Preliminary 3D Mechanical Design of the FCC-hh Main Quadrupoles

For the Future Circular Collider hadron-hadron (FCC-hh), a 100 TeV post Large Hadron collider machine, 750 main quadrupoles with a 360 T/m gradient over a magnetic length of 7 m are required. They consist of a double aperture based on a laminated collar structure similar to the LHC MQ technology. In this paper, a preliminary 3D finite element analysis is performed to evaluate the stresses and strains of the complete magnet structure, with particular emphasis on maintaining coil pre-stress at the pole-coil interfaces under operation. Numerical results during preload, cool-down, and energization are presented in detail and discussed. The peak stress is of the order of 160 MPa in the Nb ₃ Sn coil with a localized gap of less than 6 μm at the coil-pole interface under nominal operation. The stress in the mechanical structure is bearable with only high stress values confined to very small areas.