FEATURES OF THE NONLINEAR-INTERACTION OF ELECTROMAGNETIC-WAVES IN HTSC CERAMICS

The nonlinear interaction of electromagnetic waves in an HTSC plate in the critical state is studied both theoretically and experimentally. The magnetic components of both waves are collinear and parallel to th e plate surface. We have considered two radiowaves having different fr equencies and have predicted and experimentally observed jumps of the electrical field E(t) on the plate surface which take place owing to t he nonlinear wave interaction. Besides, we have investigated the behav iour of the nonlinear surface impedance at low frequencies as a functi on of the radiowave amplitudes. The unusual non-monotonous dependence of the surface impedance (both real and imaginary components) on the r adiowave amplitudes has been obtained. The character of the magnetic f ield dependence of the critical current density significantly influenc es the lineshape of the E(t) curves. Therefore, one can obtain informa tion on this dependence from the results of E(t) measurements.