Modeling tungsten and carbon sputtering by carbon at elevated temperatures

The planned use of carbon strike plates adjacent to tungsten tiles in the ITER divertor will lead to W erosion by sputtered C ions. The W sputtering yield by C decreases with increasing surface concentration of the implanted C. However with increasing temperature, the C self-sputtering yield increases, reducing the rate of C surface coverage. This study attempts to model the temperature dependent C self-sputtering process and its impact on W erosion by using modified surface binding energies (SBEs) in TRIDYN. The SBEs are benchmarked against C self-sputtering yields measured in this study and W irradiation by C is simulated and compared to previous experimental results. Good agreement between simulation and experiments is seen at 670 K, while small deviations are observed at 770 K due to surface roughening. At 870 K, significant deviation is observed which can be attributed to enhanced surface roughening as well as diffusion effects.