Keyword: SRF
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MOYPLM2 SRF Operation at XFEL: Lessons Learned After More Than One Year FEL, cavity, operation, linac 12
 
  • D. Kostin, V. Ayvazyan, J. Branlard, W. Decking, L. Lilje, M. Omet, T. Schnautz, E. Vogel, N. Walker
    DESY, Hamburg, Germany
  
  The European XFEL is the largest high-field SRF installation in the world and has now been in operation more than a year. It serves as a "prototype" for other facilities being constructed or in the planning stages. Performance of the operation of the SRF system over this period of time and the lessons learned will be discussed.  
slides icon Slides MOYPLM2 [4.351 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOYPLM2  
About • paper received ※ 10 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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MOPGW008 Transparent Injection for ESRF-EBS injection, kicker, sextupole, power-supply 78
 
  • S.M. White, N. Carmignani, M. Dubrulle, M. Morati, P. Raimondi
    ESRF, Grenoble, France
  
  The commissioning of the ESRF-EBS storage ring will start in December 2019 ultimately providing a horizontal emittance of 130 pm, 30 times lower than the present one. Due to the reduced beam lifetime top-up operation will be required for all operating modes. Transparent injection, i.e. with negligible perturbations on the stored beam, is necessary to allow continuous data acquisition for beam lines experiments. Several options have been considered at ESRF to reduce these perturbations down to a fraction of the rms beam size: i) new kickers power supplies with slow ramping time to facilitate active compensation are under development and will be implemented in the coming years ii) in parallel, long term solutions using non-linear kickers and longitudinal on-axis injection have been investigated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW008  
About • paper received ※ 13 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPGW045 A Fast Method for Multi-Objective Nonlinear Dynamics Optimization of a Storage Ring storage-ring, lattice, sextupole, dynamic-aperture 190
 
  • J.J. Tan, Z.H. Bai, W. Li, L. Wang, P.H. Yang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  
  Multi-objective evolutionary algorithms (MOEAs), including multi-objective genetic algorithm and particle swarm optimization algorithm, have been widely applied in the nonlinear dynamics optimization of storage ring light sources. In the optimization, the direct tracking of objectives, which are, for example, dynamic aperture (DA) and momentum aperture, is very time-consuming. We noticed that there is some positive correlation between on- and off-momentum nonlinear dynamics performances, which can be used to reduce the computation time when applying MOEAs. In this paper, a fast method is proposed, in which a strategy is introduced to speed up the process of optimizing nonlinear dynamics using MOEAs. Taking the SSRF storage ring as an example, on- and off-momentum DAs are optimized using MOEAs with and without the fast strategy, and then a comparison is made to demonstrate the fast method.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW045  
About • paper received ※ 15 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPMP040 US Contributions to the High Luminosity LHC Upgrade - Focusing Quadrupoles and Crab Cavities cavity, luminosity, quadrupole, HOM 536
 
  • G. Apollinari, G. Ambrosio, R.H. Carcagno, SF. Feher, L. Ristori
    Fermilab, Batavia, Illinois, USA
  
  In the early 2000’s, the US High Energy Physics community contributing to the Large Hadron Collider (LHC) launched the LHC Accelerator R&D Program) (LARP), a long-vision focused R&D program, intended to bring the Nb3Sn and other technologies to a maturity level that would allow applications in HEP machines. Around 2015, the technologies developed by LARP were mature enough to allow the spin-off of a major upgrade project to the LHC complex, the High Luminosity LHC (HL-LHC). This paper will focus on the US contribution to HL-LHC, namely the large-aperture low-beta focusing Nb3Sn quadrupoles and the Radio Frequency Dipole (RFD) Crab Cavities, located in close proximity to the ATLAS and CMS experiments. This contribution, called the HL-LHC Accelerator Upgrade Project (HL-LHC AUP), focuses on production of these quadrupoles and cavities by sharing the work among a consortium of US Laboratories (FNAL, LBNL, BNL and SLAC) and Universities and in close connection with the CERN-led HL-LHC Collaboration. The collaboration achieved commonality of specifications and uniformity of performance. Final development of design, construction and first results from the prototypes are described to indi-cate the status of these critical components for HL-LHC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP040  
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPMP050 Performance of CeC PoP Accelerator electron, FEL, gun, hadron 559
 
  • I. Pinayev, Z. Altinbas, J.C. Brutus, A.J. Curcio, A. Di Lieto, T. Hayes, R.L. Hulsart, P. Inacker, Y.C. Jing, V. Litvinenko, J. Ma, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, M.G. Minty, G. Narayan, F. Severino, K. Shih, Z. Sorrell, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron cooling experiment is aimed for demonstration of the proof-of-principle demonstration of reduction energy spread of a single hadron bunch circulating in RHIC. The electron beam should have the required parameters and its orbit and energy should be matched to the hadron beam. In this paper we present the achieved electron beam parameters including emittance, energy spread, and other critical indicators. The operational issues as well as future plans are also discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP050  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPMP051 56 MHz SRF System for SPHENIX Experiments at RHIC cavity, operation, HOM, detector 562
 
  • Q. Wu, M. Blaskiewicz, K. Mernick, S. Polizzo, F. Severino, K.S. Smith, T. Xin
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
The sPHENIX experiment is a proposal for a new detector at the Relativistic Heavy Ion Collider (RHIC), that plans to expand on discoveries made by RHIC’s existing STAR and PHENIX research groups. To minimize the luminosity outside the 20 cm vertex detector and keeping the radiation to other detector components as low as possible, a 56 MHz SRF system is added to the existing RHIC RF systems to compress the bunches with less beam loss. The existing 56 MHz SRF cavity was commissioned in previous RHIC runs, and contributed to the luminosity at a voltage of 300kV with thermal limitations from the Higher Order Mode coupler at high field, and at 1MV while using its fundamental damper for HOM damping. In this paper, we will analyze and compare the effect of different RF systems at various scenarios, and discuss possible solutions to the Higher Order Mode (HOM) damping scheme to bring the cavity to 2 MV. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP051  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB087 Proposal for a High Transformer Ratio CW Dielectric Accelerator electron, experiment, wakefield, operation 773
 
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • J.C. Brutus, Y.C. Jing, I. Pinayev, G. Wang
    BNL, Upton, Long Island, New York, USA
  • M.E. Conde, C.-J. Jing, J.G. Power
    ANL, Argonne, Illinois, USA
  • A. Kanareykin
    Euclid Beamlabs LLC, Bolingbrook, USA
  • N. Vafaei-Najafabadi
    UCLA, Los Angeles, California, USA
  
