The presence of runaway electrons during the disruption evolves into a runaway current, which carries a large amount of energy and will cause irreversible damage to the tokamak device in case of an impact on the device wall, and thus requires attention. It is found that the plasma parameters before plasma disruption, such as the boundary safety factor, the magnitude of the toroidal magnetic field, and the electron density, affect the formation of the runaway current during the experiment, which can also be interpreted as affecting the confinement of the runaway electron seeds during thermal quench, but there is no relevant numerical simulation study yet. In this paper, the experimental results are reproduced qualitatively using the NIMROD simulation code, and the runaway electron confinement during thermal quench is investigated using a test particle model. Different parameters are found to affect the runaway electron confinement in their respective ways.
 

tokamak, disruption, runaway electron, J-TEXT, simulation