Characterization of Runaway-Triggered Spikes Discharge in the East Tokamak

In this paper, we investigate a regime of runaway discharges that is characterized by a strong enhancement of the relaxation oscillations seen in the electron cyclotron emission, Hα, visible bremsstrahlung and CIII emission, coupled with large spikes in the central line integral density, loop voltage, bolometer and Mirnov oscillations. In this regime, the background plasma is weakly ionized and low-temperature. The low-temperature background plasma can suddenly become heated by runaway electron beam–plasma instability. In this regime of runaway discharge, the primary mechanism of runaway electron generation is strongly suppressed because of the low temperature and low ionization of background plasmas.