Silver-sheathed BiPbSrCaCuO wires were f a b r ic a t e d t h r o u g h t h e p o w d e r -i n -t u b e method. Jc-B p r o p e r t i e s , microstructures and Jc-strain properties wcre evaluated. Prototypes of coils and current leads were made and tested successfully.Critical current densities a t 77.3 K were 4 . 7~1 0~A/cm2 in a zero magnetic f i e l d , 3 . 1~1 0~ A/cm2 a t 0.1 'I'csla and 1 . 1~1 0~ A/cm2 a t 1 Tesla. In liquid He, 4.2 K, these wires can c a r r y 1 . 0 3~1 0~ A/cm2 a t 23 Tesla. J c and .Jc-B enhancements a r e due t o grain boundary improvements. Detailed investigation of Jc-B characteristics in magnetic fields, especially increasing and dccreasing f i e l d s , revealed t h a t h i s t o r y e f f e c t behaviors caused by weak l i n k s disappeared with improvements of grain boundary characteristics a t both temperatures. 1296 multifilamentary wires were shown t o sustain over 70 % of J c o even a f t e r a s t r a i n of up t o 0.GG % repeated 10 times. These r e s u l t s show f u t u r e possibilities of f l e x i b l e c a b l e s and r e a c t & windprocessed magnets. P r o t o t y p e s of c o i l s and c u r r e n t leads were fabricated using 20 m long wires. One c o i l showed critical currents of 54.2 A a t 77.3 K and 367 A a t 4.2 K. This coil generated B, of 142 Gauss a t 77.3 K and 87G Gauss a t 4.2 K. Critical c u r r e n t p r o p e r t i e s were investigated with back-up fields of up t o 990 Gauss a t 77.3 K and 3.7 Tesla a t 4.2 K. A prototype of react & wind-processed coil was demonstrated using o v e r 4 m I o 11 g mu 1 t i f i 1 am e n t a r y w i r e s , a n d s u c c e s s f u 1 l y produced enough magnetic f i e l d t o r o t a t e c o p p e r windings between s t e e l cores. 50 cm long c u r r e n t leads were made and t e s t e d a t 77.3 K and proved t o carry 242 A, showing overall current d e n s i t y of 2000 A/cm2 including silver-sheath.

The 4.2 K and 27 K current-carrying performance of a high-temperature superconducting (HTS) coil was measured in background fields up to 22.54 T generated by a hybrid magnet (Hybrid III) at the MIT Francis Bitter National Magnet Laboratory. The coil, 40 mm winding i.d., 108 mm winding o.d., and 113 mm high, consists of 17 double pancakes, each wound with silver-sheathed BSCCO-2223 tapes. Each pancake is the product of a react-and-wind method. In total, the test coil contains ∼1200 m of BSCCO-2223 conductor weighing ∼7 kg. Prior to the measurements in Hybrid III, the coil was tested in zero background field in the temperature range from 4.2 to 77 K. It was coupled to a Gifford–McMahon type cryocooler and at 15 K generated a peak field of 2.1 T; at 18 K, it generated 1.9 T, operating continuously for ∼50 h. In a 22.54 T background field of Hybrid III, the coil reached critical currents of 116.5 A ([Jc]sc, critical current density based on the BSCCO cross-sectional area only, of 261 A/mm) at 4.2 K and 67 A ([Jc]sc=150 A/mm) at 27 K, establishing record net fields at respective temperatures of 24.0 and 23.4 T for HTS magnets. These currents correspond to overall winding current densities of 47 and 27 A/mm. High-field critical current data for short samples of the tape of the same formulation at 4.2 and 27 K are also presented. Although a [J]sc of 261 A/mm at 24 T and 4.2 K for the test coil is significantly less than ∼600 A/mm for the short samples at the same operating point, if factors such as length, bending, and even differences in defining critical current are considered, the coil and short samples have nearly the same critical current performance. Electromagnetic stresses do not seem to have any negative effects on coil performance. Record fields of 24.0 and 23.4 T were achieved after the test coil had experienced, over a period of 15 months, 20 thermal cycles between room temperature and cryogenic temperatures.

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We prepared silver-sheathed BiPbSrCaCuO wires by the powder-in-tube method. Maximum critical current densities at 77.3 K were 5.4×104 A·cm-2 in a zero magnetic field, 4.2×104 A·cm-2 at 0.1 T and 1.2×104 A·cm-2 at 1 T. At 77.3 K, as the J c improves, the history effects decrease. J c and J c-B enhancements are due to the decrease and dispersion of nonsuperconducting phases, and to grain boundary improvements.

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