The Effect of Discharge Power on the Atmospheric Pressure Non-equilibrium Ar/O_2/TiCl_4 Plasma Deposition of TiO_2 Film

Deposition of TiO2 film from atmospheric pressure non-equilibrium Ar/O2/TiCl4 plasma was done to study the effect of discharge power during the film deposition process in this paper. TiO2 films with kinds of morphologies and controlled crystallization were deposited from mixtures of TiCl4 and O2 on quartz substrate by one step process. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to analyze the morphology and crystallization of the deposited TiO2 films. It was found that the discharge power played a key role in the morphology and crystallization of the deposited TiO2 film whether the flow of TiCl4 was large or small. When the flow of TiCl4 was large, the deposited TiO2 film was amorphous particles at low discharge power and was multi-crystalline at high discharge power. When the flow of TiCl4 [JP2]was small, the deposited TiO2 film became more compact and the crystallization was enhanced as the discharge power increased . The dependence of the discharge current and the applied voltage with the discharge power indicated that it was a glow discharge. The gas temperature which increases with the discharge power is one of the main causes that affect the morphology and crystallization of the deposited film.

Experimental Study of a Minitype Atmospheric Non-equilibrium Plasma Source

A mini-type of plasma source was studied experimentally. The results showed that the plasma density, which was generated by an atmospheric non-equilibrium plasma source, rises with the increase in driving electric-field and the momentum of gas particles. For a driving electricfield of 56 kV/cm and a gas particles＇ momentum of 10^9 × 10^-22 g·m/s, the ion density can exceed 10^10/cm^3 while the effective volume of the plasma source is only 2.5 cm^2. This study may help develop a method to generate a minitype plasma source with low energy consumption but high ion concentration. This source can be used in chemical industry, environmental engineering and military applications.

Study of Non-Thermal DC Arc Plasma of CH_4/Ar at Atmospheric Pressure Using Optical Emission Spectroscopy and Mass Spectrometry

Non-thermal C/H/Ar plasmas are widely applied to carbonaceous material production and processing.In this work,plasma parameters and gaseous species of the atmospheric non-thermal C/H/Ar plasmas produced by an atmospheric-pressure DC arc discharge generator in CH_4/Ar were investigated.The voltage-current characteristics were measured for different CH_4/Ar ratios.Optical emission spectroscopy was employed to analyze the electron excitation temperature,gas temperature and electron density under various discharge conditions.The hydrocarbon molecules produced in the CH4/Ar plasmas were detected with photoionization mass spectrometry.The optical spectral results demonstrated that the electron excitation temperature was 0.4-1 eV,the gas temperature was 2800-4200 K and the electron density was in the range of（5-20）×10^15 cm^-3.The mass spectrum indicated that a variety of unsaturated hydrocarbons（C2H4,C3H6,C6H6,etc.） and several highly unsaturated hydrocarbons（C4H2,C5H6,etc.） were produced in the non-thermal arc plasmas.

Polysilicon Prepared from SiCl_4 by Atmospheric-Pressure Non-Thermal Plasma

Non-thermal plasma at atmospheric pressure was explored for the preparation of polysilicon from SiCl4. The power supply sources of positive pulse and alternating current （8 kHz and 100 kHz） were compared for polysilicon preparation. The samples prepared by using the 100 kHz power source were crystalline silicon. The effects of H2 and SiCl4 volume fractions were investigated. The optical emission spectra showed that silicon species played an important role in polysilicon deposition

Bacteria Inactivation Using DBD Plasma Jet in Atmospheric Pressure Argon

A coaxial dielectric barrier discharge plasma jet was designed, which can be operated in atmospheric pressure argon under an intermediate frequency sinusoidal resonant power supply, and an atmospheric pressure glow-like discharge was achieved. Two kinds of typical bacteria, i.e., the Staphylococcus aureus （S. aureus） and Escherichia coil （E. coil）, were employed to study the bacterial inactivation mechanism by means of the non-thermal plasma. The killing log value （KLV） of S. aureus reached up to 5.38 with a treatment time of 90 s and that of E. coil up to 5.36 with 60 s, respectively. According to the argon emission spectra of the plasma jet and the scanning electron microscope （SEM） images of the two bacteria before and after the plasma treatment, it is concluded that the reactive species in the argon plasma played a major role in the bacterial inactivation, while the heat, electric field and UV photons had little effect.

