Deuterium retention and morphological modifications of the surface in five grades of tungsten after deuterium plasma exposure

Five tungsten (W) grades were simultaneously exposed to deuterium (D) plasma with 1020 D/(m2 s) of 38 eV/D up to 1026 D/m2 at 500 K specimen temperature. The D inventories and their depth profiles within the topmost 12 μm were determined by nuclear reaction analysis (D(3He, p)α). Morphological modifications at and below the surface were analysed by confocal laser scanning microscopy and scanning electron microscopy assisted by focused ion beam cross-sectioning. The observed variation of the D inventory by more than one order of magnitude (0.5-15 × 1020 D/m2) is attributed only to the different properties of each W grade. Spherical blisters and stepped flat-topped extrusions are observed depending on the W grade. These modifications are interpreted as an indication for hydrogen loading-induced damaging. The exposure conditions and W grades were chosen to allow a comparison between published data sets.