Abstract of Papers Presented to 2006 Annual Meeting of The Institute of Electrostatics Japan

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

25aD-1

“Spark Ignition of Hydrogen-Air Mixture: Measurement of OH Density and Gas Temperature Using Laser-Induced Fluorescence”

The University of Tokyo

○Ryo Ono, Tetsuji Oda

Gas temperature and density of OH radicals are measured using laser-induced fluorescence (LIF) in an incipient flame of hydrogen-air mixture ignited by a spark discharge. When a hydrogen(50\%)-air mixture is ignited with E = 1.35Emin, where E is the spark energy and Emin is the minimum ignition energy, OH density decreases for 100 us after the spark discharge from 2x10(16) cm(-3) to 2x10(15) cm(-3), then it is approximately constant for the next 100 us. On the other hand, the gas temperature increases for 200 us after the spark discharge from 900 K to 1400 K. It shows a heating of the gas by the exothermic reaction of hydrogen-air combustion. The temperature increase is not observed when the mixture is not ignited with E = 0.95Emin.

25aD-2

“Measurement of static charging on anti-static inner bags used with flexible intermediate bulk containers”

*Taiyokogyo Co.，**Shishido Electrostatic,Ltd.，***Technical Institution of Industrial Safety

○Atsushi Yamanobe*，Ken Sawaki*，Tsutomu Kodama**，and Fusao Izumi***

Anti-static flexible intermediate bulk containers (FIBCs) are getting more popular in industry for handling bulky stuffs such as powder and pellets as consciousness of electrostatic hazards with FIBCｓ increases. Various anti-static inner bags are also developed because inner bags have to been used together with FIBCs for contamination free. In order to use inner bags safely, static charging on insulating and anti-static inner bags, which were combined with different types of FIBCs, was measured during discharging of pellets. As a result, the combination of a dissipative inner bag and Type C FIBCs was found appropriate for the safe use.

25aD-3

“Suppression of Incendiary Discharge Occurring from Nozzle-Type Electrostatic Eliminator”

Kasuga Denki,Inc.

Teruo Suzuki

In order to prevent dust explosions in a large silo, we have developed a flange-type electrostatic eliminator, provided with sixteen ionizing needle electrodes, and its performance have also evaluated with the full-size pneumatic powder transport facility. As the results, when a high-voltage DC is applied to the needle electrodes of the eliminator, the performance was superior to the eliminator to which a high-voltage AC (50 Hz) has been applied. On the other hand, the eliminator by abnormal operations can cause rarely incendiary discharges in explosive atmosphere which happens to go on explosions in industry. Accordingly, DC type eliminator remains to be investigated whether it can be controlled safely incendiary discharges. This paper deals with the suppression of incendiary discharges from the DC eliminator by coupling the resistor and voltage supplied to electrode through several ignition tests.

25aD-4

“Prevention of an incendiary brush discharge by a charged cloud in grounded vessels”

Japan National Institute of Occupational Safety and Health

A. Ohsawa

This paper presents required conditions to prevent an incendiary brush discharge between a protrusion on a vessel wall and a charged cloud in the vessel grounded. To obtain the conditions in the charge density of the cloud and the maximum electric field on vessel wall, numerical calculations with different-sized protrusions and cylindrical vessels, which obtains the critical conditions to produce a discharge and also estimates its charge discharged and discharge energy, has been conducted. The protrusion less than 5 mm in the radius of its curvature leads to no incendiary discharge but in its radius exceeding it, an incendiary discharge is possible. In consequently, the obtained condition to reduce the ignition risk by an incendiary brush discharge in vessels less than $\approx 1.5 \times 10^5$ m$^3$ is that the maximum electric field at the vessel wall is less than 1 kV/cm.

25aD-5

“Effect of air flow on formation of a highly-charged particle cloud”

Faculty of Engineering, Yamagata University

Shin-ichi Migita, Kenji Toki, Toshiyuki Sugimoto and ○Yoshio Higashiyama

To form a high-density charged particle cloud ejected by strong air flow, relationship between the electrostatic property of charged particles in the cloud and ejecting velocity was investigated. Radial distribution of charge-to-mass ratio in the cloud showed that charged particles at the outer region of the cloud had larger charge-to-mass ratio and smaller size. Highly-charged small particles tend to move toward outside of the cloud by the electrostatic repulsion force and to adhere to the grounded object. Consequently although charge-to-mass ratio of the particles ejected at the air flow with a velocity of 16m/s was larger than that of 30m/s due to longer charging time, the electric field strength at the ground formed by the cloud was relatively smaller.

