The Performance of the 1.3 GHz Superconducting RF Cavities in the First Module of the TESLA Test Facility Linac

The design goal of the 1.3 GHz 9-cell superconducting RF cavities for the Tesla Test Facility (TTF) is a gradient Eacc ≥ 15 MV/m at a quality factor of Qo ≥ 3·109. The cavities are operated in pulsed mode: 0.8 ms constant gradient with 10 Hz repetition rate. After the vertical acceptance test and prior to the assembly in the linac the cavities are tested in a horizontal cryostat fully equipped with helium vessel, high power input coupler, higher order modes coupler and tuning system. After installing module 1 the first 120 MeV beam has been delivered successfully. We report about the measured results in vertical and horizontal tests, the processing of the superconducting cavity system in the first module and the performance of the cavity system before, during and after operating the linac.