Abstract of papers presented at 33rd Annual Meeting of IEJ (2009)


Reconstruction of 3-dimensional structure of streamer discharges

Ryuta ICHIKI*, Seiji KANAZAWA*, Shuichi AKAMINE*, Toshikazu OHKUBO*, Marek KOCIK**, and Jerzy MIZERACZYK**
*Oita University, **Polish Academy of Science
For reconstructing 3D structures of streamer discharges we propose a new stereographical method, where streamers are observed from three directions simultaneously. The three-directional observation enabled to obtain fine positional coordinates of streamers for a relatively large area, without losing the possibility of identifying each streamer channel readily. This method can estimate streamer characteristics such as branching angle and propagating velocity.


The effect of the catalyst material on the electrical characteristics of the DBD reactor

Akira Mizuno, Mazen Abdel-Salam, Adel Ahmed
Toyohashi University of Technology
This paper is aimed at investigating the role of the different catalysts in improving the energy efficiency of the dielectric barrier discharge (DBD). The electrical characteristics of DBD reactor with/without catalysts such as, ?alumina and glass pellets were measured using Lissajous figures. From the Lissajous figures, the transferred charge and power consumed during a complete cycle were determined to select the best catalyst for DBD reactor to obtain the highest energy efficiency. The voltage and electric field distributions of the DBD reactor without catalysts at any instantaneous voltage using ANSYS simulation package were examined.


Measurement of emission spectrum in hydrogen-oxygen ignited by spark discharge

Ayumi KUMAMOTO*, Ryo ONO* and Tetsuji ODA**
*Graduate School of Frontier Sciences, The University of Tokyo,**School of Engineering, The University of Tokyo
We have observed the ignition mechanism of hydrogen-air mixture gas ignited by the electrostatic discharge (ESD) for to prevent the hydrogen explosion hazard from occurring. In this experiment, we measure the emission spectrum in hydrogen-air mixture ignited by spark discharge. We measure the spectrum in the ratio of hydrogen to air is three to seven, and we use the needle electrode under the discharging gap is 1 mm.


Emission Spectroscopy of Microplasma Using a Pulsed Power Supply

Marius BLAJAN, Shuichi MURAMATSU, Tatsuya ISHII,Hidenori MIMURA, Kazuo SHIMIZU
Shizuoka University
Emission spectrum of the microplasma discharge in N2 or air with water droplets was analyzed. Two experimental Marx Generators were used as pulsed power supplies, with negative and positive pulse respectively. Emission spectra for N2 gas with water droplets show N2 second positive band system (N2 SPS), N2 first negative band system (N2 FNS), H-γ band system, and OH peaks. For air with water droplets emission spectrum shows N2 SPS, N2 FNS and H-γ band system with lower intensities comparing with microplasma discharge in N2 gas with water droplets. Emission signal of the photomultiplier, show short lifetime emission signal for N2 SPS of 337.1 nm. Temperature measurements are also carried out, which show the temperatures are specific for non-equilibrium plasmas.


Interaction of Discharge Plasma with Nanoparticle Metal Catalyst Supported on Zeolites

Hyun-Ha Kim*, and Atsushi Ogata*
National Institute of Advanced Industrial Science and Technology (AIST)
In this work, physical and chemical roles of metal nanoparticles (Ag, Zr, Cu) supported on various zeolites are investigated to understand the interaction of atmospheric pressure nonthermal plasma and catalyst. The physical role of metal nanoparticles on the generation of discharge plasma on zeolites was visualized using the optical observation system, consisting of a microscope?ICCD camera. It was found that the metal nanoparticles supported on zeolites assisted the discharge plasma to expand over a wide surface area. Among the tested active metals in this study, silver exhibited the most prominent influence in the generation of discharge plasmas on the surface of zeolites. On the other hand, plasma generation was limited to the edges of the zeolites when the bare zeolites were used. The difference in the shape and the area of the discharge plasma was also found to be correlated with the performance of plasma?catalyst reactor for the decomposition of volatile organic compou! nds.


Laser-induced Fluorescence Measurement of Time Evolution of OH Radicals in Atmospheric Pressure Pulsed Corona Discharge

Yusuke Nakagawa, Ryo Ono and Tetsuji Oda
School of Engineering, The University of Tokyo
The time evolution of relative density of OH radicals is measured in pulsed positive corona discharge under atmospheric pressure using Laser-induced Fluorescence (LIF) method. The OPO laser stabilized to 281.916nm corresponding to the excitation from X 2Π(v=0) state to A 2Σ (v=1) state is used, and then the fluorescence from A 2Σ (v=1) to X 2Π(v=1) is detected. The discharge occurs within a series of 15 mm needle to plane gap in humid air. Taking into account that the LIF signal is proportional to laser power under 1.2mJ, we checked that the influence of dissociation of ozone to excited O radical by the laser beam and the production of OH by O radical are negligible.


LIF Detection of OH Radicals Produced by a Discharge over Water Surface

Seiji Kanazawa*, Michihiko Hirao*, Shuichi Akamine*, Ryuta Ichiki*, Toshikazu OHKUBO*,Marek Kocik**, Jerzy Mizeraczyk**
* Department of Electrical and Electronic Engineering, Oita University ** Institute of Fluid Flow Machinery, Polish Academy of Sciences
A possibility of LIF measurements for pulsed discharges over a water surface was investigated. A nozzle-to-plate electrode system was used, where the tip of the nozzle was attached onto the water surface and plate electrode was immersed in water. Pulsed discharge with positive polarity was generated and fine structures of the streamers such as propagation characteristics and branching patterns were measured by an ICCD camera. Two-dimensional distribution of the ground-state hydroxyl (OH) radicals was successfully observed by a single-shot LIF. It was found that OH radicals stayed mainly in the region of the streamer propagation and the OH-LIF intensities decreased gradually with time after the discharge pulse.


Measurement of Nitrogen Atoms in Atmospheric Pressure Pulsed Corona Discharge Using TALIF

Yoshiyuki Teramoto, Ryo Ono, and Tetsuji Oda
School of Engineering, The University of Tokyo
Spatial distribution and temporal profile of atomic nitrogen are measured in N2 pulsed positive corona discharge using time-resolved, two-photon absorption laser-induced fluorescence (TALIF) under atmospheric pressure. Ground state N (2p3) 4S3/2 is excited to (3p) 4S3/2, then fluorescence from (3p) 4S3/2 to (3s) 4P1/2, 3/2, 5/2 is detected. From measurement of decay of nitrogen atoms in pure nitrogen gas, nitrogen atoms mainly decrease by three-body reaction which is recombination reaction, N + N + M → N2 + M. When the discharge voltage is 21.5 kV, the nitrogen atom density near the anode tip is estimated to be about 2.4×1016 cm-3 using the decay rate of recombination reaction.


Development of EHD ESP for Collection of Low Resistive Diesel Particles

Yoshikazu Itou, Yoshiyasu Ehara, Toshiaki Yamamoto
Tokyo City University
The collection of low resistive particulate matter (PM) from diesel engine emission is extremely difficult by the conventional electrostatic precipitators (ESPs) due to particle reentrainment. The main reason is the particledetachment force due to induction charge is dominated over particle adhesion force. The new electrohydrodynamically assisted ESP (EHD ESP) was developed to minimize the reentrainment. The EHD ESP utilizes theionic wind to transport the zero electric field or the pocket attached to the collection plate, where electrostatic repulsion force acting on particles is zero, so that no reentrainment takes place. In the present study, particle size dependent collection efficiency was obtained using Scanning Mobility Particle Sizer(SMPS )and Particle Counter(PC)in the range of 20-5,000 nm and the performance of EHD ESP was evaluated. The EHDESP was extremely effective for suppression of particle reentrainment in comparison with the conventional ESPs and collection efficiency was insensitive for gas flow velocity.


Direct collection of high concentration Diesel Exhaust Particle of ESP

Ryousuke NAKANO、Toshiaki YAMAMOTO、Yoshiyasu EHARA、Yoshihiro KOUNO、Akinori ZUKERAN
Tokyo City University
An environmental problem is concerned about on a global scale, and air pollution by DEP (diesel disposal fine particles) or the NOx becomes the serious problem now. There are the movement outbreak sources such as a car or the ship as the outbreak source of the main toxic substance. Severe regulation approaches in the post-newly long-term regulation (2009) of the diesel car. In addition, an MARPOL treaty was adopted in 1997, and effluent control of the air pollution material from a ship has been begun a full-scale. Effluent gas disposal of various diesel engines is an urgent problem. In this study, I am aimed at removing the discharge particle from a diesel engine with an electrostatic precipitator (ESP) directly.


