An ab-initio study of hydrogen trapping energetics at BCC tungsten metal-noble gas interfaces

Density functional theory (DFT) calculations have been performed to assess the trapping and segregation strength of hydrogen (H) to noble gas interfaces in tungsten (W). These calculations consist of a super-cell containing a slab of BCC W and an initial lattice of FCC noble gas atoms. The interfaces included noble gases of helium, neon, and argon, with densities in the range of 1-4 atoms-per-vacancy (V), and W surface orientations of (100), (110), and (111). We report on the binding energy of H to these interfaces as well as the modification to the migration barriers in the W slab, which together provide information on the segregation strength and de-trapping energy for H at noble gas bubbles. These calculations indi-cate that the binding energy of H to W-noble gas interfaces varies with surface orientation and decreases with increasing gas density; whereas the H migration energy is sensitive to the noble gas density, surface orientation, and diffusion pathway, and typically increases with gas density. Together, the de-trapping energy of H to these interfaces is shown to depend less significantly on noble gas density. These DFT cal-culations provide valuable first-principles energetics necessary for mesoscale models, and provide insight into the temperatures required to de-trap tritium from He bubbles in fusion plasma facing components. Published by Elsevier B.V.

Automated summary

Density functional theory (DFT) calculations have been used to study the trapping and segregation strength of hydrogen at noble gas interfaces in tungsten, revealing variations in binding energy and migration energy with noble gas density and surface orientation. The de-trapping energy of hydrogen at these interfaces was found to be less sensitive to noble gas density.