Simulation study of carbon impurity dynamics on reduced-activation ferritic/martensitic steel material at elevated temperatures under hydrogen exposure

The temperature dependence of net erosion of a Reduced-Activation Ferritic/martensitic steel (RAF) target, F82H, exposed to 0.33 keV H+ (H: 99.2%) and 1 keV C+ (C: 0.8%) has been studied in terms of the diffusion of C impurity deposited on the target and its chemical erosion (CH4 release) by H+ impact. Calculated results are in good agreement with the experiments, which indicates that the diffusion and chemical erosion play a key role in the temperature dependence. At low temperatures below 500 K, both effects contribute little. At median temperatures of 500–773 K, there is a significant contribution of chemical erosion, while a significant contribution of the diffusion occurs above 1000 K. Also, the dependence of the net erosion on the C impurity concentration for a variety of the temperatures has been studied. At the low temperatures, the net erosion is suppressed with increasing C impurity concentration (<C: 2.0%), while it is enhanced at the median temperatures. At the high temperatures, there is a suppression of the net erosion.