BEPCII是一个多束团、大流强的装置, 由于高频腔的高次模和电阻壁阻抗等因素,不可避免地会出现束流不稳定性.BEPCII中采用束流反馈系统来抑制束流不稳定性.横向束流反馈系统主要包括前端电子学、信号处理电子学、反馈器件和放大器等几个部分.梳状滤波器是信号处理电子学的重要部件,利用两根长短不同的电缆以及一个功分器和合成器构成了一种简单有效的梳状滤波器,其梳状深度达到-41dB,使用这种梳状滤波器的横向反馈系统成功地抑制了束流中出现的不稳定性.

The high beam current(0.9 A) and the large number of bunches(93 bunches) may cause coupled bunch instabilities (CBI) in BEPCII.Active feedback systems are required to suppress CBI.The BEPCII transverse feedback system mainly includes three parts that are the signal detection unit,the signal processing unit,and the kicker.The notch filter is an important part of the signal processing unit.In this paper a simple notch filter which is combined with two cables,a splitter and a combiner is introduced.And a-41 dB notch depth is achieved.Transverse feedback system with this notch filter succeeds in curing the instability of the beam.It is proved that the filter can satisfy the requirement of the BEPCII transverse feedback system.