Science.gov

Sample records for microwave-heated atmospheric plasma

  1. Analysis of a microwave-heated planar propagating hydrogen plasma

    SciTech Connect

    Knecht, J.P.; Micci, M.M.

    1988-02-01

    The heating of a gas to high temperatures by absorption of microwave radiation has been proposed as a potential electrothermal rocket propulsion system. One possible mode of microwave energy absorption is by means of a planar plasma region propagating toward the source of the microwave radiation. Such a planar propagating plasma can be spatially stabilized by a gas stream flowing in the same direction as the microwave radiation with a velocity equal to the plasma propagation velocity. A one-dimensional analysis of the microwave-heated planar propagating plasma for hydrogen gas was developed to predict maximum gas temperatures and propagation velocities. The governing electromagnetic and energy equations were numerically integrated with temperature-dependent thermodynamic properties of equilibrium hydrogen. The propagation velocity eigenvalue was solved by means of an iterative technique. Temperature distribution in the gas, propagation velocities, and percent power absorbed, reflected and transmitted, were obtained as a function of incident microwave power at a frequency of 2.45 GHza for hydrogen gas pressures of 1 and 10 atm. 19 references.

  2. Microwave heating power distribution in electron-cyclotron resonance processing plasmas, experiment and theory

    SciTech Connect

    Douglass, S.R.; Eddy, C. Jr.; Lampe, M.; Joyce, G.; Slinker, S.; Weber, B.V.

    1995-12-31

    The authors are currently investigating the mechanisms of microwave power absorption in an ECR plasma. The microwave electric field is detected with an antenna at the end of a shielded co-ax cable, connected to a bolometer for power measurements. Initial measurements have been 1-D along the axis of the plasma chamber. Later, 3-D profiles will be made of the microwave heating power distribution. A comparison of the experimental results with the theoretical microwave absorption are presented. A ray tracing analysis of the propagating right hand wave are given, including both collisional and collisionless absorption. Mode conversion effects are studied to explain why most of the power is absorbed at the entry window, especially the L wave power.

  3. X-ray imaging studies of electron cyclotron microwave-heated plasmas in the Tandem Mirror Experiment-Upgrade

    SciTech Connect

    Failor, B.H.

    1986-02-01

    An x-ray pinhole camera designed to efficiently detect photons with energies between 5 and 250 keV was built to image bremsstrahlung emission from a microwave-heated hot electron plasma. This plasma is formed at one of the thermal barrier locations in the Tandem Experiment-Upgrade at Lawrence Livermore National Laboratory. The instrument consists of a lead aperture, an x-ray converter in the form of a sodium-activated cesium iodide scintillator, light intensifier electronics, and a recording medium that may either be high speed film or a CCD array. The nominal spatial and temporal resolutions are one part in 40 and 17 msec, respectively. The component requirements for optimum performance were determined both analytically and by computer simulation, and were verified experimentally. The details of these results are presented. The instrument has been used to measure x-ray emission from the TMX-U west end cell. Data acquired with the x-ray camera has allowed us to infer the temporal evolution of the mirror-trapped electron radial profile.

  4. Enhanced flow injection leaching of rocks by focused microwave heating with in-line monitoring of released elements by inductively coupled plasma mass spectrometry.

    PubMed

    Silva, Milithza; Kyser, Kurt; Beauchemin, Diane

    2007-02-19

    A focused microwave digestion system was used to heat a mini-column of sample of crushed rock (hematite) during its successive leaching by repeated 250-microL injections of water, HNO(3) 1%, 10% and 30% (v/v). The mini-column was connected to the nebulizer of an inductively coupled plasma mass spectrometry instrument, which allowed a continuous monitoring of the progressive release of elements by a given leaching reagent. Quantitation of the accessible fraction of Mg, V, Cr, Mn, Co, Ni, Cu, Zn, Mo, Sb and Pb was done by calibration using 250-microL injections of standard solutions prepared in the leaching reagent matrices. Total digestion of the sample residue was also done to verify mass balance. With the exception of Mg, V and Co, where the same total amount was released with or without microwave heating, an increased release resulted from focused microwave heating, by up to an order of magnitude. Furthermore, mass balance was verified for more elements using microwave heating, presumably because of a lower relative proportion of spectroscopic interference as a result of an increased release of analytes. Using microwave energy in general resulted in the dissolution of additional phases, as evidenced by significantly different (208)Pb/(206)Pb ratios as well as the increased release of elements with milder reagents. In fact, in the case of Pb, leaching with 30% HNO(3) was no longer necessary as all the Pb was released in the first three leaching reagents. Microwave heating could therefore be used advantageously in on-line leaching for exploration geochemistry and environmental monitoring. PMID:17386636

  5. Variable frequency microwave heating apparatus

    DOEpatents

    Bible, Don W.; Lauf, Robert J.; Johnson, Arvid C.; Thigpen, Larry T.

    1999-01-01

    A variable frequency microwave heating apparatus (10) designed to allow modulation of the frequency of the microwaves introduced into a multi-mode microwave cavity (34) for testing or other selected applications. The variable frequency microwave heating apparatus (10) includes a microwave signal generator (12) and a high-power microwave amplifier (20) or a high-power microwave oscillator (14). A power supply (22) is provided for operation of the high-power microwave oscillator (14) or microwave amplifier (20). A directional coupler (24) is provided for detecting the direction and amplitude of signals incident upon and reflected from the microwave cavity (34). A first power meter (30) is provided for measuring the power delivered to the microwave furnace (32). A second power meter (26) detects the magnitude of reflected power. Reflected power is dissipated in the reflected power load (28).

  6. Atmospheric Ball Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Wurden, C. J. V.; Wurden, G. A.

    2008-11-01

    Free-floating atmospheric pressure copper hydroxyl ball plasmas have been studied in air and helium atmospheres, using still and high speed photography (up to 20,000 fps), collimated photodiodes, and spectroscopy. A fine boundary layer between the greenish Cu-OH cloud, and the air, is orange in color. However, when the discharge is initiated into a helium atmosphere, the boundary layer is no longer visible, suggesting that the visible boundary was caused by interactions with oxygen. We have studied scaling of the 10-cm diameter ball plasmas with both the size of the water bucket, and the applied discharge voltage, over the range of 500-5000 volts. When looking at the initial spider-leg breakdown above the water surface, the ratio of H-alpha to H-beta lines suggests a temperature of ˜0.3 eV. This is also consistent with the presence of molecular lines of OH, and perhaps CuOH2 in the rising cloud. The cloud is affected by, but can penetrate through an aluminum window screen mesh.

  7. Microwave heating of ceramic composites

    NASA Astrophysics Data System (ADS)

    Pelesko, J. A.; Kriegsmann, G. A.

    2000-02-01

    The microwave heating of a ceramic composite is modelled and analysed. The composite consists of many small ceramic particles embedded in a ceramic cement. The composite is assumed to be well insulated, and each particle is assumed to be in imperfect thermal contact with the surrounding cement. Based on these two assumptions an asymptotic theory exploiting the small Biot number and small non-dimensional contact conductance is developed. Our asymptotic theory yields a set of nonlinear partial differential equations which govern the temperature in the composite. These are reduced to a set of coupled nonlinear ordinary differential equations in which the surface area of each particle enters as a parameter. Recent experiments with such composites have shown that the steady-state temperature of the composite is strongly dependent upon the radii of the embedded particles. Our model captures this effect. In fact, our analysis shows that the assumption of imperfect thermal contact between the particles and the ceramic cement is essential for this trend to be established.

  8. Modeling of microwave heating of particulate metals

    NASA Astrophysics Data System (ADS)

    Mishra, P.; Upadhyaya, A.; Sethi, G.

    2006-10-01

    Recent studies have shown that metal powder compacts can be heated to high temperatures using microwaves. While microwave heating of ceramics is well understood and modeled, there is still uncertainty about the exact mechanism and mode of microwave heating of particulate metals. The current study describes an approach for modeling the microwave heating of metal powder compacts using an electromagnetic-thermal model. The model predicts the variation in temperature with time during sintering. The effect of powder size, emissivity, and susceptor heating on the heating rate has also been assessed. These predictions have been validated by the experimental observations of the thermal profiles of Sn-, Cu-, and W-alloy compacts, using a 2.45 GHz multimode microwave furnace.

  9. Microwave heat treating of manufactured components

    DOEpatents

    Ripley, Edward B.

    2007-01-09

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases. The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  10. 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.

  11. Interaction of Atmospheric Plasma Vortices

    NASA Astrophysics Data System (ADS)

    Izhovkina, N. I.; Artekha, S. N.; Erokhin, N. S.; Mikhailovskaya, L. A.

    2016-06-01

    Atmospheric electric fields, connected with the ionization of particles and plasma processes, occur in the fields of pressure gradients of mosaic mesh topology. Atmospheric aerosol particles play a significant role in the vortex generation. The Coriolis force and the motion of charged particles in the geomagnetic field lead to gyrotropy of the atmosphere and ionosphere. Occurrence of plasma vortices is stochastically determined for such an inhomogeneous gyrotropic medium. The geomagnetic field influences the change of structures of inhomogeneous media in the process of excitation of plasma vortices and their interaction. If colliding vortices are centered on the one geomagnetic line, the merge of vortices and the generation of a joint powerful vortex are possible. If a collision of vortices with centers at different geomagnetic field lines occurs, then the emergence of areas of heating and jet streams and the generation of new vortices are possible.

  12. Interaction of Atmospheric Plasma Vortices

    NASA Astrophysics Data System (ADS)

    Izhovkina, N. I.; Artekha, S. N.; Erokhin, N. S.; Mikhailovskaya, L. A.

    2016-08-01

    Atmospheric electric fields, connected with the ionization of particles and plasma processes, occur in the fields of pressure gradients of mosaic mesh topology. Atmospheric aerosol particles play a significant role in the vortex generation. The Coriolis force and the motion of charged particles in the geomagnetic field lead to gyrotropy of the atmosphere and ionosphere. Occurrence of plasma vortices is stochastically determined for such an inhomogeneous gyrotropic medium. The geomagnetic field influences the change of structures of inhomogeneous media in the process of excitation of plasma vortices and their interaction. If colliding vortices are centered on the one geomagnetic line, the merge of vortices and the generation of a joint powerful vortex are possible. If a collision of vortices with centers at different geomagnetic field lines occurs, then the emergence of areas of heating and jet streams and the generation of new vortices are possible.

  13. Graphene oxide reduction by microwave heating

    NASA Astrophysics Data System (ADS)

    Longo, Angela; Carotenuto, Gianfranco

    2016-05-01

    The possibility to prepare thermal reduced graphene oxide (Tr-GO) colloidal suspensions by microwave heating of graphene oxide (GO) suspensions in N-methyl-2-pyrrolidone (NMP) has been investigated. According to transmission electron microscopy (TEM) and absorption and emission spectroscopy characterization, such a type of thermal reduction does not lead to graphene quantum dots formation because only mono-functional oxygen-containing groups are removed.

  14. Controlled Microwave Heating Accelerates Rolling Circle Amplification

    PubMed Central

    Yoshimura, Takeo; Suzuki, Takamasa; Mineki, Shigeru; Ohuchi, Shokichi

    2015-01-01

    Rolling circle amplification (RCA) generates single-stranded DNAs or RNA, and the diverse applications of this isothermal technique range from the sensitive detection of nucleic acids to analysis of single nucleotide polymorphisms. Microwave chemistry is widely applied to increase reaction rate as well as product yield and purity. The objectives of the present research were to apply microwave heating to RCA and indicate factors that contribute to the microwave selective heating effect. The microwave reaction temperature was strictly controlled using a microwave applicator optimized for enzymatic-scale reactions. Here, we showed that microwave-assisted RCA reactions catalyzed by either of the four thermostable DNA polymerases were accelerated over 4-folds compared with conventional RCA. Furthermore, the temperatures of the individual buffer components were specifically influenced by microwave heating. We concluded that microwave heating accelerated isothermal RCA of DNA because of the differential heating mechanisms of microwaves on the temperatures of reaction components, although the overall reaction temperatures were the same. PMID:26348227

  15. Plasma heating of Io's atmosphere

    NASA Technical Reports Server (NTRS)

    Pospieszalska, M. K.; Johnson, R. E.

    1992-01-01

    A Monte-Carlo, molecule-tracking program was constructed to describe the structure of Io's atmosphere in the region penetrated by ions from the plasma torus. This region is shown to exhibit high temperatures, consistent with corona observations, independent of whether significant UV heating also occurs. The atmospheric structure is determined near the exobase, which is the region responsible for the supply of the Io torus.

  16. Microwave heating of lunar materials. Appendix A

    NASA Technical Reports Server (NTRS)

    Meek, Thomas T.

    1992-01-01

    Microwave heating of nonmetallic inorganic material has been of interest for many years. Von Hippel in the late 1940's and early 1950's investigated how microwave radiation up to 10 GHz couples to various insulator materials. Perhaps the most work has been done by Wayne Tinga at the University of Edmonton. Most of the work to date has been done at the two frequency bands allowed in industrial use (0.915 GHz and 2.45 GHz). However some work has recently been carried out at 28 GHz and 60 GHz. Work done in this area at Los Alamos National Laboratory is discussed.

  17. 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.

  18. Effect of Microwave Heating on Phytosterol Oxidation.

    PubMed

    Leal-Castañeda, Everth Jimena; Inchingolo, Raffaella; Cardenia, Vladimiro; Hernandez-Becerra, Josafat Alberto; Romani, Santina; Rodriguez-Estrada, María Teresa; Galindo, Hugo Sergio García

    2015-06-10

    The oxidative stability of phytosterols during microwave heating was evaluated. Two different model systems (a solid film made with a phytosterol mixture (PSF) and a liquid mixture of phytosterols and triolein (1:100, PS + TAG (triacylglycerol))) were heated for 1.5, 3, 6, 12, 20, and 30 min at 1000 W. PS degraded faster when they were microwaved alone than in the presence of TAG, following a first-order kinetic model. Up to 6 min, no phytosterol oxidation products (POPs) were generated in both systems. At 12 min of heating, the POP content reached a higher level in PSF (90.96 μg/mg of phytosterols) than in PS + TAG (22.66 μg/mg of phytosterols), but after 30 min of treatment, the opposite trend was observed. 7-Keto derivates were the most abundant POPs in both systems. The extent of phytosterol degradation depends on both the heating time and the surrounding medium, which can impact the quality and safety of the food product destined to microwave heating/cooking. PMID:25973984

  19. Microwave diagnostics of atmospheric plasmas

    NASA Astrophysics Data System (ADS)

    Scott, David

    Plasma treatment of biological tissues has tremendous potential due to the wide range of applications. Most plasmas have gas temperatures which greatly exceed room temperature. These are often utilized in electro-surgery for cutting and coagulating tissue. Another type of plasma, referred to as cold atmospheric plasma, or CAP, is characterized by heavy particle temperatures which are at or near room temperature. Due to this lack of thermal effect, CAP may provide less invasive medical procedures. Additionally, CAP have been demonstrated to be effective at targeting cancer cells while minimizing damage to the surrounding tissue. A recently fabricated Microwave Electron Density Device (MEDD) utilizes microwave scattering on small atmospheric plasmas to determine the electron plasma density. The MEDD can be utilized on plasmas which range from a fraction of a millimeter to several centimeters at atmospheric pressure when traditional methods cannot be applied. Microwave interferometry fails due to the small size of the plasma relative to the microwave wavelength which leads to diffraction and negligible phase change; electrostatic probes introduce very strong perturbation and are associated with difficulties of application in strongly-collisional atmospheric conditions; and laser Thomson scattering is not sensitive enough to measure plasma densities less than 1012 cm-3. The first part of this dissertation provides an overview of two types of small atmospheric plasma objects namely CAPs and plasmas utilized in the electro-surgery. It then goes on to describe the fabrication, testing and calibration of the MEDD facility. The second part of this dissertation is focused on the application of the MEDD and other diagnostic techniques to both plasma objects. A series of plasma images that illustrate the temporal evolution of a discharge created by an argon electrosurgical device operating in the coagulation mode and its behavior was analyzed. The discharge of the argon

  20. Low Temperature Atmospheric Pressure Plasma Sterilization Shower

    NASA Astrophysics Data System (ADS)

    Gandhiraman, R. P.; Beeler, D.; Meyyappan, M.; Khare, B. N.

    2012-10-01

    Low-temperature atmospheric pressure plasma sterilization shower to address both forward and backward biological contamination issues is presented. The molecular effects of plasma exposure required to sterilize microorganisms is also analysed.

  1. Selection of biological indicator for validating microwave heating sterilization.

    PubMed

    Sasaki, K; Mori, Y; Honda, W; Miyake, Y

    1998-01-01

    For the purpose of selecting an appropriate biological indicator for evaluation of the effects of microwave heating sterilization, we examined aerobic bacterial spores to determine whether microwaves have non-thermal sterilization effects. After microwave irradiation on dry bacterial spores (three species), none of the bacterial spores were killed. The survival rate of the spores after microwave irradiation of spore suspensions (twelve species) was compared with that after heating by a conventional method. The order of heat resistance in the bacterial species was similar between the two heating methods. Bacillus stearothermophilus spores were the most heat-resistant. These results suggest that microwaves have no non-thermal sterilization effects on bacterial spores, the specific resistant spores to microwave heating, and microwave heating sterilization can be evaluated in the same way as for conventional heating sterilization. As a biological indicator for evaluation of overkill sterilization, B. stearothermophilus spores may be appropriate for microwave heating sterilization as well as steam sterilization. PMID:9610169

  2. Atmospheric Pressure Plasma Process And Applications

    SciTech Connect

    Peter C. Kong; Myrtle

    2006-09-01

    This paper provides a general discussion of atmospheric-pressure plasma generation, processes, and applications. There are two distinct categories of atmospheric-pressure plasmas: thermal and nonthermal. Thermal atmospheric-pressure plasmas include those produced in high intensity arcs, plasma torches, or in high intensity, high frequency discharges. Although nonthermal plasmas are at room temperatures, they are extremely effective in producing activated species, e.g., free radicals and excited state atoms. Thus, both thermal and nonthermal atmosphericpressure plasmas are finding applications in a wide variety of industrial processes, e.g. waste destruction, material recovery, extractive metallurgy, powder synthesis, and energy conversion. A brief discussion of recent plasma technology research and development activities at the Idaho National Laboratory is included.

  3. Propagation of an atmospheric pressure plasma plume

    SciTech Connect

    Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y.

    2009-02-15

    The ''plasma bullet'' behavior of atmospheric pressure plasma plumes has recently attracted significant interest. In this paper, a specially designed plasma jet device is used to study this phenomenon. It is found that a helium primary plasma can propagate through the wall of a dielectric tube and keep propagating inside the dielectric tube (secondary plasma). High-speed photographs show that the primary plasma disappears before the secondary plasma starts to propagate. Both plumes propagate at a hypersonic speed. Detailed studies on the dynamics of the plasma plumes show that the local electric field induced by the charges on the surface of the dielectric tube plays an important role in the ignition of the secondary plasma. This indicates that the propagation of the plasma plumes may be attributed to the local electric field induced by the charges in the bulletlike plasma volume.

  4. Nanoparticle heating in atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Kramer, Nicolaas; Aydil, Eray; Kortshagen, Uwe

    2015-09-01

    The plasma environment offers a number of attractive properties that allow for the generation of nanoparticle materials that are otherwise hard to produce by other means. Among these are the generally high temperatures that nanoparticles can attain within plasmas, enabling the generation of nanocrystals of high melting point materials. In low pressure discharges, these high temperatures are the result of energetic surface reactions that strongly heat the small nanoparticles combined with the relatively slow heat transfer to the neutral gas. At atmospheric pressure, the nanoparticle intrinsic temperature is much more closely coupled to the neutral gas temperature. We study the heating of nanoparticles in atmospheric pressure plasmas based on a Monte Carlo simulation that takes into account the most important plasma-surface reactions as well as the conductive cooling of nanoparticles through the neutral gas. We find that, compared to low pressure plasmas, significantly higher plasma densities and densities of reactive species are required in order to achieve nanoparticle temperatures comparable to those in low pressure plasmas. These findings have important implications for the application of atmospheric pressure plasmas for the synthesis of nanoparticle materials. This work was supported by the DOE Plasma Science Center for Predictive Control of Plasma Kinetics.

  5. Modeling atmospheric pressure plasmas for biomedical applications

    NASA Astrophysics Data System (ADS)

    Graves, David

    2007-10-01

    The use of cold, atmospheric pressure plasmas for biomedical treatments is an exciting new application in gaseous electronics. Investigations to date include various tissue treatments and surgery, bacterial destruction, and the promotion of wound healing, among others. In this talk, I will present results from modeling the `plasma needle,' an atmospheric pressure plasma configuration that has been explored by several groups around the world. The biomedical efficacy of the plasma needle has been demonstrated but the mechanisms of cell and tissue modification or bacterial destruction are only just being established. One motivation for developing models is to help interpret experiments and evaluate postulated mechanisms. The model reveals important elements of the plasma needle sustaining mechanisms and operating modes. However, the extraordinary complexity of plasma-tissue interactions represents a long-term challenge for this burgeoning field.

  6. Research on atmospheric pressure plasma processing sewage

    NASA Astrophysics Data System (ADS)

    Song, Gui-cai; Na, Yan-xiang; Dong, Xiao-long; Sun, Xiao-liang

    2013-08-01

    The water pollution has become more and more serious with the industrial progress and social development, so it become a worldwide leading environmental management problem to human survival and personal health, therefore, countries are looking for the best solution. Generally speaking, in this paper the work has the following main achievements and innovation: (1) Developed a new plasma device--Plasma Water Bed. (2) At atmospheric pressure condition, use oxygen, nitrogen, argon and helium as work gas respectively, use fiber spectrometer to atmospheric pressure plasma discharge the emission spectrum of measurement, due to the different work gas producing active particle is different, so can understand discharge, different particle activity, in the treatment of wastewater, has the different degradation effects. (3) Methyl violet solution treatment by plasma water bed. Using plasma drafting make active particles and waste leachate role, observe the decolorization, measurement of ammonia nitrogen removal.

  7. Apparatus for microwave heat treatment of manufactured components

    DOEpatents

    Ripley, Edward B.

    2008-04-15

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases. The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  8. Methods for microwave heat treatment of manufactured components

    DOEpatents

    Ripley, Edward B.

    2010-08-03

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases. The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  9. Multiphysics modeling of microwave heating of whole tomato

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A mathematical model of a food is useful for prediction of temperature profiles during microwave heating. However, due to their complex geometry and interaction with electromagnetic fields, whole tomatoes resist an analytical approach to modeling the fruit as it is subjected to microwave energy. T...

  10. 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.

  11. Sterilization effects of atmospheric cold plasma brush

    SciTech Connect

    Yu, Q.S.; Huang, C.; Hsieh, F.-H.; Huff, H.; Duan Yixiang

    2006-01-02

    This study investigated the sterilization effects of a brush-shaped plasma created at one atmospheric pressure. A population of 1.0x10{sup 4}-1.0x10{sup 5} Escherichia coli or Micrococcus luteus bacteria was seeded in filter paper media and then subjected to Ar and/or Ar+O{sub 2} plasmas. A complete kill of the Micrococcus luteus required about 3 min argon plasma exposures. With oxygen addition into the argon plasma gas streams, a complete kill of the bacteria needed only less than 1 min plasma exposure for Micrococcus luteus and about 2 min exposure for Escherichia coli. The plasma treatment effects on the different bacteria cell structures were examined using scanning electron microscopy.

  12. Sterilization effects of atmospheric cold plasma brush

    NASA Astrophysics Data System (ADS)

    Yu, Q. S.; Huang, C.; Hsieh, F.-H.; Huff, H.; Duan, Yixiang

    2006-01-01

    This study investigated the sterilization effects of a brush-shaped plasma created at one atmospheric pressure. A population of 1.0×104-1.0×105 Escherichia coli or Micrococcus luteus bacteria was seeded in filter paper media and then subjected to Ar and/or Ar +O2 plasmas. A complete kill of the Micrococcus luteus required about 3 min argon plasma exposures. With oxygen addition into the argon plasma gas streams, a complete kill of the bacteria needed only less than 1 min plasma exposure for Micrococcus luteus and about 2 min exposure for Escherichia coli. The plasma treatment effects on the different bacteria cell structures were examined using scanning electron microscopy.

  13. Cold plasma brush generated at atmospheric pressure

    SciTech Connect

    Duan Yixiang; Huang, C.; Yu, Q. S.

    2007-01-15

    A cold plasma brush is generated at atmospheric pressure with low power consumption in the level of several watts (as low as 4 W) up to tens of watts (up to 45 W). The plasma can be ignited and sustained in both continuous and pulsed modes with different plasma gases such as argon or helium, but argon was selected as a primary gas for use in this work. The brush-shaped plasma is formed and extended outside of the discharge chamber with typical dimension of 10-15 mm in width and less than 1.0 mm in thickness, which are adjustable by changing the discharge chamber design and operating conditions. The brush-shaped plasma provides some unique features and distinct nonequilibrium plasma characteristics. Temperature measurements using a thermocouple thermometer showed that the gas phase temperatures of the plasma brush are close to room temperature (as low as 42 deg. C) when running with a relatively high gas flow rate of about 3500 ml/min. For an argon plasma brush, the operating voltage from less than 500 V to about 2500 V was tested, with an argon gas flow rate varied from less than 1000 to 3500 ml/min. The cold plasma brush can most efficiently use the discharge power as well as the plasma gas for material and surface treatment. The very low power consumption of such an atmospheric argon plasma brush provides many unique advantages in practical applications including battery-powered operation and use in large-scale applications. Several polymer film samples were tested for surface treatment with the newly developed device, and successful changes of the wettability property from hydrophobic to hydrophilic were achieved within a few seconds.

  14. Cold atmospheric plasma in cancer therapy

    SciTech Connect

    Keidar, Michael; Shashurin, Alex; Volotskova, Olga; Ann Stepp, Mary; Srinivasan, Priya; Sandler, Anthony; Trink, Barry

    2013-05-15

    Recent progress in atmospheric plasmas has led to the creation of cold plasmas with ion temperature close to room temperature. This paper outlines recent progress in understanding of cold plasma physics as well as application of cold atmospheric plasma (CAP) in cancer therapy. Varieties of novel plasma diagnostic techniques were developed recently in a quest to understand physics of CAP. It was established that the streamer head charge is about 10{sup 8} electrons, the electrical field in the head vicinity is about 10{sup 7} V/m, and the electron density of the streamer column is about 10{sup 19} m{sup −3}. Both in-vitro and in-vivo studies of CAP action on cancer were performed. It was shown that the cold plasma application selectively eradicates cancer cells in-vitro without damaging normal cells and significantly reduces tumor size in-vivo. Studies indicate that the mechanism of action of cold plasma on cancer cells is related to generation of reactive oxygen species with possible induction of the apoptosis pathway. It is also shown that the cancer cells are more susceptible to the effects of CAP because a greater percentage of cells are in the S phase of the cell cycle.

  15. Lunar atmosphere plasma and fields --Abstract only

    NASA Astrophysics Data System (ADS)

    Manka, R. H.; Freeman, J. W.; Michel, F. C.; Elphic, R. C.; McComas, D. J.; Hodges, R. R.; Burch, J. L.; Johnson, R. E.

    1994-06-01

    The lunar atmosphere, ionosphere, plasma, and fields form a complex, interactive system with the surface and interior. The Moon is exposed to solar wind plasma and electric and magnetic fields, as well as the Earth's magnetotail where it may encounter rapidly moving plasmoids. The lunar atmosphere is intimately coupled to the lunar surface and interior. Sources of the lunar atmosphere include venting of the interior (e.g. Ar-40) as well as lunar surface elements released into the atmosphere by solar wind and magnetospheric sputtering and by micrometeorites. In addition to the solar wind electric field, electric fields exist at the lunar surface due to a balance between local charging mechanisms. For the Moon in the solar wind, resulting electric potentials are expected to range from +5 to +10 volts on the dayside to -10's to -100's of volts on the nightside. Ions formed in the atmosphere or at the surface are accelerated by the surface electric fields and solar wind electric and magnetic fields. We show that the result is a strong flux of atmospheric and sputtered ions that readily can be detected by an ion spectrometer in lunar orbit or on the surface, giving comprehensive information about the atmospheric and surface composition.

  16. Three Modes of Air Atmospheric Pressure Plasma

    NASA Astrophysics Data System (ADS)

    Mohamed, Abdel-Aleam H.

