重复频率纳秒脉冲介质阻挡放电对聚对苯二甲酸乙二酯表面改性

介绍了0.1 MPa下的纳秒脉冲介质阻挡放电(DBD)对聚对苯二甲酸乙二酯(PET)材料表面进行的亲水性改善。分别采用均匀和丝状放电模式对PET表面改性处理,并采用水接触角测量、原子力显微镜观察、X射线光电子能谱分析对改性材料进行表面分析。实验发现介质阻挡放电处理后PET表面水接触角明显减小,接触角从78°下降到25°,但随处理时间的增加有饱和效应;PET表面粗糙程度增加,亲水性含氧基团被引入,从而改善了材料表面亲水性;纳秒脉冲下的均匀DBD比丝状DBD处理效果更为显著。     

射频功率对辉光聚合物薄膜结构与光学性质的影响

采用三倍频射频辉光放电聚合技术,利用低压等离子聚合装置在不同功率条件下制备辉光放电聚合物(GDP)薄膜. 利用表面轮廓仪、Fourier变换红外光谱仪表征所制备薄膜在不同功率下的生长速率和化学结构, 讨论了功率变化对薄膜生长速度和化学结构的影响.利用元素分析仪和紫外可见光谱仪表征GDP薄膜中碳氢原子比和光学性质. 研究表明:薄膜的生长速率随射频功率的增大先增加后减少,功率为40 W时,生长速率可达到0.34 μm/h. 在波长大于500 nm的可见光区, GDP薄膜的光学透过率都在90%以上. GDP薄膜的光学间隙随射频功率的增大先减少后增加,射频功率为50 W时制备GDP薄膜的光学间隙最小.     

Uniformity analysis of dielectric barrier discharge (DBD) processed polyethylene terephthalate (PET) surface

A dielectric barrier discharge (DBD) plasma, operating in air at atmospheric pressure, has been used to induce changes in the surface properties of polyethylene terephthalate (PET) films. The effects that the key DBD operating parameters: discharge power, processing speed, processing duration, and electrode configurations, have on producing wettability changes in the PET surface region have been investigated. The approach taken involves the application of an Taguchi experimental design and robust analysis methodology. The various data sets obtained from these analyses have been used to studies the effect of the operating parameters on the surface uniformity and efficiency of the said treatment.In general, the results obtained indicate that DBD plasma processing is an effective method for the controlled surface modification of PET. Relatively short exposures to the atmospheric pressure discharge produces significant wettability changes at the polymer film surface, as indicted by pronounced reductions in the water contact angle measured. It was observed that the wettability of the resultant surface shows no significant differences in respect to orientation parallel (L-direction) or perpendicular (T-direction) to the electrode long axis. However, there was significant differences between the data obtained from these two orientations. Analysis of the role of each of the operating parameters concerned shows that they have a selective effectiveness with respect to resultant surface modification in terms of uniformity of modification and wettability. The number of treatment cycles and the electrode configuration used were found to have the most significant effects on the homogeneity of the resultant PET surface changes in L- and T-orientation, respectively. On the other hand, the applied power showed no significant role in this regard. The number of treatment cycles was found to be the dominant factor (at significance level of 0.05) in respect of water contact angle changes at the processed PET surface in both orientations. The driven metal electrodes (stainless steel or aluminium) were apparently superior to the driven dielectric electrode (ceramic or quartz) configurations. The grounded electrode in each case was a silicon rubber-covered aluminium plate (see later). The nature and scale of the surface changes that originate from the various processing conditions employed have been considered so as to determine the optimum treatment conditions in respect of processing outcomes, properties and any orientation dependence. Thus, it was revealed that higher processing speeds and longer processing durations are key for uniformity along the electrode axial orientation, while lower processing speeds and short exposure durations are key considerations, in the corresponding perpendicular orientation. In general, longer processing durations (low processing speeds and a high number of treatment cycles) and higher plasma powers induced greater changes in the surface wettability of the PET, as demonstrated by the observed water contact angles. This behaviour is taken to indicate that different combinations of DBD operating parameters and electrodes produce discharge conditions that can result in different plasma chemical processes in respect of uniformity, treatment efficiency and orientation dependence.     

