Begell House Inc.
High Temperature Material Processes: An International Quarterly of High-Technology Plasma Processes
HTM
1093-3611
2
1
1998
RADIATION EMISSION OF THERMAL PLASMA IN 02, H2O, C02 AND AIR
1-14
H.
Riad
Departement d'Enseignements Generaux et Techniques, Ecole Mohammadia d'ingenieurs, Universite Mohamed V, Rabat-Agdal, Maroc
A.
Cheddadi
Faculté des Sciences et Techniques de Settat, B.P. 577, Settat, Maroc
Y.
Neghizadeh-Kashani
Universite Paul Sabatier, 118 route de Narbonne, F31062 Toulouse cedex 4, France
Alain
Gleizes
Centre de Physique des Plasmas et de leurs Applications de Toulouse (CPAT) UMR n° 5002 − Université Paul Sabatier, 118 Route de Narbonne F31062 Toulouse Cedex 4 - France
We present the calculation of net radiation emitted by the hottest regions of various thermal plasmas, in which we consider that the molecules are dissociated. This computation have been effected, in the pure oxygen, water, carbon dioxide and air thermal plasmas assuming isothermal and local thermodynamic equilibrium (LTE) medium, by solving the radiative transfer equation. The results show that the nature of the species has a great influence on the net emission coefficient. In spite of the strong absorption of the resonance lines, these lines constitute in general the main contribution to the total net emission.
PERIODIC LIGHT PERTURBATION IN AN ARGON DISCHARGE AT ATMOSPHERIC PRESSURE
15-24
F.
Richard
GREMI - Universite d'Orleans - BP 6759 - 45067 ORLEANS CEDEX 2
J.-M.
Cormier
GREMI-ESPEO, CNRS-Universite d'Orleans, BP 6759, 45067 Orleans Cedex 2, France
Stephane
Pellerin
GREMI, CNRS-Universite d'Orleans, BP 6759, 45067 Orleans Cedex 2, France LASEP, Universite d'Orleans - Antenne de Bourges, BP4043, 18028 Bourges, France
V.
Dalaine
GREMI - Universite d'Orleans - BP 6759 - 45067 ORLEANS CEDEX 2
J.
Chapelle
LASEP, Centre Universitaire de Bourges, Rue Gaston Berger, BP 4043, 18028 Bourges Cedex, France
High speed photography of a low current discharge in argon at atmospheric pressure has been performed using an electronic camera. The exposure time is adjustable between 50 ns and 1 µs. The pictures obtained for various experimental conditions show a peculiar longitudinal distribution of light pearls which is of a great interest for good understanding of transitional arc-discharge behaviour. Measurements of pearls-light velocities have been carried out in relation with the electric field strength. The frequencies of oscillations are given as a function of the current. We show in this paper that such an atmospheric discharge is governed by non equilibrium effects.
RELATION BETWEEN THE FLOW REGIME OF A PLASMA TORCH AND ITS ACOUSTIC BEHAVIOR
25-33
J. M.
Badie
C. N. R. S., Institut de Science et de Genie des Materiaux et Procedes B. P. 5, Odeillo, F-66125 Font-Romeu Cedex
J.
Bresson
L.M.A.I. UNIV. PERPIGNAN, 52 av. de Villeneuve, 66860 Perpignan cedex
A.
Daif
I.M.P.-CNRS, BP.5, Odeillo, 66125 Font-Romeu cedex - France
B.
Granier
Institut de science et de Genie des Materiaux et Procedes B.P.5 Odeillo 66125 Font - Romeu, France
In order to characterize the working regime of an argon plasma torch we measured and analysed by fast Fourier transform (FFT) the four following parameters : torch voltage, torch current, net radiative power emitted by the plasma jet, and noise (acoustic pressure) emitted by the torch. At high flow rate we observed a turbulent behavior characterized by a high correlation voltage -acoustic pressure or at lower flow rate a broad band spectrum whose global amplitude decreases with flow rate. These behaviors are attributed to the fluctuations of the arc root position. At low flow rates we observed in the acoustic pressure spectrum a narrow peak whose frequency decreases with flow rate and whose maximum amplitude coincides with turbulent laminar transition. We suggest these acoustic pressure fluctuations could result from the electric self oscillations of the arc. We give some results for other types of gases.
