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Sample records for plasma assisted measurements

  1. Thrust Stand Measurements of the Microwave Assisted Discharge Inductive Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley K.; Polzin, Kurt A.; Emsellem, Gregory D.

    2011-01-01

    Pulsed inductive plasma thrusters [1-3] are spacecraft propulsion devices in which electrical energy is capacitively stored and then discharged through an inductive coil. This type of pulsed thruster is electrodeless, with a time-varying current in the coil interacting with a plasma covering the face of the coil to induce a plasma current. Propellant is accelerated and expelled at a high exhaust velocity (O(10-100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, pulsed inductive plasma thrusters require high pulse energies to inductively ionize propellant. The Microwave Assisted Dis- charge Inductive Plasma Accelerator (MAD-IPA), shown in Fig. 1, is a pulsed inductive plasma thruster that addressees this issue by partially ionizing propellant inside a conical inductive coil before the main current pulse via an electron cyclotron resonance (ECR) discharge. The ECR plasma is produced using microwaves and a static magnetic field from a set of permanent magnets arranged to create a thin resonance region along the inner surface of the coil, restricting plasma formation, and in turn current sheet formation, to a region where the magnetic coupling between the plasma and the theta-pinch coil is high. The use of a conical theta-pinch coil also serves to provide neutral propellant containment and plasma plume focusing that is improved relative to the more common planar geometry of the Pulsed Inductive Thruster (PIT) [1, 2]. In this paper, we describe thrust stand measurements performed to characterize the performance (specific impulse, thrust efficiency) of the MAD-IPA thruster. Impulse data are obtained at various pulse energies, mass flow rates and inductive coil geometries. Dependencies on these experimental parameters are discussed in the context of the current sheet formation and electromagnetic plasma

  2. Thrust Stand Measurements Using Alternative Propellants in the Microwave Assisted Discharge Inductive Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley K.; Polzin, Kurt A.

    2011-01-01

    Storable propellants (for example water, ammonia, and hydrazine) are attractive for deep space propulsion due to their naturally high density at ambient interplanetary conditions, which obviates the need for a cryogenic/venting system. Water in particular is attractive due to its ease of handling and availability both terrestrially and extra-terrestrially. While many storable propellants are reactive and corrosive, a propulsion scheme where the propellant is insulated from vulnerable (e.g. metallic) sections of the assembly would be well-suited to process these otherwise incompatible propellants. Pulsed inductive plasma thrusters meet this criterion because they can be operated without direct propellant-electrode interaction. During operation of these devices, electrical energy is capacitively stored and then discharged through an inductive coil creating a time-varying current in the coil that interacts with a plasma covering the face of the coil to induce a plasma current. Propellant is accelerated and expelled at a high exhaust velocity (O(10-100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, many pulsed inductive plasma thrusters require high pulse energies to inductively ionize propellant. The Microwave Assisted Discharge Inductive Plasma Accelerator (MAD-IPA) is a pulsed inductive plasma thruster that addressees this issue by partially ionizing propellant inside a conical inductive coil before the main current pulse via an electron cyclotron resonance (ECR) discharge. The ECR plasma is produced using microwaves and a static magnetic field from a set of permanent magnets arranged to create a thin resonance region along the inner surface of the coil, restricting plasma formation, and in turn current sheet formation, to a region where the magnetic coupling between the plasma and the theta

  3. A computationally assisted spectroscopic technique to measure secondary electron emission coefficients in technological rf plasmas

    NASA Astrophysics Data System (ADS)

    Berger, Birk; Schulze, Julian; Daksha, Manaswi; Schuengel, Edmund; Koepke, Mark; Korolov, Ihor; Derzsi, Aranka; Donko, Zoltan

    2016-09-01

    A Computationally Assisted Spectroscopic Technique to measure secondary electron emission coefficients (y-CAST) in capacitive rf plasmas is proposed. This non-intrusive, sensitive diagnostic is based on a combination of Phase Resolved Optical Emission Spectroscopy and PIC simulations. Under most conditions in electropositive plasmas the spatio-temporally resolved electron-impact excitation rate features two distinct maxima adjacent to each electrode at different times within one rf period. One maximum is the consequence of an energy gain of the electrons due to sheath expansion. The second maximum is produced by electrons accelerated towards the plasma bulk by the sheath electric field at the time of maximum voltage drop across the sheath. Due to the different excitation mechanisms the ratio of the intensities of these maxima is very sensitive to y, which allows for its determination via comparing the experimentally measured excitation profiles with corresponding simulation data obtained with various y-coefficients. This diagnostic is tested here in a geometrically symmetric reactor, for stainless steel electrodes and argon gas. An effective secondary electron emission coefficient of y = 0.067+-0.010 is obtained, which is in excellent agreement with previous experimental results.

  4. A computationally assisted spectroscopic technique to measure secondary electron emission coefficients in radio frequency plasmas

    NASA Astrophysics Data System (ADS)

    Daksha, M.; Berger, B.; Schuengel, E.; Korolov, I.; Derzsi, A.; Koepke, M.; Donkó, Z.; Schulze, J.

    2016-06-01

    A computationally assisted spectroscopic technique to measure secondary electron emission coefficients (γ-CAST) in capacitively-coupled radio-frequency plasmas is proposed. This non-intrusive, sensitive diagnostic is based on a combination of phase resolved optical emission spectroscopy and particle-based kinetic simulations. In such plasmas (under most conditions in electropositive gases) the spatio-temporally resolved electron-impact excitation/ionization rate features two distinct maxima adjacent to each electrode at different times within each RF period. While one maximum is the consequence of the energy gain of electrons due to sheath expansion, the second maximum is produced by secondary electrons accelerated towards the plasma bulk by the sheath electric field at the time of maximum voltage drop across the adjacent sheath. Due to these different excitation/ionization mechanisms, the ratio of the intensities of these maxima is very sensitive to the secondary electron emission coefficient γ. This sensitvity, in turn, allows γ to be determined by comparing experimental excitation profiles and simulation data obtained with various γ-coefficients. The diagnostic, tested here in a geometrically symmetric argon discharge, yields an effective secondary electron emission coefficient of γ =0.066+/- 0.01 for stainless steel electrodes.

  5. An improved model to analyze Langmuir probe assisted photo-detachment signal for measuring electronegative plasma parameters

    NASA Astrophysics Data System (ADS)

    Sirse, Nishant; Oudini, Noureddine; Bendib, Abderrezeg; Ellingboe, Albert R.

    2016-09-01

    A diagnostic technique for measuring negative ion parameters based on Langmuir probe assisted laser photo-detachment relies on a theoretical model which relates the rise in the electron saturation current to electronegativity in the plasma. The existing model depend on various assumptions and neglect electrostatic potential barrier formed between the laser column (electropositive column) and the surrounding electronegative plasma in order to prevent the outward flow of electrons from the electropositive plasma column. These assumptions leads to erroneous estimation of the plasma electronegativity. In the present work, we present an analytical model to analyze Langmuir probe assisted photo-detachment signal in order to improve the accuracy of measured electronegativity and extended this technique for measuring electron temperature and charged species density. The analytical model is validated using both experiments and particle-in-cell simulation. The results shows improved accuracy in the measured parameters when compared to existing model. This work was supported by the Korea Institute for the Advancement of Technology and Ministry of Knowledge Economy (L-2010-1438-000), Republic of Korea, Enterprise Ireland and the European Regional Development Fund (ERDF) under NSRF 2007-2013.

  6. Plasma Assisted Combustion

    DTIC Science & Technology

    2007-02-28

    enough formyl radical is accumulated. Inasmuch as formyl oxidizes more intensively than CO, it accumulates on the later stage. At that, processes...plasma has a high mean energy of electrons and will provide a source of reactive atoms, radicals , and excited molecules which has been shown to enhance...3.4.2 Positive ions kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . 129 3.4.3 Production of radicals by electron impact

  7. In-Plasma Photo-Assisted Etching

    NASA Astrophysics Data System (ADS)

    Economou, Demetre

    2015-09-01

    A methodology to precisely control the ion energy distribution (IED) on a substrate allowed the study of silicon etching as a function of ion energy at near-threshold energies. Surprisingly, a substantial etching rate was observed, independent of ion energy, when the ion energy was below the ion-assisted etching threshold (~ 16 eV for etching silicon with chlorine plasma). Careful experiments led to the conclusion that this ``sub-threshold'' etching was due to photons, predominately at wavelengths <1700 Å. Among the plasmas investigated, photo-assisted etching (PAE) was lowest in Br2/Ar gas mixtures and highest in HBr/Cl2/Ar. Above threshold etching rates scaled with the square root of ion energy. PAE rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 Å). Scanning electron and atomic force microscopy (SEM and AFM) revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. In-plasma PAE may be be a complicating factor for processes that require low ion energies, such as atomic layer etching. On the other hand PAE could produce sub-10 nm high aspect ratio (6:1) features by highly selective plasma etching to transfer nascent nanopatterns in silicon. Work supported by DOE Plasma Science Center and NSF.

  8. Electrostatic quadrupole plasma mass spectrometer measurements during thin film depositions using simultaneous matrix assisted pulsed laser evaporation and magnetron sputtering

    SciTech Connect

    Hunter, C. N.; Check, M. H.; Muratore, C.; Voevodin, A. A.

    2010-05-15

    A hybrid plasma deposition process, combining matrix assisted pulsed laser evaporation (MAPLE) of carbon nanopearls (CNPs) with magnetron sputtering of gold was investigated for growth of composite films, where 100 nm sized CNPs were encapsulated into a gold matrix. Composition and morphology of such composite films was characterized with x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy (TEM) analysis. Carbon deposits on a gold magnetron sputter target and carbon impurities in the gold matrices of deposited films were observed while codepositing from gold and frozen toluene-CNP MAPLE targets in pure argon. Electrostatic quadrupole plasma analysis was used to determine that a likely mechanism for generation of carbon impurities was a reaction between toluene vapor generated from the MAPLE target and the argon plasma originating from the magnetron sputtering process. Carbon impurities of codeposited films were significantly reduced by introducing argon-oxygen mixtures into the deposition chamber; reactive oxygen species such as O and O+ effectively removed carbon contamination of gold matrix during the codeposition processes. Increasing the oxygen to argon ratio decreased the magnetron target sputter rate, and hence hybrid process optimization to prevent gold matrix contamination and maintain a high sputter yield is needed. High resolution TEM with energy dispersive spectrometry elemental mapping was used to study carbon distribution throughout the gold matrix as well as embedded CNP clusters. This research has demonstrated that a hybrid MAPLE and magnetron sputtering codeposition process is a viable means for synthesis of composite thin films from premanufactured nanoscale constituents, and that cross-process contaminations can be overcome with understanding of hybrid plasma process interaction mechanisms.

  9. A novel cupping-assisted plasma treatment for skin disinfection

    NASA Astrophysics Data System (ADS)

    Xiong, Zilan; Graves, David B.

    2017-02-01

    A novel plasma treatment method/plasma source called cupping-assisted plasma treatment/source for skin disinfection is introduced. The idea combines ancient Chinese ‘cupping’ technology with plasma sources to generate active plasma inside an isolated, pressure-controlled chamber attached to the skin. Advantages of lower pressure include reducing the threshold voltage for plasma ignition and improving the spatial uniformity of the plasma treatment. In addition, with reduced pressure inside the cup, skin pore permeability might be increased and it improves attachment of the plasma device to the skin. Moreover, at a given pressure, plasma-generated active species are restricted inside the cup, raising local reactive species concentration and enhancing the measured surface disinfection rate. A surface micro-discharge (SMD) device is used as an example of a working plasma source. We report discharge characteristics and disinfection efficiency as a function of pressure and applied voltage.

  10. Non-equilibrium Plasma-Assisted Combustion

    NASA Astrophysics Data System (ADS)

    Sun, Wenting

    As a promising method to enhance combustion, plasma-assisted combustion has drawn considerable attention. Due to the fast electron impact excitation and dissociation of molecules at low temperatures, plasma introduces new reaction pathways, changes fuel oxidation timescales, and can dramatically modify the combustion processes. In this dissertation, the radical generation from the plasma and its effect on flame extinction and ignition were investigated experimentally together with detailed numerical simulation on a counterflow CH4 diffusion flame. It was found that the atomic oxygen production played a dominant role in enhancing the chain-branching reaction pathways and accelerating fuel oxidation at near limit flame conditions. To understand the direct coupling effect between plasma and flame, a novel plasma-assisted combustion system with in situ discharge in a counterflow diffusion flame was developed. The ignition and extinction characteristics of CH4/O 2/He diffusion flames were investigated. For the first time, it was demonstrated that the strong plasma-flame coupling in in situ discharge could significantly modify the ignition/extinction characteristics and create a new fully stretched ignition S-curve. To understand low temperature kinetics of combustion, it is critical to measure the formation and decomposition of H2O2. A molecular beam mass spectrometry (MBMS) system was developed and integrated with a laminar flow reactor. H2O2 measurements were directly calibrated, and compared to kinetic models. The results confirmed that low and intermediate temperature DME oxidation produced significant amounts of H2O2. The experimental characterizations of important intermediate species including H2O2, CH2O and CH3OCHO provided new capabilities to investigate and improve the chemical kinetics especially at low temperatures. A numerical scheme for model reduction was developed to improve the computational efficiency in the simulation of combustion with detailed

  11. Laser diagnostics of plasma assisted combustion

    NASA Astrophysics Data System (ADS)

    Rao, Xing

    In this study, a microwave re-entrant cavity discharge system and a direct current (DC) plasmatron are used to investigate flame enhancement and nitric oxide (NO) formation using laser and optical diagnostics. The uniqueness of this study lies in the direct coupling concept, a novel highly efficient strategy used here for the first time. To investigate combustion dynamics of direct microwave coupled combustion, an atmospheric high-Q re-entrant cavity applicator is used to couple microwave (2.45 GHz) electromagnetic energy directly into the reaction zone of a premixed laminar methane-oxygen flame using a compact torch. When microwave energy increases, a transition from electric field enhancement to microwave plasma discharge is observed. At 6 to 10 Watts, ionization and eventually break-down occurs. 2-D laser induced fluorescence (LIF) imaging of hydroxyl radicals (OH) and carbon monoxide (CO) is conducted in the reaction zone over this transition, as well as spectrally resolved flame emission measurements. These measurements serve to monitor excited state species and derive rotational temperatures using OH chemiluminescence for a range of equivalence ratios (both rich and lean) and total flow rates. Combustion dynamics is also investigated for plasma enhanced methane-air flames in premixed and nonpremixed configurations using a transient arc DC plasmatron. Results for OH and CO PLIF also indicate the differences in stability mechanism, and energy consumption for premixed and nonpremixed modes. It is shown that both configurations are significantly influenced by in-situ fuel reforming at higher plasma powers. Parametric studies are conducted in a plasma assisted methane/air premixed flame for quantitative NO production using a DC plasmatron with PLIF imaging. Quantitative measurements of NO are reported as a function of gas flow rate (20 to 50 SCFH), plasma power (100 to 900 mA, 150 to 750 W) and equivalence ratio (0.7 to 1.3). NO PLIF images and single point NO

  12. TOPICAL REVIEW: Plasma assisted ignition and combustion

    NASA Astrophysics Data System (ADS)

    Starikovskaia, S. M.

    2006-08-01

    In recent decades particular interest in applications of nonequilibrium plasma for the problems of plasma-assisted ignition and plasma-assisted combustion has been observed. A great amount of experimental data has been accumulated during this period which provided the grounds for using low temperature plasma of nonequilibrium gas discharges for a number of applications at conditions of high speed flows and also at conditions similar to automotive engines. The paper is aimed at reviewing the data obtained and discusses their treatment. Basic possibilities of low temperature plasma to ignite gas mixtures are evaluated and historical references highlighting pioneering works in the area are presented. The first part of the review discusses plasmas applied to plasma-assisted ignition and combustion. The paper pays special attention to experimental and theoretical analysis of some plasma parameters, such as reduced electric field, electron density and energy branching for different gas discharges. Streamers, pulsed nanosecond discharges, dielectric barrier discharges, radio frequency discharges and atmospheric pressure glow discharges are considered. The second part depicts applications of discharges to reduce the ignition delay time of combustible mixtures, to ignite transonic and supersonic flows, to intensify ignition and to sustain combustion of lean mixtures. The results obtained by different authors are cited, and ways of numerical modelling are discussed. Finally, the paper draws some conclusions on the main achievements and prospects of future investigations in the field.

  13. Laser Assisted Plasma Arc Welding

    SciTech Connect

    FUERSCHBACH,PHILLIP W.

    1999-10-05

    Experiments have been performed using a coaxial end-effecter to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (< 1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

  14. Plasma-assisted microwave processing of materials

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin (Inventor); Ylin, Tzu-yuan (Inventor); Jackson, Henry (Inventor)

    1998-01-01

    A microwave plasma assisted method and system for heating and joining materials. The invention uses a microwave induced plasma to controllably preheat workpiece materials that are poorly microwave absorbing. The plasma preheats the workpiece to a temperature that improves the materials' ability to absorb microwave energy. The plasma is extinguished and microwave energy is able to volumetrically heat the workpiece. Localized heating of good microwave absorbing materials is done by shielding certain parts of the workpiece and igniting the plasma in the areas not shielded. Microwave induced plasma is also used to induce self-propagating high temperature synthesis (SHS) process for the joining of materials. Preferably, a microwave induced plasma preheats the material and then microwave energy ignites the center of the material, thereby causing a high temperature spherical wave front from the center outward.

  15. Modelling the plasma plume of an assist source in PIAD

    NASA Astrophysics Data System (ADS)

    Wauer, Jochen; Harhausen, Jens; Foest, Rüdiger; Loffhagen, Detlef

    2016-09-01

    Plasma ion assisted deposition (PIAD) is a technique commonly used to produce high-precision optical interference coatings. Knowledge regarding plasma properties is most often limited to dedicated scenarios without film deposition. Approaches have been made to gather information on the process plasma in situ to detect drifts which are suspected to cause limits in repeatability of resulting layer properties. Present efforts focus on radiance monitoring of the plasma plume of an Advanced Plasma Source (APSpro, Bühler) by optical emission spectroscopy to provide the basis for an advanced plasma control. In this contribution modelling results of the plume region are presented to interpret these experimental data. In the framework of the collisional radiative model used, 15 excited neutral argon states in the plasma are considered. Results of the species densities show good consistency with the measured optical emission of various argon 2 p - 1 s transitions. This work was funded by BMBF under grant 13N13213.

  16. Plasma Assisted ISRU at Mars

    NASA Technical Reports Server (NTRS)

    Moses, Robert W.; Kuhl, Christopher A.; Templeton, Justin D.

    2005-01-01

    NASA's exploration goals for Mars and Beyond will require new power systems and in situ resource utilization (ISRU) technologies. Regenerative aerobraking may offer a revolutionary approach for in situ power generation and oxygen harvesting during these exploration missions. In theory, power and oxygen can be collected during aerobraking and stored for later use in orbit or on the planet. This technology would capture energy and oxygen from the plasma field that occurs naturally during hypersonic entry using well understood principles of magnetohydrodynamics and oxygen filtration. This innovative approach generates resources upon arrival at the operational site, and thus greatly differs from the traditional approach of taking everything you need with you from Earth. Fundamental analysis, computational fluid dynamics, and some testing of experimental hardware have established the basic feasibility of generating power during a Mars entry. Oxygen filtration at conditions consistent with spacecraft entry parameters at Mars has been studied to a lesser extent. Other uses of the MHD power are presented. This paper illustrates how some features of regenerative aerobraking may be applied to support human and robotic missions at Mars.

  17. Plasma assisted deposition of metal fluorides for 193nm applications

    NASA Astrophysics Data System (ADS)

    Bischoff, Martin; Sode, Maik; Gaebler, Dieter; Kaiser, Norbert; Tuennermann, Andreas

    2008-10-01

    The ArF lithography technology requires a minimization of optical losses due to scattering and absorption. Consequently it is necessary to optimize the coating process of metal fluorides. The properties of metal fluoride thin films are mainly affected by the deposition methods, their parameters, and the vacuum conditions. Until now the best results were achieved by metal boat evaporation with high substrate temperature and without plasma assistance. In fact, it was demonstrated that the plasma assisted deposition process results in optical thin films with high packing density but the losses due to absorption were extremely high for deep and vacuum ultraviolet applications. This paper will demonstrate that most of the common metal fluorides can be deposited by electron beam evaporation with plasma assistance. In comparison to other deposition methods, the prepared thin films show low absorption in the VUV spectral range, high packing density, and less water content. The densification of the thin films was performed by a Leybold LION plasma source. As working gas, a variable mixture of fluorine and argon gas was chosen. To understand the deposition process and the interaction of the plasma with the deposition material, various characterization methods like plasma emission spectroscopy and ion current measurements were implemented.

  18. Separation and measurement of Pa, Th, and U isotopes in marine sediments by microwave-assisted digestion and multiple collector inductively coupled plasma mass spectrometry.

    PubMed

    Negre, César; Thomas, Alexander L; Mas, José Luis; Garcia-Orellana, Jordi; Henderson, Gideon M; Masqué, Pere; Zahn, Rainer

    2009-03-01

    This manuscript describes a new protocol for determination of Pa/Th/U in marine sediments. It is based on microwave-assisted digestion and represents an important reduction of working time over conventional hot-plate digestion methods, and the use of HClO(4) is avoided. Although Th and U are completely dissolved with a first microwave step, around 40% of (231)Pa remains undissolved, and a short hot-plate step with reverse aqua regia is required to achieve total digestion and spike equilibration. Next, the method involves a separation of these elements and a further purification of the Pa fraction using Dowex AG1-X8 resin. Separation with Bio-Rad and Sigma-Aldrich resins was compared; although both perform similarly for Th and U, Pa yields are higher with Bio-Rad. Finally, samples are measured using a Nu instruments multiple collector inductively coupled plasma mass spectrometer (MC-ICPMS). Overall chemical yields range around 50% for Pa, 60% for Th, and 70% for U.

  19. Bandgap measurements and the peculiar splitting of E2H phonon modes of InxAl1-xN nanowires grown by plasma assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Tangi, Malleswararao; Mishra, Pawan; Janjua, Bilal; Ng, Tien Khee; Anjum, Dalaver H.; Prabaswara, Aditya; Yang, Yang; Albadri, Abdulrahman M.; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ooi, Boon S.

    2016-07-01

    The dislocation free InxAl1-xN nanowires (NWs) are grown on Si(111) by nitrogen plasma assisted molecular beam epitaxy in the temperature regime of 490 °C-610 °C yielding In composition ranges over 0.50 ≤ x ≤ 0.17. We study the optical properties of these NWs by spectroscopic ellipsometry (SE), photoluminescence, and Raman spectroscopies since they possesses minimal strain with reduced defects comparative to the planar films. The optical bandgap measurements of InxAl1-xN NWs are demonstrated by SE where the absorption edges of the NW samples are evaluated irrespective of substrate transparency. A systematic Stoke shift of 0.04-0.27 eV with increasing x was observed when comparing the micro-photoluminescence spectra with the Tauc plot derived from SE. The micro-Raman spectra in the NWs with x = 0.5 showed two-mode behavior for A1(LO) phonons and single mode behavior for E2H phonons. As for x = 0.17, i.e., high Al content, we observed a peculiar E2H phonon mode splitting. Further, we observe composition dependent frequency shifts. The 77 to 600 K micro-Raman spectroscopy measurements show that both AlN- and InN-like modes of A1(LO) and E2H phonons in InxAl1-xN NWs are redshifted with increasing temperature, similar to that of the binary III group nitride semiconductors. These studies of the optical properties of the technologically important InxAl1-xN nanowires will path the way towards lasers and light-emitting diodes in the wavelength of the ultra-violet and visible range.

  20. Plasma assisted synthesis of vanadium pentoxide nanoplates

    NASA Astrophysics Data System (ADS)

    Singh, Megha; Sharma, Rabindar Kumar; Kumar, Prabhat; Reddy, G. B.

    2015-08-01

    In this work, we report the growth of α-V2O5 (orthorhombic) nanoplates on glass substrate using plasma assisted sublimation process (PASP) and Nickel as catalyst. 100 nm thick film of Ni is deposited over glass substrate by thermal evaporation process. Vanadium oxide nanoplates have been deposited treating vanadium metal foil under high vacuum conditions with oxygen plasma. Vanadium foil is kept at fixed temperature growth of nanoplates of V2O5 to take place. Samples grown have been studied using XPS, XRD and HRTEM to confirm the growth of α-phase of V2O5, which revealed pure single crystal of α- V2O5 in orthorhombic crystallographic plane. Surface morphological studies using SEM and TEM show nanostructured thin film in form of plates. Uniform, vertically aligned randomly oriented nanoplates of V2O5 have been deposited.

  1. Raman spectroscopy based measurements of carrier concentration in n-type GaN nanowires grown by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Robins, L. H.; Horneber, E.; Sanford, N. A.; Bertness, K. A.; Brubaker, M. D.; Schlager, J. B.

    2016-09-01

    The carrier concentration in as-grown ensembles of n-type GaN nanowires was determined by Raman spectroscopy of the coupled longitudinal phonon-plasmon (LPP+) mode and modeling of the carrier concentration dependence of the LPP+ frequency. The Raman measurements and analyses enabled estimation of the carrier concentration in single-nanowire devices fabricated from the as-grown ensembles. The nanowires were grown by plasma-assisted molecular beam epitaxy in either of the two growth systems. Twelve samples were examined, of which 11 samples were Si-doped and one was undoped. The Raman-measured carrier concentrations in the Si-doped samples ranged from (5.28 ± 1.19) × 1016 cm-3 to (6.16 ± 0.35) × 1017 cm-3. For a subset of samples grown with varying Si cell temperature, from 1125 °C to 1175 °C, the carrier concentration was found to be an Arrhenius function of Si cell temperature, with activation energy of 6.281 ± 0.011 eV . Co-illumination by an above band gap UV laser (325 nm, excitation intensity = 0.7 W/cm2 or 4.5 W/cm2) induced small increases in carrier concentration, relative to illumination by the Raman excitation laser alone (633 nm, excitation intensity ≈100 kW/cm2). The lowest Si-doped sample showed the largest increase in carrier concentration, (6.3 ± 4.8) × 1015 cm-3 with UV excitation intensity of 0.7 W/cm2. These results imply that, even in the absence of UV illumination, surface depletion does not have a significant effect on the Raman carrier concentration measurements. Immersion in a high-dielectric-constant oil (ɛ = 2.24) caused downshifts of similar magnitude in the LPP+ frequencies of undoped and doped nanowires. This result implies that the LPP+ mode has bulk plasmon rather than surface plasmon character, because immersion in a high-dielectric-constant medium is predicted to cause a large decrease in the surface plasmon frequency, which would induce a larger LPP+ downshift in doped than undoped nanowires. A surface optical (SO) phonon

  2. New Combustion Regimes and Kinetic Studies of Plasma Assisted Combustion

    DTIC Science & Technology

    2012-11-01

    New combustion regimes and kinetic studies of plasma assisted combustion Nov.6-7, 2012 MURI Plasma 3rd Yr Review Meeting MURI Topic #11: Chemical...TITLE AND SUBTITLE New combustion regimes and kinetic studies of plasma assisted combustion 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...Flow reactor Species and kinetics (Ju) 1. New combustion regimes and kinetic studies of in situ plasma discharge in counterflow flames

  3. Plasma-Assisted Combustion Studies at AFRL

    DTIC Science & Technology

    2009-11-04

    Areas where plasmas and E-fields can have an influence • Enhance reaction rate & flamespeed  Important for high -speed combustors (& other combustors...pulse frequency  XH2O measured with TDLAS • PLIF of OH: Peak signals ~1015 cm-3 12 anode Ignition Enhancement with TP* *Singleton, Pendleton...Gundersen (USC), Stockman, Carter, Brown • Camera looking down into chamber • Continuous flow of moist air  1-Hz pulse frequency  XH2O measured with TDLAS

  4. Plasma assisted synthesis of vanadium pentoxide nanoplates

    SciTech Connect

    Singh, Megha; Sharma, Rabindar Kumar; Kumar, Prabhat Reddy, G. B.

    2015-08-28

    In this work, we report the growth of α-V{sub 2}O{sub 5} (orthorhombic) nanoplates on glass substrate using plasma assisted sublimation process (PASP) and Nickel as catalyst. 100 nm thick film of Ni is deposited over glass substrate by thermal evaporation process. Vanadium oxide nanoplates have been deposited treating vanadium metal foil under high vacuum conditions with oxygen plasma. Vanadium foil is kept at fixed temperature growth of nanoplates of V{sub 2}O{sub 5} to take place. Samples grown have been studied using XPS, XRD and HRTEM to confirm the growth of α-phase of V{sub 2}O{sub 5}, which revealed pure single crystal of α- V{sub 2}O{sub 5} in orthorhombic crystallographic plane. Surface morphological studies using SEM and TEM show nanostructured thin film in form of plates. Uniform, vertically aligned randomly oriented nanoplates of V{sub 2}O{sub 5} have been deposited.

  5. Fundamental Mechanisms, Predictive Modeling, and Novel Aerospace Applications of Plasma Assisted Combustion

    DTIC Science & Technology

    2009-11-04

    intrusive diagnostics • Task 2: Laminar Flow Reactor and Nanoparticle Studies at Low to Intermediate Temperatures (Radar REMPI and Filtered Rayleigh...using counterflow flames Thrust 2. Intermediate Species Measurements at Elevated Pressures by Using a Plasma Assisted Jet Stirred Reactor with...Molecular Beam Sampling – Task 1: Development of plasma assisted a jet stirred reactor Task 2: Measurements of intermediate species of fuel oxidation

  6. Plasma Assisted Combustion: Flame Regimes and Kinetic Studies

    DTIC Science & Technology

    2015-01-05

    Plasma Assisted Combustion: Flame Regimes and Kinetic Studies Yiguang Ju, Joseph Lefkowitz, Tomoya Wada, and Sanghee Won Department of Mechanical...DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE Plasma Assisted Combustion: Flame Regimes and Kinetic Studies 5a. CONTRACT NUMBER...Tube (Starikovskiy) RCM (Starikovskiy) MW+laser (Miles) JSR/Flow reactor Species and kinetics (Ju) 1. Plasma activated low temperature

  7. Lower hybrid assisted plasma current ramp-up in ITER

    NASA Astrophysics Data System (ADS)

    Kim, S. H.; Artaud, J. F.; Basiuk, V.; Bécoulet, A.; Dokuka, V.; Hoang, G. T.; Imbeaux, F.; Khayrutdinov, R. R.; Lister, J. B.; Lukash, V. E.

    2009-06-01

    Lower hybrid (LH) assisted plasma current ramp-up in ITER is demonstrated using a free-boundary full tokamak discharge simulator which combines the DINA-CH and CRONOS codes. LH applied from the initial phase of the plasma current ramp-up increases the safety margins in operating the superconducting poloidal field coils both by reducing resistive ohmic flux consumption and by providing non-inductively driven plasma current. Loss of vertical control associated with high plasma internal inductance is avoided by tailoring the plasma current density profiles. Effects of early LH application on the plasma shape evolution are identified by the free-boundary plasma simulation.

  8. Investigation of sewage sludge treatment using air plasma assisted gasification.

    PubMed

    Striūgas, Nerijus; Valinčius, Vitas; Pedišius, Nerijus; Poškas, Robertas; Zakarauskas, Kęstutis

    2017-03-18

    This study presents an experimental investigation of downdraft gasification process coupled with a secondary thermal plasma reactor in order to perform experimental investigations of sewage sludge gasification, and compare process parameters running the system with and without the secondary thermal plasma reactor. The experimental investigation were performed with non-pelletized mixture of dried sewage sludge and wood pellets. To estimate the process performance, the composition of the producer gas, tars, particle matter, producer gas and char yield were measured at the exit of the gasification and plasma reactor. The research revealed the distribution of selected metals and chlorine in the process products and examined a possible formation of hexachlorobenzene. It determined that the plasma assisted processing of gaseous products changes the composition of the tars and the producer gas, mostly by destruction of hydrocarbon species, such as methane, acetylene, ethane or propane. Plasma processing of the producer gas reduces their calorific value but increases the gas yield and the total produced energy amount. The presented technology demonstrated capability both for applying to reduce the accumulation of the sewage sludge and production of substitute gas for drying of sewage sludge and electrical power.

  9. Plasma Beam Measurements

    DTIC Science & Technology

    1991-08-01

    GUN PLASMA BEAM / ,I 21 cm diameter = 0 GLASS DRIFT TUBE 50 cm diameter MCP CAMERA CLASS CROSSES (a) Gun muzzle /"- PLASA BEAM / TAROT z = 10 m MCP...discusses some of the hydrodynamic issues related to the calcula- tions. The reader may well wonder why hydrodynamics should be an issue in a 116 WL-TR-90...answer is yes for the slow beam cases and no for the fast beam cases. This is explained further. 118 WL-TR-90-83 The reader will recall the

  10. Emission characteristics of kerosene-air spray combustion with plasma assistance

    NASA Astrophysics Data System (ADS)

    Liu, Xingjian; He, Liming; Zeng, Hao; Jin, Tao; Chen, Yi; Zhang, Yihan; Liu, Pengfei

    2015-09-01

    A plasma assisted combustion system for combustion of kerosene-air mixtures was developed to study emission levels of O2, CO2, CO, and NOx. The emission measurement was conducted by Testo 350-Pro Flue Gas Analyzer. The effect of duty ratio, feedstock gas flow rate and applied voltage on emission performance has been analyzed. The results show that O2 and CO emissions reduce with an increase of applied voltage, while CO2 and NOx emissions increase. Besides, when duty ratio or feedstock gas flow rate decreases, the same emission results would appear. The emission spectrum of the air plasma of plasma assisted combustion actuator was also registered to analyze the kinetic enhancement effect of plasma, and the generation of ozone was believed to be the main factor that plasma makes a difference in our experiment. These results are valuable for the future optimization of kerosene-fueled aircraft engine when using plasma assisted combustion devices to exert emission control.

  11. Assessment of ultrasound-assisted extraction as sample pre-treatment for the measurement of lead isotope ratios in marine biological tissues by multicollector inductively coupled plasma-mass spectrometry

    NASA Astrophysics Data System (ADS)

    Costas-Rodríguez, M.; Lavilla, Isela; Bendicho, Carlos

    2011-06-01

    In this work, ultrasound-assisted extraction (UAE) was evaluated as a sample preparation procedure for lead isotope ratio measurements in marine biological tissues by multicollector inductively coupled plasma-mass spectrometry. 20 mg of marine biological tissue and 1 mL of acid extractant were sonicated for 3 min at 60% ultrasound amplitude. Matrix separation was performed in the supernatant using a chromatographic exchange resin (Sr-Spec™). Total elimination of organic matter was achieved during the separation step. Microwave-assisted digestion and dry-ashing were used for comparative purposes. No significant differences were found in lead isotope ratios at 95% of confidence level. UAE emerges as an advantageous alternative to classical methods for sample preparation owing to its simplicity and rapidity ( i.e. operation steps were reduced), low reagent consumption and low contamination risks.

  12. Exhaust aftertreatment using plasma-assisted catalysis

    SciTech Connect

    Penetrante, B

    2000-01-20

    preconverting NO to NO{sub 2} could improve both the efficiency and durability of lean-NO{sub x} catalysts. A non-thermal plasma is an efficient means for selective partial oxidation of NO to NO{sub 2}. The use of a non-thermal plasma in combination with a lean-NO{sub x} catalyst opens the opportunity for catalysts that are more efficient and more durable compared to conventional catalysts. In the absence of hydrocarbons, the O radicals will oxidize NO to NO{sub 2}, and the OH radicals will further oxidize NO{sub 2} to nitric acid. In plasma-assisted catalysis it is important that the plasma oxidize NO to NO{sub 2} without further producing acids.

  13. COLD-PLASMA ASSISTED GRAFTING OF PAPER

    SciTech Connect

    Gaiolas, C.; Costa, A. P.; Nunes, M.; Silva, M. J. Santos; Belgacem, M. N.

    2008-08-28

    The treatment of cellulose with cold-plasma in the presence of two silanes (vinyltrimethoxysilane and {gamma}-methacryloxypropyltrimethoxysilane) was found to be efficient in grafting of cellulose macromolecules. The occurrence of the grafting was proved by contact angle measurement, ESCA and SEM. Thus, after solvent extraction of the modified substrates, in order to remove unbounded grafts, the polar component of the surface energy of treated samples decreased from 23 mJ/m{sup 2} to practically zero. The ESCA spectra showed the appearance of two new peaks at 102 and 150 eV, relative to the presence of Si atoms and a substantial increase in C1 signal, attributed to the enrichment of the surface by C-H moieties borne by the silanes.

  14. Cold-Plasma Assisted Grafting of Paper

    NASA Astrophysics Data System (ADS)

    Gaiolas, C.; Costa, A. P.; Nunes, M.; Silva, M. J. Santos; Belgacem, M. N.

    2008-08-01

    The treatment of cellulose with cold-plasma in the presence of two silanes (vinyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane) was found to be efficient in grafting of cellulose macromolecules. The occurrence of the grafting was proved by contact angle measurement, ESCA and SEM. Thus, after solvent extraction of the modified substrates, in order to remove unbounded grafts, the polar component of the surface energy of treated samples decreased from 23 mJ/m2 to practically zero. The ESCA spectra showed the appearance of two new peaks at 102 and 150 eV, relative to the presence of Si atoms and a substantial increase in C1 signal, attributed to the enrichment of the surface by C-H moieties borne by the silanes.

  15. Plasma-Assisted Synthesis of Carbon Nanotubes

    PubMed Central

    2010-01-01

    The application of plasma-enhanced chemical vapour deposition (PECVD) in the production and modification of carbon nanotubes (CNTs) will be reviewed. The challenges of PECVD methods to grow CNTs include low temperature synthesis, ion bombardment effects and directional growth of CNT within the plasma sheath. New strategies have been developed for low temperature synthesis of single-walled CNTs based the understanding of plasma chemistry and modelling. The modification of CNT surface properties and synthesis of CNT hybrid materials are possible with the utilization of plasma. PMID:20802785

  16. Measuring Assistive Technology Outcomes in Education.

    ERIC Educational Resources Information Center

    Smith, Roger O.

    2000-01-01

    This article reviews relevant theory and the practical implications of measuring assistive technology outcomes of students with disabilities. Rasch Measurement Scaling, Time Series Concurrent and Differential Approach, and the Multi-Attribute Utility Model are proposed for potential use in assistive technology outcome measurement and future…

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  18. Damping Measurements of Plasma Modes

    NASA Astrophysics Data System (ADS)

    Anderegg, F.; Affolter, M.; Driscoll, C. F.

    2010-11-01

    For azimuthally symmetric plasma modes in a magnesium ion plasma, confined in a 3 Tesla Penning-Malmberg trap with a density of n ˜10^7cm-3, we measure a damping rate of 2s-1< γ< 10^4s-1 over a wide range in temperature (5 x10-6 eV< T < 5eV) and aspect ratio (0.25 < α< 25), with a wave amplitude of δn / n ˜5%. Changing the aspect ratio, α= Lp/ 2rp, of the plasma column, alters the frequency of the mode from 16 KHz to 192 KHz. The oscillatory fluid displacement is small compared to the wavelength of the mode; in contrast, the fluid velocity, δvf, can be large compared to v. The real part of the frequency satisfies a linear dispersion relation. In long thin plasmas (α> 10) these modes are Trivelpiece-Gould (TG) modes, and for smaller values of α they are Dubin spheroidal modes. However the damping appears to be non-linear; initially large waves have weaker exponential damping, which is not yet understood. Recent theoryootnotetextM.W. Anderson and T.M. O'Neil, Phys. Plasmas 14, 112110 (2007). calculates the damping of TG modes expected from viscosity due to ion-ion collisions; but the measured damping, while having a similar temperature and density dependence, is about 40 times larger than calculated. This discrepancy might be due to an external damping mechanism.

  19. Plasma Anemometer Measurements and Optimization

    NASA Astrophysics Data System (ADS)

    Marshall, Curtis; Matlis, Eric; Corke, Thomas; Gogineni, Sivaram

    2013-11-01

    Velocity measurements using a constant-current plasma anemometer were performed in a Mach 0.4 jet in order to further optimize the anemometer design. The plasma anemometer uses an AC glow discharge (plasma) formed in the air gap between two protruding low profile electrodes as the flow sensing element. The output from the anemometer is an amplitude modulated version of the AC voltage input that contains information about the mean fluctuating velocity components. Experiments were performed to investigate the effect of the electrode gap, AC current, and AC frequency on the mean and fluctuating velocity sensitivity and repeatability of the sensor. This involved mean velocity calibrations from 0 to 140 m/s and mean and fluctuating velocity profiles through the shear layer of the jet. Measurements with a constant temperature hot-wire anemometer were used for reference. The results showed an improvement in performance with increasing AC frequency that was attributed a more stable glow discharge. The agreement with the hot-wire were good, with the advantage of the plasma anemometer being its 100-times higher frequency response. Supported by Air Force SBIR Phase II FA8650-11-C-2199.

  20. Plasma Assisted Combustion in a Supersonic Flow

    NASA Astrophysics Data System (ADS)

    Do, Hyungrok; Im, Seong-Kyun; Cappelli, Mark; Mungal, Mark

    2009-10-01

    A nanosecond pulsed plasma discharge is used to ignite jet (hydrocarbon and hydrogen) flames in supersonic air cross flows (Ma = 1.7 to 3.0). The flow pattern and shockwaves induced by the fuel jets and flow disturbances are characterized by Schlieren imaging. Planar laser induced fluorescence and emission spectroscopy are employed for imaging the distribution of OH radicals. Two common test model flow configurations (cavity and flat wall) are used with integration electrodes for plasma excitation. Cavity flames are found to be readily enhanced by plasma excitation, with a clear reduction in ignition delay time. However, flame propagation beyond the cavity is limited. A flat wall configuration combining an upstream subsonic oblique fuel jet and a downstream sonic transverse fuel jet is shown to provide a more favorable flow condition for jet flame ignition and propagation. The OH distribution in the vicinity of the discharge confirms jet flame ignition by the plasma. Experimental results are validated using a simple theoretical/numerical model. The reduction in the ignition delay and other qualitative features are validated by the model.

  1. Plasma assisted surface treatments of biomaterials.

    PubMed

    Minati, L; Migliaresi, C; Lunelli, L; Viero, G; Dalla Serra, M; Speranza, G

    2017-10-01

    The biocompatibility of an implant depends upon the material it is composed of, in addition to the prosthetic device's morphology, mechanical and surface properties. Properties as porosity and pore size should allow, when required, cells penetration and proliferation. Stiffness and strength, that depend on the bulk characteristics of the material, should match the mechanical requirements of the prosthetic applications. Surface properties should allow integration in the surrounding tissues by activating proper communication pathways with the surrounding cells. Bulk and surface properties are not interconnected, and for instance a bone prosthesis could possess the necessary stiffness and strength for the application omitting out prerequisite surface properties essential for the osteointegration. In this case, surface treatment is mandatory and can be accomplished using various techniques such as applying coatings to the prosthesis, ion beams, chemical grafting or modification, low temperature plasma, or a combination of the aforementioned. Low temperature plasma-based techniques have gained increasing consensus for the surface modification of biomaterials for being effective and competitive compared to other ways to introduce surface functionalities. In this paper we review plasma processing techniques and describe potentialities and applications of plasma to tailor the interface of biomaterials. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Fundamental Study of a Laser-Assisted Plasma Thruster

    NASA Astrophysics Data System (ADS)

    Horisawa, Hideyuki; Kawakami, Masatoshi; Lin, Wun-Wei; Igari, Akira; Kimura, Itsuro

    2003-05-01

    In this study we propose a novel laser-assisted plasma thruster, in which plasma is induced through a laser beam irradiation onto a target, or a laser-assisted process, and accelerated by electrical means instead of a direct acceleration only by using a laser beam. Inducing the short-duration conductive plasma between electrodes with certain voltage, the short-duration switching or a discharge is achieved, in the laser-assisted thruster. Also, reductions of energy losses to electrodes, electrodes erosion, and an improvement of specific impulse through the intense current caused by the short duration discharge can be expected. Here, a fundamental study of newly developed two-dimensional laser-assisted pulsed-plasma thruster (PPT) and coaxial laser assisted PPT is conducted. A DC power supply (10 ~ 600 V) was used for the power source, and an Nd:YAG laser (wave length: 1.06μm, maximum pulse energy: 1.4J/pulse, pulse width: 10 nsec) was utilized. With this system, the peak current of about 500A with its duration of 3 μsec (FWHM) was observed in a typical case.

  3. Plasma-assisted catalytic storage reduction system

    DOEpatents

    Penetrante, Bernardino M.; Vogtlin, George E.; Merritt, Bernard T.; Brusasco, Raymond M.

    2002-01-01

    A two-stage method for NO.sub.x reduction in an oxygen-rich engine exhaust comprises a plasma oxidative stage and a storage reduction stage. The first stage employs a non-thermal plasma treatment of NO.sub.x gases in an oxygen-rich exhaust and is intended to convert NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons. The second stage employs a lean NO.sub.x trap to convert such NO.sub.2 to environmentally benign gases that include N.sub.2, CO.sub.2, and H.sub.2 O. By preconverting NO to NO.sub.2 in the first stage with a plasma, the efficiency of the second stage for NO.sub.x reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber in which a non-thermal plasma converts NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons, such as propene. A flow of such hydrocarbons (C.sub.x H.sub.y) is input from usually a second pipe into at least a portion of the first chamber. The NO.sub.2 from the plasma treatment proceeds to a storage reduction catalyst (lean NO.sub.x trap) that converts NO.sub.2 to N.sub.2, CO.sub.2, and H.sub.2 O, and includes a nitrate-forming catalytic site. The hydrocarbons and NO.sub.x are simultaneously reduced while passing through the lean-NO.sub.x trap catalyst. The method allows for enhanced NO.sub.x reduction in vehicular engine exhausts, particularly those having relatively high sulfur contents.

  4. Plasma-assisted catalytic storage reduction system

    DOEpatents

    Penetrante, Bernardino M.; Vogtlin, George E.; Merritt, Bernard T.; Brusasco, Raymond M.

    2000-01-01

    A two-stage method for NO.sub.x reduction in an oxygen-rich engine exhaust comprises a plasma oxidative stage and a storage reduction stage. The first stage employs a non-thermal plasma treatment of NO.sub.x gases in an oxygen-rich exhaust and is intended to convert NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons. The second stage employs a lean NO.sub.x trap to convert such NO.sub.2 to environmentally benign gases that include N.sub.2, CO.sub.2, and H.sub.2 O. By preconverting NO to NO.sub.2 in the first stage with a plasma, the efficiency of the second stage for NO.sub.x reduction is enhanced. For example, an internal combustion engine exhaust is connected by a pipe to a first chamber in which a non-thermal plasma converts NO to NO.sub.2 in the presence of O.sub.2 and hydrocarbons, such as propene. A flow of such hydrocarbons (C.sub.x H.sub.y) is input from usually a second pipe into at least a portion of the first chamber. The NO.sub.2 from the plasma treatment proceeds to a storage reduction catalyst (lean NO.sub.x trap) that converts NO.sub.2 to N.sub.2, CO.sub.2, and H.sub.2 O, and includes a nitrate-forming catalytic site. The hydrocarbons and NO.sub.x are simultaneously reduced while passing through the lean-NO.sub.x trap catalyst. The method allows for enhanced NO.sub.x reduction in vehicular engine exhausts, particularly those having relatively high sulfur contents.

  5. Plasma-assisted catalytic ionization using porous nickel plate

    NASA Astrophysics Data System (ADS)

    Oohara, W.; Maeda, T.; Higuchi, T.

    2011-09-01

    Hydrogen atomic pair ions, i.e., H+ and H- ions, are produced by plasma-assisted catalytic ionization using a porous nickel plate. Positive ions in a hydrogen plasma generated by dc arc discharge are irradiated to the porous plate, and pair ions are produced from the back of the irradiation plane. It becomes clear that the production quantity of pair ions mainly depends on the irradiation current of positive ions and the irradiation energy affects the production efficiency of H- ions.

  6. Ferric chloride assisted plasma pretreatment of lignocellulose.

    PubMed

    Ravindran, Rajeev; Sarangapani, Chaitanya; Jaiswal, Swarna; Cullen, P J; Jaiswal, Amit K

    2017-06-26

    In this study, a novel pretreatment for spent coffee waste (SCW) has been proposed which combines two techniques viz. atmospheric air plasma and FeCl3 to create a superior pretreatment that involves Fenton chemistry. The pretreatment was optimised employing Taguchi Design of Experiments, and five parameters were taken into consideration viz. biomass loading, FeCl3 concentration, H2SO4 concentration, plasma discharge voltage and treatment time. The composition analysis of the pretreated SCW revealed substantial amounts of lignin removal, with a maximum for process conditions of 70kV for 2min in an acidic environment containing 1% H2SO4. FTIR, XRD and DSC were performed to characterise the samples. The pretreated SCW after enzymatic hydrolysis yielded 0.496g of reducing sugar/g of SCW. The hydrolysate was subjected to fermentation by S. cerevisiae and led to the production of 18.642g/l of ethanol with a fermentation efficiency of 74%, which was a two fold increase in yield compared to the control. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Plasma Assisted Combustion Mechanism for Small Hydrocarbons

    DTIC Science & Technology

    2015-01-01

    O2 C2H6 C2H4 CH3OH iso‐propane CO2 C3H8 C3H6 C2H5OH neo‐pentane H2O C4H10 CH3OCH3  DME O3 C5H12 Ar H2 N2O PAC  Kinetic  Mechanism  O(-)+N(+)=N+O... Kinetic  Model:  Previous Versions D.V.Zatsepin, S.M.Starikovskaia, A.Yu.Starikovskii Hydrogen oxidation in a  stoichiometric hydrogen‐air mixtures in the... Kinetics  of ignition of saturated hydrocarbons by nonequilibrium plasma: C2H6‐ to C5H12‐containing mixtures. Combustion and Flame 156  (2009) 221–233

  8. 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

  9. Performance Measures for Student Assistants.

    ERIC Educational Resources Information Center

    Kathman, Jane McGurn; Kathman, Michael D.

    1992-01-01

    Argues that performance measures for student employees in academic libraries should set expectations for their performance and become management tools to motivate, evaluate, and reward them. Management literature on full-time employees is modified to fit students' needs, i.e., that they are part-time and not necessarily motivated by the work…

  10. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Measurements of gas parameters in plasma-assisted supersonic combustion processes using diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Bolshov, Mikhail A.; Kuritsyn, Yu A.; Liger, V. V.; Mironenko, V. R.; Leonov, S. B.; Yarantsev, D. A.

    2009-09-01

    We report a procedure for temperature and water vapour concentration measurements in an unsteady-state combustion zone using diode laser absorption spectroscopy. The procedure involves measurements of the absorption spectrum of water molecules around 1.39 μm. It has been used to determine hydrogen combustion parameters in M = 2 gas flows in the test section of a supersonic wind tunnel. The relatively high intensities of the absorption lines used have enabled direct absorption measurements. We describe a differential technique for measurements of transient absorption spectra, the procedure we used for primary data processing and approaches for determining the gas temperature and H2O concentration in the probed zone. The measured absorption spectra are fitted with spectra simulated using parameters from spectroscopic databases. The combustion-time-averaged (~50 ms) gas temperature and water vapour partial pressure in the hot wake region are determined to be 1050 K and 21 Torr, respectively. The large signal-to-noise ratio in our measurements allowed us to assess the temporal behaviour of these parameters. The accuracy in our temperature measurements in the probed zone is ~40 K.

  11. Austenitic stainless steel patterning by plasma assisted diffusion treatments

    NASA Astrophysics Data System (ADS)

    Czerwiec, T.; Marcos, G.; Thiriet, T.; Guo, Y.; Belmonte, T.

    2009-09-01

    The new concept of surface texturing or surface patterning on austenitic stainless steel by plasma assisted diffusion treatment is presented in this paper. It allows the creation of uniform micro or nano relief with regularly shaped asperities or depressions. Plasma assisted diffusion treatments are based on the diffusion of nitrogen and/or carbon in a metallic material at moderate to elevated temperatures. Below 420°C, a plasma assisted nitriding treatment of austenitic stainless steel produces a phase usually called expanded austenite. Expanded austenite is a metastable nitrogen supersaturated solid solution with a disordered fcc structure and a distorted lattice. The nitrided layer with the expanded austenite is highly enriched in nitrogen (from 10 to 35 at%) and submitted to high compressive residual stresses. From mechanical consideration, it is shown that the only possible deformation occurs in the direction perpendicular to the surface. Such an expansion of the layer from the initial surface of the substrate to the gas phase is used here for surface patterning of stainless steel parts. The surface patterning is performed by using masks (TEM grid) and multi-dipolar plasmas.

  12. NOX REDUCTION FOR LEAN EXHAUST USING PLASMA ASSISTED CATALYSIS

    SciTech Connect

    Bhatt, B.

    2000-08-20

    Currently CARB estimates on road diesel vehicles contribute 50% of the NOX and 78% of the particulates being discharged from mobile sources. Diesel emissions obviously must be reduced if future air quality targets are to be met. A critical technological barrier exists because there are no commercial technologies available, which can reduce NOX from diesel (lean), exhaust containing 5-15% O2 concentration. One promising approach to reducing NOX and particulates from diesel exhaust is to use a combination of plasma with catalyst. Plasma can be generated thermally or non-thermally. Thermal plasma is formed by heating the system to an exceedingly high temperature (>2000 C). High temperature requirements for plasma makes thermal plasma inefficient and requires skillful thermal management and hence is considered impractical for mobile applications. Non-thermal plasma directs electrical energy into the creation of free electrons, which in turn react with gaseous species thus creating plasma. A combination of non-thermal plasma with catalysts can be referred to Plasma Assisted Catalysts or PAC. PAC technology has been demonstrated in stationary sources where non-thermal plasma catalysis is carried out in presence of NH3 as a reductant. In stationary applications NO is oxidized to HNO3 and then into ammonium nitrate where it is condensed and removed. This approach is impractical for mobile application because of the ammonia requirement and the ultimate mechanism by which NOX is removed. However, if a suitable catalyst can be found which can use onboard fuel as reductant then the technology holds a considerable promise. NOX REDUCTION FOR LEAN EXHAUST USING PLASMA ASSISTED CATALYSIS Ralph Slone, B. Bhatt and Victor Puchkarev NOXTECH INC. In addition to the development of an effective catalyst, a non-thermal plasma reactor needs be scaled and demonstrated along with a reliable and cost effective plasma power source and onboard HC source needs to be proven. Under the work

  13. Plasma-assisted surface modification and radical diagnostics

    NASA Astrophysics Data System (ADS)

    Sugai, H.; Yamage, M.; Hikosaka, Y.; Nakano, T.; Toyoda, H.

    1993-05-01

    Plasma-assisted deposition and etching have widely been applied to microelectronics devices in industries as well as to huge vacuum devices in nuclear fusion. A more detailed understanding of plasma processing is essential for development of new techniques for small-scale ( < {1}/{4} μm ) etching and large-scale ( >10 m) deposition. A scaling law for uniformity of large-scale deposition was found in a simulation experiment of boron coating of fusion devices, using a less hazardous boride B 10H 14 (decaborane). Moreover, boron etching by a fluorocarbon plasma was demonstrated along with a new modeling of surface-coverage effects. Appearance mass spectrometry which is a powerful tool for neutral radical detection, has successfully been applied to a CF 4 containing RF plasma for semiconductor etching. Addition of a small amount of H 2 into CF 4 drastically modified the kinetics of CF 2 and CF 3 radicals as a result of surface processes.

  14. Photo-assisted etching of silicon in halogen-containing plasmas

    NASA Astrophysics Data System (ADS)

    Sridhar, Shyam; Zhu, Weiye; Liu, Lei; Economou, Demetre; Donnelly, Vincent

    2013-09-01

    Cl2, Br2, HBr, and HBr/Cl2 feed gases diluted in Ar were used to study etching of p-type Si(100) in a RF inductively coupled, Faraday-shielded plasma. Etching rates were measured as a function of ion energy. Etching at ion energies below the threshold for ion-assisted etching was observed in all cases, with Br2/Ar and HBr/Cl2/Ar plasmas having the lowest and highest sub-threshold etching rates, respectively. Sub-threshold etching rates scaled with the product of surface halogen coverage (measured by XPS) and Ar emission intensity (7504Å). Etching rates measured under MgF2, quartz, and opaque windows, or biased grids, showed that sub-threshold etching is due to photon-stimulated processes on the surface, with VUV photons being much more effective than longer wavelengths. Scanning electron and atomic force microscopy (SEM and AFM) revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. Photo-assisted etching in Cl2/Ar plasmas resulted in the formation of 4-sided pyramidal features with bases that form an angle of 45° with respect to < 110 > . cleavage planes, suggesting that the photo-assisted etching process is sensitive to crystal orientation, at least for chlorine. Work supported by DOE Plasma Science Center and NSF.

  15. Photo-assisted etching of silicon in chlorine- and bromine-containing plasmas

    NASA Astrophysics Data System (ADS)

    Zhu, Weiye; Sridhar, Shyam; Liu, Lei; Hernandez, Eduardo; Donnelly, Vincent M.; Economou, Demetre J.

    2014-05-01

    Cl2, Br2, HBr, Br2/Cl2, and HBr/Cl2 feed gases diluted in Ar (50%-50% by volume) were used to study etching of p-type Si(100) in a rf inductively coupled, Faraday-shielded plasma, with a focus on the photo-assisted etching component. Etching rates were measured as a function of ion energy. Etching at ion energies below the threshold for ion-assisted etching was observed in all cases, with Br2/Ar and HBr/Cl2/Ar plasmas having the lowest and highest sub-threshold etching rates, respectively. Sub-threshold etching rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 Å). Etching rates measured under MgF2, quartz, and opaque windows showed that sub-threshold etching is due to photon-stimulated processes on the surface, with vacuum ultraviolet photons being much more effective than longer wavelengths. Scanning electron and atomic force microscopy revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. Photo-assisted etching in Cl2/Ar plasmas resulted in the formation of 4-sided pyramidal features with bases that formed an angle of 45° with respect to ⟨110⟩ cleavage planes, suggesting that photo-assisted etching can be sensitive to crystal orientation.

  16. A high temperature, plasma-assisted chemical vapor deposition system

    SciTech Connect

    Brusasco, R.M.; Britten, J.A.; Thorsness, C.B.; Scrivener, M.S.; Unites, W.G.; Campbell, J.H. ); Johnson, W.L. )

    1990-02-01

    We have designed and built a high-temperature, plasma-assisted, chemical vapor deposition system to deposit multilayer optical coatings of SiO{sub 2} and doped-SiO{sub 2} flat substrates. The coater concept and design is an outgrowth of our recent work with Schott Glasswerke demonstrating the use of plasma assisted CVD to prepare very high damage threshold optical coatings. The coater is designed to deposit up to several thousand alternating quarterwave layers of SiO{sub 2} and doped SiO{sub 2} substrate at deposition rates up to several microns per minute. The substrate is resistively heated to about 1000{degree}C during the deposition phase of the process. The plasma is driven by a 13.56 MHz RF unit capable of producing power densities of up to 140 W cm{sup {minus}3} in the reaction zone. The coater is designed to be adaptable to microwave generated plasmas, as well as RF. Reactant gas flow rates of up to 10 slm can be achieved at a 10 tar operating pressure. Reactants consist of O{sub 2}, SiCl{sub 4} and a volatile halogenated dopant. These gases react in the plasma volume producing SiO{sub 2} with dopant concentrations of up to a few percent. A variable dopant concentration is used to produce index differences between adjacent optical layers.

  17. Observation of molecular assisted recombination in the magnetized sheet plasma

    NASA Astrophysics Data System (ADS)

    Tonegawa, Akira; Ogawa, Hironori; Yazawa, Hiroyuki; Ono, Masataka; Kawamura, Kazutaka

    2003-10-01

    Molecular assisted recombination (MAR) with vibrational hydorogen molecular has been observed to enhance the reduction of ion particle flux in a high density magnetized sheet plasma device (TPDSHEET-IV). There are two main paths for MAR: (1) H2(v) + e=> H- + H (dissociated attachment) followed by H- + H+ =>H + H (mutual neutralization), and (2) H2(v) + A+ => (AH)+ + H (ion conversion) followed by (AH)+ + e => A + H (dissociative recombination) , where A+(A) is a hydrogen or an impurity ion (atom) existing in the plasma. The value of H+, H2+ and H3+ are observed in the mid-plane region with hot electron(Te= 10-15 eV) by a mass-analyzer. On the other hand, negative ions of hydrogen atom H- is localized in the circumference of existing cold electrons (Te= 3-5 eV) by a probe assisted laser photodetachment method. A small amount of secondary hydrogen gas puffing into a hydrogen plasma decreased gradually the density of H2+, H3+ and increased rapidly H- in the plasma, while the conventional radiation and three-body recombination (EIR) processes were disappeared. These results can be well explained by taking the MAR in the plasma into account.

  18. Chemical analysis of plasma-assisted antimicrobial treatment on cotton

    NASA Astrophysics Data System (ADS)

    Kan, C. W.; Lam, Y. L.; Yuen, C. W. M.; Luximon, A.; Lau, K. W.; Chen, K. S.

    2013-06-01

    This paper explores the use of plasma treatment as a pretreatment process to assist the application of antimicrobial process on cotton fabric with good functional effect. In this paper, antimicrobial finishing agent, Microfresh Liquid Formulation 9200-200 (MF), and a binder (polyurethane dispersion, Microban Liquid Formulation R10800-0, MB) will be used for treating the cotton fabric for improving the antimicrobial property and pre-treatment of cotton fabric by plasma under atmospheric pressure will be employed to improve loading of chemical agents. The chemical analysis of the treated cotton fabric will be conducted by Fourier transform Infrared Spectroscopy.

  19. ISS Plasma Interaction: Measurements and Modeling

    NASA Technical Reports Server (NTRS)

    Barsamian, H.; Mikatarian, R.; Alred, J.; Minow, J.; Koontz, S.

    2004-01-01

    Ionospheric plasma interaction effects on the International Space Station are discussed in the following paper. The large structure and high voltage arrays of the ISS represent a complex system interacting with LEO plasma. Discharge current measurements made by the Plasma Contactor Units and potential measurements made by the Floating Potential Probe delineate charging and magnetic induction effects on the ISS. Based on theoretical and physical understanding of the interaction phenomena, a model of ISS plasma interaction has been developed. The model includes magnetic induction effects, interaction of the high voltage solar arrays with ionospheric plasma, and accounts for other conductive areas on the ISS. Based on these phenomena, the Plasma Interaction Model has been developed. Limited verification of the model has been performed by comparison of Floating Potential Probe measurement data to simulations. The ISS plasma interaction model will be further tested and verified as measurements from the Floating Potential Measurement Unit become available, and construction of the ISS continues.

  20. Plasma"anti-assistance" and"self-assistance" to high power impulse magnetron sputtering

    SciTech Connect

    Anders, Andre; Yushkov, Georgy Yu.

    2009-01-30

    A plasma assistance system was investigated with the goal to operate high power impulse magnetron sputtering (HiPIMS) at lower pressure than usual, thereby to enhance the utilization of the ballistic atoms and ions with high kinetic energy in the film growth process. Gas plasma flow from a constricted plasma source was aimed at the magnetron target. Contrary to initial expectations, such plasma assistance turned out to be contra-productive because it led to the extinction of the magnetron discharge. The effect can be explained by gas rarefaction. A better method of reducing the necessary gas pressure is operation at relatively high pulse repetition rates where the afterglow plasma of one pulse assists in the development of the next pulse. Here we show that this method, known from medium-frequency (MF) pulsed sputtering, is also very important at the much lower pulse repetition rates of HiPIMS. A minimum in the possible operational pressure is found in the frequency region between HiPIMS and MF pulsed sputtering.

  1. Plasma and Ion Assistance in Physical Vapor Deposition: AHistorical Perspective

    SciTech Connect

    Anders, Andre

    2007-02-28

    Deposition of films using plasma or plasma-assist can betraced back surprisingly far, namely to the 18th century for arcs and tothe 19th century for sputtering. However, only since the 1960s thecoatings community considered other processes than evaporation for largescale commercial use. Ion Plating was perhaps the first importantprocess, introducing vapor ionization and substrate bias to generate abeam of ions arriving on the surface of the growing film. Ratherindependently, cathodic arc deposition was established as an energeticcondensation process, first in the former Soviet Union in the 1970s, andin the 1980s in the Western Hemisphere. About a dozen various ion-basedcoating technologies evolved in the last decades, all characterized byspecific plasma or ion generation processes. Gridded and gridless ionsources were taken from space propulsion and applied to thin filmdeposition. Modeling and simulation have helped to make plasma and ionseffects to be reasonably well understood. Yet--due to the complex, oftennon-linear and non-equilibrium nature of plasma and surfaceinteractions--there is still a place for the experience plasma"sourcerer."

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

    PubMed

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

    2012-06-05

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

  3. Plasma assisted surface coating/modification processes - An emerging technology

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1987-01-01

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation. These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  4. Plasma assisted surface coating/modification processes: An emerging technology

    NASA Astrophysics Data System (ADS)

    Spalvins, T.

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation). These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  5. Plasma assisted surface coating/modification processes - An emerging technology

    NASA Astrophysics Data System (ADS)

    Spalvins, T.

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation. These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  6. Plasma assisted surface coating/modification processes - An emerging technology

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1987-01-01

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation. These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  7. Commercialization of Plasma-Assisted Technologies: The Indian Experience

    NASA Astrophysics Data System (ADS)

    John, P. I.

    The paper describes an initiative by the Institute for Plasma Research (IPR), India in establishing links with the Indian industry for developing and commercialising advanced plasma-based industrial technologies. This has culminated in the creation of a self-financing technology development, incubation, demonstration and delivery facility. A business plan for converting the knowledge base to commercially viable technologies conceived technology as a product and the industry as the market and addressed issues like resistance to new technologies, the key role of entrepreneur, thrust areas and the necessity of technology incubation and delivery. Success of this strategy is discussed in a few case studies. We conclude by identifying the cost, environmental, strategic and techno-economic aspects, which would be the prime drivers for plasma-assisted manufacturing technology in India.

