Sample records for xenon gas mixture

  1. Radiation properties of low-pressure discharges in rare-gas mixtures containing xenon

    NASA Astrophysics Data System (ADS)

    Gortchakov, S.; Uhrlandt, D.

    2005-02-01

    Glow discharges in mixtures of xenon with other rare gases can be used as alternatives to mercury-containing UV/VUV radiation sources and fluorescent lamps. The advantages of such sources are environmental compatibility, instant light output after switching on, and less pronounced temperature dependence. However, the optimum choice of the gas composition with respect to the maximum efficiency and power of the xenon resonance radiation as well as to a stable discharge operation still remains an open question. The dc cylindrical positive column of low-pressure discharges in rare-gas mixtures is studied by a detailed self-consistent kinetic description. The influence of the buffer gases helium, neon and argon as well as the appropriate choice of the xenon admixture are revealed by analysing different triple-gas mixtures. Changes in the global power budget and the radial structure of the plasma are discussed. A mixture of He and about 1-2% Xe arises as an optimum composition.

  2. A Method for Calculating Viscosity and Thermal Conductivity of a Helium-Xenon Gas Mixture

    NASA Technical Reports Server (NTRS)

    Johnson, Paul K.

    2006-01-01

    A method for calculating viscosity and thermal conductivity of a helium-xenon (He-Xe) gas mixture was employed, and results were compared to AiResearch (part of Honeywell) analytical data. The method of choice was that presented by Hirschfelder with Singh's third-order correction factor applied to thermal conductivity. Values for viscosity and thermal conductivity were calculated over a temperature range of 400 to 1200 K for He-Xe gas mixture molecular weights of 20.183, 39.94, and 83.8 kg/kmol. First-order values for both transport properties were in good agreement with AiResearch analytical data. Third-order-corrected thermal conductivity values were all greater than AiResearch data, but were considered to be a better approximation of thermal conductivity because higher-order effects of mass and temperature were taken into consideration. Viscosity, conductivity, and Prandtl number were then compared to experimental data presented by Taylor.

  3. Ethane-xenon mixtures under shock conditions

    NASA Astrophysics Data System (ADS)

    Magyar, Rudolph J.; Root, Seth; Cochrane, Kyle; Mattsson, Thomas R.; Flicker, Dawn G.

    2015-04-01

    Mixtures of light elements with heavy elements are important in inertial confinement fusion. We explore the physics of molecular scale mixing through a validation study of equation of state (EOS) properties. Density functional theory molecular dynamics (DFT-MD) at elevated temperature and pressure is used to obtain the thermodynamic state properties of pure xenon, ethane, and various compressed mixture compositions along their principal Hugoniots. To validate these simulations, we have performed shock compression experiments using the Sandia Z-Machine. A bond tracking analysis correlates the sharp rise in the Hugoniot curve with the completion of dissociation in ethane. The DFT-based simulation results compare well with the experimental data along the principal Hugoniots and are used to provide insight into the dissociation and temperature along the Hugoniots as a function of mixture composition. Interestingly, we find that the compression ratio for complete dissociation is similar for several compositions suggesting a limiting compression for C-C bonded systems.

  4. Monte Carlo simulation study of the Fano factor, w value, and energy resolution for the absorption of soft x rays in xenon{endash}neon gas mixtures

    SciTech Connect

    Santos, F. P.; Dias, T. H. V. T.; Rachinhas, P. J. B. M.; Conde, C. A. N.; Stauffer, A. D.

    2001-06-15

    Xenon gas proportional-scintillation counters (GPSC) have many applications in the detection of soft x rays where their energy resolution, R, is comparable to solid-state detectors when large window areas are required. However, R is known to deteriorate for energies E{sub xr} below 2{endash}3 keV due to electron loss to the entrance window. Since the addition of a lighter noble gas increases the absorption depth, we have investigated the use of Xe{endash}Ne gas mixtures at atmospheric pressure as detector fillings. The results of a Monte Carlo simulation study of the Fano factor, F, the w value, and the intrinsic energy resolution, R=2.36(Fw/E{sub xr}){sup 1/2}, are presented for Xe{endash}Ne mixtures and pure Xe and Ne. The results show that the addition of Ne to Xe reduces the intrinsic energy resolution R but this never compensates for the reduction in scintillation yield in GPSC applications, implying that the instrumental energy resolution R will only improve with the addition of Ne when electron loss to the window in pure Xe is significant. The simulation reproduces the photoionization process of the Xe and Ne atoms, the vacancy cascade decay of the residual ions, and the elastic and inelastic scattering of electrons by the gas atoms. The contribution of energy and charge transfer mechanisms such as Penning, associative, and transfer ionization is discussed in detail. It is shown that Penning and associative ionization are the crucial indirect ionization processes which determine the behavior of F and w at low concentrations of Xe. The importance of the nonmetastable Ne states is also assessed. {copyright} 2001 American Institute of Physics.

  5. Purification of krypton-xenon mixture from fluorine-containing gases

    NASA Astrophysics Data System (ADS)

    Adamov, V. S.; Yatkin, V. A.

    2007-06-01

    Active alumina was used to purify krypton-xenon mixtures from fluorine-containing gases (tetrafluoromethane and sulfur hexafluoride). At 580°C, the admixtures are converted into aluminum trifluoride, with their content in the test gas mixture reducing from hundreds of ppm to 0.1 ppm or even below.

  6. TOF electron drift measurements in xenon difluoride (XeF2) and hydrogen sulfide (H2S) gas mixtures

    Microsoft Academic Search

    C. A. Denman; L. A. Schlie

    1989-01-01

    Sensitive, high-temporal-resolution, time-of-flight (TOF) drift measurements yielding the drift velocity, longitudinal diffusion, and a new, higher order diffusion coefficient have been obtained in the gases XeF2 and H2S. These gases are of interest because of their potential as lasing constituents when combined with the highly energetic (8.5 MJ\\/kg) hydrogen azide (HN3) gas. Kinetic studies indicate that a hybrid electrochemical laser

  7. Hyperpolarized xenon NMR and MRI signal amplification by gas extraction

    PubMed Central

    Zhou, Xin; Graziani, Dominic; Pines, Alexander

    2009-01-01

    A method is reported for enhancing the sensitivity of NMR of dissolved xenon by detecting the signal after extraction to the gas phase. We demonstrate hyperpolarized xenon signal amplification by gas extraction (Hyper-SAGE) in both NMR spectra and magnetic resonance images with time-of-flight information. Hyper-SAGE takes advantage of a change in physical phase to increase the density of polarized gas in the detection coil. At equilibrium, the concentration of gas-phase xenon is ?10 times higher than that of the dissolved-phase gas. After extraction the xenon density can be further increased by several orders of magnitude by compression and/or liquefaction. Additionally, being a remote detection technique, the Hyper-SAGE effect is further enhanced in situations where the sample of interest would occupy only a small proportion of the traditional NMR receiver. Coupled with targeted xenon biosensors, Hyper-SAGE offers another path to highly sensitive molecular imaging of specific cell markers by detection of exhaled xenon gas. PMID:19805177

  8. Applications of controlled-flow laser-polarized xenon gas to porous and granular media study

    E-print Network

    R. W. Mair; R. Wang; M. S. Rosen; D. Candela; D. G. Cory; R. L. Walsworth

    2002-11-09

    We report initial NMR studies of continuous flow laser-polarized xenon gas, both in unrestricted tubing, and in a model porous media. The study uses Pulsed Gradient Spin Echo-based techniques in the gas-phase, with the aim of obtaining more sophisticated information than just translational self-diffusion coefficients. Pulsed Gradient Echo studies of continuous flow laser-polarized xenon gas in unrestricted tubing indicate clear diffraction minima resulting from a wide distribution of velocities in the flow field. The maximum velocity experienced in the flow can be calculated from this minimum, and is seen to agree with the information from the complete velocity spectrum, or motion propagator, as well as previously published images. The susceptibility of gas flows to parameters such as gas mixture content, and hence viscosity, are observed in experiments aimed at identifying clear structural features from echo attenuation plots of gas flow in porous media. Gas-phase NMR scattering, or position correlation flow-diffraction, previously clearly seen in the echo attenuation data from laser-polarized xenon flowing through a 2 mm glass bead pack is not so clear in experiments using a different gas mixture. A propagator analysis shows most gas in the sample remains close to static, while a small portion moves through a presumably near-unimpeded path at high velocities.

  9. Virial equation of state of helium, xenon, and helium-xenon mixtures from speed-of-sound and burnett P ? T measurements

    Microsoft Academic Search

    J. J. Hurly; J. W. Schmidt; S. J. Boyes; M. R. Moldover

    1997-01-01

    The virial equation of state was determined for helium, xenon, and helium-xenon mixtures for the pressure and temperature\\u000a ranges 0.5 to 5 MPa and 210 to 400 K. Two independent experimental techniques were employed: BurnettP?T measurements and speed-of-sound measurements. The temperature-dependent second and third density virial coefficients for\\u000a pure xenon and the second and third interaction density virial coefficients for

  10. Diffusion NMR Methods Applied to Xenon Gas for Materials Study

    E-print Network

    R. W. Mair; M. S. Rosen; R. Wang; D. G. Cory; R. L. Walsworth

    2002-11-09

    We report initial NMR studies of i) xenon gas diffusion in model heterogeneous porous media, and ii) continuous flow laser-polarized xenon gas. Both areas utilize the Pulsed Gradient Spin Echo techniques in the gas-phase, with the aim of obtaining more sophisticated information than just translational self-diffusion coefficients - a brief overview of this area is provided in the introduction. The heterogeneous or multiple-length scale model porous media consisted of random packs of mixed glass beads of two different sizes. We focus on observing the approach of the time-dependent gas diffusion coefficient, D(t), (an indicator of mean squared displacement) to the long-time asymptote, with the aim of understanding the long-length scale structural information that may be derived from a heterogeneous porous system. The Pade approximation is used to interpolate D(t) data between the short and long time limits. Initial studies of continuous flow laser-polarized xenon gas demonstrate velocity-sensitive imaging of much higher flows than can generally be obtained with liquids (20 - 200 mm/s). Gas velocity imaging is, however, found to be limited to a resolution of about 1 mm/s due to the high diffusivity of gases compared to liquids. We also present the first gas-phase NMR scattering, or diffusive-diffraction, data: namely, flow-enhanced structural features in the echo attenuation data from laser-polarized xenon flowing through a 2 mm glass bead pack.

  11. Hydrodynamic gas mixture separation

    SciTech Connect

    Stolyarov, A.A.

    1982-02-10

    The separation of gas mixtures is the basis of many chemical, petrochemical, and gas processes. Classical separation methods (absorption, adsorption, condensation, and freezing) require cumbersome and complex equipment. No adequate solution is provided by the cheapening and simplification of gas-processing apparatus and separation methods by hydration and diffusion. For example, an apparatus for extracting helium from natural gas by diffusion has a throughput of gas containing 0.45% helium of 117,000 m/sup 3//h and in the first stage has teflon membranes working at a pressure difference of 63.3x10/sup 5/ Pa of area 79,000 m/sup 2/, and the specific cost of the apparatus was 8500 dollars per m/sup 3//h of helium. Therefore, vigorous studies are being conducted on new ways of efficient separation of gas mixtures that are cheaper and simpler. Here we consider a novel method of physically essentially reversible separation of gas mixtures, which involves some features of single-phase supersonic flows.

  12. Monitoring radioactive xenon gas in room air using activated charcoal

    SciTech Connect

    Langford, J.; Thompson, G. (Princess Margaret Hospital for Children, Perth (Australia) Sir Charles Gairdner Hospital, Perth (Australia))

    1990-03-01

    A method for monitoring room air for radioactive xenon gas is described. It uses activated charcoal vials, a vacuum source and a well-type scintillation counter. The method may be adapted for detection and identification of any radioactive gas excluding those with ultra-short half-lives. Sampling room air during xenon-133 ({sup 133}Xe) ventilation lung studies was performed using this technique. The results show that low concentrations of {sup 133}Xe in room air can be reliably detected and that staff exposure to {sup 133}Xe at this institution was within ICRP recommendations.

