Fluence dependent changes of erosion yields and surface morphology of the iron-tungsten model system: SDTrimSP-2D simulation studies

•One- and two dimensional simulations resolve the long-standing mismatch between experiment and theory in the fluence scales needed for equilibrium sputtering yields in the Fe-W model system used as RAFM surrogate.•Initial tungsten inhomogeneities result in the formation of surface morphologies which cannot be considered in conventional 1D simulations and which considerably delay convergence to steady-state. The effect of different sample structures of an iron-tungsten model system (as a surrogate for reduced activation ferritic martensitic steels like EUROFER) on the development of surface morphologies, tungsten surface enrichment and sputter yields under low-energy monoenergetic perpendicular 200 eV deuterium bombardment has been studied with SDTrimSP-2d simulations. Previous modeling studies considering diffusive effects also could reasonably reproduce and explain the experimental results for a large set of experimental parameters like temperature, flux and sample concentration. However, for settings with negligible Fe-W-interdiffusion the fluence needed for steady-state conditions differed between the experiments and the simulations. Thus, the main focus of the present study is directed towards the elucidation of this fluence mismatch. Comparison of one and two-dimensional simulation results reveal a strong dependency of the tungsten enrichment on the sample homogeneity and a significantly delayed reduction of the erosion yield due to a pronounced formation of surface structures from initially flat sample surfaces.