Author: Kelly, M.P.
Paper Title Page
MOPA22 Study on Electropolishing Conditions for 650 MHz Niobium SRF Cavity 97
 
  • V. Chouhan, D.J. Bice, F. Furuta, M. Martinello, M.K. Ng, H. Park, T.J. Ring, G. Wu
    Fermilab, Batavia, Illinois, USA
  • B.M. Guilfoyle, M.P. Kelly, T. Reid
    ANL, Lemont, Illinois, USA
 
  The PIP II linear accelerator includes different types of niobium SRF cavities including 650 MHz elliptical low (0.61) and high (0.92) beta cavities. The elliptical cavity surface is processed with the electropolishing method. The elliptical cavities especially the low-beta 650 MHz cavities showed a rough equator surface after the EP was performed with the standard EP conditions. This work was focused to study the effect of different EP parameters, including cathode surface area, temperature and voltage, and optimize them to improve the cavity surface.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA22  
About • Received ※ 02 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 03 September 2022
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MOPA85 Design of a 185.7 MHz Superconducting RF Photoinjector Quarter-Wave Resonator for the LCLS-II-HE Low Emittance Injector 245
 
  • S.H. Kim, W. Hartung, T. Konomi, S.J. Miller, M.S. Patil, J.T. Popielarski, K. Saito, T. Xu, T. Xu
    FRIB, East Lansing, Michigan, USA
  • C. Adolphsen, L. Ge, F. Ji, J.W. Lewellen, L. Xiao
    SLAC, Menlo Park, California, USA
  • M.P. Kelly, T.B. Petersen, P. Piot
    ANL, Lemont, Illinois, USA
  • P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy Contract DE-AC02-76SF00515.
A 185.7 MHz superconducting quarter-wave resonator (QWR) was designed for the low emittance injector of the Linac Coherent Light Source high energy upgrade (LCLS-II-HE). The cavity was designed to minimize the risk of cathode efficiency degradation due to multipacting or field emission and to operate with a high RF electric field at the cathode for low electron-beam emittance. Cavity design features include: (1) shaping of the cavity wall to reduce the strength of the low-field coaxial multipacting barrier; (2) four ports for electropolishing and high-pressure water rinsing; and (3) a fundamental power coupler (FPC) port located away from the accelerating gap. The design is oriented toward minimizing the risk of particulate contamination and avoid harmful dipole components in the RF field. The ANL 162 MHz FPC design for PIP-II is being adapted for the gun cavity. We will present the RF design of the cavity integrated with the FPC.
 
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA85  
About • Received ※ 03 August 2022 — Revised ※ 09 August 2022 — Accepted ※ 11 August 2022 — Issue date ※ 30 August 2022
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MOPA87 Design of the Cathode Stalk for the LCLS-II-HE Low Emittance Injector 253
 
  • T. Konomi, W. Hartung, S.H. Kim, S.J. Miller, D.G. Morris, J.T. Popielarski, K. Saito, A. Taylor, T. Xu
    FRIB, East Lansing, Michigan, USA
  • C. Adolphsen, J.W. Lewellen
    SLAC, Menlo Park, California, USA
  • S. Gatzmaga, P. Murcek, R. Xiang
    HZDR, Dresden, Germany
  • M.P. Kelly, T.B. Petersen
    ANL, Lemont, Illinois, USA
 
  Superconducting radio-frequency (SRF) electron guns are attractive for delivery of beams at a high bunch repetition rate with a high accelerating field. An SRF gun is the most suitable injector for the high-energy upgrade of the Linac Coherent Light Source (LCLS-II-HE), which will produce high-energy X-rays at high repetition rate. An SRF gun is being developed for LCLS-II-HE as a collaborative effort by FRIB, HZDR, ANL, and SLAC. The cavity operating frequency is 185.7 MHz, and the target accelerating field at the photocathode is 30 MV/m. The photocathode is replaceable. The cathode is held by a fixture (’cathode stalk’) that is designed for thermal isolation and particle-free cathode exchange. The stalk must allow for precise alignment of the cathode position, cryogenic or room-temperature cathode operating temperature, and DC bias to inhibit multipacting. We are planning a test of the stalk to confirm that the design meets the requirements for RF power dissipation and biasing. In this presentation, we will describe the cathode stalk design and RF/DC stalk test plan.  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-MOPA87  
About • Received ※ 04 August 2022 — Revised ※ 11 August 2022 — Accepted ※ 18 August 2022 — Issue date ※ 11 September 2022
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WEPA03 Status of the SLAC/MSU SRF Gun Development Project 623
 
  • J.W. Lewellen, C. Adolphsen, R. Coy, L. Ge, F. Ji, M.J. Murphy, L. Xiao
    SLAC, Menlo Park, California, USA
  • A. Arnold, S. Gatzmaga, P. Murcek, R. Xiang
    HZDR, Dresden, Germany
  • Y. Choi, C. Compton, X.-J. Du, D.B. Greene, W. Hartung, S.H. Kim, T. Konomi, S.J. Miller, D.G. Morris, M.S. Patil, J.T. Popielarski, L. Popielarski, K. Saito, T. Xu
    FRIB, East Lansing, Michigan, USA
  • M.P. Kelly, T.B. Petersen
    ANL, Lemont, Illinois, USA
 
  Funding: US Department of Energy.
The LCLS-II-HE project at SLAC is intended to increase the photon energy reach of the LCLS-II FEL to at least 20 keV. In addition to upgrading the undulator system, and increasing the electron beam energy to 8 GeV, the project will also construct a low-emittance injector (LEI) in a new tunnel. To achieve the LEI emittance goals, a low-MTE photocathode will be required, as will on-cathode electric fields up to 50% higher than those achievable in the current LCLS-II photoinjector. The beam source for the LEI will be based around a superconducting quarterwave cavity resonant at 185.7 MHz. A prototype gun is currently being designed and fabricated at the Facility for Rare Isotope Beams (FRIB) at Michigan State University. This paper presents the performance goals for the new gun design, an overview of the prototype development effort, current status, and future plans including fabrication of a "production" gun for the LEI.
 
poster icon Poster WEPA03 [4.510 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-NAPAC2022-WEPA03  
About • Received ※ 21 July 2022 — Revised ※ 28 July 2022 — Accepted ※ 08 August 2022 — Issue date ※ 11 August 2022
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THZD2
Advances in the ATLAS Accelerator  
 
  • M.P. Kelly, C. Dickerson, B.M. Guilfoyle, M.R. Hendricks, M. Kedzie, T.B. Petersen, T. Reid
    ANL, Lemont, Illinois, USA
 
  Funding: DOE-NP
The ATLAS Superconducting Linac at Argonne National Laboratory is a leading facility for nuclear reaction and structure studies, providing ion beams over the full mass range to a community of users from the US and abroad. The technology of ATLAS has been continuously upgraded since commissioning in 1978 and has remained at the forefront of superconducting linac development, especially for low-beta Linacs, for more than four decades. We present an overview of the present state ATLAS superconducting technology, the latest approaches for superconducting cavity cryomodules commissioned within the last 10 years and the outlook and potential impact of transformative new technologies to low-beta ion accelerators.
 
slides icon Slides THZD2 [14.708 MB]  
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