电子束淬火

电子束技术已广泛地应用于熔炼、焊接和金属加工。由于电子束的总效率高和定向性强,用于热处理时可以对其他热处理方法不能处理的零件进行处理。但这种方法的生产成本目前还较高,所以还很少用于生产实际。电子束加热淬火原理电子束是一种高能量的电子流。这种高能电子流是通过直热式阴极(钽)在电子枪内产生的。由电子枪喷出的电子再通过环状阳极加速射向工件。当电子束撞击金属零件表面时,电子的动能转换为热能,便使其加热。     

电子枪三维模型设计与分析

分析了电子柬轰击炉电子枪的工作原理。利用SolidWorks软件建立了电子束轰击炉电子枪的三维模型，并通过对实体模型进行干涉检查、数据测量等分析，来模拟电子束轰击炉电子枪的实际工作情况。     

基于激光加热阴极的高精密焊接电子枪研究

高精密焊接对电子枪的束流品质提出极高的要求,而传统电子枪由于工作原理的问题,束流品质的提升十分有限。探索性地进行激光加热阴极电子枪的研究,有效避免灯丝电流磁场对电子束束流分布的影响,所获得的电子枪束流能量集中,消除能量分布多峰的问题,同时由于磁场影响的消除,电子束束斑的尺寸大幅度减小。由于红外激光加热溅射效应可以忽略,阴极的寿命得到大幅度的提升。由于束流能量更加集中和斑点尺寸减小,焊接时的能量输入减小,零件的相应变形也较小。该电子枪特别适于高精密零部件焊接及需要良好束流品质热源的领域,如电子束微纳加工、高精度3D快速成形和打孔等领域。     

厚大件电子束焊接过程电子枪热防护

厚大零件电子束的焊接工业对电子束焊机的要求较高,真空电子束焊机为防止高温辐射的影响,在设计上要求电子枪的温度不得高于65℃。采用效果较好的隔热方法,将电子枪与被焊接件隔离开,从而有效控制高温辐射对电子枪的直接影响,起到良好的防护作用。采用热障涂层的方法可以实现良好的隔热效果。     

瓦里安高能加速器电子枪系统工作原理与故障维修研究

近年来,随着医疗服务水平的提高以及医疗设备的不断发展,加速器技术被广泛应用,在肿瘤疾病的治疗方面取得了很大的进展。加速器电子枪系统为加速器提供稳定可靠的加速电子束流源,是加速器重要组成部分。本文针对我院在用的瓦里安Trilogy型和21EX型高能加速器,介绍了加速器电子枪系统工作原理,并针对日常使用过程中电子枪常见故障进行研究分析,提出了一种排查瓦里安高能加速器电子枪故障的思路与方法,以及时解决故障问题。减少了因加速器电子枪故障引起的停机时间和维护费用,提高了加速器整机工作效率,确保临床工作的正常开展,提升了患者满意度。     

电子束焊机系统研究

介绍了电子束焊接的工作原理及电子柬焊机控制系统的技术要求利用计算机控制技术和PLC技术,实现了参数控制和主机系统的控制.根据电子枪的结构和性能,对电子枪中的阴极、灯丝和电子枪主要特性参数进行了研究和设计.     

计算机加强了电子束表面淬火

电子束表面淬火工艺的热源是一束从电子枪射出的高能电子,该电子枪与电子束焊机的电子枪相同,由高速微型计算机控制。电子束逐点跟踪光栅格子在几微秒时间内传递每一点所需要的能量。热处理在50～100μm压力下进行,不需要扩散泵。真空室保持部件清洁,部件是自淬的,自淬有许多优点,包括淬火速度快。钢的     

一种用于飞行时间质谱的激光光电子枪

基于光电效应原理.我们设计了一个新型脉冲激光光电子枪,它可以作为飞行时间质谱的电子碰撞电离的电离源。考察了这个电子枪产生电子束的密度与激光能量的关系,发现控制激光的能量,可以在4个量级范围内调节电子束的强度。这个电子束的脉宽与激光的脉竞相当,电子束的电流比一般热阴极电子束高几个量级,因此电高效率很高,是飞行时间质谱仪的一个理想的电离手段。最后介绍了这个电子束在惰性气体高价离子的产生方面及混合气体的分析方面的应用。     

