Depends on the machine type. Closed bore machines (the vast majority) use supercunducting electromagnets that are surrounded by liquid helium that creates a very strong magnetic field. To demagnetize them requires dumping the helium.
Some open bore machines use electromagnets, but they’re much less common and not as powerful.
the helium is liquid, which it only is when it is very very cold.
The superconductor will keep it’s magnetic field forever, as long as it’s superconducting, and it will stay superconducting while it is very very cold.
There is physically no way (as in, it is simply impossible, due to how our world works, not money, not people, not technology) to instantly “switch off” the magnet.
it needs to go above a certain temperature, to lose it’s superconducting nature, and it needs to do it at a pace that doesn’t dump a GINORMOUS amount of energy in this magnetic field instantly, because that would be even worse.
the fault here is in allowing anyone with any magnetic metal anywhere near an MRI. And whoever let that happen is going to have a very bad week.
No, the liquid helium cools the magnets to the point where they become superconductive. As to how that works exactly, I do not know. I don’t think I have the math for it.
Depends on the machine type. Closed bore machines (the vast majority) use supercunducting electromagnets that are surrounded by liquid helium that creates a very strong magnetic field. To demagnetize them requires dumping the helium.
Some open bore machines use electromagnets, but they’re much less common and not as powerful.
So the helium itself becomes magnetized, is that it?
the helium is liquid, which it only is when it is very very cold.
The superconductor will keep it’s magnetic field forever, as long as it’s superconducting, and it will stay superconducting while it is very very cold.
There is physically no way (as in, it is simply impossible, due to how our world works, not money, not people, not technology) to instantly “switch off” the magnet.
it needs to go above a certain temperature, to lose it’s superconducting nature, and it needs to do it at a pace that doesn’t dump a GINORMOUS amount of energy in this magnetic field instantly, because that would be even worse.
the fault here is in allowing anyone with any magnetic metal anywhere near an MRI. And whoever let that happen is going to have a very bad week.
No, the liquid helium cools the magnets to the point where they become superconductive. As to how that works exactly, I do not know. I don’t think I have the math for it.