Showing papers on "Electric discharge published in 2004"

Plasma physics and engineering

Abstract: PART 1. FUNDAMENTALS OF PLASMA PHYSICS AND PLASMA CHEMISTRY. CHAPTER 1. Introduction CHAPTER 2. ELEMENTARY PROCESSES OF CHARGED SPECIES IN PLASMA. 2.1. Elementary Charged Particles In Plasma, And Their Elastic And Inelastic Collisions. 2.2. Ionization Processes. 2.3. Mechanisms Of Electron Losses: The Electron-Ion Recombination. 2.4. The Electron Losses Due To Formation Of Negative Ions: Electron Attachment And Detachment Processes. 2.5. The Ion-Ion Recombination Processes. 2.6. The Ion-Molecular Reactions. 2.7. Problems and Concept Questions. CHAPTER 3. ELEMENTARY PROCESSES OF EXCITED MOLECULES AND ATOMS IN PLASMA. 3.1. Electronically Excited Atoms And Molecules In Plasma. 3.2. Vibrationally And Rotationally Excited Molecules. 3.3. Elementary Processes Of Vibrational, Rotational And Electronic Excitation Of Molecules In Plasma. 3.4. Vibrational (VT) Relaxation, Landau-Teller Formula. 3.5. Vibrational Energy Transfer Between Molecules, VV-Relaxation Processes. 3.6. Processes Of Rotational And Electronic Relaxation Of Excited Molecules. 3.7. Elementary Chemical Reactions Of Excited Molecules, Fridman - Macheret a-Model. 3.8. Problems and Concept Questions. CHAPTER 4. PLASMA STATISTICS AND KINETICS OF CHARGED PARTICLES. 4.1. Statistics And Thermodynamics Of Equilibrium And Non-Equilibrium Plasmas, The Boltzmann, Saha And Treanor Distributions. 4.2. The Boltzmann And Fokker-Planck Kinetic Equations, Electron Energy Distribution Functions. 4.3. Electric And Thermal Conductivity In Plasma, Diffusion Of Charged Particles. 4.4. Breakdown Phenomena: The Townsend And Spark Mechanisms, Avalanches, Streamers And Leaders. 4.5. Steady-State Regimes Of Non-Equilibrium Electric Discharges. 4.6. Problems and Concept Questions. CHAPTER 5. KINETICS OF EXCITED PARTICLES IN PLASMA. 5.1.Vibrational Distribution Functions In Non-Equilibrium Plasma, The Fokker-Planck Kinetic Equation. 5.2. Non-Equilibrium Vibrational Kinetics: eV-Processes, Polyatomic Molecules, Non-Steady-State Regimes. 5.3. Macrokinetics Of Chemical Reactions And Relaxation Of Vibrationally Excited Molecules. 5.4. Vibrational Kinetics In Gas Mixtures, Isotopic Effect In Plasma Chemistry. 5.5. Kinetics Of Electronically And Rotationally Excited States, Non-Equilibrium Translational Distributions, Relaxation And Reactions Of Hot Atoms In Plasma. 5.6. Energy Efficiency, Energy Balance And Macrokinetics Of Plasma-Chemical Processes. 5.7. Energy Efficiency Of Quasi-Equilibrium Plasma-Chemical Systems, Absolute, Ideal And Super-Ideal Quenching. 5.8. Problems and Concept Questions. CHAPTER 6. ELECTROSTATICS, ELECTRODYNAMICS AND FLUID MECHANICS OF PLASMA. 6.1. Electrostatic Plasma Phenomena: Debye-Radius And Sheaths, Plasma Oscillations And Plasma Frequency. 6.2. Magneto-Hydrodynamics Of Plasma. 6.3. Instabilities Of Low Temperature Plasma. 6.4. Non-Thermal Plasma Fluid Mechanics In Fast Subsonic And Supersonic Flows. 6.5. Electrostatic, Magneto-Hydrodynamic And Acoustic Waves In Plasma. 6.6. Propagation Of Electro-Magnetic Waves In Plasma. 