A hybrid magnet in China has just smashed the previous record for the most powerful stable magnetic field, scientists claim.
At the Chinese Academy of Sciences' Steady High Magnetic Field Facility (SHMFF), a magnet years in development achieved a steady magnetic field of 45.22 tesla – tens of thousands of times more powerful than your average souvenir fridge magnet.
This breaks the record for a steady magnetic field of 45 tesla, held by the National High Magnetic Field Laboratory (MagLab) in the US since 1999. The breakthrough sets new limits on conditions commonly used to study various physical phenomena, offering new opportunities in research and innovation.
Both the MagLab and SHMFF research teams have been working on their own hybrid magnets for some time. This is a magnet that uses two different ways of creating a magnetic field: an outer superconducting ring, and an inner resistive Bitter magnet (that's a magnet based on stacked plates). Each of these technologies have their own limitations: the superconducting magnet has low power input needs, but an upper limit on magnetic field strength; the Bitter magnet requires a much higher power input.
Combining the two technologies significantly mitigates these limitations, allowing for the propagation of a powerful, steady magnetic field. This is how MagLab developed its 45 tesla magnet, and how, in 2016, the SHMFF attained a steady magnetic field strength of 40 tesla – an incredible achievement in its own right.
But the Chinese Academy of Sciences' team was not content to leave it there, and have continued, since then, to work on their magnet. Finally, that hard work has paid off.
"To achieve [a] higher magnetic field, we innovated the structure of the magnet, and developed new materials," said physicist Guangli Kuang, the academic director of High Magnetic Field Laboratory of Hefei Institutes of Physical Science, Chinese Academy of Sciences. "The manufacturing process of the Bitter discs was also optimized."
With a power input of 26.9 megawatts, the team was able to achieve their 45.22 tesla record; and here, too, the magnet appears to be a leader. The 45 tesla magnet at MagLab requires a power input of 30 megawatts.
The SHMFF magnet, the team said, represents a step forward for materials science.
"The hybrid magnet of the National Steady State High Magnetic Field Experiment Facility produces the world's highest steady state magnetic field, which effectively improves the experimental conditions for scientists to carry out material science research, and will play an indispensable key role in the research of low-power electronic materials and other fields," the team wrote on the High Magnetic Field Laboratory website.
"As the strength of the magnetic field generated by the hybrid magnet increases, its openness and sharing level and user service level will also be greatly improved."
Meanwhile, MagLab retains the record for the most powerful magnetic field ever generated on Earth: in 2019, a superconducting magnet briefly achieved a strength of 45.5 tesla in a trial run. We'll be waiting to see if future improvements see it officially take the lead.