关于无截获栅电子枪栅网形状的研究

本文叙述了采用三种不同形状栅网(方孔栅、六角孔栅、环形栅)的导流系数为1.4p的无截获栅栅控电子枪,在电子注分析器上进行实验的详细情况。文中扼要地介绍了无截获栅栅控枪使用三种不同栅网的设计方法,并给出了所用实验系统的结构。三种栅网的荧光屏显示和小孔扫描测试的结果表明,环形栅的电子光学性能最佳。从概念上定性地分析并讨论了环形栅优于其它栅的原因。这为今后设计无截获栅枪指出了方向。通过对多把无截获栅枪的实验研究和计算机计算,纠正了过去有关栅控枪和基础无栅枪性能上的一些概念上的错误结论。     

嵌镶式无截获栅栅控电子枪的研究

本文给出了一种无截获栅糊控电子枪模型。阴影栅被直接嵌镶在阴极面上,阴影栅采用环形椰网,在计算机辅助设计中提出了简化二维数学模型并建立了计算程序。通过对计算机计算结果的分析,提出了设计这种枪的方法。并通过设计一个导流系数为0.9P的栅控枪进行了实验验证。初步结果表明建立的计算机程序完全可以满足这一类无截获栅栅控电子枪的工程设计要求。     

Gridded electron guns for high average power

The design and performance of electron guns producing high-average-power beams which are controlled by an intercepting-type grid are described. The design consists of a modification of the design of Pierce-type electron guns to allow for the effect of grid insertion, and calculation of the amplification factors based on the potential distribution. The performance is evaluated in terms of the beam shapes and average beam powers obtainable. Measured amplification factors are compared with calculated values. Factors influencing the measured beam shapes are discussed. Trajectories of electrons emitted as secondaries from the grid and those of electrons deflected by the lens effect of the grid wires were plotted using an analog computer and electrolytic tank. The shapes and focusing properties of electron beams from similar gridded and nongridded guns are compared. Expressions relating the average beam power capability to the gun and grid dimensions are developed. The calculated average beam power capabilities are compared with measured values. Average beam power as high as 8 kw has been obtained with electron guns of a size suitable for use in X-band twt's.     

The design and performance of grid-controlled, high-perveance electron guns

The focusing electrode and a probe projecting through the cathode serve as control electrodes for the current from a convergent-beam electron gun. The principal advantage of this type of "grid" is that there is no interception of the high-current-density beam by the probe-grid. This paper presents the design procedure and experimental results for typical probe-gridded guns. The design procedure is used to obtain the desired perveance, beam diameter, and approximate laminar electron flow. The probe geometry that results in a minimum beam distortion is discussed. The range of values of amplification factor obtainable and the influence of probe geometry on this factor are discussed. The magnetic field required for focusing the beam from a probe-gridded gun is compared with that required for perfect laminar flow and for focusing the beam from a nongridded gun of similar design. An electrolytic tank in conjunction with an analog computer was used to plot electron trajectories, with the effect of space charge included, for the probe-gridded gun and a similar nongridded gun. A comparison of the electron optics of the gridded and nongridded gun is made. Electrical breakdown and beam current during the interpulse time are problems considered. Methods used to minimize electrical breakdown and interpulse beam current are presented. Several models of probe-gridded guns were constructed. The measured characteristics of these guns demonstrate that the advantages of grid control can be obtained with only a minor effect on gun perveance and beam focusing.     

无截获栅控电子枪的工艺结构设计及其阴极几何利用系数的计算方法

本文介绍了两种类型无截获栅控枪(即:单一栅和四极管型无截获栅控枪)的工艺结构设计。给出了阴栅结构设计的基本方法以及阴极几何利用系数的计算方法,从而合理地确定了最佳的网孔数、网孔尺寸和网筋宽度。本文还介绍了阴栅组件的加工方法、对栅方法。讨论了电子枪中的击穿现象。     

A theory for coupling gridded gun design with PPM focussing

This paper presents theoretical and experimental methods for the design and optimization of gridded Pierce electron guns. The design of periodic permanent magnet (PPM) focussing systems to control the nonlaminar beams originating from such grided guns is discussed. Simplified relationships are developed which directly couple the, heretofore separate, gun and PPM focusing design problems.     

