S. Pellerin - Academia.edu (original) (raw)

Papers by S. Pellerin

2019 International Conference on Electromechanical and Energy Systems (SIELMEN)

This paper presents an analysis of the influence of different parameters on energy efficiency of ... more This paper presents an analysis of the influence of different parameters on energy efficiency of a spray, point-to-point, non-thermal plasma (NTP) reactor in plasma activated water generation. The polarity of the DC pulse power supply is assessed for different input parameters such the frequency (60, 150 and 250 Hz), water flowrate (5, 10, 15 and 20 mL/min) and gas flowrate (1 and 2 L/min Ar). There are also presented the values of important electrical parameters of the plasma such the average power or discharge energy. The concentration of hydrogen peroxide generated into plasma activated water was considered as indicator of the energy efficiency.

Journal of Applied Physics

Plasma activated water is a chemically active aqueous medium characterized by the presence of rea... more Plasma activated water is a chemically active aqueous medium characterized by the presence of reactive oxygen and nitrogen species created by plasma exposure. This particular chemical composition is the starting point of extensive research studies in several domains such as bio-disinfectant in biomedical applications or as fertilizer in agricultural applications. These various applications need adjustments of the PAW properties and consequently require a better control of the PAW chemical composition. To achieve this aim, a UV spectrophotometric method (190–255 nm) is implemented to simultaneously detect the nitrate and nitrite ions in plasma activated water by a gliding arc discharge reactor at atmospheric pressure. The method, tested in plasma activated distilled water (PADW) and in plasma activated tap water (PATW), shows significant increases of nitrite and nitrate concentrations. Preliminary results on PADW and PATW kinetics evolutions highlight a different behavior of the temporal post-discharge reactions leading to non-conversion of the nitrite ions in the case of PATW. The near non-existence of acidification during and after plasma activation encountered in PATW is due to high levels of carbonate species in tap water acting as a buffer solution. Indeed, the presence of hydrogen carbonate (HCO3−) leads to the acidity consumption during plasma activation whereas the presence of non-dissolved limestone in hard water (CaCO3) acts as carbonates reserve, and this induces the acidity consumption after plasma treatment.

AIP Conference Proceedings, 2006

The type of the applied shielding gas has a strong influence on quality of the welding process. I... more The type of the applied shielding gas has a strong influence on quality of the welding process. In particular, increase of the percentage of carbon dioxide in argon, causes increase of the transition current value from the globular to spray mode of metal transfer. Observations by fast camera allows to better characterize the arc column shape in the different working modes. The spectroscopic diagnostic of the welding arc is also necessary to understand the observed changes in the mode of droplet transfer. The use of an original diagnostic method allows to estimate the temperature and the electronic density distributions in the plasma without hypothesis on its equilibrium state. Results of this work seem to show that the observed effects could be linked to the microstructural modifications of the anode tip during the MIG-MAG welding process as a function of the gas composition, and especially to the existence and disappearance of an insulating oxide ``gangue'' at the wire extremity.

P 4 PCTAS -Air Liquide Welding, Saint Ouen l'Aumone, 95315 Cergy-Pontoise cedex -France For a... more P 4 PCTAS -Air Liquide Welding, Saint Ouen l'Aumone, 95315 Cergy-Pontoise cedex -France For arc welding process analysis, detailed information on both the distribution of energy flow and excess pressure at the weld pool surface is needed. Numerical arc modelling can deliver such information. Through simultaneous solutions of the set of conservation equations for mass, momentum, energy and current, a mathematical model has been developed to predict the velocity, temperature and current density distribution in gas tungsten arc welding (GTAW). The model could lay the foundation for developing a comprehensive model of the gas metal arc welding (GMAW) by using spectroscopic measurements of electronic temperature and density as reference data. High-speed images acquisition shows complex dynamic processes of droplet formation due to the forces acting on the molten metal. Most of these forces change as function of time depending on factors including instantaneous electrode configuration...

Journal of Optoelectronics and Advanced Materials

The dielectric wall surfaces of the annular chamber which are used in Hall Effect Thrusters (HET)... more The dielectric wall surfaces of the annular chamber which are used in Hall Effect Thrusters (HET) to limit the plasma discharge play an important role but yet completely not understood and controlled. In order to investigate the effect of an energy flux on the wall we performed tests with a nanosecond pulsed laser to simulate the energy deposition on BNSiO 2 (usual dielectric material for HETs). The tests have been carried out with the second harmonic (532 nm) of a Q-switched (10 ns) Nd:YAG laser focused on the samples placed in a vacuum chamber (10 -6 Torr). The energy/pulse range explored has been 5 – 320 mJ, leading to fluences of 1 – 1000 J/cm 2 . The modifications induced by laser irradiation on the BNSiO 2 targets have been analysed by profilometry and scanning electron microscopy. The plasma created by laser ablation has also been characterized by optical and spectral methods. The present paper presents preliminary results of these combined investigations.

