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Sample records for plasma jet array

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

    NASA Astrophysics Data System (ADS)

    Robert, Eric

    2015-09-01

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

  2. Uniformity optimization and dynamic studies of plasma jet array interaction in argon

    NASA Astrophysics Data System (ADS)

    Wang, Ruixue; Sun, Hao; Zhu, Weidong; Zhang, Cheng; Zhang, Shuai; Shao, Tao

    2017-09-01

    In this paper, the uniformity of a microsecond pulse driven argon plasma jet array is studied by optimizing experimental parameters, such as the ground electrode position d, gas flow rate, and pulse frequency. The results show that when d is less than 10 mm, there are always two plasma jets that cannot be ignited; while all jets are ignited with equal length at d = 12.5 mm. The plasma jet transition from laminar to turbulent at 6 l/min, presenting a "bead-like" structure. The jet length increases with the pulse repetition frequency and reaches a plateau at around 1.5 kHz. The ICCD images show that the plasma jets emerged preferably from the two quartz tubings located at the two ends of the linear array. The spatial-temporal resolved spectra show that the Ar emission (763.5 nm) and N2 emission (337.1 nm) at the end of the array (e.g., Jet #1) appeared earlier than that of the jet in the middle (e.g., Jet #2). On the contrary, the emission intensities of Ar in Jet #2 are higher than in Jet #1. This is due to the higher electric field and air diffusion at the plasma array boundary.

  3. The effect of applied electric field on pulsed radio frequency and pulsed direct current plasma jet array

    SciTech Connect

    Hu, J. T.; Liu, X. Y.; Liu, J. H.; Xiong, Z. L.; Liu, D. W.; Lu, X. P.; Iza, F.; Kong, M. G.

    2012-06-15

    Here we compare the plasma plume propagation characteristics of a 3-channel pulsed RF plasma jet array and those of the same device operated by a pulsed dc source. For the pulsed-RF jet array, numerous long life time ions and metastables accumulated in the plasma channel make the plasma plume respond quickly to applied electric field. Its structure similar as 'plasma bullet' is an anode glow indeed. For the pulsed dc plasma jet array, the strong electric field in the vicinity of the tube is the reason for the growing plasma bullet in the launching period. The repulsive forces between the growing plasma bullets result in the divergence of the pulsed dc plasma jet array. Finally, the comparison of 309 nm and 777 nm emissions between these two jet arrays suggests the high chemical activity of pulsed RF plasma jet array.

  4. Plasma jet array treatment to improve the hydrophobicity of contaminated HTV silicone rubber

    NASA Astrophysics Data System (ADS)

    Zhang, Ruobing; Han, Qianting; Xia, Yan; Li, Shuang

    2017-10-01

    An atmospheric-pressure plasma jet array specially designed for HTV silicone rubber treatment is reported in this paper. Stable plasma containing highly energetic active particles was uniformly generated in the plasma jet array. The discharge pattern was affected by the applied voltage. The divergence phenomenon was observed at low gas flow rate and abated when the flow rate increased. Temperature of the plasma plume is close to room temperature which makes it feasible for temperature-sensitive material treatment. Hydrophobicity of contaminated HTV silicone rubber was significantly improved after quick exposure of the plasma jet array, and the effective treatment area reached 120 mm × 50 mm (length × width). Reactive particles in the plasma accelerate accumulation of the hydrophobic molecules, namely low molecular weight silicone chains, on the contaminated surface, which result in a hydrophobicity improvement of the HTV silicone rubber.

  5. Experiments With Radiatively Cooled Supersonic Plasma Jets Generated in Conical Wire Array Z-Pinches

    NASA Astrophysics Data System (ADS)

    Lebedev, S. V.; Ampleford, D. J.; Bland, S. N.; Chittenden, J. P.; Ciardi, A.; Naz, N.; Haines, M. G.; Frank, A.; Blackman, E.; Gardiner, T.

    2002-12-01

    We present results of astrophysically relevant experiments where highly supersonic plasma jets are generated via conically convergent plasma flows in a conical wire array Z-pinch. Stagnation of plasma flow on the axis of symmetry forms a standing conical shock effectively collimating the flow in the axial direction. This scenario is essentially similar to that discussed by Canto and collaborators [1] as a purely hydrodynamic mechanism for jet formation in astrophysical systems. Experiments using different materials (Al, Fe and W) show that a hypersonic (M ~ 20), well-collimated jet is generated when the radiative cooling rate of the plasma is significant.

  6. Influence of gas flow and applied voltage on interaction of jets in a cross-field helium plasma jet array

    NASA Astrophysics Data System (ADS)

    Wan, Meng; Liu, Feng; Fang, Zhi; Zhang, Bo; Wan, Hui

    2017-09-01

    Atmospheric Pressure Plasma Jet arrays can greatly enhance the treatment area to fulfill the need for large-scale surface processing, while the spatial uniformity of the plasma jet array is closely related to the interactions of the adjacent jets. In this paper, a three-tube one-dimensional (1D) He plasma jet array with a cross-field needle-ring electrode structure is used to investigate the influences of the gas flow rate and applied voltage on the interactions of the adjacent jets through electrical, optical, and fluid measurements. The repulsion of the adjacent plume channels is observed using an intensified charge-coupled device (ICCD) and the influence of the gas flow rate and applied voltage on the electrostatic repulsion force, Coulomb force, is discussed. It is found that electrical coupling, mainly electrostatic repulsion force, exists among the jets in the array, which causes both the divergence of the lateral plumes and the nonlinear changes of the discharge power and the transport charge. The deflection angle of the lateral plumes with respect to the central plume in the optical images increases with the increase of applied voltage and decreases with the increase of gas flow rate. The deflection angle of the lateral plumes in the optical images is obviously larger than that of the lateral gas streams in the Schlieren images under the same experimental conditions, and the unconformity of the deflection angles is mainly attributed to the electrostatic repulsion force in adjacent plasma plume channels. The experimental results can help understand the interaction mechanisms of jets in the array and design controllable and scalable plasma jet arrays.

  7. Effect of O2 additive on spatial uniformity of atmospheric-pressure helium plasma jet array driven by microsecond-duration pulses

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Shao, Tao; Zhou, Yixiao; Fang, Zhi; Yan, Ping; Yang, Wenjin

    2014-07-01

    Plasma jet array is a promising device for producing low-temperature plasma at atmospheric pressure. In our letter, the effect of O2 additive on spatial uniformity of one-dimensional helium plasma jet array is described. The length of the plasma jet in the middle of the array before the injection of O2 additive is less than that on the edges of the array. However, when a small amount of O2 additive is injected into the plasma jet array, the length increases and becomes approximately the same as the length of the plasma jets on the edges of the array. The improvement of spatial uniformity of the plasma jet array is due to the enhancement of the Penning ionization in the plasma jets caused by O2 additive. Too much quantity of O2 additive, however, may lead to discharge quenching in the plasma jet array.

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

    SciTech Connect

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

    2015-12-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  10. Radiatively cooled supersonic plasma jets generated in wire array Z-pinches

    NASA Astrophysics Data System (ADS)

    Bland, Simon; Lebedev, Sergey; Chittenden, Jerry; Beg, F. N.; Ciardi, A.; Haines, M. G.

    2000-10-01

    We will present experiments on the generation of a highly supersonic plasma jet by a convergent plasma flow, produced by electrodynamic acceleration of plasma in a conical array of fine metallic wires (a modification of the wire array Z-pinch [1]). Stagnation of the plasma flow on the axis of symmetry forms a standing conical shock, which effectively collimates the flow in the axial direction. This scenario is essentially similar to that discussed by Cantó et al. [2] as a possible, purely hydrodynamic mechanism of jet formation in young stellar objects. Experiments using different materials (Al, Fe and W) show that a highly supersonic (M 20) and a well-collimated jet is generated when the radiative cooling rate of the plasma is significant. The interaction of this jet with a plasma target could be used for scaled [3] laboratory astrophysical experiments on hydrodynamic instabilities in decelerated plasma flow. [1] M.K. Matzen, Phys. Plasmas v.4, 1519 (1997) [2] J. Cantó, et. al. Astron. Astrophys. v.192, 287 (1994). [3] D. Ryutov et al., ApJ, v.518, 821 (1999)

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

    SciTech Connect

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

    2013-03-15

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

  12. Diagnostics of an AC driven atmospheric pressure non-thermal plasma jet and its use for radially directed jet array

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Wang, R.

    2017-08-01

    An alternating current atmospheric pressure plasma jet is generated with noble gas or noble gas/oxygen admixture as working gas. A "core plasma filament" is observed at the center of the dielectric tube and extends to the plasma jet at higher peak-to-peak voltages. This type of plasma jet is believed to be of the same nature with the reported plasma bullet driven by pulsed DC power sources. Double current probes are used to assess the speed of the plasma bullet and show that the speed is around 104-105 m/s. The time dependence of the downstream bullet speed is attributed to the gas heating and in turn the increase of the reduced electric field E/N. Optical emission spectra show the dependence of helium and oxygen emission intensities on the concentration of oxygen additive in the carrier gas, with peak values found at 0.5% O2. Multiple radial jets are realized on dielectric tubes of different sizes. As a case study, one of these multi-jet devices is used to treat B. aureus on the inner surface of a plastic beaker and is shown to be more effective than a single jet.

  13. Interactions Between Small Arrays of Atmospheric Pressure Micro-Plasma Jets: Gas Dynamic, Radiation and Electrostatic Interactions

    NASA Astrophysics Data System (ADS)

    Babaeva, Natalia

    2013-09-01

    Atmospheric pressure plasma jets are widely used devices for biomedical applications. A typical plasma jet consists of a tube through which noble gas or its mixture with a molecular gas flows. The noble gas creates a channel into the ambient air which is eventually dispersed by interdiffusion with the air. Plasma plumes are formed by the propagation of ionization waves (IWs) through the tubes and then through the noble gas phase channel. The IW typically propagates until the mole fraction of the ambient air in the channel increases above a critical values which requires a larger E/N to propagate the IW. By grouping several jets together to form an array of jets, one can in principle increase the area treated by the plume. If the jets are sufficiently far apart, the IWs and resulting plasma plumes are independent. As the spacing between the jets decreases, the plasma jets begin to mutually interact. In this talk, we discuss results from a computational investigation of small arrays of He/O2 micro-plasma jets propagating into ambient air. The model used in this work, nonPDPSIM, is a plasma hydrodynamics model in which continuity, momentum and energy equations are solved for charged and neutral species with solution of Poisson's equation for the electric potential. Navier-Stokes equations are solved for the gas dynamics and radiation transport is addressed using a propagator method. We found that as the spacing between the jets decreases, the He channels from the individual jets tend to merge. The IWs from each channel also merge into regions having the highest He mole fraction and so lowest E/N to sustain the IW. The proximity of the IWs enable other forms of interaction. If the IWs are of the same polarity, electrostatic forces can warp the paths of the IWs. If in sufficient proximity, the photoionization from one IW can influence its neighbors. The synchronization of the voltage pulses of adjacent IWs can also influence its neighbors. With synchronized pulses

  14. Atmospheric-pressure plasma-jet from micronozzle array and its biological effects on living cells for cancer therapy

    SciTech Connect

    Kim, Kangil; Kim, Geunyoung; Yang, Sang Sik; Choi, Jae Duk; Hong, Yong Cheol; Noh, Eun Joo; Lee, Jong-Soo

    2011-02-14

    We propose a plasma-jet device with a micrometer-sized nozzle array for use in a cancer therapy. Also, we show the biological effects of atmospheric-pressure plasma on living cells. Nitrogen-plasma activated a surrogate DNA damage signal transduction pathway, called the ataxia telangiectasia mutated (ATM)-checkpoint kinase 2 pathway, suggesting that the nitrogen-plasma generates DNA double-strand breaks. Phosphorylation of H2AX and p53 was detected in the plasma-treated cells, leading to apoptotic cell death. Thus, an effect for the nitrogen plasma in the control of apoptotic cell death provides insight into the how biological effects of the nitrogen-plasma can be applied to the control of cell survival, a finding with potential therapeutic implications.

  15. Atmospheric-pressure plasma-jet from micronozzle array and its biological effects on living cells for cancer therapy

    NASA Astrophysics Data System (ADS)

    Kim, Kangil; Choi, Jae Duk; Hong, Yong Cheol; Kim, Geunyoung; Noh, Eun Joo; Lee, Jong-Soo; Yang, Sang Sik

    2011-02-01

    We propose a plasma-jet device with a micrometer-sized nozzle array for use in a cancer therapy. Also, we show the biological effects of atmospheric-pressure plasma on living cells. Nitrogen-plasma activated a surrogate DNA damage signal transduction pathway, called the ataxia telangiectasia mutated (ATM)-checkpoint kinase 2 pathway, suggesting that the nitrogen-plasma generates DNA double-strand breaks. Phosphorylation of H2AX and p53 was detected in the plasma-treated cells, leading to apoptotic cell death. Thus, an effect for the nitrogen plasma in the control of apoptotic cell death provides insight into the how biological effects of the nitrogen-plasma can be applied to the control of cell survival, a finding with potential therapeutic implications.

  16. Spatially extended atmospheric plasma arrays

    NASA Astrophysics Data System (ADS)

    Cao, Z.; Nie, Q.; Bayliss, D. L.; Walsh, J. L.; Ren, C. S.; Wang, D. Z.; Kong, M. G.

    2010-04-01

    This paper reports a systematic study of spatially extended atmospheric plasma (SEAP) arrays employing many parallel plasma jets packed densely and arranged in an honeycomb configuration. The work is motivated by the challenge of using inherently small atmospheric plasmas to address many large-scale processing applications including plasma medicine. The first part of the study considers a capillary-ring electrode configuration as the elemental jet with which to construct a 2D SEAP array. It is shown that its plasma dynamics is characterized by strong interaction between two plasmas initially generated near the two electrodes. Its plume length increases considerably when the plasma evolves into a high-current continuous mode from the usual bullet mode. Its electron density is estimated to be at the order of 3.7 × 1012 cm-3. The second part of the study considers 2D SEAP arrays constructed from parallelization of identical capillary-ring plasma jets with very high jet density of 0.47-0.6. Strong jet-jet interactions of a 7-jet 2D array are found to depend on the excitation frequency, and are effectively mitigated with the jet-array structure that acts as an effective ballast. The impact range of the reaction chemistry of the array exceeds considerably the cross-sectional dimension of the array itself, and the physical reach of reactive species generated by any single jet exceeds significantly the jet-jet distance. As a result, the jet array can treat a large sample surface without relative sample-array movement. A 37-channel SEAP array is used to indicate the scalability with an impact range of up to 48.6 mm in diameter, a step change in capability from previously reported SEAP arrays. 2D SEAP arrays represent one of few current options as large-scale low-temperature atmospheric plasma technologies with distinct capability of directed delivery of reactive species and effective control of the jet-jet and jet-sample interactions.

  17. Atmospheric plasma jet array in parallel electric and gas flow fields for three-dimensional surface treatment

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

    This letter reports on electrical and optical characteristics of a ten-channel atmospheric pressure glow discharge jet array in parallel electric and gas flow fields. Challenged with complex three-dimensional substrates including surgical tissue forceps and sloped plastic plate of up to 15°, the jet array is shown to achieve excellent jet-to-jet uniformity both in time and in space. Its spatial uniformity is four times better than a comparable single jet when both are used to treat a 15° sloped substrate. These benefits are likely from an effective self-adjustment mechanism among individual jets facilitated by individualized ballast and spatial redistribution of surface charges.

  18. Plasma confinement at JET

    NASA Astrophysics Data System (ADS)

    Nunes, I.; JET Contributors

    2016-01-01

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

  19. Plasma jets merging simulation

    NASA Astrophysics Data System (ADS)

    Galkin, S. A.; Bogatu, I. N.; Kim, J. S.; Witherspoon, F. D.; Phillips, M. W.; Hughes, T. P.; Welch, D. R.; Golovkin, I.; Macfarlane, J.

    2007-11-01

    The progress on numerical 3D simulations of high density high Mach number plasma jets merging is presented. The modeling was conducted with the particle-in-cell LSP code [1]. A few hypersonic plasma jets (Mach number between 5 and 50) with high density (within the range of 10^15-10^17 cm-3) were injected for merging in a low density low temperature neutral background gas ( 10^13 cm-3). The dynamics of the merging was studied. Onset of a strong instability, which was observed in the modeling of two, three and five plasma merging jets [2], can essentially affect the front formation and finally can lead to a high turbulent flow. The nature of the instability is discussed. The progress on HyperV plasma accelerator experiment simulation and comparison with a recent experimental data is also reported. [1] T. P. Hughes, S. S. Yu, and R. E. Clark, Phys. Rev. ST Accel. Beams 2, 110401, 1999. [2] S. A. Galkin, I. N. Bogatu, J. S. Kim, to be published in PPPS/ICOP 2007 Conference Proceedings. Work is supported by the US DOE SBIR grant and by US DOE Office of Fusion Energy Sciences.

  20. Plasma jet takes off.

    PubMed Central

    Frazer, L

    1999-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    technological solution in the early to late 1990s of confining atmospheric plasmas in a small volume of plasma generation (i.e. with a small volume-to-surface ratio) and then extending it towards a downstream sample [7]-[9]. These are among the first low-temperature atmospheric plasmas aimed particularly at the exploitation of their ability to invoke the active and rich reactive chemistry close to ambient temperature. The main applications of these early devices are precision surface modification of low-temperature dielectric materials, for example thin film deposition and etching [7]-[9]. Variations of the early plasma jets include atmospheric plasma sheet jets [10] for the treatment of largely planar objects (e.g. polymeric sheets) as well as large arrays of many plasma jets for the treatment of complex-structured objects (e.g. surgical tools and open human wounds) [11]. As a material processing technology, the sub-100oC atmospheric-pressure plasma jet has benefited over the years from many innovations. Whilst a detailed account and analysis of these is clearly outside the scope of this Editorial, it is worth stating that there are different avenues with which to maintain a moderate electron density at the plasma core so as to keep the gas temperature at the sample point below a ceiling level. Most of the early studies employed excitation at radio frequencies above 10 MHz, at which electrons are largely confined in the plasma generation region, and this limits the current flow to and gas heating in the plume region of the plasma jet. Other techniques of current limitation have since been shown to be effective, including the use of dielectric barriers across a very large frequency range of 1 kHz--50 MHz, sub-microsecond pulses sustained at kHz frequencies, pulse-modulated radio frequencies and dual-frequency excitation [12]-[15]. These and other techniques have considerably advanced the atmospheric-pressure plasma jet technology. The period of some 15 years since the above

  2. Plasma jet ignition device

    DOEpatents

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

    1985-01-15

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

  3. Patterned Surface Functionalization of Dot-Arrayed CNTs for Biochip Sensor Using Scannable Ultrafine Atmospheric Pressure Plasma Jet

    NASA Astrophysics Data System (ADS)

    Okada, Mitsuru; Abuzairi, Tomy; Bhattacharjee, Sudeep; Poespawati, Nji R.; Purnamaningsih, Rento W.; Nagatsu, Masaaki

    2015-09-01

    The present results show that the feasibility of using a dot-arrayed CNT as a biochip sensor was demonstrated by successfully fabricating CNTs in an array form and performing patterned surface functionalization of amino and carboxyl groups onto CNT. The vertically aligned CNT was fabricated in an array form using a combined thermal-plasma CVD for realizing the development of biochip sensors. Patterned surface functionalization was developed by ultrafine APPJ in two stages: (1) pretreatment by He gas with -500V dc bias and (2) posttreatment without bias by a He/NH3 gas mixture for amino group or by a He/O2 gas mixture for carboxyl group functionalization. The analysis results of chemical derivatization indicate that amino and carboxyl groups successfully functionalized the CNT dot array without interfering with each other. The optimum period of ultrafine APPJ treatments was achieved by balancing the following 3 aspects: (1) effective area of modification, (2) amount of surface functionalization, and (3) damage of the CNT. Finally, the patterned surface functionalization of amino and carboxyl groups was successfully conducted in the arbitrary pattern by using ultrafine APPJ automatically scanned by computer-controlled precision stage.

  4. Plasma Jet Modeling for PLX

    NASA Astrophysics Data System (ADS)

    Mason, Caroline F.; Mason, Rodney J.; Faehl, R. J.; Kirkpatrick, R. C.

    2011-10-01

    The implicit simulation code ePLAS has been applied to plasma jets generated with mini-rail guns for plasma production and compression aimed at use with PLX. The rails are typically planar, 2.5 cm apart and arranged to transport an initial 1 cm or wider vertical plasma fill some 10 cm into a void. The driving magnetic field is 3.2 T. The plasma singly ionized argon at 1017 cm-3. We use ePLAS in both its traditional implicit/hybrid form where it is restricted by an electron Courant time step, and in a new super-hybrid form that extracts the main electron moments from the E&B-field solutions. This provides numerical stability at ion Courant limits, for at least a 10 times larger time step, thus probing microsecond jet dynamics with computational economy. We examine possible field penetration at the cathode and anode gun electrodes. Cathode erosion and EMHD B - Field penetration are possible at lower jet densities. We examine jet transport beyond the gun, modeling possible ionization with either analytic or tabular EOSs. We study the merger of jets with ions represented as either fluids or particles. Work supported by the USDOE under SBIR GRANT DE-SC0004207.

  5. Propagation Of Dense Plasma Jets

    NASA Astrophysics Data System (ADS)

    Turchi, Peter J.; Davis, John F.

    1988-05-01

    A variety of schemes have been proposed over the last two decades for delivering lethal amounts of energy and/or momentum to targets such as missiles and high speed aircraft. Techniques have ranged from high energy lasers and high voltage charged-particle accelerators to less exotic but still challenging devices such as electromagnetic railguns. One class of technology involves the use of high speed plasmas. The primary attraction of such technology is the possibility of utilizing relatively compact accelerators and electrical power systems that could allow highly mobile and agile operation from rocket or aircraft platforms, or in special ordnance. Three years ago, R & D Associates examined the possibility of plasma propagation for military applications and concluded that the only viable approach consisted of long dense plasma jets, contained in radial equilibrium by the atmosphere, while propagating at speeds of about 10 km/s. Without atmospheric confinement the plasma density would diminish too rapidly for adequate range and lethality. Propagation of atmospherically-confined jets at speeds much greater than 10 km/s required significant increases in power levels and/or operating altitudes to achieve useful ranges. The present research effort has been developing the experimental conditions necessary to achieve reasonable comparison with theoretical predictions for plasma jet propagation in the atmosphere. Time-resolved measurements have been made of high speed argon plasma jets penetrating a helium background (simulating xenon jets propagating into air). Basic radial confinement of the jet has been observed by photography and spectroscopy and structures in the flow field resemble those predicted by numerical calculations. Results from our successful initial experiments have been used to design improved diagnostic procedures and arcjet source characteristics for further experiments. In experiments with a modified arcjet source, radial confinement of the jet is again

  6. Off-axis chemical crosstalk in an atmospheric pressure microplasma jet array

    NASA Astrophysics Data System (ADS)

    Sun, P. P.; Chen, H. L.; Park, S.-J.; Eden, J. G.; Liu, D. X.; Kong, M. G.

    2015-10-01

    Developing arrays of parallel microplasma jets is an attractive route to scaling the area available for the treatment of surfaces with low temperature plasma. Increasing the packing density of the arrays may lead to electrical and gas kinetic jet-jet interactions, but previous work has focused almost exclusively on electrostatic coupling between the jets. Chemical interactions (‘crosstalk’) have received considerably less attention. We report here the results of an investigation of chemical crosstalk in 4  ×  4 arrays of microplasma jets, produced in flowing helium at atmospheric pressure. Oxidation damage to an Escherichia coli lawn serves as a diagnostic of the spatial distribution of molecular radicals and other reactive plasma species, produced at the plasma jet/ambient background interface or between the jets, and incident on the surface. Spatial maps of bacterial inactivation by the microplasma jet array for 20 s show the destruction of E. coli at distances as large as 2.7 jet diameter from the nearest plasma perimeter, compared to typically less than 0.5 jet diameter in the single jet case. Extending to 30 s of plasma exposure leads to destruction of the entire bacterial sample. This ‘action at a distance’ effect, the production of long-lived species such as O, O2(a1Δg) and O3 that are responsible for bacterial deactivation, peaks along a line bisecting columns and rows of plasma jets. The data illustrate the synergistic effect of adjacent jets on off-axis formation of reactive species, and show that the chemical and biological impact of an array cannot be inferred from the plasma chemistry of a single jet.

  7. Atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S.

    1999-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  9. Observation of alpha particle loss from JET plasmas during ion cyclotron resonance frequency heating using a thin foil Faraday cup detector array.

    PubMed

    Darrow, D S; Cecil, F E; Kiptily, V; Fullard, K; Horton, A; Murari, A

    2010-10-01

    The loss of MeV alpha particles from JET plasmas has been measured with a set of thin foil Faraday cup detectors during third harmonic heating of helium neutral beam ions. Tail temperatures of ∼ 2 MeV have been observed, with radial scrape off lengths of a few centimeters. Operational experience from this system indicates that such detectors are potentially feasible for future large tokamaks, but careful attention to screening rf and MHD induced noise is essential.

  10. Chaos in atmospheric-pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Walsh, J. L.; Iza, F.; Janson, N. B.; Kong, M. G.

    2012-06-01

    We report detailed characterization of a low-temperature atmospheric-pressure plasma jet that exhibits regimes of periodic, quasi-periodic and chaotic behaviors. Power spectra, phase portraits, stroboscopic section and bifurcation diagram of the discharge current combine to comprehensively demonstrate the existence of chaos, and this evidence is strengthened with a nonlinear dynamics analysis using two control parameters that maps out periodic, period-multiplication, and chaotic regimes over a wide range of the input voltage and gas flow rate. In addition, optical emission signatures of excited plasma species are used as the second and independent observable to demonstrate the presence of chaos and period-doubling in both the concentrations and composition of plasma species, suggesting a similar array of periodic, quasi-periodic and chaotic regimes in plasma chemistry. The presence of quasi-periodic and chaotic regimes in structurally unbounded low-temperature atmospheric plasmas not only is important as a fundamental scientific topic but also has interesting implications for their numerous applications. Chaos may be undesirable for industrial applications where cycle-to-cycle reproducibility is important, yet for treatment of cell-containing materials including living tissues it may offer a novel route to combat some of the major challenges in medicine such as drug resistance. Chaos in low-temperature atmospheric plasmas and its effective control are likely to open up new vistas for medical technologies.

  11. Impingement Heat Transfer of Reciprocating Jet Array

    NASA Astrophysics Data System (ADS)

    Su, Lo May; Chang, Shyy Woei; Chiou, Shyr Fuu

    This paper describes an experimental study of impingement heat transfer of reciprocating jet-array with piston cooling application for marine heavy-duty diesel engine. A selection of heat transfer measurements illustrates the manner by which the individual and interactive influences of reciprocating force and buoyancy on heat transfer for the impinging jet-array. It is demonstrated that the reciprocating force coupled with buoyancy interaction causes considerable heat transfer modifications from the static results. The isolated reciprocating force effect could initially reduce heat transfer to a level about 0.45 of static level with weak reciprocation but recovers when the reciprocating force increases. Heat transfer improvement and impediment could be aided by the location-dependent buoyancy effect in addition to the reciprocating force effect. An empirical heat transfer correlation, which is physically consistent, has been developed to permit the evaluation of the individual and synergistic effects of reciprocating force and buoyancy interaction on local heat transfer of the impinging jet-array.

  12. Atmospheric-Pressure Plasma Jet Induces Apoptosis Involving Mitochondria via Generation of Free Radicals

    PubMed Central

    Kim, Geunyoung; Moon, Eunpyo; Yang, Sang Sik; Lee, Jong-Soo

    2011-01-01

    The plasma jet has been proposed as a novel therapeutic method for anticancer treatment. However, its biological effects and mechanism of action remain elusive. Here, we investigated its cell death effects and underlying molecular mechanisms, using air and N2 plasma jets from a micro nozzle array. Treatment with air or N2 plasma jets caused apoptotic death in human cervical cancer HeLa cells, simultaneously with depolarization of mitochondrial membrane potential. In addition, the plasma jets were able to generate reactive oxygen species (ROS), which function as surrogate apoptotic signals by targeting the mitochondrial membrane potential. Antioxidants or caspase inhibitors ameliorated the apoptotic cell death induced by the air and N2 plasma jets, suggesting that the plasma jet may generate ROS as a proapoptotic cue, thus initiating mitochondria-mediated apoptosis. Taken together, our data suggest the potential employment of plasma jets as a novel therapy for cancer. PMID:22140530

  13. Atmospheric-pressure plasma jet induces apoptosis involving mitochondria via generation of free radicals.

    PubMed

    Ahn, Hak Jun; Kim, Kang Il; Kim, Geunyoung; Moon, Eunpyo; Yang, Sang Sik; Lee, Jong-Soo

    2011-01-01

    The plasma jet has been proposed as a novel therapeutic method for anticancer treatment. However, its biological effects and mechanism of action remain elusive. Here, we investigated its cell death effects and underlying molecular mechanisms, using air and N₂ plasma jets from a micro nozzle array. Treatment with air or N₂ plasma jets caused apoptotic death in human cervical cancer HeLa cells, simultaneously with depolarization of mitochondrial membrane potential. In addition, the plasma jets were able to generate reactive oxygen species (ROS), which function as surrogate apoptotic signals by targeting the mitochondrial membrane potential. Antioxidants or caspase inhibitors ameliorated the apoptotic cell death induced by the air and N₂ plasma jets, suggesting that the plasma jet may generate ROS as a proapoptotic cue, thus initiating mitochondria-mediated apoptosis. Taken together, our data suggest the potential employment of plasma jets as a novel therapy for cancer.

  14. Atmospheric pressure plasma jet applications

    SciTech Connect

    Park, J.; Herrmann, H.W.; Henins, I.; Selwyn, G.S.

    1998-12-31

    The atmospheric pressure plasma jet (APPJ) is a non-thermal, high pressure plasma discharge that produces a high velocity effluent stream of highly reactive chemical species. The discharge operates on a feedstock gas (e.g., He/O2/H2O) which flows between two concentric cylindrical electrodes: an outer grounded electrode and an inner electrode powered at 13.56 MHz RF. While passing through the plasma, the feedgas becomes excited, ionized or dissociated by electron impact. The fast-flowing effluent consists of ions and electrons, which are rapidly lost by recombination, highly reactive radicals (e.g., O, OH), and metastable species (e.g., O2). The metastable O2, which is reactive to hydrocarbon and other organic species, has been observed through optical emission spectroscopy to decrease by a factor of 2 from the APPJ nozzle exit to a distance of 10 cm. Unreacted metastable O2, and that which does not impinge on a surface, will then decay back to ordinary ground state O2, resulting in a completely dry, environmentally-benign form of surface cleaning. Applications such as removal of photoresist, oxide films and organic residues from wafers for the electronics industry, decontamination of civilian and military areas and personnel exposed to chemical or biological warfare agents, and paint (e.g., graffiti) removal are being considered.

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

    SciTech Connect

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

    2015-02-02

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

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

    NASA Astrophysics Data System (ADS)

    Topala, I.; Nagatsu, M.

    2015-02-01

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

  17. Jet flow and premixed jet flame control by plasma swirler

    NASA Astrophysics Data System (ADS)

    Li, Gang; Jiang, Xi; Zhao, Yujun; Liu, Cunxi; Chen, Qi; Xu, Gang; Liu, Fuqiang

    2017-04-01

    A swirler based on dielectric barrier discharge plasma actuators is designed and its effectiveness in both jet flow and premixed jet flame control is demonstrated. In contrast to traditional spanwise-oriented actuators, plasma actuators are placed along the axial direction of the injector to induce a circumferential velocity to the main flow and create a swirl flow without any insertion or moving part. In the DBD plasma swirl injector, the discharge does not ignite the mixture nor does it induce flashback. Flame visualization is obtained by cameras while velocity profiles are obtained by Laser Doppler Anemometry measurements. The results obtained indicate the effectiveness of the new design.

  18. Mechanisms of Plasma Acceleration in Coronal Jets

    NASA Astrophysics Data System (ADS)

    Soto, N.; Reeves, K.; Savcheva, A. S.

    2016-12-01

    Jets are small explosions that occur frequently in the Sun possibly driven by the local reconfiguration of the magnetic field, or reconnection. There are two types of coronal jets: standard jets and blowout jets. The purpose of this project is to determine which mechanisms accelerate plasma in two different jets, one that occurred in January 17, 2015 at the disk of the sun and another in October 24, 2015 at the limb. Two possible acceleration mechanisms are chromospheric evaporation and magnetic acceleration. Using SDO/AIA, Hinode/XRT and IRIS data, we create height-time plots, and calculate the velocities of each wavelength for both jets. We calculate the potential magnetic field of the jet and the general region around it to gain a more detailed understanding of its structure, and determine if the jet is likely to be either a standard or blowout jet. Finally, we calculate the magnetic field strength for different heights along the jet spire, and use differential emission measures to calculate the plasma density. Once we have these two values, we calculate the Alfven speed. When analyzing our results we are looking for certain patterns in our velocities. If the plasma in a jet is accelerated by chromospheric evaporation, we expect the velocities to increase as function of temperature, which is what we observed in the October 24th jet. The magnetic models for this jet also show the Eiffel Tower shaped structure characteristic of standard jets, which tend to have plasma accelerated by this mechanism. On the other hand, if the acceleration mechanism were magnetic acceleration, we would expect the velocities to be similar regardless of temperature. For the January 17th jet, we saw that along the spire, the velocities where approximately 200 km/s in all wavelengths, but the velocities of hot plasma detected at the base were closer to the Alfven speed, which was estimated to be about 2,000 km/s. These observations suggest that the plasma in the January 17th jet is

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  20. Hypersonic Induced Interactions of Plasma and Non-Plasma Jets

    DTIC Science & Technology

    2006-06-12

    optimised . A preliminary assessment of the effects of plasma actuators on jet and jet in crossflow was conducted. NOMENCLATURE C Chapman-Rubesin...highly adaptable so as to allow for efficient changeover between the use of different geometries . The model was a zero incidence flat plate with a...Final Report: FA8655-07-1-3032 / Kontis, K Figure 7: Schematic of flat plate geometry Table 1 Pressure tappings. The non-plasma air jet was

  1. Coronal Jet Plasma Properties and Acceleration Mechanisms

    NASA Astrophysics Data System (ADS)

    Farid, Samaiyah; Reeves, Kathy; Savcheva, Antonia; Soto, Natalia

    2017-08-01

    Coronal jets are transient eruptions of plasma typically characterized by aprominent long spire and a bright base, and sometimes accompanied by a small filament. Jets are thought to be produced by magnetic reconnection when small-scale bipolar magnetic fields emerge into an overlying coronal field or move into a locally unipolar region. Coronal jets are commonly divided into two categories: standard jets and blowout jets, and are found in both quiet and active regions. The plasma properties of jets vary across type and location, therefore understanding the underlying acceleration mechanisms are difficult to pin down. In this work, we examine both blow-out and standard jets using high resolution multi-wavelength data. Although reconnection is commonly accepted as the primary acceleration mechanism, we also consider the contribution chromospheric evaporation to jet formation. We use seven coronal channels from SDO/AIA , Hinode/XRT Be-thin and IRIS slit-jaw data. In addition, we separate the Fe-XVIII line from the SDO/94Å channel. We calculate plasma properties including velocity, Alfven speed, and density as a function of wavelength and Differential Emission Measure (DEM). Finally, we explore the magnetic topology of the jets using Coronal Modeling System (CMS) to construct potential and non-linear force free models based on the flux rope insertion method.

  2. Mixing in plasma and low density jets

    NASA Astrophysics Data System (ADS)

    Russ, S.; Strykowski, P. J.; Pfender, E.

    1994-04-01

    This study was undertaken to examine the mechanisms which produce the large entrainment measured near the exit of thermal plasma torches. A research facility was constructed to examine low density jet behavior under similar dimensionless conditions as those produced by thermal plasma spray torches; the Reynolds number based on jet diameter and average properties was 1000, and the ratio of jet to ambient density was 0.07. This very low density jet produced organized vortex structures which were partially responsible for the rapid entrainment of external air. The formation of these organized structures could be disrupted by introducing turbulence, but the rapid entrainment process was not significantly affected. The structure of the jet produced by a commercial plasma torch was examined and compared to the low density research jet. At low gas flow rates the plasma jet also displayed the formation of coherent vortex structures, the passage frequency of which compared favorably with that measured in the low density research jet. At higher gas flow rates the shear layer of the plasma jet rapidly broke down producing relatively small scale turbulence. Visualizations of the hot plasma core were compared against measurements of the torch voltage fluctuations caused by arc instabilities. At low flow rates the arc voltage fluctuations were quite low and the plume was very steady. At higher flow rates the arc voltage fluctuations increased and produced “surging” and “whipping” in the hot potential core. It is believed that this low frequency unsteadiness is partially responsible for the rapid entrainment measured in plasma torches.

  3. Merging of high speed argon plasma jets

    SciTech Connect

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

    2013-01-15

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

  4. Characterization of a small railgun-based plasma jet source

    NASA Astrophysics Data System (ADS)

    Schneider, Maximilian; Adams, Colin; Popescu, Marius; Korsness, Joshua; Sherburne, Michael

    2016-10-01

    Experimental characterization of a small plasma jet source has been undertaken at Virginia Tech's Center for Space Science and Engineering Research (Space@VT). The plasma-armature railgun features a square bore approximately 0.5 × 0.5 cm and a rail length of 10 cm. Fed by an 100 psi- gas manifold and powered by an LC pulse-forming network capable of delivering 100 kA current on timescales of several microseconds, jet velocities in the 10-20 km/s range are predicted. A modular design, the insulators and rails are readily swappable for investigation the interaction of the plasma armature with plasma-facing components fabricated with different materials and geometry. The plasma jet is characterized by a suite of diagnostics including a multichord Mach-Zehnder interferometer, spectrometer, photodiode array, and fast photography. Diagnostics planned for the near future include plasma laser-induced fluorescence and particle energy analyzers. The railgun source described is envisioned as a future platform for basic science experiments on topics ranging from plasma-material interaction to plasma shocks.

  5. Jet Noise Source Localization Using Linear Phased Array

    NASA Technical Reports Server (NTRS)

    Agboola, Ferni A.; Bridges, James

    2004-01-01

    A study was conducted to further clarify the interpretation and application of linear phased array microphone results, for localizing aeroacoustics sources in aircraft exhaust jet. Two model engine nozzles were tested at varying power cycles with the array setup parallel to the jet axis. The array position was varied as well to determine best location for the array. The results showed that it is possible to resolve jet noise sources with bypass and other components separation. The results also showed that a focused near field image provides more realistic noise source localization at low to mid frequencies.

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

    SciTech Connect

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

    2015-04-15

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

  7. Structure and Dynamics of Colliding Plasma Jets

    DOE PAGES

    Li, C.; Ryutov, D.; Hu, S.; ...

    2013-12-01

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

  8. Structure and Dynamics of Colliding Plasma Jets

    SciTech Connect

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

    2013-12-01

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

  9. Laboratory-produced MHD plasma jets

    NASA Astrophysics Data System (ADS)

    Bellan, Paul

    2008-04-01

    Because space plasmas are neither confined by vacuum chamber walls nor have magnetic fields produced by physical coils, space plasmas have shapes that are much less determinate than lab plasmas. An experimental program underway at Caltech produces plasmas where the shape is neither fixed by a vacuum chamber wall nor imposed by an external coil set, but rather is allowed to be determined by self-organizing MHD processes subject to the constraint of imposed boundary conditions analogous to the boundary conditions of space plasmas. These self-organizing processes are believed to be fundamental to astrophysical jets, solar coronal loops, and MHD turbulence (e.g. Taylor relaxation). The experimental dynamics are sufficiently reproducible to allow detailed study despite the morphology being complex and dynamic. A surprising result has been the observation that instead of the plasma uniformly filling up the available volume, the plasma is spatially localized in a highly collimated, small diameter magnetic flux tube, the length and axis of which change in time in response to MHD forces. A model shows that the collimation results from stagnation of linked magnetic flux frozen into a MHD-driven jet that accelerates plasma from the wall into the flux tube, filling the flux tube with plasma. Jet flow has been imaged with a high-speed multi-frame camera, diagnosed via Doppler spectroscopy, and most recently (i) the collision between two opposing, color-coded jets flowing from opposite ends of a flux tube has been observed, and (ii) the collision of a jet with a target cloud has been observed.

  10. 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.

  11. Portable nanosecond pulsed air plasma jet

    SciTech Connect

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

    2011-08-22

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

  12. Particle transport in pellet fueled JET (Jet European Torus) plasmas

    SciTech Connect

    Baylor, L.R.

    1990-01-01

    Pellet fueling experiments have been carried out on the Joint European Torus (JET) tokamak with a multi-pellet injector. The pellets are injected at speeds approaching 1400 m/s and penetrate deep into the JET plasma. Highly peaked electron density profiles are achieved when penetration of the pellets approaches or goes beyond the magnetic axis, and these peaked profiles persist for more than two seconds in ohmic discharges and over one second in ICRF heated discharges. In this dissertation, analysis of electron particle transport in multi-pellet fueled JET limiter plasmas under a variety of heating conditions is described. The analysis is carried out with a one and one-half dimensional radial particle transport code to model the experimental density evolution with various particle transport coefficients. These analyses are carried out in plasmas with ohmic heating, ICRF heating, and neural beam heating, in limiter configurations. Peaked density profile cases are generally characterized by diffusion coefficients with a central (r/a < 0.5) diffusivity {approximately}0.1 m{sup 2}/s that increases rapidly to {approximately}0.3 m{sup 2}/s at r/a = 0.6 and then increases out to the plasma edge as (r/a){sup 2}. These discharges can be satisfactorily modeled without any anomalous convective (pinch) flux. 79 refs., 60 figs.

  13. Inductive Measurement of Plasma Jet Electrical Conductivity

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  14. An experimental burn wound-healing study of non-thermal atmospheric pressure microplasma jet arrays.

    PubMed

    Lee, Ok Joo; Ju, Hyung Woo; Khang, Gilson; Sun, Peter P; Rivera, Jose; Cho, Jin Hoon; Park, Sung-Jin; Eden, J Gary; Park, Chan Hum

    2016-04-01

    In contrast with a thermal plasma surgical instrument based on coagulative and ablative properties, low-temperature (non-thermal) non-equilibrium plasmas are known for novel medicinal effects on exposed tissue while minimizing undesirable tissue damage. In this study we demonstrated that arrays of non-thermal microplasma jet devices fabricated from a transparent polymer can efficiently inactivate fungi (Candida albicans) as well as bacteria (Escherichia coli), both in vitro and in vivo, and that this leads to a significant wound-healing effect. Microplasma jet arrays offer several advantages over conventional single-jet devices, including superior packing density, inherent scalability for larger treatment areas, unprecedented material flexibility in a plasma jet device, and the selective generation of medically relevant reactive species at higher plasma densities. The therapeutic effects of our multi-jet device were verified on second-degree burns in animal rat models. Reduction of the wound area and the histology of the wound after treatment have been investigated, and expression of interleukin (IL)-1α, -6 and -10 was verified to evaluate the healing effects. The consistent effectiveness of non-thermal plasma treatment has been observed especially in decreasing wound size and promoting re-epithelialization through collagen arrangement and the regulation of expression of inflammatory genes.

