Molecular dynamics simulation of deuterium trapping and bubble formation in tungsten

The interaction between plasma particles and tungsten as plasma facing material is one of the critical issues in successfully using tungsten in Tokamak reactors environment. The deuterium bombardment of monocrystalline tungsten was modeled by molecular dynamics simulation using LAMMPS code and Tersoff type interatomic potential. The deuterium trapping rate, implantation depth, and the stopping time in tungsten at several temperatures ranging from 600 to 2000 K bombarded by 5–100 eV deuterium atoms were simulated. Deuterium bubble formation at near tungsten surface was also studied. Irradiated monocrystalline tungsten became amorphous state prior to deuterium cluster formation, and gas bubbles were observed in the 600, 900, and 1200 K tungsten samples. The formation of gas bubbles were caused by the near surface deuterium super-saturation region and the subsequent plastic deformation induced by the local high gas pressure.

► Deuterium tungsten interaction was simulated using classical molecular dynamic methods.
► Low energy deuterium atoms tend to affix to high temperature tungsten surface.
► Tungsten substrate temperature barely affects the low energy deuterium implantation depth.
► Deuterium bubble formation resulting from near surface super-saturation was predicted.