休斯型耦合腔慢波结构正向设计初步研究

Preliminary Study of Top-Down Design of Hughes Coupled-Cavity RF Structure

针对高效率耦合腔行波管提出一种正向设计的初步方法,可根据设计指标对其慢波结构进行快速的定量设计。其设计思想是在满足带宽内的注波互作用同步条件的基础上,尽可能提高总阻抗。为此提出"带宽相速差之比"参量来描述带宽与同步的关系,并以此参量和Curnow等效电路模型分析了休斯型耦合腔慢波结构的各个参量变化对带宽和总阻抗的影响情况,从而建立慢波结构的正向设计过程;使用这种设计方法,针对给定的Ka波段的耦合腔行波管参数指标进行快速设计,设计结果基本满足指标要求。

The preliminary top-down design method was developed to fast design the high efficiency,coupled-cavity RF structure,in accordance with the technical requirements of the cavity-coupled traveling wave tube（TWT）.The core idea is that the total impedance should be maximized in such a way that the synchronization conditions are satisfied,under which the beam-wave interaction occurs in the full range of the operating frequency.Here,an indicator,ratio of bandwidth-phase velocity,was defined to describe the relationship between the band width and synchronization.The impacts of the various factors of Hughes coupled-cavity RF structure on the band width and total impedance were evaluated,in terms of newly-defined,ratio of bandwidth-phase velocity and the Curnow equivalent circuit model.And the top-down design of the RF structures was done accordingly.A prototyped,Ka-band coupled-cavity RF structure was designed and fabricated.The tested results show that the newly-developed design method works pretty well.