Abstract@of@All@Papers@Presented@to 2004 Annual Meeting of The Institute of Electrostatics Japan

 

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

 

16aB-1 

Removal of formaldehyde in the corona discharge with needle electrode and the catalyst honeycomb

Mitsubishi Electric Corporation   

Takuya FURUHASHI, Akira SHIGA, Shiro TAKEUCHI and Yoji FUJITA      

The removal rate of formaldehyde, the ozone generation and also the conversion rate of formaldehyde to carbon dioxide in the corona discharge reactor was investigated. This reactor was composed of a needle discharge electrode and a conductive manganese oxide catalyst honeycomb. The result showed there was an optimal needle configuration for the maximum formaldehyde removal and the least ozone generation. Moreover, the conversion rate of the formaldehyde to the carbon dioxide at the optimal needle configuration was proportional to the square root of the relative specific input energy.   

 

16aB-2

Examination of conversion of paraffin into olefin by electrical discharge plasma

Mitsubishi Electric Corp. Advanced Technology R&D center 

Masato KURAHASHI, Hiroaki SHIGEOKA, Sho SHIRAGA, Minoru SATOH, Kazuhiko KAWAJIRI and Masaki KUZUMOTO      

Conversion of paraffin into olefin by electrical discharge plasma has been studied. Propane as paraffin is diluted by Air consists of 90% nitrogen, 10% oxygen and 28,000ppm waterCand propane concentration is 500ppm. O* and OH* radicals are generated by electrical discharge in a coaxial barrier discharge reactor which is keeping at 600Ž. Propane is oxidized by radicals and converted into propene and ethylene. Olefin with a concentration of 180ppm are generated@with specific energy density of 46.8J/L. When the temperature of the reactor is under 550Ž small amount of olefin are generated. Up to 650Ž, olefin are decreased@and@CO and CO2@are@generated@from@olefin.

 

16aB-3 

Formation of Charged Particles in Air Containing o-Xylene under Electron Beam Irradiation

Takasaki Radiation Chemistry Research Establishment, Japan Atomic EnergyResearch Institute        

Teruyuki HAKODA, Akihiko SHIMADA and Takuji KOJIMA           

Electron beam (EB) irradiation of aromatic hydrocarbons and humid air mixtures leads to toxic particles in the size of about 100 nm and gaseous organics such as organic acids. The particles should be removed from gas phase, for example using electric field after their charging, for the detoxification of irradiated air mixtures. In the present work, a few tens keV electron generator was developed to study the formation process of charged particles in irradiated humid air containing o-Xylene at initial concentrations of 10 and 30ppmv. After EB irradiation to an absorbed dose of 9.8 kGy, yields of particles and gaseous organic were 65-68% and 16-17% of irradiation products on the basis of carbon, respectively. Yield of charged particles was about 50% of total particles on the basis of number concentrations. There was no difference in the number concentrations as a function of size between positively and negatively charged particles.

           

16aB-4 

Oxidation of dilute Trichloroethylene by using Barrier Discharge Process combined with Manganese Dioxide

University of Tokyo

 SangBo Han and Tetsuji Oda     

In order to oxidize into small molecules of COx in the decomposition of dilute trichloroethylene, the barrier discharge process was studied experimentally. It was carried out by arranging catalyst of manganese dioxides at the downstream of plasma reactor. Decomposition efficiency was improved about 99% at the specific energy of 40J/L with passing through manganese dioxide and 98% of COx yield (CO and CO2) was attained at about 400J/L. In addition, this barrier discharge process was suppressed the generation of NOx (NO and NO2). This process is considered as very desirable way to increase decomposition efficiency and oxidize into COx along with the decrease of energy consumption.@@@Keywords: trichloroethylene, barrier discharge, manganese dioxide

           

16aB-5 

Decomposition Characteristics of VOCs by a Dielectric Barrier Discharge     

–Institute of Fluid Science, Tohoku UniversityC––Graduate School of Engineering, Tohoku University (Presently, IBM Japan, Ltd.)       

Takehiko SATO–, Makoto KAMBE–– and Hideya NISHIYAMA–

1. Experimental and numerical analyses have been adopted to clarify the key radical of the methanol decomposition process.

2. In experimental analysis, it is clarified that the DBD system decompose the methanol, ethanol and styrene completely below 50 ppm at discharge conditions as V = 16 kVpp and f = 100 Hz.

3. In numerical analysis, it is clarified that OH is an important radical to decompose the methanol. "    

 

16aB-6 

Optimization of Plasma-Driven Catalysis for the Decomposition of Benzene@Using Ag/TiO2 Catalyst  

National Institute of Advanced Industiral Science@andTechnolgoy(AIST)*C Dong-A University**        

Hyun-Ha KIM, Jeong-Uk Park, Seung-Min Oh, Kum-Chan Choi, Atsushi OGATA, Shigeru FUTAMURA 

Decomposition of benzene was investigated using plasma-driven catalyst (PDC) reactor packed with Ag/TiO2 catalyst. The influence of reaction temperature@on the benzene decomposition and the yields of reaction products indicated that the formation/decomposition of formic acid (HCOOH) played an important role in the benzene decomposition using the PDC reactor. The presence of water vapor decreased the decomposition of benzene in the PDC reactor. Water vapor had no effect on the COx (CO+CO2) selectivities. In contrast to the conventional plasma reactors (dielectric-barrier discharge and BaTiO3 pellet packed plasma reactor), the PDC reactor showed extraordinary dependence to the oxygen partial pressure. Decomposition efficiency of benzene increased with increasing oxygen partial pressure, while no influence with the DBD reactor and the BaTiO3 pellet packed plasma reactor above 20%. Based on this highly oxygen partial pressure-dependent behavior of the PDC reactor, oxygen plasma was investigated as a method to regenerate adsorbent/catalyst.          

 

16aB-7 

Oxidation of Carbon Monoxide by Using A Barrier Discharge

*Department of Electronic Engineering, University of Tokyo@**Midori Anzen.

Tetsuji Oda , Taisuke Murata, Koichi Ono, SangBo Han, Tomoyuki Saito       

Carbon monoxide is very poisonous gas for a living being but is easily produced in many human activities.   Examples are human smoking and firing in insufficient oxygen condition.  One simple method of nonpoisonization of carbon monoxide is oxidation.  Carbon monoxide can be oxidized to carbon dioxide which causes green house effect but not so harmful directly for us.   Barrier discharge should be a good oxidation process of carbon monoxide but experimental results suggest the oxidation is very weak.  At the best condition combined with manganese oxide, half carbon monoxide was oxidized to carbon dioxide.  

 

16aB-8 

Characteristics of Precipitation Efficiency and Gas Velocity for Electrostatic Precipitator of Special StructureiPart3j  

Fukui University of Technology    

Ayumu Iijima    

On the 2003 Annual Meating of this Institute, the auther reported the charactristics of precipitation efficiency and gas velocity for the electrostatic precipitator of special structure (part 2). It is investigated on the collection efficiency that made by the comparison between the electrostatic precipitator of single type and the proposed structure. As a result, it is found that by comparing with the single stage type, the proposed structure obtained good collection efficiency. Application of the proposed structure is expected to lead to a reduction in the size of precipitators.

           

16pS-1

Some Basic Plasma Technoloties for Application@Tohoku Univ.       

Noriyoshi Sato

The author has been interested in basic plasma technologies necessary for next-stage plasma application. Here some of related plasma technologies proposed up to now are presented, which are concerned with plasma production, electron-temperature control, and collection and removal of dusty fine particles. Most of them have already been well established for plasma application. Drastic results based on those plasma technologies are also described.

 

16pC-1             

Yamagata University

                       

16pC-2 

Droplet actuation based on single-phase electrostatic excitation       

–:Dept. of Mechanical Eng. The Univ. of Tokyo,  ––: Shimadzu corp.

Masahide Gunji(–), Hiroaki Nakanishi(––), Masao Washizu(–)   

A new concept of electrostatic droplet actuation based on field-induced deformation of the droplet is presented in this paper. The device consists of a diagonal fishbone-shaped electrode array with a hydrophobic coating. When energized with an AC voltage, a droplet dispensed on the electrode undergoes a periodical motion of flattening and restoring the spherical shape, and because of the geometrical asymmetry of the electrodes, its center of mass is shifted bit by bit in each cycle. The actuation speed as high as 2.4 cm/s is achieved for a 1 l-droplet on a 240 m-pitch electrode array with 50 Hz, 50 Vrms excitation. Droplet sorting and mixing are also demonstrated by bifurcating and merging electrode arrays. The method only requires a pair of planar electrodes that can be fabricated by a single-mask process, and a single-phase power supply, leading to a simple and low-cost droplet-based micro-chemical system

 

16pC-3

Stability of Charged Emulsion in Water

Graduate School of Engineering, Hokkaido University

Tsuneki Ichikawa and Yoji Nakajima

The energy barrier preventing the coalescence of two charged emulsion droplets in water has been theoretically obtained in the framework of the DLVO theory in which the rearrangement of surface charges during the approach of the droplets is taken into account.

