Author/Authors :
Ohya، نويسنده , , K and Tanabe، نويسنده , , T and Rubel، نويسنده , , M and Wada، نويسنده , , M and Ohgo، نويسنده , , T and Hirai، نويسنده , , T and Philipps، نويسنده , , V and Kirschner، نويسنده , , A and Pospieszczyk، نويسنده , , A and Huber، نويسنده , , A and Sergienko، نويسنده , , G and Brezinsek، نويسنده , , S and Noda، نويسنده , , N، نويسنده ,
Abstract :
The erosion and deposition patterns on tungsten and tantalum test limiters exposed to the TEXTOR deuterium plasma containing a small amount of C impurity are simulated with the modified EDDY code. At the very top of the W and Ta limiters, there occurs neither erosion nor deposition, but the erosion proceeds slowly along the surface. When approaching the edge, the surface is covered by a thick C layer, which shows a very sharp boundary similar to the observation in surface measurements. In the erosion zone, the re-deposited carbon forms a W (Ta)–C mixed layer with small C concentration. Assumptions for chemical erosion yields of ∼0.01 for W and <0.005 for Ta fit the calculated widths of the deposition zone to the experimentally determined values. Possible reasons for the difference between W and Ta are discussed.
