Comparison of deuterium retention in EUROFER97 after gas and plasma loading

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Abstract Understanding the mechanisms governing tritium retention in structural materials is essential for ensuring both safety and tritium self-sufficiency in future fusion reactors. In this work, EURORFER97 samples were exposed either to a low energy electron-cyclotron-resonance deuterium (D) plasma or to D 2 gas at various temperatures. Post-exposure, D depth profiles within the first 7 μ m were measured using nuclear reaction analysis with a 3 He beam while thermal desorption spectroscopy was employed to determine the total retention and desorption behavior. Clear differences emerged between plasma and gas exposures: plasma loading resulted in a single dominant low-temperature desorption peak, whereas gas loading resulted in additional peaks at higher temperatures. These experimental results were simulated using a state-of-the-art reaction-diffusion code (TESSIM-X) to derived de-trapping energies and trapping barriers. The results indicate the presence of traps with high-energy barrier for entering the trap, whose occupation strongly depends on the solute D concentration. Additionally, re-polishing the sample surface after D 2 gas exposure significantly reduced the amplitude of the low-temperature desorption peak, while the high-temperature peak remained largely unchanged. These findings provide new insight into D behavior in reduced activation ferritic/martensitic steels, with direct implications for tritium retention in reactor environments.

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