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...     

一维阵列电子注平面聚焦系统磁场分布特性

针对平面集成行波管对一维阵列电子注聚焦的应用需求,设计了4通道电子注平面磁聚焦系统。将各通道磁场轴向和横向分量沿轴分布特征计算结果与测试结果进行对比,确认了Opera软件计算磁场分布特征的准确性。为与轴对称周期永磁(PPM)聚焦系统电子注通道内磁场分布特性进行对比,建立了轴对称PPM聚焦系统模型,测试结果与计算结果一致性较好。通过平面聚焦系统与轴对称PPM聚焦系统电子注通道内的磁场纵向和横向分布特性对比表明,两种聚焦系统电子注通道内纵向和横向磁场具有相同的分布特征,在离轴相同位置的圆周上横向磁场分量与轴向分量的比值均为B_x/B_z≈0.11,该平面聚焦系统可实现一维阵列圆形电子注的良好聚焦。     

Equivalence of periodic magnetic field to uniform magnetic field in electron beam focusing

The general solution of the electron trajectory equation in a periodic magnetic field is derived in the form of series expansion, assuming laminar electron flow and small perturbation. It is concluded that if the cathode is not very heavily immersed in a magnetic field, beam focusing by a periodic magnetic field would be almost equivalent to that by a uniform magnetic field except near the unstable region. Under these restrictions, each focusing system would give almost the same beam ripple (in magnitude and phase) under the same injection conditions into the focusing system. It is also found that the first stable region of beam perturbation in the periodic magnetic field becomes narrower as the flux threading the cathode increases or the period of the magnetic field decreases, as far as linearization of the path equation is possible.     

Equilibrium solutions for partially immersed relativistic electron beams

The equations relating the beam radius and axial electron velocity to easily measurable external beam parameters are developed for solid, relativistic beams. The beam parameters are tunnel voltage, beam current, axial magnetic field, cathode magnetic field, tunnel radius, and cathode radius. The equations are sufficiently complex to warrant the use of a digital computer if many cases are to be evaluated. Error indicators are formulated to prevent use of the relations beyond their range of validity. The equilibrium solutions for relativistic electron beams from unshielded cathodes show that the required magnetic focusing field is lower than that computed from nonrelativistic formulas. The angular magnetic field produced by the beam itself aids in focusing the electrons. The potential depression due to space charge is analyzed. Correction curves are given which allow the use of nonrelativistic equations in predicting equilibrium behavior. The maximum possible microperveance of relativistic beams is shown to be lower than the classical value of 25.4.     

Electron beam in the presence of a periodic magnetic field with allowance for the thermal velocities of electrons

Equations are derived to study the effect of the initial transverse thermal velocities of electrons on the configuration of an intense electron beam in an electron-optical system with a significant divergence for the case of the beam focusing by a periodic magnetic field. It is demonstrated that the minimization of the effect of thermal velocities of electrons in the electron-optical system with the given level of the periodic focusing field and the cathode radius and temperature and the limiting compression of the beam in the presence of such a field is reached with the shaping systems in which an optimal magnetic flux passes through the cathode and the flux depends on the parameters of the thermal beam and the focusing field.     

A UHF traveling-wave amplifier tube employing an electrostatically focused hollow beam

The increasing importance of beam-type microwave devices has stimulated interest in focusing methods other than the usual uniform magnetic field. One such method applicable to hollow cylindrical beams, proposed by L. A. Harris, utilizes a radial electric field acting on a spinning beam to counterbalance the space-charge divergence forces. A traveling-wave amplifier operating in the 300 to 600 mc region, employing this focusing method, was designed and constructed. Experimental results obtained with this tube are presented. Beam transmissions as high as 90 per cent and net gain over 15 db were obtained. Practical considerations and tube design factors are discussed. The primary advantage of this kind of focusing is in the elimination of the solenoid, and consequent reduction in power supply requirements and weight, accessibility of rf connections to the tube, and elimination of capsule and aligning adjustments. This focusing method appears to have great potential usefulness in hollow-beam applications, and particularly in devices where the spiral motion of the beam can be made to interact with a spirally traveling wave.     

Space charge waves on an unfocused cylindrical electron beam

The effect of including the magnetic force in the dynamics of a cylindrical electron beam without the focusing magnetostatic field is discussed.     

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。     

Electron-beam flow in superimposed periodic and uniform magnetic fields

Theoretical and experimental results are presented on the focusing of an electron beam by means of a magnet structure which produces, along the axis of the beam, a periodic magnetic field superimposed on a uniform field. The relation between space-charge and magnetic-field parameters for minimum ripple is derived. The flow in superimposed uniform and periodic magnetic fields is shown to be degraded from the flow of electrons in a magnetic field which has a sinusoidal variation along the axis. The results indicate the flow conditions to be expected, where such combined fields are unavoidable. The focusing of electron beams in this type of superimposed magnetic field and in Brillouin flow are compared.     