  8. Plasma assisted surface coating/modification processes: An emerging technology

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1986-01-01

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation). These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  9. Dyslipidemia causes overestimation of plasma mitotane measurements

    PubMed Central

    Paci, Angelo; Hescot, Ségolène; Seck, Atmane; Jublanc, Christel; Mercier, Lionel; Vezzosi, Delphine; Drui, Delphine; Quinkler, Marcus; Fassnacht, Martin; Bruckert, Eric; Lombès, Marc; Leboulleux, Sophie; Broutin, Sophie

    2016-01-01

    Summary Mitotane (o,p′-DDD) is the standard treatment for advanced adrenocortical carcinoma (ACC). Monitoring of plasma mitotane levels is recommended to look for a therapeutic window between 14 and 20mg/L, but its positive predictive value requires optimization. We report the case of an ACC patient with a history of dyslipidemia treated with mitotane in whom several plasma mitotane levels >30mg/L were found together with an excellent neurological tolerance. This observation led us to compare theoretical or measured o,p′-DDD and o,p′-DDE levels in a series of normolipidemic and dyslipidemic plasma samples to explore potential analytical issues responsible for an overestimation of plasma mitotane levels. We demonstrate an overestimation of mitotane measurements in dyslipidemic patients. Mitotane and o,p′-DDE measurements showed a mean 20% overestimation in hypercholesterolemic and hypertriglyceridemic plasma, compared with normolipidemic plasma. The internal standard p,p′-DDE measurements showed a parallel decrease in hypercholesterolemic and hypertriglyceridemic plasma, suggesting a matrix effect. Finally, diluting plasma samples and/or using phospholipid removal cartridges allowed correcting such interference. Learning points Hypercholesterolemia (HCH) and hypertriglyceridemia (HTG) induce an overestimation of plasma mitotane measurements. We propose a routine monitoring of lipidemic status. We propose optimized methodology of measurement before interpreting high plasma mitotane levels. PMID:27298727

  10. Measuring the Plasma Density of a Ferroelectric Plasma Source in an Expanding Plasma

    SciTech Connect

    A. Dunaevsky; N.J. Fisch

    2003-10-02

    The initial density and electron temperature at the surface of a ferroelectric plasma source were deduced from floating probe measurements in an expanding plasma. The method exploits negative charging of the floating probe capacitance by fast flows before the expanding plasma reaches the probe. The temporal profiles of the plasma density can be obtained from the voltage traces of the discharge of the charged probe capacitance by the ion current from the expanding plasma. The temporal profiles of the plasma density, at two different distances from the surface of the ferroelectric plasma source, could be further fitted by using the density profiles for the expanding plasma. This gives the initial values of the plasma density and electron temperature at the surface. The method could be useful for any pulsed discharge, which is accompanied by considerable electromagnetic noise, if the initial plasma parameters might be deduced from measurements in expanding plasma.

  11. Hollow ballistic pendulum for plasma momentum measurements

    SciTech Connect

    Goncharov, S.F.; Pashinin, P.P.; Perov, V.Y.; Serov, R.V.; Yanovsky, V.P.

    1988-05-01

    A novel pendulum design: hollow ballistic pendulum: is suggested for plasma momentum measurements. It has an advantage over the pendula used earlier in laser plasma experiments of being insensitive to a momentum of matter evaporated and scattered by the pendulum wall exposed to the plasma, which usually exceeds plasma momentum to be measured. Simple expressions describing pendulum performance are derived, and requirements of shape and size are established. Using this kind of pendulum in experiments on laser acceleration of thin foils made it possible to measure the momentum of accelerated foil with an accuracy of about 10%.

  12. Plasma dragged microparticles as a method to measure plasma flows

    SciTech Connect

    Ticos, Catalin M.; Wang Zhehui; Delzanno, Gian Luca; Lapenta, Giovanni

    2006-10-15

    The physics of microparticle motion in flowing plasmas is studied in detail for plasmas with electron and ion densities n{sub e,i}{approx}10{sup 19} m{sup -3}, electron and ion temperatures of no more than 15 eV, and plasma flows on the order of the ion thermal speed, v{sub f}{approx}v{sub ti}. The equations of motion due to Coulomb interactions and direct impact with ions and electrons, of charge variation, as well as of heat exchange with the plasma, are solved numerically for isolated particles (or dust grains) of micron sizes. It is predicted that microparticles can survive in plasma long enough, and can be dragged in the direction of the local ion flow. Based on the theoretical analysis, we describe a new plasma flow measurement technique called microparticle tracer velocimetry (mPTV), which tracks microparticle motion in a plasma with a high-speed camera. The mPTV can reveal the directions of the plasma flow vectors at multiple locations simultaneously and at submillimeter scales, which is hard to achieve by most other techniques. Thus, mPTV can be used to study plasma flows produced in the laboratory.

  13. Plasma diagnostics of low pressure high power impulse magnetron sputtering assisted by electron cyclotron wave resonance plasma

    SciTech Connect

    Stranak, Vitezslav; Herrendorf, Ann-Pierra; Drache, Steffen; Bogdanowicz, Robert; Hippler, Rainer; Cada, Martin; Hubicka, Zdenek; Tichy, Milan

    2012-11-01

    This paper reports on an investigation of the hybrid pulsed sputtering source based on the combination of electron cyclotron wave resonance (ECWR) inductively coupled plasma and high power impulse magnetron sputtering (HiPIMS) of a Ti target. The plasma source, operated in an Ar atmosphere at a very low pressure of 0.03 Pa, provides plasma where the major fraction of sputtered particles is ionized. It was found that ECWR assistance increases the electron temperature during the HiPIMS pulse. The discharge current and electron density can achieve their stable maximum 10 {mu}s after the onset of the HiPIMS pulse. Further, a high concentration of double charged Ti{sup ++} with energies of up to 160 eV was detected. All of these facts were verified experimentally by time-resolved emission spectroscopy, retarding field analyzer measurement, Langmuir probe, and energy-resolved mass spectrometry.

  14. Experimental investigation on plasma-assisted combustion characteristics of premixed propane/air mixture

    NASA Astrophysics Data System (ADS)

    Liu, Xingjian; He, Liming; Yu, Jinlu; Zeng, Hao; Jin, Tao

    2015-06-01

    A detailed study on the plasma-assisted combustion (PAC) characteristics of premixed propane/air mixture is presented. The PAC is measured electrically, as well as optically with a multichannel spectrometer. The characteristics are demonstrated by stable combustion temperature and combustion stability limits, and the results are compared with conventional combustion (CC). Stable combustion temperature measurements show that the introduction of PAC into combustion system can increase the stable combustion temperature, and the increment is more notable with an increase of discharge voltage. Besides, the rich and weak limits of combustion stability are both enlarged when plasma is applied into the combustion process and the increase of discharge voltage results in the expansion of combustion stability limits as well. The measurements of temperature head and emission spectrum illustrate that the kinetic enhancement caused by reactive species in plasma is the main enhancement pathway for current combustion system.

  15. Plasma-assisted ignition and deflagration-to-detonation transition.

    PubMed

    Starikovskiy, Andrey; Aleksandrov, Nickolay; Rakitin, Aleksandr

    2012-02-13

    Non-equilibrium plasma demonstrates great potential to control ultra-lean, ultra-fast, low-temperature flames and to become an extremely promising technology for a wide range of applications, including aviation gas turbine engines, piston engines, RAMjets, SCRAMjets and detonation initiation for pulsed detonation engines. The analysis of discharge processes shows that the discharge energy can be deposited into the desired internal degrees of freedom of molecules when varying the reduced electric field, E/n, at which the discharge is maintained. The amount of deposited energy is controlled by other discharge and gas parameters, including electric pulse duration, discharge current, gas number density, gas temperature, etc. As a rule, the dominant mechanism of the effect of non-equilibrium plasma on ignition and combustion is associated with the generation of active particles in the discharge plasma. For plasma-assisted ignition and combustion in mixtures containing air, the most promising active species are O atoms and, to a smaller extent, some other neutral atoms and radicals. These active particles are efficiently produced in high-voltage, nanosecond, pulse discharges owing to electron-impact dissociation of molecules and electron-impact excitation of N(2) electronic states, followed by collisional quenching of these states to dissociate the molecules. Mechanisms of deflagration-to-detonation transition (DDT) initiation by non-equilibrium plasma were analysed. For longitudinal discharges with a high power density in a plasma channel, two fast DDT mechanisms have been observed. When initiated by a spark or a transient discharge, the mixture ignited simultaneously over the volume of the discharge channel, producing a shock wave with a Mach number greater than 2 and a flame. A gradient mechanism of DDT similar to that proposed by Zeldovich has been observed experimentally under streamer initiation.

  16. Investigation of the Millimeter-Wave Plasma Assisted CVD Reactor

    SciTech Connect

    Vikharev, A.; Gorbachev, A.; Kozlov, A.; Litvak, A.; Bykov, Yu.; Caplan, M.

    2006-01-03

    A polycrystalline diamond grown by the chemical vapor deposition (CVD) technique is recognized as a unique material for high power electronic devices owing to unrivaled combination of properties such as ultra-low microwave absorption, high thermal conductivity, high mechanical strength and chemical stability. Microwave vacuum windows for modern high power sources and transmission lines operating at the megawatt power level require high quality diamond disks with a diameter of several centimeters and a thickness of a few millimeters. The microwave plasma-assisted CVD technique exploited today to produce such disks has low deposition rate, which limits the availability of large size diamond disk windows. High-electron-density plasma generated by the millimeter-wave power was suggested for enhanced-growth-rate CVD. In this paper a general description of the 30 GHz gyrotron-based facility is presented. The output radiation of the gyrotron is converted into four wave-beams. Free localized plasma in the shape of a disk with diameter much larger than the wavelength of the radiation is formed in the intersection area of the wave-beams. The results of investigation of the plasma parameters, as well as the first results of diamond film deposition are presented. The prospects for commercially producing vacuum window diamond disks for high power microwave devices at much lower costs and processing times than currently available are outlined.

  17. Investigation of the Millimeter-Wave Plasma Assisted CVD Reactor

    SciTech Connect

    Vikharev, A; Gorbachev, A; Kozlov, A; Litvak, A; Bykov, Y; Caplan, M

    2005-07-21

    A polycrystalline diamond grown by the chemical vapor deposition (CVD) technique is recognized as a unique material for high power electronic devices owing to unrivaled combination of properties such as ultra-low microwave absorption, high thermal conductivity, high mechanical strength and chemical stability. Microwave vacuum windows for modern high power sources and transmission lines operating at the megawatt power level require high quality diamond disks with a diameter of several centimeters and a thickness of a few millimeters. The microwave plasma-assisted CVD technique exploited today to produce such disks has low deposition rate, which limits the availability of large size diamond disk windows. High-electron-density plasma generated by the millimeter-wave power was suggested for enhanced-growth-rate CVD. In this paper a general description of the 30 GHz gyrotron-based facility is presented. The output radiation of the gyrotron is converted into four wave-beams. Free localized plasma in the shape of a disk with diameter much larger than the wavelength of the radiation is formed in the intersection area of the wave-beams. The results of investigation of the plasma parameters, as well as the first results of diamond film deposition are presented. The prospects for commercially producing vacuum window diamond disks for high power microwave devices at much lower costs and processing times than currently available are outlined.

  18. Kinetic modeling and sensitivity analysis of plasma-assisted combustion

    NASA Astrophysics Data System (ADS)

    Togai, Kuninori

    Plasma-assisted combustion (PAC) is a promising combustion enhancement technique that shows great potential for applications to a number of different practical combustion systems. In this dissertation, the chemical kinetics associated with PAC are investigated numerically with a newly developed model that describes the chemical processes induced by plasma. To support the model development, experiments were performed using a plasma flow reactor in which the fuel oxidation proceeds with the aid of plasma discharges below and above the self-ignition thermal limit of the reactive mixtures. The mixtures used were heavily diluted with Ar in order to study the reactions with temperature-controlled environments by suppressing the temperature changes due to chemical reactions. The temperature of the reactor was varied from 420 K to 1250 K and the pressure was fixed at 1 atm. Simulations were performed for the conditions corresponding to the experiments and the results are compared against each other. Important reaction paths were identified through path flux and sensitivity analyses. Reaction systems studied in this work are oxidation of hydrogen, ethylene, and methane, as well as the kinetics of NOx in plasma. In the fuel oxidation studies, reaction schemes that control the fuel oxidation are analyzed and discussed. With all the fuels studied, the oxidation reactions were extended to lower temperatures with plasma discharges compared to the cases without plasma. The analyses showed that radicals produced by dissociation of the reactants in plasma plays an important role of initiating the reaction sequence. At low temperatures where the system exhibits a chain-terminating nature, reactions of HO2 were found to play important roles on overall fuel oxidation. The effectiveness of HO2 as a chain terminator was weakened in the ethylene oxidation system, because the reactions of C 2H4 + O that have low activation energies deflects the flux of O atoms away from HO2. For the

  19. Bandgap measurements and the peculiar splitting of E{sub 2}{sup H} phonon modes of In{sub x}Al{sub 1-x}N nanowires grown by plasma assisted molecular beam epitaxy

    SciTech Connect

    Tangi, Malleswararao; Mishra, Pawan; Janjua, Bilal; Ng, Tien Khee; Prabaswara, Aditya; Ooi, Boon S.; Anjum, Dalaver H.; Yang, Yang; Albadri, Abdulrahman M.; Alyamani, Ahmed Y.; El-Desouki, Munir M.

    2016-07-28

    The dislocation free In{sub x}Al{sub 1-x}N nanowires (NWs) are grown on Si(111) by nitrogen plasma assisted molecular beam epitaxy in the temperature regime of 490 °C–610 °C yielding In composition ranges over 0.50 ≤ x ≤ 0.17. We study the optical properties of these NWs by spectroscopic ellipsometry (SE), photoluminescence, and Raman spectroscopies since they possesses minimal strain with reduced defects comparative to the planar films. The optical bandgap measurements of In{sub x}Al{sub 1-x}N NWs are demonstrated by SE where the absorption edges of the NW samples are evaluated irrespective of substrate transparency. A systematic Stoke shift of 0.04–0.27 eV with increasing x was observed when comparing the micro-photoluminescence spectra with the Tauc plot derived from SE. The micro-Raman spectra in the NWs with x = 0.5 showed two-mode behavior for A{sub 1}(LO) phonons and single mode behavior for E{sub 2}{sup H} phonons. As for x = 0.17, i.e., high Al content, we observed a peculiar E{sub 2}{sup H} phonon mode splitting. Further, we observe composition dependent frequency shifts. The 77 to 600 K micro-Raman spectroscopy measurements show that both AlN- and InN-like modes of A{sub 1}(LO) and E{sub 2}{sup H} phonons in In{sub x}Al{sub 1-x}N NWs are redshifted with increasing temperature, similar to that of the binary III group nitride semiconductors. These studies of the optical properties of the technologically important In{sub x}Al{sub 1-x}N nanowires will path the way towards lasers and light-emitting diodes in the wavelength of the ultra-violet and visible range.

  20. Photo-assisted etching of silicon in chlorine- and bromine-containing plasmas

    SciTech Connect

    Zhu, Weiye; Sridhar, Shyam; Liu, Lei; Hernandez, Eduardo; Donnelly, Vincent M. Economou, Demetre J.

    2014-05-28

    Cl{sub 2}, Br{sub 2}, HBr, Br{sub 2}/Cl{sub 2}, and HBr/Cl{sub 2} feed gases diluted in Ar (50%–50% by volume) were used to study etching of p-type Si(100) in a rf inductively coupled, Faraday-shielded plasma, with a focus on the photo-assisted etching component. Etching rates were measured as a function of ion energy. Etching at ion energies below the threshold for ion-assisted etching was observed in all cases, with Br{sub 2}/Ar and HBr/Cl{sub 2}/Ar plasmas having the lowest and highest sub-threshold etching rates, respectively. Sub-threshold etching rates scaled with the product of surface halogen coverage (measured by X-ray photoelectron spectroscopy) and Ar emission intensity (7504 Å). Etching rates measured under MgF{sub 2}, quartz, and opaque windows showed that sub-threshold etching is due to photon-stimulated processes on the surface, with vacuum ultraviolet photons being much more effective than longer wavelengths. Scanning electron and atomic force microscopy revealed that photo-etched surfaces were very rough, quite likely due to the inability of the photo-assisted process to remove contaminants from the surface. Photo-assisted etching in Cl{sub 2}/Ar plasmas resulted in the formation of 4-sided pyramidal features with bases that formed an angle of 45° with respect to 〈110〉 cleavage planes, suggesting that photo-assisted etching can be sensitive to crystal orientation.

  1. Mechanism of plasma-assisted ignition for H2 and C1-C5 hydrocarbons

    NASA Astrophysics Data System (ADS)

    Starikovskiy, Andrey; Aleksandrov, Nikolay

    2016-09-01

    Nonequilibrium plasma demonstrates ability to control ultra-lean, ultra-fast, low-temperature flames and appears to be an extremely promising technology for a wide range of applications, including aviation GTEs, piston engines, ramjets, scramjets and detonation initiation for pulsed detonation engines. To use nonequilibrium plasma for ignition and combustion in real energetic systems, one must understand the mechanisms of plasma-assisted ignition and combustion and be able to numerically simulate the discharge and combustion processes under various conditions. A new, validated mechanism for high-temperature hydrocarbon plasma assisted combustion was built and allows to qualitatively describe plasma-assisted combustion close and above the self-ignition threshold. The principal mechanisms of plasma-assisted ignition and combustion have been established and validated for a wide range of plasma and gas parameters. These results provide a basis for improving various energy-conversion combustion systems, from automobile to aircraft engines, using nonequilibrium plasma methods.

  2. Electron-silane scattering cross section for plasma assisted processes

    NASA Astrophysics Data System (ADS)

    Verma, Pankaj; Kaur, Jaspreet; Antony, Bobby

    2017-03-01

    Silane is an important molecule with numerous applications to natural and technological plasmas. In such environments, where plasma assisted processes are vital, electron induced reactions play a major role in its chemistry. In view of this, electron induced scattering of molecules such as silane finds significance. This article reports a comprehensive study of electron impact cross sections for silane over a wide energy range. In particular, the emphasis is given in providing a complete dataset for various electron scattering events possible with silane. Such dataset is the need for the plasma modeling community. Moreover, literature survey shows that the cross section database for silane is fragmentary. To fill this void, we have computed the differential elastic, total, rotational excitation, and momentum transfer cross sections. Two formalisms that are reliable in their energy domain are employed to accomplish the task: the R-matrix method through QUANTEMOL-N at low incident energies and the spherical complex optical potential formalism at intermediate to high energies. Interestingly, the comparison of the present cross section exhibits a good concurrence with the previous data, wherever available.

  3. Measurement of Human Blood and Plasma Volumes

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Szalkay, H. G. H.

    1987-01-01

    Report reviews techniques for measuring blood-plasma volume in humans. Common technique of using radioactive iodine isotope to label plasma albumin involves unwarranted risks from low-level radiation. Report emphasizes techniques using Evans-blue-dye (T-1824) labeling of albumin, hematocrit or hemoglobin/hematocrit measurements, or blood densitometry. In Evans-blue-dye technique, plasma volume determined from decrease in dye concentration occurring after small amount of dye solution injected into circulatory system. Subjection of Evans blue dye to test for carcinogenicity gave negative results.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  5. PRECISE CHARGE MEASUREMENT FOR LASER PLASMA ACCELERATORS

    SciTech Connect

    Nakamura, Kei; Gonsalves, Anthony; Lin, Chen; Sokollik, Thomas; Shiraishi, Satomi; Tilborg, Jeroen van; Osterhoff, Jens; Donahue, Rich; Rodgers, David; Smith, Alan; Byrne, Warren; Leemans, Wim

    2011-07-19

    Cross-calibrations of charge diagnostics are conducted to verify their validity for measuring electron beams produced by laser plasma accelerators (LPAs). Employed diagnostics are a scintillating screen, activation based measurement, and integrating current transformer. The diagnostics agreed within {+-}8 %, showing that they can provide accurate charge measurements for LPAs provided they are used properly.

  6. Plasma Assisted Combustion: Fundamental Studies and Engine Applications

    NASA Astrophysics Data System (ADS)

    Lefkowitz, Joseph K.

    Successful and efficient ignition in short residence time environments or ultra-lean mixtures is a key technological challenge for the evolution of advanced combustion devices in terms of both performance and efficiency. To meet this challenge, interest in plasma assisted combustion (PAC) has expanded over the past 20 years. However, understanding of the underlying physical processes of ignition by plasma discharge remains elementary. In order to shed light on the key processes involved, two main thrusts of research were undertaken in this dissertation. First, demonstration of the applicability of plasma discharges in engines and engine-like environments was carried out using a microwave discharge and a nanosecond repetitively pulsed discharge in an internal combustion engine and a pulsed detonation engine, respectively. Major conclusions include the extension of lean ignition limits for both engines, significant reduction of ignition time for mixtures with large minimum ignition energy, and the discovery of the inter-pulse coupling effect of nanosecond repetitively pulsed (NRP) discharges at high frequency. In order to understand the kinetic processes that led to these improvements, the second thrust of research directly explored the chemical kinetic processes of plasma discharges with hydrocarbon fuels. For this purpose, a low pressure flow reactor with a NRP dielectric barrier discharge cell was assembled. The discharge cell was fitted with a Herriott type multipass mirror arrangement, which allowed quantitative laser absorption spectroscopy to be performed in situ during the plasma discharge. Experiments on methane and ethylene mixtures with oxygen, argon, and helium revealed the importance of low temperature oxidation pathways in PAC. In particular, oxygen addition reactions were shown to be of primary importance in the oxidation of these small hydrocarbons in the temperature range of 300-600 K. Kinetic modeling tools, including both a coupled plasma and

  7. Measurements of an expanding surface flashover plasma

    SciTech Connect

    Harris, J. R.

    2014-05-21

    A better understanding of vacuum surface flashover and the plasma produced by it is of importance for electron and ion sources, as well as advanced accelerators and other vacuum electronic devices. This article describes time-of-flight and biased-probe measurements made on the expanding plasma generated from a vacuum surface flashover discharge. The plasma expanded at velocities of 1.2–6.5 cm/μs, and had typical densities of 10{sup 10}–10{sup 12} cm{sup −3}. The expansion velocity of the plasma leading edge often exhibited a sharp increase at distances of about 50 mm from the discharge site. Comparison with biased-probe data suggests that, under most conditions, the plasma leading edge was dominated by negative ions, with the apparent increase in velocity being due to fast H{sup −} overtaking slower, heavier ions. In some cases, biased-probe data also showed abrupt discontinuities in the plasma energy distribution co-located with large changes in the intercepted plasma current, suggesting the presence of a shock in the leading edge of the expanding plasma.

  8. A PLASIMO global model for plasma assisted CO2 conversion

    NASA Astrophysics Data System (ADS)

    Graef, Wouter; Rehman, Tafizur; Mihailova, Diana; van Dijk, Jan

    2014-10-01

    Conversion of CO2 has become a major challenge of our time as it is of interest for the reduction of greenhouse gases in our atmosphere, but also to store energy thereby relieving the supply and demand discrepancy of many alternative forms of energy. Plasma assisted CO2 conversion is heavily investigated as an efficient method to achieve this goal. Numerical modeling is an important aspect of this investigation, but is difficult due to the complex chemistry. A global model has been constructed to focus on the CO2 chemistry including its vibrational kinetics. The model has been realized using the global model module of PLASIMO, a highly modular plasma modeling framework. It is based on another model that was constructed using the well-established code Global_kin. The aim of the model is therefore twofold. First, to study the chemistry and identify the most important species and reactions and perform parametric studies. The knowledge gained can be applied to other, spatially resolved models. Second, by implementing the same chemistry in the two different global model codes, a cross validation can be performed, a vital scientific process often overlooked in practice.

  9. Simple and inexpensive microwave plasma assisted CVD facility

    SciTech Connect

    Brewer, M.A.; Brown, I.G.; Dickinson, M.R.

    1992-12-01

    A simple and inexpensive microwave plasma assisted CVD facility has been developed and used for synthesis of diamond thin films. The system is similar to those developed by others but includes several unique features that make it particularly economical and safe, yet capable of producing high quality diamond films. A 2.45 GHz magnetron from a commercial microwave oven is used as the microwave power source. A conventional mixture of 0.5% methane in hydrogen is ionized in a bell jar reaction chamber located within a simple microwave cavity. By using a small hydrogen reservoir adjacent to the gas supply, an empty hydrogen tank can be replaced without interrupting film synthesis or causing any drift in plasma characteristics. Hence, films can be grown continuously while storing only a 24-hour supply of explosive gases. System interlocks provide safe start-up and shut-down, and allow unsupervised operation. Here the authors describe the electrical, microwave and mechanical aspects of the system, and summarize the performance of the facility as used to reproducibly synthesize high quality diamond thin films.

  10. Matrix-Assisted Plasma Atomization Emission Spectrometry for Surface Sampling Elemental Analysis

    PubMed Central

    Yuan, Xin; Zhan, Xuefang; Li, Xuemei; Zhao, Zhongjun; Duan, Yixiang

    2016-01-01

    An innovative technology has been developed involving a simple and sensitive optical spectrometric method termed matrix-assisted plasma atomization emission spectrometry (MAPAES) for surface sampling elemental analysis using a piece of filter paper (FP) for sample introduction. MAPAES was carried out by direct interaction of the plasma tail plume with the matrix surface. The FP absorbs energy from the plasma source and releases combustion heating to the analytes originally present on its surface, thus to promote the atomization and excitation process. The matrix-assisted plasma atomization excitation phenomenon was observed for multiple elements. The FP matrix served as the partial energy producer and also the sample substrate to adsorb sample solution. Qualitative and quantitative determinations of metal ions were achieved by atomic emission measurements for elements Ba, Cu, Eu, In, Mn, Ni, Rh and Y. The detection limits were down to pg level with linear correlation coefficients better than 0.99. The proposed MAPAES provides a new way for atomic spectrometry which offers advantages of fast analysis speed, little sample consumption, less sample pretreatment, small size, and cost-effective. PMID:26762972

  11. Matrix-Assisted Plasma Atomization Emission Spectrometry for Surface Sampling Elemental Analysis.

    PubMed

    Yuan, Xin; Zhan, Xuefang; Li, Xuemei; Zhao, Zhongjun; Duan, Yixiang

    2016-01-14

    An innovative technology has been developed involving a simple and sensitive optical spectrometric method termed matrix-assisted plasma atomization emission spectrometry (MAPAES) for surface sampling elemental analysis using a piece of filter paper (FP) for sample introduction. MAPAES was carried out by direct interaction of the plasma tail plume with the matrix surface. The FP absorbs energy from the plasma source and releases combustion heating to the analytes originally present on its surface, thus to promote the atomization and excitation process. The matrix-assisted plasma atomization excitation phenomenon was observed for multiple elements. The FP matrix served as the partial energy producer and also the sample substrate to adsorb sample solution. Qualitative and quantitative determinations of metal ions were achieved by atomic emission measurements for elements Ba, Cu, Eu, In, Mn, Ni, Rh and Y. The detection limits were down to pg level with linear correlation coefficients better than 0.99. The proposed MAPAES provides a new way for atomic spectrometry which offers advantages of fast analysis speed, little sample consumption, less sample pretreatment, small size, and cost-effective.

  12. Measurement of electronegativity at different laser wavelengths: accuracy of Langmuir probe assisted laser photo-detachment

    NASA Astrophysics Data System (ADS)

    Sirse, N.; Oudini, N.; Bendib, A.; Ellingboe, A. R.

    2016-08-01

    Langmuir probe (LP) assisted pulsed laser photo-detachment (LPD) of negative ions is one of the frequently used diagnostic techniques in electronegative plasmas. The technique is based on measuring the rise in electron saturation current following photo-detachment. During the photo-detachment process it is assumed that the background electron parameters (temperature and density) remain unchanged in the laser channel and the photo-detached electrons thermalize instantaneously with the background electrons (same temperature). Therefore, the measured electronegativity should be independent of laser wavelengths. However, our recent simulation results (2015 Phys. Plasmas 22 073509) demonstrates a failure of these assumptions and suggests that the measured rise in electron saturation current has a dependence on the laser wavelength. This letter presents experimental evidence in support of these simulation results. In this work, photo-detachment is performed at two different laser wavelengths in an oxygen inductively coupled plasma discharge. Electronegativity measured by LP assisted LPD is compared with those obtained by the hairpin probe (HPP) assisted LPD which is based on quasi-neutrality assumption. The experimental results reveal that the electronegativities measured by LP assisted LPD are affected by the laser wavelength, whereas, electronegativities measured by HPP assisted LPD are almost independent. The discrepancy between the measurements is higher at high electronegativities. In conclusion, the experimental results validate the weakness of assumptions to estimate electronegativity from LPD combined with LP and therefore emphasizes the need of a more realistic model to analyze raw data or an alternate solution is to utilize HPP.

  13. Template-assisted generation of nanocavities within plasma polymer films.

    PubMed

    Vasilev, Krasimir; Casanal, Ana; Challougui, Hela; Griesser, Hans J

    2009-05-21

    The generation of nanosized cavities within thin film layers is of interest for a number of fundamental and applied reasons. One challenge is to make such systems sufficiently robust mechanically. Plasma polymer (pp) films possess excellent mechanical stability if deposition conditions are selected such as to achieve a sufficient density of cross-linking and resistance to extraction of polymeric material by solvents. In this study, gold nanoparticles of 15 and 70 nm diameter were used as sacrificial templates to generate nanocavities in pp films of various thickness values in the tens of nanometers range. A first pp layer was deposited onto substrates using n-heptylamine (HA) to a thickness of 20 nm. Carboxy-thiolated gold nanoparticles were electrostatically bound onto the surface amine groups of the n-heptylamine plasma polymer (HApp) layer. A second HApp layer was then coated to various thicknesses onto the nanoparticle/HApp surface. The template particles embedded thus in-between the two HApp layers were then dissolved using aqueous KCN solution; monitoring of the plasmon resonance band of the gold nanoparticles enabled verification of template stripping and measurement of the kinetics of stripping. AFM topography images showed little change on extraction of the template nanoparticles, indicating that the plasma polymer layer maintained structural integrity upon template extraction and subsequent drying, and thereby prevented collapse of the empty nanocavities. The concept of template stripping to generate controlled size free volume in thin plasma polymer layers is thus shown to produce robust structures.

  14. Development of plasma assisted thermal vapor deposition technique for high-quality thin film

    NASA Astrophysics Data System (ADS)

    Lee, Kang-Il; Choi, Yong Sup; Park, Hyun Jae

    2016-12-01

    The novel technique of Plasma-Assisted Vapor Deposition (PAVD) is developed as a new deposition method for thin metal films. The PAVD technique yields a high-quality thin film without any heating of the substrate because evaporated particles acquire energy from plasma that is confined to the inside of the evaporation source. Experiments of silver thin film deposition have been carried out in conditions of pressure lower than 10-3 Pa. Pure silver plasma generation is verified by the measurement of the Ag-I peak using optical emission spectroscopy. A four point probe and a UV-VIS spectrophotometer are used to measure the electrical and optical properties of the silver film that is deposited by PAVD. For an ultra-thin silver film with a thickness of 6.5 nm, we obtain the result of high-performance silver film properties, including a sheet resistance <20 Ω sq-1 and a visible-range transmittance >75%. The PAVD-film properties show a low sheet resistance of 30% and the same transmittance with conventional thermal evaporation film. In the PAVD source, highly energetic particles and UV from plasma do not reach the substrate because the plasma is completely shielded by the optimized nozzle of the crucible. This new PAVD technique could be a realistic solution to improve the qualities of transparent electrodes for organic light emission device fabrication without causing damage to the organic layers.

  15. Development of plasma assisted thermal vapor deposition technique for high-quality thin film.

    PubMed

    Lee, Kang-Il; Choi, Yong Sup; Park, Hyun Jae

    2016-12-01

    The novel technique of Plasma-Assisted Vapor Deposition (PAVD) is developed as a new deposition method for thin metal films. The PAVD technique yields a high-quality thin film without any heating of the substrate because evaporated particles acquire energy from plasma that is confined to the inside of the evaporation source. Experiments of silver thin film deposition have been carried out in conditions of pressure lower than 10(-3) Pa. Pure silver plasma generation is verified by the measurement of the Ag-I peak using optical emission spectroscopy. A four point probe and a UV-VIS spectrophotometer are used to measure the electrical and optical properties of the silver film that is deposited by PAVD. For an ultra-thin silver film with a thickness of 6.5 nm, we obtain the result of high-performance silver film properties, including a sheet resistance <20 Ω sq(-1) and a visible-range transmittance >75%. The PAVD-film properties show a low sheet resistance of 30% and the same transmittance with conventional thermal evaporation film. In the PAVD source, highly energetic particles and UV from plasma do not reach the substrate because the plasma is completely shielded by the optimized nozzle of the crucible. This new PAVD technique could be a realistic solution to improve the qualities of transparent electrodes for organic light emission device fabrication without causing damage to the organic layers.

  16. Plasma Measurements in an Integrated-System FARAD Thruster

    NASA Technical Reports Server (NTRS)

    Polzin, K. A.; Rose, M. F.; Miller, R.; Best, S.

    2007-01-01

    Pulsed inductive plasma accelerators are spacecraft propulsion devices in which energy is stored in a capacitor and then discharged through an inductive coil. The device is electrodeless, inducing a current sheet in a plasma located near the face of the coil. The propellant is accelerated and expelled at a high exhaust velocity (order of 10 km/s) through the interaction of the plasma current and the induced magnetic field. The Faraday Accelerator with RF-Assisted Discharge (FARAD) thruster[1,2] is a type of pulsed inductive plasma accelerator in which the plasma is preionized by a mechanism separate from that used to form the current sheet and accelerate the gas. Employing a separate preionization mechanism allows for the formation of an inductive current sheet at much lower discharge energies and voltages than those used in previous pulsed inductive accelerators like the Pulsed Inductive Thruster (PIT). A benchtop FARAD thruster was designed following guidelines and similarity performance parameters presented in Refs. [3,4]. This design is described in detail in Ref. [5]. In this paper, we present the temporally and spatially resolved measurements of the preionized plasma and inductively-accelerated current sheet in the FARAD thruster operating with a Vector Inversion Generator (VIG) to preionize the gas and a Bernardes and Merryman circuit topology to provide inductive acceleration. The acceleration stage operates on the order of 100 J/pulse. Fast-framing photography will be used to produce a time-resolved, global view of the evolving current sheet. Local diagnostics used include a fast ionization gauge capable of mapping the gas distribution prior to plasma initiation; direct measurement of the induced magnetic field using B-dot probes, induced azimuthal current measurement using a mini-Rogowski coil, and direct probing of the number density and electron temperature using triple probes.

  17. Comparative research of plasma-assisted milling and traditional milling in synthesizing AlN

    NASA Astrophysics Data System (ADS)

    Wang, Sen; Wang, Wenchun; Liu, Zhijie; Yang, Dezheng

    2017-06-01

    In this paper, traditional milling and discharge plasma-assisted milling are employed to synthesize aluminum nitride (AlN) powder at nanometer scale by milling the mixture of aluminum and lithium hydroxide monohydrate. AlN powders can be generated in traditional milling and plasma-assisted milling in an hour milling time. Differential thermal analysis curves show that the reaction temperature of the powders treated by plasma-assisted milling is lower than that of traditional milling. These results indicate that plasma-assisted milling has higher efficiency in the synthesis of AlN, getting smaller crystallite size and activating powder. Moreover, an optical emission spectrum is employed to demonstrate the active species in plasma. The different formation process of AlN in the two-milling process, and the promotion effects of plasma in the milling process are discussed.

  18. Plasma momentum meter for momentum flux measurements

    DOEpatents

    Zonca, F.; Cohen, S.A.; Bennett, T.; Timberlake, J.R.

    1993-08-24

    An apparatus is described for measuring momentum flux from an intense plasma stream, comprising: refractory target means oriented normal to the flow of said plasma stream for bombardment by said plasma stream where said bombardment by said plasma stream applies a pressure to said target means, pendulum means for communicating a translational displacement of said target to a force transducer where said translational displacement of said target is transferred to said force transducer by an elongated member coupled to said target, where said member is suspended by a pendulum configuration means and where said force transducer is responsive to said translational displacement of said member, and force transducer means for outputting a signal representing pressure data corresponding to said displacement.

  19. Bodies in flowing plasmas - Spacecraft measurements

    NASA Technical Reports Server (NTRS)

    Samir, U.

    1981-01-01

    Results are reviewed from in-situ measurements relevant to the interaction of bodies in flowing plasmas. A brief discussion is given of the interaction in the general context of space plasma physics, including possible applications to solar-system plasmas. Attention is given to the mode of experimentation in the Shuttle/Spacelab era. It is noted that the majority of in-situ investigations during the past decade were limited to the very near surface of ionospheric satellites. It is expected that experiments to be carried out on board the Spacelab/Orbiter will make possible well-planned controlled experiments in the area of body-plasma interactions in its widest sense.

  20. Electron density measurements for plasma adaptive optics

    NASA Astrophysics Data System (ADS)

    Neiswander, Brian W.

    Over the past 40 years, there has been growing interest in both laser communications and directed energy weapons that operate from moving aircraft. As a laser beam propagates from an aircraft in flight, it passes through boundary layers, turbulence, and shear layers in the near-region of the aircraft. These fluid instabilities cause strong density gradients which adversely affect the transmission of laser energy to a target. Adaptive optics provides corrective measures for this problem but current technology cannot respond quickly enough to be useful for high speed flight conditions. This research investigated the use of plasma as a medium for adaptive optics for aero-optics applications. When a laser beam passes through plasma, its phase is shifted proportionally to the electron density and gas heating within the plasma. As a result, plasma can be utilized as a dynamically controllable optical medium. Experiments were carried out using a cylindrical dielectric barrier discharge plasma chamber which generated a sub-atmospheric pressure, low-temperature plasma. An electrostatic model of this design was developed and revealed an important design constraint relating to the geometry of the chamber. Optical diagnostic techniques were used to characterize the plasma discharge. Single-wavelength interferometric experiments were performed and demonstrated up to 1.5 microns of optical path difference (OPD) in a 633 nm laser beam. Dual-wavelength interferometry was used to obtain time-resolved profiles of the plasma electron density and gas heating inside the plasma chamber. Furthermore, a new multi-wavelength infrared diagnostic technique was developed and proof-of-concept simulations were conducted to demonstrate the system's capabilities.

  1. Reflectometric measurement of plasma imaging and applications

    NASA Astrophysics Data System (ADS)

    Mase, A.; Ito, N.; Oda, M.; Komada, Y.; Nagae, D.; Zhang, D.; Kogi, Y.; Tobimatsu, S.; Maruyama, T.; Shimazu, H.; Sakata, E.; Sakai, F.; Kuwahara, D.; Yoshinaga, T.; Tokuzawa, T.; Nagayama, Y.; Kawahata, K.; Yamaguchi, S.; Tsuji-Iio, S.; Domier, C. W.; Luhmann, N. C., Jr.; Park, H. K.; Yun, G.; Lee, W.; Padhi, S.; Kim, K. W.

    2012-01-01

    Progress in microwave and millimeter-wave technologies has made possible advanced diagnostics for application to various fields, such as, plasma diagnostics, radio astronomy, alien substance detection, airborne and spaceborne imaging radars called as synthetic aperture radars, living body measurements. Transmission, reflection, scattering, and radiation processes of electromagnetic waves are utilized as diagnostic tools. In this report we focus on the reflectometric measurements and applications to biological signals (vital signal detection and breast cancer detection) as well as plasma diagnostics, specifically by use of imaging technique and ultra-wideband radar technique.

  2. Microwave Plasma Assisted Combustion of Premixed Ar/CH4 and He/CH4 Gases at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Wang, Chuji; Srivastava, Nimisha; Malik Kaya, Burak

    2010-11-01

    Low-temperature nonthermal plasma assisted combustion is of growing interest due to potential applications in the improvement of combustion efficiency, reduction of ignition delay time, fuel reforming, etc. A 2.45 GHz microwave plasma source was used to study the microwave plasma enhanced flame of premixed Ar/CH4 and He/CH4 gases at atmospheric pressure. We present the visual observations of the plasma-assisted flames sustained at different mixing ratios of Ar/CH4 and He/CH4 gases. Optical emission spectroscopy (OES) was employed to study the reactive species generated from plasma flame. Visual imaging clearly showed the effect of microwave power and difference in flame shapes created in the Ar/CH4 and He/CH4 combustion: for Ar/CH4 continuous flames were observed; for He/CH4 floating flames (flames sustained with an air-gap from the plasma orifice) were observed at low plasma powers and some particular gas mixing ratios of He/CH4. Measured flame temperatures were much higher than plasma gas temperatures. Reactive species, such as OH, NO, N2, and C2, were observed using OES. Effect of various gas mixing ratios, flow rates, and plasma powers on flame shape and flame temperature were also studied.

  3. Inductive Measurement of Plasma Jet Electrical Conductivity

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  4. Design of a Microwave Assisted Discharge Inductive Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley K.; Polzin, Kurt A.

    2010-01-01

    The design and construction of a thruster that employs electrodeless plasma preionization and pulsed inductive acceleration is described. Preionization is achieved through an electron cyclotron resonance discharge that produces a weakly-ionized plasma at the face of a conical theta pinch-shaped inductive coil. The presence of the preionized plasma allows for current sheet formation at lower discharge voltages than those employed in other pulsed inductive accelerators that do not employ preionization. The location of the electron cyclotron resonance discharge is controlled through the design of the applied magnetic field in the thruster. Finite element analysis shows that there is an arrangement of permanent magnets that yields a small volume of resonant magnetic field at the coil face. Preionization in the resonant zone leads to current sheet formation at the coil face, which minimizes the initial inductance of the pulse circuit and maximizes the potential electrical efficiency of the accelerator. A magnet assembly was constructed around an inductive coil to provide structural support to the selected arrangement of neodymium magnets. Measured values of the resulting magnetic field compare favorably with the finite element model.

  5. Characterization of GaN microstructures grown by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Lo, Ikai; Pang, Wen-Yuan; Hsu, Yu-Chi; Hsieh, Chia-Ho; Shih, Cheng-Hung; Chou, Mitch M. C.; Chen, Wen-Yen; Hsu, Tzu-Min; Hsu, Gary Z. L.

    2013-06-15

    The characterization of GaN microstructures grown by plasma-assisted molecular beam epitaxy on LiAlO{sub 2} substrate was studied by cathodoluminescence and photoluminescence measurements. We demonstrated that the cathodoluminescence from oblique semi-polar surfaces of mushroom-shaped GaN was much brighter than that from top polar surface due to the reduction of polarization field on the oblique semi-polar surfaces. It implies that the oblique semi-polar surface is superior for the light-emitting surface of wurtzite nano-devices.

  6. Plasma Measurement Strategies for Solar Sailcraft

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H.; Garbe, Greg

    2004-01-01

    Solar sailcraft offer enabling capabilities for achieving future space physics mission objectives. These sailcraft will be the largest platforms that space physics missions will potentially use. The electromagnetic interaction of the sailcraft with the local environment is of keen interest. Plasma measurement strategies for a validation mission and for operational missions are discussed.

  7. High Current Hollow Cathode Plasma Plume Measurements

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Kamhawi, Hani; Williams, George J., Jr.

    2014-01-01

    Plasma plume measurements are reported for a hollow cathode assembly (HCA) operated at discharge currents of 50, 70, and 100 A at xenon flow rates between 19 - 46 standard cubic centimeter per minute. The HCA was centrally mounted in the NASA-300MS Hall Thruster and was operated in the "spot" and "plume" modes with additional data taken with an applied magnetic field. Langmuir probes, retarding potential analyzers, and optical emission spectroscopy were employed to measure plasma properties near the orifice of the HCA and to assess the charge state of the near-field plasma. Electron temperatures (2-6 electron volt) and plasma potentials are consistent with probe-measured values in previous investigations. Operation with an applied-field yields higher discharge voltages, increased Xe III production, and increased signals from the 833.5 nm C I line. While operating in plume mode and with an applied field, ion energy distribution measurements yield ions with energies significantly exceeding the applied discharge voltage. These findings are correlated with high-frequency oscillations associated with each mode.

  8. Subtractive Plasma-Assisted-Etch Process for Developing High Performance Nanocrystalline Zinc-Oxide Thin-Film-Transistors

    DTIC Science & Technology

    2015-03-26

    SUBTRACTIVE PLASMA -ASSISTED- ETCH PROCESS FOR DEVELOPING HIGH PERFORMANCE NANOCRYSTALLINE ZINC-OXIDE...Government and is not subject to copyright protection in the United States. AFIT-ENG-MS-15-M-027 SUBTRACTIVE PLASMA -ASSISTED- ETCH PROCESS FOR...15-M-027 SUBTRACTIVE PLASMA -ASSISTED- ETCH PROCESS FOR DEVELOPING HIGH PERFORMANCE NANOCRYSTALLINE ZINC-OXIDE THIN-FILM-TRANSISTORS Thomas

  9. Silicon fluxes in the scrape-off layer plasma during silicon-assisted operation of TEXTOR

    NASA Astrophysics Data System (ADS)

    Rubel, M.; Wienhold, P.; Almqvist, N.; Emmoth, B.; Esser, H. G.; Könen, L.; von Seggern, J.; Winter, J.

    1995-04-01

    Surface collector probes were applied at TEXTOR for the investigation of silicon fluxes in the scrape-off layer during the first silicon-assisted (silane puffing, siliconization) operation of a tokamak. Probe exposures were made in order to measure the evolution of Si fluxes and the influence of silicon on the behaviour of other impurity fluxes like boron, oxygen and metals. Studies were performed under different conditions: heating mode, plasma density and gas filling. Comparative exposures were made before introduction of Si into the machine as well as immediately and long time after the siliconization. The exposed graphite samples were examined by surface analysis techniques, including Auger electron and Rutherford backscattering spectroscopies, nuclear reaction analysis and ultra-high resolution microscopies. The most important findings are concerned with: (i) the relation between silicon to carbon and silicon to oxygen in the deposits; (ii) the change in radial profiles of Si, B and D fluxes during consecutive stages of the silicon-assisted operation, and the retention of deuterium in the Si containing codeposited layers. The influence of plasma density on the fluxes is considered and gettering of oxygen by silicon is also addressed. Comparison is also made to the results of VUV spectroscopy signals of silicon and oxygen impurities in the plasma.

  10. Plasma-assisted atomic layer deposition of conformal Pt films in high aspect ratio trenches

    NASA Astrophysics Data System (ADS)

    Erkens, I. J. M.; Verheijen, M. A.; Knoops, H. C. M.; Keuning, W.; Roozeboom, F.; Kessels, W. M. M.

    2017-02-01

    To date, conventional thermal atomic layer deposition (ALD) has been the method of choice to deposit high-quality Pt thin films grown typically from (MeCp)PtMe3 vapor and O2 gas at 300 °C. Plasma-assisted ALD of Pt using O2 plasma can offer several advantages over thermal ALD, such as faster nucleation and deposition at lower temperatures. In this work, it is demonstrated that plasma-assisted ALD at 300 °C also allows for the deposition of highly conformal Pt films in trenches with high aspect ratio ranging from 3 to 34. Scanning electron microscopy inspection revealed that the conformality of the deposited Pt films was 100% in trenches with aspect ratio (AR) up to 34. These results were corroborated by high-precision layer thickness measurements by transmission electron microscopy for trenches with an aspect ratio of 22. The role of the surface recombination of O-radicals and the contribution of thermal ALD reactions is discussed.

  11. Plasma-assisted atomic layer deposition of conformal Pt films in high aspect ratio trenches.

    PubMed

    Erkens, I J M; Verheijen, M A; Knoops, H C M; Keuning, W; Roozeboom, F; Kessels, W M M

    2017-02-07

    To date, conventional thermal atomic layer deposition (ALD) has been the method of choice to deposit high-quality Pt thin films grown typically from (MeCp)PtMe3 vapor and O2 gas at 300 °C. Plasma-assisted ALD of Pt using O2 plasma can offer several advantages over thermal ALD, such as faster nucleation and deposition at lower temperatures. In this work, it is demonstrated that plasma-assisted ALD at 300 °C also allows for the deposition of highly conformal Pt films in trenches with high aspect ratio ranging from 3 to 34. Scanning electron microscopy inspection revealed that the conformality of the deposited Pt films was 100% in trenches with aspect ratio (AR) up to 34. These results were corroborated by high-precision layer thickness measurements by transmission electron microscopy for trenches with an aspect ratio of 22. The role of the surface recombination of O-radicals and the contribution of thermal ALD reactions is discussed.

  12. Direct-Coupled Plasma-Assisted Combustion Using a Microwave Waveguide Torch

    DTIC Science & Technology

    2011-12-01

    be the foundation of an improved energy infrastructure by facilitating highly efficient thermal energy conversion through plasma -assisted combustion... plasma discharge was conducted to investigate the thermal nature of the discharge. The heating of the gas flow can be calculated from the increase in... plasma energy as heat decreases. From this data, it is demonstrated that the thermal effects are lesser in a plasma -enhanced flame than in air and lesser

  13. Temperature dependence of inductively coupled plasma assisted growth of TiN thin films.

    SciTech Connect

    Meng, W. J.; Curtis, T. J.; Rehn, L. E.; Baldo, P. M.; Materials Science Division; Louisiana State Univ.

    1999-11-01

    The use of low pressure high density plasmas to assist the synthesis of ceramic thin film materials is in its infancy. Using an inductively coupled plasma assisted magnetron sputtering system, we examine the dependence of plasma-assisted growth of TiN thin films on growth temperature at different ratios of ion flux to neutral atom flux. Our results indicate that a temperature independent densification of TiN films occurs above a certain ion to neutral atom flux ratio. As an example of this temperature independent densification, we demonstrate the formation of dense B1 TiN crystalline thin films at growth temperatures down to {approx}100 K.

  14. First measurements of plasma waves near Mars

    NASA Technical Reports Server (NTRS)

    Grard, R.; Pedersen, A.; Klimov, S.; Savin, S.; Skalskii, A.

    1989-01-01

    Preliminary results from electric field measurements in the environment of Mars using the plasma-wave system on board Phobos 2 are reported. Electron-plasma oscillations observed upstream of the bow shock correspond to a solar-wind density of 2/cu cm. The shock-foot boundary was crossed up to three times on each orbit. The shock ramp was detected at altitudes between 0.45 and 0.75 Mars radii R(M) above the planetary surface. The density increased by about a factor of two at the ramp. The shock position, although variable, seems to be consistent with previous measurements. The downstream magnetosheath contained broadband electric-field noise below the plasma frequency. The boundary of th obstacle, or plasmapause, was crossed at altitudes of the order of 0.28 R(M); the cold plasma density was highly variable within the planetopause and reached the unexpected value of 700/cu cm on the third orbit, at 0.25 R(M) altitude. Bursts of waves with frequencies below the electron cyclotron frequency occur within the planetopause.

  15. High Current Hollow Cathode Plasma Plume Measurements

    NASA Technical Reports Server (NTRS)

    Thomas, Robert E.; Kamhawi, Hani; Williams, George J., Jr.

    2013-01-01

    Plasma plume measurements are reported for a hollow cathode assembly (HCA) oper-ated at discharge currents of 50, 70, and 100 A at xenon ow rates between 19 - 46 sccm.The HCA was centrally mounted in the annulus of the NASA-300MS Hall Thruster andwas operated in the spot and plume modes with additional data taken with an appliedmagnetic eld. Langmuir probes, retarding potential analyzers, and optical emission spec-troscopy were employed to measure plasma properties near the orice of the HCA and toassess the charge state of the near-eld plasma. Electron temperatures (2-6 eV) and plasmapotentials are consistent with probe-measured values in previous investigations. Operationwith an applied-eld yields higher discharge voltages, increased Xe III production, andincreased signals from the 833.5 nm C I line. While operating in plume mode and with anapplied eld, ion energy distribution measurements yield ions with energies signicantlyexceeding the applied discharge voltage. These ndings are correlated with high-frequencyoscillations associated with each mode.

  16. Radio Plasma Imager Simulations and Measurements

    NASA Technical Reports Server (NTRS)

    Green, J. L.; Benson, R. F.; Fung, S. F.; Taylor, W. W. L.; Boardsen, S. A.; Reinisch, B. W.; Haines, D. M.; Bibl, K.; Cheney, G.; Galkin, I. A.

    1999-01-01

    The Radio Plasma Imager (RPI) will be the first-of-its kind instrument designed to use radio wave sounding techniques to perform repetitive remote sensing measurements of electron number density (N(sub e)) structures and the dynamics of the magnetosphere and plasmasphere. RPI will fly on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) mission to be launched early in the year 2000. The design of the RPI is based on recent advances in radio transmitter and receiver design and modern digital processing techniques perfected for ground-based ionospheric sounding over the last two decades. Free-space electromagnetic waves transmitted by the RPI located in the low density magnetospheric cavity will be reflected at distant plasma cutoffs. The location and characteristics of the plasma at those remote reflection points can then be derived from measurements of the echo amplitude, phase, delay time, frequency, polarization, Doppler shift, and echo direction. The 500 m tip-to-tip X and Y (spin plane) antennas and 20 m boom Z axis antenna on RPI will be used to measures echoes coming from distances of several R(sub E).

  17. Super-paramagnetic nanoparticles synthesis in a thermal plasma reactor assisted by magnetic bottle

    NASA Astrophysics Data System (ADS)

    Cartaya, R.; Puerta, J.; Martín, P.

    2015-03-01

    The present work is a study of the synthesis of super-paramagnetic particles. A preliminary study based on thermodynamic diagrams of Gibbs free energy minimization, was performed with the CSIRO Thermochemical System. In this way, the synthesis of magnetite nanoparticles from precursor powder of ore iron in a thermal reactor, was performed. Then the process was simulated mathematically using magnetohydrodynamic and kinetic equations, in order to predict the synthesis process. A cylindrical reactor assisted by magnetic mirrors was used. The peak intensity of 0.1 tesla (1000 Gauss) was measured at the end of the solenoid. A PlazjetTM 105/15 thermal plasma torch was used. The precursor powder was iron oxide and the plasma gas, nitrogen. The magnetite powder was magnetized whit rare-earth super-magnets, alloy of neodymium-iron boron (NdFeB) grade N-42. The synthesized nanoparticles diameters was measured with a scanning electron microscope LECO and the permanent magnetization with a YOKOGAWA gauss meter, model 325i. Our experimental results show that it is possible the synthesis of super-paramagnetic nanoparticles in thermal plasma reactors.

  18. Measurements of the Plasma Parameters and Low Frequency Oscillations in the Fisk Plasma Source

    NASA Technical Reports Server (NTRS)

    Thomas, Edward, Jr.; Wallace, Kent; Lampkin, Gregory; Watson, Michael

    1998-01-01

    A new plasma device, the Fisk Plasma Source (FPS), has been developed at Fisk University. This plasma device is used to study the physics of low temperature plasmas and plasma-material interactions. The FPS device is a stainless steel vacuum 6-way cross vacuum vessel with at 10-inch inner diameter. Low temperature argon plasmas are generated using DC glow discharge and thermionic filament techniques. Spatial profiles of the plasma density, plasma potential, and electron temperature are measured using Langmuir probes. We present initial experimental measurements of density and temperature profiles in the FPS device. Experimental and theoretical studies of low frequency oscillations observed in the FPS device are also presented.

  19. Measurement of reactive species for plasma medicine

    NASA Astrophysics Data System (ADS)

    Ono, Ryo

    2015-09-01

    Plasma medicine has been intensively studied over the last decade. Reactive oxygen and nitrogen species are responsible for the therapeutic effects in plasma medicine. To examine the therapeutic effects of reactive species, the densities of OH, O, and NO were measured using laser-induced fluorescence (LIF). A helium atmospheric-pressure plasma jet (10 kV, 10 kHz of 40 μs pulses) and a nanosecond streamer discharge (24 kV, 8 ns, 30 Hz) were utilized to treat mouse melanoma cells in a culture medium. Correlation between the dose of reactive species and deactivation rate of melanoma cells was measured with the aid of LIF. The results showed that the rate of cell death correlates with OH density, but not with O and NO densities. Next, a method to supply a specific reactive species to living organisms was developed. It utilizes photolysis of helium-buffered H2O and O2 by vacuum ultraviolet (VUV) light to produce reactive species. The VUV method was utilized to sterilize Bacillus atrophaeus on agar plate. With the VUV method, it was succeeded to show sterilization only by OH radicals. A 30 s treatment with approximately 0.1 ppm OH radicals caused visible sterilization.

  20. Direct observation of the optical plasma resonance of Ag by photon-assisted tunneling

    NASA Technical Reports Server (NTRS)

    Jain, R. K.; Farrier, M. G.; Gustafson, T. K.

    1976-01-01

    Photon-assisted tunneling is proposed for the investigation of optical plasma resonances; this is demonstrated by the direct observation of the Ag resonance in appropriate Ag-Al2O3-Al structures. A spectral scan of the ratio of the signals photoinduced by the p and s polarizations shows a large enhancement corresponding to the plasma resonance of Ag.

  1. Ultrathin gate oxide with a reduced transition layer grown by plasma-assisted oxidation

    SciTech Connect

    Hyun, S.; Buh, G.H.; Hong, S.H.; Koo, B.Y.; Shin, Y.G.; Jung, U.I.; Moon, J.T.; Cho, M.-H.; Chang, H.S.; Moon, D.W.

    2004-08-09

    Ultrathin SiO{sub 2} grown by plasma-assisted oxidation (plasma oxide) has been investigated by high-resolution x-ray photoemission spectroscopy and medium energy ion scattering spectroscopy. We found that the plasma oxide grown at the low temperature of 400 deg. C has a thinner transition layer than conventional thermal oxide. This thinner transition layer in the plasma oxide not only decreased the gate leakage current effectively, but also enhanced the reliability of the gate oxide. We attribute these electrical properties of the plasma oxide to the reduction of the transition layer.

  2. Efficiency of a hybrid-type plasma-assisted fuel reformation system

    SciTech Connect

    Matveev, I.B.; Serbin, S.I.; Lux, S.M.

    2008-12-15

    The major advantages of a new plasma-assisted fuel reformation system are its cost effectiveness and technical efficiency. Applied Plasma Technologies has proposed its new highly efficient hybrid-type plasma-assisted system for organic fuel combustion and gasification. The system operates as a multimode multipurpose reactor in a wide range of plasma feedstock gases and turndown ratios. This system also has convenient and simultaneous feeding of several reagents in the reaction zone such as liquid fuels, coal, steam, and air. A special methodology has been developed for such a system in terms of heat balance evaluation and optimization. This methodology considers all existing and possible energy streams, which could influence the system's efficiency. The developed hybrid-type plasma system could be suitable for combustion applications, mobile and autonomous small- to mid-size liquid fuel and coal gasification modules, hydrogen-rich gas generators, waste-processing facilities, and plasma chemical reactors.

  3. INTERPRETING POWER ANISOTROPY MEASUREMENTS IN PLASMA TURBULENCE

    SciTech Connect

    Chen, C. H. K.; Wicks, R. T.; Horbury, T. S.; Schekochihin, A. A.

    2010-03-10

    A relationship is derived between power anisotropy and wavevector anisotropy in turbulent fluctuations. This can be used to interpret plasma turbulence measurements, for example, in the solar wind. If fluctuations are spatially anisotropic, then the ion gyroscale break point in measured spectra in the directions parallel and perpendicular to the magnetic field would not occur at the same frequency, and similarly for the electron gyroscale break point. This is an important consideration when interpreting solar wind measurements in terms of anisotropic turbulence theories. Model magnetic field power spectra are presented assuming a cascade of critically balanced Alfven waves in the inertial range and kinetic Alfven waves in the dissipation range. The variation of power anisotropy with scale is compared to existing solar wind measurements, and the similarities and differences are discussed.

  4. Compton scattering measurements from dense plasmas

    DOE PAGES

    Glenzer, S. H.; Neumayer, P.; Doppner, T.; ...

    2008-06-12

    Here, Compton scattering techniques have been developed for accurate measurements of densities and temperatures in dense plasmas. One future challenge is the application of this technique to characterize compressed matter on the National Ignition Facility where hydrogen and beryllium will approach extremely dense states of matter of up to 1000 g/cc. In this regime, the density, compressibility, and capsule fuel adiabat may be directly measured from the Compton scattered spectrum of a high-energy x-ray line source. Specifically, the scattered spectra directly reflect the electron velocity distribution. In non-degenerate plasmas, the width provides an accurate measure of the electron temperatures, whilemore » in partially Fermi degenerate systems that occur in laser-compressed matter it provides the Fermi energy and hence the electron density. Both of these regimes have been accessed in experiments at the Omega laser by employing isochorically heated solid-density beryllium and moderately compressed beryllium foil targets. In the latter experiment, compressions by a factor of 3 at pressures of 40 Mbar have been measured in excellent agreement with radiation hydrodynamic modeling.« less

  5. ECE Measurements of Helical Plasmas in LHD

    NASA Astrophysics Data System (ADS)

    Nagayama, Y.; Inagaki, S.; Ito, Y.; Kawahata, K.; Sasao, H.; de Vries, P.

    1999-11-01

    This paper presents ECE measurements on LHD, which is the l=2, n=10 heriotron with the major radius of 3.8 m, with the averaged minor radius of 60 cm and with the helical field of up to 3 T. The ECE is collected from both inner and outer sides, since the magnetic field has a peaked profile. ECE is detcted with Michelson, GPC and 70 GHz and 140 GHz radiometers. The LHD plasma is generated using ECH of up to 1 MW and is heated using NBI of up to 8 GW. Notch filters reduce the ECH leakage. The polarization of ECE is theoretically and experimentally investigated in the heriotoron system, where the field angle rotates -30 to 30^o. The polarization follows as the field angle changes. Since the density profile is flat, ECE is cut off in the edge region in the high density LHD plasma. An interesting observation is the breathing phenomena, which is as follows: the electron temperature and other plasma parameters oscillate with frequency of 0.5-1Hz like a sine-wave when the NBI power is about 1 MW.

  6. Quantum-memory-assisted entropic uncertainty relations under weak measurements

    NASA Astrophysics Data System (ADS)

    Li, Lei; Wang, Qing-Wen; Shen, Shu-Qian; Li, Ming

    2017-08-01

    We investigate quantum-memory-assisted entropic uncertainty relations (EURs) based on weak measurements. It is shown that the lower bound of EUR revealed by weak measurements is always larger than that revealed by the corresponding projective measurements. A series of lower bounds of EUR under both weak measurements and projective measurements are presented. Interestingly, the quantum-memory-assisted EUR based on weak measurements is a monotonically decreasing function of the strength parameter. Furthermore, some information-theoretic inequalities associated with weak measurements are also derived.

  7. Measuring Assistive Technology Outcomes in Schools Using Functional Assessment.

    ERIC Educational Resources Information Center

    Silverman, Michelle Kaye; Stratman, Kristine Freiberg; Smith, Roger O.

    2000-01-01

    Activities of Project OATS (Outcomes of Assistive Technology in the Schools) are described, including identification and piloting of existing assessment instruments for use as an outcome measure, examining the validity of the School Function Assessment, and field testing the School Function Assessment-Assistive Technology Version, an adaptation of…

  8. Measuring Assistive Technology Outcomes in Schools Using Functional Assessment.

    ERIC Educational Resources Information Center

    Silverman, Michelle Kaye; Stratman, Kristine Freiberg; Smith, Roger O.

    2000-01-01

    Activities of Project OATS (Outcomes of Assistive Technology in the Schools) are described, including identification and piloting of existing assessment instruments for use as an outcome measure, examining the validity of the School Function Assessment, and field testing the School Function Assessment-Assistive Technology Version, an adaptation of…

  9. Measurement of Debye length in laser-produced plasma.

    NASA Technical Reports Server (NTRS)

    Ehler, W.

    1973-01-01

    The Debye length of an expanded plasma created by placing an evacuated chamber with an entrance slit in the path of a freely expanding laser produced plasma was measured, using the slab geometry. An independent measurement of electron density together with the observed value for the Debye length also provided a means for evaluating the plasma electron temperature. This temperature has applications in ascertaining plasma conductivity and magnetic field necessary for confinement of the laser produced plasma. Also, the temperature obtained would be useful in analyzing electron-ion recombination rates in the expanded plasma and the dynamics of the cooling process of the plasma expansion.

  10. Plasma momentum meter for momentum flux measurements

    DOEpatents

    Zonca, Fulvio; Cohen, Samuel A.; Bennett, Timothy; Timberlake, John R.

    1993-01-01

    Invention comprises an instrument in which momentum flux onto a biasable target plate is transferred via a suspended quartz tube onto a sensitive force transducer--a capacitance-type pressure gauge. The transducer is protected from thermal damage, arcing and sputtering, and materials used in the target and pendulum are electrically insulating, rigid even at elevated temperatures, and have low thermal conductivity. The instrument enables measurement of small forces (10.sup.-5 to 10.sup.3 N) accompanied by high heat fluxes which are transmitted by energetic particles with 10's of eV of kinetic energy in a intense magnetic field and pulsed plasma environment.

  11. Measured emissivities of uranium and tungsten plasmas.

    NASA Technical Reports Server (NTRS)

    Miller, M. H.

    1971-01-01

    Uranium and tungsten absorption coefficients between 2,500-8500 A were measured as functions of thermodynamic variables. A gas-driven shock tube was used to obtain plasma temperatures, heavy metal partial pressures, and total pressures in the ranges 7,000-12,000 K, 0.02-1.0 atm, and 3.0-48 atm, respectively. Emission and absorption data were recorded both photographically and photoelectrically. The spectral distributions, thermal dependence and line-to-continuum ratios of the uranium and tungsten radiation differ distinctly. The uranium data are compared with theoretical predictions and with results from other experiments.

  12. Measured emissivities of uranium and tungsten plasmas.

    NASA Technical Reports Server (NTRS)

    Miller, M. H.

    1971-01-01

    Uranium and tungsten absorption coefficients between 2,500-8500 A were measured as functions of thermodynamic variables. A gas-driven shock tube was used to obtain plasma temperatures, heavy metal partial pressures, and total pressures in the ranges 7,000-12,000 K, 0.02-1.0 atm, and 3.0-48 atm, respectively. Emission and absorption data were recorded both photographically and photoelectrically. The spectral distributions, thermal dependence and line-to-continuum ratios of the uranium and tungsten radiation differ distinctly. The uranium data are compared with theoretical predictions and with results from other experiments.

  13. Propane decomposition and conversion into other hydrocarbons using metal target assisted laser induced plasma

    NASA Astrophysics Data System (ADS)

    Moosakhani, A.; Parvin, P.; Reyhani, A.; Mortazavi, S. Z.

    2017-01-01

    It is shown that the propane molecules are strongly decomposed in the metal assisted laser induced plasma based on the nano-catalytic adsorption. A Q-Switched Nd:YAG laser is employed to irradiate the propane gas filled in the control chamber in the presence of the reactive metals such as Ni, Fe, Pd, and Cu in order to study the effect of catalysts during the decomposition. The catalytic targets simultaneously facilitate the plasma formation and the decomposition events leading to generate a wide distribution of the light and heavy hydrocarbon molecules, mainly due to the recombination processes. Fourier transform infrared spectroscopy and gas chromatography instruments support the findings by detecting the synthetic components. Furthermore, the optical emission spectroscopy of the laser induced plasma emissions realizes the real time monitoring of the reactions taking place during each laser shot. The subsequent recombination events give rise to the generation of a variety of the hydrocarbon molecules. The dissociation rate, conversion ratio, selectivity, and yield as well as the performance factor arise mainly from the catalytic effects of the metal species. Moreover, the ablation rate of the targets of interest is taken into account as a measure of the catalytic reactivity due to the abundance of the metal species ablated from the target. This leads to assess the better performance factor for Pd among four metal catalysts of interest during propane decomposition. Finally, the molecules such as ethane and ethylene are identified as the stable abundant species created during the successive molecular recombination processes.

