Methods for Improving the Transfer of Heat across the Copper and Gadolinium Gallium Garnet Interface

Abstract

Heat transfer across the interface between copper and gadolinium gallium garnet (GGG) is enhanced using various materials. These are helium gas, high vacuum grease, high purity indium, and Stycast 2850 FT epoxy. This qualitative study is conducted for temperatures between 2 K and 10 K. Helium gas improves the conductance of the interface but the improvement is limited by the low thermal conductivity of the gas. High vacuum grease improves the conductance less than does helium gas. High purity indium increases the conductance significantly and does not appear to degrade with temperature cycling. Stycast 2850 FT provides a similar improvement in the conductance; however, it can only be used for small area interfaces. A large Cu/GGG interface bonded with epoxy tends to fail when cooled to liquid helium temperatures.