LARGE AMPLITUDE OSCILLATIONS IN ELECTRIC ARCS SUSTAINED ON HETEROGENEOUS ELECTRODES IN GASEOUS ATMOSPHERE
35-47
J. L.
Doremieux
CNRS-CECM 15 Rue Georges Urbain 94407 VITRY cedex
R.
Haug
Universite PARIS XI, Laboratoire de Physique des Gaz et des Plasmas, Equipe DEE SUPELEC Plateau du Moulon 91190 Gif-sur-Yvette
In an electric arc, which is free burning in a gaseous atmosphere between electrical contact pieces, or during etching by arcing of oxidised metal surfaces, one can observe large amplitude voltage oscillations. These oscillations should be distinguished from the ordinary voltage noise observed in most of electric arcs. They are related on the nature of the cathode material, notably on the presence on the surface of particles or layers of insulating or low conduction material, such as oxides or nitrides. The light intensity emitted by the arc is time related with the arc voltage oscillations. Interpretation of the origin of these oscillations involves temperature variations on the cathode surface and in the plasma column, and fluctuations of the concentration of the metal vapour content in the plasma.
SPATIAL FLUCTUATIONS OF 'GLIDING' ARC
49-68
Stephane
Pellerin
GREMI, CNRS-Universite d'Orleans, BP 6759, 45067 Orleans Cedex 2, France LASEP, Universite d'Orleans - Antenne de Bourges, BP4043, 18028 Bourges, France
J.-M.
Cormier
GREMI-ESPEO, CNRS-Universite d'Orleans, BP 6759, 45067 Orleans Cedex 2, France
K.
Musiol
Marian Smoluchowski Inst. of Physics, Jagellonian University, ul. Reymonta 4,30-459 Krakow, Poland
B.
Pokrzywka
Mt.Suhora, Observatory of Cracow Pedagogical University, ul. Podchorazych 2, 30-084, Krakow, Poland
J.
Koulidiati
Laboratoire de Physique et Chimie de l'Environnement, Université de Ouagadougou, Burkina Faso
F.
Richard
GREMI - Universite d'Orleans - BP 6759 - 45067 ORLEANS CEDEX 2
J.
Chapelle
LASEP, Centre Universitaire de Bourges, Rue Gaston Berger, BP 4043, 18028 Bourges Cedex, France
Gliding arc discharges are the subject of renewed interest in applications to a variety of chemical reactions. A gliding arc is created by a weakly ionised gas flowing between two electrodes. The reacting gas introduced at the electrode base blows the arc column upwards. These devices can be applied in industry mainly for decontamination and general gas treatment. We describe the different types of arc motion (arc root jump, arc string breakdown...) observed during high voltage DC work and their importance for the gliding arc devices efficiency.
DYNAMIC BEHAVIOUR OF A NITROGEN D.C. TRANSFERRED DOUBLE ARC
69-81
B. G.
Cheron
UMR CNRS 6614, Universite de Rouen - Place Emile Blondel 76821 Mont Saint Aignan Cedex - France
A.
Bultel
UMR CNRS 6614, Universite de Rouen - Place Emile Blondel 76821 Mont Saint Aignan Cedex - France
B
Maheu
UMR CNRS 6614, Universite de Rouen - Place Emile Blondel 76821 Mont Saint Aignan Cedex - France
The dynamic behaviour of a double transferred arc is experimentally analysed. The arc chamber is equipped with four optical fibers aimed at the observation of arc space-time fluctuations. Terminal voltages and currents are also recorded. A particular low frequency behaviour of the arc is pointed out. It is characterized by erratic skips from rotating to quasi stable fastening on the primary nozzle-shaped anode. In either case the arc root looks rather evenly distributed than located in a definite position. The disappearing of the HF fluctuations when replacing the anode material by a better heat conductor material confirms the important stabilizating role played by the electrode cooling
NONLINEAR DYNAMICS : WHAT FOR ?
