Superconducting rf structures - test facilities and results

The design of the TESLA superconducting electron-positron linear collider with an integrated X-ray laser laboratory was presented to several international committees including the German Science Council, advising the German government in matters of science. In preparation of this large facility, the TESLA Test Facility was set up at DESY. More than 40 institutes from nine countries have designed, constructed, commissioned and operated accelerator components. In close collaboration, superconducting accelerator cavities with gradients between 25 and more than 40 MV/m were developed. The TESLA Test Facility includes the preparation and testing of superconducting cavities as well as a 260 m long linac installation. The cavity performance with beam has been investigated while operating the linac as a driver for a SASE free-electron laser as well as during dedicated high gradient tests. More than 16 thousand hours of operation demonstrated this technology. Results of single cavity tests as well as of module tests without and with beam are presented.