Mechanical Design of the Next European Dipole

The next european dipole (NED) Consortium is working to develop the technology of high field, dipole magnets for a future luminosity upgrade of the LHC at CERN. The proposed magnet will be a large aperture (88 mm), high field (15 T) superconducting dipole magnet using Nb₃Sn Rutherford cable and a wind-and-react manufacturing scheme. The magnet geometry (cosine-theta), scale and forces present real challenges for the design of the mechanical structure and the magnet assembly methods. This paper reports on the mechanical design studies carried out during the first phase of the NED project (2004 to 2007). This paper describes the development of a full 2-D mechanical Finite Element model of the dipole magnet including the superconducting coil, the collars, the iron yoke structure and the outer support cylinder. The model has been qualified and used to study the stress levels in the coil at assembly, cooldown and powering. Due to the strain sensitivity of Nb₃Sn conductors, a primary objective has been to limit the compressive stress in the superconducting cable to 150 MPa at full field.