Author: Rimmer, R.A.
Paper Title Page
MOPMB078 Design and Prototyping of the Electron Ion Collider Electron Storage Ring SRF Cavity 293
 
  • J. Guo, E.F. Daly, E. Drachuk, R.R. Fernandes, J. Henry, J. Matalevich, G.-T. Park, R.A. Rimmer, D. Savransky
    JLab, Newport News, Virginia, USA
  • D. Holmes, K.S. Smith, W. Xu, A. Zaltsman
    BNL, Upton, New York, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
Among the EIC¿s numerous RF subsystems, the electron storage ring¿s (ESR) 591 MHz fundamental RF system is one of the most challenging. Each cavity in the system will handle up to 2.5 A of beam current and supply up to 600 kW beam power under a wide range of voltage. The EIC R&D plan includes the design, fabrication and testing of such a cavity. In this paper, we will report the latest status and findings of the ongoing design and prototyping of this cavity, including the RF and mechanical/thermal design, fabrication design, and the progress of fabrication.
 
poster icon Poster MOPMB078 [1.489 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB078  
About • Received ※ 12 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 28 June 2023 — Issue date ※ 19 July 2023
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TUCAA02
EIC Project Overview and Related SRF Technologies  
 
  • E.F. Daly, J. Guo, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • Z.A. Conway, D. Holmes, Q. Wu, B.P. Xiao, W. Xu, A. Zaltsman
    BNL, Upton, New York, USA
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • K.S. Smith
    Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
 
  Funding: This is authored by Jefferson Science Associate, LLC under U. S. DOE Contract No. DE-AC05-06OR23177.
The Electron-Ion Collider (EIC), with a range of center-of-mass energies from 20 to 140 GeV, will enable experimental nuclear physics in the gluon-dominated regime with luminosity up to 1034 cm2 per second. The project chose to employ SRF technology for several accelerating and crab cavity geometries used throughout the accelerator complex to achieve the EIC¿s energy and luminosity goals. This presentation will review the current status of the EIC, the SRF technology used in the accelerator complex and current status of SRF R&D. The discussion will share EIC’s fundamental high-power coupler design & performance, high-power HOM power handling hardware, SRF elliptical and crab cavity designs and recent experimental results.
 
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TUPTB010 Preservation of the High Quality Factor and Accelerating Gradient of Nb₃Sn-Coated Cavity During Pair Assembly 405
 
  • G.V. Eremeev, S. Cheban, S. Posen, B. Tennis
    Fermilab, Batavia, Illinois, USA
  • J.F. Fischer, D. Forehand, U. Pudasaini, A.V. Reilly, R.A. Rimmer
    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.
Two CEBAF 5-cell accelerator cavities have been coated with Nb₃Sn film using the vapor diffusion technique. One cavity was coated in the Jefferson Lab Nb₃Sn cavity coating system, and the other in the Fermilab Nb₃Sn coating system. Both cavities were measured at 4 K and 2 K in the vertical dewar test in each lab and then assembled into a cavity pair at Jefferson Lab. Previous attempts to assemble Nb₃Sn cavities into a cavity pair degraded the superconducting properties of Nb₃Sn-coated cavities. This contribution discusses the efforts to identify and mitigate the pair assembly challenges and will present the results of the vertical tests before and after pair assembly. Notably, one of the cavities reached the highest gradient above 80 mT in the vertical test after the pair assembly.
 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB010  
About • Received ※ 23 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 02 July 2023 — Issue date ※ 09 July 2023
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TUPTB033 On the Way to a 10 MeV, Conduction-Cooled, Compact SRF Accelerator 471
 
  • H. Vennekate, G. Cheng, G. Ciovati, J. Guo, K.A. Harding, J. Henry, U. Pudasaini, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • A. Castilla
    JLAB, Newport News, USA
  • F.E. Hannon
    Phase Space Tech, Bjärred, Sweden
  • D.A. Packard
    GA, San Diego, California, USA
  • J. Rathke
    TechSource, Los Alamos, New Mexico, USA
  • T. Schultheiss
    TJS Technologies, Commack, New York, USA
 
  Funding: The presentation has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
After the success of designing a compact 1 MeV, 1 MW accelerator based on conduction-cooled SRF, Jefferson Lab is now pursuing a concept to provide a tenfold increase of the beam energy. The higher energy significantly extends the range of applications for environmental remediation and industry in general. The obvious challenge for SRF is to move from a single-cell to a multicell cavity while maintaining high efficiency and the ability to operate the machine without a complex cryogenic plant. The contribution presents the latest results of this design study with respect to its centerpiece, a Nb₃Sn coated 915 MHz five-cell cavity and its corresponding RF components, i.e. FPC and HOM absorber, as well as the conduction-cooling concept based on commercially available cryocoolers.
 
