Deuterium retention in single crystal tungsten

Abstract

The retention of deuterium in single crystal tungsten (SCW) has been measured at 300 and 500 K, as a function of incident ion fluence over the range 10 21–10 24 D +/ m 2 . Irradiation of SCW with 1.5 keV D 3 + ions at 300 K leads to saturation at a much lower incident fluence than seen in polycrystalline tungsten (PCW), but with the same levels of D retention at saturation, ≈5×10 20 D/ m 2 . Implantations at 500 K reached saturation at a very low incident fluence, below 10 21 D +/ m 2 , with the amount of D retained at saturation ≈1.5×10 20 D/ m 2 . This level is 3–4 times lower than the saturation value for 300 K implantation of the same single crystal of tungsten. Deuterium depth profile analysis by secondary ion mass spectrometry (SIMS) shows D trapping primarily within the 500 eV D + ion implantation range for both 300 and 500 K profiles. SIMS also revealed that the depth profiles for oxygen and deuterium were similar. When the tungsten was annealed at 500 K for 1 h after implantation at 500 K, SIMS indicated that the deuterium retention decreased by an order of magnitude.