Effect of carbon and tungsten plasma-facing materials on the divertor and pedestal plasma in EAST

Abstract

The edge plasma simulation code SOLPS-ITER is applied to study the effects of plasma-facing materials (PFMs) on the plasma in the EAST device, whose lower carbon (C) divertor will be replaced by tungsten (W) material. The significant difference in particle and energy reflection coefficients between the C and W materials may influence the production and dynamics of the neutral particles in the divertor region, which is characterized by the collisions between the plasma and the recycled neutrals. To separate other effects on the plasma, only the particle and energy recycling of different materials are considered, and no impurity is included. Three PFMs cases, (i) full C PFMs, (ii) W divertor and C main chamber wall (MCW), and (iii) C divertor and W MCW, are simulated. The simulation results show that the PFMs have a remarkable impact on the neutral particles’ recycling, and thus the divertor and pedestal plasma. The C divertor is more capable of enhancing the neutral density in the divertor, and promoting the achievement of the plasma detachment than the W divertor is. However, the PFMs of the MCW have little influence on the divertor plasma. The simulation demonstrates that the C divertor is better than the W divertor from the plasma detachment point of view. In addition, both the divertor and the MCW PFMs have significant roles in the pedestal plasma.