Dielectric-barrier discharges (silent discharges) are used on a large industrial scale. They combine the advantages of non-equilibrium plasma properties with the ease of atmospheric-pressure operation. A prominent feature is the simple scalability from small laboratory reactors to large industrial installations with megawatt input powers. Efficient and cost-effective all-solid-state power supplies are available. The preferred frequency range lies between 1 kHz and 10 MHz, the preferred pressure range between 10 kPa and 500 kPa. Industrial applications include ozone generation, pollution control, surface treatment, high power CO2 lasers, ultraviolet excimer lamps, excimer based mercury-free fluorescent lamps, and flat large-area plasma displays. Depending on the application and the operating conditions the discharge can have pronounced filamentary structure or fairly diffuse appearance. History, discharge physics, and plasma chemistry of dielectric-barrier discharges and their applications are discussed in detail.

https://www3.nd.edu/~sst/teaching/AME60637/reading/2003_PCPP_Kogelschatz_dbd_review.pdf

Dielectric-barrier Discharges: Their History, Discharge Physics, and Industrial Applications

Active flow control is a topic in full expansion due to associated industrial applications of huge importance, particularly for aeronautics. Among all flow control methods, such as the use of mechanical flaps, wall synthetic jets or MEMS, plasma-based devices are very promising. The main advantages of such systems are their robustness, simplicity, low power consumption and ability for real-time control at high frequency. This paper is a review of the worldwide works on this topic, from its origin to the present. It is divided into two main parts. The first one is dedicated to the recent knowledge concerning the electric wind induced by surface non-thermal plasma actuators, acting in air at atmospheric pressure. Typically, it can reach 8 m s−1 at a distance of 0.5 mm from the wall. In the second part, works concerning active airflow control by these plasma actuators are presented. Very efficient results have been obtained for low-velocity subsonic airflows (typically U∞ ≤ 30 m s−1 and Reynolds number of a few 105), and promising results at higher velocities indicate that plasma actuators could be used in aeronautics.

https://iopscience.iop.org/article/10.1088/0022-3727/40/3/S01/pdf

Airflow control by non-thermal plasma actuators

The term plasma actuator has now been a part of the fluid dynamics flow-control vernacular for more than a decade. A particular type of plasma actuator that has gained wide use is based on a single–dielectric barrier discharge (SDBD) mechanism that has desirable features for use in air at atmospheric pressures. For these actuators, the mechanism of flow control is through a generated body-force vector field that couples with the momentum in the external flow. The body force can be derived from first principles, and the effect of plasma actuators can be easily incorporated into flow solvers so that their placement and operation can be optimized. They have been used in a wide range of internal and external flow applications. Although initially considered useful only at low speeds, plasma actuators are effective in a number of applications at high subsonic, transonic, and supersonic Mach numbers, owing largely to more optimized actuator designs that were developed through better understanding and modeling of...

Dielectric Barrier Discharge Plasma Actuators for Flow Control

In recent decades particular interest in applications of nonequilibrium plasma for the problems of plasma-assisted ignition and plasma-assisted combustion has been observed. A great amount of experimental data has been accumulated during this period which provided the grounds for using low temperature plasma of nonequilibrium gas discharges for a number of applications at conditions of high speed flows and also at conditions similar to automotive engines. The paper is aimed at reviewing the data obtained and discusses their treatment. Basic possibilities of low temperature plasma to ignite gas mixtures are evaluated and historical references highlighting pioneering works in the area are presented. The first part of the review discusses plasmas applied to plasma-assisted ignition and combustion. The paper pays special attention to experimental and theoretical analysis of some plasma parameters, such as reduced electric field, electron density and energy branching for different gas discharges. Streamers, pulsed nanosecond discharges, dielectric barrier discharges, radio frequency discharges and atmospheric pressure glow discharges are considered. The second part depicts applications of discharges to reduce the ignition delay time of combustible mixtures, to ignite transonic and supersonic flows, to intensify ignition and to sustain combustion of lean mixtures. The results obtained by different authors are cited, and ways of numerical modelling are discussed. Finally, the paper draws some conclusions on the main achievements and prospects of future investigations in the field.

