行波管电子枪改进及过渡区磁场设计的模拟计算

分析了行波管电子枪和过渡区磁场设计的基本原理和方法,结合互作用区分别对高面积压缩比、低导流系数电子枪及其后的过渡区磁场进行改进和设计：首先对加辅助阳极的原电子枪和过渡区的周期聚焦磁场进行优化,在考虑热初速的情况下,对电子枪和磁场再度优化。模拟结果表明：辅助阳极能有效改善高面积压缩比、低导流系数电子枪产生电子注的层流性;电子热初速对电子注质量影响较大;合理的过渡区磁场能为互作用区提供符合要求的电子注。运用此设计对一螺旋线行波管进行模拟计算,达到了良好的效果。     

基于Spindt冷阴极的行波管电子枪设计

针对X波段小型化Spindt冷阴极螺旋线行波管进行了电子枪设计.基于皮尔斯型电子枪结构,联合PPM高频聚焦系统,以电子注聚焦特性为优化目标,采用CST粒子工作室对电子枪结构和工作参数进行了优化设计,获得了 30 mA工作电流下电子注填充比为0.68的良好电子注聚焦.在此电子枪结构和高频结构下,分析了特定电流下电子注聚焦...     

Computer simulation of ion trapping and detrapping in a PPM focusedtraveling wave tube

This paper presents results from a time-dependent, electrostatic electron gun simulation code, simulating ion trapping and detrapping in a traveling wave tube (TWT) focused by periodic permanent magnets (PPM). The simulations described indicate that ion loss is primarily radial through the beam tunnel walls, rather than axial through the gun or collector. The electrostatic potential well formed by the electron beam is constantly being filled by ionization of a background neutral gas. This effect constitutes the primary ion loss mechanism. Filling of the potential well is made possible by loss of the low energy electrons produced by ionization (secondary electrons) through periodic nulls in the magnetic field     

A new type of cathode-ray tube with a crossed-field gun

This paper introduces a new type of cathode-ray tube with a crossed-field electron gun which produces an electron beam in a region where a nonuniform magnetic field and an electric field cross perpendicularly. The new configuration gives increased freedom in the design of crossed-field guns. As a result, a long, directly heated cathode can be readily applied to a gun structure which makes high perveance and instant operation possible with much improved cathode heating efficiency. The new gun provides ion trap action by virtue of a magnetic field which separates ions from electrons due to the difference in their masses. A new type of cathode-ray tube using this gun not only demonstrates these features but also requires relatively low operational voltages for beam acceleration and control electrodes. The paper includes an analysis of electron motion in a crossed field with a nonuniform magnetic field. It also shows practical configuration of electrodes and current characteristics of the gun.     

场致发射阵列阴极电子枪的设计及模拟研究

讨论了微波管用电子枪的一般参数和要求，对于在微波管中应用场发射阵列阴极电子枪的情况作了分析，表明其中存在的主要问题是电子注散焦。通过比较场发射电子注聚焦的几种方法，利用传统电子枪整体聚焦的思想，初步设计了一个场发射阵列阴极电子枪模型，它包括场致发射阵列阴极，一个Whelnelt电极，一个聚焦电极和一个阳极。通过利用Mafia软件对电子注轨迹的模拟计算，对电子枪的聚焦部分进行了改进。     

碳纳米管冷阴极Pierce电子枪

为发展场致发射冷阴极毫米波电真空辐射源器件, 对利用大面积碳纳米管冷阴极产生大电流、高电流密度电子注的电子光学系统进行了研究.通过在Pierce电子枪阴极表面引入栅网结构, 解决了碳纳米管冷阴极场致发射所需的强电场和电子聚束问题.在碳纳米管冷阴极实验测试数据的基础上, 采用粒子模拟软件对上述电子光学系统进行了仿真.研究了栅网对注电流、注腰半径和电子注散射的影响, 分析了阳极电压和外加轴向磁场对电子注的聚束作用.优化后的仿真结果表明在阴极发射面为3.03 cm2时, 该电子光学系统能够产生210 mA、60 kV, 电流密度为6.7 A/cm2, 最大注半径为1mm的电子注.     

