A Study on Cooling Performances and Over-Current Behaviors of GdBCO Coils With Respect to Epoxy Impregnation Methods

The thermal and electrical stabilities of two epoxy-impregnated GdBCO coils, one wet-wound with epoxy resin every turn and the other impregnated with epoxy resin using vacuum pressure impregnation (VPI) after dry-winding, were evaluated through cool-down, over-current, and repetitive cooling tests. During the cool-down test, the VPI coil showed a more rapid cooling rate compared to the wet-wound coil. The VPI coil also exhibited better thermal and electrical stabilities in the over-current tests because the quench heat could easily be dissipated due to the absence of epoxy between turns. Moreover, in the repetitive cooling tests, the VPI coil exhibited reduced degradation in the superconducting property compared to the wet-wound coil due to lower vulnerability to the discrepancy of thermal contraction between the GdBCO tape and the epoxy resin.