Effects of thermal cycling and thermal stability on 2G HTS pancake coils

Abstract

Degradation of superconducting critical currents of 2G-HTS coils may appear upon thermal cycling due to the tensile stress differences of its elements that induce increasing tape damages. We report on the thermal cycling and thermal stability effects of round epoxy-impregnated pancake coils under two cooling conditions (liquid nitrogen and conduction cooling). Thermal stability has been analyzed by measuring the quench development and propagation. Minimum quench energy values and longitudinal and radial propagation velocities are reported. The influence of different epoxy impregnations and number of turns in the thermal cycling effects and quench behavior has been studied.