Cryogenic gas disconnect joints used in cryogenic accelerator cold-gas distribution systems

Demountable gas disconnect joints are the preferred choice for assembly of cryogenic (20 K) helium gas manifolding systems used with linear accelerators being developed at Los Alamos. The joints, which are used to distribute helium refrigerant gas at pressures as high as 450 psi, must also be capable of passing helium leak tests with a maximum leak rate of 5*10/sup -7/ std-cc/s at operating conditions. For this application, the authors have evaluated several forms of stainless-steel-to-stainless-steel and aluminum-to-stainless-steel flanged joints from several commercial manufacturers. They discuss using some of the joints in a linear accelerator. It was found that great care in assembly of the joints is necessary to assure that the joints will perform as expected. The identification of an acceptable aluminum-to-stainless-steel flange system, the Hakudo/ALFLAT, is very important for its application to the high-performance lightweight accelerators now being designed.<>