Energy-dependent study on H retention and desorption behavior on α-Fe surfaces

• H depth distribution is well fitted by a log-normal function. • Plate-like H clusters can form under high local hydrogen concentration. • Plate-like H Cluster formation significantly suppresses hydrogen diffusion toward the surface. • High hydrogen reflection rate enhances desorption of adsorbed H. In this study, molecular dynamics simulations were performed to systematically investigate the implantation and desorption behavior of hydrogen (H) on three α-iron (Fe) surfaces: (100), (112), and (110), under projectile energies ranging from 10 to 100 eV. It is found that H retention increases with increasing projectile energy. This trend is attributed to the positive correlation between the average implantation depth and the projectile energy. Moreover, the implanted H tends to aggregate into plate-like structures, which further hinder its diffusion toward the surface. We conducted a detailed analysis of the desorption mechanisms of adsorbed H and found that the amount of desorbed H is negatively correlated with the projectile energy. This phenomenon is attributed to the fact that lower projectile energies lead to increased reflection rates, and the reflected H facilitate the desorption of adsorbed H. These findings provide important insights into the microscopic mechanisms of H desorption under fusion-relevant conditions.