Keyword: multipactoring
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MOPMB030 Medium Temperature Furnace Baking of Low-beta 650 MHz Five-cell Cavities cavity, niobium, radio-frequency, SRF 158
 
  • G. Wu, S.K. Chandrasekaran, V. Chouhan, G.V. Eremeev, F. Furuta, K.E. McGee, A.A. Murthy, A.V. Netepenko, J.P. Ozelis, H. Park, S. Posen
    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.
Medium Temperature baking of low beta 650 MHz cavities was conducted in a UHV furnace. A systematic study of cavity surface resistance components, residual and BCS, was conducted, including analyzing surface resistance due to trapped magnetic flux. Cavities showed an average 4.5 nano-ohm surface resistance at 17 MV/m under 2 K, which meets PIP-II specifications with a 40% margin. The results provided helpful information for the PIP-II project to optimize the cavity processing recipe for cryomodule application. The results were compared to the 1.3 GHz cavity that received a similar furnace baking.
 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB030  
About • Received ※ 19 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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MOPMB063 Multipacting Processing in Cryomodules for LCLS-II and LCLS-II-HE cavity, cryomodule, linac, radiation 259
 
  • A.T. Cravatta, T.T. Arkan, D. Bafia, J.A. Kaluzny, S. Posen
    Fermilab, Batavia, Illinois, USA
  • S. Aderhold, M. Checchin, D. Gonnella, J. Hogan, J.T. Maniscalco, J. Nelson, R.D. Porter, L.M. Zacarias
    SLAC, Menlo Park, California, USA
  • M.A. Drury, H. Vennekate
    JLab, Newport News, Virginia, 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.
Multipacting (MP) is a phenomenon which can affect stability in particle accelerators and limit performance in superconducting radio frequency cavities. In the TESLA shaped, 1.3 GHz, 9-cell cavities used in the LCLS-II (L2) and LCLS-II-HE (HE) projects, the MP-band (~17-24 MV/m) lies within the required accelerating gradients. For HE, the operating gradient of 20.8 MV/m lies well within the MP-band and cryomodule testing has confirmed that this is an issue. As such, MP processing for the HE cryomodule test program will be discussed. Early results on MP processing in cryomodules installed in the L2 linac will also be presented, demonstrating that the methods used in cryomodule acceptance testing are also successful at conditioning MP in the accelerator and that this processing is preserved in the mid-term.
 
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DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB063  
About • Received ※ 25 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 30 June 2023
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TUPTB001 Demonstration of Niobium Tin in 218 MHz Low-Beta Quarter Wave Accelerator Cavity cavity, niobium, SRF, vacuum 388
 
  • T.B. Petersen, G. Chen, B.M. Guilfoyle, M. Kedzie, M.P. Kelly, T. Reid
    ANL, Lemont, Illinois, USA
  • G.V. Eremeev, S. Posen, B. Tennis
    Fermilab, Batavia, Illinois, USA
 
  A 218 MHz quarter wave niobium cavity has been fabricated for the purpose of demonstrating Nb₃Sn technology on a low-beta accelerator cavity. Niobium-tin has been established as a promising next generation SRF material, but development has focused primarily in high-beta elliptical cell cavities. This material has a significantly higher TC than niobium, allowing for design of higher frequency quarter wave cavities (that are subsequently smaller) as well as for significantly lowered cooling requirements (possibly leading to cryocooler based de-signs). The fabrication, initial cold testing, and Nb₃Sn coating are discussed as well as test plans and details of future applications.  
poster icon Poster TUPTB001 [0.653 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB001  
About • Received ※ 16 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 27 June 2023 — Issue date ※ 08 July 2023
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TUPTB035 Design, Fabrication, and Test of a 175 MHz, β = 0.18, Half Wave Resonator for the IFMIF-DONES SRF-Linac cavity, SRF, linac, target 477
 
  • J. Plouin, M. Baudrier, S. Chel, G. Devanz, A. Madur, L. Maurice, C. Servouin
    CEA-DRF-IRFU, France
  • N. Bazin, G. Jullien
    CEA-IRFU, Gif-sur-Yvette, France
 
  The IFMIF-DONES facility will serve as a fusion-like neutron source for the assessment of materials damage in future fusion reactors. The neutron flux will be generated by the interaction between the lithium curtain and the deuteron beam from an RF linear accelerator at 40 MeV and nominal CW current of 125 mA. The last accelerating stage is a superconducting (SRF) Linac hosting five cryomodules. This SRF-Linac is equipped of two types of 175 MHz half wave superconducting cavities (HWRs). The first type of cavities (cryomodules 1 and 2), characterized by beta equal to 0.11, have been studied and qualified in the frame of IFMIF/EVEDA project. The development of the second type of cavities (cryomodules 3, 4 and 5), with higher beta of 0.18 is presented in this paper. A prototype has been designed, fabricated and tested in a vertical cryostat at CEA. The measured quality factor at nominal accelerating field (4.5 MV/m) is 2.3 109 and keeps higher than 109 up to 10 MV/m, which gives confidence in the cavity design and preparation to reach the expected performances after integration in the SRF linac.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB035  
About • Received ※ 20 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 15 July 2023
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TUPTB066 Fabrication and Testing of a Prototype RF-Dipole Crabbing Cavity cavity, dipole, collider, electron 573
 
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • H. Park
    Fermilab, Batavia, Illinois, USA
 
