Deuterium retention in helium-irradiated tungsten

Abstract

Hot-rolled tungsten samples were first irradiated with helium ions with varying fluences or energies and then exposed to deuterium plasmas, and the influence of helium fluence (corresponding to damage levels of 0.12–2.3 dpa) and helium ion incident energy (50, 200, 400 keV) on deuterium retention were investigated. A significant increase of the total deuterium inventory was observed in the helium irradiated sample, and deuterium retention reaches saturation at 0.69–1.15 dpa. Radiation-induced defects and helium-vacancy complexes or helium bubbles contribute to the increase of deuterium inventory, and the effect of helium-vacancy complexes or helium bubbles is aggrandizement with the increase of damage level. Comparison of deuterium depth profiles of samples irradiated by helium ions with different incident energies reveals that the vast majority of deuterium is trapped in the helium accumulation region, and the depth of the maximum deuterium concentrations is consistent with the maximum helium concentrations rather than the damage levels. Furthermore, the total amount of deuterium increases with the increase of helium ions energy due to the deepening of the irradiation region.