Progress in the STEP Programme Toward Understanding REBCO Coated Conductors in the Fusion Environment

The UKAEA's Spherical Tokamak for Energy Production (STEP) programme aims to demonstrate the ability of low aspect ratio tokamaks to generate net electricity from deuterium-tritium (DT) fusion. As STEP have selected REBCO coated conductor (CC) as the current carrier in most magnet systems, understanding how REBCO CC responds to the energetic particle environment of a compact tokamak is crucial, especially given reported changes to the properties of REBCO following neutron irradiation. The STEP confinement system materials group has developed a plan to thoroughly test and validate the superconducting properties of REBCO under conditions as close as reasonably possible to those within STEP prior to its construction. Here our progress in carrying out this experimental plan is presented, followed by details of experiments still in development.