Pilot-Scale Boiler NOx Control using Indirect Plasma and Chemical Hybrid Process (Effect of Packing Material Height on NOx removal)

Hidekatsu FUJISHIMA*, Atsuyoshi TATSUMI*, Tomoyuki KUROKI*, Atsushi TANAKA**, Keiichi OTSUKA**, Toshiaki YAMAMOTO****, and Masaaki OKUBO*
Osaka Prefecture University,**Takao Iron Works Co., Ltd.,***Tokyo City University
A pilot-scale NOx removal from a small size boiler emission of city gas and heavy oil fuels was performed using indirect plasma and a chemical hybrid process. The flue gas flow rate was in the range of 455~1,440 m3N/h, and NOx concentrations of approximately 40 ppm in city gas firing and 100 ppm in heavy oil firing. The correlation between NOx removal efficiency and packing material height was investigated in order to obtain design criteria of the scrubber, varying the height from 2.1 m to 0 m. The packing height was required more than 0.75 m to achieve 70% of NOx removal efficiency for city gas fuel, and 60% of NOx removal efficiency for heavy oil fuel.


Continuous Operation of Pilot Scale Boiler NOx Control using Indirect Plasma and Chemical Hybrid Process

Yusuke YOSHIOKA*、Hidekatsu FUJISHIMA*、Tomoyuki KUROKI*、Atsushi TANAKA**、Toshiaki YAMAMOTO***、and Masaaki OKUBO*
Osaka Prefecture University,**Takao Iron Works Co., Ltd.,***Tokyo City University
Continuous operation tests of a pilot-scale NOx removal from a small size boiler emission of city gas and heavy oil fuels was performed using indirect plasma and a chemical hybrid process. The flue gas flow rate was 470 m3N/h in city gas firing and 735 m3N/h in heavy oil firing, and NOx concentrations of approximately 40 ppm in city gas firing and 90 ppm in heavy oil firing. It was achieved approximately 90% of NOx removal efficiency for city gas fuel, and 70% of NOx removal efficiency for heavy oil fuel.


Nano-particles Collection Using an Electrostatic Spray

Hisashi AYUZAWA, Harano AZUCHI
Dept. Chem. And Environ. Engineering Faculty of Engineering, Gunma University
Diesel engines release a large number of nano-particles into the atmosphere. Epidemiological, human and in vivo studies have demonstrated an association between PM from Diesel engines and various adverse health outcomes such as asthma and lung cancer. Most of today's filter-based technologies experience high operational back-pressures causing the buildup of soot deposits. The key to the acceptability of filters for diesel exhausts is the ability of the filter to be regenerated, or cleared of trapped particles, such that the exhaust back pressure remains low. The purpose of this study is to apply the electrostatic spray, that can substitute for the filter technologies, for collecting nano-particles. A differential mobility analyzer (DMA) is used to measure the distribution of nano-particles in order to investigate the collection efficiency of electrostatic spray method. And droplets size distributions produced by electrostatic spray were measured by a laser diffraction scattering analyzer (LDSA). From experimental results, it can be considered that there is no effect of the applied voltage to electrostatic spray on collection efficiency but the flow rate of water led to higher particle collection efficiency.


Practical NOx Removal Processes using Adsorption/Desorption and Nitrogen Plasma

Soma Asada, Hiroshi Aoki, Yoshiyasu Ehara, Toshiaki Yamamoto
Tokyo City University
Extremely cost effective NOx removal system was developed using the adsorption and desorption, followed by nitrogen plasma. The adsorbent was able to absorb 100-300ppm NO for a long time and desorbed with the external heat to achieve as high as 4,000ppm concentrated NO. More than 95% NO reduction was easily achieved using a series of 6 and 12 surface discharge units. The surface discharge plasma reactor was insensitive with gas flow velocity and concentrations. Therefore, the energy efficiency was optimized to incorporate with high flow rate and high concentration. The best energy efficiency obtained was 68.8g/kWh, which is approximately 1/5 the conventional SCR cost. This adsorption/desorption combined plasma process leads towards more economical and practical NOx removal system.


Experimental analysis of products of ozone injection to diesel exhaust gas

Kazuki KAWAHARA, Hiroshi UMEMOTO, Hirofumi KURITA, Kazunori TAKASHIMA and Akira MIZUNO
Toyohashi University of Technology
Particle matter (PM) can be removed from the diesel exhaust gas, by using a diesel particulate filter (DPF). Removed particles from the gas can be oxidized at 600℃. However, heat stress occasionally breaks DPF, therefore oxidation with at lower temperature is preferable. We found that ozone can oxidize carbon particles at 200℃. At room temperature, the number density of PM smaller than 30nm in diameter was decreased. However, at the same time the number density of PM ranging from 30nm to 200nm in diameter was increased. The purpose of this study is to clarify the mechanism of the oxidation and the products of ozone injection to diesel exhaust gas.With the ozone injection at 200℃, the number density of PM was increased and the concentration of gas component such as soluble organic fraction (SOF) was decreased after ozone injection 200℃. These PM was sampled using quartz filters. From the SEM observation, the increased PM were not carbon soot.These results suggests that the reaction of volatile compounds such as SOF with ozone formed PM.


NOx processing in diesel engine exhaust gas by packed bed electrical discharge

Yasuhiro Takasaki,Satoshi Sato,Hirofumi Kurita, Kazunori Takashima,Akira Mizuno Department of Ecological Engineering Toyohashi University of Technology
As for diesel engine, thermal efficiency is higher than the gasoline engines, and the emission of CO_2 is smaller. However, because of higher NOx and a PM emission, the influence on the air environment is feared. The postprocessing technology is needed to meet exhaust emission regulations in the future, and Selective Catalytic Reduction (SCR) using urea etc. as a reducing agent is now studied. Urea SCR has the problem that the activity of the catalyst ecreases in low temperatures. In the present study, the method of removing NOx by using SCR catalyst together with packed bed electrical discharge plasma at low temperature was examined. By assisting in SCR catalyst by plasma, NOx in the diesel exhaust was able to be decreased by about 45% at 100℃. The number of particles decreased by the ammonia addition and the electrical discharge from the result of EEPS measurement.* ***


Effects of NH3 on the particle formation from SO2 by corona discharge

Kenkichi Nagato, Yuya Nonaka, Shinji Maeda
Kochi National College of Technology
In order to study the effects of NH3 on the particles formation from SO2 in discharge plasmas, mobility distributions of the particles generated by positive dc corona in NH3/SO2/H2O/Air mixtures have been measured using DMA. The enhancements of nucleation by the addition of NH3 were observed, and the mobility distribution of the particles shifted to the lower mobility region with increasing NH3 concentration. The distribution consisted of a few peaks, suggesting that the particles became larger sizes through several growing steps.


Charged Particle Generation Characteristic of Corona Discharge Ionizer in Air or N2 Atmosphere

Yudi Kristanto, Masaki YOSHIOKA, Kazuo OKANO
The Polytechnic University
To use corona discharge ionizer to eliminate static charge in the manufacturing of organic electro-luminescence, that mostly held in N2 atmosphere, we need to investigate the charged particle generation characteristic of corona discharge ionizer in air or N2 atmosphere. The characteristic was investigated by measuring I-V characteristic and wave forms of current based on charge particle generated by ionizer in air or N2 atmosphere. Current based on negative charged particle in N2 atmosphere is higher than current based on positive charged particle in N2 atmosphere and current based on charged particle in air.


Improvement of the Characteristics of a Corona Discharging Type Ionizer (Ⅱ)

M.Hattri*, D.Endo*, Y.Tanaka*, M.Yasuda*, J.Sugaya*, T.Saito**, K.Izumi**
* Sendai National College of Technology, ** Shishido Electrostatic, Ltd.
In our previous paper, we have investigated the performance of a piezoelectric transformer type ionizer which has a negative feedback gate circuit, and have reported that its eliminating time (decreasing time of 1kV to 100V of a plate monitor) and the generating density of ozone gas depend on the gate circuit frequency and duty ratio parameters. In this paper, we investigated the influence of the amplitude of an applied voltage to discharging needle mainly, and tried to measure an instantaneous waveform of discharging needle current. As a result, it is clear that discharging current contains a great deal of space capacitor current (displacement current) compared with pure ion current, therefore some methods of compensating such a big current are necessary to analyze the mechanism of an effect of the gate frequency. Moreover, a DC power supply type ionizer was tested and compared with the characteristics of the piezoelectric type one.


