Ab initio molecular dynamics simulation of irradiation particles behavior in tungsten

Tungsten (W) is a candidate material for plasma facing materials (PFMs), which is expected to suffer from a high flux of irradiation particles as well as a significant heat load. In the present work, ab initio molecular dynamics (AIMD) simulation is performed to study the irradiation damage of the W lattice and the behavior of the irradiation particles in the W lattice. Both low-energy hydrogen (LoE-H) (52 eV) and high-energy hydrogen (HiE-H) (5.2 keV) irradiations are considered, and low-energy carbon (LoE-C) (56 eV) irradiation is also considered for comparison. It is found that the energy absorption process is much faster for LoE-C irradiation than LoE-H irradiation, due to the much stronger interactions between C atoms and the W lattice. As a result, vacancy defects can be created by C atom irradiation at the surface area. The travelling depth of LoE-H particles is estimated to be about 140 Å, about one order of magnitude larger than that of LoE-C particles (12 Å). It is also found that the behavior of HiE-H particles in the W lattice is completely different to that of the LoE-H. Without considering the direct nuclei collision between the HiE-H and the W nuclei, HiE-H particles move almost linearly in the W lattice within the 1 ps simulation time, and the travelling depth is evaluated to be about 140 μm. HiE-H irradiation damage to the W lattice is not observed in the AIMD simulation, suggesting that damage from HiE-H can only occur during the direct nuclei collision.