Influence of a plasma jet on the hydrodynamics of a helium jet

In this paper, we present a study of the influence of non-equilibrium microplasma jets (“plasma bullets”) on the hydrodynamics of a helium jet operating in open air. The helium jet is produced by a flow of helium through a hollow, cylindrical microdischarge configuration. A plasma jet, triggered by the microdischarge, can propogate in the laminar zone of the helium jet which extends some distance from the exit plane of the microdischarge. We used Schlieren photography to visualize the point of transition from laminar to turbulent regime of the helium jet and the change in the transition point due to the plasma jet for different operating conditions

Controlling the nitric and nitrous oxide production of an atmospheric pressure plasma jet-/title-

International audienceAtmospheric pressure plasma jets are non-thermal plasmas and have the ability to create reactive species. These features make it a very attractive tool for biomedi-cal applications. In this work, we studied NO and N 2 O production, which are two species having biomedical properties. NO plays a role in the vascularization and in ulcer treatment, while N 2 O is used as anesthetic and analgesic gas. In this study, the plasma source is similar to the COST Reference Microplasma Jet (–APPJ). Helium is used as feed gas with small admixtures of molecular nitrogen and oxygen of below 1%. The absolute densities of NO and N 2 O were measured in the effluent of an atmospheric pressure RF plasma jet by means of ex-situ quantum-cascade laser absorption spectroscopy via a multi-pass cell in Herriot configuration. We will show that the species' production is dependent on several parameters such as power, flow and oxygen and nitrogen admixture. The NO and N 2 O densities are strongly dependent on the N 2-O 2 ratio. Changing this ratio allows for choosing between a NO-rich or a N 2 O-rich regime [1]. [1] Douat et al, PSST, 25 (2016) 02502

Atmospheric pressure plasma as CO source for biomedical applications

International audienceIn this work we developed a plasma source based on a Plasma Gun reactor able to generate small quantities of CO. The production fraction of CO molecules has been measured ex-situ by means of gas chromatography. We showed that the density is in the 100-10000 ppm range. The CO concentration can be controlled by varying the gas mixture and by tuning the applied voltage. In CO clinical application, the typical dose used is in the range of 100-1000 ppm. It means that this plasma reactor is suitable as CO source for biological applications

Electric field characterization of plasma gun and multi-jet plasma arrays

Invited oralInternational audienceRoom temperature Pulsed Atmospheric Plasma Streams (PAPS) have already demonstrated their unique potential in biology and medicine. Lately, the validation of multi-jet plasmas resulting from metallic and dielectric assemblies-containing many orifices-plugged to a single Plasma Gun (PG) and operating at moderate feed gas flow rate (from hundreds to thousands standard cubic centimeters) has been demonstrated [1]. This technological improvement enhances the credibility of plasma jets to treat large areas and volumes being beneficial in biomedical and recently in agriculture applications. Although the role of reactive oxygen and nitrogen species (RONS) produced by plasma is currently under many investigations, the simultaneous contribution of intense pulsed electric fields (EF) in the activation of biological mechanisms still remains unclear. Therefore, in this work, the authors focus on the characterization of EF in PAPS applied to the treatment of cells and culture medium. EF maps [2] time and space resolved have been recorded with an electro optic sensors [3] and contribute to the interpretation of biological responses, e.g. electroporation, electropermeabilization and the impacts on cell viability. The controlled propagation of multi-jet plasmas depends on the nature of the assemblies and is observed by time resolved iCCD imaging as shown in Fig. 1 and Fig. 2. While the metallic one allows for simultaneous ignitions of multiple PAPS, the dielectric one leads to a controlled splitting of the PG ionization wave, inducing a propagation delay between each orifice. Effects of multi-jet plasmas on the hydrodynamic of the gas are studied together via fast-schlieren imaging and by EF characterization. The outcome of this work will be of significant interest towards the use of multiple jets in plasma treated cells, agriculture and biomedical applications. XD is supported with the grant INEL/Région Centre Val de Loire

