IPAC2018 - List of Keywords (vacuum)

Paper	Title	Other Keywords	Page
MOZGBE3	Primary Study of High-Power Graphene Beam Window	Windows, proton, target, scattering	47
	H. Wang, C. Meng, H. Qu, D.H. Zhu IHEP, Beijing, People's Republic of China X. Sun, P.C. Wang DNSC, Dongguan, People's Republic of China
	Beam windows are usually used to isolate vacuum or other special environments, which is a key device for high-power accelerators. Graphene has extremely high thermal conductivity, high strength and high transparency to high energy ions. It is highly suitable for beam windows if the technology is allowable. This paper will discuss the primary tests of graphene films, including vacuum per-formance and thermal conductivity performance, as well as the simulated performance of an assumed graphene window.
	Slides MOZGBE3 [1.751 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE3
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOZGBE4	Overview of Fabrication Techniques and Lessons Learned with Accelerator Vacuum Windows	Windows, target, operation, 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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOZGBE5	Results on the FCC-hh Beam Screen at the KIT Electron Storage Ring KARA	photon, electron, experiment, radiation	55
	L.A. Gonzalez, V. Baglin, P. Chiggiato, C. Garion, M. Gil Costa, R. Kersevan CERN, Geneva, Switzerland I. Bellafont, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain S. Casalbuoni, E. Huttel KIT, Eggenstein-Leopoldshafen, Germany
	Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union's Horizon 2020 research and innovation programme under grant No 654305. In the framework of the EuroCirCol collaboration* (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of 3 FCC-hh beam-screen (BS) prototypes has been carried out with the aim of testing them at room temperature at the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator). The 3 BS prototypes will be tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power, match the one foreseen for the 50+50 TeV FCC-hh proton collider. Each of the 3 BS prototypes, 2 m in length, implement a different design feature: 1) baseline design (BD), with electro-deposited copper and no electron-cloud (EC) mitigation features; 2) BD with set of distributed cold-sprayed anti-EC clearing electrodes; 3) BD with laser-ablated anti-EC surface texturing. We present here the results obtained so far at BESTEX and the comparison with extensive montecarlo simulations of the expected outgassing behavior under synchrotron radiation. The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information.
	Slides MOZGBE5 [4.318 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE5
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF031	Modelling Wake Impedance of a Rough Surface in Application to the FCC-hh Beamscreen	impedance, coupling, electron, laser	157
	S. Arsenyev, D. Schulte CERN, Geneva, Switzerland
	The inner surface of the future circular collider (FCC-hh) beamscreen is proposed to be laser-treated in order to mitigate the electron cloud build-up. However, the rough structure of the treated surface can result in unwanted impedance increase, potentially leading to the transverse mode coupling instability (TMCI). Three models have been adopted to estimate the wake impedance of a beamscreen with a rough surface. The models use the resistive wall formalism generalized for the case of an arbitrary surface impedance. The results apply to a beamscreen of a circular cross-section with the homogeneously rough inner surface for the case of ultrarelativistic particles. The free parameters of the models were fit into preliminary measurements of the surface resistivity, giving, as a result, a range of the real and the imaginary parts of the wake impedance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF031
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF053	Observations, Analysis and Mitigation of Recurrent LHC Beam Dumps Caused by Fast Losses in Arc Half-Cell 16L2	MMI, operation, electron, 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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF070	High Voltage Design for the Electrostatic Septum for the Mu2e Beam Resonant Extraction	cathode, high-voltage, simulation, extraction	289
	M.L. Alvarez, C.C. Jensen, D.K. Morris, V.P. Nagaslaev, H. Pham, D.G. Tinsley Fermilab, Batavia, Illinois, USA
	Two electrostatic septa (ESS) are being designed for the slow extraction of 8GeV proton beam for the Mu2e experiment at Fermilab. Special attention is given to the high voltage components that affect the performance of the septa. The components under consideration are the high voltage (HV) feedthrough, cathode standoff (CS), and clearing electrode ceramic standoffs (CECS). Previous experience with similar HV systems at Fermilab was used to define the evaluation criteria of the design of the high voltage components. Using electric field simulation software, high E-field intensities on the components and integrated field strength along the surface of the dielectric material were minimized. Here we discuss the limitations found and improvements made based on those studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF070
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMF085	Beam-gas Background Characterization in the FCC-ee IR	simulation, scattering, background, optics	322
	M. Boscolo, O.R. Blanco-García INFN/LNF, Frascati (Roma), Italy H. Burkhardt, R. Kersevan, M. Lueckhof CERN, Geneva, Switzerland F. Collamati INFN-Roma1, Rome, Italy
	The MDISim toolkit is used to evaluate and characterize the beam-gas induced background in the FCC-ee Interaction Region. MDISim allows a full characterization of this beam background source with the locations where the beam-gas scattering occurs as well as the loss points, as a function of different vacuum conditions and composition, for the nominal optics and parameters. Detailed pressure distribution profiles have been obtained running coupled synchrotron radiation and molecular flow montecarlo codes, as an input to the GEANT4 calculations. The particles hitting the pipe in the IR can be tracked in the detectors with a full Geant-4 simulation. Semi-analytic estimates for the expected rates and lifetime are also performed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF085
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPMK012	Electron Cloud Studies in FCC-ee	electron, collider, simulation, quadrupole	374
	E. Belli Sapienza University of Rome, Rome, Italy P. Costa Pinto, G. Rumolo, T.F. Sinkovits, M. Taborelli CERN, Geneva, Switzerland M. Migliorati INFN-Roma1, Rome, Italy
	Electron cloud effects are one of the most critical aspects for the LHC and the future circular colliders. In the frame of the electron-positron collider FCC-ee, an estimation of the electron cloud build up in the machine will be discussed in this paper. A preliminary evaluation of the heat load in the arc components and interaction region magnets will be presented, together with possible mitigation strategies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML011	Liquid Cluster Ion Beam Processing of Transition Metal Films	acceleration, radiation, target, experiment	415
	D. Shimizu, H. Ryuto, M. Takeuchi, D. Yamamoto Kyoto University, Photonics and Electronics Science and Engineering Center, Kyoto, Japan
	The irradiation effects of cluster ion beams are characterized by the high-density collision of molecules that comprise the clusters against a target. According to molecular dynamics calculations, the local temperature of the colliding cluster and the surface of the target are expected to increase to several thousand K. The enhancement of the chemical interactions between the molecules in the colliding clusters and the atoms on the target surface is expected, if polyatomic molecules, such as ethanol and acetone, are used for the source material of the cluster. So, the irradiation effects of the polyatomic liquid cluster ion beams on transition metal films have been studied to examine the possibility of utilizing the liquid cluster ion beam technique for the processing of transition metal films. The transition metal films were formed by magnetron sputtering. The liquid clusters were produced by the adiabatic expansion method and ionized by electron ionization. The sputtering yields of transition metal films induced by liquid cluster ions are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML011
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML029	A Portable X-ray Source Based on Dielectric Accelerators	electron, target, shielding, solenoid	464
	C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA S.P. Antipov, A. Kanareykin, R.A. Kostin Euclid Beamlabs LLC, Bolingbrook, USA
	Funding: The work has been supported by the U.S. Department of Homeland Security (DHS), Domestic Nuclear Detection Office (DNDO), under a competitively awarded contract No. HSHQDC-17-C-00007. The portable low energy accelerator based X-ray sources have attractive applications in the non-destructive examination as a replacement of radiological gamma isotope sources. We are developing an inexpensive ultra-compact dielectric accelerator technology for low energy electron beams. The portability in the realm of this proposal is unprecedented ~ 1 ft3 volume with ~ 50 lbs of weight. The use of ceramics makes the transverse size of the accelerating waveguide comparable to that of a pencil. Because of this size reduction, additional weight reduction of shielding becomes possible. The article will report on the progress of this project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML029
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML062	Accelerator Neutron Source for Boron Neutron Capture Therapy	neutron, proton, experiment, tandem-accelerator	550
	S.Yu. Taskaev, D.A. Kasatov, A.N. Makarov, Y.M. Ostreinov, I.M. Shchudlo, I.N. Sorokin BINP SB RAS, Novosibirsk, Russia T.A. Bykov Budker INP & NSU, Novosibirsk, Russia Ya.A. Kolesnikov, A.M. Koshkarev, E.O. Sokolova NSU, Novosibirsk, Russia
	Funding: This study was carried out with a grant from the Russian Science Foundation (project No. 14-32-00006-P) with the support of the Budker Institute of Nuclear Physics and Novosibirsk State University. A source of epithermal neutrons based on a vacuum-insulated tandem accelerator and a lithium target is developed for the technique of boron neutron capture therapy. A stationary proton beam of 2 MeV with a current of up to 5 mA was obtained in the accelerator. Neutron generation was performed and the flux and neutron spectrum were experimentally measured. A Beam Shaping Assembly was developed and manufactured, which makes it possible to form a therapeutic beam of neutrons to the greatest extent satisfying the requirements of BNCT. It was established that neutron irradiation of tumor cells of human glioma U251 and human glioblastoma T98G, previously incubated in a medium with boron, led to a significant suppression of their viability. Irradiation of mice with grafted human glioblastoma tumor led to their complete cure. In order to increase the beam parameters, the facility was equipped with a wire scanner OWS-30 (D-Pace, Canada; under the license of TRIUMF), a non-contact current sensor NPTC (Bergos, France), a FLIR T650SC infrared camera, an Optris CT Laser 3ML SF pyrometer (Optris, GmbH, Germany), cooled diaphragms with thermistors, telescopic beam receivers with thermoresistors, a new bushing insulator. Two new sources of negative hydrogen ions with a high current are being prepared, one of them is surface-plasma, the other is voluminous. The investigations established the effect of space charge and spherical aberration of lens on the ion beam transport, the dependence of the heating of the diaphragms of the electrodes and the size of the proton beam on the current of the injected beam of negative hydrogen ions and the pressure of the residual gas in the transport channel. The report describes the modernization of the accelerator, discusses the results of research, declares plans.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML062
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPML066	Ultrafast Mega-electron-volt Gas-Phase Electron Diffraction at SLAC National Accelerator Laboratory	electron, gun, laser, experiment	556
	X. Shen, R.K. Li, X.J. Wang, S.P. Weathersby, J. Yang SLAC, Menlo Park, California, USA
	Funding: This work was supported in part by the U.S. Department of Energy Contract No. DE-AC02-76SF00515, and the SLAC UED/UEM Initiative Program Development Fund. Ultrashort mega-electron-volt (MeV) electron beams from radio-frequency (rf) photoinjectors have recently attracted strong interests for application in ultrafast gas-phase electron diffraction (UGED). Such high-brightness electron beams are capable of providing 100-fs level temporal resolution and sub-Angstrom level spatial resolution to capture the ultrafast structural dynamics from photoexcited gas molecules. To experimentally demonstrate such an ultrafast electron scattering instrument, a high performance UGED system has been commissioned at SLAC National Accelerator Laboratory. The UGED instrument produces 3.7 MeV electron beams with 2 fC beam charge at 180-Hz repetition rate. The temporal resolution is characterized to be 150 fs full-width-at-half-maximum (FWHM), while the spatial resolution is measured to be 0.76 Å FWHM. The UGED instrument also demonstrates outstanding performance in vacuum, rf, and electron beam pointing stability. Details of the performance of the SLAC MeV UGED system is reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML066
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUYGBD2	A Review of DAΦNE Performances During the KLOE-2 Run	luminosity, detector, operation, 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
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

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

TUPAF021	Identification and Removal of SPS Aperture Limitations	optics, target, proton, injection	709
	V. Kain, R. Alemany-Fernández, H. Bartosik, S. Cettour Cave, K. Cornelis, P. Cruikshank, J.A. Ferreira Somoza, B. Goddard, C. Pasquino CERN, Geneva, Switzerland
	The CERN SPS (Super Proton Synchrotron) serves as LHC injector and provides beam for the North Area fixed target experiments. Since the 2016 run automated local aperture scans have been performed with the main focus on the vertical plane where limitations typically arise due to the flat vacuum chambers in most SPS elements. For LHC beams the aperture limitations with the present low integer tune optics also occur at locations with large dispersion. Aperture measurements in the horizontal plane using a variety of techniques were performed and showed surprising results, which could partially explain the unexpected losses of high intensity LHC beams at the SPS flat bottom. In this paper, reference measurements from 2016 are compared with the ones taken at the beginning of the run in 2017. Several aperture restrictions in the vertical plane could be found and cured, and a potential systematic restriction in the horizontal plane has been identified. The results of the measurements and the origin of the restrictions are presented in this paper, and the outlook for partial mitigation is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF030	Electron Cloud Build Up for LHC Sawtooth Vacuum Chamber	electron, photon, simulation, synchrotron	744
	G. Guillermo Cantón, F. Zimmermann CERN, Geneva, Switzerland G.H.I. Maury Cuna, E. D. Ocampo Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
	At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. For the arcs of LHC a sawtooth pattern had been imprinted on the horizontally outward side of the vacuum chamber in order to locally absorb synchrotron radiation photons without dispersing them all around the chamber. Using the combination of the codes Synrad3D and PyCLOUD we examine the effect of realistic absorption distributions with and without sawtooth on the build up of electron clouds.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF030
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF037	Validation of the CERN PS Eddy Current Injection Septa	septum, simulation, injection, HOM	768
	M. Hourican, B. Balhan, J.C.C.M. Borburgh, T. Masson, A. Sanz Ull CERN, Geneva, Switzerland
	As part of the upgrade of the CERN PS accelerator from 1.4 GeV to 2 GeV, new injection septa have been developed. The system is comprised of a pulsed eddy current septum magnet and a pulsed eddy current bumper magnet. Both magnets will be housed in a common vacuum vessel and powered by independent power converters. In-depth studies and simulations have been performed to reduce as much as possible the leak field by designing specific magnetic shielding, combined with dual function beam impedance shielding. A prototype magnet was built and measured to validate the simulations. The final complete system will be bake-able at 200C and uses demineralised water for cooling. Closed circuit cooling systems have been integrated to reduce risks of vacuum leaks. This report describes the electromechanical design from the concept and simulation stages to the prototyping and final manufacturing. Results of the initial magnetic measurements, including field homogeneity and leak field mitigation methods are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF037
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF049	Analysis of Loss Signatures of Unidentified Falling Objects in the LHC	proton, operation, beam-losses, 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).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF049
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

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

TUPAF076	Design of PIP-II Medium Energy Beam Transport	SRF, linac, kicker, cryomodule	905
	A. Saini, C.M. Baffes, A.Z. Chen, V.A. Lebedev, L.R. Prost, A.V. Shemyakin Fermilab, Batavia, Illinois, USA
	Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics The Proton Improvement Plan-II (PIP-II) is a proposed upgrade for the accelerator complex at Fermilab. The central piece of PIP-II is a superconducting radio frequency (SRF) 800 MeV linac capable of operating in both CW and pulse regimes. The PIP-II linac comprises a warm front-end that includes a H⁻ ion source capable of delivering 15-mA, 30-keV DC or pulsed beam, a Low Energy Beam Transport (LEBT), a 162.5 MHz, CW Radio-Frequency Quadrupole (RFQ) accelerating the ions to 2.1 MeV and, a 14-m Medium Energy Beam Transport (MEBT) before beam is injected into SRF part of the linac. This paper presents the PIP-II MEBT design and, discusses operational features and considerations that lead to existing optics design such as bunch by bunch chopping system, minimization of radiation coming to the warm front-end from the SRF linac using a concrete wall, a robust vacuum protection system etc.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF076
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAF084	The First-of-Series SIS100 Cryocatcher	cryogenics, site, HOM, instrumentation	930
	L.H.J. Bozyk, Sh. Ahmed, P.J. Spiller GSI, Darmstadt, Germany
	The superconducting heavy ion synchrotron SIS100 of the FAIR-facility will be equipped with 60 cryocatcher, to suppress dynamic vacuum effects. A prototype cryocatcher has been designed, manufactured and underwent several tests. The results yielded in the design of the series cryocatcher. Recently, the First-of-Series cryocatcher has been manufactured and tested. Results from the manufacturing process and the site acceptance tests, including cryogenic test with liquid helium are presented. The FoS cryocatcher sucessfully passed all tests and the series production will be released.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF084
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

TUPAL046	Construction, Test, and Operation of a new RFQ at the Spallation Neutron Source (SNS)	rfq, operation, linac, ion-source	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL046
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL055	Progress with Carbon Stripping Foils at ISIS	operation, synchrotron, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL055
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAL056	High Order Image Terms and Harmonic Closed Orbits at the ISIS Synchrotron	closed-orbit, simulation, resonance, space-charge	1140
	B.G. Pine, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the spallation neutron source at Rutherford Appleton Laboratory in the UK. Protons are accelerated from 70 to 800 MeV in a 50 Hz rapid cycling synchrotron. Due to the intense beam, space charge forces are high during the first part of the acceleration cycle. The vacuum vessel in the synchrotron has a rectangular shape where the apertures are conformal to the design beam envelopes. At high intensities image forces interact with the beam, especially when the closed orbit is large. An analysis of image forces has been made and used to classify higher order image terms. These have been identified using simulations of round beams in rectangular vacuum vessels. The higher order image terms from harmonic closed orbits have been used with single particle resonance theory, taking account of the coherent nature of the beam response. Several predictions of beam resonance have been made. A simulation study has been carried out using a smooth focusing lattice and uniform density beams. Resonant beam behaviour has been observed and explained by the proposed theory.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL056
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUZGBE3	Towards Implementation of Laser Engineered Surface Structures for Electron Cloud Mitigation	electron, laser, operation, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE3
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF007	Cryogenic Testing and Initial Performance of a Helical Superconducting Undulator at the APS	undulator, cryogenics, operation, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF007
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMF027	Impedance Modeling for eRHIC	impedance, dipole, quadrupole, electron	1309
	A. Blednykh, G. Bassi, M. Blaskiewicz, C. Hetzel, V. Ptitsyn, V.V. Smaluk, F.J. Willeke BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the US DOE under contract number DE-SC0012704 The impedance budget for the eRHIC project is discussed at its earlier stage of development. As a first step, with the eRHIC lattice and beam parameters , we use the geometric impedances of the vacuum chamber components simulated for the NSLS-II project. The impedance budged will be updated next with more impedance data simulated for the optimized eRHIC vacuum components. It will allows us to keep track on the collective effects changes with more realistic components added to the ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF027
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

