Comparison of deuterium retention in EUROFER97 after gas and plasma loading

Understanding the mechanisms governing tritium retention in structural materials, such as EUROFER97, 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 D₂ gas at various temperatures. 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. These findings provide new insight into D behavior in reduced activation ferritic/martensitic (RAFM) steels, with direct implications for tritium retention in reactor environments.