  13. Applications of controlled-flow laser-polarized xenon gas to porous and granular media study

    E-print Network

    Walsworth, Ronald L.

    Applications of controlled-flow laser-polarized xenon gas to porous and granular media study R. W of continuous flow laser-polarized xenon gas, both in unrestricted tubing, and in a model porous media of continuous flow laser-polarized xenon gas in unrestricted tubing indicate clear diffraction minima resulting

  14. Separation of gas mixtures by thermoacoustic waves.

    SciTech Connect

    Swift, G. W. (Gregory W.); Geller, D. A. (Drew A.)

    2001-01-01

    Imposing sound on a binary gas mixture in a duct separates the two gases along the acoustic-propagation axis. Mole-fraction differences as large as 10% and separation fluxes as high as 0.001 M-squared c, where M is Mach number and c is sound speed, are easily observed. We describe the accidental discovery of this phenomenon in a helium-xenon mixture, subsequent experiments with a helium-argon mixture, and theoretical developments. The phenomenon occurs because a thin layer of the gas adjacent to the wall is immobilized by viscosity while the rest of the gas moves back and forth with the wave, and the heat capacity of the wall holds this thin layer of the gas at constant temperature while the rest of the gas experiences temperature oscillations due to the wave's oscillating pressure. The oscillating temperature gradient causes the light and heavy atoms in the gas to take turns diffusing into and out of the immobilized layer, so that the oscillating motion of the wave outside the immobilized layer tends to carry light-enriched gas in one direction and heavy-enriched gas in the opposite direction. Experiment and theory are in very good agreement for the initial separation fluxes and the saturation mole-fraction differences.

  15. SEPARATION OF GAS MIXTURES BY THERMOACOUSTIC WAVES

    SciTech Connect

    G.W. SWIFT; D.A. GELLER; P.S. SPOOR

    2001-06-01

    Imposing sound on a binary gas mixture in a duct separates the two gases along the acoustic-propagation axis. Mole-fraction differences as large as 10% and separation fluxes as high as 0.001 M-squared c, where M is Mach number and c is sound speed, are easily observed. We describe the accidental discovery of this phenomenon in a helium-xenon mixture, subsequent experiments with a helium-argon mixture, and theoretical developments. The phenomenon occurs because a thin layer of the gas adjacent to the wall is immobilized by viscosity while the rest of the gas moves back and forth with the wave, and the heat capacity of the wall holds this thin layer of the gas at constant temperature while the rest of the gas experiences temperature oscillations due to the wave's oscillating pressure. The oscillating temperature gradient causes the light and heavy atoms in the gas to take turns diffusing into and out of the immobilized layer, so that the oscillating motion of the wave outside the immobilized layer tends to carry light-enriched gas in one direction and heavy-enriched gas in the opposite direction. Experiment and theory are in very good agreement for the initial separation fluxes and the saturation mole-fraction differences.

  16. Molecular Dynamics Calculation of the Viscosity of Xenon Gas

    NASA Astrophysics Data System (ADS)

    Mountain, Raymond D.

    2007-02-01

    The density variation of the viscosity of xenon gas is determined using molecular dynamics simulation with a semi-empirical pair potential fit to low-density gas properties. The gas states ranged in density from 0.37 to 7.62 mol · dm-3, and varied in temperature from 240 -591 K. The simulation results match the kinetic-theory predictions for the model potential at the lowest density, and systematically lie below the experimental values for higher densities. This indicates the need for many-body interactions to accurately predict the viscosity of xenon gas at even moderate densities. An operational criterion for identifying the density region where kinetic theory is appropriate is proposed.

  17. Diffusion NMR methods applied to xenon gas for materials study.

    PubMed

    Mair, R W; Rosen, M S; Wang, R; Cory, D G; Walsworth, R L

    2002-12-01

    We report initial NMR studies of (i) xenon gas diffusion in model heterogeneous porous media and (ii) continuous flow laser-polarized xenon gas. Both areas utilize the pulsed gradient spin-echo (PGSE) techniques in the gas phase, with the aim of obtaining more sophisticated information than just translational self-diffusion coefficients--a brief overview of this area is provided in the Introduction. The heterogeneous or multiple-length scale model porous media consisted of random packs of mixed glass beads of two different sizes. We focus on observing the approach of the time-dependent gas diffusion coefficient, D(t) (an indicator of mean squared displacement), to the long-time asymptote, with the aim of understanding the long-length scale structural information that may be derived from a heterogeneous porous system. We find that D(t) of imbibed xenon gas at short diffusion times is similar for the mixed bead pack and a pack of the smaller sized beads alone, hence reflecting the pore surface area to volume ratio of the smaller bead sample. The approach of D(t) to the long-time limit follows that of a pack of the larger sized beads alone, although the limiting D(t) for the mixed bead pack is lower, reflecting the lower porosity of the sample compared to that of a pack of mono-sized glass beads. The Pade approximation is used to interpolate D(t) data between the short- and long-time limits. Initial studies of continuous flow laser-polarized xenon gas demonstrate velocity-sensitive imaging of much higher flows than can generally be obtained with liquids (20-200 mm s-1). Gas velocity imaging is, however, found to be limited to a resolution of about 1 mm s-1 owing to the high diffusivity of gases compared with liquids. We also present the first gas-phase NMR scattering, or diffusive-diffraction, data, namely flow-enhanced structural features in the echo attenuation data from laser-polarized xenon flowing through a 2 mm glass bead pack. PMID:12807139

  18. Study of argon-based penning gas mixtures for use in proportional counters

    Microsoft Academic Search

    P. C. Agrawal; B. D. Ramsey; M. C. Weisskopf

    1989-01-01

    Results from an experimental investigation of three Penning gas mixtures, namely argon-acetylene (Ar-C2H2), argon-xenon (Ar-Xe) and argon-xenon-trimethylamine (Ar-Xe-TMA), are reported. The measurements, carried out in cylindrical geometry as well as parallel plate geometry detectors, demonstrate that the Ar-C2H2 mixtures show a significant Penning effect even at an acetylene concentration of 10% and provide the best energy resolution among all the

  19. Penning gas mixtures for improving the energy resolution of proportional counters

    SciTech Connect

    Agrawal, P.C.; Ramsey, B.D.

    1989-02-01

    An experimental investigation of the Penning effect in both argon and xenon has been carried out with a variety of quench gases of different ionization potentials. Acetylene with argon and trimethylamine with xenon show the strongest true Penning effect, returning very high gas gains for a given voltage and improved energy resolution over more conventional mixtures. Data for these mixtures, as well as others exhibiting weaker metastable effects, non-metastable Penning effects, and charge transfer through photo-ionization, are presented.

  20. A 20 atmosphere imaging xenon gas scintillation drift chamber

    Microsoft Academic Search

    T. K. Edberg; A. Parsons; B. Sadoulet; S. Weiss; J. Wilkerson; G. Smith

    1992-01-01

    We describe the high pressure xenon imaging gas scintillation drift chamber with waveshifting fiber readout, a novel detector for hard X-ray (30 keV to at least 300 keV) observations. This technique promises good energy resolution (24%\\/&surd;E (keV) FWHM), excellent imaging ( ~ 200 mum FWHM), and very high sensitivity due to large effective area and low backgrounds. We describe a

  1. Study of a zirconium getter for purification of xenon gas

    E-print Network

    Dobi, A; Hall, C; Kaufman, L; Langford, T; Slutsky, S; Yen, Y R

    2010-01-01

    Oxygen, nitrogen and methane purification efficiencies for a common zirconium getter are measured in 1050 Torr of xenon gas. Starting with impurity concentrations near 10^{-6} g/g, the outlet impurity level is found to be less than 120*10^{-12} g/g for O2 and less than 950*10^{-12} g/g for N2. For methane we find residual contamination of the purified gas at concentrations varying over three orders of magnitude, depending on the purifier temperature and the gas flow rate. A slight reduction in the purifier's methane efficiency is observed after 13 mg of this impurity has been absorbed, which we attribute to partial exhaustion of the purifier's capacity for this species. We also find that the purifier's ability to absorb N2 and methane can be extinguished long before any decrease in O2 performance is observed, and slower flow rates should be employed for xenon purification due to the cooling effect that the heavy gas has on the getter.

  2. Applications of controlled-flow laser-polarized xenon gas to porous and granular media study

    Microsoft Academic Search

    R. W. Maira; R. Wang; M. S. Rosen; D. Candela; D. G. Cory; R. L. Walsworth

    We report initial NMR studies of continuous flow laser-polarized xenon gas, both in unrestricted tubing, and in a model porous media. The study uses Pulsed Gradient Spin Echo-based techniques in the gas-phase, with the aim of obtaining more sophisticated information than just translational self-diffusion coefficients. Pulsed Gradient Echo studies of continuous flow laser-polarized xenon gas in unrestricted tubing indicate clear

  3. Ionization and scintillation response of high-pressure xenon gas to alpha particles

    NASA Astrophysics Data System (ADS)

    Álvarez, V.; Borges, F. I. G.; Cárcel, S.; Cebrián, S.; Cervera, A.; Conde, C. A. N.; Dafni, T.; Díaz, J.; Egorov, M.; Esteve, R.; Evtoukhovitch, P.; Fernandes, L. M. P.; Ferrario, P.; Ferreira, A. L.; Freitas, E. D. C.; Gehman, V. M.; Gil, A.; Goldschmidt, A.; Gómez, H.; Gómez-Cadenas, J. J.; González-Díaz, D.; Gutiérrez, R. M.; Hauptman, J.; Hernando Morata, J. A.; Herrera, D. C.; Irastorza, I. G.; Jinete, M. A.; Labarga, L.; Laing, A.; Liubarsky, I.; Lopes, J. A. M.; Lorca, D.; Losada, M.; Luzón, G.; Marí, A.; Martín-Albo, J.; Miller, T.; Moiseenko, A.; Monrabal, F.; Monteiro, C. M. B.; Mora, F. J.; Moutinho, L. M.; Muñoz Vidal, J.; Natal da Luz, H.; Navarro, G.; Nebot-Guinot, M.; Nygren, D.; Oliveira, C. A. B.; Palma, R.; Pérez, J.; Pérez Aparicio, J. L.; Renner, J.; Ripoll, L.; Rodríguez, A.; Rodríguez, J.; Santos, F. P.; dos Santos, J. M. F.; Seguí, L.; Serra, L.; Shuman, D.; Simón, A.; Sofka, C.; Sorel, M.; Toledo, J. F.; Tomás, A.; Torrent, J.; Tsamalaidze, Z.; Vázquez, D.; Veloso, J. F. C. A.; Webb, R.; White, J. T.; Yahlali, N.

    2013-05-01

    High-pressure xenon gas is an attractive detection medium for a variety of applications in fundamental and applied physics. In this paper we study the ionization and scintillation detection properties of xenon gas at 10 bar pressure. For this purpose, we use a source of alpha particles in the NEXT-DEMO time projection chamber, the large scale prototype of the NEXT-100 neutrinoless double beta decay experiment, in three different drift electric field configurations. We measure the ionization electron drift velocity and longitudinal diffusion, and compare our results to expectations based on available electron scattering cross sections on pure xenon. In addition, two types of measurements addressing the connection between the ionization and scintillation yields are performed. On the one hand we observe, for the first time in xenon gas, large event-by-event correlated fluctuations between the ionization and scintillation signals, similar to that already observed in liquid xenon. On the other hand, we study the field dependence of the average scintillation and ionization yields. Both types of measurements may shed light on the mechanism of electron-ion recombination in xenon gas for highly-ionizing particles. Finally, by comparing the response of alpha particles and electrons in NEXT-DEMO, we find no evidence for quenching of the primary scintillation light produced by alpha particles in the xenon gas.

