三反射镜准光模式变换器的设计与模拟

本文设计了一种用于W 波段边廊模回旋振荡管的三反射镜准光模式变换器。该模式变换器由一个Vlasov 型螺旋 切口辐射器和三面聚焦反射镜构成,可以将回旋管输出的高阶模式高效地转换为准高斯模式。根据矢量绕射理论和物理 光学法编写了模拟仿真程序,并对辐射器和反射镜的空间辐射场进行了计算、优化和分析。计算结果表明：输出波束中 高斯基模的标量相关系数为97.9%,矢量相关系数为95.9%,转换效率达到了81.5%。     

94 GHz回旋管准光模式变换器的数值模拟

对回旋管内置准光模式变换器进行了理论研究和数值模拟。基于几何光学理论和矢量绕射理论,编制了模拟电磁场行为的分析和优化程序,采用Vlasov辐射器和准光反射器实现了线极化准高斯模HE11。结果表明:在一级反射镜下的转换效率为88.3%,增加反射镜级数会降低转换效率。     

426GHz回旋管准光模式变换器

采用几何光学模型研究并设计了一个由Vlasov矩形开口辐射器和两级曲面反射器组成的太赫兹回旋管准光模式变换器。利用几何光学理论对Vlasov型准光模式变换器进行了初步设计,采用矢量绕射理论对准光模式变换器进行了详细的分析并编写相应程序,最后结合具体设计参数,得到工作模式在模式变换器中的变换过程。模拟结果表明,太赫兹回旋管中的TE0.6模式在输出窗处被转换为能量集中的准Gauss波束,其效率为89．0％。     

W波段回旋管准光模式变换器的研究

该文对W波段TE₆₂模回旋管准光模式变换器的辐射器和镜面系统进行了设计与实验验证。基于耦合模理论,采用两级微扰对辐射器进行了设计,获得了圆波导内壁上的类高斯束斑的场分布;基于惠更斯原理的矢量衍射积分理论,对准光模式变换器的镜面系统进行了优化设计,模拟与计算结果表明准光模式变换器的模式变换效率为92.3%。最后,通过热测实验,验证了输出模式为W波段类高斯模式。     

一种准光模式变换器的设计和实验

准光模式变换器是实现高功率回旋管高效输出的重要部件。该文针对140 GHz, TE_28,8模回旋振荡管研制,开展以Denisov型辐射器和3个准光镜面构成的准光模式变换器设计与实验研究。利用标量衍射法优化辐射器辐射口径处的场分布,其与理想高斯场之间的矢量相关性为96.2%;基于几何光学和高斯波束匹配方法设计了聚焦镜面与波束整形镜面,采用3维全波分析软件Surf3D获得各个镜面上及输出窗处的场分布,对所设计的镜面系统进行了仿真验证,在输出窗处获得了高斯模式含量为96.67%的输出波束,整个模式变换器的功率转换效率为93.98%。以自行研制的TE_28,8模激励器作为准光模式变换器的输入,通过对模式变换器转换性能仿真结果验证,在严格控制加工精度及装配和实验过程的基础上,完成了准光模式变换器转换性能的冷测实验。实验结果表明,设计和实验具有合理的一致性,可以作为准光模式变换器工程应用设计和验证手段。     

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.     

回旋管准光辐射器研究与设计

准光辐射器是高功率回旋管准光模式变换器的重要组成部分.采用几何光学理论分析圆波导准光辐射器,根据高斯波束(TEM00模)在辐射器切口处形成的原因,利用耦合波理论设计波纹波导准光辐射器.通过编写程序并进行数值优化完成140 GHz、TE28,8模式回旋管波纹波导准光辐射器的设计,结果表明波纹波导辐射器的总长度仅为205.2 mm,切口长度为47.2 mm,在辐射器螺旋切口Brillouin区内高斯模式标量相关系数大于98%.本文所用的方法也可用于其它频率和模式的回旋管准光辐射器设计.     

回旋管准光辐射器研究与设计

准光辐射器是高功率回旋管准光模式变换器的重要组成部分.本文首先采用几何光学理论分析圆波导准光辐射器,然后根据高斯波束(TEM00模)在辐射器切口处形成的原因,采用耦合波理论设计波纹波导准光辐射器.通过编写程序并进行数值优化完成140GHz,TE28,8模式回旋管波纹波导准光辐射器的设计,结果表明波纹波导辐射器的总长度仅为205.2mm,切口长度为47.2mm,在辐射器螺旋切口Brillouin区内高斯模式标量相关系数大于98%.本文所用的方法也可用于其它频率和模式的回旋管准光辐射器设计.     

170 GHz回旋管准光模式变换器的设计

针对170 GHz回旋管研究,设计了一种高效Denisov准光模式变换器,该回旋管工作在模式。模式变换器由微扰结构的辐射器和镜面系统组成。基于耦合模理论和矢量绕射理论,研究了两级微扰辐射器,优化设计了镜面系统。仿真结果显示,模式转换为高斯光束,其输出功率转换效率为93.7%。     

94GHzTE6,2模内置准光模式变换器

提出了可应用于94 GHz回旋管内部的TE6,2准光模式变换器.根据几何光学和矢量绕射理论编制了模拟其电磁行为的分析和优化程序.根据几何光学原理,设计了该模式变换器的初步结构参数,然后利用该优化程序获得了最优化的相关参数.优化结果表明,在94 GHz,该准光变换器功率转换效率约为85%,转换所得波束高斯含量高于70%.     