    2015-09-01

    Atmospheric pressure plasma jet operating in air have gained a high interest due to its various applications in industry and biomedical. The presented air plasma jet system is consisted of stainless steel hollow needle electrode of 1 mm inner diameter which is covered with a quartz tube with a 1 mm diameter side hole. The hole is above the tube nozzle by 5 mm and it is covered by a copper ring which is connected to the ground. The needle is connected to sinusoidal 27 kHz high voltage power supply (25 kV) though a current limiting resistor of 50 k Ω. The tested distance between the needle tip and the side hole was 1 mm or 2.1 mm gape. The electric and plasma jet formation characteristics show three modes of operations. Through these modes the plasma length changes with air flow rate to increase in the first mode and to confine inside the quartz tube in the second mode, then it start to eject from the nozzle again and increase with flow rate to reach a maximum length of 7 mm at 4.5 SLM air flow rate in the third mode. The measured gas temperature of the plasma jet can approach room temperature (300 K). Moreover, the plasma jet emission spectra shows the presence of reactive O and OH radical in the plasma jet. These results indicate that the generated air plasma jet can be used a plasma sterilization.

  17. Microwave heating and current drive in tokamaks

    SciTech Connect

    Cohen, B.I.; Cohen, R.H.; Kerbel, G.D.; Logan, B.G.; Matsuda, Y.; McCoy, M.G.; Nevins, W.M.; Rognlien, T.D.; Smith, G.R.; Harvey, R.W.; Kritz, A.H.; Bonoli, P.T.; Porkolab, M.

    1988-08-23

    The use of powerful microwave sources provide unique opportunities for novel and efficient heating and current-drive schemes in the electron-cyclotron and lower-hybrid ranges of frequencies. Free- electron lasers and relativistic klystrons are new sources that have a number of technical advantages over conventional, lower-intensity sources; their use can lead to improved current-drive efficiencies and better penetration into a reactor-grade plasma in specific cases. This paper reports on modeling of absorption and current drive, in intense-pulse and quasilinear regimes, and on analysis of parametric instabilities and self-focusing. 16 refs., 2 figs.

  18. Cold Atmosphere Plasma in Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Keidar, Michael

    2012-10-01

    Plasma is an ionized gas that is typically generated in high-temperature laboratory conditions. Recent progress in atmospheric plasmas led to the creation of cold plasmas with ion temperature close to room temperature. Areas of potential application of cold atmospheric plasmas (CAP) include dentistry, drug delivery, dermatology, cosmetics, wound healing, cellular modifications, and cancer treatment. Various diagnostic tools have been developed for characterization of CAP including intensified charge-coupled device cameras, optical emission spectroscopy and electrical measurements of the discharge propertied. Recently a new method for temporally resolved measurements of absolute values of plasma density in the plasma column of small-size atmospheric plasma jet utilizing Rayleigh microwave scattering was proposed [1,2]. In this talk we overview state of the art of CAP diagnostics and understanding of the mechanism of plasma action of biological objects. The efficacy of cold plasma in a pre-clinical model of various cancer types (long, bladder, and skin) was recently demonstrated [3]. Both in-vitro and in-vivo studies revealed that cold plasmas selectively kill cancer cells. We showed that: (a) cold plasma application selectively eradicates cancer cells in vitro without damaging normal cells. For instance a strong selective effect was observed; the resulting 60--70% of lung cancer cells were detached from the plate in the zone treated with plasma, whereas no detachment was observed in the treated zone for the normal lung cells under the same treatment conditions. (b) Significantly reduced tumor size in vivo. Cold plasma treatment led to tumor ablation with neighbouring tumors unaffected. These experiments were performed on more than 10 mice with the same outcome. We found that tumors of about 5mm in diameter were ablated after 2 min of single time plasma treatment. The two best known cold plasma effects, plasma-induced apoptosis and the decrease of cell migration

  19. Polymeric flocculants processing by accelerated electron beams and microwave heating

    NASA Astrophysics Data System (ADS)

    Martin, Diana I.; Mateescu, Elena; Craciun, Gabriela; Ighigeanu, Daniel; Ighigeanu, Adelina

    2002-08-01

    Results obtained by accelerated electron beam, microwave and simultaneous microwave and electron beam application in the chemistry of acrylamide and acrylic acid copolymers (polymeric flocculants used for wastewater treatment) are presented. Comparative results concerning the molecular weight and Huggins' constant for the acrylamide and acrylic acid copolymers obtained by classical heating, microwave heating, electron beam irradiation and simultaneous microwave and electron beam treatment are reported. Microwave heating produces high water solubility of the polymeric flocculants but median molecular weight values. Electron beam irradiation gives high molecular weight values but associated with a cross-linked structure (poor water solubility) while microwave energy addition to electron beam energy gives simultaneously high molecular weight values and high water solubility.

  20. Microwave heating for the rapid generation of glycosylhydrazides.

    PubMed

    Mallevre, F; Roget, A; Minon, T; Kervella, Y; Ropartz, D; Ralet, M C; Canut, H; Livache, T

    2013-07-17

    Conditions for simple derivatization of reducing carbohydrates via adipic acid dihydrazide microwave-assisted condensation are described. We demonstrate with a diverse set of oligo- and polysaccharides how to improve a restrictive and labor intensive conventional conjugation protocol by using microwave-assisted chemistry. We show that 5 min of microwave heating in basic or acidic conditions are adequate to generate, in increased yields, intact and functional glycosylhydrazides, whereas hours to days and acidic conditions are generally required under conventional methods. PMID:23731134

  1. Structural characteristics of pumpkin pectin extracted by microwave heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To improve extraction yield of pumpkin pectin, microwave heating was adopted in this study. Using traditional hot acid extraction, pumpkin pectin yield decreased from 5.7 to 1.0 % as pH increased from pH 1.0 to 2.0. At pH 2.5, no pectin was recovered from pumpkin flesh powder. After a pre-treatment ...

  2. Microwave heating effect on rheology and microstructure of white sauces.

    PubMed

    Guardeño, Luis M; Sanz, Teresa; Fiszman, Susana M; Quiles, Amparo; Hernando, Isabel

    2011-10-01

    The microstructure and rheological properties of white sauces formulated with different starches were analyzed after being microwave-heated for different times. Significant differences (P < 0.05) in rheological parameters analyzed-storage modulus (G'), loss modulus (G″), and loss tangent (tanδ)-were obtained for sauces made with different starches. Microwave reheating did not affect G' and G″ values until water evaporation became significant. In addition, tanδ values did not change significantly (P < 0.05) even during long reheating times showing that sauce viscoelastic properties did not change after microwave irradiation. However, microstructure assessed by confocal laser scanning microscopy showed changes in fat globule and protein. These microstructural changes did not seem to have a significant effect on rheological measurements since starch and ι-carrageenan are mainly responsible for the viscoelastic behavior of the sauces. Practical Application:  The development of products appropriate to microwave heating is constantly rising in food industry. It is necessary to understand the behavior of the ingredients and the final product to microwave heating in order to choose those ingredients which will develop the best performance. Starches are common ingredients in industrial sauces, and rheological and microstructural techniques have shown their usefulness in characterization of starch-based systems. PMID:21913921

  3. 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.

  4. Stability of the Io plasma torus/atmosphere interaction

    NASA Technical Reports Server (NTRS)

    Johnson, R. E.; Mcgrath, Melissa

    1993-01-01

    The stability of the Io plasma torus-atmosphere interaction is examined. A simple plasma deflection model describes how transients in the plasma flux and the content of the atmosphere affect the ionospheric conductance, limiting the plasma bombardment and, hence, the supply of atmospheric species to the torus. The supply of the torus is seen to be determined by the thermal structure of the plasma, namely, the amount of low energy plasma producing atmospheric erosion vs. that which produces ionization, so that the torus supply rate is not simply proportional to the torus ion density.

  5. [Study on catalytic oxidation of benzene by microwave heating].

    PubMed

    Zhang, Yu-cai; Bo, Long-li; Wang, Xiao-hui; Liu, Hai-nan; Zhang, Hao

    2012-08-01

    The performance in catalytic oxidation of benzene was investigated in two different heating modes, microwave heating and conventional electric furnace heating. The effects of copper (Cu)-manganese (Mn) mass ratio, doping dose of cerium (Ce) and calcination temperature on the catalytic activity of Cu-Mn-Ce/molecular sieve catalyst were also checked in catalytic oxidation of benzene with microwave heating, and the catalysts were subsequently characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results showed that the catalyst had better catalytic activity for the oxidation of benzene under microwave heating than electric furnace heating, and high oxidation efficiency for benzene was reached due to the "local hot spots" and dipole polarization effect of microwave and stable bed reaction temperature. Under the conditions of Cu, Mn and Ce mass ratio 1:1:0.33 and calcination temperature 500 degrees C, the catalyst had the optimal catalytic activity for benzene oxidation, and its light-off temperature and complete combustion temperature were 165 degrees C and 230 degrees C, respectively. It was indicated by characteristics of XRD and SEM that the presence of copper and manganese oxides and Cu1.5Mn1.5O4 with spinel crystal improved the catalytic activity of the catalyst, and the doping of Ce promoted the dispersion and regularization of active components. High calcination temperature led to the sintering of the catalyst surface and agglomeration of active components, which decreased the catalytic activity of the catalyst in the catalytic oxidation PMID:23213902

  6. Thermal runaway in microwave heated isothermal slabs, cylinders, and spheres

    NASA Astrophysics Data System (ADS)

    Vriezinga, C. A.

    1998-01-01

    The absorption of electromagnetic energy within a microwave heated isothermal slab, cylinder, and sphere is analyzed and compared to each other. It is shown that the absorbed heat oscillates as a function of temperature, regardless of the geometry of the irradiated object. It is possible to formulate this behavior in a simple mathematical equation, which proves that the oscillation is basically caused by resonance of the electromagnetic waves within the object. This oscillation, combined with the heat loss, is found to be responsible for thermal runaway phenomenon in isothermal objects. Based on such an observation, a general rule to prevent thermal runaway has been developed.

  7. Dynamic measurement of starch granule swelling during microwave heating.

    PubMed

    Casasnovas, Johnny; Anantheswaran, Ramaswamy C

    2016-10-20

    The size of starch granules in dilute aqueous suspension was measured in-line during gelatinization in a microwave-heated, well-mixed system. The results were compared with those of a previous study conducted with conventional heating. For the starches used (common corn, waxy maize, and cross-linked waxy maize), no significant difference was found between microwave and conventional heating in terms of maximum diameter, temperature of maximum rate of diameter increase, or diameter vs. temperature behavior. These results suggest that there are no differences in the swelling behavior of common and modified maize starches between microwave and conventional heating. PMID:27474654

  8. Pluto's atmosphere-plasma interaction: Hybrid simulations

    NASA Astrophysics Data System (ADS)

    Delamere, P. A.; Bagenal, F.; Strobel, D. F.; Barnes, N. P.; McComas, D. J.; Elliott, H. A.; Hill, M. E.; McNutt, R. L., Jr.

    2015-12-01

    Pluto's low gravity implies that the atmosphere is only weakly bound. The escaping neutrals are photoionized and the heavy ions (N2+) move away from Pluto in the direction perpendicular to the solar wind flow (i.e., nearly unmagnetized relative to the length scales of the plasma interaction region). The turning distance of the solar wind protons at the magnetic pileup boundary is large compared to the interaction region. As a result, large ion gyroradius effects determine Pluto's highly asymmetric interaction with the solar wind. We use a three-dimensional hybrid code (fluid electrons, kinetic ions) to investigate the geometry of the interaction region using recent atmospheric models for hybrid simulation input. We will present initial results, showing the sensitivity of bow shock location to variations in the model atmosphere as well as variations in the solar wind conditions. Synthetic energy spectrograms taken from the simluations could be directly compared with the New Horizons plasma data to further constrain model input parameters. Initial results indicate that a full bow shock could form with possible structuring in the wake region due to bi-ion waves and Kelvin-Helmholtz waves.

  9. Higher Fe{sup 2+}/total Fe ratio in iron doped phosphate glass melted by microwave heating

    SciTech Connect

    Mandal, Ashis K.; Sinha, Prasanta K.; Das, Dipankar; Guha, Chandan; Sen, Ranjan

    2015-03-15

    Highlights: • Iron doped phosphate glasses prepared using microwave heating and conventional heating under air and reducing atmosphere. • Presence of iron predominantly in the ferrous oxidation state in all the glasses. • Significant concentrations of iron in the ferrous oxidation state on both octahedral and tetrahedral sites in all the glasses. • Ratio of Fe{sup 2+} with total iron is found higher in microwave prepared glasses in comparison to conventional prepared glasses. - Abstract: Iron doped phosphate glasses containing P{sub 2}O{sub 5}–MgO–ZnO–B{sub 2}O{sub 3}–Al{sub 2}O{sub 3} were melted using conventional resistance heating and microwave heating in air and under reducing atmosphere. All the glasses were characterised by UV–Vis–NIR spectroscopy, Mössbauer spectroscopy, thermogravimetric analysis and wet colorimetry analysis. Mössbauer spectroscopy revealed presence of iron predominantly in the ferrous oxidation state on two different sites in all the glasses. The intensity of the ferrous absorption peaks in UV–Vis–NIR spectrum was found to be more in glasses prepared using microwave radiation compared to the glasses prepared in a resistance heating furnace. Thermogravimetric analysis showed increasing weight gain on heating under oxygen atmosphere for glass corroborating higher ratio of FeO/(FeO + Fe{sub 2}O{sub 3}) in glass melted by direct microwave heating. Wet chemical analysis also substantiated the finding of higher ratio Fe{sup +2}/ΣFe in microwave melted glasses. It was found that iron redox ratio was highest in the glasses prepared in a microwave furnace under reducing atmosphere.

  10. Mass spectrometry of atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Große-Kreul, S.; Hübner, S.; Schneider, S.; Ellerweg, D.; von Keudell, A.; Matejčík, S.; Benedikt, J.

    2015-08-01

    Atmospheric pressure non-equilibrium plasmas (APPs) are effective source of radicals, metastables and a variety of ions and photons, ranging into the vacuum UV spectral region. A detailed study of these species is important to understand and tune desired effects during the interaction of APPs with solid or liquid materials in industrial or medical applications. In this contribution, the opportunities and challenges of mass spectrometry for detection of neutrals and ions from APPs, fundamental physical phenomena related to the sampling process and their impact on the measured densities of neutrals and fluxes of ions, will be discussed. It is shown that the measurement of stable neutrals and radicals requires a proper experimental design to reduce the beam-to-background ratio, to have little beam distortion during expansion into vacuum and to carefully set the electron energy in the ionizer to avoid radical formation through dissociative ionization. The measured ion composition depends sensitively on the degree of impurities present in the feed gas as well as on the setting of the ion optics used for extraction of ions from the expanding neutral-ion mixture. The determination of the ion energy is presented as a method to show that the analyzed ions are originating from the atmospheric pressure plasma.

  11. An experimental study of waveguide coupled microwave heating with conventional multicusp negative ion sources

    SciTech Connect

    Komppula, J.; Kalvas, T.; Koivisto, H.; Laulainen, J.; Tarvainen, O.

    2015-04-08

    Negative ion production with conventional multicusp plasma chambers utilizing 2.45 GHz microwave heating is demonstrated. The experimental results were obtained with the multicusp plasma chambers and extraction systems of the RF-driven RADIS ion source and the filament driven arc discharge ion source LIISA. A waveguide microwave coupling system, which is almost similar to the one used with the SILHI ion source, was used. The results demonstrate that at least one third of negative ion beam obtained with inductive RF-coupling (RADIS) or arc discharge (LIISA) can be achieved with 1 kW of 2.45 GHz microwave power in CW mode without any modification of the plasma chamber. The co-extracted electron to H{sup −} ratio and the optimum pressure range were observed to be similar for both heating methods. The behaviour of the plasma implies that the energy transfer from the microwaves to the plasma electrons is mainly an off-resonance process.

  12. Analysis of Sterilization Effect of Atmospheric Pressure Pulsed Plasma

    SciTech Connect

    Ekem, N.; Akan, T.; Pat, S.; Akgun, Y.; Kiremitci, A.; Musa, G.

    2007-04-23

    We have developed a new technology, the High Voltage Atmospheric Pressure Pulsed Plasma (HVAPPP), for bacteria killing. The aim of this paper is to present a simple device to generate plasma able to kill efficiently bacteria.

  13. Low-temperature atmospheric-pressure plasma sources for plasma medicine.

    PubMed

    Setsuhara, Yuichi

    2016-09-01

    In this review paper, fundamental overviews of low-temperature atmospheric-pressure plasma generation are provided and various sources for plasma medicine are described in terms of operating conditions and plasma properties. PMID:27109191

  14. Synthesis and Modification of Carbon Nanomaterials utilizing Microwave Heating.

    PubMed

    Schwenke, Almut M; Hoeppener, Stephanie; Schubert, Ulrich S

    2015-07-22

    Microwave-assisted synthesis and processing represents a growing field in materials research and successfully entered the field of carbon nanomaterials during the last decade. Due to the strong interaction of carbon materials with microwave radiation, fast heating rates and localized heating can be achieved. These features enable the acceleration of reaction processes, as well as the formation of nanostructures with special morphologies. A comprehensive overview is provided here on the possibilities and achievements in the field of carbon-nanomaterial research when using microwave-based heating approaches. This includes the synthesis and processing of carbon nanotubes and fibers, graphene materials, carbon nanoparticles, and capsules, as well as porous carbon materials. Additionally, the principles of microwave-heating, in particular of carbon materials, are introduced and important issues, i.e., safety and reproducibility, are discussed. PMID:26087742

  15. Martian Atmospheric and Ionospheric plasma Escape

    NASA Astrophysics Data System (ADS)

    Lundin, Rickard

    2016-04-01

    Solar forcing is responsible for the heating, ionization, photochemistry, and erosion processes in the upper atmosphere throughout the lifetime of the terrestrial planets. Of the four terrestrial planets, the Earth is the only one with a fully developed biosphere, while our kin Venus and Mars have evolved into arid inhabitable planets. As for Mars, there are ample evidences for an early Noachian, water rich period on Mars. The question is, what made Mars evolve so differently compared to the Earth? Various hydrosphere and atmospheric evolution scenarios for Mars have been forwarded based on surface morphology, chemical composition, simulations, semi-empiric (in-situ data) models, and the long-term evolution of the Sun. Progress has been made, but the case is still open regarding the changes that led to the present arid surface and tenuous atmosphere at Mars. This presentation addresses the long-term variability of the Sun, the solar forcing impact on the Martian atmosphere, and its interaction with the space environment - an electromagnetic wave and particle interaction with the upper atmosphere that has implications for its photochemistry, composition, and energization that governs thermal and non-thermal escape. Non-thermal escape implies an electromagnetic upward energization of planetary ions and molecules to velocities above escape velocity, a process governed by a combination of solar EUV radiation (ionization), and energy and momentum transfer by the solar wind. The ion escape issue dates back to the early Soviet and US-missions to Mars, but the first more accurate estimates of escape rates came with the Phobos-2 mission in 1989. Better-quality ion composition measurement results of atmospheric/ionospheric ion escape from Mars, obtained from ESA Mars Express (MEX) instruments, have improved our understanding of the ion escape mechanism. With the NASA MAVEN spacecraft orbiting Mars since Sept. 2014, dual in-situ measurement with plasma instruments are now

  16. Nonthermal Atmospheric Plasmas in Dental Restoration.

    PubMed

    Liu, Y; Liu, Q; Yu, Q S; Wang, Y

    2016-05-01

    It is well known that the service life of contemporary composite restoration is unsatisfactory, and longevity of dentin bonding is one of the major culprits. Bonding is essentially a hybridization process in which dental substrate and adhesive resin interact with each other through an exchange process. Thus, the longevity of dentin bonding can only be improved with enhanced qualities in substrate, adhesive resin, and their interaction within the hybridization zone. This review aims to collect and summarize recent advances in utilizing nonthermal atmospheric plasmas (NTAPs)-a novel technology that delivers highly reactive species in a gaseous medium at or below physiologic temperature-to improve the durability of dentin bonding by addressing these 3 issues simultaneously. Overall, NTAP has demonstrated efficacies in improving a number of critical properties for dentin bonding, including deactivation of oral pathogens, modification of surface chemistry/properties, resin polymerization, improvement in adhesive-dentin interactions, and establishment of auxiliary bonding mechanism. While a few preliminary studies have indicated the benefit of NTAP to bond strength and stability, additional researches are warranted to employ knowledge acquired so far and to evaluate these properties in a systematic way. PMID:26848068

  17. Charge dependence of the plasma travel length in atmospheric-pressure plasma

    NASA Astrophysics Data System (ADS)

    Yambe, Kiyoyuki; Konda, Kohmei; Masuda, Seiya

    2016-06-01

    Plasma plume is generated using a quartz tube, helium gas, and foil electrode by applying AC high voltage under the atmosphere. The plasma plume is released into the atmosphere from inside of the quartz tube and is seen as the continuous movement of the plasma bullet. The travel length of plasma bullet is defined from plasma energy and force due to electric field. The drift velocity of plasma bullet has the upper limit under atmospheric-pressure because the drift velocity is determined from the balance between electric field and resistive force due to collisions between plasma and air. The plasma plume charge depends on the drift velocity. Consequently, in the laminar flow of helium gas flow state, the travel length of the plasma plume logarithmically depends on the plasma plume charge which changes with both the electric field and the resistive force.

  18. Atmospheric pressure plasma jet for liquid spray treatment

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  19. Spatial observation and quantification of microwave heating in materials

    NASA Astrophysics Data System (ADS)

    Crane, C. A.; Pantoya, M. L.; Weeks, B. L.

    2013-08-01

    An electromagnetic exposure chamber was designed to safely deliver electromagnetic power in the range of microwaves between 0.8 and 4.2 GHz to a thin cylindrical materials. This instrumentation is unique because the diagnostics not only measure sample heating with a response time of 1.3 ms, but also energy transmitted and reflected. Energy absorption at different frequencies was quantified via electromagnetic heating using an infrared camera. This in situ IR imaging of the spatial distribution of temperature during microwave exposure coupled with sensors for determining transmitted and reflected energy enables novel new microwave energy experiments. Samples were exposed to a portion of both the electric and magnetic fields inside a waveguide and based on sample dimensions, the field strengths were assumed uniform across the sample. Three materials were examined: two were borosilicate, first coated with graphite paint and a second without the coating; and, the third was a compressed sample of flake graphite pressed to 69% of its bulk density. Results are in agreement with the theories of microwave heating and verify the functionality of this experimental design. This diagnostic will be important in future tests where a variety of different materials can be exposed to weak electromagnetic waves and their efficiency in coupling to the microwaves can be examined.

  20. Microwave heating and joining of ceramic cylinders: A mathematical model

    NASA Technical Reports Server (NTRS)

    Booty, Michael R.; Kriegsmann, Gregory A.

    1994-01-01

    A thin cylindrical ceramic sample is placed in a single mode microwave applicator in such a way that the electric field strength is allowed to vary along its axis. The sample can either be a single rod or two rods butted together. We present a simple mathematical model which describes the microwave heating process. It is built on the assumption that the Biot number of the material is small, and that the electric field is known and uniform throughout the cylinder's cross-section. The model takes the form of a nonlinear parabolic equation of reaction-diffusion type, with a spatially varying reaction term that corresponds to the spatial variation of the electromagnetic field strength in the waveguide. The equation is analyzed and a solution is found which develops a hot spot near the center of the cylindrical sample and which then propagates outwards until it stabilizes. The propagation and stabilization phenomenon concentrates the microwave energy in a localized region about the center where elevated temperatures may be desirable.

  1. Effects of polarization-charge shielding in microwave heating

    SciTech Connect

    Lin, M. S.; Lin, S. M.; Chiang, W. Y.; Barnett, L. R.; Chu, K. R.

    2015-08-15

    Heating of dielectric objects by radio frequency (RF) and microwaves has long been a method widely employed in scientific research and industrial applications. However, RF and microwave heating are often susceptible to an excessive temperature spread due to uneven energy deposition. The current study elucidates an important physical reason for this difficulty and proposes an effective remedy. Non-spherical samples are placed in an anechoic chamber, where it is irradiated by a traveling microwave wave with 99% intensity uniformity. Polarization charges induced on the samples tend to partially cancel the incident electric field and hence reduce the heating rate. The polarization-charge shielded heating rate is shown to be highly dependent on the sample's shape and its orientation relative to the wave electric field. For samples with a relatively high permittivity, the resultant uneven heating can become a major cause for the excessive temperature spread. It is also demonstrated that a circularly polarized wave, with its rapidly rotating electric field, can effectively even out the heating rate and hence the temperature spread.

  2. Development of a combinatorial atmospheric pressure cold plasma processor

    NASA Astrophysics Data System (ADS)

    Terajima, Takeshi; Koinuma, Hideomi

    2004-02-01

    Low-temperature plasma can be generated under atmospheric pressure by applying an RF (13.56 MHz) voltage between parallel electrodes, the surfaces of which are preferably covered with an insulator. Applications of this atmospheric pressure cold plasma include thin film deposition, chemical synthesis, etching, resist-ashing, surface treatment, and sterilization. For seeking further improvement of the system and more applications, we have developed a combinatorial atmospheric pressure cold plasma generator to fabricate composition spread thin films by synchronizing the variation of feeding gas ratio with the substrate stage motion. This system can be extended to fabricating a variety of combinatorial libraries by controlling other parameters in the operation such as the gas flow rate, the RF power, substrate temperature, and the treatment time. The utility of this combinatorial plasma process has been demonstrated with the plasma copolymerization of CO 2 with ethylene to fix CO 2 into the plasma polymerized film in the form of ester linkage.

  3. Optimization and stabilization of gold nanoparticles by using herbal plant extract with microwave heating

    NASA Astrophysics Data System (ADS)

    Yasmin, Akbar; Ramesh, Kumaraswamy; Rajeshkumar, Shanmugam

    2014-04-01

    In this study, we have synthesized the gold nanoparticles by using Hibiscus rosa-sinensis, a medicinal plant. The gold nanoparticles were synthesized rapidly by the involvement of microwave heating. By changing of plant extract concentration, gold solution concentration, microwave heating time and power of microwave heating the optimized condition was identified. The surface Plasmon resonance found at 520 nm confirmed the gold nanoparticles synthesis. The spherical sized nanoparticles in the size range of 16-30 nm were confirmed by Transmission Electron Microscope (TEM). The stability of the nanoparticles is very well proved in the invitro stability tests. The biochemical like alkaloids and flavonoids play a vital role in the nanoparticles synthesis was identified using the Fourier Transform Infrared Spectroscopy (FTIR). Combining the phytochemical and microwave heating, the rapid synthesis of gold nanoparticles is the novel process for the medically applicable gold nanoparticles production.

  4. Diagnostics of transient non-equilibrium atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Bruggeman, Peter

    2015-09-01

    Atmospheric pressure plasmas have received a renewed interest in last decades for a variety of applications ranging from environmental remediation, material processing and synthesis to envisioned medical applications such as wound healing. While most low pressure plasmas are diffuse, atmospheric pressure plasmas are often filamentary in nature. The existence of these filaments is correlated with strong gradients in plasma properties both in space and time that can significantly affect the plasma chemistry. As these filaments are often randomly appearing in space and time, it poses great challenges for diagnostics often requiring the stabilization of the filament to study the in situ plasma kinetics. In this contribution, diagnostics of a stabilized nanosecond pulsed plasma filament in a pin-pin geometry and a filament in a nanosecond pulsed atmospheric pressure plasma jet will be presented. We will focus on electron kinetics and OH and H radical production in water containing plasmas. The extension of these diagnostics to plasmas in liquids will also be discussed. The author acknowledges support from NSF PHYS1500135, Department of Energy Plasma Science Center through the U.S. Department of Energy, Office of Fusion Energy Sciences (Contract No. DE-SC0001939), University of Minnesota and STW (Netherlands).

  5. Atmospheric pressure non-thermal plasma: Sources and applications

    NASA Astrophysics Data System (ADS)

    Napartovich, A. P.

