Science.gov

Sample records for air plasma produced

  1. Quasi-steady-state air plasma channel produced by a femtosecond laser pulse sequence

    PubMed Central

    Lu, Xin; Chen, Shi-You; Ma, Jing-Long; Hou, Lei; Liao, Guo-Qian; Wang, Jin-Guang; Han, Yu-Jing; Liu, Xiao-Long; Teng, Hao; Han, Hai-Nian; Li, Yu-Tong; Chen, Li-Ming; Wei, Zhi-Yi; Zhang, Jie

    2015-01-01

    A long air plasma channel can be formed by filamentation of intense femtosecond laser pulses. However, the lifetime of the plasma channel produced by a single femtosecond laser pulse is too short (only a few nanoseconds) for many potential applications based on the conductivity of the plasma channel. Therefore, prolonging the lifetime of the plasma channel is one of the key challenges in the research of femtosecond laser filamentation. In this study, a unique femtosecond laser source was developed to produce a high-quality femtosecond laser pulse sequence with an interval of 2.9 ns and a uniformly distributed single-pulse energy. The metre scale quasi-steady-state plasma channel with a 60–80 ns lifetime was formed by such pulse sequences in air. The simulation study for filamentation of dual femtosecond pulses indicated that the plasma channel left by the previous pulse was weakly affected the filamentation of the next pulse in sequence under our experimental conditions. PMID:26493279

  2. Air core poloidal magnetic field system for a toroidal plasma producing device

    DOEpatents

    Marcus, Frederick B.

    1978-01-01

    A poloidal magnetics system for a plasma producing device of toroidal configuration is provided that reduces both the total volt-seconds requirement and the magnitude of the field change at the toroidal field coils. The system utilizes an air core transformer wound between the toroidal field (TF) coils and the major axis outside the TF coils. Electric current in the primary windings of this transformer is distributed and the magnetic flux returned by air core windings wrapped outside the toroidal field coils. A shield winding that is closely coupled to the plasma carries a current equal and opposite to the plasma current. This winding provides the shielding function and in addition serves in a fashion similar to a driven conducting shell to provide the equilibrium vertical field for the plasma. The shield winding is in series with a power supply and a decoupling coil located outside the TF coil at the primary winding locations. The present invention requires much less energy than the usual air core transformer and is capable of substantially shielding the toroidal field coils from poloidal field flux.

  3. Spectroscopic analysis of the excitation transfer from background air to diffusing aluminum laser produced plasma

    SciTech Connect

    Ribiere, M.; Cheron, B. G.; Karabourniotis, D.

    2009-04-15

    During the relaxation of the plasma plume generated by laser ablation of an aluminum target, a pronounced intensity enhancement is observed at the central wavelength of the 396.15 nm self-reversed resonant line. This spectral special feature is analyzed and related to the interaction of the plasma edge with the background air excited by the shockwave, prompt electrons, and extreme ultraviolet radiation produced at the earliest times of the ablation. In this article, the electron density, the aluminum ground state, and resonant level populations are determined from the fitting of the 396.15 nm calculated line profile to the experimental one at two background pressures (100 and 1000 Pa). The evolution of these densities is derived from experiments performed at delays, after the laser pulse arrival, ranging from 120 to 180 ns.

  4. Dust particle charge screening in the dry-air plasma produced by an external ionization source

    SciTech Connect

    Derbenev, I. N.; Filippov, A. V.

    2015-08-15

    The ionic composition of the plasma produced by an external ionization source in dry air at atmospheric pressure and room temperature and the screening of the electric field of a dust particle in such a plasma have been investigated. The point sink model based on the diffusion-drift approximation has been used to solve the screening problem. We have established that the main species of ions in the plasma under consideration are O{sub 4}{sup +}, O{sub 2}{sup -}, and O{sub 4}{sup -} and that the dust particle potential distribution is described by a superposition of four exponentials with four different constants. We show that the first constant coincides with the inverse Debye length, the second is described by the inverse ambipolar diffusion length of the positive and negative plasma components in the characteristic time of their recombination, the third is determined by the conversion of negative ions, and the fourth is determined by the attachment and recombination of electrons and diatomic ions.

  5. Production of geopolymers using glass produced from DC plasma treatment of air pollution control (APC) residues.

    PubMed

    Kourti, Ioanna; Rani, D Amutha; Deegan, D; Boccaccini, A R; Cheeseman, C R

    2010-04-15

    Air pollution control (APC) residues are the hazardous waste produced from cleaning gaseous emissions at energy-from-waste (EfW) facilities processing municipal solid waste (MSW). APC residues have been blended with glass-forming additives and treated using DC plasma technology to produce a high calcium alumino-silicate glass. This research has investigated the optimisation and properties of geopolymers prepared from this glass. Work has shown that high strength geopolymers can be formed and that the NaOH concentration of the activating solution significantly affects the properties. The broad particle size distribution of the APC residue glass used in these experiments results in a microstructure that contains unreacted glass particles included within a geopolymer binder phase. The high calcium content of APC residues may cause the formation of some amorphous calcium silicate hydrate (C-S-H) gel. A mix prepared with S/L=3.4, Si/Al=2.6 and [NaOH]=6M in the activating solution, produced high strength geopolymers with compressive strengths of approximately 130 MPa. This material had high density (2070 kg/m(3)) and low porosity. The research demonstrates for the first time that glass derived from DC plasma treatment of APC residues can be used to form high strength geopolymer-glass composites that have potential for use in a range of applications.

  6. Kinetic-energy structure of a laser-produced-plasma channel in air

    NASA Astrophysics Data System (ADS)

    Shu, Xiao-Fang; Yu, Cheng-Xin; Li, Wei; Liu, Shi-Bing

    2015-12-01

    In this paper, we propose a method to calculate the fine structure of kinetic energy of laser-produced plasma, which bridges the two parts of researches of plasma channel usually studied independently of each other, i.e., the extension of the length of plasma filament and the prolongation of the lifetime of plasma channel generated by the laser pulse. The kinetic energy structure of the plasma channel is calculated by solving the motion equation of ionized electrons and utilizing the ionization rate as the weighting factor. With the study on the laser intensity, we analyze the formation mechanisms of the kinetic energy structure. This work holds great promise for optimizing the initial conditions of the evolutions of plasma channel after the laser pulse.

  7. Spatial diagnostics of the laser-produced tin plasma in air

    NASA Astrophysics Data System (ADS)

    Iqbal, Javed; Ahmed, R.; Rafique, M.; Anwar-ul-Haq, M.; Baig, M. A.

    2016-07-01

    We present here new experimental studies on the laser-produced tin plasma generated by focusing the beam of a Q-switched Nd:YAG laser (532 nm) on the sample in air at atmospheric pressure. The optical emission spectra were recorded with a set of five spectrometers covering the spectral range from 200-720 nm. The electron temperature has been calculated to be about (10 600  ±  600) K using three methods; the two-line ratio, Boltzmann plot and the Saha-Boltzmann plot method, whereas the electron number density of about (9.0  ±  0.8)  ×  1016 cm-3 has been calculated using the Stark broadened line profiles of tin lines and the hydrogen Hα-line. Furthermore, the branching fractions have been deduced for 15 spectral lines of the 5p5d  →  5p2 transition array in tin, whereas the absolute values of the transition probabilities have been calculated by combining the experimental branching fractions with the lifetimes of the excited levels. Our measured values are compared with those reported in the literature and NIST data base, showing good agreement.

  8. Experimental study of the behavior of two laser produced plasmas in air

    SciTech Connect

    Yang, Zefeng; Wei, Wenfu; Han, Jiaxun; Wu, Jian Li, Xingwen; Jia, Shenli

    2015-07-15

    The interactions among two laser ablated Al plasmas and their shock wave fronts (SWFs) induced by double laser pulses in air were studied experimentally. The evolution processes, including the expansion and interaction of the two plasmas and their shocks, were investigated by laser shadowgraphs, schlieren images, and interferograms. Remarkably, the distribution of the compressed air and the laser plasmas during the colliding process was clearly obtained using the Mach-Zehnder interferometer. From the refractive index profiles, typical plasmas density and gas density behind the shock front were estimated as ∼5.2 × 10{sup 18 }cm{sup −3} and ∼2.4 × 10{sup 20 }cm{sup −3}. A stagnation layer formed by the collision of gas behind the shock front is observed. The SWFs propagated, collided, and reflected with a higher velocity than plasmas. The results indicated that the slower plasma collided at middle, leading to the formation of the soft stagnation.

  9. Measurement of transient force produced by a propagating arc magnetohydrodynamic plasma actuator in quiescent atmospheric air

    NASA Astrophysics Data System (ADS)

    Choi, Young Joon; Sirohi, Jayant; Raja, Laxminarayan L.

    2015-10-01

    An experimental study was conducted on a magnetohydrodynamic plasma actuator consisting of two parallel, six inch long, copper electrodes flush mounted on an insulating ceramic plate. An electrical arc is generated by a  ∼1 kA current pulse at  ∼100 V across the electrodes. A self-induced Lorentz force drives the arc along the electrodes. The motion of the arc induces flow in the surrounding air through compression as well as entrainment, and generates a transient force, about  ∼4 ms in duration. Experiments were performed on a prototype actuator in quiescent atmospheric air to characterize the motion of the arc and the momentum transferred to the surrounding air. Measurements included transient force and total impulse generated by the actuator as well as the armature voltage and current. The arc shape and transit velocity were determined by high-speed imaging. A peak force of 0.4 N imparting an impulse of 0.68 mN-s was measured for a peak current of 1.2 kA. The force scaled with the square of the armature current and the impulse scaled linearly with the spent capacitor energy. The results provide insight into the mechanisms of body force generation and momentum transfer of a magnetohydrodynamic plasma actuator.

  10. Directed transfer of microwave radiation in sliding-mode plasma waveguides produced by ultraviolet laser in atmospheric air.

    PubMed

    Zvorykin, Vladimir D; Ionin, Andrei A; Levchenko, Alexei O; Seleznev, Leonid V; Sinitsyn, Dmitrii V; Smetanin, Igor' V; Ustinovskii, Nikolai N; Shutov, Alexei V

    2014-11-01

    Experiments have been performed at hybrid Ti:sapphire/KrF laser facility GARPUN-MTW to develop a novel technique to create a hollow-core sliding-mode plasma-filament waveguide for directed transfer of microwave radiation. Efficient multiphoton air ionization was produced by a train of picosecond 1-TW UV pulses at 248 nm wavelength, or by amplitude-modulated 100 ns pulse combining a short-pulse train with a free-running 1-GW pulse, which detached electrons off O2- ions. Multiple filamentation of UV laser radiation in air was observed, and filamentation theory based on resonance-enhanced ionization was developed to explain the experimental results.

  11. The interaction of polarized microwaves with planar arrays of femtosecond laser-produced plasma filaments in air

    SciTech Connect

    Marian, Anca; El Morsli, Mbark; Vidal, Francois; Payeur, Stephane; Kieffer, Jean-Claude; Chateauneuf, Marc; Theberge, Francis; Dubois, Jacques

    2013-02-15

    The interaction of polarized microwaves with subwavelength arrays of parallel plasma filaments, such as those produced by the propagation of high-power femtosecond laser pulses in ambient air, was investigated by calculating the reflection and transmission coefficients as a function of the incidence angles using the finite-difference time-domain (FDTD) method. The time evolution of these coefficients was calculated and compared with experiments. It is found that the plasma filaments array becomes transparent when the polarization of the microwave radiation is perpendicular to the filaments axis, regardless the incidence angle of the microwave with respect to the filaments, except near grazing incidence. Increasing the filaments electron density or diameter, or decreasing the electron collision frequency or filaments spacing, decreases the transmission and increases the reflection. Transmission decreases when increasing the number of filament layers while reflection remains unchanged as the number of filament layers exceeds a given number ({approx}3 in our case). Transmission slightly increases when disorder is introduced in the filament arrays. The detailed calculation results are compared with those obtained from the simple birefringent slab model, which provides a convenient framework to calculate approximately the properties of filament arrays.

  12. Lifecycle of laser-produced air sparks

    SciTech Connect

    Harilal, S. S. Brumfield, B. E.; Phillips, M. C.

    2015-06-15

    We investigated the lifecycle of laser-generated air sparks or plasmas using multiple plasma diagnostic tools. The sparks were generated by focusing the fundamental radiation from an Nd:YAG laser in air, and studies included early and late time spark dynamics, decoupling of the shock wave from the plasma core, emission from the spark kernel, cold gas excitation by UV radiation, shock waves produced by the air spark, and the spark's final decay and turbulence formation. The shadowgraphic and self-emission images showed similar spark morphology at earlier and late times of its lifecycle; however, significant differences are seen in the midlife images. Spectroscopic studies in the visible region showed intense blackbody-type radiation at early times followed by clearly resolved ionic, atomic, and molecular emission. The detected spectrum at late times clearly contained emission from both CN and N{sub 2}{sup +}. Additional spectral features have been identified at late times due to emission from O and N atoms, indicating some degree of molecular dissociation and excitation. Detailed spatially and temporally resolved emission analysis provides insight about various physical mechanisms leading to molecular and atomic emission by air sparks, including spark plasma excitation, heating of cold air by UV radiation emitted by the spark, and shock-heating.

  13. Antimicrobial Applications of Ambient--Air Plasmas

    NASA Astrophysics Data System (ADS)

    Pavlovich, Matthew John

    The emerging field of plasma biotechology studies the applications of the plasma phase of matter to biological systems. "Ambient-condition" plasmas created at or near room temperature and atmospheric pressure are especially promising for biomedical applications because of their convenience, safety to patients, and compatibility with existing medical technology. Plasmas can be created from many different gases; plasma made from air contains a number of reactive oxygen and nitrogen species, or RONS, involved in various biological processes, including immune activity, signaling, and gene expression. Therefore, ambient-condition air plasma is of particular interest for biological applications. To understand and predict the effects of treating biological systems with ambient-air plasma, it is necessary to characterize and measure the chemical species that these plasmas produce. Understanding both gaseous chemistry and the chemistry in plasma-treated aqueous solution is important because many biological systems exist in aqueous media. Existing literature about ambient-air plasma hypothesizes the critical role of reactive oxygen and nitrogen species; a major aim of this dissertation is to better quantify RONS by produced ambient-air plasma and understand how RONS chemistry changes in response to different plasma processing conditions. Measurements imply that both gaseous and aqueous chemistry are highly sensitive to operating conditions. In particular, chemical species in air treated by plasma exist in either a low-power ozone-dominated mode or a high-power nitrogen oxide-dominated mode, with an unstable transition region at intermediate discharge power and treatment time. Ozone (O3) and nitrogen oxides (NO and NO2, or NOx) are mutually exclusive in this system and that the transition region corresponds to the transition from ozone- to nitrogen oxides-mode. Aqueous chemistry agrees well with to air plasma chemistry, and a similar transition in liquid-phase composition

  14. Evolution of a plasma vortex in air.

    PubMed

    Tsai, Cheng-Mu; Chu, Hong-Yu

    2016-01-01

    We report the generation of a vortex-shaped plasma in air by using a capacitively coupled dielectric barrier discharge system. We show that a vortex-shaped plasma can be produced inside a helium gas vortex and is capable of propagating for 3 cm. The fluctuation of the plasma ring shows a scaling relation with the Reynolds number of the vortex. The transient discharge reveals the property of corona discharge, where the conducting channel within the gas vortex and the blur plasma emission are observed at each half voltage cycle. PMID:26871181

  15. Evolution of a plasma vortex in air.

    PubMed

    Tsai, Cheng-Mu; Chu, Hong-Yu

    2016-01-01

    We report the generation of a vortex-shaped plasma in air by using a capacitively coupled dielectric barrier discharge system. We show that a vortex-shaped plasma can be produced inside a helium gas vortex and is capable of propagating for 3 cm. The fluctuation of the plasma ring shows a scaling relation with the Reynolds number of the vortex. The transient discharge reveals the property of corona discharge, where the conducting channel within the gas vortex and the blur plasma emission are observed at each half voltage cycle.

  16. Air plasma jet with hollow electrodes at atmospheric pressure

    SciTech Connect

    Hong, Yong Cheol; Uhm, Han Sup

    2007-05-15

    Atmospheric-pressure plasma jet with air is produced through hollow electrodes and dielectric with a hole of 1 mm diam. The plasma jet device is operated by injecting pressurized air into the electrode hole. The air plasma jet device at average powers less than 5 W exhibits a cold plasma jet of about 2 cm in length and near the room temperature, being low enough to treat thermally sensitive materials. Preliminary studies on the discharge characteristics and application tests are also presented by comparing the air plasma jet with the nitrogen and argon plasma jet.

  17. Air plasma jet with hollow electrodes at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Hong, Yong Cheol; Uhm, Han Sup

    2007-05-01

    Atmospheric-pressure plasma jet with air is produced through hollow electrodes and dielectric with a hole of 5W exhibits a cold plasma jet of about 2cm in length and near the room temperature, being low enough to treat thermally sensitive materials. Preliminary studies on the discharge characteristics and application tests are also presented by comparing the air plasma jet with the nitrogen and argon plasma jet.

  18. Air stripping for treatment of produced water

    SciTech Connect

    Fang, C.S.; Lin, J.H.

    1988-05-01

    In a laboratory study, air stripping shows a promising potential for treatment of produced water to meet new government regulations on total organic carbon (TOC). Reservoir hydrocarbons dissolved in water, such as volatile paraffins and aromatics, can be removed by air stripping through interphase mass transfer. However, air stripping cannot remove many chemicals added to crude oil by the operator.

  19. Radiofrequency plasma antenna generated by femtosecond laser filaments in air

    SciTech Connect

    Brelet, Y.; Houard, A.; Point, G.; Prade, B.; Carbonnel, J.; Andre, Y.-B.; Mysyrowicz, A.; Arantchouk, L.; Pellet, M.

    2012-12-24

    We demonstrate tunable radiofrequency emission from a meter-long linear plasma column produced in air at atmospheric pressure. A short-lived plasma column is initially produced by femtosecond filamentation and subsequently converted into a long-lived discharge column by application of an external high voltage field. Radiofrequency excitation is fed to the plasma by induction and detected remotely as electromagnetic radiation by a classical antenna.

  20. High beta plasma operation in a toroidal plasma producing device

    DOEpatents

    Clarke, John F.

    1978-01-01

    A high beta plasma is produced in a plasma producing device of toroidal configuration by ohmic heating and auxiliary heating. The plasma pressure is continuously monitored and used in a control system to program the current in the poloidal field windings. Throughout the heating process, magnetic flux is conserved inside the plasma and the distortion of the flux surfaces drives a current in the plasma. As a consequence, the total current increases and the poloidal field windings are driven with an equal and opposing increasing current. The spatial distribution of the current in the poloidal field windings is determined by the plasma pressure. Plasma equilibrium is maintained thereby, and high temperature, high beta operation results.

  1. Laser-produced plasmas in medicine

    SciTech Connect

    Gitomer, S.J. ); Jones, R.D. . Applied Theoretical Physics Div.)

    1991-12-01

    The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photodynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper the authors examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. We consider examples of the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation), and in cardiology and vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented, along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included.

  2. Laser-produced plasmas in medicine

    SciTech Connect

    Gitomer, S.J.; Jones, R.D.

    1990-01-01

    The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper, we examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the application at hand to succeed. We consider examples of the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation) and in cardiology and vascular surgery (e.g., laser ablation and removal of fibro-fatty and calcified arterial plaque). Experimental data are presented along with some results from computer simulations of the phenomena. Comments on future directions in these areas are included. 63 refs.

  3. Parametric instabilities in helicon-produced plasmas

    SciTech Connect

    Aliev, Yu.M.; Kraemer, M.

    2005-07-15

    Parametric instabilities arising in the pump field of a helicon wave are analyzed for typical parameters of helicon-produced plasmas. The pump wavenumber parallel to the magnetic field is assumed to be finite according to recent experimental findings obtained on a high-density helicon discharge. The parametric decay of the helicon pump wave into ion-sound and Trivelpiece-Gould waves is investigated. The approach takes into account that the damping rate of the Trivelpiece-Gould wave is generally much higher than the ion-sound frequency. The theoretical results are in agreement with the growth rates and thresholds of this instability, as well as the dispersion properties of the decay waves observed in helicon experiments. Estimates of the level of the decay parametric turbulence turn out to be sufficiently high to account for the strong absorption observed in helicon-produced plasmas.

  4. Adventures in Laser Produced Plasma Research

    SciTech Connect

    Key, M

    2006-01-13

    In the UK the study of laser produced plasmas and their applications began in the universities and evolved to a current system where the research is mainly carried out at the Rutherford Appleton Laboratory Central Laser Facility ( CLF) which is provided to support the universities. My own research work has been closely tied to this evolution and in this review I describe the history with particular reference to my participation in it.

  5. Air-Plasma Bullets Propagating Inside Microcapillaries and in Ambient Air

    NASA Astrophysics Data System (ADS)

    Lacoste, Deanna A.; Bourdon, Anne; Kuribara, Koichi; Urabe, Keiichiro; Stauss, Sven; Terashima, Kazuo

    2014-10-01

    We report on the characterization of air-plasma bullets formed inside microcapillary tubes and in ambient air, obtained without the use of inert or noble gases. The bullets are produced by nanosecond discharges, applied at 1 kHz in a dielectric barrier discharge configuration. The anode consists of a tungsten wire with a 50- μm diameter, centered in the microcapillary, while the cathode is a silver ring, fixed on the outer surface of the fused silica tube. The gap distance is kept constant at 1.35 mm. The microcapillary is fed with a 4-sccm flow of air at atmospheric pressure. In the tubes and in ambient air, the propagation of air plasma bullets is observed. The temporal evolution of the bullet propagation has been studied with the aid of an ICCD camera. The effect of the applied voltage (from 5.2 to 8.2 kV) and the inner diameter of the microcapillaries (from 100 to 500 μm) on the discharge dynamics are investigated. Inside the tubes, while the topology of the bullets seems to be strongly dependent on the diameter, their velocity (on the order of 1 to 5 ×105 ms-1) is only a function of the applied voltage. In ambient air, the air-plasma bullets propagate at a velocity of 1 . 25 ×105 ms-1. Possible mechanisms for the propagation of air-plasma bullets in ambient air are discussed.

  6. Infrared Signature Masking by Air Plasma Radiation

    NASA Technical Reports Server (NTRS)

    Kruger, Charles H.; Laux, C. O.

    2001-01-01

    This report summarizes the results obtained during a research program on the infrared radiation of air plasmas conducted in the High Temperature Gasdynamics Laboratory at Stanford University under the direction of Professor Charles H. Kruger, with Dr. Christophe O. Laux as Associate Investigator. The goal of this research was to investigate the masking of infrared signatures by the air plasma formed behind the bow shock of high velocity missiles. To this end, spectral measurements and modeling were made of the radiation emitted between 2.4 and 5.5 micrometers by an atmospheric pressure air plasma in chemical and thermal equilibrium at a temperature of approximately 3000 K. The objective was to examine the spectral emission of air species including nitric oxide, atomic oxygen and nitrogen lines, molecular and atomic continua, as well as secondary species such as water vapor or carbon dioxide. The cold air stream injected in the plasma torch contained approximately 330 parts per million of CO2, which is the natural CO2 concentration in atmospheric air at room temperatures, and a small amount of water vapor with an estimated mole fraction of 3.8x10(exp -4).

  7. Producing Hydrogen by Plasma Pyrolysis of Methane

    NASA Technical Reports Server (NTRS)

    Atwater, James; Akse, James; Wheeler, Richard

    2010-01-01

    Plasma pyrolysis of methane has been investigated for utility as a process for producing hydrogen. This process was conceived as a means of recovering hydrogen from methane produced as a byproduct of operation of a life-support system aboard a spacecraft. On Earth, this process, when fully developed, could be a means of producing hydrogen (for use as a fuel) from methane in natural gas. The most closely related prior competing process - catalytic pyrolysis of methane - has several disadvantages: a) The reactor used in the process is highly susceptible to fouling and deactivation of the catalyst by carbon deposits, necessitating frequent regeneration or replacement of the catalyst. b) The reactor is highly susceptible to plugging by deposition of carbon within fixed beds, with consequent channeling of flow, high pressure drops, and severe limitations on mass transfer, all contributing to reductions in reactor efficiency. c) Reaction rates are intrinsically low. d) The energy demand of the process is high.

  8. Plasma treatment for producing electron emitters

    DOEpatents

    Coates, Don Mayo; Walter, Kevin Carl

    2001-01-01

    Plasma treatment for producing carbonaceous field emission electron emitters is disclosed. A plasma of ions is generated in a closed chamber and used to surround the exposed surface of a carbonaceous material. A voltage is applied to an electrode that is in contact with the carbonaceous material. This voltage has a negative potential relative to a second electrode in the chamber and serves to accelerate the ions toward the carbonaceous material and provide an ion energy sufficient to etch the exposed surface of the carbonaceous material but not sufficient to result in the implantation of the ions within the carbonaceous material. Preferably, the ions used are those of an inert gas or an inert gas with a small amount of added nitrogen.

  9. Air plasma treatment of liquid covered tissue: long timescale chemistry

    NASA Astrophysics Data System (ADS)

    Lietz, Amanda M.; Kushner, Mark J.

    2016-10-01

    Atmospheric pressure plasmas have shown great promise for the treatment of wounds and cancerous tumors. In these applications, the sample is usually covered by a thin layer of a biological liquid. The reactive oxygen and nitrogen species (RONS) generated by the plasma activate and are processed by the liquid before the plasma produced activation reaches the tissue. The synergy between the plasma and the liquid, including evaporation and the solvation of ions and neutrals, is critical to understanding the outcome of plasma treatment. The atmospheric pressure plasma sources used in these procedures are typically repetitively pulsed. The processes activated by the plasma sources have multiple timescales—from a few ns during the discharge pulse to many minutes for reactions in the liquid. In this paper we discuss results from a computational investigation of plasma-liquid interactions and liquid phase chemistry using a global model with the goal of addressing this large dynamic range in timescales. In modeling air plasmas produced by a dielectric barrier discharge over liquid covered tissue, 5000 voltage pulses were simulated, followed by 5 min of afterglow. Due to the accumulation of long-lived species such as ozone and N x O y , the gas phase dynamics of the 5000th discharge pulse are different from those of the first pulse, particularly with regards to the negative ions. The consequences of applied voltage, gas flow, pulse repetition frequency, and the presence of organic molecules in the liquid on the gas and liquid reactive species are discussed.

  10. 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.

  11. 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.

  12. Spectroscopic Analysis and Thomson Scattering Diagnostics of Wire Produced Plasma

    NASA Astrophysics Data System (ADS)

    Plechaty, Christopher; Sotnikov, Vladimir; Main, Daniel; Caplinger, James; Wallerstein, Austin; Kim, Tony

    2014-10-01

    The Lower Hybrid Drift Instability (LHDI) in plasma is driven by the presence of inhomogeneities in density, temperature, or magnetic field (Krall 1971, Davidson 1977), and occurs in systems where the electrons are magnetized and the ions are effectively unmagnetized. The LHDI is thought to occur in magnetic reconnection (Huba 1977), and has also been investigated as a mitigation technique which can allow for communications to take place through the plasma formed around hypersonic aircraft (Sotnikov 2010). To further understand the phenomenology of the LHDI, we plan to carry out experiments at the Air Force Research Laboratory, in the newly formed Plasma Physics Sensors Laboratory. In experiment, a pulsed power generator is employed to produce plasma by passing current through single, or dual-wire configurations. To characterize the plasma, a Thomson scattering diagnostic is employed, along with a visible spectroscopy diagnostic. This work was performed under the auspices of the U.S. Department of Defense by Riverside Research under Contract BAA-FA8650-13-C-1539.

  13. Air plasma effect on dental disinfection

    SciTech Connect

    Duarte, S.; Murata, R. M.; Saxena, D.; Kuo, S. P.; Chen, C. Y.; Huang, K. J.; Popovic, S.

    2011-07-15

    A nonthermal low temperature air plasma jet is characterized and applied to study the plasma effects on oral pathogens and biofilms. Experiments were performed on samples of six defined microorganisms' cultures, including those of gram-positive bacteria and fungi, and on a cultivating biofilm sample of Streptococcus mutans UA159. The results show that the plasma jet creates a zone of microbial growth inhibition in each treated sample; the zone increases with the plasma treatment time and expands beyond the entire region directly exposed to the plasma jet. With 30s plasma treatment twice daily during 5 days of biofilm cultivation, its formation was inhibited. The viability of S. mutans cells in the treated biofilms dropped to below the measurable level and the killed bacterial cells concentrated to local regions as manifested by the fluorescence microscopy via the environmental scanning electron microscope. The emission spectroscopy of the jet indicates that its plasma effluent carries an abundance of reactive atomic oxygen, providing catalyst for the observed plasma effect.

  14. Air plasma effect on dental disinfection

    NASA Astrophysics Data System (ADS)

    Duarte, S.; Kuo, S. P.; Murata, R. M.; Chen, C. Y.; Saxena, D.; Huang, K. J.; Popovic, S.

    2011-07-01

    A nonthermal low temperature air plasma jet is characterized and applied to study the plasma effects on oral pathogens and biofilms. Experiments were performed on samples of six defined microorganisms' cultures, including those of gram-positive bacteria and fungi, and on a cultivating biofilm sample of Streptococcus mutans UA159. The results show that the plasma jet creates a zone of microbial growth inhibition in each treated sample; the zone increases with the plasma treatment time and expands beyond the entire region directly exposed to the plasma jet. With 30s plasma treatment twice daily during 5 days of biofilm cultivation, its formation was inhibited. The viability of S. mutans cells in the treated biofilms dropped to below the measurable level and the killed bacterial cells concentrated to local regions as manifested by the fluorescence microscopy via the environmental scanning electron microscope. The emission spectroscopy of the jet indicates that its plasma effluent carries an abundance of reactive atomic oxygen, providing catalyst for the observed plasma effect.

  15. Infrared Signature Masking by Air Plasma Radiation

    NASA Technical Reports Server (NTRS)

    Kruger, C. H.; Laux, C. O.

    1998-01-01

    Detailed measurements and modeling of the spectral emission of an atmospheric pressure air plasma at temperatures up to -3400 K have been made. The cold gas injected in the plasma torch contained an estimated mole fraction of water vapor of approximately 4.5 x 10(exp -3) and an estimated carbon dioxide mole fraction of approximately 3.3 x 10(exp -4). Under these conditions, the minimum level of air plasma emission is found to be between 3.9 and 4.15 microns. Outside this narrow region, significant spectral emission is detected that can be attributed to the fundamental and overtone bands of NO and OH, and to the v(sub 3) and the (v(sub 1)+v(sub 3)) bands Of CO2. Special attention was paid to the effects of ambient air absorption in the optical path between the plasma and the detector. Excellent quantitative agreement is obtained between the measured and simulated spectra, which are both on absolute intensity scales, thus lending confidence in the radiation models incorporated into NEQAIR2-IR over the course of this research program.

  16. Infrared Signature Masking by Air Plasma Radiation

    NASA Technical Reports Server (NTRS)

    Kruger, C. H.; Laux, C. O.

    1998-01-01

    This report describes progress during the second year of our research program on Infrared Signature Masking by Air Plasmas at Stanford University. This program is intended to investigate the masking of infrared signatures by the air plasma formed behind the bow shock of high velocity missiles. Our previous annual report described spectral measurements and modeling of the radiation emitted between 3.2 and 5.5 microns by an atmospheric pressure air plasma in chemical and thermal equilibrium at a temperature of approximately 3100 K. One of our goals was to examine the spectral emission of secondary species such as water vapor or carbon dioxide. The cold air stream injected in the plasma torch contained approximately 330 parts per million Of CO2, which is the natural CO2 concentration in atmospheric air at room temperature, and a small amount of water vapor with an estimated mole fraction of 3.8 x 10(exp -4). As can be seen from Figure 1, it was found that the measured spectrum exhibited intense spectral features due to the fundamental rovibrational bands of NO at 4.9 - 5.5 microns and the V(3) band of CO2 (antisymmetric stretch) at 4.2-4.8 microns. These observations confirmed the well-known fact that infrared signatures between 4.15 - 5.5 microns can be masked by radiative emission in the interceptor's bow-shock. Figure I also suggested that the range 3.2 - 4.15 microns did not contain any significant emission features (lines or continuum) that could mask IR signatures. However, the signal-to-noise level, close to one in that range, precluded definite conclusions. Thus, in an effort to further investigate the spectral emission in the range of interest to signature masking problem, new measurements were made with a higher signal-to-noise ratio and an extended wavelength range.

  17. The mass and speed dependence of meteor air plasma temperatures.

    PubMed

    Jenniskens, Peter; Laux, Christophe O; Wilson, Michael A; Schaller, Emily L

    2004-01-01

    The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

  18. The mass and speed dependence of meteor air plasma temperatures

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Laux, Christophe O.; Wilson, Michael A.; Schaller, Emily L.

    2004-01-01

    The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

  19. Experimental and theoretical study of artificial plasma layers produced by two intersecting beams in a chamber

    NASA Technical Reports Server (NTRS)

    Kuo, S. P.; Zhang, Y. S.

    1989-01-01

    The work done on the Bragg scattering of electromagnetic waves by microwave produced plasma layers is reported. Also summarized is the work accomplished on the propagation of high power microwave pulses in an air breakdown environment. Ongoing work on the theoretical model and numerical results of pulse propagation in air is also presented as are the results of studying the decay of plasma density and temperature.

  20. Air Plasma Source for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Henriques, J.; Tatarova, E.; Dias, F. M.; Ferreira, C. M.; Gordiets, B.; IPFN-IST, 1049-001 LX, Portugal Team; Lebedev Physical Institute of the Russian Academy of Sciences Team

    2011-10-01

    Plasma interactions with living matter are presently at the frontiers of plasma research and development. Plasmas contain numerous agents that influence biological activity. They provide essentially two types of biocidal species: reactive species, such as oxygen atoms that lead to lethality of micro-organisms through erosion, and UV radiation that can damage the DNA strands. In this work we investigate a surface wave (2.45 GHz) driven discharge plasma in air, with a small admixture of water vapor, as a source of ground state O(3P) oxygen atoms, NO molecules and UV radiation. A theoretical model describing both the wave driven discharge zone and its flowing afterglow is used to analyze the performance of this plasma source. The predicted plasma-generated NO(X) and O(3P) concentrations and NO(γ) radiation intensity along the source are presented and discussed as a function of the microwave power and water vapor percentage in the gas mixture. To validate the theoretical predictions, the relative concentrations of species have been determined by Mass Spectrometry, Fourier Transform Infrared Spectroscopy and Optical Spectroscopy. Acknowledgment: This work was funded by the Portuguese Foundation for Science and Technology, under research contract PTDC/FIS/108411/2008.

  1. Light source employing laser-produced plasma

    SciTech Connect

    Tao, Yezheng; Tillack, Mark S

    2013-09-17

    A system and a method of generating radiation and/or particle emissions are disclosed. In at least some embodiments, the system includes at least one laser source that generates a first pulse and a second pulse in temporal succession, and a target, where the target (or at least a portion the target) becomes a plasma upon being exposed to the first pulse. The plasma expand after the exposure to the first pulse, the expanded plasma is then exposed to the second pulse, and at least one of a radiation emission and a particle emission occurs after the exposure to the second pulse. In at least some embodiments, the target is a solid piece of material, and/or a time period between the first and second pulses is less than 1 microsecond (e.g., 840 ns).

  2. Surface Wave Driven Air-Water Plasmas

    NASA Astrophysics Data System (ADS)

    Tatarova, Elena; Henriques, Julio; Ferreira, Carlos

    2013-09-01

    The performance of a surface wave driven air-water plasma source operating at atmospheric pressure and 2.45 GHz has been analyzed. A 1D model has been developed in order to describe in detail the creation and loss processes of active species of interest and to provide a complete characterization of the axial structure of the source, including the discharge and the afterglow zones. The main electron creation channel was found to be the associative ionization process N +O -->NO+ + e. The NO(X) relative density in the afterglow plasma jet ranges from 1.2% to 1.6% depending on power and water percentage according to the model predictions and the measurements. Other types of species such as NO2 and nitrous acid HNO2 have also been detected by mass and FT-IR spectroscopy. Furthermore, high densities of O2(a1Δg) singlet delta oxygen molecules and OH radicals (1% and 5%, respectively) can be achieved in the discharge zone. In the late afterglow the O2(a1Δg) density is about 0.1% of the total density. The plasma source has a flexible operation and potential for channeling the energy in ways that maximize the density of active species of interest. This study was funded by the Foundation for Science and Technology, Portuguese Ministry of Education and Science, under the research contract PTDC/FIS/108411/2008.

  3. Plasma reforming and partial oxidation of hydrocarbon fuel vapor to produce synthesis gas and/or hydrogen gas

    DOEpatents

    Kong, Peter C.; Detering, Brent A.

    2003-08-19

    Methods and systems for treating vapors from fuels such as gasoline or diesel fuel in an internal combustion engine, to form hydrogen gas or synthesis gas, which can then be burned in the engine to produce more power. Fuel vapor, or a mixture of fuel vapor and exhaust gas and/or air, is contacted with a plasma, to promote reforming reactions between the fuel vapor and exhaust gas to produce carbon monoxide and hydrogen gas, partial oxidation reactions between the fuel vapor and air to produce carbon monoxide and hydrogen gas, or direct hydrogen and carbon particle production from the fuel vapor. The plasma can be a thermal plasma or a non-thermal plasma. The plasma can be produced in a plasma generating device which can be preheated by contact with at least a portion of the hot exhaust gas stream, thereby decreasing the power requirements of the plasma generating device.

  4. Plasma Reforming And Partial Oxidation Of Hydrocarbon Fuel Vapor To Produce Synthesis Gas And/Or Hydrogen Gas

    DOEpatents

    Kong, Peter C.; Detering, Brent A.

    2004-10-19

    Methods and systems are disclosed for treating vapors from fuels such as gasoline or diesel fuel in an internal combustion engine, to form hydrogen gas or synthesis gas, which can then be burned in the engine to produce more power. Fuel vapor, or a mixture of fuel vapor and exhaust gas and/or air, is contacted with a plasma, to promote reforming reactions between the fuel vapor and exhaust gas to produce carbon monoxide and hydrogen gas, partial oxidation reactions between the fuel vapor and air to produce carbon monoxide and hydrogen gas, or direct hydrogen and carbon particle production from the fuel vapor. The plasma can be a thermal plasma or a non-thermal plasma. The plasma can be produced in a plasma generating device which can be preheated by contact with at least a portion of the hot exhaust gas stream, thereby decreasing the power requirements of the plasma generating device.

  5. LASER PLASMA Investigation of the optical characteristics of a laser-produced plasma cloud expanding into a background gas

    NASA Astrophysics Data System (ADS)

    Annenkov, A. I.; Bessarab, A. V.; Galakhov, I. V.; Garanin, Sergey G.; Gusakov, A. V.; Zhidkov, N. V.; Zhmailo, V. A.; Izgorodin, V. M.; Kovalenko, V. P.; Krotov, V. A.; Mis'ko, V. V.; Novikova, E. A.; Starodubtsev, V. A.; Starodubtsev, K. V.; Statsenko, V. P.; Sungatullin, R. R.; Tachaev, G. V.; Sheremet'ev, Yu N.

    2010-12-01

    An investigation is made of the dynamics and visible-range luminosity of the plasma cloud produced behind the front of a shock wave in air at a pressure of 1 Torr. The shock wave was produced on introducing the radiation of the twelve-channel Iskra-5 laser facility with a total energy of ~2300 J into a hollow spherical plastic target of mass ~10-4 g. Experimental data are compared with simulations.

  6. Filter media properties of mineral fibres produced by plasma spray.

    PubMed

    Prasauskas, Tadas; Matulevicius, Jonas; Kliucininkas, Linas; Krugly, Edvinas; Valincius, Vitas; Martuzevicius, Dainius

    2016-01-01

    The purpose of this study was to determine the properties of fibrous gas filtration media produced from mineral zeolite. Fibres were generated by direct current plasma spray. The paper characterizes morphology, chemical composition, geometrical structure of elementary fibres, and thermal resistance, as well as the filtration properties of fibre media. The diameter of the produced elementary fibres ranged from 0.17 to 0.90 μm and the length ranged from 0.025 to 5.1 mm. The release of fibres from the media in the air stream was noticed, but it was minimized by hot-pressing the formed fibre mats. The fibres kept their properties up to the temperature of 956°C, while further increase in temperature resulted in the filter media becoming shrunk and brittle. The filtration efficiency of the prepared filter mats ranged from 95.34% to 99.99% for aerosol particles ranging in a size between 0.03 and 10.0 μm. Unprocessed fibre media showed the highest filtration efficiency when filtering aerosol particles smaller than 0.1 µm. Hot-pressed filters were characterized by the highest quality factor values, ranging from 0.021 to 0.064 Pa(-1) (average value 0.034 Pa(-1)).

  7. Z-Pinch Discharge in Laser Produced Plasma

    SciTech Connect

    Sterling, E.; Lunney, J. G.

    2010-10-08

    A fast coaxial electrical discharge, with relatively low current, was used to produce a Z-pinch effect in a laser produced aluminum plasma. The ion flux in the laser plasma was monitored with a Langmuir ion probe. The line density in the plasma column was controlled by using an aperture to select the portion of the laser plasma which enters the discharge cell. The Z-pinch dynamics were recorded using time-resolved imaging of the visible self-emission; the plasma was pinched to about one-third of the initial radius. Both the laser and Z-pinch plasmas were diagnosed using time-and space-resolved spectroscopy; substantial heating was observed. The measured behaviour of the pinch was compared with predictions of the slug model.

  8. Origin of 'energetic' ions from laser-produced plasmas.

    NASA Technical Reports Server (NTRS)

    Ehler, W.; Linlor, W. I.

    1973-01-01

    A fast-ion current peak, measured with an ion collector placed in the path of an expanding laser-produced plasma, was identified as carbon, nitrogen, and oxygen contaminants which originated from a tungsten target surface.

  9. Atmospheric pressure air-plasma jet evolved from microdischarges: Eradication of E. coli with the jet

    SciTech Connect

    Hong, Yong Cheol; Kang, Won Seok; Hong, Yoo Beom; Yi, Won Ju; Uhm, Han Sup

    2009-12-15

    An atmospheric-pressure air-plasma jet operating at 60 Hz ac is presented. A plasma jet with a length of 23 mm was produced by feeding air through a porous alumina dielectric installed between an outer electrode and a hollow inner electrode. Microdischarges in the porous alumina are ejected as a plasma jet from the outer electrode through a 1 mm hole, showing that the temperature of the jet decreases to a value close to the room temperature. The jet disinfects E. coli cells very effectively, eradicating them with an exposure of a few seconds to the jet flame.

  10. Laser produced plasma diagnostics by cavity ringdown spectroscopy and applications

    SciTech Connect

    Milosevic, S.

    2012-05-25

    Laser-produced plasmas have many applications for which detailed characterization of the plume is requested. Cavity ring-down spectroscopy is a versatile absorption method which provides data on the plume and its surroundings, with spatial and temporal resolution. The measured absorption line shapes contain information about angular and velocity distributions within the plume. In various plasmas we have observed molecules or metastable atoms which were not present in the emission spectra.

  11. Measurement of Heat Propagation in a Laser Produced Plasma

    SciTech Connect

    Gregori, G; Glenzer, S H; Knight, J; Niemann, C; Price, D; Froula, D H; Edwards, J; Town, R P J; Brantov, A; Bychenkov, V Y; Rozmus, W

    2003-08-22

    We present the observation of a nonlocal heat wave by measuring spatially and temporally resolved electron temperature profiles in a laser produced nitrogen plasma. Absolutely calibrated measurements have been performed by resolving the ion-acoustic wave spectra across the plasma volume with Thomson scattering. We find that the experimental electron temperature profiles disagree with flux-limited models, but are consistent with transport models that account for the nonlocal effects in heat conduction by fast electrons.

  12. Radiative heat transport instability in a laser produced inhomogeneous plasma

    SciTech Connect

    Bychenkov, V. Yu.; Rozmus, W.

    2015-08-15

    A laser produced high-Z plasma in which an energy balance is achieved due to radiation emission and radiative heat transfer supports ion acoustic instability. A linear dispersion relation is derived, and instability is compared to the radiation cooling instability [R. G. Evans, Plasma Phys. Controlled Fusion 27, 751 (1985)]. Under conditions of indirect drive fusion experiments, the driving term for the instability is the radiative heat flux and, in particular, the density dependence of the radiative heat conductivity. A specific example of thermal Bremsstrahlung radiation source has been considered. This instability may lead to plasma jet formation and anisotropic x-ray generation, thus affecting inertial confinement fusion related experiments.

  13. Measurements of plasma bremsstrahlung and plasma energy density produced by electron cyclotron resonance ion source plasmas

    NASA Astrophysics Data System (ADS)

    Noland, Jonathan David

    2011-12-01

    The goal of this dissertation was to gain an understanding on the relative importance of microwave power, neutral pressure, and magnetic field configuration on the behavior of the hot electrons within an Electron Cyclotron Resonance Ion Source (ECRIS) plasma. This was carried out through measurement of plasma bremsstrahlung with both NaI(Tl) (hv > 30 keV) and CdTe (2 keV < hv < 70 keV) x-ray detectors, and through measurement of the plasma energy density with a diamagnetic loop placed around the plasma chamber. We also examined the anisotropy in x-ray power by simultaneously measuring the x-ray spectra in two orthogonal directions: radially and axially, using NaI(Tl) detectors. We have seen that for a 6.4 GHz ECRIS, both the x-ray power produced by confined electrons and the plasma energy density behave logarithmically with microwave power. The x-ray flux created by electrons lost from the plasma, however, does not saturate. Thus, the small increase in plasma density that occurred at high microwave powers (> 150 W on a 6.4 GHz ECRIS) was accompanied by a large increase in total x-ray power. We suggest that the saturation of x-ray power and plasma energy density was due to rf-induced pitch-angle scattering of the electrons. X-ray power and plasma energy density were also shown to saturate with neutral pressure, and to increase nearly linearly as the gradient of the magnetic field in the resonance zone was decreased. All of these findings were in agreement with the theoretical models describing ECRIS plasmas. We have discussed the use of a diamagnetic loop as a means of exploring various plasma time scales on a relative basis. Specifically, we focused much of our attention on studying how changing ion source parameters, such as microwave power and neutral pressure, would effect the rise and decay of the integrated diamagnetic signal, which can be related to plasma energy density. We showed that increasing microwave power lowers the e-fold times at both the leading

  14. METHOD OF PRODUCING ENERGETIC PLASMA FOR NEUTRON PRODUCTION

    DOEpatents

    Bell, P.R.; Simon, A.; Mackin, R.J. Jr.

    1961-01-24

    A method is given for producing an energetic plasma for neutron production. An energetic plasma is produced in a small magnetically confined subvolume of the device by providing a selected current of energetic molecular ions at least greater than that required for producing a current of atomic ions sufficient to achieve "burnout" of neutral particles in the subvolume. The atomic ions are provided by dissociation of the molecular ions by an energetic arc discharge within the subvolume. After burnout, the arc discharge is terminated, the magnetic fields increased, and cold fuel feed is substituted for the molecular ions. After the subvolume is filled with an energetic plasma, the size of the magnetically confined subvolume is gradually increased until the entire device is filled with an energetic neutron producing plasma. The reactions which take place in the device to produce neutrons will generate a certain amount of heat energy which may be converted by the use of a conventional heat cycle to produce electrical energy.

  15. Terahertz generation in multiple laser-induced air plasmas

    SciTech Connect

    Chen, M.-K.; Kim, Jae Hun; Yang, C.-E.; Yin, Stuart Shizhuo; Hui Rongqing; Ruffin, Paul

    2008-12-08

    An investigation of the terahertz wave generation in multiple laser-induced air plasmas is presented. First, it is demonstrated that the intensity of the terahertz wave increases as the number of air plasmas increases. Second, the physical mechanism of this enhancement effect of the terahertz generation is studied by quantitatively measuring the intensity of the generated terahertz wave as a function of phase difference between adjacent air plasmas. It is found out that the superposition is the main mechanism to cause this enhancement. Thus, the results obtained in this paper not only provide a technique to generate stronger terahertz wave but also enable a better understanding of the mechanism of the terahertz generation in air plasma.

  16. Studies of Magnetic Reconnection in Colliding Laser-Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Rosenberg, Michael

    2013-10-01

    Novel images of magnetic fields and measurements of electron and ion temperatures have been obtained in the magnetic reconnection region of high- β, laser-produced plasmas. Experiments using laser-irradiated foils produce expanding, hemispherical plasma plumes carrying MG Biermann-battery magnetic fields, which can be driven to interact and reconnect. Thomson-scattering measurements of electron and ion temperatures in the interaction region of two colliding, magnetized plasmas show no thermal enhancement due to reconnection, as expected for β ~ 8 plasmas. Two different proton radiography techniques used to image the magnetic field structures show deformation, pileup, and annihilation of magnetic flux. High-resolution images reveal unambiguously reconnection-induced jets emerging from the interaction region and show instabilities in the expanding plasma plumes and supersonic, hydrodynamic jets due to the plasma collision. Quantitative magnetic flux data show that reconnection in experiments with asymmetry in the scale size, density, temperature, and plasma flow across the reconnection region occurs less efficiently than in similar, symmetric experiments. This result is attributed to disruption of the Hall mechanism mediating collisionless reconnection. The collision of plasmas carrying parallel magnetic fields has also been probed, illustrating the deformation of magnetic field structures in high-energy-density plasmas in the absence of reconnection. These experiments are particularly relevant to high- β reconnection environments, such as the magnetopause. This work was performed in collaboration with C. Li, F. Séguin, A. Zylstra, H. Rinderknecht, H. Sio, J. Frenje, and R. Petrasso (MIT), I. Igumenshchev, V. Glebov, C. Stoeckl, and D. Froula (LLE), J. Ross and R. Town (LLNL), W. Fox (UNH), and A. Nikroo (GA), and was supported in part by the NLUF, FSC/UR, U.S. DOE, LLNL, and LLE.

  17. Effect of glow discharge air plasma on grain crops seed

    SciTech Connect

    Dubinov, A.E.; Lazarenko, E.M.; Selemir, V.D.

    2000-02-01

    Oat and barley seeds have been exposed to both continuous and pulsed glow discharge plasmas in air to investigate the effects on germination and sprout growth. Statistical analysis was used to evaluate the effect of plasma exposure on the percentage germination and length of sprout growth. A stimulating effect of plasma exposure was found together with a strong dependence on whether continuous or pulsed discharges were used.

  18. Study of nanosecond laser-produced plasmas in atmosphere by spatially resolved optical emission spectroscopy

    SciTech Connect

    Wei, Wenfu; Wu, Jian; Li, Xingwen; Jia, Shenli; Qiu, Aici

    2013-09-21

    We investigate the evolution of the species from both the target and the air, and the plasma parameter distribution of the nanosecond laser-produced plasmas in atmospheric air. The technique used is spatially resolved optical emission spectroscopy. It is argued that the N II from the air, which is distributed over a wider region than the target species in the early stages of the discharge, is primarily formed by the shock wave. The ionized species have a larger expansion velocity than the excited atoms in the first ∼100 ns, providing direct evidence for space-charge effects. The electron density decreases with the distance from the target surface in the early stages of the discharge, and both the electron density and the excited temperature variation in the axial direction are found to become insignificant at later stages.

  19. Quantification of air plasma chemistry for surface disinfection

    NASA Astrophysics Data System (ADS)

    Pavlovich, Matthew J.; Clark, Douglas S.; Graves, David B.

    2014-12-01

    Atmospheric-pressure air plasmas, created by a variety of discharges, are promising sources of reactive species for the emerging field of plasma biotechnology because of their convenience and ability to operate at ambient conditions. One biological application of ambient-air plasma is microbial disinfection, and the ability of air plasmas to decontaminate both solid surfaces and liquid volumes has been thoroughly established in the literature. However, the mechanism of disinfection and which reactive species most strongly correlate with antimicrobial effects are still not well understood. We describe quantitative gas-phase measurements of plasma chemistry via infrared spectroscopy in confined volumes, focusing on air plasma generated via surface micro-discharge (SMD). Previously, it has been shown that gaseous chemistry is highly sensitive to operating conditions, and the measurements we describe here extend those findings. We quantify the gaseous concentrations of ozone (O3) and nitrogen oxides (NO and NO2, or NOx) throughout the established ‘regimes’ for SMD air plasma chemistry: the low-power, ozone-dominated mode; the high-power, nitrogen oxides-dominated mode; and the intermediate, unstable transition region. The results presented here are in good agreement with previously published experimental studies of aqueous chemistry and parameterized models of gaseous chemistry. The principal finding of the present study is the correlation of bacterial inactivation on dry surfaces with gaseous chemistry across these time and power regimes. Bacterial decontamination is most effective in ‘NOx mode’ and less effective in ‘ozone mode’, with the weakest antibacterial effects in the transition region. Our results underscore the dynamic nature of air plasma chemistry and the importance of careful chemical characterization of plasma devices intended for biological applications.

  20. Collimation of laser-produced plasmas using axial magnetic field

    SciTech Connect

    Roy, Amitava; Harilal, Sivanandan S.; Hassan, Syed M.; Endo, Akira; Mocek, Tomas; Hassanein, A.

    2015-06-01

    We investigated the expansion dynamics of laser-produced plasmas expanding into an axial magnetic field. Plasmas were generated by focusing 1.064 µm Nd:YAG laser pulses onto a planar tin target in vacuum and allowed to expand into a 0.5 T magnetic-filed where field lines were aligned along the plume expansion direction. Gated images employing intensified CCD showed focusing of the plasma plume, which were also compared with results obtained using particle-in-cell modelling methods. The estimated density and temperature of the plasma plumes employing emission spectroscopy revealed significant changes in the presence and absence of the 0.5T magnetic field. In the presence of the field, the electron temperature is increased with distance from the target, while the density showed opposite effects.

  1. Collision dynamics of laser produced carbon plasma plumes

    NASA Astrophysics Data System (ADS)

    Favre, M.; Ruiz, H. M.; Cortés, D.; Merello, F.; Bhuyan, H.; Veloso, F.; Wyndham, E.

    2016-05-01

    We present preliminary experimental observations of the collision processes between two orthogonal laser produced plasmas in a low pressure neutral gas background. A Nd:YAG laser, 340 mJ, 3.5 ns, at 1.06 μm, operating at 10 Hz, is used in the experiments. The main laser beam is divided in two beams by a 50% beam splitter, and then focused over two rotating graphite targets, with characteristic fluence 3.5 J/cm2. Experiments are conducted in a range from a base pressure of 0.3 mTorr, up to 50 mTorr argon. The dynamics of the laser plasmas is characterized by time resolved and time integrated optical emission spectroscopy (OES), with 20 ns and 10 ms time resolution, and 50 ns time resolved plasma imaging of visible plasma emission. Clear effects of the neutral gas background on the postcollision plasma dynamics are identified. The overall dynamics of the post-collision plasma is found to be consistent with high collisionality of the carbon plasma plumes, which results in full stagnation on collisioning.

  2. Towards laboratory produced relativistic electron–positron pair plasmas

    SciTech Connect

    Chen, Hui; Meyerhofer, D. D.; Wilks, S. C.; Cauble, R.; Dollar, F.; Falk, K.; Gregori, G.; Hazi, A.; Moses, E. I.; Murphy, C. D.; Myatt, J.; Park, J.; Seely, J.; Shepherd, R.; Spitkovsky, A.; Stoeckl, C.; Szabo, C. I.; Tommasini, R.; Zulick, C.; Beiersdorfer, P.

    2011-12-01

    We review recent experimental results on the path to producing electron–positron pair plasmas using lasers. Relativistic pair-plasmas and jets are believed to exist in many astrophysical objects and are often invoked to explain energetic phenomena related to Gamma Ray Bursts and Black Holes. On earth, positrons from radioactive isotopes or accelerators are used extensively at low energies (sub-MeV) in areas related to surface science positron emission tomography and basic antimatter science. Experimental platforms capable of producing the high-temperature pair-plasma and high-flux jets required to simulate astrophysical positron conditions have so far been absent. In the past few years, we performed extensive experiments generating positrons with intense lasers where we found that relativistic electron and positron jets are produced by irradiating a solid gold target with an intense picosecond laser pulse. The positron temperatures in directions parallel and transverse to the beam both exceeded 0.5 MeV, and the density of electrons and positrons in these jets are of order 1016 cm-3 and 1013 cm-3, respectively. With the increasing performance of high-energy ultra-short laser pulses, we expect that a high-density, up to 1018 cm-3, relativistic pair-plasma is achievable, a novel regime of laboratory-produced hot dense matter.

  3. Investigation of the optical characteristics of a laser-produced plasma cloud expanding into a background gas

    SciTech Connect

    Annenkov, A I; Bessarab, A V; Galakhov, I V; Garanin, Sergey G; Gusakov, A V; Zhidkov, N V; Zhmailo, V A; Izgorodin, V M; Kovalenko, V P; Krotov, V A; Mis'ko, V V; Novikova, E A; Starodubtsev, V A; Starodubtsev, K V; Statsenko, V P; Sungatullin, R R; Tachaev, G V; Sheremet'ev, Yu N

    2010-12-09

    An investigation is made of the dynamics and visible-range luminosity of the plasma cloud produced behind the front of a shock wave in air at a pressure of 1 Torr. The shock wave was produced on introducing the radiation of the twelve-channel Iskra-5 laser facility with a total energy of {approx}2300 J into a hollow spherical plastic target of mass {approx}10{sup -4} g. Experimental data are compared with simulations. (laser plasma)

  4. Cavitations induced by plasmas, plasmas induced by cavitations, and plasmas produced in cavitations

    NASA Astrophysics Data System (ADS)

    Sasaki, Koichi

    2015-11-01

    Cavitation bubbles are not static bubbles but have dynamics of expansion, shrinkage, and collapse. Since the collapse of a cavitation bubble is roughly an adiabatic process, the inside of the bubble at the collapse has a high temperature and a high pressure, resulting in the production of a plasma. This talk will be focused on cavitation-related plasma phenomena and the role of the cavitation bubble in the synthesis of nanoparticles. A method for inducing a cavitation bubble is laser ablation in liquid. After the disappearance of laser-produced plasma with optical emission, we have observed the formation of a cavitation bubble. We have found that the inside of the cavitation bubble is the reaction field for the synthesis of nanoparticles. The atomic and molecular species ejected from the ablation target toward the liquid are transported into the cavitation bubble, and they condense into nanoparticles inside it. It is important to note that nanoparticles are stored inside the cavitation bubble until its collapse. We have shown that the size and the structure of nanoparticles are controlled by controlling the dynamics of the cavitation bubbles. Another method for inducing cavitation bubbles is to use ultrasonic power. We have found a simple method for the efficient production of standing cavitation bubbles. The method is just inserting a punching metal plate into water irradiated by ultrasonic wave. The depth of water and the position of the punching plate should be tuned precisely. We have proposed the mechanism of the efficient production of cavitation bubbles by this method. Currently, we try to have electric discharges in cavitation bubbles with the intention of realizing nonequilibrium sonochemistry. In particular, the electric discharge in a laser-induced cavitation bubble shows interesting distortion of the bubble shape, which suggests the electrostatic characteristics of the cavitation bubble.

  5. Producing nitric oxide by pulsed electrical discharge in air for portable inhalation therapy.

    PubMed

    Yu, Binglan; Muenster, Stefan; Blaesi, Aron H; Bloch, Donald B; Zapol, Warren M

    2015-07-01

    Inhalation of nitric oxide (NO) produces selective pulmonary vasodilation and is an effective therapy for treating pulmonary hypertension in adults and children. In the United States, the average cost of 5 days of inhaled NO for persistent pulmonary hypertension of the newborn is about $14,000. NO therapy involves gas cylinders and distribution, a complex delivery device, gas monitoring and calibration equipment, and a trained respiratory therapy staff. The objective of this study was to develop a lightweight, portable device to serve as a simple and economical method of producing pure NO from air for bedside or portable use. Two NO generators were designed and tested: an offline NO generator and an inline NO generator placed directly within the inspiratory line. Both generators use pulsed electrical discharges to produce therapeutic range NO (5 to 80 parts per million) at gas flow rates of 0.5 to 5 liters/min. NO was produced from air, as well as gas mixtures containing up to 90% O2 and 10% N2. Potentially toxic gases produced in the plasma, including nitrogen dioxide (NO2) and ozone (O3), were removed using a calcium hydroxide scavenger. An iridium spark electrode produced the lowest ratio of NO2/NO. In lambs with acute pulmonary hypertension, breathing electrically generated NO produced pulmonary vasodilation and reduced pulmonary arterial pressure and pulmonary vascular resistance index. In conclusion, electrical plasma NO generation produces therapeutic levels of NO from air. After scavenging to remove NO2 and O3 and filtration to remove particles, electrically produced NO can provide safe and effective treatment of pulmonary hypertension. PMID:26136478

  6. Producing nitric oxide by pulsed electrical discharge in air for portable inhalation therapy.

    PubMed

    Yu, Binglan; Muenster, Stefan; Blaesi, Aron H; Bloch, Donald B; Zapol, Warren M

    2015-07-01

    Inhalation of nitric oxide (NO) produces selective pulmonary vasodilation and is an effective therapy for treating pulmonary hypertension in adults and children. In the United States, the average cost of 5 days of inhaled NO for persistent pulmonary hypertension of the newborn is about $14,000. NO therapy involves gas cylinders and distribution, a complex delivery device, gas monitoring and calibration equipment, and a trained respiratory therapy staff. The objective of this study was to develop a lightweight, portable device to serve as a simple and economical method of producing pure NO from air for bedside or portable use. Two NO generators were designed and tested: an offline NO generator and an inline NO generator placed directly within the inspiratory line. Both generators use pulsed electrical discharges to produce therapeutic range NO (5 to 80 parts per million) at gas flow rates of 0.5 to 5 liters/min. NO was produced from air, as well as gas mixtures containing up to 90% O2 and 10% N2. Potentially toxic gases produced in the plasma, including nitrogen dioxide (NO2) and ozone (O3), were removed using a calcium hydroxide scavenger. An iridium spark electrode produced the lowest ratio of NO2/NO. In lambs with acute pulmonary hypertension, breathing electrically generated NO produced pulmonary vasodilation and reduced pulmonary arterial pressure and pulmonary vascular resistance index. In conclusion, electrical plasma NO generation produces therapeutic levels of NO from air. After scavenging to remove NO2 and O3 and filtration to remove particles, electrically produced NO can provide safe and effective treatment of pulmonary hypertension.

  7. Doppler spectroscopy on plasma discharges produced in Proto-MPEX

    NASA Astrophysics Data System (ADS)

    Dhaliwal, Runpal; Biewer, Theodore; Klepper, Chris; Martin, Elijah; Rapp, Juergen

    2015-11-01

    The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) is a linear machine that produces pulsed plasma discharges, and is intended to study plasma-material interactions in conditions similar to those found in future fusion reactors. A high-resolution McPherson Czerny-Turner visible range spectrometer has been installed to study the behavior of ions in the plasma. Together with a Princeton Instruments EMCCD camera and an external trigger box, this system provides excellent spectral and temporal resolution for viewing the emission spectra of the discharges. Around 100 lines of sight have been established for use by this and other diagnostics in the lab. Initial data from recent experiments validate the utility of this setup. Analysis of spectral lines in helium and deuterium plasmas yields valuable information regarding the temperature and density of plasma ions at various locations in the machine as the various RF heating sources are implemented. Differentiating the thermal width of lines from other sources of broadening is an ongoing process. In addition to He I lines, data indicates the presence of the He II line at 468.5 nm, which corresponds to emission from singly ionized atoms at higher temperatures.

  8. 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.

  9. Plume Dynamics of Laser-Produced Swine Muscle Tissue Plasma.

    PubMed

    Camacho, Joaquin J; Diaz, Luis; Marin-Roldan, Alicia; Moncayo, Samuel; Caceres, Jorge O

    2016-07-01

    We report on the plume dynamics of the plasma induced by laser ablation of a swine skeletal muscle tissue sample in different vacuum conditions. Pulses from a transversely excited atmospheric CO2 laser were focused onto a target sample and the induced plasma was allowed to expand in different air pressures. The expansion features were studied using fast photography of the overall visible emission by using a gated intensified charged coupled device. Free expansion and plume splitting were observed at different pressure levels. The expansion of the plasma plume front was analyzed using various expansion models and the velocity of the plume front was estimated. The effect of the number of accumulated laser shots on the crater volume at different ambient air pressures and an elemental analysis of the sample were performed using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (EDX) analysis. The surface morphology of the irradiated surface showed that increasing the pressure of the ambient gas decreased the ablated mass, or in other words it reduced significantly the laser-target coupling. PMID:27301327

  10. Electrostatic instabilities in circularly polarized microwave produced magnetized plasmas

    SciTech Connect

    Ghorbanalilu, M.; Shokri, B.

