Simulation Study of the Beam Loading Effects During the Bunch Merging in HIAF-BRing

In the booster ring (BRing) of the High Intensity heavy-ion Accelerator Facility (HIAF), the multi-bunch should be merged into single bunch after the acceleration. To study the influence of the beam loading effects during the bunch merging, the simulations of particle tracking with ²³⁸U³⁵⁺ beam are carried out. According to the simulation results, during the bunching merging, the beam loading effects can result in the growth of the momentum spread and the bunch length as well as the oscillation of the bunch length and the bunch center. The potential well distortion induced by the wake voltage and wake field coupling during the bunch merging are the reasons why the bunch center oscillates and the emittance of the beam grows. To reduce the influence of the beam loading effects, the multi-harmonic feed-forward system is employed to compensate the wake voltage. With the feed-forward system, the beam loading effects can be compensated during the bunching merging. The feed-forward system is able to guarantee the high quality of the beam for extraction in the BRing. The frequency range to be covered and the largest wake voltage to be compensated by the feed-forward system are determined according to the simulation results.