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Sample records for dalam plasma jet

  1. Plasma confinement at JET

    NASA Astrophysics Data System (ADS)

    Nunes, I.; JET Contributors

    2016-01-01

    Operation with a Be/W wall at JET (JET-ILW) has an impact on scenario development and energy confinement with respect to the carbon wall (JET-C). The main differences observed were (1) strong accumulation of W in the plasma core and (2) the need to mitigate the divertor target temperature to avoid W sputtering by Be and other low Z impurities and (3) a decrease of plasma energy confinement. A major difference is observed on the pedestal pressure, namely a reduction of the pedestal temperature which, due to profile stiffness the plasma core temperature is also reduced leading to a degradation of the global confinement. This effect is more pronounced in low β N scenarios. At high β N, the impact of the wall on the plasma energy confinement is mitigated by the weaker plasma energy degradation with power relative to the IPB98(y, 2) scaling calculated empirically for a CFC first wall. The smaller tolerable impurity concentration for tungsten (<10-5) compared to that of carbon requires the use of electron heating methods to prevent W accumulation in the plasma core region as well as gas puffing to avoid W entering the plasma core by ELM flushing and reduction of the W source by decreasing the target temperature. W source and the target temperature can also be controlled by impurity seeding. Nitrogen and Neon have been used and with both gases the reduction of the W source and the target temperature is observed. Whilst more experiments with Neon are necessary to assess its impact on energy confinement, a partial increase of plasma energy confinement is observed with Nitrogen, through the increase of edge temperature. The challenge for scenario development at JET is to extend the pulse length curtailed by its transient behavior (W accumulation or MHD), but more importantly by the divertor target temperature limits. Re-optimisation of the scenarios to mitigate the effect of the change of wall materials maintaining high global energy confinement similar to JET-C is

  2. Dense Hypervelocity Plasma Jets

    NASA Astrophysics Data System (ADS)

    Case, Andrew; Witherspoon, F. Douglas; Messer, Sarah; Bomgardner, Richard; Phillips, Michael; van Doren, David; Elton, Raymond; Uzun-Kaymak, Ilker

    2007-11-01

    We are developing high velocity dense plasma jets for fusion and HEDP applications. Traditional coaxial plasma accelerators suffer from the blow-by instability which limits the mass accelerated to high velocity. In the current design blow-by is delayed by a combination of electrode shaping and use of a tailored plasma armature created by injection of a high density plasma at a few eV generated by arrays of capillary discharges or sparkgaps. Experimental data will be presented for a complete 32 injector gun system built for driving rotation in the Maryland MCX experiment, including data on penetration of the plasma jet through a magnetic field. We present spectroscopic measurements of plasma velocity, temperature, and density, as well as total momentum measured using a ballistic pendulum. Measurements are in agreement with each other and with time of flight data from photodiodes and a multichannel PMT. Plasma density is above 10^15 cm-3, velocities range up to about 100 km/s. Preliminary results from a quadrature heterodyne HeNe interferometer are consistent with these results.

  3. Dense Hypervelocity Plasma Jets

    NASA Astrophysics Data System (ADS)

    Witherspoon, F. Douglas; Case, Andrew; Phillips, Michael W.

    2006-10-01

    High velocity dense plasma jets are under continued experimental development for a variety of fusion applications including refueling, disruption mitigation, rotation drive, and magnetized target fusion. The technical goal is to accelerate plasma slugs of density >10^17 cm-3 and total mass >100 micrograms to velocities >200 km/s. The approach utilizes symmetrical injection of very high density plasma into a coaxial EM accelerator having a tailored cross-section geometry to prevent formation of the blow-by instability. Injected plasma is generated by electrothermal capillary discharges using either cylindrical capillaries or a newer toroidal spark gap arrangement that has worked at pressures as low as 3.5 x10-6 Torr in bench tests. Experimental plasma data will be presented for a complete 32 injector accelerator system recently built for driving rotation in the Maryland MCX experiment which utilizes the cylindrical capillaries, and also for a 50 spark gap test unit currently under construction.

  4. Plasma jet takes off.

    PubMed Central

    Frazer, L

    1999-01-01

    Thanks to a series of joint research projects by Los Alamos National Laboratory, Beta Squared of Allen, Texas, and the University of California at Los Angeles, there is now a more environmentally sound method for cleaning semiconductor chips that may also be effective in cleaning up chemical, bacterial, and nuclear contaminants. The Atmospheric Pressure Plasma Jet uses a type of ionized gas called plasma to clean up contaminants by binding to them and lifting them away. In contrast to the corrosive acids and chemical solvents traditionally used to clean semiconductor chips, the jet oxidizes contaminants, producing only benign gaseous by-products such as oxygen and carbon dioxide. The new technology is also easy to transport, cleans thoroughly and quickly, and presents no hazards to its operators. PMID:10417375

  5. Plasma jet ignition device

    DOEpatents

    McIlwain, Michael E.; Grant, Jonathan F.; Golenko, Zsolt; Wittstein, Alan D.

    1985-01-15

    An ignition device of the plasma jet type is disclosed. The device has a cylindrical cavity formed in insulating material with an electrode at one end. The other end of the cylindrical cavity is closed by a metal plate with a small orifice in the center which plate serves as a second electrode. An arc jumping between the first electrode and the orifice plate causes the formation of a highly-ionized plasma in the cavity which is ejected through the orifice into the engine cylinder area to ignite the main fuel mixture. Two improvements are disclosed to enhance the operation of the device and the length of the plasma plume. One improvement is a metal hydride ring which is inserted in the cavity next to the first electrode. During operation, the high temperature in the cavity and the highly excited nature of the plasma breaks down the metal hydride, liberating hydrogen which acts as an additional fuel to help plasma formation. A second improvement consists of a cavity insert containing a plurality of spaced, metal rings. The rings act as secondary spark gap electrodes reducing the voltage needed to maintain the initial arc in the cavity.

  6. Atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S.

    1999-01-01

    Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

  7. EDITORIAL: Plasma jets and plasma bullets Plasma jets and plasma bullets

    NASA Astrophysics Data System (ADS)

    Kong, M. G.; Ganguly, B. N.; Hicks, R. F.

    2012-06-01

    Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma plume gives rise to a strong interaction with its surrounding environment, and the interaction alters the properties of both the plasma and the environment, often in a nonlinear and dynamic fashion. The plasma is therefore not confined by defined physical walls, thus extending opportunities for material treatment applications as well as bringing in new challenges in science and technology associated with complex open-boundary problems. Some of the most common examples may be found in dense plasmas with very high dissipation of externally supplied energy (e.g. in electrical, optical or thermal forms) and often in or close to thermal equilibrium. For these dense plasmas, their characteristics are determined predominantly by strong physical forces of different fields, such as electrical, magnetic, thermal, shock wave, and their nonlinear interactions [1]. Common to these dense plasma plumes are significant macroscopic plasma movement and considerable decomposition of solid materials (e.g. vaporization). Their applications are numerous and include detection of elemental traces, synthesis of high-temperature materials and welding, laser--plasma interactions, and relativistic jets in particle accelerators and in space [2]-[4]. Scientific challenges in the understanding of plasma jets are exciting and multidisciplinary, involving interweaving transitions of all four states of matter, and their technological applications are wide-ranging and growing rapidly. Using the Web of Science database, a search for journal papers on non-fusion plasma jets reveals that a long initial phase up

  8. EDITORIAL: Plasma jets and plasma bullets Plasma jets and plasma bullets

    NASA Astrophysics Data System (ADS)

    Kong, M. G.; Ganguly, B. N.; Hicks, R. F.

    2012-06-01

    Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma plume gives rise to a strong interaction with its surrounding environment, and the interaction alters the properties of both the plasma and the environment, often in a nonlinear and dynamic fashion. The plasma is therefore not confined by defined physical walls, thus extending opportunities for material treatment applications as well as bringing in new challenges in science and technology associated with complex open-boundary problems. Some of the most common examples may be found in dense plasmas with very high dissipation of externally supplied energy (e.g. in electrical, optical or thermal forms) and often in or close to thermal equilibrium. For these dense plasmas, their characteristics are determined predominantly by strong physical forces of different fields, such as electrical, magnetic, thermal, shock wave, and their nonlinear interactions [1]. Common to these dense plasma plumes are significant macroscopic plasma movement and considerable decomposition of solid materials (e.g. vaporization). Their applications are numerous and include detection of elemental traces, synthesis of high-temperature materials and welding, laser--plasma interactions, and relativistic jets in particle accelerators and in space [2]-[4]. Scientific challenges in the understanding of plasma jets are exciting and multidisciplinary, involving interweaving transitions of all four states of matter, and their technological applications are wide-ranging and growing rapidly. Using the Web of Science database, a search for journal papers on non-fusion plasma jets reveals that a long initial phase up

  9. Modelling the Plasma Jet in Multi-Arc Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Öte, M.; Schein, J.; Zimmermann, S.; Möhwald, K.; Lummer, C.

    2016-08-01

    Particle in-flight characteristics in atmospheric plasma spraying process are determined by impulse and heat energy transferred between the plasma jet and injected powder particles. One of the important factors for the quality of the plasma-sprayed coatings is thus the distribution of plasma gas temperatures and velocities in plasma jet. Plasma jets generated by conventional single-arc plasma spraying systems and their interaction with powder particles were subject matter of intensive research. However, this does not apply to plasma jets generated by means of multi-arc plasma spraying systems yet. In this study, a numerical model has been developed which is designated to dealing with the flow characteristics of the plasma jet generated by means of a three-cathode spraying system. The upstream flow conditions, which were calculated using a priori conducted plasma generator simulations, have been coupled to the plasma jet simulations. The significances of the relevant numerical assumptions and aspects of the models are analyzed. The focus is placed on to the turbulence and diffusion/demixing modelling. A critical evaluation of the prediction power of the models is conducted by comparing the numerical results to the experimental results determined by means of emission spectroscopic computed tomography. It is evident that the numerical models exhibit a good accuracy for their intended use.

  10. Plasma jet electrode has longer operating life

    NASA Technical Reports Server (NTRS)

    Gracey, C. M.

    1967-01-01

    Water-cooled, silver-infiltrated tungsten electrode has twice the operating lifetime of the pure tungsten electrode used in plasma jet generators. This electrode reduces the erosion rate, ensures excellent heat transfer, and reduces thermal stresses.

  11. Merging of high speed argon plasma jets

    SciTech Connect

    Case, A.; Messer, S.; Brockington, S.; Wu, L.; Witherspoon, F. D.; Elton, R.

    2013-01-15

    Formation of an imploding plasma liner for the plasma liner experiment (PLX) requires individual plasma jets to merge into a quasi-spherical shell of plasma converging on the origin. Understanding dynamics of the merging process requires knowledge of the plasma phenomena involved. We present results from the study of the merging of three plasma jets in three dimensional geometry. The experiments were performed using HyperV Technologies Corp. 1 cm Minirailguns with a preionized argon plasma armature. The vacuum chamber partially reproduces the port geometry of the PLX chamber. Diagnostics include fast imaging, spectroscopy, interferometry, fast pressure probes, B-dot probes, and high speed spatially resolved photodiodes, permitting measurements of plasma density, temperature, velocity, stagnation pressure, magnetic field, and density gradients. These experimental results are compared with simulation results from the LSP 3D hybrid PIC code.

  12. Arc plasma jets of a nontransferred plasma torch

    SciTech Connect

    Kang, K.D.; Hong, S.H.

    1996-02-01

    The dc plasma torches have been widely used as clean plasma sources for plasma processings such as plasma spraying and synthesis. The plasma flow of a nontransferred plasma torch used for thermal plasma processings is produced by the arc-gas interactions between a cathode tip and an anode nozzle and expands as a jet through the nozzle. In this work, numerically calculated images of the arc plasma characteristics are found over the entire plasma region, including both an arc-gas interacting region inside the torch and a jet expanding region outside the torch. A numerical model used assumes a local thermodynamic equilibrium (LTE) with near-electrode phenomena and compressible flow effects. The computational system is described by a two-dimensional (2-D) axisymmetric model which is solved for plasma temperature and velocity by a control volume approach with the modified SIMPLER algorithm in a real torch geometry.

  13. Structure and Dynamics of Colliding Plasma Jets

    DOE PAGESBeta

    Li, C.; Ryutov, D.; Hu, S.; Rosenberg, M.; Zylstra, A.; Seguin, F.; Frenje, J.; Casey, D.; Gatu Johnson, M.; Manuel, M.; et al

    2013-12-01

    Monoenergetic-proton radiographs of laser-generated, high-Mach-number plasma jets colliding at various angles shed light on the structures and dynamics of these collisions. The observations compare favorably with results from 2D hydrodynamic simulations of multistream plasma jets, and also with results from an analytic treatment of electron flow and magnetic field advection. In collisions of two noncollinear jets, the observed flow structure is similar to the analytic model’s prediction of a characteristic feature with a narrow structure pointing in one direction and a much thicker one pointing in the opposite direction. Spontaneous magnetic fields, largely azimuthal around the colliding jets and generatedmore » by the well-known ∇Te ×∇ne Biermann battery effect near the periphery of the laser spots, are demonstrated to be “frozen in” the plasma (due to high magnetic Reynolds number RM ~5×10⁴) and advected along the jet streamlines of the electron flow. These studies provide novel insight into the interactions and dynamics of colliding plasma jets.« less

  14. Structure and Dynamics of Colliding Plasma Jets

    SciTech Connect

    Li, C.; Ryutov, D.; Hu, S.; Rosenberg, M.; Zylstra, A.; Seguin, F.; Frenje, J.; Casey, D.; Gatu Johnson, M.; Manuel, M.; Rinderknecht, H.; Petrasso, R.; Amendt, P.; Park, H.; Remington, B.; Wilks, S.; Betti, R.; Froula, D.; Knauer, J.; Meyerhofer, D.; Drake, R.; Kuranz, C.; Young, R.; Koenig, M.

    2013-12-01

    Monoenergetic-proton radiographs of laser-generated, high-Mach-number plasma jets colliding at various angles shed light on the structures and dynamics of these collisions. The observations compare favorably with results from 2D hydrodynamic simulations of multistream plasma jets, and also with results from an analytic treatment of electron flow and magnetic field advection. In collisions of two noncollinear jets, the observed flow structure is similar to the analytic model’s prediction of a characteristic feature with a narrow structure pointing in one direction and a much thicker one pointing in the opposite direction. Spontaneous magnetic fields, largely azimuthal around the colliding jets and generated by the well-known ∇Te ×∇ne Biermann battery effect near the periphery of the laser spots, are demonstrated to be “frozen in” the plasma (due to high magnetic Reynolds number RM ~5×10⁴) and advected along the jet streamlines of the electron flow. These studies provide novel insight into the interactions and dynamics of colliding plasma jets.

  15. Portable nanosecond pulsed air plasma jet

    SciTech Connect

    Walsh, J. L.; Kong, M. G.

    2011-08-22

    Low-temperature atmospheric pressure plasmas are of great importance in many emerging biomedical and materials processing applications. The redundancy of a vacuum system opens the gateway for highly portable plasma systems, for which air ideally becomes the plasma-forming gas and remote plasma processing is preferred to ensure electrical safety. Typically, the gas temperature observed in air plasma greatly exceeds that suitable for the processing of thermally liable materials; a large plasma-sample distance offers a potential solution but suffers from a diluted downstream plasma chemistry. This Letter reports a highly portable air plasma jet system which delivers enhanced downstream chemistry without compromising the low temperature nature of the discharge, thus forming the basis of a powerful tool for emerging mobile plasma applications.

  16. Numerical Simulations of Plasma Jets for PLX

    NASA Astrophysics Data System (ADS)

    Wu, L.; Messer, S.; Case, A.; Phillips, M.; Witherspoon, F. D.; Welch, D.; Thoma, C.; Bogatu, I. N.; Galkin, S.; Thompson, J. R.; Kim, J. S.; Macfarlane, J.; Golovkin, I.

    2011-10-01

    Two and three-dimensional simulations are performed using the hybrid particle-in-cell code LSP to study liner formation for the Plasma Liner Experiment (PLX). These include studies of plasma transport within small parallel-plate MiniRailguns, issues related to detachment of the jet from the nozzle, and the subsequent propagation of single jets in Cartesian coordinates. Merging of plasma jets is studied mainly in cylindrical coordinates at present. Varied number of railguns (or jets) are used in this study with initial velocity of 50-100 km/s, initial argon number density of 1016 cm-3 to 1017 cm-3, and initial temperature of ~3 eV. The effects on liner formation from jet initial profiles (density, velocity and temperature distribution) are studied to explore behavior. Simulation results are presented and compared with experimental data from merging jet experiments currently being conducted at HyperV using 1cm bore MiniRailguns. The LSP code is used to perform the simulations using improved fluid algorithms and equation-of-state models from Voss and atomic data from Prism. Work supported by the U.S. DOE Office of Fusion Energy Sciences. Work supported by the U.S. DOE Office of Fusion Energy Sciences.

  17. Measurement of air entrainment in plasma jets

    SciTech Connect

    Fincke, J.R.; Rodriquez, R.; Pentecost, C.G.

    1990-01-01

    The concentration and temperature of air entrained into argon and helium plasma jets has been measured using coherent anti-Stokes Raman spectroscopy (CARS). The argon plasma flow field is characterized by a short region of well behaved laminar flow near the nozzle exit followed by an abrupt transition to turbulence. Once the transition of turbulence occurs, air is rapidly mixed into the jet core. The location of the transition region is determined by the rapid cooling of the jet and the resulting increase in Reynolds number. In contrast, the helium plasma flow field never exceeds a Reynolds number of 200 and remains laminar. The entrainment process in this case is controlled by molecular diffusion rather than turbulent mixing. 9 refs., 5 figs., 1 tab.

  18. Measurement of air entrainment in plasma jets

    NASA Astrophysics Data System (ADS)

    Fincke, J. R.; Rodriquez, R.; Pentecost, C. G.

    The concentration and temperature of air entrained into argon and helium plasma jets has been measured using coherent anti-Stokes Raman spectroscopy (CARS). The argon plasma flow field is characterized by a short region of well behaved laminar flow near the nozzle exit followed by an abrupt transition to turbulence. Once the transition of turbulence occurs, air is rapidly mixed into the jet core. The location of the transition region is determined by the rapid cooling of the jet and the resulting increase in Reynolds number. In contrast, the helium plasma flow field never exceeds a Reynolds number of 200 and remains laminar. The entrainment process in this case is controlled by molecular diffusion rather than turbulent mixing.

  19. Inductive Measurement of Plasma Jet Electrical Conductivity

    NASA Technical Reports Server (NTRS)

    Turner, Matthew W.; Hawk, Clark W.; Litchford, Ron J.

    2005-01-01

    An inductive probing scheme, originally developed for shock tube studies, has been adapted to measure explosive plasma jet conductivities. In this method, the perturbation of an applied magnetic field by a plasma jet induces a voltage in a search coil, which, in turn, can be used to infer electrical conductivity through the inversion of a Fredholm integral equation of the first kind. A 1-inch diameter probe was designed and constructed, and calibration was accomplished by firing an aluminum slug through the probe using a light-gas gun. Exploratory laboratory experiments were carried out using plasma jets expelled from 15-gram high explosive shaped charges. Measured conductivities were in the range of 3 kS/m for unseeded octol charges and 20 kS/m for seeded octol charges containing 2% potassium carbonate by mass.

  20. Dense Plasma Injectors for the HyperV Plasma Jets

    NASA Astrophysics Data System (ADS)

    Witherspoon, F. Douglas; Bomgardner, Richard; Case, Andrew; Messer, Sarah; Brockington, Samuel

    2008-04-01

    HyperV is developing high velocity dense plasma jets for application to fusion and HEDP. The approach uses symmetric pulsed injection of high density plasma into a coaxial EM accelerator having a cross-section tailored to prevent formation of the blow-by instability. Work to date has focused on injection using ablative plasma sources, such as capillaries and sparkgaps, but injection of pure plasma, such as D and T, or high-Z gases such as Argon, require a different approach. We describe experiments and diagnostic measurements to develop small parallel plate railguns (MiniRailguns) to generate high density plasma pulses for injection into the coax gun. We also present a brief update of latest results from the 112 electrode sparkgap gun and the 64 capillary TwoPi plasma jet merging experiment, both of which have been upgraded with higher energy pulse forming networks to double the mass of ablatively injected plasma.

  1. Laboratory plasma physics experiments using merging supersonic plasma jets

    SciTech Connect

    Hsu, S. C.; Moser, A. L.; Merritt, E. C.; Adams, C. S.; Dunn, J. P.; Brockington, S.; Case, A.; Gilmore, M.; Lynn, A. G.; Messer, S. J.; Witherspoon, F. D.

    2015-04-01

    We describe a laboratory plasma physics experiment at Los Alamos National Laboratory that uses two merging supersonic plasma jets formed and launched by pulsed-power-driven railguns. The jets can be formed using any atomic species or mixture available in a compressed-gas bottle and have the following nominal initial parameters at the railgun nozzle exit: ne ≈ ni ~ 10¹⁶ cm⁻³, Te ≈ Ti ≈ 1.4 eV, Vjet ≈ 30–100 km/s, mean charge $\\bar{Z}$ ≈ 1, sonic Mach number Ms ≡ Vjet/Cs > 10, jet diameter = 5 cm, and jet length ≈ 20 cm. Experiments to date have focused on the study of merging-jet dynamics and the shocks that form as a result of the interaction, in both collisional and collisionless regimes with respect to the inter-jet classical ion mean free path, and with and without an applied magnetic field. However, many other studies are also possible, as discussed in this paper.

  2. Laboratory plasma physics experiments using merging supersonic plasma jets

    NASA Astrophysics Data System (ADS)

    Hsu, S. C.; Moser, A. L.; Merritt, E. C.; Adams, C. S.; Dunn, J. P.; Brockington, S.; Case, A.; Gilmore, M.; Lynn, A. G.; Messer, S. J.; Witherspoon, F. D.

    2015-04-01

    We describe a laboratory plasma physics experiment at Los Alamos National Laboratory that uses two merging supersonic plasma jets formed and launched by pulsed-power-driven railguns. The jets can be formed using any atomic species or mixture available in a compressed-gas bottle and have the following nominal initial parameters at the railgun nozzle exit: ne ~ ni ~ 1016 cm-3, Te ~ Ti ~ 1.4 eV, V jet ~ 30-100 km/s, mean charge $\\bar{Z}$ ~ 1, sonic Mach number Ms ≡ V jet/Cs > 10, jet diameter = 5 cm, and jet length ~20 cm. Experiments to date have focused on the study of merging-jet dynamics and the shocks that form as a result of the interaction, in both collisional and collisionless regimes with respect to the inter-jet classical ion mean free path, and with and without an applied magnetic field. However, many other studies are also possible, as discussed in this paper.

  3. Research on Plasma Synthetic Jet Actuator

    NASA Astrophysics Data System (ADS)

    Che, X. K.; Nie, W. S.; Hou, Z. Y.

    2011-09-01

    Circular dielectric barrier surface discharge (DBDs) actuator is a new concept of zero mass synthetic jet actuator. The characteristic of discharge and flow control effect of annular-circular plasma synthetic jet actuator has been studied by means of of numerical simulation and experiment. The discharge current density, electron density, electrostatic body force density and flowfield have been obtained. The results show annular-circular actuator can produce normal jet whose velocity will be greater than 2.0 m/s. The jet will excite circumfluence. In order to insure the discharge is generated in the exposed electrode annular and produce centripetal and normal electrostatic body force, the width and annular diameter of exposed electrode must be big enough, or an opposite phase drove voltage potential should be applied between the two electrodes.

  4. Large area atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S.; Henins, Ivars; Babayan, Steve E.; Hicks, Robert F.

    2001-01-01

    Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

  5. Dense Hypervelocity Plasma Jets for Fusion Applications

    NASA Astrophysics Data System (ADS)

    Witherspoon, F. Douglas; Thio, Y. C. Francis

    2005-10-01

    High velocity dense plasma jets are being developed for a variety of fusion applications, including refueling, disruption mitigation, High Energy Density Plasmas, magnetized target/magneto-inertial fusion, injection of angular momentum into centrifugally confined mirrors, and others. The technical goal is to accelerate plasma blobs of density >10^17 cm-3 and total mass >100 micrograms to velocities >200 km/s. The approach utilizes symmetrical injection of very high density plasma into a coaxial EM accelerator having a tailored cross-section that prevents formation of the blow-by instability. AFRL MACH2 modeling identified 2 electrode configurations that produce the desired plasma jet parameters. The injected plasma is generated by up to 64 radially oriented capillary discharges arranged uniformly around the circumference of an angled annular injection section. Initial experimental results are presented in which 8 capillaries are fired in parallel with jitter of ˜100 ns. Current focus is on higher voltage operation to reduce jitter to a few 10's of ns, and development of a suite of optical and spectroscopic plasma diagnostics.

  6. Artificial plasma jet in the ionosphere

    NASA Astrophysics Data System (ADS)

    Haerendel, G.; Sagdeev, R. Z.

    The dynamics of an artificially injected plasma beam in the near-earth space are analyzed in terms of the beam structure, its propagation across the magnetic field, and the resulting wave phenomena (Porcupine Project, flight 4, March 31, 1979). Out of the four ejectable canisters attached to the main payload, two were instrumented by the U.S., one by the USSR (the Xenon plasma beam experiment), and one by West Germany (carrying a barium ion jet experiment). The propagation of the plasma seems to occur in three stages, with high-frequency broad-band oscillations mainly localized in the 'core' of the jet, while low-frequency oscillations were spatially separated from it. The generation region of LF oscillations was found to be much wider than the jet core. As a result of the interaction between the plasma beam and the ambient medium a heating of electrons, up to energies of about 20 eV, associated with LF noise was observed. The behavior of high-energy ions and the observed HF wave phenomena need further analysis.

  7. Laboratory plasma physics experiments using merging supersonic plasma jets

    DOE PAGESBeta

    Hsu, S. C.; Moser, A. L.; Merritt, E. C.; Adams, C. S.; Dunn, J. P.; Brockington, S.; Case, A.; Gilmore, M.; Lynn, A. G.; Messer, S. J.; et al

    2015-04-01

    We describe a laboratory plasma physics experiment at Los Alamos National Laboratory that uses two merging supersonic plasma jets formed and launched by pulsed-power-driven railguns. The jets can be formed using any atomic species or mixture available in a compressed-gas bottle and have the following nominal initial parameters at the railgun nozzle exit: ne ≈ ni ~ 10¹⁶ cm⁻³, Te ≈ Ti ≈ 1.4 eV, Vjet ≈ 30–100 km/s, mean chargemore » $$\\bar{Z}$$ ≈ 1, sonic Mach number Ms ≡ Vjet/Cs > 10, jet diameter = 5 cm, and jet length ≈ 20 cm. Experiments to date have focused on the study of merging-jet dynamics and the shocks that form as a result of the interaction, in both collisional and collisionless regimes with respect to the inter-jet classical ion mean free path, and with and without an applied magnetic field. However, many other studies are also possible, as discussed in this paper.« less

  8. Plasma diagnostics of non-equilibrium atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

    Shashurin, Alexey; Scott, David; Keidar, Michael; Shneider, Mikhail

    2014-10-01

    Intensive development and biomedical application of non-equilibrium atmospheric plasma jet (NEAPJ) facilitates rapid growth of the plasma medicine field. The NEAPJ facility utilized at the George Washington University (GWU) demonstrated efficacy for treatment of various cancer types (lung, bladder, breast, head, neck, brain and skin). In this work we review recent advances of the research conducted at GWU concerned with the development of NEAPJ diagnostics including Rayleigh Microwave Scattering setup, method of streamer scattering on DC potential, Rogowski coils, ICCD camera and optical emission spectroscopy. These tools allow conducting temporally-resolved measurements of plasma density, electrical potential, charge and size of the streamer head, electrical currents flowing though the jet, ionization front propagation speed etc. Transient dynamics of plasma and discharge parameters will be considered and physical processes involved in the discharge will be analyzed including streamer breakdown, electrical coupling of the streamer tip with discharge electrodes, factors determining NEAPJ length, cross-sectional shape and propagation path etc.

  9. MHD Simulations of Thermal Plasma Jets in Coaxial Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Subramaniam, Vivek; Raja, Laxminarayan

    2015-09-01

    The development of a magneto-hydrodynamics (MHD) numerical tool to study high energy density thermal plasma in coaxial plasma accelerators is presented. The coaxial plasma accelerator is a device used simulate the conditions created at the confining wall of a thermonuclear fusion reactor during an edge localized mode (ELM) disruption event. This is achieved by creating magnetized thermal plasma in a coaxial volume which is then accelerated by the Lorentz force to form a high velocity plasma jet. The simulation tool developed solves the resistive MHD equation using a finite volume method (FVM) framework. The acceleration and subsequent demagnetization of the plasma as it travels down the length of the accelerator is simulated and shows good agreement with experiments. Additionally, a model to study the thermalization of the plasma at the inlet is being developed in order to give self-consistent initial conditions to the MHD solver.

  10. Magnetized plasma jets in experiment and simulation

    NASA Astrophysics Data System (ADS)

    Schrafel, Peter; Greenly, John; Gourdain, Pierre; Seyler, Charles; Blesener, Kate; Kusse, Bruce

    2013-10-01

    This research focuses on the initial ablation phase of a thing (20 micron) Al foil driven on the 1 MA-in-100 ns COBRA through a 5 mm diameter cathode in a radial configuration. In these experiments, ablated surface plasma (ASP) on the top of the foil and a strongly collimated axial plasma jet can be observed developing midway through current-rise. Our goal is to establish the relationship between the ASP and the jet. These jets are of interest for their potential relevance to astrophysical phenomena. An independently pulsed 200 μF capacitor bank with a Helmholtz coil pair allows for the imposition of a slow (150 μs) and strong (~1 T) axial magnetic field on the experiment. Application of this field eliminates significant azimuthal asymmetry in extreme ultraviolet emission of the ASP. This asymmetry is likely a current filamentation instability. Laser-backlit shadowgraphy and interferometry confirm that the jet-hollowing is correlated with the application of the axial magnetic field. Visible spectroscopic measurements show a doppler shift consistent with an azimuthal velocity in the ASP caused by the applied B-field. Computational simulations with the XMHD code PERSEUS qualitatively agree with the experimental results.

  11. Living tissue under treatment of cold plasma atmospheric jet

    SciTech Connect

    Shashurin, A.; Keidar, M.; Bronnikov, S.; Jurjus, R. A.; Stepp, M. A.

    2008-11-03

    The interaction of the cold atmospheric plasma jet with fibroblast cells was studied. Plasma jet was initiated in the helium flow blowing through the syringe by application of high ac voltage to the discharge electrodes. The plasma jet had a length of 5 cm and a diameter of 1.5-2 mm in ambient air. Treatment of cells with plasma jet resulted in decreasing of cell migration rate, cell detachment, and appearance of ''frozen'' cells, while treatment with helium flow (no plasma) resulted in appearance of frozen cells only. A variety of cellular responses was explained by different intensities of treatment.

  12. Magnetized laboratory plasma jets: Experiment and simulation

    NASA Astrophysics Data System (ADS)

    Schrafel, Peter; Bell, Kate; Greenly, John; Seyler, Charles; Kusse, Bruce

    2015-01-01

    Experiments involving radial foils on a 1 M A , 100 n s current driver can be used to study the ablation of thin foils and liners, produce extreme conditions relevant to laboratory astrophysics, and aid in computational code validation. This research focuses on the initial ablation phase of a 20 μ m Al foil (8111 alloy), in a radial configuration, driven by Cornell University's COBRA pulsed power generator. In these experiments ablated surface plasma (ASP) on the top side of the foil and a strongly collimated axial plasma jet are observed developing midway through the current rise. With experimental and computational results this work gives a detailed description of the role of the ASP in the formation of the plasma jet with and without an applied axial magnetic field. This ˜1 T field is applied by a Helmholtz-coil pair driven by a slow, 150 μ s current pulse and penetrates the load hardware before arrival of the COBRA pulse. Several effects of the applied magnetic field are observed: (1) without the field extreme-ultraviolet emission from the ASP shows considerable azimuthal asymmetry while with the field the ASP develops azimuthal motion that reduces this asymmetry, (2) this azimuthal motion slows the development of the jet when the field is applied, and (3) with the magnetic field the jet becomes less collimated and has a density minimum (hollowing) on the axis. PERSEUS, an XMHD code, has qualitatively and quantitatively reproduced all these experimental observations. The differences between this XMHD and an MHD code without a Hall current and inertial effects are discussed. In addition the PERSEUS results describe effects we were not able to resolve experimentally and suggest a line of future experiments with better diagnostics.

  13. Magnetized laboratory plasma jets: experiment and simulation.

    PubMed

    Schrafel, Peter; Bell, Kate; Greenly, John; Seyler, Charles; Kusse, Bruce

    2015-01-01

    Experiments involving radial foils on a 1 MA, 100 ns current driver can be used to study the ablation of thin foils and liners, produce extreme conditions relevant to laboratory astrophysics, and aid in computational code validation. This research focuses on the initial ablation phase of a 20 μm Al foil (8111 alloy), in a radial configuration, driven by Cornell University's COBRA pulsed power generator. In these experiments ablated surface plasma (ASP) on the top side of the foil and a strongly collimated axial plasma jet are observed developing midway through the current rise. With experimental and computational results this work gives a detailed description of the role of the ASP in the formation of the plasma jet with and without an applied axial magnetic field. This ∼1 T field is applied by a Helmholtz-coil pair driven by a slow, 150 μs current pulse and penetrates the load hardware before arrival of the COBRA pulse. Several effects of the applied magnetic field are observed: (1) without the field extreme-ultraviolet emission from the ASP shows considerable azimuthal asymmetry while with the field the ASP develops azimuthal motion that reduces this asymmetry, (2) this azimuthal motion slows the development of the jet when the field is applied, and (3) with the magnetic field the jet becomes less collimated and has a density minimum (hollowing) on the axis. PERSEUS, an XMHD code, has qualitatively and quantitatively reproduced all these experimental observations. The differences between this XMHD and an MHD code without a Hall current and inertial effects are discussed. In addition the PERSEUS results describe effects we were not able to resolve experimentally and suggest a line of future experiments with better diagnostics. PMID:25679726

  14. Electron dynamics and plasma jet formation in a helium atmospheric pressure dielectric barrier discharge jet

    SciTech Connect

    Algwari, Q. Th.; O'Connell, D.

    2011-09-19

    The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of the dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.

  15. Dynamics of filamentary plasma jets used in plasma medicine

    NASA Astrophysics Data System (ADS)

    Reuter, Stephan

    2015-09-01

    Atmospheric plasmas exhibit large gradients in space and time. This challenges diagnostics such as LIF or other quantitative species detection methods. Single shot and 2D measurements can supply information otherwise hidden in averaging single point measurements. Especially the interaction of jet like plasmas with ambient surroundings poses unmet challenges. In the present work, several approaches of laser diagnostics of plasma and gas phase combined with numerical simulation sow how a careful study of the plasma initiated processes can lead to an at least partial understanding of plasma interaction with liquid and biological systems. In collaboration with Ansgar Schmidt-Bleker, INP Greifswald e.V.; Sylvain Iseni, GREMI, UMR 7344, CNRS/Université d'Orléans and Jörn Winter, Helena Jablonowski, and Klaus-Dieter Weltmann, INP Greifswald e.V. BMBF FKZ 03Z2DN12.

  16. Plasma waves and jets from moving conductors

    NASA Astrophysics Data System (ADS)

    Gralla, Samuel E.; Zimmerman, Peter

    2016-06-01

    We consider force-free plasma waves launched by the motion of conducting material through a magnetic field. We develop a spacetime-covariant formalism for perturbations of a uniform magnetic field and show how the transverse motion of a conducting fluid acts as a source. We show that fast-mode waves are sourced by the compressibility of the fluid, with incompressible fluids launching a pure-Alfvén outflow. Remarkably, this outflow can be written down in closed form for an arbitrary time-dependent, nonaxisymmetric incompressible flow. The instantaneous flow velocity is imprinted on the magnetic field and transmitted away at the speed of light, carrying detailed information about the conducting source at the time of emission. These results can be applied to transients in pulsar outflows and to jets from neutron stars orbiting in the magnetosphere of another compact object. We discuss jets from moving conductors in some detail.

  17. Magnetized and collimated millimeter scale plasma jets with astrophysical relevance

    SciTech Connect

    Brady, Parrish C.; Quevedo, Hernan J.; Valanju, Prashant M.; Bengtson, Roger D.; Ditmire, Todd

    2012-01-15

    Magnetized collimated plasma jets are created in the laboratory to extend our understanding of plasma jet acceleration and collimation mechanisms with particular connection to astrophysical jets. In this study, plasma collimated jets are formed from supersonic unmagnetized flows, mimicking a stellar wind, subject to currents and magnetohydrodynamic forces. It is found that an external poloidal magnetic field, like the ones found anchored to accretion disks, is essential to stabilize the jets against current-driven instabilities. The maximum jet length before instabilities develop is proportional to the field strength and the length threshold agrees well with Kruskal-Shafranov theory. The plasma evolution is modeled qualitatively using MHD theory of current-carrying flux tubes showing that jet acceleration and collimation arise as a result of electromagnetic forces.

  18. Plasma Jet Experiments Using LULI 2000 Laser Facility

    NASA Astrophysics Data System (ADS)

    Loupias, B.; Falize, E.; Koenig, M.; Bouquet, S.; Ozaki, N.; Benuzzi-Mounaix, A.; Michaut, C.; Goahec, M. Rabec Le; Nazarov, W.; Courtois, C.; Aglitskiy, Y.; Faenov, A. Ya.; Pikuz, T.

    2007-01-01

    We present experiments performed with the LULI2000 nanosecond laser facility. We generated plasma jets by using specific designed target. The main measured quantities related to the jet such as its propagation velocity, temperature and emissive radius evolution are presented. We also performed analytical work, which explains the jet evolution in some cases.

  19. A theory of MHD instability of an inhomogeneous plasma jet

    NASA Astrophysics Data System (ADS)

    Leonovich, Anatoly S.

    2011-06-01

    A problem of the stability of an inhomogeneous axisymmetric plasma jet in a parallel magnetic field is solved. The jet boundary becomes, under certain conditions, unstable relative to magnetosonic oscillations (Kelvin-Helmholtz instability) in the presence of a shear flow at the jet boundary. Because of its internal inhomogeneity the plasma jet has resonance surfaces, where conversion takes place between various modes of plasma magnetohydrodynamic (MHD) oscillations. Propagating in inhomogeneous plasma, fast magnetosonic waves drive the Alfven and slow magnetosonic (SMS) oscillations, tightly localized across the magnetic shells, on the resonance surfaces. MHD oscillation energy is absorbed in the neighbourhood of these resonance surfaces. The resonance surfaces disappear for the eigenmodes of SMS waves propagating in the jet waveguide. The stability of the plasma MHD flow is determined by competition between the mechanisms of shear flow instability on the boundary and wave energy dissipation because of resonant MHD-mode coupling. The problem is solved analytically, in the Wentzel, Kramers, Brillouin (WKB) approximation, for the plasma jet with a boundary in the form of a tangential discontinuity over the radial coordinate. The Kelvin-Helmholtz instability develops if plasma flow velocity in the jet exceeds the maximum Alfven speed at the boundary. The stability of the plasma jet with a smooth boundary layer is investigated numerically for the basic modes of MHD oscillations, to which the WKB approximation is inapplicable. A new 'unstable mode of MHD oscillations has been discovered which, unlike the Kelvin-Helmholtz instability, exists for any, however weak, plasma flow velocities.

  20. Atmospheric pressure plasma jet for liquid spray treatment

    NASA Astrophysics Data System (ADS)

    Mitić, S.; Philipps, J.; Hofmann, D.

    2016-05-01

    Atmospheric pressure plasma jets have been intensively studied in recent years due to growing interest in their use for biomedical applications and surface treatments. Either surfaces can be treated by a plasma jet afterglow for cleaning or activation or a material can be deposited by a reactive gas component activated by plasma. Effects of plasma on liquid have been reported several times where the electron spin trapping method was used for radical detection. Here we propose another method of liquid treatment using the atmospheric pressure plasma jet. In the device presented here, liquid was sprayed in droplets from an inner electrode directly into a plasma jet where it was treated and sprayed out by gas flow. Optical end electrical measurements were done for diagnostics of the plasma while electron paramagnetic resonance measurements were used for detection of radicals (\\text{OH},\\text{OOH},\\text{CH} ) produced by plasma treatment of liquids.

  1. Electrical characteristics and formation mechanism of atmospheric pressure plasma jet

    SciTech Connect

    Liu, Lijuan; Zhang, Yu; Tian, Weijing; Meng, Ying; Ouyang, Jiting

    2014-06-16

    The behavior of atmospheric pressure plasma jet produced by a coplanar dielectric barrier discharge in helium in external electrostatic and magnetic field is investigated. Net negative charges in the plasma jet outside the tube were detected. The deflection of the plume in the external field was observed. The plasma jet is suggested to be formed by the electron beam from the temporal cathode which is accelerated by a longitudinal field induced by the surface charges on the dielectric tube or interface between the helium and ambient air. The helium flow is necessary for the jet formation in the surrounding air.

  2. Inductive and Electrostatic Acceleration in Relativistic Jet-Plasma Interactions

    SciTech Connect

    Ng, Johnny S.T.; Noble, Robert J.; /SLAC

    2005-07-13

    We report on the observation of rapid particle acceleration in numerical simulations of relativistic jet-plasma interactions and discuss the underlying mechanisms. The dynamics of a charge-neutral, narrow, electron-positron jet propagating through an unmagnetized electron-ion plasma was investigated using a three-dimensional, electromagnetic, particle-in-cell computer code. The interaction excited magnetic filamentation as well as electrostatic (longitudinal) plasma instabilities. In some cases, the longitudinal electric fields generated inductively and electrostatically reached the cold plasma wave-breaking limit, and the longitudinal momentum of about half the positrons increased by 50% with a maximum gain exceeding a factor of two. The results are relevant to understanding the micro-physics at the interface region of an astrophysical jet with the interstellar plasma, for example, the edge of a wide jet or the jet-termination point.

  3. Plasma Jet Simulations Using a Generalized Ohm's Law

    NASA Technical Reports Server (NTRS)

    Ebersohn, Frans; Shebalin, John V.; Girimaji, Sharath S.

    2012-01-01

    Plasma jets are important physical phenomena in astrophysics and plasma propulsion devices. A currently proposed dual jet plasma propulsion device to be used for ISS experiments strongly resembles a coronal loop and further draws a parallel between these physical systems [1]. To study plasma jets we use numerical methods that solve the compressible MHD equations using the generalized Ohm s law [2]. Here, we will discuss the crucial underlying physics of these systems along with the numerical procedures we utilize to study them. Recent results from our numerical experiments will be presented and discussed.

  4. Evolution of the Jet Opening Angle Distribution in Holographic Plasma

    NASA Astrophysics Data System (ADS)

    Rajagopal, Krishna; Sadofyev, Andrey V.; van der Schee, Wilke

    2016-05-01

    We use holography to analyze the evolution of an ensemble of jets, with an initial probability distribution for their energy and opening angle as in proton-proton (p p ) collisions, as they propagate through an expanding cooling droplet of strongly coupled plasma as in heavy ion collisions. We identify two competing effects: (i) each individual jet widens as it propagates and (ii) because wide-angle jets lose more energy, energy loss combined with the steeply falling perturbative spectrum serves to filter wide jets out of the ensemble at any given energy. Even though every jet widens, jets with a given energy can have a smaller mean opening angle after passage through the plasma than jets with that energy would have had in vacuum, as experimental data may indicate.

  5. Experimental results to study astrophysical plasma jets using Intense Lasers

    NASA Astrophysics Data System (ADS)

    Loupias, B.; Gregory, C. D.; Falize, E.; Waugh, J.; Seiichi, D.; Pikuz, S.; Kuramitsu, Y.; Ravasio, A.; Bouquet, S.; Michaut, C.; Barroso, P.; Rabec Le Gloahec, M.; Nazarov, W.; Takabe, H.; Sakawa, Y.; Woolsey, N.; Koenig, M.

    2009-08-01

    We present experimental results of plasma jet, interacted with an ambient medium, using intense lasers to investigate the complex features of astrophysical jets. This experiment was performed in France at the LULI facility, Ecole Polytechnique, using one long pulse laser to generate the jet and a short pulse laser to probe it by proton radiography. A foam filled cone target was used to generate high velocity plasma jet, and a gas jet nozzle produced the well known ambient medium. Using visible pyrometry and interferometry, we were able to measure the jet velocity and electronic density. We get a panel of measurements at various gas density and time delay. From these measurements, we could underline the growth of a perturbed shape of the jet interaction with the ambient medium. The reason of this last observation is still in debate and will be presented in the article.

  6. Evolution of the Jet Opening Angle Distribution in Holographic Plasma.

    PubMed

    Rajagopal, Krishna; Sadofyev, Andrey V; van der Schee, Wilke

    2016-05-27

    We use holography to analyze the evolution of an ensemble of jets, with an initial probability distribution for their energy and opening angle as in proton-proton (pp) collisions, as they propagate through an expanding cooling droplet of strongly coupled plasma as in heavy ion collisions. We identify two competing effects: (i) each individual jet widens as it propagates and (ii) because wide-angle jets lose more energy, energy loss combined with the steeply falling perturbative spectrum serves to filter wide jets out of the ensemble at any given energy. Even though every jet widens, jets with a given energy can have a smaller mean opening angle after passage through the plasma than jets with that energy would have had in vacuum, as experimental data may indicate. PMID:27284647

  7. Reactivity zones around an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Birer, Özgür

    2015-11-01

    The reactivity zones around an atmospheric pressure plasma jet are revealed by XPS mapping of chemical moieties on a polyethylene surface treated with a 3-mm plasma jet. The area directly hit by the helium plasma jet initially oxidizes and later etches away as the plasma treatment continues. The oxidation initially starts at the center and expands outwards as a ring pattern with different spatial potency. At the end of 10 min plasma jet treatment, distinct ring patterns for -NO, -COO, -CO and -NO3 species can be detected with respectively increasing diameters. The plasma jet can cause chemical changes at locations several millimeters away from the center. The spatial distribution of oxidized species suggests presence of chemical reactivity zones. Introduction of nitrogen into the helium plasma jet, not only increases the type of nitrogen moieties, but enriches the reactivity zones by generating nitrogen molecular ions within the plasma jet. The complex competing reaction mechanisms among the radicals, ions, metastable atoms and UV photons lead to unusual etching patterns on the surfaces.

  8. Cellular membrane collapse by atmospheric-pressure plasma jet

    SciTech Connect

    Kim, Kangil; Sik Yang, Sang E-mail: ssyang@ajou.ac.kr; Jun Ahn, Hak; Lee, Jong-Soo E-mail: ssyang@ajou.ac.kr; Lee, Jae-Hyeok; Kim, Jae-Ho

    2014-01-06

    Cellular membrane dysfunction caused by air plasma in cancer cells has been studied to exploit atmospheric-pressure plasma jets for cancer therapy. Here, we report that plasma jet treatment of cervical cancer HeLa cells increased electrical conductivity across the cellular lipid membrane and caused simultaneous lipid oxidation and cellular membrane collapse. We made this finding by employing a self-manufactured microelectrode chip. Furthermore, increased roughness of the cellular lipid membrane and sequential collapse of the membrane were observed by atomic force microscopy following plasma jet treatment. These results suggest that the cellular membrane catastrophe occurs via coincident altered electrical conductivity, lipid oxidation, and membrane roughening caused by an atmospheric-pressure plasma jet, possibly resulting in cellular vulnerability to reactive species generated from the plasma as well as cytotoxicity to cancer cells.

  9. Depolarization of subalfvenic plasma jet generating field-aligned currents

    NASA Astrophysics Data System (ADS)

    Sobyanin, D. B.; Gavrilov, B. G.; Podgorny, I. M.

    2004-01-01

    The subalfvenic magnetized plasma jet propagating across the geomagnetic field generates the field-aligned currents in ionospheric plasma. The transverse polarization electric field Ep = - V × B in the jet is reduced due to a leakage of polarization charges through the field-aligned currents (plasma jet depolarization). These phenomena are investigated in the laboratory experiment. It was revealed that the depolarization is accompanied by appearing of the electric field Ea along the plasma velocity vector and creation of an additional pair of the field-aligned currents being generated at the leading and trailing edge of the moving plasma. The value of Ea is comparable with the transverse electric field Ep. The depolarization results in the plasma jet deflection. The possibility of a manifestation of these effects in the NORTH STAR Russian-American active rocket experiment is discussed.

  10. Experimental studies of collisional plasma shocks and plasma interpenetration via merging supersonic plasma jets

    NASA Astrophysics Data System (ADS)

    Hsu, S. C.; Moser, A. L.; Merritt, E. C.; Adams, C. S.

    2015-11-01

    Over the past 4 years on the Plasma Liner Experiment (PLX) at LANL, we have studied obliquely and head-on-merging supersonic plasma jets of an argon/impurity or hydrogen/impurity mixture. The jets are formed/launched by pulsed-power-driven railguns. In successive experimental campaigns, we characterized the (a) evolution of plasma parameters of a single plasma jet as it propagated up to ~ 1 m away from the railgun nozzle, (b) density profiles and 2D morphology of the stagnation layer and oblique shocks that formed between obliquely merging jets, and (c) collisionless interpenetration transitioning to collisional stagnation between head-on-merging jets. Key plasma diagnostics included a fast-framing CCD camera, an 8-chord visible interferometer, a survey spectrometer, and a photodiode array. This talk summarizes the primary results mentioned above, and highlights analyses of inferred post-shock temperatures based on observations of density gradients that we attribute to shock-layer thickness. We also briefly describe more recent PLX experiments on Rayleigh-Taylor-instability evolution with magnetic and viscous effects, and potential future collisionless shock experiments enabled by low-impurity, higher-velocity plasma jets formed by contoured-gap coaxial guns. Supported by DOE Fusion Energy Sciences and LANL LDRD.

  11. Cold atmospheric pressure air plasma jet for medical applications

    NASA Astrophysics Data System (ADS)

    Kolb, J. F.; Mohamed, A.-A. H.; Price, R. O.; Swanson, R. J.; Bowman, A.; Chiavarini, R. L.; Stacey, M.; Schoenbach, K. H.

    2008-06-01

    By flowing atmospheric pressure air through a direct current powered microhollow cathode discharge, we were able to generate a 2cm long plasma jet. With increasing flow rate, the flow becomes turbulent and temperatures of the jet are reduced to values close to room temperature. Utilizing the jet, yeast grown on agar can be eradicated with a treatment of only a few seconds. Conversely, animal studies show no skin damage even with exposures ten times longer than needed for pathogen extermination. This cold plasma jet provides an effective mode of treatment for yeast infections of the skin.

  12. Supersonic gas jets for laser-plasma experiments

    NASA Astrophysics Data System (ADS)

    Schmid, K.; Veisz, L.

    2012-05-01

    We present an in-depth analysis of De Laval nozzles, which are ideal for gas jet generation in a wide variety of experiments. Scaling behavior of parameters especially relevant to laser-plasma experiments as jet collimation, sharpness of the jet edges and Mach number of the resulting jet is studied and several scaling laws are given. Special attention is paid to the problem of the generation of microscopic supersonic jets with diameters as small as 150 μm. In this regime, boundary layers dominate the flow formation and have to be included in the analysis.

  13. Liquid gallium jet-plasma interaction studies in ISTTOK tokamak

    NASA Astrophysics Data System (ADS)

    Gomes, R. B.; Fernandes, H.; Silva, C.; Sarakovskis, A.; Pereira, T.; Figueiredo, J.; Carvalho, B.; Soares, A.; Duarte, P.; Varandas, C.; Lielausis, O.; Klyukin, A.; Platacis, E.; Tale, I.; Alekseyv, A.

    2009-06-01

    Liquid metals have been pointed out as a suitable solution to solve problems related to the use of solid walls submitted to high power loads allowing, simultaneously, an efficient heat exhaustion process from fusion devices. The most promising candidate materials are lithium and gallium. However, lithium has a short liquid state temperature range when compared with gallium. To explore further this property, ISTTOK tokamak is being used to test the interaction of a free flying liquid gallium jet with the plasma. ISTTOK has been successfully operated with this jet without noticeable discharge degradation and no severe effect on the main plasma parameters or a significant plasma contamination by liquid metal. Additionally the response of an infrared sensor, intended to measure the jet surface temperature increase during its interaction with the plasma, has been studied. The jet power extraction capability is extrapolated from the heat flux profiles measured in ISTTOK plasmas.

  14. Three electrode atmospheric pressure plasma jet in helium flow

    NASA Astrophysics Data System (ADS)

    Maletic, Dejan; Puac, Nevena; Malovic, Gordana; Petrovic, Zoran Lj.

    2015-09-01

    Plasma jets are widely used in various types of applications and lately more and more in the field of plasma medicine. However, it is not only their applicability that distinguishes them from other atmospheric plasma sources, but also the behavior of the plasma. It was shown that plasma plume is not continuous, but discrete set of plasma packages. Here we present iCCD images and current voltage characteristics of a three electrode plasma jet. Our plasma jet has a simple design with body made of glass tube and two transparent electrodes wrapped around it. The additional third metal tip electrode was positioned at 10 and 25 mm in front of the jet nozzle and connected to the same potential as the powered electrode. Power transmitted to the plasma was from 0.5 W to 4.0 W and the helium flow rate was kept constant at 4 slm. For the 10 mm configuration plasma is ignited on the metal tip in the whole period of the excitation signal and in the positive half cycle plasma ``bullet'' is propagating beyond the metal tip. In contrast to that, for the 25 mm configuration at the tip electrode plasma can be seen only in the minimum and maximum of the excitation signal, and there is no plasma ``bullet'' formation. This research has been supported by the Ministry of Education, Science and Technological Development, Republic of Serbia, under projects ON171037 and III41011.

  15. The study of a plasma jet injected by an on-board plasma thruster

    NASA Astrophysics Data System (ADS)

    Grebnev, I. A.; Ivanov, G. V.; Khodnenko, V. P.; Morozov, A. I.; Perkov, I. A.; Pertsev, A. A.; Romanovskii, Iu. A.; Rylov, Iu. P.; Shishkin, G. G.; Trifonov, Iu. V.

    The injection of a steady plasma jet into the ionosphere results in interactions which were studied in experiments conducted onboard two Meteor satellites in 1977-1979. The jet parameters at the propulsion system output were as follows: propulsive mass: Xe; Xe (+) ion density at the nozzle section; 3 x 10 to the 11th per cu cm; plasma stream divergence: 20 degrees; jet velocity: 10-12 km/cm; ion energy: 130 eV; electron temperature: 1 + 3 eV. A Bennett-type modified radio-frequency mass-spectrometer and a two-channel electromagnetic wave analyzer were used for the measurements. It was found that (1) the injected plasma jet propagation depends on the jet injection pitch angle; (2) when the plasma jet was injected along the magnetic field, impactless jet spreading took place without considerable interaction with the ionospheric plasma; (3) when the plasma jet was injected across the magnetic field, considerable interaction was observed between the plasma jet/ionospheric plasma and the earth's magnetic field; and (4) electromagnetic fields were generated near the satellite by plasma jet interaction.

  16. Laboratory Studies of Supersonic Magnetized Plasma Jets and Radiative Shocks

    NASA Astrophysics Data System (ADS)

    Lebedev, Sergey

    2013-06-01

    In this talk I will focus on laboratory plasma experiments producing magnetically driven supersonic plasma jets and on the interaction of these jets with ambient media. The experiments are scalable to astrophysical flows in that the critical dimensionless numbers such as the plasma collisionality, the plasma beta, the Reynolds number and the magnetic Reynolds number are all in the astrophysically appropriate ranges. The experimental results will be compared with computer simulations performed with laboratory plasma codes and with astrophysical codes. In the experiments the jets are driven and collimated by the toroidal magnetic fields and it is found that the level of MHD instabilities in the jets strongly depends on the strength of the field represented by the ratio of the thermal to magnetic field pressures (plasma beta). The experiments show the possibility of formation of episodic outflows, with periodic ejections of magnetic bubbles naturally evolving into a heterogeneous jet propagating inside a channel made of self-collimated magnetic cavities [1,2]. We also found that it is possible to form quasi-laminar jets which are “indirectly” collimated by the toroidal magnetic fields, but this requires the presence of the lower density halo plasma surrounding the central jet [3]. Studies of the radiative shocks formed in the interaction of the supersonic magnetized plasma flows with ambient plasma will be also presented, and the development of cooling instabilities in the post-shock plasma will be discussed. This research was sponsored by EPSRC Grant No. EP/G001324/1 and by the OFES DOE under DOE Cooperative Agreement No. DE-SC-0001063. References 1. A. Ciardi, S.V. Lebedev, A. Frank et al., The Astrophysical Journal, 691: L147-L150 (2009) 2. F.A. Suzuki-Vidal, S.V. Lebedev, S.N. Bland et al., Physics of Plasmas, 17, 112708 (2010). 3. F.A. Suzuki-Vidal, M. Bocchi, S.V. Lebedev et al., Physics of Plasmas, 19, 022708 (2012).

  17. Experimental characterization of an argon laminar plasma jet at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Langlois-Bertrand, Emilie; de Izarra, Charles

    2011-10-01

    This paper deals with a dc laminar pure argon plasma jet operating at atmospheric pressure in ambient air that was experimentally studied in order to obtain temperature and velocity. Plasma jet temperature was evaluated by optical emission spectroscopy and the plasma jet velocity was determined by various methods using a pressure sensor. It is shown that the maximum plasma jet temperature is 15 000 K and the maximum plasma jet velocity is 250 m s-1 at the plasma jet centre. Finally, a study of the ambient air amount entrained into the plasma jet is presented.

  18. The effect of working gas impurities on plasma jets

    SciTech Connect

    Liu, X. Y.; He, M. B.; Liu, D. W.

    2015-04-15

    Air intrusion reduced the purity of working gas inside the tube for plasma jet, and thereby, affected the discharge dynamics. In this paper, the effect of using working gas with different purity level (helium purity 99.99999%, 99.99%, 99.9%, and 99%) on photoionization and the chemical reactivity of plasma jet were studied using a 2 dimensional plasma jet model. Photoionization of air species acted as a source of pre-ionization in front of the ionization region, which facilitated the transition from localized discharge to streamers inside the tube. The density of reactive species inside the tube was found to increase with the concentration of working gas impurities. For the highest purity helium (99.99999%), despite a low photoionization rate and the distance between the photoionization region and ionization region inside the tube, by increasing the applied voltage and decreasing the distance between the electrode and nozzle, plasma jets were formed.

  19. Etching of silicon surfaces using atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

    Paetzelt, H.; Böhm, G.; Arnold, Th

    2015-04-01

    Local plasma-assisted etching of crystalline silicon by fine focused plasma jets provides a method for high accuracy computer controlled surface waviness and figure error correction as well as free form processing and manufacturing. We investigate a radio-frequency powered atmospheric pressure He/N2/CF4 plasma jet for the local chemical etching of silicon using fluorine as reactive plasma gas component. This plasma jet tool has a typical tool function width of about 0.5 to 1.8 mm and a material removal rate up to 0.068 mm3 min-1. The relationship between etching rate and plasma jet parameters is discussed in detail regarding gas composition, working distance, scan velocity and RF power. Surface roughness after etching was characterized using atomic force microscopy and white light interferometry. A strong smoothing effect was observed for etching rough silicon surfaces like wet chemically-etched silicon wafer backsides. Using the dwell-time algorithm for a deterministic surface machining by superposition of the local removal function of the plasma tool we show a fast and efficient way for manufacturing complex silicon structures. In this article we present two examples of surface processing using small local plasma jets.

  20. Radiatively driven plasma jets around compact objects

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Indranil; Chakrabarti, Sandip K.

    2002-06-01

    Matter accreting on to black holes may develop shocks due to the centrifugal barrier. Some of the inflowing matter in the post-shock flow is deflected along the axis in the form of jets. Post-shock flow which behaves like a Compton cloud has `hot' electrons emitting high-energy photons. We study the effect of these `hot' photons on the outflowing matter. Radiation from this region could accelerate the outflowing matter, but radiation pressure should also slow it down. We show that the radiation drag restricts the flow from attaining a very high velocity. We introduce the concept of an `equilibrium velocity' (veq~0.5c), which sets the upper limit of the terminal velocity achieved by a cold plasma due to radiation deposition force in the absence of gravity. If the injection energy is Ein, then we find that the terminal velocity v∞ satisfies a relation v2<~veq2+2Ein.

  1. New Freeform Manufacturing Chains Based on Atmospheric Plasma Jet Machining

    NASA Astrophysics Data System (ADS)

    Arnold, T.; Boehm, G.; Paetzelt, H.

    2016-01-01

    New manufacturing chains for precise fabrication of asphere and freeform optical surfaces including atmospheric Plasma Jet Machining (PJM) technology will be presented. PJM is based on deterministic plasma-assisted material removal. It has the potential for flexible and cost-efficient shape generation and correction of small and medium-sized optical freeform elements. The paper discusses the interactions between the plasma tools and optical fused silica samples in the context of the pre-machined and intermediate surface states and identifies several plasma jet machining methods for freeform generation, surface correction, and finishing as well as suitable auxiliary polishing methods. The successful application of either processing chain is demonstrated.

  2. Model of the plasma jet originating from a cathode spot

    SciTech Connect

    Gavrilov, V.N.; Litvinov, E.A.; Mesyats, G.A.

    1995-12-31

    The 2-D NM model of the vacuum-arc plasma jet presented here is in outgrowth of the 1-D hydrodynamic model discussed by us. The computation carried out in 1-D approximation have provided the principal characteristics of a cathode jet being in satisfactory agreement with experimental data. Nevertheless, there results cannot be considered completely adequate, since actually the plum parameters of a cathode jet are distributed highly nonuniformly over its cross section. Furthermore, a 1-D model falls to take in to account the effects related to the influence of the self-magnetic field of the cathode jet.

  3. Astrophysical outflows simulated by laser-driven plasma jets

    NASA Astrophysics Data System (ADS)

    Michaut, C.; Gregory, C. D.; Loupias, B.; Falize, E.; Ravasio, A.; Dizière, A.; Vinci, T.; Koenig, M.; Bouquet, S.

    2011-02-01

    Within the framework of laboratory astrophysics, we form a qualified multidisciplinary group in radiative hydrodynamics. Since 10 years, we have developed laboratory experiments as radiative shocks and plasma jets in connection to astrophysics. Such laboratory experiments provide a unique opportunity to validate models and numerical schemes introduced in radiative hydrodynamics codes. Here we summarize our experimental researches about plasma jets. Laboratory astrophysical experiments have been performed using LULI2000 (France), VULCAN (UK) and GEKKO XII (Japan) intense lasers. The goal of these experiments is to investigate some of the complex features of jets from Young Stellar Objects (YSO), and in particular its interaction with the interstellar medium (ISM).

  4. Experiments on Injection of Dust Jets into Plasma

    SciTech Connect

    Dubinov, Alexander E.; Lvov, Igor L.; Sadovoi, Sergey A.; Selemir, Victor D.; Vyalykh, Dmitry V.

    2005-10-31

    Experimental technique for studying the injection of dust jets into plasma of a glow discharge in air based on a needle injector is developed. The velocity and flight time of a dust jet is measured under different initial conditions by laser method. Imprints of dust jets on adhesive films are obtained. It is shown that the propagation of 20-{mu}m dust grains in plasma is accompanied by self-contraction instability along and across the discharge, which leads to the dust agglomeration.

  5. Interfacial Stability of Converging Plasma Jets for Magnetized Target Fusion

    NASA Technical Reports Server (NTRS)

    Cassibry, J. T.; Thio, Y. C. F.; Wu, S. T.; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    The merging of a spherical distribution of plasma jets to dynamically form a gaseous liner has been proposed for use in magnetized target fusion propulsion. In this paper, a study is made of the interfacial stability of the interaction of these jets. Specifically, the Orr-Sommerfeld equation is integrated to obtain the growth rate of a perturbation to the primary flow at the interface between the colliding jets. The analysis lead to an estimate on the tolerances on the relative flow velocities of the merging plasma jets to form a stable, imploding liner. The results show that during the merging of the jets to form a liner and before contact with the target plasma the growth of the perturbed flow at the jet interface is not likely to destabilize the liner. These data suggest that, as far as the stability of the interface between the merging jets is concerned, the formation of liner can withstand velocity variation up to 50% between the neighboring jets over the density and temperature ranges investigated.

  6. Stability of liquid-nitrogen-jet laser-plasma targets

    NASA Astrophysics Data System (ADS)

    Fogelqvist, E.; Kördel, M.; Selin, M.; Hertz, H. M.

    2015-11-01

    Microscopic jets of cryogenic substances such as liquid nitrogen are important regenerative high-density targets for high-repetition rate, high-brightness laser-plasma soft x-ray sources. When operated in vacuum such liquid jets exhibit several non-classical instabilities that negatively influence the x-ray source's spatial and temporal stability, yield, and brightness, parameters that all are important for applications such as water-window microscopy. In the present paper, we investigate liquid-nitrogen jets with a flash-illumination imaging system that allows for a quantitative stability analysis with high spatial and temporal resolution. Direct and indirect consequences of evaporation are identified as the key reasons for the observed instabilities. Operating the jets in an approximately 100 mbar ambient atmosphere counteracts the effects of evaporation and produces highly stable liquid nitrogen jets. For operation in vacuum, which is necessary for the laser plasmas, we improve the stability by introducing an external radiative heating element. The method significantly extends the distance from the nozzle that can be used for liquid-jet laser plasmas, which is of importance for high-average-power applications. Finally, we show that laser-plasma operation with the heating-element-stabilized jet shows improved short-term and long-term temporal stability in its water-window x-ray emission.

  7. Stability of liquid-nitrogen-jet laser-plasma targets

    SciTech Connect

    Fogelqvist, E. Kördel, M.; Selin, M.; Hertz, H. M.

    2015-11-07

    Microscopic jets of cryogenic substances such as liquid nitrogen are important regenerative high-density targets for high-repetition rate, high-brightness laser-plasma soft x-ray sources. When operated in vacuum such liquid jets exhibit several non-classical instabilities that negatively influence the x-ray source's spatial and temporal stability, yield, and brightness, parameters that all are important for applications such as water-window microscopy. In the present paper, we investigate liquid-nitrogen jets with a flash-illumination imaging system that allows for a quantitative stability analysis with high spatial and temporal resolution. Direct and indirect consequences of evaporation are identified as the key reasons for the observed instabilities. Operating the jets in an approximately 100 mbar ambient atmosphere counteracts the effects of evaporation and produces highly stable liquid nitrogen jets. For operation in vacuum, which is necessary for the laser plasmas, we improve the stability by introducing an external radiative heating element. The method significantly extends the distance from the nozzle that can be used for liquid-jet laser plasmas, which is of importance for high-average-power applications. Finally, we show that laser-plasma operation with the heating-element-stabilized jet shows improved short-term and long-term temporal stability in its water-window x-ray emission.

  8. Background density channel generation by axial plasma jets

    NASA Astrophysics Data System (ADS)

    Bonde, Jeffrey; Vincena, Stephen; Gekelman, Walter

    2012-10-01

    The supersonic expansion of a dense plasma into an ambient plasma can be observed in phenomena ranging from coronal mass ejections and protostellar outflows to astrophysical jets. To produce a supersonic plasma jet in a laboratory setting, a laser-produced plasma explodes into an ambient argon plasma (n˜5.10^12cm-3,cs˜6.10^5cm/s,vA˜1.2.10^7cm/s) in the Large Plasma Device at UCLA. This study focuses on the initial formation and evolution of the jet and its effects on the background magnetized plasma. Using a laser-induced fluorescence diagnostic of Ar-II ions at their 611.5nm transition, the jet is seen to perturb the equilibrium population of the target argon ions. A CCD camera with a fast (>=3ns) shutter spatially and temporally resolves images of the fluorescence. Time-lapsed imaging shows an axially aligned channel of depleted fluorescence form near the source and travel with an undiminished speed characteristic of the jet (v/cs˜20) while remaining highly collimated. Langmuir probe measurements show a large ion flux moving in conjunction with the excited argon depletion after traveling more than an ion inertial length.

  9. Gas Flow and Electric Field Characterization in Plasma Jets for Biomedical Applications: From Single Jet to Multi Jet Arrays

    NASA Astrophysics Data System (ADS)

    Robert, Eric

    2015-09-01

    This work reports first on time-resolved measurement of longitudinal and radial electric fields (EF) associated with plasma propagation in dielectric capillaries. Plasma propagation occurs in a region where longitudinal EF exists ahead the ionization front position revealed from plasma emission with ICCD measurement. The ionization front propagation induces the sudden rise of a radial EF component. Both of these EF components have a few kV/cm in amplitude for helium or neon plasmas. Their amplitude is kept almost constant along a few tens of cm long capillary. The key role of the voltage pulse polarity and the drastic impact of the presence of a target in front of the plasma jet are discussed from Schlieren images. All these experimental measurements are in excellent agreement with model calculations which are used to infer EF data on capillary axis. EF diagnostics in the plasma plume in the free jet mode but also in contact with various targets is proposed. The combination of intense transient EF, both of ns and µs duration, together with significant transient reactive species generation during plasma jet treatments may be reconsidered. Typical EF amplitudes likely to induce electrostimulation, electroporation are indeed probably achieved in many in vivo protocols. Stimulation of tissue oxygenation, blood flow rate modulation and more recently immune system triggering may be examples where EF could play a significant role. The second part of this work is dedicated to the development of multi jets, using two different setups, based on a single plasma source. Plasma splitting in dielectric tubes drilled with sub millimetric orifices, but also plasma transfer across metallic tubes equipped with such orifices are analyzed from ICCD imaging and time resolved EF measurements. This allows for the design of plasma jet arrays but also emphasizes the necessity to account for voltage pulse polarity, target potential status, consecutive helium flow modulation and

  10. Experimental approaches for studying non-equilibrium atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

    Shashurin, A.; Keidar, M.

