Study on the Arrangement of REBCO Double-Pancake Coils with Different Critical Currents in 30-T Superconducting Magnets

We have designed a 30-T superconducting magnet for important experimental facilities in condensed matter physics research. The critical current of rare-earth barium copper oxide (REBCO) tapes directly or indirectly affects the electromagnetic margin, central magnetic field, hysteresis losses, field homogeneity, and screening current–induced stresses (SCIS) of the magnet. Given the poor critical current consistency of REBCO tapes at 4.2 K and their complex field-dependence, the arrangement of double-pancake (DP) coils is crucial in superconducting magnets. Based on measurements of over 100 REBCO tapes at 4.2 K and under an 8-T perpendicular field, we studied the arrangement of DP coils with different critical currents to assess their impact on the electromagnetic margin, central magnetic field, hysteresis losses, field homogeneity, and SCIS of the 30-T superconducting magnet. The results indicate that, depending on the magnet’s requirements for different performance aspects, DP coils wound with higher critical currents should be positioned in locations with lower sensitivity to critical current. This approach serves to reduce the operating factor, screening current–induced field (SCIF), peak hoop SCIS, and losses, respectively. These findings provide valuable insights into the design of ultra-high-field REBCO superconducting magnets and arrangement of DP coils.