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.     

A gun and focusing system for crossed-field traveling-wave tubes

A problem encountered in the design of crossed-field traveling-wave tubes (particularly M-type amplifiers or backward-wave oscillators) is a limitation on current due to the restricted cathode size in the usual gun systems. The scheme considered here incorporates into a crossed-field device the techniques commonly used in O-type devices for designing converging Pierce-type strip-beam guns, which can increase the effective cathode area by perhaps ten times. A design procedure is presented for getting a well-formed beam from such a gun, which is magnetically shielded, through a fringing crossed-field region into the uniform-field region of interaction. An analysis of electron flow through the fringing-field region, including the effect of space charge, is presented. A trajectory equation, solved on a digital computer, yields trajectories for the beam and design curves for various values of the important parameters. The results show the scheme to be feasible. Results are also presented from tests on an experimental, demountable tube used to test the focusing scheme. About 90 to 95 per cent of the current entering the crossed-field region could be focused to the collector, and the system behaved generally as the design predicted. An evaluation of the experimental data showed the scheme to be useful.     

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.     

A new high-performance color picture tube: The mask-focusing color tube

From a technical point of view, improvements of conventional color picture tubes could be regarded as having reached their limits. In this respect, we have found that the mask-focusing tube can achieve further improvements when combined with the black-matrix technique, a high-performance gun, dot screen structure, high-matrix transparency, and large gun electrode diameter. Two-fold improvements of brightness and contrast have been obtained with mask transparency twice that of conventional tubes, 22-percent higher matrix transparency, and mask-focusing. A 20-30 percent less deflection power has also been achieved with 110° deflection, neck diameter, and 1:2 mask-focusing voltage ratio. A 20-percent less spot diameter and a sharp beam distribution have been obtained by a new multistage-focusing electron gun in a delta arrangement in the 35.5-mm neck diameter.     

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.     

Theory of periodic electrostatic focusing of electron beams

A general theory of periodic electrostatic focusing structures in micowave tubes is presented. A general method for evaluating the properties of focusing systems is developed. The method is based on the use of the Action Function and is applicable to structures whose potential distribution can be found by the method of separable variables. It is shown that this approach can yield results similar to, but more exact, than those obtained by the classical paraxial ray equation. The basic and double-ring structures have been examined in detail. Parameters describing these structures are presented in graphical and tabular form. It is shown that for irrotational flow, a specific current distribution is required. The use of computer techniques for the solution of electron flow problems is discussed. A computer analysis has been developed and results obtained are discussed. The accuracy of the Action Function and the computer analyses has been verified experimentally. It has been shown that the focusing potentials predicted by the Action Function analysis are in good agreement with the experimental values. The computer analysis has also been shown to give results comparable with those obtained practically. Hollow beams of 3.85, 5.4, and 15.6 µP have been focused using the basic ring structure. In order to investigate the effect of unbalance of focusing and defocusing forces at the inner beam boundary, pinhole measurements have been made. It is shown that the ring structure focuses a hollow beam with some change in the beam cross section. The effect of the unbalance of forces is to transform the current density profile. Results indicate that the transformation is desirable since a beam of constant current density may be transformed to a distribution which approaches that required for irrotational flow.     

Astigmatic electron gun for the beam-indexing color television display

Though the beam-indexing color television display has some obvious advantages when compared with other display systems, the electron-optical demands are very high. First, these demands and the imaging system to be used are discussed. It turns out that the beam must be astigmatic to obtain optimum performance. The beam shape is prescribed by the deflection-coil design. This beam shape, giving rise to a vertically elongated spot of sufficiently small dimensions, is obtained by using an astigmatic gun of special design in combination with a simple rotation-symmetrical focusing lens. After a general discussion of the focusing properties of this combination, the intensity distributions along both the minor and the major axis of the spot on the screen are calculated and compared with experiments. The gamma of the beam current characteristic is measured as well as calculated. Its dependence on the beam current is small up to beam currents of about 3 mA. Moreover, the cathode loading is calculated as a function of the beam current. Without special means of dynamic correction, satisfactory color reproduction in normal picture material is obtained up to peak currents of 1.5 mA in 110°-25 in tubes. Higher beam currents would be attainable in the absence of a residual deflection error which causes a tilt of the spot near the corners of the screen. The structure of the picture is quite acceptable at a triplet pitch of 1.2 mm without using a lenticular screen.     

Graphical method for optimum design of periodic magnetic focusing structures

Many studies have been made concerning the theoretical features of focusing electron beams by means of permanent magnets producing periodic magnetic fields, and methods for practical design in traveling-wave tubes have been given. A new attempt to solve this problem by means of a graphical method by which the dimensions of the device can be optimized in every practical case is proposed.     

Application of a nonharmonic magnetic-field distribution for focusing of intense electron flows in magnetic periodic focusing systems

The results of theoretical and experimental investigation of focusing of intense extended electron flows in periodic magnetic fields with a nonsinusoidal distribution are presented. An easily realizable nonharmonic distribution that has three local maxima on the magnetic-field half-period and ensures small fluctuations of the boundary of an intense electron flow at high values of the field parameter is found. The results of application of magnetic periodic focusing systems (MPFSs) with the obtained distributions in pulsed traveling-wave tubes with a slow-wave structure integrated with the MPFS pole pieces are presented.     

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.     

A 240–380 GHz orotron with a double-row periodic structure and multifocal focusing spherocylindrical mirrors

The potentialilty of increasing the generation power of a 240–380 GHz orotron with a double-row periodic structure and multifocal focusing spherocylindrical mirrors of the open cavity (OC) in the range of 290–350 GHz is studied experimentally. This range is of interest due to the fact that it contains two atmospheric transparency windows at frequencies of 306 (λ = 0.98 mm) and 341 GHz (λ = 0.88 mm).     

