Study on Ka-Band Sheet Beam Traveling Wave Tube Focused by Closed PCM

This paper reports a Ka-band sheet beam traveling wave tube (TWT) focused by a 0.2 T closed periodic cusped magnet (PCM) system. The TWT with one section of staggered double-vane slow-wave structure (SWS) is driven by a 0.8-A sheet beam with rectangular cross-sectional area of 3.2 mm?×?0.6 mm. This sheet beam TWT can produce 100 W output power, and the 3 dB band is 33–38.5 GHz. In order to improve the output power, an optimized sheet beam TWT with two sections of SWSs focused by a novel closed PCM system is proposed. The new closed PCM system is with annular magnetic blocks and can be fabricated and adjusted easily. The simulation shows that the optimized sheet beam TWT can produce 2000 W output power and the 3 dB band ranging from 33 to 40 GHz.     

多注太赫兹折叠波导行波管的设计与模拟

为解决太赫兹(THz)行波管工作电流过小、输出功率低等问题,提出了基模多注工作模式的折叠波导行波管(TWT)。首先,获得了基模多注折叠波导色散特性;然后,对基模多注折叠波导的传输特性进行了模拟计算;最后,完成了0.14 THz基模多注折叠波导行波管的注波互作用特性分析。电子注参数为12 m A,15.75 k V时,获得的3 d B带宽为25 GHz(128 GHz~153 GHz),最大增益为33.61 d B,最大峰值功率为23 W;电子注参数为30 m A,15.75 k V时,在0.14 THz处获得了38 d B增益,最大脉冲输出功率为63.1 W。该方法能够有效增大THz行波管的工作电流,提高互作用增益及效率、3 d B带宽、输出功率;在增益相同时,基模多注行波管可以做得更短、更紧凑。     

通信行波管转移特性测试方法

行波管一般作为微波放大器的末级,其性能好坏直接影响到通信整机系统的性能。在测试过程中,由于受到矢量网络分析仪的信号源输出功率和行波管增益限制,多采用固态放大器作为前级放大器推动行波管达到所需功率要求,因此不能直接精确得到行波管自身的特性。采用本测试方法可以去除固态放大器的影响,提高测试行波管的转移特性曲线的准确度。     

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.     

W波段宽带螺旋线行波管设计

提出了W波段螺旋线宽带行波管(TWT)设计方案,论述了高频系统、电子光学系统以及输能系统的计算与模拟。结果表明在80 GHz~100 GHz的范围内,能够得到大于15 W的输出功率,为开展W波段低电压螺旋线行波管的研制工作提供了依据。     

A high-power wideband traveling-wave tube with stepwise changes in the diameter of the drift channel

Results of the design of a high-power wideband (in the band 8–18 GHz) traveling-wave tube (TWT) with stepwise changes in the diameter of the drift channel are presented. The TWT is stable against self-excitation by a backward wave at high values of the accelerating voltage. It is shown that the output section of the device can be increased by a factor of 1.5 and the operating current can be raised by a factor of 1.3. These increases are attained owing to the 1.27-GHz diversity of the π-type frequencies of sections with different values of the channel diameter and owing to growth of the starting current corresponding to self-excitation by the backward wave. Application of the TWT with the interaction space that has steps of the channel diameter improved the electron efficiency by a factor of 1.2 and increased the output power by a factor of 1.6.     

X波段脉冲空间行波管输出结构可靠性研究

X波段脉冲空间行波管主要用于轻型SAR等雷达系统,要求行波管具有高功率、高效率、高可靠的性能。输出结构是行波管的重要部件,其可靠性不仅影响行波管的输出功率等性能,还影响行波管的稳定性与可靠性。该文针对X脉冲空间行波管输出结构进行可靠性研究,通过电、磁、热多物理场耦合的方式对它进行热、力结构可靠性分析,按分析结果对输出结构薄弱环节进行改进,耐冲击能力增强,并经过1000 h以上的整管老练及空间环境试验验证,输出结构具有较高的可靠性,满足空间环境试验及使用要求。     

Simulation of cold-test parameters and RF output power for acoupled-cavity traveling-wave tube

