Analysis on electrostatic pattern yoke camera tubes

To investigate the features of electron-beam systems in electrostatic deflecting camera tubes, a method for calculating the deflection field of the twisted curved-arrow pattern yoke is presented using the method of separation of variables. In spite of three-dimensional analysis, field values at 2000 points can be calculated at 10^-3accuracy within 1 min using a HITAC-M200H computer. Distributions of deflection field also are given. Furthermore, deflection aberrations of electron beams are analyzed in the magnetic focusing and electrostatic deflecting (MS) systems. It is revealed that the favorable features of MS beam systems can be realized only by utilizing a nonuniform magnetic field. It is also seen that deflection aberrations and landing error are very dependent on a twist in the pattern yoke.     

Electrostatic deflection yokes

A number of specific examples of a certain class of electrostatic deflection yokes, here called pattern yokes, have been described in the literature by Gray [1] and Schlesinger [2]. In this paper a theoretical procedure is presented that permits the determination of the potential distribution as well as the deflecting properties of these yokes. The method is illustrated on Schlesinger's curved-arrow pattern yoke and a modification of that yoke. The general nature of the deflecting, distorting, and defocusing properties of such yokes is discussed.     

Sensitivity of Crosstalk in Twisted-Pair Circuits to Line Twist

The prediction of crosstalk induced in an unbalanced twisted pair by an adjacent transmission line is investigated. The induced voltage at one end of the twisted pair is shown, experimentally, to be extremely sensitive to twist for low-impedance loads and relatively insensitive to twist for high-impedance loads. Ex- perimental results are given which show that a slight rotation of one end of the twisted pair ( no more than 1800) can cause a change of as much as 35 dB in the induced voltage. The consequence of these results is that, in a practical situation, one would therefore not be able to predict this crosstalk for low-impedance loads with any con- sistency. A simple model explaining these results is given.     

扭曲多高斯光束在梯度折射率光纤中的传输特性

为了得到一种新型椭圆扭曲多高斯-谢尔模(TMGSM)光束, 采用Mercer模式展开的方法进行了理论分析和验证, 证明了多高斯-谢尔模关联结构可携带扭曲相位, 详细研究了其在梯度折射率光纤中传输时的光强和相干度演化。结果表明, 椭圆TMGSM光束在梯度折射率光纤中传输时, 光强和相干度分布随着传输距离的增加发生周期性旋转, 并在0.5L(L为周期)的整数倍处偏转π/2, 其旋转角速度呈非线性变化且与扭曲因子的大小有关; 增大多高斯模数, 焦平面处光强分布的平顶区域增大, 相干度分布轮廓变小。此研究结果在光纤通信、聚焦成像、光学捕获等方面具有潜在的应用前景。     

新型长周期光纤光栅的扭曲特性研究

发现高频CO2激光脉冲写入的长周期光纤光栅（LPFG）具有独特的扭曲特性：1）扭曲特性具有明硅的扭曲方向相关性——顺时针扭曲时谐振波长发生“红”移，逆时针扭曲时谐振波长发生“蓝”移，无论顺时针还是逆时针扭曲损耗峰幅值都近似线性减小；2）若被扭曲的光纤比被扭曲的长周期光纤光栅长得多，则扭曲时长周期光纤光栅谐振波长和幅值的变化出现周期性的起伏。利用扭曲光栅引起椭圆双折射进而导致偏振态变化的相关理论合理解释了这些独特的扭曲特性。     

磁偏转线圈的优化设计

本文由谢志行等(1987)给出的场参数表达式,借助正交设计法,对带屏蔽筒鞍形偏转线圈进行了优化设计,所得结果与实际模型相符。指出了鞍形偏转线圈的端耳效应和场参数B0(z)分布对象差的重要贡献。例示了有限长余弦分布绕组与分布式绕组之间电子光学性能的比较。     

A mixed-field type of Vidicon

A new type of Vidicon has been developed which uses magnetic focus and electrostatic deflection. Since both fields are superimposed in the same space, Focus Projection and Scanning (FPS) is accomplished simultaneously. In this way, Vidicon tubes of very compact size can be realized (typically a format of 1 inch by 4½ inches overall). The electron optics of this FPS system is outlined. It is demagnifying and yields excellent landing and edge-focus performance. Signal output is high (0.5 µA), and resolution in excess of 800 TV lines has been realized in a 1-inch envelope with 350 volts as the highest voltage. For a tube of given size, various performance factors such as resolution, shading, and deflection sensitivity can be balanced by design such as to enhance some factors at the expense of others. This mutual interdependence is briefly discussed. It is also shown that the ceiling of performance for this combination of crossed fields is inherently higher than for similar devices using sequential, rather than simultaneous, focusing and deflection.     

