Interplay between the Edge Dislocation and Hydrogen in Tungsten at Electronically Excited States

Abstract

Under the continuous irradiation of high‐density and high‐energy photons from the plasma core of a fusion reactor, the plasma‐facing materials (PFMs) of tungsten (W) are in electronically excited states. How hydrogen (H) interacts with defective PFMs in an electronically excited state is an open question. The authors report the developed W‐H tight‐binding (TB) potential model and employ this model to systemically investigate the interaction between an edge dislocation in tungsten with H at different electronically excited states. With the enhancement of electronic excitation, the strong attraction of the dislocation core to H slightly fluctuates, while the attraction to H is significantly enhanced in the region outside the dislocation core. When the electronic excitation energy is ≈0.86 eV, the region of tensile stress can trap H without additional energy. Additionally, the electronic excitation simultaneously makes H migration easy. It is revealed that the transfer of partial energy of the excited electrons to the lattice leads to the nonthermal expansion of the system and affects the interaction between the edge dislocation and H. These results not only show the nonthermal effect of tuning the interaction between hydrogen and the edge dislocation in tungsten but also uncover the nature underlying these phenomena.

Electronically Temperature-Dependent Interplay between He and Trivacancy in Tungsten Plasma-Facing Materials

“…To gain deeper insights into the impact of electronic excitation on the ability of V3 to trap He, we decomposed the trapping energy into three components: band structure energy, repulsive energy, and the energy associated with electron entropy. These components correlate with the electronic structure, atomic structure, and degree of electron disorder distribution within the excited system [28,43]. As illustrated in Figure 3, in the specific scenario where the He atom approaches the V3 defect, the sum of the band structure energy and repulsive energy gradually decreases as the electronic temperature increases.…”

“…This suggests that the predominant factor driving the increase in trapping energy is the enhanced electron disorder distribution resulting from electronic excitation. We also decompose the trapping energy into three components: band structure energy, repulsion energy, and electron entropy [28,43]. As depicted in Figure 10, the sum of the band structure energy and the repulsive energy slightly decreases with increasing electronic temperature.…”