Annales de physique, 1997

Le travail présenté ici concerne une mesure spectroscopique de la température rotationnelle du ra... more Le travail présenté ici concerne une mesure spectroscopique de la température rotationnelle du radical hydroxyl dans un plasma atmosphérique d'aigon-vapeur d'eau. Cette étude est réalisée à partir de la fluorescence UV des niveaux rotationnels 'OH(A, v=0). Le plasma est généré par une Décharge à Barrière Diélectrique déclenchée THT présentant des fronts de montée en tension très abrupts (>10 12 V/s). La température rotationnelle de ces niveaux a été estimée à une valeur très basse (= 300 K). Une comparaison avec des specUes synthétiques présente un très bon accord.

Proceedings of the 6th International Conference on Optimization of Electrical and Electronic Equipments, 1998

ABSTRACT

2012 13th International Conference on Optimization of Electrical and Electronic Equipment (OPTIM), 2012

ABSTRACT To improve the combustion process of the air-fuel mixture into the combustion chamber of... more ABSTRACT To improve the combustion process of the air-fuel mixture into the combustion chamber of the engines, an ignition system based on a three electrodes spark-plug and a microcontroller based supply has been proposed. The benefits which can be achieved by using the new system are: reduction the amount of some pollutants such as unburned hydrocarbons from the exhaust gases, improving the engine's efficiency, fuel consumption decreasing and also some unwanted engine processes (misfires, hesitations, detonations, stutters and stumbles) can be avoided. The first phase of the validation process of the new ignition system was to perform a diagnosis of the plasma produced using the new spark plug and to compare the results with the ones obtained from the diagnosis of the plasma produced by a classical spark plug. Also the electrical parameters were measured for both the spark plugs and for different waveforms of the control signals. In this paper we present a correlation between the rotational temperatures of the plasma and the energy consumed by the discharges produced using the classical and the double spark plugs. The spectra used to determine the rotational temperatures have been recorded in air at atmospheric pressure using a spectrometer equipped with a CCD camera. The electrical discharge voltage and current measurement used to calculate the energy of the discharge have been made in air using a high voltage probe and a shunt resistance.

2014 International Conference on Optimization of Electrical and Electronic Equipment (OPTIM), 2014

Because the spark produced by the classic spark plug does not always ensure complete and efficien... more Because the spark produced by the classic spark plug does not always ensure complete and efficient combustion, there have been proposed various other types of sparks for internal combustion engine. Among these different technical solutions have been found to be effective: pulsed LASER ignition, system with multi ignition points, electrical Corona or GlidArc discharges, multi-electrodes plug, developped by Bosch, pulse jet combustor etc. These ignition systems have tried to find a more efficient electrical discharge for ignition, ensuring combustion in a shorter time, produced into a bigger plasma volume being as homogeneous as possible. We propose an ignition system with a double spark, see Fig. 1. This is achieved by placing between the high voltage electrode and the ground one, of a third unpowered electrode, having floating potential, with the shape of a washer. The dual spark plug leads to a significant volume of plasma in relation to the classic spark, see Fig. 2. This supposes the development of combustion at a lower value of the electrical current, so at a lower temperature of plasma spark, [1]. The validation of this type of plug by the chemical results corresponding to a better combustion, involves optimizing its construction in terms of breakdown of the double spark, using the optimal positioning of the auxiliary electrode. In view of this optimization is calculated the equivalence capacity of the double plug, before the initiation, relative to the vertical distance between the high voltage electrode and the ground electrode. Parametric value of the capacity is introduced into an electrical schema similar to the classic spark ignition model, [2], [3]. The schema has been simulated by using MULTISIM software. The simulated voltage characteristic was compared to the real voltage waveform, experimentally obtained from a spark discharge by using a high voltage probe (1:1000) and an oscilloscope LeCroy WaveSurfer 64MXs-A type (600 MHz, 5 GS/s).

2010 12th International Conference on Optimization of Electrical and Electronic Equipment, 2010

The ignition sparks provided by the classical system do not always assure a fast and complete com... more The ignition sparks provided by the classical system do not always assure a fast and complete combustion of the hydrocarbon-air mixture. For this reason have been made a lot of studies, most of them trying to implement new types of electronic ignition systems, including power supply and the spark plug itself, which must provide faster, more complete and more efficient-fuel

Plasma processing of a (CH 4 + CO 2) mixture can lead to the formation of synthesis gas (CO + H 2... more Plasma processing of a (CH 4 + CO 2) mixture can lead to the formation of synthesis gas (CO + H 2). The use of a nonthermal plasma for this type of process seems very promising. We report here an electric and spectroscopic characteristic of plasma created in a (CH 4 +CO 2) mixture by a high-voltage, steep front-voltage (>10 12 V/s), very-short-pulse triggered dielectric barrier discharge in a tubular cell. Particular attention was payed to the determination of the rotational temperature for C 2. Time resolved investigation of the Swan band leads to an estimated value around 3000 K.

