Modern multistage depressed collectors—A review

Well performing multistage depressed collectors (MDC's) have been developed for traveling-wave tubes (TWT) in an sizes fitting the requirements of wide-band countermeasures, radars, and ground and space communications. In the case of NASA-type symmetric collectors, rigorous analytical tools were developed that permit accurate a priori designs of MDC's for any given helix-type tube. Although only few verified cases of MDC's augmenting communications klystrons are known, the resulting performance and available theories indicate significant gains in reducing power consumption by TV and other klystron amplifiers without the deleterious effects of backstreaming.     

多级降压收集极行波管高压电源的设计

为了提高真空管雷达发射机的效率、缩小整机的体积和重量,常使用多级降压收集极行波管作为功率射频放大器.为了保证多级降压收集极行波管高增益、高效率和良好线性等性能发挥的更好,就要在行波管每个电极上加合适的电压,确保行波管内建立稳定的电场.因此,根据行波管各电极的特性合理地选择各收集极的电压以及合理的设计高压电源显得尤其重要.文中结合多级降压收集极行波管的工作特性介绍了4种高压电源的设计方法及其特点.     

Experimental verification of a computational procedure for the design of TWT-refocuser-MDC systems

A comparison of analytical and experimental results is presented for a high performance dual-mode helix TWT, equipped with multistage depressed collectors (MDC), and operated over conditions ranging from saturation to the linear regime. The computations are carried out with advanced multidimensional computer programs which model the electron beam as a series of disks or rings of charge and follow their trajectories from the RF input of the TWT, through the slow-wave structure, through the refocusing system, to their points of impact in the depressed collector. Twr performance, collector efficiency, and collector current distribution are computed and compared with measurements. Very good agreement is obtained between computed and measured TWT performance and collector efficiencies. The analytical techniques were subsequently applied to the design of a smaller MDC of nearly equal efficiency.     

D波段行波管三级降压收集极的设计

效率是行波管(TWT)的重要技术指标,为提高某一0.22 THz折叠波导行波管的效率,需设计多级降压收集极。对注波互作用后的电子注信息进行分析,估算收集极效率最高时的电压设置。利用电磁仿真软件对三级降压收集极电极结构和电压设置进行仿真优化,得到效率大于87.5%,回流电流小于0.328 9 mA的轴对称三级降压收集极;在第二电极入口采用斜口结构进行仿真优化,得到回流电流小于0.075 mA的非轴对称三级降压收集极。结果表明,采用斜口结构可以有效降低0.22 THz行波管多级降压收集极的回流电流。     

基于可回收能力的空间行波管高效率研究

效率是行波管设计的重要指标之一。对于空间行波管,效率的提高可以立即转化为经济效益。本文通过对注波互作用电路参数的优化设计,得到便于收集的“作用完了”的电子注。通常具有高电子效率的电子注,能量分散较大,不利于收集。通过设定电子效率大于25%这个限制条件,来保证了具有高可回收能力的电子注,同时具有较高的输出功率。在遗传算法中调用3 维MTSS,用来计算注波互作用后的输出能量和电子能谱图。并对一支Ku 波段的螺旋线行波管进行优化设计,从数值计算结果来看,可回收效率提高到了89%,且具有26.9%的电子效率。     

Small-size 81- to 83.5-percent efficient 2- and 4-stage depressed collectors for octave-bandwidth high-performance TWT's

In a joint USAF-NASA Program, Lewis Research Center is carrying out an efficiency improvement program on traveling wave tubes (TWT) for use in electronic counter measures (ECM) by applying multistage depressed collector (MDC) and spent beam refocusing techniques developed at Lewis. In the analytic part of the effort, three-dimensional electron trajectories are computed throughout the TWT. Trajectory computation continues through the spent beam refocuser and the depressed collector. Collector efficiency, collector losses, and overall efficiency are identified and computed. On the experimental side, tube performance is evaluated first without the MDC; then, the spent beam is analyzed for symmetry, circularity, and velocity spread. Finally, the MDC is attached and its performance optimized and evaluated. The three-dimensional theory, for ideal tubes, predicts a MDC-efficiency, at mid-band, of 81 percent for a 2-stage MDC with symmetric, circular, and optimally refocused beams and 85.5 percent for a 4-stage MDC. Experimental results to date have yielded MDC efficiencies of a minimum of 81 and 83 percent for a 2- and 4-stage MDC, respectively, across a one-octave bandwidth of a 4.8 to 9.6 GHz 330-to-550-W TWT.     