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

TUPMF040	Alignment of Current Strips at the Canadian Light Source	alignment, closed-orbit, undulator, electron	1342
	W.A. Wurtz CLS, Saskatoon, Saskatchewan, Canada Q.L. Zhang SINAP, Shanghai, People's Republic of China
	The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source will employ a 180 mm period elliptically polarizing undulator (EPU180), which will have significant impacts on beam dynamics with large tune shifts and reductions in dynamic aperture. Current strips mounted to the vacuum chamber are intended to mitigate the effects of EPU180 with each strip powered by an independent power supply. It is important to accurately model the current strips in order to calculate the required compensation. We model the current strips as straight wires, parallel to the electron beam, with small horizontal and vertical displacements from their nominal positions. As the real current strips are not completely straight, this is an effective model, but justified as we are mostly interested in the magnetic field integrated along the strips. By activating two strips and measuring the ratio of the two currents needed to minimize closed orbit distortion in the horizontal and vertical planes, we can find the effective horizontal and vertical displacements of the straight wires in the model. Our goal is to create an effective model of the strips from beam-based measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF040
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMK002	First Tests of the Apple II Undulator for the LOREA Insertion Device and Front End	undulator, simulation, optics, insertion-device	1488
	J. Campmany, L.G.O. Garcia-Orta, J. Marcos, Z. Martí, V. Massana, M. Quispe ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	ALBA synchrotron is currently installing the new beamline LOREA (Low-Energy Ultra-High-Resolution Angular Photoemission for Complex Materials at ALBA). It operates in the range of 10 - 1500 eV with polarized light. To produce the light for the beamline, an Apple II undulator with a period of 125 mm has been chosen. It can operate as an undulator at low energies and as a wiggler at high energies, providing a wide energy range. The device was built by KYMA, delivered on February 2017 and installed in August 2017. We present the magnetic measurements made during SAT as well as the simulations of the influence of the ID in the electron beam dynamics and the first measurements with beam. On the other hand, the high demanding characteristics of the beamline lead to a device providing high power and wide beam in some working modes. This situation has been a challenge for the Front End (FE) thermal load. It has been built by the companies RMP and TVP, and the FE modules have been installed in the tunnel along autumn 2017. We present the Site Acceptance Tests results as well as the technical solutions adopted, especially in terms of mechanical design and used materials.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK002
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMK010	Differences in Current Dependent Tune Shifts Measured by Direct or ORM Based Methods	storage-ring, impedance, optics, wakefield	1510
	Y.E. Tan, R.T. Dowd AS - ANSTO, Clayton, Australia
	The change in the tunes as a function of total beam current is a well documented effect and has been attributed to quadrupole like self induced wakefields. Theoretical models presented by others have utilised direct methods (spectrum analyser) to measure the tunes in the analysis. In this report we shall present observations that show the ORM method, Linear Optics from Closed Optics (LOCO), and direct methods have significantly different tune gradients. The different tune gradients is attributed to the static (ORM) and dynamic (direct) nature of the measurements where in the static case the vacuum chamber is to be considered as a thin wall while in the dynamic case the vacuum chamber wall is to be considered as a thick wall.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK010
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPML019	Design of Multi-Alkali Photocathode Preparation System for CTFEL Facility	cathode, FEL, laser, electron	1571
	D.X. Xiao, M. Li, Q. Pan, H. Wang, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	The first saturated lasing of the China Academy of Engineering Physics tera-hertz free electron laser (CTFEL) facility has been realized. In order to improve the performance of the CTFEL facility, the multi-alkali photocathode with much longer life-time has been proposed to replace the GaAs photocathode currently used. This paper presents the design of the multi-alkali photocathode preparation system, which consists of three chambers: the suitcase chamber, the preparation chamber, and the loading chamber. The function of each chamber is also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPML025	Long Lifetime Spin-Polarized GaAs Photocathode Activated by Cs2Te	cathode, electron, polarization, photon	1589
	J. Bae, L. Cultrera, P. Digiacomo Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA I.V. Bazarov Cornell University, Ithaca, New York, USA
	Funding: This work was supported by the Department of Energy Grant Nos. DE-SC0016203 and NSF PHY-1461111. High intensity and highly spin-polarized electron source is of great interest to the next generation Electron Ion Colliders. GaAs prepared by the standard activation method, which is the most widely used spin-polarized photocathode, is notorious for its vacuum sensitivity and short operational lifetime. To improve the lifetime of GaAs photocathodes, we activated GaAs by Cs2Te, a material well known for its robustness. We confirmed the Cs2Te layer forms negative electron affinity on GaAs with a factor of 5 improvement in lifetime. Furthermore, the new activation method had no adverse effect on spin-polarization. Considering Cs2Te forms much thicker activation layer (~ 2 nm) compared to the standard activation layer (~ monolayer), our results trigger a paradigm shift on new activation methods with other robust materials that were avoided for their thickness.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML025
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPML073	Ion Source and Low Energy Beam Transport Line Final Commissioning Step and Transfer from INFN to ESS	MMI, proton, ion-source, controls	1712
	L. Celona, A. Amato, G. Calabrese, A.C. Caruso, G. Castro, F. Chines, S. Gammino, O. Leonardi, A. Longhitano, G. Manno, S. Marletta, D. Mascali, A. Maugeri, M. Mazzaglia, A. Miraglia, L. Neri, S. Passarello, A. Seminara, D. Siliato, A. Spartà, G. Torrisi INFN/LNS, Catania, Italy
	At the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), the beam commissioning of the high intensity Proton Source for the European Spallation Source (PS-ESS) was completed in November 2017. All requirements have been satisfied and certified by the European Spallation Source (ESS). In the last step of the commissioning a complete characterization of the source has been carried out and some results are hereinafter reported. The shipment of the source was done in December 2017, followed by the installation in January while the beam commissioning is foreseen during summer 2018. The paper describes the final commissioning steps at INFN-LNS, the procedure adopted for a safe transfer of the equipment, the transfer of knowledge needed for the operation and the maintenance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML073
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPML075	Development of Target/ion Source for Li-8 Beam at KOMAC*	target, ion-source, proton, operation	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML075
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEXGBD1	Development of Very Short Period Undulators	undulator, electron, radiation, factory	1735
	S. Yamamoto KEK, Ibaraki, Japan
	Scientists and engineers at KEK have developed undulator magnets having very short period lengths. Magnet plates 100mm and 152mm long with 4-mm period length have been successfully fabricated. They produce an undulator field of approximately 4kG at a gap of 1.6mm. The magnetic field characterization shows that the undulator field is satisfactory in quality for a very short period undulator. KEK has recently installed a short-period undulator at a 50-MeV linac and observed a first light, and will soon start an experiment using a short-period undulator with laser-accelerated electrons for future table-top XFELs. This invited talk summarizes the current status, and experimental activities and results related to short-period undulators and table-top FELs.
	Slides WEXGBD1 [3.515 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBD1
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF010	Fast Glitch Detection of Coupled Bunch Instabilities and Orbit Motions	feedback, storage-ring, injection, operation	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF010
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF011	Developments of Bunch by Bunch Feedback System at NSLS-II Storage Ring	feedback, operation, emittance, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF011
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF012	Improvements of NSLS-II X-ray Diagnostic Beamlines	emittance, storage-ring, photon, radiation	1837
	W.X. Cheng, B. Bacha, B.N. Kosciuk, D. Padrazo Jr BNL, Upton, Long Island, New York, USA
	Funding: Work supported by DOE contract No: DE-SC0012704 There are two X-ray diagnostic beamlines (XDB) developed at NSLS-II storage ring to measure emittance, energy spread, and other machine parameters. The first beamline utilizes a soft bending magnet radiation has been in operation since 2014. The tungsten pinhole originally located in the air had corrosion issue. The beamline has been improved by extending the vacuum to the imaging system. The second X-ray pinhole beamline using three-pole wiggler (TPW) radiation has been constructed and commissioned recently. Energy spread is able to be precisely measured due to large dispersion at the source point. A gated camera is equipped with the new beamline to acquire profiles within one turn. Recent operation experience and beam measurements will be presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF012
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF049	Energy Beam Position Monitor Button Array Electronics for the European XFEL	electron, FEL, electronics, pick-up	1927
	B. Lorbeer, B. Beutner, H.T. Duhme, L. Fröhlich, D. Lipka, D. Nölle DESY, Hamburg, Germany
	The European XFEL(X-Ray Free Electron Laser) at DESY(Deutsches Elektronen-Synchrotron) in Hamburg/Schenefeld started commissioning in early 2017. Before the pulsed electron beam is accelerated to its final energy of 14 GeV, the energy of the bunch can be compressed in three bunch compression chicanes at 130 MeV, 700 MeV and 2400 MeV. The vacuum chamber in these sections is tapered from 40 mm round beam pipe to a 40 cm rectangular shaped vacuum section. A custom made button array type of BPM(Beam position Monitor) is installed in this section with 26 button electrode feed-throughs. The analog and digital readout electronics for this monitor and the first experience with the calibration and operational aspects of this system are presented in this poster.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF049
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAF068	Frequency Scanning Interferometry as New Solution for on-Line Monitoring Inside a Cryostat for the HL-LHC project	cavity, target, monitoring, dipole	1986
	H. Mainaud Durand, T. Dijoud, J. Gayde, F. Micolon, M. Sosin CERN, Geneva, Switzerland M. Duquenne, V. Rude ESGT-CNAM, Le Mans, France
	Funding: Research supported by the HL-LHC project For the HL-LHC project, the cryostats of the key components will be equipped permanently with an on-line position monitoring system based on Frequency Scanning Interferometry (FSI). Such a system, based on absolute distance measurement, will determine the position of the inner triplet cold masses w.r.t. their cryostat and the position of the crab cavities also inside their cryostat, within an uncertainty of measurement of 0.1 mm, in a harsh environment: cold temperature of 2 K and high radiation level of the order of 1 MGy. The FSI system was validated first successfully on one LHC dipole cryostat and its associated cold mass to undergo qualification tests under different conditions: warm, vacuum and cold (2K). The FSI system also equips the first crab cavities prototype cryostat. The configuration of the FIS system chosen after simulations, the conditions of tests as well as their results and analysis are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF068
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL014	Non-Distructive 2-D Beam Profile Monitor Using Gas Sheet in J-PARC LINAC	linac, injection, electron, cavity	2177
	J. Kamiya, Y. Hikichi, M. Kinsho, A. Miura, N. Ogiwara JAEA/J-PARC, Tokai-mura, Japan
	We have been developed a beam profile monitor using interaction between the beam and the gas molecules distributed in sheet shape. Generated luminescence or ions by passing the beam through the gas sheet has the information of cross-section shape of the beam. The gas sheet beam monitor will become a useful tool to measure the profile of high power beams because it has no breakable element such as wires and a 2-D beam profile at a certain position of beam line can be immediately obtained by just injecting the gas. Previously, the development of the gas sheet generator and successful demonstration of the beam profile measurement were reported. This time, we applied a gas sheet monitor to J-PARC LINAC, where the negative hydrogen atoms (H⁻) are accelerated to the energy of 400 MeV in the normal operation. Most challenging factor was the development of the gas sheet monitor system, which generates the enough dense gas sheet to detect the clear image of the beam profile without harmful effect on the ultra-high vacuum in the beam line. We will report the gas sheet beam monitor system for J-PARC LINAC and the results of the first measurement of the beam profile. N. Ogiwara, et al., Proceedings of IPAC2016, p.2102.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL014
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAL058	Beam Loss Studies at the Taiwan Photon Source	radiation, injection, scattering, undulator	2309
	C.H. Huang, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu NSRRC, Hsinchu, Taiwan
	PIN-photodiodes and RadFETs are installed in the storage ring of the Taiwan Photon Source (TPS) to study beam loss distributions and mechanisms. In the highest dose area, the radiation comes mainly from hard X-rays produced by synchrotron bending magnets. During beam cleaning and after replacing a vacuum chamber, losses due to inelastic Coulomb scattering occur mostly downstream from bending magnets while elastic scattering causes electrons to get lost mainly after an elliptically polarizing undulator which has a limited vertical aperture. During the injection period, the beam loss pattern can be changed by modifying injection conditions or lattice settings. The beam loss usually happens in the injection section and small-aperture section. The injection efficiency can be improved by minimizing the detected injection loss.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL058
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF004	The Saclay Test Stand for Conditioning the ESS RFQ Power Couplers at High RF Power	cavity, rfq, linac, interface	2375
	N. Misiara, A.C. Chauveau, D. Chirpaz-Cerbat, P. Daniel-Thomas, M. Lacroix, L. Maurice CEA/IRFU, Gif-sur-Yvette, France M. Desmons, A. Dubois, A. Gaget, L. Napoly, M. Oublaid, G. Perreu, O. Piquet, B. Pottin, Y. Sauce CEA/DRF/IRFU, Gif-sur-Yvette, France
	The RF power coupler system for the RFQ of the ESS LINAC will feed 1.6 MW peak power through two coaxial loop couplers for a 352.21 MHz operation at the expected duty cycle. A specific test stand has been designed to condition the power couplers, and test the different auxiliary components in the nominal conditions of the RFQ. The power couplers were successfully assembled, installed and instrumented on the test cavity. This paper presents the general layout of the test stand, the installation and preparation of the power couplers for their conditioning at high RF power up to the ESS nominal conditions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF004
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF009	Influence of Argon-Ion Irradiation on Field Emission from Polycrystalline Cu and Large-Grain NB Surfaces	radiation, niobium, experiment, cavity	2384
	S. Soykarci University of Wuppertal, Wuppertal, Germany D. Lützenkirchen-Hecht, V. Porshyn, P. Serbun Bergische Universität Wuppertal, Wuppertal, Germany
	Funding: This work is funded by the BMBF project 05H15PXRB1. In the present work, systematic investigations of the enhanced field emission (EFE) from polycrystalline copper and large grain niobium surfaces before and after argon-ion irradiation with an energy of 5 keV were performed with a variation of the irradiation time. Results show that the suppression of the EFE might be achievable.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF009
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF022	Coulped Multiphysics Simulation for the Water Cooling Layout of a Rhodotron Cavity	cavity, simulation, operation, electron	2416
	L. Yang, X. He, H. Li, S.Q. Liao CAEP/IFP, Mainyang, Sichuan, People's Republic of China
	A Rhodotron-based electron accelerator served as micro-focused X-ray source is under development at IFP, CAEP. The RF-cavity, running in long pulse/ CW mode, will deliver 9 MeV energy to electron beams after multiple accelerations within the same field at a frequency of 10⁷.5MHz. A substantial amount of average power loss with tens of kW will be dissipated on the RF surface of the cavity to maintain the operational field level. Efficient water cooling is critical to prevent large scale temperature rise for stable operation sake. Reasonable prediction of temperature rise becomes essential to assess a certain cooling layout in the design phase. The frequency drift and thermal stress on account of temperature variation and gradient on cavity wall respectively, could be computed accordingly. This paper presents a comprehensive coupled simulation involving electromagnetic, thermal and structural for the RF-cavity of Rhodotron.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF022
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF031	Development of a High-Power High-Directivity Directional Coupler and Four Power Dividers for S-Band	coupling, GUI, MMI, simulation	2422
	X. He, J. Lei, J.R. Zhang IHEP, Beijing, People's Republic of China
	A novel Bethe-hole S band directional coupler has been designed based on some structural optimizations, the prototype has been tested with a Directivity of more than 30 dB. The new directional coupler can also hold higher power compared to the old type, which is more useful for the future accelerator applications. Four power dividers using different structures are studied and the best one is chosen for fabrication. The prototype with matching rod in the middle has got qualified microwave cold test results and has been used during the whole microwave commissioning of an accelerating structure, the performance is quite stable.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF031
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF032	Experimental Studies on Secondary Electron Emission Characteristics for Chamber Materials of Accelerators	electron, experiment, detector, neutron	2425
	Y. Jiao, Z. Duan, W.B. Liu, Y.D. Liu IHEP, Beijing, People's Republic of China Liu. S. Liu Institute of High Energy Physics (IHEP), People's Republic of China P.C. Wang DNSC, Dongguan, People's Republic of China
	Funding: National Natural Science Foundation of China (11275221) and Key Laboratory Foundation of Particle Acceleration Physics &Technology (Y5294106TD) Secondary electron emission (SEE) of surface is origin of multipacting effect which could seriously deteriorate beam quality and even perturb the normal operation of particle accelerators. Experimental measurements on secondary electron yield (SEY) on different materials and coating have been developed in many accelerator laboratory. In fact, the SEY is just one parameter of secondary electron emission characteristics which include spatial and energy distribution of emitted electrons. A novel experimental apparatus was set up in China Spallation Neutron Source (CSNS) and innovative measurement methods were applied to obtain the whole characteristics of SEE. With some traditional accelerator chamber materials such as Cu, Al, TiN, SEY dependence on primary electron energy and beam injection angle, spatial and energy distribution of emitted secondary electrons were achieved with this measurement apparatus. This contribution also tries to give all the experimental results a reasonable theoretical analysis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF032
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF033	RF Study And Cold Test of an S-band Spherical Cavity Pulse Compressor	cavity, coupling, simulation, klystron	2429
	J. Lei, X. He, M. Hou, X.P. Li, G. Pei, H. Wang, J.B. Zhao IHEP, Beijing, People's Republic of China S. Shu Institute of High Energy Physics (IHEP), Chinese Academy of Sciences, Beijing, People's Republic of China
	An S-band (2856 MHz) spherical cavity pulse compressor has been designed, fabricated and tested in the Institute of High Energy Physics (IHEP), Chinese Academy of Sciences (CAS). The pulse compressor consists of a special 3 dB coupler and only one spherical energy storage cavity, two TE114 modes are chosen to oscillate in which for fairly high unload Q factor. The prototype was made of aluminum for studying the performance of the pulse compressor and checking the validity of the simulations. The cold test results of the aluminum cavity are also presented. The copper coating on the whole internal surface of the aluminum spherical cavity is in progress and the test results will also be presented in the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF033
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF036	RF Test Result of a BNL N-Doped 500 MHz B-Cell Cavity at Cornell	cavity, SRF, superconducting-cavity, niobium	2440
	F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, M. Liepe, J.T. Maniscalco, J. Sears Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA F. Gao, J. Rose BNL, Upton, Long Island, New York, USA
	Cornell's SRF group has collaborated with Brookhaven National Laboratory (BNL) on one 500 MHz CESR type SRF "B-cell" cavity (BNL B-cell) for the National Synchrotron Light Source II. Cornell has been responsible for RF surface preparation, vertical testing, and short cavity string assembly. As a state-of-the-art surface preparation protocol, Cornell selected Nitrogen doping for the BNL B-cell. N-doping has been well demonstrated and established to push the cavity quality factor (Q0) higher in 1.3GHz SRF cavities at many laboratories. Cornell calculated that N-doping could also be beneficial on a 500MHz SRF cavity, with a potential to increase its Q0 by a factor of two compared with the traditional chemical polishing based surface preparation protocol. Here we report on the detailed surface preparation and vertical test result of the BNL B-cell.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF036
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF039	Experimental Results on the Field and Frequency Dependence of the Surface Resistance of Niobium Cavities	cavity, niobium, experiment, electron	2451
	P.N. Koufalis, M. Liepe, J.T. Maniscalco, T.E. Oseroff Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	We investigate the field and frequency dependence of the surface resistance of single-cell niobium cavities as a function of surface treatment at 1.3, 2.6, and 3.9 GHz. The surface resistance is broken down into two parts: the temperature-independent residual resistance and the temperature-dependent BCS resistance. While the low-field BCS resistance is known to vary quadratically with frequency, the exact dependence of the BCS and residual resistances on field at higher frequencies are important topics for further investigation. We offer results on a systematic experimental study of the residual and BCS resistance as a function of frequency and field for clean niobium and high-temperature nitrogen-doped niobium.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF039
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF055	The REGAE Accelerator Vacuum System	gun, cathode, operation, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF055
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF057	PETRA III Vacuum System - Experiences from the First Decade of Operation	operation, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF057
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF066	Fabrication of Split-Section X-band Structure Using Elastic Averaging	alignment, coupling, electron, gun	2521
	P. Borchard, S.A. Appert, J.S. Hoh Dymenso LLC, San Francisco, USA
	Conventional accelerator structures are manufactured using axial stacks of cylindrical components which, when brazed together, form the accelerator cell structure. Splitting the accelerator structure into two sections along the beam axis allows for a significant reduction in part count and vacuum joint length. The resultant single and coplanar vacuum joint between the two split sections allows for joining techniques such as electron beam welding or brazing of the parts to form the accelerator vacuum envelope. High precision alignment of the two sections is achieved through an elastic averaging interface coupling where improved accuracy is derived from the averaging of errors over a large number of relatively compliant contacting members. The monoblock split sections allow for highly optimized cooling configurations with enhanced heat removal in high heat flux regions, reducing vacuum wall thermal stresses and enabling higher power operation. This paper describes the engineering and manufacturing of four generations of brazed and electron beam welded X-band accelerator structures at both 9.3 GHz and 11.4 GHz frequencies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF066
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF068	Inexpensive Brazeless Accelerator Prototype	gun, cavity, operation, electron	2528
	S.P. Antipov, R.A. Kostin, S.V. Kuzikov Euclid TechLabs, LLC, Solon, Ohio, USA A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	Funding: DOE SBIR A simple, inexpensive way to manufacture a standard radio frequency (RF) driven particle accelerator is presented. The simplification comes from two innovations: utilization of LCLS gun type RF design to avoid an expensive brazing process and copper plating of stainless steel that further reduces manufacturing cost. This is realized by a special structure design where accelerating structure cells are made out of copper plated stainless steel with knife edges and structure irises - copper disks acts also as gaskets for vacuum and RF seal. Besides the reduced cost, brazeless assembly allows integration of effective cooling and magnet optics elements into accelerator cells. Here we report on manufacturing and testing of brazeless accelerator prototype.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF068
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF074	High Power Conditioning of X-Band RF Components	operation, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF074
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF078	Assembly of the DQW Crab Cavity Cryomodule for SPS Test	cavity, cryomodule, controls, alignment	2561
	M. Garlaschè, K. Artoos, R. Calaga, O. Capatina, T. Capelli, N. El Kbiri, D. Lombard, P.F. Marcillac, P. Minginette, M. Narduzzi, L.R.A. Renaglia, J. Roch, J.S. Swieszek CERN, Geneva, Switzerland A. Krawczyk, B. Prochal IFJ-PAN, Kraków, Poland
	RF Crab Cavities are an essential part of the High Luminosity Upgrade of the LHC accelerating complex. Two concepts of such superconducting systems are being developed: the Double Quarter Wave (DQW) and the RF Dipole (RFD). A prototype cryomodule - hosting two DQW cavities - has been fabricated and assembled for validation tests to be carried out in the Super Proton Synchrotron (SPS) at CERN. An overview of the main cryomodule components is presented, together with the system features and main fabrication requirements. The preparatory measures for cryomodule assembly, the execution and lessons learned are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF078
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF082	Design and Construction of the CERN PS Booster Charge Exchange Injection Chicane Bumpers	injection, septum, simulation, linac	2575
	B. Balhan, C. Baud, J.C.C.M. Borburgh, M. Hourican CERN, Geneva, Switzerland
	In the framework of the LIU project and the connection from LINAC4 to PS Booster, the 160 MeV H⁻ beam will be injected horizontally into the PSB by means of one charge-exchange injection system for each PSB ring. A set of four outside vacuum pulsed dipole magnets (BSW) creating the required injection bump has been designed and built. The dynamic requirements for the bump ramp down determine, to a large extent, the field homogeneity due to the eddy currents induced in the corrugated Inconel vacuum chamber. Magnetic simulations were performed to determine the field harmonics during bump ramp down, and the results subsequently used for the dynamic tracking of the beam during injection. The mechanical design and construction of the magnets will be briefly outlined, and the article will conclude with the magnetic measurements of the magnets. The magnetic performance of the as built magnets will be compared with the simulations and the influence of the vacuum chambers on the magnetic field will be quantified.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF082
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF087	LHC Injectors Upgrade Project: Outlook of the Modifications to the Super Proton Synchrotron (SPS) Vacuum System and Impact on the Operation of the Carbon-Coated Vacuum Chambers	impedance, experiment, proton, extraction	2589
	C. Pasquino, G. Bregliozzi, P. Chiggiato, P. Cruikshank, A. Farricker, A. Harrison, J. Perez Espinos, J.A.F. Somoza, M. Taborelli, C. Vollinger CERN, Geneva, Switzerland
	Aiming at doubling the beam intensity and reducing the beam emittance, significant modifications of the LHC and its injector chain will take place during Long Shutdown 2 (LS2), starting from 2019. The LIU project (LHC Injector Upgrade), in the specific, touches Linac4, the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS) as well as the heavy ion chain. During LS2, important changes will take place mainly in the Long Straight Sections of the SPS to host a newly conceived dumping system, upgraded RF cavities and upgraded extraction channels. Additionally, the vacuum chambers of the main bending and focusing magnets as well as vacuum drifts will be coated with amorphous carbon in order to reduce the dynamic pressure effects induced by multipacting. The modifications to the different vacuum sectors will be described in details as well as the impact on operation of amorphous carbon coated sectors that have been already deposited.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF087
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMF090	Upgrade of the CMS Experimental Beam Vacuum During LS2	experiment, detector, operation, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF090
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMG001	Engineering Design and Prototyping of the New LIU PS Internal Beam Dumps	simulation, interface, proton, operation	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMG001
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMG005	First Beam Test of Laser Engineered Surface Structures (LESS) at Cryogenic Temperature in CERN SPS Accelerator	electron, laser, cryogenics, multipactoring	2616
	R. Salemme, V. Baglin, S. Calatroni, P. Chiggiato, B. Di Girolamo, E. Garcia-Tabares Valdivieso, B. Jenninger, L. Prever-Loiri, M. Sitko CERN, Geneva, Switzerland A. Abdolvand, S. Wackerow University of Dundee, Nethergate, Dundee, Scotland, United Kingdom R. Salemme ITER Organization, St. Paul lez Durance, France
	Electron cloud mitigation is an essential requirement for accelerators of positive particles with high intensity beams to guarantee beam stability and limited heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) are being considered, within the High Luminosity upgrade of the LHC collider at CERN (HL-LHC), as an option to reduce the Secondary Electron Yield (SEY) of the surfaces facing the beam, thus suppressing the elec-tron cloud phenomenon. As part of this study, a 2.2 m long Beam Screen (BS) with LESS has been tested at cryogenic temperature in the COLD bore EXperiment (COLDEX) facility in the SPS accelerator at CERN. In this paper, we describe the manufacturing procedure of the beam screen, the employed laser treatment technique and discuss our first observations in COLDEX confirming electron cloud suppression.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMG005
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK001	Preliminary Design of a Cooling System for the LHC Injection Kicker Magnets	kicker, injection, operation, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK001
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK002	Longitudinal Impedance Analysis of an Upgraded LHC Injection Kicker Magnet	impedance, kicker, simulation, injection	2628
	V. Vlachodimitropoulos, M.J. Barnes, L. Vega Cid, W.J.M. Weterings CERN, Geneva, Switzerland
	Prior to Long Shutdown 1 (LS1) one of the LHC injection kickers (MKIs) occasionally exhibited high temperatures leading to significant turnaround times. After a successful impedance mitigation campaign during LS1, the MKI ferrite yokes have remained below their Curie point and have not limited LHC's availability. However, for HL-LHC operation the MKI yokes are expected to exceed their Curie temperatures after long physics runs. To ensure uninterrupted future HL-LHC operation, a modified beam screen design, relocating some of the heat load to more easily cooled parts, and a suitable cooling system are under development as the current baseline for the HL-LHC upgrade of the MKIs. An upgraded beam screen providing such relocation has been designed, simulated and compared to the existing model. To validate simulations, two longitudinal beam coupling impedance measurement techniques have been used and the results are compared to predictions. The modified beam screen was implemented in an upgraded MKI installed in the LHC during the Year End Technical Stop (YETS) 2017/18.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK002
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK003	An Upgraded LHC Injection Kicker Magnet	kicker, injection, electron, impedance	2632
	M.J. Barnes, C. Bracco, G. Bregliozzi, A. Chmielinska, L. Ducimetière, B. Goddard, T. Kramer, H. Neupert, L. Vega Cid, V. Vlachodimitropoulos, W.J.M. Weterings, C. Yin Vallgren CERN, Geneva, Switzerland A. Chmielinska EPFL, Lausanne, Switzerland
	Funding: Work supported by the HL-LHC project. An upgrade of the LHC injection kickers is necessary for HL-LHC to avoid excessive beam induced heating of these magnets: the intensity of the HL-LHC beam will be twice that of LHC. In addition, in the event that it is necessary to exchange an injection kicker magnet, the newly installed kicker magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. Extensive studies have been carried out to identify practical solutions to these problems: these include redistributing a significant portion of the beam induced power deposition to ferrite parts of the kicker magnet which are not at pulsed high voltage and water cooling of these parts. Furthermore a surface coating, to mitigate dynamic vacuum activity, has been selected. The results of these studies, except for water cooling, have been implemented on an upgraded LHC injection kicker magnet: this magnet was installed in the LHC during the 2017-18 Year End Technical Stop. This paper presents the upgrades, including some test and measurement results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK003
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPMK010	LCLS-II Cryomodules Production at Fermilab	cryomodule, cavity, FEL, controls	2652
	T.T. Arkan, J.N. Blowers, C.M. Ginsburg, C.J. Grimm, J.A. Kaluzny, A. Lunin, Y.O. Orlov, K.S. Premo, R.P. Stanek, G. Wu Fermilab, Batavia, Illinois, USA
	Funding: DOE LCLS-II is a planned upgrade project for the linear coherent light source (LCLS) at SLAC. The LCLS-II linac will consist of thirty-five 1.3 GHz and two 3.9 GHz superconducting RF continuous wave (CW) cryomodules that Fermilab and Jefferson Lab are currently producing in collaboration with SLAC. The LCLS-II 1.3 GHz cryomodule design is based on the European XFEL pulsed-mode cryomodule design with modifications needed for CW operation. Two prototype cryomodules had been assembled and tested. After prototype cryomodule tests, both laboratories have increased cryomodule production rate to meet the challenging LCLS-II project installation schedule requirements of approximately one cryomodule per month per laboratory. Fermilab is at half point for the production, meaning that 6 cryomodules are fully assembled and tested. This paper presents Fermilab Cryomodule Assembly Facility (CAF) infrastructure for the LCLS-II cryomodules assembly, production experience at the half point emphasizing the challenges and mitigations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK010
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML014	Tooling Systems for the Assembly and Integration of the SSR1 Cryomodule for PIP-II Project at Fermilab	cavity, cryomodule, solenoid, insertion	2710
	D. Passarelli, F. Di Ciocchis, M. Parise, V. Roger Fermilab, Batavia, Illinois, USA
	In this paper we present the assembly strategy and tooling design for the SSR1 cryomodule from the cavity string to the final module. Several challenging aspects were considered to minimize undesired stresses on critical components, to preserve the alignment of cavities and solenoids during final assembly, and ultimately to meet the technical requirements of the PIP-II project at Fermilab.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML014
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML015	Preparation and Qualification of Jacketed SSR1 Cavities for String Assembly at Fermilab	cavity, cryomodule, multipactoring, controls	2714
	D. Passarelli, P. Berrutti, S.K. Chandrasekaran, J.P. Ozelis, M. Parise, L. Ristori, A.M. Rowe, A.I. Sukhanov Fermilab, Batavia, Illinois, USA
	The qualification of dressed 325 MHz Single Spoke Resonators type 1 (SSR1) to meet technical requirements is an important milestone in the development of the SSR1 cryomodule for the PIP-II Project at Fermilab. This paper reports the procedures and lessons learned in processing and preparing these cavities for horizontal cold testing prior to integration into a cavity string assembly.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML015
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML028	NEG Coated Vacuum Chambers and Bake-Out-Concept for the HESR at FAIR	dipole, quadrupole, heavy-ion, storage-ring	2745
	H. Jagdfeld, N.B. Bongers, J. Böker, P. Chaumet, F.M. Esser, F. Jordan, F. Klehr, G. Langenberg, D. Prasuhn, L. Semke, R. Tölle FZJ, Jülich, Germany A. Mauel, G. Natour, U. Pabst Forschungszentrum Jülich GmbH, Central Institute of Engineering, Electronics and Analytics, Jülich, Germany
	The High-Energy Storage Ring (HESR) is part of the international Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt. Forschungszentrum Jülich (IKP and ZEA-1) is responsible for the design and installation of the HESR. The HESR is designed for antiprotons and heavy ion experiments as well. Therefore the vacuum is required to be 10^-11 mbar or better. To achieve this extreme high vacuum (XHV), NEG coated chambers will be used in combination with common vacuum pumps to reach the needed pumping speed and capacity everywhere in the accelerator ring. For activation of the NEG material a bake-out system will be developed and installed. A bake-out test bench was used for checking the achievable end pressure and developing the bake-out system for the NEG coated chambers of the HESR. The results of the tests and the bake-out concept including the layout of the control system are presented. In addition, the temperature distribution of the dedicated heater jackets inside the dipole and quadrupole magnets are shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML028
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML029	Vacuum System of the HESR at FAIR, Status of Tests, Layout and Manufacturing	dipole, kicker, injection, controls	2748
	F.M. Esser, N.B. Bongers, J. Böker, P. Chaumet, R. Gebel, R. Greven, S. Hamzic, H. Jagdfeld, F. Klehr, B. Laatsch, G. Langenberg, D. Marschall, A. Mauel, G. Natour, D. Prasuhn, L. Reifferscheidt, M. Schmitt, L. Semke, R. Tölle FZJ, Jülich, Germany
	The Research Center Jülich is leading a consortium being responsible for the design and manufacturing of the High-Energy Storage Ring (HESR) which is part of the FAIR project in Darmstadt, Germany. The HESR is designed for antiprotons within a momentum range of 1.5-15 GeV/c but can also be used for heavy ion experiments. Therefore the vacuum quality is expected to be 10^-11 mbar or better which is a great challenge on the overall vacuum layout as well as on the surface quality of the chambers and beam tubes. Whereas all bent dipole chambers are installed, the manufacturing of the pumping bodies with integrated RF meshes as well as several diagnostic chambers are in the focus of investigation. To validate the intended pumping concept of both the bake-out arc sections and the non-bakable straight sections, final tests at the operational test benches are planned. In parallel, the purchasing of valves and first pumps will be prepared. The actual layout of the HESR vacuum system and its components will be presented as well as the progress of manufacturing of several vacuum chambers. The latest experimental test results will be presented also.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML029
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML038	Plasma Window as a Pressure Valve for FAIR	plasma, cathode, experiment, electron	2776
	B. F. Bohlender, M. Iberler, J. Jacoby IAP, Frankfurt am Main, Germany A. Michel Goethe Universität Frankfurt, Frankfurt am Main, Germany
	Funding: Funded by BMBF, Ref. No: 05P15 RFRBA and HIC for FAIR This contribution shows the progress in the development of a plasma window at the institute for applied physics at Goethe University Frankfurt. A plasma window* is a membrane free transition between two regions of different pressure, enabling beam transmission from a rough vacuum area (~1 mbar) to a higher pressure (up to 1 bar) region on short length scales. In comparison to differential pumping stages a length reduction by a factor of up to 100 is achievable, while the absence of a solid membrane yields prolonged operation time. The sealing effect is based on the high temperature arc discharge sustained in a cooled copper channel between the pressure regimes. Due to a bulk temperature around 10,000K** the viscosity of the gas is dramatically increased, leading to a slower gas flow, enabling a higher pressure gradient. This contribution will present first results regarding the pressure gradient in dependence of the discharge current and the aperture. Until now, a pressure factor around 100 has been established for well over 50 min. This contribution goes along with the one from Mr. A. Michel, he focuses on the spectroscopic analysis of the arc plasma. A. Hershcovitch, J. Appl. Phys., AIP Publishing (1995) 78, 5283 *Y.E. Krasik et al., "Plasma Window Characterization", J. Appl. Phys., AIP Publishing (2007) 101, 053305.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML038
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML045	Infrastructure for Superconducting CH-Cavity Preparation at HIM	cavity, linac, SRF, heavy-ion	2796
	T. Kürzeder, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, M. Miski-Oglu, E. Riehn HIM, Mainz, Germany K. Aulenbacher, R.G. Heine, T. Stengler IKP, Mainz, Germany W.A. Barth, S. Yaramyshev GSI, Darmstadt, Germany F. Hug KPH, Mainz, Germany
	A superconducting cw LINAC for heavy ions is currently under development at GSI in Darmstadt and HIM in Mainz. This Linac is based on 217 MHz multigap bulk niobium Crossbar H-mode RF-cavities. In order to treat and prepare RF-cavities with such a complex geometry a new cleanroom facility has been already built at the Helmholtz-Institut in Mainz. All tools and machines inside the cleanroom can handle cavities with up to 800 mm in diameter and with up to 1300 mm in length. In its ISO-class 6 and 4 zones, respectively it features a large ultrasonic and conductance rinsing bath, a high pressure rinsing (HPR) cabinet and a vacuum oven. The HPR cabinet has an inside clearance of 1.4 m. The large cavities sit on a rotating table, while the rising wand moves vertically up and down. Due to the crossbar structure of the RF-cavities the HPR device allows for off axis-rinsing in their quadrants. For RF testing a 52 m² (4 m x 13 m) concrete shielded area with sufficient liquid helium and nitrogen supply is located next to the cleanroom and the cryo-module assembly area. We will report on the new SRF infrastructure in Mainz and the commissioning of the new high pressure rinsing cabinet.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML045
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML053	Availability of the TiN Coating-Free Ceramic in the STF-type Power Coupler for ILC	electron, SRF, cryomodule, GUI	2819
	Y. Yamamoto, E. Kako, T. Matsumoto, S. Michizono, A. Yamamoto KEK, Ibaraki, Japan M. Irikura, M. Ishibashi, H. Yasutake Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan C. Julie, E. Montesinos CERN, Geneva, Switzerland
	In the Superconducting RF Test Facility (STF) in KEK, the research and development for the power coupler with the TiN coating-free ceramic has been done from 2014. In 2016, the high power test at the test bench was stopped due to the worse vacuum level by the unusual heating around the RF window with the TiN coating-free ceramic and the coaxial tapered section, which was caused by the enormous emission of the secondary electrons from the ceramic. And, the situation was never also changed by the ultrapure water rinsing for the power couplers several times. However, in 2017, the ultrasonic rinsing was done for the power couplers for the first time by the collaboration between KEK and TETD. After that, the situation was drastically improved, and the secondary electron emission almost disappeared even in the higher RF duty. This shows that the TiN coating-free ceramic is the prospective item for the cost reduction in ILC. In this report, the recent result for the power coupler with the TiN coating-free ceramic will be presented in detailed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML053
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML057	First Commissioning of Vacuum System of Positron Damping Ring for SuperKEKB	photon, MMI, operation, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML057
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML059	Status of the SuperKEKB Vacuum System in the Phase-2 Commissioning	MMI, electron, wiggler, permanent-magnet	2833
	Y. Suetsugu, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, S. Terui KEK, Ibaraki, Japan
	The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8.0·10³⁵ /cm²/s. 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, several problems were found for the future commissioning, and various countermeasures were taken against these problems during the shutdown period before starting the Phase-2 commissioning. For example, permanent magnets were placed around the beam pipe to suppress the electron cloud effect in the positron ring. Other than these works, new beam pipes for the collision point, the super-conducting final focusing magnets and the positron beam injection region were installed in the main ring. Additional six beam collimators were installed for reducing background noise of the particle detector. Furthermore, the vacuum system for new damping ring for the positron beam was constructed. Reported here will be the present status of the vacuum system of the main ring, and major results of the countermeasures taken prior to the Phase-2 commissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML059
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML069	Fast Kicker and Pulser R&D for the HEPS on-Axis Injection System	kicker, injection, impedance, simulation	2846
	H. Shi, J. Chen, Z. Duan, L. Huo, P. Liu, X.L. Shi, G. Wang, L. Wang, N. Wang IHEP, Beijing, People's Republic of China
	The HEPS plans to adopt on-axis injection scheme because the dynamic aperture of machine is not large enough for off-axis injection for its baseline 7BA lattice design. A sets of super fast kicker and pulser of ±15kV amplitude, 15ns pulse bottom width are needed for bunch spacing of 10ns to minimize perturbation on adjacent bunches. To achieve these requirement, a multifaceted R&D program including the strip-line kicker and HV pulser, was initiated last 2 years. So far, the prototype development of a 750mm long strip-line kicker and a DSRD pulser was completed and the preliminary test results show they can meet the baseline requirement of the HEPS.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML069
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML071	Superconducting 16-Pole Wiggler for Beijing Electron-Positron Collider II	wiggler, impedance, collider, positron	2853
	M.X. Li, X.J. Bian, F.S. Chen, W. Chen, X.J. Sun, H. Wang, J.L. Wang, N. Wang, M.F. Xu, X.C. Yang IHEP, Beijing, People's Republic of China
	A superconducting 16-pole 2.6T wiggler with period 170mm of The High-Energy Photon Source and the Test Facility Project (HEPS-TF) designed and fabricating in the Institute of High Energy Physics (IHEP) in China is described. This wiggler will be installed in Beijing Electron-Positron Collider II (BEPCII). The main parameters and structure of the wiggler are presented. Besides, some vertical testing results are involved.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML071
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML072	Gas Permeability Measurement of Graphene Films	background, experiment, neutron, detector	2856
	P.C. Wang, X. Sun DNSC, Dongguan, People's Republic of China Liu. S. Liu Institute of High Energy Physics (IHEP), People's Republic of China C. Meng, H. Wang, D.H. Zhu IHEP, Beijing, People's Republic of China
	Graphene has extremely high strength and thermal conductivity, which can possibly be used for high-power beam window in accelerator. In this paper, gas permeabilities of different graphene films have been measured by the permeation measurement facility. According to the results, the possibility of the graphene-made beam windows will be discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML072
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THXGBD3	Status of the ESRF-Extremely Brilliant Source Project	SRF, operation, 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]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBD3
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THXGBF2	Beam Commissioning of the IFMIF EVEDA Very High Power RFQ	rfq, cavity, MMI, operation	2902

