On August 12, Chinese researchers broke the record for the strongest steady magnetic field ever produced. At the Steady High Magnetic Field Facility (SHMFF) in Hefei, the team created a magnetic field of 45.22 Tesla. That's 780,000 stronger than the Earth’s magnetic field at 50 degrees North or South from the Equator.
The achievement beats the previous record of 45 Tesla, which was established by the National High Magnetic Field Laboratory (MagLab) in Florida in 1999. It was an incredible achievement and the length of time taken to surpass it, shows just how technically challenging it is to create these magnets. It’s no walk in the park.
The magnet at SHMFF, like the one at MagLab, is known as a hybrid magnet. The outside is a superconducting magnet. A superconductor is a material (usually at extremely low temperatures) through which electricity flows with no resistance. They can conduct larger electric currents, which in turn can produce a more intense magnetic field. There are limits though on just how strong one can go.
To balance this out and push further, there is a Bitter magnet in the inner portion. Also known as Bitter Solenoid, this type of electromagnet is built from metal plates and insulating spacers in a helical configuration. They can achieve extremely strong magnetic fields – the record at room temperature for the strongest continuous field is 37.5 Tesla, achieved in 2014 in the Netherlands. The drawback is that they require high-drive currents and dissipate a lot of heat. So a combined approach using the Bitter magnet design and a superconductor has been seen as a winning combination.
"To achieve higher magnetic field, we innovated the structure of the magnet, and developed new materials," Professor Kuang Guangli, the academic director of the High Magnetic Field Laboratory of Hefei Institutes of Physical Science, Chinese Academy of Sciences, where SHMFF is based, said in a statement. "The manufacturing process of the bitter discs was also optimized."
Studying these extreme magnetic fields is exciting in itself but also because it allows us to better understand magnetic technologies that have an impact in many fields.