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB033  
About • Received ※ 19 June 2023 — Revised ※ 24 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023
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TUPTB068 EIC 197 MHz Crab Cavity RF Optimization 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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WEPWB047 Higher Order Mode Analysis of a 915 MHz 2-Cell Cavity for a Prototype Industrial Accelerator 667
 
  • A. Castilla
    JLAB, Newport News, USA
  • G. Ciovati, J. Guo, G.-T. Park, R.A. Rimmer, H. Vennekate
    JLab, Newport News, VA, USA
 
  A possible solution to reduce the complexity posed by the cryogenic systems in a superconducting RF accelerator for industrial applications, is to capitalize on the advances achieved by the Nb₃Sn superconducting RF technology, as well as the feasibility of a reliable 4 K cooling system, based on commercial cryocoolers. Following this philosophy, the conceptual design for a prototype, conduction-cooled, 4 MeV, 20 kW SRF electron linac, is being developed at Jefferson Lab. Such design is based on a 915 MHz two-cell Nb₃Sn cavity. In this contribution, we present the proposed cavity design, including the fundamental power coupler, and the preliminary analysis of the Higher Order Modes, using numerical simulations to estimate the potentially dangerous modes as a starting point to evaluate the requirements for damping for reliable operations with a cryocooler. Finally, different methods to calculate the Higher Order Modes’ Impedances are briefly discussed.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB047  
About • Received ※ 25 June 2023 — Revised ※ 29 June 2023 — Accepted ※ 04 July 2023 — Issue date ※ 16 July 2023
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WEPWB049 Multipacting in C75 Cavities 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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WEPWB089 Theoretical Model of External Q Tuning for an SRF Cavity with Waveguide Tuner 794
 
  • W. Xu, Z.A. Conway, K.S. Smith, A. Zaltsman
    BNL, Upton, New York, USA
  • E.F. Daly, J. Guo, R.A. Rimmer
    JLab, Newport News, Virginia, USA
 
  Funding: The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
A wide range of electron beam energies (5 ¿ 18 GeV) and beam currents (0.2 ¿ 2.5 A) in EIC Electron Storage Ring (ESR) operating scenarios requires a capability of adjusting coupling factor up to a factor of 20 for the 591 MHz Superconducting Radio Frequency (SRF) cavities, which contains two fundamental power couplers (FPC) delivering continuous wave (CW) 800 kW RF power to the beam. Currently, adjusting external Q of a SRF cavity is done by varying protrusion of FPC¿s inner conductor in beam pipe or using three stub tuner to adjust external Q value, which either has limit on tuning range or limit on operating power. This paper presents a method of tuning the FPC external Q by a multiple-waveguide tuner, which allows for high power, wide tuning range operations. The theoretical model of matching beam impedance with waveguide tuner and detailed matching conditions and limits will be presented. Follow the theoretical model, a preliminary design of a 3D waveguide tuner will be presented.
The work is supported by by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
 
poster icon Poster WEPWB089 [1.269 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB089  
About • Received ※ 26 June 2023 — Revised ※ 27 June 2023 — Accepted ※ 19 August 2023 — Issue date ※ 22 August 2023
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WEPWB103 Simulations and First RF Measurements of Coaxial HOM Coupler Prototypes for PERLE SRF Cavities 831
 
  • C. Barbagallo, P. Duchesne, W. Kaabi, G. Olivier, G. Olry, S. Roset, Z.F. Zomer
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • B.S. Barriere, C.S. Clement, R.L.A. Gerard, F. Gerigk, P.M. Maurin
    CERN, Meyrin, Switzerland
  • J. Henry, S.A. Overstreet, G.-T. Park, R.A. Rimmer, H. Wang
    JLab, Newport News, Virginia, USA
 
