Fluctuation-induced particle transport during sawtooth reconnections in H-mode plasmas on HL-2A tokamak

The inward particle flux has been observed in many fusion devices[1, 2] and has attracted attention through its involvement in suppressing turbulence and forming the transport barrier in fusion research[3]. The fluctuation-induced inward particle flux after the sawtooth reconnection has been measured in H-mode plasmas by using the probes. Sawtooth reconnections generally exist near the q = 1 magnetic surface of the tokamak, and sawtooth reconnection periodically causes outward particles and heat transport from the core. During recovery of plasmas, an inward flux peak can be observed after a sawtooth reconnection, meanwhile, the edge transport barrier begins to form. Low-frequency fluctuations (<50 kHz) contribute to most of the inward flux. The magnetic turbulence increases two orders of magnitude after crash, where Maxwell stress induced particle flux can play an important role in inward particle flux.