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International audience; This paper is devoted to the study of the argon flow modification in a cold atmospheric pressure plasma jet driven by nanosecond high voltage (HV) pulses, from single to multiple HV shots applications. A schlieren optical bench has been designed in order to visualize the argon flow downstream expansion in quiescent air, for moderate flow rates below 1 standard liter per minute. A coupled approach is used between charge coupled device (CCD) schlieren imaging and intensified CCD (ICCD) plasma plume imaging, both time-resolved. It is shown that the application of only one HV pulse (i.e. single HV shot) is enough to disturb the flow. The disturbed flow exhibits ripple propagation, on a timescale similar to the flow velocity. When operating in double HV shots, the second ionization wave can be used as a probe, to instantly visualize the flow structure any time after the first HV pulse application. For some flow rates, the ripple can increase in amplitude up to the point when it strongly deforms, or even stops, the plasma plume expansion, after which it is entrained by the flow and the plasma plume retrieves its full usual expansion. When a series of HV pulses are applied, the maximal disturbance of the flow is achieved for a certain pulse repetition frequency (PRF), specific of each flow rate. It is associated with ripples alternation in the plasma plume, in a 3D helicallike arrangement. For greater PRF, the ripples progressively vanish, and the flow is clearly less disturbed. Once the ripples have vanished, increasing further the PRF does not change the plasma plume and flow structures. We suggest that the repetitive plasma ignition mechanically forces the flow inside the capillary with consequences on the global flow structure, similarly to a forced backward-facing step flow with actuator.

Atmospheric microplasma jets (MPJs) sustained in rare gases have gained increased attention due to their potential to generate highly reactive species. In this paper, we present space- and time-resolved argon metastable densities, Ar(1s5), measured in an atmospheric pressure MPJ operated in Ar and propagating into ambient air using tunable diode laser absorption spectroscopy (1s5 → 2p9 optical transition). The MPJ was produced using a dielectric barrier discharge energized by short duration (230 ns) high-voltage positive pulses (4.2–6.2 kV) at a repetition frequency of 20 kHz. The spectral absorption line profile was recorded and allowed measurements of the absolute metastable Ar(1s5) density integrated in the line-of-sight of the laser beam under various operating conditions of the MPJ. The results reveal a sensitive dependence of the Ar(1s5) density on spatial coordinates, i.e., distance from the exit of the capillary tube of the discharge and from the axis of the argon jet. The highest Ar(1s5) densities of about 3 × 1013 cm−3 were measured at the axis of the argon jet at longitudinal distances between 4 and 5.5 mm downstream from the nozzle of the tube. The temporal distribution of the Ar(1s5) density, which presents three maxima, is thoroughly discussed in this paper. The spatial distribution of the effective Ar(1s5) lifetime (

An array of seven micro-hollow cathode discharges (MHCDs) operating in a N2/Ar mixture and ignited by a nanosecond pulsed high voltage is experimentally characterized in this work. Compared to other non-equilibrium discharges, high electron densities can be obtained with this type of microdischarge, and, thus, a high dissociation degree of the molecules is expected to be achieved. This is particularly suited for nitride deposition, which is the targeted application of this work, given that the atomic nitrogen density is a key parameter for this deposition process. The electrical diagnostics reveal that the energy deposited in the plasma during one voltage pulse increases with the Ar fraction in the gas mixture and the voltage pulse repetition frequency. A small effect of the repetition frequency is observed on the voltage and current characteristics of the discharge, while a significant increase in the amplitude of these two electrical parameters is observed with increasing Ar admixture. Consequently, a higher electron density is expected with increasing Ar fraction in the gas mixture and repetition frequency. Time-integrated optical emission spectroscopy is carried out to identify the excited emissive species in the plasma and to determine the time-averaged vibrational and rotational temperatures. For a discharge operating in pure N2, at a repetition frequency of 40 kHz, the time-averaged rotational temperature is found to be 390 K ± 40 K and the time-averaged vibrational temperature is 3580 K ± 200 K, revealing the non-equilibrium nature of the discharge. Both temperatures increase with the Ar fraction in the N2/Ar mixture, while they are almost independent of the repetition frequency. Finally, the different phases of the spatio-temporal evolution of the discharge are mapped using space-time resolved ICCD images. The spatial evolution of the discharge between two consecutive voltage pulses can be decomposed in four phases, corresponding to the different stages of the temporal evolution of the discharge voltage.

