The Second Version

11/01/07

Superconductivity, Where Art Thou?

Superconductivity is the phenomenon in which a material, below a certain carachteristic temperature will allow an electrical current to pass with virtually zero resistance - this also mean the current density in such a material can be very high. In-depth details are available here, because I don't want to concentrate on that subject now.

Superconductors are very interesting materials in many fields. Not only they can dramatically cut electricity transmission losses, but they also can be used to build transformers, electromagnets, motors and generators much more powerful, efficient, small and light than current ones. And those nifty quantum devices known as SQUIDs.

Of course, there also are military applications, in the form of electromagnetic guns and all-electrical ships, and possibly EMP weapons. In theory, it is possible to store electricity for long periods as a current circulating in a superconductor ring or loop: such a device could resolve energy storage problems.

Superconductors wires are already used in some practical applications - mainly, NMR machines but also short-range power transmission lines. The main limit is the cooling needs: even the best superconductors have transition temperatures of 138 - 150 K, which require liquid nitrogen cooling. Liquid nitrogen is, nowadays, a common and relatively cheap coolant, but it remains not the most practical solution ever (liquid methane may also work, but it's not a huge improvement).

I'm not sufficiently expert of the matter to have an informed opinion on whether room temperature superconductivity will be possible, but the fact that many brilliant minds working hard in advanced facilities only managed a 150 K transition temperature does not make me optimistic.

There are also engineering problems: making useful lengths of wires and cables of materials that are ceramics is not so straightforward, as it's the development of appropriate insulation - electrical, but also thermal. However, when it's possible and convenient to install a liquid nitrogen system, I think we'll see more and more superconductors in the future.

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