A CORC® cable insert solenoid: the first high-temperature superconducting insert magnet tested at currents exceeding 4 kA in 14 T background magnetic field

The results presented in this Letter describe the successful test of the first high-temperature superconducting multi-tesla insert solenoid tested at currents exceeding 4 kA while operating in a background magnetic field of a low-temperature superconducting outsert magnet. A 45-turn insert solenoid, wound from 19 meters of CORC (R) cable, was designed to operate at high current, high current density, and high hoop stress in high magnetic background field; a combination that is essential in the development of low-inductance, high-field magnets. The CORC (R) cable insert solenoid was successfully tested in liquid helium in background magnetic fields of up to 14 T, resulting in a combined central magnetic field of 15.86 T and a peak magnetic field on the conductor of 16.77 T at a critical current of 4404 A, a winding current density of 169 A mm(-2), an engineering current density of 282 A mm(-2), and a JBr source stress of 275 MPa. Stable operation of the CORC (R) cable insert magnet in its superconducting-to-normal transition was demonstrated, during charging at rates of 20-50 A s(-1), without inducing a quench. The results are a clear demonstration of the major benefits of this multi-tape CORC (R) magnet conductor in which current sharing between tapes is possible, thereby removing some of the stringent conductor requirements of single-tape magnets. The CORC (R) cable insert solenoid demonstrated operation at about 86% of the expected CORC (R) cable performance and showed no significant degradation after 16 high-current test cycles in background fields ranging from 10 to 14 T. CORC (R) cables have matured into practical and reliable high-field magnet conductors, achieving important high current, high current density, stress tolerance, and quench protection milestones for high field magnet technology. They have established a straightforward path towards low-inductance magnets that operate at magnetic fields exceeding 20 T.