设计了速调管的单间隙和双间隙圆柱同轴腔高阶TM310模式输出回路。为降低外输出腔的外观品质因数和增加腔内工作模式电磁场的均匀性，采用了在输出孔处腔内侧位置设置轴向短路金属线的措施。由等效电路理论分别计算了它们加载空矩形波导TE10基模时，腔内漂移管中心位置处的等效间隙阻抗及对应的输出带宽。计算模拟发现，与单间隙腔相比，双间隙腔具有较大的间隙阻抗及带宽。

The output circuit of high-order TM310 mode in single- and double-gap cylindrical coaxial cavities of klystron is designed. The gap impedances at the drift tube centers and corresponding output bandwidths are calculated, simulated and compared according to the equivalent circuit theory when the cavities are loaded with TE10 mode in empty rectangular waveguide. It is found that, double gap cavities have larger gap impedances and bandwidths than those of single gap cavities. By means of setting copper short circuit line in the inner side of output holes, the external quality factor is reduced and the mode uniformity in cavities is increased. This output circuit is suitable for high frequency, high power and narrowband klystrons. The research results are significant to output circuit design of high-order TM mode coaxial cavities of klystrons.