Characterization of Bonnetless Cryogenic Valves

Abstract

This chapter conducts performance evaluation tests of 3 different kinds of BLCV to study the relationship between the respective valve structures and their performance and reliability, as well as the effectiveness of design methods.The Large Helical Device (LHD) is a nuclear fusion test system in which all coils are made superconductive and which requires the guarantee of constant cooling at liquid helium temperature to ensure superconductive action of the coils. Moreover, it is also necessary to accurately control the helium inside the cooling piping to uniformly cool the object material during cool-down operation. Control of liquid helium used for cooling the Large Helical Device (LHD) can be made more effective with Bonnetless Cryogenic Valves (BLCV) , which can be located in the proper places for use inside the helical coil by being constructed in such a way as to be placed inside vacuum insulated vessels, compared with the conventional long-bonnet cryogenic valves, which must be integrally installed in a valve box.