RECENT ISSUES IN FABRICATION OF HIGH-TC MAGNETS AND LONG-LENGTH MULTIFILAMENT CONDUCTORS

After fabricating long lengths (30-100 m) of Ag-clad Bi-2223 tapes by the powder-in-tube process, we co-wound them into pancake-shaped coils by the ''wind-and-react'' approach. Test magnets were then fabricated by stacking and connecting the coils in series. We then characterized the magnets at the temperatures of liquid helium (4.2 K), liquid neon (27 K), pumped liquid nitrogen (64 K), and liquid nitrogen (77 K) and in background fields of up to 12 T. A test magnet containing 10 panca ke coils generated magnetic fields as high as 2.6 T at 4.2 K. Multifil ament conductors of BSCCO-2212 and BSCCO-2223 have also been fabricate d in this study. A BSCCO-2212 multifilament conductor was fabricated w ith both pure silver and dispersion-strengthened silver (Ag-Al2O3) as the sheath materials. After final heat treatment, the yield strength o f the Ag-Al2O3 Matrix was twice that of the pure Ag matrix. At 4.2 K, critical current density of the Ag-Al2O3 multifilament conductor appro ached 5 x 10(4) A/cm2 at zero applied field and >2 x 10(4) A/cm2 at 12 T. This paper addresses certain issues concerning high-T(c) magnets a nd long-length multifilament conductors.