  14. Plasma-Assisted ALD of an Al2O3 Permeation Barrier Layer on Plastic

    NASA Astrophysics Data System (ADS)

    Lei, Wenwen; Li, Xingcun; Chen, Qiang; Wang, Zhengduo

    2012-02-01

    Atomic layer deposition (ALD) technique is used in the preparation of organic/inorganic layers, which requires uniform surfaces with their thickness down to several nanometers. For film with such thickness, the growth mode defined as the arrangement of clusters on the surface during the growth is of significance. In this work, Al2O3 thin film was deposited on various interfacial species of pre-treated polyethylene terephthalate (PET, 12 μm) by plasma assisted atomic layer deposition (PA-ALD), where trimethyl aluminium was used as the Al precursor and O2 as the oxygen source. The interfacial species, -NH3, -OH, and -COOH as well as SiCHO (derived from monomer of HMDSO plasma), were grafted previously by plasma and chemical treatments. The growth mode of PA-ALD Al2O3 was then investigated in detail by combining results from in-situ diagnosis of spectroscopic ellipsometry (SE) and ex-situ characterization of as-deposited layers from the morphologies scanned by atomic force microscopy (AFM). In addition, the oxygen transmission rates (OTR) of the original and treated plastic films were measured. The possible reasons for the dependence of the OTR values on the surface species were explored.

  15. Plasma-Assisted Atomic Layer Growth of High-Quality Aluminum Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Jeong, Chang-Wook; Lee, Jang-Sik; Joo, Seung-Ki

    2001-01-01

    Thin aluminum oxide (Al2O3) films were grown by the plasma-assisted atomic layer controlled deposition (PAALD) method using Dimethylethylamine alane [(CH3)2(C2H5)N:AlH3] (DMEAA). Al was deposited by the PAALD method, then the Al films were oxidized into Al2O3 by plasma oxidation in the same chamber without breaking the vacuum. Al2O3 thin films of 15 nm thickness were prepared by repetition of this process. Thus prepared Al2O3 thin films exhibited a refractive index of 1.68. The thickness and the refractive index fluctuation of the film over a 4 inch wafer were ±2.3% and ±1.9%, respectively, for the deposited films. The leakage current density and breakdown field were measured to be about 10-8 A/cm2 at 1 MV/cm and 7 MV/cm, respectively. Considerable improvement of the electrical properties was realized by the post oxygen-plasma annealing at 200°C.

  16. Design of a Microwave Assisted Discharge Inductive Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley K.; Polzin, Kurt A.

    2010-01-01

    A new plasma accelerator concept that employs electrodeless plasma preionization and pulsed inductive acceleration is presented. Preionization is achieved through an electron cyclotron resonance discharge that produces a weakly-ionized plasma at the face of a conical theta pinch-shaped inductive coil. The presence of the preionized plasma allows for current sheet formation at lower discharge voltages than those found in other pulsed inductive accelerators. The location of an electron cyclotron resonance discharge can be controlled through the design of the applied magnetic field in the thruster. A finite-element model of the magnetic field was used as a design tool, allowing for the implementation of an arrangement of permanent magnets that yields a small volume of preionized propellant at the coil face. This allows for current sheet formation at the face of the inductive coil, minimizing the initial inductance of the pulse circuit and maximizing the potential efficiency of the new accelerator.

  17. Fast steel-cleanness characterization by means of laser-assisted plasma spectrometric methods.

    PubMed

    Müller, Gregor; Stahnke, Frank; Bleiner, Davide

    2006-12-15

    Laser-assisted plasma spectrometry is a palette of analytical techniques (L-OES, LA-ICP-MS) capable of fast spatially-resolved elemental analysis in the micrometer range. For fast estimation of the occurrence in steel samples of non-metallic inclusions, which degrade the material's technical properties, simultaneous OES detection and sequential ICP-MS detection were compared. Histograms were obtained for the intensity distribution of the acquired signals (laser pulse statistics). The skewness coefficient of the histograms for Al (indicator of non-metallic inclusions) was found to be clearly dependent on the fraction of non-metallic inclusions in the case of scanning L-OES. For LA-ICP-MS less clear dependence was observed, which was influenced by the acquisition characteristics. In fact, less measurement throughput limited for LA-ICP-MS the counting statistics to an extent that overrides the benefit of higher detection power as compared to L-OES.

  18. Cold-plasma assisted hydrophobisation of cellulose fibres with styrene and para-halogenated homologues

    NASA Astrophysics Data System (ADS)

    Gaiolas, C.; Costa, A. P.; Santos Silva, M. J.; Belgacem, M. N.

    2012-07-01

    Cold-plasma-assisted treatment of additive-free hand sheet paper samples with styrene (ST), para-fluorostyrene (FST), para-fluoro-α-methylstyrene (FMST) and para-chloro-α-methylstyrene (ClMST) and para-bromostyrene (BrST) was studied and found that the grafting has occurred efficiently, as established by contact angle measurement. Thus, after solvent extraction of the modified substrates, in order to remove unbounded grafts, the contact angle value of a drop of water deposited at the surface of paper increased from 40° for unmodified substrate to 102, 99, 116, 100 and 107°, for ST-, FST- FMST-, ClMST- and BrST-treated samples, respectively, indicating that the surface has became totally hydrophobic. In fact, the polar component of the surface energy of treated samples decreased from 25 mJ/m2 to practically zero, indicating that treated surfaces were rendered totally non polar.

  19. Growth of MoO3 films by oxygen plasma assisted molecular beam epitaxy

    SciTech Connect

    Altman, Eric I.; Droubay, Timothy C.; Chambers, Scott A.

    2002-07-22

    The growth of MoO₃ films on SrLaAlO₄(0 0 1), a substrate lattice-matched to b-MoO , by oxygen plasma assisted molecular beam epitaxy was characterized using reflection high-energy electron diffraction (RHEED), X-ray photoelectron spectroscopy, Xray diffraction (XRD), and atomic force and scanning tunneling microscopies (AFM and STM).It was found that the flux of reactive oxygen species to the surface was not high enough to maintain the proper stoichiometry, even at the lowest measurable deposition rates. Therefore, the films were grown by depositing Mo in small increments and then allowing the Mo to oxidize. At 675 K, the films grew epitaxially but in a three-dimensional manner. XRD of films grown under these conditions revealed atetragonal structure that has not been previously observed in bulk MoO₃ samples.

  20. Acquisition of Mechanically Assisted Spark Plasma Sintering System for Advanced Research and Education on Functionally Graded Hybrid Materials

    DTIC Science & Technology

    2012-03-14

    March 14, 2012 Final Progress Report September 15, 2010 - December 14, 2011 ACQUISITION OF MECHANICALLY ASSISTED SPARK PLASMA SINTERING SYSTEM FOR...Instrumentation Program (DURIP) Project titled, “Acquisition of Mechanically Assisted Spark Plasma Sintering System for Advanced Research and Education...at developing facilities for pressure-assisted fabrication of hybrid materials by spark plasma sintering (SPS) of metallic and ceramic powders to

  1. Effects of assisted magnetic field to an atmospheric-pressure plasma jet on radical generation at the plasma-surface interface and bactericidal function

    NASA Astrophysics Data System (ADS)

    Liu, Chih-Tung; Kumakura, Takumi; Ishikawa, Kenji; Hashizume, Hiroshi; Takeda, Keigo; Ito, Masafumi; Hori, Masaru; Wu, Jong-Shinn

    2016-12-01

    A configuration of magnetic-assisted-plasma (MAP) on helium-based atmospheric-pressure plasma jet (APPJ) with an axial magnetic-field of 0.587 T is proposed, which provides good ability for killing bacteria Escherichia coli on the agar surface. Optically, we confirmed that the MAP increased approximately 2.4 times in the electron density estimated by the Stark broadening of H β line emission, and approximately 1.5 times enhancement of atomic oxygen concentration measured by vacuum ultraviolet absorption spectroscopy (VUVAS). Moreover, the generation of hydroxyl radical in the water increased 1.5 times, confirmed by the spin-trapping electron spin-resonance technique. In addition, the bactericidal experiments demonstrated 2.4 times higher for E. coli by the MAP treatment. The MAP configuration is proposed to be highly useful for future bio-medical applications by enhancing the radical generation at the plasma/substrate interface region.

  2. Electron Heating in Microwave-Assisted Helicon Plasmas

    NASA Astrophysics Data System (ADS)

    McKee, John; Siddiqui, Umair; Jemiolo, Andrew; McIlvain, Julianne; Scime, Earl

    2016-10-01

    The use of two (or more) rf sources at different frequencies is a common technique in the plasma processing industry to control ion energy characteristics separately from plasma generation. A similar approach is presented here with the focus on modifying the electron population in argon and helium plasmas. The plasma is generated by a helicon source at a frequency f 0 = 13.56 MHz. Mcrowaves of frequency f 1 = 2.45 GHz are then injected into the helicon source chamber perpendicular to the background magnetic field. The microwaves damp on the electrons via X-mode Electron Cyclotron Heating (ECH) at the upper hybrid resonance, providing additional energy input into the electrons. The effects of this secondary-source heating on electron density, temperature, and energy distribution function are examined and compared to helicon-only single source plasmas as well as numeric models suggesting that the heating is not evenly distributed but spatially localized. Optical Emission Spectroscopy (OES) is used to examine the impact of the energetic tail of the electron distribution on ion and neutral species via collisional excitation. Large enhancements of neutral spectral lines are observed with little to no enhancement of ion lines.

  3. Synthesis of magnetic nanoparticles by atmospheric-pressure glow discharge plasma-assisted electrolysis

    NASA Astrophysics Data System (ADS)

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

    2017-07-01

    For the synthesis of magnetic nanoparticles (NPs), we used plasma-assisted electrolysis in which atmospheric-pressure DC glow discharge using a liquid electrode is combined with electrolysis. The solution surface is exposed to positive ions or electrons in plasma. To synthesize magnetic NPs, aqueous solutions of FeCl2 or an iron electrode immersed in liquid was used to supply iron ions in the liquid. Magnetic NPs were synthesized at the plasma-liquid interface upon the electron irradiation of the liquid surface. In the case of using aqueous solutions of FeCl2, the condition of magnetic NP synthesis depended on the gas species of plasma and the chemical agent in the liquid for controlling oxidization. The amount of magnetic NPs synthesized using plasma is not very large. On the other hand, in the case of using an iron electrode immersed in NaCl solution, magnetic NPs were synthesized without using FeCl2 solutions. When plasma-assisted electrolysis was operated, the iron electrode eluted Fe cations, resulting in the formation of magnetic NPs at the plasma-liquid interface. Magnetic NP synthesis depended on the concentration of NaCl solution and discharge current. The magnetic NPs were identified to be magnetite. By using this method, more magnetite NPs were synthesized than in the case of plasma-assisted electrolysis with FeCl2 aqueous solutions. The pH of the liquid used in plasma-assisted electrolysis was important for the synthesis of magnetite NPs.

  4. Modeling and Simulation of Plasma-Assisted Ignition and Combustion

    DTIC Science & Technology

    2013-10-01

    GRI Mech 3.0 has been validated extensively in 1000-2500 K and 25 torr to 10 atm range. • USC Mech has been validated in 900-2500 K and 16 torr to...64 species) GRI Mech 3.0 CH4/N2/O2 plasma NOX reactions C2H4-air (70 species) USC Mech C2H4/N2/O2 plasma NOX reactions Pi = 100 torr...3 -15 kV peak voltage 7 ns FWHM Mdot : 0.00377 kg/m2-s GRI Mech 3.0 + CH4/N2/O2/CO/CO2 plasma + NOX chemistry CH4-air validation of flame

  5. Spectroscopic measurements of temperature in a weakly nonideal plasma

    SciTech Connect

    Mitrofanov, N.K.

    1995-04-01

    Application of traditional spectroscopic techniques for determining the temperature in a plasma by measuring the spectral line intensities is incorrect, even for a weakly nonideal plasma. The method of relative intensities of spectral lines and a continuum is modified taking into account a decrease in the line intensity caused by ionization in a plasma microfield. Comparison of temperature measurements in an atmospheric-pressure arc plasma performed by traditional and modified methods supports the validity of our approach.

  6. Energy Measurement in a Plasma Wakefield Accelerator

    SciTech Connect

    Ischebeck, R

    2007-07-06

    In the E-167 plasma wakefield acceleration experiment, electrons with an initial energy of 42GeV are accelerated in a meter-scale lithium plasma. Particles are leaving plasma with a large energy spread. To determine the spectrum of the accelerated particles, a two-plane spectrometer has been set up.

  7. Electron Temperature and Plasma Flow Measurements of NIF Hohlraum Plasmas

    NASA Astrophysics Data System (ADS)

    Barrios, M. A.; Liedahl, D. A.; Schneider, M. B.; Jones, O.; Brow, G. V.; Regan, S. P.; Fournier, K. B.; Moore, A. S.; Ross, J. S.; Eder, D.; Landen, O.; Kauffman, R. L.; Nikroo, A.; Kroll, J.; Jaquez, J.; Huang, H.; Hansen, S. B.; Callahan, D. A.; Hinkel, D. E.; Bradley, D.; Moody, J. D.; LLNL Collaboration; LLE Collaboration; GA Collaboration; SNL Collaboration

    2016-10-01

    Characterizing the plasma conditions inside NIF hohlraums, in particular mapping the plasma Te, is critical to gaining insight into mechanisms that affect energy coupling and transport in the hohlraum. The dot spectroscopy platform provides a temporal history of the localized Te and plasma flow inside a NIF hohlraum, by introducing a Mn-Co tracer dot, at strategic locations inside the hohlraum, that comes to equilibrium with the local plasma. K-shell X-ray spectroscopy of the tracer dot is recorded onto an absolutely calibrated X-ray streak spectrometer. Isoelectronic and interstage line ratios are used to infer localized Te through comparison with atomic physics calculations using SCRAM. Time resolved X-ray images are simultaneously taken of the expanding dot, providing plasma (ion) flow information. We present recent results provided by this platform and compare with simulations using HYDRA. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

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

    NASA Astrophysics Data System (ADS)

    Noland, Jonathan David

    2011-12-01

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

  9. Aerosol-assisted plasma deposition of hydrophobic polycations makes surfaces highly antimicrobial.

    PubMed

    Liu, Harris; Kim, Yoojeong; Mello, Kerrianne; Lovaasen, John; Shah, Apoorva; Rice, Norman; Yim, Jacqueline H; Pappas, Daphne; Klibanov, Alexander M

    2014-02-01

    The currently used multistep chemical synthesis for making surfaces antimicrobial by attaching to them hydrophobic polycations is replaced herein by an aerosol-assisted plasma deposition procedure. To this end, N,N-hexyl,methyl-PEI (HMPEI) is directly plasma-coated onto a glass surface. The resultant immobilized HMPEI coating has been thoroughly characterized and shown to be robust, bactericidal against Escherichia coli, and virucidal against human influenza virus.

  10. Analysis of plasma characteristics and conductive mechanism of laser assisted pulsed arc welding

    NASA Astrophysics Data System (ADS)

    Liu, Shuangyu; Chen, Shixian; Wang, Qinghua; Li, Yanqing; Zhang, Hong; Ding, Hongtao

    2017-05-01

    This study aims to investigate the arc plasma shape and the spectral characteristics during the laser assisted pulsed arc welding process. The arc plasma shape was synchronously observed using a high speed camera, and the emission spectrum of plasma was obtained by spectrometer. The well-known Boltzmann plot method and Stark broadening were used to calculate the electron temperature and density respectively. The conductive mechanism of arc ignition in laser assisted arc hybrid welding was investigated, and it was found that the plasma current moved to the arc anode under the action of electric field. Thus, a significant parabolic channel was formed between the keyhole and the wire tip. This channel became the main method of energy transformation between the arc and the molten pool. The calculation results of plasma resistivity show that the laser plasma has low resistivity as the starting point of conductive channel formation. When the laser pulse duration increases, the intensity of the plasma radiation spectrum and the plasma electron density will increase, and the electron temperature will decrease.

  11. Laser plasma formation assisted by ultraviolet pre-ionization

    SciTech Connect

    Yalin, Azer P. Dumitrache, Ciprian; Wilvert, Nick; Joshi, Sachin; Shneider, Mikhail N.

    2014-10-15

    We present experimental and modeling studies of air pre-ionization using ultraviolet (UV) laser pulses and its effect on laser breakdown of an overlapped near-infrared (NIR) pulse. Experimental studies are conducted with a 266 nm beam (fourth harmonic of Nd:YAG) for UV pre-ionization and an overlapped 1064 nm NIR beam (fundamental of Nd:YAG), both having pulse duration of ∼10 ns. Results show that the UV beam produces a pre-ionized volume which assists in breakdown of the NIR beam, leading to reduction in NIR breakdown threshold by factor of >2. Numerical modeling is performed to examine the ionization and breakdown of both beams. The modeled breakdown threshold of the NIR, including assist by pre-ionization, is in reasonable agreement with the experimental results.

  12. Study on Reaction Products in Plasma-Assisted Selective Catalytic Reduction of NOx

    NASA Astrophysics Data System (ADS)

    Yoshizawa, Hayato; Tochikubo, Fumiyoshi; Uchida, Satoshi; Watanabe, Tsuneo

    Since the gas discharge plasma easily converts NO to NO2, which can be reduced more actively in selective catalytic reduction with hydrocarbons (HC-SCR), the plasma-assisted HC-SCR is an effective method for NOx reduction from diesel engine exhaust gases. In this work, the relation between NOx removal and reaction products is investigated in plasma-assisted HC-SCR in simulated flue gas as parameters of gas composition, plasma specific energy and catalyst temperature. C2H4 is used as a hydrocarbon and commercially available Al2O3 is used as a catalyst. After the plasma treatment of simulated flue gas, HCHO and HCOOH were generated as by-products, while NO was effectively converted to NO2. These by-products were confirmed to be reactive at lower catalyst temperature than C2H4 in HC-SCR. The relation between NOx removal and reaction products suggests that HCHO and HCOOH contribute the effective NOx reduction at low catalyst temperature in plasma-assisted HC-SCR.

  13. Gliding arc plasma assisted N2O dissociation for monopropellant propulsion

    NASA Astrophysics Data System (ADS)

    Bosi, Franco J.; Dobrynin, Danil

    2017-01-01

    In this paper we address the capability of gliding arc (GA) discharges to promote plasma assisted combustion of nitrous oxide gas (N2O) for spacecraft monopropellant thruster applications. N2O is a ‘green’ propellant with interesting properties, but highly inert when used as monopropellant. Higher vibrational temperatures {{T}\\text{v}}>T , and hot spot localized dissociation, achieved within the GA reactor, are able to promote combustion of the gas. The vibrational temperature of the N2 second positive system is estimated by means of optical emission spectroscopy and reaches 5000 K, while the gas temperature reaches 1500 K the degree of N2O decomposition, estimated by FTIR measurements, ranged from 25 to 85%. A kinetic model for N2O dissociation is developed; the model shows that simply heating the gas in the same conditions is not enough to produce appreciable dissociation, providing further evidence of the catalytic action of the plasma. Results allow us to predict the propulsive efficiencies to be about 43%, with a thrust level of 37 mN; this result compares positively with the existing N2O resistojet technology.

  14. Plasma-assisted conversion of solid hydrocarbon to diamond

    DOEpatents

    Valone, Steven M.; Pattillo, Stevan G.; Trkula, Mitchell; Coates, Don M.; Shah, S. Ismat

    1996-01-01

    A process of preparing diamond, e.g., diamond fiber, by subjecting a hydrocarbon material, e.g., a hydrocarbon fiber, to a plasma treatment in a gaseous feedstream for a sufficient period of time to form diamond, e.g., a diamond fiber is disclosed. The method generally further involves pretreating the hydrocarbon material prior to treatment with the plasma by heating within an oxygen-containing atmosphere at temperatures sufficient to increase crosslinking within said hydrocarbon material, but at temperatures insufficient to melt or decompose said hydrocarbon material, followed by heating at temperatures sufficient to promote outgassing of said crosslinked hydrocarbon material, but at temperatures insufficient to convert said hydrocarbon material to carbon.

  15. Towards large-scale plasma-assisted synthesis of nanowires

    NASA Astrophysics Data System (ADS)

    Cvelbar, U.

    2011-05-01

    Large quantities of nanomaterials, e.g. nanowires (NWs), are needed to overcome the high market price of nanomaterials and make nanotechnology widely available for general public use and applications to numerous devices. Therefore, there is an enormous need for new methods or routes for synthesis of those nanostructures. Here plasma technologies for synthesis of NWs, nanotubes, nanoparticles or other nanostructures might play a key role in the near future. This paper presents a three-dimensional problem of large-scale synthesis connected with the time, quantity and quality of nanostructures. Herein, four different plasma methods for NW synthesis are presented in contrast to other methods, e.g. thermal processes, chemical vapour deposition or wet chemical processes. The pros and cons are discussed in detail for the case of two metal oxides: iron oxide and zinc oxide NWs, which are important for many applications.

  16. Laser Diagnostics Study of Plasma Assisted Combustion for Scramjet Applications

    DTIC Science & Technology

    2011-12-01

    future. The combustion process in these engines typically involves highly turbulent reactive flow conditions, often beyond the limits of our...electric field gives rise to new electron and ion impact processes which can enhance the propagation and branching of radicals and ultimately...is generated separately and the flame is ignited as the gases pass over the plasma region. The actual oxidation process occurs further downstream

  17. Kinetics in Gas Mixtures for Problem of Plasma Assisted Combustion

    DTIC Science & Technology

    2010-05-01

    exothermal chemical hydrocarbon oxidation process, and (iii) subsequent thermal ignition. The role of gas temperature increase in the experiments on...the nonequilibrium plasma, (ii) chemical reactions of hydrocarbon oxidation with participa- tion of O atoms and gas heating due to net exothermal ...autoignition) the ignition delay de- pends upon the rate of the dissociation reaction which is endothermic . Generally the induction delay time is greatly

  18. Microwave plasma assisted pyrolysis of refuse derived fuels

    NASA Astrophysics Data System (ADS)

    Khongkrapan, Parin; Thanompongchart, Patipat; Tippayawong, Nakorn; Kiatsiriroat, Tanongkiat

    2014-03-01

    This work combined plasma reactivity and pyrolysis for conversion of solid wastes. Decomposition of refuse derived fuel (RDF) and its combustible components (paper, biomass, and plastic) in an 800 W microwave plasma reactor was investigated at varying argon flow rates of 0.50 to 1.25 lpm for 3 minutes. The characteristic bright light emission of plasma was observed with calculated maximum power density of about 35 W/cm3. The RDF and its components were successfully converted into char and combustible gas. The average char yield was found to be 12-21% of the original mass, with a gross calorific value of around 39 MJ/kg. The yield of the product gas was in the range 1.0-1.7 m3/kg. The combustible gas generated from the pyrolysis of the RDF contained about 14% H2, 66% CO, and 4% CH4 of the detected gas mass, with a heating value of 11 MJ/m3. These products are potentially marketable forms of clean energy.

  19. Measurements of experimental plasma brush behavior in hybrid armatures

    NASA Astrophysics Data System (ADS)

    Hawke, R. S.; Morrison, J. J.; Susoeff, A. R.

    1993-01-01

    Hybrid armatures used in railguns, consist of a conducting link which is commutated to the rails by plasma brushes. The formation, properties and stability of plasma brushes is important to the performance of the armature. This paper describes a set of experiments in which the effects of varying plasma brush parameters including the initial mass of metal foil used to form the plasma as well as the current were studied. The evolution of the plasma brush from a solid metal foil through its melt, vapor and plasma phase were observed. The resulting brush length and voltage drop were measured. The results of these tests are presented, discussed and compared to numerical simulations.

  20. Thrust Stand Measurements of a Conical Pulsed Inductive Plasma Thruster

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley K.; Polzin, Kurt A.; Emsellem, Gregory D.

    2012-01-01

    Pulsed inductive plasma thrusters [1-3] are spacecraft propulsion devices in which electrical energy is capacitively stored and then discharged through an inductive coil. The thruster is electrodeless, with a time-varying current in the coil interacting with a plasma covering the face of the coil to induce a plasma current. Propellant is accelerated and expelled at a high exhaust velocity (O(10-100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, pulsed inductive plasma thrusters can su er from both high pulse energy requirements imposed by the voltage demands of inductive propellant ionization, and low propellant utilization efficiencies. The Microwave Assisted Discharge Inductive Plasma Accelerator (MAD-IPA)[4], shown in Fig. 1 is a pulsed inductive plasma thruster that is able to operate at lower pulse energies by partially ionizing propellant with an electron cyclotron resonance (ECR) discharge inside a conical inductive coil whose geometry serves to potentially increase propellant and plasma plume containment relative to at coil geometries. The ECR plasma is created with the use of permanent mag- nets arranged to produce a thin resonance region along the inner surface of the coil, restricting plasma formation and, in turn, current sheet formation to areas of high magnetic coupling to the driving coil.

  1. Plasma-parameter measurements using neutral-particle-beam attenuation

    SciTech Connect

    Foote, J H; Molvik, A W; Turner, W C

    1982-07-07

    Intense and energetic neutral-particle-beam injection used for fueling or heating magnetically confined, controlled-fusion experimental plasmas can also provide diagnostic measurements of the plasmas. The attenuation of an atomic beam (mainly from charge-exchange and ionization interactions) when passing through a plasma gives the plasma line density. Orthogonal arrays of highly collimated detectors of the secondary-electron-emission type have been used in magnetic-mirror experiments to measure neutral-beam attenuation along chords through the plasma volume at different radial and axial positions. The radial array is used to infer the radial plasma-density profile; the axial array, to infer the axial plasma-density profile and the ion angular distribution at the plasma midplane.

  2. Plasma potential measurement using centre tapped emissive probe (CTEP) in laboratory plasma

    NASA Astrophysics Data System (ADS)

    Sanyasi, A. K.; Srivastava, P. K.; Awasthi, L. M.

    2017-04-01

    Plasma potential measurements using a compensated center tapped emissive probe (CTEP) in quiescent plasma ({{n}\\text{e}}∼ 6.0× {{10}11} \\text{c}{{\\text{m}}-3}, {{T}\\text{e}}∼ 3.5 \\text{eV} ) of large volume plasma device (LVPD) are presented. The CTEP shows distinct advantage over conventional emissive probe (CEP) because of measurement capability, independent of electronics and operating conditions of CEP. Its ability of measuring continuous, uninterrupted plasma potential (DC and fluctuations) measurements for pulsed and DC plasma discharges gives it advantage over other configurations. Also, its push fit design allows easy replacement without realizing frequent vacuum breaks. In small sized plasma devices, CTEP design may introduce some spatial resolution error but for large plasma devices, this is negligible as voluminous data is required over large scale lengths (~few tens of cm).

  3. Effect of process parameters on the mechanical properties of carbon nitride thin films synthesized by plasma assisted pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Tabbal, M.; Mérel, P.; Chaker, M.

    We present an investigation of the effect of the process parameters, namely deposition pressure and laser intensity, on the growth and mechanical properties of carbon nitride (CNx) thin films synthesized by plasma assisted pulsed laser deposition. Deposition at high remote plasma pressure (200 mTorr) enhances both growth rate and nitrogen incorporation (up to 40 at.%), but nano-indentation measurements indicate that these films are very soft and have poor mechanical properties. At low remote plasma pressure (0.5 mTorr), the nitrogen content varies from 24 to 16 at.% with increasing laser intensity as the films become much harder and more elastic, with hardness and Young's modulus values reaching 24 GPa and 230 GPa, respectively. These effects are explained in terms of a thermalization of the laser plasma at 200 mTorr and indicate that plasma activation of nitrogen does not provide any particular benefit to the film properties when deposition is performed at high pressure. However, at low pressure, the benefit of plasma activation is evidenced through enhanced nitrogen incorporation in the films while preserving the highly energetic species in the ablation plume. Such conditions lead to the synthesis, at room temperature, of hard and elastic films having properties close to those of fullerene-like CNx.

  4. Tunable molten oxide pool assisted plasma-melter vitrification systems

    DOEpatents

    Titus, Charles H.; Cohn, Daniel R.; Surma, Jeffrey E.

    1998-01-01

    The present invention provides tunable waste conversion systems and apparatus which have the advantage of highly robust operation and which provide complete or substantially complete conversion of a wide range of waste streams into useful gas and a stable, nonleachable solid product at a single location with greatly reduced air pollution to meet air quality standards. The systems provide the capability for highly efficient conversion of waste into high quality combustible gas and for high efficiency conversion of the gas into electricity by utilizing a high efficiency gas turbine or an internal combustion engine. The solid product can be suitable for various commercial applications. Alternatively, the solid product stream, which is a safe, stable material, may be disposed of without special considerations as hazardous material. In the preferred embodiment, the arc plasma furnace and joule heated melter are formed as a fully integrated unit with a common melt pool having circuit arrangements for the simultaneous independently controllable operation of both the arc plasma and the joule heated portions of the unit without interference with one another. The preferred configuration of this embodiment of the invention utilizes two arc plasma electrodes with an elongated chamber for the molten pool such that the molten pool is capable of providing conducting paths between electrodes. The apparatus may additionally be employed with reduced use or without further use of the gases generated by the conversion process. The apparatus may be employed as a net energy or net electricity producing unit where use of an auxiliary fuel provides the required level of electricity production. Methods and apparatus for converting metals, non-glass forming waste streams and low-ash producing inorganics into a useful gas are also provided. The methods and apparatus for such conversion include the use of a molten oxide pool having predetermined electrical, thermal and physical

  5. EDITORIAL: Non-thermal plasma-assisted fuel conversion for green chemistry Non-thermal plasma-assisted fuel conversion for green chemistry

    NASA Astrophysics Data System (ADS)

    Nozaki, Tomohiro; Gutsol, Alexander

    2011-07-01

    This special issue is based on the symposium on Non-thermal Plasma Assisted Fuel Conversion for Green Chemistry, a part of the 240th ACS National Meeting & Exposition held in Boston, MA, USA, 22-26 August 2010. Historically, the Division of Fuel Chemistry of the American Chemical Society (ACS) has featured three plasma-related symposia since 2000, and has launched special issues in Catalysis Today on three occasions: 'Catalyst Preparation using Plasma Technologies', Fall Meeting, Washington DC, USA, 2000. Special issue in Catalysis Today 72 (3-4) with 12 peer-reviewed articles. 'Plasma Technology and Catalysis', Spring Meeting, New Orleans, LA, USA, 2003. Special issue in Catalysis Today 89 (1-2) with more than 30 peer-reviewed articles. 'Utilization of Greenhouse Gases II' (partly focused on plasma-related technologies), Spring Meeting, Anaheim, CA, USA, 2004. Special issue in Catalysis Today 98 (4) with 25 peer-reviewed articles. This time, selected presentations are published in this Journal of Physics D: Applied Physics special issue. An industrial material and energy conversion technology platform is established on thermochemical processes including various catalytic reactions. Existing industry-scale technology is already well established; nevertheless, further improvement in energy efficiency and material saving has been continuously demanded. Drastic reduction of CO2 emission is also drawing keen attention with increasing recognition of energy and environmental issues. Green chemistry is a rapidly growing research field, and frequently highlights renewable bioenergy, bioprocesses, solar photocatalysis of water splitting, and regeneration of CO2 into useful chemicals. We would also like to emphasize 'plasma catalysis' of hydrocarbon resources as an important part of the innovative next-generation green technologies. The peculiarity of non-thermal plasma is that it can generate reactive species almost independently of reaction temperature. Plasma

  6. LEAN NO{sub X} REDUCTION BY PLASMA ASSISTED CATA

    SciTech Connect

    Tonkyn, Russell

    2000-08-20

    The widespread use of light duty diesel engines in the United States would naturally lead to a large reduction of fuel consumption, due to their generally higher efficiency. By extension, savings in fuel consumption would decrease the total CO2 emitted from mobile sources. Although this is a desirable goal, at present a major stumbling block to increased diesel engine use is the difficulty in reducing noxious exhaust components, mainly NOx and particulates, to acceptable levels. We are studying the possibility of reducing NOx emissions through the combination of non-thermal plasma with appropriate catalysts. The broad outline of how this technique works has been worked out both experimentally and theoretically.1-3 The presently accepted model is that a non-thermal plasma in the presence of water, oxygen and hydrocarbon will efficiently convert NO to NO2, while only partially oxidizing the hydrocarbon present. Some catalysts will reduce NO2 (but not necessarily NO) i n the presence of excess oxygen if the proper hydrocarbon is present. In this paper we report results using non-thermal plasma in conjunction with a commonly available zeolite catalyst, NaY, to treat synthetic diesel exhaust. We focus on details of the heterogeneous chemistry on NaY by comparing the thermal and plasma driven chemistry. EXPERIMENT Details of our experiment have been published elsewhere, so only a brief summary is included here.4 Synthetic exhaust gas was created by blending gases from cylinders of known composition using mass flow controllers. Besides NO, the exhaust mixture included CO, CO2, propylene, water, oxygen and nitrogen. A typical mixture contained 6% oxygen, 2% water, and, unless otherwise noted, a 3:1 ratio of propylene to NOx. This corresponds to a 9:1 ratio on a C1 basis. CO and CO2 were sometimes included, but we found that their presence did not materially affect our results. For nitrogen balance experiments we omitted CO and CO2 and replaced the nitrogen bath gas with

  7. Plasma plume dynamics in magnetically assisted pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Haverkamp, J. D.; Bourham, M. A.; Du, S.; Narayan, J.

    2009-01-01

    The expansion of a laser produced plasma perpendicular to a magnetic field is studied with a quadruple Langmuir probe and a B-dot probe. In regions where the kinetic beta is less than one, we find plume deceleration and weak displacement of the magnetic field. As the plume expands into regions of weak magnetic field, plume deceleration stops and the displacement of the magnetic field is large. The diffusion time of the magnetic field lines was consistent with anomalously large resistivity driven by the presence of an instability. Electron temperatures are larger than in the field-free case due to Ohmic heating mediated by the anomalously large resistivity.

  8. RF inductive probe to measure plasma complex conductivity

    NASA Astrophysics Data System (ADS)

    Howling, Alan

    2016-09-01

    A method for measuring plasma complex electrical conductivity is described by which plasma parameters such as the electron density and the electron-neutral collision frequency can be estimated. The method relies on the measurement of the impedance of an inductive element coupled to the plasma by mutual induction. The mutual inductance due to the plasma coupling is interpreted by applying the complex image method to the plasma medium; it is determined by the plasma skin depth and the distance to the plasma. For high frequency measurements, capacitive coupling must also be accounted for as a first order correction for standing wave (transmission line) effects. It is shown that a hybrid resonant network configuration can be designed to maximize the inductive coupling and minimize the capacitive coupling.

  9. Coanda-Assisted Spray Manipulation Collar for a Commercial Plasma Spray Gun

    NASA Astrophysics Data System (ADS)

    Mabey, K.; Smith, B. L.; Whichard, G.; McKechnie, T.

    2011-06-01

    A Coanda-assisted Spray Manipulation (CSM) collar was retrofitted to a Praxair SG-100 plasma spray gun. The CSM device makes it possible to change the direction of (vector) the plasma jet and powder without moving the gun. The two-piece retrofit device replaces the standard faceplate. Two separate collars were tested: one designed for small vector angles and one for larger vector angles. It was demonstrated that the small-angle device could modify the trajectory of zirconia powder up to several degrees. Doing so could realign the plasma with the powder resulting in increased powder temperature and velocity. The large-angle device was capable of vectoring the plasma jet up to 45°. However, the powder did not vector as much. Under large-angle vectoring, the powder velocity and temperature decreased steadily with vector angle. Both devices were tested using a supersonic configuration to demonstrate that CSM is capable of vectoring supersonic plasmas.

  10. Development of a 100 kW plasma torch for plasma assisted combustion of low heating value fuels

    NASA Astrophysics Data System (ADS)

    Takali, S.; Fabry, F.; Rohani, V.; Cauneau, F.; Fulcheri, L.

    2014-11-01

    Most thermal power plants need an auxiliary power source to (i) heat-up the boiler during start up phases before reaching autonomy power and (ii) sustain combustion at low load. This supplementary power is commonly provided with high LHV fossil fuel burners which increases operational expenses and disables the use of anti-pollutant filters. A Promising alternative is under development and consists in high temperature plasma assisted AC electro-burners. In this paper, the development of a new 100 kW three phase plasma torch with graphite electrodes is detailed. This plasma torch is working at atmospheric pressure with air as plasma gas and has three-phase power supply and working at 680 Hz. The nominal air flow rate is 60 Nm3.h-1 and the outlet gas temperature is above 2 500 K. At the beginning, graphite electrodes erosion by oxidizing medium was studied and controlling parameters were identified through parametric set of experiments and tuned for optimal electrodes life time. Then, a new 3-phase plasma torch design was modelled and simulated on ANSYS platform. The characteristics of the plasma flow and its interaction with the environing elements of the torch are detailed hereafter.

  11. The thermal engineering characteristics of plasma-assisted ignition of coal

    NASA Astrophysics Data System (ADS)

    Peregudov, V. S.

    2010-06-01

    The parameters playing an important role in implementing a technology of preparing coal for combustion by subjecting it to plasma-assisted thermal—chemical treatment are considered, and their effect on the main characteristics of the obtained product is analyzed. The optimal values of such parameters are determined.

  12. Finite Larmor radius assisted velocity shear stabilization of the interchange instability in magnetized plasmas

    SciTech Connect

    Ng Sheungwah; Hassam, A.B.

    2005-06-15

    Finite Larmor radius (FLR) effects, originally shown to stabilize magnetized plasma interchange modes at short wavelength, are shown to assist velocity shear stabilization of long wavelength interchanges. It is shown that the FLR effects result in stabilization with roughly the same efficacy as the stabilization from dissipative (resistive and viscous) effects found earlier.

  13. Plasma-assisted etching of tungsten films: A quartz-crystal microbalance study

    SciTech Connect

    Fracassi, F.; Coburn, J.W.

    1988-03-01

    The plasma-assisted etching of magnetron-sputtered polycrystalline tungsten films in CF/sub 4/-H/sub 2/ and CF/sub 4/-O/sub 2/ glow discharges has been studied as a function of ion energy using quartz-crystal microbalance methods supplemented by vacuum-transfer Auger electron spectroscopy and actinometric emission spectroscopy.

  14. Measuring plasma turbulence using low coherence microwave radiation

    SciTech Connect

    Smith, D. R.

    2012-02-20

    Low coherence backscattering (LCBS) is a proposed diagnostic technique for measuring plasma turbulence and fluctuations. LCBS is an adaptation of optical coherence tomography, a biomedical imaging technique. Calculations and simulations show LCBS measurements can achieve centimeter-scale spatial resolution using low coherence microwave radiation. LCBS measurements exhibit several advantages over standard plasma turbulence measurement techniques including immunity to spurious reflections and measurement access in hollow density profiles. Also, LCBS is scalable for 1-D profile measurements and 2-D turbulence imaging.

  15. Physics and chemistry of plasma-assisted combustion.

    PubMed

    Starikovskiy, Andrey

    2015-08-13

    There are several mechanisms that affect a gas when using discharge plasma to initiate combustion or to stabilize a flame. There are two thermal mechanisms-the homogeneous and inhomogeneous heating of the gas due to 'hot' atom thermalization and vibrational and electronic energy relaxation. The homogeneous heating causes the acceleration of the chemical reactions. The inhomogeneous heating generates flow perturbations, which promote increased turbulence and mixing. Non-thermal mechanisms include the ionic wind effect (the momentum transfer from an electric field to the gas due to the space charge), ion and electron drift (which can lead to additional fluxes of active radicals in the gradient flows in the electric field) and the excitation, dissociation and ionization of the gas by e-impact, which leads to non-equilibrium radical production and changes the kinetic mechanisms of ignition and combustion. These mechanisms, either together or separately, can provide additional combustion control which is necessary for ultra-lean flames, high-speed flows, cold low-pressure conditions of high-altitude gas turbine engine relight, detonation initiation in pulsed detonation engines and distributed ignition control in homogeneous charge-compression ignition engines, among others. Despite the lack of knowledge in mechanism details, non-equilibrium plasma demonstrates great potential for controlling ultra-lean, ultra-fast, low-temperature flames and is extremely promising technology for a very wide range of applications. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  16. Physics and chemistry of plasma-assisted combustion

    PubMed Central

    Starikovskiy, Andrey

    2015-01-01

    There are several mechanisms that affect a gas when using discharge plasma to initiate combustion or to stabilize a flame. There are two thermal mechanisms—the homogeneous and inhomogeneous heating of the gas due to ‘hot’ atom thermalization and vibrational and electronic energy relaxation. The homogeneous heating causes the acceleration of the chemical reactions. The inhomogeneous heating generates flow perturbations, which promote increased turbulence and mixing. Non-thermal mechanisms include the ionic wind effect (the momentum transfer from an electric field to the gas due to the space charge), ion and electron drift (which can lead to additional fluxes of active radicals in the gradient flows in the electric field) and the excitation, dissociation and ionization of the gas by e-impact, which leads to non-equilibrium radical production and changes the kinetic mechanisms of ignition and combustion. These mechanisms, either together or separately, can provide additional combustion control which is necessary for ultra-lean flames, high-speed flows, cold low-pressure conditions of high-altitude gas turbine engine relight, detonation initiation in pulsed detonation engines and distributed ignition control in homogeneous charge-compression ignition engines, among others. Despite the lack of knowledge in mechanism details, non-equilibrium plasma demonstrates great potential for controlling ultra-lean, ultra-fast, low-temperature flames and is extremely promising technology for a very wide range of applications. PMID:26170435

  17. Sequential quadrature measurements for plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Martin-Hidalgo, Julio

    The study of the ionosphere has been very important due to its effects on terrestrial and satellite communications. This thesis presents an introduction of the ionosphere effects, its modeling and measurement methods that have been used along the history. The Sweeping Impedance Probe (SIP) has proven over the years to be a reliable method based on the radio frequency (RF) behavior of the plasma. A new SIP architecture is presented based on the latest techniques available, using a Vector Network Analyzer (VNA) detection and employing dynamic correction of errors with Correlated Double Sampling (CDS) and a reference channel. The design will be detailed showing the component selection based on their performance parameters. In this sense, several analyses have been made to ensure that the sweep rate and accuracy requirements can be met. The testing and calibration methodology is developed to further increase the final accuracy of the instrument. Lastly, the main conclusions of the project are summarized and new and exciting lines of work are presented for what is expected to be the next generation of SIP instruments.

  18. Plasma Sensor Measurements in Pulse Detonation Engines

    NASA Astrophysics Data System (ADS)

    Matlis, Eric; Marshall, Curtis; Corke, Thomas; Gogineni, Sivaram

    2014-11-01

    Measurements have been conducted in a pulse detonation and rotating detonation engine using a newly developed plasma sensor. This sensor relies on the novel approach of using an ac-driven, weakly-ionized electrical discharge as the main sensing element. The advantages of this approach include a native high bandwidth of 1 MHz without the need for electronic frequency compensation, a dual-mode capability that provides sensitivity to multiple flow parameters, including velocity, pressure, temperature, and gas-species, and a simple and robust design making it very cost effective. The sensor design is installation-compatible with conventional sensors commonly used in gas-turbine research such as the Kulite dynamic pressure sensor while providing much better longevity. Developmental work was performed in high temperature facilities that are relevant to the propulsion and high-speed research community. This includes tests performed in a J85 augmentor at full afterburner and pulse-detonation engines at the University of Cincinnati (UC) at temperatures approaching 2760°C (5000°F).

  19. Structural, electrical and optical studies of gold nanostructures formed by Ar plasma-assisted sputtering

    NASA Astrophysics Data System (ADS)

    Siegel, J.; Kvítek, O.; Slepička, P.; Náhlík, J.; Heitz, J.; Švorčík, V.

    2012-02-01

    Ultrathin gold layers with different thickness of (10-100 nm) on the glass substrate were obtained by Ar plasma-assisted sputtering. The effects of annealing on gold structures sputtered onto glass substrate were studied using AFM, SEM, UV-Vis methods and electrical measurements. Concentration of free charge carriers were determined from the measured resistance and the Hall constant measured by the Van der Pauw method. We have shown that post-deposition thermal treatment leads in significant change in surface morphology of the sputtered Au structures. Our results suggest that the annealing affects electrical properties of the Au coverage namely electrical sheet resistance, free carriers volume concentration, the saturation of which is in comparison with as-sputtered samples shifted towards thicker structures. While semi-conductive character of as-sputtered samples diminishes close to the Au structure thickness of ca 20 nm, in the case of the annealed structures zero-level saturation is achieved for the thickness of 60 nm.

  20. Plasma-assisted heterogeneous catalysis for NOx reduction in lean-burn engine exhaust

    SciTech Connect

    Penetrante, B.M.; Hsaio, M.C.; Merritt, B.T.; Vogtlin, G.E.; Wan, C.Z.; Rice, G.W.; Voss, K.E.

    1997-12-31

    This paper discusses the combination of a plasma with a catalyst to improve the reduction of NO{sub x} under lean-burn conditions. The authors have been investigating the effects of a plasma on the NO{sub x} reduction activity and temperature operating window of various catalytic materials. One of the goals is to develop a fundamental understanding of the interaction between the gas-phase plasma chemistry and the heterogeneous chemistry on the catalyst surface. The authors have observed that plasma assisted heterogeneous catalysis can facilitate NO{sub x} reduction under conditions that normally make it difficult for either the plasma or the catalyst to function by itself. By systematically varying the plasma electrode and catalyst configuration, they have been able to elucidate the process by which the plasma chemistry affects the chemical reduction of NO{sub x} on the catalyst surface. They have discovered that the main effect of the plasma is to induce the gas-phase oxidation of NO to NO{sub 21}. The reduction of NO{sub x} to N{sub 2} is then accomplished by heterogeneous reaction of O with activated hydrocarbons on the catalyst surface. The use of a plasma opens the opportunity for a new class of catalysts that are potentially more durable, more active, more selective and more sulfur-tolerant compared to conventional lean-NO{sub x} catalysts.

  1. Plasma-assisted interface engineering of boron nitride nanostructure films.

    PubMed

    Pakdel, Amir; Bando, Yoshio; Golberg, Dmitri

    2014-10-28

    Today many aspects of science and technology are progressing into the nanoscale realm where surfaces and interfaces are intrinsically important in determining properties and performances of materials and devices. One familiar phenomenon in which interfacial interactions play a major role is the wetting of solids. In this work we use a facile one-step plasma method to control the wettability of boron nitride (BN) nanostructure films via covalent chemical functionalization, while their surface morphology remains intact. By tailoring the concentration of grafted hydroxyl groups, superhydrophilic, hydrophilic, and hydrophobic patterns are created on the initially superhydrophobic BN nanosheet and nanotube films. Moreover, by introducing a gradient of the functional groups, directional liquid spreading toward increasing [OH] content is achieved on the films. The resulting insights are meant to illustrate great potentials of this method to tailor wettability of ceramic films, control liquid flow patterns for engineering applications such as microfluidics and biosensing, and improve the interfacial contact and adhesion in nanocomposite materials.

  2. Membrane-based, sedimentation-assisted plasma separator for point-of-care applications

    PubMed Central

    Liu, Changchun; Mauk, Michael; Gross, Robert; Bushman, Frederic D.; Edelstein, Paul H.; Collman, Ronald G.; Bau, Haim H.

    2014-01-01

    Often, high sensitivity, point of care, clinical tests, such as HIV viral load, require large volumes of plasma. Although centrifuges are ubiquitously used in clinical laboratories to separate plasma from whole blood, centrifugation is generally inappropriate for on-site testing. Suitable alternatives are not readily available to separate the relatively large volumes of plasma from milliliters of blood that may be needed to meet stringent limit-of-detection specifications for low abundance target molecules. We report on a simple to use, low-cost, pump-free, membrane-based, sedimentation-assisted plasma separator capable of separating a relatively large volume of plasma from undiluted whole blood within minutes. This plasma separator consists of an asymmetric, porous, polysulfone membrane housed in a disposable chamber. The separation process takes advantage of both gravitational sedimentation of blood cells and size exclusion-based filtration. The plasma separator demonstrated a “blood in-plasma out” capability, consistently extracting 275 ±33.5 μL of plasma from 1.8 mL of undiluted whole blood in less than 7 min. The device was used to separate plasma laden with HIV viruses from HIV virus-spiked whole blood with recovery efficiencies of 95.5% ± 3.5%, 88.0% ± 9.5%, and 81.5% ± 12.1% for viral loads of 35,000, 3,500 and 350 copies/mL, respectively. The separation process is self-terminating to prevent excessive hemolysis. The HIV-laden plasma was then injected into our custom-made microfluidic chip for nucleic acid Testing And Was Successfully Subjected To Reverse Transcriptase Loop mediated isothermal amplification (RT-LAMP), demonstrating that the plasma is sufficiently pure to support high efficiency nucleic acid amplification. PMID:24099566

  3. Membrane-based, sedimentation-assisted plasma separator for point-of-care applications.

    PubMed

    Liu, Changchun; Mauk, Michael; Gross, Robert; Bushman, Frederic D; Edelstein, Paul H; Collman, Ronald G; Bau, Haim H

    2013-11-05

    Often, high-sensitivity, point-of-care (POC) clinical tests, such as HIV viral load, require large volumes of plasma. Although centrifuges are ubiquitously used in clinical laboratories to separate plasma from whole blood, centrifugation is generally inappropriate for on-site testing. Suitable alternatives are not readily available to separate the relatively large volumes of plasma from milliliters of blood that may be needed to meet stringent limit-of-detection specifications for low-abundance target molecules. We report on a simple-to-use, low-cost, pump-free, membrane-based, sedimentation-assisted plasma separator capable of separating a relatively large volume of plasma from undiluted whole blood within minutes. This plasma separator consists of an asymmetric, porous, polysulfone membrane housed in a disposable chamber. The separation process takes advantage of both gravitational sedimentation of blood cells and size exclusion-based filtration. The plasma separator demonstrated a "blood in-plasma out" capability, consistently extracting 275 ± 33.5 μL of plasma from 1.8 mL of undiluted whole blood within less than 7 min. The device was used to separate plasma laden with HIV viruses from HIV virus-spiked whole blood with recovery efficiencies of 95.5% ± 3.5%, 88.0% ± 9.5%, and 81.5% ± 12.1% for viral loads of 35,000, 3500, and 350 copies/mL, respectively. The separation process is self-terminating to prevent excessive hemolysis. The HIV-laden plasma was then injected into our custom-made microfluidic chip for nucleic acid testing and was successfully subjected to reverse-transcriptase loop-mediated isothermal amplification (RT-LAMP), demonstrating that the plasma is sufficiently pure to support high-efficiency nucleic acid amplification.

  4. Plasma Diagnostics by Antenna Impedance Measurements

    NASA Technical Reports Server (NTRS)

    Swenson, C. M.; Baker, K. D.; Pound, E.; Jensen, M. D.

    1993-01-01

    The impedance of an electrically short antenna immersed in a plasma provides an excellent in situ diagnostic tool for electron density and other plasma parameters. By electrically short we mean that the wavelength of the free-space electromagnetic wave that would be excited at the driving frequency is much longer than the physical size of the antenna. Probes using this impedance technique have had a long history with sounding rockets and satellites, stretching back to the early 1960s. This active technique could provide information on composition and temperature of plasmas for comet or planetary missions. Advantages of the impedance probe technique are discussed and two classes of instruments built and flown by SDL-USU for determining electron density (the capacitance and plasma frequency probes) are described.

  5. Measurement of Ion Temperature in a Laboratory Plasma

    NASA Astrophysics Data System (ADS)

    Liu, Jiachen; Dorfman, Seth; Carter, Troy; Gekelman, Walter; Pribyl, Patrick; Bondarenko, Anton

    2014-10-01

    Alfvén waves are low-frequency oscillating waves in a magnetized plasma. These modes may play a significant role in the heating of the solar corona, solar wind turbulence, and in fast ion transport in tokamaks. Effects that arise in a hot ion plasma are of particular interest; a new plasma source has been installed in the Large Plasma Device (LAPD) at UCLA to study this regime. In the present work, the ion temperature in this new plasma is measured using the width of the Helium ion spectral line emission. A monochromator is first used to measure cold (~0.1 ev) spectral lines of a mercury lamp to account for instrumental broadening. After acquiring this calibration data, we convolve it with plasma simulation (PrismSPECT) data for a series of known ion temperatures. The result is then compared to the actual plasma measurements to obtain the plasma ion temperature. Currently, we are working to implement a matching F-number lens system to improve the resolution of the spectral line. Results of these measurements will aid future Alfvén wave research in hot ion plasmas; this research may shed light on some of the plasma physics problems mentioned above. Supported by DOE and NSF.

  6. Measurements of EEDF in recombination dominated afterglow plasma

    NASA Astrophysics Data System (ADS)

    Plasil, R.; Korolov, I.; Kotrik, T.; Varju, J.; Dohnal, P.; Donko, Z.; Bano, G.; Glosik, J.

    2009-11-01

    Electron energy distribution functions (EEDF) have been measured in decaying plasma in Flowing Afterglow Langmuir Probe (FALP) experiment. The measurements have been carried out in diffusion and recombination governed plasmas used for studies of recombination of KrD+ and H3+ ions.

  7. High-current diode with ferroelectric plasma source-assisted hollow anode

    SciTech Connect

    Vekselman, V.; Gleizer, J. Z.; Yatom, S.; Gurovich, V. Tz.; Krasik, Ya. E.

    2010-11-15

    The operation of a ferroelectric plasma source-assisted hollow anode (HA) electron source in a vacuum diode powered by an {approx}200 kV and {approx}400 ns pulsed generator was studied using time- and space-resolved laser induced fluorescence diagnostics. It was found that the plasma ion ''temperature'' in the vicinity of the HA output grid increases up to {approx}15 eV during the accelerating pulse, which is consistent with a model of the potential screening of the grid by the randomly moving ions [Phys. Plasmas 13, 073506 (2006)]. Also it was shown that the increase in the HA plasma potential up to several kilovolts because of the appearance of a noncompensated ion charge in the HA bulk plasma due to electrons fast extraction, leads to explosive emission centers being generated at the HA grid and to nonuniformity in the cross-sectional electron beam current density. Finally, the plasma prefilled mode of diode operation was studied using a simple one-dimensional model of the plasma erosion and the HA plasma electron heating by energetic ions was considered.

  8. Plasma-assisted pretreatment of wheat straw for ethanol production.

    PubMed

    Schultz-Jensen, Nadja; Kádár, Zsófia; Thomsen, Anna Belinda; Bindslev, Henrik; Leipold, Frank

    2011-10-01

    The potential of wheat straw for ethanol production after pretreatment with O(3) generated in a plasma at atmospheric pressure and room temperature followed by fermentation was investigated. We found that cellulose and hemicellulose remained unaltered after ozonisation and a subsequent washing step, while lignin was degraded up to 95% by O(3). The loss of biomass after washing could be explained by the amount of lignin degraded. The washing water of pretreated samples (0-7 h) was analyzed for potential fermentation inhibitors. Approximately 30 lignin degradation products and a number of simple carboxylic acids and phenolic compounds were found, e.g., vanillic acid, acetic acid, and formic acid. Some components had the highest concentration at the beginning of the ozonisation process (0.5, 1 h), e.g., 4-hydroxybenzladehyde, while the concentration of others increased during the entire pretreatment (0-7 h), e.g., oxalic acid and acetovanillon. Interestingly, washing had no effect on the ethanol production with pretreatment times up to 1 h. Washing improved the glucose availability with pretreatment times of more than 2 h. One hour of ozonisation was found to be optimal for the use of washed and unwashed wheat straw for ethanol production (maximum ethanol yield, 52%). O(3) cost estimations were made for the production of ethanol at standard conditions.

  9. Surface oxidation of GaN(0001): Nitrogen plasma-assisted cleaning for ultrahigh vacuum applications

    SciTech Connect

    Gangopadhyay, Subhashis; Schmidt, Thomas Kruse, Carsten; Figge, Stephan; Hommel, Detlef; Falta, Jens

    2014-09-01

    The cleaning of metal-organic vapor-phase epitaxial GaN(0001) template layers grown on sapphire has been investigated. Different procedures, performed under ultrahigh vacuum conditions, including degassing and exposure to active nitrogen from a radio frequency nitrogen plasma source have been compared. For this purpose, x-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and scanning tunneling microscopy have been employed in order to assess chemical as well as structural and morphological surface properties. Initial degassing at 600 °C under ultrahigh vacuum conditions only partially eliminates the surface contaminants. In contrast to plasma assisted nitrogen cleaning at temperatures as low as 300 °C, active-nitrogen exposure at temperatures as high as 700 °C removes the majority of oxide species from the surface. However, extended high-temperature active-nitrogen cleaning leads to severe surface roughening. Optimum results regarding both the removal of surface oxides as well as the surface structural and morphological quality have been achieved for a combination of initial low-temperature plasma-assisted cleaning, followed by a rapid nitrogen plasma-assisted cleaning at high temperature.

  10. Effect of Inductive Coil Geometry on the Thrust Efficiency of a Microwave Assisted Discharge Inductive Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley; Polzin, Kurt; Emsellem, Gregory

    2012-01-01

    Pulsed inductive plasma thrusters [1-3] are spacecraft propulsion devices in which electrical energy is capacitively stored and then discharged through an inductive coil. The thruster is electrodeless, with a time-varying current in the coil interacting with a plasma covering the face of the coil to induce a plasma current. Propellant is accelerated and expelled at a high exhaust velocity (O(10-100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, pulsed inductive plasma thrusters require high pulse energies to inductively ionize propellant. The Microwave Assisted Discharge Inductive Plasma Accelerator (MAD-IPA) [4, 5] is a pulsed inductive plasma thruster that addressees this issue by partially ionizing propellant inside a conical inductive coil via an electron cyclotron resonance (ECR) discharge. The ECR plasma is produced using microwaves and permanent magnets that are arranged to create a thin resonance region along the inner surface of the coil, restricting plasma formation, and in turn current sheet formation, to a region where the magnetic coupling between the plasma and the inductive coil is high. The use of a conical theta-pinch coil is under investigation. The conical geometry serves to provide neutral propellant containment and plasma plume focusing that is improved relative to the more common planar geometry of the Pulsed Inductive Thruster (PIT) [2, 3], however a conical coil imparts a direct radial acceleration of the current sheet that serves to rapidly decouple the propellant from the coil, limiting the direct axial electromagnetic acceleration in favor of an indirect acceleration mechanism that requires significant heating of the propellant within the volume bounded by the current sheet. In this paper, we describe thrust stand measurements performed to characterize the performance

  11. Insights into gold-catalyzed plasma-assisted CVD growth of silicon nanowires

    SciTech Connect

    Chen, Wanghua Roca i Cabarrocas, Pere

    2016-07-25

    Understanding and controlling effectively the behavior of metal catalyst droplets during the Vapor-Liquid-Solid growth of nanowires are crucial for their applications. In this work, silicon nanowires are produced by plasma-assisted Chemical Vapor Deposition using gold as a catalyst. The influence of hydrogen plasma on nanowire growth is investigated experimentally and theoretically. Interestingly, in contrast to conventional chemical vapor deposition, the growth rate of silicon nanowires shows a decrease as a function of their diameters, which is consistent with the incorporation of silicon via sidewall diffusion. We show that Ostwald ripening of catalyst droplets during nanowire growth is inhibited in the presence of a hydrogen plasma. However, when the plasma is off, the diffusion of Au atoms on the nanowire sidewall can take place. Based on this observation, we have developed a convenient method to grow silicon nanotrees.

  12. Spectroscopic measurements of plasma emission light for plasma-based acceleration experiments

    NASA Astrophysics Data System (ADS)

    Filippi, F.; Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Zigler, A.

    2016-09-01

    Advanced particle accelerators are based on the excitation of large amplitude plasma waves driven by either electron or laser beams. Future experiments scheduled at the SPARC_LAB test facility aim to demonstrate the acceleration of high brightness electron beams through the so-called resonant Plasma Wakefield Acceleration scheme in which a train of electron bunches (drivers) resonantly excites wakefields into a preformed hydrogen plasma; the last bunch (witness) injected at the proper accelerating phase gains energy from the wake. The quality of the accelerated beam depends strongly on plasma density and its distribution along the acceleration length. The measurements of plasma density of the order of 1016-1017 cm-3 can be performed with spectroscopic measurements of the plasma-emitted light. The measured density distribution for hydrogen filled capillary discharge with both Balmer alpha and Balmer beta lines and shot-to-shot variation are here reported.

  13. High electron mobility GaN grown under N-rich conditions by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Koblmueller, G.; Wu, F.; Mates, T.; Speck, J. S.; Fernandez-Garrido, S.; Calleja, E.

    2007-11-26

    An alternative approach is presented for the plasma-assisted molecular beam epitaxy of high-quality GaN. Under N-rich growth conditions, an unexpected layer-by-layer growth mode was found for a wide range of growth temperatures in the GaN thermal decomposition regime (>750 deg. C). Consequently, superior surface morphologies with roughness of less than 1 nm (rms) have been achieved. For lightly Si-doped GaN films, room-temperature electron mobilities exceeding 1100 cm{sup 2}/V s were measured, surpassing the commonly insulating nature of GaN grown under N-rich conditions at low temperature.

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

    SciTech Connect

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

    2001-06-27

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

  15. Langmuir Probe Measurements in Plasma Shadows

    SciTech Connect

    Waldmann, O.; Koch, B.; Fussmann, G.

    2006-01-15

    When immersing a target into a plasma streaming along magnetic field lines, a distinct shadow region extending over large distances is observed by the naked eye downstream of the target.In this work we present an experimental study of the effect applying Langmuir probes. In contrast to expectations, there are only marginal changes in the profiles of temperature and density behind masks that cut away about 50% of the plasma cross-section. On the other hand, the mean density is drastically reduced by an order of magnitude. First attempts to simulate the observations by solving the classical 2D diffusion equation were not successful.

  16. Process diagnostics and monitoring using the multipole resonance probe in an inhomogeneous plasma for ion-assisted deposition of optical coatings

    NASA Astrophysics Data System (ADS)

    Styrnoll, T.; Harhausen, J.; Lapke, M.; Storch, R.; Brinkmann, R. P.; Foest, R.; Ohl, A.; Awakowicz, P.

    2013-08-01

    The application of a multipole resonance probe (MRP) for diagnostic and monitoring purposes in a plasma ion-assisted deposition (PIAD) process is reported. Recently, the MRP was proposed as an economical and industry compatible plasma diagnostic device (Lapke et al 2011 Plasma Sources Sci. Technol. 20 042001). The major advantages of the MRP are its robustness against dielectric coating and its high sensitivity to measure the electron density. The PIAD process investigated is driven by the advanced plasma source (APS), which generates an ion beam in the deposition chamber for the production of high performance optical coatings. With a background neutral pressure of p0 ˜ 20 mPa the plasma expands from the source region into the recipient, leading to an inhomogeneous spatial distribution. Electron density and electron temperature vary over the distance from substrate (ne ˜ 109 cm-3 and Te,eff ˜ 2 eV) to the APS (ne ≳ 1012 cm-3 and Te,eff ˜ 20 eV) (Harhausen et al 2012 Plasma Sources Sci. Technol. 21 035012). This huge variation of the plasma parameters represents a big challenge for plasma diagnostics to operate precisely for all plasma conditions. The results obtained by the MRP are compared to those from a Langmuir probe chosen as reference diagnostics. It is demonstrated that the MRP is suited for the characterization of the PIAD plasma as well as for electron density monitoring. The latter aspect offers the possibility to develop new control schemes for complex industrial plasma environments.

  17. Measurement of the edge plasma rotation on J-TEXT tokamak.

    PubMed

    Cheng, Z F; Luo, J; Wang, Z J; Zhang, Z P; Zhang, X L; Hou, S Y; Cheng, C; Zhuang, G

    2013-07-01

    A multi-channel high resolution spectrometer was developed for the measurement of the edge plasma rotation on J-TEXT tokamak. With the design of two opposite viewing directions, the poloidal and toroidal rotations can be measured simultaneously, and velocity accuracy is up to 1 km∕s. The photon flux was enhanced by utilizing combined optical fiber. With this design, the time resolution reaches 3 ms. An assistant software "Spectra Assist" was developed for implementing the spectrometer control and data analysis automatically. A multi-channel monochromatic analyzer is designed to get the location of chosen ions simultaneously through the inversion analysis. Some preliminary experimental results about influence of plasma density, different magnetohydrodynamics behaviors, and applying of biased electrode are presented.

  18. Measurement of the edge plasma rotation on J-TEXT tokamak

    NASA Astrophysics Data System (ADS)

    Cheng, Z. F.; Luo, J.; Wang, Z. J.; Zhang, Z. P.; Zhang, X. L.; Hou, S. Y.; Cheng, C.; Zhuang, G.

    2013-07-01

    A multi-channel high resolution spectrometer was developed for the measurement of the edge plasma rotation on J-TEXT tokamak. With the design of two opposite viewing directions, the poloidal and toroidal rotations can be measured simultaneously, and velocity accuracy is up to 1 km/s. The photon flux was enhanced by utilizing combined optical fiber. With this design, the time resolution reaches 3 ms. An assistant software "Spectra Assist" was developed for implementing the spectrometer control and data analysis automatically. A multi-channel monochromatic analyzer is designed to get the location of chosen ions simultaneously through the inversion analysis. Some preliminary experimental results about influence of plasma density, different magnetohydrodynamics behaviors, and applying of biased electrode are presented.

