Dynamic simulation of erosion and redeposition on plasma facing materials

Oya, Kaoru*; Tanabe, Tetsuo*; Takenaga, Hidenobu; Inai, Kensuke*

Dynamic simulation results of erosion and redeposition on plasma facing materials were reported. In JT-60U W-shaped divertor, erosion was dominant on the outer divertor plate, whereas deposition was dominant on the inner plate. The erosion and redeposition patterns on the plates were calculated using the EDDY code, which treats transport of impurities released from the plates in the plasma and dynamic material mixing processes. Forthermore, energy-dependent reflection and dissociation of hydrocarbons on the surface was employed in addition to a constant sticking coefficient on the plate. Hydrocarbons released from the outer divertor plate were immediately ionized when entering the plasma and were redeposited near the release position. But they were subjected to re-erosion, resulting in small effective sticking. On the whole, most area of the outer divetor plate was eroded. In contrast, the inner divertor plate was dominated by deposition due to lower plasma temperature. These results agreed with the experimental observations. Simulations for the twin test limiter experiments in TEXTOR, hydrocarbon redeposition in castellated surfaces and molecular dynamics of ion-solid interactions were also reported.