Author: Ross, M.C.
Paper Title Page
MOFAA1 LCLS-II: Status, Issues and Plans 1
 
  • M.C. Ross
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by Department of Energy contract DE-AC02-76SF00515
The Linac Coherent Light Source II (LCLS-II) project requires the assembly, test, and installation of 37 cryomodules (CM) in order to deliver a 4 GeV CW electron beam to the FEL undulators for production of both hard and soft X-ray pulses at a repetition rate of up to 1 MHz. SRF cavity performance in the 30+ tested CM exceeds gradient and cryogenic dynamic heat-load requirements (set at 16 MV/m and 10 W resp). In this talk we present microphonics, shipping, magnetic-flux exclusion, and field emission performance. The US funding agency, DOE, has recently approved an additional 20 CM for the extension of LCLS-II to 8 GeV. This paper will also include initial cavity and heat-load performance results for the extension project, LCLS-II-HE. 		 
slides icon Slides MOFAA1 [30.146 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOFAA1  
About • paper received ※ 25 June 2019       paper accepted ※ 04 July 2019       issue date ※ 14 August 2019  
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MOP045 The LCLS-II HE High Q and Gradient R&D Program 154
 
  • D. Gonnella, S. Aderhold, A. Burrill, G.R. Hays, T.O. Raubenheimer, M.C. Ross
    SLAC, Menlo Park, California, USA
  • D. Bafia, M. Checchin, A. Grassellino, M. Martinello, A.S. Romanenko
    Fermilab, Batavia, Illinois, USA
  • M. Ge, M. Liepe, S. Posen
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • A.D. Palczewski, C.E. Reece
    JLab, Newport News, Virginia, USA
  
  Funding: US DOE and the LCLS-II HE Project
The LCLS-II HE project is a high energy upgrade to the superconducting LCLS-II linac. It consists of adding twenty additional 1.3 GHz cryomodules to the linac, with cavities operating at a gradient of 20.8 MV/m with a Q0 of 2.7·1010. Performance of LCLS-II cryomodules has suggested that operations at this high of a gradient will not be achievable with the existing cavity recipe employed. Therefore a research program was developed between SLAC, Fermilab, Thomas Jefferson National Accelerator Facility, and Cornell University in order to improve the cavity processing method of the SRF cavities and reach the HE goals. This program explores the doping regime beyond what was done for LCLS-II and also has looked to further developed nitrogen-infusion. Here we will summarize the results from this R\&D program, showing significant improvement on both single-cell and 9-cell cavities compared with the original LCLS-II cavity recipe. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP045  
About • paper received ※ 25 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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FRCAA3 Industrial Cavity Production: Lessons Learned to Push the Boundaries of Nitrogen-Doping 1199
 
  • D. Gonnella, S. Aderhold, A. Burrill, M.C. Ross
    SLAC, Menlo Park, California, USA
  • E. Daly, G.K. Davis, F. Marhauser, A.D. Palczewski, K.M. Wilson
    JLab, Newport News, Virginia, USA
  • A. Grassellino, C.J. Grimm, T.N. Khabiboulline, O.S. Melnychuk, S. Posen, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by US DOE Contract DE-AC02-76SF00515.
Nitrogen doping has been proven now in several labs to enhance Q0 values of 1.3 GHz cavities in the gradient domain favored by CW operation. The choice of doping for the LCLS-II project has given the community a wealth of statistics and experience on the challenge of transferring the doping technology to industry. Overall, industry-produced nitrogen-doped cavities have shown excellent performance, however some technical issues have arisen. This talk focuses on lessons learned from the production of over 300 nitrogen-doped cavities for LCLS-II and how issues were mitigated to further improve performance. Finally, I will discuss pushing the boundaries of nitrogen-doping further by exploring different doping regimes in order to maintain excellent Q0 performance, while reaching higher quench fields. 		 
slides icon Slides FRCAA3 [16.880 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAA3  
About • paper received ※ 02 July 2019       paper accepted ※ 03 July 2019       issue date ※ 14 August 2019  
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FRCAB7 Plasma Processing to Reduce Field Emission in LCLS-II 1.3 GHz SRF Cavities 1231
SUSP022   use link to see paper's listing under its alternate paper code  
TUP067   use link to see paper's listing under its alternate paper code  
 
  • B. Giaccone, J. Zasadzinski
    IIT, Chicago, Illinois, USA
  • P. Berrutti, B. Giaccone, A. Grassellino, M. Martinello
    Fermilab, Batavia, Illinois, USA
  • M. Doleans
    ORNL, Oak Ridge, Tennessee, USA
  • D. Gonnella, G. Lanza, M.C. Ross
    SLAC, Menlo Park, California, USA
  
  Plasma cleaning for LCLS-II 9-cell 1.3 GHz cavities is under study at Fermilab. Starting from ORNL method, we have developed a new technique for plasma ignition using HOMs. Plasma processing is being applied to contaminated and field emitting cavities, here are discussed the first results in terms of Q and radiation vs E measured before and after treatment. Further studies are ongoing to optimize plasma parameters and to acquire statistics on plasma cleaning effectiveness.  
slides icon Slides FRCAB7 [14.701 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAB7  
About • paper received ※ 23 June 2019       paper accepted ※ 04 July 2019       issue date ※ 14 August 2019  
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