Etude d’un micro-jet de plasma à pression atmosphérique

Micro plasma jets operating at atmospheric pressure in free atmosphere have recently attracted great attention because of their numerous advantages. In fact, micro plasma jets can be operated stably at atmospheric pressure and propagated over some centimeters in a free atmosphere. Moreover, these jets are non-thermal plasmas and create numerous reactive species. These properties allow to use this kind of plasma in many applications, such as surface treatment, decontamination, and plasma medicine.In this work it is shown that these micro plasma jets correspond to the fast propagation of an ionization front with no displacement of matter. A characterization of the plasma proprieties (e.g. distance and velocity of propagation) has been done as a function of the applied voltage, gas flow, gas composition and discharge geometry. The spatiotemporal distribution of the reactive species created by the plasma has been measured, with a special focus on the helium metastable atoms which have been measured by absorption laser spectroscopy. The helium metastable atom densities obtained are in the range of 1.10¹² to 5.10¹³ cm-³. Thanks to a very good spatiotemporal resolution, we have done a time-resolved full cartography of the plasma. This allowed us to show that the helium metastable atom distribution is annular near the nozzle and becomes circular as the plasma propagates. The maximum helium metastable atoms density has been measured at about half of the distance where the helium metastable atoms are present. This observation is in contradiction with results reported by numerical models. To gain further insight into the physical processes of the plasma, we have placed two micro plasma jets face to face. This study showed that both plasmas interact in such a way that they never come into contact, letting a space free of plasma between them. Moreover, we revealed that after the extinction of the plasmas, a second discharge is ignited in the previously free space. Fast imaging, spectroscopy diagnostics and electrical measurements showed that this second discharge is due to a polarity reversal, which creates an electron trap. Aiming the study of the application of micro plasma jets in the plasma medicine field, we have studied the degradation of plasmid DNA by our plasma jet. We observed that the plasma treatment leads mostly to single and double strands breaks, and to very little base oxidation and abasite site, even when oxygen is added into the gas mixture.Ces dernières années un nouveau type de décharges hors équilibre thermodynamique, aptes à générer des micro jets de plasma se propageant en atmosphère libre, a suscité beaucoup d’intérêt dans la communauté scientifique. Ces micro jets, produits dans des structures type décharge à barrière diélectrique, ont des propriétés particulièrement intéressantes, tant sur le plan de la physique des plasmas que sur celui des applications, en particulier pour des applications biomédicales ou de traitement de surface.Dans ce travail de thèse il est démontré que ces jets de plasma correspondent à la propagation à grande vitesse d'un front d'ionisation sans déplacement de matière. Une caractérisation des propriétés des jets (vitesse et distance de propagation) a été effectuée en fonction de la tension appliquée, du débit, de la composition du gaz, et de la géométrie de la décharge. La distribution spatio-temporelle des espèces réactives produites par le jet a été mesurée, et en particulier celle de l'état métastable He (2³S) mesuré par absorption laser. Des densités comprises entre 1.10¹² et 5.10¹³ cm-³ ont été obtenues pour l’état He (2³S). Sa distribution est annulaire à la sortie de la structure de la décharge et se referme le long du jet. La densité maximale est obtenue à une distance correspondant à la moitié de la zone où les atomes métastables sont présents, ce qui est en contradiction avec les modèles actuels. De plus, afin de mieux comprendre la physique des jets de plasma, nous avons fait interagir deux jets placés l’un en face de l’autre. L'étude de la contre propagation de deux jets révèle qu’il existe une distance minimale d'approche laissant entre eux une zone exempte de plasma. Après l’extinction des deux plasmas, une seconde décharge s’amorce exactement dans cette zone. Une étude détaillée couplant diagnostics électrique, imagerie ultra-rapide et spectroscopie d'émission nous a permis de montrer que cette décharge secondaire est due à une inversion de polarité conduisant à la création transitoire d'un piège à électrons.Dans le but d'aborder l'étude des applications des jets de plasma au domaine biologique, nous avons également étudié la dégradation de l’ADN plasmidique par un jet de plasma. Nous avons mis en évidence que ce type de plasma induit majoritairement des cassures simples et doubles brins, alors que très peu d’oxydations de base ou de sites abasiques sont observés, ceci même avec l’ajout de quelques pourcents d’oxygène dans le gaz