Development of ion-conveying-type ionization system generating large charged-particles by ionic nucleation of water vapor part3

Masanori SUZUKI*, Takashi MATSUDA*, Hideaki MATSUHASHI* and Akira MIZUNO**
*Technical R&D Center, Techno Ryowa Ltd., ** Dept. of Ecological Engineering, Toyohashi University of Technology
In order to control static electricity in narrow space such as space in ULSI and LCD manufacturing equipments, we have conducted the development of low energy X-ray ionization system that conveys ions through tubes. However, it was serious problems that the amount of positive and negative ions decreases rapidly in a tube by electrostatic diffusion or recombination. In this paper, we will report the results of investigation on the influence of the air inlet position at the generating chamber of charged-particle, how to supply purge air and so forth, for optimizing charge eliminating performance of the new ionization system generating large charged-particles by condensing water vapor with the vortex-tube.


An Estimation for Relaxation Characteristics of a DC Ionizer Ion Cloud Density Transferred through a Pipe via Hyperbolic Law

Takashi Yasukawa、Yatsuzuka Kyoko
Koganei Corporation
Corona discharge is widely used to eliminate the electrostatic charge. The ions generated by DC or AC discharge are often carried through a pipe or a tube toward the vicinity of the object. It is well known that the ion density decreases with the traveling distance, however, the details of the mechanism is not clarified yet, because of the difficulty of the measurement for the charge relaxation process. We have investigated and reported about the measurement of the transferred ion density by a Faraday cage directly connected to an ionizer. In this report the experimental results of the relaxation characteristics of ion density transferred through a pipe between the ionizer and the Faraday cage by changing its length. The discharge current decreases with the traveling distance because of the inside air pressure increasing in the ionizer. The dependency of the ion current on the pipe length shows very good agreement with the estimation via hyperbolic law. The ion velocity and mobility take place very important roles in the hyperbolic law.


Characteristics of a dc ionizer applied in the vivinity of the target.

Yoshihisa Shirai、Toshiyuki Sugimoto
Graduate School of Science and Engineering,Yamagata University
Characteristics and modeling of a non-airflow dc ionizer have been investigated to predict the performance of the ionizer applied in the vicinity of the target. The ionizer was composed of positive and negative high voltage needle electrodes and a grounded mesh electrode. Potential decay time of charged plate target was measured for different distance between the ionizer and the target. The charge decay model to predict the performance of the ionizer was presented.


Development of Explosion-Protected General Electrostatic Neutralizer

Tomofumi MOGAMI*, Kwang Seok CHOI **, Mizuki Yamaguma **, Teruo SUZUKI ***, Takashi IKEHATA***
*Ibaraki University , **National Institute of Occupational Safety and Health, ***Kasuga Denki INC
The explosion-protected electrostatic neutralizer has been developing, which can be used to reduce effectively the static charges on flammable material in general industries. For the purpose of IEC standard, the punched plate was inserted to opening area of nozzle of neutralizer. The punched plate as an enclosure provides protection of equipment against the ingress of solid foreign objects. The current study investigates the influence of punched plate on performance of neutralizer. Several kinds of punched plate were used in this study. The ion current, Ie [A] was measured with an ammeter connected between the charged metal plate impressed with both high voltage, Vp [kV] (DC 5 kV in bipolar) and the ground. The air pressure of the airflow was maintained in 0.1 MPa. As the results, Ie decreased as distance, a [mm] between discharge electrode and punched plate increased. The performance of neutralizer depended strongly on size, number, and thickness of punched plate.


examination of Electrification Series, Cohen’s Law, and ESD

Norio Murasaki
Tokyo University of Agriculture and Technology
Electrostatics shall be supported for the future by 4 items as below. (1)Triboelectric series in the stable condition must be recorded together with order change in physical or chemical stress. (2)Cohen’s law is crude but right. (3)It is possible to see 5 methods of charge generation, in which mechanical, electrical, optical, thermal, or chemical energy is changed to static energy by a effect of material. (4)ESD is not discharge in 3 dimensional uniform typical field, and surface leakage is not current in 2 dimensional uniform typical field.


Effect of External Electric Field on Triboelectric Series of Polymers

Free Lance Scientist
The effect of external electric field on the polarity of triboelectric charge on insulating polymers was studied for examining whether the intensity of the external field for reversing the polarity is related to the triboelectric series of the polymers. The experimental results showed that the location in the triboelectric series determined the intensity, though the mechanism of reversing the polarity has not been clarified yet.


Charging Property and Charge Trap Parameters in Porous Polypropylene Film using Thermally Stimulated Current

Fukuzo YOSHIDA and Masahiko YOSHIURA
Osaka Institute of Technology
Charge trap parameters and charging property of porous and solid polypropylene (PP) films were studied using TSC. From the evaluation of TSC by means of the Asymptotic Estimation Method (AEM), it was found that charge traps in PP films were reformed by drawing and holes. A comparison of surface potential decay revealed that drawing treatment caused discharge property by heating and the porous structure in the PP film induced charge storage stability.


Development of portable electrostatic distribution visualization system

Hiroshi ONOMAE
Kagoshima Prefectural Institute of Industrial Technology
The electrostatic distribution visualization system by scanning the measured surface with the electrostatic voltmeter was developed. It can visualize the electrostatic distribution of measured surface in high resolution with a high-resolution evaluation electrostatic voltmeter and a precise XYZ stage and a digital microscope. The result of this system was almost the same as earlier methods (Electrification powder scatter method). In addition, this system also has the following advantage. - The voltage value of each part is understood. - Measured surface is not polluted.It became possible to verify a confirmation of the effect of the ionizer that existed in the manufacturing premise and best use by a portable visualization system.


Surface modification of polyimide film using atmospheric pressure microwave plasma

Masahito YAMADA Shigeru ONO
Tokyo City University
Surface modification experiment of polyimide film has been conducted using microwave excited atmospheric pressure Ar-O2 and Ar-H2O mixture gas plasma. Water contact angle and XPS were used as the measure of surface modification of polyimide film. Before plasma treatment, the value of water contact angle showed 69.5 degrees. As for Ar-H2O plasma and Ar-O2 plasma, contact angle of 24.4 degrees and 37.5 degrees was obtained, respectively. As a result, Ar-H2O plasma is useful to hydrophilic property grant on surface of polyimide.


Electrical Breakdown Voltages between Electrodes with Micro Separation on Insulating Surface

Yoshiaki Yamano
Faculty of Education, Chiba University
Electrical breakdown voltages on an insulating surface between knife edged electrodes separating with a micrometer gap were studied in air. The gap distances ranged from 0.5μm to 20μm, which was controlled by the piezo-actuator with a step of 20nm. It was experimentally found out that the breakdown voltages are independent of the gap distance when the distance is shorter than 5μm. In the case of the distance longer than 5〓m, the breakdown voltages increase with the gap distance, and the voltage at 20μm of the distance is almost on the modified Paschen curve. The conductive current increases up to a few 100pA or more at the voltage 5% lower than the breakdown. This indicates that the breakdowns in the shorter gap distance area are significantly induced by the current due to the electrical field emission from the edge of cathode.


Electrical Tree Propagation in LDPE Nanocomposite with Surface Coated Nano-Particles

Yoshiaki Yamano and Kouki Imai
Faculty of Education, Chiba University
Tree initiation voltages (TIVs) and tree propagation rates (TPRs) for LDPE nano-composites were investigated by ac voltage application. The LDPE composites contained Al2O3 nano-particles coated with phthalocyanine compound or azobenzene (Az). The phthalocianine compounds used were tetra-t-butylphthalocyanito)Cu(II) (Tb-Pc) and nickelphthalocyanine (Ni-Pc). Concentrations of the particle and the coating agents in LDPE are 5wt% and 2wt%, respectively. LDPE blocks with the coated nano-particle were prepared in our laboratory by the solution casting method using toluene. The experimental results show that TIVs for LDPE with the coated nano-particle are higher than those for LDPE with the particle of non-coating. Az is the most effective agent to increase TIV, and the second is Tb-Pc, both of which are soluble in toluene. These two agents for the coating are also effective to control TPR. TPR for samples with Az coated particle is almost five times lower than that for samples without particle. In the case of Ni-Pc agent, the results indicate that the aggregation of the nano-particles in the LDPE with Ni-Pc prevents the control of tree propagation.