25aD-6

“Characteristics of Ignitability for Sprayed liquid due to Electrostatic Discharge”

Japan National Institute of Occupational Safety and Health

〇Kwang-Seok CHOI*, Mizuki YAMAGUMA and Atsushi OHSAWA

The minimum ignition energy (MIE) is a practical index to assess the ignition risk of flammable materials. This paper reports the results of experiments dealing with the MIE due to an electrostatic spark of a sprayed liquid under various conditions. As the samples, four kinds of the liquid - kerosene, n-decane, m-xylene, and styrene - were used. The liquid was pneumatically conveyed to the spray gun with an orifice a 1-mm internal diameter and automatically sprayed for 7 s to measure MIE. The spatial distribution of the MIE in spraying liquid under various conditions was also investigated in this study. The following results were obtained: (1) in the normal temperature range (0 ?C to 30 ?C), all sprayed liquids can be ignited by a spark with discharge energy below 10 mJ irrespective of their flash point. In particular, styrene was ignited with 4 mJ of an electrostatic spark; (2) an optimum region for ignition in a spraying liquid was observed, and it depended on the velocity, concentration, and particle size of the liquid.

25pB-1

“Simulation on Neutralizing Characteristic of AC Corona Discharge Air Ionizer”

The Polytechnic University

○Yuji TSUCHIYA , Kazuo OKANO

The relation between operating conditions and performance of AC corona discharge air ionizer are investigated by computer simulation. The discharge frequency was chosen as the operating conditions. Distributions of charged particle densities and electricfield that are the most important factor for estimating the neutralizing speed and EMI characteristics of the ionizer were chosen as the ionizer’s performance. The simulated results were compared with experimental results. The neutralizing speed slightly depended on the discharge frequency. The electric field decreases with increasing frequency.

25pB-2

“Ultra low-potential elimination by AC Corona Ionizer”

Faculty of Science and Technology Tokyo University of Science

Haruki Sasai

Various corona ionizers are widely used in industry for manufacturing electronic devices in order to prevent electrostatic hazard. However these ionizers could not eliminate charged objects perfectly because of unbalance of positive and negative ions generated by corona discharge. In this paper, for the purpose of low-potential elimination, some experiments are carried out. Concerning to the fluctuation of applied AC voltage, DC bias voltage and air blow velocity.

25pB-3

“Corona discharge ionizer and application to neutralization of static surface charges”

＊Iwate University, ＊＊Hitachi Kokusai Electric

○Masaru OHTANI＊,Seiji MUKAIGAWA＊,Koichi TAKAKI＊,Tamiya FUJIWARA＊,　Takeshi ITO＊＊,Kazuyuki TOYODA＊＊,Unryu OGAWA＊＊

here have been serious problems caused by static charges in electrostatic discharge (ESD) sensitive devices. For its solution the ionizer has been used to neutralize static charges. However, we have as yet some subjects, for example, how to eliminate the charges on many devices for short time. Using a corona discharge ionizer we studied the electrification and neutralization of the charges on the wafer surfaces at N2 atmospheric pressure. In regard to removal of the surface charges, ion balance decreased from ±1kV to around -20V.

25pB-4

“Shielding performance of soft X-ray ionizer with shielding structure”

* Technical R&D Center, Techno Ryowa Ltd., ** Dept. of Ecological Engineering, Toyohashi University of Technology

○Masanori SUZUKI*，Tomokatsu SATO*，Hideaki MATSUHASHI* and Akira MIZUNO**

　　Recently, in semiconductor and LCD manufacturing processes, ionizers have been used that employ low energy X-rays of 3 to 9.5 keV　(soft X-rays), as the ionization source. However, when this ionizer is installed on a　manufacturing equipment, the equipment must be covered with shielding panel to shield the soft X-rays. In addition, this equipment requires safety measures to stop ionizer automatically, when a worker entered a shielding area by any chance. For those reasons, this type of ionizers are inconvenient. Therefore we have conducted the development of soft X-ray ionizer with shielding structure.

