A NEUMANN BOUNDARY VALUE PROBLEM IN TWO-ION ELECTRO-DIFFUSION WITH UNEQUAL VALENCIES

In prior work, a series of two-point boundary value problems have been investigated for a steady state two-ion electro-diffusion model system in which the sum of the valencies v(+) and v(-) is zero. In that case, reduction is obtained to the canonical Painleve II equation for the scaled electric field. Here, a physically important Neumann boundary value problem in the generic case when v(+) + v not equal 0 is investigated. The problem is novel in that the model equation for the electric field involves yet to be determined boundary values of the solution. A reduction of the Neumann boundary value problem in terms of elliptic functions is obtained for privileged valency ratios. A topological index argument is used to establish the existence of a solution in the general case, under the assumption v(+) + v(-) <= 0.