Micro- and nano-scale damage on the surface of W divertor component during exposure to high heat flux loads with He

Micro- and nano-scale surface damage on a W divertor component sample exposed to high heat flux loads generated with He atoms has been investigated through SEM, EBSD, AFM and FIB-SEM. The component sample was supplied by the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) and AT&M company, China, and the loading experiment was performed in the GLADIS facility at IPP Garching, Germany. Two typical damage structures were observed on the surface: the first one is characterized by obvious blisters and some grooves formed from ruptured blisters, and the other one is a kind of porous structure accompanying with at least similar to 25 nm surface material loss. As the grain orientation is further away from < 111 >, the damage morphology gradually changes from the former structure to the latter. The possible damage mechanism is discussed. (C) 2015 Elsevier B.V. All rights reserved.