Principal applications of superconductors

If you ask the man in the street about the applications of superconductivity, he usually mentions levitating trains. He also mentions the possibilities of these materials for electrical cables. Rarely does he know that superconductivity has enabled the development of high-quality and widespread medical imaging, MRI (Magnetic Resonance Imaging), and the remarkable investigative tools of high-field spectrometers. He is certainly familiar with the ITER reactor, but is often unaware that superconductivity is paradoxically indispensable for confining plasma heated to hundreds of millions of degrees.

In 2004, the worldwide market for superconductivity reached 3.65 billion euros, primarily involving conventional, low-critical-temperature superconductors. The volume percentages in 2004 were 97.8%, 1.5% and 0.7% respectively for NbTi, Nb ₃ Sn and SHTC (high critical temperature superconductors). Indeed, while SHTCs enable operation at higher temperatures than NbTi, they have not yet reached a sufficient degree of industrial maturity, in terms of both performance and cost, to be used in products, but this situation should change in the medium term, given the rapid developments in high-critical-temperature conductors.

Today, superconductors are mainly used industrially to create moderate to strong inductions (1.5 T to over 20 T) in volumes that can be considerable (up to hundreds of m ³ ). These devices exploit the high current densities of superconductors, combined with zero losses at constant induction. They also provide exceptional temporal stability of magnetic induction, which is essential for certain applications. In this dossier are discussed current industrial applications of superconductors with the "conventional" materials, NbTi and Nb ₃ Sn. The cost, expressed in $/(kA × m) (for a conductor one meter long and carrying 1 kA), allows comparison between conductors, but corresponds to a given magnetic induction and temperature. By way of comparison, copper costs around $10/(kA × m).

Other applications (new functionalities/new equipment and improvements to conventional resistive devices) are covered in a second dossier [D 2 705] .

The reader is referred to the documents "Superconductors, theoretical bases" and "Superconductors, theoretical bases". , "Superconductors, wire...