Abstract and Keywords of All Papers Presented to 6^th IEJ-ESA Joint Symposium

International Symposium on Electrostatics and Atmospheric Pressure Plasma Applications

(Followings are presentation number, title, authors, and their affiliations, abstract and keywords for each paper)

Session 1 “Particles”

8a-1 Limiting Factors in the Electrostatic Levitation of Fine Particles

G. S. P. Castle and Y. Wu

Department of Electrical and Computer Engineering, University of Western Ontario

It is well known that particles can be freely levitated in an electric field due to the charge induced on the particles by the external field. The charge depends upon the electric field strength and particle properties. This paper studies two important factors: particle shape and adhesion forces. An experimental apparatus was set up to collect the levitated particles in a filter contained in a Faraday pail and the charge-to-mass ratio (Q/M) was obtained based on the charge and mass measurements for the samples in the filter. Furthermore, the particle size was measured based on the shape analysis. In these experiments irregular shaped Al2O3 particles and spherical glass beads and copper particles with a sieve mean diameter of 138 mm were used and tested at different electric field strengths. By combining the results of the Q/M and size measurements, the charge per particle as well as the theoretical calculated value was calculated and compared for the different types of particles tested. It was found that for particles of the same sieve size at a fixed electric field, the particle shape and adhesion properties are two of the most important particle characteristics determining the magnitude of the induction charge on the particles.

K/W: electric field, induction charge, levitation, particle shape, adhesive force

8a-2 A Development of Atomized Powder Coating System and its Charging Characteristics of Powder

Particles

Mitsuru Matsui*, Takashi Takahashi** and Tsutomu Ito***

* Zao Electrostatic System Laboratory, **Top Industries, Co.,*** I. P. D., Inc.,

The paper describes a novel system of powder coating, named as atomized powder coating system, in which a newly designed powder atomizing unit, a powder mass flow rate controller and a powder conveying air flow rate controller have been installed. Generally, paint powder forms rough and large particles of agglomerate powder in the process of handling and storage, and such coarse particles cause to degrade the quality of coating film. The atomizing unit can break the agglomerate powder particles into fine pieces by a high speed sharing air flow spouted from a thin nozzle, that brings particle size distribution of the powder back to the original one given at the point of production. Atomizing the powder into discrete particles has allowed taking an accurate measurement of mass flow rate of powder, so that full automatic control of the system has been realized. Electric charging of the atomized powder particle has been extremely improved, and charge to mass ratio (Q/M) of a sample powder of an epoxy resin sprayed through a typical corona gun has been obtained as 0.35-0.15 micro-Coulomb/g under spraying 50-200 grams of powder per minute.

K/W: Electrostatic powder coating, Charge to mass ratio, Mass flow rate control, Particle size distribution, Atomized powder coating

8a-3 Three-Dimensional Electrohydrodynamics for Alternatively-Oriented Spiked-Electrode Electrostatic Precipitator

Toshiaki Yamamoto, Hidekatsu Fujishima, Yoshifumi Morita and Masaaki Okubo

Department of Energy Systems Engineering, Osaka Prefecture University

The three-dimensional electohydrodynamics (EHD) for alternatively oriented spiked-electrode electrostatic precipitator (ESP) was investigated. The secondary flow forms a pair of elliptic circulatory cells between spiked electrode along the wire and its direction was opposite to the point corona electrode configuration. When the primary flow exists, a pair of elliptic spiral flow is formed in the direction of the gas flow. The organized spiral motion disappears and turns to turbulent when the ratio of the spiked-electrode distance to the wire-to-plate spacing is less than 0.10.

K/W: electrohydrodynamics, EHD, corona wind, ionic wind, secondary flow

Session 2 ”Application”

8a-4 Plasma Actuators for Air Flow Control

Eric Morear and Gerard Touchard

Laboratoire d'Etudes Aerodynamipues (LEA), Bd Marie&Pierre Curie

The goal is to use a non thermal plasma as an air-moving actuator in order to control the airflow around obstacles, such as an airfoil to enhance lift or to reduce drag for example. This paper gathers several studies to give an overview of the characteristics of this type of actuator. For few years. the LEA has been working on this subject. This paper is divided in several pads. We first present the principle for a surface discharge actuator. Then we analyse two types of actuators : the surface corona discharge and the dielectric barrier discharge. For both, electrical behaviours and performances are presentcd. Finally an example on a NACAOOI5 airfoil profile is given.

K/W: Air flow control, Discharges, Plasmas, Actuators.

8a-5 How Electrostatic Applications Have Improved the Quality of Life

John F. Hughes

School of Electronics and Computer Science, University of Southampton

Our understanding and manipulation of charge separation processes have progressed substantially in the period between the first documentation by the ancient Greeks and the present day. While the concept of the existence of what has become labelled as “positive” and “negative” charge is in itself quite intriguing, what is perhaps more remarkable is that this ‘accidental’ discovery was to revolutionise civilisation as we know it. Separation of charge, coupled with the movement of charge, was to give birth to the vast new technologies of electronics and electro/magnetics. Without these, we would still be trapped in the age of coal, gas and steam. There would be no telephones, no radio and television, no inter-continental air travel, no space exploration and very primitive health care. One of the first commercial applications of controlled charge separation was for the generation of high voltage, with the Van de Graaff generator probably being the most well known and familiar. Although now only regarded mainly as museum curiosities, it was these types of electrostatic devices which made possible the generation of the sufficiently high voltages necessary for the creation of X-rays. This was to mark the beginning of electrostatic applications in health care. Environmental applications were soon to follow with the development of the electrostatic precipitator. High voltage and unipolar charge were to be used for removing hazardous airborne particles from the flue gases of coal fired power stations, and later in cement processing plants and public buildings. These are the well-established and traditional examples of how electrostatic technology has contributed to an improvement in the quality of our environment and health care. In recent years, however, there has been a rapid and significant rise in new and novel applications which promise to deliver even more benefits from the controlled manipulation of unipolar charge.

