Hydrodynamic Limit for an Arc Discharge at Atmospheric Pressure

In this paper we study a partially ionized plasma that corresponds to an arc discharge at atmospheric pressure. We derive an inviscid hydrodynamic/diffusion limit, characterized by two temperatures, from a system of Boltzmann type transport equations modelling that plasma problem. The original property of this system is that impact ionization is a leading order collisional process. As a consequence, the density of electrons is given in terms of the density of the other species (and its temperature) via a Saha law.     

Plasma of Electric Arc Discharge between Melted Electrodes

Plasma of electric arc discharge between melted electrodes was experimentally investigated. Diagnostics of electric arc plasma was carried out. Optical emission and absorption spectroscopy was used to obtain radial profiles of temperature, electron density and neutral atoms concentration. The influence of electrode condition on plasma parameters was evaluated. It was found that the copper vapour in plasma tends to be located at the arc axis.     

Obtaining Titanium Carbide in an Atmospheric Electric Discharge Plasma

Technical Physics - The results of experimental studies on the development of scientific and technical foundations of a method to obtain cubic titanium carbide in plasma of a DC arc discharge...     

常压介质阻挡放电氧气大气谱带分析

观测了氧气常压介质阻挡放电过程产生的发射光谱,利用氧气大气谱带(b 1Σ＋_g→X 3Σ-_g)转动结构的拟合光谱与实验光谱的比较和氧原子发射谱线测量了等离子体的气体温度和电子温度; 通过分析氧气常见激发态(a 1Δ_g,b 1Σ＋_g和A 3Σ＋_g)的产生和猝灭途径,结合氧气激发、解离过程的动力学数据,探讨了在大气压介质阻挡放电条件下氧气大气谱带的产生原因。结果表明：在该实验条件下氧气常压介质阻挡放电时电子温度(11 800±400) K远高于气体温度(650±20) K,由于a 1Δ_g的辐射跃迁概率太小,且A 3Σ＋_g在高气压下很容易被猝灭,实验中没有观测到这两个激发态的辐射,而测到了具有清晰转动结构的氧气大气谱带。     

Modelling of a Spherical Electric Discharge at Atmospheric Pressure Under Higher Modes of Incident Microwaves

We present a spherical microwave discharge model, which takes into account the higher modes of the incident electromagnetic waves. The discharge model is constructed on the basis of the channel approximation of the LTE plasma. Numerical experiments are carried out for the discharge in an argon at atmospheric pressure. Results are presented for the characteristics of the discharge plasma against the external parameters (the size of the discharge chamber and the applied electromagnetic field mode, power and frequency). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

吸收光谱法测量大气压空气介质阻挡放电的臭氧浓度

臭氧作为一种强氧化剂和杀菌剂,在污染物降解,食品加工,杀菌消毒,医疗卫生等方面有着非常广泛的应用。大气压介质阻挡放电是一种极为高效的产生臭氧的方法,利用平行平板介质阻挡放电装置,采用交流高压激励,产生了大气压空气非平衡态等离子体。通过测量其电压和发光信号,发现在电压的正、负半周期均存在着许多随机的放电脉冲,并且其脉宽均在几十到几百纳秒之间,这表明其机制是流光放电。放电的光学发射谱包含氮分子的第二正带系(C 3Π-B 3Π)和第一正带系(B 3П-A 3П),氮分子离子的第一负带系(B 2Σ-X 2Σ),以及氧原子谱线(715.7和799.5 nm)。由于流光放电在紫外区域(200~300 nm)没有明显的发射谱线,但臭氧在此区域存在吸收峰,因此可以利用此区域的紫外吸收光谱测量放电产生的臭氧浓度。吸收光谱法可以有效的监测其臭氧浓度的变化情况,其优势在于操作简单,对实验环境要求低,可在放电条件下使用,并且可以连续监测臭氧浓度变化。基于此,通过Beer-Lambert定律计算了臭氧浓度随实验参数的变化,结果发现随外加电压幅值和驱动频率的增加,臭氧浓度升高。这些结果对于大气压介质阻挡放电的工业应用具有重要价值。     

大气压介质阻挡辉光放电中放电电流的测量与分析

介质阻挡放电产生的低温等离子体具有广泛的应用前景而成为研究热点。文章利用平行平板介质阻挡放电装置,在流动的氦气中实现了大气压均匀辉光放电,得到了大气压下的均匀等离子体。利用电学方法将放电电流从总电流中分离出来,从而得到了辉光放电的放电电流。通过分析放电电流、外加电压、气隙上电压以及壁电荷电量之间的相互关系,可以研究气体放电过程中壁电荷积累的微观动力学行为。实验结果表明壁电荷主要是在放电电流脉冲持续期间积累的,但电流脉冲结束后,由于气隙电压没有改变极性,壁电荷还会逐渐积累,气隙电压改变极性后,壁电荷量随时间减小。这些结果对壁电荷在介质阻挡辉光放电中作用的深入研究和大气压介质阻挡辉光放电的工业应用具有重要意义。     

Concentric-Ring Patterns in a Helium Dielectric Barrier Discharge at Atmospheric Pressure

We perform the theoretical simulation of the concentric-ring patterns between two parallel electrodes covered with thin dielectric layers within the scope of a two-dimensional diffusion-drift model at atmospheric pressure. The time evolution of the discharge patterns is studied and the concentric-ring patterns with different radii shift alternately. The spatial-temporal evolution of electron density in a cycle at different time scales is performed.     