  19. Simulation of magnetohydrodynamics turbulence with application to plasma-assisted supersonic combustion

    NASA Astrophysics Data System (ADS)

    Miki, Kenji

    Plasma assisted combustion (PAC) is a promising alternative to hold or ignite a fuel and air mixture in a supersonic environment. Efficient supersonic combustion is of primary importance for SCRAMJET technology. The advantages of PAC is the addition of large amounts of energy to specific regions of the SCRAMJET flow-field for short periods of time, and as a result accelerate the fuel/air kinetic rates to achieve a self-sustaining condition. Moreover, the promise of enhancement of fuel-air mixing by magnetohydrodynamics (MHD) flow control offers significant improvement of combustion performance. The development of a numerical tool for investigating high-temperature chemistry and plasmadynamic effects of a discharge arc is desired to gain understanding of PAC technology and the potential improvement of the operational efficiency of SCRAMJET engines. The main objective of this research is to develop a comprehensive model with the capability of modeling both high Reynolds number and high magnetic Reynolds number turbulent flow for application to supersonic combustor. The development of this model can be divided into three categories: first, the development of a self-consistent MHD numerical model capable of modeling magnetic turbulence in high magnetic Reynolds number applications. Second, the development of a gas discharge model which models the interaction of externally applied fields in conductive medium. Third, the development of models necessary for studying supersonic combustion applications with plasma-assistance such the extension of chemical kinetics models to extremely high temperature and non-equilibrium phenomenon. Finally, these models are combined and utilized to model plasma assisted combustion in a SCRAMJET. Two types of plasmas are investigated: an equilibrium electrical discharge (arc) and a non-equilibrium plasma jet. It is shown that both plasmas significantly increase the concentration of radicals such as O, OH and H, and both have positive impact

  20. Microwave plasma-assisted ignition and flameholding in premixed ethylene/air mixtures

    NASA Astrophysics Data System (ADS)

    Fuh, Che A.; Wu, Wei; Wang, Chuji

    2016-07-01

    In this study, a 2.45 GHz microwave source and a surfatron were used, coupled with a T-shaped quartz combustor, to investigate the role of a nonthermal microwave argon plasma jet on the plasma-assisted ignition and flameholding of a premixed ethylene/air mixture. A modified U-shaped plot of the minimum plasma power required for ignition versus fuel equivalence ratio was obtained, whereby the plasma power required for plasma-assisted ignition decreased with increase in fuel equivalence ratios in the range 0.2-0.6, but for fuel equivalence ratios of 0.7 and above, the plasma power required for ignition remained fairly constant throughout. It was observed that leaner fuel/air mixtures were more sensitive to heat losses to the surrounding and this sensitivity decreased with increase in the fuel equivalence ratio. Comparison with results obtained from previous studies suggested that the mixing scheme between the plasma and the premixed fuel/air mixture and the energy density of the fuel used played an important role in influencing the minimum plasma power required for ignition with the effect being more pronounced for near stoichiometric to rich fuel equivalence ratios (0.7-1.4). Flame images obtained showed a dual layered flame with an inner white core and a bluish outer layer. The images also showed an increased degree of flameholding (tethering of the flame to the combustor orifice) with increase in plasma power. The concurrency of the dual peaks in the emission intensity profiles for OH(A), CH(A), C2(d), and the rotational temperature profiles obtained via optical emission spectroscopy along with the ground state OH(X) number density profiles in the flame using cavity ringdown spectroscopy led to the proposal that the mechanism of plasma-assisted flameholding in ethylene/air flames is predominantly radical dependent with the formation of an inner radical rich flame core which enhances the ignition and stabilization of the surrounding coflow.

  1. Microwave plasma assisted chemical vapor deposition of ultra-nanocrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Huang, Wen-Shin

    Microwave plasma assisted ultra-nanocrystalline diamond film deposition was investigated using hydrogen deficient, carbon containing argon plasma chemistries with MSU-developed microwave plasma reactors. Ultra-nanocrystalline diamond film deposition on mechanically scratched silicon wafers was experimentally explored over the following input variables: (1) pressure: 60--240Torr, (2) total gas flow rate: 101--642 sccm, (3) input microwave power 732--1518W, (4) substrate temperature: 500°C--770°C, (5) deposition time: 2--48 hours, and (6) N2 impurities 5--2500 ppm. H2 concentrations were less than 9%, while CH 4 concentration was 0.17--1.85%. It was desired to grow films uniformly over 3″ diameter substrates and to minimize the grain size. Large, uniform, intense, and greenish-white discharges were sustained in contact with three inch silicon substrates over a 60--240 Torr pressure regime. At a given operating pressure, film uniformity was controlled by adjusting substrate holder geometry, substrate position, input microwave power, gas chemistries, and total gas flow rates. Film ultra-nanocrystallinity and smoothness required high purity deposition conditions. Uniform ultra-nanocrystalline films were synthesized in low leak-rate system with crystal sizes ranging from 3--30 nm. Films with 11--50 nm RMS roughness and respective thickness values of 1--23 mum were synthesized over 3″ wafers under a wide range of different deposition conditions. Film RMS roughness 7 nm was synthesized with thickness of 430 nm. Film uniformities of almost 100% were achieved over three inch silicon wafers. UV Raman and XRD characterization results indicated the presence of diamond in the synthesized films. Optical Emission Spectroscopy measurements showed that the discharge gas temperature was in excess of 2000 K. The synthesized films are uniformly smooth and the as grown ultra-nanocrystalline diamond can be used for a high frequency SAW device substrate material. IR measurements

  2. Probe technique for measurement of a plasma potential waveform

    NASA Astrophysics Data System (ADS)

    Dvořák, P.; Tkáčik, M.; Bém, J.

    2017-05-01

    A method for the measurement of plasma potential waveforms is presented that is based on measurement with a high-impedance probe and an electric model of the sheath around the probe. The method was verified and compared with methods that were previously used for measurement of the temporal development of plasma potential during an RF period of capacitive discharges. The sensitivity of the method to the values of required input parameters (mean plasma potential value, electron concentration and temperature) was analyzed and it was found that with a lower precision, the method can be used even without the knowledge of these input parameters. Finally, plasma potential waveforms were measured in a low-pressure capacitively coupled discharge. In agreement with theoretical models, the generation of higher harmonic frequencies of plasma potential and their sensitivity to electron concentration were observed.

  3. Surface reaction mechanisms during ozone and oxygen plasma assisted atomic layer deposition of aluminum oxide.

    PubMed

    Rai, Vikrant R; Vandalon, Vincent; Agarwal, Sumit

    2010-09-07

    We have elucidated the reaction mechanism and the role of the reactive intermediates in the atomic layer deposition (ALD) of aluminum oxide from trimethyl aluminum in conjunction with O(3) and an O(2) plasma. In situ attenuated total reflection Fourier transform infrared spectroscopy data show that both -OH groups and carbonates are formed on the surface during the oxidation cycle. These carbonates, once formed on the surface, are stable to prolonged O(3) exposure in the same cycle. However, in the case of plasma-assisted ALD, the carbonates decompose upon prolonged O(2) plasma exposure via a series reaction kinetics of the type, A (CH(3)) --> B (carbonates) --> C (Al(2)O(3)). The ratio of -OH groups to carbonates on the surface strongly depends on the oxidizing agent, and also the duration of the oxidation cycle in plasma-assisted ALD. However, in both O(3) and O(2) plasma cycles, carbonates are a small fraction of the total number of reactive sites compared to the hydroxyl groups.

  4. Electron density measurements in the ITER fusion plasma

    NASA Astrophysics Data System (ADS)

    Watts, Christopher; Udintsev, Victor; Andrew, Philip; Vayakis, George; Van Zeeland, Michael; Brower, David; Feder, Russell; Mukhin, Eugene; Tolstyakov, Sergey

    2013-08-01

    The operation of ITER requires high-quality estimates of the plasma electron density over multiple regions in the plasma for plasma evaluation, plasma control and machine protection purposes. Although the density regimes of ITER are not very different from those of existing tokamaks (1018-1021 m-3), the severe conditions of the fusion plasma environment present particular challenges to implementing these density diagnostics. In this paper we present an overview of the array of ITER electron density diagnostics designed to measure over the entire ITER domain: plasma core, pedestal, edge, scrape-off layer and divertor. It will focus on the challenges faced in making these measurements, and the technical solutions of the current designs.

  5. Interferometer for the measurement of plasma density

    DOEpatents

    Jacobson, Abram R.

    1980-01-01

    An interferometer which combines the advantages of a coupled cavity interferometer requiring alignment of only one light beam, and a quadrature interferometer which has the ability to track multi-fringe phase excursions unambiguously. The device utilizes a Bragg cell for generating a signal which is electronically analyzed to unambiguously determine phase modulation which is proportional to the path integral of the plasma density.

  6. Plasma actuator electron density measurement using microwave perturbation method

    SciTech Connect

    Mirhosseini, Farid; Colpitts, Bruce

    2014-07-21

    A cylindrical dielectric barrier discharge plasma under five different pressures is generated in an evacuated glass tube. This plasma volume is located at the center of a rectangular copper waveguide cavity, where the electric field is maximum for the first mode and the magnetic field is very close to zero. The microwave perturbation method is used to measure electron density and plasma frequency for these five pressures. Simulations by a commercial microwave simulator are comparable to the experimental results.

  7. Detailed plasma potential measurements in a radio-frequency expanding plasma obtained from various electrostatic probes

    SciTech Connect

    Lafleur, T.; Charles, C.; Boswell, R. W.

    2009-04-15

    On-axis plasma potential measurements have been made with an emissive probe in a low pressure (0.044 Pa) rf expanding plasma containing an ion beam. The beam is detected with a retarding field energy analyzer (RFEA), and is seen to disappear at high pressure (0.39 Pa). The emissive probe measurements are in very good agreement with corresponding measurements made with two separate RFEAs, and the results indicate that the floating potential of the strongly emitting probe gives an accurate measure of the plasma potential under the present conditions.

  8. Lamb-shift and electric field measurements in plasmas

    NASA Astrophysics Data System (ADS)

    Doveil, F.; Chérigier-Kovacic, L.; Ström, P.

    2017-01-01

    The electric field is a quantity of particular relevance in plasma physics. Indeed, its fluctuations are responsible for different macroscopic phenomena such as anomalous transport in fusion plasmas. Answering a long-standing challenge, we offer a new method to locally and non-intrusively measure weak electric fields and their fluctuations in plasmas, by means of a beam of hydrogen ions or atoms. We present measurements of the electric field in vacuum and in a plasma where Debye shielding is measured. For the first time, we have used the Lamb-shift resonance to measure oscillating electric fields around 1 GHz and observed the strong enhancement of the Lyman-α signal. The measurement is both direct and non-intrusive. This method provides sensitivity (mV cm-1) and temporal resolution (ns) that are three orders higher compared to current diagnostics. It thus allows measuring fluctuations of the electric field at scales not previously reached experimentally.

  9. Novel diagnostics of metabolic dysfunction detected in breath and plasma by selective isotope-assisted labeling.

    PubMed

    Haviland, Julia A; Tonelli, Marco; Haughey, Dermot T; Porter, Warren P; Assadi-Porter, Fariba M

    2012-08-01

    Metabolomics is the study of a unique fingerprint of small molecules present in biological systems under healthy and disease conditions. One of the major challenges in metabolomics is validation of fingerprint molecules to identify specifically perturbed pathways in metabolic aberrations. This step is crucial to the understanding of budding metabolic pathologies and the ability to identify early indicators of common diseases such as obesity, type 2 diabetes mellitus, metabolic syndrome, polycystic ovary syndrome, and cancer. We present a novel approach to diagnosing aberrations in glucose utilization including metabolic pathway switching in a disease state. We used a well-defined prenatally exposed glucocorticoid mouse model that results in adult females with metabolic dysfunction. We applied the complementary technologies of nuclear magnetic resonance spectroscopy and cavity ring-down spectroscopy to analyze serial plasma samples and real-time breath measurements following selective (13)C-isotope-assisted labeling. These platforms allowed us to trace metabolic markers in whole animals and identify key metabolic pathway switching in prenatally glucocorticoid-treated animals. Total glucose flux is significantly proportionally increased through the major oxidative pathways of glycolysis and the pentose phosphate pathway in the prenatally glucocorticoid-treated animals relative to the control animals. This novel diagnostics approach is fast, noninvasive, and sensitive for determining specific pathway utilization, and provides a direct translational application in the health care field.

  10. Synthesis and characterization of InN nanocrystals on glass substrate by plasma assisted reactive evaporation

    NASA Astrophysics Data System (ADS)

    Ganesh, V.; Alizadeh, M.; Shuhaimi, A.; Sundaram, S.; Hakim, K. M.; Goh, B. T.; Rahman, S. A.

    2017-07-01

    InN nanocrystals were grown on glass substrate by plasma assisted reactive evaporation technique and the quality was compared with InN on Si (111) substrate. Single phase InN was confirmed by X-ray diffraction and micro Raman analysis on both the substrates. Agglomerated and Hexagonal faceting nanocrystals observed by field emission scanning electron microscopy. Energy dispersive X-ray analysis shows InN nanocrystals are nearly stochiometric. Photoluminescence reveals a broad emission near bandedge at 2 .04 eV and defect band at 1.07 eV. The Hall measurement on both the substrates reveals high electron carrier concentration. These encouraging results obtained suggested that high quality single crystalline InN can be obtained on glass substrate further optimizing the growth parameters. This novel growth of InN nanocrystals on glass substrate is an important step towards the development of monolithic, high efficiency low-cost InGaN-based renewable energy sources.

  11. Controlled Growth of Conductive AlN Thin Films by Plasma-Assisted Reactive Evaporation

    NASA Astrophysics Data System (ADS)

    Alizadeh, M.; Goh, B. T.; Rahman, S. A.

    2017-07-01

    In this work, the growth of conductive AlN thin films by plasma-assisted reactive evaporation at different filament-to-substrate distances was presented and discussed. The elemental composition, surface morphology, structural, optical, and electrical properties of the films were examined by energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, grazing incidence X-ray diffraction (GIXRD), Fourier transform infrared spectroscopy (FTIR), optical measurement, and current-voltage ( I- V) characterizations. The electrical study revealed that the films are conductive, as ohmic conductivity was observed from I- V results. The GIXRD results of AlN thin films showed that by decreasing the distance, the intensity of the peak corresponding to metallic Al decreases while that of AlN increases. EDX and XPS results indicated that at shorter distances, the incorporation of N into the AlN films is enhanced. This was further confirmed by FTIR results, which showed that the incorporation of Al-N bonds in the grown AlN films was enhanced by decreasing the distance. It was shown that the optical absorption edge of the grown films shifts from the near-ultraviolet (UV) region to far-UV as the distance is decreased.

  12. Spectral Measurements of Plasma Rotation and Mass Separation in the Archimedes Plasma Mass Filter

    NASA Astrophysics Data System (ADS)

    Umstadter, K. R.; Anderegg, F.; Cluggish, B. P.; Freeman, R. L.; Gilleland, J.; Isler, R. C.; Lee, W. D.; Litvak, A.; Mavrin, V.; Miller, R. L.; Ohkawa, T.; Putvinski, S.

    2003-10-01

    The Archimedes Demonstration Unit (ADU), a full scale experiment based upon the Plasma Mass Filter^1 technology, began plasma operations early this year. The Filter is a cylindrical device with an axial magnetic field that utilizes end electrodes to generate a radial electric field in a noble gas plasma of density ˜10^18 m-3. In addition to microwave interferometry, bolometry, videography and Langmuir probe diagnostics, high-resolution and survey spectroscopy is utilized to monitor the plasma emission. This is accomplished through the use of several in-vacuum optical arrays which have collimated views parallel and perpendicular to the magnetic axis. Optical measurements are compared to other diagnostics and electrode currents. Doppler shifts, linewidths and line ratios have been measured to determine rotation speed, temperature and separation in noble gas plasmas. ^1T. Ohkawa, "Plasma Mass Filter", U.S. Patent 6,096,220, August 1, 2000.

  13. Microwave radiation measurements near the electron plasma frequency of the NASA Lewis bumpy torus plasma

    NASA Technical Reports Server (NTRS)

    Mallavarpu, R.; Roth, J. R.

    1978-01-01

    Microwave emission near the electron plasma frequency was observed, and its relation to the average electron density and the dc toroidal magnetic field was examined. The emission was detected using a spectrum analyzer and a 50 omega miniature coaxial probe. The radiation appeared as a broad amplitude peak that shifted in frequency as the plasma parameters were varied. The observed radiation scanned an average plasma density ranging from 10 million/cu cm to 8 hundred million/cu cm. A linear relation was observed betweeen the density calculated from the emission frequency and the average plasma density measured with a microwave interferometer. With the aid of a relative density profile measurement of the plasma, it was determined that the emissions occurred from the outer periphery of the plasma.

  14. Hemolysis interference in measuring fish plasma biochemical indicators.

    PubMed

    Mirghaed, Ali Taheri; Ghelichpour, Melika; Hoseini, Seyyed Morteza; Amini, Kourosh

    2017-08-01

    The present study aimed to determine hemolysis interference in measurement of plasma biochemical parameters in fish specimens. For this purpose, blood samples were harvested from 24 Huso huso juveniles. After centrifugation, each plasma sample was divided into seven portions to make seven levels of hemolysis. Hemolysis was induced by addition of different percentages of the corresponding whole blood [0 (non-hemolyzed control group), 1, 3, 5, 10, 15, and 20% of whole blood]. Albumin, total protein, calcium, phosphorus, glucose, sodium, potassium, chloride, alkaline phosphatase (ALP), aspartate transaminase (AST), and alanine transaminase (ALT) were measured in different samples. Results showed that plasma albumin, ALP, potassium, and AST significantly increased (more than 200% at the highest hemolysis level) in the hemolyzed samples. Also, plasma total protein and phosphorus showed significant elevation in the hemolyzed samples (more than 70% at the highest hemolysis level). Plasma glucose, calcium, chloride, and ALT showed narrow but significant increase in hemolyzed samples (11.8-35.2% at the highest hemolysis level). Plasma sodium showed no significant changes in the hemolyzed samples. In conclusion, the present results show that hemolysis markedly affects plasma parameters levels, which interferes with plasma results interpretation. Therefore, analysis of hemolyzed samples should be avoided or the results should be interpreted with caution. This study encourages further investigations to develop methods for omitting the effects of hemolysis by sample blanking and/or presenting correction coefficients for measurement of plasma parameters in samples with different levels of hemolysis.

  15. Plasma Sheet Velocity Measurement Techniques for the Pulsed Plasma Thruster SIMP-LEX

    NASA Technical Reports Server (NTRS)

    Nawaz, Anuscheh; Lau, Matthew

    2011-01-01

    The velocity of the first plasma sheet was determined between the electrodes of a pulsed plasma thruster using three measurement techniques: time of flight probe, high speed camera and magnetic field probe. Further, for time of flight probe and magnetic field probe, it was possible to determine the velocity distribution along the electrodes, as the plasma sheet is accelerated. The results from all three techniques are shown, and are compared for one thruster geometry.

  16. Unambiguous atomic Bell measurement assisted by multiphoton states

    NASA Astrophysics Data System (ADS)

    Torres, Juan Mauricio; Bernád, József Zsolt; Alber, Gernot

    2016-05-01

    We propose and theoretically investigate an unambiguous Bell measurement of atomic qubits assisted by multiphoton states. The atoms interact resonantly with the electromagnetic field inside two spatially separated optical cavities in a Ramsey-type interaction sequence. The qubit states are postselected by measuring the photonic states inside the resonators. We show that if one is able to project the photonic field onto two coherent states on opposite sites of phase space, an unambiguous Bell measurement can be implemented. Thus, our proposal may provide a core element for future components of quantum information technology such as a quantum repeater based on coherent multiphoton states, atomic qubits and matter-field interaction.

  17. An ultrasound-assisted digestion method for the determination of toxic element concentrations in ash samples by inductively coupled plasma optical emission spectrometry.

    PubMed

    Ilander, Aki; Väisänen, Ari

    2007-10-29

    A method of ultrasound-assisted digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) used for the determination of toxic element concentrations (arsenic, barium, cobalt, copper, lead, nickel, strontium, vanadium and zinc) in ash samples was developed. All the measurements were performed in robust plasma conditions which were tested by measuring the Mg(II) 280.270 nm/Mg(I) 285.213 nm line intensity ratios. The highest line intensity ratios were observed when a nebulizer gas flow of 0.6 L min(-1), auxiliary gas flow of 0.2 L min(-1) and plasma power of 1400 W were used for radially viewed plasma. The analysis of SRM 1633b showed that the ultrasound-assisted method developed is highly comparable with the microwave digestion method standardized by the United States Environmental Protection Agency (EPA-3052). The ultrasound-assisted digestion with a digestion solution of aqua regia and hydrofluoric acid (HF) resulted in recovery rates of over 81%. One exception is arsenic which resulted in recoveries of about 60% only; however, it could be digested with good recovery (>90%) using a digestion solution of 5 mL of water and 5 mL of aqua regia. The major advantage of the ultrasound-assisted digestion over microwave digestion is the high treatment rate (30 samples simultaneously with a sonication time of 18 min).

  18. In situ impedance measurement of microwave atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Lee, S. T.; Nam, W. J.; Lee, J. K.; Yun, G. S.

    2017-04-01

    The impedance of atmospheric pressure argon plasma jets driven by microwave frequency is determined in situ by a novel ‘two frequency method’. In the conventional method of reflection coefficient ({{S}}11) measurement, the frequency of the driving microwave power is scanned, which inevitably affects the plasma characters and leads to uncertainty in the estimated plasma impedance. In our proposed method, the frequency-scanning signal additional to the driving power is used to measure {{S}}11 over a wide frequency range, which enables accurate determination of the plasma impedance based on an equivalent circuit model. The measured resistance and reactance of the plasma increase with the driving power in agreement with the transmission line theory. Based on this in situ measurement of the plasma impedance, the net power coupled to the plasma has been determined. The overall power efficiency remains approximately unchanged around 45% for different input power levels owing to the competing effects between the impedance mismatch and the volume change of the plasma.

  19. Progress toward measuring fast atomic recombination in ultracold plasma

    NASA Astrophysics Data System (ADS)

    Lim, Michael; Willis, Lucas

    2007-06-01

    We report on progress toward measuring the time-dependent distribution of atomic energy levels populated by recombination and collisions in ultracold plasma. The plasma is produced by direct photo-ionization of rubidium atoms in a magneto-optical trap. Our primary goal is to measure the changing Rydberg atom distribution in the first microsecond after plasma creation. Although predictions have been made for system behavior in this interval, this type of measurement has been elusive. Our apparatus features fast deflector plates to prevent saturation of the multi-channel plate detector, which is one of the main technical obstacles in this effort.

  20. Electro-optic probe measurements of electric fields in plasmas.

    PubMed

    Nishiura, M; Yoshida, Z; Mushiake, T; Kawazura, Y; Osawa, R; Fujinami, K; Yano, Y; Saitoh, H; Yamasaki, M; Kashyap, A; Takahashi, N; Nakatsuka, M; Fukuyama, A

    2017-02-01

    The direct measurements of high-frequency electric fields in a plasma bring about significant advances in the physics and engineering of various waves. We have developed an electro-optic sensor system based on the Pockels effect. Since the signal is transmitted through an optical fiber, the system has high tolerance for electromagnetic noises. To demonstrate its applicability to plasma experiments, we report the first result of measurement of the ion-cyclotron wave excited in the RT-1 magnetosphere device. This study compares the results of experimental field measurements with simulation results of electric fields in plasmas.

  1. Electro-optic probe measurements of electric fields in plasmas

    NASA Astrophysics Data System (ADS)

    Nishiura, M.; Yoshida, Z.; Mushiake, T.; Kawazura, Y.; Osawa, R.; Fujinami, K.; Yano, Y.; Saitoh, H.; Yamasaki, M.; Kashyap, A.; Takahashi, N.; Nakatsuka, M.; Fukuyama, A.

    2017-02-01

    The direct measurements of high-frequency electric fields in a plasma bring about significant advances in the physics and engineering of various waves. We have developed an electro-optic sensor system based on the Pockels effect. Since the signal is transmitted through an optical fiber, the system has high tolerance for electromagnetic noises. To demonstrate its applicability to plasma experiments, we report the first result of measurement of the ion-cyclotron wave excited in the RT-1 magnetosphere device. This study compares the results of experimental field measurements with simulation results of electric fields in plasmas.

  2. Electron Temperature Measurements in an Argon/Cesium Plasma Diode.

    DTIC Science & Technology

    1987-12-01

    MEASUREMENTS IN AN ARGON /CESIUM PLASMA DIODE 5, THESIS Michael J. Ward Second Lieutenant, USAF AFIT/GEP/ENP/87D-9 DTIC ELECTE FEB 1 01988 * DEPARTMENT OF...ENP/87D-9 S ELECTRON TEMPERATURE MEASUREMENTS IN AN ARGON /CESIUM PLASMA DIODE THESIS Presented to the Faculty of the School of Engineering of the Air...GEP/ENP/87D-9 * Abstract Line intensity measurements in an argon /cesium plasma *Q diode were made at various locations within the discharge, yielding a

  3. Visible light emission measurements from a dense electrothermal launcher plasma

    NASA Astrophysics Data System (ADS)

    Hankins, O. E.; Bourham, M. A.; Earnhart, J.; Gilligan, J. G.

    1993-01-01

    Measurements of the visible light emission from dense, weakly non-ideal plasmas have been performed on the experimental electrothermal launcher device 'SIRENS'. The plasma is created by the ablation or a Lexan insulator in the source, which then flows through a cylindrical barrel which serves as the material sample. Visible light emission spectra have been observed both in-bore and from the muzzle flash or the barrel, and from the flash or the source. Due to high plasma opacity (the plasma emits as a near blackbody) and absorption by the molecular components of the vapor shield, the hotter core or the arc has been difficult to observe. Recent measurements along the axis or the device indicate time-averaged plasma temperatures in the barrel or about 1 eV for lower energy shots, which agree with experimental measurements of the average heat flux and plasma conductivity along the barrel. Measurements or visible emission from the source indicate time averaged temperatures of 1 to 2 eV which agree with the theoretical estimates derived from ablated mass measurements and calculated estimates derived from plasma conductivity measurements.

  4. Neutron Measurements In Sahand Plasma Focus

    NASA Astrophysics Data System (ADS)

    Sobhanian, S.; Mohammad, M. A.; Golalikhani, M.; Moslehi-Fard, M.; Khorram, S.

    2010-07-01

    Experimental studies of neutron emission from a Filippov type plasma focus machine is reported here for different pressures and voltages in deuterium gas. The calibration method is discussed and time integrated and time resoled neutron signals and also the angular distribution anisotropy are studied in order to clarify the most probable mechanism for neutron production. The results showing the enhancement of neutron yield in the case of some krypton admixture is also presented.

  5. A measure of satisfaction for the assisted-living industry.

    PubMed

    Gesell, S B

    2001-01-01

    A self-administered satisfaction survey instrument for the assisted-living industry was developed and validated. The survey contains 45 Likert-type items that measure residents' and family members' satisfaction with the most central aspects of housing and care. The scale covers six key service dimensions: activities, personnel, dining, apartment, facility, and management. Internal consistency tests indicate high reliability. Multiple tests of validity confirm the scale's effectiveness in measuring residents' and family members' satisfaction with the six dimensions. Overall, residents are less satisfied with assisted-living programs than their family members are, but they may feel inhibited about expressing criticism in the presence of family. A priority index highlights service areas in which performance improvement efforts should be made to obtain the greatest increases in satisfaction while making the most efficient use of limited resources. Managerial implications of the tool are discussed.

  6. Epitaxial growth of AlN films via plasma-assisted atomic layer epitaxy

    SciTech Connect

    Nepal, N.; Qadri, S. B.; Hite, J. K.; Mahadik, N. A.; Mastro, M. A.; Eddy, C. R. Jr.

    2013-08-19

    Thin AlN layers were grown at 200–650 °C by plasma assisted atomic layer epitaxy (PA-ALE) simultaneously on Si(111), sapphire (1120), and GaN/sapphire substrates. The AlN growth on Si(111) is self-limited for trimethyaluminum (TMA) pulse of length > 0.04 s, using a 10 s purge. However, the AlN nucleation on GaN/sapphire is non-uniform and has a bimodal island size distribution for TMA pulse of ≤0.03 s. The growth rate (GR) remains almost constant for T{sub g} between 300 and 400 °C indicating ALE mode at those temperatures. The GR is increased by 20% at T{sub g} = 500 °C. Spectroscopic ellipsometry (SE) measurement shows that the ALE AlN layers grown at T{sub g} ≤ 400 °C have no clear band edge related features, however, the theoretically estimated band gap of 6.2 eV was measured for AlN grown at T{sub g} ≥ 500 °C. X-ray diffraction measurements on 37 nm thick AlN films grown at optimized growth conditions (T{sub g} = 500 °C, 10 s purge, 0.06 s TMA pulse) reveal that the ALE AlN on GaN/sapphire is (0002) oriented with rocking curve full width at the half maximum (FWHM) of 670 arc sec. Epitaxial growth of crystalline AlN layers by PA-ALE at low temperatures broadens application of the material in the technologies that require large area conformal growth at low temperatures with thickness control at the atomic scale.

  7. Surface Phenomena During Plasma-Assisted Atomic Layer Etching of SiO2.

    PubMed

    Gasvoda, Ryan J; van de Steeg, Alex W; Bhowmick, Ranadeep; Hudson, Eric A; Agarwal, Sumit

    2017-09-13

    Surface phenomena during atomic layer etching (ALE) of SiO2 were studied during sequential half-cycles of plasma-assisted fluorocarbon (CFx) film deposition and Ar plasma activation of the CFx film using in situ surface infrared spectroscopy and ellipsometry. Infrared spectra of the surface after the CFx deposition half-cycle from a C4F8/Ar plasma show that an atomically thin mixing layer is formed between the deposited CFx layer and the underlying SiO2 film. Etching during the Ar plasma cycle is activated by Ar(+) bombardment of the CFx layer, which results in the simultaneous removal of surface CFx and the underlying SiO2 film. The interfacial mixing layer in ALE is atomically thin due to the low ion energy during CFx deposition, which combined with an ultrathin CFx layer ensures an etch rate of a few monolayers per cycle. In situ ellipsometry shows that for a ∼4 Å thick CFx film, ∼3-4 Å of SiO2 was etched per cycle. However, during the Ar plasma half-cycle, etching proceeds beyond complete removal of the surface CFx layer as F-containing radicals are slowly released into the plasma from the reactor walls. Buildup of CFx on reactor walls leads to a gradual increase in the etch per cycle.

  8. Microwave plasma assisted process for cleaning and deposition in future semiconductor technology

    NASA Astrophysics Data System (ADS)

    Altmannshofer, S.; Boudaden, J.; Wieland, R.; Eisele, I.; Kutter, C.

    2017-06-01

    The epitaxial growth of silicon layers is an important step in the fabrication of semiconductor devices. For conventional silicon epitaxy, high temperatures, up to 900 °C are necessary. However, in future, semiconductor technology epitaxy processes at lower temperatures are required to increase the integration density. The goal of this study was to investigate microwave plasma assisted processes for the selective removing of thin silicon oxide, the cleaning of silicon surfaces and the depositing of high quality silicon films. The main focus was to apply these processes for low temperature epitaxy. All processes, such as oxide removal, cleaning and deposition, were done in one chamber and with microwave plasma assistance. In order to remove silicon dioxide, the etching behavior of hydrogen, fluorine, and hydrogen/fluorine plasma was studied. It was shown, that with hydrogen/fluorine plasma, the best selectivity of oxide to silicon was reached. The deposition process of silicon was studied by growing μc-Si films. The process was characterized and optimized by spectral ellipsometry. After a successful characterization of all process steps, silicon epitaxy layers have been grown with in-situ removal of native oxide and in-situ surface cleaning. The temperature for all process steps was reduced below 450 °C.

  9. Theoretical modeling of the plasma-assisted catalytic growth and field emission properties of graphene sheet

    SciTech Connect

    Sharma, Suresh C.; Gupta, Neha

    2015-12-15

    A theoretical modeling for the catalyst-assisted growth of graphene sheet in the presence of plasma has been investigated. It is observed that the plasma parameters can strongly affect the growth and field emission properties of graphene sheet. The model developed accounts for the charging rate of the graphene sheet; number density of electrons, ions, and neutral atoms; various elementary processes on the surface of the catalyst nanoparticle; surface diffusion and accretion of ions; and formation of carbon-clusters and large graphene islands. In our investigation, it is found that the thickness of the graphene sheet decreases with the plasma parameters, number density of hydrogen ions and RF power, and consequently, the field emission of electrons from the graphene sheet surface increases. The time evolution of the height of graphene sheet with ion density and sticking coefficient of carbon species has also been examined. Some of our theoretical results are in compliance with the experimental observations.

  10. Measurement of acceleration in femtosecond laser-plasmas

    SciTech Connect

    Haessner, R.; Theobald, W.; Niedermeier, S.; Michelmann, K.; Feurer, T.; Schillinger, H.; Sauerbrey, R.

    1998-02-20

    Accelerations up to 4x10{sup 19} m/s{sup 2} are measured in femtosecond laser-produced plasmas at intensities of 10{sup 18} W/cm{sup 2} using the Frequency Resolved Optical Gating (FROG) technique. A high density plasma is formed by focusing an ultrashort unchirped laser pulse on a plane carbon target and part of the reflected pulse is eventually detected by a FROG autocorrelator. Radiation pressure and thermal pressure accelerate the plasma which causes a chirp in the reflected laser pulse. The retrieved phase and amplitude information reveal that the plasma motion is dominated by the large light pressure which pushes the plasma into the target. This is supported by theoretical estimates and by the results of independently measured time integrated spectra of the reflected pulse.

  11. Langmuir probe differential measurement technique in inductively coupled RF plasmas

    NASA Astrophysics Data System (ADS)

    Djermanov, I.; Djermanova, N.; Kiss'ovski, Zh; Tsankov, Ts

    2007-04-01

    A differential measurement technique has been proposed in order to reduce noise level and stray capacitance leakage usually affecting Langmuir probe data. The technique employs two identically designed and biased Langmuir probes, connected to an instrumentation amplifier. Both probes are immersed in plasma of approximately the same space potential, one of them being plasma current collecting probe, and the second one being isolated from plasma and serving as a pick-up probe, detecting leakage currents from parasitic capacitive coupling and noise. Avoiding averaging of probe current data is the main advantage of the proposed differential technique. Experiments in the plasma expansion region of inductively driven RF source are shown to achieve lower electron temperature and higher electron density as measured by conventional single Langmuir probe. Obtaining more sharpness of the "knee" on the characteristic, thus lowering the uncertainty in plasma potential is another true merit of the differential Langmuir probe technique.

  12. Optoelectronic and structural properties of InGaN nanostructures grown by plasma-assisted MOCVD

    NASA Astrophysics Data System (ADS)

    Seidlitz, Daniel; Senevirathna, M. K. I.; Abate, Y.; Hoffmann, A.; Dietz, N.

    2015-09-01

    This paper presents optoelectronic and structural layer properties of InN and InGaN epilayers grown on sapphire templates by Migration-Enhanced Plasma Assisted Metal Organic Chemical Vapor Deposition (MEPA-MOCVD). Real-time characterization techniques have been applied during the growth process to gain insight of the plasma-assisted decomposition of the nitrogen precursor and associated growth surface processes. Analyzed Plasma Emission Spectroscopy (PES) and UV Absorption Spectroscopy (UVAS) provide detection and concentrations of plasma generated active species (N*/NH*/NHx*). Various precursors have been used to assess the nitrogen-active fragments that are directed from the hollow cathode plasma tube to the growth surface. The in-situ diagnostics results are supplemented with ex-situ materials structures investigation results of nanoscale structures using Scanning Near-field Optical Microscopy (SNOM). The structural properties have been analyzed by Raman spectroscopy and Fourier transform infrared (FTIR) reflectance. The Optoelectronic and optical properties were extracted by modeling the FTIR reflectance (e.g. free carrier concentration, high frequency dielectric constant, mobility) and optical absorption spectroscopy. The correlation and comparison between the in-situ metrology results with the ex-situ nano-structural and optoelectronic layer properties provides insides into the growth mechanism on how plasma-activated nitrogen-fragments can be utilized as nitrogen precursor for group III-nitride growth. The here assessed growth process parameter focus on the temporal precursor exposure of the growth surface, the reactor pressure, substrate temperature and their effects of the properties of the InN and InGaN epilayers.

  13. Measurement of electron density and temperature in plasmas

    NASA Technical Reports Server (NTRS)

    Billman, K. W.; Rowley, P. D.; Presley, L. L.; Stallcop, J.

    1972-01-01

    Application of two laser wavelengths passing through plasma measures electron density and temperature. Function depends on determining absorption of light at two wavelengths. Nature of reaction is explained and schematic diagram of equipment is included.

  14. Design and testing of miniaturized plasma sensor for measuring hypervelocity impact plasmas.

    PubMed

    Goel, A; Tarantino, P M; Lauben, D S; Close, S

    2015-04-01

    An increasingly notable component of the space environment pertains to the impact of meteoroids and orbital debris on spacecraft and the resulting mechanical and electrical damages. Traveling at speeds of tens of km/s, when these particles, collectively referred to as hypervelocity particles, impact a satellite, they vaporize, ionize, and produce a radially expanding plasma that can generate electrically harmful radio frequency emission or serve as a trigger for electrostatic discharge. In order to measure the flux, composition, energy distribution, and temperature of ions and electrons in this plasma, a miniaturized plasma sensor has been developed for carrying out in-situ measurements in space. The sensor comprises an array of electrostatic analyzer wells split into 16 different channels, catering to different species and energy ranges in the plasma. We present results from numerical simulation based optimization of sensor geometry. A novel approach of fabricating the sensor using printed circuit boards is implemented. We also describe the test setup used for calibrating the sensor and show results demonstrating the energy band pass characteristics of the sensor. In addition to the hypervelocity impact plasmas, the plasma sensor developed can also be used to carry out measurements of ionospheric plasma, diagnostics of plasma propulsion systems, and in other space physics experiments.

  15. Design and testing of miniaturized plasma sensor for measuring hypervelocity impact plasmas

    SciTech Connect

    Goel, A. Tarantino, P. M.; Lauben, D. S.; Close, S.

    2015-04-15

    An increasingly notable component of the space environment pertains to the impact of meteoroids and orbital debris on spacecraft and the resulting mechanical and electrical damages. Traveling at speeds of tens of km/s, when these particles, collectively referred to as hypervelocity particles, impact a satellite, they vaporize, ionize, and produce a radially expanding plasma that can generate electrically harmful radio frequency emission or serve as a trigger for electrostatic discharge. In order to measure the flux, composition, energy distribution, and temperature of ions and electrons in this plasma, a miniaturized plasma sensor has been developed for carrying out in-situ measurements in space. The sensor comprises an array of electrostatic analyzer wells split into 16 different channels, catering to different species and energy ranges in the plasma. We present results from numerical simulation based optimization of sensor geometry. A novel approach of fabricating the sensor using printed circuit boards is implemented. We also describe the test setup used for calibrating the sensor and show results demonstrating the energy band pass characteristics of the sensor. In addition to the hypervelocity impact plasmas, the plasma sensor developed can also be used to carry out measurements of ionospheric plasma, diagnostics of plasma propulsion systems, and in other space physics experiments.

  16. Design and testing of miniaturized plasma sensor for measuring hypervelocity impact plasmas

    NASA Astrophysics Data System (ADS)

    Goel, A.; Tarantino, P. M.; Lauben, D. S.; Close, S.

    2015-04-01

    An increasingly notable component of the space environment pertains to the impact of meteoroids and orbital debris on spacecraft and the resulting mechanical and electrical damages. Traveling at speeds of tens of km/s, when these particles, collectively referred to as hypervelocity particles, impact a satellite, they vaporize, ionize, and produce a radially expanding plasma that can generate electrically harmful radio frequency emission or serve as a trigger for electrostatic discharge. In order to measure the flux, composition, energy distribution, and temperature of ions and electrons in this plasma, a miniaturized plasma sensor has been developed for carrying out in-situ measurements in space. The sensor comprises an array of electrostatic analyzer wells split into 16 different channels, catering to different species and energy ranges in the plasma. We present results from numerical simulation based optimization of sensor geometry. A novel approach of fabricating the sensor using printed circuit boards is implemented. We also describe the test setup used for calibrating the sensor and show results demonstrating the energy band pass characteristics of the sensor. In addition to the hypervelocity impact plasmas, the plasma sensor developed can also be used to carry out measurements of ionospheric plasma, diagnostics of plasma propulsion systems, and in other space physics experiments.

  17. Microwave engineering of plasma-assisted CVD reactors for diamond deposition.

    PubMed

    Silva, F; Hassouni, K; Bonnin, X; Gicquel, A

    2009-09-09

    The unique properties of CVD diamond make it a compelling choice for high power electronics. In order to achieve industrial use of CVD diamond, one must simultaneously obtain an excellent control of the film purity, very low defect content and a sufficiently rapid growth rate. Currently, only microwave plasma-assisted chemical vapour deposition (MPACVD) processes making use of resonant cavity systems provide enough atomic hydrogen to satisfy these requirements. We show in this paper that the use of high microwave power density (MWPD) plasmas is necessary to promote atomic hydrogen concentrations that are high enough to ensure the deposition of high purity diamond films at large growth rates. Moreover, the deposition of homogeneous films on large surfaces calls for the production of plasma with appropriate shapes and large volumes. The production of such plasmas needs generating a fairly high electric field over extended regions and requires a careful design of the MW coupling system, especially the cavity. As far as MW coupling efficiency is concerned, the presence of a plasma load represents a mismatching perturbation to the cavity. This perturbation is especially important at high MWPD where the reflected fraction of the input power may be quite high. This mismatch can lead to a pronounced heating of the reactor walls. It must therefore be taken into account from the very beginning of the reactor design. This requires the implementation of plasma modelling tools coupled to detailed electromagnetic simulations. This is discussed in section 3. We also briefly discuss the operating principles of the main commercial plasma reactors before introducing the reactor design methodology we have developed. Modelling results for a new generation of reactors developed at LIMHP, working at very high power density, will be presented. Lastly, we show that scaling up this type of reactor to lower frequencies (915 MHz) can result in high density plasmas allowing for fast and

  18. Water/O2-plasma-assisted treatment of PCL membranes for biosignal immobilization.

    PubMed

    Saşmazel, Hilal Türkoğlu; Manolache, Sorin; Gümüşderelioğlu, Menemşe

    2009-01-01

    The main purpose of this study was to obtain COOH functionalities on the surface of poly-epsilon-caprolactone (PCL) membranes using low-pressure water/O(2)-plasma-assisted treatment. PCL membranes were prepared using the solvent-casting technique. Then, low-pressure water/O(2) plasma treatments were performed in a cylindrical, capacitively coupled RF-plasma-reactor in three steps: H(2)O/O(2)-plasma treatment; in situ (oxalyl chloride vapors) gas/solid reaction to convert -OH functionalities into -COCl groups; and hydrolysis for final -COOH functionalities. Optimization of plasma modification processes was done using the DoE software program. COOH and OH functionalities on modified surfaces were detected quantitatively using the fluorescent labeling technique and an UVX 300G sensor. Chemical structural information of untreated, plasma treated and oxalyl chloride functionalized PCL membranes were acquired using pyrolysis GC/MS and ESCA analysis. High-resolution AFM images revealed that nanopatterns were more affected than micropatterns by plasma treatments. AFM images recorded with amino-functionalized tips presented increased size of the features on the surface that suggests higher density of the carboxyls on the nanotopographical elements. Low-pressure water/O(2)-plasma-treated and oxalyl chloride functionalized samples were biologically activated with insulin and/or heparin biosignal molecules using a PEO (polyoxyethylene bis amine) spacer. The success of the immobilization process was checked qualitatively by ESCA analysis. In addition, fluorescent labeling techniques were used for the quantitative determination of immobilized biomolecules. Cell-culture experiments indicated that biomolecule immobilization onto PCL scaffolds was effective on L929 cell adhesion and proliferation, especially in the presence of heparin.

  19. Note: Zeeman splitting measurements in a high-temperature plasma

    SciTech Connect

    Golingo, R. P.; Shumlak, U.; Den Hartog, D. J.

    2010-12-15

    The Zeeman effect has been used for measurement of magnetic fields in low-temperature plasma, but the diagnostic technique is difficult to implement in a high-temperature plasma. This paper describes new instrumentation and methodology for simultaneous measurement of the entire Doppler-broadened left and right circularly polarized Zeeman spectra in high-temperature plasmas. Measurements are made using spectra emitted parallel to the magnetic field by carbon impurities in high-temperature plasma. The Doppler-broadened width is much larger than the magnitude of the Zeeman splitting, thus simultaneous recording of the two circularly polarized Zeeman line profiles is key to accurate measurement of the magnetic field in the ZaP Z-pinch plasma device. Spectral data are collected along multiple chords on both sides of the symmetry axis of the plasma. This enables determination of the location of the current axis of the Z-pinch and of lower-bound estimates of the local magnetic field at specific radial locations in the plasma.

  20. Note: Zeeman splitting measurements in a high-temperature plasma.

    PubMed

    Golingo, R P; Shumlak, U; Den Hartog, D J

    2010-12-01

    The Zeeman effect has been used for measurement of magnetic fields in low-temperature plasma, but the diagnostic technique is difficult to implement in a high-temperature plasma. This paper describes new instrumentation and methodology for simultaneous measurement of the entire Doppler-broadened left and right circularly polarized Zeeman spectra in high-temperature plasmas. Measurements are made using spectra emitted parallel to the magnetic field by carbon impurities in high-temperature plasma. The Doppler-broadened width is much larger than the magnitude of the Zeeman splitting, thus simultaneous recording of the two circularly polarized Zeeman line profiles is key to accurate measurement of the magnetic field in the ZaP Z-pinch plasma device. Spectral data are collected along multiple chords on both sides of the symmetry axis of the plasma. This enables determination of the location of the current axis of the Z-pinch and of lower-bound estimates of the local magnetic field at specific radial locations in the plasma.

  1. Plasma absorption evidence via chirped pulse spectral transmission measurements

    SciTech Connect

    Jedrkiewicz, Ottavia; Minardi, Stefano; Couairon, Arnaud; Jukna, Vytautas; Selva, Marco; Di Trapani, Paolo

    2015-06-08

    This work aims at highlighting the plasma generation dynamics and absorption when a Bessel beam propagates in glass. We developed a simple diagnostics allowing us to retrieve clear indications of the formation of the plasma in the material, thanks to transmission measurements in the angular and wavelength domains. This technique featured by the use of a single chirped pulse having the role of pump and probe simultaneously leads to results showing the plasma nonlinear absorption effect on the trailing part of the pulse, thanks to the spectral-temporal correspondence in the measured signal, which is also confirmed by numerical simulations.

  2. Germanium doping of self-assembled GaN nanowires grown by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Schörmann, Jörg; Hille, Pascal; Schäfer, Markus; Müßener, Jan; Becker, Pascal; Klar, Peter J.; Hofmann, Detlev M.; Teubert, Jörg; Eickhoff, Martin; Kleine-Boymann, Matthias; Rohnke, Marcus; Mata, Maria de la; Arbiol, Jordi

    2013-09-14

    Germanium doping of GaN nanowires grown by plasma-assisted molecular beam epitaxy on Si(111) substrates is studied. Time of flight secondary ion mass spectrometry measurements reveal a constant Ge-concentration along the growth axis. A linear relationship between the applied Ge-flux and the resulting ensemble Ge-concentration with a maximum content of 3.3×10{sup 20} cm{sup −3} is extracted from energy dispersive X-ray spectroscopy measurements and confirmed by a systematic increase of the conductivity with Ge-concentration in single nanowire measurements. Photoluminescence analysis of nanowire ensembles and single nanowires reveals an exciton localization energy of 9.5 meV at the neutral Ge-donor. A Ge-related emission band at energies above 3.475 eV is found that is assigned to a Burstein-Moss shift of the excitonic emission.

  3. Germanium doping of self-assembled GaN nanowires grown by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Schörmann, Jörg; Hille, Pascal; Schäfer, Markus; Müßener, Jan; Becker, Pascal; Klar, Peter J.; Kleine-Boymann, Matthias; Rohnke, Marcus; de la Mata, Maria; Arbiol, Jordi; Hofmann, Detlev M.; Teubert, Jörg; Eickhoff, Martin

    2013-09-01

    Germanium doping of GaN nanowires grown by plasma-assisted molecular beam epitaxy on Si(111) substrates is studied. Time of flight secondary ion mass spectrometry measurements reveal a constant Ge-concentration along the growth axis. A linear relationship between the applied Ge-flux and the resulting ensemble Ge-concentration with a maximum content of 3.3×1020 cm-3 is extracted from energy dispersive X-ray spectroscopy measurements and confirmed by a systematic increase of the conductivity with Ge-concentration in single nanowire measurements. Photoluminescence analysis of nanowire ensembles and single nanowires reveals an exciton localization energy of 9.5 meV at the neutral Ge-donor. A Ge-related emission band at energies above 3.475 eV is found that is assigned to a Burstein-Moss shift of the excitonic emission.

  4. Toward Discrete Axial p- n Junction Nanowire Light-Emitting Diodes Grown by Plasma-Assisted Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Brubaker, Matt D.; Blanchard, Paul T.; Schlager, John B.; Sanders, Aric W.; Herrero, Andrew M.; Roshko, Alexana; Duff, Shannon M.; Harvey, Todd E.; Bright, Victor M.; Sanford, Norman A.; Bertness, Kris A.

    2013-05-01

    In this paper we investigate axial p- n junction GaN nanowires grown by plasma-assisted molecular beam epitaxy (MBE), with particular attention to the effect of Mg doping on the device characteristics of individual nanowire light-emitting diodes (LEDs). We observe that a significant fraction of single-nanowire LEDs produce measurable band-gap electroluminescence when a thin AlGaN electron blocking layer (EBL) is incorporated into the device structure near the junction. Similar devices with no EBL typically yield below-detection-limit electroluminescence, despite diode-like I- V characteristics and optically measured internal quantum efficiencies (IQEs) of ˜1%. I- V measurements of the p-regions in p- n junction nanowires, as well as nanowires doped with Mg only, indicate low p-type conductivity and asymmetric Schottky-like p-contacts. These observations suggest that imbalanced carrier injection from the junction and p-contact can produce significant nonradiative losses.

  5. Plasma Measurements: An Overview of Requirements and Status

    SciTech Connect

    Kenneth M. Young

    2008-01-04

    This paper introduces this special issue on plasma diagnostics for magnetic fusion devices. Its primary purpose is to relate the measurements of plasma parameters to the physics challenges to be faced on operating and planned devices, and also to identify the diagnostic techniques that are used to make these measurements. The specific physics involved in the application of the techniques will be addressed in subsequent chapters. This chapter is biased toward measurements for tokamaks because of their proximity to the burning plasma frontier, and to set the scene for the development work associated with ITER. Hence, there is some emphasis on measurements for alpha-physics studies and the needs for plasma measurements as input to actuators to control the plasma, both for optimizing the device performance and for protection of the surrounding material. The very different approach to the engineering of diagnostics for a burning plasma is considered, emphasizing the needs for new calibration ideas, reliability and hardness against, and compatibility with, radiation. New ideas take a long time to be converted into "work-horse" sophisticated diagnostics so that investment in new developments is essential for ITER, particularly for the measurement of alpha-particles.

  6. Laboratory Measurements of Dust Charging in Flowing Plasmas

    NASA Astrophysics Data System (ADS)

    Yeo, L. H.; Han, J.; Ulibarri, Z.; Wang, X.; Munsat, T.; Horanyi, M.

    2016-12-01

    The coupling of macroscopic charge carriers (dust) in plasmas to electric and magnetic fields plays a critical role in shaping the size and spatial distribution of these particles. Planetary rings, noctilucent clouds, and comets are all examples where dusty plasma effects have been suggested to explain a number of observations. In all of these environments, the charging of the dust particles plays a crucial role. Charging of dust particles in thermal plasmas has been studied both theoretically and experimentally. Here we describe a new experimental setup for the investigation of dust charging in both non-flowing and flowing plasmas, and present preliminary results. Dust particles with diameters of 100-120 μm are released via a dust dropper and exposed to plasma before being collected in a Faraday cup, where the charges of individual grains are measured. A new design in the non-flowing plasma experiment is applied to minimize sheath effects on the charge measurements at the chamber wall. Charging of dust particles in flowing plasma is carried out at the Colorado Solar Wind Experiment (CSWE) facility, which creates simulated solar wind flow with ion energies up to 1 keV. The effect of dust size, plasma composition, and flow speed will be discussed.

  7. Ion-substituted calcium phosphate coatings deposited by plasma-assisted techniques: A review.

    PubMed

    Graziani, Gabriela; Bianchi, Michele; Sassoni, Enrico; Russo, Alessandro; Marcacci, Maurilio

    2017-05-01

    One of the main critical aspects behind the failure or success of an implant resides in its ability to fast bond with the surrounding bone. To boost osseointegration, the ideal implant material should exhibit composition and structure similar to those of biological apatite. To this aim, the most common approach is to coat the implant surface with a coating of hydroxyapatite (HA), resembling the main component of mineralized tissues. However, bone apatite is a non-stoichiometric, multi-substituted poorly-crystalline apatite, containing significant amounts of foreign ions, with high biological relevance. Ion-substituted HAs can be deposited by so called "wet methods", which are however poorly reproducible and hardly industrially feasible; at the same time bioactive coatings realized by plasma assisted method, interesting for industrial applications, are generally made of stoichiometric (i.e. un-substituted) HA. In this work, the literature concerning plasma-assisted deposition methods used to deposit ion-substituted HA was reviewed and the last advances in this field discussed. The ions taken into exam are those present in mineralized tissues and possibly having biological relevance. Notably, literature about this topic is scarce, especially relating to in vivo animal and clinical trials; further on, available studies evaluate the performance of substituted coatings from different points of view (mechanical properties, bone growth, coating dissolution, etc.) which hinders a proper evaluation of the real efficacy of ion-doped HA in promoting bone regeneration, compared to stoichiometric HA. Moreover, results obtained for plasma sprayed coatings (which is the only method currently employed for deposition at the industrial scale) were collected and compared to those of novel plasma-assisted techniques, that are expected to overcome its limitations. Data so far available on the topic were discussed to highlight advantages, limitations and possible perspectives of these

  8. Singletip Langmuir Measurements of UW-RWM Plasma

    NASA Astrophysics Data System (ADS)

    Hannum, David; Forest, C. B.; Kendrick, R.

    2008-11-01

    The rotating wall machine is a linear screw-pinch built to study the role of different wall boundary conditions on the resistive wall mode (RWM). Its plasma is created by a hexagonal array of electrostatic guns. The central seven guns can be biased to discharge up to 1 kA of current each. The 20 cm diameter, 1.2 m long plasma column is held in place by a 600 G (max) axial guide field. A singletip Langmuir probe inserted from the opposite end of the chamber yields measurements of Te, ne and Vp in r and z. Several multivariable fitting routines are employed on the I-V curve to derive the standard measurements. I will present 2D Langmuir profiles of the unbiased plasma column in several density and field configurations; biased plasma current measurements are an ongoing concern.

  9. Langmuir-probe measurements in flowing-afterglow plasmas

    SciTech Connect

    Johnsen, R.; Shun'ko, E.V.; Gougousi, T. ); Golde, M.F. )

    1994-11-01

    The validity of the orbital-motion theory for cylindrical Langmuir probes immersed in flowing-afterglow plasmas is investigated experimentally. It is found that the probe currents scale linearly with probe area only for electron-collecting but not for ion-collecting probes. In general, no agreement is found between the ion and electron densities derived from the probe currents. Measurements in recombining plasmas support the conclusion that only the [ital electron] densities derived from probe measurements can be trusted to be of acceptable accuracy. This paper also includes a brief derivation of the orbital-motion theory, a discussion of perturbations of the plasma by the probe current, and the interpretation of plasma velocities obtained from probe measurements.

  10. Langmuir-Probe Measurements in Flowing-Afterglow Plasmas

    NASA Technical Reports Server (NTRS)

    Johnsen, R.; Shunko, E. V.; Gougousi, T.; Golde, M. F.

    1994-01-01

    The validity of the orbital-motion theory for cylindrical Langmuir probes immersed in flowing- afterglow plasmas is investigated experimentally. It is found that the probe currents scale linearly with probe area only for electron-collecting but not for ion-collecting probes. In general, no agreement is found between the ion and electron densities derived from the probe currents. Measurements in recombining plasmas support the conclusion that only the electron densities derived from probe measurements can be trusted to be of acceptable accuracy. This paper also includes a brief derivation of the orbital-motion theory, a discussion of perturbations of the plasma by the probe current, and the interpretation of plasma velocities obtained from probe measurements.

  11. Langmuir-probe measurements in flowing-afterglow plasmas

    NASA Astrophysics Data System (ADS)

    Johnsen, R.; Shun'ko, E. V.; Gougousi, T.; Golde, M. F.

    1994-11-01

    The validity of the orbital-motion theory for cylindrical Langmuir probes immersed in flowing-afterglow plasmas is investigated experimentally. It is found that the probe currents scale linearly with probe area only for electron-collecting but not for ion-collecting probes. In general, no agreement is found between the ion and electron densities derived from the probe currents. Measurements in recombining plasmas support the conclusion that only the electron densities derived from probe measurements can be trusted to be of acceptable accuracy. This paper also includes a brief derivation of the orbital-motion theory, a discussion of perturbations of the plasma by the probe current, and the interpretation of plasma velocities obtained from probe measurements.

  12. A high sensitivity momentum flux measuring instrument for plasma thruster exhausts and diffusive plasmas

    SciTech Connect

    West, Michael D.; Charles, Christine; Boswell, Rod W.

    2009-05-15

    A high sensitivity momentum flux measuring instrument based on a compound pendulum has been developed for use with electric propulsion devices and radio frequency driven plasmas. A laser displacement system, which builds upon techniques used by the materials science community for surface stress measurements, is used to measure with high sensitivity the displacement of a target plate placed in a plasma thruster exhaust. The instrument has been installed inside a vacuum chamber and calibrated via two different methods and is able to measure forces in the range of 0.02-0.5 mN with a resolution of 15 {mu}N. Measurements have been made of the force produced from the cold gas flow and with a discharge ignited using argon propellant. The plasma is generated using a Helicon Double Layer Thruster prototype. The instrument target is placed about 1 mean free path for ion-neutral charge exchange collisions downstream of the thruster exit. At this position, the plasma consists of a low density ion beam (10%) and a much larger downstream component (90%). The results are in good agreement with those determined from the plasma parameters measured with diagnostic probes. Measurements at various flow rates show that variations in ion beam velocity and plasma density and the resulting momentum flux can be measured with this instrument. The instrument target is a simple, low cost device, and since the laser displacement system used is located outside the vacuum chamber, the measurement technique is free from radio frequency interference and thermal effects. It could be used to measure the thrust in the exhaust of other electric propulsion devices and the momentum flux of ion beams formed by expanding plasmas or fusion experiments.

  13. A high sensitivity momentum flux measuring instrument for plasma thruster exhausts and diffusive plasmas.

    PubMed

    West, Michael D; Charles, Christine; Boswell, Rod W

    2009-05-01

    A high sensitivity momentum flux measuring instrument based on a compound pendulum has been developed for use with electric propulsion devices and radio frequency driven plasmas. A laser displacement system, which builds upon techniques used by the materials science community for surface stress measurements, is used to measure with high sensitivity the displacement of a target plate placed in a plasma thruster exhaust. The instrument has been installed inside a vacuum chamber and calibrated via two different methods and is able to measure forces in the range of 0.02-0.5 mN with a resolution of 15 microN. Measurements have been made of the force produced from the cold gas flow and with a discharge ignited using argon propellant. The plasma is generated using a Helicon Double Layer Thruster prototype. The instrument target is placed about 1 mean free path for ion-neutral charge exchange collisions downstream of the thruster exit. At this position, the plasma consists of a low density ion beam (10%) and a much larger downstream component (90%). The results are in good agreement with those determined from the plasma parameters measured with diagnostic probes. Measurements at various flow rates show that variations in ion beam velocity and plasma density and the resulting momentum flux can be measured with this instrument. The instrument target is a simple, low cost device, and since the laser displacement system used is located outside the vacuum chamber, the measurement technique is free from radio frequency interference and thermal effects. It could be used to measure the thrust in the exhaust of other electric propulsion devices and the momentum flux of ion beams formed by expanding plasmas or fusion experiments.

  14. Plasma-assisted cleaning by metastable-atom neutralization (PACMAN): a plasma approach to cleanliness in lithography

    NASA Astrophysics Data System (ADS)

    Lytle, W. M.; Andruczyk, D.; Jindal, V.; Ruzic, D. N.

    2011-04-01

    The Plasma-Assisted Cleaning by Metastable-Atom Neutralization (PACMAN) cleaning technique being developed in the Center for Plasma-Material Interactions (CPMI) at the University of Illinois at Urbana-Champaign is a dry-non-contact vacuum-based removal technique. The PACMAN process uses a high density helium plasma (ne ~ 1017m-3, Te ~ 3eV) to achieve removal of organic contaminants on optical masks, EUV masks, silicon wafers, and optics material used in integrated circuit manufacturing. The PACMAN process is successful at removing both hydrocarbon particles as well as carbon layers by utilizing the high-energy helium metastables in the plasma. The helium metastables, with 20eV of energy, are used to break the bonds of the particle allowing for volatilization or desorption of the atoms/hydrocarbon chains of the particle to achieve an etching-like removal method without using traditional etchant process gasses. With ion energies of 10eV, damage such as surface roughening or surface erosion to the underlying structures being cleaned are avoided. Also, film densification (the removal of hydrogen from a hydrocarbon resulting in a dense carbon layer at the surface of the particle) is avoided in the PACMAN technique due to the absence of high-energy ions which would preferentially sputter hydrogen out of the particle matrix. Preliminary results for the removal of polystyrene latex nanoparticles in the range of 30 nm to 500 nm have shown removal rates of 1.2x107 +/- 5.1x105 nm3/min without damage to silicon wafers. Also, carbon films on silicon wafers have been removed with the PACMAN technique at a rate of 3.0x106 +/- 1.3x105 nm3/min. Current results of cleaning various particle types from surfaces through the PACMAN process will be presented in addition to a theoretical model of the removal process.

  15. Plasma detector for TEA CO2 laser pulse measurement

    NASA Astrophysics Data System (ADS)

    Ichikawa, Y.; Yamanaka, M.; Mitsuishi, A.; Fujita, S.; Yamanaka, T.; Yamanaka, C.; Tsunawaki, Y.; Iwasaki, T.; Takai, M.

    1983-10-01

    Laser-pulse evolution can be detected by measuring the emf generated by fast electrons in a laser-produced plasma when the laser radiation is focused onto a solid metal target in a vacuum. Using this phenomenon a 'plasma detector' is constructed, and its characteristics for the TEA CO2 laser radiation of intensity 10 to the 9th to 10 to the 10th W/sq cm are investigated experimentally. The plasma detector operates at room temperature and is strong against laser damages. For the evacuated plasma detector down to 0.1 torr, a maximum output voltage of 90 V and a rise time shorter than 1 ns are observed. The plasma detector, therefore, can be used as a power monitor for laser pulses and as a trigger voltage source.

  16. How plasma parameters fluctuations influence emissive probe measurements

    SciTech Connect

    Bousselin, G. Plihon, N.; Lemoine, N.; Heuraux, S.; Cavalier, J.

    2015-05-15

    Relationship between the floating potential of an emissive probe and plasma potential oscillations is studied in the case of controlled oscillations of plasma parameters. This relationship is compared to a quasi-static model for floating potential oscillations that assumes a constant emission current and includes the fluctuations of plasma parameters (density and electron temperature). Two different plasma regimes are considered. In the first one, the model is coherent with experimental results. In the second, the model does not fulfill one of the assumption due to the evidence of emission current oscillations when the mean emission current exceeds a given threshold. This second regime highlights the importance of taking into account emission current oscillations in the interpretation of emissive probe measurements. Nevertheless, discrepancies are still observed between emissive probe floating potential and plasma potential oscillations.

  17. Impact of anomalous dispersion on the interferometer measurements of plasmas

    SciTech Connect

    Nilsen, J; Johnson, W R; Iglesias, C A; Scofield, J H

    2004-12-16

    For many decades optical interferometers have been used to measure the electron density of plasmas. During the last ten years X-ray lasers in the wavelength range 14 to 47 nm have enabled researchers to use interferometers to probe even higher density plasmas. The data analysis assumes that the index of refraction is due only to the free electrons, which makes the index of refraction less than one and the electron density proportional to the number of fringe shifts. Recent experiments in Al plasmas observed plasmas with an index of refraction greater than one and made us question the validity of the usual formula for calculating the index of refraction. Recent calculations showed how the anomalous dispersion from the bound electrons can dominate the index of refraction in many types of plasma and make the index greater than one or enhance the index such that one would greatly overestimate the electron density of the plasma using interferometers. In this work we calculate the index of refraction of C, Al, Ti, and Pd plasmas for photon energies from 0 to 100 eV (12.4 nm) using a new average-atom code. The results show large variations from the free electron approximation under many different plasma conditions. We validate the average-atom code against the more detailed OPAL code for carbon and aluminum plasmas. During the next decade X-ray free electron lasers and other sources will be available to probe a wider variety of plasmas at higher densities and shorter wavelengths so understanding the index of refraction in plasmas will be even more essential.

  18. Measurement of parallel ion energy distribution function in PISCES plasma

    SciTech Connect

    Tynan, G.R.; Goebel, D.M.; Conn, R.W.

    1987-08-01

    The PISCES facility is used to conduct controlled plasma-surface interaction experiments. Plasma parameters typical of those found in the edge plasmas of major fusion confinement experiments are produced. In this work, the energy distribution of the ion flux incident on a material surface is measured using a gridded energy analyzer in place of a material sample. The full width at half maximum energy distribution of the ion flux is found to vary from 10 eV to 30 eV both hydrogen and deuterium plasmas. Helium plasmas have a much lower FWHM energy spread than hydrogen and deuterium plasmas. The FWHM ion energy spread is found to be linearly related to the electron temperature. The most probable ion energy is found to be linearly related to the bias applied to the energy analyzer. Other plasma parameters have a weak influence upon the energy distribution of the ion flux. Two possible physical mechanisms for producing the observed results are introduced and suggestions for further work are made. The impact of the reported measurements on the materials experiments conducted in the PISCES facility are discussed and recommendations for future experiments are made. 11 refs., 13 figs.

  19. Plasma-assisted atomic layer deposition of Al{sub 2}O{sub 3} moisture permeation barriers on polymers

    SciTech Connect

    Langereis, E.; Creatore, M.; Heil, S. B. S.; Sanden, M. C. M. van de; Kessels, W. M. M.

    2006-08-21

    Thin Al{sub 2}O{sub 3} films of different thicknesses (10-40 nm) were deposited by plasma-assisted atomic layer deposition on substrates of poly(2,6-ethylenenaphthalate) (PEN), and the water vapor transmission rate (WVTR) values were measured by means of the calcium test. The permeation barrier properties improved with decreasing substrate temperature and a good WVTR of 5x10{sup -3} g m{sup -2} day{sup -1} (WVTR{sub PEN}=0.5 g m{sup -2} day{sup -1}) was measured for a 20 nm thick Al{sub 2}O{sub 3} film deposited at room temperature using short purging times. Such ultrathin, low-temperature deposited, high-quality moisture permeation barriers are an essential requirement for the implementation of polymeric substrates in flexible electronic and display applications.

  20. Opacity measurements in shock-generated argon plasmas

    SciTech Connect

    Erskine, D.

