Role of Streamers in the Formation of a Corona Discharge in a Highly Nonuniform Electric Field

JETP Letters - The ignition of a corona discharge on a tip electrode with a small radius of curvature in air at atmospheric pressure is studied. It is established that the initiation of the corona...     

Ozone Synthesis in an Electric Discharge between Ferroelectric Electrodes at Atmospheric Pressure

This paper deals with studies of the ozone synthesis by means of an ac discharge (50 Hz) between two parallel ferroelectric plates under radial oxygen flow conditions at atmospheric pressure. Bariumtitanate based ceramic with ? ∽ 6000 was used as ferroelectric material. An important feature of this kind of the discharge is the fact that the operating voltage is well one order of magnitude smaller than that of the silent discharge usually used for the O₃ production. Examples of I — U characteristics are discussed. The absorption of light at 253.7 nm wavelength was used to determine [O₃] within and downstream of the discharge as function of the O₂ flow rate. These results have been examined in terms of a kinetic investigation of the O₃ synthesis based on the so-called plug flow model including the particle balance equations of electrons, O atoms, O₂ and O₃ molecules, respectively. Thus, the measured decrease of [O₃] with increasing flow rate can be explained by the increasing influence of the loss of O₃ by convection on the particle balance of O₃. Furthermore it is shown that inside the plasma reactor [O₃] increases with the radius r. Therefore the data for measured spatial average of [O₃] inside the discharge are lower than that of [O₃] in the flowing afterglow. The last values are identical with that of [O₃] at the exit of the discharge.     

Water Treatment with the Cold Plasma of a Diffuse Nanosecond Discharge in Air at Atmospheric Pressure

Russian Physics Journal - The treatment of wastewater with the atmospheric cold plasma is a promising method to purify it by means of neutralizing various toxic components. The degradation of an...     

Streamers at the Subnanosecond Breakdown of Argon and Nitrogen in Nonuniform Electric Field at Both Polarities

An ICCD camera was used to study plasma glow at the stage of the streamer (ionization wave) formation in the tip–plane gap with a length of 3 mm filled with argon or nitrogen at a pressure of 12.5–400 kPa. Positive and negative nanosecond voltage pulses were applied across the gap. Images of streamer were obtained at different time at its propagation along the gap. A streak-camera equipped with a spectrometer was used to measure time evolution of the radiation intensity of nitrogen molecules at a wavelength of 337.1 nm in several regions along the gap at the negative polarity. Average streamer velocity (1.8 cm/ns) was estimated from experimental data at atmospheric pressure of nitrogen. Amplitude–time characteristics of voltage, discharge current and the current of runaway electron beam behind the aluminum-foil anode with a thickness of 10 μm were measured. Reasons for a diffuse discharge under the given experimental conditions were discussed.     

Oscillatory Motion of Microdroplets of a Droplet Cluster in a Linearly Nonuniform Electric Field

The forces acting on freely levitating water microdroplets in the structure found 15 years ago and called the droplet cluster (A. A. Fedorets, 2004) are considered. It is shown that lowfrequency vertical damping microdroplet oscillations can take place in such a cluster near the equilibrium position, which also exist in the case of instantaneous turn-on of an external electric field. These oscillations are considered from the viewpoint of the Fourier analysis.     

Evolution of a Diffusion Channel in an Inhomogeneous Electric Field of the KrF-Laser Pump Discharge

Russian Physics Journal - The results of studying the 2D-simulation of evolution of a diffusion channel in the KrF-laser pump discharge initiated by the pin on the cathode surface are presented. It...     

Modelling of a Spherical Electric Discharge at Atmospheric Pressure Under Higher Modes of Incident Microwaves

We present a spherical microwave discharge model, which takes into account the higher modes of the incident electromagnetic waves. The discharge model is constructed on the basis of the channel approximation of the LTE plasma. Numerical experiments are carried out for the discharge in an argon at atmospheric pressure. Results are presented for the characteristics of the discharge plasma against the external parameters (the size of the discharge chamber and the applied electromagnetic field mode, power and frequency). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Hydrodynamic Limit for an Arc Discharge at Atmospheric Pressure

In this paper we study a partially ionized plasma that corresponds to an arc discharge at atmospheric pressure. We derive an inviscid hydrodynamic/diffusion limit, characterized by two temperatures, from a system of Boltzmann type transport equations modelling that plasma problem. The original property of this system is that impact ionization is a leading order collisional process. As a consequence, the density of electrons is given in terms of the density of the other species (and its temperature) via a Saha law.     

