Impact of ECRH on runaway electron generation during plasma disruptions in the HL-3 tokamak

This work investigates the impact of Electron Cyclotron Resonance Heating (ECRH) on runaway electron (RE) generation during MGI-triggered disruptions on the HL-3 tokamak. During these disruptions, a large RE current is formed, primarily through the hot tail generation and the avalanche process of REs. A comparative study found that applying 1 MW of ECRH during the disruption enhanced and sustained the RE beam, creating a higher-current and longer-lasting plateau compared to the non-ECRH case. Diagnostic analysis suggests that the presence of ECRH correlates with reduced initial particle losses during the thermal quench and may result in a more sustainable RE seed population. Furthermore, HXR spectra reveal ECRH actively heated the bulk RE population, raising its temperature from 0.13 MeV to 0.36 MeV. These findings demonstrate that active ECRH during a disruption can be harmful for tokamak operation, suggesting auxiliary heating systems must be integrated into disruption mitigation systems for immediate plasma termination.