Transverse distribution of the transport current density in (Bi, Pb) 2223 tapes

Abstract

The distribution of the critical transport current density, J c, has been measured across the core thickness of silver sheathed (Bi, Pb)2223 tapes which contained silver addition of different particle sizes. We have found the J c of tapes without silver addition and with 8 wt% silver addition of small particle size decreases continuously with distance from the core-sheath interface. The J c of layers close to the silver sheath is up to four times higher than that of central layers, e.g. 3 × 10 4A cm −2 near the sheath and 7 × 10 3 Acm −2 in the centre at 77 K and self field. The tape with addition of 50 wt% 80 μm silver particles shows a uniform J c of about 2 × 10 4 A cm −2 throughout the core thickness. The V− I characteristics of the baser core of the tape without silver addition have also been measured in magnetic fields.