独立调谐微波电子枪耦合结构的仿真及测试（英）

精确的功率耦合结构设计是保证高品质束流的关键。为确保系统实际运行中的独立调谐微波电子枪耦合性能满足设计要求，对其进行了仿真与测试。首先应用电磁仿真软件CST对电子枪进行了频域和本征模式的仿真计算，两种方法计算结果吻合，谐振频率分别为2 856.10 MHz和2 856.07 MHz，耦合系数分别为1.624和1.620。同时，对已经安装在加速器上实际运行的电子枪分别采用反射系数法与腔体损耗法进行了耦合性能的测试。单点的反射系数法测得耦合系数为1.78，谐振频率为2 855.77 MHz。在此谐振点上，结合反射系数法和腔体损耗法进行多点拟合，测得耦合系数为1.785。结果表明，仿真计算结果与实际测试的结果基本相符。

Coupler simulation and test of an independently tunable RF gun

Accurate power coupler design is one of the key points to ensure high quality for RF gun used in FEL facility. In order to meet the design requirements of the RF gun, the simulation and test of coupling performance for the independent tunable RF gun applied in the HUST FEL-THz were conducted. First of all, the electromagnetic simulation software CST was used to calculate the RF gun both in frequency domain and eigenmode, and the results of these two methods are consistent with each other. The resonant frequencies are 2856.10 MHz and 2856.07 MHz respectively, while the coupling coefficients are 1.624 and 1.620. Additionally, the coupling performance of the RF gun which had been installed on the accelerator was measured by reflection coefficient method and cavity loss method respectively. The coupling coefficient of the 2nd cell is 1.78 and the resonant frequency is 2 855.77 MHz based on the former method on single point. Combined with both methods on this resonance point, the coupling coefficient is 1.785 by means of multipoint fitting. The results show that good agreements are achieved between simulations and measurements.