直流辉光和磁控增强放电等离子体的空间分辨发射光谱技术

光学发射光谱(OES)方法是等离子体诊断的有力工具之一,可以定量地给出等离子体的多种重要参数,如等离子体中的物种成分、粒子能态分布、激发温度、粒子相对密度等.本文介绍了一种用于电子回旋共振(ECR)微波等离子体磁控溅射靶附近的增强放电和直流辉光放电等离子体空间分辨诊断的发射光谱装置.其特点是光学收集系统的位置可以水平精细移动,因而可以对放电区域进行空间分辨发射光谱测量.作者利用这套装置对氩气的ECR微波等离子体和直流辉光放电等离子体进行诊断.在ECR微波等离子体的下游区内氩离子谱线的发射强度很弱,主要是高激发态原子的辐射.在磁共振增强放电区,离子谱线强度有所增加但仍比原子谱线弱,类似于直流辉光放电正柱区的光发射特性.     

铬及铍表面辉光放电清洗的研究

本文对He辉光放电清洗后的铬（Cr）表面杂质去除情况和铍（Be）样品真空出气量变化进行了实验研究。使用场发射扫描电镜和表面质量测量仪对比观察了不同放电参数处理后的Cr样品表面，结果显示在放电功率为200～300W、放电室压强为1～10Pa、清洗时间为10-20min时可较好地清除表面杂质和降低表面粗糙度；对辉光放电处理前后Be样品出气情况的实验对比结果显示，清洗后1h内总出气量约降为清洗前的1／6。     

辉光放电增强聚丙烯电荷贮存性能的研究

采用ＳＦ６，Ｏ２和空气低温等离子体对双轴拉伸聚丙烯薄膜进行表面改性，考察了表面接枝对驻极性能的影响。表面电位被用作表征电荷贮存容量的参数，而热刺激电荷衰减的半值温度则是衡量电荷贮存稳定性的标志。     

HL—1M装置的氦辉光放电清洗的清除率研究

通过对ＨＬ－１Ｍ的氦直流辉光放电清洗（ＨｅＧＤＣ）的放电特点和清除效率的研究，发现环形真空室的对称性导致与阳极截面相对称的区域的场强很弱，使其阴极位降区的厚度远大于氦离子的平均自由程，严重影响辉光清除效率。提出采用多电极不对称阳极电位的辉光放电来提高清除效率。     

细长石英管内直流放电等离子体研究

利用朗缪尔双探针等离子体诊断方法, 研究了细长石英管内的低气压直流放电行为, 探讨了细长管空间内的放电条件对等离子体参数的影响规律。结果表明:通过提高放电功率和增加阴极数目可以有效的提高等离子体密度, 且当放电气压为100 Pa时, 电子密度最大, 本装置所测最大密度为1.03×10¹⁷m^-3;电子温度则随着放电功率和放电气压的增大而不断减小;放电距离越远, 对击穿电压要求越高, 分段式放电可以在较低的放电电压下, 对较远的电极距离实现直流放电。     

HL—1M的氦辉光放电清洗的清除率研究

通过对ＨＬ－１Ｍ的氦直流辉光放电清洗（ＨｅＧＤＣ）的放电特点和清除效率的研究，发现环形真空室的对称性导致与阳极截面相对称的截面的电场为零的中性截面，该截面及附近的场强很弱，使其阴极位降区的厚度远大于氦离子的平均自由程，严重影响辉光清除效率，提出２多电极不对称阳极电位一的辉光放电来提高清除效率；同时发现辉光清洗使氢分压比托卡马克放电的送氢量低一个量级以上，才能重复奶好的有辅助加料的托卡马克放电。     

辉光放电清洗效果的质谱分析

在辉光放电清洗的实验研究中, 应用质谱技术进行了出气分析,应用其结果对射频辉光放电清洗的效果进行评估.实验结果表明,质谱技术能准确地分析表面吸附气体的分压强,氦离子的轰击可去除以及置换出样品中的气体,氮气、氧气和油蒸气在辉光放电清洗后的出气量下降,有利于超高真空的获得和维持.     

