Author: Freyberger, A.
Paper Title Page
WEPMP053 Operational Results of Simultaneous Four-Beam Delivery at Jefferson Lab 2454
 
  • R. Kazimi, A. Freyberger, J.M. Grames, J. Hansknecht, A.S. Hofler, T. E. Plawski, M. Poelker, M. F. Spata, Y.W. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A concept for simultaneous beam delivery to all four CEBAF experimental halls from a single injector and a single main accelerator for the 12 GeV era was proposed in 2012. The original 12 GeV beam delivery plan was for a maximum of three experimental halls at a time as in the 6 GeV era. Therefore, the new concept increases the po-tential beam time for the experiments up to 33%. This change, although a major improvement in operational capabilities, required only limited modifications to the existing machine. The modifications were mainly timing and pattern changes to the beams in the injector, adding a fourth laser to the photo-cathode gun, and the addition of new RF separators to the highest pass of CEBAF. These changes are now complete and, for the first time, the full system is operating, producing four simultaneous beams through the accelerator to four different destinations. In this paper, in addition to presenting the results of the full system commissioning, we will discuss important details about the new configuration plus some of our operational challenges.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP053  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB097 Understanding and Mitigation of Field Emission in CEBAF SRF Linacs 3039
 
  • R.L. Geng, A. Freyberger, R.A. Rimmer
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We will present current understanding of field emission in two 1.1 GeV CW SRF linacs at CEBAF and its mitigation for improved CEBAF energy reach and operation reliability. This contribution will provide a review of CEBAF gradient evolution since 2014, the impact of field emission, the effort in understanding the root cause of field emission in operational SRF cavities including the recently installed C100 cavities. We will evaluate the effect of initial mitigations implemented since 2016, aimed at reducing generation and transportation of new field emitting particulates. Effects of cavity thermal cycling aimed at abating activation of settled field emitting particulates will be evaluated as well. Remaining issues toward predictable control of field emission in operational SRF cavities will be discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB097  
About • paper received ※ 19 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)