Implementation of RF modulation in Booster for mitigation of the collective effects in the transient process after the swap-out injection

On-axis swap-out injection is a promising injection scheme for the diraction-limited storage rings with small dynamic apertures. However, some previous studies have shown that the initial mismatch in the longitudinal phase space may lead to transverse collective instability before approaching the equilibrium state, especially in the high bunch charge situation. We present our study of mitigating the collective eects in the transient process after injecting beam into storage rings by implementing RF modulation technique in booster. Both bunch lengthening and the increase of energy spread could be observed in the extracted bunch from booster. The reduction of particle loss in the transient process after the swap-out injection is demonstrated via simulations.