 

16pC-4 

Properties of Droplet Formation using a Novel Capillary with an@External Electrode

*Hamamatsu Photonics K.K., **Toyohashi University of Technology   Osamu Yogi*,**ATomonori Kawakami*AAkira Mizuno**   

A capillary with an external electrode for cone-jet mode of electrospray has been developed  to spot a droplet  accurately on a substrate surface. The external electrode is made by gold deposition around tip of a glass capillary. The electrospray was made  by applying a positive pulsed dc voltage to the solution in the capillary. Using a positive bias voltage to the external electrode, the meniscus of the solution at the  tip  deformed  to  be more sharp, and center of the meniscus was prolonged. This deformation stabilized the trajectory of the jet from the meniscus called Taylor cone at the tip. From the experimental results, accuracy of positioning of the droplet  having  0.3  pL  volume was improved with the standard deviation of 1.1micrometers, from  that  of  2.5  micrometers for conventional capillary without the external electrode.

 

16pC-5 

High sensitive detection of Escherichia coli by impedance measurement using

Graduate School of Information Science and Electrical@Engineering, Kyushu University          

Tetsuji HATANO, Junya SUEHIRO, Masanori HARA         

This paper describes a high sensitive detection method of micro-sized@bacteria using a dielectrophoretic impedance measurement method assisted by@electropermeabilization. The authors have previously proposed a bacteria@detection technique called DEPIM (dielectrophoretic impedance measurement)@method using positive dielectrophoretic force to capture bacteria in@suspension onto an interdigitated microelectrode array. In the present@study,  electropermeabilization (EP) was combined with DEPIM in order to@improve the sensitivity as a result of intracellular ion release through@damaged cell membrane (EPA-DEPIM). The EP pulse parameters were optimized so@that conductance increase caused by electrolytic ion release from metal@electrodes could be suppressed. This enabled a secure detection of@intracellular ions released from bacteria avoiding disturbance of@electrolytic contamination from metal ions. Consequently, the lower limit of@EPA-DEPIM sensitivity for Escherichia coli (E. coli) detection was improved@from 104 cells/mL to 102 cells/mL for 3 hours diagnosis time.

 

16pC-6 

Detection of Specific Sequences under a Fluorescence Microscope Using Homologous Recombination Protein

–Department of Mechanical Engineering, The University of Tokyo,––Genomic Sciences Center, RIKEN–––The Horizontal Medical Research Organization, Kyoto University––––School of Science and Engineering, Waseda University         

Yuji KIMURA*, Takashi KINEBUCHI**, Hiroyuki KABATA***, Hitoshi KURUMIZAKA**** and Masao WASHIZU*

Optical mapping is a powerful method to map target sequences on DNA and facilitates to order large insert clones covering a large DNA, such as the human genome. To expand applications of optical mapping, the RecA protein was utilized for locating sequences of interest. The RecA protein forms a functional complex with single-stranded DNA, binds to double-stranded DNA, and searches sequences on the DNA homologous to that of the single-stranded DNA. We combined sequence-probing function of RecA with a microelectrode system by which DNA is immobilized with a uniformly-stretched conformation of DNA molecules. This combination enabled us to visualize fluorescence-labeled DNA probes, which consisted of exonuclease-resected duplex DNA, bound along target DNA. From the analysis of the binding position of the DNA probes, we expect RecA can be used as a sequence-probing tool for optical mapping.

 

16pC-7 

Stretching and positioning of single stranded DNA as a template for molecular construction     

Department of Mechanical Engineering, The University of Tokyo       

Takuya Kobayashi, Masao Washizu

The high-specificity self-assembling nature of DNA makes the molecule a candidate for the template for the construction of molecular devices. In order to construct a functional device, the template must be positioned onto a predetermined site on a substrate to allow external connections, and the components must be properly aligned onto the template. A key factor is the high yield of binding, especially when the device consists of many components. Such high yield requires that the bases of the template DNA be exposed so that its counterpart can interact freely, and the template be stretched to avoid folding or coiling that hampers the interaction. For this purpose, we have developed a method, by which a single-stranded DNA is stretched and immobilized bridging over an electrode pair, with the molecular ends anchored while the middle part is left free to interact with foreign molecules. We expect that these stretch-and-positioned DNA with accessible base-pairs will lead to the high-yield molecular construction.

 

16pC-8 

Acquisition of DNA Fragments Using Laser Ablation

*Advance Co., ** BRAIN, ***The University of Tokyo, Department of Mechanical Engineering  

Osamu KUROSAWA*,**,*** and Masao WASHIZU***       

A novel method for the acquisition of DNA fragments from targeted position of DNA using laser ablation is presented in this paper. The developed device consists of two substrates facing each other, a) an ablation substrate, where an ablation layer, a DNA carrier layer, and a pair of electrodes are deposited onto a glass substrate, and b) a counter substrate. DNA first is stretched and aligned onto the ablation substrates by the electrostatic stretch-and-positioning method. When the ablation layer is irradiated with a focused laser, it explodes, and the DNA fragment together with a piece of carrier layer is blasted, to be recovered onto the counter substrate. The experimental demonstration is made with a spin-coated 10-200nm thickness silica layer as the carrier layer, and a 100nm thickness black pigment as the ablation layer. Using 1mJ pulsed YAG laser, acquisition onto the counter substrate of 1) a 1.7mm-diameter micro bead on 10 nm thickness carrier layer, 2) DNA adsorbed on a 8mm-diameter 200nm-thickness micro disc, are demonstrated. When the method is applied for the acquisition of fragments from stretch-and-positioned DNA on 10 nm thickness carrier layer, the ablation itself was successful, but no fragment was detected on the counter substrate. A possible interpretation for this is that the ablated particle was so small that it failed to reach to the counter substrate by inertia, especially when it is electrostatically charged during the ablation and pulled back to the ablation substrate. The use of thicker micro-patterned substrate, by which the whole mass is ablated together, is expected to solve the problem, and our current effort is focused in this direction.

 

16pC-9 

recovery of DNA molecules from agarose gel using @electrophoresis and electrolysis

Department of Ecological Engineering, Toyohashi University of Technology     

Jun Komatsu, Kazunori Takashima, Shinji Katsura, Akira Mizuno   

A manipulation technique of single-DNA molecule has been studied for genome analysis and observation of biological reactions at a single-molecule level. A manipulation of DNA molecules is difficult because long DNA molecules are very fragile in a solution. Especially, longer DNA molecules easily undergo fragmentation by convections of the solution. Although longer DNA molecules such as chromosomal DNA molecules are usually embedded in an agarose gel, called "gel-plug", to avoid such fragmentation, it is hard to handle the DNA molecules for biological experiments in a gel-plug. We proposed a recovery method of DNA molecules to a solution accompanied by a coil-globule transition. This method was based on electrophoresis and supplementation of cations which is necessary to globule-phase transition by electrolysis of aluminum electrodes.

 

16pC-10           

Development of Dielectrophoretic Filter for Viable-Nonviable Cell Separation

*Faculty of Engineering, Gunma University, **Masuda Research, Inc., ***Textile Research Institute of Gunma    

Masaru HAKODA*, Yoshikazu WAKIZAKA*, Shinichi MII**, Nobuyoshi KITAJIMA***, Naohiro SHIRAGAMI* 

In the large-scale cultivation of cells in a bioreactor, nonviable cells increase as time progresses. However, it is difficult to separate only the nonviable cells from the bioreactor. It is possible to discharge only the nonviable cells using a dielectrophoretic (DEP) filter; however, the separation efficiency is very low. In this paper, the separation efficiency of the novel DEP filter was examined. First, the electrical difference between viable cell and nonviable cell was clarified according to the single shell model. Using the wire-wire electrode was used as a model electrode of DEP-filter, the critical applied voltage which can be retained polystyrene standard particles by negative-DEP force in flow field was examined. The experimental value of the retention of particles followed the value of critical applied voltage deduced from relational equation of the ήE2 and the dielectrophoretic velocity. Furthermore, the particles were separated using the cross-flow DEP-filter, and operating conditions such as applied voltage and flow velocity were examined. The operating condition for retaining particles from the experimental value of the dielectrophoretic velocity was clarified.

 

16pC-11

Gunma@Univ.   

Toshiko KAI, Takayuki OSHIMA, Masayuki SATO

 

16aC-1 

Soot Incineration of Diesel Engine Exhaust Using Nonequilibrium Plasma     

Osaka Prefecture University        

Masaaki OKUBO, Naoki Arita, Tomoyuki KUROKI and Toshiaki YAMAMOTO          

In recent years, the air pollution and the influence to human of NOx and PM from diesel engine exhaust gas become severe problems. More effective post-processing technology is desired on PM, such as carbon soots. In the present study, a regeneration of DPF was performed using the low temperature atmospheric pressure nonequilibrium plasma. In the experiment with a diesel engine, the regeneration of DPF could be confirmed, and the regeneration temperature could be decreased from 600Ž to 300Ž.