    1993-07-01

    Dense plasmas having uniform and constant density and temperature are generated by passage of a planar shock wave through gas. The opacity of the plasma is accurately measured versus wavelength by recording the risetime of emitted light. This technique is applicable to a wide variety of species and plasma conditions. Initial experiments in argon have produced plasmas with 2 eV temperatures, 0.004--0.04 g/cm{sup 3} densities, and coupling parameters {Gamma} {approximately}0.3--0.7. Measurements in visible light are compared with calculations using the HOPE code. An interesting peak in the capacity at 400 nm is observed for the first time and is identified with the 4s-5p transition in excited neutral argon atoms.

  1. Measurements of the Jovian plasma sheet thickness from magnetometer data

    NASA Astrophysics Data System (ADS)

    Hanlon, P. G.; Dougherty, M. K.

    The Jovian middle magnetosphere is dominated by the presence of an equatorial current carrying plasma sheet. Beyond distances of approximately 20-30 Jupiter radii the plasma sheet decouples from the magnetic equatorial plane. This is due to the offset planetary dipole, the significant Alfvén wave transit time from the ionosphere to the equatorial plane and solar wind forcing. The overall time-dependant topology of the plasma sheet is therefore complex and has been modelled by previous authors [Khurana, 1992; Khurana, 2003]. Here we present survey results of measurements of the current sheet thickness from magnetometer data.

  2. Controlling the defects and transition layer in SiO2 films grown on 4H-SiC via direct plasma-assisted oxidation

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Kyoung; Jeong, Kwang-Sik; Kang, Yu-Seon; Kang, Hang-Kyu; Cho, Sang W.; Kim, Sang-Ok; Suh, Dongchan; Kim, Sunjung; Cho, Mann-Ho

    2016-10-01

    The structural stability and electrical performance of SiO2 grown on SiC via direct plasma-assisted oxidation were investigated. To investigate the changes in the electronic structure and electrical characteristics caused by the interfacial reaction between the SiO2 film (thickness ~5 nm) and SiC, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), density functional theory (DFT) calculations, and electrical measurements were performed. The SiO2 films grown via direct plasma-assisted oxidation at room temperature for 300s exhibited significantly decreased concentrations of silicon oxycarbides (SiOxCy) in the transition layer compared to that of conventionally grown (i.e., thermally grown) SiO2 films. Moreover, the plasma-assisted SiO2 films exhibited enhanced electrical characteristics, such as reduced frequency dispersion, hysteresis, and interface trap density (Dit ≈ 1011 cm‑2 · eV‑1). In particular, stress induced leakage current (SILC) characteristics showed that the generation of defect states can be dramatically suppressed in metal oxide semiconductor (MOS) structures with plasma-assisted oxide layer due to the formation of stable Si-O bonds and the reduced concentrations of SiOxCy species defect states in the transition layer. That is, energetically stable interfacial states of high quality SiO2 on SiC can be obtained by the controlling the formation of SiOxCy through the highly reactive direct plasma-assisted oxidation process.

  3. Controlling the defects and transition layer in SiO2 films grown on 4H-SiC via direct plasma-assisted oxidation

    PubMed Central

    Kim, Dae-Kyoung; Jeong, Kwang-Sik; Kang, Yu-Seon; Kang, Hang-Kyu; Cho, Sang W.; Kim, Sang-Ok; Suh, Dongchan; Kim, Sunjung; Cho, Mann-Ho

    2016-01-01

    The structural stability and electrical performance of SiO2 grown on SiC via direct plasma-assisted oxidation were investigated. To investigate the changes in the electronic structure and electrical characteristics caused by the interfacial reaction between the SiO2 film (thickness ~5 nm) and SiC, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), density functional theory (DFT) calculations, and electrical measurements were performed. The SiO2 films grown via direct plasma-assisted oxidation at room temperature for 300s exhibited significantly decreased concentrations of silicon oxycarbides (SiOxCy) in the transition layer compared to that of conventionally grown (i.e., thermally grown) SiO2 films. Moreover, the plasma-assisted SiO2 films exhibited enhanced electrical characteristics, such as reduced frequency dispersion, hysteresis, and interface trap density (Dit ≈ 1011 cm−2 · eV−1). In particular, stress induced leakage current (SILC) characteristics showed that the generation of defect states can be dramatically suppressed in metal oxide semiconductor (MOS) structures with plasma-assisted oxide layer due to the formation of stable Si-O bonds and the reduced concentrations of SiOxCy species defect states in the transition layer. That is, energetically stable interfacial states of high quality SiO2 on SiC can be obtained by the controlling the formation of SiOxCy through the highly reactive direct plasma-assisted oxidation process. PMID:27721493

  4. Measurement and control of plasma oscillations in femtosecond filaments.

    PubMed

    Zhou, B; Houard, A; Liu, Y; Prade, B; Mysyrowicz, A; Couairon, A; Mora, P; Smeenk, C; Arissian, L; Corkum, P

    2011-06-24

    The short-lived longitudinal plasma oscillations generated during filamentation in argon and nitrogen gas are measured with a specially designed current monitor. The magnitude and initial direction of the corresponding currents depend sensitively on laser polarization and nature of the gas. The results are interpreted as resulting from the competition between two forces acting on free electrons born during the filamentation process: the Lorentz laser force and a Coulomb wake force resulting from a lateral expansion of the plasma.

  5. Measurement and Control of Plasma Oscillations in Femtosecond Filaments

    SciTech Connect

    Zhou, B.; Houard, A.; Liu, Y.; Prade, B.; Mysyrowicz, A.; Couairon, A.; Mora, P.; Smeenk, C.; Arissian, L.; Corkum, P.

    2011-06-24

    The short-lived longitudinal plasma oscillations generated during filamentation in argon and nitrogen gas are measured with a specially designed current monitor. The magnitude and initial direction of the corresponding currents depend sensitively on laser polarization and nature of the gas. The results are interpreted as resulting from the competition between two forces acting on free electrons born during the filamentation process: the Lorentz laser force and a Coulomb wake force resulting from a lateral expansion of the plasma.

  6. Spectroscopic Measurements of Collision-less Coupling Between Explosive Debris Plasmas and Ambient, Magnetized Background Plasmas

    NASA Astrophysics Data System (ADS)

    Bondarenko, Anton; Schaeffer, Derek; Everson, Erik; Vincena, Stephen; van Compernolle, Bart; Constantin, Carmen; Clark, Eric; Niemann, Christoph

    2013-10-01

    Emission spectroscopy is currently being utilized in order to assess collision-less momentum and energy coupling between explosive debris plasmas and ambient, magnetized background plasmas of astrophysical relevance. In recent campaigns on the Large Plasma Device (LAPD) (nelec =1012 -1013 cm-3, Telec ~ 5 eV, B0 = 200 - 400 G) utilizing the new Raptor laser facility (1053 nm, 100 J per pulse, 25 ns FWHM), laser-ablated carbon debris plasmas were generated within ambient, magnetized helium background plasmas and prominent spectral lines of carbon and helium ions were studied in high spectral (0 . 01 nm) and temporal (50 ns) resolution. Time-resolved velocity components extracted from Doppler shift measurements of the C+4 227 . 1 nm spectral line along two perpendicular axes reveal significant deceleration as the ions stream and gyrate within the helium background plasma, indicating collision-less momentum coupling. The He+1 320 . 3 nm and 468 . 6 nm spectral lines of the helium background plasma are observed to broaden and intensify in response to the carbon debris plasma, indicative of strong electric fields (Stark broadening) and energetic electrons. The experimental results are compared to 2D hybrid code simulations.

  7. A small spacecraft for multipoint measurement of ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Roberts, T. M.; Lynch, K. A.; Clayton, R. E.; Weiss, J.; Hampton, D. L.

    2017-07-01

    Measurement of ionospheric plasma is often performed by a single in situ device or remotely using cameras and radar. This article describes a small, low-resource, deployed spacecraft used as part of a local, multipoint measurement network. A B-field aligned sounding rocket ejects four of these spin-stabilized spacecraft in a cross pattern. In this application, each spacecraft carries two retarding potential analyzers which are used to determine plasma density, flow, and ion temperature. An inertial measurement unit and a light-emitting diode array are used to determine the position and orientation of the devices after deployment. The design of this spacecraft is first described, and then results from a recent test flight are discussed. This flight demonstrated the successful operation of the deployment mechanism and telemetry systems, provided some preliminary plasma measurements in a simple mid-latitude environment, and revealed several design issues.

  8. Laboratory measurements of the resistivity of warm dense plasmas

    NASA Astrophysics Data System (ADS)

    Booth, Nicola; Robinson, Alex; Hakel, Peter; Gregori, Ginaluca; Rajeev, Pattathil; Woolsey, Nigel

    2015-11-01

    In this talk we will present a method for studying material resistivity in warm dense plasmas in the laboratory in which we interrogate the microphysics of the low energy electron distributions associated with an anisotropic return current. Through experimental measurements of the polarization of the Ly- α doublet emission (2s1 / 2-2p1 / 2,3/2 transitions) of sulphur, we determine the resistivity of a sulphur-doped plastic target heated to warm dense conditions by an ultra-intense laser at relativistic intensities, I ~ 5 ×1020 Wcm-2. We describe a method of exploiting classical x-ray scattering to separately measure both the π- and σ- polarizations of Ly-α1 spectral emission in a single shot. These measurements make it possible to explore fundamental material properties such as resistivity in warm and hot dense plasmas through matching plasma physics modelling to atomic physics calculations of the experimentally measured large, positive, polarisation.

  9. Measurement of plasma homovanillic acid concentrations in schizophrenic patients.

    PubMed

    Kaminski, R; Powchick, P; Warne, P A; Goldstein, M; McQueeney, R T; Davidson, M

    1990-01-01

    1. Several lines of evidence suggest that abnormalities of central dopaminergic transmission may be involved in the expression of some schizophrenic symptoms. However, elucidation of the role of dopamine (DA) in schizophrenia has eluded investigative efforts partially because no accurate and easily repeatable measure of brain DA activity exists. 2. The development of a technique to measure homovanillic acid in plasma has offered the possibility of performing serial measurements of this major DA metabolite. 3. Assuming that plasma homovanillic acid (PHVA) concentrations is an index of brain DA activity, measurement of PHVA can play a role in elucidating the DA abnormality in schizophrenia. 4. Results to date suggest that plasma homovanillic acid concentrations are lower in chronic schizophrenic patients compared to normal controls, and that PHVA values correlate with schizophrenic symptom severity. 5. In addition, PHVA levels were shown to initially rise and subsequently decline during chronic neuroleptic administration in treatment responsive but not in treatment refractory schizophrenic patients.

  10. Impact of plasma noise on a direct thrust measurement system.

    PubMed

    Pottinger, S J; Lamprou, D; Knoll, A K; Lappas, V J

    2012-03-01

    In order to evaluate the accuracy and sensitivity of a pendulum-type thrust measurement system, a linear variable differential transformer (LVDT) and a laser optical displacement sensor have been used simultaneously to determine the displacement resulting from an applied thrust. The LVDT sensor uses an analog interface, whereas the laser sensor uses a digital interface to communicate the displacement readings to the data acquisition equipment. The data collected by both sensors show good agreement for static mass calibrations and validation with a cold gas thruster. However, the data obtained using the LVDT deviate significantly from that of the laser sensor when operating two varieties of plasma thrusters: a radio frequency (RF) driven plasma thruster, and a DC powered plasma thruster. Results establish that even with appropriate shielding and signal filtering the LVDT sensor is subject to plasma noise and radio frequency interactions which result in anomalous thrust readings. Experimental data show that the thrust determined using the LVDT system in a direct current plasma environment and a RF discharge is approximately a factor of three higher than the thrust values obtained using a laser sensor system for the operating conditions investigated. These findings are of significance to the electric propulsion community as LVDT sensors are often utilized in thrust measurement systems and accurate thrust measurement and the reproducibility of thrust data is key to analyzing thruster performance. Methods are proposed to evaluate system susceptibility to plasma noise and an effective filtering scheme presented for DC discharges.

  11. Impact of plasma noise on a direct thrust measurement system

    NASA Astrophysics Data System (ADS)

    Pottinger, S. J.; Lamprou, D.; Knoll, A. K.; Lappas, V. J.

    2012-03-01

    In order to evaluate the accuracy and sensitivity of a pendulum-type thrust measurement system, a linear variable differential transformer (LVDT) and a laser optical displacement sensor have been used simultaneously to determine the displacement resulting from an applied thrust. The LVDT sensor uses an analog interface, whereas the laser sensor uses a digital interface to communicate the displacement readings to the data acquisition equipment. The data collected by both sensors show good agreement for static mass calibrations and validation with a cold gas thruster. However, the data obtained using the LVDT deviate significantly from that of the laser sensor when operating two varieties of plasma thrusters: a radio frequency (RF) driven plasma thruster, and a DC powered plasma thruster. Results establish that even with appropriate shielding and signal filtering the LVDT sensor is subject to plasma noise and radio frequency interactions which result in anomalous thrust readings. Experimental data show that the thrust determined using the LVDT system in a direct current plasma environment and a RF discharge is approximately a factor of three higher than the thrust values obtained using a laser sensor system for the operating conditions investigated. These findings are of significance to the electric propulsion community as LVDT sensors are often utilized in thrust measurement systems and accurate thrust measurement and the reproducibility of thrust data is key to analyzing thruster performance. Methods are proposed to evaluate system susceptibility to plasma noise and an effective filtering scheme presented for DC discharges.

  12. Measuring ionospheric electron density using the plasma frequency probe

    SciTech Connect

    Jensen, M.D.; Baker, K.D. )

    1992-02-01

    During the past decade, the plasma frequency probe (PFP) has evolved into an accurate, proven method of measuring electron density in the ionosphere above about 90 km. The instrument uses an electrically short antenna mounted on a sounding rocket that is immersed in the plasma and notes the frequency where the antenna impedance is large and nonreactive. This frequency is closely related to the plasma frequency, which is a direct function of free electron concentration. The probe uses phase-locked loop technology to follow a changing electron density. Several sections of the plasma frequency probe circuitry are unique, especially the voltage-controlled oscillator that uses both an electronically tuned capacitor and inductor to give the wide tuning range needed for electron density measurements. The results from two recent sounding rocket flights (Thunderstorm II and CRIT II) under vastly different plasma conditions demonstrate the capabilities of the PFP and show the importance of in situ electron density measurements of understanding plasma processes. 9 refs.

  13. 10 CFR 455.110 - Grant application submittals for technical assistance and energy conservation measures.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Grant application submittals for technical assistance and... Grant application submittals for technical assistance and energy conservation measures. (a) Each... coordinating agencies for financial assistance for technical assistance programs shall include the...

  14. Graphene matrix for signal enhancement in ambient plasma assisted laser desorption ionization mass spectrometry.

    PubMed

    Chang, Cuilan; Li, Xianjiang; Bai, Yu; Xu, Gege; Feng, Baosheng; Liao, Yiping; Liu, Huwei

    2013-09-30

    In this work, the signal intensity of ambient plasma assisted laser desorption ionization mass spectrometry (PALDI-MS) was significantly increased with graphene as matrix. The graphene functions as a substrate to trap analytes, absorb energy from the visible laser irradiation and transfer energy to the analytes to facilitate the laser desorption process. The desorbed analytes are further ionized by helium plasma and analyzed by MS. Compared with a traditional organic matrix, α-cyano-4-hydroxycinnamic acid (CHCA), graphene exhibited much higher desorption efficiency for most of the compounds benefitting from the strong optical absorption at 532nm. The performance has been confirmed by the facile analysis of more than forty compounds with various structures. Additionally, this method was successfully applied to distinguish three kinds of Chinese tea leaves by detecting the endogenous caffeine and theanine, which proved the utility, facility and convenience of this method for rapid screening of main components in real samples.

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

    DOEpatents

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

    2010-11-02

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

  16. Formation and role of cool flames in plasma-assisted premixed combustion

    NASA Astrophysics Data System (ADS)

    Kim, W.; Mungal, M. G.; Cappelli, M. A.

    2008-02-01

    The structure of a plasma-assisted laminar premixed flame is studied numerically. The initial radical yield generated by a nonequilibrium discharge serves as the boundary condition for a one-dimensional flame code predicting the formation of a cool flame which pilots the premixed methane/air combustion. The ignition of the surrounding unactivated methane-air mixture by this cool flame is modeled as an opposed diffusion flame. Our findings indicate that the nonequilibrium discharge is an in situ reformer of the fuel for the production of the cool flame, producing primarily H2 and CO, thus, facilitating the burning of the lean methane-air mixture.

  17. Large-Area, Plasma-Assisted, Halogen-Based Diamond Deposition

    DTIC Science & Technology

    1992-03-04

    DTIC AD-A247 423 TIC RESEARCH TRIANGLE INSTITUTE RTI/5123/91-92 Quarterly March 1992 LARGE-AREA, PLASMA-ASSISTED, HALOGEN-BASED DIAMOND DEPOSITION...Quarterly Report - First and Second Quarters R.A. Rudder R.J. Markunas M.J. Mantini G.C. Hudson Office of Naval Research Program No. N00014-91-C-0177...fir , : u ____ 92-06469 POST OFFICE BOX 12194 RESEARCH TRIANGLE PARK NORTH CAROLINA 27709 2194 REPORT DOCUMENT PAGE Form Approved )OMB No 0704

  18. Growth mechanism of carbon nanotubes grown by microwave plasma-assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Muneyoshi, T.; Okai, M.; Yaguchi, T.; Sasaki, S.

    2001-10-01

    To investigate the most suitable deposition conditions and growth mechanism, we grew carbon nanotubes (CNTs) by microwave plasma-assisted chemical vapor deposition under various conditions. The experimental parameters we varied were (a) the mixture ratio of methane in hydrogen, (b) the total gas pressure, and (c) the bias electric current. We found that the bias electric current was the most influential parameter in determining the shape of CNTs. We believe that the growth process of CNTs can be explained by using the solid solubility curves of metal-carbon phase diagrams. Selective growth and low-temperature growth of CNTs can also be understood from these phase diagrams.

  19. Plasma assisted spectroscopic monitoring of alkali metals in pressurised combustion and gasification

    SciTech Connect

    Haeyrinen, V.T.; Hernberg, R.G.

    1995-07-01

    The paper describes an instrument for on-line concentration measurement of vaporised alkali compounds in pressurised industrial combustion and gasification processes. The measurement is based on Plasma Excited Alkali Resonance Line Spectroscopy (PEARLS) at the elevated pressure (1-3 MPa) of the process. Results are presented from laboratory calibration measurements and test measurements of sodium and potassium vapours resulting from the combustion of coal powder in a pressurised entrained flow reactor.

  20. Oxygen plasma power dependence on ZnO grown on porous silicon substrates by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Nam, Giwoong; Kim, Min Su; Kim, Do Yeob; Yim, Kwang Gug; Kim, Soaram; Kim, Sung-O.; Lee, Dong-Yul; Leem, Jae-Young

    2012-10-15

    ZnO thin films were deposited on porous silicon by plasma-assisted molecular beam epitaxy using different radio frequency power settings. Optical emission spectrometry was applied to study the characteristics of the oxygen plasma, and the effects of the radio frequency power on the properties of the ZnO thin films were evaluated by X-ray diffraction, scanning electron microscopy, and photoluminescence. The grain sizes for radio frequency powers of 100, 200, and 300 W were 46, 48, and 62 nm, respectively. In addition, the photoluminescence intensities of the ultraviolet and the visible range increased at 300 W, because the density of the atomic oxygen transitions increased. The quality of the ZnO thin films was enhanced, but the deep-level emission peaks increased with increasing radio frequency power. The structural and optical properties of the ZnO thin films were improved at the radio frequency power of 300 W. Moreover, the optical properties of the ZnO thin films were improved with porous silicon, instead of Si.

  1. Laser diagnostics and modeling of plasma assisted CVD. Final technical report

    SciTech Connect

    1996-02-01

    Plasma assisted chemical vapor deposition (PACVD) represents a novel approach for utilizing the nonequilibrium effects of reactive plasmas for depositing a wide range of protective hardface coatings that have both wear and erosion application. The nonequilibrium plasma is the heart of this complex system and has the function of generating the reactive molecular fragments (radicals) and atomic species at concentration levels unattainable by other competing processes. It is now widely accepted that such advanced protective hardface coatings materials will play a vital role in the energy technologies of the coming decades, with major applications in diverse areas ranging from aerospace and commercial propulsion systems (jet engines) to automotive components and internal combustion engines, (ceramic heat engines), cutting and machining tools, electronic packaging, thermal management, and possibly room-temperature superconductors. Wear and associated erosion aspects are responsible for an enormous expenditure of energy and fiscal resources in almost all DOE applications. Many of the results from this investigation arc also applicable to other materials processing reactors such as electron beam, PVD, CVD, laser ablation, microwave, high energy cathodic arc, thermal plasma (rf or dc) and combustion spray. These also include the various hybrid systems such as the rf/dc arc as used in Japan for diamond deposition and e-beam PVD deposition of advanced titanium alloy coatings as used at the Paton Institute in Kiev, Ukraine.

  2. Tailoring carbon nanotips in the plasma-assisted chemical vapor deposition: Effect of the process parameters

    SciTech Connect

    Wang, B. B.; Ostrikov, K.

    2009-04-15

    Carbon nanotips have been synthesized from a thin carbon film deposited on silicon by bias-enhanced hot filament chemical vapor deposition under different process parameters. The results of scanning electron microscopy indicate that high-quality carbon nanotips can only be obtained under conditions when the ion flux is effectively drawn from the plasma sustained in a CH{sub 4}+NH{sub 3}+H{sub 2} gas mixture. It is shown that the morphology of the carbon nanotips can be controlled by varying the process parameters such as the applied bias, gas pressure, and the NH{sub 3}/H{sub 2} mass flow ratios. The nanotip formation process is examined through a model that accounts for surface diffusion, in addition to sputtering and deposition processes included in the existing models. This model makes it possible to explain the major difference in the morphologies of the carbon nanotips formed without and with the aid of the plasma as well as to interpret the changes of their aspect ratio caused by the variation in the ion/gas fluxes. Viable ways to optimize the plasma-based process parameters to synthesize high-quality carbon nanotips are suggested. The results are relevant to the development of advanced plasma-/ion-assisted methods of nanoscale synthesis and processing.

  3. Numerical study of nonequilibrium plasma assisted detonation initiation in detonation tube

    NASA Astrophysics Data System (ADS)

    Zhou, Siyin; Wang, Fang; Che, Xueke; Nie, Wansheng

    2016-12-01

    Nonequilibrium plasma has shown great merits in ignition and combustion nowadays, which should be especially useful for hypersonic propulsion. A coaxial electrodes configuration was established to investigate the effect of alternating current (AC) dielectric barrier discharge nonequilibrium plasma on the detonation initiation process in a hydrogen-oxygen mixture. A discharge simulation-combustion simulation loosely coupled method was used to simulate plasma assisted detonation initiation. First, the dielectric barrier discharge in the hydrogen-oxygen mixture driven by an AC voltage was simulated, which takes 17 kinds of particles (including positively charged particles, negatively charged particles, and neutral particles) and 47 reactions into account. The temporal and spatial characteristics of the discharge products were obtained. Then, the discharge products were incorporated into the combustion model of a detonation combustor as the initial conditions for the later detonation initiation simulation. Results showed that the number density distributions of plasma species are different in space and time, and develop highly nonuniformly from high voltage electrode to grounded electrode at certain times. All the active species reach their highest concentration at approximately 0.6T (T denotes a discharge cycle). Compared with the no plasma case, the differences of flowfield shape mainly appear in the early stage of the deflagration to detonation transition process. None of the sub-processes (including the very slow combustion, deflagration, over-driven detonation, detonation decay, and propagation of a self-sustained stable detonation wave) have been removed by the plasma. After the formation of a C-J detonation wave, the whole flowfield remains unchanged. With the help of plasma, the deflagration to detonation transition (DDT) time and distance are reduced by about 11.6% and 12.9%, respectively, which should be attributed to the active particles effect of

  4. Electrical Conductivity Measurement of Nonideal Carbon Plasma

    DTIC Science & Technology

    2008-08-01

    conductivity as a function of density and temperature. The pressure and temperature were determined with the aid of SESAME -tabulated equation of state ( EOS ...samples in which the SESAME EOS database was a necessary part of the analysis. Using the present technique, we do not require the use of a tabulated...obtain an estimate of temperature, we can refer our data to the EOS for carbon-a7830 in the SESAME database. We have inserted our measurements for

  5. Antenna impedance measurements in a magnetized plasma. I. Spherical antenna

    SciTech Connect

    Blackwell, David D.; Walker, David N.; Messer, Sarah J.; Amatucci, William E.

    2007-09-15

    The input impedance of a metal sphere immersed in a magnetized plasma is measured with a network analyzer at frequencies up to 1 GHz. The experiments were done in the Space Physics Simulation Chamber at the Naval Research Laboratory. The hot-filament argon plasma was varied between weakly ({omega}{sub ce}<{omega}{sub pe}) and strongly ({omega}{sub ce}>{omega}{sub pe}) magnetized plasma with electron densities in the range 10{sup 7}-10{sup 10} cm{sup -3}. It is observed that the lower-frequency resonance of the impedance characteristic previously associated with series sheath resonance {omega}{sub sh} in the unmagnetized plasma occurs at a hybrid sheath frequency of {omega}{sub r}{sup 2}={omega}{sub sh}{sup 2}+{kappa}{omega}{sub ce}{sup 2}, where {kappa} is a constant 0.5<{kappa}<1. As seen in previous experiments, the higher frequency resonance associated with the electron plasma frequency {omega}{sub pe} in the unmagnetized plasma is relocated to the upper hybrid frequency {omega}{sub uh}{sup 2}={omega}{sub pe}{sup 2}+{omega}{sub ce}{sup 2}. As with the unmagnetized plasma, the maximum power deposition occurs at the lower frequency resonance {omega}{sub r}.

  6. Operational Characteristics and Plasma Measurements in a Low-Energy FARAD Thruster

    NASA Technical Reports Server (NTRS)

    Polzin, K. A.; Best, S.; Rose, M. F.; Miller, R.; Owens, T.

    2008-01-01

    Pulsed inductive plasma accelerators are spacecraft propulsion devices in which energy is stored in a capacitor and then discharged through an inductive coil. The device is electrodeless, inducing a plasma current sheet in propellant located near the face of the coil. The propellant is accelerated and expelled at a high exhaust velocity (order of 10 km/s) through the interaction of the plasma current with an induced magnetic field. The Faraday Accelerator with RF-Assisted Discharge (FARAD) thruster is a type of pulsed inductive plasma accelerator in which the plasma is preionized by a mechanism separate from that used to form the current sheet and accelerate the gas. Employing a separate preionization mechanism in this manner allows for the formation of an inductive current sheet at much lower discharge energies and voltages than those found in previous pulsed inductive accelerators like the Pulsed Inductive Thruster (PIT). In this paper, we present measurements aimed at quantifying the thruster's overall operational characteristics and providing additional insight into the nature of operation. Measurements of the terminal current and voltage characteristics during the pulse help quantify the output of the pulsed power train driving the acceleration coil. A fast ionization gauge is used to measure the evolution of the neutral gas distribution in the accelerator prior to a pulse. The preionization process is diagnosed by monitoring light emission from the gas using a photodiode, and a time-resolved global view of the evolving, accelerating current sheet is obtained using a fast-framing camera. Local plasma and field measurements are obtained using an array of intrusive probes. The local induced magnetic field and azimuthal current density are measured using B-dot probes and mini-Rogowski coils, respectively. Direct probing of the number density and electron temperature is performed using a triple probe.

  7. Aerosol and Plasma Measurements in Noctilucent Clouds

    NASA Technical Reports Server (NTRS)

    Robertson, Scott

    2000-01-01

    The purpose of this project was to develop rocket-borne probes to detect charged aerosol layers in the mesosphere. These include sporadic E layers, which have their origin in meteoric dust, and noctilucent clouds, which form in the arctic summer and are composed of ice crystals. The probe being developed consists of a charge collecting patch connected to a sensitive electrometer which measures the charge deposited on the patch by impacting aerosols. The ambient electrons and light ions in the mesosphere are prevented from being collected by a magnetic field. The magnetic force causes these lighter particles to turn so that they miss the collecting patch.

  8. Tuning the Electrical Properties of Graphene via Nitrogen Plasma-Assisted Chemical Modification.

    PubMed

    Jung, Min Wook; Song, Wooseok; Jung, Dae Sung; Lee, Sun Sook; Park, Chong-Yun; An, Ki-Seok

    2016-03-01

    The control in electrical properties of graphene is essentially required in order to realize graphenebased nanoelectronics. In this study, N-doped graphene was successfully obtained via nitrogen plasma treatment. Graphene was synthesized on copper foil using thermal chemical vapor deposition. After N2 plasma treatment, the G-band of the graphene was blueshifted and the intensity ratio of 2D- to G-bands decreased with increasing the plasma power. Pyrrolic-N bonding configuration induced by N2 plasma treatment was studied by X-ray photoelectron spectroscopy. Remarkably, electrical characterization including Hall measurement and I-V characteristics of the N-doped graphene exhibit semiconducting behavior as well as the n-type doping effect.

  9. Simultaneous Multi-angle Measurements of Plasma Turbulence at HAARP

    NASA Astrophysics Data System (ADS)

    Watanabe, Naomi; Golkowski, Mark; Sheerin, James; University of Colorado Denver Team

    2013-10-01

    We report the results from a recent series of experiments employing the HAARP HF transmitter to generate and study strong Langmuir turbulence (SLT) in the interaction region of overdense ionospheric plasma. Diagnostics included the Modular UHF Ionospheric Radar (MUIR) located at HAARP, the Super DARN-Kodiak HF radar, and HF receivers to record stimulated electromagnetic emissions (SEE). Short pulse, low duty cycle experiments demonstrate control and suppression of artificial field-aligned irregularities (AFAI). This allows the isolation of ponderomotive plasma turbulence effects. For the first time, plasma line spectra measured simultaneously in different spots of the interaction region displayed marked but contemporaneous differences dependent on the aspect angle of the HF pump beam and the pointing angle of the MUIR diagnostic radar. Outshifted Plasma Line (OPL) spectra, rarely observed in past experiments, occurred with sufficient regularity for experimentation. Experimental results are compared to previous high latitude experiments and predictions from recent modeling efforts.

  10. Simultaneous Multi-angle Measurements of Plasma Turbulence at HAARP

    NASA Astrophysics Data System (ADS)

    Watanabe, Naomi

    We report the results from a recent series of experiments employing the HAARP HF transmitter to generate and study strong Langmuir turbulence (SLT) in the interaction region of overdense ionospheric plasma. Diagnostics included the Modular UHF Ionospheric Radar (MUIR) sited at HAARP, the Super DARN-Kodiak HF radar, and HF receivers to record stimulated electromagnetic emissions (SEE). Short pulse, low duty cycle experiments demonstrate control and suppression of artificial field-aligned irregularities (AFAI). This allows the isolation of ponderomotive plasma turbulence effects. For the first time, plasma line spectra measured simultaneously in different spots of the interaction region displayed marked but contemporaneous differences dependent on the aspect angle of the HF pump beam and the pointing angle of the MUIR diagnostic radar. Outshifted Plasma Line spectra, rarely observed in past experiments, occurred with sufficient regularity for experimentation. Experimental results are compared to previous high latitude experiments and predictions from recent modeling efforts.

  11. OPACITY MEASUREMENT AND THEORETICAL INVESTIGATION OF HOT SILICON PLASMA

    SciTech Connect

    Xiong, Gang; Yang, Jiamin; Zhang, Jiyan; Hu, Zhimin; Zhao, Yang; Qing, Bo; Yang, Guohong; Wei, Minxi; Yi, Rongqing; Song, Tianming; Li, Hang; Yuan, Zheng; Lv, Min; Meng, Xujun; Xu, Yan; Wu, Zeqing; Yan, Jun E-mail: zhimin.hu@yahoo.com

    2016-01-01

    We report on opacity measurements of a silicon (Si) plasma at a temperature of (72 ± 5) eV and a density of (6.0 ± 1.2) mg cm{sup −3} in the photon energy range of 1790–1880 eV. A 23 μg cm{sup −2} Si foil tamped by 50 μg cm{sup −2} CH layers on each side was heated to a hot-dense plasma state by X-ray radiation emitted from a D-shaped gold cavity that was irradiated by intense lasers. Absorption lines of 1s − 2p transitions of Si xiii to Si ix ions have been measured using point-projection spectroscopy. The transmission spectrum of the silicon plasma was determined by comparing the light passing through the plasma to the light from the same shot passing by the plasma. The density of the Si plasma was determined experimentally by side-on radiography and the temperature was estimated from the radiation flux data. Radiative hydrodynamic simulations were performed to obtain the temporal evolutions of the density and temperature of the Si plasma. The experimentally obtained transmission spectra of the Si sample plasma have been reproduced using a detailed term account model with the local thermodynamic equilibrium approximation. The energy levels, oscillator strengths and photoionization cross-sections used in the calculation were generated by the flexible atomic code. The experimental transmission spectrum was compared with the theoretical calculation and good agreement was found. The present experimental spectrum and theoretical calculation were also compared with the new opacities available in the Los Alamos OPLIB database.

  12. Opacity Measurement and Theoretical Investigation of Hot Silicon Plasma

    NASA Astrophysics Data System (ADS)

    Xiong, Gang; Yang, Jiamin; Zhang, Jiyan; Hu, Zhimin; Zhao, Yang; Qing, Bo; Yang, Guohong; Wei, Minxi; Yi, Rongqing; Song, Tianming; Li, Hang; Yuan, Zheng; Lv, Min; Meng, Xujun; Xu, Yan; Wu, Zeqing; Yan, Jun

    2016-01-01

    We report on opacity measurements of a silicon (Si) plasma at a temperature of (72 ± 5) eV and a density of (6.0 ± 1.2) mg cm-3 in the photon energy range of 1790-1880 eV. A 23 μg cm-2 Si foil tamped by 50 μg cm-2 CH layers on each side was heated to a hot-dense plasma state by X-ray radiation emitted from a D-shaped gold cavity that was irradiated by intense lasers. Absorption lines of 1s - 2p transitions of Si xiii to Si ix ions have been measured using point-projection spectroscopy. The transmission spectrum of the silicon plasma was determined by comparing the light passing through the plasma to the light from the same shot passing by the plasma. The density of the Si plasma was determined experimentally by side-on radiography and the temperature was estimated from the radiation flux data. Radiative hydrodynamic simulations were performed to obtain the temporal evolutions of the density and temperature of the Si plasma. The experimentally obtained transmission spectra of the Si sample plasma have been reproduced using a detailed term account model with the local thermodynamic equilibrium approximation. The energy levels, oscillator strengths and photoionization cross-sections used in the calculation were generated by the flexible atomic code. The experimental transmission spectrum was compared with the theoretical calculation and good agreement was found. The present experimental spectrum and theoretical calculation were also compared with the new opacities available in the Los Alamos OPLIB database.

  13. Solar oscillation time delay measurement assisted celestial navigation method

    NASA Astrophysics Data System (ADS)

    Ning, Xiaolin; Gui, Mingzhen; Zhang, Jie; Fang, Jiancheng; Liu, Gang

    2017-05-01

    Solar oscillation, which causes the sunlight intensity and spectrum frequency change, has been studied in great detail, both observationally and theoretically. In this paper, owing to the existence of solar oscillation, the time delay between the sunlight coming from the Sun directly and the sunlight reflected by the other celestial body such as the satellite of planet or asteroid can be obtained with two optical power meters. Because the solar oscillation time delay is determined by the relative positions of the spacecraft, reflective celestial body and the Sun, it can be adopted as the navigation measurement to estimate the spacecraft's position. The navigation accuracy of single solar oscillation time delay navigation system depends on the time delay measurement accuracy, and is influenced by the distance between spacecraft and reflective celestial body. In this paper, we combine it with the star angle measurement and propose a solar oscillation time delay measurement assisted celestial navigation method for deep space exploration. Since the measurement model of time delay is an implicit function, the Implicit Unscented Kalman Filter (IUKF) is applied. Simulations demonstrate the effectiveness and superiority of this method.

  14. Measurement of the edge plasma rotation on J-TEXT tokamak

    SciTech Connect

    Cheng, Z. F.; Luo, J.; Wang, Z. J.; Zhang, Z. P.; Zhang, X. L.; Hou, S. Y.; Cheng, C.; Zhuang, G.

    2013-07-15

    A multi-channel high resolution spectrometer was developed for the measurement of the edge plasma rotation on J-TEXT tokamak. With the design of two opposite viewing directions, the poloidal and toroidal rotations can be measured simultaneously, and velocity accuracy is up to 1 km/s. The photon flux was enhanced by utilizing combined optical fiber. With this design, the time resolution reaches 3 ms. An assistant software “Spectra Assist” was developed for implementing the spectrometer control and data analysis automatically. A multi-channel monochromatic analyzer is designed to get the location of chosen ions simultaneously through the inversion analysis. Some preliminary experimental results about influence of plasma density, different magnetohydrodynamics behaviors, and applying of biased electrode are presented.

  15. Measurement of dielectric-film thickness at low density plasma

    NASA Astrophysics Data System (ADS)

    Jeon, Sang-Bum; Kim, Dong-Hwan; Kim, Jin-Yong; Paek, Se-Yeol; Chung, Chin-Wook

    2016-09-01

    The measurement system of dielectric-film thickness was improved to measure thin-film at low density plasma. There are three improvements than previous method, which is electrical measurement of dielectric-film thickness using R-C sheath model. First, the frequency of input voltage was decreased to reduce the ratio of the dielectric-film impedance to sheath impedance. Second, three different frequencies were used to overcome the inaccuracy of measured phase; only amplitudes of measured current were used to obtain a film thickness. Third, the notch filter was used for sensing current instead of the resistor to improve the signal to noise ratio. Using this method, dielectric-film thickness was well measured at low density plasma (thickness: 300, sheath impedance: 100 200 k Ω) .

  16. Measurements of uranium mass confined in high density plasmas

    NASA Technical Reports Server (NTRS)

    Stoeffler, R. C.

    1976-01-01

    An X-ray absorption method for measuring the amount of uranium confined in high density, rf-heated uranium plasmas is described. A comparison of measured absorption of 8 keV X-rays with absorption calculated using Beer Law indicated that the method could be used to measure uranium densities from 3 times 10 to the 16th power atoms/cu cm to 5 times 10 to the 18th power atoms/cu cm. Tests were conducted to measure the density of uranium in an rf-heated argon plasma with UF6 infection and with the power to maintain the discharge supplied by a 1.2 MW rf induction heater facility. The uranium density was measured as the flow rate through the test chamber was varied. A maximum uranium density of 3.85 times 10 to the 17th power atoms/cu cm was measured.

  17. Measurements of uranium mass confined in high density plasmas

    NASA Technical Reports Server (NTRS)

    Stoeffler, R. C.

    1976-01-01

    An X-ray absorption method for measuring the amount of uranium confined in high density, rf-heated uranium plasmas is described. A comparison of measured absorption of 8 keV X-rays with absorption calculated using Beer Law indicated that the method could be used to measure uranium densities from 3 times 10 to the 16th power atoms/cu cm to 5 times 10 to the 18th power atoms/cu cm. Tests were conducted to measure the density of uranium in an rf-heated argon plasma with UF6 infection and with the power to maintain the discharge supplied by a 1.2 MW rf induction heater facility. The uranium density was measured as the flow rate through the test chamber was varied. A maximum uranium density of 3.85 times 10 to the 17th power atoms/cu cm was measured.

  18. Picosecond time-resolved measurements of dense plasma line shifts

    DOE PAGES

    Stillman, C. R.; Nilson, P. M.; Ivancic, S. T.; ...

    2017-06-13

    Picosecond time-resolved x-ray spectroscopy is used to measure the spectral line shift of the 1s2p–1s2 transition in He-like Al ions as a function of the instantaneous plasma conditions. The plasma temperature and density are inferred from the Al Heα complex using a nonlocal-thermodynamic-equilibrium atomic physics model. The experimental spectra show a linearly increasing red shift for electron densities of 1 to 5 × 1023 cm–3. Furthermore, the measured line shifts are broadly consistent with a generalized analytic line-shift model based on calculations of a self-consistent field ion sphere model.

  19. Measurement of pulse pressure in plasma by crusher gauge

    SciTech Connect

    Kalachnikov, E.V.; Rogovtsev, P.N.

    1988-06-01

    Results are presented of pressure measurements in the plasma of a stabilized pinched discharge with axial blow through of the current channel by plasma using static and dynamic methods for crusher gauge calibration. Accuracies for maximum pressure measurements for both calibration methods are evaluated. The dynamic properties of the crusher gauge are taken into account experimentally in studying pulse forces and pressures in the 1-100 MPa range for times of 10/sup /minus/5/ to 10/sup /minus/3/ seconds. A piezoelectric method and device for dynamic calibration of the pressure gauges is described.

  20. Picosecond time-resolved measurements of dense plasma line shifts

    NASA Astrophysics Data System (ADS)

    Stillman, C. R.; Nilson, P. M.; Ivancic, S. T.; Golovkin, I. E.; Mileham, C.; Begishev, I. A.; Froula, D. H.

    2017-06-01

    Picosecond time-resolved x-ray spectroscopy is used to measure the spectral line shift of the 1 s 2 p -1 s2 transition in He-like Al ions as a function of the instantaneous plasma conditions. The plasma temperature and density are inferred from the Al H eα complex using a nonlocal-thermodynamic-equilibrium atomic physics model. The experimental spectra show a linearly increasing redshift for electron densities of 1 -5 ×1023c m-3 . The measured line shifts are broadly consistent with a generalized analytic line-shift model based on calculations of a self-consistent field ion-sphere model.

  1. Uncertainty propagation in modeling of plasma-assisted hydrogen production from biogas

    NASA Astrophysics Data System (ADS)

    Zaherisarabi, Shadi; Venkattraman, Ayyaswamy

    2016-10-01

    With the growing concern of global warming and the resulting emphasis on decreasing greenhouse gas emissions, there is an ever-increasing need to utilize energy-production strategies that can decrease the burning of fossil fuels. In this context, hydrogen remains an attractive clean-energy fuel that can be oxidized to produce water as a by-product. In spite of being an abundant species, hydrogen is seldom found in a form that is directly usable for energy-production. While steam reforming of methane is one popular technique for hydrogen production, plasma-assisted conversion of biogas (carbon dioxide + methane) to hydrogen is an attractive alternative. Apart from producing hydrogen, the other advantage of using biogas as raw material is the fact that two potent greenhouse gases are consumed. In this regard, modeling is an important tool to understand and optimize plasma-assisted conversion of biogas. The primary goal of this work is to perform a comprehensive statistical study that quantifies the influence of uncertain rate constants thereby determining the key reaction pathways. A 0-D chemical kinetics solver in the OpenFOAM suite is used to perform a series of simulations to propagate the uncertainty in rate constants and the resulting mean and standard deviation of outcomes.

  2. Single-crystal N-polar GaN p-n diodes by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Cho, YongJin; Hu, Zongyang; Nomoto, Kazuki; Xing, Huili Grace; Jena, Debdeep

    2017-06-01

    N-polar GaN p-n diodes are realized on single-crystal N-polar GaN bulk wafers by plasma-assisted molecular beam epitaxy growth. The current-voltage characteristics show high-quality rectification and electroluminescence characteristics with a high on currents ˜10 kA/cm2, low off currents <10-5 A/cm2, on/off current ratio of >109, and interband photon emission. The measured electroluminescence spectrum is dominated by a strong near-band edge emission, while deep level luminescence is greatly suppressed. A very low dislocation density leads to a high reverse breakdown electric field of ˜2.2 MV/cm without fields plates—the highest reported for N-polar epitaxial structures. The low leakage current N-polar diodes open up several potential applications in polarization-engineered photonic and electronic devices.

  3. Growth, Structural, and Electrical Characterizations of N-Polar InAlN by Plasma-Assisted Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Dasgupta, Sansaptak; Nidhi; Choi, Soojeong; Wu, Feng; Speck, James S.; Mishra, Umesh K.

    2011-04-01

    N-polar InxAl1-xN (0.02 < x < 0.65) films were grown and characterized by plasma-assisted molecular beam epitaxy (PAMBE). Indium incorporation in the films was characterized both as a function of the impinging In and Al flux and the growth temperature. In incorporation in the film was found to decrease with increasing growth temperature (Tgr) for Tgr > 560 °C. A smooth surface morphology was obtained for In0.18Al0.82N lattice-matched to GaN. Subsequently, N-polar In0.18Al0.82N was used as a charge-inducing barrier in a N-polar GaN HEMT structure and electrical characterizations including current-voltage (I-V) measurements were performed.

  4. Growth and Characterization of N-Polar GaN Films on Si(111) by Plasma Assisted Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Dasgupta, Sansaptak; Nidhi; Wu, Feng; Speck, James S.; Mishra, Umesh K.

    2012-11-01

    Smooth N-polar GaN films were epitaxially grown by plasma assisted molecular beam epitaxy (PAMBE) on on-axis p-Si(111). The structural quality of the as-grown GaN films was further improved by insertion of AlGaN/GaN superlattice structures, resulting in reduced threading dislocation density and also efficient stress management in the GaN film to mitigate crack formation. The structural quality of these films was comparable to N-polar GaN grown on C-SiC by MBE. Convergent beam electron diffraction (CBED) imaging and KOH etch studies were performed to confirm the N-polarity of the sample. Room temperature photoluminescence measurements revealed strong GaN band-edge emission.

  5. Ge doping of β-Ga2O3 films grown by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Ahmadi, Elaheh; Koksaldi, Onur S.; Kaun, Stephen W.; Oshima, Yuichi; Short, Dane B.; Mishra, Umesh K.; Speck, James S.

    2017-04-01

    The Ge doping of β-Ga2O3(010) films was investigated using plasma-assisted molecular beam epitaxy as the growth method. The dependences of the amount of Ge incorporated on the substrate temperature, Ge-cell temperature, and growth regime were studied by secondary ion mass spectrometry. The electron concentration and mobility were investigated using Van der Pauw Hall patterns. Hall measurement confirmed that Ge acts as an n-dopant in β-Ga2O3(010) films. These results were compared with similar films doped by Sn. The Hall data showed an improved electron mobility for the same electron concentration when Ge is used instead of Sn as the dopant.

  6. VO2 Thermochromic Films on Quartz Glass Substrate Grown by RF-Plasma-Assisted Oxide Molecular Beam Epitaxy

    PubMed Central

    Zhang, Dong; Sun, Hong-Jun; Wang, Min-Huan; Miao, Li-Hua; Liu, Hong-Zhu; Zhang, Yu-Zhi; Bian, Ji-Ming

    2017-01-01

    Vanadium dioxide (VO2) thermochromic thin films with various thicknesses were grown on quartz glass substrates by radio frequency (RF)-plasma assisted oxide molecular beam epitaxy (O-MBE). The crystal structure, morphology and chemical stoichiometry were investigated systemically by X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses. An excellent reversible metal-to-insulator transition (MIT) characteristics accompanied by an abrupt change in both electrical resistivity and optical infrared (IR) transmittance was observed from the optimized sample. Remarkably, the transition temperature (TMIT) deduced from the resistivity-temperature curve was reasonably consistent with that obtained from the temperature-dependent IR transmittance. Based on Raman measurement and XPS analyses, the observations were interpreted in terms of residual stresses and chemical stoichiometry. This achievement will be of great benefit for practical application of VO2-based smart windows. PMID:28772673

  7. VO₂ Thermochromic Films on Quartz Glass Substrate Grown by RF-Plasma-Assisted Oxide Molecular Beam Epitaxy.

    PubMed

    Zhang, Dong; Sun, Hong-Jun; Wang, Min-Huan; Miao, Li-Hua; Liu, Hong-Zhu; Zhang, Yu-Zhi; Bian, Ji-Ming

    2017-03-19

    Vanadium dioxide (VO₂) thermochromic thin films with various thicknesses were grown on quartz glass substrates by radio frequency (RF)-plasma assisted oxide molecular beam epitaxy (O-MBE). The crystal structure, morphology and chemical stoichiometry were investigated systemically by X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses. An excellent reversible metal-to-insulator transition (MIT) characteristics accompanied by an abrupt change in both electrical resistivity and optical infrared (IR) transmittance was observed from the optimized sample. Remarkably, the transition temperature (TMIT) deduced from the resistivity-temperature curve was reasonably consistent with that obtained from the temperature-dependent IR transmittance. Based on Raman measurement and XPS analyses, the observations were interpreted in terms of residual stresses and chemical stoichiometry. This achievement will be of great benefit for practical application of VO₂-based smart windows.

  8. Polarity control and transport properties of Mg-doped (0001) InN by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Choi, Soojeong; Wu Feng; Bierwagen, Oliver; Speck, James S.

    2013-05-15

    The authors report on the plasma-assisted molecular beam epitaxy growth and carrier transport of Mg-doped In-face (0001) InN. The 1.2 {mu}m thick InN films were grown on GaN:Fe templates under metal rich conditions with Mg concentration from 1 Multiplication-Sign 10{sup 17}/cm{sup 3} to 3 Multiplication-Sign 10{sup 20}/cm{sup 3}. A morphological transition, associated with the formation of V-shape polarity inversion domains, was observed at Mg concentration over 7 Multiplication-Sign 10{sup 19}/cm{sup 3} by atomic force microscopy and transmission electron microscopy. Seebeck measurements indicated p-type conductivity for Mg-concentrations from 9 Multiplication-Sign 10{sup 17}/cm{sup 3} to 7 Multiplication-Sign 10{sup 19}/cm{sup 3}, i.e., as it exceeded the compensating (unintentional) donor concentration.

  9. The determination of trace element concentrations in fly ash samples using ultrasound-assisted digestion followed with inductively coupled plasma optical emission spectrometry.

    PubMed

    Ilander, Aki; Väisänen, Ari

    2009-08-01

    A method of ultrasound-assisted digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) used for the determination of trace element (chromium, copper, lead, nickel, vanadium and zinc) concentrations in fly ash samples was developed. All the measurements were performed in robust plasma conditions. Ultrasound-assisted digestion procedures using digestion solutions of aqua regia and hydrofluoric acid (HF) resulted in recovery rates of over 80% for all the analyte elements. Ultrasound-assisted two-step digestion with digestion solutions of 6mL of HNO(3) (Step 1) and 3mL of HNO(3)+3mL of HF (Step 2) resulted in recovery rates of over 92% for all the analyte elements with one exception, chromium, which had a recovery of about 85%. The analysis of SRM 1633b showed that the two-step ultrasound-assisted digestion method developed resulted in chromium, copper, nickel and zinc concentrations higher than the microwave digestion method standardized by the United States Environmental Protection Agency (USEPA method 3052). This is the very first time when a digestion method using ultrasound resulted in higher efficiency than microwave (USEPA method 3052) for chromium and nickel in very hard to dissolve samples. The major advantages of the ultrasound-assisted digestion over microwave digestion is the high treatment rate (about 30 samples simultaneously with a sonication time of 18min) and the possibility to use new sample vessels without a significant increase in costs.

  10. Measurement of the plasma radial electric field by the motional Stark effect diagnostic on JET plasmas

    NASA Astrophysics Data System (ADS)

    Reyes Cortes, S.; Hawkes, N. C.; Lotte, P.; Fenzi, C.; Stratton, B. C.; Hobirk, J.; De Angelis, R.; Orsitto, F.; Varandas, C. A. F.

    2003-03-01

    The radial electric field gradient or the E×B flow shear has been pointed out as the underlying mechanism for turbulence suppression, responsible for an internal transport barrier formation in advanced tokamak scenarios. A comprehensive study on these subjects requires a direct measurement of the plasma radial electric field Er. The poloidal component of the magnetic field is assessed by the motional Stark effect (MSE) polarimeter, which is currently a standard diagnostic in fusion devices, allowing a local and nonperturbative measurement of the magnetic pitch angle. A precise measure to the state of polarization of the Stark components gives the information on the direction of the magnetic field. Due to the particular orientation of the Lorentz component, that is nearly perpendicular to Er, the MSE diagnostic is very sensitive to the plasma intrinsic radial electric field. This article describes a technique to measure Er involving the change of the polarization angle of the MSE emission, by using two beam injectors at different energies, firing sequentially. Experimental results for the low Er case, i.e., with very little plasma rotation, showing the ability of the MSE to perform this measurement, will be presented. This is the first time that evidence of a direct measurement of the plasma Er is reported from the Joint European Torus.

  11. Electrical Conductivity Measurements in Strongly Coupled Metal Plasmas

    NASA Astrophysics Data System (ADS)

    Desilva, Alan; Katsouros, Joseph

    1999-11-01

    We measure the electrical conductivity of strongly coupled plasmas of various metals, including aluminum, iron, copper, and tungsten, in the temperature range 6-30 kK, in a density range from about 1/2 solid density down to about 10-3 times solid density. These plasmas may have coupling parameters (ratio of mean interparticle Coulomb energy to mean kinetic energy) ranging from as high as 50 down to unity. Plasmas are created by rapid vaporization of metal wire in a water bath which act as a tamper. Streak photography serves to determine the growth of the plasma radius in time, allowing determination of mean density. Temperature is deduced from the measured energy input in conjunction with an equation of state from the LANL SESAME database [1], and a brightness temperature may be obtained from radiation measurements. The column resistance is determined from time-resolved voltage and current measurements. Results of conductivity measurements will be shown and compared with the predictions of conductivity theories. 1.SESAME: The Los Alamos National Laboratory Equation of State Database, Report LA-UR-92-3407, ed. S. P. Lyon and J. D. Johnson, Group T-1.

  12. Field-assisted paper spray mass spectrometry for therapeutic drug monitoring: 1.the case of imatinib in plasma.

    PubMed

    D'Aronco, Sara; Dall'Armi, Mattia; Crotti, Sara; Calandra, Eleonora; Traldi, Pietro; Di Marco, Valerio; Buonadonna, Angela; Corona, Giuseppe; Giodini, Luciana; Marangon, Elena; Posocco, Bianca; Toffoli, Giuseppe; Agostini, Marco

    2017-03-02

    The field-assisted paper spray (FAPS) - mass spectrometric method has been employed to quantify the imatinib (IMT) plasma levels in treated patients. The quantitative measurements have been performed on the collisionally generated fragment at m/z 394 of the protonated molecules of IMT and deuterated imatinib (d3 -IMT), used as internal standard. The FAPS-MS/MS method exhibits some limitations, due to the high number of operative parameters that need to be carefully controlled. For this aim paper supports of different geometry and different thickness and porosity were tested. To obtain a more focalised and intense electrical field a stainless steel needle was mounted axially and placed at 4 kV voltage. The variability observed in the measurements was ascribed either to the inter-individual variability (e.g. the concomitant presence of other compounds such as: proteins, lipids, drugs, and/or salts in the plasma of different patients) or to the uncontrollable variables in the instrumental set-up (e.g. sample deposition, changes in paper spray conditions). Furthermore, the manual sample deposition and solvent dripping strongly affects the measure reproducibility. Despite this, it is interesting to observe that, once applied in blind on 24 real plasma samples, FAPS-MS/MS led to results analogous to those obtained by the well consolidated LC-MS/MS, even if the mean %CV values of 20.4% and 2.6% were observed for the two methods, respectively. In conclusion, despite CV values are relatively high, it is worth noting that the FAPS-MS/MS method is much more straightforward, rapid and economical than the LC-MS/MS one, and it appears therefore very promising for applications where a high precision is not always a required task, as e.g. in some cases of therapeutic drug monitoring.

  13. Time-resolved aluminium laser-induced plasma temperature measurements

    NASA Astrophysics Data System (ADS)

    Surmick, D. M.; Parigger, C. G.

    2014-11-01

    We seek to characterize the temperature decay of laser-induced plasma near the surface of an aluminium target from laser-induced breakdown spectroscopy measurements of aluminium alloy sample. Laser-induced plasma are initiated by tightly focussing 1064 nm, nanosecond pulsed Nd:YAG laser radiation. Temperatures are inferred from aluminium monoxide spectra viewed at systematically varied time delays by comparing experimental spectra to theoretical calculations with a Nelder Mead algorithm. The temperatures are found to decay from 5173 ± 270 to 3862 ± 46 Kelvin from 10 to 100 μs time delays following optical breakdown. The temperature profile along the plasma height is also inferred from spatially resolved spectral measurements and the electron number density is inferred from Stark broadened Hβ spectra.

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

    SciTech Connect

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

    1980-01-01

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

  15. Laser system for measuring small changes in plasma tracer concentrations.

    PubMed

    Klaesner, J W; Pou, N A; Parker, R E; Galloway, R L; Roselli, R J

    1996-01-01

    The authors developed a laser-diode system that can be used for on-line optical concentration measurements in physiologic systems. Previous optical systems applied to whole blood have been hampered by artifacts introduced by red blood cells (RBCs). The system introduced here uses a commercially available filter cartridge to separate RBCs from plasma before plasma concentration measurements are made at a single wavelength. The filtering characteristics of the Cellco filter cartridge (#4007-10, German-town, MD) were adequate for use in the on-line measurement system. The response time of the filter cartridge was less than 40 seconds, and the sieving characteristics of the filter for macromolecules were excellent, with filtrate-to-plasma albumin ratios of 0.98 +/- 0.11 for studies in sheep and 0.94 +/- 0.15 for studies in dogs. The 635-nm laser diode system developed was shown to be more sensitive than the spectrophotometer used in previous studies (Klaesner et al., Annals of Biomedical Engineering, 1994; 22, 660-73). The new system was used to measure the product of filtration coefficient (Kfc) and reflection coefficient for albumin (delta f) in an isolated canine lung preparation. The delta fKfc values [mL/(cmH2O.min.100 g dry lung weight)] measured with the laser diode system (0.33 +/- 0.22) compared favorably with the delta fKfc obtained using a spectrophotometer (0.27 +/- 0.20) and with the Kfc obtained using the blood-corrected gravimetric method (0.32 +/- 0.23). Thus, this new optical system was shown to accurately measure plasma concentration changes in whole blood for physiologic levels of Kfc. The same system can be used with different optical tracers and different source wavelengths to make optical plasma concentration measurements for other physiologic applications.

  16. Measuring coherence of computer-assisted likelihood ratio methods.

    PubMed

    Haraksim, Rudolf; Ramos, Daniel; Meuwly, Didier; Berger, Charles E H

    2015-04-01

    Measuring the performance of forensic evaluation methods that compute likelihood ratios (LRs) is relevant for both the development and the validation of such methods. A framework of performance characteristics categorized as primary and secondary is introduced in this study to help achieve such development and validation. Ground-truth labelled fingerprint data is used to assess the performance of an example likelihood ratio method in terms of those performance characteristics. Discrimination, calibration, and especially the coherence of this LR method are assessed as a function of the quantity and quality of the trace fingerprint specimen. Assessment of the coherence revealed a weakness of the comparison algorithm in the computer-assisted likelihood ratio method used.

  17. Computer assisted screening, correction, and analysis of historical weather measurements

    NASA Astrophysics Data System (ADS)

    Burnette, Dorian J.; Stahle, David W.

    2013-04-01

    A computer program, Historical Observation Tools (HOB Tools), has been developed to facilitate many of the calculations used by historical climatologists to develop instrumental and documentary temperature and precipitation datasets and makes them readily accessible to other researchers. The primitive methodology used by the early weather observers makes the application of standard techniques difficult. HOB Tools provides a step-by-step framework to visually and statistically assess, adjust, and reconstruct historical temperature and precipitation datasets. These routines include the ability to check for undocumented discontinuities, adjust temperature data for poor thermometer exposures and diurnal averaging, and assess and adjust daily precipitation data for undercount. This paper provides an overview of the Visual Basic.NET program and a demonstration of how it can assist in the development of extended temperature and precipitation datasets using modern and early instrumental measurements from the United States.

  18. Measurement of energy distribution in flowing hydrogen microwave plasmas

    NASA Technical Reports Server (NTRS)

    Chapman, R.; Morin, T.; Finzel, M.; Hawley, M. C.

    1985-01-01

    An electrothermal propulsion concept utilizing a microwave plasma system as the mechanism to convert electromagnetic energy into kinetic energy of a flowing gas is investigated. A calorimetry system enclosing a microwave plasma system has been developed to accurately measure the energy inputs and outputs of the microwave plasma system. The rate of energy transferred to the gas can be determined to within + or - 1.8 W from an energy balance around the microwave plasma system. The percentage of the power absorbed by the microwave plasma system transferred to the hydrogen gas as it flows through the system is found to increase with the increasing flow rate, to decrease with the increasing pressure, and to be independent of the absorbed power. An upper bound for the hydrogen gas temperature is estimated from the energy content, heat capacity, and flow rate of the gas stream. A lower bound for an overall heat-transfer coefficient is then calculated, characterizing the energy loss from the hydrogen gas stream to the air cooling of the plasma discharge tube wall. The heat-transfer coefficient is found to increase with the increasing flow rate and pressure and to be independent of the absorbed power. This result indicates that a convective-type mechanism is responsible for the energy transfer.

  19. Plasma flow field measurements downstream of a hollow cathode

    NASA Astrophysics Data System (ADS)

    Farnell, Casey Coffman

    2007-12-01

    The focus of the research described herein is to investigate and characterize the plasma produced downstream of a hollow cathode with the goal of identifying groups of ions and possible mechanisms of their formation within a plasma discharge that might cause erosion, especially with respect to the hollow cathode assembly. In space applications, hollow cathodes are used in electrostatic propulsion devices, especially in ion thrusters and Hall thrusters, to provide electrons to sustain the plasma discharge and neutralize the ion beam. This research is considered important based upon previous thruster life tests that have found erosion occurring on hollow cathode, keeper, and ion optics surfaces exposed to the discharge plasma. This erosion has the potential to limit the life of the thruster, especially during ambitious missions that require ultra long periods of thruster operation. Results are presented from two discharge chamber configurations that produced very different plasma environments. Four types of diagnostics are described that were used to probe the plasma including an emissive probe, a triple Langmuir probe, a remotely located electrostatic analyzer (ESA), and an ExB probe attached to the ESA. In addition, a simulation model was created that correlates the measurements from the direct and remotely located probes.

  20. Isoelectronic line intensity ratios for plasma electron temperature measurement (invited)

    NASA Astrophysics Data System (ADS)

    Marjoribanks, Robin S.; Budnik, Fredric; Kulcsár, Gábor; Zhao, Liang

    1995-01-01

    Strictly speaking, temperature is uniquely defined only in plasmas which are in complete thermodynamic equilibrium. In typical laser-produced plasmas, measurement of electron temperature amounts to a parametrization of some part of the distribution of electron energies, typically inferred from the recombination continuum, or from the ratio of spectral lines that are implicitly dependent on the electron distribution. Where the plasma is highly transient, suffers appreciable opacity, or is subject to a background radiation field, the interpretation of temperature from disparate spectral lines can become untrustworthy. For these complicated plasmas, a conceptually simpler spectral line diagnostic offers great advantages. A technique has been introduced that begins with plasmas that include two elements of similar atomic number, in a known ratio, and compares isoelectronic lines from ions that differ only in their nuclear charge Z, and thus in their ionization potentials χi. Since these two have different values of the same dimensionless parameter Te/χi, the ratio of intensities of isoelectronic lines can be interpreted to determine the temperature Te. The technique and its areas of advantage are described, the applications made to the special problems of laboratories elsewhere are summarized, and this particular progress in application to laser plasmas produced by high-intensity picosecond pulses are reported here.

  1. Measurement Performance of a Computer Assisted Vertebral Motion Analysis System

    PubMed Central

    Davis, Reginald J.; Lee, David C.; Cheng, Boyle

    2015-01-01

    Background Segmental instability of the lumbar spine is a significant cost within the US health care system; however current thresholds for indication of radiographic instability are not well defined. Purpose To determine the performance measurements of sagittal lumbar intervertebral measurements using computerassisted measurements of the lumbar spine using motion sequences from a video-fluoroscopic technique. Study design Sensitivity, specificity, predictive values, prevalence, and test-retest reliability evaluation of digitized manual versus computer-assisted measurements of the lumbar spine. Patient sample A total of 2239 intervertebral levels from 509 symptomatic patients, and 287 intervertebral levels from 73 asymptomatic participants were retrospectively evaluated. Outcome measures Specificity, sensitivity, negative predictive value (NPV), diagnostic accuracy, and prevalence between the two measurement techniques; Measurements of Coefficient of repeatability (CR), limits of agreement (LOA), intraclass correlation coefficient (ICC; type 3,1), and standard error of measurement for both measurement techniques. Methods Asymptomatic individuals and symptomatic patients were all evaluated using both the Vertebral Motion Analysis (VMA) system and fluoroscopic flexion extension static radiographs (FE). The analysis was compared to known thresholds of 15% intervertebral translation (IVT, equivalent to 5.3mm assuming a 35mm vertebral body depth) and 25° intervertebral rotation (IVR). Results The VMA measurements demonstrated greater specificity, % change in sensitivity, NPV, prevalence, and reliability compared with FE for radiographic evidence of instability. Specificity was 99.4% and 99.1% in the VMA compared to 98.3% and 98.2% in the FE for IVR and IVT, respectively. Sensitivity in this study was 41.2% and 44.6% greater in the VMA compared to the FE for IVR and IVT, respectively. NPV was 91% and 88% in the VMA compared to 62% and 66% in the FE for IVR and IVT

  2. Singletip Langmuir Measurements of UW-RWM Plasma

    NASA Astrophysics Data System (ADS)

    Hannum, David; Forest, Cary; Kendrick, Roch

    2009-05-01

    The rotating wall machine is a linear screw-pinch built to study the role of different wall boundary conditions on the resistive wall mode (RWM). Its plasma is created by a hexagonal array of seven electrostatic guns. The guns can be biased to discharge up to 1 kA of current each, firing independently or in tandem. The 20 cm diameter, 1.2 m long plasma column is held in place by a 600 G (max) axial guide field. A singletip Langmuir probe inserted from the opposite end of the chamber yields measurements of Te, ne and Vp in r and z. The density fired from a single gun on the magnetic axis diffuses to the wall as it travels down the column, while the plasma from seven guns condenses in the center. I will present 2D Langmuir profiles and animations of the unbiased plasma column in several density and field configurations; biased plasma current measurements are an ongoing concern.

  3. Measurement realities of current collection in dynamic space plasma environments

    NASA Technical Reports Server (NTRS)

    Szuszczewicz, Edward P.

    1990-01-01

    Theories which describe currents collected by conducting and non-conducting bodies immersed in plasmas have many of their concepts based upon the fundamentals of sheath-potential distributions and charged-particle behavior in superimposed electric and magnetic fields. Those current-collecting bodies (or electrodes) may be Langmuir probes, electric field detectors, aperture plates on ion mass spectrometers and retarding potential analyzers, or spacecraft and their rigid and tethered appendages. Often the models are incomplete in representing the conditions under which the current-voltage characteristics of the electrode and its system are to be measured. In such cases, the experimenter must carefully take into account magnetic field effects and particle anisotropies, perturbations caused by the current collection process itself and contamination on electrode surfaces, the complexities of non-Maxwellian plasma distributions, and the temporal variability of the local plasma density, temperature, composition and fields. This set of variables is by no means all-inclusive, but it represents a collection of circumstances guaranteed to accompany experiments involving energetic particle beams, plasma discharges, chemical releases, wave injection and various events of controlled and uncontrolled spacecraft charging. Here, an attempt is made to synopsize these diagnostic challenges and frame them within a perspective that focuses on the physics under investigation and the requirements on the parameters to be measured. Examples include laboratory and spaceborne applications, with specific interest in dynamic and unstable plasma environments.

