A model of the W/Cu interface in the ITER cooling monoblocks from density functional theory

Abstract

ITER divertor is built with tungsten monoblocks that contain a tungsten–copper interface. There, hydrogen isotopes could possibly accumulate leading to safety and mechanical issues. As a consequence, the tungsten–copper interface has to be modeled and characterized, which is here performed at the atomic-scale by means of density functional theory calculations. In order to build the model, we selected the tungsten and copper orientations that minimizes the mismatch between both networks; this results in the W(001)/Cubcc(001) and W(001)/Cufcc(001)R45° interfaces. After relaxation, both systems converge to the same Wbcc(001)/Cuhcp(112̄0) structure, which is consistent with previous experimental observations. Such reconstruction of the copper network has the effect of changing the charge density in the copper part of the interface, with possible effects on hydrogen interaction.

Keywords

• Interface
• DFT
• Reconstruction
• Charge density