule, MMI, HOM

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.

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THPAL137

Acceptance Testing of the First Group of LCLS II Cryomodules at Jefferson Lab

cavity, cryomodule, 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.

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THPAL151

Progress in Understanding Breakdown Characteristics of X-Band Choke-Mode Structures

timing, cavity, experiment, HOM

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.

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THPAL155

Fabrication and Cold Test of the Correction Cavity Chain for Klystron-Based CLIC

cavity, 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.

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THPMF007

Commissioning of the Hybrid Superconducting/Normal Conducting RF System in the Diamond Storage Ring

cavity, storage-ring, 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.

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THPMF010

Status of Elettra and Future Upgrades

dipole, lattice, emittance, status

4054

E. Karantzoulis, A. Carniel, R. De Monte, S. Krecic, C. P. Pasotti
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with the possible future upgrades especially concerning the next ultra low emittance light source Elettra 2.0

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THPMF014

First Experiments at the CLEAR User Facility

electron, experiment, radiation, plasma

4066

R. Corsini, A. Curcio, S. Curt, S. Döbert, W. Farabolini, D. Gamba, R. Garcia Alia, T. Lefèvre, G. McMonagle, P.K. Skowroński, M. Tali, F. Tecker
CERN, Geneva, Switzerland
E. Adli, C.A. Lindstrøm, K.N. Sjobak
University of Oslo, Oslo, Norway
R.M. Jones, A. Lagzda
UMAN, Manchester, United Kingdom

The new "CERN Linear Electron Accelerator for Research" (CLEAR) facility at CERN started its operation in fall 2017. CLEAR results from the conversion of the CALIFES beam line of the former CLIC Test Facility (CTF3) into a new testbed for general accelerator R&D and component studies for existing and possible future accelerator applications. CLEAR can provide a stable and reliable electron beam from 60 to 220 MeV in single or multi bunch configuration at 1.5 GHz. The experimental program includes studies for high gradient acceleration methods, e.g. for CLIC X-band and plasma technology, prototyping and validation of accelerator components, e.g. for the HL-LHC upgrade, and irradiation test capabilities for characterization of electronic components and for medical applications. An overview of the facility capabilities and a summary of the latest results will be presented.

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THPMF017

Operation Improvements and Emittance Reduction of the ESRF Booster

emittance, booster, quadrupole, SRF

4077

N. Carmignani, N. Benoist, J-F. B. Bouteille, M.G. Di Vito, F. Ewald, L. Farvacque, A. Franchi, O. Goudard, J.M. Koch, S. Lagarde, S.M. Liuzzo, B. Ogier, T.P. Perron, P. Raimondi, D. Robinson, F. Taoutaou, E.T. Taurel, P.V. Verdier, R. Versteegen, P. Vidal, S.M. White
ESRF, Grenoble, France

The ESRF storage ring will be replaced by the Extremely Brilliant Source (EBS) in 2020 and the equilibrium emittance will decrease from the present 4 nmrad to 134 pmrad. The current injector system, composed by a linac and a synchrotron booster, will be used to inject into the new storage ring. To increase the injection efficiency in the new storage ring, three methods to reduce the horizontal emittance of the booster have been considered and tested. This paper presents the studies and achievements in terms of operation improvements and emittance reduction.

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THPMF021

ESRF Operation Status

injection, SRF, power-supply, booster

4088

J.-L. Revol, J.C. Biasci, N. Carmignani, A. D'Elia, A. Franchi, L. Hardy, J. Jacob, I. Leconte, S.M. Liuzzo, H.P. Marques, T.P. Perron, E. Plouviez, P. Raimondi, B. Roche, K.B. Scheidt, L. Torino, S.M. White
ESRF, Grenoble, France

The European Synchrotron Radiation Facility (ESRF) is undergoing the second phase (2015-2022) of an Up-grade which concerns its infrastructure, beamlines and X-ray source. This paper reports on the present operational source performance, highlighting the most recent developments, and the preparation of the Extremely Brilliant Source project. The renovation of the injector and the recent operation in top-up mode are also detailed.

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THPMF031

In-Vacuum APPLE II Undulator

vacuum, undulator, cryogenics, FEL

4114

J. Bahrdt, W. Frentrup, S. Grimmer, C. Kuhn, C. Rethfeldt, M. Scheer, B. Schulz
HZB, Berlin, Germany

APPLE II undulators are widely used in many synchrotron radiation facilities for the generation of arbitrarily polarized light, because they provide the highest magnet fields among all planar variably polarizing permanent magnet undulators (PMUs). So far, in-vacuum permanent magnet undulators (IVUs) have a fixed polarization, either planar or elliptical / helical. A variably polarizing in-vacuum undulator was never built due to the engineering challenges. We present the design of a new in-vacuum APPLE II, which will extend the photon energy range to tender X-rays in the 1.7 GeV storage ring BESSY II.