    2009-12-15

    The growth rate of electrostatic instabilities of electron oscillation and low-frequency (LF) ion oscillation are investigated for a plasma produced by a circularly polarized microwave field during the breakdown process. The plasma is magnetized by an external homogenous static magnetic field on the direction of microwave field propagation. Numerical calculations show that the electron and ion perturbations are unstable in such an anisotropic plasma. Electron perturbations have the maximum growth rate across the magnetic field. In addition, ion perturbation growth rate is minimum on this direction. The LF ion oscillation is excited by Cherenkov emission mechanism due to the nonequilibrium form of the electron velocity distribution function. Electron oscillation growth rate decreases by increasing the external magnetic field, while the LF ion oscillation increases smoothly and reaches a maximum when the electron oscillation is stopped.

  11. System to continuously produce carbon fiber via microwave assisted plasma processing

    DOEpatents

    White, Terry L [Knoxville, TN; Paulauskas, Felix L [Knoxville, TN; Bigelow, Timothy S [Knoxville, TN

    2010-11-02

    A system to continuously produce fully carbonized or graphitized carbon fibers using microwave-assisted plasma (MAP) processing comprises an elongated chamber in which a microwave plasma is excited in a selected gas atmosphere. Fiber is drawn continuously through the chamber, entering and exiting through openings designed to minimize in-leakage of air. There is a gradient of microwave power within the chamber with generally higher power near where the fiber exits and lower power near where the fiber enters. Polyacrylonitrile (PAN), pitch, or any other suitable organic/polymeric precursor fibers can be used as a feedstock for the inventive system. Oxidized or partially oxidized PAN or pitch or other polymeric fiber precursors are run continuously through a MAP reactor in an inert, non-oxidizing atmosphere to heat the fibers, drive off the unwanted elements such as oxygen, nitrogen, and hydrogen, and produce carbon or graphite fibers faster than conventionally produced carbon fibers.

  12. Scaling mechanisms of vapour/plasma shielding from laser-produced plasmas to magnetic fusion regimes

    NASA Astrophysics Data System (ADS)

    Sizyuk, Tatyana; Hassanein, Ahmed

    2014-02-01

    The plasma shielding effect is a well-known mechanism in laser-produced plasmas (LPPs) reducing laser photon transmission to the target and, as a result, significantly reducing target heating and erosion. The shielding effect is less pronounced at low laser intensities, when low evaporation rate together with vapour/plasma expansion processes prevent establishment of a dense plasma layer above the surface. Plasma shielding also loses its effectiveness at high laser intensities when the formed hot dense plasma plume causes extensive target erosion due to radiation fluxes back to the surface. The magnitude of emitted radiation fluxes from such a plasma is similar to or slightly higher than the laser photon flux in the low shielding regime. Thus, shielding efficiency in LPPs has a peak that depends on the laser beam parameters and the target material. A similar tendency is also expected in other plasma-operating devices such as tokamaks of magnetic fusion energy (MFE) reactors during transient plasma operation and disruptions on chamber walls when deposition of the high-energy transient plasma can cause severe erosion and damage to the plasma-facing and nearby components. A detailed analysis of these abnormal events and their consequences in future power reactors is limited in current tokamak reactors. Predictions for high-power future tokamaks are possible only through comprehensive, time-consuming and rigorous modelling. We developed scaling mechanisms, based on modelling of LPP devices with their typical temporal and spatial scales, to simulate tokamak abnormal operating regimes to study wall erosion, plasma shielding and radiation under MFE reactor conditions. We found an analogy in regimes and results of carbon and tungsten erosion of the divertor surface in ITER-like reactors with erosion due to laser irradiation. Such an approach will allow utilizing validated modelling combined with well-designed and well-diagnosed LPP experimental studies for predicting

  13. Analysis of processes in DC arc plasma torches for spraying that use air as plasma forming gas

    NASA Astrophysics Data System (ADS)

    Frolov, V.; Ivanov, D.; Toropchin, A.

    2014-11-01

    Developed in Saint Petersburg State Polytechnical University technological processes of air-plasma spraying of wear-resistant, regenerating, hardening and decorative coatings used in number of industrial areas are described. The article contains examples of applications of air plasma spraying of coatings as well as results of mathematical modelling of processes in air plasma torches for spraying.

  14. Entrainment and acceleration of ambient plasma in a magnetized, laser-produced plasma

    NASA Astrophysics Data System (ADS)

    Bonde, Jeffrey; Vincena, Stephen; Gekelman, Walter

    2015-11-01

    Collisionless momentum coupling of a high energy density plasma expansion to a magnetized, ambient plasma is studied with a laser produced plasma expanding at speeds comparable to the background Alfvén speed, vexp = 1 . 2 ×107 cm/s ~vA . These expansions form diamagnetic cavities in which the background field is fully expelled. A moving Rosenbluth sheath forms at the boundary carrying a charge layer electrostatic sheath and inductive electric field. The total field in the lab frame was derived from emissive probe and magnetic probe measurements in the azimuthally symmetric experiment. Particle orbit tracing of an initially cold, stationary plasma tracked the evolution of the distribution of particles in these fields. A laser-induced fluorescence (LIF) diagnostic captured the resultant flows in the ambient argon plasma. The bulk flow fields from the orbit solvers and LIF are compared and found to agree vorbit ~vLIF ~ 3 ×105 cm/s while the distributions are highly non-Maxwellian. The orientation and magnitude of the flows show that the electrostatic sheath of the rapidly expanding plasma mostly entrains a tenuous background plasma, accelerating ions against the expansion. Orbit solvers show the effect has a significant dependence an ambient ion mass. This experiment was conducted in the Large Plasma Device at the Basic Plasma Science Facility and funded by grants from the US Department of Energy and the National Science Foundation.

  15. Air Plasma Formation in MHD Slipstream Accelerator for Mercury Lightcraft

    SciTech Connect

    Myrabo, L.N.; Raizer, Y.P.; Surzhikov, S.

    2004-03-30

    This paper investigates the physics of air plasma formation at the entrance of the MHD slipstream accelerator for the 'tractor-beam' Mercury Lightcraft. Two scenarios are analyzed. The first addresses the needs of the minimum power airspike assuming that all the power required for air plasma formation must come from the remote laser beam. The second case considers the constant-focus airspike and assumes that the breakdown criteria is satisfied by an on-board auxiliary source (e.g., electric discharge, RF source, microwave source, or E-beam)

  16. Air Plasma Formation in MHD Slipstream Accelerator for Mercury Lightcraft

    NASA Astrophysics Data System (ADS)

    Myrabo, L. N.; Raizer, Y. P.; Surzhikov, S.

    2004-03-01

    This paper investigates the physics of air plasma formation at the entrance of the MHD slipstream accelerator for the `tractor-beam' Mercury Lightcraft. Two scenarios are analyzed. The first addresses the needs of the minimum power airspike assuming that all the power required for air plasma formation must come from the remote laser beam. The second case considers the constant-focus airspike and assumes that the breakdown criteria is satisfied by an on-board auxiliary source (e.g., electric discharge, RF source, microwave source, or E-beam).

  17. Using advanced oxidation treatment for biofilm inactivation by varying water vapor content in air plasma

    NASA Astrophysics Data System (ADS)

    Ryota, Suganuma; Koichi, Yasuoka

    2015-09-01

    Biofilms are caused by environmental degradation in food factories and medical facilities. The inactivation of biofilms involves making them react with chemicals including chlorine, hydrogen peroxide, and ozone, although inactivation using chemicals has a potential problem because of the hazardous properties of the residual substance and hydrogen peroxide, which have slow reaction velocity. We successfully performed an advanced oxidation process (AOP) using air plasma. Hydrogen peroxide and ozone, which were used for the formation of OH radicals in our experiment, were generated by varying the amount of water vapor supplied to the plasma. By varying the content of the water included in the air, the main product was changed from air plasma. When we increased the water content in the air, hydrogen peroxide was produced, while ozone peroxide was produced when we decreased the water content in the air. By varying the amount of water vapor, we realized a 99.9% reduction in the amount of bacteria in the biofilm when we discharged humidified air only. This work was supported by JSPS KAKENHI Grant Number 25630104.

  18. Volume Diffuse Dielectric Barrier Discharge Plasma Produced by Nanosecond High Voltage Pulse in Airflow

    NASA Astrophysics Data System (ADS)

    Qi, Haicheng; Gao, Wei; Fan, Zhihui; Liu, Yidi; Ren, Chunsheng

    2016-05-01

    Volume diffuse dielectric barrier discharge (DBD) plasma is produced in subsonic airflow by nanosecond high-voltage pulse power supply with a plate-to-plate discharge cell at 6 mm air gap length. The discharge images, optical emission spectra (OES), the applied voltage and current waveforms of the discharge at the changed airflow rates are obtained. When airflow rate is increased, the transition of the discharge mode and the variations of discharge intensity, breakdown characteristics and the temperature of the discharge plasma are investigated. The results show that the discharge becomes more diffuse, discharge intensity is decreased accompanied by the increased breakdown voltage and time lag, and the temperature of the discharge plasma reduces when airflow of small velocity is introduced into the discharge gap. These phenomena are because that the airflow changes the spatial distribution of the heat and the space charge in the discharge gap. supported by National Natural Science Foundation of China (No. 51437002)

  19. Amateur scientists - producing light from a bubble of air

    SciTech Connect

    Hiller, R.A.; Barber, B.P.

    1995-02-01

    A glowing bubble of air cannot be bought anywhere at any price. But with an oscilloscope, a moderately precise sound generator, a home stereo amplifier and about $100, readers can turn sound into light through a process called sonoluminescence. The apparatus is relatively simple. A glass spherical flask filled with water serves as the resonator - the cavity in which sound is created to trap and drive the bubble. Small speakers, called piezoelectric transducers, are cemented to the flask and powered by an audo generator and amplifier. Bubbles introduced into the water coalesce at the center of the flask and produce a dim light visible to the unaided eye in a darkened room.

  20. Acceleration of neutrals in a nanosecond laser produced nickel plasma

    SciTech Connect

    Smijesh, N.; Chandrasekharan, K.; Philip, Reji

    2014-12-15

    Time of flight dynamics of slow neutrals, fast neutrals, and ions from a nanosecond laser produced nickel (Ni) plasma are investigated. Species arrival times confirm the hypothesis that fast neutrals are formed by the recombination of fast ions with free electrons. Both neutrals and ions are found to accelerate for a short interval immediately after ablation, which is attributed to internal Coulomb forces which create electrostatic potentials resulting in the charged particle acceleration. This process is further enhanced by laser-plasma energy coupling. Emission from neutrals could be measured for longer axial distances in the plume compared to that of ions confirming that the ions recombine to form neutrals as they move away from the target surface.

  1. An investigation of an underwater steam plasma discharge as alternative to air plasmas for water purification

    NASA Astrophysics Data System (ADS)

    Gucker, Sarah N.; Foster, John E.; Garcia, Maria C.

    2015-10-01

    An underwater steam plasma discharge, in which water itself is the ionizing media, is investigated as a means to introduce advanced oxidation species into contaminated water for the purpose of water purification. The steam discharge avoids the acidification observed with air discharges and also avoids the need for a feed gas, simplifying the system. Steam discharge operation did not result in a pH changes in the processing of water or simulated wastewater, with the actual pH remaining roughly constant during processing. Simulated wastewater has been shown to continue to decompose significantly after steam treatment, suggesting the presence of long-lived plasma produced radicals. During steam discharge operation, nitrate production is limited, and nitrite production was found to be below the detection threshold of (roughly 0.2 mg L-1). The discharge was operated over a broad range of deposited power levels, ranging from approximately 30 W to 300 W. Hydrogen peroxide production was found to scale with increasing power. Additionally, the hydrogen peroxide production efficiency of the discharge was found to be higher than many of the rates reported in the literature to date.

  2. Generation of low-temperature air plasma for food processing

    NASA Astrophysics Data System (ADS)

    Stepanova, Olga; Demidova, Maria; Astafiev, Alexander; Pinchuk, Mikhail; Balkir, Pinar; Turantas, Fulya

    2015-11-01

    The project is aimed at developing a physical and technical foundation of generating plasma with low gas temperature at atmospheric pressure for food industry needs. As known, plasma has an antimicrobial effect on the numerous types of microorganisms, including those that cause food spoilage. In this work an original experimental setup has been developed for the treatment of different foods. It is based on initiating corona or dielectric-barrier discharge in a chamber filled with ambient air in combination with a certain helium admixture. The experimental setup provides various conditions of discharge generation (including discharge gap geometry, supply voltage, velocity of gas flow, content of helium admixture in air and working pressure) and allows for the measurement of the electrical discharge parameters. Some recommendations on choosing optimal conditions of discharge generation for experiments on plasma food processing are developed.

  3. Relative ion expansion velocity in laser-produced plasmas

    NASA Technical Reports Server (NTRS)

    Goldsmith, S.; Moreno, J. C.; Griem, H. R.; Cohen, Leonard; Richardson, M. C.

    1988-01-01

    The spectra of highly ionized titanium, Ti XIII through Ti XXI, and C VI Lyman lines were excited in laser-produced plasmas. The plasma was produced by uniformly irradiating spherical glass microballoons coated with thin layers of titanium and parylene. The 24-beam Omega laser system produced short, 0.6 ns, and high-intensity, 4 x 10 to the 14th W/sq cm, laser pulses at a wavelength of 351 nm. The measured wavelength for the 2p-3s Ti XIII resonance lines had an average shift of + 0.023 A relative to the C VI and Ti XX spectral lines. No shift was found between the C VI, Ti XIX, and Ti XX lines. The shift is attributed to a Doppler effect, resulting from a difference of (2.6 + or - 0.2) x 10 to the 7th cm/s in the expansion velocities of Ti XIX and Ti XX ions compared to Ti XIII ions.

  4. Surface-dependent inactivation of model microorganisms with shielded sliding plasma discharges and applied air flow.

    PubMed

    Edelblute, Chelsea M; Malik, Muhammad A; Heller, Loree C

    2015-06-01

    Cold atmospheric plasma inactivates bacteria through reactive species produced from the applied gas. The use of cold plasma clinically has gained recent interest, as the need for alternative or supplementary strategies are necessary for preventing multi-drug resistant infections. The purpose of this study was to evaluate the antibacterial efficacy of a novel shielded sliding discharge based cold plasma reactor operated by nanosecond voltage pulses in atmospheric air on both biotic and inanimate surfaces. Bacterial inactivation was determined by direct quantification of colony forming units. The plasma activated air (afterglow) was bactericidal against Escherichia coli and Staphylococcus epidermidis seeded on culture media, laminate, and linoleum vinyl. In general, E. coli was more susceptible to plasma exposure. A bacterial reduction was observed with the application of air alone on a laminate surface. Whole-cell real-time PCR revealed a decrease in the presence of E. coli genomic DNA on exposed samples. These findings suggest that plasma-induced bacterial inactivation is surface-dependent.

  5. Ion Flux Characterization of H2 and D2 Plasmas Produced by an ECR Plasma Source

    NASA Astrophysics Data System (ADS)

    Kaiser, Eric; Capece, Angela; Roszell, John; Skinner, Charles; Koel, Bruce

    2013-10-01

    The use of lithium-conditioned plasma facing components in tokamaks has been shown to improve plasma confinement through a reduction in hydrogen recycling. Surface science techniques are being applied to probe the interactions between lithiated PFC's and H/D plasmas. A TectraTM Gen 2 plasma source has been commissioned that utilizes electron cyclotron resonance to produce a plasma discharge inside a vacuum test chamber and can produce ion fluxes similar to those typically seen in tokamaks. This source will be utilized to study H/D uptake by lithium films on Mo substrates as a precursor to NSTX-U experiments. In this work we report on the characterization of this source as a first step in its use in surface analysis studies. The source is operated in H2 and D2 gases and the subsequent ion flux of the plasma is measured by a Faraday Cup. Ion flux measurements are presented in a range of gas pressures and grid voltages up to 2 kV. Science Undergraduate Laboratory Internship funded by Department of Energy.

  6. Observation and numerical analysis of plasma parameters in a capillary discharge-produced plasma channel waveguide

    SciTech Connect

    Terauchi, Hiromitsu; Bobrova, Nadezhda; Sasorov, Pavel; Kikuchi, Takashi; Sasaki, Toru; Higashiguchi, Takeshi; Yugami, Noboru; Kodama, Ryosuke

    2011-03-01

    We observed the parameters of the discharge-produced plasma in cylindrical capillary. Plasma parameters of the waveguide were investigated by use of both a Normarski laser interferometer and a hydrogen plasma line spectrum. A space-averaged maximum temperature of 3.3 eV with electron densities of the order of 10{sup 17} cm{sup -3} was observed at a discharge time of 150 ns and a maximum discharge current of 200 A. One-dimensional dissipative magnetohydrodynamic (MHD) code was used to analyze the discharge dynamics in the gas-filled capillary discharge waveguide for high-intensity laser pulses. Simulations were performed for the conditions of the experiment. We compared the temporal behavior of the electron temperature and the radial electron density profiles, measured in the experiment with the results of the numerical simulations. They occurred to be in a good agreement. An ultrashort, intense laser pulse was guided by use of this plasma channel.

  7. Effect of high-power laser divergence on the plasma structural parameters during multiple filamentation in air

    NASA Astrophysics Data System (ADS)

    Geints, Yu. E.; Zemlyanov, A. A.

    2016-06-01

    Multiple filamentation of an infrared high-power laser pulse in air is considered. Based on the numerical solution to the unidirectional pulse propagation equation, the effect of radiation external focusing on the spatial structure of the plasma area produced in the filamentation region is studied. We show that the number of generated plasma channels in the beam wake and the density of their spatial distribution over the filamentation region depend on the initial divergence of laser radiation. We found that in a specific range of beam focusing the number of produced plasma channels could be minimized due to the formation of a consolidated thick plasma bunch at the beam axis.

  8. Two-dimensional fluorescence spectroscopy of laser-produced plasmas.

    PubMed

    Harilal, S S; LaHaye, N L; Phillips, M C

    2016-08-01

    We use a two-dimensional laser-induced fluorescence spectroscopy technique to measure the coupled absorption and emission properties of atomic species in plasmas produced via laser ablation of a solid aluminum target at atmospheric pressure. Emission spectra from the Al I 394.4 nm and Al I 396.15 nm transitions are measured while a frequency-doubled, continuous wave (cw) Ti:sapphire laser is tuned across the Al I 396.15 nm transition. The resulting two-dimensional spectra show the energy coupling between the two transitions via increased emission intensity for both transitions during resonant absorption of the cw laser at one transition. Time-delayed, gated detection of the emission spectrum is used to isolate resonantly excited fluorescence emission from thermally excited emission from the plasma. In addition, the tunable cw laser measures the absorption spectrum of the Al transition with ultrahigh resolution after the plasma has cooled, resulting in narrower spectral linewidths than observed in emission spectra. Our results highlight that fluorescence spectroscopy employing cw laser re-excitation after pulsed laser ablation combines benefits of both traditional emission and absorption spectroscopic methods. PMID:27472615

  9. Saturation of Langmuir waves in laser-produced plasmas

    SciTech Connect

    Baker, K.L.

    1996-04-01

    This dissertation deals with the interaction of an intense laser with a plasma (a quasineutral collection of electrons and ions). During this interaction, the laser drives large-amplitude waves through a class of processes known as parametric instabilities. Several such instabilities drive one type of wave, the Langmuir wave, which involves oscillations of the electrons relative to the nearly-stationary ions. There are a number of mechanisms which limit the amplitude to which Langmuir waves grow. In this dissertation, these mechanisms are examined to identify qualitative features which might be observed in experiments and/or simulations. In addition, a number of experiments are proposed to specifically look for particular saturation mechanisms. In a plasma, a Langmuir wave can decay into an electromagnetic wave and an ion wave. This parametric instability is proposed as a source for electromagnetic emission near half of the incident laser frequency observed from laser-produced plasmas. This interpretation is shown to be consistent with existing experimental data and it is found that one of the previous mechanisms used to explain such emission is not. The scattering version of the electromagnetic decay instability is shown to provide an enhanced noise source of electromagnetic waves near the frequency of the incident laser.

  10. Laser produced plasma soft x-ray generation

    SciTech Connect

    Cerjan, C.; Rosen, M.D.

    1991-05-20

    The efficiency of soft x-ray production from laser-irradiated plasmas is simulated for two different spectral regions. These two regions, 14{Angstrom} {plus minus} 15% and 130{Angstrom} {plus minus} 1%, were chosen for proximity mask or point-projection technological applications. Relatively large conversion efficiencies were obtained from irradiation of a stainless steel target using the conditions suggested by recent Hampshire Instruments' experiments for proximity masking. Pulse-width and laser frequency parameter studies were performed for point-projection applications which suggest that the conversion applications which suggest that the conversion efficiency is sensitive to pulse-width but not to laser frequency. One of the critical components of any x-ray lithographic scheme is of course the x-ray laser source. There are two primary contenders for a reliable, efficient source currently: synchrotron radiation and spectral emission from laser produced plasma. The dominant issue for laser-plasma emission is the conversion efficiency -- output in the intended operating spectral region relative the required incident laser energy. Simulations are described in the following for both high and low energy spectral regions which have been suggested by either the proximity masking or point-projection technology.

  11. Non-equilibrium Air Plasma for Wound Bleeding Control

    NASA Astrophysics Data System (ADS)

    Kuo, Spencer P.; Chen, Cheng-Yen; Lin, Chuan-Shun; Chiang, Shu-Hsing

    A low temperature non-equilibrium air plasma spray is tested as a blood coagulator. Emission spectroscopy of the plasma effluent indicates that it carries abundant reactive atomic oxygen (RAO), which can activate erythrocyte - platelet interactions to enhance blood coagulation for plug formation. Tests of the device for wound bleeding control were performed on pigs. Four types of wounds, straight cut and cross cut in the ham area, a hole in an ear saphenous vein, and a cut to an ear artery, were examined. The results showed that this plasma spray could effectively stop the bleeding and reduced the bleeding time considerably. Post-Operative observation of straight cut and cross cut wound healing was carried out. It was found that the plasma treatment had a positive impact on wound healing, in particular, of the cross cut wound; its healing time was shortened by a half.

  12. Porous materials produced from incineration ash using thermal plasma technology.

    PubMed

    Yang, Sheng-Fu; Chiu, Wen-Tung; Wang, To-Mai; Chen, Ching-Ting; Tzeng, Chin-Ching

    2014-06-01

    This study presents a novel thermal plasma melting technique for neutralizing and recycling municipal solid waste incinerator (MSWI) ash residues. MSWI ash residues were converted into water-quenched vitrified slag using plasma vitrification, which is environmentally benign. Slag is adopted as a raw material in producing porous materials for architectural and decorative applications, eliminating the problem of its disposal. Porous materials are produced using water-quenched vitrified slag with Portland cement and foaming agent. The true density, bulk density, porosity and water absorption ratio of the foamed specimens are studied here by varying the size of the slag particles, the water-to-solid ratio, and the ratio of the weights of the core materials, including the water-quenched vitrified slag and cement. The thermal conductivity and flexural strength of porous panels are also determined. The experimental results show the bulk density and the porosity of the porous materials are 0.9-1.2 g cm(-3) and 50-60%, respectively, and the pore structure has a closed form. The thermal conductivity of the porous material is 0.1946 W m(-1) K(-1). Therefore, the slag composite materials are lightweight and thermal insulators having considerable potential for building applications.

  13. Miniature Distillation Column for Producing LOX From Air

    NASA Technical Reports Server (NTRS)

    Rozzi, Jay C.

    2006-01-01

    The figure shows components of a distillation column intended for use as part of a system that produces high-purity liquid oxygen (LOX) from air by distillation. (The column could be easily modified to produce high-purity liquid nitrogen.) Whereas typical industrial distillation columns for producing high-purity liquid oxygen and/or nitrogen are hundreds of feet tall, this distillation column is less than 3 ft (less than about 0.9 m) tall. This column was developed to trickle-charge a LOX-based emergency oxygen system (EOS) for a large commercial aircraft. A description of the industrial production of liquid oxygen and liquid nitrogen by distillation is prerequisite to a meaningful description of the present miniaturized distillation column. Typically, such industrial production takes place in a chemical processing plant in which large quantities of high-pressure air are expanded in a turboexpander to (1) recover a portion of the electrical power required to compress the air and (2) partially liquefy the air. The resulting two-phase flow of air is sent to the middle of a distillation column. The liquid phase is oxygen-rich, and its oxygen purity increases as it flows down the column. The vapor phase is nitrogen-rich and its nitrogen purity increases as it flows up the column. A heater or heat exchanger, commonly denoted a reboiler, is at the bottom of the column. The reboiler is so named because its role is to reboil some of the liquid oxygen collected at the bottom of the column to provide a flow of oxygen-rich vapor. As the oxygen-rich vapor flows up the column, it absorbs the nitrogen in the down-flowing liquid by mass transfer. Once the vapor leaves the lower portion of the column, it interacts with down-flowing nitrogen liquid that has been condensed in a heat exchanger, commonly denoted a condenser, at the top of the column. Liquid oxygen and liquid nitrogen products are obtained by draining some of the purified product at the bottom and top of the column

  14. Producing air-stable monolayers of phosphorene and their defect engineering

    PubMed Central

    Pei, Jiajie; Gai, Xin; Yang, Jiong; Wang, Xibin; Yu, Zongfu; Choi, Duk-Yong; Luther-Davies, Barry; Lu, Yuerui

    2016-01-01

    It has been a long-standing challenge to produce air-stable few- or monolayer samples of phosphorene because thin phosphorene films degrade rapidly in ambient conditions. Here we demonstrate a new highly controllable method for fabricating high quality, air-stable phosphorene films with a designated number of layers ranging from a few down to monolayer. Our approach involves the use of oxygen plasma dry etching to thin down thick-exfoliated phosphorene flakes, layer by layer with atomic precision. Moreover, in a stabilized phosphorene monolayer, we were able to precisely engineer defects for the first time, which led to efficient emission of photons at new frequencies in the near infrared at room temperature. In addition, we demonstrate the use of an electrostatic gate to tune the photon emission from the defects in a monolayer phosphorene. This could lead to new electronic and optoelectronic devices, such as electrically tunable, broadband near infrared lighting devices operating at room temperature. PMID:26794866

  15. Producing air-stable monolayers of phosphorene and their defect engineering

    NASA Astrophysics Data System (ADS)

    Pei, Jiajie; Gai, Xin; Yang, Jiong; Wang, Xibin; Yu, Zongfu; Choi, Duk-Yong; Luther-Davies, Barry; Lu, Yuerui

    2016-01-01

    It has been a long-standing challenge to produce air-stable few- or monolayer samples of phosphorene because thin phosphorene films degrade rapidly in ambient conditions. Here we demonstrate a new highly controllable method for fabricating high quality, air-stable phosphorene films with a designated number of layers ranging from a few down to monolayer. Our approach involves the use of oxygen plasma dry etching to thin down thick-exfoliated phosphorene flakes, layer by layer with atomic precision. Moreover, in a stabilized phosphorene monolayer, we were able to precisely engineer defects for the first time, which led to efficient emission of photons at new frequencies in the near infrared at room temperature. In addition, we demonstrate the use of an electrostatic gate to tune the photon emission from the defects in a monolayer phosphorene. This could lead to new electronic and optoelectronic devices, such as electrically tunable, broadband near infrared lighting devices operating at room temperature.

  16. Producing air-stable monolayers of phosphorene and their defect engineering.

    PubMed

    Pei, Jiajie; Gai, Xin; Yang, Jiong; Wang, Xibin; Yu, Zongfu; Choi, Duk-Yong; Luther-Davies, Barry; Lu, Yuerui

    2016-01-22

    It has been a long-standing challenge to produce air-stable few- or monolayer samples of phosphorene because thin phosphorene films degrade rapidly in ambient conditions. Here we demonstrate a new highly controllable method for fabricating high quality, air-stable phosphorene films with a designated number of layers ranging from a few down to monolayer. Our approach involves the use of oxygen plasma dry etching to thin down thick-exfoliated phosphorene flakes, layer by layer with atomic precision. Moreover, in a stabilized phosphorene monolayer, we were able to precisely engineer defects for the first time, which led to efficient emission of photons at new frequencies in the near infrared at room temperature. In addition, we demonstrate the use of an electrostatic gate to tune the photon emission from the defects in a monolayer phosphorene. This could lead to new electronic and optoelectronic devices, such as electrically tunable, broadband near infrared lighting devices operating at room temperature.

  17. Producing air-stable monolayers of phosphorene and their defect engineering.

    PubMed

    Pei, Jiajie; Gai, Xin; Yang, Jiong; Wang, Xibin; Yu, Zongfu; Choi, Duk-Yong; Luther-Davies, Barry; Lu, Yuerui

    2016-01-01

    It has been a long-standing challenge to produce air-stable few- or monolayer samples of phosphorene because thin phosphorene films degrade rapidly in ambient conditions. Here we demonstrate a new highly controllable method for fabricating high quality, air-stable phosphorene films with a designated number of layers ranging from a few down to monolayer. Our approach involves the use of oxygen plasma dry etching to thin down thick-exfoliated phosphorene flakes, layer by layer with atomic precision. Moreover, in a stabilized phosphorene monolayer, we were able to precisely engineer defects for the first time, which led to efficient emission of photons at new frequencies in the near infrared at room temperature. In addition, we demonstrate the use of an electrostatic gate to tune the photon emission from the defects in a monolayer phosphorene. This could lead to new electronic and optoelectronic devices, such as electrically tunable, broadband near infrared lighting devices operating at room temperature. PMID:26794866

  18. Inactivation of the biofilm by the air plasma containing water

    NASA Astrophysics Data System (ADS)

    Suganuma, Ryota; Yasuoka, Koichi; Yasuoka Takeuchi lab Team

    2014-10-01

    Biofilms are caused by environmental degradation in food factory and medical facilities. Inactivation of biofilm has the method of making it react to chemicals including chlorine, hydrogen peroxide, and ozone. Although inactivation by chemicals has the problem that hazardous property of a residual substance and hydrogen peroxide have slow reaction velocity. We achieved advanced oxidation process (AOP) with air plasma. Hydrogen peroxide and ozone, which were used for the formation of OH radicals in our experiment, were able to be generated selectively by adjusting the amount of water supplied to the plasma. We inactivated Pseudomonas aeruginosa biofilm in five minutes with OH radicals generated by using hydrogen peroxide and ozone.

  19. Cold atmospheric pressure air plasma jet for medical applications

    SciTech Connect

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

    2008-06-16

    By flowing atmospheric pressure air through a direct current powered microhollow cathode discharge, we were able to generate a 2 cm 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.

  20. 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.

  1. Cold air plasma to decontaminate inanimate surfaces of the hospital environment.

    PubMed

    Cahill, Orla J; Claro, Tânia; O'Connor, Niall; Cafolla, Anthony A; Stevens, Niall T; Daniels, Stephen; Humphreys, Hilary

    2014-03-01

    The hospital environment harbors bacteria that may cause health care-associated infections. Microorganisms, such as multiresistant bacteria, can spread around the patient's inanimate environment. Some recently introduced biodecontamination approaches in hospitals have significant limitations due to the toxic nature of the gases and the length of time required for aeration. This study evaluated the in vitro use of cold air plasma as an efficient alternative to traditional methods of biodecontamination of hospital surfaces. Cultures of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli, and Acinetobacter baumannii were applied to different materials similar to those found in the hospital environment. Artificially contaminated sections of marmoleum, mattress, polypropylene, powder-coated mild steel, and stainless steel were then exposed to a cold air pressure plasma single jet for 30 s, 60 s, and 90 s, operating at approximately 25 W and 12 liters/min flow rate. Direct plasma exposure successfully reduced the bacterial load by log 3 for MRSA, log 2.7 for VRE, log 2 for ESBL-producing E. coli, and log 1.7 for A. baumannii. The present report confirms the efficient antibacterial activity of a cold air plasma single-jet plume on nosocomial bacterially contaminated surfaces over a short period of time and highlights its potential for routine biodecontamination in the clinical environment.

  2. Cold Air Plasma To Decontaminate Inanimate Surfaces of the Hospital Environment

    PubMed Central

    Claro, Tânia; O'Connor, Niall; Cafolla, Anthony A.; Stevens, Niall T.; Daniels, Stephen; Humphreys, Hilary

    2014-01-01

    The hospital environment harbors bacteria that may cause health care-associated infections. Microorganisms, such as multiresistant bacteria, can spread around the patient's inanimate environment. Some recently introduced biodecontamination approaches in hospitals have significant limitations due to the toxic nature of the gases and the length of time required for aeration. This study evaluated the in vitro use of cold air plasma as an efficient alternative to traditional methods of biodecontamination of hospital surfaces. Cultures of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli, and Acinetobacter baumannii were applied to different materials similar to those found in the hospital environment. Artificially contaminated sections of marmoleum, mattress, polypropylene, powder-coated mild steel, and stainless steel were then exposed to a cold air pressure plasma single jet for 30 s, 60 s, and 90 s, operating at approximately 25 W and 12 liters/min flow rate. Direct plasma exposure successfully reduced the bacterial load by log 3 for MRSA, log 2.7 for VRE, log 2 for ESBL-producing E. coli, and log 1.7 for A. baumannii. The present report confirms the efficient antibacterial activity of a cold air plasma single-jet plume on nosocomial bacterially contaminated surfaces over a short period of time and highlights its potential for routine biodecontamination in the clinical environment. PMID:24441156

  3. Surface functionalization of macroporous polymeric materials by treatment with air low temperature plasma.

    PubMed

    Molina, R; Sole, I; Vílchez, A; Bertran, E; Solans, C; Esquena, J

    2013-04-01

    Polystyrene/divinylbenzene (PS-DVB) macroporous monoliths obtained using highly concentrated emulsions as templates show a superhydrophobic behaviour, restricting their potential technological applications, especially those related to adhesion and wetting. Air plasma treatments were carried out in order to modulate wetting properties, modifying the surface chemical composition of macroporous polystyrene/divinylbenzene materials. The superhydrophobic behaviour was rapidly suppressed by air plasma treatment, greatly reducing the water contact angle, from approximately 150 degrees to approximately 90 degrees, in only 10 seconds of treatment. The new surface chemical groups, promoted by plasma active species, were characterized by surface analysis techniques with different depth penetration specificity (contact angle, XPS, FTIR and SEM). Results demonstrated that very short treatment times produced different chemical functionalities, mainly C-O, C=O, O-C=O and C-N, which provide the materials with predominantly acidic surface properties. However, plasma active species did not penetrate deeply through the interconnected pores of the material. FTIR analysis evidenced that the new hydrophilic surface groups promoted by plasma active species are in a negligibly concentration compared to bulk chemical groups, and are located in a very thin surface region on the PS-DVB monolith surface (significantly below 2 microm). XPS analysis of treated monoliths revealed a progressive increase of oxygen and nitrogen content as a function of plasma treatment time. However, oxidation of the PS-DVB monoliths surface prevails over the incorporation of nitrogen atoms. Finally, SEM studies indicated that the morphology of the plasma treated PS-DVB does not significantly change even for the longest air plasma treatment time studied (120 s).

  4. Plasma Parameter of a Capillary Discharge-Produced Plasma Channel to Guide an Ultrashort Laser Pulse

    SciTech Connect

    Higashiguchi, Takeshi; Terauchi, Hiromitsu; Bai, Jin-xiang; Yugami, Noboru

    2009-01-22

    We have observed the optical guiding of a 100-fs laser pulse with the laser intensity in the range of 10{sup 16} W/cm{sup 2} using a 1.5-cm long capillary discharge-produced plasma channel for compact electron acceleration applications. The optical pulse propagation using the plasma channel is achieved with the electron densities of 10{sup 17}-10{sup 18} cm{sup -3} and the electron temperatures of 0.5-4 eV at a discharge time delay of around 150 ns and a discharge current of 500 A with a pulse duration of 100-150 ns. An energy spectrum of the accelerated electrons from a laser-plasma acceleration scheme showed a peak at 1.3 MeV with a maximum energy tail of 1.6 MeV.

  5. Plasma processes for producing silanes and derivatives thereof

    DOEpatents

    Laine, Richard M; Massey, Dean Richard; Peterson, Peter Young

    2014-03-25

    The invention is generally related to process for generating one or more molecules having the formula Si.sub.xH.sub.y, Si.sub.xD.sub.y, Si.sub.xH.sub.yD.sub.z, and mixtures thereof, where x,y and z are integers .gtoreq.1, H is hydrogen and D is deuterium, such as silane, comprising the steps of: providing a silicon containing material, wherein the silicon containing material includes at least 20 weight percent silicon atoms based on the total weight of the silicon containing material; generating a plasma capable of vaporizing a silicon atom, sputtering a silicon atom, or both using a plasma generating device; and contacting the plasma to the silicon containing material in a chamber having an atmosphere that includes at least about 0.5 mole percent hydrogen atoms and/or deuterium atoms based on the total moles of atoms in the atmosphere; so that a molecule having the formula Si.sub.xH.sub.y; (e.g., silane) is generated. The process preferably includes a step of removing one or more impurities from the Si.sub.xH.sub.y (e.g., the silane) to form a clean Si.sub.xH.sub.y, Si.sub.xD.sub.y, Si.sub.xH.sub.yD.sub.z (e.g., silane). The process may also include a step of reacting the Si.sub.xH.sub.y, Si.sub.xD.sub.y, Si.sub.xH.sub.yD.sub.z (e.g., the silane) to produce a high purity silicon containing material such as electronic grade metallic silicon, photovoltaic grade metallic silicon, or both.

  6. [Testing of medicinal products produced from pooled plasma].

    PubMed

    Unkelbach, U; Hunfeld, A; Breitner-Ruddock, S

    2014-10-01

    Medicinal products produced from human plasma fall under the administrative batch release procedure of the competent authority. In Germany, this has been carried out since 1995 by the Paul Ehrlich Institute (PEI), the responsible state control agency for blood products. Medicinal products released for the European and national market are tested for quality, efficacy and safety. Experimental testing of the final product and the starting materials, the plasma pools, as well as control of the production documentation guarantee a constantly high product safety. In the 28,000 batches tested since the beginning of the state controlled batch release testing of these blood products at the PEI, there has been no transmission of infectious viruses (HIV, HBV and HCV) to any patient. The batch release has made a contribution to the improvement of product quality. This procedure is still an important tool to ensure safety of blood products. The PEI is integrated in the batch release network of the European Directorate for the Quality of Medicines & Health Care (EDQM) in Strasbourg. Regulations and guidelines for official control authority batch release (OCABR) ensure harmonized procedures for mutual recognition of batch release on the European level. The EU certificates and German national certificates are requested and accepted in over 70 countries worldwide. Experimental testing in the EU and the requisite certificates have developed into a seal of quality for the world market. PMID:25213735

  7. Storage of ions from laser-produced plasmas

    NASA Technical Reports Server (NTRS)

    Knight, R. D.

    1981-01-01

    A method of storing large numbers of metal ions created in laser-produced plasmas is presented. The outer electrode of the electrostatic ion trap is designed to give a harmonic axial potential. The ions trapped by the technique included Be(+), C(+), Al(+), Fe(+), and Pb(+). The initial number of ions stored (2 x 10 to the 8th) appeared to be the trap maximum since increasing the laser power beyond 2-3 MW did not change the ion number. An initial rapid decay in the 30-50 msec range was generally followed by a long tail at the 10% level with times greater than 100 msec. The technique should be valuable for refractory elements which cannot be easily vaporized for electron impact ionization.

  8. Laser electron acceleration in the prepulse produced plasma corona

    NASA Astrophysics Data System (ADS)

    Andreev, N. E.; Povarnitsyn, M. E.; Pugachev, L. P.; Levashov, P. R.

    2015-11-01

    The generation of hot electrons at grazing incidence of a subpicosecond relativistic-intense laser pulse onto the plane solid target is analyzed for the parameters of the petawatt class laser systems. We study the preplasma formation on the surface of solid Al target produced by the laser prepulses with different time structure. For modeling of the preplasma dynamics we use a wide-range two-temperature hydrodynamic model. As a result of simulations, the preplasma expansion under the action of the laser prepulse and the plasma density profiles for different contrast ratios of the nanosecond pedestal are found. These density profiles were used as the initial density distributions in 3-D PIC simulations of electron acceleration by the main P-polarized laser pulse. Results of modeling demonstrate the substantial increase of the characteristic energy and number of accelerated electrons for the grazing incidence of a subpicosecond intense laser pulse in comparison with the laser-target interaction at normal incidence.

  9. Indoor air cleaning using a pulsed discharge plasma

    SciTech Connect

    Mizuno, Akira; Kisanuki, Yoshiyuki; Noguchi, Masanobu; Katsura, Shinji; Lee, S.H.; Hong, Y.K.; Shin, S.Y.; Kang, J.H.

    1999-12-01

    The purpose of this paper is to develop a high-efficiency air-cleaning system for air pollutants such as tobacco smoke found in indoor environments. The authors investigated the basic characteristics of treating particulate matter and acetaldehyde (CH{sub 3}CHO) in a one-pass test using a pulse generator and a plasma-driven catalyst reactor, both of which are attachable to an air conditioner. Using a circulation test, the decrease in acetaldehyde concentration was measured in a closed vessel where the reactor had been placed. The removal efficiencies of particulate matter and acetaldehyde in the one-pass test (residence time of 10 ms) were 70% and 27%, respectively. In the circulation test, 98% of the suspended particles were collected after 2 min of operation and the acetaldehyde concentration decreased by 70% after 50 mins. It is believed that the TiO{sub 2} catalyst is excited by plasma-induced high-energy particles (electrons, photons, and metastable molecules), resulting in an enhanced pollutant removal. These test results indicate that the combination of plasma with TiO{sub 2} is a potential alternative in treating the pollutants in environmental tobacco smoke.

  10. Atmospheric plasma inactivation of foodborne pathogens on fresh produce surfaces.

    PubMed

    Critzer, Faith J; Kelly-Wintenberg, Kimberly; South, Suzanne L; Golden, David A

    2007-10-01

    A study was conducted to determine the effect of one atmosphere uniform glow discharge plasma (OAUGDP) on inactivation of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on apples, cantaloupe, and lettuce, respectively. A five-strain mixture of cultured test organisms was washed, suspended in phosphate buffer, and spot inoculated onto produce (7 log CFU per sample). Samples were exposed inside a chamber affixed to the OAUGDP blower unit operated at a power of 9 kV and frequency of 6 kHz. This configuration allows the sample to be placed outside of the plasma generation unit while allowing airflow to carry the antimicrobial active species, including ozone and nitric oxide, onto the food sample. Cantaloupe and lettuce samples were exposed for 1, 3, and 5 min, while apple samples were exposed for 30 s, 1 min, and 2 min. After exposure, samples were pummeled in 0.1% peptone water-2% Tween 80, diluted, and plated in duplicate onto selective media and tryptic soy agar and incubated as follows: E. coli O157:H7 (modified eosin methylene blue) and Salmonella (xylose lysine tergitol-4) for 48 h at 37 degrees C, and L. monocytogenes (modified Oxford medium) at 48 h for 32 degrees C. E. coli O157:H7 populations were reduced by >1 log after 30-s and 1-min exposures and >2 log after a 2-min exposure. Salmonella populations were reduced by >2 log after 1 min. Three- and 5-min exposure times resulted in >3-log reduction. L. monocytogenes populations were reduced by 1 log after 1 min of exposure. Three- and 5-min exposure times resulted in >3- and >5-log reductions, respectively. This process has the capability of serving as a novel, nonthermal processing technology to be used for reducing microbial populations on produce surfaces. PMID:17969610

  11. Air spark-like plasma source for antimicrobial NOx generation

    NASA Astrophysics Data System (ADS)

    Pavlovich, M. J.; Ono, T.; Galleher, C.; Curtis, B.; Clark, D. S.; Machala, Z.; Graves, D. B.

    2014-12-01

    We demonstrate and analyse the generation of nitrogen oxides and their antimicrobial efficacy using atmospheric air spark-like plasmas. Spark-like discharges in air in a 1 L confined volume are shown to generate NOx at an initial rate of about 1.5  ×  1016 NOx molecules/J dissipated in the plasma. Such a discharge operating in this confined volume generates on the order of 6000 ppm NOx in 10 min. Around 90% of the NOx is in the form of NO2 after several minutes of operation in the confined volume, suggesting that NO2 is the dominant antimicrobial component. The strong antimicrobial action of the NOx mixture after several minutes of plasma operation is demonstrated by measuring rates of E. coli disinfection on surfaces and in water exposed to the NOx mixture. Some possible applications of plasma generation of NOx (perhaps followed by dissolution in water) include disinfection of surfaces, skin or wound antisepsis, and sterilization of medical instruments at or near room temperature.

  12. Probe measurements of the electron distribution function in an electron-beam-produced ytterbium plasma

    SciTech Connect

    Bobrova, A. A.; Dubinov, A. E.; Esin, M. I.; Zolotov, S. V.; Maksimov, A. N.; Selemir, V. D.; Sidorov, I. I.; Shubin, A. Yu.

    2011-01-15

    A nonequilibrium anisotropic plasma produced by an electron beam in the residual air with a low content of ytterbium vapor was investigated by the probe method. It is found that a minor (at a level of a few ppm) admixture of ytterbium to low-pressure air substantially modifies the electron energy distribution function (EEDF): the main peak corresponding to thermal electrons broadens, and new peaks appear. It is shown that the observed change in the EEDF is caused by the low ionization energy of ytterbium, due to which one beam electron can ionize several ytterbium atoms. The new peaks in the EEDF correspond to the final energies of a beam electron after each subsequent ionizing collision with ytterbium atoms.

  13. Plasma dynamics in a discharge produced by a pulsed dual frequency inductively coupled plasma source

    SciTech Connect

    Mishra, Anurag; Lee, Sehan; Yeom, Geun Y.

    2014-11-01

    Using a Langmuir probe, time resolved measurements of plasma parameters were carried out in a discharge produced by a pulsed dual frequency inductively coupled plasma source. The discharge was sustained in an argon gas environment at a pressure of 10 mTorr. The low frequency (P{sub 2} {sub MHz}) was pulsed at 1 kHz and a duty ratio of 50%, while high frequency (P{sub 13.56} {sub MHz}) was maintained in the CW mode. All measurements were carried out at the center of the discharge and 20 mm above the substrate. The results show that, at a particular condition (P{sub 2} {sub MHz} = 200 W and P{sub 13.56} {sub MHz }= 600 W), plasma density increases with time and stabilizes at up to ∼200 μs after the initiation of P{sub 2} {sub MHz} pulse at a plasma density of (2 × 10{sup 17} m{sup −3}) for the remaining duration of pulse “on.” This stabilization time for plasma density increases with increasing P{sub 2} {sub MHz} and becomes ∼300 μs when P{sub 2} {sub MHz} is 600 W; however, the growth rate of plasma density is almost independent of P{sub 2} {sub MHz}. Interestingly, the plasma density sharply increases as the pulse is switched off and reaches a peak value in ∼10 μs, then decreases for the remaining pulse “off-time.” This phenomenon is thought to be due to the sheath modulation during the transition from “pulse on” to “pulse off” and partly due to RF noise during the transition period. The magnitude of peak plasma density in off time increases with increasing P{sub 2} {sub MHz}. The plasma potential and electron temperature decrease as the pulse develops and shows similar behavior to that of the plasma density when the pulse is switched off.

  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. Focused excimer laser initiated, radio frequency sustained high pressure air plasmas

    SciTech Connect

    Giar, Ryan; Scharer, John

    2011-11-15

    Measurements and analysis of air breakdown processes and plasma production by focusing 193 nm, 300 mJ, 15 MW high power laser radiation inside a 6 cm diameter helical radio frequency (RF) coil are presented. Quantum resonant multi-photon ionization (REMPI) and collisional cascade laser ionization processes are exploited that have been shown to produce high-density (n{sub e} {approx} 7 x 10{sup 16}/cm{sup 3}) cylindrical seed plasmas at 760 Torr. Air breakdown in lower pressures (from 7-22 Torr), where REMPI is the dominant laser ionization process, is investigated using an UV 18 cm focal length lens, resulting in a laser flux of 5.5 GW/cm{sup 2} at the focal spot. The focused laser power absorption and associated shock wave produce seed plasmas for sustainment by the RF (5 kW incident power, 1.5 s) pulse. Measurements of the helical RF antenna load impedance in the inductive and capacitive coupling regimes are obtained by measuring the loaded antenna reflection coefficient. A 105 GHz interferometer is used to measure the plasma electron density and collision frequency. Spectroscopic measurements of the plasma and comparison with the SPECAIR code are made to determine translational, rotational, and vibrational neutral temperatures and the associated neutral gas temperature. From this and the associated measurement of the gas pressure the electron temperature is obtained. Experiments show that the laser-formed seed plasma allows RF sustainment at higher initial air pressures (up to 22 Torr) than that obtained via RF-only initiation (<18 Torr) by means of a 0.3 J UV laser pulse.

  16. Extended plasma channels created by UV laser in air and their application to control electric discharges

    NASA Astrophysics Data System (ADS)

    Zvorykin, V. D.; Ionin, A. A.; Levchenko, A. O.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, I. V.; Ustinovskii, N. N.; Shutov, A. V.

    2015-02-01

    Results are presented from a series of experimental and theoretical studies on creating weakly ionized extended plasma channels in atmospheric air by 248-nm UV laser radiation and their application to control long high-voltage discharges. The main mechanisms of air ionization by UV laser pulses with durations from 100 fs to 25 ns and intensities in the ranges of 3×1011-1.5×1013 and 3×106-3×1011 W/cm2, respectively, which are below the threshold for optical gas breakdown, as well as the main relaxation processes in plasma with a density of 109-1017 cm-3, are considered. It is shown that plasma channels in air can be efficiently created by amplitude-modulated UV pulses consisting of a train of subpicosecond pulses producing primary photoelectrons and a long UV pulse suppressing electron attachment and sustaining the density of free electrons in plasma. Different modes of the generation and amplification of trains of subterawatt subpicosecond pulses and amplitude-modulated UV pulses with an energy of several tens of joules were implemented on the GARPUN-MTW hybrid Ti:sapphire-KrF laser facility. The filamentation of such UV laser beams during their propagation in air over distances of up to 100 m and the parameters of the corresponding plasma channels were studied experimentally and theoretically. Laser initiation of high-voltage electric discharges and control of their trajectories by means of amplitude-modulated UV pulses, as well as the spatiotemporal structure of breakdowns in air gaps with length of up to 80 cm, were studied.

  17. Extended plasma channels created by UV laser in air and their application to control electric discharges

    SciTech Connect

    Zvorykin, V. D. Ionin, A. A.; Levchenko, A. O.; Seleznev, L. V.; Sinitsyn, D. V.; Smetanin, I. V.; Ustinovskii, N. N.; Shutov, A. V.

    2015-02-15

    Results are presented from a series of experimental and theoretical studies on creating weakly ionized extended plasma channels in atmospheric air by 248-nm UV laser radiation and their application to control long high-voltage discharges. The main mechanisms of air ionization by UV laser pulses with durations from 100 fs to 25 ns and intensities in the ranges of 3×10{sup 11}–1.5×10{sup 13} and 3×10{sup 6}–3×10{sup 11} W/cm{sup 2}, respectively, which are below the threshold for optical gas breakdown, as well as the main relaxation processes in plasma with a density of 10{sup 9}–10{sup 17} cm{sup −3}, are considered. It is shown that plasma channels in air can be efficiently created by amplitude-modulated UV pulses consisting of a train of subpicosecond pulses producing primary photoelectrons and a long UV pulse suppressing electron attachment and sustaining the density of free electrons in plasma. Different modes of the generation and amplification of trains of subterawatt subpicosecond pulses and amplitude-modulated UV pulses with an energy of several tens of joules were implemented on the GARPUN-MTW hybrid Ti:sapphire-KrF laser facility. The filamentation of such UV laser beams during their propagation in air over distances of up to 100 m and the parameters of the corresponding plasma channels were studied experimentally and theoretically. Laser initiation of high-voltage electric discharges and control of their trajectories by means of amplitude-modulated UV pulses, as well as the spatiotemporal structure of breakdowns in air gaps with length of up to 80 cm, were studied.

  18. Evaluation of Low-Pressure Cold Plasma for Disinfection of ISS Grown Produce and Metal Instruments

    NASA Technical Reports Server (NTRS)

    Hummerick, Mary E.; Hintze, Paul E.; Maloney, Philip R.; Spencer, Lashelle E.; Coutts, Janelle L.; Franco, Carolina

    2016-01-01

    Low pressure cold plasma, using breathing air as the plasma gas, has been shown to be effective at precision cleaning aerospace hardware at Kennedy Space Center.Both atmospheric and low pressure plasmas are relatively new technologies being investigated for disinfecting agricultural commodities and medical instruments.

  19. Laser produced plasma for efficient extreme ultraviolet light sources

    SciTech Connect

    Donnelly, Tony; Cummins, Thomas; O' Gorman, Colm; Li Bowen; Harte, Colm S.; O'Reilly, Fergal; Sokell, Emma; Dunne, Padraig; O'Sullivan, Gerry

    2012-05-25

    Extreme ultraviolet emission from laser produced plasma and their relevance to EUV source development is discussed. The current state of the field for Sn LPP sources operating at 13.5 nm is described and initial results are given for EUV emission from CO{sub 2} laser irradiation of a bulk Sn target. A maximum conversion efficiency of 1.7% has been measured and the influence of the CO{sub 2} laser temporal profile on the CE is discussed. A double pulse irradiation scheme is shown to increase CE up to a maximum value of 2.1% for an optimum prepulse - pulse delay of 150 ns. The emergence of a new EUVL source wavelength at 6.7 nm based on Gd and Tb LPPs has been outlined. An initial experiment investigating picosecond laser irradiation as a means to produce strong 6.7 nm emission from a Gd{sub 2}O{sub 3} target has been performed and verified.

  20. A handheld low temperature atmospheric pressure air plasma gun for nanomaterial synthesis in liquid phase

    NASA Astrophysics Data System (ADS)

    Yu, Shuang; Wang, Kaile; Zuo, Shasha; Liu, Jiahui; Zhang, Jue; Fang, Jing

    2015-10-01

    A handheld low temperature atmospheric pressure air plasma gun based on a dielectric barrier structure with hollow electrodes was proposed. The portable plasma gun with an embedded mini air pump was driven by a 12 V direct voltage battery. The air plasma jet generated from the gun could be touched without a common shock hazard. Besides working in air, the plasma gun can also work in water. The diagnostic result of optical emission spectroscopy showed the difference in reactive species of air plasma jet between in air and in water. The plasma gun was excited in 20 ml chloroauric acid aqueous solution with a concentration of 1.214 mM. A significant amount of gold nanoparticles were synthesized after 2 min continuous discharge. The plasma gun with these unique features is applicable in plasma medicine, etching, and s-nthesis of nanomaterials.

  1. A handheld low temperature atmospheric pressure air plasma gun for nanomaterial synthesis in liquid phase

    SciTech Connect

    Yu, Shuang; Wang, Kaile; Zuo, Shasha; Liu, Jiahui; Zhang, Jue Fang, Jing

    2015-10-15

    A handheld low temperature atmospheric pressure air plasma gun based on a dielectric barrier structure with hollow electrodes was proposed. The portable plasma gun with an embedded mini air pump was driven by a 12 V direct voltage battery. The air plasma jet generated from the gun could be touched without a common shock hazard. Besides working in air, the plasma gun can also work in water. The diagnostic result of optical emission spectroscopy showed the difference in reactive species of air plasma jet between in air and in water. The plasma gun was excited in 20 ml chloroauric acid aqueous solution with a concentration of 1.214 mM. A significant amount of gold nanoparticles were synthesized after 2 min continuous discharge. The plasma gun with these unique features is applicable in plasma medicine, etching, and s-nthesis of nanomaterials.

  2. The Influence of spot size on the expansion dynamics of nanosecond-laser-produced copper plasmas in atmosphere

    SciTech Connect

    Li, Xingwen; Wei, Wenfu; Wu, Jian; Jia, Shenli; Qiu, Aici

    2013-06-28

    Laser produced copper plasmas of different spot sizes in air were investigated using fast photography and optical emission spectroscopy (OES). The laser energy was 33 mJ. There were dramatic changes in the plasma plume expansion into the ambient air when spot sizes changed from {approx}0.1 mm to {approx}0.6 mm. A stream-like structure and a hemispherical structure were, respectively, observed. It appeared that the same spot size resulted in similar expansion dynamics no matter whether the target was located in the front of or behind the focal point, although laser-induced air breakdown sometimes occurred in the latter case. Plasma plume front positions agree well with the classic blast wave model for the large spot-size cases, while an unexpected stagnation of {approx}80 ns occurred after the laser pulse ends for the small spot size cases. This stagnation can be understood in terms of the evolution of enhanced plasma shielding effects near the plasma front. Axial distributions of plasma components by OES revealed a good confinement effect. Electron number densities were estimated and interpreted using the recorded Intensified Charge Coupled Device (ICCD) images.

  3. The Influence of spot size on the expansion dynamics of nanosecond-laser-produced copper plasmas in atmosphere

    NASA Astrophysics Data System (ADS)

    Li, Xingwen; Wei, Wenfu; Wu, Jian; Jia, Shenli; Qiu, Aici

    2013-06-01

    Laser produced copper plasmas of different spot sizes in air were investigated using fast photography and optical emission spectroscopy (OES). The laser energy was 33 mJ. There were dramatic changes in the plasma plume expansion into the ambient air when spot sizes changed from ˜0.1 mm to ˜0.6 mm. A stream-like structure and a hemispherical structure were, respectively, observed. It appeared that the same spot size resulted in similar expansion dynamics no matter whether the target was located in the front of or behind the focal point, although laser-induced air breakdown sometimes occurred in the latter case. Plasma plume front positions agree well with the classic blast wave model for the large spot-size cases, while an unexpected stagnation of ˜80 ns occurred after the laser pulse ends for the small spot size cases. This stagnation can be understood in terms of the evolution of enhanced plasma shielding effects near the plasma front. Axial distributions of plasma components by OES revealed a good confinement effect. Electron number densities were estimated and interpreted using the recorded Intensified Charge Coupled Device (ICCD) images.

  4. Visible spectral power emitted from a laser produced uranium plasma

    NASA Technical Reports Server (NTRS)

    Williams, M. D.; Jalufka, N. W.

    1975-01-01

    The development of plasma-core nuclear reactors for advanced terrestrial and space-power sources is researched. Experimental measurements of the intensity and the spectral distribution of radiation from a nonfissioning uranium plasma are reported.

  5. A study of long aerosol initiated laser induced air breakdown plasmas

    NASA Astrophysics Data System (ADS)

    Pechacek, R. E.; Raleigh, M.; Greig, J. R.; Murphy, D. P.; Camelio, F.

    1984-06-01

    Results from three separate experiments on aerosol initiated, laser induced, air breakdown are described. The purpose of these experiments was to determine the maximum length of air breakdown plasma that can be created with a given laser pulse. Two separate neodymium glass lasers were used; the first produced an output pulse of 30 J in 60 ns and the second produced 200 J in 4 ns. Both pulses were at the wavelength of 1.06 micron. Two of the experiments used the aerosol produced by burning black gunpowder in the atmosphere which gave a mean particle size of about 0.5 micron. The third experiment attempted to use ragweed pollen with a mean particle size of about 10 micron, but these particles could not be adequately dispersed and no useful results were obtained.

  6. Structure of an exploding laser-produced plasma

    SciTech Connect

    Collette, A.; Gekelman, W.

    2011-05-15

    Currents and instabilities associated with an expanding dense plasma embedded in a magnetized background plasma are investigated by direct volumetric probe measurements of the magnetic field and floating potential. A diamagnetic cavity is formed and found to collapse rapidly compared to the expected magnetic diffusion time. The three-dimensional current density within the expanding plasma includes currents along the background magnetic field, in addition to the diamagnetic current. Correlation measurements reveal that flutelike structures at the plasma surface translate with the expanding plasma across the magnetic field and extend into the current system that sustains the diamagnetic cavity, possibly contributing to its collapse.

  7. Microstructure of Suspension Plasma Spray and Air Plasma Spray Al2O3-ZrO2 Composite Coatings

    NASA Astrophysics Data System (ADS)

    Chen, Dianying; Jordan, Eric H.; Gell, Maurice

    2009-09-01

    Al2O3-ZrO2 coatings were deposited by the suspension plasma spray (SPS) molecularly mixed amorphous powder and the conventional air plasma spray (APS) Al2O3-ZrO2 crystalline powder. The amorphous powder was produced by heat treatment of molecularly mixed chemical solution precursors below their crystallization temperatures. Phase composition and microstructure of the as-synthesized and heat-treated SPS and APS coatings were characterized by XRD and SEM. XRD analysis shows that the as-sprayed SPS coating is composed of α-Al2O3 and tetragonal ZrO2 phases, while the as-sprayed APS coating consists of tetragonal ZrO2, α-Al2O3, and γ-Al2O3 phases. Microstructure characterization revealed that the Al2O3 and ZrO2 phase distribution in SPS coatings is much more homogeneous than that of APS coatings.

  8. Inactivation of a 25.5 µm Enterococcus faecalis biofilm by a room-temperature, battery-operated, handheld air plasma jet

    NASA Astrophysics Data System (ADS)

    Pei, X.; Lu, X.; Liu, J.; Liu, D.; Yang, Y.; Ostrikov, K.; Chu, Paul K.; Pan, Y.

    2012-04-01

    Effective biofilm inactivation using a handheld, mobile plasma jet powered by a 12 V dc battery and operated in open air without any external gas supply is reported. This cold, room-temperature plasma is produced in self-repetitive nanosecond discharges with current pulses of ˜100 ns duration, current peak amplitude of ˜6 mA and repetition rate of ˜20 kHz. It is shown that the reactive plasma species penetrate to the bottom layer of a 25.5 µm-thick Enterococcus faecalis biofilm and produce a strong bactericidal effect. This is the thickest reported biofilm inactivated using room-temperature air plasmas.

  9. 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.

  10. Soft x-ray spectral measurements for temperature determination of laser produced aluminum plasmas

    SciTech Connect

    Mitchell, K.B.; Abdallah, J. Jr.; Peek, J.M.

    1986-01-01

    Time and space resolved measurements were made on plasmas produced by the SPRITE laser focused on aluminum targets. The experimental spectra are compared to theory in order to determine a characteristic plasma temperature. 4 refs., 8 figs.

  11. Experimental characterization of ultraviolet radiation of air in a high enthalpy plasma torch facility

    NASA Astrophysics Data System (ADS)

    Casses, C. J.; Bertrand, P. J.; Jacobs, C. M.; Mac Donald, M. E.; Laux, Ch. O.

    2015-06-01

    During atmospheric reentry, a plasma is formed ahead of the surface of the vehicle and the excited particle present in the plasma produces radiative heating fluxes to the surface of the vehicle. A high-temperature air plasma torch operating at atmospheric pressure was used to experimentally reproduce atmospheric reentry conditions. A high-resolution and absolute intensity emission spectrum (full width at half maximum (FWHM) = 0.064 nm) was obtained from 200 to 450 nm and then compared with computational results provided by the SPECAIR code [1]. This paper discusses the comparison of the two spectra over this wavelength range in order to confirm the validity of the calculation and provide direction to improve the calculated spectrum.

  12. Parameters of atmospheric plasmas produced by electrosurgical devices

    NASA Astrophysics Data System (ADS)

    Keidar, Michael; Shashurin, Alexey; Canady, Jerome

    2013-10-01

    Electrosurgical systems are extensively utilized in general surgery, surgical oncology, plastic and reconstructive surgery etc. In this work we study plasma parameters created by electrosurgical system SS-200E/Argon 2 of US Medical Innovations. The maximal length of the discharge plasma column at which the discharge can be sustained was determined as function of discharge power and argon flow rate. Electrical parameters including discharge current and voltage were measured. Recently proposed Rayleigh microwave scattering method for temporally resolved density measurements of small-size atmospheric plasmas was utilized. Simultaneously, evolution of plasma column was observed using intensified charge-coupled device (ICCD) camera.

