ESTIMATION OF PERMEATION PROBABILITY IN PLASMA DRIVEN PERMEATION

Hydrogen permeation experiments were carried out with different thickn ess of Ni membranes; 20, 50 and 200 mu m, pre-conditioned for the same surface conditions. Hydrogen plasma was created by ECR heating and pl asma driven permeation (PDP) through the Ni membrane of 523 K was inve stigated. With gas driven permeation (GDP) experimental data, recombin ation coefficients of the upstream and the downstream surfaces (m(4) s (-1)) were calculated; 1.6 x 10(-29) less than or equal to K-1, 7.9 x 10(-30) < K-2 less than or equal to 1.6 x 10(-29). The permeation rate and its probability were estimated by changing K-1 as a parameter. Ab out 20% of tritium permeation probability; equivalent to approximate t o 2 Ci m(2) s(-1), was expected when low energy (approximate to eV) tr itium plasma was discharged at 1.33 Pa and 10 mu m Ni membrane of 523 K, pre-conditioned for reducing K-1 by two orders of magnitude, was em ployed as a tritium membrane pump. (C) 1998 Elsevier Science S.A. All rights reserved.