Breakthrough in Miniature Superconducting Magnets

Researchers at ETH Zürich have developed the most powerful miniature superconducting magnets to date, capable of generating magnetic fields exceeding 40 tesla. This innovation represents a significant shift from traditional high-field science, which typically relies on large, power-intensive machines. The newly designed magnets, which can fit in the palm of a hand, operate on less than one watt of power, making high-field research more accessible.

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The research team constructed two compact all-high-temperature superconducting (HTS) magnets using rare-earth barium copper oxide (REBCO) tape. One magnet achieved a magnetic field strength of 38 tesla with two pancake-shaped coils, while the other, featuring four stacked coils, reached 42.3 tesla. For context, a standard hospital MRI machine operates at 1.5 to 3 tesla, and the previous record for an all-HTS magnet was 26 tesla. In comparison, the world-record steady-state magnet at the U.S. National High Magnetic Field Laboratory operates at 45.5 tesla but consumes over 20 megawatts of power and requires extensive infrastructure.

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The development of these miniature magnets involved overcoming significant engineering challenges. The primary hurdle was winding REBCO tape around a bore measuring just 3.1 millimeters in diameter, a size that standard methods cannot accommodate without damaging the superconducting layer. The researchers devised a novel technique that relocates the connection point between coils to the bore's exterior, preserving the integrity of the tape during the winding process. Additionally, they employed a no-insulation winding method and soldering across the entire coil, resulting in current densities of up to 2,257 amps per square millimeter, surpassing most large superconducting systems.

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The implications of this breakthrough are substantial. Currently, accessing magnetic fields above 28 tesla requires time at national laboratories, which can be prohibitively expensive for many university labs and research hospitals. The introduction of a compact, cost-effective magnet capable of operating in this range could democratize high-field nuclear magnetic resonance (NMR) spectroscopy, enhancing research capabilities in molecular structure studies. The researchers also highlighted potential applications in quantum materials research and next-generation micro-NMR technologies.

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Despite the promising results, the team acknowledges challenges related to field homogeneity, which affects the uniformity of the magnetic field across the bore. They plan to address this issue in future work, with aspirations to achieve direct NMR measurements exceeding 40 tesla. A patent application for this innovative technology is already underway, indicating a commitment to further development.

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• “For now, the demonstration stands as proof that extreme magnetic field science doesn’t have to stay locked inside a national laboratory.” — ETH Zürich Research Team

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This advancement in superconducting magnet technology not only showcases the potential for more accessible high-field research but also paves the way for future innovations in various scientific fields.

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