Electromagnetic Design of a 16–9 T High Field Double Superconducting Magnets System for Nuclear Demagnetization Refrigerator

A double superconducting magnets system with a high-temperature superconductor (HTS) magnet and a low-temperature superconductor (LTS) magnet is designed for a nuclear demagnetization refrigerator for experimental study on quantum physics. The HTS magnet will generate 16 T field for physical experiments and the LTS magnet will generate 9 T field for nuclear demagnetization refrigeration. Electromagnetic design steps, including linear programming, nonlinear optimization, and current density gradation for both HTS and LTS magnets, are introduced in detail. Results show that the field requirements are satisfied. Current margin and stress are well considered for Yttrium Barium Copper Oxide conductor, Nb3Sn wire, and NbTi wire used in the magnets.