Vacuum electronics at the dawn of the twenty-first century

In this introduction to the Special Issue on vacuum electronics, the history, operating principles, and recent technological trends of vacuum electronic devices are reviewed. The development of microwave power tubes is described and improvements in these devices over the past quarter of a century are highlighted. These improvements have been substantial and have been driven by modern high-power applications and by advances in materials and computational science. The second part of this paper describes the advent of a new class of vacuum electronics generator as involving relativistic electron beams and interaction with fast waves (e.g., gyrotrons, free-electron lasers). These new types of generators are opening the electromagnetic spectrum beyond the microwave region (i.e., millimeter-wave, infrared, ultraviolet, and even X-ray) for applications of high-power, coherent generators of electromagnetic radiation     

一种紧凑型大功率微波固态源

传统的微波源主要由行波管、磁控管、返波管等电真空器件实现,但因其工作电压高、功耗大、体积大,导致在使用安全性、利用效率和便携性等方面存在不足。而微波固态源由于具有效率高、谐波抑制性能好、稳定性高等优点,正逐步替代传统微波源,有着很好的发展空间。设计了一种紧凑型大功率微波固态源,采用锁相环作为信源,通过三级功放级联对微波信号进行逐级放大,最终输出频率为915 MHz、功率为300 W 的微波信号。测试结果表明该固态源的工作效率≥70%,二次谐波抑制≤-40 dBc,三次谐波抑制≤-50 dBc。该设计在微波加热和解冻等方面具有很好的应用前景。     

场发射锥尖的制备及特性研究

研究了倒金字塔填充型锥尖及正向刻蚀硅尖的制备工艺,采用了两种封装结构测试了场发射硅尖阵列的发射特性,并分析比较了这两种结构的特点及用于制备高频微波器件的可能性。     

Investigation of signal spectrum multiplexing in nonlinear structures by means of a quasi-stationary method

The transmission of a complex signal through nonlinear structures (semiconductor diodes, high-power transistor amplifiers, microwave vacuum amplifiers, etc.) is investigated by means of a quasi-stationary method, and functional models of devices are applied. The models use the quasi-stationary method of analysis of multifrequency signal transformation. Certain properties and peculiarities that are exhibited by nonlinear devices and that induce so-called spectrum multiplexing, i.e., formation of combination components, including those observed within the basic spectrum, are considered. The possibilities of spectrum multiplexing in nonlinear elements with a polynomial quadratic, cubic, or more complicated characteristic are discussed.     

Spin transport and microwave self-oscillations in magnetic heterostructures with giant magnetoresistance

The phenomena of spin transport and spin-transfer torque between layers of a magnetic hetero-structure with conducting and tunneling interlayers, which can lead to switching of micromagnetic states in the structure??s layers and microwave generation, are considered. The features of spin transport in the field-emission mode for magnetic tunnel structures and problems of the current generation of spin waves in the magnetic film during local spin pumping are discussed. The possibility of the phase locking of the system of nanogenerators on a common magnetic platform and prospects for using nanogenerators based on the effect of spin transport in microwave communication engineering are analyzed.     

真空电子器件输出窗次级电子倍增效应研究进展

真空电子器件在毫米波和太赫兹波频段具有大功率的天然优势,可用于构建高效率、大功率的毫米波和太赫兹辐射源,对高功率微波技术及太赫兹技术的发展具有十分重要的意义。输出窗是真空电子器件的关键部件,输出窗击穿是器件失效的主要原因之一,而次级电子倍增效应被认为是输出窗击穿的主要原因。本文梳理了目前分米波及厘米波波段真空电子器件输出窗的研究现状,在此基础上梳理了这一领域未来研究的主要发展方向,以期为未来真空电子器件向更高功率和更高频率等级发展提供参考。     

大功率速调管的技术现状和最新进展

大功率速调管是一种基于速度调制原理将电子注能量转换成微波能量的微波真空电子器件,它具有高功率、高效率、高增益和高稳定性等优点,是微波真空电子器件中脉冲功率和平均功率最高的器件。速调管自20世纪30年代发明以来,在粒子加速器、雷达和通信等微波电子系统,以及真空电子技术进步的推动下,已发展成功多种类型大功率速调管,其频率覆盖整个微波,并扩展到毫米波和太赫兹波段,最大脉冲功率达200MW,最大平均(连续波)功率达MW级。近年来,在高能粒子加速器、宽带雷达系统、毫米波和太赫兹波电子系统的推动下,大功率速调管取得了令人瞩目的进步,本文比较系统地介绍了大功率速调管的技术现状和在提高功率、提高效率、提高工作频率、展宽带宽等方面取得的最新进展。     

