Speaker
Description
High temperature superconductor (HTS) coils are widely acknowledged for having greater stability margins than low temperature superconductor (LTS) counterparts. In particular, no-insulation (NI) coils are often assumed to exhibit even greater stability owing to enhanced thermal conduction between turns and inherent current bypass capabilities. However, we hypothesize that this assumption may not universally hold. Specifically, reducing the turn-to-turn contact resistivity in NI HTS coils can actually heighten their quench susceptibility, because normal zones can expand through an electromagnetic “inductive-type” mechanism rather than relying solely on the conventional “diffusive-type” thermal conduction. This fundamental difference in quench propagation necessitates distinct stability assessment methodologies for NI HTS coils.
In this study, we examine the influence of turn-to-turn contact resistivities on the stability of single pancake NI HTS coils by determining their minimum quench energy (MQE). Our findings reveal that MQEs for inductive-type quenches decrease as inter-turn contact resistivities are lowered, indicating an increased vulnerability of NI HTS coils to inductive-type quenches when inter-turn contact resistance is excessively reduced.