  15. Local Heat Transfer Characteristics of Free-Surface Liquid Jets and Jet Arrays.

    NASA Astrophysics Data System (ADS)

    Pan, Yichuan

    1993-01-01

    Infrared radiometric techniques have been used to characterize local heat transfer for single free-surface liquid jets and arrays of free-surface liquid jets. The single-jet study deals with the effect of selected nozzle configurations on the local heat transfer in the stagnation zone, and is accompanied by a separate flow structure study. The results show that for identical jet Reynolds numbers, significant differences (as much as 40%) exist in the magnitudes of the local Nusselt number for the four nozzle configurations studied. Local heat transfer results reveal that for already turbulent jets, the dimensionless mean radial velocity gradient appears to be more influential in determining the heat transfer than changes in turbulence level. An empirical correlation of the experimental data supports this conclusion, and reveals that the stagnation Nusselt number is affected independently by the jet Reynolds number and the dimensionless mean radial velocity gradient. The multiple-jet study reveals local heat transfer characteristics of jet arrays. The different inter-jet flow interaction, as represented by different jet array configurations (the in-line array and the staggered array with different nozzle-to-nozzle spacings), shows negligible influence on local heat transfer under the central jet. The secondary stagnation Nusselt number between the adjacent jets is a direct consequence of the inter-jet flow interaction, and can be as high as 50% of the primary stagnation Nusselt number. Local and average heat transfer also show dependence on the nozzle-to-plate spacing. A correlation for average heat transfer is proposed.

  16. Laboratory plasma physics experiments using merging supersonic plasma jets

    SciTech Connect

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

    2015-04-01

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

  17. Laboratory Astrophysics and Collimated Stellar Outflows: The Production of Radiatively Cooled Hypersonic Plasma Jets

    NASA Astrophysics Data System (ADS)

    Lebedev, S. V.; Chittenden, J. P.; Beg, F. N.; Bland, S. N.; Ciardi, A.; Ampleford, D.; Hughes, S.; Haines, M. G.; Frank, A.; Blackman, E. G.; Gardiner, T.

    2002-01-01

    We present the first results of astrophysically relevant experiments where highly supersonic plasma jets are generated via conically convergent flows. The convergent flows are created by electrodynamic acceleration of plasma in a conical array of fine metallic wires (a modification of the wire array Z-pinch). Stagnation of plasma flow on the axis of symmetry forms a standing conical shock effectively collimating the flow in the axial direction. This scenario is essentially similar to that discussed by Cantó and collaborators as a purely hydrodynamic mechanism for jet formation in astrophysical systems. Experiments using different materials (Al, Fe, and W) show that a highly supersonic (M~20), well-collimated jet is generated when the radiative cooling rate of the plasma is significant. We discuss scaling issues for the experiments and their potential use for numerical code verification. The experiments also may allow direct exploration of astrophysically relevant issues such as collimation, stability, and jet-cloud interactions.

  18. Experiments with laser driven plasma jets

    NASA Astrophysics Data System (ADS)

    Nicolai, Philippe

    2008-04-01

    Laboratory studies can address issues relevant to astrophysics^1 and in some cases improve our understanding of the physical processes that occur in astrophysical objects. So issues related to the jet propagation and collimation over considerable distance and their interactions with surrounding media have begun to be addressed these last years. Laboratory plasmas and astrophysical objects have different length, time and density scales. However, the typical velocities are the same, of a few hundred km/s and the similarity criteria^2 can be applied to scale the laboratory jets to astrophysical conditions. In this presentation, we use a method of jet formation^3 which allows to launch a very fast jet having a velocity around 400 km/s by using a relatively small laser energy, of the order of 100 J. The jet has a Mach number greater than 10, a length of a few mm, and a radius of a few tenths of mm. The interaction of these jets with a gas puff has been recently studied in an experiment carried out at the PALS laser facility. Varying gas pressure and composition, we show that the nature of interaction zone changes from a quasi adiabatic outflow to a strongly radiatively cooling jet. The use of various diagnostics, allows to relate the x-ray emission to the density map of the interaction zone. Already observed in astrophysical objets for strongly different time and space scales, these structures are interpreted in our laboratory experiment by using a semi-analytical model and 2D radiation hydrodynamic simulations. [1] B. Remington et al, Rev. Mod. Phys. 78, 755 (2007) [2] D. Ryutov et al, Phys . Plasmas 8, 1804 (2001) [3] Ph. Nicolai et al, Phys. Plasmas 13, 062701 (2007)

  19. Improved Phased Array Imaging of a Model Jet

    NASA Technical Reports Server (NTRS)

    Dougherty, Robert P.; Podboy, Gary G.

    2010-01-01

    An advanced phased array system, OptiNav Array 48, and a new deconvolution algorithm, TIDY, have been used to make octave band images of supersonic and subsonic jet noise produced by the NASA Glenn Small Hot Jet Acoustic Rig (SHJAR). The results are much more detailed than previous jet noise images. Shock cell structures and the production of screech in an underexpanded supersonic jet are observed directly. Some trends are similar to observations using spherical and elliptic mirrors that partially informed the two-source model of jet noise, but the radial distribution of high frequency noise near the nozzle appears to differ from expectations of this model. The beamforming approach has been validated by agreement between the integrated image results and the conventional microphone data.

  20. Measurements of railgun generated supersonic plasma jet propagation and two jet oblique merging

    NASA Astrophysics Data System (ADS)

    Merritt, Elizabeth C.

    Imploding spherical plasma liners have been proposed as a possible method for creating high-energy-density (HED) laboratory plasmas and as a standoff driver for magneto-inertial fusion (MIF). The Plasma Liner Experiment (PLX) planned a three-phase experimental program to study the feasibility of using railgun-driven supersonic jets to form imploding spherical plasma liners. The three phases are to investigate single-jet evolution during propagation, to merge 2-5 jets to assess the suitability of merging for liner formation, and to merge 30 jets in spherical symmetry to form a complete liner. We present here details of single-jet propagation and two-jet oblique merging experiments completed on PLX. A key component of this dissertation was the design, implementation, and operation of a novel 8 chord, fiber-coupled interferometer based on a long coherence length (> 100 m) 561 nm diode-pumped solid state laser. This interferometer was a critical diagnostic in both single-jet propagation and two-jet merging studies. The long laser coherence length and fiber-optic design allowed signal and reference path lengths in the interferometer to be mismatched by many meters without signal degradation, greatly simplified interferometer optical layout, and added flexibility in interferometer positioning for both propagation and merging experiments. The interferometer sensitivity to ions, neutral atoms, and electrons required development of a phase shift analysis that incorporated the presence of neutrals, impurities, and multiply ionized species. Interferometry, coupled with spectroscopic ionization fraction estimates, was used to assess time resolved density profile measurements. Survey spectroscopy inferred both Te and ionization fraction f via non-local-thermodynamic-equilibrium (non-LTE) atomic/equation-of-state (EOS) modeling. A fast CCD camera and photo-diode array allowed for assessment of plasma emission for velocity and jet profile measurements. Initial jet parameters were

  1. Magnetic Field Measurements Inside a Supersonic Plasma Jet Formed by a Pulsed Railgun

    NASA Astrophysics Data System (ADS)

    Martens, D.; Hsu, S. C.

    2012-10-01

    The Plasma Liner Experiment (PLX) at Los Alamos National Laboratory (LANL) was designed to create a spherically imploding plasma liner via the merging of 30 supersonic plasma jets formed by pulsed plasma railguns. The propagation and merging of two plasma jets is being studied via spectroscopy, a photodiode array, and interferometry to analyze plasma temperature, velocity, density, and ionization fraction of the evolving jets. Although the magnetic field strength is known to be strong (>1 T) within the bore of the plasma railgun, no measurements have been made of the field in the jet once it propagates away from the gun. Based on the expected jet radius (˜5 cm) and temperature (˜1 eV) near the exit of the gun, the classical diffusion time of the field (˜3 μs) is expected to be short enough such that the field will be very small by the time the jets propagate a few tens of centimeters. This work presents the design of a magnetic probe array to measure the magnetic field vectors at 5 and 30 cm from the plasma gun nozzle, and also the initial experimental results from the magnetic probe diagnostic.

  2. Large area atmospheric-pressure plasma jet

    DOEpatents

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

    2001-01-01

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

  3. Generating and controlling homogeneous air turbulence using random jet arrays

    NASA Astrophysics Data System (ADS)

    Carter, Douglas; Petersen, Alec; Amili, Omid; Coletti, Filippo

    2016-12-01

    The use of random jet arrays, already employed in water tank facilities to generate zero-mean-flow homogeneous turbulence, is extended to air as a working fluid. A novel facility is introduced that uses two facing arrays of individually controlled jets (256 in total) to force steady homogeneous turbulence with negligible mean flow, shear, and strain. Quasi-synthetic jet pumps are created by expanding pressurized air through small straight nozzles and are actuated by fast-response low-voltage solenoid valves. Velocity fields, two-point correlations, energy spectra, and second-order structure functions are obtained from 2D PIV and are used to characterize the turbulence from the integral-to-the Kolmogorov scales. Several metrics are defined to quantify how well zero-mean-flow homogeneous turbulence is approximated for a wide range of forcing and geometric parameters. With increasing jet firing time duration, both the velocity fluctuations and the integral length scales are augmented and therefore the Reynolds number is increased. We reach a Taylor-microscale Reynolds number of 470, a large-scale Reynolds number of 74,000, and an integral-to-Kolmogorov length scale ratio of 680. The volume of the present homogeneous turbulence, the largest reported to date in a zero-mean-flow facility, is much larger than the integral length scale, allowing for the natural development of the energy cascade. The turbulence is found to be anisotropic irrespective of the distance between the jet arrays. Fine grids placed in front of the jets are effective at modulating the turbulence, reducing both velocity fluctuations and integral scales. Varying the jet-to-jet spacing within each array has no effect on the integral length scale, suggesting that this is dictated by the length scale of the jets.

  4. Artificial plasma jet in the ionosphere

    NASA Astrophysics Data System (ADS)

    Haerendel, G.; Sagdeev, R. Z.

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

  5. Laboratory plasma physics experiments using merging supersonic plasma jets

    DOE PAGES

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

    2015-04-01

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

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

    SciTech Connect

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

    2009-04-15

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

  7. Plasma diagnostics of non-equilibrium atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  8. Magnetized plasma jets in experiment and simulation

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  9. Development of atmospheric pressure large area plasma jet for sterilisation and investigation of molecule and plasma interaction

    NASA Astrophysics Data System (ADS)

    Zerbe, Kristina; Iberler, Marcus; Jacoby, Joachim; Wagner, Christopher

    2016-09-01

    The intention of the project is the development and improvement of an atmospheric plasma jet based on various discharge forms (e.g. DBD, RF, micro-array) for sterilisation of biomedical equipment and investigation of biomolecules under the influence of plasma stress. The major objective is to design a plasma jet with a large area and an extended length. Due to the success on small scale plasma sterilisation the request of large area plasma has increased. Many applications of chemical disinfection in environmental and medical cleaning could thereby be complemented. Subsequently, the interaction between plasma and biomolecules should be investigated to improve plasma strerilisation. Special interest will be on non equilibrium plasma electrons affecting the chemical bindings of organic molecules.

  10. Magnetized laboratory plasma jets: experiment and simulation.

    PubMed

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

    2015-01-01

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

  11. Living tissue under treatment of cold plasma atmospheric jet

    SciTech Connect

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

    2008-11-03

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

  12. Bacterial Inactivation by Atmospheric Pressure Dielectric Barrier Discharge Plasma Jet

    NASA Astrophysics Data System (ADS)

    Deng, Sanxi; Cheng, Cheng; Ni, Guohua; Meng, Yuedong; Chen, Hua

    2008-08-01

    Bacillus subtilis and Escherichia coli seeded in two media (agar and filter papers) were exposed to after-glow plasma emitted from a atmospheric pressure dielectric barrier discharge (DBD) plasma jet generator in open air with a temperature of about 30-80 °C. In order to estimate the inactivation of microorganism using DBD plasma jet, various plasma conditions (such as treatment time and feed-gas composition of plasma jet) were changed. The results shown that the effective area of inactivation increased with the plasma treatment time as the bacteria seeded in Agar medium. The effective area of inactivation was much bigger than plasma jet treatment area after 5 min treatment. With the use of filter papers as the supporting media, the addition of reactive gases (oxygen, hydrogen peroxide vapor) into the plasma jet system, compared with only pure noble gas, led to a significant improvement in the bacterial Inactivation efficacy.

  13. Plasma waves and jets from moving conductors

    NASA Astrophysics Data System (ADS)

    Gralla, Samuel E.; Zimmerman, Peter

    2016-06-01

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

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

    SciTech Connect

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

    2012-01-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  16. MTF Driven by Plasma Liner Dynamically Formed by the Merging of Plasma Jets: An Overview

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Eskridge, Richard; Martin, Adam; Smith, James; Lee, Michael; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    One approach for standoff delivery of the momentum flux for compressing the target in MTF consists of using a spherical array of plasma jets to form a spherical plasma shell imploding towards the center of a magnetized plasma, a compact toroid (Figure 1). A 3-year experiment (PLX-1) to explore the physics of forming a 2-D plasma liner (shell) by merging plasma jets is described. An overview showing how this 3-year project (PLX-1) fits into the program plan at the national and international level for realizing MTF for energy and propulsion is discussed. Assuming that there will be a parallel program in demonstrating and establishing the underlying physics principles of MTF using whatever liner is appropriate (e.g. a solid liner) with a goal of demonstrating breakeven by 2010, the current research effort at NASA MSFC attempts to complement such a program by addressing the issues of practical embodiment of MTF for propulsion. Successful conclusion of PLX-1 will be followed by a Physics Feasibility Experiment (PLX-2) for the Plasma Liner Driven MTF.

  17. MTF Driven by Plasma Liner Dynamically Formed by the Merging of Plasma Jets: An Overview

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Eskridge, Richard; Martin, Adam; Smith, James; Lee, Michael; Rodgers, Stephen L. (Technical Monitor)

    2001-01-01

    One approach for standoff delivery of the momentum flux for compressing the target in MTF consists of using a spherical array of plasma jets to form a spherical plasma shell imploding towards the center of a magnetized plasma, a compact toroid (Figure 1). A 3-year experiment (PLX-1) to explore the physics of forming a 2-D plasma liner (shell) by merging plasma jets is described. An overview showing how this 3-year project (PLX-1) fits into the program plan at the national and international level for realizing MTF for energy and propulsion is discussed. Assuming that there will be a parallel program in demonstrating and establishing the underlying physics principles of MTF using whatever liner is appropriate (e.g. a solid liner) with a goal of demonstrating breakeven by 2010, the current research effort at NASA MSFC attempts to complement such a program by addressing the issues of practical embodiment of MTF for propulsion. Successful conclusion of PLX-1 will be followed by a Physics Feasibility Experiment (PLX-2) for the Plasma Liner Driven MTF.

  18. Jet noise control using the dielectric barrier discharge plasma actuators

    NASA Astrophysics Data System (ADS)

    Kopiev, V. F.; Bityurin, V. A.; Belyaev, I. V.; Godin, S. M.; Zaitsev, M. Yu.; Klimov, A. I.; Kopiev, V. A.; Moralev, I. A.; Ostrikov, N. N.

    2012-07-01

    We study experimentally how plasma actuators operating on the basis of surface barrier high-frequency discharge affect jet noise characteristics. The results of investigations of air jets (100-200 m/s) have demonstrated that the studied plasma actuators have control authority over the noise characteristics of these jets. An actuator's effect on the jet in the applied configuration is related to acoustic discharge excitation and to a large extent is similar to the well-known Vlasov-Ginevsky effect. It has been shown that jet excitation in the case of St ˜ 0.5 using the barrier-discharge plasma actuator leads to broadband amplification of jet sound radiation. The jet excitation in the case of St > 2 leads to broadband noise reduction if the action is sufficiently intensive.

  19. Ion-viscosity effects on plasma-liner formation and implosion via merging supersonic plasma jets

    NASA Astrophysics Data System (ADS)

    Schillo, Kevin; Cassibry, Jason; Samulyak, Roman; Shih, Wen; Hsu, Scott; PLX-Alpha Team

    2016-10-01

    The PLX- α project endeavors to study plasma-liner formation and implosion by merging a spherical array of plasma jets as a candidate standoff driver for MIF. Smoothed particle hydrodynamics is used to model the liner formation and implosion processes. SPH is a meshless Lagrangian method to simulate fluid flows by dividing a fluid into a set of particles and using a summation interpolant function to calculate the properties and gradients for each of these particles. Ion viscosity is anticipated to be an important mechanism for momentum transport during liner formation, implosion, and stagnation. To study this, ion viscosity was incorporated into the code. To provide confidence in the numerical output and to help identify the difference between numerical and physical diffusion, a series of test cases were performed, consisting of Couette flow, Gresho vortex, and a Taylor-Green vortex. An L2-norm analysis was performed to measure the error and convergence. Simulations of conical (6 jets) and 4 π (60 jets) liners with and without ion viscosity reveal potential effects of viscosity on ram pressure, Mach-number degradation, and evolution of liner perturbations during jet merging and liner implosion.

  20. Laboratory astrophysics: 2D and 3D numerical modeling of jets and flows produced in wire array experiments

    NASA Astrophysics Data System (ADS)

    Ciardi, A.; Lebedev, S. V.; Ampleford, D. J.; Chittenden, J. P.; Bland, S. N.; Sherlock, M.; Rapley, J.; Bott, S. C.; Jennings, C.

    2004-04-01

    Numerical modeling of jets formed in conical wire array Z-pinch experiments shows that scaled, astrophysically relevant flows can be obtained in the laboratory. These jets are hypersonic, with Mach number in excess of 20, are radiatively cooled and have a length to width ratio of ~ 1:10. Furthermore the jet formation mechanism is due to the hydrodynamic confinement of a standing conical shock, which redirects and collimates the converging plasma flow. The jets produced are also characterized by large Reynolds and Peclet numbers. Jet-wind interactions are modeled assuming a supersonically expanding radiatively ablated plasma wind. The jet bends away from the wind and it remains well collimated during and after the interaction, with the bending determined by the ram pressure of the impinging wind. A further development in wire array laboratory astrophysics experiments is the use of radial arrays, where the interaction of a ``freely'' expanding toroidal-like plasma cloud produces an axial collimated flow; subsequently a strong shock drives a supersonic, high density radiatively cooled ``bullet'' through this background medium.

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

    SciTech Connect

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

    2014-06-16

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

  2. Characteristics of Plasma Jet by using the Modified Pseudospark Discharge

    NASA Astrophysics Data System (ADS)

    Watanabe, Masayuki; Kamada, Takaharu; Itagaki, Minoru; Ishikawa, Toshiaki

    2000-10-01

    Pseudospark discharge (PSD) is one of the low-pressure gas discharges. In PSD, the parallel plane electrodes are replaced by that with a circular hole on the axis. This cathode has a cylindrical cavity behind the circular hole. PSD can be formed by using such modified electrodes in the low-pressure region under the Paschen minimum. PSD is characterized as follows: (1)Discharge is formed through the holes of electrode. (2)Breakdown voltage is a function of plasma pressure. (3)Since the hollow cathode effect, high current glow discharge can be formed. (4)Damage of electrode is low. We have been studying the plasma jet by using the modified PSD. In this plasma jet, diameter of anode hole is widened in comparison with that of cathode hole. The force of plasma acceleration is Lorentz force, which is similar to that of MPD arc jet. This plasma jet is characterized as follows: (1)Plasma is spouted at high speed (2)High temperature plasma will be formed due to the high current discharge. (3)Since the damage of electrodes is low, lifetime of the device is long. (4)Strong magnetic field with the plasma jet generates. This strong magnetic field may be possible to transport with plasma jet. In this poster, the space distribution of plasma jet and lifetime of electrode are reported in detail.

  3. Microwave-excited atmospheric-pressure plasma jets using a microstrip line

    SciTech Connect

    Kim, Jaeho; Katsurai, Makoto; Kim, Dongmin; Ohsaki, Hyroyuki

    2008-11-10

    We report a 2.45 GHz microwave-excited atmospheric-pressure plasma jet (MW-APPJ) device using a microstrip line for materials processing. A three-dimensional simulation based on the finite difference time domain method revealed that the configuration of the MW-APPJ device results in a strong concentration of electric fields at the gas nozzle. Argon plasmas were generated at the nozzle and were blown into ambient air with the maximum length of 5 mm at a microwave power of 40 W. The rotational temperatures of molecular nitrogen in the downstream of the plasma jets, measured by optical emission spectroscopy, were 1720 to 900 K for gas flow rates from 0.5 to 3.5 l/min, indicating that the jets were nonthermal plasmas. This MW-APPJ device will provide a large-area APPJ for materials processing depending on the configuration of the nozzle array and microstrip lines.

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

    SciTech Connect

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

    2005-07-13

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

  5. The evolution of atmospheric-pressure low-temperature plasma jets: jet current measurements

    NASA Astrophysics Data System (ADS)

    Karakas, Erdinc; Arda Akman, Mehmet; Laroussi, Mounir

    2012-06-01

    In this study, we report insights into the dynamics of atmospheric-pressure low-temperature plasma jets (APLTPJs). The plasma jet current was measured by a Pearson current monitor for different operating conditions. These jet current measurements confirmed a proposed photo-ionization model based on streamer theory. Our results are supported by intensified charged-couple device camera observations. It was found that a secondary discharge ignition, arising from the positive high-voltage electrode, causes the inhibition of plasma bullet propagation. Our observations also showed the existence of an ionization channel between the APLTPJ reactor and the plasma bullet. In addition, the maximum electron density along the plasma jet was estimated using Ohm's law, and an empirical relationship was derived between the plasma bullet velocity and the plasma bullet area.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  7. Probing Runaway Electrons with Nanoparticle Plasma Jet

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    The injection of C60/C nanoparticle plasma jet (NPPJ) into tokamak plasma during a major disruption has the potential to probe the runaway electrons (REs) during different phases of their dynamics and diagnose them through spectroscopy of C ions visible/UV lines. A C60/C NPPJ of ~75 mg, high-density (>1023 m-3), hyper-velocity (>4 km/s), and uniquely fast response-to-delivery time (~1 ms) has been demonstrated on a test bed. It can rapidly and deeply deliver enough mass to increase electron density to ~2.4 × 1021 m-3, ~60 times larger than typical DIII-D pre-disruption value. We will present the results of our investigations on: 1) C60 fragmentation and gradual release of C atoms along C60 NPPJ penetration path through the RE carrying residual cold plasma, 2) estimation of photon emissivity coefficient for the lines of the C ions, and 3) simulation of C60/C PJ penetration to the RE beam location in equivalent conditions to the characteristic ~1 T B-field of DIII-D. The capabilities of this injection technique provide a unique possibility in understanding and controlling the RE beam, which is a critical problem for ITER. Work supported by US DOE DE-SC0011864 Grant.

  8. Cellular membrane collapse by atmospheric-pressure plasma jet

    SciTech Connect

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

    2014-01-06

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

  9. Cellular membrane collapse by atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kim, Kangil; Jun Ahn, Hak; Lee, Jae-Hyeok; Kim, Jae-Ho; Sik Yang, Sang; Lee, Jong-Soo

    2014-01-01

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

  10. Low temperature atmospheric microplasma jet array for uniform treatment of polymer surface for flexible electronics

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Wang, Xiaolin; Yang, Bin; Chen, Xiang; Yang, Chunsheng; Liu, Jingquan

    2017-07-01

    In this paper, the uniformity of polymer film etching by an atmospheric pressure He/O2 microplasma jet array (μPJA) is first investigated with different applied voltage. Plasma characteristics of μPJA were recorded by optical discharge images. Morphologies and chemical compositions of polymer film etched by μPJA were analyzed by optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS). By increasing the applied voltage from 8.5 kV to 16.4 kV, the non-uniformity of the luminous intensity of the plasma jets increases. It is interesting that the plasma treated regions are actually composed of an etched region and modification region, with distinct morphologies and chemical compositions. The diameters of the etched parylene-C film show the increase of non-uniformity with higher applied voltage. SEM results show that the non-uniformity of surface morphologies of both the modification regions and etched regions increases with the increase of applied voltage. EDS and XPS results also present the significant effect of higher applied voltage on the non-uniformity of surface chemical compositions of both modification and etched regions. The Coulomb interaction of the streamer heads and the hydrodynamic interaction between the plasma jets and the surrounding air are considered to be responsible for this phenomenon. The results shown in this work can help improve the processing quality of polymer film etched by an atmospheric pressure microplasma jet array and two applications are demonstrated to illustrate the uniform downstream surface treatment.

  11. observation of auroral emissions induced by artificial plasma jets

    NASA Astrophysics Data System (ADS)

    Erlandson, R. E.; Swaminathan, P. K.; Meng, C.-I.; Stoyanov, B. J.; Zetzer, J. I.; Gavrilov, B. G.; Kiselev, Yu. N.; Romanovsky, Yu. A.

    In this paper we present ultraviolet to near infrared spectrographic observations of high-speed artificial plasma jet interactions with the ionosphere. The plasma jets were injected quasi-parallel to the magnetic field at an altitude of 140 km during the Fluxus-1 and -2 experiments. The jets contained aluminum ions and were generated using a shaped-charge device known as an Explosive Type Generator (ETG). Satellite-based spectrographic observations of the plasma jet show typical auroral emission features associated with electron impact excitation. The auroral features include emission at 135.6 nm (OI) and 557.7 nm (OI). The 135.6 nm emission was prompt while the 557.7 nm was observed for 5 seconds. The most likely source of these auroral emissions are ionospheric and magnetospheric electrons that neutralize the plasma jet.

  12. 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.

  13. Supersonic gas jets for laser-plasma experiments.

    PubMed

    Schmid, K; Veisz, L

    2012-05-01

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

  14. Plasma-induced flow instabilities in atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Lietz, Amanda M.; Johnsen, Eric; Kushner, Mark J.

    2017-09-01

    Pulsed plasma excitation of rare gases flowing into air has been shown to impact the stability of the flow in non-equilibrium atmospheric pressure plasma jets (APPJs). In this paper, the results from a numerical modeling investigation of the stability of a round He APPJ with a powered electrode exposed to the gas flow are discussed. Localized gas heating at the powered electrode occurs on the time scale of the voltage pulse, tens to 100 ns, which is short compared to the fluid timescales. An acoustic wave propagates from this heated, expanding gas and exits the jet. The wave disturbs the shear layer between the He and surrounding humid air, exciting a shear instability which grows downstream with the flow and increases the mixing of the humid air into the He. The effects of the eddy-dominated flow on ionization wave (IW) propagation in an APPJ were investigated. The IW followed the regions of the highest helium concentration, resulting in an increased production of NO, HO2, and NO2.

  15. Inactivation of Escherichia coli using atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kuwahata, Hiroshi; Yamaguchi, Takeshi; Ohyama, Ryu-ichiro; Ito, Atsushi

    2015-01-01

    An atmospheric-pressure argon (Ar) plasma jet was applied to the inactivation of Escherichia coli. The Ar plasma jet was generated at a frequency of 10 kHz, an applied voltage of 10 kV, and an Ar gas flow rate of 10 L/min at atmospheric pressure. E. coli cells seeded on an agar medium in a Petri dish were inactivated by Ar plasma jet irradiation for 1 s. Scanning electron microscopy (SEM) revealed that E. coli cells were killed because their cell wall and membrane were disrupted. To determine the causes of the disruption of the cell wall and membrane of E. coli, we performed the following experiments: the measurement of the surface temperature of an agar medium using a thermograph, the analysis of an emission spectrum of a plasma jet obtained using a multichannel spectrometer, and the determination of the distribution of the concentration of hydrogen peroxide (H2O2) generated on an agar medium by plasma jet irradiation using semiquantitative test strips. Moreover, H2O2 solutions of different concentrations were dropped onto an agar medium seeded with E. coli cells to examine the contribution of H2O2 to the death of E. coli. The results of these experiments showed that the cell wall and membrane of E. coli were disrupted by electrons in the plasma jet, as well as by electroneutral excited nitrogen molecules (N2) and hydroxyl (OH) radicals in the periphery of the plasma jet.

  16. [Spectral diagnosis of plasma jet at atmospheric pressure].

    PubMed

    Li, Chi; Tang, Xiao-liang; Qiu, Gao

    2008-12-01

    A new approach to surface modification of materials using dielectric barrier discharge (DBD) plasma jet at atmospheric pressure is presented in the present paper. The emission spectral lines of argon plasma jet at atmospheric pressure were recorded by the grating spectrograph HR2000 and computer software. The argon plasma emission spectra, ranging from 300nm to 1000 nm, were measured at different applied voltage. Compared to air plasma emission spectra under the same circumstance, it is shown that all of the spectral lines are attributed to neutral argon atoms. The spectral lines 763.51 and 772.42 nm were chosen to estimate the electron excitation temperature. The purpose of the study is to research the relationship between the applied voltage and temperature to control the process of materials' surface modification promptly. The results show that electron excitation temperature is in the range of 0.1-0.5 eV and increases with increasing applied voltage. In the process of surface modification under the plasma jet, the infrared radiation thermometer was used to measure the material surface temperature under the plasma jet. The results show that the material surface temperature is in the range of 50-100 degrees C and it also increases with increasing applied voltage. Because the material surface was under the plasma jet and its temperature was decided by the plasma, and the material surface temperature increased with increasing the macro-temperature of plasma jet, the relationship between the surface temperature and applied voltage indicates the relationship between the macro-temperature of the plasma jet and the applied voltage approximately. The experimental results indicate that DBD plasma jet at atmospheric pressure is a new approach to improving the quality of materials' surface modification, and spectral diagnosis has proved to be a kind of workable method by choosing suitable applied voltage.

  17. Electrode Configurations in Atmospheric Pressure Plasma Jets

    NASA Astrophysics Data System (ADS)

    Lietz, Amanda M.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure plasma jets (APPJs) are being studied for emerging medical applications including cancer treatment and wound healing. APPJs typically consist of a dielectric tube through which a rare gas flows, sometimes with an O2 or H2O impurity. In this paper, we present results from a computational study of APPJs using nonPDPSIM, a 2-D plasma hydrodynamics model, with the goal of providing insights on how the placement of electrodes can influence the production of reactive species. Gas consisting of He/O2 = 99.5/0.5 is flowed through a capillary tube at 2 slpm into humid air, and a pulsed DC voltage is applied. An APPJ with two external ring electrodes will be compared with one having a powered electrode inside and a ground electrode on the outside. The consequences on ionization wave propagation and the production of reactive oxygen and nitrogen species (RONS) will be discussed. Changing the electrode configuration can concentrate the power deposition in volumes having different gas composition, resulting in different RONS production. An internal electrode can result in increased production of NOx and HNOx by increasing propagation of the ionization wave through the He dominated plume to outside of the tube where humid air is diffusing into the plume. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  18. Generation of reactive species by an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kelly, S.; Turner, M. M.

    2014-12-01

    The role of gas mixing in reactive species delivery to treatment surfaces for an atmospheric pressure capacitively coupled plasma helium jet is investigated by numerical modelling. Atomic oxygen in the jet effluent is shown to quickly convert to ozone for increasing device to surface separation due to the molecular oxygen present in the gas mixture. Surface profiles of reactive oxygen species show narrow peaks for atomic oxygen and broader surface distributions for ozone and metastable species. Production efficiency of atomic oxygen to the helium plasma jet by molecular oxygen admixture is shown to be dependent on electro-negativity. Excessive molecular oxygen admixture results in negative ion dominance over electrons which eventually quenches the plasma. Interaction of the plasma jet with an aqueous surface showed hydrogen peroxide as the dominant species at this interface. Gas heating by the plasma is found to be dominated by elastic electron collisions and positive ion heating. Comparison with experimental measurements for atomic oxygen shows good agreement.

  19. Plasma Jet Interaction with Thomson Scattering Probe Laser

    NASA Astrophysics Data System (ADS)

    Byvank, Tom; Banasek, Jacob; Potter, William; Kusse, Bruce

    2016-10-01

    Thomson scattering systems can diagnose plasma temperatures and velocities. When probing a plasma jet with the Thomson scattering laser, we observe a laser-plasma interaction that inputs energy into the plasma jet. The absorbed energy causes a bubble of low density ( 5*1017 cm-2) in the jet (unperturbed 1018 cm-2). A pulsed power machine (1 MA peak current, 100 ns rise time) with a radial foil (15 μm thick Al) configuration generates the plasma jet. We compare the effects of using 10 J and 1 J laser energies, for which the 10 J laser is a larger perturbation. We discuss how the interaction affects the Thomson scattering temperature and velocity measurements. Work supported by National Nuclear Security Administration (NNSA) Stewardship Sciences Academic Programs under Department of Energy (DOE) Cooperative Agreement DE-NA0001836 and National Science Foundation (NSF) Grant PHY-1102471.

  20. Three electrode atmospheric pressure plasma jet in helium flow

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  1. Visualization of jet development in laser-induced plasmas.

    PubMed

    Brieschenk, Stefan; O'Byrne, Sean; Kleine, Harald

    2013-03-01

    Laser-induced plasmas in gases are known to generate gaseous jets in the postplasma gas plume. The gaseous jet typically develops toward the laser source, and the experiments presented here show, for the first time to our knowledge, that, under certain conditions, these jets can develop in the opposite direction or may not form at all. The data suggest that this is related to the ratio between the energy absorbed in the plasma and the threshold breakdown energy, effectively leading to multiple plasma initiation sites in the focal waist.

  2. Investigation of MHD Instabilities in Jets and Bubbles Using a Compact Coaxial Plasma Gun in a Background Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Fisher, D. M.; Wallace, B.; Gilmore, M.; Hsu, S. C.

    2016-10-01

    A compact coaxial plasma gun is employed for experimental investigation of launching plasma into a lower density background magnetized plasma. Experiments are being conducted in the linear device HelCat at UNM. Four distinct operational regimes with qualitatively different dynamics are identified by fast CCD camera images. For regime I plasma jet formation, a global helical magnetic configuration is determined by a B-dot probe array data. Also the m =1 kink instability is observed and verified. Furthermore, when the jet is propagating into background magnetic field, a longer length and lifetime jet is formed. Axial shear flow caused by the background magnetic tension force contributes to the increased stability of the jet body. In regime II, a spheromak-like plasma bubble formation is identified when the gun plasma is injected into vacuum. In contrast, when the bubble propagates into a background magnetic field, the closed magnetic field configuration does not hold anymore and a lateral side, Reilgh-Taylor instability develops. Detailed experimental data and analysis will be presented for these cases.

  3. Removal of floating dust in glow discharge using plasma jet

    SciTech Connect

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

    2010-07-05

    Dust can be an inconvenient source of impurities in plasma processing reactors and in many cases it can cause damage to the plasma-treated surfaces. A technique for dust expulsion out of the trapping region in plasma is presented here, based on the wind force exerted on dust particles by a pulsed plasma jet. Its applicability is demonstrated by removing floating dust in the sheath of parallel-plate capacitive radio-frequency plasma.

  4. Phased-Array Measurements of Single Flow Hot Jets

    NASA Technical Reports Server (NTRS)

    Bridges, James; Lee, Sang Soo

    2005-01-01

    A 16 microphone phased-array system has been successfully applied to measure jet noise source distributions. In this study, a round convergent nozzle was tested at various hot and cold flow conditions: acoustic Mach numbers are between 0.35 and 1.6 and static temperature ratios are varied from cold to 2.7. The classical beamforming method was applied on narrowband frequencies. From the measured source distributions locations of peak strength were tracked and found to be very consistent between adjacent narrowband frequencies. In low speed heated and unheated jets, the peak source locations vary smoothly from the nozzle exit to downstream as the frequency is decreased. When the static temperature ratio was kept constant, the peak source position moved downstream with increasing acoustic Mach number for the Strouhal numbers smaller than about 1.5. It was also noted that the peak source locations of low frequencies occur farther downstream than the end of potential core.

  5. Eulerian and Lagrangian Plasma Jet Modeling for the Plasma Liner Experiment

    NASA Astrophysics Data System (ADS)

    Hatcher, Richard; Cassibry, Jason; Stanic, Milos; Loverich, John; Hakim, Ammar

    2011-10-01

    The Plasma Liner Experiment (PLX) aims to demonstrate the feasibility of using spherically-convergent plasma jets to from an imploding plasma liner. Our group has modified two hydrodynamic simulation codes to include radiative loss, tabular equations of state (EOS), and thermal transport. Nautilus, created by TechX Corporation, is a finite-difference Eulerian code which solves the MHD equations formulated as systems of hyperbolic conservation laws. The other is SPHC, a smoothed particle hydrodynamics code produced by Stellingwerf Consulting. Use of the Lagrangian fluid particle approach of SPH is motivated by the ability to accurately track jet interfaces, the plasma vacuum boundary, and mixing of various layers, but Eulerian codes have been in development for much longer and have better shock capturing. We validate these codes against experimental measurements of jet propagation, expansion, and merging of two jets. Precursor jets are observed to form at the jet interface. Conditions that govern evolution of two and more merging jets are explored.

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

    NASA Astrophysics Data System (ADS)

    Ebersohn, F.; Shebalin, J. V.; Girimaji, S. S.

    2012-12-01

    Plasma jets are important physical phenomena in astrophysics and plasma propulsion devices. A currently proposed dual jet plasma propulsion device to be used for ISS experiments strongly resembles a coronal loop and further draws a parallel between these physical systems [1]. To study plasma jets we use numerical methods which solve the compressible MHD equations using the generalized Ohm's law[2]. Herein we discuss the crucial underlying physics of these systems along with the numerical procedures we utilize to study them. Recent results from our numerical experiments will be presented and discussed. [1] T. Glover, et al., The VASIMR® VF-200-1 ISS Experiment as a Laboratory for Astrophysics, Poster SM51C-1831, AGU Fall Meeting, San Francisco, December 13-17, 2010. [2] F. Ebersohn, J. V Shebalin, S. Girimaji and D. Staack, Magnetic Field Effects on Plasma Plumes, Paper O2-404, 39th EPS Conference on Plasma Physics, Stockholm, July 2-6, 2012.;

  7. The effect of working gas impurities on plasma jets

    SciTech Connect

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

    2015-04-15

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

  8. Plasma formation and dynamics in conical wire arrays in the Llampudken pulsed power generator

    SciTech Connect

    Muñoz, C. Gonzalo E-mail: fveloso@fis.puc.cl; Valenzuela, Vicente E-mail: fveloso@fis.puc.cl; Veloso, Felipe E-mail: fveloso@fis.puc.cl; Favre, Mario E-mail: fveloso@fis.puc.cl; Wyndham, Edmund E-mail: fveloso@fis.puc.cl

    2014-12-15

    Plasma formation and dynamics from conical wire array is experimentally studied. Ablation from the wires is observed, forming plasma accumulation at the array axis and subsequently a jet outflow been expelled toward the top of the array. The arrays are composed by 16 equally spaced 25μ diameter tungsten wires. Their dimensions are 20mm height, with base diameters of 8mm and 16mm top diameter. The array loads are design to be overmassed, hence no complete ablation of the wires is observed during the current rise. The experiments have been carried out in the Llampudken. pulsed power generator (∼350kA in ∼350ns). Plasma dynamics is studied in both side-on and end-on directions. Laser probing (shadowgraphy) is achieved using a frequency doubled Nd:YAG laser (532nm, 12ps FWHM) captured by CCD cameras. Pinhole XUV imaging is captured using gated microchannel plate cameras with time resolution ∼5ns. Results on the jet velocity and the degree of collimation indicating the plausibility on the use of these jets as comparable to the study astrophysically produced jets are presented and discussed.

  9. Etching of silicon surfaces using atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

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

    SciTech Connect

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

    1995-12-31

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

  12. A 1D (radial) Plasma Jet Propagation Study for the Plasma Liner Experiment (PLX)

    NASA Astrophysics Data System (ADS)

    Thompson, J. R.; Bogatu, I. N.; Galkin, S. A.; Kim, J. S.; Welch, D. R.; Thoma, C.; Golovkin, I.; Macfarlane, J. J.; Case, A.; Messer, S. J.; Witherspoon, F. D.; Cassibry, J. T.; Awe, T. J.; Hsu, S. C.

    2011-10-01

    The Plasma Liner Experiment will explore the formation of imploding spherical ``plasma liners'' that reach peak pressures of 0.1 Mbar upon stagnation. The liners will be formed through the merging of dense, high velocity plasma jets (n ~1017 cm-3, T ~3 eV, v ~50 km/s) in a spherically convergent geometry. The focus of this 1D (radial) study is argon plasma jet evolution during propagation from the rail gun source to the jet merging radius. The study utilizes the Large Scale Plasma (LSP) PIC code with atomic physics included through the use of a non-Local Thermal Equilibrium (NLTE) Equation of State (EOS) table. We will present scenarios for expected 1D (radial) plasma jet evolution, from upon exiting the PLX rail gun to reaching the jet merging radius. The importance of radiation cooling early in the simulation is highlighted. Work supported by US DOE grant DE-FG02-05ER54835.

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

    SciTech Connect

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

    2015-11-07

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

  14. Characterization of the evolution of underwater DBD plasma jet

    NASA Astrophysics Data System (ADS)

    Foster, John; Sommers, Bradley; Weatherford, Brandon; Yee, Benjamin; Gupta, Mahima

    2011-06-01

    An air plasma jet formed underwater using a coaxial DBD electrode configuration with gas flow is being studied for water treatment applications. The arc-like behavior of the discharge in the absence of any obvious return electrode is not well understood. This study seeks to understand the underlying nature of the arc-like jet mode by studying the evolution of the discharge from microdischarge to jet mode. Photographic and spectroscopic data are used to develop a phenomenological model of discharge evolution. Time-averaged spectra were used to assign an average plume and electron temperature. Calculated jet temperatures were consistent with observed affects such as melting and oxide layer formation on a downstream substrate. The capacity of the microdischarge mode to decompose organic dye in water as a function of time, confirmed previously in the jet mode, was also demonstrated in the absence of the jet.

  15. Optimizing Dense Plasma Focus Neutron Yields with Fast Gas Jets

    NASA Astrophysics Data System (ADS)

    McMahon, Matthew; Kueny, Christopher; Stein, Elizabeth; Link, Anthony; Schmidt, Andrea

    2016-10-01

    We report a study using the particle-in-cell code LSP to perform fully kinetic simulations modeling dense plasma focus (DPF) devices with high density gas jets on axis. The high density jet models fast gas puffs which allow for more mass on axis while maintaining the optimal pressure for the DPF. As the density of the jet compared to the background fill increases we find the neutron yield increases, as does the variability in the neutron yield. Introducing perturbations in the jet density allow for consistent seeding of the m =0 instability leading to more consistent ion acceleration and higher neutron yields with less variability. Jets with higher on axis density are found to have the greatest yield. The optimal jet configuration is explored. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. Asymmetric frequency dependence of plasma jet formation in resonator electrode

    NASA Astrophysics Data System (ADS)

    Nam, Woo Jin; Lee, Seung Taek; Jeong, Seok Yong; Lee, Jae Koo; Yun, Gunsu S.

    2017-05-01

    Large aspect ratio plasma jets with sub-mm diameter are produced by a microwave coaxial resonator electrode. The jet length shows a sharp asymmetric dependence on the drive frequency: the plasma jet suddenly turns off below a critical frequency while the jet length slowly decreases above the frequency. A general mechanism is proposed to explain the asymmetry based on a universal feedback relation among the plasma impedance, the power coupling efficiency and the plasma dimension in resonator type electrodes. The input impedance of the resonator electrode changes depending on the plasma size formed in the electrode. The degree of the impedance mismatch between the electrode-plasma and the power source determines the power coupling efficiency and the resistive loss in the electrode which in turn affects the plasma size. The asymmetric dependence on the drive frequency is a consequence of the fact that the resonance frequency decreases for increasing plasma size. The feedback model shows a good agreement with the experimental measurements, providing essential information for the plasma control.

  17. Numerical Study on Plasma Jet and Particle Behavior in Multi-arc Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Öte, M.; Schein, J.; Zimmermann, S.

