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Featured researches published by J. Chapelle.


Journal of Physics D | 1996

A spectroscopic diagnostic method using UV OH band spectrum

Stéphane Pellerin; Jean-Marie Cormier; Frédéric Richard; Karol Musiol; J. Chapelle

Noisy and spectrally poorly resolved molecular emission spectra of the 306.357 nm OH band were employed for evaluation of the rotational temperature in different plasma sources, in the temperature range 300 - 6000 K, when an apparatus function of a recording system is unknown. The described method is based on a comparison of experimental data with a theoretical spectrum. The following plasma sources are examined: a recombining jet of plasma torch, an atmospheric pressure glow discharge, a surface ionized wave device and a gliding arc. The temperatures of these weakly ionized plasmas, measured from the OH spectra, are in good agreement with temperatures obtained by using other techniques: thermocouples, tungsten wire resistance measurements and other spectroscopic methods. The results show that the OH spectra are very useful for temperature measurements of non-equilibrium plasmas.


International Journal of Hydrogen Energy | 1994

Electrically assisted partial oxidation of methane

H. Lesueur; Albin Czernichowski; J. Chapelle

Abstract CO + H 2 synthesis gas is easily obtained from CH 4 + CO 2 mixtures in a new plasma reactor based on gliding discharges (GlidArc) at atmospheric pressure with a high efficiency. Preliminary trials performed in a laboratory reactor at 1.8–4.7 m 3 h −1 gas flow, CO 2 /CH 4 molar ratio of 0.55, 1.13 and 2.17, and up to 3 kW electric power are described. Results are compared with previous results obtained in a controlled arc.


Journal of Physics D | 1996

Application of the (0,0) Swan band spectrum for temperature measurements

Stéphane Pellerin; Karol Musiol; O. Motret; B Pokrzywka; J. Chapelle

Emission spectra of the 516.611 nm Swan band of the molecule were employed for evaluation of the rotational temperature in different plasma sources. This diagnostic method may be applied in the temperature range from 300 - 6000 K and is especially useful for noisy and spectrally not well-resolved spectra when the apparatus function of a recording system is unknown. The described method is based on a comparison of experimental data with the theoretically calculated spectrum. The numerical minimization procedure is started with the temperature value obtained from the Boltzmann plot or the intensity ratio of two selected spectrum components. An analysis of a theoretically calculated spectrum is presented. Two plasma sources were examined, a plasma torch recombining jet and high-voltage-triggered dielectric barrier discharge (DBD).


Journal of Physics D | 1994

Investigation of a cathode region of an electric arc

Stéphane Pellerin; Karol Musiol; B. Pokrzywka; J. Chapelle

Investigations of the near-cathode region of the atmospheric pressure, 200 A arc burning in pure argon have been performed using spectroscopic techniques. Several slices at different distances from the cathode tip have been observed side-on. In order to perform diagnostic measurements of the plasma, the profiles of the Ar I and Ar II lines have been recorded. Phenomena inexplicable in terms of the model based on assumption of a local thermodynamic equilibrium state and constant pressure in the plasma have been observed and are shown on an Olsen-Richter diagram.


Journal of Physics D | 2004

Diagnostic by emission spectroscopy of an argon–hydrogen RF inductive thermal plasma for purification of metallurgical grade silicon

M Benmansour; M Nikravech; Daniel Morvan; Jacques Amouroux; J. Chapelle

Purification of metallurgical grade silicon is one of the methods used to produce photovoltaic grade silicon. In our study, particles of metallurgical grade silicon were purified using a hydrogenated argon thermal plasma. During their residence time in the plasma, the particles were purified by partial evaporation and then sprayed into liquid droplets on the surface of a ceramic substrate. The in-flight purification of powder depends essentially on their evaporation rate, which is directly related to the temperature and chemical properties of the plasma zones crossed by the particles. It was, therefore, important to characterize the plasma parameters: electron density and temperature profiles. Excited states of atomic hydrogen, neutral and ionized silicon and impurity lines were detected in the plasma flow. Those lines were then used to estimate the electron density and temperature, which are around 2.4 × 1016 cm−3 and 10 500 K in the inductive zone. Finally, we estimate the silicon evaporated fraction X of the particles during their thermal treatment in the hydrogenated argon plasma. The results show that the loss of mass is weak (X = 2.5 × 10−4) but nevertheless sufficient for the elimination of the superficial impurities in the powders. This conclusion was confirmed by inductively coupled plasma analyses.


Journal of Physics B | 1996

Stark width of - Ar I transition (696.543 nm)

Stéphane Pellerin; Karol Musiol; B. Pokrzywka; J. Chapelle

The full width at half maximum (FWHM) of the 696.5 nm Ar I spectral line profiles was measured in the plasma temperature range from 13 500 K to 24 000 K and free electron density from 1.2 to . Results were obtained for this line emitted from the near-cathode region of an atmospheric pressure, 200 A arc burning in pure argon. Our results are compared with data existing up to now. In the electron density range of our experiment, the 696.543 nm Ar I line Stark FWHM is linearly proportional to the electron density. The observed dependence of the FWHM on the plasma temperature and electron density is in qualitative agreement with Griems theory; however, the ratio of calculated and measured FWHM was equal to 1.55, for the dependence on electron density and temperature. The dependence of FWHM on electron density, obtained by weighted least squares fitting of all our data with the constraint that the curve passes through the origin, is well represented by the following equation: , with in nm and in , for the temperature .