Paper

Title

Other Keywords

Page

MOZGBE3

Primary Study of High-Power Graphene Beam Window

Windows, proton, target, scattering

47

H. Wang, C. Meng, H. Qu, D.H. Zhu
IHEP, Beijing, People's Republic of China
X. Sun, P.C. Wang
DNSC, Dongguan, People's Republic of China

Beam windows are usually used to isolate vacuum or other special environments, which is a key device for high-power accelerators. Graphene has extremely high thermal conductivity, high strength and high transparency to high energy ions. It is highly suitable for beam windows if the technology is allowable. This paper will discuss the primary tests of graphene films, including vacuum per-formance and thermal conductivity performance, as well as the simulated performance of an assumed graphene window.

Slides MOZGBE3 [1.751 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE3

Export •

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

MOZGBE4

Overview of Fabrication Techniques and Lessons Learned with Accelerator Vacuum Windows

Windows, target, operation, 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

Export •

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

MOZGBE5

Results on the FCC-hh Beam Screen at the KIT Electron Storage Ring KARA

photon, electron, experiment, radiation

55

L.A. Gonzalez, V. Baglin, P. Chiggiato, C. Garion, M. Gil Costa, R. Kersevan
CERN, Geneva, Switzerland
I. Bellafont, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
S. Casalbuoni, E. Huttel
KIT, Eggenstein-Leopoldshafen, Germany

Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union's Horizon 2020 research and innovation programme under grant No 654305.
In the framework of the EuroCirCol collaboration* (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of 3 FCC-hh beam-screen (BS) prototypes has been carried out with the aim of testing them at room temperature at the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator). The 3 BS prototypes will be tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power, match the one foreseen for the 50+50 TeV FCC-hh proton collider. Each of the 3 BS prototypes, 2 m in length, implement a different design feature: 1) baseline design (BD), with electro-deposited copper and no electron-cloud (EC) mitigation features; 2) BD with set of distributed cold-sprayed anti-EC clearing electrodes; 3) BD with laser-ablated anti-EC surface texturing. We present here the results obtained so far at BESTEX and the comparison with extensive montecarlo simulations of the expected outgassing behavior under synchrotron radiation.
The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information.

Slides MOZGBE5 [4.318 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE5

Export •

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

MOPMF031

Modelling Wake Impedance of a Rough Surface in Application to the FCC-hh Beamscreen

impedance, coupling, electron, laser

157

S. Arsenyev, D. Schulte
CERN, Geneva, Switzerland

The inner surface of the future circular collider (FCC-hh) beamscreen is proposed to be laser-treated in order to mitigate the electron cloud build-up. However, the rough structure of the treated surface can result in unwanted impedance increase, potentially leading to the transverse mode coupling instability (TMCI). Three models have been adopted to estimate the wake impedance of a beamscreen with a rough surface. The models use the resistive wall formalism generalized for the case of an arbitrary surface impedance. The results apply to a beamscreen of a circular cross-section with the homogeneously rough inner surface for the case of ultrarelativistic particles. The free parameters of the models were fit into preliminary measurements of the surface resistivity, giving, as a result, a range of the real and the imaginary parts of the wake impedance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF031

Export •

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

MOPMF053

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

MMI, operation, electron, 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

Export •

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

MOPMF070

High Voltage Design for the Electrostatic Septum for the Mu2e Beam Resonant Extraction

cathode, high-voltage, simulation, extraction

289

M.L. Alvarez, C.C. Jensen, D.K. Morris, V.P. Nagaslaev, H. Pham, D.G. Tinsley
Fermilab, Batavia, Illinois, USA

Two electrostatic septa (ESS) are being designed for the slow extraction of 8GeV proton beam for the Mu2e experiment at Fermilab. Special attention is given to the high voltage components that affect the performance of the septa. The components under consideration are the high voltage (HV) feedthrough, cathode standoff (CS), and clearing electrode ceramic standoffs (CECS). Previous experience with similar HV systems at Fermilab was used to define the evaluation criteria of the design of the high voltage components. Using electric field simulation software, high E-field intensities on the components and integrated field strength along the surface of the dielectric material were minimized. Here we discuss the limitations found and improvements made based on those studies.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF070

Export •

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

MOPMF085

Beam-gas Background Characterization in the FCC-ee IR

simulation, scattering, background, optics

322

M. Boscolo, O.R. Blanco-García
INFN/LNF, Frascati (Roma), Italy
H. Burkhardt, R. Kersevan, M. Lueckhof
CERN, Geneva, Switzerland
F. Collamati
INFN-Roma1, Rome, Italy

The MDISim toolkit is used to evaluate and characterize the beam-gas induced background in the FCC-ee Interaction Region. MDISim allows a full characterization of this beam background source with the locations where the beam-gas scattering occurs as well as the loss points, as a function of different vacuum conditions and composition, for the nominal optics and parameters. Detailed pressure distribution profiles have been obtained running coupled synchrotron radiation and molecular flow montecarlo codes, as an input to the GEANT4 calculations. The particles hitting the pipe in the IR can be tracked in the detectors with a full Geant-4 simulation. Semi-analytic estimates for the expected rates and lifetime are also performed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF085

Export •

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

MOPMK012

Electron Cloud Studies in FCC-ee

electron, collider, simulation, quadrupole

374

E. Belli
Sapienza University of Rome, Rome, Italy
P. Costa Pinto, G. Rumolo, T.F. Sinkovits, M. Taborelli
CERN, Geneva, Switzerland
M. Migliorati
INFN-Roma1, Rome, Italy

