A study of the magnetic field distribution in an Ag-sheathed Bi2223 tapeusing scanning Hall sensor and magneto-optical techniques

Abstract

Using both magneto-optical (MO) and scanning Hall sensor techniques,magnetic field distributions have been observed in a superconducting Ag-sheathedBi2223 monofilamentary tape in the presence of an external magnetic field.Application of the inversion scheme to the MO contrast has allowed thetwo-dimensional current distribution to be determined. The Hall sensormeasurements indicate that the current distribution in the core depends on theapplied external field, and the current flows mainly at the edge of the core ina high external field. The magnetic line profiles across the width of the tapehave been analysed by a numerical calculation by modelling the current loopsbased on the two-dimensional current distribution from the MO image. Theanalysis shows that an increase in the external field limits and narrows thecurrent flow region from the whole of the core to the edge.