In the previous paper, we reported the results of investigation about the structural condition of shielding structure that consists of aluminum honeycomb and perforated plates. In this paper, we report about the structural condition of shielding structure that consists of small pipes. We confirmed that the leakage dose rate of the soft X-rays could be decreased to less than 1 µSv/hr while allowing the passage of enough ion pairs to eliminate the static electricity.

25pB-5

“Relaxation time for air ionization by Soft X-ray”

Ibaraki University 1,The Polytechnic University 2

○Masashi SAKUYAMA 1, Manabu TAKEUCHI 1, Ryuta YOSHINIO 2, Kazuo OKANO 2

Relaxation time for air ionization by soft X-ray was investigated based on the experimental result of the neutralizing characteristic of the jet air ionizer. The jet air ionizer is composed of a stainless steel pipe with an acryl window and a soft X-ray source. The flowing air was ionized by soft X-ray irradiated through the window. The neutralizing speed was measured by the charged plate monitor located at the outlet of the pipe. The relationship between the concentration of charged particle and the irradiation time was calculated by the experimental result to find out the relaxation time. Relaxation time for air ionization by soft X-ray was 12 ms.

25pD-1

“Patterning of nanoparticles on substrate by cluster iondeposition method”

Osaka Prefecture Univeisity, Department of chemical engineering

Hiroyuki Shirai, Motoaki Adachi

The cluster ion deposition method, in which cluster ions are produced from a source vapor by a corona discharge and deposited electrostatically on a substrate are used to arrange nanoparticle on the substrate and form uniformly and quickly a nanoparticle film with a large area. In experiments, a tetraethylorthosilicate(TEOS) is used as source vapor. For nanoparticle arrangement,SiO2 nanoparticle are selectively deposited on charge patterns illustrated by a contact charging method. For nanoparticle film deposition they form uniform films with the density of 1.00e10 cm-2 and the area of 14mm×14mm.

25pD-2

“A Study on discharge current and radiation noise of ESD from charged metal”

Department of Electrical Engineering, Tokyo University of Science

○Takahiro YOSHIDA , Atsushi SUMIDA and Noriaki MASUI

In this study, we measure the discharge current and the radiation noise of electrostatic discharge from charged metal synchronously. In the measurement of radiation noise, three mono-pole antennas are set in vertical, horizontal, and 45 degree. When the discharge current has single peak, the high frequency component around 700MHz-900MHz appears on the wavefront of the discharge current and radiation noise. When the discharge current has 2 peaks, frequency component of discharge current and radiation noise are around 200MHz. The amount of charge including radiation noise is equal between positive discharge and negative discharge. In positive discharge, the amplitude of radiation noise from the antenna set in horizontal is a maximum. In contrast, in negative discharge, the minimum amplitude of radiation noise is obtained from the antenna set in horizontal.

25pD-3

“Technology of Charging Control in Conveyance Manufacturing Process of Electronic Machinery on the Basis of the Effective Work Function”

Mitsubishi Electric Corp. Advanced Technology R&D Center

Hiroyoshi KITABAYASHI

Recently in manufacturing process of electronic machinery, the contact electrification of machinery is probable to cause the ESD to the semiconductor devices in the electronic machinery. In particular, this phenomenon can be confirmed in conveyance process of machinery manufacturing. Therefore it is necessary to understand the charging mechanism and to provide the countermeasures to the contact of electrification. It is known that contact electrification is related to the effective work function of materials. When materials with equal work function came in contact, there is little charge generated between materials. So we measured the effective work function of the materials which are used for the machinery and suggested the material of the apparatus which was not charged even if the machinery was contacted.