International audience; This work presents spatial (axial-z and transversal-y) and temporal distributions of Ar(1s(5)) metastable absolute densities in an atmospheric pressure argon micro-plasma jet impinging on an ungrounded glass surface. Guided streamers are generated with a DBD device driven by pulsed positive high voltages of 6 kV in amplitude, 224 +/- 3 ns in FWHM and 20 kHz in frequency. The argon flow rate is varied between 200 and 600 sccm. The glass plate is placed at 5 mm away from the reactor's nozzle and perpendicular to the streamers propagation. At these conditions, a diffuse stable discharge is established after the passage of the streamers allowing the quantification of the Ar(1s(5)) absolute density by means of a conventional TDLAS technique coupled with emission spectroscopy and ICCD imaging. The good reproducibility of the absorption signals is demonstrated. The experiments show the strong dependence of the maximum density (0.5-4 x 10(13) cm(-3)) on the gas flow rate and the axial and transversal position. At 200 sccm, high maximum densities (>2.4 x 10(13) cm(-3)) are obtained in a small area close to the plasma source, while with increasing flow rate this area expands towards the glass plate. In the transversal direction, density maxima are obtained in a small zone around the propagation axis of the streamers. Finally, a noticeable increase is measured on the Ar(1s(5)) effective lifetime close to the glass surface by varying the flow rate from 200 to 600 sccm. In overall, the effective lifetime varies between similar to 25 and similar to 550 ns, depending on the gas flow rate and the values of z and y coordinates. The results obtained suggest that the present system can be implemented in various applications and particularly in what concerns the detection of weakly volatile organic compounds present in trace amounts on different surfaces.

International audience; The present work is devoted to the precise spatiotemporal mapping of the absolute density of Ar(1s(5)) in a ns-pulsed argon plasma jet. The plasma impinges on glass and alumina targets at floating potential placed 5mm away from the reactor's nozzle. Under these conditions, diffuse discharges are established in the small gas gap. As so, the line-of-sight absolute density of Ar(1s(5)) is effectively evaluated via laser absorption spectroscopy. The application of the Abel-inversion is also demonstrated for different operating conditions leading to the precise radial mapping of the Ar(1s(5)) absolute density. The influence of each target is studied for two gas flow rates, 0.3 and 0.4lmin(-1). The temporal density profiles over a voltage pulse period reveal two maxima related with the Ar(1s(5)) production in the streamer head and in the residual diffuse plasma channel. Furthermore, the maximum Ar(1s(5)) axial/radial density (approximate to 10(13)-3.5x10(14)cm(-3)) depends on the target material and gas flow rate. Finally, the plasma is proved to be very effective for the fast desorption of organic molecules (bibenzyl) deposited on both targets. The results obtained suggest that the desorption of bibenzyl is due to the production of high Ar(1s(5)) densities at the close vicinity of the targets. [GRAPHICS] .

Cold atmospheric pressure plasmas (CAPPs) have emerged over the last decade as a new promising therapy to fight cancer. CAPPs’ antitumor activity is primarily due to the delivery of reactive oxygen and nitrogen species (RONS), but the precise determination of the constituents linked to this anticancer process remains to be done. In the present study, using a micro-plasma jet produced in helium (He), we demonstrate that the concentration of H2O2, NO2− and NO3− can fully account for the majority of RONS produced in plasma-activated buffer. The role of these species on the viability of normal and tumour cell lines was investigated. Although the degree of sensitivity to H2O2 is cell-type dependent, we show that H2O2 alone cannot account for the toxicity of He plasma. Indeed, NO2−, but not NO3−, acts in synergy with H2O2 to enhance cell death in normal and tumour cell lines to a level similar to that observed after plasma treatment. Our findings suggest that the efficiency of plasma treatment strongly depends on the combination of H2O2 and NO2− in determined concentrations. We also show that the interaction of the He plasma jet with the ambient air is required to generate NO2− and NO3− in solution.

