Experimental study on the sorption performance of New–Fashioned silver getters compared with the traditional PdO in High–Vacuum multi–layer insulation vessels

Abstract

Hydrogen (H2) getter is one of the indispensable tools in high–vacuum multi–layer insulation (HVMLI) vessels. This study investigated several new–fashioned and low–cost H2 (i.e. silver getters) getters to replace expensive palladium oxide (PdO). The silver getters (SPSG, BPSG and Ag400B2) combined the advantages of chemical and physical sorption, which is referred to as physicochemical sorption in this study. An experimental platform was set up to test the properties of the silver getters. The sorption capacity of the silver getters was calculated using the constant volume method. The results reveal that BPSG, SPSG29g, SPSG51g and Ag400B2 have sorption capacities of 6.23%, 0.094%, 0.097% and 14.54% of that of PdO, respectively. However, the manufactured cost of physical chemisorption getters is just 0.4%–3% of that of PdO. Furthermore, when PdO sorbs H2, a substantial amount of sorption heat is generated, posing a potential threat to HVMLI vessels. Therefore, it is recommended to use 7 times Ag400B2 and 16 times BPSG instead of palladium oxide as the cryogenic getters under equivalent conditions. These findings provide a basis for applying silver getters in the HVMLI vessels, which greatly reduce the cost of cryogenic getters.