25pD-4

“Effects of the relative humidity on ESD from the charged metal”

Department of Electrical Engineering, Tokyo University of Science

○Atsushi SUMIDA, Takahiro YOSHIDA and Noriaki MASUI

In this paper, by using spherical electrodes (20mm in diameter), effect of applied voltage and relative humidity on the short air gap discharge is discussed experimentally. The humidity of the discharge space is 2%RH and 40%RH. Applied voltage is from +2kV to +9kV. Material of the electrode iscopper and brass plated with chromium. Earth electrode approaches the high voltage electrode at 0.4mm/s and spark discharge is occurred. When the humidity is 2%RH, the gap length of discharge inception is shorter than that in 40%RH. The waveform of discharge current depends only on the breakdown field strength. When the applied voltage is from 2kV to 4kV, discharge current having almost the same waveforms are obtained for the change in the relative humidity.

25pD-5

“Relationship between waveforms of discharge current from the charged human body and discharge pattern on the fingertip”

Department of Electrical Engineering, Tokyo University of Science

○Hiroyuki TAKAZAWA , Takahiro YOSHIDA and Noriaki MASUI

In this paper, the relationship between waveforms of discharge current from the charged human body and the discharge channel appeared between fingertip and earth electrode is discussed. The body potential is from ±2 kV to ±10 kV. When the applied voltage becomes low, the multiple discharge channels are appeared between fingertip and the earth electrode. These channels are appeared at the very high probability, when applied voltage is lower then 4kV. When the applied voltage is higher than 5kV, single discharge channel is appeared in most case. The summary of the mechanism of the generation of these channels is examined.

25aA-1

“Elastic Control of piezoelectric PZT Ceramics”

Grad. Sch. of Eng., Kansai Univ., Imoto Mech. Eng＊., Kobayashi Inst. of Phys. & Chem＊＊

Komei TAHARA, Hiroaki UEDA, Kenji IMOTO＊, Munehiro DATE＊＊, Eiichi FUKADA＊＊, Yoshiro TAJITSU

We report a novel elasticity control technique for piezoelectric lead zirconate titanate (PZT) ceramics using an electric circuit that behaves as a “negative capacitor” (hereafter referred to as a negative-capacitance circuit) for application to the sound shielding technology. A feature of this technology using an optimized negative-capacitance circuit is effective sound attenuation regardless of the PZT ceramic type or frequency ranges of the noise. In this experiment, we prepared three types of PZT ceramic with different dielectric and piezoelectric characteristics. We improved the circuit constants of negative-capacitance circuits for the three kinds of PZT ceramic with different physical properties. We measured the transmission loss attenuation factors of the three types of PZT ceramic in the frequency range from 1 kHz to 100 kHz. We found that the transmission loss attenuation factors in of all three types of ceramic were greater than 20 dB in the frequency range from 1 kHz to 100 kHz.

25aA-2

“Piezoelectricity of Chiral Polymeric Fibers”

Grad. Sch. of Eng., Kansai Univ.

Masahiro HONDA, Kazuto HAYASHI, Masayoshi KANASAKI, Yu MORIMOTO and Yoshiro TAJITSU

Chiral polymers have recently attracted attention as a polymer which exhibits a high shear piezoelectric constant. Chiral polymers are not ferroelectrics but piezoelectrics. Also, to realize piezoelectricity throughout the entire chiral polymeric fiber, the chiral polymeric fiber does not require poling treatment. On the other hand, the chiral polymeric fiber shows the very small piezoelectric constant. Its value is 1/100 or less compared with that of inorganic ferroelectrics and piezoelectrics. However, we succeeded in controlling the piezoelectric motion of the chiral polymeric fiber by applying dc voltage and ac voltage similar to a piezoelectric actuator.

25aA-3

“Nonlinear Permittivities in Potassium Salt Ionomers of Ethylene Copolymer.”

○*Technical Center, DuPont Mitsui Polychemicals Co., LTD.、

**Graduate School of Engineering, Kansai University

Nobuyuki Maki

We report the frequency spectra of complex linear and nonlinear permittivities of potassium ionomer films prepared from poly (ethylene-co-methacrylic acid) in the frequency range from 1 kHz to 1 MHz, at room temperature. A characteristic conduction relaxation phenomenon was observed in the spectra, which suggested the existence of different ion conduction mechanisms between the high and low-frequency regions. We also found that the ratio of linear to nonlinear conductivities calculated from nonlinear permittivities was closely related to the elementary process of ionic transport. Furthermore, the ratio obtained from nonlinear measurements allowed an estimate of the important parameters which characterized ionic transport in ion-conducting polymers, such as the hopping distance of ion or the size of a connected cluster of the site capable of the ion hopping, without the need for any additional assumptions in potassium ionomer films.

