可更换阴极热子的辐照加速器用电子枪

本文介绍了工作电压为60 kV、峰值电流为550-600 mA、射程要求为60 mm、注腰不大于Φ4 mm的电子枪的研制.该电子枪用于辐射加工电子直线加速器(10 MeV 1.5 mA).为降低加速器的运营成本,该电子枪特别设计为可更换阴极热子型.采用Egun、Mafia等软件进行模拟计算,基本按照速调管生产的工艺流程...     

多能量档电子直线加速器用栅控电子枪电源研究

本文介绍了一种应用于多能量档电子直线加速器栅控电子枪的专用电源。根据栅控电子枪的工作需求,电子枪的阴极处于-50 kV高压上,电源的3路输出,包括灯丝电源、偏压电源和栅控脉冲电源,均通过高压隔离变压器,将信号输送到高压端的灯丝、阴极和栅极上。利用主控计算机精确调节了电子枪发射束流的大小和脉冲宽度,以满足加速器多能量输出的需求。高压端均为无源器件,以降低故障率。此电源结构简单、调节方便、工作稳定,已在多能量档电子直线加速器上连续工作近4 a,运行状态良好。     

10 MeV辐照电子直线加速器真空系统运行情况

10MeV辐照电子直线加速器的真空系统自2004年5月安装完成后,到目前已运行8个月,其运行状况基本正常。本系统使用5台钛泵,保证达到整个加速器对真空度的要求,使加速器正常、稳定地工作。5台钛泵分别放置于波导、电子枪阴极、加速管入口、加速管出口和扫描盒处。为保证电子枪能够     

10 MeV辐照电子直线加速器真空系统改造

为达到更好的真空度,保证实验效果更佳,2005年12月对10MeV辐照电子直线加速器的真空系统进行改造。改造后,系统仍使用5台钛泵保证整个加速器对真空度的要求,使加速器正常、稳定地工作。5台钛泵位置保持不变,波导使用原钛泵,电子枪阴极处钛泵由3L/s变为8L/s,加速管入口处钛泵由2     

用于电子静电加速器的多阴极电子枪

为了延长电子静电加速器的运行周期,1973年起我们在电子静电加速器上改用多阴极电子枪。该电子枪由上海先锋电机厂制造,在一个枪体内装有4根灯丝。一根工作,另外三根备用。当工作的灯丝损坏时可方便地通过控制转换,使第二根继续工作,这就大大节省了为更换灯丝打开钢桶而花费的很多时间。本文简要叙述多阴极电子枪的结构以及在使用中的一些改进。     

电子直线加速器电子枪设计的计算机方法

本文基于Pierce电子枪理论和拉普拉斯方程的有限差分解,采用了一种新的计算机方法设计电子直线加速器电子枪。该方法包括:(1)根据设计要求确定电子枪电极。(2)对确定的电子枪进行计算机分析,计算电子束特性。该方法比常用的电解槽模拟法精度高、时间省。与一般的计算机方法相比,它基本上实现了确定电子枪电极的自动化。轴对称平行流电子枪的设计表明,即使采用较大的网格,仍有较好的精度。最后,用该法设计了4 MeV驻波加速器电子枪。     

辐照食品直线加速器电子枪设计

本文介绍了中国科技大学国家同步辐射实验室研发的一台食品辐照保鲜用直线加速器中电子枪的设计.通过枪体内电磁场模拟计算、优化电子枪形状、并且在考虑空间电荷效应情况下对电子束发射过程进行模拟,得到了满足设计要求的束斑尺寸.另外对电子枪的加工和调试过程也进行了介绍,通过电子枪高压老炼及出束实验表明,其各项参数性能均达到设计要求.另外对直线加速器螺线管聚焦线圈漏场对束流的影响也作了讨论,采用相应措施可增加磁屏蔽,减小漏场影响,保证束流品质.     

宽范围高精度电子枪系统的设计与验证

“空间环境地面模拟装置”是“十二五”国家重大科技基础设施项目,针对其子项目“低能电子加速器及束线”中辐照加速器的要求,在原有二极电子枪基础上增加了控制栅极。使用CST Particle Studio仿真研究了电子枪部分结构参数变化对引出束流强度的影响,设计出产生50 mA高品质束流的电子枪,并用PBGUNS(Particle Beam GUN Simulation)软件对设计结果进行验证。最后在电子枪实验平台上检验了电子枪结构参数变化对引出束流强度的影响规律,并对电子枪结构进行了优化。结果表明优化后的电子枪能够以阴极初级加热电压作粗调、栅极电压作细调的方式引出1μA～50 mA高品质电子束。     

