Insulation and Heat Treatment of Bi-2212 Wires for Wind-and-React Coils

Higher Field Magnets, used in high energy physics (HEP) research, demand higher field materials such as Bi2212 round superconducting wire. The Bi2212 wire-manufacturing process depends on the coil-fabrication method and wire-insulation material. For example, the wind-and-react method requires the coil to be uniformly heated to the melt temperature and uniformly cooled to the solidification temperature. During the heat treatment cycle for tightly wound coils, the leakage melt from the conductor can chemically react with insulation on the conductor and creat short turns in the coils. In this project, conductor, insulation, and coils will be made to systemically study suitable insulation materials, coil fabrication methods, and heat treatment cycles. The high-temperature wire insulation and heat treatment cycle will be evaluated with wind-and-react coils. In Phase I, 800 meters of Bi2212 wire will be produced with three different insulations. Three small coils will be wound using each type of insulation. After heat treatment, the coils will be tested to select the conductor with the best insulation, and then four larger coils (2 inch diameter) will be wound using this conductor and reacted at various heat treatment cycles. The best insulation and heat treatment cycle will be used to fabricate a Bi2212 conductor strand for a Rutherford cable, which will be used to wind large racetrack coils for a HEP application in Phase II. Commercial Applications And Other Benefits as described by the Applicant: Better wire insulation, an improved coil winding technique, and an improved wire manufacturing process should find use in a wide range of high-field magnet applications including acclerators, fusion energy research, NMR spectroscopy, MRI, and other industrial magnets.