Mechanisms of Current Transport in Silver Sheathed Bi-2223 Tapes

Abstract

Silver sheathed Bi-2223 tapes have been investigated by transport and magnetization measurements. The critical transport current, which is limited by flux creep at high temperatures and by weak links at low temperatures, is interpreted in the framework of the ‘brick wall’ model assuming a small fraction of long grains near the silver sheath and a large fraction of short grains inside the tape. The magnetization results show flux creep behaviour in the whole temperature range and are lower than the critical transport current in the flux creep region by an almost field independent factor that increases with decreasing temperature. This can be explained by a reduction of the geometrical length scale of current loops.