无截获栅控电子枪CAD软件

主要介绍一个二维无截获栅控电子枪计算机模拟计算程序ＳＨＭＧ，及其关键数值分析模型和实验分析结果。ＳＨＭＧ计算程序用来验算已初步设计的无截获栅控电子枪，并进行优化。需要特别说明的是，ＳＨＭＧ程序是在ＳＬＡＣ电子轨迹计算程序的基础上完成的。     

FDTD方法及其在多注电子光学系统研究中的应用

采用时域有限差分(FDTD)方法对L波段100 kW多注速调管的单个电子枪进行三维模拟计算,通过设置最小网格尺寸和发射时间间隔,得出的电流和导流系数与采用EGUN等软件计算的结果相一致,通过从MAFIA中导入三维磁场数据,模拟了位于径向不同位置处电子注通道的电子轨迹,研究发现在磁场均匀性较好的情况下,位于径向不同位置处的电子轨迹相差很小,同时讨论了如何减少模拟时间的问题.本文最后计算了多个注的电子枪,求得了电流值和导流系数,从中导入数据可以分段模拟多注速调管高频互作用段的注波互作用,以及收集极区域的电子发散.     

The design and performance of a magnetron-injection gun

The space-charge flow solutions described by Kino and others in connection with the crossed-field carcinotron gun can be generalized to form the basis of a magnetron-injection gun design suitable for the production of hollow electron beams. In the first part of the paper this generalization is described. From the resulting flow it is possible to determine by an approximate method the electrodes to produce a gun of desired perveance with nearly uniform current density at the cathode. This technique has been used to design guns having ratios of cathode length to a diameter considerably greater than unity. The close agreement between the results obtained on several experimental guns and the theoretical predictions is described, along with the effect of departures from the prescribed fields given by the design method.     

Computer Simulation of Axis-Encircling Beams Generated by an Electron Gun with a Permanent Magnet System

Results from computer aided design of a novel electron gun generating axis-encircling beams are presented and discussed. Numerical experiments were performed by the new version of the software package GUN-MIG named GUN-MIG/CUSP. It is based on a self-consistent relativistic model and is developed as a problem oriented tool for analysis of electron-optical systems with magnetron injection guns (MIG) and electron guns with field reversal (cusp guns), forming axis-encircling beams. As a result of the simulations an electron-optical design of a novel electron gun with permanent magnet system was accomplished. The gun is expected to form high quality beams with small velocity spread and beam ripple. Parameters of the generated beams are appropriate for a prospective weakly relativistic high harmonic large orbit gyrotron (LOG). The development of such device is in progress now at the Research Center for Development of Far-Infrared Region (FIR Center) at Fukui University.     

大功率行波管无截获栅控枪的设计

根据栅控枪的基本设计原理和整管的应用要求，设计了一种高导流系数、高压缩比和高直流工作电压的无截获栅控枪。详细地讨论了无截获栅控电子枪设计方案的选择和参数的确定。设计数据和试验结果十分吻合，并给出了在Ｘ波段大功率耦合腔行波管中的应用结果。     

Gridded Electron Guns and Modulation of Intense Beams

Gridded guns are useful for producing modulated electron beams. This modulation is generally limited to simple gating of the beam but may be used to apply structure to the beam pulse shape. In intense beams, this structure spawns space-charge waves whose dynamics depend in part on the relative strengths of the velocity and density variations which comprise the initial current modulation. In this paper, the strengths of beam current and velocity modulation produced in a gridded electron gun are calculated, and it is shown that under normal conditions, the initial modulation is dominated by density variation rather than velocity variation     

Design and Field Emission Test of Carbon Nanotube Pasted Cathodes for Traveling-Wave Tube Applications

This paper presents results of computational and experimental studies of carbon nanotube (CNT) cathodes in gridded focusing guns intended for traveling-wave tube applications. With a curved CNT cathode, a cold beam emission of 11 mA was observed in a diode configuration. Two gridded focusing cathodes pasted with CNTs were then fabricated. When the applied cathode voltage was -0.86 kV, both grid and anode were at ground potential, and the cathode-to-grid distance was 200 mum, the dc emission current from the first gridded CNT cathode was measured to be 4.2 mA. The triode field emission characteristics with two accelerating stages in pulse operation were also examined. With the cathode voltage at -4 kV, a cathode-grid potential difference of 1.38 kV, and a pulsewidth of 20 mus, the measured pulsed current emission was 4.6 mA. The measured current was found to agree with MAGIC2D simulation results. Furthermore, by configuring a double-gridded focusing gun, a significant improvement in the beam focusing data collected through computer modeling was seen     

