Topology Optimization of a 10 T, 52 cm bore stellarator magnet structure

The performance of high-field magnets is increasingly constrained not by the limits of High-Temperature Superconducting materials, but by the structural systems needed to withstand the intense Electro-Magnetic forces they produce. In response to this challenge, this work presents a design-driven methodology for optimizing the reinforcement structures of 52 cm bore wide HTS magnets under development at Renaissance Fusion, aimed at achieving magnetic fields up to 10 T on the plasma axis. A custom Topology Optimization tool, based on the Solid Isotropic Material Penalization method and implemented entirely in PyMAPDL, was employed to guide the mechanical design of the magnet reinforcements. Starting from a large design domain ( ∼ 11.3 tons per sector), Topology Optimization with varying volume fractions produced lightweight structures, down to 3.93 tons, that meet strict mechanical constraints on magnet displacement ( < 1 mm), magnet strain ( < 0.5%) and global stress ( < 800 MPa). Then, a second optimization stage using extrusion constraints methodologies was employed to further optimize the structure while ensuring manufacturability. Recurring features from these runs informed the development of a parametric model, enabling further refinement and a final mass of 1.20 t. The final structure, segmented into sub-components for a feasible assembly procedure, retained the required mechanical performance while ensuring ease of manufacturing using conventional processes. This magnet design demonstrate the applicability and benefits of our multi-stage constrained topology optimization method for advancing the structural design of high-field and compact stellarators.