Speaker
Description
Demo4 is a unique, high-field device comprised of a total forty-four high-temperature superconducting (HTS) coils made from stacked rare-earth barium copper oxide (REBCO) tapes in a compact, spherical tokamak (ST) configuration. The complete magnet set consists of twenty-eight toroidal field (TF) coils manufactured into fourteen TF limbs, and sixteen poloidal field (PF) coils in two PF stacks. This magnet system is designed to operate in a relatively low current regime, compared to other fusion machines, of up to several kiloamperes steady state at a base temperature of 20 K. Demo4 allows us to cost-effectively demonstrate background magnetic fields and compressive loads representative of a full-scale ST fusion pilot plant and gain hands-on experience in both normal and fault condition system operations.
To derisk system assembly and operations, the complete set of HTS coils needed for Demo4, including several spare coils, have been rigorously tested both mechanically and electrically throughout their manufacturing processes. Here, I present our performed quality control checks, including nominal, electrical measurements of all HTS coils at 77 K in liquid nitrogen. This talk summarises the challenges faced during coil characterisation, the data acquisition and analysis, and how we have subsequently used these results to inform our decision for optimal TF coil allocation in final system assembly.
