螺旋线行波管大信号相互作用模型的改进

由于Rowe模型的能量不守恒性,使它用于实际的行波管设计时,特别是相速跃变的螺旋线行波管的设计时会产生较大的误差。本文提出的改进模型以能量守恒作为电子注和波之间的相互作用规范,所以在不计空间电荷力时,高频场的功率和电子注消耗的功率精确相等。用新模型的计算结果比用Rowe模型的更接近实际情况,特别是在变相速的设计中。     

Improvement on the large signal interaction model for helix TWT

Because of the nonconservation of energy in the Rowe's model for the large signal interaction in TWTs. The Rowe's model produces considerable error in the TWT design, especially, in the design of helix TWT with velocity jump. A modified model which is based on conservation of energy is suggested to improve the accuracy of the design of TWT. By the new model, when the loss and the space-charge are neglected, the energy got by the circuit is accurately equal to that given by the electron beam. And all results obtained by the new model are more in agreement with the actual cases than those by Rowe's model.     

行波管关断方式对应用系统可靠性的影响

行波管在工作一段时间以后其电子枪各极间绝缘电阻可能发生变化,因此针对行波管的特点,设计出可靠的工作电源及行波管关断电路是保证武器装备可靠性的重要因素之一。在行波管电子枪极间绝缘电阻变小时,某应用系统行波管关断电路因不能使行波管完全关断,造成管体温度上升,保护电路动作,从而导致出现了雷达发射机无法及时开启的故障。文中通过对2种行波管关断方式等效电路的讨论,提出了避免应用系统故障的有效关断电路模式。     

Effects of the attenuator on the nonlinear phase distortion of a traveling-wave tube

An experimental and theoretical examination indicates how the non-linear phase distortion of a traveling-wave tube is affected by relevant factors, especially the circuit loss. The effect of the loss is found to be about ten times as large as theoretically predicted, An approximate formula is derived for the phase distortion of a TWT with an attenuating central section, and comparison is made with experimental values.     

Large Signal Analysis and Computation for Millimeter Wave TWTs

The large signal operating equations are described by charge plate model in traveling wave tube (TWT). The large signal nonlinear equations have been solved by calculating inductive current of electron beam, circuit voltage exited by electron beam, beam velocity and phase affected by circuit field. The calculating results are given for Ka-band TWT in the paper.     

微带型行波管外平衡器的计算机辅助设计和实验研究

利用微带电路作成的行波管外平衡器的理论研究和实验工作已经完成。为了进一步改进行波管的性能,本文对平衡器的设计计算方法进行了讨论,改进设计了一个单级平衡器,使在2.87.0GHz的频带内增益起落从11.6dB降为2.74dB。同时提出不对称增益特性的双级复式补偿平衡器的概念和方法,设计和研制了一个双级平衡器。利用计算机对微波电路参量进行了优选调整后,在2.57.5GHz的频带内,增益起落从13.6dB降为2.73dB。实验结果的变动量为5dB。     

Optimum Design of a Potentially Dispersion-Free Helical Slow-Wave Circuit of a Broad-Band TWT (Short Paper)

The results of an equivalent circuit analysis are studied for a potentially dispersion-free slow-wave circuit of a TWT which consists of a dielectric-supported helix in a metal shell provided with vanes. The optimum vane dimensions are predicted, which should be helpful in broadbanding the performance of a TWT.     

Performance and Application of Slow Wave Circuits for Power TWT in Millimeter Wave

In millimeter wave range, high-power traveling wave tube (TWT) is a key device with broadband and high-power amplification. Basis of comparing traditional and new type slow wave circuits for high-power TWT in MMW, analysis and computation of propagating and RF performance for folded wave circuit are carried out. Theoretic calculation and experimental test show that folded wave circuit is an ideal slow wave structure for broadband and high-power TWT in MMW. There is extreme wide application for the circuit in high-power TWT. This development possesses important consult value to designer for MMW power amplifiers.     

Design of Overmoded Interaction Circuit for 1-kW 95-GHz TWT

Advanced simulation tools were used to design major components for a 95-GHz traveling-wave tube (TWT) providing approximately 1-kW of average power. This output power would be challenging, if not impossible, using a fundamental mode circuit TWT design, because of beam-current density and thermal-mechanical-stability issues. We addressed these limitations using an overmoded interaction circuit. The program investigated the circuits' thermal and electrical performance, including the effect of multiple-propagating modes and spurious oscillations. We also completed the designs for the electron gun and periodic permanent magnet. The design results for the 1-kW 95-GHz TWT are promising.     

