High-J/sub c/ silver-sheathed Bi-based superconducting wires

Abstract

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.

Critical Current Limitations and Irradiation Effects in High-Temperature

“…They are characterized by extensive texturing and small-angle grain boundaries. In 50 cm long wires, jc ≈ 104 A/cm2 was achieved at 77 K, in the field of 10 kOe applied parallel to the wire [30]. In multifilamentary YBa2Cu3O x wires, 20 meters long, jc 4000-6000 A/cm2 was achieved at 50 K in zero magnetic field [31].…”

Next Generation Superconductors for High Field Applications

“…The tapes are then subjected to one or more pressing/heat treatment cycles. For Ag-sheathed TI (2223) tapes, Jc (77 K, 0 T) values of 1.4 x 10s A/m2 have been reported [3] while even higher values were found for Pb-stabilized Bi(2223) tapes (4.7 x 108A/m2 [4], 3.3 x 108 A/m2 [5]) ; values up to 4.0 x 108A/m2 have been achieved in our laboratory. It must be noted, however, that these high values of Jc have so far only been found for tapes less that 40 mm in length where pres sures as large as 50 kbar can be applied.…”

Superconductivity, High‐Temperature

“…Since HTSg materials are mechanically brittle and electrically anisotropic, the fabrication of HTSg wires or ribbons with large J c and great length is a formidable task. The powder-intube (PIT) method (Sato et al, 1991 yielded short BSCCO ribbons that display large J c ~ 10 5 A/cm 2 at 4.2 K, even at fields higher than 20 T. BSCCO ribbons of length of more than 1 km have been prepared by American Superconductor Corporation in the United States and Sumitomo in Japan with an overall J c of better than 8 X 10 3 A/cm 2 at 77 K. Very recently, American Superconductor Corporation made BSCCO multifilament wire over 1 km long with a/ c~ 14 X 10 3 A/ cm 2 at 77 K. The PIT method involves filling a metal tube with powder of the HTSg compound, drawing the filled tube to wire of smaller diameter, and rolling the wire to ribbon, followed by repeated compression and heat treatment (Fig. 11).…”