Uniqueness Theorem for the Non-Local Ionization Source in Glow Discharge and Hollow Cathode

The paper is devoted to the proof of the uniqueness theorem for solution of the equation for the non-local ionization source in a glow discharge and a hollow cathode in general 3D geometry. The theorem is applied to wide class of electric field configurations, and to the walls of discharge volume, which have a property of incomplete absorption of the electrons. Cathode is regarded as interior singular source, which is placed arbitrarily close to the wall. The existence of solution is considered also. During the proof of the theorem many of useful structure formulae are obtained. Elements of the proof structure, which have arisen, are found to have physical sense. It makes clear physical construction of non-local electron avalanche, which builds a source of ionization in glow discharge at low pressures. Last has decisive significance to understand the hollow cathode discharge configuration and the hollow cathode effect.

Experimental investigations of enhanced glow based on a pulsed hollow-cathode discharge

In this work, the pulsed hollow cathode discharges at low pressure argon with an axial magnetic field were studied. The results indicate that the pulsed discharge is operated in an enhanced glow(EG) mode. Under the same conditions, the discharge current of the pulsed discharge is two or three orders higher than that of the direct current discharge. The spatial and temporal evolution of the light emission shows that, the current fluctuation at the rising edge of the pulse plays an important role for the EG discharge of pulsed hollow cathode, which forms a high-density, highcurrent and long-distance plasma column outside the cavity.

Best Magnetic Condition to Generate Hollow Cathode Glow Plasma in High Vacuum

Based on magnetron hollow cathode discharge, the magnetic condition of glow plasma generation in high vacuum, including both direction and magnitude of the applied mag- netic field, is theoretically derived and experimentally evaluated in this paper. Single particle orbital theory is introduced to discuss the possibilities to generate glow plasma at gas pressure under 10-2 Pa when the magnetic field direction is parallel or perpendicular or oblique to the electric field direction. A quantitative estimation criterion of magnetic induction intensity is also proposed in theory. The comparison with experiments suggests that glow plasma in high vacuum will form more easily in oblique magnetic field condition and that the criterion is accurate enough to estimate magnetic induction intensity at a certain gas pressure.

Direct determination of trace amounts of acetic acid using a novel ambient glow discharge ion source

A novel ambient glow discharge ion source with improved line-cylinder electrodes is put forward and designed in this paper. The diameters of inner and outer electrodes are 0.16 and 4 mm respectively. With a special assembly method, a perfect coaxiality of the two electrodes is obtained. From the gas discharge experiment, it can be seen that the discharge can stably work in normal glow discharge mode. The operating currents of the ion source are in an order of milliamperes and can generate a much larger number and wider variety of reagent ions. The MS experiment shows that the ion source has higher detection sensitivity,

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.

Glowing discharge ion source of ion mobility spectrometry

The paper investigated a new method of analyzing perfume odors.The study adopted IMS with glow dischargeas ion source and with positive ion mode.We got the quality characteristics of perfume odors in this way without any collection and concentration process.The quality of perfume odors can be identified by IMS peak characteristics,and the characteristics of different quality of perfume also can be identified.In summary,the IMS is an effective technique in the perfume odor detection,it is also a new way of gas sample analysis.

Measurements of plasma parameters in a hollow electrode AC glow discharge in helium

Measurements of the plasma parameters of coaxial gridded hollow electrode alternating current(AC)discharge helium plasma were carried out using an improved probe diagnostic technology.The measurements were performed under well-defined discharge conditions(chamber geometry,input power,AC power frequency,and external electrical characteristics).The problems encountered in describing the characteristics of AC discharge in many probe diagnostic methods were addressed by using an improved probe diagnostics design.This design can also be applied to the measurement of plasma parameters in many kinds of plasma sources in which the probe potential fluctuates with the discharge current.Several parameters of the hollow electrode AC helium discharge plasma were measured,including the plasma density,electron temperature,plasma density profiles,and changes in plasma density at different input power values and helium pressures.The characteristics of the coaxial gridded hollow electrode plasma determined by the experiments are suitable for comparison with plasma simulations,and for use in many applications of hollow cathode plasma.

