IMPROVEMENT OF CAVITY PERFORMANCE IN THE SACLAY/CORNELL/DESY’S SC CAVITIES

Development of 1.3 GHz Nb superconducting cavities for TESLA (TeV Energy Superconducting Linear Accelerator) has been carried out under an international collaboration. Three Saclay single-cell cavities, one Cornell two-cell cavity and one DESY nine-cell cavity were sent to KEK in order to compare the cavity performance. These cavities were tested at KEK after the following surface treatment: 1) high pressure rinsing, HPR, 2) chemical polishing and HPR, 3) electropolishing and HPR. Both the quench field and the cavity quality factor (Qo) at high fields were remarkably improved due to electropolishing in the single-cell cavities. No dependence of the quench field on the niobium RRR was observed in electropolished cavities.