Modeling Studies of the Formation and Destruction of NO in Pulsed Barrier Discharges in Nitrogen and Air

This paper presents the results of modeling studies on the formation and destruction of NO in pulsed barrier discharges in nitrogen and air. The goals of this work are to identify the major processes involved in the formation and destruction of NO in air discharges, to distinguish between oxidative and reductive paths for NO destruction, to explore the potential importance of excited state reactions, to evaluate the role of water in such systems, and to identify the final products in the absence of heterogeneous processes. In all cases, the systems were modeled with 100×10^–4% (100 ppm) of added NO, with and without 3% added water. The focus in all of this work is chemistry in the post-pulse regime.     

火花激发原子发射光谱分析不锈钢线材

火花激发原子发射光谱法应用于直径小于8mm的不锈钢线材的分析，对此类试样应用了一种特制的夹具，用块状标准样品制作工作曲线。由于线状试样和块状标准样品之间的形状差异所产生的系统不确定度借采用同类型标样作校正，对共存元素的相互干扰也采用了相应的校正方法。其它分析条件，包括严格的制样工序，氩气的纯度要求及其流量控制，以及光源的最佳条件等，作了深入的试验。按所提出的方法测定了不锈钢线材试样中碳、硅、锰、磷、硫、铬、镍及钛等8个元素。经校正后的结果与化学法测得结果相符。     

Concentrations of Active Species in the Flowing Afterglow of a Nitrogen Microwave Plasma

Measurements of nitrogen atom density, by means of NO chemical titration, along with an evaluation of the densities of some excited species N ₂ (B, v=11), N ₂ (B, v=2), N ₂ (C, v=0), and N ₂ ⁺ (B,v=0), by means of a spectroscopic study of some bands of dinitrogen, are achieved along the flowing afterglow of a dinitrogen microwave plasma (2450 MHz) for several pressures. The concentrations obtained are in the following range: [N]10 ⁺¹⁵ , [N ₂ (B, 2)]10 ⁺⁹ –10 ⁺¹⁰ , [N ₂ (B, 11)]10 ⁺⁸ –10 ⁺⁹ , [N ₂ (C, 0)]10 ⁺⁶ –10 ⁺⁷ , [N ₂ ⁺ (B,0)]10 ⁺⁶ -10 ⁺⁸ (cm^-3). From a kinetic study of the formation and decay of excited and charged species, an estimation of N ₂ (A, v), N ₂ (X, v, and N ₂ ⁺ (X) densities can be derived: [N ₂ (A, v)]10 ⁺¹² , [N ₂ (X, v6)]10 ⁺¹⁵ –10 ⁺¹⁶ , [N ₂ (X, v12)]10 ⁺¹⁴ –10 ⁺¹⁵ , [N ₂ ⁺ (X)]10 ⁺¹⁰ (cm ^-3 ).     

Formation of Negative Hydrogen Ions in a Ne–H2 Hollow Cathode Discharge

The formation of negative hydrogen ions in a conventional hollow cathode discharge has been investigated. A mixture of Ne and H₂ proved to be more advantageous compared to pure hydrogen. The study has been performed by solving the electron Boltzmann equation, coupled with a system of balance equations for neon and hydrogen neutral and charged particles. The vibrational distribution function of hydrogen has been calculated. Our calculations show unusually high population of vibrationally excited hydrogen molecules in a Ne–H₂ mixture, which explains the high density of negative hydrogen ions under optimal conditions (total gas pressure of few Torr, hydrogen number mole fraction of 1–10% and discharge current of 10–100 mA). Line intensities originating from highly excited neon states vs. hydrogen pressure have been calculated and a comparison with existing experimental results has been made.     

Investigation of glow discharge plasma for surface modification of polypropylene

Material surface properties of polymers, plastics, ceramics and textiles can be modified by atmospheric or low‐pressure glow discharge plasma. The aim of the present work is to study the surface modification of biaxially oriented polypropylene (BOPP) film in order to improve its hydrophilic and wetting properties. In this article we used low‐pressure, low‐temperature oxygen plasma for the surface treatment of BOPP. Scanning electron microscopy indicates that plasma treatment causes mainly physical changes by creating microcraters and roughness on the surface and increasing surface friction. Attenuated total reflectance infrared spectra show oxygen‐containing groups such as ? OH at 3513 cm^?1 and C?O at 1695 cm^?1. Microscopic investigations of water droplets on BOPP (treated, untreated) show that the interfacial adhesion of treated surfaces is increased. Copyright © 2003 John Wiley & Sons, Ltd.     

