Influence of Interturn Contact Stress on the Quench Behavior of Insulated YBCO Pancake Magnets: A Study Based on Numerical Simulations

Insulated high-temperature superconducting (HTS) magnets are still widely used in low-field applications, such as HTS motors and generators. In this article, a 2-D/3-D mixed electrothermal model and a homogeneous 3-D electrothermal model are employed to study the influence of interturn contact stress on the minimum quench energy (MQE) and longitudinal and transverse normal zone propagation velocities (NZPVs) of insulated YBCO magnets for the temperature range of 30–60 K. This temperature range is usually of interest in applications such as HTS motors, generators, and transformers because it allows the use of low-cost cooling systems. It is found that MQE increases significantly with increasing interturn contact stress. The interturn contact stress has small influence on the longitudinal NZPV of an insulated YBCO pancake magnet. However, the transverse NZPV rises significantly with the increase in interturn contact stress. The transverse NZPV is nearly proportional to the interturn contact stress. The 3-D homogeneous model gives results that are in agreement with those of the 2-D/3-D mixed model, especially for the temperature range of 45–60 K; however, the MQE and transverse NZPV given by the two models are different for the temperature range of 30–45 K. That means for insulated HTS YBCO pancake magnets operating in the temperature range 45–60 K, the 3-D homogeneous electrothermal model can be a good replacement for the 2-D/3-D mixed model to study the quench behavior, which can achieve better computational efficiency without significant loss of accuracy.