宏观尺寸弯曲石英管对中低能电子束的导向作用

研究了宏观尺寸的弯曲圆柱形石英管对 1 100, 1 300和1 500 eV 3种能量电子束的导向作用, 并对实验结果与相同材质和尺寸的直管的情形进行了分析对比。 实验中利用一个位置灵敏法拉第筒对从石英管出射的电子束进行探测, 获得从管道中出射的电子束流强度在位置灵敏法拉第筒各道上的分布, 其结果显示宏观尺寸石英管对电子束存在导向作用。 与慢速高电荷态离子和绝缘毛细管相互作用的物理过程类似, 这种导向效应是由电荷在管壁内表面自组织充电引起的。 实验还发现, 入射电子束流的强度越强, 其导向作用越明显, 这与微观尺寸毛细管对慢速高电荷态离子的导向作用不同。 石英管导向能力与管的尺寸、 形状及材料之间的关系还有待进一步的系统研究。 It was inevstigated in the experiment that the guiding effect of electron beam with energy of 1 100, 1 300 and 1 500 eV through a bended cylindrical quartz tube with macro sized. A position sensitive Faraday cup was developed and used to detect the electron beam transmitted through the quartz tube, and the distribution of transmitted beam current on each channel of the Faraday cup was acquired. Results indicate the existence of guiding effect which is due to the self organized charge up in the inner wall of the quartz tube similar to that of the highly charged ions. We also found that the guiding ability of the tube is related to the incident beam intensity. The relationship between the guiding ability and the material as well as the size of the tube is to be studied in the near future.     

强流电子束入射弯曲宏观石英管的导向效应研究

研究了强流（~129 nA）、 高能（1 500～1 900 eV）电子束在大角度(9°)弯曲宏观石英管中的导向效应。 实验分别测量了入射流强及能量对出射电子角分布值（FWHM）和传输效率的影响。 实验观察到出射电子角分布FWHM随着入射电子流强和入射电子能量增加变化均不明显; 发现电子传输效率随入射流强增加而增加, 但随入射能量增加而减小, 这与高电荷态离子导向中离子传输效率随入射能量增加而增加的现象相反。 分析发现, 与高电荷态离子导向机制不同, 电子束导向并非是由电子在石英管内壁的自组织充电过程引起的, 而是入射电子与管内壁弹性和非弹性散射碰撞共同作用的结果。 By using an incident electron beam with the high current and high energy, the guiding effect of the bended macroscopic quartz tube for the electron beam has been investigated. The angular distributions of outgoing electrons depending on the current and energy of incident electrons were measured. The dependences of electron transmitted fraction on energy and current of incident electrons are also shown. As the incident electron energy increasing, the electron transmitted fraction increases, but it decreases while the incident electron current increasing. The results have been compared with the present data. This work presents, the process of guiding electrons is essentially different from that of guiding highly charged ions, the guiding electron beam was caused by both elastic and inelastic collisions between electrons and inner walls of quartz tube, rather than self organized charging effect on the surface of inner wall of quartz tube.     

64通道一维位置灵敏电流分布探测器及其数据获取系统

针对高流强粒子束与绝缘毛细管相互作用的特点, 设计制作了一套64通道一维位置灵敏电流分布探测器及其配套的数据获取系统, 该探测器可分辨最小直径为1 mm的束斑, 通过数据获取系统可实现可视化自动数据采集。 用2 nA和200—2000 eV电子对探测器进行了定标, 并用10 μA和2000 eV的电子束穿越锥形毛细管后的出射电子, 对探测器及数据获取系统进行测试, 获得了出射粒子的位置分布谱及能量信息。 A 64 channel position sensitive current distribution detector with 1 mm position resolution was developed, while the data acquisition system is based on the LabVIEW software. The test result obtained by using a 2 nA, 200—2000 eV electron beam deflecting by different voltages and the position spectra of 10 μA, 2000 eV electrons transmitted through a glass capillary was measured. The result indicated that the detector can be used to detect the charged particles with strong beam current through the capillary.     

