Senichi Masuda

Control of NO/sub x/ by positive and negative pulsed corona discharges

The pulse-induced plasma chemical process (PPCP) is a novel means of processing with great potential in various applications including the removal of NO, SO/sub 2/, HCl, and Hg vapor and other gaseous pollutants from combustion gases, the composition of gaseous and solid substances, the production of ultrafine particulate materials, the treatment of surfaces, etc. An investigation of the DENOX and DESOX of combustion gas by PPCP was conducted, confirming that DENOX is possible by both positive and negative pulsings and DESOX only by positive pulsing. NO is oxidized by PPCP to NO/sub 2/, which is removed again by PPCP. The reaction speed for PPCP with positive pulsing is more than one order of magnitude higher than that with negative pulsing applicable to electrostatic precipitators. The reaction speed is greatly enhanced by raising the peak field intensity, which requires the use of a very sharp pulses. The speed is also enhanced by raising pulse frequency, lowering the gas temperature, and using sharp corona wires. The oxidation of NO and removal of NO/sub 2/ can proceed without O/sub 2/ and moisture, but is greatly enhanced by them. The addition of NH/sub 3/ also enhances NO/sub 2/ removal, possibly by its NO/sub 2/-scavenging effect from the gas phase, while it does not enhance NO oxidation. The combination of PPCP with the electron-beam DENOX and DESOX does not produce a nonlinear enhancing effect beyond the independent effect of PPCP alone. >

Novel method of cell fusion in field constriction area in fluid integration circuit

A novel method of cell fusion is developed based on the fluid integrated circuit (FIC) concept, in which all cell-handling components are photolithographically integrated on the substrate. A strong field constriction area is produced between the cell fusion electrodes by constricting all electric fluxes to a small opening made at the center of an insulating barrier placed between the electrodes. Cells are sent, one by one, from two micropumps, each containing a suspension of one type of cells, and then dielectrophoretically trapped at the opening to form a pearl-chain pair. Then the pulse voltage is applied to trigger the fusion of the cell pair. This procedure ensures that the fusion product is an exclusive one-to-one hybrid among the two species. Problems associated with the adhesion of the fusion product on the electrodes do not arise. The small dimensions of the field constriction area allow the application of constant pulse voltage on the cell membranes, regardless of the cell diameter. The FIC cell fusion device has been constructed and its performance tested. Analysis of the field constriction area is also made. >

A ceramic-based ozonizer using high-frequency discharge

A thin ceramic layer, either cylindrical or planar in form, is sandwiched by a number of parallel strip-like discharge electrodes and a film-like induction electrode. An AC exciting voltage of frequency 10 kHz and 10 kV peak-to-peak (p-p) is applied between the electrodes to produce a stable high-frequency surface glow discharge for generation of ozone. As a result of its high frequency, low exciting voltage, and small size, a great reduction in cost is achieved in both the ozonizer and its power supply. The presented ozonizer can easily produce a very high ozone concentration (5000-15000 volume p.p.m. for air; 50-100000 volume p.p.m. for oxygen) without using a special enrichment means. Its power efficiency can be made very high (170 gO/kWh for air) by proper selection of operating parameters. >

Decomposition of gaseous organic contaminants by surface discharge induced plasma chemical processing-SPCP

The decomposition performance of the surface induced plasma chemical processing (SPCP) for chlorofluorocarbon (83 ppm CFC-113 in air), acetone, trichloroethylene, and isopropylalcohol was experimentally examined. In every case, very high decomposition performance, more than 90 or 99% removal rate, is realized when the residence time is about 1 second and the input electric power for a 16 cm/sup 3/ reactor is about 10 W. Acetone is the most stable compound and alcohol is most easily decomposed. The decomposed product-analysis by a gaschromato-massspectrometer has just started but very poor results are obtained. In fact, some portion of the isopropylalcohol may change to acetone which is worse than alcohol. The necessary energy to decompose one mol gas diluted in the air is calculated from the experiments. The necessary energy level for acetone and trichloroethylene is about one-tenth or one-fiftieth of that for chlorofluorocarbon.