K/W: recycling, spraying, pest control, allergen, bacteria, denaturing

Session 3 “Biological”

8p-1 Dynamics of DEP Liquid Actuation in Viscous Fluid

Tomohito Ito1, Masahide Gunji2 and Masao Washizu2

1 Department of Maritime Technology, Toba National College of Maritime Technology, 2 Department of Mechanical Engineering, The University of Tokyo

The dielectrophoretic (DEP) force provides a controllable means for rapid movement and dispensing of liquid on a substrate. When energized, a volume of water placed at the end of a pair of co-planar electrodes forms a protrusion that runs along the electrode gap, and is subdivided into small droplets when the energization is removed. The evaporation from droplets, which is a serious problem for very small droplets, can be avoided by immersing the system into oil, but such a viscous medium much affects the dynamics of the liquid motion. In this paper, an analytical model is developed to describe the DEP liquid motion in viscous media, where the hydrodynamic viscous drag at the front and the side of the protrusion is taken into account. It is shown that the model gives a good prediction of liquid propagations in a wide range of the medium viscosity.

K/W: Dielectrophoresis, liquid actuation, viscosity, hydrodynamic model

8p-2 Influence of Pulsed Electric Field on Various Enzyme Activities

Takayuki Ohshima1, Tsuruki Tamura2 and Masayuki Sato1

1Department of Biological and Chemical Engineering, Gunma University, 2Molecular Biology Department, Reverse Proteomics Research Institute Co., LTD.

Effects of high-voltage pulsed electric field (PEF) on native and denatured enzyme activities were studied. When PEF was applied to various native enzymes, 105 to 120 % of initial enzyme activities were observed after PEF treatment. It was suggested that an activation of enzyme would be possible by PEF treatment. We attempted the refolding of denatured enzyme by using PEF. When PEF applied to peroxidase denatured by heat treatment, enzyme refolding was accelerated in PEF and 60 % of initial activity was observed after 11.7 kV/cm and 30 sec of PEF treatment although spontaneous refolding of this enzyme resulted in 40 % of initial activity.

K/W: PEF, enzyme, activation, inactivation, peroxidase

8p-3 Arraying DNA Fibers in Microstructure by Electroosmotic Flow

Kyohei Terao1, Hiroyuki Kabata2 and Masao Washizu1

1Department of Mechanical Engineering, The University of Tokyo, 2Horizontal Medical Research Organization, Kyoto University

Stretching of DNA fibers is a key technique in high-resolution gene location based on a direct observation of DNA hybridization or protein binding. We developed a micro chip for positioning of cells in an array, drawing DNA fibers out of cells, and anchoring the stretched fibers. The device is equipped with micro structures for positioning cells and suspending DNA fibers, together with four electrodes for creating electroosmosis of variable flow direction. The structure for cell positioning is an array of microfabricated pocket-like structures, whose dimension is chosen to accept only one cell at a pocket. The structure for suspending DNA fiber consists of periodically arranged arrays of pillars, whose surface is labeled with DNA-binding molecules such as poly-cations. Unidirectional electroosmotic flow (EOF) is used to collect the cells in the solution and feed them into pockets. Then the cells are ruptured, and DNA fibers are drawn out to be stretched by EOF. The stretched fibers are then made into contact with the pillars by changing the EOF direction, where the fibers are anchored due to the DNA binding agent. The process gives an array of DNA fibers, freely suspended without contact to the solid surface except at the pillars. Such a configuration is expected to enable the steric-hindrance-free on-chip observation of many DNA bybridization or protein binding events.

K/W: Electrostatic flow, Gene analysis, DNA, molecular manipulation, μ-TAS(micro-total analysis system)

8p-4 Recovery of Yeast Chromosomal DNA Molecules from Agarose Gel Using Electrophoresis and Electrolysis

Jun Komatsu, Kazunori Takashima, Shinji Katsura and Akira Mizuno

Department of Ecological Engineering, Toyohashi University of Technology

A manipulation technique of single-DNA molecule has been studied for genome analysis and observation of biological reactions at a single-molecule level. A manipulation of long DNA molecules is difficult without any damages to them because DNA molecules are very fragile in a solution. Especially, Ionger DNA molecules easily undergo fragnentation by mechanical stress in the solution. Although longer DNA molecules such as chromosomal DNA molecules are usually prepared in an agarose gel, called "gel-plug", to avoid such fragmentation, it is hard to manipulate the DNA molecules for biological experiments in the gel-plug. We proposed a new recovery method of DNA molecules to a solution accompanied by a coil-globule transition. DNA molecules are very condensed like wounded strings in globular state, so that they have more tolerance to mechanical stress than one in random-coil state. A solution containing polyethylene glycol (PEG) and some cations was employed as a globule-induce solution. Because cations which diffuse into agarose gel inhibit electrophoresis of DNA molecules, this method consists of two steps. First, DNA molecules were extracted from gel to PEG solution by electrophoresis. Globule-phase transition dose not occur in the solution but the solution has very high viscosity, so that sources of mechanical stresses such as convection were suppressed. Afier that, A13+ ions were supplied by electrolysis of aluminum electrode to cause globule-phase transition of DNA molecules in polyethylene glycol solution.

Session 4 “Surface Charge”

8p-5 Retention of Charge on a Sheet in Contact with a Ground Plane

Joseph M. Crowley

Electrostatic Applications

A charged sheet that contacts a ground plane at one edge will lose charge at a rate that depends on its size and sheet resistivity, and also on the angle with the ground. This situation is modeled analytically using a partial differential equation for the charge as a function of time and location. Solution of the equation shows that Inost of the charge loss is caused by the decay of the fundamental eigenvalue, and that higher order modes play very little role. This result leads to a simple engineering approximation for the exponential decay time. This expression is applied to an example of an electrostatic dust mop, but should be equally useful for similar situations, including the charging of clothing, footwear, food wrap, and rolls of plastic film.

