通过将次谐波腔体等效为RLC 并联回路,求得了射频功率馈入腔体的耦合度公式, 分析了上海光源直线加速器次谐波腔输入耦合器的设计要点, 通过3维电磁计算软件CST的数值模拟方法对耦合器结构尺寸、耦合环的深度与方位、耦合度进行了模拟计算。介绍了对次谐波腔耦合器进行小信号测试的过程、腔体安装及在线调试的方法。

With its equivalent RLC circuit, the coupling factor of a sub-harmonic cavity as a function of the cavity’s parameters are derived. This paper presents the design points of the coupler, which is an important part of the sub-harmonic cavity working at 499.654 MHz in the linac of the Shanghai synchrotron radiation facility(SSRF).The structure, the depth into the cavity and the direction of the coupler have been optimized with the three-dimensional finite element method software CST, as well as the coupling factor of the cavity. The cavity has been tested at low RF level. The measurement agrees well with the design values. And some methods on installation and test are given.