Simulation of local dissipation phenomena in the REBCO insert of the 25-T CSM magnet: Understanding and preventing destructive thermal runaway

We recently developed an electrothermal model to study the occurrence and evolution of dissipative zones in a Rare-Earth BaCuO (REBCO) high-temperature superconductor (HTS) coils, considering the local critical current (I_c) inhomogeneity with a centimeter-scale resolution. In this study, we present an application of this model, implemented in Comsol Multiphysics, to the REBCO insert of the 25-T CSM magnet developed in the High Field Laboratory for Superconducting Material of Tohoku University. The destructive thermal runaway event or 'quench' observed on that coil will be introduced, followed by the modeling approach that was used to model it. We could simulate the coil behavior with a single 2-cm-long defect and verify that a more sensitive detection system in the millivolt range could be used to safely protect such magnets even from such a local defect. In the case of a more usual inhomogeneity distribution of I_c, the temperature rise is more homogenous and safe protection can be reached even at higher detection levels.