The distribution and nature of 3He implantation-induced defects in polycrystalline W samples were studied, by means of positron annihilation spectroscopy, as a function of implantation fluence. The implanted He profile was determined by nuclear reaction analysis, and its evolution under various annealing treatments was investigated. The results showed that vacancy-like defects were generated along the path of the ions, and that their concentration varied directly as the implantation fluence. No He desorption was observed for any of the thermal treatments. A change in the 3He depth profile under specific annealing conditions suggested the formation of nm-sized He bubbles.

Helium Behaviour and Vacancy Defect Distribution in Helium Implanted Tungsten. A.Debelle, M.F.Barthe, T.Sauvage, R.Belamhawal, A.Chelgoum, P.Desgardin, H.Labrim: Journal of Nuclear Materials, 2007, 362[2-3], 181-8