World record for strongest steady magnetic field 'broken' by Chinese team Chinese scientists claim to have broken the record for producing the strongest steady magnetic field, one that's at least a million times more powerful than planet Earth's, using a superconducting system. The hybrid magnet was described as being made out of a resistive insert within coils of superconducting material. The …
In cases like this, how do you verify the accuracy of measurements when you're measuring beyond the realms of what's been measured before? How can you prove that your measuring equipment is properly calibrated?
Or is the peak measurement merely inferred from what can verifiably be measured accurately?
You measure against phenomenon (such as the Hall Effect, Quantum Hall Effect, or even optically using the Zeeman Effect) that rely on what Physicists call "first principles" if you can. If you can't you can calibrate some other sensor against a first principles measurement.
Bitter magnets (yes, Bitter should always be capitalized as its after Francis Bitter, https://en.wikipedia.org/wiki/Francis_Bitter) have been around a long time, about 90 years. Superconducting magnets have been around over 100 years. Measuring ultra-high magnetic fields, both pulsed and continuous, has been around a very long time. I used to do it at fields up to 22T continuous in the '80's as a grad student, later worked in a lab that did it pulsed up to about 50T. Been out of the field for decades, no pun intended.
With those pulsed ones, when they went off, did you find yourself suddenly sitting upright, and then relaxing again?
Maybe I just spent too long around NMR spectrometers when I was a student. Although, with those, the magnetic field was steady, and it was the radio waves that were pulsed...
Measuring the Larmor frequency of hydrogen nuclei will give a very accurate value for the magnitude of the flux density. The main limitation is that the high field magnet will have significant gradients, with the frequency spectrum most likely looking like a hump, rather than a sharp spike.
Larmor Frequency being equal to the product of the Gyromagnetic ratio for the nuclide of interest and the applied magnetic field - give or take any chemical shift which maxes out about 10 ppm for hydrogen. Gyromagnetic ratio for hydrogen is 42.578 MHz/T.
Hardly surprising, when one is the current going into the magnet, and the other is the field generated by that current, and they are on different scales (there are two Y axes). Unless something is in the act of going horribly wrong, you would expect the magnetic field to be proportional to the current, because the power is proportional to that current (P=VI).
It's shifted up, because the whole shebang is sheathed in a superconducting magnet with a constant field of 11T, so when the current is 0A, the field is 11T.
I think the definition of fridge magnet is a bit loose.
Looks across the kitchen at the old DEW line radar system magnet stuck to the side of my fridge for no particular reason.
Its the one that my grandfather used on a rope to pick up tools he accidentally dropped into outboard motor testing\repair barrel,
Its one of those magnets you have to slide off the side of flat materials because you can't remove it by pulling on it.
Am I missing something?
45.22 Tesla (or 452,200 Gauss!) isn't actually all that strong!
I remember in certain secretive underground facilities in Nevada, we were doing 70+ Tesla (700,000 Gauss) by around 2005 already. In our Northern British Columbia Data centre doing a EMP/EMF/EMI/RFI/RAD test suite, we wanted to make sure our Tungsten + Copper + High Purity Iron + mu-Metal Radiation Hardening techniques used on all our supecomputer gear was designed to handle a CME (Coronal Mass Ejection) event, so I am quite sure at least one of the ten tonne test machines was emitting a 100+ Tesla (One Million Gauss) steady state and pulsed magnetic field for our EMF absorption/emissions test gear and that ANYONE who had ANY metal in their teeth or body ANYWHERE wasn't allow within 3 km of our data centre. (YES! I am aware blood has magnetically sensitive iron in it but our shielded test personnel were hundreds of metres away from the remotely operated test machines which included X-Ray and Gamma Ray emissions gear!)
Our largest stature workers who had no metal in their body were flown in on special assignment and wore SHEET TUNGSTEN and GOLD-FOIL covered Faraday Suits for these RAD-hardening tests which weighed something on the order of 100+ lbs (40 kg) so you had to be big and strong just to be in the area!
45.22 Tesla is quite "weak" as a concentrated EM field strength, so I am confused by this story because I am aware of MANY sites who have had MUCH MORE than this in steady state and pulsed form for at least the last 17 years! Plus, I am quite sure our pulsed test emissions and the initial rise-time of the steady state EM fields were picked up on monitoring sites around the globe. They would be fairly weak as they were absorbed by the multi-layers of EM-absorbing/Ferrous metal shielding but would STILL be picked up the very sensitive local and global EMP/EMF/RFI/EMI sensor instruments.
Again, this story is quite confusing as 45.22 Tesla is not all that large of an EM field!
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1200 Tesla at Institute for Solid State Physics at the University of Tokyo 2018 for one! (just look it up at Science Daily)
Then there's Los Alamos National Laboratory in new Mexico who did 100 Tesla (National High Magnetic Field Laboratory) and that was in 2012 and even our local UBC (University of British Columbia) in Vancouver was doing 60 Tesla in 2009 by a bunch of electrical engineering UNDERGRAD STUDENTS!
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I though the articale was a bit weird as 42 Tesla continous or pulses is NOTHING these days nor even as far back as the early 1990's! I remember getting RFC's and Peer Articles from colleagues who just broke 70 Tesla in 1993 using simple Liquid Nitrogen supercooling! They weren't even superconducting experiments but rather just supercooling of the normal electrical electromagnet components used for EMP/EMI/RFI protection testing on aerospace products!
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