  In this study, NIMROD simulations are performed to investigate the effects of
massive helium gas injection level on the induced disruption on EAST tokamak.
It is demonstrated in simulations that two different scenarios of plasma
cooling (complete cooling and partial cooling) take place for different amounts
of injected impurities. For the impurity injection above a critical level, a
single MHD activity is able to induce a complete core temperature collapse. For
impurity injection below the critical level, a series of multiple minor
disruptions occur before the complete thermal quench (TQ).