    2017-06-01

    Plasma jet and particle behavior in conventional single-arc plasma spraying has been subject to intensive numerical research. However, multi-arc plasma spraying is a different case which has yet to be investigated more closely. Numerical models developed to investigate the characteristics of multi-arc plasma spraying (plasma generator, plasma jet, and plasma-particle interaction models) were introduced in previous publications by the authors. The plasma generator and plasma jet models were already validated by comparing calculated plasma temperatures with results of emission spectroscopic computed tomography. In this study, the above-mentioned models were subjected to further validation effort. Calculated particle in-flight characteristics were compared with those determined by means of particle diagnostics and high-speed videography. The results show very good agreement. The main aim of the current publication is to derive conclusions regarding the general characteristics of plasma jet and particle in-flight behavior in multi-arc plasma spraying. For this purpose, a numerical parameter study is conducted in which the validated models are used to allow variations in the process parameters. Results regarding plasma jet/particle in-flight temperatures and velocities are presented. Furthermore, the general characteristics of plasma jet and particle behavior in multi-arc plasma spraying are discussed and explained. This contributes to better understanding of the multi-arc plasma spraying process, in particular regarding the injection behavior of particles into hot regions of the plasma jet. Finally, an example test case showing a possible practical application area of the models is introduced.

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

    SciTech Connect

    Shashurin, A.; Keidar, M.

    2015-12-15

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

  19. Cold atmospheric plasma jet in an axial DC electric field

    NASA Astrophysics Data System (ADS)

    Lin, Li; Keidar, Michael

    2016-08-01

    Cold atmospheric plasma (CAP) jet is currently intensively investigated as a tool for new and potentially transformative cancer treatment modality. However, there are still many unknowns about the jet behavior that requires attention. In this paper, a helium CAP jet is tested in an electrostatic field generated by a copper ring. Using Rayleigh microwave scattering method, some delays of the electron density peaks for different ring potentials are observed. Meanwhile, a similar phenomenon associated with the bullet velocity is found. Chemical species distribution along the jet is analyzed based on the jet optical emission spectra. The spectra indicate that a lower ring potential, i.e., lower DC background electric field, can increase the amount of excited N2, N2+, He, and O in the region before the ring, but can decrease the amount of excited NO and HO almost along the entire jet. Combining all the results above, we discovered that an extra DC potential mainly affects the temporal plasma jet properties. Also, it is possible to manipulate the chemical compositions of the jet using a ring with certain electric potentials.

  20. Cold atmospheric plasma jet in an axial DC electric field

    SciTech Connect

    Lin, Li E-mail: keidar@gwu.edu; Keidar, Michael E-mail: keidar@gwu.edu

    2016-08-15

    Cold atmospheric plasma (CAP) jet is currently intensively investigated as a tool for new and potentially transformative cancer treatment modality. However, there are still many unknowns about the jet behavior that requires attention. In this paper, a helium CAP jet is tested in an electrostatic field generated by a copper ring. Using Rayleigh microwave scattering method, some delays of the electron density peaks for different ring potentials are observed. Meanwhile, a similar phenomenon associated with the bullet velocity is found. Chemical species distribution along the jet is analyzed based on the jet optical emission spectra. The spectra indicate that a lower ring potential, i.e., lower DC background electric field, can increase the amount of excited N{sub 2}, N{sub 2}{sup +}, He, and O in the region before the ring, but can decrease the amount of excited NO and HO almost along the entire jet. Combining all the results above, we discovered that an extra DC potential mainly affects the temporal plasma jet properties. Also, it is possible to manipulate the chemical compositions of the jet using a ring with certain electric potentials.

  1. Charged-particle acceleration in braking plasma jets.

    PubMed

    Artemyev, A V

    2014-03-01

    In this paper we describe the mechanism of the charged particle acceleration in space plasma systems. We consider the interaction of nonrelativistic particles with a sub-Alfvenic plasma jet originated from the magnetic reconnection. The sharp front with increased magnetic field amplitude forms in the jet leading edge. Propagation of the jet in the inhomogeneous background plasma results in front braking. We show that particles can interact with this front in a resonance manner. Synchronization of particle reflections from the front and the front braking provides the stable trapping of particles in the vicinity of the front. This trapping supports the effective particle acceleration along the front. The mechanism of acceleration is potentially important due to the prevalence of the magnetic reconnection in space and astrophysical plasmas.

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

    SciTech Connect

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

    2010-05-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  4. Effect of a floating electrode on a plasma jet

    SciTech Connect

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

    2013-08-15

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

  5. Plasma performance in JET: Achievements and projections

    SciTech Connect

    Gibson, A.

    1988-01-01

    An account is given of recent experimental advances on JET, especially as they relate to fusion performance. Scaling relations are used to identify the critical parameters which need to be optimized to secure the best fusion performance. Finally the established best performance of JET is used as a base to project the performance to be expected in future D-T operation. 13 refs., 20 figs., 6 tabs.

  6. Dust generation at interaction of plasma jet with surfaces

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  7. Dynamics of apokamp-type atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Sosnin, Eduard A.; Panarin, Victor A.; Skakun, Victor S.; Baksht, Evgeny Kh.; Tarasenko, Victor F.

    2017-02-01

    The paper describes a new discharge source of atmospheric pressure plasma jets (APPJs) in air with no gas supply through the discharge region. In this discharge mode, plasma jets develop from the bending point of a bright current channel between two electrodes and are therefore termed an apokamp (from Greek `off' and `bend'). The apokamp can represent single plasma jets of length up 6 cm or several jets, and the temperature of such jets can range from more than 1000 °C at their base to 100-250 °C at their tip. Apokamps are formed at maximum applied voltage of positive polarity, provided that the second electrode is capacitively decoupled with ground. According to high-speed photography with time resolution from several nanoseconds to several tens of nanoseconds, the apokamp consists of a set of plasma bullets moving with a velocity of 100-220 km/s, which excludes the convective mechanism of plasma decay. Estimates on a 100-ns scale show that the near-electrode zones and the zones from which apokamps develop are close in temperature.

  8. Magnetohydrodynamic simulation study of plasma jets and plasma-surface contact in coaxial plasma accelerators

    NASA Astrophysics Data System (ADS)

    Subramaniam, Vivek; Raja, Laxminarayan L.

    2017-06-01

    Recent experiments by Loebner et al. [IEEE Trans. Plasma Sci. 44, 1534 (2016)] studied the effect of a hypervelocity jet emanating from a coaxial plasma accelerator incident on target surfaces in an effort to mimic the transient loading created during edge localized mode disruption events in fusion plasmas. In this paper, we present a magnetohydrodynamic (MHD) numerical model to simulate plasma jet formation and plasma-surface contact in this coaxial plasma accelerator experiment. The MHD system of equations is spatially discretized using a cell-centered finite volume formulation. The temporal discretization is performed using a fully implicit backward Euler scheme and the resultant stiff system of nonlinear equations is solved using the Newton method. The numerical model is employed to obtain some key insights into the physical processes responsible for the generation of extreme stagnation conditions on the target surfaces. Simulations of the plume (without the target plate) are performed to isolate and study phenomena such as the magnetic pinch effect that is responsible for launching pressure pulses into the jet free stream. The simulations also yield insights into the incipient conditions responsible for producing the pinch, such as the formation of conductive channels. The jet-target impact studies indicate the existence of two distinct stages involved in the plasma-surface interaction. A fast transient stage characterized by a thin normal shock transitions into a pseudo-steady stage that exhibits an extended oblique shock structure. A quadratic scaling of the pinch and stagnation conditions with the total current discharged between the electrodes is in qualitative agreement with the results obtained in the experiments. This also illustrates the dominant contribution of the magnetic pressure term in determining the magnitude of the quantities of interest.

  9. Magnetohydrodynamic simulation study of plasma jets and plasma-surface contact in coaxial plasma accelerators

    DOE PAGES

    Subramaniam, Vivek; Raja, Laxminarayan L.

    2017-06-13

    Recent experiments by Loebner et al. [IEEE Trans. Plasma Sci. 44, 1534 (2016)] studied the effect of a hypervelocity jet emanating from a coaxial plasma accelerator incident on target surfaces in an effort to mimic the transient loading created during edge localized mode disruption events in fusion plasmas. In this study, we present a magnetohydrodynamic (MHD) numerical model to simulate plasma jet formation and plasma-surface contact in this coaxial plasma accelerator experiment. The MHD system of equations is spatially discretized using a cell-centered finite volume formulation. The temporal discretization is performed using a fully implicit backward Euler scheme and themore » resultant stiff system of nonlinear equations is solved using the Newton method. The numerical model is employed to obtain some key insights into the physical processes responsible for the generation of extreme stagnation conditions on the target surfaces. Simulations of the plume (without the target plate) are performed to isolate and study phenomena such as the magnetic pinch effect that is responsible for launching pressure pulses into the jet free stream. The simulations also yield insights into the incipient conditions responsible for producing the pinch, such as the formation of conductive channels. The jet-target impact studies indicate the existence of two distinct stages involved in the plasma-surface interaction. A fast transient stage characterized by a thin normal shock transitions into a pseudo-steady stage that exhibits an extended oblique shock structure. A quadratic scaling of the pinch and stagnation conditions with the total current discharged between the electrodes is in qualitative agreement with the results obtained in the experiments. Finally, this also illustrates the dominant contribution of the magnetic pressure term in determining the magnitude of the quantities of interest.« less

  10. The effect of drainage configuration on heat transfer under an impinging liquid jet array

    SciTech Connect

    Garrett, K.; Webb, B.W.

    1999-11-01

    Impinging jets provide high transport coefficients which make them attractive for use in applications such as paper drying, quenching of metals, turbine blade cooling, and thermal control of a variety of high heat flux devices (electronics, X-ray optics, etc.). Here, the heat transfer characteristics of single and dual-exit drainage configurations for arrays of liquid jets impinging normal to a heated isoflux plate has been studied experimentally. The interaction of drainage channel crossflow from upstream jets and the stagnation jets and its impact on heat transfer was the focus of the investigation. Infrared thermography was used to measure the local temperature distribution on the heated plate, from which local heat transfer coefficients were determined. A single jet diameter was used, and jet arrays with jet-to-jet spacings of 4.8, 6, 9, and 12 jet diameters were studied. Average jet Reynolds numbers in the range 400--5,000 were investigated for jet nozzle-to-impingement plate spacings of 1, 2, and 4 jet diameters for fully flooded (submerged) drainage flow. A single jet-to-plate spacing large enough to yield free-surface jets was also studied. The data reveal a complex dependence of local and average Nusselt numbers on the geometric parameters which describe the problem configuration.

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

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

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

  12. Degradation of bromophenol blue molecule during argon plasma jet irradiation

    NASA Astrophysics Data System (ADS)

    Matinzadeh, Ziba; Shahgoli, Farhad; Abbasi, Hamed; Ghoranneviss, Mahmood; Salem, Mohammad Kazem

    2017-06-01

    The aim of this paper is to study degradation of a bromophenol blue molecule (C19H10Br4O5S) using direct irradiation of cold atmospheric argon plasma jet. The pH of the bromophenol blue solution has been measured as well as its absorbance spectra and conductivity before and after the irradiation of non-thermal plasma jet in various time durations. The results indicated that the lengths of conjugated systems in the molecular structure of bromophenol blue decreased, and that the bromophenol blue solution was decolorized as a result of the decomposition of bromophenol blue. This result shows that non-thermal plasma jet irradiation is capable of decomposing, and can also be used for water purification.

  13. Particle and gas velocity measurements in a dc plasma jet

    SciTech Connect

    Lesinski, J.; Mizera-Lesinska, B.; Jurewicz, J.; Boulos, M.I.

    1980-01-01

    Measurements were made, using Laser Doppler Anemometry (LDA), of the velocity of 53 ..mu..m alumina particles as they are injected in a dc plasma jet operated with an argon-nitrogen mixture (18.9 l/min argon and 4.7 l/min nitrogen) at a power level of 15.2 kW. Results obtained at distances between 5 and 150 mm from the nozzle showed the particles to penetrate the plasma jet and attain the gas velocity at about 50 mm from their point of injection. Plasma velocity measurements in the core region of the jet proved to be particularly difficult. Limitations of the LDA system with regard to its spatial resolution and seeding requirements are discussed.

  14. Schlieren Cinematography of Current Driven Plasma Jet Dynamics

    NASA Astrophysics Data System (ADS)

    Loebner, Keith; Underwood, Thomas; Cappelli, Mark

    2016-10-01

    Schlieren cinematography of a pulsed plasma deflagration jet is presented and analyzed. An ultra-high frame rate CMOS camera coupled to a Z-type laser Schlieren apparatus is used to obtain flow-field refractometry data for the continuous flow Z-pinch formed within the plasma deflagration jet. The 10 MHz frame rate for 256 consecutive frames provides high temporal resolution, enabling turbulent fluctuations and plasma instabilities to be visualized over the course of a single pulse (20 μs). The Schlieren signal is radiometrically calibrated to obtain a two dimensional mapping of the refraction angle of the axisymmetric pinch plasma, and this mapping is then Abel inverted to derive the plasma density distribution as a function radius, axial coordinate, and time. Analyses of previously unknown discharge characteristics and comparisons with prior work are discussed.

  15. Driving Flows in Laboratory Astrophysical Plasma Jets: The Mochi.LabJet Experiment

    NASA Astrophysics Data System (ADS)

    Carroll, Evan G.

    Mochi.Labjet is a new experiment at the University of Washington developed to investigate the interaction of shear flows in plasma jets with boundary conditions similar to an accretion disc system. This thesis details the engineering design and first plasmas of the Mochi.Labjet experiment. The experiment required construction of a new three electrode plasma gun with azimuthal symmetric gas injection, two optically-isolated pulsed power supplies for generating and sustaining plasma, and one optically-isolated pulsed power supply for generating a background magnetic field. Optical isolation is achieved with four custom circuits: the TTL-optical transmitter, optical-TTL receiver, optical-relay, and optical-tachometer circuits. First plasmas, during the commissioning phase of the apparatus, show evidence of flared jet structures with significant azimuthal symmetry.

  16. Counter-propagating plasma jet collision and shock formation on a compact current driver

    NASA Astrophysics Data System (ADS)

    Valenzuela, J. C.; Collins, G. W.; Zick, T.; Narkis, J.; Krasheninnikov, I.; Beg, F. N.

    2015-12-01

    In this paper we report on the ability of a compact current driver yielding 250 kA in 150 ns to produce counter-propagating plasma flows. The flows were produced by two vertically-opposed conical wire arrays separated by 1 cm, each comprised of 8 wires. With this array configuration, we were able to produce two supersonic plasma jets with velocities on the order of 100-200 km/s that propagate towards each other and collide. Aluminum wires were tested first; we observed a shock wave forming at the collision region that remained stationary for an extended period of time (∼50 ns) using optical probing diagnostics and Extreme Ultraviolet imaging. After this period, a bow shock is formed that propagates at 20 km/s towards the cathode of the array, likely due to small differences in the density and/or speed of the jets. The inter-jet ion mean free path was estimated to be larger than the shock scale length for aluminum, indicating that the shock is not mediated by collisions, but possibly by a magnetic field, whose potential sources are also discussed. Radiative cooling and density contrast between the jets were found to be important in the shock wave dynamics. We studied the importance of these effects by colliding jets of two different materials, using aluminum in one and copper in the other. In this configuration, the bow shock was observed to collapse into a thin shell and then to fragment, forming clumpy features. Simultaneously, the tip of the bow shock is seen to narrow as the bow shock moves at a similar speed observed in the Al-Al case. We discuss the similarity criteria for scaling astrophysical objects to the laboratory, finding that the dimensionless numbers are promising.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  18. Interaction between plasma synthetic jet and subsonic turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Zong, Haohua; Kotsonis, Marios

    2017-04-01

    This paper experimentally investigates the interaction between a plasma synthetic jet (PSJ) and a subsonic turbulent boundary layer (TBL) using a hotwire anemometer and phase-locked particle imaging velocimetry. The PSJ is interacting with a fully developed turbulent boundary layer developing on the flat wall of a square wind tunnel section of 1.7 m length. The Reynolds number based on the freestream velocity (U∞ = 20 m/s) and the boundary layer thickness (δ99 = 34.5 mm) at the location of interaction is 44 400. A large-volume (1696 mm3) three-electrode plasma synthetic jet actuator (PSJA) with a round exit orifice (D = 2 mm) is adopted to produce high-speed (92 m/s) and short-duration (Tjet = 1 ms) pulsed jets. The exit velocity variation of the adopted PSJA in a crossflow is shown to remain almost identical to that in quiescent conditions. However, the flow structures emanating from the interaction between the PSJ and the TBL are significantly different from what were observed in quiescent conditions. In the midspan xy plane (z = 0 mm), the erupted jet body initially follows a wall-normal trajectory accompanied by the formation of a distinctive front vortex ring. After three convective time scales the jet bends to the crossflow, thus limiting the peak penetration depth to approximately 0.58δ99. Comparison of the normalized jet trajectories indicates that the penetration ability of the PSJ is less than steady jets with the same momentum flow velocity. Prior to the jet diminishing, a recirculation region is observed in the leeward side of the jet body, experiencing first an expansion and then a contraction in the area. In the cross-stream yz plane, the signature structure of jets in a crossflow, the counter-rotating vortex pair (CVP), transports high-momentum flow from the outer layer to the near-wall region, leading to a fuller velocity profile and a drop in the boundary layer shape factor (1.3 to 1.2). In contrast to steady jets, the CVP produced by the PSJ

  19. Solar Array in Simulated LEO Plasma Environment

    NASA Technical Reports Server (NTRS)

    Vayner, Boris; Galofaro, Joel; Ferguson, Dale

    2004-01-01

    Six different types of solar arrays have been tested in large vacuum chambers. The low Earth orbit plasma environment was simulated in plasma vacuum chambers, where the parameters could be controlled precisely. Diagnostic equipment included spherical Langmuir probes, mass spectrometer, low-noise CCD camera with optical spectrometer, video camera, very sensitive current probe to measure arc current, and a voltage probe to register variations in a conductor potential. All data (except video) were obtained in digital form that allowed us to study the correlation between external parameters (plasma density, additional capacitance, bias voltage, etc) and arc characteristics (arc rate, arc current pulse width and amplitude, gas species partial pressures, and intensities of spectral lines). Arc inception voltages, arc rates, and current collections are measured for samples with different coverglass materials and thickness, interconnect designs, and cell sizes. It is shown that the array with wrapthrough interconnects have the highest arc threshold and the lowest current collection. Coverglass design with overhang results in decrease of current collection and increase of arc threshold. Doubling coverglass thickness causes the increase in arc inception voltage. Both arc inception voltage and current collection increase significantly with increasing a sample temperature to 80 C. Sustained discharges are initiated between adjacent cells with potential differences of 40 V for the sample with 300 m coverglass thickness and 60 V for the sample with 150 m coverglass thickness. Installation of cryogenic pump in large vacuum chamber provided the possibility of considerable outgassing of array surfaces which resulted in significant decrease of arc rate. Arc sites were determined by employing a video-camera, and it is shown that the most probable sites for arc inception are triple-junctions, even though some arcs were initiated in gaps between cells. It is also shown that the arc

  20. Solar Array in Simulated LEO Plasma Environment

    NASA Technical Reports Server (NTRS)

    Vayner, Boris; Galofaro, Joel; Ferguson, Dale

    2003-01-01

    Six different types of solar arrays have been tested in large vacuum chambers. The low earth orbit plasma environment was simulated in plasma vacuum chambers, where the parameters could be controlled precisely. Diagnostic equipment included spherical Langmuir probes, mass spectrometer, low-noise CCD camera with optical spectrometer, video camera, very sensitive current probe to measure arc current, and a voltage probe to register variations in a conductor potential. All data (except video) were obtained in digital form that allowed us to study the correlation between external parameters (plasma density, additional capacitance, bias voltage, etc) and arc characteristics (arc rate, arc current pulse width and amplitude, gas species partial pressures, and intensities of spectral lines). Arc inception voltages, arc rates, and current selections are measured for samples with different coverglass materials and thickness, interconnect designs, and cell sizes. It is shown that the array with wrapthrough interconnects have the highest arc threshold and the lowest current collection. Coverglass design with overhang results in decrease of current collection and increase of arc threshold. Doubling coverglass thickness cases the increase in arc inception voltage. Both arc inception voltage and current collection increase significantly with increasing a sample temperature to 80 C. Sustained discharges are initiated between adjacent cells with potential differences of 40 V for the sample with 300 micron coverglass thickness and 60 V for the sample with 150 micron coverglass thickness. Installation of cryogenic pump in large vacuum chamber provided the possibility of considerable outgassing of array surfaces which resulted in significant decrease of arc rate. Arc sites were determined by employing a video-camera, and it is shown that the most probable sites for arc inception are triple-junctions, even though some arcs were initiated in gaps between cells. It is also shown that the

  1. Cell array fabrication by plasma nanotexturing

    NASA Astrophysics Data System (ADS)

    Kontziampasis, Dimitrios; Bourkoula, Athanasia; Petrou, Panagiota; Tserepi, Angeliki; Kakabakos, Sotirios; Gogolides, Evangelos

    2013-05-01

    Cell behavior (i.e. attachment, proliferation, etc.) on nanostructured surfaces is currently a hot topic throughout the scientific community. However, studies often show diverging results due to differences in cells, local surface chemistry, and nanotopography fabrication methods. In this study, we use Oxygen plasma etching to both randomly nanotexture a PMMA surface and change its surface chemistry. We find that 3T3 cells behave quite differently on flat PMMA surfaces as compared to nanotextured ones, showing an on-off attachment behavior. Work is under progress to exploit this effect allowing selective cell capturing, and creation of cell arrays in adjacent plasma-nanotextured/smooth areas using a stencil mask during etching.

  2. Operation in the turbulent jet field of a linear array of multiple rectangular jets using a two-dimensional jet (Variation of mean velocity field)

    NASA Astrophysics Data System (ADS)

    Fujita, Shigetaka; Harima, Takashi

    2016-03-01

    The mean flowfield of a linear array of multiple rectangular jets run through transversely with a two-dimensional jet, has been investigated, experimentally. The object of this experiment is to operate both the velocity scale and the length scale of the multiple rectangular jets using a two-dimensional jet. The reason of the adoption of this nozzle exit shape was caused by the reports of authors in which the cruciform nozzle promoted the inward secondary flows strongly on both the two jet axes. Aspect ratio of the rectangular nozzle used in this experiment was 12.5. Reynolds number based on the nozzle width d and the exit mean velocity Ue (≅ 39 m / s) was kept constant 25000. Longitudinal mean velocity was measured using an X-array Hot-Wire Probe (lh = 3.1 μm in diameter, dh = 0.6 mm effective length : dh / lh = 194) operated by the linearized constant temperature anemometers (DANTEC), and the spanwise and the lateral mean velocities were measured using a yaw meter. The signals from the anemometers were passed through the low-pass filters and sampled using A.D. converter. The processing of the signals was made by a personal computer. Acquisition time of the signals was usually 60 seconds. From this experiment, it was revealed that the magnitude of the inward secondary flows on both the y and z axes in the upstream region of the present jet was promoted by a two-dimensional jet which run through transversely perpendicular to the multiple rectangular jets, therefore the potential core length on the x axis of the present jet extended 2.3 times longer than that of the multiple rectangular jets, and the half-velocity width on the rectangular jet axis of the present jet was suppressed 41% shorter compared with that of the multiple rectangular jets.

  3. Polymerization of acrylic acid using atmospheric pressure DBD plasma jet

    NASA Astrophysics Data System (ADS)

    Bashir, M.; Bashir, S.

    2016-08-01

    In this paper polymerization of acrylic acid was performed using non thermal atmospheric pressure plasma jet technology. The goal of this study is to deposit organic functional coatings for biomedical applications using a low cost and rapid growth rate plasma jet technique. The monomer solution of acrylic acid was vaporized and then fed into the argon plasma for coating. The discharge was powered using a laboratory made power supply operating with sinusoidal voltage signals at a frequency of 10 kHz. The optical emission spectra were collected in order to get insight into the plasma chemistry during deposition process. The coatings were characterized using Fourier transform infrared spectroscopy, atomic force microscopy and growth rates analysis. A high retention of carboxylic functional groups of the monomer was observed at the surface deposited using this low power technique.

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

    SciTech Connect

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

    2001-06-27

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

  5. Classifier based on support vector machine for JET plasma configurations

    SciTech Connect

    Dormido-Canto, S.; Farias, G.; Dormido, R.; Sanchez, J.; Duro, N.; Vargas, H.

    2008-10-15

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

  6. Discharge effects on gas flow dynamics in a plasma jet

    NASA Astrophysics Data System (ADS)

    Xian, Yu Bin; Hasnain Qaisrani, M.; Yue, Yuan Fu; Lu, Xin Pei

    2016-10-01

    Plasma is used as a flow visualization method to display the gas flow of a plasma jet. Using this method, it is found that a discharge in a plasma jet promotes the transition of the gas flow to turbulence. A discharge at intermediate frequency (˜6 kHz in this paper) has a stronger influence on the gas flow than that at lower or higher frequencies. Also, a higher discharge voltage enhances the transition of the gas flow to turbulence. Analysis reveals that pressure modulation induced both by the periodically directed movement of ionized helium and Ohmic heating on the gas flow plays an important role in inducing the transition of the helium flow regime. In addition, since the modulations induced by the high- and low-frequency discharges are determined by the frequency-selective effect, only intermediate-frequency (˜6 kHz) discharges effectively cause the helium flow transition from the laminar to the turbulent flow. Moreover, a discharge with a higher applied voltage makes a stronger impact on the helium flow because it generates stronger modulations. These conclusions are useful in designing cold plasma jets and plasma torches. Moreover, the relationship between the discharge parameters and the gas flow dynamics is a useful reference on active flow control with plasma actuators.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  9. Experimental tests for carbon nanomaterial synthesis using DC plasma jet

    NASA Astrophysics Data System (ADS)

    Lange, H.; Łabȩdź, O.; Tylska, I.; Huczko, A.; Bystrzejewski, M.

    2014-11-01

    In the frame of this work some experimental tests were performed in the plasma jet. Pure ethanol vapour alone or with the addition of fine iron powder were used to synthesize few-layer graphene or carbon-encapsulated iron nanoparticles, respectively.

  10. Degradation of tungsten under the action of a plasma jet

    NASA Astrophysics Data System (ADS)

    Voronin, A. V.; Sud'enkov, Yu. V.; Semenov, B. N.; Atroshenko, S. A.; Naumova, N. S.

    2014-07-01

    The degradation of the surface and structure of single-crystal tungsten and sintered powder tungsten during the action of a pulsed plasma jet is studied. It is shown that the degradation of a tungsten target during the action of a plasma jet with an energy flux density of 0.25-1 MJ/m2 is accompanied by surface evaporation and melting and the fracture of surface layers on scales of 150-250 μm. The results of a numerical simulation of the thermomechanical processes that occur in a tungsten target during the action of a plasma jet are presented. The degradation of tungsten during the action of a plasma jet is shown to proceed almost continuously from the action (evaporation, melting) to the times that are more than three orders of magnitude longer than the action time, which is caused by the thermomechanical processes occurring in the tungsten target. Moreover, the action of thermal stresses leads to structural and morphological changes throughout the sample volume, and these changes are accompanied by recrystallization in adiabatic shear bands.

  11. Plasma chamber testing of advanced photovoltaic solar array coupons

    NASA Astrophysics Data System (ADS)

    Hillard, G. Barry

    1994-05-01

    The solar array module plasma interactions experiment is a space shuttle experiment designed to investigate and quantify the high voltage plasma interactions. One of the objectives of the experiment is to test the performance of the Advanced Photovoltaic Solar Array (APSA). The material properties of array blanket are also studied as electric insulators for APSA arrays in high voltage conditions. Three twelve cell prototype coupons of silicon cells were constructed and tested in a space simulation chamber.

  12. Heat transfer characteristics within an array of impinging jets. Effects of crossflow temperature relative to jet temperature

    NASA Astrophysics Data System (ADS)

    Florschuetz, L. W.; Su, C. C.

    1985-10-01

    Spanwise average heat fluxes, resolved in the streamwise direction to one stream-wise hole spacing were measured for two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate. The jet flow, after impingement, was constrained to exit in a single direction along the channel formed by the jet orifice plate and heat transfer surface. The crossflow originated from the jets following impingement and an initial crossflow was present that approached the array through an upstream extension of the channel. The regional average heat fluxes are considered as a function of parameters associated with corresponding individual spanwise rows within the array. A linear superposition model was employed to formulate appropriate governing parameters for the individual row domain. The effects of flow history upstream of an individual row domain are also considered. The results are formulated in terms of individual spanwise row parameters. A corresponding set of streamwise resolved heat transfer characteristics formulated in terms of flow and geometric parameters characterizing the overall arrays is described.

  13. Heat transfer characteristics within an array of impinging jets. Effects of crossflow temperature relative to jet temperature

    NASA Technical Reports Server (NTRS)

    Florschuetz, L. W.; Su, C. C.

    1985-01-01

    Spanwise average heat fluxes, resolved in the streamwise direction to one stream-wise hole spacing were measured for two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate. The jet flow, after impingement, was constrained to exit in a single direction along the channel formed by the jet orifice plate and heat transfer surface. The crossflow originated from the jets following impingement and an initial crossflow was present that approached the array through an upstream extension of the channel. The regional average heat fluxes are considered as a function of parameters associated with corresponding individual spanwise rows within the array. A linear superposition model was employed to formulate appropriate governing parameters for the individual row domain. The effects of flow history upstream of an individual row domain are also considered. The results are formulated in terms of individual spanwise row parameters. A corresponding set of streamwise resolved heat transfer characteristics formulated in terms of flow and geometric parameters characterizing the overall arrays is described.

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

    NASA Astrophysics Data System (ADS)

    Ongena, Jef

    2012-07-01

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

  15. Interaction of radiatively cooled plasma jets with static gas and collimated supersonic gas jets

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    The MAGPIE generator (1.4 MA, 240 ns) drives an ablative plasma from a thin Al foil. The convergence of the plasma from the foil on its axis leads to the formation of a supersonic plasma jet, with a typical velocity of ~100 km/s. Jet-ambient interactions are studied either by injecting a highly-collimated, supersonic, cold gas jet above the foil using a nozzle, or by enclosing the foil inside a cell filled with neutral, static gas. In both cases, the plasma jet creates several shock features in the ambient medium. Experimental results from varied ambient parameters such as gas pressure and composition are presented together with 3-D MHD simulations. Work supported at AASC by DOE SBIR Grant DE-FG02-08ER85030, and at Imperial College by EPSRC Grant No. EP/G001324/1, by the NNSA under DOE Cooperative Agreements No. DE-F03-02NA00057 and No. DE-SC-0001063, and by a Marie Curie ERG grant.

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

    NASA Technical Reports Server (NTRS)

    Mayo, Robert M.

    1997-01-01

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

  17. Plasma jet acceleration of dust particles to hypervelocities

    SciTech Connect

    Ticos, C. M.; Wang, Zhehui; Wurden, G. A.; Kline, J. L.; Montgomery, D. S.

    2008-10-15

    A convenient method to accelerate simultaneously hundreds of micron-size dust particles to a few km/s over a distance of about 1 m is based on plasma drag. Plasma jets which can deliver sufficient momentum to the dust particles need to have speeds of at least several tens of km/s, densities of the order of 10{sup 22} m{sup -3} or higher, and low temperature {approx}1 eV, in order to prevent dust destruction. An experimental demonstration of dust particles acceleration to hypervelocities by plasma produced in a coaxial gun is presented here. The plasma flow speed is deduced from photodiode signals while the plasma density is measured by streaked spectroscopy. As a result of the interaction with the plasma jet, the dust grains are also heated to high temperatures and emit visible light. A hypervelocity dust shower is imaged in situ with a high speed video camera at some distance from the coaxial gun, where light emission from the plasma flow is less intense. The bright traces of the flying microparticles are used to infer their speed and acceleration by employing the time-of-flight technique. A simple model for plasma drag which accounts for ion collection on the grain surface gives predictions for dust accelerations which are in good agreement with the experimental observations.

  18. Dust particles interaction with plasma jet

    SciTech Connect

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

    2009-11-10

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

  19. Spectroscopic investigation of the plasma jet interaction with water

    NASA Astrophysics Data System (ADS)

    Almarashi, J. Q. M.; Alhazime, A. A.; Ellabban, M. A.; Mohamed, A.-A. H.

    2017-06-01

    In this paper, the emission spectra from plasma jet-water interaction is investigated. The plasma system consists of a quartz tube which is surrounded by two copper strips separated by 14 mm, the upper stripe is connected to AC high voltage power supply and the lower is grounded. A quartz-cuvette containing the water sample is placed at 13 mm down to the tube nozzle. Emission spectra from three regions; the distance between the two electrodes (A), the distance between the grounded electrode and the sample surface (B), and through the sample (C), are investigated. The results show clear differences between the spectra emitted from the three regions. Region A emits the highest intensities for the line spectra and argon 763 nm was the maximum. As well as, O radical emission spectra were detected with the highest intensities in region B. However, new bands and lines appear in the spectra from region C, due to interaction of the jet with water, depending on the water conditions and plasma operating parameters. These results declare that plasma jet interaction with water can be used as indicator for water quality and a detector for which species play the rule in plasma sterilization too.

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

    SciTech Connect

    Montani, Giovanni; Petitta, Jacopo

    2014-06-15

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

  1. Axial Plasma Jet Characterization on a Microsecond X-Pinch

    NASA Astrophysics Data System (ADS)

    Jaar, G. S.; Appartaim, R. K.

    2016-10-01

    The plasma jets generated from a two wire x-pinch have been studied with current quarter period of 1 μs. Wires of tungsten, aluminum, and titanium of 25-100 μm thicknesses have been exploded with a peak current value of 350kA. The plasma has been characterized using Nd:YAG based schlieren photography, time-resolved optical photography, x-ray photodiode detector, and a flat crystal x-ray spectrometer. The schlieren photographs enable determination of the evolution and velocity of the jets. Plasma temperature and density measurements at the crossing point will also be reported from the crystal spectrometer. This research is supported by the US DOE.

  2. Observation of Confined Current Ribbon in JET Plasmas

    SciTech Connect

    Solano, E. R.; Barrera, L.; Luna, E. de la; Lopez-Fraguas, A.; Lomas, P. J.; Alper, B.; Andrew, Y.; Arnoux, G.; Boboc, A.; Beurskens, M. N. A.; Brix, M.; Gerasimov, S.; Giroud, C.; Howell, D.; Korotkov, A.; Saarelma, S.; Sirinelli, A.; Pinches, S. D.; Zabeo, L.

    2010-05-07

    We report the identification of a localized current structure inside the JET plasma. It is a field-aligned closed helical ribbon, carrying current in the same direction as the background current profile (cocurrent), rotating toroidally with the ion velocity (corotating). It appears to be located at a flat spot in the plasma pressure profile, at the top of the pedestal. The structure appears spontaneously in low density, high rotation plasmas, and can last up to 1.4 s, a time comparable to a local resistive time. It considerably delays the appearance of the first edge localized mode.

  3. DAMAS Processing for a Phased Array Study in the NASA Langley Jet Noise Laboratory

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F.; Humphreys, William M.; Plassman, Gerald e.

    2010-01-01

    A jet noise measurement study was conducted using a phased microphone array system for a range of jet nozzle configurations and flow conditions. The test effort included convergent and convergent/divergent single flow nozzles, as well as conventional and chevron dual-flow core and fan configurations. Cold jets were tested with and without wind tunnel co-flow, whereas, hot jets were tested only with co-flow. The intent of the measurement effort was to allow evaluation of new phased array technologies for their ability to separate and quantify distributions of jet noise sources. In the present paper, the array post-processing method focused upon is DAMAS (Deconvolution Approach for the Mapping of Acoustic Sources) for the quantitative determination of spatial distributions of noise sources. Jet noise is highly complex with stationary and convecting noise sources, convecting flows that are the sources themselves, and shock-related and screech noise for supersonic flow. The analysis presented in this paper addresses some processing details with DAMAS, for the array positioned at 90 (normal) to the jet. The paper demonstrates the applicability of DAMAS and how it indicates when strong coherence is present. Also, a new approach to calibrating the array focus and position is introduced and demonstrated.

  4. Characterization of thermal and current quench of JET plasmas

    NASA Astrophysics Data System (ADS)

    Riccardo, V.; Barabaschi, P.; Loarte, A.; Sugihara, M.

    2004-11-01

    JET provides crucial scaling points and unique physics access for the extrapolation of disruptions to ITER. Disruption and ELM heat loads influence the selection of materials for plasma facing components (PFCs). Most JET thermal quenches occur when the plasma thermal energy is less than half that at full performance, suggesting a more optimistic life expectancy for ITER PFCs. The exceptions are ITB collapses and pure VDEs, which are also more likely to lead to the shortest thermal quenches. For the fast current quench disruptions, the EM load due to the induced eddy currents represent the most severe electromechanical design condition for in-vessel components. The minimum linear decay time normalised to the plasma cross section extrapolates to a 40 ms disruption for ITER, based on data from JET and most other tokamaks. Some very fast JET events are better fit by an exponential, with the minimum characteristic current decay time scaling to 35 ms for ITER. Contrary to expectations, the quench rate of high and low thermal energy disruptions does not vary substantially.

  5. Cold atmospheric pressure plasma jet interactions with plasmid DNA

    SciTech Connect

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

    2011-01-24

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

  6. Plasma jet printing for flexible substrates

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  7. Plasma jet printing for flexible substrates

    SciTech Connect

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

    2016-03-21

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

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

    NASA Astrophysics Data System (ADS)

    Lu, Xinpei

    2012-10-01

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

  9. Jet array impingement flow distributions and heat transfer characteristics: Effects of initial crossflow and nonuniform array geometry

    NASA Technical Reports Server (NTRS)

    Florschuetz, L. W.; Metzger, D. E.

    1982-01-01

    Flow distributions and heat transfer characteristics for two-dimensional arrays of circular air jets impinging on a surface parallel to the jet orifice plate were determined. The configurations considered were intended to model those of interest in current and contemplated gas turbine airfoil midchord cooling applications. The geometry of the airfoil applications considered dictates that all of the jet flow, after impingement, exit in the chordwise (i.e., streamwise) direction toward the trailing edge. Experimental results for the effect of an initial crossflow on both flow distributions and heat transfer characteristics for a number of the prior uniform array geometries. The effects of nonuniform array geometries on flow distributions and heat transfer characteristics for noninitial crossflow configurations are discussed.

  10. Effect of nonuniform geometries on flow distributions and heat transfer characteristics for arrays of impinging jets

    NASA Technical Reports Server (NTRS)

    Florschuetz, L. W.; Tseng, H. H.

    1984-01-01

    Two-dimensional arrays of circular jets impinging on a surface parallel to the jet orifice plate are considered. The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the impingement surface. Experimental results for the effects of streamwise nonuniform array geometries on streamwise flow distributions and heat transfer characteristics are presented. A flow distribution model for nonuniform arrays is developed and validated by comparison with the measured flow distributions. The model is then employed to compare nonuniform array streamwise resolved heat transfer coefficient data with previously reported uniform array data and with a previously developed correlation based on the uniform array data. It was found that uniform array results can, in general, serve as a satisfactory basis from which to predict heat transfer coefficients at individual spanwise rows of nonuniform arrays. However, significant differences were observed in some cases over the first one or two rows downstream of the geometric transition line of the nonuniform array.

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

    SciTech Connect

    Ticos, C. M.

    2010-12-14

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

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

    NASA Astrophysics Data System (ADS)

    Ticoş, C. M.

    2010-12-01

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

  13. Jet-Surface Interaction Test: Phased Array Noise Source Localization Results

    NASA Technical Reports Server (NTRS)

    Podboy, Gary G.

    2012-01-01

    An experiment was conducted to investigate the effect that a planar surface located near a jet flow has on the noise radiated to the far-field. Two different configurations were tested: 1) a shielding configuration in which the surface was located between the jet and the far-field microphones, and 2) a reflecting configuration in which the surface was mounted on the opposite side of the jet, and thus the jet noise was free to reflect off the surface toward the microphones. Both conventional far-field microphone and phased array noise source localization measurements were obtained. This paper discusses phased array results, while a companion paper discusses far-field results. The phased array data show that the axial distribution of noise sources in a jet can vary greatly depending on the jet operating condition and suggests that it would first be necessary to know or be able to predict this distribution in order to be able to predict the amount of noise reduction to expect from a given shielding configuration. The data obtained on both subsonic and supersonic jets show that the noise sources associated with a given frequency of noise tend to move downstream, and therefore, would become more difficult to shield, as jet Mach number increases. The noise source localization data obtained on cold, shock-containing jets suggests that the constructive interference of sound waves that produces noise at a given frequency within a broadband shock noise hump comes primarily from a small number of shocks, rather than from all the shocks at the same time. The reflecting configuration data illustrates that the law of reflection must be satisfied in order for jet noise to reflect off of a surface to an observer, and depending on the relative locations of the jet, the surface, and the observer, only some of the jet noise sources may satisfy this requirement.

  14. Multiple Pulses from Plasma Jets onto Liquid Covered Tissue

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    Atmospheric pressure plasma jets are being studied in the treatment of biological surfaces that are often covered by a thin layer of liquid. The plume of the plasma jet contains neutral radicals and charged species that solvate into the liquid and eventually form terminal species that reach the tissue below. The contribution of neutral and charged species to reactivity in the liquid is sensitive to whether the active plasma plume touches the liquid. In this paper, we discuss results from modeling the production of the aqueous species formed from the interaction of the plume of plasma jets over multiple pulses with the water layer, and the fluences of the species to the underlying tissue. The model used in this study, nonPDPSIM, solves transport equations for charged and neutral species and electron energy, Poisson's equation for the electric potential, and Navier-Stokes equations for the neutral gas flow. Radiation transport includes photoionization of O2 and H2O in the gas and liquid phases and photodissocation of H2Oaq in the liquid. Multiple pulses when the plasma plume touches and does not touch the liquid will be examined. Two regimes of hydrodynamics will be discussed - low repetition rates where the neutral radicals are blown away before the next discharge pulse, and high repetition rate when the plasma plume interacts with neutral radicals from previous pulses. The density of aqueous ions produced in the liquid layer is strongly dependent on whether the plasma effluent touches or does not touch the water surface. Work supported by DOE Office of Fusion Energy Science and NSF.

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

    PubMed Central

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

    2012-01-01

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

  16. Spectroscopic studies of the parameters of plasma jets during their propagation in the background plasma on the PF-3 facility

    NASA Astrophysics Data System (ADS)

    Dan’ko, S. A.; Ananyev, S. S.; Kalinin, Yu G.; Krauz, V. I.; Myalton, V. V.

    2017-04-01

    This paper presents measurement results of neon and helium plasma parameters in axial jets generated in plasma focus discharge. They were obtained in the course of experiments on laboratory modeling of astrophysical jets performed at the PF-3 facility. The plasma concentration was determined according to Stark broadening of spectral lines; the ionization temperature was determined by the average ion charge. The values of the concentration and temperature of jet plasma and background plasma at two distances from the pinch are also presented. In addition, an estimation was made of the heat content losses of the neon and helium jets during their movement through the surrounding medium.

  17. Stochastic particle acceleration by plasma waves in AGN jets

    SciTech Connect

    Li, Hui; Colgate, S.A.; Miller, J.A.

    1997-11-01

    The free energy stored in the stressed magnetic fields in AGN jets could be dissipated via generating turbulent plasma waves. The authors review several key wave-particle resonant interactions and point out the importance of a broad wave spectrum. Under several idealized assumptions, they show that the transit-time damping process can accelerate electrons to TeV energies in an AGN jet environment, and present a preliminary calculation on the evolution of plasma wave, electron, and photon distributions. The authors especially emphasize several open questions on particle acceleration by waves, and argue that a plausible scenario is to energize electrons out of the thermal background via transit-time damping and further accelerate them by the parallel propagating right-handed waves.

  18. Ion acceleration in multi-species cathodic plasma jet

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  19. Ion acceleration in multi-species cathodic plasma jet

    SciTech Connect

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

    2016-05-15

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

  20. Beryllium migration in JET ITER-like wall plasmas

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  1. Geometry optimization of linear and annular plasma synthetic jet actuators

    NASA Astrophysics Data System (ADS)

    Neretti, G.; Seri, P.; Taglioli, M.; Shaw, A.; Iza, F.; Borghi, C. A.