  4. Investigation of the xenon excimer continuum in gas-discharge plasma

    SciTech Connect

    Baranov, I.Y.; Devdariani, A.Z.; Kryukov, N.A. [Univ. of Pervogo Maya, Peterhof (Russian Federation)] [and others

    1995-02-01

    The shape of the spectral band profile of xenon excimer molecule radiation in the near VUV region is studied as a function of the rare gas pressure. Excited states were formed in a pulsed gas discharge plasma is pure xenon. Spectral transitions BO{sub u}{sup +}{r_arrow}XO{sub g}{sup +} and A1{sub u}{r_arrow}XO{sub g}{sup +} were recorded. The spectrum transformation in discharge afterglow is studied. A model describing peculiarities of xenon excimer continuum formation is proposed. 13 refs., 5 figs.

  5. Gas mixtures for spark gap closing switches

    DOEpatents

    Christophorou, L.G.; McCorkle, D.L.; Hunter, S.R.

    1987-02-20

    Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches. 6 figs.

  6. Gas mixtures for spark gap closing switches

    DOEpatents

    Christophorou, Loucas G. (Oak Ridge, TN); McCorkle, Dennis L. (Knoxville, TN); Hunter, Scott R. (Oak Ridge, TN)

    1988-01-01

    Gas mixtures for use in spark gap closing switches comprised of fluorocarbons and low molecular weight, inert buffer gases. To this can be added a third gas having a low ionization potential relative to the buffer gas. The gas mixtures presented possess properties that optimized the efficiency spark gap closing switches.

  7. Xenon excited state density measurements in electron beam pumped XeCl laser mixtures

    SciTech Connect

    Kannari, F.; Kimura, W.D.; Seamans, J.F.; Guyer, D.R.

    1987-12-14

    Time-dependent density measurements of the lowest xenon excited states (5p/sup 5/6s) in electron beam (e-beam) pumped XeCl laser mixtures (nonlasing) are performed using pulsed hook interferometry. The e-beam pulse length is approx. =0.45 ..mu..s (full width at half-maximum) with an average excitation rate of approx. =250 kW/cm/sup 3/. Density differences (..delta..N*) of transitions at 823.2 nm (6s(3/2)/sup 0//sub 2/ --6p(3/2)/sub 2/), 828.0 nm (6s(3/2)/sup 0//sub 1/ --6p(1/2)/sub 0/), and 840.9 nm (6s(3/2)/sup 0//sub 2/ --6p(3/2)/sub 1/) are obtained for various HCl and Xe concentrations. For a 98.3% Ne/1.5% Xe/0.16% HCl mixture at 3000 Torr, ..delta..N* (823.2 nm) and ..delta..N*(828.0 nm) are relatively constant at approx. =3 x 10/sup 14/ and approx. =1.7 x 10/sup 14/ cm/sup -3/, respectively. At lower initial HCl concentrations, the ..delta..N*(823.2 nm) density starts out similar to the 0.16% HCl case, but tends to increase dramatically during the e-beam pulse. For a 0.04% HCl mixture, a ..delta..N*(840.9 nm) density of approx. =4.5 x 10/sup 15/ cm/sup -3/ is measured at the end of the e-beam pulse. Preliminary comparisons of the data with a computer model show good agreement for HCl concentrations greater than or equal to0.16%, but disagreements at leaner concentrations.

  8. arXiv:1106.1812v1[physics.ins-det]9Jun2011 A Xenon Gas Purity Monitor for EXO

    E-print Network

    Gratta, Giorgio

    arXiv:1106.1812v1[physics.ins-det]9Jun2011 A Xenon Gas Purity Monitor for EXO A. Dobia , C. Halla discuss the design, operation, and calibration of two versions of a xenon gas purity monitor (GPM. The EXO-200 detector is a liquid xenon TPC, while the successor experiments may be based on liquid or gas

  9. Separation of gas mixtures by centrifugation

    NASA Technical Reports Server (NTRS)

    Park, C.; Love, W. L.

    1972-01-01

    Magnetohydrodynamic (MHD) centrifuge utilizing electric currents and magnetic fields produces a magnetic force which develops supersonic rotational velocities in gas mixtures. Device is superior to ordinary centrifuges because rotation of gas mixture is produced by MHD force rather than mechanical means.

  10. Self-Quenching Geiger Counters containing Mixtures of Permanent Gases

    Microsoft Academic Search

    A. J. L. Collinson; I. C. Demetsopoullos; J. A. Dennis; J. M. Zarzycki

    1960-01-01

    WE feel that the xenon-oxygen phenomenon referred to by Dr. Riedel, although interesting, is only of importance in mixtures where xenon is the main gas. While such an effect is possibly a small contributory factor in the quenching mechanism of the argon-xenon-oxygen-nitrogen mixtures which we have investigated, our results show that the important mechanism is the interaction of xenon with

  11. Emission characteristics and parameters of gas-discharge plasma in mixtures of heavy inert gases with chlorine

    Microsoft Academic Search

    A. K. Shuaibov; A. N. Malinin

    2009-01-01

    The ultraviolet (UV) radiation from longitudinal glow-discharge plasma in three- and four-component mixtures of argon, krypton,\\u000a and xenon with chlorine has been investigated. The total radiation of Ar, Kr, and Xe monochlorides and chlorine molecules\\u000a in the spectral range 170–310 nm has been optimized with respect to the composition and the pressure of gas mixtures, as well\\u000a as the discharge

  12. Emission characteristics and parameters of gas-discharge plasma in mixtures of heavy inert gases with chlorine

    Microsoft Academic Search

    A. K. Shuaibov; A. N. Malinin

    2009-01-01

    The ultraviolet (UV) radiation from longitudinal glow-discharge plasma in three- and four-component mixtures of argon, krypton, and xenon with chlorine has been investigated. The total radiation of Ar, Kr, and Xe monochlorides and chlorine molecules in the spectral range 170-310 nm has been optimized with respect to the composition and the pressure of gas mixtures, as well as the discharge

  13. Separation of gas mixtures including hydrogen

    SciTech Connect

    Krishnamurthy, R.; Lerner, S.L.; Shukla, Y.; Stokley, A.G.

    1993-08-10

    A process is described of separating a gas mixture comprising at least three components into three different fractions by pressure swing adsorption, comprising repeatedly performing a cycle including: passing said gas mixture sequentially through first and second adsorptive regions on each of which a second component of the mixture is more strongly adsorbed than a first component, but less strongly adsorbed than a third component; withdrawing a first fraction enriched in said first component from the downstream end of the second adsorptive region; stopping admission of the said gas mixture to the first adsorptive region; withdrawing a second fraction enriched in the second component from the downstream end of the first adsorptive region and from the upstream end of the second adsorptive region into a common pipeline; and withdrawing a third fraction enriched in the third component from the upstream end of the first adsorptive region.

  14. CONTROLLED COMBUSTION OF LOW-QUALITY GAS MIXTURES

    Microsoft Academic Search

    Malinen Kaisu; Järvinen Mika; Saari Kari; Lampinen Markku; Fogelholm Carl-Johan; Riikonen Arto

    The objective of this work was to experimentally de termine the lowest levels of methane content in gas mixtures that would still en able controlled combustion using a commercial standard gas burner. A gas mixture is of low quality when it is uncertai n whether the mixture will ignite or maintain stable combustion. Such low-quality gas mixtures can typically include

  15. NMR studies of laser-polarized xenon gas flow

    Microsoft Academic Search

    R. W. Mair; R. Wang; M. S. Rosen; R. L. Walsworth; D. Candela

    2003-01-01

    NMR techniques that are commonly used to measure diffusion can also be used to measure fluid velocity and\\/or acceleration. In recent years, laser-polarized noble gas NMR has developed into a powerful tool for spin density and diffusion imaging; however few attempts have been made to study gas flow by NMR. We report initial NMR velocity measurements of continuously flowing laser-polarized

  16. Secondary scintillation yield in high-pressure xenon gas for neutrinoless double beta decay (0???) search

    NASA Astrophysics Data System (ADS)

    Freitas, E. D. C.; Monteiro, C. M. B.; Ball, M.; Gómez-Cadenas, J. J.; Lopes, J. A. M.; Lux, T.; Sánchez, F.; dos Santos, J. M. F.

    2010-02-01

    The search for neutrinoless double beta decay (0???) is an important topic in contemporary physics with many active experiments. New projects are planning to use high-pressure xenon gas as both source and detection medium. The secondary scintillation processes available in noble gases permit large amplification with negligible statistical fluctuations, offering the prospect of energy resolution approaching the Fano factor limit. This Letter reports results for xenon secondary scintillation yield, at room temperature, as a function of electric field in the gas scintillation gap for pressures ranging from 2 to 10 bar. A Large Area Avalanche Photodiode (LAAPD) collected the VUV secondary scintillation produced in the gas. X-rays directly absorbed in the LAAPD are used as a reference for determining the number of charge carriers produced by the scintillation pulse and, hence, the number of photons impinging the LAAPD. The number of photons produced per drifting electron and per kilovolt, the so-called scintillation amplification parameter, displays a small increase with pressure, ranging from 141±6 at 2 bar to 170±10 at 8 bar. In our setup, this parameter does not increase above 8 bar due to non-negligible electron attachment. The results are in good agreement with those presented in the literature in the 1 to 3 bar range. The increase of the scintillation amplification parameter with pressure for high gas densities has been also observed in former work at cryogenic temperatures.

  17. Inert gas: Vapor mixtures in thermoacoustics

    Microsoft Academic Search

    William Victor Slaton

    2001-01-01

    An analytic solution of sound propagation in wet-walled tubes with a temperature gradient will be presented. The tube contains an inert gas-vapor mixture with a thin layer of condensed vapor coating the tube wall. The vapor phase condenses and evaporates from this layer during an acoustic cycle. This phased evaporation and condensation modifies traditional energy density and wave number equations.

  18. Electronic energy transfer in rare gas mixtures

    Microsoft Academic Search

    A. Szoke; Y. Binur; R. Shuker; E. Zamir

    1974-01-01

    In a spectroscopic study carried out in this laboratory a new energy transfer mechanism from a noble gas molecule to an atom was identified. This transfer process is similar to the Penning ionization in the sense that it populates energy levels of a guest atom selectively within a certain range. A mixture of Ar:Xe was studied. This report discusses these

  19. Radioxenon production through neutron irradiation of stable xenon gas

    SciTech Connect

    Haas, Derek A.; Biegalski, Steven R.; Foltz Biegalski, Kendra M.

    2009-12-01

    The Spectral Deconvolution Analysis Tool (SDAT) software was developed to improve counting statistics and detection limits for nuclear explosion radionuclide measurements. SDAT utilizes spectral deconvolution spectroscopy techniques and can analyze both ?-? coincidence spectra for radioxenon isotopes and high-resolution HPGe spectra from aerosol monitors. The deconvolution algorithm of the SDAT requires a library of ?-? coincidence spectra of individual radioxenon isotopes to determine isotopic ratios in a sample. In order to get experimentally produced spectra of the individual isotopes we have irradiated enriched samples of 130Xe, 132Xe, and 134Xe gas with a neutron beam from the TRIGA reactor at The University of Texas. The samples produced were counted in an Automated Radioxenon Sampler/Analyzer (ARSA) style ?-? coincidence detector. The spectra produced show that this method of radioxenon production yields samples with very high purity of the individual isotopes for 131mXe and 135Xe and a sample with a substantial 133mXe to 133Xe ratio.

  20. Separation of gas mixtures by supported complexes

    SciTech Connect

    Nelson, D.A.; Lilga, M.A.; Hallen, R.T.; Lyke, S.E.

