An integrated 3D field circuit coupled model for comparative study of quench behavior in NI REBCO coil under 3D and 2D axisymmetric framework

Abstract

Abstract

Abstract Non-insulated (NI) high-temperature superconducting (HTS) coils are widely used in various applications such as high-field and fusion magnets, rendering the precise evaluation of their thermal stability essential. Recently, 2D axisymmetric models are adopted by some researchers to simulate the minimum quench energy (MQE) and normal zone propagation velocity (NZPV) of circular NI coils in the event of whole-turn quench. However, the 2D axisymmetric model neglects the disparities of physical field variables in the circumferential direction, potentially resulting in inaccurate predictions. Therefore, this work develops a 3D quench model incorporating the screening currents of NI coils by coupling the 3D T-A formulation with the PEEC (Partial Element Equivalent Circuit) network. The entire quench model is integrated into a single COMSOL program, which avoids complex cross-platform interaction. Meanwhile, a 2D axisymmetric model is constructed based on existing voltage-driven T-A formulation. The above two models share identical parameters to facilitate a quantitative comparison of their simulation results for quench dynamics. To validate their effectiveness, the charging results of the two models are compared, showing good agreement. Moreover, due to the screening current effect, both models exhibit a transient increase in magnetic field during the initial stage of heating. However, even in the case of whole-turn quench, significant discrepancies remain in the quench propagation modes between the two models: the 2D axisymmetric model relies solely on thermal conduction and magnetic induction, failing to accurately characterize the current transfer mechanism observed in the 3D model. Further analysis indicates that the 2D axisymmetric model may overestimate the MQE under conditions of low coil contact resistivity. Nevertheless, the 2D axisymmetric model can be employed to rapidly estimate the approximate range of MQE in the 3D model. This paper provides valuable insights into the rational selection of different quench analysis models for NI coils.