Enhanced Quench Protection in REBa2Cu 3Oδ-7-Based Coils by Enhancing Three-Dimensional Quench Propagation via Thermally Conducting Electrical Insulation

Abstract

This simulation explores the effects of insulation properties on quench propagation in ReBa 2Cu 3O δ-7-based coils. At present, superconducting magnets primarily use insulators that are electrically and thermally insulating, for example, Kapton. Here, the impact of varying the thermal conductivity of the electrical insulation on quench behavior is reported. In particular, the behavior of a Kapton-insulated coil is compared with one insulated with doped TiO 2, one insulated with “ideal Al 2O 3”, and one noninsulated coil. The effects on minimum quench energy and normal zone propagation behavior are investigated. In addition, a new concept, the current sharing volume (CSV), which accounts for two- or three-dimensional normal zone propagation, is introduced. The CSV is defined as the volume of coil for which the temperature is above the current sharing temperature. The simulation results show that the transverse thermal conductivity and insulation thickness strongly influence the normal zone propagation velocity, thus impacting the quench detection time and hotspot temperature. As expected, the coils insulated with the higher thermal conductivity alternatives exhibited faster normal zone growth and lower hotspot temperatures relative to CSV growth. The impact of improved thermal conductivity of turn-to-turn insulation becomes even greater when distributed sensing replaces voltage-based sensing.