    2015-12-01

    This work reviews recent research efforts undertaken in the area non-equilibrium atmospheric plasma jets with special focus on experimental approaches. Physics of small non-equilibrium atmospheric plasma jets operating in kHz frequency range at powers around few Watts will be analyzed, including mechanism of breakdown, process of ionization front propagation, electrical coupling of the ionization front with the discharge electrodes, distributions of excited and ionized species, discharge current spreading, transient dynamics of various plasma parameters, etc. Experimental diagnostic approaches utilized in the field will be considered, including Rayleigh microwave scattering, Thomson laser scattering, electrostatic streamer scatterers, optical emission spectroscopy, fast photographing, etc.

  11. Experimental approaches for studying non-equilibrium atmospheric plasma jets

    SciTech Connect

    Shashurin, A.; Keidar, M.

    2015-12-15

    This work reviews recent research efforts undertaken in the area non-equilibrium atmospheric plasma jets with special focus on experimental approaches. Physics of small non-equilibrium atmospheric plasma jets operating in kHz frequency range at powers around few Watts will be analyzed, including mechanism of breakdown, process of ionization front propagation, electrical coupling of the ionization front with the discharge electrodes, distributions of excited and ionized species, discharge current spreading, transient dynamics of various plasma parameters, etc. Experimental diagnostic approaches utilized in the field will be considered, including Rayleigh microwave scattering, Thomson laser scattering, electrostatic streamer scatterers, optical emission spectroscopy, fast photographing, etc.

  12. Diagnostics of DC plasma jets generated with Laval anodes

    SciTech Connect

    Rahmane, M.; Soucy, G.; Boulos, M.I.; Henne, R.

    1995-12-31

    Plasma jets originating from d.c. torches equipped with Laval nozzles are considered to be more efficient for both vacuum and atmospheric plasma spraying than those generated with the standard cylindrical anodes. The present study is devoted to the measurement of the temperature and velocity fields in plasma jets resulting from three different nozzles: a cylindrical and two Laval anodes with nominal Mach numbers of 2.5 and 3. The enthalpy probe and emission spectroscopy techniques are used for this purpose. Attention is given to the effect of the chamber pressure on the distribution of the temperature and velocity fields. The results show that when Laval nozzles are used at reduced chamber pressure (200 torr), the jets are wider, with higher temperature and velocity values in the central regions, compared to those obtained using cylindrical anodes. These characteristics are expected to improve the results of plasma spraying processes with respect to the layer quality and deposition efficiency.

  13. Striation and plasma bullet propagation in an atmospheric pressure plasma jet

    SciTech Connect

    Kim, Sun Ja; Chung, T. H.; Bae, S. H.

    2010-05-15

    An atmospheric pressure plasma jet source driven by pulsed wave of several tens of kilohertz and by sinusoidal wave was designed and characterized. A newly designed jet consists of a sharpened tungsten pin electrode covered with a cone type Teflon layer confined in a Pyrex tube. This structure provides an efficient ignition since the electric field is concentrated on the end of electrode. Using the electrical and optical characterization, the properties of plasma bullet were explored. For the Ar plasma jet driven by a pulsed wave at low duty cycles, the volume, the speed, and the luminosity of the plasma bullet became larger, and the striation behavior was observed.

  14. Effect of a floating electrode on a plasma jet

    SciTech Connect

    Hu, J. T.; Wang, J. G.; Liu, X. Y.; Liu, D. W.; Lu, X. P.; Shi, J. J.; Ostrikov, K.

    2013-08-15

    Two kinds of floating electrode, floating dielectric barrier covered electrode (FDBCE) and floating pin electrode (FPE), which can enhance the performance of plasma jet are reported. The intense discharge between the floating electrode and power electrode decreased the voltage to trigger the plasma jet substantially. The transition of plasma bullet from ring shape to disk shape in the high helium concentration region happened when the floating electrode was totally inside the powered ring electrode. The enhanced electric field between propagating plasma bullet and ground electrode is the reason for this transition. The double plasma bullets happened when part of the FDBCE was outside the powered ring electrode, which is attributed to the structure and surface charge of FDBCE. As part of the FPE was outside the powered ring electrode, the return stroke resulted in a single intensified plasma channel between FPE and ground electrode.

  15. Dust generation at interaction of plasma jet with surfaces

    NASA Astrophysics Data System (ADS)

    Ticos, Catalin; Toader, Dorina; Banu, Nicoleta; Scurtu, Adrian; Oane, Mihai

    2013-10-01

    Coatings of W and C with widths of a few microns will be exposed to plasma jet for studying the erosion of the surface and detachment of micron size dust particles. A coaxial plasma gun has been built inside a vacuum chamber for producing supersonic plasma jets. Its design is based on a 50 kJ coaxial plasma gun which has been successfully used for accelerating hypervelocity dust. Initial shots were carried out for a capacitor bank with C = 12 μF and charged up to 2 kV. Currents of tens of amps were measured with a Rogowsky coil and plasma flow speeds of 4 km/s were inferred from high-speed images of jet propagation. An upgrade consisting in adding capacitors in parallel will be performed in order to increase the energy up to 2 kJ. A coil will be installed at the gun muzzle to compress the plasma flow and increase the energy density of the jet on the sample surface. A CCD camera with a maximum recording speed of 100 k fps and a maximum resolution of 1024 × 1024 pixels was set for image acquisition of the plasma and dust. A laser system used to illuminate the ejected dust from the surface includes a laser diode emitting at 650 nm with a beam power of 25 mW. The authors acknowledge support from EURATOM WP13-IPH-A03-P2-02-BS22.

  16. Jet broadening in unstable non-Abelian plasmas

    SciTech Connect

    Dumitru, Adrian; Schenke, Bjoern; Strickland, Michael; Nara, Yasushi

    2008-08-15

    We perform numerical simulations of the SU(2) Boltzmann-Vlasov equation including both hard elastic particle collisions and soft interactions mediated by classical Yang-Mills fields. Using this technique we calculate the momentum-space broadening of high-energy jets in real time for both locally isotropic and anisotropic plasmas. In both cases we introduce a separation scale that separates hard and soft interactions and demonstrate that our results for jet broadening are independent of the precise separation scale chosen. For an isotropic plasma this allows us to calculate the jet transport coefficient q-circumflex including hard and soft nonequilibrium dynamics. For an anisotropic plasma the jet transport coefficient becomes a tensor with q-circumflex{sub L}{ne}q-circumflex{sub perpendicular}. We find that for weakly coupled anisotropic plasmas the fields develop unstable modes, forming configurations where B{sub perpendicular}>E{sub perpendicular} and E{sub z}>B{sub z}, which lead to q-circumflex{sub L}>q-circumflex{sub perpendicular}. We study whether the effect is strong enough to explain the experimental observation that high-energy jets traversing the plasma perpendicular to the beam axis experience much stronger broadening in rapidity, {delta}{eta}, than in azimuth, {delta}{phi}.

  17. Parametric calculations of plasma jets generated by microdischarges

    NASA Astrophysics Data System (ADS)

    Foletto, M.; Boeuf, J. P.; Pitchford, L. C.

    2014-10-01

    ``Guided streamers'' or ``plasma jets'' can be generated in open air by applying rf or impulse voltages to a microdischarge through which there is a flow of helium. For flow conditions such that a helium column surrounded by air extends some distance (centimeters) past the exit of the microdischarge, a plasma jet can be initiated. Previous works have shown that this is essentially a streamer propagating in the easily-ionized helium column and impeded from branching by the surrounding air. For many applications, it is of interest to understand the parameters controlling the properties of the plasma jet. To this end, we present results from a series of parametric calculations using our previously published model to identify the influence of the microdischarge configuration on the generation, propagation, and properties of the plasma jet. We focus mainly on a geometry with hollow, concentric electrodes separated by a dielectric tube corresponding to the experiments of Douat et al., and we vary the dimensions and relative off-set of the electrodes, applying an impulse voltage or the experimental waveform to the inner electrode. For the same applied voltage waveform, parameters which influence the electric field and electron density in the plasma jet are the dielectric permittivity, the tube diameter, and the dielectric length. Support by the French National Research Agency project PAMPA.

  18. Atmospheric Pressure Non-Thermal Air Plasma Jet

    NASA Astrophysics Data System (ADS)

    Mohamed, Abdel-Aleam; Al-Mashraqi, Ahmed; Benghanem, Mohamed; Al Shariff, Samir

    2013-09-01

    Atmospheric pressure air cold plasma jet is introduced in this work. It is AC (60 Hz to 20 kHz) cold plasma jet in air. The system is consisted of a cylindrical alumina insulator tube with outer diameter of 1.59 mm and 26 mm length and 0.80 mm inner diameter. AC sinusoidal high voltage was applied to the powered electrode which is a hollow needle inserted in the Alumina tube. The inner electrode is a hollow needle with 0.80 mm and 0.46 mm outer and inner diameters respectively. The outer electrode is grounded which is a copper ring surrounded the alumina tube locates at the nozzle end. Air is blowing through the inner electrode to form a plasma jet. The jet length increases with flow rate and applied voltage to reach 1.5 cm. The gas temperature decreases with distance from the end of the nozzle and with increasing the flow rate. The spectroscopic measurement between 200 nm and 900 nm indicates that the jet contains reactive species such as OH, O in addition to the UV emission. The peak to peak current values increased from 6 mA to 12 mA. The current voltage waveform indicates that the generated jet is homogenous plasma. The jet gas temperature measurements indicate that the jet has a room temperature. This work was supported by the National Science, Technology and Innovation Plan(NSTIP) through the Science and Technology Unit (STU) at Taibah University, Al Madinah Al Munawwarah, KSA, with the grant number 08-BIO24-5.

  19. Interaction of a Liquid Gallium Jet with ISTTOK Edge Plasmas

    NASA Astrophysics Data System (ADS)

    Gomes, R. B.; Fernandes, H.; Silva, C.; Sarakovskis, A.; Pereira, T.; Figueiredo, J.; Carvalho, B.; Soares, A.; Duarte, P.; Varandas, C.; Lielausis, O.; Klyukin, A.; Platacis, E.; Tale, I.

    2008-04-01

    The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages in the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaust from fusion devices. Presently the most promising candidate materials are lithium and gallium. However, lithium has a short liquid state range when compared, for example, with gallium that has essentially better thermal properties and lower vapor pressure. To explore further these properties, ISTTOK tokamak is being used to test the interaction of a free flying, fully formed liquid gallium jet with the plasma. The interacting, 2.3 mm diameter, jet is generated by hydrostatic pressure and has a 2.5 m/s flow velocity. The liquid metal injector has been build to allow the positioning of the jet inside the tokamak chamber, within a 13 mm range. This paper presents the first obtained experimental results concerning the liquid gallium jet-plasma interaction. A stable jet has been obtained, which was not noticeably affected by the magnetic field transients. ISTTOK has been successfully operated with the gallium jet without degradation of the discharge or a significant plasma contamination by liquid metal. This observation is supported by spectroscopic measurements showing that gallium radiation is limited to the region around the jet. Furthermore, the power deposited on the jet has been evaluated at different radial locations and the surface temperature increase estimated.

  20. Development of A Pulse Radio-Frequency Plasma Jet

    NASA Astrophysics Data System (ADS)

    Wang, Shou-Guo; Zhao, Ling-Li; Yang, Jing-Hua

    2013-09-01

    A small pulse plasma jet was driven by new developed radio-frequency (RF) power supply of 6.78 MHz. In contrast to the conventional RF 13.56 MHz atmospheric pressure plasma jet (APPJ), the power supply was highly simplified by eliminating the matching unit of the RF power supply and using a new circuit, moreover, a pulse controller was added to the circuit to produce the pulse discharge. The plasma jet was operated in a capacitively coupled manner and exhibited low power requirement of 5 W at atmospheric pressure using argon as a carrier gas. The pulse plasma plume temperature remained at less than 45 °C for an extended period of operation without using water to cool the electrodes. Optical emission spectrum measured at a wide range of 200-1000 nm indicated various excited species which were helpful in applying the plasma jet for surface sterilization to human skin or other sensitive materials. Institude of Plasma Physics, Chinese Academy of Science, Hefei, China.

  1. A Novel Electric Thruster Based on IEC Plasma Jet Technology

    SciTech Connect

    Miley, George H.; Momota, H.; Stubbers, R.

    2004-07-01

    A novel plasma jet thruster, based on Inertial Electrostatic Confinement (IEC) technology, is described for orbit transfer operations. While electronically driven, it represents a fore summer of a future fusion powered unit. The IEC thruster employs a spherical configuration, wherein ions are generated and accelerated towards the center of a spherical vacuum chamber where a high-density central core region accelerated ions into an intense quasi-neutral ion jet. Compared to other high-power plasma thrusters, the IEC offers advantages in design simplicity and minimum propellant leakage, plus a high power-to-weight ratio. (authors)

  2. Generation of Diffuse Large Volume Plasma by an Ionization Wave from a Plasma Jet

    NASA Astrophysics Data System (ADS)

    Laroussi, Mounir; Razavi, Hamid

    2015-09-01

    Low temperature plasma jets emitted in ambient air are the product of fast ionization waves that are guided within a channel of a gas flow, such as helium. This guided ionization wave can be transmitted through a dielectric material and under some conditions can ignite a discharge behind the dielectric material. Here we present a novel way to produce large volume diffuse low pressure plasma inside a Pyrex chamber that does not have any electrodes or electrical energy directly applied to it. The diffuse plasma is ignited inside the chamber by a plasma jet located externally to the chamber and that is physically and electrically unconnected to the chamber. Instead, the plasma jet is just brought in close proximity to the external wall/surface of the chamber or to a dielectric tubing connected to the chamber. The plasma thus generated is diffuse, large volume and with physical and chemical characteristics that are different than the external plasma jet that ignited it. So by using a plasma jet we are able to ``remotely'' ignite volumetric plasma under controlled conditions. This novel method of ``remote'' generation of a low pressure, low temperature diffuse plasma can be useful for various applications including material processing and biomedicine.

  3. A new DBD-driven atmospheric pressure plasma jet source on air or nitrogen

    NASA Astrophysics Data System (ADS)

    Sosnin, Eduard A.; Panarin, Victir A.; Skakun, Victor S.; Tarasenko, Victor F.; Pechenitsin, Dmitrii S.; Kuznetsov, Vladimir S.

    2015-12-01

    The paper proposes a new atmospheric pressure plasma jet (APPJ) source for operation in air and nitrogen. The conditions for the formation of stable plasma jets 4 cm long are determined. Energy and spectral measurement data are presented.

  4. Comparison of Theory with Rotation Measurements in JET ICRH Plasmas

    SciTech Connect

    R.V. Budny; C.S. Chang; C. Giroud; R.J. Goldston; D. McCune; J. Ongena; F.W. Perkins; R.B. White; K.-D. Zastrow; and contributors to the EFDA-JET work programme

    2001-06-27

    Plasma rotation appears to improve plasma performance by increasing the E x B flow shearing rate, thus decreasing radial correlations in the microturbulence. Also, plasma rotation can increase the stability to resistive MHD modes. In the Joint European Torus (JET), toroidal rotation rates omega (subscript ''tor'') with high Mach numbers are generally measured in NBI-heated plasmas (since the neutral beams aim in the co-plasma current direction). They are considerably lower with only ICRH (and Ohmic) heating, but still surprisingly large considering that ICRH appears to inject relatively small amounts of angular momentum. Either the applied torques are larger than naively expected, or the anomalous transport of angular momentum is smaller than expected. Since ICRH is one of the main candidates for heating next-step tokamaks, and for creating burning plasmas in future tokamak reactors, this paper attempts to understand ICRH-induced plasma rotation.

  5. Capillary plasma jet: A low volume plasma source for life science applications

    SciTech Connect

    Topala, I. E-mail: tmnagat@ipc.shizuoka.ac.jp; Nagatsu, M. E-mail: tmnagat@ipc.shizuoka.ac.jp

    2015-02-02

    In this letter, we present results from multispectroscopic analysis of protein films, after exposure to a peculiar plasma source, i.e., the capillary plasma jet. This plasma source is able to generate very small pulsed plasma volumes, in kilohertz range, with characteristic dimensions smaller than 1 mm. This leads to specific microscale generation and transport of all plasma species. Plasma diagnosis was realized using general electrical and optical methods. Depending on power level and exposure duration, this miniature plasma jet can induce controllable modifications to soft matter targets. Detailed discussions on protein film oxidation and chemical etching are supported by results from absorption, X-ray photoelectron spectroscopy, and microscopy techniques. Further exploitation of principles presented here may consolidate research interests involving plasmas in biotechnologies and plasma medicine, especially in patterning technologies, modified biomolecule arrays, and local chemical functionalization.

  6. Classifier based on support vector machine for JET plasma configurationsa)

    NASA Astrophysics Data System (ADS)

    Dormido-Canto, S.; Farias, G.; Vega, J.; Dormido, R.; Sánchez, J.; Duro, N.; Vargas, H.; Murari, A.; Jet-Efda Contributors

    2008-10-01

    The last flux surface can be used to identify the plasma configuration of discharges. For automated recognition of JET configurations, a learning system based on support vector machines has been developed. Each configuration is described by 12 geometrical parameters. A multiclass system has been developed by means of the one-versus-the-rest approach. Results with eight simultaneous classes (plasma configurations) show a success rate close to 100%.

  7. On Power Measurements of Single-Electrode Low-Power Ar Plasma Jets

    NASA Astrophysics Data System (ADS)

    Prysiazhnyi, Vadym; Ricci, Alonso H. C.; Kostov, Konstantin G.

    2016-06-01

    A study of electrical properties, methodology, and precision of power measurement was made on two types of Ar plasma jets, a single-strip-electrode plasma jet and a single-rod-electrode plasma jet. The dynamics of current peaks, methods for determining discharge power, and power measurement precision (especially important for applications in plasma medicine) are discussed for each type of plasma jet. Lower error in power calculation was obtained when the plasma jet did not touch the substrate, as well as more repetitive dynamics of the current peaks. Averaging high number of periods (over 500) when calculating the power by the Lissajous figure technique led to decrease of the experimental error.

  8. Modeling of High Kinetic Energy Plasma Jets for Fusion Applications

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Galkin, S. A.; Kim, J. S.

    2006-10-01

    We used semi-analytical models for high velocity (>200 km/s) and density (>10^17 cm-3) plasma jets to describe the acceleration in coaxial electrodes geometry, the collision, and plasma liner implosion, assuming that jets have merged into a spherical or cylindrical shell. The results are compared with experimental data and are being used for guiding LSP and MACH2 codes simulation and for optimization. The simplest model which uses the adiabatic invariant for oscillator revealed the basic relation between the velocity and the parameters of the plasma accelerator. Plasma slug model was extended for including friction and mass addition by electrode erosion. A simple model of blow-by instability by using the canting angle of the plasma current was formulated. As plasma jets collision at high interfacial Mach number generates shock fronts, we analyzed their possible consequences on the merging process and liner formation. The structure of the spherical shell liner during adiabatic implosion and the effect of the shock wave generated at void closure on the confinement time were also investigated.

  9. Surface modification of polymeric materials by cold atmospheric plasma jet

    NASA Astrophysics Data System (ADS)

    Kostov, K. G.; Nishime, T. M. C.; Castro, A. H. R.; Toth, A.; Hein, L. R. O.

    2014-09-01

    In this work we report the surface modification of different engineering polymers, such as, polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) by an atmospheric pressure plasma jet (APPJ). It was operated with Ar gas using 10 kV, 37 kHz, sine wave as an excitation source. The aim of this study is to determine the optimal treatment conditions and also to compare the polymer surface modification induced by plasma jet with the one obtained by another atmospheric pressure plasma source - the dielectric barrier discharge (DBD). The samples were exposed to the plasma jet effluent using a scanning procedure, which allowed achieving a uniform surface modification. The wettability assessments of all polymers reveal that the treatment leads to reduction of more than 40° in the water contact angle (WCA). Changes in surface composition and chemical bonding were analyzed by x-ray photoelectron spectroscopy (XPS) and Fourier-Transformed Infrared spectroscopy (FTIR) that both detected incorporation of oxygen-related functional groups. Surface morphology of polymer samples was investigated by Atomic Force Microscopy (AFM) and an increase of polymer roughness after the APPJ treatment was found. The plasma-treated polymers exhibited hydrophobic recovery expressed in reduction of the O-content of the surface upon rinsing with water. This process was caused by the dissolution of low molecular weight oxidized materials (LMWOMs) formed on the surface as a result of the plasma exposure.

  10. Laboratory Plasma Source as an MHD Model for Astrophysical Jets

    NASA Technical Reports Server (NTRS)

    Mayo, Robert M.

    1997-01-01

    The significance of the work described herein lies in the demonstration of Magnetized Coaxial Plasma Gun (MCG) devices like CPS-1 to produce energetic laboratory magneto-flows with embedded magnetic fields that can be used as a simulation tool to study flow interaction dynamic of jet flows, to demonstrate the magnetic acceleration and collimation of flows with primarily toroidal fields, and study cross field transport in turbulent accreting flows. Since plasma produced in MCG devices have magnetic topology and MHD flow regime similarity to stellar and extragalactic jets, we expect that careful investigation of these flows in the laboratory will reveal fundamental physical mechanisms influencing astrophysical flows. Discussion in the next section (sec.2) focuses on recent results describing collimation, leading flow surface interaction layers, and turbulent accretion. The primary objectives for a new three year effort would involve the development and deployment of novel electrostatic, magnetic, and visible plasma diagnostic techniques to measure plasma and flow parameters of the CPS-1 device in the flow chamber downstream of the plasma source to study, (1) mass ejection, morphology, and collimation and stability of energetic outflows, (2) the effects of external magnetization on collimation and stability, (3) the interaction of such flows with background neutral gas, the generation of visible emission in such interaction, and effect of neutral clouds on jet flow dynamics, and (4) the cross magnetic field transport of turbulent accreting flows. The applicability of existing laboratory plasma facilities to the study of stellar and extragalactic plasma should be exploited to elucidate underlying physical mechanisms that cannot be ascertained though astrophysical observation, and provide baseline to a wide variety of proposed models, MHD and otherwise. The work proposed herin represents a continued effort on a novel approach in relating laboratory experiments to

  11. Observation of plasma jets in a table top plasma focus discharge

    SciTech Connect

    Pavez, Cristian; Soto, Leopoldo; Pedreros, José; Tarifeño-Saldivia, Ariel

    2015-04-15

    In the last years, medium size Z-pinch experiments operating at tens of kJ are being used to create supersonic plasma jets. Those experiments are produced with wire arrays and radial foils, and they are conducted in generators based on water-filled transmission lines. Also plasma jets have been observed in small X-pinch experiments operating at 1 kJ. In this work, observations of plasma jets produced in a table top plasma focus device by means of optical and digital interferometry are shown. The device was operated at only ∼70 J, achieving 50 kA in 150 ns. The plasma jets were observed after the pinch, in the region close and on the anode, along the axis. The electron density measured from the jets is in the range 10{sup 24}–10{sup 25 }m{sup −3}. From two consecutive plasma images separated 18 ns, the axial jet velocity was measured in the order of 4 × 10{sup 4 }m/s.

  12. Dust particles interaction with plasma jet

    SciTech Connect

    Ticos, C. M.; Jepu, I.; Lungu, C. P.; Chiru, P.; Zaroschi, V.

    2009-11-10

    The flow of plasma and particularly the flow of ions play an important role in dusty plasmas. Here we present some instances in laboratory experiments where the ion flow is essential in establishing dust dynamics in strongly or weakly coupled dust particles. The formation of ion wake potential and its effect on the dynamics of dust crystals, or the ion drag force exerted on micron size dust grains are some of the phenomena observed in the presented experiments.

  13. Plasma phenomenology in astrophysical systems: Radio-sources and jets

    SciTech Connect

    Montani, Giovanni; Petitta, Jacopo

    2014-06-15

    We review the plasma phenomenology in the astrophysical sources which show appreciable radio emissions, namely Radio-Jets from Pulsars, Microquasars, Quasars, and Radio-Active Galaxies. A description of their basic features is presented, then we discuss in some details the links between their morphology and the mechanisms that lead to the different radio-emissions, investigating especially the role played by the plasma configurations surrounding compact objects (Neutron Stars, Black Holes). For the sake of completeness, we briefly mention observational techniques and detectors, whose structure set them apart from other astrophysical instruments. The fundamental ideas concerning angular momentum transport across plasma accretion disks—together with the disk-source-jet coupling problem—are discussed, by stressing their successes and their shortcomings. An alternative scenario is then inferred, based on a parallelism between astrophysical and laboratory plasma configurations, where small-scale structures can be found. We will focus our attention on the morphology of the radio-jets, on their coupling with the accretion disks and on the possible triggering phenomena, viewed as profiles of plasma instabilities.

  14. Atmospheric cold plasma jet for plant disease treatment

    NASA Astrophysics Data System (ADS)

    Zhang, Xianhui; Liu, Dongping; Zhou, Renwu; Song, Ying; Sun, Yue; Zhang, Qi; Niu, Jinhai; Fan, Hongyu; Yang, Si-ze

    2014-01-01

    This study shows that the atmospheric cold plasma jet is capable of curing the fungus-infected plant leaves and controlling the spread of infection as an attractive tool for plant disease management. The healing effect was significantly dependent on the size of the black spots infected with fungal cells and the leaf age. The leaves with the diameter of black spots of <2 mm can completely recover from the fungus-infected state. The plasma-generated species passing through the microns-sized stomas in a leaf can weaken the function of the oil vacuoles and cell membrane of fungal cells, resulting in plasma-induced inactivation.

  15. Cold atmospheric pressure plasma jet interactions with plasmid DNA

    SciTech Connect

    O'Connell, D.; Cox, L. J.; Hyland, W. B.; McMahon, S. J.; Reuter, S.; Graham, W. G.; Gans, T.; Currell, F. J.

    2011-01-24

    The effect of a cold (<40 deg. C) radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. Gel electrophoresis was used to analyze the DNA forms post-treatment. The experimental data are fitted to a rate equation model that allows for quantitative determination of the rates of single and double strand break formation. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks.

  16. On non-equilibrium atmospheric pressure plasma jets and plasma bullet

    NASA Astrophysics Data System (ADS)

    Lu, Xinpei

    2012-10-01

    Because of the enhanced plasma chemistry, atmospheric pressure nonequilibrium plasmas (APNPs) have been widely studied for several emerging applications such as biomedical applications. For the biomedical applications, plasma jet devices, which generate plasma in open space (surrounding air) rather than in confined discharge gaps only, have lots of advantages over the traditional dielectric barrier discharge (DBD) devices. For example, it can be used for root canal disinfection, which can't be realized by the traditional plasma device. On the other hand, currently, the working gases of most of the plasma jet devices are noble gases or the mixtures of the noble gases with small amount of O2, or air. If ambient air is used as the working gas, several serious difficulties are encountered in the plasma generation process. Amongst these are high gas temperatures and disrupting instabilities. In this presentation, firstly, a brief review of the different cold plasma jets developed to date is presented. Secondly, several different plasma jet devices developed in our lab are reported. The effects of various parameters on the plasma jets are discussed. Finally, one of the most interesting phenomena of APNP-Js, the plasma bullet is discussed and its behavior is described. References: [1] X. Lu, M. Laroussi, V. Puech, Plasma Sources Sci. Technol. 21, 034005 (2012); [2] Y. Xian, X. Lu, S. Wu, P. Chu, and Y. Pan, Appl. Phys. Lett. 100, 123702 (2012); [3] X. Pei, X. Lu, J. Liu, D. Liu, Y. Yang, K. Ostrikov, P. Chu, and Y. Pan, J. Phys. D 45, 165205 (2012).

  17. Plasma jet printing for flexible substrates

    NASA Astrophysics Data System (ADS)

    Gandhiraman, Ram P.; Singh, Eric; Diaz-Cartagena, Diana C.; Nordlund, Dennis; Koehne, Jessica; Meyyappan, M.

    2016-03-01

    Recent interest in flexible electronics and wearable devices has created a demand for fast and highly repeatable printing processes suitable for device manufacturing. Robust printing technology is critical for the integration of sensors and other devices on flexible substrates such as paper and textile. An atmospheric pressure plasma-based printing process has been developed to deposit different types of nanomaterials on flexible substrates. Multiwalled carbon nanotubes were deposited on paper to demonstrate site-selective deposition as well as direct printing without any type of patterning. Plasma-printed nanotubes were compared with non-plasma-printed samples under similar gas flow and other experimental conditions and found to be denser with higher conductivity. The utility of the nanotubes on the paper substrate as a biosensor and chemical sensor was demonstrated by the detection of dopamine, a neurotransmitter, and ammonia, respectively.

  18. Plasma jet's shielding gas impact on bacterial inactivation.

    PubMed

    Jablonowski, Helena; Hänsch, Mareike A Ch; Dünnbier, Mario; Wende, Kristian; Hammer, Malte U; Weltmann, Klaus-Dieter; Reuter, Stephan; Woedtke, Thomas von

    2015-01-01

    One of the most desired aims in plasma medicine is to inactivate prokaryotic cells and leave eukaryotic cells unharmed or even stimulate proliferation to promote wound healing. The method of choice is to precisely control the plasma component composition. Here the authors investigate the inactivation of bacteria (Escherichia coli) by a plasma jet treatment. The reactive species composition created by the plasma in liquids is tuned by the use of a shielding gas device to achieve a reactive nitrogen species dominated condition or a reactive oxygen species dominated condition. A strong correlation between composition of the reactive components and the inactivation of the bacteria is observed. The authors compare the results to earlier investigations on eukaryotic cells and show that it is possible to find a plasma composition where bacterial inactivation is strongest and adverse effects on eukaryotic cells are minimized. PMID:25832438

  19. PLASIMO model of micro-plasma jet for biomedical applications

    NASA Astrophysics Data System (ADS)

    Mihailova, Diana; Sobota, Ana; Graef, Wouter; van Dijk, Jan; Hagelaar, Gerjan

    2014-10-01

    Non-equilibrium atmospheric pressure micro-plasma jets are widely studied for use in biotechnology, including treatment of human tissue. The setup under study consists of capillary powered electrode through which helium gas flows and a grounded ring electrode placed a distance of few mm in front of the capillary. The discharge is excited by sinusoidal voltage with amplitude of 2 kV and 30 KHz repetition rate. The plume emanating from the jet, or the plasma bullets, propagates through a Pyrex tube and the gas phase channel of helium into the surrounding air.aim of this work is to get insight into the plasma constituents that can affect directly or indirectly living tissue. This includes radicals (OH, NO, O,), ions and electrons, UV radiation, electrical fields. PLASIMO modelling toolkit is used to simulate the capillary plasma-jet in order to quantify the delivery of fluxes and fields to the treated tissue. Verification is made by comparing results obtained with the PLASIMO and MAGMA codes (developed at LAPLACE, Toulouse) for the same input specifications. Both models are validated by comparison with experimental observations at various operating parameters.

  20. Experiments with an rf dusty plasma and an external plasma jet

    NASA Astrophysics Data System (ADS)

    Ticoş, C. M.

    2010-12-01

    A plasma jet produced in a coaxial plasma gun was aimed at a cloud of dust particles levitated in the sheath of a radio-frequency (rf) plasma produced between two parallel-plate electrodes. A high-speed camera with a side-view on the dust cloud was used to track the dust particles. Several cases of dust motion could be observed. When the jet was parallel with the horizontal electrodes of the rf plasma the dust particles were either pushed out of the trapping region by the plasma jet or were only perturbed from their equilibrium position, oscillating with a frequency of the order of a few kHz. In the first case the trajectory of the dust particles followed the curvature of the sheath. In the second case, when the jet was fired at a small angle with the horizontal electrodes the dust particles hit the bottom electrode and ricocheted back into the sheath. Finally, another situation was observed when the jet perturbed the rf plasma and its sheath and the whole dust crystal fell to the electrode.

  1. Laser Plasma Jet Driven Microparticles for DNA/Drug Delivery

    PubMed Central

    Menezes, Viren; Mathew, Yohan; Takayama, Kazuyoshi; Kanno, Akira; Hosseini, Hamid

    2012-01-01

    This paper describes a microparticle delivery device that generates a plasma jet through laser ablation of a thin metal foil and uses the jet to accomplish particle delivery into soft living targets for transferring biological agents. Pure gold microparticles of 1 µm size were coated with a plasmid DNA, pIG121Hm, and were deposited as a thin layer on one surface of an aluminum foil. The laser (Nd:YAG, 1064 nm wavelength) ablation of the foil generated a plasma jet that carried the DNA coated particles into the living onion cells. The particles could effectively penetrate the target cells and disseminate the DNA, effecting the transfection of the cells. Generation of the plasma jet on laser ablation of the foil and its role as a carrier of microparticles was visualized using a high-speed video camera, Shimadzu HPV-1, at a frame rate of 500 kfps (2 µs interframe interval) in a shadowgraph optical set-up. The particle speed could be measured from the visualized images, which was about 770 m/s initially, increased to a magnitude of 1320 m/s, and after a quasi-steady state over a distance of 10 mm with an average magnitude of 1100 m/s, started declining, which typically is the trend of a high-speed, pulsed, compressible jet. Aluminum launch pad (for the particles) was used in the present study to make the procedure cost-effective, whereas the guided, biocompatible launch pads made of gold, silver or titanium can be used in the device during the actual clinical operations. The particle delivery device has a potential to have a miniature form and can be an effective, hand-held drug/DNA delivery device for biological applications. PMID:23226394

  2. Laser plasma jet driven microparticles for DNA/drug delivery.

    PubMed

    Menezes, Viren; Mathew, Yohan; Takayama, Kazuyoshi; Kanno, Akira; Hosseini, Hamid

    2012-01-01

    This paper describes a microparticle delivery device that generates a plasma jet through laser ablation of a thin metal foil and uses the jet to accomplish particle delivery into soft living targets for transferring biological agents. Pure gold microparticles of 1 µm size were coated with a plasmid DNA, pIG121Hm, and were deposited as a thin layer on one surface of an aluminum foil. The laser (Nd:YAG, 1064 nm wavelength) ablation of the foil generated a plasma jet that carried the DNA coated particles into the living onion cells. The particles could effectively penetrate the target cells and disseminate the DNA, effecting the transfection of the cells. Generation of the plasma jet on laser ablation of the foil and its role as a carrier of microparticles was visualized using a high-speed video camera, Shimadzu HPV-1, at a frame rate of 500 kfps (2 µs interframe interval) in a shadowgraph optical set-up. The particle speed could be measured from the visualized images, which was about 770 m/s initially, increased to a magnitude of 1320 m/s, and after a quasi-steady state over a distance of 10 mm with an average magnitude of 1100 m/s, started declining, which typically is the trend of a high-speed, pulsed, compressible jet. Aluminum launch pad (for the particles) was used in the present study to make the procedure cost-effective, whereas the guided, biocompatible launch pads made of gold, silver or titanium can be used in the device during the actual clinical operations. The particle delivery device has a potential to have a miniature form and can be an effective, hand-held drug/DNA delivery device for biological applications. PMID:23226394

  3. Plasma spheroidization of iron powders in a non-transferred DC thermal plasma jet

    SciTech Connect

    Kumar, S. Selvarajan, V

    2008-06-15

    In this paper, the results of plasma spheroidization of iron powders using a DC non-transferred plasma spray torch are presented. The morphology of the processed powders was characterized through scanning electron microscopy (SEM) and optical microscopy (OM). The percentages of spheroidized powders were calculated by the shape factors such as the Irregularity Parameter (IP) and Roundness (RN). A maximum of 83% of spheroidization can be achieved. The spheroidization results are compared with the theoretical estimation and they are found to be in good agreement. The phase composition of the spheroidized powder was analyzed by XRD. The effect of plasma jet temperature and plasma gas flow rate on spheroidization is discussed. At low plasma gas flow rates and at high plasma jet temperatures, the percentage of spheroidization is high.

  4. Ion acceleration in multi-species cathodic plasma jet

    NASA Astrophysics Data System (ADS)

    Krasov, V. I.; Paperny, V. L.

    2016-05-01

    A general expression for ion-ion coupling in a multi-species plasma jet was obtained. The expression is valid for any value of the inter-species velocity. This expression has enabled us to review a hydrodynamic problem of expanding the cathodic plasma microjet with two ion species within the respective charge states Z1 = +1 and Z2 = +2 into a vacuum. We were able to illustrate that in scenario when the initial (i.e., acquired during a process of emission from cathode's surface) difference for ion's species velocity exceeds a threshold value, the difference remains noticeable (roughly about 10% of the average jet's velocity) at a distance of a few centimeters from the emission center. At this point, it can be measured experimentally.

  5. Rotating plasma jets in the photospheric intergranular lanes

    NASA Astrophysics Data System (ADS)

    Lemmerer, Birgit; Hanslmeier, Arnold; Muthsam, Herbert; Piantschitsch, Isabell; Zaqarashvili, Teimuraz

    2016-07-01

    High resolution simulations and observations of the solar photosphere reveal the population of small granular cells with diameters less than 600 km. However, the underlying mechanisms of their generation are still unclear. Simulations show that the majority of small granules may not result from fragmentation of larger granular cells but instead evolve and dissolve in the intergranular lanes. We study the dynamics of these granular cells in high resolution simulations. We found that the small granules show a jet-like behavior with strong horizontal and vertical vortex motions. A newly developed algorithm that tracks the evolution of the 3D plasma cells in the convection zone and lower photosphere shows strong vertical vorticity within the small granular cells. The rotating plasma jets, which are visible as small granules, may generate magnetized vortex flows and torsional Alfvén waves observed at upper layers and hence can play a distinct role in the energy supply to the chromosphere and corona.

  6. New X-Ray Detector for Caltech Plasma Jet Experiment

    NASA Astrophysics Data System (ADS)

    Marshall, Ryan; Bellan, Paul

    2015-11-01

    Magnetic reconnection is a process that occurs in plasmas where magnetic field lines break and re-attach to form a different topology having lower energy. Since the magnetic field is changing very fast in the reconnection region, Faraday's Law states that there is a large electric field that accelerates electrons which can then create x-rays. X-rays have been previously observed in the Caltech plasma jet experiment and in similar experiments. We have assembled a new detector consisting of a scintillator that is more than 10 times the volume of the previous one and a light guide that allows the photomultiplier tube to be 2 meters from the experiment so that electrical noise is reduced. The setup has been tested using a weak natural Thorium source and will soon be mounted on the Caltech jet experiment in front of a kapton vacuum window that allows x-rays to pass. Kapton has good transmission above 5 KeV.

  7. Etching of photoresist with an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    West, Andrew; van der Schans, Marc; Xu, Cigang; Gans, Timo; Cooke, Mike; Wagenaars, Erik

    2014-10-01

    Low-pressure oxygen plasmas are commonly used in semiconductor industry for removing photoresist from the surface of processed wafers; a process known as plasma ashing or plasma stripping. The possible use of atmospheric-pressure plasmas instead of low-pressure ones for plasma ashing is attractive from the point of view of reduction in equipment costs and processing time. We present investigations of photoresist etching with an atmospheric-pressure plasma jet (APPJ) in helium gas with oxygen admixtures driven by radio-frequency power. In these experiments, the neutral, radical rich effluent of the APPJ is used for etching, avoiding direct contact between the active plasma and the sensitive wafer, while maintaining a high etch rate. Photoresist etch rates and etch quality are measured for a range of plasma operating parameters such as power input, driving frequency, flow rate and wafer temperature. Etch rates of up to 10 micron/min were achieved with modest input power (45 W) and gas flow rate (10 slm). Fourier Transform Infrared (FTIR) spectroscopy showed that the quality of the photoresist removal was comparable to traditional plasma ashing techniques. This work was supported by the UK Engineering and Physical Sciences Research Council Grant EP/K018388/1.

  8. Coupling of axial plasma jets to compressional Alfven waves

    NASA Astrophysics Data System (ADS)

    Vincena, Stephen; Gekelman, Walter

    2009-11-01

    The coupling of mass, energy, and momentum from a localized, dense, and rapidly expanding plasma into a large-scale magnetized background plasma is central to understanding many physical processes; these include galactic jets, coronal mass ejections, tokamak pellet fueling, high-altitude nuclear detonations, chemical releases in the ionosphere, and supernovae. The large-scale magnetized plasmas are capable of supporting Alfv'en waves, which mediate the flow of currents and associated changes of magnetic topology on the largest size scales of the external system. We present initial results from a laboratory experiment wherein a fast-moving, laser-produced plasma (LPP) is allowed to propagate along the magnetic field lines of a pre-existing plasma column (17m long by 60 cm diameter). The LPP is generated using a 1J, 8ns Nd:YAG laser fired at a graphite target. The laser is pulsed along with the background plasma at 1Hz. This work focuses on the coupling of the LPP to compressional Alfv'en waves in the background plasma. The experiments are conducted at UCLA's Basic Plasma Science Facility in the Large Plasma Device.

  9. Beryllium migration in JET ITER-like wall plasmas

    NASA Astrophysics Data System (ADS)

    Brezinsek, S.; Widdowson, A.; Mayer, M.; Philipps, V.; Baron-Wiechec, P.; Coenen, J. W.; Heinola, K.; Huber, A.; Likonen, J.; Petersson, P.; Rubel, M.; Stamp, M. F.; Borodin, D.; Coad, J. P.; Carrasco, A. G.; Kirschner, A.; Krat, S.; Krieger, K.; Lipschultz, B.; Linsmeier, Ch.; Matthews, G. F.; Schmid, K.; contributors, JET

    2015-06-01

    JET is used as a test bed for ITER, to investigate beryllium migration which connects the lifetime of first-wall components under erosion with tokamak safety, in relation to long-term fuel retention. The (i) limiter and the (ii) divertor configurations have been studied in JET-ILW (JET with a Be first wall and W divertor), and compared with those for the former JET-C (JET with carbon-based plasma-facing components (PFCs)). (i) For the limiter configuration, the Be gross erosion at the contact point was determined in situ by spectroscopy as between 4% (Ein = 35 eV) and more than 100%, caused by Be self-sputtering (Ein = 200 eV). Chemically assisted physical sputtering via BeD release has been identified to contribute to the effective Be sputtering yield, i.e. at Ein = 75 eV, erosion was enhanced by about 1/3 with respect to the bare physical sputtering case. An effective gross yield of 10% is on average representative for limiter plasma conditions, whereas a factor of 2 difference between the gross erosion and net erosion, determined by post-mortem analysis, was found. The primary impurity source in the limiter configuration in JET-ILW is only 25% higher (in weight) than that for the JET-C case. The main fraction of eroded Be stays within the main chamber. (ii) For the divertor configuration, neutral Be and BeD from physically and chemically assisted physical sputtering by charge exchange neutrals and residual ion flux at the recessed wall enter the plasma, ionize and are transported by scrape-off layer flows towards the inner divertor where significant net deposition takes place. The amount of Be eroded at the first wall (21 g) and the Be amount deposited in the inner divertor (28 g) are in fair agreement, though the balancing is as yet incomplete due to the limited analysis of PFCs. The primary impurity source in the JET-ILW is a factor of 5.3 less in comparison with that for JET-C, resulting in lower divertor material deposition, by more than one order of

  10. Radiative Shocks And Plasma Jets As Laboratory Astrophysics Experiments

    SciTech Connect

    Koenig, M.; Loupias, B.; Vinci, T.; Ozaki, N.; Benuzzi-Mounaix, A.; Rabec le Goahec, M.; Falize, E.; Bouquet, S.; Courtois, C.; Nazarov, W.; Aglitskiy, Y.; Faenov, A. Ya.; Pikuz, T.; Schiavi, A.

    2007-08-02

    Dedicated laboratory astrophysics experiments have been developed at LULI in the last few years. First, a high velocity (70 km/s) radiative shock has been generated in a xenon filled gas cell. We observed a clear radiative precursor, measure the shock temperature time evolution in the xenon. Results show the importance of 2D radiative losses. Second, we developed specific targets designs in order to generate high Mach number plasma jets. The two schemes tested are presented and discussed.

  11. Radiative Shocks And Plasma Jets As Laboratory Astrophysics Experiments

    NASA Astrophysics Data System (ADS)

    Koenig, M.; Loupias, B.; Vinci, T.; Ozaki, N.; Benuzzi-Mounaix, A.; Rabec Le Goahec, M.; Falize, E.; Bouquet, S.; Michaut, C.; Herpe, G.; Baroso, P.; Nazarov, W.; Aglitskiy, Y.; Faenov, A. Ya.; Pikuz, T.; Courtois, C.; Woolsey, N. C.; Gregory, C. D.; Howe, J.; Schiavi, A.; Atzeni, S.

    2007-08-01

    Dedicated laboratory astrophysics experiments have been developed at LULI in the last few years. First, a high velocity (70 km/s) radiative shock has been generated in a xenon filled gas cell. We observed a clear radiative precursor, measure the shock temperature time evolution in the xenon. Results show the importance of 2D radiative losses. Second, we developed specific targets designs in order to generate high Mach number plasma jets. The two schemes tested are presented and discussed.

  12. Multiple (eight) plasma bullets in helium atmospheric pressure plasma jet and the role of nitrogen

    NASA Astrophysics Data System (ADS)

    Park, Sanghoo; Youn Moon, Se; Choe, Wonho

    2013-11-01

    As many as eight multiple plasma bullets produced at atmospheric pressure were observed in one voltage period in a capillary helium dielectric barrier plasma jet. We found that the number of the bullets strongly depends on the nitrogen fraction added to the helium supply gas. Using optical emission spectroscopy and ionization rate calculation, this study demonstrates that nitrogen gas plays an important role in the generation and dynamics of multiple plasma bullets through Penning ionization of nitrogen by helium metastables.

  13. Tendency of spherically imploding plasma liners formed by merging plasma jets to evolve toward spherical symmetry

    SciTech Connect

    Cassibry, J. T.; Stanic, M.; Hsu, S. C.; Witherspoon, F. D.; Abarzhi, S. I.

    2012-05-15

    We have performed three-dimensional (3D) simulations using smoothed particle hydrodynamics (SPH) in order to study the effects of discrete plasma jets on the processes of plasma liner formation, implosion on vacuum, and expansion. It was found that the pressure histories of the inner portion of the liner from 3D SPH simulations with a uniform liner and with 30 discrete plasma jets were qualitatively and quantitatively similar from peak compression through the complete stagnation of the liner. The 3D simulations with a uniform liner were first benchmarked against results from one-dimensional radiation-hydrodynamic simulations [T. J. Awe et al., Phys. Plasmas 18, 072705 (2011)]. Two-dimensional plots of the pressure field show that the discrete jet SPH case evolves towards a profile that is almost indistinguishable from the SPH case with a uniform liner, thus indicating that non-uniformities due to discrete jets are smeared out by late stages of the implosion. The processes of plasma liner formation and implosion on vacuum were shown to be robust against Rayleigh-Taylor instability growth. Finally, interparticle mixing for a liner imploding on vacuum was investigated. The mixing rate was found to be very small until after the peak compression for the 30 jet simulations.

  14. Fast Wave Current Drive in JET ITB-Plasma

    SciTech Connect

    Hellsten, T.; Laxaaback, M.; Bergkvist, T.; Johnson, T.; Brzozowski, J.; Rachlew, E.; Tennfors, E.; Mantsinen, M.; Matthews, G.; Tala, T.; Meo, F.; Nguyen, F.; Eriksson, L.-G.; Joffrin, E.; Noterdaeme, J.-M.; Petty, C.C.; Eester, D. van

    2005-09-26

    Fast wave current drive has been performed in JET plasmas with internal transport barriers, ITBs, and strongly reversed magnetic shear. Although the current drive efficiency of the power absorbed on the electrons is fairly high, only small effects are seen in the central current density. The main reasons are the parasitic absorption of RF power, the strongly inductive nature of the plasma and the interplay between the fast wave driven current and bootstrap current. The direct electron heating in the FWCD experiments is found to be strongly degraded compared to that with the dipole phasing.

  15. Functionalization of carbon nanowalls by plasma jet in liquid treatment

    NASA Astrophysics Data System (ADS)

    Ionita, Maria D.; Vizireanu, Sorin; Stoica, Silviu D.; Ionita, Mariana; Pandele, Andreea M.; Cucu, Ana; Stamatin, Ioan; Nistor, Leona C.; Dinescu, Gheorghe

    2016-02-01

    Submerged in liquid plasma treatment is a new approach for nanomaterials functionalization. This paper presents a surfactant free method for functionalization of graphene nano-platelets derived from carbon nanowalls through plasma jet treatment of their water suspensions. The untreated and under-liquid plasma treated suspensions were characterized in terms of their UV-Vis absorption, zeta-size, zeta-potential, pH, and conductivity. Investigation of dried material revealed that the graphene nano-sheets morphology and structure have been preserved, showing also new oxygen functional groups bonded to the carbon network after in liquid plasma treatment. The results demonstrate the efficiency of this technique in changing the properties of carbon nanowalls suspensions and also in getting functionalized multilayered graphene sheets.

  16. Thomson scattering measurement of a collimated plasma jet generated by a high-power laser system

    NASA Astrophysics Data System (ADS)

    Ishikawa, T.; Sakawa, Y.; Morita, T.; Yamaura, Y.; Kuramitsu, Y.; Moritaka, T.; Sano, T.; Shimoda, R.; Tomita, K.; Uchino, K.; Matsukiyo, S.; Mizuta, A.; Ohnishi, N.; Crowston, R.; Woolsey, N.; Doyle, H.; Gregori, G.; Koenig, M.; Michaut, C.; Pelka, A.; Yuan, D.; Li, Y.; Zhang, K.; Zhong, J.; Wang, F.; Takabe, H.

    2016-03-01

    One of the important and interesting problems in astrophysics and plasma physics is collimation of plasma jets. The collimation mechanism, which causes a plasma flow to propagate a long distance, has not been understood in detail. We have been investigating a model experiment to simulate astrophysical plasma jets with an external magnetic field [Nishio et al., EPJ. Web of Conferences 59, 15005 (2013)]. The experiment was performed by using Gekko XII HIPER laser system at Institute of Laser Engineering, Osaka University. We shot CH plane targets (3 mm × 3 mm × 10 μm) and observed rear-side plasma flows. A collimated plasma flow or plasma jet was generated by separating focal spots of laser beams. In this report, we measured plasma jet structure without an external magnetic field with shadowgraphy, and simultaneously measured the local parameters of the plasma jet, i.e., electron density, electron and ion temperatures, charge state, and drift velocity, with collective Thomson scattering.

  17. Study on Surface Modification of Polymer Films by Using Atmospheric Plasma Jet Source

    NASA Astrophysics Data System (ADS)

    Takemura, Yuichiro; Yamaguchi, Naohiro; Hara, Tamio

    2008-07-01

    Reactive gas plasma treatments of poly(ethylene terephthalate) (PET) and polyimide (Kapton) have been performed using an atmospheric plasmas jet source. Characteristics of surface modification have been examined by changing the distance between the plasma jet source and the treated sample, and by changing the working gas spaces. Simultaneously, each plasma jet source has been investigated by space-resolving spectroscopy in the UV/visible region. Polymer surfaces have been analyzed by X-ray photoelectron spectroscopy (XPS). A marked improvement in the hydrophilicity of the polymer surfaces has been made by using N2 or O2 plasma jet source with a very short exposure time of about 0.01 s, whereas the less improvement has been obtained using on air plasma jet source because of NOx compound production. Changes in the chemical states of C of the polymer surfaces have been observed in XPS spectra after N2 plasma jet spraying.

  18. Diagnostics of thermal spraying plasma jets

    SciTech Connect

    Fauchais, P.; Coudert, J.F.; Vardelle, M.; Vardelle, A.; Denoirjean, A. )

    1992-06-01

    The development of diagnostic techniques for dc plasma spraying is reviewed with attention given to the need for thick highly reproducible coatings of good quality for aeronautic and other uses. Among the techniques examined are fast cameras, laser-Doppler anemometry (LDA), coherent anti-Stokes Raman spectroscopy (CARS), enthalpy probes, and emission spectroscopy. Particular emphasis is given to the effect of arc fluctuations on the spectroscopic measurements, and a method is introduced for obtaining temperature and species density of vapor clouds traveling with each particle in flight. Coating properties can be deduced from data on single particles, and statistical approaches are often unreliable without added data on surface temperature and particle velocity. Also presented is a method for deriving the temperature evolution of a cooled splat and successive layers and passes. These methods are of interest to the control of adhesion and cohesion in coatings for critical aerospace applications. 70 refs.

  19. Diagnostics of thermal spraying plasma jets

    NASA Astrophysics Data System (ADS)

    Fauchais, P.; Coudert, J. F.; Vardelle, M.; Vardelle, A.; Denoirjean, A.

    1992-06-01

    The development of diagnostic techniques for dc plasma spraying is reviewed with attention given to the need for thick highly reproducible coatings of good quality for aeronautic and other uses. Among the techniques examined are fast cameras, laser-Doppler anemometry (LDA), coherent anti-Stokes Raman spectroscopy (CARS), enthalpy probes, and emission spectroscopy. Particular emphasis is given to the effect of arc fluctuations on the spectroscopic measurements, and a method is introduced for obtaining temperature and species density of vapor clouds traveling with each particle in flight. Coating properties can be deduced from data on single particles, and statistical approaches are often unreliable without added data on surface temperature and particle velocity. Also presented is a method for deriving the temperature evolution of a cooled splat and successive layers and passes. These methods are of interest to the control of adhesion and cohesion in coatings for critical aerospace applications.

  20. Polarization electric field in subalfvenic plasma jet under condition of field- aligned currents generation

    NASA Astrophysics Data System (ADS)

    Sobyanin, D.; Gavrilov, B.; Podgorny, I.

    The subalfvenic magnetized plasma jet propagating across the geomagnetic field generates field-aligned currents in the ionospheric plasma. As a result the transverse polarization electric field Ep =-VxB/c in the jet should be reduced (plasma jet depolarization). These phenomena are investigated in the laboratory experiment. It was revealed that the depolarization is accompanied by the appearing of the electric field E along the plasma velocity vector. The value of E is comparable with theaa transverse electric field. It results in the plasma jet deflection. The possibility of manifestation of these effects in the NORTH STAR Russian-American active rocket experiment is discussed.

  1. Laboratory Studies of Magnetically Driven, Radiatively Cooled Supersonic Plasma Jets

    NASA Astrophysics Data System (ADS)

    Lebedev, Sergey V.

    2010-05-01

    Results of the recent experiments with radiatively cooled jets performed on the pulsed power MAGPIE facility (1.5MA, 250ns) at Imperial College will be presented. The experiments are scalable to astrophysical flows in that critical dimensionless numbers such as the plasma collisionality, the plasma beta, Reynolds number and the magnetic Reynolds number are all in the astrophysically appropriate ranges. The experimental results will be compared with computer simulations performed with laboratory plasma codes and with astrophysical codes. The main part of the presentation will concentrate on the dynamics of magnetically driven jets, in particular on formation of episodic outflows [1]. The experimental results show the periodic ejections of magnetic bubbles naturally evolving into a heterogeneous jet propagating inside a channel made of self-collimated magnetic cavities. Experimental data on the energy balance in the magnetically driven jets, the conversion of the Poynting flux energy into kinetic energy of the outflow, will be also presented. *) In collaboration with A. CIARDI, F.A. SUZUKI-VIDAL, S.N. BLAND, M. BOCCHI, G. BURDIAK, J.P. CHITTENDEN, P. de GROUCHY, G. HALL, A. HARVEY-THOMSON, A. MAROCCHINO, G. SWADLING, A. FRANK, E. G. BLACKMAN, C. STEHLE, M. CAMENZIND. This research was sponsored by EPSRC, by the OFES DOE, by the NNSA under DOE Cooperative Agreement No. DE-FC03-02NA00057 and by the European Community's Marie Curie Actions within the JETSET network under Contract No. MRTNCT- 2004 005592. References [1] A. Ciardi, S.V. Lebedev, A. Frank et al., The Astrophysical Journal, 691: L147-L150 (2009).

  2. Adiabatic cooling of the artificial Porcupine plasma jet

    NASA Astrophysics Data System (ADS)

    Ruizhin, Iu. Ia.; Treumann, R. A.; Bauer, O. H.; Moskalenko, A. M.

    1987-01-01

    Measurements of the plasma density obtained during the interaction of the artificial plasma jet, fired into the ionosphere with the body of the Porcupine main payload, have been analyzed for times when there was a well-developed wake effect. Using wake theory, the maximum temperature of the quasi-neutral xenon ion beam has been determined for an intermediate distance from the ion beam source when the beam has left the diamagnetic region but is still much denser than the ionospheric background plasma. The beam temperature is found to be about 4 times less than the temperature at injection. This observation is very well explained by adiabatic cooling of the beam during its initial diamagnetic and current-buildup phases at distances r smaller than 10 m. Outside this region, the beam conserves the temperature achieved. The observation proves that the artificial plasma jet passes through an initial gas-like diamagnetic phase restricted to the vicinity of the beam source, where it expands adiabatically. Partial cooling also takes place outside the diamagnetic region where the beam current still builds up. The observations also support a recently developed current-closure model of the quasi-neutral ion beam.

  3. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    NASA Astrophysics Data System (ADS)

    Norberg, Seth A.; Johnsen, Eric; Kushner, Mark J.

    2015-07-01

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O2 = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  4. Jet Diffusion Flame Stabilization via Pulsed Plasma Forcing

    NASA Astrophysics Data System (ADS)

    Mungal, Godfrey

    2008-10-01

    In this work we investigate the use of high repetition rate pulsed plasma sources as a means to enhance the stability of jet diffusion flames for application to practical combustion devices. Such plasma sources have recently become popular owing to their low power requirements and their proven abilities to ignite leaner mixtures and hold stable flames. They are known to create a radical pool which can enhance combustion chemistry and thus provide increased flame stability. By first investigating a fully premixed methane/air environment we show that the resulting radical species quickly decay but leave behind a set of stable chemical species. Thus, the plasma source appears to act as a fuel reformer leading to the formation of a ``cool flame'' -- a trailing zone of weak oxidation consisting of a slightly elevated temperature stream of products containing small amounts of hydrogen and carbon monoxide. These two key species are then directly responsible for the enhanced flame behaviors. Flame stability enhancements are shown for methane jets in co-flow and cross-flow in room temperature air, and in elevated temperature vitiated air environments. Elevated ambient temperatures deplete the hydrogen and carbon monoxide due to enhanced oxidation, so while there is an enhancement to flame stability, the beneficial effects diminish with increasing temperatures in a non-linear fashion, and ultimately, provide very limited benefits at ˜1000K ambient temperature for the present studies. The conclusions here are supported by simple plasma and chemical kinetic modeling and spectroscopic and chemiluminescence measurements.

  5. Pulsed power produced counter-propagating supersonic plasma jets

    NASA Astrophysics Data System (ADS)

    Krauland, Christine; Valenzuela, J.; Collins, G.; Mariscal, D.; Narkis, J.; Krasheninnikov, I.; Haque, S.; Hammel, B.; Wallace, M.; Covington, A.; Beg, F.

    2015-11-01

    High-Mach-number, ionized, flowing gases are ubiquitous in the universe, and in many astrophysical environments they take the shape of highly collimated and unidirectional jets. Pulsed power current drivers provide the opportunity to create plasma jets while achieving conditions required to explore radiative cooling, magnetic field advection, shock formation and microinstabilities, all of which are important in the astrophysical environment. We present results from an experimental campaign carried out with the ZEBRA driver (long pulse mode: 0.5 MA in 200 ns current rise) at the Nevada Terawatt Facility where we have performed a comprehensive study of the physics of conical wire array outflows. We have implemented a double conical array configuration in which two counter-propagating jets are produced. Characterization of the jets was done with Faraday rotation, interferometry and an optical streak camera. We will present available data comparing two wire materials (Al and Cu) and the shock formation in different parameter regimes. The work is funded by the Department of Energy Grant No. DE-SC0001063 and DE-NA0001995.

  6. Ion energy distribution functions in a supersonic plasma jet

    NASA Astrophysics Data System (ADS)

    Caldirola, S.; Roman, H. E.; Riccardi, C.

    2014-11-01

    Starting from experimental measurements of ion energy distribution functions (IEDFs) in a low pressure supersonic plasma jet, we propose a model to simulate them numerically from first principles calculations. Experimentally we acquired IEDFs with a quadrupole mass spectrometer (QMS) collecting the argon ions produced from a inductively coupled plasma (ICP) and driven into a supersonic free gas expansion. From the discussion of these results and the physics of our system we developed a simulation code. Integrating the equations of motion the code evolves the trajectory of a single ion across the jet. Ar+- Ar collisions are modelled with a 12-4 Lennard-Jones potential which considers induced dipole interactions. IEDFs were simulated at different positions along the jet and compared with the experimental data showing good agreement. We have also implemented a charge transfer mechanism in which the ion releases its charge to a neutral atom which can take place at sufficiently close distances and is a function of the impact energy.

  7. Investigation on Plasma Jet Flow Phenomena During DC Air Arc Motion in Bridge-Type Contacts

    NASA Astrophysics Data System (ADS)

    Zhai, Guofu; Bo, Kai; Chen, Mo; Zhou, Xue; Qiao, Xinlei

    2016-05-01

    Arc plasma jet flow in the air was investigated under a bridge-type contacts in a DC 270 V resistive circuit. We characterized the arc plasma jet flow appearance at different currents by using high-speed photography, and two polished contacts were used to search for the relationship between roughness and plasma jet flow. Then, to make the nature of arc plasma jet flow phenomena clear, a simplified model based on magnetohydrodynamic (MHD) theory was established and calculated. The simulated DC arc plasma was presented with the temperature distribution and the current density distribution. Furthermore, the calculated arc flow velocity field showed that the circular vortex was an embodiment of the arc plasma jet flow progress. The combined action of volume force and contact surface was the main reason of the arc jet flow. supported by National Natural Science Foundation of China (Nos. 51307030, 51277038)

  8. Flute growth rate of plasma jet in mirror machine

    NASA Astrophysics Data System (ADS)

    Be'ery, I.; Seemann, O.; Goldstein, G.; Fisher, A.; Ron, A.

    2014-02-01

    The evolution of flute instability in a cold, high-density hydrogen plasma jet, injected into a mirror machine, is studied. The experiment was designed to minimize the interaction of the plasma with the walls, thus bringing it close to the ideal magnetic Rayleigh-Taylor instability conditions. The modal growth rate was measured in various settings to demonstrate the effects of the finite Larmor radius, Bohm diffusion, conductive limiter, biased limiter and neutral background gas. In this paper we will demonstrate that lowering the magnetic field increases stability, as does the insertion of a conducting ring. However, if the ring is biased, the stability is reduced due to inhomogeneous coupling between the plasma and the limiter. It was also found that heavy background gas dramatically reduces the flute instability growth rate.

  9. Electric probe investigations of microwave generated, atmospheric pressure, plasma jets

    SciTech Connect

    Porteanu, H. E.; Kuehn, S.; Gesche, R.

    2010-07-15

    We examine the applicability of the Langmuir-type of characterization for atmospheric pressure plasma jets generated in a millimeter-size cavity microwave resonator at 2.45 GHz. Wide range I-V characteristics of helium, argon, nitrogen, air and oxygen are presented for different gas fluxes, distances probe-resonator, and microwave powers. A detailed analysis is performed for the fine variation in the current around the floating potential. A simplified theory specially developed for this case is presented, considering the ionic and electronic saturation currents and the floating potential. Based on this theory, we conclude that, while the charge carrier density depends on gas flow, distance to plasma source, and microwave absorbed power, the electron temperature is quite independent of these parameters. The resulting plasma parameters for helium, argon, and nitrogen are presented.

  10. Plasmid DNA damage induced by helium atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Han, Xu; Cantrell, William A.; Escobar, Erika E.; Ptasinska, Sylwia

    2014-03-01

    A helium atmospheric pressure plasma jet (APPJ) is applied to induce damage to aqueous plasmid DNA. The resulting fractions of the DNA conformers, which indicate intact molecules or DNA with single- or double-strand breaks, are determined using agarose gel electrophoresis. The DNA strand breaks increase with a decrease in the distance between the APPJ and DNA samples under two working conditions of the plasma source with different parameters of applied electric pulses. The damage level induced in the plasmid DNA is also enhanced with increased plasma irradiation time. The reactive species generated in the APPJ are characterized by optical emission spectra, and their roles in possible DNA damage processes occurring in an aqueous environment are also discussed.

  11. Thomson scattering diagnostics of atmospheric pressure plasmas - Pulsed filament discharges and plasma jets

    NASA Astrophysics Data System (ADS)

    Tomita, Kentaro

    2015-09-01

    Recently, non-thermal atmospheric-pressure plasmas have received much attention. Because the characteristics of the plasmas are governed by free electrons, measurements of the electron density (ne) and electron temperature (Te) are a prerequisite for understanding plasma behavior. To contribute to the understanding of non-thermal atmospheric-pressure plasmas, we have been developing a laser Thomson scattering (LTS) technique as a diagnostic method for measuring ne and Te of two types of plasmas; a pulsed-filament discharge and He flow plasma jet. The pulsed filament discharge has a short current width (a few tens of ns) and a small size. In order to apply LTS to such plasmas, reproducibility of time and space of the plasmas were improved using a high-speed semiconductor switch. Spatiotemporal evolutions of ne and Te of a main discharge have been obtained. Now we try to apply LTS at a time of primary streamer. Regarding to the He flow plasma jet, the discharge was generated with He gas flow with N2/O2(20%) or N2 shielding gas. It was confirmed that the ne at the center of the plasma with N2/O2 shielding gas was around 50% higher than that with the N2 shielding gas. In collaboration with Keiichiro Urabe, The University of Tokyo; Naoki Shirai, Tokyo Metropolitan University; Safwat Hassaballa, Al-Azhar University; Nima Bolouki, Munehiro Yoneda, Takahiro Shimizu, Yuta Sato, and Kiichiro Uchino, Kyushu University.

  12. The effect of jet and DBD plasma on NCI-78 blood cancer cells

    NASA Astrophysics Data System (ADS)

    Kaushik, Nagendra K.; Kaushik, Neha; Choi, Eun Ha

    2013-06-01

    In this study we describe the effects of a nonthermal jet and dielectric barrier discharge (DBD) plasma on the T98G brain cancer cell line. The results of this study reveal that the jet and DBD plasma inhibits NCI-78 blood cancer cells growth efficiently with the loss of metabolic viability of cells. The main goal of this study is to induce cell death in NCI-78 blood cancer cells by the toxic effect of jet and DBD plasma.

  13. Collisional current drive in two interpenetrating plasma jets

    SciTech Connect

    Ryutov, D. D.; Kugland, N. L.; Park, H.-S.; Pollaine, S. M.; Remington, B. A.; Ross, J. S.

    2011-10-15

    The magnetic field generation in two interpenetrating, weakly collisional plasma streams produced by intense lasers is considered. The generation mechanism is very similar to the neutral beam injection current drive in toroidal fusion devices, with the differences related to the absence of the initial magnetic field, short interaction time, and different geometry. Spatial and temporal characteristics of the magnetic field produced in two counterstreaming jets are evaluated; it is shown that the magnetic field of order of 1 T can be generated for modest jet parameters. Conditions under which this mechanism dominates that of the ''Biermann battery'' are discussed. Other settings where the mechanism of the collisional current drive can be important for the generation of seed magnetic fields include astrophysics and interiors of hohlraums.

  14. Cold Micro-Plasma Jets in Atmospheric Pressure Air

    NASA Astrophysics Data System (ADS)

    Mohamed, A. H.; Suddala, S.; Schoenbach, K. H.

    2003-10-01

    Direct current microhollow cathode discharges (MHCDs) have been operated in air, nitrogen and oxygen at pressures of one atmosphere. The electrodes are 250 μm thick molybdenum foils, separated by an alumina insulator of the same thickness. A cylindrical hole with a diameter in the 100 μm range is drilled through all layers. By flowing gases at high pressure through this hole, plasma jets with radial dimensions on the same order as the microhole dimensions, and with lengths of up to one centimeter are generated. The gas temperature in these jets was measured by means of a micro-thermocouple. The lowest temperatures of close to room temperature were measured when the flow changed from laminar to turbulent. The results of spectral emission and absorption studies indicate high concentrations of byproducts, such as ozone, when the discharge is operated in air or oxygen. This work is supported by the U.S Air Force Office of Scientific Research (AFOSR).

  15. On the structure of plasma liners for plasma jet induced magnetoinertial fusion

    SciTech Connect

    Kim, Hyoungkeun; Zhang, Lina; Samulyak, Roman; Parks, Paul

    2013-02-15

    The internal structure and self-collapse properties of plasma liners, formed by the merger of argon plasma jets, have been studied via 3-dimensional numerical simulations using the FronTier code. We have shown that the jets merger process is accomplished through a cascade of oblique shock waves that heat the liner and reduce its Mach number. Oblique shock waves and the adiabatic compression heating have led to the 10 times reduction of the self-collapse pressure of a 3-dimensional argon liner compared to a spherically symmetric liner with the same pressure and density profiles at the merging radius. We have also observed a factor of 10 variations of pressure and density in the leading edge of the liner along spherical surfaces close to the interaction with potential plasma targets. Such a non-uniformity of imploding plasma liners presents problems for the stability of targets during compression.

  16. Plasma jet accelerator optimization with supple membrane model

    NASA Astrophysics Data System (ADS)

    Galkin, S. A.; Bogatu, I. N.; Kim, J. S.