    2008-07-01

    Non-thermal plasma at atmospheric pressure is an inherently unstable object. Nature of discharge plasma instabilities and conditions for observation of uniform non-thermal plasma at atmospheric pressure in different environments will be discussed. Various discharge techniques have been developed, which could support uniform non-thermal plasma with parameters varied in a wide range. Time limitation by plasma instabilities can be overcome by shortening pulse length or by restriction of plasma plug residence time with a fast gas flow. Discharge instabilities leading to formation of filaments or sparks are provoked by a positive feedback between the electric field and plasma density, while the counteracting process is plasma and thermal diffusion. With gas pressure growth the size of plasma fluctuation, which could be stabilized by diffusion, diminishes. As a result, to have long lived uniform plasma one should miniaturize discharge. There exist a number of active methods to organize negative feedback between the electric field and plasma density in order to suppress or, at least, delay the instability. Among them are ballast resistors in combination with electrode sectioning, reactive ballast, electronic feedback, and dielectric barrier across the electric current. The last methods are relevant for ac discharges. In the lecture an overview will be given of different discharge techniques scalable in pressure up to one atmosphere. The interest in this topic is dictated by a potential economic benefit from numerous non-thermal plasma technologies. The spectrum of non-thermal plasma applications is continuously broadening. An incomplete list of known applications includes: plasma-assisted chemical vapor deposition, etching, polymerization, gas-phase synthesis, protective coating deposition, toxic and harmful gas decomposition, destruction of warfare agents, electromagnetic wave shielding, polymer surface modifications, gas laser excitation, odor control, plasma assisted

  6. 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.

  7. 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.

  8. Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma

    NASA Technical Reports Server (NTRS)

    Cooper, Moogega; Vaze, Nachiket; Anderson, Shawn; Fridman, Gregory; Vasilets, Victor N.; Gutsol, Alexander; Tsapin, Alexander; Fridman, Alexander

    2007-01-01

    As a solution to chemically and thermally destructive sterilization methods currently used for spacecraft, non-equilibrium atmospheric pressure plasmas are used to treat surfaces inoculated with Bacillus subtilis and Deinococcus radiodurans. Evidence of significant morphological changes and reduction in viability due to plasma exposure will be presented, including a 4-log reduction of B. subtilis after 2 minutes of dielectric barrier discharge treatment.

  9. Plasma-ion Induced Sputtering and Heating of Titan's Atmosphere

    NASA Astrophysics Data System (ADS)

    Johnson, R. E.; Tucker, O. J.

    2007-05-01

    Titan is unique among the outer solar system icy satellites in having an atmosphere with a column density about ten times that of the Earth's atmosphere and an atmospheric mass to solid mass ratio comparable to that of Venus. Atmospheres equivalent in size to that at Titan would have been removed from the icy Galilean satellites by the plasma trapped in the Jovian magnetosphere (Johnson 2004). Therefore, the use of Cassini data to determine the present erosion rate of Titan's atmosphere provides an important end point for studying the erosion and heating of planetary and satellite atmospheres by an ambient plasma. In this paper we describe the deposition of energy, the erosion and the expansion of the upper atmosphere of Titan using Direct Simulation Monte Carlo models (Shematovich et al. 2003; Michael et al. 2005; Michael and Johnson 2005). These calculations are used to calibrate semi-empirical models of atmospheric sputtering (Johnson 1994) that are used to interpret Cassini data at Titan. Using a number of plasma conditions, the temperature and density vs. altitude above the exobase and the rate of escape are calculated. References: Johnson, R.E. "Plasma-induced Sputtering of an Atmosphere" in Space Science Reviews 69 215-253 (1994). Johnson. R.E., " The magnetospheric plasmadriven evolution of satellite atmospheres" Astrophys. J. 609, L99-L102 (2004). Michael, M. and R.E. Johnson, "Energy deposition of pickup ions and heating of Titan's atmosphere", Planetary & Space Sci.53, 1510-1514 (2005). Michael M., R.E. Johnson, F. Leblanc, M. Liu, J.G. Luhmann, and V.I. Shematovich, "Ejection of nitrogen from Titan's atmosphere by magnetospheric ions and pick-up ions", Icarus 175, 263-267 (2005). Shematovich, V.I., R.E. Johnson, M. Michael, and J.G. Luhmann, "Nitrogen loss from Titan", JGR 108, No. E8, 5087, doi:10.1029/2003JE002094 (2003).

  10. 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.

  11. Status and potential of atmospheric plasma processing of materials

    SciTech Connect

    Pappas, Daphne

    2011-03-15

    This paper is a review of the current status and potential of atmospheric plasma technology for materials processing. The main focus is the recent developments in the area of dielectric barrier discharges with emphasis in the functionalization of polymers, deposition of organic and inorganic coatings, and plasma processing of biomaterials. A brief overview of both the equipment being used and the physicochemical reactions occurring in the gas phase is also presented. Atmospheric plasma technology offers major industrial, economic, and environmental advantages over other conventional processing methods. At the same time there is also tremendous potential for future research and applications involving both the industrial and academic world.

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

    NASA Astrophysics Data System (ADS)

    Shashurin, A.; Keidar, M.

    2015-12-01

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

  13. Seed disinfection effect of atmospheric pressure plasma and low pressure plasma on Rhizoctonia solani.

    PubMed

    Nishioka, Terumi; Takai, Yuichiro; Kawaradani, Mitsuo; Okada, Kiyotsugu; Tanimoto, Hideo; Misawa, Tatsuya; Kusakari, Shinichi

    2014-01-01

    Gas plasma generated and applied under two different systems, atmospheric pressure plasma and low pressure plasma, was used to investigate the inactivation efficacy on the seedborne pathogenic fungus, Rhizoctonia solani, which had been artificially introduced to brassicaceous seeds. Treatment with atmospheric plasma for 10 min markedly reduced the R. solani survival rate from 100% to 3% but delayed seed germination. The low pressure plasma treatment reduced the fungal survival rate from 83% to 1.7% after 10 min and the inactivation effect was dependent on the treatment time. The seed germination rate after treatment with the low pressure plasma was not significantly different from that of untreated seeds. The air temperature around the seeds in the low pressure system was lower than that of the atmospheric system. These results suggested that gas plasma treatment under low pressure could be effective in disinfecting the seeds without damaging them. PMID:24975415

  14. Three electrode atmospheric pressure plasma jet in helium flow

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  15. Influence of Atmospheric Pressure Torch Plasma Irradiation on Plant Growth

    NASA Astrophysics Data System (ADS)

    Akiyoshi, Yusuke; Hayashi, Nobuya; Kitazaki, Satoshi; Koga, Kazunori; Shiratani, Masaharu

    2011-10-01

    Growth stimulation characteristics of plants seeds are investigated by an atmospheric discharge irradiation into plasma seeds. Atmospheric pressure plasma torch is consisted of alumina ceramics tube and the steel mesh electrodes wind inside and outside of the tube. When AC high voltage (8 kHz) is applied to the electrode gap, the barrier discharge plasma is produced inside the alumina ceramics tube. The barrier discharge plasma is blown outside with the gas flow in ceramics tube. Radish sprouts seeds locate at 1 cm from the torch edge. The growth stimulation was observed in the length of a stem and a root after the plasma irradiation. The stem length increases approximately 2.8 times at the cultivation time of 24 h. And the growth stimulation effect is found to be maintained for 40 h, after sowing seeds. The mechanism of the growth stimulation would be the redox reaction inside plant cells induced by oxygen radicals.

  16. Plasma-ion-induced sputtering and heating of Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Johnson, R. E.; Michael, M.; Tucker, O. J.; Shematovich, V. I.; Luhmann, J. H.; Ledvina, S. A.

    Titan is unique among the outer solar system icy satellites in having an atmosphere with a column density about ten times that of the Earth's atmosphere and an atmosphere mass to solid mass ratio comparable to that of Venus. Atmospheres equivalent in size to that at Titan would have been removed from the icy Galilean satellites by the plasma trapped in the Jovian magnetosphere (Johnson 2004). Therefore, the fact that data from the Cassini spacecraft can be used to determine the present erosion rate of Titan's atmosphere by the plasma trapped in Saturn's magnetosphere provides an exciting end point for studying the erosion and heating of planetary and satellite atmospheres by an ambient plasma. In this paper we describe the deposition of energy, the erosion and the expansion of the upper atmosphere of Titan using Direct Simulation Monte Carlo models (Shematovich et al. 2003; Michael et al. 2005; Michael and Johnson 2005). These calculations are used to calibrate semi-empirical models of atmospheric sputtering (Johnson 1994) that can, in principal, be employed in interpreting Cassini data at Titan. It is shown that the globally averaged flux of magnetospheric and pickup ions deposit more energy in Titan's upper atmosphere than solar radiation. Using a number of plasma conditions, the temperature and density vs. altitude above the exobase and the rate of escape are calculated and compared to available Cassini data. References: Johnson, R.E. "Plasma-induced Sputtering of an Atmosphere" in Space Science Reviews 69 215-253 (1994). Johnson. R.E., " The magnetospheric plasma- driven evolution of satellite atmospheres" Astrophys. J. 609, L99-L102 (2004). Michael, M. and R.E. Johnson, "Energy deposition of pickup ions and heating of Titan's atmosphere", Planetary & Space Sci.53, 1510-1514 (2005). Michael M., R.E. Johnson, F. Leblanc, M. Liu, J.G. Luhmann, and V.I. Shematovich, "Ejection of nitrogen from Titan's atmosphere by magnetospheric ions and pick-up ions", Icarus 175

  17. Atmospheric pressure cold plasma as an antifungal therapy

    SciTech Connect

    Sun Peng; Wu Haiyan; Sun Yi; Liu Wei; Li Ruoyu; Zhu Weidong; Lopez, Jose L.; Zhang Jue; Fang Jing

    2011-01-10

    A microhollow cathode based, direct-current, atmospheric pressure, He/O{sub 2} (2%) cold plasma microjet was used to inactive antifungal resistants Candida albicans, Candida krusei, and Candida glabrata in air and in water. Effective inactivation (>90%) was achieved in 10 min in air and 1 min in water. Antifungal susceptibility tests showed drastic reduction of the minimum inhibitory concentration after plasma treatment. The inactivation was attributed to the reactive oxygen species generated in plasma or in water. Hydroxyl and singlet molecular oxygen radicals were detected in plasma-water system by electron spin resonance spectroscopy. This approach proposed a promising clinical dermatology therapy.

  18. Parameters of atmospheric plasmas produced by electrosurgical devices

    NASA Astrophysics Data System (ADS)

    Keidar, Michael; Shashurin, Alexey; Canady, Jerome

    2013-10-01

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

  19. Atmospheric pressure cold plasma as an antifungal therapy

    NASA Astrophysics Data System (ADS)

    Sun, Peng; Sun, Yi; Wu, Haiyan; Zhu, Weidong; Lopez, Jose L.; Liu, Wei; Zhang, Jue; Li, Ruoyu; Fang, Jing

    2011-01-01

    A microhollow cathode based, direct-current, atmospheric pressure, He/O2 (2%) cold plasma microjet was used to inactive antifungal resistants Candida albicans, Candida krusei, and Candida glabrata in air and in water. Effective inactivation (>90%) was achieved in 10 min in air and 1 min in water. Antifungal susceptibility tests showed drastic reduction of the minimum inhibitory concentration after plasma treatment. The inactivation was attributed to the reactive oxygen species generated in plasma or in water. Hydroxyl and singlet molecular oxygen radicals were detected in plasma-water system by electron spin resonance spectroscopy. This approach proposed a promising clinical dermatology therapy.

  20. 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.

  1. Etching of photoresist with an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  2. Relation between plasma plume density and gas flow velocity in atmospheric pressure plasma

    SciTech Connect

    Yambe, Kiyoyuki; Taka, Shogo; Ogura, Kazuo

    2014-04-15

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and copper foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. To study the properties of the plasma plume, the plasma plume current is estimated from the difference in currents on the circuit, and the drift velocity is measured using a photodetector. The relation of the plasma plume density n{sub plu}, which is estimated from the current and the drift velocity, and the gas flow velocity v{sub gas} is examined. It is found that the dependence of the density on the gas flow velocity has relations of n{sub plu} ∝ log(v{sub gas}). However, the plasma plume density in the laminar flow is higher than that in the turbulent flow. Consequently, in the laminar flow, the density increases with increasing the gas flow velocity.

  3. MicroScale - Atmospheric Pressure Plasmas

    SciTech Connect

    Sankaran, Mohan

    2012-01-25

    Low-temperature plasmas play an essential role in the manufacturing of integrated circuits which are ubiquitous in modern society. In recent years, these top-down approaches to materials processing have reached a physical limit. As a result, alternative approaches to materials processing are being developed that will allow the fabrication of nanoscale materials from the bottom up. The aim of our research is to develop a new class of plasmas, termed “microplasmas” for nanomaterials synthesis. Microplasmas are a special class of plasmas formed in geometries where at least one dimension is less than 1 mm. Plasma confinement leads to several unique properties including high-pressure stability and non-equilibrium that make microplasams suitable for nanomaterials synthesis. Vapor-phase precursors can be dissociated to homogeneously nucleate nanometer-sized metal and alloyed nanoparticles. Alternatively, metal salts dispersed in liquids or polymer films can be electrochemically reduced to form metal nanoparticles. In this talk, I will discuss these topics in detail, highlighting the advantages of microplasma-based systems for the synthesis of well-defined nanomaterials.

  4. Waterspout - an Atmospheric Aerosol Dusty Plasma

    SciTech Connect

    Rantsev-Kartinov, V.A.

    2005-10-31

    An aerosol -- capillary electrostatic model of a waterspout is submitted. The waterspout is treated as a long-living filament of aerosol plasma, which is formed at electric breakdown of interval between a charged cloud and a vertically floating cylinder, which is individual block of ocean's skeletal structures of revealed recently by author.

  5. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    NASA Astrophysics Data System (ADS)

    Vasile Nastuta, Andrei; Topala, Ionut; Grigoras, Constantin; Pohoata, Valentin; Popa, Gheorghe

    2011-03-01

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  6. Efficacy of Nonthermal Atmospheric Pressure Plasma for Tooth Bleaching

    PubMed Central

    Nam, Seoul Hee; Lee, Hae June; Hong, Jin Woo; Kim, Gyoo Cheon

    2015-01-01

    The conventional light source used for tooth bleaching has the potential to cause thermal damage, and the actual role of the light source is doubtful. In this study, we evaluated bleaching efficacy, temperature, and morphological safety after tooth bleaching with nonthermal atmospheric pressure plasma. Tooth bleaching combined with plasma had improved efficacy in providing a higher level of brightness. The temperature of the pulp chamber was maintained around 37°C, indicating that the plasma does not cause any thermal damage. The morphological results of tooth bleaching with plasma did not affect mineral composition under scanning electron microscopy (SEM) observations. On the basis of these results, the application of plasma and low concentration of 15% carbamide peroxide (CP) has a high capability for effective tooth bleaching. It can be documented that plasma is a safe energe source, which has no deleterious effects on the tooth surface. PMID:25685843

  7. Sterilization of Turmeric by Atmospheric Pressure Dielectric Barrier Discharge Plasma

    NASA Astrophysics Data System (ADS)

    Setareh, Salarieh; Davoud, Dorranian

    2013-11-01

    In this study atmospheric pressure dielectric barrier discharge (DBD) plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/O2, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 min is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.

  8. Generation of nano roughness on fibrous materials by atmospheric plasma

    NASA Astrophysics Data System (ADS)

    Kulyk, I.; Scapinello, M.; Stefan, M.

    2012-12-01

    Atmospheric plasma technology finds novel applications in textile industry. It eliminates the usage of water and of hazard liquid chemicals, making production much more eco-friendly and economically convenient. Due to chemical effects of atmospheric plasma, it permits to optimize dyeing and laminating affinity of fabrics, as well as anti-microbial treatments. Other important applications such as increase of mechanical resistance of fiber sleeves and of yarns, anti-pilling properties of fabrics and anti-shrinking property of wool fabrics were studied in this work. These results could be attributed to the generation of nano roughness on fibers surface by atmospheric plasma. Nano roughness generation is extensively studied at different conditions. Alternative explanations for the important practical results on textile materials and discussed.

  9. Free-floating atmospheric pressure ball plasmas

    NASA Astrophysics Data System (ADS)

    Wurden, G. A.; Ticos, C.; Wang, Z.; Wurden, C. J. V.

    2007-11-01

    A long-lived (0.3 second, 10-20 cm diameter) ball plasma floating in the air above a water surface has been formed and studied in the laboratory. A 0.4 - 1 mF capacitor is charged to 4-5 kV, and subsequently discharged (30-60 Amps, 20-50 msec duration) into central copper cathode held fixed just below the surface of a bucket of water (with a weak solution of various salts in distilled water, such as CuSO4 or CuCl2, LiCl or NaCl). An underwater ring anode completes the circuit. A bubble of hot vapor from the water surface rises up in the first few milliseconds, and changes from a mushroom cloud with stalk, to a detached quasi-spherical object, finally evolving into a vortex ring. The plasma consists of ionized water vapor, with positive salts and OH- radicals, as well as molecular species, and it completely excludes nitrogen or oxygen from the rising plasma structure. A fine boundary layer is visible in orange, in contrast to a green ball interior when using Cu/CuSO4, and filamentary structures are visible at late times. Finally, a whisp of smoke ring is observed as a residue. A variety of visible and infrared imaging (both video and still cameras) are used, along with 200-800 nm time & space resolved spectroscopy, to identify features of this laboratory analog to ball lightning. Possible applications include a windowless ball- plasma powered pulsed copper vapor laser operating at 510 nm.

  10. Microwave-assisted atmospheric pressure plasma polymerization of hexamethyldisiloxane

    NASA Astrophysics Data System (ADS)

    Matsubayashi, Toshiki; Hidaka, Hiroki; Muguruma, Hitoshi

    2016-07-01

    Microwave-assisted atmospheric pressure plasma polymerization is presented. A system with a re-entrant microwave cavity realizes simple matching, stable plasma, and free space under the orifice of plasma steam. Hexamethyldisiloxane is employed as a monomer, while argon is used as a carrier gas. The effective area of the hydrophobic coating film used corresponds to a circle of 20 mm diameter and the deposition rate considered is 5 nm/min. Matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy shows that the coating film has a large molecular weight (>200 kDa), suggesting that a high-crosslinking and three-dimensional polymer matrix is formed and microwave-assisted atmospheric pressure plasma polymerization is fulfilled.

  11. Atmospheric-pressure plasma sources for biomedical applications

    NASA Astrophysics Data System (ADS)

    Park, G. Y.; Park, S. J.; Choi, M. Y.; Koo, I. G.; Byun, J. H.; Hong, J. W.; Sim, J. Y.; Collins, G. J.; Lee, J. K.

    2012-08-01

    Atmospheric-pressure plasmas (APPs) have attracted great interest and have been widely applied in biomedical applications, as due to their non-thermal and reactive properties, they interact with living tissues, cells and bacteria. Various types of plasma sources generated at atmospheric pressure have been developed to achieve better performance in specific applications. This article presents an overview of the general characteristics of APPs and a brief summary of their biomedical applications, and reviews a wide range of these sources developed for biomedical applications. The plasma sources are classified according to their power sources and cover a wide frequency spectrum from dc to microwaves. The configurations and characteristics of plasma sources are outlined and their biomedical applications are presented.

  12. Characterization of the cold atmospheric plasma hybrid source

    NASA Astrophysics Data System (ADS)

    Bárdoš, L.; Baránková, H.

    2005-07-01

    Parameters of the hybrid hollow electrode activated discharge (H-HEAD) source for cold atmospheric plasma applications are described. The source with a simple cylindrical electrode terminated by a gas nozzle combines the microwave antenna plasma with the hollow cathode plasma generated inside the nozzle by a pulsed dc power. The source can produce over 15 cm long plasma plumes at less than 200 sccm of argon and 100 sccm of neon flowing in open air at the microwave power of 400 W (2.4 GHz). Parameters of the hybrid plasma are controlled by both the microwave power and the power delivered to the hollow cathode. An anomalous effect of a sharp increase in the length of the plasma plume at low gas flows is discussed. Results of the optical emission spectroscopy in argon and neon are presented. Optical spectra confirmed the presence of Ti and Fe from the hollow cathode in the plasma. The production of metal increases with the power applied to the hollow cathode. Traces of Ti from the hollow cathode have been found at substrates positioned as far as 2 cm from the cathode. This finding confirms the possibility to use the H-HEAD source for atmospheric physical vapor deposition (PVD) and hybrid PVD and plasma-enhanced chemical-vapor deposition of composite films.

  13. Microwave heating for production of a glass bonded ceramic high-level waste form.

    SciTech Connect

    O'Holleran, T. P.

    2002-07-30

    Argonne National Laboratory has developed a ceramic waste form to immobilize the salt waste from electrometallurgical treatment of spent nuclear fuel. The process is being scaled up to produce bodies of 100 Kg or greater. With conventional heating, heat transfer through the starting powder mixture necessitates long process times. Coupling of 2.45 GHz radiation to the starting powders has been demonstrated. The radiation couples most strongly to the salt occluded zeolite powder. The results of these experiments suggest that this ceramic waste form could be produced using microwave heating alone, or by using microwave heating to augment conventional heating.

  14. A finite element method based microwave heat transfer modeling of frozen multi-component foods

    NASA Astrophysics Data System (ADS)

    Pitchai, Krishnamoorthy

    Microwave heating is fast and convenient, but is highly non-uniform. Non-uniform heating in microwave cooking affects not only food quality but also food safety. Most food industries develop microwavable food products based on "cook-and-look" approach. This approach is time-consuming, labor intensive and expensive and may not result in optimal food product design that assures food safety and quality. Design of microwavable food can be realized through a simulation model which describes the physical mechanisms of microwave heating in mathematical expressions. The objective of this study was to develop a microwave heat transfer model to predict spatial and temporal profiles of various heterogeneous foods such as multi-component meal (chicken nuggets and mashed potato), multi-component and multi-layered meal (lasagna), and multi-layered food with active packages (pizza) during microwave heating. A microwave heat transfer model was developed by solving electromagnetic and heat transfer equations using finite element method in commercially available COMSOL Multiphysics v4.4 software. The microwave heat transfer model included detailed geometry of the cavity, phase change, and rotation of the food on the turntable. The predicted spatial surface temperature patterns and temporal profiles were validated against the experimental temperature profiles obtained using a thermal imaging camera and fiber-optic sensors. The predicted spatial surface temperature profile of different multi-component foods was in good agreement with the corresponding experimental profiles in terms of hot and cold spot patterns. The root mean square error values of temporal profiles ranged from 5.8 °C to 26.2 °C in chicken nuggets as compared 4.3 °C to 4.7 °C in mashed potatoes. In frozen lasagna, root mean square error values at six locations ranged from 6.6 °C to 20.0 °C for 6 min of heating. A microwave heat transfer model was developed to include susceptor assisted microwave heating of a

  15. Influence of flowing helium gas on plasma plume formation in atmospheric pressure plasma

    SciTech Connect

    Yambe, Kiyoyuki; Konda, Kohmei; Ogura, Kazuo

    2015-05-15

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and a foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. The helium gas flowing out of quartz tube mixes with air, and the flow channel is composed of the regions of flowing helium gas and air. The plasma plume length is equivalent to the reachable distance of flowing helium gas. Although the amount of helium gas on the flow channel increases by increasing the inner diameter of quartz tube at the same gas flow velocity, the plasma plume length peaks at around 8 m/s of gas flow velocity, which is the result that a flow of helium gas is balanced with the amount of gas. The plasma plume is formed at the boundary region where the flow of helium gas is kept to the wall of the air.

  16. 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.

  17. Atmospheric cold plasma jet for plant disease treatment

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  18. Hot electron confinement in a microwave heated spindle cusp

    NASA Astrophysics Data System (ADS)

    Prelas, M. A.

    1991-08-01

    The Plasma Research Laboratory at the University of Missouri-Columbia was established with awards from the McDonnell Douglas Foundation, ARMCO, Union Electric, Black and Vetch, Kansas City Power and Light, the National Science Foundation, and DOE. The Plasma Research Lab's major effort is the Missouri Magnetic Mirror (MMM or M(exp 3)) Project. The technical goals of MMM have been (1) Diagnostic Development, (2) Plasma Physics in the Cusp geometry, (3) plasma-wall interactions, (4) impurity effects in a steady-state plasma, and (5) Development of Diagnostics for use in harsh plasma processing environments. The other major goal of MMM has remained providing a facility for hands-on training in experimental plasma physics. The major experimental facility of MMM is the MMM Modified Experiment (M4X). Other research efforts in the Plasma Research Laboratory include small efforts in cold fusion, toroidal magnetic confinement, and inertial confinement and a potentially major effort in direct conversion of nuclear energy.

  19. Hot electron confinement in a microwave heated spindle cusp

    SciTech Connect

    Prelas, M.A.

    1991-08-01

    The Plasma Research Laboratory at the University of Missouri-Columbia was established with awards from the McDonnel Douglas Foundation, ARMCO, Union Electric, Black and Vetch, Kansas City Power and Light, the National Science Foundation, and DOE. The Plasma Research Lab's major effort is the Missouri Magnetic Mirror (MMM or M{sup 3}) Project. The technical goals of MMM have been (1) Diagnostic Development, (2) Plasma Physics in the Cusp geometry, (3) plasma-wall interactions, (4) impurity effects in a steady-state plasma, and (5) Development of Diagnostics for use in harsh plasma processing environments. The other major goal of MMM has remained providing a facility for hands-on training in experimental plasma physics. The major experimental facility of MMM is the MMM Modified Experiment (M4X). Other research efforts in the Plasma Research Laboratory include small efforts in cold fusion, toroidal magnetic confinement, and inertial confinement and a potentially major effort in direct conversion of nuclear energy.

  20. Hybrid Simulations of the Plasma Interaction with Europa's Atmosphere

    NASA Astrophysics Data System (ADS)

    Dols, V. J.; Delamere, P. A.; Wilson, R. J.; Weber, T. D.; Crary, F. J.; Bagenal, F.; Cassidy, T. A.

    2013-12-01

    Europa's atmosphere is about 100 times more tenuous than Io. The weaker ambient magnetic field and lower density of incident plasma means that the electrodynamic interaction is also weaker. Consequently, substantial fluxes of torus ions might reach the icy surface and produce radiolytic reactions. Molecular O2 is the dominant atmospheric product of this surface sputtering. Observations of oxygen UV emissions (specifically the ratio of OI 1356A / 1304A emissions) are consistent with an atmosphere that is composed predominately of O2 with a small amount (2%) of atomic O. Galileo observations along flybys close to Europa have revealed the existence of induced currents in a conducting ocean under the icy crust. They also showed that, from flyby to flyby, the plasma interaction is very variable. Asymmetries of the plasma density and temperature in the wake of Europa were also observed and still elude a clear explanation. Galileo mag data also detected ion cyclotron waves, which is an indication of heavy ion pickup close to the moon. We model the interaction between the plasma torus and Europa's atmosphere with a hybrid code, where ions are treated as kinetic particles moving under the Lorentz force and electrons as a fluid leading to a generalized formulation of Ohm's law. We prescribe an O2 atmosphere with a vertical density column consistent with UV observations and model the plasma properties along several Galileo flybys of the moon. We compare our results with the magnetometer observations, PLS electron density observations and a new re-analysis of the PLS plasma measurements (ion density, temperature and bulk flow velocity).

  1. Physics and medical applications of cold atmospheric plasma

    NASA Astrophysics Data System (ADS)

    Keidar, Michael

    2013-09-01

    Recent progress in atmospheric plasmas led to the creation of cold plasmas with ion temperature close to room temperature. Varieties of novel plasma diagnostic techniques were applied in a quest to understand physics of cold plasmas. In particular it was established that the streamer head charge is about 108 electrons, the electrical field in the head vicinity is about 107 V/m, and the electron density of the streamer column is about 1019 m3. We have demonstrated the efficacy of cold plasma in a pre-clinical model of various cancer types (lung, bladder, breast, head, neck, brain and skin). Both in-vitro andin-vivo studies revealed that cold plasmas selectively kill cancer cells. We showed that: (a) cold plasma application selectively eradicates cancer cells in vitro without damaging normal cells. (b) Significantly reduced tumor size in vivo. Cold plasma treatment led to tumor ablation with neighbouring tumors unaffected. These experiments were performed on more than 10 mice with the same outcome. We found that tumors of about 5mm in diameter were ablated after 2 min of single time plasma treatment. The two best known cold plasma effects, plasma-induced apoptosis and the decrease of cell migration velocity can have important implications in cancer treatment by localizing the affected area of the tissue and by decreasing metastasic development. In addition, cold plasma treatment has affected the cell cycle of cancer cells. In particular, cold plasmainduces a 2-fold increase in cells at the G2/M-checkpoint in both papilloma and carcinoma cells at ~24 hours after treatment, while normal epithelial cells (WTK) did not show significant differences. It was shown that reactive oxygen species metabolism and oxidative stress responsive genes are deregulated. We investigated the production of reactive oxygen species (ROS) with cold plasma treatment as a potential mechanism for the tumor ablation observed.

