# Stable, predictable and training-free operation of superconducting Bi-2212 Rutherford cable racetrack coils at the wire current density of 1000 A/mm2

Article · Tengming Shen, Ernesto S. Bosque, Daniel Davis, Jianyi Jiang, Marvis White, Kai Zhang, Hugh C. Higley, Marcos Turqueti, Yibing Huang, Hanping Miao, Ulf Peter Trociewitz, E. E. Hellstrom, Jeff A. Parrell, A. Hunt, S.A. Gourlay, Soren O Prestemon, D. C. Larbalestier

- Archive id: doi:10.1038/s41598-019-46629-3
- Published: 2019-07-15
- Venue: Scientific Reports
- DOI: https://doi.org/10.1038/s41598-019-46629-3
- PMID: 31308414
- Citations: 76
- Source URL: https://doi.org/10.1038/s41598-019-46629-3
- PDF: https://www.nature.com/articles/s41598-019-46629-3.pdf
- Provenance: openalex

## Abstract

Abstract High-temperature superconductors (HTS) could enable high-field magnets stronger than is possible with Nb-Ti and Nb 3 Sn, but two challenges have so far been the low engineering critical current density J E , especially in high-current cables, and the danger of quenches. Most HTS magnets made so far have been made out of REBCO coated conductor. Here we demonstrate stable, reliable and training-quench-free performance of Bi-2212 racetrack coils wound with a Rutherford cable fabricated from wires made with a new precursor powder. These round multifilamentary wires exhibited a record J E up to 950 A/mm 2 at 30 T at 4.2 K. These coils carried up to 8.6 kA while generating 3.5 T at 4.2 K at a J E of 1020 A/mm 2 . Different from the unpredictable training performance of Nb-Ti and Nb 3 Sn magnets, these Bi-2212 magnets showed no training quenches and entered the flux flow state in a stable manner before thermal runaway and quench occurred. Also different from Nb-Ti, Nb 3 Sn, and REBCO magnets for which localized thermal runaways occur at unpredictable locations, the quenches of Bi-2212 magnets consistently occurred in the high field regions over a long conductor length. These characteristics make quench detection simple, enabling safe protection, and suggest a new paradigm of constructing quench-predictable superconducting magnets from Bi-2212.

_Abstract reproduced under CC-BY (publisher license, via OpenAlex)._

Topics: [Applied Superconductivity & HTS Magnets](https://space-kitty.com/topics/applied-superconductivity)

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