G波段行波管电子枪设计与实验

设计了用于G波段行波管的聚焦极调制皮尔斯电子枪,电子注电压20 kV,电流50.9 mA,注腰半径0.056 mm,射程10.3 mm。利用热-结构耦合分析和电子注轨迹仿真方法,分析了热形变对电子枪性能造成的显著影响。为了消除电子枪热形变的影响,设计了装配模具进行补偿,并得到了实验验证。该电子枪已用于多种G波段行波管,解决了关键部件技术问题。     

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.     

W波段回旋行波管新型曲线阴极磁控注入电子枪优化设计

设计了采用新型曲线阴极结构的W波段双阳极磁控注入电子枪,手动优化得到的电子注参数在速度比1.1时,纵向速度零散为1.84%.为了克服手动优化方法的繁琐和低效,引入了数值计算方法的优化策略,编制了基于MATLAB语言的遗传算法和模拟退火算法的优化程序,并结合二维电子光学软件EGUN对该W波段曲线阴极结构电子枪进行优化,优化得到的电子枪在保证电子注速度比1.1的情况下,纵向速度零散分别达到了0.81%和1.05%.与手动优化方法相比,数值优化方法不需要设计者干预优化过程,具有自动高效的特点,且优化结果更好.     

A color separating filter integrated vidicon for frequency multiplex system single pickup tube color television camera

A new vidicon with color separating stripe filter integrated faceplate was developed for frequency multiplex system using a single pickup tube color television camera. The distinctive features of the vidicon are 1) a faceplate with integrated color separating stripe filters, 2) an indium oxide transparent electrode, and 3) a set of spatial frequency limiting quartz filters which act as a limiter for spurious color signals. A color television camera using this vidicon provided satisfactory color pictures.     

Low-voltage pseudo-differential transconductor with improved tunability-linearity trade-off

A new low-voltage pseudo-differential CMOS transconductor using transistors in the saturation region is presented. It keeps the input common-mode voltage constant, while its transconductance is easily tunable through a DC voltage preserving linearity for a moderate range of G/sub m/ values. Post-layout results for a 2.7 V-0.5 /spl mu/m CMOS design dissipating less than 1.5 mW show a 1:2 G/sub m/ tuning range with an almost constant bandwidth over 600 MHz. Total harmonic distortion figures are below -60 dB over the whole range at 10 MHz up to a 100 /spl mu/A/sub p-p/ differential output.     

Low-voltage vertical directional coupler switch with suppressedelectroabsorption

We have studied the performance of a vertical directional coupler in which a multiple quantum well and a bulk semiconductor material act as the cores of the two guides in two arms. The power output of the device is expected to be unaffected by the electroabsorption effect in a directional coupler based on quantum confined Stark effect even when operated very close to the excitonic absorption edge. The above principle is utilized in realizing low-voltage switching and almost equal power in bar and cross states in a multiple-quantum-well (MQW) vertical directional coupler. Our calculation for a vertical coupler composed of InGaAsP bulk and InGaAsP-InP MQWs show switching voltages comparable to that of a similar coupler composed of a more complex barrier reservoir and quantum well electron transfer (BRAQWET) structure, with a slightly lower value of power output     

Analysis of an azimuthally periodic vane-loaded cylindrical waveguide for a gyro-travelling-wave tube

A cylindrical waveguide, provided with wedge-shaped metal vanes projecting radially inward from the wall of the guide, excited in the transverse electric (TE) mode, was analysed. The analysis was carried out considering the angular harmonics generated by the angular positioning of the vanes. A set of equations was generated in the Fourier amplitudes of field constants. The condition for nontrivial solutions for the field constants gave the dispersion relation of the structure. From the expression of power flow down the structure, its interaction impedance was also estimated. The shape of the dispersion characteristics and the value of the cutoff frequency as well as the interaction impedance characteristics of the waveguide were found to depend on the vane parameters their number as well as their radial and angular dimensions. The optimum vane parameters were obtained corresponding to the minimum variation of the slope of the ω-β dispersion plot, such parameters being useful from the standpoint of the bandwidth of a gyro-travelling-wave tube (gyro-TWT) using a vane-loaded cylindrical waveguide as the interaction structure. The dispersion and impedance characteristics, which were found typically for the TE₀₁ mode as defined for the structure, taking four vanes, were more sensitive to the number and angular width of the vanes than to their radial depth. The value of the interaction impedance, calculated at the potential beam position, was found to be higher for a loaded waveguide than for an unloaded one, and it depended on the frequency of operation relative to the cutoff. The interaction impedance also depended on the position of the beam relative to the waveguide wall where it was estimated, and hence the optimum beam position corresponding to the maximum interaction impedance was found. The theory was validated against the dispersion characteristics reported elsewhere typically for four-vane magnetron-like structures excited in the 2π mode. Although the present study was restricted to ‘cold’ analysis of the structure in the absence of the electron beam, it could provide important feedback for analysing a gyro-TWT, using a vane-loaded cylindrical waveguide, and hence for predicting the structure parameters for the wide-band performance of the device.     

环形阴极低截止电子枪理论和模拟

提出一种新型的低截止电压环形阴极聚焦极控电子枪结构.在传统皮尔斯电子枪和杆控电子枪基础上,创新性地将球面阴极设计为环形发射区和不发射锥体区两部分,以实现更低的聚焦极截止电压,降低调制器单元的开关损耗,提升最大调制频率.研究表明,在导流系数为0.53μP的条件下,通过引入不发射锥形体,使阴极的截止电压降低一半,截止电压幅...