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Plasma Jet (plasma + jet)
Selected AbstractsAntibacterial Activity of an Atmospheric Pressure Plasma Jet Against Relevant Wound Pathogens in vitro on a Simulated Wound EnvironmentPLASMA PROCESSES AND POLYMERS, Issue 3-4 2010Georg Daeschlein Abstract The aim of the study was to test the efficacy of a hand-held atmospheric pressure plasma jet (APPJ) toward typical wound pathogens in vitro simulating antisepsis on wound surfaces. The plasma jet has been proved to be highly effective in vitro against the most commonly encountered pathogenic species of acute and chronic wounds reaching nearly the power of antiseptics. The following bacteria and fungi were treated on half rigid media (agar) imitating wound colonization: methicillin-sensitive Staphylococcus aureus ATCC 1924 (MSSA), Enterococcus faecium ATCC 6057 (EF), Pseudomonas aeruginosa ATCC 15442 (PA), Candida albicans ATCC 10231 (CA), and , -hemolyzing Streptococci of the Lancefield serogroup A (HSA). Highest reduction factor (RF) was obtained treating PA (RF 4.0) followed by HSA (3.2), MSSA (2.7), CA (2.0), and EF (1.9). Consequently, simulating wound surfaces with moist environment using semisolid agar media, the APPJ allowed bactericidal treatment of highly contaminated surfaces of 55,cm2 imitating skin and wound colonization within 6,min. This antibacterial reduction power together with its handsome flexibility of the APPJ could be a suited therapeutic option in the therapy of infected or colonized wounds. [source] 900-MHz Nonthermal Atmospheric Pressure Plasma Jet for Biomedical ApplicationsPLASMA PROCESSES AND POLYMERS, Issue 3-4 2010Jun Choi Abstract A portable microwave-excited atmospheric pressure plasma jet (APPJ) using a coaxial transmission line resonator is introduced for applications of plasma biomedicine. Its unique feature includes the portability and no need for matching network and cooling system with high power efficiency, operating at 900,MHz with low ignition power less than 2.5,W in argon at atmospheric pressure. The temperature at the downstream of the APPJ stays less than 47,°C (,320,K) during 5,min of continuous operation. The optical emission spectrum of the APPJ shows various reactive radicals such as OH, NO, and O which are responsible for biomedicine. The APPJ was applied to investigate the acceleration of blood coagulation, which occurred within 20,s of plasma treatment in vitro and within 1,min in vivo. This is significantly faster than the natural coagulation. [source] Plasma Polymerization of HMDSO with an Atmospheric Pressure Plasma Jet for Corrosion Protection of Aluminum and Low-Adhesion SurfacesPLASMA PROCESSES AND POLYMERS, Issue 10 2009Uwe Lommatzsch Abstract Thin functional films were deposited on aluminum with an atmospheric pressure plasma jet using hexamethyldisiloxane (HMDSO) as precursor. A high dynamic deposition rate on the order of 450,nm,·,m,·,min,1 was achieved. Composition and structure of the thin films show a strong dependence on the downstream location of the precursor injection. A 4,mm downstream shift of the precursor injection increases the carbon content in the thin film by a factor of 2.5, as indicated by XPS analysis and alters the degree of cross-linking according to the FTIR spectra. The coating with the low carbon content (17 at.-%) provides corrosion resistance for aluminum 2024 unclad exposed for 96,h to a neutral salt spray test. The coating with the high carbon content reduces the adhesion of an epoxy resin to the surface and may be used as a release coating. [source] A Simple Optical Monitoring Technique for Determining the Geometrical Characteristics of a Plasma JetPLASMA PROCESSES AND POLYMERS, Issue 2 2006Boyan E. Djakov Abstract Summary: A sensor device is proposed to evaluate the location, size, and shape of a plasma jet. It consists of a small number (e.g., six) of photodetectors arranged in a cross-sectional plane of the jet. Tests of the technique are made by simulations based on CCD images of a plasma jet taken simultaneously from three different angles of view. Photodiode configuration [source] Improved Plasma Spray Torch Stability Through Multi-Electrode DesignCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7 2007J. Schein Abstract Coating production by thermal plasma spray is dependent on the residence time of particles in the plasma jet produced by the gas flow inside a plasma torch. To ensure a high fraction of well-molten particles to be accelerated towards the substrate a long reproducible residence time is needed. This can be achieved by a long plasma jet with little or no temporal