Handling biological cells using a fluid integrated circuit

Studies are made on the methods of cell handling using dielectrophoretic (DEP) force in a newly developed device called a fluid integrated circuit (FIC), where all cell-handling components are integrated into one substrate with photolithography techniques. Cell passages and driving electrodes can be fabricated in arbitrary two-dimensional shape, allowing great flexibility in design. Through analytical study, it was found that a careful tailoring of field pattern is essential in realizing cell motions. Methods for detailed field analysis were worked out, and based on the analysis, cell handling components were developed. One is an FIC cell shift register, a device in which cells are stored and electrostatically transported one by one, just as bits are shifted in digital-logic shift registers. The other is an FIC cell deflector, where a cell fed from the inlet can be dielectrophoretically deflected to either of the bifurcating branches. The devices have been fabricated and their functions were experimentally confirmed. >

Decomposition of fluorocarbon gaseous contaminants by surface discharge induced plasma chemical processing

Surface discharge induced plasma chemical processing (SPCP) using a high-grade alumina-based cylindrical reactor with an embedded ground electrode and stripe-shaped surface metal electrodes was applied to decompose chlorofluorocarbon contaminants in air, nitrogen, and oxygen. A very high decomposition rate, more than 99%, was observed for 100 or 1000 p.p.m. CFC-113. Greater electric power is found to be necessary to decompose the chemically stable fluorocarbon, but a substantial further improvement of efficiency will be possible in the near future. The authors feel that this system will be effective to decompose dilute fluorocarbon in large quantities.<<ETX>>

Separation of Small Particles Suspended in Liquid by Nonuniform Traveling Field

A study of size and charge-dependent separation of small particles in liquid using a traveling-field-type electric curtain device is made. The principle of the separation is to make use of the spatial harmonic components of the rotating traveling field produced by such a device, the first harmonic propagating in one direction, which plays a dominant role in the region distant from the electrodes, and the second harmonic propagating in the opposite direction, which becomes dominant near the electrodes. Small particles brought into this field undergo circular motion and, as a result of field nonuniformity, are repelled from the electrodes and drift in the direction of the dominant harmonics. The lighter or more charged particles are strongly repelled from the electrodes and swept by the first harmonic, while the heavier or less charged particles can approach the electrodes and are transported by the second harmonic in the opposite direction, thus enabling separation by mass and charge. First a theoretical investigation of this method is made to clarify the operation conditions for the separation, then the experimental observations of particle motion are made and scaling laws of transport velocity with the applied voltage and frequency are confirmed. Finally, an example of a cell separator design using this method is presented.

Initiation condition and mode of back discharge

Abstract Modes of back discharge occuring in the electrostatic precipitator were studied using, instead of a dust layer, the model samples of glass and mica plates with a pinhole, and tissue papers. It was confirmed that back discharge started to occur when the apparent field strength in the sample layers exceeded its breakdown field strength. Back discharge became a streamer corona under atmospheric conditions. It could be classified into a space streamer mode, a surface streamer mode and a mixed streamer mode, depending upon the field distribution around the breakdown point in the sample layers. The first and the third modes occurred when the field strength in the air gap, E a , exceeded about 5 kV/cm, and positive ions were generated in the whole gas space. The second mode appeared when E a was lower than about 5 kV/cm, and ion generation was limited to the near surface region. Among the factors affecting the back discharge, dust resistivity was the most important. For low dust resistivity, space streamers tended to develop from the breakdown points when the applied voltage was raised. For high dust resistivity, on the other hand, the number of breakdown points increased, and surface discharge was pronounced. A remarkable difference in modes was observed when using positive corona. Neither space streamer nor surface discharge occurred and the flashover voltage was higher than that with negative corona.

Ionic charging of a very high resistivity spherical particle

Abstract The total charge on a spherical insulating particle imparted by ion bombardment and its increase with time as well as its saturation value are derived. The results show that the saturation charge is considerably smaller than that calculated by Pautheniers equation. For instance, only 35% of Pautheniers limit is imparted to the particles having a specific dielectric constant ϵs=2. An experiment is made to verify the calculated results, and a good agreement within the error of experiment is obtained.

Low temperature atmospheric pressure discharge plasma processing for volatile organic compounds

Abstract The 1,000 ppm VOCs (volatile organic compounds) decomposition performance of SPCP (Surfaced Discharge Induced Plasma Chemical Processing) was studied relating to various carrier gas effects, plasma exposing methods and others in order to understand the decomposition mechanisms. In any carrier gas, a direct SPCP can decompose every VOC tested. The efficient decomposing carrier gases are oxygen, air and nitrogen in that order. However, when the SPCP treated gasses (air, nitrogen or oxygen) are mixed with contaminated gasses, oxygen seems be necessary to decompose VOCs. Four new halogenated (chloro-)organic materials are also tested as contaminants. The maximum decomposition for every contaminants is found to be more than 90% and the energy efficiency for each contaminant is roughly in the same order.