Discharge Characteristics of Series Surface/Packed-Bed Discharge Reactor Diven by Bipolar Pulsed Power

The discharge characteristics of the series surface/packed-bed discharge(SSPBD)reactor driven by bipolar pulse power were systemically investigated in this study.In order to evaluate the advantages of the SSPBD reactor,it was compared with traditional surface discharge(SD) reactor and packed-bed discharge(PBD) reactor in terms of the discharge voltage,discharge current,and ozone formation.The SSPBD reactor exhibited a faster rising time and lower tail voltage than the SD and PBD reactors.The distribution of the active species generated in different discharge regions of the SSPBD reactor was analyzed by optical emission spectra and ozone analysis.It was found that the packed-bed discharge region(3.5 mg/L),rather than the surface discharge region(1.3 mg/L) in the SSPBD reactor played a more important role in ozone generation.The optical emission spectroscopy analysis indicated that more intense peaks of the active species(e.g.N_2 and OI) in the optical emission spectra were observed in the packed-bed region.     

Analysis of Power in an Argon Filled Pulsed Dielectric Barrier Discharge

In this paper an argon filled coaxial dielectric barrier discharge (DBD) has been studied to understand the detail of power transfer from a unipolar square pulse to plasma during discharge. A dielectric barrier discharge based diffuse pulse discharge and its electrical characteristics are investigated. A quartz coaxial DBD tube filled at different pressures is used in the experiment. A unipolar pulse voltage of different peak voltages and frequencies has been applied to the discharge electrodes for the generation of microdischarges. Two current pulses are used for two consecutive discharges per applied voltage pulse. The second discharge, which occurs at the falling flank of the voltage pulse, is induced by the charges stored on the dielectric barrier during the first discharge. It has been deduced that the power supplied to ignite the first discharge is partly stored to ignite the second discharge when the applied voltage decays. This process ultimately leads to much improved power transfer to the plasma. The knowledge obtained from dynamic processes of the DBDs in the discharge gap explains quantitatively the mechanism of ignition, development and extinction of the DBDs.     

Equation of Energy Injection to a Dielectric Barrier Discharge Reactor

The electric energy injection from a pulsed power supply to a planar type of dielectric barrier discharge(DBD) reactor at atmospheric pressure was studied. Relations of the energy injection with barrier materials, barrier thickness, peak voltage, gap distance, electrode area,and operation temperature were experimentally investigated. The energy injection is a function of relative permittivity, barrier thickness, peak voltage, gap distance, and electrode area. The influence of operation temperature on energy injection is slight in the range of 27–300℃ but becomes obvious in the range of 300–500℃. A model was established using which the energy injection can be easily predicted.     

Nanosecond Repetitively Pulsed Dielectric Barrier Discharge in Air at Atmospheric Pressure

Dielectric barrier discharge （DBD） between two cylindrical glass containers with salt water generated by a nanosecond repetitively pulsed power generator is rep...     

Improving Hydrophobicity of Glass Surface Using Dielectric Barrier Discharge Treatment in Atmospheric Air

Non-thermal plasmas under atmospheric pressure are of great interest in industrial applications, especially in material surface treatment. In this paper, the treatment of a glass surface for improving hydrophobicity using the non-thermal plasma generated by dielectric barrier discharge （DBD） at atmospheric pressure in ambient air is conducted, and the surface properties of the glass before and after the DBD treatment are studied by using contact angle measurement, surface resistance measurement and wet flashover voltage tests. The effects of the applied voltage and time duration of DBD on the surface modification are studied, and the optimal conditions for the treatment are obtained. It is found that a layer of hydrophobic coating is formed on the glass surface after spraying a thin layer of silicone oil and undergoing the DBD treatment, and the improvement of hydrophobicity depends on DBD voltage and treating time. It seems that there exists an optimum treating time for a certain applied voltage of DBD during the surface treatment, The test results of thermal aging and chemical aging show that the hydrophobic layer has quite stable characteristics. The interaction mechanism between the DBD plasma and the glass surface is discussed. It is concluded that CHa and large molecule radicals can react with the radicals in the glass surface to replace OH, and the hydrophobicity of the glass surface is improved accordingly.     

Numerical Study of Pulsed Dielectric Barrier Discharge at Atmospheric Pressure Under the Needle-Plate Electrode Configuration

In this paper,we study the characteristics of atmospheric-pressure pulsed dielectric barrier discharge (DBD) under the needle-plate electrode configuration using a one-dimensional self-consistent fluid model.The results show that,the DBDs driven by positive pulse,negative pulse and bipolar pulse possess different behaviors.Moreover,the two discharges appearing at the rising and the falling phases of per voltage pulse also have different discharge regimes.For the case of the positive pulse,the breakdown field is much lower than that of the negative pulse,and its propagation characteristic is different from the negative pulse DBD.When the DBD is driven by a bipolar pulse voltage,there exists the interaction between the positive and negative pulses,resulting in the decrease of the breakdown field of the negative pulse DBD and causing the change of the discharge behaviors.In addition,the effects of the discharge parameters on the behaviors of pulsed DBD in the needle-plate electrode configuration are also studied.     