Basic and applied studies of field emission at microwave frequencies

Experimental field-emission microwave devices ("femitrons") are described which locate a cold field-emission cathode in the gap of a cavity resonator to achieve direct emission bunching of the electron beam. These devices exploit the high emission density and strong nonlinearity of field cathodes to produce beams with high current density, strong bunching and high harmonic content. An analysis of beam bunching and harmonic content is presented, based on certain assumptions and particularly on the validity of the field-emission law at microwave frequencies. Several independent experiments are discussed which verify these assumptions and confirm the predicted bunching and harmonic content, thus establishing the feasibility of developing femitrons into high-efficiency amplifiers or oscillators, or for the performance of nonlinear operations such as frequency mixing, harmonic generation or rectification of microwave power. Recent developments and current performance of compact multiple-needle field cathodes with relatively high peak current and perveance capability are presented. Based on these, and on preliminary tests at intermediate power levels of microwave devices using such cathodes, a brief evaluation is made of the probable performance and possible applications of femitron devices.     

美欧高功率微波技术研究现状及发展趋势

当前,随着无人机集群等新型作战武器的逐步实战化,作为其反制手段的高功率微波等定向能武器受到了高度关注。美欧各军事大国均大力推进高功率微波技术研究及武器装备研发,部分高功率微波武器装备已经完成了概念演示验证,正逐步形成实战化装备。从高功率微波武器关键技术研究和武器装备发展2个方面,对高功率微波领域研究现状进行了梳理,重点介绍了脉冲功率驱动源技术、高功率微波产生技术和高功率微波辐射技术方向的研究进展,总结了典型高功率微波武器装备的性能特点,并分析了其发展趋势。     

Rounded Corners in Microwave High-Power Filters and Other Components

Microwave high-power filters must be operated with internal air pressures of at least one atmosphere, or with a good vacuum. Pressures between these extremes result in reduced powerhandling ability. The breakdown processes for both high air pressure and vacuum are discussed, and it is made clear that any sharp corner on which the electric field would concentrate must be rounded if high-power operation is to be achieved. For good results in vacuum operation, the surfaces must be especially smooth and free of contamination, while in high-pressure operation, minor irregularities are less important. Various high-power filter configurations of importance are described, and the structural corners at which electric-field concentrations occur are pointed out. A number of simplified geometries are then shown that can represent the essential portions of the practical structures with sufficient accuracy for ordinary purposes. Formulas and graphs for these simplified geometries are presented that give the ratio of the maximum electric field strength on the boundary to a uniform reference field strength at a point sufficiently removed from the corner. In some cases, the boundary curve is an approximation to a circular arc, while in other cases a boundary shape is derived such that the electric field strength along the curve is constant. These constant-field-strength boundaries are optimum shapes from the standpoint of power-handling ability.     

High-power microwave LDMOS transistors for wireless data transmission technologies (Review)

The fields of the application, structure, fabrication, and packaging technology of high-power microwave LDMOS transistors and the main advantages of these devices were analyzed. Basic physical parameters and some technology factors were matched for optimum device operation. Solid-state microwave electronics has been actively developed for the last 10–15 years. Simultaneously with improvement of old devices, new devices and structures are actively being adopted and developed and new semiconductor materials are being commercialized. Microwave LDMOS technology is in demand in such fields as avionics, civil and military radars, repeaters, base stations of cellular communication systems, television and broadcasting transmitters, and transceivers for high-speed wireless computer networks (promising Wi-Fi and Wi-Max standards).     

Experimental investigations and numerical simulation of the electron flow shaped by Grigor’ev-Shesterkin matrix carbon field-emission cells

The results of the investigations of the electron flow in Grigor’ev-Shesterkin field-emission cathode cells intended for use in microwave tubes are presented. It is shown that it is possible to develop electron-optical systems (EOSs) with field-emission cathode matrices for O-type microwave tubes whose beam emittance is similar to the that of the EOSs with grids and hot cathodes.     