  13. Man-made vitreous fiber produced from incinerator ash using the thermal plasma technique and application as reinforcement in concrete.

    PubMed

    Yang, Sheng-Fu; Wang, To-Mai; Lee, Wen-Cheng; Sun, Kin-Seng; Tzeng, Chin-Ching

    2010-10-15

    This study proposes using thermal plasma technology to treat municipal solid waste incinerator ashes. A feasible fiberization method was developed and applied to produce man-made vitreous fiber (MMVF) from plasma vitrified slag. MMVF were obtained through directly blending the oxide melt stream with high velocity compressed air. The basic technological characteristics of MMVF, including morphology, diameter, shot content, length and chemical resistance, are described in this work. Laboratory experiments were conducted on the fiber-reinforced concrete. The effects of fibrous content on compressive strength and flexural strength are presented. The experimental results showed the proper additive of MMVF in concrete can enhance its mechanical properties. MMVF products produced from incinerator ashes treated with the thermal plasma technique have great potential for reinforcement in concrete.

  14. Surface modification of PE film by DBD plasma in air

    NASA Astrophysics Data System (ADS)

    Ren, C.-S.; Wang, K.; Nie, Q.-Y.; Wang, D.-Z.; Guo, S.-H.

    2008-12-01

    In this paper, surface modification of polyethylene (PE) films is studied by dielectric barrier discharge plasma treatment in air. The treated samples were examined by water contact angle measurement, calculation of surface free energy, Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The water contact angle changes from the original value of 93.2° to the minimum value of 53.3° and surface free energy increases from 27.3 to 51.89 J/m 2 after treatment time of 50 s. Both ATR and XPS show some oxidized species are introduced into the sample surface by the plasma treatment and that the change tendencies of the water contact angle and surface free energy with the treatment time are the same as that of the oxygen concentration on the treated sample surface. Cu films were deposited on the treated and untreated PE surfaces. The peel adhesive strength between the Cu film and the treated sample is 1.5 MPa, whereas the value is only 0.8 MPa between the Cu film and the untreated PE. SEM pictures show that the Cu film deposited on the plasma treated PE surface is smooth and the crystal grain is smaller, contrarily the Cu film on the untreated PE surface is rough and the crystal grain is larger.

  15. Time dependent atomic processes in discharge produced low Z plasma

    NASA Astrophysics Data System (ADS)

    Yuyama, M.; Sasaki, T.; Horioka, K.; Kawamura, T.

    2008-05-01

    The z-pinch simulation have been performed with magneto-hydro dynamics and atomic population kinetics codes. A factor associated with transient atomic processes was proposed. The atomic transient degrees of dopant lithium in hydrogen plasma were calculated with initial plasma densities of 1.0 × 1016 ~ 5.0 × 1017cm-3. The higher initial plasma density is, the lower is the transient degree generally. It is also found that the transient properties of the atomic processes are sensitive to ionization energy and electron temperature.

  16. Moisture resistant and anti-reflection optical coatings produced by plasma polymerization of organic compounds

    NASA Technical Reports Server (NTRS)

    Hollahan, J. R.; Wydeven, T.

    1975-01-01

    The need for protective coatings on critical optical surfaces, such as halide crystal windows or lenses used in spectroscopy, has long been recognized. It has been demonstrated that thin, one micron, organic coatings produced by polymerization of flourinated monomers in low temperature gas discharge (plasma) exhibit very high degrees of moisture resistence, e.g., hundreds of hours protection for cesium iodide vs. minutes before degradation sets in for untreated surfaces. The index of refraction of these coatings is intermediate between that of the halide substrate and air, a condition for anti-reflection, another desirable property of optical coatings. Thus, the organic coatings not only offer protection, but improved transmittance as well. The polymer coating is non-absorbing over the range 0.4 to 40 microns with an exception at 8.0 microns, the expected absorption for C-F bonds.

  17. Persistence of uranium emission in laser-produced plasmas

    SciTech Connect

    LaHaye, N. L.; Harilal, S. S. Diwakar, P. K.; Hassanein, A.

    2014-04-28

    Detection of uranium and other nuclear materials is of the utmost importance for nuclear safeguards and security. Optical emission spectroscopy of laser-ablated U plasmas has been presented as a stand-off, portable analytical method that can yield accurate qualitative and quantitative elemental analysis of a variety of samples. In this study, optimal laser ablation and ambient conditions are explored, as well as the spatio-temporal evolution of the plasma for spectral analysis of excited U species in a glass matrix. Various Ar pressures were explored to investigate the role that plasma collisional effects and confinement have on spectral line emission enhancement and persistence. The plasma-ambient gas interaction was also investigated using spatially resolved spectra and optical time-of-flight measurements. The results indicate that ambient conditions play a very important role in spectral emission intensity as well as the persistence of excited neutral U emission lines, influencing the appropriate spectral acquisition conditions.

  18. Effects of atmospheric air plasma treatment of graphite and carbon felt electrodes on the anodic current from Shewanella attached cells.

    PubMed

    Epifanio, Monica; Inguva, Saikumar; Kitching, Michael; Mosnier, Jean-Paul; Marsili, Enrico

    2015-12-01

    The attachment of electrochemically active microorganisms (EAM) on an electrode is determined by both the chemistry and topography of the electrode surface. Pre-treatment of the electrode surface by atmospheric air plasma introduces hydrophilic functional groups, thereby increasing cell attachment and electroactivity in short-term experiments. In this study, we use graphite and carbon felt electrodes to grow the model EAM Shewanella loihica PV-4 at oxidative potential (0.2 V vs. Ag/AgCl). Cell attachment and electroactivity are measured through electrodynamic methods. Atmospheric air plasma pre-treatment increases cell attachment and current output at graphite electrodes by 25%, while it improves the electroactivity of the carbon felt electrodes by 450%. Air plasma pre-treatment decreased the coulombic efficiency on both carbon felt and graphite electrodes by 60% and 80%, respectively. Microbially produced flavins adsorb preferentially at the graphite electrode, and air plasma pre-treatment results in lower flavin adsorption at both graphite and carbon felt electrodes. Results show that air plasma pre-treatment is a feasible option to increase current output in bioelectrochemical systems.

  19. Surface treatment of polypropylene (PP) film by 50 Hz dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure

    SciTech Connect

    Joshi, Ujjwal Man Subedi, Deepak Prasad

    2015-07-31

    Thin films of polypropylene (PP) are treated for improving hydrophilicity using non-thermal plasma generated by 50 Hz line frequency dielectric barrier discharge produced in air and argon/air mixture at atmospheric pressure. PP samples before and after the treatments are studied using contact angle measurements, surface free energy calculations and scanning electron microscopy (SEM). Distilled water (H{sub 2}O), glycerol (C{sub 3}H{sub 8}O{sub 3}) and diiodomethane (CH{sub 2}I{sub 2}) are used as test liquids. The contact angle measurements between test liquids and PP samples are used to determine total surface free energy using sessile drop technique. PP films show a remarkable increase in surface free energy after plasma treatment. SEM analysis of the plasma-treated PP films shows that plasma treatment introduces greater roughness on the surface leading to the increased surface free energy. Furthermore, it is found that introducing a small quantity of argon can enhance the surface treatment remarkably.

  20. Laser plasma plume structure and dynamics in the ambient air: The early stage of expansion

    SciTech Connect

    Cirisan, M.; Jouvard, J. M.; Lavisse, L.; Hallo, L.; Oltra, R.

    2011-05-15

    Laser ablation plasma plume expanding into the ambient atmosphere may be an efficient way to produce nanoparticles. From that reason it would be interesting to study the properties of these laser induced plasmas formed under conditions that are known to be favorable for nanoparticles production. In general, plume behavior can be described as a two-stage process: a 'violent' plume expansion due to the absorption of the laser beam energy (during the laser pulse) followed by a fast adiabatic expansion in the ambient gas (after the end of the laser pulse). Plasma plume may last a few microseconds and may have densities 10{sup -6} times lower than the solid densities at temperatures close to the ambient temperature. Expansion of the plasma plume induced by the impact of a nanosecond laser beam ({lambda} 1064 nm) on the surface of metallic samples in the open air has been investigated by means of fast photography. Spatio-temporal evolution of the plume at the early stage of its expansion (first 330 ns) has been recorded. Structure and dynamics of the plasma plume have been investigated and compared to numerical simulations obtained with a hydro-code, as well as some scaling laws. In addition, measurements using different sample materials (Al, Fe, and Ti) have been performed in order to analyze the influence of target material on plume expansion.

  1. Contact-Free Inactivation of Candida albicans Biofilms by Cold Atmospheric Air Plasma

    PubMed Central

    Shimizu, Tetsuji; Isbary, Georg; Heinlin, Julia; Karrer, Sigrid; Klämpfl, Tobias G.; Li, Yang-Fang; Morfill, Gregor; Zimmermann, Julia L.

    2012-01-01

    Candida albicans is one of the main species able to form a biofilm on almost any surface, causing both skin and superficial mucosal infections. The worldwide increase in antifungal resistance has led to a decrease in the efficacy of standard therapies, prolonging treatment time and increasing health care costs. Therefore, the aim of this work was to demonstrate the applicability of atmospheric plasma at room temperature for inactivating C. albicans growing in biofilms without thermally damaging heat-sensitive materials. This so-called cold atmospheric plasma is produced by applying high voltage to accelerate electrons, which ionize the surrounding air, leading to the production of charged particles, reactive species, and photons. A newly developed plasma device was used, which exhibits a large plasma-generating surface area of 9 by 13 cm (117 cm2). Different time points were selected to achieve an optimum inactivation efficacy range of ≥3 log10 to 5 log10 reduction in CFU per milliliter, and the results were compared with those of 70% ethanol. The results obtained show that contact-free antifungal inactivation of Candida biofilms by cold atmospheric plasma is a promising tool for disinfection of surfaces (and items) in both health care settings and the food industry, where ethanol disinfection should be avoided. PMID:22467505

  2. Contact-free inactivation of Candida albicans biofilms by cold atmospheric air plasma.

    PubMed

    Maisch, Tim; Shimizu, Tetsuji; Isbary, Georg; Heinlin, Julia; Karrer, Sigrid; Klämpfl, Tobias G; Li, Yang-Fang; Morfill, Gregor; Zimmermann, Julia L

    2012-06-01

    Candida albicans is one of the main species able to form a biofilm on almost any surface, causing both skin and superficial mucosal infections. The worldwide increase in antifungal resistance has led to a decrease in the efficacy of standard therapies, prolonging treatment time and increasing health care costs. Therefore, the aim of this work was to demonstrate the applicability of atmospheric plasma at room temperature for inactivating C. albicans growing in biofilms without thermally damaging heat-sensitive materials. This so-called cold atmospheric plasma is produced by applying high voltage to accelerate electrons, which ionize the surrounding air, leading to the production of charged particles, reactive species, and photons. A newly developed plasma device was used, which exhibits a large plasma-generating surface area of 9 by 13 cm (117 cm(2)). Different time points were selected to achieve an optimum inactivation efficacy range of ≥3 log(10) to 5 log(10) reduction in CFU per milliliter, and the results were compared with those of 70% ethanol. The results obtained show that contact-free antifungal inactivation of Candida biofilms by cold atmospheric plasma is a promising tool for disinfection of surfaces (and items) in both health care settings and the food industry, where ethanol disinfection should be avoided.

  3. Influence of low atomic number plasma component on the formation of laser-produced plasma jets

    SciTech Connect

    Kasperczuk, A.; Pisarczyk, T.; Badziak, J.; Borodziuk, S.; Chodukowski, T.; Gus'kov, S. Yu.; Demchenko, N. N.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P.

    2010-11-15

    The results of investigations are presented that are connected with a very simple method of plasma jet formation, which consists in irradiating a massive planar target made of material with relatively high atomic number by a partly defocused laser beam. This brief communication is aimed at investigations of interaction of axially symmetrical light (plastic-CH) plasma with heavy (copper) plasma. It demonstrates that a relatively thin plastic plasma envelope can compress the Cu plasma and control the Cu-jet formation.

  4. Dependence of terahertz power from laser-produced plasma on laser intensity

    NASA Astrophysics Data System (ADS)

    Shin, J.-H.; Zhidkov, A.; Jin, Z.; Hosokai, T.; Kodama, R.

    2012-07-01

    Power of terahertz radiation from plasma which is generated from air irradiated by coupled (ω, 2ω) femtosecond laser pulses is analyzed for high laser intensities, for which non-linear plasma effects on the pulse propagation become essential, with multidimensional particle-in-cell simulations including the self-consistent plasma kinetics. The growth rate of THz power becomes slower as the laser intensity increases. A reason of such a lowering of efficiency in THz emission is found to be ionization of air by the laser pulse, which results in poor focusing of laser pulses.

  5. Generation of collisionless shock in laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Fiuza, Frederico

    2015-08-01

    Collisionless shocks are ubiquitous in astrophysical environments and are tightly connected with magnetic-field amplification and particle acceleration. The fast progress in high-power laser technology is bringing the study of high Mach number shocks into the realm of laboratory plasmas, where in situ measurements can be made helping us understand the fundamental kinetic processes behind shocks. I will discuss the recent progress in laser-driven shock experiments at state-of-the-art facilities like NIF and Omega and how these results, together with ab initio massively parallel simulations, can impact our understanding of magnetic field amplification and particle acceleration in astrophysical plasmas.

  6. Suprathermal electrons produced by beam-plasma-discharge

    NASA Technical Reports Server (NTRS)

    Sharp, W. E.

    1982-01-01

    Experiments conducted with a low energy plasma lens, HARP, in the electron beam of the large vacuum chamber at Johnson Space Center indicate that an enhanced population of 50 to 300 volt electrons appear when the beam goes into the Beam-Plasma Discharge (BPD) mode. Below the BPD instability the electron distribution appears to be characterized as non-energized single particle scattering and energy loss. At 100 cm from the beam core in the BPD mode the fluxes parallel to the beam are reduced by a factor of 20 with respect to the fluxes at 25 cm. Some evidence for isotropy near the beam core is presented.

  7. Plasma-activated air mediates plasmid DNA delivery in vivo

    PubMed Central

    Edelblute, Chelsea M; Heller, Loree C; Malik, Muhammad A; Bulysheva, Anna; Heller, Richard

    2016-01-01

    Plasma-activated air (PAA) provides a noncontact DNA transfer platform. In the current study, PAA was used for the delivery of plasmid DNA in a 3D human skin model, as well as in vivo. Delivery of plasmid DNA encoding luciferase to recellularized dermal constructs was enhanced, resulting in a fourfold increase in luciferase expression over 120 hours compared to injection only (P < 0.05). Delivery of plasmid DNA encoding green fluorescent protein (GFP) was confirmed in the epidermal layers of the construct. In vivo experiments were performed in BALB/c mice, with skin as the delivery target. PAA exposure significantly enhanced luciferase expression levels 460-fold in exposed sites compared to levels obtained from the injection of plasmid DNA alone (P < 0.001). Expression levels were enhanced when the plasma reactor was positioned more distant from the injection site. Delivery of plasmid DNA encoding GFP to mouse skin was confirmed by immunostaining, where a 3-minute exposure at a 10 mm distance displayed delivery distribution deep within the dermal layers compared to an exposure at 3 mm where GFP expression was localized within the epidermis. Our findings suggest PAA-mediated delivery warrants further exploration as an alternative approach for DNA transfer for skin targets. PMID:27110584

  8. Plasma-activated air mediates plasmid DNA delivery in vivo.

    PubMed

    Edelblute, Chelsea M; Heller, Loree C; Malik, Muhammad A; Bulysheva, Anna; Heller, Richard

    2016-01-01

    Plasma-activated air (PAA) provides a noncontact DNA transfer platform. In the current study, PAA was used for the delivery of plasmid DNA in a 3D human skin model, as well as in vivo. Delivery of plasmid DNA encoding luciferase to recellularized dermal constructs was enhanced, resulting in a fourfold increase in luciferase expression over 120 hours compared to injection only (P < 0.05). Delivery of plasmid DNA encoding green fluorescent protein (GFP) was confirmed in the epidermal layers of the construct. In vivo experiments were performed in BALB/c mice, with skin as the delivery target. PAA exposure significantly enhanced luciferase expression levels 460-fold in exposed sites compared to levels obtained from the injection of plasmid DNA alone (P < 0.001). Expression levels were enhanced when the plasma reactor was positioned more distant from the injection site. Delivery of plasmid DNA encoding GFP to mouse skin was confirmed by immunostaining, where a 3-minute exposure at a 10 mm distance displayed delivery distribution deep within the dermal layers compared to an exposure at 3 mm where GFP expression was localized within the epidermis. Our findings suggest PAA-mediated delivery warrants further exploration as an alternative approach for DNA transfer for skin targets. PMID:27110584

  9. 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.

  10. Spectroscopic Challenges in the Modelling and Diagnostics of High Temperature Air Plasma Radiation for Aerospace Applications

    SciTech Connect

    Laux, Christophe O.

    2007-04-06

    State-of-the-art spectroscopic models of the radiative transitions of interest for Earth re-entry and ground-based diagnostic facilities for aerospace applications are reviewed. The spectral range considered extends from the vacuum ultraviolet to the mid-infrared range (80 nm to 5.5 {mu}m). The modeling results are compared with absolute intensity measurements of the ultraviolet-visible-infrared emission of a well-characterized high-temperature air plasma produced with a 50 kW inductively coupled radio-frequency plasma torch, and with high-resolution absorption spectra from the Center for Astrophysics in the vacuum ultraviolet. The Spectroscopic data required to better model the spectral features of interest for aerospace applications are discussed.

  11. Ground level air convection produces frost damage patterns in turfgrass.

    PubMed

    Ackerson, Bruce J; Beier, Richard A; Martin, Dennis L

    2015-11-01

    Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass (Cynodon species Rich.), zoysiagrass (Zoysia species Willd.), and buffalograss [Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns. PMID:25796203

  12. Ground level air convection produces frost damage patterns in turfgrass.

    PubMed

    Ackerson, Bruce J; Beier, Richard A; Martin, Dennis L

    2015-11-01

    Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass (Cynodon species Rich.), zoysiagrass (Zoysia species Willd.), and buffalograss [Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns.

  13. Ground level air convection produces frost damage patterns in turfgrass

    NASA Astrophysics Data System (ADS)

    Ackerson, Bruce J.; Beier, Richard A.; Martin, Dennis L.

    2015-11-01

    Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass ( Cynodon species Rich.), zoysiagrass ( Zoysia species Willd.), and buffalograss [ Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns.

  14. Measurement of the impulse produced by a pulsed surface discharge actuator in air

    NASA Astrophysics Data System (ADS)

    Elias, P. Q.; Castera, P.

    2013-09-01

    The pulsed surface discharge in atmospheric pressure air generates a shock wave, thereby transferring an impulse to the surrounding gas. The aim of this work is to measure this impulse, using implementation of a plasma actuator based on linear surface discharges of length up to 10 cm, and of linear energy in a range 0.1-0.5 J cm-1. The shock wave generated by the discharge is visualized using a pulsed schlieren system and the impulse is measured with a dedicated balance. These measurements are correlated with 1D numerical simulations of pulsed energy depositions in a perfect gas. Experiments show that the discharge generates a cylindrical shock wave that travels at sonic speed after a few tens of microseconds, and produces an impulse that varies from 1 to 4 mN s m-1 and scales linearly with the linear energy density. This linearity agrees with the numerical simulations when 9.5% of the energy dissipated in the discharge is assumed to heat the gas. Overall, to produce a time-averaged force similar to the one achieved by dielectric barrier discharge (DBD) actuators, 2 to 3 times more power is required. However, surface discharge actuators do not saturate, and thus can induce time-averaged forces one or two orders of magnitude above DBD when pulsed at several hundreds of hertz.

  15. Common versus noble Bacillus subtilis differentially responds to air and argon gas plasma.

    PubMed

    Winter, Theresa; Bernhardt, Jörg; Winter, Jörn; Mäder, Ulrike; Schlüter, Rabea; Weltmann, Klaus-Dieter; Hecker, Michael; Kusch, Harald

    2013-09-01

    The applications of low-temperature plasma are not only confined to decontamination and sterilization but are also found in the medical field in terms of wound and skin treatment. For the improvement of already established and also for new plasma techniques, in-depth knowledge on the interactions between plasma and microorganism is essential. In an initial study, the interaction between growing Bacillus subtilis and argon plasma was investigated by using a growth chamber system suitable for low-temperature gas plasma treatment of bacteria in liquid medium. In this follow-up investigation, a second kind of plasma treatment-namely air plasma-was applied. With combined proteomic and transcriptomic analyses, we were able to investigate the plasma-specific stress response of B. subtilis toward not only argon but also air plasma. Besides an overlap of cellular responses due to both argon and air plasma treatment (DNA damage and oxidative stress), a variety of gas-dependent cellular responses such as growth retardation and morphological changes were observed. Only argon plasma treatments lead to a phosphate starvation response whereas air plasma induced the tryptophan operon implying damage by photooxidation. Biological findings were supported by the detection of reactive plasma species by optical emission spectroscopy and Fourier transformed infrared spectroscopy measurements.

  16. Common versus noble Bacillus subtilis differentially responds to air and argon gas plasma.

    PubMed

    Winter, Theresa; Bernhardt, Jörg; Winter, Jörn; Mäder, Ulrike; Schlüter, Rabea; Weltmann, Klaus-Dieter; Hecker, Michael; Kusch, Harald

    2013-09-01

    The applications of low-temperature plasma are not only confined to decontamination and sterilization but are also found in the medical field in terms of wound and skin treatment. For the improvement of already established and also for new plasma techniques, in-depth knowledge on the interactions between plasma and microorganism is essential. In an initial study, the interaction between growing Bacillus subtilis and argon plasma was investigated by using a growth chamber system suitable for low-temperature gas plasma treatment of bacteria in liquid medium. In this follow-up investigation, a second kind of plasma treatment-namely air plasma-was applied. With combined proteomic and transcriptomic analyses, we were able to investigate the plasma-specific stress response of B. subtilis toward not only argon but also air plasma. Besides an overlap of cellular responses due to both argon and air plasma treatment (DNA damage and oxidative stress), a variety of gas-dependent cellular responses such as growth retardation and morphological changes were observed. Only argon plasma treatments lead to a phosphate starvation response whereas air plasma induced the tryptophan operon implying damage by photooxidation. Biological findings were supported by the detection of reactive plasma species by optical emission spectroscopy and Fourier transformed infrared spectroscopy measurements. PMID:23794223

  17. Field demonstration and commercialization of silent discharge plasma hazardous air pollutant control technology

    SciTech Connect

    Rosocha, L.A.; Coogan, J.J.; Korzekwa, R.A.; Secker, D.A.; Reimers, R.F.; Herrmann, P.G.; Chase, P.J.; Gross, M.P. |; Jones, M.R.

    1996-07-01

    Silent electrical discharge plasma (dielectric barrier) reactors can decompose gas-phase pollutants by free-radical attack or electron-induced fragmentation. The radicals or electrons are produced by the large average volume nonthermal plasmas generated in the reactor. In the past decade, the barrier configuration has attracted attention for destroying toxic chemical agents for the military, removing harmful greenhouse gases, and treating other environmentally- hazardous chemical compounds. At the Los Alamos National Laboratory, we have been studying the silent discharge plasma (SDP) for processing gaseous-based hazardous chemicals for approximately five years. The key objective is to convert hazardous or toxic chemicals into non-hazardous compounds or into materials which are more easily managed. The main applications have been for treating off-gases from thermal treatment units, and for abating hazardous air-pollutant emissions (e.g., industrial air emissions, vapors extracted from contaminated soil or groundwater). In this paper, we will summarize the basic principles of SDP processing, discuss illustrative applications of the technology, and present results from small-scale field tests that are relevant to our commercialization effort.

  18. The effect of excitation wavelength on dynamics of laser-produced tin plasma

    SciTech Connect

    Harilal, S. S.; Sizyuk, T.; Hassanein, A.; Campos, D.; Sizyuk, V.; Hough, P.

    2011-03-15

    We investigated the effect of the excitation wavelength on the density evolution of laser-produced tin plasmas, both experimentally and numerically. For producing plasmas, Sn targets were excited with either 10.6 {mu}m CO{sub 2} laser or 1.06 {mu}m Nd:yttrium aluminum garnet laser; both are considered to be potential excitation lasers for extreme ultraviolet lithography laser-produced plasma light sources. The electron density of the plasma during the isothermal expansion regime was estimated using an interferometric technique. The Stark broadening of isolated singly-ionized emission was employed for deducing the density during the plasma adiabatic expansion regime. Our results indicate that the excitation source wavelength determines the initial density of the plasma, as well the plume expansion dynamics. Numerical simulation using HEIGHTS simulation package agrees well with the experimentally measured density profile.

  19. Morphology of ceramic particles produced by plasma-chemical synthesis

    NASA Astrophysics Data System (ADS)

    Arkhipov, V. A.; Bondarchuk, S. S.; Gol'din, V. D.; Zharova, I. K.; Zhukov, A. S.

    2015-11-01

    Thermal and diffusion processes in the droplet weakly concentrated metal salt solution during its heating in the plasma chemical reactor, in order to synthesize metal oxide powders are considered. Numerical study is based on previously proposed physical-mathematical model. The results of numerical calculations are analyzed to assess the possible influence of the operation parameters of the reactor and the characteristics of the initial solution (precursor) on the morphology of the particles formed.

  20. Topical applications of resonance internal conversion in laser produced plasma

    NASA Astrophysics Data System (ADS)

    Karpeshin, F. F.

    2007-04-01

    Physical aspects of resonance effects arising in plasma due to interactions of nuclei with the electrons are considered. Among them are resonance conversion (TEEN) and the reverse process of NEET. These processes are of great importance for pumping the excited nuclear states (isomers) and for accelerating their decay. Experiment is discussed on studying the unique 3.5-eV 229m Th nuclide.

  1. Astrophysical Weibel instability in counterstreaming laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Fox, William; Fiksel, Gennady; Bhattacharjee, Amitava; Change, Po-Yu; Germaschewski, Kai; Hu, Suxing; Nilson, Philip

    2014-06-01

    Astrophysical shock waves play diverse roles, including energizing cosmic rays in the blast waves of astrophysical explosions, and generating primordial magnetic fields during the formation of galaxies and clusters. These shocks are typically collisionless and require collective electromagnetic fields to couple the upstream and downstream plasmas. The Weibel instability has been proposed to provide the requisite interaction mechanism for shock formation in weakly-magnetized shocks by generating turbulent electric and magnetic fields in the shock front. This work presents the first laboratory identification of this Weibel instability between counterstreaming supersonic plasma flows and confirms its basic features, a significant step towards understanding these shocks. In the experiments, conducted on the OMEGA EP laser facility at the University of Rochester, a pair of plasmas plumes are generated by irradiating of a pair of opposing parallel plastic (CH) targets. The ion-ion interaction between the two plumes is collisionless, so as the plumes interpenetrate, supersonic, counterstreaming ion flow conditions are obtained. Electromagnetic fields formed in the interaction of the two plumes were probed with an ultrafast laser-driven proton beam, and we observed the growth of a highly striated, transverse instability with extended filaments parallel to the flows. The instability is identified as an ion-driven Weibel instability through agreement with analytic theory and particle-in-cell simulations, paving the way for further detailed laboratory study of this instability and its consequences for particle energization and shock formation.[1] W. Fox, G. Fiksel, A. Bhattacharjee, P. Y. Chang, K. Germaschewski, S. X. Hu, and P. M. Nilson, “Filamentation instability of counterstreaming laser-driven plasmas,” Phys. Rev. Lett. 111, 225002 (2013).

  2. Simulations of electromagnetic emissions produced in a thin plasma by a continuously injected electron beam

    NASA Astrophysics Data System (ADS)

    Annenkov, V. V.; Timofeev, I. V.; Volchok, E. P.

    2016-05-01

    In this paper, electromagnetic emissions produced in a thin beam-plasma system are studied using two-dimensional particle-in-cell simulations. For the first time, the problem of emission generation in such a system is considered in a realistic formulation allowing for the continuous injection of a relativistic electron beam through a plasma boundary. Specific attention is given to the thin plasma case in which the transverse plasma size is comparable to the typical wavelength of beam-driven oscillations. Such a case is often implemented in laboratory beam-plasma experiments and has a number of peculiarities. Emission from a thin plasma does not require intermediate generation of the electromagnetic plasma eigenmodes, as in an infinite case, and is more similar to the regular antenna radiation. In this work, we determine how efficiently the fundamental and the second harmonic emissions can be generated in previously modulated and initially homogeneous plasmas.

  3. Picosecond 14.7 nm interferometry of high intensity laser-produced plasmas

    SciTech Connect

    Dunn, J; Filevich, J; Smith, R F; Moon, S J; Rocca, J J; Keenan, R; Nilsen, J; Shlyaptsev, V N; Hunter, J R; Ng, A; Marconi, M C

    2004-10-14

    We have developed a compact, 14.7 nm, sub-5 ps x-ray laser source at LLNL together with a Mach-Zehnder type Diffraction Grating Interferometer built at Colorado State University for probing dense, high intensity laser-produced plasmas. The short wavelength and pulse length of the probe reduces refraction and absorption effects within the plasma and minimizes plasma motion blurring. This unique diagnostic capability gives precise 2-D density profile snapshots and is generating new data for rapidly evolving laser-heated plasmas. A review of the results from dense, mm-scale line focus plasma experiments will be described with detailed comparisons to hydrodynamic simulations.

  4. Heating and compression of a laser produced plasma in a pulsed magnetic field

    NASA Astrophysics Data System (ADS)

    Creel, J. R.; Donnelly, T.; Lunney, J. G.

    2016-08-01

    A pulsed 0.3 T magnetic field was used to heat and compress a low-temperature laser produced copper plasma. The magnetic field was generated using a planar 3-turn coil positioned 10 mm above the ablation spot. The plasma flowing through a central aperture in the coil was strongly focused. Inductive heating of the plasma caused a large enhancement of the overall visible light emission and the appearance of Cu II line emission. The plasma focusing is also evident in the constriction of the spatial distribution of deposited copper. The plasma heating and focusing can be explained in the framework of resistive magnetohydrodynamics.

  5. Feasibility of measuring density and temperature of laser produced plasmas using spectroscopic techniques.

    SciTech Connect

    Edens, Aaron D.

    2008-09-01

    A wide variety of experiments on the Z-Beamlet laser involve the creation of laser produced plasmas. Having a direct measurement of the density and temperature of these plasma would an extremely useful tool, as understanding how these quantities evolve in space and time gives insight into the causes of changes in other physical processes, such as x-ray generation and opacity. We propose to investigate the possibility of diagnosing the density and temperature of laser-produced plasma using temporally and spatially resolved spectroscopic techniques that are similar to ones that have been successfully fielded on other systems. Various researchers have measured the density and temperature of laboratory plasmas by looking at the width and intensity ratio of various characteristic lines in gases such as nitrogen and hydrogen, as well as in plasmas produced off of solid targets such as zinc. The plasma conditions produce two major measurable effects on the characteristic spectral lines of that plasma. The 1st is the Stark broadening of an individual line, which depends on the electron density of the plasma, with higher densities leading to broader lines. The second effect is a change in the ratio of various lines in the plasma corresponding to different ionization states. By looking at the ratio of these lines, we can gain some understanding of the plasma ionization state and consequently its temperature (and ion density when coupled with the broadening measurement). The hotter a plasma is, the higher greater the intensity of lines corresponding to higher ionization states. We would like to investigate fielding a system on the Z-Beamlet laser chamber to spectroscopically study laser produced plasmas from different material targets.

  6. Ejection of atoms by laser produced optical breakdown plasma

    SciTech Connect

    Wang, M.R.; Meng, H.C.

    1981-06-01

    High-power CO/sub 2/ laser radiation has been used to study the optical breakdown plasma on various solid targets (NaCl, KBr, ZnSe, and Ge). The breakdown threshold for irreversible changes of the optical characteristics was determined as well as the evaporation threshold of Na atoms from NaCl samples by CO/sub 2/ laser irradiation; the latter value was about 2.8 x 10/sup 7/ W/cm/sup 2/. The time profiles of the ejected Na atoms and the propagation of the atoms in front of the sample was measured with the laser fluorescence method.

  7. Properties of thermal air plasma with admixing of copper and carbon

    NASA Astrophysics Data System (ADS)

    Fesenko, S.; Veklich, A.; Boretskij, V.; Cressault, Y.; Gleizes, A.; Teulet, Ph

    2014-11-01

    This paper deals with investigations of air plasma with admixing of copper and carbon. Model plasma source unit with real breaking arc was used for the simulation of real discharges, which can be occurred during sliding of Cu-C composite electrodes on copper wire at electromotive vehicles. The complex technique of plasma property studies is developed. From one hand, the radial profiles of temperature and electron density in plasma of electric arc discharge in air between Cu-C composite and copper electrodes in air flow were measured by optical spectroscopy techniques. From another hand, the radial profiles of electric conductivity of plasma mixture were calculated by solution of energy balance equation. It was assumed that the thermal conductivity of air plasma is not depending on copper or carbon vapor admixtures. The electron density is obtained from electric conductivity profiles by calculation in assumption of local thermodynamic equilibrium in plasma. Computed in such way radial profiles of electron density in plasma of electric arc discharge in air between copper electrodes were compared with experimentally measured profiles. It is concluded that developed techniques of plasma diagnostics can be reasonably used in investigations of thermal plasma with copper and carbon vapors.

  8. Ion beam and plasma methods of producing diamondlike carbon films

    NASA Technical Reports Server (NTRS)

    Swec, Diane M.; Mirtich, Michael J.; Banks, Bruce A.

    1988-01-01

    A variety of plasma and ion beam techniques was employed to generate diamondlike carbon films. These methods included the use of RF sputtering, dc glow discharge, vacuum arc, plasma gun, ion beam sputtering, and both single and dual ion beam deposition. Since films were generated using a wide variety of techniques, the physico-chemical properties of these films varied considerably. In general, these films had characteristics that were desirable in a number of applications. For example, the films generated using both single and dual ion beam systems were evaluated for applications including power electronics as insulated gates and protective coatings on transmitting windows. These films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Nuclear reaction and combustion analysis indicated hydrogen to carbon ratios to be 1.00, which allowed the films to have good transmittance not only in the infrared, but also in the visible. Other evaluated properties of these films include band gap, resistivity, adherence, density, microhardness, and intrinsic stress. The results of these studies and those of the other techniques for depositing diamondlike carbon films are presented.

  9. Beam heated linear theta-pinch device for producing hot plasmas

    DOEpatents

    Bohachevsky, Ihor O.

    1981-01-01

    A device for producing hot plasmas comprising a single turn theta-pinch coil, a fast discharge capacitor bank connected to the coil, a fuel element disposed along the center axis of the coil, a predetermined gas disposed within the theta-pinch coil, and a high power photon, electron or ion beam generator concentrically aligned to the theta-pinch coil. Discharge of the capacitor bank generates a cylindrical plasma sheath within the theta-pinch coil which heats the outer layer of the fuel element to form a fuel element plasma layer. The beam deposits energy in either the cylindrical plasma sheath or the fuel element plasma layer to assist the implosion of the fuel element to produce a hot plasma.

  10. Treatment Characteristics of Polysaccharides and Endotoxin Using Oxygen Plasma Produced by RF Discharge

    NASA Astrophysics Data System (ADS)

    Kitazaki, Satoshi; Hayashi, Nobuya; Goto, Masaaki

    2010-10-01

    Treatment of polysaccharides and endotoxin were attempted using oxygen plasma produced by RF discharge. Oxygen radicals observed by optical light emission spectra are factors of decomposition of polysaccharides and endotoxin. Fourier transform infrared spectra indicate that most of chemical bonds in the polysaccharides are dissociated after irradiation of the oxygen plasma. Also, the decomposition rate of endotoxin was approximately 90% after irradiation of the oxygen plasma for 180 min.

  11. Treatment Characteristics of Polysaccharides and Endotoxin Using Oxygen Plasma Produced by RF Discharge

    SciTech Connect

    Kitazaki, Satoshi; Hayashi, Nobuya; Goto, Masaaki

    2010-10-13

    Treatment of polysaccharides and endotoxin were attempted using oxygen plasma produced by RF discharge. Oxygen radicals observed by optical light emission spectra are factors of decomposition of polysaccharides and endotoxin. Fourier transform infrared spectra indicate that most of chemical bonds in the polysaccharides are dissociated after irradiation of the oxygen plasma. Also, the decomposition rate of endotoxin was approximately 90% after irradiation of the oxygen plasma for 180 min.

  12. Bragg scattering of electromagnetic waves by microwave-produced plasma layers

    NASA Technical Reports Server (NTRS)

    Kuo, S. P.; Zhang, Y. S.

    1990-01-01

    A set of parallel plasma layers is generated by two intersecting microwave pulses in a chamber containing dry air at a pressure comparable to the upper atmosphere. The dependencies of breakdown conditions on the pressure and pulse length are examined. The results are shown to be consistent with the appearance of tail erosion of the microwave pulse caused by air breakdown. A Bragg scattering experiment, using the plasma layers as a Bragg reflector, is then performed. Both time domain and frequency domain measurements of wave scattering are conducted. The experimental results are found to agree very well with the theory.

  13. Laser-produced aluminum plasma expansion inside a plastic plasma envelope

    SciTech Connect

    Kasperczuk, A.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Parys, P.; Renner, O.; Rohlena, K.; Gus'kov, S. Yu.; Demchenko, N. N.; Ullschmied, J.; Krousky, E.; Pfeifer, M.; Skala, J.

    2012-09-15

    Previous experimental results demonstrated that the plasma pressure decreases with the growing atomic number of the target material. In this context, a question arose if the Al plasma outflow could be collimated using the plastic plasma as a compressor. To solve this problem, an experiment using a plastic target with an Al cylindrical insert was performed. The focal spot diameter substantially larger than that of the insert ensured simultaneous heating both target materials. This experiment proved that a production of Al plasma jets collimated by an action of outer plastic plasma is feasible [Kasperczuk et al., Laser Part. Beams 30, 1 (2012)]. The results of investigations presented here provide additional information on distributions of electron temperature in the outflowing plasma and time and space characteristics of ion emission, both registered at bare and constrained-flow Al targets. The experiment was carried out at the Prague asterix laser system iodine laser facility. The laser provided a 250 ps (full width at half maximum) pulse with the energy of 130 J at the third harmonic frequency ({lambda}{sub 3} = 0.438 {mu}m). A plastic target with an Al cylindrical insert of 400 {mu}m in diameter as well as a bare Al target (for comparison) was used. The focal spot diameter ({Phi}{sub L}) 1200 {mu}m ensured the lateral pressure effect of the plastic plasma strong enough to guarantee the effective Al plasma compression. The electron temperature measurements have shown that such Al plasma compression is accompanied by the increase of its temperature, dominance of which starts at distance of 0.5 mm from the target surface. Measurements of ion emission characteristics confirm the earlier numerical simulation prediction that in these conditions the plasma expansion geometry is closer to planar. The constrained Al plasma jet is very narrow and its axial velocity is considerably larger than the velocity of freely expanding Al plasma stream. It means that the plastic

  14. Non-thermal plasma for air and water remediation.

    PubMed

    Hashim, Siti Aiasah; Samsudin, Farah Nadia Dayana Binti; Wong, Chiow San; Abu Bakar, Khomsaton; Yap, Seong Ling; Mohd Zin, Mohd Faiz

    2016-09-01

    A modular typed dielectric barrier discharge (DBD) device is designed and tested for air and water remediation. The module is made of a number of DBD tubes that can be arranged in series or parallel. Each of the DBD tubes comprises inner electrode enclosed with dielectric barrier and arranged as such to provide a gap for the passage of gases. Non-thermal plasma generated in the gap effectively creates gaseous chemical reactions. Its efficacy in the remediation of gas stream containing high NOx, similar to diesel emission and wastewater containing latex, are presented. A six tubes DBD module has successfully removed more than 80% of nitric oxide from the gas stream. In another arrangement, oxygen was fed into a two tubes DBD to generate ozone for treatment of wastewater. Samples of wastewater were collected from a treatment pond of a rubber vulcanization pilot plant. The water pollution load was evaluated by the chemical oxygen demand (COD) and biological oxygen demand (BOD5) values. Preliminary results showed some improvement (about 13%) on the COD after treatment and at the same time had increased the BOD5 by 42%. This results in higher BOD5/COD ratio after ozonation which indicate better biodegradability of the wastewater.

  15. Non-thermal plasma for air and water remediation.

    PubMed

    Hashim, Siti Aiasah; Samsudin, Farah Nadia Dayana Binti; Wong, Chiow San; Abu Bakar, Khomsaton; Yap, Seong Ling; Mohd Zin, Mohd Faiz

    2016-09-01

    A modular typed dielectric barrier discharge (DBD) device is designed and tested for air and water remediation. The module is made of a number of DBD tubes that can be arranged in series or parallel. Each of the DBD tubes comprises inner electrode enclosed with dielectric barrier and arranged as such to provide a gap for the passage of gases. Non-thermal plasma generated in the gap effectively creates gaseous chemical reactions. Its efficacy in the remediation of gas stream containing high NOx, similar to diesel emission and wastewater containing latex, are presented. A six tubes DBD module has successfully removed more than 80% of nitric oxide from the gas stream. In another arrangement, oxygen was fed into a two tubes DBD to generate ozone for treatment of wastewater. Samples of wastewater were collected from a treatment pond of a rubber vulcanization pilot plant. The water pollution load was evaluated by the chemical oxygen demand (COD) and biological oxygen demand (BOD5) values. Preliminary results showed some improvement (about 13%) on the COD after treatment and at the same time had increased the BOD5 by 42%. This results in higher BOD5/COD ratio after ozonation which indicate better biodegradability of the wastewater. PMID:27056469

  16. Modification of polysulfone porous hollow fiber membranes by air plasma treatment

    NASA Astrophysics Data System (ADS)

    Volkov, V. V.; Ibragimov, R. G.; Abdullin, I. Sh; Gallyamov, R. T.; Ovcharova, A. A.; Bildyukevich, A. V.

    2016-09-01

    Air plasma treatment was used to enhance the surface hydrophilic properties of the polysulfone porous hollow fiber membranes prepared via a dry-wet phase invertion technique in the free spinning mode in air. Membranes prepared had porous asymmetric structure with macroporous support on the shell side and fine-porous selective layer on the lumen side. The wettability of the inner membrane surfaces were checked by contact angle measurements and FTIR was used to compare the surfaces before and after plasma treatment. Membrane morphology was examined with confocal scanning laser microscopy (CSLM). Contact angle measurements confirm that air plasma treatment affords improvement in the wettability of polysulfone membranes and FTIR results show that air plasmas chemically modify the lumen side membrane surface, however, there is no significant change in membranes chemical structure after modification. CSLM data obtained, as well as gas permeability (He and CO2) measurements show that after plasma treatment pore etching occurs.

  17. Air plasma processing of poly(methyl methacrylate) micro-beads: Surface characterisations

    NASA Astrophysics Data System (ADS)

    Liu, Chaozong; Cui, Nai-Yi; Osbeck, Susan; Liang, He

    2012-10-01

    This paper reports the surface processing of poly(methyl methacrylate) (PMMA) micro-beads by using a rotary air plasma reactor, and its effects on surface properties. The surface properties, including surface wettability, surface chemistry and textures of the PMMA beads, were characterised. It was observed that the air plasma processing can improve the surface wettability of the PMMA microbeads significantly. A 15 min plasma processing can reduce the surface water contact angle of PMMA beads to about 50° from its original value of 80.3°. This was accompanied by about 8% increase in surface oxygen concentration as confirmed by XPS analysis. The optical profilometry examination revealed the air plasma processing resulted in a rougher surface that has a “delicate” surface texture. It is concluded that the surface chemistry and texture, induced by air plasma processing, co-contributed to the surface wettability improvement of PMMA micro-beads.

  18. [The correction to spectroscopic diagnostics of plasma jet with air engulfment].

    PubMed

    Zhao, Wen-hua; Tang, Huang-zai; Tian, Kuo; Zhang, Guan-zhong

    2004-04-01

    A high-resolution, multi-line spectroscopic diagnostic system was used to detect two spectral line intensities in plasma jet simultaneously. The temperature profiles of an arc plasma jet issued into atmosphere and the concentrations of the air engulfment in the plasma jet were experimentally determined by means of the line absolute intensity method in this paper. The temperature profiles were obtained in two cases: the air engulfment in the plasma jet being considered and not being considered. The comparison of temperatures obtained in these two cases illustrates that the air engulfment in the plasma jet has considerable influence on spectroscopic diagnostic results. The neglect of the air engulfment brings on error in the temperature diagnostics with the absolute line intensity method. Especially in the region far away from the exit of the nozzle, the error is obvious.

  19. Thermodynamic and Transport Properties of Real Air Plasma in Wide Range of Temperature and Pressure

    NASA Astrophysics Data System (ADS)

    Wang, Chunlin; Wu, Yi; Chen, Zhexin; Yang, Fei; Feng, Ying; Rong, Mingzhe; Zhang, Hantian

    2016-07-01

    Air plasma has been widely applied in industrial manufacture. In this paper, both dry and humid air plasmas' thermodynamic and transport properties are calculated in temperature 300-100000 K and pressure 0.1-100 atm. To build a more precise model of real air plasma, over 70 species are considered for composition. Two different methods, the Gibbs free energy minimization method and the mass action law method, are used to determinate the composition of the air plasma in a different temperature range. For the transport coefficients, the simplified Chapman-Enskog method developed by Devoto has been applied using the most recent collision integrals. It is found that the presence of CO2 has almost no effect on the properties of air plasma. The influence of H2O can be ignored except in low pressure air plasma, in which the saturated vapor pressure is relatively high. The results will serve as credible inputs for computational simulation of air plasma. supported by the National Key Basic Research Program of China (973 Program)(No. 2015CB251002), National Natural Science Foundation of China (Nos. 51521065, 51577145), the Science and Technology Project Funds of the Grid State Corporation (SGTYHT/13-JS-177), the Fundamental Research Funds for the Central Universities, and State Grid Corporation Project (GY71-14-004)

  20. Effects of Atmospheric Air Plasma Irradiation on pH of Water

    NASA Astrophysics Data System (ADS)

    Sarinont, Thapanut; Koga, Kazunori; Kitazaki, Satoshi; Uchida, Giichirou; Hayashi, Nobuya; Shiratani, Masaharu

    We have studied the effects of atmospheric air plasma irradiation to water using a scalable dielectric barrier discharge device. Measurements of the pH of water treated by the plasmas have shown the pH decreases due to peroxide molecules generated by plasma irradiation and depends on material of water container. We also found this plasma treated water has little effect on the growth enhancement on Radish sprouts compare with plasma irradiation on dry seeds and the plasma irradiation can affect them through the water buffer of 0.2 mm in thickness.

  1. Emittance of positron beams produced in intense laser plasma interaction

    SciTech Connect

    Chen Hui; Hazi, A.; Link, A.; Anderson, S.; Gronberg, J.; Izumi, N.; Tommasini, R.; Wilks, S.; Sheppard, J. C.; Meyerhofer, D. D.; Baldis, H. A.; Marley, E.; Park, J.; Williams, G. J.; Fedosejev, R.; Kerr, S.

    2013-01-15

    The first measurement of the emittance of intense laser-produced positron beams has been made. The emittance values were derived through measurements of positron beam divergence and source size for different peak positron energies under various laser conditions. For one of these laser conditions, we used a one dimensional pepper-pot technique to refine the emittance value. The laser-produced positrons have a geometric emittance between 100 and 500 mm{center_dot}mrad, comparable to the positron sources used at existing accelerators. With 10{sup 10}-10{sup 12} positrons per bunch, this low emittance beam, which is quasi-monoenergetic in the energy range of 5-20 MeV, may be useful as an alternative positron source for future accelerators.

  2. Measurements of magnetic fields using the Zeeman effect in laser-produced plasmas

    SciTech Connect

    Briand, J.; Kieffer, J.C.; Gomes, A.; Arnas, C.; Dinguirard, J.P.; Quemener, Y.; Berge, L.; El Tamer, M.; Armengaud, M.

    1987-09-01

    In this article, experimental results on magnetic fields obtained from measurements of the Zeeman effect in laser-produced plasmas are presented. Observations of the coronal plasma produced by interaction between a carbon plane target and a 0.25 m laser beam, show for the first time at such short wavelengths the existence of toroidal and axial fields with amplitudes reaching, respectively, 0.35 and 0.5 MG.

  3. Geopolymers prepared from DC plasma treated air pollution control (APC) residues glass: properties and characterisation of the binder phase.

    PubMed

    Kourti, Ioanna; Devaraj, Amutha Rani; Bustos, Ana Guerrero; Deegan, David; Boccaccini, Aldo R; Cheeseman, Christopher R

    2011-11-30

    Air pollution control (APC) residues have been blended with glass-forming additives and treated using DC plasma technology to produce a high calcium aluminosilicate glass (APC glass). This has been used to form geopolymer-glass composites that exhibit high strength and density, low porosity, low water absorption, low leaching and high acid resistance. The composites have a microstructure consisting of un-reacted residual APC glass particles imbedded in a complex geopolymer and C-S-H gel binder phase, and behave as particle reinforced composites. The work demonstrates that materials prepared from DC plasma treated APC residues have potential to be used to form high quality pre-cast products.

  4. Injection of a coaxial-gun-produced magnetized plasma into a background helicon plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Lynn, Alan; Gilmore, Mark; Hsu, Scott

    2014-10-01

    A compact coaxial plasma gun is employed for experimental investigation of plasma bubble relaxation into a lower density background plasma. Experiments are being conducted in the linear device HelCat at UNM. The gun is powered by a 120-uF ignitron-switched capacitor bank, which is operated in a range of 5 to 10 kV and 100 kA. Multiple diagnostics are employed to investigate the plasma relaxation process. Magnetized argon plasma bubbles with velocities 1.2Cs, densities 1020 m-3 and electron temperature 13eV have been achieved. The background helicon plasma has density 1013 m-3, magnetic field from 200 to 500 Gauss and electron temperature 1eV. Several distinct operational regimes with qualitatively different dynamics are identified by fast CCD camera images. Additionally a B-dot probe array has been employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify plasma bubble configurations. Experimental data and analysis will be presented.

  5. Reinjection of transmitted laser light into laser-produced plasma for efficient laser ignition.

    PubMed

    Endo, Takuma; Takenaka, Yuhei; Sako, Yoshiyuki; Honda, Tomohisa; Johzaki, Tomoyuki; Namba, Shinichi

    2016-02-10

    For improving the laser absorption efficiency in laser ignition, the transmitted laser light was returned to the laser-produced plasma by using a corner cube. In the experiments, the transmitted light was reinjected into the plasma at different times. The laser absorption efficiency was found to be substantially improved when the transmitted light was reinjected into the plasma after adequate plasma expansion. Furthermore, through visualization experiments on gas-dynamics phenomena, it was found that the reinjection of the transmitted light affected not only the laser absorption efficiency but also the gas dynamics after breakdown, and thereby the initial flame kernel development. PMID:26906388

  6. 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.

  7. Two-dimensional plasma grating by non-collinear femtosecond filament interaction in air

    SciTech Connect

    Liu Jia; Li Wenxue; Pan Haifeng; Zeng Heping

    2011-10-10

    We experimentally demonstrated that two-dimensional (2D) plasma gratings could be generated in air by nonlinear interaction of three femtosecond filaments. The intensity interference of non-collinearly overlapped filaments was self-projected along a relatively long distance and accompanied with a wavelength-scale periodic change of the refractive index in the encircling air due to periodic plasma density modulation. The 2D plasma gratings supported 2D diffraction of the generated third-harmonic pulses. By using in-line time-resolved holographic imaging and time-delayed diffraction, the 2D plasma gratings were evidenced to last a few tens picoseconds after the excitation pulses.

  8. Plasma-catalyst coupling for volatile organic compound removal and indoor air treatment: a review

    NASA Astrophysics Data System (ADS)

    Thevenet, F.; Sivachandiran, L.; Guaitella, O.; Barakat, C.; Rousseau, A.

    2014-06-01

    The first part of the review summarizes the problem of air pollution and related air-cleaning technologies. Volatile organic compounds in particular have various effects on health and their abatement is a key issue. Different ways to couple non-thermal plasmas with catalytic or adsorbing materials are listed. In particular, a comparison between in-plasma and post-plasma coupling is made. Studies dealing with plasma-induced heterogeneous reactivity are analysed, as well as the possible modifications of the catalyst surface under plasma exposure. As an alternative to the conventional and widely studied plasma-catalyst coupling, a sequential approach has been recently proposed whereby pollutants are first adsorbed onto the material, then oxidized by switching on the plasma. Such a sequential approach is reviewed in detail.

  9. Studying astrophysical particle acceleration mechanisms with colliding magnetized laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Fox, W.; Deng, W.; Bhattacharjee, A.; Fiksel, G.; Nilson, P.; Haberberger, D.; Chang, P.-Y.; Barnak, D.

    2015-11-01

    Significant particle energization is observed to occur in many astrophysical environments, and in the standard models this acceleration occurs as a part of the energy conversion processes associated with collisionless shocks or magnetic reconnection. A recent generation of laboratory experiments conducted using magnetized laser-produced plasmas has opened opportunities to study these particle acceleration processes in the laboratory. Ablated plasma plumes are externally magnetized using an externally-applied magnetic field in combination with a low-density background plasma. Colliding unmagnetized plasmas demonstrated ion-driven Weibel instability while colliding magnetized plasmas drive magnetic reconnection. Both magnetized and unmagnetized colliding plasma are modeled with electromagnetic particle-in-cell simulations which provide an end-to-end model of the experiments. Using particle-in-cell simulations, we provide predictions of particle acceleration driven by reconnection, resulting from both direct x-line acceleration and Fermi-like acceleration at contracting magnetic fields lines near magnetic islands.

  10. The Mutation Breeding and Mutagenic Effect of Air Plasma on Penicillium Chrysogenum

    NASA Astrophysics Data System (ADS)

    Gui, Fang; Wang, Hui; Wang, Peng; Liu, Hui; Cai, Xiaochun; Hu, Yihua; Yuan, Chengling; Zheng, Zhiming

    2012-04-01

    Low temperature air plasma was used as the mutation tool for penicillin-producing strain Penicillium chrysogenum. The discharge conditions were RF power of 360 W, temperature of 40°C in a sealed chamber, and pressure of 10 Pa to 30 Pa. The result showed that the kinetics of the survival rate followed a typical saddle-shaped curve. Based on a statistic analysis, at the treating duration of 10 min, the positive mutation rate was as high as 37.5% while the negative mutation rate was low. The colonial morphology changed obviously when the plasma treating duration reached or exceeded 45 min. After both primary and secondary screening, a mutant designated as aPc051310 with high productivity of penicillin was obtained, and a strong mutagenic effect on P. chrysogenum was observed in the process. It was proved that after five generations, the mutant aPc051310 still exhibits a high productivity. All the results prove that the plasma mutation method could be developed as a convenient and effective tool to breed high-yield strains in the fermentation industry, while expanding the plasm application at the same time.

  11. Characterization Of Nano-Second Laser Induced Plasmas From Al Target In Air At Atmospheric Pressure

    SciTech Connect

    Hegazy, H.; Abdel-Rahim, F. M.; Nossair, A. M. A.; Allam, S. H.; El-Sherbini, Th. M.

    2008-09-23

    In the present work we study the effect of the laser beam energy on the properties of the plasma generated by focusing an intense laser beam on Al solid target in air at atmospheric pressure. Plasma is generated using a Nd:YAG pulsed laser at 1064 nm wavelength, 6 ns pulse duration with a maximum pulse energy of 750mJ. The emission spectrum is collected using an Echelle spectrometer equipped with ICCD camera Andor type. The measurements were performed at several delay times between 0 to 9 {mu}s. Measurements of temperature and electron density of the produced plasmas at different laser energies and at different delay times are described using different emission spectral lines. Based on LTE assumption, excitation temperature is determined from the Boltzmann plot using O I spectral lines at 777.34, 794.93, and 848.65 nm and the electron density is determined from Stark width of Al II at 281.6 and 466.3 nm. The determined density is compared with the density determined from H{sub {alpha}} spectral line.

  12. Instabilities observed at the bubble edge of a laser produced plasma during its expansion in an ambient tenuous plasma

    NASA Astrophysics Data System (ADS)

    Lee, Bo Ram; Clark, S. E.; Hoffmann, D. H. H.; Niemann, C.

    2014-10-01

    The Raptor kJ class 1053 nm Nd:Glass laser in the Phoenix laser laboratory at University of California, Los Angeles, is used to ablate a dense debris plasma from a graphite or plastic target embedded in a tenuous, uniform, and quiescent ambient magnetized plasma in the Large Plasma Device (LAPD) which provides a peak plasma density of ni ~ 1013 cm-3. Its background magnetic field can vary between 200 and 1200 G. Debris ions from laser produced plasma expand out conically with super-Alfvénic speed (MA ~ 2) and expel the background magnetic field and ambient ions to form a diamagnetic bubble. The debris plasma interacts with the ambient plasma and the magnetic field and acts as a piston which can create collisionless shocks. Flute-type instabilities, which are probably large Larmor radius Rayleigh Taylor instabilities or lower hybrid drift instabilities, are developed at the bubble edge and also observed in the experiment. The amplitude and wavelength dependence of the instabilities, which might be a strong function of debris to ambient mass to charge ratio, is studied and the experimental results are compared to the two dimensional hybrid simulations. the Deutsche Forschungsgemeinschaft in the framework of the Excellence Initiative Darmstadt Graduate School of Energy Science and Engineering (GSC1070).

  13. Enhanced laser-induced plasma channels in air

    NASA Astrophysics Data System (ADS)

    Yanlei, Zuo; Xiaofeng, Wei; Kainan, Zhou; Xiaoming, Zeng; Jingqin, Su; Zhihong, Jiao; Na, Xie; Zhaohui, Wu

    2016-03-01

    Plasma is a significant medium in high-energy density physics since it can hardly be damaged. For some applications such as plasma based backward Raman amplification (BRA), uniform high-density and large-scale plasma channels are required. In the previous experiment, the plasma transverse diameter and density are 50-200 μm and 1-2 × 1019 cm-3, here we enhance them to 0.8 mm and 8 × 1019 cm-3, respectively. Moreover, the gradient plasma is investigated in our experiment. A proper plasma gradient can be obtained with suitable pulse energy and delay. The experimental results are useful for plasma physics and nonlinear optics. Project supported by the Development Foundation of the Chinese Academy of Engineering Physics (Grant Nos. 2012A0401019 and 2013A0401019).

  14. Using Plasma-Activated High Performance Fibers with Nanocrystalline Structure in Producing New Reinforced Composite Materials

    NASA Astrophysics Data System (ADS)

    Kudinov, V.; Korneeva, N.

    2008-08-01

    A wet-pull-out method for investigation of interaction between the high performance polyethylene (HPPE) fiber and polymer matrix is discussed. The paper concerns a cold plasma technique for improving the bond of the HPPE fibers to the matrices and the fibers impregnation with the matrix. Controlled parameters are pull-out force and the height of the matrix capillary lifting along the fiber both in air and in vacuum, in combination with plasma activation of the fibers. The method allows one to estimate the wetting and impregnation of multi-filament fiber with the matrix and simultaneously measure the joint strength. Coupled action of plasma treatment and vacuum impregnation of the fibers improves the joint strength by a factor of 3. Plasma activated HPPE fibers impregnated in air show the value of shear strength τ of 4 Kg/mm2. To understand the effect of treatment initial and plasma-activated fibers were used to fabricate composite materials (CM). The properties and failure modes were compared to those of CM reinforced with untreated fibers. The failure mode of CM reinforced with plasma-activated fibers points to a high strength of the bond between the fibers and the matrix.

  15. An investigation of particle trajectories and melting in an air plasma sprayed zirconia

    SciTech Connect

    Neiser, R.A.; Roemer, T.J.

    1996-12-31

    The partially stabilized zirconia powders used to plasma spray thermal barrier coatings typically exhibit broad particle-size distributions. There are conflicting reports in the literature about the extent of injection-induced particle-sizing effects in air plasma-sprayed materials. If significant spatial separation of finer and coarser particles in the jet occurs, then one would expect it to play an important role in determining the microstructure and properties of deposits made from powders containing a wide range of particle sizes. This paper presents the results of a study in which a commercially available zirconia powder was fractionated into fine, medium, and coarse cuts and sprayed at the same torch conditions used for the ensemble powder. Diagnostic measurements of particle surface temperature, velocity, and number-density distributions in the plume for each size-cut and for the ensemble powder are reported. Deposits produced by traversing the torch back and forth to produce a raised bead were examined metallographically to study their shape and location with respect to the torch centerline and to look at their internal microstructure. The results show that, for the torch conditions used in this study, the fine, medium, and coarse size-cuts all followed the same mean trajectory. No measureable particle segregation effects were observed. Considerable differences in coatings microstructure were observed. These differences can be explained by the different particle properties measured in the plume.

  16. Properties of sintered glass-ceramics prepared from plasma vitrified air pollution control residues.

    PubMed

    Roether, J A; Daniel, D J; Rani, D Amutha; Deegan, D E; Cheeseman, C R; Boccaccini, A R

    2010-01-15

    Air pollution control (APC) residues, obtained from a major UK energy from waste (EfW) plant, processing municipal solid waste, have been blended with silica and alumina and melted using DC plasma arc technology. The glass produced was crushed, milled, uni-axially pressed and sintered at temperatures between 750 and 1150 degrees C, and the glass-ceramics formed were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mechanical properties assessed included Vickers's hardness, flexural strength, Young's modulus and thermal shock resistance. The optimum sintering temperature was found to be 950 degrees C. This produced a glass-ceramic with high density (approximately 2.58 g/cm(3)), minimum water absorption (approximately 2%) and relatively high mechanical strength (approximately 81+/-4 MPa). Thermal shock testing showed that 950 degrees C sintered samples could withstand a 700 degrees C quench in water without micro-cracking. The research demonstrates that glass-ceramics can be readily formed from DC plasma treated APC residues and that these have comparable properties to marble and porcelain. This novel approach represents a technically and commercially viable treatment option for APC residues that allow the beneficial reuse of this problematic waste.

  17. Optimizing laser produced plasmas for efficient extreme ultraviolet and soft X-ray light sources

    SciTech Connect

    Sizyuk, Tatyana; Hassanein, Ahmed

    2014-08-15

    Photon sources produced by laser beams with moderate laser intensities, up to 10{sup 14 }W/cm{sup 2}, are being developed for many industrial applications. The performance requirements for high volume manufacture devices necessitate extensive experimental research supported by theoretical plasma analysis and modeling predictions. We simulated laser produced plasma sources currently being developed for several applications such as extreme ultraviolet lithography using 13.5% ± 1% nm bandwidth, possibly beyond extreme ultraviolet lithography using 6.× nm wavelengths, and water-window microscopy utilizing 2.48 nm (La-α) and 2.88 nm (He-α) emission. We comprehensively modeled plasma evolution from solid/liquid tin, gadolinium, and nitrogen targets as three promising materials for the above described sources, respectively. Results of our analysis for plasma characteristics during the entire course of plasma evolution showed the dependence of source conversion efficiency (CE), i.e., laser energy to photons at the desired wavelength, on plasma electron density gradient. Our results showed that utilizing laser intensities which produce hotter plasma than the optimum emission temperatures allows increasing CE for all considered sources that, however, restricted by the reabsorption processes around the main emission region and this restriction is especially actual for the 6.× nm sources.

  18. DNA damage and mitochondria dysfunction in cell apoptosis induced by nonthermal air plasma

    SciTech Connect

    Kim, G. J.; Lee, J. K.; Kim, W.; Kim, K. T.

    2010-01-11

    Nonthermal plasma is known to induce animal cell death but the mechanism is not yet clear. Here, cellular and biochemical regulation of cell apoptosis is demonstrated for plasma treated cells. Surface type nonthermal air plasma triggered apoptosis of B16F10 mouse melanoma cancer cells causing DNA damage and mitochondria dysfunction. Plasma treatment activated caspase-3, apoptosis executioner. The plasma treated cells also accumulated gamma-H2A.X, marker for DNA double strand breaks, and p53 tumor suppressor gene as a response to DNA damage. Interestingly, cytochrome C was released from mitochondria and its membrane potential was changed significantly.