International audience; Using tunable diode laser absorption spectroscopy, the spatio-temporal distributions of the helium He(23 S1) metastable atoms’ density were measured in a plasma jet propagating in ambient air. The plasma jet was produced by applying short duration high voltage pulses on the electrodes of a DBD-like structure, at a repetition rate in the range 1–30 kHz. In addition to the metastable density, the spatial distribution of helium 587 nm emission intensity was also investigated to give insight into the excitation mechanisms of the He(33 D) excited state inside the dielectric tube, in which no laser measurement can be performed. It is demonstrated that the shape of the radial distribution of helium He(23 S1) metastable atoms strongly depends on the polarity of the applied voltage and on the repetition frequency. For positive applied voltages, a dramatic constriction of the excited species production is observed whenever the pulse repetition frequency is higher than 6 kHz, and the voltage higher than 5 kV. This shrinking of the jet structure induces an increase by one order of magnitude of the metastable atoms’ density in the jet centre which reaches values as high as 1014 cm−3. Beyond a critical distance, associated to a transition between a positive streamer and a negative one, the distribution of the excited atoms gets back to an annular structure. For the negative polarity, no shrinking effect correlated to the pulse repetition frequency was observed. The on-axis constriction of the excited species for the high repetition rate and positive polarity is attributed to a memory effect induced by the negative ions, having a lifetime of hundreds of microseconds, left between successive pulses at the periphery of the helium gas flow.

6th Central European Symposium on Plasma Chemistry (CESPC), Bressanone, ITALY, SEP 06-10, 2015; International audience; The propagation of a DC-pulsed argon plasma jet through the surrounding ambient air, and its interaction with an ungrounded glass plate placed on the jet trajectory, was studied by means of fast imaging. The surface plays an important role in the spatio-temporal characteristics of the plasma. Indeed, for an argon jet propagating perpendicularly to the surface, the plasma jet structure changes from filamentary to diffuse when the distance between the nozzle of the capillary tube and the surface is short (

International audience; Because of their capabilities to generate plasmas that are not confined between electrodes, low-temperature plasma jets offer unique opportunities for applications such as material processing and biomedicine. The need to generate multiple jets in order to cover larger treatment areas has recently become desirable. However, the interaction between neighbouringjets is unavoidable. It is therefore crucial to elucidate the physical processes that occur between jets. In this paper we present the case of two counter-propagating jets generated bytwo DBD-based devices. We show that the plasma bullets emitted by the two jets interact with each other as soon as they leave their respective DBD device, resulting in a decrease in their velocities. The bullets do not actually meet but rather approach each other at a minimum approach distance. The location of the region of minimum approach is not midway between the nozzles of the jet devices but rather depends on the operating conditions. In addition, we discovered the emergence of a ‘secondary’ discharge exactly in the region of minimum approach. This discharge exhibits a pink glow, reminiscent of the pink afterglow occurring in some nitrogen discharges. Time-resolved spectroscopic measurements and current measurement analysis showed that the pink glow is a transient negative glow discharge thatcannot be attributed to kinetic processes associated with re-excitation of nitrogen molecules. It is rather ignited by electrons accelerated from both jets towards the region of minimum approach. This process is found to be exactly timed with the measured current reversal.

Fleury Michel. Les découvertes d'époque protohistorique et néolithique faites dans la fouille de l'ancien entrepôt de Bercy (XIIe arrondissement de Paris) en 1991-1992. In: Bulletin de la Société Nationale des Antiquaires de France, 1992, 1994. pp. 53-57.

Cold plasma jets produced by pulsed discharges have recently attracted a lot of attention because of their unusual physical properties enabling the development of new applications, particularly for plasma medicine. ICCD pictures of these jets revealed that they were not continuous plasmas but composed of plasma bullets propagating at very high velocity. In this paper, pictures of the interaction of two counterpropagating bullets have been taken to give insights into the physics of the bullets and to clarify which kind of models could be relevant to describe the bullet properties.