K/W: Electrostatic, Charge, Decay, Sheet, Contact, Mop

Session 5 “Charge Behaviour”

8p-6 Reflectance Measurement of Carbon Fiber Flocked Surface

Yasuo Sekii, Tsutomu Isaka, Shoichi Hasegawa and Tomonao Hayashi

Chiba Institute of Technology

In the present research creation of surface by electrostatic flocking using carbon fiber pile was studied. Using an experimental set up having a pair of metal electrode with 5cm gap spacing, the carbon fiber flocked surface was created. Reflectance measurement of regular reflection against infrared rays，as well as the measurement of diffused reflection against ultraviolet and visible rays, were performed on the obtained carbon fiber-flocked surfaces. Using Fourier Transform Infrared spectrometer equipped with a device of regular reflection measurement, reflectance of regular reflection against infrared ray was carried out. The result demonstrated that the reflectance of carbon fiber flocked surface is less than 0.001. In addition to the measurement of reflectance of regular reflection, the measurement of reflectance of diffused reflection was also performed using UV/VIS/NIR spectrophotometer equipped with integral sphere against visible and ultraviolet rays. The results showed that the reflectance values less than 0.01 is obtainable on the carbon fiber flocked surface, which demonstrates that the electrostatic carbon fiber flocking is the most promising method of creating surface with very low reflectance value.

K/W: Electrostatic flocking, Light trapping effect, Carbon fiber, Reflectance

8p-7 Triboelectric Charging between the Same Toner Particles

Tatsuya Tada1, Yoshinobu Baba2 and Manabu Takeuchi3

1Graduate School of Science and Engineering, Ibaraki University, 2Materials&Process Development Center, Fuji-Susono Research Park, Canon Inc., 3Department of Electrical and Electronic Engineering, Ibaraki Univesity

Insulating mono-component magnetic toners are widely used for black-and-white electrophotographic systems. The electrophotographic image quality depends on the triboelectric charge of toner particles. There are mainly two triboelectric charging mechanism in the insulating mono-component magnetic toner development system. One is the triboelectric charge interaction between the toner and the developing roller, and the other is the interaction between the toner and the toner. It is important to clarify the details of these triboelectric interactions. However, there have been few studies on the triboelectric interaction between the toner particles. In this study, the influence of toner components at the toner surface on the triboelectric interaction between the toner particles was investigated experimentally by using several kinds of toner with different components. The results indicated that the toner could obtain some amount of triboelectric charge by mixing the toner particles with each other. The charge distribution of the toner with magnetite or silica was equivalent to that of the toner without magnetite or silica. Further, the charge control agent (CCA) extended the width of the charge distribution of the toner comparing with that of the toner without the CCA by interaction between the toner particles.

K/W: Triboelectric charge, Triboelectric charge distribution, Toner, Magenetite, Silica, CCA

8p-8 Charge Behavior of Potassium Salt Ionomers of Ethylene Copolymer

Nobuyuki Maki1,2, Hitoshi Tachino1and Yoshiro Tajitsu2

1 Technical Center, Du Pont-Mitsui Polychemicals Company Ltd., 2 Graduate School of Engineering, Kansai University

Our objective is to analyze the mechanism of electric charge behavior of potassium salt ionomers of ethylene co-polymer by space charge and dielectric measurements. First, we measured the space charge distributions of potassium salt ionomers of poly (ethylene methacrylic acid isobutyl acrylate) using the Pulsed Electro-acoustic Method. When positive dc voltage was applied to an electrode of the potassium ionomer sample, negative charges are produced and distributed complexly in the potassium ionomer sample. On the other hand, charge induced on the surface of the counter electrode was not observed. Next, we obtained the frequency spectra of complex permittivies of potassium salt ionomers of poly (ethylene methacrylic acid) from 20℃ to 100℃ and from 10 mHz to 10 MHz. We found a large dielectric relaxation of the potassium ionomer sample. From the presence of the characteristic space charge distribution andlarge dielectric relaxation, we speculate that there exists a microscopically inhomogeneous structure that affects ion transport processes in the potassium ionomer sample.

K/W: Ionomer; Space charge distribution; Frequency spectra

8p-9 Thermally Stimulated Surface Charge Decay Measurements in Polymer Powder Layers

Takao Sugihara and Manabu Takeuchi

Ibaraki Univ.

Charge to mass ratios of polymer powders play an important roll in electrophotography and electrostatic powder coating. We tried to improve charging characteristics of polymer powders in this study. Thermally stimulated surface potential decay (TSSD) measurements were carried out on polymer powder layers to investigate the charging mechanism of polymer powders. The trap depths in the polymer powders were calculated from the TSSD curves. The difference between corona charging and tribocharging were examined by the TSSD measurements. The influence of heat treatments, organic vapor treatments, acid treatments, etc. on the trap density and trap depth were studied.

K/W: TSCD, trap, coating powder

8p-10 Solid Oxide Thin Film Preparation by Pulsed Laser Deposition Method for Electrochromic Application

Toshikazu Ohkubo1, Fumiaki Mitsugi2 and Yukiharu Nomoto1

1Department of Electrical and Electronic Engineering, Oita University, 2Venture Business Laboratory, Oita University

The all oxide solid state ITO (Indium tin oxide) / LiyWO3-x / Li1-zMn2O4 / ITO stacked structure was deposited on the silica glass by pulsed laser deposition for its electrochromic application. A WO3-x is a typical electrochromic material. However, the Li1-zMn2O4 electrolyte thin films have Li deficiency (z). Then, we prepared Li doped WO3-x thin film on the Li1-zMn2O4 electrolyte thin film to increase the amount of Li. The amorphous LiyWO3-x thin film prepared at room temperature and in an oxygen pressure of 7 Pa got the color of blue due to the W6+ / W5+ mixture valence state. The ion conductivity of the amorphous Li1-zMn2O4 thin film was quite low, but the thin film was suitable for the electrochromic application compare to the crystallized thin film. We attempted to deposit ITO top electrode thin films at relatively low temperature to prevent the bottom layers from changing the properties. The ITO thin film deposited at room temperature and in an oxygen pressure of 5 Pa showed the relatively high transmittance and the usable conductivity. The transmittance at a wavelength of 750 nm for the ITO / LiyWO3-x / Li1-zMn2O4 /ITO stacked film changed from 50% to 80% by the applied voltage, while the transmittance at around 450 nm did not change. The blue colored electrochromic property could be observed for the all oxide solid state film.

