TRANSFORMATION OF A LINEAR WAVE BY A LOCAL NONLINEAR ELEMENT

We consider the scattering problem for the D'Alembert equation with a local nonlinear sine term, which is a simplest model of a dispersionle ss transmission line with an inserted Josephson junction. The incident wave is taken in the purely ac form. We demonstrate that, when its am plitude exceeds a certain threshold that depends upon the value of a c oefficient in front of the nonlinear term, the transmitted and reflect ed waves contain both ac and de components, the latter meaning a nonze ro mean value of the time derivative.