用发射光谱法测量氮气直流辉光放电的转动温度

本文报道了氮气气压分别为10和20Pa时，对直流辉光放电的发射光谱进行测量和分析的结果。选择的研究对象为N2放电中形成的N2^ B^2∑u^ →X^2∑g^ 跃迁的Δv=v′-v″=0谱带系中v′=0→v″=0谱带的R支。在阴极背面辉光区、阴极鞘层区、正柱区以及阳极辉光区中分别选择一点进行了转动分辨的发射光谱的测量。利用自己编写的光谱拟合程序，获得了相应的实验条件下N2^ 的转动温度，给出了转动温度随放电电压的变化趋势，其结果可以用直流放电的帕邢定律得到很好的解释。在10和20Pa气压下，放电的阴极鞘层区、正柱区、阳极辉光区中的转动温度都随放电电压呈现出了不同的变化趋势，甚至是完全相反的变化趋势。我们认为这是由于气压不同时，放电状态不同所致：气压为10Pa时的放电是正常辉光放电，而气压为时20Pa的放电为反常辉光放电。     

Two types of spherical stratified gas discharge

Results on experimental investigation of a volume low-pressure gas discharge between the walls of a metal chamber and the small anode in the center of the chamber are represented. The discharge current-voltage characteristics in the range of currents corresponding to Townsend and glow discharges are measured. The experiments were carried out in nitrogen, argon, helium, carbon dioxide, and argon-acetone mixture. Hysteresis of current voltage characteristics is observed for some gas media in the link area of Townsend and glow discharges. It is found that the Townsend spherical discharge plasma is always stratified. Contrary to the glow discharge, stratification in this case is observed in all gases and remains for an arbitrary length of time.     

针-板和针-水电极大气压直流辉光放电的光谱特性

利用光谱学方法,对针-水电极和针-板电极直流辉光放电特性进行了比较研究。结果发现两种装置产生的放电都有明显的分区现象, 从阴极到阳极分别为负辉区、阴极暗区、正柱区和阳极辉区。针-板电极放电中可以清晰地观测到阳极暗区, 而针-水电极放电阳极暗区不明显。对比两种放电的伏安特性曲线,发现放电电压均随电流增大而减小,但相同电流下针-水电极间的电压大于针-板电极间的电压。由于伏安特性具有负斜率,且放电电流密度介于10-5～10-4 A·cm-2,说明两种装置中的放电均处于正常辉光放电阶段。在正常辉光放电的范围内比较两种放电的发射光谱, 发现发射光谱中都包含N₂的第二正带系(含波长为337.1 nm的谱线)和N+₂的第一负带系(含波长为391.4 nm的谱线),但相对强度不同。利用光谱学方法对放电发射谱的谱线强度比I_391.4／I_337.1和振动温度进行了空间分辨测量,发现相同位置处针-水电极放电的谱线强度比要比针-板电极放电的大,并且相同位置处针-水电极放电的振动温度高。     

ELECTRON TRANSPORT BEHAVIOURS IN THE NITROGEN DIRECT CURRENT GLOW DISCHARGE

A Monte Carlo simulation is presented to describe the electron transport behaviours in the nitrogen direct current glow discharge. The energy and angular distributions of the electrons at different positions of the cathode dark space are calculated; their energy and density distribution features throughout the entire discharge are discussed. The influence of molecular vibrational excitation, typical for electron－molecule collisions, has been studied and the elementary process of active species generation has been illustrated. The simulated results reveal that, in the cathode dark space, the high-energy electrons are mainly forward scattering and behave as a high-energy ‘electron beam'. The sharp increase of the number of secondary electrons plays an important role in producing active species at the interface between the cathode dark space and the negative glow region. The vibrational excitation enhances the energy loss of electrons in the negative glow region.     

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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。     

DC atmospheric pressure glow microdischarges in the current range from microamps up to amperes

Electrical and spectroscopic results of comprehensive investigations of microdischarges in atmospheric pressure helium, argon, nitrogen and air at gaps less than 1 mm and over a large current range from microamperes up to amperes are presented. At distance shorter than 1 mm, electrodes influence the normal glow discharge structure and their electrical and optical parameters. Two oscillation discharge regimes were revealed in discharge current range comparable or less than the low-current limit of normal glow discharge.     

