Measurement of current density distribution in high T/sub c/ Ag-sheathed superconducting tapes

Flux history and local inhomogeneities in j/sub c/ govern the current distribution in measured Ag-sheathed TlBaCaCuO-2212 and Bi(Pb)SrCaCuO-2223 tapes. The sausage effect and local grain density and coupling fluctuations result in inhomogeneity in j/sub c/ distribution. This is reflected in violation of axial symmetry across the tape as well as longitudinal translation symmetry along the tape. Hall probe mapping of self field component with or without presence of external field was used to achieve the data for inverse calculation of current distribution and its dynamics in response to time variation of flux. To reveal the asymmetry in j/sub c/ distribution across the tape width the method of gradient field scanning/reversing was applied.