  2. Spectroscopic measurement of plasma gas temperature of the atmospheric-pressure microwave induced nitrogen plasma torch

    NASA Astrophysics Data System (ADS)

    Chen, Chuan-Jie; Li, Shou-Zhe

    2015-06-01

    Atmospheric-pressure microwave induced N2 plasma is diagnosed by optical emission spectroscopy with respect to the plasma gas temperature. The spectroscopic measurement of plasma gas temperature is discussed with respect to the spectral line broadening of Ar I and the various emission rotational-vibrational band systems of N2(B-A), N2(C-B) and \\text{N}2+(\\text{B-X}). It is found that the Boltzmann plot of the selective spectral lines from \\text{N}2+(\\text{B-X}) at 391.4 nm is preferable to others with an accuracy better than 5% for an atmospheric-pressure plasma of high gas temperature. On the basis of the thermal balance equation, the dependences of the plasma gas temperature on the absorbed power, the gas flow rate, and the gas composition are investigated experimentally with photographs recording the plasma morphology.

  3. Atmospheric Plasma-Enhanced Soft Hydrolysis of Southern Pine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The production of fermentable sugars from southern pine using atmospheric plasma (AP) was studied. AP processing in the dielectric barrier discharge (DBD) configuration was coupled with acid hydrolysis in an effort to determine how AP can impact a standard conversion technique. The effects of plas...

  4. ANNUAL REPORT. ATMOSPHERIC-PRESSURE PLASMA CLEANING OF CONTAMINATED SURFACES

    EPA Science Inventory

    The objective of this work is to demonstrate a practical, atmospheric pressure plasma tool for the surface decontamination of nuclear waste. Decontamination of radioactive materials that have accumulated on the surfaces of equipment and structures is a challenging and costly unde...

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  6. Use of Cold Atmospheric Plasma to Detoxify Hazelnuts from Aflatoxins

    PubMed Central

    Siciliano, Ilenia; Spadaro, Davide; Prelle, Ambra; Vallauri, Dario; Cavallero, Maria Chiara; Garibaldi, Angelo; Gullino, Maria Lodovica

    2016-01-01

    Aflatoxins, produced by Aspergillus flavus and A. parasiticus, can contaminate different foodstuffs, such as nuts. Cold atmospheric pressure plasma has the potential to be used for mycotoxin detoxification. In this study, the operating parameters of cold atmospheric pressure plasma were optimized to reduce the presence of aflatoxins on dehulled hazelnuts. First, the effect of different gases was tested (N2, 0.1% O2 and 1% O2, 21% O2), then power (400, 700, 1000, 1150 W) and exposure time (1, 2, 4, and 12 min) were optimized. In preliminary tests on aflatoxin standard solutions, this method allowed to obtain a complete detoxification using a high power for a few minutes. On hazelnuts, in similar conditions (1000 W, 12 min), a reduction in the concentration of total aflatoxins and AFB1 of over 70% was obtained. Aflatoxins B1 and G1 were more sensitive to plasma treatments compared to aflatoxins B2 and G2, respectively. Under plasma treatment, aflatoxin B1 was more sensitive compared to aflatoxin G1. At the highest power, and for the longest time, the maximum temperature increment was 28.9 °C. Cold atmospheric plasma has the potential to be a promising method for aflatoxin detoxification on food, because it is effective and it could help to maintain the organoleptic characteristics. PMID:27128939

  7. Use of Cold Atmospheric Plasma to Detoxify Hazelnuts from Aflatoxins.

    PubMed

    Siciliano, Ilenia; Spadaro, Davide; Prelle, Ambra; Vallauri, Dario; Cavallero, Maria Chiara; Garibaldi, Angelo; Gullino, Maria Lodovica

    2016-01-01

    Aflatoxins, produced by Aspergillus flavus and A. parasiticus, can contaminate different foodstuffs, such as nuts. Cold atmospheric pressure plasma has the potential to be used for mycotoxin detoxification. In this study, the operating parameters of cold atmospheric pressure plasma were optimized to reduce the presence of aflatoxins on dehulled hazelnuts. First, the effect of different gases was tested (N₂, 0.1% O₂ and 1% O₂, 21% O₂), then power (400, 700, 1000, 1150 W) and exposure time (1, 2, 4, and 12 min) were optimized. In preliminary tests on aflatoxin standard solutions, this method allowed to obtain a complete detoxification using a high power for a few minutes. On hazelnuts, in similar conditions (1000 W, 12 min), a reduction in the concentration of total aflatoxins and AFB₁ of over 70% was obtained. Aflatoxins B₁ and G₁ were more sensitive to plasma treatments compared to aflatoxins B₂ and G₂, respectively. Under plasma treatment, aflatoxin B₁ was more sensitive compared to aflatoxin G₁. At the highest power, and for the longest time, the maximum temperature increment was 28.9 °C. Cold atmospheric plasma has the potential to be a promising method for aflatoxin detoxification on food, because it is effective and it could help to maintain the organoleptic characteristics. PMID:27128939

  8. Cold atmospheric plasma sterilization: from bacteria to biomolecules

    NASA Astrophysics Data System (ADS)

    Kong, Michael

    2009-10-01

    Although ionized gases have been known to have biological effects for more than 100 years, their impact on the practice in healthcare service became very significant only recently. Today, plasma-based surgical tools are used for tissue reduction and blood coagulation as surgical procedures. Most significant however is the speed at which low-temperature gas plasmas are finding new applications in medicine and biology, including plasma sterilization, wound healing, and cancer therapies just to name a few. In the terminology of biotechnology, the ``pipeline'' is long and exciting. This presentation reviews the current status of the field with a particular emphasis on plasma inactivation of microorganisms and biomolecules, for which comprehensive scientific evidence has been obtained. Some of the early speculations of biocidal plasma species are now being confirmed through a combination of optical emission spectroscopy, laser-induced fluorescence, mass spectrometry, fluid simulation and biological sensing with mutated bacteria. Similarly, fundamental studies are being performed to examine cell components targeted by gas plasmas, from membrane, through lipid and membrane proteins, to DNA. Scientific challenge is significant, as the usual complexity of plasma dynamics and plasma chemistry is compounded by the added complication that cells are live and constantly evolving. Nevertheless, the current understanding of plasma inactivation currently provides strong momentum for plasma decontamination technologies to be realized in healthcare. We will discuss the issue of protein and tissue contaminations of surgical instruments and how cold atmospheric plasmas may be used to degrade and reduce their surface load. In the context of plasma interaction with biomolecules, we will consider recent data of plasma degradation of adhesion proteins of melanoma cells. These adhesion proteins are important for cancer cell migration and spread. If low-temperature plasmas could be used to

  9. Surface analysis of polymers treated by remote atmospheric pressure plasma.

    PubMed

    Gonzalez, Eleazar; Hicks, Robert F

    2010-03-01

    The surfaces of high-density polyethylene (HDPE), poly(methyl methacrylate) (PMMA), and polyethersulfone (PES) were treated with a low-temperature, atmospheric pressure oxygen and helium plasma. The polymers were exposed to the downstream afterglow of the plasma, which contained primarily oxygen atoms and metastable oxygen molecules ((1)Delta(g) O(2)), and no ions or electrons. X-ray photoelectron spectroscopy (XPS) of HDPE revealed that 20% of the carbon atoms were converted into oxidized functional groups, with about half of these being carboxylic acids. Attenuated total reflection infrared spectroscopy of all three polymers was obtained in order to determine the types of functional groups formed by atmospheric plasma exposure. It was found that the polymers were rapidly oxidized with addition of alcohols, ketones, and carboxylic acids to the carbon backbone. Chain scission occurred on HDPE and PMMA, while on PES the aromatic groups underwent ring-opening and insertion of carboxylic acid. PMID:19950952

  10. Application of atmospheric pressure plasma in polymer and composite adhesion

    NASA Astrophysics Data System (ADS)

    Yu, Hang

    An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The temperature of the plasm gas reaching the surface of the substrate did not exceed 150 °C, which makes it suitable for polymer processing. The reactive species in the plasma downstream includes ~ 1016-1017 cm-3 atomic oxygen, ~ 1015 cm-3 ozone molecule, and ~ 10 16 cm-3 metastable oxygen molecule (O2 1Deltag). The substrates were treated at 2-5 mm distance from the exit of the plasma. Surface properties of the substrates were characterized using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the plasma treated samples were bonded adhesively or fabricated into composites. The increase in mechanical strength was correlated to changes in the material composition and structure after plasma treatment. The work presented hereafter establishes atmospheric pressure plasma as an effective method to activate and to clean the surfaces of polymers and composites for bonding. This application can be further expanded to the activation of carbon fibers for better fiber-resin interactions during the fabrication of composites. Treating electronic grade FR-4 and polyimide with the He/O2 plasma for a few seconds changed the substrate surface from hydrophobic to hydrophilic, which allowed complete wetting of the surface by epoxy in underfill applications. Characterization of the surface by X-ray photoelectron spectroscopy shows formation of oxygenated functional groups, including hydroxyl, carbonyl, and

  11. Plasma-ion-induced Sputtering And Heating Of Titan'S Atmosphere

    NASA Astrophysics Data System (ADS)

    Tucker, Orenthal J.

    2006-09-01

    Plasma-ion-induced sputtering and heating of Titan's atmosphere O.J. Tucker (1), R.E. Johnson (1), M. Michael (1), V.I. Shematovich (1,2) J.H. Luhmann (3), S.A. Ledvina (3) (1) University of Virginia, Charlottesville, VA 22904, USA (2) Institute of Astronomy RAS, Moscow 109017, Russia, (3) University of California, Berkeley, CA 94720, USA Titan is unique among the outer solar system icy satellites in having an atmosphere with a column density about ten times that of the Earth's atmosphere. Atmospheres equivalent in size similar to that at Titan would have been removed from the icy Galilean satellites by the plasma trapped in the Jovian magnetosphere (Johnson 2004). In this paper we describe the deposition of energy, the erosion and the expansion of the upper atmosphere of Titan using Direct Simulation Monte Carlo models (Shematovich et al. 2003; Michael et al. 2005). These calculations are used to calibrate semi-empirical models of atmospheric sputtering (Johnson 1994) that can be employed in interpreting Cassini data at Titan. It is shown that the globally averaged flux of magnetospheric and pickup ions deposit more energy in Titan's upper atmosphere than solar radiation. Using a number of plasma conditions, the temperature and density vs. altitude above the exobase and the rate of escape are calculated and compared to available Cassini data. References: Johnson, R.E. "Plasma-induced Sputtering of an Atmosphere" in Space Science Reviews 69 215-253 (1994). Johnson. R.E., “ The magnetospheric plasma-driven evolution of satellite atmospheres” Astrophys. J. 609, L99-L102 (2004). Michael M., R.E. Johnson, F. Leblanc, M. Liu, J.G. Luhmann, and V.I. Shematovich, "Ejection of nitrogen from Titan's atmosphere by magnetospheric ions and pick-up ions", Icarus 175, 263-267 (2005). Shematovich, V.I., R.E. Johnson, M. Michael, and J.G. Luhmann,"Nitrogen loss from Titan", JGR 108, No. E8, 5087, doi:10.1029/2003JE002094 (2003). 1

  12. Ion Chemistry in Atmospheric and Astrophysical Plasmas

    NASA Technical Reports Server (NTRS)

    Dalgarno, A.; Fox, J. L.

    1994-01-01

    There are many differences and also remarkable similarities between the ion chemistry and physics of planetary ionospheres and the ion chemistry and physics of astronomical environments beyond the solar system. In the early Universe, an expanded cooling gas of hydrogen and helium was embedded in the cosmic background radiation field and ionized by it. As the Universe cooled by adiabatic expansion, recombination occurred and molecular formation was driven by catalytic reactions involving the relict electrons and protons. Similar chemical processes are effective in the ionized zones of gaseous and planetary nebulae and in stellar winds where the ionization is due to radiation from the central stars, in the envelopes of supernovae where the ionization is initiated by the deposition of gamma-rays, in dissociative shocks where the ionization arises from electron impacts in a hot gas and in quasar broad-line region clouds where the quasar is responsible for the ionization. At high altitudes in the atmospheres of the Jovian planets, the main constituents are hydrogen and helium and the ion chemistry and physics is determined by the same processes, the source of the ionization being solar ultraviolet radiation and cosmic rays. After the collapse of the first distinct astronomical entities to emerge from the uniform flow, heavy elements were created by nuclear burning in the cores of the collapsed objects and distributed throughout the Universe by winds and explosions. The chemistry and physics became more complicated. Over 90 distinct molecular species have been identified in interstellar clouds where they are ionized globally by cosmic ray impacts and locally by radiation and shocks associated with star formation and evolution. Complex molecules have also been found in circumstellar shells of evolved stars. At intermediate and low altitudes in the Jovian atmospheres, the ion chemistry is complicated by the increasing abundance of heavy elements such as carbon, and an

  13. Effects of microwave heating on porous structure of regenerated powdered activated carbon used in xylose.

    PubMed

    Li, Wei; Wang, Xinying; Peng, Jinhui

    2014-01-01

    The regeneration of spent powdered activated carbons used in xylose decolourization by microwave heating was investigated. Effects of microwave power and microwave heating time on the adsorption capacity of regenerated activated carbons were evaluated. The optimum conditions obtained are as follows: microwave power 800W; microwave heating time 30min. Regenerated activated carbon in this work has high adsorption capacities for the amount of methylene blue of 16 cm3/0.1 g and the iodine number of 1000.06mg/g. The specific surface areas of fresh commercial activated carbon, spent carbon and regenerated activated carbon were calculated according to the Brunauer, Emmett and Teller method, and the pore-size distributions of these carbons were characterized by non-local density functional theory (NLDFT). The results show that the specific surface area and the total pore volume of regenerated activated carbon are 1064 m2/g and 1.181 mL/g, respectively, indicating the feasibility of regeneration of spent powdered activated carbon used in xylose decolourization by microwave heating. The results of surface fractal dimensions also confirm the results of isotherms and NLDFT. PMID:24645431

  14. Microwave heating: Industrial applications. (Latest citations from the EI Compendex*plus database). Published Search

    SciTech Connect

    1996-04-01

    The bibliography contains citations concerning industrial uses and design of microwave heating equipment. Citations discuss applications in food processing, industrial heating, vulcanization, textile finishing, metallurgical sintering, ceramic manufacturing, paper industries, and curing of polymers. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  15. Microwave heating: Industrial applications. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1995-12-01

    The bibliography contains citations concerning industrial uses and design of microwave heating equipment. Included are heating and drying of paper, industrial process heat, vulcanization, textile processing, metallurgical heat for sintering and ceramic manufacturing, food processing, and curing of polymers.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  16. A New Automated Microwave Heating Process for Cooking and Pasteurization of Microwaveable Foods Containing Raw Meats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new microwave heating process was developed for cooking microwaveable foods containing raw meats. A commercially available inverter-based microwave oven was modified for pasteurization of mechanically tenderized beef, inoculated with Escherichia coli O157:H7 (~ 5 log cfu/g) and packaged in a 12 o...

  17. Apparatus with moderating material for microwave heat treatment of manufactured components

    DOEpatents

    Ripley, Edward B.

    2011-05-10

    An apparatus for heat treating manufactured components using microwave energy and microwave susceptor material. Heat treating medium such as eutectic salts may be employed. A fluidized bed introduces process gases which may include carburizing or nitriding gases The process may be operated in a batch mode or continuous process mode. A microwave heating probe may be used to restart a frozen eutectic salt bath.

  18. Comparison of glycation in conventionally and microwave-heated ovalbumin by high resolution mass spectrometry.

    PubMed

    Wang, Hui; Tu, Zong-Cai; Liu, Guang-Xian; Liu, Cheng-Mei; Huang, Xiao-Qin; Xiao, Hui

    2013-11-15

    The glycation extent of ovalbumin under two heating conditions, conventional and microwave heating was monitored by high resolution mass spectrometry, following pepsin digestion. The sequence coverage of the unglycated and glycated ovalbumin was 100% and 95%, respectively. About 35.2% of the lysines after microwave heating and 40.8% of the lysines after conventional heating were modified by d-glucose. The glycation content increased quickly when ovalbumin-glucose mixture was incubated for 15min, under both processing conditions. These modifications were slowed down after 30min of heating and no obvious advanced stage products were observed. The glycated peptides exhibited varying degrees of glycation, under both conventional and microwave heating, suggesting that glycation is strongly relevant to the protein structure. The fact that some peptides showed a lower level of glycation when heated by microwave indicated that microwave radiation might be a non-thermal process. In addition, the lack of browning after microwave heating emphasised the difference between microwave and conventional heating. PMID:23790877

  19. Combined chromatographic and mass spectrometric toolbox for fingerprinting migration from PET tray during microwave heating.

    PubMed

    Alin, Jonas; Hakkarainen, Minna

    2013-02-13

    A combined chromatographic and mass spectrometric toolbox was utilized to determine the interactions between poly(ethylene terephthalate) (PET) food packaging and different food simulants during microwave heating. Overall and specific migration was determined by combining weight loss measurements with gas chromatography-mass spectrometry (GC-MS) and electrospray ionization mass spectrometry (ESI-MS). This allowed mapping of low molecular weight migrants in the molecular range up to 2000 g/mol. Microwave heating caused significantly faster migration of cyclic oligomers into ethanol and isooctane as compared to migration during conventional heating at the same temperature. This effect was more significant at lower temperature at which diffusion rates are generally lower. It was also shown that transesterification took place between PET and ethanol during microwave heating, leading to formation of diethyl terephthalate. The detected migrants included cyclic oligomers from dimer to hexamer, in most cases containing extra ethylene glycol units, and oxidized Irgafos 168. ESI-MS combined with CID MS-MS was an excellent tool for structural interpretation of the nonvolatile compounds migrating to the food simulants. The overall migration was below the overall migration limit of 10 mg/dm(2) set by the European commission after 4 h of microwave heating at 100 °C in all studied food simulants. PMID:23343184

  20. Sustainable synthesis of chemical entities by microwave heating with nano-catalysis in water

    EPA Science Inventory

    •Sustainable synthesis of chemical entities by microwave heating with nano-catalysis in water •CRADA’s with the private companies, CEM corporation and VeruTEK Technologies •Green Chemistry principles are accommodated via multi-faceted approach. Learning from nature- using na...

  1. Durable Nanolayer Graft Polymerization of Functional Finishes Using Atmospheric Plasma

    NASA Astrophysics Data System (ADS)

    Mazloumpour, Maryam

    Various applications of atmospheric pressure plasma were investigated in conjunction with different chemistries on nonwoven materials including spunbond polyester (PET) and spunbod polypropylene for fuel separation and antimicrobial functionalities. Hydrophobic/Oleophobic properties were conferred on nonwoven polyester (PET) via plasma-induced graft polymerization of different hydrophobic non-C8 perfluorocarbon chemistry including perfluorohexylethylmethacrylate, perfluorohexylethylacrylate, allylpentafluorobenzene, pentafluorostyrene, or 1,3-divinyltetramethyldisiloxane in the vapor form using both in-situ and down-stream plasma configurations. Different nanolayers of the grafted polymer were furnished on nonwovens to generate surfaces with different level of wettabilities for medical applications and water/fuel separation. The effect of various hydrophobic chemistry, different plasma conditions, and plasma device parameters including plasma power and plasma exposure time were studied and the performance was characterized by measuring the contact angle and the wettability rating against liquids with broad range of surface tensions. Vapor deposition of 2-(perfluorohexyl)ethyl methacrylate and pentafluorostyrene on nonwoven PET followed by plasma-induced graft polymerization was investigated for possible use in water/fuel separation. Different nanolayer thicknesses (80-180nm) of the grafted polymer were achieved to generate surfaces with different wettabilities for water/fuel separation of different fuel compositions. The effect of different plasma conditions and device parameters including the flow rate of monomers, power of the device, and time of plasma exposure on the separation of different fuels was studied and characterized by measuring the surface energy of the treated substrates. The surface chemistry and morphology of the treated samples were characterized using XPS, SEM and TOF-SIMS techniques which confirmed the grafting of monomer onto the substrate

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

    PubMed

    Motrescu, Iuliana; Nagatsu, Masaaki

    2016-05-18

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

  3. Atmospheric Pressure RF Plasma Electrical and Optical Characteristics

    NASA Astrophysics Data System (ADS)

    Gulec, Ali; Oksuz, Lutfi; Hershkowitz, Noah

    2009-10-01

    An atmospheric pressure 13.56 MHz RF source is used for plasma polymerization, nanocomposite deposition and for sterilization purposes. The air discharge electrical and optical characteristics are measured using monochromator and electrical probes. The addition of helium flow to the RF discharge system allows production of stable glow plasma discharge. The electron temperature and plasma densities are estimated using the emission lines of HeI and double probes. Emission of the He+air atmospheric pressure plasma is observed from the OH radical, several lines of the N2, N2^+ and atomic O, H and He lines. He flow rate and applied rf voltage affect on these emission spectra are investigated and the spectral lines are used for calculation of plasma parameters. Plasma electron temperature is calculated using HeI lines and compared with double probe data. The OI 777 and Hα 656 lines are also investigated by varying the applied voltage and He flow rate. The calculated electron temperature was approximately 0.2 eV and dependent on the He flow rate and applied power.

  4. 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.

  5. Plasma polymerization of acrylic acid onto polystyrene by cyclonic plasma at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Chang, Yi-Jan; Lin, Chin-Ho; Huang, Chun

    2016-01-01

    The cyclonic atmospheric-pressure plasma is developed for chamberless deposition of poly(acrylic acid) film from argon/acrylic acid mixtures. The photoemission plasma species in atmospheric-pressure plasma polymerization was identified by optical emission spectroscopy (OES). The OES diagnosis data and deposition results indicated that in glow discharge, the CH and C2 species resulted from low-energy electron-impact dissociation that creates deposition species, but the strong CO emission lines are related to nondeposition species. The acrylic acid flow rate is seen as the key factor affecting the film growth. The film surface analysis results indicate that a smooth, continuous, and uniform surface of poly(acrylic acid) films can be formed at a relatively low plasma power input. This study reveals the potential of chamberless film growth at atmospheric pressure for large-area deposition of poly(acrylic acid) films.

  6. Reactivity zones around an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Birer, Özgür

    2015-11-01

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

  7. Atmospheric pressure plasma treatment of flat aluminum surface

    NASA Astrophysics Data System (ADS)

    Bónová, Lucia; Zahoranová, Anna; Kováčik, Dušan; Zahoran, Miroslav; Mičušík, Matej; Černák, Mirko

    2015-03-01

    The atmospheric pressure ambient air and oxygen plasma treatment of flat aluminum sheets using the so-called Diffuse Coplanar Surface Barrier Discharge (DCSBD) were investigated. The main objective of this study is to show the possibility of using DCSBD plasma source to activate and clean aluminum surface. Surface free energy measurements, X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM/EDX) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) were used for the characterization of the aluminum surface chemistry and changes induced by plasma treatment. Short plasma exposure times (several seconds) led to a significant increase in the surface free energy due to changes of its polar components. Various ageing effects, depending on the storage conditions were observed and discussed. Effects of air and oxygen plasmas on the removal of varying degrees of artificial hydrocarbon contamination of aluminum surfaces were investigated by the means of EDX, ATR-FTIR and XPS methods. A significant decrease in the carbon surface content after the plasma treatment indicates a strong plasma cleaning effect, which together with high energy efficiency of the DCSBD plasma source points to potential benefits of DCSBD application in processing of the flat aluminum surfaces.

  8. Using atmospheric pressure plasma treatment for treating grey cotton fabric.

    PubMed

    Kan, Chi-Wai; Lam, Chui-Fung; Chan, Chee-Kooi; Ng, Sun-Pui

    2014-02-15

    Conventional wet treatment, desizing, scouring and bleaching, for grey cotton fabric involves the use of high water, chemical and energy consumption which may not be considered as a clean process. This study aims to investigate the efficiency of the atmospheric pressure plasma (APP) treatment on treating grey cotton fabric when compared with the conventional wet treatment. Grey cotton fabrics were treated with different combinations of plasma parameters with helium and oxygen gases and also through conventional desizing, scouring and bleaching processes in order to obtain comparable results. The results obtained from wicking and water drop tests showed that wettability of grey cotton fabrics was greatly improved after plasma treatment and yielded better results than conventional desizing and scouring. The weight reduction of plasma treated grey cotton fabrics revealed that plasma treatment can help remove sizing materials and impurities. Chemical and morphological changes in plasma treated samples were analysed by FTIR and SEM, respectively. Finally, dyeability of the plasma treated and conventional wet treated grey cotton fabrics was compared and the results showed that similar dyeing results were obtained. This can prove that plasma treatment would be another choice for treating grey cotton fabrics. PMID:24507269

  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. PLASMOSE - antimicrobial effects of modular atmospheric plasma sources

    PubMed Central

    Ehlbeck, Jörg; Brandenburg, Ronny; von Woedtke, Thomas; Krohmann, Udo; Stieber, Manfred; Weltmann, Klaus-Dieter

    2008-01-01

    The technological potential of non-thermal plasmas for the antimicrobial treatment of heat sensitive materials is well known and has been documented in a great number of research activities, but the realisation of industrial plasma-based decontamination processes remains a great challenge. One of the reasons for this situation is the fact that an antimicrobial treatment process needs to consider all properties of the product to be treated as well as the requirements of the complete procedure, e.g. a reprocessing of a medical instrument. The aim of the BMBF-funded network project PLASMOSE is to demonstrate the applicability of plasma-based processes for the antimicrobial treatment on selected, heat sensitive products. Modular and selective plasma sources, driven at atmospheric pressure are used. This basic approach shall combine the technological advantages of atmospheric pressure plasmas (avoidance of vacuum devices and batch processing) with the flexibility and handling properties of modular devices. Two different objectives were selected: the outer surface treatment of medical products and the treatment of hollow packaging for pharmaceutical products. The outer surface treatment of medical products, in particular catheters for intracardial electrophysiological studies, is investigated by means of RF-driven plasma jets in argon. Due to its compact design they are predestined for modularisation and can be adapted to nearly any complex 3-dimensional structure as given by the medical products. The realisation of an antimicrobial treatment process of hollow packaging for pharmaceutical products has quite different demands. Such a process is needed to be implemented in in-line filling procedures and to work without additional process gases. The idea is to use an atmospheric air, microwave-driven self propagating discharge. The plasma process is optimized for the decontamination of 200 ml bottles by field simulation studies combined with optical emissions spectroscopy

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

    NASA Astrophysics Data System (ADS)

    Tomita, Kentaro

    2015-09-01

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

  12. Plasma Disinfection and the Deterioration of Surgical Tools at Atmospheric Pressure Plasma

    NASA Astrophysics Data System (ADS)

    Zaaba, Siti Khadijah; Akitsu, Tetsuya; Ohkawa, Hiroshi; Katayama-Hirayama, Keiko; Tsuji, Masao; Shimizu, Naohiro; Imanishi, Yuichirou

    The purpose of this paper is to present and compare disinfection effect of plasma by means of Atmospheric Pressure Glow plasma and streamer discharge. Geobacillus stearothermophilus was used as biological indicator for disinfection process. The effect of blades after irradiated in plasma was also studied by SEM analysis. It was found that the disinfection process was effective when the cylindrical configuration was applied. Carbon steel blade was also found to be deteriorated after immersed in plasma irradiation. Results indicate that disinfection can be achieved and at the same time deteriorations of the tools were observed.

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

    SciTech Connect

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

    2010-05-15

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

  14. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Zhu, Fengsen; Tu, Xin; Bo, Zheng; Cen, Kefa; Li, Xiaodong

    2016-05-01

    In this work, a novel direct current (DC) atmospheric pressure rotating gliding arc (RGA) plasma reactor has been developed for plasma-assisted chemical reactions. The influence of the gas composition and the gas flow rate on the arc dynamic behaviour and the formation of reactive species in the N2 and air gliding arc plasmas has been investigated by means of electrical signals, high speed photography, and optical emission spectroscopic diagnostics. Compared to conventional gliding arc reactors with knife-shaped electrodes which generally require a high flow rate (e.g., 10–20 L/min) to maintain a long arc length and reasonable plasma discharge zone, in this RGA system, a lower gas flow rate (e.g., 2 L/min) can also generate a larger effective plasma reaction zone with a longer arc length for chemical reactions. Two different motion patterns can be clearly observed in the N2 and air RGA plasmas. The time-resolved arc voltage signals show that three different arc dynamic modes, the arc restrike mode, takeover mode, and combined modes, can be clearly identified in the RGA plasmas. The occurrence of different motion and arc dynamic modes is strongly dependent on the composition of the working gas and gas flow rate. supported by National Natural Science Foundation of China (No. 51576174), the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20120101110099) and the Fundamental Research Funds for the Central Universities (No. 2015FZA4011)

  15. Pulsed, atmospheric pressure plasma source for emission spectrometry

    DOEpatents

    Duan, Yixiang; Jin, Zhe; Su, Yongxuan

    2004-05-11

    A low-power, plasma source-based, portable molecular light emission generator/detector employing an atmospheric pressure pulsed-plasma for molecular fragmentation and excitation is described. The average power required for the operation of the plasma is between 0.02 W and 5 W. The features of the optical emission spectra obtained with the pulsed plasma source are significantly different from those obtained with direct current (dc) discharge higher power; for example, strong CH emission at 431.2 nm which is only weakly observed with dc plasma sources was observed, and the intense CN emission observed at 383-388 nm using dc plasma sources was weak in most cases. Strong CN emission was only observed using the present apparatus when compounds containing nitrogen, such as aniline were employed as samples. The present apparatus detects dimethylsulfoxide at 200 ppb using helium as the plasma gas by observing the emission band of the CH radical. When coupled with a gas chromatograph for separating components present in a sample to be analyzed, the present invention provides an apparatus for detecting the arrival of a particular component in the sample at the end of the chromatographic column and the identity thereof.

