Anisotropy of E(I) characteristics of Ag-sheathed BSCCO tapes with respect to external magnetic field

Abstract

Because of the macroscopic form of Ag-sheathed BSCCO-2223 tape conductors, as well as internal structure of grain build up and their mutual orientation within the Ag sheath, their volt–ampere characteristics are not isotropic with respect to external magnetic field orientation. For the same absolute field values the behaviour of E(I) curves are a sensitive gauge of vector B inclination to tape axis and to the surface plane. As a result of the proximity effect and the weak links structure, the increasing external magnetic field reduces overall integral current capacity of the sample. The effect is pronounced at a perpendicular orientation of B but an analogic picture is observed for planar orientation with a corresponding shift of E(I) curves to higher current levels. For selected and gradually increasing levels of external magnetic field the difference in the vector B, parallel and perpendicular inclination with respect to tape plane on E(I), characteristics are presented. In this way the anisotropy manifestation at the different field levels is studied. The field vector remains perpendicular to tape axis. Also revealed is the influence of thermal cycling on E(I) through the thermomechanically induced cracking process.