空心阴极真空电弧基本特性的研究

研究了空心阴极真空电弧焊接(HCVAW)的一些基本现象和特性.研究表明,HCVAW电弧有两种基本电弧形态发散型和积聚型;采用铜阳极时,HCVAW电弧光谱主要是受激氩原子谱线和一次氩离子谱线组成.并讨论了氩气流量、弧长和空心阴极内径对电弧伏安特性的影响.     

焊接电弧光谱的分布特征

在试验的基础上,给出了焊接电弧光谱的频域及空间分布的测试结果,分析了焊接电弧光谱的结构。通过分析得出了ＴＩＧ焊电弧光谱空间分布的差异性和ＭＩＧ焊电弧光谱空间分布的相似性,着重指出ＭＩＧ焊电弧光谱与熔滴过渡之间存在密切关系。此外,还对焊接电弧光谱特征的应用提出了方向。     

空心钨极中心负压电弧基础特性研究

为了提高传统钨极惰性气体保护(Tungsten inert gas,TIG)焊电弧的能量密度和热源边界的能量梯度,保证焊接热输入均衡,规避输入能量分散,提出空心钨极中心负压电弧焊接方法,设计并构建空心钨极中心负压电弧焊接系统,介绍系统的组成及操作方法。利用高速摄像机拍摄空心钨极中心负压电弧的宏观形态,进行定点焊接烧蚀试验,并对阳极表面熔池尺寸和焊接接头的宏观形貌进行分析。试验结果表明,在电弧自身刚性的作用下,空心钨极中心负压电弧能够稳定地建立于空心钨极和阳极工件之间;与传统TIG焊电弧相比,在宏观形态上,空心钨极中心负压电弧的弧柱沿径向收缩,呈现拘束状,空心钨极的尖端呈现白炽状态;在焊接接头的宏观形貌上,空心钨极中心负压电弧对应焊接接头的熔深大,熔宽小,焊缝成形好。     

光谱法水下焊接电弧温度的研究

利用等离子体光谱诊断法对水下焊接电弧温度进行了比较系统的研究，对水下湿法焊接与干法焊接的电弧温度进行了对比分析，讨论了水的冷却作用及水压力对水下电弧温度的影响。探讨了焊接规范、焊条药皮中铁粉和铝热剂的质量分数等因素对水下焊接电弧温度的影响，获得的研究成果对水下焊接电弧物理及焊接冶金的研究有参考价值     

真空电弧阴极斑点的研究方法

通过论述了真空状态下电击穿的一般原理,介绍了真空电弧的阴极斑点的研究方法和研究内客.分析了抗电弧烧蚀能力强的阴极材料和其它粗晶、纳晶金属和合金的电极材料的主要区别.同时也指出了现有研究方法的局限性.     

高速旋转电弧窄间隙MAG焊接技术

针对现代制造业中大厚板焊接的技术现状,该研究提出一种高速旋转电弧窄间隙MAG焊接新工艺。该工艺以空心轴电机直接驱动导电杆高速旋转,带动从偏心导电嘴中送出的焊丝端部的电弧在坡口内高速旋转,以达到改善坡口两侧壁熔透的目的。这种以空心轴电机驱动的旋转电弧窄间隙焊接方法及装置,设计方案新颖,创新性强,焊炬结构简单紧凑,电弧旋转速度和旋转直径调节方便,实用性好,适用于平位置的大厚板窄间隙熔化极气体保护焊接。     

熔滴过渡光谱传感与控制的研究

焊接电弧光谱是一个丰富的信息源,电弧的各种物理过程都能在电弧光谱中体现,利用电弧光谱信息能很好地检测和控制脉冲焊熔滴过渡。对电弧光谱辐射情况和对光辐射和接收系统进行了深入的研究和分析,抛弃了一般特征光谱检测设备所必需采用的光谱仪和复杂的光路系统,选用干涉滤光片,选择光谱窗口,设计并制作小型光谱传感器。对喷射过渡过程进行了熔滴过渡检测,利用光谱信息实现了脉冲焊熔滴过渡精确控制为焊接过程精确控制提供了一种新的方法和手段。     

