W波段准光模式变换器的设计

准光模式变换器是大功率输出回旋管的关键部件.采用高转换效率的准光模式变换器可以横向输出电磁波,增大收集极的尺寸,提高回旋管的输出功率,提高整管效率.该文设计的回旋管内置准光模式变换器由Denisov辐射器天线和四个反射镜组成,输入频率为94GHz,模式为TE_6,2模.采用耦合波理论分析和优化了Denisov辐射器内的场分布,并根据矢量绕射理论编制数值模拟程序计算了各个反射镜上的场分布,其输出功率转换效率达97.2%.利用三维全波仿真软件feko6.0进行对比分析,最后加工所设计的结构并内置于回旋振荡管进行热测实验,结果表明其输出场分布与理论计算结果基本一致.

Design a Quasi-Optical Mode Converter for W Band Gyrotron

Quasi-optical mode convertor is an important component for a high-power gyrotron.The transverse area of collector in gyrotron can be increased and the wave beam can be separated from the electron beam with a high conversion efficiency quasi optical mode convertor.To improve the conversion efficiency of the whole gyrotron,a quasi optical mode convertor with small size must be used to high-efficiently convert the cavity mode to fundamental Gaussian beam.This paper presents a quasi-optical mode convertor for TE_6,2 94GHz gyrotron.The converter consists of a dimpled-wall Denisov launcher,a quasi-elliptical mirror,two parabolic mirrors and a plane mirror.The coupled-mode theory is used to analyze the operation of the pre-bunching waveguide launcher.The code of the vector diffraction theory is used to calculate the radiate fields of the mirrors.The efficiency of more than 97.2% is achieved for converting the rotating TE_6,2 mode at 94GHz into a fundamental Gaussian beam.Simulations with feko 6.0 are done to compare with the calculation result.The structures is fabricated and placed in the 94GHz gyrotron.Experimental measurements show that close agreement with theoretical predictions is obtained.