           

16aC-2 

CO2 Reforming of Hydrocarbons with Nonthermal Plasma  

National Institute of Advanced Industrial Science and Technology     

Shigeru FUTAMURA and Annadurai GURUSAMY

CO2 reforming of methane, propane, and neopentane was investigated with a ferroelectric packed-bed reactor in N2 at different temperatures. No chemical interaction was observed between these hydrocarbons and CO2 in nonthermal plasma, and their conversions decreased with an increase in the counterpart hydrocarbon or CO2. H2 yield also decreased with an increase in CO2 concentration.  CO was formed both from CO2 and CH4, and its yield decreased with an increase in CH4 concentration. The molar ratio of H2 to CO depended on substrate hydrocarbon and reaction temperature, and decreased with increases in CO2 concentration and reactor energy density.  The reactivity of the hydrocarbon decreased in the order: propane > neopentane > methane.  With an increase in reaction temperature, hydrocarbon conversion and H2 yield increased.  Reaction temperature controls the subsequent and thermal processes of secondary decomposition of hydrocarbon and product formation, which are induced by radicals generated in situ         

 

16aC-3 

Fabrication and Application of Carbon Nanotube-based Gas@Sensor Using Dielectrophoresis 

Graduate School of Information Science and Electrical@Engineering, Kyushu University

Guangbin ZHOU, Hiroshi IMAKIIRE,Junya SUEHIRO and Masanori@HARA           

Carbon nanotubes (CNTs) have attracted much attention as a new class of@electronic materials because of their diameter of the order of nanometers@and their structurally sensitive electronic properties. In order to develop@an electronic device composed of CNTs, it is necessary to accurately@manipulate them to form a patterned array. In this study, a new fabrication@method of a gas sensor composed of multi-wall carbon nanotubes (MWCNTs)@using dielectrophoresis (DEP) was described. MWCNTs dispersed in ethanol@were trapped and enriched in an interdigitated microelectrode gap under@action of positive DEP force that drove MWCNTs to higher electric field@region. During trapping MWCNTs, the electrode impedance varied as the number@of MWCNTs bridging the electrode gap increased. After the DEP process, the@ethanol was evaporated and the microelectrode retaining the MWCNTs was@exposed to ammonia (NH3) or nitrogen dioxide (NO2) while the electrode@conductance was monitored. It was found that the electrode conductance was@altered by ppm-levels of NH3 as well as by sub-ppm level NO2 at room@temperature.

           

16aC-4 

Dielectrophoretic Fabrication of Carbon Nanotube-based NO2

Sensor and Sensitivity Control@Graduate School of Information Science and Electrical@Engineering, Kyushu University

Hiroshi IMAKIIRE, Guangbin ZHOU, Junya SUEHIRO and Masanori@HARA           

In our previous studies, it was demonstrated an electrokinetic fabrication@method of a carbon nanotube (CNT) gas sensor using dielectrophoresis. One@advantage of this method was that one could quantify the amount of trapped@CNTs on a real time basis by monitoring electrical impedance of the sensor@(dielectrophoretic impedance measurement, DEPIM). In the present study, we@extended the DEPIM technique and  controlled the amount of trapped CNTs.@This realized a production of CNT gas sensors with identical electrical@properties such as initial conductance. The gas sensor response to ppm-level@nitrogen dioxide (NO2) gas was investigated with various values of the@initial conductance. It was found that relative conductance change of the@CNT gas sensor after NO2 exposure increased almost proportionally with the@initial conductance for a constant NO2 concentration. This enabled to define@intrinsic sensitivity of CNT sensors by normalization. It was found that a@single-wall CNT gas sensor had higher normalized sensitivity than a@multi-wall CNT sensor.          

 

16aC-5 

Water Vapor Desorption and Adsorbent Regeneration Using Nonthermal Plasma

Department of Energy Systems Engineering, Osaka Prefecture University

Toshiaki YAMAMOTO, Goichi TANIOKA, Tomoyuki KUROKI and Masaaki OKUBO   

The dehumidification from a dehumidifier or an air conditioner was employed to achieve a comfortable and desirable indoor environment. Water vapor adsorbed on adsorbent needs to be regenerated when the water vapor exceeds the adsorption capacity. The conventional process for adsorbent regeneration or moisture desorption uses the heat by means of the heater. In the present study, the water vapor desorption from the adsorbent was investigated by using the nonthermal plasma for possible replacement of the electric heater. As a result, the water vapor desorption rate showed superior characteristics in term of energy efficiency. i.e. desorption per unit energy is significantly higher. At the same time, the gradient of water vapor desorption (desorption rate) is significantly higher or quick desorption can be achieved, which leads to more controllable and flexible air conditioning system.

 

16aC-6 

Effective Combination Methods for Useful Zeolites and Nonthermal Plasma Hybrid System in Toluene Decomposition    

National Institute of Advanced Industrial Science and Technology      S

eung-Min OH*, Hyun-Ha KIM*, Hisahiro EINAGA*, Atsushi OGATA*, Shigeru FUTAMURA*, and Dong-Wha PARK**    

Toluene was decomposed in a surface discharge plasma reactor and the combination effect of zeolite in the plasma reactor was studied. The reactor configuration and the adsorption capacity of zeolite for toluene influenced on the decomposition efficiency and product compositions. Product gas consisted of CO2, CO and HCOOH including some intermediates, which decomposed to COx in a temperature-programm ed desorption (TPD) and oxidation (TPO) reactor. The synergistic effect of zeolite was attributed to toluene adsorption and followed by oxidation on the zeolite with O3 derived from the plasma region. Adsorbed toluene on the zeolite was not properly decomposed in the head of plasma, while it was easily decomposed in the tail of plasma because oxygen species generated from plasma enhanced the toluene oxidation. With the increase of the decomposition efficiency, O3 concentration in the product gases was significantly reduced.           

 

16aC-7 

Surface Oxidation Process using an electron free negative ion generator         

National Institute of Advance Industrial Science and Technology (AIST)        

Masateru NISHIOKA

Strong, high purity and sustainable atomic oxygen radical anion (O?)@emission was observed from a synthesized microporous crystal 12CaO?@7Al2O3 (named C12A7) surface. The O- emission from the C12A7 has been applied to a surface oxidation treatment. A silicon wafer was used as@tested sample. In spite of low sample temperature (less than 350oC ) and high vacuum condition (less than 10-4Pa), the Si has been reacted to@SiO2 by O- irradiation. The surface roughness of O- oxidation Si was observed by AFM, there was not found significant difference between@thermal oxidation samples.        

 

16aC-8 

Numerical Simulation of CF4 Decomposition Using Low Pressure RF Plasma

Department of Energy Systems Engineering, Osaka Prefecture University      

Tomoyuki KUROKI, Shingo TANAKA, Masaaki OKUBO and Toshiaki YAMAMOTO   

Among perfluorocompounds (PFCs), we focused on CF4 used in semiconductor manufacturing process which was considered as one of the most difficult to decompose gas. We have been investigated the decomposition of CF4 using the inductively coupled plasma (ICP) reactor with RF power supply. This technology was confirmed to achieve a high efficiency and more economical system in comparison with the conventional system. Numerical simulation was carried out to obtain gas temperature, electron temperature and electron number density to cope with CF4 decomposition in the ICP reactor.

 

16pA-1

Characteristics of ""Elekiter"" (Electrostatic Generatior Restored Based on ""Erekiteru Zensho"" (Treatise on Electrostatic Generators)"    

Tottori@‚t‚Ž‚‰‚–D        

Ryo Nishimura, Katsumi Nishimori, Naganori Ishihara      

In 1770, Gennai Hiraga, a member of the Takamatsu clan born in Shidoura, Sanuki, Okawa-gun (a county of  Kagawa Prefecture) was given a broken machine called "Elekiter" which could generate static electricity by friction, belonging to a Dutch translator. He repaired the generator in 1776.  The Elekiter is believed to be the oldest electrical machine created in Japan.  In 1814, Tachu Kasamine described an inner structure and an example of the dimensions of the Elekiter.  In this research, aiming to investigate the characteristics of an Elekiter at that time, we restored an Elekiter referring to Tachu's discription without using synthetic resins.  The Elekiter was restored by using wood, metals, Japanese paper, silica glass and Japanese lacquer.  We measured the basic characteristics of the Elekiter.  The results showed that the generated potential was up to about 7 kV and the electrostatic voltage in the Leiden jar of the Elekiter decayed with the time constant depending on the generated voltage. 

 

16pA-2 

Frictional @Electrification and Corona Electrification of @Fibers   

Faculty of Textile Science and Technology, Shinshu University          

Masamichi NISHIZAWA, Isao NAKAMURA and Keiji OHARA        

An apparatus was constructed for simultaneous measurements of frictional electrification and corona electrification of filaments or fibers, and for estimating the electrification properties of fabrics from the electrification properties of fibers. As a preliminary experiment, nylon string was used, which was rubbed by PVC od. Nylon string was electrified positively as usually observed in triboelectric series of polymers. The magnitude of electrification voltage per unit length of strings was larger in the case of corona-electrification. As a result of analysis of variance, it was clear that the influence of the speed of fiber transfer on the  observed electrification voltage was effective.wever, the normal load has no effect on the electrification of nylon fiber.

 

16pA-3 

                                   

16pA-4

Tiny droplet formation on PDMS sheet by AC high electric field        

Department of Ecological Engineering, Toyohashi University of Technology     

Michihiko Nakano, Kazunori Takashima, Shinji Katsura, Akira Mizuno        

Small water droplets in oil were produced on dielectric film by AC high voltage. Electrodes of tungsten wire and aluminum tapes were covered with PDMS dielectric sheet. Water in oil emulsion was placed on PDMS sheet and AC high voltage was applied. When 5kVp was applied to the wire electrodes, large water droplets in oil were broken up to many tiny droplets, while they were moved toward to wire electrode due to dieletrophoretic force when the applied voltage below 3kVp. The size of the tiny droplets was approximately less than 10 m. After breaking up of water droplets, remaining droplets were placed in polygonal form under AC high electric field, which were not only pearl-chain but also triangle and square form.