辉光放电离子渗金属的等离子体发射光谱诊断

利用发射光谱法对离子渗金属中辉光等离子体的电子温度进行了诊断。实验以氮气为工作气体，通过对放电时氮离子两条特征谱线强度的相对标定，测量了电子温度随放电气压40Pa～80Pa和电压500V～1000～的变化。并探讨了电子温度随气压和电压变化的原因。结果表明，该放电为典型的反常辉光等离子体放电，电子温度在1eV～15eV之间变化，且随工作气压和电压的的升高迅速增大，这与实际观测的放电效果相符合，实验结果表明，发射光谱法是测量离子渗金属中等离子体参数的一种有效手段。     

常压辉光放电等离子体制备荧光碳纳米粒子

采用常压辉光放电等离子体制备了超细荧光碳纳米粒子。分别采用聚乙二醇(PEG)2000和聚乙烯吡咯烷酮(PVP)20000作为表面活性剂和表面修饰剂,利用辉光放电等离子体射流产生的大量高能电子等活性粒子分解乙醇溶液制备碳纳米粒子。采用透射电子显微镜和荧光分光光度计对生成物的形貌和荧光特性进行了检测。结果表明,生成物为石墨相的荧光碳纳米颗粒。随着反应时间的延长,生成物的荧光强度增强;采用PEG-2000修饰后产物的荧光强度比采用PVP-20000更强;丝状放电模式下生成物的荧光强度高于辉光放电模式。制备的碳纳米颗粒的荧光量子产率为46.58%。     

均匀介质阻挡放电处理提高聚合物薄膜表面亲水性的研究

用中等气压空气中均匀介质阻挡放电(DBD)产生的低温等离子体对聚甲基丙烯酸甲酯(PMMA)和聚碳酸酯(PC)两种聚合物薄膜进行表面改性,研究了DBD等离子体处理对两种材料表面亲水性的影响。通过接触角测量和表面能测量以及全反射傅里叶变换红外光谱等手段研究了等离子体处理前后PMMA和PC的表面特性。测量了不同功率密度下材料表面水接触角和表面能随处理时间的变化规律以及处理后的材料在空气中放置时的退化效应,并对改性的机理进行分析。结果表明,两种聚合物薄膜经DBD等离子体处理后,接触角随处理时间的增加而降低,表面能随处理时间的增加而增加,两者均在一定处理时间达到饱和值;增大均匀DBD处理的功率密度,利用更少的处理时间就能得到同样的处理效果。处理后的材料在空气中放置时会出现退化效应,但即使放置14d后材料表面水接触角仍远低于处理前的值。     

Improvement in the hydrophilic property of inner surface of polyvinyl chloride tube by DC glow discharge plasma

A DC glow discharge plasma was generated inside polymer tube at low pressure. The polyvinyl chloride (PVC) tube with 4 mm inner diameter and 50 mm length was treated by Ar plasma generated inside the tube. The hydrophilic property of the inner surface of the PVC tube was remarkably improved after the plasma treatment. The water contact angle of the inner surface decreased to 37° from 75° for the untreated sample as the treatment time increase to 30 min. The water contact angle of plasma-treated PVC tube decreases with increasing applied voltage, but increase with increase in working pressure. When the Ar plasma-treated PVC tubes are stored in air at room temperature, the contact-angles of the inner surface quickly increases and finally reaches a plateau value which is still considerably lower than the 75° for the untreated sample.     

Studying surface glow discharge for application in plasma aerodynamics

Surface glow discharge in nitrogen between two infinite planar electrodes occurring on the same plane has been studied in the framework of a diffusion-drift model. Based on the results of numerical simulations, the plasma structure of this discharge is analyzed and the possibility of using it in plasma aerodynamics is considered.     

