Wyniki 1-7 spośród 7 dla zapytania: authorDesc:"Ali HENNAD"

Three-dimensional modelling of filamentary discharge using the SG Scheme coupling at time splitting method

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In this paper, we have developed a tri-dimensional numerical modelling of filamentary discharge, which enabled us to study the streamer discharge's propagation at high pressure, in a uniform electrical field. The transport equations and Poisson's equation formed self-consistent model. We use Scharfetter and Gummel schemes SG and SG0 coupling at time splitting method to resolve the transport equations system. The Poisson's equation is resolved by the tri- diagonal method coupled with the over-relaxation method to calculate the electrical field. Streszczenie. W artykule opisano budowę modelu 3-D wyładowania włókienkowego, który posłużył do badań propagacji wyładowania wstęgowego przy wysokim ciśnieniu w jednorodnym polu elektrycznym. Model oparty jest na równaniach Poisson’a i transportu. W celu rozwiązania równań transportu, zastosowano metodę sprzężenia SG i SG0 Scharfetter’a i Gummela, natomiast do formuły Poisson’a zastosowano metodę tridiagonalną, w połączeniu z metodą SOR (ang. Successive Over-Relaxation method). (Trójwymiarowe modelowanie wyładowania włókienkowego, z wykorzystaniem metody SG sprzężenia przy podziale czasu). Keywords: 3D Fluid Model, streamer discharge, SG Scheme, Time Splitting Method. Słowa kluczowe: model cieczy w 3-D, wyładowanie wstęgowe, struktura SG, metoda podziału czasu. Introduction The electric discharges at atmospheric pressure and in particular the streamer discharge are usually used to produce plasmas usable for many industrial applications [1] [2]. A considerable amount of theoretical, numerical and experimental effort has been devoted to understand the development of an electron avalanche, its transition into streamers and the streamer fronts propagation [3]. The numerical modeling of the streamer discharge can provide an invaluable help in the field of plasmas. Many difficulties arise with the solution of the continuity equations, due to the very steep shock-like gradients that a[...]

ADBQUICKEST Numerical Scheme for Solving Multi-Dimensional Drift-Diffusion Equations DOI:10.12915/pe.2014.08.020

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We present in this work a multi-dimensional resolution of the Drift-Diffusion equations using the numerical scheme ADBQUICKEST coupling at time splitting method. This will allow us to study the dynamics of particles in the case of electrical discharge to understand their propagation. The obtained results are compared to analytic solutions and to those found in the literature. Streszczenie. W artykule zaprezentowano wielowymiarowe rozwiązanie równań Drift-Diffusion z wykorzystaniem metody ADBQUICKEST. Zaproponowane rozwiązanie pozwala na analizę dynamiki cząstek w stanie wyładowania elektrycznego. Rozwiązanie wielowymiarowe równań Drift-Diffusion z wykorzystaniem metody ADBQUICKEST. Keywords: ADBQUICKEST Scheme, Drift-Diffusion, 3D Modeling, Time Splitting Method Słowa kluczowe: metoda ADBQUICKEST, równania Drift-Diffusion, wyładowanie elektryczne doi:10.12915/pe.2014.08.20 Introduction Numerical simulation of the transported particles dynamics in an electrical discharge is based on the choice of algorithms to solving the numerical model equations of this discharge. For example the modeling of filamentary gas discharges like streamers. Many researchers are interested in numerical modeling to solve the Drift-Diffusion equations. A numerical multidimensional modeling requires the use of a powerful numerical scheme that can, on the one hand, following the strong density gradients and other it is desirable that this scheme is flexible and consumes little computing time for a simple and easy operation. So the algorithms used must meet the constraints of the physical phenomenon and the requirements of computation time. Our work is devoted to the development of an efficient multi-dimensional numerical model to solve the transport equations [1]. Numerical Model The one-dimensional equation of Drift-Diffusion is defined by: (1) [...]

