Abstract

In the months following the discovery of high-temperature superconductors (HTS) Time magazine ran the coverline “Wiring the Future – The Superconductivity Revolution”. But, 20 years later, you might be forgiven for wondering ‘what revolution?’ Progress has been much slower than expected. Getting a practical handle on the complex HTS materials has been at least as challenging as understanding the mechanism of high tempeartiure superconductivity (is there still another Nobel prize in play?1). But commercial applications of HTS are emerging2, and, as key aspects of the materials technology are close to being mastered, we can confidently expect many more. Much early excitement was driven by the perception that cooling in liquid nitrogen was both much more straightforward and much less expensive than cooling in liquid helium. But these criteria are far from sufficient: like any other new technology, HTS must compete in all the usual ways, not only in cost but in technical capability and availability as well. No technology for large scale applications is feasible without conductors that can transport very high current densities 105-6 A/cm2 without loss. A key technology hurdle, now overcome, was to texture forms of HTS such that misorientations from grain to grain are only a few degrees or less3-4. Many key components of the electric utility grid have now been demonstrated with HTS . The Large Hadron Collider at CERN incorporates more than 1000 HTS current leads for the main ring magnets, while new devices such as fault current limiters and reactive power devices are being made from HTS . In my talk I will describe some of the key materials problems that have been overcome and address some of the foreseeable market applications for HTS . 1. Zaanen, J. et al. Nature Phys. 2, 138–143 (2006). 2. Malozemoff, A.P., Mannhart, J. & Scalapino, D. Physics Today 58, 41–47 (April 2005). 3. Larbalestier, D.C., Gurevich, A., Feldmann, D.M. & Polyanskii, A. Nature 414, 368–377 (2001). 4. Clarke, J. and Larbalestier, D. Nature Physics 2, 794-796 (2006).