    1986-08-01

    The goal of this program is to determine the feasibility of solvent-dissolved coordination complexes for the separation of gas mixtures under bench-scale conditions. In particular, mixtures such as low-Btu gas are examined for CO and H/sub 2/ separation. Two complexes, Pd/sub 2/(dpm)/sub 2/Br/sub 2/ and Ru(CO)/sub 2/(PPh/sub 3/)/sub 3/, were examined in a bench-scale apparatus for the separation of binary (CO-N/sub 2/ or H/sub 2/-N/sub 2/) and quinary (H/sub 2/, CO, CO/sub 2/, CH/sub 4/, and N/sub 2/) mixtures. The separation of CO-N/sub 2/ was enhanced by the presence of the palladium complex in the 1,1,2-trichloroethane (TCE) solvent, especially at high gas and low liquid rates. The five-component gas mixture separation with the palladium complex in TCE provided quite unexpected results based on physical solubility and chemical coordination. The complex retained CO, while the solvent retained CO/sub 2/, CH/sub 4/, and N/sub 2/ to varying degrees. This allowed the hydrogen content to be enhanced due to its low solubility in TCE and inertness to the complex. Thus, a one-step, hydrogen separation can be achieved from gas mixtures with compositions similar to that of oxygen-blown coal gas. A preliminary economic evaluation of hydrogen separation was made for a system based on the palladium complex. The palladium system has a separation cost of 50 to 60 cents/MSCF with an assumed capital investment of $1.60/MSCF of annual capacity charged at 30% per year. This assumes a 3 to 4 year life for the complex. Starting with a 90% hydrogen feed, PSA separation costs are in the range of 30 to 50 cents/MSCF. The ruthenium complex was not as successful for hydrogen or carbon monoxide separation due to unfavorable kinetics. The palladium complex was found to strip hydrogen gas from H/sub 2/S. The complex could be regenerated with mild oxidants which removed the sulfur as SO/sub 2/. 24 refs., 26 figs., 10 tabs.

  1. The NEXT experiment: A high pressure xenon gas TPC for neutrinoless double beta decay searches

    E-print Network

    D. Lorca; J. Martín-Albo; F. Monrabal; for the NEXT Collaboration

    2012-10-15

    Neutrinoless double beta decay is a hypothetical, very slow nuclear transition in which two neutrons undergo beta decay simultaneously and without the emission of neutrinos. The importance of this process goes beyond its intrinsic interest: an unambiguous observation would establish a Majorana nature for the neutrino and prove the violation of lepton number. NEXT is a new experiment to search for neutrinoless double beta decay using a radiopure high-pressure xenon gas TPC, filled with 100 kg of Xe enriched in Xe-136. NEXT will be the first large high-pressure gas TPC to use electroluminescence readout with SOFT (Separated, Optimized FuncTions) technology. The design consists in asymmetric TPC, with photomultipliers behind a transparent cathode and position-sensitive light pixels behind the anode. The experiment is approved to start data taking at the Laboratorio Subterr\\'aneo de Canfranc (LSC), Spain, in 2014.

  2. The NEXT experiment: A high pressure xenon gas TPC for neutrinoless double beta decay searches

    NASA Astrophysics Data System (ADS)

    Lorca, D.; Martín-Albo, J.; Monrabal, F.; NEXT Collaboration

    2013-08-01

    Neutrinoless double beta decay (??0?) is a hypothetical, very slow nuclear transition in which two neutrons undergo beta decay simultaneously and without the emission of neutrinos. The importance of this process goes beyond its intrinsic interest: an unambiguous observation would establish a Majorana nature for the neutrino and prove the violation of lepton number. NEXT is a new experiment to search for neutrinoless double beta decay using a radiopure high-pressure xenon gas TPC, filled with 100 kg of Xe enriched in Xe-136. NEXT will be the first large high-pressure gas TPC to use electroluminescence readout with SOFT (Separated, Optimized FuncTions) technology. The design consists in asymmetric TPC, with photomultipliers behind a transparent cathode and position-sensitive light pixels behind the anode. The experiment is approved to start data taking at the Laboratorio Subterráneo de Canfranc (LSC), Spain, in 2014.

  3. Shear viscosity of hadronic gas mixtures

    E-print Network

    K. Itakura; O. Morimatsu; H. Otomo

    2008-05-12

    We investigate the effects of baryon chemical potential \\mu on the shear viscosity coefficient \\eta and the viscosity to entropy density ratio \\eta/s of a pion-nucleon gas mixture. We find that \\eta is an increasing function of T and \\mu, while the ratio \\eta/s turns to a decreasing function in a wide region of T-\\mu plane. In the kinematical region we studied, the smallest value of \\eta/s is about 0.3.

  4. PVT measurements for five natural gas mixtures 

    E-print Network

    Simon, Philip Parayil

    1991-01-01

    OF FIGURES . V11 LIST OF TABLES INTRODUCTION . EXPERIMENT Method Apparatus Data Analysis Sample 10 RESULTS AND DISCUSSIONS 12 CONCLUSIONS 26 LITERATURE CITED 27 APPENDIX A: THE COOLING SYSTEM 29 APPENDIX B: VOLUMETRIC DATA . . 35 TABLE... OF CONTENTS (Continued) Page APPENDIX C: VOLUMETRIC DATA FROM PREVIOUS WORK 47 APPENDIX D 53 VITA 54 LIST OF FIGURES Page Figure 1. Schematic of the Burnett apparatus. Figure 2. Compressibility factors for the Amarillo gas mixture. Figure 3...

  5. Noble gas mixture hollow cathode lasers

    Microsoft Academic Search

    M. Jánossy; L. Csillag; Z. Donkó; K. Rózsa

    1993-01-01

    A review of noble gas mixture ion lasers operating cw in hollow cathode discharges is given. The basic properties of hollow\\u000a cathode discharges and the main principles of tube construction are described. For the He?Kr, He?Ar and He?Ne?Xe systems laser\\u000a transitions, excitation mechanisms, operation of the lasers and questions of lasers for practical use are discussed. The single\\u000a frequency operation

  6. IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES

    SciTech Connect

    Jason M. Keith

    2005-02-01

    This report describes work performed during a thirty month project which involves the production of dimethyl ether (DME) on-site for use as an ignition-improving additive in a compression-ignition natural gas engine. A single cylinder spark ignition engine was converted to compression ignition operation. The engine was then fully instrumented with a cylinder pressure transducer, crank shaft position sensor, airflow meter, natural gas mass flow sensor, and an exhaust temperature sensor. Finally, the engine was interfaced with a control system for pilot injection of DME. The engine testing is currently in progress. In addition, a one-pass process to form DME from natural gas was simulated with chemical processing software. Natural gas is reformed to synthesis gas (a mixture of hydrogen and carbon monoxide), converted into methanol, and finally to DME in three steps. Of additional benefit to the internal combustion engine, the offgas from the pilot process can be mixed with the main natural gas charge and is expected to improve engine performance. Furthermore, a one-pass pilot facility was constructed to produce 3.7 liters/hour (0.98 gallons/hour) DME from methanol in order to characterize the effluent DME solution and determine suitability for engine use. Successful production of DME led to an economic estimate of completing a full natural gas-to-DME pilot process. Additional experimental work in constructing a synthesis gas to methanol reactor is in progress. The overall recommendation from this work is that natural gas to DME is not a suitable pathway to improved natural gas engine performance. The major reasons are difficulties in handling DME for pilot injection and the large capital costs associated with DME production from natural gas.

  7. Dusty Plasma Structures in Gas Mixtures

    SciTech Connect

    Popova, D. V.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E. [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya Str. 13/19, build 2, 125412 Moscow (Russian Federation); Maiorov, S. A. [A. M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov Str. 38, 119991 Moscow (Russian Federation)

    2008-09-07

    The possibility of attainment of large Mach numbers is analyzed for the case of heavy ions drifting in a light gas. Under conditions of typical experiments with dust structures in plasmas, the use of the mixture of light and heavy gases is shown to make it possible to suppress the ion heating in the electric field and to form supersonic flows characterized by large Mach numbers. The drift of krypton ions in helium is considered as an example. Experiments with dc glow discharge at 1-10% of Kr show that the transition to the discharge in mixture leads to increase of interaction anisotropy and reinforcement of coupling of dust particles in the direction of ion drift. On the other hand, under certain conditions the phenomenon of abnormal 'heating' of dust particles was observed when the particles can obtain high kinetic energy which is several orders of magnitude higher than typical.

  8. Experimental investigation of the critical ionization velocity in gas mixtures

    Microsoft Academic Search

    I. Axnas

    1978-01-01

    Results are summarized for systematic experiments performed to determine the critical ionization velocity (E\\/B) for gas mixtures as a function of mixing ratio for several different binary gas mixtures. In the experiments a coaxial plasma gun with an azimuthal magnetic field and a radial discharge current was used to measure E\\/B for gas-mixture discharge as a function of neutral gas

  9. Velocity slip of gas mixtures in free jet expansions

    Microsoft Academic Search

    P. Raghuraman; P. Davidovits

    1978-01-01

    A theoretical model is presented for calculating the species velocity of a gas mixture expanding as a free jet through a sonic orifice into vacuum. Calculations were done for two systems (a) a binary gas mixture of argon seeded in helium, and (b) a ternary mixture of uranium hexafluoride isotopes seeded in helium. The results are compared with previous calculations

  10. HDT mixtures treatment strategies by gas chromatography

    SciTech Connect

    Laquerbe, C.; Contreras, S.; Demoment, J. [Commissariat a l'Energie Atomique - CEA/Valduc, F-21121 Is sur Tille (France)

    2008-07-15

    Gas phase chromatographic processes are of interest for the separation of hydrogen isotopes from an HDT mixture. For a certain quantity, they are very competitive and present several benefits. Nevertheless no active packing material allows to have simultaneously good enrichment performances for tritium production and high decontamination capabilities for HD gases. The influence of the packing material is first described in this article. Then two specific processes (TCAP and Reverse Chromatography), each well adapted to perform one target, are presented. Finally, the problematic to propose an optimized treatment scheme associating these two processes is formulated. (authors)

  11. Hyperpolarized Xenon-129 Gas-Exchange Imaging of Lung Microstructure: First Case Studies in Subjects with Obstructive Lung Disease

    PubMed Central

    Dregely, Isabel; Mugler, John P.; Ruset, Iulian C.; Altes, Talissa A.; Mata, Jaime F.; Miller, G. Wilson; Ketel, Jeffrey; Ketel, Steve; Distelbrink, Jan; Hersman, F.W.; Ruppert, Kai

    2011-01-01

    Purpose To develop and test a method to non-invasively assess the functional lung microstructure. Materials and Methods The Multiple exchange time Xenon polarization Transfer Contrast technique (MXTC) encodes xenon gas-exchange contrast at multiple delay times permitting two lung-function parameters to be derived: 1) MXTC-F, the long exchange-time depolarization value, which is proportional to the tissue to alveolar-volume ratio and 2) MXTC-S, the square root of the xenon exchange-time constant, which characterizes thickness and composition of alveolar septa. Three healthy volunteers, one asthmatic and two COPD (GOLD stage I and II) subjects were imaged with MXTC MRI. In a subset of subjects, hyperpolarized xenon-129 ADC MRI and CT imaging were also performed. Results The MXTC-S parameter was found to be elevated in subjects with lung disease (p-value = 0.018). In the MXTC-F parameter map it was feasible to identify regional loss of functional tissue in a COPD patient. Further, the MXTC-F map showed excellent regional correlation with CT and ADC (? ? 0.90) in one COPD subject. Conclusion The functional tissue-density parameter MXTC-F showed regional agreement with other imaging techniques. The newly developed parameter MXTC-S, which characterizes the functional thickness of alveolar septa, has potential as a novel biomarker for regional parenchymal inflammation or thickening. PMID:21509861

  12. THEORETICAL STUDY ON THE INTERACTION BETWEEN XENON AND POSITIVE SILVER CLUSTERS IN GAS PHASE AND ON THE (001) CHABAZITE SURFACE

    SciTech Connect

    Hunter, D.

    2009-03-16

    A systematic study on the adsorption of xenon on silver clusters in the gas phase and on the (001) surface of silver-exchanged chabazite is reported. Density functional theory at the B3LYP level with the cluster model was employed. The results indicate that the dominant part of the binding is the {sigma} donation, which is the charge transfer from the 5p orbital of Xe to the 5s orbital of Ag and is not the previously suggested d{sub {pi}}-d{sub {pi}} back-donation. A correlation between the binding energy and the degree of {sigma} donation is found. Xenon was found to bind strongly to silver cluster cations and not to neutral ones. The binding strength decreases as the cluster size increases for both cases, clusters in the gas-phase and on the chabazite surface. The Ag{sup +} cation is the strongest binding site for xenon both in gas phase and on the chabazite surface with the binding energies of 73.9 and 14.5 kJ/mol, respectively. The results also suggest that the smaller silver clusters contribute to the negative chemical shifts observed in the {sup 129}Xe NMR spectra in experiments.

