Electromechanical Design of Nb3Sn Stress Managed Asymmetric Common-Coils

Stress-management of Nb₃Sn coils offers a promising approach for high-field magnets by reducing conductor stress. The combination of stress-management and the common-coils magnet type simplifies manufacturing processes, such as utilizing the coil former in reaction and impregnation tooling. The common-coils architecture provides an attractive solution for 2-in-1 dipole magnets, with its racetrack geometry facilitating manufacturing and potentially allowing the react-and-wind (R&W) technique for cost-effective large-scale production. A key contribution of this work is overcoming the need for pole coils to achieve field quality by introducing an asymmetric design using only common-coils. The PSI 2-in-1 dipole magnet, featuring eight stress-managed Nb₃Sn layers, employs bladder-and-keys technology for pre-loading at room temperature, eliminating the need for an aluminum shell or pads. The magnet includes two cable grades spliced in the low-field region, along with other features discussed in this paper. This work presents the conceptual design, including 3D magnetic design, mechanical analysis, and protection results.