83-101
C.
Letellier
INSA of Rouen - LEPS - UMR 6614 - CORIA Place Emile Blondel - 76131 Mont Saint Aignan Cedex - France
L.
Le Sceller
INSA of Rouen - LEPS - UMR 6614 - CORIA Place Emile Blondel - 76131 Mont Saint Aignan Cedex - France
G.
Gouesbet
Laboratoire d'Energetique des Systemes et Precedes (LESP), UMR CNRS 6614, CORIA, INSA de Rouen, and University of Rouen, Mont-Saint-Aignan Cedex, France
This paper presents an introduction to the theory of nonlinear dynamical systems, emphasizing some basic facts and recent advances. The point of view is focused on the analysis of signals. The described methods can be applied to many fields (fluid mechanics, chemistry, astrophysics, electronics,...) and should also be useful to the community of plasma workers.
CHARACTERIZATION OF COMPLEX DYNAMICAL REGIMES, UP TO SPATIO-TEMPORAL CHAOS, IN PLASMAS
103-115
G.
Bonhomme
Laboratoire de Physique des Millieux Ionises, Universite Henri Poincare, F-54506 Vandaeuvre-les-Nancy Cedex, France
A
Atipo
Laboratoire de Physique des Milieux Ionises - URPRES-A 7040 du CNRS Universite Henri Poincare - 54506 Vandoeuvre-les-Nancy - France
X.
Caron
Laboratoire de Physique des Milieux Ionises - URPRES-A 7040 du CNRS Universite Henri Poincare - 54506 Vandoeuvre-les-Nancy - France
E.
Gravier
Laboratoire de Physique des Milieux Ionises - URPRES-A 7040 du CNRS Universite Henri Poincare - 54506 Vandoeuvre-les-Nancy - France
Characterizing space-time fluctuations is of first importance to understand the non linear phenomena involved in unstable or turbulent fluid or plasma flows.
Along with the great development observed during the last years in non linear dynamics, new methods in data processing have been proposed. Among these methods the biorthogonal decomposition (BD), enabling to reduce space-time data with the maximum efficiency to a finite set of separate modes is a particularly convenient tool. The eigenmodes come out from the numerical analysis and are not imposed from outside as in the Fourier decomposition. Making a partial reconstruction from the weighted sum of spatial and temporal eigenfunctions obtained gives a mean to separate coherent structures from background stochastic fluctuations.
After a short description of the BD we present two illustrative examples. Both of them are devoted to the characterization of transitions from regular to spatio-temporal chaos or turbulence in laboratory plasmas.
NATURE OF ARGON AND NITROGEN ELECTRIC ARC FLUCTUATIONS IN PLASMA TORCH
117-128
A.
Kaminska
Institute of Electric Power Engineering - Poznan University of Technology ul.Piotrowo 3A - 60-965 Poznan - Poland
Michel A.
Dudeck
ICARE Inst.-CNRS and University of Paris 6, 75252 Paris, France
The electric arc modes of operation in the plasma torch with the cylindrical anode and vortex stabilisation are studied experimentally. Three arc modes are observed but especially two are investigated: the restrike mode and the takeover mode. Particularly the attention is given to the difference of the behaviour of the arc in argon, nitrogen and mixture of argon-nitrogen. The results show that the takeover mode is characteristic for argon arc. The restrike mode occurs for specified argon arc conditions with the thermal breakdown. The restrike arc mode is typical for nitrogen and mixture of argon-nitrogen with electrical breakdown. The time of arc root displacement on anode surface and time of breakdown, the amplitude of fluctuation as functions of arc current and pressure are shown and discussed.
