Retention and Recycling of Deuterium in Liquid Lithium-Tin Slab Studied by First-Principles Molecular Dynamics

Abstract

Understanding the retention and recycling of hydrogen isotopes in liquid metal plasma-facing materials such as liquid Li, Sn, and Li-Sn are of fundamental importance in designing magnetically confined fusion reactors. We perform first-principles molecules dynamics simulations of liquid Li-Sn slab with inserted D atoms to provide microscopic insights into the interactions of D with Li-Sn liquid metal. We observe evaporation of D 2 and LiD molecules out of the Li-Sn slabs. With detailed analysis, we unveil a cooperative process of forming D 2 molecules in liquid Li-Sn, where Li atoms act as catalytic centers to trap a D atom before another D comes nearby to form a molecule, and the surplus charges are transferred from D 2 to nearby Sn atoms. Furthermore, we predict a temperature window in which D 2 molecules can escape to vacuum, while LiD molecules cannot.The above findings deepen our understanding of interactions between hydrogen isotopes and Li-Sn liquid metal.