TESLA RF POWER COUPLERS DEVELOPMENT AT DESY.

Abstract

Different RF power couplers for the TESLA Test Facility (TTF) [1] are under development and operation at DESY. TTF power couplers type II which are mainly used up till now together with FNAL couplers [2] recently have been improved by design of coupler TTF III [3]. RF power couplers are tested normally with full RF power, at first two couplers on a test stand and afterwards each coupler together with its superconducting cavity in a horizontal test cryostat. Results of coupler tests showed stable operation at full pulse length of 1.3 ms and RF power even up to about 1 MW without breakdowns. The average power needed for cavity operation at about 25 MV/m is 230 kW. New procedures to improve RF performance and to shorten processing time, like TiN coating of the inner surfaces, are being investigated. Also, the next coupler designs TTF IV and V are being developed.