25aA-4

“Change in Charging Characteristics of Polymer Powder with Very Small Size”

Faculty of Science & Technology, Tokyo University of Science

○Yusuke KUDO, Takayoshi SAITO, Yuji MURATA

Change in characteristics of contact and frictional charging of polymer powders with very small size after treatment in O2 gas plasma was investigated. When the very small polymer powders were treated, the powder particles tend to adhere to electrodes and their treatment efficiency deteriorate. It was found that treatment efficiency could improve by applying DC bias voltage to GND electrode. Obtained surface charge density of the treated powder particles kepts constant regardless the diameter of the particles.

25aA-5

“Thermally Stimulated Surface Charge Decay easurements in Polymer Powder Layers”

Department of Electrical andElectronicEngineering,Ibaraki University

○Akihiro Suzuki　Manabu Takeuchi

Thermally stimulated charge decay (TSCD) measurements were carried out on polymer powders to investigate the charge traps. A polymer powder layer was formed in a metal sample holder, and its surface was corona charged, and the decay of the surface potential was recorded when increasing the temperature. A spherical acrylic powder (10m) was used in this study. It was confirmed that TSCD measurements give similar information concerning charge traps in polymers as TSC measurements. The corona charging time was changed from 5s to 100s. The corona charging for 30s was sufficient for filling all the traps by charge carriers. Heat treatments of the polymer powders changed TSCD spectra.

25aA-6

“Effect of crystal face on triboelectrification using a single crystal ice”

Hokkaido Univ. of Education

Hisashi Shio

25aA-7

“Charged fog generated by ultrasonic atomization of pure water”

Kanagawa Institute of Technology

Takahiro SATO Hirofumi SHIMOKAWA

This study examined the electrification quantity of the fog in doing ultrasonic atomization of pure water. In the water of lowpurity, the electrification fog in proportion to the induced voltage polarity arose. However, in the water of high purity, the electrification fog of the negative polarity arose without relating to applying the negative induced voltage. Especially, it was found that the negative charged fog arose, even if the induced voltage was not applied in the high-pure water. From this fact, when the purity of the water rises, the electric double layer which exists in air/water interface, seems to have firmly been formed.

This fact was supported from the measurement results in mixing the surfactant.

25pC-1

“Basic Experiment on Electrostatic Pesticide Spraying to Fruit Tree”

Electrical and Electronic Engineering, Tottori University

○Tomoya NISHIKAWA,Kazuya NISHIO,Ryo NISHIMURA,Katsumi NISHIMORI,Naganori ISHIHARA

We quantitatively measured the effectivity of electrostatic pesticide spraying. We sprayed the solution of edible dye in water to potted Japanese pear trees from a spray nozzle that high voltage (-50 kV) was applied. The nominal pumping pressure and rate of the spray are 2.7 atm (2735 hPa) and 4.48 cm3/s, respectively. The distance between the trees and the nozzle was 120 cm. We measured the volume of the water droplet on the pear leaves after spraying. In the case when the voltage was not applied to the nozzle, the 0.52% of the sprayed water adhered to the leaves. On the other hand, when -50 kV was applied to the nozzle, the adhesion rate was improved to 2.6%.

25pC-2

“Electrostatic potential of spray target coated by metallic spray”

*Yamagata university **Alpha techno-tool co. ltd.

Toshiyuki Sugimoto*, Noriyuki Shirahata*, Yoshio Higashiyama*, Koichi Takeda**

Spray charging of metallic paint has been investigated by measuring electrostatic potential of a spray target. The metallic paint was sprayed by a commercial air spray gun with and without Induction charging method. The potential of the sprayed plate was drastically increased up to + 4 kV without induction charging by the spray charging of the metallic paint. The electric current flowing through the spray gun was significantly small compared to the potential rise of the target. The result indicates that small spray particles are charged negatively and large particles are charged positively. Because the airflow including the paint particles is deflected by striking the target, small particles loose a chance of adhesion to the target. The large particles mainly adhere to the target, resulting in the positive potential rise. Negative dc high voltage to the spray gun could control the target potential due to the induction charging.

