The Accumulation of He on a W Surface During keV-He Irradiation: Cluster Dynamics Modeling

The accumulation of He on a W surface during keV-He ion irradiation has been simulated using cluster dynamics modeling. This is based mainly on rate theory and improved by involving difierent types of objects, adopting up-to-date parameters and complex reaction processes, as well as considering the difiusion process along with depth. These new features make the simulated results compare very well with the experimental ones. The accumulation and difiusion processes are analyzed, and the depth and size dependence of the He concentrations contributed by difierent types of He clusters is also discussed. The exploration of the trapping and difiusion efiects of the He atoms is helpful in understanding the evolution of the damages in the near-surface of plasma-facing materials under He ion irradiation.