用PET薄膜覆盖金属丝网电极实现大气压空气中均匀放电

将325^#不锈钢丝网电极和0.1 mm厚的PET薄膜紧贴在一起,平整地固定在Rogowski电极基座上,用50 Hz工频电压源及并联稳压电容,在大气压下2 mm空气间隙中实现了均匀放电.实验表明：将放电电流和电荷量波形作为判断放电均匀性的依据并不是完全可靠的,它只能判断放电在时间上的一致性,而不足以判断放电在空间上的均匀性.只有拍摄曝光时间不大于100ns的放电图像,才能可靠地判断放电的均匀性.在金属丝网电极覆盖PET薄膜的大气压气体放电实验中,这种放电图像被拍摄到,并说明大气压空气中的均匀放电只是汤森放电,而非辉光放电. 关键词： 大气压辉光放电 金属丝网电极 驻极体 高速摄影     

电容器薄膜等离子体表面改性实验研究

 建立了一套辉光放电等离子体对电容器薄膜进行表面处理的装置。采用N₂，O₂及Ar三种气体对聚丙烯、聚酯和聚苯硫醚膜进行了表面处理。红外光谱分析表明:薄膜表面的生成物与薄膜种类、气体种类和处理强度密切相关。场扫描电镜显示了薄膜表面的刻蚀现象明显。处理过的薄膜，非晶相被去除，球晶暴露。能谱分析说明了薄膜中C元素下降，N，O元素增加，但总体改变量很小。处理前后薄膜的直流击穿电压没有明显改变，但刻蚀过程造成的薄膜表面粗化可帮助电容器的浸渍过程更充分，从而可提高电容器的使用场强与储能密度。     

纳秒脉冲放电对聚对苯二甲酸乙二酯憎水改性

基于自主研制的ns脉冲电源(上升沿约70ns,脉宽约100ns)激励介质阻挡放电产生大气压低温等离子体,在CF4气氛下对聚对苯二甲酸乙二酯(PET)表面进行了憎水改性处理,测量了改性前后的薄膜表面的水接触角,给出了CF4气流量、放电电压、处理时间和CF4比例等参数对改性效果的影响规律。结果表明,大气压ns脉冲DBD表面处理能够实现PET材料的憎水性,改性后的PET表面水接触角由66°提高到最大100°。     

射频功率对辉光放电聚合物结构和性能的影响

采用辉光放电技术,利用三倍频射频电源制备了不同功率下的辉光放电聚合物(GDP)涂层.并对GDP涂层进行了傅里叶变换红外吸收光谱(FT-IR)和元素分析仪表征,讨论了功率变化对其内部结构的影响.利用热重法(TG)表征了GDP涂层在30—650 ℃范围内的热稳定性.结果表明:随着射频功率的提高,GDP涂层的沉积速率增大;SP³CH₃和联结甲基的乙烯基强度明显减小,SP³CH₂, SP²CH_{2 关键词： GDP涂层 红外吸收谱 热稳定性 射频功率}     

Amine-containing film deposited in pulsed dielectric barrier discharge at a high pressure and its cell adsorption behaviours

With monomer allylamine, amine-containing functional films were prepared in alternative current pulsed dielectric barrier discharge (DBD) at a high pressure. This paper analyses in detail the film properties and structures, such as hydrophilicity, compounds and microstructures as well as amine density by the water contact angle, Fourier transform infrared spectroscopy, atomic force microscopy, and ultraviolet--visible measurement. The influence of discharge parameters, in particular applied power, on amine density was investigated. As an application the cell adsorption behaviours on plasma polymerization films was performed in-vitro. The results show that at a high pressure pulsed DBD plasma can polymerize films with sufficient amine group on surface, through which the very efficient cell adsorption behaviours was demonstrated, and the high rate of cell proliferation was visualized.     