  4. [Study of plasma temperature measurements for oxygen discharge].

    PubMed

    Li, Liu-Cheng; Wang, Zeng-Qiang; Li, Gu-Fu; Duo, Li-Ping

    2011-10-01

    A radio-frequency discharge setup was constructed by two shell-shaped copper electrodes and a 30 cm long pyrex glass tube (i. d. = 1.65 cm) to examine the gas temperature of oxygen plasma in electric discharge oxygen iodine laser. The discharge was supplied by a 500 watt, 13.56 MHz radio-frequency power. The gas pressure in the discharge cavity was 1 330 Pa. The temperature of oxygen discharge plasma was measured by using the P branch of O2 (b, v = 0) rotational emission spectrum. Two methods were used to deduce the oxygen gas temperature. They are Boltzman plotting method and computer simulating spectrum method, respectively. Gauss fitting method was used to distinguish spectrum peaks for lower resolution spectrum. The spectrum peak area was used to characterize the optical emission intensity. The gas temperature of oxygen discharge plasma was obtained by Boltzmann plotting method. Alternatively, the optical emission spectrum was simulated by computer modeling with spectrometer slit function which was obtained by He-Ne laser. Consequently, the gas temperature of oxygen plasma was obtained by comparing the computer simulating spectrum and the experimentally observed spectrum according to the least square fitting rule. The measurement results with the two methods agree well. It was concluded that the simple optical technique can be used conveniently in the temperature diagnostics of oxygen radio-frequency discharge plasma.

  5. Two spacecraft measurements of the Martian plasma environment

    NASA Astrophysics Data System (ADS)

    Brain, David; Luhmann, Janet G.; Barabash, Stas; Fedorov, A.; Winningham, D. L.; Acuna, Mario; Frahm, Rudy

    For a period of nearly three years from early 2004 through late 2006, two spacecraft made complementary in situ measurements of the Martian plasma environment. The Mars Global Surveyor magnetometer and electron reflectometer (MGS MAG/ER) measured magnetic fields and suprathermal electrons from an orbit fixed in local time and altitude. The Mars Express Analyzer of Space Plasma and Energetic Atoms (MEX ASPERA-3) measured and still measures ions and suprathermal electrons from a precessing elliptical orbit. MGS lacked an ion instrument, and MEX lacks a magnetometer. Study of the two sets of measurements together provides an opportunity to better understand the complete Martian plasma environment spatially and temporally. We will discuss several advantageous configurations of MEX and MGS, and present examples of each. 'Close conjunctions' are defined as periods when the spacecraft passed very close to each other, within an ion gyroradius or inertial length, allowing examination of more complete particle and field measurements in a given region. 'Delay conjunctions' are defined as instances when the two spacecraft passed through the same region of space separated by a time delay, allowing examination of the evolution of electron distributions in a given region. 'Flux tube conjunctions' are defined as instances when it was likely that the two spacecraft occupied the same flux tube some distance apart, allowing study of the spatial evolution of plasma as it moves along a flux tube. We will also present examples of other fortuitous configurations of MEX and MGS, such as times when they were on opposite sides of a given plasma boundary.

  6. Tensile adhesion test measurements on plasma-sprayed coatings

    NASA Technical Reports Server (NTRS)

    Berndt, C. C.

    1986-01-01

    Adhesion measurements on plasma-sprayed coatings are briefly studied, including a critical analysis of the experimental scatter for duplicate tests. The application of a simple method which presents adhesion strength data in a fracture mechanics perspective is demonstrated. Available data are analyzed in a way which suggests an approach to finding the overall defect contribution to reducing the apparent strength of coatings.

  7. Electrical Conductivity Measurements in Strongly Coupled Metal Plasmas

    NASA Astrophysics Data System (ADS)

    Desilva, Alan

    1998-11-01

    The coupling parameter Γ=e^2/akT, where a is the mean ion-ion separation, expresses the ratio of the mean potential energy of ions in a plasma to their mean kinetic energy. Plasma is said to be strongly coupled when Γ is greater than unity. Transport properties of strongly coupled plasmas are of interest in the study of the structure of dense astrophysical objects and gaseous planetary interiors, as well as in arcs and laser-produced plasmas. We are attempting to measure the electrical conductivity of strongly coupled metal plasmas (copper, tungsten and aluminum) in the temperature range 8-30 kK, in a density range from about 1/2 solid density down to about 10-3 times solid density. They may have coupling parameters Γ ranging from as high as 100 down to unity Plasmas are created by rapid vaporization of metal wire in a glass capillary or in a water bath which act as a tamper, slowing the expansion rate. The effect of the tamper is to force the interior pressure of the plasma to be fairly uniform. Streak photography serves to determine the growth of the plasma radius in time, allowing determination of mean density. Temperature is deduced from the measured energy input in conjunction with an equation of state from the LANL sesame database(SESAME: The Los Alamos National Laboratory Equation of State Database, Report No. LA-UR-92-3407, Ed. S. P. Lyon and J. D. Johnson, Group T-1 (unpublished)), and a brightness temperature may be obtained from radiation measurements. The column resistance is simply determined from time-resolved voltage and current measurements. For temperatures less than about 14,000K, as density decreases from the highest values measured, the conductivity falls roughly as the cube of density, reaches a minimum, and subsequently rises to approach the Spitzer prediction at low density. The rate of change of conductivity with density becomes less rapid as temperature increases, and the minimum becomes less pronounced, disappearing altogether above

  8. The Plasma Instrument for Magnetic Sounding (PIMS): Enabling Required Plasma Measurements for the Exploration of Europa

    NASA Astrophysics Data System (ADS)

    Westlake, J. H.; McNutt, R. L., Jr.; Kasper, J. C.; Case, A. W.; Rymer, A. M.; Khurana, K. K.; Stevens, M. L.; Jia, X.; Slavin, J. A.; Paty, C. S.; Smith, H. T.; Kivelson, M.; Saur, J.; Krupp, N.; Roussos, E.; Korth, H.

    2015-12-01

    Europa exists in a complicated plasma environment where the tilt of Jupiter's magnetic field and rapid rotation rate leads to a dynamic interaction with Europa's ionospheric plasma. While understanding this plasma interaction is interesting in its own right, it is crucial for successfully magnetically sounding Europa's subsurface ocean. . In magnetic sounding, currents induced in Europa by the changing Jovian plasma produce a detectable secondary magnetic field that reflects properties of Europa's subsurface ocean such as depth and conductivity. This technique was successfully employed with Galileo observations of Europa to demonstrate that Europa indeed has a subsurface ocean containing more liquid water than Earth's oceans. While these Galileo observations contributed to the renewed interest in Europa, the results raised major questions that remain unanswered, in part due to the large uncertainties in the ice shell thickness, ocean depth, and ocean salinity due to limitations in the observations. Here we present the scientific goals of the Plasma Instrument for Magnetic Sounding (PIMS), one of the 9 instruments selected for the Europa Multiple Flyby Mission. We specifically address how PIMS plasma measurements will transform the accuracy of magnetic sounding of Europa's subsurface oceans. We also present synergistic science with other Europa instrumentation such as the ultraviolet spectrometer, mass spectrometer, and the radar.

  9. Plasma-assisted Molecular Beam Epitaxy Growth and Properties of Tin Oxide

    NASA Astrophysics Data System (ADS)

    Tsai, Min-Ying

    Currently, transparent conducting oxides (TCOs) ZnO, SnO2, In2O3, and Ga2O3 are widely used in electrical and optoelectronic devices. With a wide-bandgap of 3.6 eV transparent to the visible and near-UV spectrum, SnO2, has generated many interests not only due to the curiosity of fundamental research on material science but also potential technological uses in the industry. This dissertation focuses on the development of SnO2 epitaxy by plasma-assisted molecular beam epitaxy (PAMBE). The detailed growth mechanism, physical properties and electrical doping studies will be addressed along with the application as a transparent contact for GaN-based LEDs. High-quality single-crystalline SnO2 films were grown on TiO 2 in the Volmer--Weber growth mode. A growth rate diagram was constructed by the dependence of growth rate on tin flux under a constant oxygen BEP. This growth rate diagram consisted of two growth regimes: an increased growth rate under an oxygen-rich regime and a decreased growth rate under a tin-rich regime. The decreased growth rate was due to the formation of volatile SnO. No SnO2 growth was observed when the impinging tin flux was larger than twice the stoichiometric flux. A detailed study on transport properties was discussed to evaluate the origin of n-type conductivity in SnO2. Lowest electron concentration was measured on the oxygen-rich grown sample. Based on the evolution of the electron concentrations before and after annealing, oxygen vacancies were considered as the dominant donors in our SnO2 films. Controllable electrical conductivity by Ga-doping was performed. The decrease of electron concentrations with increasing Ga concentrations indicated Ga acted as a compensation center in SnO2. A semi-insulating SnO 2 film was achieved with the Ga concentration of 1.5 x10 18 cm-3. A deterioration of crystalline quality was observed beyond this concentration due to the formation of Ga2O 3 secondary phases. Finally, highly conductive Sb-doped SnO2 (ATO

  10. Unfolding plasma density from cylindrical monopole impedance measurements in ionosphere

    NASA Astrophysics Data System (ADS)

    Kiraga, A.

    2003-04-01

    Several common problems occur in measurement techniques and interpretation of plasma natural emissions and impedance data. Antenna characteristics are of prime importance in equivalent circuit analysis. Spacecraft - plasma interaction contributes to variability of equivalent circuit impedances and e.m.f. components and imposes constrains on usefulness of experimental data. In order to have independent, built in estimate of local plasma frequency and to get deeper insight into properties of equivalent circuit for wave diagnostics, impedance measurement was integrated with radio receivers on the ACTIVE, APEX and CORONAS satellites. Impedance measurements of 7.5m long monopole were performed in frequency range .1-10MHz with the frequency step of 50kHz, in voltage divider configuration. Due to high inclination of 82.5deg and altitude range of 500-3000km, data from very different plasmas were collected. Data can be split into quasi normal, disturbed and very disturbed measurements. Equivalent circuit structure evolved in attempt to match even very disturbed measurements. For quasi normal measurements, satisfactory matching is obtained with computed gyrofrequency fc and fitted plasma frequency fn, stray capacitance Cs and capacitance Cv of phenomenological vacuum sheath. With formulas for monopole impedance in cold magnetoplasma, two basic pectral structures are explained. For sufficiently magnetized plasma (roughly fn/fc<2 if Cs=20pF), circuit parallel resonance frequency Fr falls into upper hybrid band (max(fn,fc),fu), resonance amplitude is reduced by high antenna resistance and horn like absolute maximum points fu. For values of fn/fc ratio, greater then critical, Fr is less than fn and broad absolute maximum at Fr follows from low antenna resistance. Further increase of fn/fc results in increasing lag of Fr behind fn. Critical ratio fn/fc increases with decreasing stray capacitance Cs. It follows from data analysis that stray capacitance may change in flight, at

  11. Measurement Performance of a Computer Assisted Vertebral Motion Analysis System.

    PubMed

    Davis, Reginald J; Lee, David C; Wade, Chip; Cheng, Boyle

    2015-01-01

    Segmental instability of the lumbar spine is a significant cost within the US health care system; however current thresholds for indication of radiographic instability are not well defined. To determine the performance measurements of sagittal lumbar intervertebral measurements using computerassisted measurements of the lumbar spine using motion sequences from a video-fluoroscopic technique. Sensitivity, specificity, predictive values, prevalence, and test-retest reliability evaluation of digitized manual versus computer-assisted measurements of the lumbar spine. A total of 2239 intervertebral levels from 509 symptomatic patients, and 287 intervertebral levels from 73 asymptomatic participants were retrospectively evaluated. Specificity, sensitivity, negative predictive value (NPV), diagnostic accuracy, and prevalence between the two measurement techniques; Measurements of Coefficient of repeatability (CR), limits of agreement (LOA), intraclass correlation coefficient (ICC; type 3,1), and standard error of measurement for both measurement techniques. Asymptomatic individuals and symptomatic patients were all evaluated using both the Vertebral Motion Analysis (VMA) system and fluoroscopic flexion extension static radiographs (FE). The analysis was compared to known thresholds of 15% intervertebral translation (IVT, equivalent to 5.3mm assuming a 35mm vertebral body depth) and 25° intervertebral rotation (IVR). The VMA measurements demonstrated greater specificity, % change in sensitivity, NPV, prevalence, and reliability compared with FE for radiographic evidence of instability. Specificity was 99.4% and 99.1% in the VMA compared to 98.3% and 98.2% in the FE for IVR and IVT, respectively. Sensitivity in this study was 41.2% and 44.6% greater in the VMA compared to the FE for IVR and IVT, respectively. NPV was 91% and 88% in the VMA compared to 62% and 66% in the FE for IVR and IVT, respectively. Prevalence was 12.3% and 11.9% for the VMA compared to 6.1% and 5

  12. First fusion proton measurements in TEXTOR plasmas using activation technique

    SciTech Connect

    Bonheure, G.; Wassenhove, G. Van; Mlynar, J.; Hult, M.; Gonzalez de Orduna, R.; Lutter, G.; Vermaercke, P.; Huber, A.; Schweer, B.; Esser, G.; Biel, W.

    2012-10-15

    MeV particle loss measurements from fusion plasmas, in particular alpha particles, remain difficult in large fusion devices and further R and D is needed for ITER. This paper describes the first attempt to measure 3 MeV escaping fusion protons emitted from TEXTOR tokamak plasmas using activation technique. This technique was successfully demonstrated, initially, in 2006 on the JET tokamak. An ion camera equipped with a collimator and several types of activation detectors was installed inside the TEXTOR vacuum vessel to perform these measurements. After irradiation, the detectors were analyzed using ultra low level gamma-ray spectrometry at the HADES underground laboratory. 3 MeV escaping fusion protons were detected in larger number -{approx}6 times more - compared to earlier measurements using this technique on JET. Another major progress was the reduction of the cooling time by a factor of 50, which made possible to detect radionuclides with half-life of less than 90 min.

  13. First fusion proton measurements in TEXTOR plasmas using activation technique.

    PubMed

    Bonheure, G; Mlynar, J; Van Wassenhove, G; Hult, M; González de Orduña, R; Lutter, G; Vermaercke, P; Huber, A; Schweer, B; Esser, G; Biel, W

    2012-10-01

    MeV particle loss measurements from fusion plasmas, in particular alpha particles, remain difficult in large fusion devices and further R&D is needed for ITER. This paper describes the first attempt to measure 3 MeV escaping fusion protons emitted from TEXTOR tokamak plasmas using activation technique. This technique was successfully demonstrated, initially, in 2006 on the JET tokamak. An ion camera equipped with a collimator and several types of activation detectors was installed inside the TEXTOR vacuum vessel to perform these measurements. After irradiation, the detectors were analyzed using ultra low level gamma-ray spectrometry at the HADES underground laboratory. 3 MeV escaping fusion protons were detected in larger number -~6 times more--compared to earlier measurements using this technique on JET. Another major progress was the reduction of the cooling time by a factor of 50, which made possible to detect radionuclides with half-life of less than 90 min.

  14. First fusion proton measurements in TEXTOR plasmas using activation techniquea)

    NASA Astrophysics Data System (ADS)

    Bonheure, G.; Mlynar, J.; Wassenhove, G. Van; Hult, M.; González de Orduña, R.; Lutter, G.; Vermaercke, P.; Huber, A.; Schweer, B.; Esser, G.; Biel, W.

    2012-10-01

    MeV particle loss measurements from fusion plasmas, in particular alpha particles, remain difficult in large fusion devices and further R&D is needed for ITER. This paper describes the first attempt to measure 3 MeV escaping fusion protons emitted from TEXTOR tokamak plasmas using activation technique. This technique was successfully demonstrated, initially, in 2006 on the JET tokamak. An ion camera equipped with a collimator and several types of activation detectors was installed inside the TEXTOR vacuum vessel to perform these measurements. After irradiation, the detectors were analyzed using ultra low level gamma-ray spectrometry at the HADES underground laboratory. 3 MeV escaping fusion protons were detected in larger number -˜6 times more - compared to earlier measurements using this technique on JET. Another major progress was the reduction of the cooling time by a factor of 50, which made possible to detect radionuclides with half-life of less than 90 min.

  15. Measurements by the plasma diagnostics package on STS-3

    NASA Technical Reports Server (NTRS)

    Shawhan, S. D.; Murphy, G. B.

    1982-01-01

    A comprehensive set of measurements about the orbiter environment are provided by the plasma diagnostics package (PDP). Ion and electron particle densities, energies, and spatial distribution functions; ion mass for identification of particular molecular ion species; and magnetic fields, electric fields and electromagnetic waves over a broad frequency range are studied. Shuttle environmental measurements will be made both on the pallet and, by use of the remote manipulator system (RMS), the PDP will be maneuvered in and external to the bay area to continue environmental measurements and to carry on a joint plasma experiment with the Utah State University fast-pulsed electron generator. Results of orbiter environment EMI measurements and S-band field strengths as well as preliminary results from wake search operations indicating wake boundary identifiers are reported.

  16. Laser Induced Fluorescence Measurement of Plasma Hole in a Helium Plasma with Argon Impurity

    NASA Astrophysics Data System (ADS)

    Yoshimura, Shinji; Okamoto, Atsushi; Tanaka, Masayoshi

    2008-11-01

    A singular vortex with density cavity in its center (plasma hole) has been observed in a magnetized helium plasma. The ion flow velocity field of the plasma hole measured with a directional Langmuir probe shows a monopole vortex with radial flow. In order to measure more precise ion flow velocity field, we have developed a laser induced fluorescence (LIF) Doppler spectroscopy system for the Hyper-I device at the National Institute for Fusion Science, Japan. Since a suitable LIF scheme at visible wavelength is available for argon ions, we employed it to determine the flow velocity field of the plasma hole in a helium plasma in which a small amount of argon gas is introduced as an impurity. An ArII metastable state is excited by a tunable dye laser operating at 611.5nm and the fluorescence decay at 461.0nm is observed by a photomultiplier tube with an optical filter. By sweeping the wavelength of the dye laser, we can obtain information about the Doppler-shifted velocity distribution function of the excited ions. By changing the path of laser beam and the position of collection optics, we can obtain both azimuthal and radial ion flow velocities.

  17. Cassini measurements of cold plasma in the ionosphere of Titan.

    PubMed

    Wahlund, J E; Boström, R; Gustafsson, G; Gurnett, D A; Kurth, W S; Pedersen, A; Averkamp, T F; Hospodarsky, G B; Persoon, A M; Canu, P; Neubauer, F M; Dougherty, M K; Eriksson, A I; Morooka, M W; Gill, R; André, M; Eliasson, L; Müller-Wodarg, I

    2005-05-13

    The Cassini Radio and Plasma Wave Science (RPWS) Langmuir probe (LP) sensor observed the cold plasma environment around Titan during the first two flybys. The data show that conditions in Saturn's magnetosphere affect the structure and dynamics deep in the ionosphere of Titan. The maximum measured ionospheric electron number density reached 3800 per cubic centimeter near closest approach, and a complex chemistry was indicated. The electron temperature profiles are consistent with electron heat conduction from the hotter Titan wake. The ionospheric escape flux was estimated to be 10(25) ions per second.

  18. Floating potential measurements in plasmas: From dust to spacecraft

    NASA Astrophysics Data System (ADS)

    Beadles, R.; Wang, X.; Horányi, M.

    2017-02-01

    We present measurements of the floating potential of spherical probes, used as a model of a dust particle or a spacecraft, immersed in plasmas with a wide range of Debye lengths. Our experimental results verified the theoretical prediction that the probe floating potential is a function of the Debye length. It is shown that, in an argon plasma with the ion to electron temperature ratio ˜0.01, the magnitude of the floating potential is approximately doubled when the Debye length is changed from larger to smaller than the radius of the probe.

  19. Growth Optimization of III-N Electronic Devices by Plasma-Assisted Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Ahmadi, Elaheh

    InAlN has received significant attention due to its great potential for electronic and optoelectronic applications. In particular, In 0.18Al0.82N presents the advantage of being lattice-matched to GaN and simultaneously exhibiting a high spontaneous polarization charge, making In0.18 Al0.82N attractive for use as the barrier layer in high-electron-mobility transistors (HEMTs). However, in the case of InAlN growth by plasma-assisted molecular beam epitaxy (PAMBE), a strong non-uniformity in the in-plane In distribution was observed for both N-face and metal-face In0.18Al 0.82N. This compositional inhomogeneity manifests itself as a columnar microstructure with AlN-rich cores (5-10 nm in width) and InN-rich intercolumn boundaries. Because of the large differences between the bandgaps and polarization of InN and AlN, this non-uniformity in InAlN composition could be a source of scattering, leading to mobility degradation in HEMTs. In this work, the growth conditions for high quality lattice-matched InAlN layers on free-standing GaN substrates were explored by plasma-assisted molecular beam epitaxy (PAMBE) in the N-rich regime. The microstructure of N-face InAlN layers, lattice-matched to GaN, was investigated by scanning transmission electron microscopy and atom probe tomography. Microstructural analysis showed an absence of the lateral composition modulation that was previously observed in InAlN films grown by PAMBE. Using same growth conditions for InAlN layer, N-face GaN/AlN/GaN/InAlN high-electron-mobility transistors with lattice-matched InAlN back barriers were grown directly on SiC. A room temperature two-dimensional electron gas (2DEG) mobility of 1100cm2 V-1s-1 and 2DEG sheet charge density of 1.9 x1013 cm 2 was measured on these devices. However, the threading dislocation density (TDD) of GaN grown directly on SiC by PAMBE (≈2 x10 10 cm-2 ) is two orders of magnitude higher than GaN grown by MOCVD on SiC or sapphire (≈5 x10 8 cm-2). This high TDD can

  20. Direct current dielectric barrier assistant discharge to get homogeneous plasma in capacitive coupled discharge

    SciTech Connect

    Du, Yinchang; Li, Yangfang; Cao, Jinxiang; Liu, Yu; Wang, Jian; Zheng, Zhe

    2014-06-15

    In this paper, we propose a method to get more homogeneous plasma in the geometrically asymmetric capacitive coupled plasma (CCP) discharge. The dielectric barrier discharge (DBD) is used for the auxiliary discharge system to improve the homogeneity of the geometrically asymmetric CCP discharge. The single Langmuir probe measurement shows that the DBD can increase the electron density in the low density volume, where the DBD electrodes are mounted, when the pressure is higher than 5 Pa. By this manner, we are able to improve the homogeneity of the plasma production and increase the overall density in the target volume. At last, the finite element simulation results show that the DC bias, applied to the DBD electrodes, can increase the homogeneity of the electron density in the CCP discharge. The simulation results show a good agreement with the experiment results.

  1. Spectroscopic temperature measurements of non-equilibrium plasmas

    SciTech Connect

    Back, C.A.; Glenzer, S.H.; Lee, R.W.; MacGowan, B.J.

    1996-04-24

    The characterization of laser-produced plasmas has required the application of spectroscopic techniques to non-standard conditions where kinetics models have not been extensively tested. The plasmas are produced by the Nova laser for the study of inertial confinement fusion, can be mm in size, and evolve on sub-nanosecond time scales. These targets typically achieve electron temperatures from 2-4 keV and electron densities of 10{sup 20}-10{sup 22} cm{sup {minus}3}. The authors have measured the electron temperature of two types of targets: bags of gas and hohlraums, Au cylinders with laser entrance holes in the flat ends. By comparing data from different targets, they examine the time-dependence of spectroscopic plasma diagnostics.

  2. [Plasma metanephrine measurements make the diagnosis of pheochromocytoma easier].

    PubMed

    Friberg, P

    1998-05-20

    A study where plasma metanephrine and normetanephrine concentrations in 51 patients with hypertension and 62 healthy normotensives were compared with those in 52 patients with histologically confirmed phaeochromocytoma showed measurement of the two variables to constitute a test that reliably excludes the presence of phaeochromocytoma in cases where both values are normal. Other currently available tests (e.g., plasma catecholamine assay) can yield false-negative results in some patients with the tumour, and thus do not reliably exclude its presence in unaffected patients. Accordingly, as a missed diagnosis can have disastrous consequences for the patient, hitherto the exclusion of phaeochromocytoma has typically entailed multiple and repeated tests which are time-consuming and costly. The advantage of the plasma metanephrine-normetanephrine test is that, as it does not yield false-negative results, a negative test result reliably excludes the presence of phaeochromocytoma in suspected cases, and no further tests are necessary.

  3. Electron temperature and density measurements of laser induced germanium plasma

    SciTech Connect

    Shakeel, Hira; Arshad, Saboohi; Haq, S. U. Nadeem, Ali

    2016-05-15

    The germanium plasma produced by the fundamental harmonics (1064 nm) of Nd:YAG laser in single and double pulse configurations have been studied spectroscopically. The plasma is characterized by measuring the electron temperature using the Boltzmann plot method for neutral and ionized species and electron number density as a function of laser irradiance, ambient pressure, and distance from the target surface. It is observed that the plasma parameters have an increasing trend with laser irradiance (9–33 GW/cm{sup 2}) and with ambient pressure (8–250 mbar). However, a decreasing trend is observed along the plume length up to 4.5 mm. The electron temperature and electron number density are also determined using a double pulse configuration, and their behavior at fixed energy ratio and different interpulse delays is discussed.

  4. Current from a dilute plasma measured through holes in insulators

    NASA Technical Reports Server (NTRS)

    Grier, N. T.; Domitz, S.

    1975-01-01

    The current collected from a plasma through holes in insulated electrodes was measured. Holes of 0.051- and 2.54-cm diameters in Kapton H film and plasma number densities of 100 and 10,000 electrons/cu cm were used. The current collected by bare electrodes, that is, electrodes with no surrounding insulation, is also presented. For all the samples the current at a given voltage was a function of the surrounding insulator area rather than of the hole size or the underlying electrode size. In addition, at the low plasma density the I-V characteristic showed very steep rises for voltages below 1 kV. In one case the current jumped by a factor of approximately 70 to 200 V. Results are given for positive biases to 10 kV. For negative biases, sparking prevented testing most samples to the 10-kV limit.

  5. A microwave interferometer for small and tenuous plasma density measurements.

    PubMed

    Tudisco, O; Lucca Fabris, A; Falcetta, C; Accatino, L; De Angelis, R; Manente, M; Ferri, F; Florean, M; Neri, C; Mazzotta, C; Pavarin, D; Pollastrone, F; Rocchi, G; Selmo, A; Tasinato, L; Trezzolani, F; Tuccillo, A A

    2013-03-01

    The non-intrusive density measurement of the thin plasma produced by a mini-helicon space thruster (HPH.com project) is a challenge, due to the broad density range (between 10(16) m(-3) and 10(19) m(-3)) and the small size of the plasma source (2 cm of diameter). A microwave interferometer has been developed for this purpose. Due to the small size of plasma, the probing beam wavelength must be small (λ = 4 mm), thus a very high sensitivity interferometer is required in order to observe the lower density values. A low noise digital phase detector with a phase noise of 0.02° has been used, corresponding to a density of 0.5 × 10(16) m(-3).

  6. Plasma resistivity measurements in the Wisconsin levitated octupole

    SciTech Connect

    Brouchous, D. A.

    1980-11-01

    Resistivity measurements parallel to the magnetic field were made on gun injected plasmas ranging in density from 10/sup 9/cm/sup -3/ to 10/sup 1/parallelcm/sup -3/ in the Wisconsin levitated octupole with toroidal and poloidal magnetic fields. The 10/sup 9/cm/sup -3/ plasma was collisionless with lambda/sub mfp/ > 100 mirror lengths, had T/sub e/ = 10 eV, T/sub i/ = 30 eV and was found to have anomalous resistivity scaling like eta = ..sqrt..T/sub e//n/sub e/ when E/sub parallel/ > E/su c/ is the Dreicer critical field. The 10/sup 12/cm/sup -3/ plasma was collisional with lambda/sub mfp/ < mirror length, had T/sub e/ = T/sub i/ approx. = .2 eV and was found to have Spitzer resistivity when E/sub parallel/ < E/sub c/.

  7. A microwave interferometer for small and tenuous plasma density measurements

    SciTech Connect

    Tudisco, O.; Falcetta, C.; De Angelis, R.; Florean, M.; Neri, C.; Mazzotta, C.; Pollastrone, F.; Rocchi, G.; Tuccillo, A. A.; Lucca Fabris, A.; Manente, M.; Ferri, F.; Tasinato, L.; Trezzolani, F.; Accatino, L.; Selmo, A.

    2013-03-15

    The non-intrusive density measurement of the thin plasma produced by a mini-helicon space thruster (HPH.com project) is a challenge, due to the broad density range (between 10{sup 16} m{sup -3} and 10{sup 19} m{sup -3}) and the small size of the plasma source (2 cm of diameter). A microwave interferometer has been developed for this purpose. Due to the small size of plasma, the probing beam wavelength must be small ({lambda}= 4 mm), thus a very high sensitivity interferometer is required in order to observe the lower density values. A low noise digital phase detector with a phase noise of 0.02 Degree-Sign has been used, corresponding to a density of 0.5 Multiplication-Sign 10{sup 16} m{sup -3}.

  8. Erasure temperature measurements of heat assisted magnetic recording media

    NASA Astrophysics Data System (ADS)

    Chen, Y. J.; Yang, H. Z.; Leong, S. H.; Cher, K. M.; Hu, J. F.; Sethi, P.; Lew, W. S.

    2015-05-01

    For heat assisted magnetic recording (HAMR) media development, measurement of erasure temperature (Te) is interesting and important for practical HAMR testing and applications. Here, we present an investigation on Te measurements of L10 ordered FePt granular HAMR media made using a Laser Heating (LH) method on a home-built HAMR write test system versus that from a bulk heating approach. The HAMR write test system provides HAMR writing, micro-MOKE (magneto-optical Kerr effect) signal detection, and MOKE imaging functions at the same testing spot in one single system. Magnetic force microscopy (MFM) and magnetic Kerr microscopy observations of the scanning laser induced degradation/erasure/demagnetization of the pre-recorded magnetic patterns on disk media (over a wide area of a few hundreds of μm2) show that the magnetic (MFM and Kerr signal) amplitude of the pre-recorded magnetic patterns decreases slowly with increasing laser power (Pw) (/temperature rise) for Pw ≲ 66 mW and then drops sharply to nearly zero for Pw ≥ ˜72 mW (the laser power corresponding to complete thermal erasure when the media temperature is ˜Te). It was further found that this trend of magnetic amplitude reduction with increased Pw is similar to that from magnetic amplitude decrease of pre-recorded magnetic patterns with increased bulk heating temperature. The temperature for complete erasure at laser power, Pw = 72 mW for the LH method, corresponds therefore to ˜650 K (≈Te) for the bulk heating methods. Besides fast measurement, LH (as a comparable and viable approach for erasure measurement) is dynamic, localized, and has time scales closer to practical HAMR situation.

  9. Measurements of the Motion of Plasma Filaments in a Plasma Ball

    SciTech Connect

    Campanell, M.; Laird, J.; Provost, T.; Vasquez, S.; Zweben, S. J.

    2010-01-26

    Measurements were made of the motion of the filamentary structures in a plasma ball using high speed cameras and other optical detectors. These filaments traverse the ball radially at ~106 cm/sec at the driving frequency of ~26 kHz, and drift upward through the ball at ~1 cm/sec. Varying the applied high voltage and frequency caused the number, length, and diameter of the filaments to change. A custom plasma ball was constructed to observe the effects of varying gas pressure and species on the filament structures.

  10. Spectroscopic Measurements of Radio Frequency Plasmas in Supercritical Fluids

    SciTech Connect

    Maehara, Tsunehiro; Iwamae, Atsushi; Kawashima, Ayato

    2010-10-29

    Spectroscopic measurements of radio frequency (rf) plasma were performed under high pressure CO{sub 2} conditions (5 and 7 MPa) and supercritical (sc)CO{sub 2} conditions (8-20 MPa). The temperatures evaluated from C{sub 2} Swan bands increased from 3600 K to 4600 K with increasing pressure. The broadening and shifting of the O I line profile ({approx}777 nm) of rf plasma was observed under scCO{sub 2} conditions. The width of the line profile increased with increasing pressure. The reason for the broadening and shifting is still unclear because the present theory used to explain them is not valid for such high pressure conditions. Further, the broadening of the Ar I line profile ({approx}811.5 nm) in rf plasmas was observed under atmospheric Ar (0.1 MPa), high pressure Ar conditions (1-4 MPa), and scAr condition (5 MPa); the observation of the O I line profile in CO{sub 2} plasmas is difficult in this pressure range owing to its weak intensity therein. Similar to the case of the O I line in CO{sub 2} plasmas, the reason for the broadening of the Ar I line profile at 5 MPa is unclear.

  11. Alpha-particle Measurements Needed for Burning Plasma Experiments

    SciTech Connect

    Kenneth M. Young

    2001-09-26

    The next major step in magnetic fusion studies will be the construction of a burning plasma (BP) experiment where the goals will be to achieve and understand the plasma behavior with the internal heating provided by fusion-generated alpha particles. Two devices with these physics goals have been proposed: the International Thermonuclear Experimental Reactor (ITER) and the Fusion Ignition Research Experiment (FIRE). Extensive conceptual design work for the instrumentation to try to meet the physics demands has been done for these devices, especially ITER. This article provides a new look at the measurements specifically important for understanding the physics aspects of the alpha particles taking into account two significant events. The first is the completion of physics experiments on the Joint European Torus (JET) and the Tokamak Fusion Test Reactor (TFTR) with deuterium-tritium fueling with the first chances to study alpha physics and the second is the realization that relatively compact plasmas, making use of advanced tokamak plasma concepts, are the most probable route to burning plasmas and ultimately a fusion reactor.

  12. Low energy ion distribution measurements in Madison Symmetric Torus plasmas

    SciTech Connect

    Titus, J. B. Mezonlin, E. D.; Johnson, J. A.

    2014-06-15

    Charge-exchange neutrals contain information about the contents of a plasma and can be detected as they escape confinement. The Florida A and M University compact neutral particle analyzer (CNPA), used to measure the contents of neutral particle flux, has been reconfigured, calibrated, and installed on the Madison Symmetric Torus (MST) for high temperature deuterium plasmas. The energy range of the CNPA has been extended to cover 0.34–5.2 keV through an upgrade of the 25 detection channels. The CNPA has been used on all types of MST plasmas at a rate of 20 kHz throughout the entire discharge (∼70 ms). Plasma parameter scans show that the ion distribution is most dependent on the plasma current. Magnetic reconnection events throughout these scans produce stronger poloidal electric fields, stronger global magnetic modes, and larger changes in magnetic energy all of which heavily influence the non-Maxwellian part of the ion distribution (the fast ion tail)

  13. Measurement and characterization of angiotensin peptides in plasma

    SciTech Connect

    Hermann, K.; Ganten, D.; Unger, T.; Bayer, C.; Lang, R.E.

    1988-06-01

    We report a method for the extraction of angiotensin peptides from plasma with a mixture of acetone, 1 mol/L HCl, and water (40/1/5 by vol). The method is highly reproducible for the measurement of angiotensin I and angiotensin II in small sample volumes, with analytical recoveries of about 80% for both peptides. We investigated the influence of sample handling and found a standard procedure for blood collection, plasma preparation, and extraction was essential. The method was used to measure angiotensin I and II in rat and human plasma. In rat plasma, the mean (+/- SEM) concentrations of angiotensin I and angiotensin II were determined to be 67 (+/- 8) and 14 (+/- 1) pmol/L (n = 10), respectively. Neither angiotensin I nor angiotensin II was detectable 24 h after bilateral nephrectomy. Acute oral administration of the converting-enzyme inhibitor ramipril caused a significant increase of angiotensin I from 85 (+/- 6) to 257 (+/- 33) pmol/L (n = 10; P less than 0.001) and a significant decrease of angiotensin II from 12 (+/- 1) to 7 (+/- 0.4) pmol/L in rat plasma (n = 9; P less than 0.001). In human plasma, angiotensin I and angiotensin II values of 21 (+/- 1) and 6.6 (+/- 0.5) pmol/L (n = 10) were found. A single oral dose of the diuretic furosemide increased angiotensin I significantly from 21 (+/- 1) to 32 (+/- 1.7) pmol/L (n = 5); P less than 0.001), whereas angiotensin II remained unchanged, 6.6 (+/- 0.5) vs 6.4 (+/- 0.4) pmol/L (n = 5). Extracted peptides could be identified as (IIe5)-angiotensin I and (IIe5)-angiotensin II by HPLC in combination with specific radioimmunoassays for angiotensin I and angiotensin II.

  14. Plasma drug concentrations and physiological measures in 'dance party' participants.

    PubMed

    Irvine, Rodney J; Keane, Michael; Felgate, Peter; McCann, Una D; Callaghan, Paul D; White, Jason M

    2006-02-01

    The increasing use of (+/-) 3,4-methylenedioxymethamphetamine (MDMA) in the setting of large dance parties ('raves') and clubs has been the source of some concern, because of potential acute adverse events, and because animal studies suggest that MDMA has the potential to damage brain serotonin (5-HT) neurons. However, it is not yet known whether MDMA, as used in the setting of dance parties, leads to plasma levels of MDMA that are associated with toxicity to 5-HT neurons in animals. The present study sought to address this question. Plasma MDMA concentrations, vital signs, and a variety of blood and urine measures were obtained prior to, and hours after, individuals attended a dance party. After the dance party, subjects were without clinical complaints, had measurable amounts of residual MDMA in plasma, and nearly half of the subjects also tested positive for methamphetamine, another amphetamine analog that has been shown to have 5-HT neurotoxic potential in animals. Plasma concentrations of MDMA did not correlate with self-reported use of 'ecstasy' and, in some subjects, overlapped with those that have been associated with 5-HT neurotoxicity in non-human primates. Additional subjects were likely to have had similar concentrations while at the dance party, when one considers the reported time of drug ingestion and the plasma half-life of MDMA in humans. Hematological and biochemical analyses were generally unremarkable. Moderate increases in blood pressure, heart rate and body temperature were observed in the subjects with the highest MDMA plasma concentrations. These findings are consistent with epidemiological findings that most people who use MDMA at dance parties do not develop serious clinical complications, and suggest that some of these individuals may be at risk for developing MDMA-induced toxicity to brain serotonin neurons.

  15. Visible Light Photocatalysis with Nitrogen-Doped Titanium Dioxide Nanoparticles Prepared by Plasma Assisted Chemical Vapor Deposition

    SciTech Connect

    Buzby,S.; Barakat, M.; Lin, H.; Ni, C.; Rykov, S.; Chen, J.; Shah, S.

    2006-01-01

    Nitrogen-doped TiO{sub 2} nanoparticles were synthesized via plasma assisted metal organic chemical vapor deposition. Nitrogen dopant concentration was varied from 0 to 1.61 at. %. The effect of nitrogen ion doping on visible light photocatalysis has been investigated. Samples were analyzed by various analytical techniques such as x-ray diffraction, transmission electron microscopy, x-ray photoelectron spectroscopy, and near-edge x-ray absorption fine structure. Titanium tetraisopropoxide was used as the titanium precursor, while rf-plasma-decomposed ammonia was used as the source for nitrogen doping. The N-doped TiO{sub 2} nanoparticles were deposited on stainless steel mesh under a flow of Ar and O2 gases at 600 {sup o}C in a tube reactor. The photocatalytic activity of the prepared N-doped TiO{sub 2} samples was tested by the degradation of 2-chlorophenol (2-CP) in an aqueous solution using a visible lamp equipped with an UV filter. The efficiency of photocatalytic oxidation of 2-CP was measured using high performance liquid chromatography. Results obtained revealed the formation of N-doped TiO{sub 2} samples as TiO{sub 2-x}N{sub x}, and a corresponding increase in the visible light photocatalytic activity.

  16. Heat flux measurement in a high enthalpy plasma flow

    NASA Astrophysics Data System (ADS)

    Löhle, Stefan; Battaglia, Jean-Luc; Gardarein, Jean-Laurent; Jullien, Pierre; van Ootegem, Bruno

    2008-11-01

    It is a widely used approach to measure heat flux in harsh environments like high enthalpy plasma flows, fusion plasma and rocket motor combustion chambers based on solving the inverse heat conduction problem in a semi-infinite environment. This approach strongly depends on model parameters and geometrical aspects of the sensor design. In this work the surface heat flux is determined by solving the inverse heat conduction problem using an identified system as a direct model. The identification of the system is performed using calibration measurements with modern laser technique and advanced data handling. The results of the identified thermo-physical system show that a non-integer model appears most adapted to this particular problem. It is concluded that the new method improves the heat flux sensor significantly and furthermore extend its application to very short measurement times.

  17. Thomson scattering measurements from asymmetric interpenetrating plasma flows

    SciTech Connect

    Ross, J. S. Moody, J. D.; Fiuza, F.; Ryutov, D.; Divol, L.; Huntington, C. M.; Park, H.-S.

    2014-11-15

    Imaging Thomson scattering measurements of collective ion-acoustic fluctuations have been utilized to determine ion temperature and density from laser produced counter-streaming asymmetric flows. Two foils are heated with 8 laser beams each, 500 J per beam, at the Omega Laser facility. Measurements are made 4 mm from the foil surface using a 60 J 2ω probe laser with a 200 ps pulse length. Measuring the electron density and temperature from the electron-plasma fluctuations constrains the fit of the multi-ion species, asymmetric flows theoretical form factor for the ion feature such that the ion temperatures, ion densities, and flow velocities for each plasma flow are determined.

  18. Low Temperature Metal Free Growth of Graphene on Insulating Substrates by Plasma Assisted Chemical Vapor Deposition.

    PubMed

    Muñoz, R; Munuera, C; Martínez, J I; Azpeitia, J; Gómez-Aleixandre, C; García-Hernández, M

    2017-03-01

    Direct growth of graphene films on dielectric substrates (quartz and silica) is reported, by means of remote electron cyclotron resonance plasma assisted chemical vapor deposition r-(ECR-CVD) at low temperature (650°C). Using a two step deposition process- nucleation and growth- by changing the partial pressure of the gas precursors at constant temperature, mostly monolayer continuous films, with grain sizes up to 500 nm are grown, exhibiting transmittance larger than 92% and sheet resistance as low as 900 Ω·sq(-1). The grain size and nucleation density of the resulting graphene sheets can be controlled varying the deposition time and pressure. In additon, first-principles DFT-based calculations have been carried out in order to rationalize the oxygen reduction in the quartz surface experimentally observed. This method is easily scalable and avoids damaging and expensive transfer steps of graphene films, improving compatibility with current fabrication technologies.

  19. Cyan laser diode grown by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Turski, H. Muziol, G.; Wolny, P.; Cywiński, G.

    2014-01-13

    We demonstrate AlGaN-cladding-free laser diodes (LDs), operating in continuous wave (CW) mode at 482 nm grown by plasma-assisted molecular beam epitaxy (PAMBE). The maximum CW output power was 230 mW. LDs were grown on c-plane GaN substrates obtained by hydride vapor phase epitaxy. The PAMBE process was carried out in metal-rich conditions, supplying high nitrogen flux (Φ{sub N}) during quantum wells (QWs) growth. We found that high Φ{sub N} improves quality of high In content InGaN QWs. The role of nitrogen in the growth of InGaN on (0001) GaN surface as well as the influence of LDs design on threshold current density are discussed.

  20. Low temperature metal free growth of graphene on insulating substrates by plasma assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Muñoz, R.; Munuera, C.; Martínez, J. I.; Azpeitia, J.; Gómez-Aleixandre, C.; García-Hernández, M.

    2017-03-01

    Direct growth of graphene films on dielectric substrates (quartz and silica) is reported, by means of remote electron cyclotron resonance plasma assisted chemical vapor deposition r-(ECR-CVD) at low temperature (650 °C). Using a two step deposition process- nucleation and growth- by changing the partial pressure of the gas precursors at constant temperature, mostly monolayer continuous films, with grain sizes up to 500 nm are grown, exhibiting transmittance larger than 92% and sheet resistance as low as 900 Ω sq-1. The grain size and nucleation density of the resulting graphene sheets can be controlled varying the deposition time and pressure. In additon, first-principles DFT-based calculations have been carried out in order to rationalize the oxygen reduction in the quartz surface experimentally observed. This method is easily scalable and avoids damaging and expensive transfer steps of graphene films, improving compatibility with current fabrication technologies.

  1. Photoluminescence studies of ZnO nanorods grown by plasma-assisted molecular beam epitaxy.

    PubMed

    Kim, Min Su; Nam, Giwoong; Leem, Jae-Young

    2013-05-01

    Metal catalyst-free ZnO nanorods were grown on PS with buffer layers grown at 450 degrees C by plasma-assisted molecular beam epitaxy. Room temperature and temperature-dependent photoluminescence were carried out to investigate the optical properties of the ZnO nanorods with the average diameter of 120 nm and length of 300 nm. Three emission peaks, free excition, neutral-donor exciton, and free electron-to-neutral acceptor, were observed at 10 K. Huang-Rhys factor S of the ZnO nanorods was 0.978, which is much higher than that of ZnO thin films. The values of Varshni's empirical equation fitting parameters were alpha = 4 x 10(-3) eV/K, beta = 4.1 x 10(4) K, and E9(0) = 3.388 eV and the activation energy was about 96 meV.

  2. Low Temperature Metal Free Growth of Graphene on Insulating Substrates by Plasma Assisted Chemical Vapor Deposition

    PubMed Central

    Muñoz, R.; Munuera, C.; Martínez, J. I.; Azpeitia, J.; Gómez-Aleixandre, C.; García-Hernández, M.

    2016-01-01

    Direct growth of graphene films on dielectric substrates (quartz and silica) is reported, by means of remote electron cyclotron resonance plasma assisted chemical vapor deposition r-(ECR-CVD) at low temperature (650°C). Using a two step deposition process- nucleation and growth- by changing the partial pressure of the gas precursors at constant temperature, mostly monolayer continuous films, with grain sizes up to 500 nm are grown, exhibiting transmittance larger than 92% and sheet resistance as low as 900 Ω·sq-1. The grain size and nucleation density of the resulting graphene sheets can be controlled varying the deposition time and pressure. In additon, first-principles DFT-based calculations have been carried out in order to rationalize the oxygen reduction in the quartz surface experimentally observed. This method is easily scalable and avoids damaging and expensive transfer steps of graphene films, improving compatibility with current fabrication technologies. PMID:28070341

  3. Pioneer 9 plasma wave and solar plasma measurements for the August 1972 storm period

    NASA Technical Reports Server (NTRS)

    Scarf, F. L.; Wolfe, J. H.

    1974-01-01

    The solar disturbances of August 1972 produced large-scale solar wind perturbations that were detected by the Pioneer 9 plasma probe, electric field detector, and magnetometer for an extended time period commencing early on August 3. During this ten-day interval the interplanetary plasma parameters at r approximately equal 0.8 AU varied over unusually wide ranges, so that the conditions for generation of high and low VLF wave levels could be identified fairly readily. It is demonstrated that no measurable signals were detected in the broadband electric field channel (sensitive to waves with f greater than or equal to 100 Hz in the spacecraft frame of reference) unless the proton density was high enough to yield a proton plasma frequency with f greater than or about equal to 100 Hz. The analysis suggests that waves related to ion acoustic oscillations were detected throughout the extended storm period.

  4. Pioneer 9 plasma wave and solar plasma measurements for the August 1972 storm period

    NASA Technical Reports Server (NTRS)

    Scarf, F. L.; Wolfe, J. H.

    1974-01-01

    The solar disturbances of August 1972 produced large-scale solar wind perturbations that were detected by the Pioneer 9 plasma probe, electric field detector, and magnetometer for an extended time period commencing early on August 3. During this ten-day interval the interplanetary plasma parameters at r approximately equal 0.8 AU varied over unusually wide ranges, so that the conditions for generation of high and low VLF wave levels could be identified fairly readily. It is demonstrated that no measurable signals were detected in the broadband electric field channel (sensitive to waves with f greater than or equal to 100 Hz in the spacecraft frame of reference) unless the proton density was high enough to yield a proton plasma frequency with f greater than or about equal to 100 Hz. The analysis suggests that waves related to ion acoustic oscillations were detected throughout the extended storm period.

  5. Lunar plasma measurement by MAP-PACE onboard KAGUYA (SELENE)

    NASA Astrophysics Data System (ADS)

    Saito, Yoshifumi

    Low energy charged particles around the Moon were vigorously observed by Moon orbiting satellites and plasma instrumentation placed on the lunar surface in 1960s and 1970s. Though there were some satellites that explored the Moon afterwards, most of them were dedicated to the global mapping of the lunar surface. KAGUYA(SELENE) is a Japanese lunar orbiter that studies the origin and evolution of the Moon by means of global mapping of element abundances, mineralogical composition, and surface geographical mapping from 100km altitude. KAGUYA was successfully launched on 14 September 2007 by HIIA launch vehicle from Tanegashima Space Center in Japan. KAGUYA was inserted into a circular lunar polar orbit of 100km altitude and started continuous observation in mid-December 2007. One of the fourteen science instruments MAP-PACE (MAgnetic field and Plasma experiment - Plasma energy Angle and Composition Experiment) was developed for the comprehensive three-dimensional plasma measurement around the Moon. MAP-PACE consists of 4 sensors: ESA (Electron Spectrum Analyzer)-S1, ESA-S2, IMA (Ion Mass Analyzer), and IEA (Ion Energy Analyzer). ESA-S1 and S2 measure the distribution function of low energy electrons below 15keV. IMA and IEA measure the distribution function of low energy ions below 28keV/q. IMA has an ability to discriminate the ion mass with high mass resolution. PACE sensors have been measuring solar wind, plasmas in the wake region of the Moon and plasmas in the Earth's magnetosphere. ESA sensors have discovered electron heating over magnetic anomalies on the lunar surface. ESA sensors have also observed electrons accelerated from the lunar surface in the wake region. PACE ion sensors have discovered new features of low energy ions around the Moon. IMA has discovered the existence of alkali ions that are originated from the lunar surface or lunar atmosphere and are picked up by the solar wind. IEA and IMA sensors discovered solar wind reflection by the Moon. PACE

  6. Experiments and models of the plasma assisted chemical vapor deposition of copper from copper hexafluoroacetylacetonate and hydrogen

    NASA Astrophysics Data System (ADS)

    Lakshmanan, Satish Kumar

    Low resistivity, high electromigration and stress migration resistance of copper interconnects will improve device reliability and lower RC delays, as device dimensions decrease into the deep sub-micron region. Plasma assisted chemical vapor deposition (PACVD) using a Hsb2 plasma and copper(II) hexafluoro acetylacetonate (Cu(Hfa)sb2), is an attractive process because of its ability to form pure copper films conformally, in narrow vias and trenches, at low substrate temperatures (150-220sp°C). Copper films have been deposited by hydrogen plasma assisted chemical vapor deposition at pressures of 0.5-3.0 torr, substrate temperatures of 150-250sp°C, plasma powers of 3.0-85.0 W and precursor mole fractions of 0.1-0.8%, in a cold wall PACVD research reactor and a commercial Watkins Johnson Select 7000 reactor. Film purity and morphology have been analyzed by X-Ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-Ray diffraction (XRD). Under the conditions investigated, the film growth rates were measured to be in the range of 40-200 A/min. An activation energy of 5 kcal/mol is suggested for the deposition, by the experiments. Further, the deposition rate, precursor conversion, film purity and morphology can be tailored by adjusting the operating conditions appropriately. A new distributed parameter model of a capacitively coupled rf Hsb2 discharge including a copper precursor has been developed, from the first three moments of the Boltzmann equation. The model predicts the concentrations and fluxes of (1) the positive ions Hsp+, Hsbsp{2}{+} and Hsbsp{3}{+} (2) the electrons and (3) atomic hydrogen, under the conditions that produce low resistivity copper films. A lumped parameter model has also been developed, which shows that Cu(Hfa)sb2 decomposes only when electron concentrations are high, resulting in the incorporation of carbon and fluorine in the growing film. However, at low pressures and powers, Cu(Hfa)sb2 reacts predominantly with H on

  7. Coupling of an exploding plasma to a magnetized ambient plasma measured with LIF

    NASA Astrophysics Data System (ADS)

    Bonde, Jeffrey; Vincena, Stephen; Gekelman, Walter

    2013-10-01

    The coupling of plasma jets to ambient media near young stellar objects, Herbig-Haro objects, and supernova remnants is of considerable interest to the astrophysical community. In this work, we study the interaction of a laboratory scale jet formed by a carbon laser-produced plasma (LPP) with the ions of a magnetized argon background plasma (njet /nAr < 30 ,vjet/cs = 20 ,vjet/vA <=1) using laser-induced fluorescence (LIF). The excitation light was provided by a planar beam of a pulsed dye laser which, by tuning to the Doppler-broadened 611.5 nm absorption line, sampled the distribution function of metastable Ar-II separating the background from the components of the jet. A fast shutter (>= 3 ns) CCD camera captured the 461 nm fluorescence with 40 ns time and .6 mm2 spatial resolutions. The distribution functions obtained from the LIF diagnostic reveal significant density enhancement and a subsonic parallel drift localized at the LPP-ambient interface. Within the jet region, the background ion signal indicates the formation of a density void and suggests a lateral snow-plow effect. To our knowledge, this is the first LIF measurement of a supersonic jet coupling to an ambient plasma. Supplemental Langmuir probe measurements characterize the jet's dimensions and dependence on magnetic field strength and background ion mass up to 6 meters from the LPP source. This experiment was conducted in the Large Plasma Device at the Basic Plasma Science Facility and funded by grants from the US Department of Energy and the National Science Foundation.

  8. The Importance of Optical Pathlength Control for Plasma Absorption Measurements

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, Surendra P.; Meyyappan, M.; Partridge, Harry (Technical Monitor)

    2001-01-01

    An inductively coupled GEC Cell with modified viewing ports has been used to measure in-situ absorption in CF4 plasmas via Fourier Transform Infrared Spectroscopy, and the results compared to those obtained in a standard viewport configuration. The viewing ports were modified so that the window boundary is inside, rather than outside, of the GEC cell. Because the absorption obtained is a spatially integrated absorption, measurements made represent an averaging of absorbing species inside and outside of the plasma. This modification is made to reduce this spatial averaging and thus allow a more accurate estimation of neutral species concentrations and temperatures within the plasmas. By reducing this pathlength, we find that the apparent CF4 consumption increases from 65% to 95% and the apparent vibrational temperature of CF4 rises by 50-75 K. The apparent fraction of etch product SiF4 decreases from 4% to 2%. The data suggests that these density changes may be due to significant temperature gradients between the plasma and chamber viewports.

  9. Electric Field Double Probe Measurements for Ionospheric Space Plasma Experiments

    NASA Technical Reports Server (NTRS)

    Pfaff, R.

    1999-01-01

    Double probes represent a well-proven technique for gathering high quality DC and AC electric field measurements in a variety of space plasma regimes including the magnetosphere, ionosphere, and mesosphere. Such experiments have been successfully flown on a variety of spacecraft including sounding rockets and satellites. Typical instrument designs involve a series of trades, depending on the science objectives, type of platform (e.g., spinning or 3-axis stabilized), expected plasma regime where the measurements will be made, available telemetry, budget, etc. In general, ionospheric DC electric field instruments that achieve accuracies of 0.1 mV/m or better, place spherical sensors at large distances (10m or more) from the spacecraft body in order to extend well beyond the spacecraft wake and sheath and to achieve large signal-to-noise ratios for DC and long wavelength measurements. Additional sets of sensors inboard of the primary, outermost sensors provide useful additional information, both for diagnostics of the plasma contact potentials, which particularly enhance the DC electric field measurements on non-spinning spacecraft, and for wavelength and phase velocity measurements that use the spaced receiver or "interferometer" technique. Accurate attitude knowledge enables B times V contributions to be subtracted from the measured potentials, and permits the measured components to be rotated into meaningful geophysical reference frames. We review the measurement technique for both DC and wave electric field measurements in the ionosphere discussing recent advances involving high resolution burst memories, multiple baseline double probes, new sensor surface materials, biasing techniques, and other considerations.

  10. Plasma-assisted physical vapor deposition surface treatments for tribological control

    NASA Technical Reports Server (NTRS)

    Spalvins, Talivaldis

    1990-01-01

    In any mechanical or engineering system where contacting surfaces are in relative motion, adhesion, wear, and friction affect reliability and performance. With the advancement of space age transportation systems, the tribological requirements have dramatically increased. This is due to the optimized design, precision tolerance requirements, and high reliability expected for solid lubricating films in order to withstand hostile operating conditions (vacuum, high-low temperatures, high loads, and space radiation). For these problem areas the ion-assisted deposition/modification processes (plasma-based and ion beam techniques) offer the greatest potential for the synthesis of thin films and the tailoring of adherence and chemical and structural properties for optimized tribological performance. The present practices and new approaches of applying soft solid lubricant and hard wear resistant films to engineering substrates are reviewed. The ion bombardment treatments have increased film adherence, lowered friction coefficients, and enhanced wear life of the solid lubricating films such as the dichalcogenides (MoS2) and the soft metals (Au, Ag, Pb). Currently, sputtering is the preferred method of applying MoS2 films; and ion plating, the soft metallic films. Ultralow friction coefficients (less than 0.01) were achieved with sputtered MoS2. Further, new diamond-like carbon and BN lubricating films are being developed by using the ion assisted deposition techniques.

  11. A convenient method to measure blood-plasma concentration ratio using routine plasma collection in in vivo pharmacokinetic studies.

    PubMed

    Berezhkovskiy, Leonid M; Zhang, Xiaolin; Cheong, Jonathan

    2011-12-01

    A practical time-saving method of determination of equilibrium blood-plasma concentration ratio is described. The method is based on the analysis of compound plasma concentrations in regular blood sample and the blood sample diluted with blank plasma. Since only plasma concentrations are analyzed, the method can be conveniently applied in routine pharmacokinetic studies with minimal additional work for obtaining blood-plasma ratio. The method can also be easily used in in vitro experiment. The results obtained by suggested method are in good agreement with that obtained by common in vitro measurements of blood-plasma ratio.

  12. Remote plasma assisted growth of graphene films: structure and physical properties

    NASA Astrophysics Data System (ADS)

    Rouvimov, Sergei; Nandamuri, Gopichand; Solanki, Raj

    2010-03-01

    The unique electrical properties of graphene, in particular ballistic transport and tunable transport properties have opened up exciting possibilities for this material as a replacement for silicon [1-2]. While graphene is commonly produced in research laboratories by mechanical exfoliation of highly oriented pyrolytic graphite, mass production of graphene-based devices requires technological approach to synthesize thin graphene films such as chemical vapor deposition. In present work, single and multiple layers of graphene films were grown on (111) oriented single crystals of nickel and polycrystalline nickel films using remote plasma assisted chemical vapor deposition. Remote plasma was employed to eliminate the effect of the electrical field on the orientation of the grown graphene films, as well as reduce the growth temperature compared to conventional chemical vapor deposition. The electrical and optical properties, including high resolution transmission electron microscopy of these films, suggest that this approach is both versatile and scalable for potential large area optoelectronic applications. [4pt] [1] T. Ohta, et al. Science 2006, 313, 951- 954 [0pt] [2] Y. B, Zhang, et al. Nature 2005, 438, 201- 204

  13. Low-temperature plasma-assisted growth of optically transparent, highly oriented nanocrystalline AlN

    NASA Astrophysics Data System (ADS)

    Mirpuri, C.; Xu, S.; Long, J. D.; Ostrikov, K.

    2007-01-01

    Optically transparent, highly oriented nanocrystalline AlN(002) films have been synthesized using a hybrid plasma enhanced chemical vapor deposition and plasma-assisted radio frequency (rf) magnetron sputtering process in reactive Ar+N2 and Ar+N2+H2 gas mixtures at a low Si(111)/glass substrate temperature of 350 °C. The process conditions, such as the sputtering pressure, rf power, substrate temperature, and N2 concentration were optimized to achieve the desired structural, compositional, and optical characteristics. X-ray diffractometry reveals the formation of highly c-oriented AlN films at a sputtering pressure of 0.8 Pa. Field emission scanning electron microscopy suggests the uniform distribution of AlN grains over large surface areas and also the existence of highly oriented in the (002) direction columnar structures of a typical length ˜100-500 nm with an aspect ratio of ˜7-15. X-ray photoelectron and energy dispersive x-ray spectroscopy suggest that films deposited at a rf power of 400 W feature a chemically pure and near stoichiometric AlN. The bonding states of the AlN films have been confirmed by Raman and Fourier transform infrared spectroscopy showing strong E2 (high) and E1 transverse optical phonon modes. Hydrogenated AlN films feature an excellent optical transmittance of ˜80% in the visible region of the spectrum, promising for advanced optical applications.

  14. Plasma-assisted combustion technology for NOx reduction in industrial burners.

    PubMed

    Lee, Dae Hoon; Kim, Kwan-Tae; Kang, Hee Seok; Song, Young-Hoon; Park, Jae Eon

    2013-10-01

    Stronger regulations on nitrogen oxide (NOx) production have recently promoted the creation of a diverse array of technologies for NOx reduction, particularly within the combustion process, where reduction is least expensive. In this paper, we discuss a new combustion technology that can reduce NOx emissions within industrial burners to single-digit parts per million levels without employing exhaust gas recirculation or other NOx reduction mechanisms. This new technology uses a simple modification of commercial burners, such that they are able to perform plasma-assisted staged combustion without altering the outer configuration of the commercial reference burner. We embedded the first-stage combustor within the head of the commercial reference burner, where it operated as a reformer that could host a partial oxidation process, producing hydrogen-rich reformate or synthesis gas product. The resulting hydrogen-rich flow then ignited and stabilized the combustion flame apart from the burner rim. Ultimately, the enhanced mixing and removal of hot spots with a widened flame area acted as the main mechanisms of NOx reduction. Because this plasma burner acted as a low NOx burner and was able to reduce NOx by more than half compared to the commercial reference burner, this methodology offers important cost-effective possibilities for NOx reduction in industrial applications.

  15. Plasma assisted deposition of single and multistacked TiO2 hierarchical nanotube photoanodes.

    PubMed

    Nicolas Filippin, A; Sanchez-Valencia, Juan R; Idígoras, Jesús; Rojas, T Cristina; Barranco, Angel; Anta, Juan A; Borras, Ana

    2017-04-13

    We present herein an evolved methodology for the growth of nanocrystalline hierarchical nanotubes combining physical vapor deposition of organic nanowires (ONWs) and plasma enhanced chemical vacuum deposition of anatase TiO2 layers. The ONWs act as vacuum removable 1D and 3D templates, with the whole process occurring at temperatures ranging from RT to 250 °C. As a result, a high density of hierarchical nanotubes with tunable diameter, length and tailored wall microstructures are formed on a variety of processable substrates as metal and metal oxide films or nanoparticles including transparent conductive oxides. The reiteration of the process leads to the development of an unprecedented 3D nanoarchitecture formed by stacking the layers of hierarchical TiO2 nanotubes. As a proof of concept, we present the superior performance of the 3D nanoarchitecture as a photoanode within an excitonic solar cell with efficiencies as high as 4.69% for a nominal thickness of the anatase layer below 2.75 μm. Mechanical stability and straightforward implementation in devices are demonstrated at the same time. The process is extendable to other functional oxides fabricated by plasma-assisted methods with readily available applications in energy harvesting and storage, catalysis and nanosensing.

  16. Plasma assisted ignition with nanosecond surface dielectric barrier discharge. Two modes of nanosecond surface discharge

    NASA Astrophysics Data System (ADS)

    Shcherbanev, Sergey; Popov, Nikolay; Starikovskaia, Svetlana; LPP Team; LIA France-Russia Collaboration

    2016-09-01

    Nanosecond surface dielectric barrier discharge (nSDBD) is an efficient tool for a multi-point plasma-assisted ignition of combustible mixtures at elevated pressures. In combustible mixtures, nSDBD initiates numerous combustion waves propagating from the electrode. This work presents a comparative experimental study of the surface dielectric barrier discharge initiated by high voltage pulses (U =+/-(20-60) kV) of different polarities in air at elevated pressures (P =1 -12 bar). Discharge morphology, deposited energy, and spectroscopy of the discharges are analyzed. Differences between the discharges of the different polarity, as well as the changes in the discharge morphology with changing of a gas mixture composition, are discussed. The initiation of combustion with nSDBD was studied experimentally at high initial pressures up to 6 bar on the example of lean H2/Air. The ignition is initiated with two different discharge modes: streamer and filamentary. The influence of the discharge structure and energy deposition on the ignition is demonstrated. Three regimes of multi-point ignition were observed: ignition with a few kernels, quasi-uniform ignition along the edge of high voltage electrodes and ignition along the plasma channels.

  17. Air plasma assisting microcontact deprinting and printing for gold thin film and PDMS patterns.

    PubMed

    Gou, Hong-Lei; Xu, Jing-Juan; Xia, Xing-Hua; Chen, Hong-Yuan

    2010-05-01

    In this paper, we present a simple method to fabricate gold film patterns and PDMS patterns by air plasma assisting microcontact deprinting and printing transfer approaches. Chemical gold plating is employed instead of conventional metal evaporation or sputtering to obtain perfect gold film both on flat and topographic PDMS chips, and complicated SAM precoating is replaced by simple air plasma treatment to activate both the surface of gold film and PDMS. In this way, large area patterns of conductive gold film and PDMS patterns could be easily obtained on the elastomeric PDMS substrate. Both the chemical plating gold film and transferred gold film were of good electrochemical properties and similar hydrophilicity with smooth and conductive surface, which made it potentially useful in microfluidic devices and electronics. The gold transfer mechanism is discussed in detail. For typical applications, a cell patterning chip based on the gold pattern was developed to imply the interfacial property, and dielectrophoresis control of live cells was carried out with the patterned gold as interdigital electrodes to show the conductivity.

