Molecular dynamics simulation of helium cluster diffusion and bubble formation in bulk tungsten

Abstract Molecular dynamics (MD) simulations have been performed to investigate the diffusion behavior of helium (He) clusters in tungsten (W), because their diffusion properties provide basic knowledge in understanding the He bubble formation. The binding energy between He and He cluster is shown to be positive, and thus, He is easy to form bubbles by self-trapping. The mean squared displacements (MSDs) were employed to determine the diffusivities of He clusters with different sizes at different temperatures. The He bubble formation at different temperatures with 1% He was also investigated. It is revealed that the formation of He bubbles is strongly associated with the temperature and the diffusivities of the He clusters in W. The results demonstrate the initial stage of the He bubble formation and growth in W.