K/W: Electrochromic, LiyWO3-x, Li1-zMn2O4, ITO, Pulsed Laser Deposition

Session 6 “Calculation”

9a-1 Model Computations in Electrostatics

Istvan Berta

Faculty of Electrical Engineering, Technical University of Budapest

Model computation is an effective tool not only for better understanding basic phenomena, but also to simulate integrated processes, to create new protection systems, to design new applications. The optimization of applications and technologies needs effective simulation and detailed verification. The results of the model computations and the data got from the practice have to be compared. Practical solutions are presented from both industrial and atmospheric electrostatics. The risk assessment in passive lightning protection (to avoid both primary and secondary harmful effects), the safe and cost effective prevention of electrostatic hazards and the economic use of electrostatics in electrostatic precipitation are all theoretically designed and practically operated based upon the result of model investigations. The models apply fuzzy logic (for risk assessment, for creating fault trees, for establishing automated diagnostics and control) and they use the data of lightning detection and localization systems. The data base is used for the novel approach namely the active lightning protection.

K/W: Electrostatic charging, hazards, electrostatic precipitaion, lightning protection, risk analysis, fuzzy expert system

9a-2 Numerical Model for the Distortion Dynamics of Water Droplets in Electric Field

K. Adamiak1 and J. M. Floryan2

1 Department of Electrical and Computer Engineering, The University of Western Ontario, 2 Department of Mechanical and Materials Engineering, The University of Western Ontario

A liquid droplet in an external electric field is elongated in the direction of the field lines and can eventually be disintegrated. The paper presents a numerical algorithm, which can be used to predict dynamics of the droplet distortion in a uniform electric field. The droplet shape is calculated by solving the Laplace-Young equation, which results from the balance of capillary and electric forces. The gravity and fluid viscosity have been neglected and an ideally conducting fluid has been assumed. An iterative technique is used: starting with a stationary spherical droplet the electric field is calculated and a new droplet shape is predicted. Then, the flow potential and the pressure distribution can be determined. For a given time step all these calculations are repeated until convergence is reached. Due to idealizing assumptions both the electric field and flow potential are governed by the Laplace equations, although with different boundary conditions. The Boundary Element Technique has been selected as a numerical tool, because discretization of the droplet surface only is required and this results in a relatively small algebraic system to be solved. This technique also handles very well open problems, what is important for the electric field simulation.

K/W: Droplet distortion, Electric field, Transient analysis, Electrohydrodynamics

Session7 “Charging and Discharging”

9a-3 Influence of Relative Humidity on Corona Discharge from a Metal Wire Particle with a Floating Potential

Yusuke Kudo and Yoshio Higashiyama

Faculty of Engineering, Yamagata University

A conductive particle existing in an electric field, which has floating potential, could cause corona discharge via a particle. Corona onset and breakdown voltage from a metal wire particle were investigated in detail under the conditions of the location of the particle and the various relative humidity. The particle with a diameter of 0.25 mm and a length of 6 mm was fixed at given positions between parallel-plate electrodes with a spacing of 20 mm, located in a constant humidity vessel. Influence of relative humidity on the corona onset voltage depends on the position of the particle. DC corona discharge occurred stably except when the particle was located at the proximity to the positive electrode. As a　result, ac corona discharge from the particle located in the intermediate region between the electrodes occurred stably. In a dc electric field, corona onset voltage in the higher humidity was larger than that in the lower humidity when the particle is closed to the either electrodes.

K/W: micro-gap discharge, relative humidity, wire particle, corona onset, floating potential

9a-4 Surface Flashover in a Micro-Gap between Foil Conductors on Printed Wiring Board

Yoshiaki Yamano and Yousuke Takaoka

Faculty of Education, Chiba University

Impulse flashover strength between foil conductors on printed wiring boards with and without backing electrode was measured in air at 20'C and 40-450/0RH. The smallest gap distance between the conductors on the board is 20um. The thickness of the board was 0.3mm or 0.8mm. The thickness of the foil conductor was 18~Lm or 6um. The electric field (Laplacian field) near the conductor edge was calculated by charge simulation method. The experimental results were discussed using the calculated results with the electric field: the flashover for the board without backing electrode occurs at the constant strength of the laplacian field on the foil conductor edge, which is independent of the gap distance; For the board with backing electrode, the flashover at the constant field strength occurs only in the case of positive application at 0.8rnm of board thickness; In the other cases, the laplacian field strength at the flashover increases with the gap distance, which results from the deposition of homo-charge on the board surface by the strong normal field cornponent. It was also found out that the flashover voltage in the area of the gap distance <lOOum is almost independent of thicknesses ofboard and foil conductor within the ranges of our study.

K/W: flashover, printed wiring board, backing electrode,small gap

9a-5 A Compact High Voltage Pulse Generator Using a Rotary Induction Airhole Sparkgap

Hong-Geun Lee, Seung-Hoon Lee and Jae-Duk Moon

School of Electronic and Electrical Engineering, Kyungpook National University

Smog, acid rain, global warming, and ozone depletion are preeminent environmental problems facing the world today. Nonthermal plasma techniques offer an innovative approach to the cost-effective solution of these problems. A pulsed corona discharge plasma technique offers the advantages of energy efficiency and capability for the simultaneous removal of coexisting pollutants. The key to success in the nonthermal plasma approach is to produce a corona discharge in which the bulk of the electrical energy goes into the production of energetic electrons, rather than into gas heating. A compact high voltage pulse generator with a rotary induction airhole sparkgap instead of a conventional rotary ball sparkgap has been proposed, and its feasibility as a compact high voltage pulse generator used as a low cost and small scale pulse generator for pulsed corona discharge type nonthermal plasma reactor has been investigated. Parametric studies showed that the proposed induction airhole sparkgap had very low breakdown voltage and reliable pulse repetition characteristics compared with the conventional rotary ball sparkgap.