6.7. Emission And Absorption Of Radiation In Plasma, Continuous Spectrum. 6.8. Spectral Line Radiation In Plasma. 6.9. Non-Linear Phenomena In Plasma. 6.10. Problems and Concept Questions. PART 2. PHYSICS AND ENGINEERING OF ELECTRIC DISCHARGES. CHAPTER 7. GLOW DISCHARGE. 7.1. Structure And Physical Parameters Of Glow Discharge Plasma. Current-Voltage Characteristics, Comparison Of Glow And Dark Discharges. 7.2. Cathode And Anode Layers Of A Glow Discharge. 7.3. Positive Column Of Glow Discharge. 7.4. Glow Discharge Instabilities. 7.5. Different Specific Glow Discharge Plasma Sources. 7.6. Problems and Concept Questions. CHAPTER 8. ARC DISCHARGES. 8.1. Physical Features, Types, Parameters And Current-Voltage Characteristics Of Arc Discharges. 8.2. Mechanisms Of Electron Emission From Cathode. 8.3. Cathode And Anode Layers In Arc Discharges. 8.4. Positive Column Of Arc Discharges. 8.5. Different Configurations Of Arc Discharges. 8.6. Gliding Arc Discharge. 8.7. Problems and Concept Questions. CHAPTER 9. NON-EQUILIBRIUM COLD ATMOSPHERIC PRESSURE PLASMAS: CORONA, DIELECTRIC BARRIER AND SPARK DISCHARGES. 9.1. The Continuous Corona Discharge. 9.2. The Pulsed Corona Discharge. 9.3. Dielectric-Barrier Discharge. 9.4. Spark Discharges. 9.5. Problems and Concept Questions. CHAPTER 10. PLASMA CREATED IN HIGH FREQUENCY ELECTROMAGNETIC FIELDS: RADIO-FREQUENCY (RF), MICROWAVE AND OPTICAL DISCHARGES. 10.1. Radio-Frequency (RF) Discharges At High Pressures, Inductively Coupled Thermal RF Discharges. 10.2. Thermal Plasma Generation In Microwave And Optical Discharges. 10.3. Non-Equilibrium Radio-Frequency (RF) Discharges, General Features Of Non-Thermal Capacitively-Coupled (CCP) Discharges. 10.4. Non-Thermal Capacitively-Coupled (CCP) Discharges Of Moderate Pressure. 10.5. Low Pressure Capacitively-Coupled RF Discharges. 10.6. Asymmetric, Magnetron And Other Special Forms Of Low Pressure Capacitive RF-Discharges. 10.7. Non-Thermal Inductively-Coupled (ICP) Discharges. 10.8. Non-Thermal Low-Pressure Microwave And Other Wave-Heated Discharges. 10.9. Non-Equilibrium Microwave Discharges Of Moderate-Pressure. 10.10. Problems and Concept Questions. CHAPTER 11. DISCHARGES IN AEROSOLS, DUSTY PLASMAS. 11.1. Photo-Ionization Of Aerosols. 11.2.Thermal Ionization Of Aerosols. 11.3. Electric Breakdown Of Aerosols. 11.4. Steady-State Dc Electric Discharge In Heterogeneous Medium. 11.5. Dusty Plasma Formation, Evolution Of Nano-Particles In Plasma. 11.6. Critical Phenomena In Dusty Plasma Kinetics. 11.7. Non-Equilibrium Clusterization In Centrifugal Field. 11.8. Dusty Plasma Structures: Phase Transitions, Coulomb Crystals, Special Oscillations. 11.9. Problems and Concept Questions. CHAPTER 12. ELECTRON BEAM PLASMAS. 12.1.Generation And Properties Of Electron-Beam Plasmas. 12.2. Kinetics Of Degradation Processes, Degradation Spectrum. 12.3. Plasma-Beam Discharge. 12.4. Non-Equilibrium High-Pressure Discharges Sustained By High-Energy Electron Beams. 12.5. Plasma In Tracks Of Nuclear Fission Fragments, Plasma Radiolysis. 12.6. Dusty Plasma Generation By A Relativistic Electron Beam. 12.7. Problems and Concept Questions.

