Simulation on the suppression effect of external passive field on runaway electrons on J-TEXT

Disruption-induced runaway electrons greatly reduce the lifespan of the nuclear fusion magnetic confinement device tokamak. At present, passive runaway electron mitigation coils have been modeled on the tokamak device SPARC and preliminary simulation results have been obtained. In this work, we use the three-dimensional nonlinear magnet-o-hydrodynamics (MHD) program NIMROD to study the impact of different mode and phase of the passive field on J-TEXT tokamak in the presence of a massive injection of argon impurity gas. The results indicate that the behavior of runaway electrons is significantly influenced by the passive runaway electron mitigation coils. It also reveals that under the same helicity condition of coil configuration, better results can be captured by operating in low-n mode. Under specific phases of operation, the coils in the 1/1 mode can completely suppress runaway currents.