Journal of Physics D | 1996

Spectroscopic investigation of the equilibrium state in the electric arc cathode region

B. Pokrzywka; Karol Musiol; Stéphane Pellerin; E. Pawelec; J. Chapelle

Several thin layers of an arc plasma column were observed side-on at different distances from the cathode. The arc was operated in argon at atmospheric pressure with the arc current equal to 200 A. As the basic diagnostic method we used the Olsen - Richter diagrams. For determination of temperature the Larenz - Fowler - Milne and Boltzmann plot methods were applied. Electron density was measured from the Stark width of the ArII line and continuum intensity. The plasma near the cathode tip shows axial and radial dependence of its physical equilibrium state. In the hot core, the plasma is in LTE. Toward outer zones, the plasma state deviates from LTE. For plasma layers closer to the cathode, this deviation begins at smaller distances from the axis and for higher temperatures it vanishes for h > 3 mm. It is caused after all by the ArI ground state overpopulation. Theoretical estimations of the ArI ground state overpopulation give results consistent with experiment. Calculations show that this overpopulation is caused by inward transport of ground state atoms into the plasma column.


Journal of Quantitative Spectroscopy & Radiative Transfer | 1985

Use of the 447 nm He I line to determine electron concentrations

Albin Czernichowski; J. Chapelle

Abstract The helium 447 nm complex line has been excited in a wall-stabilized arc fed at atmospheric pressure by pure He, He-H 2 , He-Ne-H 2 or He-Ar-H 2 mixtures. Photoelectric endon observations of the central part of the arc channel were made with high spatial (1/600) and spectral (53,000) resolution. A collection of 88 helium 447 nm line profiles, of which 75 were recorded simultaneously with H β and Ne I or Ar II line profiles, yielded information about the electron concentration (2 X 10 20 -2 X 10 22 m -3 ), temperature and relative ion composition of the plasma. Plots have been made of the forbidden to allowed peak separations ( S ), forbidden to allowed relative intensities of the peaks ( F/A ) and dips (i.e. the minimum intensities between lines) to allowed peak intensities ( D/A ) as functions of electron concentration, temperature and ionic composition in different plasmas. The peak separations depend only on the electron concentration. Other characteristic line-profile parameters ( F/A and D/A ) show weak ion motion with a strong electron-concentration influence. We propose simple formulae, which may be useful for practical determinations of the electron concentrations in helium-containing plasmas with an accuracy of ±15% and without taking into account either the chemical composition of the plasma or the temperature.


Journal of Quantitative Spectroscopy & Radiative Transfer | 1997

MEASUREMENT OF ATOMIC PARAMETERS OF SINGLY IONIZED ARGON LINES-III. STARK BROADENING PARAMETERS

Stéphane Pellerin; K. Musiol; J. Chapelle

Abstract In order to observe ArII transitions between levels of high excitation energy, and to have the highest possible temperature and free electron density in the applied light source, we have observed side-on the near-cathode zone of an electric arc of Iarc = 200 A current, burning in pure argon at atmospheric pressure. Spectroscopic diagnostics of the observed zone showed that it was characterized by a high temperature and an electron density of the order T ≈ 24,000 K and Ne ≈ 2 × 1023 m−3, respectively. Altogether, we have registered more than 90 spectral lines from different levels and configurations, for which the upper levels belong to the 4f configuration (excitation energy Er > 24 eV), as well as 5s and 3d″ (Ei > 22 eV). Our data, the transition probabilities and Stark widths of some 90 and 80 ArII lines, respectively, in many cases measured for the first time, are consistent with the best data published up to now and give one of the most complete sets of results. The applied experimental procedure and characteristics of investigated singly ionized argon levels are presented in the first part of this paper. In this third part, we present the results of our measurements of the Stark widths for 80 ArII lines.


Journal of Chemical Physics | 1978

The interactions between excited and ground state rare gas atoms

O. Vallée; J. Glasser; P. Ranson; J. Chapelle

In this paper, we report on a two component potential model. A general formula for the electrostatic part is derived, giving the second order perturbation terms of the multipolar expansion. The first of these terms is the well‐known van der Waals potential. In the second section, we study the repulsive part of the potential using the Smirnov–Roueff potential: this is based on the scattering properties of the optical electron of an excited state atom on a second atom in its ground state. We introduce a correction term which enables one to find a more realistic potential well, even if the scattering length of the atom in its ground state is negative. In a third section, we apply the model to the calculation of the interaction potentials of rare gases in the first excited states, and the Ar, Kr, and Xe atoms in their ground states.

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F. Richard

University of Orléans

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O. Vallée

University of Orléans

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H. Lesueur

University of Orléans

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P. Ranson

University of Orléans

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