Deuterium retention in self-damaged tungsten

Surface and sub-surface morphology and deuterium retention in polycrystalline tungsten, undamaged and pre-damaged with 5.5 MeV W2+ ions to damage levels of 0.04, 0.4, and 1.2 dpa, with and without subsequent annealing at 1200 K for 2 h, have been examined after irradiation with low-energy deuterium ions up to a fluence of 1 x 10(26) D/m(2) at various temperatures. The morphology changes were investigated by scanning electron microscopy in combination with focused ion beam surface cutting. The different hydrogen binding states were investigated by thermal desorption spectroscopy, and the depth profile of the implanted D was measured by ion beam nuclear reaction analysis. The dependence of the D retention on the damage level and the implanted fluence was studied, and the results show saturation for 0.4 dpa independent of the deuterium implantation fluence. Additionally, it was observed that self-implantation introduces high temperature traps which can almost completely be removed by annealing at 1200 K. (C) 2009 Elsevier B.V. All rights reserved.