Measurement of the electric field pattern of a Fabry-Perot resonator used in quasi-optical gyrotrons

The field pattern of the resonator used in a quasi-optical gyrotron operating in the millimetre wave range is measured. Two resonators are studied: one composed of a spherical mirror and an ellipsoidal grating and the other symmetric using two mirrors with annular slots. The measurements indicate that the electric field distribution is gaussian, in spite of the complex geometry of the resonator, and thus provide an experimental basis for the assumption often used to compute the efficiency of quasi-optical gyrotrons.     

On the design of open resonators for quasi-optical gyrotrons

In the design of a 120 GHz 200 kW quasi-optical gyrotron, we have analyzed the influence of the open resonator geometry (two circular mirrors facing one another) on the electronic efficiency, the ohmic losses, the output coupling and the multimode behavior. The method we have used to optimized the resonator design will be presented. Mode selectivity is improved by using a resonator formed by two mirrors each of which has a central step. Numerical simulations show that single mode operation can also be attained in the more favorable situation of a magnetic field having a positive taper over the interaction region.     

高功率回旋振荡管Denisov型辐射器的研究

研究了一种用于高功率回旋振荡管准光模式变换系统的高效率Denisov型辐射器. 基于Bessel函数的积分展开及几何光学理论,系统地分析了圆波导中电磁波的传播过程及Denisov型辐射器降低衍射损耗的机理;分析了在圆波导内壁上工作模式与耦合模式叠加形成准高斯型场分布的过程. 从Bessel函数导数的本征值出发,给出了不同工作模式在Denisov型辐射器预聚束波导段选择目标耦合模式的一种普适方法,同时给出了Denisov型辐射器的设计方法. 依据上述理论分析编写了计算程序,并对一支140 GHz,工作模式为TE_28,8,1 MW长脉冲回旋振荡管进行了对比验证,计算结果与文献报道的结果具有很好的一致性.关键词：回旋管准光辐射器耦合模理论模式变换     

准光模式变换器研究与设计

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94 GHz、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%。     

高阶不对称体模回旋管Denisov型准光模式变换器（英）

详细研究了Denisov型准光模式变换器的原理和设计方法。应用几何光学理论对Denisov型开口辐射器的工作过程进行了分析,并给出了基于耦合模理论的辐射器不规则扰动段的设计方法。开发了基于耦合模理论、矢量衍射积分和物理光学法的仿真程序GQOMC-D,并将该程序的计算结果与文献报道结果进行了对比验证。利用该程序设计了一种110 GHz TE22,6模回旋振荡管准光模式变换器,仿真结果显示在输出窗上得到了场型较好的高斯波束,其模式纯度为98.4%,模式变换器的能量转换效率为94.7%。     

Design of a Quasi-Optical Mode Converter for a Frequency Step-Tunable Gyrotron

The quasi-optical mode converter for a frequency step-tunable gyrotron which consists of a dimpled-wall antenna (Denisov-type launcher) and a beam-forming mirror system has been optimized for 9 modes from TE_17,6 at 105 GHz to TE_23,8 at 143 GHz. The first mirror is a large quasi-elliptical focusing one; the second and third are phase-correcting mirrors with a non-quadratic shape of the surface. The results of calculations show that for these modes the Denisov-type launcher has a well-focused beam with low diffraction losses, and the radiation pattern presents an almost identical field shape for all modes considered. A multi-mode optimization of the phase-correcting mirrors with two different methods has been tested. The simulations show that the phase-correcting mirrors can be used for broadband operation in the frequency range from 105 GHz up to 143 GHz in the various design modes. This quasi-optical mode converter can achieve efficiencies of 94%-98% for converting the rotating high-order cylindrical cavity modes into the usable fundamental Gaussian mode.     

94 GHz回旋管准光模式变换器设计

基于几何光学理论和矢量绕射理论,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光高斯波束的模式变换器,采用伏拉索夫(Vlasov)辐射器和三级准光反射面实现了准高斯模TEM₀₀的横向输出.研究了Vlasov辐射器的工作机理,运用矢量绕射理论计算出波导辐射场,口面电流分布的方法计算反射面辐射场.通过编写程序设计了将94 GHz,模式为TE₆₂的毫米波转化为准光高斯波束的内置式准光模式变换器.关键词：94 GHz回旋管内置式准光模式变换器Vlasov辐射器矢量绕射理论     

Denisov-type quasi-optical mode converter forhigher-order asymmetric volume mode gyrotron北大核心CSCD

The principle and design method of Denisov-type quasi-optical mode converter is investigated indetail. The operation process of the Denisov-type launcher is analyzed by applying the geometrical optics, andthe Gaussian-like field distribution achieved on the waveguide wall is also derived. The method for designing arippled-wall launcher is proposed on the basis of coupled mode theory. A simulation code for Denisov-type qua-si-optical mode converter GQOMC-D is developed based on coupled mode theory, vector diffraction integrationand physical optics, which is compared to the design parameters and experimental results reported in literaturefor its validity. According to this code, a Denisov-type quasi-optical mode converter used in 110 GHz TE22.6mode gyrotron oscillators is designed. Simulation results indicate that a Gaussian-like beam is obtained at theoutput window with a scalar content of 98.4 % and a conversion efficiency of 94.7 %.     