International Journal of Applied Ceramic Technology, 2014

ABSTRACT The Zerodur® glass-ceramic chemical durability has been studied by leaching. The nuclear... more ABSTRACT The Zerodur® glass-ceramic chemical durability has been studied by leaching. The nuclear magnetic resonance spectroscopy analysis has allowed highlighting the network changes. A macroscopic evaluation of the surface alteration has been performed by contact angle measurements, this analysis being sensible to the roughness and the hydrophilic character. In basic solutions, depolymerization phenomena concern all former cations, as result of hydrolysis phenomena. A preferential attack of the interface matrix-nanocrystals, implicating phosphorus involves some nanocrystals removing. The Zerodur® glass-ceramic keeps an excellent chemical durability during exposition to acidic aqueous solutions. But in basic medium, the biphasic nature involves a strong alteration.

Spectrochimica Acta Part B: Atomic Spectroscopy, 2012

ABSTRACT Hall Effect Thrusters (HETs) are promising electric propulsion devices for the station-k... more ABSTRACT Hall Effect Thrusters (HETs) are promising electric propulsion devices for the station-keeping of geostationary satellites and for interplanetary missions. The main limiting factor of the HET lifetime is the erosion of the annular channel ceramic walls. Erosion monitoring has been performed in the laboratory using optical emission spectroscopy (OES) measurements and data treatment based on the coronal model and the actinometric hypothesis. This study uses laser ablation of the ceramic wall in a running HET in order to introduce controlled amounts of sputtered material in the thruster plasma. The transient laser-induced breakdown plasma expands orthogonally in a steady-state plasma jet created by the HET discharge. The proposed spectroscopic method involves species from both plasmas (B, Xe, Xe+). The optical emission signal is correlated to the ablated volume (measured by profilometry) leading to the first direct validation of the actinometric hypothesis in this frame and opening the road for calibration of in-flight erosion monitoring based on the OES method.

Fifth Workshop on Atomic and Molecular Physics, 2005

We investigated laser-based spectroscopic techniques: phase-conjugate degenerate four-wave mixing... more We investigated laser-based spectroscopic techniques: phase-conjugate degenerate four-wave mixing (PC-DFWM) and laser Thomson scattering (LTS) in terms of their application to Stark profile studies in thermal plasma. PC-DFWM was used for the Stark profile determination while LTS served for plasma diagnostic purpose. Experiments were performed for thermal plasma generated in the transferred arc and burning in pure argon at atmospheric

Annales De Physique - ANN PHYS PARIS, 1997

Spectrochimica Acta Part B: Atomic Spectroscopy, 2011

The Thomson scattering method was applied to quantify the electron number density and temperature... more The Thomson scattering method was applied to quantify the electron number density and temperature of a laser spark formed in argon. The laser spark was generated by focusing a 15 mJ beam from the second harmonic (λ L = 532 nm) of a nanosecond Nd:YAG laser with an 80 mm focal length lens. Images of the spark emission were obtained for times between 1 ns and 20 μs after the laser pulse in order to characterize its spatial evolution. The electron density and temperature for the core of the plasma plume at different instants of its evolution were determined from the Thomson scattered spectra of another nanosecond Nd:YAG laser (532 nm, 10 to 60 mJ/pulse). In the time interval between 400 ns and 10 μs between the laser induced plasma and Thomson scattering probe pulses, we found n e and T e to decrease from 4.3 × 10 23 m − 3 to 2.4 × 10 22 m − 3 and from 50 700 K to 11 100 K, respectively. Special care was paid to the plasma disturbance by the probe laser pulse in Thomson scattering experiments due to absorption of laser photons by electrons through the inverse bremsstrahlung process.

Solar Energy Materials and Solar Cells, 2002

The hydrogenation of silicon deposited on a substrate for photovoltaic applications has been obta... more The hydrogenation of silicon deposited on a substrate for photovoltaic applications has been obtained by a plasma torch. This method shows a great advantage and leads to the improvement of the electronic properties of the material. The hydrogenation of silicon allows the crystallographic defects elimination (dislocations, dangling bonds) which leads to an increase of the diffusion length. In order to understand silicon hydrogenation by RF inductive thermal plasma spraying, a study of the discharge by optical emission spectroscopy (OES) has been undertaken. This study has been compared with the hydrogen content measured by the exodiffusion technique. The detection of highly excited species of atomic and molecular hydrogen proves the specificity of the inductive plasma. Hydrogen emission lines have been used to calculate the electronic density on the plasma axis. Furthermore, the ArI lines were used to calculate the electronic temperature in the plasma. With this information, the deviation from the local thermodynamic equilibrium (LTE) of the plasma has also been estimated.

Science and Technology of Welding and Joining, 2012