Warren Smith
Durham University
Co-hort year: 2025
I completed an Integrated Master’s in Physics at Imperial College London in 2025. I was greatly interested in Fusion Energy even before beginning my undergraduate degree due its potential as a clean, safe, and abundant energy source that could one day replace fossil fuels. However, it was an internship at Oxford Instruments, in which I was part of the Superconducting Magnet Research Team, that drove me to pursue a PhD in superconductivity as an enabling technology for Fusion Energy.
One of the main routes for fusion is Magnetic Confinement Fusion (MCF), for which superconducting magnets are essential in order to build effective and energy-efficient reactors; most likely, we will need to make use of high-temperature superconductors (HTS), since they can be up to five times more energy-efficient than their low-temperature counterparts (due to a smaller cooling load [1]), and they can withstand much stronger magnetic fields, enabling more compact and effective reactors. These magnets have to operate in strong magnetic fields and under extreme strain from the large magnetic forces involved, and so understanding how the performance of HTS magnets changes in these conditions is imperative for the design of future fusion reactors (e.g., STEP: [2]).
My PhD project will be focussed on making measurements of critical current density (the maximum current density that a superconductor can withstand before losing its superconducting properties) on miniaturised samples of HTS tape under extreme strain, with differing magnetic field strengths and orientations at various temperatures. Using miniaturised samples (~10-100μm) facilitates critical current density measurements at Tokamak temperatures (~20K [2]) where the total critical current in a full-scale tape (~ 1-10mm) would be prohibitively large for most research set ups; the sample is not so small at this miniaturised scale, however, that reduced dimensionality effects significantly alter the superconducting properties. The aim is of this research is to explore why the measured values of critical current density in state-of-the-art materials in high magnetic fields is typically two to three orders of magnitude smaller than theoretical predictions, and to investigate how HTS materials can be optimised for use in commercial fusion reactors.
[1] – Fusion energy technology – Tokamak Energy
[2] – STEP | UKAEA Fusion Energy
Supervisors