  Advanced CW accelerators are one of high priority directions identified by Advanced Accelerator Concepts Research Roadmap Workshop Report *. High transformer ratio of beam-driven accelerators is critically important for cost-effective FEL systems. We present a proposed experiment for demonstrating a high transformer ratio CW dielectric accelerator using operational SRF accelerator built for Coherent electron Cooling experiment. This accelerator operates with CW electron beam comprised of 78 kHz train of electron bunches. Electron bunches with controllable longitudinal and charge up to 10 nC per bunch are generated in 1.25 MV SRF photo-electron gun. This bunches are ballistically compressed to duration of 10-to-30 psec and accelerated to 15 MeV in SRF linac**. Such bunches would be excellent drivers of high-transformer ratio DWA accelerators. In this paper we present expected performance of proposed CW DWA accelerator.
*Advanced Accelerator Concepts Research Roadmap Workshop Report, 2016,
*V.N. Litvinenko et al., In proc.of FEL’17, Santa Fe, NM, USA, August 20-25, 2017, p. 132 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB087  
About • paper received ※ 19 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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MOPTS034 Advanced Beam Dynamics Design for the Superconducting Heavy Ion Accelerator HELIAC cavity, linac, heavy-ion, acceleration 928
 
  • M. Schwarz, M. Basten, M. Busch, T. Conrad, H. Podlech
    IAP, Frankfurt am Main, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, C. Burandt, M. Heilmann, S. Lauber, J. List, A. Rubin, S. Yaramyshev
    GSI, Darmstadt, Germany
  • K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu
    HIM, Mainz, Germany
  • S. Lauber, J. List
    KPH, Mainz, Germany
  
  Funding: Work supported by BMBF contr. No. 05P18RFRB1, EU Framework Programme H2020 662186 (MYRTE) and HIC for FAIR
The standalone superconducting (SC) continuous wave (CW) heavy ion linac HELIAC (HElmholtz LInear ACcelerator) is a common project of GSI and HIM under key support of IAP Frankfurt and in collaboration with Moscow Engineering Physics Institute (MEPhI) and Moscow Institute for Theoretical and Experimental Physics (KI-ITEP). It is intended for future experiments with heavy ions near the Coulomb barrier within super-heavy element (SHE) research and aims at developing a linac with multiple CH cavities as key components downstream the High Charge State Injector (HLI) at GSI. The design is challenging due to the requirement of intense beams in CW mode up to a mass-to-charge ratio of 6, while covering a broad output energy range from 3.5 to 7.3 MeV/u with minimum energy spread. In 2017 the first superconducting section of the linac has been successfully commissioned and extensively tested with beam at GSI. In the light of experience gained in this research so far, the beam dynamics layout for the entire linac has recently been updated and optimized with particular emphasis on realistic assumptions of cavity gap and drift lengths as well as gap voltage distributions for CH3’CH11. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS034  
About • paper received ※ 30 April 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPTS042 Hardware Commissioning of the Renovated PIAVE Injector at INFN-LNL rfq, operation, MMI, ion-source 949
 
  • G. Bisoffi, L. Bellan, J. Bermudez, E. Bissiato, D. Bortolato, F. Chiurlotto, M. Comunian, T. Contran, A. Facco, E. Fagotti, P. Francescon, A. Friso, A. Galatà, C.S. Gallo, M.G. Giacchini, M. Lollo, D. Martini, M.O. Miglioranza, P. Modanese, M. Montis, E. Munaron, G. Nigrelli, S. Pavinato, M. Pengo, A. Pisent, M. Poggi, L. Pranovi, M. Rossignoli, D. Scarpa
    INFN/LNL, Legnaro (PD), Italy
  • V. Andreev
    ITEP, Moscow, Russia
  • M.A. Bellato
    INFN- Sez. di Padova, Padova, Italy
  
  During 2018, the PIAVE superconducting linac injector at INFN-LNL, based on superconducting RFQs and two cryomodules with quarter wave resonators, underwent a renovation plan. This operation was strictly related to the one carried out on ALPI [1], which will become a post-accelerator for both stable and exotic beams in a near future. PIAVE Quarter Wave Resonator (QWR) cryomod-ules, in operation since 2006, were moved to ALPI to be used for the acceleration of both stable beams and future exotic beams delivered from the cyclotron target-ion-source station, after appropriate purification, charge breeding and pre-acceleration stages. In order to cope with the removal of the two QWR cryomodules in PIAVE, a newly designed 80 MHz room temperature buncher was designed, built and tested: the buncher is required so as to match the longitudinal phase space between PIAVE su-perconducting RFQs (SRFQ1 and SRFQ2) and ALPI. In the same period, substantial refurbishments on the ECR ion source platform were carried out, in particular on its infrastructure and safety equipment. A problem on an electronic component on SRFQ2, though quickly fixed, delayed beam commissioning of the PIAVE injector, which will start at the end of May 2019.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS042  
About • paper received ※ 30 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS051 Lattice Design for 5MeV-125mA CW RFQ Operation in the LIPAc linac, rfq, MMI, MEBT 977
 
  • Y. Shimosaki, A. Kasugai, K. Kondo, K. Sakamoto, M. Sugimoto
    QST, Aomori, Japan
  • L. Bellan, M. Comunian, E. Fagotti, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • B. Brañas Lasala, C. Oliver, I. Podadera
    CIEMAT, Madrid, Spain
  • P. Cara
    IFMIF/EVEDA, Rokkasho, Japan
  • N. Chauvin
    CEA-IRFU, Gif-sur-Yvette, France
  • G. Duglue, H. Dzitko
    F4E, Germany
  • R. Heidinger
    Fusion for Energy, Garching, Germany
  • H. Kobayashi, K. Takayama
    KEK, Ibaraki, Japan
  
  The installation and commissioning of the LIPAc are ongoing under the Broader Approach agreement, which is the prototype accelerator of the IFMIF for proof of princi-ple and design. The deuteron beam will be accelerated by the RFQ linac from 100 keV to 5 MeV during the com-missioning phase-B and by the SRF linac up to 9 MeV during the phase-C. The commissioning phase-B+ will be implemented between phase-B and C to complete the engineering validation of the RFQ linac before installing the SRF linac. The lattice for the deuteron beam of 5 MeV and 125 mA at the commissioning phase-B+ was designed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS051  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUXXPLM2 SRF Cavity Fault Classification Using Machine Learning at CEBAF cavity, cryomodule, operation, GUI 1167
 
  • A.D. Solopova, A. Carpenter, T. Powers, Y. Roblin, C. Tennant
    JLab, Newport News, Virginia, USA
  • K.M. Iftekharuddin, L. Vidyaratne
    ODU, Norfolk, Virginia, USA
  