  18. Field-assisted paper spray mass spectrometry for the quantitative evaluation of imatinib levels in plasma.

    PubMed

    D'Aronco, Sara; Calandra, Eleonora; Crotti, Sara; Toffoli, Giuseppe; Marangon, Elena; Posocco, Bianca; Traldi, Pietro; Agostini, Marco

    Drug levels in patients' bloodstreams vary among individuals and consequently therapeutic drug monitoring (TDM) is fundamental to controlling the effective therapeutic range. For TDM purposes, different analytical approaches have been used, mainly based on immunoassay, liquid chromatography- ultraviolet, liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. More recently a matrix-assisted laser desorption/ionisation method has been proposed for the determination of irinotecan levels in the plasma of subjects under therapy and this method has been cross- validated by comparison with data achieved by LC-MS/MS. However, to reach an effective point-of-care monitoring of plasma drug concentrations, a TDM platform technology for fast, accurate, low-cost assays is required. In this frame, recently the use of paper spray mass spectrometry, which is becoming a popular and widely employed MS method, has been proposed. In this paper we report the results obtained by the development of a paper spray-based method for quantitative analysis in plasma samples of imatinib, a new generation of anticancer drug. Preliminary experiments showed that poor sensitivity, reproducibility and linear response were obtained by the "classical" paper spray set-up. In order to achieve better results, it was thought of interest to operate in presence of a higher and more homogeneous electrical field. For this aim, a stainless steel needle connected with the high voltage power supply was mounted below the paper triangle. Furthermore, in order to obtain valid quantitative data, we analysed the role of the different equilibria participating to the phenomena occurring in paper spray experiments, depending either on instrumental parameters or on the chemical nature of analyte and solvents. A calibration curve was obtained by spiking plasma samples containing different amounts of imatinib (1) with known amounts of deuterated imatinib (1d3) as

  19. Galileo measurements of plasma density in the Io torus

    NASA Astrophysics Data System (ADS)

    Bagenal, F.; Crary, F. J.; Stewart, A. I. F.; Schneider, N. M.; Gurnett, D. A.; Kurth, W. S.; Frank, L. A.; Paterson, W. R.

    1997-09-01

    The measurements of electron density made by the Plasma Wave Subsystem instruments on Galileo during its pass through the torus on December 7th, 1995 are compared with a model based on Voyager 1 measurements made in March 1979. Outside Io's orbit, the plasma densities observed by Galileo are approximately a factor of two higher than the Voyager values. Shortly after crossing Io's orbit, the Galileo density profile dropped sharply and remained at low values for the rest of the inbound leg, suggesting that the 'ribbon' region was either absent or much farther from Jupiter than usual. The peak density on the outbound leg is consistent with Voyager-based predictions for the cold torus in both location (5.1 RJ) and magnitude (950 cm-3). Inside 5 RJ the density dropped sharply to less than 3 cm-3.

  20. Mass spectrometer for measurements of relative ion concentrations in plasmas

    NASA Technical Reports Server (NTRS)

    Suszcynsky, David M.; D'Angelo, Nicola; Merlino, Robert L.

    1988-01-01

    A mass spectrometer which can be used to measure relative ion concentrations in a multiion component plasma has been designed for use in a strong (1-4-kG) uniform magnetic field. The spectrometer features an acceleration region which accelerates thermal ions through a series of three tantalum electrodes at a 30 deg angle to the B field, and a collection region in which ions are selectively collected, depending on the size of their gyroradii, by a cylindrical collector. Relative ion concentrations are determined from measurements of the collector current as a function of accelerating voltage. Results obtained using this instrument in a Q-machine device operated with a two-ion (Cs+/K+) component plasma are presented.

  1. Measurements of Plasma Potential Distribution in Segmented Electrode Hall Thruster

    SciTech Connect

    Y. Raitses; D. Staack; N.J. Fisch

    2001-10-16

    Use of a segmented electrode placed at the Hall thruster exit can substantially reduce the voltage potential drop in the fringing magnetic field outside the thruster channel. In this paper, we investigate the dependence of this effect on thruster operating conditions and segmented electrode configuration. A fast movable emissive probe is used to measure plasma potential in a 1 kW laboratory Hall thruster with semented electrodes made of a graphite material. Relatively small probe-induced perturbations of the thruster discharge in the vicinity of the thruster exit allow a reasonable comparison of the measured results for different thruster configurations. It is shown that the plasma potential distribution is almost not sensitive to changes of the electrode potential, but depends on the magnetic field distribution and the electrode placement.

  2. Use of plasma "reconstitution" during cardio pulmonary bypass for a heart transplant after previous left ventricular assist device implant surgery.

    PubMed

    Babaev, A; Saczkowski, R; Hynes, M; Boodhwani, M; Hudson, C C C

    2014-01-01

    The case report describes a novel technique of pre-emptive plasma "reconstitution" prior to disengagement from cardiopulmonary bypass (CPB) to minimize RV volume overload. The concomitant use of hemoconcentration facilitates volume and blood product management in cardiac transplant after previous left ventricular assist device implant surgery.

  3. 10 CFR 455.110 - Grant application submittals for technical assistance and energy conservation measures.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... assistance for energy conservation measures, including renewable resource measures, shall include the... 10 Energy 3 2013-01-01 2013-01-01 false Grant application submittals for technical assistance and energy conservation measures. 455.110 Section 455.110 Energy DEPARTMENT OF ENERGY ENERGY...

  4. 10 CFR 455.110 - Grant application submittals for technical assistance and energy conservation measures.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... assistance for energy conservation measures, including renewable resource measures, shall include the... 10 Energy 3 2011-01-01 2011-01-01 false Grant application submittals for technical assistance and energy conservation measures. 455.110 Section 455.110 Energy DEPARTMENT OF ENERGY ENERGY...

  5. 10 CFR 455.110 - Grant application submittals for technical assistance and energy conservation measures.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... assistance for energy conservation measures, including renewable resource measures, shall include the... 10 Energy 3 2012-01-01 2012-01-01 false Grant application submittals for technical assistance and energy conservation measures. 455.110 Section 455.110 Energy DEPARTMENT OF ENERGY ENERGY...

  6. Kinetic Effects of Non-Equilibrium Plasma-Assisted Methane Oxidation on Diffusion Flame Extinction Limits

    DTIC Science & Technology

    2011-01-01

    measured using the Two-photon Absorption Laser-Induced Fluorescence (TALIF) method (for atomic oxygen, O), Fourier Transform Infrared ( FTIR ) spectroscopy...photon Absorption Laser-Induced Fluorescence (TALIF) method (for atomic oxygen, O), Fourier Transform Infrared ( FTIR ) spectroscopy and Gas...and ozone (O3) from other plasma related species and shown that both (at concentrations of several thousand ppm) can enhance flame speeds by a few

  7. Measurement of the Decelerating Wake in a Plasma Wakefield Accelerator

    SciTech Connect

    Blumenfeld, I.; Decker, F. J.; Hogan, M. J.; Ischebeck, R.; Iverson, R. H.; Kirby, N.; Siemann, R. H.; Walz, D. R.; Clayton, C. E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W. B.; Zhou, M.; Katsouleas, T.; Muggli, P.; Oz, E.

    2009-01-22

    Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch lengths were varied systematically at constant charge. The effort to extract a measurement of the decelerating wake from the maximum energy loss of the electron beam is discussed.

  8. Optimization of Light Measurements for a Low Energy Plasma

    DTIC Science & Technology

    2005-06-01

    investigate the behavior of the phenomenon of surface flashover and develop techniques to control its behavior. As part of this research, studies...discussed in the hopes of obtaining an understanding of all aspects of the plasma resulting from surface flashover technologies. II...initiation. Infrared photodiodes offer sufficiently fast response times (1 ns) to measure the pulse waveforms of this class of surface flashover

  9. Quasi-monochromatic measurements of homogeneous arc plasmas.

    NASA Technical Reports Server (NTRS)

    Klein, L.

    1973-01-01

    The refined diagnostic information obtainable by high-order spectrometry is illustrated by the results of quantitative measurements of a few rotational lines of OH in the ultraviolet spectrum of water-vapor plasmas generated in a wall-stabilized arc. Because of the high spectral and spatial resolution achieved in end-on measurements, the emission and also the absorption coefficients pertaining to homogeneous arc regions were obtained directly from measured line spectra - although the absorption was not measured explicitly - leading to the occupation of the upper and the lower state for the transition. The gas temperature was determined from the halfwidth of the Doppler-broadened rotational lines. The measured resolving power of the spectrometer was of the order of 400,000 in these measurements.

  10. Plasma Impedance Spectrum Analyzer (PISA): an advanced impedance probe for measuring plasma density and other parameters

    NASA Astrophysics Data System (ADS)

    Rowland, D. E.; Pfaff, R. F.; Uribe, P.; Burchill, J.

    2006-12-01

    High-accuracy, high-cadence measurements of ionospheric electron density between 100 and a few x 106 / cc and electron temperature from 200 K to a few thousand K are of critical importance for understanding conductivity, Joule heating rates, and instability growth rates. We present results from the development of an impedance probe at NASA GSFC and show its strengths relative to other measurement techniques. Complementary measurement techniques such as Langmuir Probes, while providing extremely high measurement cadence, suffer from uncertainties in calibration, surface contamination effects, and wake/sheath effects. Impedance Probes function by measuring the phase shift between the voltage on a long antenna and the current flowing from the antenna into the plasma as a function of frequency. At frequencies for which the phase shift is zero, a plasma resonance is assumed to exist. These resonances depend on a variety of plasma parameters, including the electron density, electron temperature, and magnetic field strength, as well as the antenna geometry, angle between the antenna and the magnetic field, and sheath / Debye length effects, but do not depend on the surface properties of the antenna. Previous impedance probe designs which "lock" onto the upper hybrid resonance are susceptible to losing lock in low-density environments. Information about other resonances, including the series resonance (which strongly depends on temperature) and other resonances which may occur near the upper hybrid, confounding its identification, are typically not transmitted. The novel features of the GSFC Impedance Probe (PISA) include: 1) A white noise generator that stimulates a wide range of frequencies simultaneously, allowing the instrument to send down the entire impedance frequency spectrum every few milliseconds. This allows identification of all resonance frequencies, including the series resonance which depends on temperature. 2) DC bias voltage stepping to bring the antenna

  11. Characterizing Suspension Plasma Spray Coating Formation Dynamics through Curvature Measurements

    NASA Astrophysics Data System (ADS)

    Chidambaram Seshadri, Ramachandran; Dwivedi, Gopal; Viswanathan, Vaishak; Sampath, Sanjay

    2016-12-01

    Suspension plasma spraying (SPS) enables the production of variety of microstructures with unique mechanical and thermal properties. In SPS, a liquid carrier (ethanol/water) is used to transport the sub-micrometric feedstock into the plasma jet. Considering complex deposition dynamics of SPS technique, there is a need to better understand the relationships among spray conditions, ensuing particle behavior, deposition stress evolution and resultant properties. In this study, submicron yttria-stabilized zirconia particles suspended in ethanol were sprayed using a cascaded arc plasma torch. The stresses generated during the deposition of the layers (termed evolving stress) were monitored via the change in curvature of the substrate measured using an in situ measurement apparatus. Depending on the deposition conditions, coating microstructures ranged from feathery porous to dense/cracked deposits. The evolving stresses and modulus were correlated with the observed microstructures and visualized via process maps. Post-deposition bi-layer curvature measurement via low temperature thermal cycling was carried out to quantify the thermo-elastic response of different coatings. Lastly, preliminary data on furnace cycle durability of different coating microstructures were evaluated. This integrated study involving in situ diagnostics and ex situ characterization along with process maps provides a framework to describe coating formation mechanisms, process parametrics and microstructure description.

  12. Viscous Transport Measurements in Pure-Electron Plasmas.

    NASA Astrophysics Data System (ADS)

    Driscoll, C. F.; Kriesel, J. M.

    2000-10-01

    Measurements of the kinematic viscosity κ in a quiescent pure-electron plasma are up to 10^8 × larger than predicted by Boltzmann collisional theory. This viscosity acts on radial shears in the total (E × B and diamagnetic) azimuthal rotation velocity v_θ, resulting in radially inward or outward particle fluxes Γ_r. Experimental values of κ are obtained from the measured density n(r,t) and temperature T(r,t), which give both v_θ (r,t) and Γr (r,t). The viscosity is due to long range ``E × B drift collisions'' with impact parameters rc < ρ < λ_D, whereas Boltzmann transport theory describes only velocity-scattering collisions with ρ < r_c. The measured viscosity scales as κ ∝ B^1 L_p-1, suggesting that multiple correlated long-range collisions are important. The B^1 scaling is qualitatively similar to recent ``bounce-averaged'' or ``2D'' theories;(D.H.E. Dubin, Phys. Plasmas 5), 1688 (1998). but the surprising L_p-1 dependence on plasma length is as yet unexplained. Empirically, we find κ = νc λ_D^2 [1 + Nb ], where νc ≡ n barv b^2 and Nb is the number of axial bounces made by a thermal particle before shears separate it from a neighboring particle by a distance λ_D.

  13. Electron density dependence of impedance probe plasma potential measurements

    SciTech Connect

    Walker, D. N.; Blackwell, D. D.; Amatucci, W. E.

    2015-08-15

    In earlier works, we used spheres of various sizes as impedance probes in demonstrating a method of determining plasma potential, φ{sub p}, when the probe radius is much larger than the Debye length, λ{sub D}. The basis of the method in those works [Walker et al., Phys. Plasmas 13, 032108 (2006); ibid. 15, 123506 (2008); ibid. 17, 113503 (2010)] relies on applying a small amplitude signal of fixed frequency to a probe in a plasma and, through network analyzer-based measurements, determining the complex reflection coefficient, Γ, for varying probe bias, V{sub b}. The frequency range of the applied signal is restricted to avoid sheath resonant effects and ion contributions such that ω{sub pi} ≪ ω ≪ ω{sub pe}, where ω{sub pi} is the ion plasma frequency and ω{sub pe} is the electron plasma frequency. For a given frequency and applied bias, both Re(Z{sub ac}) and Im(Z{sub ac}) are available from Γ. When Re(Z{sub ac}) is plotted versus V{sub b}, a minimum predicted by theory occurs at φ{sub p} [Walker et al., Phys. Plasmas 17, 113503 (2010)]. In addition, Im(Z{sub ac}) appears at, or very near, a maximum at φ{sub p}. As n{sub e} decreases and the sheath expands, the minimum becomes harder to discern. The purpose of this work is to demonstrate that when using network analyzer-based measurements, Γ itself and Im(Z{sub ac}) and their derivatives are useful as accompanying indicators to Re(Z{sub ac}) in these difficult cases. We note the difficulties encountered by the most commonly used plasma diagnostic, the Langmuir probe. Spherical probe data is mainly used in this work, although we present limited data for a cylinder and a disk. To demonstrate the effect of lowered density as a function of probe geometry, we compare the cylinder and disk using only the indicator Re(Z{sub ac})

  14. Measuring Magnetic Fields in Photoionized Interstellar Plasmas (HII Regions)

    NASA Astrophysics Data System (ADS)

    Spangler, Steven; Costa, Allison

    2015-11-01

    Hot luminous stars photoionize the interstellar gas around them, creating plasmas with a very high ionization fraction. In astronomical terminology, these are called HII regions. They are dynamic plasmas, expanding due to overpressure with respect to the interstellar medium. We are making diagnostic measurements to determine the strength and structure of magnetic fields in these objects. This paper presents our results on the Rosette Nebula. We diagnose the magnetic field in the Rosette by measurements of Faraday rotation on lines of sight passing through the nebula. These measurements are made with the Very Large Array radio telescope of the National Radio Astronomy Observatory. We have measurements of the rotation measure for 18 lines of sight. Values of the mean, line of sight component of the magnetic field range from about 3 to 5 microGauss. We will discuss comparison of these measurements with models for modification of the interstellar magnetic field by an HII region. This work was supported by grants AST09-07911 and ATM09-56901 from the National Science Foundation.

  15. Online post-column solvent assisted and direct solvent-assisted electrospray ionization for chiral analysis of propranolol enantiomers in plasma samples.

    PubMed

    Elmongy, Hatem; Ahmed, Hytham; Wahbi, Abdel-Aziz; Koyi, Hirsh; Abdel-Rehim, Mohamed

    2015-10-30

    An Online post-column solvent-assisted ionization (OPSAI) method was developed for enhancing the ionization of the beta-blocker propranolol utilizing normal phase LC-MS/MS. Solvent-assisted electrospray ionization (SAESI) was studied by the introduction of the assistant solvents A: 0.5% Formic acid in Isopropanolol, B: 0.5% Formic acid in Isopropanolol-Water (1:1), and C: 0.5% Formic acid in water into the electrospray ionization chamber using a spray needle. Analyte molecules can be directly ionized by the aid of the assistant solvent spray. Both methods were applied to the chiral separation of propranolol enantiomers using normal phase analysis on cellulose-based chiral column. Interestingly, both methods are easy to handle and offer a wide range of assistant solvents that can be used in order to gain the optimum ionization of the analyte molecules. The both methods considerably improved the analyte signal and the peak area greatly increased. The propranolol average signal-to-noise (S/N) ratio was enhanced from 26±1 and 42±1 to 2341±61 and 1725±29 for R-propranolol and S-propranolol, respectively, when the post-column solvent method (OPSAI) was used with isopropanol-assistant solvent (A). While in case of solvent-assisted electrospray ionization method (SAESI) signal was enhanced from 26±1 and 42±1 to 2223±72 and 2155±58 for R-propranolol and S-propranolol, respectively, with water as an assistant solvent. The limit of detection was 10ng/mL and the method was linear in the range 50-2000ng/mL. The NPLC-MS method was applied for the determination of propranolol enantiomers in human plasma after microextraction by packed C18 sorbent.

  16. Alzheimer's disease: pathophysiological implications of measurement of plasma cortisol, plasma dehydroepiandrosterone sulfate, and lymphocytic corticosteroid receptors.

    PubMed

    Armanini, Decio; Vecchio, Franco; Basso, Alfonso; Milone, Francesco Ferro; Simoncini, Maria; Fiore, Cristina; Mattarello, Mee Joung; Sartorato, Paola; Karbowiak, Isabella

    2003-11-01

    Alzheimer's disease is often characterized by an increase in plasma cortisol without clinical evidence of hypercorticism. Twenty-three consecutive patients with Alzheimer's disease and 23 age- and sex-matched healthy controls were studied by measuring plasma cortisol and dehydroepiandrosterone sulfate (DHEAS) (by enzyme immunoassay), the number of type I and type II corticosteroid receptors in mononuclear leukocytes (by radio-receptor-assay), and the lymphocyte subpopulations (by cytofluorimetry). Results are expressed in terms of median and range. In Alzheimer's disease, plasma cortisol was higher than in controls (median 0.74, range 0.47-1.21 vs 0.47, 0.36-0.77 mmol/L; p < 0.001). Plasma DHEAS, the DHEAS/cortisol ratio, and the number of type II corticosteroid receptors were significantly lower in AD than in controls (DHEAS: median 1.81, range 0.21-3.69 vs 3.51, 1.35-9.07 micromol/L; DHEAS/ cortisol: 2.04, range 0.3-5.8 vs 6.8, range 2.7-24 and type II receptors: 1219, 1000-2700 vs 1950, 1035- 2750 receptors per cell; p < 0.001). No correlation was found between the hormonal parameters, age, and mini-mental test score. These data support the hypothesis of a dysregulation of the adrenal pituitary axis in Alzheimer's disease, which is probably the consequence of damage to target tissues by corticosteroids.

  17. High active nitrogen flux growth of GaN by plasma assisted molecular beam epitaxy

    SciTech Connect

    McSkimming, Brian M. Speck, James S.; Chaix, Catherine

    2015-09-15

    In the present study, the authors report on a modified Riber radio frequency (RF) nitrogen plasma source that provides active nitrogen fluxes more than 30 times higher than those commonly used for plasma assisted molecular beam epitaxy (PAMBE) growth of gallium nitride (GaN) and thus a significantly higher growth rate than has been previously reported. GaN films were grown using N{sub 2} gas flow rates between 5 and 25 sccm while varying the plasma source's RF forward power from 200 to 600 W. The highest growth rate, and therefore the highest active nitrogen flux, achieved was ∼7.6 μm/h. For optimized growth conditions, the surfaces displayed a clear step-terrace structure with an average RMS roughness (3 × 3 μm) on the order of 1 nm. Secondary ion mass spectroscopy impurity analysis demonstrates oxygen and hydrogen incorporation of 1 × 10{sup 16} and ∼5 × 10{sup 17}, respectively. In addition, the authors have achieved PAMBE growth of GaN at a substrate temperature more than 150 °C greater than our standard Ga rich GaN growth regime and ∼100 °C greater than any previously reported PAMBE growth of GaN. This growth temperature corresponds to GaN decomposition in vacuum of more than 20 nm/min; a regime previously unattainable with conventional nitrogen plasma sources. Arrhenius analysis of the decomposition rate shows that samples with a flux ratio below stoichiometry have an activation energy greater than decomposition of GaN in vacuum while samples grown at or above stoichiometry have decreased activation energy. The activation energy of decomposition for GaN in vacuum was previously determined to be ∼3.1 eV. For a Ga/N flux ratio of ∼1.5, this activation energy was found to be ∼2.8 eV, while for a Ga/N flux ratio of ∼0.5, it was found to be ∼7.9 eV.

  18. Plasma IMS Composition Measurements for Europa and Ganymede

    NASA Technical Reports Server (NTRS)

    Sittler, E.; Cooper, J.; Hartle, R.; Lipatov, A.; Mahaffy, P.; Paterson, W.; Paschalidis, N.; Coplan, M.; Cassidy, T.

    2010-01-01

    NASA and ESA are planning the joint Europa Jupiter System Mission (EJSM) to the Jupiter system with specific emphasis to Europa and Ganymede, respectively. The Japanese Space Agency is also planning an orbiter mission to explore Jupiter's magnetosphere and the Galilean satellites. For NASA's Jupiter Europa Orbiter (JEO) we are developing the 3D Ion Mass Spectrometer (IMS) with two main goals which can also be applied to the other Galilean moons, 1) measure the plasma interaction between Europa and Jupiter's magnetosphere and 2) infer the 4n surface composition to trace elemental [1] and significant isotopic levels. The first goal supports the magnetometer (MAG) measurements, primarily directed at detection of Europa's sub-surface ocean, while the second gives information about transfer of material between the Galilean moons, and between the moon surfaces and subsurface layers putatively including oceans. The measurement of the interactions for all the Galilean moons can be used to trace the in situ ion measurements of pickup ions back to either Europa's or Ganymede's surface from the respectively orbiting spacecraft. The IMS instrument, being developed under NASA's Astrobiology Instrument Development Program, would maximally achieve plasma measurement requirements for JEO and EJSM while moving forward our knowledge of Jupiter system composition and source processes to far higher levels than previously envisaged.

  19. Redeposition in plasma-assisted atomic layer deposition: Silicon nitride film quality ruled by the gas residence time

    NASA Astrophysics Data System (ADS)

    Knoops, Harm C. M.; de Peuter, K.; Kessels, W. M. M.

    2015-07-01

    The requirements on the material properties and growth control of silicon nitride (SiNx) spacer films in transistors are becoming ever more stringent as scaling of transistor structures continues. One method to deposit high-quality films with excellent control is atomic layer deposition (ALD). However, depositing SiNx by ALD has turned out to be very challenging. In this work, it is shown that the plasma gas residence time τ is a key parameter for the deposition of SiNx by plasma-assisted ALD and that this parameter can be linked to a so-called "redeposition effect". This previously ignored effect, which takes place during the plasma step, is the dissociation of reaction products in the plasma and the subsequent redeposition of reaction-product fragments on the surface. For SiNx ALD using SiH2(NHtBu)2 as precursor and N2 plasma as reactant, the gas residence time τ was found to determine both SiNx film quality and the resulting growth per cycle. It is shown that redeposition can be minimized by using a short residence time resulting in high-quality films with a high wet-etch resistance (i.e., a wet-etch rate of 0.5 nm/min in buffered HF solution). Due to the fundamental nature of the redeposition effect, it is expected to play a role in many more plasma-assisted ALD processes.

  20. Plasma IMS Composition Measurements for Europa and Ganymede

    NASA Astrophysics Data System (ADS)

    Sittler, E. C.; Cooper, J. F.; Hartle, R. E.; Paterson, W. R.; Lipatov, A. S.; Paschalidis, N. P.; Coplan, M. A.; Cassidy, T. A.

    2010-12-01

    NASA and ESA are planning the joint Europa Jupiter System Mission (EJSM) to the Jupiter system with specific emphases on Europa and Ganymede from these respective space agencies. The Japanese Space Agency is also planning an orbiter mission to explore Jupiter’s magnetosphere and the Galilean satellites. For NASA’s Jupiter Europa Orbiter (JEO) we are developing the 3D Ion Mass Spectrometer (IMS) with two main goals which can also be applied to the other Galilean moons, 1) measure the plasma interaction between Europa and Jupiter’s magnetosphere and 2) infer the 4π surface composition to trace elemental and significant isotopic levels. The first goal supports the magnetometer (MAG) measurements, primarily directed at detection of Europa’s sub-surface ocean, while the second gives information about transfer of material between the Galilean moons, and between the moon surfaces and subsurface layers putatively including oceans. The measurement of the interactions for all the Galilean moons can be used to trace the in situ ion measurements of pickup ions back to either Europa’s or Ganymede’s surface from the respectively orbiting spacecraft. The IMS instrument, being developed under NASA’s Astrobiology Instrument Development Program (ASTID), would maximally achieve plasma measurement requirements for JEO and EJSM while moving forward our knowledge of Jupiter system composition and source processes to far higher levels than previously envisaged. The ASTID-supported IMS, applicable to the NASA spacecraft, is designed to operate in a high radiation environment with minor and trace ion detection capability. The latter goal is achieved by measuring pickup ions at spacecraft altitudes and using a 3D hybrid model of the interaction in order to construct 3D global model of the electric and magnetic fields around these bodies. The pickup ion trajectories can then be traced back down to the surface. In the case of Europa we also show that Europa’s ionosphere is

  1. Hierarchical carbon nanowire microarchitectures made by plasma-assisted pyrolysis of photoresist.

    PubMed

    De Volder, Michaël F L; Vansweevelt, Rob; Wagner, Patrick; Reynaerts, Dominiek; Van Hoof, Chris; Hart, A John

    2011-08-23

    We present a new approach for the fabrication and integration of vertically aligned forests of amorphous carbon nanowires (CNWs), using only standard lithography, oxygen plasma treatment, and thermal processing. The simplicity and scalability of this process, as well as the hierarchical organization of CNWs, provides a potential alternative to the use of carbon nanotubes and graphene for applications in microsystems and high surface area materials. The CNWs are highly branched at the nanoscale, and novel hierarchical microstructures with CNWs connected to a solid amorphous core are made by controlling the plasma treatment time. By multilayer processing we demonstrate deterministic joining of CNW micropillars into 3D sensing networks. Finally we show that these networks can be chemically functionalized and used for measurement of DNA binding with increased sensitivity.

  2. Material measurement method based on femtosecond laser plasma shock wave

    NASA Astrophysics Data System (ADS)

    Zhong, Dong; Li, Zhongming

    2017-03-01

    The acoustic emission signal of laser plasma shock wave, which comes into being when femtosecond laser ablates pure Cu, Fe, and Al target material, has been detected by using the fiber Fabry-Perot (F-P) acoustic emission sensing probe. The spectrum characters of the acoustic emission signals for three kinds of materials have been analyzed and studied by using Fourier transform. The results show that the frequencies of the acoustic emission signals detected from the three kinds of materials are different. Meanwhile, the frequencies are almost identical for the same materials under different ablation energies and detection ranges. Certainly, the amplitudes of the spectral character of the three materials show a fixed pattern. The experimental results and methods suggest a potential application of the plasma shock wave on-line measurement based on the femtosecond laser ablating target by using the fiber F-P acoustic emission sensor probe.

  3. Spectroscopic measurements of high frequency plasma in supercritical carbon dioxide

    SciTech Connect

    Maehara, T.; Mukasa, S.; Takemori, T.; Watanabe, T.; Kurokawa, K.; Toyota, H.; Nomura, S.; Kawashima, A.; Iwamae, A.

    2009-03-15

    Spectroscopic measurements of high frequency (hf) plasma were performed under high pressure conditions (5 and 7 MPa) and supercritical (sc) CO{sub 2} conditions (8-20 MPa). Temperature evaluated from C{sub 2} Swan bands (d {sup 3}{pi}{sub g}{yields}a {sup 3}{pi}{sub u}) increased from 3600 to 4600 K with an increase in pressure. The first observation of broadening and shifting of the O I line profile (3p {sup 5} P{sub 3,2,1}{yields}3s {sup 5} S{sub 2}{sup 0}) of hf plasma under sc CO{sub 2} conditions was carried out. However, the origin of broadening and the shifting cannot be understood because the present theory explaining them is not valid for such high pressure conditions.

  4. Ionospheric plasma density irregularities measured by stimulated electromagnetic emission

    NASA Astrophysics Data System (ADS)

    Norin, L.; Grach, S. M.; Leyser, T. B.; Thidé, B.; Sergeev, E. N.; Berlin, M.

    2008-09-01

    It is well known that ionospheric plasma turbulence can be conveniently generated by controlled injection of powerful high-frequency radio beams from the ground. Irradiation of the ionosphere with such radio waves leads to the formation of plasma density structures, striations, and the generation of secondary electromagnetic radiation, a phenomenon known as stimulated electromagnetic emission (SEE). In this paper we present experimental results of the dependence of SEE on decreasing excitation levels of the striations. In the experiments the frequency of the injected radio beam was varied near the fifth harmonic of the local ionospheric electron gyro frequency. We use the SEE measurements to obtain transverse length scales of the striations involved in the generation of the SEE. Our results show that different spectral features of the SEE display different temporal dynamics, suggesting that they are related to striations with different transverse length scales (1 ≲ l⊥ ≲ 25 m).

  5. Measurable signatures of relativistic self-focusing in underdense plasmas

    SciTech Connect

    Gibbon, P.; Monot, P.; Auguste, T.; Mainfray, G.

    1995-04-01

    The propagation of intense, picosecond laser pulses in tenuous plasmas is studied for conditions close to those required for relativistic self-focusing. Solutions of the steady-state wave-envelope equations are used to obtain experimentally measurable quantities such as the Thomson-scattered light at 90{degree}, and the far-field radiation pattern. It is demonstrated that in the presence of electron cavitation, the Thomson signal has a longitudinal structure which is generally the converse of the intensity pattern. Furthermore, beam collimation in the far-field depends on where the laser is focused in the plasma, and may actually be degraded if self-channeling occurs. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  6. Measurements of Laser-Plasma Instability Relevant to Ignition Hohlraums

    NASA Astrophysics Data System (ADS)

    Fernández, Juan C.

    1996-11-01

    footnotetext[1]This work is supported by the US DOE. footnotetext[2]In collaboration with: B.S. Bauer, J.A. Cobble, D.F. DuBois, G.A. Kyrala, D.S. Montgomery, H.A. Rose, H.X. Vu, R.G. Watt, B.H. Wilde, M.D. Wilke, W.M. Wood, Los Alamos National Laboratory; R. Kirkwood, B.J. MacGowan, Lawrence Livermore National Laboratory; B.H. Failor, Physics International. Recent experimental observations contribute to a much better understanding of laser interactions with plasmas having the long scale lengths and high electron densities (n_e) and temperatures (T_e) expected within hohlraums designed to drive a fusion capsule to ignition. Some important effects being observed and explained theoretically are intimately related to the presence of hot spots in high-energy lasers. For example, measured onset intensities for strong stimulated Brillouin and Raman scattering (SBS and SRS) in various plasma conditions are consistent with predictions from models which include realistic hot-spot statistics. We also present direct experimental evidence that the combination of plasma flow transverse to a laser beam and self-focusing can deflect the beam, an effect unrelated to conventional refraction. In these plasmas, SRS could saturate at a level where the SRS Langmuir-wave amplitude is sufficiently high for it to be strongly unstable to parametric decay involving a daughter ion-acoustic wave. In support of this model, the measured SRS reflectivity depends on ion acoustic damping, which should otherwise be unrelated to SRS. This saturation mechanism is predicted to become ineffective at the highest Te and lowest ne values, where fortunately the calculated SRS onset intensity is highest and could exceed the desired laser intensity. The SBS and SRS light at the target plane can now be imaged to study correlations between SRS and SBS. The initial results from this study are also presented.

  7. In Situ Nanocalorimetric Investigations of Plasma Assisted Deposited Poly(ethylene oxide)-like Films by Specific Heat Spectroscopy.

    PubMed

    Madkou, Sherif; Melnichu, Iurii; Choukourov, Andrei; Krakovsky, Ivan; Biederman, Hynek; Schönhals, Andreas

    2016-04-28

    In recent years, highly cross-linked plasma polymers have started to unveil their potential in numerous biomedical applications in thin-film form. However, conventional diagnostic methods often fail due to their diverse molecular dynamics conformations. Here, glassy dynamics and the melting transition of thin PEO-like plasma assisted deposited (ppPEO) films (thickness 100 nm) were in situ studied by a combination of specific heat spectroscopy, utilizing a pJ/K sensitive ac-calorimeter chip, and composition analytical techniques. Different cross-linking densities were obtained by different plasma powers during the deposition of the films. Glassy dynamics were observed for all values of the plasma power. It was found that the glassy dynamics slows down with increasing the plasma power. Moreover, the underlying relaxation time spectra broaden indicating that the molecular motions become more heterogeneous with increasing plasma power. In a second set of the experiment, the melting behavior of the ppPEO films was studied. The melting temperature of ppPEO was found to decrease with increasing plasma power. This was explained by a decrease of the order in the crystals due to formation of chemical defects during the plasma process.

  8. Measurements of fusion reactions from a Tokamak plasma

    NASA Astrophysics Data System (ADS)

    Chrien, R. E.

    1981-11-01

    Tokamak fusion reaction diagnostics were extended to include measurements of d-t, dp-3He, and d-d (proton branch) reactions. The confinement and slowing down of 1 MeV d-d tritons were studied y measuring d-t meutrons. The first charged fusion products to be detected in a Tokamak were the 3 MeV d-d and 14.7 MeV d- 3He protons. Beam-target d-3He reactions were measured during deuterium beam injection to study the transport and vessel retention of helium. Large d-3He reaction rates were produced by ion cyclotron heating of a 3He minority in a deuterium plasma. Measurements of the reaction rate, energy spectrum, and decay time indicate that the reactions are produced by 200 - 400 keV3He ions. Sawtooth and m = 2 oscillations in the proton emission were observed.

  9. 10 CFR 455.111 - Applicant certifications for technical assistance and energy conservation measure grants to...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... for technical assistance programs and energy conservation measures, including renewable resource... 10 Energy 3 2010-01-01 2010-01-01 false Applicant certifications for technical assistance and energy conservation measure grants to institutions and coordinating agencies. 455.111 Section 455.111...

  10. RESNA Resource Guide for Assistive Technology Outcomes: Measurement Tools. Volume I.

    ERIC Educational Resources Information Center

    RESNA: Association for the Advancement of Rehabilitation Technology, Arlington, VA.

    This resource guide, the first of three volumes, lays out the fundamentals of outcome measurements for assistive technology. It includes the whys and hows of gathering data so that assistive technology practitioners can integrate outcomes measurement activities in their daily practice. Chapters include: (1) "Concepts and Rationale for…

  11. Kr II laser-induced fluorescence for measuring plasma acceleration.

    PubMed

    Hargus, W A; Azarnia, G M; Nakles, M R

    2012-10-01

    We present the application of laser-induced fluorescence of singly ionized krypton as a diagnostic technique for quantifying the electrostatic acceleration within the discharge of a laboratory cross-field plasma accelerator also known as a Hall effect thruster, which has heritage as spacecraft propulsion. The 728.98 nm Kr II transition from the metastable 5d(4)D(7/2) to the 5p(4)P(5/2)(∘) state was used for the measurement of laser-induced fluorescence within the plasma discharge. From these measurements, it is possible to measure velocity as krypton ions are accelerated from near rest to approximately 21 km/s (190 eV). Ion temperature and the ion velocity distributions may also be extracted from the fluorescence data since available hyperfine splitting data allow for the Kr II 5d(4)D(7/2)-5p(4)P(5/2)(∘) transition lineshape to be modeled. From the analysis, the fluorescence lineshape appears to be a reasonable estimate for the relatively broad ion velocity distributions. However, due to an apparent overlap of the ion creation and acceleration regions within the discharge, the distributed velocity distributions increase ion temperature determination uncertainty significantly. Using the most probable ion velocity as a representative, or characteristic, measure of the ion acceleration, overall propellant energy deposition, and effective electric fields may be calculated. With this diagnostic technique, it is possible to nonintrusively characterize the ion acceleration both within the discharge and in the plume.

  12. Kr II laser-induced fluorescence for measuring plasma acceleration

    NASA Astrophysics Data System (ADS)

    Hargus, W. A.; Azarnia, G. M.; Nakles, M. R.

    2012-10-01

    We present the application of laser-induced fluorescence of singly ionized krypton as a diagnostic technique for quantifying the electrostatic acceleration within the discharge of a laboratory cross-field plasma accelerator also known as a Hall effect thruster, which has heritage as spacecraft propulsion. The 728.98 nm Kr II transition from the metastable 5d4D7/2 to the 5p ^4P^circ _{5/2} state was used for the measurement of laser-induced fluorescence within the plasma discharge. From these measurements, it is possible to measure velocity as krypton ions are accelerated from near rest to approximately 21 km/s (190 eV). Ion temperature and the ion velocity distributions may also be extracted from the fluorescence data since available hyperfine splitting data allow for the Kr II 5d4D7/2-5p ^4P^circ _{5/2} transition lineshape to be modeled. From the analysis, the fluorescence lineshape appears to be a reasonable estimate for the relatively broad ion velocity distributions. However, due to an apparent overlap of the ion creation and acceleration regions within the discharge, the distributed velocity distributions increase ion temperature determination uncertainty significantly. Using the most probable ion velocity as a representative, or characteristic, measure of the ion acceleration, overall propellant energy deposition, and effective electric fields may be calculated. With this diagnostic technique, it is possible to nonintrusively characterize the ion acceleration both within the discharge and in the plume.

  13. X-Ray Opacity Measurements of Solid Density Plasmas

    NASA Astrophysics Data System (ADS)

    Wark, Justin; Preston, Thomas; Ciricosta, Orlando; Vinko, Sam; Hollebon, Patrick; Chung, Hyun-Kyung; Burian, Thomas; Chalupsky, Jaromir; Vozda, Vojtech; Hall, Frank; Spindloe, Christopher; Zastrau, Ulf; Dakovski, Georgi; Minitti, Michael

    2016-10-01

    Accurate opacity measurements of dense plasmas are scarce, in part owing to the difficulty in creating samples that are uniform in density and temperature, and the associated undertaking of an opacity measurement on a time-scale short compared with disassembly. Here we demonstrate that x-ray opacity information can be obtained from emissivity measurements of solid-density targets of varying but known thickness, irradiated by a sub-100-fsec x-ray pulse from LCLS. As the emission is generated by the creation of core-holes created by the FEL, and they are rapidly filled on a femtosecond time-scale, information is gleaned before any hydrodynamic motion. Comparision with simulations based on the SCFLY atomic-kinetics code reveal that the time-integrated emission data can provide a strong constraint on the opacity under well-defined conditions of density and temperature, and further demonstrate that the technique is relatively insensitive to x-ray pulse-length and spatial distribution. As an example we present measurements of the K-shell opacity of a solid-density magnesium plasma for all ion stages up to helium-like.

  14. Carrier concentration dependence of donor activation energy in n-type GaN epilayers grown on Si (1 1 1) by plasma-assisted MBE

    SciTech Connect

    Kumar, Mahesh; Bhat, Thirumaleshwara N.; Roul, Basanta; Rajpalke, Mohana K.; Kalghatgi, A.T.; Krupanidhi, S.B.

    2012-06-15

    Highlights: ► The n-type GaN layers were grown by plasma-assisted molecular beam epitaxy. ► The optical characteristics of a donor level in Si-doped GaN were studied. ► Activation energy of a Si-related donor was estimated from temperature dependent PL measurements. ► PL peak positions, FWHM of PL and activation energies are found to be proportional to the cube root of carrier density. ► The involvement of donor levels is supported by the temperature-dependent electron concentration measurements. -- Abstract: The n-type GaN layers were grown by plasma-assisted MBE and either intentionally doped with Si or unintentionally doped. The optical characteristics of a donor level in Si-doped, GaN were studied in terms of photoluminescence (PL) spectroscopy as a function of electron concentration. Temperature dependent PL measurements allowed us to estimate the activation energy of a Si-related donor from temperature-induced decay of PL intensity. PL peak positions, full width at half maximum of PL and activation energies are found to be proportional to the cube root of carrier density. The involvement of donor levels is supported by the temperature-dependent electron concentration measurements.

  15. Flowing dusty plasma experiments: generation of flow and measurement techniques

    NASA Astrophysics Data System (ADS)

    Jaiswal, S.; Bandyopadhyay, P.; Sen, A.

    2016-12-01

    A variety of experimental techniques for the generation of subsonic/supersonic dust fluid flows and means of measuring such flow velocities are presented. The experiments have been carried out in a \\Pi -shaped dusty plasma experimental device with micron size kaolin/melamine formaldehyde particles embedded in a background of argon plasma created by a direct current glow discharge. A stationary dust cloud is formed over the cathode region by precisely balancing the pumping speed and gas flow rate. A flow of dust particles/fluid is generated by additional gas injection from a single or dual locations or by altering the dust confining potential. The flow velocity is then estimated by three different techniques, namely, by super particle identification code, particle image velocimetry analysis and the excitation of dust acoustic waves. The results obtained from these three different techniques along with their merits and demerits are discussed. An estimation of the neutral drag force responsible for the generation as well as the attenuation of the dust fluid flow is made. These techniques can be usefully employed in laboratory devices to investigate linear and non-linear collective excitations in a flowing dusty plasma.

  16. Statistical analysis of plasma thermograms measured by differential scanning calorimetry.

    PubMed

    Fish, Daniel J; Brewood, Greg P; Kim, Jong Sung; Garbett, Nichola C; Chaires, Jonathan B; Benight, Albert S

    2010-11-01

    Melting curves of human plasma measured by differential scanning calorimetry (DSC), known as thermograms, have the potential to markedly impact diagnosis of human diseases. A general statistical methodology is developed to analyze and classify DSC thermograms to analyze and classify thermograms. Analysis of an acquired thermogram involves comparison with a database of empirical reference thermograms from clinically characterized diseases. Two parameters, a distance metric, P, and correlation coefficient, r, are combined to produce a 'similarity metric,' ρ, which can be used to classify unknown thermograms into pre-characterized categories. Simulated thermograms known to lie within or fall outside of the 90% quantile range around a median reference are also analyzed. Results verify the utility of the methods and establish the apparent dynamic range of the metric ρ. Methods are then applied to data obtained from a collection of plasma samples from patients clinically diagnosed with SLE (lupus). High correspondence is found between curve shapes and values of the metric ρ. In a final application, an elementary classification rule is implemented to successfully analyze and classify unlabeled thermograms. These methods constitute a set of powerful yet easy to implement tools for quantitative classification, analysis and interpretation of DSC plasma melting curves.

  17. Plasma formation and temperature measurement during single-bubble cavitation

    NASA Astrophysics Data System (ADS)

    Flannigan, David J.; Suslick, Kenneth S.

    2005-03-01

    Single-bubble sonoluminescence (SBSL) results from the extreme temperatures and pressures achieved during bubble compression; calculations have predicted the existence of a hot, optically opaque plasma core with consequent bremsstrahlung radiation. Recent controversial reports claim the observation of neutrons from deuterium-deuterium fusion during acoustic cavitation. However, there has been previously no strong experimental evidence for the existence of a plasma during single- or multi-bubble sonoluminescence. SBSL typically produces featureless emission spectra that reveal little about the intra-cavity physical conditions or chemical processes. Here we report observations of atomic (Ar) emission and extensive molecular (SO) and ionic (O2+) progressions in SBSL spectra from concentrated aqueous H2SO4 solutions. Both the Ar and SO emission permit spectroscopic temperature determinations, as accomplished for multi-bubble sonoluminescence with other emitters. The emissive excited states observed from both Ar and O2+ are inconsistent with any thermal process. The Ar excited states involved are extremely high in energy (>13eV) and cannot be thermally populated at the measured Ar emission temperatures (4,000-15,000K) the ionization energy of O2 is more than twice its bond dissociation energy, so O2+ likewise cannot be thermally produced. We therefore conclude that these emitting species must originate from collisions with high-energy electrons, ions or particles from a hot plasma core.

  18. Plasma formation and temperature measurement during single-bubble cavitation.

    PubMed

    Flannigan, David J; Suslick, Kenneth S

    2005-03-03

    Single-bubble sonoluminescence (SBSL) results from the extreme temperatures and pressures achieved during bubble compression; calculations have predicted the existence of a hot, optically opaque plasma core with consequent bremsstrahlung radiation. Recent controversial reports claim the observation of neutrons from deuterium-deuterium fusion during acoustic cavitation. However, there has been previously no strong experimental evidence for the existence of a plasma during single- or multi-bubble sonoluminescence. SBSL typically produces featureless emission spectra that reveal little about the intra-cavity physical conditions or chemical processes. Here we report observations of atomic (Ar) emission and extensive molecular (SO) and ionic (O2+) progressions in SBSL spectra from concentrated aqueous H2SO4 solutions. Both the Ar and SO emission permit spectroscopic temperature determinations, as accomplished for multi-bubble sonoluminescence with other emitters. The emissive excited states observed from both Ar and O2+ are inconsistent with any thermal process. The Ar excited states involved are extremely high in energy (>13 eV) and cannot be thermally populated at the measured Ar emission temperatures (4,000-15,000 K); the ionization energy of O2 is more than twice its bond dissociation energy, so O2+ likewise cannot be thermally produced. We therefore conclude that these emitting species must originate from collisions with high-energy electrons, ions or particles from a hot plasma core.

  19. Hugoniot measurements of double-shocked precompressed dense xenon plasmas.

    PubMed

    Zheng, J; Chen, Q F; Gu, Y J; Chen, Z Y

    2012-12-01

    The current partially ionized plasmas models for xenon show substantial differences since the description of pressure and thermal ionization region becomes a formidable task, prompting the need for an improved understanding of dense xenon plasmas behavior at above 100 GPa. We performed double-shock compression experiments on dense xenon to determine accurately the Hugoniot up to 172 GPa using a time-resolved optical radiation method. The planar strong shock wave was produced using a flyer plate impactor accelerated up to ∼6 km/s with a two-stage light-gas gun. The time-resolved optical radiation histories were acquired by using a multiwavelength channel optical transience radiance pyrometer. Shock velocity was measured and mass velocity was determined by the impedance-matching methods. The experimental equation of state of dense xenon plasmas are compared with the self-consistent fluid variational calculations of dense xenon in the region of partial ionization over a wide range of pressures and temperatures.

  20. Effects on plasma and electric field measurements induced by spacecraft-plasma interaction

    NASA Astrophysics Data System (ADS)

    Onishi, T.; Berthelier, J.-J.; Forest, J.; Marchand, R.

    2009-04-01

    The interaction between a moving spacecraft and the ambient plasma may induce significant disturbances on plasma and electric field measurements that need to be accurately taken into account in order to optimize the positioning of instruments and to correct the measurements. Two resulting effects are presented in this poster. The first one is related to bulk velocity measurements made onboard the DEMETER micro-satellite. Detailed calculation of the plasma sheath around the satellite have been made using the SPIS code developped under the responsibility of ESA in order to determine the possible effects of a non-plane ion sheath on the ion trajectories and the disturbance on their bulk velocity direction that is measured by the IAP ion analyzer. Results will be shown indicating that deviation of a few degree may be expected that need to be taken into account to interpret the observations. A second observation will be presented dealing with an unexpected effect of the distant wake of the satellite. An anomaly aligned along the dip equator in the pacific sector observed by the electric field instrument on board was found related to an anomalous potential increase in one of the 4 probe. The local magnetic field line passing through the probe intersects with the satellite's wake region at 30m behind, neglecting converging/diverging effects of ions' ram motion. A simple but fast 2D Particle-In-Cell code, with an FFT Poisson solver, is developed to estimate the distant wake effects on the electrons' motion along the magnetic field line through the affected probe. Results from the simulation will be presented and its effects on the anomalous potential increase on the probe will be discussed.

  1. Chemical characterization of PAN based carbon fibers produced by microwave assisted plasma (MAP) technology and effect of plasma treatment on carbon fiber surface and interphase with polymer matrix

    NASA Astrophysics Data System (ADS)

    Luo, Xiaoyu

    The first objective of this research was to chemically characterize the surface of conventional carbon fiber and carbon fiber produced by microwave assisted plasma (MAP) manufacturing process. The chemical composition and functional groups on the surface of the fibers were determined by X-ray photoelectron spectroscopy (XPS). The untreated unsized MAP carbon fibers were compared to untreated unsized conventional carbon fibers and showed a significant amount of oxygen. Comparison between treated unsized MAP carbon fiber and treated unsized conventional carbon fiber reveal a 100% enhancement of oxygen elemental concentration. Two plasma systems, remote applicator and atmospheric plasma were used to treat untreated unsized conventional carbon fiber. XPS results indicated that both systems have changed the chemical composition of carbon fiber surface. Oxygen-containing functional groups were found on carbon fiber surface after plasma treatment. Auger electron spectroscopy combining with chemical deritivazation was used to investigate the effect of morphological structure of carbon fiber surface on the placement of carboxyl groups. It was found that carboxyl groups were located preferentially in the valleys. A model of surface morphological structure of carbon fibers treated with plasma was proposed. Chemical bonding formed in the interphase between plasma treated carbon fiber and urethane was investigated using FTIR imaging. Directed evidence of formation of hydrogen bonding between carbon fiber and urethane was observed.

  2. Low-Temperature Plasma-Assisted Atomic Layer Deposition of Silicon Nitride Moisture Permeation Barrier Layers.

    PubMed

    Andringa, Anne-Marije; Perrotta, Alberto; de Peuter, Koen; Knoops, Harm C M; Kessels, Wilhelmus M M; Creatore, Mariadriana

    2015-10-14

    Encapsulation of organic (opto-)electronic devices, such as organic light-emitting diodes (OLEDs), photovoltaic cells, and field-effect transistors, is required to minimize device degradation induced by moisture and oxygen ingress. SiNx moisture permeation barriers have been fabricated using a very recently developed low-temperature plasma-assisted atomic layer deposition (ALD) approach, consisting of half-reactions of the substrate with the precursor SiH2(NH(t)Bu)2 and with N2-fed plasma. The deposited films have been characterized in terms of their refractive index and chemical composition by spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The SiNx thin-film refractive index ranges from 1.80 to 1.90 for films deposited at 80 °C up to 200 °C, respectively, and the C, O, and H impurity levels decrease when the deposition temperature increases. The relative open porosity content of the layers has been studied by means of multisolvent ellipsometric porosimetry (EP), adopting three solvents with different kinetic diameters: water (∼0.3 nm), ethanol (∼0.4 nm), and toluene (∼0.6 nm). Irrespective of the deposition temperature, and hence the impurity content in the SiNx films, no uptake of any adsorptive has been observed, pointing to the absence of open pores larger than 0.3 nm in diameter. Instead, multilayer development has been observed, leading to type II isotherms that, according to the IUPAC classification, are characteristic of nonporous layers. The calcium test has been performed in a climate chamber at 20 °C and 50% relative humidity to determine the intrinsic water vapor transmission rate (WVTR) of SiNx barriers deposited at 120 °C. Intrinsic WVTR values in the range of 10(-6) g/m2/day indicate excellent barrier properties for ALD SiNx layers as thin as 10 nm, competing with that of state-of-the-art plasma-enhanced chemical vapor-deposited SiNx layers of a few hundred

  3. Measurement of plasma-generated RONS in the cancer cells exposed by atmospheric pressure helium plasma jet

    NASA Astrophysics Data System (ADS)

    Joh, Hea Min; Baek, Eun Jeong; Kim, Sun Ja; Chung, Tae Hun

    2015-09-01

    The plasma-induced reactive oxygen and nitrogen species (RONS) could result in cellular responses including DNA damages and apoptotic cell death. These chemical species, O, O2-,OH, NO, and NO2-,exhibit strong oxidative stress and/or trigger signaling pathways in biological cells. Each plasma-generated chemical species having biological implication should be identified and quantitatively measured. For quantitative measurement of RONS, this study is divided into three stages; plasma diagnostics, plasma-liquid interactions, plasma-liquid-cell interactions. First, the optical characteristics of the discharges were obtained by optical emission spectroscopy to identify various excited plasma species. And the characteristics of voltage-current waveforms, gas temperature, and plume length with varying control parameters were measured. Next, atmospheric pressure plasma jet was applied on the liquid. The estimated OH radical densities were obtained by ultraviolet absorption spectroscopy at the liquid surface. And NO2-is detected by Griess test and compared between the pure liquid and the cell-containing liquid. Finally, bio-assays were performed on plasma treated human lung cancer cells (A549). Intracellular ROS production was measured using DCF-DA. Among these RONS, productions of NO and OH within cells were measured by DAF-2DA and APF, respectively. The data are very suggestive that there is a strong correlation among the production of RONS in the plasmas, liquids, and cells.

  4. Creating an Assistive Technology Outcomes Measurement System: Validating the Components

    ERIC Educational Resources Information Center

    Edyburn, Dave L.; Smith, Roger O.

    2004-01-01

    The topic of assistive technology (AT) outcomes has only recently received attention in the professional literature. As a result, there is a considerable void in the profession's ability to address contemporary questions about the value and use of AT. The purpose of this article is to highlight the theory, development, and research efforts of the…

  5. Some Measurement and Instruction Related Considerations Regarding Computer Assisted Testing.

    ERIC Educational Resources Information Center

    Oosterhof, Albert C.; Salisbury, David F.

    The Assessment Resource Center (ARC) at Florida State University provides computer assisted testing (CAT) for approximately 4,000 students each term. Computer capabilities permit a small proctoring staff to administer tests simultaneously to large numbers of students. Programs provide immediate feedback for students and generate a variety of…

  6. Measuring Student Achievement in Home Health Assisting. Health Occupations Education.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany.

    The Home Health Assisting (HHA) program was developed specifically for use by educational agencies which offer a program in HHA upon approval granted by New York State Education Department through the Joint State Agency review and approval process. It is designed to prepare adults for work in the home under supervision of a health-care agency. A…

  7. Rotation of plasma membrane proteins measured by polarized fluorescence depletion

    NASA Astrophysics Data System (ADS)

    Barisas, B. George; Rahman, Noorul A.; Yoshida, Thomas M.; Roess, Deborah A.

    1990-05-01

    We have implemented a new laser microscopic method, polarized fluorescence depletion (PFD), for measuring the rotational dynamics of functional membrane proteins on individual, microscopically selected cells under physiological conditions. This method combines the long lifetimes of triplet-state probes with the sensitivity of fluorescence detection to measure macromolecular rotational correlation times from 10 microsec to > 1 ms. As examples, the rotational correlation time of Fc receptors (FcR) on the surface of 2H3 rat basophilic leukemia cells is 79.9 4.4 microsec at 4°C when labeled with eosin conjugates of IgE. This value is consistent with the known 100 kDa receptor size. When labeled with intact F4 anti-FcR monoclonal antibody, the rotational correlation time for FcER is increased about 2-fold to 170.8 +/- 6.5 microsec, consistent with receptor dimer formation on the plasma membrane and with the ability of this antibody to form FcER dimers on 2H3 cell surfaces. We have also examined the rotational diffusion of the luteinizing hormone receptor on plasma membranes of small ovine luteal cells. Luteinizing hormone receptors (LHR), when occupied by ovine luteinizing hormone (oLH), have a rotational correlation time of 20.5 +/- 0.1 microsec at 4°C. When occupied by human chorionic gonadotropin (hCG), LHR have a rotational correlation time of 46.2 +/- 0.4 microsec suggesting that binding of hCG triggers additional LHR interactions with plasma membrane proteins. Together these studies suggest the utility of PFD measurements in assessing molecular size and molecular association of membrane proteins on individual cells. Relative advantages of time- and frequency-domain implementations of PFD are also discussed.

  8. Technical pitfalls in measurement of venous plasma NH3 concentration.

    PubMed

    Gerron, G G; Ansley, J D; Isaacs, J W; Kutner, M H; Rudman, D

    1976-05-01

    Measurement of venous plasma NH3 in normal subjects by the ion-exchange method of Forman [Clin. Chem. 10, 497 (1964)] in a hospital clinical laboratory gave a mean value of 640 mug/liter (range, 300-1320 mug/liter; intraassay, intra-individual, and inter-individual coefficients of variation, 8, 47, and 47%, respectively). The following conditions adversely affect the reproducibility of the test: pollution of laboratory atmosphere and glassware by NH3-containing detergents; smoking by patient or analyst; delay, turbulence, or use of heparin lock in venipuncture; delay or warming of plasma above degrees C before mixing it with resin; and delay in colorimetric analysis of resin eluate. When these sources of error were eliminated, the mean value for normals was reduced to 330 mug/liter, the range was narrowed to 220-470 mug/liter, and the above-mentioned CV's were 5, 16, and 17%, respectively. With the precautions cited, furthermore, the intra-assay and intra-individual CV's for fasting NH3 concentration in cirrhotic patients were similarly reduced. An NH3 tolerance test was done by administering a standard dose of NH4Cl to patients and measuring venous plasma NH3 at 0, 15, 30, 60, and 90 min; the NH3 tolerance was quantified from the area under the curve relating concentration to time (mug - min/liter). As measured in the clinical laboratory, NH3 tolerance of cirrhotic patients showed intra-assay and intra-individual CV's of 50 to 90%. When the tolerance tests were repeated in the same subjects with the laboratory precautions listed above, these CV's were reduced to 8-15%.

  9. Rotation Rate of Saturn's Magnetosphere using CAPS Plasma Measurements

    NASA Technical Reports Server (NTRS)

    Sittler, E.; Cooper, J.; Hartle, R.; Simpson, D.; Johnson, R.; Thomsen, M.; Arridge, C.

    2011-01-01

    We present the present status of an investigation of the rotation rate of Saturn's magnetosphere using a 3D velocity moment technique being developed at Goddard which is similar to the 2D version used by Sittler et al. for SOI and similar to that used by Thomsen et al.. This technique allows one to nearly cover the full energy range of the Cassini Plasma Spectrometer (CAPS) IMS from 1 V . E/Q < 50 kV. Since our technique maps the observations into a local inertial frame, it does work during roll maneuvers. We make comparisons with the bi-Maxwellian fitting technique developed by Wilson et al. and the similar velocity moment technique by Thomsen et al. . We concentrate our analysis when ion composition data is available, which is used to weight the non-compositional data, referred to as singles data, to separate H+, H2+ and water group ions (W+) from each other. The chosen periods have high enough telemetry rates (4 kbps or higher) so that coincidence ion data, similar to that used by Sittler et al. for SOI is available. The ion data set is especially valuable for measuring flow velocities for protons, which are more difficult to derive using singles data within the inner magnetosphere, where the signal is dominated by heavy ions (i.e., proton peak merges with W+ peak as low energy shoulder). Our technique uses a flux function, which is zero in the proper plasma flow frame, to estimate fluid parameter uncertainties. The comparisons investigate the experimental errors and potential for systematic errors in the analyses, including ours. The rolls provide the best data set when it comes to getting 4PI coverage of the plasma but are more susceptible to time aliasing effects. In the future we will then make comparisons with magnetic field observations, Saturn ionosphere conductivities as presently known and the field aligned currents necessary for the planet to enforce corotation of the rotating plasma.

  10. In situ and laboratory measurements of cold plasmas

    NASA Astrophysics Data System (ADS)

    Frederick-Frost, Kristen Mae

    Measurement of the ionospheric thermal particle population bridges the two different communities of ground-based radar and space-based rocket studies, which have the common goal of characterizing heavy ion transport in the cusp/cleft region. We report on the results of the SERSIO (Svalbard EISCAT Rocket Study of Ion Outflows) mission, which show broad-band-extremely-low-frequency wave-ion heating in an environment observed by the EISCAT (European Incoherent Scatter) radars to have enhanced thermal electron temperature and density, and inferred ion-acoustic activity. The SERSIO data raise questions about the effects of spacecraft charging and sheath formation on thermal particle data analysis. These questions determined the design requirements for a low energy laboratory plasma calibration facility which we built and have begun to use. We discuss the magnetron-based cylindrical resonant plasma source, which produces charged particles with ionospheric energies and densities. The plasmas created with this source have Debye lengths similar to those encountered on ionospheric rocket flights, creating an ideal environment for charging and sheath studies that inform future thermal flight detector design. We investigate electron sheath structures by varying ion to electron collection ratios. The non-monotonic electron sheaths obtained by embedding a positively biased electrode within the sheath of a more negative conductor are explored. These initial plasma ion and electron sheath investigations both clarify the behavior of a thermal electron detector previously flown, and explore a low density and long Debye length parameter regime that is under-studied in the laboratory.

  11. A new probe for measuring small electric fields in plasmas

    NASA Technical Reports Server (NTRS)

    Stenzel, R. L.

    1991-01-01

    A dipolar double probe has been developed for in situ measurements of small electric fields in laboratory plasmas. The probe measures dc to ac electric fields (f values between 0 and 20 MHz) with high sensitivity (Emin about 10 microV/cm) and responds to both space charge electric fields and inductive electric fields. Using voltage-to-frequency conversion, the probe signal is obtained free of errors and loading effects by a transmission line. Various examples of useful applications for the new probe are presented, such as measurements of dc ambipolar fields, ac space-charge fields of ion acoustic waves, ac inductive fields of whistler waves, and mixed inductive and space-charge electric fields in current-carrying magnetoplasmas.

  12. On bias of kinetic temperature measurements in complex plasmas

    SciTech Connect

    Kantor, M.; Moseev, D.; Salewski, M.

    2014-02-15

    The kinetic temperature in complex plasmas is often measured using particle tracking velocimetry. Here, we introduce a criterion which minimizes the probability of faulty tracking of particles with normally distributed random displacements in consecutive frames. Faulty particle tracking results in a measurement bias of the deduced velocity distribution function and hence the deduced kinetic temperature. For particles with a normal velocity distribution function, mistracking biases the obtained velocity distribution function towards small velocities at the expense of large velocities, i.e., the inferred velocity distribution is more peaked and its tail is less pronounced. The kinetic temperature is therefore systematically underestimated in measurements. We give a prescription to mitigate this type of error.

  13. Boom accomodation effects on plasma and field measurements with RPWI

    NASA Astrophysics Data System (ADS)

    Cervantes Correa, P.; Eriksson, A. I.; Wahlund, J.-E.; Odelstad, E.; Vaivads, A.; Bergman, J.

    2013-09-01

    While the JUICE spacecraft configuration and main contractor are yet to be decided, it is still possible to investigate general issues on the impact of various boom accomodation alternatives for measurements of plasma and electric fields using the Langmuir probe system of the Radio and Plasma Waves Investigation. These probes can be used as classical Langmuir probes, as electric field probes, or for mutual impedance measurements, and the impact of e.g. varying illumination and wake interference are different for each type of measurement. While there is a nominal JUICE trajectory for the main science mission, we have to do assumptions on the spacecraft pointing, e.g. nadir pointing during flybys of the various moons. The detailed spacecraft layout is not known, but we can arrive at general conclusions on the suitability of various boom accomodations by assuming a cube-like spacecraft with solar panels as rectangular wings. For disturbing structures like wakes and photoelectron clouds we use simple models based on previous simulations. Even though the detailed pointing and spacecraft design will quite certainly deviate from our assumptions, and the model has uncertainties also in other respects, we can still give some general conclusions on boom accomodation alternatives.

  14. Measurement of the dynamo effect in a plasma

    SciTech Connect

    Ji, H.; Prager, S.C.; Almagri, A.F.; Sarff, J.S.; Hirano, Y.; Toyama, H.

    1995-11-01

    A series of the detailed experiments has been conducted in three laboratory plasma devices to measure the dynamo electric field along the equilibrium field line (the {alpha} effect) arising from the correlation between the fluctuating flow velocity and magnetic field. The fluctuating flow velocity is obtained from probe measurement of the fluctuating E x B drift and electron diamagnetic drift. The three major findings are (1) the {alpha} effect accounts for the dynamo current generation, even in the time dependence through a ``sawtooth`` cycle; (2) at low collisionality the dynamo is explained primarily by the widely studied pressureless Magnetohydrodynamic (MHD) model, i.e., the fluctuating velocity is dominated by the E x B drift; (3) at high collisionality, a new ``electron diamagnetic dynamo`` is observed, in which the fluctuating velocity is dominated by the diamagnetic drift. In addition, direct measurements of the helicity flux indicate that the dynamo activity transports magnetic helicity from one part of the plasma to another, but the total helicity is roughly conserved, verifying J.B. Taylor`s conjecture.

  15. Hollow cathode and thruster discharge chamber plasma measurements

    NASA Technical Reports Server (NTRS)

    Jameson, Kristina K.; Goebel, Dan M.; Watkins, Ron M.

    2005-01-01

    Due to the successful performance of the NSTAR ion thruster in Deep Space 1 mission, coupled with the recently completed 30,352 hour extended life test (ELT) of the NSTAR flight spare thruster, ion thrusters have become a viable option for future NASA missions. In this paper, detailed measurements of the plasma parameters internal and external to the cathode will presented for the NSTAR cathode up to 13.1A of discharge current and for the NEXIS cathode up to 30A of discharge current.

  16. Measurements of electron number density and plasma temperature using LIBS

    NASA Astrophysics Data System (ADS)

    Zhao, Xiao-xia; Luo, Wen-feng; He, Jun-fang; Wang, Hong-ying; Yang, Sen-lin; Li, Yuan-yuan

    2016-10-01

    Plasma produced by the radiation of a 1064 nm Nd:YAG laser focused onto a standard aluminum alloy E311 was studied spectroscopically. The electron density was inferred by measuring the Stark broadened line profile of Cu I 324.75 nm at a distance of 1.5 mm from the target surface with the laser irradiance of 3.27 GW/cm2. The electron temperature was determined using the Boltzmann plot method with eight neutral iron lines. At the same time, the validity of the assumption of local thermodynamic equilibrium was discussed in light of the results obtained.

  17. Nighttime temperatures and ion chemistry from OGO 6 plasma measurements

    NASA Technical Reports Server (NTRS)

    Sanatani, S.; Breig, E. L.

    1980-01-01

    Results are presented of a statical investigation of temperature and molecular ion chemistry in the nighttime thermosphere, with data from plasma measurements between 400 and 450 km from the retarding potential analyzer on the OGO 6 satellite. Temperatures and ion concentrations from the equatorial region are discussed. Emphasis is placed on statistical analyses of all data acquired within small cells of finite width in latitude and day of observation. Attention is given to a significant fraction of the nighttime hemisphere between low summer and middle winter latitudes.

  18. Plasma-assisted molecular beam epitaxy growth of ZnSnN2

    NASA Astrophysics Data System (ADS)

    Feldberg, Nathaniel; Aldous, James; Yao, Yuan; Tanveer, Imtiaz; Keen, Benjamin; Linhart, Wojciech; Veal, Tim; Song, Young-Wook; Reeves, Roger; Durbin, Steve

    2012-02-01

    The Zn-IV-nitrides are a promising series of ``earth abundant element'' semiconductors with a predicted band gap range of 0.6 eV to 5.4 eV, which, like the (Al,Ga,In)N family, spans the entire visible solar spectrum. Considering this alternative family has a number of advantages, including the avoidance of indium, the price of which has varied almost an order of magnitude over the past decade, and surface electron accumulation which is present in the In-rich alloys. Not all members of this family have yet been synthesized, in particular ZnSnN2, the most important member for PV with its predicted band gap of approximately 2 eV. We have successfully grown a series of these films using plasma-assisted molecular beam epitaxy using elemental Zn and Sn sources. In this report, we discuss the relationship between process parameters and microstructure, as well as stoichiometry as determined by Rutherford backscattering spectrometry. Additionally, we provide preliminary estimates for its bandgap energy based on photoluminescence and optical absorption.