25pC-3

“A Discussion on Optimizing the Operation of the Atomized Electrostatic Powder Coating System”

*1 Zao Electrostatic System Laboratory, *2 Top Industries, Co., *3 I. P. D., Inc.,

Mitsuru MATSUI*1, Takashi TAKAHASHI*2 and Tsutomu ITO*3

This paper describes a discussion on optimizing the operation of the atomized electrostatic powder coating (APC) system by increasing the amount of the conveying air, which affects strongly to penetrating of powder inside recessed areas and electrostatic wrap effect. For most of the conventional coating systems, the conveying air of 80 l/min has been recommended as an empirical standard value. However, an experimental investigation using the APC system with a fine particle powder resulted in about 13% of increase in coating thickness, when the amount of the conveying air was increased from 80 l/min to 120 l/min. It can be considered that the increase in coating thickness is brought by intensifying the corona charging efficiency for powder particles due to the increase of the conveying air.

25pC-4

“Charging Characteristics of Coating Powders (�T)”

Department of Electrical andElectronicEngineering,Ibaraki University

○Ken-ichi Kanai, Takahiko Kurisaki, Manabu Takeuchi

Fundamental electric properties of coating powders, consisting mainly of polymers and pigments, were investigated to improve performance of electrostatic powder coating. Surface potential decay after corona charging were monitored in polymer coating powder layers. Apparent resistivities and charge to mass ratio q/m of polymer coating powders were also measured. The surface potential decay was faster in the normal polyester powder than the powder, which was not deposited on a substrate in the electrostatic powder coating. The charge to mass ratio was smaller in the powder not deposited on a substrate than the normal powder.

25pC-5

“Improvement of the Charging Process for High-speed Electrophotography(�U)”

Faculty of Science and Technology Tokyo University of Science

Daisuke YAMASHITA

This study concerns to the improvement of the charging system for high-speed electrophotography. For the purpose, the possibility of increasing charging speed was examined using a charging system with wire electrode. When the distance d of wire electrode and drum surface comes close to 3mm, corona current was 54μA/cm at surface potation of -800V, and the charging speed was 540PPM. The Charge distribution on the drum surface was also investigated.

25pC-6

“Fundamental Study on Electrostatic Demulsification Process of Small Volume W/O emulsion”

Toyohashi University of Technology

○Michihiko NAKANO，Akira MIZUNO

Water-in-oil (W/O) emulsion has been applied to biological and chemical reactions. We previously showed a new emulsification method using AC electric field that was suitable for the application of W/O emulsion. Because electrodes were placed outside of the vessel, a non-contact process was realized to avoid any contamination. In this paper, fundamental study on demulsification processes using electrostatics was described. We used small plastic tubes of 0.2 mL in volume. The electrodes were placed outside of the plastic tube. 0.2 mL of W/O emulsion in the vessel was demulsified by AC electric field through pear-chain formation of the droplets. Two electrode configurations were tested, with two different frequencies of AC voltage (60 and 17 kHz). Each experiment showed the AC electric field enabled to demulsify, however, it took more than 10 min. With higher frequency, the demulsification was more effective.

25pC-7

“Electrostatic Process in Liquid-Liquid System (II) -Resolution of W/O Emulsion by Bipolar Charging Method-”

Department of Electrical and Electronic Engineering，Oita University

Yusuke Seiji Seiji KANAZAWA, Yuusuke TAKAHASHI

Demulsification of W/O emulsion was studied by the injection of bipolar charged water droplets. One nozzle electrode with positive dc high voltage was produced positively charged water droplets, while other nozzle electrode with negative dc high voltage was produced negatively charged water droplets. The atomized water droplets with both polarities captured the suspended water droplet in the emulsion and then collide with each other. The aggregation droplets fell down due to the gravity as well as EHD flow effect, resulting in the separation of water and oil. The test liquid, which was prepared by the electrostatic atomization technique, was maintained a state of emulsion for longer time if no electric field was applied. When the bipolar charged droplets were injected into the test liquid, the emulsion with a dull color gradually became transparent as a time elapsed. The demulsification promoted until the water content became less than 0.04%.

