STACKED DOUBLE-PANCAKE COILS USING BI-2223 AG TAPES/

Silver-sheathed Bi-2223 long tapes are under development in the frame of a cooperation agreement among CISE, Europa Metalli and INFN. Multif ilamentary tapes with two different layouts (55 and 350 filaments) and superconducting powder composition (Bi1.8Pb0.34Sr2Ca2Cu3Ox and Bi1.7P b0.3Sr2Ca2Cu3Ox) were fabricated by the Oxide-Powder-in-Tube (OPIT) te chnique stal ting from hot extruded composite billets. The Bi-2223/Ag tapes were thermomechanically processed in unit lengths of 20 meters. The electrical characterizations of the tapes were performed on short samples, cut from the long units before the winding of the pancakes. T heir critical current I, dependence at 77 K and 4.2 K on magnetic fiel d, up to 0.5 T and 12 T respectively, was measured. Using these Bi-222 3/Ag tapes, four double pancakes were realized by the ''React & Wind'' (RW) method. Each single-pancake coil is made of 30 turns of tape (ab out 7.5 meters long) on a support having inner diameter of 70 mm. The degradation of the electrical properties after winding together with t he performances of the pancakes tested after the final assembling ape presented and discussed.