Study of a cold atmospheric pressure plasma micro jet

Ces dernières années un nouveau type de décharges hors équilibre thermodynamique, aptes à générer des micro jets de plasma se propageant en atmosphère libre, a suscité beaucoup d’intérêt dans la communauté scientifique. Ces micro jets, produits dans des structures type décharge à barrière diélectrique, ont des propriétés particulièrement intéressantes, tant sur le plan de la physique des plasmas que sur celui des applications, en particulier pour des applications biomédicales ou de traitement de surface.Dans ce travail de thèse il est démontré que ces jets de plasma correspondent à la propagation à grande vitesse d'un front d'ionisation sans déplacement de matière. Une caractérisation des propriétés des jets (vitesse et distance de propagation) a été effectuée en fonction de la tension appliquée, du débit, de la composition du gaz, et de la géométrie de la décharge. La distribution spatio-temporelle des espèces réactives produites par le jet a été mesurée, et en particulier celle de l'état métastable He (2³S) mesuré par absorption laser. Des densités comprises entre 1.10¹² et 5.10¹³ cm-³ ont été obtenues pour l’état He (2³S). Sa distribution est annulaire à la sortie de la structure de la décharge et se referme le long du jet. La densité maximale est obtenue à une distance correspondant à la moitié de la zone où les atomes métastables sont présents, ce qui est en contradiction avec les modèles actuels. De plus, afin de mieux comprendre la physique des jets de plasma, nous avons fait interagir deux jets placés l’un en face de l’autre. L'étude de la contre propagation de deux jets révèle qu’il existe une distance minimale d'approche laissant entre eux une zone exempte de plasma. Après l’extinction des deux plasmas, une seconde décharge s’amorce exactement dans cette zone. Une étude détaillée couplant diagnostics électrique, imagerie ultra-rapide et spectroscopie d'émission nous a permis de montrer que cette décharge secondaire est due à une inversion de polarité conduisant à la création transitoire d'un piège à électrons.Dans le but d'aborder l'étude des applications des jets de plasma au domaine biologique, nous avons également étudié la dégradation de l’ADN plasmidique par un jet de plasma. Nous avons mis en évidence que ce type de plasma induit majoritairement des cassures simples et doubles brins, alors que très peu d’oxydations de base ou de sites abasiques sont observés, ceci même avec l’ajout de quelques pourcents d’oxygène dans le gaz.Micro plasma jets operating at atmospheric pressure in free atmosphere have recently attracted great attention because of their numerous advantages. In fact, micro plasma jets can be operated stably at atmospheric pressure and propagated over some centimeters in a free atmosphere. Moreover, these jets are non-thermal plasmas and create numerous reactive species. These properties allow to use this kind of plasma in many applications, such as surface treatment, decontamination, and plasma medicine.In this work it is shown that these micro plasma jets correspond to the fast propagation of an ionization front with no displacement of matter. A characterization of the plasma proprieties (e.g. distance and velocity of propagation) has been done as a function of the applied voltage, gas flow, gas composition and discharge geometry. The spatiotemporal distribution of the reactive species created by the plasma has been measured, with a special focus on the helium metastable atoms which have been measured by absorption laser spectroscopy. The helium metastable atom densities obtained are in the range of 1.10¹² to 5.10¹³ cm-³. Thanks to a very good spatiotemporal resolution, we have done a time-resolved full cartography of the plasma. This allowed us to show that the helium metastable atom distribution is annular near the nozzle and becomes circular as the plasma propagates. The maximum helium metastable atoms density has been measured at about half of the distance where the helium metastable atoms are present. This observation is in contradiction with results reported by numerical models. To gain further insight into the physical processes of the plasma, we have placed two micro plasma jets face to face. This study showed that both plasmas interact in such a way that they never come into contact, letting a space free of plasma between them. Moreover, we revealed that after the extinction of the plasmas, a second discharge is ignited in the previously free space. Fast imaging, spectroscopy diagnostics and electrical measurements showed that this second discharge is due to a polarity reversal, which creates an electron trap. Aiming the study of the application of micro plasma jets in the plasma medicine field, we have studied the degradation of plasmid DNA by our plasma jet. We observed that the plasma treatment leads mostly to single and double strands breaks, and to very little base oxidation and abasite site, even when oxygen is added into the gas mixture