Electron cloud effects are one of the most critical aspects for the LHC and the future circular colliders. In the frame of the electron-positron collider FCC-ee, an estimation of the electron cloud build up in the machine will be discussed in this paper. A preliminary evaluation of the heat load in the arc components and interaction region magnets will be presented, together with possible mitigation strategies.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK012

Export •

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

MOPML011

Liquid Cluster Ion Beam Processing of Transition Metal Films

acceleration, radiation, target, experiment

415

D. Shimizu, H. Ryuto, M. Takeuchi, D. Yamamoto
Kyoto University, Photonics and Electronics Science and Engineering Center, Kyoto, Japan

The irradiation effects of cluster ion beams are characterized by the high-density collision of molecules that comprise the clusters against a target. According to molecular dynamics calculations, the local temperature of the colliding cluster and the surface of the target are expected to increase to several thousand K. The enhancement of the chemical interactions between the molecules in the colliding clusters and the atoms on the target surface is expected, if polyatomic molecules, such as ethanol and acetone, are used for the source material of the cluster. So, the irradiation effects of the polyatomic liquid cluster ion beams on transition metal films have been studied to examine the possibility of utilizing the liquid cluster ion beam technique for the processing of transition metal films. The transition metal films were formed by magnetron sputtering. The liquid clusters were produced by the adiabatic expansion method and ionized by electron ionization. The sputtering yields of transition metal films induced by liquid cluster ions are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML011

Export •

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

MOPML029

A Portable X-ray Source Based on Dielectric Accelerators

electron, target, shielding, solenoid

464

C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
S.P. Antipov, A. Kanareykin, R.A. Kostin
Euclid Beamlabs LLC, Bolingbrook, USA

Funding: The work has been supported by the U.S. Department of Homeland Security (DHS), Domestic Nuclear Detection Office (DNDO), under a competitively awarded contract No. HSHQDC-17-C-00007.
The portable low energy accelerator based X-ray sources have attractive applications in the non-destructive examination as a replacement of radiological gamma isotope sources. We are developing an inexpensive ultra-compact dielectric accelerator technology for low energy electron beams. The portability in the realm of this proposal is unprecedented ~ 1 ft3 volume with ~ 50 lbs of weight. The use of ceramics makes the transverse size of the accelerating waveguide comparable to that of a pencil. Because of this size reduction, additional weight reduction of shielding becomes possible. The article will report on the progress of this project.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML029

Export •

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

MOPML062

Accelerator Neutron Source for Boron Neutron Capture Therapy

neutron, proton, experiment, tandem-accelerator

550

S.Yu. Taskaev, D.A. Kasatov, A.N. Makarov, Y.M. Ostreinov, I.M. Shchudlo, I.N. Sorokin
BINP SB RAS, Novosibirsk, Russia
T.A. Bykov
Budker INP & NSU, Novosibirsk, Russia
Ya.A. Kolesnikov, A.M. Koshkarev, E.O. Sokolova
NSU, Novosibirsk, Russia

Funding: This study was carried out with a grant from the Russian Science Foundation (project No. 14-32-00006-P) with the support of the Budker Institute of Nuclear Physics and Novosibirsk State University.
A source of epithermal neutrons based on a vacuum-insulated tandem accelerator and a lithium target is developed for the technique of boron neutron capture therapy. A stationary proton beam of 2 MeV with a current of up to 5 mA was obtained in the accelerator. Neutron generation was performed and the flux and neutron spectrum were experimentally measured. A Beam Shaping Assembly was developed and manufactured, which makes it possible to form a therapeutic beam of neutrons to the greatest extent satisfying the requirements of BNCT. It was established that neutron irradiation of tumor cells of human glioma U251 and human glioblastoma T98G, previously incubated in a medium with boron, led to a significant suppression of their viability. Irradiation of mice with grafted human glioblastoma tumor led to their complete cure. In order to increase the beam parameters, the facility was equipped with a wire scanner OWS-30 (D-Pace, Canada; under the license of TRIUMF), a non-contact current sensor NPTC (Bergos, France), a FLIR T650SC infrared camera, an Optris CT Laser 3ML SF pyrometer (Optris, GmbH, Germany), cooled diaphragms with thermistors, telescopic beam receivers with thermoresistors, a new bushing insulator. Two new sources of negative hydrogen ions with a high current are being prepared, one of them is surface-plasma, the other is voluminous. The investigations established the effect of space charge and spherical aberration of lens on the ion beam transport, the dependence of the heating of the diaphragms of the electrodes and the size of the proton beam on the current of the injected beam of negative hydrogen ions and the pressure of the residual gas in the transport channel. The report describes the modernization of the accelerator, discusses the results of research, declares plans.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML062

Export •

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

MOPML066

Ultrafast Mega-electron-volt Gas-Phase Electron Diffraction at SLAC National Accelerator Laboratory

electron, gun, laser, experiment

556

X. Shen, R.K. Li, X.J. Wang, S.P. Weathersby, J. Yang
SLAC, Menlo Park, California, USA

Funding: This work was supported in part by the U.S. Department of Energy Contract No. DE-AC02-76SF00515, and the SLAC UED/UEM Initiative Program Development Fund.
Ultrashort mega-electron-volt (MeV) electron beams from radio-frequency (rf) photoinjectors have recently attracted strong interests for application in ultrafast gas-phase electron diffraction (UGED). Such high-brightness electron beams are capable of providing 100-fs level temporal resolution and sub-Angstrom level spatial resolution to capture the ultrafast structural dynamics from photoexcited gas molecules. To experimentally demonstrate such an ultrafast electron scattering instrument, a high performance UGED system has been commissioned at SLAC National Accelerator Laboratory. The UGED instrument produces 3.7 MeV electron beams with 2 fC beam charge at 180-Hz repetition rate. The temporal resolution is characterized to be 150 fs full-width-at-half-maximum (FWHM), while the spatial resolution is measured to be 0.76 Å FWHM. The UGED instrument also demonstrates outstanding performance in vacuum, rf, and electron beam pointing stability. Details of the performance of the SLAC MeV UGED system is reported in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML066

Export •

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

TUYGBD2

A Review of DAΦNE Performances During the KLOE-2 Run

luminosity, detector, operation, 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

Export •

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

TUPAF012

Commissioning of the Lipac Medium Energy Beam Transport Line

cavity, rfq, controls, operation

683

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

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

DOI •

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

Export •

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

TUPAF015

Preliminary Test Results of the First ESS Elliptical Cryomodule Demonstrator

cavity, cryomodule, cryogenics, radiation

691

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

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

DOI •

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

Export •

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

TUPAF021

Identification and Removal of SPS Aperture Limitations

optics, target, proton, injection

709

V. Kain, R. Alemany-Fernández, H. Bartosik, S. Cettour Cave, K. Cornelis, P. Cruikshank, J.A. Ferreira Somoza, B. Goddard, C. Pasquino
CERN, Geneva, Switzerland

The CERN SPS (Super Proton Synchrotron) serves as LHC injector and provides beam for the North Area fixed target experiments. Since the 2016 run automated local aperture scans have been performed with the main focus on the vertical plane where limitations typically arise due to the flat vacuum chambers in most SPS elements. For LHC beams the aperture limitations with the present low integer tune optics also occur at locations with large dispersion. Aperture measurements in the horizontal plane using a variety of techniques were performed and showed surprising results, which could partially explain the unexpected losses of high intensity LHC beams at the SPS flat bottom. In this paper, reference measurements from 2016 are compared with the ones taken at the beginning of the run in 2017. Several aperture restrictions in the vertical plane could be found and cured, and a potential systematic restriction in the horizontal plane has been identified. The results of the measurements and the origin of the restrictions are presented in this paper, and the outlook for partial mitigation is discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF021

Export •

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

TUPAF030

Electron Cloud Build Up for LHC Sawtooth Vacuum Chamber

electron, photon, simulation, synchrotron

744

G. Guillermo Cantón, F. Zimmermann
CERN, Geneva, Switzerland
G.H.I. Maury Cuna, E. D. Ocampo
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico

At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. For the arcs of LHC a sawtooth pattern had been imprinted on the horizontally outward side of the vacuum chamber in order to locally absorb synchrotron radiation photons without dispersing them all around the chamber. Using the combination of the codes Synrad3D and PyCLOUD we examine the effect of realistic absorption distributions with and without sawtooth on the build up of electron clouds.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF030

Export •

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

TUPAF037

Validation of the CERN PS Eddy Current Injection Septa

septum, simulation, injection, HOM

768

M. Hourican, B. Balhan, J.C.C.M. Borburgh, T. Masson, A. Sanz Ull
CERN, Geneva, Switzerland

As part of the upgrade of the CERN PS accelerator from 1.4 GeV to 2 GeV, new injection septa have been developed. The system is comprised of a pulsed eddy current septum magnet and a pulsed eddy current bumper magnet. Both magnets will be housed in a common vacuum vessel and powered by independent power converters. In-depth studies and simulations have been performed to reduce as much as possible the leak field by designing specific magnetic shielding, combined with dual function beam impedance shielding. A prototype magnet was built and measured to validate the simulations. The final complete system will be bake-able at 200C and uses demineralised water for cooling. Closed circuit cooling systems have been integrated to reduce risks of vacuum leaks. This report describes the electromechanical design from the concept and simulation stages to the prototyping and final manufacturing. Results of the initial magnetic measurements, including field homogeneity and leak field mitigation methods are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF037

Export •

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

TUPAF049

Analysis of Loss Signatures of Unidentified Falling Objects in the LHC

proton, operation, beam-losses, 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).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF049

Export •

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

TUPAF057

The SPS Tests of the HL-LHC Crab Cavities

cavity, cryomodule, HOM, operation

846

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

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

DOI •

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

Export •

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

TUPAF068

Functional Integration of the RFQ in the ESS Systems

rfq, cavity, controls, LLRF

890

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

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

DOI •

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

Export •

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

TUPAF076

Design of PIP-II Medium Energy Beam Transport

SRF, linac, kicker, cryomodule

905

A. Saini, C.M. Baffes, A.Z. Chen, V.A. Lebedev, L.R. Prost, A.V. Shemyakin
Fermilab, Batavia, Illinois, USA

Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics
The Proton Improvement Plan-II (PIP-II) is a proposed upgrade for the accelerator complex at Fermilab. The central piece of PIP-II is a superconducting radio frequency (SRF) 800 MeV linac capable of operating in both CW and pulse regimes. The PIP-II linac comprises a warm front-end that includes a H⁻ ion source capable of delivering 15-mA, 30-keV DC or pulsed beam, a Low Energy Beam Transport (LEBT), a 162.5 MHz, CW Radio-Frequency Quadrupole (RFQ) accelerating the ions to 2.1 MeV and, a 14-m Medium Energy Beam Transport (MEBT) before beam is injected into SRF part of the linac. This paper presents the PIP-II MEBT design and, discusses operational features and considerations that lead to existing optics design such as bunch by bunch chopping system, minimization of radiation coming to the warm front-end from the SRF linac using a concrete wall, a robust vacuum protection system etc.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF076

Export •

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

TUPAF084

The First-of-Series SIS100 Cryocatcher

cryogenics, site, HOM, instrumentation

930

L.H.J. Bozyk, Sh. Ahmed, P.J. Spiller
GSI, Darmstadt, Germany

The superconducting heavy ion synchrotron SIS100 of the FAIR-facility will be equipped with 60 cryocatcher, to suppress dynamic vacuum effects. A prototype cryocatcher has been designed, manufactured and underwent several tests. The results yielded in the design of the series cryocatcher. Recently, the First-of-Series cryocatcher has been manufactured and tested. Results from the manufacturing process and the site acceptance tests, including cryogenic test with liquid helium are presented. The FoS cryocatcher sucessfully passed all tests and the series production will be released.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF084

Export •

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

TUPAK012

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

cavity, acceleration, operation, power-supply

987

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

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

DOI •

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

Export •

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

TUPAL046

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

rfq, operation, linac, ion-source

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL046

Export •

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

TUPAL055

Progress with Carbon Stripping Foils at ISIS

operation, synchrotron, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL055

Export •

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

TUPAL056

High Order Image Terms and Harmonic Closed Orbits at the ISIS Synchrotron

closed-orbit, simulation, resonance, space-charge

1140

B.G. Pine, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the spallation neutron source at Rutherford Appleton Laboratory in the UK. Protons are accelerated from 70 to 800 MeV in a 50 Hz rapid cycling synchrotron. Due to the intense beam, space charge forces are high during the first part of the acceleration cycle. The vacuum vessel in the synchrotron has a rectangular shape where the apertures are conformal to the design beam envelopes. At high intensities image forces interact with the beam, especially when the closed orbit is large. An analysis of image forces has been made and used to classify higher order image terms. These have been identified using simulations of round beams in rectangular vacuum vessels. The higher order image terms from harmonic closed orbits have been used with single particle resonance theory, taking account of the coherent nature of the beam response. Several predictions of beam resonance have been made. A simulation study has been carried out using a smooth focusing lattice and uniform density beams. Resonant beam behaviour has been observed and explained by the proposed theory.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL056

Export •

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

TUZGBE3

Towards Implementation of Laser Engineered Surface Structures for Electron Cloud Mitigation

electron, laser, operation, 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]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE3

Export •

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

TUPMF007

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

undulator, cryogenics, operation, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF007

Export •

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

TUPMF027

Impedance Modeling for eRHIC

impedance, dipole, quadrupole, electron

1309

A. Blednykh, G. Bassi, M. Blaskiewicz, C. Hetzel, V. Ptitsyn, V.V. Smaluk, F.J. Willeke
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the US DOE under contract number DE-SC0012704
The impedance budget for the eRHIC project is discussed at its earlier stage of development. As a first step, with the eRHIC lattice and beam parameters , we use the geometric impedances of the vacuum chamber components simulated for the NSLS-II project. The impedance budged will be updated next with more impedance data simulated for the optimized eRHIC vacuum components. It will allows us to keep track on the collective effects changes with more realistic components added to the ring.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF027

Export •

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

TUPMF032

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

cavity, electron, GUI, coupling

1316

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

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

DOI •

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

Export •

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

TUPMF040

Alignment of Current Strips at the Canadian Light Source

alignment, closed-orbit, undulator, electron

1342

W.A. Wurtz
CLS, Saskatoon, Saskatchewan, Canada
Q.L. Zhang
SINAP, Shanghai, People's Republic of China

The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source will employ a 180 mm period elliptically polarizing undulator (EPU180), which will have significant impacts on beam dynamics with large tune shifts and reductions in dynamic aperture. Current strips mounted to the vacuum chamber are intended to mitigate the effects of EPU180 with each strip powered by an independent power supply. It is important to accurately model the current strips in order to calculate the required compensation. We model the current strips as straight wires, parallel to the electron beam, with small horizontal and vertical displacements from their nominal positions. As the real current strips are not completely straight, this is an effective model, but justified as we are mostly interested in the magnetic field integrated along the strips. By activating two strips and measuring the ratio of the two currents needed to minimize closed orbit distortion in the horizontal and vertical planes, we can find the effective horizontal and vertical displacements of the straight wires in the model. Our goal is to create an effective model of the strips from beam-based measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF040

Export •

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

TUPMK002

First Tests of the Apple II Undulator for the LOREA Insertion Device and Front End

undulator, simulation, optics, insertion-device

1488

J. Campmany, L.G.O. Garcia-Orta, J. Marcos, Z. Martí, V. Massana, M. Quispe
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

ALBA synchrotron is currently installing the new beamline LOREA (Low-Energy Ultra-High-Resolution Angular Photoemission for Complex Materials at ALBA). It operates in the range of 10 - 1500 eV with polarized light. To produce the light for the beamline, an Apple II undulator with a period of 125 mm has been chosen. It can operate as an undulator at low energies and as a wiggler at high energies, providing a wide energy range. The device was built by KYMA, delivered on February 2017 and installed in August 2017. We present the magnetic measurements made during SAT as well as the simulations of the influence of the ID in the electron beam dynamics and the first measurements with beam. On the other hand, the high demanding characteristics of the beamline lead to a device providing high power and wide beam in some working modes. This situation has been a challenge for the Front End (FE) thermal load. It has been built by the companies RMP and TVP, and the FE modules have been installed in the tunnel along autumn 2017. We present the Site Acceptance Tests results as well as the technical solutions adopted, especially in terms of mechanical design and used materials.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK002

Export •

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

TUPMK010

Differences in Current Dependent Tune Shifts Measured by Direct or ORM Based Methods

storage-ring, impedance, optics, wakefield

1510

Y.E. Tan, R.T. Dowd
AS - ANSTO, Clayton, Australia

The change in the tunes as a function of total beam current is a well documented effect and has been attributed to quadrupole like self induced wakefields. Theoretical models presented by others have utilised direct methods (spectrum analyser) to measure the tunes in the analysis. In this report we shall present observations that show the ORM method, Linear Optics from Closed Optics (LOCO), and direct methods have significantly different tune gradients. The different tune gradients is attributed to the static (ORM) and dynamic (direct) nature of the measurements where in the static case the vacuum chamber is to be considered as a thin wall while in the dynamic case the vacuum chamber wall is to be considered as a thick wall.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK010

Export •

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

TUPML019

Design of Multi-Alkali Photocathode Preparation System for CTFEL Facility

cathode, FEL, laser, electron

1571

D.X. Xiao, M. Li, Q. Pan, H. Wang, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

The first saturated lasing of the China Academy of Engineering Physics tera-hertz free electron laser (CTFEL) facility has been realized. In order to improve the performance of the CTFEL facility, the multi-alkali photocathode with much longer life-time has been proposed to replace the GaAs photocathode currently used. This paper presents the design of the multi-alkali photocathode preparation system, which consists of three chambers: the suitcase chamber, the preparation chamber, and the loading chamber. The function of each chamber is also discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML019

Export •

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

TUPML025

Long Lifetime Spin-Polarized GaAs Photocathode Activated by Cs2Te

cathode, electron, polarization, photon

1589

J. Bae, L. Cultrera, P. Digiacomo
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
I.V. Bazarov
Cornell University, Ithaca, New York, USA

Funding: This work was supported by the Department of Energy Grant Nos. DE-SC0016203 and NSF PHY-1461111.
High intensity and highly spin-polarized electron source is of great interest to the next generation Electron Ion Colliders. GaAs prepared by the standard activation method, which is the most widely used spin-polarized photocathode, is notorious for its vacuum sensitivity and short operational lifetime. To improve the lifetime of GaAs photocathodes, we activated GaAs by Cs2Te, a material well known for its robustness. We confirmed the Cs2Te layer forms negative electron affinity on GaAs with a factor of 5 improvement in lifetime. Furthermore, the new activation method had no adverse effect on spin-polarization. Considering Cs2Te forms much thicker activation layer (~ 2 nm) compared to the standard activation layer (~ monolayer), our results trigger a paradigm shift on new activation methods with other robust materials that were avoided for their thickness.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML025

Export •

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

TUPML073

Ion Source and Low Energy Beam Transport Line Final Commissioning Step and Transfer from INFN to ESS

MMI, proton, ion-source, controls

1712

L. Celona, A. Amato, G. Calabrese, A.C. Caruso, G. Castro, F. Chines, S. Gammino, O. Leonardi, A. Longhitano, G. Manno, S. Marletta, D. Mascali, A. Maugeri, M. Mazzaglia, A. Miraglia, L. Neri, S. Passarello, A. Seminara, D. Siliato, A. Spartà, G. Torrisi
INFN/LNS, Catania, Italy

At the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), the beam commissioning of the high intensity Proton Source for the European Spallation Source (PS-ESS) was completed in November 2017. All requirements have been satisfied and certified by the European Spallation Source (ESS). In the last step of the commissioning a complete characterization of the source has been carried out and some results are hereinafter reported. The shipment of the source was done in December 2017, followed by the installation in January while the beam commissioning is foreseen during summer 2018. The paper describes the final commissioning steps at INFN-LNS, the procedure adopted for a safe transfer of the equipment, the transfer of knowledge needed for the operation and the maintenance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML073

Export •

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

TUPML075

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

target, ion-source, proton, operation

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML075

Export •

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

WEXGBD1

Development of Very Short Period Undulators

undulator, electron, radiation, factory

1735

S. Yamamoto
KEK, Ibaraki, Japan

Scientists and engineers at KEK have developed undulator magnets having very short period lengths. Magnet plates 100mm and 152mm long with 4-mm period length have been successfully fabricated. They produce an undulator field of approximately 4kG at a gap of 1.6mm. The magnetic field characterization shows that the undulator field is satisfactory in quality for a very short period undulator. KEK has recently installed a short-period undulator at a 50-MeV linac and observed a first light, and will soon start an experiment using a short-period undulator with laser-accelerated electrons for future table-top XFELs. This invited talk summarizes the current status, and experimental activities and results related to short-period undulators and table-top FELs.