  16. Cold Atmospheric Plasma Technology for Decontamination of Space Equipment

    NASA Astrophysics Data System (ADS)

    Thomas, Hubertus; Rettberg, Petra; Shimizu, Tetsuji; Thoma, Markus; Morfill, Gregor; Zimmermann, Julia; Müller, Meike; Semenov, Igor

    2016-07-01

    Cold atmospheric plasma (CAP) technology is very fast and effective in inactivation of all kinds of pathogens. It is used in hygiene and especially in medicine, since the plasma treatment can be applied to sensitive surfaces, like skin, too. In a first study to use CAP for the decontamination of space equipment we could show its potential as a quite promising alternative to the standard "dry heat" and H2O2 methods [Shimizu et al. Planetary and Space Science, 90, 60-71. (2014)]. In a follow-on study we continue the investigations to reach high application level of the technology. First, we redesign the actual setup to a plasma-gas circulation system, increasing the effectivity of inactivation and the sustainability. Additionally, we want to learn more about the plasma chemistry processes involved in the inactivation. Therefore, we perform detailed plasma and gas measurements and compare them to numerical simulations. The latter will finally be used to scale the decontamination system to sizes useful also for larger space equipment. Typical materials relevant for space equipment will be tested and investigated on surface material changes due to the plasma treatment. Additionally, it is planned to use electronic boards and compare their functionality before and after the CAP expose. We will give an overview on the status of the plasma decontamination project funded by the Bavarian Ministry of Economics.

  17. Compact atmospheric pressure plasma self-resonant drive circuits

    NASA Astrophysics Data System (ADS)

    Law, V. J.; Anghel, S. D.

    2012-02-01

    This paper reports on compact solid-state self-resonant drive circuits that are specifically designed to drive an atmospheric pressure plasma jet and a parallel-plate dielectric barrier discharge of small volume (0.5 cm3). The atmospheric pressure plasma (APP) device can be operated with helium, argon or a mixture of both. Equivalent electrical models of the self-resonant drive circuits and discharge are developed and used to estimate the plasma impedance, plasma power density, current density or electron number density of three APP devices. These parameters and the kinetic gas temperature are dependent on the self-resonant frequency of the APP device. For a fixed switching frequency and APP device geometry, the plasma parameters are controlled by adjusting the dc voltage at the primary coil and the gas flow rate. The resonant frequency is controlled by the selection of the switching power transistor and means of step-up voltage transformation (ferrite core, flyback transformer, or Tesla coil). The flyback transformer operates in the tens of kHz, the ferrite core in the hundreds of kHz and Tesla coil in the MHz range. Embedded within this work is the principle of frequency pulling which is exemplified in the flyback transformer circuit that utilizes a pickup coil for feedback control of the switching frequency.

  18. Plasma printing: patterned surface functionalisation and coating at atmospheric pressure.

    PubMed

    Penache, C; Gessner, C; Betker, T; Bartels, V; Hollaender, A; Klages, C-P

    2004-08-01

    A new plasma-based micropatterning technique, here referred to as plasma printing, combines the well known advantages given by the nonequilibrium character of a dielectric barrier discharge (DBD) and its operation inside small gas volumes with dimension between tens and hundreds of micrometres. The discharge is run at atmospheric pressure and can be easily implemented for patterned surface treatment with applications in biotechnology and microtechnology. In this work the local modification of dielectric substrates, e.g. polymeric films, is addressed with respect to coating and chemical functionalisation, immobilisation of biomolecules and area-selective electroless plating. PMID:16475858

  19. Cold atmospheric pressure air plasma jet for medical applications

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

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

  20. The State of the Plasma Sheet and Atmosphere at Europa

    NASA Astrophysics Data System (ADS)

    Shemansky, D. E.; Yung, Y. L.; Liu, X.; Yoshii, J.; Hansen, C. J.; Hendrix, A.; Esposito, L. W.

    2014-12-01

    The Hall et al. (1995) report announcing the discovery of atomic oxygen FUV emission from Europa included a conclusion that the atmosphere was dominated by O2. Over the following 20 years publications referencing the atmosphere accepted this conclusion, and calculations of rates, particularly mass loading of the magnetosphere depended on a composition that was of order 90% O2. Analysis of the Europa emission spectrum in the present work, leads to the conclusion that the O I emission properties were misinterpreted. The interpretation of the source process depends on the ratio of the O I 1356 and 1304 A multiplet emissions (R(4:5) = (I(1356)/I(1304)). The value of R(4:5) never reaches the lower limit for electron impact dissociation of O2 for any of the 7 recorded disk averaged measurements between 1994 and 2013. Analysis of the Cassini UVIS exposures show the 1304 A multiplet to be optically thick, and the emissions are modeled as direct electron and solar photon excitation of O I. The result is a model atmosphere dominated by O I and O II, with neutral density a factor of 100 below the original O2 model. Other considerations show incompatibility with an O2 atmosphere. Deep exposures using the Cassini UVIS EUV spectrograph provide the state of the plasma sheet at Europa. The ion species are identified as mainly outwardly diffused mass from the Io plasma torus with a minor contribution from Europa. Plasma time-constants are of the order of 200 days. Neutral species in the plasma sheet are not measureable. The energy flux in the magnetosphere L-shells are mainly responsible for energy deposition maintaining the plasma sheet. The energy content in the Io and Europa L-shells, as measured, is similar, but the mean radiative cooling rate in the Io plasma torus at the time of the Cassini encounter was 565 femtoergs cm-3 s-1, compared to 7.3 at Europa, reflecting the difference between an active and inactive planetary satellite, particularly considering the fact that most

  1. The main properties of microwave argon plasma at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Benova, E.; Pencheva, M.

    2010-01-01

    Plasma torch sustained by surface wave at atmospheric pressure is theoretically studied by means of 1D model. A steady-state Boltzmann equation in an effective field approximation coupled with a collisional-radiative model for high-pressure argon discharge is numerically solved together with Maxwell's equations for an azimuthally symmetric TM surface wave. The axial dependences of the electrons, excited atoms, atomic and molecular ions densities as well as the electron temperature, the mean power per electron and the effective electron-neutral collision frequency are determined. A strong dependence of the plasma properties on the discharge conditions and the gas temperature is obtained.

  2. Plasma-induced Escape and Alterations of Planetary Atmospheres

    NASA Astrophysics Data System (ADS)

    Johnson, R. E.; Tucker, O. J.; Ewrin, J.; Cassidy, T. A.; Leblanc, F.

    2009-12-01

    The atmospheres of planets and planetary satellites are typically imbedded in space plasmas. Depending on the interaction with the induced or intrinsic fields energetic ions can have access to the thermosphere and the corona affecting their composition and thermal structure and causing loss to space. These processes are often lumped together as ‘atmospheric sputtering’ (Johnson 1994). In this talk I will review the results of simulations of the plasma bombardment at a number of solar system bodies and use those data to describe the effect on the upper atmosphere and on escape. Of considerable recent interest is the modeling of escape from Titan. Prior to Cassini’s tour of the Saturnian system, plasma-induced escape was suggested to be the dominant loss process, but recent models of enhanced thermal escape, often referred to as ‘slow hydrodynamic’ escape, have been suggested to lead to much larger Titan atmospheric loss rates (Strobel 2008; Cui et al. 2008). Such a process has been suggested to be active at some point in time on a number of solar system bodies. I will present hybrid fluid/ kinetic models of the upper atmosphere of certain bodies in order to test both the plasma-induced and thermal escape processes. Preliminary results suggest that the loss rates estimated using the ‘slow hydrodynamic’ escape process can be orders of magnitude too large. The implications for Mars, Titan and Pluto will be discussed. Background for this talk is contained in the following papers (Johnson 2004; 2009; Chaufray et al. 2007; Johnson et al. 2008; 2009; Tucker and Johnson 2009). References: Chaufray, J.Y., R. Modolo, F. Leblanc, G. Chanteur, R.E. Johnson, and J.G. Luhmann, Mars Solar Wind interaction: formation of the Martian corona and atmosphric loss to space, JGR 112, E09009, doi:10.1029/2007JE002915 (2007) Cui, J., Yelle, R. V., Volk, K. Distribution and escape of molecular hydrogen in Titan's thermosphere and exosphere. J. Geophys. Res. 113, doi:10

  3. Io: IUE observations of its atmosphere and the plasma torus

    NASA Technical Reports Server (NTRS)

    Ballester, G. E.; Moos, H. W.; Feldman, P. D.; Strobel, D. F.; Skinner, T. E.; Bertaux, J.-L.; Festou, M. C.

    1988-01-01

    Two of the main components of the atmosphere of Io, neutral oxygen and sulfur, were detected with the IUE. Four observations yield brightnesses that are similar, regardless of whether the upstream or the downstream sides of the torus plasma flow around Io is observed. A simple model requires the emissions to be produced by the interaction of O and S columns in the exospheric range with 2 eV electrons. Cooling of the 5 eV torus electrons is required prior to their interaction with the atmosphere of Io. Inconsistencies in the characteristics of the spectra that cannot be accounted for in this model require further analysis with improved atomic data. The Io plasma torus was monitored with the IUE. The long-term stability of the warm torus is established. The observed brightnesses were analyzed using a model of the torus, and variations of less than 30 percent in the composition are observed, the quantitative results being model dependent.

  4. Atmospheric-pressure plasma synthesis of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Nozaki, Tomohiro; Yoshida, Shinpei; Karatsu, Takuya; Okazaki, Ken

    2011-05-01

    An atmospheric-pressure radio-frequency discharge (APRFD) has great advantages over vacuum-oriented plasma-enhanced chemical vapour deposition (PECVD) as well as other types of atmospheric-pressure plasma sources in terms of single-walled carbon nanotube (SWCNT) growth. We first provide an overview on the recent advances in PECVD synthesis of CNTs, ranging from low pressure to atmospheric pressure, and then we present our current work focusing on the analysis of reactive species generated in the cathodic plasma sheath for further understanding of the SWCNT growth mechanism in PECVD. It was found that the plasma-generated C2H2 is the main CNT growth precursor in PECVD. Approximately 30% of the CH4 (initial feedstock) was converted into C2H6, C2H4 and C2H2. A trace amount of C2H2 enabled the synthesis of SWCNTs in the thermal chemical vapour deposition (CVD) regime. H2 is necessary to grow SWCNTs using PECVD because H2 suppresses the formation of excess amount of C2H2; however, H2 does not eliminate amorphous carbon even at H2/C2H2 ratios of 300. PECVD using a binary mixture of C2H2 and isotope-modified 13CH4 demonstrated that CH4 does not contribute to CNT growth in C2H2-assisted thermal CVD. Atmospheric-pressure PECVD performed with a He/CH4/H2 system is equivalent to C2H2-assisted thermal CVD without an etching gas. APRFD appears to produce a hidden species, which influences the CNT growth process.

  5. Atmospheric pressure plasma assisted calcination of composite submicron fibers

    NASA Astrophysics Data System (ADS)

    Medvecká, Veronika; Kováčik, Dušan; Tučeková, Zlata; Zahoranová, Anna; Černák, Mirko

    2016-08-01

    The plasma assisted calcination of composite organic/inorganic submicron fibers for the preparation of inorganic fibers in submicron scale was studied. Aluminium butoxide/polyvinylpyrrolidone fibers prepared by electrospinning were treated using low-temperature plasma generated by special type of dielectric barrier discharge, so called diffuse coplanar surface barrier discharge (DCSBD) at atmospheric pressure in ambient air, synthetic air, oxygen and nitrogen. Effect of plasma treatment on base polymer removal was investigated by using Attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy. Influence of working gas on the base polymer reduction was studied by energy-dispersive X-ray spectroscopy (EDX) and CHNS elemental analysis. Changes in fibers morphology were observed by scanning electron microscopy (SEM). High efficiency of organic template removal without any degradation of fibers was observed after plasma treatment in ambient air. Due to the low-temperature approach and short exposure time, the plasma assisted calcination is a promising alternative to the conventional thermal calcination. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  6. Study of organic pollutants oxidation by atmospheric plasma discharge

    NASA Astrophysics Data System (ADS)

    Gumuchian, Diane; Cavadias, Simeon; Duten, Xavier; Tatoulian, Michael; da Costa, Patrick; Ognier, Stephanie

    2013-09-01

    Ozonation is one of the usual steps in water treatment processes. However, some organic molecules (acetic acid) cannot be decomposed during ozonation. In that context, we are developing an Advanced Oxidation Process based on the use of a needle plate discharge at atmospheric pressure. The process is a reactor with a plasma discharge between a high voltage electrode and the solution in controlled atmosphere. Characterizations of the plasma obtained in different atmospheres were carried out (Optical Emission Spectroscopy, iCCD camera observations, etc). The efficiency of the process was evaluated by the percentage of degradation of the model-pollutant, measured by liquid chromatography analysis. Treatments in nitrogen lead to the formation of NOx species that decrease the efficiency of the process. Indeed, NOx lead to the consumption of actives species created. Treatments in argon are the most efficient. Two hypotheses are considered: (i) metastable argon participates to the degradation of acetic acid or to the formation of radicals (ii) discharges in argon lead to the formation of many streamers of low energy that increase the interface plasma/solution.

  7. 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.

  8. Surface wave propagation characteristics in atmospheric pressure plasma column

    NASA Astrophysics Data System (ADS)

    Pencheva, M.; Benova, E.; Zhelyazkov, I.

    2007-04-01

    In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency (ν/ω) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption ν/ω = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary ν/ω. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance.

  9. 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.

  10. The interaction of the atmosphere of Enceladus with Saturn's plasma.

    PubMed

    Tokar, R L; Johnson, R E; Hill, T W; Pontius, D H; Kurth, W S; Crary, F J; Young, D T; Thomsen, M F; Reisenfeld, D B; Coates, A J; Lewis, G R; Sittler, E C; Gurnett, D A

    2006-03-10

    During the 14 July 2005 encounter of Cassini with Enceladus, the Cassini Plasma Spectrometer measured strong deflections in the corotating ion flow, commencing at least 27 Enceladus radii (27 x 252.1 kilometers) from Enceladus. The Cassini Radio and Plasma Wave Science instrument inferred little plasma density increase near Enceladus. These data are consistent with ion formation via charge exchange and pickup by Saturn's magnetic field. The charge exchange occurs between neutrals in the Enceladus atmosphere and corotating ions in Saturn's inner magnetosphere. Pickup ions are observed near Enceladus, and a total mass loading rate of about 100 kilograms per second (3 x 10(27) H(2)O molecules per second) is inferred. PMID:16527967

  11. Temporal modulation of plasma species in atmospheric dielectric barrier discharges

    SciTech Connect

    Yang, Aijun; Wang, Xiaohua E-mail: mzrong@mail.xjtu.edu.cn; Liu, Dingxin; Rong, Mingzhe E-mail: mzrong@mail.xjtu.edu.cn; Kong, Michael G.

    2014-07-15

    The atmospheric pressure dielectric barrier discharge in helium is a pulsed discharge in nature and the moment of maximum species densities is almost consistent with peak discharge current density. In this paper, a one-dimensional fluid model is used to investigate the temporal structure of plasma species in an atmospheric He-N{sub 2} dielectric barrier discharge (DBD). It is demonstrated that there exist microsecond delays of the moments of the maximum electron and ion densities from the peak of discharge current density. These time delays are caused by a competition between the electron impact and Penning ionizations, modulated by the N{sub 2} level in the plasma-forming gas. Besides, significant electron wall losses lead to the DBD being more positively charged and, with a distinct temporal separation in the peak electron and cation densities, the plasma is characterized with repetitive bursts of net positive charges. The temporal details of ionic and reactive plasma species may provide a new idea for some biological processes.

  12. Plasma Ion Sources for Atmospheric Pressure Ionization Mass Spectrometry.

    NASA Astrophysics Data System (ADS)

    Zhao, Jian-Guo

    1994-01-01

    Atmospheric pressure ionization (API) sources using direct-current (DC) and radio-frequency (RF) plasma have been developed in this thesis work. These ion sources can provide stable discharge currents of ~ 1 mA, 2-3 orders of magnitude larger than that of the corona discharge, a widely used API source. The plasmas can be generated and maintained in 1 atm of various buffer gases by applying -500 to -1000 V (DC plasma) or 1-15 W with a frequency of 165 kHz (RF plasma) on the needle electrode. These ion sources have been used with liquid injection to detect various organic compounds of pharmaceutical, biotechnological and environmental interest. Key features of these ion sources include soft ionization with the protonated molecule as the largest peak, and superb sensitivity with detection limits in the low picogram or femtomole range and a linear dynamic range over ~4 orders of magnitude. The RF plasma has advantages over the DC plasma in its ability to operate in various buffer gases and to produce a more stable plasma. Factors influencing the performance of the ion sources have been studied, including RF power level, liquid flow rate, chamber temperature, solvent composition, and voltage affecting the collision induced dissociation (CID). Ionization of hydrocarbons by the RF plasma API source was also studied. Soft ionization is generally produced. To obtain high sensitivity, the ion source must be very dry and the needle-to-orifice distance must be small. Nitric oxide was used to enhance the sensitivity. The RF plasma source was then used for the analysis of hydrocarbons in auto emissions. Comparisons between the corona discharge and the RF plasma have been made in terms of discharge current, ion residence time, and the ion source model. The RF plasma source provides larger linear dynamic range and higher sensitivity than the corona discharge, due to its much larger discharge current. The RF plasma was also observed to provide longer ion residence times and was not

  13. Io's neutral clouds: From the atmosphere to the plasma torus

    NASA Astrophysics Data System (ADS)

    Burger, Matthew Howard

    2003-10-01

    Since the discovery of sodium thirty years ago, observations of Io's neutral features have provided essential insight into understanding the relationship between the Io's atmosphere and the Io torus, a ring of plasma encircling Jupiter. In this thesis I use observations and models of lo's corona, extended neutral clouds, and fast sodium jet to probe the interactions between the atmosphere, torus, and neutral clouds. A corona and neutral cloud model, based on the model of Wilson and Schneider (1999), has been developed to study neutral loss from Io. Neutrals are ejected from Io's exobase and their trajectories followed under the influence of gravity until lost into the plasma torus. I also developed description of the plasma torus based on Voyager and ground-based observations to accurately determine neutral lifetimes. Mutual eclipsing events between Galilean satellites were used to measure the shape of lo's sodium corona, revealing a corona that is only approximately spherically symmetric around Io. I discovered a previously undetected asymmetry: the sub-Jupiter corona is denser than the anti-Jupiter corona. Modeling implies that sodium source from the sub-Jupiter hemisphere must be twice as large as from the anti-Jupiter hemisphere. The Galileo spacecraft has imaged a remarkable atmospheric escape process occurring in Io's ionosphere. Electrodynamic consequences of Io's motion through Jupiter's magnetosphere drive mega-amp currents through lo's ionosphere; some sodium ions carrying this current are neutralized as they leave the atmosphere. The Galileo images show that the resulting fast sodium jet removes ˜5 × 1025 atoms sec-1 from Io's atmosphere. The source region of the jet is much smaller than Io itself implying that the ionosphere is densest near Io's equator. A model-based comparison of the neutral oxygen and sodium clouds details differences in the morphologies and spatial extent of each: sodium extends only 1/4 the way around Jupiter while oxygen forms a

  14. An optical fiber sensing technique for temperature distribution measurements in microwave heating

    NASA Astrophysics Data System (ADS)

    Wada, Daichi; Sugiyama, Jun-ichi; Zushi, Hiroaki; Murayama, Hideaki

    2015-08-01

    We introduce an optical fiber sensing technique that can measure the temperature distributions along a fiber during microwave heating. We used a long-length fiber Bragg grating (FBG) as an electromagnetic-immune sensor and interrogated temperature distributions along the FBG by an optical frequency domain reflectometry. Water in a glass tube with a length of 820 mm was heated in a microwave oven, and its temperature distribution along the glass tube was measured using the sensing system. The temperature distribution was obtained in 5 mm intervals. Infrared radiometry was also used to compare the temperature measurement results. Time and spatial variations of the temperature distribution profiles were monitored for several microwave input powers. The results clearly depict inhomogeneous temperature profiles. The applicability and effectiveness of the optical fiber distributed measurement technique in microwave heating are demonstrated.

  15. The utilization of microwave heating for the fabrication of sintered reaction-bonded silicon nitride

    SciTech Connect

    Kiggans, J.O.; Tiegs, T.N.; Lin, H.T.; Holcombe, C.E.

    1995-12-31

    The results of studies in which microwave heating was used to fabricate sintered reaction-bonded silicon nitride (SRBSN) are reviewed. These results are compared to parallel studies where conventional heating was used for the fabrication of these materials. Microwave fabrication of SRBSN involves a single heating cycle, whereas conventional processing requires two separate furnace runs and sample packaging steps. SRBSN containing high levels of sintering aids which were fabricated by microwave heating showed improved strength and toughness, as compared to those materials fabricated using a conventional resistance-heated furnace. An analysis of the microstructures of the microwave fabricated materials showed enhanced acicular grain growth as compared to conventionally heated material. Results are presented on studies involving the scale-up of the microwave fabrication process.

  16. Plasma Processing with a One Atmosphere Uniform Glow Discharge Plasma (OAUGDP)

    NASA Astrophysics Data System (ADS)

    Reece Roth, J.

    2000-10-01

    The vast majority of all industrial plasma processing is conducted with glow discharges at pressures below 10 torr. This has limited applications to high value workpieces as a result of the large capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharges would play a much larger industrial role if they could be operated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) has been developed at the University of Tennessee Plasma Sciences Laboratory. The OAUGDP is non-thermal RF plasma with the time-resolved characteristics of a classical low pressure DC normal glow discharge. An interdisciplinary team was formed to conduct exploratory investigations of the physics and applications of the OAUGDP. This team includes collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC) and the Departments of Electrical and Computer Engineering, Microbiology, Food Science and Technology, and Mechanical and Aerospace Engineering and Engineering Science. Exploratory tests were conducted on a variety of potential plasma processing and other applications. These include the use of OAUGDP to sterilize medical and dental equipment and air filters; diesel soot removal; plasma aerodynamic effects; electrohydrodynamic (EDH) flow control of the neutral working gas; increasing the surface energy of materials; increasing the wettability and wickability of fabrics; and plasma deposition and directional etching. A general overview of these topics will be presented.

  17. Numerical Analysis of Heat Transfer Characteristics in Microwave Heating of Magnetic Dielectrics

    NASA Astrophysics Data System (ADS)

    Peng, Zhiwei; Hwang, Jiann-Yang; Park, Chong-Lyuck; Kim, Byoung-Gon; Onyedika, Gerald

    2012-03-01

    A numerical simulation of heat transfer during the microwave heating process of magnetite, which is a two-dimensional (2-D) magnetic dielectric, subjected to heat conduction, convection, and radiation was performed. The heat transfer process was modeled using an explicit finite-difference approach, and the temperature profiles for different heating parameters were generated through developing a code in Mathematica 7.0 (Wolfram Research, Inc., Champaign, IL). The temperature in the sample increases rapidly in 1 minute and nonuniform temperature distribution inside the object is observed. An obvious temperature hot spot is formed in the corner of the predicted temperature profile initially, which shifts to the center of the object as heating power increases. Microwave heating at 915 MHz exhibits better heating uniformity than 2450 MHz mainly because of the larger microwave penetration depth. It is also observed that the heating homogeneity in the object can be improved by reducing the dimension of object. The effects of heating time, microwave power, microwave frequency, and object dimension need to be considered to obtain high heating performance and avoid/minimize thermal runaway resulting from temperature nonuniformity in large-scale microwave heating.

  18. Surface modification of plasmonic nanostructured materials with thiolated oligonucleotides in 10 seconds using selective microwave heating.

    PubMed

    Abel, Biebele; Aslan, Kadir

    2012-11-01

    This study demonstrates the proof-of-principle of rapid surface modification of plasmonic nanostructured materials with oligonucleotides using low power microwave heating. Due to their interesting optical and electronic properties, silver nanoparticle films (SNFs, 2 nm thick) deposited onto glass slides were used as the model plasmonic nanostructured materials. Rapid surface modification of SNFs with oligonucleotides was carried out using two strategies (1) Strategy 1: for ss-oligonucleotides, surface hybridization and (2) Strategy 2: for ds-oligonucleotides, solution hybridization), where the samples were exposed to 10, 15, 30 and 60 seconds microwave heating. To assess the efficacy of our new rapid surface modification technique, identical experiments carried out without the microwave heating (i.e., conventional method), which requires 24 hours for the completion of the identical steps. It was found that SNFs can be modified with ss- and ds-oligonucleotides in 10 seconds, which typically requires several hours of incubation time for the chemisorption of thiol groups on to the planar metal surface using conventional techniques. PMID:23645933

  19. Vesicouretal reflux in children: A phantom study of microwave heating and radiometric thermometry of pediatric bladder

    PubMed Central

    Birkelund, Yngve; Klemetsen, Øystein; Jacobsen, Svein K.; Arunachalam, Kavitha; Maccarini, Paolo; Stauffer, Paul R.

    2012-01-01

    We have investigated the use of microwave heating and radiometry to safely heat urine inside a pediatric bladder. The medical application for this research is to create a safe and reliable method to detect vesicoureteral reflux, a pediatric disorder, where urine flow is reversed and flows from the bladder back up into the kidney. Using fat and muscle tissue models, we have performed both experimental and numerical simulations of a pediatric bladder model using planar dual concentric conductor microstrip antennas at 915 MHz for microwave heating. A planar elliptical antenna connected to a 500 MHz bandwidth microwave radiometer centered at 3.5 GHz was used for non-invasive temperature measurement inside tissue. Temperatures were measured in the phantom models at points during the experiment with implanted fiberoptic sensors, and 2D distributions in cut planes at depth in the phantom with an infrared camera at the end of the experiment. Cycling between 20 second with 20 Watts power for heating, and 10 seconds without power to allow for undisturbed microwave radiometry measurements, the experimental results show that the target tissue temperature inside the phantom increases fast and that the radiometer provides useful measurements of spatially averaged temperature of the illuminated volume. The presented numerical and experimental results show excellent concordance, which confirms that the proposed system for microwave heating and radiometry is applicable for safe and reliable heating of pediatric bladder. PMID:21900069

  20. Nucleation and crystallization of tailing-based glass-ceramics by microwave heating

    NASA Astrophysics Data System (ADS)

    Li, Bao-wei; Li, Hong-xia; Zhang, Xue-feng; Jia, Xiao-lin; Sun, Zhi-chao

    2015-12-01

    The effect of microwave radiation on the nucleation and crystallization of tailing-based glass-ceramics was investigated using a 2.45 GHz multimode microwave cavity. Tailing-based glass samples were prepared from Shandong gold tailings and Guyang iron tailings utilizing a conventional glass melting technique. For comparison, the tailing-based glass samples were crystallized using two different heat-treatment methods: conventional heating and hybrid microwave heating. The nucleation and crystallization temperatures were determined by performing a differential thermal analysis of the quenched tailing-based glass. The prepared glass-ceramic samples were further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermal expansion coefficient measurements, and scanning electron microscopy. The results demonstrated that hybrid microwave heating could be successfully used to crystallize the tailing-based glass, reduce the processing time, and decrease the crystallization temperature. Furthermore, the results indicated that the nucleation and crystallization mechanism of the hybrid microwave heating process slightly differs from that of the conventional heating process.

  1. Vesicoureteral reflux in children: a phantom study of microwave heating and radiometric thermometry of pediatric bladder.