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THPMF033

Design of the Beamline Elements in the BESSY VSR Cold String

cavity, synchrotron, HOM, shielding

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.

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THPMF038

Status of the BESSY VSR Project

cavity, vacuum, 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.

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THPMF041

Low Emittance Lattice for PF-AR

optics, emittance, injection, cavity

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.

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THPMF043

Development and Present Status of Photon Factory Light Sources

injection, septum, vacuum, storage-ring

4155

T. Honda, Y. Kobayashi, S. Nagahashi, R. Takai
KEK, Ibaraki, Japan

Photon Factory of KEK manages two light sources, Photon Factory storage ring (PF-ring) and Photon Factory Advanced Ring (PF-AR) with an energy of 2.5 GeV and 6.5 GeV, respectively. Although it is unfortunate that the operation time of the accelerators is decreasing recent years due to a budget shortage and some unavoidable reconstructions, we are continuing the operation with a low failure rate and constructing a new beamline based on a novel undulator. Preparing for the start of the physics run of Super KEKB Factory, a new full energy beam transport line from the injector LINAC to PF-AR was constructed. With an installation of pulsed quadrupole magnets for the LINAC, continuous top-up injection has been established simultaneously for the four storage rings of PF and Super KEKB, and the operation of them has become compatible. As a result of increasing the injection energy of PF-AR form 3 GeV to 6.5 GeV, the beam instability during the injection disappeared, and the stability and efficiency of the injection improved significantly.

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THPMF045

Synchronized Beam Position Measurement for SuperKEKB Injector Linac

linac, controls, electron, EPICS

4159

M. Satoh, F. Miyahara, T. Suwada
KEK, Ibaraki, Japan
T. Kudou, S. Kusano
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
T. Ohfusa, H.S. Saotome, M. Takagi
Kanto Information Service (KIS), Accelerator Group, Ibaraki, Japan

Toward SuperKEKB project, the injector linac upgrade is ongoing for aiming at the stable beam operation with low emittance and high intensity bunch charge. One of the key challenges is a low emittance preservation of electron beam because the vertical emittance of 20 mm.mrad or less should be transported to the main ring without a damping ring. For this purpose, the fine alignment of accelerator components is a crucial issue since the linac alignment was badly damaged by the big earthquake in 2011. From the simulation results of emittance growth, the alignment of the quadrupole magnets and accelerating structures should be conducted at the level of 300 um in rms along the 600-m-long linac. In addition, we are aiming at the level of 100 um alignment in rms within the short range distance of 100 m long. Even after the fine component alignment can be achieved, the fine beam orbit manipulation is necessary for low emittance preservation. For these reasons, we have developed the new BPM readout system based on VME64x. The new system has improved the precision of beam position measurement up to 3 um from 25 um. We will describe the software development of the new BPM readout system.

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THPMF062

Smith-Purcell Radiation for Bunch Length Measurements at the Injection of MESA

radiation, detector, electron, cavity

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.

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THPMF063

The MESA 15 kW cw 1.3 GHz Solid State Power Amplifier Prototype

experiment, SRF, linac, cavity

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.

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THPMF066

Performance of a Full Scale Superconducting Undulator with 20 mm Period Length at the KIT Synchrotron

undulator, synchrotron, storage-ring, electron

4223

S. Casalbuoni, S. Bauer, E. Blomley, N. Glamann, A.W. Grau, T. Holubek, E. Huttel, D. Saez de Jauregui
KIT, Eggenstein-Leopoldshafen, Germany
C. Boffo, T.A. Gerhard, M. Turenne, W. Walter
Bilfinger Noell GmbH, Wuerzburg, Germany

Within the collaborative effort between KIT and Bilfinger Noell GmbH the development of a full scale superconducting undulator with 20 mm period length (SCU20) has been completed. This device addresses the reliability and reproducibility aspects of the manufacturing process, allowing for the status of a commercial product. The conduction cooled 1.5 m long coils were characterized in the KIT horizontal test facility CASPER II and later assembled in the final cryostat. The system was extensively tested in the final configuration before installation in the KIT storage ring KARA (Karlsruhe Research Accelerator) to be the source of the NANO beamline in December 2017. Here we present the performance of the device.

