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In this research, the decomposition of CO2 in CO2/O2 pulsed discharge was studied. The developed model is based on the physical processes involved in the discharge with the CO2 plasma chemistry, the electrical circuit, and the Boltzmann equations. The fundamental chemistry of CO2/O2 gas mixture used in this work is based on a full set of processes regrouped in 113 reactions involving 21 species of the discharge. The obtained numerical results show the temporal variations of electrical parameters and species concentrations of the discharge. We have also studied the effect of some discharge parameters (gas pressure, dielectric capacitance, applied voltage, concentration of O2 in CO2/O2 gas mixture, and frequency) on the discharge behavior.

International audience; This work presents an electric and kinetic study of homogeneous dielectric barrier discharge (DBD) in pure krypton (Kr). The electrical characterization and kinetic analyses of the DBD in Kr are performed. The plasma formation in DBD, excited by sinusoidal voltage at high pressure, was studied. The discharge development, with homogeneous model approach and using extended kinetic scheme, is simulated. The study is based on a spatial homogeneity model including the plasma chemistry, the electrical circuit and the Boltzmann equations’. The temporal variations of discharge voltage, dielectrics voltage, discharge current, electric field and species concentrations are calculated. The plasma kinetics is discussed with the aim to finding the optimal efficiency. The photon generation, under typical operating conditions, was investigated and discussed. The effect of some parameters on the excilamp like pressure, applied voltage, and frequency are investigated in order to identify the optimal parameters for maximum luminous efficiency in the UV range.

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The purpose of this paper is to study the gas heating phenomenon in dielectric barrier discharge (DBD) due to the Joule heating effect for Ne-Xe gas mixtures. In this work, the simulation was performed using a one-dimensional fluid model. The gas temperature profile was calculated by heat conduction equation resolution along gap distance of discharge. The increasing of gas temperature close to the vicinity of cathode is due to the high values in the power deposited in this region. The results show that the gas temperature in DBD excited with rectangular applied voltage waveform is more important than the discharge created by a sinusoidal excitation. For high values of secondary electron emission coefficient (γ) the gas temperature will be increasing. The effect of varying gas mixture composition on gas temperature has been also examined.

The aim of this work is to highlight the influence of the material constructing the anode in wire-to-cylinder negative corona discharge. A numerical simulation is presented where a plasma of pure oxygen has been considered. Three materials (stainless steel, copper, aluminum) are tested. The study is carried at atmospheric pressure and for different temperatures and voltages. The numerical results show the radial distribution of ozone for each wall material. The relationship between the material and its decomposition coefficient is revealed basing on the experimental current–voltage characteristic and in which the current is used as input data.

This paper presents a homogeneous study of xenon dielectric barrier discharge (DBD). The model, including plasma chemistry, electrical circuit, and Boltzmann equation modules, investigates the electrical and physical characteristics of high-pressure DBDs. The model is applied in the case of a sinusoidal voltage at period frequency of 50 kHz and gas pressure of 400 torr. First, we have analyzed the temporal evolutions of the plasma voltage, the current density and the species concentrations. Then, the physical model validity is checked by comparing the model results with a theoretical work. The effect of the kinetic scheme on the electrical parameters, the species concentration, and the total lamp efficiency are also investigated and discussed.

The distribution of the gas temperature, due to the heat Joule effect in dielectric barrier discharge and for different rare gases (Ar, Ne, Xe, and Kr), was investigated using a 1-D time-dependent fluid model. The model is based on the resolution of the transport equation of the electrons and the ions coupled with the Poisson's equation for a parallel-plate dielectric barrier discharge reactor. To consider of gas heating due to ions and electrons, we solve the heat transport equation along of the discharge gap. The results show an increasing of the gas temperature in front of the dielectrics due to heavy ions for different noble gases used (Ar, Ne, Xe, and Kr). The effect of the applied voltage, the gas pressure as well as the secondary electron emission of MgO bombardment by rare gas ions on the gas temperature is also analyzed.