  19. Microwave plasma-assisted chemical vapor deposition of porous carbon film as supercapacitive electrodes

    NASA Astrophysics Data System (ADS)

    Wu, Ai-Min; Feng, Chen-Chen; Huang, Hao; Paredes Camacho, Ramon Alberto; Gao, Song; Lei, Ming-Kai; Cao, Guo-Zhong

    2017-07-01

    Highly porous carbon film (PCF) coated on nickel foam was prepared successfully by microwave plasma-assisted chemical vapor deposition (MPCVD) with C2H2 as carbon source and Ar as discharge gas. The PCF is uniform and dense with 3D-crosslinked nanoscale network structure possessing high degree of graphitization. When used as the electrode material in an electrochemical supercapacitor, the PCF samples verify their advantageous electrical conductivity, ion contact and electrochemical stability. The test results show that the sample prepared under 1000 W microwave power has good electrochemical performance. It displays the specific capacitance of 62.75 F/g at the current density of 2.0 A/g and retains 95% of its capacitance after 10,000 cycles at the current density of 2.0 A/g. Besides, its near-rectangular shape of the cyclic voltammograms (CV) curves exhibits typical character of an electric double-layer capacitor, which owns an enhanced ionic diffusion that can fit the requirements for energy storage applications.

  20. Growth of diamond by RF plasma-assisted chemical vapor deposition

    NASA Technical Reports Server (NTRS)

    Meyer, Duane E.; Ianno, Natale J.; Woollam, John A.; Swartzlander, A. B.; Nelson, A. J.

    1988-01-01

    A system has been designed and constructed to produce diamond particles by inductively coupled radio-frequency, plasma-assisted chemical vapor deposition. This is a low-pressure, low-temperature process used in an attempt to deposit diamond on substrates of glass, quartz, silicon, nickel, and boron nitride. Several deposition parameters have been varied including substrate temperature, gas concentration, gas pressure, total gas flow rate, RF input power, and deposition time. Analytical methods employed to determine composition and structure of the deposits include scanning electron microscopy, absorption spectroscopy, scanning Auger microprobe spectroscopy, and Raman spectroscopy. Analysis indicates that particles having a thin graphite surface, as well as diamond particles with no surface coatings, have been deposited. Deposits on quartz have exhibited optical bandgaps as high as 4.5 eV. Scanning electron microscopy analysis shows that particles are deposited on a pedestal which Auger spectroscopy indicates to be graphite. This is a phenomenon that has not been previously reported in the literature.

  1. Voltage-gated ion transport through semiconducting conical nanopores formed by metal nanoparticle assisted plasma etching

    PubMed Central

    James, Teena; Kalinin, Yevgeniy V.; Chan, Chih-Chieh; Randhawa, Jatinder S.; Gaevski, Mikhail

    2012-01-01

    Nanopores with conical geometries have been found to rectify ionic current in electrolytes. While nanopores in semiconducting membranes are known to modulate ionic transport through gated modification of pore surface charge, the fabrication of conical nanopores in silicon (Si) has proven challenging. Here, we report the discovery that gold (Au) nanoparticle (NP) assisted plasma etching results in the formation of conical etch profiles in Si. These conical profiles result due to enhanced Si etch rates in the vicinity of the Au NPs. We show that this process provides a convenient and versatile means to fabricate conical nanopores in Si membranes and crystals with variable pore-diameters and coneangles. We investigated ionic transport through these pores and observed that rectification ratios could be enhanced by a factor of over 100 by voltage gating alone, and that these pores could function as ionic switches with high on-off ratios of approximately 260. Further, we demonstrate voltage gated control over protein transport, which is of importance in lab-on-a-chip devices and biomolecular separations. PMID:22725714

  2. Plasma-Assisted Growth of Silicon Nanowires by Sn Catalyst: Step-by-Step Observation

    NASA Astrophysics Data System (ADS)

    Tang, Jian; Maurice, Jean-Luc; Chen, Wanghua; Misra, Soumyadeep; Foldyna, Martin; Johnson, Erik V.; Roca i Cabarrocas, Pere

    2016-10-01

    A comprehensive study of the silicon nanowire growth process has been carried out. Silicon nanowires were grown by plasma-assisted-vapor-solid method using tin as a catalyst. We have focused on the evolution of the silicon nanowire density, morphology, and crystallinity. For the first time, the initial growth stage, which determines the nanowire (NW) density and growth direction, has been observed step by step. We provide direct evidence of the merging of Sn catalyst droplets and the formation of Si nanowires during the first 10 s of growth. We found that the density of Sn droplets decreases from 9000 Sn droplets/μm2 to 2000 droplets/μm2 after just 10 s of growth. Moreover, the long and straight nanowire density decreases from 170/μm2 after 2 min of growth to less than 10/μm2 after 90 min. This strong reduction in nanowire density is accompanied by an evolution of their morphology from cylindrical to conical, then to bend conical, and finally, to a bend inverted conical shape. Moreover, the changes in the crystalline structure of nanowires are from (i) monocrystalline to (ii) monocrystalline core/defective crystalline shell and then to (iii) monocrystalline core/defective crystalline shell/amorphous shell. The evolutions of NW properties have been explained in detail.

  3. Dielectric barrier discharge for multi-point plasma-assisted ignition at high pressures.

    PubMed

    Shcherbanev, S A; Stepanyan, S A; Popov, N A; Starikovskaia, S M

    2015-08-13

    Nanosecond surface dielectric barrier discharge (nSDBD) is an efficient tool for a multi-point plasma-assisted ignition of combustible mixtures at elevated pressures. The discharge develops as a set of synchronously propagated from the high-voltage electrode charged channels (streamers), with a typical density up to a few streamers per millimetre of the length of the electrode. In combustible mixtures, nSDBD initiates numerous combustion waves propagating from the electrode. Very little is known about nSDBD at high pressures. This work presents a comparative experimental study of the surface dielectric barrier discharge initiated by high-voltage pulses (U=±(20-60) kV) of different polarities in air at elevated pressures (P=1-6 atm). Discharge morphology, deposited energy and velocity of the discharge front propagation are analysed. Differences between the discharges of positive and negative polarity, as well as the changes in the discharge morphology with changing of a gas mixture composition.

  4. Plasma-assisted low energy N2 implant for Vfb tuning of Ge gate stacks

    NASA Astrophysics Data System (ADS)

    Kothari, Shraddha; Joishi, Chandan; Nejad, Hasan; Variam, Naushad; Lodha, Saurabh

    2016-08-01

    This work reports Vfb tuning of TiN/HfO2 gate stacks on Ge using low energy plasma-assisted doping with N2 without significant impact on gate capacitance and gate/channel interface trap densities. As required for multi-VT Ge p-FinFETs, controlled change in effective work function up to 180 mV from the near midgap to the near valence band edge of Ge is demonstrated by varying implant dose and energy. Unlike Si gate stacks, increased gate leakage in implanted Ge gate stacks is shown to result from traps created in the HfO2 layer during the implant and exposed to channel carriers due to a low band offset GeO2 interfacial layer (IL). Recovery of gate leakage is demonstrated by substituting GeO2 with an Al2O3 IL. Further, a simple physical model is proposed to extract the work function and oxide charge components of the change in Vfb for varying implant doses and energies.

  5. Synthesis and characterization of carbon-encapsulated magnetic nanoparticles via arc-plasma assisted CVD.

    PubMed

    Li, Zhentao; Hu, Chao; Yu, Chang; Qiu, Jieshan

    2009-12-01

    Carbon-encapsulated magnetic nanoparticles (CEMNs) were fabricated on a large scale by arc-plasma assisted CVD in acetylene. The coal-derived metal-containing (Fe, Co and Ni) carbon rods were used as anodes, while a high-purity graphite rod was used as a cathode that remained unchanged during the arcing process. The CEMNs obtained were characterized by TEM, XRD, Raman spectroscopy, N2 adsorption isotherms and VSM. The diameter distribution of the obtained CEMNs varies from 10 to 70 nm, of which the metal cores are proximately 5-50 nm. The core phases in Fe(C) nanoparticles are body-centered cubic Fe and orthorhombic Fe3C while Co(C) nanoparticles and Ni(C) nanoparticles show the characteristic of a face-centered cubic structure. The Fe(C), Co(C) and Ni(C) nanoparticles with well-ordered graphitic shells have the surface area of 89 m2/g, 72 m2/g and 75 m2/g, respectively. The CEMNs show ferromagnetic of which was characterized by a ratio of remnant magnetization (MR) to saturation magnetization (MS).

  6. Nitride-based laser diodes grown by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Skierbiszewski, C.; Turski, H.; Muziol, G.; Siekacz, M.; Sawicka, M.; Cywiński, G.; Wasilewski, Z. R.; Porowski, S.

    2014-02-01

    The progress in the growth of nitride-based laser diodes (LDs) made by plasma-assisted molecular beam epitaxy (PAMBE) is reviewed. In this work we describe the GaN and InGaN growth peculiarities, p-type doping efficiency, and the properties of InGaN quantum wells (QWs) grown by PAMBE. We demonstrate continuous wave (cw) LDs operating in the range from 410 to 482 nm. These LDs were grown on low dislocation (0 0 0 1) c-plane bulk GaN substrate, which allow one to fabricate cw LDs with a lifetime exceeding 2000 h. Also, the ultraviolet LDs at 388 nm grown on (2 0 -2 1) semipolar substrates are discussed. The use of high active nitrogen fluxes up to 2 µm/h during the InGaN growth was essential for pushing the lasing wavelengths of PAMBE LDs above 460 nm. Recent advancement of InGaN growth by PAMBE allows one to demonstrate high-quality quantum QWs and excellent morphology for thick layers. We discuss the influence of LDs design on their parameters such as lasing threshold current and laser beam quality.

  7. A review on plasma-assisted VLS synthesis of silicon nanowires and radial junction solar cells

    NASA Astrophysics Data System (ADS)

    Misra, Soumyadeep; Yu, Linwei; Chen, Wanghua; Foldyna, Martin; Cabarrocas, Pere Roca i.

    2014-10-01

    Incorporation of nanostructures is a recent trend in the photovoltaic community, aimed at improving light absorption and consequently cell efficiency. In this regard, semiconductor nanowires provide an attractive research platform for a new generation of cost-effective and efficient solar cells. Thanks to their unique geometry, silicon nanowires enhance light trapping and anti-reflection effects by means of multiple scattering between individual nanowires, and by coupling the light into confined eigenmodes over a broad range of the solar spectrum. Moreover, radial junction solar cells built around nanowires decouple the light absorption and carrier collection directions, which allows for a higher internal field and better carrier collection. Thus, arrays of radial junction solar cells bring advantages of high efficiency with reduced material amount. This is particularly attractive for devices based on hydrogenated amorphous and microcrystalline silicon thin films. In this paper, after reviewing different approaches to fabricate silicon nanowires, we focus on nanowires grown using the plasma-assisted vapour-liquid-solid method because of the simplicity and compatibility with current silicon thin-film technology. Their application to a-Si : H based radial junction solar cells has already resulted in ˜8% of stable devices with an absorber layer thickness of only 100 nm. Moreover, current challenges and perspectives such as the use of a microcrystalline silicon absorber are also reviewed.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  9. Integration of plasma-assisted surface chemical modification, soft lithography, and protein surface activation for single-cell patterning

    NASA Astrophysics Data System (ADS)

    Cheng, Q.; Komvopoulos, K.

    2010-07-01

    Surface patterning for single-cell culture was accomplished by combining plasma-assisted surface chemical modification, soft lithography, and protein-induced surface activation. Hydrophilic patterns were produced on Parylene C films deposited on glass substrates by oxygen plasma treatment through the windows of polydimethylsiloxane shadow masks. After incubation first with Pluronic F108 solution and then serum medium overnight, surface seeding with mesenchymal stem cells in serum medium resulted in single-cell patterning. The present method provides a means of surface patterning with direct implications in single-cell culture.

  10. Theory and measurements of emittance preservation in plasma wakefield acceleration

    SciTech Connect

    Frederico, Joel

    2016-12-01

    In this dissertation, we examine the preservation and measurement of emittance in the plasma wakefield acceleration blowout regime. Plasma wakefield acceleration (PWFA) is a revolutionary approach to accelerating charged particles that has been demonstrated to have the potential for gradients orders of magnitude greater than traditional approaches. The application of PWFA to the design of a linear collider will make new high energy physics research possible, but the design parameters must first be shown to be competitive with traditional methods. Emittance preservation is necessary in the design of a linear collider in order to maximize luminosity. We examine the conditions necessary for circular symmetry in the PWFA blowout regime, and demonstrate that current proposals meet these bounds. We also present an application of beam lamentation which describes the process of beam parameter and emittance matching. We show that the emittance growth saturates as a consequence of energy spread in the beam. The initial beam parameters determine the amount of emittance growth, while the contribution of energy spread is negligible. We also present a model for ion motion in the presence of a beam that is much more dense than the plasma. By combining the model of ion motion and emittance growth, we find the emittance growth due to ion motion is minimal in the case of marginal ion motion. In addition, we present a simulation that validates the ion motion model, which is under further development to examine emittance growth of both marginal and pronounced ion motion. Finally, we present a proof-of-concept of an emittance measurement which may enable the analysis of emittance preservation in future PWFA experiments.

  11. Growth of high quality N-polar AlN(0001xAF) on Si(111) by plasma assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Dasgupta, Sansaptak; Wu, F.; Speck, J. S.; Mishra, U. K.

    2009-04-01

    High quality N-polar AlN epilayers were grown and characterized on Si(111) substrates by plasma assisted molecular beam epitaxy as a first step toward growth of N-polar nitrides on Si(111). Polarity inversion to N-face by an optimized predeposition of Al adatoms on the reconstructed 7×7 Si(111) surface was investigated. Al adatoms can saturate the dangling bonds of Si atoms, resulting in growth of AlN in (0001¯) direction on subsequent exposure to N2 plasma. N-polarity was confirmed by observing strong 3×3 and 6×6 reflection high-energy electron diffraction reconstructions, convergent beam electron diffraction imaging and KOH etching studies. The structural properties were investigated by x-ray diffraction measurements, cross section and plan-view TEM studies.

  12. Boron nitride phosphide thin films grown on quartz substrate by hot-filament and plasma-assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Zhang, X. W.; Xu, S. Y.; Han, G. R.

    2004-10-01

    Boron nitride phosphide films are, for the first time, grown on transparent quartz substrate by hot filament and radio-frequency plasma co-assisted chemical vapor deposition technique. XPS, XRD, SEM, and UV measurements are performed to study the chemical composition, crystallization, microstructure, and optical absorption, respectively. A centipede-like microstructure and undulating ground morphology on the film surface are observed, and their growth mechanism is speculated upon. The chemical composition is determined as BN1-xPx, whose characteristic XRD peak is preliminarily identified. The optical band gap can be modulated between 5.52 eV and 3.74 eV, simply by adjusting the phosphorus content in BN1-xPx through modifying the PH3 flux during the film-deposition process. The merits of the BN1-xPx film, such as high ultraviolet photoelectric sensitivity with negligible sensitivity in the visible region, modifiable wide optical band gap, and good adhesion on transparent substrate, suggest potential applications for ultraviolet photo-electronics.

  13. Composition and luminescence of AlInGaN layers grown by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Bejtka, K.; Edwards, P. R.; Martin, R. W.; Fernandez-Garrido, S.; Calleja, E.

    2008-10-01

    A study of AlInGaN epilayers, grown by plasma-assisted molecular beam epitaxy, was performed using spatially resolved x-ray microanalysis and luminescence spectroscopy in order to investigate competition between the incorporation of In, Al, and Ga as a function of the growth temperature in the 565-660 deg. C range and the nominal AlN mole fraction. The samples studied have AlN and InN mole fractions in the ranges of 4%-30% and 0%-16%, respectively. Composition measurements show the effect of decreasing temperature to be an increase in the incorporation of InN, accompanied by a small but discernible decrease in the ratio of GaN to AlN mole fractions. The incorporation of In is also shown to be significantly increased by decreasing the Al mole fraction. Optical emission peaks, observed by cathodoluminescence mapping and by photoluminescence, provide further information on the epilayer compositions as a function of substrate temperature, and the dependencies of peak energy and linewidth are plotted.

  14. InN nanorods prepared with CrN nanoislands by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Liu, Kuang-Wei; Chang, Shoou-Jinn; Young, Sheng-Joue; Hsueh, Tao-Hung; Hung, Hung; Mai, Yu-Chun; Wang, Shih-Ming; Chen, Kuan-Jen; Wu, Ya-Ling; Chen, Yue-Zhang

    2011-07-01

    The authors report the influence of CrN nanoisland inserted on growth of baseball-bat InN nanorods by plasma-assisted molecular beam epitaxy under In-rich conditions. By inserting CrN nanoislands between AlN nucleation layer and the Si (111) substrate, it was found that we could reduce strain form Si by inserting CrN nanoisland, FWHM of the x-ray rocking curve measured from InN nanorods from 3,299 reduced to 2,115 arcsec. It is due to the larger strain from lattice miss-match of the film-like InN structure; however, the strain from lattice miss-match was obvious reduced owing to CrN nanoisland inserted. The TEM images confirmed the CrN structures and In droplets dissociation from InN, by these results, we can speculate the growth mechanism of baseball-bat-like InN nanorods.

  15. Optical properties and structural characteristics of ZnMgO grown by plasma assisted molecular beam epitaxy

    SciTech Connect

    Wassner, Thomas A.; Laumer, Bernhard; Maier, Stefan; Stutzmann, Martin; Laufer, Andreas; Meyer, Bruno K.; Eickhoff, Martin

    2009-01-15

    Wurtzite Zn{sub 1-x}Mg{sub x}O thin films with Mg contents between x=0 and x=0.37 were grown on c-plane sapphire substrates by plasma assisted molecular beam epitaxy using a MgO/ZnMgO buffer layer. The a-lattice parameter is independent from the Mg concentration, whereas the c-lattice parameter decreases from 5.20 A for x=0 to 5.17 A for x=0.37, indicating pseudomorphic growth. The near band edge photoluminescence shows a blueshift with increasing Mg concentration to an emission energy of 4.11 eV for x=0.37. Simultaneously, the energetic position of the deep defect luminescence shows a linear shift from 2.2 to 2.8 eV. Low temperature transmission measurements reveal strong excitonic features for the investigated composition range and alloy broadening effects for higher Mg contents. The Stokes shift as well as the Urbach energy is increased to values of up to 125 and 54 meV for x=0.37, respectively, indicating exciton localization due to alloy fluctuations.

  16. Direct growth of hexagonal boron nitride/graphene heterostructures on cobalt foil substrates by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Xu, Zhongguang; Khanaki, Alireza; Tian, Hao; Zheng, Renjing; Suja, Mohammad; Liu, Jianlin; Zheng, Jian-Guo

    2016-07-25

    Graphene/hexagonal boron nitride (G/h-BN) heterostructures have attracted a great deal of attention because of their exceptional properties and wide variety of potential applications in nanoelectronics. However, direct growth of large-area, high-quality, and stacked structures in a controllable and scalable way remains challenging. In this work, we demonstrate the synthesis of h-BN/graphene (h-BN/G) heterostructures on cobalt (Co) foil by sequential deposition of graphene and h-BN layers using plasma-assisted molecular beam epitaxy. It is found that the coverage of h-BN layers can be readily controlled on the epitaxial graphene by growth time. Large-area, uniform-quality, and multi-layer h-BN films on thin graphite layers were achieved. Based on an h-BN (5–6 nm)/G (26–27 nm) heterostructure, capacitor devices with Co(foil)/G/h-BN/Co(contact) configuration were fabricated to evaluate the dielectric properties of h-BN. The measured breakdown electric field showed a high value of ∼2.5–3.2 MV/cm. Both I-V and C-V characteristics indicate that the epitaxial h-BN film has good insulating characteristics.

  17. Direct growth of hexagonal boron nitride/graphene heterostructures on cobalt foil substrates by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Xu, Zhongguang; Khanaki, Alireza; Tian, Hao; Zheng, Renjing; Suja, Mohammad; Zheng, Jian-Guo; Liu, Jianlin

    2016-07-01

    Graphene/hexagonal boron nitride (G/h-BN) heterostructures have attracted a great deal of attention because of their exceptional properties and wide variety of potential applications in nanoelectronics. However, direct growth of large-area, high-quality, and stacked structures in a controllable and scalable way remains challenging. In this work, we demonstrate the synthesis of h-BN/graphene (h-BN/G) heterostructures on cobalt (Co) foil by sequential deposition of graphene and h-BN layers using plasma-assisted molecular beam epitaxy. It is found that the coverage of h-BN layers can be readily controlled on the epitaxial graphene by growth time. Large-area, uniform-quality, and multi-layer h-BN films on thin graphite layers were achieved. Based on an h-BN (5-6 nm)/G (26-27 nm) heterostructure, capacitor devices with Co(foil)/G/h-BN/Co(contact) configuration were fabricated to evaluate the dielectric properties of h-BN. The measured breakdown electric field showed a high value of ˜2.5-3.2 MV/cm. Both I-V and C-V characteristics indicate that the epitaxial h-BN film has good insulating characteristics.

  18. Reducing quantum-memory-assisted entropic uncertainty by weak measurement and weak measurement reversal

    NASA Astrophysics Data System (ADS)

    Zhang, Yanliang; Fang, Maofa; Kang, Guodong; Zhou, Qingping

    2015-08-01

    We have investigated the dynamic features of the quantum-memory-assisted entropic uncertainty relation (QMA EUR) in the amplitude damping (AD) channel. The initial state of qubit system and quantum memory system shared between Alice and Bob is assumed as extended by Werner-like (EWL) state. To reduce the amount of entropic uncertainty of Pauli observables in this noisy channel, we presented a reduction scheme by means of weak measurements (WMs) and weak measurement reversals (WMRs) before and after the entangled system subjecting to the noisy channel. It is shown that the prior WM and poster WMR can effectively reduce quantity of entropic uncertainty, but the poster WM operation cannot played a positive role on reduction of quantity of entropic uncertainty. We hope that our proposal could be verified experimentally and might possibly have future applications in quantum information processing.

  19. Operational characteristics and plasma measurements in cylindrical Hall thrusters

    NASA Astrophysics Data System (ADS)

    Shirasaki, Atsushi; Tahara, Hirokazu

    2007-04-01

    The cylindrical Hall thruster (CHT) is an attractive approach to achieve a long lifetime thruster operation especially in low power space applications. Because of the larger volume-to-surface ratio than conventional coaxial Hall thrusters, the cylindrical Hall thrusters are characterized by a reduced heating of the thruster parts and potential lower erosion. Existing CHTs can feature a short coaxial channel in order to sustain a high ionization in the thruster discharge. A 5.6 cm diameter cylindrical Hall thruster was developed and operated with and without a short coaxial region of the thruster channel, in the power range of 70-300 W. It is shown that the CHT without coaxial region can operate stable and achieve higher thrust efficiency, 22%-32% more than that with a coaxial region. Plasma probe measurements inside the thruster channel and ion energy measurements in the plasma plume suggest that the ionization/acceleration region in the CHT is located near the anode region where a radial magnetic field is stronger.

  20. Particle and heat flux measurements in PDX edge plasmas

    SciTech Connect

    Budny, R.; Manos, D.

    1983-12-01

    This paper describes the use of novel combined Langmuir-calorimeter probes to measure edge plasma conditions near the midplane in PDX. The probes consisted of up to five Langmuir probes and up to two calorimeters. Single and double probe characteristics yield n/sub e/ and T/sub e/ which are compared with that derived from a triple probe analysis. The calorimeters measure heat flux in the electron and ion drift directions. This paper presents time-resolved radial profiles of n/sub e/, T/sub e/, V/sub F/ (floating potential), and P (heat flux) during high power neutral beam-heated, single-null discharges and circular scoop limiter discharges. The temporal dependence of these quantities displays the previous observed behavior with respect to gross discharge characteristics; however, an additional dependence on confinement mode has been observed. During the H-mode of energy confinement, a transient depression of n/sub e/, T/sub e/, and P occurs in the scrape-off plasma.

  1. E × B probe measurements in molecular and electronegative plasmas.

    PubMed

    Renaud, D; Gerst, D; Mazouffre, S; Aanesland, A

    2015-12-01

    This paper reports on the design, the building, the calibration, and the use of a compact E × B probe that acts as a velocity filter or a mass filter for ion species. A series of measurements has been performed in the discharge and in the beam of the PEGASES (Plasma Propulsion with Electronegative GASES) ion source. PEGASES is a unique inductively coupled radio-frequency source able to generate a beam of positive and negative ions when operated with an electronegative gas. In this study, experiments have been carried out with SF6. Calibrated E × B probe spectra indicate that the diagnostic tool can be used to determine the ion velocity and the plasma composition even when many molecular fragments are present. In addition, the probe is able to detect both positive and negative ions. Measurements show a large variety of positively charged ions coming from SF6. Conversely, the beam is solely composed of F(-) and SF6(-) negative ions in compliance with computer simulations.

  2. E × B probe measurements in molecular and electronegative plasmas

    NASA Astrophysics Data System (ADS)

    Renaud, D.; Gerst, D.; Mazouffre, S.; Aanesland, A.

    2015-12-01

    This paper reports on the design, the building, the calibration, and the use of a compact E × B probe that acts as a velocity filter or a mass filter for ion species. A series of measurements has been performed in the discharge and in the beam of the PEGASES (Plasma Propulsion with Electronegative GASES) ion source. PEGASES is a unique inductively coupled radio-frequency source able to generate a beam of positive and negative ions when operated with an electronegative gas. In this study, experiments have been carried out with SF6. Calibrated E × B probe spectra indicate that the diagnostic tool can be used to determine the ion velocity and the plasma composition even when many molecular fragments are present. In addition, the probe is able to detect both positive and negative ions. Measurements show a large variety of positively charged ions coming from SF6. Conversely, the beam is solely composed of F- and SF 6- negative ions in compliance with computer simulations.

  3. Measurements of Plasma Expansion due to Background Gas in the Electron Diffusion Gauge Experiment

    SciTech Connect

    Kyle A. Morrison; Stephen F. Paul; Ronald C. Davidson

    2003-08-11

    The expansion of pure electron plasmas due to collisions with background neutral gas atoms in the Electron Diffusion Gauge (EDG) experiment device is observed. Measurements of plasma expansion with the new, phosphor-screen density diagnostic suggest that the expansion rates measured previously were observed during the plasma's relaxation to quasi-thermal-equilibrium, making it even more remarkable that they scale classically with pressure. Measurements of the on-axis, parallel plasma temperature evolution support the conclusion.

  4. Flow measurements in the edge plasma of Tore Supra

    NASA Astrophysics Data System (ADS)

    Boucher, C.; Thibault, L.-G.; Gunn, J. P.; Pascal, J.-Y.; Devynck, P.; Tore Supra Team

    2001-03-01

    In recent years, the measurement of flow velocity of the plasma in the edge of tokamaks has gained in importance. The determination of this parameter is often done using electrostatic probe systems such as Mach probes or Gundestrup probes. A Gundestrup system was recently commissioned in Tore Supra. The perpendicular ( U⊥) and parallel ( U//) components of the velocity are determined from the six ion saturation currents using a neural network. The neural network was trained using ion saturation currents obtained from a two-dimensional kinetic code developed at Tore Supra. We will describe the Gundestrup probe and the neural network training, validation and implementation. Preliminary measurements in ergodic divertor discharges show U// and U⊥ profiles that exhibit small-scale spatial modulations similar to those reported for the temperature profiles.

  5. Kr II laser-induced fluorescence for measuring plasma acceleration

    SciTech Connect

    Hargus, W. A. Jr.

    2012-10-15

    We present the application of laser-induced fluorescence of singly ionized krypton as a diagnostic technique for quantifying the electrostatic acceleration within the discharge of a laboratory cross-field plasma accelerator also known as a Hall effect thruster, which has heritage as spacecraft propulsion. The 728.98 nm Kr II transition from the metastable 5d{sup 4}D{sub 7/2} to the 5p{sup 4}P{sub 5/2}{sup Ring-Operator} state was used for the measurement of laser-induced fluorescence within the plasma discharge. From these measurements, it is possible to measure velocity as krypton ions are accelerated from near rest to approximately 21 km/s (190 eV). Ion temperature and the ion velocity distributions may also be extracted from the fluorescence data since available hyperfine splitting data allow for the Kr II 5d{sup 4}D{sub 7/2}-5p{sup 4}P{sub 5/2}{sup Ring-Operator} transition lineshape to be modeled. From the analysis, the fluorescence lineshape appears to be a reasonable estimate for the relatively broad ion velocity distributions. However, due to an apparent overlap of the ion creation and acceleration regions within the discharge, the distributed velocity distributions increase ion temperature determination uncertainty significantly. Using the most probable ion velocity as a representative, or characteristic, measure of the ion acceleration, overall propellant energy deposition, and effective electric fields may be calculated. With this diagnostic technique, it is possible to nonintrusively characterize the ion acceleration both within the discharge and in the plume.

  6. Internal quantum efficiency of III-nitride quantum dot superlattices grown by plasma-assisted molecular-beam epitaxy

    SciTech Connect

    Gacevic, Z.; Kehagias, Th.; Koukoula, T.; Komninou, Ph.

    2011-05-15

    We present a study of the optical properties of GaN/AlN and InGaN/GaN quantum dot (QD) superlattices grown via plasma-assisted molecular-beam epitaxy, as compared to their quantum well (QW) counterparts. The three-dimensional/two-dimensional nature of the structures has been verified using atomic force microscopy and transmission electron microscopy. The QD superlattices present higher internal quantum efficiency as compared to the respective QWs as a result of the three-dimensional carrier localization in the islands. In the QW samples, photoluminescence (PL) measurements point out a certain degree of carrier localization due to structural defects or thickness fluctuations, which is more pronounced in InGaN/GaN QWs due to alloy inhomogeneity. In the case of the QD stacks, carrier localization on potential fluctuations with a spatial extension smaller than the QD size is observed only for the InGaN QD-sample with the highest In content (peak emission around 2.76 eV). These results confirm the efficiency of the QD three-dimensional confinement in circumventing the potential fluctuations related to structural defects or alloy inhomogeneity. PL excitation measurements demonstrate efficient carrier transfer from the wetting layer to the QDs in the GaN/AlN system, even for low QD densities ({approx}10{sup 10} cm{sup -3}). In the case of InGaN/GaN QDs, transport losses in the GaN barriers cannot be discarded, but an upper limit to these losses of 15% is deduced from PL measurements as a function of the excitation wavelength.

  7. STS-3/OSS-1 Plasma Diagnostics Package (PDP) measurements of the temperature pressure and plasma

    NASA Technical Reports Server (NTRS)

    Shawhan, S. D.; Murphy, G.

    1983-01-01

    Designed to withstand the thermal extremes of the STS-3 mission through the use of heaters and thermal blankets, the plasma diagnostics package sat on the release/engagement mechanism on the OSS-1 payload pallet without a coldplate and was attached to the RMS for two extended periods. Plots show temperature versus mission elapsed time for two temperature sensors. Pressure in the range of 10 to the -3 power torr and 10 to the -7 power torr, measured 3 inches from the skin of the package is plotted against GMT during the mission. The most distinctive feature of the pressure profile is the modulation at the obit period. It was found that pressure peaks when the atmospheric gas is rammed into the cargo bay. Electric and magnetic noise spectra and time variability due to orbiter systems, UHF and S-band transmitter field strengths, and measurements of the ion spectra obtained both in the cargo bay and during experiments are plotted.

  8. Formation of Apatite Coatings on an Artificial Ligament Using a Plasma- and Precursor-Assisted Biomimetic Process

    PubMed Central

    Mutsuzaki, Hirotaka; Yokoyama, Yoshiro; Ito, Atsuo; Oyane, Ayako

    2013-01-01

    A plasma- and precursor-assisted biomimetic process utilizing plasma and alternate dipping treatments was applied to a Leed-Keio artificial ligament to produce a thin coating of apatite in a supersaturated calcium phosphate solution. Following plasma surface modification, the specimen was alternately dipped in calcium and phosphate ion solutions three times (alternate dipping treatment) to create a precoating containing amorphous calcium phosphate (ACP) which is an apatite precursor. To grow an apatite layer on the ACP precoating, the ACP-precoated specimen was immersed for 24 h in a simulated body fluid with ion concentrations approximately equal to those in human blood plasma. The plasma surface modification was necessary to create an adequate apatite coating and to improve the coating adhesion depending on the plasma power density. The apatite coating prepared using the optimized conditions formed a thin-film that covered the entire surface of the artificial ligament. The resulting apatite-coated artificial ligament should exhibit improved osseointegration within the bone tunnel and possesses great potential for use in ligament reconstructions. PMID:24048251

  9. Interplanetary plasma scintillation parameters measurements retrieved from the spacecraft observations.

    NASA Astrophysics Data System (ADS)

    Molera Calvés, Guifré; Pogrebenko, S. V.; Wagner, J.; Maccaferri, G.; Colucci, G.; Kronschnabl, G.; Scilliro, F.; Bianco, G.; Pérez Ayúcar, M.; Cosmovici, C. B.

    2010-05-01

    Measurement of the Interplanetary Scintillations (IPS) of radio signals propagating through the plasma in the Solar System by the radio astronomical instruments is a powerful tool to characterise and study the spatial and temporal variation of the electron density in the Solar wind. Several techniques based on the observation of natural and artificial radio sources have been developed during the last 50 years. Here we report our results of the IPS parameters measurement based on the multi-station observations of the planetary mission spacecraft. The ESA Venus Express spacecraft was observed at X-band (8.4 GHz) by several European VLBI stations - Metsähovi Radio Observatory (Aalto University , FI), Medicina (INAF-RA, IT), Matera (ASI, IT), Wettzell (BKG, DE), Noto (INAF-IRA, IT) and Yebes (OAN-IGN, ES) during a 2008-2010 campaign in a framework of the PRIDE (Planetary Radio Interferometry and Doppler Experiments) project as a preparatory stage for the European Radio Astronomy VLBI facilities participation in the planned ESA planetary missions (EJSM, TESM, EVE and others). Observational data were processed at Metsähovi Radio Observatory with the on-purpose developed high performance, ultra-high spectral resolution and spacecraft tracking capable software spectrometer-correlator and analysed at the Joint Institute for VLBI in Europe (JIVE, NL). High quality of acquired and analysed data enables us to study and define several parameters of the S/C signal and accompanying "ranging" tones with milli-Hz accuracy, among which the phase fluctuations of the spacecraft signal carrier line can be used to characterise the interplanetary plasma density fluctuations along the signal propagation line at different spatial and temporal scales at different Solar elongations and which exhibits a near-Kolmogorov spectrum. Such essential parameters as the phase scintillation index and bandwidth of scintillations and their dependence on the solar elongation, distance to the target

  10. Oxygen-plasma-assisted molecular beam epitaxial growth of the stable oxides of iron

    SciTech Connect

    Chambers, S.A.; Gao, Y.; Kim, Y.J.

    1997-12-31

    The need to synthesize well-defined, single-crystal surfaces of model minerals is becoming increasingly more critical as the surface science of these materials matures. Magnetite (Fe{sub 3}O{sub 4}) and {alpha}- and {gamma}-hematite (Fe{sub 2}O{sub 3}) are important surfaces for fundamental studies in molecular geochemistry. We have used oxygen-plasma-assisted molecular beam epitaxy (MBE) to synthesize pure, crystallographically well-defined surfaces of these three materials. {alpha}-Fe{sub 2}O{sub 3} has been grown on {alpha}Al{sub 2}O{sub 3} r- c-, and a-plane, and Fe{sub 3}O{sub 4} and {gamma}-Fe{sub 2}O{sub 3} were grown on MgO(100), MgO(110), and {alpha}-Al{sub 2}O{sub 3}(0001). The resulting surfaces, along with their interfaces to small molecules, have been studied by a number of techniques. In general, we find that lattice matching, minimization of film/substrate interface chemistry, matching of surface free energies, oxygen sublattice continuity across the interface, and careful flux control during growth are extremely important for successful epitaxy. High-quality Fe{sub 2}O{sub 3} growth requires oxygen-rich conditions whereas more iron-rich conditions are required for the growth of high-quality Fe{sub 3}O{sub 4}. In this talk, we discuss recent progress in our laboratory in the growth and detailed characterization of these important oxide surfaces and interfaces.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  12. The use of microwave plasma-assisted CVD on nanostructured iron catalysts to grow isolated bundles of carbon nanotubes.

    PubMed

    Assouar, M B; Dossot, M; Rizk, S; Tiusan, C; Bougdira, J

    2010-02-10

    Catalysts play a key role in the growth of carbon nanotubes. The microwave plasma-assisted chemical vapor deposition (MPACVD) method is now commonly used for directional and conformal growth of carbon nanotubes (CNTs) on substrates. In this work, we report on the effect of H(2) plasma pre-treatment on the diameter and density of iron catalyst nanoparticles for different iron layer thicknesses in order to grow isolated bundles of CNTs. Atomic force microscopy shows first that as plasma power density increases, iron nanoparticle diameters decrease, which is due to the increasing of gas dissociation giving more ion bombardment energy, and second that the diameter of nanoparticles decreases with the catalyst thickness. The growth of CNT was carried out under different CH(4) concentrations for different iron film thicknesses. Transmission electron microscopy and Raman spectroscopy show that the synthesized CNT were of good quality and had an outer diameter between 5 and 10 nm.

  13. Metal-Assisted Laser-Induced Gas Plasma for the Direct Analysis of Powder Using Pulse CO2 Laser

    NASA Astrophysics Data System (ADS)

    Khumaeni, A.; Lie, Z. S.; Kurniawan, K. H.; Kagawa, K.

    2017-01-01

    Analysis of powder samples available in small quantities has been carried out using metal-assisted gas plasma by utilizing a transversely excited atmospheric (TEA) CO2 laser. The powder was homogeneously mixed with Si grease, and the mixed powder was painted on a metal subtarget. When a TEA CO2 laser was directly focused on the metal subtarget at atmospheric pressure of He gas, a high-temperature He gas plasma was induced. It is assumed that the powder particles were vaporized to be effectively atomized and excited in the gas plasma region. This method has been employed in the rapid analyses of elements in organic and inorganic powder samples present in small quantities. Detection of trace elements of Cr and Pb has been successfully made by using the supplement powder and loam soil, respectively. The detection limits of Pb in loam soil were approximately 20 mg/kg.

  14. Measuring the equatorial plasma bubble drift velocities over Morroco

    NASA Astrophysics Data System (ADS)

    Lagheryeb, Amine; Benkhaldoun, Zouhair; Makela, Jonathan J.; Harding, Brian; Kaab, Mohamed; Lazrek, Mohamed; Fisher, Daniel J.; Duly, Timothy M.; Bounhir, Aziza; Daassou, Ahmed

    2015-08-01

    In this work, we present a method to measure the drift velocities of equatorial plasma bubbles (EPBs) in the low latitude ionosphere. To calculate the EPB drift velocity, we use 630.0-nm airglow images collected by the Portable Ionospheric Camera and Small Scale Observatory (PICASSO) system deployed at the Oukkaimden observatory in Morocco. To extract the drift velocity, the individual images were processed by first spatially registering the images using the star field. After this, the stars were removed from the images using a point suppression methodology, the images were projected into geographic coordinates assuming an airglow emission altitude of 250 km. Once the images were projected into geographic coordinates, the intensities of the airglow along a line of constant geomagnetic latitude (31°) are used to detect the presence of an EPB, which shows up as a depletion in airglow intensity. To calculate the EPB drift velocity, we divide the spatial lag between depletions found in two images (found by the application of correlation analysis) by the time difference between these two images. With multiple images, we will have several velocity values and consequently we can draw the EPB drift velocity curve. Future analysis will compare the estimates of the plasma drift velocity with the thermospheric neutral wind velocity estimated by a collocated Fabry-Perot interferometer (FPI) at the observatory.

  15. Collision Rate Measurements in Mildly Correlated Ion Plasmas.

    NASA Astrophysics Data System (ADS)

    Anderegg, F.; Dubin, D. H. E.; Driscoll, C. F.; O'Neil, T. M.

    2006-10-01

    In strongly magnetized single component plasmas, collisional equipartition of T| and T is strongly suppressed by an adiabatic invariant, but enhanced by correlation effects. In essence, equipartition occurs only due to rare close collisions, and correlated particle Coulomb-screening makes them somewhat more likely. We conduct experiments with 10^6 to 10^8 Mg^+ ions in a Penning-Malmberg trap at B = 3T. For density n = 10^6, laser cooling parallel to B gives T| = 0.1K and T= 1K, resulting in a correlation parameter γ= 3. When the cooling is halted, T| rises slowly (˜ 1K/sec) due to weak neutral collisions, then rises abruptly as the equipartition rate becomes large. The abrupt equipartition is sometimes observed to occur spontaneously, especially when the plasma is contaminated by multiple ion species. Alternately, we can trigger the equipartition with an applied local heat pulse, and measure the ``burn front'' propagation. Experimental results will be compared to theories of correlation-enhanced equipartition, including the effects of heat transport due to long-range collisions. D.H.E. Dubin, Phys. Rev. Lett. 94, 025002 (2005); M.J. Jensen et al., Phys. Rev. Lett. 94, 025001 (2005).

  16. An instrument to measure job satisfaction of certified nurse assistants.

    PubMed

    Castle, Nicholas G

    2010-11-01

    We first presented the steps taken to develop the nursing home certified nurse assistant job satisfaction questionnaire (NH-CNA-JSQ) and, second, the psychometric properties of this instrument. Certified nurse assistants (CNAs) from 22 nursing homes in Pennsylvania were mailed the NH-CNA-JSQ. Of the 726 surveys mailed, 479 usable surveys were returned, giving a 66% response rate. The factor analyses show that the items were representative of the underlying factors, representing seven subscales. The percentage of CNAs not providing responses for each question was low (1.5%), and the floor and ceiling effects of the responses for each of the 19 questions were low (i.e., 9.4% and 5.2%, respectively). The item-scale internal consistency analyses determined that the correlation of items within indexes was higher than those of items with other indexes. Cronbach's alpha values for the domains ranged from .72 to .83 and were all higher than the usually recommended levels. Criterion validity was high (.77) as was the index of content validity (p > .05). We believe that we have produced a short psychometrically sound job satisfaction instrument for use in nursing homes. Copyright © 2010 Elsevier Inc. All rights reserved.

  17. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions

    SciTech Connect

    Nad, Shreya; Gu, Yajun; Asmussen, Jes

    2015-07-15

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100–260 Torr pressure range and 1.5–2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (η{sub coup}) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  19. Measuring the plasma environment at Mercury: The fast imaging plasma spectrometer

    NASA Astrophysics Data System (ADS)

    Koehn, P. L.; Zurbuchen, T. H.; Gloeckler, G.; Lundgren, R. A.; Fisk, L. A.

    2002-09-01

    The plasma environment at Mercury is a rich laboratory for studying the interaction of the solar wind with a planet. Three primary populations of ions exist at Mercury: solar wind, magnetospheric and pickup ions. These pickup ions are generated through the ionization of Mercury's exosphere or are sputtered particles from the Mercury surface. A comprehensive mission to Mercury, such as MESSENGER, should include a sensor that is able to determine the dynamical properties and composition of all these plasma components. An instrument to measure the composition of these ion populations and their three dimensional velocity distribution functions must be lightweight, fast, and have a very large field of view. The Fast Imaging Plasma Spectrometer (FIPS) is an imaging mass spectrometer, part of NASA's MESSENGER mission, the first Mercury orbiter. This versatile instrument has a very small footprint, and has a mass that is about one order of magnitude less than other comparable systems. It maintains a nearly full-hemisphere field of view, suitable for either spinning or three-axis-stabilized platforms. The major piece of innovation to enable this sensor is a new deflection system geometry that enables a large instantaneous (~1.5() field of view. This novel electrostatic analyzer system is then combined with a position sensitive time-of-flight system. We discuss the design and prototype tests of the FIPS deflection system and show how this system is expected to address one key problem in Mercury science, that of the nature of the radar-bright regions at the Hermean poles.

  20. Redeposition in plasma-assisted atomic layer deposition: Silicon nitride film quality ruled by the gas residence time

    SciTech Connect

    Knoops, Harm C. M. E-mail: w.m.m.kessels@tue.nl; Peuter, K. de; Kessels, W. M. M. E-mail: w.m.m.kessels@tue.nl

    2015-07-06

    The requirements on the material properties and growth control of silicon nitride (SiN{sub x}) spacer films in transistors are becoming ever more stringent as scaling of transistor structures continues. One method to deposit high-quality films with excellent control is atomic layer deposition (ALD). However, depositing SiN{sub x} by ALD has turned out to be very challenging. In this work, it is shown that the plasma gas residence time τ is a key parameter for the deposition of SiN{sub x} by plasma-assisted ALD and that this parameter can be linked to a so-called “redeposition effect”. This previously ignored effect, which takes place during the plasma step, is the dissociation of reaction products in the plasma and the subsequent redeposition of reaction-product fragments on the surface. For SiN{sub x} ALD using SiH{sub 2}(NH{sup t}Bu){sub 2} as precursor and N{sub 2} plasma as reactant, the gas residence time τ was found to determine both SiN{sub x} film quality and the resulting growth per cycle. It is shown that redeposition can be minimized by using a short residence time resulting in high-quality films with a high wet-etch resistance (i.e., a wet-etch rate of 0.5 nm/min in buffered HF solution). Due to the fundamental nature of the redeposition effect, it is expected to play a role in many more plasma-assisted ALD processes.

  1. Comparative measurements of plasma potential with ball-pen and Langmuir probe in low-temperature magnetized plasma

    SciTech Connect

    Zanáška, M.; Kudrna, P.; Tichý, M.; Adámek, J.; Peterka, M.

    2015-03-15

    The ball-pen probe (BPP) is used for direct plasma potential measurements in magnetized plasma. The probe can adjust the ratio of the electron and ion saturation currents I{sub sat}{sup −}/I{sub sat}{sup +} to be close to one and therefore its I-V characteristic becomes nearly symmetric. If this is achieved, the floating potential of the BPP is close to the plasma potential. Because of its rather simple construction, it offers an attractive probe for measurements in magnetized plasma. Comparative measurements of plasma potential by BPPs of different dimensions as well as one Langmuir probe (LP) in an argon discharge plasma of a cylindrical magnetron were performed at various experimental conditions. An additional comparison by an emissive probe was also performed. All these types of probes provide similar values of plasma potential in a wide range of plasma parameters. Our results for three different BPP dimensions indicate that the BPP can be operated in a cylindrical magnetron DC argon discharge if the value of the ratio of the magnetic field and neutral gas pressure, B/p, is greater than approximately 10 mT/Pa.

  2. Plasma-assisted nitrogen doping of VACNTs for efficiently enhancing the supercapacitor performance

    NASA Astrophysics Data System (ADS)

    Mashayekhi, Alireza; Hosseini, Seyed Mahmoud; Hassanpour Amiri, Morteza; Namdar, Naser; Sanaee, Zeinab

    2016-06-01

    Nitrogen doping of vertically aligned carbon nanotubes (VACNTs) using plasma-enhanced chemical vapour deposition has been investigated to improve the supercapacitance performance of CNTs. Incorporating electrochemical measurements on the open-ended nitrogen-doped CNTs, showed the achievement of 6 times improvement in the capacitance value. For nitrogen-doped CNTs on silicon substrate, specific capacitance of 60 F g-1 was obtained in 0.5 M KCl solution, with capacity retention ratio above 90 % after cycled at 0.1 A g-1 for 5000 cycles. Using this sample, a symmetric supercapacitance was fabricated which showed the power density of 37.5 kW kg-1. The facile fabrication approach and its excellent capacitance improvement, propose it as an efficient technique for enhancing the supercapacitance performance of the carbon-based electrodes.

  3. Cold-plasma assisted grafting of cellulose fibres by acrylic monomers

    NASA Astrophysics Data System (ADS)

    Gaiolas, Carla; Amaral, Maria Emilia; Costa, Ana Paula; Santos Silva, Manuel José; Belgacem, Mohamed Naceur

    2012-07-01

    Additive-free hand sheet paper samples were activated by cold-plasma in the presence of acrylic acid (AAc), acrylamide (AAm), methyl acrylate (MAc) and methyl methacrylate (MMa). The characterisation of the modified substrates showed that there grafting has occurred efficiently, as established by weight gain and FTIR spectroscopy. The contact angle measurement were carried out, as a function of pH and showed that the deposition of a drop of water at the surface of the tested samples formed 55° for unmodified substrate to 87°, for MMa-treated papers, respectively, indicating that the surface has became totally hydrophobic. ATR-FTIR spectroscopy was used to check the grafting efficiency.

  4. Measurements of laser-induced plasma temperature field in deep penetration laser welding

    NASA Astrophysics Data System (ADS)

    Chen, Genyu; Zhang, Mingjun; Zhao, Zhi; Zhang, Yi; Li, Shichun

    2013-02-01

    Laser-induced plasma in deep penetration laser welding is located inside or outside the keyhole, namely, keyhole plasma or plasma plume, respectively. The emergence of laser-induced plasma in laser welding reveals important information of the welding technological process. Generally, electron temperature and electron density are two important characteristic parameters of plasma. In this paper, spectroscopic measurements of electron temperature and electron density of the keyhole plasma and plasma plume in deep penetration laser welding conditions were carried out. To receive spectra from several points separately and simultaneously, an Optical Multi-channel Analyser (OMA) was developed. On the assumption that the plasma was in local thermal equilibrium, the temperature was calculated with the spectral relative intensity method. The spectra collected were processed with Abel inversion method to obtain the temperature fields of keyhole plasma and plasma plume.

  5. Magnetic Field Measurements in Plasmas: Beyond the Traditional Zeeman Spectroscopy

    SciTech Connect

    Doron, R.; Stambulchik, E.; Tessarin, S.; Kroupp, E.; Citrin, J.; Maron, Y.; Tsigutkin, K.

    2009-09-10

    We discuss a new approach to measure magnetic fields in situations where the magnetic-field properties and/or the plasma regime make the traditional Zeeman spectroscopy inapplicable. The approach is particularly useful when the field direction and/or magnitude vary significantly in the region viewed or during the diagnostic system's integration time, and hence no Zeeman splitting can be observed. Similar difficulty may also occur for high-energy-density conditions, where the Zeeman pattern is often completely smeared, regardless of the field distribution, due to the dominant contributions of the Stark and Doppler broadenings to the spectral-line shapes. In the new approach, the magnetic field is inferred from the comparison of the line-shapes of different fine-structure components of the same multiplet, which practically have the same Stark and Doppler broadenings, but different magnetic-field-induced contributions. Limitations of the new method are discussed.

  6. Methodology of modeling and measuring computer architectures for plasma simulations

    NASA Technical Reports Server (NTRS)

    Wang, L. P. T.

    1977-01-01

    A brief introduction to plasma simulation using computers and the difficulties on currently available computers is given. Through the use of an analyzing and measuring methodology - SARA, the control flow and data flow of a particle simulation model REM2-1/2D are exemplified. After recursive refinements the total execution time may be greatly shortened and a fully parallel data flow can be obtained. From this data flow, a matched computer architecture or organization could be configured to achieve the computation bound of an application problem. A sequential type simulation model, an array/pipeline type simulation model, and a fully parallel simulation model of a code REM2-1/2D are proposed and analyzed. This methodology can be applied to other application problems which have implicitly parallel nature.

  7. Electric field and plasma density measurements in the auroral electrojet

    NASA Astrophysics Data System (ADS)

    Pfaff, R. F.; Kelley, M. C.; Fejer, B. G.; Kudeki, E.; Carlson, C. W.; Pedersen, A.; Hausler, B.

    1984-01-01

    Extensive experimental and theoretical studies of auroral and equatorial electrojet irregularities have been conducted for the last two decades. The present investigation is concerned with electric field and plasma density fluctuation measurements made on board of the Porcupine II sounding rocket and on a free-flyer ejected from the main spacecraft. The Porcupine II sounding rocket payload was launched at 1922:00 UT from Kiruna, Sweden, on March 20, 1977. The considered results show electrostatic turbulence in the unstable auroral E region confined to a layer between 96 and 121 km. The similarities between the observations of two simultaneous payloads spaced a few kilometers apart indicate that on a large scale, the electrojet turbulence displays uniform characteristics.

  8. Methodology of modeling and measuring computer architectures for plasma simulations

    NASA Technical Reports Server (NTRS)

    Wang, L. P. T.

    1977-01-01

    A brief introduction to plasma simulation using computers and the difficulties on currently available computers is given. Through the use of an analyzing and measuring methodology - SARA, the control flow and data flow of a particle simulation model REM2-1/2D are exemplified. After recursive refinements the total execution time may be greatly shortened and a fully parallel data flow can be obtained. From this data flow, a matched computer architecture or organization could be configured to achieve the computation bound of an application problem. A sequential type simulation model, an array/pipeline type simulation model, and a fully parallel simulation model of a code REM2-1/2D are proposed and analyzed. This methodology can be applied to other application problems which have implicitly parallel nature.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  10. Structural, Optical and Electrical Properties of n-type GaN on Si (111) Grown by RF-plasma assisted Molecular Beam Epitaxy

    SciTech Connect

    Chin, C. W.; Hassan, Z.; Yam, F. K.

    2008-05-20

    In this paper, we present the study of the structural, optical and electrical of n-type GaN grown on silicon (111) by RF plasma-assisted molecular beam epitaxy (RF-MBE). X-ray diffraction (XRD) measurement reveals that the GaN was epitaxially grown on silicon. For the photoluminescence (PL) measurement, a sharp and intense peak at 364.5 nm indicates that the sample is of high optical quality. Hall effect measurement shows that the film has a carrier concentration of 3.28x10{sup 19} cm{sup -3}. The surface of the n-type GaN was smooth and no any cracks and pits.

  11. Isometric hip and knee torque measurements as an outcome measure in robot assisted gait training.

    PubMed

    Galen, Sujay S; Clarke, Celia J; McLean, Alan N; Allan, David B; Conway, Bernard A

    2014-01-01

    Strength changes in lower limb muscles following robot assisted gait training (RAGT) in subjects with incomplete spinal cord injury (ISCI) has not been quantified using objective outcome measures. To record changes in the force generating capacity of lower limb muscles (recorded as peak voluntary isometric torque at the knee and hip), before, during and after RAGT in both acute and subacute/chronic ISCI subjects using a repeated measures study design. Eighteen subjects with ISCI participated in this study (Age range: 26-63 years mean age = 49.3 ± 11 years). Each subject participated in the study for a total period of eight weeks, including 6 weeks of RAGT using the Lokomat system (Hocoma AG, Switzerland). Peak torques were recorded in hip flexors, extensors, knee flexors and extensors using torque sensors that are incorporated within the Lokomat. All the tested lower limb muscle groups showed statistically significant (p < 0.001) increases in peak torques in the acute subjects. Comparison between the change in peak torque generated by a muscle and its motor score over time showed a non-linear relationship. The peak torque recorded during isometric contractions provided an objective outcome measure to record changes in muscle strength following RAGT.

  12. Towards higher stability of resonant absorption measurements in pulsed plasmas

    SciTech Connect

    Britun, Nikolay; Michiels, Matthieu; Snyders, Rony

    2015-12-15

    Possible ways to increase the reliability of time-resolved particle density measurements in pulsed gaseous discharges using resonant absorption spectroscopy are proposed. A special synchronization, called “dynamic source triggering,” between a gated detector and two pulsed discharges, one representing the discharge of interest and another being used as a reference source, is developed. An internal digital delay generator in the intensified charge coupled device camera, used at the same time as a detector, is utilized for this purpose. According to the proposed scheme, the light pulses from the reference source follow the gates of detector, passing through the discharge of interest only when necessary. This allows for the utilization of short-pulse plasmas as reference sources, which is critical for time-resolved absorption analysis of strongly emitting pulsed discharges. In addition to dynamic source triggering, the reliability of absorption measurements can be further increased using simultaneous detection of spectra relevant for absorption method, which is also demonstrated in this work. The proposed methods are illustrated by the time-resolved measurements of the metal atom density in a high-power impulse magnetron sputtering (HiPIMS) discharge, using either a hollow cathode lamp or another HiPIMS discharge as a pulsed reference source.

  13. Wavefront-sensor-based electron density measurements for laser-plasma accelerators

    SciTech Connect

    Plateau, Guillaume; Matlis, Nicholas; Geddes, Cameron; Gonsalves, Anthony; Shiraishi, Satomi; Lin, Chen; van Mourik, Reinier; Leemans, Wim

    2010-02-20

    Characterization of the electron density in laser produced plasmas is presented using direct wavefront analysis of a probe laser beam. The performance of a laser-driven plasma-wakefield accelerator depends on the plasma wavelength, hence on the electron density. Density measurements using a conventional folded-wave interferometer and using a commercial wavefront sensor are compared for different regimes of the laser-plasma accelerator. It is shown that direct wavefront measurements agree with interferometric measurements and, because of the robustness of the compact commercial device, have greater phase sensitivity, straightforward analysis, improving shot-to-shot plasma-density diagnostics.

  14. Rotation Rate of Saturn's Magnetosphere using CAPS Plasma Measurements

    NASA Technical Reports Server (NTRS)

    Sittler, E.; Cooper, J.; Simpson, D.; Paterson, W.

    2012-01-01

    We present the present status of an investigation of the rotation rate of Saturn 's magnetosphere using a 3D velocity moment technique being developed at Goddard which is similar to the 2D version used by Sittler et al. (2005) [1] for SOI and similar to that used by Thomsen et al. (2010). This technique allows one to nearly cover the full energy range of the CAPS IMS from 1 V less than or equal to E/Q less than 50 kV. Since our technique maps the observations into a local inertial frame, it does work during roll manoeuvres. We have made comparisons with Wilson et al. (2008) [2] (2005-358 and 2005-284) who performs a bi-Maxwellian fit to the ion singles data and our results are nearly identical. We will also make comparisons with results by Thomsen et al. (2010) [3]. Our analysis uses ion composition data to weight the non-compositional data, referred to as singles data, to separate H+, H2+ and water group ions (W+) from each other. The ion data set is especially valuable for measuring flow velocities for protons, which are more difficult to derive using singles data within the inner magnetosphere, where the signal is dominated by heavy ions (i.e., proton peak merges with W+ peak as low energy shoulder). Our technique uses a flux function, which is zero in the proper plasma flow frame, to estimate fluid parameter uncertainties. The comparisons investigate the experimental errors and potential for systematic errors in the analyses, including ours. The rolls provide the best data set when it comes to getting 4PI coverage of the plasma but are more susceptible to time aliasing effects. Since our analysis is a velocity moments technique it will work within the inner magnetosphere where pickup ions are important and velocity distributions are non-Maxwellian. So, we will present results inside Enceladus' L shell and determine if mass loading is important. In the future we plan to make comparisons with magnetic field observations, use Saturn ionosphere conductivities as

  15. On-line depth measurement for laser-drilled holes based on the intensity of plasma emission

    NASA Astrophysics Data System (ADS)

    Ho, Chao-Ching; Chiu, Chih-Mu; Chang, Yuan-Jen; Hsu, Jin-Chen; Kuo, Chia-Lung

    2014-09-01

    The direct time-resolved depth measurement of blind holes is extremely difficult due to the short time interval and the limited space inside the hole. This work presents a method that involves on-line plasma emission acquisition and analysis to obtain correlations between the machining processes and the optical signal output. Given that the depths of laser-machined holes can be estimated on-line using a coaxial photodiode, this was employed in our inspection system. Our experiments were conducted in air under normal atmospheric conditions without gas assist. The intensity of radiation emitted from the vaporized material was found to correlate with the depth of the hole. The results indicate that the estimated depths of the laser-drilled holes were inversely proportional to the maximum plasma light emission measured for a given laser pulse number.

  16. Control of ion content and nitrogen species using a mixed chemistry plasma for GaN grown at extremely high growth rates >9 μm/h by plasma-assisted molecular beam epitaxy

    SciTech Connect

    Gunning, Brendan P.; Clinton, Evan A.; Merola, Joseph J.; Doolittle, W. Alan; Bresnahan, Rich C.

    2015-10-21

    Utilizing a modified nitrogen plasma source, plasma assisted molecular beam epitaxy (PAMBE) has been used to achieve higher growth rates in GaN. A higher conductance aperture plate, combined with higher nitrogen flow and added pumping capacity, resulted in dramatically increased growth rates up to 8.4 μm/h using 34 sccm of N{sub 2} while still maintaining acceptably low operating pressure. It was further discovered that argon could be added to the plasma gas to enhance growth rates up to 9.8 μm/h, which was achieved using 20 sccm of N{sub 2} and 7.7 sccm Ar flows at 600 W radio frequency power, for which the standard deviation of thickness was just 2% over a full 2 in. diameter wafer. A remote Langmuir style probe employing the flux gauge was used to indirectly measure the relative ion content in the plasma. The use of argon dilution at low plasma pressures resulted in a dramatic reduction of the plasma ion current by more than half, while high plasma pressures suppressed ion content regardless of plasma gas chemistry. Moreover, different trends are apparent for the molecular and atomic nitrogen species generated by varying pressure and nitrogen composition in the plasma. Argon dilution resulted in nearly an order of magnitude achievable growth rate range from 1 μm/h to nearly 10 μm/h. Even for films grown at more than 6 μm/h, the surface morphology remained smooth showing clear atomic steps with root mean square roughness less than 1 nm. Due to the low vapor pressure of Si, Ge was explored as an alternative n-type dopant for high growth rate applications. Electron concentrations from 2.2 × 10{sup 16} to 3.8 × 10{sup 19} cm{sup −3} were achieved in GaN using Ge doping, and unintentionally doped GaN films exhibited low background electron concentrations of just 1–2 × 10{sup 15} cm{sup −3}. The highest growth rates resulted in macroscopic surface features due to Ga cell spitting, which is an engineering challenge still to be

  17. Thermophysical property measurement at high temperatures by laser-produced plasmas

    SciTech Connect

    Kim, Y.W.

    1993-05-01

    Excitation by a high-power laser pulse of a material surface generates a sequence of plasma, fluid flow, and acoustic events. These are well separated in time, and their detection and analysis can lead to determination of material properties of the condensed phase target. We have developed a new methodology for real-time determination of molten metal composition by time-resolved spectroscopy of laser-produced plasmas (LPP). If the laser pulse is shaped in such a way that the movement of the bulk surface due to evaporation is kept in pace with the thermal diffusion front advancing into the interior of the target, the LPP plume becomes representative of the bulk in elemental composition. In addition, the mass loss due to LPP ablation is very well correlated with the thermal diffusivity of the target matter. For several elemental solid specimens, we show that the product of the ablation thickness and heat of formation is proportional to the thermal diffusivity per unit molecular weight. Such measurements can be extended to molten metal specimens if the mass loss by ablation, density, heat of formation, and molecular weight can be determined simultaneously. The results from the solid specimen and the progress with a levitation-assisted molten metal experiment are presented.

  18. Computer assisted measurement of femoral cortex thickening on radiographs

    NASA Astrophysics Data System (ADS)

    Yao, Jianhua; Liu, Yixun; Chen, Foster; Summers, Ronald M.; Bhattacharyya, Timothy

    2013-03-01

    Radiographic features such as femoral cortex thickening have been frequently observed with atypical subtrochanteric fractures. These features may be a valuable finding to help prevent fractures before they happen. The current practice of manual measurement is often subjective and inconsistent. We developed a semi-automatic tool to consistently measure and monitor the progress of femoral cortex thickening on radiographs. By placing two seed points on each side of the femur, the program automatically extracts the periosteal and endosteal layers of the cortical shell by active contour models and B-spline fitting. Several measurements are taken along the femur shaft, including shaft diameter, cortical thickness, and integral area for medial and lateral cortex. The experiment was conducted on 52 patient datasets. The semi-automatic measurements were validated against manual measurements on 52 patients and demonstrated great improvement in consistency and accuracy (p<0.001).

  19. Robot-Assisted Measurements in Data Sparse Regions

    NASA Astrophysics Data System (ADS)

    Peschel, J.; Young, S. N.; Penny, G.; Thompson, S. E.; Srinivasan, V.

    2015-12-01

    This work presents a methodology for topographic and bathymetric data collection using multiple robot platforms in the data sparse Arkavathy region around Bangalore, India. In the late 20th century, Arkavathy River flows began declining; consequently, a dependence on the Cauvery River has occurred while the reasons for the drying of the Arkavathy remain unknown. Understanding this shift is critical for managing local water resources, specifically for quantifying the socio-hydrologic effects of human intervention through the use of tanks which serve as a controlled method of irrigation for farmers. Determining the potential volume of water capable of being stored in these tanks can aid investigators to better understand hydrologic parameters such as recharge and streamflow. At present, satellite and LiDAR data are the two methods to collect topographic and bathymetric data for this region, but both options are either too poor of resolution or too costly. Small unmanned aerial vehicles (UAVs) and unmanned surface vehicles (USVs) were demonstrated as low-cost and reliable, high-resolution alternatives for surface data gathering at two locations in the Arkavathy basin during a Summer 2015 field campaign: i) Hadonahalli, and ii) SM Gollahalli. This robot-assisted approach for data gathering will be of interest to investigators in the geophysical sciences, especially those operating with budget constraints in data sparse regions.

  20. Fast fabrication of nano-structured anti-reflection layers for enhancement of solar cells performance using plasma sputtering and infrared assisted roller embossing techniques.

    PubMed

    Liu, Shih-Jung; Liao, Che-Ting

    2012-02-27

    This paper reports the continuous fabrication of dual-side nano-structured anti-reflection protective layer for performance enhancement of solar cells using plasma sputtering and infrared assisted roller embossing techniques. Nano-structures were first deposited onto the surface of glass substrates using the plasma sputtering technique. After electroforming, a nickel master mold containing nano-array of 30 nm was obtained. The mold was then attached to the surfaces of the two metallic rollers in an infrared assisted roll-to-roll embossing facility. The embossing facility was used to replicate the nano-structures onto 60 μm thick polyethylene terephthalate (PET) films in the experiments. The embossed films were characterized using UV-vis spectrophotometer, atomic force microscope (AFM), and scanning electron microscope (SEM); its total conversion efficiency for solar cells was also measured by a solar simulator. The experimental results showed that the fabricated films could effectively reduce the reflectance and increase the conversion efficiency of solar cells. The proposed method shows great potential for fast fabrication of the anti-reflection protective layer of solar cells due to its simplicity and versatility.