Simulation of coupled sputter-diffusion effects

The simultaneous effects of sputtering, implantation and solid-state diffusion determine the surface profiles of mixed-material systems under ion-bombardment at elevated temperatures due to the enhanced atomic mobility. To simulate the joint processes the Monte Carlo code SDTrimSP for the simulation of the ion–solid interaction has been augmented by a diffusion model for solid-state diffusion. The combined model has been applied to a tungsten–iron system under deuterium bombardment as model system for EUROFER. The simulation results reveal a strong dependence of the surface profile on initial tungsten concentration, ion energy, temperature and fluence but also on the impinging flux, a parameter which is often not appropriately taken into account. For reactor relevant parameters of low-energy (200 eV) deuterium fluxes of ${10}^{21}at{m}^{-2}{s}^{-1}$ at 873 K a tungsten–iron system exhibits an increase of the tungsten surface concentration from initially 1% by a factor of more than 20, which drops at lower fluxes. (topical articles)