Comparative studies of helium behavior in copper and tungsten using molecular dynamics simulations

Helium (He) behavior in copper (Cu) and tungsten (W) bulk has been investigated and compared by molecular dynamics simulations. In contrast to the diffusion of He in W, interstitial He and He2 in Cu have higher diffusion coefficients and lower migration energies, which causes He atoms to rapidly coalesce into helium clusters. Once a Hen cluster (n ≥ 3) forms, trap mutation occurs in a short time. W atoms are less likely to be projected by Hen clusters. The binding energies are calculated to prove the results. For He2 in Cu, the dissociation of He2 and trap mutation both occur above 700 K. The total phenomenon exhibits Arrhenius behavior. The effective capture radii (ECRs) of an interstitial He trapping another one in Cu are obtained, which differ slightly from that in W. They decrease as the temperature increases, which deserves more attention, as the ECRs are required in MC and RT models.