    2006-10-01

    High density (>=3x10^17cm-3) and high Mach number (M>10) plasma jets have important applications such as plasma rotation, refueling and disruption mitigation in tokamaks. The most deleterious blow-by instability occurs in coaxial plasma accelerators; hence electrode shape optimization is required to accelerate plasmas to ˜200 km/s [1]. A full 3D particle simulation takes a huge computational time. We have developed a membrane model to provide a good starting point and further physical insight for a full 3D optimization. Our model approximates the axisymmetrical plasma by a thin supple conducting membrane with a distributed mass, located between the electrodes, and connects them to model dynamics of the blow-by instability and to conduct the optimization. The supple membrane is allowed to slip along the conductors freely or with some friction as affected by Lorenz force, generated by magnetic field inside the chamber and current on membrane. The total mass and the density distribution represent the initial plasma. The density is redistributed adiabatically during the acceleration. An external electrical circuit with capacitance, inductance and resistivity is a part of the model. The membrane model simulation results will be compared to the 2D fluid MACH2 results and then will be used to guide a full 3D optimization by the LSP code. 1. http://hyperv.com/projects/pic/

  17. Characterisation of plasma synthetic jet actuators in quiescent flow

    NASA Astrophysics Data System (ADS)

    Zong, Haohua; Kotsonis, Marios

    2016-08-01

    An experimental characterisation study of a large-volume three-electrode plasma synthetic jet actuator (PSJA) is presented. A sequential discharge power supply system is used to activate the PSJA. Phase-locked planar particle image velocimetry (PIV) and time-resolved Schlieren imaging are used to characterise the evolution of the induced flow field in quiescent flow conditions. The effect of orifice diameter is investigated. Results indicate three distinct features of the actuator-induced flow field. These are the initial shock waves, the high speed jet and vortex rings. Two types of shock waves with varied intensities, namely a strong shock wave and a weak shock wave, are issued from the orifice shortly after the ignition of the discharge. Subsequently, the emission of a high speed jet is observed, reaching velocities up to 130 m s‑1. Pronounced oscillation of the exit velocity is caused by the periodical behaviour of capacitive discharge, which also led to the formation of vortex ring trains. Orifice diameter has no influence on the jet acceleration stage and the peak exit velocity. However, a large orifice diameter results in a rapid decline of the exit velocity and thus a short jet duration time. Vortex ring propagation velocities are measured at peak values ranging from 55 m s‑1–70 m s‑1. In the case of 3 mm orifice diameter, trajectory of the vortex ring severely deviates from the actuator axis of symmetry. The development of this asymmetry in the flow field is attributed to asymmetry in the electrode configuration.

  18. Analytic model and frequency characteristics of plasma synthetic jet actuator

    NASA Astrophysics Data System (ADS)

    Zong, Hao-hua; Wu, Yun; Li, Ying-hong; Song, Hui-min; Zhang, Zhi-bo; Jia, Min

    2015-02-01

    This paper reports a novel analytic model of a plasma synthetic jet actuator (PSJA), considering both the heat transfer effect and the inertia of the throat gas. Both the whole cycle characteristics and the repetitive working process of PSJA can be predicted with this model. The frequency characteristics of a PSJA with 87 mm3 volume and different orifice diameters are investigated based on the analytic model combined with experiments. In the repetitive working mode, the actuator works initially in the transitional stage with 20 cycles and then in the dynamic balanced stage. During the transitional stage, major performance parameters of PSJA experience stepped growth, while during the dynamic balanced stage, these parameters are characterized by periodic variation. With a constant discharge energy of 6.9 mJ, there exists a saturated frequency of 4 kHz/6 kHz for an orifice diameter of 1 mm/1.5 mm, at which the time-averaged total pressure of the pulsed jet reaches a maximum. Between 0.5 mm and 1.5 mm, a larger orifice diameter leads to a higher saturated frequency due to the reduced jet duration time. As the actuation frequency increases, both the time-averaged cavity temperature and the peak jet velocity initially increase and then remain almost unchanged at 1600 K and 280 m/s, respectively. Besides, with increasing frequency, the mechanical energy incorporated in single pulsed jet, the expelled mass per pulse, and the time-averaged density in the cavity, decline in a stair stepping way, which is caused by the intermittent decrease of refresh stage duration in one period.

  19. Exploration of Plasma Jets Approach to High Energy Density Physics. Final report

    SciTech Connect

    Chen, Chiping

    2013-08-26

    High-energy-density laboratory plasma (HEDLP) physics is an emerging, important area of research in plasma physics, nuclear physics, astrophysics, and particle acceleration. While the HEDLP regime occurs at extreme conditions which are often found naturally in space but not on the earth, it may be accessible by colliding high intensity plasmas such as high-energy-density plasma jets, plasmoids or compact toroids from plasma guns. The physics of plasma jets is investigated in the context of high energy density laboratory plasma research. This report summarizes results of theoretical and computational investigation of a plasma jet undergoing adiabatic compression and adiabatic expansion. A root-mean-squared (rms) envelope theory of plasma jets is developed. Comparison between theory and experiment is made. Good agreement between theory and experiment is found.

  20. Modeling of plasma jet production from rail and coaxial guns for imploding plasma liner formation*

    NASA Astrophysics Data System (ADS)

    Mason, R. J.; Faehl, R. J.; Kirikpatrick, R. C.; Witherspoon, D.; Cassibry, J.

    2010-11-01

    We study the generation of plasma jets for forming imploding plasma liners using an enhanced version of the ePLAS implicit/hybrid model.^1 Typically, the jets are partially ionized D or Ar gases, in initial 3-10 cm long slugs at 10^16-10^18 electron/cm^3, accelerated for microseconds along 15-30 cm rail or coaxial guns with a 1 cm inter-electrode gap and driven by magnetic fields of a few Tesla. We re-examine the B-field penetration mechanisms that can be active in such wall-connected plasmas,^2 including erosion and EMHD influences, which can subsequently impact plasma liner formation and implosion. For the background and emitted plasma components we discuss optimized PIC and fluid modeling techniques, and the use of implicit fields and hybridized electrons to speed simulation. The plasmas are relatively cold (˜3 eV), so results with fixed atomic Z are compared to those from a simple analytic EOS, and allowing radiative heat loss from the plasma. The use of PIC ions is explored to extract large mean-free-path kinetic effects. 1. R. J. Mason and C. Cranfill, IEEE Trans. Plasma Sci. PS-14, 45 (1986) 2. R. Mason, et al., Phys. Fluids B, 5, 1115 (1993). [4pt] *Research supported in part by USDOE Grant DE-SC0004207.

  1. New insights on the propagation of pulsed atmospheric plasma streams: From single jet to multi jet arrays

    SciTech Connect

    Robert, E.; Darny, T.; Dozias, S.; Iseni, S.; Pouvesle, J. M.

    2015-12-15

    Atmospheric pressure plasma propagation inside long dielectric tubes is analyzed for the first time through nonintrusive and nonperturbative time resolved bi-directional electric field (EF) measurements. This study unveils that plasma propagation occurs in a region where longitudinal EF exists ahead the ionization front position usually revealed from plasma emission with ICCD measurement. The ionization front propagation induces the sudden rise of a radial EF component. Both of these EF components have an amplitude of several kV/cm for helium or neon plasmas and are preserved almost constant along a few tens of cm inside a capillary. All these experimental measurements are in excellent agreement with previous model calculations. The key roles of the voltage pulse polarity and of the target nature on the helium flow patterns when plasma jet is emerging in ambient air are documented from Schlieren visualization. The second part of this work is then dedicated to the development of multi jet systems, using two different setups, based on a single plasma source. Plasma splitting in dielectric tubes drilled with sub millimetric orifices, but also plasma transfer across metallic tubes equipped with such orifices are reported and analyzed from ICCD imaging and time resolved EF measurements. This allows for the design and the feasibility validation of plasma jet arrays but also emphasizes the necessity to account for voltage pulse polarity, target potential status, consecutive helium flow modulation, and electrostatic influence between the produced secondary jets.

  2. New insights on the propagation of pulsed atmospheric plasma streams: From single jet to multi jet arrays

    NASA Astrophysics Data System (ADS)

    Robert, E.; Darny, T.; Dozias, S.; Iseni, S.; Pouvesle, J. M.

    2015-12-01

    Atmospheric pressure plasma propagation inside long dielectric tubes is analyzed for the first time through nonintrusive and nonperturbative time resolved bi-directional electric field (EF) measurements. This study unveils that plasma propagation occurs in a region where longitudinal EF exists ahead the ionization front position usually revealed from plasma emission with ICCD measurement. The ionization front propagation induces the sudden rise of a radial EF component. Both of these EF components have an amplitude of several kV/cm for helium or neon plasmas and are preserved almost constant along a few tens of cm inside a capillary. All these experimental measurements are in excellent agreement with previous model calculations. The key roles of the voltage pulse polarity and of the target nature on the helium flow patterns when plasma jet is emerging in ambient air are documented from Schlieren visualization. The second part of this work is then dedicated to the development of multi jet systems, using two different setups, based on a single plasma source. Plasma splitting in dielectric tubes drilled with sub millimetric orifices, but also plasma transfer across metallic tubes equipped with such orifices are reported and analyzed from ICCD imaging and time resolved EF measurements. This allows for the design and the feasibility validation of plasma jet arrays but also emphasizes the necessity to account for voltage pulse polarity, target potential status, consecutive helium flow modulation, and electrostatic influence between the produced secondary jets.

  3. Coherent Structures in a Supersonic Jet Excited by Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Gaitonde, Datta; Samimy, Mo

    2010-11-01

    Simulations are used in conjunction with experimental measurements to understand the coherent structures generated by excitation of a Mach 1.3 jet by eight localized arc filament plasma actuators uniformly distributed just upstream of the nozzle exit. Several modes are excited, including the axisymmetric (m=0), helical (m=1-3), and mixed modes (m=±1, ±2) modes. The Strouhal number for all cases is fixed at 0.3, which corresponds to the most amplified frequency. The simulations reproduce the distinct coherent structures measured in the experiment for each azimuthal mode. Detailed analysis of instantaneous, time- and phase-averaged quantities highlights a complex coherent structure generation, evolution and dissipation process. A key feature observed is the initiation of hairpin-like structures with tips/heads in the outer region of the jet shear layer and legs extending forward and slightly inclined in the direction of the jet axis, where the velocity is higher. The subsequent interactions of these structures yield different composite structures in the downstream region. For example, for m=0, adjacent hairpin structures merge to yield axisymmetric rings, with the legs connecting successive structures in the form of ribs in the braid region; and with m=1 and 2 mode excitation, distinct helical and double-helical structures are observed, respectively, with the hairpins forming substructures in the coils.

  4. Influence of the Laminar Plasma Torch Construction on the Jet Characteristics

    NASA Astrophysics Data System (ADS)

    Cao, Xiuquan; Yu, Deping; Xiang, Yong; Yao, Jin; Miao, Jianguo

    2016-07-01

    Based on two typical laminar plasma torches (LPT), i.e. a multi-electrode plasma torch (MEPT) with segmented anode structure and a two-electrode plasma torch (TEPT) with conventional structure, this paper studied the influence of the LPTs construction on the jet characteristics. Experiments were designed to measure their arc voltage, jet length, thermal efficiency and specific enthalpy using a home-made data acquisition system. With them, the jet characteristics of the two different LPTs were compared in detail. Results show that different plasma torch construction leads to distinctively different characteristics of the generated plasma jet. Based on the different jet characteristics, a plasma torch with appropriate construction could be used to meet the different application requirements. supported by National Natural Science Foundation of China (No. 51405315) and the Laboratory of Precision Manufacturing Technology, CAEP (No. KF15002)

  5. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    SciTech Connect

    Norberg, Seth A. Johnsen, Eric; Kushner, Mark J.

    2015-07-07

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O{sub 2} = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  6. Influence of a plasma jet on different types of tungsten

    NASA Astrophysics Data System (ADS)

    Ankudinov, A. V.; Voronin, A. V.; Gusev, V. K.; Gerasimenko, Ya. A.; Demina, E. V.; Prusakova, M. D.; Sud'enkov, Yu. V.

    2014-03-01

    The influence of a plasma producing nonstationary thermal loads akin to edge-localized modes in a tokamak on different types of tungsten is investigated. Tungsten is irradiated by a jet of a hydrogen plasma generated in a plasma gun. The plasma density and velocity are on the order of 1022 m-3 and 100-200 km/s, respectively, and the irradiation time is 10 μs. Two plasma flux densities, 0.70 and 0.25 MJ/m2, are used. Structural modifications in irradiated single-crystal and hot-rolled tungsten samples, as well as in V-MP and ITER_D_2EDZJ4 tungsten powders, are examined. It is found that the plasma generates a regular crack network with a period of about 1 mm on the surface of the single-crystal, hot-rolled, and V-MP powder samples, while the surface of the ITER_D_2EDZJ4 powder is more cracking-resistant. The depth of the molten layer equals 1-3 μm, and the extension of intense thermal action is 15-20 μm. The material acquires a distinct regular structure with a typical grain size of less than 1 μm. X-ray diffraction analysis shows that irradiation changes the crystal lattice parameters because of the melting and crystallization of the surface layer. The examination of the V_MP tungsten powder after cyclic irradiation by a plasma with different energy densities shows that high-energy-density irradiation causes the most significant surface damage, whereas low-energy-density irradiation generates defects that are small in size even if the number of cycles is large.

  7. Interaction of an argon plasma jet with a silicon wafer

    NASA Astrophysics Data System (ADS)

    Engelhardt, Max; Pothiraja, Ramasamy; Kartaschew, Konstantin; Bibinov, Nikita; Havenith, Martina; Awakowicz, Peter

    2016-04-01

    A filamentary discharge is ignited in an argon plasma jet under atmospheric pressure conditions. The gas discharge is characterized with voltage-current measurements, optical emission spectroscopy and an ICCD-camera with a high temporal resolution down to 10 ns. In the effluent of the plasma jet, filaments come into contact with the surface of a silicon wafer and modify it, namely etching traces are produced and microcrystals are deposited. These traces are studied with optical and electron microscopes. The material of the deposited microcrystals and the surface modifications of the silicon wafer are analyzed with Raman microspectroscopy. Amorphous silicon is found within the etching traces. The largest part of the deposited microcrystals are composed of nitratine (NaNO3) and some of them are calcite (CaCO3). Analyzing the possible reasons for the silicon wafer modifications we come to the conclusion that plasmoids, which are produced near the substrate surface by interaction with ionization waves, are a plausible explanation for the observed surface modifications of the silicon wafer.

  8. Atmospheric Pressure Plasma Jet for Chem/Bio Warfare Decontamination

    NASA Astrophysics Data System (ADS)

    Herrmann, Hans W.; Henins, Ivars; Park, Jaeyoung; Selwyn, Gary S.

    1999-11-01

    Atmospheric Pressure Plasma Jet (APPJ) technology may provide a much needed method of CBW decontamination which, unlike traditional decon methods, is dry and nondestructive to sensitive equipment and materials. The APPJ discharge uses a high-flow feedgas consisting primarily of an inert carrier gas, such as He, and a small amount of a reactive additive, such as O2, which flows between capacitively-coupled electrodes powered at 13.56 MHz. The plasma generates highly reactive metastable and atomic species of oxygen which are then directed onto a contaminated surface. The reactive effluent of the APPJ has been shown to effectively neutralize VX nerve agent as well as simulants for anthrax and mustard blister agent. Research efforts are now being directed towards reducing He consumption and increasing the allowable stand-off distance. Recent results demonstrate that by replacing the O2 reactive additive with CO2, ozone formation is greatly reduced. This has the result of extending the lifetime of atomic oxygen by an order of magnitude or more. A recirculating APP Decon Chamber which combines heat, vacuum, forced convection and reactivity is currently being developed for enhanced decontamination of sensitive equipment. Several techniques are also being evaluated for use in an APP Decon Jet for decontamination of items which cannot be placed inside a chamber.

  9. High kinetic energy plasma jet generation and its injection into the Globus-M spherical tokamak

    NASA Astrophysics Data System (ADS)

    Voronin, A. V.; Gusev, V. K.; Petrov, Yu. V.; Sakharov, N. V.; Abramova, K. B.; Sklyarova, E. M.; Tolstyakov, S. Yu.

    2005-09-01

    Progress in the theoretical and experimental development of the plasma jet source and injection of hydrogen plasma and neutral gas jets into the Globus-M spherical tokamak is discussed. An experimental test bed is described for investigation of intense plasma jets that are generated by a double-stage plasma gun consisting of an intense source for neutral gas production and a conventional pulsed coaxial accelerator. A procedure for optimizing the accelerator parameters so as to achieve the maximum possible flow velocity with a limited discharge current and a reasonable length of the coaxial electrodes is presented. The calculations are compared with experiment. Plasma jet parameters, among them pressure distribution across the jet, flow velocity, plasma density, etc, were measured. Plasma jets with densities of up to 1022 m-3, total numbers of accelerated particles (1-5) × 1019, and flow velocities of 50-100 km s-1 were successfully injected into the plasma column of the Globus-M tokamak. Interferometric and Thomson scattering measurements confirmed deep jet penetration and a fast density rise (<0.5 ms) at all spatial points up to a radius rap 0.3a. The plasma particle inventory increase by ~50% (from 0.65 × 1019 to 1 × 1019) did not result in plasma degradation.

  10. Tantalum Etching with an Atmospheric Pressure Plasma Jet

    NASA Astrophysics Data System (ADS)

    Teslow, Hilary; Herrmann, Hans; Rosocha, Louis

    2002-10-01

    The APPJ is a non-thermal, atmospheric-pressure, glow discharge. A feedgas, composed of an inert carrier gas (e.g., He) and small concentrations of additives (e.g., O2, or CF4), flows between closely spaced electrodes powered at 13.56 MHz rf in a coaxial or parallel plate arrangement. The plasma has Te ˜ 2 eV and ne ˜ 10^11 cm-3. Electrons are not in thermal equilibrium with ions and neutrals: the electrons are ``hot", while the overall gas temperature is quite ``cold", typically 50-300 C. In the plasma, the gas is excited, dissociated or ionized by energetic electron impact. As the gas exits the discharge volume, ions and electrons are rapidly lost by recombination, leaving metastables (e.g. O2*, He*) and radicals (e.g. O, F, OF, O2F, CFO). These reactive species are then directed onto a surface to be processed. The APPJ has been developed for decontaminating nuclear, chemical, and biological agents. Atomic fluorine, and possibly other reactive species, can be used to convert actinides (e.g., U and Pu), into volatile fluorides (e.g., UF6, PuF6) that can be trapped, resulting in significant volume reduction of radioactive waste. In this talk, we will present results on using Ta as a surrogate for Pu in He/O2/CF4 etching plasmas. Results of experimental measurements of Ta etch rates for various gas mixtures and plasma jet standoff distance will be compared with plasma chemistry modeling of the concentrations of several active species produced in the plasma.

  11. Jet energy loss in the quark-gluon plasma by stream instabilities

    SciTech Connect

    Mannarelli, Massimo; Manuel, Cristina; Gonzalez-Solis, Sergi; Strickland, Michael

    2010-04-01

    We study the evolution of the plasma instabilities induced by two jets of particles propagating in opposite directions and crossing a thermally equilibrated non-Abelian plasma. In order to simplify the analysis we assume that the two jets of partons can be described with uniform distribution functions in coordinate space and by Gaussian distribution functions in momentum space. We find that while crossing the quark-gluon plasma, the jets of particles excite unstable chromomagnetic and chromoelectric modes. These fields interact with the particles (or hard modes) of the plasma inducing the production of currents; thus, the energy lost by the jets is absorbed by both the gauge fields and the hard modes of the plasma. We compare the outcome of the numerical simulations with the analytical calculation performed assuming that the jets of particles can be described by a tsunamilike distribution function. We find qualitative and semiquantitative agreement between the results obtained with the two methods.

  12. Compact High-Velocity Atmospheric Pressure Dielectric Barrier Plasma Jet in Ambient Air

    NASA Astrophysics Data System (ADS)

    Annette, Meiners; Michael, Leck; Bernd, Abel

    2015-01-01

    In this paper, a non-thermal atmospheric pressure plasma jet at high streaming velocity operating with ambient air is highlighted. In the present technological approach, the employment of air poses a significant challenge. The high oxygen concentration in air results in a reduced concentration of reactive species in combination with a short species lifetime. The plasma jet assembly presented here contains a special dielectric barrier with a high secondary emission coefficient. In this way, the electron density and in turn the density of reactive species is increased. In addition, the plasma jet assembly is equipped with a short electrode. This leads to a higher voltage across the discharge gap and in turn to an increased density of reactive plasma species. The plasma jet is formed within and emitted by a small conical nozzle. A high-speed gas flow with gas velocity of 340 m/s was achieved at the end of the nozzle. In the jet the concentration of toxic and unwanted neutral plasma species like O3 or NOx is significantly reduced because of the shorter residence time within the plasma. The range of short-lived active plasma species is in turn considerably enhanced. The jet efficiency and action range measured through the oxidation of a test surface were determined by measuring the increase of surface tension of a polypropylene substrate via contact angle measurements after plasma treatment. Numerical modeling of the plasma plume indicates that oxygen atoms are in fact the main active species in the plasma plume.

  13. Multiple Plasma Ejections and Intermittent Nature of Magnetic Reconnection in Solar Chromospheric Anemone Jets

    NASA Astrophysics Data System (ADS)

    Singh, K. A. P.; Isobe, H.; Nishizuka, N.; Nishida, K.; Shibata, K.

    2012-11-01

    The recent discovery of chromospheric anemone jets with the Solar Optical Telescope (SOT) on board Hinode has shown an indirect evidence of magnetic reconnection in the solar chromosphere. However, the basic nature of magnetic reconnection in chromosphere is still unclear. We studied nine chromospheric anemone jets from SOT/Hinode using Ca II H filtergrams, and we found multiple bright, plasma ejections along the jets. In most cases, the major intensity enhancements (larger than 30% relative to the background intensity) of the loop correspond to the timing of the plasma ejections. The typical lifetime and size of the plasma ejecta are about 20-60 s and 0.3-1.5 Mm, respectively. The height-time plot of jet shows many sub-structures (or individual jets) and the typical lifetime of the individual jet is about one to five minutes. Before the onset of the jet activity, a loop appears in Ca II H and gradually increases in size, and after few minutes several jets are launched from the loop. Once the jet activity starts and several individual jets are launched, the loop starts shrinking with a speed of ~4 km s-1. In some events, a downward moving blob with a speed of ~35 km s-1 was observed, associated with the upward moving plasma along one of the legs of the loop hosting the jets. The upward moving plasma gradually developed into jets. Multiple plasma ejections in chromospheric anemone jet show the strongly time-dependent as well as intermittent nature of magnetic reconnection in the solar chromosphere.

  14. MULTIPLE PLASMA EJECTIONS AND INTERMITTENT NATURE OF MAGNETIC RECONNECTION IN SOLAR CHROMOSPHERIC ANEMONE JETS

    SciTech Connect

    Singh, K. A. P.; Nishida, K.; Shibata, K.; Isobe, H.; Nishizuka, N. E-mail: nishida@kwasan.kyoto-u.ac.jp E-mail: isobe@kwasan.kyoto-u.ac.jp

    2012-11-01

    The recent discovery of chromospheric anemone jets with the Solar Optical Telescope (SOT) on board Hinode has shown an indirect evidence of magnetic reconnection in the solar chromosphere. However, the basic nature of magnetic reconnection in chromosphere is still unclear. We studied nine chromospheric anemone jets from SOT/Hinode using Ca II H filtergrams, and we found multiple bright, plasma ejections along the jets. In most cases, the major intensity enhancements (larger than 30% relative to the background intensity) of the loop correspond to the timing of the plasma ejections. The typical lifetime and size of the plasma ejecta are about 20-60 s and 0.3-1.5 Mm, respectively. The height-time plot of jet shows many sub-structures (or individual jets) and the typical lifetime of the individual jet is about one to five minutes. Before the onset of the jet activity, a loop appears in Ca II H and gradually increases in size, and after few minutes several jets are launched from the loop. Once the jet activity starts and several individual jets are launched, the loop starts shrinking with a speed of {approx}4 km s{sup -1}. In some events, a downward moving blob with a speed of {approx}35 km s{sup -1} was observed, associated with the upward moving plasma along one of the legs of the loop hosting the jets. The upward moving plasma gradually developed into jets. Multiple plasma ejections in chromospheric anemone jet show the strongly time-dependent as well as intermittent nature of magnetic reconnection in the solar chromosphere.

  15. Magnetic Probe to Study Plasma Jets for Magneto-Inertial Fusion

    SciTech Connect

    Martens, Daniel; Hsu, Scott C.

    2012-08-16

    A probe has been constructed to measure the magnetic field of a plasma jet generated by a pulsed plasma rail-gun. The probe consists of two sets of three orthogonally-oriented commercial chip inductors to measure the three-dimensional magnetic field vector at two separate positions in order to give information about the magnetic field evolution within the jet. The strength and evolution of the magnetic field is one of many factors important in evaluating the use of supersonic plasma jets for forming imploding spherical plasma liners as a standoff driver for magneto-inertial fusion.

  16. Plasma jets subject to adjustable current polarities and external magnetic fields

    NASA Astrophysics Data System (ADS)

    Byvank, Tom; Schrafel, Peter; Gourdain, Pierre; Seyler, Charles; Kusse, Bruce

    2014-12-01

    In the present research, collimated plasma jets form from ablation of a radial foil (Al 20 μm thin disk) using a pulsed power generator (COBRA) with 1 MA peak current and 100 ns rise time. Plasma dynamics of the jet are diagnosed with and without an applied uniform axial magnetic field (1 T) and under a change of current polarities, which correspond to current moving either radially outward or inward from the foil's central axis. Experimental results are compared with numerical simulations (PERSEUS). The influence of the Hall effect on the jet development is observed under opposite current polarities. Additionally, the magnetic field compression within the jet is examined. Further studies will compare the laboratory-generated plasma jets and astrophysical jets with embedded magnetic fields.

  17. Plasma Jets Subject to Adjustable Current Polarities and External Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Byvank, Tom; Schrafel, Peter; Gourdain, Pierre; Seyler, Charles; Kusse, Bruce

    2014-10-01

    In the present research, collimated plasma jets form from ablation of a radial foil (Al 20 μm thin disk) using a pulsed power generator (COBRA) with 1 MA peak current and 100 ns rise time. Plasma dynamics of the jet are diagnosed with and without an applied uniform external field (1-1.5 T) and under a change of current polarities, which correspond to current moving either radially outward or inward from the foil's central axis. Experimental results are compared with numerical simulations (PERSEUS). The influence of the Hall effect on the jet development is observed under opposite current polarities. Additionally, the magnetic field compression within the jet is examined. Further studies will compare the laboratory-generated plasma jets and astrophysical jets with embedded magnetic fields.

  18. Large-scale jets in the magnetosheath and plasma penetration across the magnetopause: THEMIS observations

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. V.; Suvorova, A. V.

    2015-06-01

    Time History of Events and Macroscale Interactions during Substorms multipoint observation of the plasma and magnetic fields, conducted simultaneously in the dayside magnetosheath and magnetosphere, were used to collect 646 large-scale magnetosheath plasma jets interacting with the magnetopause. The jets were identified as dense and fast streams of the magnetosheath plasma whose energy density is higher than that of the upstream solar wind. The jet interaction with the magnetopause was revealed from sudden inward motion of the magnetopause and an enhancement in the geomagnetic field. The penetration was determined as appearance of the magnetosheath plasma against the background of the hot magnetospheric particle population. We found that almost 60% of the jets penetrated through the magnetopause. Vast majority of the penetrating jets was characterized by high velocities V > 220 km/s and kinetic βk > 1 that corresponded to a combination of finite Larmor radius effect with a mechanism of impulsive penetration. The average plasma flux in the penetrating jets was found to be 1.5 times larger than the average plasma flux of the solar wind. The average rate of jet-related penetration of the magnetosheath plasma into the dayside magnetosphere was estimated to be ~1029 particles/d. The rate varies highly with time and can achieve values of 1.5 × 1029 particles/h that is comparable with estimates of the total amount of plasma entering the dayside magnetosphere.

  19. Impact of an atmospheric argon plasma jet on a dielectric surface and desorption of organic molecules

    NASA Astrophysics Data System (ADS)

    Damany, Xavier; Pasquiers, Stéphane; Blin-Simiand, Nicole; Bauville, Gérard; Bournonville, Blandine; Fleury, Michel; Jeanney, Pascal; Santos Sousa, João

    2016-08-01

    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 (≤10 mm). Changing the angle between the capillary tube and the glass plate, and varying the gas flow rate strongly affects the spatial extension of the plasma that develops on the surface. This surface plasma propagates while the plasma in the argon jet is maintained with the same luminous intensity. Finally, this plasma jet shows interesting characteristics for desorption of low volatile organic molecules such as bibenzyl. A maximum removal of bibenzyl is located at the intersection area between the jet axis and the glass surface, and some of the initially deposited molecules are found intact in gas phase. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  20. A novel method for the detection of plasma jet boundaries by exploring DNA damage

    NASA Astrophysics Data System (ADS)

    Bahnev, Blagovest; Bowden, Mark D.; Stypczyńska, Agnieszka; Ptasińska, Sylwia; Mason, Nigel J.; Braithwaite, Nicholas St. J.

    2014-06-01

    In this study we have investigated the plasma-air boundary of an atmospheric pressure discharge by exposing samples of dry plasmid DNA to a plasma jet. While visible emission from excited plasma species suggested that the plasma jet had dimensions approximately 5.5 cm long and 0.4 cm wide, damage to DNA samples was detected at distances of up to 20 cm from the tip of the jet with observable effects far outside the luminous plasma volume. Reactive oxygen species were identified as the most likely cause of DNA damage at these long distances. These results provide a novel method for determining the extent of any kind of plasma jet generated in the open atmosphere.

  1. Characterization of linear plasma synthetic jet actuators in an initially quiescent medium

    SciTech Connect

    Santhanakrishnan, Arvind; Reasor, Daniel A. Jr.; LeBeau, Raymond P. Jr.

    2009-04-15

    The plasma synthetic jet actuator (PSJA) is a geometrical variant of the aerodynamic plasma actuator that can be used to produce zero-mass flux jets similar to those created by mechanical devices. This jet can be either three-dimensional using annular electrode arrays (annular PSJA) or nearly two dimensional using two rectangular-strip exposed electrodes and one embedded electrode (linear PSJA). Unsteady pulsing of the PSJA at time scales decoupled to the ac input frequency results in a flow field dominated by counter-rotating vortical structures similar to conventional synthetic jets, and the peak velocity and momentum of the jet is found to be affected by a combination of the pulsing frequency and input power. This paper investigates the fluid dynamic characteristics of linear plasma synthetic jet actuators in an initially quiescent medium. Two-dimensional particle image velocimetry measurements on the actuator are used to validate a previously developed numerical model wherein the plasma behavior is introduced into the Navier-Stokes equations as an electrohydrodynamic force term calculated from Maxwell's equations and solved for the fluid momentum. The numerical model was implemented in an incompressible, unstructured grid code. The results of the simulations are observed to reproduce some aspects of the qualitative and quantitative experimental behavior of the jet for steady and pulsed modes of actuator operation. The self-similarity behavior of plasma synthetic jets are examined and compared to mechanically driven continuous and synthetic jets.

  2. On the evolution of jet energy and opening angle in strongly coupled plasma

    NASA Astrophysics Data System (ADS)

    Chesler, Paul M.; Rajagopal, Krishna

    2016-05-01

    We calculate how the energy and the opening angle of jets in {N} = 4 SYM theory evolve as they propagate through the strongly coupled plasma of that theory. We define the rate of energy loss dE jet /dx and the jet opening angle in a straightforward fashion directly in the gauge theory before calculating both holographically, in the dual gravitational description. In this way, we rederive the previously known result for dE jet /dx without the need to introduce a finite slab of plasma. We obtain a striking relationship between the initial opening angle of the jet, which is to say the opening angle that it would have had if it had found itself in vacuum instead of in plasma, and the thermalization distance of the jet. Via this relationship, we show that {N} = 4 SYM jets with any initial energy that have the same initial opening angle and the same trajectory through the plasma experience the same fractional energy loss. We also provide an expansion that describes how the opening angle of the {N} = 4 SYM jets increases slowly as they lose energy, over the fraction of their lifetime when their fractional energy loss is not yet large. We close by looking ahead toward potential qualitative lessons from our results for QCD jets produced in heavy collisions and propagating through quark-gluon plasma.

  3. DEVELOPMENT OF WATER JET PLASMA MIRROR FOR STAGING OF LASER PLASMA ACCELERATORS

    SciTech Connect

    Panasenko, Dmitriy; Gonsalves, Anthony J.; Leemans, Wim; Nakamura, Kei; Shu, Anthony; Toth, Csaba

    2009-05-04

    Staging Laser Plasma Accelerators (LPAs) is necessary in order to reach beam energies of 100 GeV and above. This requires incoupling of additional laser beams into accelerating stages. In order to maintain the high average accelerating gradient of a staged LPA, it is imperative to minimize the distance that is needed for laser incoupling. A plasma mirror is proposed as the final coupling optic reducing the coupling distance from tens of meters, using a conventional optic, to as small as a few cm. Both a planar water jet and a nitrocellulose foil are used as reflecting surfacesand characterized. A maximum reflectivity of 70percent was obtained using both surfaces.

  4. Electrical studies and plasma characterization of an atmospheric pressure plasma jet operated at low frequency

    SciTech Connect

    Giuliani, L.; Xaubet, M.; Grondona, D.; Minotti, F.; Kelly, H.

    2013-06-15

    Low-temperature, high-pressure plasma jets have an extensive use in medical and biological applications. Much work has been devoted to study these applications while comparatively fewer studies appear to be directed to the discharge itself. In this work, in order to better understand the kind of electrical discharge and the plasma states existing in those devices, a study of the electrical characteristics of a typical plasma jet, operated at atmospheric pressure, using either air or argon, is reported. It is found that the experimentally determined electrical characteristics are consistent with the model of a thermal arc discharge, with a highly collisional cathode sheet. The only exception is the case of argon at the smallest electrode separation studied, around 1 mm in which case the discharge is better modeled as either a non-thermal arc or a high-pressure glow. Also, variations of the electrical behavior at different gas flow rates are interpreted, consistently with the arc model, in terms of the development of fluid turbulence in the external jet.

  5. Effects of real viscosity on plasma liner formation and implosion from supersonic plasma jets

    NASA Astrophysics Data System (ADS)

    Schillo, Kevin; Cassibry, Jason; Hsu, Scott; PLX-Alpha Team

    2015-11-01

    The PLX- α project endeavors to study plasma liner formation and implosion by merging of a spherical array of plasma jets as a candidate standoff driver for magneto-inertial fusion (MIF). Smoothed particle hydrodynamics (SPH) is being used to model the liner formation and implosion processes. SPH is a meshless Lagrangian method to simulate fluid flows by dividing a fluid into a set of particles and using a summation interpolant function to calculate the properties and gradients for each of these particles. The SPH code was used to simulate test cases in which the number of plasma guns and initial conditions for the plasma were varied. Linear stabilizations were observed, but the possibility exists that this stabilization was due to the implementation of artificial viscosity in the code. A real viscosity model was added to our SPHC model using the Braginskii ion viscosity. Preliminary results for test cases that incorporate real viscosity are presented.

  6. Production of centimeter-scale, high-density plasmas with a linear gas jet

    SciTech Connect

    Coverdale, C.A.; Darrow, C.B.; Jones, R.; Sawyer, W.; Crane, J.; Ditmire, T.; Perry, M.D. ); Filbert, P.C. )

    1995-01-01

    A novel linear gas jet has been developed and used to produce centimeter-scale, 10[sup 19] cm[sup [minus]3] electron density plasmas. Long regions of high density are important to many types of experiments, including x-ray laser and laser-plasma interaction studies. This new type of gas jet has been characterized by stimulated Raman backscatter emission from the plasma.

  7. Effect of non-thermal atmospheric pressure plasma jet on human breast cancer cells

    NASA Astrophysics Data System (ADS)

    Mirpour, Shahriar; Nikkhah, Maryam; Pirouzmand, Somaye; Ghomi, Hamid Reza

    2012-10-01

    Nowadays, Non-thermal plasma enjoy a wide range of applications in biomedical fields such as Sterilization, Wound healing, Cancer treatment and etc. The aim of this paper is to study the effect of non-thermal atmospheric pressure plasma jet on breast cancer (MCF-7) cells. In this regard the effect of plasma on death of the cancer cells are explored experimentally. The plasma in this discharge is created by pulsed dc high voltage power supply with repetition rate of several tens of kilohertz which led to the inductively coupled plasma. The pure helium gas were used for formation of the plasma jet. MTT assay were used for quantification of death cells. The results showed that the cells death rate increase with plasma exposure time. This study confirm that plasma jet have significant effect on treatment of human breast cancer cells.

  8. Modeling the Compression of Merged Compact Toroids by Multiple Plasma Jets

    NASA Astrophysics Data System (ADS)

    Thio, Y. C. Francis; Knapp, Charles E.; Kirkpatrick, Ron

    2000-10-01

    A fusion propulsion scheme has been proposed that makes use of the merging of a spherical distribution of plasma jets to dynamically form a gaseous liner. The gaseous liner is used to implode a magnetized target to produce the fusion reaction in a standoff manner. In this paper, the merging of the plasma jets to form the gaseous liner is investigated numerically. The Los Alamos SPHINX code, based on the smoothed particle hydrodynamics method is used to model the interaction of the jets. 2-D and 3-D simulations have been performed to study the characterisitcs of the resulting flow when these jets collide. The results show that the jets merge to form a plasma liner that converge radially which may be used to compress the central plasma to fusion conditions. Details of the computational model and the SPH numerical methods will be presented together with the numerical results.

  9. Modeling the Compression of Merged Compact Toroids by Multiple Plasma Jets

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Knapp, Charles E.; Kirkpatrick, Ron; Rodgers, Stephen L. (Technical Monitor)

    2000-01-01

    A fusion propulsion scheme has been proposed that makes use of the merging of a spherical distribution of plasma jets to dynamically form a gaseous liner. The gaseous liner is used to implode a magnetized target to produce the fusion reaction in a standoff manner. In this paper, the merging of the plasma jets to form the gaseous liner is investigated numerically. The Los Alamos SPHINX code, based on the smoothed particle hydrodynamics method is used to model the interaction of the jets. 2-D and 3-D simulations have been performed to study the characteristics of the resulting flow when these jets collide. The results show that the jets merge to form a plasma liner that converge radially which may be used to compress the central plasma to fusion conditions. Details of the computational model and the SPH numerical methods will be presented together with the numerical results.

  10. Etude theorique du jet de plasma supersonique a courant continu

    NASA Astrophysics Data System (ADS)

    Jodoin, Bertrand

    La déposition par plasma supersonique à courant continu permet d'obtenir une qualité de dépôt supérieure au jet subsonique. Un modèle numérique a été développé dans le but de mieux comprendre les mécanismes de transfert à l'intérieur de la tuyère et d'estimer l'influence des paramètres d'opération de la torche sur le jet à la sortie de la tuyère. Les équations d'Euler, auxquelles sont ajoutées l'effet Joule, la conduction et les pertes par rayonnement sont résolues à l'aide de la méthode de Jameson. Un schéma centré est utilisé pour résoudre les champs électriques. La sous-couche cathodique en déséquilibre thermodynamique est modélisée à l'aide du modèle simple de Morrow et Lowke. Quelques détails sur les aspects numériques facilitant la convergence du système sont donnés. Le modèle est validé pour un écoulement compressible classique et pour un jet de plasma supersonique à l'aide de résultats de la littérature. Les champs à l'intérieur de la tuyère sont analysés afin de déterminer l'influence de l'hydrogène, de l'intensité du courant et de la géométrie de la tuyère sur les caractéristiques de l'écoulement.

  11. Modelling penetration and plasma response of a dense neutral gas jet in a post-thermal quenched plasma

    NASA Astrophysics Data System (ADS)

    Parks, P. B.; Wu, W.

    2014-02-01

    This paper is about the dynamics of gas jet injection and propagation into the cold, current quench (CQ) discharge following the thermal quench (TQ) phase of a disruption event. Understanding the processes involved in the interpenetration between a dense, fast-moving supersonic gas jet and a magnetized plasma is fundamental to the solution of the disruption mitigation problem using massive gas injection. An analytical model was developed that provides the penetration depth of the jet in the CQ discharge. The model developed incorporates the injector, the vacuum space between injector and plasma, and the low beta CQ plasma through which the jet penetrates. The radially moving gas stagnates at some point inside the plasma by formation of a ‘bottle shock’, resulting in a certain penetration depth. Consistent with experimental findings, it is shown that high fuelling efficiency >70% and good penetration beyond the q = 2 surface is possible in such plasma discharges, but in normal (unquenched) plasma discharges penetration of dense gas jets will be quite poor. The paper also sheds light on how the external plasma responds to allow interpenetration of perfectly insulating gas jet through a strong magnetic field B2/2μ0 ≫ ρu2. The paper also develops semi-analytical models for the response of the cold, high-current, collision-dominated plasma to the insertion of a dense neutral jet: the propagation of cooling waves out along the magnetic field lines, the heated and ionized surface layer which also expands outwards along the magnetic field lines, and the electrical breakdown of the neutral gas within the jet volume. Although good penetration in the ITER post-TQ discharge can be achieved, the plasma resistivity is only marginally enhanced. This may render repetitive gas inject ineffective, as the concept requires a sizable resistivity enhancement to initiate a current profile contraction, and resulting kink-tearing activity to suppress runaway avalanching.

  12. Comparison of H-mode plasmas in JET-ILW and JET-C with and without nitrogen seeding

    NASA Astrophysics Data System (ADS)

    Jaervinen, A. E.; Giroud, C.; Groth, M.; Belo, P.; Brezinsek, S.; Beurskens, M.; Corrigan, G.; Devaux, S.; Drewelow, P.; Harting, D.; Huber, A.; Jachmich, S.; Lawson, K.; Lipschultz, B.; Maddison, G.; Maggi, C.; Marchetto, C.; Marsen, S.; Matthews, G. F.; Meigs, A. G.; Moulton, D.; Sieglin, B.; Stamp, M. F.; Wiesen, S.; Contributors, JET

    2016-04-01

    In high confinement mode, highly shaped plasmas with edge localized modes in JET, and for heating power of 15-17 MW, the edge fluid code EDGE2D-EIRENE predicts transition to detachment assisted by nitrogen at the low field side (LFS) target when more than 50% of the power crossing the separatrix between ELMs is radiated in the divertor chamber, i.e. ~4 MW. This is observed both in the ITER-like wall (JET-ILW) and in the carbon wall (JET-C) configurations and is consistent with experimental observations within their uncertainty. In these conditions, peak heat fluxes below 1 MW m-2 are measured at the LFS target and predicted for both wall configurations. When the JET-C configuration is replaced with the JET-ILW, a factor of two reduction in the divertor radiated power and 25-50% increase in the peak and total power deposited to the LFS divertor plate is predicted by EDGE2D-EIRENE for unseeded plasmas similar to experimental observations. At the detachment threshold, EDGE2D-EIRENE shows that nitrogen radiates more than 80% of the total divertor radiation in JET-ILW with beryllium contributing less than a few %. With JET-C, nitrogen radiates more than 70% with carbon providing less than 20% of the total radiation. Therefore, the lower intrinsic divertor radiation with JET-ILW is compensated by stronger nitrogen radiation contribution in simulations leading to detachment at similar total divertor radiation fractions. 20-100% higher deuterium molecular fraction in the divertor recycling fluxes is predicted with light JET-C materials when compared to heavy tungsten. EDGE2D-EIRENE simulations indicate that the stronger molecular contribution can reduce the divertor peak power deposition in high recycling conditions by 10-20% due to enhanced power dissipation by molecular interaction.

  13. Cold atmospheric air plasma jet for medical applications

    NASA Astrophysics Data System (ADS)

    Kolb, Juergen F.; Price, Robert O.; Stacey, Michael; Swanson, R. James; Bowman, Angela; Chiavarini, Robert L.; Schoenbach, Karl H.

    2008-10-01

    By flowing ambient air through the discharge channel of a microhollow cathode geometry, we were able to sustain a stable 1.5-2 cm long afterglow plasma jet with dc voltages of only a few hundred volts. The temperature in this expelled afterglow plasma is close to room temperature. Emission spectra show atomic oxygen, hydroxyl ions and various nitrogen compounds. The low heavy-particle temperature allows us to use this exhaust stream on biological samples and tissues without thermal damage. The high levels of reactive species suggest an effective treatment for pathological skin conditions caused, in particular, by infectious agents. In first experiments, we have successfully tested the efficacy on Candida kefyr (a yeast), E.coli, and a matching E.coli strain-specific virus. All pathogens investigated responded well to the treatment. In the yeast case, complete eradication of the organism in the treated area could be achieved with an exposure of 90 seconds at a distance of 5 mm. A 10-fold increase of exposure, to 900 seconds caused no observable damage to murine integument.

  14. Analysis of the behavior of a discharge in a coaxial plasma jet accelerator

    NASA Astrophysics Data System (ADS)

    Voronin, A. V.; Gusev, V. K.; Gerasimenko, Ya. A.

    2013-03-01

    We analyze the behavior of the discharge in a coaxial plasma jet accelerator with a pulsed supply of the working gas released by an electric discharge from titanium hydride powder. Radiation (varying with time) from the discharge in the accelerator was detected using an optical method through a narrow slit cut along the outer electrode by a Bifo Company K008 streak camera. Stable operation of the source with the highest kinetic energy of a pure hydrogen plasma jet was attained for a relatively uniform glow of the discharge along the accelerator during the entire current pulse. Conversely, local glow of the discharge at the outlet or inlet of the accelerator considerably contaminated the discharge with impurities, and the kinetic energy of the plasma jet decreased by an order of magnitude. The highest energy of the plasma jet was attained when the polarity of the electrodes was the same as at the plasma focus.

  15. The impact of Hall physics on magnetized high energy density plasma jets

    SciTech Connect

    Gourdain, P.-A.; Seyler, C. E.; Atoyan, L.; Greenly, J. B.; Hammer, D. A.; Kusse, B. R.; Pikuz, S. A.; Potter, W. M.; Schrafel, P. C.; Shelkovenko, T. A.

    2014-05-15

    Hall physics is often neglected in high energy density plasma jets due to the relatively high electron density of such jets (n{sub e} ∼ 10{sup 19} cm{sup −3}). However, the vacuum region surrounding the jet has much lower densities and is dominated by Hall electric field. This electric field redirects plasma flows towards or away from the axis, depending on the radial current direction. A resulting change in the jet density has been observed experimentally. Furthermore, if an axial field is applied on the jet, the Hall effect is enhanced and ignoring it leads to serious discrepancies between experimental results and numerical simulations. By combining high currents (∼1 MA) and magnetic field helicity (15° angle) in a pulsed power generator such as COBRA, plasma jets can be magnetized with a 10 T axial field. The resulting field enhances the impact of the Hall effect by altering the density profile of current-free plasma jets and the stability of current-carrying plasma jets (e.g., Z-pinches)

  16. Contrasting characteristics of linear-field and cross-field atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

    Walsh, J. L.; Kong, M. G.

    2008-09-01

    This letter reports an experimental study of two types of atmospheric pressure plasma jets in terms of their fundamental properties and their efficiency in etching polymeric materials. The first plasma jet has a cross-field configuration with its electric field perpendicular to its gas flow field, whereas the second is a linear-field device having parallel electric and flow fields. The linear-field jet is shown to drive electron transportation to the downstream application region, thus facilitating more active plasma chemistry there. This is responsible for its etching rate of polyamide films being 13-fold that of its cross-field counterpart.

  17. Dynamical properties of non-equilibrium atmospheric plasma jets and their applications to plasma processing in liquids

    NASA Astrophysics Data System (ADS)

    Kitano, Katsuhisa; Satoshi, Ikawa; Furusho, Hitoshi; Nagasaki, Yukio; Hamaguchi, Satoshi

    2007-11-01

    Non-equilibrium atmospheric pressure plasma jets are discussed with the emphasis on their physics and applications. Plume-like plasmas, which may be called plasma jets, have been generated in a discharge system consisting of a dielectric/metal tube (through which He gas flows at the atmospheric pressure) and a single electrode attached to the tube, to which low-frequency, high-voltage pulses (˜10kV, ˜10kHz) are applied. With visible light images taken by a high-speed ICCD camera, it has been confirmed that the plasma jet consists of a series of small ``plasma bullets'' that are emitted intermittently from the powered electrode in sync with the positive voltage pulses. The observed ``plasma bullet'' may be interpreted as a fast moving ionization front. The plasma jets are energetic enough to generate highly reactive charge-neutral radicals but their gas temperatures remain low. Therefore the plasma jets are ideal for processing of liquid based materials at low temperatures and some examples of process applications, such as reduction of cations, polymerization of liquid monomers, and sterilization, will be also presented.

  18. Embedding magnetic field lines in the plasma jet of an exploding radial foil on COBRA

    NASA Astrophysics Data System (ADS)

    Schrafel, Peter; Gourdain, Pierre; Greenly, John; Kusse, Bruce

    2009-11-01

    Previous investigations of exploding radial foils have shown the formation of an axial plasma jet in the early stages of the foil explosion. In this case a thin load foil was pressed at an outer annulus held at ground, and contacted in the center by a small straight rod cathode driven by the 1MA COBRA accelerator. The present experiments look at the effects of inducing a transient magnetic field in the region containing the plasma jet. This induced magnetic field is created in one of two ways: twisting the rod cathode to have a helical coil segment near the foil, or putting an inductive current path in parallel to the straight rod cathode. Of great interest is whether this applied magnetic field can be embedded into the plasma jet and influence its development. The jet is diagnosed visually with laser shadowgraphy and observation of XUV emission. B-dot probes measure the magnetic field strength in the region near the jet.

  19. Interaction of a supersonic, radiatively cooled plasma jet with an ambient medium

    NASA Astrophysics Data System (ADS)

    Suzuki-Vidal, F.; Bocchi, M.; Lebedev, S. V.; Swadling, G. F.; Burdiak, G.; Bland, S. N.; de Grouchy, P.; Hall, G. N.; Harvey-Thompson, A. J.; Khoory, E.; Patankar, S.; Pickworth, L.; Skidmore, J.; Smith, R.; Chittenden, J. P.; Krishnan, M.; Madden, R. E.; Wilson-Elliot, K.; Ciardi, A.; Frank, A.

    2012-02-01

    An experimental investigation into the interaction of a supersonic, radiatively cooled plasma jet with argon gas is presented. The jet is formed by ablation of an aluminum foil driven by a 1.4 MA, 250 ns current pulse in a radial foil Z-pinch configuration. The outflow consists of a supersonic (Mach number ˜3-5), dense (ion density ni ˜ 1018 cm-3), highly collimated (half-opening angle ˜2°-5°) jet surrounded by a lower density halo plasma moving with the same axial velocity as the jet. The addition of argon above the foil leads to the formation of a shock driven by the ablation of halo plasma, together with a bow-shock driven by the dense jet. Experimental data with and without the presence of argon are compared with three-dimensional, magneto-hydrodynamic simulations using the GORGON code.

  20. Effects of water addition on OH radical generation and plasma properties in an atmospheric argon microwave plasma jet

    SciTech Connect

    Srivastava, Nimisha; Wang Chuji

    2011-09-01

    Water vapor was added to the feeding gas of a continuous atmospheric argon (Ar) microwave plasma jet to study its influence on plasma shape, plasma gas temperature, and OH radical concentrations. The plasma jet was created by a 2.45 GHz microwave plasma source operating at constant power of 104 W with H{sub 2}O-Ar mixture flow rate of 1.7 standard liter per minute (slm). With an increase in the H{sub 2}O/Ar ratio from 0.0 to 1.9%, the plasma jet column length decreased from 11 mm to 4 mm, and the plasma jet became unstable when the ratio was higher than 1.9%; elevation of plasma gas temperature up to 330 K was observed in the plasma temperature range of 420-910 K. Optical emission spectroscopy showed that the dominant plasma emissions changed from N{sub 2} in the pure Ar plasma jet to OH with the addition of water vapor, and simulations of emission spectra suggested non-Boltzmann distribution of the rotational levels in the OH A-state (v'=0). Spatially resolved absolute OH number densities along the plasma jet axis were measured using UV cavity ringdown spectroscopy of the OH (A-X) (0-0) band in the H{sub 2}O/Ar ratio range of 0.0-1.9%. The highest OH number density is consistently located in the vicinity of the plasma jet tip, regardless of the H{sub 2}O/Ar ratio. OH number density in the post-tip region follows approximately an exponential decay along the jet axis with the fastest decay constant of 3.0 mm in the H{sub 2}O/Ar ratio of 1.5%. Given the low gas temperature of 420-910 K and low electron temperature of 0.5-5 eV along the jet axis, formation of the OH radical is predominantly due to electron impact induced dissociation of H{sub 2}O and dissociative recombination of H{sub 2}O{sup +} resulting from the Penning ionization process.

  1. On the plasma chemistry of a cold atmospheric argon plasma jet with shielding gas device

    NASA Astrophysics Data System (ADS)

    Schmidt-Bleker, Ansgar; Winter, Jörn; Bösel, André; Reuter, Stephan; Weltmann, Klaus-Dieter

    2016-02-01

    A novel approach combining experimental and numerical methods for the study of reaction mechanisms in a cold atmospheric \\text{Ar} plasma jet is introduced. The jet is operated with a shielding gas device that produces a gas curtain of defined composition around the plasma plume. The shielding gas composition is varied from pure {{\\text{N}}2} to pure {{\\text{O}}2} . The density of metastable argon \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) in the plasma plume was quantified using laser atom absorption spectroscopy. The density of long-living reactive oxygen and nitrogen species (RONS), namely {{\\text{O}}3} , \\text{N}{{\\text{O}}2} , \\text{NO} , {{\\text{N}}2}\\text{O} , {{\\text{N}}2}{{\\text{O}}5} and {{\\text{H}}2}{{\\text{O}}2} , was quantified in the downstream region of the jet in a multipass cell using Fourier-transform infrared spectroscopy (FTIR). The jet produces a turbulent flow field and features guided streamers propagating at several \\text{km}~{{\\text{s}}-1} that follow the chaotic argon flow pattern, yielding a plasma plume with steep spatial gradients and a time dependence on the \\text{ns} scale while the downstream chemistry unfolds within several seconds. The fast and highly localized electron impact reactions in the guided streamer head and the slower gas phase reactions of neutrals occurring in the plasma plume and experimental apparatus are therefore represented in two separate kinetic models. The first electron impact reaction kinetics model is correlated to the LAAS measurements and shows that in the guided streamer head primary reactive oxygen and nitrogen species are dominantly generated from \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) . The second neutral species plug-flow model hence uses an \\text{Ar}≤ft(4\\text{s}{{,}3}{{\\text{P}}2}\\right) source term as sole energy input and yields good agreement with the RONS measured by FTIR spectroscopy.

  2. Discharge characteristics and hydrodynamics behaviors of atmospheric plasma jets produced in various gas flow patterns

    NASA Astrophysics Data System (ADS)

    Setsuhara, Yuichi; Uchida, Giichiro; Nakajima, Atsushi; Takenaka, Kosuke; Koga, Kazunori; Shiratani, Masaharu

    2015-09-01

    Atmospheric nonequilibrium plasma jets have been widely employed in biomedical applications. For biomedical applications, it is an important issue to understand the complicated mechanism of interaction of the plasma jet with liquid. In this study, we present analysis of the discharge characteristics of a plasma jet impinging onto the liquid surface under various gas flow patterns such as laminar and turbulence flows. For this purpose, we analyzed gas flow patters by using a Schlieren gas-flow imaging system in detail The plasma jet impinging into the liquid surface expands along the liquid surface. The diameter of the expanded plasma increases with gas flow rate, which is well explained by an increase in the diameter of the laminar gas-flow channel. When the gas flow rate is further increased, the gas flow mode transits from laminar to turbulence in the gas flow channel, which leads to the shortening of the plasm-jet length. Our experiment demonstrated that the gas flow patterns strongly affect the discharge characteristics in the plasma-jet system. This study was partly supported by a Grant-in-Aid for Scientific Research on Innovative Areas ``Plasma Medical Innovation'' (24108003) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).

  3. Cold atmospheric pressure plasma jets as sources of singlet delta oxygen for biomedical applications

    SciTech Connect

    Sousa, J. S.; Niemi, K.; Cox, L. J.; Algwari, Q. Th.; Gans, T.; O'Connell, D.

    2011-06-15

    Absolute densities of singlet delta oxygen (SDO) molecules were measured using infrared optical emission spectroscopy in the flowing effluents of two different atmospheric-pressure plasma jets (APPJs): a capacitively coupled radio-frequency-driven jet (rf-APPJ) and a lower frequency kilohertz-driven dielectric barrier discharge jet. The plasma jets were operated in helium, with small admixtures of molecular oxygen (O{sub 2} < 2%). High absolute SDO densities of up to 6.2 x 10{sup 15} cm{sup -3} were measured at approximately 10 cm downstream. The rf-APPJ seems to be much more efficient in producing SDO. The influence of different parameters, such as gas flows and mixtures and power coupled to the plasmas, on the production of SDO by the two APPJs has been investigated. Despite the considerable differences between the two plasma jets (excitation frequency, electric field direction, inter-electrode distance, plasma propagation), similar dependencies on the oxygen admixture and on the dissipated power were found in both APPJs. However, opposite trends were observed for the gas flow dependence. The results presented in this paper show that the control of the external operating conditions of each APPJ enables the tailoring of the SDO composition of both plasma effluents. This provides scope to tune the plasma jets for desired applications, e.g., in biomedicine.

  4. Ideal hydrodynamic scaling relations for a stagnated imploding spherical plasma liner formed by an array of merging plasma jets

    SciTech Connect

    Cassibry, J. T.; Stanic, M.; Hsu, S. C.

    2013-03-15

    This work presents scaling relations for the peak thermal pressure and stagnation time (over which peak pressure is sustained) for an imploding spherical plasma liner formed by an array of merging plasma jets. Results were derived from three-dimensional (3D) ideal hydrodynamic simulation results obtained using the smoothed particle hydrodynamics code SPHC. The 3D results were compared to equivalent one-dimensional (1D) simulation results. It is found that peak thermal pressure scales linearly with the number of jets and initial jet density and Mach number, quadratically with initial jet radius and velocity, and inversely with the initial jet length and the square of the chamber wall radius. The stagnation time scales approximately as the initial jet length divided by the initial jet velocity. Differences between the 3D and 1D results are attributed to the inclusion of thermal transport, ionization, and perfect symmetry in the 1D simulations. A subset of the results reported here formed the initial design basis for the Plasma Liner Experiment [S. C. Hsu et al., Phys. Plasmas 19, 123514 (2012)].

  5. Surface Modification of Material by Irradiation of Low Power Atmospheric Pressure Plasma Jet

    SciTech Connect

    Akamatsu, Hiroshi; Ichikawa, Kazunori; Azuma, Kingo; Onoi, Masahiro

    2010-10-13

    Application of a low power atmospheric pressure plasma jet for surface modifications of acrylic, aluminum, and highly crystalline graphite has been carried out experimentally. The plasma jet was generated with batteries-driven high voltage modulator. The power consumed for the plasma generation was estimated to be 0.12 W. The plasma had hydroxyl radicals, which is known as a strong oxider from an observation of optical emission spectrum. After the irradiation of the plasma, the surfaces of acrylic and aluminum became to be hydrophilic from the compartment of contact angle of water on these surfaces. The surface of highly crystalline graphite irradiated by the plasma jet had oxygen-rich functional groups such as C-O, C = O, and O = C-O.

  6. Disinfection of Staphylococcus Aureus by pulsed non-thermal atmospheric plasma jet

    NASA Astrophysics Data System (ADS)

    Mirpour, Shahriar; Ghoranneviss, Mahmood; Shahgoli, Farhad

    2011-10-01

    The aim of this paper was to study the effect of low-temperature atmospheric plasma jet on non-pathogenic bacteria's colonies. In this regard, Germicidal effect of time and distance of ICP He and He/N2 plasma jet on Staphylococcus Aureus were reported. The gas discharges were generated by a 40 KHz high voltage power supply which led to the inductively coupled plasma. The results showed that He/N2 enhance the sterilization time in comparison of He plasma. To the best of our knowledge this is the first study which has compared the effect of sterilization of ICP Helium and Helium-Nitrogen plasma in listed conditions. Also, the distance dependence showed that the germicidal effect was not linear the distance of electrode and sample. The protein leakage test and SEM of bacteria morphology confirmed the sterilization effect of non-thermal atmospheric pressure plasma jet.

  7. Note: Design and investigation of a multichannel plasma-jet triggered gas switch

    NASA Astrophysics Data System (ADS)

    Tie, Weihao; Liu, Xuandong; Zhang, Qiaogen; Liu, Shanhong

    2014-07-01

    We described the fabrication and testing of a multichannel plasma-jet triggered gas switch (MPJTGS). A novel six-channel annular micro-plasma-gun was embedded in the trigger electrode to generate multichannel plasma jets as a nanosecond trigger pulse arrived. The gas breakdown in multiple sites of the spark gap was induced and fixed around jet orifices by the plasma jets. We tested the multichannel discharge characteristics of the MPJTGS in two working modes with charge voltage of 50 kV, trigger voltage of +40 kV (25 ns rise time), and trigger energy of 240 J, 32 J, and 2 J, respectively, at different working coefficients. Results show that the average number of discharge channels increased as the trigger energy increased, and decreased as the working coefficient decreased. At a working coefficient of 87.1% and trigger energy of 240 J, the average number of discharge channels in Mode II could reach 4.1.

  8. FAST TRACK COMMUNICATION: Effects of Penning ionization on the discharge patterns of atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Li, Qing; Zhu, Wen-Chao; Zhu, Xi-Ming; Pu, Yi-Kang

    2010-09-01

    Atmospheric pressure plasma jets, generated in a coaxial dielectric barrier discharge configuration, have been investigated with different flowing gases. Discharge patterns in different tube regions were compared in the flowing gases of helium, neon and krypton. To explain the difference of these discharge patterns, a theoretical analysis is presented to reveal the possible basic processes. A comparison of experimental and theoretical results identifies that Penning ionization is mainly responsible for the discharge patterns of helium and neon plasma jets.

  9. Synthesis of Silane and Silicon in a Non-equilibrium Plasma Jet

    NASA Technical Reports Server (NTRS)

    Calcote, H. F.

    1978-01-01

    The original objective of this program was to determine the feasibility of high volume, low-cost production of high purity silane or solar cell grade silicon using a non equilibrium plasma jet. The emphasis was changed near the end of the program to determine the feasibility of preparing photovoltaic amorphous silicon films directly using this method. The non equilibrium plasma jet should be further evaluated as a technique for producing high efficiency photovoltaic amorphous silicon films.

  10. Review on VUV to MIR absorption spectroscopy of atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Reuter, Stephan; Santos Sousa, Joao; Stancu, Gabi Daniel; Hubertus van Helden, Jean-Pierre

    2015-10-01

    Absorption spectroscopy (AS) represents a reliable method for the characterization of cold atmospheric pressure plasma jets. The method’s simplicity stands out in comparison to competing diagnostic techniques. AS is an in situ, non-invasive technique giving absolute densities, free of calibration procedures, which other diagnostics, such as laser-induced fluorescence or optical emission spectroscopy, have to rely on. Ground state densities can be determined without the knowledge of the influence of collisional quenching. Therefore, absolute densities determined by absorption spectroscopy can be taken as calibration for other methods. In this paper, fundamentals of absorption spectroscopy are presented as an entrance to the topic. In the second part of the manuscript, a review of AS performed on cold atmospheric pressure plasma jets, as they are used e.g. in the field of plasma medicine, is presented. The focus is set on special techniques overcoming not only the drawback of spectrally overlapping absorbing species, but also the line-of-sight densities that AS usually provides or the necessity of sufficiently long absorption lengths. Where references are not available for measurements on cold atmospheric pressure plasma jets, other plasma sources including low-pressure plasmas are taken as an example to give suggestions for possible approaches. The final part is a table summarizing examples of absorption spectroscopic measurements on cold atmospheric pressure plasma jets. With this, the paper provides a ‘best practice’ guideline and gives a compendium of works by groups performing absorption spectroscopy on cold atmospheric pressure plasma jets.

  11. The plasma footprint of an atmospheric pressure plasma jet on a flat polymer substrate and its relation to surface treatment

    NASA Astrophysics Data System (ADS)

    Onyshchenko, Iuliia; Nikiforov, Anton Yu.; De Geyter, Nathalie; Morent, Rino

    2016-08-01

    The aim of this work is to show the correlation between the plasma propagation in the footprint of an atmospheric pressure plasma jet on a flat polymer surface and the plasma treatment impact on the polymer properties. An argon plasma jet working in open air is used as plasma source, while PET thin films are used a substrates for plasma treatment. Light emission photographs are taken with an ICCD camera to have a close look at the generated structures in the plasma jet footprint on the surface. Water contact angle (WCA) measurement and X-ray photoelectron spectroscopy (XPS) analysis are also performed to obtain information about the impact of the plasma treatment on the PET surface characteristics. A variation in ICCD camera gate duration (1 µs, 100 µs, 50 ms) results in the photographs of the different plasma structures occurring during the plasma propagation on the flat PET surface. Contact angle measurements provide results on improvement of the PET hydrophilic character, while XPS analysis shows the distribution of atomic elements on the treated substrate surface. Light emission images help explaining the obtained WCA and XPS results. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  12. Two discharge modes in an atmospheric pressure plasma jet array in argon

    NASA Astrophysics Data System (ADS)

    Fang, Zhi; Ruan, Chen; Shao, Tao; Zhang, Cheng

    2016-02-01

    In this paper, the generation and discharge modes of 2D atmospheric pressure plasma jet arrays in economic argon feeding gas with a honeycomb configuration is first reported. Two coupling and collimated discharge modes are achieved with the same array structure. The discharge modes are shown to depend on the gas flow rate and center-to-center distances of jets in the array. Stronger plasmas with higher plasma density than single jet can be obtained in coupling mode array at close proximity of jets in the array and small gas flow rate, while plasmas with moderate plasma density and relative large area can be obtained in the collimated mode array at far proximity of jets in the array. The power density and emission spectra from the centered plasma jet for the coupling mode array are both larger than those of the collimated mode. The appearance of the two discharge modes may be due to the hydrodynamic interactions between the seven individual Ar channels emerging from individual tubes with the air surrounding them.

  13. Numerical simulation of alumina spraying in argon-helium plasma jet

    NASA Astrophysics Data System (ADS)

    Chang, C. H.

    A numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Particle-plasma interactions including turbulent dispersion have been modeled in a fully self-consistent manner. Interactions between the plasma and the torch and substrate walls are modeled using wall functions.

  14. FAST TRACK COMMUNICATION: Modelling of streamer propagation in atmospheric-pressure helium plasma jets

    NASA Astrophysics Data System (ADS)

    Naidis, G. V.

    2010-10-01

    The results of a two-dimensional numerical simulation of positive streamer propagation in atmospheric-pressure helium jets injected into ambient air are presented. It is shown that depending on the jet width and the initial radial distribution of electron number density streamer structures of two types can be formed: one with maxima of electric field and electron density at the jet axis and another with maxima of these parameters near the boundary between the jet and surrounding air. The latter structure is similar to the observed ring-shaped structures of plasma bullets.

  15. Sterilization of bacterial endospores by an atmospheric-pressure argon plasma jet

    SciTech Connect

    Uhm, Han S.; Lim, Jin P.; Li, Shou Z.

    2007-06-25

    Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. However, the spore-killing efficiency of the atmospheric-pressure argon-oxygen jet depends very sensitively on the oxygen concentration in the argon gas.

  16. Experimental characterization of a transition from collisionless to collisional interaction between head-on-merging supersonic plasma jets

    SciTech Connect

    Moser, Auna L. Hsu, Scott C.

    2015-05-15

    We present results from experiments on the head-on merging of two supersonic plasma jets in an initially collisionless regime for the counter-streaming ions. The plasma jets are of either an argon/impurity or hydrogen/impurity mixture and are produced by pulsed-power-driven railguns. Based on time- and space-resolved fast-imaging, multi-chord interferometry, and survey-spectroscopy measurements of the overlapping region between the merging jets, we observe that the jets initially interpenetrate, consistent with calculated inter-jet ion collision lengths, which are long. As the jets interpenetrate, a rising mean-charge state causes a rapid decrease in the inter-jet ion collision length. Finally, the interaction becomes collisional and the jets stagnate, eventually producing structures consistent with collisional shocks. These experimental observations can aid in the validation of plasma collisionality and ionization models for plasmas with complex equations of state.

  17. Thermalization of mini-jets in a quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Iancu, Edmond; Wu, Bin

    2016-03-01

    We present the complete physical picture for the evolution of a high-energy jet propagating through a weakly-coupled quark-gluon plasma (QGP) by analytical and numerical investigation of thermalization of the soft components of the jet. Our results support the following physical picture: the leading particle emits a significant number of mini-jets which promptly evolve via multiple branching and thus degrade into a myriad of soft gluons, with energies of the order of the medium temperature T. Via elastic collisions with the medium constituents, these soft gluons relax to local thermal equilibrium with the plasma over a time scale which is considerably shorter than the typical lifetime of the mini-jet. The thermalized gluons form a tail which lags behind the hard components of the jet. Together with the background QGP, they behave hydrodynamically.

  18. A hypersonic plasma bullet train traveling in an atmospheric dielectric-barrier discharge jet

    SciTech Connect

    Shi Jianjun; Zhong Fangchun; Zhang Jing; Liu, D. W.; Kong, M. G.

    2008-01-15

    An experimental observation of fast-moving plasma bullets produced in an atmospheric dielectric-barrier discharge jet is reported in this paper. Nanosecond imaging suggests that the atmospheric discharge jet consists of a plasma bullet train traveling at a hypersonic speed from 7.0 km/s to 43.1 km/s. Yet on a millisecond scale, the bullet train appears as a plasma jet of several centimeters long. The plasma bullets are produced through several possible mechanisms, the most likely of which is related to the ionization wave. Time and space resolved optical emission spectroscopy show that reactive plasma species can be delivered to different spatial sites with varying quantities.

  19. Numerical and experimental study on a pulsed-dc plasma jet

    NASA Astrophysics Data System (ADS)

    Liu, X. Y.; Pei, X. K.; Lu, X. P.; Liu, D. W.

    2014-06-01

    A numerical and experimental study of plasma jet propagation in a low-temperature, atmospheric-pressure, helium jet in ambient air is presented. A self-consistent, multi-species, two-dimensional axially symmetric plasma model with detailed finite-rate chemistry of helium-air mixture composition is used to provide insights into the propagation of the plasma jet. The obtained simulation results suggest that the sheath forms near the dielectric tube inner surface and shields the plasma channel from the tube surface. The strong electric field at the edge of the dielectric field enhances the ionization in the air mixing layer; therefore, the streamer head becomes ring-shaped when the streamer runs out of the tube. The avalanche-to-streamer transition is the main mechanism of streamer advancement. Penning ionization dominates the ionization reactions and increases the electrical conductivity of the plasma channel. The simulation results are supported by experimental observations under similar discharge conditions.

