The effect of displacement damage on deuterium retention in tungsten exposed to D neutrals and D2 gas

Abstract

Abstract Samples of polycrystalline ITER-grade W and recrystallized W were irradiated at room temperature with 20 MeV W ions to displacement damage up to 0.5 dpa. The damaged W samples were then exposed to (i) D neutrals at 403–573 K and (ii) D 2 gas at 673–1073 K and pressures of 1.2 and 100 kPa. Trapping of deuterium in the damage zone was examined by the D( 3 He, p) 4 He nuclear reaction with 3 He energies between 0.69 and 4.0 MeV allowing determination of the D concentration up to a depth of 6 μm. It has been found that generation of the W-ion-induced displacement damage leads to accumulation of deuterium in the damage zone up to concentration depending on the exposure temperature and, at temperatures ⩾673 K, on the D 2 gas pressure. Thermal desorption spectra allowed a conclusion that deuterium is mainly accumulated in the form of D atoms bound to inner walls of vacancy clusters.