Piezoelectricity of Ferroelectret Thin Film

Yusuke ODA, Yasuhiro UENAKA, Shingo KATAOKA, Masatoshi NAKAYAMA, Ken YAMAMOTO and Yoshiro TAJITSU
Electrical Engineering Department, Graduate School of Engineering, Kansai University
Recently, the study of ferroelectrets with the piezoelectric constant d33 larger than that of lead zirconate titanate (PZT) ceramics has progressed rapidly. We fabricated a ferroelectret porous polyethylene (Fp-PE) film; its perpendicular piezoelectric constant d33 was 80 pC/N. In the Fp-PE film observed by atomic force microscopy (AFM), pores with a diameter of about 0.5 m were almost homogeneously distributed. Moreover, from piezoresponse force microscopy (PFM), it was found that areas surrounding the pores shift in one direction following the application of ac voltage, but that areas far from the pores cannot move freely. These results indicate that the electrical charges trapped in areas surrounding the pores in the Fp-PE film play an important role in piezoelectricity.


Destruction of Bacillus atrophaeus spores using atmospheric cold plasma

Yasuaki TANINO, Hirohumi KURITA, Hachiro YASUDA, Kazunori TAKASHIMA and Akira MIZUNO
Department of Ecological Engineering, Toyohashi University of Technology
We have developed a method of decontamination using dielectric-barrier discharge(DBD) which has advantages of low temperature operation, time-saving and non-toxicity over the conventional methods, such as dry heat, steam autoclave, γ-ray irradiation and ethylene oxide gas. Bacillus atrophaeus spore cells were observed with SEM in the course of the DBD treatment.


Sterilization Mechanism by a Steam Plasma Flow at Atmospheric Pressure

Takehiko SATO, Takeshi FURUI
Tohoku University
The reactive flow field and the sterilization mechanism by a steam plasma flow at atmospheric pressure were clarified to develop a plasma autoclave by experimental and computational methods. The OH radical finally changed to H2O1 in the condensed water si


Sterilization of E.coli by small size argon plasma jet

Daiki Shibahara,Hachiro Yasuda,Naoto Fujii,Hirohumi Kurita,Kazunori Takashima,Akira Mizuno
Toyohashi University of Technology
Non-thermal atmospheric pressure plasmas have recently been applied in the biomedical field. Gas discharge in plasma jet show a considerable promise for medical application where surfaces are exposed to plasma in a non-contact and site-specific manner at nearly the same temperature as the ambient gas. We have characterized a device of argon plasma jet of relatively small dimensions using smoke wire methods and optical emission spectrometry. Efficacy of decontamination by the plasma for the wet state of Escherichia coli cells was investigated in the several culturing conditions such as surface of an agar plate, inside the soft agar layer and in the water solution. Denaturation of the proteins inside the cell was also demonstrated.These results suggest that reactive species are produced from these water and they kill the bacterial cells.


Tissue and cell activation using micro-spot atmospheric pressure plasma source

Takamichi HIRATA*,***, Chihiro TSUTSUI***, Yukiko YOKOI*, Yuichiro SAKATANI*,Akira MORI*, Atsushi HORII**, Toshiaki YAMAMOTO**, Akira TAGUCHI*,***
*Department of Biomedical Engineering, **Department of Electrical and Electronic Engineering,***Nano Carbon Bio Device Research Center, Tokyo City University
For the diversified plasma applications to biomedical engineering, we carried out the experiments about the direct ion/radical irradiation to the tissue and cell using micro-spot atmospheric pressures plasma source. When cells were irradiated with the plasma, generated from glass capillary tip, the stromatolysis due to surface interaction such as collision or ionization of gas molecules was hardly observed in the preliminary experiment. Furthermore, it seems that skin damage of small animals (mainly rats) was not observed.


Gene transfer to E. coli by Plasma torch treatment

Hachiro YASUDA, Yoshimasa Tanaka, Naoto FUJII, Hirofumi Kurita, Kazunori TAKASIMA and Akira MIZUNO
Toyohashi University of Technology
Recently, study on application of plasma torches to the biomedical field has been expanding. We have reported the preliminary results about DNA transfection in E.coli cells using a plasma torch. In this report, we describe the experiments to improve the efficiency of the transfection. It was effective to shift the timing of the DNA addition to after exposure of the cells to the torch. The cause of the improvement for the transfection efficiency is discussed.


The sterilization of E.coli by the pulsed plasma generated in air spraying water droplets for applying to the treatment of waste water with disease germ

Atsushi ISHIKAWA, Taichi SUGAI, Tsukasa SAITO and Yasushi MINAMITANI Graduate school of Science and Technology, Yamagata University
Since the medical waste water discharging from medical institutions has to treat themselves by low, an efficient sterilization method is required. This work focuses the treatment of waste water with disease germs discharging from medical institutions. The sterilization of E.coli by pulsed discharge in air spraying water droplets was investigated. The number of sterilized E.coli did not have much difference for repetition rate of pulsed discharge. As a result , the low repetition rate has high efficiency for the sterilization of E.coli. The differences of the repetition rate and charging voltage at the same charging energy did not affect the number of sterilized E.coli.


Basic study of inactivation of bacteria at low discharge voltage by using Microplasma(Ⅲ)

Yuuki Komuro, Masahiro Yamada, Marius Blajan, Tsukasa Sugiyama, Kazuo Shimizu
Shizuoka University
Inactivation of micro-organism, such as Escherichia coli, was experimentally investigated by using microplasma. Microplasma is suitable for practical application for sterilization, since its discharge voltage is low and its apparatus could be small and inexpensive.In this study, Gram-negative Escherichia coli HB101 and Gram-positive Bacillus subtilis JCB20036 were used as the target to be sterilized.From the series of experiments, decrease in the amount of germs was effectively obtained after microplasma treatment. The effect of inactivation by microplasma was confirmed by a staining kit and a fluorescence microscope. A Scanning Effect Microscope was also used to observe the shape of bacteria before and after the microplasma treatment.


Prepared fine needle sample for field ion microscopy to DNA sequencing

Kei KAKUTA, Hachiro YASUDA, Kazunori TAKASHIMA and Akira MIZUNO
Toyohashi University of Technology
Field ion microscope (FIM) is a tool for direct observation of atomic structure at a tip of needle electrode. Fine radius of curvature is required to obtain the images with high resolution. An electro-chemical method has been used to prepare the fine needle tip. Using an ac voltage, a tungsten fine tip was prepared in alkaline solution. It was confirmed that the current associated with the electrolysis was an indicator for the process, and reproducible preparation could be made. With the needle prepared in this way, fine atomic images could be obtained. By Attaching DNA molecules on the needle, the sample for DNA sequencing by FIM was prepared.


Relationship between dielectric characteristic by DEP levitation and differentiation activity for rat mesenchymal stem cell

Yusuke Hirota , Masaru Hakoda
Gunma University
Stem cells are very useful undifferentiated cell with the differentiation ability which can differentiate into various tissues. As for the general method of analyzing the differentiation activity of the stem cell, it takes a lot of time, and the reagent and the equipment used for the measurement are expensive. Consequently, the dielectric characteristics (Re[K(ω)]) of the stem cells were measured using the DEP levitation and the relationship between the dielectric characteristic and the differentiation activity was examined. As a result, it was obtained the passage number (PN) of RMSC (Rat Mesenchymal Stem Cell) was increased with decreasing Re[K(ω)]. Moreover, the growth rate of PN2 and PN10 was measured. However, there was no difference in the growth rate by PN. The frequency dependency of Re[K(ω)] did not depend on the culture days. Moreover, bone differentiation induction was performed to the RMSC of each passage number, and the ALP activity was measured. As a result, the ALP activity was decreased with increasing passage number. Therefore, it was clarified that the correlation of the Re[K(ω)] and the ALP activity in the stem cell.


Gene transfer method using dielectric barrier discharge

Takuya MIURA, Hachiro YASUDA, Tomoko NAKAJIMA, Yoshimasa TANAKA, Hirofumi KURITA, Kazunori TAKASHIMA and Akira MIZUNO
Department of Ecological Engineering, Toyohashi University of Technology
Recently, atmospheric discharge plasma attracts attention and research on the application of the discharge has been expanding. Non-thermal plasma has advantages such as low thermal stress, steady processing and high chemical activity. Non-thermal plasma is also effective for sterilization. Through holes are observed when E.coli cells are exposed to atmospheric barrier discharge. In this report, we propose a novel gene transfer method using dielectric barrier discharge. The gene transfer experiment to E.coli cells was conducted. The gene transfer was confirmed by the following biological methods staining of colonies by X-gal, agarose gel electrophoresis of the DNA and DNA-DNA hybridization. It was shown that the gene transfer using dielectric barrier discharge was possible. It was suggested that the gene transfer using dielectric barrier discharge depended on discharge conditions, states of E. coli and chemical composition of the discharged samples.