  The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab is the first large high power CW recirculating electron accelerator which makes use of SRF accelerating structures configured in two antiparallel linacs. Each linac consists of twenty C20/C50 cryomodules each containing eight 5-cell cavities and five C100 upgrade cryomodules each containing eight 7-cell cavities. Accurately classifying the source of cavity faults is critical for improving accelerator performance. In addition to archived signals sampled at 10 Hz, a cavity fault triggers a waveform acquisition process where 16 waveform records sampled at 5 kHz are recorded for each of the 8 cavities in the effected cryomodule. The waveform record length is sufficiently long for transient microphonic effects to be observable. Significant time is required by a subject matter expert to analyze and identify the intra-cavity signatures of imminent faults. This paper describes a path forward that utilizes machine learning for automatic fault classification. Post-training identification of the physical origins of faults are discussed, as are potential machine-trained model-free implementations of trip avoidance procedures. These methods should provide new insights into cavity fault mechanisms and facilitate intelligent optimization of cryomodule performance  
slides icon Slides TUXXPLM2 [4.404 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUXXPLM2  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPMP047 Upgrade of the Cryogenic Control System for SRF Modules at the Taiwan Light Source controls, cryogenics, operation, interface 1356
 
  • F.-T. Chung, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, Y.T. Li, M.-C. Lin, Z.K. Liu, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
  
  An upgrade of the cryogenic control system for superconducting radio-frequency (SRF) modules of the Taiwan Light Source (TLS) has been completed. The biggest challenge was to recover all protection and operational functions, while minimizing the quantity of vented helium from SRF modules while replacing valve controllers. Gradually, this work was finished within several one- and ten-day scheduled machine shutdown periods for accelerator maintenance. No large helium vent nor pollution of the cryogenic system occurred during all component replacements and function verifications. Functions of the cryogenic electronics were improved, whereas the valve controllers are upgraded to new versions to increase reliability and availability. Communications with the data acquisition system was also secured by buffered signal processing module so that device shutdown of the data acquisition system will not interrupt the cryogenic valve operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP047  
About • paper received ※ 29 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW005 Preparation of the EBS Beam Commissioning MMI, storage-ring, controls, injection 1388
 
  • S.M. Liuzzo, N. Carmignani, A. Franchi, T.P. Perron, K.B. Scheidt, E.T. Taurel, L. Torino, S.M. White
    ESRF, Grenoble, France
  
  In 2020 the ESRF storage ring will be upgraded to a Hybrid Multi Bend Achromat (HMBA) lattice. The commissioning of the new ring will require dedicated tools, either updated from the existing ones or newly developed. Most of the software and procedures were tested on the existing storage ring before its decommissioning. In particular we present experiments on first-turn steering and beam accumulation, check of magnet polarity and calibration, and injection tuning. The use of a control-system simulator proved to be crucial for the debugging of the software and the development of the new control system, as far as beam measurements and manipulations are concerned.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW005  
About • paper received ※ 26 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW006 Measurements of the Momentum Compaction Factor of the ESRF Storage Ring radiation, undulator, electron, synchrotron 1392
 
  • N. Carmignani, W. De Nolf, A. Franchi, C. Sahle, L. Torino
    ESRF, Grenoble, France
  • B. Nash
    RadiaSoft LLC, Boulder, Colorado, USA
  
  In a storage ring, the momentum compaction factor can be obtained by measuring the variation of the beam energy as a function of the RF frequency. In this paper we present the measurement of the momentum compaction factor from two different methods. With the first, we measure the variation of the undulator spectra for different RF frequencies. With the second, we measure the variation of the hard x-rays flux produced by a dipole for different RF frequencies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW006  
About • paper received ※ 29 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW009 THE ESRF FROM 1988 TO 2018, 30 YEARS OF INNOVATION AND OPERATION operation, vacuum, injection, emittance 1400
 
  • J.-L. Revol, L. Farvacque, L. Hardy, P. Raimondi
    ESRF, Grenoble, France
  
  In 1988, eleven European countries joined forces to build the European Synchrotron Facility in Grenoble [France]. The ESRF was the first third-generation light source worldwide. After 30 years of innovation and user operation, the present storage ring was shut down to leave room for a new and brighter source. This paper describes the evolution of the facility from its origin to the Ex-tremely Bright Source (EBS). Firstly, the operational aspects including reliability and beam modes are consid-ered. This is followed by the presentation of the progress of lattice and the implementation of top-up. Finally, the development of the radio frequency and vacuum systems are discussed. To conclude, the lessons learned from 30 years operation are summarized, especially in view of EBS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW009  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB055 First Results of the IVU16 Prototype Undulator Measurements FEL, vacuum, undulator, MMI 1808
 
  • C. Yu, Y.Z. He, X. Hu, Z. Jiang, M.F. Qian, Y.M. Wen, S. Xiang, L. Yin, J.D. Zhang, W. Zhang, Q.G. Zhou
    SINAP, Shanghai, People’s Republic of China
  • H.X. Deng, B. Liu, D. Wang
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • H.F. Wang, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  
  The Shanghai Synchrotron Radiation Facility (SSRF) has developed a 16 mm period length, 4 mm gap, in-vacuum undulator (IVU) that is planned to be installed and tested in the 1.5 GeV SXFEL-SBP beam line. This paper will describe the main parameters of the undulator and the key design choices that have been made. The first undulator prototype was assembled and magnetically tested. First measurements with vacuum chamber will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB055  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS078 Coherent Electron Cooling (CeC) Experiment at RHIC: Status and Plans electron, FEL, experiment, simulation 2101
 
  • V. Litvinenko, K. Mihara
    Stony Brook University, Stony Brook, USA
  • Z. Altinbas, J.C. Brutus, A. Di Lieto, D.M. Gassner, T. Hayes, P. Inacker, J.P. Jamilkowski, Y.C. Jing, R. Kellermann, J. Ma, G.J. Mahler, M. Mapes, R.J. Michnoff, T.A. Miller, M.G. Minty, G. Narayan, M.C. Paniccia, D. Phillips, I. Pinayev, S.K. Seberg, F. Severino, J. Skaritka, L. Smart, K.S. Smith, Z. Sorrell, R. Than, J.E. Tuozzolo, E. Wang, G. Wang, Y.H. Wu, B.P. Xiao, T. Xin, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and NSF Grant No. PHY-141525
We will present currents status of the CeC experiment at RHIC and discuss plans for future. Special focus will be given to unexpected experimental results obtained during RHIC Run 18 and discovery of a previously unknown type of microwave instability. We called this new phenomenon micro-bunching Plasma Cascade Instability (PCI). Our plan for future experiments includes suppressing this instability in the CeC accelerator and using it as a broad-band amplifier in the CeC system. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS078  
About • paper received ※ 19 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS079 Overcoming Multipacting Barriers in SRF Photoinjectors cavity, gun, electron, cathode 2105
 