Numerical Investigation of a Surface Barrier Discharge in Air at Atmospheric Pressure

Russian Physics Journal - An extended hydrodynamic model describing the surface dielectric discharge in air is formulated in the paper. Preliminary numerical calculations have been performed...     

大气压氩气放电六边形斑图的电子激发温度研究

采用特殊设计的气体介质阻挡放电实验装置,对大气压氩气放电六边形斑图的放电信号及激发光谱进行了测量。采用发射光谱强度比法,计算了放电丝呈六边形斑图时的电子激发温度。实验发现,随着驱动电压频率的升高,六边形斑图的电子激发温度明显升高,各放电通道之间的放电时间相关程度提高。该工作对控制斑图的形成和研究斑图动力学具有重要参考价值。     

直流大气压电晕放电电子密度的光谱研究

利用自制针—板式放电装置,在大气中进行电晕放电实验。用发光区域照片光斑的大小,讨论了电晕层厚度与电源电压的关系。在相同针板间距下,电晕层厚度随着电压的升高而增大;在相同电压下,电晕层厚度随着针板间距的增大而减小。由于高能电子密度能够通过氮分子第二正带系337.1 nm的光谱强度大小反映,因此对氮分子第二正带系337.1 nm谱线的强度用发射光谱法进行了测量。实验结果发现在针尖附近高能电子密度最大,并且高能电子密度随电压的升高而增大;电压一定时,高能电子密度随针板间距的增大而减小。在针板间距和电源电压不变的情况下,高能电子密度随针尖曲率半径的减小而增大。     

大气压氩气介质阻挡放电中的电子激发温度

采用发射光谱强度比法,测量了大气压氩气介质阻挡放电(DBD)中的电子激发温度。实验在690～800 nm的范围内测量了大气压氩气DBD的发射光谱,经分析发现这些谱线全部是氩原子的发射谱线。为了测量电子激发温度,选用相距较近的763.51 nm(2P₆→1S₅),772.42 nm(2P₂→1S₃)的两条光谱线。结果发现电子温度的范围为0.1～0.5 eV,电子激发温度随电压的增加而增加,随流量的增加而减小。实验还发现氩气流动与非流动时电子激发温度有明显的差别。上述结果对介质阻挡放电在工业领域上的应用具有重要意义。     

Atmospheric Pressure DC Glow Discharge in Semiconductor Gas Discharge Electronic Devices

The stabilization of dc glow discharges in a dc plasma is studied experimentally in air and neon media functions of pressure $p$, interelectrode distances $d$, and diameter $D$ of the cathode areas in the semiconductor gas discharge electronic devices (SGDED) with GaAs cathode. Comparision of current and discharge light emission (DLE) from SGDED are used for the determination of the stabilization under low- and atmospheric-pressure glow microdischarge conditions. It is found that uniform DLE can be generated in Ne up to atmosphere pressure different from the case in air under specific conditions. Apart from the homegeneous results, nonhomogeneous current–voltage characteristic forms are also observed for some parameter sets. The experimental results reveal different discharge behaviors in both gas media at atmospheric pressure.      

氩气介质阻挡放电的发光特性

本文使用水电极介质阻挡放电装置,采用光学方法测量了氩气介质阻挡放电的发光特性。发现在驱动电压处于一定的范围内时,放电处于丝极模式,在驱动电压的每半周期内,无论是放电的总光还是单个微通道的放电发光均只有一次脉冲,单个微放电的时间为2μs,而总放电时间为2.4μs,这表明在氩气的丝极模式中,各单丝产生与熄灭的时间极其接近,各个放电丝之间有着很好的时间相关性。最后将本文的结果与空气中介质阻挡放电丝极模式的发光特性相比较,空气放电在每半周内的总光信号由多个脉冲组成,而每一个脉冲对应多个放电丝,因而氩气中各个放电微通道之间的时间相关性远强于空气的情况。     

大气压下石英毛细管内氩等离子体放电的发射光谱诊断

在长度为20 cm的石英毛细管内利用两个边缘锋利的中空的针型电极之间的氩气放电产生了高电子密度的大气压等离子体。利用发射光谱对所获得的等离子体的几个重要参数进行了诊断。利用计算机谱线拟合法合成了300 nm附近OH(A-X)的(0-0)转动谱带并通过与测量谱线的比较确定了等离子体的气体温度,根据H_β谱线Stark展宽法计算了等离子体的电子密度,采用玻尔兹曼曲线斜率法依据测得的有关氩的发射光谱估算了等离子体的电子温度。研究结果表明,这种石英毛细管内弧光放电等离子体的气体温度约为(1 100±50)K;电子密度数量级在1014 cm-3;电子温度约为(14 515±500)K。     

Electric Field Mechanism of Thin Plasma Jet Formation in an Open Atmospheric Discharge

Russian Physics Journal - Experimental and theoretical investigations of a new form of pulsed periodic discharge burning in the form of a thin plasma jet – apokamp – have been carried...