Simplified tritium permeation model

In this model I seek to provide a simplified approach to solving permeation problems addressed by TMAP4. I will assume that there are m one-dimensional segments with thickness Li, i = 1, 2, hor-ellipsis, m, joined in series with an implantation flux, Ji, implanting at the single depth, δ, in the first segment. From material properties and heat transfer considerations, I calculate temperatures at each face of each segment, and from those temperatures I find local diffusivities and solubilities. I assume recombination coefficients Kr1 and Kr2 are known at the upstream and downstream faces, respectively, but the model will generate Baskes recombination coefficient values on demand. Here I first develop the steady-state concentration equations and then show how trapping considerations can lead to good estimates of permeation transient times