Effect of irradiation damage profile on hydrogen isotope retention behavior for neutron irradiated tungsten

Fujita, Hiroe*; Yuyama, Kenta*; Uemura, Yuki*; Sakurada, Shodai*; Hu, C.*; Chikada, Takumi*; Oya, Yasuhisa*; Ota, Masayuki; Ochiai, Kentaro

Tungsten (W) is the candidate for the plasma facing material in D-T fusion reactors. The distribution of defects introduced by neutron irradiation is formed uniformly throughout the bulk, while that by heavy-ion irradiation is concentrated in the shallow region near the surface. Therefore, it is expected that the hydrogen isotope behaviour in neutron irradiated W would be different from that in heavy-ion irradiated W. In this study, the irradiation defects were introduced by Fe irradiation, fission neutron irradiation and 14 MeV neutron irradiation from D-T fusion reaction. After the irradiation, the deuterium ions (D) implantation was performed and the D retention behaviour was evaluated by thermal desorption spectroscopy (TDS). The experimental results indicate that stable trapping sites would be formed into W by 14 MeV neutron irradiation with lower neutron fluence, on the other hand, only low energy trapping sites will be formed by fission neutron irradiation.