Molecular dynamics studies of the sputtering of divertor materials

We use molecular dynamics (MD) simulations to study two important erosion processes of divertor materials, namely the chemical sputtering of carbon by hyperthermal deuterium and the self-sputtering of W by redeposited atoms. Although it is generally accepted that MD simulations can provide a good qualitative description of far-from-equilibrium processes, such as irradiation-induced cascades, we show that also good quantitative agreement with experiments is obtained. We further show that the chemical sputtering yield of carbon is reduced by Si doping at impact energies ≤20 eV. Significant carbon sputtering is still observed for both undoped and doped structures at 5 eV. Silicon sputtering is negligible at all impact energies studied. For W self-sputtering, sputtering yields higher than one are observed at ≥1 keV for normal incidence and at ≥500 eV for 20 deg. off-normal incidence