Simulation study of the impacts of the parallel electron response and the Hall effect on the edge-localized mode for HL-3

Abstract In this paper, we investigate the impact of the parallel electron response and the Hall effect on edge-localized mode (ELM) crashes using the BOUT++ three-field model applied to a 1 MA H-mode discharge on HL-3. A scan of the edge safety factor q and magnetic shear s shows that the ratio HD of the Hall scaling factor to the dynamo scaling factor exceeds 0.3, indicating that the Hall effect at the pedestal cannot be neglected in HL-3. Simulations reveal that the drift-Alfvén wave (DAW) instability, driven by the parallel electron response, enhances the linear growth rate and hinders turbulence propagating to the inner part of the pedestal and the scrape-off layer, thereby reducing the ELM size. Impacts of E r shear on the DAW instability are studied by modulating the shear flow. Both co-directional (shear flow in the same direction as the ion diamagnetic drift) and counter-directional (shear flow in a different direction from the ion diamagnetic drift) flows do not alter DAW destabilization, but they weaken its suppression of turbulence transport and reduce the inward shift of the crash location. Compared to counter-flow, the DAW instability can lead to premature termination of the ELM crash and the suppressive effect of DAW instability on the ELM crash is significantly reduced when considering co-flow.