http://spectrum.ieee.org/sep08/6608
World's Most Powerful Magnet Under Construction
By Willie D. Jones
First Published September 2008
One hundred tesla without self-destructing
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. .
So far, researchers have reached 90 T, proving that the Magnet Lab is on the right track.
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.
Boebinger says the design and composition will allow researchers to get roughly 10 000 pulses out of the $8 million outsert magnet and about 100 pulses before a $20 000 insert magnet is destroyed.
“Simply put, pulse magnets are applied metal fatigue,” says Boebinger. “The trick is to hold off the breakdown of the bonds between the molecules due to mechanical and thermal stresses for as long as you can.”
Several ingredients in the secret sauce will let this magnet snap back where others have simply snapped. The magnet is made up of nine nested coils of wire. At the heart of the two innermost coils, where Lorentz forces create pressures 30 times as great as those at the bottom of the ocean, researchers have placed state-of-the-art nanoparticle wire composed of 82 percent copper and threaded through with silver strands no more than a few hundred atoms across. The copper-silver combination is stronger than either metal alone by a factor of 100.
From there, things get a little easier, if only on the wallet. “The further out you go, the lesser the forces are,” says Boebinger, “so you can afford to use material that is not as strong and not nearly as expensive.”