Suppressed D retention by H Co-implantation in RAFM steels: coupling effects of H + D mixed plasma and displacement damage

• Heavy-ion irradiation significantly enhances D retention in CLF-1 steel, which reaches a saturation plateau above ∼1 dpa. • Radiation-induced defects serve as stable traps, manifesting as a distinct high-temperature desorption peak absent in undamaged samples. • The co-introduction of H effectively suppresses D retention across all investigated damage depths. • This H-induced suppression is primarily governed by defect type rather than damage depth. The deuterium (D) retention in reduced-activation ferritic/martensitic (RAFM) steels under simultaneous hydrogen (H) and D plasma exposure was investigated, with a focus on the coupling effects of pre-existing displacement damage. Controlled damage profiles were introduced via heavy-ion irradiation using 4.5 MeV and 387 MeV Fe ions. The results indicate that heavy-ion irradiation significantly enhance D retention and induce high-temperature desorption above 1000 K. Crucially, the co-introduction of H effectively suppresses D retention, especially in the high-temperature regime. These findings imply that in a D-tritium (T) fusion environment, the co-existence of multiple hydrogen isotopes may naturally mitigate T retention, offering positive implications for T management and safety in future fusion reactors.