TC18钛合金高压气瓶电子束焊接研究

研究了TC18钛合金高压气瓶电子束焊接技术,通过对原材料理化分析,制定电子束焊接工艺,对焊接接头进行X射线探伤及拉伸检测。结合电子束焊接的特点,分析了常见典型问题,对后续产品焊接工艺有指导意义和参考价值。     

用于微电子材料快速处理的新型大面积电子束的研制

本文报导了一种新型电子束源的研究结果。这种电子枪能高效率地(70%)提供KeV的大面积(75cm~2)电子束。文中给出了电子枪的基本构造、伏安特性和束电子产生效率的计算和实测。它可用于微电子材料快速热处理。     

The preparation and X-ray microanalysis of bulk frozen hydrated vacuolate plant tissue

A series of modifications have been devised which allow the peak to background ratio X-ray analytical method to be used more effectively to measure elemental concentrations in large vacuolate plant cells. Planar, frozen-hydrated fracture faces of bulk plant tissue are coated with a thin film of evaporated chromium, which prevents surface charging. Provided the film is sufficiently thin, c. 5–10 nm, there is no attenuation of the electron beam and only a small absorption of soft X-rays. The chromium makes a small but measurable contribution to the spectral background and suitable corrections may be made to the quantitative results. An improved back-scattered imaging system is described, which helps to overcome the problem of spurious X-ray signals from rough surfaces. The microscope column has been modified to permit a continuous readout of beam current, sensu stricta, during X-ray microanalysis and to allow rapid exchange of the electron gun assembly during low temperature operation. Calculations are given relating the size of the X-ray interactive volume to electron penetration and X-ray emission in both frozen hydrated and frozen dried cells. The problems of X-ray microanalysis are discussed in relation to the highly vacuolate cells found in most mature plant tissues and an example given of the distribution of four major cations in tobacco leaves.     

Electron gun using carbon-nanofiber field emitter

An electron gun constructed using carbon-nanofiber (CNF) emitters and an electrostatic Einzel lens system has been characterized for the development of a high-resolution x-ray source. The CNFs used were grown on tungsten and palladium tips by plasma-enhanced chemical-vapor deposition. Electron beams with the energies of 10相似文献   

使用平行束软X光透镜的深亚微米X射线光刻

使用本实验室研制的整体平行束软X光透镜作为准直器和电子枪软X光源相配,作成了平行束软X光源,用此平行束软X光源进行了深亚微米X射线光刻实验。刻出了1.0μm～0.2μm的线条。文中对实验装置和光刻结果作了简要的介绍。     

A Continuous-Wave Linear Accelerator with an Output Electron Energy of 600 keV (Average Beam Current of 50 mA)

We describe a compact continuous-wave linear accelerator for industrial applications with an output electron energy of 600 keV, average beam current of 50 mA, and average beam power of 30 kW. The electron gun, beam dynamics, accelerating structure, and the RF-system design were modeled. After manufacturing, assembling, and tuning, the accelerator was started and the design parameters were achieved.     

Thermal-structural analysis of electron gun with control grid

Steady state thermal-structural analysis of electron guns is essential due to the requirement of high reliability in beam performance. Temperatures and displacements for all the components of an electron gun with a control grid are computed. Steady-state thermal analysis has been carried out for various cathode temperatures and various intercepted powers on the control grid to determine the temperature of the control grid. These results are verified experimentally based on measured results from an assembled electron gun. Structural analysis of the electron gun is used to evaluate the deformation of the inner electrodes under the hot condition. The results show that the thermal stress slightly changes the characteristics of the gun. The obtained thermal deformation data can be helpful to modify the design dimensions and assembly of an electron gun.     