A system for precision reactive ion-beam etching of nanostructures for field-emission devices

An system for precision selective ion-beam etching of nanostructures for field-emission devices is developed. The system is equipped with a Radikal-M160 multibeam ion source with a cold cathode and closed electron drift forming the ion beam of the working substance with a diameter of 160 mm and a microwave input for the supply of the microwave bias to the treated substrates. Technological possibilities of the system are investigated experimentally. The advantages of simultaneous ion-beam and microwave etching of the nanostructures are shown. The processes of precision etching of nanostructures through a mask up to 1 μm thick with diameters of orifices of 20–30 nm (aspect ratio of the structures of the mask ∼50: 1) are carried out.     

W波段扩展互作用速调管的研究

扩展互作用速调管是在大功率速调管的基础上,采用扩展互作用谐振腔技术,扩展其瞬时工作带宽,在毫米波频段能够实现高功率、高效率、高增益和宽频带的一种紧凑型微波真空器件。本文基于空间电荷波理论对多间隙谐振腔电路进行了简要分析,采用PIC三维粒子模拟软件对高频互作用电路进行了粒子模拟与优化。在2π模式工作下,其工作电压为15 kV,电流为0.8 A,中心频率为94.5 GHz时,得到了效率大于8.4%,峰值功率超过2 kW的微波功率输出,-3 dB带宽为1 GHz,增益超过40 dB。该工作对研发高性能扩展互作用速调管,并推动其在国防安全、卫星监测、外层空间小目标跟踪、高分辨率雷达和精确气象监测等领域应用具有重要意义。     

高频钎焊在微波电子管中的应用

微波电子行波管的高频系统往往要采用结构复杂的不锈钢零件，为解决这些零件常规钎焊工艺条件下存在的润湿性差、生产周期长以及不适于批量生产的问题，本文采用了冲击镀镍-高频钎焊的新工艺。实际应用表明，采用这一工艺，不仅较好地解决了不锈钢表面的润湿问题，而且焊接过程工艺简单、快捷。这一工艺已成功应用于产品的批量生产。     

Propagation Characteristics of a High-Power Microwave in Waveguide Filled with Plasma

Analytical theory of high-power microwave propagation in waveguide filled with plasma is presented in this paper. The ponderomotive force effect of high power microwave is taken into consideration and preliminary numerical calculations are carried out, the propagation characteristics of the high-power microwave and the influence of microwave power on the distribution of plasma density are calculated and discussed.     

Ni海绵氧化物阴极制备技术改进

采用喷砂和真空蒸散技术，改进了Ni海绵氧化物阴极制备方法。试验表明，这一改进可显著提高阴极制备质量，有利于提高大功率微波器件的可靠性。     

The resistive sensor: a device for high-power microwave pulsedmeasurements

In this paper we review a novel microwave power sensor, the operation of which is based on the electron-heating effect in semiconductors. The sensor has been specifically developed for the measurement of high-power microwave pulses. The sensor's principle of operation and its related circuitry are described. The influence of lattice heating on the sensor's performance is considered. The actual design and implementation of a waveguide-type sensor is presented, including details regarding its calibration. The application of the sensor for the measurement of microwave pulses at medium and high power levels is also presented     

Amplification factor of echo signals in ferrimagnetic materials

It is known that spin echoes in ferrimagnetic materials can only be excited on the application of high-power microwave signals. The amplification factor of spin echoes is calculated for ferrimagnetic materials; long-range dipolar field, external RF-field couplings, and magnetization relaxations are included in the calculations. The inclusion of such interactions provides a mechanism by which realistic amplification of echoes may be calculable. The theoretical estimate of amplification is in reasonable agreement with previous experiments. Thus, the effects of carrier frequency, field gradient, and microwave power on echo amplification are calculated     

Innovations in microwave filters and multiplexing networks forcommunications satellite systems

The evolution of microwave filters and multiplexers for space application is described. The many advances are described within the context of the design of the overall communication subsystem. Emphasis is placed on the multipaction and passive intermodulation (PIM) considerations in designing high-power multiplexers. The impact of microwave filter technology in the channel characterization of satellite systems is described. The future directions of research and development are briefly discussed