Combination of spark discharge and nanoparticle-enhanced laser-induced plasma spectroscopy

A combination of spark discharge and nanoparticle-enhanced laser-induced plasma spectroscopy is investigated. Depositing Au nanoparticles at the surface of a brass target can enhance the coupling of the target and the laser. More atoms in the brass sample are excited. As a secondary excitation source, spark discharge reheats the generated plasma, which further amplifies the enhancement results of nanoparticles. The spectral intensity with the spark discharge increases more obviously with nanoparticle concentration increasing than without the spark discharge. Also, plasma temperature and electron density are calculated by the Boltzmann plot and Stark broadening. The changes in the plasma temperature and electron density are consistent with the spectral emission changes.     

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.     

Characterization of a RF/dc-magnetron discharge for the sputter deposition of transparent and highly conductive ITO films

A RF-superimposed dc-magnetron sputter process for coating color filter materials with transparent and conducting ITO films was investigated. In this process, the sputtering cathode is excited simultaneously by dc- and RF-power (at 13.56 MHz). This work summarises the measured properties of the gas discharge. Some basic data of the deposited ITO films are given, also. The dependence of the RF portion of the total sputtering power on the discharge voltage has been monitored for different values of total power and process pressure. The ion energy distribution function of the positively charged ions approaching the substrate surface has been measured using a retarding field plasma analyser probe. It was shown that the mean energy of the ions increases with increasing RF portion of the total power. The electron temperature in the body region of the gas discharge has been derived from measurements of the optical emission of the excited species. Received: 3 November 1998 / Accepted: 8 March 1999 / Published online: 14 July 1999     

Mechanisms controlling the transition from glow silent discharge tostreamer discharge in nitrogen

Low-energy dielectric-barrier controlled discharges in nitrogen are studied by undertaking electrical measurements to determine mechanisms controlling the transition from glow to streamer-like discharge. The highest and the lowest values of the frequency and the amplitude of power supply voltage leading to a glow discharge have been found dependent on the gas flow and the nature of the surface in contact with the discharge. These boundary values have been related to the criteria necessary for initiating a Townsend breakdown rather than a streamer breakdown commonly observed under such conditions. This implies: (1) that the seed electron density just before the breakdown is high enough to allow the development of numerous small avalanches under a low field avoiding the formation of only one large avalanche mechanism at the origin of the streamer formation; and (2) to let the time for ions issued from the first avalanches to reach the cathode before the electrical field becomes large enough to induce the formation of large avalanches. Practically, the transition from a Townsend breakdown to a streamer breakdown is analyzed from electrical measurements data coupled to the visual aspect of the discharge. Without any gas flow, the obtaining of an atmospheric pressure glow discharge (APGD) is mainly limited by the species etched from the surface in contact with the gas. Indeed, these species can be quenchers of the nitrogen metastable molecules, which are the species at the origin of the formation of seed electrons via the Penning effect. This limitation can be overcome by the use of a laminar gas flow. However, this type of gas flow through the discharge induces a depletion of N₂ metastables and, consequently, influences the electron density at the entrance of the discharge, leading to a tendency on this part of the discharge to transit to a streamer-like one     

The sterilization of Escherichia coli by dielectric-barrier discharge plasma at atmospheric pressure

The sterilization of E. coli (ATCC8099) using an atmospheric pressure, air DBD plasma driven by 100 Hz high-voltage power supply was investigated in this paper. The results showed that germicidal efficiency was closely related to the plasma treatment time, the gap spacing, the initial cell density and the surface characters of substrate materials. The germicidal efficiency was 99.999% under the conditions of 5-min plasma treatment, 3-cm gap spacing and on PET films. After plasma exposure for 5 min, the temperature was observed below 43 °C which could not lead to inactivate E. coli. The observation of protein leakage and cell morphology alteration by transmission electron microscopy (TEM) techniques revealed that the etching action on cell membrane by electrons, ions and radicals was primary reason of DBD air plasma sterilization.     

Microtopography and field emission properties of carbon films grown in a microwave gas discharge plasma

Graphite-like carbon films are grown in an ethanol vapor plasma in a microwave gas discharge. The electrical parameters controlling the microtopography and electronic properties of carbon films are determined. It is shown that electron bombardment affects the fine structure of graphite-like nanocrystallites and their emissive power with characteristics close to those of carbon nanotubes. The emission properties of layered graphite-like films can be improved by metal (cadmium) impurity doping. For nanocrystalline graphite-like films, emission currents with a density of 0.3 A/cm² are induced at an electric field strength of less than 7 V/μ m in the gap. __________ Translated from Fizika Tverdogo Tela, Vol. 46, No. 2, 2004, pp. 367–371. Original Russian Text Copyright ? 2004 by Suzdal’tsev, Yafarov.     

