BEPCⅡ对撞点束流轨道反馈系统设计

摘要

This paper describes the design of IP orbit feedback system for BEPCⅡ. In the BEPCⅡ the electron and positron beams circulate in the separate rings and collide only at the southern interaction point (IP) with a crossing angle, thus an IP orbit feedback system based on the beam-beam deflection technique is necessary for maintaining an optimum beam collision condition at the IP. Moreover, in order to measure the positions of both positron and electron in the IP at the same time, two special BPMs with 8-button electrodes will be installed at the both side of interaction point. The working principle of the special BPM and the simulation results with finite element method are also described in this paper.%介绍了BEPCⅡ(北京正负电子对撞机二期工程)对撞点束流轨道反馈系统的设计.由于BEPCⅡ将采用双环、多束团、交叉角对撞,并且多种原因会使束流处于非最佳对撞状态甚至无法对撞,因此一套基于束-束偏转技术的对撞点束流反馈系统的建立,以使得对撞机保持在最佳对撞状态是非常必要的.此外,为了同时测量对撞点处正、负电子束的位置,两套带有8电极的特殊束流位置探测器(BPM)将安装在对撞点两侧.8电极BPM的工作原理以及采用有限元法进行模拟计算的结果在文章中也进行了介绍.