平行玻璃板对105 keV Ar7+离子的导向效应

研究了平行玻璃板对高流强（约80 nA）105 keV Ar7+离子的导向效应, 利用一维位置灵敏探测器测量了不同倾斜角下出射离子的强度及角分布。 实验结果表明, 平行玻璃板对Ar7+离子有导向作用。 与离子在微孔膜中的导向效应不同, 从平行玻璃板出射的Ar离子角分布的FWHM随着倾斜角的改变而改变, 并且出射离子角分布最大值处对应的观察角不等于倾斜角。 The transmission of 105 keV Ar7+ ions with high incident current (about 80 nA) through the gap formed by a paired parallel glass plates was investigated. The intensity and angular distribution of the transmitted ions for various tilt angles were measured using a one dimensional position sensitive detector. The results indicate the existence of a guiding effect when Ar7+ ions pass through the gap, but it is different from that for ions passing through nonacapillaries. We found a measurable dependence of the full width at half maximum (FWHM) of the transmitted ions as a function of the tilt angle. In addition, when the gap was tilted with respect to the direction of the incident beam, the observation angle related to the center of the transmitted ions profile was not equal to the tilt angle.     

HIRFL-CSR电子冷却束流位置测量系统

高效率的电子冷却过程, 要求电子束与离子束位置平行且重叠。 为了同时测量电子束与离子束的位置, 在HIRFL CSR电子冷却装置上研发了以容性圆筒形极板为感应电极的束流位置探测系统。 系统测量束流通过探针时产生的脉冲感应信号, 并进行傅里叶变换得到频谱信号, 分析4个不同电极上频谱信号强度获取束流的位置信息。 测量结果表明, 该束流位置探测系统测量准确, 为定量研究储存环离子累积和电子冷却过程与两种束流相对位置及角度的依赖关系提供了条件。 The efficient electron cooling requires that the ion beam and electron beam are parallel and overlapped. In order to measure the positions of ion beam and electron beam simultaneously, a beam position monitor system is developed for the HIRFL-CSR electron cooler device, which probe consists of four capacitive cylinder linear cut poles. One can get the both beam positions from the picking up signals of four poles by using Fourier transform(FFT) method. The measurement results show that the beam position monitor system is accurate. This system is suitable for investigating the relation between electron cooling processing and the angle of ion beam and electron beam.     

ECR离子源外电子注入技术研究

使用电子枪对ECR（Electron Cyclotron Resonance）等离子体注入外电子束是继铝衬弧腔、偏压盘之后,对等离子体电子的额外补充的又一种手段,通过向弧腔中注入一定能量与流强的电子束,以期提高引出束流的流强与电荷态。但由于该方法可控参数繁多,经验积累与报道资料都很少,且设计与操作远不如偏压盘等手段简便,故一直未能得到深入研究。通过以三维仿真软件CST粒子工作室对注入到弧腔电子束的运动轨迹的模拟结果为依据、以18 GHz ECR蒸发冷却源为平台,进行了ECR等离子体注入电子束的实验,结果表明:在一定实验条件下,当注入电子束能量超过1 800 eV时,会产生一种引出的离子束流的激增现象。在这个现象中,脉冲与直流的流强均比未注入电子时要高,束流电荷态向高价方向移动,且可通过控制实验条件来控制这种现象。最后对于这种电子并未通过共振面,却能起到提高电荷态与流强的作用进行了分析与讨论,并认为该现象在改善直流束与脉冲束性能的方面都有着积极的意义。The injection of the electron beam into the ECR (Electron Cyclotron Resonance)plasma by electron gun is a new method for the additional supplementary of the plasma electron, following the aluminum chamber wall and the bias plate, we are expecting for the higher current and charge state of the ion beam with it. However, because of the controllable parameter's variety, the lack of the accumulation of experience and data, and the shortage of convenience in designing and experimental practicing compared by biased disk and other means,it has always not been intensively studied. In this article, we take the 18 GHz ECR Ion Source using evaporative cooling technique as experimental platform, do the experiment of injecting electron into ECR plasma base on the simulation result of the electron beam's path in ECR's chamber by the 3D simulation software CST the particle studio. It shows that a pulsing leap of the current of the extracting ion beam appears when the injecting electron's energy is above 1 800 eV. In the mean time, the top of the pulse and the average current of the ion beam rises, the ionization state moves to a higher level. This phenomenon can be turned on and off by controlling the experimental condition. At the last part of the article, we discuss this improvement of the current and charge state of the ion beam despite of the position's missing between the injection of electron beam and the resonance surface, and hold the opinion that this phenomenon is positive to both pulsed and direct beam.     