Sterilization of Staphylococcus Aureus by an Atmospheric Non-Thermal Plasma Jet

An atmospheric non-thermal plasma jet was developed for sterilizing the Staphylococcus aureus （S. aureus）. The plasma jet was generated by dielectric barrier discharge （DBD）, which was characterized by electrical and optical diagnostics. The survival curves of the bacteria showed that the plasma jet could effectively inactivate 10 6 cells of S. aureus within 120 seconds and the sterilizing efficiency depended critically on the discharge parameter of the applied voltage. It was further confirmed by scanning electron microscopy （SEM） that the cell morphology was seriously damaged by the plasma treatment. The plasma sterilization mechanism of S. aureus was attributed to the active species of OH, N 2 ＋ and O, which were generated abundantly in the plasma jet and characterized by OES. Our findings suggest a convenient and low-cost way for sterilization and inactivation of bacteria.

Efficacy of Atmospheric Pressure Plasma as an Antibacterial Agent Against Enterococcus Faecalis in Vitro

Enterococcus faecalis （E. faecalis） is a microorganism that can survive extreme challenges in obturated root canals. The aim of this study was to evaluate the efficacy of a non-thermal atmospheric pressure plasma plume against E. faecalis in vitro. A non-thermal atmospheric pressure plasma jet device which could generate a cold plasma plume carrying a peak current of 300 mA was used. The antibacterial efficacy of this device against E. faecalis and its biofihn un- der different conditions was detected. The antibacterial efficacy of the plasma against E. faecalis and Staphylococcus aureus （S. aureus） was also evaluated. After plasma treatment, the average diameter of inhibition zone on S. aureus and E. faecalis was 2.62±0.26 cm and 1.06±0.30 cm, respectively （P 〈 0.05）. The diameter was increased with prolongation of the treatment dura- tion. The diameters of inhibition zone of the sealed Petri dishes were larger than those of the uncovered Petri dishes. There was significant difference in colony-forming units between plasma group and control group on E. faecalis biofilm （P 〈 0.01）. The transmission electron microscopy revealed that the ultrastructural changes eytoderm of E. faecalis were observed after treatment for 2min. It is concluded that the non-thermal atmospheric pressure plasma could serve as an effective adjunct to standard endodontie microbial treatment.

Investigation on the characteristics of an atmospheric-pressure microplasma plume confined inside a long capillary tube

An atmospheric-pressure microplasma plume of diameter 10 μm is generated inside a long tube. The length of the microplasma plume reaches as much as 2 cm. First, with the assistance of an air dielectric barrier discharge （DBD）, the ignition voltage of the microplasma decreases from 40 kV to 23.6 kV. Second, although the current density reaches as high as （1.2-7.6）× 10 4A cm-2, comparable to the current density in transient spark discharge, the microplasma plume is nonthermal. Third, it is interesting to observe that the amplitude of the discharge current in a positive cycle of applied voltage is much lower than that in a negative cycle of applied voltage. Fourth, the electron density measured by the Stark broadening of Ar spectral line 696.5 nm reaches as high as 3× 10 16 cm-3, which yields a conductivity of the microplasma column of around 48 S m-1. In addition, the propagation velocity of the microplasma plume, obtained from light signals at different axial positions, ranges from 1 × 10 5 m s-1 to 5× 10 5m s-1. A detailed analysis reveals that the surface charges deposited on the inner wall exert significant influence on the discharge behavior of the microplasma.

