Suppression of Longitudinal Coupled-Bunch Instability by Decoupling Method

The decoupling method to suppress the longitudinal coupled-bunch instability in the UVSOR electron storage ring was tried. Synchrotron frequencies of individual bunches were spread by means of the modulation of the effective acceleration voltage in order to decouple these synchrotron oscillations. The instability is successfully damped by this method when the beam current is not high and the growth rate is moderate. The limitation of this method is not in the principle but in the maximum modulation index available in this experiment.