Characteristics of the Single-Gap Pseudospark Discharge Under Nanosecond Pulsed Voltages

In this paper, a single-gap pseudospark discharge chamber was built and tested with several electrode gap distances and pressures to explore the characteristics of the pseudospark under nanosecond pulsed voltages. Experimental results show that with the development of the discharge, anode plasma firstly forms near the anode, and then moves towards the cathode. The ionization initial voltage decreases with the increase of the electrode gap distance and pressure in our pseudospark discharge configuration. By analysing the emission spectra, it is concluded that the major emission spectra are composed of the second positive bands, and the electron energy of the plasma is in the level of several tens of electron volts. The mechanism of how the pressure and gap distance influence the characteristics has been discussed with the simulation of the collision ionization process using the Monte Carlo Collision method. Based on the simulation and experimental results, it is inferred that the breakdown voltages is decided by the ionization process of the electron with the neutral gas in the main gap, and a possible reason is put forward to explain the reason that U is a function of p ² d.     

低功率微波等离子体炬（MPT）光源基本性质的初步研究

对低功率微波等离子体炬(MPT)光源基本性质进行了初步研究,采用“双线法”测定了有、无样品引入时光源中激发温度随观测高度的变化;测定了Zn、Cd、Mg的原子线和离子线发射强度随观测高度的变化;还研究了一些实验参数对等离子体激发温度的影响。     

Extending the Capabilities of the Thermodynamic Simulation of Thermochemical Processes in Inductively Coupled Plasma Discharge

The capabilities of the equilibrium thermodynamic simulation of thermochemical processes in inductively coupled plasma discharge are considered. Using a quasi-equilibrium model, the formation efficiencies of singly and doubly charged ions of 84 elements are calculated within the temperature range 4000–10000 K with a step of 500 K. The results of the calculations can be used for improving the performance characteristics of semiquantitative analysis in inductively coupled plasma mass spectrometry. The main trends in investigations on further extending the capabilities of thermodynamic simulations in inductively coupled plasma atomic emission and mass spectrometries are outlined.OAO Ekaterinburgskii zavod po obrabotke tsvetnykh metallov     

电晕放电式低温等离子体电极结构优化

以恶臭气体氨气和硫化氢的降解率为考察指标,系统优化了电晕放电式低温等离子体设备电极间距、电极齿距、电极齿高三个参数。研究表明:氨气和硫化氢的降解首先随着电极间距和齿距的增加而增大,而后随着电极间距的进一步增大而逐渐降低,电极间距13 mm、电极齿距5 mm时具有最大的氨气和硫化氢降解率。当电极齿高7 mm时,氨气和硫化氢的降解率随电极齿高的增加而快速增大,当电极齿高7 mm时,其降解率随着电极齿高的进一步增大而缓慢增大,考虑到电极制作成本,故确定最佳电极齿高为7 mm。此外研究还表明,不同外施功率下,锯齿型(多齿型)的氨气降解率显著高于单一针尖型(单齿型)。     

Plasma Grooving System Using Atmospheric Pressure Surface Discharge Plasma

To fabricate narrow front contact grooves on a single crystalline silicon solar cell, we carried out etching of a silicon nitride film on a silicon substrate using the surface discharge plasma operated at atmospheric pressure. The control of groove width by changing the discharge voltage (V _d) and the length of a back electrode (l) used for formation of the surface discharge was examined. It was found that narrower electrode grooves could be obtained when l was short. For the case of l = 2 mm, the narrowest groove of 116 μm was obtained at V _d = 3.5 kV and the processing time (t _e) of 10 s.     

甲醇溶液辉光放电等离子体电解

甲醇溶液辉光放电等离子体电解过程出现明显的非法拉第定律现象, 主要产物是氢气和甲醛, 还有少量一氧化碳、甲烷、乙烷、丙烷、1,3,5-三噁烷和水等, 产物和产量受放电极性和辅助电解质及放电电压等因素的影响. 在甲醇溶液电导率为11.40 mS·cm-1, 放电电压700 V 条件下, 阳极气体产量为55.90 mol/(mol electrons), 阴极气体产量为707.90 mol/(mol electrons), 阴极气体产量是阳极气体产量的12.66 倍, 气相产物中氢气含量在86%(molar fraction)以上. 在等离子体层中甲醇分解过程和其它类型的等离子体分解过程类似, 蒸汽鞘层中的加速电子是引发辉光放电过程非法拉第定律现象的决定因素. 阴极辉光放电过程中等离子体-溶液界面上的主要活性物种是中性粒子和电子,阳极辉光放电过程中等离子体鄄溶液界面上的主要活性物种是中性粒子和正离子. 辅助电解质对产物的影响主要是通过影响界面上发生的后续反应过程来表现.     

