The project has experimentally analysed the performance of superconducting wires, and investigated the mechanisms by which state-of-the-art artificial pinning centre (APC) and doping techniques enhance that performance. For niobium-tin (Nb3Sn) superconductors, compositional inhomogeneity limiting wire performance has been characterised in relation to wire design, and flux pinning models have been developed for APC wires. This is an important development since Nb3Sn is a candidate not only for future high-energy colliders, but also for other applications that can benefit from its higher current density at higher fields (10 T-16 T) and its high transition temperature (~17 K) wrt to Nb-Ti: medical imaging devices (MRI and NMR), cancer treatment particle accelerators and industrial materials analysis applications.
For magnesium diboride (MgB2), work has focused on enhancing its suitability for high magnetic field industrial applications and on electromechanical characterisation. Advancements in YBCO coated conductors for high field applications have also been made, including the development of improved quality assurance methods, for which an intellectual property (IP) disclosure has been made. Scientific articles have been published in journals and conference proceedings during the project.
High Temperature Superconducting thin films have also been studied. Two deposition methods for thallium-based coatings have been developed, resulting in enhanced morphology and superconducting properties, and a new study has been launched to realise their potential for beam screen coatings. Superconducting RF cavities are used in particle accelerators, in industrial free-electron lasers and energy-recovery linear accelerators. In the field of radiofrequency (RF), several methods for depositing Nb and NbN coatings have been optimised and factors limiting performance (e.g. surface preparation) have been identified and addressed. Electrohydraulic forming has also been studied for cavity applications: comparative studies of different forming techniques of Cu and Nb have been performed, assessing the microstructural effects of different strain rate processes, in order to optimise the shape and performance of complex structures. Two IP disclosures have been issued in relation to these activities, ~20 scientific publications have been made, and results have been presented at an international conference.
For cryogenic refrigeration, the work focused on efficient cooling of high-field superconducting magnets and on an energy-efficient refrigeration cycle based on a neon-helium (“nelium”) gas mixture. For magnet cooling, a numerical model for transient heat transfer in superfluid helium and in the confined geometry of coolant micro-channels has been successfully developed and validated with experimental data. Equation of state models for the thermodynamic properties of nelium and other binary cryogenic mixtures have also been successfully developed and validated experimentally. A design study for a nelium cryogenic refrigerator has been undertaken to validate the potential performance improvements and industrial applicability of this technology; a test rig has been designed, built and used to validate turbocompressor performance operated with these gas mixtures.
