Cryogenic rf test of the first plasma etched SRF cavity
  Plasma etching has a potential to be an alternative processing technology for superconducting radio frequency (SRF) cavities. An apparatus and a method are developed for plasma etching of the inner surfaces of SRF cavities. To test the effect of the plasma etching on the cavity rf performance, a 1497 MHz single cell SRF cavity is used. The single cell cavity is mechanically polished, buffer chemically etched afterwards and rf tested at cryogenic temperatures for a baseline test. This cavity is then plasma processed. The processing was accomplished by moving axially the inner electrode and the gas flow inlet in a step-wise manner to establish segmented plasma processing. The cavity is rf tested afterwards at cryogenic temperatures. The rf test and surface condition results are presented. 
J. Upadhyay, A. Palczewski, S. Popovi\'c, A.-M. Valente-Feliciano, D.   Im, L. Phillips, and L. Vu\v{s}kovi\'c
physics.acc-ph physics.atom-ph physics.plasm-ph