Where's my bloody pen? I'm sure I put it down here somewhere...
They call it their own “moon shot”, but there isn’t – unfortunately – any “oh wow” visual when you fire a 100-plus Tesla magnet: just a powerful new instrument to use in physics and materials science. At the end of last week, the Los Alamos National Laboratory held its breath and pressed “ok” to see if its planned magnet run, …
I don't think we take MRI for granted. Those are very expensive machines. Lots and lots of people have done fundraising things for ages and ages to buy one for their favourite large hospital.
United Kingdom guideline price list for a go in one:
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3T isn't at all out of the ordinary for clinical MRI these days (my department got one last year). There are MRI machines used in research with human subjects up to 9.4T in regular operation, although a recent paper suggested that going beyond 14T isn't likely to be practical.
I believe the (very valid) point was that "well over triple" is not a good description of the ratio of this thing and your run-of-the-mill MRI device when a typical (rather modern) clinical device is indeed more like 3T. You would probably have a hard time fitting an adult human being inside your 9.4T research device. Nothing to do with whether it's OK to subject humans to such fields, everything to do with the difficulty of building one that can actually take something larger than a finger inside.
No. I've seen 7T for humans and know people who worked with it regularly in Western Ontario (it is now being replaced). There are 9.4T systems scanning humans (their brains, not just their fingers) in Chicago, Minnesota, Julich, and Tubingen. If you want a reference read Duyn, J.H., The future of ultra-high field MRI and fMRI for study of the human brain, NeuroImage (2011), doi:10.1016/j.neuroimage.2011.10.065. You can, of course also get small-bore systems for imaging hands and hand-sized things at 7T and 9T - maybe these are what you are familiar with?
I agree entirely that the ratio between the fields in the interesting thing and human imaging systems is well out - I was just pointing out that there are plenty of 3T run of the mill turnkey systems from Siemens and the like out there.
“A 2.4 megajoule capacitor bank is used to energize the smaller magnet, inside a much larger magnet, to distribute these huge forces across a very massive magnet system”
This single sentence remind me of something else...
"It's a secret lab where they take the brains out of zombies and put them in the heads of other zombies to create a race of super-zombies."
Fond memories of working for a stint at the High magnetic field lab in Grenoble during PHD.
Once I forgot to chain the 200l Nitrogen vessel to the wall... and when I ramped up the field to 30T (all alone in a huge lab, in the middle of the night when the leccy is cheaper) the thing started moving on its coasters and crashed into the apparatus, while my back was turned studying the instrument rack. Fright of my life, but thankfully nothing broke so my supervisors never heard about it...
If I've got my sums right
Energy density of a 100T field in a vacuum = 4 x 10^3 MJ/m^3 (air pretty much the same)
For comparison, energy density of gasoline = 34 x 10^3 MJ/m^3, less than 9x higher
Energy density of a magnet field goes as the field strength squared. This may give some insight into the self-destructive tendency!
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