触发型真空弧放电特性研究

基于沿面放电设计了短间距的触发型真空弧放电装置,利用高速相机研究了触发真空弧放电特性,获得了不同放电时刻的放电图像。通过分析放电图像,发现主弧放电开始阶段,主弧电流主要为电子电流,而且在阳极附近观察到较强的离子电流。研究发现阴极斑的形成和等离子体的扩散是主间隙击穿的关键因素。初始阴极斑不仅为触发回路提供载流子,同时影响着主间隙的击穿。文章讨论了阴极表面离子鞘层对表面电场的影响,阴极表面场强可达107V/m。同时本文讨论了背景气压对电极间隙放电延迟时间的影响。     

多模式旋转磁场对电弧离子镀弧斑放电的影响分析

电弧离子镀工艺中,弧斑的放电形式、运动速率、运动方式的控制对于减少以至消除大颗粒的发射至关重要。本文采用自主研发的机械式旋转磁控弧源,围绕三种不同模式的旋转磁场下弧斑的放电行为及规律进行了研究,并从弧斑放电的物理机制出发,分析讨论了不同模式的旋转磁场对阴极斑点运动的影响机理。研究结果表明,多模式旋转磁场可以有效提高弧斑的运动速度、扩大放电面积、降低放电功率密度、减少大颗粒的发射,同时还能够大幅度提高靶材的利用率,拓展电弧离子镀的应用。     

应用于工具镀膜的磁场辅助离子镀弧源及其放电特性分析

针对几种应用于工具镀膜的磁场控制的电弧离子镀弧源,分析了其结构、工作原理以及弧斑运动、放电特性;比较了不同磁场辅助受控弧源的靶结构及磁场位形,并讨论了对弧斑运动、放电及镀膜工艺的影响;对磁场控制的电弧离子镀弧源的发展进行了展望。     

低气压阴极弧斑等离子体除去钢表面氧化层的实验研究

进行了低气压下直流阴极弧斑等离子体去除钢铁表面氧化层(除鳞)的实验研究,利用高速相机和示波器对放电过程进行了诊断。实验表明,阴极弧斑在样品表面快速随机运动。由于弧斑具有极高的电流密度,产生的局部高温使阴极弧斑下方的氧化层被瞬间蒸发、分解。除鳞后样品表面X射线衍射和扫描电镜分析表明,弧斑等离子体能有效地除去钢铁表面氧化层。放电电流是决定除鳞快慢的一个重要参数,单位时间除鳞的面积随放电电流的增大而增加,呈现线性关系,这与依据非静态爆裂ecton模型给出的分析结果相符合。     

新型阴极弧电源研制及脉冲增强电子发射(P3e)效应研究

本文研制了新型脉冲阴极弧电源,并实现了脉冲增强电子发射(P3e)以提高真空室内等离子体密度。该电源核心由脉冲发射和维持电流系统构成,由单片机和触摸屏系统协同控制和管理。对P3e电源进行放电特性和脉冲增强电子发射效应进行了研究。结果表明,在相同平均电弧电流条件下,与直流相比,P3e技术能够显著提高工件(基体)脉冲电流与平均电流。在电弧平均电流90 A时,基体脉冲电流由5 A提高到19.6 A,基体平均电流由2.2 A最大提高到4.6 A,表明脉冲增强了电子发射,进而获得高的等离子体密度,这将有助于增加膜层致密性、降低膜层应力。该新型电源对于阴极弧靶中毒抑制、膜层结构改善、膜层颗粒污染控制具有重要的意义。     

磁过滤阴极真空弧沉积装置研究中的等效电路方法

提出了模拟磁过滤阴极真空弧放电等离子体沉积装置阴极弧放电过程的等效电路，并用此电路定性研究了各参数对弧放电的影响，结果同实验符合的很好。     

多弧离子镀弧源靶工作条件对氮化钛薄膜中钛液滴的影响

本文研究了阴极靶弧电流大小、阴极靶表面热弧斑运动轨迹的电磁场控制、以及阴极靶脉冲弧沉积对多弧离子镀TiN薄膜中Ti液滴的影响。通过优化镀膜参数,可以有效地减少Ti液滴的数量和尺寸,提高TiN薄膜／工件基体之间的结合力。     

