ヘリウム・プラズマ照射によって誘起された金属表面の繊維状ナノ構造形成機構に関する考察

Abstract

"Fiber-form nanostructure on tungsten surface induced by helium plasma exposure found for the first time by the author has a fuzzy surface morphology so that the physical mechanism on its growth is widely attracted by many researchers in addition to a new worry in plasma-surface interaction in magnetic confinement fusion energy development. Experimental, theoretical and numerical simulation approaches are developed in these more than ten years. However, we do not obtain definitive explanation for this interesting phenomenon. The author has developed a special experimental technique ?flux gradient method ? which converts time evolution of growth to a spatial extension on substrate. It reveals that a loop-like structure would be a precursor for fuzz formation on tungsten as well as molybdenum surfaces. The importance of shear modulus of tungsten with helium content and its temperature dependence was identified as an essential key for fiber-form nanostructure formation. The meaning of temperature band for the formation is discussed, pointing out a competition between formation and annihilation of fibers near the upper limit of temperature band for the formation."