Ratio of specimen thickness to charging area for reliable hydrogen permeation measurement

AbstractTwo-dimensional diffusion of hydrogen atoms in a membrane has been analysed. The hydrogen atoms are assumed to be generated in a circular area on one side of the membrane and detected in a circular region on the opposite side. The average flux on the detection side has been calculated as a function of membrane thickness and detection area and compared with the prediction from the conventional one-dimensional solution. The applicability of the latter increases with decreasing ratios of thickness and detection area to charging area. Recommendations are given for reliable use of the one-dimensional analysis.