Plasma-driven permeation through superpermeable membranes was investigated, at 910 to 1420K, under bombardment of the input surface with H, D and He ions having energies of up to 250eV. The membrane surface was covered with a non-metallic monolayer. This created a potential barrier which was responsible for the superpermeability to suprathermal H particles. An increase in ion energy, or an increase in the mass of sputtering ions, resulted in a significant decrease in the permeability - due to destruction of the non-metallic monolayer - when the ion energy was higher than the threshold energy for surface film sputtering. On the other hand, an increase in the membrane temperature resulted in a decrease in the ion bombardment effect and an increase in membrane permeability. This was due to recovery of the surface barrier via segregation of impurities, dissolved in the membrane bulk, to the membrane surface. In order to increase the ability of the membrane to recover the potential barrier, O was dissolved in the membrane bulk up to a concentration of 2.5at%. This resulted in a significant decrease in the damaging effect of ion bombardment, and extended the range of membrane temperatures and ion energies within which plasma-driven superpermeability was observed.

Effect of Ion Bombardment on Plasma-Driven Super-Permeation of Hydrogen Isotopes through a Niobium Membrane. M.E.Notkin, A.I.Livshits, A.M.Bruneteau, M.Bacal: Nuclear Instruments and Methods in Physics Research B, 2001, 179[3], 373-82