辉光放电等离子体对合成甲醇用铜基催化剂的改性作用

以辉光放电等离子体方法制备了新型高效铜基催化剂, 应用XRD、SEM、H2-TPR、BET、H2-TPD、CO-TPD技术以及对CO加氢合成甲醇反应进行研究, 分析了在氮气、氢气或先氮气后氢气等方式的不同气氛中进行等离子体处理对铜基催化剂的结构和性能的影响. 结果表明, 催化剂前体经等离子体改性处理后, 样品的比表面积增大, 活性中心数增加; 当等离子体气氛为先氮气后氢气时, 催化剂上的CO加氢活性和甲醇的时空产率显著提高.     

放电等离子体技术在固态生物质聚合中的应用

本文介绍了高电压放电等离子体技术在生物质高分子聚合中的应用及机理,提出了把等离子体聚合技术应用于固体高分子生物质中,拓宽了等离子体聚合的应用范围及聚合产物的形态,讨论了在实现生物质等离子体聚合中,固体高分子原料聚合需要解决的问题,并就等离子体聚合在这方面的应用进展状况进行了扼要介绍,同时对其发展前景进行了展望。     

Characteristics and Analysis of the Mechanism of NO Removal in Dielectric Barrier Discharge Plasma by Hydrocarbons at Varying Temperatures

Theoretical analysis of the electron energy distribution function by the Boltzmann equation and experimental investigations into the effect of hydrocarbons (methane, acetylene and ethylene) on NO removal efficiency are presented at varying temperatures. The experiments were carried out using dielectric barrier discharge plasmas at 298, 363 and 403 K, respectively. Ethylene greatly enhanced NO conversion because of its stronger affinity for the O radical. NO conversion in the presence of methane and acetylene was much lower than with ethylene at all temperatures. With an increase in temperature, E/N increased, the molecular ionization strengthened and the electron mean energy increased, resulting in more active species generated through ionizing and exciting reactions at the same energy density. High-energy electrons accelerated the decomposition rate of hydrocarbons, and the rate constants of some major reactions were increased, producing more strong oxidizing radicals (HO₂). Therefore, NO removal efficiency was increased when the temperature was higher.     

Oxidation of Styrene in a Silent Discharge Plasma

A silent discharge plasma reactor has been developed to study the oxidation of styrene vapor in argon/oxygen mixtures. A number of analytical techniques were employed to determine the destruction efficiency and to characterize the intermediate products. The destruction efficiency was measured as a function of initial styrene concentration, temperature, and energy density of the plasma. The formation of solid products was observed in most experiments. At low temperature (100°C), the solid deposit was polymeric in nature, while at high temperature (300°C) the solid appeared to be amorphous carbon. A combination of high temperature and high energy density resulted in high destruction efficiency and minimal production of solid films. The destruction efficiency vs. energy density is shown to be more complex than a simple model predicting exponential behavior. Several reasons for the discrepancy are suggested. The e-folding energy density for the destruction of styrene is compared to literature values for other organic compounds, measured using similar types of plasma reactors.     

射频等离子体技术制备合成低碳醇用铜钴基催化剂

采用射频等离子体技术制备了CO加氢合成低碳醇用新型CuCo/ZrO2催化剂, 研究了等离子体气氛氮气、氢气和先氮气后氢气处理对催化剂结构和性能的影响, 并应用BET、XRD、XPS、TG和TPR技术对催化剂进行了表征. 与常规焙烧制得的样品相比, 射频等离子体技术制备的催化剂可有效抑制烃类生成, 提高总醇选择性, 大幅提高反应活性和低碳醇的时空收率. 表征结果显示, 等离子体技术使催化剂前驱体在低温下分解形成活性相, 显著提高了催化剂比表面积, 促进催化剂活性组分晶粒细化并提高其分散度, 催化剂表面的铜含量增加.     

微型辉光放电等离子体用于质谱成像分析的初步研究

本实验利用实验室自主研发的微型辉光放电等离子体(MFGDP)作为离子源解吸样品,使之离子化,得到样品的特征质谱图,经特定软件的转化即可得到对应的图像,图像表明,MFGDP用于质谱成像具有可行性.本方法具有装置简单、操作简易、等离子体羽低温、分析时间短(＜20 min)等优点,可同时定位样品中不同物质的空间分布.本研究探讨了影响质谱成像图清晰度的因素,优化了实验条件,在最优条件下,本方法的空间分辨率约300μm,对加有尿素的不同字迹进行初步质谱分析,并对冬枣切片中硬脂酸和槲皮素衍生物的空间分布做了影像探索.此技术可以根据化学物质的指纹图谱区分不同的字迹,也能够很好地获取样品中不同营养物质的分布状况,因此,为字画研究、艺术品鉴定、营养物质分布图的获取提供了一种新的方法.     