/pdf/plasma-assisted-ignition-and-combustion-2i4ybn8440.pdf

Plasma assisted ignition and combustion

Reactive species in non-equilibrium atmospheric-pressure plasmas: Generation, transport, and biological effects

The barrier discharge: basic properties and applications to surface treatment

The technique of spatially resolved cross-correlation spectroscopy (CCS) is used to carry out diagnostic measurements of the barrier discharge (BD) in air at atmospheric pressure. Quantitative estimates for electric field strength E(x,t) and for relative electron density ne(x,t)/nemax are derived from the experimentally determined spatio-temporal distributions of the luminosity for the spectral bands of the 0-0 transitions of the second positive system of N2 (λ = 337.1 nm) and the first negative system of N2+ (λ = 391.5 nm). These results are used to test the validity of some physical models of electrical breakdown in a BD. The influence of the spatio-temporal structure of the discharge on the chemical kinetics of ozone synthesis is studied by means of a semi-empirical method based on the results of spatially resolved CCS measurements.

https://iopscience.iop.org/article/10.1088/0022-3727/34/21/309/pdf

Spatio-temporally resolved spectroscopic diagnostics of the barrier discharge in air at atmospheric pressure

The techniques of spatially resolved cross-correlation spectroscopy (CCS) and current pulse oscillography were used to carry out systematic investigations of the barrier discharge (BD) in the binary gas mixtures N2/O2 at atmospheric pressure. At very low oxygen concentrations (<500 ppm), the BD was observed in a so-called diffuse mode (also referred to as atmospheric pressure glow discharge, glow silent discharge or homogeneous BD). In the case of the BD filamentary mode, the spatio-temporal distributions of the BD radiation intensities were recorded for the spectral bands of the 0–0 transitions of the second positive (λ = 337 nm) and first negative system of molecular nitrogen (λ = 391 nm). In the case of the diffuse mode, the spectral bands λ = 337 nm, λ = 260 nm (0–3 transition of the γ -system of NO) and λ = 557 nm (radiation of ON2 excimer) were used for this purpose. The velocities of the cathode-directed ionizing waves as well as the effective lifetimes of the excited states N2(C 3 � u)υ� =0 and N + (B 2 � + u )υ � =0 were evaluated from the CCS data. Special attention was devoted to the investigation of the transition between the filamentary and diffuse modes of the BD, this transition being caused by the variation of oxygen content within the range 500–1000 ppm. (Some figures in this article are in colour only in the electronic version)

https://iopscience.iop.org/article/10.1088/0022-3727/38/4/003/pdf

Investigation of the filamentary and diffuse mode of barrier discharges in N 2 /O 2 mixtures at atmospheric pressure by cross-correlation spectroscopy

The entire range of gas phase reaction products, depending on the composition of initial binary mixtures of methane and carbon dioxide in dielectric barrier discharges, has been determined (saturated as well as unsaturated hydrocarbons and oxygenated organic compounds) The macro-kinetics of the basic chemical pathways of the system under consideration has been investigated This system is found to display a strong feedback effect (positive or negative, depending on the initial state of the surfaces, as well as the chemical composition of the feed-gas mixture) It is demonstrated that these properties undergo significant changes during operation, due to surface modification processes (polymer film deposition, its oxidation or reduction) They are found to exert a considerable influence on the chemical efficiency of the discharge (for example, on the absolute and relative chemical yields of the reaction products), the Lissajous figures appear to be a sensitive tool to monitor the operation conditions of the discharge

Synthesis of Organic Compounds from Mixtures of Methane with Carbon Dioxide in Dielectric-Barrier Discharges at Atmospheric Pressure

Es wird die positive Saule einer Neonentladung bei mittleren Gasdrucken untersucht. Ein genaherter Ausdruck fur die Energieverteilungsfunktion der Elektronen wird abgeleitet, der in einem breiten Entladungsstromdichtebereich anwendbar ist. Auf Grundlage der gefundenen Verteilungsfunktion wird eine Diffusionstheorie der positiven Saule entwickelt.



Die elektrische Langsfeldstarke, Elektronentemperatur und Elektronenkonzentration werden in Abhangigkeit von Gasdruck, Entladungsstromstarke und Radius des Entladungsrohres berechnet. Die Theorie erklart sowohl die Kontraktion der Saule als auch deren Verschwinden bei Verringerung des Entladungsstromes.

P. Michel

Papers

The barrier discharge: basic properties and applications to surface treatment

Spatio-temporally resolved spectroscopic diagnostics of the barrier discharge in air at atmospheric pressure

Investigation of the filamentary and diffuse mode of barrier discharges in N 2 /O 2 mixtures at atmospheric pressure by cross-correlation spectroscopy

Synthesis of Organic Compounds from Mixtures of Methane with Carbon Dioxide in Dielectric-Barrier Discharges at Atmospheric Pressure

Untersuchung der positiven Säule der Neonentladung bei mittleren Gasdrücken Teil IV