The aim of this work is to highlight, through numerical modeling, the chemical and the electrical characteristics of xenon chloride mixture in XeCl* (308 nm) excimer lamp created by a dielectric barrier discharge. A temporal model, based on the Xe/Cl2 mixture chemistry, the circuit and the Boltzmann equations, is constructed. The effects of operating voltage, Cl2 percentage in the Xe/Cl2 gas mixture, dielectric capacitance, as well as gas pressure on the 308-nm photon generation, under typical experimental operating conditions, have been investigated and discussed. The importance of charged and excited species, including the major electronic and ionic processes, is also demonstrated. The present calculations show clearly that the model predicts the optimal operating conditions and describes the electrical and chemical properties of the XeCl* exciplex lamp.

This paper reports the study of the Kr–Cl2 plasma chemistry in terms of the homogenous model of a dielectric barrier discharge and for two kinds of the applied voltage excitation shape. The effect of Cl2 concentration in the gas mixture, as well as gas pressure and power frequency on the discharge efficiency and the 222 nm photon generation, under typical experimental operating conditions, have been investigated and discussed. Calculations suggest that the overall conversion efficiency from electrical energy to ultraviolet emission in the lamp is in the range of 4.4–12 %, and it will be very affected at high chlorine percentage (>1 %) and high gas pressure (>200 Torr). A comparison between the sinusoidal and the burst excitation waveforms reveals that the burst excitation method provides an enhanced light source performance compared to the sinusoidal wave.

The aim of this work is to highlight some quantities characterizing the Ne/Xe/HCl gas mixture plasma at high pressure and under uniform preionization conditions. This mixture is used as excitation medium for XeCl excimer lasers. A comprehensive model of discharge kinetics is presented. The model combines the physical processes in the discharge with the chemistry of formation and destruction of the excimer molecule. It is based on an extensive reaction scheme including the major electronic and ionic processes. The importance of excited atomic and molecular states is demonstrated. A parametric study is presented.

This paper reports the investigation of the excimer UV emission efficiency in Ne/Xe/HCl mixture in terms of the homogenous model of a dielectric barrier discharge. The computer model developed is based on the Ne/Xe/HCl gas mixture chemistry, the circuit and the Boltzmann equations. The effects of operating voltage, HCl concentration in the mixture as well as gas pressure on the discharge efficiency and the 172, and 308 nm photon generation, under typical experimental operating conditions, have been investigated and discussed. Calculations suggest that the overall conversion efficiency from electrical energy to VUV emission in the lamp is greater than 27%, and it will be very affected at high voltage amplitude and high gas pressure with a significant dependence on the HCl concentration in the gas mixture.

The purpose of this work is to highlight the chemical kinetics in plasma of pure oxygen. A comprehensive model of ozone generation in wire-to-cylinder negative corona discharge is presented. The model combines the physical processes in the discharge with the chemistry of ozone formation. It is based on an extensive reaction scheme including the major electronic and ionic processes. The importance of excited atomic and molecular states is demonstrated. The obtained results show clearly that the surface material affect quite well the ozone decomposition.

In this work, we investigated the effect of gas heating near the electrode of an excimer lamp. Gas heating occurs in the cathode region as ions are accelerated by the high electric field near the cathode. The gas temperature profile was calculated by solving the one-dimensional heat transport equation in the Joule heating approximation without including the effect of reflected particles. The inter-electrode gap was filled with xenon gas and measured 0.5 cm. The model predicts correctly the waveform of the temperature and illustrates the important role of the boundary conditions. The results obtained show clearly that the increase in the temperature in the sheath is limited by the increase in the ion current density in the cathode region due to the electron multiplication.

In this work, an analytical model is used to study the formation of the anodic streamer in high pressure electrical discharge. This model enabled us to see the space variations of the characteristics of the streamer such as the electric field and the propagation velocity of streamer. The validity of the analytic approach is demonstrated by comparing the model results to the data from the literature. A qualitative concord was found. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this paper, we use numerical modeling to study some characteristics of the XeCl laser under homogeneous pre-ionization conditions. The study is executed using a model combining external circuit and plasma kinetics. The model validity is checked by comparing the model results to the experimental data from the literature. A qualitative agreement was found.

