Effects of external kink and fishbone-like modes on energetic particle transport in tokamak plasmas

Abstract Transport and loss of beam injected energetic particles (EPs) due to three-dimensional perturbations, associated with the external kink (XK) instability fishbone-like mode (FLM), are numerically investigated utilizing guiding center following code ORBIT for static toroidal plasmas in HL-2A. The perturbation structure XK is computed by MARS-F then mapped Boozer coordinates as defined ORBIT. simulation shows that EP profile experiences a significant change middle plasma column, when XK-induced radial magnetic field amplitude, normalized equilibrium field, exceeds threshold value about 10 − 2 . transport found be dominated diffusion process instead convection. Furthermore, scanning frequency free parameter while maintaining (thus mimicking FLM observed DIII-D JT-60U tokamaks), redistribution EPs substantially enhanced strong resonances between EPs, ∼2 kHz case considered. For either or FLM, response passing dominant assumed tangential neutral injection. Most lost these instabilities initially but eventually through trapped orbits.