Blister bursting and deuterium bursting release from tungsten exposed to high fluences of high flux and low energy deuterium plasma

Shu, Wataru; Wakai, Eiichi  ; Yamanishi, Toshihiko

Deuterium retention and blistering in the near-surface region of tungsten exposed to high fluences (up to 10D/m) of high flux (10 D/m/s) and low energy (38 eV) deuterium plasma were studied with scanning electron microscopy (SEM), thermal desorption spectroscopy (TDS) and atomic force microscopy (AFM). Peculiar phenomenon of blister bursting with a tail, or a small hole or a vanished cap was found on some grains after plasma exposure or TDS experiment. In addition, bursting release of deuterium with sudden peaks was also found in the TDS spectra below 700 K at the heating rate of 0.5 K/s. A new model called "step-cascade model" was proposed to explain the phenomena of blister bursting with a tail, a small hole and a vanished cap, respectively. Finally, the origin of deuterium retention and blistering as well as the future work on high-Z materials were discussed.