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • V. Litvinenko, G. Narayan, I. Pinayev, F. Severino, K.S. Smith
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  
  Superconducting RF (SRF) photoinjectors are considered to be a potential breakthrough in the area of high brightness electron sources. However, there is always the very important question of the compatibility of SRF cavities and high quantum efficiency (QE) photocathodes. A deposition of active elements from high QE photocathodes on the surface of a cavity makes it more vulnerable to multipacting (MP) and could affect the operation of an SRF gun. On the other side, MP can significantly reduce the lifetime of a photocathode. It is well known in the SRF community that a strong coupling, high forward power and sufficient cleanliness of cavity walls are the key components to overcome a low-level MP zone. In this paper we present a theoretical model of passing a MP barrier which could help estimate the desirable conditions for successful operation of an SRF gun. We demonstrate our results for the 113 MHz SRF photo-injector for Coherent electron Cooling (CeC) alongside with the experimental observations and 3D simulations of the MP discharge in the cavity. The results of the theoretical model and simulations show good agreement with the experimental results, and demonstrate that, if approached carefully, MP zones can be easily passed without any harm to the photocathode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS079  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS083 Simulations and Experimental Plans for a High-Repetition-Rate Field-Enhanced Conduction-Cooled Superconducting RF Electron Source cavity, electron, cathode, simulation 2113
 
  • O. Mohsen, A. McKeown, D. Mihalcea, P. Piot, I. Salehinia
    Northern Illinois University, DeKalb, Illinois, USA
  • R. Dhuley, M.G. Geelhoed, D. Mihalcea, P. Piot, J.C.T. Thangaraj
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by DOE awards DE-SC0018367 with NIU and DE-AC02-07CH11359 with Fermilab.
We present a novel RF design for a field enhanced electron source driven by field emission cathodes. The proposed electron source relies on the enhanced high electric field gradients at the cathode to simultaneously extract and accelerate electrons. The system will be tested in a conduction-cooled superconducting radio-frequency cavity recently demonstrated at Fermilab. In this paper, we present electromagnetic and thermal simulations of the setup that support the feasibility of the design. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS083  
About • paper received ※ 18 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS112 Stand-alone Accelerator System Based on SRF Quarter-wave Resonators cryomodule, operation, cavity, vacuum 2185
 
  • S.V. Kutsaev, R.B. Agustsson, R.D. Berry, D. Chao
    RadiaBeam, Santa Monica, California, USA
  • Z.A. Conway
    ANL, Argonne, Illinois, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy under contracts DE-SC0017101 and DE-AC02-06CH11357. This research used resources of DOE ANL’s ATLAS facility.
Superconducting accelerators are large and complex systems requiring a central refrigerator and distributed transfer systems to supply 2-4 K liquid helium. Stand-alone, cryocooler-based systems are of interest both to scientific facilities and industrial applications, as they do not require large cryogenic infrastructure and trained specialists for operation. Here we present our approach to the challenge of using low-power commercially available cryocoolers to operate niobium superconducting resonators at 4.4 K with high accelerating voltages and several watts of heating. Engineering and design results from RadiaBeam Systems, collaborating with Argonne National Laboratory, for a stand-alone liquid-cooled cryomodule with 10 Watts of 4.4 K cooling capacity housing a 72.75 MHz quarter-wave resonator operating at 2 MV for synchronous ions travelling at 7.7% of speed of light will be discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS112  
About • paper received ※ 30 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS118 LASA Activities on Surface Treatment of Low-beta Elliptical Cavities cavity, FEL, cathode, superconductivity 2207
 
  • M. Bertucci, A. Bignami, A. Bosotti, M. Chiodini, A. D’Ambros, P. Michelato, L. Monaco, R. Paparella, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  • D. Rizzetto, M. Rizzi
    Ettore Zanon S.p.A., Schio, Italy
  • L. Sagliano
    ESS, Lund, Sweden
  
  This paper describes the efforts made by LASA on the development of surface treatments for low-beta elliptical cavities, for the current series production of ESS and the foreseen series production of PIP-II. The traditional techniques of buffered chemical polishing and electropolishing are here discussed taking into account the industrial environment, the practical issues due to the size and geometry of such cavities and according to the required qualification values for quality factor and accelerating gradient.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS118  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS120 Status of the PIP-II Activities at INFN-LASA cavity, niobium, linac, interface 2215
 
  • R. Paparella, M. Bertucci, A. Bignami, A. Bosotti, M. Chiodini, A. D’Ambros, P. Michelato, L. Monaco, C. Pagani, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • J.F. Chen
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  • L. Sagliano
    ESS, Lund, Sweden
  
  INFN-LASA joined the international effort for the PIP-II project in Fermilab and it is expected to build the 650 MHz superconducting cavities required by the low-beta section of the 800 MeV front-end proton linac, as recently signed by US DOE and Italian MIUR. After developing the electro-magnetic and mechanical design, INFN-Milano started the prototyping phase by producing five single-cells and two complete 5-cells cavities. In a joint effort with Fermilab the road for the optimal surface treatment for such low-beta resonators has started in order to approach the existing state-of-the-art performances of beta 1 cavities. This paper reports the status of PIP-II activities at INFN-LASA summarizing manufacturing experience and preliminary experimental results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS120  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW045 Application of Clustering by Fast Search and Find of Density Peaks to Beam Diagnostics at SSRF GUI, storage-ring, diagnostics, electron 2581
 
  • R. Jiang, Y.B. Leng
    SSRF, Shanghai, People’s Republic of China
  
  With the increased technological complexity of accelera-tors, meeting the demand of beam diagnostics and opera-tion need more powerful and faster methods. And detect-ing the accuracy and stability of beam position moni-tors(BPMs) are important for all kinds of measurement systems and feedback systems in particle accelerator field. As an effective tool for data analysis and automa-tion, the machine learning methods had been used in accelerator physics field, recently. Among machine learn-ing methods, the clustering by fast search and find of density peaks as a typical unsupervised learning algo-rithms could be performed directly without training in arbitrary accelerator systems and could discover un-known patterns in the data. This paper used clustering by fast search and find of density peaks to detect faulty beam position monitor or monitoring beam orbit stability by analysis five typical parameters, that is beta oscilla-tion of X and Y direction(BetaX and BetaY), transverse oscillation of X and Y direction(AmpX and AmpY) and energy oscillation(AmpE). The results showed that cluster-ing by fast search and find of density peaks could classi-fy beam data into different clusters on the basis of their similarity. And that, aberrant run data points could be detected by decision graph. Morever, analysis results demonstrate the characteristic parameters AmpE, AmpX and BetaX amplitude have the same effect to distinguish the faulty BPMs and the AmpY and the BetaY amplitude are also.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW045  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW049 Deep Learning Applied for Multi-Slit Imaging Based Beam Size Monitor network, simulation, synchrotron, synchrotron-radiation 2587
 
  • B. Gao, Y.B. Leng
    SSRF, Shanghai, People’s Republic of China
  • X.Y. Xu
    SINAP, Shanghai, People’s Republic of China
  