提高9″显象管边缘分辨率的实验研究

本文从分析9″显象管电子枪的结构特点出发,讨论了影响荧光屏上电子束光点尺寸的三个主要因素:透镜放大率、球面象差和空间电荷效应。提出了用减小调制极孔径,增大调制极与加速极之间的距离等方法来减小电子束最小交叉截面的尺寸和电子束的发散张角;并且以调整电子枪在显象管内的位置,即增大它与偏转线圈之间的相对距离,来减小偏转线圈杂散磁场所引起的偏转散焦;从而有效地改善了整管的聚焦性能,并明显地提高了边缘部分的分辨率。 试验结果和批量生产的管子测试表明:上述方法是卓有成效的,其边缘分辨率能提高50线以上。     

Theory of signal light amplification by stimulated Raman scattering in twisted single-mode optical fibers

Characteristics of signal light amplification by stimulated Raman scattering are studied theoretically for the twisted single-mode fibers. Coupling equations for orthogonal modes in the fiber are derived and solved analytically. The optical gain dependence on fiber twist rate, fiber length, and so on are numerically investigated. The Raman gain for the twisted fiber with a rate of 1 turn/m is found to be reduced by 10 dB comparing with the nontwisted fiber for the fiber length less than 2 km, while it is almost independent of twist rate for the fiber longer than 10 km.     

磁滞损耗的热分布计算

本文对偏转系统的能量损耗进行了分析.磁滞损耗是在偏转条件下偏转磁芯能量损耗的主要部分,应用商用EMAS、NASTRAN软件和开发的DUEMAS可以进行磁滞损耗和热分布计算.本文对计算的方法和磁滞损耗产生的热分布进行了介绍.     

A new approach to kinescope beam convergence

Misconvergence of the beams in color kinescopes because of deflection has been corrected in the past by the use of dynamic convergence devices. Six independent fields are required to deflect three beams without misconvergence. Conventional deflection yokes supply two of these fields; the remaining four are supplied by convergence magnets. This paper describes a more general system that uses six coexistent deflection fields. Such a system is capable of producing deflection without misconvergence, and in contrast to conventional systems produces no loss in color purity tolerance. A particular embodiment of this system is discussed in detail. It employs a six-coil "converger" used in combination with a conventional deflection yoke. The results of an experimental investigation of this embodiment are given.     

Observations of a bistable twisted nematic liquid-crystal effect

In nematic liquid-crystal layers with a π/2 twist, reverse twist disclination lines occur which can be pinned by surface features and moved by electric fields. We consider these effects as the basis of a bistable matrix display. The optical transmission through twisted regions of opposite chirality is analyzed using a Poincaré sphere construction.     

楔形偏转线圈和平板电极静电偏转器的偏转场的计算方法

本文介绍楔形截面的偏转线圈和平板电极的静电偏转器的偏转场的计算方法。楔形线圈可以组合成形状多样的组合磁偏转器,有利于通过适当改变场分布形状,进一步减小偏转象差。矩形平板电极静电偏转器的优点是结构简单,有希望用它组成多电子束系统的偏转器阵列。根据上述两种偏转器的计算方法,已建立起实用的计算机程序,计算了一些典型结构偏转器的场分布。     

OPTIMIZATION OF THE MAGNETIC DEFLECTION SYSTEM BY THE METHOD OF ORTHOGONAL DESIGN

By using the expressions of the field parameters and with the aid of the Orthogonal DesignMethod,we optimized the design of the saddle delection yoke with a ferromagnetic shield.The results ob-tained agree with the practical model.It is pointed out that the end ear and the distribution of the fieldparameter B_0(z)have important effects on the deflection aberrations.An example is given,in which the elec-tron optical properties of the deflection coils having cosine distribution and finite length and that of the de-flection coils having distributed winding are compared.     