 

16pA-5

The ion generation in the collision of the water jet

Department of Electrical and Electronic Engineering, Kanagawa Institute of Technology           

Hirofumi SHIMOKAWA  

It is known that the charged fog arises in the circumference of the water jet, when the water is ejected from the nozzle. Generation rate of the ion increases by the induction field. This report examined the ion which arose in the collision of the water. Next fact clarified as the result. (1)The reversely-polarized electrification fog arises on the polarity of the jet. (2)The electrification fog increases, as the impact angle increases, and as the impact speed increases. (3)The generation rate of the electrification fog is greatly dependent on the resistivity of the water, and the resistivity in which the electrification fog is minimized exists. (4)This phenomenon arises, when the water jet collides in the layer in the water on the metal. (5)For the generation of the reversely-polarized electrification fog, it is considered to originate from division of image electric charge induced on the water surface or division of the polarization charge on water droplet.

 

16pA-6 

Thermally stimulated current spectra of polypropylene heat-treated at high@temperatures.    

Keio University, Science University of Tokyo

Kazuo Ikezaki, Yuji Murata         

Thermally stimulated current (TSC) spectra were observed for polypropylene heat-treated at high temperatures.  The peak position and the half width of the high temperature TSC band  were examined in detail: With increasing treatment temperature, the peak position increased and the band width decreased till the treatment temperature of 150-155 C.   When the treatment temperature was raised to 160 C, then the peak position and the band width of the high temperature TSC band changed to decrease and increase, respectively.   These TSC results were discussed from a viewpoint of crystalline transition from alpha 1 to alpha 2 for polypropylene.

 

16pA-7 

Observation of flow electrification in dielectric liquid flows over metal walls   

Department of Mechanical Engineering, Faculty of Engineering, Okayama University  

Satoshi TAKAHASHI, Seiichi WASHIO, Hitoshi FUJIHARA           

In this paper, flow electrification between several kinds of metals and two kinds of dielectric liquids were measured. The electric current collected from a mesh increases with the flow rate and varies with the metal at the same flow rate. These results show that electric charges generated by flow electrification depend on the velocity at which liquid passes over the solid wall and also on the liquid-solid combination. Moreover, the charged oil passes through a mesh were relaxed in a low velocity, but as the velocity increase, the electric charges on the mesh by the electrification increase to the value of passing no-charged oil through it.

 

16pA-8 

Evaluation of the velocity of streamer in N2-O2 and SF6-N2 gas mixtures through Numerical Simulation Technique of Streamer Development       

Department of Electrical Engineering, The University of Tokyo         

Takashi Mizobuchi, Hiroyuki Toyota, Akiko Kumada, Kunihiko Hidaka         

Because the modeling of discharge phenomena is too complicate to understand completely the mechanism, the two approaches of experimental and theoretical studies are neccessary. Although numerical simulations are very useful for the theoretical study, they could sometimes be unstable or take too much time. In this paper, the discharge, especially the streamer discharge, in the N2-O2 and SF6-N2 gas mixtures is investigated by using the numerical simulation method.

 

16pA-9 

Influence of gas contents on negative air ion generation by corona@discharge

*Mitsubishi Electric Co.C**Faculty of Engineering, Tokyo UniversityC***National Institute of Advanced Industrial Science and Technology          

Koji OHTA*, Yasuhiro TANIMURA*, Masaki KUZUMOTO*, Shinobu USHIJIMA**, Masateru NISHIOKA***, Mitsuo YAMAMOTO** and Masayoshi  SADAKATA**        

Atmospheric negative air ions generated by corona discharge have been measured by atmospheric pressure ionized mass spectrometer (API-MS). Principal negative ions generated in ultra-pure air were O|, O2|, O3|, NO2|, NO3| ions. Adding water in the ultra-pure air, O2|En(H2O), O3| En(H2O), NO2|En(H2O), NO3|En(H2O) ions were detected in addition to the ions which detected in case of ultra-pure air. Adding carbon dioxide in ultra-pure air, CO3| ions was detected. But concentration of CO3| ions was not influenced by the concentration of carbon dioxide. In case of adding 4000ppm water vapor with mixture gas of ultra pure air and carbon dioxide, concentration of CO3|En(H2O) ions increased remarkably. It turned out that the role with water vapor was shown in formation of carbonic acid ions.

 

16pA-10

Design and trial production of the electrostatic field mill

Iwate University

Daishi HATANAKA, Shusuke TAKAHASI, Shoji KATO, Seiji MUKAIGAWA,Koichi TAKAKI, Tamiya FUJIWARA          

A mill type electric field meter has been constructed to measure the electric field change due to lightning discharge. Alternating voltage proportional to the field is produced by the mill consisted of two inductive electrodes and four rotary blades. The preliminary experiment was performed using a DC high voltage power supply. The results showed that the output voltage increased with applied electric field and rotary speed. The maximum sensitivity of electric field is about 50,000V/m without amplifier.

 

16pA-11           

Induction Charging of Droplets by Vibrating Orifice Aerosol Generator and Application to Electric Field Measurement     

*Hokkaido Inst. Techno., **Hokkaido Univ.

Takashi SATO*, Keiichi YAMAYA*, Yoji NAKAJIMA*         

A small parallel plane electrode is installed at the position of the outlet hole of the head cover of a vibrating orifice aerosol generator. A DC voltage is applied to it so as to induce electric charge on the tip of liquid jet ejected from the earthed micro orifice. The liquid jet breaks up to yield charged droplets. In the present experiment, the relationship between the droplet charge and the liquid concentration, and the effect of the length of liquid jet have been examined. The results are as follows;

(1)The amount of charge is independent of evaporation of volatile liquid.

(2)The induced charge increases with the length of liquid jet.

 We used high voltage insulated cable as a test piece for electric field measurement

 

16aE-1

A study on ESD induced magnetically instability of GMR head        

Hitachi Global Storage Technologies Japan, Ltd.    

Kouji KataokaCShoji Natori and Takayoshi Ohtsu            

ESD tester for GMR head (Giant magneto-resistive head) which has unique ESD waveform simulator, AC type QST (Quasi-Static Tester )  and Laser heat function was developed. In this paper, we studied the ESD damage of GMR head by the ESD waveform. Furthermore, we investigated the ESD induced magnetically instability phenomena of GMR head.

 

16aE-2 

Analysis of ESD Failure Mode in GMR Head by Using Spinstand     

*Hitachi, Ltd. **Hitachi Global Storage Technologies Co., Ltd

Takayuki ICHIHARA*, Takehiko HAMAGUCHI* and Takayoshi OHTSU**   

‚` new magnetic failure mode caused by ESD current was investigated using a spin-stand with a pre-amplifier with a built-in ESD simulator circuit. This failure mode originates in Barkhausen noise from unexpected domain walls in the free layer of a giant magnetoresistive (GMR) head. According to a modified machine model (0 ohm, 50 pF), this failure occurs at around 0.5 V, i.e., a quarter of that at which a conventional pinned layer reversal failure occurs.

 

16aE-3 

Characterization of ESD Control Material 

Kureha Chemical Industry Co., Ltd.

Naomitsu NISIHATA, Tatsuya KAWASAKI, Yuuichi KOMATSU       

New ESD control materials, based on combining special carbon material developed for the purpose of ESD control with PEEK (Polyetheretherketone), have been developed and assessed. The surface resistivity of the special carbon with resistivity of 107 ohms/sq., filled with PEEK, remained in the range of 108 to 109 ohms/sq. regardless of the carbon content beyond each critical range. The surface resistivity was easily controlled at the specific levels required for ESD control materials by using the special carbon. The surface resistivity fluctuation on the injection-molded plate was very small. The suitable surface resistivity range of ESD protection was estimated in the range of 108 to 109 ohms/sq. by the results of static decay time analysis and peak current analysis on ESD.

 

16aE-4 

Electrostatic Discharge from GMR Head in Magnetic Recording Tape System 

Advanced Tape Storage Development, Recording Media Company, Sony Corporation   

Yutaka SODA* and Hiroaki ONO 

A small sensor of a GMR head for magnetic recording is easily affected by electrostatic discharge(ESD). It was investigated that the GMR head in a helical-scan tape drive could be used in certain conditions of the tape surface resistance and the cassette material. Using the charged tape model increasing the tape surface resistance was effective in reducing the discharge current when the charge on the tape run through the GMR head.

The tribo-charge on the cassette made by rubbing the surface could induce the charge on the ME tape in the cassette. Using antistatic material for the cassette the charge on the tape was decreased less than the volume of the charge which can damage the GMR head

 

16aE-5 

The establishment of non-operation ESD test and the study of its damage mechanism for HDD

Hitachi Global Storage Technologies Japan, Ltd. 2.5"/1.8"CC BU, 1st design Dept.      

Tomohisa Okada

Electro-Static Discharge test widely uses as an electrical/magnetical evaluation test of component level like Giant Magneto-Resistive heads, head amplifers and read-write channels and it's damage mechanism is studied. On the other hand, ESD test performs as a reliability test of systems like mobile PCs, desk top PCs and so on. In order to understand system level ESD test, it is important to understand complex components like Head Stack Assemblys and Hard Disk Drives. But ESD test against complex components doesn't perform well. In this paper,ESD test evaluation method for HDD as the complex component was proposed and HDD's damage mechanism by ESD was studied.

