Enhanced plasma current spike formation due to onset of 1/1 kink-tearing reconnection during a massive gas injection process

Abstract

The formation of the plasma current spike at the end of the thermal quench (TQ) phase is studied systematically, which is found to strongly correlate with the onset of the 1/1 kink-tearing reconnection only in the simulation results presented here. The magnetohydrodynamic activity on the q = 1 surface plays a critical role in the spike formation and the disruption process. In particular, when the safety factor in the magnetic axis q0 exceeds 1, the plasma major disruption transits into successive minor disruptions, and the start of the TQ phase is delayed.