Investigation of field-emitted electron beam behaviors using a line collector in a triode electron gun system

The performance of a field-emission scanning electron microscope (SEM) is primarily dependent on the characteristics of the electron source. Field-emission electron sources provide a high current density, which can be used to produce a beam that can be focused through an electrostatic lens. Using a single 〈1 1 1〉 crystalline tungsten tip, we fabricated and tested a field emitter having a 91 nm radius and a stability under 14%. In this electron source, two electrostatic lenses consisting of 1st and 2nd anodes were designed and implemented and their performance dependence on variations in electrode shape, position, and applied voltage was investigated using a first-order finite-element method simulation. We also developed a line collector capable of measuring beam distribution and quantifying shifts in the electrical optical axis to characterize the behavior of a field-emitted electron beam as focused by an electrostatic optical system.     

The accuracy of numerical solutions for electron gun design

The solution of Poisson's equation and the equation of motion by numerical methods is discussed. By considering the truncation error due to the use of difference equations in the one-dimensional case, it is shown, on the basis of a perturbation theory, that the error in the solution is proportional to the mesh sizeh. This theory is shown to be in good agreement with numerical solutions obtained on a computer. A correction formula is then derived which makes it possible, by obtaining sointions for two different mesh sizes haand hb, to form a space-charge-flow solution accurate to second order inh. It is also shown that more accurate forms of the difference equation may be obtained to represent the steady space-charge flow. By these various means, it is possible to increase the accuracy of numerical solutions by an order of magnitude or more. Thus, by using a coarse mesh, but better accuracy, the speed of computation may be considerably increased.     

The multipactor electron gun

An electron source based on the multipactoring principle and preliminary experimental results are described. Several uses of such a gun are suggested.     

Non-adiabatic electron gun for gyrotrons

A non-adiabatic electron gun for gyrotron application is presented. Numerical investigations show some important advantages over presently used electrons guns of the magnetron type. In particular, the influence of space charge and the roughness of the emitter surface on the beam properties is significantly reduced. This allows the generation of a hollow electron beam with a low velocity spread and the operation of the gun over the full current range, almost up to the space charge limit.     

A high-resolution electron gun for thermoplastic recording using prefocus deflection

A demagnification gun of high resolution was developed for thermoplastic recording by deflecting the electron beam at the entry of a large focusing lens. The unconventional approach of prefocus deflection allows close spacing between the "short" focusing lens and the target (phosphor screen or thermoplastic tape) required for demagnification and results in a gun with a relatively short length. The diameter of the focusing lens is about three times larger than the 25-mm diameter area to be scanned in order to keep spot distortions of the deflected beam at a minimum. Electrostatic focusing combined with magnetic deflection was selected. The special focusing lens that is used is shaped for low aberrations, increased demagnification and increased deflection sensitivity. Small deflection fields are required since the electron beam is being deflected in the accelerating field while the electron velocities are still low. The gun operates at 10 kv and delivers a 5-micron spot at 1µa. This corresponds to a resolution of 5000 spot diameters at average current densities in excess of 5 amp/cm². In spite of the high resolution, the over-all length of the gun measured from the target is only 9 inches.     

电子枪理论研究的新进展

本文简要回顾了电子枪发展的历史,评述了电子枪理论研究方面的新进展,重点介绍了日本学者Fujita和Shimoyama的新近研究成果。最新的研究表明,对冷场发射和扩展的肖特基发射电子枪,存在阈值电流。当束流,Ib增大,超过阈值电流时,枪的表观亮度逐渐下降。当对整个电子光学柱体进行评价时,必须把亮度和束流的函数关系考虑在内。这时会出现关于电子枪的若干新概念。整个电子光学柱体的电子探针性质曲线由三个区域组成,即：（1）恒定束斑（d）区;（2）d∝I3/8b,妒区;（3）d∝I3/2b区。以往的理论只指出了3／8次方区的存在。3／2次方区的存在是一个新的发现。它解释了历史上曾注意到的一个事实,即当应用的束流进入μA量级时,扩展的肖特基发射和冷场发射枪的性能反而不如传统的钨丝热发射枪。     