Hydrogen peroxide and ozone formation in hybrid gas-liquid electrical discharge Reactors

Abstract: Ozone in the gas phase and hydrogen peroxide in the liquid phase were simultaneously formed in hybrid electrical discharge reactors, known as the hybrid-series and hybrid-parallel reactors, which utilize both gas phase nonthermal plasma formed above the water surface and direct liquid phase corona-like discharge in the water. In the series configuration the high voltage needle-point electrode is submerged and the ground electrode is placed in the gas phase above the water surface. The parallel configuration employs a high voltage electrode in the gas phase and a high voltage needle-point electrode in the liquid phase with the ground electrode placed at the gas-liquid interface. In both hybrid reactors the gas phase concentration of ozone reached a power-dependent steady state, whereas the hybrid-parallel reactor produced a substantially larger amount of ozone than the hybrid series. Hydrogen peroxide was produced in both hybrid reactors at a similar rate to that of a single-phase liquid electrical discharge reactor. The resulting concentration of H/sub 2/O/sub 2/ in the hybrid reactors, however, depended on the pH of the solution and the gas phase ozone concentration since H/sub 2/O/sub 2/ was decomposed by dissolved ozone at high pH.

Power consideration in the pulsed dielectric barrier discharge at atmospheric pressure

Abstract: Nonequilibrium, atmospheric pressure discharges are rapidly becoming an important technological component in material processing applications. Amongst their attractive features is the ability to achieve enhanced gas phase chemistry without the need for elevated gas temperatures. To further enhance the plasma chemistry, pulsed operation with pulse widths in the nanoseconds range has been suggested. We report on a specially designed, dielectric barrier discharge based diffuse pulsed discharge and its electrical characteristics. Two current pulses corresponding to two consecutive discharges are generated per voltage pulse. The second discharge, which occurs at the falling edge of the voltage pulse, is induced by the charges stored on the electrode dielectric during the initial discharge. Therefore, the power supplied to ignite the first discharge is partly stored to later ignite a second discharge when the applied voltage decays. This process ultimately leads to a much improved power transfer to the plasma.

Measurement of positive gain on the 1315nm transition of atomic iodine pumped by O2(a1Δ) produced in an electric discharge

Abstract: Laser action at 1315nm on the I(P1∕22)→I(P3∕22) transition of atomic iodine is conventionally obtained by a near-resonant energy transfer from O2(a1Δ), which is produced using wet-solution chemistry. The system difficulties of chemically producing O2(a1Δ) has motivated investigations into gas phase methods to produce O2(a1Δ) using low-pressure electric discharges. In this letter we report on positive gain on the 1315nm transition of atomic iodine where the O2(a1Δ) was produced in a flowing electric discharge. The electric discharge was followed by a continuously flowing supersonic cavity that was necessary to lower the temperature of the flow and shift the equilibrium of atomic iodine more in favor of the I(P1∕22) state. A tunable diode laser system capable of scanning the entire line shape of the (3,4) hyperfine transition of iodine provided the measurements of gain.

Hybrid Gas-Liquid Electrical Discharge Reactors for Organic Compound Degradation

Abstract: A gas−liquid hybrid pulsed corona discharge reactor that utilizes high voltage needle-point electrodes submerged in the aqueous phase coupled with planar ground electrode suspended in the gas phase above the water surface has been developed and analyzed for the removal of low concentrations of phenol. Two types of ground electrodes were evaluated. One type consisted of a solid disk made of stainless steel, and the second type consisted of a disk made of high porosity reticulated vitreous carbon (RVC). The liquid-phase discharge leads to the formation of hydrogen peroxide and hydroxyl radicals, and the gas-phase discharge leads to the formation of ozone. The reticulated carbon electrode produced a higher number and more uniform distribution of plasma channels in the gas phase above the liquid surface. This case also led to the largest amount of ozone dissolved in the liquid phase. The combined action of the reactive species formed in the gas and the liquid phases on the degradation of phenol, the formation...