磁过滤阴极真空弧沉积装置研究中的等效电路方法

提出了模拟磁过滤阴极真空弧放电等离子体沉积装置阴极弧放电过程的等效电路 ,并用此电路定性研究了各参数对弧放电的影响 ,结果同实验符合的很好     

电磁场对电弧离子镀沉积AlTiN涂层的影响

主要研究电磁场对电弧离子镀沉积AlTiN涂层的影响。通过改变电磁场的电压,研究阴极弧斑在不同电磁场下的运动现象以及AlTiN涂层的微观结构和力学性能。结果表明阴极弧斑的运动受磁场电压的影响。增加磁场电压,弧斑更多的在电弧靶中心区域聚集。AlTiN涂层的大颗粒分布、沉积速率、微观结构和硬度相应地受电磁场电压的影响。文章对相关机理进行了研究。     

真空阴极弧离子镀阴极斑点的移动研究

建立了真空阴极弧离子镀圆形平面靶侧面引弧时,阴极斑点的受力模型,分析了影响电弧运动的因素,改进了圆形平面靶侧面形状,大大提高了石墨靶阴极斑点从侧面到靶平面的过渡速度。     

纳米Ag-Fe合金的真空电弧特性

利用微乳液法制备出纳米复合Ag-Fe合金,在真空条件下,利用高速摄影机观测Ag-Fe系列合金的阴极斑点运动,采用示波仪记录放电电流曲线,并利用扫描电子显微镜观察电极表面烧蚀状况.研究结果表明:Fe纳米粒子的加入使得电弧分散,电孤的寿命增加,截流值降低.     

真空阴极弧离子镀阴极斑点的移动研究

建立了真空阴极弧离子镀圆形平面靶侧面引弧时 ,阴极斑点的受力模型 ,分析了影响电弧运动的因素 ,改进了圆形平面靶侧面形状 ,大大提高了石墨靶阴极斑点从侧面到靶平面的过渡速度     

The effect of axisymmetric two-dimensional magnetic field on the configuration of vacuum-arc plasma

An experimental investigation is made of the effect of axisymmetric two-dimensional magnetic field on the forming of plasma and on the configuration of cathode spots in a vacuum-arc discharge. It is demonstrated that a magnetic field with a transverse (relative to the discharge axis) component has a significant effect on the shape of plasma column and on the rate of expansion of the cathode spot region. In a magnetic field, arc plasma has the form of truncated cone expanding toward the anode. The cathode spots take up a part of the cathode area which decreases with increasing magnetic field. Arguments are given in support of the assumption that the arrangement of cathode spots and the form of arc plasma are defined by the minimum principle similar to the Steinbeck principle. In so doing, the displacement of spots is caused by their emergence in a new region corresponding to a lower arc voltage. Also discussed is the mechanism associated with retrograde motion of cathode spot in view of the effect of azimuthal magnetic field on the axial component of current and of the effect of axial magnetic field on the azimuthal component of current.     

行波管用阴极表面黑斑现象的电子显微分析

针对行波管用阴极表面异常的黑斑现象,利用扫描电镜( SEM)和X射线能谱仪(EDS)对阴极的不同微区进行了对比分析,查找黑斑产生的原因,并对其对阴极发射性能造成的影响进行了探讨.结果表明,行波管内真空度下降,阴极中的发射物质与空气中的水汽和氧气反应,随着工作时间的延长,最终导致黑斑的出现.黑斑的出现严重影响阴极的发射性能,这对行波管的封装可靠性提出了较高的要求.     