25pC-8

“Positive Polarity Operation Characteristics of dc Wire-Non-Parallel Plate Type Electrohydrodynamic Gas Pumps”

＊McMaster University、＊＊Osaka City University、†Ariake National College of Technology

Ueno JUN＊,＊＊、Hiroaki TSUBONE＊.†、B. KOMEILI＊、Shigeyuki MINAMI＊＊、G. D. HARVEL＊、○Kuniko URASHIMA＊、J. S. CHANG＊

The effects of positive polarity applied voltage on velocity profile, pressure rise and volume flow rate for wire-non-parallel type EHD gas pump were experimentally investigated and analyzed by dimensionless parameters. The experiments were conducted at atmospheric pressure and room temperature, where air was used as the working fluid. Experimental results show that; (1) Depending on electrode position, the maximum gas velocity 1.3 m/s and volume flow rate 19.3 l/min were observed; (2) The volume flow rate, pressure drop and velocity increase with increasing applied dc voltage or EHD number.

25pC-9

“Miniaturization of a Stacked-type Electrostatic Actuator”

Tokyo Institute of Technology

○Tatsuro TAKSHIGE,　Yoshiyuki HATA,　Motoki TACHIIRI,　Keiji SANEYOSHI

We are developing a stacked-type electrostatic actuator that generates contractile force for purpose of the artificial muscle. This actuator is made of two ribbon-like films. We alternately fold the two films and fabricate the actuator just like a paper spring. The electrostatic force is inversely proportional to the square of the distance between two electrodes and proportional to the dimensions of the electrode, as this actuator has the condenser structure. Therefore, it is effective to miniaturize the films. And it result in producing more strong force. In this paper, we report fabrication of the film that the dimension of electrodes is as large as possible by etching. This method will be good to make more minute film. We fabricated the actuator using the films 0.7mm width, and drive it at 600V.

25pC-10

“Basic Research on Disk Type Corona Motors (�])”

*Sendai National College of Technology ，**Shishido Electrostatic, Ltd.

M. Hattori*, K. Takahashi*, S. Miura*,T. Oizumi*, and K. Izumi**

In our previous report, a multi-disk-type corona motor comprising a multi-DVDs (Digital Video Disk) rotor and a number of dual-printed circuit boards stator was proposed and tested for its torque-generating characteristics. Each stator board has 20 discharging electrodes and a partial slit to allow the rotor to be inserted and extracted without disassembly. To use the corona motor, an ozonic water generation system was constructed and tested, however, liquid ozone (ozonic water) density generated was very low and a higher density of gaseous ozone was needed. This time, an ozone density regulator was proposed and tested, which can conduct about one-tenth of the density of the gaseous ozone to the ozonic monitor, in order to blow higher density gaseous ozone into the ozonic water.

25pB-6

“A study of Si-MIS structure with a mixed SrTiO3−Al203 insulating layer”

Kazuo HATTORI*, Noriyuki Nakajima*, and Akira MIZUNO**

*Department of Electrical and Electronic Engineering, Toyohashi University of Technology, **Department of Ecological Engineering, Toyohashi University of Technology

Electronic devices such as DRAM and VLSI consist of Si metal-insulator-semiconductor （MIS）structures. As insulating layers, SiO21ayers have excellent electrical properties．As the memory cell areas decrease, thickness of the insulating layers should be decreased to form large capacitances. Strontium titanate

（SrTiO3）shows a high relative dielectric constant at room temperature. Accordingly, SrTiO3 layer is a very good candidate to form large capacitance instead of thin SiO2 1ayers．The purpose of this study is to fabricate Si-MIS structure with good electrical properties. Mixtures of SrTiO3 and Al203 are used to form

an insulating layer: The diffusion of A1203 into SrTiO3 1ayers is carried out to decrease the dissipation factor of SrTiO31ayers．The SrTiO3 powder was ground with ball mill until its grain size became less than l μm in diameter．The SrTiO3 powder was deposited on a p-type Silicon substrate using corona discharge. The

