Comparative Analysis of Resistive Dipole Accelerator Magnets for a Muon Collider

This work focuses on the design of resistive dipole accelerator magnets for the Muon Collider accelerator under study in the frame of the International Muon Collider Cooperation (IMCC) and with the participation of the European Union (MuCol program). The design specifications require that these dipoles are subjected to very fast ramps, with ramp times in the range from 1 ms to 10 ms. This in turn results in the need for very high power, in the order of tens of GWs for the chain of Rapid Cycling Synchrotrons (RCS) to be realized. For the magnet design, three geometric configurations were considered and compared in this study, namely the hourglass magnet (previously considered in the US Muon Collider design study), the windowframe magnet and the H-type magnet. An optimization procedure was carried out to minimize the energy stored in the magnet, in order to reduce the energizing power during the fast ramps. The results found for the three considered configurations at different current densities are compared in the paper in terms of total stored energy, total losses during the operation current cycle and field quality. The H-type magnet is identified as a suitable configuration due to both low stored energy and low losses.