TRANSIENT THREE DIMENSIONAL SIMULATION OF ELECTRIC ARC
129-142
Clarisse
Delalondre
Laboratoire National d'Hydraulique - EDF, 6 Quai Watier - 78400 Chatou - France
M.
Gonzales
CPAT - Universite Paul Sabatier - 118 route de Narbonne - 31062 Toulouse cedex - France
Olivier
Simonin
Institut de Mecanique des Fluides de Toulouse, IMFT, Universite de Toulouse, CNRS - Toulouse,
FRANCE
Said
Zahrai
ABB Corporate Research - 721 78 Vasteras - Sweden; FaxenLaboratoriet, Kungl. Tekniska Hogskolan 100 44 Stockholm, Sweden
This paper describes quantitative numerical investigations of turbulence and arc interaction carried out in our laboratories in the frame of industrial applications such as electric arc furnaces and high voltage circuit breakers. The capabilities of k-epsilon models to account for the laminarization process due to large variations of the viscosity is studied in two dimensional axisymetrical stationary simulations of arc flow. A first attempt at modelling the effects of turbulent fluctuations on electrical source terms is also presented. A second order closure model has been used in order to improve the turbulent flux predictions by taking into account the large anisotropy of the turbulent motion. The second part of this paper is devoted to transient and three dimensional electric arcs modelling using direct simulation methodology. Instationary movements of arc due to the self-induced magnetic forces and the influence of fluid flow have been calculated in simple geometry (arcs between plate electrodes). Computations of statistical properties have been performed in order to study the effect of turbulent fluctuations on electric arcs.
STRUCTURE AND PROPERTIES OF CARBON AND HYDROCARBON FILMS DEPOSITED IN PLASMA OF LOW-PRESSURE ARC AND UNBALANCED DC MAGNETRON
143-154
I.A.
Anisimova
Institute of Chemistry and Chemical Technology - Kyrgyz National Academy of Sciences Prospect Chui 265 A - 720071 - Bishkek - Kyrgyz Republic
V.P.
Anisimov
Institute of Chemistry and Chemical Technology - Kyrgyz National Academy of Sciences Prospect Chui 265 A - 720071 - Bishkek - Kyrgyz Republic
V.P.
Makarov
Institute of Chemistry and Chemical Technology - Kyrgyz National Academy of Sciences Prospect Chui 265 A - 720071 - Bishkek - Kyrgyz Republic
D.K.
Otorbaev
Institute of Chemistry and Chemical Technology - Kyrgyz National Academy of Sciences Prospect Chui 265 A - 720071 - Bishkek - Kyrgyz Republic
Amorphous hydrogenated carbon films were deposited in the plasma of a low-pressure arc discharge burning at the evaporating graphite electrode and in the plasma of a unbalanced magnetron sputtering discharge in different gas environments (Ar, CH4). The film structure was investigated by micro-diffraction method of transmission electron microscopy. Influence of the deposition technique and of the gas composition on the structure and on optical and electrical properties of the deposited films have been investigated.
A SIMPLIFIED COMPUTATION OF THE ELECTRICAL CHARACTERISTICS OF A RF INDUCTION PLASMA
155-163
Jean Pierre
Ploteau
GE44 - LRTI / CRTT - BP 406 - 44602 Saint-Nazaire cedex - France
J.
Fouladgar
GE44 - LRTI / CRTT - BP 406 - 44602 Saint-Nazaire cedex - France
G.
Develev
GE44 - LRTI / CRTT - BP 406 - 44602 Saint-Nazaire cedex - France
The simplified simulation of an induction RF plasma torch is made using a transformer model. The primary of the transformer is the plasma and the secondary is constituted by the inductor. The plasma size is approximated for a given quartz torch, and a given supplied voltage. This model allows us to obtain the electrical characteristics of the plasma torch. The electrical behaviour of the plasma is observed for different voltages, and for different argon flow rates. Then, the obtained results are compared with more advanced numerical models. The results are in good agreement with measurements developed on the 30 kW radio frequency installation.