The Experimental Investigations of Dielectric Barrier Discharge and Pulse Corona Discharge in Air Cleaning

The dielectric barrier discharge (DBD) and pulse corona discharge(POD) plasmagenerator was used to remove NHa, H2S, C7H8 etc. from atmosphere. The principle and charac-teristic of the two ways was discussed in the article. The test shows the result of PCD is betterthan that of DBD.     

Effects of Oxygen Concentration on Pulsed Dielectric Barrier Discharge in Helium-Oxygen Mixture at Atmospheric Pressure

In this work the effects of O_2 concentration on the pulsed dielectric barrier discharge in helium-oxygen mixture at atmospheric pressure have been numerically researched by using a one-dimensional fluid model in conjunction with the chosen key species and chemical reactions.The reliability of the used model has been examined by comparing the calculated discharge current with the reported experiments. The present work presents the following significant results. The dominative positive and negative particles are He_2~+ and O_2~-, respectively, the densities of the reactive oxygen species(ROS) get their maxima nearly at the central position of the gap, and the density of the ground state O is highest in the ROS. The increase of O_2 concentration results in increasingly weak discharge and the time lag of the ignition. For O_2 concentrations below 1.1%,the density of O is much higher than other species, the averaged dissipated power density presents an evident increase for small O_2 concentration and then the increase becomes weak. In particular,the total density of the reactive oxygen species reaches its maximums at the O_2 concentration of about 0.5%. This characteristic further convinces the experimental observation that the O_2 concentration of 0.5% is an optimal O_2/He ratio in the inactivation of bacteria and biomolecules when radiated by using the plasmas produced in a helium oxygen mixture.     

吹气对喷嘴板脉冲萃取柱脉冲振幅测量的影响

实验考察了5个喷嘴板脉冲萃取柱系统吹气条件下的真实振幅与表观振幅之间的关系。实验结果表明：在吹气条件下，由于吹气系统及脉冲萃取柱内气体被压缩，吸收掉了脉冲腿中部分液体的体积变化，使实验测量的柱内真实振幅值与无吹气条件下计算的真实振幅值间的偏差加大。     

Ozone generation enhanced by silica catalyst in packed-bed DBD reactor

In this paper, three dielectric barrier discharge(DBD) configurations, which were plain DBD with no packing, DBD with packed pure quartz fibers and DBD with packed loaded quartz fibers, were employed to investigate the effect and catalytic mechanism of catalyst materials in a packed-bed ozone generator. From the experimental results, it was clear that the DBD configuration with packed pure fibers and packed loaded fibers promotes ozone generation. For the packed-bed reactor, ozone concentration and ozone yield were enhanced by an increase of electric field in the discharge gap with the packed-bed effect. Meanwhile, the enhancement of ozone concentration and yield for the DBD reactor packed by loaded fibers with silica nanoparticles was due to the catalysis of silica nanoparticles on the fiber surface. The adsorption of silica nanoparticles on the fiber surface can prolong the retention time of active species and enhance surface reactions.     

Surface Modification of Polyimide Film by Dielectric Barrier Discharge at Atmospheric Pressure

In this paper,polyimide(PI)films are modified using an atmospheric pressure plasma generated by a dielectric barrier discharge(DBD)in argon.Surface performance of PI film and its dependence on exposure time from 0 s to 300 s are investigated by dynamic water contact angle(WCA),field emission scanning electron microscopy(FESEM),and Fourier transform infrared spectroscopy in attenuated total multiple reflection mode(FTIR-ATR).The study demonstrates that dynamic WCA exhibits a minimum with 40 s plasma treatment,and evenly distributed nano-dots and shadow concaves appeared for 40 s and 12 s Ar plasma treatment individually.A short period of plasma modification can contribute to the scission of the imide ring and the introduction of C-O and C=O(-COOH)by detailed analysis of FTIR-ATR.     

Study on the Generation Characteristics of Dielectric Barrier Discharge Plasmas on Water Surface简

A new contact glow discharge electrode employed in this study. Because of the strong field the electrode and the water surface, glow discharge on the surface of water was designed and strength in the small air gap formed by plasmas were generated and used to treat waste water. The electric field distribution of the designed electrode model was simulated by MAXWELL 3D~ simulation software, and the discharge parameters were measured. Through a series of experiments, we investigated the impact of optimal designs, such as the dielectric of the electrode, immersion depths, and curvature radii of the electrode on the generation characteristics of plasmas. In addition, we designed an equipotential multi-electrode configuration to treat a Methyl Violet solution and observe the discoloration effect. The experimental and simulation results indicate that the designed electrodes can realize glow discharge with a relative low voltage, and the generated plasmas covered a large area and were in stable state. The efficiency of water treatment is improved and optimized with the designed electrodes.     

