Influence of crystal orientation on damages of tungsten exposed to helium plasma

The effect of crystallographic orientation on the morphology change of tungsten (W) has been investigated in the linear plasma device, NAGDIS-I by exposing high density helium plasma to ITER grade W. After helium plasma exposure, the surface of specimens was analyzed by scanning electron microscope and orientation imaging microscope. The internal structure was analyzed with transmission electron microscope after the sample was milled by focused ion beam procedure. A clear difference in the surface morphology was observed on different crystal grains. Regular wavy structure were observed on crystal grains of {001}, {112}, {101}, and {111} surface, but there were no clear wavy structure on the crystal grains of {103}, {102}, {407} and {203}. The experimental results indicate that the angle between a slip face and face of each grains are important to determine the helium induced surface morphology change of tungsten. (C) 2013 Elsevier B. V. All rights reserved.