K/W: High voltage pulse generator, Discharge plasma, Rotary sparkgap, Induction airhole type sparkgap, Airhole type sparkgap, Ball type sparkgap.

9a-6 Gas Temperature of Spark Discharge in the Air

Ryo Ono1, Masaharu Nifuku1, Shuzo Fujiwara1, Sadashige Horiguchi1 and Tetsuji Oda2

1Research Center for Explosion Safety, National Inst. Of Advanced Ind. Sci. and Technol. (AIST) 2School of Engineering, The University of Tokyo

The gas temperature of spark discharge is measured by spectroscopic analysis of the N2 second positive band emission, and the temperature after the discharge pulse is measured by laser-induced fluorescence of OH radical. The discharge is occurred in the air with the energy of 0.03 to 1 mJ. It is shown that the gas temperature during the discharge is about 450 K, while the vibrational temperature of N2 is about 5000 K. Those temperatures are independent of discharge energy. After the discharge extinction, the gas temperature increases for several microseconds up to 800 to 1200 K. It indicates that the gas is heated even after the discharge. Then the temperature decreases to room temperature at a rate of 8 to 35 K/us.

K/W: electrostatic discharge, ignition, spark discharge, gas temperature

9a-7 Development of Electrode for Removing Pollutants in Soil by the Natural Zeolite and its Characteristics

Masafumi Suzuki1, Tomoyoshi Shoji2 and Noboru Yoshimura1

1 Department of Electrical and Electronic Engineering, Faculty of Engineering and Resource Science, Akita University, 2 Department of Materials-process Engineering and Applied Chemistry for Environments, Faculty of Engineering and Resource Science, Akita University

Recently, the pollution of the soil by heavy metal elution from industrial effluents, becomes serious with the development of the industry. Many techniques on the processing of the polluted soil such as the diffusion prevention, the elution prevention, the extraction and the removal, the decomposition and the decontamination, were proposed. Recently, the technique using the electrokinetic phenomenon is noticed. In this method, ionized heavy metal which is included for contaminated soil moves to cathode side with the water by the electroendosmose and discharged from soil. However, the recovery efficiency of heavy metal does not rise, when the recovery of the drainage is not perfect. In addition, there is danger of the secondary pollution by the drainage. We noticed the natural zeolite in order to solve this problem. The natural zeolite is used as cathode, and the heavy metal ion under drainage is adsorbed it. The natural zeolite large exists as resources in the inland and has the very high ion adsorption. However, the natural zeolite is an insulator, therefore, it is not possible to use for the electrode. In this study, the electrode which mixed the carbon in natural zeolite was produced, and the electrical characteristic and metal ion adsorption were measured.

K/W: Removing Pollutants, Natural Zeolite, Electrokinetic phenomenon

Session 8 ”Safety”

9p-1 Testing Products and Processes with Regard to Electrostatic Hazards

Ulrich von Pidoll

Physikalisch-Technische Bundesanstalt

In the past few years a rapid development in products intended for use in explosive atmospheres has taken place. More and more products appear on the market which have specially treated surfaces or high-voltage devices coupled to microprocessor control systems. For this reason, methods have been developed which allow virtually every product and/or process to be tested with regard to its electrostatic safety in explosive atmosphere. These methods are based on a charging process under worst case conditions and a subsequent investigation of the resulting provoked discharges either by incendive test gas mixtures or by pure electrical measuring methods. The methods were described and applied to products, processes and the clearing up of explosions which actually occurred within the past year.

K/W: Electrostatics, testing, products, processes, transferred charge, test gas, accidents

9p-2 One-dimensional Fluid Model for Charge Neutralization by Ionizers

Atsushi Ohsawa

National Institute of Industrial Safety

A one-dimensional fluid model for charge neutralization by ionizers has been developed. It consists of a model for ion sources, the continuity equations for positive and negative ions, Poisson's equation for the electric field and the circuit equation for obtaining the charge of an object to be neutralize. In this paper, the model is applied to an ac ionizer at the commercial frequency of 50 Hz without background airflow and the motion of ions and the charge decay of an object to be neutralized are investigated. The phenomena of neutralization are very different from those with airflow in the motion of ions as well as the decay time. The offset voltage is always positive because of the relatively higher mobility for positive ions than that for negative ions at low electric fields, and consequently a small positive space charge exists at the surface of the object. It was found that the total space charges created by the positive and negative ions are quasi-neutralized in the ion transport region at a steady state, while the charges has the oscillation by the discharge frequency in the vicinity of the ionizer, resulting in a small fluctuation in the offset voltage of the object.

K/W: fluid model, charge neutralization,Ac corona ionizer

Session 9 “Other topics”

9p-3 Charge Transfer of Spark Discharge between a Grounded Electrode and an Array of Charged Multiple Electrodes

Toshiyuki Sugimoto, Satoshi Ogata and Yoshio Higashiyama

Yamagata University

The charge transfer of electrostatic discharges occurring between a grounded sphere and an array of charged multiple electrodes were investigated experimentally for understanding basic properties of the air discharge occurring between a grounded object and space charges. Eight by eight array of rod electrodes was charged positively or negatively by the corona discharge. The estimated charge density of the array was up to 22 micro C/m3. The charge transfer of the discharge occurring between the array and a grounded sphere electrode approaching to the array were measured for various series resistor connected to the grounded sphere.

K/W: corona charging, spark discharge, space charge cloud, multiple electrode

9p-4 Use of Volatile Additives to Increase the Antimicrobial Efficacy of a Corona Discharge

Lindsey Gaunt and John Hughes

School of Electronics and Computer Science, University of Southampton

The antimicrobial effects of charged reactive ion species produced by cold plasma discharges are well recognized. Total sterilization can be achieved on media in close proximity to the plasma source (1). The aim of this research was to investigate whether the antimicrobial efficacy of a corona discharge could be improved by the use of antimicrobial volatile additives in the gas mixture of the discharge. Volatile compounds known to have good antimicrobial effects, such as ethyl alcohol, cinnamon oil and the essential oil of Melaleuca alternifolia (tea tree oil) were evaporated into the air around the ground electrode of a point-to-grid geometry corona discharge. Testing against Escherichia coli and Staphylococcus aureus in enclosed booths showed that the use of some antimicrobial volatile additives, such as ethyl alcohol and cinnamon oil, can significantly increase the bactericidal effects of a corona discharge. In the case of tea tree oil, however, the reaction with the ionic species produced in a corona discharge seems to lower the antimicrobial activity. Our results suggest that the use of some volatile additive can increase the antimicrobial effects of a corona discharge.