Hydrogen-free nitriding of ZrTiAlV by double glow plasma discharge improving the wear resistance

A hydrogen-free nitriding method through double glow plasma metallurgy is exploited and a nitrided layer was formed on ZrTiAlV alloy. The nitrided layer was characterised through X-ray diffraction, optical microscopy, scanning electron microscopy and energy-dispersive spectroscopy techniques, as well as through Vickers hardness and friction and wear tests. Results showed that the nitrided layer is 580?µm thick, homogeneous and dense. It mainly consists of TiN, Ti₂N and ZrN phases. The hardness of the nitrided layer on the surface of the ZrTiAlV alloy is nearly 2.5 times higher than that of the ZrTiAlV substrate. The friction coefficient and wear resistance of the alloy considerably improved after nitriding.     

A criterion for electric field reversal in the negative glow region of a short DC glow discharge

A theoretical analysis is performed and simple analytical formulas are obtained for estimating the position of the point of electric field reversal in a short (without the positive column) dc glow discharge. Using these formulas, the position of the reversal point can be approximately determined from tabulated published data on the ionization coefficients for fast electrons in the field.     

Numerical simulation of stationary processes in glow discharge plasma

The problem of determining the parameters of a low-pressure stationary glow discharge is considered in application to the simulation and optimization of the process of modification of the surface of structural materials. A coupled system of nonlinear equations is formulated, which includes the equations for charged particle fluxes (with allowance for the drift and diffusion components) and the Poisson equation for the electrostatic potential. In order to study the influence of geometric factors on the physical characteristics of discharge, the problem is considered in the spherical and planar cases. The nonlinear boundary-value problem has been solved by a modified method of continuation with respect to a parameter. The influence of diffusion processes and the gas discharge geometry region on the physical characteristics of discharge is analyzed.     

Controlled orientation of fibers in a glow discharge plasma

We have experimentally studied the behavior of nylon fibers in a low-pressure glow discharge. The orientation of fibers deposited onto a substrate can be controlled by changing the direction of the transverse plasma density gradient. These experimental results can serve as a basis for the development of novel commercial technologies.     

Influence of the initial composition of a methane-argon mixture on the electricophysical parameters and plasma composition of DC glow discharge

High Temperature - The stationary parameters and composition of DC glow discharge plasma (p = 40–200 Pa, i = 30–70 mA) in CH4-Ar mixtures of different compositions have been studied by...     

Calculation of the electrode surface temperature in the normal glow discharge

The two-dimensional non-stationary heat conduction equation is analytically solved in the volume of the cylindrical cathode with the normal glow discharge spot at one of its ends. A system of equations connecting the cathode surface temperature in the spot after discharge ignition to the discharge cathode sheath parameters is formulated, and the temperature time dependence for discharge in helium is calculated, taking into account the influence of background gas heating on the spot radius.     

Numerical simulation of surface glow discharge in molecular nitrogen

The DC surface glow discharge in molecular nitrogen at a pressure p = 10 Torr and voltages V ₀ = 600, 700, and 1000 V is considered based on the diffusion-drift model. The local maxima of the electric field strength and the current density on electrodes are determined. The temperature fields induced by Joule heating in the near-electrode regions are analyzed.     

Plasma parameters and chemical kinetics of an HCl DC glow discharge

The investigations of plasma parameters and active particles kinetics in an HCl DC glow discharge system were carried out. The investigation combines plasma diagnostics by electric probes and plasma modeling based on the self-consistent solution of Boltzmann kinetic equation and the balance equation of chemical kinetic for neutral and charged particles. It was shown that the direct electron impact dissociation of the HCl molecules represents the main mechanism for the formation of the Cl and H atoms while the total balances for all kinds of neutral particles are noticeably influenced by the volume atom-molecular reactions. The analysis of the vibrational kinetics shows low population of the vibrational energy levels for HCl molecules, but the role of the HCl_V>0 in the negative ions formation process cannot be neglected. The assumption of the Eley-Rideal recombination kinetics for both chlorine and hydrogen atoms provides a good agreement between the calculated and experimental values of reduced electric field (E/N) and the total flux of positive ions.