FCC-hh conceptual designs and windability of the Main Quadrupoles

In the framework of a design study for a post-LHC 100 TeV cir-cular hadron collider, namely FCC-hh, high gradient Nb3Sn lat-tice quadrupoles were investigated, following closely the specifi-cations from the optic layout of that machine. After several iter-ations, a baseline design of the Main Quadrupole (MQ) was se-lected and, then, included in the FCC-hh Conceptual Design Re-port. The paper deals with the preliminary results of the 3D elec-tromagnetic and mechanical conceptual design. The 3D design of Nb3Sn coil ends is known to be a critical phase, especially for small apertures. To tackle the potential issues, 3D electromagnetic design was first carried out, taking into account the field quality constraints, the field margins in critical areas, and the windability of the coil ends. Then, winding trials with actual cables were performed, to help selecting designs and identifying critical geometrical parameters.