K/W: Non-thermal plasma, corona, bacteria, essential oil.

9p-5 Flow Electrification-Applications in Transformers

T. Paillat1, O. Moreau2 and G. Touchard1

1 Laboratoire d'Etudes Aerodynamipues (LEA), Bd Marie&Pierre Curie, 2 Electricite de France (EDF) R&D Service ERMEL

The phenomenon of flow electrification is first theoretically analyzed in the case of a conductive pipe. The physicochemical process leading to the phenomenon is investigated assuming the so called "corroding model". The space charge density evolution in the diffuse layer is then computed for a liquid at rest, then in the case of a laminar and a turbulent flow. The development of the diffuse layer at the entrance of the pipe and the charge convected in terms of the length of the pipe is also examined. The second part of the paper is devoted to the phenomenon observed in high power transformers. The flow geometry is first investigated, then a well representative of thephenomenon is compared to usually used parameters. Finally the influence of the pressboard composition is analyzed.

K/W: Flow electrification, Electrostatic Hazards, High power transformers.

9p-6 The Antibacterial Effects of Ionized Vapours Emitted from Candles

Sabrina Higgins, Lindsey Gaunt and John Hughes

School of Electronics and Computer Science, University of Southampton

It is known that ionized species such as those generated by a corona discharge can have bactericidal effects and that similar ionized species are emitted from the flame of a candle. Liquid contact tests have shown that certain volatile compounds have antimicrobial effects. This research aimed to explore the combined bactericidal effects of ionized species emitted from a candle flame and volatile compounds present within candle wax. The essential oils of orange, palmarosa, may chang and thyme as well as a constituent of tea tree oil; β–pinene, were incorporated into the molten candle mixture. These candles were tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), (gram negative and gram positive respectively), in an enclosed booth with a volume of 2.7m3. Results show that a candle containing any one of these volatiles has a greater antibacterial effect than a plain wax candle or the vapour from the volatiles alone.

K/W: Antibacterial, Essential oil, Ionized species, Candle, E. coli, S. aureus, β-pinene, Thyme, Orange, Palmarosa, May chang.

9p-7 "Elekiter"-Japan's First Electrical Machine-Restoration and Measuring Characteristics

Ryo Nishimura, Katsumi Nishimori and Naganori Ishihara

Electrical and Electronic Engineering, Tottori University

In 1770, Gennai Hiraga, a member of the Takamatsu clan born in Shidoura, Sanuki, Okawa-gun (a county of Kagawa Prefecture) was given a broken machine called “Elekiter”, which could generate static electricity by friction, belonging to a Dutch translator. He repaired the generator in 1776. The Elekiter is believed to be the oldest electrical machine created in Japan. In 1814, Tachu Kasamine described an inner structure and an example of the dimensions of the Elekiter. In this research, aiming to investigate the electric characteristics of an Elekiter at that time (the Edo era), we restored an Elekiter referring to Tachu’s discription without using synthetic resins. The Elekiter was restored by using wood, metals, Japanese paper, silica glass and Japanese lacquer. We measured the basic characteristics of the restored Elekiter. The Gennai’s Elekiter is now stored and on display in Hiraga Gennai Memorial Hall in Sanuki City (Kagawa prefecture), it is too old to generate electricity. We could also estimate the characteristics of the Gennai’s Elekiter using the characteristics of the restored one.

K/W: electrostatics, generator, Gennai Hiraga, electrical machine, Friction, Elekiter

Atmospheric Pressure Plasma Application (Special Symposium)

Session10 “Air Cleaning-VOC etc.”

10a-1 Atmosperic Pressure Non-Equilibrium Plasma Application for Environmental Protection

Tetsuji Oda and S. B. Han

School of Engineering, The University of Tokyo

Outline of atmospheric pressure non-equilibrium plasma is described and new topics on the process combined with catalysts (new type: manganese oxide) are explained where some experimental results are introduced. The new catalyst, manganese oxide, can decompose ozone well to generate atomic oxygen. The oxidation of the volatile organic compounds is strongly enhanced by that atomic oxygen. The minimum specific energy 85% decomposition efficiency but the carbon transfer efficiency from TCE to carbon oxide is not so good (only 50%)

K/W: plasma, environmental protection, catalyst, manganese oxide

10a-2 Influence of Ferroelectric Materials and Catalysts on the Performance of a Non-thermal Plasma (NTP) for the Removal of Air Pollutants

F. Holzer, U. Roland and F.-D. Kopinke

UFZ-Centre for Environmental Research Leipzig-Halle, Department of Environmental Technology

The introduction of ferroelectric and catalytically active materials into the discharge zone of NTP reactors is a promising way to improve the performance of NTP for the removal of hazardous substances, especially in case of low concentrations. In this study, different coaxial barrier-discharge plasma reactors varying in size and barrier material (glass, Al2O3 and TiO2) were used. The oxidation of MTBE, toluene and acetone was studied in a homogeneous gas-phase plasma reactor and in various packed-bed reactors (with ferroelectric and catalytically active materials). Both, better energy efficiency and CO2 selectivity were found for the oxidation of the model substances in the ferroelectric packed-bed reactors. Comparing experiments applying glass beads in the NTP reactor with a surface area comparable to the ferroelectric pellets did not show higher energy efficiency than the homogeneous gas-phase reactor implying that not surface processes or gas flow dynamics were the main reasons for the better performance. Instead, the changed characteristics of the electrical discharge caused by the ferroelectric pellets obviously results in an enhanced conversion of pollutants. Studies on the oxidation of a toluene/acetone mixture showed an enhanced oxidation of the less reactive acetone related to toluene in the ferroelectric packed-bed reactors. Hence, the change of the electrical discharge behaviour was caused by a larger number of non-selective and highly reactive plasma species formed within the ferroelectric bed. In case of combining ferroelectric (BaTiO3) and catalytically active materials (LaCoO3), only a layer-like realisation led to synergetic effects utilising both highly energetic species formed in the ferroelectric packed-bed and the potential for total oxidation provided by the catalytically active material in the second part of the packed-bed. The experimental results as a whole show that ferroelectric packed-beds alone cannot enhance the performance of an NTP sufficiently. Consequently, a combination with catalysis seems to be the method of choice for many applications.

