Modeling and Simulation of Hydrogen Behavior in Tungsten

Based on national strategic needs for fusion energy, our group have investigated the behavior of H isotopes including dissolution, diffusion, accumulation and bubble formation in W using a firstprinciples method in combination with molecular dynamic method. It is found that the dissolution and nucleation of H in defects follow an "optimal charge density" rule, and a vacancy trapping mechanism for H bubble formation in W has been revealed. An anisotropic strain enhanced effect of H solubility due to H accumulation in W has been found, and a cascading effect of H bubble growth has been proposed. Noble gases/alloying elements doping in W has been proposed to suppress H bubble formation, because these dopants can change the distribution of charge density in defects and block the formation and nucleation of H₂molecule. These works are reviewed in this paper. Our calculations will provide a good reference for the design, preparation and application of W-PFM under a fusion environment.