Yannis Papaphilippou

Longitudinally Variable Field Dipole Design Using Permanent Magnets For CLIC Damping Rings

The latest CLIC damping ring lattice is based on magnets with longitudinally variable dipole fields in order to achieve ultralow beam emittance while keeping the ring circumference small. These magnets need to provide a focusing gradient of 11 T/m as well. The good field region radius is 5 mm. The field harmonics shall be in the order of 1E-4 of the main one. Since only a small variation of the field is requested, permanent magnets are the most cost-effective solution. Beam dynamics calculations have provided idealized field profiles, and magnetic calculations have been performed to check their feasibility. FEM electromagnetic computations are complicated because the cross-section of the magnet is not constant. Therefore, iron poles cannot be modeled by extrusion, and only 3-D computations are meaningful. Finally, this paper shows that small variations of field strength are possible by using movable parts

JACoW : SPS Studies in Preparation for the Crab Cavity Experiment

A local Crab Cavity (CC) scheme will recover head-on collisions at the Interaction Points (IPs) of the High Luminosity LHC (HL-LHC), which aims to increase the LHC luminosity to L ∼ 5 · 1034 cm−2 · s−1. The first time that CC will ever be tested with proton beams will be in 2018 in the SPS machine. The available dedicated Machine Development (MD) time after the installation of the cavities will be limited and therefore good preparation is essential in order to ensure that the MDs are as efficient as possible. This paper presents the simulations and experimental studies performed in preparation for the future MDs and discusses the next steps.