  13. Transport Properties of operational gas mixtures used at LHC

    E-print Network

    Yasser Assran; Archana Sharma

    2011-10-31

    This report summarizes some useful data on the transport characteristics of gas mixtures which are required for detection of charged particles in gas detectors. We try to replace Freon used for RPC detector in the CMS experiment with another gas while maintaining the good properties of the Freon gas mixture unchanged. We try to switch to freonless gas mixture because Freon is not a green gas, it is very expensive and its availability is decreasing. Noble gases like Ar, He, Ne and Xe (with some quenchers like carbon dioxide, methane, ethane and isobutene) are investigated. Transport parameters like drift velocity, diffusion, Townsend coefficient, attachment coefficient and Lorentz angle are computed using Garfield software for different gas mixtures and compared with experimental data.

  14. The Narrow Pulse Approximation and long length scale determination in xenon gas diffusion NMR studies of model porous media

    E-print Network

    R. W. Mair; P. N. Sen; M. D. Hurlimann; S. Patz; D. G. Cory; R. L. Walsworth

    2002-11-10

    We report a systematic study of xenon gas diffusion NMR in simple model porous media: random packs of mono-sized glass beads, and focus on three specific areas peculiar to gas-phase diffusion. These topics are: (i) diffusion of spins on the order of the pore dimensions during the application of the diffusion encoding gradient pulses in a PGSE experiment (breakdown of the 'narrow pulse approximation' and imperfect background gradient cancellation), (ii) the ability to derive long-length scale structural information, and (iii) effects of finite sample size. We find that the time-dependent diffusion coefficient, D(t), of the imbibed xenon gas at short diffusion times in small beads is significantly affected by the gas pressure. In particular, as expected, we find smaller deviations between measured D(t) and theoretical predictions as the gas pressure is increased, resulting from reduced diffusion during the application of the gradient pulse. The deviations are then completely removed when water D(t) is observed in the same samples. The use of gas also allows us to probe D(t) over a wide range of length scales, and observe the long-time asymptotic limit which is proportional to the inverse tortuosity of the sample, as well as the diffusion distance where this limit takes effect (~ 1 - 1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and long time limits, allowing us to explore deviations from the expected behaviour at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and short time asymptotic limits yields a fitted length scale (the "Pade length"), which is found to be ~ 0.13b for all bead packs, where b is the bead diameter.

  15. Separation of gas mixtures by supported complexes

    SciTech Connect

    Nelson, D.A.; Lilga, M.A.

    1986-12-01

    A system was investigated that catalyzes the dehydrogenation of alcohols and the hydrogenation of ketones. Such a catalyst, if used in a membrane containing an alcohol solvent, might be of use in selective H/sub 2/ separation from gas mixtures. The dehydrogenation of cyclohexanol and 2-octanol were studied using a RhCl/sub 3//SnCl/sub 2//LiCl catalyst system. These alcohols are dehydrogenated at rates that are initially rapid, but which gradually slow to a stop. The decrease in rate of H/sub 2/ evolution is a result of the establishment of an equilibrium between the alcohol and the liberated hydrogen and ketone. At 150/sup 0/C, cyclohexanol has the fastest rate of dehydrogenation. Several dehydrogenation/hydrogenation cycles have been carried out using this alcohol over a period of one week without serious catalyst deactivation or side reactions. Initial tests of the catalyst dissolved in cyclohexanol within two membranes were inconclusive. An anion exchange membrane was not suitably wetted by the catalyst solution and Celgard/sup TM/, which was wetted, could not be kept wet at 150/sup 0/C under flow conditions in the membrane cell. 9 refs., 3 figs., 1 tab.

  16. Emission characteristics and parameters of gas-discharge plasma in mixtures of heavy inert gases with chlorine

    NASA Astrophysics Data System (ADS)

    Shuaibov, A. K.; Malinin, A. N.

    2009-04-01

    The ultraviolet (UV) radiation from longitudinal glow-discharge plasma in three- and four-component mixtures of argon, krypton, and xenon with chlorine has been investigated. The total radiation of Ar, Kr, and Xe monochlorides and chlorine molecules in the spectral range 170-310 nm has been optimized with respect to the composition and the pressure of gas mixtures, as well as the discharge current. The mean output power, the electric power of discharge, and the efficiency of a broadband low-pressure exciplex halogen lamp have been determined. Parameters of the glow discharge in Ar-Kr-Cl2 and Kr-Xe-Cl2 mixtures have been simulated numerically. The electron energy distribution functions have been determined through the solution of the Boltzmann kinetic equation. These functions have been used to calculate the plasma parameters, namely, electron transfer characteristics, specific losses of discharge power for electronic processes, and ionization and attachment coefficients.

  17. Spot mode operation of a helium-xenon discharge for lighting

    Microsoft Academic Search

    J. Winter; H. Lange; I. A. Porokhova; F. Sigeneger; D. Uhrlandt

    2007-01-01

    A dc low-pressure discharge in a helium-xenon mixture with the cathode spot on a flat oxide cathode has been investigated. The temperature of the cathode surface in the vicinity of the spot was determined experimentally. Furthermore, the gas temperature and the spatial density profile of the xenon 1s5 metastable atoms were measured in front of the spot. A fluid model

  18. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...certain fuel mixtures containing natural gas or petroleum. 503.38 Section...certain fuel mixtures containing natural gas or petroleum. (a) Eligibility...petitioner proposes to use a mixture of natural gas or petroleum and an alternate...

  19. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...certain fuel mixtures containing natural gas or petroleum. 503.38 Section...certain fuel mixtures containing natural gas or petroleum. (a) Eligibility...petitioner proposes to use a mixture of natural gas or petroleum and an alternate...

  20. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...certain fuel mixtures containing natural gas or petroleum. 503.38 Section...certain fuel mixtures containing natural gas or petroleum. (a) Eligibility...petitioner proposes to use a mixture of natural gas or petroleum and an alternate...

  1. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...certain fuel mixtures containing natural gas or petroleum. 503.38 Section...certain fuel mixtures containing natural gas or petroleum. (a) Eligibility...petitioner proposes to use a mixture of natural gas or petroleum and an alternate...

  2. Inferential determination of various properties of a gas mixture

    DOEpatents

    Morrow, Thomas B. (San Antonio, TX); Behring, II, Kendricks A. (Torrance, CA)

    2007-03-27

    Methods for inferentially determining various properties of a gas mixture, when the speed of sound in the gas is known at an arbitrary temperature and pressure. The method can be applied to natural gas mixtures, where the known parameters are the sound speed, temperature, pressure, and concentrations of any dilute components of the gas. The method uses a set of reference gases and their calculated density and speed of sound values to estimate the density of the subject gas. Additional calculations can be made to estimate the molecular weight of the subject gas, which can then be used as the basis for heating value calculations. The method may also be applied to inferentially determine density and molecular weight for gas mixtures other than natural gases.

  3. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The sample cell at the heart of CVX-2 will sit inside a thermostat providing three layers of insulation. The cell itself comprises a copper body that conducts heat efficiently and smoothes out thermal variations that that would destroy the xenon's uniformity. Inside the cell, the oscillating screen viscometer element is supported between two pairs of electrodes that deflect the screen and then measure screen motion.

  4. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Because xenon near the critical point will collapse under its own weight, experiments on Earth (green line) are limited as they get closer (toward the left) to the critical point. CVX in the microgravity of space (red line) moved into unmeasured territory that scientists had not been able to reach.

  5. New approach in direct-simulation of gas mixtures

    NASA Technical Reports Server (NTRS)

    Chung, Chan-Hong; De Witt, Kenneth J.; Jeng, Duen-Ren

    1991-01-01

    Results are reported for an investigation of a new direct-simulation Monte Carlo method by which energy transfer and chemical reactions are calculated. The new method, which reduces to the variable cross-section hard sphere model as a special case, allows different viscosity-temperature exponents for each species in a gas mixture when combined with a modified Larsen-Borgnakke phenomenological model. This removes the most serious limitation of the usefulness of the model for engineering simulations. The necessary kinetic theory for the application of the new method to mixtures of monatomic or polyatomic gases is presented, including gas mixtures involving chemical reactions. Calculations are made for the relaxation of a diatomic gas mixture, a plane shock wave in a gas mixture, and a chemically reacting gas flow along the stagnation streamline in front of a hypersonic vehicle. Calculated results show that the introduction of different molecular interactions for each species in a gas mixture produces significant differences in comparison with a common molecular interaction for all species in the mixture. This effect should not be neglected for accurate DSMC simulations in an engineering context.

  6. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Shear thirning will cause a normally viscous fluid -- such as pie filling or whipped cream -- to deform and flow more readily under high shear conditions. In shear thinning, a pocket of fluid will deform and move one edge forward, as depicted here.

  7. Energy dependence of proton-induced xenon fragmentation and the approach to liquid-gas criticality in nuclear matter

    SciTech Connect

    Mahi, M.; Bujak, A.T.; Carmony, D.D.; Chung, Y.H.; Gutay, L.J.; Hirsch, A.S.; Paderewski, G.L.; Porile, N.T.; Sangster, T.C.; Scharenberg, R.P.; and others

    1988-05-09

    Cross sections ascribed to a multifragmentation process have been obtained from the measured fragment yields (3less than or equal toZ/sub f/less than or equal to14) in proton-xenon interactions (1less than or equal toE/sub p/less than or equal to20 GeV). The variation of the yields with both mass and bombarding energy can be understood by use of the droplet model of the liquid-gas phase transition. With increasing energy, this model indicates that multifragmentation occurs first in the mechanical-instability region, next in the supersaturated vapor, and fianally in the critical region.

  8. Not adiabatic temperature of combustion gas-air mixture

    NASA Astrophysics Data System (ADS)

    Iovleva, O. V.

    2015-06-01

    In the present work was carried out thermodynamic analysis, the purpose of which was to determine the formula for calculating the temperature of combustion gas-air mixture in non-adiabatic conditions.

  9. Xenon Filled Silicon Germanium Thermoelectric Generators

    NASA Technical Reports Server (NTRS)

    Dewinter, F.

    1972-01-01

    An analysis is presented that shows the desirability and feasibility of using a xenon fill in the initial stages of operation of a silicon-germanium radioisotope thermoelectric generator to be used in outer-planetary exploration. The xenon cover gas offers protection against oxidation and against material sublimation, and allows the generator to deliver required power throughout the prelaunch and launch phases. The protective mechanisms afforded by the xenon cover gas and the mechanization of a xenon supply system are also discussed.

  10. Simultaneous magnetic resonance imaging of ventilation distribution and gas uptake in the human lung using hyperpolarized xenon-129

    PubMed Central

    Mugler, John P.; Altes, Talissa A.; Ruset, Iulian C.; Dregely, Isabel M.; Mata, Jaime F.; Miller, G. Wilson; Ketel, Stephen; Ketel, Jeffrey; Hersman, F. William; Ruppert, Kai

    2010-01-01

    Despite a myriad of technical advances in medical imaging, as well as the growing need to address the global impact of pulmonary diseases, such as asthma and chronic obstructive pulmonary disease, on health and quality of life, it remains challenging to obtain in vivo regional depiction and quantification of the most basic physiological functions of the lung—gas delivery to the airspaces and gas uptake by the lung parenchyma and blood—in a manner suitable for routine application in humans. We report a method based on MRI of hyperpolarized xenon-129 that permits simultaneous observation of the 3D distributions of ventilation (gas delivery) and gas uptake, as well as quantification of regional gas uptake based on the associated ventilation. Subjects with lung disease showed variations in gas uptake that differed from those in ventilation in many regions, suggesting that gas uptake as measured by this technique reflects such features as underlying pathological alterations of lung tissue or of local blood flow. Furthermore, the ratio of the signal associated with gas uptake to that associated with ventilation was substantially altered in subjects with lung disease compared with healthy subjects. This MRI-based method provides a way to quantify relationships among gas delivery, exchange, and transport, and appears to have significant potential to provide more insight into lung disease. PMID:21098267

  11. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of liquid xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Resembling a tiny bit of window screen, the oscillator at the heart of CVX-2 will vibrate between two pairs of paddle-like electrodes. The slight bend in the shape of the mesh has no effect on the data. What counts are the mesh's displacement in the xenon fluid and the rate at which the displacement dampens. The unit shown here is encased in a small test cell and capped with a sapphire windown to contain the xenon at high pressure.

