6. Superconducting materials

They were almost forgotten, even though they have the remarkable property that their electrical resistance drops below a certain critical temperature, generally between 4 and 20 K. These materials, which are already quite old, are mostly based on Nb-Ti and Nb-Sn. To further enhance their intrinsic properties, the superconducting filaments are finely divided and embedded in a copper-based matrix, the whole being obtained by co-drawing alloy rods arranged in a copper tube. The manufacturing process, which has been perfectly mastered for decades, enables windings to be produced to create intense magnetic fields. A fully superconducting alternator was even built in the 1970s. But the cost of cryogenics (based on liquid helium) has prevented these products from finding their way into the cable sector, as the overall energy balance is negative.

However, in 1986, a thunderclap...