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THPMF070

Non-Linear Optics and Low Alpha Operation at the Storage Ring KARA at KIT

wiggler, octupole, resonance, injection

4235

A.I. Papash, E. Blomley, M. Brosi, J. Gethmann, B. Kehrer, A.-S. Müller, M. Schuh, P. Schönfeldt, J.L. Steinmann
KIT, Karlsruhe, Germany

The storage ring Karlsruhe Research Accelerator (KARA) at KIT operate in a wide energy range from 0.5 to 2.5 GeV. Different non-linear effects, in particular, residual octupole components of the magnetic field of the CATACT wiggler at high field level (2.5 T), proximity of the working point to a vertical sextupole resonance Qy=8/3 and weak coupling octupole resonance 2Qx+2Qy=19, high chromaticity, etc. decrease the beam life time. This is because of the reduced dynamic aperture and momentum acceptance for off-momentum particles. A new operation point at high vertical tune Qy=2.81 was tested. For this, injection and ramping tables have been modified. First the values were optimized by simulations, then during beam tests, to minimize betatron tune shaking during beam-energy ramps. It stabilized high-current beams by the fast-feedback system the whole process: injection at 0.5 GeV, ramping, and operation at 1.3 GeV cycles. It essentially improved life time and beam current. In addition, new low-alpha tables have been created and tested, resulting in the reduction of the momentum compaction factor to 10^-4. Short bunch operation at 0.5GeV injection energy was also tested successfully.

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THPMF088

R&D Activity on Alkali-Antimonied Photocathodes at INFN-Lasa

cathode, laser, gun, electron

4284

D. Sertore, P. Michelato, L. Monaco
INFN/LASA, Segrate (MI), Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

Based on the long-term experience on R&D and production of cesium telluride photocathodes for the high brightness photo-injectors and the past experience on green photocathodes developed in ‘90s , we have started a new R&D activity aiming to reach a reproducible and robust recipe for green photocathodes usable in RF gun. In this paper we present and discuss the first results so far obtained on K2CsSb photoemissive films deposited on polished Mo plugs and the plan for future studies.

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THPMF090

Linac Design Elements for Spaceborne Accelerators

cavity, linac, 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.

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THPMK014

Quantitative Analysis of Multipole Errors Induced by Mechanical Deformations of an Undulator

multipole, undulator, dipole, sextupole

4321

T.Y. Chung, C.H. Chang, C.-S. Hwang
NSRRC, Hsinchu, Taiwan
H.W. Luo
NTHU, Hsinchu, Taiwan

To minimize unwanted beam dynamics effects in a storage ring, multipole errors in an undulator are normally reduced by sorting and shimming methods. Nonetheless, an investigation of the error source is worth pursuing and interesting. Our work focuses on multipole errors introduced by mechanical deformations of an APPLE-II type undulator, which undergoes complicated forces during operation. Our results give guidelines for mechanical specifications derived from quantitative analyses.

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THPMK015

Low Momentum Compaction Lattice Operation of the Taiwan Photon Source

lattice, emittance, storage-ring, quadrupole

4325

C.-C. Kuo, C.H. Chen, J.Y. Chen, P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Huang, C.C. Liang, C.Y. Liao, Y.-C. Liu, Z.K. Liu, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

In order to provide short bunch length for picosecond time-resolved experiments and for coherent IR/THz radiation, low momentum compaction factor (alpha) lattices have been commissioned recently at the Taiwan Photon Source (TPS). The momentum compaction can be positive or negative and its value can be reduced by more than two orders of magnitude. In this paper, we discuss variable low alpha lattice optics, its beam dynamics issues, the measured momentum compaction and bunch lengths as well as beam orbit stability issues, etc.

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THPMK031

Elliptically Polarizing Undulator Design for PAL-XFEL

undulator, FEL, controls, electron

4362

S.J. Lee, J.H. Han, D.E. Kim
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2017R1C1B1012852).
Elliptically polarizing undulator (EPU) is under consideration as after-burner for the PAL-XFEL soft X-ray beamline to control the FEL polarization. In the soft X-ray line, seven planar undulators with a 35 mm period and 5 m length are in operation. To provide a polarization control of the FEL in the 1 to 3 nm wavelength, we compare the two types of EPUs, APPLE-II, and APPLE-X. The K value ranges for various operation modes are numerically studied for two undulator periods, 35 and 40 mm, of these EPU types.

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THPMK032

RADFET Installation at PAL-XFEL Undulator

undulator, radiation, FEL, controls

4366

J.H. Han, Y.G. Jung, D.E. Kim, S.J. Lee, G. Mun
PAL, Pohang, Kyungbuk, Republic of Korea

Two undulator beamlines, one hard X-ray and one soft X-ray, are in operation at PAL-XFEL. Radiation produced during the FEL operation may impair the magnetic property of the undulator magnets and affect the FEL performance. Accumulated radiation at the undulator sections is being measured by using optically stimulated luminescent dosimeters (OSLDs) once per few months. Over 10 Gy gamma ray was detected at some locations at both undulator beamlines. However, in the measurement using the OSLDs we do not have information on which accelerator operation modes produce such high level of radiation on the undulators. To measure accumulated radiation in real time, we installed radiation-sensing field-effect transistors (RADFETs). We report the characteristics of the RADFET sensors and the installation at the PAL-XFEL undulator beamlines.