  20. Modeling of strongly collimated jets produced by high energy density plasmas on COBRA

    NASA Astrophysics Data System (ADS)

    Gourdain, P.-A.; Seyler, C. E.

    2014-03-01

    Jet collimation in astrophysical plasmas and in the laboratory has recently received much attention. When the magnetohydrodynamics (MHD) model is used to represent both systems, scale invariance allows for the simple extension of the parameters encountered in laboratory experiments to much larger systems, like astrophysical outflows. However, the validation of such a model requires a precise comparison of numerical simulations with experimental data. Using radial foils as an experimental setup to generate strongly collimated plasma jets, we show that the Hall MHD model included in the PERSEUS code does well to capture the plasma dynamics of collimated jets, even with restrictive conditions such as a constant ionization number and the neglect of normally important transport processes. Very importantly, we show that jet collimation is not only the result of magnetic forces, but also converging radial flows.

  1. Collisional-radiative simulations of a supersonic and radiatively cooled aluminum plasma jet

    NASA Astrophysics Data System (ADS)

    Espinosa, G.; Gil, J. M.; Rodriguez, R.; Rubiano, J. G.; Mendoza, M. A.; Martel, P.; Minguez, E.; Suzuki-Vidal, F.; Lebedev, S. V.; Swadling, G. F.; Burdiak, G.; Pickworth, L. A.; Skidmore, J.

    2015-12-01

    A computational investigation based on collisional-radiative simulations of a supersonic and radiatively cooled aluminum plasma jet is presented. The jet, both in vacuum and in argon ambient gas, was produced on the MAGPIE (Mega Ampere Generator for Plasma Implosion Experiments) generator and is formed by ablation of an aluminum foil driven by a 1.4 MA, 250 ns current pulse in a radial foil Z-pinch configuration. In this work, population kinetics and radiative properties simulations of the jet in different theoretical approximations were performed. In particular, local thermodynamic equilibrium (LTE), non-LTE steady state (SS) and non-LTE time dependent (TD) models have been considered. This study allows us to make a convenient microscopic characterization of the aluminum plasma jet.

  2. Modeling of the merging, liner formation, implosion of hypervelocity plasma jets for the PLX- α project

    NASA Astrophysics Data System (ADS)

    Cassibry, Jason; Hsu, Scott; Schillo, Kevin; Samulyak, Roman; Stoltz, Peter; Beckwith, Kris

    2015-11-01

    A suite of numerical tools will support the conical and 4 π plasma-liner-formation experiments for the PLX- α project. A new Lagrangian particles (LP) method will provide detailed studies of the merging of plasma jets and plasma-liner formation/convergence. A 3d smooth particle hydrodynamic (SPH) code will simulate conical (up to 9 jets) and 4 π spherical (up to 60 jets) liner formation and implosion. Both LP and SPH will use the same tabular EOS generated by Propaceos, thermal conductivity, optically thin radiation and physical viscosity models. With LP and SPH,the major objectives are to study Mach-number degradation during jet merging, provide RMS amplitude and wave number of the liner nonuniformity at the leading edge, and develop scaling laws for ram pressure and liner uniformity as a function of jet parameters. USIM, a 3D multi-fluid plasma code, will be used to perform 1D and 2D simulations of plasma-jet-driven magneto-inertial fusion (PJMIF) to identify initial conditions in which the ``liner gain'' exceeds unity. A brief overview of the modeling program will be provided. Results from SPH modeling to support the PLX- α experimental design will also be presented, including preliminary ram-pressure scaling and non-uniformity characterization.

  3. Studies of Jet Outflow from Advanced Beam-Driven FRC Plasma on C-2U

    NASA Astrophysics Data System (ADS)

    Sheftman, Daniel; Gupta, Deepak; Giammanco, Francesco; Conti, Fabio; Marsili, Paolo

    2015-11-01

    Experiments demonstrating sustainment of field-reversed configuration (FRC) plasma via neutral beam injection have been carried out on C-2U. Knowledge and control of the axial outflow of plasma particles and energy through open-magnetic-field lines are of crucial importance to the stability and longevity of the advanced beam-driven FRC plasma. Passive Doppler spectroscopy and microwave interferometry measurements provide an initial view of the behavior of the open-field-line plasmas on the C-2U device. These measurements and estimations of plasma density, flow velocity, excluded-magnetic flux, and ion temperature of the jet outflow plasmas are discussed. In addition, possible contributions from fast-ion losses from the advanced beam-driven FRC plasma to the jet will be explored and presented.

  4. Helium Atmospheric Pressure Plasma Jet: Diagnostics and Application for Burned Wounds Healing

    NASA Astrophysics Data System (ADS)

    Topala, Ionut; Nastuta, Andrei

    A new field of plasma applications developed in the last years, entitled plasma medicine, has focused the attention of many peoples from plasma ­community on biology and medicine. Subjects that involve plasma physics and technology (e.g. living tissue treatment or wound healing, cancer cell apoptosis, blood coagulation, sterilization and decontamination) are nowadays in study in many laboratories. In this paper we present results on optical and electrical diagnosis of a helium ­atmospheric pressure plasma jet designed for medical use. This type of plasma jet was used for improvement of the wound healing process. We observed a more rapid macroscopic healing of the plasma treated wounds in comparison with the control group.

  5. Atmospheric nonequilibrium mini-plasma jet created by a 3D printer

    SciTech Connect

    Takamatsu, Toshihiro; Kawano, Hiroaki; Miyahara, Hidekazu; Okino, Akitoshi; Azuma, Takeshi

    2015-07-15

    In this study, a small-sized plasma jet source with a 3.7 mm head diameter was created via a 3D printer. The jet’s emission properties and OH radical concentrations (generated by argon, helium, and nitrogen plasmas) were investigated using optical emission spectrometry (OES) and electron spin resonance (ESR). As such, for OES, each individual gas plasma propagates emission lines that derive from gases and ambient air inserted into the measurement system. For the case of ESR, a spin adduct of the OH radical is typically observed for all gas plasma treatment scenarios with a 10 s treatment by helium plasma generating the largest amount of OH radicals at 110 μM. Therefore, it was confirmed that a plasma jet source made by a 3D printer can generate stable plasmas using each of the aforementioned three gases.

  6. Interaction of multiple atmospheric-pressure micro-plasma jets in small arrays: He/O2 into humid air

    NASA Astrophysics Data System (ADS)

    Babaeva, Natalia Yu; Kushner, Mark J.

    2014-02-01

    Arrays of atmospheric-pressure plasma jets are being considered as a means to increase the area being treated in surface modification and in plasma medicine in particular. A unique challenge of scaling plasma jet arrays is that individual plasma jets in an array tend to interact with each other, which can lead to quenching of some individual jets. To investigate these potential interactions, a computational study of one-, two- and three-tube arrays of micro-plasma jet arrays was performed. An atmospheric-pressure He/O2 = 99.8/0.2 mixture was flowed through the tubes into humid room air. We found that the jets interact through electrostatic, hydrodynamic and photolytic means. The hydrodynamic interactions result from the merging of individual He channels emerging from individual tubes as air diffuses into the extended gas jets. Ionization waves (IWs) or plasma bullets, which form the jets on the boundaries of an array, encounter higher mole fractions of air earlier compared with the center jet and so are slower or are quenched earlier. The close proximity of the jets produces electrostatic repulsion, which affects the trajectories of the IWs. If the jets are close enough, photoionizing radiation from their neighbors is an additional form of interaction. These interactions are sensitive to the spacing of the jets.

  7. Modeling the plasma chemistry of stratospheric Blue Jet streamers

    NASA Astrophysics Data System (ADS)

    Winkler, Holger; Notholt, Justus

    2014-05-01

    Stratospheric Blue Jets (SBJs) are upward propagating discharges in the altitude range 15-40 km above thunderstorms. The currently most accepted theory associates SBJs to the development of the streamer zone of a leader. The streamers emitted from the leader can travel for a few tens of kilometers predominantly in the vertical direction (Raizer et al., 2007). The strong electric fields at the streamer tips cause ionisation, dissociation, and excitation, and give rise to chemical perturbations. While in recent years the effects of electric discharges occurring in the mesosphere (sprites) have been investigated in a number of model studies, there are only a few studies on the impact of SBJs. However, chemical perturbations due to SBJs are of interest as they might influence the stratospheric ozone layer. We present results of detailed plasma chemistry simulations of SBJ streamers for both day-time and night-time conditions. Any effects of the subsequent leader are not considered. The model accounts for more than 500 reactions and calculates the evolution of the 88 species under the influence of the breakdown electric fields at the streamer tip. As the SBJ dynamics is outside the scope of this study, the streamer parameters are prescribed. For this purpose, electric field parameters based on Raizer et al. (2007) are used. The model is applied to the typical SBJ altitude range 15-40 km. The simulations indicate that SBJ streamers cause significant chemical perturbations. In particular, the liberation of atomic oxygen during the discharge leads to a formation of ozone. At the same time, reactive nitrogen and hydrogen radicals are produced which will cause catalytic ozone destruction. Reference: Raizer et al. (2007), J. Atmos. Solar-Terr. Phys., 69 (8), 925-938.

  8. Multi-electrodes Atmospheric Pressure Plasma Jet Aiming Bio-applications

    NASA Astrophysics Data System (ADS)

    Han, Jeon G.; Sahu, B. B.; Shin, K. S.; Lee, J. S.; Hori, M.

    2015-09-01

    For the recent advancement in the field of plasma medicine, there is growing demand for the atmospheric-pressure plasma (APP) jet sources with desired plasma characteristics. In this study, a stable non-thermal low-voltage APP jet device was designed and developed for optical and electrical characterizations. The jet was operated at very low frequency in the range 10-40 KHz, which enabled the generation of low power (~ 7W) plasma with a plasma column diameter of about 5 mm. The jet has a visible radial diameter of approximately 10 mm. Optical emission spectroscopy was used as a diagnostic tool to investigate the generation of plasmas and radical species. Discharge parameters are also measured to evaluate the different operating conditions. The gas temperature measured at the substrate location varies from 300 to 315 K for different gases where the electrical input power ranged from 1 to 7 W. The highly reactive species like OH, O, N2, N2 + and along with the trace of NO are characterized with respect to the different gas flow rate of Ar/He/O2/N2, applied voltages, duty cycles and frequencies to evaluate the capability of the APP jet for future bio-applications.

  9. Atmospheric pressure resistive barrier air plasma jet induced bacterial inactivation in aqueous environment

    NASA Astrophysics Data System (ADS)

    Thiyagarajan, Magesh; Sarani, Abdollah; Gonzales, Xavier

    2013-03-01

    An atmospheric pressure resistive barrier air plasma jet is designed to inactivate bacteria in aqueous media in direct and indirect exposure modes of treatment. The resistive barrier plasma jet is designed to operate at both dc and standard 50-60 Hz low frequency ac power input and the ambient air at 50% humidity level was used as the operating gas. The voltage-current characteristics of the plasma jet were analyzed and the operating frequency of the discharge was measured to be 20 kHz and the plasma power was measured to be 26 W. The plasma jet rotational temperatures (Trot) are obtained from the optical emission spectra, from the N2C-B(2+) transitions by matching the experimental spectrum results with the Spectra Air (SPECAIR) simulation spectra. The reactive oxygen and nitrogen species were measured using optical emission spectroscopy and gas analyzers, for direct and indirect treatment modes. The nitric oxides (NO) were observed to be the predominant long lived reactive nitrogen species produced by the plasma. Three different bacteria including Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Neisseria meningitidis (Gram-negative) were suspended in an aqueous media and treated by the resistive barrier air plasma jet in direct and indirect exposure modes. The results show that a near complete bacterial inactivation was achieved within 120 s for both direct and indirect plasma treatment of S. aureus and E. coli bacteria. Conversely, a partial inactivation of N. meningitidis was observed by 120 s direct plasma exposure and insignificant inactivation was observed for the indirect plasma exposure treatment. Plasma induced shifts in N. meningitidis gene expression was analyzed using pilC gene expression as a representative gene and the results showed a reduction in the expression of the pilC gene compared to untreated samples suggesting that the observed protection against NO may be regulated by other genes.

  10. C60-Fullerene Hyper-Velocity High-Density Plasma Jets for MIF and Disruption Mitigation

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Galkin, S. A.; Kim, J. S.

    2009-06-01

    We present an innovative idea to use hyper-velocity (>30 km/s) high-density (>1017 cm-3) plasma jets of D-T/H and C60-fullerene for magneto-inertial fusion (MIF), high energy density laboratory plasma (HEDLP), and disruption mitigation in magnetic fusion plasma devices. The mass (~1-2 g) of sublimated C60 and hydrogen (or D-T fuel) produced in a pulsed power source is ionized and accelerated as a plasma slug in a coaxial plasma accelerator. For MIF/HEDLP we propose to create a magnetized plasma target by injecting two high-Mach number high-density jets with fuel (D-T) and liner (C60/C) structure along the axis of a pulsed magnetic mirror. The magnetized target fusion (MTF) plasma created by head-on collision and stagnation of jets is compressed radially by a metallic liner (Z-pinch) and axially by the C60/C liner. For disruption mitigation, the C60 plasma jets were shown to be able to provide the required impurity mass (J Fusion Energy 27:6, 2008).

  11. The nature of fluctuations in a double arc argon-nitrogen plasma jet

    SciTech Connect

    Tu Xin; Yan Jianhua; Yu Liang; Cen, Kefa; Cheron, Bruno

    2007-09-24

    The dynamic behavior of the double arc argon-nitrogen plasma jet is investigated by combined means of the fast Fourier transform, correlation function, and Wigner distribution. The restrike mode is identified as the fluctuation behavior in an argon-nitrogen plasma jet. The Fourier spectra exhibit two characteristic frequencies of 150 Hz and 4.1 kHz, which indicates that the nature of fluctuations in the double arc argon-nitrogen plasma can be ascribed to the power supply undulation and both arc roots motion on the anode channels. It is further found that the double anode torch could inhibit and reduce the restrike phenomenon.

  12. Surface modification of Raw and Frit glazes by non-thermal helium plasma jet

    NASA Astrophysics Data System (ADS)

    Ghasemi, M.; Sohbatzadeh, F.; Mirzanejhad, S.

    2015-06-01

    In this study, non-thermal atmospheric pressure plasma jet (APPJ) was utilized to improve the adhesion of Raw and Frit glazes. These glazes are widely used in industry to make chinaware, decorative dishes and tiles applied at wall and floor. As they should be painted before use, increasing their adhesive properties leads to a better paint durability. Electrical and optical characteristics of the plasma jet are investigated to optimize for efficient treatment. Contact angle measurement and surface energy calculation demonstrate a drastic increase after the plasma treatment indicating wettability and paintability enhancement. Moreover, atomic force microscopy and X-ray photoelectron spectroscopy analyses were performed on the specimens to explore the influence of helium plasma jet on the physical and chemical properties of the glazes, microscopically. AFM analysis reveals surface etching resulted from the bombardment of the solid surfaces by the APPJ using helium fed gas. The process aims to enhance adhesive properties of glaze surfaces.

  13. Study of non-thermal plasma jet with dielectric barrier configuration in nitrogen and argon

    NASA Astrophysics Data System (ADS)

    Choo, C. Y.; Chin, O. H.

    2014-03-01

    Dielectric barrier discharge (DBD) is advantageous in generating non-thermal plasma at atmospheric pressure, as it avoids transition to thermal arc and dispenses with costly vacuum system. It has found useful applications in treating heat-sensitive materials such as plastics and living tissue. In this work, the discharge formed between the Pyrex glass layer and the ground electrode is extruded through a nozzle to form the non-thermal plasma jet. The DBD characteristics were investigated in terms of charge transferred and mean power dissipated per cycle when operated in nitrogen and argon at various flow rates and applied voltages. These characteristics were then correlated to the dimension of the plasma jet. The mean power dissipated in the DBD was below 7 W giving an efficiency of 17 %. The length of the plasma jet was greatly limited to below 1 cm due to the configuration of the DBD system and nozzle.

  14. Hybrid PIC Simulations of Particle Dynamics in Coaxial Plasma Jet Accelerators

    NASA Astrophysics Data System (ADS)

    Thoma, Carsten; Hughes, Thomas; Welch, Dale; Hakel, Peter

    2007-11-01

    We describe the results of 1D and 2D simulations of plasma jet accelerators using the particle-in-cell (PIC) code Lsp. Previous studies of 1D cartesian simulations have shown that ion particle dynamics at the plasma-vacuum interface depend critically on the local Hall parameter, which is strongly dependent on electron temperature. In a coaxial accelerator with finite transverse dimensions, large transverse ion motions, predicted at moderate Hall parameters in 1D, can lead to ion loss to the walls. The results of 2D r-z jet simulations are described and compared with the 1D cartesian results. The effects of particle loss and ablation at the wall are considered, as are electron heating mechanisms at the plasma-vacuum interface, including radiation losses. We will apply the results to the plasma jet experiments underway at HyperV Technologies Corp.

  15. Experimental Characterization of Magnetogasdynamic Phenomena in Ultra-High Velocity Pulsed Plasma Jets

    NASA Astrophysics Data System (ADS)

    Loebner, Keith; Wang, Benjamin; Cappelli, Mark

    2014-10-01

    The formation and propagation of high velocity plasma jets in a pulsed, coaxial, deflagration-type discharge is examined experimentally. A sensitive, miniaturized, immersed probe array is used to map out magnetic flux density and associated radial current density as a function of time and axial position. This array is also used to probe the magnetic field gradient across the exit of the accelerator and in the jet formation region. Sensitive interferometry via a continuous-wave helium-neon laser source is used to probe the structure of the plasma jet over multiple chords and axial locations. A two dimensional plasma density gradient profile at an instant in time during jet formation is compiled via Shack-Hartmann wavefront sensor analysis. The qualitative characteristics of rarefaction and/or shock wave formation as a function of chamber back-pressure is examined via fast-framing ICCD imaging. These measurements are compared to existing resistive MHD simulations of the coaxial deflagration accelerator and the ensuing rarefaction jet that is expelled from the electrode assembly. The physical mechanisms governing the behavior of the discharge and the formation of these high energy density plasma jets are proposed and validated against both theoretical models and numerically simulated behavior. This research was conducted with Government support under and awarded by DoD, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168a.

  16. Comparison between helium and argon plasma jets on improving the hydrophilic property of PMMA surface

    NASA Astrophysics Data System (ADS)

    Wang, Ruixue; Shen, Yuan; Zhang, Cheng; Yan, Ping; Shao, Tao

    2016-03-01

    In this paper, a plasma jet driven by an in-house developed microsecond pulse is used for polymethyl methacrylate (PMMA) surface modification. The hydrophilic modification effects of He and Ar plasma jets are compared under the same condition. The He and Ar plasma jets are characterized by optical emission spectrometer (OES). Water contact angle (WCA) measurement is used to evaluate the wettability of PMMA samples. The evolution on morphology and chemical composition of PMMA before and after plasma treatment are also analyzed. The OES results demonstrate that He plasma is composed with higher intensities of reactive species, like OH, O, N2 and N2+ than that of Ar plasma and show a better modification effect. In addition, it is observed that the surface roughness and oxygen-containing groups like Csbnd O/Csbnd OH and Odbnd Csbnd O increase on the PMMA surface after plasma treatment, which are responsible for the hydrophilic modification. During the storage, the WCA of each sample increases gradually for both He and Ar plasma treatments. The He plasma treated PMMA also shows a slower aging effect than that of Ar plasma treated PMMA.

  17. Ram-pressure scaling and non-uniformity characterization of a spherically imploding liner formed by hypervelocity plasma jets

    NASA Astrophysics Data System (ADS)

    Cassibry, Jason; Dougherty, Jesse; Thompson, Seth; Hsu, Scott; Witherspoon, F. D.; University of AL in Huntsville Team; Los Alamos National Laboratory Team; HyperV Technologies Corp. Team

    2014-10-01

    Three-dimensional modeling of plasma liner formation and implosion is performed using the Smoothed Particle Hydrodynamics Code (SPHC) with radiation, thermal transport, and tabular equations of state (EOS), accounting for ionization, in support of a proposed 60-gun plasma liner formation experiment for plasma-jet driven magneto-inertial fusion (PJMIF). Previous SPHC modeling showed that ideal gas law scaling of peak stagnation pressure increased linearly with density and number of jets, quadratically with jet radius and velocity, and inversely with the initial jet length, while results with tabular EOS, thermal transport, and radiation have greater sensitivity to the initial jet distribution. A series of simulations are conducted to study the effects of initial jet conditions on peak ram pressure and liner non-uniformity during plasma liner implosion. The growth rate of large-amplitude density perturbations introduced by the discrete jets are computed and compared with predictions by the Bell-Plesset equation.

  18. Effect of pulse polarity on the temporal and spatial emission of an atmospheric pressure helium plasma jet

    NASA Astrophysics Data System (ADS)

    Wang, Ruixue; Zhang, Kai; Shen, Yuan; Zhang, Cheng; Zhu, Weidong; Shao, Tao

    2016-02-01

    A single needle-electrode plasma jet driven by a home-made microsecond pulse power supply is studied. The electrical characteristics and optical emissions of the plasma jets driven by positive- and negative-polarity pulses are compared. With the same magnitude of applied voltage, the plasma jet driven by positive pulses shows a higher discharge current, a higher optical emission intensity and travels to a longer distance. The temporal-spatially resolved He (706.5 nm), N2 (337.1 nm) and \\text{N}2+ (391.4 nm) emissions behave differently in the plasma jets driven by different polarity pulses: They appear to be discrete emission packets in the positive plasma jet, but continuous emission in the negative plasma jet (under the time resolution in this study). The emission front propagates at a faster speed in the positive plasma jet than in the negative plasma jet. The different behavior of the plasma jets is attributed to the electric field distribution under different polarity pulses.

  19. LIF and fast imaging plasma jet characterization relevant for NTP biomedical applications

    NASA Astrophysics Data System (ADS)

    Riès, D.; Dilecce, G.; Robert, E.; Ambrico, P. F.; Dozias, S.; Pouvesle, J.-M.

    2014-07-01

    In the field of biomedical application, many publications report on non-thermal plasma jet potentialities for cell behaviour modifications in cancer treatment, wound healing or sterilization. However most previous plasma jet characterizations were performed when jets expend freely in air. Only recently has the influence of the targeted surface been properly considered. In this work, modifications induced by various types of targets, mimicking the biological samples, in the plasma propagation and production of hydroxyl radicals are evidenced through time-resolved intensified charge-coupled device imaging and laser-induced fluorescence (LIF) measurements. A LIF model, also specifically dedicated to estimate air and water penetration inside the jet, is used and proves to be well adapted to characterize the plasma jet under biomedical application conditions. It is shown that the plasma produced by the plasma gun counter-propagates after impinging the surface which, for the same operating parameters, leads to an increase of almost one order of magnitude in the maximum OH density (from ˜2 × 1013 cm-3 for open-air propagation to ˜1 × 1014 cm-3 for a grounded metal target). The nature of the target, especially its electrical conductivity, as well as gas flow rate and voltage amplitude are playing a key role in the production of hydroxyl radicals. The strong interplay between gas flow dynamics and plasma propagation is here confirmed by air and water distribution measurements. The need for a multi-diagnostic approach, as well as great care in setting up the in situ characterization of plasma jets, is here emphasized. Special attention must not only be paid to voltage amplitude and gas flow rate but also to the nature, humidity and conductivity of the target.

  20. Atmospheric pressure plasma jet with high-voltage power supply based on piezoelectric transformer

    SciTech Connect

    Babij, Michał; Kowalski, Zbigniew W. Nitsch, Karol; Gotszalk, Teodor; Silberring, Jerzy

    2014-05-15

    The dielectric barrier discharge plasma jet, an example of the nonthermal atmospheric pressure plasma jet (APPJ), generates low-temperature plasmas that are suitable for the atomization of volatile species and can also be served as an ionization source for ambient mass and ion mobility spectrometry. A new design of APPJ for mass spectrometry has been built in our group. In these plasma sources magnetic transformers (MTs) and inductors are typically used in power supplies but they present several drawbacks that are even more evident when dealing with high-voltage normally used in APPJs. To overcome these disadvantages, high frequency generators with the absence of MT are proposed in the literature. However, in the case of miniaturized APPJs these conventional power converters, built of ferromagnetic cores and inductors or by means of LC resonant tank circuits, are not so useful as piezoelectric transformer (PT) based power converters due to bulky components and small efficiency. We made and examined a novel atmospheric pressure plasma jet with PT supplier served as ionization source for ambient mass spectrometry, and especially mobile spectrometry where miniaturization, integration of components, and clean plasma are required. The objective of this paper is to describe the concept, design, and implementation of this miniaturized piezoelectric transformer-based atmospheric pressure plasma jet.

  1. Timescale and magnitude of plasma thermal energy loss before and during disruptions in JET

    NASA Astrophysics Data System (ADS)

    Riccardo, V.; Loarte, A.; JET EFDA Contributors

    2005-11-01

    In this paper we analyse and discuss the thermal energy loss dynamics before and during JET disruptions that occurred between 2002 and 2004 in discharges which reached >4.5 MJ of thermal energy. We observe the slow thermal energy transients with diamagnetic loops and the fast ones with electron cyclotron emission and soft x-ray diagnostics. For most disruption types in JET, the plasma thermal energy at the time of the thermal quench is substantially less than that of the full performance plasma, typically in the range of 10-50% depending on plasma conditions and disruption type. The exceptions to this observation are disruptions in plasmas with a strong internal transport barrier (ITB) and in discharges terminating in a pure vertical displacement event, in which the plasma conserves a very high energy content up to the thermal quench. These disruption types are very sudden, leaving little scope for the combined action of soft plasma landing strategies and intrinsic performance degradation, both requiring >500 ms to be effective, to decrease the available thermal energy. The characteristic time for the loss of energy from the main plasma towards the PFCs in the thermal quench of JET disruptions is in the range 0.05-3.0 ms. The shortest timescales are typical of disruptions caused by excessive pressure peaking in ITB discharges. The available thermal energy fraction and thermal quench duration observed in JET can be processed (with due caution) into estimates for the projected PFC lifetime of the ITER target.

  2. Atmospheric pressure plasma jet with high-voltage power supply based on piezoelectric transformer.

    PubMed

    Babij, Michał; Kowalski, Zbigniew W; Nitsch, Karol; Silberring, Jerzy; Gotszalk, Teodor

    2014-05-01

    The dielectric barrier discharge plasma jet, an example of the nonthermal atmospheric pressure plasma jet (APPJ), generates low-temperature plasmas that are suitable for the atomization of volatile species and can also be served as an ionization source for ambient mass and ion mobility spectrometry. A new design of APPJ for mass spectrometry has been built in our group. In these plasma sources magnetic transformers (MTs) and inductors are typically used in power supplies but they present several drawbacks that are even more evident when dealing with high-voltage normally used in APPJs. To overcome these disadvantages, high frequency generators with the absence of MT are proposed in the literature. However, in the case of miniaturized APPJs these conventional power converters, built of ferromagnetic cores and inductors or by means of LC resonant tank circuits, are not so useful as piezoelectric transformer (PT) based power converters due to bulky components and small efficiency. We made and examined a novel atmospheric pressure plasma jet with PT supplier served as ionization source for ambient mass spectrometry, and especially mobile spectrometry where miniaturization, integration of components, and clean plasma are required. The objective of this paper is to describe the concept, design, and implementation of this miniaturized piezoelectric transformer-based atmospheric pressure plasma jet. PMID:24880391

  3. Atmospheric pressure plasma jets interacting with liquid covered tissue: touching and not-touching the liquid

    NASA Astrophysics Data System (ADS)

    Norberg, Seth A.; Tian, Wei; Johnsen, Eric; Kushner, Mark J.

    2014-11-01

    In the use of atmospheric pressure plasma jets in biological applications, the plasma-produced charged and neutral species in the plume of the jet often interact with a thin layer of liquid covering the tissue being treated. The plasma-produced reactivity must then penetrate through the liquid layer to reach the tissue. In this computational investigation, a plasma jet created by a single discharge pulse at three different voltages was directed onto a 200 µm water layer covering tissue followed by a 10 s afterglow. The magnitude of the voltage and its pulse length determined if the ionization wave producing the plasma plume reached the surface of the liquid. When the ionization wave touches the surface, significantly more charged species were created in the water layer with H3O+aq, O3-aq, and O2-aq being the dominant terminal species. More aqueous OHaq, H2O2aq, and O3aq were also formed when the plasma plume touches the surface. The single pulse examined here corresponds to a low repetition rate plasma jet where reactive species would be blown out of the volume between pulses and there is not recirculation of flow or turbulence. For these conditions, NxOy species do not accumulate in the volume. As a result, aqueous nitrites, nitrates, and peroxynitrite, and the HNO3aq and HOONOaq, which trace their origin to solvated NxOy, have low densities.

  4. FAR-TECH's Nanoparticle Plasma Jet System and its Application to Disruptions, Deep Fueling, and Diagnostics

    NASA Astrophysics Data System (ADS)

    Thompson, J. R.; Bogatu, I. N.; Galkin, S. A.; Kim, J. S.

    2012-10-01

    Hyper-velocity plasma jets have potential applications in tokamaks for disruption mitigation, deep fueling and diagnostics. Pulsed power based solid-state sources and plasma accelerators offer advantages of rapid response and mass delivery at high velocities. Fast response is critical for some disruption mitigation scenario needs, while high velocity is especially important for penetration into tokamak plasma and its confining magnetic field, as in the case of deep fueling. FAR-TECH is developing the capability of producing large-mass hyper-velocity plasma jets. The prototype solid-state source has produced: 1) >8.4 mg of H2 gas only, and 2) >25 mg of H2 and >180 mg of C60 in a H2/C60 gas mixture. Using a coaxial plasma gun coupled to the source, we have successfully demonstrated the acceleration of composite H/C60 plasma jets, with momentum as high as 0.6 g.km/s, and containing an estimated C60 mass of ˜75 mg. We present the status of FAR-TECH's nanoparticle plasma jet system and discuss its application to disruptions, deep fueling, and diagnostics. A new TiH2/C60 solid-state source capable of generating significantly higher quantities of H2 and C60 in <0.5 ms will be discussed.

  5. LES of a Jet Excited by the Localized Arc Filament Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Brown, Clifford A.

    2011-01-01

    The fluid dynamics of a high-speed jet are governed by the instability waves that form in the free-shear boundary layer of the jet. Jet excitation manipulates the growth and saturation of particular instability waves to control the unsteady flow structures that characterize the energy cascade in the jet.The results may include jet noise mitigation or a reduction in the infrared signature of the jet. The Localized Arc Filament Plasma Actuators (LAFPA) have demonstrated the ability to excite a high-speed jets in laboratory experiments. Extending and optimizing this excitation technology, however, is a complex process that will require many tests and trials. Computational simulations can play an important role in understanding and optimizing this actuator technology for real-world applications. Previous research has focused on developing a suitable actuator model and coupling it with the appropriate computational fluid dynamics (CFD) methods using two-dimensional spatial flow approximations. This work is now extended to three-dimensions (3-D) in space. The actuator model is adapted to a series of discrete actuators and a 3-D LES simulation of an excited jet is run. The results are used to study the fluid dynamics near the actuator and in the jet plume.

  6. The role of MHD in causing impurity peaking in JET hybrid plasmas

    NASA Astrophysics Data System (ADS)

    Hender, T. C.; Buratti, P.; Casson, F. J.; Alper, B.; Baranov, Yu. F.; Baruzzo, M.; Challis, C. D.; Koechl, F.; Lawson, K. D.; Marchetto, C.; Nave, M. F. F.; Pütterich, T.; Reyes Cortes, S.; Contributors, JET

    2016-06-01

    In hybrid plasma operation in JET with its ITER-like wall (JET-ILW) it is found that n  >  1 tearing activity can significantly enhance the rate of on-axis peaking of high-Z impurities, which in turn significantly degrades discharge performance. Core n  =  1 instabilities can be beneficial in removing impurities from the plasma core (e.g. sawteeth or fishbones), but can conversely also degrade core confinement (particularly in combination with simultaneous n  =  3 activity). The nature of magnetohydrodynamic instabilities in JET hybrid discharges, with both its previous carbon wall and subsequent JET-ILW, is surveyed statistically and the character of the instabilities is examined. Possible qualitative models for how the n  >  1 islands can enhance the on-axis impurity transport accumulation processes are presented.

  7. Destruction of {alpha}-synuclein based amyloid fibrils by a low temperature plasma jet

    SciTech Connect

    Karakas, Erdinc; Laroussi, Mounir; Munyanyi, Agatha; Greene, Lesley

    2010-10-04

    Amyloid fibrils are ordered beta-sheet aggregates that are associated with a number of neurodegenerative diseases such as Alzheimer and Parkinson. At present, there is no cure for these progressive and debilitating diseases. Here we report initial studies that indicate that low temperature atmospheric pressure plasma can break amyloid fibrils into smaller units in vitro. The plasma was generated by the 'plasma pencil', a device capable of emitting a long, low temperature plasma plume/jet. This avenue of research may facilitate the development of a plasma-based medical treatment.

  8. Characterization of an atmospheric pressure plasma jet and its applications for disinfection and cancer treatment.

    PubMed

    Thiyagarajan, Magesh; Sarani, Abdollah; Gonzales, Xavier F

    2013-01-01

    In this work an atmospheric pressure non-thermal resistive barrier (RB) plasma jet was constructed, characterized and was applied for biomedical applications. The RB plasma source can operate in both DC (battery) as well as in standard 60/50 Hz low frequency AC excitation, and it functions effectively in both direct and indirect plasma exposure configurations. The characteristics of the RB plasma jet such as electrical properties, plasma gas temperature and nitric oxides concentration were determined using voltage-current characterization, optical emission spectroscopy and gas analyzer diagnostic techniques. Plasma discharge power of 26.33 W was calculated from voltage-current characterization. An optical emission spectroscopy was applied and the gas temperature which is equivalent to the nitrogen rotational (Trot) temperatures was measured. The concentrations of the reactive oxygen species at different spatial distances from the tip of the plasma jet were measured and the ppm concentration of NO is at the preferred level for a wide range of standard biomedical treatment applications. The ppm values of nitric oxides after the cooling unit are observed to be of the same order of magnitude as compared to plasma jet. The portable RB plasma source was tested to be very effective for decontamination and disinfection of a wide range of foodborne and opportunistic nosocomial pathogens such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus cereus and the preliminary results are presented. The effects of indirect exposure of the portable RBP source on monocytic leukemia cancer cells (THP-1) were also tested and the results demonstrate that a preference for apoptosis in plasma treated THP-1 cells under particular plasma parameters and dosage levels. PMID:23400199

  9. Coherent anti-Stokes Raman spectroscopic measurement of air entrainment in argon plasma jets

    SciTech Connect

    Fincke, J.R.; Rodriquez, R.; Pentecost, C.G.

    1990-01-01

    The concentration and temperature of air entrained into an argon plasma jet has been measured using coherent anti-Stokes Raman spectroscopy (CARS). The flow field is characterized by a short region of well behaved laminar flow near the nozzle exit followed by an abrupt transition to turbulence. Once the transition to turbulence occurs, air is rapidly entrained into the jet core. The location of the transition region is thought to be driven by the rapid cooling of the jet and the resulting increase in Reynolds number. 8 refs., 6 figs.

  10. Coherent anti-Stokes Raman spectroscopic measurement of air entrainment in argon plasma jets

    NASA Astrophysics Data System (ADS)

    Fincke, J. R.; Rodriquez, R.; Pentecost, C. G.

    The concentration and temperature of air entrained into an argon plasma jet has been measured using coherent anti-Stokes Raman spectroscopy (CARS). The flow field is characterized by a short region of well behaved laminar flow near the nozzle exit followed by an abrupt transition to turbulence. Once the transition to turbulence occurs, air is rapidly entrained into the jet core. The location of the transition region is thought to be driven by the rapid cooling of the jet and the resulting increase in Reynolds number.

  11. Plasma Jets Driven by Ultraintense-Laser Interaction with Thin Foils

    SciTech Connect

    Kar, S.; Borghesi, M.; Romagnani, L.; Bulanov, S. V.; Key, M. H.; Mackinnon, A. J.; Patel, P. K.; Liseykina, T. V.; Macchi, A.; Schiavi, A.; Willi, O.

    2008-06-06

    Experimental evidence of plasma jets ejected from the rear side of thin solid targets irradiated by ultraintense (>10{sup 19} W cm{sup -2}) laser pulses is presented. The jets, detected by transverse interferometric measurements with high spatial and temporal resolutions, show collimated expansion lasting for several hundreds of picoseconds and have substantially steep density gradients at their periphery. The role played by radiation pressure of the laser in the jet formation process is highlighted analytically and by extensive two-dimensional particle-in-cell simulations.

  12. Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets

    SciTech Connect

    Merritt, Elizabeth C. Adams, Colin S.; Moser, Auna L.; Hsu, Scott C. Dunn, John P.; Miguel Holgado, A.; Gilmore, Mark A.

    2014-05-15

    We report spatially resolved measurements of the oblique merging of two supersonic laboratory plasma jets. The jets are formed and launched by pulsed-power-driven railguns using injected argon, and have electron density ∼10{sup 14} cm{sup −3}, electron temperature ≈1.4 eV, ionization fraction near unity, and velocity ≈40 km/s just prior to merging. The jet merging produces a few-cm-thick stagnation layer, as observed in both fast-framing camera images and multi-chord interferometer data, consistent with collisional shock formation [E. C. Merritt et al., Phys. Rev. Lett. 111, 085003 (2013)].

  13. Interfacial Stability of Spherically Converging Plasma Jets for Magnetized Target Fusion

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Cassibry, Jason; Wu, S. T.; Eskridge, Richard; Smith, James; Lee, Michael; Rodgers, Stephen L. (Technical Monitor)

    2000-01-01

    A fusion propulsion scheme has been proposed that makes use of the merging of a spherical distribution of plasma jets to dynamically form a gaseous liner to implode a magnetized target to produce the fusion reaction. In this paper, a study is made of the interfacial stability of the interaction of these jets. Specifically, the Orr-Sommerfeld equation is integrated to obtain the growth rate of a perturbation to the primary flow at the interface between the colliding jets. The results lead to an estimate on the tolerances on the relative flow velocities of the merging plasma jets to form a stable, imploding liner. The results show that the maximum temporal growth rate of the perturbed flow at the jet interface is very small in comparison with the time to full compression of the liner. These data suggest that, as far as the stability of the interface between the merging jets is concerned, the formation of the gaseous liner can withstand velocity variation of the order of 10% between the neighboring jets over the density and temperature ranges investigated.

  14. Thermalization of mini-jets in a quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Iancu, Edmond; Wu, Bin

    2015-10-01

    We complete the physical picture for the evolution of a high-energy jet propagating through a weakly-coupled quark-gluon plasma by investigating the thermalization of the soft components of the jet. We argue that the following scenario should hold: the leading particle emits a significant number of mini-jets which promptly evolve via quasi-democratic branchings and thus degrade into a myriad of soft gluons, with energies of the order of the medium temperature T. Via elastic collisions with the medium constituents, these soft gluons relax to local thermal equilibrium with the plasma over a time scale which is considerably shorter than the typical lifetime of the mini-jet. The thermalized gluons form a tail which lags behind the hard components of the jet. We support this scenario, first, via parametric arguments and, next, by studying a simplified kinetic equation, which describes the jet dynamics in longitudinal phase-space. We solve the kinetic equation using both (semi-)analytical and numerical methods. In particular, we obtain the first exact, analytic, solutions to the ultrarelativistic Fokker-Planck equation in one-dimensional phase-space. Our results confirm the physical picture aforementioned and demonstrate the quenching of the jet via multiple branching followed by the thermalization of the soft gluons in the cascades.

  15. Control of Shock-Induced Boundary Layer Separation by using Pulsed Plasma Jets

    NASA Astrophysics Data System (ADS)

    Greene, Benton R.; Clemens, Noel T.; Micka, Daniel

    2012-11-01

    Shock-induced turbulent boundary layer separation can have many detrimental effects in supersonic flow including flow instability, fatigue of structural panels, and unstart in supersonic inlets. Pulsed plasma jets (or ``spark jets''), which are characterized by high bandwidth and the ability to direct momentum into the flow, are one promising method of reducing shock-induced separation. The current study is focused on investigating the efficacy of plasma jets to reduce the separated flow induced by a compression ramp in a Mach 3 flow. Three different 3-jet actuator configurations are tested: 20° pitched, 45° pitched, and 22° pitched and 45° skewed. The jets are pulsed at frequencies between 2 kHz and 4 kHz with duty cycles between 5 and 15%. The shock wave is generated using a 20° compression ramp, and the location of the shock-induced separation is visualized using surface oil streak visualization as well as particle image velocimetry. The results of the study show that of the three configurations, the plasma jets pitched at 20° from the streamwise direction cause the greatest reduction in separation, and when pulsed at a frequency of 3.2 kHz and 12% duty cycle can reduce the size of the separation region by up to 40%. This work is supported by AFRL under SBIR contract.

  16. Effect of Pulsed Plasma Jets on Reflected Shock-Turbulent Boundary Layer Interaction

    NASA Astrophysics Data System (ADS)

    Greene, Benton R.; Clemens, Noel T.; Magari, Patrick; Micka, Daniel

    2013-11-01

    Shock-induced turbulent boundary layer separation can have many detrimental effects in supersonic inlets including flow instability, fatigue of structural panels, poor pressure recovery, and unstart. Pulsed plasma jets (or ``spark jets''), zero net mass flow jets characterized by high bandwidth and the ability to direct momentum into the flow, are one promising method of reducing shock-induced separation and boundary layer distortion. The current study is focused on investigating the efficacy of pulsed plasma jets to reduce the boundary layer distortion induced by a reflected shock interaction in a Mach 3 flow. A 7° shock generator placed outside the tunnel ceiling boundary layer produces an incident shock on the floor of the tunnel of sufficient strength to induce separation. An array of pulsed plasma jets are placed approximately 2 boundary layer thicknesses upstream of the interaction and pulsed at between 1 kHz and 4 kHz. PIV is used to investigate the effect of the jets on the nature of the separation as well as the boundary layer distortion and pressure recovery downstream of the interaction. Funded through AFRL in collaboration with Creare, Inc.

  17. Two-dimensional numerical study of two counter-propagating helium plasma jets in air at atmospheric pressure

    SciTech Connect

    Yan, Wen; Sang, Chaofeng; Wang, Dezhen; Liu, Fucheng

    2014-06-15

    In this paper, a computational study of two counter-propagating helium plasma jets in ambient air is presented. A two-dimensional fluid model is applied to investigate the physical processes of the two plasma jets interaction (PJI) driven by equal and unequal voltages, respectively. In all studied cases, the PJI results in a decrease of both plasma bullets propagation velocity. When the two plasma jets are driven by equal voltages, they never merge but rather approach each other around the middle of the gas gap at a minimum approach distance, and the minimal distance decreases with the increase of both the applied voltages and initial electron density, but increases with the increase of the relative permittivity. When the two plasma jets are driven by unequal voltages, we observe the two plasma jets will merge at the position away from the middle of the gas gap. The effect of applied voltage difference on the PJI is also studied.

  18. GYRO Simulations of Core Momentum Transport in DIII-D and JET Plasmas

    SciTech Connect

    R.V. Budny; J. Candy; R.E. Waltz; and contributors to the DIII-D and JET-EFDA work programs

    2005-06-27

    Momentum, energy, and particle transport in DIII-D and JET ELMy H-mode plasmas is simulated with GYRO and compared with measurements analyzed using TRANSP. The simulated transport depends sensitively on the nabla(T(sub)i) turbulence drive and the nabla(E(sub)r) turbulence suppression inputs. With their nominal values indicated by measurements, the simulations over-predict the momentum and energy transport in the DIII-D plasmas, and under-predict in the JET plasmas. Reducing |nabla(T(sub)i)| and increasing |nabla(E(sub)r)| by up to 15% leads to approximate agreement (within a factor of two) for the DIII-D cases. For the JET cases, increasing |nabla(T(sub)i)| or reducing |nabla(E(sub)r)| results in approximate agreement for the energy flow, but the ratio of the simulated energy and momentum flows remains higher than measurements by a factor of 2-4.

  19. Atmospheric pressure plasma jets: an overview of devices and new directions

    NASA Astrophysics Data System (ADS)

    Winter, J.; Brandenburg, R.; Weltmann, K.-D.

    2015-12-01

    Atmospheric pressure plasma jets have a long history of more than 50 years. During this time their design and plasma generation mechanism has been developed and adapted to various fields of applications. This review aims at giving an overview of jet devices by starting with a brief history of their development. This is followed by an overview of commonly used terms and definitions as well as a survey of different classification schemes (e.g. geometry, excition frequency or specific energy input) described in literature. A selective update of new designs and novel research achievments on atmospheric pressure plasma jets published in 2012 or later shows the impressive variety and rapid development of the field. Finally, a brief outlook on the future trends and directions is given.

  20. Patterned graphene functionalization via mask-free scanning of micro-plasma jet under ambient condition

    SciTech Connect

    Ye, Dong; Yu, Yao Liu, Lin; Wu, Shu-Qun; Lu, Xin-Pei; Wu, Yue

    2014-03-10

    In this work, a mask-free method is introduced for patterned nitrogen doping of graphene using a micro-plasma jet under ambient condition. Raman and X-ray photoelectron spectroscopy spectra indicate that nitrogen atoms are incorporated into the graphene lattice with the two-dimensional spatial distribution precisely controlled in the range of mm down to 10 μm. Since the chemistry of the micro-plasma jet can be controlled by the choice of the gas mixture, this direct writing process with micro-plasma jet can be a versatile approach for patterned functionalization of graphene with high spatial resolution. This could have promising applications in graphene-based electronics.

  1. Characterization of a novel double-gas-jet laser plasma EUV source

    NASA Astrophysics Data System (ADS)

    de Bruijn, Rene; Bartnik, Andrzej; Fledderus, H. F.; Fiedorowicz, Henryk; Hegeman, Petra; Constantinescu, Raluca C.; Bijkerk, Fred

    2000-07-01

    A novel laser plasma EUV source geometry based on a (pulsed) double gas jet system has been characterized for utilization in EUV Lithography. The use of a secondary annular jet of a buffer gas in conjunction with the primary jet of target gas provides a considerable gain in EUV yield of an order of magnitude. The best CE data at 12.8 nm were obtained using xenon as target gas and hydrogen as buffer gas. The plasma source was driven using a short-wavelength KrF laser (0.9 J, 27 ns). Conversion efficiencies (CE) and EUV pulse shapes have been measured using calibrated Mo/Si multilayer mirrors and filtered junction diodes. A pinhole camera, equipped with a back illuminated CCD camera, was used to determine the plasma size in a wavelength range from 6 - 16 nm.

  2. Absolute OH density determination by laser induced fluorescence spectroscopy in an atmospheric pressure RF plasma jet

    NASA Astrophysics Data System (ADS)

    Xiong, Q.; Nikiforov, A. Yu.; Li, L.; Vanraes, P.; Britun, N.; Snyders, R.; Lu, X. P.; Leys, C.

    2012-11-01

    In this paper, the ground state OH density is measured in high pressure plasma by laser-induced fluorescence (LIF) spectroscopy. The OH density determination is based on the simulation of the intensity fraction of fluorescence from the laser-excited level of OH (A) in the total detected LIF signal. The validity of this approach is verified in an atmospheric pressure Ar + H2O plasma jet sustained by a 13.56 MHz power supply. The transition line P1 (4) from OH (A, v' = 1, J' = 3) → OH (X, v'' = 0, J'' = 4) is used for the LIF excitation. The absolute OH density is determined to be 2.5 × 1019 m-3 at 1 mm away from the jet nozzle. It corresponds to a dissociation of 0.06% of the water vapor in the working gas. Different mechanisms of OH (X) production in the core of the plasma jet are discussed and analyzed.

  3. Hybrid-PIC Algorithms for Simulation of Large-Scale Plasma Jet Accelerators

    NASA Astrophysics Data System (ADS)

    Thoma, Carsten; Welch, Dale

    2009-11-01

    Merging coaxial plasma jets are envisioned for use in magneto-inertial fusion schemes as the source of an imploding plasma liner. An experimental program at HyperV is considering the generation of large plasma jets (length scales on the order of centimeters) at high densities (10^16-10^17 cm-3) in long coaxial accelerators. We describe the Hybrid particle-in-cell (PIC) methods implemented in the code LSP for this parameter regime and present simulation results of the HyperV accelerator. A radiation transport algorithm has also been implemented into LSP so that the effect of radiation cooling on the jet mach number can be included self-consistently into the Hybrid PIC formalism.

  4. Axial Magnetic Field Compression within Radial Foil Plasma Jets, Experiment and Simulation

    NASA Astrophysics Data System (ADS)

    Byvank, Tom; Potter, William; Chang, Jae Young; Banasek, Jacob; Greenly, John; Seyler, Charles; Kusse, Bruce

    2015-11-01

    Compression of an axial magnetic field correlates with density hollowing and azimuthal rotation of a plasma jet generated by the COBRA pulsed power machine (1 MA peak current in 100 ns rise time) in a radial foil (15 μm Al thin disk) configuration. The plasma jet compresses an external 1 T axial magnetic field (Bz) as it collimates along the central z-axis. Experimental measurements use a Bdot magnetic probe placed in the center of the hollow plasma jet. Experimental results show compression of the 1 T Bz field to 2.4 +/- 0.3 T. Predictions made by the extended magnetohydrodynamics (XMHD) code, PERSEUS, show a 5.0 +/- 0.7 T field at the probe location. We overview physical reasons for the discrepancy between the experimental and simulation magnetic field compression measurements.

  5. Turbulent jet flow generated downstream of a low temperature dielectric barrier atmospheric pressure plasma device.

    PubMed

    Whalley, Richard D; Walsh, James L

    2016-01-01

    Flowing low temperature atmospheric pressure plasma devices have been used in many technological applications ranging from energy efficient combustion through to wound healing and cancer therapy. The generation of the plasma causes a sudden onset of turbulence in the inhomogeneous axisymmetric jet flow downstream of the plasma plume. The mean turbulent velocity fields are shown to be self-similar and independent of the applied voltage used to generate the plasma. It is proposed that the production of turbulence is related to a combination of the small-amplitude plasma induced body forces and gas heating causing perturbations in the unstable shear layers at the jet exit which grow as they move downstream, creating turbulence. PMID:27561246

  6. Turbulent jet flow generated downstream of a low temperature dielectric barrier atmospheric pressure plasma device

    PubMed Central

    Whalley, Richard D.; Walsh, James L.

    2016-01-01

    Flowing low temperature atmospheric pressure plasma devices have been used in many technological applications ranging from energy efficient combustion through to wound healing and cancer therapy. The generation of the plasma causes a sudden onset of turbulence in the inhomogeneous axisymmetric jet flow downstream of the plasma plume. The mean turbulent velocity fields are shown to be self-similar and independent of the applied voltage used to generate the plasma. It is proposed that the production of turbulence is related to a combination of the small-amplitude plasma induced body forces and gas heating causing perturbations in the unstable shear layers at the jet exit which grow as they move downstream, creating turbulence. PMID:27561246

  7. Experimental characterization of railgun-driven supersonic plasma jets motivated by high energy density physics applications

    SciTech Connect

    Hsu, S. C.; Moser, A. L.; Awe, T. J.; Davis, J. S.; Dunn, J. P.; Merritt, E. C.; Adams, C. S.; Brockington, S. J. E.; Case, A.; Messer, S. J.; Witherspoon, F. D.; Cassibry, J. T.; Gilmore, M. A.; Lynn, A. G.

    2012-12-15

    We report experimental results on the parameters, structure, and evolution of high-Mach-number (M) argon plasma jets formed and launched by a pulsed-power-driven railgun. The nominal initial average jet parameters in the data set analyzed are density Almost-Equal-To 2 Multiplication-Sign 10{sup 16} cm{sup -3}, electron temperature Almost-Equal-To 1.4 eV, velocity Almost-Equal-To 30 km/s, M Almost-Equal-To 14, ionization fraction Almost-Equal-To 0.96, diameter Almost-Equal-To 5 cm, and length Almost-Equal-To 20 cm. These values approach the range needed by the Plasma Liner Experiment, which is designed to use merging plasma jets to form imploding spherical plasma liners that can reach peak pressures of 0.1-1 Mbar at stagnation. As these jets propagate a distance of approximately 40 cm, the average density drops by one order of magnitude, which is at the very low end of the 8-160 times drop predicted by ideal hydrodynamic theory of a constant-M jet.

  8. Killing of adherent oral microbes by a non-thermal atmospheric plasma jet.

    PubMed

    Rupf, Stefan; Lehmann, Antje; Hannig, Matthias; Schäfer, Barbara; Schubert, Andreas; Feldmann, Uwe; Schindler, Axel

    2010-02-01

    Atmospheric plasma jets are being intensively studied with respect to potential applications in medicine. The aim of this in vitro study was to test a microwave-powered non-thermal atmospheric plasma jet for its antimicrobial efficacy against adherent oral micro-organisms. Agar plates and dentin slices were inoculated with 6 log(10) c.f.u. cm(-2) of Lactobacillus casei, Streptococcus mutans and Candida albicans, with Escherichia coli as a control. Areas of 1 cm(2) on the agar plates or the complete dentin slices were irradiated with a helium plasma jet for 0.3, 0.6 or 0.9 s mm(-2), respectively. The agar plates were incubated at 37 degrees C, and dentin slices were vortexed in liquid media and suspensions were placed on agar plates. The killing efficacy of the plasma jet was assessed by counting the number of c.f.u. on the irradiated areas of the agar plates, as well as by determination of the number of c.f.u. recovered from dentin slices. A microbe-killing effect was found on the irradiated parts of the agar plates for L. casei, S. mutans, C. albicans and E. coli. The plasma-jet treatment reduced the c.f.u. by 3-4 log(10) intervals on the dentin slices in comparison to recovery rates from untreated controls. The microbe-killing effect was correlated with increasing irradiation times. Thus, non-thermal atmospheric plasma jets could be used for the disinfection of dental surfaces. PMID:19910483

  9. 3D Mapping of plasma effective areas via detection of cancer cell damage induced by atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Han, Xu; Liu, Yueing; Stack, M. Sharon; Ptasinska, Sylwia

    2014-12-01

    In the present study, a nitrogen atmospheric pressure plasma jet (APPJ) was used for irradiation of oral cancer cells. Since cancer cells are very susceptible to plasma treatment, they can be used as a tool for detection of APPJ-effective areas, which extended much further than the visible part of the APPJ. An immunofluorescence assay was used for DNA damage identification, visualization and quantification. Thus, the effective damage area and damage level were determined and plotted as 3D images.

  10. Friction and wear properties of Ti6Al4V/WC-Co in cold atmospheric plasma jet

    NASA Astrophysics Data System (ADS)

    Xu, Wenji; Liu, Xin; Song, Jinlong; Wu, Libo; Sun, Jing

    2012-10-01

    The friction and wear properties of Ti6Al4V/WC-Co friction pair were studied using an autonomous atmospheric pressure bare electrode cold plasma jet generating device and block-on-ring friction/wear tester, respectively. The study was conducted under air, air jet, nitrogen jet, air cold plasma jet, and nitrogen cold plasma jet atmospheres. Both nitrogen cold and air cold plasma jets effectively reduced the friction coefficients of the friction pairs and decreased friction temperature. The friction coefficient in the nitrogen cold plasma jet decreased to almost 60% compared with that in the air. The scanning electron microscope, energy-dispersive X-ray spectroscope, and X-ray diffraction analyses illustrated that adhesive wear was relieved and the friction surfaces of Ti6Al4V were smoother, both in the nitrogen cold and air cold plasma jets. The roughness value Ra of the Ti6Al4V friction surfaces can reach 1.107 μm. A large number of nitrogen particles in the ionic and excited states contained by cold plasma jets reacts easily on the friction surface to produce a large amount of nitrides, which can excellently reduce the wear of Ti6Al4V/WC-Co friction pairs in real-time.

  11. Nanocapillary Atmospheric Pressure Plasma Jet: A Tool for Ultrafine Maskless Surface Modification at Atmospheric Pressure.

    PubMed

    Motrescu, Iuliana; Nagatsu, Masaaki

    2016-05-18

    With respect to microsized surface functionalization techniques we proposed the use of a maskless, versatile, simple tool, represented by a nano- or microcapillary atmospheric pressure plasma jet for producing microsized controlled etching, chemical vapor deposition, and chemical modification patterns on polymeric surfaces. In this work we show the possibility of size-controlled surface amination, and we discuss it as a function of different processing parameters. Moreover, we prove the successful connection of labeled sugar chains on the functionalized microscale patterns, indicating the possibility to use ultrafine capillary atmospheric pressure plasma jets as versatile tools for biosensing, tissue engineering, and related biomedical applications. PMID:27116255

  12. Modelling of plasma-edge and plasma-wall interaction physics at JET with the metallic first-wall

    NASA Astrophysics Data System (ADS)

    Wiesen, S.; Groth, M.; Brezinsek, S.; Wischmeier, M.; contributors, JET

    2016-02-01

    An overview is given on the recent progress on edge modelling activities for the JET ITER-like wall using the computational tools like the SOLPS or EDGE2D-EIRENE code. The validation process of these codes on JET with its metallic plasma-facing components is an important step towards predictive studies for ITER and DEMO in relevant divertor operational conditions, i.e., for detached, radiating divertors. With increased quantitative credibility in such codes more reliable input to plasma-wall and plasma-material codes can be warranted, which in turn results in more realistic and physically sound estimates of the life-time expectations and performance of a Be first-wall and a W-divertor, the same materials configuration foreseen for ITER. A brief review is given on the recent achievements in the plasma-wall interaction and material migration studies. Finally, a short summary is given on the availability and development of integrated codes to assess the performance of an JET-ILW baseline scenario also in view of the preparation for a JET DT-campaign.

  13. Atmospheric pressure plasma jet for bacterial decontamination and property improvement of fruit and vegetable processing wastewater

    NASA Astrophysics Data System (ADS)

    Mohamed, Abdel-Aleam H.; Shariff, Samir M. Al; Ouf, Salama A.; Benghanem, Mohamed

    2016-05-01

    An atmospheric pressure plasma jet was tested for decontaminating and improving the characteristics of wastewater derived from blackberry, date palm, tomato and beetroot processing industries. The jet was generated by blowing argon gas through a cylindrical alumina tube while a high voltage was applied between two electrodes surrounding the tube. Oxygen gas was mixed with argon at the rate of 0.2% and the argon mass flow was fixed at 4.5 slm. Images show that the generated plasma jet penetrated the treated wastewater samples. Plasma emission spectra show the presence of O and OH radicals as well as excited molecular nitrogen and argon. Complete decontamination of wastewater derived from date palm and tomato processing was achieved after 120 and 150 s exposure to the plasma jet, respectively. The bacterial count of wastewater from blackberry and beetroot was reduced by 0.41 and 2.24 log10 colony-forming units (CFU) per ml, respectively, after 180 s. Escherichia coli was the most susceptible bacterial species to the cold plasma while Shigella boydii had the minimum susceptibility, recording 1.30 and 3.34 log10 CFU ml‑1, respectively, as compared to the 7.00 log10 initial count. The chemical oxygen demands of wastewater were improved by 57.5–93.3% after 180 s exposure to the plasma jet being tested. The endotoxins in the wastewater were reduced by up to 90.22%. The variation in plasma effectiveness is probably related to the antioxidant concentration of the different investigated wastewaters.

  14. Inductive Measurement of Plasma Jet Electrical Conductivity (MSFC Center Director's discretionary Fund). Part 2

    NASA Technical Reports Server (NTRS)

    Turner, M. W.; Hawk, C. W.; Litchford, R. J.

    2001-01-01

    Measurement of plasma jet electrical conductivity has utility in the development of explosively driven magnetohydrodynamic (MHD) energy converters as well as magnetic flux compression reaction chambers for nuclear/chemical pulse propulsion and power. Within these types of reactors, the physical parameter of critical importance to underlying MHD processes is the magnetic Reynolds number, the value of which depends upon the product of plasma electrical conductivity and velocity. Therefore, a thorough understanding of MHD phenomena at high magnetic Reynolds number is essential, and methods are needed for the accurate and reliable measurement of electrical conductivity in high-speed plasma jets. It is well known that direct measurements using electrodes suffer from large surface resistance, and an electrodeless technique is desired. To address this need, an inductive probing scheme, originally developed for shock tube studies, has been adapted. In this method, the perturbation of an applied magnetic field by a plasma jet induces a voltage in a search coil, which, in turn, can be used to infer electrical conductivity through the inversion of a Fredholm integral equation of the first kind. A 1-in.-diameter probe using a light-gas gun. Exploratory laboratory experiments were carried out using plasma jets expelled from 15-g shaped charges. Measured conductivities were in the range of 4 kS/m for unseeded octol charges and 26 kS/m for seeded octol charges containing 2-percent potassium carbonate by mass.

  15. Complex astrophysical experiments relating to jets, solar loops, and water ice dusty plasma

    NASA Astrophysics Data System (ADS)

    Bellan, P. M.; Zhai, X.; Chai, K. B.; Ha, B. N.

    2015-10-01

    > Recent results of three astrophysically relevant experiments at Caltech are summarized. In the first experiment magnetohydrodynamically driven plasma jets simulate astrophysical jets that undergo a kink instability. Lateral acceleration of the kinking jet spawns a Rayleigh-Taylor instability, which in turn spawns a magnetic reconnection. Particle heating and a burst of waves are observed in association with the reconnection. The second experiment uses a slightly different setup to produce an expanding arched plasma loop which is similar to a solar corona loop. It is shown that the plasma in this loop results from jets originating from the electrodes. The possibility of a transition from slow to fast expansion as a result of the expanding loop breaking free of an externally imposed strapping magnetic field is investigated. The third and completely different experiment creates a weakly ionized plasma with liquid nitrogen cooled electrodes. Water vapour injected into this plasma forms water ice grains that in general are ellipsoidal and not spheroidal. The water ice grains can become quite long (up to several hundred microns) and self-organize so that they are evenly spaced and vertically aligned.

  16. Issues and Solutions for Implementation of a Nanoparticle Plasma Jet Diagnostic on DIII-D

    NASA Astrophysics Data System (ADS)

    Thompson, J. R.; Bogatu, I. N.

    2014-10-01

    For ITER, runaway electron (RE) beams are considered a critical problem. Moreover, RE beam dynamics involves processes not yet fully understood or precisely diagnosed. FAR-TECH has proposed using a C60/C plasma jet as a novel diagnostic probe for RE beam-plasma interaction on DIII-D. The existing FAR-TECH prototype plasma jet system is expected to deliver up to ~75 mg C60, at ~4 km/s, and within ~1 ms of triggering, resulting in a free and bound electron density ~2.4 × 1021 m3, about 60 times larger than the typical DIII-D pre-disruption operation value. Implementation of a 100 kJ pulsed power plasma jet system is non-trivial, with electromagnetic interference (EMI) and safety being two major issues. Microsecond timescale, high current drivers generate significant EMI from which other DIII D systems need to be shielded. Safety issues associated with high voltage and potential capacitor failure must also be addressed. We will present the status of our investigation into the principle solutions for the critical issues involved in the implementation of FAR-TECH's prototype C60/C plasma jet system on DIII-D. Work supported by US DOE Grant DE-SC0011864.

  17. Transfer of a cold atmospheric pressure plasma jet through a long flexible plastic tube

    NASA Astrophysics Data System (ADS)

    Kostov, Konstantin G.; Machida, Munemasa; Prysiazhnyi, Vadym; Honda, Roberto Y.

    2015-04-01

    This work proposes an experimental configuration for the generation of a cold atmospheric pressure plasma jet at the downstream end of a long flexible plastic tube. The device consists of a cylindrical dielectric chamber where an insulated metal rod that serves as high-voltage electrode is inserted. The chamber is connected to a long (up to 4 m) commercial flexible plastic tube, equipped with a thin floating Cu wire. The wire penetrates a few mm inside the discharge chamber, passes freely (with no special support) along the plastic tube and terminates a few millimeters before the tube end. The system is flushed with Ar and the dielectric barrier discharge (DBD) is ignited inside the dielectric chamber by a low frequency ac power supply. The gas flow is guided by the plastic tube while the metal wire, when in contact with the plasma inside the DBD reactor, acquires plasma potential. There is no discharge inside the plastic tube, however an Ar plasma jet can be extracted from the downstream tube end. The jet obtained by this method is cold enough to be put in direct contact with human skin without an electric shock. Therefore, by using this approach an Ar plasma jet can be generated at the tip of a long plastic tube far from the high-voltage discharge region, which provides the safe operation conditions and device flexibility required for medical treatment.

  18. Identification of the biologically active liquid chemistry induced by a nonthermal atmospheric pressure plasma jet.

    PubMed

    Wende, Kristian; Williams, Paul; Dalluge, Joe; Gaens, Wouter Van; Aboubakr, Hamada; Bischof, John; von Woedtke, Thomas; Goyal, Sagar M; Weltmann, Klaus-Dieter; Bogaerts, Annemie; Masur, Kai; Bruggeman, Peter J

    2015-01-01

    The mechanism of interaction of cold nonequilibrium plasma jets with mammalian cells in physiologic liquid is reported. The major biological active species produced by an argon RF plasma jet responsible for cell viability reduction are analyzed by experimental results obtained through physical, biological, and chemical diagnostics. This is complemented with chemical kinetics modeling of the plasma source to assess the dominant reactive gas phase species. Different plasma chemistries are obtained by changing the feed gas composition of the cold argon based RF plasma jet from argon, humidified argon (0.27%), to argon/oxygen (1%) and argon/air (1%) at constant power. A minimal consensus physiologic liquid was used, providing isotonic and isohydric conditions and nutrients but is devoid of scavengers or serum constituents. While argon and humidified argon plasma led to the creation of hydrogen peroxide dominated action on the mammalian cells, argon-oxygen and argon-air plasma created a very different biological action and was characterized by trace amounts of hydrogen peroxide only. In particular, for the argon-oxygen (1%), the authors observed a strong negative effect on mammalian cell proliferation and metabolism. This effect was distance dependent and showed a half life time of 30 min in a scavenger free physiologic buffer. Neither catalase and mannitol nor superoxide dismutase could rescue the cell proliferation rate. The strong distance dependency of the effect as well as the low water solubility rules out a major role for ozone and singlet oxygen but suggests a dominant role of atomic oxygen. Experimental results suggest that O reacts with chloride, yielding Cl2(-) or ClO(-). These chlorine species have a limited lifetime under physiologic conditions and therefore show a strong time dependent biological activity. The outcomes are compared with an argon MHz plasma jet (kinpen) to assess the differences between these (at least seemingly) similar plasma sources

  19. Schlieren imaging investigation of the hydrodynamics of atmospheric helium plasma jets

    NASA Astrophysics Data System (ADS)

    Zheng, Yashuang; Wang, Lijun; Ning, Wenjun; Jia, Shenli

    2016-03-01

    This work investigates the hydrodynamic characteristics of a coaxial double-ring electrode helium plasma jet by means of a "Z-type" Schlieren imaging system. The Schlieren images and visual optical photographs made show that a transition point from a laminar region to a turbulent region exists for gas flow without plasma when the helium flow rate exceeds a certain value. After plasma ignition, the laminar region shrinks with voltage increases, and the maximum length of the plasma plume is confined to the laminar region. The heat transfer equation and the spectral broadening of the He I 667.8 nm were used to estimate the increased gas temperature in the plasma jet, and the change in gas velocity by ionic momentum transfer was found by application of a double sphere collision model. As a result, gas heating is considered to be the dominant factor for the earlier onset of turbulence after plasma ignition, whereas the role of ion momentum transfer to neutral gas molecules is comparatively weak. The hydrodynamic behaviors of the plasma jet at the impact region for organic glass and silicon substrates are also researched. The ionization front propagates along the organic glass surface and contracts at the impact point on the silicon surface. More visible vortices are observed from Schlieren images with silicon substrates than with organic glass substrates. Possible mechanisms related to the different treatment effects are discussed.

  20. EDITORIAL: The interaction of radio-frequency fields with fusion plasmas: the JET experience The interaction of radio-frequency fields with fusion plasmas: the JET experience

    NASA Astrophysics Data System (ADS)

    Ongena, Jef

    2012-07-01

    The JET Task Force Heating is proud to present this special issue. It is the result of hard and dedicated work by everybody participating in the Task Force over the last four years and gives an overview of the experimental and theoretical results obtained in the period 2008-2010 with radio frequency heating of JET fusion plasmas. Topics studied and reported in this issue are: investigations into the operation of lower hybrid heating accompanied by new modeling results; new experimental results and insights into the physics of various ion cyclotron range of frequencies (ICRF) heating scenarios; progress in studies of intrinsic and ion cyclotron wave-induced plasma rotation and flows; a summary of the developments over the last years in designing an ion cyclotron radiofrequency heating (ICRH) system that can cope with the presence of fast load variations in the edge, as e.g. caused by pellets or edge localized modes (ELMs) during H-Mode operation; an overview of the results obtained with the ITER-like antenna operating in H-Mode with a packed array of straps and power densities close to those of the projected ITER ICRH antenna; and, finally, a summary of the results obtained in applying ion cyclotron waves for wall conditioning of the tokamak. This issue would not have been possible without the strong motivation and efforts (sometimes truly heroic) of all colleagues of the JET Task Force Heating. A sincere word of thanks, therefore, to all authors and co-authors involved in the experiments, analysis and compilation of the papers. It was a special privilege to work with all of them during the past very intense years. Thanks also to all other European and non-European scientists who contributed to the JET scientific programme, the operations team of JET and the colleagues of the Close Support Unit in Culham. Thanks also to the editors, Editorial Board and referees of Plasma Physics and Controlled Fusion, together with the publishing staff of IOPP, who have not only

  1. Electron properties and air mixing in radio frequency driven argon plasma jets at atmospheric pressure

    SciTech Connect

    Gessel, Bram van; Bruggeman, Peter; Brandenburg, Ronny

    2013-08-05

    A time modulated radio frequency (RF) plasma jet operated with an Ar mixture is investigated by measuring the electron density and electron temperature using Thomson scattering. The measurements have been performed spatially resolved for two different electrode configurations and as a function of the plasma dissipated power and air concentration admixed to the Ar. Time resolved measurements of electron densities and temperatures during the RF cycle and after plasma power switch-off are presented. Furthermore, the influence of the plasma on the air entrainment into the effluent is studied using Raman scattering.

