Vacancy-Dependent Bulk and Surface Retention of Hydrogen Isotopes in Tungsten—A Molecular Dynamics Study

Tungsten, given its high heat and neutron resistance, is often the material of choice for plasma-facing components in nuclear fusion reactors. However, understanding and predicting the behavior of hydrogen isotopes (deuterium and tritium) within tungsten's lattice poses a significant challenge. The retention and diffusion of these isotopes, which are influenced by microstructural defects such as vacancies, can significantly impact the performance and safety of fusion devices. This article employs the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) simulation package to analyze the behavior of hydrogen isotopes in tungsten lattices with varying vacancy densities. Simple relationships between penetration depth and energy and mass of hydrogen isotope, as well as between reflection/penetration ratio, are found. The effect of vacancies on isotope diffusion and retention in the material and the role of temperature in this process are investigated.