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THPMK033

PAL-XFEL Linac RF System Status

klystron, controls, electron, FEL

4369

H.-S. Lee, Heo, J.Y. Heo, J.H. Hong, H.-S. Kang, K.H. Kim, S.H. Kim, D.H. Na, S.S. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: Ministry of Science and ICT
The PAL-XFEL Linear Accelerator began user support in March 2017 after one year of RF conditioning in 2016. The energy jitter was 0.013% when operating the H-X linear accelerator with 46 modulators, Klystron, LLRF, SSA and vacuum system at 6.838 GeV energy during user support period. So far, we have replaced four klystrons and 10 thyratron switches. We also measured the influence of temperature changes of RF components according to repetition rates of the machine. We will report on the measurement results of this operating experience and performance.

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THPMK048

The Design and Construction of a Novel Dual-Mode Dual-Frequency Linac Design

impedance, cavity, 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.

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THPMK063

Photocathode Preparation and Characteristics of the Electron Source for the VELA/CLARA Facility

cathode, plasma, laser, electron

4442

T.C.Q. Noakes, D. Angal-Kalinin, L.S. Cowie, F. Jackson, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, M.D. Roper, E.W. Snedden, R. Valizadeh, D.A. Walsh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
D. Angal-Kalinin, L.S. Cowie, F. Jackson, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The VELA and CLARA front end accelerators at Daresbury are test facilities with a focus on FEL research and industrial applications of electron beams. Recently the CLARA injector has been commissioned with acceleration of beam to 50 MeV. For several years a normal conducting 2.5 cell S-band cavity RF gun operated at up to 80 MV/m has been used as the electron source for both VELA and CLARA. For further beam acceleration an S-band travelling wave 2m long cavity has been used. The gun has used several different copper cathodes throughout its operational life, employing different preparation techniques. Oxygen plasma treatment is a well-known procedure for removing hydrocarbon contamination from surfaces whereas Argon plasma treatment also removes contaminants and typically leaves a thinner oxide at the surface. In this study we compare dark current (from field emission), as measured directly after the gun, for these alternate surface preparations and also present results from post-use electron microscopy analysis of the photocathodes. Electromagnetic simulations are used to help explain the results.

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THPMK064

RF System for SXFEL: C-band, X-band and S-band

FEL, linac, klystron, LLRF

4446

W. Fang, Q. Gu, X.X. Huang, L. Li, Z.B. Li, J.H. Tan, C.C. Xiao, J.Q. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

Shanghai Soft X-ray FEL facility is under commissioning now, which linac is compased of one S-band injector, C-band main linac and X-band linearizer. In SXFEL S-band injector could provide 200MeV beam energy based on 4 RF power unit, and then 6 C-band RF units boost beam energy to 840MeV based on 33MV/m at least, which will be ramped to 40MV/m in the ungrading. In the middle of S-band and C-band RF system, a X-band RF unit is used as linearizer to make energy spread of electron beam linear distribution, which is important for bunch compressor and FEL radiation. In this paper, details of RF system design and status of SXFEL is introduced, and some operation results are presented.

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THPMK087

Conceptual Design of the RF System for the Storage Ring and Linac of the New Light Source in Thailand

cavity, storage-ring, linac, acceleration

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.

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THPMK092

SOLEIL Status Report

storage-ring, synchrotron, controls, undulator

4516

L.S. Nadolski, G. Abeillé, Y.-M. Abiven, P. Alexandre, F. Bouvet, F. Briquez, P. Brunelle, A. Buteau, N. Béchu, M.-E. Couprie, X. Delétoille, T. Didier, J.M. Dubuisson, C. Herbeaux, N. Hubert, C.A. Kitegi, M. Labat, J.-F. Lamarre, P. Lebasque, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, F. Marteau, A. Nadji, R. Nagaoka, P. Prigent, F. Ribeiro, K.T. Tavakoli, M.-A. Tordeux, M. Valléau
SOLEIL, Gif-sur-Yvette, France

SOLEIL is both a synchrotron light source and a research laboratory at the cutting edge of experimental techniques dedicated to matter analysis down to the atomic scale, as well as a service platform open to all scientific and industrial communities. This French 2.75 GeV third generation synchrotron light source provides today extremely stable photon beams to 29 beamlines (BLs) complementary to ESRF. We report facility performance, ongoing projects and recent major achievements. A significant work was performed in order to secure the operation of the two canted 5.5 mm in-vacuum cryogenic permanent magnet undulators (CPMUs). Major R&D areas will also be discussed, and progress towards a lattice baseline for making SOLEIL a diffraction limited storage ring.