  In order to satisfy the requirement of high speed measurement and improve the accuracy of BSM (beam size monitor), multi-slit imaging based BSM has been proposed by SSRF at 2017. However, it is very difficult to deconvolve the image and figure out the beam size, which requires dedicated algorithms to solve this issue. Deep learning is one of the most popular algorithms, which can learn to mimic any distribution of data. In the region of Beam instrumentation, they can be taught to deal with many difficult problem. In this paper, multi-layer neural network is used to process the images from the multi-slit imaging system. Training processes, struct of the neural networks and the result of the experiments will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW049  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW061 Bunch Length Measurement Using Multi-Frequency Harmonic Analysis Method at SSRF experiment, storage-ring, operation, framework 2616
 
  • Y.M. Zhou, B. Gao, Y.B. Leng, N. Zhang
    SSRF, Shanghai, People’s Republic of China
  
  Harmonics method in the frequency domain is an effective and inexpensive bunch length measurement method, which was implemented at the Shanghai Synchrotron Radiation Facility (SSRF). A multi-frequency bunch-bybunch length measurement system using an integrated RF conditioning module will be established to reduce the system noise and signal reflection, and to improve the bunch length measurement accuracy as well. The module consists of power splitters, band-pass filters, mixers and so on. The main function of the integrated RF conditioning module is to extract the beam signals at 500MHz, 1.5GHz, 2GHz, and 3GHz operating frequency. Raw data are acquired by a high-precision digitizer and analyzed by MATLAB code. The absolute bunch length can be obtained with a streak camera, which was used to calibrate the response coefficients of the system. Bunch-by-bunch length can be measured by the multi-frequency harmonic analysis method from the button BPM  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW061  
About • paper received ※ 15 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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WEPGW064 Machine Learning Application in Bunch Longitudinal Phase Measurement network, synchrotron, damping, injection 2625
 
  • X.Y. Xu, Y.M. Zhou
    SINAP, Shanghai, People’s Republic of China
  • Y.B. Leng
    SSRF, Shanghai, People’s Republic of China
  
  High resolution bunch-by-bunch longitudinal phase measurement has been realized at Shanghai Synchrotron Radiation Facility (SSRF). In order to fully exploit the potency of the bunch phase monitor, the transient state during injection is being further studied. A longitudinal phase fitting method was used to study the synchrotron damping oscillation in injection events, where we can get the energy offsets between the injector and the storage ring, refilled bunch arrived time and the synchrotron damping time. However, manual multi-parameter fitting of nonlinear functions is awfully complex and slow. Machine learning algorithms, such as gradient descent and artificial neural network (ANN) is more suitable to do this fitting. Through these methods, we can quickly obtain more accurate fitting parameters and further realize online measurement of the refilled charge arrived time, energy offsets between the injector and storage ring, and the synchrotron damping time.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW064  
About • paper received ※ 13 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPRB009 Validation of the Series Power Couplers of the LIPAc SRF Linac operation, cryomodule, vacuum, linac 2811
 
  • H. Jenhani, N. Bazin, C. Boulch, S. Chel, G. Devanz, G. Disset, C. Servouin
    CEA-IRFU, Gif-sur-Yvette, France
  • I. Kirpitchev, J. Mollá, P. Méndez, D. Regidor, C. de la Morena
    CIEMAT, Madrid, Spain
  
  In the framework of the IFMIF/EVEDA project, the cryomodule of the Linear IFMIF Prototype Accelerator (LIPAc) will be assembled then tested at Rokkasho in 2019. Eight Series Power Couplers (PC) operating at 175 MHz were manufactured under a CEA contract, in order to equip this Cryomodule. They were all successfully RF conditioned up to 100 kW CW in TW and SW configurations. All the high RF power tests were performed under CIEMAT responsibility in BTESA Company premises, according to the CEA requirements. In order to fix difficulties encountered during the fab process, manufacturing and quality control have been analyzed in depth. Thanks to the corrective actions implemented, every PC reached the performances targeted for qualification. This paper will give details about this manufacturing phase and provide an overview of the obtained RF test results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB009  
About • paper received ※ 09 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB012 Overview on SC CH-Cavity Development cavity, linac, heavy-ion, status 2822
 
  • M. Busch, M. Basten, T. Conrad, P. Müller, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
  • W.A. Barth, F.D. Dziuba, M. Miski-Oglu
    GSI, Darmstadt, Germany
  • W.A. Barth, F.D. Dziuba, M. Miski-Oglu
    HIM, Mainz, Germany
  • W.A. Barth
    MEPhI, Moscow, Russia
  • F.D. Dziuba
    IKP, Mainz, Germany
  
  Funding: Work supported by GSI, HIC for FAIR, BMBF Contr. No. 05P18RFRB1
During the last decades an enermous effort has been put into the development of low beta structures for hadron acceleration worldwide. Since hadrons exhibit a very inert velocity gain due to their high mass this change in speed has to be taken into account when utilizing low beta cavities. At the Institute of Applied Physics (IAP), Frankfurt, Germany, five multi-cell CH-cavities (Crossbar H-Mode) have been developed and tested for different kind of applications so far. In addition to the successfully tested original 360 MHz prototype further structures envisaged for beam operation have been fabricated and tested. Overview, status and outlook of this cavity technology is topic of this contribution. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB012  
About • paper received ※ 08 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB015 Cleanroom Installations for SRF Cavities at the Helmholtz-Institut Mainz cavity, operation, vacuum, heavy-ion 2830
 
  • T. Kürzeder, K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, R.G. Heine, S. Lauber, J. List, M. Miski-Oglu
    HIM, Mainz, Germany
  • K. Aulenbacher, F.D. Dziuba
    IKP, Mainz, Germany
  • W.A. Barth, C. Burandt, V. Gettmann, M. Miski-Oglu, S. Yaramyshev
    GSI, Darmstadt, Germany
  • J. Conrad
    TU Darmstadt, Darmstadt, Germany
  • R.G. Heine, F. Hug, T. Stengler
    KPH, Mainz, Germany
  
  At the Helmholtz-Institut Mainz (HIM) a cleanroom has been equipped with new tools and installations for the planned treatment of different superconducting RF-cavities. At first TESLA/XFEL type 9-cell cavities for the Mainz Energy-Recovering Superconducting Accelerator (MESA) project or 217 MHz multigap Crossbar H-mode cavities for the HElmholtz LInear ACcelerator (HELIAC) under development by HIM and GSI will be treated. The cleanroom installations, including the greyroom, cover an area of about 155 sqm. In its ISO-class 6 area a large ultrasonic and a conductance rinsing bath has been installed recently. A high pressure rinsing cabinet (HPR) has been implemented between the ISO-class 6 and 4 cleanroom. A RF-cavity can be loaded and unloaded from both sides. HPR treatments are possible for cavities of up to 1.4 m length and about 0.7 m diameter. For drying the ISO-class 4 clean room is equipped with a 160 C vacuum oven. New cleanroom lifters allow the handling of up to 200 kg heavy objects. A rail system in the cleanroom floor is installed to move out the entire cold string of the cleanroom after assembly and leak testing. First operational experiences with this facility will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB015  
About • paper received ※ 29 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPRB016 Simulation of Quench Detection Algorithms for Helmholtz Zentrum Berlin SRF Cavities cavity, FPGA, LLRF, controls 2834
 
