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.     

The range of magnetron injection gun parameters

Here, for the first time, the computer designs of axially symmetric magnetron injection guns are given in detail, and the practical problems of computing the electrodes are discussed. These designs have been experimentally used, showing that the design procedure is sufficiently accurate for predicting the characteristics. The important design parameters such as perveance, area convergence and magnetic field required are given for the interesting range of the normalized "computer" parameters. A method is suggested for computation of the resulting hollow beam from a truncated cone cathode, and the design of a transition region is discussed.     

Triode electron injection systems for hollow beams

Novel electron guns, in which a conical hollow electron beam is projected at a large angle to the axis into a coaxial deflection region, were tested. The guns have a triode structure so that the perveance can be varied easily. The strong deflection increases the effective perveance of the beam and makes the trajectories insensitive to current variations. In the form of a device with the gun at a large radius and projecting the beam inward, the electron paths are sensitive to scattering in the gun. The inverted gun, projecting the beam outward, is relatively free from this difficulty. The systems generally behave as expected, and should be quite useful for initiating variable-current hollow electron beams in various available focusing arrangements.     

大回旋电子枪中的CUSP磁场研究

会切(CUSP)磁场是产生大回旋空心CUSP电子注的关键,该文分别对CUSP磁场中双曲正切模式和Moster-Molnar模型进行探讨,通过理论分析和数值模拟,建立适合于大回旋器件用CUSP磁场的物理模型;并对CUSP磁场设计中的影响因数进行探讨;同时探讨了CUSP磁场与大回旋空心CUSP电子枪的关系,结果表明:改变CUSP磁场的阴极区磁场的变化对设计低速度零散、低纹波、高速度比值α的轴向环绕大轨迹CUSP电子枪有较大的影响。     

Computer experiments on electron guns

Computer techniques for analyzing an axially symmetric or two-dimensional electrode system with an emitting surface can be used to obtain cathode current density distribution, beam minimum radius and its location, as well as possible electrode current interception. Here, comparison is made of available experimental data from two axially symmetric Pierce-type guns. The choice of the two axially symmetric Pierce-type guns was made for their different value of PV/T ratio, an invariant for transverse scaling. One of them has a low ratio of PV/T(approx 0.1 times 10^{-6}), which signifies considerable beam spread due to the effects of the Maxwellian velocity distribution of the thermal electrons leaving the cathode. The other gun has a high perveance of2 times 10^{-6}, and thus relatively high PV/T ratio where beam spreading is mainly due to space-charge forces alone. Good agreement with experimental data is shown. Computer techniques of this type can be a valuable tool for diagnostic purposes of any type of space-charge-flow devices (e.g., electron guns, ion guns for space propulsion, linear accelerators, etc.) and enable the engineer-designer to arrive quickly and cheaply at an optimum configuration.     

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.     

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.     

Numerical simulation and experimental study of magnetron-injection guns for powerful short-wave gyrotrons

The results of a numerical simulation and experimental study of magnetron-injection guns forming intense helical electron beams for powerful gyrotrons are compared. Beams of three types—laminar beams, beams with regularly intersecting trajectories and beams with irregularly intersecting (mixed) trajectories are studied. The numerical simulation is performed taking into account the influence of the space charge field. The experimental beam characteristics are measured by the retarding field method. The experimental data agree satisfactorily with the results of the theory if the temperature deformation of the electrode systems is taken into account. It is shown that the best velocity distribution characteristics are realized for guns forming laminar beams and boundary beams (intermediate topology between beams with regularly intersecting trajectories and laminar beams).     

Ring-plane traveling-wave amplifier: 40 KW at 9 MM

A 9-mm traveling-wave tube (TWT) amplifier using a ring-plane circuit is described. This tube has produced a peak power of 43 kw at an efficiency of 12 per cent(2C)with a solid beam. Several guns producing solid and hollow beams have been used with comparable results at high voltages (15 to 100 kv) and low currents (0.11 to 3.8 a). A waveguide transition (special coupler) incorporating a magic tee is used to couple independently to the two modes that can exist on the slow-wave circuit. The circuits, due to their good heat dissipation capability, can be operated either pulsed or CW. Their large size (ka= 1, 2, 3 ...) with useful cross sections comparable with those of ordinary waveguides, makes them attractive for producing kilowatt powers even at much higher frequencies.     

