Kinetic modelling of material erosion and impurity transport in edge localized modes in EAST

The kinetic modelling of material erosion and impurity transport on divertor plates in edge localized modes (ELMs) in tokamaks has been performed using the SDPIC and ITCD codes. The kinetic information on impinging particles and background plasma such as incident angle and energy, electric potential and field during ELMs can be well treated by the SDPIC code; this is generally difficult to obtain in experiments and fluid simulations due to diagnostic and technical limitations. The heat flux modelled with the SDPIC code can well reproduce the experimental result in EAST. The major power delivered by ions results in a strong increase of the erosion rate for both carbon and tungsten substrates during ELMs. The variation of the incident angle of impinging particles can be interpreted by the change of the potential drop induced by fast electrons during ELMs. The time difference in the peak values of erosion rate between the carbon and tungsten substrates is determined by the particle flux and sputtering yield. The heat loads for present ELMs in EAST cannot cause the ablation and melting of surface material. The eroded tungsten species show different transport properties from the eroded carbon species due to the small mean free path of W atoms and consequent prompt redeposition. A W self-sputtering avalanche is not observed during ELMs, ascribed to the small kinetic energy carried by the redeposited W species