Simulation Study on Erosion and Redeposition at Tungsten Surface Exposed to Deuterium Plasma Including Carbon

概要

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The erosion and redeposition at a W surface exposed to a D plasma including C impurity were simulated using the dynamic plasma-surface interaction program, EDDY. The computer code can simulate plasma ion reflection, physical and chemical sputtering, local atomic composition changes of bombarded surface, and mear-surface reflected and sputtered particle transport in magnetized plasmas. The simulation result was compared with experimental data, a sharp C deposition on the edge of W side of a W-C twin test-limiter after the TEXTOR-94 plasma exposure. The sharp C deposition is due to both the larger ratio of carbon ion flux and the lower plasma ion temperature at the edge, and is dependent upon the incident fluence. The contribution of chemical sputtering producing CD_4 due to the D ion bombardment of the C deposition layer was calculated, and the result shows the excellent agreement. Furthermore, the simulation calculation shows that a W deposition observed on the C side is mainly due to the prompt redeposition of W atoms sputtered from the top surface of the W side.
社団法人プラズマ・核融合学会の論文
2001-09-25