K/W: micro-gap discharge, relative humidity, wire particle, corona onset, floating potential

10a-3 Low Temperature Decomposition of Aromatic Compounds Using Plasma-Driven Catalysis

Hyun-Ha Kim1, Jeong-Uk Park1,2, Kum-Chan Choi2, Atsushi Ogata1 and Shigeru Futamura1

1National Institute of Advanced Industrial Science and Technology, 2 Environmental Engineering, Dong-A University

Decomposition of various aromatic compounds (benzene, toluene, o-, m-, p-xylene, and styrene) has been investigated using plasma-driven catalyst (PDC) reactor, which combines nonthermal plasma and catalyst in a single-stage configuration. Decomposition of formic acid (not aromatic compound) was also investigated because it was the common intermediate for the decomposition of aromatic compounds. The catalyst used in the PDC reactor was silver-loaded TiO2 catalyst. The behavior of the PDC reactor for different VOCs was evaluated in terms of specific input energy, reaction rate constant, carbon balance, and COx (CO+CO2) selectivity. All the tested VOCs showed zero-order kinetics to the specific input energy with the PDC reactor.

K/W: non-thermal plasma, PDC(plasma-driven catalysis), VOCs, Aromatic compounds

10a-4 Characteristics of Parallel Type Streamer Corona Discharger for Deodorization and Decomposition of Gaseous Pollutions

Toshio Tanaka1, Kanji Motegi1, Kenkichi Kagawa1 and Toshikazu Ohkubo2

1Daikin Air-conditioning R&D Laboratory, Ltd. 2Department of Electrical and Electronic Engineering, Oita University

In recent years, the researches on decomposition technology of the bad smell and detrimental chemical substances in air using electric discharge plasma are done actively. Positive streamer coronas are very effective for the treatment of smell and volatile organic compounds. It is very important to get stable streamer coronas instead of glow coronas by optimizing electrode geometry. However, it is not easy to generate stable streamer corona in needle-to-plate electrode system. In this paper, the discharging characteristics of a parallel type streamer corona discharger were studied to optimize the geometric conditions for generation of streamer corona. As a result, optimum condition about electrode geometries was obtained. The discharger can generate stable streamer coronas for longer operation even if abrasion/ erosion of discharging electrode occurred.

K/W: DC streamer corona, paralel type electrode

Session 11 ”Flue Gas Process”

10a-5 Applications of Non-Thermal Plasmas to Combustion Enhancement

Louis A. Rosocha, Yongho Kim and Sy Stange

Plasma Physics Group, Los Alamos National Laboratory

As a primary objective, we are aiming to minimize U.S. energy dependency on foreign resources through experiments incorporating a plasma assisted combustion unit. Under this broad category, we specifically seek to increase efficiency and reduce NOx, CO, and unburned hydrocarbon emissions in internal-combustion engines, gas-turbine engines, and burners. To date, experiments on lean-burn operation with propane, consisting of higher air to fuel ratio, have successfully been carried out in a regime where reduced NOx /CO emissions are expected and have also shown increased combustion efficiency (less unburned hydrocarbon) and improved flame stability. By incorporating lean burn operation assisted by a non-thermal plasma (NTP) reactor, we hypothesize that fracturing of hydrocarbons and generation of active species from the plasma-fuel interaction can result in increased combustion efficiency and stability in a combustion system. We have shown that a silent electrical (dielectric-barrier) discharge - generated non-thermal plasma can be used to activate propane fuel, significantly enhancing combustion in an activated propane-air mixture, as determined by mass spectrometric measurements of combustion -effluent gas concentrations. The plasma energy density required to achieve such enhancement is modest, of order 100s J/std lit. Also, visual observations of activated propane-air flames indicate an increased spatial stability of the flame, increased blowout limits (leaner burn), and increased flame propagation speed. If applications to other fuels (e.g., gasoline, diesel, jet fuel) are successful, non-thermal plasma-assisted combustion may prove to be highly beneficial to the energy needs of modern society.

K/W:non-thermal plasma, combustion enhancement, plasma-assisted combustion, silent discharge, dielectric-barrier discharge.

10a-6 Simultaneous Removal of Nox and CO from Exhaust of Diesel Engine Power Generator by Plasma-Catalyst System

S. Iwasaki1,2, D. Brocile1, K.. Yamada1,3, K. Urashima1, M. Ara1, D. Ewing1, J. Hoard4, H. Ehara2, S. Ono2, T. Ito2, M. Itoh3 and J. S. Chang1

1Department of Engineering Physics, McMaster University, 2 Department of Electrical, Musashi Inst. Tech., 3 Dept. Chem. Eng. And Material Sci, Doshisha University, 4 Ford Motors Company

A preliminary experimental investigation has been conducted to study simultaneous removal of NOx and CO from exhaust of diesel engine power generator by hybrid reactor, consisting from magneto-trench barrier discharge and Na-Y catalyst. The experiments were conducted for the engine load from 0 to 2.4kW, exhaust gas flow rates from 2 to 5kg/h and applied voltages from 0 to 22kV at fixed magnetic field of 0.5kG. The soot particles contained in the exhaust were removed by an electrostatic precipitator placed upstream of the plasma-catalyst reactor. Results show that the part of NO was oxidized by plasma reactor simultaneously with NO removal. However, no significant CO oxidation (<5%) was observed since NaT catalyst was operated at low flue gas temperatures (31°C)