Formation of a volume discharge at a subnanosecond rise time of the voltage pulse

A study is made of the formation of a volume discharge in atmospheric-pressure air in a nonuniform electric field without additional preionization. It is shown that the spatial distribution of the plasma glow between a plane and a spherical (as well as a point) electrode at a subnanosecond rise time of the high-voltage pulse is volumetric in character. The change of the voltage polarity does not qualitatively affect the character of the glow. The propagation of a spherical ionization wave in nitrogen is calculated in the drift-diffusion approximation. The fact that the character of the discharge glow is essentially independent of the voltage polarity is explained by the multiplication of the background electrons in the dense working gas.     

Normal Glow Discharge: Comparison of Calculated and Experimental Data

Doklady Physics - The combined numerical and physical modeling of a glow discharge between plane disk electrodes in molecular nitrogen is performed at pressures р = 3 and 5 Torr. The...     

Investigation of thermal plasma generator of technological function

Experimental results on energy characteristics of electric-arc plasma generator for heating technical nitrogen with the power of up to 500 kW are presented. The features of arc discharge glow, thermal efficiency, and service life of the electrodes were determined under the regime of melting the metallurgical raw material in the test plasma electric furnace.     

N+2离子在氮直流辉光放电中碰撞离解的作用

采用氮辉光放电等离子体快电子和各种重粒子（N＋２，N＋，Nf）的混合Monte Carlo模型，从不同放电条件的离解碰撞率，快原子态粒子（N+，Nf）在阴极鞘层区的输运过程及轰击阴极的能量及角分布三个方面研究了 N＋２+N２→N+＋N+N2f反应在氮气直流辉光放电中的作用.该过程在电压较高时为阴极鞘层区的重要离解过程， 且主要发生在阴极附近，其碰撞率随电压和气压增加而增加；阴极表面附近的活性粒子（N＋，Nf）主要由该离解过程产生（而不是e--N2离解电离过程），而且这些粒子具有中等的平均能量且小角入射，是 关键词： 氮直流辉光放电 Monte Carlo模拟 N＋２-N２碰撞离解     

Interaction of a glow discharge with a rarefied hypersonic flow in a curvilinear channel

A two-dimensional simulation model is used to study the gasdynamic structure of a rarefied hypersonic flow of molecular nitrogen in a curvilinear channel in which the lower surface carries the cathode section of the discharge gap whereas the upper surface serves as the anode. The electrodynamic structure of the glow discharge (the distribution of concentrations of charged species, current density, and electric potential) is examined. It was demonstrated that the burning of a glow discharge in a rarefied hypersonic flow makes it possible to effectively modify the shock wave structure of the flow.     

氮气辉光放电阴极鞘层重粒子输运过程研究

采用蒙特卡罗模拟对氮气辉光放电等离子体阴极鞘层内离子(N₂⁺,N⁺)和快中性分子(N_2f)的输运过程进行了研究,计算了阴极鞘层中离子(N₂⁺,N⁺)和快中性分子的能量及角分布的空间变化,较好地解释了实验结果.得到了氮气辉光放电等离子体阴极附近主要存在着能量较低的荷能分子、密度较低的高能原子离子及密度和能量居中的分子离子.诸粒子状态随放电条件而变化.模拟结 关键词：     

To the kinetics and mechanism of magnesium nitridation in a dc discharge

The experimental study of magnesium nitridation simultaneously on the cathode, on the anode and in the positive column of dc nitrogen glow discharge at pressures 0·3 –5 Torr and currents 2–40 mA is presented. Main factors which affect the course of kinetic dependences are discussed. A scheme of possible reaction paths during both thermal and plasma film growth is suggested.     