均匀磁聚焦和周期磁聚焦部分屏蔽流过渡区的设计

本文叙述均匀磁聚焦和周期磁聚焦部分屏蔽流过渡区设计的一种方法,指出对于阳极电位与慢波线电位不同的电子光学系统,以及这两个电位虽然相同,但导流系数大,阳极孔效应严重的电子光学系统,它们的过渡区的设计,必须采用非等位空间中的傍轴电子轨迹方程。并对用部分屏蔽流周期磁聚焦的电子光学系统,电子枪区中的电子轨迹与磁力线重合的问题提出一些看法。     

An Iron-Free Magnetron-Injection-Gun for a 28GHz, 200kW Gyroklystron Amplifier

A design study of a double-anode magnetron-injection-gun is performed to incorporate the electron gun into a high power 28GHz gyroklystron amplifier operating at 70kV and 8.2A. The electron gun is designed to be used in a tapered magnetic field in the cathode region produced from an iron-free superconducting magnet. An electron trajectory code predicts a beam axial velocity spread of 5.9% at α = 1.5, 70kV, 8.2A and 10.4kG, which is a high quality electron beam suitable for the high gain, high efficiency, five-cavity gyroklystron amplifier. The successful design of the high quality electron gun is attributed to a longer gap between the modulating anode and the grounded anode compared with the case of the first 28GHz electron gun built with an iron enclosed electromagnet.     

A 2-kW multioctave TWT focused with samarium cobalt magnets

The most severe and fundamental performance limitation of the PPM focused TWT has been excessive thermal heating of the RF propagating structure due to some fractional interception of the electron beam. The quality of beam focusing has largely been determined by the characteristics of permanent magnets in the Alnico series. With the introduction of the cobalt-rare earth alloys, a breakthrough in the performance of PPM focused TWTs can be expected. A samarium cobalt focused TWT yielding an output power of 2 kW at 10 percent duty is described. Utilizing a conventional helix slow-wave circuit, the tube covers a multioctave frequency range from 3.5 to 10.6 GHz. Successful operation has been achieved into a load VSWR of 10:1. The magnets are fabricated from powdered cobalt-rare earth alloys by a process sequence that includes powder preparation, magnetic alignment, pressing, sintering, and magnetizing. Energy products in excess of 15×10⁶gauss-oersteds (MGOe) have consistently been achieved for use on this tube.     

螺旋线行波管的三维互作用仿真方法研究

采用了CST工作室套装TM电磁仿真软件对一个典型的Ku波段螺旋线行波管的电子枪、磁聚焦系统、慢波结构和注一波互作用的非线性过程进行了三维的静电场、静磁场、粒子跟踪、本征模、粒子模拟的仿真和分析,得到了该行波管电子枪导流系数、慢波结构冷测特性以及输出功率和增益等参数,仿真所得数据与实测数据相符,证明了三维数值仿真全管的可行性,为后期设计和优化奠定基础。     

Design of a Large Orbit Gyrotron with a Permanent Magnet System

The paper presents results of numerical analysis and outlines the computer-aided design of a novel high-harmonic gyrotron with a beam of electrons gyrating along axis-encircling trajectories. The electron beam is formed by a novel electron-optical system (EOS) based on an electron gun of diode type with thermionic cathode and gradual reversal of the magnetic field. The results of numerical simulations predict satisfactory performance of the EOS and appropriate beam quality parameters. The tube design allows one to install different cavities optimized for excitation of TE_4,1 mode at the fourth harmonic of the cyclotron frequency or TE_3,1 mode at the third one. The target parameters of the device are: frequency about 112 GHz; output power near 1 kW and efficiency of several percent.     

毫米波带状注电子枪的设计方法

利用理论分析和仿真模拟相结合的方法对带状电子注的产生进行了系统的研究,并提出了一种带状注电子枪的设计方法.首先通过理论分析,提出了一种计算带状注电子枪结构参数的迭代算法,即根据注电压、注电流、电子注注腰处半厚度、阴极半厚度和阴极宽度,计算出带状注电子枪的阴极柱面半径、阴阳极间距、阳极柱面半径和射程等主要参数;在此基础上,通过仿真模拟,为毫米波真空电子器件设计了一种带状注电子枪.     