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THPMK101

Inverted Geometry Photo-Electron Gun Research and Development at TU Darmstadt

cathode, gun, electron, linac

4545

M. Herbert, J. Enders, Y. Fritzsche, N. Kurichiyanil, V. Wende
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by the Deutsche Forschungsgemeinschaft through GRK 2128 'AccelencE'
The Institute for nuclear physics at TU Darmstadt houses the Superconducting Darmstadt Linear Accelerator S-DALINAC. A photo-electron gun using GaAs photocathodes to provide pulsed and/or polarized electron beams, the S-DALINAC Polarized Injector SPIn, has been installed * for future nuclear-structure investigations**. In order to conduct research and development for this source, a test facility for Photo-Cathode Activation, Test and Cleaning using atomic-Hydrogen (Photo-CATCH) has been constructed***. This setup provides several chambers for photocathode handling and a 60 keV beamline for photo-gun design studies****. Currently, an upgraded inverted insulator geometry is under investigation for Photo-CATCH that is supposed to be implemented at SPIn. We will present the current developments at Photo-CATCH and future measurements.
* Y. Poltoratska et al., J. Phys.: Conf. Series 298 (2011)
** J. Enders, AIP Conf. Proc. 1563, 223 (2013)
*** M. Espig, Diss., TU Darmstadt (2016)
**** N. Kurichiyanil, Diss., TU Darmstadt (2016)

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THPMK103

Initial Testing of Techniques for Large Scale Rf Conditioning for the Compact Linear Collider

linac, linear-collider, ECR, collider

4548

T.G. Lucas, M.J. Boland, P.J. Giansiracusa, R.P. Rassool, M. Volpi
The University of Melbourne, Melbourne, Victoria, Australia
N. Catalán Lasheras, A. Grudiev, T. Lefèvre, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch, V. del Pozo Romano
CERN, Geneva, Switzerland
J. Paszkiewicz
University of Oxford, Oxford, United Kingdom
C. Serpico
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Vnuchenko
IFIC, Valencia, Spain
R. Zennaro
PSI, Villigen PSI, Switzerland

Nominal operating conditions for the Compact Linear Collider (CLIC) 380 GeV requires 72 MV/m loaded accelerating gradients for a 180 ns flat-top pulse. Achieving this requires extensive RF conditioning which past tests have demonstrated can take several months per structure, when conditioned at the nominal repetition rate of 50 Hz. At CERN there are three individual X-band test stands currently operational, testing up to 6 structures concurrently. For CLIC's 380 GeV design, 28,000 accelerating structures will make up the main linac. For a large scale conditioning programme, it is important to understand the RF conditioning process and to optimise the time taken for conditioning. In this paper, we review recent X-band testing results from CERN's test stands. With these results we investigate how to optimise the conditioning process and demonstrate the feasibility of pre-conditioning the structures at a higher repetition rate before installation into the main linac.

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THPMK106

Architectural Considerations for Recirculated and Energy-Recovered Hard XFEL Drivers

FEL, linac, recirculation, SRF

4560

D. Douglas, S.V. Benson, T. Powers, Y. Roblin, T. Satogata, C. Tennant
JLab, Newport News, Virginia, USA
D. Angal-Kalinin, N. Thompson, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
T.K. Charles
CERN, Geneva, Switzerland
R.C. York
FRIB, East Lansing, Michigan, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A confluence of events motivates discussion of design options for hard XFEL driver accelerators. Firstly, multiple superconducting radio-frequency (SRF) driven systems are now online (European XFEL), in construction (LCLS-II), or in design (MARIE); these provide increasing evidence of the transformational potential they offer for fundamental science with its concomitant benefits. Secondly, operation of 12 GeV CEBAF* validates use of recirculation in high energy SRF linacs. Thirdly, advances in the analysis and control of effects such as coherent synchrotron radiation (CSR) and the microbunching instability (uBI) have been recently achieved. Collectively, these developments offer insights providing extended facility science reach, reduced costs, multiplicity (i.e., support of numerous FELs operating over a range of wavelengths), and enhanced scalability and upgradability (to higher powers and energies). We will discuss the relationship amongst the various threads, and indicate how they inform design choices for the system architecture of an option for the UK-XFEL** - that of a staged multi-user X-ray FEL and nuclear physics facility based on a multi-pass recirculating SRF CW linac.
*M. Spata, "12 GeV CEBAF Initial Operations and Challenges", these proceedings.
**P. Williams et al., Proc. FLS2018, Shanghai, China (March 2018).

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THPML017

Beam Dynamics Calculation of a New Injection System for LINAC II

gun, electron, linac, injection

4687

J.X. Zhang, M. Hüning
DESY, Hamburg, Germany

The Linac II at DESY (Deutsches Elektronen Synchrotron) is an electron/positron linear accelerator with a 400 MeV primary electron linac, an 800 MW positron converter, and a 450 MeV secondary electron/positron linac. For reliability two injection systems can be switched, a 150 kV bombarder diode gun dating from 1969 and a 100 kV triode gun commissioned in 2014. The older bombarder gun shall be replaced with a triode gun optimized for injection into the synchrotron radiation facility PETRA III. In this paper, the parameters of the existing injectors and the design considerations for the new injector are presented. The preliminary beam dynamics calculation of the new injection system will be performed; the future plan of the replacement will be discussed.

