CERN Super Proton Synchrotron and an alternative design as prebooster ring for the future circular collider e plus e- injector complex

The Future Circular Collider (FCC) e+e- injector complex needs to produce and transport highintensity e+ and e- beams at a fast repetition rate for topping up at collision energy. Two options are considered for a preaccelerator ring, to be used for an intermediate accumulation and acceleration before the bunches are transferred to the high-energy booster. One option is a slightly modified Super Proton Synchrotron (SPS), and the other is designing a new ring. We explore the needs and parameters of the existing SPS as prebooster ring and also develop a conceptual design of an alternative accelerator ring. After establishing the basic parameters, we describe the optics design and layout and discuss the single-particle linear and nonlinear dynamics optimization, including magnetic and alignment errors. In addition, we present synchrotron radiation power studies and analytical estimates of various collective effects for both prebooster ring design options, including space charge, intrabeam scattering, longitudinal microwave instability, transverse mode coupling instability, ion effects, electron cloud, and coherent synchrotron radiation.