Electro discharge machining of nickel–titanium shape memory alloys

Abstract: Electro discharge machining (EDM) is a common fabrication process for miniaturized components in medical technology and micro engineering today. As EDM induces material changes in the near surface zone, the surface integrity becomes ever more important, the smaller the components are. In order to characterize the influence of EDM on the near surface zone, basic metallurgical investigations on pseudo-elastic NiTi shape memory alloys (SMAs) were carried out. Material removal in EDM depends on the electric discharge processes between the tool and the workpiece electrode in a dielectric fluid. Material is removed by melting and vaporization in single sparks. This results in craters with varying size and depth depending on the discharge energy. The microstructure of this melting zone is characterized by hollows, cracks and precipitation. Cracks open at the surface in consequence of randomly and locally overlapping thermal shocks. The cracks grow vertically into the material, starting at the surface. In the melting zone, significant precipitations were detected and subsequently identified by EDX as titanium carbides. The material removal rate, which is an important process factor in manufacturing, approximately increases in linear proportion with the discharge energy, and achieves commercially interesting values by using an electrode made of copper and tungsten. The results of the microstructure analysis require the removal of the near surface zone to ensure the properties of the components. This is possible via a smooth EDM-process, followed by electrolytic polishing.

Effect of electrical pulse forms on the CO2 reforming of methane using atmospheric dielectric barrier discharge

Abstract: Methane conversion using an electric discharge has been studied for many years. Recently, many research groups have developed high-frequency pulsed plasma reaction for methane conversion to higher hydrocarbons and synthesis gas. CO2 reforming of methane to synthesis gas has also attracted considerable interest as a method of utilization of the greenhouse gases, CO2 and CH4, which occupy most of man-made greenhouse gases. In this study, the influence of pulse form of applied voltage on methane and carbon dioxide conversions and product selectivity has been investigated using a cylindrical type DBD reactor. For this purpose, two kinds of power supply were compared, that is, AC power supply which has a high-frequency sinusoidal wave form, and AC pulse power supply which has modified AC pulse wave form. The conversions of methane and carbon dioxide were enhanced using pulsed plasma. The lower pulse width was more profitable economically.

Method, Drilling Machine, Drill bit and Bottom Hole Assembly for Drilling by Electrical Discharge by Electrical Discharge Pulses

Abstract: Machine for ground drilling, with a circulating fluid, by the utilization of electric discharge generated by high-voltage pulses between electrodes. It may comprise: —A drill-bit 1 with electrodes movable relative to each other, so that bottom-hole physical contact be secured for all the electrodes 4 on all bottom-hole topographies. —Pointed hydraulic nozzles for jetting the fluid, to remove primary cuttings and with pressure expansion across the nozzles 7 at no less than 4 MPa. —A high-voltage pulse generator deployed down-hole at a minimum distance from the drill-bit 1 . —A rotating or oscillating bit causing the borehole cross-sectional excavation to occur, and electric discharge between a plurality of electrodes situated on the bit face along one or a few radii and tangents. —A bottom hole assembly for annular hole-making with core storage, transportation, down-hole closed loop discharge fluid circulation. A discharge fluid storage may be incorporated. A drilling method is also described.

Pulsed volume discharge in a nonuniform electric field at a high pressure and the short leading edge of a voltage pulse

Abstract: It is shown that a volume discharge is formed in a nonuniform electric field for the short leading edge of a voltage pulse and nanosecond pulse duration without any additional preionisation source in various gases at pressures higher than atmospheric (6 atm in helium and 3 atm in nitrogen). Lasing at atomic transitions in Xe is obtained in an Ar—Xe mixture under a pressure of 1.2 atm for an active length of 1.5 cm. A record-high specific power input (more than 0.8 GW cm-3 under a pressure 1 atm in air) is realised in the volume discharge stage. The volume discharge is formed due to preionisation of the discharge gap by fast electrons accelerated due to amplification of the electric field in the cathode region and in the gap. In a nonuniform electric field, volume discharge is realised under a quasistationary voltage from 10 to 180 kV across the gap, at a pulse repetition rate of up to 160 Hz and for various discharge gap geometries.

