Blister formation on tungsten surface under low energy and high flux hydrogen plasma irradiation in NAGDIS-I

This study presents experimental results on hydrogen blister formation on powder metallurgy tungsten (PM-W) surface under low energy (<100 eV) and high ion flux (>1021 m-2 s-1) hydrogen plasma irradiation in a divertor plasma simulator-NAGDIS-I. The tungsten samples were exposed to steady-state hydrogen plasma at various sample temperatures and fluences. Hydrogen blister formations are clearly observed on tungsten surface at the surface temperature below 950 K. The blister size is from a few 10 μm to a few 100 μm. It was found that the blister formations obviously depend on the surface temperature and the incident hydrogen ion fluence. No blisters are observed on tungsten surface at the surface temperature above 950 K even if the fluence is high enough