Measurement of Dielectrophoretic Velocity for Bacteria in Microchannel

Satoshi Uchida, Humiyoshi Tochikubo
Tokyo Metropolitan University
Selective manipulation and separation of microparticles using dielectrophoresis (DEP) are useful for advanced bioengineering. However, understanding of the dielectric characteristics of bioparticles is essential for further development of these technology.


Corona discharge processing of dye-sensitized solar cell under atmospheric pressure

Taku SHIONO*, Yoshiyuki TERAMOTO**, Ryo ONO** and Tetsuji ODA
School of Engineering, The University of Tokyo
The world keeps an eye on solar cells future growth. Solar cell can reduce greenhouse gas. Solar power is inexhaustible energy, and solar cell is essential to secure energy for increasing energy consumption future. Silicon solar cell is representation of solar cell. Output power and durability are advantage. But high cost is disadvantage. Solar cell which is low cost is aspired. Dye-sensitized solar cell(DSC) is low cost. Manufacture cost of DSC is one fifth of silicon solar cell. In 1990 Gratzel processor at Swiss Lauanne University presentedDSC. Defect of DSC is conversion efficiency is low. To improve conversion efficiency we treat plasma processing. This paper presents experiment result of plasma processing of DSC.


Development of zeolite electrode for electrokinetic treatment

Department of Electrical and Electric Engineering, Akita Univercity
In recent years, the heavy metal contamination of the soil becomes aggravated in the garbage dump, mine site, etc. And it is needed to purify the contaminated soil promptly and appropriately. One of the purification methods is electrokinetic treatment in which we have focused on the zeolite materials for electrodes as they can adsorb the heavy metal ions. Zeolite is powdered and added with carbon and then pressed. Then the mold is sintered and thus can be used as an electrode. We have succeeded to recover the ions from a heavy metal solution by using this electrode.


Adhesion Improvement and Metal Plating for PTFE Film Using AtmosphericPressure Corona Discharge Induced Graft Polymerization

Masaaki OKUBO*, Mitsuru TAHARA**, Tomoyuki KUROKI and Shinichiro ONO
*Osaka Prefecture University, **Technology Research Institute of OsakaPrefecture
A surface modification technique that improves the adhesion of fluorocarbon polymer films such as PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy fluoroplastics) and PCTFE (polychlorotrifluoroethylene) is developed using -argon at atmospheric pressure and acrylic acid vapor nonthermal plasma. Results of the T-type peeling test show that the peeling strength of the treated PTFE film is approximately over 100 times greater than that of the untreated film. From XPS (X-ray photoelectron spectroscopy) and SEM (scanning electron microscope) analyses, it is confirmed that no chemical connections with F atoms exist on the surface and that a hydrophilic layer is formed due to the plasma graft polymerization process. Using the present surface treatment apparatus, it is possible to bond A4-sized sheets of PTFE and metals without losing the excellent physical properties of PTFE.


On the Study of a RF Discharge Ionic microphone

Hiroshi AKINO, Hirofimi SHIMOKAWA
Department of Electrical and Electronic Engineering , Kanagawa Institute of Technology
This study examined about possibility of the ionic microphone, which works with high frequency discharge. High frequency discharge that is circuit configuration of harmonic oscillator produces plasma, and it moves at particle velocity of the sound wave. Consequently oscillation frequency deviation corresponds to the particle velocity of the sound wave. It was possible to obtain the acoustic signal, when the modulated signal was demodulated. This ionic microphone could response audio frequency range.


Two Dimensional Modeling Experiments for an EHD Pump with Cylindrical-Cylindrical Electrode System

Yamagata University
We have studied on an EHD pump, because of its simple moving part-free configuration, low cost, tiny weight, small size, and electrical controllability. Although a strong EHD effect will be obtain using the ion-drag phenomena, there is serious problem of


An Effect of Wall Material Connecting Electrodes on EHD Phenomena

Graduate School of Science and Engineering, Yamagata University
We have investigated on the electrohydrodynamic (EHD) force due to the hetero-charge density distribution in a cylindrical-cylindrical electrode system under the influence of a DC electric field. The silicone oil added tiny amount of buthyl-alcohol is employed as the driving media, which has both positive and negative charge carriers originally, and shows a remarkable EHD effects. A simple space charge polarization model is introduced, supposing the local permittivity distribution is proportional to the local conductivity, that is, to the mobility and the number density of the carrier. The direction of the electric body force acting on the unit liquid volume driven by this model agrees with that in the experiments. We already confirmed and reported that the model is reasonable. In this report, the experimental results for the tube wall connecting two electrodes on the EHD effect are discussed. The leakage current deforms the charge density distribution, thus the poor insulating substance spoils the EHD effect.


An Estimation of Particle Concentration in Charging Space of the Atomized Electrostatic Powder Coating System

Mitsuru MATSUI*1, Takashi TAKAHASHI*2 and Takashi ITO*3
*1 Zao Electrostatic System Laboratory, *2 Top Industries, Co., *3 I. P. D., Inc.,
This paper describes powder particle concentration in the vicinity of the corona point of powder gun that is directly related to corona quenching. For the atomized powder coating (APC) system, the particle concentration in the charging space can be clearly calculated based on the particle size distribution curve of the powder, because the agglomerated particles are pulverized to the discrete ones with an atomizing unit. For the conventional powder coating (CPC) systems, however powders in that space contain a great many agglomerated particles, and mass of them is dependent on bulk density. Therefore, for the CPC system, the particle concentration is calculated under the assumed bulk density of 0.1 to 1.5. An example of the calculation for the APC system with a kind of general-purpose powder, which was used in the experiments of Q/M measurement, derived the particle concentration 4.28×10^7 [L^-1] for the powder mass flow rate 200 g/min and the conveying air 80 L/min, and which gave the distance 0.286 mm between the particles. In contrast, for the CPC system, the particle concentration remains at a low level of 2.34×10^6 [L^-1], under the same conditions, when the bulk density is assumed as one fifteenth of the true density of the powder. Such large difference in the particle concentration between both the systems leads the difference in corona quenching, and has brought a merit that, for the APC system, occurrences of back ionization are far less than for the CPC systems.


On the optimization of powder coating processes

Tomofumi MOGAMI*, Atsushi OHSAWA**, Nobuyasu SAKURAI***, Kenzou YANAGIDA***
*Kasuga Denki INC, **National Institute of Occupational Safety and Health, ***Asahi Sunac Corporation
Space charge densities in the transport region as well as charge-to-mass ratios of epoxy powder during an electrostatic powder coating with a tribocharging gun have been measured. The aim of this study is the optimization of the transport of powder particles to a grounded target being coated. The results show that the charge-to-mass ratios increase as the transport pressure increases and the supply rate of powder decreases; however, the space charge densities saturates at the transport pressure of higher than 0.3 MPa. It indicates that some of particles with higher charge-to-mass ratios run away from the transport region due to the radial electric field created by field created by charged particles themselves, resulting in the reduction in the transport efficiency of particles to the target. The selective combination of the transport pressure, which not too high, and an appropriate supply rate of powder, which depends on the pressure, may improve the transport efficiency.


High-resolution observation of deliquescence and crystallization of mixture aerosol using electrodynamic balance

Yuuki SAITOU, Hidetoshi KANZAWA, Azuchi HARANO
Faculty of Engineering, Gunma University
The aerosol particle that exists in the atmosphere plays an important role in the control of global warming to absorb and reflect the solar radiation by direct effect and indirect effect. However, because the mixing state of atmospheric aerosol is various, the details content like hygroscopic property of mixed aerosols are unknown. In this study, we mixed NaCl that seems to exist in the atmosphere and CaCO3 of soil component, and we observed the deliquescence and crystallization behavior. As the result, the crystal of shape different from the NaCl was obtained in the NaCl+CaCO3 particle. In addition, we confirmed that the mixture particle of NaCl+CaCO3 have RH point for crystallization more than NaCl point. Therefore, CaCO3 works as a crystalline nucleus of NaCl, and there is a possibility of promoting the crystallization of NaCl.