  19. DNA damage and mitochondria dysfunction in cell apoptosis induced by nonthermal air plasma

    NASA Astrophysics Data System (ADS)

    Kim, G. J.; Kim, W.; Kim, K. T.; Lee, J. K.

    2010-01-01

    Nonthermal plasma is known to induce animal cell death but the mechanism is not yet clear. Here, cellular and biochemical regulation of cell apoptosis is demonstrated for plasma treated cells. Surface type nonthermal air plasma triggered apoptosis of B16F10 mouse melanoma cancer cells causing DNA damage and mitochondria dysfunction. Plasma treatment activated caspase-3, apoptosis executioner. The plasma treated cells also accumulated gamma-H2A.X, marker for DNA double strand breaks, and p53 tumor suppressor gene as a response to DNA damage. Interestingly, cytochrome C was released from mitochondria and its membrane potential was changed significantly.

  20. Responses by pacific halibut to air exposure: Lack of correspondence among plasma constituents and mortality

    USGS Publications Warehouse

    Davis, M.W.; Schreck, C.B.

    2005-01-01

    Age-1 and age-2 Pacific halibut Hippoglossus stenolepis were exposed to a range of times in air (0-60 min) and air temperatures (10??C or 16??C) that simulated conditions on deck after capture to test for correspondence among responses in plasma constituents and mortality. Pacific halibut mortality generally did not correspond with cortisol, glucose, sodium, and potassium since the maximum observed plasma concentrations were reached after exposure to 30 min in air, while significant mortality occurred only after exposure to 40 min in air for age-1 fish and 60 min in air for age-2 fish. Predicting mortality in discarded Pacific halibut using these plasma constituents does not appear to be feasible. Lactate concentrations corresponded with mortality in age-1 fish exposed to 16??C and may be useful predictors of discard mortality under a limited set of fishing conditions.

  1. Colliding laser-produced plasmas: a new tool for nuclear astrophysics studies

    NASA Astrophysics Data System (ADS)

    Mascali, D.; Tudisco, S.; Bonanno, A.; Gambino, N.; Ivanovski, S.; Anzalone, A.; Gammino, S.; Miracoli, R.; Musumeci, F.

    2010-10-01

    Laser-generated plasmas, formed when a high power pulsed laser is focused onto a solid target, have been used since the 1960s. At higher power densities (>109-1010 W/cm2), such non-equilibrium plasmas expand in vacuum with supersonic velocities. Hydrodynamic simulations and experimental data show that at the beginning of the expansion the plasma temperature may reach several hundreds of eV, while the density is in the order of 1016 cm-3 or higher. Colliding laser-produced plasmas have constituted a largely unexplored and unexploited research domain until quite recent times, either for applications in materials or energy science. In this article, we propose the use of colliding laser-produced plasmas as an unique opportunity for nuclear astrophysics studies. We present a series of calculations about fusion reaction rates in laser-produced plasmas where the electron screening puzzle is taken into account. The numerical simulations have been carried out using the hydro code ZEUSMP2, while Monte Carlo codes have been used to simulate the fusion reaction rates according to the plume density and temperature evolution predicted by the simulations. We think that this type of investigation can be important in understanding the efficiency of nuclear reaction rates during the red giant phase of stellar evolution, as a significant part of the produced energy is dissipated in the low-density radiative envelope by shock waves.

  2. Apparatus for recording emissions from a rapidly generated plasma from a single plasma producing event

    DOEpatents

    Tan, T.H.; Williams, A.H.

    An optical fiber-coupled detector visible streak camera plasma diagnostic apparatus. Arrays of optical fiber-coupled detectors are placed on the film plane of several types of particle, x-ray and visible spectrometers or directly in the path of the emissions to be measured and the output is imaged by a visible streak camera. Time and spatial dependence of the emission from plasma generated from a single pulse of electromagnetic radiation or from a single particle beam burst can be recorded.

  3. Apparatus for recording emissions from a rapidly generated plasma from a single plasma producing event

    DOEpatents

    Tan, Tai Ho; Williams, Arthur H.

    1985-01-01

    An optical fiber-coupled detector visible streak camera plasma diagnostic apparatus. Arrays of optical fiber-coupled detectors are placed on the film plane of several types of particle, x-ray and visible spectrometers or directly in the path of the emissions to be measured and the output is imaged by a visible streak camera. Time and spatial dependence of the emission from plasmas generated from a single pulse of electromagnetic radiation or from a single particle beam burst can be recorded.

  4. Plasma flame for mass purification of contaminated air with chemical and biological warfare agents

    SciTech Connect

    Uhm, Han S.; Shin, Dong H.; Hong, Yong C.

    2006-09-18

    An elimination of airborne simulated chemical and biological warfare agents was carried out by making use of a plasma flame made of atmospheric plasma and a fuel-burning flame, which can purify the interior air of a large volume in isolated spaces such as buildings, public transportation systems, and military vehicles. The plasma flame generator consists of a microwave plasma torch connected in series to a fuel injector and a reaction chamber. For example, a reaction chamber, with the dimensions of a 22 cm diameter and 30 cm length, purifies an airflow rate of 5000 lpm contaminated with toluene (the simulated chemical agent) and soot from a diesel engine (the simulated aerosol for biological agents). Large volumes of purification by the plasma flame will free mankind from the threat of airborne warfare agents. The plasma flame may also effectively purify air that is contaminated with volatile organic compounds, in addition to eliminating soot from diesel engines as an environmental application.

  5. Propagation velocities of laser-produced plasmas from copper wire targets and water droplets

    NASA Technical Reports Server (NTRS)

    Song, Kyo-Dong; Alexander, Dennis R.

    1994-01-01

    Experiments were performed to determine the plasma propagation velocities resulting from KrF laser irradiation of copper wire target (75 microns diameter) and water droplets (75 microns diameter) at irradiance levels ranging from 25 to 150 GW/sq cm. Plasma propagation velocities were measured using a streak camera system oriented orthogonally to the high-energy laser propagation axis. Plasma velocities were studied as a function of position in the focused beam. Results show that both the shape of the plasma formation and material removal from the copper wire are different and depend on whether the targets are focused or slightly defocused (approximately = 0.5 mm movement in the beam axis). Plasma formation and its position relative to the target is an important factor in determining the practical focal point during high-energy laser interaction with materials. At irradiance of 100 GW/sq cm, the air plasma has two weak-velocity components which propagate toward and away from the incident laser while a strong-velocity component propagates away from the laser beam as a detonation wave. Comparison of the measured breakdown velocities (in the range of 2.22-2.27 x 10(exp 5) m/s) for air and the value calculated by the nonlinear breakdown wave theory at irradiance of 100 GW/sq cm showed a quantitative agreement within approximately 50% while the linear theory and Gaussian pulse theory failed. The detonation wave velocities of plasma generated from water droplets and copper wire targets for different focused cases were measured and analyzed theoretically. The propagation velocities of laser-induced plasma liquid droplets obtained by previous research are compared with current work.

  6. Optical Diagnostics of Air Flows Induced in Surface Dielectric Barrier Discharge Plasma Actuator

    NASA Astrophysics Data System (ADS)

    Kobatake, Takuya; Deguchi, Masanori; Suzuki, Junya; Eriguchi, Koji; Ono, Kouichi

    2014-10-01

    A surface dielectric barrier discharge (SDBD) plasma actuator has recently been intensively studied for the flow control over airfoils and turbine blades in the fields of aerospace and aeromechanics. It consists of two electrodes placed on both sides of the dielectric, where one is a top powered electrode exposed to the air, and the other is a bottom grounded electrode encapsulated with an insulator. The unidirectional gas flow along the dielectric surfaces is induced by the electrohydrodynamic (EHD) body force. It is known that the thinner the exposed electrode, the greater the momentum transfer to the air is, indicating that the thickness of the plasma is important. To analyze plasma profiles and air flows induced in the SDBD plasma actuator, we performed time-resolved and -integrated optical emission and schlieren imaging of the side view of the SDBD plasma actuator in atmospheric air. We applied a high voltage bipolar pulse (4-8 kV, 1-10 kHz) between electrodes. Experimental results indicated that the spatial extent of the plasma is much smaller than that of the induced flows. Experimental results further indicated that in the positive-going phase, a thin and long plasma is generated, where the optical emission is weak and uniform; on the other hand, in the negative-going phase, a thick and short plasma is generated, where a strong optical emission is observed near the top electrode.

  7. Generation of High-Density Electrons Based on Plasma Grating Induced Bragg Diffraction in Air

    SciTech Connect

    Shi Liping; Li Wenxue; Wang Yongdong; Lu Xin; Ding Liang'en; Zeng Heping

    2011-08-26

    Efficient nonlinear Bragg diffraction was observed as an intense infrared femtosecond pulse was focused on a plasma grating induced by interference between two ultraviolet femtosecond laser pulses in air. The preformed electrons inside the plasma grating were accelerated by subsequent intense infrared laser pulses, inducing further collisional ionization and significantly enhancing the local electron density.

  8. Targeting cancer cells with reactive oxygen and nitrogen species generated by atmospheric-pressure air plasma.

    PubMed

    Ahn, Hak Jun; Kim, Kang Il; Hoan, Nguyen Ngoc; Kim, Churl Ho; Moon, Eunpyo; Choi, Kyeong Sook; Yang, Sang Sik; Lee, Jong-Soo

    2014-01-01

    The plasma jet has been proposed as a novel therapeutic method for cancer. Anticancer activity of plasma has been reported to involve mitochondrial dysfunction. However, what constituents generated by plasma is linked to this anticancer process and its mechanism of action remain unclear. Here, we report that the therapeutic effects of air plasma result from generation of reactive oxygen/nitrogen species (ROS/RNS) including H2O2, Ox, OH-, •O2, NOx, leading to depolarization of mitochondrial membrane potential and mitochondrial ROS accumulation. Simultaneously, ROS/RNS activate c-Jun NH2-terminal kinase (JNK) and p38 kinase. As a consequence, treatment with air plasma jets induces apoptotic death in human cervical cancer HeLa cells. Pretreatment of the cells with antioxidants, JNK and p38 inhibitors, or JNK and p38 siRNA abrogates the depolarization of mitochondrial membrane potential and impairs the air plasma-induced apoptotic cell death, suggesting that the ROS/RNS generated by plasma trigger signaling pathways involving JNK and p38 and promote mitochondrial perturbation, leading to apoptosis. Therefore, administration of air plasma may be a feasible strategy to eliminate cancer cells.

  9. Characterization of an atmospheric pressure air plasma source for polymer surface modification

    NASA Astrophysics Data System (ADS)

    Yang, Shujun; Tang, Jiansheng

    2013-10-01

    An atmospheric pressure air plasma source was generated through dielectric barrier discharge (DBD). It was used to modify polyethyleneterephthalate (PET) surfaces with very high throughput. An equivalent circuit model was used to calculate the peak average electron density. The emission spectrum from the plasma was taken and the main peaks in the spectrum were identified. The ozone density in the down plasma region was estimated by Absorption Spectroscopy. NSF and ARC-ODU

  10. Late-time particle emission from laser-produced graphite plasma

    SciTech Connect

    Harilal, S. S.; Hassanein, A.; Polek, M.

    2011-09-01

    We report a late-time ''fireworks-like'' particle emission from laser-produced graphite plasma during its evolution. Plasmas were produced using graphite targets excited with 1064 nm Nd: yttrium aluminum garnet (YAG) laser in vacuum. The time evolution of graphite plasma was investigated using fast gated imaging and visible emission spectroscopy. The emission dynamics of plasma is rapidly changing with time and the delayed firework-like emission from the graphite target followed a black-body curve. Our studies indicated that such firework-like emission is strongly depended on target material properties and explained due to material spallation caused by overheating the trapped gases through thermal diffusion along the layer structures of graphite.

  11. Experimental Investigation of Short Scalelength Density Fluctuations in Laser-Produced Plasmas

    SciTech Connect

    Moody, J.D.; MacGowan, B.J.; Glenzer, S.H.; Kirkwood, R.K.; Kruer, W.L.; Williams, E.A.; Stone, G.F.; Montgomery, D.S.; Schmitt, A.J.

    1999-11-01

    The technique of near forward laser. scattering is used to infer characteristics of intrinsic and controlled density fluctuations in laser-produced plasmas. Intrinsic fluctuations are studied in long scalelength plasmas where the fluctuations exhibit scale sizes related to the size of the intensity variations in the plasma forming and interaction beams. Stimulated Brillouin forward scattering and filamentation appear to be the primary mechanism through which these fluctuations originate. The beam spray which results from these fluctuations is important to understand since it can affect symmetry in an inertial confinement fusion (ICF) experiment. Controlled fluctuations are studied in foam and exploding foil targets. Forward scattered light from foam targets shows evidence that the initial target inhomogeneities remain after the target is laser heated. Forward scattered light from an exploding foil plasma shows that a regular intensity pattern can be used to produce a spatially correlated density fluctuation pattern. These results provide data which can be used to benchmark numerical models of beam spray.

  12. Numerical Investigation of Radiative Heat Transfer in Laser Induced Air Plasmas

    NASA Technical Reports Server (NTRS)

    Liu, J.; Chen, Y. S.; Wang, T. S.; Turner, James E. (Technical Monitor)

    2001-01-01

    Radiative heat transfer is one of the most important phenomena in the laser induced plasmas. This study is intended to develop accurate and efficient methods for predicting laser radiation absorption and plasma radiative heat transfer, and investigate the plasma radiation effects in laser propelled vehicles. To model laser radiation absorption, a ray tracing method along with the Beer's law is adopted. To solve the radiative transfer equation in the air plasmas, the discrete transfer method (DTM) is selected and explained. The air plasma radiative properties are predicted by the LORAN code. To validate the present nonequilibrium radiation model, several benchmark problems are examined and the present results are found to match the available solutions. To investigate the effects of plasma radiation in laser propelled vehicles, the present radiation code is coupled into a plasma aerodynamics code and a selected problem is considered. Comparisons of results at different cases show that plasma radiation plays a role of cooling plasma and it lowers the plasma temperature by about 10%. This change in temperature also results in a reduction of the coupling coefficient by about 10-20%. The present study indicates that plasma radiation modeling is very important for accurate modeling of aerodynamics in a laser propelled vehicle.

  13. Measurement of Noise Produced by a Plasma Contactor Operating in Ground Based Facilities

    NASA Technical Reports Server (NTRS)

    Snyder, Steve

    1996-01-01

    Methods to measure electric field fluctuations accurately in a plasma with an active monopole antenna are described. It is shown that the conductive surfaces of the antenna must be adequately isolated from the ambient plasma and that the monopole must be sufficiently short to avoid antenna amplifier saturation. Experimental results illustrate that the noise produced by plasma contactor operation and sensed by the antenna is due to plasma phenomena and is not induced by laboratory power supplies. A good correlation is shown between the current fluctuations in the contactor electrical circuit and the noise detected by the antenna. A large body of experimental data support the conclusion that the majority of noise sensed by the antenna at frequencies less than 1 MHz is due to current fluctuations (electrostatic waves) in the plasma adjacent to the antenna and not to electromagnetic wave radiation. Caution is suggested when comparing antenna noise measurements to conventional specifications for radiated emissions.

  14. Fokker Planck and Krook theory of energetic electron transport in a laser produced plasma

    SciTech Connect

    Manheimer, Wallace; Colombant, Denis

    2015-09-15

    Various laser plasma instabilities, such as the two plasma decay instability and the stimulated Raman scatter instability, produce large quantities of energetic electrons. How these electrons are transported and heat the plasma are crucial questions for laser fusion. This paper works out a Fokker Planck and Krook theory for such transport and heating. The result is a set of equations, for which one can find a simple asymptotic approximation for the solution, for the Fokker Planck case, and an exact solution for the Krook case. These solutions are evaluated and compared with one another. They give rise to expressions for the spatially dependent heating of the background plasma, as a function of the instantaneous laser and plasma parameters, in either planar or spherical geometry. These formulas are simple, universal (depending weakly only on the single parameter Z, the charge state), and can be easily be incorporated into a fluid simulation.

  15. Time Evolution of Kelvin-Helmholtz Vortices Associated with Collisionless Shocks in Laser-produced Plasmas

    NASA Astrophysics Data System (ADS)

    Kuramitsu, Y.; Mizuta, A.; Sakawa, Y.; Tanji, H.; Ide, T.; Sano, T.; Koenig, M.; Ravasio, A.; Pelka, A.; Takabe, H.; Gregory, C. D.; Woolsey, N.; Moritaka, T.; Matsukiyo, S.; Matsumoto, Y.; Ohnishi, N.

    2016-09-01

    We report experimental results on Kelvin–Helmholtz (KH) instability and resultant vortices in laser-produced plasmas. By irradiating a double plane target with a laser beam, asymmetric counterstreaming plasmas are created. The interaction of the plasmas with different velocities and densities results in the formation of asymmetric shocks, where the shear flow exists along the contact surface and the KH instability is excited. We observe the spatial and temporal evolution of plasmas and shocks with time-resolved diagnostics over several shots. Our results clearly show the evolution of transverse fluctuations, wavelike structures, and circular features, which are interpreted as the KH instability and resultant vortices. The relevant numerical simulations demonstrate the time evolution of KH vortices and show qualitative agreement with experimental results. Shocks, and thus the contact surfaces, are ubiquitous in the universe; our experimental results show general consequences where two plasmas interact.

  16. Time Evolution of Kelvin-Helmholtz Vortices Associated with Collisionless Shocks in Laser-produced Plasmas

    NASA Astrophysics Data System (ADS)

    Kuramitsu, Y.; Mizuta, A.; Sakawa, Y.; Tanji, H.; Ide, T.; Sano, T.; Koenig, M.; Ravasio, A.; Pelka, A.; Takabe, H.; Gregory, C. D.; Woolsey, N.; Moritaka, T.; Matsukiyo, S.; Matsumoto, Y.; Ohnishi, N.

    2016-09-01

    We report experimental results on Kelvin-Helmholtz (KH) instability and resultant vortices in laser-produced plasmas. By irradiating a double plane target with a laser beam, asymmetric counterstreaming plasmas are created. The interaction of the plasmas with different velocities and densities results in the formation of asymmetric shocks, where the shear flow exists along the contact surface and the KH instability is excited. We observe the spatial and temporal evolution of plasmas and shocks with time-resolved diagnostics over several shots. Our results clearly show the evolution of transverse fluctuations, wavelike structures, and circular features, which are interpreted as the KH instability and resultant vortices. The relevant numerical simulations demonstrate the time evolution of KH vortices and show qualitative agreement with experimental results. Shocks, and thus the contact surfaces, are ubiquitous in the universe; our experimental results show general consequences where two plasmas interact.

  17. Effect of transverse magnetic field on laser produced plasma expansion into vacuum

    SciTech Connect

    Bennaceur-Doumaz, D.; Djebli, M.

    2011-08-15

    A one-dimensional time-dependent magneto-hydrodynamic ideal model is used to investigate the dynamics of initially magnetized laser produced plasma expansion into vacuum, in the context of inertial fusion. The plasma is assumed to be fully ionized and in local thermodynamic equilibrium (LTE), allowing all charged particles to have the same temperatures. Self-similar solution shows that the density, velocity, and temperature increase with the strength of the magnetic field. The transverse magnetic field causes significant changes in the plasma expansion dynamics, including the plasma confinement. The plasma velocity increasing is also observed and the temperature is found to be larger compared to temperature in un-magnetized case.

  18. Fokker Planck and Krook theory of energetic electron transport in a laser produced plasma

    NASA Astrophysics Data System (ADS)

    Manheimer, Wallace; Colombant, Denis

    2015-09-01

    Various laser plasma instabilities, such as the two plasma decay instability and the stimulated Raman scatter instability, produce large quantities of energetic electrons. How these electrons are transported and heat the plasma are crucial questions for laser fusion. This paper works out a Fokker Planck and Krook theory for such transport and heating. The result is a set of equations, for which one can find a simple asymptotic approximation for the solution, for the Fokker Planck case, and an exact solution for the Krook case. These solutions are evaluated and compared with one another. They give rise to expressions for the spatially dependent heating of the background plasma, as a function of the instantaneous laser and plasma parameters, in either planar or spherical geometry. These formulas are simple, universal (depending weakly only on the single parameter Z, the charge state), and can be easily be incorporated into a fluid simulation.

  19. Open-air direct current plasma jet: Scaling up, uniformity, and cellular control

    NASA Astrophysics Data System (ADS)

    Wu, S.; Wang, Z.; Huang, Q.; Lu, X.; Ostrikov, K.

    2012-10-01

    Atmospheric-pressure plasma jets are commonly used in many fields from medicine to nanotechnology, yet the issue of scaling the discharges up to larger areas without compromising the plasma uniformity remains a major challenge. In this paper, we demonstrate a homogenous cold air plasma glow with a large cross-section generated by a direct current power supply. There is no risk of glow-to-arc transitions, and the plasma glow appears uniform regardless of the gap between the nozzle and the surface being processed. Detailed studies show that both the position of the quartz tube and the gas flow rate can be used to control the plasma properties. Further investigation indicates that the residual charges trapped on the inner surface of the quartz tube may be responsible for the generation of the air plasma plume with a large cross-section. The spatially resolved optical emission spectroscopy reveals that the air plasma plume is uniform as it propagates out of the nozzle. The remarkable improvement of the plasma uniformity is used to improve the bio-compatibility of a glass coverslip over a reasonably large area. This improvement is demonstrated by a much more uniform and effective attachment and proliferation of human embryonic kidney 293 (HEK 293) cells on the plasma-treated surface.

  20. OH(A,X) radicals in microwave plasma-assisted combustion of methane/air

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Fuh, Che; Wang, Chuji; Laser Spectroscopy and Plasma Team

    2014-10-01

    A novel microwave plasma-assisted combustion (PAC) system, which consists of a microwave plasma-assisted combustor, a gas flow control manifold, and a set of optical diagnostic systems, was developed as a new test platform to study plasma enhancement of combustion. Using this system, we studied the state-resolved OH(A,X) radicals in the plasma-assisted combustion and ignition of a methane/air mixture. Experimental results identified three reaction zones in the plasma-assisted combustor: the plasma zone, the hybrid plasma-flame zone, and the flame zone. The OH(A) radicals in the three distinct zones were characterized using optical emission spectroscopy (OES). Results showed a surge of OH(A) radicals in the hybrid zone compared to the plasma zone and the flame zone. The OH(X) radicals in the flame zone were measured using cavity ringdown spectroscopy (CRDS), and the absolute number density distribution of OH(X) was quantified in two-dimension. The effect of microwave argon plasma on combustion was studied with two different fuel/oxidizer injection patterns, namely the premixed methane/air injection and the nonpremixed (separate) methane/air injection. Parameters investigated included the flame geometry, the lean flammability limit, the emission spectra, and rotational temperature. State-resolved OH(A,X) radicals in the PAC of both injection patterns were also compared. This work is supported by the National Science Foundation through the Grant No. CBET-1066486.

  1. Open-air direct current plasma jet: Scaling up, uniformity, and cellular control

    SciTech Connect

    Wu, S.; Wang, Z.; Huang, Q.; Lu, X.; Ostrikov, K.

    2012-10-15

    Atmospheric-pressure plasma jets are commonly used in many fields from medicine to nanotechnology, yet the issue of scaling the discharges up to larger areas without compromising the plasma uniformity remains a major challenge. In this paper, we demonstrate a homogenous cold air plasma glow with a large cross-section generated by a direct current power supply. There is no risk of glow-to-arc transitions, and the plasma glow appears uniform regardless of the gap between the nozzle and the surface being processed. Detailed studies show that both the position of the quartz tube and the gas flow rate can be used to control the plasma properties. Further investigation indicates that the residual charges trapped on the inner surface of the quartz tube may be responsible for the generation of the air plasma plume with a large cross-section. The spatially resolved optical emission spectroscopy reveals that the air plasma plume is uniform as it propagates out of the nozzle. The remarkable improvement of the plasma uniformity is used to improve the bio-compatibility of a glass coverslip over a reasonably large area. This improvement is demonstrated by a much more uniform and effective attachment and proliferation of human embryonic kidney 293 (HEK 293) cells on the plasma-treated surface.

  2. Short-pulse laser-produced plasma from C60 molecules

    SciTech Connect

    Wuelker, Cornelius; Theobald, Wolfgang; Ouw, Donald; Schaefer, Fritz P.; Chichkov, Boris N.

    1995-05-01

    The first experimental observations of a plasma produced in a vapor of C60 molecules with a high-intensity subpicosecond KrF laser (6x10{sup 15} W/cm{sup 2}) are reported. It differs from a plasma created in an ordinary carbon preplasma by reaching much higher ionization stages under the same experimental conditions. This remarkable property of C60 molecules (and other clusters) opens new prospects for short-pulse driven X-ray lasers.

  3. Plasma waves produced by the xenon ion beam experiment on the Porcupine sounding rocket

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.; Kelley, M.

    1982-01-01

    The production of electrostatic ion cyclotron waves by a perpendicular ion beam in the F-region ionosphere is described. The ion beam experiment was part of the Porcupine program and produced electrostatic hydrogen cyclotron waves just above harmonics of the hydrogen cyclotron frequency. The plasma process may be thought of as a magnetized background ionosphere through which an unmagnetized beam is flowing. The dispersion equation for this hypothesis is constructed and solved. Preliminary solutions agree well with the observed plasma waves.

  4. Plasma enclosed in a magnetic field produced by flexible surface magnets.

    PubMed

    Schott, L

    1978-04-01

    A homogeneous steady state plasma with a usable volume of approximately 200 l and with an electron temperature of 1-2 eV and a plasma density of approximately 10(9)-10(10) cm(-3) is produced in a discharge chamber the outside of whose walls is covered with flexible magnetic strips. This magnet arrangement can be built at a fraction of the cost of a conventional system using rigid surface magnets. The magnetic multipole field leads to an increase of the plasma density by one to two orders of magnitude and it is also found to cause trapping of high energy electrons originating from the discharge region.

  5. On the atomic state densities of plasmas produced by the ``torche à injection axiale''

    NASA Astrophysics Data System (ADS)

    Jonkers, J.; Vos, H. P. C.; van der Mullen, J. A. M.; Timmermans, E. A. H.

    1996-04-01

    The atomic state densities of helium and argon plasmas produced by the microwave driven plasma torch called the "torche à injection axiale" are presented. They are obtained by absolute line intensity measurements of the excited states and by applying the ideal gas law to the ground state. It will be shown that the atomic state distribution function (ASDF) does not obey the Saha-Boltzmann law: the ASDF cannot be described by one temperature. From the shape of the ASDF it can be concluded that the plasma is ionising. By extrapolating the measured state densities towards the ionisation limit, a minimum value of the electron density can be determined.

  6. Axial distribution of a VHF H2 plasma produced by a narrow gap discharge

    NASA Astrophysics Data System (ADS)

    Chen, Kuan-Chen; Chen, Chia-Fu; Lien, Cheng-Yang; Chiu, Kuo-Feng; Shi, Jen-Bin; Tsai, Yu-Jer; Lien, Ting-Kuei; Ogiwara, Kohei; Uchino, Kiichiro; Kawai, Yoshinobu

    2016-01-01

    A capacitively coupled VHF H2 plasma was produced with a conventional parallel plate electrode of 400 × 300 mm2. Axial distributions of the plasma parameters were examined using a movable Langmuir probe. The electron density had a hill-like profile near the center while the electron temperature around the discharge electrode was higher than that near the center. It was found that the axial distribution of the plasma potential was considerably different from that based on ohmic heating. The measured sheath potentials around the discharge electrode were lower than the theoretical potentials. A simulation using a hybrid model was performed and compared the results with the experimental results.

  7. A plasma needle for generating homogeneous discharge in atmospheric pressure air

    SciTech Connect

    Li Xuechen; Yuan Ning; Jia Pengying; Chen Junying

    2010-09-15

    Homogeneous discharge in air is often considered to be the ultimate low-temperature atmospheric pressure plasmas for industrial applications. In this paper, we present a method whereby stable homogeneous discharge in open air can be generated by a simple plasma needle. The discharge mechanism is discussed based on the spatially resolved light emission waveforms from the plasma. Optical emission spectroscopy is used to determine electron energy and rotational temperature, and results indicate that both electron energy and rotational temperature increase with increasing the applied voltage. The results are analyzed qualitatively based on the discharge mechanism.

  8. Experimental discovery of charge-exchange-caused dips in spectral lines from laser-produced plasmas.

    PubMed

    Leboucher-Dalimier, E; Oks, E; Dufour, E; Sauvan, P; Angelo, P; Schott, R; Poquerusse, A

    2001-12-01

    We report the first experimental observation of charge-exchange-caused dips (also called x dips) in spectral lines of multicharged ions in laser-produced plasmas. Specifically, in the process of a laser irradiation of targets made out of aluminum carbide, we observed two x dips in the Ly(gamma) line of Al XIII perturbed by fully stripped carbon. From the practical point of view, this opens up a way to experimentally produce not-yet-available fundamental data on charge exchange between multicharged ions, virtually inaccessible by other experimental methods. From the theoretical viewpoint, the results are important because the x dips are the only one signature of charge exchange in profiles of spectral lines emitted by plasmas and they are the only one quasimolecular phenomenon that could be observed at relatively "low" densities of laser-produced plasmas. PMID:11736229

  9. Surface analysis using a new plasma assisted desorption/ionisation source for mass spectrometry in ambient air

    NASA Astrophysics Data System (ADS)

    Bowfield, A.; Barrett, D. A.; Alexander, M. R.; Ortori, C. A.; Rutten, F. M.; Salter, T. L.; Gilmore, I. S.; Bradley, J. W.

    2012-06-01

    The authors report on a modified micro-plasma assisted desorption/ionisation (PADI) device which creates plasma through the breakdown of ambient air rather than utilising an independent noble gas flow. This new micro-PADI device is used as an ion source for ambient mass spectrometry to analyse species released from the surfaces of polytetrafluoroethylene, and generic ibuprofen and paracetamol tablets through remote activation of the surface by the plasma. The mass spectra from these surfaces compare favourably to those produced by a PADI device constructed using an earlier design and confirm that the new ion source is an effective device which can be used to achieve ambient mass spectrometry with improved spatial resolution.

  10. Plasma test on industrial diamond powder in hydrogen and air for fracture strength study

    NASA Astrophysics Data System (ADS)

    Chary, Rohit Asuri Sudharshana

    Diamonds are the most precious material all over the world. Ever since their discovery, the desire for natural diamonds has been great; recently, the demand has steeply increased, leading to scarcity. For example, in 2010, diamonds worth $50 billion were marketed. This increased demand has led to discovering alternative sources to replace diamonds. The diamond, being the hardest material on earth, could be replaced with no other material except another diamond. Thus, the industrial or synthetic diamond was invented. Because of extreme hardness is one of diamond's properties, diamonds are used in cutting operations. The fracture strength of diamond is one of the crucial factors that determine its life time as a cutting tool. Glow discharge is one of the techniques used for plasma formation. The glow discharge process is conducted in a vacuum chamber by ionizing gas atoms. Ions penetrate into the atomic structure, ejecting a secondary electron. The objective of this study is to determine the change in fracture strength of industrial diamond powder before and after plasma treatment. This study focuses mainly on the change in crystal defects and crushing strength (CS) of industrial diamond powder after the penetration of hydrogen gas, air and hydrogen-air mixture ions into the sample powder. For this study, an industrial diamond powder sample of 100 carats weight, along with its average fracture strength value was received from Engis Corporation, Illinois. The sample was divided into parts, each weighing 10-12 carats. At the University of Nevada, Las Vegas (UNLV), a plasma test was conducted on six sample parts for a total of 16 hours on each part. The three gas types mentioned above were used during plasma tests, with the pressure in vacuum chamber between 200 mTorr and 2 Torr. The plasma test on four sample parts was in the presence of hydrogen-air mixture. The first sample had chamber pressures between 200 mTorr and 400 mTorr. The remaining three samples had chamber

  11. Apparatus and method to enhance X-ray production in laser produced plasmas

    DOEpatents

    Augustoni, A.L.; Gerardo, J.B.; Raymond, T.D.

    1992-12-29

    Method and apparatus for generating x-rays for use in, for instance, x-ray photolithography is disclosed. The method of generating x-rays includes the steps of providing a target and irradiating the target with a laser system which produces a train of sub-pulses to generate an x-ray producing plasma. The sub-pulses are of both high intensity and short duration. The apparatus for generating x-rays from a plasma includes a vacuum chamber, a target supported within the chamber and a laser system, including a short storage time laser. 8 figs.

  12. Apparatus and method to enhance X-ray production in laser produced plasmas

    DOEpatents

    Augustoni, Arnold L.; Gerardo, James B.; Raymond, Thomas D.

    1992-01-01

    Method and apparatus for generating x-rays for use in, for instance, x-ray photolithography. The method of generating x-rays includes the steps of providing a target and irradiating the target with a laser system which produces a train of sub-pulses to generate an x-ray producing plasma. The sub-pulses are of both high intensity and short duration. The apparatus for generating x-rays from a plasma includes a vacuum chamber, a target supported within the chamber and a laser system, including a short storage time laser.

  13. A Novel Technique to Treat Air Leak Following Lobectomy: Intrapleural Infusion of Plasma

    PubMed Central

    Konstantinou, Froso; Potaris, Konstantinos; Syrigos, Konstantinos N.; Tsipas, Panteleimon; Karagkiouzis, Grigorios; Konstantinou, Marios

    2016-01-01

    Background Persistent air leak following pulmonary lobectomy can be very difficult to treat and results in prolonged hospitalization. We aimed to evaluate the efficacy of a new method of postoperative air leak management using intrapleurally infused fresh frozen plasma via the chest tube. Material/Methods Between June 2008 and June 2014, we retrospectively reviewed 98 consecutive patients who underwent lobectomy for lung cancer and postoperatively developed persistent air leak treated with intrapleural instillation of fresh frozen plasma. Results The study identified 89 men and 9 women, with a median age of 65.5 years (range 48–77 years), with persistent postoperative air leak. Intrapleural infusion of fresh frozen plasma was successful in stopping air leaks in 90 patients (92%) within 24 hours, and in 96 patients (98%) within 48 hours, following resumption of the procedure. In the remaining 2, air leak ceased at 14 and 19 days. Conclusions Intrapleural infusion of fresh frozen plasma is a safe, inexpensive, and remarkably effective method for treatment of persistent air leak following lobectomy for lung cancer. PMID:27079644

  14. Simulated experiment for elimination of air contaminated with odorous chemical agents by microwave plasma burner

    SciTech Connect

    Hong, Yong Cheol; Shin, Dong Hun; Uhm, Han Sup

    2007-10-15

    An experimental study on elimination of odorous chemical agent was carried out by making use of a microwave plasma burner, which consists of a microwave plasma torch and a reaction chamber with a fuel injector. Injection of hydrocarbon fuels into a high-temperature microwave torch plasma generates a plasma flame. The plasma flame can eliminate the odorous chemical agent diluted in air or purify the interior air of a large volume in isolated spaces. The specially designed reaction chamber eliminated H{sub 2}S and NH{sub 3} diluted in airflow rate of 5000 lpm (liters per minute), showing {beta} values of 46.52 and 39.69 J/l, respectively.

  15. Phenol production in benzene/air plasmas at atmospheric pressure. Role of radical and ionic routes.

    PubMed

    Ascenzi, Daniela; Franceschi, Pietro; Guella, Graziano; Tosi, Paolo

    2006-06-29

    Benzene can be efficiently converted into phenol when it is treated by either corona or dielectric barrier discharge (DBD) plasmas operating at atmospheric pressure in air or mixtures of N(2) and O(2). Phenol produced by corona discharge in an atmospheric pressure chemical ionization source (APCI) has been detected as the corresponding radical cation C(6)H(5)OH(+*) at m/z 94 by an ion trap mass spectrometer. On the other hand, phenol has been observed also as neutral product by gas chromatography-mass spectrometry analysis (GC-MS) after treatment in a DBD plasma. Experiments aimed at shading light on the elementary processes responsible for benzene oxidation were carried out (i) by changing the composition of the gas in the corona discharge source; (ii) by using isotopically labeled reagents; and (iii) by investigating some relevant ion-molecule reactions (i.e. C(6)H(6)(+*) + O(2), C(6)H(5)(+) + O(2)) via selected guided ion beam measurements and with the help of ab initio calculations. The results of our approach show that ionic mechanisms do not play a significant role in phenol production, which can be better explained by radical reactions resulting in oxygen addition to the benzene ring followed by 1,2 H transfer.

  16. Plasma decay in the afterglow of a high-voltage nanosecond discharge in air

    SciTech Connect

    Aleksandrov, N. L.; Anokhin, E. M.; Kindysheva, S. V.; Kirpichnikov, A. A.; Kosarev, I. N.; Nudnova, M. M.; Starikovskaya, S. M.; Starikovskii, A. Yu.

    2012-02-15

    The decay of air plasma produced by a high-voltage nanosecond discharge at room temperature and gas pressures in the range of 1-10 Torr was studied experimentally and theoretically. The time dependence of the electron density was measured with a microwave interferometer. The initial electron density was about 10{sup 12} cm{sup -3}. The discharge homogeneity was monitored using optical methods. The dynamics of the charged particle densities in the discharge afterglow was simulated by numerically solving the balance equations for electron and ions and the equation for the electron temperature. It was shown that, under these experimental conditions, plasma electrons are mainly lost due to dissociative and three-body recombination with ions. Agreement between the measured and calculated electron densities was achieved only when the rate constant of the three-body electron-ion recombination was increased by one order of magnitude and the temperature dependence of this rate constant was modified. This indicates that the mechanism for three-body recombination of molecular ions differs from that of the well-studied mechanism of atomic ion recombination.

  17. Fabrication and Characterization of Amorphous Alumina-Yttria-Stabilized Zirconia Coatings by Air Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Song, Xuemei; Suhonen, Tomi; Varis, Tommi; Huang, Liping; Zheng, Xuebin; Zeng, Yi

    2014-12-01

    Almost fully amorphous coatings of near-eutectic alumina-yttria-stabilized zirconia (Al2O3-YSZ) were prepared by air plasma spraying using Al2O3 and 8 mol.% YSZ crystalline-mixed powders. The coatings consist of mostly an amorphous phase with a small amount of nanocrystals. Various characterization techniques were used to understand coating formation and the origins of the different phases within the coatings. The formation of the mostly amorphous structure is attributed to the high glass-forming ability of Al2O3-YSZ and the appropriate plasma spraying conditions. A small number of nanocrystals are produced during crystallization of the incoming molten droplets or by recrystallization of the solidified splats by accumulated heat. Scanning electron microscopy shows that the coatings have a dense, layered structure with low porosity, and bright-field transmission electron microscopy images indicate sharp interface rather than grit-blasted wavy surface between splats and substrates in the coatings. The as-sprayed amorphous coatings crystallized at around 920 °C and micro-hardness of the as-sprayed amorphous coatings was 8.12 GPa.

  18. Fast tomographic measurements of temperature in an air plasma cutting torch

    NASA Astrophysics Data System (ADS)

    Hlína, J.; Šonský, J.; Gruber, J.; Cressault, Y.

    2016-03-01

    Temperatures in an air plasma jet were measured using a tomographic experimental arrangement providing time-resolved scans of plasma optical radiation in the spectral band 559-601 nm from two directions. The acquired data and subsequent processing yielded time-resolved temperature distributions in measurement planes perpendicular to the plasma jet axis with a temporal resolution of 1 μs. The measurement system and evaluation methods afforded detailed information about the influence of high-frequency ripple modulation of the arc current on plasma temperature.

  19. Characteristics of a Direct Current-driven plasma jet operated in open air

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Di, Cong; Jia, Pengying; Bao, Wenting

    2013-09-01

    A DC-driven plasma jet has been developed to generate a diffuse plasma plume by blowing argon into the ambient air. The plasma plume, showing a cup shape with a diameter of several centimeters at a higher voltage, is a pulsed discharge despite a DC voltage is applied. The pulse frequency is investigated as a function of the voltage under different gap widths and gas flow rates. Results show that plasma bullets propagate from the hollow needle to the plate electrode by spatially resolved measurement. A supposition about non-electroneutral trail of the streamer is proposed to interpret these experimental phenomena.

  20. Characteristics of a Direct Current-driven plasma jet operated in open air

    SciTech Connect

    Li, Xuechen; Bao, Wenting; Di, Cong; Jia, Pengying

    2013-09-30

    A DC-driven plasma jet has been developed to generate a diffuse plasma plume by blowing argon into the ambient air. The plasma plume, showing a cup shape with a diameter of several centimeters at a higher voltage, is a pulsed discharge despite a DC voltage is applied. The pulse frequency is investigated as a function of the voltage under different gap widths and gas flow rates. Results show that plasma bullets propagate from the hollow needle to the plate electrode by spatially resolved measurement. A supposition about non-electroneutral trail of the streamer is proposed to interpret these experimental phenomena.

  1. Influence of the focal point position on the properties of a laser-produced plasma

    SciTech Connect

    Kasperczuk, A.; Pisarczyk, T.; Badziak, J.; Miklaszewski, R.; Parys, P.; Rosinski, M.; Wolowski, J.; Stenz, CH.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P.

    2007-10-15

    This paper deals with investigations of the influence of the focusing lens focal point position on the properties of a plasma produced by a defocused laser beam. The experiment was carried out at the Prague Asterix Laser System iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikova, J. Krasa, E. Krousky, P. Krupickova, L. Laska, K. Masek, T. Mocek, M. Pfeifer, A. Prag, O. Renner, K. Rohlena, B. Rus, J. Skala, P. Straka, and J. Ullschmied, Phys. Plasmas 8, 2495 (2001)] by using the third harmonic of laser radiation ({lambda}=0.438 {mu}m), laser energy of 70 J, pulse duration of 250 ps (full width at half-maximum), and beam spot radii of 250 and 400 {mu}m. Cu and Ta were chosen as target materials. The experimental data were obtained by means of a three-frame interferometric system, ion collectors, and crater replica techniques. The reported results allow formulating an important hypothesis that the laser-produced plasma modifies strongly the laser intensity distribution. It is shown how such a modification depends on the relative position and distance of the focal point to the target surface. Of particular importance is whether the focal point is located inside or in front of the target. The irradiation geometry is crucial for the possibility of generating plasma jets by laser radiation. Well-formed jet-like plasma structures can be created if an initially homogeneous laser intensity distribution is transformed in the plasma to an annular one.

  2. Influence of the focal point position on the properties of a laser-produced plasma

    NASA Astrophysics Data System (ADS)

    Kasperczuk, A.; Pisarczyk, T.; Badziak, J.; Miklaszewski, R.; Parys, P.; Rosinski, M.; Wolowski, J.; Stenz, CH.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P.

    2007-10-01

    This paper deals with investigations of the influence of the focusing lens focal point position on the properties of a plasma produced by a defocused laser beam. The experiment was carried out at the Prague Asterix Laser System iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikova, J. Krasa, E. Krousky, P. Krupickova, L. Laska, K. Masek, T. Mocek, M. Pfeifer, A. Prag, O. Renner, K. Rohlena, B. Rus, J. Skala, P. Straka, and J. Ullschmied, Phys. Plasmas 8, 2495 (2001)] by using the third harmonic of laser radiation (λ=0.438μm), laser energy of 70J, pulse duration of 250ps (full width at half-maximum), and beam spot radii of 250 and 400μm. Cu and Ta were chosen as target materials. The experimental data were obtained by means of a three-frame interferometric system, ion collectors, and crater replica techniques. The reported results allow formulating an important hypothesis that the laser-produced plasma modifies strongly the laser intensity distribution. It is shown how such a modification depends on the relative position and distance of the focal point to the target surface. Of particular importance is whether the focal point is located inside or in front of the target. The irradiation geometry is crucial for the possibility of generating plasma jets by laser radiation. Well-formed jet-like plasma structures can be created if an initially homogeneous laser intensity distribution is transformed in the plasma to an annular one.

  3. Dynamics of neutrals and ions in an ultrafast laser produced Zn plasma

    SciTech Connect

    Smijesh, N.; Rao, Kavya H.; Philip, Reji

    2015-03-15

    Optical time of flight dynamics of neutrals and ions in an ultrafast laser produced zinc plasma generated by irradiating a solid zinc target using 100 fs laser pulses is investigated. An acceleration of ions is observed which arises from internal Coulomb forces acting between charged species in the plasma. Some of the fast ions recombine with electrons in the plasma and generate fast neutrals. Plasma plume imaging performed at various ambient pressures indicates adiabatic expansion at lower pressures and plume front deceleration at higher pressures: at lower pressures the plume front-time (R-t) plot displays a linear expansion, shock wave model fits to the data at 5 Torr and at higher pressures the data fits better to the drag model. Furthermore, around an intermediate pressure of 10 Torr, the R-t plot fits to the shock wave model at earlier stages of plasma expansion, while it fits to the drag model at the later stages. These investigations provide relevant information on the acceleration of ions and neutrals in an expanding zinc plasma plume produced by ultrafast laser pulses.

  4. Spatio-temporal evolution of uranium emission in laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Harilal, S. S.; Diwakar, P. K.; LaHaye, N. L.; Phillips, M. C.

    2015-09-01

    Laser-induced plasma spectroscopy provides much impetus as a nuclear forensics tool because of its capability of standoff detection and real-time analysis. However, special nuclear materials like U, Pu, etc. provide very crowded spectra and, when combined with shifts and broadening of spectral lines caused by ambient atmospheric operation, generate a complex plasma spectroscopy system. We explored the spatio-temporal evolution of excited U species in a laser ablation plume under various ambient pressure conditions. Plasmas were generated using 1064 nm, 6 ns pulses from a Nd:YAG laser on a U containing glass matrix target. The role of air ambient pressure on U line intensities, signal-to-background ratios, and linewidths were investigated. Spatially and temporally resolved optical time-of-flight emission spectroscopy of excited uranium atoms were used for studying the expansion hydrodynamics and the persistence of U species in the plume. Our results showed that U emission linewidths increased with pressure due to increased Stark broadening; however, the broadening was less than that for Ca. A comparison with U emission features in the presence of an inert gas showed the persistence of U species in plasmas in ambient air is significantly reduced; this could be due to oxide and other reactive species formation.

  5. Four-color laser diagnostics for Z-pinch and laser-produced plasma.

    PubMed

    Ivanov, V V; Anderson, A A; Begishev, I A

    2016-01-20

    Four-color laser diagnostics were developed for Z-pinch and laser plasma at the 1 MA pulsed power generator. Four harmonics of the Nd:YAG laser at wavelengths of 1064, 532, 266, and 213 nm were produced during the cascade conversion in three nonlinear crystals and propagated together in one beampath. Deep UV probing allows better penetration of the dense plasma. Laser probing at four wavelengths allows observation of plasma in a wide range of densities in one shot of the diagnostic laser. Examples of four-color laser shadowgraphy and interferometry of the wire-array load and laser plasma interaction are presented and discussed. PMID:26835923

  6. Angular distribution of ions and extreme ultraviolet emission in laser-produced tin droplet plasma

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Wang, Xinbing; Duan, Lian; Lan, Hui; Chen, Ziqi; Zuo, Duluo; Lu, Peixiang

    2015-05-01

    Angular-resolved ion time-of-flight spectra as well as extreme ultraviolet radiation in laser-produced tin droplet plasma are investigated experimentally and theoretically. Tin droplets with a diameter of 150 μm are irradiated by a pulsed Nd:YAG laser. The ion time-of-flight spectra measured from the plasma formed by laser irradiation of the tin droplets are interpreted in terms of a theoretical elliptical Druyvesteyn distribution to deduce ion density distributions including kinetic temperatures of the plasma. The opacity of the plasma for extreme ultraviolet radiation is calculated based on the deduced ion densities and temperatures, and the angular distribution of extreme ultraviolet radiation is expressed as a function of the opacity using the Beer-Lambert law. Our results show that the calculated angular distribution of extreme ultraviolet radiation is in satisfactory agreement with the experimental data.

  7. Properties of a capillary discharge-produced argon plasma waveguide for shorter wavelength source application

    SciTech Connect

    Sakai, Shohei; Miyazawa, Jun; Higashiguchi, Takeshi; Yugami, Noboru; Bobrova, Nadezhda; Sasorov, Pavel; Sentoku, Yasuhiko; Kodama, Ryosuke

    2011-10-15

    We report the operation of a discharge-produced argon (Ar) plasma waveguide in an alumina (Al{sub 2}O{sub 3}) capillary to guide a 10{sup 16}-W/cm{sup 2} ultrashort laser pulse for shorter wavelength light sources at high repetition rate operation. The electron density in the plasma channel was measured to be 1 x 10{sup 18} cm{sup -3}. Modeling with a one-dimensional magnetrohydrodynamic code was used to evaluate the degree of ionization of Ar in the preformed plasma channel. The observed spectrum of the laser pulse after propagation in the argon plasma waveguide was not modified and was well reproduced by a particle in cell simulation.

  8. Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas

    SciTech Connect

    Coons, R. W.; Harilal, S. S.; Campos, D.; Hassanein, A.

    2010-09-15

    Tin and lithium plasmas emit efficiently in the in-band region (13.5 nm with 2% bandwidth) necessary for extreme ultraviolet (EUV) lithography. We have made a detailed comparison of the atomic and ionic debris, as well as the emission features of Sn and Li plasmas under identical experimental conditions. Planar slabs of pure Sn and Li were irradiated with 1064 nm, 9 ns neodymium-doped yttrium aluminum garnet laser pulses for producing plasmas. A suite of diagnostics were used to analyze the emission and debris features, including optical emission spectroscopy (OES), a Faraday cup, an EUV pinhole camera, the absolute measurement of EUV conversion efficiency (CE), etc. Our results show that Sn plasmas provide a CE nearly twice that of Li. However, the kinetic energies of Sn ions are considerably higher, though with a lower flux. OES studies have showed that the kinetic energies of neutral species are substantially lower compared to that of the charged particle species.

  9. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    SciTech Connect

    Rosenberg, M. J.; Li, C. K.; Fox, W.; Igumenshchev, I.; Seguin, F. H.; Town, R. P.; Frenje, J. A.; Stoeckl, C.; Glebov, V.; Petrasso, R. D.

    2015-04-08

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β~10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell (PIC) simulations predict a stronger flux compression and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.

  10. Angular distribution of ions and extreme ultraviolet emission in laser-produced tin droplet plasma

    SciTech Connect

    Chen, Hong; Duan, Lian; Lan, Hui; Wang, Xinbing Chen, Ziqi; Zuo, Duluo; Lu, Peixiang

    2015-05-21

    Angular-resolved ion time-of-flight spectra as well as extreme ultraviolet radiation in laser-produced tin droplet plasma are investigated experimentally and theoretically. Tin droplets with a diameter of 150 μm are irradiated by a pulsed Nd:YAG laser. The ion time-of-flight spectra measured from the plasma formed by laser irradiation of the tin droplets are interpreted in terms of a theoretical elliptical Druyvesteyn distribution to deduce ion density distributions including kinetic temperatures of the plasma. The opacity of the plasma for extreme ultraviolet radiation is calculated based on the deduced ion densities and temperatures, and the angular distribution of extreme ultraviolet radiation is expressed as a function of the opacity using the Beer–Lambert law. Our results show that the calculated angular distribution of extreme ultraviolet radiation is in satisfactory agreement with the experimental data.

  11. Apoptotic effects on cultured cells of atmospheric-pressure plasma produced using various gases

    NASA Astrophysics Data System (ADS)

    Tominami, Kanako; Kanetaka, Hiroyasu; Kudo, Tada-aki; Sasaki, Shota; Kaneko, Toshiro

    2016-01-01

    This study investigated the effects of low-temperature atmospheric-pressure plasma on various cells such as rat fibroblastic Rat-1 cell line, rat neuroblastoma-like PC12 cell line, and rat macrophage-like NR8383 cell line. The plasma was irradiated directly to a culture medium containing plated cells for 0-20 s. The applied voltage, excitation frequency, and argon or helium gas flow were, respectively, 3-6 kV, 10 kHz, and 3 L/min. Cell viability and apoptotic activity were evaluated using annexin-V/propidium iodide staining. Results showed that the low-temperature atmospheric-pressure plasma irradiation promoted cell death in a discharge-voltage-dependent and irradiation-time-dependent manner. Furthermore, different effects are produced depending on the cell type. Moreover, entirely different mechanisms might be responsible for the induction of apoptosis in cells by helium and argon plasma.

  12. Optical breakdown threshold investigation of 1064 nm laser induced air plasmas

    SciTech Connect

    Thiyagarajan, Magesh; Thompson, Shane

    2012-04-01

    We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 {mu}m radius spot size that produces laser intensities up to 3 - 6 TW/cm{sup 2}, sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10{sup 8} nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then

  13. Understanding Potential Air Emissions from a Cellulosic Biorefinery Producing Renewable Diesel Blendstock.

    SciTech Connect

    Zhang, Yimin; Heath, Garvin A.; Renzaglia, Jason; Thomas, Mae

    2015-06-22

    The Energy Independence and Security Act of 2007, through the Renewable Fuel Standard (RFS), mandates increased use of biofuels, including cellulosic biofuels. The RFS is expected to spur the development of advanced biofuel technologies (e.g., new and innovative biofuel conversion pathways) as well as the construction of biorefineries (refineries that produce biofuels) using these technologies. To develop sustainable cellulosic biofuels, one of the goals of the Bioenergy Technologies Office (BETO) at the Department of Energy is to minimize air pollutants from the entire biofuel supply chain, as stated in their 2014 Multi-Year Program Plan (2014). Although biofuels in general have been found to have lower life cycle greenhouse gas (GHG) emissions compared to petroleum fuels on an energy basis, biomass feedstock production, harvesting, transportation, processing and conversion are expected to emit a wide range of other air pollutants (e.g., criteria air pollutants, hazardous air pollutants), which could affect the environmental benefits of biofuels when displacing petroleum fuels. While it is important for policy makers, air quality planners and regulators, biofuel developers, and investors to understand the potential implications on air quality from a growing biofuel industry, there is a general lack of information and knowledge about the type, fate and magnitude of potential air pollutant emissions from the production of cellulosic biofuels due to the nascent stage of this emerging industry. This analysis assesses potential air pollutant emissions from a hypothetical biorefinery, selected by BETO for further research and development, which uses a biological conversion process of sugars to hydrocarbons to produce infrastructural-compatible renewable diesel blendstock from cellulosic biomass.

  14. The AMY experiment: Microwave emission from air shower plasmas

    NASA Astrophysics Data System (ADS)

    Alvarez-Muñiz, J.; Blanco, M.; Boháčová, M.; Buonomo, B.; Cataldi, G.; Coluccia, M. R.; Creti, P.; De Mitri, I.; Di Giulio, C.; Facal San Luis, P.; Foggetta, L.; Gaïor, R.; Garcia-Fernandez, D.; Iarlori, M.; Le Coz, S.; Letessier-Selvon, A.; Louedec, K.; Maris, I. C.; Martello, D.; Mazzitelli, G.; Monasor, M.; Perrone, L.; Petrera, S.; Privitera, P.; Rizi, V.; Rodriguez Fernandez, G.; Salamida, F.; Salina, G.; Settimo, M.; Valente, P.; Vazquez, J. R.; Verzi, V.; Williams, C.

    2016-07-01

    You The Air Microwave Yield (AMY) experiment investigate the molecular bremsstrahlung radiation emitted in the GHz frequency range from an electron beam induced air-shower. The measurements have been performed at the Beam Test Facility (BTF) of Frascati INFN National Laboratories with a 510 MeV electron beam in a wide frequency range between 1 and 20 GHz. We present the apparatus and the results of the tests performed.

  15. Plasma shield for in-air beam processesa)

    NASA Astrophysics Data System (ADS)

    Hershcovitch, Ady

    2008-05-01

    A novel concept/apparatus, the Plasma Shield, is introduced in this paper. The purpose of the Plasma Shield is designed to shield a target object chemically and thermally by engulfing an area subjected to beam treatment with inert plasma. The shield consists of a vortex-stabilized arc that is employed to shield beams and workpiece area of interaction from an atmospheric or liquid environment. A vortex-stabilized arc is established between a beam generating device (laser, ion or electron gun) and a target object. The arc, which is composed of a pure noble gas, engulfs the interaction region and shields it from any surrounding liquids like water or reactive gases. The vortex is composed of a sacrificial gas or liquid that swirls around and stabilizes the arc. The successful Plasma Shield was experimentally established and very high-quality electron beam welding with partial plasma shielding was performed. The principle of the operation and experimental results are discussed in the paper.

  16. Plasma shield for in-air beam processes

    SciTech Connect

    Hershcovitch, Ady

    2008-05-15

    A novel concept/apparatus, the Plasma Shield, is introduced in this paper. The purpose of the Plasma Shield is designed to shield a target object chemically and thermally by engulfing an area subjected to beam treatment with inert plasma. The shield consists of a vortex-stabilized arc that is employed to shield beams and workpiece area of interaction from an atmospheric or liquid environment. A vortex-stabilized arc is established between a beam generating device (laser, ion or electron gun) and a target object. The arc, which is composed of a pure noble gas, engulfs the interaction region and shields it from any surrounding liquids like water or reactive gases. The vortex is composed of a sacrificial gas or liquid that swirls around and stabilizes the arc. The successful Plasma Shield was experimentally established and very high-quality electron beam welding with partial plasma shielding was performed. The principle of the operation and experimental results are discussed in the paper.

  17. Atmospheric cold plasma inactivation of Escherichia coli, Salmonella enterica serovar Typhimurium and Listeria monocytogenes inoculated on fresh produce.

    PubMed

    Ziuzina, D; Patil, S; Cullen, P J; Keener, K M; Bourke, P

    2014-09-01

    Atmospheric cold plasma (ACP) represents a potential alternative to traditional methods for non-thermal decontamination of foods. In this study, the antimicrobial efficacy of a novel dielectric barrier discharge ACP device against Escherichia coli, Salmonella enterica Typhimurium and Listeria monocytogenes inoculated on cherry tomatoes and strawberries, was examined. Bacteria were spot inoculated on the produce surface, air dried and sealed inside a rigid polypropylene container. Samples were indirectly exposed (i.e. placed outside plasma discharge) to a high voltage (70 kVRMS) air ACP and subsequently stored at room temperature for 24 h. ACP treatment for 10, 60 and 120 s resulted in reduction of Salmonella, E. coli and L. monocytogenes populations on tomato to undetectable levels from initial populations of 3.1, 6.3, and 6.7 log10 CFU/sample, respectively. However, an extended ACP treatment time was necessary to reduce bacterial populations attached on the more complex surface of strawberries. Treatment time for 300 s resulted in reduction of E. coli, Salmonella and L. monocytogenes populations by 3.5, 3.8 and 4.2 log10 CFU/sample, respectively, and also effectively reduced the background microflora of tomatoes. PMID:24929725

  18. Atmospheric cold plasma inactivation of Escherichia coli, Salmonella enterica serovar Typhimurium and Listeria monocytogenes inoculated on fresh produce.

    PubMed

    Ziuzina, D; Patil, S; Cullen, P J; Keener, K M; Bourke, P

    2014-09-01

    Atmospheric cold plasma (ACP) represents a potential alternative to traditional methods for non-thermal decontamination of foods. In this study, the antimicrobial efficacy of a novel dielectric barrier discharge ACP device against Escherichia coli, Salmonella enterica Typhimurium and Listeria monocytogenes inoculated on cherry tomatoes and strawberries, was examined. Bacteria were spot inoculated on the produce surface, air dried and sealed inside a rigid polypropylene container. Samples were indirectly exposed (i.e. placed outside plasma discharge) to a high voltage (70 kVRMS) air ACP and subsequently stored at room temperature for 24 h. ACP treatment for 10, 60 and 120 s resulted in reduction of Salmonella, E. coli and L. monocytogenes populations on tomato to undetectable levels from initial populations of 3.1, 6.3, and 6.7 log10 CFU/sample, respectively. However, an extended ACP treatment time was necessary to reduce bacterial populations attached on the more complex surface of strawberries. Treatment time for 300 s resulted in reduction of E. coli, Salmonella and L. monocytogenes populations by 3.5, 3.8 and 4.2 log10 CFU/sample, respectively, and also effectively reduced the background microflora of tomatoes.

  19. Plasma-chemical method for producing metal oxide powders and their application

    NASA Astrophysics Data System (ADS)

    Zhukov, I.; Vorozhtsov, S.; Promakhov, V.; Bondarchuk, I.; Zhukov, A.; Vorozhtsov, A.

    2015-11-01

    Structure and properties of ZrO2 and Al2O3 powders produced using plasma chemical technique were studied in the framework of this research. Obtained Al2O3 powder was used for reinforcement of Al alloy. Improvement of mechanical properties of Al alloy associated with introduction of alumina particles into the melt was demonstrated.

  20. Towards laboratory-produced relativistic electron-positron pair-plasmas

    SciTech Connect

    Chen, H; Wilks, S C; Meyerhofer, D D; Beiersdorfer, P; Cauble, R; Dollar, F; Falk, K; Hazi, A; Murphy, C D; Park, J; Seely, J; Szabo, C I; Shepherd, R; Tommasini, R; Zulick, K

    2010-08-31

    Relativistic pair-plasmas and jets are believed to exist in many astrophysical objects and are often invoked to explain energetic phenomena related to Gamma Ray Bursts and Black Holes. On earth, positrons from radioactive isotopes or accelerators are used extensively at low energies (sub-MeV) in areas related to surface science positron emission tomography and basic antimatter science. Experimental platforms capable of producing the high-temperature pair-plasma and high-flux jets required to simulate astrophysical positron conditions have so far been absent. In the last few years, we performed extensive experiments generating positrons with intense lasers where we found that relativistic electron and positron jets are produced by irradiating a solid gold target with an intense picosecond laser pulse. The positron temperatures in directions parallel and transverse to the beam both exceeded 0.5 MeV, and the density of electrons and positrons in these jets are of order 10{sup 16} cm{sup -3} and 10{sup 13} cm{sup -3}, respectively. With the advent of high-energy ultra-short laser pulses, we expect that a charge-neutral, relativistic pair-plasma is achievable, a novel regime of laboratory-produced hot dense matter. This talk will present some details of the laser-produced pair-plasma experiments.

  1. Experimental observation of cavitons and rarefaction waves in laser-produced plasma

    SciTech Connect

    Briand, J.; Tamer, M.E.; Adrian, V.; Gomes, A.; Quemener, Y.; Kieffer, J.C.; Dinguirard, J.P.

    1984-10-01

    A Wollaston's prism interferometer and a 632.9 nm probe beam having a 10 psec (FWHM) pulse are used to detect the electron density profile instabilities in a 1.06 ..mu..m laser-produced plasma. Experimental observations of cavitons and rarefaction waves are presented and discussed for a laser irradiance of 10/sup 15/ W/cm/sup 2/.

  2. A scheme to produce high density and high temperature plasma for opacity measurement

    SciTech Connect

    Xu, Yan; Wu, SiZhong; Zheng, WuDi

    2015-04-15

    The opacity of shock-compressed material is of general scientific interest for astrophysical plasmas and for inertial confinement fusion research. A proposal is suggested to produce high temperature plasma with density around 1 g/cm{sup −3}. Two types of opacity target (the sandwich target and the foam enhanced sandwich target) are investigated numerically. The foam enhanced sandwich target has structure of foam–solid-sample-solid-foam. The foam will increase laser absorption efficiency and the ablating pressure. Hydrodynamic simulations confirm that the laser can be fully absorbed by the under-critical-density foam and a faster shock is produced inside the CH layer. High intensity lasers heat opacity target from both sides. The CH layers must be thick enough to keep the laser away from the sample. The laser-driven shocks move inward and collide at the center. Part of their kinetic energy is converted into internal energy and high density and high temperature local thermodynamic equilibrium sample plasma is produced. The plasma produced by laser heating the foam enhanced sandwich target has higher sample temperature than by laser heating the sandwich target. It may be useful for measuring the opacity of shock compressed material in laboratory.