K/W: plasma-catalyst, NOx removal, diesel exhaust

10p-1 NOx Reduction System Using Nonthermal Plasma Desorption under Oxygen-poor Condition

Masaaki Okubo, Masaki Inoue, Tomoyuki Kuroki, and Toshiaki Yamamoto

Department of Energy Systems Engineering, Osaka Prefecture University

In the flue emission from internal combustion system using diffusing combustion such as coal or oil fuel boiler, incinerator or diesel engine, around 10% oxygen is usually included. It is difficult to reduce the NOx in the emission completely using catalysts or plasma alone because the part of NOx is oxidized under O2 rich environment. In order to overcome these difficulties, we proposed a new after treatment system of NOx included in exhaust gas of combustion system using nonthermal plasma (NTP) desorption and reduction. In this system, exchangeable adsorbent columns are equipped. First, the exhaust gas including NOx is adsorbed to a NOx adsorbent for a period of DTa. After the period of DTa, the path of exhaust gas is changed with a pair of rotary valves and NOx adsorbent is changed. The adsorbed NOx is desorbed from the adsorbent and reduced by applying NTP for a period of DTd using N2 or gas. The exhaust gas is always kept clean by the exchange of adsorbent. It is confirmed that the NOx complete reduction using N2 NTP desorption is possible not only for a simulated exhaust gas but for a real diesel engine gas. The effective or apparent SED can be decreased using this system. adsorption, desorption, reduction, Nox, exhaust gas, nonthermal plasma, plasma desorption, nitrogen nonthermal plasma, pulse high voltage, packed-bed

10p-2 Comparison of Pt-Al2O3 and Plasma Oxidation Techniques for Enhancing Selective Catalytic Reduction of Nitrogen Oxides Jae-Ou Chae, V. Demidouk and V. Ravi Mechanical Engineering, Inha University In the present work, a comparative study on the effect of pre treatment of the gas stream using two different oxidation techniques such as noble metal catalyst and electric discharge plasma prior to selective catalytic reduction of NOx is carried out. The experiments were carried out in a temperature range of 170°C-270°C using a simple gas composition consisting of NO, O2 and N2. Pt-Al2O3 was used as an oxidation catalyst and a dielectric barrier discharge reactor was used as a plasma reactor, both for the purpose of oxidizing NO to NO2. Performances of these techniques were compared on the basis of their contributions to increase in NOx removal efficiency on a SCR catalyst.

K/W: Plasma, Pt-Al2O3, Oxidation, SCR process, NOx removal

Session 12 “Other topics”

10p-3 An Effective Means for Corona Plasma Generation Utilizing a Dielectric Pellet Barrier and a Meshed-Plate

Jae-Duk Moon

School of Electronic and Electrical Engineering, Kyungpook National University

An increasing concern over environmental problems facing the world has stimulated interest in the study of new and more effective means of gas-cleaning technologies such as a nonthermal plasma reactor. In this paper, two new types of nonthermal discharge plasma reactors generating plasma effectively are presented. One is a point-to-mesh type nonthermal plasma reactor with a DC corona charged dielectric pellet barrier on the mesh. In this reactor, electric charges stored on the surfaces of the dielectric pellets by a corona discharge provide partial electric fields on the surfaces of the dielectric pellets, which can widen surface discharges on the dielectric pellet barrier. As a result, the output mean corona current and ozone concentration increase drastically. The other is a barrier type plasma reactor with a meshed-plate electrode instead of the conventional plate electrode. In this case of plasma reactor, a corona discharge can occur at the thin and sharp edges of the meshed-plate electrode, and the corona onset voltage of the airgap of the plasma reactor is greatly decreased. Additionally, the dense ozone produced in the high-temperature discharging airgap spacing can escape through the air-vacancies of the meshed-plate electrode into the low temperature region, and little decomposition of the produced ozone could be made.

K/W: Corona discharge plasma reactor, Ozone generation Point-mesh electrode, Dielectric pellet barrier, Meshed-plate electrode, Dielectric barrier.

10p-4 Laser Indeced Fluorescence Measurement Generated by a Pulse Barrier Discharge of Atomic Oxygen -Oxygen Concentration Effects-

Kei Takezawa1, Ryo Ono2 and Tetsuji Oda1

1University of Tokyo, 2National Institute of Advanced Indstrial Science and Technology

Laser Induced Fluorescence(LIF) measuring system was applied to ob-serve of atomic oxygen generated in a positive pulse barrier discharge under a high oxygen concentration condition as TALIF(TWO photon Absorption Laser Induced Fluorescence). The electrode conflguration was a metal needle to a plate electrode. That ground electrode was covered with a glass plate as the barrier. The concentration of the atomic oxygen and its reduction rate with

time, that vertical distribution were not directly related with background oxy-gen concentration. The reduction rate near the needle electrode was faster than that at any other position.

K/W: atomic oxygen, barrier discharge, two photon absorption LIF

10p-5 On Generation of DNA Molecular Beam and Plasma

Kazunori Tkashima, Jun Komatsu, Shinji Katsura and Akira Mizuno

Department of Ecological Engineering, Toyohashi University of Technology

Fundamental study on generation of DNA molecular beam and plasma were carried out in vacuum. To generate DNA molecular beam, a needle-plate electrode system was used. DNA molecule was set on the surface of the needle electrode, and high voltage was applied. Preliminary experimental result indicated that a different emission pattem was obtained when lambda DNA was placed on the tip, indicating possible emission of DNA molecules. Generation of DNA plasma was also studied in low pressure glow discharge aiming at inducing chemical reactions for biological molecules in gas phase or vacuum. DNA molecules were introduced into the plasma by sublimating liquid nitrogen cooled ~ phage DNA solution in vacuum in the presence of electric field. Fluorescent microscopic observation of a glass substrate exposed to the DNA molecular plasma detected no apparent images that could be identified as DNA molecules. Recovered substances on a glass substrate were analyzed by gel electrophoresis after PCR amplification resulting in no specific products. These results suggested that DNA molecules were not recovered on a glass substrate or that they were recovered but not detected because of serious fragnentation.

K/W: DNA, sublimation, deposition, field