纵向束流反馈冲击器优化设计

Optimization design of a longitudinal kicker for a Beam Feedback System

纵向束流反馈冲击器是纵向束流反馈系统的关键部件之一。由于北京正负电子对撞机(BEPC)的高频频率为500 MHz,要求反馈系统的带宽不小于250 MHz。在清华大学加速器实验室研制的纵向束流反馈冲击器模型腔的基础上,该文利用MAFIA等电磁场微波模拟程序对其进行优化设计,通过优化冲击器脊波导的脊缝宽度和角宽度,使冲击器带宽从210 MHz增至260 MHz。使用微波矢量网络分析仪测量了改造后冲击器的阻抗、散射参数和高次模,并与优化计算做了比较。改造后冲击器的中心频率、带宽和分流阻抗均满足设计要求。文中还对冲击器的高次模进行了分析和测量。

The kicker is one of the key components in a longitudinal feedback system. A prototype cavity of a longitudinal feedback kicker was developed with a kicker bandwidth that had to be wider than 250 MHz to damp any coupled bunch modes in Accelerator Lab of Tsinghua University since the RF frequency of the driving accelerator was 500 MHz. The kicker cavity was modified with the MAFIA code to increase its bandwidth from 210 MHz to 260 MHz. Vector network analysis was used to measure the impedance and bandwidth of the modified kicker for comparison with simulation results, The central frequency, bandwidth, and shunt impedance of the modified kicker all achieved the design goals. Higher order modes in the kicker were also analyzed.