    PubMed

    Birkelund, Yngve; Klemetsen, Øystein; Jacobsen, Svein K; Arunachalam, Kavitha; Maccarini, Paolo; Stauffer, Paul R

    2011-11-01

    We have investigated the use of microwave heating and radiometry to safely heat urine inside a pediatric bladder. The medical application for this research is to create a safe and reliable method to detect vesicoureteral reflux, a pediatric disorder, where urine flow is reversed and flows from the bladder back up into the kidney. Using fat and muscle tissue models, we have performed both experimental and numerical simulations of a pediatric bladder model using planar dual concentric conductor microstrip antennas at 915 MHz for microwave heating. A planar elliptical antenna connected to a 500 MHz bandwidth microwave radiometer centered at 3.5 GHz was used for noninvasive temperature measurement inside tissue. Temperatures were measured in the phantom models at points during the experiment with implanted fiberoptic sensors, and 2-D distributions in cut planes at depth in the phantom with an infrared camera at the end of the experiment. Cycling between 20 s with 20 Watts power for heating, and 10 s without power to allow for undisturbed microwave radiometry measurements, the experimental results show that the target tissue temperature inside the phantom increases fast and that the radiometer provides useful measurements of spatially averaged temperature of the illuminated volume. The presented numerical and experimental results show excellent concordance, which confirms that the proposed system for microwave heating and radiometry is applicable for safe and reliable heating of pediatric bladder. PMID:21900069

  2. Sterilization of Surfaces with a Handheld Atmospheric Pressure Plasma

    NASA Astrophysics Data System (ADS)

    Hicks, Robert; Habib, Sara; Chan, Wai; Gonzalez, Eleazar; Tijerina, A.; Sloan, Mark

    2009-10-01

    Low temperature, atmospheric pressure plasmas have shown great promise for decontaminating the surfaces of materials and equipment. In this study, an atmospheric pressure, oxygen and argon plasma was investigated for the destruction of viruses, bacteria, and spores. The plasma was operated at an argon flow rate of 30 L/min, an oxygen flow rate of 20 mL/min, a power density of 101.0 W/cm^3 (beam area = 5.1 cm^2), and at a distance from the surface of 7.1 mm. An average 6log10 reduction of viable spores was obtained after only 45 seconds of exposure to the reactive gas. By contrast, it takes more than 35 minutes at 121^oC to sterilize anthrax in an autoclave. The plasma properties were investigated by numerical modeling and chemical titration with nitric oxide. The numerical model included a detailed reaction mechanism for the discharge as well as for the afterglow. It was predicted that at a delivered power density of 29.3 W/cm^3, 30 L/min argon, and 0.01 volume% O2, the plasma generated 1.9 x 10^14 cm-3 O atoms, 1.6 x 10^12 cm-3 ozone, 9.3 x 10^13 cm-3 O2(^1δg), and 2.9 x 10^12 cm-3 O2(^1σ^+g) at 1 cm downstream of the source. The O atom density measured by chemical titration with NO was 6.0 x 10^14 cm-3 at the same conditions. It is believe that the oxygen atoms and the O2(^1δg) metastables were responsible for killing the anthrax and other microorganisms.

  3. A global mechanism creating low atmospheric luminous cold plasmas

    NASA Astrophysics Data System (ADS)

    Gitle Hauge, Bjørn; Petter Strand, Erling

    2014-05-01

    Red, white/yellow and blue balls of light have been observed in the low atmosphere over the Hessdalen valley , Norway, standing still and moving horizontally with random speed. Characteristics of these transient luminous phenomena in Hessdalen, and data from America, suggest that the process which creates these low atmospheric plasmas is a global mechanism, not only localized to the remote and desolated Hessdalen valley in Norway (62Deg.N - 11Deg.E). Transient luminous phenomena's has been observed in the low atmosphere over the Hessdalen valley for over 200 years. The first written documentation goes back to 1811 when the priest Jakob Tode Krogh wrote about it in his diary. Since 1982, inhabitants, tourists, journalists and scientists have done recurrent observations. E.P.Strand conducted the first scientific campaign in 1984, documenting over 50 observations in one month. 15 years later, Norwegian and Italian scientists installed the first permanent automated research base here. In 2010 French researchers joined this collaboration and installed two additional research bases. This transient luminous phenomenon, TLP, has been detected simultaneously on optical and radar devices, but electromagnetic radiation from this phenomenon has until now eluded detection. Smirnov (1994) and Zou(1994) was among the first scientist who used plasma physics trying to explain this phenomenon. Work done by Pavia & Taft (2010 and 2012) suggests that the TLP in Hessdalen probably is dusty or cold plasma, arranged as a cluster of Coulomb crystals. Optical spectrum data obtained by Strand (1984), Teodorani (2004) and Hauge (2007) showing a continuous optical spectrum support this hypothesis. Pictures of spiraling light rays obtained by Strand in 1984, and Hauge in 2004 and 2010 suggests that this plasma is moving in a strong magnetic field, and might be created by it. Radar reflections from the TLP in Hessdalen obtained by Strand in 1984 and Montebugnoli and Monari in 2007 points

  4. Surface Modification by Atmospheric Pressure Plasma for Improved Bonding

    NASA Astrophysics Data System (ADS)

    Williams, Thomas Scott

    An atmospheric pressure plasma source operating at temperatures below 150?C and fed with 1.0-3.0 volume% oxygen in helium was used to activate the surfaces of the native oxide on silicon, carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024. Helium and oxygen were passed through the plasma source, whereby ionization occurred and ˜10 16 cm-3 oxygen atoms, ˜1015 cm -3 ozone molecules and ˜1016 cm-3 metastable oxygen molecules (O21Deltag) were generated. The plasma afterglow was directed onto the substrate material located 4 mm downstream. Surface properties of the plasma treated materials have been investigated using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and x-ray photoelectron spectroscopy (XPS). The work presented herein establishes atmospheric-pressure plasma as a surface preparation technique that is well suited for surface activation and enhanced adhesive bond strength in a variety of materials. Atmospheric plasma activation presents an environmentally friendly alternative to wet chemical and abrasive methods of surface preparation. Attenuated total internal reflection infrared spectroscopy was used to study the aging mechanism of the native oxide on silicon. During storage at ambient conditions, the water contact angle of a clean surface increased from <5° to 40° over a period of 12 hours. When stored under a nitrogen purge, the water contact angle of a clean surface increased from <5° to 30° over a period of 40-60 hours. The change in contact angle resulted from the adsorption of nonanal onto the exposed surface hydroxyl groups. The rate of adsorption of nonanal under a nitrogen purged atmosphere ranged from 0.378+/-0.011 hr-1 to 0.182+/-0.008 hr -1 molecules/(cm2•s), decreasing as the fraction of hydrogen-bonded hydroxyl groups increased from 49% to 96% on the SiO 2 surface. The adsorption of the organic contaminant could be suppressed indefinitely by storing the

  5. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    SciTech Connect

    Robert F. Hicks; Hans W. Herrmann

    2003-12-15

    The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioactive metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. The technology shows a great potential for accelerating the clean-up effort for the equipment and structures contaminated with radioactive materials within the DOE complex. The viability of this technology has been demonstrated by selectively and rapidly stripping uranium from stainless steel surfaces at low temperature. Studies on uranium oxide have shown that etch rates of 4.0 microns per minute can be achieved at temperature below 473 K. Over the past three years, we have made numerous improvements in the design of the atmospheric pressure plasma source. We are now able to scale up the plasma source to treat large surface areas.

  6. Atmospheric-pressure plasma decontamination/sterilization chamber

    DOEpatents

    Herrmann, Hans W.; Selwyn, Gary S.

    2001-01-01

    An atmospheric-pressure plasma decontamination/sterilization chamber is described. The apparatus is useful for decontaminating sensitive equipment and materials, such as electronics, optics and national treasures, which have been contaminated with chemical and/or biological warfare agents, such as anthrax, mustard blistering agent, VX nerve gas, and the like. There is currently no acceptable procedure for decontaminating such equipment. The apparatus may also be used for sterilization in the medical and food industries. Items to be decontaminated or sterilized are supported inside the chamber. Reactive gases containing atomic and metastable oxygen species are generated by an atmospheric-pressure plasma discharge in a He/O.sub.2 mixture and directed into the region of these items resulting in chemical reaction between the reactive species and organic substances. This reaction typically kills and/or neutralizes the contamination without damaging most equipment and materials. The plasma gases are recirculated through a closed-loop system to minimize the loss of helium and the possibility of escape of aerosolized harmful substances.

  7. 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).

  8. Surface Modification by Atmospheric Pressure Plasma for Improved Bonding

    NASA Astrophysics Data System (ADS)

    Williams, Thomas Scott

    An atmospheric pressure plasma source operating at temperatures below 150?C and fed with 1.0-3.0 volume% oxygen in helium was used to activate the surfaces of the native oxide on silicon, carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024. Helium and oxygen were passed through the plasma source, whereby ionization occurred and ˜10 16 cm-3 oxygen atoms, ˜1015 cm -3 ozone molecules and ˜1016 cm-3 metastable oxygen molecules (O21Deltag) were generated. The plasma afterglow was directed onto the substrate material located 4 mm downstream. Surface properties of the plasma treated materials have been investigated using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and x-ray photoelectron spectroscopy (XPS). The work presented herein establishes atmospheric-pressure plasma as a surface preparation technique that is well suited for surface activation and enhanced adhesive bond strength in a variety of materials. Atmospheric plasma activation presents an environmentally friendly alternative to wet chemical and abrasive methods of surface preparation. Attenuated total internal reflection infrared spectroscopy was used to study the aging mechanism of the native oxide on silicon. During storage at ambient conditions, the water contact angle of a clean surface increased from <5° to 40° over a period of 12 hours. When stored under a nitrogen purge, the water contact angle of a clean surface increased from <5° to 30° over a period of 40-60 hours. The change in contact angle resulted from the adsorption of nonanal onto the exposed surface hydroxyl groups. The rate of adsorption of nonanal under a nitrogen purged atmosphere ranged from 0.378+/-0.011 hr-1 to 0.182+/-0.008 hr -1 molecules/(cm2•s), decreasing as the fraction of hydrogen-bonded hydroxyl groups increased from 49% to 96% on the SiO 2 surface. The adsorption of the organic contaminant could be suppressed indefinitely by storing the

  9. Solution-processed flexible ZnO transparent thin-film transistors with a polymer gate dielectric fabricated by microwave heating

    NASA Astrophysics Data System (ADS)

    Yang, Chanwoo; Hong, Kipyo; Jang, Jaeyoung; Chung, Dae Sung; An, Tae Kyu; Choi, Woon-Seop; Eon Park, Chan

    2009-11-01

    We report the development of solution-processed zinc oxide (ZnO) transparent thin-film transistors (TFTs) with a poly(2-hydroxyethyl methacrylate) (PHEMA) gate dielectric on a plastic substrate. The ZnO nanorod film active layer, prepared by microwave heating, showed a highly uniform and densely packed array of large crystal size (58 nm) in the [002] direction of ZnO nanorods on the plasma-treated PHEMA. The flexible ZnO TFTs with the plasma-treated PHEMA gate dielectric exhibited an electron mobility of 1.1 cm2 V-1 s-1, which was higher by a factor of ~8.5 than that of ZnO TFTs based on the bare PHEMA gate dielectric.

  10. Voltage distribution over capacitively coupled plasma electrode for atmospheric-pressure plasma generation

    PubMed Central

    2013-01-01

    When capacitively coupled plasma (CCP) is used to generate large-area plasma, the standing wave effect becomes significant, which results in the hindering of the uniform plasma process such as in a plasma etcher or plasma chemical vapor deposition. In this study, the transmission line modeling method is applied to calculate the voltage distribution over atmospheric-pressure CCP electrodes with the size of 1 m × 0.2 m. The measured plasma impedance in our previous study was used in the present calculation. The results of the calculations clearly showed the effects of excitation frequency and the impedance of the plasma on the form of the voltage distribution caused by the standing wave effect. In the case of 150 MHz frequency, the standing wave effect causes a drastic change in the voltage distribution via plasma ignition; however, the change is small for 13.56 MHz. It was also clarified that the power application position is important for obtaining a uniform voltage distribution. PMID:23634893

  11. Tailoring non-equilibrium atmospheric pressure plasmas for healthcare technologies

    NASA Astrophysics Data System (ADS)

    Gans, Timo

    2012-10-01

    Non-equilibrium plasmas operated at ambient atmospheric pressure are very efficient sources for energy transport through reactive neutral particles (radicals and metastables), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. This includes the unique opportunity to deliver short-lived highly reactive species such as atomic oxygen and atomic nitrogen. Reactive oxygen and nitrogen species can initiate a wide range of reactions in biochemical systems, both therapeutic and toxic. The toxicological implications are not clear, e.g. potential risks through DNA damage. It is anticipated that interactions with biological systems will be governed through synergies between two or more species. Suitable optimized plasma sources are improbable through empirical investigations. Quantifying the power dissipation and energy transport mechanisms through the different interfaces from the plasma regime to ambient air, towards the liquid interface and associated impact on the biological system through a new regime of liquid chemistry initiated by the synergy of delivering multiple energy carrying species, is crucial. The major challenge to overcome the obstacles of quantifying energy transport and controlling power dissipation has been the severe lack of suitable plasma sources and diagnostic techniques. Diagnostics and simulations of this plasma regime are very challenging; the highly pronounced collision dominated plasma dynamics at very small dimensions requires extraordinary high resolution - simultaneously in space (microns) and time (picoseconds). Numerical simulations are equally challenging due to the inherent multi-scale character with very rapid electron collisions on the one extreme and the transport of chemically stable species characterizing completely different domains. This presentation will discuss our recent progress actively combining both advance optical diagnostics and multi-scale computer simulations.

  12. Tantalum Etching with an Atmospheric Pressure Plasma Jet

    NASA Astrophysics Data System (ADS)

    Teslow, Hilary; Herrmann, Hans; Rosocha, Louis

    2002-10-01

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

  13. Microwave capillary plasmas in helium at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Santos, M.; Noël, C.; Belmonte, T.; Alves, L. L.

    2014-07-01

    This work uses both simulations and experiments to study helium plasmas (99.999% purity), sustained by surface-wave discharges (2.45 GHz frequency) in capillary tubes (3 mm in-radius) at atmospheric pressure. The simulations use a self-consistent homogeneous and stationary collisional-radiative model (CRM) that solves the rate balance equations for the different species present in the plasma (electrons, He+ and He_2^+ ions, He(n ⩽ 6) excited states and He_2^* excimers) and the gas thermal balance equation, coupled with the two-term electron Boltzmann equation (including direct and stepwise inelastic and superelastic collisions as well as electron-electron collisions). The experiments use optical emission spectroscopy diagnostics to measure the electron density ne (from the Hβ Stark broadening), the gas temperature Tg (from the ro-vibrational transitions of OH, present at trace concentrations) and the populations of excited states in the energy region 22.7-24.2 eV, whose spectrum allows determining the excitation temperature Texc. Measurements yield ne ≃ (2.45 ± 1.4) × 1013 cm-3, Tg ≃ 1700 ± 100 K and Texc ≃ 2793 ± 116 K, for a ˜180 ± 10 W power coupled and ˜1 cm length plasma column. The model predictions at ne = 1.7 × 1013 cm-3 are in very good agreement with measurements yielding Tg = 1800 K, Texc = 2792 K (for ˜30% average relative error between calculated and measured excited-state densities), and a power absorbed by the plasma per unit length of 165 W cm-1. The model results depend strongly on ne, and hence on the plasma conductivity and on the power coupled to the plasma. The coupling of a thermal module to the CRM has been shown to be crucial. Increasing the electron density leads to very high gas temperature values, which limits the variation range of (ne, Tg) as input parameters to the model.

  14. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    SciTech Connect

    Robert F. Hicks; Gary S. Selwyn

    2001-01-09

    Project was to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. With the invention of the atmospheric-pressure plasma jet the goal was achieved. This device selectively etches heavy metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. Studies on tantalum, a surrogate material for plutonium, have shown that etch rate of 6.0 microns per minute can be achieved under mild conditions. Over the past three years, we have made numerous improvements in the design of the plasma jet. It may now be operated for hundreds of hours and not undergo any degradation in performance. Furthermore, small compact units have been developed, which are easily deployed in the field.

  15. Plasma Flow Past Cometary and Planetary Satellite Atmospheres

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.; Gombosi, Tamas I.; Kabin, Konstantin

    2000-01-01

    The tenuous atmospheres and ionospheres of comets and outer planet satellites share many common properties and features. Such similarities include a strong interaction with their outer radiation, fields and particles environs. For comets the interaction is with the magnetized solar wind plasma, whereas for satellites the interaction is with the strongly magnetized and corotating planetary magnetospheric plasma. For this reason there are many common or analogous physical regimes, and many of the same modeling techniques are used to interpret remote sensing and in situ measurements in order to study the important underlying physical phenomena responsible for their appearances. We present here a review of various modeling approaches which are used to elucidate the basic properties and processes shaping the energetics and dynamics of these systems which are similar in many respects.

  16. Apoptosis in vascular cells induced by cold atmospheric plasma treatment

    NASA Astrophysics Data System (ADS)

    Sladek, Raymond; Stoffels, Eva

    2006-10-01

    Apoptosis is a natural mechanism of cellular self-destruction. It can be triggered by moderate, yet irreversible damage. Apoptosis plays a major role in tissue renewal. Artificial apoptosis induction will become a novel therapy that meets all requirements for tissue-saving surgery. Diseased tissues can disappear without inflammation and scarring. This is particularly important in treatment of blockages in body tracts (e.g. cardiovascular diseases). Artificial induction of apoptosis can be achieved by means of cold plasma treatment. In this work an atmospheric micro-plasma operated in helium/air has been used to induce apoptosis in vascular cells. Parametric studies of apoptosis induction have been conducted; the efficiency is almost 100%. The apoptotic factors are ROS/RNS (reactive oxygen and nitrogen species). Their densities in the plasma have been measured by mass spectrometry. For apoptosis induction, RNS seem to be more important than ROS, because of their relative abundance. Moreover, addition of a ROS scavenger (ascorbic acid) to the cell culture medium does not reduce the occurrence of apoptosis. Cold plasma is a very efficient tool for fundamental studies of apoptosis, and later, for controlled tissue removal in vivo.

  17. 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.

  18. Characteristics of dielectric barrier discharge plasmas in atmospheric humid air

    NASA Astrophysics Data System (ADS)

    Fukuda, Y.; Fukui, K.; Iwami, R.; Matsuoka, Y.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    Atmospheric pressure plasmas have a great advantage for industrial applications such as surface modifications, sterilization and film preparation. In particular, reactive plasmas including OH radicals can be generated in humid air. On the other hand, it is known that dielectric barrier discharge (DBD) plasmas in air are strongly affected by humidity. In this study, a twisted pair sample is used as a DBD electrode. The twisted pair consists of two enameled wires, and it is installed in a climate chamber to control ambient temperature and humidity. Repetitive impulse voltage pulses were applied to the twisted pair to produce DBD plasmas. Light emission, electromagnetic wave and current pulses were used to detect discharge activities. The discharge inception voltage (DIV) is basically determined by Paschen curve in air, however, the DIV was decreased by increasing the humidity. In addition, it was found that there were largely scattered data of DIV at the low humidity condition. After the pre-discharges, the DIV reached to the steady state value. On the other hand, there was no scattering of the observed DIV at the high humidity condition. Measurements of surface potential of the sample after the discharge show these behaviors could be explained by surface charge accumulation on the enameled wire. It is noted that there was no fluctuation in the DIV data in the case of unipolar voltage pulse.

  19. Generation and characterization of atmospheric plasma torch array

    SciTech Connect

    Koretzky, E.; Kuo, S.P.

    1997-12-31

    Using a capacitively coupled electrical discharge, an array of plasma torches can be produced simultaneously by using a common 60 cycle power source (i.e. a simple wall plug) at atmospheric pressure. The size of each torch depends on the geometry of the electrode pair and the streaming speed of the air flow. Such a flat panel plasma torch array can be made into the desired volume and plasma density. A laser beam is used to measure the dimensions of the torch. It is found that each torch has a radius of about 1 cm and a height of about 6.5 cm. Surprisingly, it is shown that the torch can cause up to 80% modulation of the laser beam intensity. From the voltage and current measurements, the average power consumption of each torch is estimated to be 0.6 kW. The electron density can also be estimated and is found to exceed 10{sup 13}cm{sup {minus}3}. The discharge may be represented by a lump circuit. Thus, a computer simulation of the discharge is performed. The results are found to be in good agreement with experimental measurements. Simulations have also been performed to study the dependence of average electron density, with the electron-ion recombination coefficient as a parameter. The study is aimed at developing an efficient large volume dense plasma for industrial applications.

  20. Atmospheric pressure plasma enhanced spatial ALD of silver

    SciTech Connect

    Bruele, Fieke J. van den Smets, Mireille; Illiberi, Andrea; Poodt, Paul; Buskens, Pascal; Roozeboom, Fred

    2015-01-15

    The authors have investigated the growth of thin silver films using a unique combination of atmospheric process elements: spatial atomic layer deposition and an atmospheric pressure surface dielectric barrier discharge plasma source. Silver films were grown on top of Si substrates with good purity as revealed by resistivity values as low as 18 μΩ cm and C- and F-levels below detection limits of energy dispersive x-ray analysis. The growth of the silver films starts through the nucleation of islands that subsequently coalesce. The authors show that the surface island morphology is dependent on surface diffusion, which can be controlled by temperature within the deposition temperature range of 100–120 °C.

  1. 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.

  2. Effects of different additives with assistance of microwave heating for heavy metal stabilization in electronic industry sludge.

    PubMed

    Jothiramalingam, R; Lo, Shang-Lien; Chen, Ching-lung

    2010-01-01

    Electronic industrial wastewater sludge in Taiwan is normally passed through an acid-extraction process to reclaim most of the copper ions, the remaining residue may still need to be treated by various stabilization technologies using suitable additives. Cement solidification is used as the common method to stabilize the industrial wastewater sludge in Taiwan. However, this method has the disadvantage of an increase in waste volume. In the present study selective additives such as sodium sulfide, barium manganate and different phase of alumina were tested as a possible alternate additive to stabilize the heavy metal ion in the treated solid waste sludge via microwave heating treatment. The effects of additive amount, power of microwave irradiation and reaction time have been studied. Heavy metal leaching capacity is determined by using standard toxicity characteristic leaching procedure test and elemental content in the leachate is analyzed by inductively coupled plasma analysis. Sodium sulfide is effectively stabilizing the leaching copper ion with high selectivity in the presence of microwave irradiation and finally stabilized in the form of copper sulfide, which is a significant reaction to stabilize the copper ion leaching in the waste sludge. Complete stabilization of heavy metal ion and copper ion content (<5mgL(-1)) in industrial sludge is achieved by heating the microwave treated barium manganate and alumina additives by adopting suitable reaction conditions. Hybrid microwave and conventional heating process with minor amount of additive providing the efficient heavy metal stabilization for treated electronic industry waste sludge. PMID:19945139

  3. Biomedical Applications of the Cold Atmospheric Plasma: Cell Responses

    NASA Astrophysics Data System (ADS)

    Volotskova, Olga

    Current breakthrough research on cold atmospheric plasma (CAP) demonstrates that CAP has great potential in various areas, including medicine and biology, thus providing a new tool for living tissue treatment. Depending on the configuration the cold plasma sources can be used in the following areas: wound healing, skin diseases, hospital hygiene, sterilization, antifungal treatments, dental care, cosmetics targeted cell/tissue removal, and cancer treatments. This dissertation is focused on the studies of biomedical applications of cold atmospheric plasma jet based on helium flow and resultant cell responses to the cold plasma treatment. The studies were carried out on extra-cellular and intra-cellular levels in vitro. The main practical applications are wound healing and alternative to existing cancer therapy methods, areas of great interest and significant challenges. The CAP jet was built in the Micropropulsion and Nanotechnology Laboratory of Dr. Michael Keidar, as a part of multidisciplinary collaboration with the GW Medical School (Dr. M.A. Stepp) concerned with plasma medicine and bioengineering studies. Normal and cancer cells have two fundamental behavioral properties, proliferation and motility, which can be evaluated through cell migration rates and cell cycle progression. Various microscopic, spectroscopic and flow cytometry techniques were used to characterize cell responses to the cold plasma treatment. It was found that CAP effect on the cells is localized within the area of the treatment (of around ˜ 5mm in diameter). The migration rates of the normal skin cells can be reduced up to ˜ 40%. However, depending on the cell type the required treatment time is different, thus differential treatment of various cells presented in tissue is possible. The CAP effect on the migration was explained through the changes of the cell surface proteins/integrins. It was also found that normal and cancer cells respond differently to the CAP treatment under the same

  4. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiromasa; Mizuno, Masaaki; Toyokuni, Shinya; Maruyama, Shoichi; Kodera, Yasuhiro; Terasaki, Hiroko; Adachi, Tetsuo; Kato, Masashi; Kikkawa, Fumitaka; Hori, Masaru

    2015-12-01

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  5. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    SciTech Connect

    Tanaka, Hiromasa; Mizuno, Masaaki; Toyokuni, Shinya; Maruyama, Shoichi; Kodera, Yasuhiro; Terasaki, Hiroko; Adachi, Tetsuo; Kato, Masashi; Kikkawa, Fumitaka; Hori, Masaru

    2015-12-15

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  6. Cold atmospheric plasma decontamination of the pericarps of fruit.

    PubMed

    Perni, Stefano; Liu, David W; Shama, Gilbert; Kong, Michael G

    2008-02-01

    This investigation describes the inactivation by cold atmospheric plasmas of one pathogenic and three spoilage organisms on the pericarps of mangoes and melons. The operating voltage necessary for efficient microbial decontamination of fruit pericarps was first established using Escherichia coli at a concentration of 10(7) CFU/cm2 on the surface of mango. It was found that, when the plasma was sustained slightly above its breakdown voltage of 12 kV (peak to peak), no inactivation was detected when cells were plated onto tryptone soya extract agar (TSA). However, when plated onto eosin methylene blue agar, sublethal injury corresponding to approximately 1 log reduction was achieved, whereas on TSA supplemented with 4% NaCl a greater reduction of 1.5 log was revealed. When the voltage was increased by 33% to 16 kV, a reduction in cell counts of 3 log was achieved on all three plating media. Further investigations at these new operating conditions were conducted using a range of spoilage microorganisms (Saccharomyces cerevisae, Pantoea agglomerans, and Gluconacetobacter liquefaciens) all at a surface concentration of 106 CFU/cm2 on the pericarps of mango and melon. P. agglomerans and G. liquefaciens were reduced below the detection limit (corresponding to 3 log) after only 2.5 s on both fruits, whereas E. coli required 5 s to reach the same level of inactivation. S. cerevisae was the most resistant organism studied and was reduced in numbers below the detection limit after 10 s on mango and 30 s on melon. The optical emission spectra generated by the cold atmospheric plasma at both high and low operating voltages were compared in order to identify putative lethal species. It was shown that an increase in the applied voltage led to more efficient production of reactive plasma species, particularly oxygen atoms, and the production of oxygen atoms was related to the level of bacterial inactivation achieved. Production of atomic oxygen could be used as an indicator of

  7. Atmospheric pressure plasmas: infection control and bacterial responses.

    PubMed

    Mai-Prochnow, Anne; Murphy, Anthony B; McLean, Keith M; Kong, Michael G; Ostrikov, Kostya Ken

    2014-06-01

    Cold atmospheric pressure plasma (APP) is a recent, cutting-edge antimicrobial treatment. It has the potential to be used as an alternative to traditional treatments such as antibiotics and as a promoter of wound healing, making it a promising tool in a range of biomedical applications with particular importance for combating infections. A number of studies show very promising results for APP-mediated killing of bacteria, including removal of biofilms of pathogenic bacteria such as Pseudomonas aeruginosa. However, the mode of action of APP and the resulting bacterial response are not fully understood. Use of a variety of different plasma-generating devices, different types of plasma gases and different treatment modes makes it challenging to show reproducibility and transferability of results. This review considers some important studies in which APP was used as an antibacterial agent, and specifically those that elucidate its mode of action, with the aim of identifying common bacterial responses to APP exposure. The review has a particular emphasis on mechanisms of interactions of bacterial biofilms with APP. PMID:24637224

  8. Atmospheric oxygen plasma activation of silicon (100) surfaces

    SciTech Connect

    Habib, Sara B.; Gonzalez, Eleazar II; Hicks, Robert F.

