Surface roughness effect on Mo physical sputtering and re-deposition in the linear plasma device PSI-2 predicted by ERO2.0

Surface morphology and its evolution during the plasma irradiation is known to have a large influence on the erosion and resulting lifetime of plasma-facing components as well as tritium retention. For instance, surface roughness can affect physical sputtering, re-deposition, as well as angular distributions of the sputtered species. In this study the effect of surface roughness is implemented into the 3D Monte-Carlo code ERO2.0. First modelling results for molybdenum (Mo) irradiated with deuterium (D) in the conditions foreseen for the planned experiments at the linear plasma device PSI-2 are presented. Using the constructed examples of surfaces with various (regular and fractal) roughness types it is shown that the effective sputtering yield decreases for rough surfaces in comparison to smooth ones. The angular distribution of particles escaping from the rough surface collimates with the increase of the surface structure's aspect ratio. Moreover, the modelling predicts flattening of the surface during the plasma irradiation due to the preferable re-deposition in the "valleys" and sputtering of the peak tops.