94GHz二次谐波回旋管波纹波导模式转换

在耦合波理论的基础上,详细讨论了3mm二次谐波渐变复合腔回旋管内置TE03—TE02—TE01模式转换器,并使模式转换器兼作回旋管的收集极.采用波纹波导结构和不同的相位重匹配技术进行优化分析,得到了可靠的最优几何参量.以此结果设计出了紧凑、高效的94GH z波纹波导模式转换器,并在回旋管的热测实验中测出模式样图.     

Calculation of Radiation from a Helically Cut Waveguide for a Gyrotron Mode Converter in the Quasi-Optical Approximation

We present results of calculations of the radiation from a helically cut waveguide launcher, a so-called Vlasov launcher, which is commonly used either internal or external to a gyrotron for purposes of mode conversion. A gyrotron internal mode converter consists of such a launcher that radiates the waveguide mode as a nearly Gaussian beam in free space followed by a set of mirrors to focus and direct the radiation. The radiation from the launcher is first calculated using a geometric optics representation of the waveguide mode. Then the radiation is calculated in the quasi-optical limit, including diffraction. These analytic results are compared to a rigorous calculation using the computer code SURF3D, which uses an electric field integral equation (EFIE) approach. Good agreement is obtained between the quasi-optical theory and the SURF3D calculation. The present results provide new insights into the accuracy of the quasi-optical theory and may be useful for the design and improvement of Vlasov-type mode converters.     

96GHz边廊模Denisov辐射器

介绍了采用Denisov辐射器将96 GHz边廊模式信号转换为高斯波束的设计、仿真及测试结果.基于耦合波理论给出Denisov辐射器的设计方法.根据96 GHz TE_(6,2)模式Denisov准光模式转换器结构布局的要求,优化得到Denisov辐射器,输入半径6.4 mm,长52 mm,辐射器切割边缘电流幅值为汇聚中心点的10%,输出准高斯能量转换效率达96.51%.由其组成的准光模式转换器冷测输出高斯波束束腰直径22.4 mm,矢量转换效率大于95%.     

Quansi-optical mode converter for Ka-band application on a gyrotron

A series of electron cyclotron masers (ECMs) has been designed and successfully operated in the frequency range of 6 to 200 GHz over the past 10 years at Strathclyde University. The current Mk. VI ECM operated between 35–200 GHz, the TE _{0 1} ⁰ mode (35.2 GHz) being the lowest order cavity mode excited. Investigation of this ECM and quasi-optical converter combination was made to establish to what extent a Gaussian beam could be produced from the TE _{0 1} ⁰ gyrotron cavity mode. An antenna of the Vlasov (step-cut radiator) configuration was chosen and successfully developed in a series of low-power experiments up to the W-band frequency regime. The low-power experiments demonstrated that such an antenna system could be constructed and operated in the K_a-band frequency region without resorting to high precision quasi-optical components. The final version of the quasi-optical antenna was externally coupled to the output window of the maser and a plane polarized pencil beam was successfully obtained from the combined maser/Vlasov antenna mode converter. A theoretical model involving a single TE _0n ⁰ input mode was chosen to analyse the output beam characteristics from the Vlasov antenna system. Comparison was made between the single mode theoretical model and the experimental results obtained from the maser.     

An improved design for quasi-optical mode conversion of whispering gallery mode gyrotron radiation

Results are reported of a theoretical and experimental investigation of a quasi-optical mode converter for the transformation of whispering gallery mode gyrotron output into a linearly polarized Gaussian like beam. The mode converter consists of a helically cut waveguide launcher, similar to that originally proposed by Vlasovet al, followed by a focusing mirror. Theoretical results using aperture field methods indicate that the length of the waveguide launcher is of critical importance in providing a confined radiation pattern. Experimental results on the radiation pattern were obtained for several launcher lengths using a 0.6 MW, 149 GHz pulsed gyrotron operating in the TE_16,2 mode. Radiation pattern results for the optimum launcher length agree well with theoretical calculations using the Stratton-Chu aperture radiation theory for unperturbed waveguide modes. A mirror focusing in the azimuthal direction was designed by a geometrical optics approach to focus the radiation coming from the launcher. Good focusing with 91.4% efficiency (power in the focused beam divided by gyrotron power) was found experimentally using the combined launcher and mirror with the pulsed gyrotron. These results indicate that quasi-optical antennas are useful for transforming high order, high frequency gyrotron modes into directed beams in free space.     

太赫兹宽带Denisov型准光模式变换器的设计分析

研究并设计了一种具有宽频带工作能力的太赫兹准光模式变换器。该准光模式变换器采用具有高效率特性的Denisov 辐射器,工作在TE_6,2模式,用于实现回旋管内的模式变换。由于Denisov 辐射器的参数是影响准光模式变换器宽带性能的主要因素,因此通过对辐射器参数的优化设计,达到增大模式变换器带宽的效果。使用自主开发的准光学模拟程序进行仿真,模式变换器中心频率为94 GHz,带宽达2 GHz。