The vacuum system for the superconducting linac of the TESLA Test Facility

Among the different approaches towards a next generation 500 GeV e + e − linear collider, the TESLA design uses superconducting accelerating structures operating at 1.3 GHz with a gradient of 25 MV/m. Presently, the TESLA test facility, which includes a prototype linear accelerator with superconducting cavities, is build up at DESY/Hamburg to serve as an R&D; tool. First, electrons have been accelerated in spring 1997. In the present state of the project two cryomodules, each containing eight solid niobium cavities are installed. One of the major objectives for the beam vacuum system is to preserve the cleanliness of the superconducting cavity surfaces and thus the operation at high gradients and high Q. Contamination by any sort of dust or condensation of gases during assembly and operation has to be absolutely avoided. Thus all vacuum components are carefully cleaned in clean rooms to make them particle free. Local clean rooms are used for installation of the components into the linac. A description of the linac vacuum system, the running experience and the present status of the project is given