Cryogenic Tests of Ceramic Feedthroughs for SIS100 BPM

Due to the cryogenic environment in which the Beam Position Monitors (BPMs) will be used at SIS100 synchrotron special attention has to be turned to the BPMs’ signal feed-throughs (FT) [1]. Present design considers titanium based, N-Type FTs isolated with Al2O3 ceramics and welded into CF-16 flange. In a temperature range between room temperature and 4.2 K the requirements for the FTs are threefold: i) high mechanical stability, ii) vacuum-tightness even after many cold-warm cycles, iii) good and stable electrical connectivity. These features were tested in 10 cold-warm cycles in the temperature range given above.