An Inverse Calculation Study on Post-Quench Behavior of a No-Insulation REBCO Insert

This paper proposes an approach to account for a fast electromagnetic quench propagation among electromagnetically coupled no-insulation (NI) high temperature superconductor (HTS) coils. Recently, multiple groups have reported that the conventional lumped-circuit model, which has well demonstrated charging and discharging behaviors of an NI magnet, could not account for post-quench behaviors. Specifically, terminal voltages of individual pancake coils were estimated to be too high than the simulated ones. This paper proposes an approach that focuses on the post-quench simulation of an NI HTS magnet. To explain this phenomenon as a lumped circuit, a new approach was introduced. The key idea is inversely calculating key parameters of the lumped circuit that best demonstrates the non-linear post-quench behaviors. After defining the necessary assumptions, we adopted inverse-calculating methods to analyze the test results of high field NI HTS magnets. Simulation results suggest that after a quench, the index resistance changes in a different way from the previous theory, while the change in characteristic resistance is similar to conventional theory.