双频回旋管内置准光模式变换器设计

Design of quasi-optical mode converter for dual-frequency gyrotron

摘要: 回旋管一般使用准光模式变换器实现高阶腔体模式到高斯波束的转换。结合标量衍射理论、KS迭代算法、几何光学、最小均方法等方法设计了工作频率为140 GHz（TE_{24, 9}）和105 GHz（TE_{18, 7}）的双频准光模式变换器。仿真结果显示所设计的准光模式变换器工作频率为140 GHz（TE_{24, 9}）时能量传输效率99.0%、高斯含量99.7%，工作频率为105 GHz（TE_{18, 7}）时能量传输效率97.3%、高斯含量98.0%。能够满足MW级双频回旋管的应用需求。

Abstract: Quasi-optical mode converters are usually used in gyrotrons to realize the conversion of high-order cavity mode to Gaussian beam. Using the scalar diffraction theory, the K-S phase-correcting optimization iterative algorithm Geometrical Optics and the least mean square(LMS) algorithm, this paper designs a dual-frequency quasi-optical mode converter with operating frequency of 105 GHz (TE_18,7) and 140 GHz (TE_24,9). According to the simulations results, the conversion efficiencies are 97.3% at 105 GHz and 99.0% at 140 GHz. And the Gaussian contents of the output beam on the window surface are 98.0% at 105 GHz and 99.7% at 140 GHz. This high efficiency dual-frequency quasi-optical mode converter can be used in a MW dual-frequency gyrotron.