Formation of a high-current pulsed gas discharge as a source ofhighly concentrated energy flux to treat metal surfaces

The properties of a novel, pulsed, high-current gas discharge with minimized energy losses are investigated. The discharge provides a highly concentrated energy flux that can be used to treat metal surfaces and to form thin surface layers with desirable properties. A theoretical treatment of the formation of the discharge is presented, and the limitations on its voltage and interelectrode separation length are considered. Experiments are carried out to test the theoretical predictions of the discharge parameters. The experimental results show that more than 80% of the energy input to the discharge from the power supply is delivered to the metal surface     

长脉冲等离子体放电下HT-7装置限制器温度变化及能流分析

 在HT-7托卡马克等离子体长脉冲放电过程中，作为直接面对等离子体的第一壁限制器表面的温度变化及其承受的能流密度的计算，对于判断限制器的作用和对等离子体的影响都有非常重要的意义。主要从测量到的距离限制器表面3mm处温度变化曲线,采用无限大平面模型计算限制器模头表面能量沉积的能流密度,并讨论了不同等离子体放电下局部点能流密度的差别。多数长脉冲放电下，少数局部点的温升超过1 000℃，最大能流密度超过10MW/m ²；但通过对等离子体位移的控制，局部点温升被抑制，高密度能流持续时间短，有利于长脉冲放电。同时对限制器结构和材料对模头温度的影响也做了比较详细的分析。     

Surface oxidation of a Melinex 800 PET polymer material modified by an atmospheric dielectric barrier discharge studied using X-ray photoelectron spectroscopy and contact angle measurement

Surface properties of a Melinex 800 PET polymer material modified by an atmospheric-pressure air dielectric barrier discharge (DBD) have been studied using X-ray photoelectron microscopy (XPS) and contact angle measurement. The results show that the material surface treated by the DBD was modified significantly in chemical composition, with the highly oxidised carbon species increasing as the surface processing proceeds. The surface hydrophilicity was dramatically improved after the treatment, with the surface contact angle reduced from 81.8° for the as-supplied sample to lower than 50° after treatment. Post-treatment recovery effect is found after the treated samples were stored in air for a long period of time, with the ultimate contact angles, as measured, being stabilised in the range 58-69° after the storage, varying with the DBD-treatment power density. A great amount of the C-O type bonding formed during the DBD treatment was found to be converted into the CO type during post-treatment storage. A possible mechanism for this bond conversion has been suggested.     

Modeling of the effect of a dielectric film on the electrode surface upon the discharge glow-to-arc transition

It is shown that when a dielectric film is on the cathode, the current density in the discharge sheath is raised due to the field emission of electrons from the cathode metal substrate under the effect of the electric field generated in the film by the surface charge that accumulates on it. This results in more intense cathode heating and faster glow-arc transitions.     

Surface diffuse discharge mechanism of well-aligned atmospheric pressure microplasma arrays

A stable and homogeneous well-aligned air microplasma device for application at atmospheric pressure is designed and its electrical and optical characteristics are investigated. Current-voltage measurements and intensified charge coupled device(ICCD) images show that the well-aligned air microplasma device is able to generate a large-area and homogeneous discharge at the applied voltages ranging from 12 kV to 14 kV, with a repetition frequency of 5kHz, which is attributed to the diffusion effect of plasma on dielectric surface. Moreover, this well-aligned microplasma device may result in the uniform and large-area surface modification of heat-sensitive PET polymers without damage, such as optimization in hydrophobicity and biocompatibility. In the biomedical field, the utility of this well-aligned microplasma device is further testified. It proves to be very efficient for the large-area and uniform inactivation of E. coli cells with a density of 103/cm~2 on LB agar plate culture medium, and inactivation efficiency can reach up to 99% for 2-min treatment.     

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。