powder on the substrate was humidified by vapor of water and heated in a wet oxygen atmosphere at 900℃ for 3.5h. Aluminum was deposited on the SrTiO3 1ayer by vacuum evaporation as a starting material of Al203． The deposited Al was dissolved by vapor of nitric acid（HNO3）and heated in a wet oxygen atmosphere at 500℃ for l.5h to form Al203. The obtained Al203 was diffused into the SrTiO3 layer in a wet oxygen atmosphere at 800℃ for l.5h. After that，Al dots of l mm diameter were evaporated as a gate electrode. The thickness of the insulating layer thus obtained was approximately 400nm. The C-V characteristics were measured for the bias region from inversion（＋1V）to accumu1ation（−10V）in the frequency range 100 Hz〜1 MHz. The maximum of relative dielectric constants was10.7 at 100 Hz and the minimum of dissipation factors was 0.016 at 4 kHz. The hysteresis in the C-V curves at l MHz were measured with very slow speed: It took l.5h for the measurements. The hysteresis was found to be less than 0.15 V of an ion drift type. The surface-state densities were estimated by applying Terman method to the C-V curves at l MHz. The surface-state densities around the mid gap of Si were estimated to be in order of 1010eV-1cm-2. These results show that the fabricated Si-MIS structure with an insulating layer composed of SrTiO3 and Al203 has fairly good electrical properties.

25pB-7

“Numerical Simulation on Streamer Propagation in Nanosecond Pulse Corona Discharge Induced Nonthermal Plasma for Pollution Control”

Department of Mechanical Engineering, Osaka Prefecture University

Masaaki Okubo and Toshiaki Yamamoto

Numerical analyses are conducted on a nanosecond positive pulse dielectric barrier discharge-induced nonthermal plasma (NTP) for pollution control. In the numerical analysis, a commercial simulation software, CFD-ACE+ solver, is used. One-dimensional simulation results indicate that a streamer progressing from the positive electrode to the grounded one is well simulated. At the end of the pulse, the electron temperature and electron number density in the coaxial-type plasma reactor finally reach approximately 1.7 eV and 10^15 m-3, respectively. The radial electric field is almost constant in the plasma region. During the single pulse, the peak concentration of ozone is approximately 40 ppm near the surface of the glass barrier. Further, in the two-dimensional simulation result, the streamers propagation (1st and 2nd) can be simulated well numerically.

25pB-8

25pB-9

“Measurement of OH Radicals in Atmospheric Pressure Corona Discharge by Laser-Induced Fluorescence (II)”

* Department of Electrical and Electronic Engineering, Oita University ** Institute of Fluid Flow Machinery, Polish Academy of Sciences *** Department of Engineering Physics, McMaster University

Seiji Kanazawa*, Hiroto Tanaka*, Toshikazu OHKUBO*, Marek Kocik**，Jerzy Mizeraczyk**，Jen-Shih Chang***

The LIF measurement of the hydroxyl (OH) radicals in the reactor with a nozzle-to-plane electrode system having an electrode gap of 30mm was performed. The LIF signal in DC corona streamer discharge can be obtained with a properly adjusted timing of the ICCD camera taking into account of the time relationship between the regular streamer, probe laser, and laser-induced streamer. As a result, the ground-state OH radicals were observed during the steady-state positive streamer corona discharge. OH LIF signal was detected along the laser beam path not only in the discharge region but also outside of that region. The influence of ozone on the OH LIF signal was investigated experimentally.

25pB-10

“Fundamental Experiments on a Silent Discharge Reactor with Anodic Porous Alumina for Gas Treatment”

Department of Electrical and Electronic Engineering, Nippon Bunri University

Toshiyuki Kawasaki

The simultaneous treatment of gaseous pollutants and suspended particle matter (SPM) exhausted from a diesel engine is one of the most serious problems in our living environment. Non-thermal plasma skillfully combined with ceramics, for example DPF, is very attractive for the simultaneous treatment. In this study, we focused on the silent discharge plasma reactor used anodic porous alumina, which have many pores for collecting SPM, as a barrier.

A purity 99.99% Al sheet was electropolished under a constant current condition of 100mA/cm2 below 5℃ for 2.5min in a mixed solution of HClO4 and C2H5OH after a buffing. Then, the anodization of Al was carried out in 0.3M or 0.5M sulfuric acid under a constant voltage condition of 24V at about 4℃ or 20℃. Two anodic porous alumi