MAGNETIC MOMENT: Engineers are readying a supercooled, record-setting 100-tesla magnet at Los Alamos National Laboratory. The magnet will have to withstand forces equivalent to 200 sticks of dynamite.
Multiply the magnetic field strength of a refrigerator magnet by 2 million and you'll be in the ballpark of the strength of the magnet that researchers at the National High Magnetic Field Laboratory, based near Florida State University in Tallahassee, are trying to create. When completed later this year, the pulsed electromagnet, located at the lab's facility at the Los Alamos National Laboratory, in New Mexico, will reach 100 tesla, the holy grail of magnetic field strength. And in another first, if all goes according to plan it will reach that level—about 67 times as high as a typical MRI—without blowing itself to smithereens.
Why would anyone need a magnet that strong? Greg Boebinger, director of the Magnet Lab, says that this magnetic field strength is the only way to test the properties of newly discovered high-temperature superconductors like iron oxyarsenide, which may improve the performance of MRI machines and high-voltage power lines while lowering their cost. A 100‑T magnet would also let you conduct certain zero-gravity experiments without traveling into space and let you develop magnetic propulsion systems that could eventually replace those that burn rocket fuel.
So far, researchers have reached 90 T, proving that the Magnet Lab is on the right track. “We've been running it at the hairy edge,” Boebinger says, referring to the tradeoffs he and his colleagues must make to get the most out of the magnet without destroying it in the process. Researchers have been able to generate magnetic fields stronger than 100 T for years but knew that any such experiment was a one-and-done situation, because these magnets would almost instantly be torn apart by their own forces.
Boebinger says the Magnet Lab is close to reaching the material tensile strength needed to repeatedly break the 100-T barrier. That is no small feat, considering that the US $10 million magnet will have to resist enormous Lorentz forces—the electromagnetic push on electrons that attempts to force them in a direction perpendicular to the flow of current. In a magnet that strong, says Boebinger, these forces are “equivalent to the explosive force of 200 sticks of dynamite packed into a volume of space the size of a marble.”
more:
http://spectrum.ieee.org/sep08/6608