Slides WEXGBD1 [3.515 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBD1

Export •

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

WEPAF010

Fast Glitch Detection of Coupled Bunch Instabilities and Orbit Motions

feedback, storage-ring, injection, operation

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF010

Export •

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

WEPAF011

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

feedback, operation, emittance, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF011

Export •

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

WEPAF012

Improvements of NSLS-II X-ray Diagnostic Beamlines

emittance, storage-ring, photon, radiation

1837

W.X. Cheng, B. Bacha, B.N. Kosciuk, D. Padrazo Jr
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE contract No: DE-SC0012704
There are two X-ray diagnostic beamlines (XDB) developed at NSLS-II storage ring to measure emittance, energy spread, and other machine parameters. The first beamline utilizes a soft bending magnet radiation has been in operation since 2014. The tungsten pinhole originally located in the air had corrosion issue. The beamline has been improved by extending the vacuum to the imaging system. The second X-ray pinhole beamline using three-pole wiggler (TPW) radiation has been constructed and commissioned recently. Energy spread is able to be precisely measured due to large dispersion at the source point. A gated camera is equipped with the new beamline to acquire profiles within one turn. Recent operation experience and beam measurements will be presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF012

Export •

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

WEPAF049

Energy Beam Position Monitor Button Array Electronics for the European XFEL

electron, FEL, electronics, pick-up

1927

B. Lorbeer, B. Beutner, H.T. Duhme, L. Fröhlich, D. Lipka, D. Nölle
DESY, Hamburg, Germany

The European XFEL(X-Ray Free Electron Laser) at DESY(Deutsches Elektronen-Synchrotron) in Hamburg/Schenefeld started commissioning in early 2017. Before the pulsed electron beam is accelerated to its final energy of 14 GeV, the energy of the bunch can be compressed in three bunch compression chicanes at 130 MeV, 700 MeV and 2400 MeV. The vacuum chamber in these sections is tapered from 40 mm round beam pipe to a 40 cm rectangular shaped vacuum section. A custom made button array type of BPM(Beam position Monitor) is installed in this section with 26 button electrode feed-throughs. The analog and digital readout electronics for this monitor and the first experience with the calibration and operational aspects of this system are presented in this poster.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF049

Export •

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

WEPAF068

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

cavity, target, monitoring, dipole

1986

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

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

DOI •

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

Export •

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

WEPAL014

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

linac, injection, electron, cavity

2177

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

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

DOI •

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

Export •

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

WEPAL058

Beam Loss Studies at the Taiwan Photon Source

radiation, injection, scattering, undulator

2309

C.H. Huang, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu
NSRRC, Hsinchu, Taiwan

PIN-photodiodes and RadFETs are installed in the storage ring of the Taiwan Photon Source (TPS) to study beam loss distributions and mechanisms. In the highest dose area, the radiation comes mainly from hard X-rays produced by synchrotron bending magnets. During beam cleaning and after replacing a vacuum chamber, losses due to inelastic Coulomb scattering occur mostly downstream from bending magnets while elastic scattering causes electrons to get lost mainly after an elliptically polarizing undulator which has a limited vertical aperture. During the injection period, the beam loss pattern can be changed by modifying injection conditions or lattice settings. The beam loss usually happens in the injection section and small-aperture section. The injection efficiency can be improved by minimizing the detected injection loss.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL058

Export •

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

WEPMF004

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

cavity, rfq, linac, interface

2375

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

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

DOI •

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

Export •

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

WEPMF009

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

radiation, niobium, experiment, cavity

2384

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

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

DOI •

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

Export •

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

WEPMF022

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

cavity, simulation, operation, electron

2416

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

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

DOI •

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

Export •

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

WEPMF031

Development of a High-Power High-Directivity Directional Coupler and Four Power Dividers for S-Band

coupling, GUI, MMI, simulation

2422

X. He, J. Lei, J.R. Zhang
IHEP, Beijing, People's Republic of China

A novel Bethe-hole S band directional coupler has been designed based on some structural optimizations, the prototype has been tested with a Directivity of more than 30 dB. The new directional coupler can also hold higher power compared to the old type, which is more useful for the future accelerator applications. Four power dividers using different structures are studied and the best one is chosen for fabrication. The prototype with matching rod in the middle has got qualified microwave cold test results and has been used during the whole microwave commissioning of an accelerating structure, the performance is quite stable.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF031

Export •

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

WEPMF032

Experimental Studies on Secondary Electron Emission Characteristics for Chamber Materials of Accelerators

electron, experiment, detector, neutron

2425

Y. Jiao, Z. Duan, W.B. Liu, Y.D. Liu
IHEP, Beijing, People's Republic of China
Liu. S. Liu
Institute of High Energy Physics (IHEP), People's Republic of China
P.C. Wang
DNSC, Dongguan, People's Republic of China

Funding: National Natural Science Foundation of China (11275221) and Key Laboratory Foundation of Particle Acceleration Physics &Technology (Y5294106TD)
Secondary electron emission (SEE) of surface is origin of multipacting effect which could seriously deteriorate beam quality and even perturb the normal operation of particle accelerators. Experimental measurements on secondary electron yield (SEY) on different materials and coating have been developed in many accelerator laboratory. In fact, the SEY is just one parameter of secondary electron emission characteristics which include spatial and energy distribution of emitted electrons. A novel experimental apparatus was set up in China Spallation Neutron Source (CSNS) and innovative measurement methods were applied to obtain the whole characteristics of SEE. With some traditional accelerator chamber materials such as Cu, Al, TiN, SEY dependence on primary electron energy and beam injection angle, spatial and energy distribution of emitted secondary electrons were achieved with this measurement apparatus. This contribution also tries to give all the experimental results a reasonable theoretical analysis.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF032

Export •

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

WEPMF033

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

cavity, coupling, simulation, klystron

2429

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

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

DOI •

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

Export •

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

WEPMF036

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

cavity, SRF, superconducting-cavity, niobium

2440

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

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

DOI •

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

Export •

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

WEPMF039

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

cavity, niobium, experiment, electron

2451

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

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

DOI •

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

Export •

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

WEPMF055

The REGAE Accelerator Vacuum System

gun, cathode, operation, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF055

Export •

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

WEPMF057

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

operation, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF057

Export •

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

WEPMF066

Fabrication of Split-Section X-band Structure Using Elastic Averaging

alignment, coupling, electron, gun

2521

P. Borchard, S.A. Appert, J.S. Hoh
Dymenso LLC, San Francisco, USA

Conventional accelerator structures are manufactured using axial stacks of cylindrical components which, when brazed together, form the accelerator cell structure. Splitting the accelerator structure into two sections along the beam axis allows for a significant reduction in part count and vacuum joint length. The resultant single and coplanar vacuum joint between the two split sections allows for joining techniques such as electron beam welding or brazing of the parts to form the accelerator vacuum envelope. High precision alignment of the two sections is achieved through an elastic averaging interface coupling where improved accuracy is derived from the averaging of errors over a large number of relatively compliant contacting members. The monoblock split sections allow for highly optimized cooling configurations with enhanced heat removal in high heat flux regions, reducing vacuum wall thermal stresses and enabling higher power operation. This paper describes the engineering and manufacturing of four generations of brazed and electron beam welded X-band accelerator structures at both 9.3 GHz and 11.4 GHz frequencies.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF066

Export •

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

WEPMF068

Inexpensive Brazeless Accelerator Prototype

gun, cavity, operation, electron

2528

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

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

DOI •

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

Export •

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

WEPMF074

High Power Conditioning of X-Band RF Components

operation, 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.

DOI •

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

Export •

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

WEPMF078

Assembly of the DQW Crab Cavity Cryomodule for SPS Test

cavity, cryomodule, controls, alignment

2561

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

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

DOI •

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

Export •

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

WEPMF082

Design and Construction of the CERN PS Booster Charge Exchange Injection Chicane Bumpers

injection, septum, simulation, linac

2575

B. Balhan, C. Baud, J.C.C.M. Borburgh, M. Hourican
CERN, Geneva, Switzerland

In the framework of the LIU project and the connection from LINAC4 to PS Booster, the 160 MeV H⁻ beam will be injected horizontally into the PSB by means of one charge-exchange injection system for each PSB ring. A set of four outside vacuum pulsed dipole magnets (BSW) creating the required injection bump has been designed and built. The dynamic requirements for the bump ramp down determine, to a large extent, the field homogeneity due to the eddy currents induced in the corrugated Inconel vacuum chamber. Magnetic simulations were performed to determine the field harmonics during bump ramp down, and the results subsequently used for the dynamic tracking of the beam during injection. The mechanical design and construction of the magnets will be briefly outlined, and the article will conclude with the magnetic measurements of the magnets. The magnetic performance of the as built magnets will be compared with the simulations and the influence of the vacuum chambers on the magnetic field will be quantified.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF082

Export •

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

WEPMF087

LHC Injectors Upgrade Project: Outlook of the Modifications to the Super Proton Synchrotron (SPS) Vacuum System and Impact on the Operation of the Carbon-Coated Vacuum Chambers

impedance, experiment, proton, extraction

2589

C. Pasquino, G. Bregliozzi, P. Chiggiato, P. Cruikshank, A. Farricker, A. Harrison, J. Perez Espinos, J.A.F. Somoza, M. Taborelli, C. Vollinger
CERN, Geneva, Switzerland

Aiming at doubling the beam intensity and reducing the beam emittance, significant modifications of the LHC and its injector chain will take place during Long Shutdown 2 (LS2), starting from 2019. The LIU project (LHC Injector Upgrade), in the specific, touches Linac4, the Proton Synchrotron Booster (PSB), the Proton Synchrotron (PS), the Super Proton Synchrotron (SPS) as well as the heavy ion chain. During LS2, important changes will take place mainly in the Long Straight Sections of the SPS to host a newly conceived dumping system, upgraded RF cavities and upgraded extraction channels. Additionally, the vacuum chambers of the main bending and focusing magnets as well as vacuum drifts will be coated with amorphous carbon in order to reduce the dynamic pressure effects induced by multipacting. The modifications to the different vacuum sectors will be described in details as well as the impact on operation of amorphous carbon coated sectors that have been already deposited.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF087

Export •

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

WEPMF090

Upgrade of the CMS Experimental Beam Vacuum During LS2

experiment, detector, operation, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF090

Export •

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

WEPMG001

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

simulation, interface, proton, operation

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMG001

Export •

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

WEPMG005

First Beam Test of Laser Engineered Surface Structures (LESS) at Cryogenic Temperature in CERN SPS Accelerator

electron, laser, cryogenics, multipactoring

2616

R. Salemme, V. Baglin, S. Calatroni, P. Chiggiato, B. Di Girolamo, E. Garcia-Tabares Valdivieso, B. Jenninger, L. Prever-Loiri, M. Sitko
CERN, Geneva, Switzerland
A. Abdolvand, S. Wackerow
University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
R. Salemme
ITER Organization, St. Paul lez Durance, France

Electron cloud mitigation is an essential requirement for accelerators of positive particles with high intensity beams to guarantee beam stability and limited heat load in cryogenic systems. Laser Engineered Surface Structures (LESS) are being considered, within the High Luminosity upgrade of the LHC collider at CERN (HL-LHC), as an option to reduce the Secondary Electron Yield (SEY) of the surfaces facing the beam, thus suppressing the elec-tron cloud phenomenon. As part of this study, a 2.2 m long Beam Screen (BS) with LESS has been tested at cryogenic temperature in the COLD bore EXperiment (COLDEX) facility in the SPS accelerator at CERN. In this paper, we describe the manufacturing procedure of the beam screen, the employed laser treatment technique and discuss our first observations in COLDEX confirming electron cloud suppression.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMG005

Export •

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

WEPMK001

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

kicker, injection, operation, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK001

Export •

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

WEPMK002

Longitudinal Impedance Analysis of an Upgraded LHC Injection Kicker Magnet

impedance, kicker, simulation, injection

2628

V. Vlachodimitropoulos, M.J. Barnes, L. Vega Cid, W.J.M. Weterings
CERN, Geneva, Switzerland

Prior to Long Shutdown 1 (LS1) one of the LHC injection kickers (MKIs) occasionally exhibited high temperatures leading to significant turnaround times. After a successful impedance mitigation campaign during LS1, the MKI ferrite yokes have remained below their Curie point and have not limited LHC's availability. However, for HL-LHC operation the MKI yokes are expected to exceed their Curie temperatures after long physics runs. To ensure uninterrupted future HL-LHC operation, a modified beam screen design, relocating some of the heat load to more easily cooled parts, and a suitable cooling system are under development as the current baseline for the HL-LHC upgrade of the MKIs. An upgraded beam screen providing such relocation has been designed, simulated and compared to the existing model. To validate simulations, two longitudinal beam coupling impedance measurement techniques have been used and the results are compared to predictions. The modified beam screen was implemented in an upgraded MKI installed in the LHC during the Year End Technical Stop (YETS) 2017/18.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK002

Export •

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

WEPMK003

An Upgraded LHC Injection Kicker Magnet

kicker, injection, electron, impedance

2632

M.J. Barnes, C. Bracco, G. Bregliozzi, A. Chmielinska, L. Ducimetière, B. Goddard, T. Kramer, H. Neupert, L. Vega Cid, V. Vlachodimitropoulos, W.J.M. Weterings, C. Yin Vallgren
CERN, Geneva, Switzerland
A. Chmielinska
EPFL, Lausanne, Switzerland

Funding: Work supported by the HL-LHC project.
An upgrade of the LHC injection kickers is necessary for HL-LHC to avoid excessive beam induced heating of these magnets: the intensity of the HL-LHC beam will be twice that of LHC. In addition, in the event that it is necessary to exchange an injection kicker magnet, the newly installed kicker magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. Extensive studies have been carried out to identify practical solutions to these problems: these include redistributing a significant portion of the beam induced power deposition to ferrite parts of the kicker magnet which are not at pulsed high voltage and water cooling of these parts. Furthermore a surface coating, to mitigate dynamic vacuum activity, has been selected. The results of these studies, except for water cooling, have been implemented on an upgraded LHC injection kicker magnet: this magnet was installed in the LHC during the 2017-18 Year End Technical Stop. This paper presents the upgrades, including some test and measurement results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK003

Export •

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

WEPMK010

LCLS-II Cryomodules Production at Fermilab

cryomodule, cavity, FEL, controls

2652

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

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

DOI •

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

Export •

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

WEPML014

Tooling Systems for the Assembly and Integration of the SSR1 Cryomodule for PIP-II Project at Fermilab

cavity, cryomodule, solenoid, insertion

2710

D. Passarelli, F. Di Ciocchis, M. Parise, V. Roger
Fermilab, Batavia, Illinois, USA

In this paper we present the assembly strategy and tooling design for the SSR1 cryomodule from the cavity string to the final module. Several challenging aspects were considered to minimize undesired stresses on critical components, to preserve the alignment of cavities and solenoids during final assembly, and ultimately to meet the technical requirements of the PIP-II project at Fermilab.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML014

Export •

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

WEPML015

Preparation and Qualification of Jacketed SSR1 Cavities for String Assembly at Fermilab

cavity, cryomodule, multipactoring, controls

2714

D. Passarelli, P. Berrutti, S.K. Chandrasekaran, J.P. Ozelis, M. Parise, L. Ristori, A.M. Rowe, A.I. Sukhanov
Fermilab, Batavia, Illinois, USA

The qualification of dressed 325 MHz Single Spoke Resonators type 1 (SSR1) to meet technical requirements is an important milestone in the development of the SSR1 cryomodule for the PIP-II Project at Fermilab. This paper reports the procedures and lessons learned in processing and preparing these cavities for horizontal cold testing prior to integration into a cavity string assembly.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML015

Export •

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

WEPML028

NEG Coated Vacuum Chambers and Bake-Out-Concept for the HESR at FAIR

dipole, quadrupole, heavy-ion, storage-ring

2745

H. Jagdfeld, N.B. Bongers, J. Böker, P. Chaumet, F.M. Esser, F. Jordan, F. Klehr, G. Langenberg, D. Prasuhn, L. Semke, R. Tölle
FZJ, Jülich, Germany
A. Mauel, G. Natour, U. Pabst
Forschungszentrum Jülich GmbH, Central Institute of Engineering, Electronics and Analytics, Jülich, Germany

The High-Energy Storage Ring (HESR) is part of the international Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt. Forschungszentrum Jülich (IKP and ZEA-1) is responsible for the design and installation of the HESR. The HESR is designed for antiprotons and heavy ion experiments as well. Therefore the vacuum is required to be 10^-11 mbar or better. To achieve this extreme high vacuum (XHV), NEG coated chambers will be used in combination with common vacuum pumps to reach the needed pumping speed and capacity everywhere in the accelerator ring. For activation of the NEG material a bake-out system will be developed and installed. A bake-out test bench was used for checking the achievable end pressure and developing the bake-out system for the NEG coated chambers of the HESR. The results of the tests and the bake-out concept including the layout of the control system are presented. In addition, the temperature distribution of the dedicated heater jackets inside the dipole and quadrupole magnets are shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML028

Export •

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

WEPML029

Vacuum System of the HESR at FAIR, Status of Tests, Layout and Manufacturing

dipole, kicker, injection, controls

2748

F.M. Esser, N.B. Bongers, J. Böker, P. Chaumet, R. Gebel, R. Greven, S. Hamzic, H. Jagdfeld, F. Klehr, B. Laatsch, G. Langenberg, D. Marschall, A. Mauel, G. Natour, D. Prasuhn, L. Reifferscheidt, M. Schmitt, L. Semke, R. Tölle
FZJ, Jülich, Germany

The Research Center Jülich is leading a consortium being responsible for the design and manufacturing of the High-Energy Storage Ring (HESR) which is part of the FAIR project in Darmstadt, Germany. The HESR is designed for antiprotons within a momentum range of 1.5-15 GeV/c but can also be used for heavy ion experiments. Therefore the vacuum quality is expected to be 10^-11 mbar or better which is a great challenge on the overall vacuum layout as well as on the surface quality of the chambers and beam tubes. Whereas all bent dipole chambers are installed, the manufacturing of the pumping bodies with integrated RF meshes as well as several diagnostic chambers are in the focus of investigation. To validate the intended pumping concept of both the bake-out arc sections and the non-bakable straight sections, final tests at the operational test benches are planned. In parallel, the purchasing of valves and first pumps will be prepared. The actual layout of the HESR vacuum system and its components will be presented as well as the progress of manufacturing of several vacuum chambers. The latest experimental test results will be presented also.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML029

Export •

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

WEPML038

Plasma Window as a Pressure Valve for FAIR

plasma, cathode, experiment, electron

2776

B. F. Bohlender, M. Iberler, J. Jacoby
IAP, Frankfurt am Main, Germany
A. Michel
Goethe Universität Frankfurt, Frankfurt am Main, Germany

Funding: Funded by BMBF, Ref. No: 05P15 RFRBA and HIC for FAIR
This contribution shows the progress in the development of a plasma window at the institute for applied physics at Goethe University Frankfurt. A plasma window* is a membrane free transition between two regions of different pressure, enabling beam transmission from a rough vacuum area (~1 mbar) to a higher pressure (up to 1 bar) region on short length scales. In comparison to differential pumping stages a length reduction by a factor of up to 100 is achievable, while the absence of a solid membrane yields prolonged operation time. The sealing effect is based on the high temperature arc discharge sustained in a cooled copper channel between the pressure regimes. Due to a bulk temperature around 10,000K** the viscosity of the gas is dramatically increased, leading to a slower gas flow, enabling a higher pressure gradient. This contribution will present first results regarding the pressure gradient in dependence of the discharge current and the aperture. Until now, a pressure factor around 100 has been established for well over 50 min. This contribution goes along with the one from Mr. A. Michel, he focuses on the spectroscopic analysis of the arc plasma.
*A. Hershcovitch, J. Appl. Phys., AIP Publishing (1995) 78, 5283
**Y.E. Krasik et al., "Plasma Window Characterization", J. Appl. Phys., AIP Publishing (2007) 101, 053305.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML038

Export •

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

WEPML045

Infrastructure for Superconducting CH-Cavity Preparation at HIM

cavity, linac, SRF, heavy-ion

2796

T. Kürzeder, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, M. Miski-Oglu, E. Riehn
HIM, Mainz, Germany
K. Aulenbacher, R.G. Heine, T. Stengler
IKP, Mainz, Germany
W.A. Barth, S. Yaramyshev
GSI, Darmstadt, Germany
F. Hug
KPH, Mainz, Germany

A superconducting cw LINAC for heavy ions is currently under development at GSI in Darmstadt and HIM in Mainz. This Linac is based on 217 MHz multigap bulk niobium Crossbar H-mode RF-cavities. In order to treat and prepare RF-cavities with such a complex geometry a new cleanroom facility has been already built at the Helmholtz-Institut in Mainz. All tools and machines inside the cleanroom can handle cavities with up to 800 mm in diameter and with up to 1300 mm in length. In its ISO-class 6 and 4 zones, respectively it features a large ultrasonic and conductance rinsing bath, a high pressure rinsing (HPR) cabinet and a vacuum oven. The HPR cabinet has an inside clearance of 1.4 m. The large cavities sit on a rotating table, while the rising wand moves vertically up and down. Due to the crossbar structure of the RF-cavities the HPR device allows for off axis-rinsing in their quadrants. For RF testing a 52 m² (4 m x 13 m) concrete shielded area with sufficient liquid helium and nitrogen supply is located next to the cleanroom and the cryo-module assembly area. We will report on the new SRF infrastructure in Mainz and the commissioning of the new high pressure rinsing cabinet.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML045

Export •

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

WEPML053

Availability of the TiN Coating-Free Ceramic in the STF-type Power Coupler for ILC

electron, SRF, cryomodule, GUI

2819

Y. Yamamoto, E. Kako, T. Matsumoto, S. Michizono, A. Yamamoto
KEK, Ibaraki, Japan
M. Irikura, M. Ishibashi, H. Yasutake
Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan
C. Julie, E. Montesinos
CERN, Geneva, Switzerland

In the Superconducting RF Test Facility (STF) in KEK, the research and development for the power coupler with the TiN coating-free ceramic has been done from 2014. In 2016, the high power test at the test bench was stopped due to the worse vacuum level by the unusual heating around the RF window with the TiN coating-free ceramic and the coaxial tapered section, which was caused by the enormous emission of the secondary electrons from the ceramic. And, the situation was never also changed by the ultrapure water rinsing for the power couplers several times. However, in 2017, the ultrasonic rinsing was done for the power couplers for the first time by the collaboration between KEK and TETD. After that, the situation was drastically improved, and the secondary electron emission almost disappeared even in the higher RF duty. This shows that the TiN coating-free ceramic is the prospective item for the cost reduction in ILC. In this report, the recent result for the power coupler with the TiN coating-free ceramic will be presented in detailed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML053

Export •

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

WEPML057

First Commissioning of Vacuum System of Positron Damping Ring for SuperKEKB

photon, MMI, operation, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML057

Export •

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

WEPML059

Status of the SuperKEKB Vacuum System in the Phase-2 Commissioning

MMI, electron, wiggler, permanent-magnet

2833

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

The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8.0·10³⁵ /cm²/s. 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, several problems were found for the future commissioning, and various countermeasures were taken against these problems during the shutdown period before starting the Phase-2 commissioning. For example, permanent magnets were placed around the beam pipe to suppress the electron cloud effect in the positron ring. Other than these works, new beam pipes for the collision point, the super-conducting final focusing magnets and the positron beam injection region were installed in the main ring. Additional six beam collimators were installed for reducing background noise of the particle detector. Furthermore, the vacuum system for new damping ring for the positron beam was constructed. Reported here will be the present status of the vacuum system of the main ring, and major results of the countermeasures taken prior to the Phase-2 commissioning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML059

