The Physics of the High-Temperature Superconducting Dynamo and No-Insulation Coils

High-Tc superconducting (HTS) dynamos are a fascinating topic as practical engineering research preceded fundamental understanding, a lead then maintained for at least a decade. These devices, counter to expectation, produce a dc voltage where ‘textbook’ electromagnetism would predict a zero dc component. Simply by replacing a normal conducting stator in a standard dynamo with HTS conductor a dc — auto-rectifying — effect is created. This thesis reports my work in uncovering and codifying the underlying mechanism that gives rise to this effect — namely the broken symmetry that is usually present with Ohm’s law. An explanation of the dc voltage then leads to an explanation of the internal resistivity of such devices, which in turn allows more efficient dynamos to be designed, and modelled. The underlying logic of the HTS dynamo mechanism is also sufficiently strong to predict a complimentary electromagnetic device, a semiconducting dynamo, which remains to be experimentally verified.

Ultimately, such HTS dynamos could be used to energise powerful HTS magnets. The modelling techniques developed in this thesis also provide insight into the operational behaviour of no-insulation coils (NI coils). Such coils are extremely robust to mechanical, thermal, and electrical stresses and faults. A simple model of such coils is presented that captures their essential physics with enough fidelity to predict shielding and magnetisation currents inherent with HTS conductors and turn-to-turn current flow. These two technologies represent key topics for the future of high field HTS magnet technologies and their supporting systems.