High critical current Ag and Ag alloy sheathed multifilament Bi-2223 tapes

Ag sheathed Bi-2223 multifilament tapes with filament numbers of 19, 37, 55 , and 85 were produced by the powder-in-tube method. Enhanced tape performa nce has been achieved by optimisation of the processing conditions. Key fac tors are addressed that include elimination of the 2212 phase, improving gr ain connectivity through reducing the 2201 phase and alkaline earth cuprate phases, increasing superconductor core density as well as enhancing curren t contribution from edge filaments. A high J(c) of 50 kA/cm(2) with an I-c of 42 A has been achieved reproducibly in 19 filament tapes with dimensions of 0.16x2.8 mm(2) and silver/superconductor ratios of 4.4:1. By reducing t he silver ratio, a J(e) of 14 kA/cm(2) with an I, of 38 A has been obtained in 55 filament tapes and an I-c of 84 A has been obtained in a tape with d imensions of 4x0.23 mm(2). A record J(c) of more than 30 kA/cm(2) with an I -c of 32 A was achieved in 250 metres long standard tapes. A 1250 m long pu re Ag sheathed tape and an 1100 m long Ag alloyed tape have been produced w ith a J(c) of higher than 25 kA/cm(2) by using optimised process parameters .