    2010-05-15

    Silicon (100) surfaces were converted to a hydrophilic state with a water contact angle of <5 deg. by treatment with a radio frequency, atmospheric pressure helium, and oxygen plasma. A 2 in. wide plasma beam, operating at 250 W, 1.0 l/min O{sub 2}, 30 l/min He, and a source-to-sample distance of 3{+-}0.1 mm, was scanned over the sample at 100{+-}2 mm/s. Plasma oxidation of HF-etched silicon caused the dispersive component of the surface energy to decrease from 55.1 to 25.8 dyn/cm, whereas the polar component of the surface energy increased from 0.3 to 42.1 dyn/cm. X-ray photoelectron spectroscopy revealed that the treatment generated a monolayer of covalently bonded oxygen on the Si(100) surface 0.15{+-}0.10 nm thick. The surface oxidation kinetics have been measured by monitoring the change in water contact angle with treatment time, and are consistent with a process that is limited by the mass transfer of ground-state oxygen atoms to the silicon surface.

  9. Killing Microorganisms with the One Atmosphere Uniform Glow Discharge Plasma

    NASA Astrophysics Data System (ADS)

    South, Suzanne; Kelly-Wintenberg, Kimberly; Montie, T. C.; Reece Roth, J.; Sherman, Daniel; Morrison, Jim; Chen, Zhiyu; Karakaya, Fuat

    2000-10-01

    There is an urgent need for the development of new technologies for sterilization and decontamination in the fields of healthcare and industrial and food processing that are safe, cost-effective, broad-spectrum, and not deleterious to samples. One technology that meets these criteria is the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). The OAUGDP operates in air and produces uniform plasma without filamentary discharges at room temperature, making this technology advantageous for sterilization of heat sensitive materials. The OAUGDP operates in a frequency band determined by the ion trapping mechanisms provided that, for air, the electric field is above 8.5kV/cm. The OAUGDP efficiently generates plasma reactive oxygen species (ROS) including atomic oxygen and oxygen free radicals without the requirement of a vacuum system. We have demonstrated the efficacy of the OAUGDP in killing microorganisms including bacteria, yeast, viruses, and spores in seconds to minutes on a variety of surfaces such as glass, films and fabrics, stainless steel, paper, and agar.

  10. Novel atmospheric plasma enhanced chitosan nanofiber/gauze composite wound dressings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electrospun chitosan nanofibers were deposited onto atmospheric plasma treated cotton gauze to create a novel composite bandage with higher adhesion, better handling properties, enhanced bioactivity, and moisture management. Plasma treatment of the gauze substrate was performed to improve the durabi...

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  12. Effects of cold atmospheric plasma on mucosal tissue culture

    NASA Astrophysics Data System (ADS)

    Welz, Christian; Becker, Sven; Li, Yang-Fang; Shimizu, Tetsuji; Jeon, Jin; Schwenk-Zieger, Sabina; Thomas, Hubertus M.; Isbary, Georg; Morfill, Gregor E.; Harréus, Ulrich; Zimmermann, Julia L.

    2013-01-01

    Thermal plasmas have been commonly used in medical applications such as plasma ablation and blood coagulation. Newer developments show that plasmas can be generated with ion temperatures close to room temperature: these non-thermal or so-called cold atmospheric plasmas (CAPs) therefore open up a wide range of further biomedical applications. Based on the understanding of the bactericidal, virucidal and fungicidal properties of CAPs, information about the effects of CAP on mucosal cells and tissue is still lacking. Therefore this study focuses on the interaction of CAP with healthy head and neck mucosal cells on a molecular level. To analyse this interaction in detail, fresh tissue samples from healthy nasal and pharyngeal mucosa were harvested during surgery, assembled to a three-dimensional tissue culture model (mini organ cultures) and treated with CAP for different treatment times. Effects on the viability, necrosis induction and mutagenic activity were evaluated with the trypan blue exclusion test, Annexin-V/PI staining and alkaline microgel electrophoresis (comet assay). Trypan blue exclusion test revealed that the CAP treatment significantly decreases the cell viability for all tested treatment times (5, 10, 30, 60 and 120 s p < 0.05), but only a treatment time of 120 s showed a cytotoxic effect as the viability dropped below 90%. Annexin-V/PI staining revealed a significant increase in necrosis in CAP treated pharyngeal tissue cultures for treatment times of 60 and 120 s (p < 0.05). For nasal tissue this effect was already detected for a 30 s treatment (p < 0.05). Comet assay analysis showed no mutagenic effects after exposure to CAP.

  13. 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.

  14. Atmospheric Pressure Non-Thermal Air Plasma Jet

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  15. Geometry for web microwave heating or drying to a desired profile in a waveguide

    DOEpatents

    Habeger, Jr., Charles C.; Patterson, Timothy F.; Ahrens, Frederick W.

    2005-11-15

    A microwave heater and/or dryer has a nonlinear or curvilinear relative slot profile geometry. In one embodiment, the microwave dryer has at least one adjustable field modifier making it possible to change the geometry of the heater or dryer when drying different webs. In another embodiment, the microwave dryer provides more uniform drying of a web when the field modifier is adjusted in response to a sensed condition of the web. Finally, a method of microwave heating and/or drying a web achieves a uniform heating and/or drying profile.

  16. Microwave heating of a Ba photoplasma in free expansion into a vacuum

    SciTech Connect

    Furtlehner, J.P.; Blanchet, A.; Leloutre, B.

    1995-12-31

    The microwave heating of a pulsed Ba photoplasma and its free expansion into a vacuum is studied theoretically and experimentally. The vapor production apparatus and the two step photoionization scheme have been described in a previous paper. The heating experimental device is essentially a microwave loop working in a self tuning oscillator mode composed of a transmission rectangular microwave resonator associated with a TWT power amplifier. The amplifier is coupled to the rectangular resonator by two coaxial-line probes: with a coupling coefficient very close to 1 at the input and with a coefficient equal about 10{sup -3} at the output.

  17. Microwave Heating of Functionalized Graphene Nanoribbons in Thermoset Polymers for Wellbore Reinforcement.

    PubMed

    Kim, Nam Dong; Metzger, Andrew; Hejazi, Vahid; Li, Yilun; Kovalchuk, Anton; Lee, Seoung-Ki; Ye, Ruquan; Mann, Jason A; Kittrell, Carter; Shahsavari, Rouzbeh; Tour, James M

    2016-05-25

    Here, we introduce a systematic strategy to prepare composite materials for wellbore reinforcement using graphene nanoribbons (GNRs) in a thermoset polymer irradiated by microwaves. We show that microwave absorption by GNRs functionalized with poly(propylene oxide) (PPO-GNRs) cured the composite by reaching 200 °C under 30 W of microwave power. Nanoscale PPO-GNRs diffuse deep inside porous sandstone and dramatically enhance the mechanics of the entire structure via effective reinforcement. The bulk and the local mechanical properties measured by compression and nanoindentation mechanical tests, respectively, reveal that microwave heating of PPO-GNRs and direct polymeric curing are major reasons for this significant reinforcement effect. PMID:27140722

  18. Atmospheric Pressure Plasma-Electrospin Hybrid Process for Protective Applications

    NASA Astrophysics Data System (ADS)

    Vitchuli Gangadharan, Narendiran

    2011-12-01

    Chemical and biological (C-B) warfare agents like sarin, sulfur mustard, anthrax are usually dispersed into atmosphere in the form of micro aerosols. They are considered to be dangerous weapon of mass destruction next to nuclear weapons. The airtight protective clothing materials currently available are able to stop the diffusion of threat agents but not good enough to detoxify them, which endangers the wearers. Extensive research efforts are being made to prepare advanced protective clothing materials that not only prevent the diffusion of C-B agents, but also detoxify them into harmless products thus ensuring the safety and comfort of the wearer. Electrospun nanofiber mats are considered to have effective filtration characteristics to stop the diffusion of submicron level particulates without sacrificing air permeability characteristics and could be used in protective application as barrier material. In addition, functional nanofibers could be potentially developed to detoxify the C-B warfare threats into harmless products. In this research, electrospun nanofibers were deposited on fabric surface to improve barrier efficiency without sacrificing comfort-related properties of the fabrics. Multi-functional nanofibers were fabricated through an electrospinning-electrospraying hybrid process and their ability to detoxify simulants of C-B agents was evaluated. Nanofibers were also deposited onto plasma-pretreated woven fabric substrate through a newly developed plasma-electrospinning hybrid process, to improve the adhesive properties of nanofibers on the fabric surface. The nanofiber adhesion and durability properties were evaluated by peel test, flex and abrasion resistance tests. In this research work, following tasks have been carried out: i) Controlled deposition of nanofiber mat onto woven fabric substrate Electrospun Nylon 6 fiber mats were deposited onto woven 50/50 Nylon/Cotton fabric with the motive of making them into protective material against submicron

  19. Atmospheric Pressure Plasma-Electrospin Hybrid Process for Protective Applications

    NASA Astrophysics Data System (ADS)

    Vitchuli Gangadharan, Narendiran

    2011-12-01

    Chemical and biological (C-B) warfare agents like sarin, sulfur mustard, anthrax are usually dispersed into atmosphere in the form of micro aerosols. They are considered to be dangerous weapon of mass destruction next to nuclear weapons. The airtight protective clothing materials currently available are able to stop the diffusion of threat agents but not good enough to detoxify them, which endangers the wearers. Extensive research efforts are being made to prepare advanced protective clothing materials that not only prevent the diffusion of C-B agents, but also detoxify them into harmless products thus ensuring the safety and comfort of the wearer. Electrospun nanofiber mats are considered to have effective filtration characteristics to stop the diffusion of submicron level particulates without sacrificing air permeability characteristics and could be used in protective application as barrier material. In addition, functional nanofibers could be potentially developed to detoxify the C-B warfare threats into harmless products. In this research, electrospun nanofibers were deposited on fabric surface to improve barrier efficiency without sacrificing comfort-related properties of the fabrics. Multi-functional nanofibers were fabricated through an electrospinning-electrospraying hybrid process and their ability to detoxify simulants of C-B agents was evaluated. Nanofibers were also deposited onto plasma-pretreated woven fabric substrate through a newly developed plasma-electrospinning hybrid process, to improve the adhesive properties of nanofibers on the fabric surface. The nanofiber adhesion and durability properties were evaluated by peel test, flex and abrasion resistance tests. In this research work, following tasks have been carried out: i) Controlled deposition of nanofiber mat onto woven fabric substrate Electrospun Nylon 6 fiber mats were deposited onto woven 50/50 Nylon/Cotton fabric with the motive of making them into protective material against submicron

  20. Targeting the cancer cell cycle by cold atmospheric plasma

    NASA Astrophysics Data System (ADS)

    Volotskova, O.; Hawley, T. S.; Stepp, M. A.; Keidar, M.

    2012-09-01

    Cold atmospheric plasma (CAP), a technology based on quasi-neutral ionized gas at low temperatures, is currently being evaluated as a new highly selective alternative addition to existing cancer therapies. Here, we present a first attempt to identify the mechanism of CAP action. CAP induced a robust ~2-fold G2/M increase in two different types of cancer cells with different degrees of tumorigenicity. We hypothesize that the increased sensitivity of cancer cells to CAP treatment is caused by differences in the distribution of cancer cells and normal cells within the cell cycle. The expression of γH2A.X (pSer139), an oxidative stress reporter indicating S-phase damage, is enhanced specifically within CAP treated cells in the S phase of the cell cycle. Together with a significant decrease in EdU-incorporation after CAP, these data suggest that tumorigenic cancer cells are more susceptible to CAP treatment.

  1. Cold Micro-Plasma Jets in Atmospheric Pressure Air

    NASA Astrophysics Data System (ADS)

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

    2003-10-01

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

  2. Cold Atmospheric Plasma: methods of production and application in dentistry and oncology

    PubMed Central

    2013-01-01

    Cold Atmospheric Plasma is an ionized gas that has recently been extensively studied by researchers as a possible therapy in dentistry and oncology. Several different gases can be used to produce Cold Atmospheric Plasma such as Helium, Argon, Nitrogen, Heliox, and air. There are many methods of production by which cold atmospheric plasma is created. Each unique method can be used in different biomedical areas. In dentistry, researchers have mostly investigated the antimicrobial effects produced by plasma as a means to remove dental biofilms and eradicate oral pathogens. It has been shown that reactive oxidative species, charged particles, and UV photons play the main role. Cold Atmospheric Plasma has also found a minor, but important role in tooth whitening and composite restoration. Furthermore, it has been demonstrated that Cold Atmospheric Plasma induces apoptosis, necrosis, cell detachment, and senescence by disrupting the S phase of cell replication in tumor cells. This unique finding opens up its potential therapy in oncology. PMID:24083477

  3. Properties of atmospheric pressure plasmas with microwave excitations for plasma processing

    SciTech Connect

    Nagai, Mikio; Hori, Masaru; Goto, Toshio

    2005-03-01

    Atmospheric pressure plasmas with microwave excitations were successfully produced in dielectric barrier micro plasmas employing N{sub 2}, Ar, or He gas. N{sub 2} optical emissions of the second positive system were measured for evaluating the gas temperature. The gas temperatures of the plasmas could be much less than 1000 K. Blackbody emissions were measured by Fourier transform infrared spectrometer for evaluating the electrode temperature. Temperatures of both the gas and electrode were evaluated by fitting the experimental results with calculations. The gas temperature in the N{sub 2} plasma was notably increased with the discharge time as compared with those in Ar and He plasmas. It was found that the pulsed discharge and the water-cooled electrode were effective for reducing the gas temperature. The pulsed discharge decreased the gas temperature from 900 to 600 K, and the water-cooled electrode decreased the gas temperature by more than 200 K. Controlling the temperature of the electrodes was the most effective technique to reduce the gas temperature, because the gas temperature was in equilibrium with the electrode temperature.

  4. Diagnostics of plasma-biological surface interactions in low pressure and atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Ishikawa, Kenji; Hori, Masaru

    2014-08-01

    Mechanisms of plasma-surface interaction are required to understand in order to control the reactions precisely. Recent progress in atmospheric pressure plasma provides to apply as a tool of sterilization of contaminated foodstuffs. To use the plasma with safety and optimization, the real time in situ detection of free radicals - in particular dangling bonds by using the electron-spin-resonance (ESR) technique has been developed because the free radical plays important roles for dominantly biological reactions. First, the kinetic analysis of free radicals on biological specimens such as fungal spores of Penicillium digitatum interacted with atomic oxygen generated plasma electric discharge. We have obtained information that the in situ real time ESR signal from the spores was observed and assignable to semiquinone radical with a g-value of around 2.004 and a line width of approximately 5G. The decay of the signal was correlated with a link to the inactivation of the fungal spore. Second, we have studied to detect chemical modification of edible meat after the irradiation. Using matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS) and ESR, signals give qualification results for chemical changes on edible liver meat. The in situ real-time measurements have proven to be a useful method to elucidate plasma-induced surface reactions on biological specimens.

  5. Plasma penetration depth and mechanical properties of atmospheric plasma-treated 3D aramid woven composites

    NASA Astrophysics Data System (ADS)

    Chen, X.; Yao, L.; Xue, J.; Zhao, D.; Lan, Y.; Qian, X.; Wang, C. X.; Qiu, Y.

    2008-12-01

    Three-dimensional aramid woven fabrics were treated with atmospheric pressure plasmas, on one side or both sides to determine the plasma penetration depth in the 3D fabrics and the influences on final composite mechanical properties. The properties of the fibers from different layers of the single side treated fabrics, including surface morphology, chemical composition, wettability and adhesion properties were investigated using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurement and microbond tests. Meanwhile, flexural properties of the composites reinforced with the fabrics untreated and treated on both sides were compared using three-point bending tests. The results showed that the fibers from the outer most surface layer of the fabric had a significant improvement in their surface roughness, chemical bonding, wettability and adhesion properties after plasma treatment; the treatment effect gradually diminished for the fibers in the inner layers. In the third layer, the fiber properties remained approximately the same to those of the control. In addition, three-point bending tests indicated that the 3D aramid composite had an increase of 11% in flexural strength and 12% in flexural modulus after the plasma treatment. These results indicate that composite mechanical properties can be improved by the direct fabric treatment instead of fiber treatment with plasmas if the fabric is less than four layers thick.

  6. 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.

  7. Integrin activation by a cold atmospheric plasma jet

    NASA Astrophysics Data System (ADS)

    Volotskova, Olga; Stepp, Mary Ann; Keidar, Michael

    2012-05-01

    Current breakthrough research on cold atmospheric plasma (CAP) demonstrates that CAP has great potential in various areas, including medicine and biology, thus providing a new tool for living tissue treatment. In this paper, we explore potential mechanisms by which CAP alters cell migration and influences cell adhesion. We focus on the study of CAP interaction with fibroblasts and corneal epithelial cells. The data show that fibroblasts and corneal epithelial cells have different thresholds (treatment times) required to achieve maximum inhibition of cell migration. Both cell types reduced their migration rates by ˜30-40% after CAP compared to control cells. Also, the impact of CAP treatment on cell migration and persistence of fibroblasts after integrin activation by MnCl2, serum starvation or replating cells onto surfaces coated with integrin ligands is assessed; the results show that activation by MnCl2 or starvation attenuates cells’ responses to plasma. Studies carried out to assess the impact of CAP treatment on the activation state of β1 integrin and focal adhesion size by using immunofluorescence show that fibroblasts have more active β1 integrin on their surface and large focal adhesions after CAP treatment. Based on these data, a thermodynamic model is presented to explain how CAP leads to integrin activation and focal adhesion assembly.

  8. Development of Simplified Atmospheric-Pressure Plasma Nitriding

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hirofumi; Ichiki, Ryuta; Maeda, Akihide; Yamanouchi, Kenta; Akamine, Shuichi; Kanazawa, Seiji; Oita University Team

    2015-09-01

    Nitriding treatment is one of the surface hardening technologies, applied to dies and automobile components. In recent industry, low-pressure nitriding treatment using vacuum system is mainstream. On the other hand, we have originally developed an atmospheric-pressure plasma nitriding which do not need vacuum system. However we needed an air-tight container to purge residual oxygen and external heater to control treatment temperature. To make this technique practical, we addressed to construct a simplified treatment system, where treatment temperature is controlled by thermal plasma itself and oxygen purging is achieved by a simple cover. This means that any air-tight container and external heater is not necessary. As a result, surface temperature is controlled by changing treatment gap from nozzle tip to steel surface. We succeeded in controlling well thickness of hardened layer by adjusting treatment temperature even in such a simplified system. In the conference, we also discuss experimental results for hardening complex shaped materials by using our simplified nitriding.

  9. Atmospheric pressure nonthermal plasmas for bacterial biofilm prevention and eradication.

    PubMed

    Ermolaeva, Svetlana A; Sysolyatina, Elena V; Gintsburg, Alexander L

    2015-01-01

    Biofilms are three-dimensional structures formed by surface-attached microorganisms and their extracellular products. Biofilms formed by pathogenic microorganisms play an important role in human diseases. Higher resistance to antimicrobial agents and changes in microbial physiology make treating biofilm infections very complex. Atmospheric pressure nonthermal plasmas (NTPs) are a novel and powerful tool for antimicrobial treatment. The microbicidal activity of NTPs has an unspecific character due to the synergetic actions of bioactive components of the plasma torch, including charged particles, reactive species, and UV radiation. This review focuses on specific traits of biofilms, their role in human diseases, and those effects of NTP that are helpful for treating biofilm infections. The authors discuss NTP-based strategies for biofilm control, such as surface modifications to prevent bacterial adhesion, killing bacteria in biofilms, and biofilm destruction with NTPs. The unspecific character of microbicidal activity, proven polymer modification and destruction abilities, low toxicity for human tissues and absence of long-living toxic compounds make NTPs a very promising tool for biofilm prevention and control. PMID:25869456

  10. Gas flow dependence of atmospheric pressure plasma needle discharge characteristics

    NASA Astrophysics Data System (ADS)

    Qian, Muyang; Yang, Congying; Liu, Sanqiu; Chen, Xiaochang; Ni, Gengsong; Wang, Dezhen

    2016-04-01

    In this paper, a two-dimensional coupled model of neutral gas flow and plasma dynamics is presented to explain the gas flow dependence of discharge characteristics in helium plasma needle at atmospherics pressure. The diffusional mixing layer between the helium jet core and the ambient air has a moderate effect on the streamer propagation. The obtained simulation results present that the streamer shows the ring-shaped emission profile at a moderate gas flow rate. The key chemical reactions which drive the streamer propagation are electron-impact ionization of helium neutral, nitrogen and oxygen molecules. At a moderate gas flow rate of 0.5 slm, a significant increase in propagation velocity of the streamer is observed due to appropriate quantity of impurities air diffuse into the helium. Besides, when the gas flow rate is below 0.35 slm, the radial density of ground-state atomic oxygen peaks along the axis of symmetry. However, when the gas flow rate is above 0.5 slm, a ring-shaped density distribution appears. The peak density is on the order of 1020 m-3 at 10 ns in our work.

  11. Cold Atmospheric Plasma as an alternative therapy for cancer therapies

    NASA Astrophysics Data System (ADS)

    Volotskova, Olga; Hawley, Teresa; Stepp, Mary Ann; Keidar, Michael

    2012-10-01

    CAP (cold atmospheric plasma) is a technology, which is based on quasi-neutral ionized gas (plasma at low temperatures), which is being evaluated as an alternative or addition to existing cancer therapies. A recent study shows that CAP treatment can cause a significant reduction in tumor size in vivo. Thus the purpose of this study is to begin to identify the mechanism by which cancer cells are killed by CAP, i.e. to identify the mechanism of CAP action. CAP induced a robust ˜2-fold G2/M increase in two different types of cancer cells with different degrees of tumorigenicity. We hypothesize that the increased sensitivity of cancer cells to CAP treatment is caused by differences in the distribution of cancer cells and normal cells within the cell cycle. The expression of γH2A.X (pSer139), an oxidative stress reporter indicating S-phase damage, is enhanced specifically within CAP treated cells in the S phase of the cell cycle together with significant decrease in EdU-signal of DNA-replicating cells. Our data suggest that more tumorigenic cancer cells are better susceptible to CAP treatment.

  12. The solvation of electrons by an atmospheric-pressure plasma

    PubMed Central

    Rumbach, Paul; Bartels, David M.; Sankaran, R. Mohan; Go, David B.

    2015-01-01

    Solvated electrons are typically generated by radiolysis or photoionization of solutes. While plasmas containing free electrons have been brought into contact with liquids in studies dating back centuries, there has been little evidence that electrons are solvated by this approach. Here we report direct measurements of solvated electrons generated by an atmospheric-pressure plasma in contact with the surface of an aqueous solution. The electrons are measured by their optical absorbance using a total internal reflection geometry. The measured absorption spectrum is unexpectedly blue shifted, which is potentially due to the intense electric field in the interfacial Debye layer. We estimate an average penetration depth of 2.5±1.0 nm, indicating that the electrons fully solvate before reacting through second-order recombination. Reactions with various electron scavengers including H+, NO2−, NO3− and H2O2 show that the kinetics are similar, but not identical, to those for solvated electrons formed in bulk water by radiolysis. PMID:26088017

  13. Plasma-polymerized methyl methacrylate via intense and highly energetic atmospheric pressure micro-plasma for bio-medical applications

    NASA Astrophysics Data System (ADS)

    Park, Choon-Sang; Ballato, John; Kim, Sung-O.; Clemson University Team

    2013-09-01

    Poly (methyl methacrylate), PMMA, has been widely used as a biocompatible material in bone cement, dental fillings, and many other bio-related applications. Vacuum plasmas and radio frequency (RF) atmospheric plasmas are the most common methods for depositing plasma-derived thin films and nanoparticles. However, the necessary equipment is difficult to operate and maintain as well as being large and expensive. Here, we report the use of a novel intense and highly energetic atmospheric pressure plasma jet array using direct plasma jet-to-jet coupling effects to deposit high quality plasma-polymerized MMA (PPMMA) for bio-medical applications. The newly proposed atmospheric pressure micro-plasma jet array device can generate the intense plasma mode with a strong plasma emission and high plasma particle energy. PPMMA was successfully deposited on a variety of substrates and characterized by SEM, AFM, and FT-IR. The micro-plasma jet is obtained at a sinusoidal voltage with a peak value of 30 kV and frequency of 35 kHz. Argon gas was employed as the discharge gas for plasma generation and its flow rate was in the range of 2230 sccm, Methyl methacrylate (MMA) monomer was vaporized by means of a glass bubbler which was supplied by argon gas with flow rates in the range of 268 sccm from room temperature to 400°C. The deposited PPMMA thin films were flexible, transparent, thin, and strong on metal substrates.

  14. Experimental study of temperature distribution in rubber material during microwave heating and vulcanization process

    NASA Astrophysics Data System (ADS)

    Chen, Hai-Long; Li, Tao; Liang, Yun; Sun, Bin; Li, Qing-Ling

    2016-07-01

    Microwave technology has been employed to heat sheet rubber, the optical fiber temperature online monitor and optical fiber temperature sensor have been employed to measure the temperature in sheet rubber. The temperature of sheet rubber increased with increase of heating time during microwave heating process in which the maximum of temperature was <100 °C and microwave vulcanization process in which the maximum of temperature was <150 °C, the curves of temperature-time presented nonlinearity. The rate of temperature rising in central zone of sheet rubber was higher than the rate of temperature rising in marginal zone of sheet rubber, and the final temperature in central zone of sheet rubber was also higher than the final temperature in marginal zone of sheet rubber. In the microwave heating and vulcanization process of sheet rubber, the maximum of rate of temperature rising and the maximum of temperature belong to the central zone of sheet rubber, so the distribution of electric field was uneven in heating chamber, which led to the uneven temperature distribution of sheet rubber. The higher electric field intensity value converges on the central zone of sheet rubber.

  15. Microwave-heating synthesis and sensing applications of bright gold nanoclusters

    SciTech Connect

    He, Ding-Fei; Xiang, Yang; Wang, Xu; Yu, Xue-Feng

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We establish a microwave-heating method to synthesize protein-stabilized Au nanoclusters. Black-Right-Pointing-Pointer The obtained Au nanoclusters show bright red fluorescence. Black-Right-Pointing-Pointer The Au nanoclusters can be used as efficient fluorescence probe for Cu{sup 2+} ion sensing. -- Abstract: A rapid microwave-heating method has been developed for the synthesis of bright Au nanoclusters by using bull serum albumin as the template in an aqueous environment. The reaction time needed is only 7.0 min, and the weight of the products at one batch can reach 15 g. The Au nanoclusters exhibit bright fluorescence at {approx}613 nm with quantum yield of {approx}6.0%. By adjusting the pH value, the products can be controlled to precipitate or re-disperse in aqueous solution. Furthermore, the Au nanoclusters have exhibited high sensitivity and selectivity in the determination of Cu{sup 2+} ions in water. These results suggest an efficient method for obtaining metal nanoclusters for the detection and sensing applications.

  16. Thermoelectric properties of bulk MoSi2 synthesized by solid state microwave heating

    NASA Astrophysics Data System (ADS)

    Lan, Yu; Xie, Mianyu; Ouyang, Ting; Yue, Song

    2016-07-01

    In this research, single phase α-MoSi2 was prepared by solid state hybrid microwave heating within 90 min at relatively low temperature 1273 K. Such precursor powders were then ball milled and sintered by microwave heating at different temperatures. The thermoelectric (TE) properties of MoSi2 bulks were investigated in the temperature range of 300-673 K. When the sintering temperature increases from 973 K to 1273 K, the electrical resistivity decreases significantly and the Seebeck coefficients increase obviously, leading to the maximum TE powder factor of 6.2 × 10‑6Wm‑1K‑2 at 673 K. These results demonstrate the feasibility of high efficient and economical synthesis of MoSi2 by microwave heating technique, with the final products having comparable TE performance in comparison to those from typical methods with long duration and energy-extensive consumption.

  17. Micro-Biocidal Activity of Yeast Cells by Needle Plasma Irradiation at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Kurumi, Satoshi; Takahashi, Hideyuki; Taima, Tomohito; Suzuki, Kaoru; Hirose, Hideharu; Masutani, Shigeyuki

    In this study, we report on the biocidal activity technique by needle helium plasma irradiation at atmospheric pressure using borosilicate capillary nozzle to apply for the oral surgery. The diameter of needle plasma was less than 50 µm, and temperature of plasma irradiated area was less than body temperature. Needle plasma showed emission due to OH and O radical. Raman spectra and methylene blue stain showed yeast cells were inactivated by needle plasma irradiation.