This work represents a study of the streamer formation in plasma for XeCl excimer laser at high pressure. It is based on a longitudinal mono-dimensional model of the cathodic zone. In this model, we show the possibility of the streamer development in the cathodic sheath and its propagation during the phase of plasma formation. The model gives the space and time evolution of the electron density and the discharge electric field in the presence of the streamer. The obtained results clearly indicate that, for conditions close to experiments for 50–100 ns laser pulse durations and electron power deposition in the MW/cm3 range in a 300 cm3 chamber, the streamer instability, related to the sheath evolution, patently appears. The drift velocity reaches a typical value of about 108 cm/s.

The purpose of this paper is to study, through numerical modeling, the XeCl kinetics and the mechanisms affecting plasma uniformity in high-pressure discharge pumped excimer lasers. In the model, the plasma is represented by a resistance inversely proportional to the electron density. Time variation of the electron density is obtained by integrating the transport equations coupled to the heavy-species kinetics and to the external circuit. A detailed description of the XeCl molecule and of the associated kinetics has been taken into account, together with the effect of the gas mixture composition on power deposition and the spatial uniformity of the plasma. Calculated discharge current and voltage are compared with experimental results. The obtained results indicate clearly that about 50% of the halogen is consumed at the end of the discharge pulse.

The aim of this work is to study the development of the macroscopic non-uniformity of the electron density of high pressure discharge for excimer lasers and eventually its propagation because of the medium kinetics phenomena. This study is executed using a transverse mono-dimensional model, in which the plasma is represented by a set of resistances in parallel. The time variations of the electron density in each plasma element are obtained by solving a set of ordinary differential equations describing the plasma kinetics and external circuit. The use of the present model allows a good comprehension of the halogen depletion phenomena, which is the principal cause of laser operation premature termination and allows a simple study of a large-scale non-uniformity in preionization density and its effects on plasma electrical and chemical properties. The results obtained indicate clearly that about 50% of halogen is consumed at the end of the pulse.

Theoretical studies of a phototriggered XeCl excimer laser have been performed through the development of a zero-dimensional model and used for conditions close to experiment for about 50–100 ns laser pulse duration with electron power deposition in the MW/cm3 range and inside a 300 cm3 chamber. The well-known parallel resistor network model is used. The plasma generated by the impulse discharge is represented by one or more resistance in parallel, whose conductivity is proportional to the electron density. Time variation of the electron density is obtained by integrating the transport equations coupled to the heavy species kinetic and the external circuit. This study provides the time variation of the discharge characteristics as well as the influence of the gas composition on these characteristics. The results have been discussed and analyzed. Calculated discharge current and voltage are also compared with experimental results. Finally, the use of the present model allows a good comprehension of the halogen depletion phenomena, which is the principal cause of laser ending and allows a simple study of the evolution of a large-scale heterogeneity in preionization density and its effect on electrical and chemical plasma properties.

Des méthodes relativement récentes, comme l’échange d’ions et l’extraction liquide-liquide, ont été largement utilisées pour séparer des métaux à l’état de traces. Pour ceux qui présentent notamment des propriétés analogues, la complexation par des agents chélatants s’avère nécessaire. Du fait de leur grande stabilité thermique et de la diversité des groupements fonctionnels des produits commerciaux disponibles, les résines ont été d’une grande utilité en analyse et dans l’industrie. Cette étude a trait à la rétention de métaux comme le cadmium et le zinc sur les résines acides Amberlite IRC-50, Dowex-50 X8 et Permutit C‑67. Les études en flacon ont mis en évidence une grande affinité de ces éléments pour les résines utilisées, et que l’équilibre est atteint rapidement (30 à 60 min). Les ions Zn2+ et Cd2+ n’utilisaient au maximum que 88 à 91 % de capacité totale des résines étudiées. Le traitement des résultats pour les faibles concentrations a montré que les isothermes sont du type Langmuir comme ceux obtenus par ailleurs sur des échangeurs minéraux.

This work represents a study of the formation and propagation of the streamer during a pulse in a plasma cell with dielectric barriers containing a Ne/Xe gas mixture. It is based on a longitudinal mono-dimensional model of the dielectric barrier discharge. In this model, we show the possibility of streamers development in the cathode sheath and its propagation during the plasma formation stage. The model gives the spatiotemporal variations of the propagation speed, the electric field, and the charged particle density of the streamer's head.