Two-dimensional modeling RF glow discharge at low pressure DOI:10.15199/48.2017.05.08

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This paper presents a contribution to understand the fundamental properties of RF glow discharge based on numerical modeling. A fluid model with two dimensional based on the first three moments of Boltzmann equation, coupled with Poisson’s equation is used in this work. This equation system is written in cylindrical coordinates following the geometric shape of a plasma reactor. Our transport equation system is discretized using the finite volume approach and resolved by the exponential implicit scheme. In this work, we are used the time splitting method to resolve our system. The model allows us to obtain the axial and radial distributions parameters of the discharge at different times of Radio-Frequency cycle (RF). The principal parameters are the electronic density, ionic density, electric potential, electric field and electronic temperature. Streszczenie. W artykule analizowane jest numerycznie wyładowanie jarzeniowe RF przy niskim ciśnieniu. Wykorztano model Płynu Dwuwymiarowego oparty na pierwszych trzech momentach w rówananiu Boltzmanna, w połączeniu z równania Poissona. Ten układ równań opisana we współrzędnych walcowych w reaktorze plazmowym. Określono główne parametry gęstości elektronowej, gęstości jonowej, potencjał elektryczny, pole elektryczne. Dwuwymiarowe modelowanie wyładowania jarzeniowego RF przy niskim ciśnieniu) Keywords: RF glow Discharge, Fluid Model, charged particle transport, time splitting method. Slowa kluczowe: wyładowanie jarzeniowe RF, model cieczy, metoda dzielenie czasu Introduction RF glow discharges are used in a wide variety of applications in modern science and technology [1]. One of the largest and most important fields of application is the microelectronics industry, where RF glow discharges are used for etching of surfaces to form topographical surface features, as well as for depositing thin films. Similarly, glow discharges are used extensively in the materials processing industries for dep[...]

DC glow discharge modelling by using electrons transport parameters from the BOLSIG+ code DOI:10.15199/48.2019.01.50

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In a DC glow discharge, the electric field is homogeneous in the inter-electrode space. The ions striking the cathode create secondary electrons. The electron avalanche creates much electron that ions but electrons being 100 times faster than ions, they drift quickly to the anode where they are absorbed. The ions having a lot of inertia accumulate in the inter-electrodes space, then the number of ions accumulates increases and from an accumulation threshold, the electric field is no longer homogeneous while it decreases on the side anode, which has the effect of slowing the electrons that drift towards the anode. The process continues until the electric field at the anode vanishes. The electrons can no longer pass freely to the anode and are considerably slowed down. The electron number density increases until to equal of the density of ions. A plasma is formed near the anode. The number of charged particles increases and the plasma extends from the anode to the cathode. The extension of the plasma compresses the region of strong field towards the cathode. These phenomena continue until the creation of charged particles is equilibrate (creation=losses). Two regions appear, the sheath and the plasma. The majority of electric discharge in gases (plasma) are built upon the Boltzmann equation. In principle, the combination of the Boltzmann equation, together with the Maxwell equations, needed for computation of the electromagnetic field, describes the physics of many discharges completely provided that this set of equations is equipped with suitable boundary conditions. In practice, however, the Boltzmann equation is unwieldy and cannot easily be solved without making significant simplifications. Fluid models describe the various plasma species in terms of average hydrodynamic quantities such as density, momentum and energy density. These quantities are governed by the first three moments of the Boltzmann equation: continuity[...]

Numerical modeling of plasma Actuator at high pressure DOI:10.15199/48.2018.04.07