  3. Degradation of volatile organic compounds in a non-thermal plasma air purifier.

    PubMed

    Schmid, Stefan; Jecklin, Matthias C; Zenobi, Renato

    2010-03-01

    The degradation of volatile organic compounds in a commercially available non-thermal plasma based air purifying system was investigated. Several studies exist that interrogate the degradation of VOCs in closed air systems using a non-thermal plasma combined with a heterogeneous catalyst. For the first time, however, our study was performed under realistic conditions (normal indoor air, 297.5K and 12.5 g m(-3) water content) on an open system, in the absence of an auxiliary catalyst, and using standard operating air flow rates (up to 320 L min(-1)). Cyclohexene, benzene, toluene, ethylbenzene and the xylene isomers were nebulized and guided through the plasma air purifier. The degradation products were trapped by activated charcoal tubes or silica gel tubes, and analyzed using gas chromatography mass spectrometry. Degradation efficiencies of 11+/-1.6% for cyclohexene, <2% for benzene, 11+/-2.4% for toluene, 3+/-1% for ethylbenzene, 1+/-1% for sigma-xylene, and 3+/-0.4% for m-/rho-xylene were found. A fairly wide range of degradation products could be identified. On both trapping media, various oxidized species such as alcohols, aldehydes, ketones and one epoxide were observed. The formation of adipaldehyde from nebulized cyclohexene clearly indicates an ozonolysis reaction. Other degradation products observed suggests reactions with OH radicals. We propose that mostly ozone and OH radicals are responsible for the degradation of organic molecules in the plasma air purifier. PMID:20167347

  4. 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.

  5. Air surface microdischarge-photon synergy in antibacterial plasma-activated water

    NASA Astrophysics Data System (ADS)

    Graves, David; Pavlovich, Mathew; Chang, Hung-Wen; Sakiyama, Yuki; Clark, Douglas

    2013-09-01

    We show that the antibacterial effects of air plasma on water can be amplified by synergy with ultraviolet (UV) photons. We use the surface microdischarge configuration (SMD) in atmospheric air adjacent to bacteria-laden water coupled with UVA (360 nm) photons from a light emitting diode (LED) to demonstrate this synergy. Air SMD, especially if operated in a confined space, can operate in different modes: low power mode (<0.1 W/cm2) generates primarily O3 whereas higher powers generate mainly nitrogen oxides; we focus here on the latter. The nitrogen oxide mode creates a powerful antibacterial mixture in water, including NO2-, NO3- and H2O2. Although these species alone can be strongly antibacterial, especially at low pH, we show that addition of UVA photons greatly amplifies the antibacterial effect. We first measured log reductions with only photons and then only plasma. Only when UVA exposes water after plasma does the synergy appear. Synergy appears to be due to UVA photolysis of plasma-generated NO2- to form NO and OH. We conclude that combining plasma-generated chemical species with activating photons can amplify and strengthen plasma effectiveness in many biological and other applications. Supported by Department of Energy, Office of Fusion Science Plasma Science Center.

  6. 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)

  7. A simple atmospheric pressure room-temperature air plasma needle device for biomedical applications

    NASA Astrophysics Data System (ADS)

    Lu, X.; Xiong, Z.; Zhao, F.; Xian, Y.; Xiong, Q.; Gong, W.; Zou, C.; Jiang, Z.; Pan, Y.

    2009-11-01

    Rather than using noble gas, room air is used as the working gas for an atmospheric pressure room-temperature plasma. The plasma is driven by submicrosecond pulsed directed current voltages. Several current spikes appear periodically for each voltage pulse. The first current spike has a peak value of more than 1.5 A with a pulse width of about 10 ns. Emission spectra show that besides excited OH, O, N2(C-B), and N2+(B-X) emission, excited NO, N2(B-A), H, and even N emission are also observed in the plasma, which indicates that the plasma may be more reactive than that generated by other plasma jet devices. Utilizing the room-temperature plasma, preliminary inactivation experiments show that Enterococcus faecalis can be killed with a treatment time of only several seconds.

  8. Morphological and structural effects on tungsten targets produced by fusion plasma pulses from a table top plasma focus

    NASA Astrophysics Data System (ADS)

    Inestrosa-Izurieta, M. J.; Ramos-Moore, E.; Soto, L.

    2015-09-01

    A table top plasma focus device operating at hundreds of joules was used to simulate an equivalent damage factor than the obtained on the divertor in tokamak experiments. Using the ejected plasma produced after the pinch disruptions, the effects on tungsten targets from 50 cumulative plasma shocks with power fluxes per shot between 2.6 and 9200 kW cm-2 and with a duration time in the order of tens of nanoseconds (damage factor in the order of 100-103 (W cm-2)s1/2) were studied. Morphological analysis shows an increasing appearance of cracked surfaces with holes, fissures and defects, suggesting a potential progression of stress effects and a fast heat load that melts the surface, ending in thermal contractions that recrystallize the surface of the target. A structural analysis demonstrates a compressive stress development and suggests that part of the energy is released in the melting of the surface in case of a plasma shock with a power flux of 9.2 MW cm-2, 75 ns duration pulse, 2.5   ×   103 (W cm-2)s1/2 damage factor. How to increase the damage factor by one order of magnitude up to the expected value from type I ELMs on the ITER divertor, i.e. 104 (W cm-2)s1/2 is discussed.

  9. The cold and atmospheric-pressure air surface barrier discharge plasma for large-area sterilization applications

    SciTech Connect

    Wang Dacheng; Zhao Di; Feng Kecheng; Zhang Xianhui; Liu Dongping; Yang Size

    2011-04-18

    This letter reports a stable air surface barrier discharge device for large-area sterilization applications at room temperature. This design may result in visually uniform plasmas with the electrode area scaled up (or down) to the required size. A comparison for the survival rates of Escherichia coli from air, N{sub 2} and O{sub 2} surface barrier discharge plasmas is presented, and the air surface plasma consisting of strong filamentary discharges can efficiently kill Escherichia coli. Optical emission measurements indicate that reactive species such as O and OH generated in the room temperature air plasmas play a significant role in the sterilization process.

  10. The influence of target irradiation conditions on the parameters of laser-produced plasma jets

    NASA Astrophysics Data System (ADS)

    Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P.

    2007-03-01

    Recent experimental results demonstrate that the forming of plasma jets is a fundamental process accompanying the laser-produced plasma expansion, if a massive planar target with relatively high atomic number is irradiated by a defocused laser beam. In this paper some new results on the influence of target irradiation conditions on plasma jet parameters are presented. The experiment was carried out at the Prague Asterix Laser System (PALS) iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikova, J. Krasa, E. Krousky, P. Krupickova, L. Laska, K. Masek, A. Prag, O. Renner, K. Rohlena, B. Rus, J. Skala, P. Straka, and J. Ullschmied, Phys. Plasmas 8, 2495 (2001)]. with the third harmonic beam of the pulse duration of 250ps. The beam energies varied in the range of 13-160J. The planar massive targets used in the experiment were made of copper. For measurements of the electron density evolution a three frame interferometric system was employed. The jets were produced in the whole range of the laser energy used. Calculations of the efficiency of the plasma jet production show that it decreases with increasing the laser energy.

  11. The influence of target irradiation conditions on the parameters of laser-produced plasma jets

    SciTech Connect

    Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Rohlena, K.; Skala, J.; Pisarczyk, P.

    2007-03-15

    Recent experimental results demonstrate that the forming of plasma jets is a fundamental process accompanying the laser-produced plasma expansion, if a massive planar target with relatively high atomic number is irradiated by a defocused laser beam. In this paper some new results on the influence of target irradiation conditions on plasma jet parameters are presented. The experiment was carried out at the Prague Asterix Laser System (PALS) iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikova, J. Krasa, E. Krousky, P. Krupickova, L. Laska, K. Masek, A. Prag, O. Renner, K. Rohlena, B. Rus, J. Skala, P. Straka, and J. Ullschmied, Phys. Plasmas 8, 2495 (2001)]. with the third harmonic beam of the pulse duration of 250 ps. The beam energies varied in the range of 13-160 J. The planar massive targets used in the experiment were made of copper. For measurements of the electron density evolution a three frame interferometric system was employed. The jets were produced in the whole range of the laser energy used. Calculations of the efficiency of the plasma jet production show that it decreases with increasing the laser energy.

  12. Development of a Catalytic Wet Air Oxidation Method to Produce Feedstock Gases from Waste Polymers

    NASA Technical Reports Server (NTRS)

    Kulis, Michael J.; Guerrero-Medina, Karen J.; Hepp, Aloysius F.

    2012-01-01

    Given the high cost of space launch, the repurposing of biological and plastic wastes to reduce the need for logistical support during long distance and long duration space missions has long been recognized as a high priority. Described in this paper are the preliminary efforts to develop a wet air oxidation system in order to produce fuels from waste polymers. Preliminary results of partial oxidation in near supercritical water conditions are presented. Inherent corrosion and salt precipitation are discussed as system design issues for a thorough assessment of a second generation wet air oxidation system. This work is currently being supported by the In-Situ Resource Utilization Project.

  13. Characterization of the Horizontal Confinement Produced by a Glass Box in a Complex Plasma

    NASA Astrophysics Data System (ADS)

    Bradshaw, Jace; Douglass, Angela

    2013-10-01

    The majority of plasmas in the visible universe are complex plasmas, consisting of not only electrons, ions, and neutral particles, but also small, usually micron-sized particles called ``dust.'' Recent complex plasma experiments have placed a glass box on the lower electrode of a GEC RF reference cell in order to alter the electric confinement experienced by micrometer-sized particles in the plasma. While this has led to interesting observations, such as vertical chains and Coulomb balls, the nature of the confinement is not well understood. In this experiment, a single melamine formaldehyde dust particle was levitated in the plasma sheath and contained by a glass box. The dust particle was then struck by a laser pulse to perturb the particle from its equilibrium position. The trajectory of the particle was analyzed to determine the nature of the electric potential produced by the walls of the glass box. Trials were run with varying pressures, particle sizes, box sizes, and plasma powers to determine the effect of each parameter on the confinement.

  14. The diagnostics of ultra-short pulse laser-produced plasma

    NASA Astrophysics Data System (ADS)

    Roth, Markus

    2011-09-01

    Since the invention of the laser, coherent light has been used to break down solid or gaseous material and transform it into a plasma. Over the last three decades two things have changed. Due to multiple advancements and design of high power lasers it is now possible to increase the electric and magnetic field strength that pushed the electron motion towards the regime of relativistic plasma physics. Moreover, due to the short pulse duration of the driving laser the underlying physics has become so transient that concepts like thermal equilibrium (even a local one) or spatial isotropy start to fail. Consequently short pulse laser-driven plasmas have become a rich source of new phenomena that we are just about beginning to explore. Such phenomena, like particle acceleration, nuclear laser-induced reactions, the generation of coherent secondary radiation ranging from THz to high harmonics and the production of attosecond pulses have excited an enormous interest in the study of short pulse laser plasmas. The diagnostics of such ultra-short pulse laser plasmas is a challenging task that involves many and different techniques compared to conventional laser-produced plasmas. While this review cannot cover the entire field of diagnostics that has been developed over the last years, we will try to give a summarizing description of the most important techniques that are currently being used.

  15. Spatio-temporal mapping of ablated species in ultrafast laser-produced graphite plasmas

    SciTech Connect

    Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A.

    2012-05-28

    We studied the spatial and temporal distributions of ionic, neutral, and molecular species generated by femtosecond laser produced plasma under varying ambient nitrogen gas pressures. Plasmas were generated by irradiating planar graphite targets using 40 fs pulses of 800 nm radiation from a Ti:Sapphire laser. The results show that in the presence of an ambient gas, the molecular species spatial extension and lifetime are directly correlated to the evolution of excited ions. The present studies also provide valuable insights into the evolution history of various species and their excitation during ultrafast laser ablation.

  16. Characterization of laser-produced carbon plasmas relevant to laboratory astrophysics

    NASA Astrophysics Data System (ADS)

    Schaeffer, D. B.; Bondarenko, A. S.; Everson, E. T.; Clark, S. E.; Constantin, C. G.; Niemann, C.

    2016-07-01

    Experiments, analytic modeling, and numerical simulations are presented to characterize carbon plasmas produced by high-intensity ( 109-1013 W cm-2) lasers relevant to experimental laboratory astrophysics. In the large-scale limit, the results agree well with a self-similar isentropic, adiabatic fluid model. Laser-target simulations, however, show small-scale structure in the velocity distribution of different ion species, which is also seen in experiments. These distributions indicate that most of the plasma energy resides in moderate charge states (C+3-C+4), most of the mass resides in the lowest charge states, and the highest charge states move fastest.

  17. Diamagnetic cavitization of laser-produced barium plasma in transverse magnetic field.

    PubMed

    Raju, Makaraju Srinivasa; Singh, R K; Kumar, Ajai; Gopinath, Pramod

    2015-05-15

    Influence of uniform transverse magnetic field and ambient Ar pressure on the plasma plume produced by Nd:YAG laser ablation of barium has been investigated by time-of-flight optical emission spectroscopy. Experiments were carried out with laser pulse energy of 150 mJ and 0.45 Tesla magnetic field. The time-of-flight profiles showed ambient pressure independent behavior at 6-mm distance from the target, which is attributed to the diamagnetic behavior of the laser plasma. A theoretical model is proposed that may explain the compression of temporal profiles of the ionic lines. PMID:26393695

  18. Effect of plasma suppression additives on electrodynamic characteristics of the torch discharge burning in the air

    NASA Astrophysics Data System (ADS)

    Vidyaev, D.; Lutsenko, Yu; Boretsky, E.

    2016-06-01

    The paper shows the results of measurements of wave number of electromagnetic wave, which supports burning of high-frequency torch discharge in the mixture of air with water vapor and carbon dioxide. The nonmonotonic dependence of attenuation factor of electromagnetic waves is set on a concentration of water vapor. It is shown that the attenuation degree of electromagnetic field in the plasma with water vapor significantly exceeds the attenuation degree of electromagnetic field in the plasma with carbon dioxide.

  19. Effects of system parameters on the physical characteristics of bubbles produced through air sparging.

    PubMed

    Burns, S E; Zhang, M

    2001-01-01

    Air sparging is a relatively new, cost-effective technology for the remediation of soil and groundwater contaminated with volatile organic compounds (VOCs). While the method has met with reasonable success at a large number of field sites, implementation of the technique is restricted to relatively coarse-grained soils with large values of air permeability, which significantly limits its applicability. An understanding of the fundamental parameters that control the formation and distribution of air in the sparging process is useful for optimizing the system implementation and extending its range of applicability. This work presents the results of an experimental investigation into the effect of process control parameters on the size and size distribution of air bubbles produced in aqueous and idealized saturated porous media systems. The experiments used digital image analysis to image and quantify the physical characteristics of the bubbles generated in a bench scale test cell. Results demonstrated that the average bubble size and range of size distribution increased as the injection pressure and size of the injection orifice were increased. Larger diameter bubbles with wider size distributions were produced in the presence of particles when compared to aqueous systems. As the particle size was decreased, the size of bubbles produced increased. Finally, the presence of trace quantities of the surfactant Triton X100 led to uniformly small diameter bubbles under all experimental conditions. The presence of the surfactant coating produced bubbles with physical characteristics that are more suited to in situ stripping of VOCs than the bubbles produced in the absence of a surfactant. PMID:11352012

  20. Effects of system parameters on the physical characteristics of bubbles produced through air sparging.

    PubMed

    Burns, S E; Zhang, M

    2001-01-01

    Air sparging is a relatively new, cost-effective technology for the remediation of soil and groundwater contaminated with volatile organic compounds (VOCs). While the method has met with reasonable success at a large number of field sites, implementation of the technique is restricted to relatively coarse-grained soils with large values of air permeability, which significantly limits its applicability. An understanding of the fundamental parameters that control the formation and distribution of air in the sparging process is useful for optimizing the system implementation and extending its range of applicability. This work presents the results of an experimental investigation into the effect of process control parameters on the size and size distribution of air bubbles produced in aqueous and idealized saturated porous media systems. The experiments used digital image analysis to image and quantify the physical characteristics of the bubbles generated in a bench scale test cell. Results demonstrated that the average bubble size and range of size distribution increased as the injection pressure and size of the injection orifice were increased. Larger diameter bubbles with wider size distributions were produced in the presence of particles when compared to aqueous systems. As the particle size was decreased, the size of bubbles produced increased. Finally, the presence of trace quantities of the surfactant Triton X100 led to uniformly small diameter bubbles under all experimental conditions. The presence of the surfactant coating produced bubbles with physical characteristics that are more suited to in situ stripping of VOCs than the bubbles produced in the absence of a surfactant.

  1. Simulation of cold atmospheric plasma component composition and particle densities in air

    NASA Astrophysics Data System (ADS)

    Kirsanov, Gennady; Chirtsov, Alexander; Kudryavtsev, Anatoliy

    2015-11-01

    Recently discharges in air at atmospheric pressure were the subject of numerous studies. Of particular interest are the cold streams of air plasma, which contains large amounts of chemically active species. It is their action can be decisive in the interaction with living tissues. Therefore, in addition to its physical properties, it is important to know the component composition and particle densities. The goal was to develop a numerical model of atmospheric pressure glow microdischarge in air with the definition of the component composition of plasma. To achieve this goal the task was divided into two sub-tasks, in the first simulated microdischarge atmospheric pressure in air using a simplified set of plasma chemical reactions in order to obtain the basic characteristics of the discharge, which are the initial approximations in the problem of the calculation of the densities with detailed plasma chemistry, including 53 spices and over 600 chemical reactions. As a result of the model was created, which can be adapted for calculating the component composition of plasma of various sources. Calculate the density of particles in the glow microdischarges and dynamics of their change in time.

  2. Simulation of cold atmospheric plasma component composition and particle densities in air

    NASA Astrophysics Data System (ADS)

    Kirsanov, Gennady; Bekasov, Vladimir; Eliseev, Stepan; Kudryavtsev, Anatoly; Sisoev, Sergey

    2015-11-01

    Recently discharges in air at atmospheric pressure were the subject of numerous studies. Of particular interest are the cold streams of air plasma, which contains large amounts of chemically active species. It is their action can be decisive in the interaction with living tissues. Therefore, in addition to its physical properties, it is important to know the component composition and particle densities. The goal was to develop a numerical model of atmospheric pressure glow microdischarge in air with the definition of the component composition of plasma. To achieve this goal the task was broken down into two sub-tasks, in the first simulated microdischarge atmospheric pressure in air using a simplified set of plasma chemical reactions in order to obtain the basic characteristics of the discharge, which are the initial approximations in the problem of the calculation of the densities with detailed plasma chemistry, including 53 spices and over 600 chemical reactions. As a result of the model was created, which can be adapted for calculating the component composition of plasma of various sources. Calculate the density of particles in the glow microdischarges and dynamics of their change in time.

  3. Temporal evolution of femtosecond laser induced plasma filament in air and N{sub 2}

    SciTech Connect

    Papeer, J.; Botton, M.; Zigler, A.; Gordon, D.; Sprangle, P.

    2013-12-09

    We present single shot, high resolution, time-resolved measurements of the relaxation of laser induced plasma filaments in air and in N{sub 2} gas. Based on the measurements of the time dependent electromagnetic signal in a waveguide, an accurate and simple derivation of the electron density in the filament is demonstrated. This experimental method does not require prior knowledge of filament dimensions or control over its exact spatial location. The experimental results are compared to numerical simulations of air plasma chemistry. Results reveal the role of various decay mechanisms including the importance of O{sub 4}{sup +} molecular levels.

  4. Functionalization of Hydrogen-free Diamond-like Carbon Films using Open-air Dielectric Barrier Discharge Atmospheric Plasma Treatments

    SciTech Connect

    Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Instituto de Materiales de Madrid, C.S.I.C., Cantoblanco, 28049 Madrid, Spain; Instituto de Quimica-Fisica"Rocasolano"C.S.I.C., 28006 Madrid, Spain; Mahasarakham University, Mahasarakham 44150, Thailand; CASTI, CNR-INFM Regional Laboratory, L'Aquila 67100, Italy; SUNY Upstate Medical University, Syracuse, NY 13210, USA; Endrino, Jose; Endrino, J. L.; Marco, J. F.; Poolcharuansin, P.; Phani, A.R.; Allen, M.; Albella, J. M.; Anders, A.

    2007-12-28

    A dielectric barrier discharge (DBD) technique has been employed to produce uniform atmospheric plasmas of He and N2 gas mixtures in open air in order to functionalize the surface of filtered-arc deposited hydrogen-free diamond-like carbon (DLC) films. XPS measurements were carried out on both untreated and He/N2 DBD plasma treated DLC surfaces. Chemical states of the C 1s and N 1s peaks were collected and used to characterize the surface bonds. Contact angle measurements were also used to record the short- and long-term variations in wettability of treated and untreated DLC. In addition, cell viability tests were performed to determine the influence of various He/N2 atmospheric plasma treatments on the attachment of osteoblast MC3T3 cells. Current evidence shows the feasibility of atmospheric plasmas in producing long-lasting variations in the surface bonding and surface energy of hydrogen-free DLC and consequently the potential for this technique in the functionalization of DLC coated devices.

  5. 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.

  6. Resonant- and avalanche-ionization amplification of laser-induced plasma in air

    SciTech Connect

    Wu, Yue; Zhang, Zhili; Jiang, Naibo; Roy, Sukesh; Gord, James R.

    2014-10-14

    Amplification of laser-induced plasma in air is demonstrated utilizing resonant laser ionization and avalanche ionization. Molecular oxygen in air is ionized by a low-energy laser pulse employing (2 + 1) resonance-enhanced multi-photon ionization (REMPI) to generate seed electrons. Subsequent avalanche ionization of molecular oxygen and nitrogen significantly amplifies the laser-induced plasma. In this plasma-amplification effect, three-body attachments to molecular oxygen dominate the electron-generation and -loss processes, while either nitrogen or argon acts as the third body with low electron affinity. Contour maps of the electron density within the plasma obtained in O₂/N₂ and O₂/Ar gas mixtures are provided to show relative degrees of plasma amplification with respect to gas pressure and to verify that the seed electrons generated by O₂ 2 + 1 REMPI are selectively amplified by avalanche ionization of molecular nitrogen in a relatively low-pressure condition (≤100 Torr). Such plasma amplification occurring in air could be useful in aerospace applications at high altitude.

  7. Resonant- and avalanche-ionization amplification of laser-induced plasma in air

    NASA Astrophysics Data System (ADS)

    Wu, Yue; Zhang, Zhili; Jiang, Naibo; Roy, Sukesh; Gord, James R.

    2014-10-01

    Amplification of laser-induced plasma in air is demonstrated utilizing resonant laser ionization and avalanche ionization. Molecular oxygen in air is ionized by a low-energy laser pulse employing (2 + 1) resonance-enhanced multi-photon ionization (REMPI) to generate seed electrons. Subsequent avalanche ionization of molecular oxygen and nitrogen significantly amplifies the laser-induced plasma. In this plasma-amplification effect, three-body attachments to molecular oxygen dominate the electron-generation and -loss processes, while either nitrogen or argon acts as the third body with low electron affinity. Contour maps of the electron density within the plasma obtained in O2/N2 and O2/Ar gas mixtures are provided to show relative degrees of plasma amplification with respect to gas pressure and to verify that the seed electrons generated by O2 2 + 1 REMPI are selectively amplified by avalanche ionization of molecular nitrogen in a relatively low-pressure condition (≤100 Torr). Such plasma amplification occurring in air could be useful in aerospace applications at high altitude.

  8. Evaluation of an air spinning process to produce tailored biosynthetic nanofibre scaffolds.

    PubMed

    Sabbatier, Gad; Abadie, Pierre; Dieval, Florence; Durand, Bernard; Laroche, Gaétan

    2014-02-01

    We optimised the working parameters of an innovative air spinning device to produce nanofibrous polymer scaffolds for tissue engineering applications. Scanning electron microscopy was performed on the fibre scaffolds which were then used to identify various scaffold morphologies based on the ratio of surface occupied by the polymer fibres on that covered by the entire polymer scaffold assembly. Scaffolds were then produced with the spinning experimental parameters, resulting in 90% of fibres in the overall polymer construct, and were subsequently used to perform a multiple linear regression analysis to highlight the relationship between nanofibre diameter and the air spinning parameters. Polymer solution concentration was deemed as the most significant parameter to control fibre diameter during the spinning process, despite interactions between experimental parameters. Based on these findings, viscosity measurements were performed to clarify the effect of the polymer solution property on scaffold morphology.

  9. Polymorphous silicon thin films produced in dusty plasmas: application to solar cells

    NASA Astrophysics Data System (ADS)

    Cabarrocas, Pere Roca i.; Chaâbane, N.; Kharchenko, A. V.; Tchakarov, S.

    2004-12-01

    We summarize our current understanding of the optimization of PIN solar cells produced by plasma enhanced chemical vapour deposition from silane hydrogen mixtures. To increase the deposition rate, the discharge is operated under plasma conditions close to powder formation, where silicon nanocrystals contribute to the deposition of so-called polymorphous silicon thin films. We show that the increase in deposition rate can be achieved via an accurate control of the plasma parameters. However, this also results in a highly defective interface in the solar cells due to the bombardment of the P-layer by positively charged nanocrystals during the deposition of the I-layer. We show that decreasing the ion energy by increasing the total pressure or by using silane helium mixtures allows us to increase both the deposition rate and the solar cells efficiency, as required for cost effective thin film photovoltaics.

  10. 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.

  11. Application of electrostatic Langmuir probe to atmospheric arc plasmas producing nanostructures

    SciTech Connect

    Shashurin, A.; Li, J.; Zhuang, T.; Keidar, M.; Beilis, I. I.

    2011-07-15

    The temporal evolution of a high pressure He arc producing nanotubes was considered and the Langmuir probe technique was applied for plasma parameter measurements. Two modes of arc were observed: cathodic arc where discharge is supported by erosion of cathode material and anodic arc which is supported by ablation of the anode packed with carbon and metallic catalysts in which carbon nanotubes are synthesized. Voltage-current (V-I) characteristics of single probes were measured and unusually low ratio of saturation current on positively biased probe to that on negatively biased of about 1-4 was observed. This effect was explained by increase of measured current at the negatively biased probe above the level of ion saturation current due to secondary electron emission from the probe surface. Since utilization of standard collisionless approach to determine plasma parameters from the measured V-I characteristic is not correct, the electron saturation current was used to estimate the plasma density.

  12. Plasma-wall interaction studies with optimized laser-produced jets

    SciTech Connect

    Renner, O.; Krousky, E.; Smid, M.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Pisarczyk, P.; Ullschmied, J.; Dalimier, E.

    2011-09-15

    The production of the laser-produced plasma jets at burnt-through low-Z foils was optimized by using three-frame interferometry. When striking secondary targets, these jets of energetic particles represent an efficient tool for the investigation of transient phenomena at surfaces of the plasma-exposed solids. Two sets of precisely measured x-ray spectroscopic data demonstrate diagnostic potential of the collimated jets in the plasma-wall interaction studies: Blue Doppler shifts of the Al jet self-emission visualize ion deceleration in the near-wall region. Local depressions found in Al Ly{gamma} profiles emitted from Al/Si(PMMA) targets indicate charge exchange between the Al XIII and fully stripped C ions.

  13. Enhanced filament ablation of metals based on plasma grating in air

    SciTech Connect

    Wang, Di; Liu, Fengjiang; Ding, Liangen; Yuan, Shuai; Zeng, Heping

    2015-09-15

    We demonstrate efficient ablation of metals with filamentary plasma grating generated by two intense blue femtosecond filaments and a third focused infrared pulse. This scheme leads to significant promotion of ablation efficiency on metal targets in air in comparison with single infrared or blue filament with equal pulse energy. The reason is that the blue plasma grating firstly provides stronger intensity and a higher density of background electrons, then the delayed infrared pulse accelerates local electrons inside the plasma grating. These two processes finally results in robustly increased electron density and highly ionized metallic atoms.

  14. Genetic effects of an air discharge plasma on Staphylococcus aureus at the gene transcription level

    NASA Astrophysics Data System (ADS)

    Xu, Zimu; Wei, Jun; Shen, Jie; Liu, Yuan; Ma, Ronghua; Zhang, Zelong; Qian, Shulou; Ma, Jie; Lan, Yan; Zhang, Hao; Zhao, Ying; Xia, Weidong; Sun, Qiang; Cheng, Cheng; Chu, Paul K.

    2015-05-01

    The dynamics of gene expression regulation (at transcription level) in Staphylococcus aureus after different doses of atmospheric-pressure room-temperature air plasma treatments are investigated by monitoring the quantitative real-time polymerase chain reaction. The plasma treatment influences the transcription of genes which are associated with several important bio-molecular processes related to the environmental stress resistance of the bacteria, including oxidative stress response, biofilm formation, antibiotics resistance, and DNA damage protection/repair. The reactive species generated by the plasma discharge in the gas phase and/or induced in the liquid phase may account for these gene expression changes.

  15. Optimally enhanced optical emission in laser-induced air plasma by femtosecond double-pulse

    SciTech Connect

    Chen, Anmin; Li, Suyu; Li, Shuchang; Jiang, Yuanfei; Ding, Dajun; Shao, Junfeng; Wang, Tingfeng; Huang, Xuri; Jin, Mingxing

    2013-10-15

    In laser-induced breakdown spectroscopy, a femtosecond double-pulse laser was used to induce air plasma. The plasma spectroscopy was observed to lead to significant increase of the intensity and reproducibility of the optical emission signal compared to femtosecond single-pulse laser. In particular, the optical emission intensity can be optimized by adjusting the delay time of femtosecond double-pulse. An appropriate pulse-to-pulse delay was selected, that was typically about 50 ps. This effect can be especially advantageous in the context of femtosecond laser-induced breakdown spectroscopy, plasma channel, and so on.

  16. Parabolic lithium mirror for a laser-driven hot plasma producing device

    DOEpatents

    Baird, James K.

    1979-06-19

    A hot plasma producing device is provided, wherein pellets, singly injected, of frozen fuel are each ignited with a plurality of pulsed laser beams. Ignition takes place within a void area in liquid lithium contained within a pressure vessel. The void in the liquid lithium is created by rotating the pressure vessel such that the free liquid surface of molten lithium therein forms a paraboloid of revolution. The paraboloid functions as a laser mirror with a reflectivity greater than 90%. A hot plasma is produced when each of the frozen deuterium-tritium pellets sequentially arrive at the paraboloid focus, at which time each pellet is illuminated by the plurality of pulsed lasers whose rays pass through circular annuli across the top of the paraboloid. The beams from the lasers are respectively directed by associated mirrors, or by means of a single conical mirror in another embodiment, and by the mirror-like paraboloid formed by the rotating liquid lithium onto the fuel pellet such that the optical flux reaching the pellet can be made to be uniform over 96% of the pellet surface area. The very hot plasma produced by the action of the lasers on the respective singly injected fuel pellets in turn produces a copious quantity of neutrons and X-rays such that the device has utility as a neutron source or as an x-ray source. In addition, the neutrons produced in the device may be utilized to produce tritium in a lithium blanket and is thus a mechanism for producing tritium.

  17. Interaction of high-power microwave with air breakdown plasma at low pressure

    NASA Astrophysics Data System (ADS)

    Zhao, Pengcheng; Guo, Lixin; Shu, Panpan

    2016-09-01

    The high-power microwave breakdown at the low air pressure (about 0.01 atm) is simulated numerically using the one-dimensional model coupling Maxwell's equations with plasma fluid equations. The accuracy of the model is validated by comparing the breakdown prediction with the experimental data. We find that a diffuse plasma with a stationary front profile forms due to the large electron diffusion. Most of the incident wave energy is absorbed and reflected by the plasma when the plasma front achieves a stationary profile. The front propagation velocity remains almost unchanged with time and increases when the incident wave amplitude increases or the incident wave frequency decreases. With the incident wave frequency increasing, the maximum density of the stationary plasma front increases, while the ratio of the reflected wave power to the incident wave power remains almost unchanged. At a higher incident wave amplitude, the maximum density and reflectance become large.

  18. K-shell spectroscopy of an independently diagnosed uniaxially expanding laser-produced aluminum plasma

    NASA Astrophysics Data System (ADS)

    Chambers, D. M.; Pinto, P. A.; Hawreliak, J.; Al'Miev, I. R.; Gouveia, A.; Sondhauss, P.; Wolfrum, E.; Wark, J. S.; Glenzer, S. H.; Lee, R. W.; Young, P. E.; Renner, O.; Marjoribanks, R. S.; Topping, S.

    2002-08-01

    We present detailed spectroscopic analysis of the primary K-shell emission lines from a uniaxially expanding laser-produced hydrogenic and heliumlike aluminum plasma. The spectroscopic measurements are found to be consistent with time-dependent hydrodynamic properties of the plasma, measured using Thomson scattering and shadowgraphy. The K-shell population kinetics code FLY with the measured hydrodynamic parameters is used to generate spectra that are compared to the experimental spectra. Excellent agreement is found between the measured and calculated spectra for a variety of experimental target widths employed to produce plasmas with different optical depths. The peak emission from the hydrogenic Lyman series is determined to be from a temporal and spatial region where the hydrodynamic parameters are essentially constant. This allows a single steady-state solution of FLY to be used to deduce the electron temperature and density, from the measured line ratios and linewidths, for comparison with the Thomson and shadowgraphy data. These measurements are found to agree well with time-dependent calculations, and provide further validation for the FLY calculations of the ionization and excitation balance for a K-shell aluminum plasma. We also discuss the possible application of this data as a benchmark for hydrodynamic simulations and ionization/excitation balance calculations.

  19. Laser ablation plasma-assisted stabilization of premixed methane/air flame

    NASA Astrophysics Data System (ADS)

    Li, Xiaohui; Yu, Yang; Peng, Jiangbo; Yu, Xin; Fan, Rongwei; Sun, Rui; Chen, Deying

    2016-01-01

    Laser ablation plasma has been applied to assist stabilization of premixed methane/air flames with a flow speed up to 15.3 m/s. The ablation plasma was generated using the 50 Hz, 1064 nm output of a Nd:YAG laser onto a tantalum slab. With the ablation plasma, the stabilization equivalence ratio has been extended to the fuel-leaner end and the blow off limits have been enhanced by from 3.6- to 14.8-folds for flames which can stabilize without the plasma. The laser pulse energy required for flameholding was reduced to 10 mJ, a 64 % reduction compared with that of gas breakdown plasma, which will ease the demand for high-power lasers for high-frequency plasma generation. The temporal evolutions of the flame kernels following the ablation plasma were investigated using the OH* chemiluminescence imaging approach, and the flame propagation speed ( v f) was measured from the flame kernel evolutions. With the ablation plasma, the v f with flow speed of 4.7-9.0 m/s and equivalence ratio of 1.4 has been enhanced from 0.175 m/s of laminar premixed methane/air flame to 2.79-4.52 and 1.59-5.46 m/s, respectively, in the early and late time following the ablation plasma. The increase in the combustion radical concentrations by the ablation plasma was thought to be responsible for the v f enhancement and the resulted flame stabilization.

  20. Characteristics of argon plasma waveguide produced by alumina capillary discharge for short wavelength laser application

    SciTech Connect

    Higashiguchi, Takeshi; Yugami, Noboru; Bobrova, Nadezhda; Sasorov, Pavel; Sakai, Shohei; Sentoku, Yasuhiko; Kodama, Ryosuke

    2012-05-01

    We have reported the argon (Ar) plasma waveguide produced in an alumina (Al{sub 2}O{sub 3}) capillary discharge and used to guide ultrashort laser pulses at intensities of the order of 10{sup 16} W/cm{sup 2}. The electron density in the plasma waveguide was measured to be 1x10{sup 18} cm{sup -3}, in agreement with one-dimensional magnetrohydrodynamic (MHD) simulations. The MHD code was also used to evaluate the degree of ionization of argon (Ar) in the preformed plasma waveguide. The maximum ion charge state of Ar{sup 3+} in capillary discharge was measured and obtained in the MHD simulations. The spectrum of the propagated laser pulse in the Ar plasma waveguide was not modified and was well reproduced by a particle-in-cell simulations under initial ion charge state of Ar{sup 3+} in the preformed plasma waveguide. The optimum timing for the laser pulse injection was around 150 ns after initiation of a discharge with a peak current of 200 A.

  1. Detailed energy distributions in laser-produced plasmas of solid gold and foam gold planar targets

    SciTech Connect

    Dong, Yunsong; Zhang, Lu; Yang, Jiamin; Shang, Wanli

    2013-12-15

    Foam gold was proposed to increase the laser to x-ray conversion efficiency due to its important applications. To understand the mechanism of x-ray enhancement, the detailed energy distributions and plasma profiles for laser-irradiated solid gold and foam gold targets were studied comparatively by hydrodynamic simulations using the code Multi-1D. It is confirmed that the radiation heat wave is subsonic for the normal solid gold target, while supersonic for the foam gold target. The shock wave, which is behind the supersonic radiation heat wave for the foam gold target, generates a plasma temperature gradient with high temperature near the shock wave front to produce an additional net outward radiation for enhancement of the x-ray emission. Much larger inward plasma velocity is also driven by the shock wave as an initial plasma velocity for the laser deposition and electron thermal conduct zone, which decreases the expanding plasma kinetic energy loss and helps to increase the x-ray radiation.

  2. Pressure-driven, resistive magnetohydrodynamic interchange instabilities in laser-produced high-energy-density plasmas

    SciTech Connect

    Li, C. K.; Frenje, J. A.; Petrasso, R. D.; Seguin, F. H.; Amendt, P. A.; Landen, O. L.; Town, R. P. J.; Betti, R.; Knauer, J. P.; Meyerhofer, D. D.; Soures, J. M.

    2009-07-15

    Recent experiments using proton backlighting of laser-foil interactions provide unique opportunities for studying magnetized plasma instabilities in laser-produced high-energy-density plasmas. Time-gated proton radiograph images indicate that the outer structure of a magnetic field entrained in a hemispherical plasma bubble becomes distinctly asymmetric after the laser turns off. It is shown that this asymmetry is a consequence of pressure-driven, resistive magnetohydrodynamic (MHD) interchange instabilities. In contrast to the predictions made by ideal MHD theory, the increasing plasma resistivity after laser turn-off allows for greater low-mode destabilization (m>1) from reduced stabilization by field-line bending. For laser-generated plasmas presented herein, a mode-number cutoff for stabilization of perturbations with m>{approx}[8{pi}{beta}(1+D{sub m}k{sub perpendicular}{sup 2}{gamma}{sub max}{sup -1})]{sup 1/2} is found in the linear growth regime. The growth is measured and is found to be in reasonable agreement with model predictions.

  3. Ion Flux Measurements in Electron Beam Produced Plasmas in Atomic and Molecular Gases

    NASA Astrophysics Data System (ADS)

    Walton, S. G.; Leonhardt, D.; Blackwell, D. D.; Murphy, D. P.; Fernsler, R. F.; Meger, R. A.

    2001-10-01

    In this presentation, mass- and time-resolved measurements of ion fluxes sampled from pulsed, electron beam-generated plasmas will be discussed. Previous works have shown that energetic electron beams are efficient at producing high-density plasmas (10^10-10^12 cm-3) with low electron temperatures (Te < 1.0 eV) over the volume of the beam. Outside the beam, the plasma density and electron temperature vary due, in part, to ion-neutral and electron-ion interactions. In molecular gases, electron-ion recombination plays a significant role while in atomic gases, ion-neutral interactions are important. These interactions also determine the temporal variations in the electron temperature and plasma density when the electron beam is pulsed. Temporally resolved ion flux and energy distributions at a grounded electrode surface located adjacent to pulsed plasmas in pure Ar, N_2, O_2, and their mixtures are discussed. Measurements are presented as a function of operating pressure, mixture ratio, and electron beam-electrode separation. The differences in the results for atomic and molecular gases will also be discussed and related to their respective gas-phase kinetics.

  4. Study of Plasma Treatment of Produced Water from Oil and Gas Exploration

    NASA Astrophysics Data System (ADS)

    Wright, Kamau

    Unconventional gas and hydraulic fracturing is helping to increase natural gas production, which is widely viewed in the U.S. as a key asset to bolstering a clean and energy-independent future. Safe and economical management and treatment of water produced during such processes remain of key importance. With the increase of hydrocarbon production and national shale gas production expected to increase threefold and account for nearly half of all natural gas produced by 2035, advanced water treatment and management processes must be investigated, to ensure water conservation and associated economic prudence. The state of the art of produced water treatment technologies is described including the efficacy of plasma to modulate the contents of such aqueous solutions, meeting target parameters and potentially enabling the operation of other treatment technologies. Among other effects, progress is presented on the enhancement of an arc-in-water system to remove bicarbonate ions and prevent the mineral fouling ability of water which causes formation of CaCO3 in heat exchangers and distillation units. Qualitative and quantitative treatment targets of produced water treatment are discussed. Experimental work is conducted to test theories and identify and reproduce favorable effects useful to treating wastewaters. Plasma arc-in-water systems demonstrated capability of producing bicarbonate-depleted wastewaters, with experiments with gas-field produced waters indicating that generation of H+ ions plays a greater role in bicarbonate ion removal than local heating. Tests showed abatement of bicarbonate ions from a range of 684--778 mg/L down to zero. Subsequent scaling/fouling tests with waters ranging from 0 to 500 mg/L bicarbonate ions, in the presence of high calcium ion concentrations, showed that scale thickness, as well as mass on a 1-kW heating element was an order of magnitude less for process water containing 100 mg/L bicarbonate ions compared to process water with 500

  5. The expansion velocities of laser-produced plasmas determined from extreme ultraviolet spectral line profiles

    NASA Technical Reports Server (NTRS)

    Feldman, U.; Doschek, G. A.; Behring, W. E.; Cohen, L.

    1977-01-01

    The expansion of laser-produced plasma is determined from the shapes of spectral lines of highly ionized iron emitted in the extreme ultraviolet. The plasmas were produced by focusing the pulse from a Nd:glass laser onto solid planar targets, and spectra were recorded with a high-resolution grazing-incidence spectrograph. From the Doppler broadening of lines of Fe XX and Fe XXI, expansion velocities of about 830 km/s were determined. The relative time-averaged ion abundances of Fe XVIII, Fe XIX, Fe XX, and Fe XXI are estimated for three different spectra. The abundances do not differ by more than a factor of 4 for any of the spectra.

  6. Astrophysics of magnetically collimated jets generated from laser-produced plasmas.

    PubMed

    Ciardi, A; Vinci, T; Fuchs, J; Albertazzi, B; Riconda, C; Pépin, H; Portugall, O

    2013-01-11

    The generation of astrophysically relevant jets, from magnetically collimated, laser-produced plasmas, is investigated through three-dimensional, magnetohydrodynamic simulations. We show that for laser intensities I∼10(12)-10(14) W cm(-2), a magnetic field in excess of ∼0.1  MG, can collimate the plasma plume into a prolate cavity bounded by a shock envelope with a standing conical shock at its tip, which recollimates the flow into a supermagnetosonic jet beam. This mechanism is equivalent to astrophysical models of hydrodynamic inertial collimation, where an isotropic wind is focused into a jet by a confining circumstellar toruslike envelope. The results suggest an alternative mechanism for a large-scale magnetic field to produce jets from wide-angle winds.

  7. High-quality electron beam from laser wake-field acceleration in laser produced plasma plumes

    SciTech Connect

    Sanyasi Rao, Bobbili; Moorti, Anand; Rathore, Ranjana; Ali Chakera, Juzer; Anant Naik, Prasad; Dass Gupta, Parshotam

    2013-06-10

    Generation of highly collimated ({theta}{sub div}{approx}10 mrad), quasi-monoenergetic electron beam with peak energy 12 MeV and charge {approx}50 pC has been experimentally demonstrated from self-guided laser wake-field acceleration (LWFA) in a plasma plume produced by laser ablation of solid nylon (C{sub 12}H{sub 22}N{sub 2}O{sub 2}){sub n} target. A 7 TW, 45 fs Ti:sapphire laser system was used for LWFA, and the plasma plume forming pulse was derived from the Nd:YAG pump laser of the same system. The results show that a reproducible, high quality electron beam could be produced from this scheme which is simple, low cost and has the capability for high repetition rate operation.

  8. Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas

    SciTech Connect

    Close, Sigrid; Lee, Nicolas; Johnson, Theresa; Goel, Ashish; Fletcher, Alexander; Linscott, Ivan; Strauss, David; Lauben, David; Srama, Ralf; Mocker, Anna; Bugiel, Sebastian

    2013-09-15

    Hypervelocity micro particles (mass < 1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (∼10{sup 28} m{sup −3}), but rapidly expand into the surrounding vacuum. We report the detection of radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity impacts of micro particles in ground-based experiments using micro particles that are 15 orders of magnitude less massive than previously observed. The EMP production is a stochastic process that is influenced by plasma turbulence such that the EMP detection rate that is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. In particular, impacts of the fastest micro particles occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. This new phenomenon may provide a source for unexplained RF measurements on spacecraft charged to high potentials.

  9. The development of a Krook model for nonlocal transport in laser produced plasmas I. Basic theory

    NASA Astrophysics Data System (ADS)

    Manheimer, Wallace; Colombant, Denis; Goncharov, Valeri

    2008-11-01

    We examine the Krook model as a means of quantifying the problem of nonlocal transport of electron energy in laser produced plasmas. The result is an expression for the nonlocal electron energy flux q. The roles of both flux limitation and preheat are clearly delineated. Furthermore, it develops a test for the validity of this model. This is a physics based ``first principles'' model that can be economically incorporated into a fluid simulation.

  10. The development of a Krook model for nonlocal transport in laser produced plasmas. I. Basic theory

    NASA Astrophysics Data System (ADS)

    Manheimer, Wallace; Colombant, Denis; Goncharov, Valeri

    2008-08-01

    This paper examines the Krook model as a means of quantifying the problem of nonlocal transport of electron energy in laser produced plasmas. The result is an expression for the nonlocal electron energy flux q. The roles of both flux limitation and preheat are clearly delineated. Furthermore, it develops a test for the validity of this model. This is a physics based, "first principles" model that can be economically incorporated into a fluid simulation.

  11. Emission from ionic cesium fluoride excimers excited by a laser-produced plasma

    NASA Astrophysics Data System (ADS)

    Kubodera, S.; Frey, L.; Wisoff, P. J.; Sauerbrey, R.

    1988-06-01

    Fluorescence was observed from the Cs(2+)F(-) state at 185 nm using a laser-produced plasma as the excitation source in a CsF heat pipe. The dependence of the ionic excimer emission on CsF vapor pressure and temporally resolved emission from the Cs(2+)F(-) is analyzed. It is found that the pressure dependence of the fluorescence is influenced by self-absorption in the CsF vapor.

  12. Experimental study of the ion emission from a 0. 53-. mu. m laser-produced plasma

    SciTech Connect

    Kieffer, J.C.; Quemener, Y.; Briand, J.; Gomes, A.; Adrian, V.; Dinguirard, J.P.; Armengaud, M.; Thoron, J.P.; Fournier, N.; El Tamer, M.

    1985-12-15

    Ion velocity distributions generated in a 0.53-..mu..m laser-produced plasma are studied with a Thomson parabola diagnostic at 5 x 10/sup 13/ W/cm/sup 2/. Ions are observed in a narrow energy range. However, for velocities >4 x 10/sup 5/ m/s the distribution dN/dV decreases exponentially and the temperatures deduced from these distributions are in good agreement with those given by x-ray emission.

  13. Urban air pollution produces up-regulation of myocardial inflammatory genes and dark chocolate provides cardioprotection.

    PubMed

    Villarreal-Calderon, Rodolfo; Reed, William; Palacios-Moreno, Juan; Keefe, Sheyla; Herritt, Lou; Brooks, Diane; Torres-Jardón, Ricardo; Calderón-Garcidueñas, Lilian

    2012-05-01

    Air pollution is a serious environmental problem. Elderly subjects show increased cardiac morbidity and mortality associated with air pollution exposure. Mexico City (MC) residents are chronically exposed to high concentrations of fine particulate matter (PM(2.5)) and PM-associated lipopolysaccharides (PM-LPS). To test the hypothesis that chronic exposure to urban pollution produces myocardial inflammation, female Balb-c mice age 4 weeks were exposed for 16 months to two distinctly different polluted areas within MC: southwest (SW) and northwest (NW). SW mice were given either no treatment or chocolate 2g/9.5 mg polyphenols/3 times per week. Results were compared to mice kept in clean air. Key inflammatory mediator genes: cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), and the LPS receptor CD14 (cluster of differentiation antigen 14) were measured by real-time polymerase chain reaction. Also explored were target NFκB (nuclear factor κB), oxidative stress and antioxidant defense genes. TNF-α, IL-6, and COX-2 were significantly increased in both NW and SWMC mice (p=0.0001). CD14 was up-regulated in SW mice in keeping with the high exposures to particulate matter associated endotoxin. Chocolate administration resulted in a significant down-regulation of TNF-α (p<0.0001), IL-6 (p=0.01), and IL-1β (p=0.02). The up-regulation of antioxidant enzymes and the down-regulation of potent oxidases, toll-like receptors, and pro-apoptotic signaling genes completed the protective profile. Exposure to air pollution produces up-regulation of inflammatory myocardial genes and endotoxin plays a key role in the inflammatory response. Regular consumption of dark chocolate may reduce myocardial inflammation and have cardioprotective properties in the setting of air pollution exposures. PMID:20932730

  14. Urban Air Pollution Produces Up-Regulation of Myocardial Inflammatory Genes and Dark Chocolate Provides Cardioprotection

    PubMed Central

    Villarreal-Calderon, Rodolfo; Reed, William; Palacios-Moreno, Juan; Keefe, Sheyla; Herritt, Lou; Brooks, Diane; Torres-Jardón, Ricardo; Calderón-Garcidueñas, Lilian

    2010-01-01

    Air pollution is a serious environmental problem. Elderly subjects show increased cardiac morbidity and mortality associated with air pollution exposure. Mexico City (MC) residents are chronically exposed to high concentrations of fine particulate matter (PM2.5) and PM-associated lipopolysaccharides (PM-LPS). To test the hypothesis that chronic exposure to urban pollution produces myocardial inflammation, female Balb-c mice age 4 weeks were exposed for 16 months to two distinctly different polluted areas within MC: Southwest (SW) and Northwest (NW). SW mice were given either no treatment or chocolate 2g/9.5 mg polyphenols/3 times per week. Results were compared to mice kept in clean air. Key inflammatory mediator genes: cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), and the LPS receptor CD14 (cluster of differentiation antigen 14) were measured by real time polymerase chain reaction. Also explored were target NFκB (Nuclear Factor κ B), oxidative stress and antioxidant defense genes. TNF-α, IL-6, and COX-2 were significantly increased in both NW and SWMC mice (p=0.0001). CD14 was up-regulated in SW mice in keeping with the high exposures to particulate matter associated endotoxin. Chocolate administration resulted in a significant down-regulation of TNF-α (p<0.0001), IL-6 (p=0.01), and IL-1β (p=0.02). The up-regulation of antioxidant enzymes and the down-regulation of potent oxidases, toll-like receptors, and pro-apoptotic signaling genes completed the protective profile. Exposure to air pollution produces up-regulation of inflammatory myocardial genes and endotoxin plays a key role in the inflammatory response. Regular consumption of dark chocolate may reduce myocardial inflammation and have cardioprotective properties in the setting of air pollution exposures. PMID:20932730

  15. Thermophysics Characterization of Multiply Ionized Air Plasma Absorption of Laser Radiation

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See; Rhodes, Robert; Turner, Jim (Technical Monitor)

    2002-01-01

    The impact of multiple ionization of air plasma on the inverse Bremsstrahlung absorption of laser radiation is investigated for air breathing laser propulsion. Thermochemical properties of multiply ionized air plasma species are computed for temperatures up to 200,000 deg K, using hydrogenic approximation of the electronic partition function; And those for neutral air molecules are also updated for temperatures up to 50,000 deg K, using available literature data. Three formulas for absorption are calculated and a general formula is recommended for multiple ionization absorption calculation. The plasma composition required for absorption calculation is obtained by increasing the degree of ionization sequentially, up to quadruple ionization, with a series of thermal equilibrium computations. The calculated second ionization absorption coefficient agrees reasonably well with that of available data. The importance of multiple ionization modeling is demonstrated with the finding that area under the quadruple ionization curve of absorption is found to be twice that of single ionization. The effort of this work is beneficial to the computational plasma aerodynamics modeling of laser lightcraft performance.

  16. Modified by air plasma polymer tack membranes as drainage material for antiglaucomatous operations

    NASA Astrophysics Data System (ADS)

    Ryazantseva, T. V.; Kravets, L. I.; Elinson, V. M.

    2014-06-01

    The morphological and clinical studies of poly(ethylene terephthalate) track membranes modified by air plasma as drainage materials for antiglaucomatous operations were performed. It was demonstrated their compatibility with eye tissues. Moreover, it was shown that a new drainage has a good lasting hypotensive effect and can be used as operation for refractory glaucoma surgery.

  17. Physics and applications of atmospheric non-thermal air plasma with reference to environment

    NASA Astrophysics Data System (ADS)

    Marode, E.; Djermoune, D.; Dessante, P.; Deniset, C.; Ségur, P.; Bastien, F.; Bourdon, A.; Laux, C.

    2009-12-01

    Since air is a natural part of our environment, special attention is given to the study of plasmas in air at atmospheric pressure and their applications. This fact promoted the study of electrical conduction in air-like mixtures, i.e. mixtures containing an electronegative gas component. If the ionization growth is not limited its temporal evolution leads to spark formation, i.e. a thermal plasma of several thousand kelvins in a quasi-local thermodynamic equilibrium state. But before reaching such a thermal state, a plasma sets up where the electrons increase their energy characterized by an electron temperature Te much higher than that of heavy species T or T+ for the ions. Since the plasma is no longer characterized by only one temperature T, it is said to be in a non-thermal plasma (NTP) state. Practical ways are listed to prevent electron ionization from going beyond the NTP states. Much understanding of such NTP may be gathered from the study of the simple paradigmatic case of a discharge induced between a sharp positively stressed point electrode facing a grounded negative plane electrode. Some physical properties will be gathered from such configurations and links underlined between these properties and some associated applications, mostly environmental. Aerosol filtration and electrostatic precipitators, pollution control by removal of hazardous species contained in flue gas exhaust, sterilization applications for medical purposes and triggering fuel combustion in vehicle motors are among such applications nowadays.

  18. Creating nanoporosity in silver nanocolumns by direct exposure to radio-frequency air plasma

    NASA Astrophysics Data System (ADS)

    El Mel, Abdel-Aziz; Stephant, Nicolas; Hamon, Jonathan; Thiry, Damien; Chauvin, Adrien; Chettab, Meriem; Gautron, Eric; Konstantinidis, Stephanos; Granier, Agnès; Tessier, Pierre-Yves

    2015-12-01

    Nanoporous materials are of great importance for a broad range of applications including catalysis, optical sensors and water filtration. Although several approaches already exist for the creation of nanoporous materials, the race for the development of versatile methods, more suitable for the nanoelectronics industry, is still ongoing. In this communication we report for the first time on the possibility of generating nanoporosity in silver nanocolumns using a dry approach based on the oxidation of silver by direct exposure to a commercially available radio-frequency air plasma. The silver nanocolumns are created by glancing angle deposition using magnetron sputtering of a silver target in pure argon plasma. We show that upon exposure to the rf air plasma, the nanocolumns transform from solid silver into nanoporous silver oxide. We further show that by tuning the plasma pressure and the exposure duration, the oxidation process can be finely adjusted allowing for precisely controlling the morphology and the nanoporosity of the silver oxide nanocolumns. The generation of porosity within the silver nanocolumns is explained according to a cracking-induced oxidation mechanism based on two repeated events occurring alternately during the oxidation process: (i) oxidation of silver upon exposure to the air plasma and (ii) generation of nanocracks and blisters within the oxide layer due to the high internal stress generated within the material during oxidation.

  19. Laser-induced plasma spectroscopy of hydrogen Balmer series in laboratory air.

    PubMed

    Swafford, Lauren D; Parigger, Christian G

    2014-01-01

    Stark-broadened emission profiles for the hydrogen alpha and beta Balmer series lines in plasma are measured to characterize electron density and temperature. Plasma is generated using a typical laser-induced breakdown spectroscopy (LIBS) arrangement that employs a focused Q-switched neodymium-doped yttrium aluminum garnet (Nd : YAG) laser, operating at the fundamental wavelength of 1064 nm. The temporal evolution of the hydrogen Balmer series lines is explored using LIBS. Spectra from the plasma are measured following laser-induced optical breakdown in laboratory air. The electron density is primarily inferred from the Stark-broadened experimental data collected at various time delays. Due to the presence of nitrogen and oxygen in air, the hydrogen alpha and beta lines become clearly discernible from background radiation for time delays of 0.4 and 1.4 μs, respectively.

  20. Laser-induced plasmas in ambient air for incoherent broadband cavity-enhanced absorption spectroscopy.

    PubMed

    Ruth, Albert A; Dixneuf, Sophie; Orphal, Johannes

    2015-03-01

    The emission from a laser-induced plasma in ambient air, generated by a high power femtosecond laser, was utilized as pulsed incoherent broadband light source in the center of a quasi-confocal high finesse cavity. The time dependent spectra of the light leaking from the cavity was compared with those of the laser-induced plasma emission without the cavity. It was found that the light emission was sustained by the cavity despite the initially large optical losses of the laser-induced plasma in the cavity. The light sustained by the cavity was used to measure part of the S(1) ← S(0) absorption spectrum of gaseous azulene at its vapour pressure at room temperature in ambient air as well as the strongly forbidden γ-band in molecular oxygen: b(1)Σ(g)(+)(ν'=2)←X(3)Σ(g)(-)(ν''=0). PMID:25836833

  1. ELM simulation experiments using transient heat and particle load produced by a magnetized coaxial plasma gun

    NASA Astrophysics Data System (ADS)

    Shoda, K.; Sakuma, I.; Iwamoto, D.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2011-10-01

    It is considered that thermal transient events such as type I edge-localized modes (ELMs) and disruptions will limit the lifetime of plasma-facing components (PFCs) in ITER. It is predicted that the heat load onto the PFCs during type I ELMs in ITER is 0.2-2MJ/m2 with pulse length of ~0.1-1ms. We have investigated interaction between transient heat and particle load and the PFCs by using a magnetized coaxial plasma gun (MCPG) at University of Hyogo. In the experiment, a pulsed plasma with duration of ~0.5ms, incident ion energy of ~30eV, and surface absorbed energy density of ~0.3-0.7MJ/m2 was produced by the MCPG. However, no melting occurred on a tungsten surface exposed to a single plasma pulse of ~0.7MJ/m2, while cracks clearly appeared at the edge part of the W surface. Thus, we have recently started to improve the performance of the MCPG in order to investigate melt layer dynamics of a tungsten surface such as vapor cloud formation. In the modified MCPG, the capacitor bank energy for the plasma discharge is increased from 24.5 kJ to 144 kJ. In the preliminary experiments, the plasmoid with duration of ~0.6 ms, incident ion energy of ~ 40 eV, and the surface absorbed energy density of ~2 MJ/m2 was successfully produced at the gun voltage of 6 kV.

  2. Microwave plasma-assisted ignition and flameholding in premixed ethylene/air mixtures

    NASA Astrophysics Data System (ADS)

    Fuh, Che A.; Wu, Wei; Wang, Chuji

    2016-07-01

    In this study, a 2.45 GHz microwave source and a surfatron were used, coupled with a T-shaped quartz combustor, to investigate the role of a nonthermal microwave argon plasma jet on the plasma-assisted ignition and flameholding of a premixed ethylene/air mixture. A modified U-shaped plot of the minimum plasma power required for ignition versus fuel equivalence ratio was obtained, whereby the plasma power required for plasma-assisted ignition decreased with increase in fuel equivalence ratios in the range 0.2-0.6, but for fuel equivalence ratios of 0.7 and above, the plasma power required for ignition remained fairly constant throughout. It was observed that leaner fuel/air mixtures were more sensitive to heat losses to the surrounding and this sensitivity decreased with increase in the fuel equivalence ratio. Comparison with results obtained from previous studies suggested that the mixing scheme between the plasma and the premixed fuel/air mixture and the energy density of the fuel used played an important role in influencing the minimum plasma power required for ignition with the effect being more pronounced for near stoichiometric to rich fuel equivalence ratios (0.7-1.4). Flame images obtained showed a dual layered flame with an inner white core and a bluish outer layer. The images also showed an increased degree of flameholding (tethering of the flame to the combustor orifice) with increase in plasma power. The concurrency of the dual peaks in the emission intensity profiles for OH(A), CH(A), C2(d), and the rotational temperature profiles obtained via optical emission spectroscopy along with the ground state OH(X) number density profiles in the flame using cavity ringdown spectroscopy led to the proposal that the mechanism of plasma-assisted flameholding in ethylene/air flames is predominantly radical dependent with the formation of an inner radical rich flame core which enhances the ignition and stabilization of the surrounding coflow.

  3. Microwave plasma-assisted ignition and flameholding in premixed ethylene/air mixtures

    NASA Astrophysics Data System (ADS)

    Fuh, Che A.; Wu, Wei; Wang, Chuji

    2016-07-01

    In this study, a 2.45 GHz microwave source and a surfatron were used, coupled with a T-shaped quartz combustor, to investigate the role of a nonthermal microwave argon plasma jet on the plasma-assisted ignition and flameholding of a premixed ethylene/air mixture. A modified U-shaped plot of the minimum plasma power required for ignition versus fuel equivalence ratio was obtained, whereby the plasma power required for plasma-assisted ignition decreased with increase in fuel equivalence ratios in the range 0.2–0.6, but for fuel equivalence ratios of 0.7 and above, the plasma power required for ignition remained fairly constant throughout. It was observed that leaner fuel/air mixtures were more sensitive to heat losses to the surrounding and this sensitivity decreased with increase in the fuel equivalence ratio. Comparison with results obtained from previous studies suggested that the mixing scheme between the plasma and the premixed fuel/air mixture and the energy density of the fuel used played an important role in influencing the minimum plasma power required for ignition with the effect being more pronounced for near stoichiometric to rich fuel equivalence ratios (0.7–1.4). Flame images obtained showed a dual layered flame with an inner white core and a bluish outer layer. The images also showed an increased degree of flameholding (tethering of the flame to the combustor orifice) with increase in plasma power. The concurrency of the dual peaks in the emission intensity profiles for OH(A), CH(A), C2(d), and the rotational temperature profiles obtained via optical emission spectroscopy along with the ground state OH(X) number density profiles in the flame using cavity ringdown spectroscopy led to the proposal that the mechanism of plasma-assisted flameholding in ethylene/air flames is predominantly radical dependent with the formation of an inner radical rich flame core which enhances the ignition and stabilization of the surrounding coflow.

  4. Experimental investigation of ultraviolet laser induced plasma density and temperature evolution in air

    SciTech Connect

    Thiyagarajan, Magesh; Scharer, John

    2008-07-01

    We present measurements and analysis of laser induced plasma neutral densities and temperatures in dry air by focusing 200 mJ, 10 MW high power, 193 nm ultraviolet ArF (argon fluoride) laser radiation to a 30 {mu}m radius spot size. We examine these properties that result from multiphoton and collisional cascade processes for pressures ranging from 40 Torr to 5 atm. A laser shadowgraphy diagnostic technique is used to obtain the plasma electron temperature just after the shock front and this is compared with optical emission spectroscopic measurements of nitrogen rotational and vibrational temperatures. Two-color laser interferometry is employed to measure time resolved spatial electron and neutral density decay in initial local thermodynamic equilibrium (LTE) and non-LTE conditions. The radiating species and thermodynamic characteristics of the plasma are analyzed by means of optical emission spectroscopy (OES) supported by SPECAIR, a special OES program for air constituent plasmas. Core plasma rotational and vibrational temperatures are obtained from the emission spectra from the N{sub 2}C-B(2+) transitions by matching the experimental spectrum results with the SPECAIR simulation results and the results are compared with the electron temperature just behind the shock wave. The plasma density decay measurements are compared with a simplified electron density decay model that illustrates the dominant three-and two-body recombination terms with good correlation.

