Superconducting stripline model of intergranular flux penetration

Abstract

A stripline model is successfully applied to an analysis of the surface impedance of a granular superconductor. When the core of the stripline is a resistively shunted Josephson junction, the surface resistance increases with the square of the frequency. A DC magnetic field increases the Josephson inductivity, leading to increased surface resistance and flux penetration. Critical flux penetration of the granular surfaces bordering the junction leads to critical behavior of the stripline. At high power level, a DC magnetic field similarly increases the Josephson inductivity with further increase in surface impedance.