Numerical Study of the Screening Current Induced Magnetic Field Intensity in the HTS Insert of a 16-T Superconducting Dipole Magnet

To obtain a dipole field of 15–20 T or even higher, magnet fabricated with high-temperature superconducting (HTS) insert coils and low-temperature superconductor (LTS) coils outside is a feasible way presently. The superconducting magnet group at the Institute of High Energy Physics, Chinese Academy of Sciences is designing a 3-T HTS coil to be inserted into a 13-T Nb
₃
Sn dipole magnet at 4.2K. The HTS insert is composed of four double-pancake coils, which are wound with the 2-mm thick and 9-mm wide HTS cables. The cable is implemented by in-plane bending stacked HTS tapes directly to realize the transposition. Due to the large dimension of the basic current-carrying element, coated conductors, such as rare-earth barium copper oxide (ReBCO), are strongly magnetized during operation, which leads to a significant degradation of the magnetic field quality of superconducting accelerator magnets.
TA
formulation is employed to simulate the screening current within the cable, and the numerical model of the coils has been built to quantify the contribution of the screening current–induced field effect on the field quality. In addition, the loss of the HTS cable used for the insert coils at the ac and dc conditions are analyzed.