Numerical investigate of tokamak runaway current suppression by massive deuterium-argon/neon mixture gas injection

Tokamak plasma disruption can generate runaway current, and if not suppressed, the enormous energy they carry will cause severe damage to the equipment. This study employs the fluid model in the DREAM program to investigate the impact of deuterium-argon/neon mixture gas injecting on the runaway current during disruption. The research indicates that deuterium-argon/neon mixture gas injecting can suppress the eventual formation of platform runaway current. Within the range of the pre-disruption plasma current, Ip, the optimal concentration of argon/neon in the mixture gas should be between 0.50% and 0.70%, and the deuterium injection level should be between 1020 m-3 and 1021 m-3. Outside of this range, the suppression effect of deuterium-argon/neon mixture gas injection on the runaway current weakens, and even increases the runaway current. The pre-disruption plasma current, Ip, is a key factor affecting the runaway current. The larger the Ip, the larger the runaway current formed, and the more mixture gas needs to be injected. In tokamak devices with fusion reactor-level plasma currents up to 10 MA, the density of injected mixture gas needs to reach 1022 m-3, which cannot be achieved by current Massive Gas Injection (MGI) technology. Injecting deuterium-argon/neon mixture via shattered pellet injection will be a more feasible approach.