ヘリウム・プラズマ照射によってタングステン表面に形成される繊維状ナノ構造の結晶性

Abstract

Physical mechanisms of fuzzy nanostructure formation on tungsten material surface irradiated by helium plasma have been extensively studied from both experiments, and modeling and numerical simulation since its finding in 2006. However, the growth mechanism of nano-fibers from the atomistic and crystal points of views is not well understood. In this article, the diffraction techniques of X-ray as well as electron beam are employed for the above mentioned physical mechanism clarification. A new technique of slicing off fuzzy structure from the base tungsten plate provides a clear crystallinity investigation using dark-field scanning transmission electron microscope and diffraction capabilities. In addition, a small angle incident X-ray diffraction technique gives information on intensity distribution among contributions of different crystal orientation families and a difference between surface fuzz layer and the basing tungsten bulk surface with helium defects. Temporal fearless conclusion is that the crystallinity of nano-fibers would be the same as that of bulk α-tungsten although the grain size of nano-fibers is much smaller than those in bulk materials.