  12. Reduced viscosity interpreted for fluid/gas mixtures

    NASA Technical Reports Server (NTRS)

    Lewis, D. H.

    1981-01-01

    Analysis predicts decrease in fluid viscosity by comparing pressure profile of fluid/gas mixture with that of power-law fluid. Fluid is taken to be viscous, non-Newtonian, and incompressible; the gas to be ideal; the flow to be inertia-free, isothermal, and one dimensional. Analysis assists in design of flow systems for petroleum, coal, polymers, and other materials.

  13. Effects of Lasering upon the Electron Gas and Excited-State Populations in Xenon Discharges

    Microsoft Academic Search

    R. J. Freiberg; L. A. Weaver

    1967-01-01

    Spatially resolved electron density measurements are reported for dc-excited xenon laser discharges over a pressure range of 12.5 to 25.5 mTorr. Due to electrophoretic effects within the closed capillary tube, anode-directed gradients in electron density are established which affect local population inversions. The influence of lasering upon these discharges is investigated experimentally by using a 3.51-? (5d33?6p22) laser whose optical

  14. Portable Device for Preparation and Delivery of Gas Mixtures

    PubMed Central

    Misaghi, I. J.; Stowell, L. J.

    1991-01-01

    A simple, portable device for the preparation and delivery of gas mixtures has been designed and constructed. The basic feature of the device is the use of gas flow controllers to maintain stable flow rates over a wide range of downstream pressures, instead of the capillary tubes and water-filled barostats commonly used in gas-mixing devices. Elimination of the barostat avoids problems such as water leakage, the loss of gases through the barostat, and changes in gas pressure due to evaporative loss of water from the barostat. The absence of a barostat also provides a closed system, allowing the use of the device for mixing and delivering of toxic gases. The prototype of the device has been used to prepare mixtures of different gases for more than 1 year and has been found to operate consistently and reproducibly. The actual concentrations of O2, CO2, and N2 in gas mixtures (determined by gas chromatography) immediately after mixing were between 2.2 and 6.6% of the desired values in four performance tests. Fluctuations in concentration of gases in mixtures after 9 days of continuous gas delivery was less than 2% in four performance tests. Images PMID:16348449

  15. Gettering of Hydrogen and Methane from a Helium Gas Mixture

    NASA Astrophysics Data System (ADS)

    Cardenas, Rosa E.; Cowgill, Donald F.; Stewart, Kenneth D.

    2015-03-01

    In this study, we developed an approach for accurately quantifying the helium content in a gas mixture also containing hydrogen and methane using commercially available getters. We performed a systematic study to examine how both H2 and CH4 can be removed simultaneously from the mixture using two SAES St 172® getters operating at different temperatures. The remaining He within the gas mixture can then be measured directly using a capacitance manometer. The optimum combination involved operating one getter at 650°C to decompose the methane, and the second at 110°C to remove the hydrogen. This approach eliminated the need to reactivate the getters between measurements, thereby enabling multiple measurements to be made within a short time interval, with accuracy better than 1%. We anticipate that such an approach will be particularly useful for quantifying the He-3 in mixtures that include tritium, tritiated methane, and helium-3. The presence of tritiated methane, generated by tritium activity, often complicates such measurements.

  16. Regional Mapping of Gas Uptake by Blood and Tissue in the Human Lung using Hyperpolarized Xenon-129 MRI

    PubMed Central

    Qing, Kun; Ruppert, Kai; Jiang, Yun; Mata, Jaime F.; Miller, G. Wilson; Shim, Y. Michael; Wang, Chengbo; Ruset, Iulian C.; Hersman, F. William; Altes, Talissa A.; Mugler, John P.

    2013-01-01

    Purpose To develop a breath-hold acquisition for regional mapping of ventilation and the fractions of hyperpolarized xenon-129 (Xe129) dissolved in tissue (lung parenchyma and plasma) and red blood cells (RBCs), and to perform an exploratory study to characterize data obtained in human subjects. Materials and Methods A three-dimensional, multi-echo, radial-trajectory pulse sequence was developed to obtain ventilation (gaseous Xe129), tissue and RBC images in healthy subjects, smokers and asthmatics. Signal ratios (total dissolved Xe129 to gas, tissue-to-gas, RBC-to-gas and RBC-to-tissue) were calculated from the images for quantitative comparison. Results Healthy subjects demonstrated generally uniform values within coronal slices, and a gradient in values along the anterior-to-posterior direction. In contrast, images and associated ratio maps in smokers and asthmatics were generally heterogeneous and exhibited values mostly lower than those in healthy subjects. Whole-lung values of total dissolved Xe129 to gas, tissue-to-gas, and RBC-to-gas ratios in healthy subjects were significantly larger than those in diseased subjects. Conclusion Regional maps of tissue and RBC fractions of dissolved Xe129 were obtained from a short breath-hold acquisition, well tolerated by healthy volunteers and subjects with obstructive lung disease. Marked differences were observed in spatial distributions and overall amounts of Xe129 dissolved in tissue and RBCs among healthy subjects, smokers and asthmatics. PMID:23681559

  17. Lattice Boltzmann model for thermal binary-mixture gas flows.

    PubMed

    Kang, Jinfen; Prasianakis, Nikolaos I; Mantzaras, John

    2013-05-01

    A lattice Boltzmann model for thermal gas mixtures is derived. The kinetic model is designed in a way that combines properties of two previous literature models, namely, (a) a single-component thermal model and (b) a multicomponent isothermal model. A comprehensive platform for the study of various practical systems involving multicomponent mixture flows with large temperature differences is constructed. The governing thermohydrodynamic equations include the mass, momentum, energy conservation equations, and the multicomponent diffusion equation. The present model is able to simulate mixtures with adjustable Prandtl and Schmidt numbers. Validation in several flow configurations with temperature and species concentration ratios up to nine is presented. PMID:23767654

  18. Explosions of Hydrogen Gas, Oxygen Gas, and Mixture of Hydrogen and Oxygen Gases with Labels

    NSDL National Science Digital Library

    Dr. Charles Ward

    This video depicts the explosions of pure hydrogen gas, pure oxygen gas, and a mixture of hydrogen and oxygen gases. Balloons were filled with each gas and ignited with a match. Each sample is labeled with the gas or gases involved.

  19. The thermomagnetic torque in nitrogen helium gas mixtures 

    E-print Network

    Aschenbeck, Walter Balamy

    1977-01-01

    -helium gas mixtures at 298K + 5K. By adding helium to the nitrogen gas, the non-spherical non-spherical particle interaction producing the TNT is combined with a non-spherical spherical particle interaction that also gives a contribution to the measured... TNT. The non-spherical spherical particle interaction was studied by varying the helium concentration in the mixture and measuring the change in the charac- teristic maximum magnetic field-pressure ratio, (-H) and the p max maximum torque t mes...

  20. Characterization of Nuclear Recoils in High Pressure Xenon Gas: Towards a Simultaneous Search for WIMP Dark Matter and Neutrinoless Double Beta Decay

    NASA Astrophysics Data System (ADS)

    Renner, J.; Gehman, V. M.; Goldschmidt, A.; Oliveira, C. A. B.; Nygren, D.

    Xenon has recently been the medium of choice in several large scale detectors searching for WIMP dark matter and neutrinoless double beta decay. Though present-day large scale experiments use liquid xenon, the gas phase o_ers advantages favorable to both types of searches such as improved intrinsic energy resolution and fewer fluctuations in the partition of deposited energy between scintillation and ionization channels. We recently constructed a high pressure xenon gas TPC as a prototype for the NEXT (Neutrino Experiment with a Xenon TPC) neutrinoless double beta decay experiment and have demonstrated the feasibility of 0.5% FWHM energy resolution at the 136Xe double beta Q-value with 3-D tracking capabilities. We now present results from this prototype on the simultaneous observation of scintillation and ionization produced by nuclear recoils at approximately 14 bar pressure. The recoils were produced by neutrons of approximately 2-6 MeV emitted from a radioisotope plutonium-beryllium source, and primary scintillation (S1) and electroluminescent photons produced by ionization (S2) were observed. We discuss the potential of gaseous xenon to distinguish between electron and nuclear recoils through the ratio of these two signals S2/S1. From these results combined with the possibility of using columnar recombination to sense nuclear recoil directionality at high pressures we envision a dual-purpose, ton-scale gaseous xenon detector capable of a combined search for WIMP dark matter and neutrinoless double beta decay. This work has been performed within the context of the NEXT collaboration.

  1. Cooling effect of hydrogen negative ions in argon gas mixture

    Microsoft Academic Search

    M. Nishiura; M. Sasao; Y. Matsumoto; M. Hamabe; M. Wada; H. Yamaoka; M. Bacal

    2002-01-01

    The gas mixture effect upon the negative ion temperature in negative ion sources has been studied by the laser photodetachment technique. The ion source is operated at hydrogen pressure from 0.05 to 2.0 Pa. Then argon gas is added up to 100% of the hydrogen pressure. Maximum enhancement of the negative ion density is observed at around a 20%-40% argon

  2. Collisional radiative recombination in high-pressure noble gas mixtures

    NASA Technical Reports Server (NTRS)

    Whitten, B. L.; Downes, L. W.; Wells, W. E.

    1981-01-01

    Rate coefficients are calculated for neutral-assisted collisional radiative recombination in dense, weakly ionized rare-gas mixtures using the quasiequilibrium model developed by Bates. It is shown that the recombination rate can be significantly altered by the presence of a buffer gas. In particular, the presence of helium can enhance the collisional radiative recombination rate coefficient of heavy rare gases by a factor of 5.

  3. Prediction of cost optimal gas feed mixtures for carburization

    Microsoft Academic Search

    D. D. DiDonato; J. S. Kirkaldy

    1986-01-01

    A program is presented which predicts the cost optimal input gas mixture required in a carburization process to achieve a\\u000a desired carbon potential within the furnace atmosphere. The input gas blend used for this process is methane, propane, nitrogen\\u000a and air, although the program may be easily modified for other common blends. The process has no endothermic generator, the\\u000a input

  4. 1D fluid simulations of a helium-xenon filled AC plasma display panel

    Microsoft Academic Search

    R. Veerasingam; R. B. Campbell; R. T. McGrath

    1995-01-01

    A one dimensional multi-species fluid model has been developed to analyze the operation of an ac plasma display panel (AC PDP) that is filled with a helium-xenon Penning mixture. The AC PDP is a promising candidate in the flat panel display industry especially for information displays having large screen areas. A PDP consists of a matrix of gas cells operating

  5. Metastability-exchange and depolarising collisions in xenon and krypton

    Microsoft Academic Search

    V. Lefevre-Seguin; M. Leduc

    1977-01-01

    Collisions between rare-gas atoms in the 3P2 metastable state and in the ground state were studied. The metastable atoms were created by a discharge and oriented by optical pumping, and pressure broadening of their magnetic-resonance curves was measured. For xenon, mixtures of even and odd isotopes were used, leading to a determination of the cross section for metastability-exchange collisions. For

  6. Internal combustion engines fueled by natural gas—hydrogen mixtures

    Microsoft Academic Search

    S. Orhan Akansu; Zafer Dulger; Nafiz Kahraman; T. Nejat Veziro?lu

    2004-01-01

    In this study, a survey of research papers on utilization of natural gas–hydrogen mixtures in internal combustion engines is carried out. In general, HC, CO2, and CO emissions decrease with increasing H2, but NOx emissions generally increase. If a catalytic converter is used, NOx emission values can be decreased to extremely low levels. Consequently, equivalence zero emission vehicles (EZEV) standards

  7. Pulsed-Field-Gradient Measurements of Time-Dependent Gas Diffusion

    Microsoft Academic Search

    Ross W. Mair; David G. Cory; Sharon Peled; Ching-Hua Tseng; Samuel Patz; Ronald L. Walsworth

    1998-01-01

    Pulsed-field-gradient NMR techniques are demonstrated for measurements of time-dependent gas diffusion. The standard PGSE technique and variants, applied to a free gas mixture of thermally polarized xenon and O2, are found to provide a reproducible measure of the xenon diffusion coefficient (5.71 × 10?6m2s?1for 1 atm of pure xenon), in excellent agreement with previous, non-NMR measurements. The utility of pulsed-field-gradient

  8. Optical pumping and xenon NMR

    SciTech Connect

    Raftery, M.D.

