2010.05.21

工学部4号館１階 205セミナー室

Prof. Guang-Hong Lu
       Department of Physics
       Beijing University of Aeronautics and Astronautics

題目：Understanding Physical Origin of Hydrogen/Helium and Tungsten Interaction via an Optimal Charge Density

内容の概要説明：
Tungsten (W) is considered to be a promising candidate for the first-wall and divertor plate in fusion reactors. He irradiation is one of the key concerns for W PFM and has been under intensive investigations. We reveal the microscopic vacancy trapping mechanism for H bubble formation in W with vacancy defect, which provides an isosurface of optimal charge density that induces collective H binding on its internal surface, a prerequisite for the formation of H2 molecule and nucleation of H bubble inside the vacancy.

The local lattice expansion induced by the presence of interstitial He atom leads to the local optimal charge density decreasing. This makes interstitial He act as a trapping center for H in W. He-vacancy (He-V) can hold much more H atom than a monovacancy. However, the H trapping energy of He-V complex is lower than that of a monovacancy by 0.18 eV. Significantly, the existence of He can suppress the formation of H2 in a vacancy, because the prerequisite space for the formation of H2 molecule is occupied by He. This provides effective approaches to suppress the formation of H bubbles in PFMs.

日時：2010年5月21日（金） 15:15 ～16:15

場所：東京大学工学部4号館１階 205セミナー室

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