基于电弧光谱的钢熔化极惰性气体保护焊质量判识

通过对熔化极惰性气体保护电弧焊(MIG焊)电弧光谱分布进行采集,研究其光谱分布的基本特征,并基于光谱分布的分析,通过预设干扰因素,对不同特征谱段光谱信号随焊接过程的变化进行采集,寻求MIG焊接质量在线光谱测控的理论依据和工程实现.研究结果表明,MIG焊电弧光谱在不同谱段存在金属谱线和Ar谱线聚集区.在不同弧长下的不同熔滴过渡形态,其光谱信号在特征谱段得到明显反映,电流变化引起的焊道变宽也有很好的特征信号;不同干扰因素引起的焊接缺陷,在焊接电弧光谱信号不同谱段的分布和变化规律不同,通过对特征谱段信息的采集,可以获得关于焊接过程信息的特征信号,从而实现对MIG焊接质量的分类判识.     

电弧光谱信息及其在焊接过程测控上的应用

本文从焊接电弧光谱信息内容及其应用实例两个方面揭示了光谱信息与弧焊过程物理现象之间的本质联系,同时说明光谱诊断法在弧焊过程测控中的意义和应用潜力。对焊接电弧光谱信息的开发利用提供了一些有益的经验。     

气幕式旋转电弧传感器结构设计

针对水下焊接焊缝质量差等问题,设计了一种用于水下局部干法焊接的气幕式旋转电弧传感器来改善水下焊接质量。传感器采用空心电机驱动,通过偏心机构可进行圆锥摆动;传感器的排水罩采用了收缩喷管的结构,有利于在喷嘴附近获得高速均匀的气流;加工出了气幕式旋转电弧传感器实物,经过上电测试表明运转情况良好且能有效采集到信号。     

An arc generator of a broad plasma stream

The design and basic parameters of an arc plasma generator based on a combined cathode are described. The cathode consists of a hot tungsten filament located in the hollow cathode. A plasma stream with a cross section of 150×10 cm² and a density of ∼10¹⁰ cm⁻³ at a pressure of 0.1–1 Pa is generated at a discharge current of up to 60 A without a cathode spot. The plasma generator can be utilized for final cleaning and activation of surfaces of materials and articles before depositing functional coatings on them and in plasma-assisted deposition by using either vacuum arc or magnetron discharges.     

Generation of Gas Discharge Plasma by an Arc Source with a Cold Hollow Cathode

The results from a study of an arc plasma source with a cold hollow cathode are presented. The source generates plasma with a density of ∼10¹⁰ cm⁻³ in a volume of ∼0.2 m³ at discharge currents of up to 150 A, an arc discharge operating voltage of 30–40 V, and a low pressure of 0.1–1 Pa. The motion of the cathode spot in the crossed electric and magnetic fields inside the hollow cathode and the cathode’s special design make it possible to eliminate almost completely the penetration of the sputtered cathode material into the working vacuum chamber.__________Translated from Pribory i Tekhnika Eksperimenta, No. 3, 2005, pp. 62–66.Original Russian Text Copyright © 2005 by Schanin, Koval, Akhmadeev.     

Broad beam sources of fast molecules with segmented cold cathodes and emissive grids

Experimental study of fast neutral atom and molecule beam sources with rectangular and circular cross-section of the beam up to 0.8 m² is carried out and the study results are presented. The fast particles are produced as a result of charge exchange collisions between gas molecules and ions accelerated by potential drop between the plasma emitter of the beam source and the secondary plasma inside the processing vacuum chamber. As the emitter is used a glow discharge plasma, whose electrons are confined in an electrostatic trap formed by a cold hollow cathode and an emissive grid, which is negative both to the cathode and to the chamber. In order to prevent from breakdowns between the emitter and the cathode at a current in the cathode circuit up to 10 A as well as between the emitter and the grid at a voltage between them up to 10 kV the cathode and the grid are composed of isolated from each other segments, which are connected to power supplies through resistors. When resistance of the resistorR > U/I ₀, where U is the power supply voltage and I ₀ is the minimal current of stable vacuum arc for a given segment material, then transition from the glow discharge to the steady-state vacuum arc is totally excluded in spite of numerous breakdowns of microsecond duration due to contamination of the source electrodes during its operation with dielectric films and other stimulants of the arc.     

