Comparison of different noble gas injections by MGI on plasma disruption mitigation on EAST

Abstract Massive gas injection (MGI) is a traditional plasma disruption mitigation method. This method directly injects massive gas into the pre-disruption plasma and has been developed on EAST. Different noble gas injection experiments, including He, Ne, and Ar, were performed to compare the mitigation effect of plasma disruption by evaluating the key parameters such as flight time, pre-thermal quench (pre-TQ), and current quench (CQ). The flight time was shorter for low atomic number (Z) gas, and the decrease in flight time by increasing the amount of gas was insignificant. However, both pre-TQ and CQ durations decreased considerably with the increase in gas injection amount. The effect of atomic mass on pre-TQ and CQ durations showed the opposite trend. The observed trend could help in controlling CQ duration in a reasonable area. Moreover, the analysis of radiation distribution with different impurity injections indicates that low Z impurity could reduce the asymmetry of radiation, which is valuable in mitigating plasma disruption. These results provide essential data support for plasma disruption mitigation on EAST and future fusion devices.