Enhanced Current Carrying Capability of Au-ZnSe Nanowire-Au Nanostructure via High Energy Electron Irradiation

To enhance the performance of nanoelectronics based on Au-ZnSe nanowire （NW）-Au （M-S-M） nanostructure, the effect of irradiation of the high energy electron beam emitted from the electron gun of a transmission electron microscope operated at 200kV on the current carrying capability of M-S-M nanostructure is investigated in sftu. Focusing the high energy electron beam on a Au electrode, the current carrying capability of the M-S-M nanostructure can be enhanced significantly with respect to the case of the electron beam being switched off. In this case, the electrons in the electrode are excited by the incident high energy electron and can freely tunnel through the Schottky barriers at the metal-semiconductor NW （M-S） nanocontacts, which can effectively reduce Joule heat dissipation and remarkably improve the current carrying capability of M-S-M nanostructure due to the fact that the current carrying capability highly depends on the Joule heating effect of Schottky barriers at M-S nanocontacts.     

Investigation of intense sheet electron beam transport using the macroscopic cold-fluid model and the single-particle orbit theory

The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.The results indicate that the envelopes and the tilted angles of the sheet electron beam obtained by the two theories are consistent.The single-particle orbit theory is more accurate due to its treatment of the space-charge fields in a rectangular drift tube.The macroscopic cold-fluid model describes the collective transport process in order to provide detailed information about the beam dynamics,such as beam shape,density,and velocity profile.The tilt of the elliptic sheet beam in a uniform magnetic field is carefully studied and demonstrated.The results presented in this paper provide two complete theories for systemically discussing the transport of the sheet beam and are useful for understanding and guiding the practical engineering design of electron optics systems in high power vacuum electronic devices.     

Design of a high-efficiency C-band backward wave oscillator

For practicability of the high power microwave source,a C-band backward wave oscillator（BWO） which has high conversion efficiency is designed.When the axial guiding magnetic field is 0.83 T,the electron energy and the beam current of the diode are respectively 80 keV and 2.1 kA,a microwave output power of 100 MW at 7.4 GHz microwave frequency with 65% conversion efficiency is achieved in simulation.     

赝火花脉冲电子束的特征

基于电场递增效应理论,讨论了多极板赝火花脉冲电子束的特征.通过电子束对固体变色片和金属靶的轰击,对赝火花电子束的不稳定性、细丝效应和自箍缩效应等现象做了研究和分析.The characteristics of pulsed electron beam generated by multiplate pseudospark chamber (MPC) on the basis of field escalation effects have been described in this paper. The phenomena such as instability, filament effect, and self-pinch effect of pseudospark electron beam were studied and analyzedby the bombardment of solid evident films and metal targets.     

Studying the interaction of 10-keV electrons with a dielectric surface

The grazing incidence interaction of a 10-keV electron beam with a planar surface of plexiglass is studied experimentally. Moreover, the electron passage through flat channels formed by such surfaces is investigated. The experiments reveal the presence of a guiding effect of the electron passage as in the case of a glass surface. However, there are some features, such as the existence of an initial elevation angle for the case of negative inclination angles of the plate. The formation of self-consistent charge on the surface of the plexiglass and its drain when the current is turned off occur more slowly than on the glass surface. This fact points to the difference in the surface conductivity of insulators.     

电子辐照下聚合物介质内部放电模型研究

空间电子辐照环境中,聚合物介质充放电现象是威胁航天器安全的重要因素. 传统航天器介质充放电模型仅能分析材料充电过程,缺乏对放电前后介质电位残余情况与放电脉冲强弱的评估. 本文通过引入介质放电电导率,在数值积分 充电模型基础上建立同时描述航天器介质内部充电和放电过程的新模型,并将模型计算结果与实验数据进行比较,验证了所构建的模型. 模型分析结果表明,聚合物介质放电残余电位与放电电流脉冲宽度随着样品电阻率的增加而增大,放电电流强度随着临界电场强度和充电时间的增加而增强,其增幅随着辐照电子束流强度的增加而增大. 关键词： 放电模型 内部放电 电子辐照 航天器介质     

Investigation of contactless electron transmission through dielectric channels

The effect of the contactless transmission (guiding) of 10 keV electrons through cylindrical dielectric channels and planar channels formed by glass plates is studied. The capture and propagation of an electron beam along the channel axis, usual in these cases, are observed in the experiments with two plates. The deviation of the reflection angle from the specular angle and its dependence on the plate length and beamcurrent value under beam reflection from a single plate are investigated.     

