Strong hydrogen trapping at helium in tungsten: Density functional theory calculations

作者：Jiang B; Wan F R; Geng W T^*

来源：Physical Review B, 2010, 81(13): 134112.

DOI：10.1103/PhysRevB.81.134112

Using first-principles density functional theory calculations, we have investigated the interaction of H and He in W, a potential plasma-facing material in fusion reactors. Strong attraction is found between He and H due to a decreased electron density around He. In the vicinity of a substitutional He atom, the H choose to stay in the tetrahedral-, rather than octahedral-interstitial sites. The maximum number of H atoms that one substitutional He can trap is 12, despite a much smaller local open volume than a vacancy offers. The trapping energy to He for the first H is as large as -0.96 eV. Such a strong attraction well explains the observed enhanced retention of H and He near the surface of W under both sequential and simultaneous bombardments. At ideal He/H ratio, He might suppress to a considerable extent the H blistering at the W surface. In a semiquantitative analysis, we decompose the strong He-H interaction into three parts, namely, an attractive force induced by valence electron depletion around He, repulsive forces contributed by elastic compression of the He-H separation and a H-H repelling in high-density electron gas.

• 出版日期2010-4-1
• 单位北京科技大学