Recent Improvements in Long Length Bi-2212 Conductors
Bi-2212 multifilamentary Powder In Tube (PIT) tapes were fabricated in lengths of a few hundred meters. Improvements in long length tapes were made by optimizing thermomechanical processing to minimize bubbles. Critical current density in tapes up to 75 meters in length was evaluated by measuring critical current in sections and end to end. Jc greater than 200,000 A/cm2 in zero field and greater than 120,000 A/cm2 in 5 tesla at 4.2 K were obtained reproducibly in short samples. Jc greater than 100,000 A/cm2 in zero field, at 4.2 K was measured end to end in 50 meters of pure Ag sheathed multifilamentary PIT tape. Jc of 60,000 A/cm2 in zero field, at 4.2 K was measured end to end in 75 meters of Ag alloy sheathed multifilamentary PIT tape. A coil made from this conductor with react and wind techniques was tested at 4.2 K. Key factors to scale up from short sample to long length heat treatment are discussed.
KeywordsCritical Current Density Short Sample Zero Field Pure Silver Isothermal Heat Treatment
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