Kinetic model of a DC oxygen glow discharge

A simple kinetic model predicting the concentration of oxygen atoms, metastable singlet molecules O₂(a ¹) and negative ions O — in the positive column of a DC glow discharge is developed. The calculated O and O₂(a ¹) concentrations are compared to previously reported measurements for pressuresp=0.2–2 Torr and discharge currentsI=10–80 mA. The electron density calculated from the continuity equationj=n _e e v _d agrees well with experiment. The rate coefficients for electron impact processes used in the balance equations of O, O₂(a ¹), and O^– were taken from the literature as a function of the reduced electric fieldE/N forE/N=40–80 Td. A reasonable agreement is obtained between the model and the experiment with a set of 10 reactions for the production and destruction of the above-mentioned species     

Pt／钇稳定氧化锆固体电解质在高温下的电化学性质

用交流阻抗技术研究了二电极、三电极Ｐｔ／钇稳定氧化锆（简称ＹＳＺ）高温固体电化学体系．开路电位下，Ｐｔ／ＹＳＺ体系只有一个阻抗半圆，对应于电极体系的电化学活化控制过程，极化电阻随温度变化的表观活化能为１７１．５ｋＪ／ｍｏｌ．Ｐｔ／ＹＳＺ界面的双电层电容约为３００μＦ／ｃｍ２．阳极极化下，交流阻抗极化电阻显著减小；阴极极化下，极化电阻反而增大，并出现浓差控制现象．     

LSGMC5含量对于二甲醚燃料电池复合Ni-Fe阳极性能的影响

用浸渍法制备了掺杂不同质量分数的La0.8Sr0.2Ga0.8Mg0.15Co0.05O3-δ (LSGMC5)粉末的Ni8-Fe2-LSGMC5复合阳极, 并采用交流阻抗和直流极化技术考察了以氢气和二甲醚为燃气时该复合阳极的电化学性能及相应电池的功率输出特性. 结果表明, 在电极中掺入LSGMC5 粉末, 能显著地改善电极的形貌和电极/电解质界面结构, 减小欧姆电阻和极化电阻. 电极中LSGMC5 粉末含量对于氢气及二甲醚电化学氧化性能的影响显著不同. 以二甲醚为燃气时, 电极极化电阻随LSGMC5 粉末含量的增加而减小, 其中LSGMC5 掺杂量为30%的复合阳极具有最高的电化学性能, 相应电池在1073、1023、973 K 时的输出功率分别为1.00、0.61、0.40 W·cm-2; 以氢气为燃气时, LSGMC5 掺杂量为20%的复合阳极具有最好的电化学性能, 随着LSGMC5 掺杂量的进一步增加, 电极极化电阻显著增大.     

甲烷二氧化碳介质阻挡放电转化产物分布研究

针对介质阻挡放电甲烷二氧化碳转化实验,分析了反应的产物分布,探讨了进料组成和反应器结构对反应的影响.反应产物包括:高H2/CO摩尔比的合成气、气态烃、高辛烷值的汽油组分、醇和酸等含氧有机物.对所述电极结构,产物的选择性随碳数增加而降低;高的甲烷进料浓度有利于烃的生成,对醇和酸的最佳甲烷进料体积分数范围在67.4％～75.1％;放电间隙越小,原料转化率和烃、酸的选择性越大,大的放电间隙对醇的生成有利.     

Temperature-dependent dry etching characteristics of III–V semiconductors in HBr- and HI-based discharges

Microwave discharges of HBr/H₂/Ar and H/H₂/Ar with additional do biasing of the sample were used to etch InP, GaAs, and AlGaAs at temperatures between 50–250°C. The etch rates increase by factors of 3–50 and 5–9, respectively, for HBr-and HI-based discharges over this temperature range, but display non-Arrhenius behavior. The etched surfaces became very rough above 100°C for InP with either discharge chemistry due to preferential loss of P, while GaAs and AlGaAs are more tolerant of the elevated temperature etching. The near-surface electrical properties of InP are severely degraded by etch temperatures above 100°C, while extensive hydrogen in-diffusion occurs in GaAs and AlGaAs under these conditions, leading to dopant passivation which can be reversed by annealing at 400°C.