Absorption of Atomic Hydrogen by Vanadium

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.}