Feedback systems for FCC-ee

Abstract: In this paper, some preliminary considerations on the feedback systems for FCC-ee are developed. Bunch-by-bunch feedback systems have been designed in the last years for other e+/e- colliders like PEP-II, KEKB, DAFNE, SuperB and SuperKEKB. In all these cases, similar approaches have been implemented, even if some design variations have been suitable or necessary for different reasons. Bunch-by-bunch feedback systems are based on the concept that the barycenter of each bunch moves with harmonic motion around the equilibrium point in three planes (L, H, V). The feedback copes with the forcing excitation by producing damping correction for each individual bunch. This is possible managing every single bunch by a dedicated processing channel in real time. For FCC-ee the very high number of stored bunches requires much more power in terms of processing capability for the feedback systems. Ring length (100 Km) and very low fractional tunes must be also considered requiring for a more effective strategy in the feedback system design.