Cryogenic and electrical test cryostat for instrumented superconductive RF cavities (CHECHIA)

This facility has been designed to carry out cryogenic RF quality factor (QRF) measurements, cold tuner tests, high order modes coupler tests, main coupler tests and full RF tests of superconducting cavities under real accelerator conditions (pulse mode, feedback loops, etc). The cryostat is built to receive one horizontally positioned cavity equipped with its helium vessel, its tuner and various RF couplers. The maximum heat load is ≈ 58 W (2.5 g/s) at 2 K for high power peak processing and ≈ 6 W (0.25 g/s) under normal conditions. QRF will be obtained from heat load measurements by LHe level variation and gas flow measurement at known temperature and pressure. The calibration is given by a DC electrical heater. The paper describes the design and the preliminary results of cryogenic performance tests of the cryostat itself.