FCC-hh Conceptual Designs and Windability of the Main Quadrupoles

In the framework of a design study for a post-LHC 100 TeV circular hadron collider, namely FCC-hh, high-gradient Nb3Sn lattice quadrupoles were investigated, following closely the specifications from the optic layout of that machine. After several iterations, a baseline design of the main quadrupole was selected and, then, included in the FCC-hh Conceptual Design Report. The article deals with the preliminary results of the 3-D electromagnetic and mechanical conceptual design. The 3-D design of Nb3Sn coil ends is known to be a critical phase, especially for small apertures. To tackle the potential issues, 3-D 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.