Selective Oxidation of Carbon Powder using Microwave

Soichiro KAWAKAMI*, Kazunori TAKASHIMA*, Akira MIZUNO* Yoshihiko MATSUI**
Toyohashi University of Technology
In this study, selective oxidation of carbon powder using microwave was investigated for removal of particulate matter (PM) in the diesel exhaust gas. The distribution of electric field is very important for the oxidation using microwave. Carbon powder was placed in the wave guide and irradiated with high electric field of microwave of 2.45GHz, 181W. It was shown that carbon powder emitted glow light and subjected to oxidization to CO and CO_2 in the gas condition (O_2 :10%, N_2 base). It was suggested that carbon oxidization was occurred by selective heating of carbon specifically when the outlet gas temperature was low at 35℃. SEM observation showed that there were submicron spherical carbons on the surface of the carbon powder. The effective carbon oxidation by combination of self-combustion of carbon and microwave was seen in the oxygen concentration of more than 33 %.


CO2 decomposition using atmospheric pressure microwave H2O plasma

Kentaro KODAMA Shigeru ONO
Tokyo Toshi University
:An increase of CO2 becomes a problem world wide.CO2 is known well as a heat-trapping gas and kinds, and the atmospheric CO2 concentration increases in dramatic form since the Industrial Revolution. An increase in the atmospheric CO2 concentration is assumed to be a cause of causing various adverse effects. The seawater side rises by the melt of the ice of Polar regions and the thermal expansion of seawater, and a lot of cities in the coast zone might go under water if the atmospheric level of carbon dioxide keeps increasing. In this research, whether CO2 can be decomposed with H2Oplasma is experimented.


Fundamental Characteristics of Discharge Using Honeycomb Type Discharge Reactor and its Decomposition of Toluene

Yoshiyasu Ehara*, Yoshikazu Ito*, Yujiro Oishi*, Toshiaki Yamamoto*, Yasuhiro Oya**, Masayuki Iwata**,
* Tokyo City University, **Yamatake Corporation
There is problem for health and the environment by chronic exposure of volatile organic compounds (VOCs). Non-thermal plasma technology offers a reformative approach to the problem of removing various VOCs. A toluene, which is one of the most commonly used VOCs, was used and the decomposition characteristics by discharge plasma were investigated. In this study, the toluene decomposition using honeycomb type discharge reactor has been experimentally investigated. Discharge plasma was occurred at end face of zeolite honeycomb. Humidity of the feed gas was considered with discharge parameter on zeolite honeycomb. Discharge pulses were analyzed, the effects of humidity on the toluene decomposition were investigated.


Influence of Catalyst on Trichloroethylene Decomposition by the Atmospheric Non-thermal Plasma

Hidetoshi FUJISAWA, Ryo ONO and Tetsuji ODA
School of Engineering, The University of Tokyo
Trichloroethylene (TCE) decomposition in the dielectric barrier discharge reactor combined with the catalyst was investigated concerning with that amount. In this experiment, the catalyst was settled at the down flow of the reactor. The tested amounts of the catalyst in this experiment are 2000mg, 1000mg, 900mg, 800mg, 500mg, 300mg and 100mg, respectively for the gas flow rate of 1 l/min. As the filled catalyst in the chamber increases, the TCE decomposition efficiency increases even at 2000mg catalyst suggesting the further improvement of the efficiency.


Decomposition of various VOC by using SPCP reactor

Junichi IDA, Tatsushi MATSUYAMA, Hideo YAMAMOTO
Faculty of Engineering, Soka University
In this work, the performance of the SPCP reactor (Surface corona discharge induced Plasma Chemical Process) in decomposition of straight-chain and cyclic saturated hydrocarbons as model VOCs was studied. And, the influence of carbon numbers and structures of hydrocarbons on the performance was examined against various initial concentrations. As the result, in all the kinds of hydrocarbons, the decomposition ratio was higher at the lower initial concentrations. And, it was found that larger carbon number of hydrocarbons showed higher decomposition ratio in both cases of the straight- chain and cyclic structures. Furthermore, it was understood that cyclic saturated hydrocarbons were easier to be decomposed than straight-chain ones.


Effects of Metals Supported on Zeolite as Ozone Assisted Catalysts on VOC Removal

OMasami SUGASAWA, Hyun-Ha KIM, Atsushi OGATA
National Institute of Advanced Industrial Science and Technology (AIST)
In order to elucidate the effect of metals supported on zeolite as ozone assisted catalysts on VOC removal, the decomposition of 200 ppm toluene was carried out by the ozone assisted catalytic oxidation on the Fe, Ni, Ag, Co and Mn supported on ZSM-5 and unsupported ZSM-5. It was found that the performance of toluene decomposition depends on metal species on catalyst and inlet O3 concentration. Consequently, Ag/ZSM-5 exhibited desirable properties such as suppression of HCOOH formation and high CO2 selectivity among the tested catalysts, although the conversion was slightly lower than that on ZSM-5 alone.


Ozone diffusion using SPCP reactor

Junichi IDA, Tatsushi MATSUYAMA, Hideo YAMAMOTO
Faculty of Engineering, Soka University
We developed a new reactor playing both roles as an ozone generator and a diffuser at the same place and time (on-site treatment). The other reactor simulating a conventional ozone diffusion as control was also made (off-site treatment). In this paper, the performance of the new reactor was studied by comparing these two reactors. Experiments using potassium iodide solution showed that on-site system produces ozone in the concentration nearly equal to the off-site treatment at lower energy density, and the higher ozone concentration at the higher energy density. The PCE (perchloroethylene) elimination rates in solution with the two systems showed a pseudo first order kinetics. From the results of ozone concentration dissolved in PCE solution, it was found that the two treatments have about the same contribution of direct ozonation. On the other hand, the apparent rate constant of the PCE elimination was higher in the case of the on-site treatment. It is suggested therefore that the on-site treatment yields the higher contribution of hydroxyl radical oxidation inspired by ozone decomposition.


Development of an electron-beam treatment system of apractical scale VOC gas stream

Teruyuki HAKODA*, Akihiko SHIMADA*, Atsushi KIMURA*, Mitsumasa TAGUCHI*, Koshi ARAKI**, and Koichi HIROTA*
*Japan Atomic Energy Agency, **Valence corporation
An electron-beam treatment system was developed for the purification of VOC gas stream under a practical gas flow condition. This system consists of a compact-sized electron accelerator and a MnO2 catalyst bed. The decomposition and mineralization of toluene and/or xylene were examined with and without a catalytic treatment for gas stream at a flow rate of 500 m3/h. The EB/catalyst system accelerated the decomposition and the mineralization. For example, the mineralization ratio increased from 42% by EB irradiation to 100% by the combination treatment at 9.3 kGy. Furthermore, the yield of CO2 relative to COx increased from 59% to 85% by this catalytic treatment.


Experimental Investigation of DBD with Porous Alumitefor Environmental Cleanup Equipment

Toshiyuki Kawasaki、Yu Jieming Nippon Bunri University
The dielectric barrier discharge (DBD) skillfully combined with (porous) ceramics and/or catalysts has been investigated as the technologies for gas control such as harmful gas treatment and high-efficiency ozone generation. In this study, the porous alumite, which have many pores with nanometer-order diameter and high aspect ratio。B has been focused as the barrier of a DBD reactor. The porous alumite barrier will significantly improve the DBD reactor. However。B the performance of the DBD with the porous alumite barrier (alumite DBD) as a environmental cleanup equipment have not been systematically studied. In this paper。B the NO oxidation and O3 generation characteristics were studied in order to reveal the basic performances of the alumite DBD reactor. The plane-to-plane type DBD was generated by applying A.C. high voltages at the frequency from 50 Hz to 1000 Hz using porous alumite barriers with a thickness of about 140・m. As a result, about 45 g(NO)/kWh NO oxidation efficiency was obtained at NO removal rates above 80% in NO(100 ppm)/O2(20%)/N2, and it is also found that the alumite DBD is effective for ozonizer use.