 

16aE-6 

Electric characterristics of fluoric resin coared film reducing delamination charging of galass for LCD    

Kaijo corpration 

Akio FUJIE

There are many stages to put glass everywhere. The glass is pushed up by lift-up pins after being put on the stage, and having been@processed for such as vacuum absorption/ cooling or testing. At this time, Delamination charging with electricity happens to glass. I heard information that an overcoat of fluororesin is effective to restrain this delamination charging with electricity. I will report the result of measuring electric characteristics of the thin films and searching for some factors concerned with the reduction of the delamination charging with electricity on the glass.

 

16aE-7 

ESD Protections for Advanced Semiconductor Devices         

OKI Electric Industry Co., Ltd@SiSC(Silicon Solution Company) LSI Desighn Division

Yasuhiro Fukuda

Rapidly semiconductor device is developping to more integrated, high speed and low power device. This development is led by the innovations in telecominucation techniques, such as the cellular phone which is called "Keitai",  and other mobile equipments or terminals. On the other hand, it is realized the very integrated, high speed and low power semiconductor device by using new transistor structures, such as salicide or SOI transistor structures and separated power block designs. But generally these new technologies is weak to ESD (Electrostatic Discharge). This paper report ESD failure mechanism and protection design method for advanced semiconductor devices such as SOI devices.

 

16pE-1 

Characteristics of the conductive and dissipative implements which guard extremely sensitive devices against electrostatic discharge |The preventive measurement methods based on the excessive mobile charge|  

ESD Technical Department / Fab Solutions, Inc.     

Kouichi Suzuki, Naganori Takezawa, Michio Sato   

Conductive and dissipative implements are used to guard extremely sensitive devices against electrostatic discharge. The implements involve tweezers, device trays, mats on workbenches, carrier boxes of wafers, suction nozzles, UV sheets, garments and so on. Based on the excessive mobile charge theory, we developed the new measurement methods of IV characteristics and nano transient currents. Evaluation of implements with these methods showed that implements which carbon molecules are mixed into are characterized by the linearity, the resistance, the surface potential and the breakdown. Also, the suitable resistance of the conductive implements could be derived from the criteria of the excessive mobile charge. At present, almost all the implements cannot guard the extremely sensitive devices against the charged device model (CDM) and the stray capacitance model (SCM) events. However, the above study will give a clue to improve ESD safe material.

 

16pE-2 

Effect of Air Jet Rate on Static Elimination Characteristic of the Spot Jet Air Ionizer with jet emitter    

The Polytechnic University          

Hisayo YOSHIOKA, Nami TSURUTA and Kazuo OKANO   

An AC corona discharge air ionizer is one of the most useful equipment to eliminate static  charge on electronic devices in assembly processes. The inner jet air ionizer, which has a pipe-shaped emitter  to flow air in it, was proposed to increase the static elimination velocity. The static elimination velocity was  measured as a function of the air jet rate from the emitter. The elimination velocity of the inner jet air ionizer  depended on the flow rate and was 40 times higher than that of the non-jet air ionizer, when the ionizer was  operated with the biasing voltage of AC 16.0 kVP-P, 1 kHz, and 4.0 L/min of air jet rate.

 

16pE-3 

The High Frequency Corona Discharge Type Ionizer Suitable for the Measure of ESD Control against ESD Sensitive Device          

SHISHIDO@ELECTROSTATIC,LTD        

Wataru SHIMIZUCHidemi NAGATA, Kenkichi IZUMI       

High frequency corona discharge type ionizer shows the epoch-making characteristic that formed air ions can be transferred through the tube and the metal pipe. Positive and negative ions formed by high frequency corona discharge are mixed uniformly, so the electric attraction between the air ions and the grounded body is weakened and the neutralization rate of air ions on the wall of the body becomes lower. This ionizer gives the solution for ESD trouble in the local and detail position that is difficult to solute by means of the conventional ionizer. Also, it has the unique characteristic that the surface potential change for every slight unit time of the charged object placed in the air ion flow from this equipment can be held small, because positive and negative ions are generated once by 1/68000 seconds

 

16pE-4 

A Consideration about Ionizer Balance in HGA Process       

Quality Engineering Dept.,Wuxi ALPS Electronics Co.,Ltd. *Manufacturing Dept.2 Manufacturing Engineering Sect.2, ALPS Electric. Co.,Ltd., Magnetic Devices Division. **  

Sadao Kawata *, Takanori Nakajima **    

ESD robustness of GMR Head is decreasing along the increasing of areal   density.  Using ionizer is the one of the most popular way to prevent the   ESD damage. Ionizer balance in the HGA process is controlled less than 5V  by  using  CPM ( Charge Plate Monitor ), because it was reported that the  D-CDM ( Direct Charged Devices Model ) ESD robustness of 30Gb/in2 is less  than 5V. This value will continue decreasing from now on too. It is shown theoretically and experimentally in this study that the voltage of CPM is  very  different from the voltage on actual devices. It is understood from  this study that Ionizer is the Constant Charge Density Supplier. And the  voltage  on  actual  devices is defined by capacitance of that object. At  the  same  time,  we  got  the  formula which shows the voltage on actual  device  from  standard CPM. As result we got the following conclusion. It  is  no  use  controlling the Ionizer balance with the same voltage as the  voltage  of D-CDM robustness when suspension is grounded. And we can know  the real voltage value of actual devices.

 

16pE-5

Action for the electrical charge of Operator working on the Hard Disk Drive's Manufacturing Line

Advanced Technology Japan, HDI System Development       

Kazushi Tsuwako           

A GMR sensor is most sensitive part to ESD among the parts used in a hard disk drive. It's sensitivity is getting higher and higher year-by-year. Therefore GMR damage is main manufacturing yield detractor on the manufacturing line. It was found that most of all GMR sensor's ESD damage was occurred by the operator's electrical charge on our manufacturing process.

This paper introduces the activities to reduce the human body electrical charge of the operator working on the hard disk drive's manufacturing line. "

 

16pE-6             

Department of Electrical Engineering, Tokyo University of Science    

Takenori SAWAI, Takahiro YOSHIDA, Noriaki MASUI       

 

16pE-7

Effect of the Shape of Charged Metal on the Waveform of Discharge Current@Department of Electrical Engineering, Tokyo University of Science

Nobuhide KITAZUME and Noriaki MASUI           

By using hemispherical electrodes, the effects of the curvature of electrode on the short air gap discharge are investigated. Brass electrodes having different radii of curvature, r = 2.5 mm and 20 mm were used. Applied voltage is from +3 kV to +8 kV. Discharge occurs between high voltage electrode connected to the capacitor of 250 pF and the grounded electrode. Grounded electrode approaches the high voltage electrode at 0.4 mm/s and spark discharge is occurred. When the applied voltage is from +6 kV to +8 kV, peak current for r = 2.5 mm becomes lower than that for r = 20 mm. Peak current for both electrodes shows almost the same value, when the applied voltage is +3 kV.

 

17aB-1 

Improvement of Dielectric Barrier Discharge Type@Ozonizer by Electrode Shape

Iwate University

Masaki SHIMIZU, Shoji KATO, Seiji MUKAIGAWA, Koichi@TAKAKI, Tamiya FUJIWARA    

An effect of electrode shape on ozone generation in dielectricbarrier discharge reactor@is described in this article.@Three different shape electrodes were employed as ground electrodes.A plane electrode is 6 cm in width, and 20 cm in length.@A trench electrode has large number of knife-edge rails.@A multipoint electrode has large number of four-sided pyramid projections on the plane.@A high voltage plane electrode is covered with 0.5 mm thickness alumina layer worked as@dielectric barrier.@The experimental results show that the breakdown for the multipoint electrode occurs at@7.0 kVpp.@This value is lower than 8.4 kVpp that is breakdown voltage of the plane electrode.

 

17aB-2

Ozone Generation by Pulsed Power Generator using SOS Diodes       

Iwate University

Sadahide SAWADA, Shoji KATO, Seiji MUKAIGAWA, Koichi TAKAKI, Tamiya FUJIWARA    

Pulsed power generator using SOS (Semiconductor Opening Switches)  as a opening switches can make compact and lightweight and be driven   at high repetition rate.   We produced compact pulsed power generator using SOS diodes and  drove the co-axial type plasma reactor for ozone generation.  The co-axial cylinder plasma reactor consists of 1 mm diameter  tungsten wire and 19 mm i.d. copper tube with 30 cm length.  The gas mixture of N2:O2=9:1 was used as diesel engine exhaust gas.  The energy efficiency for ozone generation was obtained to 70 g/kWh  at 100 ppm in circuit at C=0.7 nF and L=2.5 ƒΚH.

 

17aB-3 

Observation of OH Radicals in Atmospheric Pressure Corona Discharge by Laser-Induced Fluorescence

* 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*, Atsushi Kajiwara, Jun-ichi Kumagai*, Hiroto Tanaka*, Toshikazu OHKUBO*, Yukiharu NOMOTO*, Marek Kocik**CJerzy Mizeraczyk**CJen-Shih Chang***      

The planar LIF detection of the hydroxyl (OH) radicals was performed in a nozzle-to-plane electrode system having an electrode gap of 30mm during the steady-state positive streamer corona discharge at atmospheric pressure. For monitoring the ground-state OH radicals, OH ( X2„P(vff=0)¨ A2ƒ°+(vf=1) ) transition at 282nm was used. Two-dimensional OH distribution in the DC corona discharge in air/H2O/Ar mixture was investigated. The obtained results showed that the ground-state OH radicals were observed in the filamentary part of the no branching streamer produced by Ar injection through the nozzle.

