Modeling D retention in W under D ions and neutrons irradiation

The behaviors of deuterium (D) retention in tungsten (W) under D and neutron irradiation are investigated using an improved cluster dynamics model. The effects of different factors are considered in detail, including ion energy, fluence and irradiation temperature. The calculated results for different cases are comparable with experiments much well. It shows that the competition of trapping and diffusion effects dominates the behaviors of D in W. Different mechanisms give rise to the corresponding features in four typical zones of the depth distribution of D in W, i.e., the trapping of D by ion-induced vacancies to a peak in the near surface (0–0.2 μm), the recombination of ion-induced self-interstitial atoms with vacancies/deuterium-vacancy clusters to a decrease in the sub-surface (0.2–3 μm), D diffusion and accumulated by inherent vacancies to a platform in the range of 3 μm to tens of microns and the limit of diffusion to a reduction along depth in the bulk. The synergistic effect of neutron irradiation changes the depth distribution itself but the amount of D retained in W.