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Jan 28th 2019

Powerful Magnetic Energy Blows Up a Lab

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For the sake of science, researchers blew up a lab. It was mainly an accident.

In September 2018, physicists at the University of Tokyo were trying to create insanely strong magnetic energy in an indoor environment. They expected an explosion. But they didn’t know it would be so powerful that it would knock an iron door off its hinges.

Despite the damage, the experiment was a success. Through a method known as electromagnetic flux compression, the scientists managed to generate the longest-lasting and strongest controllable magnetic field in human history, according to AIP’s Review of Scientific Instruments. Such fields are key to discovering new solid-state physics, which could lead to advanced semiconductor chips for computers. The results could also advance research on alternative energy sources, such as fusion power.

Magnetic Energy Is Invisible but Powerful

We can’t see magnetic fields, but they’re all around us. They radiate from refrigerator magnets, credit card machines, speakers, microphones, electric motors, generators, MRI machines and transcranial magnetic stimulation. Even Earth and other Earth-like planets have magnetic fields, which deflect charged particles in outer space that could destroy the planet’s protective ozone layer, according to UC Berkeley. Stories of naturally magnetic stones date back to 23-79 AD in ancient Rome, and the Chinese developed the first maritime compasses about 4,500 years ago, said How Magnets Work. In 1925, British electrical engineer William Sturgeon invented the electromagnet. He coiled wires around a horseshoe-shaped piece of iron and then ran a current through the wires, noted ThoughtCo. Today, this technology is used in a variety of machines, including hard disk drives in computers, speakers, motors and generators.

Magnetic flux compression is a technique that uses massive amounts of energy to briefly squeeze a magnetic field, causing a spike in its strength, said Motherboard. Early demonstrations relied on TNT to generate the power needed to compress the magnetic field, but these experiments can only be conducted inside large bomb chambers or at facilities licensed as explosive-proving grounds, the Japanese scientists reported on AIP.

The University of Tokyo team took a different approach. They used more than 3 million amps of electric current, an amount of energy that makes a lightning bolt look like tiny spark. For comparison, lightning bolts have between 5,000 to 20,000 amps. The scientists injected the current into a machine that had been placed in an iron containment room. It was already producing magnetic energy roughly equivalent to the strength of the field created by an MRI machine. An electric current has its own magnetic field and, when it encountered the machine’s magnetic field, the two fields repelled each other. The force compressed the machine’s magnetic field, making it much more powerful than it was before, said AIP.

Scientists Got More Than They Bargained For

To understand just how powerful the explosion was, it’s helpful to know that scientists measure magnetic energy in units called Teslas (T) — named after Nikola Tesla, a Serbian-American scientist who helped developed modern-day electric power systems. Before the Japanese experiment began, the magnetic field in the machine measured 3.2 T. The researchers estimated that after they injected the current and the field compressed, it would intensify to 700 T. They got 1,200 T.

“‘With magnetic fields above 1,000 Teslas, you open up some interesting possibilities,'” the research team’s lead, Shojiro Takeyama, said in a press statement. “‘You can observe the motion of electrons outside the material environments they are normally within. So, we can study them in a whole new light and explore new kinds of electronic devices. This research could also be useful to those working on fusion power generation.'”

The intense magnetic energy lasted 100 microseconds, less time that it takes to blink your eye. But a similar process could create fusion power, Takeyama said in his statement. Fusion power is the ultimate in alternative energy sources. In the process, two light atomic nuclei combine to form a heavier nucleus. When they do, they release energy. The sun is a fusion generator. But replicating it is no easy task. One machine that shows promise uses a magnetic field to confine plasma, a cloud of charged particles, said IEEE Spectrum. “This requires a strong magnetic field in the order of thousands of Teslas for a duration of several microseconds. This is tantalizingly similar to what our device can produce,” said Takeyama.

Takeyama and his team are looking forward to their next experiment. They have begun to rebuild the iron containment room, including the door and adjusting the system to pump in more energy. Instead of 3 million amps, they plan to crank up the dial to 5 million amps. And instead of generating 1,200 T, they’re shooting for 1,500 T. If they blow up the lab again, they’ll likely call it a win.

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