Arrays of microhollow cathode discharges or cathode boundary layer discharges were operated in krypton?chlorine mixtures resulting in an intense ultraviolet emission at 222?nm. It was demonstrated that nanosecond duration pulses applied at high repetition frequency allowed one to simultaneously ignite and sustain discharges inside all the microcavities of the arrays without using any resistive ballast. Self-repelling properties of adjacent plasmas expanding onto the cathode surface for the negative polarity part of the high-voltage pulses were demonstrated, resulting in a self-limitation of the available cathode surface for an individual microdischarge. Spectroscopic investigations allowed us to determine the gas temperature and evolution of the 222?nm band intensity versus the partial pressures and deposited power. Optimum partial pressure ranges for chlorine and krypton were 0.2?0.8?mbar and 50?70?mbar, respectively. The 222?nm band intensity increased linearly with the deposited energy per pulse and the pulse repetition frequency provided that the mean deposited energy was lower than 7?W. Above this value a cooling of the device should be implemented.

Fleury Michel. Nouvelles observations sur le casque ou chapel doré de Charles VI. In: Bulletin de la Société Nationale des Antiquaires de France, 1989, 1991. pp. 141-152.

The Score of Regions in the Creation of Firms - Ile de France and the two mediterranean regions come first in the creation of firms. Franche-Comté, Burgundy and the two Massif Central regions come last. However the most dynamic regions in terms of creation, are often those where firms are least guaranteed to last long. Thus, in Ile de France and the two mediterranean regions, firms have a much lower survival rate than the national average. On the contrary, the firms in Massif Central have the longest lifespans., L'Ile-de-France et les deux régions méditerranéennes détiennent la palme de la création d'entreprises. Aux dernières places, la Franche-Comté, la Bourgogne et les deux régions du Massif Central. Toutefois, les régions les plus «créatrices» sont souvent celles où la longévité des entreprises est la moins assurée. Ainsi, les entreprises ont des taux de survie très inférieurs à la moyenne nationale en Ile-de-France et dans les régions méditerranéennes. A l'inverse, les entreprises du Massif Central sont celles où la longévité des entreprises est la plus élevée., Creación de empresas : regiones galardoneadas - La region Ile-de-France y las dos regiones mediterráneas detentan el galardón de la creación de empresas. En los últimos puestos se encuentran Borgona, Franche-Comté y las dos regiones del Maciso Central. Sin embargo, las regiones más dinámicas en materia de creación son frecuentemente aquellas en las que es mucho menor la longevidad de las firmas. Es así como la tasa de supervivencia de las empresas es muy inferior à la media nacional en Ile-de-France y en las regiones mediterráneas. Inversamente, las empresas situadas en el Macizo Central baten los records de longevidad., Fleury Michel. Les régions au palmarès de la création d'entreprises. In: Economie et statistique, n°215, Novembre 1988. L'évolution de l'emploi et du chômage / Autour de la création d'entreprises. pp. 51-56.

Fleury Michel, Kruta Venceslas. Premiers résultats des fouilles de la Cour carrée du Louvre. In: Comptes rendus des séances de l'Académie des Inscriptions et Belles-Lettres, 129ᵉ année, N. 4, 1985. pp. 649-672.

Fleury Michel, Henry Louis. Pour connaître la population de la France depuis Louis XIV. — Plan de travaux par sondage. In: Population, 13ᵉ année, n°4, 1958. pp. 663-686.

Fleury Michel. Nouvelle campagne de fouilles des sépultures de la basilique de Saint-Denis. In: Comptes rendus des séances de l'Académie des Inscriptions et Belles-Lettres, 102ᵉ année, N. 2, 1958. pp. 137-150.

Fleury Michel. Le bailliage d'Amiens, son ressort et le problème des limites administratives au Moyen Age. In: Bibliothèque de l'école des chartes. 1956, tome 114. pp. 45-59.

Fleury Michel. Notes et documents sur Ferdinand de Saussure (1880-1891). In: École pratique des hautes études. 4e section, Sciences historiques et philologiques. Annuaire 1964-1965. 1964. pp. 35-67.

Fleury Michel. Origines mérovingiennes de l'ancienne église Notre-Dame des Champs de Paris. In: Bulletin de la Société Nationale des Antiquaires de France, 1963, 1965. pp. 23-25.

Fleury Michel. Charles Samaran et le Journal des Savants. In: Journal des savants, 1982, n°1. pp. 3-6.

Fleury Michel. Discours de M. Michel Fleury, président sortant. In: Bulletin de la Société Nationale des Antiquaires de France, 1976, 1978. pp. 11-25.

