电子束轰击下的试样的热效应

本文针对电子探针和透射电镜的情况,研究了电子束轰击下产生的热效应,提出了物理模型,计算了试样的温升,并用不同的实验进行了验证。在电子探针分析中,电子束轰击产生的热量可认为来源于试样中半径为r_0的半球正中,即产生于电子运动范围内,在这区域不同地方产生的热量不一样。假定在电子束半径R_0内,样品的热产生率一定,为常数a,而在R_0—r_0范围内则线性下降,即单位体积中热产生率函数:     

元件最少的自激多谐振荡器

图1是一个自激多谐振荡电路,它产生的波形如图2.这个电路元件很少,但却有着频率变化范围大、频率稳定、可取出三种不同的波形等优点. 电路工作原理为:当电源E_(bb)接通后,G_1管电流对电容器C经R_2进行充电,充电电流在R_2上产生一压降足以使得G_2管截止;随着充电电流的减小,R_2上的电压也随着减小.同时,C上电荷的积累,使G_2管的板压也随之升     

高清晰度彩色电视摄象机用的1英寸硒砷碲视象管

在以2:1隔行扫描1125行、60场/秒为基础的高清晰度电视系统中,用于实况彩色摄象的1英寸硒砷碲光导层的高分辨力电视摄象管已研制成功。利用电子束无交叉点的二极式电子枪,完全证实了硒砷碲光导靶固有的高分辨能力。由于在正偏置的G_1圆盘电极上应用了直径约为12微米的细小限束孔,所以,从平面钡浸渍钨阴极发射出的电子形成了高电流密度、低束温的狭窄层流电子束。该管具有卓越的分辨力和低的惰性,同时在宽带视频信号系统中,为了处理0.5微安标准峰值信号电流需要具有相当高信噪比的足够束电流余量。本文还讨论了是否可把这种设计概念应用到标准电视系统用管的问题。     

采用表面涂复方法改善ZnCdS荧光粉

一、引言真空荧光显示器(VFD)是一种三极管,它具有三个电极,即阴极,栅极和阳共振极。在灯丝阴极上涂有氧化钡、锶、铈。阴极加热时发射的电子被栅极和阳极的正电位加速并轰击在荧光粉上,在轰击过程中使荧光粉激发。VFD 类似于 CRT,但 VFD 的加速     

由厚靶轫致辐射确定喇曼自由电子激光器电子束的分布

本文采用测量电子轰击厚靶所产生的轫致辐射的方法来确定喇曼自由电子激光器中电子束的运动和分布规律.介绍了基本原理.给出了在激光器运转时所测得的电子束在二极管和漂移管内的运动规律和分布情况.实验结果和理论预言基本相符.     

一个扫描电镜中频闪系统

本文讨论了扫描电镜中频闪系统的设计要求和计算方法,介绍了我们的实验系统。采用高能电子束轰击InGaAs二极管,根据所产生的脉冲束感生电流信号判断已获得宽度小于5毫微秒的脉冲电子束。     

驱动感性负载的电路

在图1所示的驱动电路中,系统的控制电路可提供Vcommand信号,而Vcommand则等于所需负载电流乘以R_8°当控制电路把这个电压加在R_1上时,IC的输出电压增高,从而给Q_1和Q_2的栅极加上电压。这两个晶体管导通,从而负载电流经过Q_1和R_8流到地端。负载上的电流呈斜坡增加,而且由R_8感测的与负载电流成正比的一个电压将反馈给比较电路IC_1的反相     

新型X射线激光预电离系统

Helionetics公司的X射线激光预电离器的核心是最近研制的“电晕等离子体阴极”——种新颖的电子束源，它既有传统冷阴极的轻便性和坚固性，又具有热阴极的稳定性和长寿命。当电子束轰击高Ζ靶时产生一束强X射线束，它能透过激光谐振腔均匀地预电离高压气体。     

同轴双栅极SPINDT阴极的模拟与分析

描述了双栅极场致发射阴极的电子束聚焦问题.通过IESLORENTZ-2D 对单栅极单个SPINDT微尖的模拟,表明模拟与实验数据符合得很好.对带有同轴聚焦电极的单个SPINDT微尖也进行了模拟,并且分析了影响电子束聚焦的各种几何和电参数.结果表明,为了满足设计标准,应当同时考虑聚焦效果和发射特性.     

摄象靶的疵点

本文从理论和工艺两个方面分析摄象靶疵点(白点和黑点)产生的原因,主要是透明电极粘附的颗粒引起光导层破坏和P—N结漏电或击穿。蒸发上去的颗粒引起P—N结破坏或阻挡电子束取走信号,蒸发造成P—N结附近深陷井能级密度太高,或电阻率太低而造成高工作靶压等。减少疵点的工艺途径是提高透明电极的质量、减少肉眼看不见的那些颗粒、改进蒸发料的处理方法、改善蒸发的控制水平、尽量减少蒸发带上去的颗粒,力求降低工作靶压。文中着重对白点进行了讨论。     

碳纳米管冷阴极Pierce电子枪

为发展场致发射冷阴极毫米波电真空辐射源器件, 对利用大面积碳纳米管冷阴极产生大电流、高电流密度电子注的电子光学系统进行了研究.通过在Pierce电子枪阴极表面引入栅网结构, 解决了碳纳米管冷阴极场致发射所需的强电场和电子聚束问题.在碳纳米管冷阴极实验测试数据的基础上, 采用粒子模拟软件对上述电子光学系统进行了仿真.研究了栅网对注电流、注腰半径和电子注散射的影响, 分析了阳极电压和外加轴向磁场对电子注的聚束作用.优化后的仿真结果表明在阴极发射面为3.03 cm2时, 该电子光学系统能够产生210 mA、60 kV, 电流密度为6.7 A/cm2, 最大注半径为1mm的电子注.     

