HTSC CERAMICS RESPONSE TO ELECTROMAGNETIC SIGNAL IN THE PRESENCE OF DC MAGNETIC-FIELD

The time dependence of electric field E at the surface of HTSC ceramic s samples of the critical state is studied both theoretically and expe rimentally. The superconductors are placed in external longitudinal ma gnetic field and irradiated by a finite amplitude radio wave. An expre ssion for E(t) is derived with an arbitrary dependence of critical cur rent density in magnetic inductance. The function E(t) contains a comp rehensive information on critical state of the superconductor and on p eculiar penetration of magnetic flux deep into the sample. A simple co ntact-free method based on measuring E(t) is proposed to determine the HTSC sample critical parameters.