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THPML020

The First Results of Trial Operation and Performance Improve of the 100 MeV/ 100 kW Electron Linear Accelerator of the NSC KIPT SCA Neutron Source

electron, neutron, gun, MMI

4693

A.Y. Zelinsky, O.E. Andreev, V.P. Androsov, O. Bezditko, O.V. Bykhun, A.N. Gordienko, V.A. Grevtsev, A. Gvozd, V.E. Ivashchenko, I.I. Karnaukhov, I.M. Karnaukhov, V.P. Lyashchenko, M. Moisieienko, A.V. Reuzayev, D.V. Tarasov, V.I. Trotsenko
NSC/KIPT, Kharkov, Ukraine
Y.L. Chi
IHEP, Beijing, People's Republic of China

The NSC KIPT SCA Neutron Source uses 100 MeV/ 100 kW electron linear accelerator as a driver for the generation of the initial neutrons. The trial operation of the accelerator was started in 2018. To provide design electron beam parameters is the primary task of the first stage of the trial operation. During the first stage of the accelerator operation the following tasks were under consideration: minimization of the electron beam losses along accelerator, providing of the stable electron beam pulse current, adjustment of the electron beam position along accelerator and providing of the uniform electron beam distribution at the tungsten neutron generating target. The main results of the accelerator operation and methods of performance improve are described in the paper.

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THPML025

Operation of an RF Modulated Thermionic Electron Source at TRIUMF

electron, cathode, TRIUMF, emittance

4705

F. Ames, K. Fong, B. Humphries, S.R. Koscielniak, A. Laxdal, Y. Ma, T. Planche, S. Saminathan, E. Thoeng
TRIUMF, Vancouver, Canada

ARIEL (Advanced Rare IsotopE Laboratory) at TRIUMF will use a high-power electron beam to produce radioactive ion beams via photo-fission. The system has been designed to provide up to 10 mA of electrons at 30 MeV. The electron source delivers electron bunches with charge up to 16 pC at a repetition frequency of 650 MHz at 300 keV. The main components of the source are a gridded dispenser cathode (CPI - Y845) in an SF6 filled vessel and an in-air HV power supply. The beam is bunched by applying DC and RF fields to the grid. A macro pulse structure can be applied by additional low frequency modulation of the RF signal. This allows adjusting the average beam current by changing the duty factor of the macro pulsing. Unique features of the gun are its cathode/anode geometry to reduce field emission, and transmission of RF modulation via a dielectric (ceramic) waveguide through the SF6. The source has been installed and fully commissioned to a beam power up to 1 KW and tests with accelerated beams have been performed. Measurements of the beam properties and results from the commissioning and operational experiences of the source will be presented.

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THPML044

Operation of a Cryogenic Current Comparator with Nanoampere Resolution for Continuous Beam Intensity Measurements in the Antiproton Decelerator at CERN

cryogenics, proton, antiproton, injection

4741

M.F. Fernandes, D. Alves, T. Koettig, A. Lees, J. Tan
CERN, Geneva, Switzerland
M.F. Fernandes, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
M. Schwickert, T. Stöhlker
GSI, Darmstadt, Germany
T. Stöhlker
IOQ, Jena, Germany
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This project has received funding from the European Union's Seventh Framework Programme, under grant agreement number 289485.
Low-intensity charged particle beams are particularly challenging for non-perturbative beam diagnostics due to the small amplitude of induced electromagnetic fields. The Antiproton Decelerator (AD) and Extra Low ENergy Antiproton (ELENA) rings at CERN decelerate beams containing 10⁷ antiprotons. An absolute intensity measurement of the circulating beam is essential to monitor the operational efficiency and to provide important calibration data for the antimatter experiments. This paper reviews the design of an operational Cryogenic Current Comparator (CCC) based on Superconducting QUantum Interference Device (SQUID) for current and intensity monitoring in the AD. Such a system has been operational throughout 2017, relying on a stand-alone cryogenic infrastructure based on a pulse-tube cryocooler. System performance is presented and correlated with different working environments, confirming a resolution in the nanoampere range.

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THPML054

Design Studies of an S-Band Multipacting Electron Gun

electron, cavity, gun, cathode

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.

