I believe the way it used to be done was magnets made by inducing a moving current in a ring shaped superconductor which needs to be at c. 2 kelvin to maintain

I believe the way it used to be done was magnets made by inducing a moving current in a ring shaped superconductor which needs to be at c. 2 kelvin to maintain superconductivity? They are supercooled by liquid Helium, which then has it's compression system cooled by a liquid Nitrogen compression system. That said, I do recall reading about a fancy new higher temp superconductor which would allow for a much smaller torus to be made. This may be using that system. I'm not completely up to date.