根据注-波互作用自洽非线性理论，编写了分析渐变复合腔的计算程序，通过该程序，获得了工作模式对为TE021-TE031的注-波互作用腔体和相关电磁参量的优化结果。应用粒子模拟软件对设计的复合腔进行了模拟，模拟与数值计算结果基本一致。根据计算结果研制了二次谐波回旋管,在加速电压57.5 kV、电流10 A下，测得其工作频率为94 GHz，输出模式为TE01，峰值功率和效率分别为156 kW和27.1%。计算、模拟和实验结果基本一致。

A code used to analyze beam-wave interaction in complex cavity is written based on the self-consistent nonlinear beam-wave interaction theory. The code is used to optimize cavity and electromagnetic parameters of a gradual transition complex cavity with second-harmonic waves of TE021-TE031 mode group. Simulations using the software Magic show a good agreement with calculations. Based on the calculations and simulations, a second-harmonics complex-cavity gyrotron is developed. Experiments show that the gyrotron delivers steadily peak power of 156 kW with an efficiency of 27.1% and output of TE01 mode at frequency 94 GHz, voltage 57.5 kV and current 10 A. Data of calculations and simulations are consistent with those from the experiments.