Professor Tim Coombs
Professor Tim Coombs is a University Senior Lecturer in Engineering in the Engineering Power Group in the Electrical Engineering Division of the Engineering Department and is also attached to the Interdisciplinary Research Centre in Superconductivity. He is the Director of Studies for Part IIB Engineering at Magdalene.
Over the last 20 years, the EPEC (Electrical Power and Energy Conversion) superconductivity group has built an outstanding international reputation in several areas of superconductivity research. Its work spans from developing novel theoretical tools for understanding superconducting properties to achieving breakthroughs in the design of cutting-edge technologies. The group is now recognised as one of the strongest in the field, with an extensive portfolio of experimental techniques and mathematical analysis tools. Its publication record is internationally leading, with more than 210 papers published in high-impact scientific journals.
The group has been responsible for several notable firsts. For instance, the EPEC group was the first in the world to:
- Levitate a 40 kg flywheel on a superconducting bearing.
- Propose and use the H-formulation for solving the critical state, a technique that is now widely adopted.
- Build and test the world's first all-superconducting motor.
- Test the feasibility of using an HTS insert in a superconducting magnet with the goal of creating a 25 Tesla field.
- Propose and prove the principle of travelling wave flux pumps.
- Propose and demonstrate an inverter-based high-current flux pump for magnetising high-field HTS magnets.
Additionally, the group was among the first to conduct research on fault current limiters and remains unique in having done so across three different materials and various geometries. Several successful programmes have been completed, including one supported by EPSRC (EP/C512545/1) on the use of YBCO tape and a DTI-sponsored collaboration with Rolls-Royce on the use of MgB2 wire in fault current limiters. Other successful projects, such as the LINK programme with VA Technology, have contributed to the development of sophisticated modelling and measurement facilities.
Another area of expertise is superconducting magnetic levitation and the dynamics of different superconducting bearing systems. Beyond superconductivity, the group also investigates electrical distribution challenges, including studies on partial discharge in switchgear, seasonal power factor variations, and transformer design.
The modelling work that supports these investigations has been ongoing for more than 15 years, focusing on solving the critical state model and the E-J power law. Using commercial finite element modelling software, the group has produced results on magnetic field distribution, current distribution, magnetisation decay, energy loss, and quench behaviour in various superconducting structures, including bulks, tapes, wires, coils, and motors. These models incorporate both AC and DC external magnetic fields and transport currents. This internationally leading work includes:
- One of the first algorithms capable of calculating the critical state in two dimensions.
- The first modelling environment capable of describing heat propagation and losses in a fault current limiting thin film.
- The first use of the H-formulation, which has since become the standard method used by most researchers.
The group leads global research in superconducting magnetisation using flux pumping techniques and holds four groundbreaking patents covering both flux pumping methods and innovative approaches to patterning and arranging magnets. These advances enable high-power density machines, such as motors and generators (particularly for wind turbines), as well as high-value applications, including accelerator magnets, MRI systems, and MHD technologies.
Strong industrial collaborations have been established, with projects sponsored by companies such as BMW, Rolls-Royce, Areva, EDF Energy, VA Tech, and Applied Superconductor. The group also maintains strong partnerships with universities, including ongoing collaborations with the University of Manchester on the development and use of MgB2. Internationally, research links extend to institutions in Europe (Liege, Jena, and Barcelona) and the United States (Los Alamos, Argonne, and Boeing). Participation in an exchange programme with Tsinghua University, sponsored by the Royal Society, has further strengthened these global connections.
The group’s influence is reflected in its ability to attract high-profile academic visitors and a steady stream of highly motivated students, many of whom have been awarded scholarships and prizes.
In addition to research activities, the group has organised a series of workshops on the modelling and analysis of superconductors, as well as a summer school focused on sustainable energy.
Beyond academic research, the group's leadership has extensive industrial experience, with more than ten years in industry and authorship of over ten patents.