准光模式变换器研究与设计

Research and design of quasi-optical mode converter

研究了将回旋管及其他高功率微波器件的振荡输出模式转换成准高斯波束的准光模式变换器,实现了准高斯模TEM00的横向输出。利用几何光学分析了模式在波导中的传播,进一步分析了伏拉索夫(Vlasov)辐射器的工作机理,运用矢量绕射理论计算出辐射场;通过编程设计了将94GHz、模式为TE62的毫米波转化为准高斯波束的准光模式变换器。结果表明:通过设计Vlasov辐射器和两级反射镜,可以在窗口处得到准高斯波束,整个系统的功率效率达到87.5%。

This paper presents a quasi-optical mode converter which can convert the output mode of gyrotrons and other high-power microwave oscillators into quasi-Gaussian beam, aiming to achieve transverse output of quasi-Gaussian beam TEM00 mode. First, we analyze mode propagation in the waveguide and the working mechanism of the Vlasov launcher. Then the radia- tion fields are calculated using vector diffraction theory. At last a quasi-optical mode converter is designed to convert the 94 GHz, TE62 mode millimeter wave into quasi-Gaussian beam with programming method. The results prove that quasi-Gaussian mode can be obtained at the output window with a simple Vlasov launcher and two mirrors, and the power transmission efficiency of the quasi-optical mode converter reaches to 87.5 %.