Boucly Jean Louis. Un fragment inédit de bol signé [C. CINCI S]ENOVI[RI] découvert dans les ruines de l'aqueduc de Bavai, à Saint-Rémy-du-Nord. In: Gallia, tome 35, fascicule 2, 1977. pp. 263-269.

Fleury Michel. Une lettre inédite de Victor Duruy à Edmond About (1868). In: École pratique des hautes études. 4e section, Sciences historiques et philologiques. Annuaire 1966-1967. 1966. pp. 43-48.

Fleury Michel. L'anneau sigillaire d'Arégonde, femme de Clotaire Ier, découvert à Saint-Denis. In: Bulletin de la Société Nationale des Antiquaires de France, 1963, 1965. pp. 34-42.

Fleury Michel. Premiers résultats des fouilles suivies par la Commission du Vieux-Paris de 1955 à 1957. In: Bulletin de la Société Nationale des Antiquaires de France, 1957, 1959. pp. 106-115.

L'importance des recherches historiques en matière démographique a été souvent soulignée dans Population. Une étude de M. J. Bourgeois-Pichat (octobre-décembre 1951 et avril- juin 1952) avait notamment permis de reporter la période statistique, jusqu'au début du règne de Louis XVI. Mais, au-delà de cette période, les relevés statistiques sont si rares et fragmentaires que cette partie fondamentale de l'Histoire est encore très incertaine. M. Louis Henry avait déjà montré (Population avril-juin 1953) la richesse inexploitée que constituent les registres paroissiaux. Comme le dépouillement de ces registres à des fins démographiques soulève des difficultés techniques, il a rédigé, avec l'aide de M. Michel Fleury, archiviste-adjoint du département de la Seine et de la Ville de Paris, un manuel à l'intention des nombreux chercheurs qui travaillent sur les registres paroissiaux. Ce manuel, d'une utilité considérable, était impatiemment attendu. Les auteurs présentent ici leur ouvrage, en cours de publù cation par l'I.N.E.D., Fleury Michel, Henry Louis. Des registres paroissiaux à l'histoire de la population : manuel de dépouillement et d'exploitation de l'état civil ancien - Présentation d'une publication de l'I.N.E.D. In: Population, 11ᵉ année, n°1, 1956. pp. 142-144.