Diamond-studded helical traveling wave tube

A novel method of millimeter-wave traveling wave tube (TWT) slow-wave circuit fabrication, employing laser micromachining and the in situ growth of diamond studs as an insulating dielectric, has been developed, which would enable a new class of very wideband, low distortion, high-efficiency amplifiers. Because the slow-wave circuit is supported by an array of diamond studs, rather than the conventional dielectric rods, we have named this novel device the diamond-studded TWT. Diamond strips have been successfully grown on a molybdenum tube and a diamond-studded helix has been produced using laser micromachining. Computer analysis of the slow-wave structure indicate that this fabrication technique leads naturally to a circuit with nearly flat dispersion over a frequency range, in some configurations, of more than four octaves. Typically, wide bandwidth can only be achieved by reducing efficiency; however, this fabrication technique increases the interaction impedance of the circuit, enabling high efficiency operation without sacrificing bandwidth. The very low dispersion also results in a coupling impedance that is relatively insensitive to frequency that may enable low reflection coupling over a wide frequency band. The resulting slow-wave circuit is essentially a brazed structure and, therefore, inherently robust thermally and mechanically. The manufacturing technology being pursued is applicable to any millimeter-wave helical or helix-derived TWT.     

Design and fabrication of a sub-millimeter multi-beam folded waveguide structure

A novel multi-beam folded waveguide (MBFW) circuit, which can enhance the output power and interaction efficiency of sub-terahertz (THz) traveling wave tube (TWT), is presented in the paper. Operating with fundamental mode and multiple electron beams means that a larger beam current can be used for a higher output power. The characteristics of the MBFW structure are analyzed and optimized. Compared with the single-beam folded waveguide (SBFW) TWT, the output power of the MBFW TWT increases from 3.64 W to 25.45 W at 140 GHz and its electronic efficiency increases from 1.06% to 7.4% under the conditions of an input peak power of 10 mW, a beam voltage of 9.55 kV and a current of 12 mA. The optimized MBFW structure can be successfully fabricated by micro milling, with dimension errors below expectation, and the measured transmission characteristics are in good agreement with the design.     

Novel high-gain, improved-bandwidth, finned-ladder V-bandtraveling-wave tube slow-wave circuit design

In this paper, the three-dimensional electrodynamic simulation code MAFIA (Solution of MAxwell's Equations by the Finite-Integration-Algorithm) is used to investigate methods of increasing the bandwidth and lowering the operating voltage of the ring-plane circuit. Calculations of frequency-phase dispersion, beam on-axis interaction impedance, attenuation, and small-signal gain per wavelength were performed for various geometric variations and loading distributions of the ring-plane TWT slow-wave circuit. Based on the results of the variations, a circuit termed the finned-ladder TWT slow-wave circuit was designed and is compared here to the scaled prototype ring-plane and a conventional ferruled coupled-cavity TWT circuit over the V-band frequency range. The simulation results indicate that this circuit has a much higher gain, significantly wider bandwidth, and a much lower voltage requirement than the scaled ring-plane prototype circuit, while retaining its excellent thermal dissipation properties. The finned-ladder circuit has a much larger small-signal gain per wavelength than the ferruled coupled-cavity circuit, but with a moderate sacrifice in bandwidth     

Experimental Investigation of a Novel Circuit for Millimeter-Wave TWTs

A novel folded waveguide circuit that features thick iron pole pieces with hollow centers was built as part of a periodic-permanent-magnet-focused W-band single-stage test-vehicle traveling-wave tube (TWT). These hollow centers, which comprise part of the slow wave circuit, increase the rms axial field and significantly reduce the unwanted transverse field imbalance. For this TWT, a tetrode gun that creates an ultralaminar 20-kV 0.25-A nominal electron beam was used. It was demonstrated that this gun and magnetic structure can provide greater than 97% beam transmission for peak beam power levels as high as 9.25 kW (25 kV, 0.37 A). The unplated circuit, operating around 91 GHz on the edge of a passband, exhibits between 10 dB and 12 dB gain that compares favorably with results of device modeling utilizing the 3D particle-in-cell code Magic3D. Using a feedback approach to characterize large-signal operation, the tube generated 40 W of regenerative oscillator power. Design-optimized versions of this circuit show promise of enabling W-band TWT amplifiers that provide up to 300 W of peak RF output power     