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THPML066

Filling Pattern Measurement System Upgrade in SSRF*

storage-ring, SRF, synchrotron, injection

4791

N. Zhang, F.Z. Chen, Y.M. Zhou
SSRF, Shanghai, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China (No.11575282 No.11375255 No.11305253)
Filling pattern affects various operation performance of a synchrotron light source. A new diagnostic beam charge monitor (BCM) with high bandwidth multi-channels digitizer was developed to perform bunch-by-bunch charge measurement and record filling pattern for SSRF storage ring. Signals picked up from button elec-trodes were sampled synchronously with RF frequency, and IQ (In-phase and Quadrature phase) sampling meth-od was employed for noise-filtering and phase independ-ence calibration. Layout and evaluation experiment of the system are presented in this paper.

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THPML078

Web-Based Control Room Applications at TRIUMF

controls, TRIUMF, interface, multipole

4832

C.B. Barquest, P. M. Jung, S. Kiy, K.E. Lucow, T. Planche, S.D. Rädel, B.E. Schultz, D. Sehayek, O. Shelbaya, D. Tattan
TRIUMF, Vancouver, Canada
M. Corwin, S. Marcano
UW/Physics, Waterloo, Ontario, Canada

Control room applications are programs that interface with control systems and beam physics models. These tools range from real-time diagnostic visualizations to post-processing data analysis. At TRIUMF, the concept of web-based control room applications has been adopted to advance the capabilities of these applications and facilitate operations. This online model takes advantage of server-based continuous integration and a centralized middleware layer. Continuous integration of server-based applications allows for easy deployment and maintenance. A centralized middleware layer allows a single application to work for many different accelerator configurations. Some motivating examples of web-based applications currenly being developed are presented, demonstrating this online approach to be an effective method for deploying applications for use in the control room and beyond.

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THPML087

First ERL Operation of S-DALINAC and Commissioning of a Path Length Adjustment System

linac, recirculation, MMI, lattice

4859

M. Arnold, C. Burandt, R. Grewe, J. Pforr, N. Pietralla, M. Steinhorst
TU Darmstadt, Darmstadt, Germany
C. Eschelbach, M. Lösler
Frankfurt University of Applied Sciences, Frankfurt am Main, Germany
F. Hug
KPH, Mainz, Germany

Funding: Work supported by DFG through GRK 2128 and INST163/383-1/FUGG
The S-DALINAC is running in recirculating operation since 1991. In 2015/2016 a major upgrade was performed by adding a third recirculation beam line. The versatility of this recirculation beam line enables a phase shift of the beam of up to 360° of the RF phase. The required range of 10 cm for a 3 GHz RF frequency is realized by a path length adjustment system. A complementary operation in normal scheme (single-pass, once or thrice recirculating with acceleration) or ERL mode (once or twice) is possible by appropriate adjustment of this system. After installation this system was aligned properly and its functionality and stroke was checked without beam. The system was commissioned by measuring the change of the beam phase in dependency of the setting of the path length adjustment system. The complementary usage of the newly installed recirculation for once recirculating with acceleration and once recirculating with ERL mode has been shown successfully in autumn 2017. This contribution will provide an overview on the path length adjustment system and the first run of the once recirculating ERL mode of the S-DALINAC.

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THPML089

Tuning of 3-tap Bandpass Filter During Acceleration for Longitudinal Beam Stabilization at FAIR

emittance, feedback, controls, synchrotron

4866

B.R. Reichardt, 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

During acceleration in the heavy-ion synchrotrons SIS18/SIS100 at GSI/FAIR longitudinal beam oscillations are expected to occur. To reduce longitudinal emittance blow-up, dedi- cated LLRF beam feedback systems are planned. To date, damping of longitudinal beam oscillations has been demon- strated in SIS18 machine experiments with a 3-tap filter controller (e.g. *), which is robust in regard to control pa- rameters and also to noise. On acceleration ramps the control parameters have to be adjusted to the varying synchrotron frequency. Previous results from beam experiments at GSI indicate that a proportional tuning rule for one parameter and an inversely proportional tuning rule for a second parameter is feasible, but the obtained damping rate may not be opti- mal for all synchrotron frequencies during the ramp. In this work, macro-particle simulations are performed to evaluate, whether it is sufficient to adjust the control parameters pro- portionally (inversely proportionally) to the change in the linear synchrotron frequency, or if it is necessary to take more pa- rameters, such as bunch-length and synchronous phase, into account to achieve stability and a considerable high damping rate for excited longitudinal dipole beam oscillations. This is done for single- and dual-harmonic acceleration ramps.
* H. Klingbeil et al., "A Digital Beam-Phase Control System for Heavy-Ion Synchrotrons", in IEEE Transactions on Nuclear Science, vol. 54, no. 6, pp. 2604-2610, Dec. 2007.