Etude d'un micro-jet de plasma à pression atmosphérique

Ces dernières années un nouveau type de décharges hors équilibre thermodynamique, aptes à générer des micro jets de plasma se propageant en atmosphère libre, a suscité beaucoup d intérêt dans la communauté scientifique. Ces micro jets, produits dans des structures type décharge à barrière diélectrique, ont des propriétés particulièrement intéressantes, tant sur le plan de la physique des plasmas que sur celui des applications, en particulier pour des applications biomédicales ou de traitement de surface.Dans ce travail de thèse il est démontré que ces jets de plasma correspondent à la propagation à grande vitesse d'un front d'ionisation sans déplacement de matière. Une caractérisation des propriétés des jets (vitesse et distance de propagation) a été effectuée en fonction de la tension appliquée, du débit, de la composition du gaz, et de la géométrie de la décharge. La distribution spatio-temporelle des espèces réactives produites par le jet a été mesurée, et en particulier celle de l'état métastable He (2 S) mesuré par absorption laser. Des densités comprises entre 1.10 et 5.10 cm- ont été obtenues pour l état He (2 S). Sa distribution est annulaire à la sortie de la structure de la décharge et se referme le long du jet. La densité maximale est obtenue à une distance correspondant à la moitié de la zone où les atomes métastables sont présents, ce qui est en contradiction avec les modèles actuels. De plus, afin de mieux comprendre la physique des jets de plasma, nous avons fait interagir deux jets placés l un en face de l autre. L'étude de la contre propagation de deux jets révèle qu il existe une distance minimale d'approche laissant entre eux une zone exempte de plasma. Après l extinction des deux plasmas, une seconde décharge s amorce exactement dans cette zone. Une étude détaillée couplant diagnostics électrique, imagerie ultra-rapide et spectroscopie d'émission nous a permis de montrer que cette décharge secondaire est due à une inversion de polarité conduisant à la création transitoire d'un piège à électrons.Dans le but d'aborder l'étude des applications des jets de plasma au domaine biologique, nous avons également étudié la dégradation de l ADN plasmidique par un jet de plasma. Nous avons mis en évidence que ce type de plasma induit majoritairement des cassures simples et doubles brins, alors que très peu d oxydations de base ou de sites abasiques sont observés, ceci même avec l ajout de quelques pourcents d oxygène dans le gaz.Micro plasma jets operating at atmospheric pressure in free atmosphere have recently attracted great attention because of their numerous advantages. In fact, micro plasma jets can be operated stably at atmospheric pressure and propagated over some centimeters in a free atmosphere. Moreover, these jets are non-thermal plasmas and create numerous reactive species. These properties allow to use this kind of plasma in many applications, such as surface treatment, decontamination, and plasma medicine.In this work it is shown that these micro plasma jets correspond to the fast propagation of an ionization front with no displacement of matter. A characterization of the plasma proprieties (e.g. distance and velocity of propagation) has been done as a function of the applied voltage, gas flow, gas composition and discharge geometry. The spatiotemporal distribution of the reactive species created by the plasma has been measured, with a special focus on the helium metastable atoms which have been measured by absorption laser spectroscopy. The helium metastable atom densities obtained are in the range of 1.10 to 5.10 cm- . Thanks to a very good spatiotemporal resolution, we have done a time-resolved full cartography of the plasma. This allowed us to show that the helium metastable atom distribution is annular near the nozzle and becomes circular as the plasma propagates. The maximum helium metastable atoms density has been measured at about half of the distance where the helium metastable atoms are present. This observation is in contradiction with results reported by numerical models. To gain further insight into the physical processes of the plasma, we have placed two micro plasma jets face to face. This study showed that both plasmas interact in such a way that they never come into contact, letting a space free of plasma between them. Moreover, we revealed that after the extinction of the plasmas, a second discharge is ignited in the previously free space. Fast imaging, spectroscopy diagnostics and electrical measurements showed that this second discharge is due to a polarity reversal, which creates an electron trap. Aiming the study of the application of micro plasma jets in the plasma medicine field, we have studied the degradation of plasmid DNA by our plasma jet. We observed that the plasma treatment leads mostly to single and double strands breaks, and to very little base oxidation and abasite site, even when oxygen is added into the gas mixture.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Les plasmas froids et le Vivant, de nouvelles avancées

