Speaker
Description
To limit hydrogen leakages in a breeding blanket of fusion reactor, a hydrogen permeation barrier can be used. Erbium oxide was selected as a promising candidate with a low hydrogen diffusion. Thus, the purpose of this study is to understand the irradiation effect of helium ions, originating from fission of lithium exposed to fusion-induced neutrons in the blanket, on the hydrogen diffusivity of erbium oxide.
To meet this objective, an erbium oxide of approximately 600 nm thickness was deposited on the substrate with the same quality as blanket materials. After division into subsamples, halves were irradiated to 1−3 displacement per atom (dpa) with 0.4 MeV 4He+ from the 1MV Cockcroft-Walton accelerator. The irradiation conditions are chosen so as to meet mathematical models of lithium blanket, in which the stopping and ranges of ions in matters (SRIM) was used for the irradiation damage calculation. The samples were annealed at 773-973 K under hydrogen atmosphere (0.4 bar), as a safe substitute of hydrogen exposure. Through the nuclear reaction analysis of hydrogen, we will be able to obtain the depth profile of diffused hydrogen during the annealing period, from which information on the diffusivity for different samples is obtainable. Influence of irradiation on the hydrogen diffusion coefficient of erbium oxide could be quantified for non-irradiated and irradiated samples. Future experiments and analysis are now under way.
In conclusion, the rise of diffusivity due to the irradiation seems serious in blanket operation. In the next stage, the diffusion study will be required using hydrogen itself to assert the promising nature of erbium oxide, together with the structural analysis of irradiated erbium oxide.