High Pressure Micro-Slot Hollow Cathode Discharge

A direct current glow discharge source structure operating at high pressure based on the micro-slot hollow cathode is presented in this article. A 100 μm width slot cathode was fabricated of copper, and a stable DC glow discharge with an area of 0.5 mm^2 was produced in noble gases （He, Ne） and air over a wide pressure range （kPa - 10 kPa）. The current-voltage characteristics and the near UV radiation emission of the discharge were studied.

Cylindrical Micro-hollow Cathode Discharge at Atmospheric Pressure

The mechanism of micro-hollow cathode discharge at atmospheric pressure is investigated through simulations using two-dimensional fluid model combined with a transport model for metastable atoms.In the simulations,electric potential,electric field,particle density,and mean electron energy of the discharge are calculated.The results show that the two characteristic regions of the discharge,i.e.cathode drop and negative glow can be distinguished in the simulation.The cathode drop is characterized by strong electric field and high mean electron energy,while quasi-neutral plasma of high density and exists in the negative glow.The peak value of electron density can reach the order of 1017cm-3.The electron temperature varies from several eV to tens of eV.The influence of cathode dimension on the discharge characteristics is also investigated.

Ceramic alloying with Ti-N deposition and diffusion of multi-layers by plasma surface alloying technique

High quality TiN multi-layer was obtained on steel substrate by combined technology of plasma glow discharge sputtering, hollow cathode effect and interfacial diffusion. The TiN multi-layer consists of deposition layer and diffusion layer. Its morphology, structure and chemical compositions were analyzed. The microhardness and wear resistance were measured. The results indicate that the diffusion of Ti and N into the substrate leads to a strong interfacial adhesion. The thickness of TiN multi-layer is about 10μm. The strongest diffraction is on the (200) crystal plane of TiN. The surface hardness is about to 2300(HV_ 0.1). The wear resistance of the TiN ceramic alloying multi-layer is excellent and the friction coefficient is low under dry sliding conditions.

磁场辅助的小型化潘宁离子源点时燃放电特性研究

潘宁离子源在小型化过程中会遇到点燃电压升高及阴极与阳极间绝缘材料击穿和不稳定放电等问题。为促使潘宁离子源内部结构小型化,文中在恒定电场下,通过增加磁场的方式实现潘宁离子源稳定放电,达到降电压放电,并延长了绝缘材料使用寿命,实现了稳定放电。此外,采用COMSOL Multiphysics软件对改进后的离子源内部电场、磁场的分布进行仿真,模拟分析电子在不同区域的运动和电离情况,据此建立了基于恒定电场增加磁场的点燃物理模型。该模型与实际的点燃实验进行对比的结果表明,改进后的小型潘宁离子源在电压恒定为0.8 kV时,仅将磁场增强至156.29 mT即可实现小型潘宁离子源稳定放电。

空心阴极耦合放电的寿命损耗机理研究综述

空心阴极和离子推力器或霍尔推力器的耦合放电与其和平板阳极的独立放电有明显差异,主要表现为工作特性不同和寿命大幅缩短等。基于空心阴极的设计寿命与其在推力器中实际寿命显著不同的事实,归纳分析了空心阴极在推力器中寿命缩短的主要原因,总结了推力器中电场、磁场、背景中性气体密度等因素对空心阴极寿命的影响机理研究现状,并提出需要进一步深化的主要研究内容。

双层辉光离子渗金属技术特点分析

详细介绍了双层辉光离子渗金属技术的基本原理、放电模式及渗金属过程。并就该技术的优势和特点进行了理论分析。结果表明,该技术在表面合金化技术领域中,是适合于高熔点金属表面合金化和采用高熔点金属对铁基或某些熔点较高的有色金属表面进行合金化的实用工艺。