Depuis le début des années 2000, des avancées technologiques majeures ont permis l'émergence de plasmas froids à pression atmosphérique ayant de faibles valeurs de courant et des températures proches de la température ambiante. Dans cet article, nous exposons dans un premier temps les principales sources de plasma froid utilisées avec succès dans les applications biomédicales, en insistant notamment sur les propriétés physico-chimiques recherchées. Dans un second temps, nous proposons un état de l'art des dernières avancées médicales (en particulier en cancérologie et en dermatologie), ainsi qu'en agriculture

Spatio-Temporally Resolved Mapping of Helium Metastable Density in an Atmospheric Pressure Plasma Jet

International audienc

Interaction of plasma generated carbon monoxide (CO) with mouse blood hemoglobin

International audienceCarbon monoxide (CO) has a bad reputation due to the potentially lethal consequences when inhaled at high concentrations. However, at low doses CO appears to have many beneficial effects for human health and has a broad spectrum of biological activities such as anti-inflammatory, vasodilatory, anti-apoptotic, and anti-proliferative effects [1],[2]. Plasma can easily generate CO from the dissociation of CO2, as it has been demonstrated in the laser and energy storage fields [3], [4]. In this context, non-equilibrium plasma at atmospheric pressure is an attractive in situ CO source, since it is able to create CO at low doses from CO2 [5]. Moreover, plasma can be used for biomedical applications and intense research is now being conducted on the potential therapeutic use of plasma for the treatment of different pathologies including cancer and skin wounds. Plasmas are very versatile as they possess the capacity to generate large amounts of reactive species combined with electric field, photons and charged particles. Among these are reactive oxygen and nitrogen species (RONS), such nitric oxide (NO), which are produced by the interaction of the plasma with air. NO is widely studied in the field of Plasma Medicine due to its biological role as signaling molecule that functions very similarly to CO [6]–[8]. In fact, CO and NO could be highly complementary due to the different chemical reactivity of these two gases with intracellular cellular targets. However, the combination of plasma and CO for biomedical applications remains to be fully explored. This contribution will focus on the challenge to develop a plasma reactor to generate controlled quantities of CO that can be used for therapeutic purposes. The reactor is based on plasma jet configuration where the discharge is produced in a coaxial dielectric barrier discharge (DBD) reactor equipped with a quartz capillary tube [9]. Helium with small addition of CO2 goes through the device. To assess and quantify the production of CO from plasma, we developed a system whereby mouse blood hemoglobin, a strong scavenger of CO, interacted with the plasma reaction. Once CO binds to hemoglobin, it forms carboxyhemoglobin (COHb), which can be precisely quantified by light absorption. We will present the first results showing that an indirect and a direct plasma treatment have a different influence on the production of CO and its binding to hemoglobin. References[1]R. Motterlini & R. Foresti, Am. J. Physiol. Cell Physiol, vol. 312, n. 3, C302, (2017).[2]R. Motterlini & L. E. Otterbein, Nature Rev. Drug Discov., vol. 9, n. 9, 728, (2010).[3]H. Hokazono & H. Fujimoto, J. Appl. Phys., vol. 62, no. 5, 1585–1594, (1987).[4]A. Lebouvier, S. A. Iwarere, et al., Energy & Fuels, vol. 27, no. 5, 2712–2722, (2013).[5]C. Douat, P. E. Bocamegra, et al., in 24th International Symposium on Plasma Chemistry, 2019.[6]D. B. Graves, IEEE Trans. Radiat. Plasma Med. Sci., vol. 1, no. 4, 281–292, (2017).[7]E. Carbone & C. Douat, Plasma Med., vol. 8, no. 1, 93–120, (2018).[8]V. N. Ayyagari, A. Januszkiewicz, et al., Toxicology, vol. 197, no. 2, 148–163, (2004).[9]T. Darny, J.-M. Pouvesle, et al., Plasma Sources Sci. Technol., vol. 26, no. 4, 045008, (2017)