  2. Development of a stable dielectric-barrier discharge enhanced laminar plasma jet generated at atmospheric pressure

    SciTech Connect

    Tang Jie; Li Shibo; Zhao Wei; Wang Yishan; Duan Yixiang

    2012-06-18

    A stable nonthermal laminar atmospheric-pressure plasma source equipped with dielectric-barrier discharge was developed to realize more efficient plasma generation, with the total energy consumption reduced to nearly 25% of the original. Temperature and emission spectra monitoring indicates that this plasma is uniform in the lateral direction of the jet core region. It is also found that this plasma contains not only abundant excited argon atoms but also sufficient excited N{sub 2} and OH. This is mainly resulted from the escape of abundant electrons from the exit, due to the sharp decrease of sustaining voltage and the coupling between ions and electrons.

  3. Influence of geometrical parameters on performance of plasma synthetic jet actuator

    NASA Astrophysics Data System (ADS)

    Zong, Hao-hua; Wu, Yun; Jia, Min; Song, Hui-min; Liang, Hua; Li, Ying-hong; Zhang, Zhi-bo

    2016-01-01

    Plasma synthetic jet actuator (PSJA) has shown wide and promising application prospects in a high speed flow control field, due to its rapid response, high exhaust velocity, and non-moving components. In this paper, the total pressure profile of a plasma synthetic jet (PSJ) is measured and a new method is developed to evaluate the pulsed thrust of the PSJA. The influence of geometrical parameters including the electrode distance, the orifice diameter, and the throat length on PSJA performance is analyzed based on the pulsed thrust, the discharge characteristics, and the schlieren images. When varying the electrode distance, the dominant factor determining the jet intensity is the heating volume instead of the discharge energy. For the arc discharge, the electrode distance should be extended to increase both the jet velocity and the jet duration time. The design of the orifice diameter should be based on the controlled flow field. A large orifice diameter produces a strong perturbation with short time duration, while a small orifice diameter induces a lasting jet with low mass flux. In order to obtain better high frequency performance, the throat length should be shortened on the condition that the structural strength of the PSJA is maintained, while there is almost no influence of the throat length on the single cycle performance of the PSJA. Once the discharge energy is fixed, the pulsed thrust remains almost unchanged with different orifice diameters and throat lengths. These three geometrical parameters are independent to some extent and can be optimized separately.

  4. INSTRUMENTS AND METHODS OF INVESTIGATION: Modification of material properties and coating deposition using plasma jets

    NASA Astrophysics Data System (ADS)

    Pogrebnyak, Alexander D.; Tyurin, Yu N.

    2005-05-01

    The review is concerned with the current status of research on the use of plasma jets for the modification of surface properties of metalware, as well as of investigations of doping and mass transfer of elements. The effect of thermal plasma parameters on the efficiency of surface processing of metal materials is discussed. The structure and properties of protective coatings produced by exposure to pulsed plasmas are analyzed. A new direction for the production of combined coatings is considered. Their structure and properties were studied by the example of Fe, Cu, steels, and alloys, including titanium alloys; the modification process was shown to be controllable by the action of pulsed plasma jets. The physical factors that affect the modification process and the coating deposition, and their effect on the structure and properties of metallic, ceramic - metal, and ceramic coatings were analyzed.

  5. Effect of cold atmospheric pressure He-plasma jet on DNA change and mutation

    NASA Astrophysics Data System (ADS)

    Yaopromsiri, C.; Yu, L. D.; Sarapirom, S.; Thopan, P.; Boonyawan, D.

    2015-12-01

    Cold atmospheric pressure plasma jet (CAPPJ) effect on DNA change was studied for assessment of its safety. The experiment utilized a home-developed CAPPJ using 100% helium to directly treat naked DNA plasmid pGFP (plasmid green fluorescent protein). A traversal electric field was applied to separate the plasma components and both dry and wet sample conditions were adopted to investigate various factor roles in changing DNA. Plasma species were measured by using optical emission spectroscopy. DNA topological form change was analyzed by gel electrophoresis. The plasma jet treated DNA was transferred into bacterial Escherichia coli cells for observing mutation. The results show that the He-CAPPJ could break DNA strands due to actions from charge, radicals and neutrals and potentially cause genetic modification of living cells.

  6. The employment of a high density plasma jet for the investigation of thermal protection materials

    NASA Astrophysics Data System (ADS)

    Kezelis, R.; Grigaitiene, V.; Levinskas, R.; Brinkiene, K.

    2014-05-01

    This paper describes the results of tests of thermal protection materials (TPM) at conditions that simulate the atmospheric re-entry of space vehicles, tested by means of a high velocity and enthalpy air plasma jet generated with a dc plasma torch. Such a high velocity and enthalpy air plasma jet allows us to investigate TPM by simulating heat flux values varying with time in accordance with real re-entry altitudes and trajectories. The main research interests include the measurements of plasma flow temperature and heat flux for the testing of materials used for thermal protection systems of space vehicles. The test results of investigations of light composite thermal protective system material and graphite are presented.

  7. Ion acceleration and plasma jet formation in ultra-thin foils undergoing expansion and relativistic transparency

    NASA Astrophysics Data System (ADS)

    King, M.; Gray, R. J.; Powell, H. W.; MacLellan, D. A.; Gonzalez-Izquierdo, B.; Stockhausen, L. C.; Hicks, G. S.; Dover, N. P.; Rusby, D. R.; Carroll, D. C.; Padda, H.; Torres, R.; Kar, S.; Clarke, R. J.; Musgrave, I. O.; Najmudin, Z.; Borghesi, M.; Neely, D.; McKenna, P.

    2016-09-01

    At sufficiently high laser intensities, the rapid heating to relativistic velocities and resulting decompression of plasma electrons in an ultra-thin target foil can result in the target becoming relativistically transparent to the laser light during the interaction. Ion acceleration in this regime is strongly affected by the transition from an opaque to a relativistically transparent plasma. By spatially resolving the laser-accelerated proton beam at near-normal laser incidence and at an incidence angle of 30°, we identify characteristic features both experimentally and in particle-in-cell simulations which are consistent with the onset of three distinct ion acceleration mechanisms: sheath acceleration; radiation pressure acceleration; and transparency-enhanced acceleration. The latter mechanism occurs late in the interaction and is mediated by the formation of a plasma jet extending into the expanding ion population. The effect of laser incident angle on the plasma jet is explored.

  8. Effect of Pulsed Plasma Jets on the Recovering Boundary Layer Downstream of a Reflected Shock Interaction

    NASA Astrophysics Data System (ADS)

    Greene, Benton; Clemens, Noel; Magari, Patrick; Micka, Daniel; Ueckermann, Mattheus

    2015-11-01

    Shock-induced turbulent boundary layer separation can have many detrimental effects in supersonic inlets including flow distortion and instability, structural fatigue, poor pressure recovery, and unstart. The current study investigates the effect of pulsed plasma jets on the recovering boundary layer downstream of a reflected shock wave-boundary layer interaction. The effects of pitch and skew angle of the jet as well as the heating parameter and discharge time scale are tested using several pulsing frequencies. In addition, the effect of the plasma jets on the undisturbed boundary layer at 6 mm and 11 mm downstream of the jets is measured. A pitot-static pressure probe is used to measure the velocity profile of the boundary layer 35 mm downstream of the plasma jets, and the degree of boundary layer distortion is compared between the different models and run conditions. Additionally, the effect of each actuator configuration on the shape of the mean separated region is investigated using surface oil flow visualization. Previous studies with lower energy showed a weak effect on the downstream boundary layer. The current investigation will attempt to increase this effect using a higher-energy discharge. Funded by AFRL through and SBIR in collaboration with Creare, LLC.

  9. Implosion of an aluminum plasma jet onto a coaxial wire: A Z pinch with enhanced stability and energy transfer

    SciTech Connect

    Wessel, F.J.; Etlicher, B. ); Choi, P. )

    1992-11-30

    We describe {ital Z}-pinch experiments imploding an aluminum-plasma jet onto a coaxial, micron-diameter wire. Spatially resolved x-ray pinhole images and time resolved x-ray data indicate that energy is supplied initially to the aluminum-jet plasma and subsequently transferred to the wire. The resultant pinch appears more uniform (stable) than a wire-only or jet-only pinch and demonstrates that an imploding-plasma liner will couple energy from a pulsed-power generator to a micron-diameter-sized plasma channel.

  10. Jet Tomography of Quark Gluon Plasmas in High Energy Nuclear Collisions

    NASA Astrophysics Data System (ADS)

    Gyulassy, Miklos

    2015-04-01

    The attenuation pattern of high energy jet fragments in ultra-relativistic nuclear collisions provides information on the space-time evolution and dynamical properties of the Quark Gluon Plasma (QGP) phase of matter discovered at the Relativistic Heavy Ion Collider (RHIC) and observed at higher densities at the Large Hadron Collider (LHC). First I review our jet tomography theory of quark and gluon energy loss in a weakly coupled picture of the QGP. While the average attenuation pattern of light and heavy quark jets were well accounted for in that picture, the predicted azimuthal elliptic asymmetry of jets was underestimated when realistic bulk collective flow effects were taken into account. I then show that the elliptic asymmetry of jet fragments can also be quantitatively understood when nonperturbative lattice QCD constraints on the suppression of color electric fluctuations and the enhancement of color magnetic fluctuations near the critical QCD confinement temperature, Tc ~ 160 MeV, are incorporated into the theory. Our analysis provides a novel quantitative connection between the jet transport properties controlling the hard jet quenching observables and the bulk viscous transport properties controlling the remarkable ``perfect fluidity'' of QGP observed at RHIC and LHC.

  11. Entrainment in High-Velocity, High Temperature Plasma Jets Part I: Experimental Results

    SciTech Connect

    Fincke, J.R.; Crawford, D.M.; Snyder, S.C.; Swank, W.D.; Haggard, D.C.; Williamson, R.L.

    2002-03-27

    The development of a high-velocity, high-temperature argon plasma jet issuing into air has been investigated. In particular the entrainment of the surrounding air, its effect on the temperature and velocity profiles and the subsequent mixing and dissociation of oxygen has been examined in detail. The total concentration of oxygen and the velocity and temperature profiles in the jet were obtained from an enthalpy probe. High-resolution Thomson scattering provided an independent measure of plasma velocity and temperature, validating enthalpy probe measurements and providing non-intrusive measurements near the nozzle exit. The concentration of atomic oxygen was obtained from two-photon Laser Induced Fluorescence (LIF). Molecular oxygen concentration and temperature was obtained from Coherent Anti-Stokes Raman Spectroscopy (CARS). It was found that both the incompleteness of mixing at the molecular scale and the rate of oxygen dissociation and recombination effects jet behavior.

  12. Measurement of the energy content of the JET tokamak plasma with a diamagnetic loop

    NASA Astrophysics Data System (ADS)

    Tonetti, G.; Christiansen, J. P.; de Kock, L.

    1986-08-01

    An accurate and reliable measurement of poloidal β is essential to assess the performances of Joint European Torus (JET). The diamagnetic loop can measure β values as low as 0.1 in JET discharges with a plasma current larger than 2×106 A. The instrumentation used includes a flux loop rigidly fitted on a toroidal field (TF) coil, a large Rogowski coil measuring the TF busbar current, and a displacement gauge measuring the TF coil expansion. The fluxes to be compensated originate, in order of importance, from the TF current, the eddy current in the vessel, the TF coil expansion, and the stray coupling with the poloidal fields. The TF and eddy currents must be particularly well compensated on JET since the plasma current starts before the toroidal field has reached its plateau value. Comparison between the diamagnetic and other evaluations of β shows a good agreement.

  13. Measurement of the energy content of the JET tokamak plasma with a diamagnetic loop

    SciTech Connect

    Tonetti, G.; Christiansen, J.P.; de Kock, L.

    1986-08-01

    An accurate and reliable measurement of poloidal ..beta.. is essential to assess the performances of Joint European Torus (JET). The diamagnetic loop can measure ..beta.. values as low as 0.1 in JET discharges with a plasma current larger than 2 x 10/sup 6/ A. The instrumentation used includes a flux loop rigidly fitted on a toroidal field (TF) coil, a large Rogowski coil measuring the TF busbar current, and a displacement gauge measuring the TF coil expansion. The fluxes to be compensated originate, in order of importance, from the TF current, the eddy current in the vessel, the TF coil expansion, and the stray coupling with the poloidal fields. The TF and eddy currents must be particularly well compensated on JET since the plasma current starts before the toroidal field has reached its plateau value. Comparison between the diamagnetic and other evaluations of ..beta.. shows a good agreement.

  14. Surface Decontamination of Chemical Agent Surrogates Using an Atmospheric Pressure Air Flow Plasma Jet

    NASA Astrophysics Data System (ADS)

    Li, Zhanguo; Li, Ying; Cao, Peng; Zhao, Hongjie

    2013-07-01

    An atmospheric pressure dielectric barrier discharge (DBD) plasma jet generator using air flow as the feedstock gas was applied to decontaminate the chemical agent surrogates on the surface of aluminum, stainless steel or iron plate painted with alkyd or PVC. The experimental results of material decontamination show that the residual chemical agent on the material is lower than the permissible value of the National Military Standard of China. In order to test the corrosion effect of the plasma jet on different material surfaces in the decontamination process, corrosion tests for the materials of polymethyl methacrylate, neoprene, polyvinyl chloride (PVC), polyethylene (PE), phenolic resin, iron plate painted with alkyd, stainless steel, aluminum, etc. were carried out, and relevant parameters were examined, including etiolation index, chromatism, loss of gloss, corrosion form, etc. The results show that the plasma jet is slightly corrosive for part of the materials, but their performances are not affected. A portable calculator, computer display, mainboard, circuit board of radiogram, and a hygrometer could work normally after being treated by the plasma jet.

  15. Note: Design and investigation of a multichannel plasma-jet triggered gas switch.

    PubMed

    Tie, Weihao; Liu, Xuandong; Zhang, Qiaogen; Liu, Shanhong

    2014-07-01

    We described the fabrication and testing of a multichannel plasma-jet triggered gas switch (MPJTGS). A novel six-channel annular micro-plasma-gun was embedded in the trigger electrode to generate multichannel plasma jets as a nanosecond trigger pulse arrived. The gas breakdown in multiple sites of the spark gap was induced and fixed around jet orifices by the plasma jets. We tested the multichannel discharge characteristics of the MPJTGS in two working modes with charge voltage of 50 kV, trigger voltage of +40 kV (25 ns rise time), and trigger energy of 240 J, 32 J, and 2 J, respectively, at different working coefficients. Results show that the average number of discharge channels increased as the trigger energy increased, and decreased as the working coefficient decreased. At a working coefficient of 87.1% and trigger energy of 240 J, the average number of discharge channels in Mode II could reach 4.1. PMID:25085190

  16. Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet

    NASA Astrophysics Data System (ADS)

    Bayliss, D. L.; Walsh, J. L.; Shama, G.; Iza, F.; Kong, M. G.

    2009-11-01

    Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium-oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the CAP jet. Outside the light-emitting part of the CAP jet, plasma treatment results in a 'skeleton' of much reduced amyloid stacks with clear evidence of fibril fragmentation. Analysis of possible plasma species and the physical configuration of the jet-sample interaction suggests that the skeleton structures observed are unlikely to have arisen as a result of physical forces of detachment, but instead by progressive diffusion of oxidizing plasma species into porous amyloid aggregates. Composition of chemical bonds of this reduced amyloid sample is very different from that of intact amyloid aggregates. These suggest the possibility of on-site degradation by CAP treatment with little possibility of spreading contamination elsewhere , thus offering a new reaction chemistry route to protein infectivity control with desirable implications for the practical implementation of CAP-based sterilization systems.

  17. Computer-aided simulation and experimental study of dusted plasma jets emitting into limited space

    SciTech Connect

    Borisov, Y.; Chernyshov, A.; Krivtsun, I.; Chizhenko, M.; Shimanovich, V.; Krat`ko, I.

    1994-12-31

    The paper shows peculiarities of particle heating and movement in plasma jets emitting into a limited space: under the higher pressure conditions and in the presence of a protective nozzle expanding the gas-dynamic channel. The computer model has been developed for the above conditions on the basis of the computation-analytical diagram. Measurements are given for the velocity and the radiation spectral characteristics of the dusted plasma jets. It is established, that the intensity of the heat exchange processes increases and the velocity of the plasma jet emission decreases with an increase in the ambient pressure. In the interval from 1 to 4 atm. There occurs the maximum of the intensity of particles heating. When using the protective nozzle the heat exchange processes are improved essentially with an insignificant decrease in the plasma jet velocity due to the higher values of hydraulic resistance of the gas-dynamic channel. The possibility is demonstrated for an increase in the velocity of the sprayed particles by forming an additional peripheral flow at the nozzle end near the surface being sprayed.

  18. Influence of Penning effect on the plasma features in a non-equilibrium atmospheric pressure plasma jet

    SciTech Connect

    Chang, Zhengshi; Zhang, Guanjun; Jiang, Nan; Cao, Zexian

    2014-03-14

    Non-equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises various innovative applications. The influence of Penning effect on the formation, propagation, and other physical properties of the plasma bullets in APPJ remains a debatable topic. By using a 10 cm wide active electrode and a frequency of applied voltage down to 0.5 Hz, the Penning effect caused by preceding discharges can be excluded. It was found that the Penning effect originating in a preceding discharge helps build a conductive channel in the gas flow and provide seed electrons, thus the discharge can be maintained at a low voltage which in turn leads to a smaller propagation speed for the plasma bullet. Photographs from an intensified charge coupled device reveal that the annular structure of the plasma plume for He is irrelevant to the Penning ionization process arising from preceding discharges. By adding NH{sub 3} into Ar to introduce Penning effect, the originally filamentous discharge of Ar can display a rather extensive plasma plume in ambient as He. These results are helpful for the understanding of the behaviors of non-equilibrium APPJs generated under distinct conditions and for the design of plasma jet features, especially the spatial distribution and propagation speed, which are essential for application.

  19. Modelling of plasma generation and thin film deposition by a non-thermal plasma jet at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Sigeneger, F.; Becker, M. M.; Foest, R.; Loffhagen, D.

    2016-09-01

    The gas flow and plasma in a miniaturized non-thermal atmospheric pressure plasma jet for plasma enhanced chemical vapour deposition has been investigated by means of hydrodynamic modelling. The investigation focuses on the interplay between the plasma generation in the active zone where the power is supplied by an rf voltage to the filaments, the transport of active plasma particles due to the gas flow into the effluent, their reactions with the thin film precursor molecules and the transport of precursor fragments towards the substrate. The main features of the spatially two-dimensional model used are given. The results of the numerical modelling show that most active particles of the argon plasma are mainly confined within the active volume in the outer capillary of the plasma jet, with the exception of molecular argon ions which are transported remarkably into the effluent together with slow electrons. A simplified model of the precursor kinetics yields radial profiles of precursor fragment fluxes onto the substrate, which agree qualitatively with the measured profiles of thin films obtained by static film deposition experiments.

  20. Characterization of Wet Air Plasma Jet Powered by Sinusoidal High Voltage and Nanosecond Pulses for Plasma Agricultural Application

    NASA Astrophysics Data System (ADS)

    Takashima, Keisuke; Shimada, Keisuke; Konishi, Hideaki; Kaneko, Toshiro

    2015-09-01

    Not only for the plasma sterilization but also for many of plasma life-science applications, atmospheric pressure plasma devices that allowed us to control its state and reactive species production are deserved to resolve the roles of the chemical species. Influence of the hydroxyl radical and ozone on germination of conidia of a strawberry pathogen is presented. Water addition to air plasma jet significantly improves germination suppression performance, while measured reactive oxygen species (ROS) are reduced. Although the results show a negative correlation between ROS and the germination suppression, this infers the importance of chemical composition generated by plasma. For further control of the plasma product, a plasma jet powered by sinusoidal high voltage and nanosecond pulses is developed and characterized with the voltage-charge Lissajous. Control of breakdown phase and discharge power by pulse-imposed phase is presented. This work is supported by JSPS KAKENHI Grant-in-Aid for Young Scientists (B) Grant Number 15K17480 and Exploratory Research Grant Number 23644199.

  1. Characterizations of atmospheric pressure low temperature plasma jets and their applications

    NASA Astrophysics Data System (ADS)

    Karakas, Erdinc

    2011-12-01

    Atmospheric pressure low temperature plasma jets (APLTPJs) driven by short pulses have recently received great attention because of their potential in biomedical and environmental applications. This potential is due to their user-friendly features, such as low temperature, low risk of arcing, operation at atmospheric pressure, easy handheld operation, and low concentration of ozone generation. Recent experimental observations indicate that an ionization wave exists and propagates along the plasma jet. The plasma jet created by this ionization wave is not a continuous medium but rather consists of a bullet-like-structure known as "Plasma Bullet". More interestingly, these plasma bullets actually have a donut-shaped makeup. The nature of the plasma bullet is especially interesting because it propagates in the ambient air at supersonic velocities without any externally applied electric field. In this dissertation, experimental insights are reported regarding the physical and chemical characteristics of the APLTPJs. The dynamics of the plasma bullet are investigated by means of a high-speed ICCD camera. A plasma bullet propagation model based on the streamer theory is confirmed with adequate explanations. It is also found that a secondary discharge, ignited by the charge accumulation on the dielectric electrode surfaces at the end of the applied voltage, interrupts the plasma bullet propagation due to an opposing current along the ionization channel. The reason for this interesting phenomenon is explained in detail. The plasma bullet comes to an end when the helium mole fraction along the ionization channel, or applied voltage, or both, are less than some critical values. The presence of an inert gas channel in the surrounding air, such as helium or argon, has a critical role in plasma bullet formation and propagation. For this reason, a fluid dynamics study is employed by a commercially available simulation software, COMSOL, based on finite element method. Spatio

  2. Formation of NOx precursors during Chinese pulverized coal pyrolysis in an arc plasma jet

    SciTech Connect

    Wei-ren Bao; Jin-cao Zhang; Fan Li; Li-ping Chang

    2007-08-15

    The formation of NOx precursors (HCN and NH{sub 3}) from the pyrolysis of several Chinese pulverized coals in an arc plasma jet was investigated through both thermodynamic analysis of the C-H-O-N system and experiments. Results of thermodynamic analysis show that the dominant N-containing gaseous species is HCN together with a small amount of ammonia above the temperature of 2000 K. The increase of H content advances the formation of HCN and NH{sub 3}, but the yields of HCN and NH{sub 3} are decreased with a high concentration of O in the system. These results are accordant with the experimental data. The increasing of input power promotes the formation of HCN and NH{sub 3} from coal pyrolysis in an arc plasma jet. Tar-N is not formed during the process. The yield of HCN changes insignificantly with the changing of the residence time of coal particles in the reactor, but that of NH{sub 3} decreases as residence times increase because of the relative instability at high temperature. Adsorption and gasification of CO{sub 2} on the coal surface also can restrain the formation of HCN and NH{sub 3} compare to the results in an Ar plasma jet. Yields of HCN and NH{sub 3} are sensitive to the coal feeding rate, indicating that NOx precursors could interact with the nascent char to form other N-containing species. The formation of HCN and NH{sub 3} during coal pyrolysis in a H{sub 2}/Ar plasma jet are not dependent on coal rank. The N-containing gaseous species is released faster than others in the volatiles during coal pyrolysis in an arc plasma jet, and the final nitrogen content in the char is lower than that in the parent coal, which it is independent of coal type. 16 refs., 9 figs., 1 tab.

  3. DNA damage in oral cancer cells induced by nitrogen atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Han, Xu; Klas, Matej; Liu, Yueying; Stack, M. Sharon; Ptasinska, Sylwia

    2013-09-01

    The nitrogen atmospheric pressure plasma jet (APPJ) has been shown to effectively induce DNA double strand breaks in SCC-25 oral cancer cells. The APPJ source constructed in our laboratory consists of two external electrodes wrapping around a quartz tube and nitrogen as a feed gas and operates based on dielectric barrier gas discharge. Generally, it is more challenging to ignite plasma in N2 atmosphere than in noble gases. However, this design provides additional advantages such as lower costs compared to the noble gases for future clinical operation. Different parameters of the APPJ configuration were tested in order to determine radiation dosage. To explore the effects of delayed damage and cell self-repairing, various incubation times of cells after plasma treatment were also performed. Reactive species generated in plasma jet and in liquid environment are essential to be identified and quantified, with the aim of unfolding the mystery of detailed mechanisms for plasma-induced cell apoptosis. Moreover, from the comparison of plasma treatment effect on normal oral cells OKF6T, an insight to the selectivity for cancer treatment by APPJ can be explored. All of these studies are critical to better understand the damage responses of normal and abnormal cellular systems to plasma radiation, which are useful for the development of advanced plasma therapy for cancer treatment at a later stage.

  4. Cold atmospheric plasma jet-generated RONS and their selective effects on normal and carcinoma cells

    PubMed Central

    Kim, Sun Ja; Chung, T. H.

    2016-01-01

    Cold atmospheric helium plasma jets were fabricated and utilized for plasma–cell interactions. The effect of operating parameters and jet design on the generation of specific reactive oxygen and nitrogen species (RONS) within cells and cellular response were investigated. It was found that plasma treatment induced the overproduction of RONS in various cancer cell lines selectively. The plasma under a relatively low applied voltage induced the detachment of cells, a reduction in cell viability, and apoptosis, while the plasma under higher applied voltage led to cellular necrosis in our case. To determine whether plasma-induced reactive oxygen species (ROS) generation occurs through interfering with mitochondria-related cellular response, we examined the plasma effects on ROS generation in both parental A549 cells and A549 ρ0 cells. It was observed that cancer cells were more susceptible to plasma-induced RONS (especially nitric oxide (NO) and nitrogen dioxide (NO2−) radicals) than normal cells, and consequently, plasma induced apoptotic cell responses mainly in cancer cells. PMID:26838306

  5. A Sub-microsecond Pulsed Plasma Jet for Endodontic Biofilm Disinfection

    NASA Astrophysics Data System (ADS)

    Jiang, Chunqi; Schaudinn, Christoph; Jaramillo, David E.; Gundersen, Martin A.; Costerton, J. William

    A pulsed, tapered cylindrical plasma jet, several centimeter long and <2 mm in diameter, has been generated by a concentric tubular device for root canal disinfection. This plasma dental probe is typically powered with ˜100 ns, 1 kHz, multi-kilovolt electric pulses and filled with 5 SLPM (standard liter per minute) He/(1%)O2 flow. We report here an in vitro study of the antimicrobial effect of the room temperature plasma jet against monolayer Enterococcus faecalis biofilms on bovine dentins. Resultant colony-forming unit counts were associated with changes in bacterial cell morphology observed using scanning electron microscopy (SEM) following the treatment and control. Treatment of dentin discs cultivated with E. faecalis monolayer biofilms with the plasma (average power ≈ 1 W) for 5 min resulted in 92.4% kill (P < 0.0001). Severe disruption of the cell membranes was observed for the plasma treatment group, while the morphology of the cells remained intact for the negative control group. In addition, a pilot ex vivo test was conducted to examine the bactericidal effect of the plasma against saliva-derived biofilms cultivated in human root canals. Conspicuous biofilm disruption and cleared dentinal surfaces were observed in the canal after the plasma treatment for 5 min. We ­conclude that this non-thermal pulsed plasma-based technology is a potential ­alternative or supplement to existing protocols for root canal disinfection.

  6. Risk assessment of the application of a plasma jet in dermatology

    NASA Astrophysics Data System (ADS)

    Lademann, Juergen; Richter, Heike; Alborova, Alena; Humme, Daniel; Patzelt, Alexa; Kramer, Axel; Weltmann, Klaus-Dieter; Hartmann, Bernd; Ottomann, Christian; Fluhr, Joachim W.; Hinz, Peter; Hübner, Georg; Lademann, Olaf

    2009-09-01

    Regardless of the fact that several highly efficient antiseptics are commercially available, the antiseptic treatment of chronic wounds remains a problem. In the past, electrical plasma discharges have been frequently used in biometrical science for disinfection and sterilization of material surfaces. Plasma systems usually have a temperature of several hundred degrees. Recently, it was reported that ``cold'' plasma can be applied onto living tissue. In in vitro studies on cell culture, it could be demonstrated that this new plasma possesses excellent antiseptic properties. We perform a risk assessment concerning the in vivo application of a ``cold'' plasma jet on patients and volunteers. Two potential risk factors, UV radiation and temperature, are evaluated. We show that the UV radiation of the plasma in the used system is an order of magnitude lower than the minimal erythema dose, necessary to produce sunburn on the skin in vivo. Additionally, thermal damage of the tissue by the plasma can be excluded. The results of the risk assessment stimulate the in vivo application of the investigated plasma jet in the treatment of chronic wounds.

  7. Plasma-Jet-Driven Magneto-Inertial Fusion (PJMIF): Physics and Design for a Plasma Liner Formation Experiment

    NASA Astrophysics Data System (ADS)

    Hsu, Scott; Cassibry, Jason; Witherspoon, F. Douglas

    2014-10-01

    Spherically imploding plasma liners are a potential standoff compression driver for magneto-inertial fusion, which is a hybrid of and operates in an intermediate density between those of magnetic and inertial fusion. We propose to use an array of merging supersonic plasma jets to form a spherically imploding plasma liner. The jets are to be formed by pulsed coaxial guns with contoured electrodes that are placed sufficiently far from the location of target compression such that no hardware is repetitively destroyed. As such, the repetition rate can be higher (e.g., 1 Hz) and ultimately the power-plant economics can be more attractive than most other MIF approaches. During the R&D phase, a high experimental shot rate at reasonably low cost (e.g., < 1 k/shot) may be achieved with excellent diagnostic access, thus enabling a rapid learning rate. After some background on PJMIF and its prospects for reactor-relevant energy gain, this poster describes the physics objectives and design of a proposed 60-gun plasma-liner-formation experiment, which will provide experimental data on: (i) scaling of peak liner ram pressure versus initial jet parameters, (ii) liner non-uniformity characterization and control, and (iii) control of liner profiles for eventual gain optimization.

  8. Flow and Noise Control in High Speed and High Reynolds Number Jets Using Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Samimy, M.; Kastner, J.; Kim, J.-H.; Utkin, Y.; Adamovich, I.; Brown, C. A.

    2006-01-01

    The idea of manipulating flow to change its characteristics is over a century old. Manipulating instabilities of a jet to increase its mixing and to reduce its radiated noise started in the 1970s. While the effort has been successful in low-speed and low Reynolds number jets, available actuators capabilities in terms of their amplitude, bandwidth, and phasing have fallen short in control of high-speed and high Reynolds number jets of practical interest. Localized arc filament plasma actuators have recently been developed and extensively used at Gas Dynamics and Turbulence Laboratory (GDTL) for control of highspeed and high Reynolds number jets. While the technique has been quite successful and is very promising, all the work up to this point had been carried out using small high subsonic and low supersonic jets from a 2.54 cm diameter nozzle exit with a Reynolds number of about a million. The preliminary work reported in this paper is a first attempt to evaluate the scalability of the technique. The power supply/plasma generator was designed and built in-house at GDTL to operate 8 actuators simultaneously over a large frequency range (0 to 200 kHz) with independent control over phase and duty cycle of each actuator. This allowed forcing the small jet at GDTL with azimuthal modes m = 0, 1, 2, 3, plus or minus 1, plus or minus 2, and plus or minus 4 over a large range of frequencies. This power supply was taken to and used, with minor modifications, at the NASA Nozzle Acoustic Test Rig (NATR). At NATR, 32 actuators were distributed around the 7.5 in. nozzle (a linear increase with nozzle exit diameter would require 60 actuators). With this arrangement only 8 actuators could operate simultaneously, thus limiting the forcing of the jet at NATR to only three azimuthal modes m = plus or minus 1, 4, and 8. Very preliminary results at NATR indicate that the trends observed in the larger NASA facility in terms of the effects of actuation frequency and azimuthal modes are

  9. Microbial Inactivation in the Liquid Phase Induced by Multigas Plasma Jet

    PubMed Central

    Takamatsu, Toshihiro; Uehara, Kodai; Sasaki, Yota; Hidekazu, Miyahara; Matsumura, Yuriko; Iwasawa, Atsuo; Ito, Norihiko; Kohno, Masahiro; Azuma, Takeshi; Okino, Akitoshi

    2015-01-01

    Various gas atmospheric nonthermal plasmas were generated using a multigas plasma jet to treat microbial suspensions. Results indicated that carbon dioxide and nitrogen plasma had high sterilization effects. Carbon dioxide plasma, which generated the greatest amount of singlet oxygen than other gas plasmas, killed general bacteria and some fungi. On the other hand, nitrogen plasma, which generated the largest amount of OH radical, killed ≥6 log of 11 species of microorganisms, including general bacteria, fungi, acid-fast bacteria, spores, and viruses in 1–15 min. To identify reactive species responsible for bacterial inactivation, antioxidants were added to bacterial suspensions, which revealed that singlet oxygen and OH radicals had greatest inactivation effects. PMID:26173107

  10. TFTR/JET INTOR workshop on plasma transport tokamaks

    SciTech Connect

    Singer, C.E.

    1985-01-01

    This report summarizes the proceedings of a Workshop on transport models for prediction and analysis of tokamak plasma confinement. Summaries of papers on theory, predictive modeling, and data analysis are included.

  11. Two-dimensional profile measurement of plasma parameters in radio frequency-driven argon atmospheric pressure plasma jet

    SciTech Connect

    Seo, B. H.; Kim, J. H.; Kim, D. W.; You, S. J.

    2015-09-15

    The two-dimensional profiles of the electron density, electron temperature, neutral translational temperature, and molecular rotational temperature are investigated in an argon atmospheric pressure plasma jet, which is driven by the radio frequency of 13.56 MHz by means of the laser scattering methods of Thomson, Rayleigh, and Raman. All measured parameters have maximum values at the center of the discharge and decrease toward the plasma edge. The results for the electron temperature profile are contrary to the results for the microwave-driven plasma. From our experimental results, the profiles of the plasma parameters arise from the radial contraction of plasmas and the time averaged profile of the electric field, which is obtained by a microwave simulation performed under identical conditions to the plasma jet. In the case of the neutral temperature, a higher translational temperature than the rotational temperature is measured, and its discrepancy is tentatively explained in terms of the low ion-neutral charge exchange rate and the additional degrees of freedom of the molecules. The description of our experimental results and the underlying physics are addressed in detail.

  12. Particle Acceleration in Collapsing Magnetic Traps with a Braking Plasma Jet

    NASA Astrophysics Data System (ADS)

    Borissov, Alexei; Neukirch, Thomas; Threlfall, James

    2016-05-01

    Collapsing magnetic traps (CMTs) are one proposed mechanism for generating non-thermal particle populations in solar flares. CMTs occur if an initially stretched magnetic field structure relaxes rapidly into a lower-energy configuration, which is believed to happen as a by-product of magnetic reconnection. A similar mechanism for energising particles has also been found to operate in the Earth's magnetotail. One particular feature proposed to be of importance for particle acceleration in the magnetotail is that of a braking plasma jet, i.e. a localised region of strong flow encountering stronger magnetic field which causes the jet to slow down and stop. Such a feature has not been included in previously proposed analytical models of CMTs for solar flares. In this work we incorporate a braking plasma jet into a well studied CMT model for the first time. We present results of test particle calculations in this new CMT model. We observe and characterise new types of particle behaviour caused by the magnetic structure of the jet braking region, which allows electrons to be trapped both in the braking jet region and the loop legs. We compare and contrast the behaviour of particle orbits for various parameter regimes of the underlying trap by examining particle trajectories, energy gains and the frequency with which different types of particle orbit are found for each parameter regime.

  13. Effect of the duty cycle on the spark-plug plasma synthetic jet actuator

    NASA Astrophysics Data System (ADS)

    Seyhan, Mehmet; Erkan Akansu, Yahya; Karakaya, Fuat; Yesildag, Cihan; Akbıyık, Hürrem

    2016-03-01

    A promising novel actuator called Spark-Plug Plasma Synthetic Jet (SPSJ) has been developed in Atmospheric Plasma Research Laboratory at Niğde University. It generates electrothermally high synthetic jet velocity by using high voltage. SPSJ actuator can be utilized to be an active flow control device having some advantages such as no moving parts, low energy consumption and easy to integrate the system. This actuator consists of two main components: semi-surface spark plug (NGK BUHW) as an anode electrode and a cap having an orifice as a cathode electrode. The cap, having a jet exit orifice diameter of 2 mm, has diameter of 4.4 mm and height of 4.65 mm. This study presents the characteristics of SPSJ actuator by using the hot wire anemometer in order to approximately determine jet velocity in quiescent air. Peak velocity as high as 180 m/s was obtained for fe= 100 and duty cycle 50%. The flow visualization indicated that the actuator's jet velocity is enough to penetrate the developed boundary layer.

  14. Particle Acceleration in Collapsing Magnetic Traps with a Braking Plasma Jet

    NASA Astrophysics Data System (ADS)

    Borissov, Alexei; Neukirch, Thomas; Threlfall, James

    2016-06-01

    Collapsing magnetic traps (CMTs) are one proposed mechanism for generating non-thermal particle populations in solar flares. CMTs occur if an initially stretched magnetic field structure relaxes rapidly into a lower-energy configuration, which is believed to happen as a by-product of magnetic reconnection. A similar mechanism for energising particles has also been found to operate in the Earth's magnetotail. One particular feature proposed to be of importance for particle acceleration in the magnetotail is that of a braking plasma jet, i.e. a localised region of strong flow encountering stronger magnetic field which causes the jet to slow down and stop. Such a feature has not been included in previously proposed analytical models of CMTs for solar flares. In this work we incorporate a braking plasma jet into a well studied CMT model for the first time. We present results of test particle calculations in this new CMT model. We observe and characterise new types of particle behaviour caused by the magnetic structure of the jet braking region, which allows electrons to be trapped both in the braking jet region and the loop legs. We compare and contrast the behaviour of particle orbits for various parameter regimes of the underlying trap by examining particle trajectories, energy gains and the frequency with which different types of particle orbit are found for each parameter regime.

  15. Inactivation of Listeria monocytogenes on agar and processed meat surfaces by atmospheric pressure plasma jets.

    PubMed

    Lee, Hyun Jung; Jung, Heesoo; Choe, Wonho; Ham, Jun Sang; Lee, Jun Heon; Jo, Cheorun

    2011-12-01

    An apparatus for generating atmospheric pressure plasma (APP) jet was used to investigate the inactivation of Listeria monocytogenes on the surface of agar plates and slices of cooked chicken breast and ham. He, N₂ (both 7 L/min), and mixtures of each with O₂ (0.07 L/min) were used to produce the plasma jets. After treatment for 2 min with APP jets of He, He + O₂, N₂, or N₂ + O₂, the numbers of L. monocytogenes on agar plates were reduced by 0.87, 4.19, 4.26, and 7.59 log units, respectively. Similar treatments reduced the L. monocytogenes inoculated onto sliced chicken breast and ham by 1.37 to 4.73 and 1.94 to 6.52 log units, respectively, according to the input gas used with the N₂ + O₂ mixture being the most effective. Most APP jets reduced the numbers of aerobic bacteria on the meat surfaces to <10² CFU/g, and the numbers remained below that level of detection after storage at 10 °C for 7 days. The results indicate that APP jets are effective for the inactivation of L. monocytogenes on sliced meats and for prolonging the shelf-life of such foods. PMID:21925030

  16. Experimental study of ? RF plasma jet by optical methods

    NASA Astrophysics Data System (ADS)

    DeBenedictis, S.; Dilecce, G.; Simek, M.; Vigliotti, M.

    1998-11-01

    An 0963-0252/7/4/013/img9 jet stream expanding from a radio-frequency discharge has been investigated by optical emission spectroscopy. The axial and lateral profiles of the expansion glow and the jet axial velocity have been measured by optical methods in order to infer the fluid-dynamic properties of the jet. The position of the shock wave is located at about 5 mm from the nozzle, and the stream velocity achieves a maximum of about 2 Mach in the supersonic region. Optical titration of N atoms and the analysis of emitting excited species 0963-0252/7/4/013/img10 and 0963-0252/7/4/013/img11) have been carried out to monitor the active species in the jet stream and their energy content. The titration of N atoms by NO, injected in the subsonic region, monitored by 0963-0252/7/4/013/img9 first positive 0963-0252/7/4/013/img13 band, 0963-0252/7/4/013/img14 NO 0963-0252/7/4/013/img15 and 0963-0252/7/4/013/img16 continuum emissions, has been examined. This latter emission has been found to give a reasonable estimation of the N density, which is in the range of about (0.1-0.2)% 0963-0252/7/4/013/img9 for a discharge power varying from 50 to 80 W. The 0963-0252/7/4/013/img9 first positive emission, NO 0963-0252/7/4/013/img15 and 0963-0252/7/4/013/img20 bands, instead, are largely affected by the presence of the 0963-0252/7/4/013/img21 metastable and by the high velocity of the N stream. The analysis of 0963-0252/7/4/013/img22 and 0963-0252/7/4/013/img11 vibrational distributions shows the presence of a significant density of the 0963-0252/7/4/013/img21 metastable as well as a non-negligible presence in the expansion of hot electrons. A quasi-one-dimensional fluid-dynamic model of the expansion gives a rough account of the measured location of the shock wave and of the velocity and temperature axial profiles.

  17. Mixing and unmixedness in plasma jets 1: Near-field analysis

    NASA Technical Reports Server (NTRS)

    Ilegbusi, Olusegun J.

    1993-01-01

    The flow characteristics in the near-field of a plasma jet are simulated with a two-fluid model. This model accounts for both gradient-diffusion mixing and uni-directional sifting motion resulting from pressure-gradient-body-force imbalance. This latter mechanism is believed to be responsible for the umixedness observed in plasma jets. The unmixedness is considered to be essentially a Rayleigh-Taylor kind instability. Transport equations are solved for the individual plasma and ambient gas velocities, temperatures and volume fractions. Empirical relations are employed for the interface transfers of mass, momentum and heat. The empirical coefficients are first established by comparison of predictions with available experimental data for shear flows. The model is then applied to an Argon plasma jet ejecting into stagnant air. The predicted results show the significant build-up of unmixed air within the plasma gas, even relatively far downstream of the torch. By adjusting the inlet condition, the model adequately reproduces the experimental data.

  18. Influence of oxygen in atmospheric-pressure argon plasma jet on sterilization of Bacillus atrophaeous spores

    SciTech Connect

    Lim, Jin-Pyo; Uhm, Han S.; Li, Shou-Zhe

    2007-09-15

    A nonequilibrium Ar/O{sub 2} plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56 MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. The decimal reduction time (D values) of the Ar/O{sub 2} plasma jet at an exposure distance of 0.5-1.5 cm ranges from 5 to 57 s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

  19. First steps towards the reaction kinetics of HMDSO in an atmospheric pressure plasma jet in argon

    NASA Astrophysics Data System (ADS)

    Loffhagen, Detlef; Becker, Markus M.; Foest, Rüdiger; Schäfer, Jan; Sigeneger, Florian

    2014-10-01

    Hexamethyldisiloxane (HMDSO) is a silicon-organic compound which is often used as precursor for thin-film deposition by means of plasma polymerization because of its high deposition rate and low toxicity. To improve the physical understanding of the deposition processes, fundamental investigations have been performed to clarify the plasma-chemical reaction pathways of HMDSO and their effect on the composition and structure of the deposited film. The current contribution represents the main primary and secondary plasma-chemical processes and their reaction products in the effluent region of an argon plasma jet at atmospheric pressure. The importance of the different collision processes of electrons and heavy particles are discussed. Results of numerical modelling of the plasma jet and the Ar-HMDSO reaction kinetics indicate that the fragmentation of HMDSO is mainly initiated by collisions with molecular argon ions, while Penning ionization processes play a minor role for the reaction kinetics in the effluent region of the jet. The work has been supported by the German Research Foundation (DFG) under Grant LO 623/3-1.

  20. The production mechanisms of OH radicals in a pulsed direct current plasma jet

    SciTech Connect

    Liu, X. Y.; Pei, X. K.; Lu, X. P.; Liu, D. W.; Ostrikov, K.

    2014-09-15

    The production mechanism of OH radicals in a pulsed DC plasma jet is studied by a two-dimensional (2-D) plasma jet model and a one-dimensional (1-D) discharge model. For the plasma jet in the open air, electron-impact dissociation of H{sub 2}O, electron neutralization of H{sub 2}O{sup +}, as well as dissociation of H{sub 2}O by O(1D) are found to be the main reactions to generate the OH species. The contribution of the dissociation of H{sub 2}O by electron is more than the others. The additions of N{sub 2}, O{sub 2}, air, and H{sub 2}O into the working gas increase the OH density outside the tube slightly, which is attributed to more electrons produced by Penning ionization. On the other hand, the additions of O{sub 2} and H{sub 2}O into the working gas increase the OH density inside the tube substantially, which is attributed to the increased O (1D) and H{sub 2}O concentration, respectively. The gas flow will transport high density OH out of the tube during pulse off period. It is also shown that the plasma chemistry and reactivity can be effectively controlled by the pulse numbers. These results are supported by the laser induced fluorescence measurements and are relevant to several applications of atmospheric-pressure plasmas in health care, medicine, and materials processing.

  1. First Production of C60 Nanoparticle Plasma Jet for Study of Disruption Mitigation for ITER

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Thompson, J. R.; Galkin, S. A.; Kim, J. S.; Brockington, S.; Case, A.; Messer, S. J.; Witherspoon, F. D.

    2012-10-01

    Unique fast response and large mass-velocity delivery of nanoparticle plasma jets (NPPJs) provide a novel application for ITER disruption mitigation, runaway electrons diagnostics and deep fueling. NPPJs carry a much larger mass than usual gases. An electromagnetic plasma gun provides a very high injection velocity (many km/s). NPPJ has much higher ram pressure than any standard gas injection method and penetrates the tokamak confining magnetic field. Assimilation is enhanced due to the NP large surface-to-volume ratio. Radially expanding NPPJs help achieving toroidal uniformity of radiation power. FAR-TECH's NPPJ system was successfully tested: a coaxial plasma gun prototype (˜35 cm length, 96 kJ energy) using a solid state TiH2/C60 pulsed power cartridge injector produced a hyper-velocity (>4 km/s), high-density (>10^23 m-3), C60 plasma jet in ˜0.5 ms, with ˜1-2 ms overall response-delivery time. We present the TiH2/C60 cartridge injector output characterization (˜180 mg of sublimated C60 gas) and first production results of a high momentum C60 plasma jet (˜0.6 g.km/s).

  2. Atmospheric-pressure plasma jet characterization and applications on melanoma cancer treatment (B/16-F10)

    SciTech Connect

    Mashayekh, Shahriar; Rajaee, Hajar; Hassan, Zuhir M.; Akhlaghi, Morteza; Shokri, Babak

    2015-09-15

    A new approach in medicine is the use of cold plasma for various applications such as sterilization blood coagulation and cancer cell treatment. In this paper, a pin-to-hole plasma jet for biological applications has been designed and manufactured and characterized. The characterization includes power consumption via Lissajous method, thermal behavior of atmospheric-pressure plasma jet by using Infra-red camera as a novel method and using Speicair software to determine vibrational and transitional temperatures, and optical emission spectroscopy to determine the generated species. Treatment of Melanoma cancer cells (B16/F10) was also implemented, and tetrazolium salt dye (MTT assay) and flow cytometry were used to evaluate viability. Effect of ultraviolet photons on cancerous cells was also observed using an MgF{sub 2} crystal with MTT assay. Finally, in-vivo studies on C57 type mice were also done in order to have a better understanding of the effects in real conditions.

  3. Experimental demonstration of Martian soil simulant removal from a surface using a pulsed plasma jet

    NASA Astrophysics Data System (ADS)

    Ticoş, C. M.; Scurtu, A.; Toader, D.; Banu, N.

    2015-03-01

    A plasma jet produced in a small coaxial plasma gun operated at voltages up to 2 kV and working in pure carbon dioxide (CO2) at a few Torr is used to remove Martian soil simulant from a surface. A capacitor with 0.5 mF is charged up from a high voltage source and supplies the power to the coaxial electrodes. The muzzle of the coaxial plasma gun is placed at a few millimeters near the dusty surface and the jet is fired parallel with the surface. Removal of dust is imaged in real time with a high speed camera. Mars regolith simulant JSC-Mars-1A with particle sizes up to 5 mm is used on different types of surfaces made of aluminium, cotton fabric, polyethylene, cardboard, and phenolic.

  4. Experimental demonstration of Martian soil simulant removal from a surface using a pulsed plasma jet.

    PubMed

    Ticoş, C M; Scurtu, A; Toader, D; Banu, N

    2015-03-01

    A plasma jet produced in a small coaxial plasma gun operated at voltages up to 2 kV and working in pure carbon dioxide (CO2) at a few Torr is used to remove Martian soil simulant from a surface. A capacitor with 0.5 mF is charged up from a high voltage source and supplies the power to the coaxial electrodes. The muzzle of the coaxial plasma gun is placed at a few millimeters near the dusty surface and the jet is fired parallel with the surface. Removal of dust is imaged in real time with a high speed camera. Mars regolith simulant JSC-Mars-1A with particle sizes up to 5 mm is used on different types of surfaces made of aluminium, cotton fabric, polyethylene, cardboard, and phenolic. PMID:25832231

  5. Atmospheric-pressure plasma jet characterization and applications on melanoma cancer treatment (B/16-F10)

    NASA Astrophysics Data System (ADS)

    Mashayekh, Shahriar; Rajaee, Hajar; Akhlaghi, Morteza; Shokri, Babak; Hassan, Zuhir M.

    2015-09-01

    A new approach in medicine is the use of cold plasma for various applications such as sterilization blood coagulation and cancer cell treatment. In this paper, a pin-to-hole plasma jet for biological applications has been designed and manufactured and characterized. The characterization includes power consumption via Lissajous method, thermal behavior of atmospheric-pressure plasma jet by using Infra-red camera as a novel method and using Speicair software to determine vibrational and transitional temperatures, and optical emission spectroscopy to determine the generated species. Treatment of Melanoma cancer cells (B16/F10) was also implemented, and tetrazolium salt dye (MTT assay) and flow cytometry were used to evaluate viability. Effect of ultraviolet photons on cancerous cells was also observed using an MgF2 crystal with MTT assay. Finally, in-vivo studies on C57 type mice were also done in order to have a better understanding of the effects in real conditions.

  6. Numerical simulation of spontaneous magnetic fields in laser produced plasma jets using MAG code

    SciTech Connect

    Diyankov, O. V.; Glazyrin, I. V.; Koshelev, S. V.; Lykov, V. A.

    1997-04-15

    The results of numerical simulation of spontaneous magnetic field generation and influence of this field on laser produced plasma jet expansion in vacuum and low density gas are presented. The numerical simulation has been carried out using MAG code for the case of aluminum plate of 5 {mu}m of thickness irradiated by Nd laser. The laser pulse duration was 0.5 nsec at half-width, laser irradiation intensity was up to 10{sup 13} W/cm{sup 2} and laser focal spot diameter was about 100 {mu}m. According to the received results, the magnetic field amplitude achieves the value of 150 kGs. This fact has no considerable influence on the temperature maximum in laser produced plasma, but significantly affects the process of the energy transport from plasma jet to low density gas.

  7. Modelling of OH production in cold atmospheric-pressure He-H2O plasma jets

    NASA Astrophysics Data System (ADS)

    Naidis, G. V.

    2013-06-01

    Results of the modelling of OH production in the plasma bullet mode of cold atmospheric-pressure He-H2O plasma jets are presented. It is shown that the dominant source of OH molecules is related to the Penning and charge transfer reactions of H2O molecules with excited and charged helium species produced by guided streamers (plasma bullets), in contrast to the case of He-H2O glow discharges where OH production is mainly due to the dissociation of H2O molecules by electron impact.

  8. DNA damage in oral cancer cells induced by nitrogen atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Han, Xu; Klas, Matej; Liu, Yueying; Sharon Stack, M.; Ptasinska, Sylwia

    2013-06-01

    The nitrogen atmospheric pressure plasma jet (APPJ) was applied to induce DNA damage of SCC-25 oral cancer cells. Optical emission spectra were taken to characterize the reactive species produced in APPJ. In order to explore the spatial distribution of plasma effects, cells were placed onto photo-etched grid slides and the antibody H2A.X was used to locate double strand breaks of DNA inside nuclei using an immunofluorescence assay. The number of cells with double strand breaks in DNA was observed to be varied due to the distance from the irradiation center and duration of plasma treatment.

  9. DNA damage in oral cancer cells induced by nitrogen atmospheric pressure plasma jets

    SciTech Connect

    Han, Xu; Ptasinska, Sylwia; Klas, Matej; Liu, Yueying; Sharon Stack, M.

    2013-06-10

    The nitrogen atmospheric pressure plasma jet (APPJ) was applied to induce DNA damage of SCC-25 oral cancer cells. Optical emission spectra were taken to characterize the reactive species produced in APPJ. In order to explore the spatial distribution of plasma effects, cells were placed onto photo-etched grid slides and the antibody H2A.X was used to locate double strand breaks of DNA inside nuclei using an immunofluorescence assay. The number of cells with double strand breaks in DNA was observed to be varied due to the distance from the irradiation center and duration of plasma treatment.

  10. On the design and characterization of a new cold atmospheric pressure plasma jet and its applications on cancer cells treatment.

    PubMed

    Akhlaghi, Morteza; Rajayi, Hajar; Mashayekh, Amir Shahriar; Khani, Mohammadreza; Hassan, Zuhair Mohammad; Shokri, Babak

    2015-01-01

    In this paper, a new configuration of a cold atmospheric pressure plasma jet has been designed and constructed. Poly-methyl-methacrylate was used as a new dielectric in this configuration which in comparison to other dielectrics is inexpensive, more resistant against break, and also more shapeable. Then, the plasma jet parameters such as plume temperature, rotational and vibrational temperatures, power, electrical behavior (voltage and current profile), electron density, and the produced reactive species were characterized. In order to determine the jet temperature and the amount of reactive species, effects of applied voltage, gas flow rate, and distance from the nozzle were studied. The power of the jet was specified using Lissajous curve approach. The plume temperature of the plasma jet was about the room temperature. Optical emission spectroscopy determined the type of reactive species, and also electron density and its corresponding plasma frequency (~6.4 × 10(13) cm(-3) and 4.52 × 10(11) Hz). Because of producing different reactive species, the device can be used in different applications, especially in plasma medicine. Thus, 4T1 cancer cells were treated using this plasma jet. The results showed that this plasma jet has a great potential to kill one of the most aggressive and resistant cancerous cell lines. PMID:25908593

  11. Perturbative and nonperturbative aspects of jet quenching in near-critical quark-gluon plasmas

    NASA Astrophysics Data System (ADS)

    Xu, Jiechen

    In this thesis, we construct two QCD based energy loss models to perform quantitative analysis of jet quenching observables in ultra-relativistic nucleus-nucleus collisions at RHIC and the LHC. We first build up a perturbative QCD based CUJET2.0 jet flavor tomography model that couples the dynamical running coupling DGLV opacity series to bulk data constrained relativistic viscous hydrodynamic backgrounds. It solves the strong heavy quark energy loss puzzle at RHIC and explains the surprising transparency of the quark-gluon plasma (QGP) at the LHC. The observed azimuthal anisotropy of hard leading hadrons requires a path dependent jet-medium coupling in CUJET2.0 that implies physics of nonperturbative origin. To explore the nonperturbative chromo-electric and chromo-magnetic structure of the strongly-coupled QGP through jet probes, we build up a new CUJET3.0 framework that includes in CUJET2.0 both Polyakov loop suppressed semi-QGP chromo-electric charges and emergent chromo-magnetic monopoles in the critical transition regime. CUJET3.0 quantitatively describes the anisotropic hadron suppression at RHIC and the LHC. More significantly, it provides a robust connection between the long wavelength ``perfect fluidity'' of the QGP and the short distance jet transport in the QGP. This framework paves the way for ``measuring'' both perturbative and nonperturbative properties of the QGP, and more importantly for probing color confinement through jet quenching.

  12. Gas and heat dynamics of a micro-scaled atmospheric pressure plasma reference jet

    NASA Astrophysics Data System (ADS)

    Kelly, Seán; Golda, Judith; Turner, Miles M.; Schulz-von der Gathen, Volker

    2015-11-01

    Gas and heat dynamics of the ‘Cooperation on Science and Technology (COST) Reference Microplasma Jet’ (COST-jet), a European lead reference device for low temperature atmospheric pressure plasma application, are investigated. Of particular interest to many biomedical application scenarios, the temperature characteristics of a surface impacted by the jet are revealed. Schlieren imaging, thermocouple measurements, infrared thermal imaging and numerical modelling are employed. Temperature spatial profiles in the gas domain reveal heating primarily of the helium fraction of the gas mixture. Thermocouple and model temporal data show a bounded exponential temperature growth described by a single characteristic time parameter to reach  ∼63% or (1-1/e) fraction of the temperature increase. Peak temperatures occurred in the gas domain where the carrier jet exits the COST-jet, with values ranging from ambient temperatures to in excess of 100 °C in ‘α-mode’ operation. In a horizontal orientation of the COST-jet a curved trajectory of the helium effluent at low gas flows results from buoyant forces. Gas mixture profiles reveal significant containment of the helium concentrations for a surface placed in close proximity to the COST-jet. Surface heating of a quartz plate follows a similar bounded exponential temporal temperature growth as device heating. Spatial profiles of surface heating are found to correlate strongly to the impacting effluent where peak temperatures occur in regions of maximum surface helium concentration.

  13. Two-fluid electromagnetic simulations of plasma-jet acceleration with detailed equation-of-state

    SciTech Connect

    Thoma, C.; Welch, D. R.; Clark, R. E.; Bruner, N.; MacFarlane, J. J.; Golovkin, I. E.

    2011-10-15

    We describe a new particle-based two-fluid fully electromagnetic algorithm suitable for modeling high density (n{sub i} {approx} 10{sup 17} cm{sup -3}) and high Mach number laboratory plasma jets. In this parameter regime, traditional particle-in-cell (PIC) techniques are challenging due to electron timescale and lengthscale constraints. In this new approach, an implicit field solve allows the use of large timesteps while an Eulerian particle remap procedure allows simulations to be run with very few particles per cell. Hall physics and charge separation effects are included self-consistently. A detailed equation of state (EOS) model is used to evolve the ion charge state and introduce non-ideal gas behavior. Electron cooling due to radiation emission is included in the model as well. We demonstrate the use of these new algorithms in 1D and 2D Cartesian simulations of railgun (parallel plate) jet accelerators using He and Ar gases. The inclusion of EOS and radiation physics reduces the electron temperature, resulting in higher calculated jet Mach numbers in the simulations. We also introduce a surface physics model for jet accelerators in which a frictional drag along the walls leads to axial spreading of the emerging jet. The simulations demonstrate that high Mach number jets can be produced by railgun accelerators for a variety of applications, including high energy density physics experiments.

  14. Multi-chord fiber-coupled interferometry of supersonic plasma jets andcomparisons with synthetic data

    SciTech Connect

    Merritt, Elizabeth C.; Lynn, Alan G.; Gilmore, Mark A.; Thoma, Carsten; Loverich, John; Hsu, Scott C.

    2012-05-03

    A multi-chord fiber-coupled interferometer [Merritt et al., Rev. Sci. Instrum. 83, 033506 (2012)] is being used to make time-resolved density measurements of supersonic argon plasma jets on the Plasma Liner Experiment [Hsu et al., Bull. Amer. Phys. Soc. 56, 307 (2011)]. The long coherence length of the laser (> 10 m) allows signal and reference path lengths to be mismatched by many meters without signal degradation, making for a greatly simplified optical layout. Measured interferometry phase shifts are consistent with a partially ionized plasma in which an initially positive phase shift becomes negative when the ionization fraction drops below a certain threshold. In this case, both free electrons and bound electrons in ions and neutral atoms contribute to the index of refraction. This paper illustrates how the interferometry data, aided by numerical modeling, are used to derive total jet density, jet propagation velocity ({approx} 15-50 km/s), jet length ({approx} 20-100 cm), and 3D expansion.

  15. Effect of plasma jet diameter on the efficiency of reactive oxygen and nitrogen species generation in water

    NASA Astrophysics Data System (ADS)

    Oh, Jun-Seok; Kakuta, Maito; Furuta, Hiroshi; Akatsuka, Hiroshi; Hatta, Akimitsu

    2016-06-01

    The plasma jet generation of reactive oxygen and nitrogen species (RONS) in solution is important in biology, medicine, and disinfection. Studies using a wide variety of plasma jet devices have been carried out for this purpose, making it difficult to compare the performance between devices. In this study, we compared the efficiency of RONS generation in deionized (DI) water between 3.7-mm- and 800-µm-sized helium (He) plasma jets (hereafter mm-jet and µm-jet, respectively) at different treatment distances and times. The efficiency of RONS generation was determined by considering the total amount of RONS generated in DI water with respect to the input energy and gas consumption. We found that the mm-jet generated 20% more RONS in the DI water than the µm-jet at the optimized distance. However, when the input power and He gas consumption were taken into account, we discovered that the µm-jet was 5 times more efficient in generating RONS in the DI water. Under the parameters investigated in this study, the concentration of RONS continued to increase as a function of treatment time (up to 30 min). However treatment distance had a marked effect on the efficiency of RONS generation: treatment distances of 25 and 30 mm were optimal for the mm-jet and µm-jet, respectively. Our method of comparing the efficiency of RONS generation in solution between plasma jets could be used as a reference protocol for the development of efficient plasma jet sources for use in medicine, biology, and agriculture.

  16. Laser-driven plasma jets propagating in an ambient gas studied with optical and proton diagnostics

    NASA Astrophysics Data System (ADS)

    Gregory, C. D.; Loupias, B.; Waugh, J.; Dono, S.; Bouquet, S.; Falize, E.; Kuramitsu, Y.; Michaut, C.; Nazarov, W.; Pikuz, S. A.; Sakawa, Y.; Woolsey, N. C.; Koenig, M.

    2010-05-01

    The results of an experiment to propagate laser-generated plasma jets into an ambient medium are presented. The jets are generated via laser irradiation of a foam-filled cone target, the results and characterization of which have been reported previously [Loupias et al., Phys. Rev. Lett. 99, 265001 (2007)] for propagation in vacuum. The introduction of an ambient medium of argon at varying density is seen to result in the formation of a shock wave, and the shock front displays perturbations that appear to grow with time. The system is diagnosed with the aid of proton radiography, imaging the perturbed structure in the dense parts of the shock with high resolution.

  17. Statistical comparison of ICRF and NBI heating performance in JET-ILW L-mode plasmas

    SciTech Connect

    Lerche, E.; Van Eester, D.; Jacquet, Ph.; Mayoral, M.-L.; Graham, M.; Matthews, G.; Monakhov, I.; Rimini, F.; Colas, L.; Czarnecka, A.; Vries, P. de; Collaboration: JET-EFDA Contributors

    2014-02-12

    After the change over from the C-wall to the ITER-like Be/W wall (ILW) in JET, the radiation losses during ICRF heating have increased and are now substantially larger than those observed with NBI at the same power levels, in spite of the similar global plasma energies reached with the two heating systems. A comparison of the NBI and ICRF performances in the JET-ILW experiments, based on a statistical analysis of ∼3000 L-mode discharges, will be presented.

  18. Development and characterization of very dense submillimetric gas jets for laser-plasma interaction

    SciTech Connect

    Sylla, F.; Kahaly, S.; Flacco, A.; Malka, V.; Veltcheva, M.

    2012-03-15

    We report on the characterization of recently developed submillimetric He gas jets with peak density higher than 10{sup 21} atoms/cm{sup 3} from cylindrical and slightly conical nozzles of throat diameter of less than 400 {mu}m. Helium gas at pressure 300-400 bar has been developed for this purpose to compensate the nozzle throat diameter reduction that affects the output mass flow rate. The fast-switching electro-valve enables to operate the jet safely for multi-stage vacuum pump assembly. Such gaseous thin targets are particularly suitable for laser-plasma interaction studies in the unexplored near-critical regime.

  19. Development and characterization of very dense submillimetric gas jets for laser-plasma interaction.

    PubMed

    Sylla, F; Veltcheva, M; Kahaly, S; Flacco, A; Malka, V

    2012-03-01

    We report on the characterization of recently developed submillimetric He gas jets with peak density higher than 10(21) atoms/cm(3) from cylindrical and slightly conical nozzles of throat diameter of less than 400 μm. Helium gas at pressure 300-400 bar has been developed for this purpose to compensate the nozzle throat diameter reduction that affects the output mass flow rate. The fast-switching electro-valve enables to operate the jet safely for multi-stage vacuum pump assembly. Such gaseous thin targets are particularly suitable for laser-plasma interaction studies in the unexplored near-critical regime. PMID:22462922

  20. Risk assessment of a cold argon plasma jet in respect to its mutagenicity.

    PubMed

    Wende, K; Bekeschus, S; Schmidt, A; Jatsch, L; Hasse, S; Weltmann, K D; Masur, K; von Woedtke, T

    2016-03-01

    Cold atmospheric pressure plasmas represent a favorable option for the treatment of heat sensitive materials and human or animal tissue. Beneficial effects have been documented in a variety of medical conditions, e.g., in the treatment of chronic wounds. It is assumed that the main mechanism of the plasma's efficacy is mediated by a stimulating dissipation of energy via radiation and/or chemical energy. Although no evidence on undesired side effects of a plasma treatment has yet been presented, skepticism toward the safety of the exposure to plasma is present. However, only little data regarding the mutagenic potential of this new treatment option is available. Accordingly, we investigated the mutagenic potential of an argon plasma jet (kinpen) using different testing systems in accordance with ISO norms and multiple cell lines: a HPRT1 mutation assay, a micronucleus formation assay, and a colony formation assay. Moderate plasma treatment up to 180 s did not increase genotoxicity in any assay or cell type investigated. We conclude that treatment with the argon plasma jet kinpen did not display a mutagenic potential under the test conditions applied and may from this perspective be regarded as safe for the use in biomedical applications. PMID:26994493

  1. Design and characterization of an RF excited micro atmospheric pressure plasma jet for reference in plasma medicine

    NASA Astrophysics Data System (ADS)

    Schulz-von der Gathen, Volker

    2015-09-01

    Over the last decade a huge variety of atmospheric pressure plasma jets has been developed and applied for plasma medicine. The efficiency of these non-equilibrium plasmas for biological application is based on the generated amounts of reactive species and radiation. The gas temperatures stay within a range tolerable for temperature-sensitive tissues. The variety of different discharge geometries complicates a direct comparison. In addition, in plasma-medicine the combination of plasma with reactive components, ambient air, as well as biologic tissue - typically also incorporating fluids - results in a complex system. Thus, real progress in plasma-medicine requires a profound knowledge of species, their fluxes and processes hitting biological tissues. That will allow in particular the necessary tailoring of the discharge to fit the conditions. The complexity of the problem can only be overcome by a common effort of many groups and requires a comparison of their results. A reference device based on the already well-investigated micro-scaled atmospheric pressure plasma jet is presented. It is developed in the frame of the European COST initiative MP1101 to establish a publicly available, stable and reproducible source, where required plasma conditions can be investigated. Here we present the design and the ideas behind. The presentation discusses the requirements for the reference source and operation conditions. Biological references are also defined by the initiative. A specific part of the talk will be attributed to the reproducibility of results from various samples of the device. Funding by the DFG within the Package Project PAK816 ``Plasma Cell Interaction in Dermatology'' and the Research Unit FOR 1123 ``Physics of microplasmas'' is gratefully acknowledged.

  2. Temporal and spatial resolved optical emission behaviors of a cold atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Xiong, Q.; Lu, X.; Liu, J.; Xian, Y.; Xiong, Z.; Zou, F.; Zou, C.; Gong, W.; Hu, J.; Chen, K.; Pei, X.; Jiang, Z.; Pan, Y.

    2009-10-01

    The propagation behavior of cold atmospheric pressure plasma jets has recently attracted lots of attention. In this paper, a cold He plasma jet generated by a single plasma electrode jet device is studied. The spatial-temporal resolved optical emission spectroscopy measurements are presented. It is found that the emission intensity of the He 706.5 nm line of the plasma behaves similarly both inside the syringe and in the surrounding air (plasma plume). It decreases monotonously, which is different from the emission lines, such as N2 337.1 nm line, N2+ 391.4 nm line, and O 777.3 nm line. For the discharge inside the syringe, the emission intensity of the He 706.5 nm line decays more rapidly than that of the other three spectral lines mentioned above. The N2 337.1 nm line behaves a similar time evolution with the discharge current. For the N2+ 391.4 nm line and the atomic O 777.3 nm line, both of them decay slower than that of the He 706.5 nm and the N2 337.1 nm. When the plasma plume propagates further away from the nozzle, the temporal behaviors of the emission intensities of the four lines tend to be similar gradually. Besides, it is found that, when the size of the plasma bullet appears biggest, the propagation velocity of the bullet achieves its highest value while the emission intensity of the N2+ 391.4 nm line reaches its maximum. Detailed analysis shows that the Penning effect between the metastable state Hem and the air molecules may play a significant role in the propagation of the plasma bullet in the open air.

