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Eric Hellstrom1 E. Bosque1 G. Bradford1 Michael Brown1 D. Davis1 C. English1 D. Hilton1 S. Hossain1 J. Jiang1 F. Kametani1 Y. Kim1 David Larbalestier1 J. Lu1 E. Miller1 G. Miller1 Y. Oz1 U. Trociewitz1

1, National High Magnetic Field Laboratory, Tallahassee, Florida, United States

Bi-2212 is the only cuprate superconductor that can be made as a round wire. It has high Jc and Hc2, can be fabricated with a variety of architectures, can be twisted and fully transposed as a Rutherford or a 6-on-1 cable, and can be lightly aspected to form a square or rectangular conductor. These characteristics are advantageous to design and build high-field magnets. Bi-2212 powder is now available from two sources, MetaMateria and nGimat, and short samples of wire made with nGimat powder have Jc = 9530 A/mm2 (4.2 K, 5 T) and Jc = 6860 A/mm2 (4.2 K, 15 T) with overpressure processing. Bruker-OST is fabricating > 1.4 km long Bi-2212 wire piece lengths with these powders. We have designed, modelled, wound, heat treated and tested coils that are Ic and stress/strain limited. There is good agreement between predictions from the models and the measured performance of the coils. This presentation will highlight the improvements in powders, wires, and heat treatments that underlie these advances in the performance of Bi-2212 wire.

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