Thermoluminescence and recovery processes in pure and doped NaCl after 20 K irradiation

The thermoluminescence (TL) spectra after X-ray irradiation at 20 K have been investigated for pure as well as divalent cation doped NaCl. The F-centre decay has also been determined in pure and Ca and Mg doped NaCl for comparison purposes. A clear decrease in F-centre concentration appears to correlate with glow peaks at 44 and 50 K for pure and Ca-doped samples. Main glow peak appearing at 69 K is not associated to any appreciable F-centre decay step. Below liquid nitrogen temperature (LNT) all peaks show both σ and π exciton emission bands. Above LNT, the glow peaks for doped samples show the σ emission together with another band at 410 nm, whereas pure samples still present the intrinsic emission bands.     

离子(N2+, N+)在氮辉光放电等离子体光辐射中的作用

采用氮辉光放电等离子体电子与重粒子综合的Monte Carlo模型,研究了离子(N2+,N+)与氮分子碰撞产生光辐射的强度分布及其 在氮辉光放电等离子体光辐射中的作用。两种离子产生的各种碰撞激发和辐射都分布在鞘层区内,光辐射强度向阴极方向逐渐 增加,且总强度随放电电压增加而增强。相对于电子产生的碰撞激发辐射,离子(N2+,N+)引起的辐射在阴极附近引起次最大 光强,且原子离子N+的作用较分子离子N2+大。当电压较低时,离子(N2+,N+)引起的辐射可以忽略。模拟结果很好解释了两 种典型的N2辉光放电光学发射谱的实验结果,为等离子体诊断研究中的光谱数据分析提供参考。     

Investigation of the glow and contracted discharge plasmas in nitrogen by coherent anti-Stokes Raman spectroscopy,optical interferometry,and numerical simulation

The translational temperature in the plasma of glow and contracted discharges is measured using the methods of coherent anti-Stokes Raman spectroscopy and optical interferometry. The current density in the discharge is determined by measuring the electron concentration with optical interferometry and emission spectroscopy. The distribution of nitrogen molecules over vibrational and rotational levels in the ground state, the electron energy distribution, and the time dependence of the gas temperature are numerically found based on a model including the homogeneous Boltzmann equation and balance equations for the concentrations of charged and excited particles and for the gas temperature. The dynamics of transition to the quasi-steady-state distribution of nitrogen molecules over vibrational levels is studied.     

氮等离子体枪中电子输运行为的蒙特卡罗模拟

采用蒙特卡罗模拟,对氮等离子体枪的两个环形电极间的氮气辉光放电过程中电子的输运过程进行研究.计算在不同平均电场与粒子数密度的比值(E/N)下,电子与氮分子发生不同碰撞的概率、出射电子的平均能量、方向角分布和电子的能量分布.结果表明,电子能量近似服从玻尔兹曼分布.随着E/N的升高,电子平均能量升高,发生激发、离化、电离和离化电离碰撞的概率增大;非均匀分布的电场使分子获得更高的离化率,同时显著增强出射电子的能量.模拟结果为等离子体应用设计提供了参考依据.     

Using corona and glow discharges for improving strength properties and corrosion resistance of steel

The effect of glow and corona discharges on the strength and physicochemical properties of steels has been considered. It has been found that the thickness of the hardened layer and the negative potential of the surface of the steel samples depend on the current intensity and the time of treatment in a corona discharge. The variation of the surface potential correlated with changes of the strength characteristics of steel. It has been shown that variation of the strength characteristics of steel after its treatment in a corona discharge was connected with a rearrangement of the defect structure. The variation of the strength characteristics of steel after its treatment in a glow discharge was due to implantation of nitrogen atoms in surface layers of the material.     

Electron energy distribution function in a hollow-cathode glow discharge in mixtures of nitrogen with electronegative gases

The electron energy distribution function (EEDF) in a hollow-cathode glow discharge in mixtures of nitrogen with electronegative gases is investigated. It is shown that small admixtures of SF₆ or CCl₄ to nitrogen significantly increase the number of electrons in the energy range 2–6 eV, which corresponds to the inverse part of the EEDF. In nitrogen with small admixtures of F₂ or NF₃, the EEDF differ slightly from that calculated for pure nitrogen. The EEDF in these mixtures substantially depends on electron attachment to electronegative gas molecules.