  5. Experimental investigation of ultraviolet laser induced plasma density and temperature evolution in air

    NASA Astrophysics Data System (ADS)

    Thiyagarajan, Magesh; Scharer, John

    2008-07-01

    We present measurements and analysis of laser induced plasma neutral densities and temperatures in dry air by focusing 200 mJ, 10 MW high power, 193 nm ultraviolet ArF (argon fluoride) laser radiation to a 30 μm radius spot size. We examine these properties that result from multiphoton and collisional cascade processes for pressures ranging from 40 Torr to 5 atm. A laser shadowgraphy diagnostic technique is used to obtain the plasma electron temperature just after the shock front and this is compared with optical emission spectroscopic measurements of nitrogen rotational and vibrational temperatures. Two-color laser interferometry is employed to measure time resolved spatial electron and neutral density decay in initial local thermodynamic equilibrium (LTE) and non-LTE conditions. The radiating species and thermodynamic characteristics of the plasma are analyzed by means of optical emission spectroscopy (OES) supported by SPECAIR, a special OES program for air constituent plasmas. Core plasma rotational and vibrational temperatures are obtained from the emission spectra from the N2C-B(2+) transitions by matching the experimental spectrum results with the SPECAIR simulation results and the results are compared with the electron temperature just behind the shock wave. The plasma density decay measurements are compared with a simplified electron density decay model that illustrates the dominant three-and two-body recombination terms with good correlation.

  6. Strategies for emission reduction of air pollutants produced from a chemical plant.

    PubMed

    Lee, Byeong-Kyu; Cho, Sung-Woong

    2003-01-01

    Various air pollution control (APC) techniques were employed in order to reduce emissions of air pollutants produced from chemical plants, which have many different chemical production facilities. For an emission reduction of acid gases, this study employed a method to improve solubility of pollutants by decreasing the operating temperature of the scrubbers, increasing the surface area for effective contact of gas and liquid, and modifying processes in the acid scrubbers. To reduce emission of both amines and acid gases, pollutant gas components were first separated, then condensation and/or acid scrubbing, depending on the chemical and physical properties of pollutant components, were used. To reduce emission of solvents, condensation and activated carbon adsorption were employed. To reduce emission of a mixture gases containing acid gases and solvents, the mixed gases were passed into the first condenser, the acid scrubber, the second condenser, and the activated carbon adsorption tower in sequence. As a strategy to reduce emission of pollutants at the source, this study also employed the simple pollution prevention concept of modification of the previously operating APC control device. Finally, air emissions of pollutants produced from the chemical plants were much more reduced by applying proper APC methods, depending upon the types (physical or chemical properties) and the specific emission situations of pollutants. PMID:12447574

  7. Quadrupole distribution generated by a laser induced plasma (LIP) in air in earliest instants using pulses of 532 or 355 nm

    NASA Astrophysics Data System (ADS)

    Paulin-Fuentes, J. Mauricio; Sánchez-Aké, C.; Bredice, Fausto O.; Villagrán-Muniz, Mayo

    2015-07-01

    The self-generated electric and magnetic fields in laser induced plasmas (LIPs) in air during the first 40 ns are experimentally investigated using different electric, magnetic and optical techniques. To produce LIPs we used the second and third harmonics (532 and 355 nm) of a Nd:YAG nanosecond pulsed laser with a range of irradiance from {{10}11} to {{10}12} W \\text{c}{{\\text{m}}-2} . The variation in time of the electric field was detected using the tip of a coaxial cable, and the spontaneous magnetic field (SMF) was measured using a \\dot{B} probe. The spatial and temporal evolution of the plasma was studied using shadowgraphy and fast photography. It was observed that produced LIPs using pulses of 532 and 355 nm, generate plasmas of double core over the laser axis, while we observed that produced LIPs by pulses of 1064 nm are composed of a single core plasma. We found that the double-core plasmas have a quadrupole distribution of the charge, consisting of two oppositely directed dipoles which in turn correspond to each plasma core. The magnetic diagnostic showed an oscillating magnetic field azimuthal to the main axis of the double-plasma.

  8. Experimental study of the spectral characteristics of laser-induced air plasma

    SciTech Connect

    Lin Zhaoxiang; Wu Jinquan; Sun Fenglou; Gong Shunsheng

    2010-05-01

    The characteristics of laser-induced air, N2, and O2 plasma spectra are investigated spectroscopically. The study concentrates mainly on the temporal behavior of laser-induced plasma after breakdown. We used delayed spectra and spectra evolution for this study. Except for the general one-beam laser-induced breakdown experiment, a second laser beam was added to further probe the behavior of plasma during its decay. We report the experimental results of spectra composition, spectra time evolution, and spectra affected by a second laser beam. We determined that all the laser-induced air plasma spectra are from a continuous spectrum and some line spectra superposed on the continuous spectrum. The stronger short wavelength continuous spectrum is caused by bremsstrahlung radiation of electrons in the plasma, and the weaker long wavelength continuous spectrum is caused by electron and ion recombination. Line spectra originate from excited molecules, atoms, and their first-order ions, but no line spectra form higher-order ions. The results show that the temporal behavior of some spectra is a decay-rise-redecay pattern. With the two laser beam experiment we found that all the spectra intensities are enhanced by the second laser beam, but the response of various spectra to the delay of the second laser beam is quite different, in particular, the intensity increments of some spectra increase with the delay of the second laser beam. Some microscopic processes of laser-induced plasma obtained from the experimental results are discussed. These results are useful for a better understanding of some laser-induced air plasma related applications, such as laser-guided lightning and laser-induced breakdown spectroscopy.

  9. Decay of femtosecond laser-induced plasma filaments in air, nitrogen, and argon for atmospheric and subatmospheric pressures.

    PubMed

    Aleksandrov, N L; Bodrov, S B; Tsarev, M V; Murzanev, A A; Sergeev, Yu A; Malkov, Yu A; Stepanov, A N

    2016-07-01

    The temporal evolution of a plasma channel at the trail of a self-guided femtosecond laser pulse was studied experimentally and theoretically in air, nitrogen (with an admixture of ∼3% O_{2}), and argon in a wide range of gas pressures (from 2 to 760 Torr). Measurements by means of transverse optical interferometry and pulsed terahertz scattering techniques showed that plasma density in air and nitrogen at atmospheric pressure reduces by an order of magnitude within 3-4 ns and that the decay rate decreases with decreasing pressure. The argon plasma did not decay within several nanoseconds for pressures of 50-760 Torr. We extended our theoretical model previously applied for atmospheric pressure air plasma to explain the plasma decay in the gases under study and to show that allowance for plasma channel expansion affects plasma decay at low pressures. PMID:27575227

  10. Decay of femtosecond laser-induced plasma filaments in air, nitrogen, and argon for atmospheric and subatmospheric pressures

    NASA Astrophysics Data System (ADS)

    Aleksandrov, N. L.; Bodrov, S. B.; Tsarev, M. V.; Murzanev, A. A.; Sergeev, Yu. A.; Malkov, Yu. A.; Stepanov, A. N.

    2016-07-01

    The temporal evolution of a plasma channel at the trail of a self-guided femtosecond laser pulse was studied experimentally and theoretically in air, nitrogen (with an admixture of ˜3% O2), and argon in a wide range of gas pressures (from 2 to 760 Torr). Measurements by means of transverse optical interferometry and pulsed terahertz scattering techniques showed that plasma density in air and nitrogen at atmospheric pressure reduces by an order of magnitude within 3-4 ns and that the decay rate decreases with decreasing pressure. The argon plasma did not decay within several nanoseconds for pressures of 50-760 Torr. We extended our theoretical model previously applied for atmospheric pressure air plasma to explain the plasma decay in the gases under study and to show that allowance for plasma channel expansion affects plasma decay at low pressures.

  11. High-resolution X-ray focusing concave (elliptical) curved crystal spectrograph for laser-produced plasma

    NASA Astrophysics Data System (ADS)

    Xiao, Shali; Pan, Yingjun; Zhong, Xianxin; Xiong, Xiancai; Yang, Guohong; Liu, Zongli; Ding, Yongkun

    2004-08-01

    The X-ray spectrum emitted from laser-produced plasma contains plentiful information. X-ray spectrometer is a powerful tool for plasma diagnosis and studying the information and evolution of the plasma. X-ray concave (elliptical) curved crystals analyzer was designed and manufactured to investigate the properties of laser-produced plasma. The experiment was carried out on Mianyang Xingguang-II Facility and aimed at investigating the characteristics of a high density iron plasma. Experimental results using KAP, LIF, PET, and MICA curved crystal analyzers are described, and the spectra of Au, Ti laser-produced plasma are shown. The focusing crystal analyzer clearly gave an increase in sensitivity over a flat crystal.

  12. Distribution and mycotoxin-producing ability of some fungal isolates from the air

    NASA Astrophysics Data System (ADS)

    Cvetnić, Zdenka; Pepeljnjak, S.

    Research was carried out on presence and prevalence of common fungal air spores at locations in Croatia. The sampling method employed in the study was by exposure 350 of Petri agar plates to the air for 10 min. Approximately 3400 colonies were found and mould spores belonging to 22 fungal genera were identified. Cladosporium (44.7%), Penicillium (34.4%), Alternaria (26.3%), Aspergillus (21.6%) and Absidia (12.2%) were the most prevalent fungi encountered. Investigation of toxigenic potential of airborne fungi isolates of genera Aspergillus, Fusarium and Trichoderma showed 16.9% mycotoxin-producing strains. The production of aflatoxin B 1 by A. flavus sterigmatocystin by A. versicolor zearalenon and T-2 toxin by F. graminearum and diacetoscirpenol by strains of T. viride were obtained.

  13. 3-D simulations of magnetic reconnection in high-energy-density laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Fox, W.; Bhattacharjee, A.; Germaschewski, K.

    2012-10-01

    Magnetic reconnection has recently been observed and studied in high-energy-density, laser-produced plasmas, in a regime characterized by extremely high magnetic fields, high plasma beta and strong, supersonic plasma inflow. These experiments are interesting both for obtaining fundamental data on reconnection, and may also be relevant for inertial fusion, as this magnetic reconnection geometry, with multiple, colliding, magnetized plasma bubbles occurs naturally inside ICF hohlraums. Previous 2-d particle-in-cell reconnection simulations, with parameters and geometry relevant to the experiments, identified key ingredients for obtaining the very fast reconnection rates, namely two-fluid reconnection mediated by collisionless effects (the Hall current and electron pressure tensor), and strong flux pile-up of the inflowing magnetic field [1]. We present results from extending the previous simulations to 3-d, and discuss 3-d effects in the experiments, including instabilities in the reconnection layer, the topological skeleton of null-null lines, and field-generation from the Biermann battery effect. [4pt] [1] W. Fox, A. Bhattacharjee, and K. Germaschewski, PRL 106, 215003 (2011).

  14. Enhancements of extreme ultraviolet emission using prepulsed Sn laser-produced plasmas for advanced lithography applications

    SciTech Connect

    Freeman, J. R.; Harilal, S. S.; Hassanein, A.

    2011-10-15

    Laser-produced plasmas (LPP) from Sn targets are seriously considered to be the light source for extreme ultraviolet (EUV) next generation lithography, and optimization of such a source will lead to improved efficiency and reduced cost of ownership of the entire lithography system. We investigated the role of reheating a prepulsed plasma and its effect on EUV conversion efficiency (CE). A 6 ns, 1.06 {mu}m Nd:yttrium aluminum garnet laser was used to generate the initial plasma that was then reheated by a 40 ns, 10.6 {mu}m CO{sub 2} laser to generate enhanced EUV emission from a planar Sn target. The effects of prepulsed laser intensity and delay timings between the prepulsed and the pumping pulse were investigated to find the optimal pre-plasma conditions before the pumping pulse. The initial optimization of these parameters resulted in 25% increase in CE from the tin LPP. The cause of increased EUV emission was identified from EUV emission spectra and ion signal data.

  15. Process for producing plasma sprayed carbide-based coatings with minimal decarburization and near theoretical density

    SciTech Connect

    Lenling, W.J. ); Smith, M.F.; Henfling, J.A. )

    1990-01-01

    Plasma spray deposition of carbide/metal hardcoatings is difficult because complex chemical transformations can occur while spraying, especially in the presence of oxygen. A commercial plasma spray torch has been modified to simultaneously inject carbide powder and a metal alloy powder at two different locations in the plasma stream. Composite hardcoatings of tungsten carbide/cobalt with a nickel-base alloy matrix have been produce with this dual-injection spray process and compared to coatings sprayed with a conventional plasma spray process. X-ray diffraction revealed very little change in the carbide phase composition of dual-injection coatings as compared to the original composition of the carbide spray powder. Conversely, the conventionally sprayed coatings showed significant transformation of the WC phase to the less desirable W{sub 2}C phase, and secondary oxy- carbide phases were also clearly evident. Porosity in the dual- injection coatings was consistently less than 2%, as measured by image analysis of polished metallographic samples. Microhardness results for the dual injection coatings also compared very favorably with values for the conventional coatings. Preliminary results from an ongoing abrasive wear study indicate that the dual-injection coatings are more wear resistant than the conventional coatings, but further research is needed. 6 refs., 3 figs., 3 tabs.

  16. Modeling of laser produced plasma and z-pinch x-ray lasers

    SciTech Connect

    Dunn, J; Frati, M; Gonzales, J J; Kalashnikov, M P; Marconi, M C; Moreno, C H; Nickels, P V; Osterheld, A L; Rocca, J J; Sandner, W; Shlyaptsev, V N

    1999-02-07

    In this work we describe our theoretical activities in two directions of interest. First, we discuss progress in modeling laser produced plasmas mostly related to transient collisional excitation scheme experiments with Ne- and recently with Ni-like ions. Calculations related to the delay between laser pulses, transient gain duration and hybrid laser/capillary approach are described in more detail. Second, the capillary discharge plasma research, extended to wider range of currents and rise-times has been outlined. We have systematically evaluated the major plasma and atomic kinetic properties by comparing near- and far-field X-ray laser output with that for the capillary Argon X-ray laser operating under typical current values. Consistent with the experiment insight was obtained for the 469{angstrom} X-ray laser shadowgraphy experiments with very small kiloamp currents. At higher currents, as much as {approximately}200 kA we evaluated plasma temperature, density and compared x-ray source size and emitted spectra.

  17. First experiments probing the collision of parallel magnetic fields using laser-produced plasmas

    DOE PAGES

    Rosenberg, M. J.; Li, C. K.; Fox, W.; Igumenshchev, I.; Seguin, F. H.; Town, R. P.; Frenje, J. A.; Stoeckl, C.; Glebov, V.; Petrasso, R. D.

    2015-04-08

    Novel experiments to study the strongly-driven collision of parallel magnetic fields in β~10, laser-produced plasmas have been conducted using monoenergetic proton radiography. These experiments were designed to probe the process of magnetic flux pileup, which has been identified in prior laser-plasma experiments as a key physical mechanism in the reconnection of anti-parallel magnetic fields when the reconnection inflow is dominated by strong plasma flows. In the present experiments using colliding plasmas carrying parallel magnetic fields, the magnetic flux is found to be conserved and slightly compressed in the collision region. Two-dimensional (2D) particle-in-cell (PIC) simulations predict a stronger flux compressionmore » and amplification of the magnetic field strength, and this discrepancy is attributed to the three-dimensional (3D) collision geometry. Future experiments may drive a stronger collision and further explore flux pileup in the context of the strongly-driven interaction of magnetic fields.« less

  18. Streptococci biofilm decontamination on teeth by low-temperature air plasma of dc corona discharges

    NASA Astrophysics Data System (ADS)

    Kovalóvá, Z.; Zahoran, M.; Zahoranová, A.; Machala, Z.

    2014-06-01

    Non-thermal plasmas of atmospheric pressure air direct current corona discharges were investigated for potential applications in dental medicine. The objective of this ex vivo study was to apply cold plasmas for the decontamination of Streptococci biofilm grown on extracted human teeth, and to estimate their antimicrobial efficiency and the plasma's impact on the enamel and dentine of the treated tooth surfaces. The results show that both positive streamer and negative Trichel pulse coronas can reduce bacterial population in the biofilm by up to 3 logs in a 10 min exposure time. This bactericidal effect can be reached faster (within 5 min) by electrostatic spraying of water through the discharge onto the treated tooth surface. Examination of the tooth surface after plasma exposure by infrared spectroscopy and scanning electron microscopy did not show any significant alteration in the tooth material composition or the tooth surface structures.

  19. Surface cleaning of metals in air with a one atmosphere uniform glow discharge plasma

    SciTech Connect

    Roth, J.R.; Ku, Y.

    1995-12-31

    The authors report the use of active species generated in a one atmosphere uniform glow discharge plasma reactor with a parallel-plate configuration to clean the surface of as-received metal samples from the machine shop floor. The experimental arrangement used to expose the 7 by 10 cm metal samples is shown. The lower parallel-plate electrode is a flat copper plate 22 by 22 cm, covered by a 5mm thick pyrex sheet. The upper electrode is formed by the bare metal sample plate, with the side to be cleaned facing the plasma. To assure plasma uniformity between the electrodes, it was helpful to direct a flow of air on the edges of the plasma volume. The cleanliness of the metal samples was determined with the standard sessile water drop test.

  20. Characteristics of Low Power CH4/Air Atmospheric Pressure Plasma Jet

    NASA Astrophysics Data System (ADS)

    ZHANG, Jun; XIAO, Dezhi; FANG, Shidong; SHU, Xingsheng; ZUO, Xiao; CHENG, Cheng; MENG, Yuedong; WANG, Shouguo

    2015-03-01

    A low power atmospheric pressure plasma jet driven by a 24 kHz AC power source and operated with a CH4/air gas mixture has been investigated by optical emission spectrometer. The plasma parameters including the electron excitation temperature, vibrational temperature and rotational temperature of the plasma jet at different discharge powers are diagnosed based on the assumption that the kinetic energy of the species obeys the Boltzmann distribution. The electron density at different power is also investigated by Hβ Stark broadening. The results show that the plasma source works under non-equilibrium conditions. It is also found that the vibrational temperature and rotational temperature increase with discharge power, whereas the electron excitation temperature seems to have a downward trend. The electron density increases from 0.8 × 1021 m-3 to 1.1 × 1021 m-3 when the discharge power increases from 53 W to 94 W.

  1. 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.

  2. Surface modification of poly(ethylene terephthalate) fibers induced by radio frequency air plasma treatment

    NASA Astrophysics Data System (ADS)

    Riccardi, Claudia; Barni, Ruggero; Selli, Elena; Mazzone, Giovanni; Massafra, Maria Rosaria; Marcandalli, Bruno; Poletti, Giulio

    2003-04-01

    The surface chemical and physical modifications of poly(ethylene terephthalate) (PET) fibers induced by radiofrequency air plasma treatments were correlated with the characteristics of the discharge parameters and the chemical composition of the plasma itself, to identify the plasma-induced surface processes prevailing under different operating conditions. Treated polymer surfaces were characterized by water droplet absorption time measurements and XPS analysis, as a function of the aging time in different media, and by AFM analysis. They exhibited a remarkable increase in hydrophilicity, accompanied by extensive etching and by the implantation of both oxygen- and nitrogen-containing polar groups. Etching was mainly a consequence of ion bombardment, yielding low molecular weight, water soluble oxidation products, while surface chemical modifications were mainly due to the action of neutral species on the plasma-activated polymer surface.

  3. Kinetic effects and nonlinear heating in intense x-ray-laser-produced carbon plasmas.

    PubMed

    Sentoku, Y; Paraschiv, I; Royle, R; Mancini, R C; Johzaki, T

    2014-11-01

    The x-ray laser-matter interaction for a low-Z material, carbon, is studied with a particle-in-cell code that solves the photoionization and x-ray transport self-consistently. Photoionization is the dominant absorption mechanism and nonthermal photoelectrons are produced with energy near the x-ray photon energy. The photoelectrons ionize the target rapidly via collisional impact ionization and field ionization, producing a hot plasma column behind the laser pulse. The radial size of the heated region becomes larger than the laser spot size due to the kinetic nature of the photoelectrons. The plasma can have a temperature of more than 10 000 K (>1eV), an energy density greater than 10^{4} J/cm^{3}, an ion-ion Coulomb coupling parameter Γ≥1, and electron degeneracy Θ≥1, i.e., strongly coupled warm dense matter. By increasing the laser intensity, the plasma temperature rises nonlinearly from tens of eV to hundreds of eV, bringing it into the high energy density matter regime. The heating depth and temperature are also controllable by changing the photon energy of the incident laser light.

  4. Study of Laser Produced Plasma of Limiter of the Aditya Tokomak for Detection of Molecular Bands

    NASA Astrophysics Data System (ADS)

    Rai, Awadhesh Kumar

    2016-06-01

    The tokamak wall protection is one of the prime concerns, and for this purpose, limiters are used. Graphite is commonly used as a limiter material and first wall material for complete coverage of the internal vacuum vessel surfaces of the tokamak. From the past few years, we are working to identify and quantify the impurities deposited on the different part of Aditya Tokamak in collaboration with the Scientists at Institute of Plasma Research, Ahmedabad, India using Laser Induced Breakdown Spectroscopy (LIBS) [1-3]. Laser induced breakdown spectroscopy (LIBS) spectra of limiter of Aditya Tokamak have been recorded in the spectral range of 200-900 nm in open atmosphere. Along with atomic and ionic spectral lines of the constituent elements of the limiter (1-3), LIBS spectra also give the molecular bands. When a high power laser beam is focused on the sample, laser induced plasma is produced on its surface. In early stage of the plasma Back ground continuum is dominated due to free-free or free-bound emission. Just after few nanoseconds the light from the plasma is dominated by ionic emission. Atomic emission spectra is dominated from the laser induced plasma during the first few microsecond after an ablation pulse where as molecular spectra is generated later when the plasma further cools down. For this purpose the LIBS spectra has been recorded with varying gate delay and gate width. The spectra of the limiter show the presence of molecular bands of CN and C2. To get better signal to background ratios of the molecular bands, different experimental parameters like gate delay, gate width, collection angle and collection point (spatial analysis off the plasama) of the plasma have been optimized. Thus the present paper deals with the variation of spectral intensity of the molecular bands with different experimental parameters. Keywords: Limiter, Molecular bands, C2, CN. References: 1. Proof-of-concept experiment for On-line LIBS Analysis of Impurity Layer Deposited on

  5. Inactivation of Escherichia coli ATCC 11775 in fresh produce using atmospheric pressure cold plasma

    NASA Astrophysics Data System (ADS)

    Bermudez-Aguirre, Daniela; Wemlinger, Erik; Barbosa-Canovas, Gustavo; Pedrow, Patrick; Garcia-Perez, Manuel

    2011-10-01

    Food-borne outbreaks are associated with the presence of pathogenic bacteria in food products such as fresh produce. One of the target microorganisms is Escherichia coli which exhibits resistance to being inactivated with conventional disinfection methods for vegetables. Atmospheric pressure cold plasma (APCP) was tested to disinfect three vegetables with challenge surfaces, lettuce, carrots and tomatoes. The produce was inoculated with the bacteria to reach an initial microbial concentration of 107 cfu/g. Vegetables were initially exposed to the APCP discharges from a needle array at 5.7 kV RMS in argon, processing times of 0.5, 3 and 5 min. Initial results indicate that microbial decontamination is effective on the lettuce (1.2 log reduction) when compared with other vegetables. To claim disinfection, a 3 log reduction or more is needed, which makes APCP treatment very promising technology for decontamination of produce. We propose that with method refinements full disinfection can be achieved using APCP.

  6. Tin laser-produced plasma source modeling at 13.5 nm for extreme ultraviolet lithography

    SciTech Connect

    White, J.; O'Sullivan, G.; Zakharov, S.; Choi, P.; Zakharov, V.; Nishimura, H.; Fujioka, S.; Nishihara, K.

    2008-04-14

    Extreme ultraviolet lithography semiconductor manufacturing requires a 13.5 nm light source. Laser-produced plasma emission from Sn V-Sn XIV ions is one proposed industry solution. The effect of laser pulse width and spatial profile on conversion efficiency is analyzed over a range of power densities using a two-dimensional radiative magnetohydrodynamic code and compared to experiment using a 1.064 {mu}m, neodymium:yttrium aluminium garnet laser on a planar tin target. The calculated and experimental conversion efficiencies and the effects of self-absorption in the plasma edge are compared. Best agreement between theory and experiment is found for an 8.0 ns Gaussian pulse.

  7. Spectra of plasmas of Ru, Rh, Pd and Mo produced with nanosecond and picosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Lokasani, Ragava; Long, Elaine; Sheridan, Paul; Hayden, Patrick; O'Reilly, Fergal; Dunne, Padraig; Endo, Akira; Limpouch, Jiri; O'Sullivan, Gerry

    2015-05-01

    This paper describes the extreme ultraviolet and soft x-ray emission recorded in the 2-12 nm region from Mo, Ru, Rh and Pd ions present in the laser produced plasmas. The spectra were found to be dominated by 3p-3d transitions in the 5-8 nm region, which shift slowly to shorter wavelengths with the increasing atomic number, and by 3d-4p and 3d-4f transitions at shorter wavelengths. These transitions, in a number of neighbouring ion stages, were distinguished by comparison with Cowan code calculations and previously reported data. The experimental results show that strong emission can be observed at the 6.X nm region for Ru, Rh and Pd plasmas.

  8. Correlation between laser absorption and radiation conversion efficiency in laser produced tin plasma

    SciTech Connect

    Matsukuma, Hiraku Hosoda, Tatsuya; Fujioka, Shinsuke; Nishimura, Hiroaki; Sunahara, Atsushi; Yanagida, Tatsuya; Tomuro, Hiroaki; Kouge, Kouichiro; Kodama, Takeshi

    2015-09-21

    The correlation between the laser absorption and the conversion efficiency (CE) for 13.5 nm extreme ultraviolet (EUV) light in a laser-produced tin plasma was investigated. The absorption rate α and the CE were measured simultaneously for a laser-pre-formed low-density tin target as a function of the time delay between the pre-pulse and the main laser pulse. A clear and positive correlation between α and CE was found with increasing delay time; however, the CE decreases rapidly at longer delay times. This result is partly attributed to a reduction in the absorption rate, but is mainly attributed to the self-absorption of EUV light in excessively long-scale plasmas.

  9. Fusion reactions initiated by laser-accelerated particle beams in a laser-produced plasma

    NASA Astrophysics Data System (ADS)

    Labaune, C.; Baccou, C.; Depierreux, S.; Goyon, C.; Loisel, G.; Yahia, V.; Rafelski, J.

    2013-10-01

    The advent of high-intensity-pulsed laser technology enables the generation of extreme states of matter under conditions that are far from thermal equilibrium. This in turn could enable different approaches to generating energy from nuclear fusion. Relaxing the equilibrium requirement could widen the range of isotopes used in fusion fuels permitting cleaner and less hazardous reactions that do not produce high-energy neutrons. Here we propose and implement a means to drive fusion reactions between protons and boron-11 nuclei by colliding a laser-accelerated proton beam with a laser-generated boron plasma. We report proton-boron reaction rates that are orders of magnitude higher than those reported previously. Beyond fusion, our approach demonstrates a new means for exploring low-energy nuclear reactions such as those that occur in astrophysical plasmas and related environments.

  10. Velocity distribution function of electrons plasma produced by high power laser pulse interacting aluminum target

    NASA Astrophysics Data System (ADS)

    Mahdieh, M. H.; Razi, E. M.

    2010-09-01

    This paper presents the experimental results of studying the distribution function of electrons plasma produced by irradiating aluminum target by nanosecond pulsed laser in vacuum. The laser beam was provided by second harmonic of a Q-switched Nd:YAG pulsed laser with ~10 nsec pulse duration and energy of 70 mJ. A home made Faraday cup was used for detecting the current signal. From analyzing the time of flight (TOF) experimental distribution function was determined. Comparing the experimental distribution function with Maxwell-Boltzamnn and effusion distribution functions, the electron temperature was estimated. From the experimental results, the velocity of maximum electron flux was determined. In this study the influence of the probe position and biasing voltage was investigated. The results show that the velocity of maximum electron flux and associated temperature rises with distance from the target surface. The results also show that effusion distribution function is more appropriate for modeling such plasma.

  11. Development of a Time-resolved Soft X-ray Spectrometer for Laser Produced Plasma Experiments

    SciTech Connect

    Cone, K V; Dunn, J; Schneider, M B; Baldis, H A; Brown, G V; Emig, J; James, D L; May, M J; Park, J; Shepherd, R; Widmann, K

    2010-05-12

    A 2400 line/mm variable spaced grating spectrometer (VSG) has been used to measure soft x-ray emission (8-22 {angstrom}) from laser-produced plasma experiments at Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (COMET) Laser Facility. The spectrometer was coupled to a Kentech x-ray streak camera to study the temporal evolution of soft x-rays emitted from the back of mylar and copper foils irradiated at 10{sup 15} W/cm{sup 2}. The instrument demonstrated a resolving power of {approx} 120 at 19 {angstrom} with a time resolution of 31 ps. The time-resolved copper emission spectrum was consistent with a photodiode monitoring the laser temporal pulse shape and indicated that the soft x-ray emission follows the laser heating of the target. The time and spectral resolution of this diagnostic make it useful for studies of high temperature plasmas.

  12. Non-Spitzer heat flow in a steadily ablating laser-produced plasma

    SciTech Connect

    Bell, A.R.

    1985-06-01

    Electron energy transport in a laser-produced ablating plasma is modeled by the Vlasov--Fokker--Planck equation for electrons and the fluid equations for cold ions. These equations are solved using approximations which maintain good accuracy but allow faster computational solution than was previously possible. It is found that the spatial profiles for temperature and density in planar geometry differ very little from those calculated from the Spitzer conductivity. At high laser intensities, the plasma flow diverges as it flows away from the solid target and the effects of nonplanar flow are important. This is modeled by the adoption of spherical geometry, and it is found that the Spitzer conductivity breaks down and the temperature and density profiles differ significantly from those calculated using the Spitzer conductivity.

  13. Electron energy transport in ion waves and its relevance to laser-produced plasmas

    SciTech Connect

    Bell, A.R.

    1983-01-01

    Electron energy transport in plasmas is examined in the context of ion waves which are intermediate between collisionless isothermal ion acoustic waves and collisional adiabatic sound waves. The conductivity is found to be much less than the Spitzer-Haerm result for wavelengths less than 1000 electron mean free paths. This is expected to be relevant to laser-produced ablating plasmas in which the temperature can vary considerably over a distance of 10 to 100 mean free paths. The reduction in conductivity is independent of the wave amplitude thus differing from the reduction due to saturation found recently by numerical solution of the Fokker--Planck equation. At short wavelengths the heat flow approaches an upper limit which depends on the phase velocity of the wave. Diffusive ion wave damping is strong over a large range of wavelengths.

  14. Fusion reactions initiated by laser-accelerated particle beams in a laser-produced plasma.

    PubMed

    Labaune, C; Baccou, C; Depierreux, S; Goyon, C; Loisel, G; Yahia, V; Rafelski, J

    2013-01-01

    The advent of high-intensity-pulsed laser technology enables the generation of extreme states of matter under conditions that are far from thermal equilibrium. This in turn could enable different approaches to generating energy from nuclear fusion. Relaxing the equilibrium requirement could widen the range of isotopes used in fusion fuels permitting cleaner and less hazardous reactions that do not produce high-energy neutrons. Here we propose and implement a means to drive fusion reactions between protons and boron-11 nuclei by colliding a laser-accelerated proton beam with a laser-generated boron plasma. We report proton-boron reaction rates that are orders of magnitude higher than those reported previously. Beyond fusion, our approach demonstrates a new means for exploring low-energy nuclear reactions such as those that occur in astrophysical plasmas and related environments. PMID:24104859

  15. Investigation of nanoparticle formation in a plasma produced by femtosecond laser ablation of gold

    SciTech Connect

    Spiga, P.; Hermann, J.; Itina, T.; Grojo, D.; Neamtu, D.; Pailharey, D.; Marine, W.

    2005-10-31

    The formation of nanoparticles in a plasma produced by the interaction of ultrashort laser pulses with gold has been investigated. Three different experimental techniques were employed. (i) The plume expansion was characterized using fast imaging with the aid of an intensified charge-coupled device. (ii) The plasma composition was analyzed using time- and space-resolved optical emission spectroscopy. (iii) The ablated material was deposited on mica substrates and analyzed by means of atomic force microscopy. As a result, the size-distribution and the overall number of nanoparticles were determined as a function of the laser energy density incident on the target surface. The detection of particles with sizes in the nanometer range supports theoretical modeling according to which phase explosion is the dominant mechanism of metal ablation by ultrashort laser pulses.

  16. Optical pyrometer system for collisionless shock experiments in high-power laser-produced plasmas.

    PubMed

    Morita, T; Sakawa, Y; Kuramitsu, Y; Dono, S; Ide, T; Shibata, S; Aoki, H; Tanji, H; Sano, T; Shiroshita, A; Waugh, J N; Gregory, C D; Woolsey, N C; Takabe, H

    2012-10-01

    A temporally and spatially resolved optical pyrometer system has been fielded on Gekko XII experiments. The system is based on the self-emission measurements with a gated optical imager (GOI) and a streaked optical pyrometer (SOP). Both detectors measure the intensity of the self-emission from laser-produced plasmas at the wavelength of 450 nm with a bandpass filter with a width of ~10 nm in FWHM. The measurements were calibrated with different methods, and both results agreed with each other within 30% as previously reported [T. Morita et al., Astrophys. Space Sci. 336, 283 (2011)]. As a tool for measuring the properties of low-density plasmas, the system is applicable for the measurements of the electron temperature and density in collisionless shock experiments [Y. Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011)]. PMID:23126856

  17. Optical pyrometer system for collisionless shock experiments in high-power laser-produced plasmas

    SciTech Connect

    Morita, T.; Sakawa, Y.; Kuramitsu, Y.; Sano, T.; Takabe, H.; Dono, S.; Ide, T.; Tanji, H.; Shiroshita, A.; Shibata, S.; Aoki, H.; Waugh, J. N.; Woolsey, N. C.; Gregory, C. D.

    2012-10-15

    A temporally and spatially resolved optical pyrometer system has been fielded on Gekko XII experiments. The system is based on the self-emission measurements with a gated optical imager (GOI) and a streaked optical pyrometer (SOP). Both detectors measure the intensity of the self-emission from laser-produced plasmas at the wavelength of 450 nm with a bandpass filter with a width of {approx}10 nm in FWHM. The measurements were calibrated with different methods, and both results agreed with each other within 30% as previously reported [T. Morita et al., Astrophys. Space Sci. 336, 283 (2011)]. As a tool for measuring the properties of low-density plasmas, the system is applicable for the measurements of the electron temperature and density in collisionless shock experiments [Y. Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011)].

  18. Physicochemical processes in the indirect interaction between surface air plasma and deionized water

    NASA Astrophysics Data System (ADS)

    Liu, Z. C.; Liu, D. X.; Chen, C.; Li, D.; Yang, A. J.; Rong, M. Z.; Chen, H. L.; Kong, M. G.

    2015-12-01

    One of the most central scientific questions for plasma applications in healthcare and environmental remediation is the chemical identity and the dose profile of plasma-induced reactive oxygen and nitrogen species (ROS/RNS) that can act on an object inside a liquid. A logical focus is on aqueous physicochemical processes near a sample with a direct link to their upstream gaseous processes in the plasma region and a separation gap from the liquid bulk. Here, a system-level modeling framework is developed for indirect interactions of surface air plasma and a deionized water bulk and its predictions are found to be in good agreement with the measurement of gas-phase ozone and aqueous long-living ROS/RNS concentrations. The plasma region is described with a global model, whereas the air gap and the liquid region are simulated with a 1D fluid model. All three regions are treated as one integrated entity and computed simultaneously. With experimental validation, the system-level modeling shows that the dominant aqueous ROS/RNS are long-living species (e.g. H2O2 aq, O3 aq, nitrite/nitrate, H+ aq). While most short-living gaseous species could hardly survive their passage to the liquid, aqueous short-living ROS/RNS are generated in situ through reactions among long-living plasma species and with water molecules. This plasma-mediated remote production of aqueous ROS/RNS is important for the abundance of aqueous HO2 aq, HO3 aq, OHaq and \\text{O}2- aq as well as NO2 aq and NO3 aq. Aqueous plasma chemistry offers a novel and significant pathway to activate a given biological outcome, as exemplified here for bacterial deactivation in plasma-activated water. Additional factors that may synergistically broaden the usefulness of aqueous plasma chemistry include an electric field by aqueous ions and liquid acidification. The system-modeling framework will be useful in assisting designs and analyses of future investigations of plasma-liquid and plasma-cell interactions.

  19. Hydrogen Balmer Series Self-Absorption Measurement in Laser-Induced Air Plasma

    NASA Astrophysics Data System (ADS)

    Gautam, Ghaneshwar; Parigger, Christian

    2015-05-01

    In experimental studies of laser-induced plasma, we use focused Nd:YAG laser radiation to generate optical breakdown in laboratory air. A Czerny-Turner type spectrometer and an ICCD camera are utilized to record spatially and temporally resolved spectra. Time-resolved spectroscopy methods are employed to record plasma dynamics for various time delays in the range of 0.300 microsecond to typically 10 microsecond after plasma initiation. Early plasma emission spectra reveal hydrogen alpha and ionized nitrogen lines for time delays larger than 0.3 microsecond, the hydrogen beta line emerges from the free-electron background radiation later in the plasma decay for time delays in excess of 1 microsecond. The self-absorption analyses include comparisons of recorded data without and with the use of a doubling mirror. The extent of self-absorption of the hydrogen Balmer series is investigated for various time delays from plasma generation. There are indications of self-absorption of hydrogen alpha by comparison with ionized nitrogen lines at a time delay of 0.3 microsecond. For subsequent time delays, self-absorption effects on line-widths are hardly noticeable, despite the fact of the apparent line-shape distortions. Of interest are comparisons of inferred electron densities from hydrogen alpha and hydrogen beta lines as the plasma decays, including assessments of spatial variation of electron density.

  20. Microwave interferometry of laser induced air plasmas formed by short laser pulses

    SciTech Connect

    Jungwirth, P.W.

    1993-08-01

    Applications for the interaction of laser induced plasmas with electromagnetic probes requires time varying complex conductivity data for specific laser/electromagnetic probe geometries. Applications for this data include plasma switching (Q switching) and the study of ionization fronts. The plasmas were created in laboratory air by 100 ps laser pulses at a wavelength of 1 {mu}m. A long focal length lens focused the laser pulse into WR90 (X band) rectangular waveguide. Two different laser beam/electromagnetic probe geometries were investigated. For the longitudinal geometry, the laser pulse and the microwave counterpropagated inside the waveguide. For the transverse geometry, the laser created a plasma ``post`` inside the waveguide. The effects of the laser beam deliberately hitting the waveguide were also investigated. Each geometry exhibits its own characteristics. This research project focused on the longitudinal geometry. Since the laser beam intensity varies inside the waveguide, the charge distribution inside the waveguide also varies. A 10 GHz CW microwave probe traveled through the laser induced plasma. From the magnitude and phase of the microwave probe, a spatially integrated complex conductivity was calculated. No measurements of the temporal or spatial variation of the laser induced plasma were made. For the ``plasma post,`` the electron density is more uniform.

  1. Non-Thermal Ignition of Hydrocarbon-Air Mixtures by Nonequilibrium Plasmas

    NASA Astrophysics Data System (ADS)

    Chintala, Naveen; Bao, Ainan; Lou, Guofeng; Rich, J. William; Lempert, Walter; Adamovich, Igor

    2004-09-01

    The paper presents results of nonequilibrium RF plasma assisted ignition and combustion experiments in premixed methane-air, ethylene-air, and CO-air flows. The results show that large volume ignition of these mixtures by a uniform, diffuse RF plasma can be achieved at high flow velocities (up to u=25 m/s) and low pressures (P=60-130 torr), as compared to either a spark discharge or a DC arc discharge. FT-IR measurements show that ignition occurs at temperatures below that of equilibrium autoignition by as much as 350o C. Spontaneous emission in the discharge detected presence of radical species such as CN, CH, C2, and OH, as well as O and H atoms. CO2 emission was also detected in the flame downstream of the RF plasma. FTIR absorption of the combustion products shows that up to 80burned in ethylene-air mixtures and 50mixtures. Further experiments at higher test section flow velocities and higher RF discharge powers are underway.

  2. Plasma produced by impacts of fast dust particles on a thin film

    NASA Technical Reports Server (NTRS)

    Auer, Siegfried

    1994-01-01

    The thin-film impact plasma detector was pioneered by Berg for detecting small cosmic dust particles and measuring their approximate velocities in a time-of-flight configuration. While Berg's device was highly successful in establishing the flux of interplanetary dust, the accuracy of measuring the velocities of individual particles was a moderate 18 percent in magnitude and 27 degrees in angle. A much greater accuracy of less than or equal to 1 percent in determining the velocity components appears desirable in order to associate a particle with its parent body. In order to meet that need, research was initiated to determine if a thin-film detector can be designed to provide such accurate velocity measurements. Previous laboratory investigations of the impact plasma uncovered two difficulties: (1) solid or liquid spray is ejected from a primary impact crater and strikes neighboring walls where it produces secondary impact craters and plasma clouds; as a result, both quantity and time of detection of the plasma can vary significantly with the experiment configuration. Particles from an accelerator rarely have speeds v greater than or equal to 10-15 km/s, while cosmic dust particles typically impact at v = 10-72 km/s. The purpose of the tests discussed in this paper was to resolve the two difficulties mentioned. That is, the experiment configuration was designed to reduce the contribution of plasma from secondary impacts. In addition, most particles with v less than or equal to 25 km/s and all particles with v less than or equal to 10 km/s were eliminated from the beam.

  3. Air-water ‘tornado’-type microwave plasmas applied for sugarcane biomass treatment

    NASA Astrophysics Data System (ADS)

    Bundaleska, N.; Tatarova, E.; Dias, F. M.; Lino da Silva, M.; Ferreira, C. M.; Amorim, J.

    2014-02-01

    The production of cellulosic ethanol from sugarcane biomass is an attractive alternative to the use of fossil fuels. Pretreatment is needed to separate the cellulosic material, which is packed with hemicellulose and lignin in cell wall of sugarcane biomass. A microwave ‘tornado’-type air-water plasma source operating at 2.45 GHz and atmospheric pressure has been applied for this purpose. Samples of dry and wet biomass (˜2 g) have been exposed to the late afterglow plasma stream. The experiments demonstrate that the air-water highly reactive plasma environment provides a number of long-lived active species able to destroy the cellulosic wrapping. Scanning electron microscopy has been applied to analyse the morphological changes occurring due to plasma treatment. The effluent gas streams have been analysed by Fourier-transform infrared spectroscopy (FT-IR). Optical emission spectroscopy and FT-IR have been applied to determine the gas temperature in the discharge and late afterglow plasma zones, respectively. The optimal range of the operational parameters is discussed along with the main active species involved in the treatment process. Synergistic effects can result from the action of singlet O2(a 1Δg) oxygen, NO2, nitrous acid HNO2 and OH hydroxyl radical.

  4. Cold atmospheric air plasma sterilization against spores and other microorganisms of clinical interest.

    PubMed

    Klämpfl, Tobias G; Isbary, Georg; Shimizu, Tetsuji; Li, Yang-Fang; Zimmermann, Julia L; Stolz, Wilhelm; Schlegel, Jürgen; Morfill, Gregor E; Schmidt, Hans-Ulrich

    2012-08-01

    Physical cold atmospheric surface microdischarge (SMD) plasma operating in ambient air has promising properties for the sterilization of sensitive medical devices where conventional methods are not applicable. Furthermore, SMD plasma could revolutionize the field of disinfection at health care facilities. The antimicrobial effects on Gram-negative and Gram-positive bacteria of clinical relevance, as well as the fungus Candida albicans, were tested. Thirty seconds of plasma treatment led to a 4 to 6 log(10) CFU reduction on agar plates. C. albicans was the hardest to inactivate. The sterilizing effect on standard bioindicators (bacterial endospores) was evaluated on dry test specimens that were wrapped in Tyvek coupons. The experimental D(23)(°)(C) values for Bacillus subtilis, Bacillus pumilus, Bacillus atrophaeus, and Geobacillus stearothermophilus were determined as 0.3 min, 0.5 min, 0.6 min, and 0.9 min, respectively. These decimal reduction times (D values) are distinctly lower than D values obtained with other reference methods. Importantly, the high inactivation rate was independent of the material of the test specimen. Possible inactivation mechanisms for relevant microorganisms are briefly discussed, emphasizing the important role of neutral reactive plasma species and pointing to recent diagnostic methods that will contribute to a better understanding of the strong biocidal effect of SMD air plasma.

  5. 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.

  6. Cold Atmospheric Air Plasma Sterilization against Spores and Other Microorganisms of Clinical Interest

    PubMed Central

    Isbary, Georg; Shimizu, Tetsuji; Li, Yang-Fang; Zimmermann, Julia L.; Stolz, Wilhelm; Schlegel, Jürgen; Morfill, Gregor E.; Schmidt, Hans-Ulrich

    2012-01-01

    Physical cold atmospheric surface microdischarge (SMD) plasma operating in ambient air has promising properties for the sterilization of sensitive medical devices where conventional methods are not applicable. Furthermore, SMD plasma could revolutionize the field of disinfection at health care facilities. The antimicrobial effects on Gram-negative and Gram-positive bacteria of clinical relevance, as well as the fungus Candida albicans, were tested. Thirty seconds of plasma treatment led to a 4 to 6 log10 CFU reduction on agar plates. C. albicans was the hardest to inactivate. The sterilizing effect on standard bioindicators (bacterial endospores) was evaluated on dry test specimens that were wrapped in Tyvek coupons. The experimental D23°C values for Bacillus subtilis, Bacillus pumilus, Bacillus atrophaeus, and Geobacillus stearothermophilus were determined as 0.3 min, 0.5 min, 0.6 min, and 0.9 min, respectively. These decimal reduction times (D values) are distinctly lower than D values obtained with other reference methods. Importantly, the high inactivation rate was independent of the material of the test specimen. Possible inactivation mechanisms for relevant microorganisms are briefly discussed, emphasizing the important role of neutral reactive plasma species and pointing to recent diagnostic methods that will contribute to a better understanding of the strong biocidal effect of SMD air plasma. PMID:22582068

  7. Two-dimensional calculations of a continuous optical discharge in atmospheric air flow (optical plasma generator)

    NASA Astrophysics Data System (ADS)

    Raizer, Iu. P.; Silant'ev, A. Iu.; Surzhikov, S. T.

    1987-06-01

    Two-dimensional gasdynamic processes in a continuous optical discharge in subsonic flow of atmospheric air are simulated numerically with allowance for distortions of the light channel due to laser beam refraction in the generated plasma, radiative energy losses, and radiant heat transfer. It is found that instabilities and vortex structures are formed in the hot jet behind the energy release region; flow in this region is nonstationary but periodic. These effects are not observed in the main part of the discharge, which is quite stable. Depending on flow velocity, diffraction in the plasma may lead to both defocusing and focusing of the beam.

  8. Extreme ultraviolet spectra from highly charged gadolinium and neodymium ions in the Large Helical Device and laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Suzuki, C.; Koike, F.; Murakami, I.; Tamura, N.; Sudo, S.; O'Gorman, C.; Li, B.; Harte, C. S.; Donnelly, T.; O'Sullivan, G.

    2013-09-01

    We have observed extreme ultraviolet spectra from highly charged gadolinium (Gd) and neodymium (Nd) ions produced in two different types of light sources for comparative studies. Only broad quasicontinuum feature arising from unresolved transition array was observed in high-density laser produced plasmas of pure/diluted Gd and Nd targets at the University College Dublin, and the spectral feature largely depends on electron temperature in optically thin plasmas produced in the Large Helical Device at the National Institute for Fusion Science. The difference in spectral feature among a number of spectra can be qualitatively interpreted by considering dominant ion stages and opacity effects in the plasmas.

  9. Extinction characterization of soot produced by laser ablating carbon fiber composite materials in air flow

    NASA Astrophysics Data System (ADS)

    Liu, Weiping; Ma, Zhiliang; Zhang, Zhenrong; Zhou, Menglian; Wei, Chenghua

    2015-05-01

    In order to research the dynamic process of energy coupling between an incident laser and a carbon fiber/epoxy resin composite material, an extinction characterization analysis of soot, which is produced by laser ablating and located in an air flow that is tangential to the surface of the composite material, is carried out. By the theory analyses, a relationship of mass extinction coefficient and extinction cross section of the soot is derived. It is obtained that the mass extinction coefficients of soot aggregates are the same as those of the primary particles when they contain only a few primary particles. This conclusion is significant when the soot is located in an air flow field, where the generations of the big soot aggregates are suppressed. A verification experiment is designed. The experiment employs Laser Induced Incandescence technology and laser extinction method for the soot synchronization diagnosis. It can derive a temporal curve of the mass extinction coefficient from the soot concentration and laser transmittance. The experiment results show that the mass extinction coefficient becomes smaller when the air flow velocity is higher. The reason is due to the decrease of the scatter effects of the soot particles. The experiment results agree with the theory analysis conclusion.

  10. Robe Development for Electrical Conductivity Analysis in an Electron Gun Produced Helium Plasma

    NASA Technical Reports Server (NTRS)

    Bragg-Sitton, Shannon M.; Bitteker, Leo; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    The use of magnetohydrodynamic (MHD) power conversion systems, potentially coupled with a fission power source, is currently being investigated as a driver for an advanced propulsion system, such as a plasma thruster. The efficiency of a MHD generator is strongly dependent on the electrical conductivity of the fluid that passes through the generator; power density increases as fluid conductivity increases. Although traditional MHD flows depend on thermal ionization to enhance the electrical conductivity, ionization due to nuclear interactions may achieve a comparable or improved conductivity enhancement while avoiding many of the limitations inherent to thermal ionization. Calculations suggest that nuclear-enhanced electrical conductivity increases as the neutron flux increases; conductivity of pure He-3 greater than 10 mho/m may be achievable if exposed to a flux greater than 10(exp 12) neutrons/cm2/s.) However, this remains to be demonstrated experimentally. An experimental facility has been constructed at the Propulsion Research Center at the NASA Marshall Space Flight Center, using helium as the test fluid. High energy electrons will be used to simulate the effects of neutron-induced ionization of helium gas to produce a plasma. These experiments will be focused on diagnosis of the plasma in a virtually static system; results will be applied to future tests with a MHD system. Initial experiments will utilize a 50 keV electron gun that can operate at up to a current of 200 micro A. Spreading the electron beam over a four inch diameter window results in an electron flux of 1.5x 10(exp 13) e/sq cm/s. The equivalent neutron flux that would produce the same ionization fraction in helium is 1x10(exp 12) n/sq cm/s. Experiments will simulate the neutron generated plasma modeled by Bitteker, which takes into account the products of thermal neutron absorption in He-3, and includes various ion species in estimating the conductivity of the resulting plasma. Several

  11. Parameterization of x-ray production in laser-produced plasmas

    SciTech Connect

    Peek, J.M.

    1980-10-01

    A simple and algebraically tractable model is developed for the efficiency of x-ray production in a certain spectral region by laser driven plasmas. The model is used as a interpolation/extrapolation device for experimental and theoretical results from three different target concepts. These tests indicate that it is of use in its intended capacity. Certain relationships between independent parameters and scaling laws also result from this construction. Most notable among these is the prediction that the efficiency for producing line radiation in a certain narrow energy range scales like the inverse square of this energy.

  12. Spark plasma sintering of alumina nanopowders produced by electrical explosion of wires.

    PubMed

    An, Vladimir; Khasanov, Alexey; de Izarra, Charles

    2015-01-01

    Alumina nanopowders produced by electrical explosion of wires were sintered using the spark plasma sintering technique. The results of XRD analysis show that the main phase in the compacted nanopowders is α-Al2O3. According to the SEM observations, the sintered alumina nanopowder consists of micron-sized faceted grains and nano-sized necked grains. The increase in sintering temperature resulted in a higher density of the sintered powders: from 78.44 to 98.21 % of theoretical density. PMID:26543716

  13. Note: Characterization of the plasma parameters of a capillary discharge-produced plasma channel waveguide to guide an intense laser pulse

    SciTech Connect

    Higashiguchi, Takeshi; Yugami, Noboru; Hikida, Masafumi; Terauchi, Hiromitsu; Bai Jinxiang; Kikuchi, Takashi; Tao Yezheng

    2010-04-15

    We demonstrated the production of an optical waveguide in a capillary discharge-produced plasma using a cylindrical capillary. Plasma parameters of its waveguide were characterized by use of both a Nomarski laser interferometer and a hydrogen plasma line spectrum. A space-averaged maximum temperature of 3.3 eV with electron densities of the order of 10{sup 17} cm{sup -3} was observed at a discharge time of 150 ns and a maximum discharge current of 400 A. An ultrashort, intense laser pulse was guided by use of this plasma channel.

  14. Antimicrobial Efficacy of Two Surface Barrier Discharges with Air Plasma against In Vitro Biofilms

    PubMed Central

    Matthes, Rutger; Bender, Claudia; Schlüter, Rabea; Koban, Ina; Bussiahn, René; Reuter, Stephan; Lademann, Jürgen; Weltmann, Klaus-Dieter; Kramer, Axel

    2013-01-01

    The treatment of infected wounds is one possible therapeutic aspect of plasma medicine. Chronic wounds are often associated with microbial biofilms which limit the efficacy of antiseptics. The present study investigates two different surface barrier discharges with air plasma to compare their efficacy against microbial biofilms with chlorhexidine digluconate solution (CHX) as representative of an important antibiofilm antiseptic. Pseudomonas aeruginosa SG81 and Staphylococcus epidermidis RP62A were cultivated on polycarbonate discs. The biofilms were treated for 30, 60, 150, 300 or 600 s with plasma or for 600 s with 0.1% CHX, respectively. After treatment, biofilms were dispensed by ultrasound and the antimicrobial effects were determined as difference in the number of the colony forming units by microbial culture. A high antimicrobial efficacy on biofilms of both plasma sources in comparison to CHX treatment was shown. The efficacy differs between the used strains and plasma sources. For illustration, the biofilms were examined under a scanning electron microscope before and after treatment. Additionally, cytotoxicity was determined by the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay with L929 mouse fibroblast cell line. The cell toxicity of the used plasma limits its applicability on human tissue to maximally 150 s. The emitted UV irradiance was measured to estimate whether UV could limit the application on human tissue at the given parameters. It was found that the UV emission is negligibly low. In conclusion, the results support the assumption that air plasma could be an option for therapy of chronic wounds. PMID:23894661

  15. Microbiological quality of fresh produce from open air markets and supermarkets in the Philippines.

    PubMed

    Vital, Pierangeli G; Dimasuay, Kris Genelyn B; Widmer, Kenneth W; Rivera, Windell L

    2014-01-01

    This study is the first in the Philippines to conduct a comprehensive assessment of the prevalence of bacterial pathogens and somatic phages in retailed fresh produce used in salad preparation, namely, bell pepper, cabbage, carrot, lettuce, and tomato, using culture and molecular methods. Out of 300 samples from open air and supermarkets, 16.7% tested positive for thermotolerant Escherichia coli, 24.7% for Salmonella spp., and 47% for somatic phages. Results show that counts range from 0.30 to 4.03 log10 CFU/g for E. coli, 0.66 to ≥ 2.34 log10 MPN/g for Salmonella spp., and 1.30 to ≥ 3.00 log 10 PFU/g for somatic phages. Statistical analyses show that there was no significant difference in the microbial counts between open air and supermarkets (α = 0.05). TaqMan and AccuPower Plus DualStar real-time polymerase chain reaction (RT-PCR) was used to confirm the presence of these organisms. The relatively high prevalence of microorganisms observed in produce surveyed signifies reduction in shelf-life and a potential hazard to food safety. This information may benefit farmers, consumers, merchants, and policy makers for foodborne disease detection and prevention. PMID:24963502

  16. 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.

  17. 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.

  18. Aerosynthesis: Growths of Vertically Aligned Carbon Nanofibers with Air DC Plasma

    SciTech Connect

    Kodumagulla, A; Varanasi, V; Pearce, Ryan; Wu, W-C; Hensley, Dale K; Tracy, Joseph B; McKnight, Timothy E; Melechko, Anatoli

    2014-01-01

    Vertically aligned carbon nanofibers (VACNF) have been synthesized in a mixture of acetone and air using catalytic DC plasma enhanced chemical vapor deposition. Typically, ammonia or hydrogen is used as etchant gas in the mixture to remove carbon that otherwise passivates the catalyst surface and impedes growth. Our demonstration of using air as the etchant gas opens up a possibility that ion etching could be sufficient to maintain the catalytic activity state during synthesis. It also demonstrates the path toward growing VACNFs in open atmosphere.

  19. The role of laser wavelength on plasma generation and expansion of ablation plumes in air

    SciTech Connect

    Hussein, A. E.; Diwakar, P. K.; Harilal, S. S.; Hassanein, A.

    2013-04-14

    We investigated the role of excitation laser wavelength on plasma generation and the expansion and confinement of ablation plumes at early times (0-500 ns) in the presence of atmospheric pressure. Fundamental, second, and fourth harmonic radiation from Nd:YAG laser was focused on Al target to produce plasma. Shadowgraphy, fast photography, and optical emission spectroscopy were employed to analyze the plasma plumes, and white light interferometry was used to characterize the laser ablation craters. Our results indicated that excitation wavelength plays a crucial role in laser-target and laser-plasma coupling, which in turn affects plasma plume morphology and radiation emission. Fast photography and shadowgraphy images showed that plasmas generated by 1064 nm are more cylindrical compared to plasmas generated by shorter wavelengths, indicating the role of inverse bremsstrahlung absorption at longer laser wavelength excitation. Electron density estimates using Stark broadening showed higher densities for shorter wavelength laser generated plasmas, demonstrating the significance of absorption caused by photoionization. Crater depth analysis showed that ablated mass is significantly higher for UV wavelengths compared to IR laser radiation. In this experimental study, the use of multiple diagnostic tools provided a comprehensive picture of the differing roles of laser absorption mechanisms during ablation.

  20. Generation of metal ions in the beam plasma produced by a forevacuum-pressure electron beam source

    SciTech Connect

    Tyunkov, A. V.; Yushkov, Yu. G. Zolotukhin, D. B.; Klimov, A. S.; Savkin, K. P.

    2014-12-15

    We report on the production of metal ions of magnesium and zinc in the beam plasma formed by a forevacuum-pressure electron source. Magnesium and zinc vapor were generated by electron beam evaporation from a crucible and subsequently ionized by electron impact from the e-beam itself. Both gaseous and metallic plasmas were separately produced and characterized using a modified RGA-100 quadrupole mass-spectrometer. The fractional composition of metal isotopes in the plasma corresponds to their fractional natural abundance.

  1. Generation of metal ions in the beam plasma produced by a forevacuum-pressure electron beam source

    NASA Astrophysics Data System (ADS)

    Tyunkov, A. V.; Yushkov, Yu. G.; Zolotukhin, D. B.; Savkin, K. P.; Klimov, A. S.

    2014-12-01

    We report on the production of metal ions of magnesium and zinc in the beam plasma formed by a forevacuum-pressure electron source. Magnesium and zinc vapor were generated by electron beam evaporation from a crucible and subsequently ionized by electron impact from the e-beam itself. Both gaseous and metallic plasmas were separately produced and characterized using a modified RGA-100 quadrupole mass-spectrometer. The fractional composition of metal isotopes in the plasma corresponds to their fractional natural abundance.

  2. Ion flux enhancements and oscillations in spatially confined laser produced aluminum plasmas

    SciTech Connect

    Singh, S. C. Fallon, C.; Hayden, P.; Yeates, P.; Costello, J. T.; Mujawar, M.

    2014-09-15

    Ion signals from laser produced plasmas (LPPs) generated inside aluminum rectangular cavities at a fixed depth d = 2 mm and varying width, x = 1.0, 1.6, and 2.75 mm were obtained by spatially varying the position of a negatively biased Langmuir probe. Damped oscillatory features superimposed on Maxwellian distributed ion signals were observed. Depending on the distance of the probe from the target surface, three to twelve fold enhancements in peak ion density were observed via confinement of the LPP, generated within rectangular cavities of varying width which constrained the plasma plume to near one dimensional expansion in the vertical plane. The effects of lateral spatial confinement on the expansion velocity of the LPP plume front, the temperature, density and expansion velocity of ions, enhancement of ion flux, and ion energy distribution were recorded. The periodic behavior of ion signals was analyzed and found to be related to the electron plasma frequency and electron-ion collision frequency. The effects of confinement and enhancement of various ion parameters and expansion velocities of the LPP ion plume are explained on the basis of shock wave theory.

  3. Non-thermal plasma-activated water inactivation of food-borne pathogen on fresh produce.

    PubMed

    Ma, Ruonan; Wang, Guomin; Tian, Ying; Wang, Kaile; Zhang, Jue; Fang, Jing

    2015-12-30

    Non-thermal plasma has been widely considered to be an effective method for decontamination of foods. Recently, numerous studies report that plasma-activated water (PAW) also has outstanding antibacterial ability. This study presents the first report on the potential of PAW for the inactivation of Staphylococcus aureus (S. aureus) inoculated on strawberries. PAW treatments achieved a reduction of S. aureus ranging from 1.6 to 2.3 log at day-0 storage, while 1.7 to 3.4 log at day-4 storage. The inactivation efficiency depended on the plasma-activated time for PAW generation and PAW-treated time of strawberries inoculated with S. aureus. LIVE/DEAD staining and scanning electron microscopy results confirm that PAW could damage the bacterial cell wall. Moreover, optical emission spectra and oxidation reduction potential results demonstrate the inactivation is mainly attributed to oxidative stress induced by reactive oxygen species in PAW. In addition, no significant change was found in color, firmness and pH of the PAW treated strawberries. Thus, PAW can be a promising alternative to traditional sanitizers applied in the fresh produce industry.

  4. Non-thermal plasma-activated water inactivation of food-borne pathogen on fresh produce.

    PubMed

    Ma, Ruonan; Wang, Guomin; Tian, Ying; Wang, Kaile; Zhang, Jue; Fang, Jing

    2015-12-30

    Non-thermal plasma has been widely considered to be an effective method for decontamination of foods. Recently, numerous studies report that plasma-activated water (PAW) also has outstanding antibacterial ability. This study presents the first report on the potential of PAW for the inactivation of Staphylococcus aureus (S. aureus) inoculated on strawberries. PAW treatments achieved a reduction of S. aureus ranging from 1.6 to 2.3 log at day-0 storage, while 1.7 to 3.4 log at day-4 storage. The inactivation efficiency depended on the plasma-activated time for PAW generation and PAW-treated time of strawberries inoculated with S. aureus. LIVE/DEAD staining and scanning electron microscopy results confirm that PAW could damage the bacterial cell wall. Moreover, optical emission spectra and oxidation reduction potential results demonstrate the inactivation is mainly attributed to oxidative stress induced by reactive oxygen species in PAW. In addition, no significant change was found in color, firmness and pH of the PAW treated strawberries. Thus, PAW can be a promising alternative to traditional sanitizers applied in the fresh produce industry. PMID:26282219

  5. Evolution of the free plasma expansion in jets produced by laser ablation

    NASA Astrophysics Data System (ADS)

    Orieux, F.; de Julian, C.; Givord, Dominique

    1998-05-01

    The free expansion evolution of cooper plasma produced by laser ablation is studied by the analysis of the angular distribution and space evolution of the deposition rate and time-of-flight measurements (TOF). The angular distribution of the neutral and ionic species is mainly frontal, but the angular distribution of the neutral species is broader than that of the ionic species. The total number of species, ion dose and most probable ion energy (by solid angle) show no evolution at distances between 7 and 15 cm of the target indicating a global free molecular expansion. The TOF measurements show that the energy distribution of plasma species is different in different directions. Using the Saenger approximation it has been calculated the temperature and velocity of the different ions present in the plume. An increase of the species temperature in the plasma expansion has been observed. The different results obtained by the global measurements and TOF measurements are discussed analyzing the limitation of the Saenger's model and considering the electron-ion coulombic interactions.

  6. Study on hydrogen retention produced from reaction of FLiNaK in ECR plasma

    NASA Astrophysics Data System (ADS)

    Park, Hyunjae; Choi, Yong-Sup; Lho, Taiheop; Plasma Fundamental Technology Development Team

    2011-10-01

    In this study, hydrogen retention from the interaction between an electron cyclone resonance (ECR) plasma and a molten salt, has been experimentally investigated. FLiNaK, which is comprised of LiF (46.5 mol%), NaF (11.5 mol%), and KF (42 mol%), has been used as a molten salt. The molten salt was prepared at the base pressure of 2 × 10-6 torr and 500°C which is above the melting point. However, the chamber pressure was increased up to 3 × 105 mTorr owing to the outgassing from the mixture. The experiments have been perfromed at the working pressure of 1 mTorr at different reaction times. The electron temperature and the ion density in hydrogen ECR plasma were measured by making use of Langmuir probe. Retention of hydrogen in FLiNaK was investigated by means of TDS (Thermal Desorption Spectrometry) method. The chemical species produced from the interaction between the plasma and the molten salt by an optical emission spectroscopy (OES) and a residual gas analyzer (RGA) have been also observed.

