共查询到20条相似文献,搜索用时 31 毫秒
1.
A. P. Semenov 《Technical Physics》2007,52(2):276-280
A new geometrical relationship between the shape and dimensions of the cathode cavity of a reflex discharge with a cold hollow cathode is determined. The discharge characteristics and the emission properties of the discharge plasma are investigated experimentally. The conditions are determined for generating a cathode plasma that is highly inhomogeneous in the radial direction and the possibility of creating such a plasma is demonstrated. The existence of a stationary double electric layer with a potential drop of 14–16 V in the aperture of the cathode cavity is revealed. Specific features of the longitudinal extraction of plasma ions through the wall layer of the reflex and hollow cathodes are considered. 相似文献
2.
对空心阴极等离子体电子枪的理论与机理做了较详细的分析,介绍了空心阴极放电特性,论 述了激励电极和调制电极在空心阴极内等离子体形成过程中的作用,分析了等离子体中电子 和离子的运动及主要参数,推导出空心阴极内电场与电流密度的表达式,研究了形成稳定电 子束流的基本条件.利用泊松方程、电流连续性方程和运动方程对其进行了数值模拟计算, 并给出了优化结果. 在此基础上设计出了输出束流脉宽为1μs、幅值达2kA的空心阴极等离 子体电子枪.
关键词:
空心阴极
等离子体
电子枪 相似文献
3.
A. V. Karelin M. S. Stefanova P. M. Pramatarov S. I. Yakovlenko 《Applied physics. B, Lasers and optics》1993,57(4):293-300
A theoretical study of a He-Kr laser (KrII, 469.4 nm line) pumped by a helical hollow cathode discharge is presented. A detailed kinetic model of plasmachemical reactions and radiative processes including the influence of gas heating on the active medium is developed. In the process of numerical calculations the dependence of the plasma parameters (electron and gas temperature, electron and metastable density, upper and lower laser level density) and laser characteristics (output power and gain coefficient) on the variations of discharge pumping, gas-mixture partial pressures and geometry of the coil hollow cathode, are investigated. The results of the numerical calculations are in a good agreement with the experimental data. 相似文献
4.
5.
Time-and-space resolved measurements of the emission uniformity of carbon fibre cathode in high-current pulsed discharge 下载免费PDF全文
The remaining challenges, confronting high-power microwave
(HPM) sources and pulsed power generators, stimulate the
developments of robust relativistic electron beam sources. This
paper presents a carbon fibre cathode which is tested in a single
pulsed power generator. The distribution and the development of
cathode plasma are observed by time-and-space resolved diagnostics,
and the uniformity of electron beam density is checked by taking
x-ray images. A quasistationary behaviour of cathode plasma
expansion is observed. It is found that the uniformity of the
extracted electron beam is satisfactory in spite of individual
plasma jets on the cathode surface. These results show that carbon
fibre cathodes can provide a positive prospect for developing
a high-quality electron beam. 相似文献
6.
O. T. Loza 《Technical Physics》2008,53(11):1479-1484
Cold explosive emission cathodes, in which a plasma serves as an emitting surface, are used to generate relativistic electron
beams with a high current density in a magnetic field. The plasma parameters change within a microsecond, thereby significantly
changing the geometry of the electron beam. This paper is a review of techniques for stabilizing the geometry of microsecond
high-current relativistic electron beams. It is shown that only a transverse-blade explosive emission cathode in a magnetically
insulated diode can generate such beams (500 keV, 3 kA) the current density profile and electron trajectory pitch factor of
which remain constant for a microsecond. 相似文献
7.
8.
开发了氮空心阴极放电PIC/MC二维自洽模型。研究了N2传统空心阴极向微空心阴极放电转变过程中电势和电场的变化。结果表明,不同尺寸的空心阴极放电的电势及电场分布规律几乎类似,但空心阴极孔径减小且气压增加时,电场近似线性增加;典型微空心阴极电场比传统空心阴极放电电场约大3个量级;微空心阴极放电产生的电子,氮分子离子和氮原子离子的密度比传统空心阴极放电约大3个量级,且微空心阴极放电中,N2+密度比N+密度大8倍以上。 相似文献
9.
Krouchinin A.M. Sawicki A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2001,29(3):424-429
Analyzes the characteristics of rarefied, nonequilibrium-state plasmas in the internal column of a hollow cathode discharge (HCD). The analysis is based on the theory of plasma disintegration in a strong electric field (Dreicer 1959, 1960). It is demonstrated that this process has a crucial influence upon the forming of directed flux of electrons with energy values 20-30 eV at the exit of the hollow cathode. The obtained values significantly exceed the energy of thermal motion of electrons in the plasma disintegration zone. A new method is suggested of calculating electron density and electric field intensity in respect to the axis of the internal column in the channel model of the discharge. In addition, a method is presented of calculating the length of the internal column and the energy of the directed electron flux at the exit of the hollow cathode on the basis of HCD fundamental parameters 相似文献
10.
