回旋速调管放大器及其发展评述

回旋速调管放大器是一种具有重要发展前景的高功率相干毫米波源。该文简要介绍了回旋速调管的结构和工作机理,详细评述了国际上回旋速调管的发展状况及趋势,指出了发展中存在的一些关键问题,并提出了自己的建议。     

220 GHz回旋速调管放大器互作用理论的研究

应用注波互作用非自洽非线性模拟程序,对220GHz回旋速调管放大器的注波互作用进行了研究;分析了工作电流、工作电压、直流磁场对电子注效率影响。模拟结果表明,设计出的双腔回旋速调管放大器的电子效率为48%,相应的输出功率为20 kW。     

新型宽带大功率毫米波回旋行波管发射机

介绍了大功率毫米波雷达和应用于毫米波段微波管的特点.阐述了回旋管的分类和宽带大功率毫米波回旋行波管的工作原理、超导磁场的实现方法和Marx调制器等毫米波雷达发射机中的关键技术.根据回旋行波管放大器的工作特点,给出宽带大功率毫米波发射机系统方案及关键技术的解决方法.     

高功率毫米波回旋器件的需求及发展

本文概述了高功率毫米波回旋器件的主要应用领域和需求,简要介绍了在需求推动下的国际、国内高功率毫米波源——回旋器件研究的现状和发展,对未来高功率毫米波源的发展进行了展望。     

8mm二次谐波回旋速调放大器的研究

对8mm高功率二次谐波回旋速调放大器进行了理论研究和优化设计,已研制出回旋速调放大器实验样管,并进行了热测实验,得到了如下结果:在中心频率为35GHz的情况下,得到的最大脉冲输出功率为180kW,效率为13%,增益为21dB;在电子束电压为58kV,电子束电流为25A的情况下,得到了150kW的输出功率,3dB带宽110MHz(0.3%).     

新型回旋速调管放大器链式群聚腔的模拟与设计

对新型回旋速调管放大器的链式群聚腔—TE模簇腔进行研究，通过三维电磁模拟对其进行分析和计算，讨论了损耗介质对群聚腔Q值的影响，以及内外腔耦合孔数量对谐振特性的影响．模拟计算结果和冷测实验吻合得很好．最后，为正在研制中的Ka波段三次谐波倍增回旋速调管放大器设计了一种链式群聚腔。     

TriQuint新型宽带毫米波放大器

TriQuint Semiconductor公司推出四款新型高性能产品，这些产品是专门为点到点无线电、点到多点通信及商业或军用通信应用需求而设计的。这些新产品具有优异的电性能，在毫米波频率上将高输出功率和极宽带宽特性结合在一起。所有四款新推出的器件均符合无铅和RoHS规范。TGA4521是一款宽带毫米波驱动器放大器，     

140 GHz螺旋波纹波导小回旋行波放大器的研究

针对140 GHz回旋行波管,采用三折螺旋波纹波导作为慢波结构,通过色散特性分析优化螺旋波纹波导结构参数,达成了抑制模式竞争和扩展带宽的目的;依据布拉格衍射机理设计了输入耦合器,能够确保电子束有效流通以及信号稳定输入,且在136.5~144 GHz范围内,S_(21)>-0.5 dB。以小回旋电子注为激励源对该螺旋波纹波导回旋行波放大器进行了PIC仿真,当输入信号的频率为140 GHz、功率为50 W时,输出信号功率为223 kW,增益为36.49 dB;在134~142 GHz的频率范围时,输出功率在113~223 kW之间,3 dB带宽大于8 GHz。本文将螺旋波纹波导结构应用于140 GHz并取得了高增益和大带宽,对后续在更高频率的研究和工程应用具有较高的参考价值。     

大功率毫米波回旋管发射机的设计

阐述了利用新型大功率毫米波器件回旋管研制大功率毫米波雷达发射机的系统方案及设计难点。根据回旋管放大器的组成和特点，讨论了发射机中应用的全固态调制器等关键技术及其设计方法。指出了目前回旋管发射机存在的问题。     

具有高稳定性的超高增益回旋行波管放大器

该文结合线性理论和自洽非线性理论对Ka波段TE11模超高增益回旋行波管放大器的稳定性进行了研究。 研究揭示了回旋行波管中前向波绝对不稳定性和返向波振荡之间的区别,以及分布损耗技术对这两种自激振荡的抑制作用,并首次提出通过渐变磁场技术来提高系统的稳定性。基于该分析方法设计的Ka波段超高增益回旋行波管,采用电压100 kV,电流7 A,速度零散5％的电子注,获得了-1 dB的饱和功率带宽约5 GHz,最高增益约80 dB。     

Preliminary Design of a Harmonic-doubling Gyrotron Traveling Wave Amplifier

This study proposes a Ka-band harmonic-doubling gyrotron traveling-wave amplifier (gyro- TWT), using distributed wall losses in the input stage and mode-selective interaction circuit in the output stage, to improve the stability of the amplification. Based on a large signal simulation code, a saturated peak power of 163 kW with an efficiency of 15.5%, a gain of 31.1 dB, and a 3 dB bandwidth of 0.9 GHz is predicted for the gyro-TWT driven by 70 kV, 15 A electron beam with a velocity ratio of 1.2 and velocity spread 5% at 33.2 GHz.     

