Design of a 5T Conduction-Cooled Magnet for the Quantum Materials Resonant Scattering Experimental Station

This paper presents the design and optimization of a split-type superconducting magnet for the Quantum Materials Resonant Scattering Experimental Station (QMRSES) at the Hefei Advanced Light Facility (HALF). To achieve a central magnetic field of 5.0 T within the severe spatial constraints of a 550 mm spherical cryostat, the magnet's topological structure was optimized. A graded winding technique was adopted, employing rectangular NbTi wires in high-field inner regions and round wires with varying diameters in outer regions to maximize the engineering current density. The magnet operates under conduction cooling using a 4 K Gifford–McMahon (G-M) cryocooler. A suspension system utilizing G-10 rods was designed to balance mechanical rigidity with minimal thermal conduction. Comprehensive Finite Element Method (FEM) simulations were conducted, including a coupled structural analysis considering winding pre-tension, aluminum over-banding, thermal contraction, and electromagnetic forces. Simulation results confirm that the radial stress within the coils remains compressive, effectively preventing layer separation, while the peak Von Mises stress remains below the material yield limits. Furthermore, thermal analysis indicates that the coil temperature stabilizes at approximately 2.66 K, ensuring a sufficient operating margin. The multi-physics analysis verifies that the magnet design satisfies all stringent electromagnetic, mechanical, and thermal requirements.