基于射频偏转腔的束团长度测量系统

本文建立了基于偏转腔的电子束团长度测量系统的模型，揭示了束流和偏转腔参数对测量结果的影响机制，给出了一种束团长度的计算方法。用三维仿真软件CST对腔体建模，得到了最优的单腔腔体尺寸、最优的耦合器尺寸和工作模式场分布，对应的偏转腔系统时间分辨率为182 fs，满足设计要求。用粒子跟踪软件Parmela进行束流动力学模拟，阐明了下游荧光屏上出现束团横向偏移的原因，并验证了理论结果的正确性。

Bunch Length Diagnostic System Based on RF Deflecting Cavity

In this paper, a bunch length diagnostic model based on RF deflecting cavity, which illustrated the mechanism of how the parameters of incident beam and cavity affect the measurement results, was established, and a bunch length calculation method was proposed. The cavity was modeled by 3D simulation software CST, and the most optimal one-cell cavity size, coupler size and working mode field distribution were obtained. The corresponding time resolution of the deflecting cavity system is 182 fs, which satisfies the design requirement. The beam dynamics simulation was carried out by particle tracking software Parmela, the reason for the transverse deviation of the bunch on the downstream screen was given, and the correctness of the theoretical result was verified.