NDZ-20医用电子直线加速器的注入系统

文章介绍了NDZ-20医用电子直线加速器的束流注入系统的结构和特性。电子枪为轰击型的皮尔斯电子枪。漂移管上的预聚焦线圈、偏掉线圈、导向线圈和束流前沿切割线圈用来实现对电子束的多种控制,实现加速器的ARC,ADC和BLC运用,以保证加速器运行的稳定性和可靠性,改善反馈加速器的能谱。     

高压冷阴极电子枪

电子感应加速器的技术指标中,γ射线强度是较重要的一个。提高强度可使物理实验结果更加准确,在探伤时可减少曝光时间。由俘获理输可知,提高强度的措施有:1.提高电子枪的注入电压;2.改善磁场的位阱形状;3.增加真空盒截面积;4.改进电子枪光学系统,减小束流散角;5.改进阴极,增加发射电流强度。本文只讨论为提高注入电压所采用的新型高压电源及改用冷阴极电子枪的问题。     

六硼化镧阴极在双等离子体离子源中的应用

一、引言早在50年代初,J.M.Lafferty就研究了六硼化镧阴极的电子发射特性。70年代中期以后,六硼化镧阴极广泛地应用于现代技术的许多领域。例如,等离子体发生器、强流离子源(包括用于聚变研究中的中性束注入源)、电子显微镜、质谱仪和一些电子器件(真空规管,热电离变换器等)。     

Characteristics of Plasma Spraying Torch with a Hollow Cathode

1. IntroductionPlasma spraying has became a welLestablishedand widely-used technology with various industrialapplications[1,2,3]. In traditional plasma sprating,the design of plasma torch has been essentially thesame, based on producing a plasma jet by a dc arcopersted between a stick-type cathode and a nozzleshaped anode[4,5]. The powder is injected radiallyillto the plasma flame either within the anode channel or a short distance from the anode. With radialinjection of powders the heating a…     

Oxide Coated Cathode Plasma Source of Linear Magnetized Plasma Device

Plasma source is the most important part of the laboratory plasma platform for fundamental plasma experimental research. Barium oxide coated cathode plasma source is well recognized as an effective technique due to its high electron emission current. An indirectly heated oxide coated cathode plasma source has been constructed on a linear magnetized plasma device. The electron emission current density can reach 2 A/cm 2 to 6 A/cm ² in pulsed mode within pulse length 5–20 ms. A 10 cm diameter, 2 m long plasma column with density 10 ¹⁸ m ⁻³ to 10 ¹⁹ m ³ and electron temperature T_e ≈ 3–7 eV is produced. The spatial uniformity of the emission ability is less than 4% and the discharge reproducibility is better than 97%. With a wide range of the plasma parameters, this kind of plasma source provides great flexibility for many basic plasma investigations. The detail of construction and initial characterization of oxide coated cathode are described in this paper.     

Effects of discharge parameters on the micro-hollow cathode sustained glow discharge

The effects of parameters such as pressure, first anode radius, and the cavity diameter on the micro-hollow cathode sustained glow discharge are investigated by using a two-dimensional self-consistent fluid model in pure argon. The results indicate that the three parameters influence the discharge in the regions inside and outside of the cavity. Under a fixed voltage on each electrode, a larger volume of high density plasma can be produced in the region between the first and the second anodes by selecting the appropriate pressure, the higher first anode, and the appropriate cavity diameter. As the pressure increases, the electron density inside the hollow cathode, the high density plasma volume between the first anode and second anodes, and the radial electric field in the cathode cavity initially increase and subsequently decrease. As the cavity diameter increases, the high-density plasma volume between the first and second anodes initially increases and subsequently decreases; whereas the electron density inside the hollow cathode decreases. As the first anode radius increases, the electron density increases both inside and outside of the cavity. Moreover, the increase of the electron density is more obvious in the microcathode sustained region than in the micro cavity region. The results reveal that the discharge inside the cavity interacts with that outside the cavity. The strong hollow cathode effect and the high-density plasma inside the cavity favor the formation of a sustained discharge between the first anode and the second anodes. Results also show that the radial boundary conditions exert a considerably weaker influence on the discharge except for a little change in the region close to the radial boundary.     