L'histoire de la population française ne s'appuie que depuis la fin du xvnie siècle sur des statistiques régulières. Celles-ci, rassemblées et ajustées par J. Bourgeois-Pichat, ont permis de retracer, depuis 1776, l'évolution générale de la population par groupes d'âge et périodes quinquennales (1). Avant cette date, on ne dispose que de renseignements fragmentaires et de qualité souvent incertaine. Les documents de base existent cependant, du moins en grande partie; ce sont les registres paroissiaux, dont certains remontent même avant l'édit de Villers-Cotterêts de François Ie1. MM. Michel Fleury et Louis Henry ont entrepris un vaste travail visant l'exploitation de ces documents, qui avaient longtemps servi beaucoup plus à des recherches de généalogie qu'à des travaux démographiques. En 1956, ils publiaient à l'I.N.E.D. un petit manuel sur l'utilisation des registres paroissiaux à des fins statistiques (2). Il a été suivi d'applications soit à l'I.N.E.D., soit à l'extérieur, par des élèves de MM. Gode- chot, Merlier, Mousnier, Portal, Reinhard et Trènard. L'I.N.E.D. a publié le travail de MM. Etienne Gautier et Louis Henry sur Crulai{3) et celui de M. Pierre Girard sur Sotteville-lès-Rouenw. Un autre a paru ailleurs^. De son côté, M. Pierre Goubert a utilisé très tôt et largement les registres paroissiaux^, en particulier pour sa thèse sur « Beauvais et le Beauvaisis de 1600 à 1730» dont un compte rendu a paru dans Population (7). Ces essais ne faisaient pas oublier la nécessité de jeter les bases d'une enquête systématique. MM. Michel Fleury et Louis Henry ont établi un plan de travaux par sondage (1), comportant en particulier l'établissement d'un échantillon de communes, puis d'un échantillon de documents. Une première étape consistait à connaître l'état de la documentation disponible. Ce fut le travail de ces derniers mois, entrepris avec la précieuse collaboration des Archives de France. Ce travail important qui exigera de longs efforts nécessite une collaboration étroite entre statisticiens et archivistes, entre démographes et historiens; commencé sous d'heureux auspices, grâce à la compréhension des Archives de France, il doit se poursuivre dans les années qui viennent et placer notre pays au premier rang de ceux qui cherchent à connaître l'histoire de leur population. Nous tenons à remercier tout particulièrement les Directeurs des services d'archives des départements et les Archivistes municipaux qui ont bien voulu nous aider dans notre enquête et se sont parfois livrés à des recherches longues et approfondies pour satisfaire nos demandes : MM. Paul Aimés, Robert Allain, Robert Avezou, Edouard Baratier, Pierre Bayaud, Noël Becquart, Henri de Berranger, Paul Berthier, André Betgé-Brezetz, Mlle Françoise Bibolet, MM. Joseph Billioud, François Blanchet, Henri Blaquière, Xavier du Boisrouvray, Pierre Bougard, Jacques Bousquet, MUe Léonce Bouyssou, MM. Laurent Boyer, François Burckard, Jean-Marie Burias, Henri Chanteux, Henri Charnier, Mlle Odile Colin, MM. Raymond Collier, Jean Colnat, Jean Courtieu, Robert Debant, Jacques Decanter, Marcel Delafosse, Etienne Delcambre, Philippe Dollinger, Jacques Dropet, Gustave Duhem, Georges Dumas, Jean-Marie Dumont, Mlle Jeanne Dupic, MM. Jean Estienne, Jacques de Font-Réaulx, Henri Forestier, Foucher, Robert de Fournoux, Bernard de Gaulejac, Jean Gou- rhand, Marcel Gouron, Granet, Maurice Greslé-Bouignol, Mme Marie-Josèphe Gut, MM. Henri Hemmer, Pierre d'Herbe- court, Ernest Hildesheimer, François Himly, Bernard Jarry, Jenny, Mme Alice Joly, MM. René Lacour, Pierre Lamotte,MUe Marie- Josèphe Lecacheux, MM. Bernard Lemée, Michel Le Pesant, Charles Lerch, Jacques Letrait, Jacques Levron, Joseph Mangin, Jean Martin-Demézil, Mathieu Méras, Louis Monnier, Arthur Morgand, Yves Nédelec, Raymond Our sel, André Perret, Yves Pérotin, J. Pieters, René Prat, Jean Quéguiner, Jacques Riche, Jean Rigault, René Robinet, MUe Armance Royer, MM. Jean Sablou, Odon de Saint-Blanquat, Mlle Simone de Saint-Exupéry, MM. Régis de Saint-Jouan, Bernard Savouret, Roger Sève, Etienne Taillemite, Pierre Thilliez, Pierre Thomas-Lacroix, Robert Tinthoin, Henri Tribout de \Morembert, Xavier Vedere, François Villard, Jean Waquet, Christian Wilsdorf, Biraben Jean-Noël, Henry Louis, Fleury Michel. Inventaire par sondage des registres paroissiaux de France. In: Population, 15ᵉ année, n°1, 1960. pp. 25-58.

Fleury Michel. Seine. — Les sculptures de Notre-Dame de Paris découvertes. In: Bulletin Monumental, tome 135, n°2, année 1977. pp. 160-161.

L'importance des recherches historiques en matiere demographique a ete souvent soulignee dans Population. Une etude de M. J. Bourgeois-Pichat (octobre-decembre 1951 et avril- juin 1952) avait notamment permis de reporter la periode statistique, jusqu'au debut du regne de Louis XVI. Mais, au-dela de cette periode, les releves statistiques sont si rares et fragmentaires que cette partie fondamentale de l'Histoire est encore tres incertaine. M. Louis Henry avait deja montre (Population avril-juin 1953) la richesse inexploitee que constituent les registres paroissiaux. Comme le depouillement de ces registres a des fins demographiques souleve des difficultes techniques, il a redige, avec l'aide de M. Michel Fleury, archiviste-adjoint du departement de la Seine et de la Ville de Paris, un manuel a l'intention des nombreux chercheurs qui travaillent sur les registres paroissiaux. Ce manuel, d'une utilite considerable, etait impatiemment attendu. Les auteurs presentent ici leur ouvrage, en cours de publu cation par l'I.N.E.D.