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