Modeling the trapped field distribution in a polycrystalline bulk superconductor based on a critical state model

Abstract

The trapped field distribution of a polycrystalline bulk superconductor induced by perpendicular magnetic field is theoretically analyzed based on the critical state model. A rational model is presented to describe the current pattern changes near a low-angle grain boundary (GB) that is observed in others’ experiment. The current pattern that varies with the ratio between GB critical current density and grain critical current density is analyzed based on the constant critical current density assumption. In addition, the magnetic field that trapped in the prism both on magnetization ascent and descent stage have been discussed in detail on the basis of the current distribution that we deduce above. The results of this work can also be useful for AC loss analysis and stress calculating of polycrystalline superconductors.