场分析法与阻抗叠加方法在速调管输出腔间隙阻抗计算中的应用

Application of field analysis method and impedance superposition method in the gap-impedance calculation of klystron output circuit

从分析速调管输出回路的电磁场分量入手,结合微波电路理论,提出了计算速调管输出回路间隙阻抗的场分析法。对于在谐振模式交叠频带上,群聚电子束电流同时与各模式的阻抗相作用,总阻抗是各模式阻抗的代数叠加的情况,提出了阻抗叠加方法。该方法原则上可求解任意给定间隙电阻所对应的间隙电抗值。计算表明,场分析法与等效间隙阻抗法计算结果最大相对误差为1.5%,阻抗叠加方法计算结果与冷测数据最大相对误差为10%。分析表明,多个谐振模式的引进是速调管输出腔加载滤波器展宽频带的物理实质。

A new method, the field analysis method is used to calculate the gap-impedance in a klystron output circuit based on the analysis of the electromagnetic field components and microwave circuit theory. The impedance superposition method is presented for an output cavity where several resonant modes overlap. The bunched electron beams will interact with all the exist- ing modes and the sum of the gap-impedance in each mode constitutes the overall gap-impedance in the output cavity. This princi- ple can also be used to calculate the imaginary part for a given real part of the gap-impedance. An example illustrates that the maximum resulting error between the field analysis method and the equivalent gap impedance method is less than 1.5%, and the maximum error between the mode overlapping method and the measurement data is 10%. Both theoretical analysis and calculation show that the essence of bandwidth expansion in a filter loaded klystron output cavity is the introduction of many resonant modes.