Fusion Science and Technology / Volume 52 / Number 3 / October 2007 / Pages 613-617
Technical Paper / First Wall, Blanket, and Shield
In order to understand the capability of vanadium panels and membranes for fuel particle pumping at relatively low temperatures, absorption of neutral hydrogen atoms by vanadium sheet was examined at/below 350 °C under wide variety of experimental conditions. A niobium sheet kept at high temperature (420 °C) was used as a reference specimen. Sufficiently high absorption rates were obtained even at around room temperature in the range of incident fluxes from 1017 to 1021 m-2s-1. No noticeable reduction in absorption rates was observed up to the H retention level of 0.1 at%. The influence of CO and water vapor was negligibly small up to an exposure of 1023 m-2. Significant reduction in the absorption rate was observed only when an oxide film was formed on the surface by exposure to O2 to 1020 m-2 and to H2O over 1023 m-2 at room temperature.