  3. Measurement of plasma-generated RONS in the cancer cells exposed by atmospheric pressure helium plasma jet

    NASA Astrophysics Data System (ADS)

    Joh, Hea Min; Baek, Eun Jeong; Kim, Sun Ja; Chung, Tae Hun

    2015-09-01

    The plasma-induced reactive oxygen and nitrogen species (RONS) could result in cellular responses including DNA damages and apoptotic cell death. These chemical species, O, O2-,OH, NO, and NO2-,exhibit strong oxidative stress and/or trigger signaling pathways in biological cells. Each plasma-generated chemical species having biological implication should be identified and quantitatively measured. For quantitative measurement of RONS, this study is divided into three stages; plasma diagnostics, plasma-liquid interactions, plasma-liquid-cell interactions. First, the optical characteristics of the discharges were obtained by optical emission spectroscopy to identify various excited plasma species. And the characteristics of voltage-current waveforms, gas temperature, and plume length with varying control parameters were measured. Next, atmospheric pressure plasma jet was applied on the liquid. The estimated OH radical densities were obtained by ultraviolet absorption spectroscopy at the liquid surface. And NO2-is detected by Griess test and compared between the pure liquid and the cell-containing liquid. Finally, bio-assays were performed on plasma treated human lung cancer cells (A549). Intracellular ROS production was measured using DCF-DA. Among these RONS, productions of NO and OH within cells were measured by DAF-2DA and APF, respectively. The data are very suggestive that there is a strong correlation among the production of RONS in the plasmas, liquids, and cells.

  4. Full jet evolution in quark-gluon plasma and nuclear modification of jet production and jet shape in Pb+Pb collisions at 2.76 A TeV at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Chang, Ning-Bo; Qin, Guang-You

    2016-08-01

    We study the evolution of the full jet shower in quark-gluon plasma by solving a set of coupled differential transport equations for the three-dimensional momentum distributions of quarks and gluons contained in full jets. In our jet evolution equations, we include all partonic splitting processes as well as the collisional energy loss and transverse momentum broadening for both the leading and radiated partons of the full jets. Combining with a realistic (2 +1 )-dimensional viscous hydrodynamic simulation for the spacetime profiles of the hot and dense nuclear medium produced in heavy-ion collisions, we apply our formalism to calculate the nuclear modification of single inclusive full jet spectra, the momentum imbalance of photon-jet and dijet pairs, and the jet shape function (at partonic level) in Pb+Pb collisions at 2.76 A TeV. The roles of various jet-medium interaction mechanisms on the full jet modification are studied. We find that the nuclear modification of jet shape is sensitive to the interplay of different interaction mechanisms as well as the energies of the full jets.

  5. Shock formation in supersonic cluster jets and its effect on axially modulated laser-produced plasma waveguides.

    PubMed

    Yoon, S J; Goers, A J; Hine, G A; Magill, J D; Elle, J A; Chen, Y-H; Milchberg, H M

    2013-07-01

    We examine the generation of axially modulated plasmas produced from cluster jets whose supersonic flow is intersected by thin wires. Such plasmas have application to modulated plasma waveguides. By appropriately limiting shock waves from the wires, plasma axial modulation periods can be as small as 70 μm, with plasma structures as narrow as 45 µm. The effect of shocks is eliminated with increased cluster size accompanied by a reduced monomer component of the flow. PMID:23842374

  6. Divertor plasma conditions and neutral dynamics in horizontal and vertical divertor configurations in JET-ILW low confinement mode plasmas

    NASA Astrophysics Data System (ADS)

    Groth, M.; Brezinsek, S.; Belo, P.; Brix, M.; Calabro, G.; Chankin, A.; Clever, M.; Coenen, J. W.; Corrigan, G.; Drewelow, P.; Guillemaut, C.; Harting, D.; Huber, A.; Jachmich, S.; Järvinen, A.; Kruezi, U.; Lawson, K. D.; Lehnen, M.; Maggi, C. F.; Marchetto, C.; Marsen, S.; Maviglia, F.; Meigs, A. G.; Moulton, D.; Silva, C.; Stamp, M. F.; Wiesen, S.

    2015-08-01

    Measurements of the plasma conditions at the low field side target plate in JET ITER-like wall ohmic and low confinement mode plasmas show minor differences in divertor plasma configurations with horizontally and vertically inclined targets. Both the reduction of the electron temperature in the vicinity of the strike points and the rollover of the ion current to the plates follow the same functional dependence on the density at the low field side midplane. Configurations with vertically inclined target plates, however, produce twice as high sub-divertor pressures for the same upstream density. Simulations with the EDGE2D-EIRENE code package predict significantly lower plasma temperatures at the low field side target in vertical than in horizontal target configurations. Including cross-field drifts and imposing a pumping by-pass leak at the low-field side plate can still not recover the experimental observations.

  7. Radial Profiles of the Plasma Electron Characteristics in a 30 kW Arc Jet

    NASA Technical Reports Server (NTRS)

    Codron, Douglas A.; Nawaz, Anuscheh

    2013-01-01

    The present effort aims to strengthen modeling work conducted at the NASA Ames Research Center by measuring the critical plasma electron characteristics within and slightly outside of an arc jet plasma column. These characteristics are intended to give physical insights while assisting in the formulation of boundary conditions to validate full scale simulations. Single and triple Langmuir probes have been used to achieve estimates of the electron temperature (T(sub e)), electron number density (n(sub e)) and plasma potential (outside of the plasma column) as probing location is varied radially from the flow centerline. Both the electron temperature and electron number density measurements show a large dependence on radial distance from the plasma column centerline with T(sub e) approx. = (3 - 12 eV and n(sub e) approx. = 10(exp 12) - 10(exp 14)/cu cm.

  8. Inactivation of Gram-positive biofilms by low-temperature plasma jet at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Marchal, F.; Robert, H.; Merbahi, N.; Fontagné-Faucher, C.; Yousfi, M.; Romain, C. E.; Eichwald, O.; Rondel, C.; Gabriel, B.

    2012-08-01

    This work is devoted to the evaluation of the efficiency of a new low-temperature plasma jet driven in ambient air by a dc-corona discharge to inactivate adherent cells and biofilms of Gram-positive bacteria. The selected microorganisms were lactic acid bacteria, a Weissella confusa strain which has the particularity to excrete a polysaccharide polymer (dextran) when sucrose is present. Both adherent cells and biofilms were treated with the low-temperature plasma jet for different exposure times. The antimicrobial efficiency of the plasma was tested against adherent cells and 48 h-old biofilms grown with or without sucrose. Bacterial survival was estimated using both colony-forming unit counts and fluorescence-based assays for bacterial cell viability. The experiments show the ability of the low-temperature plasma jet at atmospheric pressure to inactivate the bacteria. An increased resistance of bacteria embedded within biofilms is clearly observed. The resistance is also significantly higher with biofilm in the presence of sucrose, which indicates that dextran could play a protective role.

  9. Simulation of Plasma Jet Merger and Liner Formation within the PLX- α Project

    NASA Astrophysics Data System (ADS)

    Samulyak, Roman; Chen, Hsin-Chiang; Shih, Wen; Hsu, Scott

    2015-11-01

    Detailed numerical studies of the propagation and merger of high Mach number argon plasma jets and the formation of plasma liners have been performed using the newly developed method of Lagrangian particles (LP). The LP method significantly improves accuracy and mathematical rigor of common particle-based numerical methods such as smooth particle hydrodynamics while preserving their main advantages compared to grid-based methods. A brief overview of the LP method will be presented. The Lagrangian particle code implements main relevant physics models such as an equation of state for argon undergoing atomic physics transformation, radiation losses in thin optical limit, and heat conduction. Simulations of the merger of two plasma jets are compared with experimental data from past PLX experiments. Simulations quantify the effect of oblique shock waves, ionization, and radiation processes on the jet merger process. Results of preliminary simulations of future PLX- alpha experiments involving the ~ π / 2 -solid-angle plasma-liner configuration with 9 guns will also be presented. Partially supported by ARPA-E's ALPHA program.

  10. Charge and energy transferred from a plasma jet to liquid and dielectric surfaces

    NASA Astrophysics Data System (ADS)

    Mussard, M. Dang Van Sung; Foucher, E.; Rousseau, A.

    2015-10-01

    A key parameter in using plasma jets for biomedical applications is the transferred energy to the living tissues. The objective of this paper is to understand which parameters control the energy transfer from the plasma jet to a liquid or a dielectric surface. The plasma jet is flown with helium and ignited by a 600 Hz ac high voltage (up to 15 kV). Capacitors are connected to two measurement electrodes placed in the plasma source region, and under the sample. Charge and energy transferred are estimated by plotting Lissajous cycles; the number of bullets and the charge probability density function are also calculated. It is shown that the applied voltage and the gap (distance between the end of the tube and the sample) have a dramatic influence on the energy deposition on the sample as well as on the charge probability density function. Surprisingly, both gap distance and voltage have very little influence on the number of bullets reaching the sample per cycle. It is also shown that the conductivity of the liquid sample has almost no influence on the energy deposition and charge probability density function.

  11. Spatially resolved spectroscopic measurements of a dielectric barrier discharge plasma jet applicable for soft ionization

    NASA Astrophysics Data System (ADS)

    Olenici-Craciunescu, S. B.; Müller, S.; Michels, A.; Horvatic, V.; Vadla, C.; Franzke, J.

    2011-03-01

    An atmospheric pressure microplasma ionization source based on a dielectric barrier discharge with a helium plasma cone outside the electrode region has been developed for liquid chromatography/mass spectrometry and as ionization source for ion mobility spectrometry. It turned out that dielectric barrier discharge ionization could be regarded as a soft ionization technique characterized by only minor fragmentation similar to atmospheric pressure chemical ionization (APCI). Mainly protonated molecules were detected. In order to characterize the soft ionization mechanism spatially resolved optical emission spectrometry (OES) measurements were performed on plasma jets burning either in He or in Ar. Besides to spatial intensity distributions of noble gas spectral lines, in both cases a special attention was paid to lines of N 2+ and N 2. The obtained mapping of the plasma jet shows very different number density distributions of relevant excited species. In the case of helium plasma jet, strong N 2+ lines were observed. In contrast to that, the intensities of N 2 lines in Ar were below the present detection limit. The positions of N 2+ and N 2 distribution maxima in helium indicate the regions where the highest efficiency of the water ionization and the protonation process is expected.

  12. Propagation mechanisms of guided streamers in plasma jets: the influence of electronegativity of the surrounding gas

    NASA Astrophysics Data System (ADS)

    Schmidt-Bleker, Ansgar; Norberg, Seth A.; Winter, Jörn; Johnsen, Eric; Reuter, S.; Weltmann, K. D.; Kushner, Mark J.

    2015-06-01

    Atmospheric pressure plasma jets for biomedical applications are often sustained in He with small amounts of, for example, O2 impurities and typically propagate into ambient air. The resulting poorly controlled generation of reactive species has motivated the use of gas shields to control the interaction of the plasma plume with the ambient gas. The use of different gases in the shield yields different behavior in the plasma plume. In this paper, we discuss results from experimental and computational investigations of He plasma jets having attaching and non-attaching gas shields. We found that negative ion formation in the He-air mixing region significantly affects the ionization wave dynamics and promotes the propagation of negative guided streamers through an electrostatic focusing mechanism. Results from standard and phase resolved optical emission spectroscopy ratios of emission from states of N2 and He imply different electric fields in the plasma plume depending on the composition of the shielding gas. These effects are attributed to the conductivity in the transition region between the plasma plume and the shield gas, and the immobile charge represented by negative ions. The lower conductivity in the attaching mixtures enables more extended penetration of the electric field whereas the negative ions aid in focusing the electrons towards the axis.

  13. Reassessment of the body forces in a He atmospheric-pressure plasma jet: a modelling study

    NASA Astrophysics Data System (ADS)

    Hasan, M. I.; Bradley, J. W.

    2016-02-01

    Using a fully self-consistent fluid model, the impact of the plasma on the background gas flow in an atmospheric-pressure helium plasma jet (He-APPJ) impinging ambient air is investigated through determination of the electrohydrodynamic forces (EHD forces) and gas heating effects. Three gas flow compositions have been considered: a pure helium flow, a helium flow with 2% O2 admixture, and a helium flow with 2% N2 admixture. In all cases, results show that the plasma mainly affects background flow through localized heating, which creates a pressure gradient force acting to increase the flow velocity at the exit of the capillary by approximately 1 to 3 ms-1. The EHD forces on the other hand disturb the flow only slightly. Discharges with O2 and N2 admixtures exhibit increased gas heating and EHD forces. This is attributed to the extra rotational and vibrational excitation states available, coupling electron energy to the background gas. The findings here indicate that a significant increase in the Reynold number as a result of the presence of the plasma is an unlikely explanation for plasma-induced turbulence, observed in atmospheric plasma jet discharges.

  14. Research on OH(A) Production Mechanism of an Atmospheric He-Water Plasma Jet

    NASA Astrophysics Data System (ADS)

    Liu, Jingjing; Hu, Xiao

    2015-09-01

    Hydroxyl radicals produced by atmospheric liquid containing plasmas play important role on bacteria killing and wound healing. A He-H2O plasma jet can produce abundant OH radicals with low gas temperature. At present, some possible reactions to produce OH(A) are concluded, however, the main mechanism to produce OH(A) and the influence of plasma working mode and water vapor concentration on OH(A) generation are still not clear. It is generally regarded that the accurate measurements of electron density and electron temperature play key role on the analysis of OH production mechanism. In this paper, the main generation and loss mechanisms of OH(A) will be found out by both experimental measurements of time-spatial distribution of OH(A) emission intensity, electron density and electron temperature and neutral gas/plasma fluid simulation at different working modes and water vapor concentrations. The influence of plasma working mode and water vapor concentration on OH(A) production and its flux arriving on the substrate is also investigated to optimize the He-H2O plasma jet for bio-medical application.

  15. [Sterilizing effect of atmospheric pressure plasma jet on microbes].

    PubMed

    Wu, Xu-Qin; Wang, Shou-guo; Han, Li; Zhao, Ling-li; Chang, Xiao; Chen, Geng; Suo, Ji-jiang; Xing, Yu-bin; Chen, Shi-ping

    2005-04-01

    To study the sterilizing effect and mechanism of APPJ on microbes preliminarily, three representative bacteria, Staphylococcus aureus, Escherichia coli, Bacillus subtilis var. niger were treated by two kinds of plasma, DBD (dielectric barrier discharge) and APPJ. The survival curves of different microbes were compared and analyzed; Furthermore, the morphological change to cell walls and cell membranes were studied by scanning electric microscope. These results demonstrated that in the beginning phase the sterilizing effect of two kinds of plasmas on three microorganisms was stronger than in the later phase, and APPJ was more effective than DBD (D value of DBD on Bacillus subtilis var. niger was 70 s, whereas APPJ's was 4 s, much more efficient). Meanwhile, the gross morphological damage of E. coli cells under SEM after APPJ treatment was observed. These gave the obvious evidence that APPJ can destroy the microbes very efficiently, and more likely through the damage of cell walls and membranes of microbes treated by APPJ. PMID:15989284

  16. Behavior of alumina particles in atmospheric pressure plasma jets

    SciTech Connect

    Fincke, J.R.; Swank, W.D.

    1990-01-01

    The distribution of Al{sub 2}O{sub 3} particle size, velocity and temperature was mapped over the flow field of a 31.5 kW plasma torch. The effects of varying the powder loading were studied. The powder feed rate was varied between .45 and 2.05 kg/hr independent of the carrier gas flow rate. The particle flow field was non-symmetric due to the method of particle injection. The data indicate that powder feed rate does not significantly affect either the temperature or velocity of the particles, for typical plasma spray conditions, and that the assumption of a dilute particle flow field is valid. 1 ref., 7 figs.

  17. Reduced-order modeling of high-speed jets controlled by arc filament plasma actuators

    NASA Astrophysics Data System (ADS)

    Sinha, Aniruddha; Serrani, Andrea; Samimy, Mo

    2013-02-01

    Arc filament plasma actuators applied to high-speed and high Reynolds number jets have demonstrated significant mixing enhancement when operated near the jet column mode (JCM) frequency. A feedback-oriented reduced-order model is developed for this flow from experimental data. The existent toolkit of stochastic estimation, proper orthogonal decomposition, and Galerkin projection is adapted to yield a 35-dimensional model for the unforced jet. Explicit inclusion of a "shift mode" stabilizes the model. The short-term predictive capability of instantaneous flow fields is found to degrade beyond a single flow time step, but this horizon may be adequate for feedback control. Statistical results from long-term simulations agree well with experimental observations. The model of the unforced jet is augmented to incorporate the effects of plasma actuation. Periodic forcing is modeled as a deterministic pressure wave specified on the inflow boundary of the modeling domain. Simulations of the forced model capture the nonlinear response that leads to optimal mixing enhancement in a small range of frequencies near the JCM.

  18. Experimental investigation of supersonic low pressure air plasma flows obtained with different arc-jet operating conditions

    SciTech Connect

    Lago, Viviana; Ndiaye, Abdoul-Aziz

    2012-11-27

    A stationary arc-jet plasma flow at low pressure is used to simulate some properties of the gas flow surrounding a vehicle during its entry into celestial body's atmospheres. This paper presents an experimental study concerning plasmas simulating a re-entry into our planet. Optical measurements have been carried out for several operating plasma conditions in the free stream, and in the shock layer formed in front of a flat cylindrical plate, placed in the plasma jet. The analysis of the spectral radiation enabled the identification of the emitting species, the determination of the rotational and vibrational temperatures in the free-stream and in the shock layer and the determination of the distance of the shock to the flat plate face. Some plasma fluid parameters like, stagnation pressure, specific enthalpy and heat flux have been determined experimentally along the plasma-jet axis.

  19. Experimental investigation of supersonic low pressure air plasma flows obtained with different arc-jet operating conditions

    NASA Astrophysics Data System (ADS)

    Lago, Viviana; Ndiaye, Abdoul-Aziz

    2012-11-01

    A stationary arc-jet plasma flow at low pressure is used to simulate some properties of the gas flow surrounding a vehicle during its entry into celestial body's atmospheres. This paper presents an experimental study concerning plasmas simulating a re-entry into our planet. Optical measurements have been carried out for several operating plasma conditions in the free stream, and in the shock layer formed in front of a flat cylindrical plate, placed in the plasma jet. The analysis of the spectral radiation enabled the identification of the emitting species, the determination of the rotational and vibrational temperatures in the free-stream and in the shock layer and the determination of the distance of the shock to the flat plate face. Some plasma fluid parameters like, stagnation pressure, specific enthalpy and heat flux have been determined experimentally along the plasma-jet axis.

  20. Comparison of Sterilizing Effect of Nonequilibrium Atmospheric-Pressure He/O2 and Ar/O2 Plasma Jets

    NASA Astrophysics Data System (ADS)

    Li, Shouzhe; Lim, Jinpyo

    2008-02-01

    The sterilizing effect of the non-equilibrium atmospheric pressure plasma jet by applying it to the Bacillus subtilis spores is invesigated. A stable glow discharge in argon or helium gas fed with active gas (oxygen), was generated in the coaxial cylindrical reactor powered by the radio-frequency power supply at atmospheric pressure. The experimental results indicated that the efficiency of killing spores by making use of an Ar/O2 plasma jet was much better than with a He/O2 plasma jet. The decimal reduction value of Ar/O2 and He/O2 plasma jets under the same experimental conditions was 4.5 seconds and 125 seconds, respectively. It was found that there exists an optimum oxygen concentration for a certain input power, at which the sterilization efficiency reaches a maximum value. It is believed that the oxygen radicals are generated most efficiently under this optimum condition.

  1. Spectroscopic Diagnostics and an Arc Jet Heated Air Plasma

    NASA Technical Reports Server (NTRS)

    Mack, Larry Howard, Jr.

    1996-01-01

    Spectral radiation measurements were made in the range of 200 to 900 nm across a section of the plenum of an arc jet wind tunnel using a series of optical fibers. The spectra contained line radiation from Oxygen and Nitrogen atoms and molecular radiation from N2(+), N2, and NO. Abel inversion technique is used to obtain radial distribution of the spectra. The analysis yielded radial profiles of the electronic excitation, vibrational and rotational temperatures of the flow field. Spectral fitting yielded branching ratios for different vibrational and rotational bands. Relatively mild flow conditions, i.e. enthalpy and mass flow rate, were used for prolonged measurements of up to and over two hours to establish the best experimental methods of temperature determinations. Signal to noise was improved by at least an order of magnitude enabling the molecular vibrational band heads of N2(+) (first negative system), N2 (second positive system), and NO (beta, gamma, delta, and epsilon systems) to be resolved in the lower ultraviolet wavelength regions. The increased signal to noise ratio also enabled partial resolution of the rotational lines of N2(+) and N2 in certain regions of minimal overlap. Comparison of the spectra with theoretical models such as the NEQAIR2 code are presented and show potential for fitting the spectra when reliable calibration is performed for the complete wavelength range.

  2. Role of ambient dielectric in propagation of Ar atmospheric pressure nonequilibrium plasma jets

    SciTech Connect

    Song, Jian; Wang, Youyin; Yu, Daren; Tang, Jingfeng Wei, Liqiu; Ren, Chunsheng

    2015-05-15

    A single-electrode atmospheric pressure nonequilibrium plasma jet surrounded with different ambient dielectrics is investigated driven by AC power supply. Another three ambient dielectrics, distilled water, ethanol, and carbon tetrachloride, are adopted to compare with air. By examining electrical and optical characteristics, it was found that the molecular polarity of ambient dielectrics had its significant effect on the propagation of atmospheric pressure nonequilibrium plasma jets. When the polarization of molecules was enhanced, the discharge current and the bullet velocity were also increased. For nonpolar dielectric of carbon tetrachloride, this was mainly resulted from the electron polarization in the built-in electric field. For polar dielectrics of ethanol and distilled water, in addition to the electron polarization, orientation polarization was the main cause for the further increase in discharge current and bullet velocity.

  3. Formation of stable nanostructured phases in plasma-jet-treated Ni-Cr powder coatings

    NASA Astrophysics Data System (ADS)

    Alontseva, D. L.; Bratushka, S. N.; Il'yashenko, M. V.; Makhmudov, N. A.; Prokhorenkova, N. V.; Onanchenko, E. L.; Novgorodtsev, A. I.; Pshik, A. V.; Rogoz, V. N.

    2012-08-01

    Samples of steel St3 with Ni-Cr-B-Si-Fe coatings deposited using a plasma jet with subsequent partial melting of the coatings by a plasma jet have been investigated for the first time using the methods of Rutherford backscattering spectroscopy, scanning electron microscopy, X-ray fluorescence analysis, X-ray photoelectron spectroscopy, and nanoindentation. The structure and the phase and elemental compositions of these coatings have been studied. Ni-based nanocrystalline phases and CrNi3-based microcrystalline phases with crystals from 50 to 150 nm in size, extended defects of the microstructure, and nanoregions with different orientations of the crystal lattice and grain sizes on the order of 2-3 nm have been found.

  4. Particle in cell simulation of a radiofrequency plasma jet expanding in vacuum

    SciTech Connect

    Charles, C. Hawkins, R.; Boswell, R. W.

    2015-03-02

    The effect of a pressure gradient (∼133 Pa–0.133 Pa) on electron and ion energy distributions in a radiofrequency (rf at 13.56 MHz) argon plasma jet is studied using a 1D-3v Particle In Cell (PIC) simulation. The PIC domain is three times that of the 0.018 m long plasma cavity and the total simulation time is 1 ms. Ion heating and acceleration up to a drift velocity about 2000 m s{sup −1} are measured along the jet's main expansion axis. Elastic and charge exchange ion-neutral collisions histograms computed at equilibrium during 0.74 ms show that charge exchange collisions act as the main neutral heating mechanism.

  5. Rayleigh-Taylor-Instability Evolution in Colliding-Plasma-Jet Experiments with Magnetic and Viscous Stabilization

    SciTech Connect

    Adams, Colin Stuart

    2015-01-15

    The Rayleigh-Taylor instability causes mixing in plasmas throughout the universe, from micron-scale plasmas in inertial confinement fusion implosions to parsec-scale supernova remnants. The evolution of this interchange instability in a plasma is influenced by the presence of viscosity and magnetic fields, both of which have the potential to stabilize short-wavelength modes. Very few experimental observations of Rayleigh-Taylor growth in plasmas with stabilizing mechanisms are reported in the literature, and those that are reported are in sub-millimeter scale plasmas that are difficult to diagnose. Experimental observations in well-characterized plasmas are important for validation of computational models used to make design predictions for inertial confinement fusion efforts. This dissertation presents observations of instability growth during the interaction between a high Mach-number, initially un-magnetized plasma jet and a stagnated, magnetized plasma. A multi-frame fast camera captures Rayleigh-Taylor-instability growth while interferometry, spectroscopy, photodiode, and magnetic probe diagnostics are employed to estimate plasma parameters in the vicinity of the collision. As the instability grows, an evolution to longer mode wavelength is observed. Comparisons of experimental data with idealized magnetohydrodynamic simulations including a physical viscosity model suggest that the observed instability evolution is consistent with both magnetic and viscous stabilization. These data provide the opportunity to benchmark computational models used in astrophysics and fusion research.

  6. Qualification of tungsten coatings on plasma-facing components for JET

    NASA Astrophysics Data System (ADS)

    Maier, H.; Neu, R.; Greuner, H.; Böswirth, B.; Balden, M.; Lindig, S.; Matthews, G. F.; Rasinski, M.; Wienhold, P.; Wiltner, A.

    2009-12-01

    This contribution summarizes the work that has been performed to establish the industrial production of tungsten coatings on carbon fibre composite (CFC) for application within the ITER-like Wall Project at JET. This comprises the investigation of vacuum plasma-sprayed coatings, physical vapour deposited tungsten/rhenium multilayers, as well as coatings deposited by combined magnetron-sputtering and ion implantation. A variety of analysis tools were applied to investigate failures and oxide and carbide formation in these systems.

  7. Langmuir probe diagnostics of an atmospheric pressure, vortex-stabilized nitrogen plasma jet

    SciTech Connect

    Prevosto, L.; Mancinelli, B. R.; Kelly, H.

    2012-09-15

    Langmuir probe measurements in an atmospheric pressure direct current (dc) plasma jet are reported. Sweeping probes were used. The experiment was carried out using a dc non-transferred arc torch with a rod-type cathode and an anode of 5 mm diameter. The torch was operated at a nominal power level of 15 kW with a nitrogen flow rate of 25 Nl min{sup -1}. A flat ion saturation region was found in the current-voltage curve of the probe. The ion saturation current to a cylindrical probe in a high-pressure non local thermal equilibrium (LTE) plasma was modeled. Thermal effects and ionization/recombination processes inside the probe perturbed region were taken into account. Averaged radial profiles of the electron and heavy particle temperatures as well as the electron density were obtained. An electron temperature around 11 000 K, a heavy particle temperature around 9500 K and an electron density of about 4 Multiplication-Sign 10{sup 22} m{sup -3}, were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found throughout the plasma jet. The electron and heavy particle temperature profiles showed good agreement with those reported in the literature by using spectroscopic techniques. It was also found that the temperature radial profile based on LTE was very close to that of the electrons. The calculations have shown that this method is particularly useful for studying spraying-type plasma jets characterized by electron temperatures in the range 9000-14 000 K.

  8. METHODS AND MEANS FOR OBTAINING HYDROMAGNETICALLY ACCELERATED PLASMA JET

    DOEpatents

    Marshall, J. Jr.

    1960-11-22

    A hydromagnetic plasma accelerator is described comprising in combination a center electrode, an outer electrode coaxial with the center electrode and defining an annular vacuum chamber therebetween, insulating closure means between the electrodes at one end, means for iniroducing an ionizable gas into the annular vacuum chamber near one end thereof, and means including a power supply for applying a voltage between the electrodes at the end having the closure means, the open ends of the electrodes being adapted for connection to a vacuumed atilization chamber.

  9. Treatment of Candida albicans biofilms with low-temperature plasma induced by dielectric barrier discharge and atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Koban, Ina; Matthes, Rutger; Hübner, Nils-Olaf; Welk, Alexander; Meisel, Peter; Holtfreter, Birte; Sietmann, Rabea; Kindel, Eckhard; Weltmann, Klaus-Dieter; Kramer, Axel; Kocher, Thomas

    2010-07-01

    Because of some disadvantages of chemical disinfection in dental practice (especially denture cleaning), we investigated the effects of physical methods on Candida albicans biofilms. For this purpose, the antifungal efficacy of three different low-temperature plasma devices (an atmospheric pressure plasma jet and two different dielectric barrier discharges (DBDs)) on Candida albicans biofilms grown on titanium discs in vitro was investigated. As positive treatment controls, we used 0.1% chlorhexidine digluconate (CHX) and 0.6% sodium hypochlorite (NaOCl). The corresponding gas streams without plasma ignition served as negative treatment controls. The efficacy of the plasma treatment was determined evaluating the number of colony-forming units (CFU) recovered from titanium discs. The plasma treatment reduced the CFU significantly compared to chemical disinfectants. While 10 min CHX or NaOCl exposure led to a CFU log10 reduction factor of 1.5, the log10 reduction factor of DBD plasma was up to 5. In conclusion, the use of low-temperature plasma is a promising physical alternative to chemical antiseptics for dental practice.

  10. Heat Transfer Between a Plasma Jet and a Metal Surface in a Cut Cavity

    NASA Astrophysics Data System (ADS)

    Veremeichik, A. N.; Sazonov, M. I.; Khvisevich, V. M.; Tsyganov, D. L.

    2015-11-01

    Investigations are presented of the formation of a plasma jet and of the current-density and heat-flux distributions in the process of metal cutting along the cut cavity with direct and reverse polarities of the plasmatron connection. The study of the specific features of heat transfer of the arc with the surface of the cut cavity was carried out on the basis of the developed plasma unit which makes it possible to model the technological process of separating metal cutting. A sectional cut model is proposed which can be used to work out and optimize the methods of determination of cutting parameters.

  11. Integrin activation by a cold atmospheric plasma jet

    NASA Astrophysics Data System (ADS)

    Volotskova, Olga; Stepp, Mary Ann; Keidar, Michael

    2012-05-01

    Current breakthrough research on cold atmospheric plasma (CAP) demonstrates that CAP has great potential in various areas, including medicine and biology, thus providing a new tool for living tissue treatment. In this paper, we explore potential mechanisms by which CAP alters cell migration and influences cell adhesion. We focus on the study of CAP interaction with fibroblasts and corneal epithelial cells. The data show that fibroblasts and corneal epithelial cells have different thresholds (treatment times) required to achieve maximum inhibition of cell migration. Both cell types reduced their migration rates by ˜30-40% after CAP compared to control cells. Also, the impact of CAP treatment on cell migration and persistence of fibroblasts after integrin activation by MnCl2, serum starvation or replating cells onto surfaces coated with integrin ligands is assessed; the results show that activation by MnCl2 or starvation attenuates cells’ responses to plasma. Studies carried out to assess the impact of CAP treatment on the activation state of β1 integrin and focal adhesion size by using immunofluorescence show that fibroblasts have more active β1 integrin on their surface and large focal adhesions after CAP treatment. Based on these data, a thermodynamic model is presented to explain how CAP leads to integrin activation and focal adhesion assembly.

  12. Emission spectroscopy of an atmospheric pressure plasma jet operated with air at low frequency

    NASA Astrophysics Data System (ADS)

    Giuliani, L.; Gallego, J. L.; Minotti, F.; Kelly, H.; Grondona, D.

    2015-03-01

    Low-temperature, high-pressure plasma jets have an extensive use in plasma biology and plasma medicine, such as pathogen deactivation, wound disinfection, stopping of bleeding without damage of healthy tissue, acceleration of wound healing, control of bio-film proliferation, etc. In this work, a spectroscopic characterization of a typical plasma jet, operated in air at atmospheric pressure, is reported. Within the spectrum of wavelengths from 200 to 450 nm all remarkable emissions of N2 were monitored. Spectra of the N2 2nd positive system (C3Πu-B3Πg) emitted in air are the most convenient for plasma diagnostics, since they enable to determine electronic Te, rotational Tr and vibrational Tv temperatures by fitting the experimental spectra with the simulated ones. We used SPECAIR software for spectral simulation and obtained the best fit with all these temperatures about 3500K. The conclusion that all temperatures are equal, and its relatively high value, is consistent with the results of a previous work, where it was found that the experimentally determined electrical characteristic was consistent with the model of a thermal arc discharge, together with a highly collisional cathode sheet.

  13. Direct probing of anode arc root dynamics and voltage instability in a dc non-transferred arc plasma jet

    NASA Astrophysics Data System (ADS)

    Ghorui, S.; Tiwari, N.; Meher, K. C.; Jan, A.; Bhat, A.; Sahasrabudhe, S. N.

    2015-12-01

    The transient dynamics of the anode arc root in a dc non-transferred arc plasma torch is captured through fast photography and directly correlated with the associated voltage instability for the first time. The coexistence of multiple arc roots, the transition to a single arc root, root formation and extinction are investigated for the steady, takeover and re-strike modes of the arc. Contrary to the usual concept, the emerging plasma jet of a dc non-transferred arc plasma torch is found to carry current. An unusually long self-propelled arc plasma jet, a consequence of the phenomenon, is demonstrated.

  14. The effect of plasma jet on morphology of the apoptosis cancer cell

    NASA Astrophysics Data System (ADS)

    Mirpour, Shahriar; Nikkhah, Maryam; Pirouzmand, Somaye; Ghomi, Hamid Reza

    2012-10-01

    In recent years, many studies have been carried out to understand the effect of non-thermal plasma on cancer cells. The previous studies showed that non-thermal plasma has apoptosis effect on cancer cells. Also they discovered that after plasma treatment three distinct regions (Death cells, Void zone and live cells) were observed in wells treated [1]. The aim of this paper is to study the effect of plasma jet on these three regions. For this purpose a variable voltage power supply with 20 kHz frequency are used experimentally. The results showed the detached cells rate were increased by increasing the voltage. [4pt] [1] A. Shashurin, M. Keidar, S. Bronnikov, R. A. Jurjus, and M. A. Stepp, Appl. Phys. Lett. 93, 181501 (2008), DOI:10.1063/1.3020223

  15. A brush-shaped air plasma jet operated in glow discharge mode at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Bao, Wenting; Jia, Pengying; Di, Cong

    2014-07-01

    Using ambient air as working gas, a direct-current plasma jet is developed to generate a brush-shaped plasma plume with fairly large volume. Although a direct-current power supply is used, the discharge shows a pulsed characteristic. Based on the voltage-current curve and fast photography, the brush-shaped plume, like the gliding arc plasma, is in fact a temporal superposition of a moving discharge filament in an arched shape. During it moves away from the nozzle, the discharge evolves from a low-current arc into a normal glow in one discharge cycle. The emission profile is explained qualitatively based on the dynamics of the plasma brush.

  16. Experimental investigation on the characteristics of the plasma jet of a low-current vacuum arc in axial magnetic fields

    NASA Astrophysics Data System (ADS)

    Wang, Cong; Shi, Zongqian; Wu, Bingzhou; Gao, Zhanpeng; Jia, Shenli; Wang, Lijun

    2016-04-01

    In this paper, the characteristics of the plasma jet of a low-current vacuum arc with a single cathode spot (CS) in an external axial magnetic field (AMF) up to 150 mT is investigated experimentally, at a constant arc current ranging from 20 A to 60 A. The experiments are conducted with Cu butt contacts in a demountable vacuum chamber. Images of the plasma jets are photographed with a high-speed digital camera with an exposure time of 2 μs. The uniform constant AMF (B n ) within the inter-contacts region is supplied by Nd-Fe-B permanent magnets. The influence of the external AMF on the shape of the jet near the anode surface as well as in the arc column is mainly investigated. A luminous ‘spot’ is observed on the anode surface facing the position of the CS under a relatively strong AMF. The mechanism of the appearance of the luminous ‘spot’ is proposed to be connected to the secondary plasma originating from the anode. Moreover, with the increase in the strength of the AMF, the spreading angle of the cone-shaped plasma jet in the arc-column region decreases gradually. The plasma jet, subjected to a relatively strong AMF (120 mT and 150 mT), becomes cylindrical in shape in the arc-column region and conical in shape in the near-electrode regions. The overall geometry of the plasma jet looks like a dumbbell.

  17. The influence of the air plasma jet on early adherent events of L929 fibroblasts on cell culture polystyrene plate

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Hwan; Kwon, Jae-Sung; Om, Ji-Yeon; Kim, Yong-Hee; Choi, Eun-Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2012-10-01

    Recently, atmospheric pressure plasma was applied to biological field. The aim of this study was to identify whether the air plasma jet increases fibroblast early attachment under moving motion on the cell culture polystyrene plate. Polystyrene plate was treated with plasma jet using compressed air. After 2 minutes of treatment, L929 was seeded on polystyrene plate as well as on untreated plate. Cells were allowed to attach for 4 hours under 70 RPM. FE-SEM, confocal microscopy and RT-PCR were used to evaluate characters of cells. The results suggested that plasma treatment on the polystyrene plate altered surface energy without change of roughness. In occasion of treatment plate, attached L292 were significantly found but not found on untreated surface. Also, despite the small area of treated center by the flame of the plasma jet, cells were also attached on round surface of the area covered by the flame, which suggests that the effect was not only due to the jet flame but perhaps due to the jet interacting with surrounding atmosphere. In the light of this study, the air plasma jet could be useful for early attachment of L292 on the polystyrene plate under moving motion and can be applied to biomaterials.

  18. Investigations of the surface activation of thermoplastic polymers by atmospheric pressure plasma treatment with a stationary plasma jet

    NASA Astrophysics Data System (ADS)

    Moritzer, Elmar; Nordmeyer, Timo; Leister, Christian; Schmidt, Martin Andreas; Grishin, Artur; Knospe, Alexander

    2016-03-01

    The production of high-quality thermoplastic parts often requires an additional process step after the injection molding stage. This may be a coating, bonding process or a 2K-injection moulding process. A commonly used process to improve the bond strength is atmospheric pressure plasma treatment. A variety of applications are realized with the aid of CNC systems. Although they ensure excellent reproducibility, they make it difficult to implement inline applications. This paper therefore examines the possibility of surface treatment using a stationary plasma jet. However, before it is possible to integrate this technology into a production process, preliminary trials need to be carried out to establish which factors influence the process. Experimental tests were performed using a special test set-up, enabling geometric, plasma-specific parameters to be identified. These results can help with the practical integration of this technology into existing production processes.

  19. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    SciTech Connect

    Jablonowski, H.; Hammer, M. U.; Reuter, S.; Bussiahn, R.; Weltmann, K.-D.; Woedtke, Th. von

    2015-12-15

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100–400 nm) and, in particular, vacuum ultraviolet (VUV, 10–200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH{sub 2}O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H{sub 2}O{sub 2}) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O{sub 2}{sup •−}) and hydroxyl radicals ({sup •}OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  20. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    NASA Astrophysics Data System (ADS)

    Jablonowski, H.; Bussiahn, R.; Hammer, M. U.; Weltmann, K.-D.; von Woedtke, Th.; Reuter, S.

    2015-12-01

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100-400 nm) and, in particular, vacuum ultraviolet (VUV, 10-200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH2O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H2O2) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O2•-) and hydroxyl radicals (•OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  1. Efficiency of excimer molecule formation in plasma jets of inert gas mixtures with SF6 and CCl4

    NASA Astrophysics Data System (ADS)

    Rogulich, V. S.; Starodub, V. P.; Shevera, V. S.

    1988-10-01

    The formation of krypton and xenon monofluorides and monochlorides in continuous plasma jets of inert gas mixtures with SF6 and CCl4 molecules is investigated experimentally. Absolute concentrations of KrF, XeF, KrCl, and XeCl excimer molecules in the jet are determined. The energy efficiency of specific input power conversion to the spontaneous B-X emission in the KrF band is estimated at 2-4 percent. Ways of increasing the concentration of excimer molecules in the plasma jet are analyzed.

  2. Stability and excitation dynamics of an argon micro-scaled atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Dünnbier, M.; Becker, M. M.; Iseni, S.; Bansemer, R.; Loffhagen, D.; Reuter, S.; Weltmann, K.-D.

    2015-12-01

    A megahertz-driven plasma jet at atmospheric pressure—the so-called micro-scaled atmospheric pressure plasma jet (μAPPJ)—operating in pure argon has been investigated experimentally and by numerical modelling. To ignite the discharge in argon within the jet geometry, a self-made plasma tuning unit was designed, which additionally enables measurements of the dissipated power in the plasma itself. Discharges in the α-mode up to their transition to the γ-mode were studied experimentally for varying frequencies. It was found that the voltage at the α-γ transition behaves inversely proportional to the applied frequency f and that the corresponding power scales with an f   3/2law. Both these findings agree well with the results of time-dependent, spatially one-dimensional fluid modelling of the discharge behaviour, where the f  3/2 scaling of the α-γ transition power is additionally verified by the established concept of a critical plasma density for sheath breakdown. Furthermore, phase resolved spectroscopy of the optical emission at 750.39 nm as well as at 810.37 nm and 811.53 nm was applied to analyse the excitation dynamics of the discharge at 27 MHz for different applied powers. The increase of the power leads to an additional maximum in the excitation structure of the 750.39 nm line emission at the α-γ transition point, whereas the emission structure around 811 nm does not change qualitatively. According to the fluid modelling results, this differing behaviour originates from the different population mechanisms of the corresponding energy levels of argon.

  3. Ion Acceleration by Laser Plasma Interaction from Cryogenic Micro Jets - Oral Presentation

    SciTech Connect

    Propp, Adrienne

    2015-08-25

    Processes that occur in extreme conditions, such as in the center of stars and large planets, can be simulated in the laboratory using facilities such as SLAC National Accelerator Laboratory and the Jupiter Laser Facility (JLF) at Lawrence Livermore National Laboratory (LLNL). These facilities allow scientists to investigate the properties of matter by observing their interactions with high power lasers. Ion acceleration from laser plasma interaction is gaining greater attention today due to its widespread potential applications, including proton beam cancer therapy and fast ignition for energy production. Typically, ion acceleration is achieved by focusing a high power laser on thin foil targets through a mechanism called Target Normal Sheath Acceleration. Based on research and recent experiments, we hypothesized that a pure liquid cryogenic jet would be an ideal target for this type of interaction, capable of producing the highest proton energies possible with today’s laser technologies. Furthermore, it would provide a continuous, pure target, unlike metal foils which are consumed in the interaction and easily contaminated. In an effort to test this hypothesis and investigate new, potentially more efficient mechanisms of ion acceleration, we used the 527 nm split beam, frequency-doubled TITAN laser at JLF. Data from the cryogenic jets was limited due to the flow of current up the jet into the nozzle during the interaction, heating the jet and damaging the orifice. However, we acheived a pure proton beam with an indiciation of a monoenergetic feature. Furthermore, data from gold and carbon wires showed surprising and interesting results. Preliminary analysis of data from two ion emission diagnostics, Thomson parabola spectrometers (TPs) and radio chromic films (RCFs), suggests that shockwave acceleration occurred rather than target normal sheath acceleration, the standard mechanism of ion acceleration. Upon completion of the experiment at TITAN, I researched the

  4. Optical properties of the atmospheric pressure helium plasma jet generated by alternative current (a.c.) power supply

    NASA Astrophysics Data System (ADS)

    Ilik, Erkan; Akan, Tamer

    2016-05-01

    In this work, an atmospheric pressure plasma jet (APPJ) was produced to generate cold flowing post-discharge plasma of pure helium gas. The main aim of this study was to generate cold flowing APPJ of pure helium gas and to determine how their optical emission spectrum change influences varying different flow rates. Lengths of early, middle, and late post-discharge plasma (jet) regions and their fluctuations were determined, respectively. Then, ignition condition dependence of the post-discharge plasma for flow rate was specified at a constant voltage. Spectroscopic studies of an atmospheric pressure plasma jet of helium were presented via analyzing OH, N2, N2+, oxygen, and helium intensities for various flow rates.

  5. Interphase Momentum and Heat Exchange in Turbulent Dust-Laden Plasma Jet under Continuous Radial Powder Injection

    SciTech Connect

    Solonenko, Oleg P.; Smirnov, Audrey V.

    2006-05-05

    Potential possibilities of an advanced approach based on the usage of DC cascade torch providing an axially symmetric plasma jet outflow, and continuous radial injection of powder into a plasma flow are discussed. Comparison is made of the results, obtained using two models of interphase heat and momentum exchange between polydisperse alumina particles and air plasma jet, other factors being the same. The widely used model of gradientless particles' heating was applied for computing the two-phase plasma jets' temperature and velocity fields. The model is compared with corresponding model of gradient particle heating computed by using an efficient numerical method developed. Calculations were conducted under different scales of dense loading conditions to estimate the maximum productivity of plasma spray process.

  6. OH radicals distribution in an Ar-H2O atmospheric plasma jet

    NASA Astrophysics Data System (ADS)

    Li, L.; Nikiforov, A.; Xiong, Q.; Britun, N.; Snyders, R.; Lu, X.; Leys, C.

    2013-09-01

    Recently, plasma jet systems found numerous applications in the field of biomedicine and treatment of temperature-sensitive materials. OH radicals are one of the main active species produced by these plasmas. Present study deals with the investigation of RF atmospheric pressure plasma jet in terms of OH radicals production by admixture of H2O into argon used as a feed gas. Generation of OH radicals is studied by laser-induced fluorescence spectroscopy. The excitation dynamics of OH radicals induced by the laser photons is studied by time-resolved spectroscopy. It is shown that vibrational and rotational energy transfer processes, which are sensitive to the surrounding species, can lead to the complication in the OH radicals diagnostics at high pressure and have to be considered during experiments. The axial and radial 2D maps of absolute densities of hydroxyl radicals at different water contents are obtained. The highest density of 1.15 × 1020 m-3 is measured in the plasma core for the case of 0.3% H2O. In the x-y-plane, the OH density steeply decreases within a range of ±2 mm from its maximum value down to 1018 m-3. The effect of H2O addition on the generation of OH radicals is investigated and discussed.

  7. OH radicals distribution in an Ar-H{sub 2}O atmospheric plasma jet

    SciTech Connect

    Li, L.; Leys, C.; Nikiforov, A.; Xiong, Q.; Britun, N.; Snyders, R.; Lu, X.

    2013-09-15

    Recently, plasma jet systems found numerous applications in the field of biomedicine and treatment of temperature-sensitive materials. OH radicals are one of the main active species produced by these plasmas. Present study deals with the investigation of RF atmospheric pressure plasma jet in terms of OH radicals production by admixture of H{sub 2}O into argon used as a feed gas. Generation of OH radicals is studied by laser-induced fluorescence spectroscopy. The excitation dynamics of OH radicals induced by the laser photons is studied by time-resolved spectroscopy. It is shown that vibrational and rotational energy transfer processes, which are sensitive to the surrounding species, can lead to the complication in the OH radicals diagnostics at high pressure and have to be considered during experiments. The axial and radial 2D maps of absolute densities of hydroxyl radicals at different water contents are obtained. The highest density of 1.15 × 10{sup 20} m{sup −3} is measured in the plasma core for the case of 0.3% H{sub 2}O. In the x–y-plane, the OH density steeply decreases within a range of ±2 mm from its maximum value down to 10{sup 18} m{sup −3}. The effect of H{sub 2}O addition on the generation of OH radicals is investigated and discussed.

  8. Stabilization of sawteeth with third harmonic deuterium ICRF-accelerated beam in JET plasmas

    NASA Astrophysics Data System (ADS)

    Girardo, Jean-Baptiste; Sharapov, Sergei; Boom, Jurrian; Dumont, Rémi; Eriksson, Jacob; Fitzgerald, Michael; Garbet, Xavier; Hawkes, Nick; Kiptily, Vasily; Lupelli, Ivan; Mantsinen, Mervi; Sarazin, Yanick; Schneider, Mireille

    2016-01-01

    Sawtooth stabilisation by fast ions is investigated in deuterium (D) and D-helium 3 (He3) plasmas of JET heated by deuterium Neutral Beam Injection combined in synergy with Ion Cyclotron Resonance Heating (ICRH) applied on-axis at 3rd beam cyclotron harmonic. A very significant increase in the sawtooth period is observed, caused by the ICRH-acceleration of the beam ions born at 100 keV to the MeV energy range. Four representative sawteeth from four different discharges are compared with Porcelli's model. In two discharges, the sawtooth crash appears to be triggered by core-localized Toroidal Alfvén Eigenmodes inside the q = 1 surface (also called "tornado" modes) which expel the fast ions from within the q = 1 surface, over time scales comparable with the sawtooth period. Two other discharges did not exhibit fast ion-driven instabilities in the plasma core, and no degradation of fast ion confinement was found in both modelling and direct measurements of fast ion profile with the neutron camera. The developed sawtooth scenario without fast ion-driven instabilities in the plasma core is of high interest for the burning plasmas. Possible causes of the sawtooth crashes on JET are discussed.

  9. Jet-conversion photons from an anisotropic quark-gluon plasma

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Lusaka; Roy, Pradip

    2010-10-01

    We calculate the pT distributions of jet-conversion photons from a quark-gluon plasma with pre-equilibrium momentum-space anisotropy. A phenomenological model has been used for the time evolution of the hard momentum scale phard(τ) and anisotropy parameter ξ(τ). As a result of pre-equilibrium momentum-space anisotropy, we find significant modification of the jet-conversion photon pT distribution. For example, with fixed initial condition pre-equilibrium anisotropy, we predict a significant enhancement of the jet-photon pT distribution in the entire region, whereas for pre-equilibrium anisotropy with fixed final multiplicity (FFM), suppression of the jet-conversion photon pT distribution is observed. The results with FFM (as it is the most realistic situation) have been compared with high pT PHENIX photon data. It is found that the data are reproduced well if the isotropization time lies within 1.5 fm/c.

  10. Plasma synthetic jet actuator: electrical and optical analysis of the discharge

    NASA Astrophysics Data System (ADS)

    Belinger, A.; Naudé, N.; Cambronne, J. P.; Caruana, D.

    2014-08-01

    Active flow control is based on the development of robust actuators which are reliable, small and easy to integrate. A promising actuator referred to as plasma synthetic jet actuator produces a synthetic jet with high exhaust velocities and holds the promise of enabling high-speed flows. With this high velocity jet, it is possible to reduce fluid phenomena such as transition and turbulence, thus making it possible to increase an aircraft's performance whilst at the same time reducing its environmental impact. This high velocity jet is produced by a pulsed discharge in a microcavity. In this paper, we focus on the properties of the discharge in order to understand the functioning of the actuator. In the first part an electrical description of the discharge in presented. Afterwards, optical measurements (optical emission spectroscopy and ICCD photograph) enable the determination of temperature, volume and duration of the discharge. At the end of the paper we present an electrical model of the discharge, which can be obtained both from electrical measurements and from macroscopic properties of the discharge (temperature, volume). This electrical model can easily be included in electrical simulation software.

  11. Effect of atmospheric pressure plasma jet on the foodborne pathogens attached to commercial food containers.

    PubMed

    Kim, Hyun-Joo; Jayasena, Dinesh D; Yong, Hae In; Alahakoon, Amali U; Park, Sanghoo; Park, Jooyoung; Choe, Wonho; Jo, Cheorun

    2015-12-01

    Bacterial biofilms are associated with numerous infections and problems in the health care and food industries. The aim of this study was to evaluate the bactericidal effect of an atmospheric pressure plasma (APP) jet on Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium biofilm formation on collagen casing (CC), polypropylene (PP) and polyethylene terephthalate (PET), which are widely used food container materials. The samples were treated separately with the APP jet at a 50-W input power for 5 and 10 min, and nitrogen (6 l per minute) gas combined with oxygen (10 standard cubic centimeters per minute) was used to produce the APP. The APP jet reduced the number of bacterial cells in a time-dependent manner. All pathogens attached to CC, PP, and PET were reduced by 3-4 log CFU/cm(2) by the 10-min APP treatment. The developed APP jet was effectively reduced biofilms on CC, PP, and PET. PMID:26604423

  12. Separation control using plasma actuators: application to a free turbulent jet

    NASA Astrophysics Data System (ADS)

    Labergue, A.; Moreau, E.; Zouzou, N.; Touchard, G.

    2007-02-01

    This experimental work deals with active airflow control using non-thermal surface plasma actuators in the case of a rectangular cross section turbulent jet. A wide-angle diffuser composed of two adjustable hinged baseplates is linked at the jet exit. Two types of actuators are considered: the DC corona discharge and the dielectric barrier discharge (DBD). In both cases, an ionic wind with a velocity of several m s-1 is generated tangentially to the wall surface. Thus, this induced aerodynamic effect is applied in order to create the separation along the lower hinged baseplate. The effects of both actuators on the flow separation are measured by means of particle image velocimetry for velocity up to 30 m s-1. The main results show that the DBD seems more efficient than the DC corona discharge but the effect decreases with the jet velocity. However, in increasing the discharge frequency up to 1500 Hz, it is possible to separate a 30 m s-1 jet. Finally, by reducing the actuators' length in the spanwise direction, results lead to a visualization of the three-dimensional effects on the separation along the lower hinged baseplate.

  13. [The Characteristic Research of ·OH Induced by Water on an Argon Plasma Jet].

    PubMed

    Liu, Kun; Liao, Hua; Zheng, Pei-chao; Wang, Chen-ying; Liu, Hong-di; Danil, Dobrynin

    2015-07-01

    ·OH plays a crucial role in many fields, having aroused wide public concern in the world. Atmospheric Pressure Plasma Jet, which can be achieved by portable device due to working without the vacuum environment, has the advantages of high concentration of reactive species, high electron temperature and low gas temperature. It has become an important research topic in the field of gas discharge with a strong prospect. Especially, how to induce plasma jet to produce ·OH has become a new hotpot in the field of low-temperature plasma. It has been reported that mass ·OH can be induced successfully when water vapor is added to the working gas, but it will be unstable when the concentrate of water reaches a certain degree. Thus, a device of argon plasma jet with a Ring-to-Ring Electrode Configuration has been designed to interact with water in the surrounding air to generate ·OH under atmospheric pressure. In order to increase the production of ·OH, ultrasonic atomizing device is introduced to promote water concentration around the plasma plume. The generating rule of OH(A2J) induced by water has been extensively studied under different voltages and flow rate. ·OH output induced by the plasma has been tested by emission spectrometry, and at the meanwhile, Ar atomic spectral lines at 810.41 and 811.48 nm are also recorded in order to calculate the electron temperature in argon plasma plume. The results show that the water surrounding the plasma plume can be induced to produce ·OH, and OH(A2 ∑+) output increases with the electrode voltage rising from 20 to 28 kV. When the flow rate increases from 100 to 200 L x h(-1), the OH(A2∑+) output increases, but from 200 to 600 L x h(-1), it decreases. The production rules of OH(A2∑+) is the same as that of electron temperature. Therefore, the presumption is proved that ·OH output mainly affected by electron temperature. PMID:26717727

  14. Metastable helium atom density in a single electrode atmospheric plasma jet during sample treatment

    NASA Astrophysics Data System (ADS)

    Zaplotnik, R.; Bišćan, M.; Popović, D.; Mozetič, M.; Milošević, S.

    2016-06-01

    The metastable He atoms play an important role in atmospheric pressure plasma jet (APPJ) chemistry processes and in the plasma generation. This work presents cavity ring-down spectroscopy (CRDS) investigation of metastable helium atom (2{{3}}{{S}1} ) densities in a single electrode APPJ during sample treatment. A spatially resolved density distribution of a free jet (without sample) was measured at a He flow rate of 2 slm. The maximum measured density of a free jet was around 7× {{10}11} cm‑3. With the insertion of a sample the densities increased up to 10 times. Helium metastable atoms, in a single electrode helium APPJ (2 slm, ≈2.5 kV, pulsed DC, 10 kHz repetition rate), decayed exponentially with a mean lifetime of 0.27+/- 0.03 μs. Eight different samples of the same sizes but different conductivities were used to investigate the influence of a sample material on the He metastable densities. The correlation between sample conductivities and metastable He densities above the sample surface was found. Metastable He density can also be further increased with decreasing sample distance, increasing conductive sample surface area and by increasing He flow.

  15. Probing the quark-gluon plasma at the LHC with Z0-tagged jets in CMS

    SciTech Connect

    Mironov, C; Castro, M; Constantin, P; Kunde, G J; Vogt, R

    2007-03-12

    An important tool in quark-gluon plasma studies at RHIC has been the measurement of dijets investigated via leading hadron correlations. With much higher rates for hard processes at the Large Hadron Collider, studies of Z{sup 0}-tagged jets become possible. A clear experimental signature is provided by the measurement of muon pairs from the Z{sup 0} decays, for which CMS is an ideally suited detector. Instead of measuring back-to-back correlations of two strongly interacting particles, one side is replaced by an electromagnetic probe which propagates through the plasma undisturbed and provides a measurement of the energy of the initial hard scattering. We propose to use lepton-pair tagged jets to study medium-induced partonic energy loss and to measure in-medium parton fragmentation functions. The lepton pairs from semileptonic decays of heavy meson pairs (B{bar B} and D{bar D}) are a background source for the tagged dilepton-jet signal. We present the calculated signal rates (using PYTHIA) and background rates (using HVQMNR). We also discuss strategies for maximizing the signal-to-background ratio.

  16. Fluid model of a single striated filament in an RF plasma jet at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Sigeneger, F.; Loffhagen, D.

    2016-06-01

    The filaments occurring in an RF argon atmospheric-pressure plasma jet are investigated by means of numerical modelling. The special setup of the jet leads to the establishment of filaments in very regular modes under certain conditions. Such a single filament generated in the active volume between the powered and grounded electrode is described by a time-dependent, spatially two-dimensional fluid model. This self-consistent model includes those mechanisms which can lead to constriction and stratification such as the heat balance equation and the dependence of electron collision rate coefficients on the ionization degree. A curved filament with a contracted radial profile of particle densities and very pronounced striations along its trace has been obtained by the model calculation for a typical discharge parameter condition of the plasma jet. The resulting calculated electron density and mean energy in the filament as well as the period length of the striations agree qualitatively with recent experimental observations. The analysis of the ionization budget makes clear that the constriction and stratification is mainly caused by the different nonlinear dependences of ionization and recombination rates on the electron density.

  17. A new plasma-driven pulsed jet actuator for flow control

    NASA Astrophysics Data System (ADS)

    Bonnet, Jean-Paul; Acher, Gwenael; Lebedev, Anton; Benard, Nicolas; Moreau, Eric; Electro-Fluido Group Team

    2015-11-01

    Active flow control requires actuators with enough authority and high frequency response. Synthetic jets can have high frequency response but are rather limited in terms of authority providing the exit velocity is limited. Pressurized (flowing) jets have a very high potential in terms of authority particularly for high velocity flow control purposes. However, for most purposes, high frequency modulation (of order of several kHz) is required in order to excite most unstable modes and to operate in closed mode. Rapid mechanical valves are limited in terms of frequency (up to typically a few hundred of Hz). We develop a new generation of plasma-driven pulsation of flowing jet. The principle is to increase the temperature at the sonic throat through a plasma discharge located at the throat. The flow rate being proportional to the square root of the temperature for a perfect gas, for the same settling chamber pressure, the actuator flow rate can be varied. The frequency is then no limited by any mechanical constraint. A demonstrator has been tested with a 1mm sonic throat. The electric discharge is created by a 10 kV voltage applied between the anode and the throat acting as the cathode. Within these conditions, a 30% modulation of the flow rate can be obtained.

  18. Study of jet fluctuations in DC plasma torch using high speed camera

    NASA Astrophysics Data System (ADS)

    Tiwari, Nirupama; Sahasrabudhe, S. N.; Joshi, N. K.; Das, A. K.

    2010-02-01

    The power supplies used for the plasma torches are usually SCR controlled and have a large ripple factor. This is due to the fact that the currents in the torch are of the order of hundreds of amperes which prohibit effective filtering of the ripple. The voltage and current vary as per the ripple in the power supply and causes plasma jet to fluctuate. To record these fluctuations, the jet coming out from a D.C. plasma torch operating at atmospheric pressure was imaged using high speed camera at the rate of 3000 frame per second. Light emitted from a well defined zone in the plume was collected using an optical fibre and a Photo Multiplier Tube. Current, voltage and PMT signals were recorded simultaneously using a digital storage oscilloscope (DSO). The fast camera recorded the images for 25 ms and the starting pulse from the camera was used to trigger the DSO for recording voltage, current and optical signals. Each image of the plume recorded by the fast camera was correlated with the magnitude of the instantaneous voltage, current and optical signal. It was observed that the luminosity and length of the plume varies as per the product of instantaneous voltage and current i.e. electrical power fed to plasma torch. The experimental runs were taken with different gas flow rates and electrical powers. The images were analyzed using image processing software and constant intensity contours of images were determined. Further analysis of the images can provide a great deal of information about dynamics of the jet.

  19. Temperature diagnostics of a non-thermal plasma jet at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Schäfer, Jan

    2013-09-01

    The study reflects the concept of the temperature as a physical quantity resulting from the second thermodynamic law. The reliability of different approaches of the temperature diagnostics of open non-equilibrium systems is discussed using examples of low temperature atmospheric pressure discharges. The focus of this work is a miniaturized non-thermal atmospheric pressure plasma jet for local surface treatment at ambient atmosphere. The micro-discharge is driven with a capacitively coupled radio frequency electric field at 27.12 MHz and fed with argon at rates of about 1 slm through the capillary with an inner diameter of 4 mm. The discharge consists of several contracted filaments with diameter around 300 μm which are rotating azimuthally in the capillary in a self-organized manner. While the measured temperatures of the filament core exceed 700 K, the heat impact on a target below the plasma jet remains limited leading to target temperatures below 400 K. Different kinds of temperatures and energy transport processes are proposed and experimentally investigated. Nevertheless, a reliable and detailed temperature diagnostics is a challenge. We report on a novel diagnostics approach for the spatially and temporally resolved measurement of the gas temperature based on the optical properties of the plasma. Laser Schlieren Deflectometry is adapted to explore temperature profiles of filaments and their behaviour. In parallel, the method demonstrates a fundamental Fermat's principle of minimal energy. Information acquired with this method plays an important role for the optimization of local thin film deposition and surface functionalization by means of the atmospheric pressure plasma jet. The work was supported in part by the Deutsche Forschungsgemeinschaft within SFB-TR 24.

  20. Investigation of a Gas Jet-Produced Hollow Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, N; Blumenfeld, I.; Hogan, M.J.; Siemann, R.H.; Walz, D.R.; Davidson, A.W.; Huang, C.; /UCLA

    2009-05-21

    The effect of ion motion and the need for practical positron propagation in a plasma wakefield accelerator (PWFA) have incited interest in hollow plasma channels. These channels are typically assumed to be cylindrically symmetric; however, a different geometry might be easier to achieve. The introduction of an obstruction into the outlet of a high Mach number gas jet can produce two parallel slabs of gas separated by a density depression. Here, there is a detailed simulation study of the density depression created in such a system. This investigation reveals that the density depression is insufficient at the desired plasma density. However, insights from the simulations suggest another avenue for the creation of the hollow slab geometry.

  1. Self-consistent fluid modeling and simulation on a pulsed microwave atmospheric-pressure argon plasma jet

    SciTech Connect

    Chen, Zhaoquan; Yin, Zhixiang Chen, Minggong; Hong, Lingli; Hu, Yelin; Huang, Yourui; Xia, Guangqing; Liu, Minghai; Kudryavtsev, A. A.

    2014-10-21

    In present study, a pulsed lower-power microwave-driven atmospheric-pressure argon plasma jet has been introduced with the type of coaxial transmission line resonator. The plasma jet plume is with room air temperature, even can be directly touched by human body without any hot harm. In order to study ionization process of the proposed plasma jet, a self-consistent hybrid fluid model is constructed in which Maxwell's equations are solved numerically by finite-difference time-domain method and a fluid model is used to study the characteristics of argon plasma evolution. With a Guass type input power function, the spatio-temporal distributions of the electron density, the electron temperature, the electric field, and the absorbed power density have been simulated, respectively. The simulation results suggest that the peak values of the electron temperature and the electric field are synchronous with the input pulsed microwave power but the maximum quantities of the electron density and the absorbed power density are lagged to the microwave power excitation. In addition, the pulsed plasma jet excited by the local enhanced electric field of surface plasmon polaritons should be the discharge mechanism of the proposed plasma jet.

  2. Effects of the nozzle design on the properties of plasma jet and formation of YSZ coatings under low pressure conditions

    NASA Astrophysics Data System (ADS)

    Sun, Chengqi; Gao, Yang; Yang, Deming; Fu, Yingqing

    2016-06-01

    How to control the quality of the coatings has become a major problem during the plasma spraying. Because nozzle contour has a great influence on the characteristic of the plasma jet, two kinds of plasma torches equipped with a standard cylindrical nozzle and a converging-diverging nozzle are designed for low pressure plasma spraying(LPPS) and very low pressure plasma spraying(VLPPS). Yttria stabilized zirconia(YSZ) coatings are obtained in the reducing pressure environment. The properties of the plasma jet without or with powder injection are analyzed by optical emission spectroscopy, and the electron temperature is calculated based on the ratio of the relative intensity of two Ar I spectral lines. The results show that some of the YSZ powder can be vaporized in the low pressure enlarged plasma jet, and the long anode nozzle may improve the characteristics of the plasma jet. The coatings deposited by LPPS are mainly composed of the equiaxed grains and while the unmelted powder particles and large scalar pores appear in the coatings made by VLPPS. The long anode nozzle could improve the melting of the powders and deposition efficiency, and enhance the coatings' hardness. At the same time, the long anode nozzle could lead to a decrease in the overspray phenomenon. Through the comparison of the two different size's nozzle, the long anode is much more suitable for making the YSZ coatings.

  3. Power source effects of soft plasma jet and the differential response of skin cancer and normal cells

    NASA Astrophysics Data System (ADS)

    Taylor, Nathaniel; Dobrynin, Danil; Fridman, Alexander; Choi, Eun Ha

    2014-10-01

    The effects of pulsed power direct current energy sources were compared using an indirect discharge plasma jet applied to treat cancerous and normal skin cells. Two power supplies with different voltage and current profiles were compared and optimized through the measurement of physical parameters and evaluated through the treatment of skin cells using an atmospheric pressure nitrogen gas plasma jet. Plasma density and temperature, power output, gas output temperature, and reactive species production were measured. Cell morphology, viability, and ROS generation were investigated using staining. A differential response has been shown between the normal and cancerous cell lines. The cancer cells viability reduced while normal cells did not over the same treatment time.

  4. 3D printing of gas jet nozzles for laser-plasma accelerators

    NASA Astrophysics Data System (ADS)

    Döpp, A.; Guillaume, E.; Thaury, C.; Gautier, J.; Ta Phuoc, K.; Malka, V.

    2016-07-01

    Recent results on laser wakefield acceleration in tailored plasma channels have underlined the importance of controlling the density profile of the gas target. In particular, it was reported that the appropriate density tailoring can result in improved injection, acceleration, and collimation of laser-accelerated electron beams. To achieve such profiles, innovative target designs are required. For this purpose, we have reviewed the usage of additive layer manufacturing, commonly known as 3D printing, in order to produce gas jet nozzles. Notably we have compared the performance of two industry standard techniques, namely, selective laser sintering (SLS) and stereolithography (SLA). Furthermore we have used the common fused deposition modeling to reproduce basic gas jet designs and used SLA and SLS for more sophisticated nozzle designs. The nozzles are characterized interferometrically and used for electron acceleration experiments with the Salle Jaune terawatt laser at Laboratoire d'Optique Appliquée.

  5. 3D printing of gas jet nozzles for laser-plasma accelerators.

    PubMed

    Döpp, A; Guillaume, E; Thaury, C; Gautier, J; Ta Phuoc, K; Malka, V

    2016-07-01

    Recent results on laser wakefield acceleration in tailored plasma channels have underlined the importance of controlling the density profile of the gas target. In particular, it was reported that the appropriate density tailoring can result in improved injection, acceleration, and collimation of laser-accelerated electron beams. To achieve such profiles, innovative target designs are required. For this purpose, we have reviewed the usage of additive layer manufacturing, commonly known as 3D printing, in order to produce gas jet nozzles. Notably we have compared the performance of two industry standard techniques, namely, selective laser sintering (SLS) and stereolithography (SLA). Furthermore we have used the common fused deposition modeling to reproduce basic gas jet designs and used SLA and SLS for more sophisticated nozzle designs. The nozzles are characterized interferometrically and used for electron acceleration experiments with the Salle Jaune terawatt laser at Laboratoire d'Optique Appliquée. PMID:27475557

  6. A study of the glow discharge plasma jet of the novel Hamburger-electrode

    NASA Astrophysics Data System (ADS)

    Liu, Wenzheng; Ma, Chuanlong; Yang, Xiao; Cui, Weisheng; Chen, Xiuyang

    2016-08-01

    To generate atmospheric pressure glow discharge plasma jets (APGDPJs), a novel Hamburger-electrode was proposed. Through the study on electric field distributions, flow field distributions, and characteristics of the discharge and jet, we found that adopting the mode of dielectric barrier discharge with non-uniform thickness of dielectric, it was easy to form the strong electric field areas which were conducive to generate discharge and electric field distributions with large electric field intensity in the narrow gap and weak electric field intensity in the wide gap that were not inclined to form a filament discharge. Using the structure of evenly distributed inner electrodes, it was easy to weaken the pressure of strong electric field areas and form flow field distributions which is beneficial for taking out the high density charged particles and generating APGDPJs. Stable APGDPJs in nitrogen with 3.5 mm in diameter and 9 mm in length were formed by using the novel Hamburger-electrode.

  7. Cosmic jets

    NASA Technical Reports Server (NTRS)

    Rees, M. J.

    1986-01-01

    The evidence that active galactic nuclei produce collimated plasma jets is summarised. The strongest radio galaxies are probably energised by relativistic plasma jets generated by spinning black holes interacting with magnetic fields attached to infalling matter. Such objects can produce e(+)-e(-) plasma, and may be relevant to the acceleration of the highest-energy cosmic ray primaries. Small-scale counterparts of the jet phenomenon within our own galaxy are briefly reviewed.

  8. OH density optimization in atmospheric-pressure plasma jet by using multiple ring electrodes

    NASA Astrophysics Data System (ADS)

    Yue, Y.; Pei, X.; Lu, X.