    2017-01-01

    The electrohydrodynamic (EHD) interaction induced in atmospheric air pressure by a surface dielectric barrier discharge (DBD) actuator has been experimentally investigated. Plasma synthetic jet actuators (PSJAs) are DBD actuators able to induce an air stream perpendicular to the actuator surface. These devices can be used in the field of aerodynamics to prevent or induce flow separation, modify the laminar to turbulent transition inside the boundary layer, and stabilize or mix air flows. They can also be used to enhance indirect plasma treatment effects, increasing the reactive species delivery rate onto surfaces and liquids. This can play a major role in plasma processing and chemical kinetics modelling, where often only diffusive mechanisms are considered. This paper reports on the importance that different electrode geometries can have on the performance of different PSJAs. A series of DBD aerodynamic actuators designed to produce perpendicular jets has been fabricated on two-layer printed circuit boards (PCBs). Both linear and annular geometries were considered, testing different upper electrode distances in the linear case and different diameters in the annular one. An AC voltage supplied at a peak of 11.5 kV and a frequency of 5 kHz was used. Lower electrodes were connected to the ground and buried in epoxy resin to avoid undesired plasma generation on the lower actuator surface. Voltage and current measurements were carried out to evaluate the active power delivered to the discharges. Schlieren imaging allowed the induced jets to be visualized and gave an estimate of their evolution and geometry. Pitot tube measurements were performed to obtain the velocity profiles of the PSJAs and to estimate the mechanical power delivered to the fluid. The optimal values of the inter-electrode distance and diameter were found in order to maximize jet velocity, mechanical power or efficiency. Annular geometries were found to achieve the best performance.

  2. Atmospheric Pressure Plasma Jet as an Accelerator of Tooth Bleaching

    PubMed Central

    Santak, Vedran; Zaplotnik, Rok; Milosevic, Slobodan; Klaric, Eva; Tarle, Zrinka

    2014-01-01

    Objective To study the effect of atmospheric pressure plasma (APP) jet as a potential accelerator of the degradation of hydrogen peroxide in bleaching gels which could lead to better and faster bleaching. Material and Methods 25 pastilles of hydroxylapatite were colored in green tea for 8 hours and were randomly divided into five groups (n = 5). The bleaching process was performed with 30% and 40% hydrogen peroxide (HP) gel alone and in conjunction with helium APP jet. During the bleaching treatment, optical emission spectroscopy and non-contact surface temperature measurement using pyrometer were performed. Color of the pastilles was determined by a red–green–blue (RGB) colorimeter. PH values of bleaching gels were measured before and after the plasma treatment on additional 10 pastilles using a pH meter with contact pH electrode. Results The color measurements of pastilles before and after the treatment showed that treatment with APP jet improved the bleaching effect by 32% and 15% in the case of 30% and 40% HP gel. Better results were obtained approximately six times faster than with a procedure suggested by the bleaching gel manufacturer. Optical emission spectroscopy proved that plasma has a chemically active role on the gel. After the APP treatment, pH values of bleaching gels dropped to about 50–75% of their initial value while the surface temperature increased by 8–10˚C above baseline. Conclusion The use of plasma jet provides more effective bleaching results in a shorter period of time without a significant temperature increase which may cause damage of the surrounding tissue. PMID:27688375

  3. Radiative Shocks And Plasma Jets As Laboratory Astrophysics Experiments

    SciTech Connect

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

    2007-08-02

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

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

    SciTech Connect

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

    2012-05-15

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

  5. Rapid surface treatment of polyamide 12 by microwave plasma jet

    NASA Astrophysics Data System (ADS)

    Hnilica, J.; Potočňáková, L.; Stupavská, M.; Kudrle, V.

    2014-01-01

    Polyamide 12 (PA 12) films were plasma treated using a microwave surface wave jet at atmospheric pressure. The parameters were the treatment time and the gas composition (argon or argon with admixtures). Moreover, the influence of power modulation was studied. It was found that significant change in wettability is achieved very rapidly, after only 25 ms of treatment. Plasma-induced surface changes are discussed using AFM, ATR-FTIR and XPS results. It is concluded that the increase in wettability is caused by both chemical and morphological changes.

  6. Atmospheric pressure plasma jet treatment of Salmonella Enteritidis inoculated eggshells.

    PubMed

    Moritz, Maike; Wiacek, Claudia; Koethe, Martin; Braun, Peggy G

    2017-03-20

    Contamination of eggshells with Salmonella Enteritidis remains a food safety concern. In many cases human salmonellosis within the EU can be traced back to raw or undercooked eggs and egg products. Atmospheric pressure plasma is a novel decontamination method that can reduce a wide range of pathogens. The aim of this work was to evaluate the possibility of using an effective short time cold plasma treatment to inactivate Salmonella Enteritidis on the eggshell. Therefore, artificially contaminated eggshells were treated with an atmospheric pressure plasma jet under different experimental settings with various exposure times (15-300s), distances from the plasma jet nozzle to the eggshell surface (5, 8 or 12mm), feed gas compositions (Ar, Ar with 0.2, 0.5 or 1.0% O2), gas flow rates (5 and 7slm) and different inoculations of Salmonella Enteritidis (10(1)-10(6)CFU/cm(2)). Atmospheric pressure plasma could reduce Salmonella Enteritidis on eggshells significantly. Reduction factors ranged between 0.22 and 2.27 log CFU (colony-forming units). Exposure time and, particularly at 10(4)CFU/cm(2) inoculation, feed gas had a major impact on Salmonella reduction. Precisely, longer exposure times led to higher reductions and Ar as feed gas was more effective than ArO2 mixtures.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  8. Radiation Yield and Dynamics of Planar Wire-Array Plasma

    SciTech Connect

    Kantsyrev, Victor; Safronova, Alla; Fedin, Dmitry; Ivanov, Vladimir; Esaulov, Andrey; Nalajala, Vidya; Shrestha, Ishor; Pokala, Shivaji; Ouart, Nicholas; Yilmaz, Fatih; Batie, Steven; Astanovitsky, Alexey; Laca, Paul; Le Galloudec, Bruno; Cowan, Thomas; Velikovich, Alexander; Chuvatin, Alexander; Gradel, Joshua

    2006-01-05

    In our experiments, we compared planar wire arrays, to which little energy could be coupled via the conventional magnetic-to-kinetic conversion mechanism, to cylindrical wire arrays of comparable dimensions and mass. The planar wire arrays were shown to radiate much higher peak power and more energy in sub-keV and keV spectral ranges, than cylindrical wire arrays. We tested the theoretical conjecture that enhanced resistivity due to the small-scale inhomogeneity of wire-array plasmas has a major effect on dynamics, energy coupling to and radiation performance of wire-array Z-pinches.

  9. Revealing plasma oscillation in THz spectrum from laser plasma of molecular jet.

    PubMed

    Li, Na; Bai, Ya; Miao, Tianshi; Liu, Peng; Li, Ruxin; Xu, Zhizhan

    2016-10-03

    Contribution of plasma oscillation to the broadband terahertz (THz) emission is revealed by interacting two-color (ω/2ω) laser pulses with a supersonic jet of nitrogen molecules. Temporal and spectral shifts of THz waves are observed as the plasma density varies. The former owes to the changing refractive index of the THz waves, and the latter correlates to the varying plasma frequency. Simulation of considering photocurrents, plasma oscillation and decaying plasma density explains the broadband THz spectrum and the varying THz spectrum. Plasma oscillation only contributes to THz waves at low plasma density owing to negligible plasma absorption. At the longer medium or higher density, the combining effects of plasma oscillation and absorption results in the observed low-frequency broadband THz spectra.

  10. Dynamics of Magnetized Plasma Jets and Bubbles Launched into a Background Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Wallace, B.; Zhang, Y.; Fisher, D. M.; Gilmore, M.

    2016-10-01

    The propagation of dense magnetized plasma, either collimated with mainly azimuthal B-field (jet) or toroidal with closed B-field (bubble), in a background plasma occurs in a number of solar and astrophysical cases. Such cases include coronal mass ejections moving in the background solar wind and extragalactic radio lobes expanding into the extragalactic medium. Understanding the detailed MHD behavior is crucial for correctly modeling these events. In order to further the understanding of such systems, we are investigating the injection of dense magnetized jets and bubbles into a lower density background magnetized plasma using a coaxial plasma gun and a background helicon or cathode plasma. In both jet and bubble cases, the MHD dynamics are found to be very different when launched into background plasma or magnetic field, as compared to vacuum. In the jet case, it is found that the inherent kink instability is stabilized by velocity shear developed due to added magnetic tension from the background field. In the bubble case, rather than directly relaxing to a minimum energy Taylor state (spheromak) as in vacuum, there is an expansion asymmetry and the bubble becomes Rayleigh-Taylor unstable on one side. Recent results will be presented. Work supported by the Army Research Office Award No. W911NF1510480.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  12. Effect of nozzle geometry on impingement heat transfer distribution from jet arrays

    SciTech Connect

    Owens, R.D.; Liburdy, J.A.

    1995-12-31

    Heat transfer distributions were determined for flat surfaces using three different 3 x 3 jet-impingement arrays. Each array used a different jet orifice cross sectional geometry, either circles, triangles, or ellipses. For each geometry, the jet-to-jet spacing divided by the hydraulic diameter, was three. Five flow rates were tested with Reynolds numbers ranging from 268 to 1,557. For each flow rate, the four jet array height-to-jet spacings (H/D) of 2, 3, 4, and 5 were tested. All of the parameters presented, such as the Reynolds and Nusselt numbers, were based on the orifice hydraulic diameter. In order to determine the heat transfer distributions for each condition tested, thermochromic liquid crystals were used as part of a transient heating testing method. In the majority of the tests, the ellipse array performed the best, with the triangular orifice close behind. Also, of the three orifice geometries, the ellipse had the lowest pressure drop. The heat transfer improvement was especially predominant at low Reynolds numbers.

  13. Study of atmospheric pressure plasma jet parameters generated by DC voltage driven cold plasma source

    NASA Astrophysics Data System (ADS)

    Wang, Xingxing; Shashurin, Alexey

    2017-08-01

    In this work, plasma and discharge parameters of a DC voltage driven cold plasma source were measured. The device exhibits a plasma jet with a length of 3 cm and a pulsation frequency of about 2.75 kHz. The peak current of each pulse was about 1.1 mA, and the duration was about 5 μs. The repetition rate could be increased by raising the DC voltage level. By utilizing the microwave scattering system, electron density in the plasma was measured to be about ˜1011 cm-3. Vibrational and rotational temperatures of atmospheric pressure plasma jets were also measured by optical emission spectroscopy. The vibrational temperature was measured to be 2850 K and rotational temperature to be 300 K at the applied voltage of 5 kV. No strong dependence of the temperatures was found with the DC voltage level.

  14. Z-pinch Plasma Temperature and Implosion Velocity from Laboratory Plasma Jets using Thomson Scattering

    NASA Astrophysics Data System (ADS)

    Banasek, Jacob; Byvank, Tom; Kusse, Bruce; Hammer, David

    2016-10-01

    We discuss the use of collective Thomson scattering to determine the implosion velocity and other properties of laboratory plasma jets. The plasma jet is created using a 1 MA pulsed power machine with a 15 μm Al radial foil load. The Thomson scattering laser has a maximum energy of 10 J at 526.5 nm with a pulse duration of 3 ns. Using a time gated ICCD camera and spectrometer system we are able to record the scattered spectrum from 9 or 18 regions along the laser path with sub-mm spatial resolution. Collecting scattered radiation from the same area at two different angles simultaneously enables determination of both the radial and azimuthal velocities. The scattered spectrum for non-magnetized jets indicates a radial implosion velocity of 27 km/s into the jets. A determination of ion and electron temperatures from the scattered spectrum is in progress. Comparing results using a laser energy of 10 J and 1 J shows noticeable effects on plasma jet properties when using 10 J. Therefore the lower laser energy must be used to determine the plasma properties. This research is supported by the NNSA Stewardship Sciences Academic Programs under DOE Cooperative Agreement DE-NA0001836.

  15. Influence of elliptical structure on impinging-jet-array heat transfer performances

    NASA Astrophysics Data System (ADS)

    Arjocu, Simona C.; Liburdy, James A.

    1997-11-01

    A three-by-three square array of submerged, elliptic, impinging jets in water was used to study the heat transfer distribution in the cooling process of a constant heat flux surface. Tow jet aspect ratios were used, 2 and 3, both with the same hydraulic diameter. The array was tested at Reynolds numbers from 300 to 1500 and impinging distances of 1 to 5 hydraulic diameters. Thermochromic liquid crystals wee used to map the local heat transfer coefficient using a transient method, while the jet temperature was kept constant. The liquid crystal images were recorded through an optical fiber coupled with a CCD camera and a frame grabber and analyzed based on an RGB-temperature calibration technique. The results are reported relative to the unit cell that is used to delimitate the central jet. The heat transfer variation is shown to depend on the impingement distance and Reynolds number. The elliptic jets exhibit axis switching, jet column instability and jet swaying. All of these mechanisms affect the enhancement of the heat transfer rate and its distribution. The results are compared in terms of average and local heat transfer coefficients, for both major and minor planes for the two jet aspect ratios.

  16. Impact of the Hall effect on high-energy-density plasma jets.

    PubMed

    Gourdain, P-A; Seyler, C E

    2013-01-04

    Using a 1-MA, 100 ns-rise-time pulsed power generator, radial foil configurations can produce strongly collimated plasma jets. The resulting jets have electron densities on the order of 10(20) cm(-3), temperatures above 50 eV and plasma velocities on the order of 100 km/s, giving Reynolds numbers of the order of 10(3), magnetic Reynolds and Péclet numbers on the order of 1. While Hall physics does not dominate jet dynamics due to the large particle density and flow inside, it strongly impacts flows in the jet periphery where plasma density is low. As a result, Hall physics affects indirectly the geometrical shape of the jet and its density profile. The comparison between experiments and numerical simulations demonstrates that the Hall term enhances the jet density when the plasma current flows away from the jet compared to the case where the plasma current flows towards it.

  17. Diamagnetic effect produced by the Fluxus-1 and -2 artificial plasma jet

    NASA Astrophysics Data System (ADS)

    Gavrilov, B. G.; Podgorny, A. I.; Podgorny, I. M.; Sobyanin, D. B.; Zetzer, J. I.; Erlandson, R. E.; Meng, C.-I.; Stoyanov, B. J.

    The purpose of the Fluxus-1 and -2 active experiments is to study plasma jets injected parallel to the magnetic field and to study the interaction of these jets with the magnetic field. The experiments were conducted using a shaped-charge device, known as an explosive type generator (ETG), that produced an artificial aluminum plasma jet. In Fluxus-1 and -2 the jet was injected nearly parallel to the geomagnetic field at an altitude of 140 km toward an instrumented diagnostic payload located about 100 m away from the ETG. A ∼50% reduction in the magnetic field was observed as the plasma jet passed by the diagnostic payload. Comparisons of 3-dimensional simulation results with the observed magnetic field perturbations suggest that the Fluxus-1 plasma jet was ∼30° from the magnetic field direction while the Fluxus-2 plasma jet was directed nearly parallel to the magnetic field.

  18. Adiabatic cooling of the artificial Porcupine plasma jet

    NASA Astrophysics Data System (ADS)

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

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  20. Interaction of steady jets with an array of permeable screens

    NASA Astrophysics Data System (ADS)

    Musta, Mustafa N.; Krueger, Paul S.

    2015-03-01

    Turbulent flows in porous media have important practical applications such as enhanced mixing of fuel and air, food drying, and cooling of electronics. However, experimental studies of turbulence in porous media are sparse due to the difficulties of measuring the complex flow environment. To this end, the interactions of steady jets with a porous medium formed from several parallel, transparent, permeable screens are studied using digital particle image velocimetry in a refractive indexed-matched environment. The permeable screens had porosities (open area ratios, ϕ) of 83.8, 69.0, 55.7, and 49.5 % and were held by a transparent frame that allowed the screen spacing to be changed. The steady jet results for Reynolds number ( Re), which is defined based on the jet exit velocity and jet diameter, of 1000 showed laminar, predominantly steady flow that was segregated inside the porous medium, but for Re ≥ 2000, the flow was unsteady and turbulent with a mean velocity field that was relatively smooth inside the porous medium. As a result, more traditional jet features of self-similarity and increasing jet width were compared for the Re ≥ 2000 results. Decreasing the porosity was observed to increase the width of the jet significantly, especially for low porosity screens, and slowed the jet flow speed. Some of the typical features for axisymmetric jets were observed, even though the flow impinged on the permeable screens. In particular, self-similarity (or near self-similar behavior) was observed for the cross-sectional mean velocity profiles and for turbulence quantities for porosities larger than 55.7 % inside the porous medium. The effect of ϕ on turbulence quantities was significant for Re ≥ 2000. Although turbulence intensity increased on the downstream side of the first screen, the high dissipation forced drastic decrease of turbulence levels further downstream in the porous domain. Finally, the screens increased the removal of momentum from the jet as

  1. Formation of a supersonic laser-driven plasma jet in a cylindrical channel

    NASA Astrophysics Data System (ADS)

    Badziak, J.; Pisarczyk, T.; Chodukowski, T.; Kasperczuk, A.; Parys, P.; Rosiński, M.; Wołowski, J.; Krousky, E.; Krasa, J.; Mašek, K.; Pfeifer, M.; Skala, J.; Ullschmied, J.; Velyhan, A.; Dhareshwar, L. J.; Gupta, N. K.; Rhee, Yong-Joo; Torrisi, L.; Pisarczyk, P.

    2009-11-01

    A simple method of supersonic plasma jet production where the jet is formed in a cylindrical channel guiding the plasma generated from a laser-irradiated thin foil target is proposed and examined. High-Mach number (≥10) plasma jets of parameters relevant to laboratory astrophysics applications using 120 J, 1.315 μm, and 0.3 ns laser pulse for a thin CH foil irradiation are demonstrated. The method seems to be flexible in the production of jets of various compositions and hydrodynamic parameters and does not require high-energy lasers for the jet generation.

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

    SciTech Connect

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

    2010-07-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  4. 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)

  5. Thermal-hydraulic performance of convective boiling jet array impingement

    NASA Astrophysics Data System (ADS)

    Jenkins, R.; De Brún, C.; Kempers, R.; Lupoi, R.; Robinson, A. J.

    2016-09-01

    Jet impingement boiling is investigated with regard to heat transfer and pressure drop performance using a novel laser sintered 3D printed jet impingement manifold design. Water was the working fluid at atmospheric pressure with inlet subcooling of 7oC. The convective boiling performance of the impinging jet system was investigated for a flat copper target surface for 2700≤Re≤5400. The results indicate that the heat transfer performance of the impinging jet is independent of Reynolds number for fully developed boiling. Also, the investigation of nozzle to plate spacing shows that low spacing delays the onset of nucleate boiling causing a superheat overshoot that is not observed with larger gaps. However, no sensitivity to the gap spacing was measured once boiling was fully developed. The assessment of the pressure drop performance showed that the design effectively transfers heat with low pumping power requirements. In particular, owing to the insensitivity of the heat transfer to flow rate during fully developed boiling, the coefficient of performance of jet impingement boiling in the fully developed boiling regime deteriorates with increased flow rate due to the increase in pumping power flux.

  6. Plasma Jet Braking: Energy Dissipation and Nonadiabatic Electrons

    SciTech Connect

    Khotyaintsev, Yu. V.; Cully, C. M.; Vaivads, A.; Andre, M.; Owen, C. J.

    2011-04-22

    We report in situ observations by the Cluster spacecraft of wave-particle interactions in a magnetic flux pileup region created by a magnetic reconnection outflow jet in Earth's magnetotail. Two distinct regions of wave activity are identified: lower-hybrid drift waves at the front edge and whistler-mode waves inside the pileup region. The whistler-mode waves are locally generated by the electron temperature anisotropy, and provide evidence for ongoing betatron energization caused by magnetic flux pileup. The whistler-mode waves cause fast pitch-angle scattering of electrons and isotropization of the electron distribution, thus making the flow braking process nonadiabatic. The waves strongly affect the electron dynamics and thus play an important role in the energy conversion chain during plasma jet braking.

  7. Pulsating jet-like structures in magnetized plasma

    SciTech Connect

    Goncharov, V. P.; Pavlov, V. I.

    2016-08-15

    The formation of pulsating jet-like structures has been studied in the scope of the nonhydrostatic model of a magnetized plasma with horizontally nonuniform density. We discuss two mechanisms which are capable of stopping the gravitational spreading appearing to grace the Rayleigh-Taylor instability and to lead to the formation of stationary or oscillating localized structures. One of them is caused by the Coriolis effect in the rotating frames, and another is connected with the Lorentz effect for magnetized fluids. Magnetized jets/drops with a positive buoyancy must oscillate in transversal size and can manifest themselves as “radio pulsars.” The estimates of their frequencies are made for conditions typical for the neutron star's ocean.

  8. Plasma Jet Braking: Energy Dissipation and Nonadiabatic Electrons

    NASA Astrophysics Data System (ADS)

    Khotyaintsev, Yu. V.; Cully, C. M.; Vaivads, A.; André, M.; Owen, C. J.

    2011-04-01

    We report in situ observations by the Cluster spacecraft of wave-particle interactions in a magnetic flux pileup region created by a magnetic reconnection outflow jet in Earth’s magnetotail. Two distinct regions of wave activity are identified: lower-hybrid drift waves at the front edge and whistler-mode waves inside the pileup region. The whistler-mode waves are locally generated by the electron temperature anisotropy, and provide evidence for ongoing betatron energization caused by magnetic flux pileup. The whistler-mode waves cause fast pitch-angle scattering of electrons and isotropization of the electron distribution, thus making the flow braking process nonadiabatic. The waves strongly affect the electron dynamics and thus play an important role in the energy conversion chain during plasma jet braking.

  9. Plasma jet braking: energy dissipation and nonadiabatic electrons.

    PubMed

    Khotyaintsev, Yu V; Cully, C M; Vaivads, A; André, M; Owen, C J

    2011-04-22

    We report in situ observations by the Cluster spacecraft of wave-particle interactions in a magnetic flux pileup region created by a magnetic reconnection outflow jet in Earth's magnetotail. Two distinct regions of wave activity are identified: lower-hybrid drift waves at the front edge and whistler-mode waves inside the pileup region. The whistler-mode waves are locally generated by the electron temperature anisotropy, and provide evidence for ongoing betatron energization caused by magnetic flux pileup. The whistler-mode waves cause fast pitch-angle scattering of electrons and isotropization of the electron distribution, thus making the flow braking process nonadiabatic. The waves strongly affect the electron dynamics and thus play an important role in the energy conversion chain during plasma jet braking.

  10. Pulsating jet-like structures in magnetized plasma

    NASA Astrophysics Data System (ADS)

    Goncharov, V. P.; Pavlov, V. I.

    2016-08-01

    The formation of pulsating jet-like structures has been studied in the scope of the nonhydrostatic model of a magnetized plasma with horizontally nonuniform density. We discuss two mechanisms which are capable of stopping the gravitational spreading appearing to grace the Rayleigh-Taylor instability and to lead to the formation of stationary or oscillating localized structures. One of them is caused by the Coriolis effect in the rotating frames, and another is connected with the Lorentz effect for magnetized fluids. Magnetized jets/drops with a positive buoyancy must oscillate in transversal size and can manifest themselves as "radio pulsars." The estimates of their frequencies are made for conditions typical for the neutron star's ocean.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  12. Impingement flow heat transfer measurements of turbine blades using a jet array

    NASA Astrophysics Data System (ADS)

    Vantreuren, Kenneth W.

    1994-08-01

    The requirement for increased gas turbine engine performance has led to the use of much higher turbine entry temperature (TET). The higher temperatures require active cooling of the turbine blade using compressor bleed air. Arrays of impinging jets are one method currently used to reduce the blade temperature on the midspan and leading edge. Air flows through small holes in a blade insert and is directed on the inside surface of a turbine blade to reduce local surface temperature. The engine situation was represented by a 10-20 times scale model tested in the internal cooling transient facility at the University of Oxford. The geometry chosen was for a widely spaced array with a jet spacing of 8d and a plate thickness to jet diameter of 1.2. Experiments were accomplished for a range of impingement plate to target surface spacings, z/d, (1, 2 and 4) and jet Reynolds numbers, Re(sub j), (10,000 - 40,000) with both staggered and inline array hole configurations. The transient liquid crystal technique, both peak intensity narrowband and hue temperature history wideband, enabled the determination of heat transfer coefficient and adiabatic wall temperature. For the first time, local detail of heat transfer on the target surface as well as observation of the crossflow influence on the jet at the target surface are possible. A large variation in heat transfer exists between the stagnation point and channel passage between jets (2-4 times) which was unknown in previous experiments.

  13. Flow instabilities in non-uniformly heated helium jet arrays used for divertor PFCs

    SciTech Connect

    Youchison, Dennis L.

    2015-07-30

    In this study, due to a lack of prototypical experimental data, little is known about the off-normal behavior of recently proposed divertor jet cooling concepts. This article describes a computational fluid dynamics (CFD) study on two jet array designs to investigate their susceptibility to parallel flow instabilities induced by non-uniform heating and large increases in the helium outlet temperature. The study compared a single 25-jet helium-cooled modular divertor (HEMJ) thimble and a micro-jet array with 116 jets. Both have pure tungsten armor and a total mass flow rate of 10 g/s at a 600 °C inlet temperature. We investigated flow perturbations caused by a 30 MW/m2 off-normal heat flux applied over a 25 mm2 area in addition to the nominal 5 MW/m2 applied over a 75 mm2 portion of the face. The micro-jet array exhibited lower temperatures and a more uniform surface temperature distribution than the HEMJ thimble. We also investigated the response of a manifolded nine-finger HEMJ assembly using the nominal heat flux and a 274 mm2 heated area. For the 30 MW/m2 case, the micro-jet array absorbed 750 W in the helium with a maximum armor surface temperature of 1280 °C and a fluid/solid interface temperature of 801 °C. The HEMJ absorbed 750 W with a maximum armor surface temperature of 1411 °C and a fluid/solid interface temperature of 844 °C. For comparison, both the single HEMJ finger and the micro-jet array used 5-mm-thick tungsten armor. The ratio of maximum to average temperature and variations in the local heat transfer coefficient were lower for the micro-jet array compared to the HEMJ device. Although high heat flux testing is required to validate the results obtained in these simulations, the results provide important guidance in jet design and manifolding to increase heat removal while providing more even temperature distribution and minimizing non-uniformity in the gas flow and thermal stresses at the

  14. Flow instabilities in non-uniformly heated helium jet arrays used for divertor PFCs

    DOE PAGES

    Youchison, Dennis L.

    2015-07-30

    In this study, due to a lack of prototypical experimental data, little is known about the off-normal behavior of recently proposed divertor jet cooling concepts. This article describes a computational fluid dynamics (CFD) study on two jet array designs to investigate their susceptibility to parallel flow instabilities induced by non-uniform heating and large increases in the helium outlet temperature. The study compared a single 25-jet helium-cooled modular divertor (HEMJ) thimble and a micro-jet array with 116 jets. Both have pure tungsten armor and a total mass flow rate of 10 g/s at a 600 °C inlet temperature. We investigated flowmore » perturbations caused by a 30 MW/m2 off-normal heat flux applied over a 25 mm2 area in addition to the nominal 5 MW/m2 applied over a 75 mm2 portion of the face. The micro-jet array exhibited lower temperatures and a more uniform surface temperature distribution than the HEMJ thimble. We also investigated the response of a manifolded nine-finger HEMJ assembly using the nominal heat flux and a 274 mm2 heated area. For the 30 MW/m2 case, the micro-jet array absorbed 750 W in the helium with a maximum armor surface temperature of 1280 °C and a fluid/solid interface temperature of 801 °C. The HEMJ absorbed 750 W with a maximum armor surface temperature of 1411 °C and a fluid/solid interface temperature of 844 °C. For comparison, both the single HEMJ finger and the micro-jet array used 5-mm-thick tungsten armor. The ratio of maximum to average temperature and variations in the local heat transfer coefficient were lower for the micro-jet array compared to the HEMJ device. Although high heat flux testing is required to validate the results obtained in these simulations, the results provide important guidance in jet design and manifolding to increase heat removal while providing more even temperature distribution and minimizing non-uniformity in the gas flow and thermal stresses at the armor joint.« less

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

    SciTech Connect

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

    2013-02-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  17. Astrophysical Jets with Conical Wire Arrays: Radiative Cooling, Rotation and Deflection

    SciTech Connect

    Ampleford, D. J.; Jennings, C. A.; Lebedev, S. V.; Bland, S. N.; Hall, G. N.; Suzuki-Vidal, F.; Palmer, J. B. A.; Chittenden, J. P.; Ciardi, A.; Bott, S. C.

    2009-01-21

    Highly collimated outflows or jets are produced by a number of astrophysical objects including protostars. The morphology and collimation of these jets is thought to be strongly influenced by the effects of radiative cooling, angular momentum and the interstellar medium surrounding the jet. Astrophysically relevant experiments are performed with conical wire array z-pinches investigating each of these effects. It is possible in each case to enter the appropriate parameter regime, leading the way towards future experiments where these different techniques can be more fully combined.

  18. Refractory graphite skimmers for supersonic free-jet, supersonic arc-jet, and plasma discharge applications

    NASA Astrophysics Data System (ADS)

    Jordan, D. C.; Barling, R.; Doak, R. B.

    1999-03-01

    The fabrication of molecular beam "skimmers" from electrical discharge machining (EDM) graphite is reported. EDM graphite is highly refractory and is easily machined using conventional cutting and grinding techniques. In its most fine-grained form, EDM graphite can be machined free-standing to a knife-edge lip radius of ˜1 μm, providing excellent skimmer aerodynamics. Being refractory, such EDM skimmers are of particular interest in sampling or collimating high-temperature plasma discharges. Our explicit application is in skimming an electrical discharge supersonic free-jet of molecular nitrogen, forming a molecular beam of A 3Σu+ metastable N2 to be used in the heteroepitaxial growth of III-N wide-band-gap semiconductors. In view of the their economy, ease of manufacture, and excellent aerodynamics, the skimmers may also find use in skimming conventional, nondischarge supersonic free-jets. The performance of the EDM skimmers was tested in a conventional helium supersonic free-jet expansion, measuring the time-of-flight distribution and beam intensity as a function of nozzle pressure and nozzle-skimmer separation. Direct comparison with commercial nickel and copper skimmers showed the EDM graphite skimmers to perform nearly as well as the best commercial metal skimmers. The refractory properties of the skimmers were tested in a high-temperature arc-discharge supersonic free-jet expansion of 10% nitrogen in argon. Exposure to a plasma plume of ˜7500 K for over 6 h produced only relatively minor deterioration of the EDM graphite skimmer.

  19. Jet-Surface Interaction Test: Phased Array Noise Source Localization Results

    NASA Technical Reports Server (NTRS)

    Podboy, Gary

    2012-01-01

    Subsonic jets are relatively simple. The peak noise source location gradually moves upstream toward the nozzle as frequency increases. 2) Supersonic jets are more complicated. The peak noise source location moves downstream as frequency increases through a BBSN hump. 3) In both subsonic and supersonic jets the peak noise source location corresponding to a given frequency of noise moves downstream as jet Mach number increases. 4) The noise generated at a given frequency in a BBSN hump is generated by a small number of shocks, not from all the shocks at the same time. 5) Single microphone spectrum levels decrease when the noise source locations measured with the phased array are blocked by a shielding surface. This consistency validates the phased array data and the stationary monopole source model used to process it. 6) Reflecting surface data illustrate that the law of reflection must be satisfied for noise to reflect off a surface toward an observer. Depending on the relative locations of the jet, the surface and the observer only some of the jet noise sources may satisfy this requirement. 7) The low frequency noise created when a jet flow impinges on a surface comes primarily from the trailing edge regardless of the axial extent impacted by the flow.

  20. Nonthermal atmospheric argon plasma jet effects on Escherichia coli biomacromolecules.

    PubMed

    Hosseinzadeh Colagar, Abasalt; Memariani, Hamed; Sohbatzadeh, Farshad; Valinataj Omran, Azadeh

    2013-12-01

    Nonthermal atmospheric plasma jet, a promising technology based on ionized gas at low temperatures, can be applied for disinfection of contaminated surfaces. In this study, Escherichia coli cells and their macromolecules were exposed to the nonthermal atmospheric argon plasma jet for different time durations. Total protein, genomic DNA, and malondialdehyde (MDA) levels of E. coli were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining; agarose gel electrophoresis; and measurement of absorbance at 534 nm, respectively. After exposure, the spectroscopic results of liquid samples indicated that the survival reduction of E. coli can reach to 100 % in an exposure time of 600 s. Moreover, inactivation zones of E. coli, DNA degradation, and MDA levels were significantly increased. Additionally, banding patterns of total protein were changed and amino acid concentrations increased following ninhydrin test. The experimental results suggest that the nonthermal plasma could serve as an effective instrument for both sterilizing E. coli and degrading macromolecules from the surface of the objects being sterilized.

  1. Jet-Surface Interaction Test: Phased Array Noise Source Localization Results

    NASA Technical Reports Server (NTRS)

    Podboy, Gary G.

    2013-01-01

    An experiment was conducted to investigate the effect that a planar surface located near a jet flow has on the noise radiated to the far-field. Two different configurations were tested: 1) a shielding configuration in which the surface was located between the jet and the far-field microphones, and 2) a reflecting configuration in which the surface was mounted on the opposite side of the jet, and thus the jet noise was free to reflect off the surface toward the microphones. Both conventional far-field microphone and phased array noise source localization measurements were obtained. This paper discusses phased array results, while a companion paper (Brown, C.A., "Jet-Surface Interaction Test: Far-Field Noise Results," ASME paper GT2012-69639, June 2012.) discusses far-field results. The phased array data show that the axial distribution of noise sources in a jet can vary greatly depending on the jet operating condition and suggests that it would first be necessary to know or be able to predict this distribution in order to be able to predict the amount of noise reduction to expect from a given shielding configuration. The data obtained on both subsonic and supersonic jets show that the noise sources associated with a given frequency of noise tend to move downstream, and therefore, would become more difficult to shield, as jet Mach number increases. The noise source localization data obtained on cold, shock-containing jets suggests that the constructive interference of sound waves that produces noise at a given frequency within a broadband shock noise hump comes primarily from a small number of shocks, rather than from all the shocks at the same time. The reflecting configuration data illustrates that the law of reflection must be satisfied in order for jet noise to reflect off of a surface to an observer, and depending on the relative locations of the jet, the surface, and the observer, only some of the jet noise sources may satisfy this requirement.

  2. Study of the characteristics of reconfigurable plasma antenna array

    SciTech Connect

    Alias, Nur Salihah; Dagang, Ahmad Nazri; Ali, Mohd Tarmizi

    2015-04-24

    This paper presents a design and simulation of a reconfigurable array of plasma antenna. The plasma column is used as radiating elements instead of metal to create an antenna. The advantages of the plasma antenna over the conventional antenna are its possible to change the operating parameters, such as the working pressure, input power, radius of the discharge tube, resonant frequency, and length of the plasma column. In addition, plasma antenna can be reconfigurable with respect to shape, frequency and radiation parameters in a very short time. The plasma discharge tube was designed with a length of 200 mm, the radius of the plasma column was 2.5 mm and the coupling sleeve was connected to the SMA as the ground. This simulation was performed by using the simulation software Computer Simulation Technology (CST). The frequency is set in the range of 1 GHz to 10 GHz. The performance of the designed antenna was analyzed in term of return loss, gain and radiation pattern. For reconfigurable plasma antenna array, it shows that the gain is increase when the number of antenna element is increase. The combination of the discharge tube and metal rod as an antenna array has been done, and the result shows that an array with the plasma element can achieve higher gain.

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

    SciTech Connect

    Chen, Chiping

    2013-08-26

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

  4. Decolorization of azodyes using the atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Lazovic, Sasa; Maletic, Dejan; Tomic, Natasa; Malovic, Gordana; Cvelbar, Uros; Dohcevic-Mitrovic, Zorana; Petrovic, Zoran Lj.

    2013-09-01

    Atmospheric pressure plasma jet operated in air/argon mixture is tested for decolorization of Bezactiv Orange V-3R dye used in the textile industry. The decolorization efficiency is determined by spectrophotometric measurements at 493.7 nm which corresponds to the breaking of dye N =N bond. The initial concentration of 50 mg/L of dye is reduced 50 times after 120 minutes of treatment by plasma. The results are compared to the efficiency of the suspended TiO2 powder and activated by an UV lamp (300 W). The radicals responsible for removal of the dye are OH and super-anion radical. It is found that efficiency of the plasma and TiO2 + UV is quite similar for the treatment times up to 60 min. After that, TiO2 shows higher decolorization rates (100 times reduction after 90 min). However, when plasma and TiO2 (but without the UV lamp) are applied together, it is found that there are synergetic effects and that the efficiency is increased. Plasma (less than 2 W) is not expected to produce high amounts of UV light in the atmospheric pressure. Supported by MESTD, RS, III41011 and ON 171037.

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

    NASA Astrophysics Data System (ADS)

    Gaitonde, Datta; Samimy, Mo

    2010-11-01

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

  6. Transient ejection phase modeling of a Plasma Synthetic Jet actuator

    NASA Astrophysics Data System (ADS)

    Laurendeau, F.; Chedevergne, F.; Casalis, G.

    2014-12-01

    For several years, a promising Plasma Synthetic Jet actuator for high-speed flow control has been under development at ONERA. So far, its confined geometry and small space-time scales at play have prevented its full experimental characterization. Complementary accurate numerical simulations are then considered in this study in order to provide a complete aerothermodynamic description of the actuator. Two major obstacles have to be overcome with this approach: the modeling of the energy deposited by the electric arc and the accurate computation of the transient response of the cavity generating the pulsed jet. To solve the first problem, an Euler solver coupled with an electric circuit model was used to evaluate the energy deposition in the cavity. Such a coupling is performed by considering the electric field between the two electrodes. The second issue was then addressed by injecting these source terms in large Eddy simulations of the entire actuator. Aerodynamic results were finally compared with Schlieren visualizations. Using the proposed methodology, the temporal evolution of the jet front is remarkably well predicted.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  8. Solitary and freak waves in superthermal plasma with ion jet

    NASA Astrophysics Data System (ADS)

    Abdelsalam, U. M.; Abdelsalam

    2013-06-01

    The nonlinear solitary and freak waves in a plasma composed of positive and negative ions, superthermal electrons, ion beam, and stationary dust particles have been investigated. The reductive perturbation method is used to obtain the Korteweg-de Vries (KdV) equation describing the system. The latter admits solitary wave solution, while the dynamics of the modulationally unstable wavepackets described by the KdV equation gives rise to the formation of freak/rogue excitation described by the nonlinear Schrödinger equation. In order to show that the characteristics of solitary and freak waves are influenced by plasma parameters, relevant numerical analysis of appropriate nonlinear solutions are presented. The results from this work predict nonlinear excitations that may associate with ion jet and superthermal electrons in Herbig-Haro objects.

  9. Plasma Interaction with International Space Station High Voltage Solar Arrays

    NASA Technical Reports Server (NTRS)

    Heard, John W.

    2002-01-01

    The International Space Station (ISS) is presently being assembled in low-earth orbit (LEO) operating high voltage solar arrays (-160 V max, -140 V typical with respect to the ambient atmosphere). At the station's present altitude, there exists substantial ambient plasma that can interact with the solar arrays. The biasing of an object to an electric potential immersed in plasma creates a plasma "sheath" or non-equilibrium plasma around the object to mask out the electric fields. A positively biased object can collect electrons from the plasma sheath and the sheath will draw a current from the surrounding plasma. This parasitic current can enter the solar cells and effectively "short out" the potential across the cells, reducing the power that can be generated by the panels. Predictions of collected current based on previous high voltage experiments (SAMPIE (Solar Array Module Plasma Interactions Experiment), PASP+ (Photovoltaic Array Space Power) were on the order of amperes of current. However, present measurements of parasitic current are on the order of several milliamperes, and the current collection mainly occurs during an "eclipse exit" event, i.e., when the space station comes out of darkness. This collection also has a time scale, t approx. 1000 s, that is much slower than any known plasma interaction time scales. The reason for the discrepancy between predictions and present electron collection is not understood and is under investigation by the PCU (Plasma Contactor Unit) "Tiger" team. This paper will examine the potential structure within and around the solar arrays, and the possible causes and reasons for the electron collection of the array.

  10. Plasma Interaction with International Space Station High Voltage Solar Arrays

    NASA Technical Reports Server (NTRS)

    Heard, John W.

    2002-01-01

    The International Space Station (ISS) is presently being assembled in low-earth orbit (LEO) operating high voltage solar arrays (-160 V max, -140 V typical with respect to the ambient atmosphere). At the station's present altitude, there exists substantial ambient plasma that can interact with the solar arrays. The biasing of an object to an electric potential immersed in plasma creates a plasma "sheath" or non-equilibrium plasma around the object to mask out the electric fields. A positively biased object can collect electrons from the plasma sheath and the sheath will draw a current from the surrounding plasma. This parasitic current can enter the solar cells and effectively "short out" the potential across the cells, reducing the power that can be generated by the panels. Predictions of collected current based on previous high voltage experiments (SAMPIE (Solar Array Module Plasma Interactions Experiment), PASP+ (Photovoltaic Array Space Power) were on the order of amperes of current. However, present measurements of parasitic current are on the order of several milliamperes, and the current collection mainly occurs during an "eclipse exit" event, i.e., when the space station comes out of darkness. This collection also has a time scale, t approx. 1000 s, that is much slower than any known plasma interaction time scales. The reason for the discrepancy between predictions and present electron collection is not understood and is under investigation by the PCU (Plasma Contactor Unit) "Tiger" team. This paper will examine the potential structure within and around the solar arrays, and the possible causes and reasons for the electron collection of the array.

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

    SciTech Connect

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

    2015-07-07

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  13. Effect of feed-gas humidity on nitrogen atmospheric-pressure plasma jet for biological applications.

    PubMed

    Stephan, Karl D; McLean, Robert J C; DeLeon, Gian; Melnikov, Vadim

    2016-11-14

    We investigate the effect of feed-gas humidity on the oxidative properties of an atmospheric-pressure plasma jet using nitrogen gas. Plasma jets operating at atmospheric pressure are finding uses in medical and biological settings for sterilization and other applications involving oxidative stress applied to organisms. Most jets use noble gases, but some researchers use less expensive nitrogen gas. The feed-gas water content (humidity) has been found to influence the performance of noble-gas plasma jets, but has not yet been systematically investigated for jets using nitrogen gas. Low-humidity and high-humidity feed gases were used in a nitrogen plasma jet, and the oxidation effect of the jet was measured quantitatively using a chemical dosimeter known as FBX (ferrous sulfate-benzoic acid-xylenol orange). The plasma jet using high humidity was found to have about ten times the oxidation effect of the low-humidity jet, as measured by comparison with the addition of measured amounts of hydrogen peroxide to the FBX dosimeter. Atmospheric-pressure plasma jets using nitrogen as a feed gas have a greater oxidizing effect with a high level of humidity added to the feed gas.

  14. Atmospheric Pressure Plasma Jet as a Dry Alternative to Inkjet Printing in Flexible Electronics

    NASA Technical Reports Server (NTRS)

    Gandhiraman, Ram Prasad; Lopez, Arlene; Koehne, Jessica; Meyyappan, M.

    2016-01-01

    We have developed an atmospheric pressure plasma jet printing system that works at room temperature to 50 deg C unlike conventional aerosol assisted techniques which require a high temperature sintering step to obtain desired thin films. Multiple jets can be configured to increase throughput or to deposit multiple materials, and the jet(s) can be moved across large areas using a x-y stage. The plasma jet has been used to deposit carbon nanotubes, graphene, silver nanowires, copper nanoparticles and other materials on substrates such as paper, cotton, plastic and thin metal foils.

