A century of superconducting technology

Cryogenic Engineering was the enabling technology by which Heike Kamerlingh Onnes discovered superconductivity in 1911. Thanks to years of careful development, Leiden had become the world centre for cryogenics and remained the only source of liquid helium for many years. Shortly afterwards, Kamerlingh Onnes speculated on the possibility of building a superconducting magnet, but was disappointed to find that superconductivity in the metals he had measured: mercury, tin and lead, was quenched by quite modest fields. Despite many advances in the theory, it was to be another 50 years before superconducting technology really got off the ground with the discovery, largely in the USA, of a new class of hard 'type 2' superconductors which could retain their superconductivity up to very high magnetic fields. Starting with small laboratory solenoids, a new industry was borne, which then expanded into larger scale applications like NMR spectroscopy, clinical MRI and large particle accelerators. The discovery of High Temperature Superconductivity promised a further expansion of the industry into new application areas, but this hope has yet to be fulfilled. Recently however the performance of HTS conductors has dramatically improved with the advent of oriented thin film YBCO tapes and it is hoped that these conductors will open up new applications for superconductivity, perhaps in electrical power engineering.