The dynamics of a nanosecond gas discharge development with an extended slot cathode in argon

The article presents the results of an experimental study and numerical modelling for the formation and development dynamics of a high-voltage transverse nanosecond discharge generated by a slot cathode in an argon medium at a pressure range of 1–10 Torr. Numerical modelling was carried out under similar experimental conditions for the processes of formation and propagation of ionisation waves, electron density distribution, excited atom and average electron energy in the discharge gap, including the cavity inside the cathode. At a pressure of p = 1 Torr, a classical version of a high-voltage discharge is demonstrated to take place with no penetration of the plasma into the cathode cavity and no observed hollow cathode effect. An increase in gas pressure to 5 Torr leads to a penetration of plasma into the cathode cavity with the formation of a cathodic potential drop (CPD) region. Electrons emitted from the side surfaces of the cavity pass through the CPD region without collisions, oscillate inside the cathode cavity; the hollow cathode effect is fully manifested. At р = 10 Torr, the modelling results qualitatively coincide with the results at р = 5 Torr; in this case, however, hardly any accelerated electrons are observed in the gap between the electrodes, due to their energetic relaxation both inside the cathode cavity and when exiting from it. In both cases, the plasma structure formed at the exit of the cathode cavity involves a concentration of charged particles an order of magnitude higher than that in the rest of the gap, leading to a self-limiting discharge current effect. The results of the numerical modelling are in good agreement with experimental data.     

托卡马克电场漂移电子注入的物理分析研究

对电场漂移电子注入中的电子束物理,电子注入情况下手 马克等离子的平衡,电子注入器中的物理问题等进行了分析研究。结果表明,漂移电子束的稳定条件是外加电场必须大于电子束本身所产生的电场;为了保持等离子体环的平衡,外加电压愈低愈好;     

间热式大面积六硼化镧中空阴极

介绍了适用于强流离子源的间热式大面积六硼化镧中空阴极。在１５ｃｍ双潘宁离子湖泊 上放电特性研究表明，该阴极性能良好，能可靠工作，使用过程中多次暴露于大气中，发射性能并未变坏，加热功率为１．４５ｋＷ，ＬａＢ６发射电流密度为２０Ａ／ｃｍ＾２，放电电流４００Ａ，脉冲宽度３０ｍｓ，放电波形重复性很好。使用１００ｈ后，发射体尺寸无明显变化。     

Three-dimensional non-equilibrium modeling of a DC multi-cathode arc plasma torch

In this paper, a three-dimensional non-equilibrium steady arc model is used to investigate the temperature, velocity and electromagnetic field in multi-cathode arc torch, and the formation mechanism of a large-area, uniform and diffused arc plasma is analyzed. The numerical simulation results show that a large volume plasma region can be formed in the central region of the generator during discharge. During this process, the maximum electron temperature appears near the cathode and in the central convergence region, while the maximum heavy particle temperature only appears in the central convergence region. This phenomenon is consistent with the experimental arc images. Near the cathode tip, the arc column is in a contraction state. In the area slightly away from the cathode, the six arc columns begin to join together. In the plasma generator, there is a large-scale current distribution in all directions of X, Y and Z, forming a stable arc plasma with a wide range of diffusion. The calculated electron temperature distribution is in good agreement with the measured electron temperature. The results suggest that the largearea diffused arc plasma in the multi-cathode arc torch is the combined effect of current distribution, convection heat transfer and heat conduction.     

Numerical simulation and experimental research on an inductively coupled RF plasma cathode

In this study, numerical simulation and discharge current tests were conducted on an inductively coupled radio frequency (RF) plasma cathode. Numerical simulations and experimental measurements were performed to study the factors influencing the electron extraction characteristics, including the gas type, gas flow, input power and extracting voltage. The simulation results were approximately consistent with the experimental results. We experimentally found that the RF input power mainly determines the extracted electron current. An electron current greater than 1 A was acquired at 270 W (RF input power), 2.766 sccm (xenon gas). Our results prove that an inductively coupled RF plasma cathode can be reasonable and feasible, particularly for low power electric propulsion devices.     

Plasma characteristics in the discharge region of a 20A emission current hollow cathode

Numerical calculation and fluid simulation methods were used to obtain the plasma characteristics in the discharge region of the LIPS-300 ion thruster’s 20 A emission current hollow cathode and to verify the structural design of the emitter.The results of the two methods indicated that the highest plasma density and electron temperature,which improved significantly in the orifice region,were located in the discharge region of the hollow cathode.The magnitude of plasma density was about 10~(21)m~(-3)in the emitter and orifice regions,as obtained by numerical calculations,but decreased exponentially in the plume region with the distance from the orifice exit.Meanwhile,compared to the emitter region,the electron temperature and current improved by about 36%in the orifice region.The hollow cathode performance test results were in good agreement with the numerical calculation results,which proved that that the structural design of the emitter and the orifice met the requirements of a 20 A emission current.The numerical calculation method can be used to estimate plasma characteristics in the preliminary design stage of hollow cathodes.