An insight view of Helium trapping and diffusion in plasma-facing materials through molecular dynamics study

Comprehensive understanding of plasma facing materials under extreme conditions of high temperatures and high particle flux is critical to reach the goal of building commercial scale fusion power plants. Recent announcements from the ITER team of using tungsten for the first wall and divertor regions have sparked more studies to be focused on understanding the behavior of tungsten and tungsten alloys exposed to fusion environments, whether at steady-state or transient conditions. A recent study done from our group (CMUXE) investigating the effects of various ELM-like plasma events on a tungsten-tantalum alloy reveals valuable insights into the behavior of W-Ta alloys such as surface morphology, erosion and subsurface changes under ELM-like plasma conditions. In this study, helium bombardment with 100 eV on tungsten and tungsten-tantalum structures at various temperatures was analyzed using MD methods. LAMMPS code was employed using the EAM interatomic potential for determining the interaction between particles. The effect of structure temperature on helium trapping mechanism parameters such as retention and implantation distribution were analyzed. Our preliminary results show that the temperature dependence of Helium’s retention rate showing differences between pure W and W-Ta alloy. The goal of this study is to provide comprehensive understanding and comparison of He trapping mechanism in W and W-Ta to determine the potential pros and cons on the overall performance in future fusion devices.