Beam transverse stability in the CLIC combiner rings

The Compact Linear Collider (CLIC) RF power source is based on a new scheme of electron pulse compression and bunch frequency multiplication. In this scheme the drive beam time structure is obtained by the combination of electron bunch trains in isochronous rings using RF deflectors. One of the potential problems is the drive beam transverse stability in the rings, arising from beam resonant excitation of the electric field in the RF deflectors. In this paper numerical simulations are used to evaluate the effect and to show that the instability can be minimised by a proper choice of the tune of the ring, and of the parameters of the deflector and of the injection region lattice.