Vibration transmission through plate/beam structures typical of lightweight buildings: Applicability and limitations of fundamental theories

This paper examines the modelling of vibration transmission through plate/beam structures typical of lightweight buildings. Key experiments have been carried out on simple structures to identify the applicability and limitations of fundamental theories. The systems tested included a single plate connected along its centre to a beam, two parallel plates attached along their centre to a beam (plates opposite or offset), and four plates connected along their edges to a beam. The analysis focused in particular on the applicability of modelling a beam as a one-dimensional element in point connected systems (widely spaced screws in terms of bending wavelength). Statistical energy analysis (SEA) was the framework of analysis used for all predictions, but the theories examined were independent from SEA. The results obtained indicate that simple point models are only applicable to the single plate and beam system, and to the parallel opposite plates connected along their centre to a beam; even then, the applicability of such models is limited to low and mid frequencies (below 2 kHz for the structures tested). Transmission between two parallel plates connected to a beam with screws closely spaced was also examined, and it was found that rigid and pinned line predictions can provide limits for transmission between panels on the same side of a wall (where junctions with shallow beams tend to behave rigidly, whilst junctions with deep beams are better modelled as pinned).     

Coupling Instability of a Warm Relativistic Electron Beam with Ion-Channel Guiding

In this paper, the coupling instability of warm relativistic electron beam (WREB) propagating through the ion channel guiding is investigated in detail. Obtaining the equilibrium state of the system by considering the self-electric and azimuthal magnetic field, the fluid-Maxwell equations as well as linear perturbation theory are employed to derive the dispersion relation of the excited modes in the system. Numerical analysis of the obtained dispersion relation shows that the electromagnetic (EM) instability can be induced nearly the center of the beam through coupling between the fast electron plasma wave (FEPW), originated from the longitudinal oscillation of WREB, and fast forward electromagnetic wave (FFEW). In this sense, growing the perturbation amplitude occurs due to transport the kinetic energy of WREB to the EM wave at the specific frequency range, where the phase velocity of FEPW and FFEW is coincided. The results of the present investigation will greatly contribute to the understanding of the stability of the warm relativistic electron beam in laboratory experiments, such as in free electron laser experiments, where the ion-channel guiding is used to confine the electrons against the self-repulsive forces generated by the beam itself.     

The Transverse Oscillation of Coaxial Multiple Beams Propagating along a Magnetic Field in a Vacuum Tube

A fluid Maxwell theory has been derived to study a system of multibeams propagating parallel to an applied axial magnetic field in an evacuated conducting drift tube. The stability analysis is performed for a rigid-rotor and cold-laminar flow equilibria. It is assumed that the particle beams are tenuous and the guiding field is very strong. As a result, the perturbation theory is derived under the condition that the plasma frequency is much smaller than the cyclotron frequency for each beam particle. A dispersion relation is obtained for a special case of sharp-boundary density profiles. The stability properties of infinitely long beams are illustrated in detail for different geometries and various beam parameters. The results agree with those obtained by Uhm [8] in a special case where a solid electron beam propagates through an annular electron beam. The finite geometry effect of the accelerator is discussed briefly. It might have a substantial influence on the behavior of a real device.     

Current clamping in a long pulse electron beam-gas interaction

Current clamping (constant current behavior) was observed in measurements of the current drawn by a metal plate acting as a beam collector for long-pulse (300 ns) electron beam, propagating a short distance through low-pressure gas (40-1000 mtorr). When the clamping occurs, oscillations in the beam collector current are reduced, resulting in a flat current pulse. Good agreement is found with a model which considers the impedance of the plasma produced by the electron beam in parallel with the inductance of the beam-collector current path. The current clamping occurs when the plasma impedance is smaller than the inductive impedance of the beam-collector current path