Electromagnetic-mechanical coupling analysis of high-temperature superconducting saddle and block-type coils wound with REBCO coated conductors

Abstract REBCO (RE = rare earth) coated conductor is the most promising high-temperature superconductor (HTS) for the construction of high-field magnets due to its excellent electromagnetic performance and high mechanical strength. However, for the REBCO coil, the non-uniform electromagnetic forces generated by the screening current can lead to severe structural deformation, local high mechanical stress/strain and degradation of REBCO tape performance, especially in high-field situations. Therefore, the electromagnetic and mechanical analysis of REBCO magnets, considering the influence of screening current, is crucial in their design and manufacture process. Besides the conventional pancake and racetrack coils, the HTS saddle and block coils, which serve as critical sub-components extensively utilized in superconducting accelerator magnets, have also emerged as the main superconducting coil configurations attracting significant research attention over the past decade. In this article, in order to investigate the electromagnetic and mechanical behavior of HTS saddle and block-type coils wound with REBCO coated conductors due to the screening current effect, a 3D numerical coupled model is adopted, in which the influence of coil structure deformation on the electromagnetic behavior is included. The REBCO saddle and block coil models investigated in this article are both dipole magnet structures, which comprise two pairs of identical REBCO coils. Considering the special structural configuration of both REBCO saddle and block-type coils, a new magnetic field correction method based on continuum mechanics is utilized to represent the interaction between the electromagnetic field and mechanical characteristics. Based on the comparison of numerical results with the experimental data, the reliability of the coupled electromagnetic-mechanical model is verified. Then, numerical simulations of the REBCO saddle and block-type coils are conducted and discussed based on the coupled models. The numerical analysis indicates the significance of the coupling effect in the electromagnetic-mechanical simulation of REBCO coils. In addition, the influence of several factors on the electromagnetic and mechanical responses of REBCO saddle and block-type coils is discussed in this study.