High-Field Insert With Bi- and Y-Based Tapes for 25-T All-Superconducting Magnet

Recently, a superconducting magnet with a center field of 25 T at 4.2 K and a warm bore size of 32 mm in diameter has been designed and fabricated at the Institute of Electrical Engineering (IEE), Chinese Academy of Sciences. The 25-T superconducting magnet consists of NbTi, Nb3Sn, and high-temperature superconducting inserts. The YBCO and Bi-2223 inserts have been designed, fabricated, and tested in liquid helium at IEE to prove the technical feasibility to achieve the target of 25 T. The YBCO insert has an inner diameter, an outer diameter, and a height of 24, 65, and 204 mm, respectively, whereas the Bi-2223 insert has an inner diameter, an outer diameter, and a height of 120, 212, and 250 mm, respectively. The central operating magnetic field of the Bi-2223 insert can reach up to 5.8 T with a design operating current of 150 A. As for the YBCO insert, a 5.3-T central magnetic field can be obtained at the design operating current of 150 A. Quench simulation was also performed. Test results show that the combination of these two insert coils can generate a center magnetic field of 11 T at 4.2 K, and the effectiveness of the quench protection system is also validated.