variation in length and temperature. While single electrode plasma torches need an unstable attachment of the anodic arc root in order to avoid excess erosion, which also causes an unstable plasma jet, multi-electrode torches allow operation with fixed anode attachments by subdividing the anode current by the number of electrodes used, and thereby thus reducing the power input for each separated arc root. Once the steady anode attachment has been obtained the produced plasma jet exhibits a steady characteristic, but also looses rotational symmetry. The separation can be achieved by using either multi anode or multi cathode geometry with appropriate electrical control. Both version have been produced with 3 electrodes each resulting in two systems known as the Delta Gun (3 anodes) and Triplex (3 cathodes). (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Modeling of Coating Process, Phase Changes, and Damage of Plasma Sprayed Thermal Barrier Coatings on Ni-Base Superalloys,ADVANCED ENGINEERING MATERIALS, Issue 3 2010Tilmann Beck The paper gives an overview on the modeling activities on plasma sprayed thermal barrier coating in the frame of TFB 63. In the first part, through-process modeling of the APS deposition of a ZrO2 based TBC is described. Starting from simulation of the plasma jet, heat transfer into the powder particles, particle melting, particle impact on the substrate surface, and solidification is simulated. A homogenization method is introduced to describe the mechanical properties of the resulting TBC. The second part shows simulation of interdiffusion and phase transformations of MCrAlY and intermetallic oxidation protection coatings on several cast Ni-base alloy substrates. Finally, FEM-based damage simulation of oxidation protection coatings by transversal fatigue cracks during thermomechanical fatigue loading as well as by delamination of the TBC during thermocyclic loading is discussed. [source] Flow characteristics of a cold helium arc-jet plasma along open field linesIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 3 2009Kazuyuki Yoshida Member Abstract We experimentally study plasma parameters including ion acoustic Mach number of expanding cold helium plasma jet with an electron temperature of less than 1 eV flowing along open field lines. It is experimentally found that the ion Mach number increases from 1 to 3, and that the plasma potential decreases by about 1 V. We discuss the experimental results based on a quasi one-dimensional flow model in which the plasma is assumed to be quasi-neutral and in a state of thermodynamic equilibrium. Our model describes the ion acceleration, the axial profiles of the potential drop, and the electron temperature/density. The model also shows that the helium ions are accelerated both by the electric field and by the increasing cross-sectional area of the transonic flow. After the ion acceleration, the ion Mach number decreases and the electron temperature increases. These phenomena are discussed in terms of a shock wave. It is noted that the electron density decreases even in the shock wave. This is discussed in terms of rapid recombination because of the low electron temperature. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Antibacterial Activity of an Atmospheric Pressure Plasma Jet Against Relevant Wound Pathogens in vitro on a Simulated Wound EnvironmentPLASMA PROCESSES AND POLYMERS, Issue 3-4 2010Georg Daeschlein Abstract The aim of the study was to test the efficacy of a hand-held atmospheric pressure plasma jet (APPJ) toward typical wound pathogens in vitro simulating antisepsis on wound surfaces. The plasma jet has been proved to be highly effective in vitro against the most commonly encountered pathogenic species of acute and chronic wounds reaching nearly the power of antiseptics. The following bacteria and fungi were treated on half rigid media (agar) imitating wound colonization: methicillin-sensitive Staphylococcus aureus ATCC 1924 (MSSA), Enterococcus faecium ATCC 6057 (EF), Pseudomonas aeruginosa ATCC 15442 (PA), Candida albicans ATCC 10231 (CA), and , -hemolyzing Streptococci of the Lancefield serogroup A (HSA). Highest reduction factor (RF) was obtained treating PA (RF 4.0) followed by HSA (3.2), MSSA (2.7), CA (2.0), and EF (1.9). Consequently, simulating wound surfaces with moist environment using semisolid agar media, the APPJ allowed bactericidal treatment of highly contaminated surfaces of 55,cm2 imitating skin and wound colonization within 6,min. This antibacterial reduction power together with its handsome flexibility of the APPJ could be a suited therapeutic option in the therapy