National MagLab creates world-record magnetic field with small, compact coil

https://news.fsu.edu/news/science-technology/2019/06/12/national-maglab-creates-world-record-magnetic-field-with-small-compact-coil/

A novel magnet half the size of a cardboard toilet tissue roll usurped the title of “world’s strongest magnetic field” from the metal titan that had held it for two decades at the Florida State University-headquartered National High Magnetic Field Laboratory.

And, its makers say, we ain’t seen nothing yet: By packing an exceptionally high-field magnet into a coil you could pack in a purse, MagLab scientists and engineers have shown a way to build and use electromagnets that are stronger, smaller and more versatile than ever before.

Their work is outlined in an article published today in the journal Nature.

“We are really opening a new door,” said MagLab engineer Seungyong Hahn, the mastermind behind the new magnet and an associate professor at the FAMU-FSU College of Engineering. “This technology has a very good potential to entirely change the horizons of high-field applications because of its compact nature.”

This new magnet is a plucky David to the MagLab’s conventional Goliaths, said National MagLab Director Greg Boebinger.

“This is indeed a miniaturization milestone that could potentially do for magnets what silicon has done for electronics,” he said. “This creative technology could lead to small magnets that do big jobs in places like particle detectors, nuclear fusion reactors and diagnostic tools in medicine.”

The 45-T, as it is called, is still the world’s strongest working magnet, enabling cutting-edge physics research into materials. But in a test, the half-pint-sized magnet invented by Hahn, tipping the scales at 390 grams (0.86 pounds), briefly surpassed the reigning champ’s field by half a tesla, a compelling proof of concept.

How could something so small create a field that big? By using a promising, new conductor and a novel magnet design.

Both the 45-T magnet and the 45.5-T test magnet are built in part with superconductors, a class of conductors boasting special properties, including the ability to carry electricity with perfect efficiency.

The superconductors used in the 45-T are niobium-based alloys, which have been around for decades. But in the 45.5-T proof-of-principle magnet, Hahn’s team used a newer compound called REBCO (rare earth barium copper oxide) with many advantages over conventional superconductors.

Notably, REBCO can carry more than twice as much current as a same-sized section of niobium-based superconductor. This current density is crucial: After all, the electricity running through an electromagnet generates its field, so the more you can cram in, the stronger the field.

Also critical was the specific REBCO product used — paper-thin, tape-shaped wires manufactured by SuperPower Inc.