The boundary conditions are obtained for NS interface at the presence of arbitrary concentrations of nonmagnetic impurities. The current states in SNS junction are considered. The solution obtained for the current is analysed, in particular it was found out how the characteristic length of the current decreasing ξ 0 for pure superconductor turns to ξ d for dirty one. A variant of the variational method, called the method of quasiorthogonality to asymptotics, is used to obtain the boundary conditions.

The behavior of the order parameter close to the superconductor-normal metal interface is researched. The thickness d of the normal layer is arbitrary and the temperature is close to critical. The method of quasiorthogonality to asymptotics is used to obtain boundary conditions. The expression that describes the dependence of the current states on the normal layer's thickness is obtained. Asymptotic forms of solution at large and at small d (relatively to the coherence length) are considered.