World's Strongest Magnet!

A 45-tesla hybrid magnet—nearly a million times Earth’s magnetic field—has become a real-world laboratory tool for probing matter, generating electricity, and even levitating objects that aren’t normally magnetic. The National High Magnetic Field Laboratory in Tallahassee, Florida, has maintained a Guinness World Record for the strongest continuous magnetic field since 2000, and the magnet’s extreme strength comes with practical consequences: filming inside or near it is notoriously difficult because the field can interfere with electronics and even damage camera equipment.

The magnet’s peak field isn’t spread evenly across the apparatus. It reaches its maximum in a narrow, centimeter-tall region at the center of a bore running through the middle, while the field drops off rapidly outside that core. Still, the surrounding “fringe field” remains dangerous. A key safety threshold is the 100 gauss line: objects with the right shapes can start pivoting and then accelerate toward the magnet before anyone can react. The lab therefore treats ferromagnetic items—like metal implants—as off-limits within that zone.

Engineering the record requires more than superconductors alone. Superconducting wire can only sustain magnetic fields up to roughly 20 tesla before it stops being superconducting. To push higher, the system combines an outer superconducting magnet with an inner resistive magnet. The superconducting outsert produces 11.5 tesla, while the resistive inner magnet adds 33.5 tesla; field addition yields the 45-tesla peak. Ramping to full power takes about an hour and a half because the resistive section demands enormous current—47,000 amps—along with substantial cooling. The resistive coils are built from stacked, thin conductor plates (a Bitter-style design) so cooling water can be driven through the structure and remove heat from the innermost windings.

Once running, the magnet turns basic physics into visible effects. Ferromagnetic materials are pulled in, but the more surprising demonstrations involve non-ferromagnetic matter. A Nerf football stuffed with steel washers becomes easy to identify because the washers dominate the response. Ferrofluid—tiny magnetite particles suspended in liquid—forms ridges and spikes as particles align with the field, and it can climb the container walls. Conductive metals also behave differently when moving: as a metal plate falls through the field, changing magnetic flux induces eddy currents that generate their own magnetic field to oppose the motion, slowing the plate via Lenz’s Law. The induced currents dissipate energy as heat, and the lab notes that in some setups the heating can be intense enough to boil water.

The magnet also enables levitation in multiple ways. With superconductors below their critical temperature, induced currents can persist and expel magnetic flux, allowing stable “human levitator” demonstrations above a ring of superconductors. Separately, diamagnetism and paramagnetism let strong fields repel or attract materials like water and liquid oxygen, enabling levitation of items that aren’t ferromagnetic—though the lab uses a weaker 31-tesla system for optical viewing.

Beyond spectacle, the lab’s goal is material discovery. Extreme magnetic fields help researchers test how electrons scatter in ultra-clean materials and how matter behaves under harsh conditions—alongside high electric fields, high pressure, and ultra-low temperatures. The record magnet’s power draw is significant—about 8% of the lab’s local generating capacity, costing roughly $250,000 to $300,000 per month—but the payoff is a new experimental frontier that scientists expect to reshape research over the next decades.