ION-DRIVEN PERMEATION AND SURFACE RECOMBINATION COEFFICIENT OF DEUTERIUM FOR ION

The steady-state flux of deuterium permeation through an iron membrane (99.99 + % purity, 0.14 mm thickness) driven by a deuterium ion beam (5 keV D3+, 1.0 x 10(15) D-atoms cm-2 s-1) was measured in the range o f 30-1050-degrees-C. The permeation flux increased with increasing tem perature above 200-degrees-C whereas it was roughly constant below 150 -degrees-C. Such temperature dependence was observed for nickel and co pper as well, and has been ascribed to the transition in the rate-limi ting processes of the deuterium transport in the membrane. The recombi nation coefficient of deuterium on iron surface was evaluated from the permeation flux density. In the case of alpha-iron, the evaluated val ue agreed with a semitheoretical one estimated using literature data o f adsorption probability and solubility. This agreement indicates that the release kinetics reflects the activation barrier for hydrogen (de uterium) adsorption.