C波段多注速调管电子光学系统的初步设计

采用电子枪软件EGUN对C波段多注速调管的电子光学系统进行了初步设计,得到的电子枪发射电流密度均匀,电子注轨迹层流性好并且在收集极发散均匀。应用此电子枪分别研究阴极表面磁场的变化、磁场比例因子的变化、均匀区平坦度的变化对电子轨迹的影响。随着阴极表面磁场的增大,电子注注腰半径增大,电子注波动增大;而随磁场比例因子的增大,电子轨迹波动增大,波动频率增加;均匀区平坦度有波动时,磁场增大则波动减小,磁场减小则波动增大。     

W 波段回旋行波管双阳极磁控注入电子枪的设计

回旋行波管是大功率、高频率的微波毫米波器件。根据W波段回旋行波管的要求,设计了双阳级磁控注入电子枪。由电子光学理论,计算得到电子枪的初始参量,然后利用粒子模拟软件MAGIC构造电子枪模型,分析电子枪各个参数对电子注性能的影响,为电子枪设计优化提供了一定的依据。最后优化得到符合设计要求的低速度零散电子枪结构。电子枪阳极电压为70kV,电流10A,电子注速比1.07,电子注横向速度零散0.8%。     

Ka波段高压缩比电子光学系统的分析与设计

微波电真空器件向高功率、高频率、宽频带、高效率和小型化方向发展,对电子光学系统的要求也日益增高。文中设计了工作于Ka 波段的扩展互作用速调管(Extended Interaction Klystron, EIK)高压缩比电子枪,利用二维仿真软件E-GUN 和三维仿真软件Opera-3D 对轴对称电子束在均匀永磁聚焦磁场内运动状态进行建模并仿真计算。相关结果表明,在阳极电压25 kV、注电流2.5 A、阴极面电流密度不超过12A/cm2 的条件下,面压缩比约为85,电子注以良好的刚性通过互作用区域。     

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     

Effect of geometric azimuthal asymmetries of PPM stack on electronbeam characteristics [TWTs]

A three-dimensional (3-D) beam optics model has been developed using the electromagnetic particle-in-cell (PIC) code MAFIA. The model includes an electron beam with initial transverse velocity distribution focused by a periodic permanent magnet (PPM) stack. All components of the model are simulated in three dimensions, allowing several azimuthally asymmetric traveling wave tube (TWT) characteristics to be investigated for the first time. These include C-magnets, shunts and magnet misalignment and their effects on electron beam behavior. The development of the model is presented and 3-D TWT electron beam characteristics are compared in the absence of and under the influence of the azimuthally asymmetric characteristics described     

Transport of electron beams in periodic permanent-magnet focusing systems with nonharmonic distribution of the magnetic field

The results of the study of the transport of electron beams in periodic magnetic fields are presented for the case when the distribution of the magnetic field is essentially different from a sinusoidal distribution in different parts of the drift channel. An easy-to-implement nonharmonic distribution of the magnetic field is found. This distribution ensures a small ripple of the envelope of a high-intensity electron beam. The results of application of combined periodic permanent-magnet (PPM) focusing systems in high-powered pulse travelingwave tubes (TWT) are presented for the TWTs having a slow-wave structure that is superposed with the pole pieces of the PPM focusing systems.     

Simulation of the Field Emission Arrays with Parallel Wedge Emitter, Gates and Co-Planar Lens

Using the particle-in-cell (PIC) simulation code MAGIC, the wedge emitter, parallel gate and anode with and without co-planar lens have been simulated. The electron beam streamlines and the X-V_x phase space have been evaluated, which show that the co-planar lens focuses the electron. Simulation results are presented for a single FEA's cell with the anode biased at 500V and spaced 100μm from the cathode, which indicated that the electron beam width at anode is about 60.2μm for without lens FEAs, after add the lens with ?70V, the electron beam width will be decrease to 8.1μm, meanwhile the maximum transverse velocity will decrease from ±1×10⁶m/s to ±1.46×10⁵m/s.     

Experimental Analysis of Pseudospark Sourced Electron Beam

The pseudospark (PS) discharge has been shown to be a promising source of high brightness, high intensity electron beam pulses. The PS discharge sourced electron beam has potential applications in plasma filled microwave sources where normal material cathode cannot be used. Analysis of the electron beam profile has been done experimentally for different applied voltages. The investigation has been carried out at different axial and radial location inside the drift space in argon atmosphere. This paper represents experimentally found axial and radial variation of the beam current inside the drift tube of PS discharge based plasma cathode electron (PCE) gun. With the help of current density estimation the focusing and defocusing point of electron beam in axial direction can be analyzed.