Fabrication and characterisation of superconducting Bi-2223/Ag tapes with high critical current densities in km lengths

Long length Bi-2223/Ag tapes with high critical current densities are needed for large-scale applications. In this paper, recent results from NST are being presented, describing recent results reaching critical current densities of 23 kA/cm/sup 2/ and engineering critical current densities of 5.2 kA/cm/sup 2/ at 77 K over the whole length of a 1250 metre long Bi-2223/Ag tape. To our knowledge this is the highest critical current density reported for Bi-2223/Ag tapes longer than 1 km. The approach for improving the homogeneity and the considerations of processing and handling the long length tape are presented. Various Ag alloy sheathed Bi-2223 tapes have been made by our standard production line. The properties of these tapes are compared.