 

17aB-4 

Laser Induced Fluorescence Measurement of Atomic Oxygen Generated by a Pulse Barrier Discharge -Oxygen Concentration Effects-         

University of TokyoANational Institute of Advanced Indstrial Science and Technology

Kei TakezawaARyo OnoATetsuji Oda      

Laser Induced Fluorescence(LIF) measuring system was applied to the observation of atomic oxygen generated in a positive pulse barrier discharge under a high oxygen concentration condition. The electrode configuration is a metal needle to a plate of glass mounted on a ground plate.Oxygen density generated by a discharge and its reduction rate, oxygen z-scale distribution was not related to background oxygen concentration.The reduction rate at very close to the needle electrode was faster than one at other points.

 

17aB-5

Characteristics of Para‚Œ‚Œel Type Streamer Corona Discharger       

‚caikin Air-conditioning R&D Laboratory, Ltd.–ADepartment of Electrical and Electronic Engineering, Oita University––        

Kanji MOTEGI–AToshio TANAKA–AKenkichi KAGAWA–AToshikazu OHKUBO––       

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

 

17aB-6

Noise reduction of DC-streamer discharge caused by shortened gap   

Daikin Air-conditioning R&D Laboratory, Ltd.–ADepartment of Electrical and Electronic Engineering, Oita University––        

Toshio TANAKA–AKanji MOTEGI–AKenkichi KAGAWA–AToshikazu OHKUBO––       

One way to reduce the noise of DC-streamer discharge was investigated. The relationship with the gap length of the discharge electrodes and the@frequency of the discharge sound was indicated: the shorter the length is, the higher frequency becomes. The sound pressure level also reduced significantly at audible range. These results must be caused by one of the electrohydrodynamic effect of

streamer discharge. In streamer discharge, the ion drift may mainly affect the noise characteristics caused by the electrohydrodynamic effect. The time required for ion to traverse the electrode gap may be the important factor to determine the frequency of streamer discharge.

 

17pS-1                          Eiki Itaya

 

17pB-1 

The Influence of Fine Rectangular Grooves of Dielectric Barrier in SilentDischarge Plasma Reactor on NOx Treatment     

Department of Electrical Engineering and Electronics, Nippon Bunri University          

Toshiyuki Kawasaki, Tatsuya Okuda and Kunihiko Tanaka  "NOx treatment in a non-thermal plasma combined with catalysts, adsorbent and DPF, which lead to use porous ceramics, have been investigated experimentally.   In these cases, the surface fine structure of ceramics may play an important role for NOx treatment   In this study, NOx treatment characteristics are investigated using silent discharge plasma reactor equipped with the already fine processed ceramics.@In this paper, the Al2O3 plate with many rectangular grooves was used as a dielectric barrier in a silent discharge plasma reactor.   There were 30 rectangular grooves at the effective discharge area of 1600 mm2 (40mm~40mm) and the discharge gap length was 1mm. Discharge plasma was generated at the frequency of 1 kHz. A gas mixture of NO(200ppm) / N2 or NO(200ppm) / O2 (20%) / N2 were supplied into a plasma reactor at a flow rate of 1.0L/min from gas cylinders. As a result, the difference in NOx treatment characteristics between with and without rectangular grooves was observed.

 

17pB-2 

Application of micro-discharge in porous ceramics for NOX treatment

Department of Ecological Engineering, Toyohashi University of Technology     

Yoshihiko MATSUI, Jun SAWADA, Takahiro ITO, Kazunori TAKASHIMA, Shinji KATSURA, Akira MIZUNO    

Generation of transient discharge due to back-corona in dielectric porous materials was investigated for NOX removal. We expected that the application of the discharge generates many narrow micro-discharges inside and the surface of various ceramics materials. Four types of ceramics that have various perforation level (size of pores) have been tested using negative DC high voltage. The stable micro-discharge was formed with DC and AC high voltage and using ceramics average pores of 90 m and 15 m. As the results of NOX gas cleaning, oxidation ability without C2H4 addition was higher than that with additive at 20Ž.

 

17pB-3

Development of the detector for low energy scattered X-rays@using charged spheres

–Dept. of Ecological Engineering, Toyohashi University of Technology@––Technical R&D Center, Techno Ryowa Ltd"    

Masanori SUZUKI–ASeiiti IMAI––AHideaki MATSUHASHI––AAkira MIZUNO–       

Recently, in semiconductor and LCD manufacturing processes, ionizers have been used that employ low energy X-rays (soft X-rays) of 3 to 9.5 keV, as the ionization source. However, these low energy X-rays cannot be detected using film badges or the like as their energies are so low, and there is no appropriate personal dose meter. In these conditions, an inexpensive and easy-to-use personal dose detector is required for workers for daily use to avoid unexpected exposure.Therefore, we have designed a wearable low energy X-ray detector that uses four electrically charged conductive spheres floated by static electricity repulsion force.  Ions generated by ionization function of the low energy X-rays projected in the detector neutralize electrically charged conductive spheres. From the number of spheres dropped, the detector detects the dose of the low energy X-rays.@In this report, we have examined a simple way to detect low energy scattered X-ray dose from the number of dropped conductive spheres.

 

17pB-4 

Response Time of the Static Control System with Soft X-ray Air Jet Ionizer   

The Polytechnic University

Ryota HAGA, Kazuo OKANO      

The static control system with a photon air ionzer is proposed for manufacturing of a  semiconductor device. The control system has a control grid in the X-ray irradiated region. The response time  of the control system was investigated as a function of the biasing time and the biasing voltage. The response  time of the static control system depended strongly on the biasing time and the biasing voltage. It was clarified  that the static control system is available to shorten the settling time of the static elimination.

 

17pB-5 

Effect of gaseous atmospheres on particle generation from emitters for corona discharge ionize 

*Graduate School of Science and Engineering, Ibaraki University, **Department of Electrical and  Electronic Engineering, Ibaraki University@*** Department of Electrical Engineering, The Polytechnic University"

Hiroyuki IMAZONO*, Manabu TAKEUCHI** and Kazuo OKANO***

A corona discharge air ionizer is one of the most useful equipment to control electrostatic  charges in ULSI manufacturing processes. However, a corona discharge air ionizer generates particles that act  as contamination. Particle generation test was carried out for the silicon emitter and the tungsten emitter in  the air, the nitrogen and the argon atmospheres. The deterioration at the tip of the emitter was observed,  because the number of particle generation relates closely to the deterioration. The number of particle  generation from the silicon emitter was lower than that from the tungsten emitter for each atmosphere. The  number of particle generation in the argon and the nitrogen atmosphere was lower than that in the air  atmosphere. The number of particle generation for the silicon emitter in the nitrogen and the argon  atmosphere was about 200 times lower than that of the tungsten emitter in air atmosphere. Non-deterioration  was observed for the silicon emitter operated in the nitrogen and the argon atmosphere, while remarkable  deterioration was observed for the tungsten emitter operated in the air atmosphere.

 

17aC-1 

DEP liquid actuation in viscous fluid        

Toba National College of Maritime Technology*@The University of Tokyo** University of Rochester*** 

Tomohito Ito*AMasahide Gunji**AMasao Washizu**AT.B.Jones***          

The dielectrophoretic (DEP) force acting on a liquid provides a controllable means  for rapid movement and dispensing of small liquid volumes on a substrate. Microliter volume of water deposited on an insulating layer that covers  the coplanar electrodes forms a protrusion that runs along the electrode gap  when the voltage is applied, and is subdivided into small droplets when the voltage is turned off. It has been reported that the evaporation of water can be avoided by immersing the system into oil,  but no quantitative study has been made on the DEP motion in such a viscous medium. In this paper,  a two-dimensional model of the liquid protrusion motion is developed first,  taking into the viscous drag exerted by the viscous medium. Then experiments are conducted using silicone oil with various viscosities as the medium,  and the position of the protrusion front is measured as a function of time. Good agreements between the experimental and the calculated value are observed  when the medium viscosity is below 100 centi-Stokes. However, at higher medium viscosity, the speed was found to be smaller than that predicted by the theory. The discrepancy is attributable to the viscous force at the protrusion front, which is not included in the 2D model.

 

17aC-2

Basic Research on Disk Type Corona Motors ( ‡[)   

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

M. Hattori*, Y.Ringo*, M. Koizumi*, K. Takahashi,@T. Oizumi*, and K. Izumi**         

In our previous report, a disk-type corona motor using DVD (Digital Video Disk) type of rotor and discharging electrode type of stator was made and tested for the purpose of extension to a multi-disk-type corona motor. Generating torque of a corona motor depends on the number of discharging electrodes, however, the number of the electrodes was fixed at 16 poles in former experiments. This time, in order to decide an appropriate number of the discharging electrodes (stator), 16, 20 and 24 poles of electrodes with variable effective length were tested and the stator with 20 poles was evaluated as the best one for the effective air-gaps between stators and rotors. Moreover, the suitable shape of an easy-maintenance stator for multi-disk-type corona motor is proposed and an application of the corona motor to an ozonic water generation system with a small-sized centrifugal pump is also discussed.

