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

Highlights: • D retention for used W grades varies by more than one order of magnitude. • Hydrogen loading-induced damaging manifests in surface modifications and retention. • Effects of plasma flux on retention and surface modifications are discussed. • Higher fluxes produce more severe hydrogen loading-induced damaging. - Abstract: 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