The design of an electron gun switchable between immersed and Brillouin flow

An electron gun, which can be switched from immersed flow to Brillouin flow during operation, may have advantages for charge breeders as well as for electron beam ion sources and traps (EBISTs). For EBISTs this allows to change the current density according to the repetition frequency and charge state, for charge breeders and EBISTs a lower current density in immersed flow provides higher acceptance for injected ions, while the higher current density in Brillouin flow results in shorter breeding times and a lower emittance for the extracted beam. Therefore, we have designed such a gun for an EBIS with 5 T central magnetic field and without the use of iron and moving the gun. The gun was placed in the axial fringing field of the 5 T solenoid in such a position that a gate valve can be placed between the gun and the cryostat to allow for simple maintenance. The field at the cathode surface turned out to be only 0.05 T, which is not enough to focus 50 A∕cm(2) at a few kV. However, if a small normal conducting solenoid is placed over the vacuum tube in position of the gun, a field of 0.1 T may be obtained. With this the use of LaB(6) as cathode material results in a magnetic compression of 44 and therewith in a focused current density in the trap region of more than 2000 A∕cm(2). By reversing the current in the gun solenoid the cathode field can easily compensated to zero. By proper design of the electrodes and the compression region, the gun will be able to deliver a beam in Brillouin flow. While this is interesting by itself--remember the "super-compression" reported on CRYEBIS-I--any magnetic field between zero and the value for immersed flow will result in an electron beam with a wide range of adjustable high current densities. The design tools used have been INTMAG(C) for the calculation of magnetic fields, EGN2(C) for the simulation of the gun and ANALYSE(C) for detailed analysis of the results (for more information see www.egun-igun.com).     

Generation of narrow focused beams in a plasma-cathode electron gun

The possibility of generating a narrow focused electron beam in a plasma-cathode electron gun has been studied. An operating mode in which the emitting plasma surface is deep in the emitting channel is optimal for obtaining the highest emission-current density. The beam diameter is reduced by a factor of 1.5–2.0 by choosing the operating mode of the plasma emitter. A two-lens focusing system is used to focus the electron beam. Studies have shown the possibility of generating beams with a power density five to seven times higher than that attained earlier in plasma-cathode guns. As a result of these studies, a plasma-cathode electron gun that allows generation of an electron beam with a diameter of ～260 μm and a power of 3 kW at an accelerating voltage of 30 kV has been developed.     

GH99镍基合金薄板电子束焊接头疲劳性能研究

电子束焊作为一种先进的连接技术,具有能量集中、焊接速度快、热影响区小等特点,被广泛应用于工业工程、航空航天等国民经济的重要领域。随着航天飞行器发动机设计寿命的不断提高,主要结构部件的电子束焊接头疲劳性能越来越受到设计工作者的关注,研究电子束焊接头的疲劳性能已经成为焊接工作者一个重要的课题。本文采用电子束焊接工艺,制备了GH99镍基高温合金薄板对接接头。针对电子束焊接头,进行了显微硬度测试、疲劳性能的研究及疲劳失效机理分析。研究表明,电子束焊接头焊缝中心及热影响区的维氏硬度与GH99镍基高温合金母材金属基本相同,接头并未出现性能的不均匀性。对两种工艺下的电子束焊接头的疲劳S-N曲线分析表明,适当加大电子束焊焊接电流,有利于减少焊缝焊根部位的焊接缺陷,有利于提高电子束焊接头的疲劳性能,从而提高了焊接接头疲劳寿命。     

The selection of conditions for examination of specimens in a scanning electron microscope

In the past not much attention has been paid to the use of the most desirable conditions for examining a particular kind of specimen in a scanning electron microscope (SEM). The various factors affecting resolution in the SEM, namely those of beam diameter, beam penetration, contrast, signal-to-noise ratio and depth of focus, are examined. It is not possible in practice to eliminate all detrimental effects and compromises have to be made in instrumental settings, such as gun potential, lens currents, etc. in order to obtain the best image for a given specimen. This paper deals with the problems involved in examining textile fibres, metal surfaces and thin films with particular emphasis being made on the choice of gun potential and the amount of image detail observed. Examples are shown comparing micrographs taken using gun potentials of 5 kV and 20 kV, showing that due to electron-penetration effects much surface detail is lost at the high gun potential. It is, therefore, useful to examine specimens initially at different accelerating voltages to determine if any desirable information is being lost due to the penetration of the electron beam. Some operating conditions are also given for use as a guideline for working at low accelerating voltages.