Beam-Wave Coupling Strength Analysis in a Gyrotron Traveling-Wave Amplifier

Mode competition is an important aspect of the stability analysis of a gyrotron traveling-wave amplifier (gyro-TWT). The concept of the coupling impedance is developed in this paper to investigate the beam-wave coupling strength in the electron cyclotron maser (ECM) interaction system. The coupling impedance brings a global consideration to study competition between the absolute instability and the convective instability in the circuit. The research reveals that the coupling impedance is proportional to the phase velocity of the mode, which means the coupling impedance of a mode in the lower k _z region is much stronger than the one in the higher k _z region. Interesting discussions are also carried out at the end of the paper. The coupling impedance provides an additional dimension of measurement to understand the ECM interaction.     

Slow Wave Gyrotron Amplifier with a Dielectric Center Rod

The broad-band capability of the gyrotron amplifier with a dielectric center rod is investigated. The dispersion relation for the TE mode perturbation is obtained, and the system parameters for the optimum bandwidth are obtained for a small axial velocity spread. It is found that the dielectric center rod extends the frequency range of the intermediate wavelength mode (IWM), and reduces the contribution of the troublesome short wavelength mode (SWM). The bandwidth and the gain due to the IWM for the center rod geometry are superior to those for the wall clad dielectric gyrotron.     

Study of a Ka-Band TE11 Mode Gyrotron Traveling-Wave Amplifier

A Ka-band gyrotron traveling wave (gyro-TWT) amplifier with high power and wide bandwidth operated in the fundamental TE11 circular mode is presented in detail. The stability of the gyro-TWT amplifier using linear and nonlinear theory is analyzed. The distributed loss technique is employed in the interaction circuit which guarantees the amplifier zero-drive stability. The effects of the parameters such as input power, driver frequency, magnetic field on the performance of the gyro-TWT is discussed. The simulation results show that the gain and the bandwidth of the designed Ka-band gyro-TWT are about 60.0 dB and 1.4 GHz at constant drive with an axial velocity spread Dv_z \mathord

Characteristics and Optimum Operating Parameters of a Gyrotron Traveling Wave Amplifier

Characteristics and optimum operating parameters are determined for a new type of high-power high-efficiency generator of millimeter waves known as a gyrotron traveling wave amplifier. In the example consided, wave amplification results from the interaction of a TE/sub 01/ waveguide mode with the fundamental cyclotron harmonic of an electron beam. The parameter optimization involves the determination of the point of maximum device efficiency as a function of beam density, beam energy, beam positioning, and external magnetic field for the output power required. An analytical linear theory and a numerical simulation code form the basis of theoretical calculations. As a result of the extensive survey in parameter space, the peak efficiency in the beam frame has been found to exceed 70 percent. This result has been applied to the specific design of a 35-GHz amplifier with output power ~340 kW, a power gain of 2 dB/cm, and a laboratory frame efficiency of 51 percent.     

Analysis of a Disc-Loaded Circular Waveguide for Interaction Impedance of a Gyrotron Amplifier

A rigorous electromagnetic analysis of a circular waveguide loaded with axially periodic annular discs was developed in the fast-wave regime, considering finite axial disc thickness and taking into account the effect of higher order space harmonics in the disc-free region and higher order modal harmonics in the disc-occupied region of the structure. The quality of the disc-loaded circular waveguide was evaluated with respect to its azimuthal interaction impedance that has relevance to the gain of a gyrotron millimeter-wave amplifier (gyro-traveling-wave tube) in which such a loaded waveguide finds application as a wideband interaction structure. The results of electromagnetic analysis of the structure with respect to both the dispersion and azimuthal interaction impedance characteristics were validated against the commercially available code: high frequency structure simulator (HFSS). The analysis predicts that the value of the interaction impedance at a given frequency decreases with the increase of the disc hole radius and disc periodicity. The change of the axial disc thickness does not significantly change the value of the interaction impedance though it shifts the frequency range over which appreciable interaction impedance is obtained. Out of the three disc parameters, namely the disc hole radius, thickness and periodicity, the lattermost is most effective in controlling the value of the azimuthal interaction impedance. However, the passband of frequencies and the center frequency of the passband both decrease with the increase of the disc periodicity. Moreover, the disc periodicity that provides large azimuthal interaction impedance would in general be different from that giving the desired dispersion shape for wideband interaction in a gyro-TWT, suggesting a trade-off in the value of the disc periodicity to be chosen.     

Ka波段二次谐波回旋行波管放大器的研究

二次谐波回旋行波管放大器的互作用磁场比基波回旋行波管放大器的磁场降低了一半,从而降低了设计难度,具有广阔的应用前景。通过对周期介质加载结构的Ka波段二次谐波回旋行波管电子枪、高频结构、模式竞争以及注波互作用研究,确定了Ka波段TE02模二次谐波回旋行波放大器的基本工作参数,通过PIC模拟计算,在电子注电压为90 kV,注电流为25 A时,获得了大于200 kW的输出功率,超过40 dB的增益。     

Analysis of the Stability in a Gyrotron Traveling Wave Amplifier with the Reflection at Output Port

Based on the linear theory of gyrotron traveling wave amplifier (gyro-TWA) and the boundary condition, the model of the gyro-TWA with the reflections at the output port is established. The influence of the reflections on the wave gain rate, the back wave starting length and the back wave starting current for a Ka band TE₀₁ gyro-TWA at fundament is analyzed. The simulating results show that the increased reflection may lower its stability to some extent.     

Theory and Simulation of the Gyrotron Traveling Wave Amplifier Operating at Cyclotron Harmonics

An analytical expresion for the efficiency of the gyrotron traveling wave amplifier is derived for the case of nonfundamental cyclotron harmonic interaction. It scales the efficiency with respect to the modes and parameters of operation. This relation, together with a general linear dispersion relation, also derived in the present paper, gives the characteristics and optimum operation conditions of the gyrotron traveling wave amplifier.