Metal as Insulation REBCO Racetracks Coils: Development, Fabrication, and Cryogenic Testing at CEA Paris-Saclay

CEA-Saclay started the development of Metal-as-Insulation racetrack coils in as part of the High Field Magnet (HFM) CERN program. This winding method aims to significantly reduce the amount of High Temperature Superconductor material required to achieve relatively high magnetic induction and associated forces. CEA's objectives are to fabricate and test a small racetrack coil to benchmark numerical models with experimental data. The insulated coil counterpart, operating at lower current densities and targeting high fields, is studied by CERN as part of the HFM program. This paper focuses on the design, fabrication and quench tests at 4.2 K of two specific coils: a single racetrack coil and a double racetrack coil (DRT), each with 140 mm long straight part and 27 mm inner diameter. Both coils achieved very high overall current density (above 2300 A/mm²) and significant peak magnetic field on the conductor (8.5 T and 12.3 T respectively). A central magnetic field above 5 T was reached after a quench at 4.3 T in the DRT.