Control and elimination of disclinations in twisted nematic liquid-crystal displays

A method for controlling and eliminating reverse-twist and reverse-tilt disclinations in twisted nematic cells without using cholesterics has been developed both theoretically and experimentally. Pretilt angle and tilting direction as well as twist angle and sense have been correlated with the appearance of disclinations. It is shown that for practical twisted nematic cells having a special sense of pretilt, the disclination free cells are realized by adopting the pretilt angle of 1°-5° and the twist angle of 80°-85°.     

Van der Waals Nanowires with Continuously Variable Interlayer Twist and Twist Homojunctions

Moiré patterns at van der Waals interfaces between twisted 2D crystals give rise to distinct optoelectronic excitations, as well as, narrowly dispersive bands responsible for correlated electron phenomena. Contrasting with the conventional, mechanically stacked planar twist moirés, recent work shows twisted van der Waals interfaces spontaneously formed in nanowires of layered crystals, where Eshelby twist due to axial screw dislocations stabilizes a chiral structure with small interlayer rotation. Here, the realization of tunable twist in germanium(II) sulfide (GeS) van der Waals nanowires is reported. Tapered nanowires host continuously variable interlayer twist. Homojunctions between dislocated (chiral) and defect-free (achiral) segments are obtained by triggering the emission of axial dislocations during growth. Measurements across such junctions, implemented here using local absorption and luminescence spectroscopy, provide a convenient tool for detecting twist effects. The results identify a versatile system for 3D twistronics, probing moiré physics, and for realizing moiré architectures without equivalent in planar systems.     

Electromagnetic Wave Propagation in Twisted Anisotropic Media

The complete solution of the differential equation describing the propagation of plane uniform TEM waves along the twist axis of a twisted anisotropic medium with a constant rate of twist is shown to be of exponential type, consisting of two identical pairs of independent propagation modes, each pair being associated with a particular direction of energy flow. Knowledge of the complete solution is used to solve the boundary value problem relative to wave penetration into a twisted medium at normal incidence, a numerical example being given illustrating the polarization transformation properties of the medium near the short wavelength limit. Analysis of mode properties reveals circnlar birefringence should occur in twisted media at long wavelengths. A link power, as shown by certain crystalline substances provided by the theory.     

CMT偏转线圈铁氧体磁芯高频磁滞回线的测量

ＣＭＴ偏转线圈铁氧体磁芯高频磁滞回线的测量对研究磁芯磁滞损耗起着重要作用,本文作了线路,测量仪器,测量方法三个方面的改进,得到了较满意的结果。     

偏转线圈在不同显像管上使用时的特性分析

文中叙述了偏转线圈光栅失真的分析方法。用此法可正确评估编转系统的性能。文中介绍了可兼容几种显像管的偏转设计方法。     

Magnetic Skyrmion Lattices in a Novel 2D-Twisted Bilayer Magnet

Magnetic skyrmions are topologically protected spin swirling vertices, which are promising in device applications due to their particle-like nature and excellent controlability. Magnetic skyrmions are extensively studied in a variety of materials and proposed to exist in the extreme 2D limit, i.e., in twisted bilayer CrI₃ (TBCI). Unfortunately, the magnetic states of TBCIs with small twist angles are disorderly distributed ferromagnetic and antiferromagnetic (AFM) domains in recent experiments, and thus the method to get rid of disorders in TBCIs is highly desirable. Here, intralayer exchange interactions up to the third nearest neighbors without empirical parameters and very accurate interlayer exchange interactions are used to study the magnetic states of TBCIs. The functions of interlayer exchange interactions obtained using first-principles calculations and stored in symmetry-adapted artificial neural networks are proposed. Based on these, the subsequent Landau–Lifshitz–Gillbert equation calculations explain the disorderly distributed FM-AFM domains in TBCIs with small twist angles and predict the orderly distributed skyrmions in TBCIs with large twist angles. This novel twisted 2D bilayer magnet can be used to design memory devices, monochromatic spin wave generators and many kinds of skyrmion lattices.