Size distribution of nano-tendril bundles with various additional impurity gases

Abstract

Abstract Nano-tendril bundles (NTBs) are generated on a tungsten surface by helium plasma exposure with various additional impurity gases, such as argon, nitrogen and neon. In this study, the formation condition of NTBs and the effect of incident ion energy, Ei, and impurity gas ratio, λg, are explored in detail. It is found that NTBs are easily formed at where the incident ion flux and fluence is enhanced, such as the periphery of the sample. The confocal laser scanning microscopy reveals that the area and the height distributions of NTBs greatly depend on Ei, which plays a dominant role in determining the birth of new NTBs and the growth of existing NTBs. The number density of NTBs is found to depend on the net erosion yield, Y, regardless of gas species, indicating that the balance between Ei and λg is important for the favorable growth of NTBs. The preferential growth of NTBs in the radius direction appears and the cause of the limited growth in height is discussed.