Portable, high magnetic field charging of bulk superconductors for practical engineering applications

Lead Research Organisation: University of Cambridge
Department Name: Engineering

Abstract

The primary objective of this research programme is to develop portable, high magnetic field charging of bulk superconductors for practical engineering applications, with an end goal of producing a portable and commercially-viable high-field magnet system, by exploiting the remarkable materials properties of bulk high-temperature superconductors.
Bulk superconductors can be used, when cooled to cryogenic temperatures, as super-strength, stable permanent magnets generating fields of several Tesla, compared to the 1.5-2 Tesla limit for conventional permanent magnets, such as neodymium magnets (Nd-Fe-B). This makes them attractive for a number of engineering applications that rely on high magnetic fields, including compact and energy-efficient motors/generators with unprecedented power densities and compact and portable magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) systems. It is now also possible for scientists to use high magnetic fields to exploit the magnetism of a material for controlling chemical and physical processes, which is attractive for magnetic separation and magnetic drug delivery systems (MDDS), for example. With the continued development of conventional superconducting magnets and the achievement of higher magnetic fields, even the chemical and physical processes associated with diamagnetic materials, which make up many of the materials found on earth, are significantly influenced. This has led to observations of the Moses effect (where the free surface of water is deformed by a magnetic field of several Tesla), magnetic levitation of diamagnetic materials, and magnetic orientation of organic polymers and gels and carbon nanotubes, which is particularly attractive for improving crystal growth of organic semiconductors and other materials.

This project aims to address to problem of practical bulk superconductor magnetisation and the major objectives of the project are as follows:
1. Tailoring the material processing and properties of bulk superconductors and magnet geometry, with any necessary reinforcement, towards practical high-field applications;
2. Extension of numerical techniques to model the bulk superconductor properties and predict their performance quickly and accurately, including simulation of electromagnetic forces and mechanical properties of bulk superconductors for complete electromagnetic-thermal- mechanical analysis;
3. Development of PFM techniques by combining numerical and experimental results;
4. Design, construction and testing of two types of compact and efficient pulsed field charging systems to produce a portable and commercially-viable, high-field magnet system;
5. Achieving trapped fields in bulk superconductors practically to a level beyond 5 Tesla;
6. Design and development of industrially-led, high-field magnet systems for bespoke applications.
The outcomes of this project would have an important impact on many high-field engineering applications, such as rotating machines (motors and generators), magnetic separation, portable MRI machines and MDDS. This project will accelerate the development and commercialisation of such systems based on bulk superconductors. Potential applications of such technology have been severely limited commercially because of the inflexible, costly and/or inefficient magnetisation fixtures used to date, although some demonstrator devices exist. The successful development of a portable, high magnetic field charging system will bring about a step change in applications that currently use permanent magnets, as well as technology enabled by the high fields possible from bulk superconductors.

Publications

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