  Crabbing cavities are essential in particle colliders to compensate the luminosity degradation due to beam collision at a crossing angle. The 952.6 MHz 2-cell rf-dipole crabbing cavity system was proposed for the Jef-ferson Lab Electron-Ion Collider to restore the head-on collisions of electron and proton bunches at the interac-tion point. A prototype cavity was designed and devel-oped to demonstrate the performance of multi-cell rf-dipole structures. This paper presents the fabrication pro-cess and cold test results of the first 2-cell rf-dipole proto-type cavity.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB066  
About • Received ※ 18 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 21 August 2023
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TUPTB068 EIC 197 MHz Crab Cavity RF Optimization cavity, HOM, GUI, impedance 584
 
  • Z. Li
    SLAC, Menlo Park, California, USA
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • Q. Wu, B.P. Xiao, W. Xu
    BNL, Upton, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under U.S. DOE K No. DE-SC0012704, by Jefferson Science Associates, LLC under U.S. DOE K No. DE-SC0002769, and by DOE K No. DE-AC02-76SF00515.
Crab cavities, operating at 197 MHz and 394 MHz respectively, will be used to compensate the loss of luminosity due to a 25 mrad crossing angle at the interaction point in the Electron Ion Collider (EIC). Both crab cavities are of the RF Dipole (RFD) shape. To meet the machine design requirements, there are a few important cavity design considerations that need to be addressed. First, to achieve stable cavity operation at the design voltages, cavity geometry details must be optimized to suppress potential multipacting. Incorporating strong HOM damping in the cavity design is required for the beam stability and quality. Furthermore, due to the finite pole width, the multipole fields, especially the sextupole and the decapole terms, need to be minimized to maintain an acceptable beam dynamic aperture. This paper will present the RF optimization details of the 197 MHz cavity.
 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB068  
About • Received ※ 16 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 03 July 2023 — Issue date ※ 08 July 2023
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WEPWB049 Multipacting in C75 Cavities cavity, electron, simulation, SRF 674
 
  • G. Ciovati, P. Dhakal, R.A. Rimmer, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: This work was supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Cavities for the C75 cryomodule refurbishment program are currently being built, processed, tested and installed in the CEBAF accelerator at Jefferson Lab. They consist of 5-cell, 1497 MHz cavities with waveguide-type power coupler and for higher-order modes. Most of the cavities rf tests in a vertical cryostat at 2.07 K were limited by strong multipacting at accelerating gradients in the range 18 - 23 MV/m. A softer multipacting barrier was sometimes found at 13 - 15 MV/m. An unusual feature of the multipacting was that the barrier often shifted to a lower gradient ~17 MV/m, after multiple quenches at ~20 MV/m. This phenomenon was reproduced in a single-cell cavity of the same shape. The cavity was tested after different amounts of mechanical tuning and residual magnetic field, with no significant impact to the multipacting behavior. This contribution summarizes the experimental results from cavity rf tests, some of which were complemented by additional diagnostic instrumentation. Results from 2D and 3D simulations are also presented, indicating favorable conditions for multipacting at the equator in the range 20 - 29 MV/m.
 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB049  
About • Received ※ 15 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 01 July 2023
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WEPWB104 RF Conditioning of MYRRHA Couplers at IJCLab vacuum, electron, cavity, FEL 835
 
  • N. ElKamchi, S. Berthelot, P. Duchesne, C. Joly, W. Kaabi, C. Magueur
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • Y. Gómez Martínez
    LPSC, Grenoble Cedex, France
  • C. Lhomme
    IJCLab, ORSAY, France
 
  Multi-purpose hYbrid Research Reactor for High-tech Applications (MYRRHA) is an experimental accelerator-driven system in development at SCK•CEN. It will allow fuel developments, material developments for GEN IV systems, material developments for fusion reactors and radioisotope production for medical and industrial applications1. The IJCLab has in charge the industrial monitoring, the quality control and the RF conditioning of the power couplers up to 80KW at 352Mhz. This paper presents the conditioning bench adapted from the successful experience of IJCLab in the conditioning of the XFEL couplers2. The results of the conditioning of prototype couplers are described and discussed.
1. Abderrahim, P. MYRRHA a multi-purpose hybrid research reactor for high-tech applications. United States: N. p., 2012. Web
2. H. Guler, Proceedings of IPAC2016, Busan, Korea
 
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DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB104  
About • Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 08 August 2023
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WEPWB105 Improved Study of the Multipactor Phenomenon for the MYRRHA 80 kW CW RF Couplers electron, coupling, linac, cavity 838
 
  • Y. Gómez Martínez, P.-O. Dumont
    LPSC, Grenoble Cedex, France
  • P. Duchesne, N. ElKamchi, C. Joly, W. Kaabi
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • C. Lhomme
    IJCLab, ORSAY, France
  • C. Lhomme
    ACS, Orsay, France
 
  MYRRHA (Multi Purpose Hybrid Reactor for High Tech Applications) is an Accelerator Driven System (ADS) project. Its superconducting linac will provide a 600 MeV - 4 mA proton beam. The first project phase based on a 100 MeV linac is launched. The Radio-Frequency (RF) couplers have been designed to handle 80 kW CW (Continuous Wave) at 352.2 MHz. This paper describes the multipactor studies on the coupler when it does not work in the nominal configuration without reflected power.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB105  
About • Received ※ 18 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 12 July 2023
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