Deuterium retention in tungsten damaged with W ions to various damage levels

• W samples were pre-irradiated with 4.8 and 20 MeV W ions to various displacements per atom (dpa).
• Under following exposure to D plasmas radiation-induced defects were occupied by diffusing D atoms.
• At ⩾0.1 dpa, the D concentration in the damage zone demonstrated weak dependence on the damage level.

W samples were irradiated at 300 and 573 K with 4.8 and 20 MeV W ions to displacement damage levels in the range from 0.022 to 50 displacements per atom at the damage peak. 50 μm thick W samples were exposed to high flux D plasma at 550 K on the side opposite to the damaged one, whereas 2 mm thick W samples were exposed to low flux D plasma at 403 K on the damaged side. Trapping of deuterium at displacement damage was examined by the D(3He, p)4He nuclear reaction with 3He energies between 0.69 and 4.0 MeV allowing determination of the D concentration up to a depth of 6 μm. It was found that (i) at the damage level above 0.1 dpa, the concentration of the W-ion-induced defects responsible for trapping of diffusing D atoms depended very weakly on the numbers of displacements per atom, and (ii) the quasi-saturation concentration of the defects decreased by a factor of two as the W-ion irradiation temperature increased from 300 to 573 K.