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Flow control plasma actuator has been widely studied over the past two decades as a means to reduce drag and improve performance of aerodynamic bodies [1][2][3]. Recently, the most commonly used plasma actuator has become the sliding-dielectric barrier-discharge (SDBD). A typical configuration of the SDBD is indicating the geometrical parameters of interest for its operation. Plasma actuator consists of two electrodes attached to opposite sides of a dielectric sheet. When high voltage pulse sufficient amplitude is applied between the electrodes, the intense electric field partially ionizes the surrounding air producing no thermal plasma on the dielectric surface. The collisions between the neutral particles and accelerated ions generate a net body force on the surrounding fluid leading to the formation of an “ionic wind" [4]. The body force can be used to impart the desired flow control outcome on a given fluid system. The numerical modeling of the plasma produced by a SDBD actuator to which a short high voltage pulse is applied is described in this work. This numerical model offers the advantages of a detailed description of the plasma, providing the spatial and temporal evolution of the charged species and allowing the computation of electrohydrodynamic forces. However, these outputs are meaningful only if the model is able to describe the physics accurately. This last point is the main challenge with the numerical modeling of the plasma at atmospheric pressure, since the experimental validation is difficult to perform for other than very global characteristics of the plasma, such as the velocity of streamers or its spatial extent. In this paper, we outline a numerical simulation methodology for plasma actuators. The transport equations and Poisson's equation formed self-consistent model [5]. We use Scharfetter and Gummel schemes SG and SG0 [6] [7] [8]. Coupling at time splitting method [5] [8] [9] to resolve the [...]

Two-dimensional modeling positive and negative streamer discharge at high pressure DOI:10.15199/48.2018.06.05

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The simulation of a streamer in electric discharge is not a new problem. Indeed, for many years authors have proposed first the simulations in one dimensional considering only the phenomena on the axis. These onedimensional models remain limited and do not fully account for the physics of discharge. This is why many authors have focused on two-dimensional modeling. The basics of the streamer theory were developed by Raether [1], Loeb and Meek [2]. In their model, we explain the movement of the discharge by that of an ionization front that propagates within space between two electrodes. Once the discharge is initialized, we notice that its propagation is assured without the help of any outside agent. Since the propagation of a streamer depends only on its own space charge field, it can propagate towards the cathode or towards the anode. This possibility makes it possible to define two types of streamers: negative streamer (also called Anode-Directed Streamers) and positive streamer (also called Cathode-Directed Streamers) [3]. We describe the results of numerical calculations of negative and positive streamer propagation based on a fully two-dimensional algorithm, which apply of fluxcorrected scheme names ADBQUICKEST to correct and follow the strong density gradients [4]. The development of this algorithm has allowed us to investigate problems in streamer propagation of considerable interest [5][19]. This work presents the results of the algorithm application to questions including the streamer propagation on ionization ahead of the streamer, on applied photoionization and ionization term, on applied field, on initial and boundary conditions for both case of streamer. 2. Model formulation 2.1 Studied configuration The computational domain is a cylinder of radius R = 0.5 cm (Figure 1) [6]. This domain is limited by two metallic electrodes parallel, planes and circular separated by a distance d equal to 0.5 cm. The applied[...]

Modeling glow discharge at atmospheric pressure in argon DOI:10.15199/48.2018.07.47

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Atmospheric Pressure Glow Discharge controlled by dielectric barriers (APGD) plasma sources driven by a radio frequency (RF) power supply are developed to obtain non-equilibrium gas discharge plasmas with large area, high stability, uniformity and reactivity [1,2]. Recently, atmospheric pressure discharges have found several industrial and other applications such as thin film deposition, surface modification, ozone generation, sterilization, bio-decontamination and others. In principle, atmospheric pressure plasma devices can provide a crucial advantage over low-pressure plasmas because they eliminate complications introduced by the need for vacuum [3]. The benefit of their use lies in the fact that they offer the possibility of low production cost without the need for vacuum equipment. The dielectric barrier discharge (DBD) is a common plasma source used for these applications [2]. Most of atmospheric pressure discharges are dielectric barrier discharges (DBDs) operating in the kilohertz [4]. New sources running at much higher frequencies in the RF range are currently under investigation [1, 2, and 3]. Model formulation In this work, the model used to describe the kinetics of the charged particles for the RF glow discharge at atmospheric pressure is the second order fluid model. It is based on the first three momentums resolution of the Boltzmann equation. These three moments are continuity, momentum transfer and energy equations, which are strongly coupled with the Poisson’s equation by considering the local electric field approximation for ions and the local mean energy approximation for electrons. In the present model, the transport equations derived from the first three moments of Boltzmann's equation are written only for electrons and positive ions (1) e e e n Φ S t x       (2) n Φ S t x      [...]

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