A coupled EDDY/PIC/ELECTRAN simulation of erosion and deposition in gaps

To calculate complex plasma profiles in the gaps, the ELECTRAN code, which calculates secondary electron (SE) emission from metals, was combined with a two-dimensional kinetic code using the particle-in-cell (PIC) technique. We also performed a simulation of carbon/hydrocarbon deposition and re-erosion in the gaps on the condition that the plasma density and temperature were 1018 m−3 and 30 eV, respectively. A high flux of plasma ions occurred at the plasma-open side of the poloidal gap and at the E × B drift side of the toroidal gap. Although most of the carbon was redeposited at the side surface near the gap entrance, the redeposited carbon was re-eroded there due to plasma ion bombardment. As a result, erosion dominated at the plasma-open area near the gap entrance, whereas deposition dominated in deep regions.