Investigating the distinct inward flux events following sawtooth crashes in HL-2A NBI plasmas

This study investigates the inward flux events following sawtooth crashes in the edge of HL-2A neutral beam heated plasmas. We identified three distinct types of inward fluxes with varying magnitudes and durations, each associated with unique plasma parameter fluctuations. Magnetic fluctuations, particularly the disruption of magnetic surface structures caused by sawtooth crashes, may play a significant role in modulating plasma dynamics. Moreover, the cross-phase term and coherence between density and velocity fluctuations were found to be key factors in these flux events, with high coherence correlating with peak inward flux. These findings enhance the understanding of fluctuation-induced transport after sawtooth crashes and have implications for plasma confinement in fusion devices.