高功率O型慢波器件的纵向模式选择研究

利用传输线理论说明了由于慢波结构与其输入、输出端阻抗不匹配导致同一横模对应的不同纵模的形成;根据S参数方法，研究了过模慢波结构TM01模对应各纵模的频率、场分布和Q值，并分析了慢波结构周期数对纵模的数目、纵模间的频率间隔以及各纵模Q值的影响等.在此基础上提出在O型慢波器件中使用谐振腔，可减少慢波结构周期数，不但使器件结构更为紧凑，还可避免纵模竞争，从而提高器件效率、稳定产生微波频率. 关键词： 纵模选择 传输线理论 慢波结构 谐振腔 O型高功率慢波器件

Investigation on longitudinal mode selection in O-type HPM devices

The reason of the emergence of longitudinal modes in the single-mode slow-wave structure(SWS) is analyzed in terms of the transmission line theory,which proves that the occurrence of the longitudinal modes can be attributed to the unmatching between the impedance of the SWS and that of its input and output ends. With the method of S -parameter,the features,such as frequency,field distribution and the Q -factor of the longitudinal modes of TM 01 mode in the overmoded SWS are investigated,and the influence of the period-number of the SWS on the number,the frequency interval and the Q -factor of longitudinal modes are analyzed. It is proposed that the introduction of a well designed resonant cavity to O-type HPM devices can help to achieve the longitudinal mode selection and reduce the period-number of the SWS,which not only can make the devices more compact,but also can avoid the destructive competition between various longitudinal modes,therefore can enhance the efficiency and stabilize the frequency.