加弧辉光放电等离子表面合金化

介绍了加弧辉光离子渗金属装置及基本原理在辉光离子渗金属装置中,引入冷阴极电弧源,实现了快速渗金属,已成功地在普通碳钢表面渗入Ti,Al及Cr—Ni等合金元素,同时分析了10钢渗Ti处理后的渗层组织特征、成分分布。

双层辉光离子渗金属技术特点

分析了双层辉光技术的特点,指出该技术在材料表面合金化方面,是一项适合于高熔点金属表面合金化和采用高熔点金属对铁基或某些熔点较高的有色金属材料进行表面合金化的工艺技术。

氮气空心阴极辉光放电等离子体离子的蒙特卡罗模拟研究

采用蒙特卡罗模型对氮空心阴极放电等离子体鞘层离子(N2+、N+)的输运过程进行了模拟研究,计算了阴极鞘层中氮离子(N2+、N+)的能量及角分布的空间变化和粒子密度及平均能量随放电参数的变化规律。研究结果表明:空心阴极放电产生的氮离子,在鞘层输运过程中,N2+是密度几乎不变的低能粒子;N+是密度逐渐减少的高能粒子。随着电压增加,N+密度减小,平均能量增加;N2+密度和平均能量变化不明显。能量及入射角的相对分布规律与平板电极氮直流辉光放电基本类似,但圆筒空心阴极放电更有利于氮离子的产生。

等离子体辉光溅射反应复合渗镀合成TiN的研究

本文介绍了一种新的制备TiN的工艺方法。利用辉光放电溅射现象、尖端放电和空心阴极效应,在钢铁材料表面直接复合形成TiN渗镀扩散层。用X射线衍射、辉光放电剥层成分分析仪、显微硬度仪等方法,对复合层进行分析。结果表明:本研究方法复合形成的TiN渗镀层,TiN呈溶质固溶于基体表面层中,呈梯度沿基体向内分布。该表面复合层与一般表面沉积的TiN层不同,是冶金结合扩散层,不会产生剥落现象。在1020℃复合形成渗镀层时,层深可达15μm左右,并得到择优取向为(200)晶面的TiN相,渗镀TiN层的表面硬度随渗镀温度的提高而增加,渗镀TiN层随渗镀温度的升高而增厚。

大气压直流辉光放电装置的实验与分析

为了能减小放电装置的体积,以应用于便携式仪器,设计了线-筒型大气压直流辉光放电装置,放电间隙仅1.92mm。它主要由内线电极、外筒电极组成,线电极直径为0.16mm,筒电极直径为4mm。观察并说明了从电晕放电向辉光放电过渡的过程。通过放电波形和图像验证了其处于辉光放电状态。推导了利用氮气第二正带系计算振动温度和转动温度的算法,并利用光谱仪(Acton Spectrapro 2500i)采集所产生的等离子体的发射光谱,计算得到该等离子体的振动温度在2 360K左右,转动温度在830K左右。将该装置作为离子源应用于敞开式质谱中,实验结果表明,该直流大气压辉光放电形成的等离子体可以很好地离子化甲酸、乙酸、苯酚等物质。

大气压下辉光放电的产生

阐述了产生大气压下辉光放电的几种方法。在直流电场中,通过改变阴极的结构,抑制了辉光放电向弧光放电的过渡,从而实现大气压下辉光放电;在交流电场中,利用介质阻挡层和高频激励源,可获得稳定均匀的大气压下辉光放电。

辉光放电质谱仪的历史现状与未来

本文介绍辉光放电（ＧｌｏｗＤｉｓｃｈａｒｇｅ，ＧＤ）作为质谱仪离子源的发展过程，叙述了多种形式的辉光放电离子源的特性及应用，并就辉光放电质谱仪做为分析手段与其他分析方法进行了比较，对该领域的杰出人士及辉光放电商品仪器进行了介绍，最后根据专家们的分析，探讨了辉光放电质谱仪的未来工作方向。