UC3901在行波管收集极电源中的应用

介绍了行波管的性能,阐述了收集极电源的特点,论述了UC3901在行波管收集极电源中的应用。     

Verification of an improved computational design procedure for TWT-Dynamic refocuser-MDC systems with secondary electron emission losses

A computational procedure for the design of TWT-refocuser-MDC systems was used to design a short "dynamic" refocusing system and highly efficient four-stage depressed collector for a 200-W 8-18-GHz TWT. The computations were carried out with advanced multidimensional computer programs which model the electron beam as a series of disks of charge and follow their trajectories from the RF input of the TWT, through the slow-wave structure and refocusing section, to their points of impact in the depressed collector. Secondary emission losses in the MDC were treated semiquantitatively by injecting a representative beam of secondary electrons into the MDC analysis at the point of impact of each primary beam. A comparison of computed and measured TWT and MDC performance showed very good agreement. The electrodes of the MDC were fabricated from a particular form of isotropic graphite that was selected for its low secondary electron yield, thermal expansion characteristics, ease of machinability, and vacuum properties. This MDC was tested at CW for more than 1000 h with negligible degradation in TWT and MDC performances.     

一种应用于合成孔径雷达的高效率脉冲行波管的研制

本文介绍了一种Ku波段脉冲行波管的研制结果,其总效率在使用一级降压收集极的情况下已经达到30%以上。     

Ka波段30W空间行波管

介绍了未来星际通讯用Ka波段30W空间行波管的最新研究进展。行波管电子枪采用传统的皮尔斯型电子枪,高频结构采用螺旋线慢波结构和品型夹持结构,为了保证较高的收集极效率,采用四级降压收集极。测试结果表明在工作频带内行波管输出功率超过34.6W,总效率超过47.5%。当行波管工作于低频状态时,行波管总效率超过了50%,已达到目前国外同等功率量级Ka波段空间行波管研究水平。     

The Key Technology of Efficiency Enhancement for Traveling Wave Tubes in Millimeter Wave

The efficiency enhancement methods for helix and coupled cavity traveling wave tube (TWT) in millimeter wave (MMW) are described. The interaction efficiency has been reached 14.56% by dynamic velocity taper in Ka-band TWT. Efficiency improvement has been carried out by used copper helix for broadband MMW TWT. Owing to a ferruleless coupled cavity TWT used phase-adjusted taper, the interaction efficiency has been increased from 9.6 to 22.6%. Finally, enhancing collector efficiency used multistage depressed collectors is discussed in the paper. These concept and technology of the approach are very useful for tube designer.     

高效率毫米波行波管

行波管可以应用于雷达和卫星系统中,具有高效率、高功率和高增益的特点。文章介绍了国际上高效率毫米波行波管研制现状,分析了提高行波管效率的几个主要方法,包括提高电子效率、收集极效率及高性能电子光学技术。     

耦合腔行波管电参量对降压收集极特性的影响

该文基于Orprogr软件,在X波段模拟设计出耦合腔行波管的期待电性能,并利用互作用后的电子注为入口条件,优化设计出收集效率大于71.5%、电子注着陆相对均匀的三级降压收集极。在上述条件下,讨论了电子进入收集极层流性(速度比)、电极形状、电极电压以及收集极内电场分布对电子运动的影响,从物理上给出了电子注在收集极表面着陆特点的详细分析。     

一种应用于Ku波段脉冲行波管的两级降压收集极的研究

本文介绍了一种应用于Ku波段脉冲行波管的两级降压收集极的研制结果,应用了该两级降压收集极的Ku波段脉冲行波管的总效率已经达到40%以上。     

The tilted electric field soft-landing collector and its application to a traveling-wave tube

If a collector in a beam-type tube captures all the electrons at almost zero velocity, the tube efficiency will approach unity. Such a collector might be called a soft-landing collector. This paper describes the principle, design theory, preliminary experimentation, and application of a new type collector in which an almost complete soft landing can be realized. The experimental TWT equipped with this collector achieved an efficiency improvement from 19 to 46 percent.     

Secondary electron emission properties of conducting surfaces for use in multistage depressed collectors

Secondary electron emission measurements were made in an Auger spectrometer, which allowed the surface chemical constituents to be determined also. Materials studied were beryllium, soot, pyrolytic graphite, copper, titanium carbide and, tantalum. Pyrolytic graphite roughened by sputter etching showed the most favorable results for depressed collector use.     

计算机设计的降压收集极的实验验证

本文提出了利用文献[1]的轴对称多级降压收集极计算模型和通用程序进行设计的方法,以及叙述了用该法设计的收集极在高效率C波段行波管中的使用情况。     

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%。     

Ka波段行波管提高效率研究

本文针对Ka波段高效率行波管的特点,采用专门的设计技术提高电子互作用效率、收集极效率、电子流通率和采用匹配良好的输能系统,实现了Ka波段30 W,55 W,80 W和100 W系列连续波行波管,效率达到45％～60％范围.     

The positively tapered traveling-wave tube

A new and unexpected concept of TWT circuit modification which results in high basic beam and depressed collector efficiencies is described. The test results which are presented disclose that 50 percent depressed collector efficiency has been achieved over a 10 per cent bandwidth, and that maxima of 42 and 52 percent, respectively, of beam and depressed collector efficiency have been measured at spot frequencies. The tube which produced these results contained a single continuous helix tapered at the output end so that the phase velocity of the fundamental circuit wave was increased.