Surface modification and correlated internal damage in tungsten irradiated with low energy helium ions at 1273 K

Abstract

Surface modification and internal damage of tungsten irradiated with 8keV Helium (He) ions at 1273 K was observed by the complementary use of a scanning electron microscope (SEM), an atomic force microscope (AFM), and a transmission electron microscope (TEM). It was found that an irradiated surface was roughened by the formation of dense large bulges of 100-200 nm and small ones of a few nm in size. It was also observed that fine He bubbles ranging from a few to 100 nm were formed in the subsurface layer. These results indicate that roughening of a He + ion irradiated surface at a high temperature results from the formation of bubbles just beneath the surface. Their thermal migration and coalescence under irradiation play an important role in the formation of various sized bubbles. ©2005 The Japan Institute of Metals.