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 similar to 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 similar to 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 similar to 30 nm of the surface while no D is observed. (c) 2007 Elsevier B.V. All rights reserved.