Estimation of Losses in the (RE)BCO Two-Coil Insert of the NHMFL 32 T All-Superconducting Magnet

Abstract

(RE)BCO commercial coated superconductors have been gaining an increasing interest due to the potentialities of using them in high-field magnets. The leading project is the 32 T user magnet recently tested successfully at full field at the National High Magnetic Field Laboratory (NHMFL), Tallahasee, FL, USA. This state-of-the-art high-field all-superconducting magnet, bath-cooled at 4.2 K, is comprised of a two-nested-coil insert pancake-wound with (RE)BCO tapes supplied by SuperPower Inc. and a multicoil low temperature superconductors (LTS) outsert. To ensure the magnet's reliable operation, it is important to estimate the hysteresis losses. Such an estimate will allow implementing safe operational procedures to avoid premature quenching and, in the worst case scenario, insert failure. The insert coils have thousands of turns with notable variations in the critical current. Therefore, estimating the losses in such a large superconducting magnet presents a significant challenge. We propose here a new approach relying on a multiscale scheme to achieve a high computational efficiency. This new method is flexible enough to simulate different sections of the entire insert with the right level of detail while providing a larger computational speed than other approaches using the finite element method. Estimates of the hysteresis losses in the insert coils for a ramping operation sequence are presented.