Generation of Atmospheric Pressure Plasma by Repetitive Nanosecond Pulses in Air Using Water Electrodes

Dielectric barrier discharge （DBD） excitated by pulsed power is a promising method for producing nonthermal plasma at atmospheric pressure. Discharge characteristic in a DBD with salt water as electrodes by a home-made unipolar nanosecond-pulse power source is presented in this paper. The generator is capable of providing repetitive pulses with the voltage up to 30 kV and duration of 70 ns at a 300 Ω resistive load. Applied voltage and discharge current are measured under various experimental conditions. The DBD created between two liquid electrodes shows that the discharge is homogeneous and diffuse in the whole discharge regime, Spectra diagnosis is conducted by an optical emission spectroscopy. The air plasma has strong emission from nitrogen species below 400 nm, notably the nitrogen second positive system.

Surface Treatment of Polyethylene Terephthalate Film Using Atmospheric Pressure Glow Discharge in Air

Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (PET) film surface for improving hydrophilicity using the non-thermal plasma generated by atmospheric pressure glow discharge (APGD) in air is conducted. The discharge characteristics of APGD are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena, and the surface properties of PET before and after the APGD treatment are studied using contact angle measurement, x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It is found that the APGD is homogeneous and stable in the whole gas gap, which differs from the commonly filamentary dielectric barrier discharge (DBD). A short time (several seconds) APGD treatment can modify the surface characteristics of PET film markedly and uniformly. After 10 s APGD treatment, the

Study of Gas Heating by a Microwave Plasma Torch

Among the different types of microwave plasma torches, the axial injection torch (TIA) has been used for several years to create chemically active species, in applications such as gas analysis, surface processing and gaseous waste treatments. The TIA allows the coupling of microwave energy (2.45 GHz) to a gas injected axially at the nozzle’s exit. The TIA produces non-local thermodynamic equilibrium plasmas with a high luminosity and a maximum density of charged particles at the nozzle’s exit. The present work is dedicated to study the plasma created by a TIA, running at atmospheric pressure. The study involves both experiment and modeling of this torch, in order to maximize the coupling between the microwave power and the plasma and to define the optimum plasma and flow operating conditions for plasma-to-gas heat transfer.

Quantum Theory of Disturbance and Delay of GPS Signals in <i>D</i>and <i>E</i>Atmospheric Layers: An Introduction

GPS signals play a very important role in the modern industry, science, tourism, military and domestic operations. However, GPS signals are not free from some mistakes caused by disturbances appearing in D and E layers of the atmosphere. A quantum approach is proposed to the theory of propagation of a satellite GPS signal through the D and E layers of the atmosphere, which reduces to the problem of scattering of photons moving in the electromagnetic field of a signal in Rydberg complexes formed in a two-temperature non-equilibrium plasma. The processes of creation of additional photons as a result of stimulated emission and resonance scattering of photons are considered. It is shown that the first process leads to a direct increase in the power of the received signal, and the second to a shift in the signal carrier frequency and the time delay of its propagation. This occurs because of the scattering of the Rydberg electron by the ion core and the neutral medium molecule in the intermediate autoionization states of the composite system populated by the strong non-adiabatic coupling of electron and nuclear motions.

The minimization of non-equilibrium plasma source at high pressure

The density of plasma produced by atmospheric non-equilibrium plasma source is the function of en-ergy dissipation rate in ionization electric field and gas particles momentum.The experiment shows that the plasma density highly rises with the increasing of energy dissipation rate and gas particles momentum.When the energy dissipation rate of activation field is 2.18 Wh/m3 and the average gas particles momentum is 109×10-22 g·m/s,the air throughput of plasma source whose volume is only 2.5 cm3 can be up to 12 m3/h and the density of plasma can be up to 1010 cm-3.The research can develop a method of producing minitype plasma source which is low energy consumption but high ion concen-tration used for chemical industry,environmental engineering and military.