    1991-11-01

    Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping {sup 129}Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the {sup 131}Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

  9. Optical pumping and xenon NMR

    SciTech Connect

    Raftery, M.D.

    1991-11-01

    Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping [sup 129]Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the [sup 131]Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

  10. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2001 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure that is placed inside a pressure canister. A similar canister holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD. This is a detail view of MSFC 0100143.

  11. Gas adsorption and gas mixture separations using mixed-ligand MOF material

    DOEpatents

    Hupp, Joseph T. (Northfield, IL); Mulfort, Karen L. (Chicago, IL); Snurr, Randall Q. (Evanston, IL); Bae, Youn-Sang (Evanston, IL)

    2011-01-04

    A method of separating a mixture of carbon dioxiode and hydrocarbon gas using a mixed-ligand, metal-organic framework (MOF) material having metal ions coordinated to carboxylate ligands and pyridyl ligands.

  12. Preparation of neutron-activated xenon for liquid xenon detector calibration

    Microsoft Academic Search

    K. Ni; R. Hasty; T. M. Wongjirad; L. Kastens; A. Manzur; D. N. McKinsey

    2007-01-01

    We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a 5-day activation of natural xenon gas with a 252Cf (4×105n\\/s) source, the activities of two gamma ray lines

  13. Tortuosity Measurement and the Effects of Finite Pulse Widths on Xenon Gas Diffusion NMR Studies of Porous Media

    E-print Network

    R. W. Mair; M. D. Hurlimann; P. N. Sen; L. M. Schwartz; S. Patz; R. L. Walsworth

    2002-11-10

    We have extended the utility of NMR as a technique to probe porous media structure over length scales of ~ 100 - 2000 micron by using the spin 1/2 noble gas 129Xe imbibed into the system's pore space. Such length scales are much greater than can be probed with NMR diffusion studies of water-saturated porous media. We utilized Pulsed Gradient Spin Echo NMR measurements of the time-dependent diffusion coefficient, D(t) of the xenon gas filling the pore space to study further the measurements of both the surface area-pore volume ratio, S/Vp, and the tortuosity (pore connectivity) of the medium. In uniform-size glass bead packs, we observed D(t) decreasing with increasing t, reaching an observed asymptote of ~ 0.62 - 0.65D0, that could be measured over diffusion distances extending over multiple bead diameters. Measurements of D(t)/D0 at differing gas pressures showed this tortuosity limit was not affected by changing the characteristic diffusion length of the spins during the diffusion encoding gradient pulse. This was not the case at the short time limit, where D(t)/D0 was noticeably affected by the gas pressure in the sample. Increasing the gas pressure, and hence reducing D0 and the diffusion during the gradient pulse served to reduce the previously observed deviation of D(t)/D0 from the S/Vp relation. The Pade approximation is used to interpolate between the long and short time limits in D(t). While the short time D(t) point lay above the interpolation line in the case of small beads, due to diffusion during the gradient pulse on the order of the pore size, it was also noted that the experimental D(t) data fell below the Pade line in the case of large beads, most likely due to finite size effects.

  14. Numerical studies of hypersonic binary gas-mixture flows near a sphere

    E-print Network

    Riabov, Vladimir V.

    Numerical studies of hypersonic binary gas-mixture flows near a sphere V.V. Riabov 1 Diffusive] to study the flow. In the present study, diffusive effects in hypersonic flows of binary gas-mixtures near

  15. Gettering of hydrogen and methane from a helium gas mixture

    SciTech Connect

    Cárdenas, Rosa Elia, E-mail: recarde1@uiwtx.edu [Department of Physics, The University of the Incarnate Word, 4301 Broadway, San Antonio, Texas 78209 (United States); Stewart, Kenneth D.; Cowgill, Donald F., E-mail: dfcowgi@sandia.gov [Sandia National Laboratories, Hydrogen and Metallurgical Sciences, 7011 East Avenue, Livermore, California 94550 (United States)

    2014-11-01

    In this study, the authors developed an approach for accurately quantifying the helium content in a gas mixture also containing hydrogen and methane using commercially available getters. The authors performed a systematic study to examine how both H{sub 2} and CH{sub 4} can be removed simultaneously from the mixture using two SAES St 172{sup ®} getters operating at different temperatures. The remaining He within the gas mixture can then be measured directly using a capacitance manometer. The optimum combination involved operating one getter at 650?°C to decompose the methane, and the second at 110?°C to remove the hydrogen. This approach eliminated the need to reactivate the getters between measurements, thereby enabling multiple measurements to be made within a short time interval, with accuracy better than 1%. The authors anticipate that such an approach will be particularly useful for quantifying the He-3 in mixtures that include tritium, tritiated methane, and helium-3. The presence of tritiated methane, generated by tritium activity, often complicates such measurements.

  16. Plasma polymerization of an ethylene-nitrogen gas mixture

    NASA Technical Reports Server (NTRS)

    Hudis, M.; Wydeven, T.

    1975-01-01

    A procedure has been developed whereby nitrogen can be incorporated into an organic film from an ethylene-nitrogen gas mixture using an internal electrode capacitively coupled radio frequency reactor. The presence of nitrogen has been shown directly by infrared transmittance spectra and electron spectroscopic chemical analysis data, and further indirect evidence was provided by dielectric measurements and by the reverse osmosis properties of the film. Preparation of a nitrogen containing film did not require vapor from an organic nitrogen containing liquid monomer. Some control over the bonding and stoichiometry of the polymer film was provided by the added degree of freedom of the nitrogen partial pressure in the gas mixture. This new parameter strongly affected the dielectric properties of the plasma polymerized film and could affect the reverse osmosis behavior.

  17. Composition dependence of ion-transport coefficients in gas mixtures

    NASA Technical Reports Server (NTRS)

    Whealton, J. H.; Mason, E. A.; Robson, R. E.

    1974-01-01

    Simple momentum-transfer theory for the composition dependence of ion mobilities and diffusion coefficients in gas mixtures at arbitrary field strengths is corrected and extended, and compared with a similar theory based on momentum and energy transfer, and with results based on direct solution of the Boltzmann equation by Kihara's method. Final equations are recommended for predicting composition dependences, given only results on ion mobilities and diffusion coefficients in the pure component gases.

  18. Composition dependence of ion transport coefficients in gas mixtures

    NASA Technical Reports Server (NTRS)

    Whealton, J. H.; Mason, E. A.; Robson, R. E.

    1973-01-01

    A simple momentum-transfer theory for the composition dependence of ion mobilities and diffusion coefficients in gas mixtures at arbitrary field strengths is corrected, extended, and compared with a similar theory based on momentum and energy transfer, and with results based on direct solution of the Boltzmann equation by Kihara's method. Final equations are recommended for predicting composition dependences, given only results on ion mobilities and diffusion coefficients in the pure component gases.

  19. Radiation trapping in sodium-noble-gas mixtures

    Microsoft Academic Search

    J. Huennekens; H. J. Park; T. Colbert; S. C. McClain

    1987-01-01

    We have studied sodium resonance radiation under conditions of severe radiation trapping in sodium-argon mixtures, and we report measured values of the effective radiative decay rates. The measured values are compared with values calculated from the Holstein theory of radiation trapping in the impact-regime, foreign-gas pressure-broadening limit. The experiment was designed to satisfy all of the validity criteria imposed by

  20. Gas Mixtures and Ozone Production in an Electrical Discharge

    Microsoft Academic Search

    Thomas J. Manning; Jerry Hedden

    2001-01-01

    The quantitative production of ozone (O3) with N2, O2, and Ar gas mixtures in an atmospheric pressure corona discharge (CD) is investigated. A five-part model is presented that explores the discharge conditions needed for optimum ozone production. One part of the model is the well-known relationship that correlates the discharge's voltage, frequency, gap, dielectric material, etc with the generator's yield.

  1. Critical Viscosity of Xenon investigators

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Dr. Dr. Robert F. Berg (right), principal investigator and Dr. Micheal R. Moldover (left), co-investigator, for the Critical Viscosity of Xenon (CVX/CVX-2) experiment. They are with the National Institutes of Standards and Technology, Gaithersburg, MD. The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Although it does not easily combine with other chemicals, its viscosity at the critical point can be used as a model for a range of chemicals.

  2. Permeation of binary gas mixtures in ultramicroporous membranes.

    PubMed

    da Costa, J C; Lu, G Q; Rudolph, V

    2004-03-01

    High-quality nanometer thick ultramicroporous membranes were prepared from silica sol-gel processes and tested for the permeation of binary gas mixtures of He, H2, CO2, and CH4 across different temperature and partial pressure regimens. Pore size distribution by molecular probing showed that the majority of pore sizes had dimensions below 2.9 A. In 50:50 binary mixtures, the fluxes of gases increased as a function of temperature, indicating an activated transport mechanism. The ultramicroporous membranes showed high selectivities at 150 degrees C for He/CO2 (30), He/CH4 (93), H2/CO2 (10), and H2/CH4 (9) with lower selectivities for CO2/CH4 (5). High activation energies (Ea) were observed for the permeance of 50:50 binary mixtures containing He and H2 of 22.1-27.5 and 17.6-23.1 kJ.mol-1, respectively. The Ea for the permeance of the total mixture approached the Ea for the permeance of the molecule with the smaller kinetic diameter (He or H2). PMID:15233087

  3. Remote sensing of high temperature H2O CO2 CO mixture with a correlated k-distribution fictitious gas method and the single-mixture gas assumption

    NASA Astrophysics Data System (ADS)

    Caliot, C.; Le Maoult, Y.; El Hafi, M.; Flamant, G.

    2006-11-01

    Infrared spectra of high temperature H2O CO2 CO mixtures are calculated using narrow band models in order to simulate hot jet signature at long distance. The correlated k-distribution with fictitious gas (CKFG) approach generally gives accurate data in such situations (especially for long atmospheric paths) but results in long computation time in cases involving mixtures of gases. This time may be reduced if the mixture is treated as a single gas (single-mixture gas assumption, SMG). Thus the lines of the single-mixture gas are assigned to the fictitious gases. In this study, the accuracy of two narrow band models is evaluated. The first narrow band model considers one single-mixture gas and no fictitious gas (CK-SMG) whereas the second model accounts for one single-mixture gas and three fictitious gases (CKFG-SMG). Both narrow band models are compared with reference spectra calculated with a line-by-line (LBL) approach. As expected, the narrow band accuracy is improved by the fictitious gas (FG) assumption particularly when long atmospheric paths are involved. Concerning the SMG assumption, it may lead to an underestimation of about 10% depending on the variation of the gas mixture composition ratio. Nevertheless, in most of realistic situations the SMG assumption results in negligible errors and may be used for remote sensing of plume signature.

