高次模多注速调管同轴输出腔性能改进的研究

Study of the Performance Improvement on Coaxial Output Cavity for Higher-order Mode Multiple-beam Klystron

该文针对工作在TM310模的多注速调管同轴输出腔中工作模式的场分布均匀性、外观品质因数及其与邻近模式的频率间隔等问题进行了研究,提出了一种带有短路杆和金属环的多注速调管同轴输出腔结构。分析发现,适当设置短路杆和金属环不仅可以使外观品质因数降低,还可以改善工作模式的场分布;而且设置金属环还可以增大TM310模和邻近模式的频率间隔以实现抑制杂模。利用仿真软件对X波段的同轴输出腔进行了模拟计算,计算结果与理论分析一致。在此基础上加工了冷测模型,测试结果表明TM310模与邻近模式的频率间隔均达到了1.2 GHz以上,外观品质因数从507.4降至193.5,工作模式的场分布也变得均匀。

Three problems of the coaxial output cavity operating at TM310 mode for Multiple-Beam Klystron（MBK） are concerned： the field distribution symmetry,the external Q-factor of operating mode,and the frequency interval between operating mode and neighboring modes.In order to improve the performance of coaxial output cavity,a cavity with reentrant ring and short circuit pole is proposed.Setting the short circuit pole suitably can not only decrease external Q-factor,but also make field distribution uniform.Furthermore,inserting the reentrant ring can enlarge frequency interval between operating mode and neighboring modes to suppress the parasitic modes.The coaxial output cavity in X-band is modeled and simulated by CST-MWS.And then the actual output cavity is manufactured and tested.The tested frequency intervals between TM310 mode and neighboring modes are both enlarged to more than 1.2 GHz.The external Q-factor is diminished from 507.4 to 193.5.And the symmetry of the field distribution of TM310 mode is improved.