Hydrogen isotopic effects on the chemical erosion of graphite induced by ion irradiation

This theoretical study investigates the dynamic behavior of chemical erosion of graphite due to hydrogen-isotope ion bombardment. The ion energy ranges from 10 to 1000 eV and the target temperature ranges from 300 to 1100 K. The chemical erosion processes under investigation included surface-related and thermally activated hydrocarbon emission processes. The computer code TRIDYN was employed. The proposed simulation model was fitted to experimental data by implementing surface-related and thermally activated coefficients. It is improved compared to our previous model by incorporating a depth-dependent probability for out-diffusion of hydrocarbons. The local reduction of carbon density due to either physical sputtering or chemical erosion was also taken into account. Furthermore, the erosion for all three hydrogen isotopes – hydrogen, deuterium, and tritium – was modeled. All the calculated and fitted results are in good agreement with measured data. The results from the current simulation model surpass previous ones in the low ion energy region in which chemical erosion is of vital importance.