  15. RF atmospheric plasma jet surface treatment of paper

    NASA Astrophysics Data System (ADS)

    Pawlat, Joanna; Terebun, Piotr; Kwiatkowski, Michał; Diatczyk, Jaroslaw

    2016-09-01

    A radio frequency RF atmospheric pressure plasma jet was used to enhance the wettability of cellulose-based paper of 90 g m-2 and 160 g m-2 grammage as a perspective platform for antibiotic sensitivity tests. Helium and argon were the carrier gases for oxygen and nitrogen; pure water and rapeseed oil were used for goniometric tests. The influence of the flow rate and gas type, the power of the discharge, and distance from the nozzle was examined. The surface structure was observed using an optical microscope. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra were investigated in order to determine whether cellulose degradation processes occurred. The RF plasma jet allowed us to decrease the surface contact angle without drastic changes in other features of the tested material. Experiments confirmed the significant influence of the distance between the treated sample and reactor nozzle, especially for treatment times longer than 15 s due to the greater concentration of reactive species at the surface of the sample, which decreases with distance—and their accumulation effect with time. The increase of discharge power plays an important role in decreasing the surface contact angle for times longer than 10 s. Higher power had a positive effect on the amount of generated active particles and facilitated the ignition of discharge. However, a too high value can cause a rise in temperature of the material and heat-caused damage.

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

    NASA Astrophysics Data System (ADS)

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

    1999-11-01

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

  17. Plasma action on helium flow in cold atmospheric pressure plasma jet experiments

    NASA Astrophysics Data System (ADS)

    Darny, T.; Pouvesle, J.-M.; Fontane, J.; Joly, L.; Dozias, S.; Robert, E.

    2017-10-01

    In this work, helium flow modifications, visualized by schlieren imaging, induced by the plasma generated in a plasma jet have been studied in conditions used for biomedical treatments (jet being directed downwards with a low helium flow rate). It has been shown that the plasma action can shift up to few centimeters downstream the effects of buoyancy, which allows to the helium flow to reach a target below in conditions for which it is not the case when the plasma is off. This study reveals the critical role of large and long lifetime negative ions during repetitive operations in the kHz regime, inducing strong modifications in the gas propagation. The cumulative added streamwise momentum transferred to ambient air surrounding molecules resulting from a series of applied voltage pulses induces a gradual built up of a helium channel on tens of millisecond timescale. In some conditions, a remarkable stable cylindrical helium channel can be generated to the target with plasma supplied by negative polarity voltage pulses whereas a disturbed flow results from positive polarity operation. This has a direct effect on air penetration in the helium channel and then on the reactive species production over the target which is of great importance for biomedical applications. It has also been shown that with an appropriate combination of negative and positive polarity pulses, it is possible to benefit from both polarity features in order to optimize the plasma plume propagation and plasma delivery to a target.

  18. A Design Procedure for a Scour Jet Array.

    DTIC Science & Technology

    1980-09-01

    include a water pump, a series of automatic control values and a control system which sequences the jets with the tidal currents in the area. The...studies by Krone (1962, 1974), gave the following deposition sequence . River born clay mineral particles are initially dispersed due to a sheathing of...NAVREGMEDCLINIC F. Hertlein 111, Pearl Harbor I NAVSCOLCECOFF C35 Port H-ueneme, CA: CO. Code C44A Port Hueneme. CA NAVSEASYSCOM Code tX)C-DG DiGeorge

  19. Low Temperature Plasma Surface Interactions: Atomic Layer Etching And Atmospheric Pressure Plasma Jet Modification Of Biomaterials

    NASA Astrophysics Data System (ADS)

    Oehrlein, Gottlieb

    2013-09-01

    Control of plasma-surface interactions is essential for successful application of low temperature plasma to materials processing. We review work performed in our laboratory in two areas: First, low pressure plasma surface interaction mechanisms aimed at achieving atomic precision in etching materials in the semiconductor industry. We discuss sequential reactions of surface passivation followed by directional low energy ion attack for ``volatile product'' removal to establish for what conditions self-limiting behavior required for Atomic Layer Etching (ALE) can be established using prototypical SiO2 -Si/fluorocarbon-Ar materials/etching systems. Second, studies of plasma-surface interactions related to application of a non-equilibrium atmospheric pressure plasma jet (APPJ) for modification of biomaterials are discussed. Changes in surface chemistry/biological activity of lipopolysaccharide (LPS) exposed to the APPJ plume/effluent in a controlled environment are reviewed. The results clarify how jet chemistry and interactions of plasma with the environment impact the consequences of APPJ-biomaterial-surface interactions. Based on collaborations with D. Metzler, S. Engelmann, R. Bruce, E. Joseph, E. Bartis, C. Hart, Q.-Y. Yang, J. Seog, T.-Y. Chung, H.-W. Chang, and D.B. Graves. We gratefully acknowledge funding from US Department of Energy (DE-SC0005105; DE-SC0001939) and National Science Foundation (CBET-1134273; PHY-1004256).

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

    SciTech Connect

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

    2012-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  2. Space Station Freedom solar array panels plasma interaction test facility

    NASA Technical Reports Server (NTRS)

    Martin, Donald F.; Mellott, Kenneth D.

    1989-01-01

    The Space Station Freedom Power System will make extensive use of photovoltaic (PV) power generation. The phase 1 power system consists of two PV power modules each capable of delivering 37.5 KW of conditioned power to the user. Each PV module consists of two solar arrays. Each solar array is made up of two solar blankets. Each solar blanket contains 82 PV panels. The PV power modules provide a 160 V nominal operating voltage. Previous research has shown that there are electrical interactions between a plasma environment and a photovoltaic power source. The interactions take two forms: parasitic current loss (occurs when the currect produced by the PV panel leaves at a high potential point and travels through the plasma to a lower potential point, effectively shorting that portion of the PV panel); and arcing (occurs when the PV panel electrically discharges into the plasma). The PV solar array panel plasma interaction test was conceived to evaluate the effects of these interactions on the Space Station Freedom type PV panels as well as to conduct further research. The test article consists of two active solar array panels in series. Each panel consists of two hundred 8 cm x 8 cm silicon solar cells. The test requirements dictated specifications in the following areas: plasma environment/plasma sheath; outgassing; thermal requirements; solar simulation; and data collection requirements.

  3. A model for straight and helical solar jets. II. Parametric study of the plasma beta

    NASA Astrophysics Data System (ADS)

    Pariat, E.; Dalmasse, K.; DeVore, C. R.; Antiochos, S. K.; Karpen, J. T.

    2016-11-01

    Context. Jets are dynamic, impulsive, well-collimated plasma events that develop at many different scales and in different layers of the solar atmosphere. Aims: Jets are believed to be induced by magnetic reconnection, a process central to many astrophysical phenomena. Within the solar atmosphere, jet-like events develop in many different environments, e.g., in the vicinity of active regions, as well as in coronal holes, and at various scales, from small photospheric spicules to large coronal jets. In all these events, signatures of helical structure and/or twisting/rotating motions are regularly observed. We aim to establish that a single model can generally reproduce the observed properties of these jet-like events. Methods: Using our state-of-the-art numerical solver ARMS, we present a parametric study of a numerical tridimensional magnetohydrodynamic (MHD) model of solar jet-like events. Within the MHD paradigm, we study the impact of varying the atmospheric plasma β on the generation and properties of solar-like jets. Results: The parametric study validates our model of jets for plasma β ranging from 10-3 to 1, typical of the different layers and magnetic environments of the solar atmosphere. Our model of jets can robustly explain the generation of helical solar jet-like events at various β ≤ 1. We introduces the new result that the plasma β modifies the morphology of the helical jet, explaining the different observed shapes of jets at different scales and in different layers of the solar atmosphere. Conclusions: Our results enable us to understand the energisation, triggering, and driving processes of jet-like events. Our model enables us to make predictions of the impulsiveness and energetics of jets as determined by the surrounding environment, as well as the morphological properties of the resulting jets.

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

    SciTech Connect

    Martens, Daniel; Hsu, Scott C.

    2012-08-16

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

  5. Development of atmospheric pressure plasma needle jet for sterilization applications

    NASA Astrophysics Data System (ADS)

    Elfa, Rizan Rizon; Ahmad, Mohd Khairul; Soon, Chin Fhong; Sahdan, Mohd Zainizan; Lias, Jais; Wibowo, Kusnanto Mukti; Bakar, Ahmad Shuhaimi Abu; Arshad, Mohd Khairuddin Md; Hashim, Uda; Nayan, Nafarizal

    2017-09-01

    Inactivation of bacteria or sterilization has been a major issue in the medical field, especially regarding of human safety, whereby, in a huge scenario fatality can be caused by hazardous bacteria. Often, E-coli as gram-negative bacteria are selected as a key indicator of proper sterilization process as E-coli is tough and dormant bacteria. The technology in sterilization has moved on from chemical, wet and irradiation sterilization to a high promising device such as atmospheric pressure plasma needle jet (APPNJ). It has been reported that atmospheric pressure plasma has provided bundle of advantages over earlier sterilization process. The APPNJ is developed in our lab using high frequency and high voltage neon transformer power supply connected to copper needle and copper sheet electrodes. The gas discharge is Ar gas flowing at 40 L/min through a quartz glass tube. The E-coli bacteria are self-cultured from waste water and then treated with APPNJ. The treatment processes are run into two difference gaps between the plasma orifice and sample with various treatment times. Only 40s is required by direct treatment to achieve 100% killing of E-coli. On the other hand, indirect treatment has inactivated 50% of the E-coli in 40s. In this study, direct and indirect effect of APPNJ to the E-coli can be observed which can be utilized into sterilization of bio-compatible material applications.

  6. LHCD experiments in high performance plasmas in JET

    NASA Astrophysics Data System (ADS)

    Ekedahl, A.; Baranov, Y.; Dobbing, J. A.; Fischer, B.; Goniche, M.; Gormezano, C.; Romero, J. A.; Schild, P.; Söldner, F. X.; Challis, C. D.; Sips, A. C. C.; Tubbing, B.

    1997-04-01

    Lower Hybrid Current Drive (LHCD) has been used for current profile shaping in the shear optimisation experiments in 1996/97 in JET. PLH≲3MW has been applied in the initial current ramp-up in order to control the internal inductance. An internal transport barrier with improved central electron confinement has been produced in this phase with LHCD alone. This has resulted in a peaking of the electron temperature profile and Te0 above 10keV at ne0⩽1.5×1019 m-3. The profile of the LH driven current, as determined by hard X-ray mesurements, is peaked at approximately mid-radius in these conditions. Good coupling of the LH waves has been obtained by the use of a near gas feed. This method reduces the risk of plasma-launcher interaction, since the launcher can be positioned in the shadow of the poloidal limiters. A reflection coefficient of 5% has been maintained at a plasma-launcher distance of 8 cm and PLH=5 MW has been coupled to divertor plasmas in L-mode with this method.

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

    SciTech Connect

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

    2009-05-04

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

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

    SciTech Connect

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

    2009-05-04

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

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

    SciTech Connect

    Chesler, Paul M.; Rajagopal, Krishna

    2016-05-17

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

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

    NASA Astrophysics Data System (ADS)

    Chesler, Paul M.; Rajagopal, Krishna

    2016-05-01

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

  11. Plasma-assisted cataluminescence sensor array for gaseous hydrocarbons discrimination.

    PubMed

    Na, Na; Liu, Haiyan; Han, Jiaying; Han, Feifei; Liu, Hualin; Ouyang, Jin

    2012-06-05

    Combining plasma activation and cross-reactivity of sensor array, we have developed a plasma-assisted cataluminescence (PA-CTL) sensor array for fast sensing and discrimination of gaseous hydrocarbons, which can be potentially used for fast diagnosis of lung cancer. Based on dielectric barrier discharge, a low-temperature plasma is generated to activate gaseous hydrocarbons with low cataluminescence (CTL) activities. Extremely increased CTL responses have been obtained, which resulted in a plasma assistance factor of infinity (∞) for some hydrocarbons. On a 4 × 3 PA-CTL sensor array made from alkaline-earth nanomaterials, gaseous hydrocarbons showed robust and unique CTL responses to generate characteristic patterns for fast discrimination. Because of the difference in the component of hydrocarbons in breath, exhaled breath samples from donors with and without lung cancer were tested, and good discrimination has been achieved by this technique. In addition, the feasibility of multidimentional detection based on temperature was confirmed. It had good reproducibility and gave a linear range of 65-6500 ng/mL or 77-7700 ppmv (R > 0.98) for CH(4) with a detection limit of 33 ng/mL (38 ppmv) on MgO. The PA-CTL sensor array is simple, low-cost, thermally stable, nontoxic, and has an abundance of alkaline-earth nanomaterials to act as sensing elements. This has expanded the applications of CTL-based senor arrays and will show great potential in clinical fast diagnosis.

  12. Influence of Plasma Jet Temperature Profiles in Arc Discharge Methods of Carbon Nanotubes Synthesis

    PubMed Central

    Raniszewski, Grzegorz; Wiak, Slawomir; Pietrzak, Lukasz; Szymanski, Lukasz; Kolacinski, Zbigniew

    2017-01-01

    One of the most common methods of carbon nanotubes (CNTs) synthesis is application of an electric-arc plasma. However, the final product in the form of cathode deposit is composed of carbon nanotubes and a variety of carbon impurities. An assay of carbon nanotubes produced in arc discharge systems available on the market shows that commercial cathode deposits contain about 10% CNTs. Given that the quality of the final product depends on carbon–plasma jet parameters, it is possible to increase the yield of the synthesis by plasma jet control. Most of the carbon nanotubes are multiwall carbon nanotubes (MWCNTs). It was observed that the addition of catalysts significantly changes the plasma composition, effective ionization potential, the arc channel conductance, and in effect temperature of the arc and carbon elements flux. This paper focuses on the influence of metal components on plasma-jet forming containing carbon nanotubes cathode deposit. The plasma jet temperature control system is presented. PMID:28336884

  13. Sterilization of Staphylococcus Aureus by an Atmospheric Non-Thermal Plasma Jet

    NASA Astrophysics Data System (ADS)

    Liu, Xiaohu; Hong, Feng; Guo, Ying; Zhang, Jing; Shi, Jianjun

    2013-05-01

    An atmospheric non-thermal plasma jet was developed for sterilizing the Staphylococcus aureus (S. aureus). The plasma jet was generated by dielectric barrier discharge (DBD), which was characterized by electrical and optical diagnostics. The survival curves of the bacteria showed that the plasma jet could effectively inactivate 106 cells of S. aureus within 120 seconds and the sterilizing efficiency depended critically on the discharge parameter of the applied voltage. It was further confirmed by scanning electron microscopy (SEM) that the cell morphology was seriously damaged by the plasma treatment. The plasma sterilization mechanism of S. aureus was attributed to the active species of OH, N2+ and O, which were generated abundantly in the plasma jet and characterized by OES. Our findings suggest a convenient and low-cost way for sterilization and inactivation of bacteria.

  14. Effective dose delivery in atmospheric pressure plasma jets for plasma medicine: a model predictive control approach

    NASA Astrophysics Data System (ADS)

    Gidon, Dogan; Graves, David B.; Mesbah, Ali

    2017-08-01

    Atmospheric pressure plasma jets (APPJs) have been identified as a promising tool for plasma medicine. This paper aims to demonstrate the importance of using model-based feedback control strategies for safe, reproducible, and therapeutically effective application of APPJs for dose delivery to a target substrate. Key challenges in model-based control of APPJs arise from: (i) the multivariable, nonlinear nature of system dynamics, (ii) the need for constraining the system operation within an operating region that ensures safe plasma treatment, and (iii) the cumulative, nondecreasing nature of dose metrics. To systematically address these challenges, we propose a model predictive control (MPC) strategy for real-time feedback control of a radio-frequency APPJ in argon. To this end, a lumped-parameter, physics-based model is developed for describing the jet dynamics. Cumulative dose metrics are defined for quantifying the thermal and nonthermal energy effects of the plasma on substrate. The closed-loop performance of the MPC strategy is compared to that of a basic proportional-integral control system. Simulation results indicate that the MPC stategy provides a versatile framework for dose delivery in the presence of disturbances, while the safety and practical constraints of the APPJ operation can be systematically handled. Model-based feedback control strategies can lead to unprecedented opportunities for effective dose delivery in plasma medicine.

  15. Correlation between helium atmospheric pressure plasma jet (APPJ) variables and plasma induced DNA damage

    NASA Astrophysics Data System (ADS)

    Adhikari, Ek R.; Ptasinska, Sylwia

    2016-09-01

    A helium atmospheric pressure plasma jet (APPJ) source with a dielectric capillary and two tubular electrodes was used to induce damage in aqueous plasmid DNA. The fraction of different types of DNA damage (i.e., intact or undamaged, double strand breaks (DSBs), and single strand breaks (SSBs)) that occurred as the result of plasma irradiation was quantified through analysis of agarose gel electrophoresis images. The total DNA damage increased with an increase in both flow rate and duration of irradiation, but decreased with an increase in distance between the APPJ and sample. The average power of the plasma was calculated and the length of APPJ was measured for various flow rates and voltages applied. The possible effects of plasma power and reactive species on DNA damage are discussed.

  16. Detailed heat transfer coefficient distributions under an array of impinging jets with coolant extraction

    SciTech Connect

    Huang, Y.; Ekkad, S.V.; Han, J.C.

    1996-12-31

    Jet impingement cooling is a high performance technique for heat transfer enhancement. Local heat transfer distributions are presented for an array of jets impinging on a target plate with a series of coolant extraction holes. The flow enters the pressure channel, impinges on the target plate and exits toward the sides and through the coolant extraction holes. The impingement plate has four rows of 12 jet holes and the target plate has three rows of 11 coolant extraction holes. The jet holes and the coolant extraction holes have the same diameters and are staggered such that the air impinging from the jet hole does not exit directly through the extraction hole. The detailed heat transfer coefficient distributions are measured using a transient technique and liquid crystal coating. Results are presented for a range of jet Reynolds numbers between 4,000 and 20,000. The effect of crossflow is also studied by changing the exit opening of the impingement channel to provide three different spent air exit directions. Heat transfer results for the target plate with coolant extraction are compared with those without coolant extraction at the same flow conditions.

  17. Automated control of linear constricted plasma source array

    DOEpatents

    Anders, Andre; Maschwitz, Peter A.

    2000-01-01

    An apparatus and method for controlling an array of constricted glow discharge chambers are disclosed. More particularly a linear array of constricted glow plasma sources whose polarity and geometry are set so that the contamination and energy of the ions discharged from the sources are minimized. The several sources can be mounted in parallel and in series to provide a sustained ultra low source of ions in a plasma with contamination below practical detection limits. The quality of film along deposition "tracks" opposite the plasma sources can be measured and compared to desired absolute or relative values by optical and/or electrical sensors. Plasma quality can then be adjusted by adjusting the power current values, gas feed pressure/flow, gas mixtures or a combination of some or all of these to improve the match between the measured values and the desired values.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  20. An atmospheric pressure quasiuniform planar plasma jet generated by using a dielectric barrier configuration

    SciTech Connect

    Li Qing; Takana, Hidemasa; Nishiyama, Hideya; Pu Yikang

    2011-06-13

    A stable nonthermal quasiuniform planar plasma jet, originating from a planar dielectric duct with a rectangular exit and issuing into ambient air at atmospheric pressure, is reported in the present work. Current-voltage characteristics, one discharge current pulse per sinusoidal half voltage cycle, show that the discharge is not filamentary. Its spatial uniformity in the transverse direction is shown to be excellent by monitoring optical emission spectra in the jet core region except jet boundaries. This is possibly resulted from high preionization in the upstream region, and it is a challenge to the traditional single streamer explanation for nonthermal plasma jets.

  1. Periodic steamwise variations of heat transfer coefficients for incline and staggered arrays of circular jets with crossflow of spent air

    NASA Technical Reports Server (NTRS)

    Florschuetz, L. W.; Metzger, D. E.; Berry, R. A.

    1979-01-01

    Heat transfer characteristics were measured for inline and staggered arrays of circular jets impinging on a surface parallel to the jet orifice plate. The impinging flow was constrained to exit in a single direction along the channel formed by the jet plate and the heat transfer surface. In this configuration the air discharged from upstream transverse rows of jet holes imposes a crossflow of increasing magnitude on the succeeding downstream jet rows. Streamwise heat transfer coefficient profiles were determined for a streamwise resolution of one-third the streamwise hole spacing, utilizing a specially constructed test surface.

  2. Production and provision mechanisms of OH radical of an atmospheric-pressure helium plasma jet

    NASA Astrophysics Data System (ADS)

    Yonemori, Seiya; Ono, Ryo; Oda, Tetsuji

    2012-10-01

    An atmospheric-pressure helium plasma jet is getting much attention because of its low heat load. It is known that active species such as OH radical play important role in many plasma processes, for example, in plasma medical care or in plasma sterilization. When using the plasma jet for surface treatment, it is important that the amount of OH radical provided into objectives. We measured OH density in the vicinity of the surface of objectives using laser induced fluorescence (LIF). The plasma jet was generated when AC 8 kHz, 10 kV was applied. When the plasma jet extended onto the dry glass surface, the maximum OH density was 0.2 ppm. On the other hand, the maximum OH density was 1 ppm when the plasma jet extended onto the wet surface. In addition, time-evolution of OH density between two successive voltage pulses was measured. On the edge of the plasma jet, OH density was at maximum and rapidly decreased between two pulses. Those results suggest that there are three ways of OH production; first, the dissociation of H2O included in discharge gas; secondly, the dissociation of H2O included in the ambient air; finally, the dissociation of H2O evaporates from the wet surface.

  3. Investigation of flow structure and heat transfer characteristics in an array of impinging slot jets

    NASA Astrophysics Data System (ADS)

    Ozmen, Yucel; Ipek, Gokhan

    2016-04-01

    In this study, an experimental and numerical study is carried out to investigate flow field and heat transfer characteristics of unconfined and confined arrays of four turbulent slot air jets issuing from the lower surface and impinging normally on the upper surface. Pressure and temperature distributions on the surfaces were obtained for the nozzle-to-plate spacing (H/W) of 1-10 and for the Reynolds numbers in the range of 5000-15,000 at the jet-to-jet centerline spacing (S/W) of 9. The effects of jet confinement, Reynolds number and nozzle-to-plate spacing on the flow structure and heat transfer were investigated. Pressure distributions are obtained experimentally and numerically, while heat transfer distributions are computed numerically. It is observed that the surface pressure distributions on both impingement and confinement plates are independent from the Reynolds number, while they have been largely affected from the nozzle-to-plate spacing. Jet confinement causes a considerable difference at the flow field especially for small nozzle-to-plate spacings. Subatmospheric regions are not observed for unconfined jet. However three different types of subatmospheric pressure regions occur on both impingement and confinement plates for confined jet. Nusselt distributions on the impingement plate for both unconfined and confined jet configurations depend on the Reynolds number and nozzle-to-plate spacing. It is concluded that there is a strong correlation between subatmospheric regions and secondary peaks in Nusselt distributions. The numerical results obtained using the Realizable k-ɛ turbulence model is in good accordance with the experimental results for moderate values of nozzle-to-plate spacings.

  4. Fluidic Oscillator Array for Synchronized Oscillating Jet Generation

    NASA Technical Reports Server (NTRS)

    Koklu, Mehti (Inventor)

    2016-01-01

    A fluidic oscillator array includes a plurality of fluidic-oscillator main flow channels. Each main flow channel has an inlet and an outlet. Each main flow channel has first and second control ports disposed at opposing sides thereof, and has a first and a second feedback ports disposed at opposing sides thereof. The feedback ports are located downstream of the control ports with respect to a direction of a fluid flow through the main flow channel. The system also includes a first fluid accumulator in fluid communication with each first control port and each first feedback port, and a second fluid accumulator in fluid communication with each second control port and each second feedback port.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  6. The effect of lower hybrid waves on JET plasma rotation

    NASA Astrophysics Data System (ADS)

    Nave, M. F. F.; Kirov, K.; Bernardo, J.; Brix, M.; Ferreira, J.; Giroud, C.; Hawkes, N.; Hellsten, T.; Jonsson, T.; Mailloux, J.; Ongena, J.; Parra, F.; Contributors, JET

    2017-03-01

    This paper reports on observations of rotation in JET plasmas with lower hybrid current drive. Lower hybrid (LH) has a clear impact on rotation. The changes in core rotation can be either in the co- or counter-current directions. Experimental features that could determine the direction of rotation were investigated. Changes from co- to counter-rotation as the q-profile evolves from above unity to below unity suggests that magnetic shear could be important. However, LH can drive either co- or counter-rotation in discharges with similar magnetic shear and at the same plasma current. It is not clear if a slightly lower density is significant. A power scan at fixed density, shows a lower hybrid power threshold around 3 MW. For smaller LH powers, counter rotation increases with power, while for larger powers a trend towards co-rotation is found. The estimated counter-torque from the LH waves, would not explain the observed angular frequencies, neither would it explain the observation of co-rotation.

  7. 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.

  8. Analysis of jet-airfoil interaction noise sources by using a microphone array technique

    NASA Astrophysics Data System (ADS)

    Fleury, Vincent; Davy, Renaud

    2016-03-01

    The paper is concerned with the characterization of jet noise sources and jet-airfoil interaction sources by using microphone array data. The measurements were carried-out in the anechoic open test section wind tunnel of Onera, Cepra19. The microphone array technique relies on the convected, Lighthill's and Ffowcs-Williams and Hawkings' acoustic analogy equation. The cross-spectrum of the source term of the analogy equation is sought. It is defined as the optimal solution to a minimal error equation using the measured microphone cross-spectra as reference. This inverse problem is ill-posed yet. A penalty term based on a localization operator is therefore added to improve the recovery of jet noise sources. The analysis of isolated jet noise data in subsonic regime shows the contribution of the conventional mixing noise source in the low frequency range, as expected, and of uniformly distributed, uncorrelated noise sources in the jet flow at higher frequencies. In underexpanded supersonic regime, a shock-associated noise source is clearly identified, too. An additional source is detected in the vicinity of the nozzle exit both in supersonic and subsonic regimes. In the presence of the airfoil, the distribution of the noise sources is deeply modified. In particular, a strong noise source is localized on the flap. For high Strouhal numbers, higher than about 2 (based on the jet mixing velocity and diameter), a significant contribution from the shear-layer near the flap is observed, too. Indications of acoustic reflections on the airfoil are also discerned.

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

    SciTech Connect

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

    2014-05-15

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

  10. Compact collimated fiber optic array diagnostic for railgun plasma experiments

    SciTech Connect

    Tang, V; Solberg, J; Ferriera, T; Tully, L; Stephan, P

    2008-10-02

    We have developed and tested a compact collimated sixteen channel fiber optic array diagnostic for studying the light emission of railgun armature plasmas with {approx}mm spatial and sub-{micro}s temporal resolution. The design and operational details of the diagnostic are described. Plasma velocities, oscillation, and dimension data from the diagnostic for the Livermore Fixed Hybrid Armature experiment are presented and compared with 1-D simulations. The techniques and principles discussed allow the extension of the diagnostic to other railgun and related dense plasma experiments.

  11. Compact collimated fiber optic array diagnostic for railgun plasmas.

    PubMed

    Tang, V; Solberg, J M; Ferriera, T J; Tully, L K; Stephan, P L

    2009-01-01

    We developed and tested a compact collimated 16 channel fiber optic array diagnostic for studying the light emission of railgun armature plasmas with approximately millimeter spatial and submicrosecond temporal resolution. The design and operational details of the diagnostic are described. Plasma velocities, oscillation, and dimension data from the diagnostic for the Livermore fixed hybrid armature experiment are presented and compared with one-dimensional simulations. The techniques and principles discussed allow the extension of the diagnostic to other railgun and related dense plasma experiments.

  12. Compact collimated fiber optic array diagnostic for railgun plasmas

    SciTech Connect

    Tang, V.; Solberg, J. M.; Ferriera, T. J.; Tully, L. K.; Stephan, P. L.

    2009-01-15

    We developed and tested a compact collimated 16 channel fiber optic array diagnostic for studying the light emission of railgun armature plasmas with approximately millimeter spatial and submicrosecond temporal resolution. The design and operational details of the diagnostic are described. Plasma velocities, oscillation, and dimension data from the diagnostic for the Livermore fixed hybrid armature experiment are presented and compared with one-dimensional simulations. The techniques and principles discussed allow the extension of the diagnostic to other railgun and related dense plasma experiments.

  13. Development of a New-type of Plasma Jet by using a Modified Pseudospark Discharge

    NASA Astrophysics Data System (ADS)

    Watanabe, Masayuki; Kamada, Takaharu; Mizutani, Akihide; Murakami, Yukimasa; Nagasawa, Atsushi; Minoru, Itagaki

    1999-11-01

    A new type of plasma jet by using a modified pseudospark discharge(PSD) is proposed. The PSD is a low-pressure gas discharge with a pair of parallel disk electrode. In this discharge, the single plane cathode is replaced by a cathode with a circular hole on the axis. The cathode electrode has a cylindrical cavity behind the circular hole. PSD is characterized as follows: (i) Discharge is formed through the electrode holes. (ii) Breakdown voltage is a function of plasma pressure. (Paschen'law-like relation) (iii) In the hollow cathode discharge, the current is lager than that for the parallel plane gap (hollow cathode effect). (iv) High current glow discharge is formed. For our plasma jet experiment, geometry of electrode is modified. The force of plasma acceleration is Lorentz force (j\\x81 B), similar to MPD arc jet. The difference between MPD arc jet and our plasma jet is the mode of discharge. The discharge of our plasma jet is not an arc mode but a high current glow mode, as a result, the impurity production into the plasma is low and lifetime of electrodes is long. As the high current discharge and its pinch effect, high temperature and low impurity plasma is formed and spouted from the anode hole.

  14. Electro-physical property of plasma jet generated by burning chemicals as antenna

    NASA Astrophysics Data System (ADS)

    Zhong-Cai, Yuan; Jia-Ming, Shi; Xiao-Po, Wu; Zong-Shen, Chen; Zong-Shen

    2013-02-01

    The application of pulsed power to transient radiofrequency/microwave radiation for warhead/projectile payloads is currently a significant area of research. In this paper, the far-field radiative property of a plasma antenna is analyzed. Then, a plasma jet is generated by burning chemicals, in which the electron concentration and collision frequency are diagnosed, and the electric conductance is calculated. Finally, the feasibility to apply the plasma jet as antenna is investigated by analyzing the radiative pattern. The dependency of pattern on plasma electron density, collision frequency, and plasma wake radius is calculated and analyzed.

  15. Thermal behavior of bovine serum albumin after exposure to barrier discharge helium plasma jet

    NASA Astrophysics Data System (ADS)

    Jijie, R.; Pohoata, V.; Topala, I.

    2012-10-01

    Non-thermal plasma jets at atmospheric pressure are useful tools nowadays in plasma medicine. Various applications are tested such as cauterization, coagulation, wound healing, natural and artificial surfaces decontamination, and sterilization. In order to know more about the effects of gas plasma on biological supramolecules, we exposed protein powders to a barrier discharge helium plasma jet. Then, spectroscopic investigations were carried out in order to obtain information on protein secondary, tertiary, and quaternary structures. We obtained a reduction of the protein alpha-helix content after the plasma exposure and a different behavior, for both thermal denaturation/renaturation kinetics and thermal aggregation process.

  16. Simulation of Motion, Heating, and Breakup of Molten Metal Droplets in the Plasma Jet at Plasma-Arc Spraying

    NASA Astrophysics Data System (ADS)

    Kharlamov, M. Yu.; Krivtsun, I. V.; Korzhyk, V. N.; Ryabovolyk, Y. V.; Demyanov, O. I.

    2015-04-01

    The mathematical model for the process of plasma-arc wire spraying is proposed, which describes behavior of molten metal droplets in the plasma jet, allowing for the processes of their deformation and gas-dynamic breakup. Numerical analysis of the processes of motion, heating, and breakup of molten metal droplets, detached from the sprayed wire at plasma-arc spraying of coatings, was performed. It is shown that during molten droplets movement in the plasma jet their multiple breakup takes place, leading to formation of sprayed particles with dimensions much smaller than dimensions of initial droplets, detached from the sprayed wire tip.

  17. Review of biased solar array - Plasma interaction studies

    NASA Technical Reports Server (NTRS)

    Stevens, N. J.

    1981-01-01

    Possible high voltage surface interactions on the Solar Electric Propulsion System (SEPS) are examined, with particular regard for potential effects on SEPS performance. The SEPS is intended for use for geosynchronous and planetary missions, and derives power from deployed solar cell arrays which are susceptible to collecting ions and electrons from the charged and thermal particle environment of space. The charge exchange plasma which provides the thrust force can also enhance the natural charged particle environment and increase interactions between the thrust system and the biased solar array surface. Tests of small arrays have shown that snapover, where current collection becomes proportional to the panel area, can be avoided by larger cell sizes. Arcing is predicted to diminish with larger array sizes, while the problems of efflux environments are noted to be as yet undefined and require further study.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    SciTech Connect

    Srivastava, Nimisha; Wang Chuji

    2011-09-01

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

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

    SciTech Connect

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

    2011-06-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  2. Plasma turbulence measured with fast frequency swept reflectometry in JET H-mode plasmas

    NASA Astrophysics Data System (ADS)

    Clairet, F.; Sirinelli, A.; Meneses, L.; Contributors, JET

    2016-12-01

    In this work we present recent achievements to provide precise measurements of turbulence on JET H-mode plasmas using frequency sweeping reflectometry diagnostic. The plasma density fluctuations retrieved from swept reflected signals, first initiated with the Tore Supra reflectometry (Heuraux et al 2003 Rev. Sci. Instrum. 74 1501, Vermare et al 2006 Nucl. Fusion 46 S743, Gerbaud et al 2006 Rev. Sci. Instrum. 77 10E928), provides a radial profile of the density fluctuation level and its spectral structure. Using the complete set of the JET X-mode fast sweeping heterodyne reflectometers we have determined the temporal dynamic of the density fluctuation profile from the edge to the center during an H-mode discharge. At the L-H transition, the turbulence reduction seems to occur, at first, simultaneously from the edge to the center then deepens at the edge at ρ ~ 0.95 and this deepening propagates toward the center with a steepening of the wavenumber spectra. During an edge localized mode (ELM) event, a substantial density fluctuations increase has been observed with a localized turbulent wave front propagating toward the center accompanying a particle transport. We also show that type-III ELMs sustain a steady and high level of plasma turbulence compare to type-I.

  3. Hinode EIS and XRT Observations of Hot Jets in Coronal Holes - Does the Plasma Escape?

    NASA Astrophysics Data System (ADS)

    Baker, D.; van Driel-Gesztelyi, L.; Kamio, S.; Culhane, J. L.; Harra, L. K.; Sun, J.; Young, P. R.; Matthews, S. A.

    2008-09-01

    X-ray jets have been detected in the extreme ultraviolet (EUV) and soft X-ray observations of Hinode's EIS and XRT instruments. Both instruments were used to observe the jets in polar and on-disk coronal holes (CHs). Here, we present a multi-wavelength study of an X-ray jet and its associated bright point found in an equatorial CH on 19 June 2007. Light curves (LCs) in 22 different emission lines were compared to that of Hinode/XRT. As we found in a previous study of two polar X-ray jets, this jet shows a post-jet increase in its EUV LCs. The post-jet enhancement appears cooler than the jet. We suggest this feature arises because the hot plasma of the jet, having failed to reach escape speeds, cools and falls back along the near vertical paths expected to be created by reconnection with open field lines of CHs. In addition to the increase in post-jet EUV intensity, we found tentative evidence of impact heating possibly caused by the fall-back of plasma.

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

    NASA Astrophysics Data System (ADS)

    Mirpour, Shahriar; Ghoranneviss, Mahmood; Shahgoli, Farhad

    2011-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

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

    PubMed

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

    2014-07-01

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

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

    DOE PAGES

    Chesler, Paul M.; Rajagopal, Krishna

    2016-05-17

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

  8. Fabrication of flexible microlens array through vapor-induced room temperature dewetting on plasma treated Parylene-C.

    PubMed

    Xiaopeng Bi; Wen Li

    2014-01-01

    Microlens arrays have been widely used as an essential component in many optical systems. The conventional fabrication techniques, such as ink-jet printing, photoresist thermal reflow, grayscale photolithography, and LIGA process have some drawbacks in aspects of process complexity and high fabrication cost. This paper presents a low-temperature, rapid and cost-effective method to successfully generate SU-8 microlens arrays on biocompatible Parylene-C surfaces. Vapor-induced SU-8 dewetting has been achieved on chemically modified Parylene-C surfaces that were selectively pre-treated with O(2) or SF(6) plasma. By this technique, the SU-8 droplets are self-organized onto desired positions to form a microlens array. This method is also suitable for production of microlens array on curved surfaces. The progress of dewetting has been studied by both experiment and simulation.

  9. Fundamental Studies of Transient, Atmospheric-Pressure, Small-Scale Plasmas

    DTIC Science & Technology

    2017-01-23

    e.g. plasma brush) were explored for surface decontamination against pathogenic bacteria and biofilms, as well as for treatment of cervical cancer, in...pressure plasma jets and jet arrays (e.g. plasma brush) were explored for surface decontamination against pathogenic bacteria and biofilms, as well as...atmospheric pressure plasma jets and jet arrays (e.g. plasma brush) were explored for surface decontamination against pathogenic bacteria and biofilms, as

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

    NASA Technical Reports Server (NTRS)

    Calcote, H. F.

    1978-01-01

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

  11. Modeling the generation and propagation of plasma jets

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    A 2-D fluid model was used to study plasma jets initiated in a dielectric barrier discharge configuration consisting of a dielectric tube (3 mm inner radius) surrounded by a grounded electrode and propagating in air at atmospheric pressure. A voltage pulse of +5 kV with a rise time of 50 ns is applied to a annular electrode inside the tube. Helium is maintained at atmospheric pressure inside the tube by a gas flow with a velocity of some 10 m/s. Electron impact ionization of ground state atoms is the only ionization process considered, and the secondary electron emission coefficient due to ion impact is supposed to be constant. Dielectric boundary conditions are applied on the tube walls, and electrons and ions at the surface are assumed to recombine instantaneously when a charged particle of opposite sign arrives at the same surface element. The computational volume extends a finite distance past the exit plane of the dielectric tube and the computational boundaries are supposed to be at ground potential. The helium/air density profiles past the exit plane of the tube are assumed to follow scaling laws for laminar flow with parameters adjusted to fit available experimental results. Consistent with experiment, the model predicts the initiation of a streamer during the voltage rise which propagates preferentially in the easily-ionized helium potential core.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  13. Plasma Surface Presented as Array of Virtual Ports

    SciTech Connect

    Kyrytsya, V.; Koch, R.

    2009-11-26

    Calculations aimed at representing the plasma-vacuum boundary condition in real space are presented. Some ideas about how this representation can be used for power coupling analysis and antenna modeling are put forward. The relation between tangential electric and magnetic fields on the plasma surface is linear and customary expressed in the spectral domain for every partial wave via 2x2 plasma impedance matrix - Z{sup p}(k{sub y},K{sub z}). In this work, the tangential fields E-vector{sub t} and B-vector{sub t} on the plasma surface are projected on a suitably chosen set of basis functions. Then the linear operator relating the components E-vector{sub t} and B-vector{sub t} expressed in such a way is derived from the known matrix Z{sup p}(k{sub y},K{sub z}). It is shown that in this representation the plasma surface has properties similar to the array of ports of a microwave system and can be formally described by a corresponding impedance matrix in the way it is done in microwave analysis. The obtained representation can be exploited for deeper understanding of the RF power coupling to the plasmas, antenna modeling, measurements of plasma electromagnetic properties and for plasma modeling with suitably designed structures or metamaterials.

  14. Discrimination of trace nitroaromatics using linear discriminant analysis on aerosol jet printed fluorescent sensor arrays

    NASA Astrophysics Data System (ADS)

    Bolse, N.; Eckstein, R.; Schend, M.; Habermehl, A.; Hernandez-Sosa, G.; Eschenbaum, C.; Lemmer, U.

    2017-05-01

    In this work, we report on fluorescent sensor arrays fabricated by aerosol jet printing on glass substrates to detect explosives-related nitroaromatic species. The printed sensor arrays consist of six different fluorescent polymers responding to nitroaromatic vapors through a photo-induced electron transfer. This results in a quenched fluorescence proportional to the vapor concentration. Distinct fluorescence quenching patterns are detected for nitroaromatic species including nitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene. The detected fingerprints are evaluated at low concentrations of only 1, 3 and 10 parts-per-billion in air. Linear discriminant analysis is used to train each sensor array enabling the discrimination of the target analyte vapors. To investigate the reproducibility of multiple sensor arrays on a single substrate, the measured fluorescence quenching patterns are used to benchmark the linear discriminant models. For this purpose, the target analytes and vapor concentrations are predicted for each sensor array. On average, we report low and reproducible misclassification rates of about 4 % indicating excellent discriminatory abilities at low concentrations close to the detection limits. We conclude that digital printing of fluorescent polymers offers the potential to realize low-cost sensor arrays for a reliable detection of trace explosives.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  16. Induction of apoptosis in human breast cancer cells by a pulsed atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    By using an atmospheric pressure plasma jet driven by pulsed dc voltage with repetition rate of several tens of kilohertz, we were able to induce apoptosis in cultured human breast cancer cells (MCF-7). The apoptotic changes in cells with plasma treatment were detected by flow cytometry and fluorescence staining assay. A significant portion of these cells was observed to exhibit the apoptotic fragmentation. Helium plasma with additive O2 gas was found to be effective in the induction of apoptosis. This plasma jet provides an effective mode of human breast cancer cell therapy.

  17. Non-thermal plasma jet without electrical shock for biomedical applications

    NASA Astrophysics Data System (ADS)

    Baik, Ku Youn; Kang, Han Lim; Kim, Junseong; Park, Shin Young; Bang, Ji Yun; Uhm, Han S.; Choi, Eun Ha; Cho, Guangsup

    2013-10-01

    A plasma jet without an electrical shock was generated through a Y-shaped tube in which voltages with opposite phases were applied to a pair of tubes. The plasma plume generated at the intersection had a plasma potential of a 60-90 V and high concentrations of reactive species sufficient to induce a high level of lethality on gram-negative bacteria on a tissue mimic. The selective lethality of bacteria on an epithelial-cell-containing tissue mimic could be modulated using oxidant and antioxidant chemicals, thereby leading to the possibility of a shock-reduced plasma jet for biomedical applications.

  18. Three-dimensional MHD simulation of the Caltech plasma jet experiment: first results

    SciTech Connect

    Zhai, Xiang; Bellan, Paul M.; Li, Hui; Li, Shengtai E-mail: pbellan@caltech.edu E-mail: sli@lanl.gov

    2014-08-10

    Magnetic fields are believed to play an essential role in astrophysical jets with observations suggesting the presence of helical magnetic fields. Here, we present three-dimensional (3D) ideal MHD simulations of the Caltech plasma jet experiment using a magnetic tower scenario as the baseline model. Magnetic fields consist of an initially localized dipole-like poloidal component and a toroidal component that is continuously being injected into the domain. This flux injection mimics the poloidal currents driven by the anode-cathode voltage drop in the experiment. The injected toroidal field stretches the poloidal fields to large distances, while forming a collimated jet along with several other key features. Detailed comparisons between 3D MHD simulations and experimental measurements provide a comprehensive description of the interplay among magnetic force, pressure, and flow effects. In particular, we delineate both the jet structure and the transition process that converts the injected magnetic energy to other forms. With suitably chosen parameters that are derived from experiments, the jet in the simulation agrees quantitatively with the experimental jet in terms of magnetic/kinetic/inertial energy, total poloidal current, voltage, jet radius, and jet propagation velocity. Specifically, the jet velocity in the simulation is proportional to the poloidal current divided by the square root of the jet density, in agreement with both the experiment and analytical theory. This work provides a new and quantitative method for relating experiments, numerical simulations, and astrophysical observation, and demonstrates the possibility of using terrestrial laboratory experiments to study astrophysical jets.