为了揭示微空心阴极放电的放电机理,利用流体模型研究了矩形微空心阴极放电的时间和空间分布特性。在氩气环境下计算得到了压强为1.3×10~4Pa时电流、电势、电场、电子和离子密度等随时间的发展变化。结果表明,整个放电过程分为四个阶段,即预放电阶段、电场由轴向向径向转换阶段、电流缓慢增长向空心阴极效应过渡阶段和稳态放电阶段。稳态放电时出现明显的空心阴极效应,阴极位降区存在很高的径向电场和较高的电子平均能量,而负辉区径向电场很弱,电子平均能量较低,电子和离子密度峰值出现在负辉区,二者数值基本相等,而在阴极位降区离子密度远高于电子密度。 相似文献
11.
采用流体模型研究了微空心阴极放电(MHCD)的特点,对放电中电场的形成,电子和离子的密度分布,电子能量分布进行了数值模拟.该计算是针对高气压,圆筒形阴极结构下的He放电.结果表明放电中存在空心阴极效应,从电子能量分布可以看出,放电中存在高能电子,放电空间的电场分布主要表现为径向电场.此外,通过改变气压,阴极孔径等参数计算出它们对放电的影响.分析表明减小孔径有利于负辉区更充分的重合.提高气压将缩短阴极位降区.
关键词:
微空心阴极放电
流体模型 相似文献
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13.
In the recent decade an RF driven, low‐pressure plasma reactor with supersonic plasma jet was developed (RPJ). This reactor was successfully used for deposition of thin films of various materials. The deposition of thin films indicates that the properties of the deposited films are dependent on the sputtering or reactive sputtering processes appearing inside the nozzle (hollow athode). The nozzle (hollow athode) fabricated of different kinds of materials and alloys works both as a cathode of the radio frequency (RF) hollow cathode discharge and as a nozzle for plasma jet channel generation as well. The RF hollow cathode discharge is a secondary discharge, which is induced by the primary RF plasma generated in the reactor chamber. The present paper deals with the experimental study of this RF hollow cathode discharge. The stress is laid on the investigation of the axial distribution of discharge parameters and sputtering processes inside the nozzle. On the base of experiments, the simple model of the axial distribution of the investigated RF hollow cathode discharge has been developed. 相似文献
14.
采用电泳沉积法、碳纳米管纸和化学气相沉积直接生长法制备了三种碳纳米管阴极. 从强流发射性能、阴极等离子体膨胀、阴极起动、发射均匀性、工作稳定性以及脉冲放气特性等多个方面, 对比研究了碳纳米管阴极和化纤天鹅绒阴极的强流发射特性, 研究表明碳纳米管阵列和碳纳米管纸阴极发射性能明显优于普通化纤天鹅绒, 碳纳米管阴极发射性能与碳纳米管取向无关, 管壁的缺陷发射对无序碳纳米管阴极强流发射具有重要贡献. 碳纳米管阴极的起动场强约为普通化纤天鹅绒的2/3, 电场上升率相同时碳纳米管阴极比化纤天鹅绒阴极起动时间短12–17 ns. 碳纳米管阴极发射均匀性优于化纤天鹅绒, 尤其是碳纳米管阵列, 整个阴极表面等离子体光斑致密且均匀. 在二极管本底气压为6×10-3 Pa时, 碳纳米管纸阴极对应的二极管峰值气压不到0.3 Pa, 约为普通化纤天鹅绒阴极的1/5, 碳纳米管阵列阴极放气量在三种阴极中最少, 仅为0.042 Pa. 结果表明, 碳纳米管阴极在强流电子束源和相关高功率微波器件领域具有潜在的应用价值. 相似文献
15.
Pitchford L.C. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1995,23(3):243-247
The emittance and brightness of the electron beam generated during the hollow cathode phase of pseudospark operation are calculated using the two-dimensional hybrid fluid-particle model previously developed to study the time and space development of the plasma in a pseudospark discharge. Two distinct energy components exist in the electron beam; a high-energy component with an energy equivalent to the full discharge voltage and another, broad, low-energy component. In the 100 ns following breakdown and for the conditions of the calculations, the emittance of the high energy component decreases by an order of magnitude and the brightness of the high energy component reaches almost 1010 A/m2 rad2. This work demonstrates the feasibility of using the model to guide the optimization of the pseudospark electron beam properties and shows that the optimum beam properties are achieved after the plasma has filled the hollow cathode and begun to expand radially in the main gap 相似文献
16.
