Removal of Pollutants by Atmospheric Non Thermal Plasmas

Results on the application of non thermal plasmas in two environmentally important fields: oxidative removal of VOC and NOx in excess of oxygen were presented. The synergetic application of a plasma-catalytic treatment of NOx in excess of oxygen is also described.Comment: 6 pages; Published in Catalysis for Environment: Depollution, Renewable Energy and Clean Fuels, Zakopane : Pologne (2008

Dynamics of ionization wave splitting and merging of atmospheric-pressure plasmas in branched dielectric tubes and channels

Atmospheric-pressure fast ionization waves (FIWs) generated by nanosecond, high voltage pulses are able to propagate long distances through small diameter dielectric tubes or channels, and so deliver UV fluxes, electric fields, charged and excited species to remote locations. In this paper, the dynamics of FIW splitting and merging in a branched dielectric channel are numerically investigated using a two-dimensional plasma hydrodynamics model with radiation transport, and the results are compared with experiments. The channel consists of a straight inlet section branching 90° into a circular loop which terminates to form a second straight outlet section aligned with the inlet section. The plasma is sustained in neon gas with a trace amount of xenon at atmospheric pressure. The FIW generated at the inlet approaches the first branch point with speeds of ≈10 8 cm s −1 , and produces a streamer at the inlet–loop junction. The induced streamer then splits into two FIW fronts, each propagating in opposite directions through half of the loop channel. The FIWs slow as they traverse the circular sections due to a shorting of the electric field by the other FIW. Approaching the loop–outlet junction, the two FIW fronts nearly come to a halt, induce another streamer which goes through further splitting and finally develops into a new FIW front. The new FIW increases in speed and plasma density propagating in the straight outlet channel. The electrical structure of the FIWs and the induced streamers during the splitting and merging processes are discussed with an emphasis on their mutual influence and their interaction with the channel wall. The FIW propagation pattern is in good agreement with experimental observations. Based on numerical and experimental investigations, a model for the splitting and merging FIWs in the branched loop channel is proposed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98591/1/0022-3727_45_27_275201.pd

Distribution and penetration of reactive oxygen and nitrogen species through a tissue phantom after Plasma Gun treatment

International audienceThe transport and distribution phenomena of reactive oxygen and nitrogen species (RONS) into biological tissue following non-thermal plasma treatment have received much attention. The aim of this study is to test the efficacy of Plasma Gun (PG) on transporting the reactive species in an agar composed tissue phantom. RONS are generated on the agar gel by the plasma treatment and they continue to spread in the depth after plasma exposure. The amount of RONS after passing through the tissue phantom are strongly depending on discharge parameters such as distance to the target and capillary shape

Fluorescein-agarose gel as a tissue model to visualize and measure local CAP-induced acidification

International audienceCold Atmospheric Plasmas (CAPs) have been shown to lower the pH of the treated target. CAP-induced acidification can have beneficial effects on the treated tissue (e.g. disinfection and healing). Conversely a tissue hyper acidification can lead to permanent damages with dramatic consequences. Before starting in vivo plasma treatments, preliminary tests should be carried in order to tune the acidifying effect induced by CAP exposition. Here we propose a tissue model that can be a useful tool to visualize and measure pH changes induced by plasma treatment

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

Plasma and Aerosols: Challenges, Opportunities and Perspectives

The interaction of plasmas and liquid aerosols offers special advantages and opens new perspectives for plasma\u2013liquid applications. The paper focuses on the key research challenges and potential of plasma-aerosol interaction at atmospheric pressure in several fields, outlining opportunities and benefits in terms of process tuning and throughputs. After a short overview of the recent achievements in plasma\u2013liquid field, the possible application benefits from aerosol injection in combination with plasma discharge are listed and discussed. Since the nature of the chemicophysical plasma-droplet interactions is still unclear, a multidisciplinary approach is recommended to overcome the current lack of knowledge and to open the plasma communities to scientists from other fields, already active in biphasic systems diagnostic. In this perspective, a better understanding of the high chemical reactivity of gas\u2013liquid reactions will bring new opportunities for plasma assisted in-situ and on-demand reactive species production and material processing

Contrôle d'un écoulement subsonique par utilisation de décharges surfaciques

Dans cet article, des décharges électriques ont été étudiées dans l'air ambiant, afin d'agir sur des écoulements subsoniques. Les écoulements induits par une décharge couronne continue et une Décharge à Barrière Diélectrique (DBD) alternative ont été mesurés avec le système PIV. On montre ainsi la topologie de l'écoulement pour ces deux configurations, avec une vitesse maximale de 3,75 m/s. Ces décharges ont été utilisées sur des profils d'ailes dans des souffleries subsoniques. Des écoulements totalement décollés ont été ré-attachés par la décharge couronne pour des nombres des Reynolds allant jusqu'à 267 000 et 15°. Un actionneur constitué d'une succession de DBD a permis de retarder la séparation de l'écoulement de 8% pour un nombre de Reynolds de 800 000

Grand Challenges in Low Temperature Plasmas

Low temperature plasmas (LTPs) enable to create a highly reactive environment at near ambient temperatures due to the energetic electrons with typical kinetic energies in the range of 1 to 10 eV (1 eV = 11600K), which are being used in applications ranging from plasma etching of electronic chips and additive manufacturing to plasma-assisted combustion. LTPs are at the core of many advanced technologies. Without LTPs, many of the conveniences of modern society would simply not exist. New applications of LTPs are continuously being proposed. Researchers are facing many grand challenges before these new applications can be translated to practice. In this paper, we will discuss the challenges being faced in the field of LTPs, in particular for atmospheric pressure plasmas, with a focus on health, energy and sustainability