3D Mechanical Analysis of a High-Curvature Superconducting Dipole

The Superconducting Ion Gantry (SIG) project, developed in collaboration with INFN, CERN, CNAO, MedAustron and FEAC Engineering, aims to improve cancer treatment by creating compact and lightweight ion gantries. These systems allow for precise, non-coplanar irradiation while reducing damage to surrounding healthy tissues. A key element of this project is a 4 T curved superconducting dipole magnet, made with Nb-Ti Rutherford cables, featuring a 1.65 m curvature radius and an 80 mm aperture, designed for a 430 MeV/u carbon ion gantry. This study addresses the mechanical challenges of the magnet's curvature, maintained by two curved steel clamps, and the use of an indirect cooling system. To test the design and assembly process, a 30<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> demonstrator is being developed as a step toward the final 45<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> dipole. Building on previous 2D mechanical studies of the SIG curved dipole, this work presents a 3D FEM analysis of the magnet support structure. The vertical preload system aims to maximize the contact between the coil, collars, and yoke, evaluated through the percentage of elements in contact during assembly, cooldown, and energization. At the coil ends, the longitudinal preload system provides restraint and prevents additional movements during powering. All stresses remain within allowable limits, supporting the development of a design compatible with indirect cooling.