Transport currents and magnetic properties of textured Bi(2223) tape

Abstract

Magnetic and transport properties of textured Bi(2223) tape with high critical transport current density (jc(77 K, 0 T)=2.8*104 A cm-2) were studied. Magnetic measurements show nongranular behaviour of shielding and transport currents for the magnetic field orientation perpendicular to the tape plane B perpendicular to p at low temperatures and low fields. At high magnetic fields and temperatures, however, quite large differences were observed, which depend on magnetic field sweep rate B and voltage criteria Ec. This is connected with granularity and inhomogeneity of the current flow. It was established that the magnetic field dependence of the critical current has a general scaling behaviour: jc(B, B, T)=jc(0, B, T) f(B/B0(B, T)) where the scaling function f becomes exp(-B/B0) for B/B0>or=1. The scaling parameter B0 is proportional to the irreversibility field Birr. Both B0 and Birr show an exponential temperature dependence.