Author: Fuwa, Y.
Paper Title Page
MOP064 Performance of First Prototype Multi-Cell Low-Surface-Field Shape Cavity 222
  • R.L. Geng
    JLab, Newport News, Virginia, USA
  • Y. Fuwa, Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Hayano
    KEK, Ibaraki, Japan
  • H. Ito
    Sokendai, Ibaraki, Japan
  • Z. Li
    SLAC, Menlo Park, California, USA
  The idea of cavity shaping for higher ultimate acceleration gradients has been proposed for some time, Low Loss/Ichiro and Re-entrant being examples, both seeking a lower Hpk/Eacc at the expense of a higher Epk/Eacc. While experimental verification in single-cell cavities of those shapes was very successful including the record gradient of 59 MV/m, pushing multi-cell cavities of those shapes to higher gradients was prevented by field emission. The Low-Surface-Field (LSF) shape seeks not only a lower Hpk/Eacc but also a lower Epk/Eacc, therefore it has the advantage of raising ultimate gradient at reduced field emission. The first multi-cell LSF shape prototype cavity was built using the standard forming and welding techniques. RF tests have been carried out, following standard ILC TDR baseline surface processing and treatment recipe. Three out of five cells achieved Hpk values corresponding to Eacc 50 MV/m. The current limit is the field emission in end cells. Instrumented testing following end-cell wiping and HPR with larger nozzles is in progress. We will present detailed experimental results and preparation procedures.  
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About • paper received ※ 24 June 2019       paper accepted ※ 30 June 2019       issue date ※ 14 August 2019  
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