 

17aC-3 

Preparation of WO3 thin films by pulsed laser deposition and their application to electrochromic devices (II)      

*Venture Business Laboratory, Oita UniversityC**Faculty of Engineering, Oita University     

Fumiaki MITSUGI*, Akihiro NAKAMURA**, Toshikazu OHKUBO** and Yukiharu NOMOTO**         

Electrochromic devices using tungsten trioxide WO3 films and ion (H+, Li+, Na+) conducting electrolytes have attracted much interest due to their superior characteristics such as no view angle dependence, low power consumption, memory effect and less stress for our eyes. In this work, the inorganic solid electrolyte of LiMn2O4 was used as an electrolyte in place of conventional liquid electrolytes. We have tried to prepare the inorganic solid electrolyte. The oxide solid state ITO(Indium tin oxide)/LiyWO3-x/LiMn2O4/ITO stacked structure was deposited on the silica glass substrate by pulsed laser deposition for its electrochromic application. ITO thin film prepared at room temperature and oxygen pressure of 5 Pa had relatively high conductivity and optical transmittance. The conductivity of amorphous LiMn2O4 thin film was quite low because of its large grain boundary. However, we found that the amorphous LiMn2O4 thin film was suitable for electrochromic devices. Blue colored electrochromic property of all oxide solid state film was realized by optimization of each film property. The transmittance at a wavelength of 750 nm for the stacked film changed from 50% to 80% by the applied voltage, while the transmittance at less than 450 nm did not change.

 

17aC-4 

An Estimation of Charge to Mass Ratio Q/M of Powder Particles Sprayed by Atomized Powder Coating System  

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

Mitsuru MATSUI*, Takashi TAKAHASHI** and Tsutomu ITO***    

Charge to mass ratio (Q/M) of powder particles that is one of the most important parameters to evaluate performance of electrostatic powder coating system is described.  Assuming that powder particles are charged at the maximum value limited with Pauthenier's formula, charge quantity of each particle have been calculated based on particle size distribution curve of paint powder.  Thus, the acquirable maximum value of Q/M has been estimated from the sum of the charge quantity of each particle, and 1.22 micro-coulombs per gram has been derived for a sample powder used in the experiment.

 

17aC-5

Electrostatic Elimination of Metallic Particles from Plastic Flakes   

Nara National College of Technology         

Takahiro ImanishiAHaruhisa Fujii          

It is necessary to make the behavior of metallic particles under electric field clear in order to remove them from mixed plastics in the development of high-efficiency electrostatic separators for material-recycle use. In this paper, we describe the analytical and experimental results of their behaviors under the electric field formed in a roll-type electrostatic separator.

 

17aC-6

CREATION OF LOW REFLECTANCE SURFACE BY ELECTROSTATIC FLOCKING 

Chiba Institute of Technology

Tsutomu Isaka,Shoichi Hasegawa, Shunsuke Terashima, Yasuo Sekii,Tomonao Hayashi          

In designing the equipments used in the space, the thermal design of apparatus is an important subject. One of the promising methods of creating surface with very low reflectance is making surface by electrostatic flocking. In the present research the possibility of creating surface by electrostatic flocking with carbon fiber pile was investigated. Using an experimental set up having a pair of metal electrode with 5cm gap spacingCexperiments of making flocked surface were performed. The measurement of reflectance of regular reflection against the infrared raysCas well as the reflectance of diffused reflection against ultraviolet and visible ray was performed on the created carbon fiber-flocked surface. The results of these measurements demonstrated that the electrostatic flocking using carbon fiber pile is of the most promising method of making a surface having very low reflectance.

 

17pA-1 

Behavior of Discharge Streamers in High-intensity Acoustic Wave Field

Nihon Univ.       

Tomoo NAKANETakeshi‚l‚h‚x‚y‚i‚h‚l‚`C@Tetsuro@‚n‚n‚s‚r‚t‚j‚`       

The authors clarified that the influence of high-intensity sound wave on an electrical discharge was due to both the vibration of the medium and the pressure difference in the discharge region. This report describes the influence of these two factors on discharge current waveforms. Also, it is made clear that the width of discharge part is determined by the sound intensity.

17pA-2

Field Induced Luminescence and Increase in Tree Initiation Voltage in LDPE with Additive of Polycyclic Compound

Faculty of education Chiba University      

Yoshiaki Yamano and Kouji Ishikura        

The field induced luminescence from PE material with additive of polycyclic compound was investigated to con-firm the effect of  -electron excitation upon the increase in tree inception voltage. It was previously found out that the addition of anthracene to LDPE increases the tree inception voltage up to approximately 4 times higher than that for LDPE without additive. The polycyclic compounds used in this study were naphthalene(Nf),  anthra-cene(An), 9,10 bromo-anthracene(br), tetracene(Tr) and pentacene(Pn). AC(50Hz) voltage below the tree inception was applied to a needle electrode inserted to a block of LDPE with the additive. The spectrum of the luminescence was measured using PMT with optical filter. The experimental results show that luminescence due to the excitation of  pai-electrons is detected in all of the materials with additives except for Pn.  This indicates that the excitation of  pai-electron is occurred even in the material with additive where the tree inception voltage is not remarkably increased. It was found by the observation with a metallurgical microscope that small crystals of An are deposited in hexagonal plane form and are dispersed in the material, which lead to the relaxation of electric field around the electrode tip. The other additives are deposited in acicular or filament-like form, which lead to the distortion of the field. It is considered that the increase in tree inception voltage by An addition mainly results from the morphology of the material and the hexagonal plane crystal of the deposited An in the material.

 

17pA-3

AC Corona Discharge Characteristics from a Metal Wire Particle on Insulating@Sheet

Faculty of Engineering, Yamagata University

Yusuke KUDOCToshiyuki SUGIMOTO, Yoshio HIGASHIYAMA

A particle stuck to the surface of polymer insulator could be a source of@corona discharge.  It is necessary to investigate corona discharge@characteristics occurring on the polymer insulator because the corona@discharge degrades insulation performance of polymer insulator.  In this@research, influence of relative humidity on AC corona discharge from a wire@metal particle placed on a silicone rubber sheet was investigated.  In lower@relative humidity, corona discharge tends to occur at lower applied voltage.@Corona onset voltage from a wire particle placed at the center between the@electrodes tends to be large with relative humidity.

 

17pA-4 

Mass spectrometry of ions generated by corona discharge in the atmosphere  

*Kochi National College of Technology, **Matsushita Electric Works, Ltd.      

Kenkichi NAGATO*, Takahiro MIYATA**, Yasunori MATSUI** and Toshiyuki YAMAUTI**     

Measurements of mass spectra for negative and positive ions generated by corona discharge in the air were made by using a Drift Tube Ion Mobility Spectrometer/Mass Spectrometer (DT-IMS/MS). The spectra of negative ions were characterized by the ion peaks of NO3-, NO3-(HNO3)n, and NO3-NO3, indicating that the corona discharge in the air produces HNO3 and NO3 molecules. In the positive ion mass spectra, two series of cluster ions H3O+(H2O)n and NH4+ (H2O)n were found as dominant ions. The transition from H3O+ ions to NH4+ ions was observed with the increase in water vapor concentration.

 

17pA-5 

Characteristics of Cascaded Arc Discharge Triggered by Spark Discharge       

Yamagata University

Toshiyuki SUGIMOTO, Shuta FUKATSU, Yoshio HIGASHIYAMA    

The plural arc discharges occurring in cascade connection have possibilities for new applications using its same electrical energy and effective heat transfer.  The characteristics of the two cascaded arc discharges occurring three electrode triggered by spark discharge have been investigated experimentally.  Pulsed high voltage was applied to the middle electrode placed in between the anode and the cathode to trigger the cascaded arc discharge.  The cascaded arc discharges occurred at the both sides of the middle electrode for the initial anode-cathode voltage above a definite value. The cascaded arc current, the current duration and the residual voltage significantly depend on the series resistance..

 

17aD-1 

Evaluation Methods of Electrostatic Hazards in Liquid Sprays        

National Institute of Industrial Safety      

A. Ohsawa

We have investigated three evaluation methods of electrostatic hazards of liquid sprays by comparing with the breakdown field in air. The first method uses a calculated field distribution obtained by a charge density distribution measured with a suction Faraday cage.  Second, a simple method using a field sensor attached on a grounded cylindrical cage is examined.  Also the electric field distribution is obtained from the distribution of the floating potential of a single probe.  The field distribution obtained by the method using the field sensor is comparable with the distribution by the suction Faraday cage.  The method using the suction Faraday cage may be usable as an evaluation method of electrostatic hazards caused by electrification in liquid sprays.  The method by the field sensor may also be effective as the first stage of the evaluation.  The single probe method, however, is inadequate for the risk evaluation because of overestimation.

 

17aD-2 

Improvement of Performance for Nozzle Type Electrostatic Eliminator by Providing Hot Airflow

*Physical Engineering Safety Research Division, National Institute of Industrial Safety,@**Kasuga Denki INC, ***Faculty of Science and Technology, Tokyo University of Science

Kwang-Seok Choi*Mizuki Yamaguma*, Tomofumi Mogami**, Teruo Suzuki** and Yuji Murata***       

In order to improve the eliminating performance of a nozzle type electrostatic eliminator, the effect of a hot airflow on the ion generation ability of a nozzle type eliminator is investigated experimentally. The pressure (0.1 Mpa to 0.3 Mpa) and the temperature (23oC to 60 oC) of the air were controlled. It was confirmed that the hot airflow had an effect on the performance on electrostatic eliminator; namely, the ion generation ability was increased depending on the temperature and pressure for air to the surrounding region of the electrode in eliminator. These results were attributed to the activation of the corona discharge by increasing of temperature and to the blowing off the suppression gas near the corona electrode by the airflow.