Procedures have been developed which enable the accurate computation of the cold-test (absence of an electron beam) parameters and RF output power for the slow-wave circuits of coupled-cavity traveling-wave tubes (TWT's). The cold-test parameters, which consist of RF phase shift per cavity, impedance, and attenuation, are computed with the three-dimensional electromagnetic simulation code MAFIA and compared to experimental data for an existing V-band (59-64 GHz) coupled-cavity TWT. When simulated in cylindrical coordinates, the absolute average differences from experiment are only 0.3% for phase shift and 2.4% for impedance. Using the cold-test parameters calculated with MAFIA as input, the NASA Coupled-Cavity TWT Code is used to simulate the saturated RF output power of the TWT across the V-band frequency range. Taking into account the output window and coupler loss, the agreement with experiment is very good from 60-64 GHz, with the average absolute percentage difference between simulated and measured power only 3.8%. This demonstrates that the saturated RF output power of a coupled cavity TWT can be accurately simulated using cold-test parameters determined with a three dimensional electromagnetic simulation code     

Ku波段高效率脉冲行波管的研制

简要介绍了Ku波段高效率脉冲行波管的设计、CAD计算和测试结果。通过对电子枪、聚焦系统、慢波电路、电子注和慢波线高频场大信号互作用的计算、收集极的设计,获得了符合新雷达系统技术指标要求的整管。实测结果为:在Ku波段2 GHz频带范围内,等激励、脉冲输出功率大于2.2 kW、效率大于30%。     

Improvement of the output power in TWTs by harmonic injection

The possibility of improving the fundamental output power of a traveling wave tube (TWT) using second harmonic injection is presented in this paper with theoretical, numerical, and experimental approaches. A calculus of the energy extracted from an electron beam subjected to a bi-harmonic field is presented in the low-gain regime, and it shows how the shape of the field can increase the fundamental extracted power. The phase difference between the fundamental and harmonic waves appears to be a key parameter for harmonic injection. The large signal code TUBH from Thales Electron Devices is used to simulate a TWT where both the fundamental and harmonic waves travel with the same velocity and the same growth rate. Harmonic injection simulations show that the fundamental output power is optimized when the total energy extracted from the beam is maximized, and the fundamental wave is favored to the detriment of the harmonic wave. A three-dimensional version of the code, called MVTRAD, is used to simulate an industrial TWT manufactured at Thales. Experimental measurements on this TWT completed this paper, showing a significant increase of fundamental output power with harmonic injection with up to 86% of additional power at 5 GHz.     

矩形耦合腔行波管的研究

为了得到高功率、高频率、大带宽的微波源,运用微波仿真软件CST对矩形耦合腔行波管这一新型的大功率器件进行了粒子模拟,得到了23．7kw的峰值输出功率,并且分析了行波管的工作电压与慢波系统的腔体数量对行波管工作特性的影响。结果表明,矩形耦合腔行波管具有较高的功率承载能力。     

钮销支撑螺旋线慢波结构色散特性及二次谐波抑制研究

寻求频带更宽、输出功率更大、体积更小的螺旋线行波管一直是研制工作的目标,二次谐波是影响宽带行波管工作的重要因素,本文对不同形式介质加载的螺旋线慢波结构进行了模拟,并对其中色散曲线最为平坦的钮销慢波结构进行了一维大信号模拟,证明改变螺距或夹持介质形状可有效展宽带宽、降低二次谐波功率。     

曲折双脊槽波导高功率宽频带太赫兹行波管

提出一种改进的曲折槽波导—曲折双脊槽波导提高太赫兹行波管的功率和带宽.针对这种新型慢波结构设计了一种新的传输波导作为输入输出能量耦合器.从高频特性仿真结果可以发现曲折双脊槽波导可以提高耦合阻抗并扩展带宽.此外, 粒子仿真结果表明当电子注加载27.4kV电压和0.25A电流时, 新型曲折双脊槽波导行波管在中心频率340GHz处输出功率能达到65.8W同时对应增益27.21dB.因此, 曲折双脊槽波导行波管可以用作宽带和高功率太赫兹辐射源.     

