Deuterium retention in beryllium, molybdenum and tungsten at high fluences

Abstract

The retention of 1 keV D in room-temperature beryllium, molybdenum and tungsten has been measured as a function of fluence, for incident D 3 + fluences ranging from 10 21 to 10 25 D/m 2. The amount of D retained in Be tends to saturation (∼ 2.7 × 10 21 D/ m 2) for incident fluences > 10 22 D/ m 2, with an estimated saturation concentration (based on TRIM vectorized for multicomponent targets, TRVMC, range calculations) of ∼ 0.39 D/ Be within the implantation zone; this retention level is similar to what has been observed for single-crystal graphite, viz, ∼ 2.2 × 10 21 D/ m 2 or ∼ 0.4 D/ C. For fluences greater than about 10 22 D/m 2, the amount of D retained in tungsten also tends to saturation at ∼ 6 × 10 20 D/ m 2. Assuming a maximum ion implantation depth of ∼ 40 nm (as calculated by TRVMC), this amounts to a concentration of ∼ 0.24 D/ W. The amount of D retained in Mo does not appear to reach saturation over the fluence range studied. D retention in Mo is lower than that in W for incident D fluences ≲ 10 25 D/ m 2, at which point the two retention curves cross.