Influence of Cu/W interfacial structure on the resistance against harmful helium atoms: A mechanism analysis

To improve the service performance of Cu/W plasma-facing components (PFCs), the influence of the Cu/W interfacial structure on the resistance against harmful He atoms, including the He weakening effect and He atom intrusion, was investigated using density functional theory (DFT) calculations. The Cu(100)/W(100), Cu(110)/W(110), and Cu(111)/W(111) were selected as the representative Cu/W interfacial structures. The results show that He atom intrusion at the Cu/W interface weakens the interfacial Cu-W ionic bonding strength and the covalent bonding strength simultaneously, causing a decrease in the Cu/W interface bonding property (He weakening effect). The Cu(111)/W(111) interfacial structure shows the largest resistance to the He weakening effect owing to the minimal reduction of the interfacial work of adhesion similar to 0.45 J/m(2); this is attributed to the lesser weakening degree of the Cu-W ionic bonding strength. Moreover, when He atoms diffuse along the Cu/W interface, the interactions between the He atoms at the saddle point and the surrounding Cu and W atoms on the Cu(111)/W(111) interfacial structure are the strongest. The resulting highest energy barrier of similar to 6.84 eV and the resulting low diffusion coefficient indicate that the Cu(111)/W(111) interfacial structure also has the strongest hindrance capacity against He atom intrusion. Therefore, Cu(111)/W(111) is the most promising Cu/W interfacial structure, which can significantly improve the service performance of the Cu/W PFC. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

The influence of different Cu/W interfacial structures on resistance against harmful He atoms was investigated using density functional theory calculations. The Cu(111)/W(111) interfacial structure showed the greatest resistance to He weakening effect and He atom intrusion, making it the most promising Cu/W interfacial structure for improving service performance.