Fabrication and properties of Ag-clad Bi-2223 conductors and magnets.

摘要

Significant progress has been made in fabricating Ag-clad Bi-2223 tapes that are suitable for practical applications. Long lengths ((approx)100 m) of tapes with high transport critical current density (J(sub c)) were fabricated by the powder-in-tube technique, starting with partially reacted precursor powders. The tapes were given appropriate heat treatment, and growth of the 2223 phase at each step of the heat treatment was studied. At 77 K, J(sub c) values of >4 x 10(sup 4) A/cm(sup 2) and (approx)1.5 x 10(sup 4) A/cm(sup 2) have been achieved in short-length and (approx)70-m-long tapes, respectively. Compact and robust pancake coils were fabricated from the tapes by the wind-and-react method. Pancake coils were stacked in series to make magnets. The coils and magnets were characterized as a function of applied magnetic fields at various temperatures. A magnet containing 10 pancake coils ((approx)480 m of conductor) generated magnetic fields as high as 2.6, 1.8, 0.53, and 0.36 T at 4.2, 27, 64, and 77 K, respectively. Progress in the manufacturing of long lengths of Bi-2223 conductors and their performance are presented.