Gastel M. Hillmann H. Muller F. Westheide J. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1995,23(3):248-253
Investigations on the electron beam current of a free running pseudospark discharge are presented. A single gap system with hollow cathodes of different dimensions is used. The filling gases are argon and helium. The electron beam signal consists of a first pulse with currents of several hundreds of mA and a main pulse with currents up to 20 A. A variation of length and diameter of the hollow cathode significantly influences the pressure range in which a free running pseudospark discharge exists and the peak current of both electron beam pulses. Plasma formation and electron beam generation are studied by high speed photography. The experimental results give some information on the discharge mechanisms that is integrated in a qualitative model of the pseudospark discharge 相似文献
17.
Multi-pulsed intense electron beam emission from velvet,carbon fibers,carbon nano-tubes and dispenser cathodes 下载免费PDF全文
XIA Lian-Sheng YANG An-Min CHEN Yi ZHANG Huang LIU Xing-Guang LI Jin JIANG Xiao-Guo ZHANG Kai-Zhi SHI Jin-Shui DENG Jian-Jun ZHANG Lin-Wen 《中国物理C(英文版)》2010,34(11):1733-1737
The experimental results of studies of four kinds of cathode emitting intense electron beams are demonstrated under multi-pulsed mode based on an experimental setup including two multi-pulse high voltage sources.The tested cathodes include velvet,carbon fibers,carbon nano-tubes(CNTs)and dispenser cathodes.The results indicate that all four are able to emit multi-pulsed beams.For velvet,carbon fiber and CNTs,the electron induced cathode plasma emission may be the main process and this means that there are differences in beam parameters from pulse to pulse.For dispenser cathodes tested in the experiment,although there is a little difference from pulse to pulse for some reason,thermal-electric field emission may be the main process. 相似文献
18.
Kirkpatrick D.A. Schoen P.E. Stockton W.B. Price R. Baral S. Kahn B.E. Schnur J.M. Levinson M. Ditchek B.M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1991,19(5):749-756
Designs, calculations, and initial data are presented from a program investigating the use of biomolecular and eutectic composite microstructures as vacuum field-emission cathodes. Calculations, supported by the initial data, indicate that these electron sources should be capable of macroscopic beam current densities, J ⩾100 A/cm2, without the formation of a surface plasma. The absence of a plasma allows these cathodes to operate as a long-pulse to DC electron sources. The designs avoid the formation of surface plasma by forcing the current emitted from the tips to transit a thin layer of silicon. The natural high-field current-limiting nature of the silicon serves to prevent the ablation of tip structures and the subsequent formation of cathode plasma. Initial data obtained with these microstructures has demonstrated Fowler-Nordheim characteristic emission. Coated bio-molecular composite cathodes have demonstrated stable DC current densities of ~100 mA/cm2, and the eutectic composite cathodes have demonstrated similarly stable DC current densities of ~1 A/cm2 相似文献
19.
The peculiarities of a magnetron discharge with a cold hollow cathode and an uncooled rod cathode are considered. It is shown that the thermionic emission of the rod cathode heated in the discharge makes a major contribution to the discharge characteristics and to the emissivity of the gas-discharge plasma and that a glow discharge can gradually change to the diffusion mode of operation of an arc discharge. Ion and electron sources with improved physical characteristics and general technical data are described. It has been demonstrated that the electrode structure of a hollow-cathode magnetron discharge holds promise not only as an emitting-plasma generator, but also as a source of atomic hydrogen and atomic flux of a consumable (sputtered and evaporated) rod cathode. 相似文献
20.
建立了空心阴极放电的二维自洽理论模型,理论研究了气压为50—120Pa,电压为150—300V的范围内Ar空心阴极放电特性、粒子密度和电离速率空间分布,特别考察了影响阴极溅射分布有关因素:阴极面上的电场、离子流和离子密度的沿阴极截面的空间分布.研究结果不仅证实了在所讨论的范围内,空心阴极效应明显存在而且发现归一化电离速率的空间分布形状强烈依赖于气压.通过研究电场、离子流和离子密度的空间分布解释了空心阴极溅射型离子激光器中不均匀阴极溅射的现象来源于阴极面附近的电场、离子流和离子密度的不均匀分布
关键词:
空心阴极放电
自洽模型
气体激光
阴极溅射 相似文献