Design of high-efficiency wide-bandwidth coupled-cavitytraveling-wave tube phase velocity tapers with simulated annealingalgorithms

The output circuit section of a traveling-wave tube (TWT) routinely contains an RF phase velocity taper for the purpose of increasing RF output power and efficiency. By slowing the RF phase velocity in approximate synchronism with the decelerating electron beam bunches, the taper increases power transfer from the beam to the RF wave. Recently, the computational optimization technique of simulated annealing was shown to be very effective in the design of an RF phase velocity taper that significantly increased computed RF power and efficiency of a coupled-cavity TWT. In this paper, two new broadband simulated annealing algorithms are presented that optimize (1) minimum saturated efficiency over a frequency bandwidth and (2) simultaneous bandwidth and minimum efficiency over the frequency band with constant input power. The algorithms were incorporated into the NASA 2.5-dimensional (2.5-D) coupled-cavity TWT computer model and used to design optimal phase velocity tapers using a 59-64 GHz coupled-cavity TWT as a baseline model. Compared to the baseline taper design, the computational results of the first broadband algorithm showed an improvement of 73.9% in minimum saturated efficiency. The second broadband algorithm indicates an improvement of 272.7% in minimum RF efficiency with constant input power drive and an increase in simultaneous bandwidth of 0.5 GHz over that calculated for the baseline TWT     

宽频带高纯谱脉冲行波管发射机的设计

介绍一部脉冲行波管发射机的设计，重点叙述高压电源、控保电路以及栅极调制器电路的设计。最后给出发射机的频谱及RF包络的图形。     

新型大功率毫米波螺旋线行波管高频系统研究

该文探讨了CVD金刚石材料在宽带毫米波螺旋线行波管中的应用,研究了两类非杆状新型CVD金刚石夹持的螺旋线高频结构,利用MAFIA分析了它们的色散特性、耦合阻抗和衰减常数,与传统的矩形BeO夹持杆和矩形CVD夹持杆高频结构进行了对比,最后将这两类新型高频结构替代国内某毫米波行波管(26-40GHz)中的矩形BeO夹持杆螺旋线高频结构,利用宽带大功率行波管CAD集成环境中的注波互作用模块分析了其大信号工作特性。结果表明,分立CVD金刚石夹持高频系统兼顾了超宽带和大功率,同时由于金刚石直接和螺旋线及金属翼片大面积接触,该结构还具有极好的散热能力,是一种有重要应用前景的高频结构。     

Study of Propagating Characteristics for Folded Waveguide TWT in Millimeter Wave

Folded waveguide circuit (FWC) is an ideal slow wave structure for broadband power traveling wave tube (TWT) in millimeter wave. But owing to changes of propagating character by reflecting of waveguide bend and electron beam hole, stopband can be formed. On the basis of computation of the stopband, effects of the dimension of FWC on stopband width are analyzed. It is available for design in FWC TWT.     

毫米波折叠波导行波管的研究

采用等效电路方法和电磁场仿真软件Ansoft HFSS分析了折叠波导行波管的结构参数对其高频特性的影响,并在此基础上确定了Ka波段折叠波导行波管的尺寸.利用三维非线性粒子模拟软件MAGIC3D建立了两段式折叠波导行波管的模型,模拟研究了切断区长度和位置对折叠波导行波管的饱和输出功率及第2段电路单位长度增益的影响.最后设计了一个工作于33～36GHz的两段式折叠波导行波管,其输出功率的波动小于1dB,最大连续波输出功率达670W,对应电子效率高达7.55％.     

提高宽带毫米波行波管效率研究

针对影响宽带毫米波行波管效率的主要因素,对提高行波管效率的相关实用化技术进行了研究。通过螺旋线线路渐变技术、降低高频损耗、多级降压收集极三个方面的研究,使现有某一宽带毫米波行波管总效率由原来的10%提高到20%以上。     

W波段两种梯形线慢波电路过模工作研究

针对W波段过模行波管可能采用的两种梯形线慢波电路结构进行了模拟计算,分析了工作在过模情况的可能性。结果表明传统梯形线慢波电路并不适合工作于高次模式,而悬浮梯形线慢波电路在第三个模式则有着相对较高的互作用耦合阻抗,可以在W波段实现1000W的功率输出。