分段表面放电沉积效率研究

利用一种结构紧凑的分段表面放电辐射源模块,详细研究了在不同电压、电容、气压实验条件下回路等效电阻、等效电感及放电能量沉积效率的变化规律,利用四分幅相机拍摄获得了不同实验条件下的放电等离子体通道图像,分析讨论了放电等离子体运动对放电能量沉积效率的影响,提出了提高能量放电沉积效率的有效途径。     

分段表面放电沉积效率研究

 利用一种结构紧凑的分段表面放电辐射源模块，详细研究了在不同电压、电容、气压实验条件下回路等效电阻、等效电感及放电能量沉积效率的变化规律，利用四分幅相机拍摄获得了不同实验条件下的放电等离子体通道图像，分析讨论了放电等离子体运动对放电能量沉积效率的影响，提出了提高能量放电沉积效率的有效途径。     

Excitation of metal spectra in combined glow discharge

Consideration is given to the special features of the excitation of spectra of metals (Ag, Au, Fe, Hg, Pt, and Sb) that manifest themselves in investigating spectral sources with combined glow discharge (glow discharge and capillary discharge). It is established that the proposed method for introducing a substance into a plasma makes it possible to realize two fundamentally different regimes: without evaporation and with complete evaporation and matrix atomization. It is shown that a spectral source of combined glow discharge with a nonequilibrium plasma has significant advantages for the most important analytical characteristics over quasi-equilibrium combined discharge at atmospheric pressure. The gold and platinum sensitivity in combined glow discharge is 10⁻⁷%, and the reproducibility of spectral determinations is 0.001–0.100, depending on the measurement range. A fractional separation of elements that makes it possible to analyze the phase composition of substances, particularly metals, with high sensitivity is revealed in glow discharge. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 2, pp. 143–147, March–April, 1997.     

Electrode system of the high voltage glow discharge for metal heating

The electrode configuration of the high-voltage low pressure glow discharge with a cylindrical cathode for producing the annular beam of electrons is studied in this paper. Supposing that the space charge density is equal to zero the distribution of the electric field in the region between the electrodes is determined. The distribution of the electric field governs the processes in the discharge.The authors would like to express their thanks to Dr. J. Horsák for carrying out the numerical calculations.     

液体电极上辉光放电丝的运动特性研究

大气压液体电极放电在生物医疗、化学降解、环境保护等众多方面具有广泛的应用前景,引起了研究者的关注.本文利用直流电压激励棒-水电极装置,在6 mm气隙间产生了大气压辉光放电.研究发现,随着电流的增大,放电由锥状转变成柱状,且此过程中水面上放电环的直径先增大后减小.利用高速照相机对放电进行研究,发现锥状放电是由单个放电丝旋转形成的.通过测量放电的伏安特性,表明放电处于正常辉光机理.利用光谱学方法,研究了不同电流下的振动温度、转动温度和谱线强度比I_(391.4)/I_(337.1),发现它们均随电流的增加而增大.根据气体放电理论,分析和解释了放电丝的运动机理,并对水面上放电环直径随电流的变化关系进行了解释.这些结果对于大气压液体电极放电的理论研究和实际应用均具有一定参考价值.     

Interaction of a surface glow discharge with a gas flow

A surface glow discharge in a gas flow is of particular interest as a possible tool for controlling the flow past hypersonic aircrafts. Using a hydrodynamic model of glow discharge, two-dimensional calculations for a kilovolt surface discharge in nitrogen at a pressure of 0.5 Torr are carried out in a stationary gas, as well as in a flow with a velocity of 1000 m/s. The discharge structure and plasma parameters are investigated near a charged electrode. It is shown that the electron energy in a cathode layer reaches 250–300 eV. Discharge is sustained by secondary electron emission. The influence of a high-speed gas flow on the discharge is considered. It is shown that the cathode layer configuration is flow-resistant. The distributions of the electric field and electron energy, as well as the ionization rate profile in the cathode layer, do not change qualitatively under the action of the flow. The basic effect of the flow’s influence is a sharp decrease in the region of the quasineutral plasma surrounding the cathode layer due to fast convective transport of ions.     

Time dependent argon glow discharge treatment of Al-alloy samples

Aluminium alloy ultra-high vaccum system provides a convenient tool to access the UHV region due to short pump down time, its reduced weight, low cost etc. For UHV systems, aluminium and its alloys are preferred materials to stainless steel. A cylincrical discharge chamber of SS 304 with various ports on it, evacuated by turbomolecular pumping unit is used in the experimental system. A hollow cathode de glow discharge in argon for different time durations is used to treat chemically cleaned ASA 6063 aluminium alloy samples, keeping all other parameters constant. The scanning electron microscope (SEM) is used to examine processed surfaces and to study topographical features. The energy dispersive microanalysis by X-rays (EDX) is used to determine the elemental composition of the samples. The results indicate the physical sputtering taking place in Ar GDC. The etched area increases with discharge time duration. The EDX spectrum shows the inconsistency in weight percentage of various elements of Al-alloy.     

