Making Superconducting Magnets

Superconductivity in a Nutshell

First, a brief primer on superconductivity. If you want to learn more than is covered here, read our article Current in a Cape and Thermal Tights. If you know this stuff already, skip ahead to the next section.

At the lab, we make the liquid helium used in our magnets, then store or transport it in dewars.

Electricity, of course, is awesome: We couldn't enjoy our microwaves, stereos or computers without it. But it has its downsides, one of which becomes immediately apparent when we accidentally touch a light bulb: Ouch! Turns out that the electrons moving through a wire zigzag very inefficiently, bumping into things and creating the friction we feel as heat. That heat is wasted electricity.

Superconductivity is electricity without the unwanted side effect of heat. It's elegant and efficient: Electrons zip through wires with no collisions or friction at all. And because there's nothing to slow them down, electrons in a superconducting state can go on virtually forever, with little to no help from the local utility company.

But there's a catch: Superconductivity occurs only at extremely low temperatures. For most known superconducting materials, those operating temperatures are so low you need liquid helium, the coldest liquid in the universe, to produce them. Scientists go to a lot of trouble and expense to make this stuff: Helium liquefies at -269 degrees Celsius, or -452 degrees Fahrenheit.

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