    2016-01-01

    OH radical is one of the important reactive species generated by non-equilibrium atmospheric-pressure plasma jets, which is believed to play an important role in plasma medicine applications such as cancer therapy, wound healing and sterilization. In this study, a method to increase OH density is proposed. By using multiple pairs of ring electrodes, we generate 3-5 times more OH radicals than in the common device which uses only one high-voltage ring electrode. Discharge imaging shows that the plasma plume with only one ring electrode is longer and its emission intensity is higher than those with multiple pairs of ring electrodes. Further studies indicate that the distribution of OH radicals is significantly influenced by the gas flow rate. At higher gas flow rates, the OH peak concentration is detected further away from the nozzle, and the position of the peak OH concentration correlates with the product of the gas flow velocity and the pulse duration. As observed from the emission spectra, multiple electrodes only enhance the plasma inside the tube rather than the plasma plume in the surrounding air. These results suggest that the OH radicals are mainly generated inside the tube and then delivered to the outer plasma plume region by the gas flow.

  9. Functionalization of graphene by atmospheric pressure plasma jet in air or H2O2 environments

    NASA Astrophysics Data System (ADS)

    Huang, Weixin; Ptasinska, Sylwia

    2016-03-01

    The functionalization of graphene, which deforms its band structure, can result in a metal-semiconductor transition. In this work, we report a facile strategy to oxidize single-layer graphene using an atmospheric pressure plasma jet (APPJ) that generates a variety of reactive plasma species at close to ambient temperature. We systematically characterized the oxygen content and chemical structure of the graphene films after plasma treatment under different oxidative conditions (ambient air atmosphere or hydrogen peroxide solution) by X-ray Photoelectron Spectroscopy (XPS). Plasma-treated graphene films containing more than 40% oxygen were obtained in both oxidative environments. Interestingly, prolonged irradiation led to the reduction of graphene oxides. N-doping of graphene also occurred during the APPJ treatment in H2O2 solution; the nitrogen content of the doped graphene was dependent on the duration of irradiation and reached up to 8.1% within 40 min. Moreover, the H2O2 solution served as a buffer layer that prevented damage to the graphene during plasma irradiation. Four-point probe measurement revealed an increase in sheet resistance of the plasma-treated graphene, indicating the transition of the material property from semi-metallic to semiconducting.

  10. In Vitro Antimicrobial Effect of a Cold Plasma Jet against Enterococcus faecalis Biofilms

    PubMed Central

    Jiang, Chunqi; Schaudinn, Christoph; Jaramillo, David E.; Webster, Paul; Costerton, J. William

    2012-01-01

    The hypothesis that a cold plasma jet has the antimicrobial effect against Enterococcus faecalis biofilms was tested in vitro. 27 hydroxyapatite discs were incubated with E. faecalis for six days to form a monoculture biofilm on the disc surface. The prepared substrata were divided into three groups: the negative control, the positive control (5.25% NaOCl solution), and the plasma treatment group. Resultant colony-forming unit counts were associated with observations of bacterial cell morphology changes using scanning electron microscopy (SEM). Treatment of E. faecalis biofilm with the plasma and 5.25% NaOCl for 5 min resulted in 93.1% and 90.0% kill (P < 0.0001), respectively. SEM detected that nearly no intact bacteria were discernible for the plasma-exposed HA disc surfaces. The demonstrated bactericidal effect of the plasma with direct surface contact may be due to the enhanced oxidation by the locally produced reactive plasma species. PMID:22461988

  11. N=2 ICRH of H majority plasmas in JET-ILW

    SciTech Connect

    Lerche, E.; Van Eester, D.; Kazakov, Y.; Crombé, K.; Jacquet, P.; Monakhov, I.; Rimini, F.; Kiptily, V.; Santala, M.; Goniche, M.; Colas, L.; Dumont, R.; Collaboration: EUROfusion Consortium

    2015-12-10

    Heating single ion species plasmas with ICRF is a challenging task: Fundamental ion cyclotron heating (w = w{sub ci}) suffers from the adverse polarization of the RF electric fields near the majority cyclotron resonance while second harmonic heating (w = 2w{sub ci}) typically requires pre-heating of the plasma ions to become efficient. Recently, w = 2w{sub ci} ICRF heating was tested in JET-ILW hydrogen plasmas in the absence of neutral beam injection (L-mode). Despite the lack of pre-heating, up to 6MW of ICRF power were coupled to the plasma leading to a transition to H-mode for P{sub ICRH}>5MW in most discharges. Heating efficiencies between 0.65-0.85 were achieved as a combination of the low magnetic field adopted (enhanced finite Larmor radius effects) and the deliberate slow rise of the ICRF power, allowing time for a fast ion population to gradually build-up leading to a systematic increase of the wave absorptivity. Although fast ion tails are a common feature of harmonic ICRF heating, the N=2 majority heating features moderate tail energies (<500keV) except at very low plasma densities (n{sub e0}<3x10{sup 19}/m{sup 3}), where fast H tails in the MeV range developed and fast ion losses became significant, leading to enhanced plasma wall interaction. The main results of these experiments will be reported.

  12. N=2 ICRH of H majority plasmas in JET-ILW

    NASA Astrophysics Data System (ADS)

    Lerche, E.; Van Eester, D.; Kazakov, Y.; Jacquet, P.; Monakhov, I.; Goniche, M.; Colas, L.; Rimini, F.; Crombé, K.; Dumont, R.; Kiptily, V.; Santala, M.

    2015-12-01

    Heating single ion species plasmas with ICRF is a challenging task: Fundamental ion cyclotron heating (w = wci) suffers from the adverse polarization of the RF electric fields near the majority cyclotron resonance while second harmonic heating (w = 2wci) typically requires pre-heating of the plasma ions to become efficient. Recently, w = 2wci ICRF heating was tested in JET-ILW hydrogen plasmas in the absence of neutral beam injection (L-mode). Despite the lack of pre-heating, up to 6MW of ICRF power were coupled to the plasma leading to a transition to H-mode for PICRH>5MW in most discharges. Heating efficiencies between 0.65-0.85 were achieved as a combination of the low magnetic field adopted (enhanced finite Larmor radius effects) and the deliberate slow rise of the ICRF power, allowing time for a fast ion population to gradually build-up leading to a systematic increase of the wave absorptivity. Although fast ion tails are a common feature of harmonic ICRF heating, the N=2 majority heating features moderate tail energies (<500keV) except at very low plasma densities (ne0<3x1019/m3), where fast H tails in the MeV range developed and fast ion losses became significant, leading to enhanced plasma wall interaction. The main results of these experiments will be reported.

  13. Synergistic antibacterial effects of treatments with low temperature plasma jet and pulsed electric fields

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Zhuang, Jie; von Woedtke, Thomas; Kolb, Juergen F.; Zhang, Jue; Fang, Jing; Weltmann, Klaus-Dieter

    2014-09-01

    Inactivation of Staphylococcus aureus by a non-thermal argon operated plasma jet and by microsecond pulsed electric fields (PEF) was investigated. The different methods were either applied by themselves or in combination with each other. Treatments with plasma alone or pulsed electric fields alone were found to result in significant but not complete inactivation. A 2-log reduction was observed for the longest plasma exposure time of 3 min or for the application of 300 consecutive electric field pulses with 100-μs duration and 15-kV/cm amplitude. For the combined treatment with non-thermal plasma and pulsed electric fields, significant synergistic antibacterial effects were observed when samples were treated with plasma first. However, only an additive or at most a slight synergistic effect was observed when samples were first treated with pulsed electric fields instead. The acidification of the bacteria suspension after plasma treatment is likely responsible for the support of subsequent reaction mechanisms that are induced by exposures to pulsed electric fields and is hence the reason for the observed synergy.

  14. Summarizing results on the performance of a selective set of atmospheric plasma jets for separation of photons and reactive particles

    NASA Astrophysics Data System (ADS)

    Schneider, Simon; Jarzina, Fabian; Lackmann, Jan-Wilm; Golda, Judith; Layes, Vincent; Schulz-von der Gathen, Volker; Bandow, Julia Elisabeth; Benedikt, Jan

    2015-11-01

    A microscale atmospheric-pressure plasma jet is a remote plasma jet, where plasma-generated reactive particles and photons are involved in substrate treatment. Here, we summarize our efforts to develop and characterize a particle- or photon-selective set of otherwise identical jets. In that way, the reactive species or photons can be used separately or in combination to study their isolated or combined effects to test whether the effects are additive or synergistic. The final version of the set of three jets—particle-jet, photon-jet and combined jet—is introduced. This final set realizes the highest reproducibility of the photon and particle fluxes, avoids turbulent gas flow, and the fluxes of the selected plasma-emitted components are almost identical in the case of all jets, while the other component is effectively blocked, which was verified by optical emission spectroscopy and mass spectrometry. Schlieren-imaging and a fluid dynamics simulation show the stability of the gas flow. The performance of these selective jets is demonstrated with the example of the treatment of E. coli bacteria with the different components emitted by a He-only, a He/N2 and a He/O2 plasma. Additionally, measurements of the vacuum UV photon spectra down to the wavelength of 50 nm can be made with the photon-jet and the relative comparison of spectral intensities among different gas mixtures is reported here. The results will show that the vacuum UV photons can lead to the inactivation of the E.coli bacteria.

  15. PLASMA JETS AND ERUPTIONS IN SOLAR CORONAL HOLES: A THREE-DIMENSIONAL FLUX EMERGENCE EXPERIMENT

    SciTech Connect

    Moreno-Insertis, F.

    2013-07-01

    A three-dimensional (3D) numerical experiment of the launching of a hot and fast coronal jet followed by several violent eruptions is analyzed in detail. These events are initiated through the emergence of a magnetic flux rope from the solar interior into a coronal hole. We explore the evolution of the emerging magnetically dominated plasma dome surmounted by a current sheet and the ensuing pattern of reconnection. A hot and fast coronal jet with inverted-Y shape is produced that shows properties comparable to those frequently observed with EUV and X-ray detectors. We analyze its 3D shape, its inhomogeneous internal structure, and its rise and decay phases, lasting for some 15-20 minutes each. Particular attention is devoted to the field line connectivities and the reconnection pattern. We also study the cool and high-density volume that appears to encircle the emerged dome. The decay of the jet is followed by a violent phase with a total of five eruptions. The first of them seems to follow the general pattern of tether-cutting reconnection in a sheared arcade, although modified by the field topology created by the preceding reconnection evolution. The two following eruptions take place near and above the strong-field concentrations at the surface. They show a twisted, {Omega}-loop-like rope expanding in height, with twist being turned into writhe, thus hinting at a kink instability (perhaps combined with a torus instability) as the cause of the eruption. The succession of a main jet ejection and a number of violent eruptions that resemble mini-CMEs and their physical properties suggest that this experiment may provide a model for the blowout jets recently proposed in the literature.

  16. Effects of a Nonthermal Atmospheric Pressure Plasma Jet on Human Gingival Fibroblasts for Biomedical Application

    PubMed Central

    2016-01-01

    Nonthermal atmospheric pressure plasma jets (APPJ) have been developed and applied in biomedical research as a cancer treatment or bacterial sterilization. However, the drawback of APPJ on normal oral cells during plasma treatment and underlying cell death mechanisms have not been studied and clearly explained, although there is known to be an influence from reactive oxygen species (ROS). Hence, this study investigates whether and how a nonthermal atmospheric pressure air plasma jet kills human normal gingival cells using immortalized human gingival fibroblasts (hTERT-hNOF cells). In this study, a set of physicochemical or biological methods were used to illuminate the killing mechanisms. It was found that ROS were induced intracellularly without a breakdown of the cell wall and apoptosis was involved in cell death when an air APPJ treatment was performed on the cells directly without media; the air treatment only supported a detachment of the cells without increase of ROS. It was also revealed that a correlation between intracellular ROS concentration and cells viability existed. These results indicated that the direct air APPJ treatment possibly raises safety issue to normal tissue and thereby APPJ application in biomedical field needs more in vitro and in vivo study to optimize it. PMID:27597959

  17. Time resolved mass spectrometry of positive ions originated from atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Selakovic, Nenad; Puac, Nevena; Maletic, Dejan; Malovic, Gordana; Petrovic, Zoran Lj.

    2013-09-01

    We present time-resolved measurements of positive ions originated from the atmospheric pressure plasma jet (APPJ) by using HIDEN HPR60 mass energy analyzer. APPJ was made of Pyrex glass tube with two transparent electrodes (15 mm wide PET foil). The gap between the electrodes was 15 mm, excitation frequency 80 kHz and applied voltage 6-10 kVpeak - to - peak. Helium flow rate was kept constant at 4 slm. In all measurements the distance between the plasma source and mass spectrometer orifice was 15 mm. Spectrometer detector gating was synchronized with the applied current and voltage signals in order to track in time the signal of detected ions. The internal gate width of HPR60 analyzer was 0.1 μs. We performed time resolved mass spectrometry of most abundant ion species originated from plasma jet: N2+(36%),N+(20%), O2+(18.5%),O+(16.8%), H2O+(6.1%), OH+, NO+, N2H+ and Ar+ (a few percentage). Results have shown that maximum intensity of nitrogen ions is lagging the maximum of current and voltage signal and maximum intensity for oxygen species is in opposite phase with current-voltage signals. Supported by MESTD, RS, III41011 and ON171037.

  18. Influence of discharge and jet flow coupling on atmospheric pressure plasma homogeneity

    NASA Astrophysics Data System (ADS)

    Nizard, H.; Gaudy, T.; Toutant, A.; Iacono, J.; Descamps, P.; Leempoel, P.; Massines, F.

    2015-10-01

    The effect of flow dynamics on the discharge mode is studied in order to design a technical solution for thin film coating on large surfaces. The configuration consists in two atmospheric pressure helium plasma jets impacting a surface and confined in a tube. This system operates in open air. It has been studied by short exposure time pictures, current and voltage measurements, optical emission spectroscopy, schlieren flow visualization and computational fluid dynamics. Two discharge regimes directly connected to the gas flow dynamic have been pointed out. One is localized from the point electrodes to the surface; the other one entirely fills the confinement tube. A correlation between air intake inside the confinement tube and the discharge mode has been highlighted. Indeed, the discharge only develops in helium and the air intake confines the helium jets in volumes smaller than the confinement tube. The air intake is determined by the gas flow rate and the distance from the tube bottom to the substrate surface, parameters which have been linked to the change from laminar to turbulent flow. Finally, the understanding of flow dynamics and discharge plasma coupling allowed the design of a technical solution favoring plasma homogeneity for large surface treatment.

  19. Effects of a Nonthermal Atmospheric Pressure Plasma Jet on Human Gingival Fibroblasts for Biomedical Application.

    PubMed

    Lee, Jung-Hwan; Kim, Kyoung-Nam

    2016-01-01

    Nonthermal atmospheric pressure plasma jets (APPJ) have been developed and applied in biomedical research as a cancer treatment or bacterial sterilization. However, the drawback of APPJ on normal oral cells during plasma treatment and underlying cell death mechanisms have not been studied and clearly explained, although there is known to be an influence from reactive oxygen species (ROS). Hence, this study investigates whether and how a nonthermal atmospheric pressure air plasma jet kills human normal gingival cells using immortalized human gingival fibroblasts (hTERT-hNOF cells). In this study, a set of physicochemical or biological methods were used to illuminate the killing mechanisms. It was found that ROS were induced intracellularly without a breakdown of the cell wall and apoptosis was involved in cell death when an air APPJ treatment was performed on the cells directly without media; the air treatment only supported a detachment of the cells without increase of ROS. It was also revealed that a correlation between intracellular ROS concentration and cells viability existed. These results indicated that the direct air APPJ treatment possibly raises safety issue to normal tissue and thereby APPJ application in biomedical field needs more in vitro and in vivo study to optimize it. PMID:27597959

  20. Optimizing Pulse Waveforms in Plasma Jets for Reactive Oxygen Species (ROS) Production

    NASA Astrophysics Data System (ADS)

    Norberg, Seth; Babaeva, Natalia Yu.; Kushner, Mark J.

    2012-10-01

    Reactive oxygen species (ROS) are desired in numerous applications from the destruction of harmful proteins and bacteria for sterilization in the medical field to taking advantage of the metastable characteristics of O2(^1δ) to transfer energy to other species. Advances in atmospheric pressure plasma jets in recent years show the possibility of using this application as a source of reactive oxygen species. In this paper, we report on results from a computational investigation of atmospheric pressure plasma jets in a dielectric barrier discharge (DBD) configuration. The computer model used in this study, nonPDPSIM, solves transport equations for charged and neutral species, Poisson's equation for the electric potential, the electron energy conservation equation for the electron temperature, and Navier-Stokes equations for the neutral gas flow. A Monte Carlo simulation is used to track sheath accelerated secondary electrons emitted from surfaces and the energy of ions incident onto surfaces. Rate coefficients and transport coefficients for the bulk plasma are obtained from local solutions of Boltzmann's equation for the electron energy distribution. Radiation transport is addressed using a Green's function approach. Various waveforms for the voltage source were examined in analogy to spiker-sustainer systems used at lower gas pressures.

  1. Nonequilibrium atmospheric pressure plasma jet using a combination of 50 kHz/2 MHz dual-frequency power sources

    SciTech Connect

    Zhou, Yong-Jie; Yuan, Qiang-Hua; Li, Fei; Wang, Xiao-Min; Yin, Gui-Qin; Dong, Chen-Zhong

    2013-11-15

    An atmospheric pressure plasma jet is generated by dual sinusoidal wave (50 kHz and 2 MHz). The dual-frequency plasma jet exhibits the advantages of both low frequency and radio frequency plasmas, namely, the long plasma plume and the high electron density. The radio frequency ignition voltage can be reduced significantly by using dual-frequency excitation compared to the conventional radio frequency without the aid of the low frequency excitation source. A larger operating range of α mode discharge can be obtained using dual-frequency excitation which is important to obtain homogeneous and low-temperature plasma. A larger controllable range of the gas temperature of atmospheric pressure plasma could also be obtained using dual-frequency excitation.

  2. Spectroscopic measurements of the parameters of the helium plasma jets generated in the plasma focus discharge at the PF-3 facility

    NASA Astrophysics Data System (ADS)

    Ananyev, S. S.; Dan'ko, S. A.; Myalton, V. V.; Zhuzhunashvili, A. I.; Kalinin, Yu. G.; Krauz, V. I.; Ladygina, M. S.; Marchenko, A. K.

    2016-03-01

    The spectroscopic technique used to measure the parameters of the plasma jets generated in the plasma focus discharge and those of the plasma of the immobile gas through which these jets propagate is described. The time evolution of the intensities and shapes of spectral lines in experiments carried out with helium at the PF-3 facility was studied by means of electron-optical streak cameras. The plasma electron temperature, T ≈ 4-5 eV, was determined from the intensity ratio of two spectral lines, one of which (λ1 = 5876 Å) belongs to neutral helium, while the other (λ2 = 4686 Å), to hydrogen-like helium ions. The plasma density at different time instants was determined from the Stark broadening of these lines in the electric fields of different nature. The plasma density is found to vary from 4 × 1014 to 2 × 1017 cm-3.

  3. Plasma-surface interaction in the Be/W environment: Conclusions drawn from the JET-ILW for ITER

    NASA Astrophysics Data System (ADS)

    Brezinsek, S.

    2015-08-01

    The JET ITER-Like Wall experiment (JET-ILW) provides an ideal test bed to investigate plasma-surface interaction (PSI) and plasma operation with the ITER plasma-facing material selection employing beryllium in the main chamber and tungsten in the divertor. The main PSI processes: material erosion and migration, (b) fuel recycling and retention, (c) impurity concentration and radiation have be1en studied and compared between JET-C and JET-ILW. The current physics understanding of these key processes in the JET-ILW revealed that both interpretation of previously obtained carbon results (JET-C) and predictions to ITER need to be revisited. The impact of the first-wall material on the plasma was underestimated. Main observations are: (a) low primary erosion source in H-mode plasmas and reduction of the material migration from the main chamber to the divertor (factor 7) as well as within the divertor from plasma-facing to remote areas (factor 30 - 50). The energetic threshold for beryllium sputtering minimises the primary erosion source and inhibits multi-step re-erosion in the divertor. The physical sputtering yield of tungsten is low as 10-5 and determined by beryllium ions. (b) Reduction of the long-term fuel retention (factor 10 - 20) in JET-ILW with respect to JET-C. The remaining retention is caused by implantation and co-deposition with beryllium and residual impurities. Outgassing has gained importance and impacts on the recycling properties of beryllium and tungsten. (c) The low effective plasma charge (Zeff = 1.2) and low radiation capability of beryllium reveal the bare deuterium plasma physics. Moderate nitrogen seeding, reaching Zeff = 1.6 , restores in particular the confinement and the L-H threshold behaviour. ITER-compatible divertor conditions with stable semi-detachment were obtained owing to a higher density limit with ILW. Overall JET demonstrated successful plasma operation in the Be/W material combination and confirms its advantageous PSI behaviour

  4. Laboratory Study of the Shaping and Evolution of Magnetized Episodic Plasma Jets

    NASA Astrophysics Data System (ADS)

    Higginson, Drew

    2015-11-01

    The expansion of hot, dense plasma (100 eV, 1018 cm-3) into vacuum occupied by a strong magnetic field (β =Pkinetic /Pmag ~ 1) along the expansion axis is a seemingly elementary physics problem, yet it is one that has scarcely been investigated. As well as being a fundamental problem in plasma physics, understanding such a situation is important to provide an explanation of large-scale jets observed in the formation of young stellar objects (YSO). Additionally, the ability to manipulate such a situation (e.g. to optimize x-ray emission) may be essential to the feasibility of recently proposed inertial confinement fusion (ICF) schemes with an imposed magnetic field. To investigate these situations, a CF2 foil is irradiated with the ELFIE laser (1013 W/cm2, 0.6 ns) in an external axial magnetic field of 20 T. As the plasma expands radially it is restricted by magnetic pressure that creates a cavity with a shock at the expansion edge. This shock redirects flow back on axis and creates a strong, stationary, conical shock that collimates the flow into a jet traveling over 1000 km/s and extending many centimeters. The effect of episodic heating (e.g. from variable mass ejection in a YSO, or pulse shaping in ICF) was investigated by irradiating the target with a precursor laser (1012 W/cm2, 0.6 ns) at 9 to 19 ns prior to the main pulse. The addition of this relatively small addition of energy (<20% of the main pulse energy) changed the dynamics of the expansion dramatically by increasing the strength of the conical shock, reducing the forward expansion of the cavity and dramatically increasing emission. We also present MHD simulations that reproduce the experimental observables and help to understand dynamics of jet and cavity formation. Prepared by LLNL under Contract DE-AC52-07NA27344. Presently at Lawrence Livermore National Laboratory.

  5. Observations of multiple stationary striation phenomena in an atmospheric pressure neon plasma jet

    NASA Astrophysics Data System (ADS)

    Fujiwara, Yutaka; Sakakita, Hajime; Yamada, Hiromasa; Yamagishi, Yusuke; Itagaki, Hirotomo; Kiyama, Satoru; Fujiwara, Masanori; Ikehara, Yuzuru; Kim, Jaeho

    2016-01-01

    The formation of multiple stationary striations between a nozzle exit and a conductive target plate was clearly observed at regular intervals using a digital camera along an atmospheric pressure plasma jet of dielectric barrier discharge using a neon gas into ambient air. From the results of measuring using a high-speed camera during the positive current phase, the emission initially started in the middle between the nozzle and the target, and striations progressed in both upward and downward directions. During the negative current phase, the emission initially started in a region near the target, and the striations rapidly progressed to the nozzle.

  6. Synthesis of silane and silicon in a non-equilibrium plasma jet

    NASA Technical Reports Server (NTRS)

    Calcote, H. F.; Felder, W.

    1977-01-01

    The feasibility of using a non-equilibrium hydrogen plasma jet as a chemical synthesis tool was investigated. Four possible processes were identified for further study: (1) production of polycrystalline silicon photovoltaic surfaces, (2) production of SiHCl3 from SiCl4, (3) production of SiH4 from SiHCl3, and (4) purification of SiCl4 by metal impurity nucleation. The most striking result was the recognition that the strongly adhering silicon films, amorphous or polycrystalline, produced in our studies could be the basis for preparing a photovoltaic surface directly; this process has potential advantages over other vapor deposition processes.

  7. Microturbulence and Flow Shear in High-performance JET ITB Plasma

    SciTech Connect

    R.V. Budny; A. Andre; A. Bicoulet; C. Challis; G.D. Conway; W. Dorland; D.R. Ernst; T.S. Hahm; T.C. Hender; D. McCune; G. Rewoldt; S.E. Sharapov

    2001-12-05

    The transport, flow shear, and linear growth rates of microturbulence are studied for a Joint European Torus (JET) plasma with high central q in which an internal transport barrier (ITB) forms and grows to a large radius. The linear microturbulence growth rates of the fastest growing (most unstable) toroidal modes with high toroidal mode number are calculated using the GS2 and FULL gyrokinetic codes. These linear growth rates, gamma (subscript lin) are large, but the flow-shearing rates, gamma (subscript ExB) (dominated by the toroidal rotation contribution) are also comparably large when and where the ITB exists.

  8. Direct observation of grain growth from molten silicon formed by micro-thermal-plasma-jet irradiation

    PubMed Central

    Hayashi, Shohei; Fujita, Yuji; Kamikura, Takahiro; Sakaike, Kohei; Akazawa, Muneki; Ikeda, Mitsuhisa; Hanafusa, Hiroaki; Higashi, Seiichiro

    2012-01-01

    Phase transformation of amorphous-silicon during millisecond annealing using micro-thermal-plasma-jet irradiation was directly observed using a high-speed camera with microsecond time resolution. An oval-shaped molten-silicon region adjacent to the solid phase crystallization region was clearly observed, followed by lateral large grain growth perpendicular to a liquid-solid interface. Furthermore, leading wave crystallization (LWC), which showed intermittent explosive crystallization, was discovered in front of the moving molten region. The growth mechanism of LWC has been investigated on the basis of numerical simulation implementing explosive movement of a thin liquid layer driven by released latent heat diffusion in a lateral direction. PMID:23185095

  9. Interactions Between Small Arrays of Atmospheric Pressure Micro-Plasma Jets: Gas Dynamic, Radiation and Electrostatic Interactions

    NASA Astrophysics Data System (ADS)

    Babaeva, Natalia

    2013-09-01

    Atmospheric pressure plasma jets are widely used devices for biomedical applications. A typical plasma jet consists of a tube through which noble gas or its mixture with a molecular gas flows. The noble gas creates a channel into the ambient air which is eventually dispersed by interdiffusion with the air. Plasma plumes are formed by the propagation of ionization waves (IWs) through the tubes and then through the noble gas phase channel. The IW typically propagates until the mole fraction of the ambient air in the channel increases above a critical values which requires a larger E/N to propagate the IW. By grouping several jets together to form an array of jets, one can in principle increase the area treated by the plume. If the jets are sufficiently far apart, the IWs and resulting plasma plumes are independent. As the spacing between the jets decreases, the plasma jets begin to mutually interact. In this talk, we discuss results from a computational investigation of small arrays of He/O2 micro-plasma jets propagating into ambient air. The model used in this work, nonPDPSIM, is a plasma hydrodynamics model in which continuity, momentum and energy equations are solved for charged and neutral species with solution of Poisson's equation for the electric potential. Navier-Stokes equations are solved for the gas dynamics and radiation transport is addressed using a propagator method. We found that as the spacing between the jets decreases, the He channels from the individual jets tend to merge. The IWs from each channel also merge into regions having the highest He mole fraction and so lowest E/N to sustain the IW. The proximity of the IWs enable other forms of interaction. If the IWs are of the same polarity, electrostatic forces can warp the paths of the IWs. If in sufficient proximity, the photoionization from one IW can influence its neighbors. The synchronization of the voltage pulses of adjacent IWs can also influence its neighbors. With synchronized pulses

  10. Synthesis of highly transparent ultrananocrystalline diamond films from a low-pressure, low-temperature focused microwave plasma jet

    PubMed Central

    2012-01-01

    This paper describes a new low-temperature process underlying the synthesis of highly transparent ultrananocrystalline diamond [UNCD] films by low-pressure and unheated microwave plasma jet-enhanced chemical vapor deposition with Ar-1%CH4-10%H2 gas chemistry. The unique low-pressure/low-temperature [LPLT] plasma jet-enhanced growth even with added H2 and unheated substrates yields UNCD films similar to those prepared by plasma-enhanced growth without addition of H2 and heating procedure. This is due to the focused plasma jet which effectively compensated for the sluggish kinetics associated with LPLT growth. The effects of pressure on UNCD film synthesis from the microwave plasma jet were systematically investigated. The results indicated that the substrate temperature, grain size, surface roughness, and sp3 carbon content in the films decreased with decreasing pressure. The reason is due to the great reduction of Hα emission to lower the etching of sp2 carbon phase, resulting from the increase of mean free path with decreasing pressure. We have demonstrated that the transition from nanocrystalline (80 nm) to ultrananocrystalline (3 to 5 nm) diamond films grown via microwave Ar-1%CH4-10%H2 plasma jets could be controlled by changing the pressure from 100 to 30 Torr. The 250-nm-thick UNCD film was synthesized on glass substrates (glass transition temperature [Tg] 557°C) using the unique LPLT (30 Torr/460°C) microwave plasma jet, which produced UNCD films with a high sp3 carbon content (95.65%) and offered high optical transmittance (approximately 86% at 700 nm). PMID:22260391

  11. Laser scattering diagnostics of an argon atmospheric-pressure plasma jet in contact with vaporized water

    NASA Astrophysics Data System (ADS)

    Seo, B. H.; Kim, J. H.; You, S. J.; Seong, D. J.

    2015-12-01

    The radial profiles of the electron density, electron temperature, and molecular rotational temperature are investigated in an argon atmospheric-pressure plasma jet in contact with vaporized water, which is driven by a 13.56 MHz radio frequency by means of the Thomson and Raman laser scattering methods. There is a distinct difference in the radial profiles of the plasma parameters between plasmas in contact with water and those without water contact. In the case of plasmas without vaporized water contact, all the parameters have a single-peak distribution with maximum values at the center of the discharge. In the case of plasmas in contact with vaporized water, all parameters have double-peak distributions; a neighboring peak appears beside the main peak. The new peak may have originated from the ripple of the water surface, which works as a cathode, and the peak of the ripple offers a sharp curvature point, playing the role of a pin. Our experimental results and the underlying physics are described in detail.

  12. DNA damage in oral cancer and normal cells induced by nitrogen atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Han, Xu; Kapaldo, James; Liu, Yueying; Stack, M. Sharon; Ptasinska, Sylwia

    2015-09-01

    Nitrogen atmospheric pressure plasma jets (APPJs) have been shown to effectively induce DNA double strand breaks in SCC25 oral cancer cells. The APPJ source constructed in our laboratory operates based on dielectric barrier discharge. It consists of two copper electrodes alternatively wrapping around a fused silica tube with nitrogen as a feed gas. It is generally more challenging to ignite plasma in N2 atmosphere than in noble gases. However, N2 provides additional advantages such as lower costs compared to noble gases, thus this design can be beneficial for the future long-term clinical use. To compare the effects of plasma on cancer cells (SCC25) and normal cells (OKF), the cells from both types were treated at the same experimental condition for various treatment times. The effective area with different damage levels after the treatment was visualized as 3D maps. The delayed damage effects were also explored by varying the incubation times after the treatment. All of these studies are critical for a better understanding of the damage responses of cellular systems exposed to the plasma radiation, thus are useful for the development of the advanced plasma cancer therapy. The research described herein was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Basic Energy Sciences, Office of Science, United States Department of Energy through Grant No. DE-FC02-04ER15533.

  13. Decontamination of chemical and biological warfare (CBW) agents using an atmospheric pressure plasma jet (APPJ)

    SciTech Connect

    Herrmann, H.W.; Henins, I.; Park, J.; Selwyn, G.S.

    1999-05-01

    The atmospheric pressure plasma jet (APPJ) [A. Sch{umlt u}tze {ital et al.}, IEEE Trans. Plasma Sci. {bold 26}, 1685 (1998)] is a nonthermal, high pressure, uniform glow plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He/O{sub 2}/H{sub 2}O), which flows between an outer, grounded, cylindrical electrode and an inner, coaxial electrode powered at 13.56 MHz rf. While passing through the plasma, the feedgas becomes excited, dissociated or ionized by electron impact. Once the gas exits the discharge volume, ions and electrons are rapidly lost by recombination, but the fast-flowing effluent still contains neutral metastable species (e.g., O{sub 2}{sup {asterisk}}, He{sup {asterisk}}) and radicals (e.g., O, OH). This reactive effluent has been shown to be an effective neutralizer of surrogates for anthrax spores and mustard blister agent. Unlike conventional wet decontamination methods, the plasma effluent does not cause corrosion and it does not destroy wiring, electronics, or most plastics, making it highly suitable for decontamination of sensitive equipment and interior spaces. Furthermore, the reactive species in the effluent rapidly degrade into harmless products leaving no lingering residue or harmful by-products. {copyright} {ital 1999 American Institute of Physics.}

  14. Interaction of DC Microhollow Cathode Discharge Plasma Micro Jet with Liquid Media

    NASA Astrophysics Data System (ADS)

    Zhu, Weidong; Lopez, Jose; Becker, Kurt

    2008-10-01

    There have been different approaches in studying the interaction between plasma and liquid, such as sustained plasmas in contact with liquids and pulsed electric discharge in liquids. Recently, we have discovered that stable plasma can be sustained within a gas cavity maintained inside liquid media. A prototype device with key dimensions in sub-millimeter range were operated successfully in de-ionized water and turbo molecular pump oil with ambient air, pure nitrogen or pure oxygen used as the operating gas. Hydrogen Peroxide production in de-ionized water with ambient air as the working gas is estimated to be about 80 mg/L after 15 minutes plasma jet-water interaction while energy consumption is only about 8-10 W. With the radicals readily generated and directly introduced into the liquid media, it could lead to applications such as in-liquid bio-waste treatment, bio-rich liquid modification, in-situ monitoring/sensing, and filtration of by-products from VOC treatment by plasma.

  15. Comparison of Carbon and Main Ion Radiation Profiles in Matched Helium and Deuterium Plasmas in JET

    SciTech Connect

    Fenstermacher, M E; Lawson, K D; Porter, G D; Erents, S K; Ingesson, C; Mathews, G F; McCracken, G M; Philipps, V; Pitts, A; Stamp, M F

    2002-05-17

    This paper examines the radiation profiles and corresponding ionization source profiles of various carbon and main plasma ions in matched helium and deuterium L-mode plasmas in JET. Operation in helium should reduce chemical sputtering of carbon substantially compared with deuterium. The radiation intensities from C{sup 1+}, C{sup 2+} and C{sup 3+} in the helium plasmas showed reduction by factors of 8, 10 and 25 respectively along the inner SOL and divertor leg compared with the deuterium cases. However, the emission in the outer divertor leg was less than a factor of 2 lower in helium. Using photon efficiencies calculated by the UEDGE code for the spectrometer lines of sight, the calculated source rates of C{sup 1+} and C{sup 3+} along the inner SOL and inner divertor were reduced by a factors of 4 and 20 respectively in the helium plasmas. In the outer divertor leg the source rate of C{sup 3+} was reduced by a factor of 10 but the C{sup 1+} source rate did not change in helium. These measurements are consistent with a model that chemical sputtering of carbon dominates the source from the inner wall and inner divertor in deuterium L-mode plasmas while physical sputtering appears to dominate the source from the outer divertor.

  16. Local deposition of SiOx plasma polymer films by a miniaturized atmospheric pressure plasma jet (APPJ)

    NASA Astrophysics Data System (ADS)

    Schäfer, J.; Foest, R.; Quade, A.; Ohl, A.; Weltmann, K.-D.

    2008-10-01

    An atmospheric plasma jet (APPJ, 27.17 MHz, Ar with 1% HMDSO) has been studied for the deposition of thin silicon-organic films. Jet geometries are attractive for local surface treatment or for conformal covering of 3D forms, e.g. inner walls of wells, trenches or cavities, because they are not confined by electrodes and their dimensions can be varied from several centimetres down to the sub-millimetre region. Deposition experiments have been performed on flat polymer and glass samples with a deposition rate of 0.25-23 nm s-1. The knowledge of the static deposition profile of the plasma source (footprint) is essential to allow for a controlled deposition with the source moving relative to the substrate. By adjusting the plasma parameters (RF power and gas flow) to the geometry (i.e. electrode configuration, tube diameter, relative tube position, substrate distance) the footprint can be shaped from a ring form reflecting the tube dimension to a parabolic profile. Next to the conventional stochastic mode of operation we observe a characteristic locked mode—reported here for the first time for an RF-APPJ which can improve the film deposition process distinctively. The experimental results of the local film distribution agree well with an analytical model of the deposition kinetics. The film properties have been evaluated (profilometry, XPS, FT-IR spectroscopy and SEM) for different deposition conditions and substrate distance. The FT-IR spectra demonstrate dominating SiO absorption bands, thus providing an indication for the prevailing (inorganic) SiOx character of the films. HMDSO molecules disintegrate to a sufficient degree as proved by the absence of CH2 absorption in the spectra. XPS measurements confirm the local dependence with a slightly increased organic character a few millimetres away from the maximum in the deposition profile. The substrate distance and the source direction both seem relevant and require consideration during coating of 3D objects.

  17. Exploring Hadron Production from Jets and Quark Gluon Plasma at LHC

    NASA Astrophysics Data System (ADS)

    Jinkins, Katherine

    2013-10-01

    QCD jets are sprays of hadrons created from a quark or gluon at high energy. Hadrons from jets dominate the hadron spectrum above transverse momenta PT ~ 5-8 GeV/c in ultra-relativistic heavy ion collisions at RHIC and LHC. At smaller momenta, below PT ~ 2 GeV/c, hadron production is well described by hydrodynamics or blast-wave models assuming thermalization, while between 2 and 5 GeV/c hadron production proceeds through quark recombination of an off-equilibrium quark gluon plasma. We improved the jet quenching code PPM to describe the high-momentum hadron data recently published by the ALICE experiment at the LHC. PPM Glauber calculations of the transverse densities of nucleons participating in collisions, and the overall number of participants and collisions (Npart and Ncoll, respectively) were updated by changing the previous hard sphere approximation of a nucleus to Woods-Saxon profiles. Impact parameters were matched to centrality bins published by the ALICE experiment. Using the sLPM (Landau-Pomeranchuk-Migdal effect) energy loss model for partons in PPM, the energy loss parameter csLPM = qhat/s was adjusted to achieve a consistent description of high momentum ALICE data. A blast wave model calculation at low momentum was also added to achieve a comprehensive fit to ALICE data. Funded by NSF REU Program.

  18. Neutron spectroscopy results of JET high-performance plasmas and extrapolations to DT performance.

    PubMed

    Hellesen, C; Andersson Sundén, E; Conroy, S; Ericsson, G; Eriksson, J; Gatu Johnson, M; Weiszflog, M

    2010-10-01

    In a fusion reactor with high energy gain, the fusion power will be mainly thermonuclear (THN). Measurements of the THN neutron rate are a good performance indicator of a fusion plasma, requiring neutron emission spectroscopy (NES) measurements to distinguish thermal and nonthermal contributions. We report here on recent NES results from JET high-performance plasmas with high fractions (about 65%) of THN emission. The analysis is made with a framework for analyzing NES data, taking into account THN reactions and beam-target reactions. The results are used to extrapolate to the equivalent DT rates. Finally, we discuss the applicability of using NES in the deuterium phase of ITER, both for the extrapolations to ITER’s future DT performance as well as for the measurements of confined energetic ions. PMID:21058461

  19. Characterization of a DBD-Based Plasma Jet Using a Variable Pulse Width Nanosecond Pulser

    NASA Astrophysics Data System (ADS)

    Ziemba, Timothy; Picard, Julian; Prager, James; Miller, Kenneth; Carscadden, John

    2015-11-01

    Most high voltage pulsers used to drive dielectric barrier discharges (DBDs), produce a single pulse shape (width and voltage), thus making it challenging to assess the effect of pulse shape on the production of different chemical species during a discharge. Eagle Harbor Technologies, Inc. (EHT) has developed a high voltage nanosecond pulser that enables independent control of the output voltage, pulse width, and pulse repetition frequency. This pulser has been specifically designed to drive dielectric barrier discharges (DBD). EHT has used this pulser to conduct a parametric investigation of a DBD-based jet utilizing spectroscopic diagnostics. A better understanding of this parameter dependency can allow for more targeted and effective application of plasma in medical, environmental, industrial, and other applications. Results comparing DBD voltage and current waveforms with plasma spectrographic measurements will be presented.

  20. Gas mixing enhanced by power modulations in atmospheric pressure microwave plasma jet

    NASA Astrophysics Data System (ADS)

    Voráč, J.; Potočňáková, L.; Synek, P.; Hnilica, J.; Kudrle, V.

    2016-04-01

    Microwave plasma jet operating in atmospheric pressure argon was power modulated by audio frequency sine envelope in the 102 W power range. Its effluent was imaged using interference filters and ICCD camera for several different phases of the modulating signal. The combination of this fast imaging with spatially resolved optical emission spectroscopy provides useful insights into the plasmachemical processes involved. Phase-resolved schlieren photography was performed to visualize the gas dynamics. The results show that for higher modulation frequencies the plasma chemistry is strongly influenced by formation of transient flow perturbation resembling a vortex during each period. The perturbation formation and speed are strongly influenced by the frequency and power variations while they depend only weakly on the working gas flow rate. From application point of view, the perturbation presence significantly broadened lateral distribution of active species, effectively increasing cross-sectional area suitable for applications.

  1. Neutron spectroscopy results of JET high-performance plasmas and extrapolations to DT performance

    SciTech Connect

    Hellesen, C.; Andersson Sunden, E.; Conroy, S.; Ericsson, G.; Eriksson, J.; Gatu Johnson, M.; Weiszflog, M.; Collaboration: JET-EFDA Contributors

    2010-10-15

    In a fusion reactor with high energy gain, the fusion power will be mainly thermonuclear (THN). Measurements of the THN neutron rate are a good performance indicator of a fusion plasma, requiring neutron emission spectroscopy (NES) measurements to distinguish thermal and nonthermal contributions. We report here on recent NES results from JET high-performance plasmas with high fractions (about 65%) of THN emission. The analysis is made with a framework for analyzing NES data, taking into account THN reactions and beam-target reactions. The results are used to extrapolate to the equivalent DT rates. Finally, we discuss the applicability of using NES in the deuterium phase of ITER, both for the extrapolations to ITER's future DT performance as well as for the measurements of confined energetic ions.

  2. Atmospheric-pressure-plasma-jet sintered nanoporous AlN/CNT composites

    NASA Astrophysics Data System (ADS)

    Chiu, Yi-Fan; Yeh, Po-Wei; Cheng, I.-Chun; Chen, Jian-Zhang

    2016-07-01

    A nanoporous AlN-5 wt% CNT composite is successfully sintered using atmospheric-pressure plasma jets (APPJs). The AlN in an APPJ-sintered AlN/CNT composite shows a pure hexagonal [space group: P63mc] crystal structure. Optical emission spectroscopy (OES) results indicate that the CN violet emission intensity rapidly increases and then decreases owing to the vigorous interaction between the nitrogen APPJ and the carbonaceous materials in the printed pastes. Because the vigorous interaction may over-burn the CNTs, the conductivity of AlN first increases and then decreases as the APPJ sintering duration increases. APPJ-sintered AlN/CNT composites exhibit good CF4 inductively coupled plasma erosion resistant property.

  3. Progress in Development of C60 Nanoparticle Plasma Jet for Diagnostic of Runaway Electron Beam-Plasma Interaction and Disruption Mitigation Study for ITER

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Thompson, J. R.; Galkin, S. A.; Kim, J. S.

    2013-10-01

    We produced a C60 nanoparticle plasma jet (NPPJ) with uniquely fast response-to-delivery time (~ 1 - 2 ms) and unprecedentedly high momentum (~ 0 . 6 g .km/s). The C60 NPPJ was obtained by using a solid state TiH2/C60 pulsed power cartridge producing ~180 mg of C60 molecular gas by sublimation and by electromagnetic acceleration of the C60 plasma in a coaxial gun (~35 cm length, 96 kJ energy) with the output of a high-density (>1023 m-3) hyper-velocity (>4 km/s) plasma jet. The ~ 75 mg C60/C plasma jet has the potential to rapidly and deeply deliver enough mass to significantly increase electron density (to ne ~ 2 . 4 ×1021 m-3, i.e. ~ 60 times larger than typical DIII-D pre-disruption value, ne 0 ~ 4 ×1019 m-3), and to modify the 'critical electric field' and the runaway electrons (REs) collisional drag during different phases of REs dynamics. The C60 NPPJ, as a novel injection technique, allows RE beam-plasma interaction diagnostic by quantitative spectroscopy of C ions visible/UV line intensity. The system is scalable to ~ 1 - 2 g C60/C plasma jet output and technology is adaptable to ITER acceptable materials (BN and Be) for disruption mitigation. Work supported by US DOE DE-FG02-08ER85196 grant.

  4. Observation of inactivation of Bacillus sbtilis spores under exposures of oxygen added argon atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Shen, Jie; Cheng, Cheng; Zhao, Ying; Xiao, Dezhi; Lan, Yan; Xie, Hongbing; Cheng, Junli; Meng, Yuedong; Li, Jiangang; Chu, Paul K.

    2014-11-01

    The inactivation of Bacillus subtilis spores by an Ar plasma jet mixed with different amounts of oxygen is reported. 5.8 × 106 B. subtilis spores are sterilized by an Ar/O2 (8.7%) plasma jet after exposure for 2 min. The densities of ozone and oxygen radicals in the Ar/O2 plasma jet increase with oxygen concentration and are estimated by optical spectroscopy diagnostic. The malondialdehyde (MDA) test shows that oxygen radicals participate in bacterial inactivation. Scanning electron microscopy (SEM) reveals the deformation of the spore shape due to etching by oxygen radicals and the dependence of the degree of deformation on the density of oxygen radicals.

  5. Stark broadening measurement of the electron density in an atmospheric pressure argon plasma jet with double-power electrodes

    SciTech Connect

    Qian Muyang; Ren Chunsheng; Wang Dezhen; Zhang Jialiang; Wei Guodong

    2010-03-15

    Characteristics of a double-power electrode dielectric barrier discharge of an argon plasma jet generated at the atmospheric pressure are investigated in this paper. Time-averaged optical emission spectroscopy is used to measure the plasma parameters, of which the excitation electron temperature is determined by the Boltzmann's plot method whereas the gas temperature is estimated using a fiber thermometer. Furthermore, the Stark broadening of the hydrogen Balmer H{sub {beta}} line is applied to measure the electron density, and the simultaneous presence of comparable Doppler, van der Waals, and instrumental broadenings is discussed. Besides, properties of the jet discharge are also studied by electrical diagnosis. It has been found that the electron densities in this argon plasma jet are on the order of 10{sup 14} cm{sup -3}, and the excitation temperature, gas temperature, and electron density increase with the applied voltage. On the other hand, these parameters are inversely proportional to the argon gas flow rate.

  6. The Structure-Phase Compositions of Powder Ni - based Coatings after Modification by DC Plasma Jet Irradiation

    NASA Astrophysics Data System (ADS)

    Alontseva, D.; Ghassemieh, E.

    2015-10-01

    This paper presents the results of investigation of the structure-phase compositions of Ni-based coatings deposited by plasma jet on steel substrates after modification by direct current (DC) plasma jet irradiation. Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray Diffraction (XRD) are used in the current study. The phase structures and morphology of precipitation of strengthening phases from solid solution are defined. The irradiation of the coatings leads to the evolution of the structural-phase state of coatings: an increase in the volume fraction of hardening intermetallic phases, the formation of sufficiently homogeneous fine-grained structure in the irradiated coatings. There is a mutual penetration of the substrate main element Fe into the coating and base coating elements Ni into the substrate as a result of the coating treatment by a pulse DC plasma jet.

  7. Enthalpy probe measurements and three-dimensional modelling on air plasma jets generated by a non-transferred plasma torch with hollow electrodes

    NASA Astrophysics Data System (ADS)

    Kim, Keun Su; Park, Jin Myung; Choi, Sooseok; Kim, Jongin; Hong, Sang Hee

    2008-03-01

    Thermal flow characteristics of air plasma jets generated by a non-transferred plasma torch with hollow electrodes are experimentally and numerically investigated in order to provide more reliable scientific and technical information, which has been insufficient for their practical applications to material and environmental industries. In this work, a thermal plasma torch of hollow electrode type is first designed and fabricated, and similarity criteria for predicting operational conditions for the scale-up to high-power torches are derived from the arc voltage characteristics measured with various operating and geometry conditions of the torch. The thermal flow characteristics of air plasma jets ejected from the torch are measured by enthalpy probe diagnostics and turn out to have relatively low temperatures of around 3000-7000 K, but show features of other unique properties, such as high energy flux, broad high temperature region and long plasma jet with moderate axial velocity, which are promising for their applications to material syntheses and hazardous waste treatments. Such high enthalpy at a relatively low temperature of air thermal plasma compared with the argon one is due to the high thermal energy residing in the vibrational and rotational states and oxygen dissociation, besides the translational states in monatomic gases such as argon. It is expected that this high specific enthalpy of the air plasma will enable material and environmental industries to treat a large amount of precursors and waste materials effectively at a lower temperature for a longer residence time by the low plasma velocity. It is also found from the measurements that the turbulence intensity influenced by the size of the electrode diameter has a significant effect on the axial and radial profiles of plasma jet properties and that a longer plasma jet is more readily achievable with a larger electrode diameter reducing the turbulence intensity in the external region of the torch. In

  8. Inferring divertor plasma properties from hydrogen Balmer and Paschen series spectroscopy in JET-ILW

    NASA Astrophysics Data System (ADS)

    Lomanowski, B. A.; Meigs, A. G.; Sharples, R. M.; Stamp, M.; Guillemaut, C.; Contributors, JET

    2015-11-01

    A parametrised spectral line profile model is formulated to investigate the diagnostic scope for recovering plasma parameters from hydrogenic Balmer and Paschen series spectroscopy in the context of JET-ILW divertor plasmas. The separate treatment of Zeeman and Stark contributions in the line model is tested against the PPP-B code which accounts for their combined influence on the spectral line shape. The proposed simplified model does not fully reproduce the Stark-Zeeman features for the α and β transitions, but good agreement is observed in the line width and wing profiles, especially for n  >  5. The line model has been applied to infer radial density profiles in the JET-ILW divertor with generally good agreement between the D 5\\to 2 , 5\\to 3 , 6\\to 2 , 7\\to 2 and 9\\to 2 lines for high recycling and detached conditions. In an L-mode detached plasma pulse the Langmuir probe measurements typically underestimated the density by a factor 2-3 and overestimated the electron temperature by a factor of 5-10 compared to spectroscopically derived values. The line model is further used to generate synthetic high-resolution spectra for low-n transitions to assess the potential for parameter recovery using a multi-parametric fitting technique. In cases with 4 parameter fits with a single Maxwellian neutral temperature component the D 4\\to 3 line yields the best results with parameter estimates within 10% of the input values. For cases with 9 parameter fits inclusive of a multi-component neutral velocity distribution function the quality of the fits is degraded. Simultaneous fitting of the D 3\\to 2 and 4\\to 3 profiles improves the fit quality significantly, highlighting the importance of complementary spectroscopic measurements for divertor plasma emission studies.

  9. Partons and Jets in a Strongly-Coupled Plasma from AdS/CFT

    NASA Astrophysics Data System (ADS)

    Iancu, E.

    2008-12-01

    We give a pedagogical review of recent progress towards understanding the response of a strongly coupled plasma at finite temperature to a hard probe. The plasma is that of the N=4 supersymmetric Yang-Mills theory and the hard probe is a virtual photon, or, more precisely, an R-current. Via the gauge/gravity duality, the problem of the current interacting with the plasma is mapped onto the gravitational interaction between a Maxwell field and a black hole embedded in the AdS5×S5 geometry. The physical interpretation of the AdS/CFT results can be then reconstructed with the help of the ultraviolet/infrared correspondence. We thus deduce that, for sufficiently high energy, the photon (or any other hard probe: a quark, a gluon, or a meson) disappears into the plasma via a universal mechanism, which is medium-induced quasi-democratic parton branching: the current develops a parton cascade such that, at any step in the branching process, the energy is almost equally divided among the daughter partons. The branching rate is controlled by the plasma which acts on the coloured partons with a constant force sim T2. When reinterpreted in the plasma infinite momentum frame, the same AdS/CFT results suggest a parton picture for the plasma structure functions, in which all the partons have fallen at very small values of Bjorken's x. For a time-like current in the vacuum, quasi-democratic branching implies that there should be no jets in electron-positron annihilation at strong coupling, but only a spatially isotropic distribution of hadronic matter.

  10. A PHYSICAL LINK BETWEEN JET FORMATION AND HOT PLASMA IN ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Wu Qingwen; Wang Dingxiong; Cao Xinwu; Ho, Luis C. E-mail: dxwang@hust.edu.cn E-mail: lho@obs.carnegiescience.edu

    2013-06-10

    Recent observations suggest that in black hole X-ray binaries jet/outflow formation is related to the hot plasma in the vicinity of the black hole, either in the form of an advection-dominated accretion flow at low accretion rates or in a disk corona at high accretion rates. We test the viability of this scenario for supermassive black holes using two samples of active galactic nuclei distinguished by the presence (radio-strong) and absence (radio-weak) of well-collimated, relativistic jets. Each is centered on a narrow range of black hole mass but spans a very broad range of Eddington ratios, effectively simulating in a statistical manner the behavior of a single black hole evolving across a wide spread in accretion states. Unlike the relationship between the radio and optical luminosity, which shows an abrupt break between high- and low-luminosity sources at an Eddington ratio of {approx}1%, the radio emission-a measure of the jet power-varies continuously with the hard X-ray (2-10 keV) luminosity, roughly as L{sub R} {proportional_to} L{sub X}{sup 0.6-0.75}. This relation, which holds for both radio-weak and radio-strong active galaxies, is similar to the one seen in X-ray binaries. Jet/outflow formation appears to be closely linked to the conditions that give rise to the hot, optically thin coronal emission associated with accretion flows, both in the regime of low and high accretion rates.

  11. Dynamics of the gas flow turbulent front in atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Pei, X.; Ghasemi, M.; Xu, H.; Hasnain, Q.; Wu, S.; Tu, Y.; Lu, X.

    2016-06-01

    In this paper, dynamic characterizations of the turbulent flow field in atmospheric pressure plasma jets (APPJs) are investigated by focusing on the effect of different APPJ parameters, such as gas flow rate, applied voltage, pulse repetition frequency, and time duration of the pulse. We utilize Schlieren photography and photomultiplier tubes (PMT) as a signal triggering of an intensified charge coupled device (ICCD) and also a high speed camera to examine the formation of the turbulent front and its dynamics. The results reveal that the turbulent front will appear earlier and closer to the tube nozzle by increasing the gas flow rate or the applied voltage amplitude. However, the pulse time duration and repetition frequency cannot change the dynamics and formation of the turbulent front. Further investigation shows that every pulse can excite one turbulent front which is created in a specific position in a laminar region and propagates downstream. It seems that the dominating mechanisms responsible for the formation of turbulent fronts in plasma jets might not be ion momentum transfer.

  12. Nonequilibrium Atmospheric Pressure Ar/O2 Plasma Jet: Properties and Application to Surface Cleaning

    NASA Astrophysics Data System (ADS)

    Jin, Ying; Ren, Chunsheng; Yang, Liang; Zhang, Jialiang

    2016-02-01

    In this study an atmospheric pressure Ar/O2 plasma jet is generated to study the effects of applied voltage and gas flux rate to the behavior of discharge and the metal surface cleaning. The increase in applied voltage leads to increases of the root mean square (rms) current, the input power and the gas temperature. Furthermore, the optical emission spectra show that the emission intensities of metastable argon and atomic oxygen increase with increasing applied voltage. However, the increase in gas flux rate leads to a reduction of the rms current, the input power and the gas temperature. Furthermore, the emission intensities of metastable argon and atomic oxygen decrease when gas flux rate increases. Contact angles are measured to estimate the cleaning performance, and the results show that the increase of applied voltage can improve the cleaning performance. Nevertheless, the increase of gas flux rate cannot improve the cleaning performance. Contact angles are compared for different input powers and gas flux rates to search for a better understanding of the major mechanism for surface cleaning by plasma jets. supported by National Natural Science Foundation of China (No. 11305017)

  13. Characterization of an atmospheric helium plasma jet by relative and absolute optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Xiong, Qing; Nikiforov, Anton Yu; González, Manuel Á.; Leys, Christophe; Pei Lu, Xin

    2013-02-01

    The characteristics of plasma temperatures (gas temperature and electron excitation temperature) and electron density in a pulsed-dc excited atmospheric helium plasma jet are studied by relative and absolute optical emission spectroscopy (OES). High-resolution OES is performed for the helium and hydrogen lines for the determination of electron density through the Stark broadening mechanism. A superposition fitting method composed of two component profiles corresponding to two different electron densities is developed to fit the investigated lines. Electron densities of the orders of magnitude of 1021 and 1020 m-3 are characterized for the center and edge regions in the jet discharge when the applied voltage is higher than 13.0 kV. The atomic state distribution function (ASDF) of helium demonstrates that the discharge deviates from the Boltzmann-Saha equilibrium state, especially for the helium lower levels, which are significantly overpopulated. Local electron excitation temperatures T13 and Tspec corresponding to the lower and upper parts of the helium ASDF are defined and found to range from 1.2 eV to 1.4 eV and 0.2 eV to 0.3 eV, respectively. A comparative analysis shows that the Saha balance is valid in the discharge for helium atoms at high excited states.

  14. Effect on surface roughness of zerodur material in atmospheric pressure plasma jet processing

    NASA Astrophysics Data System (ADS)

    Jin, H. L.; Wang, B.; Zhang, F. H.

    2010-10-01

    Zerodur material is considered as the ideal material in the high performance optic systems because of its excellent thermal stability characteristics. This paper deals with the impacting factors on the zerodur material surface roughness during atmospheric pressure plasma jet(APPJ) processing. At first, based on multiphase and multi-component in zerodur material, the effect on the zerodur surface chemical components and surface roughness is studied when the element contained Si is etched during the chemical machining process. The change of surface microcosmic topography is observed, it is proved that the technology of atmospheric pressure plasma jet can modify the surface roughness of zerodur material. Moreover, in consideration of the re-deposition phenomenon in the machining process, the composition of the re-deposition are studied and the genesis of the re-deposition were analysed. Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray spectrometry (EDX) were utilized to obtain the elemental composition of the sample powder residuum on zerodur surface. The relationship between substrate roughness and the process parameters is established based on the experimental results. Experimental results indicate that it is beneficial to add certain amount O2 to modify the surface roughness of zerodur material. This finding provides an important basis for the improvement of surface roughness in APPJ of zerodur material.

  15. Simulation of the Effect of Plasma Flows in DIII-D, JET, and JT-60U

    SciTech Connect

    Porter, G D; Rognlien, T D; Rensink, M E; Loarte, A; Asakura, N; Takenaga, H; Mathews, G

    2002-05-17

    The results of 2D fluid plasma simulations of the ion flow in the boundary plasma of DIII-D, JET, and JT-60U are reported. The model includes the effects of drifts and of impurity radiation using a multi-species model of intrinsic carbon impurities. Drift effects are important in determining the primary and impurity ion fluxes in the SOL and the private region, with ExB drifts dominant. Simulated parallel velocities are consistent with experimental measurement on the high field side of JT-60U, where the parallel flow is determined by ion sources. Simulated parallel velocities are significantly less than seen in experiment at the outer midplane of JT-60U, and at the top of JET where the flow is sensitive to poloidal variations of the turbulence driven transport, suggesting the velocity in these regions is determined by transport. Parallel flows are reversed by changing the direction of the ion VB drift relative to the X-point.

  16. Streamer properties in a repetitively pulsed plasma jet from 1 to 100 kHz

    NASA Astrophysics Data System (ADS)

    Sands, Brian; Ganguly, Biswa; Scofield, James

    2015-09-01

    We investigate the properties of guided streamers in a nanosecond repetitively pulsed dielectric barrier plasma jet at repetition rates up to 100 kHz. In this regime, remnant ionization and neutral metastable concentrations are significant in the channel through which the streamer propagates. Both helium and a Penning mixture of helium and argon are investigated as feed gases for a plasma jet in a controlled pressure chamber with a flowing nitrogen background. The applied voltage pulse was set at 8 kV, with a risetime of 15 ns and falltime of 8.5 μs. Streamer dynamics were monitored using spatiotemporally-resolved emission spectroscopy with a PMT filtered at 706.5 nm He (33S - 23P) and 587.6 nm He (33D - 23P) to track the streamer head. Temporally-resolved ICCD imaging was also used to characterize discharge development. Tunable diode laser absorption spectroscopy was used to measure He (23S1) and Ar (3P2) metastable densities in the streamer channel, and streamer current was measured using an inductive current monitor. As the pulse rate is increased, the streamer dynamics are significantly altered, while production of He (23S1) and Ar (3P2) is enhanced with alternate production channels becoming important in the case of He (23S1). Work funded by Air Force Office of Scientific Research under program manager Jason Marshall.

  17. Experimental investigation on the effect of plasma jet in the triggered discharge process of a gas switch

    NASA Astrophysics Data System (ADS)

    Tie, W.; Liu, S.; Liu, X.; Zhang, Q.

    2016-08-01

    The temporal and spatial evolution of a plasma jet generated by a spark discharge was observed. The electron temperature and density were obtained under different time and gas pressures by optical emission spectroscopy. Moreover, the discharge process of the plasma-jet triggered gas switch was recorded and analyzed at the lowest working coefficient. The results showed that the plasma jet moved forward in a bullet mode, and the advancing velocity increased with the decrease of pressure, and decreased with time growing. At initial time, the maximum velocity of a plasma jet could reach 3.68 × 106 cm/s. The electron temperature decreased from 2.0 eV to 1.3 eV, and the electron density increased from 3.1 × 1015/cm3 to 6.3 × 1015/cm3 at the initial moment as the gas pressure increases from 0.1 MPa to 0.32 MPa. For a two-gap gas switch, the discharge performances were more depended on the second discharge spark gap (gap 2). Because plasma jet promoted the discharge in Gap 2, the gas switch operating in mode II had better triggered discharge characteristics. In the discharge process, the plasma-jet triggering had the effect of non-penetrating inducing, which not only provided initial electrons for reducing statistical lag but also enhanced the local electric field. The discharge was initiated and accelerated from electron avalanche to streamer. Therefore, a fast discharge was occurred in the gas switch.

  18. Coupling Of The JET ICRF Antennas In ELMy H-mode Plasmas With ITER Relevant Plasma-Straps Distance

    SciTech Connect

    Mayoral, M.-L.; Monakhov, I.; Jacquet, P.; Brix, M.; Graham, M.; Erents, K.; Korotkov, A.; Lomas, P.; Mailloux, J.; McDonald, D. C.; Stamp, M.; Walden, A.; Hobirk, J.; Ongena, J.

    2007-09-28

    In ITER, the requirement for the ICRF antenna is to deliver 20 MW in ELMy H-mode plasmas with an averaged antenna - plasma separatrix distance of 14 cm. Two major problems will have to be solved: the very fast change in antenna loading during ELMs and the decrease of the loading when the plasma is pushed far away from the antenna. JET has the capability to combine these conditions and for the first time, experiments were performed in ELMy H-mode at antenna--separatrix distance, referred as ROG, varied from 10 to 14 cm. When ROG was increased, the perturbation caused by ELMs was found to decrease significantly and the loading between ELMs was found to deteriorate to very low values. In order to compensate the latter unwanted effect, different levels of deuterium gas were injected in the edge either from the divertor, the midplane or the top of the tokamak. Using this technique, the loading was increased by up to a factor 6 and up to 8 MW of ICRF power were coupled.

  19. Characterization of Atmospheric Pressure Plasma Jet (APPJ) and Its Effect on Plasmid DNA

    NASA Astrophysics Data System (ADS)

    Adhikari, Ek; Ptasinska, Sylwia

    2015-09-01

    A helium atmospheric pressure plasma jet (APPJ) source was constructed and then characterized by monitoring a deflected current on a high voltage electrode and a potential difference between two electrodes. The deflected current was also monitored for the APPJ source with varied electrical and fed gas composition e.g. admixtures of He and water vapor. The deflected power per cycle for gas admixtures was decreased with the increase in fraction of water vapor. In addition, this APPJ source was used to induce damage to aqueous plasmid DNA. The fraction of supercoiled, single-strand breaks and double-strand breaks in DNA were quantified by using agarose gel electrophoresis. The number of DNA strand breaks increased as a function of plasma irradiation time and decrease as a distance between APPJ and DNA sample increased. The APPJ with the gas admixture, in which the fraction of water vapor was varied, was also used to induce damage to aqueous DNA samples. The damage level decreased with the increase in a fraction of water vapor under specific experimental conditions. The change in numbers of DNA strand breaks irradiated by a pure He plasma and a plasma with a gas admixture is predicted by different physical and chemical process in the APPJ. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences under Award Number DE-FC02-04ER15533.

  20. Continuum emission-based electron diagnostics for atmospheric pressure plasmas and characteristics of nanosecond-pulsed argon plasma jets

    NASA Astrophysics Data System (ADS)

    Park, Sanghoo; Choe, Wonho; Kim, Holak; Park, Joo Young

    2015-06-01

    Electron diagnostics based on electron-neutral atom (e-a) bremsstrahlung in the UV and visible range emitted from atmospheric pressure plasmas is presented. Since the spectral emissivity of the e-a bremsstrahlung is determined by electron density (ne) and mean electron temperature (Te) representing the Maxwellian electron energy distribution, their diagnostics is possible. As an example, emission spectra measured from capacitive discharges are presented, which show good agreement with the theoretically calculated emissivity of the e-a bremsstrahlung. For a single pin electrode nanosecond-pulsed plasma jet (n-PPJ) in argon, we investigate the electron properties and the temporal behavior of the positive streamers. Streamers with many branches are clearly observed inside the dielectric tube, while a few main streamers propagate outside the tube along the jet axis. A two-dimensional (2D) measurement of the time-averaged Te distribution was developed using a commercial digital camera and optical band pass filters based on the emissivity ratio of two wavelengths of the e-a bremsstrahlung. The viable measurement range of Te is 0.5-7 eV for the choice of two wavelengths of 300s and 900s nm and 0.5-4 eV for two wavelengths of 400s and 900s nm, which are uncontaminated by the atomic and/or molecular spectra. The 2D Te distribution obtained using 514.5 and 632.8 nm emissions helps to reveal the role of electrons in streamer characteristics in the argon n-PPJ. Time-averaged Te of 2.0 eV and 1.0 eV inside and outside the tube, respectively, were measured. The streamer dynamics of the n-PPJ is shown to be dependent on Te.

  1. A linear-field plasma jet for generating a brush-shaped laminar plume at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Li, Jiyuan; Chu, Jingdi; Zhang, Panpan; Jia, Pengying

    2016-06-01

    A linear-field plasma jet composed of line-to-plate electrodes is used to generate a large-scale brush-shaped plasma plume with flowing argon used as working gas. Through electrical measurement and fast photography, it is found that the plasma plume bridges the two electrodes for the discharge in the positive voltage half-cycle, which behaves like fast moving plasma bullets directed from the anode to the cathode. Compared with the positive discharge, the negative discharge only develops inside the nozzle and propagates much slower. Results also indicate that the gas temperature of the plume is close to room temperature, which is promising for biomedical application.

  2. In situ measurement of the two-dimensional temperature field of a dual-jet direct-current arc plasma.

    PubMed

    Guo, Heng; Li, Peng; Li, He-Ping; Ge, Nan; Bao, Cheng-Yu

    2016-03-01

    In this paper, a real time method for an in situ measurement of the two-dimensional (2-D) temperature filed of thermal plasmas is developed with the combination of the visible image processing technique and the spectroscopic line-ratio method at two specified wavelengths. After the calibration of the gray scale values of the recorded images with the CCD cameras by the emission intensity received using a spectrometer, the 2-D temperature field of the plasma arc-jet can be obtained conveniently based on the derived gray scale values of the CCD images at two specified wavelengths and the formula similar to that of spectroscopic line-ratio method. The experimental results show that the obtained temperature fields of the plasma arc-jet at different times are qualitatively reasonable and consistent with the modeling result. This newly developed method can be employed to measure the transient temperature fields of the plasmas with fluctuations during discharges effectively. PMID:27036772

  3. Characterization of TiO x film prepared by plasma enhanced chemical vapor deposition using a multi-jet hollow cathode plasma source

    NASA Astrophysics Data System (ADS)

    Nakamura, Masatoshi; Korzec, Dariusz; Aoki, Toru; Engemann, Jurgen; Hatanaka, Yoshinori

    2001-05-01

    The high rate deposition of TiO x film at low temperature was achieved by plasma enhanced chemical vapor deposition (PECVD) using titanium tetraisopropoxide (TTIP) as a source material. The multi-jet hollow cathode plasma source was used to generate the high-density plasma, which was showered toward the substrate. The emission spectra suggest that oxygen radicals play an important role for dissociation of the source material and for yielding the precursors. The high deposition rate up to 50 nm/min was achieved by this process. The as-deposited films are completely amorphous. They consist of structures with complex bondings including both tetrahedral and octahedral components. Though they have such complex bondings, the hydrophilicity of the PECVD film is excellent comparing to that of the annealed crystalline anatase structure. It seems that the PECVD using the multi-jet plasma source is promising for fabrication of hydrophilic TiO x films in low-temperature process.

  4. Anomalous diffusion across the magnetic field-plasma boundary - The Porcupine artificial plasma jet

    NASA Astrophysics Data System (ADS)

    Mishin, E. V.; Kapitanov, V. Ia.; Treumann, R. A.

    1986-09-01

    Very fast magnetic field diffusion into the beam is required for observation of the nearly undisturbed penetration of the Porcupine's dense, fast and heavy ion beam into the magnetized ionospheric plasma after termination of the short adiabatic phase. The diffusion is presently attributed to a transverse electron drift current-driven electrostatic instability that is excited by the diamagnetic current flowing in the boundary layer between the injected beam and the ambient field. The anomalous collision frequencies turn out to be of the order of the local lower hybrid frequency in the dense Xe plasma. Since only a very small fraction of beam energy is dissipated in the diffusion process, no significant deceleration of the ion beam is observable.