射频等离子体技术制备合成低碳醇用新型Cu-Co/SiO_2催化剂(英文)

采用射频等离子体技术制备新型Cu-Co/SiO2催化剂.与直接焙烧制备的样品相比,射频等离子体处理提高了催化剂的比表面积,显著增大了活性物种Co的表面含量,有效改进了催化剂的还原性能.以CO加氢合成低碳混合醇为模型反应,在563K,5.0MPa,6000h-1,V(H2)∶V(CO)=1.6的条件下,等离子体处理和等离子体处理后再焙烧样品比673K焙烧样品的催化活性提高30.46%和65.30%,低碳醇的时空收率分别提高58.22%和76.11%.     

Investigation of Hydrogen Peroxide Formation After Underwater Plasma Discharge

Plasma Chemistry and Plasma Processing - This paper reports investigations on the formation of hydrogen peroxide resulting from micro-pulse plasma discharges obtained in pin-to-pin configuration...     

辉光放电等离子体对聚丙烯纤维的表面改性

在对电晕、介质阻挡放电、γ射线辐射接枝对化纤改性的简要介绍基础上，重点论述了辉光放电等离子体对聚丙烯纤维的改性。并按等离子体技术的发展过程，对低压和常压辉光放电等离子体对聚丙烯纤维与织物改性的特点、原理及发展前景进行了扼要综述，指出常压辉光放电等离子体是一种很有潜力的表面改性技术。     

Determinations of Intermediate Neutral Species in Hydrocarbon Discharge Plasma

This work reports laser ionization combined with Time-Of-Flight (TOF) mass spectrometry investigation on intermediate species in the hydrocarbon plasma of atmospheric-pressure fast-flow pulsed dc-discharge. All neutral intermediate species including transient radicals from benzene/Ar discharge have been characterized by a molecular beam sampling combined with TOF mass spectrometry. This shows that with a hydrocarbon gas mixture of 0.3% C₆H₆ in Ar discharge the intermediate species consist of simple radicals (such as C₂, C₅H₅, C₇H₇) and polycyclic organic molecules (C₁₀H₈, C₁₃H₁₀, C₁₄H₁₀). Theoretical studies on total energies and ionization potentials of the intermediate species have been carried out using the hybrid density functional theory. Effect of the ionization potential on mass spectral intensity has been discussed. Based on the observed data, the possible major neutral reaction channels of the plasma chemistry have been discussed. The developed experimental method has implications in volatile organic compounds removing and impurities diagnosis in Tokamak edge-plasma.     

Kinetics of DC Discharge Plasma Polymerization of Hexamethyldisiloxane and Pyrrole

This paper investigates DC plasma polymerization kinetics by combining plasma parameters with film deposition rate in different conditions. The monomers hexamethyldisiloxane (HMDSO) and pyrrole were used. Both single and double Langmuir probes were used to measure the plasma parameters in pulsed power and continuous discharges. In order to avoid probe tip contamination, the probe was heated. Plasma density and electron temperature are reported. The electron current wave form is obtained in pulse power conditions. From the data, a plasma polymerization model is proposed. The conclusion is that the monomer molecules and free radicals adsorbed on the substrate surface react with activated sites produced by high energy ions bombarding the film, resulting in polymerization at the film surface.     

Softening Hard Water Using High Frequency Spark Plasma Discharge

Effects of high frequency spark plasma discharge as a time efficiency method in order to softening the natural hard water has been investigated experimentally. A very hard water sample with 331 ± 19 mg/l of CaCO₃ hardness was used. The current and voltage of each spike was about 9.6 A and 3.5 kV respectively at 16 kHz frequency with 35 μs pulse width. Hard water was treated for 2, 4, 6, and 8 min. The concentration of CaCO₃, Ca²⁺ ions, Mg²⁺ ions and pH as well as water conductivity was controlled before and after treatment. The concentration of CaCO₃ dropped by 70%, after 8 min treatment. During the treatment, the pH had a fluctuation about 1.5 and finally remained in neutral state. Also the elemental composition, crystalline structure and morphology of the precipitates were identified. Molecular dynamics simulation revealed that the ozone and hydroxyl play important roles in the softening of the hard water.     

Micro Plasma Generation Using Liquid Sampling-Atmospheric Pressure Glow Discharge

In open air and without any type of inert gas, stable and bright micro plasma was successfully obtained using Liquid Sampling Atmospheric Pressure Glow Discharge (LS-APGD). The discharge current varied between 20 to 80 mA with a maximum voltage 550 V, discharge gap 0.5–2 mm and solution pH of 1. The produced plasma operates in the normal glow discharge region at a low power (11–40 W). For analytical application the linear dynamic range is obtained up to 500 μg mL⁻¹. Limits of detection based on 3σ of the background intensity determined for Ca I (422.673 nm), Cu I (324.754 nm), Fe I (497.5 nm), and Zn I (213.856 nm) are 0.3, 0.65, 0.1, 0.7 μg mL⁻¹ respectively.