  • P. Echevarria, A. Neumann, A. Ushakov
    HZB, Berlin, Germany
  • B. Garcia
    UPV-EHU, Leioa, Spain
  • J. Jugo
    University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
  
  The Helmholtz Zentrum Berlin is carrying out two accelerator projects which make use of high gradient SRF cavities: BERLinPro* and BESSY-VSR**. In both projects, a prompt detection of a quench is crucial to avoid damages in the cryomodules and cavities themselves. In this paper, the response of real time estimation of the cavity parameters*** using the transmitted and forward RF signals is simulated, in order to perform the quench detection. The time response of the estimated half bandwidth is compared with the dissipated power in the cavity walls for the different type of SRF cavities used in both projects, i.e., BERLinPro’s photoinjector, booster and linac, and BESSY-VSR 1.5 GHz and 1.75 GHz cavities. As an intermediate step prior to the implementation in an mTCA.4 system together with the LLRF control and test with a real cavity, the algorithm has been implemented using a National Instruments FPGA board to check the its proper behavior.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB016  
About • paper received ※ 16 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPRB028 Electromagnetic Design of the Low Beta Cavities for the JAEA ADS cavity, linac, proton, superconductivity 2870
 
  • B. Yee-Rendón, Y. Kondo, F.M. Maekawa, S.I. Meigo, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  
  The Japan Atomic Energy Agency (JAEA) is designing a superconducting CW proton linear accelerator for the ADS project. The superconducting region will use five types of radio frequency cavities. In the region from 2 to 180 MeV the acceleration will be done using Half Wave Resonator (HWR) and Single Spokes (SS) cavities. HWR cavities will accelerate the beam from 2 to 10 MeV with a geometrical beta of 0.08 and the SS ones will do from 10 to 180 MeV using two cavity families with geometrical betas of 0.16 and 0.43. The results of electromagnetic model design are presented and the comparison with similar cavities from other projects are included.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB028  
About • paper received ※ 19 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB029 Design of the Elliptical Superconducting Cavities for the JAEA ADS cavity, superconducting-cavity, simulation, acceleration 2873
 
  • B. Yee-Rendón, Y. Kondo, F.M. Maekawa, S.I. Meigo, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  
  The superconducting CW proton linear accelerator for an Accelerator Driven Subcritical System (ADS) proposed by Japan Atomic Energy Agency (JAEA) employs elliptical cavities for the final acceleration of 180 MeV to 1.5 GeV. Since this energy region implies a change of beta from 0.55 to 1, two cavity models were developed using the geometrical betas of 0.68 and 0.89 to improve the acceleration efficiency. The study of the electromagnetic design was simulated using SUPERFISH (SF) code and python program to do variable scan, the results were benchmarked with CST Microwave Studio program (CST).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB029  
About • paper received ※ 18 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB031 SRF Trip Caused by the Tuner in BEPCII cavity, electron, operation, collider 2880
 
  • J.P. Dai, Z.H. Mi, P. Sha, Y. Sun, Q.Y. Wang, L.G. Xiao
    IHEP, Beijing, People’s Republic of China
  
  Funding: Work support by Natural Science Foundation of China (11575216)
The stability and reliability of the Superconducting RF system (SRF) is generally a key issue in a large scale accelerator such as Beijing Electron Positron Collider II (BEPCII). In the past several years, SRF is one of the main factors limiting the availability of BEPCII, and many efforts have been made to fix the SCRF troubles. This paper focuses on the details of the SCRF trip caused by the tuner, which is one of the most persistent troubles and figured out till the summer of 2018. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB031  
About • paper received ※ 08 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB065 Multi-physics Computation and Deformation Testing of a Shell-type 1.5-GHz Cavity cavity, experiment, resonance, synchrotron 2968
 
  • M.-C. Lin, C.H. Lo
    NSRRC, Hsinchu, Taiwan
  • M.-R. Lu, M.-K. Yeh
    NTHU, Hsinchu, Taiwan
  
  Funding: Work supported by the Ministry of Science and Technology, R. O. C. (Taiwan) under grant NSC-100-2628-E-213-001-MY3.
A copper prototype of a 1.5-GHz cavity was manufac-tured to simulate a superconducting radio-frequency cavity for technique development. Frequency tuning with longitudinal compression of this prototype and cryogenic cooling with liquid nitrogen were performed to examine the numerical results from finite-element models, mainly the corresponding shifts of the fundamental resonant frequency. An appropriate element option improved the accuracy of the resonant frequency and the distribution of the magnetic field. Effects of geometry distortion of an uneven length on the frequency shift of this shell-type cavity as loaded on longitudinal compression are also examined and discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB065  
About • paper received ※ 25 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB073 CW Room Temperature Accelerating Structures impedance, operation, electron, radiation 2990
 
  • S.P. Antipov, P.V. Avrakhov, E. Gomez, S.V. Kuzikov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
  
  To this day CW linear electron accelerators were based only on expensive and bulky (embedded in a cryostat) superconducting accelerating structures. CW regime can in principle be realized with normal conducting structures provided the shunt impedance is high. Such structures can be designed using dielectrics (ultra-pure ceramics in C-band and diamond in mm-waves) with ultra-low loss tangent (~10-6). The use of dielectrics allows to concentrate the electromagnetic energy density in the dielectric region and thus minimize fields and ohmic loss on metallic walls. The thermal loss in dielectric can be relatively low given the loss tangent is small. We report here the design of structures with shunt impedance on the order of 104 MOhm/m, which is several orders of magnitude higher than shut impedance in copper structures in GHz and THz range. High shunt impedance makes it possible to accelerate electrons to 1 MeV using kW-level CW RF sources like magnetrons in C-band and gyrotrons in THz range. Such CW accelerators will find applications in sterilization, food irradiation, industrial radiography and cargo inspection.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB073  
About • paper received ※ 21 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB087 High-gradient SRF Cavity R&D at Cornell University cavity, collider, linear-collider, vacuum 3017
 
