140 GHz回旋管高转换效率准光模式变换器设计研究

On the design of high conversion efficiency quasi-optical mode converter for 140 GHz high-power gyrotron applications

成功实现高转换效率的140 GHz TE22,6准光模式变换器原型设计。基于周期微扰原理设计Denisov辐射器,实现低边缘绕射的初级出射波束。针对三镜面光路系统,采用全矢物理光学积分作为主要计算手段,围绕主极化场分量进行三级相位修正面迭代优化,实现高出射高斯纯度的模式场转换,其中一级镜的修正有效改善了辐射器出射的不理想性。基于全矢数值仿真确认,相比原二次曲面原型设计,相位修正后的变换器系统的出射高斯纯度从92.7%提高到99.6%,结合98.8%以上的功率传递效率,实现了性能优越的高阶回旋管准光模式变换器原型设计。

A high conversion efficiency quasi-optical mode converter prototype is designed for 140 GHz TE_(22,6)ap⁃plications.The Denisov launcher is designed based on the periodic perturbation concept,leading to primary radia⁃tion field with low edge diffraction.Full-vector physical optics integration solver is used to model and analyze the 3-mirror system.And the 3-mirror iterative phase correction is applied based on the co-polarization field compo⁃nent,so as to achieve high-quality mode conversion.Specifically,the correction of the 1st mirror sufficiently re⁃fines the non-ideal radiated fields from the launcher.It is then validated by numerical investigations that,compar⁃ing to the original quaritic mirrors,the phase-shaped mirror system leads to excellent conversion performance.The Gaussian content(ηv)of the output fields rises from 92.7%to 99.6%,while the power transmission efficien⁃cy(ηp)reaches 98.8%.