70GHz二次谐波倍频回旋速调管研究

Design of a 70GHz second-harmonic frequency-doubling gyroklystron

对70 GHz二次谐波倍频回旋速调管高频结构和电子与波互作用进行了研究。研究了TE02模腔体绕射品质因数及模式转化,解决了二次谐波倍频回旋速调管漂移段不能截止70 GHz的TE01模而引起的腔体间高频串扰的问题。分析了注电流、输入功率、电子横纵速度比和电子注引导中心半径等参数对输出功率、增益和效率的影响。针对二次谐波回旋速调管放大器工作频带窄、效率低,进行了高频结构优化设计,显著地展宽了工作频带,提高了互作用效率。在理论分析和高频计算的基础上,建立了注-波互作用PIC(粒子模拟)模型,进行了粒子模拟计算和优化,得到了70 GHz的二次谐波倍频四腔回旋速调管放大器设计方案。粒子模拟结果表明:在工作电压70 kV,注电流13 A,电子注横向速度与纵向速度比为1.5时,中心频率69.81GHz输出功率256 kW,带宽160 MHz,电子效率28%,饱和增益大于44 dB。

A 70 GHz second-harmonic frequency-doubling gyroklystron with four cavities has been studied. The input cavity operates in the fundamental harmonic TE02 mode at 35 GHz and the other cavities operate in the second harmonic TE-2 mode at 70 GHz. The quality factor and mode conversion of the bunching cavities were studied in detail with field matching analysis to reduce the RF crosstalk of the 70 GHz TE0t mode between cavities. And the RF circuit was designed and optimized to enhance operating bandwidth and electron efficiency. And then a 70 GHz second-harmonic frequency-doubling gyroklystron was designed. 256 kW output power, 44 dB saturation gain, 28% electron efficiency with about 160 MHz instantaneous bandwidth were obtained by PIC simulation at 70 kV, 13 A electron beam. The instantaneous bandwidth and electron efficiency are much better than the results of a reported 70 GHz second-harmonic frequency-doubling gyroklystron.