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.     

Broad-band injected-beam crossed-field amplifiers

The design and operation of injected-beam-crossed-field amplifiers, which provide efficient amplification over octave frequency bands with grid control in compact PM Focused format, are described. Dielectric supported meander lines, which are used to provide the low-dispersion and high-interaction impedance required to achieve octave bandwidth, are detailed. Relationships between space charge, gain factor, beam impedance, circuit loss, and circuit dimensions are derived for design optimization. An electron gun with a negative grid, which provides noise suppression, as well as a nonintercepting current control electrode, is shown to be effective in controlling the beam current continuously from zero to full operating value. Operating characteristics of production CFA's, providing 1 kW of average power in pulsed and CW operation and up to 5-kW peak pulsed power, are presented to illustrate the inherent multimode performance which can be achieved with low-voltage grid control.     

电荷耦合器件在电子束参数测量中的损伤问题

针对直线感应电子加速器(LIA)实验束参数测量技术应用过程中,电荷耦合器件(CCD)在纳秒激光辐照下工作的损伤效应方面进行研究。在分析CCD感光成像原理及其高能粒子测量应用的基础上,通过监测这种辐射下CCD输出信号的变化和实验后CCD的成像,对CCD中发生的软、硬损伤进行探讨,得到CCD能量损伤阈值的光子的响应特性和辐射损伤评估,保证了加速器束参数测量的可靠性。     

Highly Electron Transparent Graphene for Field Emission Triode Gates

The enhanced emission performance of a graphene/Mo hybrid gate electrode integrated into a nanocarbon field emission micro‐triode electron source is presented. Highly electron transparent gate electrodes are fabricated from chemical vapor deposited bilayer graphene transferred to Mo grids with experimental and simulated data, showing that liberated electrons efficiently traverse multi‐layer graphene membranes with transparencies in excess of 50–68%. The graphene hybrid gates are shown to reduce the gate driving voltage by 1.1 kV, whilst increasing the electron transmission efficiency of the gate electrode significantly. Integrated intensity maps show that the electron beam angular dispersion is dramatically improved (87.9°) coupled with a 63% reduction in beam diameter. Impressive temporal stability is noted (<1.0%) with surprising negligible long‐term damage to the graphene. A 34% increase in triode perveance and an amplification factor 7.6 times that of conventional refractory metal grid gate electrode‐based triodes are noted, thus demonstrating the excellent stability and suitability of graphene gates in micro‐triode electron sources.     

微波管栅发射问题的研究

利用离子束辅助沉积技术在 Mo栅极上镀上并注入一层 Hf膜,对镀后的样品进行了形貌、结构、成份、膜厚及 Mo、Hf界面分析。将样品进行电子管模拟栅发射试验,栅极温度为 650℃,试验 1000h以上基本无栅发射电流,可以提高栅控管的可靠性和寿命。实验结果表明,阴极中的活性物质Ba蒸发到镀Hf的 Mo栅极表面,Ba,Hf和O2能形成化合物,从而有效抑制栅极发射电流。     

A novel approach for focusing electron beams using low-cost ceramicgrid [field emitter arrays]

A low-cost ceramic grid was used as a stand-alone focusing electrode in field emitter arrays to obtain high brightness and small electron beam size. The ceramic grid with an array of 200-μm holes was made from DuPont 591 with low-cost equipment. Beam size is controllable by the voltage applied to the focusing grid. Light intensity profiles were measured and analyzed. The full width at half maximum (FWHM) of the light profile excited by electron emission from 30-μm wide field emitter arrays is 60 μm at 5000 V with 6 mm anode-cathode separation. At an anode voltage of 2000 V and gate voltage of 55 V, focusing is optimized at a focusing voltage of 30 V. Arc-free operation at 10 kV was achieved, thereby promoting improved phosphor efficiency. This focusing approach may lead to improve lifetimes for field emission displays and other vacuum microelectronic devices by significantly increasing the total vacuum volume and providing a means for improved getter utilization     

碳纳米管随机网络场效应晶体管电学性能分析

利用电子束蒸发技术在Si衬底形成Au电极作为底栅电极,在底栅电极上生长SiO₂薄膜。超声分散CVD法合成的商用单壁碳纳米管(SWCNTs),使用匀胶机将单壁碳纳米管悬浮液均匀旋涂于SiO₂薄膜上。再利用荫罩式电子束蒸发技术,在单壁碳纳米管随机网络薄膜表面制备漏源电极。该工艺过程避免了碳纳米管过多的化学接触,有效地保护了碳纳米管的性状。在室温条件下对器件电学性能进行测试和分析。使用该方法制备的单壁碳纳米管随机网络薄膜场效应晶体管,具有器件性能稳定、重复性和一致性较好等优点,并可用于构建碳纳米管逻辑电路。该方法对于研究基于碳纳米管的大规模、低成本的集成电路,具有较高的借鉴价值。     

栅极对电子注性能的影响分析

在三维仿真的基础上分析了无截获栅控电子枪中栅极对电子轨迹的影响因素,设计中使用非球面栅极结构的方法可有效减小因栅极的引入对电子注层流性的破坏。     

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.