Optimization of epoxy-aluminium composites used in cryosorption pumps by thermal conductivity studies from 4.5 K to 300 K

Abstract

Cryosorption pump is a capture vacuum pump which retains gas molecules by chemical or physical interaction on their internal surfaces when cooled to cryogenic temperatures. Cryosorption pumps are the only solution in nuclear fusion systems to achieve high vacuum in the environment of hydrogen and helium. An important aspect of this development is the proper adhesion of the activated carbons on the metallic panels using a high thermal conductivity and high bonding strength adhesive. Typical adhesives used are epoxy based. The thermal conductivity of the adhesive can be improved by using fine aluminium powder as the filler in the base epoxy matrix. However, the thermal conductivity data of such epoxy-aluminium composites is not available in literature. Hence, we have measured the thermal conductivities of the above epoxy-aluminium composites (with varied volume fraction of aluminium in epoxy) in the temperature range from 4.5 K to 300 K using a G-M cryocooler based thermal conductivity experimental set-up. The experimental results are discussed in this paper which will be useful towards the development of cryosoprtion pumps with high pumping speeds.