Basic Study on Treatment of Indoor Air Pollutants by Microplasma (Ⅲ)

Tomoya KUWABARA , Masaki KANAMORI , Marius BLAJAN , kazuo SHIMIZU Shizuoka University
Removal of Volatile Organic Compounds (VOCs) by using of microplasma is investigated, since VOCs are considered as one of the toxic air pollutants of indoor air, and control of these pollutants are a major environmental issue. One of the most common VOCs is formaldehyde, which is known as the main reason of sick-building syndrome. Microplasma is occurred with a pair of electrodes, covered with dielectric barrier, at a relatively low discharge voltage of around 1kV, and has an advantage of reducing the power and downsizing the entire plasma system. In this study, decomposition of low concentration formaldehyde in a 1 m3 box was experimentally investigated, by using a microplasma reactor with a gas flow rate of 100 to 500 L/min. A removal of 40 % was obtained at a discharge voltage of 1.0 kV, discharge power of 20 W.


Measurement of Accumulation Process of Electrostatic Charge on a Single Particle due to Cascade Impacts

T.Matsuyama, D.Ikeno, J.Ida, H.Yamamoto DEES, Fac.Eng., Soka University
We have been working on developments of so called impact charging experiments, in which a single particle is made to impact onto a metal target one by one and the impact charge is measured. In this paper we report our new extension of this concept of the experiment of single particle charging from single impact test to recording cascade impacts of a single particle. The new apparatus consists of two parallel electrodes connected to independent charge amps each. A single spherical polymer particle of 300 micrometer is introduced into the two electrodes system with 45-degree angle, and then successively impacts on the electrodes alternately. The successfully recorded signal showed such alternate and successive impacts on the electrodes, and from the signal the initial charge and the impact charge of the particle in each contact events were determined. The results were well consistent to the results of previous works of the single impact test, and gave the detailed information on the cascade impact event.


Formation of water-in-oil micro droplet using electrostatic field

Hironori AOKI, Thierry. Paillat*, Hirofumi KURITA, Kazunori TAKASHIMA and Akira MIZUNO
Department of Ecological Engineering, Toyohashi University of Technology,University of Poitiers*
Droplet-based micro-reactor systems haves been investigated by many researchers and used for biochemical and combinatorial applications. In these applications, each water droplets in oil perform as a micro-reactors. Magnetic stirrer and homogenizer have been used conventionally to produce water droplets in oil. However these methods have a risk of contamination and require a certain amount of sample volume. In the present study, a method to produce water droplets into oil using electrostatic field has been experimented. Electrostatic atomization was used to produce charged water droplets into oil. Our method can control the size of water droplets by adjusting the applyed D.C. high voltage and these water droplets are stable without surface surfactant due to electrical charge. In addition, these droplets formed a regular array in oil by the repulsive force due to the electrical charge. Our method will be used for biological and combinatorial tools.


Implementation of Electrostatic Functions on Powder Simulation of Desecrate Element Method

T.Matsuyama*, E.Supuk**, H.Ahmadian**, A.Hassanpour**, M.Ghadiri**
*DEES, Fac.Eng., Soka University **IPSE, University of Leeds
Electrostatic charging of spherical beads inside a sealed capsule is induced through a horizontal motion using a shaking device at various frequencies. The particle charge obtained from experiments is incorporated in numerical simulations based on Distinct Element Method (DEM). In the model, the particle charging is related to the contact area of the bead on impact with the capsule wall. The effects of long range forces, space charge effect, and electrostatic boundary condition at the capsule wall were implemented as the electrostatic functions in the DEM.


High Speed Camera Observation of Electrospray of Water

Hyun-Ha Kim, Atsushi Ogata
National Institute of Advanced Industrial Science and Technology (AIST)
In this work, high speed camera was used to observe the time-evolution nature of electrospray of pure water. The DC applied voltage to the spray nozzle was found to be a primary factor determining the property of electrospray. Various modes of electrospray were observed as the applied voltage increased. The sizes of water droplets were mostly determined by the fine structure of spray. It was also found that the size of nozzle diameter is also an important parameter affecting the electrospray pattern.


Electrostatic Charges during Liquid Leakage

Kwang-Seok CHOI, Mizuki YAMAGUMA and Atsushi OHSAWA
Japan National Institute of Occupational Safety and Health
To investigate electrostatic hazards due to liquid leakage, the amount of electrostatic charge during leakage were observed. We deal also with the electric field of the clouds generated by a liquid leakage. Various types of pipeline leakage were designed considering accidents and situations occurring in industrial processes. A leakage pressure in the range of 0.1 to 0.3 MPa was used. With regard to the materials, water for safety in tests of long duration and kerosene was used. As the results obtained from the experiments, the electrostatic charges depend on the leakage parameters such as type of liquid, the material of the gasket between flanges, and pipeline pressure. In all tests, the amount of electrostatic charges of water, 0.12 to 0.83 mC/kg, was a larger than that of kerosene, -0.04 to 0.16mC/kg. The maximum value of the electric field, which was 40.9 V/cm generated from the leakage liquid in this study, is safe level. No incendiary electrostatic sparks, such as brush and/or spark discharges, were detected in our tests.


Presumption of the amount of the Electrical Charge Generation of Hydrocarbon Mixture Oil Gushing out of a Gate-valve

Hiroyuki TAMURA* and Yoshiyasu KITAJIMA**
*National Research Institute of Fire and Disaster, **Funabashi City Fire Department
When hydrocarbon mixture oil gushed from a gate-valve, it experimented to examine how much electrical charge generation. We used not oil but water in consideration of the safety when experimenting. It emitted mist of water by using water in the underground water tank, a pump unit, and the piping model, and the amount of the electrical charge generation was measured. And, the amount of the electrical charge generation of the hydrocarbon mixture oil was forecast based on the amount of water of the electrical charge generation. When the person was exposed gushing oil mist, the electrostatic energy collected in the person was requested based on this forecasted value.


Charging characteristics of the multi-wall carbon nanotubes by the bipolar charge neutralizer

Yoshihiro Sato, Hiromu Sakurai, Kensei Ehara National Institute of Advanced Industrial Science and Technology
The singly-charged fraction of aerosolized multi-wall carbon nanotubes (MWCNTs) was measured in the mobility-equivalent diameter range between about 100 and 300 nm. At each size, the charged fraction was about a half of the fraction of spherical particles of the same mobility-equivalent size. This means that the particle number concentration of aerosolized MWCNTs that is determined by electrical mobility analysis (e.g., SMPS) would be underestimated by about a factor of two if the charged fractions assumed in the analysis were those of spherical particles. The charging-equivalent diameters were estimated from the measured charged fractions and were found to be about 4 times greater than the mobility equivalent diameter.


The influence of the time interval on characteristic of ESD from charged metal

Kentaro KAWASAKI, Takahiro YOSHIDA, Noriaki MASUI Department of Electrical Engineering, Tokyo University of Science
In previous study, the electrostatic discharge (ESD) from charged metal electrode has been measured. The experiment on ESD is carried out by taking interval between discharges ranges from 13sec to 22sec. However, natural ESD is mainly one-shot discharge. In addition, previous report showed that the interval between discharges affects the characteristics of ESD from charged metal. Therefore, in this study, we researched the relationship between intervals of discharges and initial spark gap length in order to find the interval which the discharge characteristic almost equal to that of one-shot discharge. In this experiment, the interval is set from 20sec to 150sec. In addition, in order to investigate the effect of charged particles exists between gaps generated by the last discharge, we also made experiments with irradiation of ultraviolet light to the spark gap as charged particles rich condition. From experimental result, we found follows: 1)The influence of the last discharge on discharge characteristics is very small when the time interval is over 20 seconds in +1kV and +2kV, and over 80 seconds in +4kV,+6kV and +8kV. 2)As the applied voltage is higher, the interval of no influence of the last discharge is longer. 3)When the applied voltage is low such as +1kV and +2kV, the shape of discharge current waveform does not depend on the interval


Charging Evaluation of Optical Devices with Apparatus for Current-Carrying Test

Hiroyoshi KITABAYASHI*, Takashi KOMINAMI**, Megumi TAKEMOTO**, Yoshikazu TANAKA**, Koutarou YAJIMA**
*Mitsubishi Electric Corp. Advanced Technology R&D Center ,** Mitsubishi Electric Corp. High-Frequency & Optical Device Works
Recently in manufacturing process of electronic machinery, the contact electrification of machinery is probable to cause the ESD to the optical devices. And the development of smaller and more sophisticated devices demanded by the fiber-optic communications system also continues. Therefore it is necessary to understand the charging mechanism and to provide the countermeasures to the manufacturing process. So we measured the charging of optical devices (APD) with apparatus for current-carrying test. And we obtained the breakdown value of APD with the apparatus was -2000V.