  18. Atmospheric Plasma Deposition of Diamond-like Carbon Coatings

    SciTech Connect

    Ladwig, Angela

    2008-01-23

    material that may be treated. The deposition of DLC at atmospheric pressure has been demonstrated by several researchers. Izake, et al [53] and Novikov and Dymont [54] have demonstrated an electrochemical process that is carried out with organic compounds such as methanol and acetylene dissolved in ammonia. This process requires that the substrates be immersed in the liquid [53-54]. The atmospheric pressure deposition of DLC was also demonstrated by Kulik, et al. utilizing a plasma torch. However, this process requires operating temperatures in excess of 800 oC [55]. In this report, we investigate the deposition of diamond-like carbon films using a low temperature, atmospheric pressure plasma-enhanced chemical vapor deposition (PECVD) process. The films were characterized by solid-state carbon-13 nuclear magnetic resonance (13C NMR) and found to have a ratio of sp2 to sp3 carbon of 43 to 57%. The films were also tested for adhesion, coefficient of friction, and dielectric strength.

  19. Cold atmospheric plasma - A new technology for spacecraft component decontamination

    NASA Astrophysics Data System (ADS)

    Shimizu, Satoshi; Barczyk, Simon; Rettberg, Petra; Shimizu, Tetsuji; Klaempfl, Tobias; Zimmermann, Julia L.; Hoeschen, Till; Linsmeier, Christian; Weber, Peter; Morfill, Gregor E.; Thomas, Hubertus M.

    2014-01-01

    Cold atmospheric plasma (CAP) based on the Surface Micro-Discharge (SMD) technology was investigated for inactivation of different bacteria and endospores. The used technique was developed to serve as an alternative method for the decontamination of spacecraft components based on the COSPAR planetary protection policy where currently the dry heat microbial reduction method is the only applicable way to satisfy the required demands. However it is known, that dry heat can thermally damage sophisticated components installed on the device. Therefore, the development of a low temperature sterilization system is one of the high priority issues for upcoming space missions in the extraterrestrial field. In the study presented here, the vegetative bacteria Escherichia coli and Deinococcus radiodurans and several types of bacterial endospores - including Bacillus atrophaeus, Bacillus safensis, Bacillus megaterium, Bacillus megaterium 2c1 and Bacillus thuringiensis E24 - were inactivated by exposing them indirectly i.e. only to the reactive gases produced by the SMD electrode at room temperature. The results showed a 5 log inactivation for E. coli after 10 min of exposure. In contrast D. radiodurans proved to be more resistant resulting in a reduction of 3 log after exposure of 30 min. More than 6 log reductions were achieved for B. safensis, B. megaterium and B. megaterium 2c1 after 90 min of exposure. Furthermore the applicability of the used CAP system for spacecraft decontamination according to the planetary protection policy was investigated. This included also the investigation of the inactivation homogeneity by the plasma gas, the control of the temperature at the area of interest, the measurement of the O3 density in the treatment region and the detailed investigation of the effects of the exposure on different materials.

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

    NASA Astrophysics Data System (ADS)

    Langlois-Bertrand, Emilie; de Izarra, Charles

    2011-10-01

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

  1. Biomedical Applications of Low Temperature Atmospheric Pressure Plasmas to Cancerous Cell Treatment and Tooth Bleaching

    NASA Astrophysics Data System (ADS)

    Lee, Jae Koo; Kim, Myoung Soo; Byun, June Ho; Kim, Kyong Tai; Kim, Gyoo Cheon; Park, Gan Young

    2011-08-01

    Low temperature atmospheric pressure plasmas have attracted great interests and they have been widely applied to biomedical applications to interact with living tissues, cells, and bacteria due to their non-thermal property. This paper reviews the biomedical applications of low temperature atmospheric pressure plasmas to cancerous cell treatment and tooth bleaching. Gold nanoparticles conjugated with cancer-specific antibodies have been introduced to cancerous cells to enhance selective killing of cells, and the mechanism of cell apoptosis induced by plasma has been investigated. Tooth exposed to helium plasma jet with hydrogen peroxide has become brighter and the productions of hydroxyl radicals from hydrogen peroxide have been enhanced by plasma exposure.

  2. Effects of atmospheric dusty plasma generated by natural radioactivity on the atmosphere thermodynamics and electrodynamics

    NASA Astrophysics Data System (ADS)

    Pulinets, Sergey; Ouzounov, Dimitar

    Natural radioactivity of the Earth through ionization creates a large number of new ions in the boundary layer of atmosphere from the ground surface up to near 1 km altitude. In specific conditions the ion concentration can reach 10 (6) -10 (7) cm (-3) . This sharp increase of ion concentration leads to the process of so called Ion Induced Nucleation (IIN) when due to ion's hydration the large complex ion clusters are formed with the very low recombination rate, i.e. we deal with formation of dusty atmospheric plasma in the boundary layer. Our theoretical estimates and experimental results of ground based and remote sensing satellite monitoring revealed two main consequences of IIN: release of large amount of the latent heat leading to the changes of air temperature and humidity, and sharp changes of air conductivity in the vertical column of the Global Electric Circuit (GEC) leading to formation of large scale irregularities of electron concentration in the ionosphere. The mechanism has universal character and its effects are observed in different natural and anthropogenic disasters like hurricanes, earthquakes, volcano eruption, artificial ionization, emergencies at atomic power plants, etc. Experimental evidences for many cases demonstrating effects of IIN are presented.

  3. Assessment of Atmospheric Pressure Plasma Treatment for Implant Osseointegration

    PubMed Central

    Danna, Natalie R.; Beutel, Bryan G.; Tovar, Nick; Witek, Lukasz; Marin, Charles; Granato, Rodrigo; Suzuki, Marcelo; Coelho, Paulo G.

    2015-01-01

    This study assessed the osseointegrative effects of atmospheric pressure plasma (APP) surface treatment for implants in a canine model. Control surfaces were untreated textured titanium (Ti) and calcium phosphate (CaP). Experimental surfaces were their 80-second air-based APP-treated counterparts. Physicochemical characterization was performed to assess topography, surface energy, and chemical composition. One implant from each control and experimental group (four in total) was placed in one radius of each of the seven male beagles for three weeks, and one implant from each group was placed in the contralateral radius for six weeks. After sacrifice, bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were assessed. X-ray photoelectron spectroscopy showed decreased surface levels of carbon and increased Ti and oxygen, and calcium and oxygen, posttreatment for Ti and CaP surfaces, respectively. There was a significant (P < 0.001) increase in BIC for APP-treated textured Ti surfaces at six weeks but not at three weeks or for CaP surfaces. There were no significant (P = 0.57) differences for BAFO between treated and untreated surfaces for either material at either time point. This suggests that air-based APP surface treatment may improve osseointegration of textured Ti surfaces but not CaP surfaces. Studies optimizing APP parameters and applications are warranted. PMID:26090443

  4. Use of Atmospheric Glow Discharge Plasma to Modify Spaceport Materials

    NASA Technical Reports Server (NTRS)

    Trigwell, S.; Shuerger, A. C.; Buhler, C. R.; Calle, C. J.

    2006-01-01

    Numerous materials used in spaceport operations require stringent evaluation before they can be utilized. It is critical for insulative polymeric materials that any surface charge be dissipated as rapidly as possible to avoid Electrostatic Discharges (ESD) that could present a danger. All materials must pass the Kennedy Space Center (KSC) standard electrostatic test [1]; however several materials that are considered favorable for Space Shuttle and International Space Station use have failed. Moreover, to minimize contamination of Mars spacecraft, spacecraft are assembled under cleanroom conditions and specific cleaning and sterilizing procedures are required for all materials. However, surface characteristics of these materials may allow microbes to survive by protecting them from sterilization and cleaning techniques. In this study, an Atmospheric Pressure Glow Discharge Plasma (APGD) [2] was used to modify the surface of several materials. This allowed the materials surface to be modified in terms of hydrophilicity, roughness, and conductivity without affecting the bulk properties. The objectives of this study were to alter the surface properties of polymers for improved electrostatic dissipation characteristics, and to determine whether the consequent surface modification on spaceport materials enhanced or diminished microbial survival.

  5. In situ growth of silver nanoparticles on TEMPO-oxidized jute fibers by microwave heating.

    PubMed

    Cao, Xinwang; Ding, Bin; Yu, Jianyong; Al-Deyab, Salem S

    2013-01-30

    Cellulose fibers deposited with metallic nanoparticles as one kind of renewable, biocompatible and antimicrobial nanomaterials evoke much interest because of their versatility in various applications. Herein, for the first time, a facile, simple and rapid method was developed to fabricate TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) selectively oxidized jute fibers in situ deposited with silver nanoparticles in the absence of reducing reagents. The average size of silver nanoparticles deposited on the fibers is 50.0 ± 2.0 nm by microwave heating for 5 min and 90.0 ± 4.7 nm for 10 min heating sample, respectively. The versatile jute-silver nanoparticles nanocomposites with superior thermal stability and high crystallinity would be particularly useful for applications in the public health care and biomedical fields. PMID:23218337

  6. Dielectric properties of cereals at frequencies useful for processes with microwave heating.

    PubMed

    Torrealba-Meléndez, Richard; Sosa-Morales, María Elena; Olvera-Cervantes, José Luis; Corona-Chávez, Alonso

    2015-12-01

    Dielectric properties of barley, corn (white and yellow), sorghum, and wheat at microwave frequencies for heating purpose were analyzed. Properties were determined at 915, 2450 and 5800 MHz with the free space transmission method in the cereals at 20, 30, 40, 50 and 60 °C. ε´ and ε"of all the cereals decreased with increasing frequency. ε´ slightly increased with temperature, while ε "remained practically constant for all the cereals in the temperature range from 20 to 60 °C. Penetration depth decreased with increasing frequency for all the samples, and increased with increasing temperature at 915 MHz, except for barley. These results are useful for further microwave heating applications for the studies on cereals. PMID:26604422

  7. Evaluation the microwave heating of spinel crystals in high-level waste glass

    SciTech Connect

    Christian, J. H.; Washington, A. L.

    2015-08-18

    In this report, the microwave heating of a crystal-free and a partially (24 wt%) trevorite-crystallized waste glass simulant were evaluated. The results show that a 500 mg piece of partially crystallized waste glass can be heated from room-temperature to above 1600 °C (as measured by infrared radiometry) within 2 minutes using a single mode, highly focused, 2.45 GHz microwave, operating at 300 W. X-ray diffraction measurements show that the partially crystallized glass experiences an 87 % reduction in trevorite following irradiation and thermal quenching. When a crystal-free analogue of the same waste glass simulant composition is exposed to the same microwave radiation it could not be heated above 450 °C regardless of the heating time.

  8. A Study on Uniform Heating of Solid Foods and High Viscosity Foods by Microwave Heating

    NASA Astrophysics Data System (ADS)

    Suga, Ryosuke; Hashimoto, Osamu; Ijuin, Taichi; Takatomi, Tetsuya

    In this paper, an microwave oven for disinfectant one application has been modeled by FDTD-HTE Method and reserched uniform heating of solution model simulated solid food and high viscosity food. We suggest two technique for uniform heating. First one is that water film is arranged around the food for reducing local heating of edge heating. Second one is that food is heated by using both steam and microwave. As a result, 2mm water film lower temperature of high temperature part in the food efficiently, by using uniform heating technique using water film. And we confirmed that 33% of uneven heating is improved. Moreover, we confirmed that steam heated edge of food and microwave heated center of food, and food is gone to about 60 degrees centigrade through uniform technique using both Steam and microwave.

  9. Numerical modeling of continuous flow microwave heating: a critical comparison of COMSOL and ANSYS.

    PubMed

    Salvi, D; Boldor, Dorin; Ortego, J; Aita, G M; Sabliov, C M

    2010-01-01

    Numerical models were developed to simulate temperature profiles in Newtonian fluids during continuous flow microwave heating by one way coupling electromagnetism, fluid flow, and heat transport in ANSYS 8.0 and COMSOL Multiphysics v3.4. Comparison of the results from the COMSOL model with the results from a pre-developed and validated ANSYS model ensured accuracy of the COMSOL model. Prediction of power Loss by both models was in close agreement (5-13% variation) and the predicted temperature profiles were similar. COMSOL provided a flexible model setup whereas ANSYS required coupling incompatible elements to transfer load between electromagnetic, fluid flow, and heat transport modules. Overall, both software packages provided the ability to solve multiphysics phenomena accurately. PMID:21721467

  10. Scale-up of the nitridation and sintering of silicon preforms using microwave heating

    SciTech Connect

    Kiggans, J.O. Jr.; Tiegs, T.N.; Davisson, C.C.; Morrow, M.S.; Garvey, G.J.

    1996-05-01

    Scale-up studies were performed in which microwave heating was used to fabricate reaction-bonded silicon nitride and sintered reaction-bonded silicon nitride (SRBSN). Tests were performed in both a 2.45 GHz, 500 liter and a 2.45 GHz, 4,000 liter multimode cavities. A variety of sizes, shapes, and compositions of silicon preforms were processed in the studies, including bucket tappets and clevis pins for diesel engines. Up to 230 samples were processed in a single microwave furnace run. Data were collected which included weight gains for nitridation experiments, and final densities for nitridation and sintering experiments. For comparison, nitridation and sintering studies were performed using a conventional resistance-heated furnace.

  11. Rapid PCR amplification using a microfluidic device with integrated microwave heating and air impingement cooling.

    PubMed

    Shaw, Kirsty J; Docker, Peter T; Yelland, John V; Dyer, Charlotte E; Greenman, John; Greenway, Gillian M; Haswell, Stephen J

    2010-07-01

    A microwave heating system is described for performing polymerase chain reaction (PCR) in a microfluidic device. The heating system, in combination with air impingement cooling, provided rapid thermal cycling with heating and cooling rates of up to 65 degrees C s(-1) and minimal over- or under-shoot (+/-0.1 degrees C) when reaching target temperatures. In addition, once the required temperature was reached it could be maintained with an accuracy of +/-0.1 degrees C. To demonstrate the functionality of the system, PCR was successfully performed for the amplification of the Amelogenin locus using heating rates and quantities an order of magnitude faster and smaller than current commercial instruments. PMID:20414500

  12. Microwave heating: Industrial applications. September 1986-September 1989 (Citations from the COMPENDEX data base). Report for September 1986-September 1989

    SciTech Connect

    Not Available

    1989-10-01

    This bibliography contains citations concerning industrial uses and design of microwave heating equipment. Included are heating and drying of paper, industrial process heat, vulcanization, textile processing, metallurgical heat for sintering and ceramic manufacturing, food processing, and curing of polymers. (This updated bibliography contains 116 citations, 11 of which are new entries to the previous edition.)

  13. Effect of particle size and relative density on powdery Fe3O4 microwave heating.

    PubMed

    Hayashi, Miyuki; Yokoyama, Yuki; Nagata, Kazuhiro

    2010-01-01

    In recent years, microwave energy is expected to be a heat source of high temperature process aiming for CO2 reduction and energy conservation owing to the possibility of volumetric heating. In order to examine the applicability of microwave heating to ironmaking, it is important to investigate the microwave heating of raw materials of ironmaking such as Fe3O4. In this study, the effect of particle size and relative density on microwave absorptivity of powdery Fe3O4 was elucidated by the heating curves. Powdery Fe3O4 samples having different particle sizes and relative densities and bulk Fe3O4 samples were heated at the positions of the H (magnetic) and E (electric) field maxima in a 2.45 GHz single-mode microwave cavity. Sample temperatures abruptly increase and become constant after a while. At a constant temperature, the energy balance is attained, i.e., the rate of microwave energy absorption is equal to the rate of thermal energy dissipation. Assuming that the thermal energy dissipation rate due to convection and radiation heat fluxes is only a function of the sample temperature, the microwave absorptivity could be evaluated by the temperature at the steady state. It has been found that the microwave absorptivity of Fe3O4 powder decreases with an increase in relative density. On the other hand, the microwave absorptivity hardly depends on the particle size, which may be due to its quite a large penetration depth of Fe3O4 compared to metal. PMID:21721468

  14. The microwave heating of two-dimensional slabs with small Arrhenius absorptivity

    NASA Astrophysics Data System (ADS)

    Liu, B.; Marchant, T. R.

    1999-04-01

    The microwave heating of two-dimensional slabs in a long rectangular waveguide propagating the TE10 mode is examined. The temperature dependency of the electrical conductivity and the thermal absorptivity is assumed to be governed by the Arrhenius law, while both the electrical permittivity and the magnetic permeability are assumed constant. The governing equations are the forced heat equation and the steady-state version of Maxwell's equation while the boundary conditions take into account both convective and radiative heat loss. Approximate analytical solutions, valid for small thermal absorptivity, are found for the temperature and the electric-field amplitude using the Galerkin method. As the Arrhenius law is not amenable analytically, it is approximated by a rational-cubic function. At the steady state the temperature versus power relationship is found to be multivalued; at the critical power level thermal runaway occurs when the temperature jumps from the lower (cool) temperature branch to the upper (hot) temperature branch of the solution. In the steady-state limit the approximate analytical solutions are compared with the numerical solutions of the governing equations for various special cases. These are the limits of small and large heat loss and an intermediate case involving radiative heat loss. Results are also presented for a case where differential cooling occurs on the different sides on the slab. An alternative heating scenario, where one end of the waveguide is blocked by a short, is also considered. The approximate solutions are found for this geometry and compared in the small Biot-number limit to Kriegsmann (1997). Also, a control process is presented, which allows thermal runaway to be avoided and the desired final steady state to be reached. Various special cases of the feedback parameters associated with the control process are examined. Keywords:microwave heating; thermal runway; Arrhenius law; control process; small thermal absorptivity

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

    SciTech Connect

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

    2013-06-15

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

  16. Deactivation of Enterococcus Faecalis Bacteria by an Atmospheric Cold Plasma Brush

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Huang, Jun; Du, Ning; Liu, Xiao-Di; Lv, Guo-Hua; Wang, Xing-Quan; Zhang, Guo-Ping; Guo, Li-Hong; Yang, Si-Ze

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed and used to treat enterococcus faecalis bacteria. The results show that the efficiency of the inactivation process by helium plasma is dependent on applied power and exposure time. After plasma treatments, the cell structure and morphology changes can be observed by scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  17. Experimental study on the emission spectra of microwave plasma at atmospheric pressure

    SciTech Connect

    Zhang, Boya; Wang, Qiang; Zhang, Guixin; Liao, Shanshan

    2014-01-28

    An experimental study on microwave plasma at atmospheric pressure was conducted by employing optical emission spectroscopy. Based on a microwave plasma generation device developed for nanoparticle synthesis, we studied the influence of input microwave power and gas flow rate on the optical emission behaviors and electron temperature of plasma using Ar, He, and N{sub 2} as working gas, respectively. The physics behind these behaviors was discussed. The results are useful in characterizing microwave plasma at atmospheric pressure and can be used for improving nanoparticle synthesis system for commercial use in the future.

  18. Spectroscopic diagnosis of an atmospheric-pressure waveguide-based microwave N2-Ar plasma torch

    NASA Astrophysics Data System (ADS)

    Li, Shou-Zhe; Chen, Chuan-Jie; Zhang, Xin; Zhang, Jialiang; Wang, Yong-Xing

    2015-04-01

    An atmospheric-pressure N2-Ar plasma is investigated by means of optical emission spectroscopic diagnosis concerning the variation of its fundamental parameters, electron density and plasma temperature, and concentrations of ionized molecular nitrogen, atomic nitrogen, and excited argon with the tuning variables, such as the input power and the ratio of N2 in N2-Ar mixture gas, in the discharge region of the plasma torch. Moreover, qualitative discussions are delivered with respect to the mechanisms for nitrogen dissociation and influence of the Ar component on the N2 plasma discharge at atmospheric pressure.

  19. Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition

    SciTech Connect

    Chen Wei; Huang Jun; Wang Xingquan; Lv Guohua; Zhang Guoping; Du Ning; Liu Xiaodi; Guo Lihong; Yang Size

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O{sub 2} plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O{sub 2} plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O{sub 2} (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  20. Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Huang, Jun; Du, Ning; Liu, Xiao-Di; Wang, Xing-Quan; Lv, Guo-Hua; Zhang, Guo-Ping; Guo, Li-Hong; Yang, Si-Ze

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O2 plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O2 plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O2 (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  1. CO2 dissociation in an atmospheric pressure plasma/catalyst system: a study of efficiency

    NASA Astrophysics Data System (ADS)

    Spencer, L. F.; Gallimore, A. D.

    2013-02-01

    The continual and increasing use of fossil fuels throughout the world has advanced concerns of atmospheric carbon dioxide (CO2) concentrations, causing a swell of scientific interest to ease the predicted effects of global warming. This work experimentally investigates the conversion of CO2 to carbon monoxide (CO) and oxygen in an atmospheric pressure microwave plasma/catalyst system. Diagnostics such as mass spectrometry and optical emission spectroscopy are used to identify the gas species present after plasma treatment and to measure plasma temperatures. The CO2 gas is first treated with plasma alone, and is then treated with a combination of plasma and rhodium (Rh) catalyst material. While the plasma system alone is able to achieve a 20% energy efficiency, the Rh catalyst actually causes a drop in efficiency due to reverse reactions occurring on the surface. The plasma temperature measurements indicate thermal equilibrium between Tr and Tv around 6000-7000 K.

  2. Comparison of free radicals formation induced by cold atmospheric plasma, ultrasound, and ionizing radiation.

    PubMed

    Rehman, Mati Ur; Jawaid, Paras; Uchiyama, Hidefumi; Kondo, Takashi

    2016-09-01

    Plasma medicine is increasingly recognized interdisciplinary field combining engineering, physics, biochemistry and life sciences. Plasma is classified into two categories based on the temperature applied, namely "thermal" and "non-thermal" (i.e., cold atmospheric plasma). Non-thermal or cold atmospheric plasma (CAP) is produced by applying high voltage electric field at low pressures and power. The chemical effects of cold atmospheric plasma in aqueous solution are attributed to high voltage discharge and gas flow, which is transported rapidly on the liquid surface. The argon-cold atmospheric plasma (Ar-CAP) induces efficient reactive oxygen species (ROS) in aqueous solutions without thermal decomposition. Their formation has been confirmed by electron paramagnetic resonance (EPR) spin trapping, which is reviewed here. The similarities and differences between the plasma chemistry, sonochemistry, and radiation chemistry are explained. Further, the evidence for free radical formation in the liquid phase and their role in the biological effects induced by cold atmospheric plasma, ultrasound and ionizing radiation are discussed. PMID:27085689

  3. 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.

  4. Intracellular effects of atmospheric-pressure plasmas on melanoma cancer cells

    SciTech Connect

    Ishaq, M.; Bazaka, K.; Ostrikov, K.

    2015-12-15

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown as a promising tool for cancer treatment. The mechanism of the plasma action is attributed to generation of reactive oxygen and nitrogen species, electric fields, charges, and photons. The relative importance of different modes of action of atmospheric-pressure plasmas depends on the process parameters and specific treatment objects. Hence, an in-depth understanding of biological mechanisms that underpin plasma-induced death in cancer cells is required to optimise plasma processing conditions. Here, the intracellular factors involved in the observed anti-cancer activity in melanoma Mel007 cells are studied, focusing on the effect of the plasma treatment dose on the expression of tumour suppressor protein TP73. Over-expression of TP73 causes cell growth arrest and/or apoptosis, and hence can potentially be targeted to enhance killing efficacy and selectivity of the plasma treatment. It is shown that the plasma treatment induces dose-dependent up-regulation of TP73 gene expression, resulting in significantly elevated levels of TP73 RNA and protein in plasma-treated melanoma cells. Silencing of TP73 expression by means of RNA interference inhibited the anticancer effects of the plasma, similar to the effect of caspase inhibitor z-VAD or ROS scavenger N-acetyl cysteine. These results confirm the role of TP73 protein in dose-dependent regulation of anticancer activity of atmospheric-pressure plasmas.

  5. Intracellular effects of atmospheric-pressure plasmas on melanoma cancer cells

    NASA Astrophysics Data System (ADS)

    Ishaq, M.; Bazaka, K.; Ostrikov, K.

    2015-12-01

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown as a promising tool for cancer treatment. The mechanism of the plasma action is attributed to generation of reactive oxygen and nitrogen species, electric fields, charges, and photons. The relative importance of different modes of action of atmospheric-pressure plasmas depends on the process parameters and specific treatment objects. Hence, an in-depth understanding of biological mechanisms that underpin plasma-induced death in cancer cells is required to optimise plasma processing conditions. Here, the intracellular factors involved in the observed anti-cancer activity in melanoma Mel007 cells are studied, focusing on the effect of the plasma treatment dose on the expression of tumour suppressor protein TP73. Over-expression of TP73 causes cell growth arrest and/or apoptosis, and hence can potentially be targeted to enhance killing efficacy and selectivity of the plasma treatment. It is shown that the plasma treatment induces dose-dependent up-regulation of TP73 gene expression, resulting in significantly elevated levels of TP73 RNA and protein in plasma-treated melanoma cells. Silencing of TP73 expression by means of RNA interference inhibited the anticancer effects of the plasma, similar to the effect of caspase inhibitor z-VAD or ROS scavenger N-acetyl cysteine. These results confirm the role of TP73 protein in dose-dependent regulation of anticancer activity of atmospheric-pressure plasmas.

  6. 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.

  7. Application of Langmuir Probe Method to the Atmospheric Pressure Discharge Plasma

    SciTech Connect

    Matsuura, Hiroto; Matsumura, Yasuhiro; Nakano, Ken

    2008-12-31

    The heat balance model in the probe tip applied to atmospheric pressure plasma is constructed. Considering the natural convective heat loss, the limitation of plasma density for probe application to such a plasma is estimated. The rough limit is about n{sub e} = 10{sup 18} m{sup -3}. Four kind of materials (Cu, SUS, W, Al) are used for probe tips, and are tested in DC atmospheric pressure discharge. Heat conductivity is found to be a more important property than melting point in design of probes in high pressure discharge. DC atmospheric pressure discharge plasma parameters are obtained with our test probes. Obtained density is the order of 10{sup 17} m{sup -3} and does not contradict with the above density limitation. Change of space potential in air/Ar plasma is also confirmed.

  8. 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

  9. Synthesis of magnetic nanoparticles by atmospheric-pressure plasma electrolysis and observation of liquid flow induced by plasma

    NASA Astrophysics Data System (ADS)

    Shirai, Naoki; Yoshida, Taketo; Aoki, Takuya; Uchida, Satoshi; Tochikubo, Fumiyoshi

    2015-09-01

    For the synthesis of magnetic metal NPs (nanoparticles), we used the electrolysis combined with atmospheric-pressure plasma. Plasma irradiated positive ions or electron to the solution surface; it worked as electrode of electrolysis. In the case of using aqueous solutions of FeCl2, magnetic NPs were synthesized at plasma-liquid interface when electron was irradiated to liquid surface. The plasma was generated in a miniature helium gas flow surrounded by a shielding gas flow controlling the gas condition around the plasma. The condition of magnetic NPs synthesis depended on the shielding gas species of plasma. In the case of using Ar or N2 shielding gas, magnetic NPs were synthesized. On the other hand, in the case of using O2 shielding gas or without shielding gas, magnetic NPs were not synthesized. To synthesize NPs without chemicals such as FeCl2 solutions, we use plasma electrolysis with iron electrode which is immersed in liquid. When plasma electrolysis was operated, iron electrode eluted to Fe cation and it becomes magnetic NPs at plasma-liquid interface. By using this method much of Fe3O4 is synthesized. In addition, we investigated liquid flow of plasma electrolysis by using Schlieren visualization. Liquid flow was observed when plasma electrolysis was operated.

  10. Surface chemical changes of atmospheric pressure plasma treated rabbit fibres important for felting process

    NASA Astrophysics Data System (ADS)

    Štěpánová, Vlasta; Slavíček, Pavel; Stupavská, Monika; Jurmanová, Jana; Černák, Mirko

    2015-11-01

    We introduce the atmospheric pressure plasma treatment as a suitable procedure for in-line industrial application of rabbit fibres pre-treatment. Changes of rabbit fibre properties due to the plasma treatment were studied in order to develop new technology of plasma-based treatment before felting. Diffuse Coplanar Surface Barrier Discharge (DCSBD) in ambient air at atmospheric pressure was used for plasma treatment. Scanning electron microscopy was used for determination of the fibres morphology before and after plasma treatment. X-ray photoelectron spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy were used for evaluation of reactive groups. The concentration of carbon decreased and conversely the concentration of nitrogen and oxygen increased after plasma treatment. Aging effect of plasma treated fibres was also investigated. Using Washburn method the significant increase of fibres wettability was observed after plasma treatment. New approach of pre-treatment of fibres before felting using plasma was developed. Plasma treatment of fibres at atmospheric pressure can replace the chemical method which consists of application of strong acids on fibres.