Characteristics of surface glow discharge in a low-pressure supersonic gas flow

Kinetic particle-in-cell simulations are performed to examine the characteristics of the surface glow discharge in a supersonic nitrogen flow. The gas pressure is varied between 100 and 500 mTorr; the applied voltage, between −500 and −1000 V. The analysis focuses on the effect of boundary conditions at the dielectric barrier surrounding the electrodes on the electron energy distribution function. The potential on the dielectric is found by using a local balance condition for the electron and ion currents to the surface. The results of self-consistent simulations show that a negative potential on the dielectric substantially reduces the rate of high-energy electron loss from the bulk plasma and thus significantly changes the ionization rate, as well as plasma parameters and configuration.     

An XPS study of the KCl surface oxidation in oxygen glow discharge

The reaction between the surface of KCl and oxygen in a glow discharge has been studied by X-ray photoemission spectroscopy (XPS). Oxygen glow discharge treatment resulted in the formation of a superoxide, which decomposed under vacuum at room temperature to KO₂ and finally to K₂O. No evidence of KClO₃ or KClO₄ formation has been found. Binding energies of some oxygen species in potassium oxides were determined. The possible role of potassium in K-doped silver catalysts of ethylene epoxidation is discussed.     

The role of dissociative electron attachment to metal halides in a low-pressure glow discharge

The conditions are analyzed under which the dissociative attachment of electrons determines the properties of a nonequilibrium glow discharge plasma containing metal halides. The possibility of applying a simplified approach for the estimation of dissociative attachment and vibrational excitation cross sections of metal halides by combining quantum and semiclassical methods is discussed. By way of example, processes in a nonequilibrium Ar-SnI₂ plasma are analyzed in detail.     

Non-self-sustained hollow-cathode glow discharge for large-aperture ion sources

A discharge system is proposed in which an auxiliary gas discharge is used to inject electrons into the cathode cavity of a hollow-cathode glow discharge. A study is made of the region of stable existence of a non-self-sustaining hollow-cathode discharge. It is shown that the injection of electrons permits a reduction to <10⁻² Pa in the minimum pressure at which a discharge can exist. It is shown experimentally that this discharge can be used to generate wide-aperture ion beams. Zh. Tekh. Fiz. 67, 27–31 (June 1997)     

Characteristics of a glow discharge in atmospheric pressure air over the water surface

The current-voltage characteristics, the amount of cathode fall, and the spectra of plasma radiation from different spatial domains are presented versus the molecular band intensity of products arising in an atmospheric-pressure air glow discharge over the distilled water surface. The plasma electron temperature is also reported. The distance to a liquid cathode or anode is varied from 1 to 10 mm at a discharge mean current of 10–36 mA.     

Stability and energy efficiency of pulsed corona discharge in treatment of dispersed high-conductivity aqueous solutions

Pulsed corona discharge (PCD) is an energy-efficient method of water treatment, although its instability in treatment of conductive solutions showered onto the electrodes presents a problem. The impact of conductivity and gaseous ozone concentration on the discharge stability and the energy transfer efficiency was established. The discharge was stabilized by adjusting the voltage pulse shape. Energy dissipation increases with the treated solution conductivity due to ohmic losses reaching 30% of the energy delivered to the reactor at 45 mS cm⁻¹. The PCD energy efficiency and safety was improved by the modified electrode system design reducing the losses.     

Electrode design for a magnetically stabilized glow discharge

The operational characteristics of a magnetically stabilized glow discharge are investigated for several different experimental electrode configurations. In this parametric study, successive geometries were designed to accommodate and/or control specific aspects of the plasma glow process. In this manner, an electrode structure which optimizes discharge stability and promotes glow uniformity over an extended active volume, was ultimately achieved. The study teaches a promising new technique for significantly increasing the power density of high power gas lasers.Experimental data is in excellent correlation with predictions provided by a previous numerical study of this magnetic stabilization process.     

Energy model of glow discharge nitriding

A new model of nitriding is proposed on the basis of the energy initial conditions.     

氩直流辉光放电等离子体中电子运动及能量的模拟

采用自动调节时间步长的蒙特卡罗模拟,对平行板放电系统中的氩气直流辉光放电系统中的等离子体区内电子的运动过程进行了跟踪和抽样。统计结果表明:在我们的实验条件下,等离子体中的电子在电场作用下出现明显的轴向漂移;在40000次抽样中,出现能量为E的电子数目随能量E增大呈下降趋势,场强增大将引起能量分布展宽和电子平均能量增加;即使场强达到15V·cm-1,等离子体激发和电离仍是很少的;场强和气压都能明显改变电子的平均自由程。     

GDP/D-GDP化学结构与力学性能的研究

利用低压等离子体增强化学气相沉积技术制备碳氢辉光放电聚合物(GDP)和全氘代辉光放电聚合物(D-GDP)薄膜。利用表面轮廓仪、傅里叶红外光谱仪和纳米压痕技术对制备的样品进行表征,讨论了GDP/D-GDP薄膜的沉积速率、化学结构和力学性能在ICF物理实验用靶应用中的优缺点。结果表明:GDP/D-GDP薄膜的沉积速率都随反应气体流量比例近线性增加,GDP的沉积速率达到2.6μm,D-GDP的沉积速率达到1μm,GDP的沉积速率远大于D-GDP的沉积速率;D-GDP薄膜内部的交联化程度较弱,D-GDP更有利于靶丸内燃料的红外均化;GDP的力学性能明显优于D-GDP,更有利于ICF物理实验用靶的燃料填充与装配操作。