International audience; We discuss new features of the XeCl*-laser kinetics by using a detailed analysis of the results of complex computer models. In particular, we consider the development of a high scale instability in a XeCl*-laser discharge. The emphasis is made on fundamental problems, mainly on the limitation of the macroscopic approach to the study of such strongly nonequilibrium systems. The results obtained indicate especially the discharge proprieties at the plasma centre.

The aim of this work is to highlight some quantities characterizing the anode-directed streamer generated in the Ne/Xe/HCl gas mixture plasma at high pressure and under non-uniform preionization conditions. This mixture is used as excitation medium for XeCl excimer lasers. A comprehensive model of discharge is presented. This model gives the space-time evolution of electron density and electric field, streamer appearance time, streamer expansion distance and velocity. The effect of HCl concentration in the gas mixture, as well as gas pressure and gap distance on streamer characteristics, have been investigated and discussed. Calculations suggest that the streamer velocity is patently affected by the gap distance with a significant dependence on the HCl concentration in the gas mixture.

Plasma display panels (PDPs) are one of the leading technologies in the flat panels market. However, they are facing intense competition. Different fluid models, both one-dimensional (1D) and 2D, have been used to analyze the energy balance in PDP cells in order to find out how the xenon excitation part can be improved to optimize the luminous efficiency. The aim of this work is to present a 1D particle-in-cell with Monte Carlo collision (PIC–MCC) model for PDPs. The discharge takes place in a Xe10–Ne gas mixture at 560 Torr. The applied voltage is 381 V. We show at first that this model reproduces the electric characteristics of a single PDP discharge pulse. Then, we calculate the energy deposited by charged particles in each collision. The total energy is about 19 μJ cm−2, and the energy used in xenon excitation is of the order of 12.5% compared to the total energy deposited in the discharge. The effect of xenon content in a Xe–Ne mixture is also analyzed. The energies deposited in xenon excitation and ionization are more important when the xenon percentage has been increased from 1 to 30%. The applied voltage increases the energy deposited in xenon excitation.

A pulsed dielectric-barrier discharge in xenon has been simulated for operating conditions typical to excimer lamps, in which the discharge is considered spatially homogeneous. The computer model developed is based on the xenon plasma chemistry, the circuit, and the Boltzmann equations. First, the validity of the physical model was checked and compared to experimental and theoretical works, and then the model is applied in the case of a sinusoidal voltage at period frequencies in the range of 50 kHz–2 MHz. The results obtained with the present description are in good agreement with experimental measurements and one-dimensional fluid prediction in terms of electrical characteristics and vacuum ultraviolet (vuv) emission. The effect of operation voltage, power source frequency, dielectric capacitance, as well as gas pressure on the discharge efficiency and the 172, 150, and 147 nm photon generation, under the typical experimental operating conditions and for the case of a sinusoidal applied voltage, have been investigated and discussed. Calculations suggest that the overall conversion efficiency from electrical energy to vuv emission in the lamp is greater than 38%, and it will be very affected at high power source frequency and high gas pressure with a significant dependence on the dielectric capacitance.

Dielectric barrier discharges (DBDs) are a promising technology for high-intensity sources of specific ultraviolet (UV) and vacuum ultraviolet (VUV) radiation. In this work, the microdischarge dynamics in DBDs for Ne–Xe mixtures under the close conditions of excimer lamp working has been investigated. The computer model including the cathode fall, the positive column and the dielectric is composed of two coupled sub-models. The first submodel describes the electrical properties of the discharge and is based on a fluid, two-moments description of electron and ion transport coupled with Poisson's equation during the discharge pulse. The second submodel, based on three main modules: a plasma chemistry module, a circuit module and a Boltzmann equation module, with source terms deduced from the electric model, describes the time variations of charged and excited species concentrations and the UV photon emission. The use of the present description allows a good resolution near the sheath at high pressure and it predicts correctly the waveform of the discharge behaviour. The effects of operation voltage, dielectric capacitance, gas mixture composition, gas pressure, as well as the secondary electron emission by ion at the cathode on the discharge characteristics and the 173 nm photon generation have been investigated and discussed.