Progress in superconducting performance of rolled multifilamentary Bi-2223 HTS composite conductors

Significant enhancements in critical current densities in rolled multifilamentary Bi-2223 HTS composite conductors have been achieved using the powder-in-tube technique. At 77 K and self field, oxide critical current densities (Jc)of 55 kA/cm2, overall or engineering critical current densities of 15 kA/cm2, and critical currents of 125 A have been achieved in different rolled multifilamentary composites. Progress in achieving such high electrical performance is believed to stem in part from an improvement of grain connectivity by reducing weak links. The Jc dependence on magnetic field and the degree of c-axis texture of these high quality conductors have been investigated at various temperatures. Our results also demonstrate that the critical current retention in magnetic field can be independently controlled from the self field critical current density, suggesting that flux pinning improvements and weak link reductions can be separately engineered into Bi-2223 composites fabricated using manufacturable processes