Simulation study of sputtering erosion and impurity deposition on carbon and tungsten surfaces irradiated with deuterium plasmas including carbon impurity

Sputtering erosion and impurity deposition on C and W surfaces irradiated with D+ plasmas containing C4+ impurity have been studied. For the C target, the net erosion is suppressed by the local redeposition resulting from charge exchange reactions of chemically sputtered CDx with D+ at the high plasma density and low plasma temperature. The D/XB values for CD4 reaction chains with electrons plus deuterium ions are lower than those for CD4 reaction chains with electrons at the low temperature. At the high temperature, these D/XB values which reproduce the experimental data are almost the same. For the W target, in association with the C4+ impurity concentration, the erosion and deposition occur near to and far from the LCFS, respectively, which qualitatively reproduces the experimental data. The erosion and deposition fluctuate depending on the target temperature. The fluctuation is explained by an interrelation between the diffusion and the reflective scattering collision.