Screening Current-Induced Magnetic Field in a Noninsulated GdBCO HTS Coil for a 24 T All-Superconducting Magnet

A 24 T all-superconducting magnet, consisting of a 9 T GdBCO high-temperature superconducting (HTS) insert and 15 T low-temperature superconducting (LTS) outer coils, has been manufactured and tested at the Institute of Electrical Engineering, Chinese Academy of Sciences. A central magnetic field reduction and drift in the superconducting magnet system were caused by the screening current induced in the GdBCO HTS coil. Therefore, it is crucial to estimate the screening current-induced magnetic field in the HTS coil. In this paper, the magnetic field generated by the screening current was numerically calculated based on magnetization analysis. Three related experiments were performed at 4.2 K to verify the simulations: First, charging the HTS coil at different ramping rates; second, charging the LTS coils with central field of 10.82 T first and the HTS coil subsequently; and third, charging the LTS coils with central field of 15 T first and the HTS coil subsequently. The calculation results show a good agreement with the measured data.