An Exponential Law of Hot Spot Temperature Versus Normal Zone Propagation Velocity During the Quench of an YBa2Cu3O7-δ Pancake Magnet

Abstract

Using a 2-D/3-D mixed electrothermal model, the quench behavior of an YBa2Cu3O7-δ (YBCO) pancake magnet is investigated for operating temperature 30–65 K. From many simulations, it is found when the hot spot temperature T peak rises to the range [120 K, 300 K], both T peak and the normal zone length L NZ behave like exponential functions of the longitudinal normal zone propagation velocity (NZPV), as the YBCO pancake magnet is quenched by a disturbance energy (DE) equal to or greater than the minimum quench energy (MQE). The exponential law of T peak versus NZPV, as well as L NZ versus NZPV, is not obviously affected by the heat disturbance parameters as DEs = MQEs. Similarly, the temperature rising rate d T peak/d t can be regarded as a function of T peak in [120 K, 300 K] and is not significantly affected by heat disturbance parameters as DEs = MQEs. These characteristics have potential usage in the formulation of quench detection/protection schemes of HTS YBCO pancake magnets.