 

17aD-3

Control of Electrostatic charge by using Feedback Control type Ionizer@for Powder Handling Process(2)

–Kasuga Denki INC ––National Institute of Industrial Safety, Independent Administrative Institution –––Dept. Chem. Eng., Osaka Prefecture University      

Tomofumi MOGAMI–, Teruo SUZUKI–, Mizuki YAMAGUMA––CKwang-Seok Choi––and Satoru WATANO––– 

As one method to protect a dust explosion/fire due to electrostatic discharge (ESD) in powder-handling process, we have developed the feedback control type ionizer that can control the electrostatic charge of powder. We evaluated experimentally the current version of the feedback control type ionizer through the full size pneumatic powder transport facility including a cylindrical silo. The electric field strength in the loading pipe was measured with an electrostatic field sensor of the air blow type, which was attached to down side of the flange type ionizer at distance of 0.01 m. As the experiment results, it was confirmed that the feedback control type ionizer is effective for control the electrostatic charge of powder. Experimental details and results are presented in this paper."

 

17aD-4 

Passive-Type Electrostatic Eliminator for Pneumatic Powder Loading           

–National Institute of Industrial SafetyA––Kasuga Denki INC@–––Dept. Chem. Eng., Osaka Prefecture University

Tsutomu KODAMA–, Mizuki YAMAGUMA–, Teruo SUZUKI––, Tomofumi MOGAMI––@and Satoru WATANO–––         

In order to prevent a dust explosion caused by electrostatic discharges in a silo during loading of particulate products in a pneumatic transport system, we have newly developed the passive-type eliminator installed at the end of the loading pipe inside a silo. It consists of a short length of plastic pipe and nozzle-type ionizers mounted on it. Each ionizer is equipped with a grounded needle electrode within a nozzle. To make clear the charge elimination mechanism, several materials for the plastic pipe were tested by real-size experiments using polypropylene pellets. It was found from the experiments that PTFE for the pipe material was effective for reducing the static charge on the pellets.

 

17aD-5 

Development of Anti-Static gloves ––KURARAY@CO.LTD.@–MCOC

––Shinichi Yoshimoto––Hisao@Yoneda–Yoshiteru@Matsuo

The  purpose  of  this  study is to produce safer working gloves. Large amount of Static  electricity accumulate on working gloves made of synthetic fibers or natural fibers.  It  occasionally  causes  electrostatic hazards such as electric shocks or explosions.  So  far  conductive  thread is mixed into textile gloves but antistatic effect is not perfect.We  found  that working gloves made from man-made leather including conductive thread staple can prevent electric shock and spark.

 

17aD-6 

The dependence of concentration and energy on the explosion of highly concentrated ozone gasi‡Uj

–Iwatani International CorporationA––National Institute of Advanced Industrial Science and Technology(AIST)        

Sadaki Nakamura–AKoichi IZUMI–AMasaharu Nifuku––AKunihiko Koike–ASadashige Horiguchi––  

The explosion properties of ozone were investigated. When the pressure was reduced from 760Torr to 10Torr, the lower explosion limit of ozone in oxygen shifted from 11vol% to 60vol%. Minimum ignition energy was strongly dependent on ozone concentration, so that the minimum ignition energy of 12.4vol%-ozone was 16 times larger than that of 14.3vol%-ozone. However, the tip angle of discharge electrodes had no serious effect on minimum ignition energy for ozone explosion.

 

17aD-7 

Effect of gap length on electrostatic discharge sensitivity     

* National Institute of Advanced Industrial Science and Technology , Faculty of Engineering, Kyusyu Sangyo University**

Eishi KURODA*, Toshiyuki NAGAISHI**,Yoshio NAKAYAMA*, Masatake YOSHIDA* and Syuzo HUJIWARA*            

In the ignition sensitivity test by electrostatic discharges, there are many parameters affecting on ignition of powdered materials. Series resistance and condenser capacitance were related to electric characteristics like discharge current, discharge resistance and discharge energy of electrostatic discharge. However, gap length had no effect on electric characteristics. The effect of gap length on the discharge characteristics has not yet been cleared. This report is aimed to clarify its effect by analyzing discharge sound. We carried out the measurements of discharge sound using electrostatic sensitivity tester under the wide range of conditions including favorable condition for ignition.  Amplitudes of discharge sound were more dependent on gap length and condenser charge voltage or initial voltage of discharge than on series resistance, condenser capacitance or discharge current.  The longer the gap length, the higher the amplitude, when gap length was ranging from 0.05 to 4.0mm as customary tested.  This was attributed to strengthening of pressure waves formed due to temperature rise in a discharge path, though longer gap length caused smaller diameter of a discharge path.@It is suggested that ignition sensitivity by electrostatic discharges for powdered materials is strongly dependent on the pressure waves formed, the temperature and the diameter of a discharge path.

 

17aD-8 

Electric ignition sensitivity of powders of dangerous article by probe plate test

* National Institute of Advanced Industrial Science and Technology , Faculty of Engineering, Kyusyu Sangyo University**

Eishi KURODA*, Toshiyuki NAGAISHI**,Yoshio NAKAYAMA*, Masatake YOSHIDA* and Syuzo HUJIWARA*

The probe plate method is to test whether a sample was ignited or not when it is rubbed on the metal plate with the metal probe under the applied voltage. It is one kind of the ignition tests by electrostatic discharges.  In this report, the ignition test of Zr, Zr-Ni(7:3), Zr-Ni(3:7), Pb(SCN)2/KClO4 and various picrates was carried out by the probe plate method.  It is observed that Zr, Zr-Ni(7:3), Pb(SCN)2/KClO4 were easier to ignite with very low energy under the small capacitance than metal powders such as Al, Ti and Mg.  It was thought that some picrates and the Pb(SCN)2 compounds ignited by the mechanism that was not the gaseous discharge.

 

17pD-1 

Electrostatic Discharge Problem Related With the Hydrogen Station

*School of Engineering, the University of Tokyo **National Institute of Advanced Industrial Science and Technology

Tetsuji Oda*, Tadashi Takahashi* and Ryo Ono**

For the population of the fuel cell driven automobile, the construction of the hydrogen station network is a necessary social demand.   At the same time, the electrostatic safety problem is not yet discussed.  The authors start to consider the electrostatic problems related with that hydrogen station in Japan.  This paper describes that first consideration and preliminary test report.

 

17pD-2

Gas Temperature of Spark Discharge in the Air      

National Institute of Advanced Industrial Science and Technology (AIST), The University of Tokyo         

Ryo ONO, Masaharu NIFUKU, Shuzo FUJIWARA, Sadashige HORIGUCHI, Tetsuji ODA       

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

 

17pD-3 

Explosibility of Polyurethane Dust           

*Research Center for Explosion Safety, National Institute of Advanced Industrial Science and Technology **Matsushita Refrigeration Company

Masaharu NIFUKU*, Hiroshi TSUJITA**, Kenji FUJINO**, Kenji TAKAICHI**, Cyrille BARRE*, Makiko HATORI*, Shuzo FUJIWARA, Sadashige HORIGUCHI* and Elsa PAYA*  

For recycling and saving resources, explosibility of polyurethane was studied. Polyurethane is used widely as insulating material for refrigerator. The polyurethane is foamed by cyclopentane, replacing chlorofluorocarbon in recent years, and explosive environment is produced in the recycling process of refrigerator. Explosion probability, minimum explosive concentration, autoignition temperature of the dust cloud, influence of inflammable gas (cyclopentane) on the explosibility of polyurethane dust, influence of relative humidity on the dust explosion, effect of reducing oxygen concentration on the dust explosion, etc. were studied. The minimum explosive concentration is about 40 g/m3, the autoignition temperature is around 500 oC, the explosibilty for the dust explosion increases when the cyclopentane gas exists jointly with the polyurethane dusts, the explosibility of the dust cloud decreases with the increase of relative humidity and the dust explosion is suppressed when oxygen concentration is reduced below 12 %.

 

17pD-4 

Measures for Elimination of Static Electricity from Customers at@Self-Service Gas Stations (‡T)         

Fire Science Laboratories, Tokyo Fire Department  

Makoto EGUCH and Kenji SUZUKI         

A number of fires, which are considered to have been caused by static electricity, occur in self-service gas stations.  We studied on the factors and countermeasures of those fires, by analyzing the actual fire incidents and investigating the cars involved in the fire. The major results were as follows:

1. The fires started 1) when the customer opened the cap of the car gastank, 2) when he/she stopped refueling to do other work, returned and touched the nozzle again, and 3) when he/she extracted the nozzle from the tank opening during or after refueling. 2. When the car involved in the fire was examined, non-grounded conductors were observed around the tank opening."

 

17pD-5 

Measures for Elimination of Static Electricity from Customers at Self-Service Gas Stations (‡U)           

Fire Science Laboratories, Tokyo Fire Department  

Kenji SUZUKI and Makoto EGUCHI

In our previous report, we analyzed static electric fire incidents and investigated the cars involved in order to make a close examination of the fires.  In this report we investigated the fire-causing factors and countermeasures by measuring electrostatic potential gradation of the human body at refueling work.  The major results were as follows:

1. Even when relative humidity is high, a fire may occur if a customer walks directly to the tank opening of the car after getting off, and opens the cap.2. Relaxation time of electric potential differs greatly depending on the shoes the customer is wearing.