High Gradient Nb3Sn Quadrupole Demonstrator MKQXF Engineering Design

The future upgrades of the CERN accelerator chain along with the future high-energy colliders, notably the future circular collider (FCC), will require high gradient quadrupoles. As part of the High Luminosity Large Hadron Collider (HL-LHC) project, the 11 T dipole was designed to be compatible with accelerator requirements and industrial production. It is based on the “pole-loading” concept. This allows shimming at the pole and uses the collars more efficiently for creating the coil prestress. MKQXF is a further application of the “pole-loading” concept for Nb₃Sn quadrupoles. The pole region of the coils is identical to the 11 T dipole and the collared coil is based on dipole-type collars. This concept can be extended to any length and applied on both 1-in-1 and 2-in-1 configurations. For benchmarking purposes and to compare with the present base-line design of the HL-LHC IR quadrupole MQXF, based on the bladder-and-key concept, this conceptual study was made with identical coils and quasi-identical magnetic characteristics. The design features 140 T/m gradient in 150 mm coil aperture. This paper describes the design concept of MKQXF and the multiphysics finite element model, including the end regions. The design is described and the optimized assembly parameters and the effect of the manufacturing tolerances are presented.