大气压非平衡等离子体诊断:电场诱导二次谐波

电场诱导二次谐波作为一种非侵入式、时间分辨率高达纳秒甚至飞秒量级的测量方法在大气压非平衡等离子的电场诊断中得到广泛关注。基于二次谐波产生的原理,对其适用性进行了讨论。针对纳秒和飞秒激光器在该应用中的特点,搭建了对应的诊断系统。通过使用纳秒激光器测量电场,获得了更高的时间分辨率,并通过平行板电极产生的均匀电场对系统进行标定,获得二次谐波信号强度与电场强度平方的定量关系。基于该定量关系,最终获得大气压等离子体不同位置的瞬态电场。

Characteristics of Gliding Arc Discharge Plasma

A gliding arc discharge plasma and its characteristics are described. Analysis of the production principle of the plasma is presented. Some experimental results about two novel types of the gliding arc plasma generator have been obtained. These types of gliding arc plasma axe potentially usable in the chemical industry and environmental engineering.

脉冲电晕等离子体活化纯CO_2的反应

研究了在常温常压下，脉冲电晕等离子体对温室气体CO2的活化与转化分别考察了反应气体流速、脉冲电压峰值、放电频率对纯CO2转化的影响．结果表明，CO2主要分解为CO和O2，另有少量积碳和臭氧产生；随着反应气体流速的增加，CO2转化率、CO产率和选择性降低；随着脉冲电压峰值和放电频率的升高，CO2转化率、CO产率增大，CO选择性降低．

高气压强电场电离过程中的离子浓度分布规律

研究了高气压强电场电离区域的离子浓度分布的连续性方程,对电离区域的电离物的产生、消失和输运进行了研究。通过采用电离放电增加了输入能量密度、G值、电离占空比等,从而提高了离子产生率。通过外加电场和离子“雪崩”头部的本征电场的叠加作用,离子被束缚在放电通道中。对离子施加垂直电场方向的作用力,就能把电场中的等离子体成束输送出去。已经能够做到有效体积仅为1cm3的等离子体源,输运等离子体率达到1012cm-3.s-1。

强电场电离等离子体输运特性研究

运用连续方程和输运特性方程,对经济、军事和环境等领域急待解决的强电场电离等离子体输运问题进行了离子浓度分布的实验研究。高气压条件下强电场电离产生的离子若仅受外加电场和“雪崩”头部的本征电场作用,只会存在于放电通道中。对离子施加垂直电场方向的接近电场对离子的作用力,就能把放电通道中的离子从电场中输送出去。实验表明,有效体积仅1 cm3的等离子体源,其输运离子率可达到1012/(cm3.s)。

大气压Ar/H_2O等离子体射流的放电特性

为促进大气压Ar／H2O等离子体射流放电在材料表面改性、等离子体医学及环境工程等方面的应用，研究了大气压Ar／H2O等离子体射流放电模式和放电参量。测量了这种射流在不同外加电压下的电气特性、发光特性及光谱特性，并据此计算得到主要放电参量，如放电功率、传输电荷、电子激发温度、分子振动温度以及转动温度等随外加电压的变化规律。结果表明：随着外加电压的增大，大气压Ar／H2O等离子体射流放电模式可分为电晕放电、介质阻挡放电和射流放电3个阶段，并可通过电压电流波形图和发光图像进行区分。Ar／H2O等离子体射流产生的粒子主要有Ar、OH以及少量的O和N2等。随着外加电压的增大，放电功率、传输电荷及主要粒子（包括OH）的谱线强度都随着外加电压的增大而增大。当外加电压从7kV增加到9．5kV时，分子振动温度和转动温度随着外加电压的增大而增大，其变化范围分别为1000－2200K和350-550K。当外加电压为9．5kV时，电子激发温度为0．646eV。

脱硫脱硝技术展望

论述了脱硫脱硝技术现状 ,通过分析比较得出 :湿法脱硫投资和运行成本高 ,产生的副产品无法进行再利用 ;电子束烟气脱硫脱硝技术投资和运行比湿法脱硫低 2 0 %～ 30 % ,但需要严格庞大的放射线防护设施 ,电子加速器昂贵 ,电子能量损失大。笔者提出强电离放电可以将烟气中的SO2 氧化 ,然后生成固体微粒 (NH4) 2 SO4,提高反应速率 ,简化流程 ,有望真正解决我国的SO2 和NOx