of infected or colonized wounds. [source] 900-MHz Nonthermal Atmospheric Pressure Plasma Jet for Biomedical ApplicationsPLASMA PROCESSES AND POLYMERS, Issue 3-4 2010Jun Choi Abstract A portable microwave-excited atmospheric pressure plasma jet (APPJ) using a coaxial transmission line resonator is introduced for applications of plasma biomedicine. Its unique feature includes the portability and no need for matching network and cooling system with high power efficiency, operating at 900,MHz with low ignition power less than 2.5,W in argon at atmospheric pressure. The temperature at the downstream of the APPJ stays less than 47,°C (,320,K) during 5,min of continuous operation. The optical emission spectrum of the APPJ shows various reactive radicals such as OH, NO, and O which are responsible for biomedicine. The APPJ was applied to investigate the acceleration of blood coagulation, which occurred within 20,s of plasma treatment in vitro and within 1,min in vivo. This is significantly faster than the natural coagulation. [source] Influence of Cold Plasma Atmospheric Jet on Surface Integrin Expression of Living CellsPLASMA PROCESSES AND POLYMERS, Issue 3-4 2010Alexey Shashurin Abstract The effects induced in cells due to treatment with cold atmospheric plasma jet are studied. Cell migration rate is measured by means of time-lapse microscopy. In order to characterize cell surface integrin expression, the fluorescent response of cells after surface integrins are stained with specific antibodies is measured by flow cytometry. We show that treatment of cells with plasma jet affects the cells on sub-cellular level, namely decreases expression of cell surface integrins (,1 and ,v integrins were tested). This change in integrin expression might be the original cause for the effects observed on cellular level, such as reduced cell migration rate and cell detachment observed experimentally. [source] Plasma Polymerization of HMDSO with an Atmospheric Pressure Plasma Jet for Corrosion Protection of Aluminum and Low-Adhesion SurfacesPLASMA PROCESSES AND POLYMERS, Issue 10 2009Uwe Lommatzsch Abstract Thin functional films were deposited on aluminum with an atmospheric pressure plasma jet using hexamethyldisiloxane (HMDSO) as precursor. A high dynamic deposition rate on the order of 450,nm,·,m,·,min,1 was achieved. Composition and structure of the thin films show a strong dependence on the downstream location of the precursor injection. A 4,mm downstream shift of the precursor injection increases the carbon content in the thin film by a factor of 2.5, as indicated by XPS analysis and alters the degree of cross-linking according to the FTIR spectra. The coating with the low carbon content (17 at.-%) provides corrosion resistance for aluminum 2024 unclad exposed for 96,h to a neutral salt spray test. The coating with the high carbon content reduces the adhesion of an epoxy resin to the surface and may be used as a release coating. [source] Cover Picture: Plasma Process.PLASMA PROCESSES AND POLYMERS, Issue 8 2006Polym. Cover: The picture shows different discharges in an atmospheric pressure plasma jet (APPJ), operated at 13.56 MHz in a gap of 2 mm. The discharges shown are from top to bottom: ,-mode in helium, ,-mode in helium, ,-mode in argon and coexisting ,- and ,-mode in argon. Further details can be found in the article by J. Laimer* and H. Störi on page 573. [source] A Simple Optical Monitoring Technique for Determining the Geometrical Characteristics of a Plasma JetPLASMA PROCESSES AND POLYMERS, Issue 2 2006Boyan E. Djakov Abstract Summary: A sensor device is proposed to evaluate the location, size, and shape of a plasma jet. It consists of a small number (e.g., six) of photodetectors arranged in a cross-sectional plane of the jet. Tests of the technique are made by simulations based on CCD images of a plasma jet taken simultaneously from three different angles of view. Photodiode configuration [source] Theoretical Analysis of Plasma Enhancement of Propellant Burning RatePROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2007Roger Alimi Abstract A theoretical model of the combustion of a nitramine solid propellant in the presence of a plasma jet is proposed. Unlike standard double-base compositions, nitramine propellants exhibit experimental evidence that plasma induces a burning rate enhancement. The model is based on heat transfer considerations and proposes a closed-form solution of the enhancement of the propellant burning rate as a function of the thermophysical parameters of the system. The model provides a good qualitative agreement with experimental results. [source] | ||||||||||