Electric Field Mechanism of Thin Plasma Jet Formation in an Open Atmospheric Discharge

Russian Physics Journal - Experimental and theoretical investigations of a new form of pulsed periodic discharge burning in the form of a thin plasma jet – apokamp – have been carried...     

Non-Uniform Axial Electric Field in Argon Glow Discharge Plasma

The non-uniform argon dc glow discharge plasma system has been constructed in a very special design to investigate the effects of variable tube radius on plasma parameters. By using isolated computer controlled three couples of a double probe （TCDP） system, the electron temperature, electron density, the reduced electric field, and electron drift velocity are measured at low and intermediate pressures. It is shown that the electron temperature and reduced electric field （density） decreases （increases） as the radius decreases, at low discharge current and pressures. For large radius regions, at high discharge currents and pressures, the behaviour of the plasma parameters of specially reduced electric field change similarly to those in a uniform discharge system.     

The Universe in the Logunov Metric with a Nonuniform Scalar Field

Russian Physics Journal -     

A Model for Diffuse Breakdown in High Pressure Gases at Homogeneous Electric Field Strengs

A model of the breakdown in high pressure gases is presented taking into consideration the finite voltage rise time at the discharge electrodes and a finite initial charge carrier density in the gap. Several types of breakdown could be distinguished important for several applications. Thus, the range of existence of high pressure laser discharges at a given preionization density and circuit parameters can be calculated. Moreover, the change in the breakdown characteristics of high pressure gases at high temperatures is explained. This behaviour seems to be important for understanding the physical processes in circuit breaker chambers.     

Concentric-Ring Patterns in a Helium Dielectric Barrier Discharge at Atmospheric Pressure

We perform the theoretical simulation of the concentric-ring patterns between two parallel electrodes covered with thin dielectric layers within the scope of a two-dimensional diffusion-drift model at atmospheric pressure. The time evolution of the discharge patterns is studied and the concentric-ring patterns with different radii shift alternately. The spatial-temporal evolution of electron density in a cycle at different time scales is performed.     

Compression of a Runaway Electron Flow in an Air Gap with a Nonuniform Magnetic Field

JETP Letters - The first results of study of the compression of a picosecond runaway electron flow in an air electrode gap by a pulsed guiding magnetic field increasing along the electron...     

均匀电场SF6短气隙放电过程动态模拟

根据基本物理定律和流体力学,构建均匀电场下SF₆短气隙放电流体模型,运用通量校正传输法(flux-corrected transport)数值分析大气压下4 mm间隙SF₆的放电过程,展现放电空间带电粒子产生、复合、附着、扩散以及光致电离动态过程,获得了放电间隙电场畸变、带电粒子动力学行为和放电通道形成发展历程和时空分布,根据R-M判据求出模型放电过程中电子崩转向流注的时空临界点,印证了光致电离在流注发展阶段的重要作用.     

The Separation Mechanism of Particles in a Smoke by an Electric Field

It was found that smoke particles smaller than 100nm and of different crystal structures can be separated by an electric field. Tungsten oxide smoke curved in the electric field towards the positive electrode plate. The morphology of the particles and dispersion of particles became good in the electric field. By burning of Pb in a mixture gas of Ar (80%) and O₂ (20%), red and yellow layer structure particles were simultaneously produced. The flow direction of red and yellow smokes changed by applying an electric field (200V/cm). Red particles flowed towards the negative plate and yellow particles flowed towards the positive plate, i.e. two different structures were separated. Simultaneous growth conditions of SnO and SnO₂ were observed and also found that they can be separated by the use of electric field as well as lead oxides. The curve of the smoke is discussed as that the surface net charge was affected by the electric field on the basis of produced particle structure and morphology.     

Formation of a Negative Streamer in a Sharply Nonuniform Electric Field and the Time of Generation of Runaway Electrons

Russian Physics Journal - The formation of a negative streamer in air is investigated at different pressures in a sharply nonuniform electric field under the conditions of nanosecond and...