Fabrication and properties of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub y/ multilayer superconducting tapes and coils

A flexible 100 m-class Bi-2212 multilayer superconducting tape was fabricated by the continuous heat treatment technique using a Ag-0.2 at% Mg sheath. The sheath material did not change the J/sub c/ value of the multilayer superconducting tape and doubled the tensile stress tolerance compared with pure Ag sheathed Bi-2212 tape. The J/sub c/ value of the Ag-0.2 at% Mg alloy sheathed tape was above 10/sup 5/ A/cm/sup 2/ at 4.2 K, 21 T and 1.3/spl times/10/sup 5/ A/cm/sup 2/ at 20 K, 0 T. A stacked pancake coil fabricated by the "react & wind" technique carried 120 A at 10 K and 90 A at 20 K. The coil could be operated for 24 hours under 18 K with operating current of 75 A.