ION-IMPLANTATION OF DEUTERIUM IN TUNGSTEN

Re-emission, accumulation and thermodesorption of deuterium in tungsten during ion bombardment were investigated in this work. The re-emission rate during ion implantation increased with fluence approaching a stationary level. Re-emission of heterogeneous molecules HD along with D-2 was observed. The quantity of accumulated deuterium increased as a square root of ion fluence at high fluence due to diffusion into bulk. Thermodesorption spectra consisted at least of four peaks with T-m from 350 to 750 K and were presumably connected with deuterium trapped in defects. Re-emission experiments were described by a model taking into account deuterium diffusion, trapping in defects and associative desorption from the surface. The three processes involved were shown to be determined by thermal activation but not irradiation.