Response of HTSC ceramics to the electromagnetic signal in the presence of dc magnetic field

Abstract

A temporal dependence of an electric field on the surface of a superconductor sample was studied theoretically and experimentally. The superconductor is placed in an external longitudinal magnetic field and irradiated by a radiowave. An expression for the electrical field E( t) on the sample surface is obatined for arbitrary from of dependence of a critical current density on the magnetic field. The function E( t) contains complete information about the superconductor critical state and the anomalies of magnetic flux penetration into the bulk of the sample. A simple contactless method, based on measurements of the field E( t), is suggested to determinate the three parameters of the critical state: magnetic susceptibility μ, characteristic scale B ∗ of the critical current density varying, and critical current density j 0 with no magnetic field