Investigation of Plasma Polymerized Maleic Anhydride Film in a Middle Frequency Dielectric Barrier Discharge

Plasma polymerized maleic anhydride （MA） was carried out by using maleic anhydride supersaturated ethanol solution as a precursor in a dielectric barrier discharge （DBD）. The film properties were characterized by water contact angle （WCA）, Fourier transfer infrared （FTIR）, X-ray photoelectron spectroscopy （XPS）, atomic force microscope （AFM） analysis, and a thickness profilometer. The influence of the processing parameters on the film properties such as tile power frequency and polymerization zone was investigated. The results show that anhydride group incorporated into the growing films is favorable at the frequency of 80 kHz and working pressure of 50 Pa. The poly （maleic anhydride） film is uniform and compact at an average deposition rate of 8 nm/min.     

Dielectric Barrier Discharge Plasma-Induced Photocatalysis and Ozonation for the Treatment of Wastewater

The physicochemical processes of dielectric barrier discharge （DBD） such as insitu formation of chemically active species and emission of ultraviolet （UV）/visible light were utilized for the treatment of a simulated wastewater formed with Acid Red 4 as the model organic contaminant. The chemically active species （mostly ozone） produced in the DBD reactor were well distributed in the wastewater using a porous gas diffuser, thereby increasing the gas-liquid contact area. For the purpose of making the best use of the light emission, a titanium oxide-based photocatalyst was incorporated in the wastewater treating system. The experimental parameters chosen were the voltage applied to the DBD reactor, the initial pH of the wastewater, and the concentration of hydrogen peroxide added to the wastewater. The results have clearly shown that the present system capable of degrading organic contaminants in two ways （photocatalysis and ozonation） may be a promising wastewater treatment technology.     

Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma

In this study atmospheric pressure dielectric barrier discharge （DBD） plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/Ou, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 rain is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.     

脉冲萃取柱下澄清段的吹气法管道设计原则

本工作实验考察吹气管道体积对吹气法在线测量脉冲萃取柱真实振幅的影响。实验结果表明：当吹气管道总体积与吹气杯体积之比不大于4时,吹气法在线测量的真实振幅与表观振幅呈线性关系。同时,就满足乏燃料后处理中脉冲萃取柱下澄清段压降在线测量的吹气管道的要求进行了讨论。根据这一要求,确定了吹气系统的设计原则。     

Volume Diffuse Dielectric Barrier Discharge Plasma Produced by Nanosecond High Voltage Pulse in Airflow

Volume diffuse dielectric barrier discharge (DBD) plasma is produced in subsonic airflow by nanosecond high-voltage pulse power supply with a plate-to-plate discharge cell at 6 mm air gap length.The discharge images,optical emission spectra (OES),the applied voltage and current waveforms of the discharge at the changed airflow rates are obtained.When airflow rate is increased,the transition of the discharge mode and the variations of discharge intensity,breakdown characteristics and the temperature of the discharge plasma are investigated.The results show that the discharge becomes more diffuse,discharge intensity is decreased accompanied by the increased breakdown voltage and time lag,and the temperature of the discharge plasma reduces when airflow of small vclocity is introduced into the discharge gap.These phenomena are because that the airflow changes the spatial distribution of the heat and the space charge in the discharge gap.     

脉冲反应堆脉冲运行瞬态的子通道分析

为获得脉冲运行瞬态的堆芯温度场变化情况,本文开发了适用于低温、常压工况的脉冲反应堆瞬态热工分析子通道程序PRC-STAC。利用TRIGA MARKⅡ反应堆的瞬态参数对程序进行了验证,验证结果表明,二者符合较好。利用PRC-STAC程序计算了西安脉冲堆燃料元件和堆芯冷却剂的瞬态热工参数,并讨论了脉冲运行对燃料元件的安全影响。     

吹气法在线测量折流板脉冲萃取柱脉冲操作参数

在柱径为38、50和100mm的折流板脉冲萃取柱中，以30％TRPO煤油溶液和1mol/LHNO₃溶液为体系，研究吹气法在线测量脉冲萃取柱的脉冲频率和脉冲振幅。实验结果表明：吹气法所得的瞬时压降信号可准确确定脉冲频率，而瞬时压降信号的1个周期面积可确定脉冲振幅。峰面积值与脉冲萃取柱的板数和板开孔率参数成正比，与柱径和脉冲振幅成指数关系。在此基础上，得出了30％TRPO煤油/1mol/LHNO₃体系脉冲振幅的经验关联式，并在两相流条件下得到了验证。     

Experimental Study on Inactivation of Bacterial Endotoxin by Using Dielectric Barrier Discharge

The low-temperature plasma （LTP） generated by dielectric barrier discharge （DBD） was used to sterilize the E.coli endotoxin, which is usually difficult to kill ...