C波段80 W空间行波管的研制

针对C波段80 W空间行波管进行了优化设计。利用微波管模拟器套装(MTSS)模拟高频慢波结构、注波互作用,运用CST软件模拟了磁系统和输能耦合系统,在输能结构的设计中考虑了微放电效应,设计窗的功率阈值远远大于欧空局8 dB设计要求,降低了管子工作时因微放电而造成损坏的风险。通过MTSS着重优化了高频方案,最终制管完成测试,获得了输出功率大于80 W,效率大于65%,相移小于45°,AM/PM转换系数小于3.5°/dB。     

Power Flexible Ka-band Traveling Wave Tube Amplifiers of Up to 250-W RF for Space Communications

The latest model Ka-band helix traveling wave tube (TWT) amplifier designed and manufactured for onboard space satellite-communications systems at L-3 Communications Electron Technologies, Inc. is significantly improved over previous generations. This present-generation (model 999HA) TWT has demonstrated over 250-W RF output power over the 31.8- to 32.3-GHz deep-space frequency band with an overall efficiency exceeding 61% Robbins (Proc. IEEE Int. Vacuum Electron, 2006). In addition, the 999HA has low distortion and has demonstrated over 100-W RF output with 9-GHz instantaneous bandwidth. This TWT is expected to have application as a single unit or in power-combined systems so that deep-space missions can achieve a total RF output power of as much as 1 kW Wintucky (Proc. IEEE Int. Vacuum Electron, 2006). The 999HA can be mated to either 7-kV electronic power conditioners (EPCs) for low-power applications or to a recently developed 14-kV EPC (model 1693HC) to support higher power applications     

螺旋线行波管中功率洞问题的研究

宽带螺旋线行波管在一较窄的频带内出现饱和输出功率凹陷的现象被称为功率洞。功率洞对于放大器所应用的系统,特别是通信系统的整体性能会产生严重影响。本论文分析了宽带螺旋线行波管中功率洞产生的原因,介绍了一种解决功率凹陷的办法—渐变磁场法,并应用二维大信号注波互作用程序进行仿真,研究结果表明：采用渐变磁场法可以在一定程度上有效地抑制功率凹陷,使宽带螺旋线行波管在工作频带内的饱和输出功率随频率变化的曲线较为平坦。     

E波段折叠波导行波管集成极靴结构设计及仿真

为进一步提升毫米波折叠波导行波管的输出功率,通过整体加工的工艺方法,将折叠波导慢波结构和周期永磁聚焦系统在母材上同时加工,形成一种集成极靴结构。基于圆形注电子光学系统,设计了E波段折叠波导行波管的集成极靴结构。利用三维电磁场模拟软件(CST)的微波工作室,设计并模拟了慢波结构的冷特性参数,并根据慢波结构尺寸设计周期永磁聚焦系统。通过电磁工作环境仿真软件(OPERA)对磁场进行仿真验证,最终整管粒子数值模拟(PIC)计算结果表明,在61~71 GHz频带内可获得大于1 kW的饱和输出功率。该集成极靴结构在提供强轴向磁场的同时,具有结构紧凑、散热性好等优点。     

An Automatically Controlled Predistorter for Multilevel Quadrature Amplitude Modulation

In digital microwave transmission, the nonlinear characteristics in a high power amplifier, such as a TWT (traveling-wave tube) inhibit efficient output use. This note introduces a new predistorter control technique, and assesses the nonlinear compensation capability of a third-order predistorter incorporating this technique. Concerning 16-QAM (quadrature amplitude modulation) a 10 dB reduction in out-of-band emission and larger than 8 dBC/Nimprovement with respect to symbol error rate can be achieved at 3 dB TWT average output power backoff.     

一种高效率多注毫米波行波管的设计模拟

对某Ka波段7注耦合腔行波管慢波系统进行了模拟,分析了多注耦合腔行波管的单腔冷测特性、周期永磁聚焦（PPM）系统以及PPM聚焦系统下的注-波互作用,模拟结果表明：在中心频率34.5GHz处,其饱和输出功率达到829W,增益43.16dB,带宽约1.4GHz,电子效率高达30.37%。     

Space qualified low-/high-power radar TWTs

This paper is a report about recent development activities in the area of space-qualified pulsed traveling wave tubes (TWTs). For an economical development in such a low-volume market, the application of a modular design concept is necessary. As an example for such a concept, two projects will be described, a high-power X-band TWT with 6-kW peak output power and a low-power Ku-band TWT with 135-W peak output power.