Characteristic of a triple-cathode vacuum arc plasma source

In order to generate a better ion beam, a triple-cathode vacuum arc plasma source has been developed. Three plasma generators in the vacuum arc plasma source are equally located on a circle. Each generator initiated by means of a high-voltage breakdown between the cathode and the anode could be operated separately or simultaneously. The arc plasma expands from the cathode spot region in vacuum. In order to study the behaviors of expanding plasma plume generated in the vacuum arc plasma source, a Langmuir probe array is employed to measure the saturated ion current of the vacuum arc plasma source. The time-dependence profiles of the saturated current density of the triple vacuum arc plasma source operated separately and simultaneously are given. Furthermore, the plasma characteristic of this vacuum arc plasma source is also presented in the paper.     

Influence of discharge gap on the discharge stability in a short vacuum arc ion source

The influence of the discharge gap between cathode and anode on the discharge stability in a short vacuum arc (SVA) ion source is presented in this paper. Planar cathode and cylindrical hollow anode made of titanium are investigated. There is a great need in present accelerator injection research for SVA source to produce the small deviation of the ion current beam. Current research shows that increasing the short discharge gap can reduce the level of ion current deviation and ion charge deviation from 29% and 31% to 15% and 17%, respectively. A microplasma plume generation mechanism in SVA and scanning electron microscopic results can be used to explain this interesting phenomenon.     

A Plasma Stopper in a Hollow Cathode

A cap with a hole was mounted on the top of a cylindrical hollow cathode. The hole diameter ranged from 10 to 90% of the inner diameter of the hollow cathode. As a result, a plasma stopper was formed in the cathode cavity near the hole. The stopper hindered the plasma-forming gas flow from the cathode cavity into the vacuum chamber. This caused a pressure difference between the cathode cavity and the vacuum chamber. It was found that the pressure difference depended on the diameter of the hole in the cap. A cap with a hole of 4 mm in diameter mounted on the top of a hollow cathode with an inner diameter of 20 mm allowed a pressure difference of three orders of magnitude to be attained.     

交流脉冲式磁控溅射靶极电源的研制

本文介绍了一种中频交流脉冲式磁控溅射靶极电源。该电源采用全桥逆变拓扑电路、PWM控制方式、输出功率叠加的方案，具有快速的过流检测与保护功能。在等离子体负载下进行了抑制弧光放电和空心阴极效应的实验，同低频直流脉冲电源相比，交流脉冲放电对其抑制是非常有效的。这表明该电源作为磁控溅射靶极电源是完全可行的，也为进一步探索交流磁控溅射新工艺提供了可靠的研究设备。     

Gas discharge source of metal vapor and fast gas atoms

A source of metal atom flow coinciding in time and space with a flow of fast gas atoms has been studied and the study results are presented. The fast particles are produced due to charge exchange collisions of ions accelerated by potential difference between a plasma emitter inside the source and secondary plasma inside a process vacuum chamber. The emitter is the glow discharge plasma, whose electrons are confined in an electrostatic trap formed by a cold hollow cathode and an emissive grid the latter being negative both to the cathode and the chamber. The metal atoms are produced due to sputtering a target placed at the hollow cathode bottom by ions from the plasma emitter with energy up to 3 keV. Sputtered atoms cross the emitter, together with accelerated ions enter the chamber through the emissive grid and deposit on pieces placed therein. When a mixture of argon and nitrogen is used, the metal nitride coatings are being synthesized and interruptedly bombarded during the synthesis by atoms and molecules with energy variable from ～10 to ～300 eV.     

Angular distribution of plasma in the vacuum arc ion source

This paper presents measurements of the angular distribution of the plasma components and different charge states of metal ions generated by a MEVVA-type ion source and measured by a time-of-flight mass-spectrometer. The experiments were performed for different cathode materials (Al, Cu, and Ti) and for different parameters of the vacuum arc discharge. The results are compared with prior results reported by other authors. The influence of different discharge parameters on the angular distribution in a vacuum arc source is discussed.