  Superconducting Radio-Frequency (SRF) linac cryomodules are foreseen for the high-current multi-turn energy recovery linac PERLE (Powerful Energy Recovery Linac for Experiments). Coaxial higher order mode (HOM) couplers are the primary design choice to absorb beam-induced power and avoid beam instabilities. We have used 3D-printed and copper-coated HOM couplers for the prototyping and bench RF measurements on the copper PERLE cavities. We have started a collaboration with JLab and CERN on this effort. This paper presents electromagnetic simulations of the cavity HOM-damping performance on those couplers. Bench RF measurements of the HOMs on an 801.58 MHz 2-cell copper cavity performed at JLab are detailed. The results are compared to eigenmode simulations in CST to confirm the design. RF-thermal simulations are conducted to investigate if the studied HOM couplers undergo quenching.  
poster icon Poster WEPWB103 [1.533 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB103  
About • Received ※ 18 June 2023 — Revised ※ 26 June 2023 — Accepted ※ 29 June 2023 — Issue date ※ 02 July 2023
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WEPWB131 Demonstration of Magnetron as an Alternative RF Source for SRF Accelerators 902
 
  • H. Wang, K. Jordan, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • J.P. Anderson, C.P. Moeller, K.A. Thackston
    GA, San Diego, California, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and DOE OS/ARDAP Accelerator Stewardship award 2019-2023.
Magnetron has been considered as alternate high-efficiency, low-cost RF sources for linacs and storage rings [1] for national labs and industrial applications. After the demonstration of magnetrons power to drive and combine for a radio frequency cavity at 2450 MHz in CW mode, we have used trim coils adding to a water-cooled magnetron and amplitude modulation feedback to further suppress the side-band noise to -46.7 dBc level. We also demonstrated the phase-locking to an industrial grade cooking magnetron transmitter at 915 MHz with a 75 kW CW power delivered to a water load by using a -26.6 dBc injection signal [2]. The sideband noise from the 3-Phase SCRs DC power supply can be reduced to -16.2 dBc level. Further noise reduction and their power combining scheme using magic-tee and cavity type combiners for higher power application (2x75kW) are to be presented. We intent to use one power station to drive the normal conducting and superconducting RF cavities for the inductrial linac. We also going to demonstarte a vertical SRF cavity test with a high input coupling Q using a 2.45GHz magnetron and comparing with a baseline test result using a solid state amplifier.
[1]. doi:10.18429/JACoW-IPAC2015-WEPWI028.
[2]. doi:10.18429/JACoW-NAPAC2022-WEZD3.
 
poster icon Poster WEPWB131 [2.445 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2023-WEPWB131  
About • Received ※ 16 June 2023 — Revised ※ 28 June 2023 — Accepted ※ 30 June 2023 — Issue date ※ 19 August 2023
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THIXA04
Development of a Prototype Superconducting Radio-Frequency Cavity for Conduction-Cooled Accelerators  
 
  • G. Ciovati, S. Balachandran, G. Cheng, E.F. Daly, P. Dhakal, K.A. Harding, F. Marhauser, T. Powers, U. Pudasaini, R.A. Rimmer, H. Vennekate
    JLab, Newport News, VA, USA
  • J.P. Anderson, B.R.L. Coriton, L.D. Holland, K.R. McLaughlin, D.A. Packard, D.M. Vollmer
    GA, San Diego, California, USA
  • A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • J. Rathke
    TechSource, Los Alamos, New Mexico, USA
  • T. Schultheiss
    TJS Technologies, Commack, New York, USA
 
  Funding: Work supported by the U.S. DOE, ARDAP Office, under contract No. DE-AC05-06OR23177. SB¿s microscopy work at the NHMFL was partly supported by the U.S. DOE, HEP Office under Award No. DE-SC0009960.
Recent progress in the development of high-quality Nb₃Sn film coatings along with the availability of cryocoolers with high cooling capacity at 4 K makes it feasible to operate SRF cavities cooled by thermal conduction at relevant accelerating gradients for use in accelerators. We have developed a prototype single-cell cavity to prove the feasibility of operation up to the accelerating gradient required for 1 MeV energy gain, cooled by conduction with cryocoolers. The cavity has a ~3 ¿m thick Nb₃Sn film on the inner surface, deposited on a ~4 mm thick bulk Nb substrate and a bulk ~7 mm thick Cu outer shell with three Cu attachment tabs. The cavity was tested up to a peak surface magnetic field of 53 mT in liquid He at 4.3 K. A horizontal test cryostat was designed and built to test the cavity cooled with three cryocoolers. The rf tests of the conduction-cooled cavity achieved a peak surface magnetic field of 50 mT and stable operation was possible with up to 18.5 W of rf heat load. The peak frequency shift due to microphonics was 23 Hz. These results represent the highest peak surface magnetic field achieved in a conduction-cooled SRF cavity to date
 
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