Vacuum Arc Discharge on Integrally Cold Cathode

Initial researches of the existence of a cathode spot on the working surface were conducted in vacuum arc plasma sources of the coaxial design. The moving of the cathode spots on the limited sizes working surface does not give full picture of the development of the arc discharge. This article describes the vacuum arc plasma source of extended design generating the directed belt plasma stream and operating in pulse mode. The researches carried out give additional information about development of the cathode spots of the vacuum arc discharge. It is found that the speed of the cathode spots' motion depends on the cathode temperature.     

Influence of the tip effect of a carbon nanostructure on low current electrical arc initiation

During their setting off, circuit breakers and vacuum switch devices are accompanied by an electric arc whose physical and chemical properties are governed by emissive current sites at the cathode surface called cathode spots. Assuming the continuity of the current on the cathode surfaces, the cathode spots contribute to supply the electrical arc by electron emission and material ejection. Thus they cause erosion on the contact electrodes inducing a dysfunction of contactors. The apparition of these cathode spots is due essentially to dust particles and surface irregularities at different scales. This experimental work represents a contribution to the understanding of the electrical arc behaviour by an investigation at submicronic scale on the influences of nanostructured carbon tips on the electric arc initiation and the cathode spots birth.     

Dynamics studies of cathode spots in a vacuum-arc discharge with ring electrodes

The effect of an external pulse magnetic field with axial and radial components on electric characteristics of the discharge and the configuration of cathode spots of a vacuum arc discharge with ring electrodes is studied experimentally. For arc currents within the range of 0.05–2 kA, shots of the cathode spots at different instants of time are obtained. The dependences of the number of the spots on the discharge current and the mean current per spot are determined. It was found that the expansion rate of the cathode spots area depends significantly on the instant value of the discharge current. It is shown that, when the pulse magnetic field is applied, the discharge voltage increases and the discharge current and number of the cathode spots decreases. It was found that the current interruption is a probability process. The probabilities of the current interruption depending on the maximal value of the external pulse magnetic field induction are determined.     

Study of the direct current breakage process in an external nonuniform magnetic field

We study experimentally the influence of an external nonuniform magnetic field with transverse and longitudinal components on the electric characteristics, plasma configuration, and cathode spot arrangement of vaccum-arc discharge. It is revealed that for a cylindrical cathode, cathode spots are nonuniformly distributed on the cathode surface, the spot configuration has no axial symmetry, and the arrangement of spots changes in time depending on the induction value of the external pulsed magnetic field. With an increase in induction, spots (on average) are arranged closer to the cathode, i.e., displaced to the region of weaker transverse field. For two cathode geometries, the probabilities of direct current breakage depending on the induction of the external nonuniform magnetic field are experimentally determined. To determine the conditions of current breakage, a three-dimensional mathematical model of ion motion is suggested and the current breakage criterion is formulated. The trajectories of fast cathode ions in an electrode system with a ring cathode have been calculated using the model. Calculations were performed in a nonuniform magnetic field, the radial and axial components of which have been measured experimentally. It is shown that conditions of current breakage determined with this criterion agree with the results of experiment.     

后栅极场发射显示板结构参数在公差范围内变化对工作特性的影响

后栅极场发射显示板是一种常用的场致发射器件。该器件结构由阳极、阴极和栅极组成,并且栅极置于阴极背面。本文采用模拟计算的方法研究了标准结构场发射区域内的电场分布、阴极表面的发射情况、电子轨迹和着屏束斑。并研究了关键结构参数在公差范围内变化对阴极发射特性和阳极着屏束斑的影响。计算结果显示结构参数在公差范围内的变化对阴极发射状况,阳极束斑栅极调制特性的影响很小,进而证明了后栅极结构对工艺一致性要求较低。     

金属楔形发射体电子场发射理论研究

提出楔形发射体的电子场发射理论并给出计算实例。该理论以单原子发射点假设为基础，用经典电动力学方法计算出楔形发射体的隧道势垒，然后用Numerov方法计算其透射比，最后得到楔形发射体的场发射伏安特性，还分析了几何结构参数对楔形发射体场发射特性的影响。