Export •

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

WEPML069

Fast Kicker and Pulser R&D for the HEPS on-Axis Injection System

kicker, injection, impedance, simulation

2846

H. Shi, J. Chen, Z. Duan, L. Huo, P. Liu, X.L. Shi, G. Wang, L. Wang, N. Wang
IHEP, Beijing, People's Republic of China

The HEPS plans to adopt on-axis injection scheme because the dynamic aperture of machine is not large enough for off-axis injection for its baseline 7BA lattice design. A sets of super fast kicker and pulser of ±15kV amplitude, 15ns pulse bottom width are needed for bunch spacing of 10ns to minimize perturbation on adjacent bunches. To achieve these requirement, a multifaceted R&D program including the strip-line kicker and HV pulser, was initiated last 2 years. So far, the prototype development of a 750mm long strip-line kicker and a DSRD pulser was completed and the preliminary test results show they can meet the baseline requirement of the HEPS.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML069

Export •

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

WEPML071

Superconducting 16-Pole Wiggler for Beijing Electron-Positron Collider II

wiggler, impedance, collider, positron

2853

M.X. Li, X.J. Bian, F.S. Chen, W. Chen, X.J. Sun, H. Wang, J.L. Wang, N. Wang, M.F. Xu, X.C. Yang
IHEP, Beijing, People's Republic of China

A superconducting 16-pole 2.6T wiggler with period 170mm of The High-Energy Photon Source and the Test Facility Project (HEPS-TF) designed and fabricating in the Institute of High Energy Physics (IHEP) in China is described. This wiggler will be installed in Beijing Electron-Positron Collider II (BEPCII). The main parameters and structure of the wiggler are presented. Besides, some vertical testing results are involved.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML071

Export •

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

WEPML072

Gas Permeability Measurement of Graphene Films

background, experiment, neutron, detector

2856

P.C. Wang, X. Sun
DNSC, Dongguan, People's Republic of China
Liu. S. Liu
Institute of High Energy Physics (IHEP), People's Republic of China
C. Meng, H. Wang, D.H. Zhu
IHEP, Beijing, People's Republic of China

Graphene has extremely high strength and thermal conductivity, which can possibly be used for high-power beam window in accelerator. In this paper, gas permeabilities of different graphene films have been measured by the permeation measurement facility. According to the results, the possibility of the graphene-made beam windows will be discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML072

Export •

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

THXGBD3

Status of the ESRF-Extremely Brilliant Source Project

SRF, operation, 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]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBD3

Export •

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

THXGBF2

Beam Commissioning of the IFMIF EVEDA Very High Power RFQ

rfq, cavity, MMI, operation

2902

E. Fagotti, L. Antoniazzi, L. Bellan, D. Bortolato, M. Comunian, A. Facco, M.G. Giacchini, F. Grespan, M. Montis, A. Palmieri, A. Pisent, F. Scantamburlo
INFN/LNL, Legnaro (PD), Italy
B. Bolzon, N. Chauvin, R. Gobin
CEA/IRFU, Gif-sur-Yvette, France
P. Cara
IFMIF/EVEDA, Rokkasho, Japan
H. Dzitko, D. Gex, A. Jokinen, G. Phillips
F4E, Germany
T. Ebisawa, A. Kasugai, K. Kondo, K. Sakamoto, T. Shinya, M. Sugimoto
QST, Aomori, Japan
R. Heidinger, A. Marqueta, I. Moya
Fusion for Energy, Garching, Germany
P. Mereu
INFN-Torino, Torino, Italy
G. Pruneri
Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy
M. Weber
CIEMAT, Madrid, Spain

IFMIF, the International Fusion Materials Irradiation Facility, is an accelerator-based neutron source that will use Li(d, xn) reactions to generate a flux of neutrons with a broad peak at 14 MeV equivalent to the conditions of the Deuterium-Tritium reactions in a fusion power plant. IFMIF is conceived for fusion materials testing. The IFMIF prototype linear accelerator (LIPAc) is jointly developed by Europe and Japan within the IFMIF EVEDA project: it is composed of an ion source, a LEBT, an RFQ, a MEBT and a SC linac, with a final energy of 9 MeV. The 4-vane Radio Frequency Quadrupole (RFQ), developed by INFN in Italy, will accelerate a 130 mA deuteron beam from 0.1 to 5 MeV in continuous wave, for a beam power of 650 kW. The 9.8 m long 175 MHz cavity is composed of 18 x 0.54 m long modules flanged together and aligned within 0.3 mm tolerance. The RFQ was completed, delivered and assembled at the Rokkasho site and is presently under extended RF tests. The second phase of beam commissioning (up to 2.5 MeV/u) was scheduled to start at the end of 2017. Several unexpected issues and incidents significantly delayed the original program, which is however proceeding step by step toward the full achievement of its goals.

Slides THXGBF2 [5.318 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBF2

Export •

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

THPAF026

Modeling Studies for Synchrotron-Radiation-Induced Electron Production in the Vacuum Chamber Walls at CesrTA

photon, electron, simulation, site

3011

S. Poprocki, J.A. Crittenden, D. L. Rubin, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467 and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
We report on calculations of electron production by synchrotron radiation absorbed in the vacuum chamber walls of the Cornell Electron Storage Ring (CESR). These electrons are the source of electron clouds which limit the performance of storage rings by causing betatron tune shifts, instabilities and emittance growth. Until now, cloud buildup modeling codes have used ad hoc models of the production of the seed electrons. We have employed the photon scattering code Synrad3D to quantify the pattern of absorbed photons around the CESR ring, including the transverse distribution on the wall of the beam-pipe. These distributions in absorbed photon energy and incident angle are used as input to Geant4-based simulations of electron emission from the walls. The average quantum efficiency is found to vary dramatically with the location of the absorption site, owing to the distribution in impact energies and angles. The electron production energy spectrum plays an important role in the modeling of electron cloud buildup, where the interplay of production energy and acceleration by the beam bunches determines the time structure and multipacting characteristics of the cloud.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF026

Export •

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

THPAF036

Longitudinal and Quadrupolar Coupling Impedance of an Elliptical Vacuum Chamber With Finite Conductivity in Terms of Mathieu Functions

impedance, coupling, factory, electromagnetic-fields

3040

M. Migliorati, L. Palumbo
Sapienza University of Rome, Rome, Italy
N. Biancacci
CERN, Geneva, Switzerland
M. Migliorati, L. Palumbo
INFN-Roma1, Rome, Italy
V.G. Vaccaro
Naples University Federico II and INFN, Napoli, Italy

Funding: Work supported by the CERN PS-LIU project
The resistive wall impedance of an elliptical vacuum chamber in the classical regime with infinite thickness is known analytically for ultra-relativistic beams by means of the Yokoya form factors. Starting from the longitudinal electric field of a point charge moving at arbitrary speed in an elliptical vacuum chamber, which we express in terms of Mathieu functions, in this paper we take into account the finite conductivity of the beam pipe walls and evaluate the longitudinal and quadrupolar impedance for any beam velocity. We also obtain that the quadrupolar impedance of a circular pipe is different from zero, approaching zero only for ultra-relativistic particles. Even if some of the results, in particular in the ultra-relativistic limit, are already known and expressed in terms of form factors, this approach is the first step towards the calculation of the general problem of a multi-layer vacuum chamber with different conductivities and of elliptic cross section.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF036

Export •

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

THPAF052

Impedance Analysis of New PS Internal Dump Design

impedance, HOM, coupling, resonance

3083

B.K. Popovic, L. Teofili, C. Vollinger
CERN, Geneva, Switzerland

The High Luminosity Large Hadron Collider (HL-LHC) project at CERN calls for increasing beam intensity in the injector chain. In the Proton Synchrotron (PS), a pre-injector of the LHC, these intensities can result in beam instabilities and potential RF heating of machine components, such that impedance mitigation measures are required. To study these intensity effects, the PS impedance model has been developed and is continuously updated. Each new machine element that is to be added into the accelerator requires an impedance study to minimize its contribution with respect to the machine's overall impedance budget. In such a context, this paper presents the impedance analysis of the new design of the internal beam dump for the PS, showing the design process required to reduce the impedance contribution of this element. Furthermore, the impedance analysis of the currently installed beam dump is analysed in order to compare the impedance contributions of the two designs.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF052

Export •

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

THPAK001

Impedance Evaluation of In-Vacuum Undulator at KEK Photon Factory

impedance, simulation, undulator, factory

3200

O. Tanaka, M. Adachi, R. Kato, N. Nakamura, T. Obina, S. Sakanaka, R. Takai, K. Tsuchiya, N. Yamamoto
KEK, Ibaraki, Japan

The estimate of impedance and kick factors of the recently installed at KEK Photon Factory (PF) four In-Vacuum Undulators (IVU) is currently a very important issue, because they could be considerable contributors to the total impedance of PF. Moreover, the coupling impedance of the IVUs could lead to the beam energy loss, changes in the bunch shape, betatron tune shifts and, finally, to the various beam instabilities. Using the simulation tool (CST Particle Studio), longitudinal and transverse impedances of the IVUs were evaluated and compared to analytical formulas and measurement results. The study provides guidelines for mitigation of unwanted impedance, for the accurate estimate of its effects on the beam quality and beam instabilities and also for the impedance budget of a newly designed next-generation machine which has many IVUs and small-aperture beam pipes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK001

Export •

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

THPAK005

Measuring the Coupling Impedance of Vacuum Components for the Advanced Photon Source Upgrade Using a Goubau Line

impedance, cavity, simulation, coupling

3211

M.P. Sangroula
IIT, Chicago, Illinois, USA
R.M. Lill, R.R. Lindberg, R.B. Zabel
ANL, Argonne, Illinois, USA

The Planned upgrade of the Advanced Photon Source to a multi-bend achromat (MBA) will increase the x-ray brightness by two to three orders of magnitude. Storing such an intense beam stably inside the narrow gap vacuum chambers requires sophisticated and appropriately designed rf-components that helps to minimize rf heating and collective instabilities associated with the impedance of these small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. In this paper, we briefly introduce the novel Goubau line (G-line) test fixture for the impedance measurement, at first, and then present our measurements data along with simulations with simulations for various vacuum components designed for the APS Upgrade.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK005

Export •

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

THPAK030

Studies of Longitudinal Dynamics in the Micro-Bunching Instability Using Machine Learning

longitudinal-dynamics, bunching, synchrotron, simulation

3277

T. Boltz, M. Brosi, E. Bründermann, A.-S. Müller, P. Schönfeldt, M. Yan
KIT, Karlsruhe, Germany
M. Schwarz
CERN, Geneva, Switzerland

The operation of synchrotron light sources with short electron bunches increases the emitted CSR power in the THz frequency range. However, the spatial compression leads to complex longitudinal dynamics, causing the formation of micro-structures in the longitudinal bunch profiles. The fast temporal variation and small scale of these micro-structures put challenging demands on their observation. At the KIT storage ring KARA (KArlsruhe Research Accelerator), diagnostics have been developed allowing direct observation of the dynamics by an electro-optical setup, and indirect observation by measuring the fluctuation of the emitted CSR. In this contribution, we present studies of the micro-structure dynamics on simulated data, obtained using the numerical Vlasov-Fokker-Planck solver Inovesa, and first applications on measured data. To deal with generated data sets in the order of terabytes in size, we apply the machine learning technique k-means to identify the dominant micro-structures in the longitudinal bunch profiles. Following this approach, new insights on the correlation of the CSR power fluctuation to the underlying longitudinal dynamics can be gained.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK030

Export •

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

THPAK046

The Ion-Hose Instability in High-Current Multi-Pulse Induction Linacs

electron, simulation, induction, experiment

3320

C. Ekdahl
LANL, Los Alamos, New Mexico, USA

The ion-hose instability has long been considered a danger for long-pulse, high-current electron linear induction accelerators (LIAs)*. This instability is enabled by beam-electron ionization of residual background gas in the accelerator. The space-charge of the high-energy beam ejects low-energy electrons from the ionized channel, leaving a positively-charged ion channel that attracts the electron beam. The beam can oscillate in the potential well around the channel position. Likewise, the electron beam attracts the ions, which can oscillate about the beam position. Because of the vast differences in particle mass, the oscillations are out of phase, and the amplitudes grow unstably. The number of instability e-foldings is proportional to the channel ion density*, which in turn is proportional to the background pressure and pulse length. This scaling of the instability growth was demonstrated on the long-pulse DARHT-II linear induction accelerator (LIA) at Los Alamos**. The ion-hose instability is also problematic for high-current multi-pulse LIAs, because ion recombination times are so very long at typical background pressures. Moreover, because of low ion channel ion densities, and massive ions, channel expansion is too slow to reduce the instability growth by very much. In particular, the ion channel is expected to persist and its density to increase during the 3-microsecond duration of a four-pulse burst from the 2-kA, 20-MeV Scorpius LIA now being developed. Recent simulations with an experimentally validated code that was used to predict DARHT-II growth rates have shown that the magnetic focusing field designed for Scorpius will be strong enough to inhibit ion-hose instability if the background pressure is kept below a value that is readily attainable with the present designs of induction cells and other accelerator components. Details and results of these calculations are the subject of this presentation.
*H. L. Buchanan, Phys. Fluids, vol. 30, pp. 221 - 231, 1987
**C. A. Ekdahl, et al., IEEE Trans. Plasma Sci., vol. 34, pp. 460-466, 2006

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK046

Export •

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

THPAK052

Single Bunch Instabilities in FCC-ee

impedance, collider, simulation, electron

3336

E. Belli
Sapienza University of Rome, Rome, Italy
G. Castorina, M. Migliorati
INFN-Roma1, Rome, Italy
G. Rumolo
CERN, Geneva, Switzerland
B. Spataro, M. Zobov
INFN/LNF, Frascati (Roma), Italy

FCC-ee is a high luminosity lepton collider with a centre-of-mass energy from 91 to 365 GeV. Due to the machine parameters and pipe dimensions, collective effects due to electromagnetic fields produced by the interaction of the beam with the vacuum chamber can be one of the main limitations to the machine performance. In this frame, an impedance model is required to analyze these instabilities and to find possible solutions for their mitigation. This paper will present the contributions of specific machine components to the total impedance budget and their effects on the beam stability. Single bunch instability thresholds will be estimated in both transverse and longitudinal planes.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK052

Export •

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

THPAK077

Feasibility of Non-Metal Vacuum Chamber for Storage Rings

impedance, cavity, insertion-device, insertion

3411

T.-Y. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

This paper studies if the vacuum chamber of an elec-tron storage ring can be made of dielectric non-meta materials such as ceramics or glass. The purpose of this study is to substantially reduce the broadband imped-ance of the vacuum chamber and consequently mitigate single bunch instabilities. This theoretical study examines how these materials can reduce the impedance and pro-poses how to resolve technical problems to occur.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK077

Export •

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

THPAK091

Design of the New Proton Synchrotron Booster Absorber Scraper (PSBAS) in the Framework of the Large Hadron Collider Injection Upgrade (LIU) Project

impedance, proton, simulation, booster

3444

L. Teofili, M. Migliorati
Sapienza University of Rome, Rome, Italy
J.A. Briz Monago, M. Calviani, N. Chritin, J.J. Esala, S.S. Gilardoni, I. Lamas Garcia, J. Maestre, T. Polzin, T.L. Rijoff
CERN, Geneva, Switzerland
T.L. Rijoff
TU Darmstadt, Darmstadt, Germany

The Large Hadron Collider (LHC) Injector Upgrade (LIU)Project at CERN calls for increasing beam intensity for the LHC accelerator chain. Some machine components will not survive the new beam characteristics and need to be rebuilt for the new challenging scenario. This is particularly true for beam intercepting devices (BIDs) such as dumps, collimators, and absorber/scrapers, which are directly exposed to beam impacts. In this context, this work summarizes conceptual design studies on the new Proton Synchrotron Booster (PSB) Absorber/Scraper (PSBAS), a device aimed at cleaning the beam halo at the very early stage of the PSB acceleration. This paper outlines the steps performed to fulfil the component design requirements. It discusses thermo-mechanical effects as a consequence of the beam-matter collisions, simulated with the FLUKA Monte Carlo code and ANSYS finite element software; and the impedance minimization study performed to prevent beam instabilities and to reduce RF-heating on the device.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK091

Export •

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

THPAK103

Pragmatic Method of Deducing a Wake Function for a General 3D Structure

impedance, wakefield, simulation, resonance

3469

G. Skripka
CERN, Geneva, Switzerland
R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

A key quantity in simulating collective beam instabilities is the wake potential of a bunch of particles whose charge distribution is continuously evolving in time. However, obtaining such wake potential is only possible if a wake excited by a single particle in the surrounding environment is known. A practical self-consistent approach was developed to obtain an effective wake function from a numerical wake potential computed for a finite length bunch. The wake potential is processed to a numerical impedance which is decomposed into a set of well-known analytical wake functions. The decomposed impedance is then transformed back into time domain and, thus, converted into an effective wake function which is by nature physical and most consistent with the numerical wake potential. Though the method is limited by the initial numerical impedance data and the choice of impedance decomposition, the retrieved wake function can be used in instability simulations with a bunch whose length is comparable to that used in the electromagnetic field solver. We show that the method can be applied to a general 3D structure, which allows finding effective wake functions of realistic vacuum chambers.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK103

Export •

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

THPAK107

Space-Charge Hamiltonian with a Space Coordinate as Independent Variable

plasma, space-charge, TRIUMF, synchrotron

3484

T. Planche, P. M. Jung, S.D. Rädel
TRIUMF, Vancouver, Canada

We present a version of the Low Lagrangian tailored to treat space-charge effects in particle accelerators: the Lagrangian is relativistic and uses a space coordinate as the independent variable. From this Lagrangian we obtain the corresponding Hamiltonian. From the Hamiltonian we obtain equations of motion for the 8 canonical variables, which can be plugged into a symplectic numerical integrator. We will finally discuss the possibility of numerically solving this problem using an explicit symplectic integrator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK107

Export •

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

THPAL016

Study of the Performances of a 3D Printed BPM

HOM, impedance, instrumentation, status

3656

N. Delerue, D. Auguste, J. Bonis, F. Gauthier, A. Gonnin, S. Jenzer, O. Trofimiuk
LAL, Orsay, France
A. Vion
BV Proto, Sévenans, France

Funding: Work supported by IN2P3 ‘‘3D Metal'' innovation program; Oleh Trofimiuk stay in France is supported by the IDEATE International Associated Laboratory (LIA) between France and Ukraine.
Following previous results which have shown that some components built using additive manufacturing (3D printing) are compatible with ultra high vacuum, we have adapted the design of a stripline BPM to the requirements of additive manufacturing and built it. We report here on the design adaptation and on its mechanical and electrical performances.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL016

Export •

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

THPAL040

Lossy Beam Pipe HOM Load Ceramics with DC Conductivity

experiment, HOM, site, controls

3729

M.L. Neubauer, A. Dudas
Muons, Inc, Illinois, USA
F. Marhauser
JLab, Newport News, Virginia, USA

The ceramic materials used in the beam pipe for super-conducting RF accelerators have the problem of charging due to the electron cloud and secondary electron emission. A novel solution is in the application of conductive nanoparticles to the lossy ceramic. The lossy ceramic is pre-processed to provide for pores that will accept the conductive nanoparticles and then coated with a thin film to prevent the nanoparticles from entering the environment. The same process was also done with sub-micron carbon particles. Measurements of surface conductivity with and without a vacuum compatible sealant are reported on along with microwave measurements.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL040

Export •

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

THPAL052

Finite Element Analysis on Beam-Induced Heat Load in in-Vacuum Undulators with a Small Magnet Gap

undulator, simulation, synchrotron, synchrotron-radiation

3760

J.-C. Chang, Y.-H. Liu
NSRRC, Hsinchu, Taiwan

In-vacuum undulators with a small gap and short period have been applied in synchrotron accelerators for hard X-rays users for years. However, beam-induced heat load resulted from synchrotron radiation or the image current will not only degrade the performance of undulator but damage the magnet foil. It is difficult to quantitatively study heat transfer phenomenon of the magnet foil through physical experiment. In this study, finite element analysis was applied to study the effect of beam-induced heat load on an in-vacuum undulator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL052

Export •

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

THPAL056

Vibration Measurements in the TPS Vacuum System

radiation, synchrotron, storage-ring, synchrotron-radiation

3772

Y.C. Yang, C.K. Chan, C.-C. Chang, C.S. Chen, J. -Y. Chuang, Y.M. Hsiao, C.C. Liang, Y.Z. Lin
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is currently operated in top-up mode for users. In order to improve the stability of the synchrotron light source, vibrations related to the vacuum system have been investigated and improved by turning off pumping systems and reducing the flow rate in chamber cooling water circuits. In this paper, vibrations in different vacuum chambers with normal cooling water condition were investigated, their sources were recorded and clarified and properties of different materials for water tubes were also compared.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL056

Export •

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

THPAL057

Development of the Aluminum Beam Duct for the Ultra-Low Emittance Light Source

experiment, storage-ring, impedance, emittance

3775

G.-Y. Hsiung, J.-R. Chen, C.M. Cheng, S-N. Hsu, H.P. Hsueh, Y.C. Yang
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

The future light source with ultra-low emittance, typically < 500 pm rad, requests the beam duct with inner aperture < 20 mm for the electron storage ring. Besides, the cross section of the beam duct must be kept smooth for lowering the impedance. The aluminum extruded beam duct of 10 mm inside and 1 ~ 2 m in length was developed for this purpose. The beam duct was machined in ethanol to obtain a clean surface for a lower thermal outgassing rate. To mitigate the impedance of the flange connection, a special designed diamond-edge gasket and the aluminum flange without knife edge were developed. The inner diameters of both flange and gasket, 10 mm, are the same as that of beam duct. The sealing of the gasket has been proved leak-tight. The ultimate pressure and the thermal outgassing rate of the beam duct has achieved < 2.0·10^-10 Torr and < 1.4·10^-13 Torr l/(s cm²), respectively after baking. Those results fulfill both the ultrahigh vacuum and lowest impedance are applicable for the next generation ultra-low emittance light source.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL057