  7. Ion flux enhancements and oscillations in spatially confined laser produced aluminum plasmas

    NASA Astrophysics Data System (ADS)

    Singh, S. C.; Fallon, C.; Hayden, P.; Mujawar, M.; Yeates, P.; Costello, J. T.

    2014-09-01

    Ion signals from laser produced plasmas (LPPs) generated inside aluminum rectangular cavities at a fixed depth d = 2 mm and varying width, x = 1.0, 1.6, and 2.75 mm were obtained by spatially varying the position of a negatively biased Langmuir probe. Damped oscillatory features superimposed on Maxwellian distributed ion signals were observed. Depending on the distance of the probe from the target surface, three to twelve fold enhancements in peak ion density were observed via confinement of the LPP, generated within rectangular cavities of varying width which constrained the plasma plume to near one dimensional expansion in the vertical plane. The effects of lateral spatial confinement on the expansion velocity of the LPP plume front, the temperature, density and expansion velocity of ions, enhancement of ion flux, and ion energy distribution were recorded. The periodic behavior of ion signals was analyzed and found to be related to the electron plasma frequency and electron-ion collision frequency. The effects of confinement and enhancement of various ion parameters and expansion velocities of the LPP ion plume are explained on the basis of shock wave theory.

  8. Third harmonic generation in air ambient and laser ablated carbon plasma

    SciTech Connect

    Singh, Ravi Pratap Gupta, Shyam L.; Thareja, Raj K.

    2015-12-15

    We report the third harmonic generation of a nanosecond laser pulse (1.06 μm) in air ambient and in the presence of nanoparticles from laser ablated carbon plasma. Significant decrease in the threshold of third harmonic generation and multi-fold increment in the intensity of generated third harmonic is observed in presence of carbon plasma. The third harmonic in air is due to the quasi-resonant four photon process involving vibrationally excited states of molecular ion of nitrogen due to electron impact ionization and laser pulse. Following optical emission spectroscopic observations we conclude that the presence of C{sub 2} and CN in the ablated plume play a vital role in the observed third harmonic signals.

  9. Time resolved optical diagnostics of ZnO plasma plumes in air

    SciTech Connect

    Gupta, Shyam L.; Singh, Ravi Pratap; Thareja, Raj K.

    2013-10-15

    We report dynamical evolution of laser ablated ZnO plasma plumes using interferometry and shadowgraphy; 2-D fast imaging and optical emission spectroscopy in air ambient at atmospheric pressure. Recorded interferograms using Nomarski interferometer and shadowgram images at various time delays show the presence of electrons and neutrals in the ablated plumes. The inference drawn from sign change of fringe shifts is consistent with two dimensional images of the plume and optical emission spectra at varying time delays with respect to ablating pulse. Zinc oxide plasma plumes are created by focusing 1.06 μm radiation on to ZnO target in air and 532 nm is used as probe beam.

  10. Characterization of a Microhollow Cathode Discharge Plasma in Helium or Air with Water Vapor

    NASA Astrophysics Data System (ADS)

    Fukuhara, D.; Namba, S.; Kozue, K.; Yamasaki, T.; Takiyama, K.

    2013-02-01

    Microhollow cathode discharge (MHCD) plasmas were generated in gas mixtures containing water vapor at pressures of up to 100 kPa of He or 20 kPa of air. The cathode diameter was 1.0 mm with a length of 2.0 mm. The electrical characteristics showed an abnormal glow mode. Spectroscopic measurements were carried out to examine the plasma and radicals. An analysis of the spectral profile of Hα at 656.3 nm enabled a derivation of the electron densities, namely 2×1014 cm-3 (at 10 kPa) and 6×1014 cm-3 (at 4 kPa) for the helium and air atmospheres, respectively, in the negative glow region. By comparing the observed OH radical spectra with those calculated by the simulation code LIFBASE, the gas temperature was deduced to be 900 K for 4 kPa of He at a discharge current of 50 mA.

  11. Plasma column and nano-powder generation from solid titanium by localized microwaves in air

    NASA Astrophysics Data System (ADS)

    Popescu, Simona; Jerby, Eli; Meir, Yehuda; Barkay, Zahava; Ashkenazi, Dana; Mitchell, J. Brian A.; Le Garrec, Jean-Luc; Narayanan, Theyencheri

    2015-07-01

    This paper studies the effect of a plasma column ejected from solid titanium by localized microwaves in an ambient air atmosphere. Nanoparticles of titanium dioxide (titania) are found to be directly synthesized in this plasma column maintained by the microwave energy in the cavity. The process is initiated by a hotspot induced by localized microwaves, which melts the titanium substrate locally. The molten hotspot emits ionized titanium vapors continuously into the stable plasma column, which may last for more than a minute duration. The characterization of the dusty plasma obtained is performed in-situ by small-angle X-ray scattering (SAXS), optical spectroscopy, and microwave reflection analyses. The deposited titania nanoparticles are structurally and morphologically analyzed by ex-situ optical and scanning-electron microscope observations, and also by X-ray diffraction. Using the Boltzmann plot method combined with the SAXS results, the electron temperature and density in the dusty plasma are estimated as ˜0.4 eV and ˜1019 m-3, respectively. The analysis of the plasma product reveals nanoparticles of titania in crystalline phases of anatase, brookite, and rutile. These are spatially arranged in various spherical, cubic, lamellar, and network forms. Several applications are considered for this process of titania nano-powder production.

  12. Formation of plasma channels in air under filamentation of focused ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Ionin, A. A.; Seleznev, L. V.; Sunchugasheva, E. S.

    2015-03-01

    The formation of plasma channels in air under filamentation of focused ultrashort laser pulses was experimentally and theoretically studied together with theoreticians of the Moscow State University and the Institute of Atmospheric Optics. The influence of various characteristics of ultrashort laser pulses on these plasma channels is discussed. Plasma channels formed under filamentation of focused laser beams with a wavefront distorted by spherical aberration (introduced by adaptive optics) and by astigmatism, with cross-section spatially formed by various diaphragms and with different UV and IR wavelengths, were experimentally and numerically studied. The influence of plasma channels created by a filament of a focused UV or IR femtosecond laser pulse (λ = 248 nm or 740 nm) on characteristics of other plasma channels formed by a femtosecond pulse at the same wavelength following the first one with varied nanosecond time delay was also experimentally studied. An application of plasma channels formed due to the filamentation of focused UV ultrashort laser pulses including a train of such pulses and a combination of ultrashort and long (~100 ns) laser pulses for triggering and guiding long (~1 m) electric discharges is discussed.

  13. 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.

  14. Plasma column and nano-powder generation from solid titanium by localized microwaves in air

    SciTech Connect

    Popescu, Simona; Jerby, Eli Meir, Yehuda; Ashkenazi, Dana; Barkay, Zahava; Mitchell, J. Brian A.; Le Garrec, Jean-Luc; Narayanan, Theyencheri

    2015-07-14

    This paper studies the effect of a plasma column ejected from solid titanium by localized microwaves in an ambient air atmosphere. Nanoparticles of titanium dioxide (titania) are found to be directly synthesized in this plasma column maintained by the microwave energy in the cavity. The process is initiated by a hotspot induced by localized microwaves, which melts the titanium substrate locally. The molten hotspot emits ionized titanium vapors continuously into the stable plasma column, which may last for more than a minute duration. The characterization of the dusty plasma obtained is performed in-situ by small-angle X-ray scattering (SAXS), optical spectroscopy, and microwave reflection analyses. The deposited titania nanoparticles are structurally and morphologically analyzed by ex-situ optical and scanning-electron microscope observations, and also by X-ray diffraction. Using the Boltzmann plot method combined with the SAXS results, the electron temperature and density in the dusty plasma are estimated as ∼0.4 eV and ∼10{sup 19 }m{sup −3}, respectively. The analysis of the plasma product reveals nanoparticles of titania in crystalline phases of anatase, brookite, and rutile. These are spatially arranged in various spherical, cubic, lamellar, and network forms. Several applications are considered for this process of titania nano-powder production.

  15. X-ray imaging of laser produced plasmas by a compound 3D x-ray lens

    NASA Astrophysics Data System (ADS)

    Garanin, R. V.; Pavlov, G. A.; Suslov, N. A.; Treushnikov, V. M.; Treushnikov, V. V.; Zhidkov, N. V.

    2015-04-01

    Pilot scheme for the study of plasma under extreme condition is implemented using a compound 3D X-ray lens. Hard X-ray image of laser plasma produced by irradiating of copper foil by intense laser pulse was recorded using this lens.

  16. Colliding laser-produced plasmas as targets for laser-generated extreme ultraviolet sources

    SciTech Connect

    Cummins, T.; O'Gorman, C.; Dunne, P.; Sokell, E.; O'Sullivan, G.; Hayden, P.

    2014-07-28

    Colliding plasmas produced by neodymium-doped yttrium aluminium garnet (Nd:YAG) laser illumination of tin wedge targets form stagnation layers, the physical parameters of which can be controlled to optimise coupling with a carbon dioxide (CO{sub 2}) heating laser pulse and subsequent extreme ultraviolet (EUV) production. The conversion efficiency (CE) of total laser energy into EUV emission at 13.5 nm ± 1% was 3.6%. Neglecting both the energy required to form the stagnation layer and the EUV light produced before the CO{sub 2} laser pulse is incident results in a CE of 5.1% of the CO{sub 2} laser energy into EUV light.

  17. Elevated Plasma Endothelin-1 and Pulmonary Arterial Pressure in Children Exposed to Air Pollution

    PubMed Central

    Calderón-Garcidueñas, Lilian; Vincent, Renaud; Mora-Tiscareño, Antonieta; Franco-Lira, Maricela; Henríquez-Roldán, Carlos; Barragán-Mejía, Gerardo; Garrido-García, Luis; Camacho-Reyes, Laura; Valencia-Salazar, Gildardo; Paredes, Rogelio; Romero, Lina; Osnaya, Hector; Villarreal-Calderón, Rafael; Torres-Jardón, Ricardo; Hazucha, Milan J.; Reed, William

    2007-01-01

    Background Controlled exposures of animals and humans to particulate matter (PM) or ozone air pollution cause an increase in plasma levels of endothelin-1, a potent vasoconstrictor that regulates pulmonary arterial pressure. Objectives The primary objective of this field study was to determine whether Mexico City children, who are chronically exposed to levels of PM and O3 that exceed the United States air quality standards, have elevated plasma endothelin-1 levels and pulmonary arterial pressures. Methods We conducted a study of 81 children, 7.9 ± 1.3 years of age, lifelong residents of either northeast (n = 19) or southwest (n = 40) Mexico City or Polotitlán (n = 22), a control city with PM and O3 levels below the U.S. air quality standards. Clinical histories, physical examinations, and complete blood counts were done. Plasma endothelin-1 concentrations were determined by immunoassay, and pulmonary arterial pressures were measured by Doppler echocardiography. Results Mexico City children had higher plasma endothelin-1 concentrations compared with controls (p < 0.001). Mean pulmonary arterial pressure was elevated in children from both northeast (p < 0.001) and southwest (p < 0.05) Mexico City compared with controls. Endothelin-1 levels in Mexico City children were positively correlated with daily outdoor hours (p = 0.012), and 7-day cumulative levels of PM air pollution < 2.5 μm in aerodynamic diameter (PM2.5) before endothelin-1 measurement (p = 0.03). Conclusions Chronic exposure of children to PM2.5 is associated with increased levels of circulating endothelin-1 and elevated mean pulmonary arterial pressure. PMID:17687455

  18. In-situ formation of multiphase air plasma sprayed barrier coatings for turbine components

    DOEpatents

    Subramanian, Ramesh

    2001-01-01

    A turbine component (10), such as a turbine blade, is provided which is made of a metal alloy (22) and a base, planar-grained thermal barrier layer (28) applied by air plasma spraying on the alloy surface, where a heat resistant ceramic oxide overlay material (32') covers the bottom thermal barrier coating (28), and the overlay material is the reaction product of the precursor ceramic oxide overlay material (32) and the base thermal barrier coating material (28).

  19. Size-dependent mechanical properties of PVA nanofibers reduced via air plasma treatment

    NASA Astrophysics Data System (ADS)

    Fu, Qiang; Jin, Yu; Song, Xuefeng; Gao, Jingyun; Han, Xiaobing; Jiang, Xingyu; Zhao, Qing; Yu, Dapeng

    2010-03-01

    Organic nanowires/fibers have great potential in applications such as organic electronics and soft electronic techniques. Therefore investigation of their mechanical performance is of importance. The Young's modulus of poly(vinyl alcohol) (PVA) nanofibers was analyzed by scanning probe microscopy (SPM) methods. Air plasma treatment was used to reduce the nanofibers to different sizes. Size-dependent mechanical properties of PVA nanofibers were studied and revealed that the Young's modulus increased dramatically when the scales became very small (<80 nm).

  20. A model for residual stress evolution in air-plasma-sprayed zirconia thermal barrier coatings

    SciTech Connect

    Nair, B. G.; Singh, J. P.; Grimsditch, M.

    2000-02-28

    Ruby fluorescence spectroscopy indicates that residual stress in air-plasma-sprayed zirconia thermal barrier coatings is a function of the local interface geometry. The stress profile of a simulated rough interface characterized by ``peaks'' and ``valleys'' was modeled with a finite-element approach that accounted for thermal mismatch, oxide scale growth, and top coat sintering. Dependence of the stress profile on interface geometry and microstructure was investigated, and the results were compared with measured stresses.

  1. Sterilization effect of atmospheric pressure non-thermal air plasma on dental instruments

    PubMed Central

    Sung, Su-Jin; Huh, Jung-Bo; Yun, Mi-Jung; Chang, Brian Myung W.; Jeong, Chang-Mo

    2013-01-01

    PURPOSE Autoclaves and UV sterilizers have been commonly used to prevent cross-infections between dental patients and dental instruments or materials contaminated by saliva and blood. To develop a dental sterilizer which can sterilize most materials, such as metals, rubbers, and plastics, the sterilization effect of an atmospheric pressure non-thermal air plasma device was evaluated. MATERIALS AND METHODS After inoculating E. coli and B. subtilis the diamond burs and polyvinyl siloxane materials were sterilized by exposing them to the plasma for different lengths of time (30, 60, 90, 120, 180 and, 240 seconds). The diamond burs and polyvinyl siloxane materials were immersed in PBS solutions, cultured on agar plates and quantified by counting the colony forming units. The data were analyzed using one-way ANOVA and significance was assessed by the LSD post hoc test (α=0.05). RESULTS The device was effective in killing E. coli contained in the plasma device compared with the UV sterilizer. The atmospheric pressure non-thermal air plasma device contributed greatly to the sterilization of diamond burs and polyvinyl siloxane materials inoculated with E. coli and B. subtilis. Diamond burs and polyvinyl siloxane materials inoculated with E. coli was effective after 60 and 90 seconds. The diamond burs and polyvinyl siloxane materials inoculated with B. subtilis was effective after 120 and 180 seconds. CONCLUSION The atmospheric pressure non-thermal air plasma device was effective in killing both E. coli and B. subtilis, and was more effective in killing E. coli than the UV sterilizer. PMID:23508991

  2. Identification of hydrogenlike and heliumlike transitions in the spectrum of laser-produced magnesium plasmas

    NASA Technical Reports Server (NTRS)

    Moreno, J. C.; Goldsmith, S.; Griem, H. R.; Cohen, Leonard; Knauer, J.

    1990-01-01

    Nonresonance spectral lines of Mg XII and Mg XI emitted by magnesium laser-produced plasmas have been observed in the extreme-vacuum-ultraviolet region and their transitions classified. As many as eight beams of the Omega laser system of the Laboratory for Laser Energetics at the University of Rochester were linearly focused onto magnesium-coated flat targets to produce linear plasma radiation sources from 3 to 6 mm long. The spectra were photographed end-on with a grazing-incidence spectrograph. The identified Mg XII lines are classified as 2s-3p, 2p-3d, 2s-4p, 2p-4d, and 3d-4f transitions. The identified Mg XI lines are classified as 1s2s-1s3p, 1s2p-1s3d, 1s2p-1s4d, 1s3p-1s4d, and 1s3d-1s4f.

  3. Plasma characteristics of argon glow discharge produced by AC power supply operating at low frequencies

    SciTech Connect

    Kongpiboolkid, Watcharapon; Mongkolnavin, Rattachat

    2015-04-24

    Non-thermal properties of Argon glow discharge operating with various operating pressures were measured and presented in this work. The Argon plasma is produced by a parallel conducting electrodes coupling with a high voltage AC power supply. The power supply can generate high AC voltage at various frequencies. The frequencies for the operation are in the range of a few kHz. The system is capable of generating electric field between the two metal electrodes discharge system. The characteristics of plasma produced were measured by optical emission spectroscopy (OES) technique where electron temperature (T{sub e}) and electron number density (n{sub e}) can be determined by line intensity ratio method. The value of electron number density was then determined from the Saha-Eggert equation. Our results show that the electron number density of the discharge obtained is of the order of 10{sup −17} − 10{sup −18} m{sup −3} where the electron temperature is between 1.00−2.00 eV for various operating frequencies used which are in good agreement with similar results published earlier.

  4. Emerging trends in X-ray spectroscopic studies of plasma produced by intense laser beams

    SciTech Connect

    Arora, V.; Chakera, J. A.; Naik, P. A.; Gupta, P. D.

    2015-07-31

    X-ray line emission from hot dense plasmas, produced by ultra-short high intensity laser systems, has been studied experimentally in recent years for applications in materials science as well as for back-lighter applications. By virtue of the CPA technology, several laser facilities delivering pulses with peak powers in excess of one petawatt (focused intensities > 10{sup 20} W-cm{sup −2}) have either been commissioned across the globe during the last few years or are presently under construction. On the other hand, hard x-ray sources on table top, generating ultra-short duration x-rays at a repetition rate up to 10 kHz, are routinely available for time resolved x-ray diffraction studies. In this paper, the recent experiments on x-ray spectroscopic studies of plasma produced by 45 fs, Ti:sapphire laser pulses (focused iintensity > 10{sup 18} W-cm{sup −2}) at RRCAT Indore will be presented.

  5. Specific aquaporins facilitate Nox-produced hydrogen peroxide transport through plasma membrane in leukaemia cells.

    PubMed

    Vieceli Dalla Sega, Francesco; Zambonin, Laura; Fiorentini, Diana; Rizzo, Benedetta; Caliceti, Cristiana; Landi, Laura; Hrelia, Silvana; Prata, Cecilia

    2014-04-01

    In the last decade, the generation and the role of reactive oxygen species (ROS), particularly hydrogen peroxide, in cell signalling transduction pathways have been intensively studied, and it is now clear that an increase of ROS level affects cellular growth and proliferation pathways related to cancer development. Hydrogen peroxide (H2O2) has been long thought to permeate biological membranes by simple diffusion since recent evidence challenged this notion disclosing the role of aquaporin water channels (AQP) in mediating H2O2 transport across plasma membranes. We previously demonstrated that NAD(P)H oxidase (Nox)-generated ROS sustain glucose uptake and cellular proliferation in leukaemia cells. The aim of this study was to assess whether specific AQP isoforms can channel Nox-produced H2O2 across the plasma membrane of leukaemia cells affecting downstream pathways linked to cell proliferation. In this work, we demonstrate that AQP inhibition caused a decrease in intracellular ROS accumulation in leukaemia cells both when H2O2 was produced by Nox enzymes and when it was exogenously added. Furthermore, AQP8 overexpression or silencing resulted to modulate VEGF capacity of triggering an H2O2 intracellular level increase or decrease, respectively. Finally, we report that AQP8 is capable of increasing H2O2-induced phosphorylation of both PI3K and p38 MAPK and that AQP8 expression affected positively cell proliferation. Taken together, the results here reported indicate that AQP8 is able to modulate H2O2 transport through the plasma membrane affecting redox signalling linked to leukaemia cell proliferation.

  6. Development of liquid-jet laser-produced plasma light source for EUV lithography

    NASA Astrophysics Data System (ADS)

    Abe, Tamotsu; Suganuma, Takashi; Imai, Yousuke; Sugimoto, Yukihiko; Someya, Hiroshi; Hoshino, Hideo; Soumagne, Georg; Komori, Hiroshi; Mizoguchi, Hakaru; Endo, Akira; Toyoda, Koichi

    2003-06-01

    The Extreme UV Lithography System Development Association (EUVA) was established in Japan in May 2002 and is supported by the Ministry of Economy, Trade and Industry (METI). EUVA started the light soruce development in September 2002. This development is done by the assocaition members Gigaphoton, Ushio, Komatsu, Canon, Nikon, the National Institute of Advanced Industrial Sciecne and Technology (AIST) and several Japanese universities. The target of the four-year project is the development of a EUV light source with 10W clean focus point power. For the end of the fiscal year 2003 the development of a 4W EUV light source (clean focus point power) is planned. Both, Laser-Produced-Plasma (LPP) and Discharge-Produced-Plasma (DPP) EUV light sources are investigated at first. Our group at the EUVA Hiratsuka R&D Center is working on LPP sources. We are currently focusing on the development of a driver laser and a liquid Xenon plasma target. The laser is a Nd:YAG MOPA (Master Oscillator and Power Amplifier) system oscillating at 1064 nm. Average power, repetition rate and pulse duration of the laser system are 500 Watt, 10 kHa and 30nsec, respectively. The Xenon liquefication system operates at a maximum pressure of 5MPa and a temperature range between 160 K and 190 K. The pressure inside the vacuum chamber is below 0.1Pa during system operation. This paper presents the current status of the EUV system component development as well as first experimental results of generated EUV radiation.

  7. Time of flight emission spectroscopy of laser produced nickel plasma: Short-pulse and ultrafast excitations

    SciTech Connect

    Smijesh, N.; Chandrasekharan, K.; Joshi, Jagdish C.; Philip, Reji

    2014-07-07

    We report the experimental investigation and comparison of the temporal features of short-pulse (7 ns) and ultrafast (100 fs) laser produced plasmas generated from a solid nickel target, expanding into a nitrogen background. When the ambient pressure is varied in a large range of 10⁻⁶Torr to 10²Torr, the plume intensity is found to increase rapidly as the pressure crosses 1 Torr. Time of flight (TOF) spectroscopy of emission from neutral nickel (Ni I) at 361.9 nm (3d⁹(²D) 4p → 3d⁹(²D) 4s transition) reveals two peaks (fast and slow species) in short-pulse excitation and a single peak in ultrafast excitation. The fast and slow peaks represent recombined neutrals and un-ionized neutrals, respectively. TOF emission from singly ionized nickel (Ni II) studied using the 428.5 nm (3p⁶3d⁸(³P) 4s→ 3p⁶3d⁹ 4s) transition shows only a single peak for either excitation. Velocities of the neutral and ionic species are determined from TOF measurements carried out at different positions (i.e., at distances of 2 mm and 4 mm, respectively, from the target surface) on the plume axis. Measured velocities indicate acceleration of neutrals and ions, which is caused by the Coulomb pull of the electrons enveloping the plume front in the case of ultrafast excitation. Both Coulomb pull and laser-plasma interaction contribute to the acceleration in the case of short-pulse excitation. These investigations provide new information on the pressure dependent temporal behavior of nickel plasmas produced by short-pulse and ultrafast laser pulses, which have potential uses in applications such as pulsed laser deposition and laser-induced nanoparticle generation.

  8. Diamond-like carbon produced by plasma source ion implantation as a corrosion barrier

    SciTech Connect

    Lillard, R.S.; Butt, D.P.; Taylor, T.N.; Walter, K.C.; Nastasi, M.

    1998-03-01

    There currently exists a broad range of applications for which the ability to produce an adherent, hard, wear and, corrosion-resistant coating plays a vital role. These applications include engine components, orthopedic devices, textile manufacturing components, hard disk media, optical coatings, and cutting and machining tools (e.g., punches, taps, scoring dies, and extrusion dies). Ion beam processing can play an important role in all of these technologies. Plasma source ion implantation (PSII) is an emerging technology which has the potential to overcome the limitations of conventional ion implantation by: (1) reducing the time and expense for implanting onto complex shapes and large areas and (2) extending the thickness of the modification zone through ion beam enhanced plasma growth of surface coatings. In PSII, targets are placed directly in a plasma source and then pulse biased to produce a non-line-of-sight process for complex-shaped targets without complex fixturing. If the pulse bias is a relatively high negative potential (20 to 100 kV) ion implantation will result. If however, a low voltage (50--1,200 eV) high duty cycle pulse bias is applied, film deposition from the chamber gas will result, thereby increasing the extent of the surface modification into the 1--10 micron regime. To evaluate the potential for DLC to be used as a corrosion barrier, Electrochemical Impedance Spectroscopy (EIS) and traditional electrochemistry techniques were used to investigate the breakdown mechanism in chloride and nonchloride containing environments. The effect of surface preparation on coating breakdown was also evaluated.

  9. Observation of plasma array dynamics in 110 GHz millimeter-wave air breakdown

    SciTech Connect

    Cook, Alan M.; Hummelt, Jason S.; Shapiro, Michael A.; Temkin, Richard J.

    2011-10-15

    We present dynamical measurements of self-organizing arrays of plasma structures in air induced by a 110 GHz millimeter-wave beam with linear or circular polarization. The formation of the individual plasmas and the growth of the array pattern are studied using a fast-gated (5-10 ns) intensified camera. We measure the time-dependent speed at which the array pattern propagates in discrete steps toward the millimeter-wave source, observing a peak speed greater than 100 km/s. We observe the expansion of an initially spherical plasma into a disk or an elongated filament, depending on the polarization of the incident beam. The results show good agreement with one-dimensional ionization-diffusion theory and two-dimensional simulations.

  10. Experimental investigation on plasma-assisted combustion characteristics of premixed propane/air mixture

    NASA Astrophysics Data System (ADS)

    Liu, Xingjian; He, Liming; Yu, Jinlu; Zeng, Hao; Jin, Tao

    2015-06-01

    A detailed study on the plasma-assisted combustion (PAC) characteristics of premixed propane/air mixture is presented. The PAC is measured electrically, as well as optically with a multichannel spectrometer. The characteristics are demonstrated by stable combustion temperature and combustion stability limits, and the results are compared with conventional combustion (CC). Stable combustion temperature measurements show that the introduction of PAC into combustion system can increase the stable combustion temperature, and the increment is more notable with an increase of discharge voltage. Besides, the rich and weak limits of combustion stability are both enlarged when plasma is applied into the combustion process and the increase of discharge voltage results in the expansion of combustion stability limits as well. The measurements of temperature head and emission spectrum illustrate that the kinetic enhancement caused by reactive species in plasma is the main enhancement pathway for current combustion system.

  11. REMC computer simulations of the thermodynamic properties of argon and air plasmas

    NASA Astrophysics Data System (ADS)

    Lisal, Martin; Smith, William R.; Bures, Michal; Vacek, Vaclav; Navratil, Jiri

    The reaction ensemble Monte Carlo (REMC) computer simulation method (Smith, W. R., and Triska, B., 1994, J. chem. Phys. , 100, 3019) is employed to calculate reaction equilibrium in multi-reaction systems using a molecular based system model. The compositions and thermodynamic properties of argon plasmas (7 reactions) and air plasmas (26 reactions) are studied using a molecular level model based on the underlying atomic and ionic interactions. In the context of the specified molecular model, the REMC approach gives an essentially exact description of the system thermodynamics. Calculations are made of plasma compositions, molar enthalpies, molar volumes, molar heat capacities, and coefficients of cubic expansion over a range of temperatures up to 100000K at a pressure of 10bar, and the results are compared with those obtained using the macroscopic level ideal-gas and Debye-Hückel approximations.

  12. Frontal vitrification of PDMS using air plasma and consequences for surface wrinkling.

    PubMed

    Nania, Manuela; Matar, Omar K; Cabral, João T

    2015-04-21

    We study the surface oxidation of polydimethylsiloxane (PDMS) by air plasma exposure and its implications for the mechanically-induced surface wrinkling of the resulting glass-elastomer bilayers. The effect of plasma frequency (kHz and MHz), oxygen content (from O2 to air), pressure (0.5 ≤ P ≤ 1.5 mbar), as well as exposure time and power, is quantified in terms of the resulting glassy skin thickness h, inferred from wrinkling experiments. The glassy skin thickness is found to increase logarithmically with an exposure time t, for different induction powers p, and all data collapse in terms of a plasma dose, D ≡ p × t. The kinetics of film propagation are found to increase with the oxygen molar fraction yO2 and decrease with the gas pressure P, allowing both the wrinkling wavelength λ and amplitude A to be effectively controlled by gas pressure and composition. A generalised relationship for frontal vitrification is obtained by re-scaling all λ and h data by D/P. A coarse-grained wave propagation model effectively describes and quantifies the process stages (induction, skin formation and propagation) under all the conditions studied. Equipped with this knowledge, we further expand the capabilities of plasma oxidation for PDMS wrinkling, and a wavelength of λ ≈ 100 nm is readily attained with a modest strain εprestrain ≈ 20%.

  13. Laser-induced micro-plasmas in air for incoherent broadband cavity-enhanced absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Ruth, Albert; Dixneuf, Sophie; Orphal, Johannes

    2016-04-01

    Incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) is an experimentally straightforward absorption method where the intensity of light transmitted by an optically stable (high finesse) cavity is measured. The technique is realized using broadband incoherent sources of radiation and therefore the amount of light transmitted by a cavity consisting of high reflectance mirrors (typically R > 99.9%) can be low. In order to find an alternative to having an incoherent light source outside the cavity, an experiment was devised, where a laser-induced plasma in ambient air was generated inside a quasi-confocal cavity by a high-power femtosecond laser. The emission from the laser-induced plasma was utilized as pulsed broadband light source. The time-dependent spectra of the light leaking from the cavity were compared with those of the laser-induced plasma emission without the cavity. It was found that the light emission was sustained by the cavity despite the initially large optical losses caused by the laser-induced plasma in the cavity. The light sustained by the cavity was used to measure part of the S1 ← S0 absorption spectrum of gaseous azulene at its vapour pressure at room temperature in ambient air, as well as the strongly forbidden γ-band in molecular oxygen (b1Σ(2,0) ← X3Σ(0,0)).

  14. Spectroscopic and electrical characters of SBD plasma excited by bipolar nanosecond pulse in atmospheric air.

    PubMed

    Zhao, Zi-Lu; Yang, De-Zheng; Wang, Wen-Chun; Yuan, Hao; Zhang, Li; Wang, Sen; Liu, Zhi-Jie; Zhang, Shuai

    2016-05-15

    In this paper, an atmospheric surface barrier discharge (SBD) generated by annular electrodes in quartz tube is presented through employing bipolar nanosecond pulse voltage in air. The discharge images, waveforms of pulse voltage and discharge current, and optical emission spectra emitted from the discharges are recorded and calculated. A spectra simulation method is developed to separate the overlap of the secondary diffraction spectra which are produced by grating in monochromator, and N2 (B(3)Πg→A(3)Σu(+)) and O (3p(5)P→3s(5)S2(o)) are extracted. The effects of pulse voltage and discharge power on the emission intensities of OH (A(2)Σ(+)→X(2)Пi), N2(+) (B(2)Σu(+)→X(2)Σg(+)), N2 (C(3)Πu→B(3)Πg), N2 (B(3)Πg→A(3)Σu(+)), and O (3p(5)P→3s(5)S2(o)) are investigated. It is found that increasing the pulse peak voltage can lead to an easier formation of N2(+) (B(2)Σu(+)) than that of N2 (C(3)Πu). Additionally, vibrational and rotational temperatures of the plasma are determined by comparing the experimental and simulated spectra of N2(+) (B(2)Σu(+)→X(2)Σg(+)), and the results show that the vibrational and rotational temperatures are 3250±20K and 350±5K under the pulse peak voltage of 28kV, respectively. PMID:26924210

  15. Spectroscopic and electrical characters of SBD plasma excited by bipolar nanosecond pulse in atmospheric air

    NASA Astrophysics Data System (ADS)

    Zhao, Zi-Lu; Yang, De-Zheng; Wang, Wen-Chun; Yuan, Hao; Zhang, Li; Wang, Sen; Liu, Zhi-Jie; Zhang, Shuai

    2016-05-01

    In this paper, an atmospheric surface barrier discharge (SBD) generated by annular electrodes in quartz tube is presented through employing bipolar nanosecond pulse voltage in air. The discharge images, waveforms of pulse voltage and discharge current, and optical emission spectra emitted from the discharges are recorded and calculated. A spectra simulation method is developed to separate the overlap of the secondary diffraction spectra which are produced by grating in monochromator, and N2 (B3Πg → A3Σu+) and O (3p5P → 3s5S2o) are extracted. The effects of pulse voltage and discharge power on the emission intensities of OH (A2Σ+ → X2Пi), N2+ (B2Σu+ → X2Σg+), N2 (C3Πu → B3Πg), N2 (B3Πg → A3Σu+), and O (3p5P → 3s5S2o) are investigated. It is found that increasing the pulse peak voltage can lead to an easier formation of N2+ (B2Σu+) than that of N2 (C3Πu). Additionally, vibrational and rotational temperatures of the plasma are determined by comparing the experimental and simulated spectra of N2+ (B2Σu+ → X2Σg+), and the results show that the vibrational and rotational temperatures are 3250 ± 20 K and 350 ± 5 K under the pulse peak voltage of 28 kV, respectively.

  16. A Langmuir Probe Diagnostic for Use in Inhomogeneous, Time-Varying Plasmas Produced by High-Energy Laser Ablation

    SciTech Connect

    Patterson, J R; Emig, J A; Fournier, K B; Jenkins, P P; Trautz, K M; Seiler, S W; Davis, J F

    2012-05-01

    Langmuir probes (LP) are used extensively to characterize plasma environments produced by radio frequency, pulsed plasma thrusters, and laser ablation. We discuss here the development of a LP diagnostic to examine high-density, high-temperature inhomogeneous plasmas such as those that can be created at the University of Rochester's Laboratory for Laser Energetics OMEGA facility. We have configured our diagnostic to examine the velocity of the plasma expanding from the target. We observe velocities of approximately 16-17 cm/{micro}s, with individual LP currents displaying complex structures, perhaps due to the multiple atomic species and ionization states that exist.

  17. Laser-induced plasmas in air studied using two-color interferometry

    NASA Astrophysics Data System (ADS)

    Yang, Zefeng; Wu, Jian; Wei, Wenfu; Li, Xingwen; Han, Jiaxun; Jia, Shenli; Qiu, Aici

    2016-08-01

    Temporally and spatially resolved density profiles of Cu atoms, electrons, and compressed air, from laser-induced copper plasmas in air, are measured using fast spectral imaging and two-color interferometry. From the intensified CCD images filtered by a narrow-band-pass filter centered at 515.32 nm, the Cu atoms expansion route is estimated and used to determine the position of the fracture surface between the Cu atoms and the air. Results indicate that the Cu atoms density at distances closer to the target (0-0.4 mm) is quite low, with the maximum density appearing at the edge of the plasma's core being ˜4.6 × 1024 m-3 at 304 ns. The free electrons are mainly located in the internal region of the plume, which is supposed to have a higher temperature. The density of the shock wave is (4-6) × 1025 m-3, corresponding to air compression of a factor of 1.7-2.5.

  18. Open Air Silicon Deposition by Atmospheric Pressure Plasma under Local Ambient Gas Control

    NASA Astrophysics Data System (ADS)

    Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

    2015-09-01

    In this paper, we report open air silicon (Si) deposition by combining a silane free Si deposition technology and a newly developed local ambient gas control technology. Recently, material processing in open air has been investigated intensively. While a variety of materials have been deposited, there were only few reports on Si deposition due to the susceptibility to contamination and the hazardous nature of source materials. Since Si deposition is one of the most important processes in device fabrication, we have developed open air silicon deposition technologies in BEANS project. For a clean and safe process, a local ambient gas control head was designed. Process gas leakage was prevented by local evacuation, and air contamination was shut out by inert curtain gas. By numerical and experimental investigations, a safe and clean process condition with air contamination less than 10 ppm was achieved. Si film was deposited in open air by atmospheric pressure plasma enhanced chemical transport under the local ambient gas control. The film was microcrystalline Si with the crystallite size of 17 nm, and the Hall mobility was 2.3 cm2/V .s. These properties were comparable to those of Si films deposited in a vacuum chamber. This research has been conducted as one of the research items of New Energy and Industrial Technology Development Organization ``BEANS'' project.

  19. A method to measure the electron temperature and density of a laser-produced plasma by Raman scattering

    SciTech Connect

    Jang, H.; Hur, M. S.; Lee, J. M.; Suk, H.; Cho, M. H.; Namkung, W.

    2008-08-18

    A method is proposed to investigate the electron temperature and density of a laser-produced plasma simultaneously, using the temperature dependence difference of the Raman forward scattering (RFS) and backward scattering (RBS). Density and temperature dependence of spectra from the RBS and the RFS in a laser produced plasma were investigated by one-dimensional particle-in-cell simulations in the nonrelativistic regime. This technique has a great advantage as a simple diagnostic of plasma characteristics in the sense that it can be performed only with the pump laser, without any additional probe laser.

  20. Optimization of laser-produced plasmas for nanolithography and materials detection

    NASA Astrophysics Data System (ADS)

    Freeman, Justin R.

    In this work, laser-matter interactions and resultant plasma emission using traditional short pulsed lasers are studied in the context of semiconductor lithography and material sensing applications. Ultrafast laser ablation and plasma emission results are then compared to those using traditional short pulsed lasers. Then fundamental laser-matter interactions and ablation processes of ultrafast lasers are investigated. This work focuses on laser-produced plasma (LPP) light sources at extreme ultraviolet (EUV) wavelengths. The out-of-band (OoB) light emission as well as ionic and atomic debris from the plasma source, which are capable of damaging collection optics, have been studied as a function of incident laser wavelength to characterize the angular distributions of debris and identify the differences in debris from longer and shorter laser excitation wavelengths. By applying a prepulse to create improved laser-target coupling conditions, conversion efficiency (CE) from laser energy to 13.5 nm light emission from the plasma source can be improved by 30% or higher. Energetic ions escaping from the plasma can cause significant damage to light collection optics, greatly reducing their lifetimes, but by implementing a prepulse, it has been shown that most-probable ion energies can be reduced significantly, minimizing damage caused to collection optics. Laser-induced breakdown spectroscopy (LIBS) is a technique used to identify the elemental constituents of unknown samples by studying the optical light spectra emitted from a LPP. Despite advantages such as in situ capabilities and near-instant results, detection limits of LIBS systems are not as competitive as other laboratory-based systems. To overcome such limitations, a double pulse (DP) LIBS system is arranged using a long-wavelength laser for the second pulse and heating of the plume created by the first pulse. Detector gating parameters were optimized and different first-pulse laser energies were investigated to

  1. Sonic booms produced by US Air Force and US Navy aircraft: Measured data

    NASA Astrophysics Data System (ADS)

    Lee, R. A.; Downing, J. M.

    1991-01-01

    A sonic measurement program was conducted at Edwards Air Force Base. Sonic boom signatures, produced by F-4, F-14, F-15, F-16, F-18, F-111, SR-71, and T-38 aircraft, were obtained under the flight track and at various lateral sites which were located up to 18 miles off-track. Thirteen monitors developed by Det 1 AL/BBE were used to collect full sonic boom waveforms, and nine modified dosimeters were used to collect supplemental peak overpressures and the C-weighted Sound Exposure Levels (CSEL) for 43 near steady supersonic flights of the above United States Air Force and United States Navy aircraft. This report describes the measured database (BOOMFILE) that contains sonic boom signatures and overpressures, aircraft tracking, and local weather data. These measured data highlight the major influences on sonic boom propagation and generation. The data from this study show that a constant offset of 26 from the peak overpressure expressed in dB gives a good estimate of the CSEL of a sonic boom.

  2. Advection fog formation and aerosols produced by combustion-originated air pollution

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Liaw, G. S.; Vaughan, O. H., Jr.

    1980-01-01

    The way in which pollutants produced by the photochemical reaction of NO(X) and SO(X) affect the quality of the human environment through such phenomena as the formation of advection fog is considered. These pollutants provide the major source of condensation nuclei for the formation of fog in highways, airports and seaports. Results based on the monodisperse, multicomponent aerosol model show that: (1) condensation nuclei can grow and form a dense fog without the air having attained supersaturation; (2) the mass concentration range for NO(X) is one-third that of SO(X); and (3) the greater the mass concentration, the particle concentration, and the radius of condensation nuclei, the denser the fog that is formed.

  3. Light Transmission Fluctuations from Extended Air Showers Produced by Cosmic-Rays and Gamma-Rays

    NASA Astrophysics Data System (ADS)

    Taylor, Stuart

    Cosmic-ray and gamma-ray experiments that use the atmosphere as a calorimeter, such as the High Resolution Fly's Eye (HiRes) and the Telescope Array (TA), require understanding the transmission of the light from the air shower of particles produced by the cosmic-ray or gamma-ray striking the atmosphere. To better understand the scattering and transmission of light to the detectors, HiRes measures light from different calibrated sources. We compare scattered light from laser shots a few kilometers away from the two HiRes detectors with direct light from stable portable light sources placed a few meters in front of the phototubes. We use two HiRes detectors to study and isolate contributions to fluctuations of the measured light. These contributions include fluctuations in the source intensity, the night sky background, scattering and transmission of the laser beam, the phototubes and electronics, and photostatistics. N o rth Mirror Fields of View

  4. Laser Cladding to Improve Oxidation Behavior of Air Plasma-Sprayed Ni-20Cr Coating on Stainless Steel Substrate

    NASA Astrophysics Data System (ADS)

    Rauf, M. Mudassar; Shahid, Muhammad; Nusair Khan, A.; Mehmood, K.

    2015-09-01

    Air plasma-sprayed Ni-20Cr coating on stainless steel (AISI-304) substrate was re-melted using CO2 laser to remove the inherent defects, i.e., porosity, splat boundaries, and oxides of air plasma-sprayed coating. The (1) uncoated, (2) air plasma-sprayed, and (3) laser-re-melted specimens were exposed to cyclic oxidation at 900 °C for a hundred cycles run. The oxidation products were characterized using XRD and SEM. Weight changes were determined after every 4th cycle; Uncoated samples showed severe oxidation indicated by substantial weight loss, whereas air plasma-coated samples demonstrated noticeable weight gain. However, oxidation resistance of laser-cladded samples was found to be significantly improved as the samples showed negligible weight change; porosity within the coating was minimized with an improvement in interface quality causing reduction in delamination damage.

  5. Surface, electrical and mechanical modifications of PMMA after implantation with laser produced iron plasma ions

    NASA Astrophysics Data System (ADS)

    Ahmed, Qazi Salman; Bashir, Shazia; Jalil, Sohail Abdul; Shabbir, Muhammad Kaif; Mahmood, Khaliq; Akram, Mahreen; Khalid, Ayesha; Yaseen, Nazish; Arshad, Atiqa

    2016-07-01

    Laser Produced Plasma (LPP) was employed as an ion source for the modifications in surface, electrical and mechanical properties of poly methyl (methacrylate) PMMA. For this purpose Nd:YAG laser (532 nm, 6 ns, 10 Hz) at a fluence of 12.7 J/cm2 was employed to generate Fe plasma. The fluence and energy measurements of laser produced Fe plasma ions were carried out by employing Thomson Parabola Technique in the presence of magnetic field strength of 0.5 T, using CR-39 as Solid State Nuclear Track Detector (SSNTD). It has been observed that ion fluence ejecting from ablated plasma was maximum at an angle of 5° with respect to the normal to the Fe target surface. PMMA substrates were irradiated with Fe ions of constant energy of 0.85 MeV at various ion fluences ranging from 3.8 × 106 ions/cm2 to 1.8 × 108 ions/cm2 controlled by varying laser pulses from 3000 to 7000. Optical microscope and Scanning Electron Microscope (SEM) were utilized for the analysis of surface features of irradiated PMMA. Results depicted the formation of chain scission, crosslinking, dendrites and star like structures. To explore the electrical behavior, four probe method was employed. The electrical conductivity of ion irradiated PMMA was increased with increasing ion fluence. The surface hardness was measured by shore D hardness tester and results showed the monotonous increment in surface hardness with increasing ion fluence. The increasing trend of surface hardness and electrical conductivity with increasing Fe ion fluence has been well correlated with the surface morphology of ion implanted PMMA. The temperature rise of PMMA surface due to Fe ion irradiation is evaluated analytically and comes out to be in the range of 1.72 × 104 to 1.82 × 104 K. The values of total Linear Energy Transfer (LET) or stopping power of 0.8 MeV Fe ions in PMMA is 61.8 eV/Å and their range is 1.34 μm evaluated by SRIM simulation.

  6. Interferometric and schlieren characterization of the plasmas and shock wave dynamics during laser-triggered discharge in atmospheric air

    SciTech Connect

    Wei, Wenfu; Li, Xingwen Wu, Jian; Yang, Zefeng; Jia, Shenli; Qiu, Aici

    2014-08-15

    This paper describes our efforts to reveal the underlying physics of laser-triggered discharges in atmospheric air using a Mach-Zehnder interferometer and schlieren photography. Unlike the hemispherical shock waves that are produced by laser ablation, bell-like morphologies are observed during laser-triggered discharges. Phase shifts are recovered from the interferograms at a time of 1000 ns by the 2D fast Fourier transform method, and then the values of the refractive index are deduced using the Abel inversion. An abundance of free electrons is expected near the cathode surface. The schlieren photographs visualize the formation of stagnation layers at ∼600 ns in the interaction zones of the laser- and discharge-produced plasmas. Multiple reflected waves are observed at later times with the development of shock wave propagations. Estimations using the Taylor-Sedov self-similar solution indicated that approximately 45.8% and 51.9% of the laser and electrical energies are transferred into the gas flow motions, respectively. Finally, numerical simulations were performed, which successfully reproduced the main features of the experimental observations, and provided valuable insights into the plasma and shock wave dynamics during the laser-triggered discharge.

  7. Interferometric and schlieren characterization of the plasmas and shock wave dynamics during laser-triggered discharge in atmospheric air

    NASA Astrophysics Data System (ADS)

    Wei, Wenfu; Li, Xingwen; Wu, Jian; Yang, Zefeng; Jia, Shenli; Qiu, Aici

    2014-08-01

    This paper describes our efforts to reveal the underlying physics of laser-triggered discharges in atmospheric air using a Mach-Zehnder interferometer and schlieren photography. Unlike the hemispherical shock waves that are produced by laser ablation, bell-like morphologies are observed during laser-triggered discharges. Phase shifts are recovered from the interferograms at a time of 1000 ns by the 2D fast Fourier transform method, and then the values of the refractive index are deduced using the Abel inversion. An abundance of free electrons is expected near the cathode surface. The schlieren photographs visualize the formation of stagnation layers at ˜600 ns in the interaction zones of the laser- and discharge-produced plasmas. Multiple reflected waves are observed at later times with the development of shock wave propagations. Estimations using the Taylor-Sedov self-similar solution indicated that approximately 45.8% and 51.9% of the laser and electrical energies are transferred into the gas flow motions, respectively. Finally, numerical simulations were performed, which successfully reproduced the main features of the experimental observations, and provided valuable insights into the plasma and shock wave dynamics during the laser-triggered discharge.

  8. Atmospheric pressure He-air plasma jet: Breakdown process and propagation phenomenon

    NASA Astrophysics Data System (ADS)

    Begum, Asma; Laroussi, Mounir; Pervez, Mohammad Rasel

    2013-06-01

    In this paper He-discharge (plasma jet/bullet) in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES) and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet is not isolated from the input voltage along its propagation path. The discharge propagation speed, the electron density and the local and average electric field distribution along the plasma jet axis predicted from the experimental results are in good agreement with the data predicted by numerical simulation of the streamer propagation presented in different literatures. The ionization phenomenon of the discharge predicts the key ionization parameters, such as speed, peak electric field in the front, and electron density. The maximum local electric field measured by OES is 95 kV/cm at 1.3 cm of the jet axis, and average EF measured by probe is 24 kV/cm at the same place of the jet. The average and local electron density estimated are in the order of 1011 cm-3 and it reaches to the maximum of 1012 cm-3.

  9. Studies of air, water, and ethanol vapor atmospheric pressure plasmas for antimicrobial applications.

    PubMed

    Ferrell, James R; Bogovich, Erinn R; Lee, Nicholas R; Gray, Robert L; Pappas, Daphne D

    2015-06-25

    The generation of air-based plasmas under atmospheric plasma conditions was studied to assess their antimicrobial efficacy against commonly found pathogenic bacteria. The mixture of initial gases supplied to the plasma was found to be critical for the formation of bactericidal actives. The optimal gas ratio for bactericidal effect was determined to be 99% nitrogen and 1% oxygen, which led to a 99.999% reduction of a pathogenic strain of Escherichia coli on stainless steel surfaces. The experimental substrate, soil load on the substrate, flow rate of the gases, and addition of ethanol vapor all were found to affect antimicrobial efficacy of studied plasmas. Optical emission spectroscopy was used to identify the species that were present in the plasma bulk phase for multiple concentrations of nitrogen and oxygen ratios. The collected spectra indicate a unique series of bands present in the ultraviolet region of the electromagnetic spectrum that can be attributed to nitric oxide species known to be highly antimicrobial. This intense spectral profile dramatically changes as the concentration of nitrogen decreases.

  10. Studies of air, water, and ethanol vapor atmospheric pressure plasmas for antimicrobial applications.

    PubMed

    Ferrell, James R; Bogovich, Erinn R; Lee, Nicholas R; Gray, Robert L; Pappas, Daphne D

    2015-01-01

    The generation of air-based plasmas under atmospheric plasma conditions was studied to assess their antimicrobial efficacy against commonly found pathogenic bacteria. The mixture of initial gases supplied to the plasma was found to be critical for the formation of bactericidal actives. The optimal gas ratio for bactericidal effect was determined to be 99% nitrogen and 1% oxygen, which led to a 99.999% reduction of a pathogenic strain of Escherichia coli on stainless steel surfaces. The experimental substrate, soil load on the substrate, flow rate of the gases, and addition of ethanol vapor all were found to affect antimicrobial efficacy of studied plasmas. Optical emission spectroscopy was used to identify the species that were present in the plasma bulk phase for multiple concentrations of nitrogen and oxygen ratios. The collected spectra indicate a unique series of bands present in the ultraviolet region of the electromagnetic spectrum that can be attributed to nitric oxide species known to be highly antimicrobial. This intense spectral profile dramatically changes as the concentration of nitrogen decreases. PMID:25810273

  11. Laser produced plasma sources for nanolithography—Recent integrated simulation and benchmarking

    SciTech Connect

    Hassanein, A.; Sizyuk, T.

    2013-05-15

    Photon sources for extreme ultraviolet lithography (EUVL) are still facing challenging problems to achieve high volume manufacturing in the semiconductor industry. The requirements for high EUV power, longer optical system and components lifetime, and efficient mechanisms for target delivery have narrowed investigators towards the development and optimization of dual-pulse laser sources with high repetition rate of small liquid tin droplets and the use of multi-layer mirror optical system for collecting EUV photons. We comprehensively simulated laser-produced plasma sources in full 3D configuration using 10–50 μm tin droplet targets as single droplets as well as, for the first time, distributed fragmented microdroplets with equivalent mass. The latter is to examine the effects of droplet fragmentation resulting from the first pulse and prior to the incident second main laser pulse. We studied the dependence of target mass and size, laser parameters, and dual pulse system configuration on EUV radiation output and on atomic and ionic debris generation. Our modeling and simulation included all phases of laser target evolution: from laser/droplet interaction, energy deposition, target vaporization, ionization, plasma hydrodynamic expansion, thermal and radiation energy redistribution, and EUV photons collection as well as detail mapping of photons source size and location. We also simulated and predicted the potential damage to the optical mirror collection system from plasma thermal and energetic debris and the requirements for mitigating systems to reduce debris fluence. The debris effect on mirror collection system is analyzed using our three-dimensional ITMC-DYN Monte Carlo package. Modeling results were benchmarked against our CMUXE laboratory experimental studies for the EUV photons production and for debris and ions generation.

  12. Stable dense plasma jets produced at laser power densities around 1014 W/cm2

    NASA Astrophysics Data System (ADS)

    Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Ullschmied, J.; Krousky, E.; Masek, K.; Rohlena, K.; Skala, J.; Hora, H.

    2006-06-01

    The results of investigations are presented that are connected with defocused laser beam-planar target interaction. Following the very large focus laser-plasma interaction experiments on the Nova [H. T. Powell, J. A. Caird, J. E. Murray, and C. E. Thompson, 1991 ICF Annual Report UCRL-LR-105820-91, p. 163 (1991)] and GEKKO-XII [C. Yamanaka, Y. Kato, Y. Izawa, K. Yoshida, T. Yamanaka, T. Sasaki, T. Nakatsuka, J. Kuroda, and S. Nakai, IEEE J. Quantum Electron. QE-17, 1639 (1981)] lasers, as well as on the National Ignition Facility (NIF) laser [W. J. Hogan, E. I. Moses, B. E. Warner, M. S. Sorem, and J. M. Soures, Nucl. Fusion 41, 567 (2001)] with generation of high Mach number jets, this paper is devoted to similar jet generation with very detailed measurements of density profiles by using high-power lasers at large focus conditions. The experiment was carried out with target materials of different mass densities (Al, Cu, Ag, Ta, and Pb) using the Prague Asterix Laser System (PALS) iodine laser [K. Jungwirth, A. Cejnarova, L. Juha, B. Kralikowa, J. Krasa, E. Krousky, P. Krupickova, L. Laska, K. Masek, A. Prag, O. Renner, K. Rohlena, B. Rus, J. Skala, P. Straka, and J. Ullschmied, Phys. Plasmas 8, 2495 (2001)]. The investigations were conducted for the laser radiation energy of 100J at two wavelengths of 1.315 and 0.438μm (the first and third harmonics of laser radiation), pulse duration of 0.4ns, and a focal spot radius of 300μm. Most of the experimental data were obtained by means of a three-frame laser interferometer and an x-ray streak camera; the crater parameters were obtained by using the crater replica technique. These investigations have shown that stable dense plasma jets can be produced in a simple configuration of laser beam-planar target interaction, provided that a proper target material is used.

  13. Combinatorial plasma polymerization approach to produce thin films for testing cell proliferation.

    PubMed

    Antonini, V; Torrengo, S; Marocchi, L; Minati, L; Dalla Serra, M; Bao, G; Speranza, G

    2014-01-01

    Plasma enhanced physical vapor depositions are extensively used to fabricate substrates for cell culture applications. One peculiarity of the plasma processes is the possibility to deposit thin films with reproducible chemical and physical properties. In the present work, a combinatorial plasma polymerization process was used to deposit thin carbon based films to promote cell adhesion, in the interest of testing cell proliferation as a function of the substrate chemical properties. Peculiarity of the combinatorial approach is the possibility to produce in just one deposition experiment, a set of surfaces of varying chemical moieties by changing the precursor composition. A full characterization of the chemical, physical and thermodynamic properties was performed for each set of the synthesized surfaces. X-ray photoelectron spectroscopy was used to measure the concentration of carboxyl, hydroxyl and amine functional groups on the substrate surfaces. A perfect linear trend between polar groups' density and precursors' concentration was found. Further analyses reveled that also contact angles and the correspondent surface energies of all deposited thin films are linearly dependent on the precursor concentration. To test the influence of the surface composition on the cell adhesion and proliferation, two cancer cell lines were utilized. The cell viability was assessed after 24 h and 48 h of cell culture. Experiments show that we are able to control the cell adhesion and proliferation by properly changing the thin film deposition conditions i.e. the concentration and the kind of chemical moiety on the substrate surface. The results also highlight that physical and chemical factors of biomaterial surface, including surface hydrophobicity and free energy, chemical composition, and topography, can altered cell attachment.

  14. X-ray High-resolution Spectroscopy for Laser-produced Plasma

    NASA Astrophysics Data System (ADS)

    Barbato, F.; Scarpellini, D.; Malizia, A.; Gaudio, P.; Richetta, M.; Antonelli, L.

    The study of the emission spectrum gives information about the material generating the spectrum itself and the condition in which this is generated. The wavelength spectra lines are linked to the specific element and plasma conditions (electron temperature, density), while their shape is influenced by several physical effects like Stark and Doppler ones. In this work we study the X-ray emission spectra of a copper laser-produced plasma by using a spherical bent crystal spectrometer to measure the electron temperature. The facility used is the laser TVLPS, at the Tor Vergata University in Rome. It consists of a Nd:Glass source (in first harmonic - 1064 nm) whose pulse parameters are: 8 J in energy, time duration of 15 ns and a focal spot diameter of 200 μm. The adopted spectrometer is based on a spherical bent crystal of muscovite. The device combines the focusing property of a spherical mirror with the Bragg's law. This allows to obtain a great power resolution but a limited range of analysis. In our case the resolution is on average 80 eV. As it is well-known, the position of the detector on the Rowland's circle is linked to the specific spectral range which has been studied. To select the area to be investigated, we acquired spectra by means of a flat spectrometer. The selected area is centered on 8.88 Å. To calibrate the spectrum we wrote a ray-tracing MATLAB code, which calculates the detector alignment parameters and calibration curve. We used the method of line ratio to measure the electron temperature. This is possible because we assumed the plasma to be in LTE condition. The temperature value was obtained comparing the experimental one, given by the line ratio, with the theoretical one, preceded by FLYCHK simulations.

  15. Vacuum ultraviolet spectral emission properties of Ga, In and Sn droplet-based laser produced plasmas

    NASA Astrophysics Data System (ADS)

    Gambino, Nadia; Rollinger, Bob; Brandstätter, Markus; Abhari, Reza S.

    2016-08-01

    The Emission Spectra of gallium, indium and tin droplet-based laser produced plasmas are presented in the Vacuum Ultraviolet (VUV) emission range from 30 nm to 160 nm. The Ga ion transitions are investigated in detail as a function of background pressure level and laser irradiance. Different wavelength emission regions were detected according to the level of background gas. At short wavelengths (i.e. 30-50 nm) the line emission from the higher charge states is reduced with increasing pressure, while at longer wavelengths (i.e. 100-160 nm) the trend is inverted, as the plasma emission intensity of the lower charge states increases with higher background gas pressure level. The emitted lines are fitted with Voigt profiles to determine the electron density. The electron temperature is obtained from a fit based on the Planck distribution. These estimations are then used to identify the relevant processes that lead to the different charge state emissions as a function of background gas. Langmuir Probe measurements are also reported for evaluating the ion kinetic energy as a function of background gas. The gallium spectra are calibrated in units of spectral radiance, together with spectra from indium and tin. This calibration allows absolute power estimations from the light source in the VUV region. The presented experimental results are relevant as fundamental plasma emission spectroscopic measurements in an almost unexplored wavelength region as well as for applications such as Extreme Ultraviolet Lithography to determine the so-called Out-of-Band (OoB) radiation emission and for metrology applications for future inspection tools.

  16. Structure and properties of commercially pure titanium nitrided in the plasma of a low-pressure gas discharge produced by a PINK plasma generator

    NASA Astrophysics Data System (ADS)

    Ivanov, Yu F.; Akhmadeev, Yu H.; Lopatin, I. V.; Petrikova, E. A.; Krysina, V.; Koval, N. N.

    2015-11-01

    The paper analyzes the surface structure and properties of commercially pure VT1-0 titanium nitrided in the plasma of a low-pressure gas discharge produced by a PINK plasma generator. The analysis demonstrates that the friction coefficient of the nitrided material decreases more than four times and its wear resistance and microhardness increases more than eight and three times, respectively. The physical mechanisms responsible for the enhancement of strength and tribological properties of the material are discussed.

  17. Kinetics of ion and prompt electron emission from laser-produced plasma

    SciTech Connect

    Farid, N.; Harilal, S. S.; Hassanein, A.; Ding, H.

    2013-07-15

    We investigated ion emission dynamics of laser-produced plasma from several elements, comprised of metals and non-metals (C, Al, Si, Cu, Mo, Ta, W), under vacuum conditions using a Faraday cup. The estimated ion flux for various targets studied showed a decreasing tendency with increasing atomic mass. For metals, the ion flux is found to be a function of sublimation energy. A comparison of temporal ion profiles of various materials showed only high-Z elements exhibited multiple structures in the ion time of flight profile indicated by the observation of higher peak kinetic energies, which were absent for low-Z element targets. The slower ions were seen regardless of the atomic number of target material propagated with a kinetic energy of 1–5 keV, while the fast ions observed in high-Z materials possessed significantly higher energies. A systematic study of plasma properties employing fast photography, time, and space resolved optical emission spectroscopy, and electron analysis showed that there existed different mechanisms for generating ions in laser ablation plumes. The origin of high kinetic energy ions is related to prompt electron emission from high-Z targets.

  18. Plasma waves produced by an ion beam: Observations by the VLF experiment on Porcupine

    NASA Astrophysics Data System (ADS)

    Jones, D.

    1980-06-01

    Results are presented from the VLF electric field experiments flown on Porcupine flights F3 and F4, which also had ejectable xenon ion sources. The xenon ion beam was found to produce plasma instabilities whose frequencies could be linked to the local proton gyrofrequency. The main energy in the instabilities lies at 3kHz for events when the Xe+ source is close to the rocket, and at 7kHz when the source is farther away. Theory predicts that these frequencies should be the lower-hybrid-resonance and this implies that Xe+ is the dominant ion in the first case and that it is the ambient plasma that dominates later. There is no discernable antenna spin-modulation during the Xe events which indicates that the wave k-vectors are not unidirectional. A theory is cited based on the setting up of the proton cyclotron harmonic waves by the Xe+ or 0+ cyclotron harmonic waves. The second Xe+ event on both flights exhibited an, as yet, unexplained harmonic structure related to half the local proton gyrofrequency.

  19. Gaussian energy distribution of fast ions emitted by laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Krása, J.

    2013-05-01

    The analysis of ion collector signals with the use of a time-of-fight signal function derived from a shifted Maxwell-Boltzmann velocity distribution is used to quantify the ion characteristics as the ion temperature and velocity of centre-of-mass motion of groups of ionized species constituting the ablated plasma. The analysis is also focused on velocity and energy distributions derived from the signal of a time-of-flight detector taking into account the underlying principle of sensor operation. The energy Maxwell spectra of ions are compared with the Gauss distribution with respect to the ratio of the centre-of-mass energy of ions to their temperature. The difference threshold between the Gauss and energy Maxwell spectra is determined via the limited validity of the basic relationship between spreads in energy and time-of-flight spectra ½ΔE/E = Δt/t. The analysis of velocity spectrum of fast ions emitted by Ti plasma produced with 300 ps, kJ-class iodine laser operating at PALS facility shows that ion bursts consist of almost monoenergetic ion beams.

  20. Neutral cluster debris dynamics in droplet-based laser-produced plasma sources

    NASA Astrophysics Data System (ADS)

    Hudgins, Duane; Gambino, Nadia; Rollinger, Bob; Abhari, Reza

    2016-05-01

    The neutral cluster debris dynamics of a droplet-based laser-produced plasma is studied experimentally and analytically. Experiments were done imaging the debris with a high-speed shadowgraph system and using image processing to determine the droplet debris mean radial velocity \\overline{V} dependence on laser pulse irradiance E e. The data shows a power law dependence between the mean radial debris velocity and the incident irradiance giving \\overline{V}\\propto E\\text{e}n with n≈ 0.65 . A scaled analytical model was derived modeling the plasma ablation pressure on the droplet surface as the primary momentum exchange mechanism between the unablated droplet material and the laser pulse. The relationship between droplet debris trajectory and the droplet alignment with the laser was quantified analytically. The derived analytical model determines that the neutral cluster debris trajectory for an ablated droplet is a function of the laser profile f L, the droplet diameter D and the axial misalignment h between the laser axis and the droplet center. The analytical calculations from these models were found to be in good agreement with the measurements. This analysis has practical significance for understanding ablated droplet debris, droplet deformation by laser pulsing, and droplet breakup from very short timescale shocks.

  1. Thermophysical property measurement at high temperatures by laser-produced plasmas

    SciTech Connect

    Kim, Y.W.