  • M. Ge, T. Gruber, J.J. Kaufman, P.N. Koufalis, G. Kulina, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Achieving high accelerating field is a critical R&D topic for superconducting RF cavities for future accelerators including the International Linear collider (ILC). The ILC requires an average accelerating field of 35MV/m with a Q0 of at least 8.9·109 at 2K. In this paper, we report the latest results from high-gradient research at Cornell, which focusses on 75C vacuum baking to improve maximum (quench) fields. We demonstrate that such low temperature bakes can significantly improve quench fields in certain cases by mitigating localized defects. We further report on high-pulsed power results of these cavities before and after baking.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB087  
About • paper received ※ 23 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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WEPRB089 Theoretical Analysis of Quasiparticle Overheating, Positive Q-Slope, and Vortex Losses in SRF Cavities cavity, niobium, electron, experiment 3020
 
  • J.T. Maniscalco, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T. Arias, D. Liarte, J.P. Sethna, N. Sitaraman
    Cornell University, Ithaca, New York, USA
  
  The surface resistance of an SRF cavity is an important measure of its performance and utility: lower resistance leads directly to lower cryogenic losses and power consumption. This surface resistance comprises two components, namely the ‘‘BCS resistance’’, which depends strongly on the quasiparticle temperature, and a temperature-independent ‘‘residual resistance’’, which is often dominated by losses due to trapped magnetic vortices. Both components are generally dependent on the RF field strength. Here we present a summary of recent theoretical advances in understanding the microscopic mechanisms of the surface resistance, in particular addressing niobium hydride formation and quasiparticle overheating (using the tools of density functional theory) and discussing issues with existing models of the positive Q-slope, a field-dependent decrease in the BCS resistance, and possible paths for improvement of these models. We also discuss trapped flux losses using ideas from collective weak pinning theory.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB089  
About • paper received ※ 20 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB090 The Design of Parallel-Feed SC RF Accelerator Structure cavity, coupling, niobium, alignment 3024
 
  • M.H. Nasr, Z. Li, S.G. Tantawi, P.B. Welander
    SLAC, Menlo Park, California, USA
  
  Funding: Research funded by a SLAC Laboratory-Directed Research and Development award, supported by the U.S. Department of Energy, contract number DE-AC02-76SF00515
Development of superconducting RF (SRF) accelerator technology that enables both higher gradient and higher efficiency is crucial for future machines. While much of the recent R&D focus has been on materials and surface science, our aim is to optimize the cavity geometry to maximize performance with current materials. The recent demonstration of a highly efficient parallel-feed normal-conducting RF structure at SLAC has served as a proof-of-concept. Instead of coupled elliptical cells, the structure employs isolated re-entrant cells. To feed RF power to the cavities, each cell is directly coupled to an integrated manifold. The structure is made in two parts, split along the beam axis, which are then joined. Applied to SRF, simulations suggest such a structure could nearly double the achievable gradient, while reducing cryogenic RF loss by more than half. We are experimentally verifying the concept using an X-band SRF design to be tested at SLAC. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB090  
About • paper received ※ 24 May 2019       paper accepted ※ 27 May 2019       issue date ※ 21 June 2019  
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WEPRB094 Measurements of the Electrical Axes of the CeC PoP RF Cavities cavity, cathode, gun, electron 3031
 
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • Y.C. Jing, V. Litvinenko, J. Ma, I. Pinayev, K. Shih, G. Wang
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
  
  It is common knowledge that every mode in an SRF cavity has a so-called electrical axis, and only in an ideal cavity would this axis align exactly with the geometrical axis of the device. The misalignment of the electrical axis creates an additional undesirable transverse kick to the beam, which has to be corrected to achieve the designed beam parameters. In this paper we present the two methods which have been used in order to determine the electrical axes in the RF cavities of the Coherent electron Cooling (CeC) Proof of Principle (PoP) accelerator. The electron accelerator for the CeC PoP consists of the three main RF components: the 113 MHz SRF gun, the two normal-conducting 500 MHz bunching cavities, and the 704 MHz SRF 5-cell elliptical cavity. We discuss, in detail, the specifics of the measurement for each cavity and provide the corresponding results. In addition, we describe the influence of the field asymmetry in the 500 MHz bunchers on the beam dynamics, which was observed experimentally and confirmed by simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB094  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPRB098 Cryogenic RF Performance of Double-Quarter Wave Cavities Equipped with HOM Filters cavity, HOM, operation, cryogenics 3043
 
  • S. Verdú-Andrés, I. Ben-Zvi, Q. Wu, B.P. Xiao
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • G. Burt, J.A. Mitchell
    Lancaster University, Lancaster, United Kingdom
  • R. Calaga, O. Capatina
    CERN, Geneva, Switzerland
  • N.A. Huque, E.A. McEwen, H. Park, T. Powers
    JLab, Newport News, Virginia, USA
  • Z. Li, A. Ratti
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by US DOE through BSA LLC under contracts No. DE-AC02-98CH10886, No. DE-SC0012704, and the US LHC Accelerator Research Program (LARP) and by the EU HL-LHC Project.
Crab cavities are one of the several components included in the luminosity upgrade of the Large Hadron Collider (HL-LHC). The cavities have to provide a nominal deflecting kick of 3.4 MV per cavity while the cryogenic load per cavity stays below 5 W. Cold RF tests confirmed the required performances in bare cavities, with several cavities exceeding the required voltage by more than 50%. However, the first tests of a Double-Quarter Wave (DQW) cavity with one out of three HOM filters did not reach the required voltage. The present paper describes the studies and tests conducted on a DQW cavity with HOM filter to understand the limiting factor. The recipe to meet the performance specification and exceed the voltage requirement by more than 35% is discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB098  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB110 Recent Results from Nb3Sn-Coated Single-cell Cavities Combined with Sample Studies at Jefferson Lab cavity, experiment, superconductivity, niobium 3066
 
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G. Ciovati, G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • I.P. Parajuli
    ODU, Norfolk, Virginia, USA
  
  Funding: Partially authored by Jefferson Science Associates under contract no. DEAC0506OR23177. Supported by Office of High Energy Physics under grants DE-SC-0014475 and DE-SC-0018918.
The critical temperature (~ 18 K) and superheating field (~ 425 mT) of Nb3Sn are almost twice that of niobium, thereby promising the higher quality factor and accelerating gradient at any given temperature compared to traditional SRF cavities made of niobium. It can enable higher temperature for cavity operation (4 K Vs. 2 K), resulting in significant reduction in both capital and operating cost for the cryoplant. Several single-cell cavities along with witness samples were coated with Nb3Sn to explore, understand and improve the coating process for betterment of cavity performance. RF measurements of coated cavities combined with material characterization of witness samples were employed to update the coating process. Following some modifications to the existing coating process, we were able to produce Nb3Sn cavity with quality factor ≥ 2.1010 for accelerating gradient up to 15 MV/m at 4 K, without any significant Q-slope. In this article, we will discuss recent results from several Nb3Sn coated single-cell cavities combined with material studies of witness samples. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB110  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPRB114 Understanding and Pushing the Limits of Nitrogen Doping cavity, niobium, experiment, ECR 3078
 