Shielded electrostatic probe for nonperturbing plasma measurements in Hall thrusters

Abstract: Electrostatic probes are widely used to measure spatial plasma parameters of the quasineutral plasma in Hall thrusters and similar E×B electric discharge devices. Significant perturbations of the plasma induced by such probes can mask the actual physics involved in the operation of these devices. In Hall thrusters, probe-induced perturbations can produce changes in the discharge current and plasma parameters on the order of their steady-state values. These perturbations are explored by varying the material, penetration distance, and residence time of various probe designs. A possible cause of these perturbations appears to be the secondary electron emission, induced by energetic plasma electrons, from insulator ceramic tubes in which the probe wire is inserted. A new probe in which a low secondary electron emission material, such as metal, shields the probe ceramic tube, is shown to function without producing such large perturbations. A segmentation of this shield further prevents probe-induced perturbati...

Description of the discharge process in spark plugs and its correlation with the electrode erosion patterns

Abstract: The phases of the discharges in spark plugs were studied with a high-speed camera and an oscilloscope. The discharges were done using samples of nickel alloys and platinum as cathode in air at pressures ranging from 100 to 900 kPa. For low pressures (100 kPa), a glow discharge occurs after the breakdown. For higher pressures, an arc discharge follows the breakdown and changes into a glow discharge when the current decreases. The damage produced on the cathode surface was analyzed with scanning electron microscopy and white light interferometry and was correlated with the corresponding discharge. The craters on the surface are mainly produced by the breakdown and arc discharge. The glow discharge delivers energy to the cathode in a large area and produces a negligible material damage. The movement of the arc hot spot produces further craters that are commonly overlapped. Transitions from glow to arc modes produce new small craters, which in some cases can be arranged along polishing traces. This work is relevant for the development of new electrode materials for spark plugs and electrical contacts.

Simplified model of underwater electrical discharge.

Abstract: A model of the underwater discharge with initiating wire is presented. The model reveals the nature of similarity parameters which have been phenomenologically introduced in earlier experimental research in order to predict behavior of different discharges. It is shown that these parameters naturally appear as a result of the normalization of differential equations, which determines the process of underwater wire initiated discharge. In these equations the energy conservation law for wire material evaporation and the dependence of plasma conductivity on the energy dissipated in the discharge are implied to calculate the time varying resistance of the discharge gap. The comparison of calculations with the experimental results shows that good agreement is achieved when modification of these parameters is introduced. These new similarity parameters are functions of the original similarity parameters, hence the law of the similarity of underwater electrical discharge is preserved.

Investigation of coupling between chemistry and discharge dynamics in radio frequency hydrogen plasmas in the Torr regime

Abstract: We present the results of a study of a capacitively coupled hydrogen discharge by means of a one-dimensional numerical fluid model and experiments. The model includes a detailed description of the gas-phase chemistry taking into account the production of H? ions by dissociative attachment of H2 vibrational levels. The population of these levels is described by a Boltzmann vibrational distribution function characterized by a vibrational temperature TV. The effect of the dissociative-attachment reaction on the discharge dynamics was investigated by varying the vibrational temperature, which was used as a model input parameter. Increasing the vibrational temperature from 1000 to 6000?K affects both the chemistry and the dynamics of the electrical discharge. Because of dissociative attachment, the H? ion density increases by seven orders of magnitude and the H? ion density to electron density ratio varies from 10?7 to 6, while the positive ion density increases slightly. As a consequence, the atomic hydrogen density increases by a factor of three, and the sheath voltage drops from 95 to 75?V. Therefore, clear evidence of a strong coupling between chemistry and electrical dynamics through the production of H? ions is demonstrated. Moreover, satisfactory agreement between computed and measured values of atomic hydrogen and H? ion densities gives further support to the requirement of a detailed description of the hydrogen vibrational kinetics for capacitively coupled radio frequency discharge models in the Torr regime.

