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Previous study results show that He nanobubble has great effectiveness on reducing deuterium (D) retention by acting as D diffusion barrier in undamaged commercial ITER grade tungsten (W), however, this effect on radiation damaged tungsten has not been extensively studied. In this paper, He plasma exposure (ion flux: 1023 m-2 s-1, fluence: 1025 m-2) pre-treatment was performed to create a thin He nanobubble layer in tungsten at ~773 K, after which these samples were irradiated by 5 MeV Cu ions or 5 MeV C ions to induce average peak dpa of 0.001 to 0.1 at room temperature. Samples without He plasma exposure pre-treatment were irradiated by Cu or C ions at the same time. All the samples above were subsequently exposed to D plasma at 350 K to a fluence of 1026 m-2. Nuclear reaction analysis (NRA) was used to evaluate the D distribution profile in the near surface, while the total D retention was measured by thermal desorption spectroscopy (TDS). Possible mechanisms are proposed to interpret the experiment results.
| Eligible for student paper award? | No |
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