  • D. Bafia, M. Checchin, A. Grassellino, M. Martinello, O.S. Melnychuk, S. Posen, A.S. Romanenko, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  • D. Bafia, J. Zasadzinski
    IIT, Chicago, Illinois, USA
  • D. Gonnella
    SLAC, Menlo Park, California, USA
  • A.D. Palczewski
    JLab, Newport News, Virginia, USA
  
  This work will describe Fermilab experiments that focus on the optimization of doping parameters to achieve low sensitivity to trapped magnetic flux while maintaining very high Q characteristic of nitrogen doped cavities and same or higher quench fields. Working partially in the context of LCLS-2 higher energy upgrade, new doping recipes are pursued and have been found to vary the mean free path of the resonator which is related to the sensitivity to trapped magnetic flux. Moreover, a correlation has been found between lighter doping and higher quench fields while maintaining sufficiently low surface resistance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB114  
About • paper received ※ 18 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS010 Beam Dynamics Errors Studies for the IFMIF-DONES SRF-LINAC linac, solenoid, cryomodule, cavity 3103
 
  • N. Chauvin, N. Bazin, J. Plouin
    CEA-DRF-IRFU, France
  • S. Chel, L. Du
    CEA-IRFU, Gif-sur-Yvette, France
  
  The goal of the IFMIF-DONES (International Fusion Materials Irradiation Facility-DEMO Oriented Neutron Source) project is to build an irradiation facility that will provide a sufficient neutron flux to study and characterize structure materials foreseen for future fusion power plant. In order to accelerate the required 125mA/40 MeV continuous deuteron beam from 5 MeV to 40 MeV, a superconducting radio-frequency (SRF) linac, housed in five cryomodules, is proposed. The design is based on two beta families (β=0.11 and β=0.17) of half-wave resonators (HWR) at 175MHz. The transverse focusing is achieved using one solenoid coil per focusing period. This paper presents the extensive multiparticle beam dynamics simulations that have been performed to adapt the beam along the SRF-linac in such a high space charge regime. As one of the constraints of the IFMIF linac is a low level of beam losses, specific optimizations have been done to minimize the beam occupancy in the line (halo). A Monte Carlo error analysis has also been carried out to study the effects of misalignments or field imperfections (static errors) and also vibrations or power supplies ripple (dynamic errors). The results of these errors studies are presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS010  
About • paper received ※ 21 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPMP013 Challenges Towards Industrialization of the ERL-FEL Light Source for EUV Lithography FEL, cavity, cathode, undulator 3478
 
  • N. Nakamura, E. Kako, R. Kato, H. Kawata, T. Miyajima, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
  
  EUV Lithography is going to HVM (high volume manufacturing) stage with 250-W-class laser-produced plasma sources and it is important to develop a new-type EUV light source to meet future demand for higher power. Energy-recovery linac based free-electron lasers (ERL-FELs) are possible candidates of a high-power EUV light source that can distribute 1 kW power to multiple scanners simultaneously. In Japan, an ERL-FEL based EUV light source has been designed using available technologies without much development to demonstrate generation of EUV power more than 10 kW and the EUV-FEL Light Source Study Group for Industrialization has been established since 2015 to realize industrialization of the light source and the related items. For industrialization, high availability is essential as well as high power and reduction of the light source size is also required. In this paper, we will report an overview of the designed ERL-FEL light source for EUV lithography and some activities for the industrialization and describe considerations and developments for obtaining high availability and size reduction of the light source.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP013  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPMP048 Mu*STAR: A Modular Accelerator-Driven Subcritical Reactor Design site, neutron, target, operation 3555
 
  • R.P. Johnson, R.J. Abrams, M.A. Cummings, J.D. Lobo, M. Popovic, T.J. Roberts
    Muons, Inc, Illinois, USA
  
  Mu*STAR is an accelerator-driven molten-salt sub-critical reactor based on recent superconducting RF technological breakthroughs that allow a highly efficient and powerful proton accelerator to drive a spallation target inside a graphite-moderated, thermal-spectrum reactor. The additional spallation neutrons can be used to overcome the absorption of neutrons by fission products to allow a deeper burn than is possible with critical reactor designs. Simulations have shown that as much as seven times the energy that was extracted from used fuel from light water reactors can be produced by this method before the accelerator demands significant power from the reactor. Once the fuel rods have been converted from oxide ceramics to fluoride salts, in a process that is proliferation resistant (not chemical reprocessing), the fuel can be burned for centuries without increasing its volume while reducing its radio-toxicity. Our 2017 GAIN voucher grant supported studies by ORNL, SRNL, and INL to design and cost a Fuel Processing Plant to convert used nuclear fuel into the molten-salt fuel for Mu*STAR. Based on those studies, it seems possible to build Mu*STAR systems on existing sites where used fuel is stored, convert it to fluoride salts, and use it to provide affordable carbon-free electricity for centuries.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP048  
About • paper received ※ 19 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB007 Ponderomotive Instability of Self-Excited Cavity cavity, resonance, feedback, controls 3808
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
  
  The electro-magnetic fields within a super-conducting radio frequency (SRF) cavity can be sufficiently strong to deform the cavity shape, which may lead to a ponderomotive instability. Stability criteria for the self-excited mode of cavity operation were given in 1978 by Delayen. The treatment was based on the Routh-Hurwitz analysis of the characteristic polynomial. With the Wolfram modern analytical tool, "Mathematica", we revisit the criteria for an SRF cavity equipped with amplitude and phase loops and a single microphonic mechanical mode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB007  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPRB010 Ponderomotive Instability of Generator-Driven Cavity cavity, resonance, controls, feedback 3820
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
  
  The electro-magnetic fields within a super-conducting radio frequency (SRF) cavity can be sufficiently strong to deform the cavity shape, which may lead to a ponderomotive instability. Stability criteria for the generator-driven mode of cavity operation were given in 1971 by Schulze. The treatment side-stepped the Routh-Hurwitz analysis of the characteristic polynomial. With the Wolfram modern analytical tool, ’Mathematica’, we revisit the criteria for an SRF cavity equipped with amplitude and phase loops and a single microphonic mechanical mode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB010  
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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THPRB093 RF Data Acquisition and Soft Alarm System for the Taiwan Photon Source EPICS, status, network, data-acquisition 4039
 
  • Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.T. Li, M.-C. Lin, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
  
  The Taiwan Photon Source (TPS) is a modern, high brightness 3 GeV light source. A data acquisition pro-gram for the radio frequency (RF) system, including a transient data recorder, a long term data archiver and real time data monitoring, has been developed for the analysis of RF trips and RF system debugging. A soft alarm system is implemented as well utilizing EPICS and python packages. The hardware architecture and the functionality of the RF data acquisition and soft alarm system will be discussed in this article.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB093  
About • paper received ※ 09 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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