100 Tesla magnet being constructed, biggest reusable magnet in the world

Tallahassee (FL) - Researchers working at the National High Magnetic Field Laboratory (MHMFL) in Florida are putting the final touches on what will be the largest reusable magnet ever constructed. It's a nearly six foot diameter outer case with an 8" center core. Capable of producing magnetic fields roughly 100 times more powerful than an MRI or two million times more powerful than a refrigerator magnet, each $20,000 core will withstand around 100 1200-megajoule pulses, with the $8 million outter case withstanding around 10,000. Previous "big magnet" research efforts like this have lead to the creation of neodymium magnets which enable our cell phones and cordless hand tools.

The world's most powerful magnets ever constructed have been approximately 2x to 10x more powerful than this magnet. However, those were called "one use magnets" as they destroyed themselves while in use. In fact, this magnet will also destroy itself during testing, although it's being designed to withstand as many tests (pulses) as possible. The pressures exerted on a 90-100 Tesla field strength magnet are enormous, roughly 30x greater than those experienced at the bottom of the ocean, or the equivalent of 200 sticks of dynamite going off simultaneously.

The wires used in the center core are comprised of copper and silver, a chemical mix design to act like concrete. While the copper is very strong it cracks easily, just like concrete. The silver acts as reinforcement to keep the copper intact for a longer time, but even with the reinforcing, it's only a matter of time until the magnet core explodes. In fact, the explosion will be so massive that the whole buidling has to be evacuated when the magnet is in use to protect nearby researchers from teh expected deafening sound.

The magnet's reusable design consists of two parts, an outer section, or outsert cylinder, that is nearly six feet wide and five feet tall, and an 8" diameter insert comprised of nine separate coils. Together, they weigh nearly 18,000 lbs. The wires used within the coils are as small as 100 atoms in diameter. The entire device will be supercooled to "high-temperature superconductor" levels when in use, drawing 7% of Tallahassee's available power supply.

It is believed the research will ultimately enable the creation of some unexpected products, such as high-tension power lines that do not generate heat using materials achieving high-temperature superconductivity, as well as more obvious products like higher definition MRI scans and better cellphones.

In truth, the concept of having a reusable magnet of this strength is very exciting to the researchers. The ability to have a controlled, scientific approach to reproducible experiments in this field at these levels is unprecedented.


Notes

One Tesla is a very large gauge of magnetic strength, named after physicist Nikola Tesla . A typical MRI would only use around 1 Tesla. The Earth's magnetic field is about 0.00005 Teslas (though it is slowly decreasing over time for reasons not yet known). Another perhaps more well known gauge of magnetic strength is Gauss, named after the German mathematician Karl Friedrich Gauss (1777–1855). The 100 Tesla magnet would represent about 1,000,000 Gauss. Typical handheld bar magnets are about 100 Gauss. Cordless drills are around 25 Gauss. Very strong laboratory magnets are 100,000 Gauss. And just to show that mankind does not outdo nature, the surfaces of Neutron stars are believed to be 100 million Teslas.

The MHMFL builds on a history of previous high density magnets. In 1994, for example, the operation of a 27 Tesla magnet was first achieved on their site. It was built atop a DC facility with a 1 meter thick concrete base. After that, the lab achieved additional records over time of 30, 33, 35, then hybrid magnets of 45 and pulsed magnets of 60 for long-pulse; 77.8 tesla short pulse and ultimately the 85 Tesla multi-shot magnet. Construction of this magnet is not yet completed, though it is currently in operation at around 90 Teslas.