Transport and magnetization currents in BSCCO/Ag tapes

A (Bi,Pb)SrCaCuO-2223/Ag tape has been produced by thermomechanical processing. Transport critical current densities, J/sub c/'s, have been measured between H=0 and 7 T and T=7 to 75 K. Magnetization currents have been determined for similar temperatures and fields (0 to 5 T) oriented parallel and orthogonal to the thickness of the tape. Dimensional scaling arguments show that flux penetrates most quickly along the tape thickness direction (for fields parallel to the tape plane and therefore the ab planes of the textured BSCCO grains). This implies that the anisotropy ratio of J/sub c/ and J/sub ab/ is reduced in tapes as compared with single crystals, which is consistent with predictions of the brick wall model. The H dependence of the magnetization currents and effective pinning potentials were also measured for similar field orientations. Fast magnetic relaxation causes an exponential field dependence of transport and magnetization currents. Temperature dependences for H/sub 0/ for transport and magnetization measurements are interpreted in terms of different time scales (or voltage criteria).<
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