    1993-05-01

    Excitation by a high-power laser pulse of a material surface generates a sequence of plasma, fluid flow, and acoustic events. These are well separated in time, and their detection and analysis can lead to determination of material properties of the condensed phase target. We have developed a new methodology for real-time determination of molten metal composition by time-resolved spectroscopy of laser-produced plasmas (LPP). If the laser pulse is shaped in such a way that the movement of the bulk surface due to evaporation is kept in pace with the thermal diffusion front advancing into the interior of the target, the LPP plume becomes representative of the bulk in elemental composition. In addition, the mass loss due to LPP ablation is very well correlated with the thermal diffusivity of the target matter. For several elemental solid specimens, we show that the product of the ablation thickness and heat of formation is proportional to the thermal diffusivity per unit molecular weight. Such measurements can be extended to molten metal specimens if the mass loss by ablation, density, heat of formation, and molecular weight can be determined simultaneously. The results from the solid specimen and the progress with a levitation-assisted molten metal experiment are presented.

  2. Magnetic reconnection in high-energy-density laser-produced plasmas

    SciTech Connect

    Fox, W.; Bhattacharjee, A.; Germaschewski, K.

    2012-05-15

    Recently, novel experiments on magnetic reconnection have been conducted in laser-produced plasmas in a high-energy-density regime. Individual plasma bubbles self-generate toroidal, mega-gauss-scale magnetic fields through the Biermann battery effect. When multiple bubbles are created at small separation, they expand into one another, driving reconnection of this field. Reconnection in the experiments was reported to be much faster than allowed by both Sweet-Parker, and even Hall-MHD theories, when normalized to the nominal magnetic fields self-generated by single bubbles. Through particle-in-cell simulations (both with and without a binary collision operator), we model the bubble interaction at parameters and geometry relevant to the experiments. This paper discusses in detail the reconnection regime of the laser-driven experiments and reports the qualitative features of simulations. We find substantial flux-pileup effects, which boost the relevant magnetic field for reconnection in the current sheet. When this is accounted for, the normalized reconnection rates are much more in line with standard two-fluid theory of reconnection. At the largest system sizes, we additionally find that the current sheet is prone to breakup into plasmoids.

  3. Simulation of particle velocity in a laser-produced tin plasma extreme ultraviolet source

    SciTech Connect

    Masnavi, Majid; Nakajima, Mitsuo; Horioka, Kazuhiko; Araghy, Homaira Parchamy; Endo, Akira

    2011-06-15

    In connection with fast heating in a laser produced plasma (LPP) extreme ultraviolet (EUV) source, the superheating behavior of bulk tin (Sn) at high heating rates is investigated. A constant temperature and pressure molecular dynamics simulation using modified Lennard-Jones and Coulomb potentials suitable for studying the liquid structure of Sn is employed in order to derive the caloric curves of the solid and liquid phases. The results have shown transient effects on the phase transitions. Superheating is observed during the melting and vaporizing processes. The velocity distribution of Sn particles against typical laser fluence in a LPP EUV light source has been numerically investigated using a simplified method including a one-dimensional, two-temperature, molecular dynamics, and steady-state ionization model. In the framework of our model, it was found that ejected Sn particles have a maximum velocity on the order of 10 to 40 km/s in plasma created using a nanosecond pre-pulse neodymium-doped yttrium aluminum garnet (Nd:YAG, 1.06 {mu}m) laser in EUV lithography experiments.

  4. High average power, highly brilliant laser-produced plasma source for soft X-ray spectroscopy.

    PubMed

    Mantouvalou, Ioanna; Witte, Katharina; Grötzsch, Daniel; Neitzel, Michael; Günther, Sabrina; Baumann, Jonas; Jung, Robert; Stiel, Holger; Kanngiesser, Birgit; Sandner, Wolfgang

    2015-03-01

    In this work, a novel laser-produced plasma source is presented which delivers pulsed broadband soft X-radiation in the range between 100 and 1200 eV. The source was designed in view of long operating hours, high stability, and cost effectiveness. It relies on a rotating and translating metal target and achieves high stability through an on-line monitoring device using a four quadrant extreme ultraviolet diode in a pinhole camera arrangement. The source can be operated with three different laser pulse durations and various target materials and is equipped with two beamlines for simultaneous experiments. Characterization measurements are presented with special emphasis on the source position and emission stability of the source. As a first application, a near edge X-ray absorption fine structure measurement on a thin polyimide foil shows the potential of the source for soft X-ray spectroscopy. PMID:25832284

  5. Potential effects of Plasma on the Development of Laser Produced Craters

    SciTech Connect

    Batani, Dimitri; Desai, Tara; Rossetti, Stefano; Lucchini, Gianni

    2006-04-07

    Laser ablation and crater formation have been studied on a copper target using a 10 Hz, Nd:YAG laser system delivering pulses up to 100 mJ in 40 ps with a flux on target F{<=} 5000 J/cm2. Crater dimensions were measured using optical microscope or SEM (Scanning Electron Microscope). In order to understand the process of crater formation, we considered various theoretical models present in the literature and revised them taking into account the occurrence of plasma phenomena, which are important at the intensities used in this experiment. We also compared our experimental results with other results obtained at the PALS laboratory, using a 0.44 {mu}m wavelength laser and much higher laser intensities. Finally we explore the possibility of extending the information derived from laser produced craters to other types of craters.

  6. Time-resolved soft x-ray spectra from laser-produced Cu plasma

    SciTech Connect

    Cone, K. V.; Baldis, H. A.; Dunn, J.; May, M. J.; Schneider, M. B.; Scott, H. A.; Purvis, M. A.

    2012-10-15

    The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated by a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800-1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in two-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target.

  7. Time-resolved soft x-ray spectra from laser-produced Cu plasma.

    PubMed

    Cone, K V; Baldis, H A; Dunn, J; May, M J; Purvis, M A; Schneider, M B; Scott, H A

    2012-10-01

    The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated by a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800-1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in two-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target.

  8. Time-resolved soft x-ray spectra from laser-produced Cu plasma

    SciTech Connect

    Cone, K V; Dunn, J; Baldis, H A; May, M J; Purvis, M A; Scott, H A; Schneider, M B

    2012-05-02

    The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated from a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800-1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in 2-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target.

  9. High average power, highly brilliant laser-produced plasma source for soft X-ray spectroscopy

    SciTech Connect

    Mantouvalou, Ioanna; Grötzsch, Daniel; Neitzel, Michael; Günther, Sabrina; Baumann, Jonas; Kanngießer, Birgit; Witte, Katharina; Jung, Robert; Stiel, Holger; Sandner, Wolfgang

    2015-03-15

    In this work, a novel laser-produced plasma source is presented which delivers pulsed broadband soft X-radiation in the range between 100 and 1200 eV. The source was designed in view of long operating hours, high stability, and cost effectiveness. It relies on a rotating and translating metal target and achieves high stability through an on-line monitoring device using a four quadrant extreme ultraviolet diode in a pinhole camera arrangement. The source can be operated with three different laser pulse durations and various target materials and is equipped with two beamlines for simultaneous experiments. Characterization measurements are presented with special emphasis on the source position and emission stability of the source. As a first application, a near edge X-ray absorption fine structure measurement on a thin polyimide foil shows the potential of the source for soft X-ray spectroscopy.

  10. Magnetic properties of Co-Zr-B magnets produced by spark plasma sintering method

    SciTech Connect

    Saito, Tetsuji Akiyama, Tomoya

    2014-05-07

    Magnets of Co-Zr-B, one of the permanent magnetic compounds without rare-earth elements, were successfully produced by the spark plasma sintering method. The resultant Co-Zr-B magnets had high densities of 92%–96% and consisted mainly of the Co{sub x}Zr (x ≈ 5) phase. The coercivity of the Co-Zr-B magnets was highly dependent on the consolidation temperature and the boron content. The highest maximum energy product of 6.0 MGOe, with a remanence of 6.4 kG and the coercivity of 4.0 kOe, was achieved by the Co{sub 80}Zr{sub 18}B{sub 2} magnets consolidated at 873 K.

  11. Features in the ion emission of Cu, Al, and C plasmas produced by ultrafast laser ablation

    NASA Astrophysics Data System (ADS)

    Kelly, T. J.; Butler, T.; Walsh, N.; Hayden, P.; Costello, J. T.

    2015-12-01

    The bi-modal nature of charge integrated ion kinetic energy distributions, which result from ultrafast laser produced plasmas, is discussed in this paper. A negatively biased Faraday cup was used as a charge collector to measure ion distributions from three different solid targets that had been irradiated with an ultrafast laser in the fluence range 0.1 -1 J/cm 2 . A bi-modal time of flight distribution is found for all three targets (C, Al, and Cu). In the case of the metallic targets (Al and Cu), high- and low-kinetic energy peaks exhibit quite different dependencies on laser fluence, whereas for the semi-metallic target (C), both peaks scale similarly with ultrafast laser fluence. The results are discussed within the framework of a one dimensional capacitor model resulting in ion acceleration.

  12. Calibration of a Flat Field Soft X-ray Grating Spectrometer for Laser Produced Plasmas

    SciTech Connect

    Park, J; Brown, G V; Schneider, M B; Baldis, H A; Beiersdorfer, P; Cone, K V; Kelley, R L; Kilbourne, C A; Magee, E; May, M J; Porter, F S

    2010-05-12

    We have calibrated the x ray response of a variable line spaced grating spectrometer, known as the VSG, at the Fusion and Astrophysics Data and Diagnostic Calibration Facility at the Lawrence Livermore National Laboratory (LLNL). The VSG has been developed to diagnose laser produced plasmas, such as those created at the Jupiter Laser Facility and the National Ignition Facility at LLNL, and at both the Omega and Omega EP lasers at University of Rochester's Laboratory for Laser Energetics. The bandwidth of the VSG spans the range from {approx} 6 to 60 {angstrom}. The calibration results present here include the VSG's dispersion and quantum efficiency. The dispersion is determined by measuring the x rays emitted from hydrogen-like and helium-like ions of carbon, nitrogen, oxygen, neon, and aluminum. The quantum efficiency is calibrated to an accuracy of 30% or better by normalizing the x ray intensities recorded by the VSG to those simultaneously recorded by an x ray microcalorimeter spectrometer.

  13. High average power, highly brilliant laser-produced plasma source for soft X-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Mantouvalou, Ioanna; Witte, Katharina; Grötzsch, Daniel; Neitzel, Michael; Günther, Sabrina; Baumann, Jonas; Jung, Robert; Stiel, Holger; Kanngießer, Birgit; Sandner, Wolfgang

    2015-03-01

    In this work, a novel laser-produced plasma source is presented which delivers pulsed broadband soft X-radiation in the range between 100 and 1200 eV. The source was designed in view of long operating hours, high stability, and cost effectiveness. It relies on a rotating and translating metal target and achieves high stability through an on-line monitoring device using a four quadrant extreme ultraviolet diode in a pinhole camera arrangement. The source can be operated with three different laser pulse durations and various target materials and is equipped with two beamlines for simultaneous experiments. Characterization measurements are presented with special emphasis on the source position and emission stability of the source. As a first application, a near edge X-ray absorption fine structure measurement on a thin polyimide foil shows the potential of the source for soft X-ray spectroscopy.

  14. Systems and methods for imaging using radiation from laser produced plasmas

    DOEpatents

    Renard-Le Galloudec, Nathalie; Cowan, Thomas E.; Sentoku, Yasuhiko; Rassuchine, Jennifer

    2009-06-30

    In particular embodiments, the present disclosure provides systems and methods for imaging a subject using radiation emitted from a laser produced plasma generating by irradiating a target with a laser. In particular examples, the target includes at least one radiation enhancing component, such as a fluor, cap, or wire. In further examples, the target has a metal layer and an internal surface defining an internal apex, the internal apex of less than about 15 .mu.m, such as less than about 1 .mu.m. The targets may take a variety of shapes, including cones, pyramids, and hemispheres. Certain aspects of the present disclosure provide improved imaging of a subject, such as improved medical images of a radiation dose than typical conventional methods and systems.

  15. Experimental study of wood downdraft gasification for an improved producer gas quality through an innovative two-stage air and premixed air/gas supply approach.

    PubMed

    Jaojaruek, Kitipong; Jarungthammachote, Sompop; Gratuito, Maria Kathrina B; Wongsuwan, Hataitep; Homhual, Suwan

    2011-04-01

    This study conducted experiments on three different downdraft gasification approaches: single stage, conventional two-stage, and an innovative two-stage air and premixed air/gas supply approach. The innovative two-stage approach has two nozzle locations, one for air supply at combustion zone and the other located at the pyrolysis zone for supplying the premixed gas (air and producer gas). The producer gas is partially bypassed to mix with air and supplied to burn at the pyrolysis zone. The result shows that producer gas quality generated by the innovative two-stage approach improved as compared to conventional two-stage. The higher heating value (HHV) increased from 5.4 to 6.5 MJ/Nm(3). Tar content in producer gas reduced to less than 45 mg/Nm(3). With this approach, gas can be fed directly to an internal combustion engine. Furthermore, the gasification thermal efficiency also improved by approximately 14%. The approach gave double benefits on gas qualities and energy savings. PMID:21292477

  16. Experimental study of wood downdraft gasification for an improved producer gas quality through an innovative two-stage air and premixed air/gas supply approach.

    PubMed

    Jaojaruek, Kitipong; Jarungthammachote, Sompop; Gratuito, Maria Kathrina B; Wongsuwan, Hataitep; Homhual, Suwan

    2011-04-01

    This study conducted experiments on three different downdraft gasification approaches: single stage, conventional two-stage, and an innovative two-stage air and premixed air/gas supply approach. The innovative two-stage approach has two nozzle locations, one for air supply at combustion zone and the other located at the pyrolysis zone for supplying the premixed gas (air and producer gas). The producer gas is partially bypassed to mix with air and supplied to burn at the pyrolysis zone. The result shows that producer gas quality generated by the innovative two-stage approach improved as compared to conventional two-stage. The higher heating value (HHV) increased from 5.4 to 6.5 MJ/Nm(3). Tar content in producer gas reduced to less than 45 mg/Nm(3). With this approach, gas can be fed directly to an internal combustion engine. Furthermore, the gasification thermal efficiency also improved by approximately 14%. The approach gave double benefits on gas qualities and energy savings.

  17. Kinetic studies of NO formation in pulsed air-like low-pressure dc plasmas

    NASA Astrophysics Data System (ADS)

    Hübner, M.; Gortschakow, S.; Guaitella, O.; Marinov, D.; Rousseau, A.; Röpcke, J.; Loffhagen, D.

    2016-06-01

    The kinetics of the formation of NO in pulsed air-like dc plasmas at a pressure of 1.33 mbar and mean currents between 50 and 150 mA of discharge pulses with 5 ms duration has been investigated both experimentally and by self-consistent numerical modelling. Using time-resolved quantum cascade laser absorption spectroscopy, the densities of NO, NO2 and N2O have been measured in synthetic air as well as in air with 0.8% of NO2 and N2O, respectively. The temporal evolution of the NO density shows four distinct phases during the plasma pulse and the early afterglow in the three gas mixtures that were used. In particular, a steep density increase during the ignition phase and after termination of the discharge current pulse has been detected. The NO concentration has been found to reach a constant value of 0.57× {{10}14}~\\text{molecules}~\\text{c}{{\\text{m}}-3} , 1.05× {{10}14}~\\text{molecules}~\\text{c}{{\\text{m}}-3} , and 1.3× {{10}14}~\\text{molecules}~\\text{c}{{\\text{m}}-3} for mean plasma currents of 50 mA, 100 mA and 150 mA, respectively, in the afterglow. The measured densities of NO2 and N2O in the respective mixture decrease exponentially during the plasma pulse and remain almost constant in the afterglow, especially where the admixture of NO2 has a remarkable impact on the NO production during the ignition. The numerical results of the coupled solution of a set of rate equations for the various heavy particles and the time-dependent Boltzmann equation of the electrons agree quite well with the experimental findings for the different air-like plasmas. The main reaction processes have been analysed on the basis of the model calculations and the remaining differences between the experiment and modelling especially during the afterglow are discussed.

  18. A high-power low-temperature air plasma generator with a divergent channel of the output electrode

    NASA Astrophysics Data System (ADS)

    Gadzhiev, M. Kh.; Isakaev, E. Kh.; Tyuftyaev, A. S.; Yusupov, D. I.

    2016-01-01

    We have developed and studied a powerful high-enthalpy (H ≥ 20 kJ/g) air plasma jet generator with a divergent channel of the output electrode, which belongs to the class of dc plasmatrons with a thermionic cathode. The plasma generator possesses an efficiency of about 80% and ensures the formation of slightly divergent (2± = 12°) plasma jet with diameter D = 50 mm and a mass-average temperature of 6000-9000 K.

  19. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  20. Kinetic mechanism of molecular energy transfer and chemical reactions in low-temperature air-fuel plasmas.

    PubMed

    Adamovich, Igor V; Li, Ting; Lempert, Walter R

    2015-08-13

    This work describes the kinetic mechanism of coupled molecular energy transfer and chemical reactions in low-temperature air, H2-air and hydrocarbon-air plasmas sustained by nanosecond pulse discharges (single-pulse or repetitive pulse burst). The model incorporates electron impact processes, state-specific N(2) vibrational energy transfer, reactions of excited electronic species of N(2), O(2), N and O, and 'conventional' chemical reactions (Konnov mechanism). Effects of diffusion and conduction heat transfer, energy coupled to the cathode layer and gasdynamic compression/expansion are incorporated as quasi-zero-dimensional corrections. The model is exercised using a combination of freeware (Bolsig+) and commercial software (ChemKin-Pro). The model predictions are validated using time-resolved measurements of temperature and N(2) vibrational level populations in nanosecond pulse discharges in air in plane-to-plane and sphere-to-sphere geometry; temperature and OH number density after nanosecond pulse burst discharges in lean H(2)-air, CH(4)-air and C(2)H(4)-air mixtures; and temperature after the nanosecond pulse discharge burst during plasma-assisted ignition of lean H2-mixtures, showing good agreement with the data. The model predictions for OH number density in lean C(3)H(8)-air mixtures differ from the experimental results, over-predicting its absolute value and failing to predict transient OH rise and decay after the discharge burst. The agreement with the data for C(3)H(8)-air is improved considerably if a different conventional hydrocarbon chemistry reaction set (LLNL methane-n-butane flame mechanism) is used. The results of mechanism validation demonstrate its applicability for analysis of plasma chemical oxidation and ignition of low-temperature H(2)-air, CH(4)-air and C(2)H(4)-air mixtures using nanosecond pulse discharges. Kinetic modelling of low-temperature plasma excited propane-air mixtures demonstrates the need for development of a more accurate

  1. Kinetic mechanism of molecular energy transfer and chemical reactions in low-temperature air-fuel plasmas.

    PubMed

    Adamovich, Igor V; Li, Ting; Lempert, Walter R

    2015-08-13

    This work describes the kinetic mechanism of coupled molecular energy transfer and chemical reactions in low-temperature air, H2-air and hydrocarbon-air plasmas sustained by nanosecond pulse discharges (single-pulse or repetitive pulse burst). The model incorporates electron impact processes, state-specific N(2) vibrational energy transfer, reactions of excited electronic species of N(2), O(2), N and O, and 'conventional' chemical reactions (Konnov mechanism). Effects of diffusion and conduction heat transfer, energy coupled to the cathode layer and gasdynamic compression/expansion are incorporated as quasi-zero-dimensional corrections. The model is exercised using a combination of freeware (Bolsig+) and commercial software (ChemKin-Pro). The model predictions are validated using time-resolved measurements of temperature and N(2) vibrational level populations in nanosecond pulse discharges in air in plane-to-plane and sphere-to-sphere geometry; temperature and OH number density after nanosecond pulse burst discharges in lean H(2)-air, CH(4)-air and C(2)H(4)-air mixtures; and temperature after the nanosecond pulse discharge burst during plasma-assisted ignition of lean H2-mixtures, showing good agreement with the data. The model predictions for OH number density in lean C(3)H(8)-air mixtures differ from the experimental results, over-predicting its absolute value and failing to predict transient OH rise and decay after the discharge burst. The agreement with the data for C(3)H(8)-air is improved considerably if a different conventional hydrocarbon chemistry reaction set (LLNL methane-n-butane flame mechanism) is used. The results of mechanism validation demonstrate its applicability for analysis of plasma chemical oxidation and ignition of low-temperature H(2)-air, CH(4)-air and C(2)H(4)-air mixtures using nanosecond pulse discharges. Kinetic modelling of low-temperature plasma excited propane-air mixtures demonstrates the need for development of a more accurate

  2. Influence of air pressure on the performance of plasma synthetic jet actuator

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    Plasma synthetic jet actuator (PSJA) has a wide application prospect in the high-speed flow control field for its high jet velocity. In this paper, the influence of the air pressure on the performance of a two-electrode PSJA is investigated by the schlieren method in a large range from 7 kPa to 100 kPa. The energy consumed by the PSJA is roughly the same for all the pressure levels. Traces of the precursor shock wave velocity and the jet front velocity vary a lot for different pressures. The precursor shock wave velocity first decreases gradually and then remains at 345 m/s as the air pressure increases. The peak jet front velocity always appears at the first appearance of a jet, and it decreases gradually with the increase of the air pressure. A maximum precursor shock wave velocity of 520 m/s and a maximum jet front velocity of 440 m/s are observed at the pressure of 7 kPa. The averaged jet velocity in one period ranges from 44 m/s to 54 m/s for all air pressures, and it drops with the rising of the air pressure. High velocities of the precursor shock wave and the jet front indicate that this type of PSJA can still be used to influence the high-speed flow field at 7 kPa. Project supported by the National Natural Science Foundation of China (Grant Nos. 51407197, 51522606, 51336011, 91541120, and 11472306).

  3. Effect of non-thermal air atmospheric pressure plasma jet treatment on gingival wound healing

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Hwan; Choi, Eun-Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2016-02-01

    Non-thermal atmospheric pressure plasmas have been applied in the biomedical field for the improvement of various cellular activities. In dentistry, the healing of gingival soft tissue plays an important role in health and aesthetic outcomes. While the biomedical application of plasma has been thoroughly studied in dentistry, a detailed investigation of plasma-mediated human gingival fibroblast (HGF) migration for wound healing and its underlying biological mechanism is still pending. Therefore, the aim of this study is to apply a non-thermal air atmospheric pressure plasma jet (NTAAPPJ) to HGF to measure the migration and to reveal the underlying biological mechanisms involved in the migration. After the characterization of NTAAPPJ by optical emission spectroscopy, the adherent HGF was treated with NTAAPPJ or air with a different flow rate. Cell viability, lipid peroxidation, migration, intracellular reactive oxygen species (ROS), and the expression of migration-related genes (EGFR, PAK1, and MAPK3) were investigated. The level of statistical significance was set at 0.05. NTAAPPJ and air treatment with a flow rate of 250–1000 standard cubic centimetres per minute (sccm) for up to 30 s did not induce significant decreases in cell viability or membrane damage. A significant increase in the migration of mitomycin C-treated HGF was observed after 30 s of NTAAPPJ treatment compared to 30 s air-only treatment, which was induced by high levels of intracellular reactive oxygen species (ROS). An increase in migration-related gene expression and EGFR activation was observed following NTAAPPJ treatment in an air flow rate-dependent manner. This is the first report that NTAAPPJ treatment induces an increase in HGF migration without changing cell viability or causing membrane damage. HGF migration was related to an increase in intracellular ROS, changes in the expression of three of the migration-related genes (EGFR, PAK1, and MAPK1), and EGFR activation. Therefore

  4. Effect of non-thermal air atmospheric pressure plasma jet treatment on gingival wound healing

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Hwan; Choi, Eun-Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2016-02-01

    Non-thermal atmospheric pressure plasmas have been applied in the biomedical field for the improvement of various cellular activities. In dentistry, the healing of gingival soft tissue plays an important role in health and aesthetic outcomes. While the biomedical application of plasma has been thoroughly studied in dentistry, a detailed investigation of plasma-mediated human gingival fibroblast (HGF) migration for wound healing and its underlying biological mechanism is still pending. Therefore, the aim of this study is to apply a non-thermal air atmospheric pressure plasma jet (NTAAPPJ) to HGF to measure the migration and to reveal the underlying biological mechanisms involved in the migration. After the characterization of NTAAPPJ by optical emission spectroscopy, the adherent HGF was treated with NTAAPPJ or air with a different flow rate. Cell viability, lipid peroxidation, migration, intracellular reactive oxygen species (ROS), and the expression of migration-related genes (EGFR, PAK1, and MAPK3) were investigated. The level of statistical significance was set at 0.05. NTAAPPJ and air treatment with a flow rate of 250-1000 standard cubic centimetres per minute (sccm) for up to 30 s did not induce significant decreases in cell viability or membrane damage. A significant increase in the migration of mitomycin C-treated HGF was observed after 30 s of NTAAPPJ treatment compared to 30 s air-only treatment, which was induced by high levels of intracellular reactive oxygen species (ROS). An increase in migration-related gene expression and EGFR activation was observed following NTAAPPJ treatment in an air flow rate-dependent manner. This is the first report that NTAAPPJ treatment induces an increase in HGF migration without changing cell viability or causing membrane damage. HGF migration was related to an increase in intracellular ROS, changes in the expression of three of the migration-related genes (EGFR, PAK1, and MAPK1), and EGFR activation. Therefore

  5. Physical and chemical properties of dust produced in a N{sub 2}-CH{sub 4} RF plasma discharge

    SciTech Connect

    Ouni, F.; Alcouffe, G.; Szopa, C.; Carrasco, N.; Cernogora, G.; Adande, G.; Thissen, R.; Quirico, E.; Brissaud, O.; Schmitz-Afonso, I.; Laprevote, O.

    2008-09-07

    Titan's atmospheric chemistry is simulated using a Capacitively Coupled Plasma discharge produced in a N{sub 2}-CH{sub 4} mixture. The produced solid particles are analysed ex-situ. Chemical properties are deduced from: elemental composition, FTIR and LTQ-Orbitrap mass spectrometer. Optical properties are deduced from reflectivity in visible and IR range.

  6. Photoionization capable, extreme and vacuum ultraviolet emission in developing low temperature plasmas in air

    NASA Astrophysics Data System (ADS)

    Stephens, J.; Fierro, A.; Beeson, S.; Laity, G.; Trienekens, D.; Joshi, R. P.; Dickens, J.; Neuber, A.

    2016-04-01

    Experimental observation of photoionization capable extreme ultraviolet and vacuum ultraviolet emission from nanosecond timescale, developing low temperature plasmas (i.e. streamer discharges) in atmospheric air is presented. Applying short high voltage pulses enabled the observation of the onset of plasma formation exclusively by removing the external excitation before spark development was achieved. Contrary to the common assumption that radiative transitions from the b{{}1}{{\\Pi}u} (Birge-Hopfield I) and b{{}\\prime 1}Σu+ (Birge-Hopfield II) singlet states of N2 are the primary contributors to photoionization events, these results indicate that radiative transitions from the c{{4\\prime}1}Σu+ (Carroll-Yoshino) singlet state of N2 are dominant in developing low temperature plasmas in air. In addition to c{}4\\prime transitions, photoionization capable transitions from atomic and singly ionized atomic oxygen were also observed. The inclusion of c{{4\\prime}1}Σu+ transitions into a statistical photoionization model coupled with a fluid model enabled streamer growth in the simulation of positive streamers.

  7. Influence of a Static Magnetic Field on Laser Induced Tungsten Plasma in Air

    NASA Astrophysics Data System (ADS)

    Wu, Ding; Liu, Ping; Sun, Liying; Hai, Ran; Ding, Hongbin

    2016-04-01

    In this work, laser induced tungsten plasma has been investigated in the absence and presence of 0.6 T static transverse magnetic field at atmospheric pressure in air. The spectroscopic characterization of laser induced tungsten plasma was experimentally studied using space-resolved emission spectroscopy. The atomic emission lines of tungsten showed a significant enhancement in the presence of a magnetic field, while the ionic emission lines of tungsten presented little change. Temporal variation of the optical emission lines of tungsten indicated that the atomic emission time in the presence of a magnetic field was longer than that in the absence of a magnetic field, while no significant changes occurred for the ionic emission time. The spatial resolution of optical emission lines of tungsten demonstrated that the spatial distribution of atoms and ions were separated. The influence of a magnetic field on the spatial distribution of atoms was remarkable, whereas the spatial distribution of ions was little influenced by the magnetic field. The different behaviors between ions and atoms with and without magnetic field in air were related to the various atomic processes especially the electrons and ions recombination process during the plasma expansion and cooling process.

  8. The impact of air-fuel mixture composition on SI engine performance during natural gas and producer gas combustion

    NASA Astrophysics Data System (ADS)

    Przybyła, G.; Postrzednik, S.; Żmudka, Z.

    2016-09-01

    The paper summarizers results of experimental tests of SI engine fuelled with gaseous fuels such as, natural gas and three mixtures of producer gas substitute that simulated real producer gas composition. The engine was operated under full open throttle and charged with different air-fuel mixture composition (changed value of air excess ratio). The spark timing was adjusted to obtain maximum brake torque (MBT) for each fuel and air-fuel mixture. This paper reports engine indicated performance based on in-cylinder, cycle resolved pressure measurements. The engine performance utilizing producer gas in terms of indicated efficiency is increased by about 2 percentage points when compared to fuelling with natural gas. The engine power de-rating when producer gas is utilized instead the natural gas, varies from 24% to 28,6% under stoichiometric combustion conditions. For lean burn (λ=1.5) the difference are lower and varies from 22% to 24.5%.

  9. Rayleigh-Taylor-Induced Electromagnetic Fields in Laser-Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Manuel, Mario J.-E.

    Spontaneous electromagnetic fields can be important to the dynamic evolution of a plasma by directing heat flow as well as providing additional pressures on the conducting fluids through the Lorentz force. Electromagnetic fields are predicted to affect fluid behavior during the core-collapse of supernovae through generation of fields due to hydrodynamic instabilities. In the coronae of stars, self-generated magnetic fields lead to filamentary structure in the hot plasma. Recent experiments by Gregori et al. investigated sources of protogalactic magnetic fields generated by laser-produced shock waves. In inertial confinement fusion experiments, self-generated electromagnetic fields can also play a role and have recently become of great interest to the community. Present day laser facilities provide a unique opportunity to study spontaneous field-generation in these extreme environments under controlled conditions. Instability-induced electromagnetic fields were investigated using a novel monoenergetic-proton radiography system. Fusion protons generated by an 'exploding-pusher' implosion were used to probe laser-irradiated plastic foils with various preimposed surface perturbations. Imaging protons are sensitive to electromagnetic fields and density modulations in the plasma through the Lorentz force and Coulomb collisions, respectively. Corresponding x-ray radiographs of these targets provided mass density distributions and Coulomb effects on protons were assessed using a Monte Carlo code written using the Geant4 framework. Proton fluence distributions were recorded on CR-39 detectors and Fourier analyzed to infer path-integrated field strengths. Rayleigh-Taylor (RT) growth of preimposed surface perturbations generated magnetic fields by the RT-induced Biermann battery and were measured for the first time. Good data were obtained during linear growth and when compared to ideal calculations, demonstrated that field diffusion near the source played an important role

  10. Laser Produced Plasmas as a Source of Ions, Protons and X-rays

    NASA Astrophysics Data System (ADS)

    Stefanuik, Robert

    The work presented in this thesis is primarily focused on the use of a laser produced plasma as a source of protons, ions and X-rays. It explores high impact applications of both high power ultrafast lasers and nanosecond lasers. Section 1 gives a general introduction to the physics governing the experiments and the lasers in the following sections. Section 2 describes all the laser systems used in this thesis. Section 3 is covers two different experiments involving the generation of X-rays from a laser produced plasma. Section 4 describes a laser accelerated proton experiment conducted in the Center for Plasma Research in Queens University Belfast, using the TARANIS laser system. In this experiment 13 MeV protons were accelerated from10 μm gold foil targets into a sample of BK-7 glass. The interaction of the protons with the glass were observed by taking spatially resolved images of the transient opacity induced by the protons interacting with the BK-7 Glass and an optical probe beam. These spatially resolved images are presented in Section 4.3. Section 5 describes the refurbishment of the 1-m normal incidence VUV spectrometer. It describes the replacement of a photographic plate based detection system with a linear CCD array. The CCD array can detect the VUV radiation through a sodium salicylate phosphor coating which emits at 410 nm on interacting with VUV radiation. Different phosphors are compared in terms of sensitivity and ease of coating and the grounds for choosing sodium salicylate are explained. The adaptations to the spectrometer to use the linear CCD array are described and the details on calibrating the spectrometer are explained. Finally, Section 6 describes a set of spectroscopic experiments which use the refurbished 1-m normal incidence spectrometer. First Section 6.2 describes a repeat of the photoabsorption of indium and indium plus which was conducted previously on the spectrometer. This was designed as a proof of principle of the working of

  11. 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.

  12. ADI-FDTD modeling of microwave plasma discharges in air towards fully three-dimensional simulations

    NASA Astrophysics Data System (ADS)

    Kourtzanidis, Konstantinos; Rogier, François; Boeuf, Jean-Pierre

    2015-10-01

    Plasma formation and propagation during microwave breakdown has been extensively studied during the last decades. Numerical modeling of the strong coupling between the high frequency electromagnetic waves and the plasma is still a challenging topic due to the different time and space scales involved. In this article, an Alternative Direction Implicit (ADI) formulation of the Finite Difference Time Domain method for solving Maxwell's equations coupled with a simplified plasma model via the electric current is being proposed, leading to a significant reduction of the computational cost as the CFL criterion for stability of the FDTD method is being removed. An energy estimate has been used to prove the unconditional stability of the ADI-FDTD leapfrog scheme as well as its coupled formulation. The computational efficiency and accuracy of this approach has been studied in a simplified case. The proposed method is applied and validated in two dimensional microwave breakdown in air while its computational efficiency allows for fully three dimensional simulations, an important step for understanding the complex nature and evolution of a microwave plasma discharge and its possible applicability as an aerodynamic flow control method.

  13. Atmospheric pressure discharge plasma decomposition for gaseous air contaminants -- Trichlorotrifluoroethane and trichloroethylene

    SciTech Connect

    Oda, Tetsuji; Yamashita, Ryuichi; Takahashi, Tadashi; Masuda, Senichi

    1996-03-01

    The decomposition performance of gaseous environmental destructive contaminants in air by using atmospheric pressure discharged plasma including the surface discharge induced plasma chemical processing (SPCP) was examined. The main contaminants tested were chlorofluorocarbon (CFC-113) and trichloroethylene, typically. The discharge exciting frequency range studied was wide--50 Hz to 50 kHz. Results showed the low frequency discharge requires high voltage to inject high electric power in the gas and to decompose the contaminants. A Gas Chromatograph Mass Spectrometer was used to analyze discharge products of dense CFC-113 or trichloroethylene. Among the detected products were HCl, CClFO, and CHCl{sub 3}. Two different electrode configurations; the silent discharge (coaxial) electrode and the coil-electrode were also tested and compared to each other as a gas reactor.

  14. Factors affecting the microstructural stability and durability of thermal barrier coatings fabricated by air plasma spraying

    SciTech Connect

    Helminiak, M A; Yanar, N M; Pettit, F S; Taylor, T A; Meier, G H

    2012-10-01

    The high-temperature behavior of high-purity, low-density (HP-LD) air plasma sprayed (APS) thermal barrier coatings (TBCs) with NiCoCrAlY bond coats deposited by argon-shrouded plasma spraying is described. The high purity yttria-stabilized zirconia resulted in top coats which are highly resistant to sintering and transformation from the metastable tetragonal phase to the equilibrium mixture of monoclinic and cubic phases. The thermal conductivity of the as-processed TBC is low but increases during high temperature exposure even before densification occurs. The porous topcoat microstructure also resulted in good spallation resistance during thermal cycling. The actual failure mechanisms of the APS coatings were found to depend on topcoat thickness, topcoat density, and the thermal cycle frequency. The failure mechanisms are described and the durability of the HP-LD coatings is compared with that of state-of-the-art electron beam physical vapor deposition TBCs.

  15. Air plasma gasification of RDF as a prospective method for reduction of carbon dioxide emission

    NASA Astrophysics Data System (ADS)

    Bratsev, A. N.; Kumkova, I. I.; Kuznetsov, V. A.; Popov, V. E.; Shtengel', S. V.; Ufimtsev, A. A.

    2011-03-01

    Waste disposal dumps are one of sources of carbonic gas penetration in the atmosphere. The waste is treated into RDF (refuse-derived fuel) and used in boilers for electric power or heat generation for decrease in carbonic gas emissions in the atmosphere. In industry power stations on the basis of the combined cycle have the highest efficiency of burning. The paper deals with the application of an air-plasma gasifier using the down draft scheme of RDF transformation into synthesis gas, which afterwards can be used in the combined cycle. Results of calculations of the process characteristics for various RDF compositions are presented. The advantage of the plasma method in comparison with autothermal one is shown. Experimental data are shown.

  16. Characterization of magnetically confined low-pressure plasmas produced by an electromagnetic field in argon-acetylene mixtures

    NASA Astrophysics Data System (ADS)

    Makdessi, G. Al; Margot, J.; Clergereaux, R.

    2016-10-01

    Dust particles formation was investigated in magnetically confined low-pressure plasma produced in argon-acetylene mixtures. The plasma characteristics were measured in order to identify the species involved in the dust particles formation. Their dependence on the operating conditions including magnetic field intensity, acetylene fraction in the gas mixture and operating pressure was examined. In contrast with noble gases, in the presence of acetylene, the electron temperature increases with the magnetic field intensity, indicating additional charged particles losses in the plasma. Indeed, in these conditions, larger hydrocarbon ions are produced leading to the formation of dust particles in the plasma volume. The observed dependence of positive ion mass distribution and density and relative negative ion density on the operating parameters suggests that the dust particles are formed through different pathways, where negative and positive ions are both involved in the nucleation.

  17. Silent Discharge Plasma Technology for the Treatment of Air Toxics and Other Applications

    SciTech Connect

    Rosocha, Louis A.; Chase, Peter J.; Gross, Michael P.

    1998-09-21

    Under this CRADA, the Los Alamos National Laboratory (LANL) and High Mesa Technologies, Inc. (HMT) carried out a joint project on the development of the silent discharge plasma (SDP) technology for the treatment of hazardous air pollutants and other hazardous or toxic chemicals. The project had two major components: a technology-demonstration part and a scale-up and commercialization part. In the first part, a small-scale, mobile SDP plasma processor, which was being developed under a CRADA with the Electric Power Research Institute (EPRI) was the mobile equipment was modified for higher capacity service and employed for an innovative remediation technologies demonstration on soil-vapor extraction off-gases at the McClellan Air Force Base near Sacramento, CA. The performance of the SDP system for the variety of volatile organic compounds (VOCs) encountered at the McClellan site was sufficiently promising to the project HMT and LANL worked together to formulate a scale-up strategy and commercialization/manufacturing plan, and to design a prototype scaled-up SDP unit. HMT and LANL are now in the final stages of completing a licensing agreement for the technology and HMT is in the process of raising funds to engineer and manufacture commercial prototype SDP equipment focused on stack-gas emissions control and environmental remediation. HMT, in collaboration with another Northern New Mexico business, Coyote Aerospace, has also been successful in receiving a Phase I Small Business Innovative Research (SBIR) award from the Army Research Office to develop, design, and construct a small non-thermal plasma reactor for laboratory studies ("Non-Thermal Plasma Reactor for Control of Fugitive Emissions of Toxic Gases")

  18. Conversion of air mixture with ethanol and water vapors in nonequilibrium gas-discharge plasma

    NASA Astrophysics Data System (ADS)

    Shchedrin, A. I.; Levko, D. S.; Chernyak, V. Ya.; Yukhimenko, V. V.; Naumov, V. V.

    2009-05-01

    In search for an alternative fuel for internal combustion engines, we have studied the possibility of obtaining molecular hydrogen via the conversion of air mixture with ethanol and water vapors in a new plasma reactor. It is shown that, in agreement with experimental data, the H2 concentration is a linear function of the discharge current and decreases with increasing gas flow rate in the interelectrode gap. It is established that the proposed approach provides higher molecular hydrogen concentrations as compared to those achieved with other methods.

  19. Formation of the characteristics of ion emission from a laser-produced plasma in the presence of a conducting diaphragm

    SciTech Connect

    Bykovskii, Yurii A; Konyukhov, I Yu; Peklenkov, V D; Ponomarenko, D V

    2000-08-31

    The effect of electrical diaphragm-target coupling on the formation of ion component characteristics of a laser-produced plasma is considered. When the target and the diaphragm are insulated from each other and are under a floating potential, a high-energy ion peak is observed and the integral number of ions and their multiplicity increase compared to the case when the target and the diaphragm are connected and grounded. (interaction of laser radiation with matter. laser plasma)

  20. Spectroscopy of reactive species produced by low-energy atmospheric-pressure plasma on conductive target material surface

    NASA Astrophysics Data System (ADS)

    Yamada, Hiromasa; Sakakita, Hajime; Kato, Susumu; Kim, Jaeho; Kiyama, Satoru; Fujiwara, Masanori; Itagaki, Hirotomo; Okazaki, Toshiya; Ikehara, Sanae; Nakanishi, Hayao; Shimizu, Nobuyuki; Ikehara, Yuzuru

    2016-10-01

    A method for blood coagulation using low-energy atmospheric-pressure plasma (LEAPP) is confirmed as an alternative procedure to reduce tissue damage caused by heat. Blood coagulation using LEAPP behaves differently depending on working gas species; helium is more effective than argon in promoting fast coagulation. To analyse the difference in reactive species produced by helium and argon plasma, spectroscopic measurements were conducted without and with a target material. To compare emissions, blood coagulation experiments using LEAPP for both plasmas were performed under almost identical conditions. Although many kinds of reactive species such as hydroxyl radicals and excited nitrogen molecules were observed with similar intensity in both plasmas, intensities of nitrogen ion molecules and nitric oxide molecules were extremely strong in the helium plasma. It is considered that nitrogen ion molecules were mainly produced by penning ionization by helium metastable. Near the target, a significant increase in the emissions of reactive species is observed. There is a possibility that electron acceleration was induced in a local electric field formed on the surface. However, in argon plasma, emissions from nitrogen ion were not measured even near the target surface. These differences between the two plasmas may be producing the difference in blood coagulation behaviour. To control the surrounding gas of the plasma, a gas-component-controllable chamber was assembled. Filling the chamber with O2/He or N2/He gas mixtures selectively produces either reactive oxygen species or reactive nitrogen species. Through selective treatments, this chamber would be useful in studying the effects of specific reactive species on blood coagulation.

  1. Traveling-wave laser-produced-plasma energy source for photoionization laser pumping and lasers incorporating said

    DOEpatents

    Sher, Mark H.; Macklin, John J.; Harris, Stephen E.

    1989-09-26

    A traveling-wave, laser-produced-plasma, energy source used to obtain single-pass gain saturation of a photoionization pumped laser. A cylindrical lens is used to focus a pump laser beam to a long line on a target. Grooves are cut in the target to present a surface near normal to the incident beam and to reduce the area, and hence increase the intensity and efficiency, of plasma formation.

  2. Radiofrequency plasma assisted exfoliation and reduction of large-area graphene oxide platelets produced by a mechanical transfer process

    NASA Astrophysics Data System (ADS)

    Cardinali, Marta; Valentini, Luca; Fabbri, Paola; Kenny, Josè M.

    2011-05-01

    We present a method to produce extended few layer flakes of reduced graphene oxide starting from bulk graphene oxide platelets using Ar plasma treatment at room temperature of mechanically exfoliated platelets. Multilayer graphene oxide platelets transferred to a silicon wafer by micromechanical cleavage were thinned in a controllable and reproducible way by plasma treatment to achieve few-layer reduced graphene sheets without the use of heating or wet chemistry approaches.

  3. Increased Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

    DOEpatents

    Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

    1997-07-08

    High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

  4. Increasing Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

    DOEpatents

    Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

    1999-08-24

    High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

  5. Measurements of ion temperature and flow of pulsed plasmas produced by a magnetized coaxial plasma gun device using an ion Doppler spectrometer

    NASA Astrophysics Data System (ADS)

    Kitagawa, Y.; Sakuma, I.; Iwamoto, D.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    It is important to know surface damage characteristics of plasma-facing component materials during transient heat and particle loads such as type I ELMs. A magnetized coaxial plasma gun (MCPG) device has been used as transient heat and particle source in ELM simulation experiments. Characteristics of pulsed plasmas produced by the MCPG device play an important role for the plasma material interaction. In this study, ion temperature and flow velocity of pulsed He plasmas were measured by an ion Doppler spectrometer (IDS). The IDS system consists of a light collection system including optical fibers, 1m-spectrometer and a 16 channel photomultiplier tube (PMT) detector. The IDS system measures the width and Doppler shift of HeII (468.58 nm) emission line with the time resolution of 1 μs. The Doppler broadened and shifted spectra were measured with 45 and 135 degree angles with respect to the plasmoid traveling direction. The observed emission line profile was represented by sum of two Gaussian components to determine the temperature and flow velocity. The minor component at around the wavelength of zero-velocity was produced by the stationary plasma. As the results, the ion velocity and temperature were 68 km/s and 19 eV, respectively. Thus, the He ion flow energy is 97 eV. The observed flow velocity agrees with that measured by a time of flight technique.

  6. Development and Evaluation of an Externally Air-Cooled Low-Flow torch and the Attenuation of Space Charge and Matrix Effects in Inductively Coupled Plasma Mass Spectrometry

    SciTech Connect

    Praphairaksit, N.

    2000-09-12

    An externally air-cooled low-flow torch has been constructed and successfully demonstrated for applications in inductively coupled plasma mass spectrometry (ICP-MS). The torch is cooled by pressurized air flowing at {approximately}70 L/min through a quartz air jacket onto the exterior of the outer tube. The outer gas flow rate and operating RF forward power are reduced considerably. Although plasmas can be sustained at the operating power as low as 400 W with a 2 L/min of outer gas flow, somewhat higher power and outer gas flows are advisable. A stable and analytical useful plasma can be obtained at 850 W with an outer gas flow rate of {approximately}4 L/min. Under these conditions, the air-cooled plasma produces comparable sensitivities, doubly charged ion ratios, matrix effects and other analytical merits as those produced by a conventional torch while using significantly less argon and power requirements. Metal oxide ion ratios are slightly higher with the air-cooled plasma but can be mitigated by reducing the aerosol gas flow rate slightly with only minor sacrifice in analyte sensitivity. A methodology to alleviate the space charge and matrix effects in ICP-MS has been developed. A supplemental electron source adapted from a conventional electron impact ionizer is added to the base of the skimmer. Electrons supplied from this source downstream of the skimmer with suitable amount and energy can neutralize the positive ions in the beam extracted from the plasma and diminish the space charge repulsion between them. As a result, the overall ion transmission efficiency and consequent analyte ion sensitivities are significantly improved while other important analytical aspects, such as metal oxide ion ratio, doubly charged ion ratio and background ions remain relatively unchanged with the operation of this electron source. This technique not only improves the ion transmission efficiency but also minimizes the matrix effects drastically. The matrix-induced suppression

  7. Efficient new process for the desulfurization of mixtures of air and hydrogen sulfide via a dielectric barrier discharge plasma

    NASA Astrophysics Data System (ADS)

    Dahle, S.

    2015-10-01

    The efficient removal of hydrogen sulfide, H2S, from streams of H2S in air via a dielectric barrier discharge (DBD) plasma has been investigated using a quadrupole mass spectrometer. A suitable plasma device with a reservoir for storing sorbent powder of various kinds within the plasma region was constructed. Plasma treatments of gas streams with high concentrations of hydrogen sulfide in air yielded a removal of more than 98% of the initial hydrogen sulfide and a deposition of sulfur at the surface of the dielectric, while small amounts of sulfur dioxide were generated. The presence of calcium carbonate within the plasma region of the DBD device resulted in the removal of over 99% of the initial hydrogen sulfide content and the removal of 98% of the initial sulfur dioxide impurities from the gas mixture.

  8. A comparative study of the characteristics of French fries produced by deep fat frying and air frying.

    PubMed

    Teruel, Maria del Rocio; Gordon, Michael; Linares, Maria Belen; Garrido, Maria Dolores; Ahromrit, Araya; Niranjan, Keshavan

    2015-02-01

    Air frying is being projected as an alternative to deep fat frying for producing snacks such as French fries. In air frying, the raw potato sections are essentially heated in hot air containing fine oil droplets, which dehydrates the potato and attempts to impart the characteristics of traditionally produced French fries, but with a substantially lower level of fat absorbed in the product. The aim of this research is to compare: (1) the process dynamics of air frying with conventional deep fat frying under otherwise similar operating conditions, and (2) the products formed by the 2 processes in terms of color, texture, microstructure, calorimetric properties, and sensory characteristics. Although, air frying produced products with a substantially lower fat content but with similar moisture contents and color characteristics, it required much longer processing times, typically 21 min in relation to 9 min in the case of deep fat frying. The slower evolution of temperature also resulted in lower rates of moisture loss and color development reactions. Differential scanning calorimetry (DSC) studies revealed that the extent of starch gelatinization was also lower in the case of air fried product. In addition, the 2 types of frying also resulted in products having significantly different texture and sensory characteristics. PMID:25619624

  9. A comparative study of the characteristics of French fries produced by deep fat frying and air frying.

    PubMed

    Teruel, Maria del Rocio; Gordon, Michael; Linares, Maria Belen; Garrido, Maria Dolores; Ahromrit, Araya; Niranjan, Keshavan

    2015-02-01

    Air frying is being projected as an alternative to deep fat frying for producing snacks such as French fries. In air frying, the raw potato sections are essentially heated in hot air containing fine oil droplets, which dehydrates the potato and attempts to impart the characteristics of traditionally produced French fries, but with a substantially lower level of fat absorbed in the product. The aim of this research is to compare: (1) the process dynamics of air frying with conventional deep fat frying under otherwise similar operating conditions, and (2) the products formed by the 2 processes in terms of color, texture, microstructure, calorimetric properties, and sensory characteristics. Although, air frying produced products with a substantially lower fat content but with similar moisture contents and color characteristics, it required much longer processing times, typically 21 min in relation to 9 min in the case of deep fat frying. The slower evolution of temperature also resulted in lower rates of moisture loss and color development reactions. Differential scanning calorimetry (DSC) studies revealed that the extent of starch gelatinization was also lower in the case of air fried product. In addition, the 2 types of frying also resulted in products having significantly different texture and sensory characteristics.

  10. Light Transmission From Extended Air Showers Produced By Cosmic-Rays and Gamma-Rays

    NASA Astrophysics Data System (ADS)

    Taylor, S. F.; Abu-Zayyad, T.; Belov, K.; Cao, Z.; Chen, G.; Jui, C. C. H.; Kieda, D. B.; Matthews, J. N.; Salamon, M.; Sokolsky, P. V.; Smith, J. D.; Sommers, P.; Springer, R. W.; Stokes, B. T.; Thomas, S. B.; Wiencke, L. R.; Matthews, J. A. J.; Clay, R. W.; Dawson, B. R.; Simpson, K.; Bells, J.; Boyer, J.; Knapp, B.; Song, B. H.; Zhang, X. Z.; SDSS Collaboration; High Resolution Fly's Eye Collaboration; Telescope Array/U. Tokyo Collaboration

    1999-05-01

    Cosmic-ray and gamma-ray experiments that use the atmosphere as a calorimeter, such as the High Resolution Fly's Eye (HiRes) and the Telescope Array (TA), require understanding the transmission of the light from the air shower of particles produced by the cosmic-ray or gamma-ray striking the atmosphere. To better understand the scattering and transmission of light to the detectors, HiRes measures light from different calibrated sources. We compare scattered light from laser shots a few kilometers away from the two HiRes detectors, with direct light from stable portable light sources placed a few meters in front of the phototubes. We use two HiRes detectors to study and isolate contributions to fluctuations of the measured light. These contributions include fluctuations in the source intensity, the night sky background, scattering and transmission of the laser beam, the phototubes and electronics, and photostatistics. The High Resolution Fly's Eye Collaboration gratefully acknowledges the support of the US National Science Foundation, DOE, the US Army's Dugway Proving Grounds, and the support of our member universities.

  11. Characteristics of extreme ultraviolet emission from mid-infrared laser-produced rare-earth Gd plasmas.

    PubMed

    Higashiguchi, Takeshi; Li, Bowen; Suzuki, Yuhei; Kawasaki, Masato; Ohashi, Hayato; Torii, Shuichi; Nakamura, Daisuke; Takahashi, Akihiko; Okada, Tatsuo; Jiang, Weihua; Miura, Taisuke; Endo, Akira; Dunne, Padraig; O'Sullivan, Gerry; Makimura, Tetsuya

    2013-12-30

    We characterize extreme ultraviolet (EUV) emission from mid-infrared (mid-IR) laser-produced plasmas (LPPs) of the rare-earth element Gd. The energy conversion efficiency (CE) and the spectral purity in the mid-IR LPPs at λL = 10.6 μm were higher than for solid-state LPPs at λL = 1.06 μm, because the plasma produced is optically thin due to the lower critical density, resulting in a CE of 0.7%. The peak wavelength remained fixed at 6.76 nm for all laser intensities studied. Plasma parameters at a mid-IR laser intensity of 1.3×10(11) W/cm(2) was also evaluated by use of the hydrodynamic simulation code to produce the EUV emission at 6.76 nm. PMID:24514779

  12. Plume splitting and rebounding in a high-intensity CO{sub 2} laser induced air plasma

    SciTech Connect

    Chen Anmin; Jiang Yuanfei; Liu Hang; Jin Mingxing; Ding Dajun

    2012-07-15

    The dynamics of plasma plume formed by high-intensity CO{sub 2} laser induced breakdown of air at atmospheric pressure is investigated. The laser wavelength is 10.6 {mu}m. Measurements were made using 3 ns gated fast photography as well as space and time resolved optical emission spectroscopy. The behavior of the plasma plume was studied with a laser energy of 3 J and 10 J. The results show that the evolution of the plasma plume is very complicated. The splitting and rebounding of the plasma plume is observed to occur early in the plumes history.

  13. Manganese oxide octahedral molecular sieve K-OMS-2 as catalyst in post plasma-catalysis for trichloroethylene degradation in humid air.

    PubMed

    Nguyen Dinh, M T; Giraudon, J-M; Vandenbroucke, A M; Morent, R; De Geyter, N; Lamonier, J-F

    2016-08-15

    The total oxidation of trichloroethylene (TCE) in air at low relative humidity (RH=10%) in the presence of CO2 (520ppmv) was investigated in function of energy density using an atmospheric pressure negative DC luminescent glow discharge combined with a cryptomelane catalyst positioned downstream of the plasma reactor at a temperature of 150°C. When using Non-Thermal Plasma (NTP) alone, it is found a low COx (x=1-2) yield in agreement with the detection of gaseous polychlorinated by-products in the outlet stream as well as ozone which is an harmful pollutant. Introduction of cryptomelane enhanced trichloroethylene removal, totally inhibited plasma ozone formation and increased significantly the COx yield. The improved performances of the hybrid system were mainly ascribed to the total destruction of plasma generated ozone on cryptomelane surface to produce active oxygen species. Consequently these active oxygen species greatly enhanced the abatement of the plasma non-reacted TCE and completely destroyed the hazardous plasma generated polychlorinated intermediates. The facile redox of Mn species associated with oxygen vacancies and mobility as well as the textural properties of the catalyst might also contribute as a whole to the efficiency of the process. PMID:27107238

  14. Atmospheric pressure He-air plasma jet: Breakdown process and propagation phenomenon

    SciTech Connect

    Begum, Asma; Laroussi, Mounir; Pervez, Mohammad Rasel

    2013-06-15

    In this paper He-discharge (plasma jet/bullet) in atmospheric pressure air and its progression phenomenon has been studied experimentally using ICCD camera, optical emission spectroscopy (OES) and calibrated dielectric probe measurements. The repetitive nanosecond pulse has applied to a plasma pencil to generate discharge in the helium gas channel. The discharge propagation speed was measured from the ICCD images. The axial electric field distribution in the plasma jet is inferred from the optical emission spectroscopic data and from the probe measurement. The correlation between the jet velocities, jet length with the pulse duration is established. It shows that the plasma jet is not isolated from the input voltage along its propagation path. The discharge propagation speed, the electron density and the local and average electric field distribution along the plasma jet axis predicted from the experimental results are in good agreement with the data predicted by numerical simulation of the streamer propagation presented in different literatures. The ionization phenomenon of the discharge predicts the key ionization parameters, such as speed, peak electric field in the front, and electron density. The maximum local electric field measured by OES is 95 kV/cm at 1.3 cm of the jet axis, and average EF measured by probe is 24 kV/cm at the same place of the jet. The average and local electron density estimated are in the order of 10{sup 11} cm{sup -3} and it reaches to the maximum of 10{sup 12} cm{sup -3}.

  15. Improved Ethanol Production from Xylose by Candida shehatae Induced by Dielectric Barrier Discharge Air Plasma

    NASA Astrophysics Data System (ADS)

    Chen, Huixia; Xiu, Zhilong; Bai, Fengwu

    2014-06-01

    Xylose fermentation is essential for ethanol production from lignocellulosic biomass. Exposure of the xylose-fermenting yeast Candida shehatae (C. shehatae) CICC1766 to atmospheric pressure dielectric barrier discharge (DBD) air plasma yields a clone (designated as C81015) with stability, which exhibits a higher ethanol fermentation rate from xylose, giving a maximal enhancement in ethanol production of 36.2% compared to the control (untreated). However, the biomass production of C81015 is lower than that of the control. Analysis of the NADH (nicotinamide adenine dinucleotide)- and NADPH (nicotinamide adenine dinucleotide phosphate)-linked xylose reductases and NAD+-linked xylitol dehydrogenase indicates that their activities are enhanced by 34.1%, 61.5% and 66.3%, respectively, suggesting that the activities of these three enzymes are responsible for improving ethanol fermentation in C81015 with xylose as a substrate. The results of this study show that DBD air plasma could serve as a novel and effective means of generating microbial strains that can better use xylose for ethanol fermentation.

  16. Electromagnetic wave attenuation measurements in a ring-shaped inductively coupled air plasma

    NASA Astrophysics Data System (ADS)

    Wei, Xiaolong; Xu, Haojun; Li, Jianhai; Lin, Min; Su; Chen

    2015-05-01

    An aerocraft with the surface, inlet and radome covered large-area inductive coupled plasma (ICP) can attenuate its radar echo effectively. The shape, thickness, and electron density ( N e ) distribution of ICP are critical to electromagnetic wave attenuation. In the paper, an air all-quartz ICP generator in size of 20 × 20 × 7 cm3 without magnetic confinement is designed. The discharge results show that the ICP is amorphous in E-mode and ring-shaped in H-mode. The structure of ICP stratifies into core region and edge halo in H-mode, and its width and thickness changes from power and pressure. Such phenomena are explained by the distribution of RF magnetic field, the diffusion of negative ions plasma and the variation of skin depth. In addition, the theoretical analysis shows that the N e achieves nearly uniform within the electronegative core and sharply steepens in the edge. The N e of core region is diagnosed by microwave interferometer under varied conditions (pressure in range of 10-50 Pa, power in 300-700 W). Furthermore, the electromagnetic wave attenuation measurements were carried out with the air ICP in the frequencies of 4-5 GHz. The results show that the interspaced ICP is still effective to wave attenuation, and the wave attenuation increases with the power and pressure. The measured attenuation is approximately in accordance with the calculation data of finite-different time-domain simulations.

  17. A large-area diffuse air discharge plasma excited by nanosecond pulse under a double hexagon needle-array electrode.

    PubMed

    Liu, Zhi-Jie; Wang, Wen-Chun; Yang, De-Zheng; Wang, Sen; Zhang, Shuai; Tang, Kai; Jiang, Peng-Chao

    2014-01-01

    A large-area diffuse air discharge plasma excited by bipolar nanosecond pulse is generated under a double hexagon needle-array electrode at atmospheric pressure. The images of the diffuse discharge, electric characteristics, and the optical emission spectra emitted from the diffuse air discharge plasma are obtained. Based on the waveforms of pulse voltage and current, the power consumption, and the power density of the diffuse air discharge plasma are investigated under different pulse peak voltages. The electron density and the electron temperature of the diffuse plasma are estimated to be approximately 1.42×10(11) cm(-3) and 4.4 eV, respectively. The optical emission spectra are arranged to determine the rotational and vibrational temperatures by comparing experimental with simulated spectra. Meanwhile, the rotational and vibrational temperatures of the diffuse discharge plasma are also discussed under different pulse peak voltages and pulse repetition rates, respectively. In addition, the diffuse air discharge plasma can form an area of about 70×50 mm(2) on the surface of dielectric layer and can be scaled up to the required size.

  18. Influence of air diffusion on the OH radicals and atomic O distribution in an atmospheric Ar (bio)plasma jet

    NASA Astrophysics Data System (ADS)

    Nikiforov, A.; Li, L.; Britun, N.; Snyders, R.; Vanraes, P.; Leys, C.

    2014-02-01

    Treatment of samples with plasmas in biomedical applications often occurs in ambient air. Admixing air into the discharge region may severely affect the formation and destruction of the generated oxidative species. Little is known about the effects of air diffusion on the spatial distribution of OH radicals and O atoms in the afterglow of atmospheric-pressure plasma jets. In our work, these effects are investigated by performing and comparing measurements in ambient air with measurements in a controlled argon atmosphere without the admixture of air, for an argon plasma jet. The spatial distribution of OH is detected by means of laser-induced fluorescence diagnostics (LIF), whereas two-photon laser-induced fluorescence (TALIF) is used for the detection of atomic O. The spatially resolved OH LIF and O TALIF show that, due to the air admixture effects, the reactive species are only concentrated in the vicinity of the central streamline of the afterglow of the jet, with a characteristic discharge diameter of ˜1.5 mm. It is shown that air diffusion has a key role in the recombination loss mechanisms of OH radicals and atomic O especially in the far afterglow region, starting up to ˜4 mm from the nozzle outlet at a low water/oxygen concentration. Furthermore, air diffusion enhances OH and O production in the core of the plasma. The higher density of active species in the discharge in ambient air is likely due to a higher electron density and a more effective electron impact dissociation of H2O and O2 caused by the increasing electrical field, when the discharge is operated in ambient air.

  19. Laser-produced plasma measurement of thermal diffusivity of molten metals

    SciTech Connect

    Kim, Yong W.; Park, C.S.

    1995-12-01

    We have shown that a laser-produced plasma plume which is representative in composition of the condensed phase target can be reproducibly generated if the movement of the surface due to evaporation is kept in pace with the thermal diffusion front propagating into the bulk. The resulting mass loss is then strongly controlled by the thermal diffusivity of the target matter, and this relationship has been exploited to measure the thermal diffusivity of metallic alloys. We have developed a novel RF levitator-heater as a contamination-free molten metal source to be used as a target for LPP plume generation. In order to determine the mass loss due to LPP excitation, a new high sensitivity transducer has been constructed for measurement of the resulting impulse imparted on the specimen. The impulse transducer is built onto the specimen holder within the levitation-assisted molten metal source. The LPP method has been fully excercised for measurement of the thermal diffusivity of a molten specimen relative to the value for its room temperature solid. The results for SS304 and SS316 are presented together with a critique of the results. A numerical modeling of specimen heating in the molten metal source and the physical basis of the new hod are also presented.

  20. Plasma-produced erbia coatings for waste reduction in plutonium casting operations

    SciTech Connect

    Wood, B.P.; Soderquist, D.; Gurevitch, A.; Steele, J.; Hampel, F.; Walter, K.C.; Perry, A.J.; Treglio, J.

    1997-12-31

    Disposal of molds used in plutonium casting operations creates a significant waste stream, since such molds are typically only used once or twice, due to the highly corrosive nature of molten plutonium. Erbia (erbium oxide) is inert to molten plutonium, but being a brittle ceramic material, is difficult to make adhere to mold surfaces under severe conditions of thermal expansion mismatch. The authors report on efforts to utilize an ion implantation process to improve the adhesion of erbia coatings deposited from a cathodic arc derived erbium plasma. Coatings were created using both dc and pulsed cathodic arc sources in a low pressure oxygen background. Ion implantation was achieved by pulse biasing the target to several 10`s of kilovolts during some steps in the process. This high energy ion bombardment was found to produce superior coating adhesion, and treated samples successfully resisted attack from molten plutonium in a casting test. The effect of variations in ion implantation parameters, coating parameters, and coating stoichiometry is discussed.