Performance of a Superconducting 65-Cell-Structure in X-Band

For superconducting accelerator application a 65-cell X-band structure of 0.51 m length, with increasing phase velocity ß¿ (.52¿ß¿¿.94) was developed and constructed. After careful chemical tuning electropolishing, and UHV-annealing, Q-values of 109, and an accelerating field of 3.9 MV/m have been reached with a bath temperature of 1.8 K. This field corresponds to a peak electric field of 44 MV/m and a peak magnetic field of 83 mT. A set-up of specially prepared resistors and X-ray detectors showed that the quenching breakdown ocurred in the cell with the highest fields, without electron loading. Together with an 80 keV gun and beam focusing elements the structure has been operated as a small superconducting accelerator in the 2 MeV region.