A new electron gun for picture display with low drive signals

The paper discribes an approach to the problem of picture tube guns for small signal service. A Pierce-type cathode delivers a collimated parallel beam of 1600 microamperes at 250 volts (microperveance: 0.4). This beam is injected into a cylindrical cavity of appreciable length (3/4-inch long, 1/4-inch diameter). It is focused upon a small aperture at the far end using a parabolic axis potential. This axial focusing field is approximated by three cylinder segments at two intermediate voltages. To modulate the beam by lateral deflection, the cavity is again bisected through an axial plane and signal voltage is set up between half cylinders. This modulation by two crossed-electrostatic fields ("CFM" modulation) has been successfully applied in transistorized television, using a seven-volt video signal on a beam of 900 microamperes.     

Ring-and-line-focus electron beams from a glow-discharge gun

Electron guns have been developed in which a high-voltage cold-cathode discharge, at low pressure, generates an electron beam. By shaping the cathode, the beam may be focused in a particular contour. For example guns operating at 3kW at 15kV have been designed to focus in an annular ring or in a line.     

Multipactoring electron gun for high duty linacs

A high duty factor electron gun suitable for linac applications is described. This gun operates on the secondary emission principle to generate a pulsed, monochromatic electron output beam in excess of 20 mA average current. It has been operated at 14 percent duty factor and shows a high degree of stability and ease of control.     

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.     

A long pulse, high-current electron gun for e-beam sustained excimer lasers

A new kind of electron gun is described which has produced 5-μse-beams at 130 keV and 2 A/cm². Scaling estimates are presented which predict that this gun could operate at 400 keV and 10 A/cm², beam parameters suitable for pumping excimer laser systems. For this application the gun has the advantages that thee-beam is nearly monoenergetic and the pulse widths longer than that possible with other presently usede-guns.     

The influence of the spacings of the electron gun's triode on its characteristics

The behavior of a group of triodes of an electron gun having all the same cutoff voltage is discussed with respect to its physical dimensions. Especially the relation between gun characteristics and a design number (A, B) is investigated whereAis the distance between cathode surface and modulator and B between modulator and anode. For a fixed-grid drive pulse the total emitted cathode current and the portion of it passing through a beam-limiting aperture increases with increasingB(decreasingA) whereas the resolution decreases. If the electrical parameters like anode voltage and cut off voltage are already determined it can be concluded that there is a certain design number (A, B) for optimized beam density on a phosphor screen.     

Improved electron gun for the beam-indexing color-television display

Improved gun design has considerably increased the brightness of the 110°-25 in beam-indexing color display (triplet pitch ≈ 1.2 mm). Without dynamic correction for deflection errors the color reproduction in normal picture material is now satisfactory up to peak currents of about 2.5 mA (against 1.5 mA for the old gun).     

An improved design theory of a magnetron-injection gun

An improved design theory of a magnetron-injection gun is presented, which is based on a "constant radius" approximation. This theory derives a correction term to be added to the solution of Kino-Taylor's planar theory. It is found that, within the adopted approximation, the only correction necessary to Kino-Taylor's theory is to take into account the effect of the centrifugal force. The corrected electron trajectories and the corrected electrode shapes are shown for specific examples.     

基于仿真设计的坦克炮发射动力学研究

本文首先分析了坦克炮发射全过程动力学仿真技术,并通过运用计算机仿真技术,构建了坦克炮发生全过程的各种模型,以此为坦克炮设计人员运用计算机对坦克炮的核心心梗进行分析,就设计方案予以修改与确定,以及我国后续装甲装备的评估、论证与研制,提供了全面、科学且多元的技术途径与科学方法。     

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.