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Scientists build world's most powerful magnet

Using the strongest materials known to man, scientists are building the most powerful electromagnet in the world — one that won't blow up a split second after it's turned on.
Image: Electromagnet
A new electromagnet being built at Florida's National High Magnetic Field Laboratory will be the world's first reusable 100 tesla magnet. Its pull will be about two million times stronger than the average refrigerator magnet.
/ Source: Discovery Channel

Using the strongest materials known to man, scientists are building the most powerful electromagnet in the world — one that won't blow up a split second after it's turned on.

The entire magnet will be a combination of coil sets weighing nearly 18,000 pounds and powered by jolts from a massive 1,200-megajoules motor generator. Once activated, the new magnet should be about two million times more powerful than the average refrigerator magnet.

"The new magnet at the High Field Lab is a fantastic leap forwards in terms of our capability as a scientific community to explore materials under extreme conditions," said Ian Fisher, a scientist at Stanford University.

"In several cases one needs to go to these sorts of extremes to fundamentally understand materials" used in high-temperature superconductors and other applications, said Fisher.

The electromagnet consists of two parts. The outer section, or outsert, will be a cylinder, 1.5 meters (4.9 feet) in diameter and 1.5 meters tall, and solid except for a small hole, less than 8 inches wide, bored through the middle.

Inside that hole rests the insert, nine coils made of copper and strengthened with silver wire as thin as 100 atoms across. Together, the copper and silver create the strongest material known to man, according to Greg Boebinger, director of the National High Magnetic Field Laboratory in Florida. The magnet is being built at the Los Alamos National Laboratory.

The pressures generated inside the insert will be equivalent to 200 sticks of dynamite going off together, or about 30 times the pressure at the bottom of the ocean.

Very few things can survive those kinds of forces for long — including the new magnet.

The scientists expect each $20,000 insert to survive about 100 pulses. The $8 million outsert should last about 10,000 pulses. Each time the magnet pulses it bends the copper and silver wires, creating tiny cracks in the metal. The cracks in the copper run into the silver wires, which stops the cracks from spreading.

"It's like reinforced concrete," said Boebinger.

The copper acts like like the concrete, strong and tough. The silver acts like the steel rebars running through the concrete, providing flexibility.

Together the inner and outer magnets can already create 90 teslas.

Teslas measure the pull of a magnetic field. Even one tesla is quite powerful. The Earth's magnetic field is about 50 microteslas. An average MRI (magnetic resonance imaging) machine ranges from 0.5 to 1.5 teslas.

The scientists hope that within months they can develop the new electromagnet to reach their target goal of 100 teslas.

This won't be the first 100-tesla electromagnet. Technically it won't even be the world's most powerful magnet. Electromagnets as strong as 1,000 teslas have been created before. The new electromagnet will be the world's first reusable 100-tesla magnet.

All other magnets of this power were one-and-done. The powerful forces the other electromagnets created tore themselves, and usually the samples being studied, apart milliseconds after they were turned on. Those magnets have their uses, says Boebinger, but destroying samples can be a problem and building new magnets can be expensive.

Studying the same material over and over without destroying it could help scientists tease out the properties of superconductors and other novel materials, said Boebinger, who points out that previous magnet work at the lab helped produce neodymium magnets that enabled wireless phones, cordless drills, and other handheld electronic devices.

New materials, like iron oxyarsenide, could eventually lead to high definition MRI scans or power lines that don't lose any energy to heat and would save consumers millions of dollars each year.

Eventually, however, even this electromagnet will break under the incredible pressures, and when it does it will be loud.

"They have to evacuate the entire building when they turn the magnet on," said Boebinger. "A magnetic disassembly will make a big boom."

An earlier version of this report misstated the location of the magnet construction site and incorrectly referred to Florida power requirements.