Export •

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

THPAL058

Effect of Ozonated Water Cleaning on Photon Stimulated Desorption in a Stainless Steel Chamber

photon, ECR, experiment, radiation

3778

C.M. Cheng, C.K. Chan, C.-C. Chang, Y.T. Cheng, J. -Y. Chuang, G.-Y. Hsiung, L.H. Wu, Y.C. Yang
NSRRC, Hsinchu, Taiwan

Aluminium vacuum chambers cleaned with ozonated water show a reduction of residual carbon and lower surface outgassing rate after baking. We would like to investigate if stainless steel chambers show similar ef-fects. A stainless steel test chamber was cleaned by stand-ard chemical cleaning only and then compared with an-other one after immersion in 30ppm ozonated water for thirty minutes. Both samples were baked, then photon exposed and the photon desorption yields were deter-mined by vacuum gauges and residual gas analysers at the TLS 19B beamline. The test results on photon stimulated desorption yields and partial pressure variations with and without ozonated water cleaning of the stainless steel tubes will be discussed in some detail.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL058

Export •

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

THPAL063

RF and Thermo-Mechanical Considerations in Designing the Waveguide Iris Coupler for the Drift Tube Linac in the ORNL Spallation Neutron Source

cavity, GUI, DTL, simulation

3796

S.W. Lee, Y.W. Kang
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT Battelle, LLC, under contract DE AC05 00OR22725 for the U.S.DOE
The Spallation Neutron Source (SNS) employs tapered ridge waveguide iris couplers to power six drift tube linac (DTL) cavity structures with pulsed RF systems using 2.5MW klystrons at 402.5MHz. All DTL iris couplers have been operating continuously for more than a decade without replacement. Transferring high RF energy to the cavities requires robust RF and mechanical performances with respect to power dissipation, electrical breakdown, and vacuum pressure. Considering the upcoming full 1.4MW operation and the future proton power upgrade (PPU) project, the structural design and the material selection needed to be reviewed for potential spare manufacturing. The existing design and the modified design with improvements to the coupler have been numerically studied. For the study, 3D models were used for RF and structural characterizations of the waveguide iris couplers on the DTL cavity. RF and thermo-mechanical co-simulations were performed to assess the effects of using the different materials and the structural modification.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL063

Export •

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

THPAL069

Simulation of a 10 mm Diameter Cascaded Plasma Window

plasma, cathode, simulation, experiment

3812

P.P. Gan, S. Huang, Y.R. Lu, S.Z. Wang, K. Zhu
PKU, Beijing, People's Republic of China

As a windowless vacuum device, the 10 mm diameter 60 mm long plasma window designed by Peking University only achieved to separate 28.8 kPa from 360 Pa experimentally with 50 A direct current and 2.5 kW power. Based on our 10 mm diameter plasma window, we have proposed a cascaded plasma window to achieve the isolation of atmosphere and high vacuum. In this paper, a numerical 2D FLUENT-based magneto-hydrodynamic simulation on 10 mm diameter cascaded plasma window was developed. The gas inlet, arc creation and plasma expansion segments are all contained in this model. A set of parameters including pressure, temperature, velocity and current distribution were obtained and analysed. In our first simulation, the isolation of 100 kPa and 50 Pa pressure has been realised, and some interesting phenomena occurred.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL069

Export •

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

THPAL076

Experimental Methods for the Assessment of NEG Pumps Working in Dust-Sensitive Environments

cavity, SRF, experiment, background

3828

T. Porcelli, E. Maccallini, P. Manini, M. Mura, M.F. Urbano
SAES Getters S.p.A., Lainate, Italy

NEG pumps have been widely adopted by many accelerator facilities since decades. However, their use in dust-sensitive areas - such as superconductive radio frequency (SRF) cavities - has always been limited by concerns about accidental dust emission, which could induce detrimental field emission. As future machines will necessarily rely on highly-efficient SRF cavities, able to supply very high accelerating gradients, requirements in terms of particle release from vacuum components (e.g., pumps and valves) are becoming more and more stringent. At the same time, achieving stable ultra-high vacuum conditions is crucial, as condensed residual gas might also be a potential source of field emission. At present, a unified standard procedure to assess dust generation and propagation along a machine is still missing and discussions are ongoing in the vacuum community. Recent experimental measurements demonstrated the compatibility of sintered NEG pumps with ultra-clean environments, due to their intrinsic very low dust release. In parallel, in-situ tests performed at different accelerator facilities showed absence of dust contamination from NEGs and no impact on cavities efficiency.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL076

Export •

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

THPAL078

In-Vacuum Lambertson Septum for SPEAR3 Low Emittance Injection

septum, simulation, storage-ring, injection

3831

M.A.G. Johansson, J. Langton, J.A. Safranek
SLAC, Menlo Park, California, USA
S.C. Gottschalk
STI Magnetics LLC, Woodinville, USA

Funding: Work supported by DOE Contract No. DE-AC02-76SF00515
A new in-vacuum Lambertson septum magnet is being designed for the SPEAR3 storage ring, intended to replace the existing septum to allow injection into a new lower emittance operation mode for SPEAR3. The new septum design is constrained to fit in the same length and have the same bend angle as the existing injection septum, so as to minimize changes to surrounding storage ring and transfer line components, while also meeting stringent requirements on the stored beam leakage field. This has led to a design using Vanadium Permendur alloy for the septum pole pieces, with shaping of the inner profile of the stored beam channel to minimize the leakage fields indicated in 2D and 3D magnetic simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL078

Export •

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

THPAL085

High Power RF Conditioning on CLARA

cavity, linac, solenoid, multipactoring

3852

L.S. Cowie, D.J. Scott
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, W.L. Millar
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

The CLARA accelerator at Daresbury Laboratory will have 8 normal conducting RF cavities. Automating the high power RF conditioning of these cavities will mean a repeatable, research-lead process is followed. An auto-mated algorithm has been written in Python. A prototype algorithm was used to condition the first CLARA travel-ling wave linac in October 2017. The linac was success-fully conditioned over approximately 12 million pulses up to 27 MW for a 750 ns pulse. A more complex and robust algorithm was used to re-condition the standing wave 10 Hz photoinjector after a cathode change. The photoinjec-tor was conditioned to 10 MW for a 2.5 μs pulse in Feb-ruary 2018 over 2.1 million pulses. Conditioning method; differences for travelling and standing wave structures; difficulties and interesting phenomena are all discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL085

Export •

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

THPAL086

Superconducting Thin Film RF Measurements

cavity, SRF, niobium, operation

3856

P. Goudket, L. Bizel-Bizellot, L. Gurran, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt, L. Gurran
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Goudket, T. Junginger, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom
L. Gurran, T. Junginger
Lancaster University, Lancaster, United Kingdom

As part of an ongoing programme of SRF Thin Films development, a radiofrequency (RF) cavity and cryostat dedicated to the measurement of superconducting coatings at GHz frequencies was designed to evaluate surface resistive losses on a flat sample. The resonator has now been used for measurements on Thin Film samples. Results from a test on a sample previously tested at Cornell University are presented. In order to simplify the measurements and achieve a faster turnaround, the experiment will be moved to a new cryostat fitted with a cryocooler. This will limit the measurements to low power only, but will allow a much faster sorting of samples to identify those that would benefit from further investigation. A description of the system and initial results will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL086

Export •

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

THPAL092

Test Particle Monte Carlo Simulation of NEG Coated Narrow Tubular Samples

ECR, experiment, simulation, SRF

3862

O. Seify, A.N. Hannah, O.B. Malyshev, Sirvinskaite, R. Sirvinskaite, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
Sirvinskaite, R. Sirvinskaite
Loughborough University, Loughborough, Leicestershire, United Kingdom

The pumping properties of the NEG coated vacuum chambers play an important role in the efficiency of vac-uum system of accelerators. The sticking probability of the NEG films is one the most important parameters to characterise the pumping properties of the NEG coated vacuum chambers. In order to investigate the NEG film sticking probability, Test Particle Monte-Carlo (TPMC) models were used. The models were based on the design of the installed experimental setup in ASTeC Vacuum Science group laboratory at Daresbury Laboratory (DL). The results of the simulations have been used for inter-preting the results of the measurements in the experi-mental setup.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL092

Export •

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

THPAL098

Pumping Properties of Single Metal Zirconium Non-Evaporable Getter Coating

target, site, experiment, injection

3869

Sirvinskaite, R. Sirvinskaite, M.D. Cropper, M.D. Cropper
Loughborough University, Loughborough, Leicestershire, United Kingdom
A.N. Hannah, O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
O.B. Malyshev, R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Non-evaporable getter (NEG) coating has been used for years in many particle accelerator facilities due to its evenly distributed pumping speed, low thermal outgassing, and low photon and electron stimulated desorption yields. We have previously demonstrated that quaternary Ti-Zr-Hf-V coating deposited from an alloy wire has the lowest desorption yields, the highest sticking probability and sorption capacity. In this work, we explore the single element targets which are widely available and can be produced in a form of a wire that is easy to apply for a uniform coating of various shapes of vacuum chamber. Single metal Zr coatings have been tested to find a more efficient and cheaper way of producing the NEG-coated vacuum chambers. Two samples coated with Zr of dense and columnar structure were analysed and results of the pumping properties are reported. The results show that pure Zr coating could be an economic solution, despite not being as effective as can be achieved with quaternary NEG film. It shows that columnar Zr coating can be activated and reaches full pumping capacity at 160°C. This is close to the activation temperature of Ti-Zr-Hf-V and lower than that for the widely used ternary Ti-Zr-V alloy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL098

Export •

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

THPAL104

The Magnetic Field Measurement Systems for a Cryogenic Undulator and a Superconducting Undulator at SSRF

cryogenics, SRF, undulator, GUI

3878

H.F. Wang
SSRF, Shanghai, People's Republic of China
M.F. Qian, W. Zhang, Q.G. Zhou
SINAP, Shanghai, People's Republic of China

Two cryogenic permanent magnet undulators (CPMU) have been developed and assembled into storage ring at SSRF，in order to reach larger magnetic field and to produce higher brilliance in the hard X rays domain. Lowering the temperature of permanent magnets increases the magnetic produced field about by 15%. A set of magnetic measurement system and a suitable magnetic field optimization method have been developed. The design of a magnetic measurement bench based on a Hall probe to perform low temperature measurement has been finished. In addition, a 50-period superconducting undulator prototype with 16mm period length is also being developed for more photons with some specific photon characteristic. And a special hall probe system has been built in order to characterize the magnetic field distribution of the SCU prototype.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL104

Export •

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

THPAL106

Heating Unit Controller at NSRC SOLARIS

TANGO, controls, undulator, PLC

3885

W.T. Kitka, P. Bulira, P. Czernecki, M.K. Fa'owski, K. Kubal, P. Kurdziel, A.M. Marendziak, M.P. Nowak, M. Ostoja-Gajewski, M. Rozwadowski, K. Wawrzyniak, Z. Zbylut
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland

Solaris is a third generation light source constructed at the Jagiellonian University in Kraków, Poland. The machine was designed by the MAX IV Laboratory team. Commissioning of the machine was accomplished at 2016 April and now synchrotron operate in decay mode. Two beamlines PEEM/XAS and UARPES were installed and now are being commissioned. Three more PHELIX, XMCD and diagnostic beamline have received funding and it will be installed and commissioned in range of next few years. The SOLARIS Heating Unit Controller (HUC) was designed to perform bake-out process of new installed vacuum systems. It will allow to perform activation process of undulator vacuum chamber inner coated with NEG layer and also activation process of NEG strips installed in dipole vacuum chambers. HUC is able to control independently up to six 2 kW temperature channels and two current channels. System was built based on Allen-Bradley PLC and Tango Controls. Easy access to the device is provided by the GUI design based on Taurus framework.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL106

Export •

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

THPAL107

Three Years of Operational Experience With the Solaris Vacuum System

storage-ring, electron, MMI, synchrotron

3888

A.M. Marendziak, M. Rozwadowski, T. Sobol, M.J. Stankiewicz, A.I. Wawrzyniak
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland

Solaris, a 1.5 GeV third generation synchrotron light source, was commissioned in 2016 April and is currently operated in decay mode. Two beamlines PEEM/XAS and UARPES were installed and now are being commis-sioned. Three more PHELIX, XMCD and diagnostic beamlines have received funding and will be installed and commissioned in next few years. With total accumu-lated beam dose near to 690 A.h and three orders of mag-nitude reduction of outgassing the design goal of 500 mA beam current and electron energy of 1.5 GeV has been achieved. As the beam current was increased, a few vacu-um problems were encountered, including vacuum leaks in RF and arc sectors and unexpected pressure bursts near photon absorbers. Lessons learned and operational expe-rience will be presented and discussed in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL107

Export •

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

THPAL110

High-Power RF Test of Coaxial Couplers for the Injection Linac of XiPAF

cavity, multipactoring, coupling, linac

3899

Y. Lei, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, H.Y. Zhang, S.X. Zheng
TUB, Beijing, People's Republic of China
J. Jiang, H. Li, C. Yu
Beijing Aerospace Guagntong Technology Co., Beijing, People's Republic of China

For the high-power RF test of the coaxial couplers which will be employed on the linac injector of the XiPAF (Xi'an Proton Application Facility) project, a high-power conditioning cavity was designed and manufactured [1]. There are some optimized aspects on the cavity and couplers to obtain better RF performance during the high-power testing process. The traveling-wave test and full-power-reflection test were executed to check whether the coupler can afford the enough power level for the linac operation, and whether only one coupler can afford the total power for the RFQ. The construction of the testing stand, optimization of RF parameters and results of high-power RF test are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL110

Export •

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

THPAL114

The Analytical Model of the Helical Accelerating Structure of Linac with Helix Outside of the Vacuum Chamber

experiment, simulation, resonance, TRIUMF

3908

N.V. Avreline
TRIUMF, Vancouver, Canada

An analytical model of the helical RF resonator for the single charged 250 keV nitrogen ion implanter operating in CW was developed. The analytical model allowed to determine the geometry of the accelerating structure and to construct CST Microwave Studio and ANSYS HFSS models based on this analytical model. Results obtained from the analytical model and simulations were within 5% of each other. The experimental investigation of the accelerating section confirmed that the models are correct. The accelerating section was tuned and verified for the right accelerating field distribution and operating frequency. Finally, the section was successfully tested in 2 kW CW RF power.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL114

Export •

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

THPAL126

Nitrogen Bake-out Procedures at the Vertical High-Temperature UHV-Furnace of the S-DALINAC

cavity, SRF, niobium, linac

3937

R. Grewe, L. Alff, M. Arnold, J. Conrad, S. Flege, M. Major, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany

Funding: Work supported by the Federal Ministry of Education and Research through grant No. 05H15RDRBA.
As the performance limits of bulk Nb srf cavities are reached, our research is focused on materials with superior srf properties like Nb3Sn and NbN. Research on NbN resulted in the "nitrogen-doping" process used for increasing the quality factors of srf cavities for the LCLS-II project. This process leads to delta-phase Nb-N, a phase with higher critical sc parameters than bulk Nb. This phase is formed at temperatures of 800°C in nitrogen atmospheres of 10^-2 mbar. Other crystalline phases of NbN have even better sc parameters. We concentrate our research on applicability of delta-phase NbN for cavities. The delta-phase forms at temperatures of above 1300°C, which is more than most of the furnaces at accelerator facilites are capable of. Since 2005 the Institute for Nuclear Physics at the Technische Universität Darmstadt operates a high temperature vacuum furnace which has been upgraded to allow temperatures of up to 1750°C and bakeouts of niobium samples and cavities in nitrogen atmospheres. We will report on the current status of our research on nitrogen bake-out procedures on Nb samples. The samples have been analyzed at the Material Science Departement with SIMS, REM and XRD.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL126

Export •

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

THPAL127

Structural Investigations of Nitrogen-Doped Niobium for Superconducting RF Cavities

niobium, cavity, ECR, experiment

3940

M. Major, L. Alff, M. Arnold, J. Conrad, S. Flege, R. Grewe, M. Mahr, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
KPH, Mainz, Germany

Funding: Work supported by the German Federal Ministry for Education and Research (BMBF) through grant 05H15RDRBA.
Niobium is the standard material for superconducting RF (SRF) cavities. Superconducting materials with higher critical temperature or higher critical magnetic field allow cavities to work at higher operating temperatures or higher accelerating fields, respectively. Enhancing the surface properties of the superconducting material in the range of the penetration depth is also beneficial. One direction of search for new materials with better properties is the modification of bulk niobium by nitrogen doping. In the Nb-N phase diagram the cubic delta-phase of NbN has the highest critical temperature (16 K). Already slight nitrogen doping of the alpha-Nb phase results in higher quality factors.* Nb samples were N-doped at the refurbished UHV furnace at IKP Darmstadt. Reference samples were annealed in 1 bar nitrogen atmosphere at different temperatures. In this contribution the results on the structural investigations (x-ray diffraction and pole figure, secondary ion mass spectroscopy, scanning electron microscopy) at the Materials Research Department of TU Darmstadt will be presented.
*Grassellino et al., Proc. SRF2015, MOBA06, 48.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL127

Export •

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

THPAL128

Autonomous Topography Detection and Traversal for an Inspection Robot Within the Beamline of Particle Accelerators

experiment, FEL, kicker, heavy-ion

3943

N. Schweizer
Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
I. Pongrac
GSI, Darmstadt, Germany

Particle accelerators feature ultra-high vacuum pipe systems with unique topography, i.e. with a multitude of different vacuum chambers of varying dimensions and varying pipe apertures. In order to be able to examine the interior of the entire vacuum system, even those parts which are not accessible without disassembling large parts of the accelerator, a semi-autonomous robot is being developed which shall traverse and visually inspect the vacuum system of particle accelerators. We present a generic concept based on distance sensors for the inspection robot to detect steps between vacuum chambers and gaps in the beamline. Movement strategies to autonomously overcome these basic obstacles are introduced. For evaluation we use simulations of ideal environments with flat surfaces as well as realistic beam pipe environments of the SIS100 particle accelerator. Additionally, a prototype of our robot concept confirms the implementation of all maneuvers. Results show that obstacles of previously unknown dimensions can be detected and reliably traversed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL128

Export •

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

THPAL133

LASE Surfaces for Mitigation of Electron Cloud in Accelerators

electron, laser, cavity, experiment

3958

B.S. Sian
UMAN, Manchester, United Kingdom
O.B. Malyshev, R. Valizadeh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Vacuum chamber surface characteristics such as the photon and secondary electron yields (PEY and SEY) are critical parameters in the formation of an electron cloud, a serious problem that limits the performance of proton and positron accelerators. A few years ago it was discovered by the Vacuum Solutions Group at Daresbury laboratory that Laser Ablation Surface Engineering (LASE) could provide surfaces with SEY<1 [1,2]. The LASE surfaces are considered as a baseline solution for electron cloud miti-gation in the Future Circular Collider (FCC). However, these surfaces are undergoing further optimisation for the FCC application. While keeping SEY<1 the surfaces should meet the following criteria: Low outgassing, Low particulate generation and low surface resistance. In this paper we will report a number of new surfaces created using the LASE technique with different laser parameters (wavelength, scan speed, pitch, repetition rate, power, and pulse length) and their effect on the SEY, surface re-sistance and vacuum properties, etc

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL133

Export •

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

THPAL150

Development of Tsinghua X-Band High Power Test Facility

klystron, controls, GUI, software

3999

M.M. Peng, D.Z. Cao, W. Gai, Y.L. Jiang, J. Liu, J. Shi, P. Wang
TUB, Beijing, People's Republic of China

The X band high power test facility consists of a 11.424 GHz, 50 MW CPI klystron and a ScandiNova pulse modulator at Tsinghua University has been built since Sept 2017 and the output RF power has reached 60 MW with 200 ns pulse width at a repetition frequency of 10. The klystron output RF pulse will eventually be 50 MW at a 1.5 μs. A group of cylinder pulse compressor will be installed. High gradient accelerating structures for research and TTX will be tested on this facility.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL150

Export •

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

THPMF015

Lifetime and Beam Losses Studies of Partially Strip Ions in the SPS (129Xe³⁹⁺)

injection, factory, beam-losses, electron

4070

S. Hirlaender, R. Alemany-Fernández, H. Bartosik, N. Biancacci, T. Bohl, S. Cettour Cave, K. Cornelis, B. Goddard, V. Kain, M.W. Krasny, M. Lamont, D. Manglunki, G. Papotti, M. Schaumann, F. Zimmermann
CERN, Geneva, Switzerland
K. Kroeger
FSU Jena, Jena, Germany
V.P. Shevelko
LPI RAS, Moscow, Russia
T. Stöhlker, G. Weber
IOQ, Jena, Germany

The CERN multipurpose Gamma Factory proposal relies on using Partially Stripped Ion (PSI) beams, instead of electron beams, as the drivers of its light source. If such beams could be successfully stored in the LHC ring, fluxes of the order of 10¹⁷ photons/s, in the gamma-ray energy domain between 1 MeV and 400 MeV could be achieved. This energy domain is out of reach for the FEL-based light sources as long as the multi TeV electron beams are not available. The CERN Gamma Factory proposal has the potential of increasing by 7 orders of magnitude the intensity limits of the present Inverse Compton Scattering sources. In 2017 the CERN accelerator complex demonstrated its flexibility by producing a new, xenon, ion beam. The Gamma Factory study group, based on this achievement, requested special studies. Its aim was to inject and to accelerate, in the SPS, partially stripped xenon ions Xe³⁹⁺ measure their life time, and determine the relative strength of the processes responsible for the PSI beam losses. This study, the results of which are presented in this contribution, was an initial step in view of the the future studies programmed for 2018 with lead PSI beams.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF015

