Generation of 24.0 T at 4.2 K and 23.4 T at 27 K with a high-temperature superconductor coil in a 22.54 T background field
- Osaka Research Laboratories, Sumitomo Electric Industries, Ltd., Osaka 554 (Japan)
- Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
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 {similar_to}1200 m of BSCCO-2223 conductor weighing {similar_to}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 {similar_to}50 h. In a 22.54 T background field of Hybrid III, the coil reached critical currents of 116.5 A ([{ital J}{sub {ital c}}]{sub {ital sc}}, critical current density based on the BSCCO cross-sectional area only, of 261 A/mm) at 4.2 K and 67 A ([{ital J}{sub {ital c}}]{sub {ital 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 [{ital J}]{sub {ital sc}} of 261 A/mm at 24 T and 4.2 K for the test coil is significantly less than {similar_to}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. (Abstract Truncated)
- OSTI ID:
- 253337
- Journal Information:
- Applied Physics Letters, Vol. 67, Issue 13; Other Information: PBD: 25 Sep 1995
- Country of Publication:
- United States
- Language:
- English
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