MEASUREMENTS ON NIOBIUM SUPERCONDUCTINGS C-BAND CAVITIES FOR LINEAR ACCELERATORS APPLICATIONS

Superconductings cavities for linear accelerators applications at 4.5 GHz (C-Band) have been constructed and tested. The Niobium cavities were obtained by electron beam welding of half cavities previously formed pressing Niobium sheets in a hydraulic press. In such cavities, operating in TM^0 mode, ac celerating field of 26.5 MV/m and pealc surface field of 50 MV/m were obtained at a power level of 30 W/m. The best quality factor obtained at this field level is Q =-2x.10^ at a temperature of 1.8°K. The set of tests on C-Band cavities shows: (1) our C-Band niobium cavities exhibit quite good R.F. properties analogous to the ones-measured at higher frequencies1(X-Band); (2) limitations on accelerating fields are re lated only to R.F. induced magnetic field. The electron loading due to field emission does not limit the maximum achievable field. © 1979 IEEE