变周期慢波系统内同步问题的研究

Analysis of synchronization in the varying-period slow-wave structures

由于行波管的工作依赖于其慢波系统中的电子注与沿轴传输交变电磁场之间的相互作用而完成,而这样的相互作用要求沿轴传输的交变电磁场必须与电子注有着近乎同步的速度,所以慢波系统内的同步问题就成了研究行波管的一个很重要的问题.而变周期慢波系统是将一般慢波系统的周期进行变化而形成的,它可以比原周期慢波系统有着更宽的带宽,更高的互作用效率,还可以选择空间谐波.本文分析了变周期慢波系统内的空间谐波,提出了使慢波系统内的一次空间谐波一直与电子注同步所需要满足的原则,最后以变周期折叠波导为例,证明了这个原则.

To utilize the interaction between the field and the electron beam in a traveling wave tube （TWT）, the velocity of electrons and the longitudinal phase velocity of field should be made approximately equal. But when the electromagnetic energy increases, the electrons are slowed down and the synchronization condition is no longer satisfied in periodic structures. However, the varying-period slow-wave structure can be used to maintain the synchronization in the whole interaction section. This structure also has the advantages of space harmonic selectivity and wide bandwidth. The space harmonic in varying-period slow-wave structures is analyzed here. The synchronization condition of one space harmonic with the electron beam during the whole interaction process is presented in this paper. And the folded waveguide with varying period is analyzed as an example.