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 owing to its excellent electromagnetic performance and high mechanical strength. However, for the REBCO coil, the non-uniform electromagnetic forces generated by the screening current will lead to severe structure deformation, local high mechanical stress/strain and degradation of REBCO tape performance, especially in high-field situation. 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 the critical sub-components extensively utilized in the superconducting accelerator magnet, have also emerged as main superconducting coil configurations attracting significant research attention over the past decade. In this article, in order to investigate the electromagnetic and mechanical behaviors of HTS saddle and block-type coils wound with the REBCO coated conductors due to the screening current effect, the three-dimensional (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 the dipole magnet structure, which is comprised of two pairs of identical REBCO coils. Considering the special structure configuration of both REBCO saddle and block-type coils, a new magnetic field correction method based on the continuum mechanics is utilized to represent the interaction between electromagnetic field and mechanical characteristics. According to the comparison of numerical results with the experimental data, the reliability of coupled electromagnetic-mechanical model is verified. Then, the 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 coupling effect in the electromagnetic-mechanical simulation of REBCO coils. In addition, the influences of several factors on electromagnetic and mechanical responses of REBCO saddle and block-type coils are discussed in this study.