  19. Study of the expansion characteristics of a pulsed plasma jet in air

    NASA Astrophysics Data System (ADS)

    Xuewei, ZHAO; Yonggang, YU; Shanshan, MANG; Xiaochun, XUE

    2017-04-01

    In the background of electrothermal-chemical (ETC) emission, an investigation has been conducted on the characteristics of a freely expanding pulsed plasma jet in air. The evolutionary process of the plasma jet is experimentally investigated using a piezoelectric pressure sensor and a digital high-speed video system. The variation relation in the extended volume, axial displacement and radial displacement of the pulsed plasma jet in atmosphere with time under different discharge voltages and jet breaking pressures is obtained. Based on experiments, a two-dimensional axisymmetric unsteady model is established to analyze the characteristics of the two-phase interface and the variation of flow-field parameters resulting from a pulsed plasma jet into air at a pressure of 1.5–3.5 MPa under three nozzle diameters (3 mm, 4 mm and 5 mm, respectively). The images of the plasma jet reveal a changing shape process, from a quasi-ellipsoid to a conical head and an elongated cylindrical tail. The axial displacement of the jet is always larger than that along the radial direction. The extended volume reveals a single peak distribution with time. Compared to the experiment, the numerical simulation agrees well with the experimental data. The parameters of the jet field mutate at the nozzle exit with a decrease in the parameter pulse near the nozzle, and become more and more gradual and close to environmental parameters. Increasing the injection pressure and nozzle diameter can increase the parameters of the flow field such as the expansion volume of the pulsed plasma jet, the size of the Mach disk and the pressure. In addition, the turbulent mixing in the expansion process is also enhanced.

  20. Study of the expansion characteristics of a pulsed plasma jet in air

    NASA Astrophysics Data System (ADS)

    Zhao, Xuewei; Yu, Yonggang; Mang, Shanshan; Xue, Xiaochun

    2017-04-01

    In the background of electrothermal-chemical (ETC) emission, an investigation has been conducted on the characteristics of a freely expanding pulsed plasma jet in air. The evolutionary process of the plasma jet is experimentally investigated using a piezoelectric pressure sensor and a digital high-speed video system. The variation relation in the extended volume, axial displacement and radial displacement of the pulsed plasma jet in atmosphere with time under different discharge voltages and jet breaking pressures is obtained. Based on experiments, a two-dimensional axisymmetric unsteady model is established to analyze the characteristics of the two-phase interface and the variation of flow-field parameters resulting from a pulsed plasma jet into air at a pressure of 1.5-3.5 MPa under three nozzle diameters (3 mm, 4 mm and 5 mm, respectively). The images of the plasma jet reveal a changing shape process, from a quasi-ellipsoid to a conical head and an elongated cylindrical tail. The axial displacement of the jet is always larger than that along the radial direction. The extended volume reveals a single peak distribution with time. Compared to the experiment, the numerical simulation agrees well with the experimental data. The parameters of the jet field mutate at the nozzle exit with a decrease in the parameter pulse near the nozzle, and become more and more gradual and close to environmental parameters. Increasing the injection pressure and nozzle diameter can increase the parameters of the flow field such as the expansion volume of the pulsed plasma jet, the size of the Mach disk and the pressure. In addition, the turbulent mixing in the expansion process is also enhanced.

  1. Jet flavor tomography of quark gluon plasmas at RHIC and LHC.

    PubMed

    Buzzatti, Alessandro; Gyulassy, Miklos

    2012-01-13

    A new Monte Carlo model of jet quenching in nuclear collisions, CUJET1.0, is applied to predict the jet flavor dependence of the nuclear modification factor for fragments f=π,D,B,e(-) from quenched jet flavors g,u,c,b in central collisions at RHIC and LHC. The nuclear modification factors for different flavors are predicted to exhibit a novel level crossing pattern over a transverse momentum range 5jet-medium dynamics in quark gluon plasmas.

  2. Laboratory experiments on plasma jets in a magnetic field using high-power lasers

    NASA Astrophysics Data System (ADS)

    Nishio, K.; Sakawa, Y.; Kuramitsu, Y.; Morita, T.; Ide, T.; Kuwada, M.; Koga, M.; Kato, T.; Norimatsu, T.; Gregory, C.; Woolsey, N.; Murphy, C.; Gregori, G.; Schaar, K.; Diziere, A.; Koenig, M.; Pelka, A.; Wang, S.; Dong, Q.; Li, Y.; Takabe, H.

    2013-11-01

    The experiments to simulate astrophysical jet generation are performed using Gekko XII (GXII) HIPER laser system at the Institute of Laser Engineering. In the experiments a fast plasma flow generated by shooting a CH plane (10 μm thickness) is observed at the rear side of the plane. By separating the focal spot of the main beams, a non-uniform plasma is generated. The non-uniform plasma flow in an external magnetic field (0.2˜0.3 T) perpendicular to the plasma is more collimated than that without the external magnetic field. The plasma β, the ratio between the plasma and magnetic pressure, is ≫ 1, and the magnetic Reynolds number is ˜150 in the collimated plasma. It is considered that the magnetic field is distorted by the plasma flow and enhances the jet collimation.

  3. Control of ROS and RNS productions in liquid in atmospheric pressure plasma-jet system

    NASA Astrophysics Data System (ADS)

    Uchida, Giichiro; Ito, Taiki; Takenaka, Kosuke; Ikeda, Junichiro; Setsuhara, Yuichi

    2016-09-01

    Non-thermal plasma jets are of current interest in biomedical applications such as wound disinfection and even treatment of cancer tumors. Beneficial therapeutic effects in medical applications are attributed to excited species of oxygen and nitrogen from air. However, to control the production of these species in the plasma jet is difficult because their production is strongly dependent on concentration of nitrogen and oxygen from ambient air into the plasma jet. In this study, we analyze the discharge characteristics and the ROS and RNS productions in liquid in low- and high-frequency plasma-jet systems. Our experiments demonstrated the marked effects of surrounding gas near the plasma jet on ROS and RNS productions in liquid. By controlling the surround gas, the O2 and N2 main plasma jets are selectively produced even in open air. We also show that the concentration ratio of NO2- to H2O2 in liquid is precisely tuned from 0 to 0.18 in deionized water by changing N2 gas ratio (N2 / (N2 +O2)) in the main discharge gas, where high NO2- ratio is obtained at N2 gas ratio at N2 / (N2 +O2) = 0 . 8 . The low-frequency plasma jet with controlled surrounding gas is an effective plasma source for ROS and RNS productions in liquid, and can be a useful tool for biomedical applications. This study was partly supported by a Grant-in-Aid for Scientific Research on Innovative Areas ``Plasma Medical Innovation'' (24108003) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).

  4. High fusion performance from deuterium-tritium plasmas in JET

    NASA Astrophysics Data System (ADS)

    Keilhacker, M.; Gibson, A.; Gormezano, C.; Lomas, P. J.; Thomas, P. R.; Watkins, M. L.; Andrew, P.; Balet, B.; Borba, D.; Challis, C. D.; Coffey, I.; Cottrell, G. A.; DeEsch, H. P. L.; Deliyanakis, N.; Fasoli, A.; Gowers, C. W.; Guo, H. Y.; Huysmans, G. T. A.; Jones, T. T. C.; Kerner, W.; König, R. W. T.; Loughlin, M. J.; Maas, A.; Marcus, F. B.; Nave, M. F. F.; Rimini, F. G.; Sadler, G. J.; Sharapov, S. E.; Sips, G.; Smeulders, P.; Söldner, F. X.; Taroni, A.; Tubbing, B. J. D.; von Hellermann, M. G.; Ward, D. J.; JET Team

    1999-02-01

    High fusion power experiments using DT mixtures in ELM-free H mode and optimized shear regimes in JET are reported. A fusion power of 16.1 MW has been produced in an ELM-free H mode at 4.2 MA/3.6 T. The transient value of the fusion amplification factor was 0.95+/-0.17, consistent with the high value of nDT(0)τEdiaTi(0) = 8.7 × 1020+/-20% m-3 s keV, and was maintained for about half an energy confinement time until excessive edge pressure gradients resulted in discharge termination by MHD instabilities. The ratio of DD to DT fusion powers (from separate but otherwise similar discharges) showed the expected factor of 210, validating DD projections of DT performance for similar pressure profiles and good plasma mixture control, which was achieved by loading the vessel walls with the appropriate DT mix. Magnetic fluctuation spectra showed no evidence of Alfvénic instabilities driven by alpha particles, in agreement with theoretical model calculations. Alpha particle heating has been unambiguously observed, its effect being separated successfully from possible isotope effects on energy confinement by varying the tritium concentration in otherwise similar discharges. The scan showed that there was no, or at most a very weak, isotope effect on the energy confinement time. The highest electron temperature was clearly correlated with the maximum alpha particle heating power and the optimum DT mixture; the maximum increase was 1.3+/-0.23 keV with 1.3 MW of alpha particle heating power, consistent with classical expectations for alpha particle confinement and heating. In the optimized shear regime, clear internal transport barriers were established for the first time in DT, with a power similar to that required in DD. The ion thermal conductivity in the plasma core approached neoclassical levels. Real time power control maintained the plasma core close to limits set by pressure gradient driven MHD instabilities, allowing 8.2 MW of DT fusion power with nDT(0)τEdiaTi(0

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

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

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

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

    SciTech Connect

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

    2007-06-25

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

  7. The control effect in a detached laminar boundary layer of an array of normal synthetic jets

    NASA Astrophysics Data System (ADS)

    Valenzuela Calva, Fernando; Avila Rodriguez, Ruben

    2016-11-01

    In this work, 3D numerical simulations of an array of three normal circular synthetic jets embedded in an attached laminar boundary layer that separates under the influence of an inclined flap are performed for flow separation control. At the beginning of the present study, three cases are used to validate the numerical simulation with data obtained from experiments. The experimental data is chosen based on the cases which presented higher repeatability and reliability. Simulations showed reasonable agreement when compared with experiments. The simulations are undertaken at three synthetic jet operating conditions, i.e. Case A: L = 2, VR = 0.32; Case B: L = 4, VR = 0.64 and Case C: L = 6, VR = 0.96. The vortical structures produced for each synthetic jet operating condition are hairpin vortices for Case A and tilted vortices for Case B and C, respectively. By examining the spatial wall shear stress variations, the effect on the boundary layer prior to separation of the middle synthetic jet is evaluated. For effective flow control, produced at a relatively low the finding from this study suggests that hairpin vortical structures are more desirable structures. Universidad Nacional Autonoma de Mexico.

  8. HIGH VELOCITY PRECESSING JETS FROM THE WATER FOUNTAIN IRAS 18286-0959 REVEALED BY VERY LONG BASELINE ARRAY OBSERVATIONS

    SciTech Connect

    Yung, Bosco H. K.; Nakashima, Jun-ichi; Kwok, Sun; Imai, Hiroshi; Deguchi, Shuji; Diamond, Philip J.

    2011-11-10

    We report the results of multi-epoch Very Long Baseline Array observations of the 22.2 GHz H{sub 2}O maser emission associated with the 'water fountain' IRAS 18286-0959. We suggest that this object is the second example of a highly collimated bipolar precessing outflow traced by H{sub 2}O maser emission, the other is W 43A. The detected H{sub 2}O emission peaks are distributed over a velocity range from -50 km s{sup -1} to 150 km s{sup -1}. The spatial distribution of over 70% of the identified maser features is found to be highly collimated along a spiral jet (jet 1) extended southeast to northwest; the remaining features appear to trace another spiral jet (jet 2) with a different orientation. The two jets form a 'double-helix' pattern which lies across {approx}200 mas. The maser distribution is reasonably fit by a model consisting of two bipolar precessing jets. The three-dimensional velocities of jet 1 and jet 2 are derived to be 138 km s{sup -1} and 99 km s{sup -1}, respectively. The precession period of jet 1 is about 56 years. For jet 2, three possible models are tested and they give different values for the kinematic parameters. We propose that the appearance of two jets is the result of a single driving source with significant proper motion.

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

    SciTech Connect

    Moser, Auna L. Hsu, Scott C.

    2015-05-15

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

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

    NASA Astrophysics Data System (ADS)

    Iancu, Edmond; Wu, Bin

    2016-12-01

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

  11. Properties of Atmospheric Pressure Ar Plasma Jet Depending on Treated Dielectric Material

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    Atmospheric pressure plasma jet operated in argon was utilized to modify surfaces of glass, acrylic, and PTFE dielectrics. This paper describes the influence of the dielectric substrate on operation and properties of plasma. Two modes of operation (each of those have two patterns) were described. The transition from one mode to another, values of the dissipated power, and spreading of plasma over the dielectric surfaces strongly depended on the substrate material. Additionally, three methods of plasma spreading estimation were presented and discussed.

  12. [Investigation on the Spectral Characteristics of a Plasma Jet in Atmospheric Argon Glow Discharge].

    PubMed

    Li, Xue-chen; Zhang, Chun-yan; Li, Ji-yuan; Bao, Wen-ting

    2015-12-01

    Plasma jet is a kind of important plasma source at atmospheric pressure. In recent years, it becomes an important hot topic in the field of low temperature plasma. In this paper, using a tungsten needle and a tungsten wire mesh, a direct-current excited jet is developed to operate in argon at atmospheric pressure. In the atmospheric pressure argon, the plasma jet can produce a stable plasma plume. By using the method of emission spectroscopy, the parameters of the plasma plume are investigated. The discharge emits dazzling white light from the area between the tungsten needle electrode and the wire mesh electrode. A plasma plume with a flame shape appears outside the tungsten wire mesh electrode. For a constant value of voltage (U = 13.5 kV), the length of the plasma plume increases with the gas flow rate. For a constant value of the gas flow rate(10 L · min⁻¹), the length of the plasma plume increases with the voltage. The voltage is inversely proportional to the current under the constant gas flow rate. In other words, the voltage decreases with the discharge current, which indicates that a glow discharge is formed in the plasma jet. Optical emission spectrum in 300 to 800 nm is collected from the direct-current excited plasma jet. By Boltzmann plot method, the excited electron temperature of the plasma plume is investigated as a function of the applied voltage or the gas flow rate. Results show that the excited electron temperature increases with decreasing applied voltage under the constant gas flow. Moreover, it increases with decreasing the gas flow under the constant voltage. Based on the discharge theory, these experimental phenomena are explained qualitatively. These results are of great importance to the development of atmospheric pressure uniform discharge plasma source and its application in industrial field.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  14. Radial magnetic compression in the expelled jet of a plasma deflagration accelerator

    NASA Astrophysics Data System (ADS)

    Loebner, Keith T. K.; Underwood, Thomas C.; Mouratidis, Theodore; Cappelli, Mark. A.

    2016-02-01

    A spectroscopic study of a pulsed plasma deflagration accelerator is carried out that confirms the existence of a strong compression in the emerging jet at the exit plane of the device. An imaging spectrometer is used to collect broadened Hα emission from a transaxial slice of the emerging jet at high spatial resolution, and the radial plasma density profile is computed from Voigt fits of the Abel inverted emissivity profiles. The plasma temperature, determined via Doppler broadening of impurity line emission, is compared against the temperature predictions of a radial magnetohydrodynamic equilibrium model applied to the measured density profiles. Empirical scaling laws developed for the plasma density, combined with the measured and predicted temperatures, indicate that a radially equilibrated Z-pinch is formed within the expelled plasma jet at the exit plane during the deflagration process.

  15. Radial magnetic compression in the expelled jet of a plasma deflagration accelerator

    SciTech Connect

    Loebner, Keith T. K. Underwood, Thomas C.; Mouratidis, Theodore; Cappelli, Mark A.

    2016-02-29

    A spectroscopic study of a pulsed plasma deflagration accelerator is carried out that confirms the existence of a strong compression in the emerging jet at the exit plane of the device. An imaging spectrometer is used to collect broadened Hα emission from a transaxial slice of the emerging jet at high spatial resolution, and the radial plasma density profile is computed from Voigt fits of the Abel inverted emissivity profiles. The plasma temperature, determined via Doppler broadening of impurity line emission, is compared against the temperature predictions of a radial magnetohydrodynamic equilibrium model applied to the measured density profiles. Empirical scaling laws developed for the plasma density, combined with the measured and predicted temperatures, indicate that a radially equilibrated Z-pinch is formed within the expelled plasma jet at the exit plane during the deflagration process.

  16. Optical Emission Spectroscopy of an Atmospheric Pressure Plasma Jet During Tooth Bleaching Gel Treatment.

    PubMed

    Šantak, Vedran; Zaplotnik, Rok; Tarle, Zrinka; Milošević, Slobodan

    2015-11-01

    Optical emission spectroscopy was performed during atmospheric pressure plasma needle helium jet treatment of various tooth-bleaching gels. When the gel sample was inserted under the plasma plume, the intensity of all the spectral features increased approximately two times near the plasma needle tip and up to two orders of magnitude near the sample surface. The color change of the hydroxylapatite pastille treated with bleaching gels in conjunction with the atmospheric pressure plasma jet was found to be in correlation with the intensity of OH emission band (309 nm). Using argon as an additive to helium flow (2 L/min), a linear increase (up to four times) of OH intensity and, consequently, whitening (up to 10%) of the pastilles was achieved. An atmospheric pressure plasma jet activates bleaching gel, accelerates OH production, and accelerates tooth bleaching (up to six times faster).

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

    SciTech Connect

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

    2008-01-15

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

  18. Generation of ultra-fast cumulative water jets by sub-microsecond underwater electrical explosion of conical wire arrays

    NASA Astrophysics Data System (ADS)

    Shafer, D.; Gurovich, V. Tz.; Gleizer, S.; Gruzinsky, K.; Krasik, Ya. E.

    2015-12-01

    The results of experiments with underwater electrical explosion of modified conical arrays of copper and aluminum wires are presented. A pulsed generator producing a 550 kA-amplitude current with a 400 ns rise time was used in the explosion of the arrays. The array explosion generates water flows converging at the axis of the cone. This flow generates a fast-moving water jet with a velocity exceeding 1.8 × 105 cm/s, which was observed being ejected from the surface of the water covering the array. The positions of the water jet were measured by multiple-exposure fast framing imaging. In experiments, the apex angle of the array, the thickness of the water layer above the arrays, or the material of the wires was altered, which changed the resulting velocities and shapes of the emitted jets. A model that considers the converging stationary flow of a slightly compressible fluid is suggested. The velocities and shapes of the jets obtained by this model agree well with the experimentally measured jet velocities.

  19. Double planar wire array as a compact plasma radiation source

    SciTech Connect

    Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Williamson, K. M.; Yilmaz, M. F.; Shrestha, I.; Ouart, N. D.; Osborne, G. C.; Rudakov, L. I.; Chuvatin, A. S.; Coverdale, C. A.; Deeney, C.

    2008-03-15

    Magnetically compressed plasmas initiated by a double planar wire array (DPWA) are efficient radiation sources. The two rows in a DPWA implode independently and then merge together at stagnation producing soft x-ray yields and powers of up to 11.5 kJ/cm and more than 0.4 TW/cm, higher than other planar arrays or low wire-number cylindrical arrays on the 1 MA Zebra generator. DPWA, where precursors form in two stages, produce a shaped radiation pulse and radiate more energy in the main burst than estimates of implosion kinetic energy. High radiation efficiency, compact size (as small as 3-5 mm wide), and pulse shaping show that the DPWA is a potential candidate for ICF and radiation physics research.

  20. Radiographic research of the Bi plasma jet formed by the vacuum arc discharge

    NASA Astrophysics Data System (ADS)

    Artyomov, A. P.; Rousskikh, A. G.; Fedunin, A. V.; Chaikovsky, S. A.; Zhigalin, A. S.; Oreshkin, V. I.

    2017-05-01

    The results of experiments on a soft x-ray radiography (≈ 1-2 keV) of a bismuth plasma formed by the high-current vacuum arc discharge are represented. The plasma gun with the arc current ≈ 60 kA and the current rise time ≈ 7 μs was used to produce the Bi plasma jet. The compact pulsed radiograph XPG-1 (250 kA, 220 ns) with an X-pinch load consisting of four Mo wires with a diameter 25 μm was used as a source of the soft X-ray radiation. The X-ray backlighting images of the researched plasma jet and the Bi step-wedge with a step thickness of ≈ 100 nm were recorded simultaneously in the course of the experiment. A comparison of the plasma jet x-ray image with the current trace has enabled to estimate dependencies of the linear mass on the arc current. The experiments have shown that when the arc current density reaches ≈ 3·105 A/cm2, the evaporation rate of the electrode material reaches ≈ 100 μg/μs, that under the plasma velocity ≈ 0.5 cm/μs, provides a plasma jet linear mass ≈ 200 μg/cm. At a distance of ≈ 1-2 mm from the arc cathode surface, the sharp increase of the jet linear mass (up to ≈ 500 μg/cm) occurred.

  1. Donut shape plasma jet plumes generated by microwave pulses even without air mole fractions

    NASA Astrophysics Data System (ADS)

    Chen, Zhaoquan; Liu, Xiaodong; Zou, Changlin; Song, Xiao; Li, Ping; Hu, Yelin; Qiu, Hanbiao; Kudryavtsev, A. A.; Zhu, Mengzhou

    2017-01-01

    It is well known that the plasma jets driven by lower frequency voltages or pulsed DC power supply normally present with donut shaped cross sections, especially at where the diffused air mole fractions are less than 0.01. Thence, it is interesting to further study whether the donut shape is still in truth for the pulsed microwave plasma jet or not. In this letter, the cross sectional structures of atmospheric pressure plasma jet plumes driven by pulsed microwaves have been experimented on a cylindrical coaxial transmission line resonator. The plasma jet plumes demonstrate particular characteristics, like argon plasma with a donut shape but helium plasma with an uniform lighten cross section, despite whether the air mole fraction exists or not. For argon discharge, the fast images show that the donut shaped cross section only occurs at the end of each microwave pulses. In combination with helium discharge, the cross sectional patterns are immediately determined by the dominant ionization front of the plasma jet plumes, which are resonantly generated by the local enhanced electric field of ionization waves.

  2. Development of a new atmospheric pressure cold plasma jet generator and application in sterilization

    NASA Astrophysics Data System (ADS)

    Cheng, Cheng; Liu, Peng; Xu, Lei; Zhang, Li-Ye; Zhan, Ru-Juan; Zhang, Wen-Rui

    2006-07-01

    This paper reports that a new plasma generator at atmospheric pressure, which is composed of two homocentric cylindrical all-metal tubes, successfully generates a cold plasma jet. The inside tube electrode is connected to ground, the outside tube electrode is connected to a high-voltage power supply, and a dielectric layer is covered on the outside tube electrode. When the reactor is operated by low-frequency (6 kHz-20 kHz) AC supply in atmospheric pressure and argon is steadily fed as a discharge gas through inside tube electrode, a cold plasma jet is blown out into air and the plasma gas temperature is only 25-30°C. The electric character of the discharge is studied by using digital real-time oscilloscope (TDS 200-Series), and the discharge is capacitive. Preliminary results are presented on the decontamination of E.colis bacteria and Bacillus subtilis bacteria by this plasma jet, and an optical emission analysis of the plasma jet is presented in this paper. The ozone concentration generated by the plasma jet is 1.0×1016cm-3 which is acquired by using the ultraviolet absorption spectroscopy.

  3. Technology Development for Large Radio Arrays at the Jet Propulsion Laboratory

    NASA Astrophysics Data System (ADS)

    Jones, Dayton L.; Preston, R.; Navarro, R.; Wagstaff, K.; Mattmann, C.; D'Addario, L.; Thompson, D.; Majid, W.; Lazio, J.

    2011-05-01

    Future radio arrays are likely to include far more antennas than current arrays, ultimately culminating in the Square Kilometre Array. During the past 1.5 years JPL personnel have been working on technologies to address the challenges of such large arrays, including lower power digital signal processing, real-time data adaptive algorithms, and large-scale data archiving and mining. Power consumption by digital electronics may be a dominant component of the operating costs of large arrays. The choice of architecture for cross-correlation of thousands of antennas can have an orders-of-magnitude impact on power consumption. A power efficient architecture for a very-large-N array has been found. A second area of development at JPL is adaptive algorithms to perform real-time processing of data in high volume data flows, when storage of raw data for later processing is not an option. Algorithms to enable real-time detection of fast radio transients are being tested on the VLBA, and will be deployed as part of the CRAFT collaboration on ASKAP and potentially at other observatories. Finally, large radio arrays will produce extremely large data archives. We are working on applying a scalable framework for managing and mining large data archives to radio array needs. This framework is JPL's open source Process Control System, initially built for archiving data from NASA Earth Science missions and now used in a number of applications outside of astronomy. This work has been carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  6. Impact of the JET ITER-like wall on H-mode plasma fueling

    NASA Astrophysics Data System (ADS)

    Wiesen, S.; Brezinsek, S.; Wischmeier, M.; De la Luna, E.; Groth, M.; Jaervinen, A. E.; de la Cal, E.; Losada, U.; de Aguilera, A. M.; Frassinetti, L.; Gao, Y.; Guillemaut, C.; Harting, D.; Meigs, A.; Schmid, K.; Sergienko, G.; contributors, JET

    2017-06-01

    JET ITER-like wall (ILW) experiments show that the edge density evolution is strongly linked with the poloidal distribution of the ionization source. The fueling profile in the JET-ILW is more delocalized as compared to JET-C (JET with carbon-based plasma-facing components PFCs). Compared to JET-C the H-mode pedestal fueling cycle is dynamically influenced by a combination of plasma-wall interaction features, in particular: (1) edge-localized modes (ELMs) induced energetic particles are kinetically reflected on W divertor PFCs leading to distributed refueling away from the divertor depending on the divertor plasma configuration, (2) delayed molecular re-emission and outgassing of particles being trapped in W PFCs (bulk-W at the high field side and W-coated CFCs at the low field side) with different fuel content and (3) outgassing from Be co-deposits located on top of the high-field side baffle region shortly after the ELM. In view of the results of a set of well diagnosed series of JET-ILW type-I ELMy H-mode discharges with good statistics, the aforementioned effects are discussed in view of H-mode pedestal fueling capacity. The ongoing modelling activities with the focus on coupled core-edge plasma simulations and plasma-wall interaction are described and discussed also in view of possible code improvements required.

  7. Modeling and Simulation for Nanoparticle Plasma Jet Diagnostic Probe for Runaway Electron Beam-Plasma Interaction

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    The C60 nanoparticle plasma jet (NPPJ) rapid injection into a tokamak major disruption is followed by C60 gradual fragmentation along plasma-traversing path. The result is abundant C ion concentration in the core plasma enhancing the potential to probe and diagnose the runaway electrons (REs) during different phases of their dynamics. A C60/C NPPJ of 75 mg, high-density (>1023 m-3) , hyper-velocity (>4 km/s), and uniquely fast response-to-delivery time ( 1 ms) has been demonstrated on a test bed. It can rapidly and deeply deliver enough mass to increase electron density to 2.4x1021 m-3, 60 times larger than typical DIII-D pre-disruption value. We will present the results of our on-going work on: 1) self-consistent model for RE current density evolution (by Dreicer mechanism and ``avalanche'') focused on the effect of fast and deep deposition of C ions, 2) improvement of single C60q+ fragmenting ion penetration model through tokamak B(R)-field and post-TQ plasma, and 3) simulation of C60q+ PJ penetration through the DIII-D characteristic 2 T B-field to the RE beam central location by using the Hybrid Electro-Magnetic 2D code (HEM-2D. Work supported by US DOE DE-SC0015776 Grant.

  8. Plasma/particle interaction in subsonic argon/helium thermal plasma jets

    SciTech Connect

    Swank, W.D.; Fincke, J.R.; Haggard, D.C.

    1993-04-01

    Understanding the behavior of a particle and the interactions between a particle and the plasma surrounding it is important to the development and optimization of the plasma spray coating process. This is an experimental study of the interaction between a subsonic thermal plasma jet and injected nickel-aluminum particles. The velocity, temperature and composition of the gas flow field is mapped using an enthalpy probe/mass spectrometer system. The particle flow field is examined by simultaneously measuring the in-flight size, velocity, and temperature of individual particles. The complex interaction between the gas and particle flow fields is examined by combining the two sets of data. Particle and gas temperatures and velocities are compared in the vicinity of a nominal substrate standoff distance and axially along the median particle trajectory. The temperature and velocity difference is shown to vary substantially depending on the particle`s trajectory. By the time a particle on the median trajectory reaches the nominal substrate stand off of 63.5 mm it is transferring it`s heat and momentum to the plasma gas.

  9. Plasma/particle interaction in subsonic argon/helium thermal plasma jets

    SciTech Connect

    Swank, W.D.; Fincke, J.R.; Haggard, D.C.

    1993-01-01

    Understanding the behavior of a particle and the interactions between a particle and the plasma surrounding it is important to the development and optimization of the plasma spray coating process. This is an experimental study of the interaction between a subsonic thermal plasma jet and injected nickel-aluminum particles. The velocity, temperature and composition of the gas flow field is mapped using an enthalpy probe/mass spectrometer system. The particle flow field is examined by simultaneously measuring the in-flight size, velocity, and temperature of individual particles. The complex interaction between the gas and particle flow fields is examined by combining the two sets of data. Particle and gas temperatures and velocities are compared in the vicinity of a nominal substrate standoff distance and axially along the median particle trajectory. The temperature and velocity difference is shown to vary substantially depending on the particle's trajectory. By the time a particle on the median trajectory reaches the nominal substrate stand off of 63.5 mm it is transferring it's heat and momentum to the plasma gas.

  10. Modeling the plasma chemistry of stratospheric Blue Jet streamers

    NASA Astrophysics Data System (ADS)

    Winkler, Holger; Notholt, Justus

    2014-05-01

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

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

    SciTech Connect

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

    2015-07-15

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

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

    NASA Astrophysics Data System (ADS)

    Topala, Ionut; Nastuta, Andrei

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

  13. Jet array impingement flow distributions and heat transfer characteristics. Effects of initial crossflow and nonuniform array geometry. [gas turbine engine component cooling

    NASA Technical Reports Server (NTRS)

    Florschuetz, L. W.; Metzger, D. E.; Su, C. C.; Isoda, Y.; Tseng, H. H.

    1982-01-01

    Two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered. The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer surface. The configurations considered are intended to model those of interest in current and contemplated gas turbine airfoil midchord cooling applications. The effects of an initial crossflow which approaches the array through an upstream extension of the channel are considered. Flow distributions as well as heat transfer coefficients and adiabatic wall temperatures resolved to one streamwise hole spacing were measured as a function of the initial crossflow rate and temperature relative to the jet flow rate and temperature. Both Nusselt number profiles and dimensionless adiabatic wall temperature (effectiveness) profiles are presented and discussed. Special test results which show a significant reduction of jet orifice discharge coefficients owing to the effect of a confined crossflow are also presented, along with a flow distribution model which incorporates those effects. A nonuniform array flow distribution model is developed and validated.

  14. Enhanced plasma current collection from weakly conducting solar array blankets

    NASA Technical Reports Server (NTRS)

    Hillard, G. Barry

    1993-01-01

    Among the solar cell technologies to be tested in space as part of the Solar Array Module Plasma Interactions Experiment (SAMPIE) will be the Advanced Photovoltaic Solar Array (APSA). Several prototype twelve cell coupons were built for NASA using different blanket materials and mounting techniques. The first conforms to the baseline design for APSA which calls for the cells to be mounted on a carbon loaded Kapton blanket to control charging in GEO. When deployed, this design has a flexible blanket supported around the edges. A second coupon was built with the cells mounted on Kapton-H, which was in turn cemented to a solid aluminum substrate. A final coupon was identical to the latter but used germanium coated Kapton to control atomic oxygen attack in LEO. Ground testing of these coupons in a plasma chamber showed considerable differences in plasma current collection. The Kapton-H coupon demonstrated current collection consistent with exposed interconnects and some degree of cell snapover. The other two coupons experienced anomalously large collection currents. This behavior is believed to be a consequence of enhanced plasma sheaths supported by the weakly conducting carbon and germanium used in these coupons. The results reported here are the first experimental evidence that the use of such materials can result in power losses to high voltage space power systems.

  15. Impingement Flow Heat Transfer Measurements of Turbine Blades Using a Jet Array

    DTIC Science & Technology

    1994-08-01

    wooawrrculatmo sysam 62 pm t 4.9 TlAR of aceilito wth ja pkoue box ......... 62 Rpmg 4. 10 TIU gravity uwtuald fw ating vahv desiged to tisoae the pe, i...fatigue and higher sre problems for the designer. With hot section design life equiments now 50% of the airframe life, users are demanding reliable...different arrays of impinging jets. This gives an indication of where hot spots or problem areas might occur on the blade. The heat transfer or cooling

  16. Self-positioning microlens arrays prepared using ink-jet printing

    NASA Astrophysics Data System (ADS)

    Lu, Jhih-Ping; Huang, Wen-Kuei; Chen, Fang-Chung

    2009-07-01

    We have employed ink-jet printing (IJP) technology to fabricate self-positioning microlens arrays (MLAs). The glass substrates were first prepatterned through microcontact printing (μCP) hydrophobic self-assembled monolayers (SAMs) to divide the surface into hydrophobic and hydrophilic regions. After IJP of the hydrophilic prepolymer liquids, the lenses were effectively repelled by the patterned SAMs. We obtained high-quality MLAs having diameters of 75 and 100 μm after polymerization of the prepolymers. The lenses' shapes could be controlled by varying the number of printed droplets.

  17. Interaction of a solar array with an ion thruster due to the charge-exchange plasma

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.

    1976-01-01

    The generation of a charge exchange plasma by a thruster, the transport of this plasma to the solar array, and the interaction of the solar array with the plasma after it arrives are all described. The generation of this plasma is described accurately from thruster geometry and operating conditions. The transport of the charge exchange plasma was studied experimentally with a 15 cm thruster. A model was developed for simple thruster array configurations. A variety of experiments were surveyed for the interaction of the plasma at the solar array.

  18. Solar Array Module Plasma Interaction Experiment (SAMPIE): Technical requirements document

    NASA Technical Reports Server (NTRS)

    Hillard, G. Barry; Ferguson, Dale C.

    1992-01-01

    The Solar Array Module Plasma Interactions Experiment (SAMPIE) is a NASA shuttle space flight experiment scheduled for launch in early 1994. The SAMPIE experiment will investigate plasma interactions of high voltage space power systems in low earth orbit. Solar cell modules, representing several technologies, will be biased to high voltages to characterize both arcing and plasma current collection. Other solar modules, specially modified in accordance with current theories of arcing and breakdown, will demonstrate the possibility of arc suppression. Finally, several test modules will be included to study the basic nature of these interactions. The science and technology goals for the project are defined in the Technical Requirements Document (TRD) which is presented here.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  20. Bactericidal effect of plasma jet with helium flowing through 3% hydrogen peroxide against Enterococcus faecalis.

    PubMed

    Zhou, Xin-Cai; Li, Yu-Lan; Liu, De-Xi; Cao, Ying-Guang; Lu, Xin-Pei

    2016-11-01

    The aim of the present study was to assess the antimicrobial activity of plasma jet with helium (He) flowing through 3% hydrogen peroxide in root canals infected with Enterococcus faecalis. A total of 42 single-rooted anterior teeth were prepared, sterilized, inoculated with an E. faecalis suspension and incubated for 7 days. Next, the teeth were randomly divided into six experimental groups (including groups treated by plasma jet with or without He for different time durations) and one control group treated without plasma. The number of surviving bacteria in each canal was determined by counting the colony forming units (CFU)/ml on nutrient agar plates. The results indicated that statistically significant reduction in CFU/ml (P<0.005) existed for all treatment groups relative to the control group. The greatest reductions in CFU/ml were observed for Group 3 (7.027 log unit reduction) and Group 2 (6.237 log unit reduction), which were treated by plasma jet sterilization with He flowing through 3% hydrogen peroxide for 4 min or for 2 min, respectively. In addition, the reduction in Group 3 was significantly greater compared with that in Group 2 or in the groups treated by plasma jet sterilization without He flowing through 3% hydrogen peroxide for 1, 2 or 4 min. In conclusion, plasma jet with or without He flowing through 3% hydrogen peroxide can effectively sterilized root canals infected with E. faecalis and should be considered as an alternative method for root canal disinfection in endodontic treatments.

  1. Long and Highly Flexible Micro-Plasma Jet Device for Endoscopic Treatments

    NASA Astrophysics Data System (ADS)

    Kim, Jae Young; Cutshall, Daniel; Hawkins, Thomas; Ballato, John; Kim, Sung-O.

    2012-10-01

    A long and highly flexible micro-plasma jet device made of hollow-core optical fiber has been proposed for use in endoscopic treatment. The fiber which is used has an inner diameter of 350 μm and an outer diameter of 700 μm. The plasma jet device was 165 cm in length and merely 2 millimeters wide at the widest point. The system was configured so that thin wire electrodes were isolated inside of the optical fibers, thereby not allowing contact with the environment at the end of the device where the jet is produced. Such an electrode arrangement allows for great safety while also producing a stable plasma column and jet during treatment inside the patient's body. Despite the small inner diameter and the low gas flow rate, the generated plasma jets are shown to be stable and sufficiently effective at treating cells or germs. The exceptional flexibility and length of the micro-plasma device will enable it to reach diverse areas inside the human body. Plasma devices analogous to the one created have enormous potential for the treatment of a myriad of internal human ailments due to the devices' great flexibility and favorable chemical, medical, and physical properties.

  2. Development of a non-equilibrium 60 MHz plasma jet with a long discharge plume

    NASA Astrophysics Data System (ADS)

    Uchida, Giichiro; Kawabata, Kazufumi; Ito, Taiki; Takenaka, Kosuke; Setsuhara, Yuichi

    2017-07-01

    High-frequency plasma jets driven by voltages in the frequency range of 6-60 MHz are developed. A long plasma jet, 40 mm in length, is successfully produced by using a pair of ring electrodes outside a quartz tube. The electrode pair consists of a wide power electrode and a narrow ground electrode that is positioned at the head of the tube. The ratio of the length of the ground electrode to the length of the power electrode must be small in order to produce long plasma jets. The high-frequency plasma jet is operated in a non-thermal-equilibrium state at a gas temperature of around 60 °C. Operation at the very-high-frequency of 60 MHz leads to a lower discharge voltage and lower electron energy compared to lower frequencies of 6 and 13.56 MHz. The ability of the very-high-frequency (60 MHz) plasma jet to produce reactive oxygen and nitrogen species in water is also investigated. High H2O2 and NO3- concentrations of more than 1 mmol/l are realized by irradiating 3 ml of deionized water with the plasma for a short period of 2 min.

  3. 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.

  4. DNA strand scission induced by a non-thermal atmospheric pressure plasma jet.

    PubMed

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

    2010-07-28

    The DNA molecule is observed to be very susceptible to short-term exposures to an atmospheric pressure plasma jet. The DNA damage induced by plasma-generated species, i.e. excited atoms, charged particles, electrons and UV light is determined.

  5. Electronic ground state OH(X) radical in a low-temperature atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Fuh, Che A.; Clark, Shane M.; Wu, Wei; Wang, Chuji

    2016-10-01

    The wide applicability of atmospheric pressure plasma jets in biomedicine stems from the presence of reactive nitrogen and oxygen species generated in these plasma jets. Knowing the absolute concentration of these reactive species is of utmost importance as it is critical, along with the particle flux obtained from the plasma feed gas flow rate to ensure that the correct dosage is applied during applications. In this study, we investigate and report the ground state OH(X) number density acquired using cavity ringdown spectroscopy, along the propagation axis (z-axis) of a cold atmospheric pressure helium plasma plume. The jet was generated by a repetitively pulsed mono-polar square wave of duration 1 μs running at a frequency of 9.9 kHz. The voltage supplied was 6.5 kV with the helium flow rate fixed at 3.6 standard liters per minute. The rotational and vibrational temperatures are simulated from the second positive system of nitrogen, N 2(C3πu-B3πg) , with the rotational temperature being spatially constant at 300 K along the propagation axis of the atmospheric pressure plasma jet while the vibrational temperature is 3620 K at the beginning of the plume and is observed to decrease downstream. The OH(A) emission intensity obtained via optical emission spectroscopy was observed to decrease downstream of the plasma jet. The OH(X) number density along the propagation axis was initially 2.2 × 1013 molecules cm-3 before increasing to a peak value of 2.4 × 1013 molecules cm-3, from which the number density was observed to decrease to 2.2 × 1013 molecules cm-3 downstream of the plasma jet. The total OH(A, X) in the plasma jet remained relatively constant along the propagation axis of the plasma jet before falling off at the tip of the jet. The increase in vibrational temperature downstream and the simultaneous measurements of both the excited state OH(A) and the ground state OH(X) reported in this study provide insights into the formation and consumption of this

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  7. Electrons precipitation stimulated by plasma jets injection in FLUXUS and NORTH STAR active rocket experiments

    NASA Astrophysics Data System (ADS)

    Gavrilov, B.; Erlandson, R.; Lynch, K.; Meng, C.; Podgorny, I.; Pfaff, R.; Stenbaek-Nielsen, H.; Sobyanin, D.; Zetzer, J.

    In Russian-American active rocket experiments FLUXUS (49? N, 47? E, 1997) and NORTH STAR (70? N, 148? W, 1999) high-velocity plasma jets were injected along and across the geomagnetic field respectively. In the both experiments high- density plasma jets pushed out the magnetic field. Later, when the magnetic field penetrated into the plasma jet, plasma was polarized and E=-VxB/c electric field was registered. As a result, Alfvén waves, carrying the field-aligned currents, propagate along the magnetic field lines. If the current density is rather high, the field-aligned electric fields can appear, and electrons would be accelerated along the magnetic field lines. Electron fluxes with energy from several eV to 2 keV were revealed in the both experiments. During NORTH STAR experiment electron fluxes caused by auroral precipitation were also registered

  8. A low power miniaturized dielectric barrier discharge based atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Divya Deepak, G.; Joshi, N. K.; Pal, Dharmendra Kumar; Prakash, Ram

    2017-01-01

    In this paper, a dielectric barrier discharge plasma based atmospheric pressure plasma jet has been generated in a floating helix and floating end ring electrode configuration using argon and helium gases. This configuration is subjected to a range of supply frequencies (10-25 kHz) and supply voltages (2-6 kV) at a fixed rate of gas flow rate (i.e., 1 l/min). The electrical characterization of the plasma jet has been carried out using a high voltage probe and current transformer. The current-voltage characteristics have been analyzed, and the consumed power has been estimated at different applied combinations for optimum power consumption at maximum jet length. The obtained optimum power and jet length for argon and helium gases are 12 mW and 32 mm, and 7.7 mW and 42 mm, respectively. It is inferred that besides the electrode configurations, the discharge gas is also playing a significant role in the low power operation of the cold plasma jet at maximum jet length. The obtained results are interpreted on the basis of penning processes.

  9. Experimental Characterization of the Stagnation Layer between Two Obliquely Merging Supersonic Plasma Jets

    NASA Astrophysics Data System (ADS)

    Merritt, Elizabeth C.

    2013-10-01

    Experiments on the oblique merging of two supersonic argon plasma jets have been conducted at LANL in order to assess the use of such jets to form imploding spherical plasma liners for high energy density physics applications. The plasma jets are formed and launched by pulsed-power-driven railguns and have initial jet parameters of n ~ 2 ×1016 cm-3, Te ~ 1 . 4 eV, ionization fraction ~ 0 . 96 , velocity ~ 30 km/s, diameter = 5 cm, and length ~ 20 cm. We have experimentally identified density increases that are consistent with shock formation, and a few-cm thick stagnation layer structure observed both in CCD camera images and interferometer density profiles. Although the jets are each individually collisional, the mean free path between counter-streaming ions is on the same order as the stagnation layer thickness, placing the jet merging in a semi-collisional regime. It was not known a priori whether the observations corresponded to hydrodynamic oblique shocks and whether two-fluid or kinetic effects played a role. Through careful analysis of the stagnation layer density and emission profiles, and comparisons between the data and both analytic hydrodynamic shock theory and multi-fluid plasma simulations, we demonstrate that our observations are consistent with collisional shocks. Work performed in collaboration with colleagues from LANL, Univ. of New Mexico, HyperV Technologies, Univ. of Alabama in Huntsville, Voss Scientific, Prism Computational Sciences, and Tech-X; supported by DOE-OFES.

