Instabilities of high-order beam modes driven by space-charge coupling resonances - art. no. 084202

Space charge presents a fundamental limitation to high intensity circular a ccelerators. Its effects are especially important in the latest designs for high-intensity proton rings, which require beam losses much smaller than p resently achieved in existing facilities. It is therefore necessary to unde rstand the major space-charge effects which could lead to emittance growth and associated beam loss. In this paper, we explore the excitation of high- order collective beam modes and associated instabilities driven by space-ch arge coupling resonances. Such studies help us to understand energy exchang e and emittance growth driven by space-charge coupling. They also have dire ct application to the choice of a good working point in a high-intensity ma chine. The studies are performed using an earlier version of the Spallation Neutron Source lattice, which was used as a generic example of a circular machine. In this way, we explore the nature of the observed space-charge co upling effect and its applicability to high-intensity rings in general.