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World's Strongest Magnetic Field Is Demonstrated
lazarus_ writes "PORTLAND, Ore. -- Researchers at Florida State University's National High Magnetic Field Laboratory in Tallahassee achieved the holy grail of magnetism recently when their high-temperature superconductor attained the coveted 25-Tesla field strength record."
Metalheads from as far south as Miami, as far north as Atlanta, and as far west as Memphis were seen hurtling through the air at breakneck speed headed toward the city of Tallahassee.
Tampa, known for it's unusually dense Death Metal population, was particularly hard hit.
Heil Sig! -Rob
I worked at a place about 17 years ago that was using a superconducting magnet (3-5 T) and the "owners manual" expressly forbade attaching an ohmmeter to the magnet coil to see if the coil had become cold enough to superconduct. The problem was that at even low milliampere currents, the coil could store about as much energy as a photographic flash capacitor. Disconnecting the ohmmeter could create a nasty zap and possibly create a damaging arc inside the coil.
The field was quite fun if you didn't care about your credit cards. You could feel the eddy current drag on a penny if you moved it in the field and copper rings would fall in slow motion.
Ah! The good old days!
Two wrongs don't make a right, but three lefts do.
Magnetic flux is magnetic flux density multiplied (or integrated) by the surface. The unit of magnetic flux is Weber. That's where Earth wins over all man-made magnets.
No, this is the largest magnetic field ever created (that we know about), although it does cover a fairly small area. The Earth's magnetic field is weak but very, very large; magnetic fields drop off rapidly (Inverse cube of distance, if I recall correctly) as you move away from the source. Similarly, speaker magnets are fairly weak (on the order of a few hundred to a thousand gauss) but since they are large, they affect a greater area than a small rare-earth magnet that has a 1 Tesla (10,000 Gauss) field strength - a few meters away, the magnetic field is lost in the "background noise" of the Earth's magnetic field. While this is almost certainly smaller than a tiny rare-earth magnet, it still won't cause compass needles all over the Earth to point in funny directions; just those around the building it's installed in. In summary: powerful magnet != big field.
That's it. I'm no longer part of Team Sanity.
Creating a 25 tesla magnetic field is not a big deal in itself. People have been using ~ 40 tesla, pulsed magnetic fields to study superconductors for years. There are also techniques to generate 1000 tesla fields (first reference i googled: http://www.intas.be/catalog/94-3569.htm). They last about a millisecond. How? Well basically, by using explosives. While i only skimmed this article, the peice they are probably leaving out is that they are creating 25 tesla magnetic fields over a large area or for a significant amount of time (more than a second or two). This is really useful and takes tons of energy, so it's an achievement worth mentioning. What i don't understand is why the existence of those other magnets is overlooked, especially since the National High Magnetic Field Laboratory collaborates with lots of people who use them.
But higher transient fields have been produced for some time:
Large Z-Pinches routinely reach 100T, and may, at stagnation, quite conceivably reach fields as high as 10^4 T
In laser produced plasmas, magnetic fields have actually been measured to rise up to more than 3*10^4 T
Tatarakis et. al. Phys. of Plas. 9/5 pp. 2244 (2002)
Working for necessity's mother.
The article, in addition to being a dupe , also calls the director of the NHMFL "Jeff Crow". Last time I talked to him, his name was Jack.
Still, at 25 Tesla you wouldn't want to get too close. If your screw isn't completely pure, and nothing ever is, the impurities may lead to little bits of it being magnetically affected. That can lead to deformation and such. It's not that you're entirely safe around magnet that big, it's that the screw isn't going to tear out of your bone at splintering speeds, "severely injuring" you.