BEPC上离子引起的耦合束团不稳定性分析

Analysis of an Ion Induced Coupled Bunch Instability in BEPC

对在北京正负电子对撞机 (BEPC)上观测到的由离子引起的电子束二极耦合束团不稳定性的实验数据作了分析处理 ,给出了这种二极耦合束团不稳定性的边带 .首先用离子俘获的线性两束流理论定量计算了离子引起的二极耦合束团不稳定性发生的阈值束流流强和不稳定性的增长时间 ,然后用基于束流 -离子强弱作用模型的模拟程序跟踪了在实验情况下束流与离子的相互作用过程 ,跟踪结果成功地再现了离子引起的二极耦合束团不稳定性边带 。

An ion induced coupled bunch instability observed in the Beijing Electron Positron Collider (BEPC) is analyzed in the paper, with the given side band of the instability. A linear two beam theory of ion trapping is applied to calculate the threshold current and growth time of the instability. A simulation program based on the strong weak model is developed to track the interaction process between the beam and the ion cloud. The simulation results successfully reproduce the side band and give a reasonable growth time of the instability.