Dielectric coupled CO2 slab laser

Abstract: An slab CO2 laser includes spaced-apart elongated slab electrodes. A lasing gas fills a discharge gap between the electrodes. An RF power supply is connected across the electrodes and sustains an electrical discharge in the lasing gas in the discharge gap. Either one or two ceramic inserts occupy a portion of width of the electrodes and in contact with the electrodes. A discharge gap is formed between the portions of the width of the electrodes not occupied by the insert or inserts. Provision of the ceramic insert or inserts increases the resistance-capacitance (RC) time constant of the electrode impedance by increasing the capacitive component of the time constant. This hinders the formation of arcs in the discharge, which, in turn enables the inventive laser to operate with higher excitation power or higher lasing-gas pressure than would be possible without the dielectric insert. The ceramic insert also decreases the difference in impedance of the electrodes with and without a discharge. This leads to a better-behaved discharge, and a discharge that is easier to light.

Nanopowder synthesis using pulsed arc discharge and applied magnetic field

Abstract: Nanopowder synthesis systems in which a pulsed magnetic field is applied to electrodes of precursor material, in close proximity to an electrical discharge arc that is formed between the electrodes, to attain increased yields of nanopowder. A magnet insert of a coating precursor material is used to coat the nanopowder and thereby reduce nanoparticle agglomeration.

Diesel particulate matter and NOx removals using a pulsed corona surface discharge

Abstract: A pulsed corona surface discharge (PCSD) system was established for particulate matter (PM) and NOx removals from a diesel engine. The PCSD was carried out with a dielectric barrier discharge (DBD) reactor and a pulse power supply at atmospheric pressure and room temperature. The DBD reactor consisted mainly of an alumina (Al2O3) tube and a stainless steel rod (cathode) inserted in the alumina tube, and an aluminum coil (anode) wound on the outside surface of the Al2O3 tube. Pulse voltage was applied to the outside Al coil and stainless steel rod. PM was removed at a rate of 89% at maximum with 40% NOx removal. Relations of pulse voltage and frequency to PM and NOx removals were investigated. PM was oxidized by NO2 and other kinds of active oxygen species, such as O and O3 from plasma discharges. A surface adsorption/desorption and PM oxidation model of PM removal was established. The kinetic equations and their constants were given. © 2004 American Institute of Chemical Engineers AIChE J, 50:715–721, 2004

Surface Treatment of Polyethylene Terephthalate Film Using Atmospheric Pressure Glow Discharge in Air

Abstract: Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (PET) film surface for improving hydrophilicity using the non-thermal plasma generated by atmospheric pressure glow discharge (APGD) in air is conducted. The discharge characteristics of APGD are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena, and the surface properties of PET before and after the APGD treatment are studied using contact angle measurement, x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It is found that the APGD is homogeneous and stable in the whole gas gap, which differs from the commonly filamentary dielectric barrier discharge (DBD). A short time (several seconds) APGD treatment can modify the surface characteristics of PET film markedly and uniformly. After 10 s APGD treatment, the surface oxygen content of PET surface increases to 39%, and the water contact angle decreases to 19°, respectively.

Water treating system

Abstract: PROBLEM TO BE SOLVED: To provide a water treating system which is particularly improved in efficiency of decomposing hardly decomposable materials dissolved in water out of water treating systems using a free radical treating method by electric discharge SOLUTION: The water treating system treating object water to be treated 2 in a water vessel 1 by a free radical treating method is provided with a gas flow passage 41 making a gas 70 for free radical treatment flow in to be jetted to the object water to be treated 2 and discharging electrodes having a discharging part 40 for generating electric discharge to produce free radical from the gas 70 COPYRIGHT: (C)2006,JPO&NCIPI

Effect of the pump intensity on the efficiency of a KrF excimer electric-discharge laser on a He - Kr - F2 mixture