Effect of the body potential and shape of the grounded electrode on electrostatic discharge from charged human body

Hiroshi YOSHIHARA, Takahiro YOSHIDA, Noriaki MASUI
Department of Electrical Engineering, Tokyo University of Science
In recent years, electrostatic discharge (ESD) causes serious damages to semiconductor devices and electronic equipments. To take measures against the ESD troubles, the elucidation of characteristics of ESD is required. In actual situation of ESD from charged human body, the grounded metals have various shapes and the body potential is different in each time. Therefore, in this study, we research the effects of the body potential and shape of the grounded electrode on discharge current waveforms and photographs of the discharge channel. The body potential is varied from ±2kV to ±8kV. The radius of curvature of the grounded electrodes is from 2.5mm to 20mm in brass sticks and hemispheres, and ∞ in plate electrode. From the experimental results, we found that the appearance rate of the plural peaks discharge current waveform and multiple channels discharge is high when the charged potential is higher and the radius of curvature of finger tip (15mm) is equivalent to that of the electrode. The 1st peak current of ESD with the multiple channels is larger than that with the single channel. ESD with multiple channels was not appeared when the discharge current has three peaks.


Effects of the Waveforms of the Nozzle Voltage on Adhesion Performance of Pesticides to Leaves in Electrostatic Pesticide Spraying

Graduate School of Tottori University
It is well known that electrostatic pesticide spraying is effective to improve the adhesion performance of pesticide to agricultural crops. It was shown in previous researches that when liquid pesticides were sprayed to cultivated fruit trees, most of them adhered to leaves near the spraying nozzle and a few of them adhered to inner leaves because of Faraday-cage effect. In this paper, aiming to weaken the Faraday-cage effect and improve the adhesion of pesticides to such inner leaves of crops, we investigate the effects of the waveform of nozzle voltage on the adhesion performance of the pesticides. It is shown that applying pulse- or rectangular-shaped nozzle voltage may improve the pesticide adhesion performance to the inner leaves of the crops.


Fabrication and Anaysis of Photocatayst layer by Electrostatic Atomization

College of Industrial Technology ,Nihon University
A photocatalyst has useful characteristics such as oxidative decomposition and super-hydrophilicity. In this study, fabrication of photocatalyst layer by an electrostatic atomization was investigated experimentally. Furthermore, the oxidative decomposition effect and the super-hydrophilic effect of the trial photocatalyst substrate were measured.


Basic study on Surface Treatment of Polymer Film by Atmospheric Microplasma

Shizuoka university
Surface treatment of PEN (polyethylene naphthalate) film by atmospheric microplasma was experimentally investigated. Microplasma was generated with a pair of electrodes, covered with dielectric barrier, at relatively low discharge voltage of around 1kV, and has an advantage of reducing the power and downsizing the entire plasma system. Hydorophilization was confirmed measuring contact angle before and after the microplasma surface treatment with argon gas. Analysis by X-ray photoelectron spectrometer (XPS) showed that decrease of C-H bond and increase of C-O-C bond, O=C bond. and O-H bond.


Comparison of the Decomposition Efficiency of Indigo Carmine Using Discharge in Air, Argon or Nitrogen in the Water Treatment by the Pulsed Discharge Plasma Generated in Gas Spraying Water Droplets

Taichi SUGAI*, Yasushi MINAMITANI* and Taisuke NOSE**
*Yamagata University **Sekisui Chemical Co., Ltd.
We have studied the water treatment method spraying water droplets into discharge space generated in air. A discharge electrode for a setup is a coaxial electrode. In this method, to investigate the effect of oxygen existing in the discharge space for the treatment, the decolorization of indigo carmine solution by the discharge in air, argon or nitrogen was measured. Transmittance of the wavelength 610 nm of the indigo carmine solution was measured. Then, the pulse width, maximum value of applied pulsed voltage and current were about 20 ns, about 15 kV and 25 A, respectively. As a result, the transmittance of the indigo carmine came to 90 % by the 14 minutes discharge in air. However the increasing rate of the transmittance by the discharge in argon and nitrogen was 22.5 % and 6 %, respectively. These results show that active species caused by oxygen greatly contribute for the decomposition of organic compounds.


Basic Study of Water Treatment by Low Voltage Pulsed Discharge in Bubbled Water

Shuichi Muramatsu, Marius Blajan, Kazuo Shimizu
shizuoka university
Effective use of water resource is required by a global increase in population and industrial development. Water treatment was experimentally investigated by using low voltage pulsed discharge. Discharge voltage was set at -2.4 kV. Low voltage discharge in the water could be suitable for practical application of water treatment, since its apparatus could be small, inexpensive, and has low power consumption. In order to apply voltage to the electrodes in water, Marx generator with MOSFET switches was used.Discoloration of indigo carmine solution was carried out to investigate the feasibility of low voltage discharge in bubbled water. Air, oxygen, and nitrogen were used as carrier gases to produce bubbles in the water. As a result, indigo carmine solution was decolorized, although the discharge voltage was about -2.4 kV. The treatment performance was improved when oxygen was fed in the solution. This result could be effect of generation of active radical species such as ozone. The discoloration rate of indigo carmine solution increased as the frequency of pulse voltage increased. When frequency was 6.0 kHz, discoloration rate of indigo carmine solution was 50 % higher compared with that of 0.5 kHz.


Generation of pulsed electric discharge in water with aeration and its application

Takanori TANINO,Takayuki OHSHIMA
Department of Chemical and Environmental Engineering, Gunma University
Generation of an electric discharge in water is difficult. In this study, we demonstrated the electric discharge in aerating water. Stainless, titanium and carbon rods and stainless spiral wire are employed as the high voltage and ground electrodes, respectively. Generation of electric discharge was observed in all kind of rod. Moreover, observation with high-speed camera revealed that 46% of applied voltage generated electric discharge in case of using stainless rod as the high voltage electrode. We also tried to decoloration dye with this system, and 100% of dye decoloration was achieved in 20 min reaction. These results confirmed that this novel system was effective for dye decoloration.


Influence of Polarity and Structure of Electrode on Water Purification Using Gas-to-Liquid Discharge Reactor

Katsuyuki Takahashi *, ** Ayako Yonezawa*** Seiji Mukaigawa** Koichi Takaki** Tamiya Fujiwara** Naoya Satta***
*Shishido Electrostatic, LTD. **Faculty of Engineering, Iwate University. ***Faculty of Agriculture, Iwate University
Water purification by streamer discharge using pulsed power generator has been investigated. A gas-liquid separated reactor was employed to achieve high efficiency in the purification. A wire electrode or a barrier type electrode using a glass tube was placed in the gas phase. A tungsten wire or a cupper plate was immersed in the water and was used as a ground electrode. The pulsed high voltage of both polarities generated by the six stacked Blumlein line was applied to the wire electrode to generate streamer discharge in gas phase, which propagated into the air bubble injected into the water. Indigo carmine solution was employed as a specimen. In negative polarity, many weak discharges were observed in vicinity of the wire electrode in the gas phase. Energy efficiency for decolorization of the solution showed higher value at negative polarity than that at positive polarity. An employment of a barrier type electrode was effective for decolorization with high energy efficiency owing to reducing ohmic loss after the streamer bridges the gap between the wire and the water surface.


Surfactant decomposition by discharge plasma in microbubble dispersed water

Takanori TANINO, Fumi NAKAMURA, Takayuki OHSHIMA and Masayuki SATO
Dept. Chemical and Environmental Eng.
Surfactant is essential chemical which is widely employed in the home and industrial scene as the detergent, emulsifier and softener. Surfactants in the wastewater should be decomposed in wastewater treatment. We have been studied discharge plasma in microbubble dispersed water as the AOTs (Advanced Oxidation Technologies) for wastewater treatment. In this study, we demonstrated the decomposition of the surfactant, LAS (Liner sodium Alkylbenzene Sulfonate), by discharge plasma in microbubble dispersed water. The effect of the pore size of SPG (Shirasu Porous Glass) filter membrane to generate microbuble on the decomposition of the LAS was also investigated. Decomposition of LAS by the discharge plasma in microbubble dispersed water was successfully demonstrated, and the LAS decomposition efficiency was increased with the pore size of the SPG filter membrane in the rage of 1 to 10 m. The maximum LAS decomposition efficiency (73%) was obtained with the pore size of SPG in 10 m, because the LAS decomposition efficiency was decreased with the pore size of the SPG filter membrane above the 15 m. These results confirmed that LAS could be decomposed by the discharge plasma in microbubble dispersed water, and the pore size of the membrane is important for the efficient decomposition.