  10. A low power miniaturized dielectric barrier discharge based atmospheric pressure plasma jet.

    PubMed

    Divya Deepak, G; Joshi, N K; Pal, Dharmendra Kumar; Prakash, Ram

    2017-01-01

    In this paper, a dielectric barrier discharge plasma based atmospheric pressure plasma jet has been generated in a floating helix and floating end ring electrode configuration using argon and helium gases. This configuration is subjected to a range of supply frequencies (10-25 kHz) and supply voltages (2-6 kV) at a fixed rate of gas flow rate (i.e., 1 l/min). The electrical characterization of the plasma jet has been carried out using a high voltage probe and current transformer. The current-voltage characteristics have been analyzed, and the consumed power has been estimated at different applied combinations for optimum power consumption at maximum jet length. The obtained optimum power and jet length for argon and helium gases are 12 mW and 32 mm, and 7.7 mW and 42 mm, respectively. It is inferred that besides the electrode configurations, the discharge gas is also playing a significant role in the low power operation of the cold plasma jet at maximum jet length. The obtained results are interpreted on the basis of penning processes.

  11. 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}.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    NASA Technical Reports Server (NTRS)

    Brown, Clifford A.

    2011-01-01

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

  15. Phased-Array Study of Dual-Flow Jet Noise: Effect of Nozzles and Mixers

    NASA Technical Reports Server (NTRS)

    Soo Lee, Sang; Bridges, James

    2006-01-01

    A 16-microphone linear phased-array installed parallel to the jet axis and a 32-microphone azimuthal phased-array installed in the nozzle exit plane have been applied to identify the noise source distributions of nozzle exhaust systems with various internal mixers (lobed and axisymmetric) and nozzles (three different lengths). Measurements of velocity were also obtained using cross-stream stereo particle image velocimetry (PIV). Among the three nozzle lengths tested, the medium length nozzle was the quietest for all mixers at high frequency on the highest speed flow condition. Large differences in source strength distributions between nozzles and mixers occurred at or near the nozzle exit for this flow condition. The beamforming analyses from the azimuthal array for the 12-lobed mixer on the highest flow condition showed that the core flow and the lobe area were strong noise sources for the long and short nozzles. The 12 noisy spots associated with the lobe locations of the 12-lobed mixer with the long nozzle were very well detected for the frequencies 5 KHz and higher. Meanwhile, maps of the source strength of the axisymmetric splitter show that the outer shear layer was the most important noise source at most flow conditions. In general, there was a good correlation between the high turbulence regions from the PIV tests and the high noise source regions from the phased-array measurements.

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

    SciTech Connect

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

    2014-05-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

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

    PubMed

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

    2014-05-01

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

  19. Plasma Jet Motion Across the Geomagnetic Field in the ``North Star'' Active Geophysical Experiment

    NASA Astrophysics Data System (ADS)

    Gavrilov, B. G.; Zetzer, J. I.; Podgorny, I. M.; Sobyanin, D. B.; Meng, C.-I.; Erlandson, R. E.; Stenbaek-Nielsen, H. C.; Pfaff, R. F.; Lynch, K. A.

    2003-01-01

    The active geophysical rocket experiment ``North Star'' was carried out in the auroral ionosphere on January 22, 1999, at the Poker Flat Research Range (Alaska, USA) using the American research rocket Black Brant XII with explosive plasma generators on board. Separable modules with scientific equipment were located at distances of from 170 to 1595 m from the plasma source. The experiment continued the series of the Russian-American joint experiments started by the ``Fluxus'' experiment in 1997. Two injections of aluminum plasma across the magnetic field were conducted in the ``North Star'' experiment. They were different, since in the first injection a neutral gas cloud was formed in order to increase the plasma ionization due to the interaction of neutrals of the jet and cloud. The first and second injections were conducted at heights of 360 and 280 km, respectively. The measurements have shown that the charged particle density was two orders of magnitude higher in the experiment with the gas release. The magnetic field in the first injection was completely expelled by the dense plasma of the jet. The displacement of the magnetic field in the second injection was negligible. The plasma jet velocity in both injections decreased gradually due to its interaction with the geomagnetic field. One of the most interesting results of the experiment was the conservation of high plasma density during the propagation of the divergent jet to considerable distances. This fact can be explained by the action of the critical ionization velocity mechanism.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  2. Numerical study of the interaction of a helium atmospheric pressure plasma jet with a dielectric material

    NASA Astrophysics Data System (ADS)

    Wang, Lijun; Zheng, Yashuang; Jia, Shenli

    2016-10-01

    This is a computational modeling study of a cold atmospheric pressure helium plasma jet impinging on a dielectric surface placed normal to the jet axis. This study provides insights into the propagation mechanism of the plasma jet, the electrical properties, and the total accumulated charge density at the dielectric surface. For the radial streamer propagation along the dielectric surface, Penning ionization and the electron impact ionization of helium atoms are the major ionization reactions in the streamer head, while Penning ionization is the only dominant contributor along the streamer body. In addition, the plasma bullet velocity along the dielectric surface is 10-100 times lower than that in the plasma column. Increasing tube radius or helium flow rate lowers air entrainment in the plasma jet, leading to a decrease of the radial electric field and the accumulated charge density at the dielectric surface. Furthermore, the tube radius has weaker influence on the plasma properties as tube radius increases. For a target dielectric with lower relative permittivity, a higher radial electric field penetrates into the material, and the surface ionization wave along the dielectric surface extends farther. Higher relative permittivity of the treated dielectric results in more charging at the dielectric surface and more electron density in the plasma column.

  3. The impact of Hall physics on magnetized plasma jets produced by radial foil configurations

    NASA Astrophysics Data System (ADS)

    Gourdain, P.-A.; Greenly, J. B.; Hammer, D. A.; Kusse, B. R.; Schrafel, P. C.; Seyler, C. E.; Bland, S. N.; Hall, G. N.; Lebedev, S. V.; Suzuki-Vidal, F.

    2012-10-01

    Although no one argues that plasma resistivity is important to include in the astrophysical simulations, based upon experiments with magnetized jets on pulsed power machines in the laboratory, we believe it may also be important to include the Hall term in the generalized Ohm's law in astrophysics simulation codes. In this talk, experiments carried out at Cornell University and at Imperial College on 1 to 1.5 MA pulsed power generators feature a plasma disk and a collimated, axial plasma jet with large Re (10^5) and Rem (10^3). The plasma jet is generated by ablation from electrical currents, which flow in a thin aluminum foil and converge to a central multi-pin cathode located under the foil. A twist in the pins produce the axial magnetic field necessary to magnetized the jet. It was observed that changing the polarity of the current alters drastically the plasma dynamics, an indication of the importance of the Hall effect in plasmas produced by radial foils. The overall agreement between experimental results and numerical simulations indicates that PERSEUS accounts properly for Hall physics in this geometry and plasma parameter range. Scaling to astrophysical occurrences via numerical simulations should highlight how Hall physics affects the dynamics of larger accretion disks.

  4. Power compensators for phased operation of antenna arrays on JET and DIII-D

    SciTech Connect

    Goulding, R.H.; Hoffman, D.J.; Ryan, P.M. ); Bosia, G.; Bures, M.; Start, D.; Wade, T. ); Petty, C.C.; Pinsker, R.I. )

    1994-10-15

    A system has been designed to allow operation of the JET A2 antenna arrays with phasing between elements of other than 0 or [pi] at increased power. The system uses a hybrid coupler to transfer power in the direction opposite to that occurring at the antenna elements. This results in nearly equal currents and voltages on the feed lines and antenna structures, with nearly equal input powers at the rf generators. The direction and magnitude of the power transfer is controlled by adjustable tuning elements mounted on two of the four coupler ports. Much insight has been gained on optimization of the circuit design to maximize bandwidth ([similar to]10 MHz for the present JET design with 20 MHz a possibility) and power-handling capability. The concept has been tested initially on the DIII-D tokamak, with a compensator installed in the feed circuit for the four-element FWCD antenna array. In this application it acts to equalize input impedances, and will eventually be used to allow operation with multiple transmitters.

  5. Power compensators for phased operation of antenna arrays on JET and DIII-D

    SciTech Connect

    Goulding, R.H.; Hoffman, D.J.; Ryan, P.M.; Bosia, G.; Bures, M.; Start, D.; Wade, T.; Petty, C.C.; Pinsker, R.I.

    1993-06-01

    A system has been designed to allow operation of the JET A2 antenna arrays with phasing between elements of other than 0 or {pi} at increased power. The system uses a hybrid coupler to transfer power in the direction opposite to that occurring at the antenna elements. This results in nearly equal currents and voltages on the feed lines and antenna structures, with nearly equal input powers at the rf generators. The direction and magnitude of the power transfer is controlled by adjustable tuning elements mounted on two of the four coupler ports. Much insight has been gained on optimization of the circuit design to maximize bandwidth ({approximately}10 MHz for the present JET design with 20 MHz a possibility) and power-handling capability. The concept has been tested initially on the DIII-D tokamak, with a compensator installed in the feed circuit for the four-element FWCD antenna array. In this application it acts to equalize input impedances, and will eventually be used to allow operation with multiple transmitters.

  6. Power compensators for phased operation of antenna arrays on JET and DIII-D

    SciTech Connect

    Goulding, R.H.; Hoffman, D.J.; Ryan, P.M. ); Bosia, G.; Bures, M.; Start, D.; Wade, T. ); Petty, C.C.; Pinsker, R.I. )

    1993-01-01

    A system has been designed to allow operation of the JET A2 antenna arrays with phasing between elements of other than 0 or [pi] at increased power. The system uses a hybrid coupler to transfer power in the direction opposite to that occurring at the antenna elements. This results in nearly equal currents and voltages on the feed lines and antenna structures, with nearly equal input powers at the rf generators. The direction and magnitude of the power transfer is controlled by adjustable tuning elements mounted on two of the four coupler ports. Much insight has been gained on optimization of the circuit design to maximize bandwidth ([approximately]10 MHz for the present JET design with 20 MHz a possibility) and power-handling capability. The concept has been tested initially on the DIII-D tokamak, with a compensator installed in the feed circuit for the four-element FWCD antenna array. In this application it acts to equalize input impedances, and will eventually be used to allow operation with multiple transmitters.

  7. Study of an Atmospheric Pressure Plasma Jet of Argon Generated by Column Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Nur, M.; Kinandana, A. W.; Winarto, P.; Muhlisin, Z.; Nasrudin

    2016-11-01

    An atmospheric of argon plasma jet was generated by using column dielectric barrier discharge has been investigated. In this study, argon gas was passed through the capillary column by regulating the flow rate of gas. This atmospheric pressure plasma jet (APPJ) was generated by a sinusoidal AC high voltage in the range of 0.4 kV to 10 kV and at frequencies of 15 kHz and 26 kHz. APPJ has been produced with flow rate of argon gas from 1 litter/min - 10 litters/min. The electric current has been taken with variation of voltage and each interval argon gas flow rate of 1 litter/min. The results show that electric current increase linearly and then it trends to saturation condition by the increasing of applied voltage. We found also that the length of the plasma jet increase by augmenting of applied voltage both for frequencies of 15 kHz and 26 kHz. Furthermore, our results show that length of plasma jet optimum for flow rate of argon gas of 2 litters/minute. In addition, we obtained that the larger applied voltage, the greater the temperature of the plasma jet.

  8. Study of laser-created laboratory plasma jets with soft x-ray laser interferometry

    NASA Astrophysics Data System (ADS)

    Grava, Jonathan; Purvis, Michael; Filevich, Jorge; Marconi, Mario; Rocca, Jorge; Dunn, James; Moon, Stephen; Shlyaptsev, Vyacheslav

    2008-04-01

    Jet-like plasma structures were generated by irradiating V-shaped Al targets at I=1x10^12 W/cm^2 with 0.8 J Ti:Sa laser pulses of 120 ps duration. A narrow plasma plume was observed to expand from the bottom of the cavity with Mach number ˜ 5. The plasma jet evolution was studied using soft x-ray laser interferometry (λ= 46.9 nm), allowing electron density measurements of the 1-mm plasma that exceeded 1x10^20 cm-3. Late in the evolution the jet expands laterally and develops sidelobes as it interacts with additional material expanding from the walls. The measurements were compared with 2-D simulations from the code HYDRA to gain understanding of the mechanisms that form the narrow plasma jet, including the role of radiation cooling. Measurements of similar jets generated by irradiating targets of different Z are under way Work sponsored by NNSA-SSAA DOE Grant # DE-FG52-060NA26152 and the U.S. DOE LLNL through ILSA contract No. W-7405-Eng-48.

  9. The effect of plasma on solar cell array arc characteristics

    NASA Technical Reports Server (NTRS)

    Snyder, D. B.; Tyree, E.

    1984-01-01

    The influence from the ambient plasma on the arc characteristics of a negatively biased solar cell array was investigated. The arc characteristics examined were the peak current during an arc, the decay time as the arc terminates, and the charge lost during the arc. These arc characteristics were examined in a nitrogen plasma with charge densities ranging from 15,000 to 45,000 cu cm. Background gas pressures ranged from 8x1,000,000 to 6x100,000 torr. Over these ranges of parameters no significant effect on the arc characteristics were seen. Arc characteristics were also examined for three gas species: helium, nitrogen and argon. The helium arcs have higher peak currents and shorter decay times than nitrogen and argon arcs. There are slight differences in the arc characteristics between nitrogen and argon. These differences may be caused by the differences in mass of the respective species. Also, evidence is presented for an electron emission mechanism appearing as a precursor to solar array arcs. Occassionally the plasma generator could be turned off, and currents could still be detected in the vacuum system. When these currents are presented, arcs may occur.

  10. The effect of plasma on solar cell array arc characteristics

    NASA Technical Reports Server (NTRS)

    Snyder, D. B.; Tyree, E.

    1985-01-01

    The influence from the ambient plasma on the arc characteristics of a negatively biased solar cell array was investigated. The arc characteristics examined were the peak current during an arc, the decay time as the arc terminates, and the charge lost during the arc. These arc characteristics were examined in a nitrogen plasma with charge densities ranging from 15,000 to 45,000 cu cm. Background gas pressures ranged from 8x1,000,000 to 6x100,000 torr. Over these ranges of parameters no significant effect on the arc characteristics were seen. Arc characteristics were also examined for three gas species: helium, nitrogen and argon. The helium arcs have higher peak currents and shorter decay times than nitrogen and argon arcs. There are slight differences in the arc characteristics between nitrogen and argon. These differences may be caused by the differences in mass of the respective species. Also, evidence is presented for an electron emission mechanism appearing as a precursor to solar array arcs. Occasionally the plasma generator could be turned off, and currents could still be detected in the vacuum system. When these currents are presented, arcs may occur.

  11. Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL Karles Fellowship

    DTIC Science & Technology

    2015-11-30

    deposition), modify (e.g., chemical functionalization), and etch (in Si technology) materials. In low- pressure non-equilibrium discharge plasmas ...Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6750--15-9650 Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL... Plasma Physics Division i REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188 3. DATES COVERED (From - To) Standard Form 298 (Rev. 8-98

  12. Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL Karle’s Fellowship

    DTIC Science & Technology

    2015-11-30

    deposition), modify (e.g., chemical functionalization), and etch (in Si technology) materials. In low- pressure non-equilibrium discharge plasmas ...Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6750--15-9650 Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL... Plasma Physics Division i REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188 3. DATES COVERED (From - To) Standard Form 298 (Rev. 8-98

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  15. Electro-mechanical efficiency of plasma synthetic jet actuator driven by capacitive discharge

    NASA Astrophysics Data System (ADS)

    Zong, Haohua; Kotsonis, Marios

    2016-11-01

    A simplified model is established to estimate the jet exit density variation of a plasma synthetic jet actuator (PSJA) driven by a capacitive arc discharge. This model, in conjunction with phase-locked planar particle imaging velocimetry (PIV) measurements, enables the calculation of jet mechanical energy for different operating conditions. Discharge energy is directly calculated based on waveforms of applied voltage and discharge current. The ratio of jet mechanical energy to discharge energy provides the absolute electro-mechanical efficiency. Results indicate that PSJA is characterized by a rather low electro-mechanical efficiency in the order of 0.1%, while the maximum observed value under tested conditions is 0.22%. Electro-mechanical efficiency improves significantly with nondimensional energy deposition, and appears largely independent of jet exit diameter.

  16. Microbicidal activities of low frequency atmospheric pressure plasma jets on oral pathogens.

    PubMed

    Yamazaki, Hiromitsu; Ohshima, Tomoko; Tsubota, Yuji; Yamaguchi, Hiroyasu; Jayawardena, Jayanetti Asiri; Nishimura, Yasushi

    2011-01-01

    Research using low frequency atmospheric pressure plasma jets (LF jet) is becoming increasingly more common. We carried out experiments to evaluate the sterilizing effects of this technology on oral pathogenic microorganisms (S.mutans, C.albicans and E. faecalis) and to determine its potential for clinical application. We performed the direct exposure test on a solid surface, indirect exposure test on a liquid phase, and ROS (reactive oxygen species) inhibitory test. The results showed the LF jet had microbicidal effects on oral pathogens, and that the ROS influenced this sterilization effect. The experiments of this study revealed that LF jet had a sterilizing effect on oral pathogenic microorganisms present in both the solid and liquid phases. The sterilizing mechanism was considered to be related to the effect of superoxide anion radicals. These results indicate that LF jets may represent a novel technology that can be applied to the field of clinical dentistry.

  17. Decomposition of tetrodotoxin using multi-gas plasma jet.

    PubMed

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

    2014-04-01

    In this study, non-thermal multi-gas plasma treatments were performed for Tetrodotoxin (TTX) solution, and TTX decomposition was analyzed by liquid chromatography coupled with electrospray time-of-flight mass spectrometry. The TTX mass spectrum signal was reduced by plasma irradiations to different levels by using various gas species. Nitrogen plasma exhibited the optimal capability for TTX decomposition, followed by oxygen, argon, and carbon dioxide plasmas. The TTX concentration decreased 100-fold by nitrogen plasma treatment for 10 min.

  18. Nanosecond pulsed humid Ar plasma jet in air: shielding, discharge characteristics and atomic hydrogen production

    NASA Astrophysics Data System (ADS)

    Yatom, Shurik; Luo, Yuchen; Xiong, Qing; Bruggeman, Peter J.

    2017-10-01

    Gas phase non-equilibrium plasmas jets containing water vapor are of growing interest for many applications. In this manuscript, we report a detailed study of an atmospheric pressure nanosecond pulsed Ar  +  0.26% H2O plasma jet. The plasma jet operates in an atmospheric pressure air surrounding but is shielded with a coaxial argon flow to limit the air diffusion into the jet effluent core. The jet impinges on a metal plate electrode and produces a stable plasma filament (transient spark) between the needle electrode in the jet and the metal plate. The stable plasma filament is characterized by spatially and time resolved electrical and optical diagnostics. This includes Rayleigh scattering, Stark broadening of the hydrogen Balmer lines and two-photon absorption laser induced fluorescence (TaLIF) to obtain the gas temperature, the electron density and the atomic hydrogen density respectively. Electron densities and atomic hydrogen densities up to 5 × 1022 m-3 and 2 × 1022 m-3 have been measured. This shows that atomic hydrogen is one of the main species in high density Ar-H2O plasmas. The gas temperature does not exceed 550 K in the core of the plasma. To enable in situ calibration of the H TaLIF at atmospheric pressure a previously published O density calibration scheme is extended to include a correction for the line profiles by including overlap integrals as required by H TaLIF. The line width of H TaLIF, due to collision broadening has the same trend as the neutral density obtained by Rayleigh scattering. This suggests the possibility to use this technique to in situ probe neutral gas densities.

  19. Structure of backward facing step flow in low Reynolds number controlled by synthetic jet array with different injection velocities

    NASA Astrophysics Data System (ADS)

    Takano, Saneyuki

    2013-11-01

    This study presents detailed structure of separated flow downstream of a backward facing step affected by a non-uniform periodic disturbance along spanwise direction induced by synthetic jet array. The Reynolds number based on the step height ranged from 300 to 900. The frequency of the synthetic jet actuation was selected within the acceptance frequency range of separating shear layer. The periodic disturbance generates periodic transverse vortices whose size and shape change corresponding to the strength of the disturbance. The effect of different injection velocities in the synthetic jet array from those of adjacent jets on the transverse vortex structure and resulting reattachment process is discussed based on the wall shear stress measured by the Micro Flow Sensor (MFS) and flow visualization. Near wall behavior of the transverse vortex above the MFS was related to the sensor output. The results show that non-uniform injection velocity manipulated in the jet array induces difference in the distorted vortex structure and reattachment process in spanwise direction, which strongly depend on the Reynolds number and injection velocities of the synthetic jets.

  20. Destruction of α-synuclein based amyloid fibrils by a low temperature plasma jet

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

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

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

    SciTech Connect

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

    2010-10-04

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

  2. A pulse-modulated nonequilibrium atmospheric-pressure microwave argon plasma discharge preionized by a kilohertz excited plasma jet

    SciTech Connect

    Li Shouzhe; Xu Maochun; Zhang Xin; Zhang Jialiang

    2012-04-23

    A pulse-modulated nonequilibrium atmospheric-pressure microwave argon surface wave plasma is generated by means of a preionization discharge with a single-electrode plasma jet driven by a power supply of 50 kHz. It is found that the electron induced Saha-like balance dominates excitation process in the plasma discharge through the electron temperature varying with the microwave input power and the applied voltage of kilohertz power supply. The microwave pulse-modulating effect on nonequilibrium characteristics of dual-frequency exciting argon surface wave plasma is studied by spectroscopic measurement of the excitation temperature and gas temperature.

  3. Imaging of the Staphylococcus aureus Inactivation Process Induced by a Multigas Plasma Jet.

    PubMed

    Takamatsu, Toshihiro; Kawano, Hiroaki; Sasaki, Yota; Uehara, Kodai; Miyahara, Hidekazu; Matsumura, Yuriko; Iwasawa, Atsuo; Azuma, Takeshi; Okino, Akitoshi

    2016-12-01

    To identify mechanisms underlying the bacterial inactivation process by atmospheric nonthermal plasma using a unique plasma jet that can generate various gas plasmas, Staphylococcus aureus were irradiated with carbon dioxide plasma, which produces a large amount of singlet oxygens, and nitrogen plasma, which produces a large amount of OH radicals. And damaged areas of plasma-treated bacteria were observed by field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. As a result, bacteria were damaged by both gas plasmas, but the site of damage differed according to gas species. Therefore, it suggests that singlet oxygen generated by carbon dioxide plasma or other reactive species caused by singlet oxygen contributes to the damage of internal structures of bacteria through the cell wall and membrane, and OH radicals generated by nitrogen plasma or other reactive species derived from OH radicals contribute to damage of the cell wall and membrane.

  4. Observation of high temperature plasma in nickel wire array implosions

    NASA Astrophysics Data System (ADS)

    Deeney, C.; Nash, T.; LePell, P. D.; Childers, K.; Krishnan, M.

    1989-12-01

    Time- and space-resolved filtered pinhole photography and crystal X-ray spectroscopy have been used to diagnose K-shell emission from nickel wire array implosions on the DNA/Double-EAGLE 6TW generator. In this paper, results are presented which show electron beam induced Ni Kα emission prior to and during a rapid localized heating of the plasma and the formation of intense hot spots. The observation of hydrogen-like nickel lines from the hot spots is indicative of multi-keV electron temperatures.

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

    SciTech Connect

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

    2014-05-15

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

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

    PubMed

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

    2013-01-01

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

  7. Numerical simulation of a dual-source supersonic plasma jet expansion process: continuum approach

    NASA Astrophysics Data System (ADS)

    Pal, Subrata; Dey, Subhrajit; Miebach, Thomas

    2007-05-01

    Expanding thermal plasma (ETP) is a versatile technology for thin film deposition process with directional plasma flux and high deposition rates. This process involves expansion of supersonic plasma jets through a steep pressure ratio into a chamber maintained at near vacuum. Usually the plasma jets deviate from chemical and thermal equilibrium and the continuum approach is insufficient to describe the phenomena. In the current work, the continuum approach based Navier-Stokes equations have been implemented to study and understand the jet expansion process in a typical dual-arc plasma deposition reactor. The numerical predictions have been compared against in-house experimental data obtained by thermocouple measurements. For the range of back pressures (6-200 Pa) considered, it was observed that the jet core is supersonic and transitions to a subsonic zone downstream without the formation of any Mach disc for the prevalent operating parameters. Indications of thick and smeared barrel shocks were however observed in the computed flow-thermal fields. The modelled fluid was assumed to be a perfect gas with temperature dependent specific heats, thermal conductivity and viscosity coefficients, with constant Prandtl number of order unity. The radial spreads of the jets increase with increasing pressure ratio thus leading to enhanced interactions within reduced distances downstream of the nozzle exit. The jet core Mach number also increases, but moderately, with decreasing backpressure. It is concluded that within reasonable accuracy, continuum approach based calculations are able to capture most of the important phenomena involved in compressible, high-temperature, supersonic jet expansion processes which are essential in designing chambers relevant to the mentioned processes.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  9. Detailed measurements of local heat transfer coefficient and adiabatic wall temperature beneath an array of impinging jets

    SciTech Connect

    Van Treuren, K.W.; Wang, Z.; Ireland, P.T.; Jones, T.V. . Dept. of Engineering Science)

    1994-07-01

    A transient method of measuring the local heat transfer under an array of impinging jets has been developed. The use of a temperature-sensitive coating consisting of three encapsulated thermochromic liquid crystal materials has allowed the calculation of both the local adiabatic wall temperature and the local heat transfer coefficient over the complete surface of the target plate. The influence of the temperature of the plate through which the impingment gas flows on the target plate heat transfer has been quantified. Results are presented for a single in-line array configuration over a range of jet Reynolds numbers.

  10. Solar Array Sails: Possible Space Plasma Environmental Effects

    NASA Technical Reports Server (NTRS)

    Mackey, Willie R.

    2005-01-01

    An examination of the interactions between proposed "solar sail" propulsion systems with photovoltaic energy generation capabilities and the space plasma environments. Major areas of interactions ere: Acting from high voltage arrays, ram and wake effects, V and B current loops and EMI. Preliminary analysis indicates that arcing will be a major risk factor for voltages greater than 300V. Electron temperature enhancement in the wake will be produce noise that can be transmitted via the wake echo process. In addition, V and B induced potential will generate sheath voltages with potential tether like breakage effects in the thin film sails. Advocacy of further attention to these processes is emphasized so that plasma environmental mitigation will be instituted in photovoltaic sail design.

  11. Tunable plasma edge in Josephson junction loaded wire array metamaterial

    NASA Astrophysics Data System (ADS)

    Trepanier, Melissa; Zhang, Daimeng; Koshelets, V. P.; Anlage, Steven

    It is desirable to have a tunable negative permittivity medium that operates in the microwave domain. The effective plasma frequency of a JJ-loaded wire array can be tuned as a function of dc current and temperature in the low current limit. To demonstrate this effect we observe a change in transmission through a single layer of 8 superconducting Nb wires that spans a rectangular waveguide. A simple model that treats the wires as an artificial dielectric with a tunable effective permittivity shows good agreement with measured results for tuning of the plasma edge. In addition we have observed interesting behavior at higher current and rf input power. The dynamics are very rich, highly hysteretic, and nonlinear. This work is supported by the NSF-GOALI and OISE programs through Grant # ECCS-1158644, and CNAM.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

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

    SciTech Connect

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

    2005-06-27

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

  14. Non-equilibrium plasma jet induced thermo-acoustic resistivity imaging for higher contrast and resolution.

    PubMed

    Guo, Liang; Li, Linbo; Dong, Fanqing; Jiang, Wencong

    2017-08-25

    A thermo-acoustic imaging modality induced by non-equilibrium atmospheric pressure plasma jet is reported. A tiny plasma jet is generated by a fast-rising pulsed dielectric barrier discharge and applied to the surface of the biological tissues. The pulsed conductive current induced by the conductive plasma jet is injected into the biological tissues. The Joule heating inside the tissue stimulates the ultrasound signals effectively. The amplitude of the ultrasound is related to the resistivity of the biological tissues near the contact point and takes the maximum at the certain conductivity of the certain frequency. Accordingly the thermo-acoustic resistivity imaging modality of high contrast and resolution is demonstrated theoretically and experimentally.

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

    SciTech Connect

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

    2014-03-10

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

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

    SciTech Connect

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

    2014-06-15

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

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

    NASA Astrophysics Data System (ADS)

    Whalley, Richard D.; Walsh, James L.

    2016-08-01

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

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

    PubMed

    Whalley, Richard D; Walsh, James L

    2016-08-26

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

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

    PubMed Central

    Whalley, Richard D.; Walsh, James L.

    2016-01-01

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

  20. Analysis of Ar plasma jets induced by single and double dielectric barrier discharges at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Judée, F.; Merbahi, N.; Wattieaux, G.; Yousfi, M.

    2016-09-01

    The aim is the comparison of different plasma parameters of single and double dielectric barrier discharge plasma jet configurations (S-DBD and D-DBD) which are potentially usable in biomedical applications. Both configurations are studied in terms of electric field distribution, electrical discharge characteristics, plasma parameters (estimated by optical emission spectroscopy analysis), and hydrodynamics of the plasma jet for electrical parameters of power supplies corresponding to an applied voltage of 10 kV, pulse duration of 1 μs, frequency of 9.69 kHz, and Ar flow of 2 l/min. We observed that the D-DBD configuration requires half the electrical power one needs to provide in the S-DBD case to generate a plasma jet with similar characteristics: excitation temperature around 4700 K, electron density around 2.5 × 1014 cm-3, gas temperature of about 320 K, a relatively high atomic oxygen concentration reaching up to 1000 ppm, the presence of reactive oxygen and nitrogen species (nitric oxide, hydroxyl radical, and atomic oxygen), and an irradiance in the UV-C range of about 20 μW cm-2. Moreover, it has been observed that D-DBD plasma jet is more sensitive to short pulse durations, probably due to the charge accumulation over the dielectric barrier around the internal electrode. This results in a significantly longer plasma length in the D-DBD configuration than in the S-DBD one up to a critical flow rate (2.25 l/min) before the occurrence of turbulence in the D-DBD case. Conversely, ionization wave velocities are significantly higher in the S-DBD setup (3.35 × 105 m/s against 1.02 × 105 m/s for D-DBD), probably due to the higher electrostatic field close to the high voltage electrode in the S-DBD plasma jet.

  1. 3D Mapping of plasma effective areas via detection of cancer cell damage induced by atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    SciTech Connect

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

    2012-12-15

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

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

    PubMed

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

    2010-02-01

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

  4. Monte Carlo study of Quark Gluon Plasma using photon jet observables

    NASA Astrophysics Data System (ADS)

    Xing, Tian

    2016-09-01

    Relativistic heavy ion collisions create an exotic state of deconfined, nuclear matter called quark gluon plasma (QGP), providing an opportunity to study the strong interaction. In some particularly hard scattered events, a parton with high transverse momentum (pT) interacts with this medium before fragmenting into a spray of particles, called a jet. Jet properties of heavy ion collisions can be modified relative to expectations from pp collisions; this effect is called jet quenching. Measurement of the jet internal structure can provide information about this effect and about the medium itself. On the other hand, studying systems whose jets are recoiled against photons coming from an initial scattering offers a way to calibrate the momentum of the modified jet. Since photons do not carry color charge, they escape the QGP with their initial momentum intact. On this poster, results using the Monte Carlo event generators Pythia and JEWEL will be presented for fragmentation functions and jet suppression from photon-jet events, alongside experimental data from CMS and ATLAS at a center of mass energy of 2.76 TeV. Predictions are also presented for lead-lead collisions at a center of mass energy of 5.02 TeV.

  5. 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).

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  7. 3-D MHD modeling and stability analysis of jet and spheromak plasmas launched into a magnetized plasma

    NASA Astrophysics Data System (ADS)

    Fisher, Dustin; Zhang, Yue; Wallace, Ben; Gilmore, Mark; Manchester, Ward; Arge, C. Nick

    2016-10-01

    The Plasma Bubble Expansion Experiment (PBEX) at the University of New Mexico uses a coaxial plasma gun to launch jet and spheromak magnetic plasma configurations into the Helicon-Cathode (HelCat) plasma device. Plasma structures launched from the gun drag frozen-in magnetic flux into the background magnetic field of the chamber providing a rich set of dynamics to study magnetic turbulence, force-free magnetic spheromaks, and shocks. Preliminary modeling is presented using the highly-developed 3-D, MHD, BATS-R-US code developed at the University of Michigan. BATS-R-US employs an adaptive mesh refinement grid that enables the capture and resolution of shock structures and current sheets, and is particularly suited to model the parameter regime under investigation. CCD images and magnetic field data from the experiment suggest the stabilization of an m =1 kink mode trailing a plasma jet launched into a background magnetic field. Results from a linear stability code investigating the effect of shear-flow as a cause of this stabilization from magnetic tension forces on the jet will be presented. Initial analyses of a possible magnetic Rayleigh Taylor instability seen at the interface between launched spheromaks and their entraining background magnetic field will also be presented. Work supported by the Army Research Office Award No. W911NF1510480.

  8. Optical emission spectroscopy of deuterium and helium plasma jets emitted from plasma focus discharges at the PF-1000U facility

    NASA Astrophysics Data System (ADS)

    Skladnik-Sadowska, E.; Dan'ko, S. A.; Kwiatkowski, R.; Sadowski, M. J.; Zaloga, D. R.; Paduch, M.; Zielinska, E.; Kharrasov, A. M.; Krauz, V. I.

    2016-12-01

    Optical emission spectroscopy techniques were used to investigate the spectra of dense deuterium-plasma jets generated by high-current pulse discharges within the large PF-1000U facility and to estimate parameters of plasma inside the jets and their surroundings. Time-resolved optical spectra were recorded by means of a Mechelle®900 spectrometer. From an analysis of the deuterium line broadening, it was estimated that the electron concentration at a distance 57 cm from the electrode outlets amounted to (0.4-3.7) × 1017 cm-3 depending on the initial gas distribution and the time interval of the spectrum registration after the instant of the plasma jet generation. From the re-absorption dip in the Dβ profile, it was assessed that the electron concentration in the surrounding gas was equal to about 1.5 × 1015 cm-3. On the basis of the measured ratio of He II 468.6 nm and He I 587.6 nm line intensities, it was estimated that the electron temperature amounted to about 5.3 eV. Also estimated were some dimensionless parameters of the investigated plasma jets.

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

    PubMed

    Motrescu, Iuliana; Nagatsu, Masaaki

    2016-05-18

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

  10. Comparison of scrape-off layer transport in inner and outer wall limited JET plasmas

    NASA Astrophysics Data System (ADS)

    Silva, C.; Arnoux, G.; Devaux, S.; Frigione, D.; Groth, M.; Horacek, J.; Lomas, P. J.; Marsen, S.; Matthews, G.; Pitts, R. A.; JET-EFDA Contributors

    2013-07-01

    The JET scrape-off layer has been characterized with a reciprocating probe in inner wall, IW, and outer wall, OW, limited plasmas. Broad SOL profiles are observed for IW limited plasmas with power e-folding length substantially larger (by a factor of ˜5-7.5) than in OW limited plasmas. The properties of the fluctuations in the SOL parameters indicate larger turbulent transport for IW limited plasmas. The striking differences observed between IW and OW limited plasmas on the power e-folding length, parallel flow, turbulent transport as well as the characteristics of the fluctuations support the existence of a poloidally localized region of enhanced radial transport near the outboard midplane. The dependence of the SOL power e-folding length on the main plasma parameters was also investigated for IW limited plasmas and a modest negative dependence on both the plasma current and the line-averaged density found.

  11. Plasma Characteristics Measured in the Plume of a NEXT Multi-Thruster Array

    NASA Technical Reports Server (NTRS)

    Foster, John E.; Patterson, Michael; Pencil, Eric; McEwen, Heather; Diaz, Esther

    2006-01-01

    Plasma properties in the plume produced by a 3+1 NEXT thruster array operating at full power were mapped using a series of planar Langmuir probes. The Langmuir probes were swept across the diameters of each thruster as well as the centerline of the array at multiple downstream axial locations to produce a plasma map of the plume produced by the array. Such maps yielded the spatial distribution of the plasma density, the electron temperature and the plasma potential in the near field of the array. This spatial information provides insight into local plasma particle flow. Flow direction is particularly important from both an array lifetime and spacecraft-plume plasma interaction standpoint. The variation in the plume plasma parameters tended to vary in a manner consistent with both plume shape and overlap of adjacent plumes.

  12. Modelling for turbulent transport of nanoparticles growing around a thermal plasma jet

    NASA Astrophysics Data System (ADS)

    Shigeta, Masaya

    2015-09-01

    Modelling works for expressing the simultaneous processes of growth and transport of nanoparticles around a turbulent-like thermal plasma jet are presented. From the physical aspect, extending the previous model, a simple-but-consistent model which requires less computational costs is developed to describe the nanoparticles' birth and collective growth through homogeneous nucleation, heterogeneous condensation, and coagulation among themselves as well as transports by convection, diffusion, and thermophoresis. From the mathematical aspect, an original simulation code with higher accuracy is developed to express thermal plasma turbulence and to capture steep gradients in the spatial distribution of nanoparticles. As a base case, an argon thermal plasma jet is ejected at 1.5 slm from the nozzle, and iron vapor is supplied at 0.1 g/min with the plasma jet. The computation shows that the high-temperature plasma jet entrains the surrounding non-ionized gas because of Kelvin-Helmholtz instability at their interface. The instability waves grow up and then the interface rolls up to eddies. As the jet goes downstream, the eddies break to smaller ones, which lead to turbulence transition. This feature has also been reported in the experimental study. The iron vapor is transported with the plasma flow and simultaneously diffuses across the plasma's fringe where the vapor experiences the temperature decrease. As a result, the vapor changes its phase to nanoparticles through nucleation and condensation. The nanoparticles are also transported by convection and diffusion. The regions of large diameters coincide with those of low number densities of nanoparticles, because the size of nanoparticles increases through coagulation among themselves decreasing their own numbers.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  14. Ultraviolet-Visible Imagery and Spectra of the Fluxus-1 and -2 Artificial Plasma Jets

    NASA Astrophysics Data System (ADS)

    Erlandson, R. E.; Swaminathan, P. K.; Meng, C. I.; Stoyanov, B. J.; Zetzer, J. I.; Gavrilov, B. G.; Kiselev, Yu. N.; Romanovsky, Yu. A.

    1998-11-01

    Two active geophysical rocket experiments, known as Fluxus-1 and Fluxus-2, were conducted to study the interaction of artificial aluminum plasma jets with the ionosphere. The plasma jets were generated at night without the aid of solar illumination using specially designed shaped-charge generators. In this paper we present observations from the space-based ultraviolet and visible sensors on the Midcourse Space Experiment (MSX) satellite. Spectrographic imagers on MSX were used to acquire an ultraviolet and visible spectrum of the shaped-charge event and plasma jet evolution. The spectrum contained Al II (Al+) line emissions, Al I line emissions, continuum emissions due to AlO formed through reactions of Al dimers (Al)x with atomic oxygen, and atmospheric emissions associated with O I and O II. The atmospheric emission features persisted for a few seconds while the Al I and II features were observed during the first frame (0.5s). The plasma jet evolved into a long-lasting luminous plasma cloud that was observed for over 70s from MSX and 3 minutes on the ground. The source of this cloud is most likely emissions from HAlOH.

  15. [Comparative study on the gas temperature of a plasma jet at atmospheric pressure].

    PubMed

    Jia, Peng-Ying; Li, Xue-Chen; Yuan, Ning

    2011-08-01

    A plasma jet of a dielectric barrier discharge in coaxial electrode was used to produce jet plasma in flowing work gas (argon mixed with trace nitrogen) at atmospheric pressure. The relation between the plasma length and the gas flow rate was obtained by taking the images of the jet plasma. A high-resolution optical spectrometer was used to collect the optical emission spectrum. The emission spectra of the first negative band of N(2+) (B2 Sigma(u+)-->Chi2 Sigma(g+), 390-391.6 nm) were used to estimate the rotational temperature of the plasma plume by fitting the experimental spectra to the simulated spectra. The gas temperature was investigated by this optical method and results show that the gas temperature increases with increasing the applied voltage. For comparison, a thermometer was used to measure the temperature of the gas emitted from the jet. The results also show that the gas temperature increases with increasing the applied voltage. The gas temperatures obtained by the two methods are consistent. The difference was analyzed.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  17. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    NASA Astrophysics Data System (ADS)

    Pinchuk, M.; Stepanova, O.; Kurakina, N.; Spodobin, V.

    2017-05-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    PubMed

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

    2015-06-06

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

  20. Evaluation of the sensitivity of bacterial and yeast cells to cold atmospheric plasma jet treatments.

    PubMed

    Sharkey, Michael A; Chebbi, Ahmed; McDonnell, Kevin A; Staunton, Claire; Dowling, Denis P

    2015-06-07

    The focus of this research was first to determine the influence of the atmospheric plasma drive frequency on the generation of atomic oxygen species and its correlation with the reduction of bacterial load after treatment in vitro. The treatments were carried out using a helium-plasma jet source called PlasmaStream™. The susceptibility of multiple microbial cell lines was investigated in order to compare the response of gram-positive and gram-negative bacteria, as well as a yeast cell line to the atmospheric plasma treatment. It was observed for the source evaluated that at a frequency of 160 kHz, increased levels of oxygen-laden active species (i.e., OH, NO) were generated. At this frequency, the maximum level of bacterial inactivation in vitro was also achieved. Ex vivo studies (using freshly excised porcine skin as a human analog) were also carried out to verify the antibacterial effect of the plasma jet treatment at this optimal operational frequency and to investigate the effect of treatment duration on the reduction of bacterial load. The plasma jet treatment was found to yield a 4 log reduction in bacterial load after 6 min of treatment, with no observable adverse effects on the treatment surface. The gram-negative bacterial cell lines were found to be far more susceptible to the atmospheric plasma treatments than the gram-positive bacteria. Flow cytometric analysis of plasma treated bacterial cells (Escherichia coli) was conducted in order to attain a fundamental understanding of the mode of action of the treatment on bacteria at a cellular level. This study showed that after treatment with the plasma jet, E. coli cells progressed through the following steps of cell death; the inactivation of transport systems, followed by depolarization of the cytoplasmic membrane, and finally permeabilization of the cell wall.

  1. Cavity-enhanced absorption spectroscopy to characterize atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    van Helden, Jean-Pierre; Nave, Andy; Reuter, Stephan; Roepcke, Juergen; Gianella, Michele; Ritchie, Grant

    2016-09-01

    Non-equilibrium atmospheric pressure plasma jets gain more and more interest as their technological applications increase in diverse fields such as material processing and plasma medicine. Hence, it is essential to diagnose the fluxes of the species generated by these plasma sources to identify relevant fundamental processes and to improve process efficiency. Especially for a comprehensive understanding of the kinetics of the transient species involved, high precision measurements of reactive molecular precursors, free radicals and to identify of any short lived species are of crucial importance. However, the detection of transient species in these type of plasmas poses a challenge for diagnostic techniques as the plasmas typically have small dimensions and high density gradients in space and time. We have overcome these limitations by using cavity-enhanced absorption spectroscopy (CEAS). In this contribution, the latest results concerning the detection of transient species in two types of plasma jets employing CEAS in the near- and mid-infrared spectral range will be presented. We will show that with these methods spatially resolved investigations of concentrations in the mm sized effluent of the plasma jet can be achieved.

