Sputter yield reduction and fluence stability of numerically optimized nanocolumnar tungsten surfaces

Abstract

Nanocolumnar tungsten surfaces were investigated with numerical techniques regarding their potential to reduce sputtering by ion bombardment. We simulated a large number of different configurations with the SPRAY sputtering code to identify an optimal geometry. For the test case of 2 keV Ar+ irradiation, a specific configuration was found which led to a significant sputter yield reduction for all studied ion incidence angles. For example, reductions by ∼80% in comparison to the sputter yield values for a flat tungsten surface were observed during irradiation along the surface normal. These properties appear beneficial for application on first wall materials in nuclear fusion devices. The optimized surface was further investigated with the molecular dynamics code PARCAS and the binary-collision-approximation code SDTrimSP-3D, which supported the choice of this configuration. Furthermore, dynamic erosion simulations using SDTrimSP-3D were conducted, which predict a relatively long-lasting persistence of the sputter yield reduction if the structure is exposed to higher fluences.