A study of the thermal characteristics of conduction-cooled superconducting magnets according to thermal expansion

Herein, we evaluated the thermal characteristics of high-temperature superconducting (HTS) magnets impregnated with thermally conductive adhesives. The thermally conductive adhesive and the HTS tape have different linear thermal expansion between room temperature (296 K) and cryogenic temperature (77 K), which results in peeling off the substrate of the HTS tape in the adhesive layer. Considering the thermal conductive passage of the adhesive impregnated HTS magnet is hindered by the gap in the adhesive layer, resulting in reduced thermal performance of the magnet. The coefficients of thermal expansion (CTE) of HTS tape and adhesive were measured and the gap on the adhesive layer after thermal cycling was confirmed through the scanning electron microscopy (SEM) images. Multi-physical analysis including mechanical and thermal analysis to quantitatively analyse the thermal conductivity (kappa) considering the CTE in the adhesive layer was performed and compared with experimental results. The result of this study would be useful in adjusting the CTE of adhesive impregnated conduction-cooled superconducting magnets.