Hydrogen and helium trapping in tungsten under simultaneous irradiations

Hydrogen and helium trapping in polycrystalline tungsten under simultaneous He+–H+ and He+–D+ irradiation was measured by thermal desorption spectroscopy. At 300 K: He retention and release are affected very little by the presence of H, closely following He+-only irradiations; He is trapped within ∼30 nm of the surface. D retention is similar to D+-only levels but the presence of He enhances D trapping in the near surface, while limiting D diffusion into the bulk; D is trapped within ∼30–35 nm of the surface possibly at interstitial sites surrounding He–vacancy defects. At 700 K: He retention and release are again similar to He+-only cases; He is trapped within ∼30 nm of the surface while no D is observed.