Computer aided design of inverted strip dielectric waveguide millimeter-wave couplers

A computer aided design technique has been developed for the design of a beam splitter coupler and a distributed type coupler using inverted strip dielectric waveguides. The optical beam principle has been used for the beam splitter coupler. Numerical results for these couplers at 80 GHZ with minimum directivity of 30 dB and VSWR of 1.15 have been presented.     

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.     

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.     

Effect of electron lenses on beam noise

Some types or electron guns used to form the beam of a low-noise beam type microwave amplifier (e.g. traveling-wave tube) impress sharp potential discontinuities or velocity jumps on this beam. These discontinuities produce strong electrostatic lenses. This paper presents a theory supported by experimental results, showing that the effect of such lenses is to increase the beam noise. Further, axial magnetic fields are shown to reduce this undesirable effect.     

含多程室谐振腔的失调分析

本文给出了含多程室的谐振腔失调后的光轴确定方法，对因失调引起的衍射损耗进行了分析和近似计算。     

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。     

日立公司最新电子枪技术

对日立公司新一代彩色显像管用电子枪的结构及性能进行了剖析和系统讨论. 聚焦对比实验显示出日立公司新一代电子枪具有优越的聚焦性能.     

On grid-mesh shapes of non-intercepting gridded guns

A non-intercepting gridded gun with the perveance of 1.4μP is described. Three different gridmesh shapes (square, hexagonal and annular) are chosen, and the experimental results in an electron beam analyzer are given in detail. The design methods of the gun for each grid-mesh shape and the structures of the test system are briefly introduced. The results measured by using the fluorescent screen and pin-hole scanning technique are given. It turns out that the annular grid possessed the best electron optical performance. The reason that the performance of the annular grid is better than the others is qualitatively explained and discussed, so as to give the guide lines of how to design the non-intercepting gridded guns. Through the experiment and the computer calculation for several non-intercepting gridded guns, the previous wrong conceptional conclusions about the performances of the guns with and without grid may be corrected.     

Interaction of Two Beams with a Cavity†

Theoretical results for the small-signal interaction of two co-directed electron beams with the fields of a cavity show that, for a field that is a rectangular pulse in space and for beam transit angles less than 15 radians and beam perveances that are physically realizable with ordinary electron guns, the two-stream beam loading resistance is almost a superposition of the loading effects of the two streams considered separately, even when growing waves are present. Effects of high perveance are included in the theory which predicts a maximum in the curve of negative beam conductance versus perveance with one or two streams, when a negative conductance occurs at all. Experimental results on a tube with two hollow concentric beams confirm those theoretical predictions.     

New method of measuring the noise parameters of an electron beam

The noise figure of a microwave beam amplifier has a lower limit that depends entirely upon the noise process in the electron gun near the potential minimum. This paper is chiefly concerned with the theory and experimental results of a new method of measuring the noise parameters of the electron beam, especially the correlation between its velocity and current fluctuations, by using a "selective beam coupler" that has properties similar to the conventional microwave directional coupler. An appreciable value for the real part of the correlation coefficient between the velocity and current fluctuations was found in the space-charge-limited region. This value went to zero, or slightly negative, in the temperature-limited region. The probable error in the noise measurements is discussed by taking account of the residual selectivity of the selective beam coupler, the effect of the pickup cavities upon the beam, the thermal noise from the pickup cavities, and the higher-order modes in the beam. Measurements ofPi/S, the real part of the correlation coefficient between velocity and current fluctuations, have been made on a number of guns. Under space-charge-limited conditions, the observed values were approximately 0.2 to 0.3. Under temperature-limited conditions,Pi/S approx 0.     

动态聚焦技术及动态聚焦电子枪

截至目前，动态聚焦技术是改进大屏幕、大偏转角显像管边角分辨率和高清晰度彩色显示管分辨率均匀性的最有效方法。本文介绍与讨论了在荧光屏边缘处电子束点畸变原因以及几种典型动态聚焦电子枪的结构与性能。