The effect of weak links on the critical current in (Bi,Pb)2Sr2Ca2Cu3O10 silver sheathed tapes

Abstract

Silver sheathed Bi-2223 tapes with critical current densites of about 15 kA/cm2 (77 K, B=0) have been investigated by transport and magnetization measurements. The superconducting current through the tape can be explained by assuming a network of platelike grains coupled by weak links. At high temperatures the critical current is governed by flux creep of pancake vortices within the grains. At temperatures below 40 K the critical current is found to be limited by weak links. This model explains the temperature and field dependence of the critical transport current. Differences between the critical transport and magnetization current observed at medium and low temperatures can be explained by a reduction of the geometrical length scale of current loops.