Originally posted by Soothfast
45 teslas. So…is that a lot?
The magnets used in MRI machines are around 10 tesla's or thereabouts. One of them killed a 5 yo boy when they activated the magnet, one of the hard fast rules is to not have any magnetic metals anywhere in the MRI room.
So this one day, some assshole left a metal fire extinguisher in the room, actually on the far wall away from the MRI itself.
It didn't matter, when the magnet was turned on, it caused the fire extinguisher to fly through the air and inside the round portion where your head is located for the scan. So it hit the little boy and killed him instantly because it was going so fast.
That is a magnet 1/4th or less the power of those big guys.
You have seen perhaps the electromagnets used in scrap iron yards where a crane hauls this magnet about a meter wide and plops it down on say, a car, and they turn on the field and it is strong enough to lift the whole dam car right into the air and then deposit it in a crusher.
Those magnets are maybe 2 teslas or so.
That can give you a rough idea of the power of these newer ones at 30 and 40+ tesla.
A Tesla is 10,000 Gauss and a typical refrigerator magnet might be a few hundred Gauss so you can see by the numbers, a 45 Tesla magnet is 450,000 Gauss! We are talking major force here.
At that level, the metals used to make the magnets can get deformed and the whole thing blow up like a bomb if they don't make the internal structure strong enough to take the tons and tons of force generated so you don't just take some kind of iron core and wrap regular magnet wire around it, you have to have very well designed core material and a LOT of cooling water to keep the thing from melting on the spot, those big puppies take something like 20 MILLION watts to run, so you can see why they use water at 150 odd liters per SECOND to keep the magnets cool.
And that is only regular magnets, some of them use superconductors which have to be cooled in some cases to with in an inch of absolute zero, say 3 or 4 degrees Kelvin and the higher temp ones, at liquid nitrogen temps.