Depth distribution of deuterium in single- and polycrystalline tungsten up to depths of several micrometers

Depth profiles of deuterium trapped in W single crystals and polycrystalline W irradiated with 200eV D ions at 300323 K have been measured up to a depth of 7 pm using the D(He-3,p)(4) He nuclear reaction in a resonance-like technique. The proton yield as a function of incident He-3 energy was measured and the D depth profile was obtained by deconvolution of the measured proton yields using the program SIMNRA. The depth at which deuterium is retained can be tentatively divided into three zones: (i) the near-surface layer (up to a depth of similar to 0.2 mu m), (ii) the sub-surface layer (from similar to 0.5 to similar to 2 mu m), and (iii) the bulk (> 5 mu m). Low-energy D ion irradiation modifies the W structure to depths of up to about 5 pm, both for W single crystals and polycrystalline W. Up to this depth trapping sites are created at a fluence of 5 x 10(22)/m(2) for the retention of deuterium at about 0.1 at.%. (c) 2004 Elsevier B.V. All rights reserved.