Scientists have broken the record for the strongest continuous magnetic field, according to a new research paper.
The National High Magnetic Field Laboratory, or MagLab, at Florida State University runs the world’s strongest continuous magnet for use by scientists, at 45 tesla—around 10 times stronger than a hospital MRI machine. Now, researchers at the lab have announced creating a 45.5-tesla magnet. It doesn’t seem like a huge jump, but it paves the way for even stronger magnets based on the principles of superconductivity.
Magnetism is a property of matter, typically generated by moving electric charges. Scientists create strong magnetic fields by creating coils (also called solenoids) of wire, generating a magnetic field that travels through the coil when charge passes through. Increasing the density of the current through the coil leads to a stronger magnetic field.
For two decades, 45 tesla was the strongest direct-current magnetic field that scientists could produce, meaning a magnetic field that doesn’t change its direction. That magnet is the centerpiece of MagLab and consists (among other components) of a “resistive magnet,” that is, a copper coil generating 33.6 tesla inside of a coil made of the superconductor Nb3Sn (niobium-3-tin.) The copper wire generates heat as current passes through, needs 31 megawatts of power to run—more than the peak power output of some nuclear submarines—and requires thousands of gallons of refrigerated water to cool.
Seungyong Hahn, associate professor at the FAMU-FSU College of Engineering and a MagLab scientist, led the team building the new magnet, which is about the size of a beer can. “Little Big Coil 3” features a superconducting magnet inside of a resistive magnet, and rather than using niobium-tin, it uses a tape coated with a kind of “cuprate” superconductor called rare-earth-barium-copper-oxide (REBCO) that achieves superconductivity at higher temperatures. The tape is only the width of a hair and can be wound tightly, increasing the density of the electrical current and therefore the magnetic field strength. The team also left off the insulation which would otherwise help direct the current, but could cause the superconductor to lose its superconducting properties, or quench. Leaving it off increases the density of the current and allows for safer quenching, according to the paper published in Nature.
Intense magnetic fields like these are generally most useful for basic science applications, such as trying to understand the properties of new materials. It’s important to note that this experiment is a proof-of-concept, meaning that scientists haven’t created a reliable tool to be implemented in experiments yet.
The real significance of this research is that it provides a base on which to build even more powerful magnets that use these copper-oxide superconductors, David Larbalestier, the MagLab chief materials scientist, told Gizmodo. For magnet scientists, there are now even stronger magnets on the horizon.