Estimation of permeation probability in plasma driven permeation

Hydrogen permeation experiments were carried out with different thickness of Ni membranes; 20, 50 and 200 μm, pre-conditioned for the same surface conditions. Hydrogen plasma was created by ECR heating and plasma driven permeation (PDP) through the Ni membrane of 523 K was investigated. With gas driven permeation (GDP) experimental data, recombination coefficients of the upstream and the downstream surfaces (m4 s−1) were calculated; 1.6×10−29≤Kl, 7.9×10−30<K2≤1.6×10−29. The permeation rate and its probability were estimated by changing K1 as a parameter. About 20% of tritium permeation probability; equivalent to≈2 Ci m2 s−1, was expected when low energy (≈eV) tritium plasma was discharged at 1.33 Pa and 10 μm Ni membrane of 523 K, pre-conditioned for reducing K1 by two orders of magnitude, was employed as a tritium membrane pump.