Abstract: The effect of the pump parameters on the efficiency of operation of a KrF gas-discharge excimer laser on a He-Kr-F{sub 2} mixture is studied. A theoretical model of the excitation system and the kinetic processes in the plasma of this laser is developed. A pump system based on an LC inverter with a spark gap as a high-voltage switch, automatic UV preionisation, and a low-inductance discharge circuit is created. To increase the efficiency and the output energy of the KrF laser based on a He-Kr-F{sub 2} mixture, it is proposed to enhance the pump intensity to 4 MW cm{sup -3} by increasing the inductance between the LC inverter and the discharge circuit to 100 nH. An output energy of 1 J at an efficiency of 2% is achieved for the first time for the KrF laser operating on this mixture. (lasers)

Electric discharge machine and machining method therefor

Abstract: In an electric discharge machine and a machining method therefor according to the invention, an electrode (21) and an electrode guide holder (25) are attached to an electrode holder (23) in advance, and the electrode holder (23) is mounted on a main shaft (13), whereupon a grip arm (29) is caused to grip the electrode guide holder (25) and move the electrode guide holder (25) to the front end of the electrode (21). With an electrode guide (61) supporting the front end of the electrode (21), machining is performed. In such electric discharge machine and machining method therefor, when the electrode is consumed in fine hole electric discharge machining, requiring electrode displacement, the electrode displacement operation can be performed in a short time and reliably.

Transverse Electric Discharges in Supersonic Air Flows: Mechanisms of Discharge Propagation and Instability

Abstract: High-speed photographic recording is used to study the propagation dynamics of a pulsed transverse discharge in supersonic jets. It is demonstrated that, rather than destroying the discharge channel, the flow causes it to drift and defines the rate of propagation and, accordingly, the configuration of the discharge channel. Because a transverse discharge always has a channel part perpendicular to flow, such a discharge cannot be steady in principle. The extent of the discharge along the flow is limited by repeated breakdowns associated with one of two mechanisms of instability. The first mechanism is caused by the instability due to external electric circuit; in so doing, the repeated breakdown is the effect rather than the cause of the oscillatory pattern of burning of the discharge. In the current generator mode, when the characteristics of the external circuit do not affect the discharge, the repeated breakdown proper is the mechanism of instability of the discharge. This breakdown occurs, as a rule, between the anode and cathode parts of the discharge channel.

Combustion enhancement with silent discharge plasma

Abstract: A device that uses electrical discharges/nonthermal plasmas in a gaseous medium to activate a fuel or fuel-oxidizer mixture to promote more effective and efficient combustion, in which a dielectric barrier discharge or silent discharge plasma is used to break up larger organic molecules (the fuel) into smaller ones that are more easily and completely combusted. The discharge also creates free radicals that promote more efficient combustion. The device is a cylindrical, coaxial (cylinder in a cylinder) dielectric barrier discharge/silent discharge plasma reactor. It includes two conducting electrodes, one or both of which are covered by a dielectric material. The electrodes are separated by a thin, gas-containing space. A high voltage is applied to the electrodes to create electric discharge streamers in the gas. The discharges are the source of the nonthermal plasma.

Ozone generation by hollow-needle to plate electrical discharge in an ultrasound field

Abstract: The effect of ultrasound waves on the production of ozone by dc electrical discharge in air, at atmospheric pressure, with a single hollow-needle to plate electrode enhanced by the flow of air through the needle for both polarities of the needle, different airflow rates and currents has been studied experimentally It was found that the application of ultrasound increases ozone generation for the discharge, with the needle negatively biased, and has no effect on ozone production for the discharge when the needle is biased positively For the discharge with the needle biased negatively, the ozone generation increases with the increase of the ultrasound transducer surface amplitude and decreases with the increased airflow rate through the needle

Electric discharge device and air purifying device

Abstract: A discharge device for generating a streamer discharge includes a discharge electrode and a counter electrode. The discharge electrode is in the a shape of a wire or rod and is disposed substantially parallel to the counter electrode. Thus, even when a tip of the discharge electrode becomes worn out, a shape of the tip of the discharge electrode remains unchanged and a distance between the discharge electrode and the counter electrode remains unchanged. As a result, even when the tip of the discharge electrode becomes worn out, the streamer discharge stability will not fall.