Export •

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

THPMF022

Study of Possible Beam Losses After Post-Linac Collimation at European XFEL

undulator, radiation, FEL, simulation

4092

S. Liu, W. Decking
DESY, Hamburg, Germany
F. Wolff-Fabris
XFEL. EU, Schenefeld, Germany

The European XFEL has been operating with the undulator beam line SASE1 and SASE3 since April 2017 and February 2018, respectively. Despite of the fact that the post-linac collimation has collimated the beam halo to ~20 σ level*, relative high radiation doses have been measured especially in the diagnostic undulator (DU) section**. In order to find the sources of beam losses after post-linac collimation, BDSIM simulations have been performed. In this paper, we will first present the possible losses generated by the wire scanners upstream of the undulators during a scan. The simulation results will be compared with the measured doses along SASE1 and SASE3 undulators. Based on the simulation results, we will estimate the frequency for wire scanner opera-tions. Besides, the simulations with large extension of beam halo hitting the vacuum chamber aperture transition will also be presented. Finally, other possible radiation dose sources will be discussed.
* S. Liu et al., in Proc. of FEL 2017, Santa-Fe, USA, Aug. 2017, paper TUP003.
** F. Wolff-Fabris et al.,IPAC-2018 contribution.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF022

Export •

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

THPMF031

In-Vacuum APPLE II Undulator

undulator, cryogenics, operation, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF031

Export •

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

THPMF034

Status Report of the Berlin Energy Recovery Linac Project BERLinPro

gun, SRF, cathode, cavity

4127

M. Abo-Bakr, W. Anders, Y. Bergmann, K.B. Bürkmann-Gehrlein, A.B. Büchel, P. Echevarria, A. Frahm, H.-W. Glock, F. Glöckner, F. Göbel, B.D.S. Hall, S. Heling, H.-G. Hoberg, A. Jankowiak, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, G. Kourkafas, J. Kühn, B.C. Kuske, J. Kuszynski, A.N. Matveenko, M. McAteer, A. Meseck, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, L. Pichl, J. Rahn, M.A.H. Schmeißer, O. Schüler, M. Schuster, J. Ullrich, A. Ushakov, J. Völker
HZB, Berlin, Germany
A. Bundels
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany

Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
The Helmholtz-Zentrum Berlin is constructing the Energy Recovery Linac Prototype BERLinPro, a demonstration facility for the science and technology of ERLs for future light source applications. BERLinPro is designed to accelerate a high current (100 mA, 50 MeV), high brilliance (norm. emittance below 1 mm mrad) cw electron beam. We report on the last year's progress, including the comissioning of the gun module as the first SRF component to be installed in BERLinPro.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF034

Export •

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

THPMF036

Status of the Conceptual Design of ALS-U

lattice, emittance, kicker, cavity

4134

C. Steier, A.P. Allézy, A. Anders, K.M. Baptiste, E.S. Buice, K. Chow, G.D. Cutler, S. De Santis, R.J. Donahue, D. Filippetto, J.P. Harkins, T. Hellert, M.J. Johnson, J.-Y. Jung, S.C. Leemann, D. Leitner, M. Leitner, T.H. Luo, H. Nishimura, T. Oliver, O. Omolayo, J.R. Osborn, G.C. Pappas, S. Persichelli, M. Placidi, G.J. Portmann, S. Reyes, D. Robin, F. Sannibale, C. Sun, C.A. Swenson, M. Venturini, S.P. Virostek, W.L. Waldron, E.J. Wallén
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The ALS-U conceptual design promises to deliver diffraction limited performance in the soft x-ray range by lowering the horizontal emittance to about 70 pm rad resulting in two orders of brightness increase for soft x-rays compared to the current ALS. The design utilizes a nine bend achromat lattice, with reverse bending magnets and on-axis swap-out injection utilizing an accumulator ring. This paper shows some aspects of the completed conceptual design of the accelerator, as well as some results of the R&D program that has been ongoing for the last years.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF036

Export •

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

THPMF038

Status of the BESSY VSR Project

cavity, operation, SRF, electron

4138

P. Schnizer, W. Anders, Y. Bergmann, P. Goslawski, H. Hartmut, A. Jankowiak, J. Knobloch, A. Neumann, K. Ott, M. Ries, A. Schälicke, A.V. Vélez
HZB, Berlin, Germany

BESSY VSR is set out to provide a variable pulse pattern to the BESSY II users. This project is now fully funded and heading into its implementation phase. The pulse pattern, consisting of long and short pulses, require inserting cavities providing a 3rd and a 3.5th harmonic of the fundamental harmonic of the ring. Therefore 1.5 and 1.75 GHz cavities are developed with appropriate higher order mode damping spectrum. Similarly the BESSY II ring and injector chain has to be upgraded to provide appropriate diagnostics and increase the injection efficiency. In this paper we give the current status of the project and give an overview of scientific challenges currently being tackled.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF038

Export •

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

THPMF043

Development and Present Status of Photon Factory Light Sources

injection, septum, operation, 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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF043

Export •

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

THPMF046

Precision Charge Measurement of 40~MeV Electron-Beam to Calibrate Air Fluorescence Telescope for Cosmic Ray Observation

electron, ECR, injection, ISOL

4163

T. Shibata
KEK, Ibaraki, Japan
O.C. Shin
OCU, Osaka, Japan

The Telescope Array (TA) is ultra-high energy cosmic ray observation (UHECR). TA is using the fluorescence detectors (FD) for observation the air fluorescence(AFY) which are emitted in the cascade generated by an UHECR in atmosphere. One of the important observables is primary energy of UHECR, however it has 21% systematic uncertainty. For reduction of the uncertainty, we have been operated an 40-MeV electron linear accelerator from 2010 which we have constructed for absolute energy calibration. The accelerator is located at 100 m from FD station, and can shot electron beam which the direction is vertical into the air, the energy is 40-MeV, the pulse width is 1 micro-second, and the beam charge is 160 pC. The AFY efficiency and FD calibration parameters can be calibrated, which means energy scale of UHECR, by observation of the AFY which are generated by the electron beam in the air. The most important beam parameter is beam charge. The requirement of the accuracy of charge measurement is a few %, then we have developed the double faraday cups and one current transfer system. We calibrated the current transfer by the double faraday cups, and we could achieve about 1% accuracy.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF046

Export •

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

THPMF061

Updates on Hardware Developments for SPring-8-II

electron, multipole, permanent-magnet, storage-ring

4209

T. Watanabe, S. Takano
Japan Synchrotron Radiation Research Institute (JASRI), RIKEN SPring-8 Center, Hyogo, Japan
H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

We will report the updates on hardware developments for SPring-8-II including a status on a test half-cell construction. A major upgrade of SPring-8, SPring-8-II, targeting substantial improvements in the light source performance is based on a five-bend achromat lattice at an electron energy of 6 GeV*, and hardware accommodating with the new lattice have been extensively developed**. Some of key features are permanent dipole magnets, SUS vacuum chambers, highly accurate and reliable electron and photon beam position monitors, and an extremely small emittance beam injection from the SACLA linac to the storage ring. In the process of the optimization, we cannot rely merely on independent developments; the high packing factor lattice naturally imposes an integration of the individual efforts into a whole design. Thus, a test-half cell has been constructed as one of important milestones, where we need to carefully look through specification balances between different components, physical and magnetic interferences, etc. The presentation will give overall status on the developments as well as the test half-cell construction.
* H. Tanaka et al., Proc. of IPAC2016, Busan, Korea (2016), p.2867. K. Soutome and H. Tanaka, PRAB 20, 064001 (2017).
** e,g, T. Watanabe et al., PRAB 20, 072401 (2017).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF061

Export •

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

THPMF080

Physical and Chemical Roughness of Alkali-Animonide Cathodes

cathode, electron, emittance, laser

4259

S.S. Karkare, S. Emamian, G. Gevorkyan, H.A. Padmore, A.K. Schmid
LBNL, Berkeley, California, USA
I.V. Bazarov
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A. Galdi
Cornell University, Ithaca, New York, USA

Over the last decade, alkali-antimonides have been investigated as high QE cathodes in green light and more recently as ultra-low intrinsic emittance cathodes in near-threshold red wavelengths at cryogenic temperatures*. Nano-meter scale surface non-uniformities (physical roughness and chemical roughness or work function variations) are thought to limit the smallest possible emittance from these materials at the photoemission threshold under cryogenic conditions**. Despite this, the surfaces of alkali-antimonides have not been well characterized in terms of the surface non-uniformities. Here, we present measurements of both the physical and chemical roughness of alkali-antimonide surfaces using several surface characterization techniques like atomic force microscopy, kelvin probe force microscopy, low energy electron microscopy and near-threshold photoemission electron microscopy and show how such non-uniformities limit the intrinsic emittance.
*L. Cultrera et al Phys. Rev. ST Accel. Beams 18, 113401 (2015)
**J. Feng et al, J. of Appl. Phys. 121, 044904 (2017)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF080

Export •

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

THPMK066

Cryogenic Permanent Magnet Undulator of SSRF

permanent-magnet, undulator, SRF, cryogenics

4449

Y.Z. He, M.F. Qian, H.F. Wang, W. Zhang, Q.G. Zhou
SINAP, Shanghai, People's Republic of China

Funding: Work supported by the State Key Lab of Advanced Metals and Materials (2016-Z03) and the Youth Innovation Promotion Association of CAS (Grant No: 2017305)
The two Cryogenic Permanent Magnet Undulators (CPMU18 with PrFeB magnets P46H and CPMU20 with NdFeB magnets N48H) were designed and developed in SSRF in the past few years (2014-2017).This paper introduces magnetic performance of the permanent magnets, design parameters of the two CPMUs, cryogenic cooling and magnetic field of the two CPMUs and so on. When gap of the two CPMUs is about 6.0 mm, the measurement results showed that the effective magnetic field peak of CPMU18 at 300 K and 77 K was 0.82 T, 0.92T, respectively, and the magnetic field phase error is about 3 degrees and 5 degrees respectively. The effective magnetic field peak of CPMU20 at 300 K and 140 K was 0.94T and 1.03T, respectively, and the magnetic field phase error was 3 degrees and 3.5 degrees respectively.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK066

Export •

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

THPMK100

Setup for Cooled GaAs Cathodes With Increased Charge Lifetime

cathode, electron, cryogenics, simulation

4542

T. Eggert, J. Enders, M. Espig, Y. Fritzsche, N. Kurichiyanil, M. Wagner
TU Darmstadt, Darmstadt, Germany

Funding: DFG (GRK 2128) BMBF (05H15RDRB1)
GaAs photocathode lifetime is limited, and to ensure re- liable operation for high power-applications it is necessary to maximize its charge lifetime. By using a cryogenic sub- volume it is expected to improve the local vacuum condi- tions due to cryogenic adsorption of reactive residual gas molecules. Yielding an enhanced lifetime of the negative- electron-affinity surface of the cathode. Furthermore the cooling of the cathode itself ishould allow higher laser power deposition in the material. Introducing an electrostatic bend is expected to reduces the ion-backbombardment on the cath- ode surface. A dedicated set-up is being developed at the Photo-CATCH test facility in Darmstadt, Germany to measure the charac- teristics of such a cryogenic source. This contribution updates the report given at PSTP 2017.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK100

Export •

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

THPMK125

Development of Non-Evaporable Getter (NEG) Coatings on Small Diameter Vacuum Chambers for Diffraction-Limited Storage Ring

site, target, electron, storage-ring

4611

S. Wang, Y.Z. Hong, R. Huang, X.T. Pei, Y. Wang, W. Wei, B. Zhang, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Design of the fourth generation Diffraction-Limited Storage Ring reduces aperture of vacuum chambers to a few centimeters. To satisfy the small aperture, the intense photon bombardment and the requirement of low pressure, most of the beam pipes need to be deposited with Ti-Zr-V nonevaporable getter (NEG) thin films. NEG can provide distributed pumping and low gas desorption and allow to achieve low pressure in narrow and conductance limited chambers. In this paper, Ti-Zr-V thin film was deposited by DC magnetron sputtering using Ti-Zr-V alloy target. The morphology and thickness of Ti-Zr-V are characterized by Scanning Electron Microscopy (SEM). The average grain size is evaluated using X-ray diffraction (XRD). The composition and the corresponding chemical bonding of the thin film are analyzed by X-ray Photoelectron Spectroscopy (XPS). Finally, the adhesion between the film and substrate and the vacuum performance are evaluated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK125

Export •

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

THPML015

Dielectric Multipactor Discharges at 110 GHz

multipactoring, cavity, experiment, GUI

4684

S. C. Schaub
MIT, Cambridge, Massachusetts, USA
M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA

A 1.5 MW, 110 GHz gyrotron has been used to experimentally measure the maximum sustainable fields on dielectric materials in vacuum. The purpose of this work is to evaluate the suitability of these materials for future applications in high frequency linear accelerators and high power terahertz components. To our knowledge, these are the first measurements of multipactor phenomena in the millimeter wave or terahertz frequency range. Materials tested include alumina, sapphire, fused quartz, crystal quartz, and high resistivity silicon. Dielectric samples were tested both as windows, with electric fields parallel to the surface, and sub-wavelength dielectric rod waveguides, with electric fields perpendicular to the surface. Surface electric fields in excess of 52 MV/m were achieved in 3 microsecond pulses. Visible light emission, absorbed/scattered microwave power, and emitted electrons were measured to characterize the discharges on the dielectric surfaces. The results of these experiments have been compared to theoretical calculations of multipactor discharges, testing these theories at significantly higher frequencies than has been done before.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML015

Export •

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

THPML022

Application of Surface Plasmon Polaritons on Charged particle Beam Diagnostics

radiation, electron, interface, diagnostics

4699

Z.G. Jiang, D. Gu, Q. Gu, M.H. Zhao
SINAP, Shanghai, People's Republic of China

In Recent years, the Cherenkov light radiation transformed from surface plasmon polaritons has been found and proposed for a compact and adjustable light source. As the process is motivated by charged particle beam, the characteristics of the light are not only related with the device but can also reflect certain characteristics of the beam. In this paper, a beam position and energy measurement method has been proposed based on the Cherenkov light radiation transformed from surface plasmon polaritons. Early-stage numerical and analytical investigations are also presented for a planar structure device.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML022

Export •

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

THPML047

Design and Measurement of the X-Band Pulse Compressor for TTX

cavity, GUI, coupling, ISOL

4745

Y.L. Jiang, H.B. Chen, C. Cheng, W. Gai, J. Shi, P. Wang, Z.H. Wang, X.W. Wu, H. Zha
TUB, Beijing, People's Republic of China

A radio frequency (RF) pulse compressor had been designed for the X-band (11.424 GHz) high power test stands at the Accelerator Laboratory of Tsinghua University. It is the SLED-I type pulse compressor, which uses a high quality factor corrugated circular cavity to store the RF power. An RF polarizer couples two quadrature modes into the cavity so that the pulse compressor needs only one cavity. The cavity implements HE1-1-14 mode, with the Q0 of 115, 000 and the coupling factor (β) of 3.23. The design and the microwave measurement before brazing of this pulse compressor are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML047

Export •

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

THPML053

Computational Screening for Low Emittance Photocathodes

electron, cathode, database, emittance

4755

J.T. Paul, R.G. Hennig
University of Florida, Gainesville, Florida, USA
I.V. Bazarov, A. Galdi
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
S.S. Karkare, H.A. Padmore
LBNL, Berkeley, California, USA

The majority of photocathode materials in use in accelerator applications have been discovered empirically through trial and error with little guidance from material science calculations. Alternatively, one can envision a process which is heavily guided by computational search using latest advances in density functional theory (DFT). In this work, the MaterialsProject database is searched for potential single crystal photocathodes that would be suitable for ultralow emittance beam production. The materials in the database are initially screened on the basis of experimental practicality. Following this, the expected emittance is calculated from the DFT computed band structures for the pre-screened materials using the conservation of energy and transverse momentum during photoemission. Based on such computational screening, we provide a list of potential low emittance photocathode materials which can be investigated experimentally as high brightness electron sources.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML053

Export •

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

THPML059

Re-Commissioning the Front End Test Stand Negative Hydrogen Ion Source, Beam Transport and Interlocks

ion-source, rfq, MMI, high-voltage

4769

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

The front end test stand (FETS) is a demonstrator for a future high intensity, high duty factor negative hydrogen (H') ion injector. With the radio-frequency quadrupole (RFQ) nearing installation, the ion source has been re-commissioned in preparation for long-term operation. The 3 MeV beam exceeds the radio-activation energy of common engineering materials, so radiation shielding has been erected. A new interlocking scheme has been signed-off which integrates the existing ion source high voltage area with the new shielding access points, to ensure that the machine can operate safely during beam production. The existing vacuum arrangement has been extended to in-clude the RFQ and medium energy beam transport (MEBT) line. A new programmable logic controller (PLC) has been built to operate the entire vacuum chain. The ion source high voltage equipment has been upgraded to minimise both spark rate and intensity. A collimating aperture and Faraday cup have been installed after the low energy beam transport (LEBT) section to ensure the beam is well aligned for injection into the RFQ. Re-commissioning the ion source has given a rugged shakedown of all these new systems before beam is required for the RFQ.
*scott.lawrie@stfc.ac.uk

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML059

Export •

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

THPML112

Preliminary Design and Calculation of Button BPM for the HALS Storage Ring

storage-ring, HOM, electronics, impedance

4929

F.F. Wu, F.L. Gao, L.T. Huang, X.Y. Liu, P. Lu, B.G. Sun, J.H. Wei, Y.L. Yang, T.Y. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China
L. Lin
Huizhou University, Huizhou, People's Republic of China

Funding: Supported by the National Science Foundation of China (Grant No.11705203, 11575181，11605202) and the National Key Research and Development Program of China(No. 2016YFA0402000)
Button BPM is being designed for the HALS storage ring, which is a diffraction-limited storage ring (DLSR) located at the NSRL in Hefei city. Since beam size is very small, the required resolution of 50 nm for beam position measurement need to be obtained. The parameters of the HALS Button BPM are initially determined. According to theoretical formulas, electrode induced signal is calculated and the relationship between electrode induced signal and beam current is obtained. Signal to noise ratio(SNR)of the HALS Button BPM is calculated with different beam current when the required resolution is 50 nm. The results show that the SNR is well when beam current is very low. In addition, the effects of BPM RF frequency and button electrode radius on SNR are analyzed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML112

Export •

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

THPML128

Production and Secondary Electron Yield Test of Amorphous Carbon Thin Film

electron, synchrotron, synchrotron-radiation, site

4980

Y.X. Zhang, X.Q. Ge, S.W. Wang, Y. Wang, W. Wei, B. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Amorphous carbon (a-C) thin film applied to vacuum chambers of high-energy particle accelerators can decrease secondary electron yield（SEY）and suppress electron-cloud effectively. A dc magnetron sputtering apparatus to obtain a-C film has been designed. With the equipment, a-C thin film can be deposited on the inner face of stainless steel pipes ultimately which is uniform and high-quality. Meanwhile, it is found that a-C has a low SEY＜1.2 measured by the secondary electron emission measurement set-up in the National Synchrotron Radiation Laboratory. The result indicates that a-C is an ideal material for modern accelerators.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML128

Export •

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

THPML129

Deposition and Characterization of TiZrHfV films by DC Magnetron Sputtering

electron, controls, storage-ring, target

4983

X.Q. Ge, T.L. He, X.T. Pei, Y.G. Wang, Y. Wang, W. Wei, B. Zhang, Y.X. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

The new generation of accelerators places higher demands on the surfaces of vacuum chamber materials. Search for low secondary electron yield (SEY) materials and an effective vacuum chamber surface treatment process, which can effectively reduce the electronic cloud effect, are important early works for the new generation of accelerators. In this work, we revealed the SEY characteristics of Ti-Zr-Hf-V NEG films and Ti-Zr-V NEG films which were deposited on Si (111) substrates using direct current magnetron sputtering method. The surface morphology and surface chemical bonding information were collected by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). With the same parameters, the maximum SEY of Ti-Zr-Hf-V NEG films and Ti-Zr-V NEG films are 1.24 and 1.51, respectively. These results are of great significance for the next-generation particle accelerators.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML129

Export •

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

THPML131

A NEW PRODUCTION PROCESS FOR UCx TARGETS FOR RADIOACTIVE ISOTOPE BEAMS AT TRIUMF

target, TRIUMF, ISOL, ISAC

4990

M. S. Cervantes, P. Fouquet-Métivier, A. Gottberg, P. Kunz, L. Lambert, A. Mjøs, J. Wong
TRIUMF, Vancouver, Canada
M. S. Cervantes
UVIC, Victoria, Canada
P. Fouquet-Métivier
ENSCM, Montpellier, France
A. Gottberg
Victoria University, Victoria, B.C., Canada

TRIUMF has the objective of producing radioactive isotope beams (RIB) using the ISOL method. Radioactive isotopes are used in experiments in different areas of science. At the TRIUMF-ISAC facility, a 500 MeV proton driver beam impinges onto different targets and induces nuclear reactions in them. The isotopes obtained in this way then diffuse out of the target material before they are ionized and extracted to form an isotope beam. Targets of uranium carbide with excess of graphite (UCx) are the most requested targets at TRIUMF. ARIEL, TRIUMF's flagship project, aims at increasing the radioactive isotope production capabilities to satisfy the growing demand of radioactive isotopes. The current production method of UCx targest does not have the means to supply enough UCx targets to satisfy ARIEL's demand, therefore, a new method for efficient UCx target material synthesis is being developed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML131

Export •

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

THPML135

Design of the Combined Function Dipole-Quadrupoles (DQS) with High Gradients

quadrupole, dipole, lattice, storage-ring

5001

Z.L. Ren, C. Chen, T.L. He, L. Wang, X.Q. Wang, H. Xu, B. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by the National Nature Science Foundation of China under Grant Nos.11375176 * hlxu@ustc.edu.cn **zhbo@ustc.edu.cn
Combined dipole-quadrupoles (DQs) can be obtained with the design of tapered dipole or offset quadrupole. However, the tapered dipole design can not achieve a high gradient field, as it will lead to poor field quality in the low field area of the magnet bore, and the design of offset quadrupole will increase the magnet size and power consumption. Finally, the dipole-quadrupole design developed is between the offset quadrupole and septum quadrupole types. The dimensions of the poles and the coils of the low field side have been reduced. The 2D pole profile is simulated and optimized by using POSSION and Radia, while the 3D modle using Radia and OPERA-3D. The end shimming and chamfer are modelled to meet the field uniformity requirement.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML135

Export •

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