DISTRIBUTION-FUNCTIONS IN A NORMAL-METAL-SUPERCONDUCTOR JUNCTION

We compute the distribution functions of a normal-metal-superconductor junction, while taking into accounts the effects of Andreev reflectio n and impurity scattering. It is possible to obtain an analytic soluti on of distribution functions at a low concentration of impurities. The phase coherence between the incident electrons and the reflected hole s by Andreev scattering extends over distances of the order of the mea n free path. We also compute the electric potential, current density, and the resistivity.