Understanding radiation damage mechanisms in high temperature superconductors for fusion applications

Rare-earth barium copper oxides (REBCO) are the only class of high-temperature superconducting (HTS) materials that have been developed into commercial wires with an engineering performance that is suitable for use in the high field magnet assembly in small fusion tokamaks. One of the critical aspects we must understand before deciding to deploy these materials in a fusion reactor is how they respond to ionising radiation such that they can retain adequate performance for the lifetime of the reactor when exposed to high energy neutrons and a significant flux of gamma rays.
 
The manufactured microstructure, local oxygen stoichiometry and the distribution of flux pinning centres play crucial roles in determining the superconducting properties, but the exact mechanisms by which radiation alters these microstructural features are unclear. Different types of radiation can cause point defects and larger damage cascades, or stimulate radiolysis effects, but the quantitative relationships between initial structure, radiation type, energy and flux, specific damage processes and the final engineering properties are unknown. An understanding of these effects is needed in order to predict how the magnet performance may change during the lifetime of a reactor.  The student will work with facilities at the Culham Center for Fusion Energy, and design experiments on the Diamond Synchrotron, to develop a mechanistic understanding of how the defect structure in REBCO is affected by radiation, and how these changes control the superconducting properties.