Transport of noise fluctuations in convergent flow crossed-field electron guns

The transport of noise fluctuations in convergent flow or so-called Kino-type crossed-field electron guns is investigated in terms of a two-dimensional computer simulation of the gun by the well-known Monte Carlo method for studying stochastic processes. The exact electrode configurations are simulated in the computer memory. After sufficient time has elapsed for the electron flow to achieve a steady-state condition 2000 additional time intervals are computed and then a statistical analysis is made of the fluctuation quantities. Six emission spots are considered on a finite-width cathode. The analysis is facilitated by the development of a rapid method for the solution of Poisson's equation (two-dimensional). Of particular interest in the results is the improved laminarity of the flow in the KG-M gun and the fact that there is significant space-charge smoothing throughout the gun region in both Kino-type guns. Of greater significance and as yet not explainable is the fact that Ψ versus ωct has local peaks when the space-charge density, which is spatially varying, passes through the Brillouin value (ω_{p}-ω_{c}for this condition). This knowledge could be profitably used in deciding on the location of the gun exit plane. The fact that the laminarity of the flow is sensitive to slight changes in the electric field near the cathode indicates that an absolute evaluation of the noise performance of KG-A and KG-M guns is difficult and may only be obtained through appropriate experiments.     

栅控电子枪理论新探

本文主要是利用电子光学静电透镜原理，研究栅网对栅控电子枪的影响，以及如何消除这种影响。结果表明，理论分析的结果与实验相符，对实际栅控电子枪的设计具有一定的指导意义。     

Characteristics of large-area filamentary guns used for the E-beam stabilization of gas lasers

The development of high-energy electric-discharge lasers has created the requirement for high-voltage large-area uniform-current-density electron beams. This paper describes the characteristics for a class of filamentary electron guns of novel electrode configuration that satisfies these requirements. Expressions are derived for the gun potentials, electric fields, and space-charge-limited current densities. A comparison is made between theoretical and experimental results for a low-voltage model gun. The operating characteristics for large-area high-voltage guns are also discussed.     

The.assessment of relative electron gun performance The assessment of relative electron gun performance Comments on the paper entitled “ Digital computer studies of electron guns for electron microscopes “†

A method of comparing the basic performance of electron guns is described. The method is applied to some recently computed results on two versions of an electron gun which has a hairpin-filament cathode.     

A design method for crossed-field electron guns

A design method for crossed-field guns based on a space-charge-flow solution in crossed fields is given. By using the method of analytic continuation in the complex plane, it is shown that it is possible to find the exact form of the electrodes required The design results in a gun similar to the French "short gun" with the great advantage that the current emitted from the gun and the current density at the cathode can be predicted. It is also shown that by making certain approximations to the exact space-charge-flow solution, a new type of gun can be designed, a "long gun" which can have extremely high convergence. The theory for this latter gun is extremely simple and the electrode shapes can be given entirely in analytic form.     

Theory of cathode trajectory characterization by canonical mapping transformation

The paraxial lens theory cannot directly be applied to the cathode trajectories inside the gun. This inconvenience makes the interpretation of cathode trajectories difficult since one cannot use the physical concepts familiar in the paraxial lens theory, such as focal length and magnification factor. We have proposed the canonical mapping transformation (CMT) to describe the electron trajectories inside the gun by relating the ray conditions on the cathode surface to those in the crossover plane. The method takes as variables the distance along the surface and the sine of the ray angle with respect to the surface normal to define ray conditions. It has been shown that the CMT can be characterized by a small number of optical parameters. One of the parameters is the 'electron gun focal length', an extension of the image side focal length in the paraxial lens theory. The crossover size of a triode gun can be calculated from the electron gun focal length and the initial transverse energy spread. The calculation predicts the dependence of the crossover size on the grid voltage due to the change in the electron gun focal length. The prediction is compared with the measurement and shows good agreement with it. Since the CMT optical parameters can be calculated from the representative trajectories only and as they predict practically all the necessary source properties of guns, the CMT can be used as a practical tool in the designing of various types of electron guns.     

Design of hollow and strip beam guns

This paper covers a study of strip and hollow beam guns. An automatic electron trajectory tracer has been used to study the properties of the slit-anode lens common to these types of guns. A thin beam approximation was made so that a flat-bottom electrolytic tank could be used. The results of this study have been incorporated into gun design charts. Eight hollow beam guns have been built and tested experimentally. The experimental data of these guns compare favorably with the data obtained from the anode-lens study. The limitation of thermal velocities on the maximum area compression of strip and hollow beam guns is discussed. The experimental results of a focusing scheme which uses a uniform magnetic field to focus a hollow beam down concentric drift tubes are discussed.