Modelling of particle-reflection-distributions of rough surfaces

The modelling of plasma-wall-interactions (PWI) depends on distributions describing the angle- and energy distribution of particles scattered at first wall. Most PWI codes (e.g. SOLPS, EIRENE) rely on extensive tables based on reflection simulations (e.g. SDTrimSP-1D) or analytical formulae. However, both approaches assume an atomistically flat (smooth) surface. Rough surfaces which are formed under particle impact typically display a very different particle distribution compared to smooth surfaces. However, roughening is almost unavoidable, e.g. due to preferential sputtering, crystal-orientation dependent sputtering, precipitates, or thermal cycling. In this paper we investigate the effects of roughening on the reflection distributions using W- and W-Fe-surfaces of different morphologies within the binary collision approximation by SDTrimSP-2D. • Reflection properties of surfaces stronger affected by roughness than sputter yields. • In some structures even backward-reflection may become dominant. • Effect is present in amorphous and crystalline samples. • Efficient tabulation of data for PWI-codes appears feasible.