Hi-Lumi LHC Twin-Aperture Orbit Correctors Magnet System Optimisation

The large hadron collider (LHC) upgrade, called high luminosity LHC (HL-LHC) is planned for the next decade. A wide range of magnets and new technologies are currently under development. One of these systems will be a set of twin-aperture beam orbit correctors positioned on the approaches to the ATLAS and CMS experiments. This twin-aperture magnet system comprising 16 magnets, approximately 2 m long, with large 105 mm clear aperture coils. Each aperture will independently deliver 5 T·m integral field, between apertures the field vectors are rotated by 90° from each other, individually powered, crosstalk between apertures is controlled to give good field quality independent of aperture powering status. This paper presents the sequence of magnet optimisations performed that determine optimal coil geometry for the canted cosine theta coil design, to achieve good field quality between the individually powered large apertures, quench optimization, integration of the magnet with the adjacent magnetic objects, and radiation hard robust design. Finally the design focuses on low system cost with minimal tooling.