Intense Sheet Electron Beam Transport in a Uniform Solenoidal Magnetic Field

In this paper, the transport of intense sheet electron beams in a uniform solenoidal magnetic field in high-power vacuum electronic devices is theoretically examined with the 3-D beam optics code MICHELLE. It is shown that a solenoidal magnetic field can be an effective transport mechanism for sheet electron beams, provided the beam tunnel is matched to the beam shape, and vice versa. The advantage of solenoidal magnetic field transport relative to periodic magnetic transport resides in the feasibility of transporting higher current density beams due to the higher average field strength achievable in practice and the lower susceptibility to field errors from mechanical misalignments. In addition, a solenoidally transported electron beam is not susceptible to voltage cutoff as in a periodic magnetic focusing system; hence, device efficiency is potentially higher.     

Hollow-beam focusing with electrostatic and periodic magnetic fields

A new method of focusing a hollow cylindrical electron beam is presented. The focusing system consists of a cylindrical center conductor inside the beam, a cylindrical outer conductor enclosing the beam, and a series of periodic magnets outside the tube. A radial electrostatic field between the conductors provides an outward force on the electrons. The periodic magnetic field produces an inward force on the electrons. The inward and outward forces can be adjusted to provide a balance of all the forces acting on the electrons at both boundaries of the beam by choosing the electric and magnetic fields properly. An approximate analysis has been made and is presented which gives necessary design information. A number of curves are presented which are useful in designing focusing systems of this type. Experimental results on a beam tester show that current transmission of over 90 per cent for perveance up to 11 micropervs can be obtained readily. The adjustments are not critical and the performance is very stable.     

Simulation of electron-optical forming systems with highly compressed electron beams

A method of synthesis is developed, equations are derived, and the results are obtained via this method for the simulation of systems that form high-intensity electron beams with a high compression. The relatively high compression of a beam is realized owing to both a faster (in comparison with a variation in the accompanying magnetic field) increase in the axial component of the magnetic field at a certain plane in the gun region and to selection of the length of the region in the gun where the potential increases. Electron-optical systems with beams whose structure is substantially affected by electron thermal velocities are considered. Relationships that allow determination of the initial parameters of the beam and the focusing magnetic field during the synthesis of such systems are presented.     

浸没流多透镜多注电子光学系统的模拟研究

该文采用先2维后3维的计算方法,对L波段高峰值功率多注速调管电子光学系统进行了模拟设计。采用均匀场浸没流多透镜聚焦系统对电子注进行聚焦,获得了通过率100%,填充因子55%,特性良好的旁轴电子注。模拟计算表明,多透镜系统可有效调整电子注平衡半径,电子枪区均匀场可有效调整电子注波动性及层流性,聚集系统可在阴极磁感应强度为0.001~0.01 T,主磁场为0.06~0.13 T的范围内实现对旁轴电子注的良好聚焦。     

Electron beam characteristics in radially varying periodic magnetic fields

Periodic magnetic fields are being widely used for the light-weight focusing of beams in high-power traveling-wave tubes. In many tube designs, there exists a considerable amount of radial variation in the magnetic focusing field. The effect of this radial field variation is investigated analytically as an extension of the previous work in this field. The usual design curves of α vs β are plotted with three variable parameters: ripple, cathode shielding parameterK, and radial field variation parameter x0. It is noted that it is important to keep the magnetic-field strength constant at the beam edge over a considerable variation of the magnetic-field parameter x0.     

Theory of resonant relativistic oscillator with nonuniform focusing field

The two-dimensional model of millimeter wave resonant O-type oscillator (as orotron, ledatron, resonant BWO, etc.) with a relativistic electron beam is analyzed. The selfconsistent nonlinear simultaneous equations have been obtained for the arbitrary space distribution of the magnetic guide field. The start generation characteristics are analyzed under small-signal conditions with an analytical solution taken for the case of inclined focusing magnetic field. It is found that the efficiency of electron-wave interaction appreciably depends on the focusing field strength and the relativistic mass factor. The results of numerical optimization of the guide field structure are presented to show possibility of improvement of the start characteristics of the oscillator.     

The design of periodic magnetic focusing structures

Charts are presented which facilitate the design of permanent-magnet periodic structures for focusing electron beams. These charts include curves showing the peak magnetic field required for periodic focusing in terms of the electron-beam parameters, the magnet and pole-piece dimensions required to obtain this peak field, and the resultant weight of the focusing system. Thus, sufficient information is given to design completely a periodic permanent-magnet focusing structure for a given electron beam. The design of a focusing structure for a 1-watt X-band tube is carried through in detail to exemplify use of the charts.     

Some studies on a high-perveance hollow-beam klystron

The performance of an experimental high-perveance hollow-beam klystron has been investigated. Data of small- and large-signal operation are presented in this paper. For strong magnetic confinement of the beam, it is shown that gap interaction and gain and large-signal bunching are well predictable by the appropriate theories. A sensitivity of all measurable RF-quantities to the level of the focusing field has been studied. Efficiencies are lower than predicted from the measured high degree of bunching, and reflect the effect of potential depression.     

The Magnetic Field Distributions and Beam Propagation Properties of the Hybrid Coaxial Wiggler

In this paper a novel coaxial wiggler, the hybrid coaxial wiggler, is proposed. The analytical formula for magnetic field of the wiggler is derived, and the beam propagation properties are investigated numerically. The results show that the hybrid coaxial wiggler is scalable to small periods with high field amplitude, high beam current acceptance, and excellent transverse focusing properties.