针对谐波回旋管互作用效率低的问题, 以自洽非线性理论为基本工具, 系统地分析了三个关键因素, 即互作用腔体长度(Q值)、电子注的横纵速度比和工作电压对二次谐波互作用系统性能的影响.研究发现当工作磁场选择在硬激发区时, 通过综合调节电子注的横纵速度比和工作电压能够获得较高的互作用效率.基于自洽非线性理论优化设计了一个W波段二次谐波回旋振荡器, 粒子模拟(PIC)结果显示当电子注速度离散３％, 工作电压37 kV, 电流4 A时, 输出效率达到了39.5%.

To solve the problem of low interaction efficiency of harmonic gyrotrons, self-consistent theory was used to investigate the dependence of the interaction efficiency on three critical factors; cavity length (quality factor), electronic beam’s velocity ratio and operating voltage. It was found that high efficiency can be achieved by adjusting beam voltage and velocity ratio when the working magnetic field was located at the hard excitation region. Based on the self-consistent nonlinear theory, a W band second harmonic gyrotron oscillator was optimized. Particle in cell computation showed that the efficiency was up to 39.5% when the beam voltage and current was 37kV and 4A, respectively, with velocity spread of 3%.