A 24 T all-superconducting magnet operating at 4.2 K, consisting of a 9 T YBCO high temperature superconducting (HTS) insert coil and 15 T low temperature superconducting (LTS) coils, has been developed by Prof. WANG Qiuliang’s Group at the Institute of Electrical Engineering of Chinese Academy of Sciences, which makes China the fourth country in the world achieve a center field above 24 T in the all-superconducting magnet, and the other three are United States, Japan, and Korea.

Compared with BSCCO HTS insert coils, REBCO coils have higher upper critical field, critical current and operating stability, which means that the REBCO coils can obtain a center magnetic field above 24 T. At present, only three groups in the world could meet the goal, namely National High Magnetic Field Laboratory in United States, High Field Laboratory for Superconducting Materials in Tohoku University at Japan, and SUNAM Co. Ltd in Korea.

Supported by the National Natural Science Foundation of China, Prof. WANG’s group adopted the grading coil design method to increase the safety margins of the magnet, and also manufactured superconducting joint with excellent performance with specially designed devices. The YBCO insert coil can generate a center magnetic field of 1.62 T at 77 K with an operating current of 32 A, and at generate 9 T central magnetic field under 15 T background LTS coils at 4.2 K, at an operating current of 167 A. The maximum magnetic field obtained is 24.3 T.

The achievement of a 24 T all-superconducting magnet represents that China takes a leading position in construction of all-superconducting magnet with extremely-high field, and has accumulated sophisticated experiences and techniques in the field of high field superconducting magnets. It supplies good references to manufacture Ghz Nuclear Magnetic Resonance (NMR) magnets and large-scale scientific facilities with extremely-high magnetic field in the near future.