110 GHz回旋管Denisov型准光模式变换器的研究与设计

对一种由Densiov型辐射器和四面反射镜面系统组成的准光模式变换器开展了详细的研究和设计。采用几何光学理论,分析了Denisov型辐射器的工作原理,推导了模式叠加形成高斯分布的过程。基于耦合模理论,提出了辐射器波纹波导的设计方法。针对110 GHz,TE22,6模回旋管的具体参数设计和优化了辐射器和镜面系统,编写仿真程序,对波导切口处辐射场和镜面散射场进行数值模拟。计算结果表明,输出窗口处得到较好的高斯波束,高斯效率达到95.8%,功率转换效率为94.7%。     

电磁发射器的原理与应用

传统的化学推进技术已不能满足人类的进一步要求，从原理和能源上变革发射技术势在必行，因此电磁发射技术便应运而生。因其在国防、航天等领域应用前景广阔，目前国内外电磁发射技术发展迅速。文章论述了电磁发射技术的发展历史、现状和电磁发射器的基本原理和广阔的应用前景。     

Millimeter-wave quasi-optical power combining techniques

6mm efficient power-combining has been achieved by introducing Gunn diodes directly into quasi-optical resonant cavity. The structure, the principle and the experiments are reported.     

Measurement of complex permittivity and permeability of materials by quasi-optical method

A quasi-optical method for measuring the complex permittivity and permeability of materials at millimeter and submillimeter wavelengths is proposed. In principle, this method is applicable not only to solid samples but also to liquid and composite samples. The theory and experiment are described in this paper.     

Design of a Quasi-Optical System Converting the TE06 Output Mode of a Gyrotron into a Gaussian-Like Beam

Gaussian optics can be used to design a quasi-optical system converting the TE₀₆ mode output (f=388 GHz) of a submillimeter wave gyrotron into a well-collimated, linearly-polarized free-space beam with a circular cross-section. A quasi-optical antenna produces a main beam with an elliptical cross-section, which is then converted by two mirrors into a well-collimated beam with a circular cross-section.     

Feasibility study of the eu home team on a 170GHz 1MW CW gyrotron for ECH on ITER

The gyrotron system forECH and burn control onITER requires at least50MW ofRF power at frequencies near170GHz operating inCW. To meet these requirements, high efficiency gyrotron tubes with 1MW power output capability are necessary, as well as simple coupling to either a quasi-optical or waveguide transmission line. The paper reports the feasibility study on the design of anITER-relevant gyrotron oscillator at170GHz,1MW CW employing a diode electron gun, an advanced internal quasi-optical converter, a cryogenically cooled single disk sapphire window, and a depressed potential collector. The operating mode selection and the cavity design is a compromise between many design constraints.     

Design of a Quasi-Optical System to Convert TE0n Mode Outputs of a Gyrotron into Gaussian Beams

In this paper we present a novel design of a quasi-optical system for conversion of gyrotron outputs into gaussian beams. It consists of a quasi-optical antenna, four focusing mirrors (parabolic cylinders) and a filter which removes the side lobes of the beam. The system is capable to convert three TE_0n mode outputs into gaussian beams with waist size of 16.7 mm as well as four TE_1n mode outputs into bi-gaussian beams with waist size of 10.9 mm in width and 16.5 mm in length.     

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.     

Conversion of Gyrotron Output into a Gaussian Beam Using the Far-Field

A compact system to convert gyrotron output into an intense gaussian beam has been designed by introducing an intermediate focusing element into the quasi-optical system. The design is significantly simplified by applying gaussian optics and confirmed by application of the Huygens equation. The beam quality is improved by truncating the sidelobes of the far-field. In spite of the beam truncation, only a small fraction (11 %) of the beam power is sacrificed.     

W波段边廊模回旋管准光模式变换器的研究与设计

详细研究并设计了一个由Vlasov螺旋开口辐射器和两级曲面反射器组成的边廊模回旋管准光模式变换器.首先采用几何光学理论研究了设计的Vlasov型准光模式变换器的工作机理,在此基础上,再利用矢量绕射理论中的口径场积分法和表面电流积分法编写了模拟仿真程序,最后结合W波段边廊模回旋管的具体设计参数,应用所编写程序详细分析了工作模式在此变换器中的模式变换过程.模拟结果表明,W波段回旋管中的TE_12,2边廊模在输出窗处被转换为能量集中的准Gauss波束.关键词：回旋管边廊模准光模式变换器W波段     

W波段边廊模回旋管准光模式变换器的研究与设计

详细研究并设计了一个由Vlasov螺旋开口辐射器和两级曲面反射器组成的边廊模回旋管准光模式变换器.首先采用几何光学理论研究了设计的Vlasov型准光模式变换器的工作机理,在此基础上,再利用矢量绕射理论中的口径场积分法和表面电流积分法编写了模拟仿真程序,最后结合W波段边廊模回旋管的具体设计参数,应用所编写程序详细分析了工作模式在此变换器中的模式变换过程.模拟结果表明,W波段回旋管中的TE_12,2边廊模在输出窗处被转换为能量集中的准Gauss波束.