Author: Gonnella, D.
Paper Title Page
MOPCAV013 LCLS-II-HE Vertical Acceptance Testing Plans 291
 
  • J.T. Maniscalco, S. Aderhold, J.D. Fuerst, D. Gonnella
    SLAC, Menlo Park, California, USA
  • T.T. Arkan, M. Checchin, J.A. Kaluzny, S. Posen
    Fermilab, Batavia, Illinois, USA
  • J. Hogan, A.D. Palczewski, C.E. Reece, K.M. Wilson
    JLab, Newport News, Virginia, USA
 
  LCLS-II-HE has performance requirements similar to but generally more demanding than those of LCLS-II, with an operating gradient of 21 MV/m (up from 16 MV/m in LCLS-II) and tighter restrictions on field emission and multipacting. In this paper, we outline the requirements for the 1.3 GHz cavities and the plans for qualification of these cavities by vertical test. We discuss lessons learned from LCLS-II and highlight the changes implemented in the vertical test procedure for the new project.  
poster icon Poster MOPCAV013 [0.413 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-MOPCAV013  
About • Received ※ 21 June 2021 — Revised ※ 12 July 2021 — Accepted ※ 21 August 2021 — Issue date ※ 02 May 2022
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THPCAV009 Statistical Modeling of Peak Accelerating Gradients in LCLS-II and LCLS-II-HE 804
 
  • J.T. Maniscalco, S. Aderhold, J.D. Fuerst, D. Gonnella
    SLAC, Menlo Park, California, USA
  • T.T. Arkan, M. Checchin, J.A. Kaluzny, S. Posen
    Fermilab, Batavia, Illinois, USA
  • J. Hogan, A.D. Palczewski, C.E. Reece, K.M. Wilson
    JLab, Newport News, Virginia, USA
 
  In this report, we study the vertical test gradient performance and the gradient degradation between vertical test and cryomodule test for the 1.3 GHz LCLS-II cavities. We develop a model of peak gradient statistics, and use our understanding of the LCLS-II results and the changes implemented for LCLS-II-HE to estimate the expected gradient statistics for the new machine. Finally, we lay out a plan to ensure that the LCLS-II-HE cryomodule gradient specifications are met while minimizing cavity disqualification by introducing a variable acceptance threshold for the accelerating gradient.  
poster icon Poster THPCAV009 [1.306 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2021-THPCAV009  
About • Received ※ 21 June 2021 — Revised ※ 14 September 2021 — Accepted ※ 02 November 2021 — Issue date ※ 23 November 2021
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FROFDV02
A Novel Approach to Producing High Gradient and Q0 Cavities in Non-Ideal Furnaces  
 
  • A.D. Palczewski, P. Dhakal, C.E. Reece
    JLab, Newport News, Virginia, USA
  • D. Gonnella
    SLAC, Menlo Park, California, USA
 
  Funding: Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Since the discovery of nitrogen doping in 2014, infusion in 2017, "mid-T bakes in 2018; the reproducibility in both Q0 and gradient has been proven to be highly variable between facilities and even within the same furnace within a facility*. Multiple studies have pointed to possible contamination from pumps, non-Molybdenum frame outgassing within a hot zone, gas purity issues, and cross-contamination between furnace runs. The traditional approach to mitigating these effects is using niobium furnace caps, high-temperature furnace burnout runs, and expensive pump replacements. We will show multiple examples of a novel approach to increasing Q0 and Q0+Eacc, using a simple treatment after a furnace treatment or doping + light EP. We will also outline the possible workflows using this new technique in production.
*Pashupati Dhakal, https://doi.org/10.1016/j.physo.2020.100034, and enclosed citations.
 
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