  2. Telescience operations with the solar array module plasma interaction experiment

    SciTech Connect

    Wald, L.W.; Bibyk, I.K.

    1995-09-01

    The Solar Array Module Plasma Interactions Experiment (SAMPIE) is a flight experiment that flew on the Space Shuttle Columbia (STS-62) in March 1994, as part of the OAST-2 mission. The overall objective of SAMPIE was to determine the adverse environmental interactions within the space plasma of low earth orbit (LEO) on modern solar cells and space power system materials which are artificially biased to high positive and negative direct current (DC) voltages. The two environmental interactions of interest included high voltage arcing from the samples to the space plasma and parasitic current losses. High voltage arcing can cause physical damage to power system materials and shorten expected hardware life. Parasitic current losses can reduce power system efficiency because electric currents generated in a power system drain into the surrounding plasma via parasitic resistance. The flight electronics included two programmable high voltage DC power supplies to bias the experiment samples, instruments to measure the surrounding plasma environment in the STS cargo bay, and the on-board data acquisition system (DAS). The DAS provided in-flight experiment control, data storage, and communications through the Goddard Space Flight Center (GSFC) Hitchhiker flight avionics to the GSFC Payload Operations Control Center (POCC). The DAS and the SAMPIE POCC computer systems were designed for telescience operations; this paper will focus on the experiences of the SAMPIE team regarding telescience development and operations from the GSFC POCC during STS-62. The SAMPIE conceptual development, hardware design, and system verification testing were accomplished at the NASA Lewis Research Center (LeRC). SAMPIE was developed under the In-Space Technology Experiment Program (IN-STEP), which sponsors NASA, industry, and university flight experiments designed to enable and enhance space flight technology.

  3. Telescience operations with the solar array module plasma interaction experiment

    NASA Technical Reports Server (NTRS)

    Wald, Lawrence W.; Bibyk, Irene K.

    1995-01-01

    The Solar Array Module Plasma Interactions Experiment (SAMPIE) is a flight experiment that flew on the Space Shuttle Columbia (STS-62) in March 1994, as part of the OAST-2 mission. The overall objective of SAMPIE was to determine the adverse environmental interactions within the space plasma of low earth orbit (LEO) on modern solar cells and space power system materials which are artificially biased to high positive and negative direct current (DC) voltages. The two environmental interactions of interest included high voltage arcing from the samples to the space plasma and parasitic current losses. High voltage arcing can cause physical damage to power system materials and shorten expected hardware life. parasitic current losses can reduce power system efficiency because electric currents generated in a power system drain into the surrounding plasma via parasitic resistance. The flight electronics included two programmable high voltage DC power supplies to bias the experiment samples, instruments to measure the surrounding plasma environment in the STS cargo bay, and the on-board data acquisition system (DAS). The DAS provided in-flight experiment control, data storage, and communications through the Goddard Space Flight Center (GSFC) Hitchhiker flight avionics to the GSFC Payload Operations Control Center (POCC). The DAS and the SAMPIE POCC computer systems were designed for telescience operations; this paper will focus on the experiences of the SAMPIE team regarding telescience development and operations from the GSFC POCC during STS-62. The SAMPIE conceptual development, hardware design, and system verification testing were accomplished at the NASA Lewis Research Center (LeRC). SAMPIE was developed under the In-Space Technology Experiment Program (IN-STEP), which sponsors NASA, industry, and university flight experiments designed to enable and enhance space flight technology. The IN-STEP Program is sponsored by the Office of Space Access and Technology (OSAT).

  4. Characterization of scrape-off layer transport in JET limiter plasmas

    NASA Astrophysics Data System (ADS)

    Silva, C.; Arnoux, G.; Devaux, S.; Frigione, D.; Groth, M.; Horacek, J.; Lomas, P. J.; Marsen, S.; Matthews, G.; Meneses, L.; Pitts, R. A.; Contributors, JET-EFDA

    2014-08-01

    The JET scrape-off layer (SOL) has been characterized with a reciprocating probe in inner wall (IW), and outer wall (OW), limited plasmas. Experiments revealed that SOL profiles are substantially broader (by a factor of ˜5-7.5 in the power e-folding length) for IW limited than in OW limited plasmas. Results are consistent with the larger radial turbulent transport found for IW limited plasmas. Major differences are observed between IW and OW limited plasmas on the density and electron temperature e-folding lengths, parallel flow, radial turbulent transport as well as on the temporal and spatial characteristics of the fluctuations. Experimental findings on JET suggest that the differences in the SOL characteristics for both configurations are due to a combination of a poloidal asymmetry in radial transport with a reduced cross-field transport across the last closed flux surface associated with the confinement improvement observed for OW limited plasmas. The dependence of the SOL power e-folding length on the main plasma parameters was also investigated for IW limited plasmas and a modest negative dependence on both the plasma current and the line-averaged density found. Finally, it is shown that the SOL radial transport and the amplitude of the fluctuations increase with plasma current and decrease with line-averaged density for IW limited plasmas.

  5. 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.

  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. Bullet-to-streamer transition on the liquid surface of a plasma jet in atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Yoon, S.-Y.; Kim, G.-H.; Kim, S.-J.; Bae, B.; Kim, N.-K.; Lee, H.; Bae, N.; Ryu, S.; Yoo, S. J.; Kim, S. B.

    2017-01-01

    This study investigated the transition of the plasma shape from a ring-shaped bullet to a pin-like streamer adjacent to the electrolyte surface in a kHz-driven helium atmospheric pressure plasma jet. The transition was observed by synchronized fast images, plasma propagation speed, time-resolved emission profile of Hβ, and spatially and temporally resolved helium metastable density. The transition height increased when electrolyte evaporation was enhanced. The plasma continued to discharge on the electrolyte surface even in the absence of metastable species, i.e., the discharge mechanism changed from Penning ionization between helium metastable and ambient nitrogen to electron collision on evaporated water.

  8. 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.

  9. Contactless steering of a plasma jet with a 3D magnetic nozzle

    NASA Astrophysics Data System (ADS)

    Merino, Mario; Ahedo, Eduardo

    2017-09-01

    A 3D, steerable magnetic nozzle (MN) is presented that enables contactless thrust vector control of a plasma jet without any moving parts. The concept represents a substantial simplification over current plasma thruster gimbaled platforms, and requires only a small modification in thrusters that already have a MN. The characteristics of the plasma expansion in the 3D magnetic field and the deflection performance of the device are characterized with a fully magnetized plasma model, suggesting that thrust deflections of 5° -10° are readily achievable.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  11. Design and Construction of a Fast Ion Loss Faraday Cup Array Diagnostic for JET

    SciTech Connect

    D.S. Darrow; S. Bauumel; F.E. Cecil; V. Kiptily; R. Ellis; L. Pedrick; A. Werner

    2004-04-26

    A thin foil Faraday cup array is being built to measure the loss of 3.5 MeV alpha particles and MeV ion cyclotron heating (ICH) tail ions on JET. It will consist of nine detectors spread over five different poloidal locations and three radial positions. They will measure the poloidal distribution and radial scrape off of the losses. The detectors will be comprised of four layers of thin (2.5 micron) Ni foil, giving some resolution of the lost particle energy distribution as different ranges of energies will stop in different layers of the detector. One detector will utilize eight thinner (1.0 micron) foils to obtain a better resolved energy distribution. These detectors will accept particles incident up to 45{sup o} from the normal to the foils.

  12. Acoustic investigation of wall jet over a backward-facing step using a microphone phased array

    NASA Astrophysics Data System (ADS)

    Perschke, Raimund F.; Ramachandran, Rakesh C.; Raman, Ganesh

    2015-02-01

    The acoustic properties of a wall jet over a hard-walled backward-facing step of aspect ratios 6, 3, 2, and 1.5 are studied using a 24-channel microphone phased array at Mach numbers up to M=0.6. The Reynolds number based on inflow velocity and step height assumes values from Reh = 3.0 ×104 to 7.2 ×105. Flow without and with side walls is considered. The experimental setup is open in the wall-normal direction and the expansion ratio is effectively 1. In case of flow through a duct, symmetry of the flow in the spanwise direction is lost downstream of separation at all but the largest aspect ratio as revealed by oil paint flow visualization. Hydrodynamic scattering of turbulence from the trailing edge of the step contributes significantly to the radiated sound. Reflection of acoustic waves from the bottom plate results in a modulation of power spectral densities. Acoustic source localization has been conducted using a 24-channel microphone phased array. Convective mean-flow effects on the apparent source origin have been assessed by placing a loudspeaker underneath a perforated flat plate and evaluating the displacement of the beamforming peak with inflow Mach number. Two source mechanisms are found near the step. One is due to interaction of the turbulent wall jet with the convex edge of the step. Free-stream turbulence sound is found to be peaked downstream of the step. Presence of the side walls increases free-stream sound. Results of the flow visualization are correlated with acoustic source maps. Trailing-edge sound and free-stream turbulence sound can be discriminated using source localization.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  14. Effect of Processing Parameters on Plasma Jet and In-flight Particles Characters in Supersonic Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Wei, Pei; Wei, Zhengying; Zhao, Guangxi; Bai, Y.; Tan, Chao

    2016-09-01

    In supersonic plasma spraying system (SAPS), heat transfer from arc plasma is characterized by several distinct features, such as transport of dissociation and ionization energy and of electrical charges in addition to mass transport. The thermodynamic and transport properties of plasma jet were influenced by several main parameters such as primary gas flow rate, the H2 vol.% and current intensity A. This paper first analyzes the effect of these parameters on the temperature and velocity of plasma jet theoretically. Further, the loading particles were melted and accelerated by plasma jet. Effects of several main parameters such as carrier gas flow rate, the H2 vol.%, the current intensity, the voltage and the spraying distance on temperature and velocity of in-flight particle were studied experimentally. The average maximum temperature and velocity of in-flight particle at any given parameters were systematically quantified. Optimal SAPS process parameters were given in this paper. In general, increasing the particles impacting velocity and surface temperature can improve the maximum spreading factor and decrease the coating porosity.

  15. Imaging gas and plasma interactions in the surface-chemical modification of polymers using micro-plasma jets

    NASA Astrophysics Data System (ADS)

    Oh, Jun-Seok; Olabanji, Olumuyiwa T.; Hale, Craig; Mariani, Raffaello; Kontis, Konstantinos; Bradley, James W.

    2011-04-01

    This paper reports on the correlation between gas flow and plasma behaviour in the outflow of a micro-atmospheric pressure plasma jet operating in helium using both 2D optical imaging and Schlieren photography. Schlieren photography shows that the helium outflow changes from laminar to turbulent conditions after distances between 20 and 50 mm from the nozzle. Above a flow rate of 1.4 slm, the length of the laminar region decreases with increasing flow rate. However, by contrast the visible plasma plume increases in length with increasing flow rate until its extension just exceeds that of the laminar region. At this point, the plasma becomes turbulent and its length decreases. Exposing polystyrene (PS) samples to the plasma jet significantly alters the water contact angle in a defined area, with the hydrophobic PS surface becoming more hydrophilic. This modification occurs both with and without direct contact of the visible glow on the surface. The radius of the treated area is much larger than the width of the visible jet but much smaller than the area of the turbulence on the surface. The treated area reduces with increasing nozzle-substrate distance.

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

    NASA Astrophysics Data System (ADS)

    Pogrebnyak, Alexander D.; Tyurin, Yu N.

    2005-05-01

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

  17. 3D Kinetic Simulation of Plasma Jet Penetration in Magnetic Field

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    A high velocity plasmoid penetration through a magnetic barrier is a problem of a great experimental and theoretical interest. Our LSP PIC code 3D fully kinetic numerical simulations of high density (10^16 cm-3) high velocity (30-140 km/sec) plasma jet/bullet, penetrating through the transversal magnetic field, demonstrate three different regimes: reflection by field, penetration by magnetic field expulsion and penetration by magnetic self-polarization. The behavior depends on plasma jet parameters and its composition: hydrogen, carbon (A=12) and C60-fullerene (A=720) plasmas were investigated. The 3D simulation of two plasmoid head-on injections along uniform magnetic field lines is analyzed. Mini rail plasma gun (accelerator) modeling is also presented and discussed.

  18. Comparative study between chemical and atmospheric pressure plasma jet cleaning on glass substrate

    NASA Astrophysics Data System (ADS)

    Elfa, Rizan Rizon; Ahmad, Mohd Khairul; Fhong, Soon Chin; Sahdan, Mohd Zainizan; Nayan, Nafarizal

    2017-01-01

    The atmospheric pressure plasma jet with low frequency and argon as working gas is presented in this paper to demonstrate its application for glass substrate clean and modification. The glass substrate clean by atmospheric pressure plasma jet is an efficient method to replace other substrate clean method. A comparative analysis is done in this paper between substrate cleaned by chemical and plasma treatment methods. Water contact angle reading is taken for a different method of substrate clean and period of treatment. Under the plasma treatment, the sample shows low surface adhesion due to having the surface property of super hydrophilic surface 7.26°. This comparative analysis is necessary in the industrial application for cost production due to sufficient time and method of substrate clean.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  20. Jets.

    PubMed

    Rhines, Peter B.

    1994-06-01

    This is a discussion of concentrated large-scale flows in planetary atmospheres and oceans, argued from the viewpoint of basic geophysical fluid dynamics. We give several elementary examples in which these flows form jets on rotating spheres. Jet formation occurs under a variety of circumstances: when flows driven by external stress have a rigid boundary which can balance the Coriolis force, and at which further concentration can be caused by the beta effect; when there are singular lines like the line of vanishing windstress or windstress-curl, or the Equator; when compact sources of momentum, heat or mass radiate jet-like beta plumes along latitude circles; when random external stirring of the fluid becomes organized by the beta effect into jets; when internal instability of the mass field generates zonal flow which then is concentrated into jets; when bottom topographic obstacles radiate jets, and when frontogenesis leads to shallow jet formation. Essential to the process of jet formation in stratified fluids is the baroclinic life cycle described in geostrophic turbulence studies; there, conversion from potential to kinetic energy generates eddy motions, and these convert to quasibarotropic motions which then radiate and induce jet-like large-scale circulation. Ideas of potential vorticity stirring by eddies generalize the notion of Rossby-wave radiation, showing how jets embedded in an ambient potential vorticity gradient (typically due to the spherical geometry of the rotating planet) gain eastward momentum while promoting broader, weaker westward circulation. Homogenization of potential vorticity is an important limit point, which many geophysical circulations achieve. This well-mixed state is found in subdomains of the terrestrial midlatitude oceans, the high-latitude circumpolar ocean, and episodically in the middle atmosphere. Homogenization expels potential vorticity gradients vertically to the top and bottom of the fluid, and sideways to the edges of

  1. Advances in physical study of high enthalpy plasma jets of technological interest: emission spectra and plasma characteristics

    NASA Astrophysics Data System (ADS)

    Belevtsev, A. A.; Chinnov, V. F.; Isakaev, E. Kh.; Markin, A. V.; Tazikova, T. F.; Tereshkin, S. A.

    1998-10-01

    Offers a comprehensive study of the emission spectra and plasma characteristics of high enthalpy atmospheric pressure argon and nitrogen jets produced by a high- current industrially important arc plasmatron with a vortex stabilized channel-anode (I<=3D500A, G=3D1-4g/s, jet diameter at a minimum-6mm). The spectra are taken at different distances from the cathode in the 200-950nm region with a spectral resolution=3D0.01nm allowing a fine structure of vibronic bands to be essentially resolved except that due to the dublet (spin) splitting and Λ-doubling. Also derived (through the Abel inversion) are radial distributions of plasma components. The spectra obtained have been used for determining plasma composition, the electron component parameters (by atomic/ionic Stark half-widths and intensities) and the assessment of rotational and vibrational temperatures by simulating molecular bands.

  2. Large-eddy simulations of plasma-based asymmetric control of supersonic round jets

    NASA Astrophysics Data System (ADS)

    González, D. R.; Gaitonde, D. V.; Lewis, M. J.

    2015-03-01

    Localised arc filament plasma actuators are modelled with a validated technique to examine asymmetric control of a perfectly expanded round free jet to deflect its downstream trajectory. The nominal Mach and Reynolds numbers are 1.3 and 1 million, respectively. No-control, symmetrically controlled, and under-expanded jets are also simulated for comparison purposes. Parametric variation of actuation frequency and duty cycle indicate that asymmetric control can alter the trajectory, and, within the confines of the parameters investigated, the optimal forcing scheme was found to correspond to the jet's column-mode frequency and a duty cycle of approximately 60%. Increasing frequency and duty cycle beyond these values have a detrimental effect on control, which is consistent with experimental findings. Asymmetric actuation resulted in significant mixing enhancement on the actuated side, as evidenced by the increased growth rate of the non-dimensional momentum thickness. The effectiveness of control is reduced for under-expanded jet conditions.

  3. Computer simulation of plasma electron collection by PIX-II. [solar array-space plasma interaction

    NASA Technical Reports Server (NTRS)

    Mandell, M. J.; Katz, I.; Jongeward, G. A.; Roche, J. C.

    1985-01-01

    A wake model was defined for the NASCAP/LEO finite element model for the plasma interaction experiment (PIX-II) launched to study the interaction between high-voltage large solar arrays with the space plasma environment. The cell surface model considers the individual cells, distances between interconnects, and the fraction of surface covered by interconnects. Account is taken of the electrostatic potential around the spacecraft, which travels at 7500 mps, over five times the speed of thermal ions. Ram ions are produced ahead of the array and the wake ion density is described with a geometric shadowing model. The model correctly predicted the currents in high and low bias voltages when compared to orbital data. The panel snapover, however, was projected to occur at 100 V and instead occurred at 300 V, which indicates that the snapover state is bistable. Finally, a low potential was both predicted and measured in the wake.

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

    NASA Astrophysics Data System (ADS)

    Gyulassy, Miklos

    2015-04-01

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

  5. Bactericidal effect of plasma jet with helium flowing through 3% hydrogen peroxide against Enterococcus faecalis

    PubMed Central

    Zhou, Xin-Cai; Li, Yu-Lan; Liu, De-Xi; Cao, Ying-Guang; Lu, Xin-Pei

    2016-01-01

    The aim of the present study was to assess the antimicrobial activity of plasma jet with helium (He) flowing through 3% hydrogen peroxide in root canals infected with Enterococcus faecalis. A total of 42 single-rooted anterior teeth were prepared, sterilized, inoculated with an E. faecalis suspension and incubated for 7 days. Next, the teeth were randomly divided into six experimental groups (including groups treated by plasma jet with or without He for different time durations) and one control group treated without plasma. The number of surviving bacteria in each canal was determined by counting the colony forming units (CFU)/ml on nutrient agar plates. The results indicated that statistically significant reduction in CFU/ml (P<0.005) existed for all treatment groups relative to the control group. The greatest reductions in CFU/ml were observed for Group 3 (7.027 log unit reduction) and Group 2 (6.237 log unit reduction), which were treated by plasma jet sterilization with He flowing through 3% hydrogen peroxide for 4 min or for 2 min, respectively. In addition, the reduction in Group 3 was significantly greater compared with that in Group 2 or in the groups treated by plasma jet sterilization without He flowing through 3% hydrogen peroxide for 1, 2 or 4 min. In conclusion, plasma jet with or without He flowing through 3% hydrogen peroxide can effectively sterilized root canals infected with E. faecalis and should be considered as an alternative method for root canal disinfection in endodontic treatments. PMID:27882119

  6. Analysis of Kelvin Helmholtz Instabilities of Plasma Jets

    NASA Technical Reports Server (NTRS)

    Friedman, Mark J.; Hollingsworth, Blane J.

    1999-01-01

    Ulysses data indicates density fluctuations which axe theorized to be the result of shear between a solar jet and its ambient. The MHD Kelvin-Helmholtz ("KH") instability causes such fluctuations as observed by Ulysses. A new dispersion relationship which accounts for this KH instability is derived via the linearization of the MHD equations. This generalizes an earlier result by Hardee. This dispersion relationship has the form of eight non-linear equations with nine unknowns.

  7. Analysis of Kelvin Helmholtz Instabilities of Plasma Jets

    NASA Technical Reports Server (NTRS)

    Friedman, Mark J.; Hollingsworth, Blane J.

    1999-01-01

    Ulysses data indicates density fluctuations which are theorized to be the result of shear between a solar jet and its ambient. The MHD Kelvin-Helmholtz ("KH") instability causes such fluctuations as observed by Ulysses. A new dispersion relationship which accounts for this KH instability is derived via the linearization of the MHD equations. This generalizes an earlier result by Hardee. This dispersion relationship has the form of eight non-linear equations with nine unknowns.

  8. Dense Plasma Jet Propagation for Endoatmospheric Ballistic Missile Defense

    DTIC Science & Technology

    1988-06-01

    control the arcjet mass flow rate. The modified arcjet source, in fact, appears to operate as an electrothermal vs electromagnetic arcjet . The jet flow...used to design improved diagnostic procedures and arcjet source characteristics for further experiments. I 20 OISTRIBUTION /AVAILABILITY OF AISTRACT 21...EXPERIMENTAL APPROACH 5 IV. EXPERIMENT DESIGN 9 V. INITIAL EXPERIMENTS 22 VI. EXPERIMENTS WITH MODIFIED ARCJET SOURCE 35 VII. SPECTROSCOPIC MEASUREMENTS

  9. Multiple jet impingement heat transfer characteristic: Experimental investigation of in-line and staggered arrays with crossflow

    NASA Technical Reports Server (NTRS)

    Florschuetz, L. W.; Metzger, D. E.; Takeuchi, D. I.; Berry, R. A.

    1980-01-01

    Heat transfer characteristics were obtained for configurations designed to model the impingement cooled midchord region of air cooled gas turbine airfoils. The configurations tested were inline and staggered two-dimensional arrays of circular jets with ten spanwise rows of holes. The cooling air was constrained to exit in the chordwise direction along the channel formed by the jet orifice plate and the heat transfer surface. Tests were run for chordwise jet hole spacings of five, ten, and fifteen hole diameters; spanwise spacings of four, six, and eight diameters; and channel heights of one, two, three, and six diameters. Mean jet Reynolds numbers ranged from 5000 to 50,000. The thermal boundary condition at the heat transfer test surface was isothermal. Tests were run for sets of geometrically similar configurations of different sizes. Mean and chordwise resolved Nusselt numbers were determined utilizing a specially constructed test surface which was segmented in the chordwise direction.

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

    PubMed

    Kim, Sun Ja; Chung, T H

    2016-02-03

    Cold atmospheric helium plasma jets were fabricated and utilized for plasma-cell interactions. The effect of operating parameters and jet design on the generation of specific reactive oxygen and nitrogen species (RONS) within cells and cellular response were investigated. It was found that plasma treatment induced the overproduction of RONS in various cancer cell lines selectively. The plasma under a relatively low applied voltage induced the detachment of cells, a reduction in cell viability, and apoptosis, while the plasma under higher applied voltage led to cellular necrosis in our case. To determine whether plasma-induced reactive oxygen species (ROS) generation occurs through interfering with mitochondria-related cellular response, we examined the plasma effects on ROS generation in both parental A549 cells and A549 ρ(0) cells. It was observed that cancer cells were more susceptible to plasma-induced RONS (especially nitric oxide (NO) and nitrogen dioxide (NO2(-)) radicals) than normal cells, and consequently, plasma induced apoptotic cell responses mainly in cancer cells.

  11. Formation of Jet Propulsion Near Dust Particle in Plasma

    SciTech Connect

    Vasilyak, L. M.; Vysykailo, F. I.; Fortov, V. E.; Molotkov, V. I.; Morfill, G. E.; Thomas, H. M.

    2011-11-29

    Processes of asymmetric ionization and cumulation of electric field and electron and ion flows can develop near the surface of charged dust particles in plasma. In the region of cumulation asymmetry on heating, the particle surface and ion momentum transfer arises; as a result, the dust particle moves in the plasma with high velocity.

  12. 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.

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

    SciTech Connect

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

    2014-03-14

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    Non-equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises various innovative applications. The influence of Penning effect on the formation, propagation, and other physical properties of the plasma bullets in APPJ remains a debatable topic. By using a 10 cm wide active electrode and a frequency of applied voltage down to 0.5 Hz, the Penning effect caused by preceding discharges can be excluded. It was found that the Penning effect originating in a preceding discharge helps build a conductive channel in the gas flow and provide seed electrons, thus the discharge can be maintained at a low voltage which in turn leads to a smaller propagation speed for the plasma bullet. Photographs from an intensified charge coupled device reveal that the annular structure of the plasma plume for He is irrelevant to the Penning ionization process arising from preceding discharges. By adding NH3 into Ar to introduce Penning effect, the originally filamentous discharge of Ar can display a rather extensive plasma plume in ambient as He. These results are helpful for the understanding of the behaviors of non-equilibrium APPJs generated under distinct conditions and for the design of plasma jet features, especially the spatial distribution and propagation speed, which are essential for application.

  15. Cold atmospheric plasma jet effects on V79-4 cells.

    PubMed

    Lupu, Andreea-Roxana; Georgescu, N

    2010-01-01

    The effects of cold plasmas are due to charged particles, reactive oxygen species (ROS), reactive nitrogen species (RNS), UV photons, and intense electric field. In order to obtain a more efficient action on mammalian cells (useful for cancer therapy), we used in our studies chemically activated cold plasma (He and O2 gas mixture). V79-4 cells were exposed to plasma jet for different time periods (30, 60, 90, 120 and 150s), using different combinations of helium and oxygen inputs (He:2.5l/min + 02:12.5ml/min; He:2.51/min + O2:25ml/min; He:2.51/min + O2:37.5 ml/min). Using MTT test we demonstrated that plasma jet induced cell viability decrease in all cases. The effect of chemically activated cold plasma--apoptosis or necrosis--depends on gas mixture and treatment period. Taking into account that ROS density in cell microenvironment is related to O2 percent in the gas mixture and treatment period, we can presume that cell death is due to ROS produced in plasma jet.

  16. 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.

  17. Ion beam and plasma jet based methods in ultra-precision optics manufacturing

    NASA Astrophysics Data System (ADS)

    Arnold, Th.; Boehm, G.; Paetzelt, H.; Pietag, F.

    2015-01-01

    Ion beam and plasma jet based techniques can be used in alternative machining processes for generating and finishing of ultra-precision optical surfaces. Since atomistic mechanisms are responsible for surface material modification, etching, and deposition, very high accuracy on the atomic level can be achieved. Various advanced techniques like pulse-width modulated ion beam figuring, sub-aperture reactive ion beam etching, or ion beam assisted structuring, planarization and smoothing technologies have been investigated aiming at precision on sub-nanometer height scale and lateral scales ranging over the full spatial wavelength range from nanometers to meters. Additionally, different atmospheric reactive plasma jet processes and plasma jet assisted process chains for generating, correction and smoothing of complex shaped optical surfaces like aspheres with large departures to best fit sphere or free forms exhibiting strong gradients have been developed in the last decade. In the paper an overview to the most recent trends of non-conventional ultra-precision optics processing is given and latest results of optics manufacturing are shown. Specific examples are given to demonstrate that form generation (e.g. for laser beam shaping optics) and surface finishing and polishing using atmospheric plasma jet tools are promising applications exhibiting advantages with respect to process efficiency and flexibility. Furthermore, the capabilities of ion beam surface figure correction using a new approach to control the tool function are demonstrated.

  18. Comparison of the characteristics of atmospheric pressure plasma jets using different working gases and applications to plasma-cancer cell interactions

    NASA Astrophysics Data System (ADS)

    Joh, Hea Min; Kim, Sun Ja; Chung, T. H.; Leem, S. H.

    2013-09-01

    Atmospheric pressure plasma jets employing nitrogen, helium, or argon gases driven by low-frequency (several tens of kilohertz) ac voltage and pulsed dc voltage were fabricated and characterized. The changes in discharge current, optical emission intensities from reactive radicals, gas temperature, and plume length of plasma jets with the control parameters were measured and compared. The control parameters include applied voltage, working gas, and gas flow rate. As an application to plasma-cancer cell interactions, the effects of atmospheric pressure plasma jet on the morphology and intracellular reactive oxygen species (ROS) level of human lung adenocarcinoma cell (A549) and human bladder cancer cell (EJ) were explored. The experimental results show that the plasma can effectively control the intracellular concentrations of ROS. Although there exist slight differences in the production of ROS, helium, argon, or nitrogen plasma jets are found to be useful in enhancing the intracellular ROS concentrations in cancer cells.

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

    SciTech Connect

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

    2007-08-15

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

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

    NASA Astrophysics Data System (ADS)

    Karakas, Erdinc

    2011-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  2. Convection-Diffusion Model for Atmospheric Pressure Plasma Jets: Obtaining Off-Axis Data from On-Axis Measurements

    NASA Astrophysics Data System (ADS)

    Schmidt-Bleker, Ansgar; Dünnbier, Mario; Winter, Jörn; Weltmann, Klaus-Dieter; Reuter, Stephan

    2012-10-01

    An analytical convection-diffusion model for atmospheric pressure plasma jets is presented. The model can be applied both for ambient air species diffusion and for heat transfer into a jets effluent. Using on-axis data from experiments as input, the model can be used to extrapolate the measured quantities to the complete domain for laminar flows and near-axis region for turbulent flows. The method is applied to experimental data obtained from molecular beam mass spectrometry as well as from a VUV absorption spectrometry method using the plasma jet itself as a VUV emitter. The measurements are conducted on a turbulent atmospheric pressure argon plasma jet with a protective gas nozzle, allowing for the creation of a shielding gas curtain around the plasma jets effluent. The results obtained from the hybrid analytical-experimental method are compared to computational fluid dynamics simulations.

  3. Jet array impingement with crossflow-correlation of streamwise resolved flow and heat transfer distributions

    NASA Technical Reports Server (NTRS)

    Florschuetz, L. W.; Metzger, D. E.; Truman, C. R.

    1981-01-01

    Correlations for heat transfer coefficients for jets of circular offices and impinging on a surface parallel to the jet orifice plate are presented. The air, following impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer (impingement) surface. The downstream jets are subjected to a crossflow originating from the upstream jets. Impingement surface heat transfer coefficients resolved to one streamwise jet orifice spacing, averaged across the channel span, are correlated with the associated individual spanwise orifice row jet and crossflow velocities, and with the geometric parameters.

  4. Atomic oxygen behavior at downstream of AC excited atmospheric pressure He plasma jet

    NASA Astrophysics Data System (ADS)

    Takeda, Keigo; Ishikawa, Kenji; Tanaka, Hiromasa; Sekine, Makoto; Hori, Masaru

    2016-09-01

    Applications of atmospheric pressure plasma jets (APPJ) have been investigated in the plasma medical fields such as cancer therapy, blood coagulation, etc. Reactive species generated by the plasma jet interacts with the biological surface. Therefore, the issue attracts much attentions to investigate the plasma effects on targets. In our group, a spot-size AC excited He APPJ have been used for the plasma medicine. From diagnostics of the APPJ using optical emission spectroscopy, the gas temperature and the electron density was estimated to be 299 K and 3.4 ×1015 cm-3. The AC excited He APPJ which affords high density plasma at room temperature is considered to be a powerful tool for the medical applications. In this study, by using vacuum ultraviolet absorption spectroscopy, the density of atomic oxygen on a floating copper as a target irradiated by the He APPJ was measured as a function of the distance between the plasma source and the copper wire. The measured density became a maximum value around 8 ×1013 cm-3 at 12 mm distance, and then decreased over the distance. It is considered that the behavior was due to the changes in the plasma density on the copper wire and influence of ambient air.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    PubMed Central

    Kim, Sun Ja; Chung, T. H.

    2016-01-01

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

  7. Effects of H2 on Ar plasma jet: From filamentary to diffuse discharge mode

    NASA Astrophysics Data System (ADS)

    Wu, S.; Lu, X.; Zou, D.; Pan, Y.

    2013-07-01

    Atmospheric-pressure plasma jets have recently attracted significant interest for its widespread applications in many fields from medicine to nanotechnology, yet the issue of the controlling the stability of Ar plasma jets remains a major challenge. In this paper, when 3% or more H2 is added to working gas Ar, it is found that the Ar plasma transits from filamentary mode to diffuse mode. In addition, the electric characteristics and the dynamics of the plasmas are studied. It is found that the peak current flowing through the ground electrode for the filament mode is about 0.5 A, which is much higher than 0.05 A for the diffuse mode. Furthermore, similar with those reported, 100 shots integrated photographs on dynamic of the diffuse discharge are taken, the photographs reveal that the plasma plume propagation appears like a "plasma bullet." On the other hand, a single shot photographs of the plasma in the diffuse mode show the "plasma bullet" is actually composed of several interacting streamers. Detailed analysis shows that the slow ionization is responsible for the generation of the filamentary-to-diffuse mode transition.

  8. Plasma Jet (V)UV-Radiation Impact on Biologically Relevant Liquids and Cell Suspension

    NASA Astrophysics Data System (ADS)

    Tresp, H.; Bussiahn, R.; Bundscherer, L.; Monden, A.; Hammer, M. U.; Masur, K.; Weltmann, K.-D.; Woedtke, Th. V.; Reuter, S.

    2014-10-01

    In this study the generation of radicals in plasma treated liquids has been investigated. To quantify the contribution of plasma vacuum ultraviolet (VUV) and ultraviolet (UV) radiation on the species investigated, three cases have been studied: UV of plasma jet only, UV and VUV of plasma jet combined, and the plasma effluent including all reactive components. The emitted VUV has been observed by optical emission spectroscopy and its effect on radical formation in liquids has been analyzed by electron spin resonance spectroscopy. Radicals have been determined in ultrapure water (dH2O), as well as in more complex, biorelevant solutions like phosphate buffered saline (PBS) solution, and two different cell culture media. Various compositions lead to different reactive species formation, e.g. in PBS superoxide anion and hydroxyl radicals have been detected, in cell suspension also glutathione thiyl radicals have been found. This study highlights that UV has no impact on radical generation, whereas VUV is relevant for producing radicals. VUV treatment of dH2O generates one third of the radical concentration produced by plasma-effluent treatment. It is relevant for plasma medicine because although plasma sources are operated in open air atmosphere, still VUV can lead to formation of biorelevant radicals. This work is funded by German Federal Ministry of Education a Research (BMBF) (Grant # 03Z2DN12+11).

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  10. TFTR/JET INTOR workshop on plasma transport tokamaks

    SciTech Connect

    Singer, C.E.

    1985-01-01

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

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

    PubMed

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

    2015-01-01

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

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

    SciTech Connect

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

    2015-09-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  14. Relativistic plasmas in AGN jets. From synchrotron radiation to γ-ray emission

    NASA Astrophysics Data System (ADS)

    La Mura, Giovanni; Busetto, Giovanni; Ciroi, Stefano; Rafanelli, Piero; Berton, Marco; Congiu, Enrico; Cracco, Valentina; Frezzato, Michele

    2017-02-01

    Relativistic jets of plasma are a key ingredient of many types of Active Galactic Nuclei (AGN). Today we know that AGNs are powered by the accretion of interstellar material into the gravitational field of a Super Massive Black Hole, and that this process can release as much power as an entire galaxy the size of the Milky Way, from a region that is comparable to the Solar System in size. Depending on the properties of the central energy source, a large fraction of this power can be involved in the acceleration of magnetized plasmas at relativistic speeds, to form large-scale jets. The presence of jets affects the spectrum of AGNs through the emission of synchrotron radiation and Inverse Compton scattering of low energy photons, thus leading to a prominent non-thermal spectrum, sometimes extending from radio frequencies all the way up to γ-ray energies. Here we review some characteristic processes of radiation emission in AGN jets, which lead to the emission of photons in the radio, optical, X-ray and γ-ray bands, and we present the results of a spectroscopic campaign of optical counterparts. We discuss our observations and their connection with γ-ray properties in a scenario that traces the role of relativistic jets in different classes of AGNs, detected in both the local and the remote Universe. Contribution to the Topical Issue "Physics of Ionized Gases (SPIG 2016)", edited by Goran Poparic, Bratislav Obradovic, Dragana Maric and Aleksandar Milosavljevic

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

    NASA Astrophysics Data System (ADS)

    Borissov, Alexei; Neukirch, Thomas; Threlfall, James

    2016-05-01

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

  16. Self-consistent two-dimensional modeling of cold atmospheric-pressure plasma jets/bullets

    NASA Astrophysics Data System (ADS)

    Breden, D.; Miki, K.; Raja, L. L.

    2012-06-01

    A computational modeling study of streamer propagation in a cold, atmospheric-pressure, helium jet in ambient air is presented. A self-consistent, multi-species, multi-temperature plasma model with detailed finite-rate chemistry and photoionization effects is used to provide fundamental insights into the structure and dynamics of the streamers. A parametric study of the streamer properties as a function of important discharge geometric and operating conditions is performed. The fluid mechanical mixing layer between the helium jet core and the ambient air is instrumental in guiding the propagation direction of the streamer and gives the plasma jet a visibly collimated appearance. The key chemical reactions which drive the streamer propagation are electron-impact ionization of helium neutral and nitrogen molecules. Photoionization plays a role in enhancing the propagation speed of the streamer, but is not necessary to sustain the streamer. The streamer yields a large radical concentration through chemical reactions in the streamer head and the body. The streamer propagation speed increases with reduced helium jet radius and increased helium-air mixing layer width. Impurities in the helium jet result in a significant increase in the discharge propagation speed within the tube through photoionization, but not after the streamer propagates into the open ambient region. It is also observed that thinner electrodes produce stronger electric-field concentrations that increase discharge propagation speeds within the tube but have a smaller influence on the discharge after it emerges out of the tube as a streamer.

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

    PubMed

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

    2011-12-01

    An apparatus for generating atmospheric pressure plasma (APP) jet was used to investigate the inactivation of Listeria monocytogenes on the surface of agar plates and slices of cooked chicken breast and ham. He, N₂ (both 7 L/min), and mixtures of each with O₂ (0.07 L/min) were used to produce the plasma jets. After treatment for 2 min with APP jets of He, He + O₂, N₂, or N₂ + O₂, the numbers of L. monocytogenes on agar plates were reduced by 0.87, 4.19, 4.26, and 7.59 log units, respectively. Similar treatments reduced the L. monocytogenes inoculated onto sliced chicken breast and ham by 1.37 to 4.73 and 1.94 to 6.52 log units, respectively, according to the input gas used with the N₂ + O₂ mixture being the most effective. Most APP jets reduced the numbers of aerobic bacteria on the meat surfaces to <10² CFU/g, and the numbers remained below that level of detection after storage at 10 °C for 7 days. The results indicate that APP jets are effective for the inactivation of L. monocytogenes on sliced meats and for prolonging the shelf-life of such foods. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

    A nonequilibrium Ar /O2 plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. The decimal reduction time (D values) of the Ar /O2 plasma jet at an exposure distance of 0.5-1.5cm ranges from 5 to 57s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

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

    SciTech Connect

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

    2007-09-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

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

    SciTech Connect

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

    2014-09-15

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

  2. Vacuum ultraviolet spectroscopic analysis of AC excited non-equilibrium atmospheric pressure Ar plasma jet

    NASA Astrophysics Data System (ADS)

    Takeda, Keigo; Ishikawa, Kenji; Tanaka, Hiromasa; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru

    2014-10-01

    Plasma biomedical treatments with atmospheric pressure plasma jets (APPJ) have attracted very much. In the treatments, reactive species and high energy photons emitted from APPJ are important factors to realize the performance. Vacuum ultraviolet (VUV) spectroscopy is one of useful techniques to measure quantitative behaviors of atomic radicals and high energy photons. In this study, an AC excited APPJ with Ar gas has been investigated by using the spectroscopy. The Ar APPJ was generated under open air condition, and VUV emission spectra was measured by using a VUV monochromator. The spectra of atomic species such as O (130.4 nm), N (120.0, 174.3 nm), and H (121.6 nm) were observed. The emission intensity of N atom (174.3 nm) in the plasma remote region exponentially decreased with increasing the distance from the plasma jet. The absorption coefficient was estimated to be 1.8 cm-1, over 20 mm distance from the plasma jet, the coefficient increase to 4.2 cm-1 which is almost same with value due to atmosphere. We will discuss behaviors of reactive species and high energy photons emitted from the AC excited Ar APPJ on the basis of the results measured by VUV spectroscopy.

  3. Bullet-shaped ionization front of plasma jet plumes driven by microwave pulses at atmospheric gas pressure

    NASA Astrophysics Data System (ADS)

    Chen, Zhaoquan; Xia, Guangqing; Zou, Changlin; Liu, Xiaodong; Feng, Deren; Li, Ping; Hu, Yelin; Stepanova, Olga; Kudryavtsev, A. A.

    2017-09-01

    Ionization waves (propagating bullet-shaped plasma) are always present in atmospheric-pressure plasma jets generated by a pulsed DC power supply or low-frequency voltages. Nevertheless, whether these ionization waves exist for pulsed microwave plasma jets remains unclear. In this paper, a coaxial transmission line resonator driven by microwave pulses is capable of generating atmospheric pressure plasma jet plumes. Depending on the discharges, these plasma jet plumes exhibit distinctive characteristics, such as bullet-shaped ionization fronts for argon plasma and ball-shaped for helium plasma. Fast images show argon plasma plumes generating several small branches but only one dominant ionization front travels more distance along the jet axis. Both ionization-wave images and electromagnetic simulation results indicate that the bullet-shaped ionization front forms a plasma jet plume immediately. The dominant ionization wave is resonantly excited by the local enhanced electric field, which originates from the local net charge of the streamer plus surface plasmon polariton located at the open end of the resonator.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

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

    PubMed

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

    2015-03-01

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

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

    SciTech Connect

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

    2015-09-15

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

  7. Electrical and optical properties of Ar/NH3 atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Chang, Zheng-Shi; Yao, Cong-Wei; Chen, Si-Le; Zhang, Guan-Jun

    2016-09-01

    Inspired by the Penning effect, we obtain a glow-like plasma jet by mixing ammonia (NH3) into argon (Ar) gas under atmospheric pressure. The basic electrical and optical properties of an atmospheric pressure plasma jet (APPJ) are investigated. It can be seen that the discharge mode transforms from filamentary to glow-like when a little ammonia is added into the pure argon. The electrical and optical analyses contribute to the explanation of this phenomenon. The discharge mode, power, and current density are analyzed to understand the electrical behavior of the APPJ. Meanwhile, the discharge images, APPJ's length, and the components of plasma are also obtained to express its optical characteristics. Finally, we diagnose several parameters, such as gas temperature, electron temperature, and density, as well as the density number of metastable argon atoms of Ar/NH3 APPJ to help judge the usability in its applications.

  8. Electrical and optical properties of Ar/NH{sub 3} atmospheric pressure plasma jet

    SciTech Connect

    Chang, Zheng-Shi E-mail: gjzhang@xjtu.edu.cn; Yao, Cong-Wei; Chen, Si-Le; Zhang, Guan-Jun E-mail: gjzhang@xjtu.edu.cn

    2016-09-15

    Inspired by the Penning effect, we obtain a glow-like plasma jet by mixing ammonia (NH{sub 3}) into argon (Ar) gas under atmospheric pressure. The basic electrical and optical properties of an atmospheric pressure plasma jet (APPJ) are investigated. It can be seen that the discharge mode transforms from filamentary to glow-like when a little ammonia is added into the pure argon. The electrical and optical analyses contribute to the explanation of this phenomenon. The discharge mode, power, and current density are analyzed to understand the electrical behavior of the APPJ. Meanwhile, the discharge images, APPJ's length, and the components of plasma are also obtained to express its optical characteristics. Finally, we diagnose several parameters, such as gas temperature, electron temperature, and density, as well as the density number of metastable argon atoms of Ar/NH{sub 3} APPJ to help judge the usability in its applications.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    SciTech Connect

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

    2013-06-10

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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