  5. Atmospheric-pressure plasma-jet from micronozzle array and its biological effects on living cells for cancer therapy

    SciTech Connect

    Kim, Kangil; Kim, Geunyoung; Yang, Sang Sik; Choi, Jae Duk; Hong, Yong Cheol; Noh, Eun Joo; Lee, Jong-Soo

    2011-02-14

    We propose a plasma-jet device with a micrometer-sized nozzle array for use in a cancer therapy. Also, we show the biological effects of atmospheric-pressure plasma on living cells. Nitrogen-plasma activated a surrogate DNA damage signal transduction pathway, called the ataxia telangiectasia mutated (ATM)-checkpoint kinase 2 pathway, suggesting that the nitrogen-plasma generates DNA double-strand breaks. Phosphorylation of H2AX and p53 was detected in the plasma-treated cells, leading to apoptotic cell death. Thus, an effect for the nitrogen plasma in the control of apoptotic cell death provides insight into the how biological effects of the nitrogen-plasma can be applied to the control of cell survival, a finding with potential therapeutic implications.

  6. Atmospheric-pressure plasma-jet from micronozzle array and its biological effects on living cells for cancer therapy

    NASA Astrophysics Data System (ADS)

    Kim, Kangil; Choi, Jae Duk; Hong, Yong Cheol; Kim, Geunyoung; Noh, Eun Joo; Lee, Jong-Soo; Yang, Sang Sik

    2011-02-01

    We propose a plasma-jet device with a micrometer-sized nozzle array for use in a cancer therapy. Also, we show the biological effects of atmospheric-pressure plasma on living cells. Nitrogen-plasma activated a surrogate DNA damage signal transduction pathway, called the ataxia telangiectasia mutated (ATM)-checkpoint kinase 2 pathway, suggesting that the nitrogen-plasma generates DNA double-strand breaks. Phosphorylation of H2AX and p53 was detected in the plasma-treated cells, leading to apoptotic cell death. Thus, an effect for the nitrogen plasma in the control of apoptotic cell death provides insight into the how biological effects of the nitrogen-plasma can be applied to the control of cell survival, a finding with potential therapeutic implications.

  7. An Alternative to Annealing TiO2 Nanotubes for Morphology Preservation: Atmospheric Pressure Plasma Jet Treatment.

    PubMed

    Seo, Sang-Hee; Uhm, Soo-Hyuk; Kwon, Jae-Sung; Choi, Eun Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2015-03-01

    Titanium oxide nanotube layer formed by plasma electrolytic oxidation (PEO) is known to be excellent in biomaterial applications. However, the annealing process which is commonly performed on the TiO2 nanotubes cause defects in the nanotubular structure. The purpose of this work was to apply a non-thermal atmospheric pressure plasma jet on diameter-controlled TiO2 nanotubes to mimic the effects of annealing while maintaining the tubular structure for use as biomaterial. Diameter-controlled nanotube samples fabricated by plasma electrolytic oxidation were dried and prepared under three different conditions: untreated, annealed at 450 °C for 1 h in air with a heating rate of 10 °C/min, and treated with an air-based non-thermal atmospheric pressure plasma jet for 5 minutes. The contact angle measurement was investigated to confirm the enhanced hydrophilicity of the TiO2 nanotubes. The chemical composition of the surface was studied using X-ray photoelectron spectroscopy, and the morphology of TiO2 nanotubes was examined by field emission scanning electron microscopy. For the viability of the cell, the attachment of the osteoblastic cell line MC3T3-E1 was determined using the water-soluble tetrazolium salt assay. We found that there are no morphological changes in the TiO2 nanotubular structure after the plasma treatment. Also, we investigated a change in the chemical composition and enhanced hydrophilicity which result in improved cell behavior. The results of this study indicated that the non-thermal atmospheric pressure plasma jet results in osteoblast functionality that is comparable to annealed samples while maintaining the tubular structure of the TiO2 nanotubes. Therefore, this study concluded that the use of a non-thermal atmospheric pressure plasma jet on nanotube surfaces may replace the annealing process following plasma electrolytic oxidation. PMID:26413696

  8. The impact of poloidal asymmetries on tungsten transport in the core of JET H-mode plasmas

    SciTech Connect

    Angioni, C.; Pütterich, T.; Bilato, R.; Casson, F. J.; Giroud, C.; Mantica, P.; Helander, P.

    2015-05-15

    Recent progress in the understanding and prediction of the tungsten behaviour in the core of JET H-mode plasmas with ITER-like wall is presented. Particular emphasis is given to the impact of poloidal asymmetries of the impurity density. In particular, it is shown that the predicted reduction of temperature screening induced by the presence of low field side localization of the tungsten density produced by the centrifugal force is consistent with the observed tungsten behaviour in a JET discharge in H-mode baseline scenario. This provides first evidence of the role of poloidal asymmetries in reducing the strength of temperature screening. The main differences between plasma parameters in JET baseline and hybrid scenario discharges which affect the impact of poloidally asymmetric density on the tungsten radial transport are identified. This allows the conditions by which tungsten accumulation can be avoided to be more precisely defined.

  9. Modelling of NO destruction in a low-pressure reactor by an Ar plasma jet: species abundances in the reactor

    NASA Astrophysics Data System (ADS)

    Kutasi, Kinga

    2011-03-01

    The destruction of NO molecules by an Ar plasma jet in a low-pressure (0.2 Torr) reactor is investigated by means of a 3D hydrodynamic model. The density distribution of species created through molecular kinetics triggered by the collision of Ar+ with NO is calculated, showing that in the case of the most abundant species a quasi-homogeneous density distribution builds up in a large part of the reactor. The conversion of NO into stable O2 and N2 molecules is followed under different plasma jet conditions and NO gas flows, and the effect of N2 addition on NO destruction is studied. It is shown that in the present system the reproduction of NO molecules on the surface through surface-assisted recombination of N and O atoms becomes impossible due to the fast disappearance of N atoms in the jet's inlet vicinity.

  10. Effects of Gas Flow Rate on the Discharge Characteristics of a DC Excited Plasma Jet

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Jia, Pengying; Di, Cong; Bao, Wenting; Zhang, Chunyan

    2015-09-01

    A direct current (DC) source excited plasma jet consisting of a hollow needle anode and a plate cathode has been developed to form a diffuse discharge plume in ambient air with flowing argon as the working gas. Using optical and electrical methods, the discharge characteristics are investigated for the diffuse plasma plume. Results indicate that the discharge has a pulse characteristic, under the excitation of a DC voltage. The discharge pulse corresponds to the propagation process of a plasma bullet travelling from the anode to the cathode. It is found that, with an increment of the gas flow rate, both the discharge plume length and the current peak value of the pulsed discharge decrease in the laminar flow mode, reach their minima at about 1.5 L/min, and then slightly increase in the turbulent mode. However, the frequency of the pulsed discharge increases in the laminar mode with increasing the argon flow rate until the argon flow rate equals to about 1.5 L/min, and then slightly decreases in the turbulent mode. supported by National Natural Science Foundation of China (Nos. 10805013, 11375051), Funds for Distinguished Young Scientists of Hebei Province, China (No. A2012201045), Department of Education for Outstanding Youth Project of China (No. Y2011120), and Youth Project of Hebei University of China (No. 2011Q14)

  11. Neutron emission from JET DT plasmas with RF heating on minority hydrogen

    NASA Astrophysics Data System (ADS)

    Henriksson, H.; Conroy, S.; Ericsson, G.; Gorini, G.; Hjalmarsson, A.; Källne, J.; Tardocchi, M.; EFDA-JET Workprogramme, contributors to the

    2002-07-01

    The neutron emission spectrum from d+t→α+n reactions has been measured as a means to study the plasma response to radio frequency (RF) power coupled to hydrogen and deuteron minority components (through fundamental and second harmonic, respectively) in a tritium discharge at JET. The spectrum was measured with the magnetic proton recoil spectrometer and was analysed in terms of two spectral components due to thermal (TH) and high-energy (HE) deuterons interacting with the bulk ion population of thermal tritons. The results were used to derive information on the deuteron population in terms of temperatures (TTH and THE) as well as corresponding particle and kinetic energy densities of the plasma; the bulk ion temperature (Ti = TTH) was determined both before (with Ohmic heating only) and during the RF pulse. Similar information on protons was derived from other measurements in order to estimate the different RF effects on protons and deuterons. This paper illustrates qualitatively the type of empirical ion kinetic information that can be obtained from neutron emission spectroscopy; the data serves as a basis for comparison with results of predictive and interpretative models on RF effects in plasmas.

  12. Comparison of atmospheric microplasma and plasma jet irradiation for increasing of skin permeability

    NASA Astrophysics Data System (ADS)

    Shimizu, K.; Tran, N. A.; Hayashida, K.; Blajan, M.

    2016-08-01

    Atmospheric plasma is attracting interest for medical applications such as sterilization, treatment of cancer cells and blood coagulation. Application of atmospheric plasma in dermatology has potential as a novel tool for wound healing, skin rejuvenation and treatment of wrinkles. In this study, we investigated the enhancement of percutaneous absorption of dye as alternative agents of transdermal drugs. Hypodermic needles are often the only way to deliver large-molecule drugs into the dermis, although a safe transdermal drug delivery method that does not require needles would be desirable. We therefore explored the feasibility of using atmospheric microplasma irradiation to enhance percutaneous absorption of drugs, as an alternative delivery method to conventional hypodermic needles. Pig skin was used as a biological sample, exposed to atmospheric microplasma, and analyzed by attenuated total reflection-Fourier transform infrared spectroscopy. A tape stripping test, a representative method for evaluating skin barrier performance, was also conducted for comparison. Transepidermal water loss (TEWL) was measured and compared with and without atmospheric microplasma irradiation, to quantify water evaporation from the inner body through the skin barrier. The results show that the stratum corneum, the outermost skin layer, could be chemically and physically modified by atmospheric microplasma irradiation. Physical damage to the skin by microplasma irradiation and an atmospheric plasma jet was also assessed by observing the skin surface. The results suggest that atmospheric microplasma has the potential to enhance percutaneous absorption.

  13. Two modes of a plasma jet excited by a direct current voltage

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Zhang, Panpan; Bao, Wenting; Jia, Pengying; Chu, Jingdi

    2016-04-01

    A plasma jet excited by a direct current voltage is developed to generate a diffuse plasma plume by blowing atmospheric pressure argon. Results show that the plume discharge operates in a single-pulsed mode or a continuous one depending on the applied voltage. For the single-pulsed mode, the discharge frequency increases with increasing the applied voltage or the air concentration, while it keeps almost constant with increasing the argon flow rate. The discharge dynamics at the breakdown stage indicate that the light emission propagates along the gas flow at a velocity in the order of 104 m s-1. The spatially resolved emission intensity at the afterglow stage of the pulsed discharge manifests a stratification into dark and bright luminous regions along the gas flow. For the continuous mode, however, the emission intensity gradually decreases along the gas flow. It is found that the continuous discharge is in a Townsend discharge regime judged from both the positive slope of the voltage-current curve and the small current density on the cathode surface. Based on optical emission spectroscopy, excited electron temperature and gas temperature of the plasma plume are obtained by a Boltzmann plot and fitting the spectra of OH radicals, respectively.

  14. Experimental Studies of Alfven Eigenmode Stability in JET D-T Plasmas

    NASA Astrophysics Data System (ADS)

    Fasoli, A.; Heeter, R.; Borba, D.; Gormezano, C.; Sharapov, S.; Jaun, A.

    1997-11-01

    Systematic studies of Alfven Eigenmodes (AE) are performed at JET, based on the excitation via resonant interaction with fast particles generated by additional heating and by fusion reactions, and via external antennas, providing a direct measurement of the mode damping rate. Similar damping rates are observed in D-D and D-T plasmas with similar configurations. In both cases the formation of an X-point provides a strong stabilising effect on low-n TAE. The fast particle drive is detected as a reduction in the measured damping rate as the fast particle pressure is increased. For ICRH power levels above the experimentally established marginal stability limit, 3 MW < P_thres < 6 MW, the magnetic fluctuation spectra indicate the destabilisation of different families of AE (TAE, EAE, kTAE, NAE). In 50:50 D-T plasmas characterised by moderate fusion power (P_fusion< 2 MW), alpha particle pressure is observed to destabilise TAE in the afterglow of the NBI and ICRH heating phase. The diagnostic potential of AE will be discussed along with the implications for the AE stability in ignited plasmas.

  15. Helium atmospheric pressure plasma jets interacting with wet cells: delivery of electric fields

    NASA Astrophysics Data System (ADS)

    Norberg, Seth A.; Johnsen, Eric; Kushner, Mark J.

    2016-05-01

    The use of atmospheric pressure plasma jets (APPJs) in plasma medicine have produced encouraging results in wound treatment, surface sterilization, deactivation of bacteria, and treatment of cancer cells. It is known that many of the reactive oxygen and nitrogen species produced by the APPJ are critical to these processes. Other key components to treatment include the ion and photon fluxes, and the electric fields produced in cells by the ionization wave of the APPJ striking in the vicinity of the cells. These relationships are often complicated by the cells being covered by a thin liquid layer—wet cells. In this paper, results from a computational investigation of the interaction of APPJs with tissue beneath a liquid layer are discussed. The emphasis of this study is the delivery of electric fields by an APPJ sustained in He/O2  =  99.8/0.2 flowing into humid air to cells lying beneath water with thickness of 200 μm. The water layer represents the biological fluid typically covering tissue during treatment. Three voltages were analyzed—two that produce a plasma effluent that touches the surface of the water layer and one that does not touch. The effect of the liquid layer thickness, 50 μm to 1 mm, was also examined. Comparisons were made of the predicted intracellular electric fields to those thresholds used in the field of bioelectronics.

  16. Synthesis of Amorphous Alloy Nanoparticles by Thermal Plasma Jet in a Quenching Tube

    NASA Astrophysics Data System (ADS)

    Choi, Sooseok; Park, Dong-Wha

    2015-09-01

    Recently, amorphous alloy nanoparticles have received a great attention in various applications such as catalysts, compact and highly efficient transformers, electrode material for Li-ion batteries, etc. Several methods such as microwave heating, laser ablation, and sonification have been studied to synthesize amorphous metal nanoparticles. In the present work, a high velocity thermal plasma jet generated by an arc plasma torch was used to produce iron alloy nanoparticles from an amorphous raw material which was a spherical shaped powder with the mean size of 25 μm. In order to synthesize amorphous alloy nanoparticles, a quenching tube where cooling gas was injected in different axial positions. Alloy nanoparticles were produced in a relatively high input power of higher than 10 kW in a fixed powder feeding at 300 mg/min. The crystallinity of synthesized nanoparticles was decreased with increasing the quenching gas flow rate. The amorphous alloy nanoparticles were found when the quenching gas injection position was 200 mm away from the exit of the plasma torch with the highest quenching gas flow rate of 20 L/min. In the numerical analysis, the highest quenching rate was also expected at the same condition.

  17. Decontamination of Chemical/Biological Warfare (CBW) Agents Using an Atmospheric Pressure Plasma Jet (APPJ)

    NASA Astrophysics Data System (ADS)

    Herrmann, Hans W.

    1998-11-01

    The atmospheric pressure plasma jet (APPJ) is a non-thermal, high pressure, uniform glow discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g. He/O_2/H_2O) which flows between an outer, grounded, cylindrical electrode and an inner, coaxial electrode powered at 13.56 MHz RF. While passing through the plasma, the feedgas becomes excited, dissociated or ionized by electron impact. Once the gas exits the discharge volume, ions and electrons are rapidly lost by recombination, but the fast-flowing effluent still contains metastables (e.g. O2*, He*) and radicals (e.g. O, OH). These reactive species have been shown to be effective neutralizers of surrogates for anthrax spores, mustard blister agent and VX nerve gas. Unlike conventional, wet decontamination methods, the plasma effluent does not cause corrosion of most surfaces and does not damage wiring, electronics, nor most plastics. This makes it highly suitable for decontamination of high value sensitive equipment such as is found in vehicle interiors (i.e. tanks, planes...) for which there is currently no good decontamination technique. Furthermore, the reactive species rapidly degrade into harmless products leaving no lingering residue or harmful byproducts. Physics of the APPJ will be discussed and results of surface decontamination experiments using simulant and actual CBW agents will be presented.

  18. Electrode Erosion in Pulsed Arc for Generating Air Meso-Plasma Jet under Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Shiki, Hajime; Motoki, Junpei; Takikawa, Hirofumi; Sakakibara, Tateki; Nishimura, Yoshimi; Hishida, Shigeji; Okawa, Takashi; Ootsuka, Takeshi

    Various materials of the rod electrode were examined in pulsed arc of PEN-Jet (Plasma ENergized-Jet) with working gas of air, which can be used for the surface treatment under atmospheric pressure. The erosion of the rod electrode was measured and it surface was observed. The amount of erosion and surface appearance were found to be different for the materials, input power and energizing time. Tungsten (W) rod electrode was oxidized immediately after starting the discharge and tungsten oxide (WO3) powder was generated over the side surface of electrode tip. This powder contaminated the treating surface. Copper (Cu) rod electrode was also oxidized immediately and CuO/Cu2O multi-layer was formed on the electrode surface. However, the erosion of Cu electrode was quite small. Platinum (Pt) and iridium (20 wt%)-contained-platinum (Pt-Ir) rod electrode were not oxidized and their erosions were significantly small. This indicated that they could be employed for keeping the constant electrode-gap and processing the surface treatment without contamination due to electrode erosion.

  19. Development of a scanning nanopipette probe microscope for fine processing using atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Morimatsu, Daisuke; Sugimoto, Hiromitsu; Nakamura, Atsushi; Ogino, Akihisa; Nagatsu, Masaaki; Iwata, Futoshi

    2016-08-01

    We developed a novel technique for fine material processing based on a localized atmospheric-pressure plasma jet (APPJ) using a scanning probe microscope equipped with a nanopipette. Using a nanopipette — a tapered glass capillary with an aperture of sub-micrometer diameter — as a nozzle makes it possible to localize the discharge area of the APPJ for fine surface processing. The nanopipette can also be used as a probe for a scanning probe microscope operated with shear-force feedback control, which is capable of positioning the pipette edge in the vicinity of material surfaces for APPJ processing and imaging of the processed surface. Sub-micrometer holes and line patterns were successfully processed on a photoresist film. It was possible to control the size of the processed patterns by varying the applied pulse voltage and the distance between the pipette and the surface.

  20. Effects of discharge voltage waveform on the discharge characteristics in a helium atmospheric plasma jet

    SciTech Connect

    Uchida, Giichiro Takenaka, Kosuke; Setsuhara, Yuichi

    2015-04-21

    We present here an analysis of the discharge characteristics of a He plasma jet operating under three different types of applied voltage waveform: (a) a μs-pulse voltage waveform with a slow voltage rise time, (b) ns-pulse, and (c) rectangular voltage waveforms with fast voltage rise time. Optical emission measurements show that the application of a voltage with a fast voltage rise time induces rapid discharge growth and, consequently, produces an abundance of energetic electrons, which in turn leads to high optical emission from the O atoms. We also estimate the optical emission efficiency of the O atom (η{sub o}), which corresponds roughly to the production efficiency of the reactive O species. η{sub o} increases with increasing applied voltage, and the highest value of η{sub o} is obtained in the shortest pulse discharge, which was ignited by a ns-pulse voltage waveform with a fast voltage rise time and short pulse width.

  1. Cell immobilization on polymer by air atmospheric pressure plasma jet treatment

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Hwan; Kwon, Jae-Sung; Om, Ji-yeon; Kim, Yong-Hee; Choi, Eun-Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2014-08-01

    The study of cell immobilization on delicate polymer by an air atmospheric pressure plasma jet (AAPPJ) is required for its medical application. The aim of this study was to evaluate whether AAPPJ treatment induce cell immobilization effect on delicate polymers without significant change of surface roughness by AAPPJ treatment. After surface roughness, dynamic contact angle, and chemical characteristics were investigated, the immobilization effect was evaluated with the mouse fibroblast L929 cell line. Surface roughness change was not observed (P > 0.05) in either delicate dental wax or polystyrene plate (PSP) as advancing and receding contact angles significantly decreased (P < 0.05), thanks to decreased hydrocarbon and formation of oxygen-related functional groups in treated PSP. Adherent L929 cells with elongated morphology were found in treated PSP along with the formation of immobilization markers vinculin and actin cytoskeleton. Increased PTK2 gene expression upregulated these markers on treated PSP.

  2. Studying tungsten under the cyclic action of a plasma gun jet

    NASA Astrophysics Data System (ADS)

    Voronin, A. V.; Gusev, V. K.; Demina, E. V.; Novokhatskii, A. N.; Prusakova, M. D.

    2014-12-01

    We have studied the cyclic action of a plasma gun jet, which modeled nonstationary thermal load related to the edge localized modes (ELMs), on the surface of tungsten elements intended for the ITER divertor. The results revealed significant changes in both the structure and morphology of a surface layer. After 100 irradiation cycles, a columnar or "ridged" structure of elements perpendicular to the initial irradiated surface is formed. Exposure to 1000 cycles changes the mechanism of material degradation and radically modifies the character of the surface topography, since the ridges are melted with the formation of droplet structures. The surface becomes rough, a loose material layer appears under the irradiated surface, and a 100-μm-thick recrystallized layer is formed.

  3. Helium/oxygen atmospheric pressure plasma jet treatment for hydrophilicity improvement of grey cotton knitted fabric

    NASA Astrophysics Data System (ADS)

    Tian, Liqiang; Nie, Huali; Chatterton, Nicholas P.; Branford-White, Christopher J.; Qiu, Yiping; Zhu, Limin

    2011-06-01

    The influence of atmospheric pressure plasma jet (APPJ) treatment on the hydrophilicity of grey cotton knitted fabric (GCKF) was investigated. For comparison, specimens which had undergone different treatments were tested by contact angle measurement, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) and X-ray diffraction (XRD). The results imply that helium/oxygen APPJ could improve the hydrophilicity of GCKF by modifying the surface properties. In addition, combining dewaxing processes with He/O 2 APPJ treatment was found to tremendously improve the hydrophilicity of GCKF. The mechanism of this was also confirmed by Ruthenium Red staining which showed most of pectic substances inside the cotton fiber existed beneath the waxy layer and on top of the cellulose microfibril.

  4. Transverse momentum diffusion and collisional jet energy loss in non-Abelian plasmas

    SciTech Connect

    Schenke, Bjoern; Strickland, Michael; Dumitru, Adrian; Nara, Yasushi; Greiner, Carsten

    2009-03-15

    We consider momentum broadening and energy loss of high-momentum partons in a hot non-Abelian plasma due to collisions. We solve the coupled system of Wong-Yang-Mills equations on a lattice in real time, including binary hard elastic collisions among the partons. The collision kernel is constructed such that the total collisional energy loss and momentum broadening are lattice-spacing independent. We find that the transport coefficient q corresponding to transverse momentum broadening receives sizable contributions from a power-law tail in the p{sub perpendicular} distribution of high-momentum partons. We establish the scaling of q and of dE/dx with density, temperature, and energy in the weak-coupling regime. We also estimate the nuclear modification factor R{sub AA} due to elastic energy loss of a jet in a classical Yang-Mills field.

  5. Linearized Boltzmann transport model for jet propagation in the quark-gluon plasma: Heavy quark evolution

    NASA Astrophysics Data System (ADS)

    Cao, Shanshan; Luo, Tan; Qin, Guang-You; Wang, Xin-Nian

    2016-07-01

    A linearized Boltzmann transport (LBT) model coupled with hydrodynamical background is established to describe the evolution of jet shower partons and medium excitations in high energy heavy-ion collisions. We extend the LBT model to include both elastic and inelastic processes for light and heavy partons in the quark-gluon plasma. A hybrid model of fragmentation and coalescence is developed for the hadronization of heavy quarks. Within this framework, we investigate how heavy flavor observables depend on various ingredients, such as different energy loss and hadronization mechanisms, the momentum and temperature dependences of the transport coefficients, and the radial flow of the expanding fireball. Our model calculations show good descriptions of the D meson suppression and elliptic flow observed at the Larege Hadron Collider and the Relativistic Heavy-Ion Collider. The prediction for the Pb-Pb collisions at √{sN N}=5.02 TeV is provided.

  6. All-vanadium redox flow batteries with graphite felt electrodes treated by atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Chen, Jian-Zhang; Liao, Wei-Yang; Hsieh, Wen-Yen; Hsu, Cheng-Che; Chen, Yong-Song

    2015-01-01

    Graphite felts modified with atmospheric pressure plasma jets (APPJs) are applied as electrodes in an all-vanadium redox flow battery (VRFB). APPJ flow penetrates deeply into the graphite felt, improving significantly the wettability of the graphite felt inside out and, thereby, enhancing graphite fiber-electrolyte contact during battery operation. The energy efficiency of a VRFB was improved from 62% (untreated) to 76% (APPJ-treated with the scan mode) at a current density of 80 mA cm-2, an improvement of 22%. The efficiency improvement is attributed to the oxygen-containing groups and nitrogen doping introduced by N2 APPJs on the fiber surfaces of graphite felt, both of which enhance electrochemical reactivity.

  7. ICRF specific plasma wall interactions in JET with the ITER-like wall

    NASA Astrophysics Data System (ADS)

    Bobkov, Vl.; Arnoux, G.; Brezinsek, S.; Coenen, J. W.; Colas, L.; Clever, M.; Czarnecka, A.; Braun, F.; Dux, R.; Huber, A.; Jacquet, P.; Klepper, C.; Lerche, E.; Maggi, C.; Marcotte, F.; Maslov, M.; Matthews, G.; Mayoral, M. L.; McCormick, K.; Meigs, A.; Milanesio, D.; Monakhov, I.; Neu, R.; Noterdaeme, J.-M.; Pütterich, Th.; Rimini, F.; Van Rooj, G.; Sergienko, G.; Van Eester, D.

    2013-07-01

    A variety of plasma wall interactions (PWIs) during operation of the so-called A2 ICRF antennas is observed in JET with the ITER-like wall. Amongst effects of the PWIs, the W content increase is the most significant, especially at low plasma densities. No increase of W source from the main divertor and entrance of the outer divertor during ICRF compared to NBI phases was found by means of spectroscopic and WI (400.9 nm) imaging diagnostics. In contrary, the W flux there is higher during NBI. Charge exchange neutrals of hydrogen isotopes could be excluded as considerable contributors to the W source. The high W content in ICRF heated limiter discharges suggests the possibility of other W sources than the divertor alone. Dependencies of PWIs to individual ICRF antennas during q95-scans, and intensification of those for the -90° phasing, indicate a link between the PWIs and the antenna near-fields. The PWIs include heat loads and Be sputtering pattern on antenna limiters. Indications of some PWIs at the outer divertor entrance are observed which do not result in higher W flux compared to the NBI phases, but are characterized by small antenna-specific (up to 25% with respect to ohmic phases) bipolar variations of WI emission. The first TOPICA calculations show a particularity of the A2 antennas compared to the ITER antenna, due to the presence of long antenna limiters in the RF image current loop and thus high near-fields across the most part of the JET outer wall.

  8. ICRF Specific Plasma Wall Interactions in JET with the ITER-Like Wall

    SciTech Connect

    Bobkov, V.; Arnoux, G.; Brezinsek, S.; Coenen, J. W.; Colas, L.; Clever, M.; Czarnecka, A.; Braun, F.; Dux, R.; Huber, Alexander; Lerche, E.; Maggi, C.; Marcotte, F.; Maslov, M.; Matthews, G.; Mayoral, M.-L.; Meigs, A. G.; Monakhov, I.; Putterich, Th.; Rimini, F.; Rooj, G. Van; Sergienko, G.; Van Eester, D.

    2013-01-01

    A variety of plasma wall interactions (PWIs) during operation of the so-called A2 ICRF antennas is observed in JET with the ITER-like wall. Amongst effects of the PWIs, the W content increase is the most significant, especially at low plasma densities. No increase of W source from the main divertor and entrance of the outer divertor during ICRF compared to NBI phases was found by means of spectroscopic and WI (400.9 nm) imaging diagnostics. In contrary, the W flux there is higher during NBI. Charge exchange neutrals of hydrogen isotopes could be excluded as considerable contributors to the W source. The high W content in ICRF heated limiter discharges suggests the possibility of other W sources than the divertor alone. Dependencies of PWIs to individual ICRF antennas during q95-scans, and intensification of those for the 90 phasing, indicate a link between the PWIs and the antenna near-fields. The PWIs include heat loads and Be sputtering pattern on antenna limiters. Indications of some PWIs at the outer divertor entrance are observed which do not result in higher W flux compared to the NBI phases, but are characterized by small antenna-specific (up to 25% with respect to ohmic phases) bipolar variations of WI emission. The first TOPICA calculations show a particularity of the A2 antennas compared to the ITER antenna, due to the presence of long antenna limiters in the RF image current loop and thus high near-fields across the most part of the JET outer wall.

  9. Laser Wakefield Structures and Electron Acceleration in Gas Jet and Capillary Discharge Plasmas

    NASA Astrophysics Data System (ADS)

    Maksimchuk, Anatoly

    2007-11-01

    Laser-driven plasma wakefield accelerators have the potential to become the next generation of particle accelerators because of the very high acceleration gradients. The beam quality from such accelerators depends critically on the details plasma wave spatial structures. In experiments at the University of Michigan it was possible in a single shot by frequency domain holography (FDH) to visualize individual plasma waves produced by the 40 TW, 30 fs Hercules laser focused to the intensity of 10^19 W/cm^2 onto a supersonic He gas jet [1]. These holographic ``snapshots'' capture the evolution of multiple wake periods, and resolve wavefront curvature seen previously only in simulations. High-energy quasi-monoenergetic electron beams for plasma density in the specific range 1.5x10^19<=ne<=3.5x10^19 cm-3 were generated [2]. The experiments show that the energy, charge, divergence and pointing stability of the beam can be controlled by changing ne, and that higher electron energies and more stable beams are produced for lower densities. An optimized quasi-monoenergetic beam of over 300 MeV and 10 mrad angular divergence is demonstrated at a plasma density of ne=1.5x10^19 cm-3. The resulted relativistic electron beams have been used to perform gamma-neutron activation of ^12C and ^63Cu and photo-fission of ^238U with a record high reaction yields of ˜5x10^5/Joule [3]. Experiments performed with ablative capillary discharge plasma demonstrate stable guiding for laser power up to 10 TW with the transmission of 50% and guided intensity of ˜10^17 W/cm^2. Study of the staged electron acceleration have been performed which uses ablated plasma in front of the capillary to inject electrons into the wakefield structures. [1] N. H. Matlis et. al., Nature Physics 2, 749 (2006). [2] A. Maksimchuk et. al., Journal de Physique IV 133, 1123 (2006). [3] S. A. Reed et. al., Appl. Phys. Lett. 89, 231107 (2006).

  10. Characterization of Plasma Jet in Plasma Spray-Physical Vapor Deposition of YSZ Using a <80 kW Shrouded Torch Based on Optical Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Qing-Yu; Peng, Xiao-Zhuang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2015-08-01

    During plasma spray-physical vapor deposition (PS-PVD) of yttria-stabilized zirconia (YSZ) coatings, evaporation of the YSZ powder is essential, but quite difficult when using a commercial <80 kW plasma torch. In this study, a shrouded plasma torch was examined to improve the YSZ evaporation. The plasma characteristics were diagnosed using optical emission spectroscopy. Results showed that the electron number density in the plasma jet was maintained at an order of magnitude of 1014 cm-3, indicating local thermal equilibrium of the plasma jet. Compared with a conventional torch, the shrouded torch resulted in much higher plasma temperature and much lower electron number density. With the shrouded torch, more energy of the plasma was transferred to the YSZ material, leading to more evaporation of the YSZ powder and thereby a much higher deposition rate of the YSZ coating. These results show that use of a shrouded torch is a simple and effective approach to improve the evaporation of feedstock material during PS-PVD.

  11. Coherent structures in plasma-actuator controlled supersonic jets: Axisymmetric and mixed azimuthal modes

    NASA Astrophysics Data System (ADS)

    Gaitonde, D. V.; Samimy, M.

    2011-09-01

    High-fidelity simulations are employed to study the effect of eight localized arc filament plasma actuators placed around the periphery of a Mach 1.3 converging-diverging nozzle exit. Emphasis is placed on understanding the coherent structures generated by axisymmetric (m = 0), flapping or first mixed (m = ±1) and second mixed (m = ±2) modes, which are excited at the jet column-mode frequency corresponding to a Strouhal number based on jet diameter of 0.3. Baseline (no control) and constant excitation (actuators on continuously) cases are also simulated. Comparisons with experimental results indicate that the computational model reproduces the main features induced by the actuators. Furthermore, the mean flow exhibits many similarities with the theoretical predictions of Cohen and Wygnanski [J. Fluid Mech. 176, 221 (1987)]. Overall, the results indicate a complex coherent structure generation, evolution, and disintegration process. For m = ±1, the phase-averaged flow reveals successive distorted elliptic vortex rings with axes in the flapping plane but alternating on either side of the jet axis. This generates a chain of structures each of which interacts with its predecessor on one side of the major plane and its successor on the other. Through self and mutual induction, the leading segment of each loop is pinched and passes through the previous ring before rapidly breaking up. The m = ±2 mode yields elliptic structures with major axes of successive rings being aligned with the two symmetry planes, which are orthogonal to each other. The minor axis side is pulled downstream faster than the rest of the structure because of the higher velocity near the jet centerline and self-induced effects, yielding a horse-shoe shape when viewed in profile. The m = 0 mode exhibits axisymmetric roll-up events, with vortex ribs in the braid regions connecting successive large coherent structures. The constant excitation (with largest energy input) and baseline cases are similar

  12. Decomposition of Methylene Blue by using an Atmospheric Plasma Jet with Ar, N2, O2, or Air

    NASA Astrophysics Data System (ADS)

    Takemura, Yuichiro; Yamaguchi, Naohiro; Hara, Tamio

    2013-05-01

    We have performed experiments on the decomposition of methylene blue by using an atmospheric plasma jet with various working gases. The decomposition efficiencies of Ar, N2, and O2 plasmas are almost equivalent; on the other hand, the rate of methylene blue decomposition by air plasma is lower than those by the other plasmas. From the absorption spectra, it has been found that HONO (nitrous acid) is produced by air plasma-liquid reactions. It has been clarified by a series of experiments, where oxygen concentration in N2 plasma is varied, that the concentration of HONO increases and the rate of methylene blue decomposition degrades with increasing oxygen gas flow rate. Furthermore, the presence of nitrate ions and nitrite ions was confirmed by ion chromatography and pH measurement.

  13. Influence of He/O 2 atmospheric pressure plasma jet treatment on subsequent wet desizing of polyacrylate on PET fabrics

    NASA Astrophysics Data System (ADS)

    Li, Xuming; Lin, Jun; Qiu, Yiping

    2012-01-01

    The influence of He/O2 atmospheric pressure plasma jet (APPJ) treatment on subsequent wet desizing of polyacrylate on PET fabrics was studied in the present paper. Weight loss results indicated that the weight loss increased with an increase of plasma treatment time. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed an increased surface roughness after the plasma treatment. SEM also showed that the fiber surfaces were as clean as unsized fibers after 35 s treatment followed by NaHCO3 desizing. X-ray photoelectron spectroscopy (XPS) analysis indicated that oxygen-based functional groups increased for the plasma treated polyacrylate sized fabrics. The percent desizing ratio (PDR) results showed that more than 99% PDR was achieved after 65 s plasma treatment followed by a 5 min NaHCO3 desizing. Compared to conventional wet desizing, indicating that plasma treatment could significantly reduce desizing time.

  14. Enhancing The Mode Conversion Efficiency In JET Plasmas With Multiple Mode Conversion Layers

    SciTech Connect

    Van Eester, D.; Lerche, E.; Ongena, J.; Mayoral, M.-L.; Beaumont, P.; Blackman, T.; Brennan, D.; Brett, A.; Coffey, I.; Coyne, A.; Felton, R.; Giroud, C.; Jacquet, P.; Kiptily, V.; Knipe, S.; Monakhov, I.; Noble, C.; Pangioni, L.

    2011-12-23

    The constructive interference effect described by Fuchs et al. [1] shows that the mode conversion and thereby the overall heating efficiency can be enhanced significantly when an integer number of fast wave wavelengths can be folded in between the high field side fast wave cutoff and the ion-ion hybrid layer(s) at which the ion Bernstein or ion cyclotron waves are excited. This effect was already experimentally identified in ({sup 3}He)-D plasmas [2] and was recently tested in ({sup 3}He)-H JET plasmas. The latter is an 'inverted' scenario, which differs significantly from the ({sup 3}He)-D scenarios since the mode-conversion layer is positioned between the low field side edge of the plasma and the ion-cyclotron layer of the minority {sup 3}He ions (whereas the order in which a wave entering the plasma from the low field side encounters these layers is inverted in a 'regular' scenario), and because much lower {sup 3}He concentrations are needed to achieve the mode-conversion heating regime. The presence of small amounts of {sup 4}He and D in the discharges gave rise to an additional mode conversion layer on top of the expected one associated with {sup 3}He-H, which made the interpretation of the results more complex but also more interesting: Three different regimes could be distinguished as a function of X[{sup 3}He], and the differing dynamics at the various concentrations could be traced back to the presence of these two mode conversion layers and their associated fast wave cutoffs. Whereas (1-D and 2-D) numerical modeling yields quantitative information on the RF absorptivity, recent analytical work by Kazakov [3] permits to grasp the dominant underlying wave interaction physics.

  15. Dual effects of atmospheric pressure plasma jet on skin wound healing of mice.

    PubMed

    Xu, Gui-Min; Shi, Xing-Min; Cai, Jing-Fen; Chen, Si-Le; Li, Ping; Yao, Cong-Wei; Chang, Zheng-Shi; Zhang, Guan-Jun

    2015-01-01

    Cold plasma has become an attractive tool for promoting wound healing and treating skin diseases. This article presents an atmospheric pressure plasma jet (APPJ) generated in argon gas through dielectric barrier discharge, which was applied to superficial skin wounds in BALB/c mice. The mice (n = 50) were assigned randomly into five groups (named A, B, C, D, E) with 10 animals in each group. Natural wound healing was compared with stimulated wound healing treated daily with APPJ for different time spans (10, 20, 30, 40, and 50 seconds) on 14 consecutive days. APPJ emission spectra, morphological changes in animal wounds, and tissue histological parameters were analyzed. Statistical results revealed that wound size changed over the duration of the experimental period and there was a significant interaction between experimental day and group. Differences between group C and other groups at day 7 were statistically significant (p < 0.05). All groups had nearly achieved closure of the untreated control wounds at day 14. The wounds treated with APPJ for 10, 20, 30, and 40 seconds showed significantly enhanced daily improvement compared with the control and almost complete closure at day 12, 10, 7, and 13, respectively. The optimal results of epidermal cell regeneration, granulation tissue hyperplasia, and collagen deposition in histological aspect were observed at day 7. However, the wounds treated for 50 seconds were less well healed at day 14 than those of the control. It was concluded that appropriate doses of cold plasma could inactivate bacteria around the wound, activate fibroblast proliferation in wound tissue, and eventually promote wound healing. Whereas, over doses of plasma suppressed wound healing due to causing cell death by apoptosis or necrosis. Both positive and negative effects may be related to the existence of reactive oxygen and nitrogen species (ROS and RNS) in APPJ. PMID:26342154

  16. Atmospheric pressure plasma jet utilizing Ar and Ar/H2O mixtures and its applications to bacteria inactivation

    NASA Astrophysics Data System (ADS)

    Cheng, Cheng; Shen, Jie; Xiao, De-Zhi; Xie, Hong-Bing; Lan, Yan; Fang, Shi-Dong; Meng, Yue-Dong; Chu, Paul K.

    2014-07-01

    An atmospheric pressure plasma jet generated with Ar with H2O vapor is characterized and applied to inactivation of Bacillus subtilis spores. The emission spectra obtained from Ar/H2O plasma shows a higher intensity of OH radicals compared to pure argon at a specified H2O concentration. The gas temperature is estimated by comparing the simulated spectra of the OH band with experimental spectra. The excitation electron temperature is determined from the Boltzmann's plots and Stark broadening of the hydrogen Balmer Hβ line is applied to measure the electron density. The gas temperature, excitation electron temperature, and electron density of the plasma jet decrease with the increase of water vapor concentration at a fixed input voltage. The bacteria inactivation rate increases with the increase of OH generation reaching a maximum reduction at 2.6% (v/v) water vapor. Our results also show that the OH radicals generated by the Ar/H2O plasma jet only makes a limited contribution to spore inactivation and the shape change of the spores before and after plasma irradiation is discussed.

  17. Two-photon absorption laser induced fluorescence measurement of atomic oxygen density in an atmospheric pressure air plasma jet

    NASA Astrophysics Data System (ADS)

    Conway, J.; Gogna, G. S.; Gaman, C.; Turner, M. M.; Daniels, S.

    2016-08-01

    Atomic oxygen number density [O] is measured in an air atmospheric pressure plasma jet (APPJ) using two-photon absorption laser induced fluorescence (TALIF). Gas flow is fixed at 8 slpm, the RF power coupled into the plasma jet varied between 5 W and 20 W, and the resulting changes in atomic oxygen density measured. Photolysis of molecular oxygen is employed to allow in situ calibration of the TALIF system. During calibration, O2 photo-dissociation and two-photon excitation of the resulting oxygen atoms are achieved within the same laser pulse. The atomic oxygen density produced by photolysis is time varying and spatially non-uniform which needs to be corrected for to calibrate the TALIF system for measurement of atomic oxygen density in plasma. Knowledge of the laser pulse intensity I 0(t), wavelength, and focal spot size allows correction factors to be determined using a rate equation model. Atomic oxygen is used for calibration and measurement, so the laser intensity can be increased outside the TALIF quadratic laser power dependence region without affecting the calibration reliability as the laser power dependence will still be the same for both. The atomic O density results obtained are not directly benchmarked against other known density measurement techniques. The results show that the plasma jet atomic oxygen content increases as the RF power coupled into the plasma increases.

  18. Double layers and plasma-wave resistivity in extragalactic jets - Cavity formation and radio-wave emission

    NASA Technical Reports Server (NTRS)

    Borovsky, Joseph E.

    1987-01-01

    Current driven electrostatic-wave- and electromagnetic-wave-produced resistivities do not occur in extragalactic jets for estimated values of the carried currents. Strong plasma double layers, however, may exist within self-maintained density cavities. The relativistic double-layer-emitted electron and ion beams drive plasma-wave resistivities in the low- and high-potential plasma adjacent to the double layers. The double-layer-emitted electron beams may also emit polarized radio waves via a collective bremsstrahlung process mediated by electrostatic two-stream instabilities.

  19. Double layers and plasma-wave resistivity in extragalactic jets: Cavity formation and radio-wave emission

    NASA Technical Reports Server (NTRS)

    Borovsky, Joseph E.

    1987-01-01

    For estimated values of the currents carried by extragalactic jets, current-driven electrostatic-wave- and electromagnetic-wave-produced resistivities do not occur. Strong plasma double layers, however, may exist within self-maintained density cavities, the relativistic double-layer-emitted electron, and ion beams driving plasma-wave resistivities in the low- and high-potential plasma adjacent to the double layers. The double-layer-emitted electron beams may also emit polarized radio waves via a collective bremsstrahlung process mediated by electrostatic two-stream instabilities.

  20. Plasma effects on the generation of reactive oxygen and nitrogen species in cancer cells in-vitro exposed by atmospheric pressure pulsed plasma jets

    NASA Astrophysics Data System (ADS)

    Kim, Sun Ja; Chung, T. H.

    2015-08-01

    Atmospheric pressure pulsed helium plasma jets are utilized for plasma-cell interactions. The effect of operating parameters such as applied voltage, pulse repetition frequency, and duty ratio on the generation of specific reactive oxygen and nitrogen species in gas and liquid phases and within cells is investigated. The apoptotic changes detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling assay in cells caused by plasma exposure are observed to correlate well with the levels of extracellular and intracellular reactive oxygen and nitrogen species.

  1. Multi-Spacecraft Analysis of Plasma Jet Events and Associated Whistler-Wave Emissions using MMS Data

    NASA Astrophysics Data System (ADS)

    Breuillard, Hugo; Le Contel, Olivier; Retino, Alessandro; Chasapis, Alexandros; Chust, Thomas; Cohen, Ian; Wilder, Frederick; Graham, Daniel; Khotyaintsev, Yuri

    2016-04-01

    Plasma jets aka bursty bulk flows play a crucial role in Earth's plasmasheet dynamics, in particular during substorms where they can sometimes even penetrate down to the geosynchronous orbit. The energy input from the solar wind is partly dissipated in jet fronts(also called dipolarization fronts) in the form of strong whistler waves that can heat and accelerate energetic electrons. The ratio of the energy transported during jets to the substorm energy consumption is still under debate due to instrumental limitations. In May 2015 the Magnetospheric Multiscale (MMS) mission evolves in a string-of-pearls configuration with an average inter-satellite distance of 300 km which allows us to study in detail the microphysics of these phenomena. Thus in this study we employ MMS data to investigate the properties of jet fronts propagating earthward and their associated whistler-mode wave emissions. We show that the spatial dynamics of jet fronts are of the order of the ion gyroradius and whistler-wave dynamics have a temporal scale of a few seconds. We also investigate the energy dissipation associated with such waves and their interaction with energetic electrons in the vicinity of the flow/jet braking region. In addition, we make use of ray tracing simulations to evaluate their propagation properties, as well as their impact on particles in the off-equatorial magnetosphere.

  2. Characterization of diamond-like carbon thin film synthesized by RF atmospheric pressure plasma Ar/CH4 jet

    NASA Astrophysics Data System (ADS)

    Sohbatzadeh, Farshad; Safari, Reza; Etaati, G. Reza; Asadi, Eskandar; Mirzanejhad, Saeed; Hosseinnejad, Mohammad Taghi; Samadi, Omid; Bagheri, Hanieh

    2016-01-01

    The growth of diamond like carbon (DLC) on a Pyrex glass was investigated by a radio frequency (RF) atmospheric pressure plasma jet (APPJ). The plasma jet with capacitive configuration ran by a radio frequency power supply at 13.56 MHz. Alumina ceramic was used as dielectric barrier. Ar and CH4 were used in atmospheric pressure as carrier and precursor gases, respectively. Diamond like carbon thin films were deposited on Pyrex glass at substrate temperature and applied power of 130 °C and 250 Watts, respectively. Performing field emission scanning electron microscope (FE-SEM) and laser Raman spectroscopy analysis resulted in deposition rate and the ID/IG ratio of 21.31 nm/min and 0.47, respectively. The ID/IG ratio indicated that the coating possesses relative high sp3 content The optical emission spectroscopy (OES) diagnostic was applied to diagnose plasma jet species. Estimating electron temperature and density of the RF-APPJ resulted in 1.36 eV and 2.75 × 1014 cm-3 at the jet exit, respectively.

  3. A model study of the plasma chemistry of stratospheric Blue Jets

    NASA Astrophysics Data System (ADS)

    Winkler, Holger; Notholt, Justus

    2015-04-01

    Stratospheric Blue Jets (BJs) are upward propagating discharges in the altitude range 15-40 km above thunderstorms. They appear as conical bodies of blue light originating at the top of thunderclouds and proceed upward with velocities of the order of 100 km/s. Electric discharges in the atmosphere are known to have chemical effects. Of particular interest is the liberation of atomic oxygen and the formation of reactive nitrogen radicals. We have used a numerical plasma chemistry model in order to simulate the chemical processes in stratospheric BJs. It was applied to BJ streamers in the altitude range 18-38 km. The model results show that there is a production of ozone from atomic oxygen liberated at the streamer tips. At the same time, significant amounts of nitric oxide are produced. Compared to earlier plasma chemistry simulations of BJ streamers, the production of NO and O3 is by orders of magnitude larger. Additionally, the chemical processes in the leader part of a BJ have been simulated for the first time. In the leader channel, driven by high-temperature reactions, the concentration of N2O and NO increases by several orders of magnitude, and there is a significant depletion of ozone. The model results might gain importance by the fact that the chemical perturbations in BJs are largest at altitudes of the stratospheric ozone layer.

  4. SnO2/CNT nanocomposite supercapacitors fabricated using scanning atmospheric-pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Xu, Chang-Han; Chiu, Yi-Fan; Yeh, Po-Wei; Chen, Jian-Zhang

    2016-08-01

    SnO2/CNT electrodes for supercapacitors are fabricated by first screen-printing pastes containing SnO2 nanoparticles and CNTs on carbon cloth, following which nitrogen atmospheric pressure plasma jet (APPJ) sintering is performed at various APPJ scan rates. The APPJ scan rates change the time intervals for which the reactive plasma species and the heat of the nitrogen APPJs influence the designated sintering spot on the carbon cloth, resulting in APPJ-sintered SnO2/CNT nanocomposites with different properties. The water contact angle decreases with the APPJ scan rate. The improved wettability can facilitate the penetration of the electrolyte into the nanopores of the SnO2/CNT nanocomposites, thereby improving the charge storage and specific capacitance of the supercapacitors. Among the three tested APPJ scan rates, 1.5, 3, and 6 mm s‑1, the SnO2/CNT supercapacitor sintered by APPJ under the lowest APPJ scan rate of 1.5 mm s‑1 shows the best specific capacitance of ∼90 F g‑1 as evaluated by cyclic voltammetry under a potential scan rate of 2 mV s‑1. A high APPJ scan rate may result in low degree of materials activation and sintering, leading to poorer performance of SnO2/CNT supercapacitors. The results suggest the feasibility of an APPJ roll-to-roll process for the fabrication of SnO2/CNT nanocomposite supercapacitors.

  5. Maximizing power dissipation by impurity seeding on JET with metal plasma facing components

    NASA Astrophysics Data System (ADS)

    Wischmeier, Marco; Huber, Alexander; Lowry, Christopher; Maggi, Costanza; Reinke, Matthew; JET contributors Team

    2015-11-01

    A reactor such as DEMO will operate at considerably higher total heating power even when compared to ITER. This will require mitigating a much higher power flux density in the Scrape-Off Layer. A highly detached divertor will be required for maximizing the lifetime of the eroding plasma facing components, PFCs, in the divertor as well as for operating within the engineering limits expected for the power handling components. A dissipation of ~ 95% of the total heating power will be needed, with more than 70% being radiation on closed field lines. On JET with metal PFCs highly radiative conditions with N2, Ne, both combined and Ar as radiators were approached in H-mode plasmas. For all seeding species radiative power fractions larger than 70% were achieved under stable discharge conditions with a concentration of the radiation in the X-point region. Detachment along both divertor plates was complete. A degradation of the pedestal profile was compensated by steeper core profiles. See the Appendix of F. Romanelli et al., 25th FEC 2014, Russia, Supported by EUROfusion No 633053.

  6. Non-Thermal Equilibrium Atmospheric Pressure Glow-Like Discharge Plasma Jet

    NASA Astrophysics Data System (ADS)

    Chang, Zhengshi; Yao, Congwei; Zhang, Guanjun

    2016-01-01

    Non-thermal equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises various innovative applications, and the uniform APPJ is more favored. Glow discharge is one of the most effective methods to obtain the uniform discharge. Compared with the glow dielectric barrier discharge (DBD) in atmospheric pressure, pure helium APPJ shows partial characteristics of both the glow discharge and the streamer. In this paper, considering the influence of the Penning effect, the electrical and optical properties of He APPJ and Ar/NH3 APPJ were researched. A word “Glow-like APPJ” is used to characterize the uniformity of APPJ, and it was obtained that the basic characteristics of the glow-like APPJ are driven by the kHz AC high voltage. The results can provide a support for generating uniform APPJ, and lay a foundation for its applications. supported by National Natural Science Foundation of China (Nos. 51307133, 51125029, 51221005) and the Fundamental Research Funds for the Central Universities of China (Nos. xjj2012132, xkjc2013004)

  7. Discharge processes and an electrical model of atmospheric pressure plasma jets in argon

    NASA Astrophysics Data System (ADS)

    Fang, Zhi; Shao, Tao; Yang, Jing; Zhang, Cheng

    2016-01-01

    In this paper, an atmospheric pressure plasma discharge in argon was generated using a needle-to-ring electrode configuration driven by a sinusoidal excitation voltage. The electric discharge processes and discharge characteristics were investigated by inspecting the voltage-current waveforms, Lissajous curves and lighting emission images. The change in discharge mode with applied voltage amplitude was studied and characterised, and three modes of corona discharge, dielectric barrier discharge (DBD) and jet discharge were identified, which appeared in turn with increasing applied voltage and can be distinguished clearly from the measured voltage-current waveforms, light-emission images and the changing gradient of discharge power with applied voltage. Based on the experimental results and discharge mechanism analysis, an equivalent electrical model and the corresponding equivalent circuit for characterising the whole discharge processes accurately was proposed, and the three discharge stages were characterised separately. A voltage-controlled current source (VCCS) associated with a resistance and a capacitance were used to represent the DBD stage, and the plasma plume and corona discharge were modelled by a variable capacitor in series with a variable resistor. Other factors that can influence the discharge, such as lead and stray capacitance values of the circuit, were also considered in the proposed model. Contribution to the Topical Issue "Recent Breakthroughs in Microplasma Science and Technology", edited by Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu.

  8. Syngas production from tar reforming by microwave plasma jet at atmospheric pressure: power supplied influence

    NASA Astrophysics Data System (ADS)

    de Souza Medeiros, Henrique; Justiniano, Lucas S.; Gomes, Marcelo P.; Soares da Silva Sobrinho, Argemiro; Petraconi Filho, Gilberto

    2013-09-01

    Now a day, scientific community is searching for new fuels able to replace fossil fuels with economic and environment gains and biofuel play a relevant rule, mainly for the transport sector. A major process to obtaining such type of renewable resource is biomass gasification. This process has as product a gas mixture containing CO, CH4, and H2 which is named synthesis gas (syngas). However, an undesirable high molecular organic species denominated tar are also produced in this process which must be removed. In this work, results of syngas production via tar reforming in the atmospheric pressure microwave discharge having as parameter the power supply. Argon, (argon + ethanol), and (argon + tar solution) plasma jet were produced by different values of power supplied (from 0.5 KW to 1.5 KW). The plasma compounds were investigated by optical spectroscopy to each power and gas composition. The main species observed in the spectrum are Ar, CN, OII, OIV, OH, H2, H(beta), CO2, CO, and SIII. This last one came from tar. The best value of the power applied to syngas production from tar reforming was verified between 1.0 KW and 1.2 KW. We thank the following institutions for financial support: CNPq, CAPES, and FAPESP.

  9. Study of thermal and electrical parameters of workpieces during spray coating by electrolytic plasma jet

    NASA Astrophysics Data System (ADS)

    Khafizov, A. A.; Shakirov, Yu I.; Valiev, R. A.; Valiev, R. I.; Khafizova, G. M.

    2016-01-01

    In this paper the results are presented of thermal and electrical parameters of products in the system bottom layer - intermediate layer when applying protective coatings of ferromagnetic powder by plasma spray produced in an electric discharge with a liquid cathode, on steel samples. Temperature distribution and gradients in coating and intermediate coating were examined. Detailed descriptions of spray coating with ferromagnetic powder by plasma jet obtained in electrical discharge with liquid cathode and the apparatus for obtaining thereof is provided. Problem has been solved by using of Fourier analysis. Initial data for calculations is provided. Results of numerical analysis are provided as temporal functions of temperature in contiguity between coating and intermediate coating as well as temporal function of the value Q=q-φ where q is density of heat current directed to the free surface of intermediate coating, φ is density of heat current in contiguity between coating and intermediate coating. The analysis of data given shows that in the systems of contact heat exchange bottom layer-intermediate layer with close values of the thermophysical characteristics of constituting materials is observed a slow increase of the temperature of the contact as a function of time.

  10. Effects of irradiation distance on supply of reactive oxygen species to the bottom of a Petri dish filled with liquid by an atmospheric O2/He plasma jet

    NASA Astrophysics Data System (ADS)

    Kawasaki, Toshiyuki; Kusumegi, Shota; Kudo, Akihiro; Sakanoshita, Tomohiro; Tsurumaru, Takuya; Sato, Akihiro; Uchida, Giichiro; Koga, Kazunori; Shiratani, Masaharu

    2016-05-01

    The impact of irradiation distances on plasma jet-induced specific effects on the supply of reactive oxygen species (ROS) to the bottom of a Petri dish filled with liquid was investigated using a KI-starch gel reagent that can be employed as a ROS indicator even in water. O3 exposure experiments without plasma irradiation were also performed to elucidate the specific effects of the plasma jet. Relative concentrations of ROS transported to the bottom were evaluated using absorbance measurements. The results indicated that ROS supply to the bottom is markedly enhanced by the plasma jet irradiation at shorter irradiation distances, whereas similar results could not be obtained for the O3 exposure. In these cases, the liquid mixing in the depth direction was also enhanced by the plasma jet irradiation only, and the supply of reactive atomic oxygen to the liquid surface was markedly increased as well.

  11. Using a magnetized plasma jet colliding with a heavy gas cloud to investigate MIF adiabatic heating and compression mechanisms

    NASA Astrophysics Data System (ADS)

    Bellan, Paul; Wongwaitayakornkul, Pakorn; Chai, Kil-Byoung; Greig, Amelia; Li, Hui

    2015-11-01

    Magnetized inertial fusion (MIF) is based on having an imploding liner adiabatically compress a magnetized plasma to the density and temperature required for thermonuclear fusion. The goal of the Caltech research program is to determine the scaling of the temperature and density increase when an actual experimental plasma is adiabatically compressed. The plasma parameters will be more modest than a fusion-grade configuration, but in compensation, the shot repetition rate will be much higher and the experiments will be non-destructive. The non-destructive feature results from having a high-speed magnetized plasma jet impact a localized heavy gas. From the point of view of an observer in the frame of the magnetized plasma jet, it will look as if the heavy gas is impacting and compressing the magnetized plasma and so, except for some geometrical differences, the configuration is equivalent to a liner impacting and compressing a stationary magnetized plasma. The experiment will be modeled by 3D numerical MHD and PIC codes. (as of approximately September 15).

  12. Cold atmospheric pressure plasma jets: Interaction with plasmid DNA and tailored electron heating using dual-frequency excitation

    NASA Astrophysics Data System (ADS)

    Niemi, K.; O'Neill, C.; Cox, L. J.; Waskoenig, J.; Hyland, W. B.; McMahon, S. J.; Reuter, S.; Currell, F. J.; Graham, W. G.; O'Connell, D.; Gans, T.

    2012-05-01

    Recent progress in plasma science and technology has enabled the development of a new generation of stable cold non-equilibrium plasmas operating at ambient atmospheric pressure. This opens horizons for new plasma technologies, in particular in the emerging field of plasma medicine. These non-equilibrium plasmas are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. The effect of a cold radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks. Plasma manipulation techniques for controlled energy delivery are highly desirable. Numerical simulations are employed for detailed investigations of the electron dynamics, which determines the generation of reactive species. New concepts based on nonlinear power dissipation promise superior strategies to control energy transport for tailored technological exploitations.

  13. Cold atmospheric pressure plasma jets: Interaction with plasmid DNA and tailored electron heating using dual-frequency excitation

    SciTech Connect

    Niemi, K.; O'Neill, C.; Cox, L. J.; Waskoenig, J.; Hyland, W. B.; McMahon, S. J.; Reuter, S.; Currell, F. J.; Graham, W. G.; O'Connell, D.; Gans, T.

    2012-05-25

    Recent progress in plasma science and technology has enabled the development of a new generation of stable cold non-equilibrium plasmas operating at ambient atmospheric pressure. This opens horizons for new plasma technologies, in particular in the emerging field of plasma medicine. These non-equilibrium plasmas are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. The effect of a cold radio frequency-driven atmospheric pressure plasma jet on plasmid DNA has been investigated. The formation of double strand breaks correlates well with the atomic oxygen density. Taken with other measurements, this indicates that neutral components in the jet are effective in inducing double strand breaks. Plasma manipulation techniques for controlled energy delivery are highly desirable. Numerical simulations are employed for detailed investigations of the electron dynamics, which determines the generation of reactive species. New concepts based on nonlinear power dissipation promise superior strategies to control energy transport for tailored technological exploitations.

  14. Atmospheric-pressure plasma jets: Effect of gas flow, active species, and snake-like bullet propagation

    SciTech Connect

    Wu, S.; Wang, Z.; Huang, Q.; Tan, X.; Lu, X.; Ostrikov, K.

    2013-02-15

    Cold atmospheric-pressure plasma jets have recently attracted enormous interest owing to numerous applications in plasma biology, health care, medicine, and nanotechnology. A dedicated study of the interaction between the upstream and downstream plasma plumes revealed that the active species (electrons, ions, excited OH, metastable Ar, and nitrogen-related species) generated by the upstream plasma plume enhance the propagation of the downstream plasma plume. At gas flows exceeding 2 l/min, the downstream plasma plume is longer than the upstream plasma plume. Detailed plasma diagnostics and discharge species analysis suggest that this effect is due to the electrons and ions that are generated by the upstream plasma and flow into the downstream plume. This in turn leads to the relatively higher electron density in the downstream plasma. Moreover, high-speed photography reveals a highly unusual behavior of the plasma bullets, which propagate in snake-like motions, very differently from the previous reports. This behavior is related to the hydrodynamic instability of the gas flow, which results in non-uniform distributions of long-lifetime active species in the discharge tube and of surface charges on the inner surface of the tube.

  15. Membrane damage and active but nonculturable state in liquid cultures of Escherichia coli treated with an atmospheric pressure plasma jet.

    PubMed

    Dolezalova, Eva; Lukes, Petr

    2015-06-01

    Electrical discharge plasmas can efficiently inactivate various microorganisms. Inactivation mechanisms caused by plasma, however, are not fully understood because of the complexity of both the plasma and biological systems. We investigated plasma-induced inactivation of Escherichia coli in water and mechanisms by which plasma affects bacterial cell membrane integrity. Atmospheric pressure argon plasma jet generated at ambient air in direct contact with bacterial suspension was used as a plasma source. We determined significantly lower counts of E. coli after treatment by plasma when they were assayed using a conventional cultivation technique than using a fluorescence-based LIVE/DEAD staining method, which indicated that bacteria may have entered the viable-but-nonculturable state (VBNC). We did not achieve resuscitation of these non-culturable cells, however, we detected their metabolic activity through the analysis of cellular mRNA, which suggests that cells may have been rather in the active-but-nonculturable state (ABNC). We hypothesize that peroxidation of cell membrane lipids by the reactive species produced by plasma was an important pathway of bacterial inactivation. Amount of malondialdehyde and membrane permeability of E. coli to propidium iodide increased with increasing bacterial inactivation by plasma. Membrane damage was also demonstrated by detection of free DNA in plasma-treated water. PMID:25212700

  16. Experimental characterization of a transition from collisionless to collisional interaction between head-on-merging supersonic plasma jetsa)

    SciTech Connect

    Moser, Auna L.; Hsu, Scott C.

    2015-05-01

    We present results from experiments on the head-on merging of two supersonic plasma jets in an initially collisionless regime for the counter-streaming ions [A. L. Moser & S. C. Hsu, Phys. Plasmas, submitted (2014)]. The plasma jets are of either an argon/impurity or hydrogen/impurity mixture and are produced by pulsed-power-driven railguns. Based on time- and space-resolved fast-imaging, multi-chord interferometry, and survey-spectroscopy measurements of the overlapping region between the merging jets, we observe that the jets initially interpenetrate, consistent with calculated inter-jet ion collision lengths, which are long. As the jets interpenetrate, a rising mean-charge state causes a rapid decrease in the inter-jet ion collision length. Finally, the interaction becomes collisional and the jets stagnate, eventually producing structures consistent with collisional shocks. These experimental observations can aid in the validation of plasma collisionality and ionization models for plasmas with complex equations of state.

  17. Investigation of the performance characteristics of a plasma synthetic jet actuator based on a quantitative Schlieren method

    NASA Astrophysics Data System (ADS)

    Zong, Hao-hua; Wu, Yun; Song, Hui-min; Jia, Min; Liang, Hua; Li, Ying-hong; Zhang, Zhi-bo

    2016-05-01

    A quantitative Schlieren method is developed to calculate the density field of axisymmetric flows. With this method, the flow field structures of plasma synthetic jets are analysed in detail. Major performance parameters, including the maximum density increase behind the shock wave, the expelled mass per pulse and the impulse, are obtained to evaluate the intensity of the shock wave and the jet. A high-density but low-velocity jet issues out of the cavity after the precursor shock wave, with a vortex ring at the wave front. The vortex ring gradually lags behind the center jet during the propagation, and its profile resembles a pair of kidneys in shape. After the jet terminates, the vortex ring breaks down and the whole density field is separated into two regions. In one period, the jet front velocity first increases and then decreases, with a maximum value of 270 m s‑1. The precursor shock wave velocity decays quickly from 370 m s‑1 to 340 m s‑1 in the first 50 μs. The variation in the maximum density rise behind the precursor shock wave is similar to that of the jet front velocity. The averaged exit density drops sharply at around 50 μs and then gradually rises. The maximum mass flow rate is about 0.35 g s‑1, and the total expelled mass in one period occupies 26% of the initial cavity gas mass. The impulse produced in the jet stage is estimated to be 5 μN s–1. The quantitative Schlieren method developed can also be used in the research of other compressible axisymmetric flows.

  18. Effects of air transient spark discharge and helium plasma jet on water, bacteria, cells, and biomolecules.

    PubMed

    Hensel, Karol; Kučerová, Katarína; Tarabová, Barbora; Janda, Mário; Machala, Zdenko; Sano, Kaori; Mihai, Cosmin Teodor; Ciorpac, Mitică; Gorgan, Lucian Dragos; Jijie, Roxana; Pohoata, Valentin; Topala, Ionut

    2015-01-01

    Atmospheric pressure DC-driven self-pulsing transient spark (TS) discharge operated in air and pulse-driven dielectric barrier discharge plasma jet (PJ) operated in helium in contact with water solutions were used for inducing chemical effects in water solutions, and the treatment of bacteria (Escherichia coli), mammalian cells (Vero line normal cells, HeLa line cancerous cells), deoxyribonucleic acid (dsDNA), and protein (bovine serum albumin). Two different methods of water solution supply were used in the TS: water electrode system and water spray system. The effects of both TS systems and the PJ were compared, as well as a direct exposure of the solution to the discharge with an indirect exposure to the discharge activated gas flow. The chemical analysis of water solutions was performed by using colorimetric methods of UV-VIS absorption spectrophotometry. The bactericidal effects of the discharges on bacteria were evaluated by standard microbiological plate count method. Viability, apoptosis and cell cycle were assessed in normal and cancerous cells. Viability of cells was evaluated by trypan blue exclusion test, apoptosis by Annexin V-FITC/propidium iodide assay, and cell cycle progression by propidium iodide/RNase test. The effect of the discharges on deoxyribonucleic acid and protein were evaluated by fluorescence and UV absorption spectroscopy. The results of bacterial and mammalian cell viability, apoptosis, and cell cycle clearly show that cold plasma can inactivate bacteria and selectively target cancerous cells, which is very important for possible future development of new plasma therapeutic strategies in biomedicine. The authors found that all investigated bio-effects were stronger with the air TS discharge than with the He PJ, even in indirect exposure. PMID:25947389

  19. Production of nitric/nitrous oxide by an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Douat, C.; Hübner, S.; Engeln, R.; Benedikt, J.

    2016-04-01

    Absolute densities of nitrous species were studied in an atmospheric pressure RF plasma jet. The measurement of NO and N2O densities has been performed mainly by means of ex situ quantum-cascade laser absorption spectroscopy via a multi-pass cell in Herriot configuration. The dependence of the species’ production on individual parameters such as power, flow and oxygen, nitrogen and water admixture is shown. NO and N2O densities are found to increase with absorbed power, while an increase in the gas flow induces a decrease of these densities due to a reduction in residence time of the gas in the plasma. Actually, a change of these two parameters, absorbed power and gas flow, induces a variation of energy density. The higher energy density, the higher NO and N2O densities. The NO and N2O densities are strongly gas mixture dependent. A change of that parameter allows to choose between a NO-rich or a N2O-rich regime. NO and N2O densities increase as a function of the N2 admixture, while increasing oxygen, above a minimum value, reduces the densities of both NO and N2O. When adding water instead of oxygen to the gas mixture the reduction in the NO density is much less. For maximal NO and N2O formation a ratio of about He/N2/O2  =  99.5/0.36/0.07 is found to be the most efficient in the μ-APPJ. However, it was found that the absorbed power in the plasma always reduces with increasing admixtures. The validation of the results obtained with quantum-cascade absorption spectroscopy with mass spectrometry shows how the two measurement techniques can complement each other. Finally a comparison of our results and others works is presented.

  20. Surface pretreatment of plastics with an atmospheric pressure plasma jet - Influence of generator power and kinematics

    SciTech Connect

    Moritzer, E. Leister, C.

    2014-05-15

    The industrial use of atmospheric pressure plasmas in the plastics processing industry has increased significantly in recent years. Users of this treatment process have the possibility to influence the target values (e.g. bond strength or surface energy) with the help of kinematic and electrical parameters. Until now, systematic procedures have been used with which the parameters can be adapted to the process or product requirements but only by very time-consuming methods. For this reason, the relationship between influencing values and target values will be examined based on the example of a pretreatment in the bonding process with the help of statistical experimental design. Because of the large number of parameters involved, the analysis is restricted to the kinematic and electrical parameters. In the experimental tests, the following factors are taken as parameters: gap between nozzle and substrate, treatment velocity (kinematic data), voltage and duty cycle (electrical data). The statistical evaluation shows significant relationships between the parameters and surface energy in the case of polypropylene. An increase in the voltage and duty cycle increases the polar proportion of the surface energy, while a larger gap and higher velocity leads to lower energy levels. The bond strength of the overlapping bond is also significantly influenced by the voltage, velocity and gap. The direction of their effects is identical with those of the surface energy. In addition to the kinematic influences of the motion of an atmospheric pressure plasma jet, it is therefore especially important that the parameters for the plasma production are taken into account when designing the pretreatment processes.