Radiation damage in superconducting materials for Fusion applications

Lead Research Organisation: University of Oxford
Department Name: Materials

Abstract

Future designs of fusion power machines will all require large superconducting magnet windings, and these superconductors will, in service, be subjected to high fluxes of energetic particles, most seriously the 14 MeV neutrons generated in the deuterium/tritium fusion reaction. Modern designs of small tokamaks usually rely on high temperature superconducting tapes to generate the large magnetic fields required for plasma confinement, and it is an engineering priority to generate these fields in as small a volume as possible.

However, little is known about the effect on the superconducting properties of the lattice damage resulting from the impact of energetic particles, especially in 2nd generation high temperature superconducting tapes where the ceramic superconducting layer that carries currents of hundreds of amps is only 1 micron thick. Much of the damage will be in the form of clusters of point defects in irradiation cascades, or possibly the dissolution of nanoscale flux pinning particles, and so can only be studied by very high resolution techniques - many of which have been developed in previous work on radiation damage in fission materials.

The project will use advanced electron microscopy techniques to identify the key damage mechanisms in a range of different superconducting materials exposed to high energy particles, and to correlate these with direct superconducting property measurements. National ion beam damage facilities (at Surrey and Huddersfield Universities) will also be used to study the effect of proxy irradiation by heavy ions, and to correlate the ion damage mechanisms with those found in n-damaged materials provided in both bulk crystals and 2nd generation tapes by our partners in the University of Vienna. We will explore novel measurements of ion damage degradation with the superconductor below its transition temperature, and if possible carrying current, to be as close to the real operating conditions as possible. This will be the first time that this in-situ damage experiment will have been attempted.

The primary aim of the project will be to identify the maximum neutron dose that a magnet winding can be subjected to without severe and irreversible damage, as fundamental input data for the designers of next generation tokamak machines. The novelty of the approach is to take techniques well known to the fission community in steels and zirconium alloys and to apply them to the novel ceramic materials now being selected for fusion magnets. The project is aligned with the EPSRC theme of Energy. This studentship is a collaboration with a local small company, Tokamak Energy.

The Themes are:
Energy
Physical sciences

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509711/1 01/10/2016 30/09/2021
1922085 Studentship EP/N509711/1 01/10/2017 31/03/2021 William Iliffe