标题： 高阶模式腔体束长监测器的设计与仿真 显示英文标题

标题： Design and Simulation of a high order mode cavity bunch length monitor

摘要： 一种基于高阶模腔的新型束团长度测量方法被提出。 将谐波腔工作在TM0n0模式，以便选择其半径，从而突破束流管道半径的限制。 设计了一种用于正电子源直线加速器的双腔束团长度监测器。 讨论了针对不同束团时间结构的运行频率选择，并推导出了束团长度的计算公式。 基础谐波腔在2.856 GHz频率下谐振，模式为TM010。 第五谐波腔在14.28 GHz频率下谐振（即直线加速器基础频率2.856 GHz的第五次谐波），模式为TM020，可以提供更大的半径。 每个腔体都配备了一个滤波器以抑制不需要的信号。 在CST Particle Studio中进行了仿真测量，束流为100-300mA，束团长度为5-10ps，计算结果表明具有较高的精度（优于3%）。 讨论了几个案例。 显示英文摘要

摘要： A new bunch length measurement method based on high order mode cavity was proposed. Operating the harmonic cavity at mode TM0n0 so that its radius could be chosen, in order to break the limitation of beam pipe radius. A two-cavity bunch length monitor for linac of positron source was designed. Operating frequency selection for different bunch time structure was discussed and calculation formula of bunch length was deducted. Fundamental harmonic cavity resonates at 2.856 GHz with mode TM010. Fifth harmonic cavity resonates at 14.28 GHz (fifth harmonic of the linac fundamental frequency 2.856 GHz) with mode TM020, which could provide larger radius. Each cavity equipped with a filter to suppress unwanted signal. A simulation measurement was conducted in CST Particle Studio for beam current from 100-300mA, bunch length from 5-10ps, calculation results shows a fairly high accuracy (better than 3%). Several cases were discussed.