Developments and achievements at the TESLA test facility (TTF)

The TESLA Test Facility (TTF), under construction and commissioning at DESY International Collaboration, is an R&D test bench for the superconducting option for future linear electron-position colliders. TTF consists of an infrastructure to process and test the SC cavities and of a 400 MeV linac (Phase I), to be upgraded up to 1.2 GeV (Phase II). The infrastructure is fully operational and the first cryomodule of the three planned for Phase I has been successfully in operation since June 1997. Each cryomodule contains eighty nine cell. Cavities at 1.3 GHz. The planned performances (15 MV/m with a Q of 3 10/sup 9/) have been outreached. The achievements on cavity development and cryomodule design allow expected cavity operation at 20 MV/m (at least) in the second cryomodule, that is planned to be in operation by November 1998. The TESLA goal of 25 MV/m is expected for the last six modules. An overview of the facility and of the results obtained so far in the critical technologies are presented in this paper, with a particular focus on the superconducting cavities.