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THPML102

Field and Cost Optimization of a 5 T/m Normal Conducting Quadrupole for the 10-MeV Beam Line of the eLINAC of the Mexican Particle Accelerator Community

quadrupole, power-supply, multipole, linac

4905

D. Chavez Valenzuela, G.H.I. Maury Cuna, M. Napsuciale Mendivil
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
J. C. Basilio Ortiz
CINVESTAV, Mexico City, Mexico
P.M. McIntyre, A. Sattarov
Texas A&M University, College Station, USA
C.A. Valerio
ECFM-UAS, Culiacan, Sinaloa, Mexico
B. Yee-Rendón
KEK, Ibaraki, Japan

The Mexican Particle Accelerator Community is currently designing the first Mexican RF eLINAC that will have three beamlines at 10, 60 and 100 MeV. In this work, we present an optimized design in terms of field quality and production cost for the 5 T/m normal conducting quadrupoles of the 10-MeV beamline. Several candidate materials for the yoke were studied based on their availability and machinability, with the aim to optimize in-house production cost (Mexico) while restricting a low multipole content.

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THPML124

Design of Beam Position Fast-Correction Magnet Power Supply for HALS

controls, power-supply, feedback, storage-ring

4967

Z.X. Shao, H. Gao, L. Wang, H.Y. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by 'Hefei Advanced Light Source Pre-research Project'
Hefei Advanced Light Source (HALS) is the fourth-generation radiation light source that is being pre-researched in China. Ultra-low emittance of the beam requires higher performance of power supply system. We designed a fast correcting power supply for the beam measurement needs. We adopted the all-digital method, the current closed-loop feedback used the AD7766 with 24-bit resolution as its A/D converter. And we added the corresponding constant temperature control, chain protection, etc. The small-signal frequency response of this system can reach more than 5kHz. The detail design scheme is described in this paper.

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THPML140

Radiation Monitoring System of HLSII

radiation, monitoring, detector, storage-ring

5011

Lin, H.S. Lin, Y.Q. Cai, S.P. Jiang, Z.B. Sun, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by the National Science Foundation of China 11675170 By the Fundamental Research Funds for the Central Universities WK2310000056
Monitoring of ionizing radiation of synchrotron radiation facility is very important for the safety of staff and users of the light source. Radiation monitoring system of HLSII has been built and the whole system consists of local radiation monitoring spots and central control system, and a web-based monitoring dynamic release system. The local radiation monitoring spot consists of a high air pressure ionization type gamma detector and a BF3 counting tube neutron detector, and the radiation data are calculated by microcontroller locally and acquired by the data server for further processing. The dynamic release system is integrated with EPICS interface and radiation safety interlock system. Other accelerator systems could obtain radiation data from the server and the interlock system is triggered by the radiation data to shut down the machine in case the radiation exceeds the safety threshold.

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FRXGBD1

Reliability and Availability of Particle Accelerators: Concepts, Lessons, Strategy

luminosity, collider, beam-losses, kicker

5014

A. Apollonio, L. Ponce, O. Rey Orozko, R. Schmidt, A.P. Siemko, B. Todd, J.A. Uythoven, A.P. Verweij, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland

This paper will present the results and latest status of an extensive effort to analyse and improve the reliability and availability of the LHC. After the introduction of basic concepts and definitions, the paper reviews the performance of the LHC in 2015-2017. A direct comparison of the luminosity production years 2016 and 2017 is presented, with a focus on the main differences in the observed failure modes. Based on the lessons learnt in this time window, expectations for the performance during future LHC runs are discussed. In particular, the thought process for the evaluation of the possible full energy exploitation of the LHC is described, considering relevant factors such as the expected availability loss and the risk associated to magnet training.

Slides FRXGBD1 [7.090 MB]

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FRXGBD3

Application of Carbon Nanotube Wire for Beam Profile Measurement of Negative Hydrogen Ion Beam

electron, rfq, linac, beam-loading

5022

A. Miura, K. Moriya
JAEA/J-PARC, Tokai-mura, Japan
T. Miyao
KEK, Ibaraki, Japan

A wire scanner monitor using metallic wire is reliably employed for the beam profile measurement in the J-PARC linac. Because the loading of negative hydrogen (H⁻) ion beam on a wire increases under high-current beam operation, we focus on using a high-durability beam profile monitors by attaching another wire material. Carbon nanotubes (CNT) are made of graphite in a cylindrical shape and have a tensile strength not less than 100 times that of steel. The electric conductivity has higher than that of metals, and hardness is endured thermally around 3000°C in a vacuum circumstance. We applied the CNT wires to WSM and measured transverse profiles with a 3-MeV and 191-MeV H⁻ beam. As a result, we obtained the equivalent signal levels taken by carbon wire made of polyacrylonitrile without any damage. In this paper, the signal response when the CNT is irradiated with an H⁻ beam and the result of beam profile measurement. In addition, the surface of CNT after 3-MeV beam operation was observed.

Slides FRXGBD3 [2.558 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-FRXGBD3

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