  4. NMR studies of laser-polarized xenon gas flow in porous and granular media

    Microsoft Academic Search

    R. W. Mair; M. S. Rosen; R. L. Walsworth; R. Wang; D. G. Cory; D. Candela

    2003-01-01

    NMR techniques that are commonly used to measure diffusion can also be used to measure fluid velocity and\\/or acceleration. In recent years, laser-polarized noble gas NMR has developed into a powerful tool for spin density and diffusion imaging; however few attempts have been made to study gas flow by NMR. We report initial NMR velocity measurements of continuously flowing laser-polarized

  5. Slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures

    DOEpatents

    Aines, Roger D.; Bourcier, William L.; Viani, Brian

    2013-01-29

    A slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures includes the steps of dissolving the gas mixture and carbon dioxide in water providing a gas, carbon dioxide, water mixture; adding a porous solid media to the gas, carbon dioxide, water mixture forming a slurry of gas, carbon dioxide, water, and porous solid media; heating the slurry of gas, carbon dioxide, water, and porous solid media producing steam; and cooling the steam to produce purified water and carbon dioxide.

  6. Heavy Noble Gas Systematics of the Rochambeau Rift Plume: Towards Understanding the Xenon record of early Earth heterogeneities Maria Kocsisn Pet 1, Sujoy Mukhopadhyay 1, Katherine A. Kelley 2

    E-print Network

    Mukhopadhyay, Sujoy

    Heavy Noble Gas Systematics of the Rochambeau Rift Plume: Towards Understanding the Xenon record in isotopic composition and relative noble gas abundances between the MORB source and OIB sources do exist and have been recently characterized to high precision [1]. Here, we present new noble gas data (Ne, Ar, Xe

  7. Chemical discrimination in turbulent gas mixtures with MOX sensors validated by gas chromatography-mass spectrometry.

    PubMed

    Fonollosa, Jordi; Rodríguez-Luján, Irene; Trincavelli, Marco; Vergara, Alexander; Huerta, Ramón

    2014-01-01

    Chemical detection systems based on chemo-resistive sensors usually include a gas chamber to control the sample air flow and to minimize turbulence. However, such a kind of experimental setup does not reproduce the gas concentration fluctuations observed in natural environments and destroys the spatio-temporal information contained in gas plumes. Aiming at reproducing more realistic environments, we utilize a wind tunnel with two independent gas sources that get naturally mixed along a turbulent flow. For the first time, chemo-resistive gas sensors are exposed to dynamic gas mixtures generated with several concentration levels at the sources. Moreover, the ground truth of gas concentrations at the sensor location was estimated by means of gas chromatography-mass spectrometry. We used a support vector machine as a tool to show that chemo-resistive transduction can be utilized to reliably identify chemical components in dynamic turbulent mixtures, as long as sufficient gas concentration coverage is used. We show that in open sampling systems, training the classifiers only on high concentrations of gases produces less effective classification and that it is important to calibrate the classification method with data at low gas concentrations to achieve optimal performance. PMID:25325339

  8. [Separation of carbon dioxide from gas mixture by membrane contactor].

    PubMed

    Zhu, Baoku; Chen, Wei; Wang, Jianli; Xu, Youyi; Xu, Zhikang

    2003-09-01

    In this paper, membrane contactor made of hydrophobic hollow fiber polypropylene porous membrane (HFPPM) was used for separating carbon dioxide (CO2) from CO2/N2 mixtures. The effects of absorbents, concentration and flow rate of feeding gas and absorbent solution, lumen/shell side processes and gas permeability of HFPPM(P) on the CO2 absorption efficiency were investigated. It was found that the absorption efficiency of three absorbents ranged in order of ethanolamine > sodium hydroxide > diethanol amine. For CO2/N2 mixture of c(in) = 20% and v(in) = 0.5-1.0 m3.h-1, and MEA solution of cMEA = 2.5 mol.L-1 and vL = 40-160 L.h-1, the removal efficiencies of CO2 (eta) and the mass transport coefficients (K) was 9.5% - 99.5% and 4.5-6.8 x 10(-4) m.s.-1 respectively. K of the modules made of HFPPM with larger P was relatively larger. eta in lumen process was 30% larger than that in shell process. PMID:14719257

  9. Measurement of Gas Mixture Adsorption Equilibria of Natural Gas Compounds on Microporous Sorbents

    Microsoft Academic Search

    J. U. Keller; F. Dreisbach; H. Rave; R. Staudt; M. Tomalla

    1999-01-01

    Physisorption equilibria of multicomponent gases on microporous solids like zeolites or activated carbons are considered. In view of lack of reliable and simple methods to calculate mixture adsorption isotherms from pure component data, experiments are still indispensable. An overview of classical and new methods to measure multicomponent gas adsorption equilibria is given. Some of the basic concepts like the Gibbs

  10. Characteristics of various tissue and A150-plastic equivalent gas mixtures for microdosimetric applications

    Microsoft Academic Search

    P. M. Jr. DeLuca; M. C. Schell; D. W. Pearson; F. H. Attix

    1982-01-01

    The relative gas gain, alpha particle resolution and gain stability of two A150-plastic equivalent gas mixtures (A150 Mix-1 and A150 Mix-5) as well as propane and methane based tissue equivalent mixtures were measured with a spherical A150-plastic-walled proportional counter. The event-size distribution in a 14.8-MeV neutron field was determined for each gas mixture. Absolute tissue doses deduced from these measurements

  11. Production of Samples of Individual Radioxenon Isotopes Through Neutron Irradiation of Stable Xenon Gas

    SciTech Connect

    Haas, Derek A.; Biegalski, Steven R.; Foltz Biegalski, Kendra M.

    2008-09-23

    The Spectral Deconvolution Analysis Tool (SDAT) software was developed to improve counting statistics and detection limits for nuclear explosion radionuclide measurements. SDAT utilizes spectral deconvolution spectroscopy techniques and can analyze both ?-? coincidence spectra for radioxenon isotopes and high-resolution HPGe spectra from aerosol monitors. The deconvolution algorithm of the SDAT requires a library of ?-? coincidence spectra of individual radioxenon isotopes to determine isotopic ratios in a sample. In order to get experimentally produced spectra of the individual isotopes we have irradiated enriched samples of 130Xe, 132Xe, and 134Xe gas with a neutron beam from the TRIGA reactor at The University of Texas. The samples produced were counted in an Automated Radioxenon Sampler/Analyzer (ARSA) style ?-? coincidence detector. The spectra produced show that this method of radioxenon production yields samples with very high purity of the individual isotopes for 131mXe and 135Xe and a sample with a substantial 133mXe to 133Xe ratio.

  12. Barium Tagging for nEXO in Liquid and Gas Xenon

    NASA Astrophysics Data System (ADS)

    Kravitz, Scott; Brunner, Thomas; Fudenberg, Dan; nEXO Collaboration

    2015-04-01

    nEXO is a next-generation multi-ton experiment currently under development to search for neutrinoless double-beta decay of Xe-136. A positive observation will determine the neutrino to be a Majorana particle. In order to greatly reduce backgrounds for this search, the nEXO collaboration is developing several techniques to recover and identify the decay daughter, Ba-136 (``barium tagging''). This technique may be available for a second phase of the nEXO detector and will improve the sensitivity to probe the neutrino mass scale beyond the inverted hierarchy. A setup to demonstrate Ba ion capture on a probe and subsequent identification through resonance ionization spectroscopy has been developed, and is being used to investigate possible probe substrates, including graphene. For a gas phase detector, appropriate for a later stage, a separate apparatus to extract Ba ions using an RF-only funnel has been constructed and demonstrates extraction of ions from high-pressure Xe to vacuum consistent with simulations. We will describe the status of these systems and the present results of this R&D program.

  13. 10 CFR 504.8 - Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying powerplants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...against excessive use of petroleum or natural gas in mixtures-certifying powerplants...against excessive use of petroleum or natural gas in mixtures—certifying powerplants...prohibit the use of petroleum or natural gas in such powerplant in...

  14. 10 CFR 504.8 - Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying powerplants.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...against excessive use of petroleum or natural gas in mixtures-certifying powerplants...against excessive use of petroleum or natural gas in mixtures—certifying powerplants...prohibit the use of petroleum or natural gas in such powerplant in...

  15. 10 CFR 504.8 - Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying powerplants.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...against excessive use of petroleum or natural gas in mixtures-certifying powerplants...against excessive use of petroleum or natural gas in mixtures—certifying powerplants...prohibit the use of petroleum or natural gas in such powerplant in...

  16. 10 CFR 504.8 - Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying powerplants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...against excessive use of petroleum or natural gas in mixtures-certifying powerplants...against excessive use of petroleum or natural gas in mixtures—certifying powerplants...prohibit the use of petroleum or natural gas in such powerplant in...

  17. Multicomponent gas mixture air bearing modeling via lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Tae Kim, Woo; Kim, Dehee; Hari Vemuri, Sesha; Kang, Soo-Choon; Seung Chung, Pil; Jhon, Myung S.

    2011-04-01

    As the demand for ultrahigh recording density increases, development of an integrated head disk interface (HDI) modeling tool, which considers the air bearing and lubricant film morphology simultaneously is of paramount importance. To overcome the shortcomings of the existing models based on the modified Reynolds equation (MRE), the lattice Boltzmann method (LBM) is a natural choice in modeling high Knudsen number (Kn) flows owing to its advantages over conventional methods. The transient and parallel nature makes this LBM an attractive tool for the next generation air bearing design. Although LBM has been successfully applied to single component systems, a multicomponent system analysis has been thwarted because of the complexity in coupling the terms for each component. Previous studies have shown good results in modeling immiscible component mixtures by use of an interparticle potential. In this paper, we extend our LBM model to predict the flow rate of high Kn pressure-driven flows in multicomponent gas mixture air bearings, such as the air-helium system. For accurate modeling of slip conditions near the wall, we adopt our LBM scheme with spatially dependent relaxation times for air bearings in HDIs. To verify the accuracy of our code, we tested our scheme via simple two-dimensional benchmark flows. In the pressure-driven flow of an air-helium mixture, we found that the simple linear combination of pure helium and pure air flow rates, based on helium and air mole fraction, gives considerable error when compared to our LBM calculation. Hybridization with the existing MRE database can be adopted with the procedure reported here to develop the state-of-the-art slider design software.

  18. Experimental Investigation on High-pressure, High-temperature Viscosity of Gas Mixtures 

    E-print Network

    Davani, Ehsan

    2012-02-14

    of pure hydrocarbon gas, such as methane, ethane, propane and n-butane, and provided an organized database. Lee also used a 15 capillary tube viscometer and measured the viscosity of hydrocarbon gas mixtures (methane/propane, methane/butane...

  19. Xenon Fractionation and Archean Hydrogen Escape

    NASA Technical Reports Server (NTRS)

    Zahnle, K. J.

    2015-01-01

    Xenon is the heaviest gas found in significant quantities in natural planetary atmospheres. It would seem the least likely to escape. Yet there is more evidence for xenon escape from Earth than for any element other than helium and perhaps neon. The most straightforward evidence is that most of the radiogenic Xe from the decay of (129)I (half-life 15.7 Myr) and (244)Pu (half-life 81 Myr) that is Earth's birthright is missing. The missing xenon is often attributed to the impact erosion of early atmospheres of Earth and its ancestors. It is obvious that if most of the radiogenic xenon were driven off by impacts, most of the rest of the atmophiles fared the same fate. The other line of evidence is in the nonradiogenic isotopes of xenon and its silent partner, krypton. Atmospheric xenon is strongly mass fractionated (at about 4% per amu) compared to any known solar system source (Figure 1). This is in stark contrast to krypton, which may not be fractionated at all: atmospheric Kr is slightly heavier than solar Kr (at about 0.5% per amu), but it is the same as in carbonaceous chondrites. Nonradiogenic xenon is also under abundant relative to krypton (the so-called "missing xenon" problem). Together these observations imply that xenon has been subject to fractionating escape and krypton not.

  20. Inviscid behaviour of fines-rich pyroclastic flows inferred from experiments on gas–particle mixtures

    Microsoft Academic Search

    O. Roche; M. A. Gilbertson; J. C. Phillips; R. S. J. Sparks

    2005-01-01

    Experiments were carried out on granular flows generated by instantaneous release of gas-fluidised, bidisperse mixtures and propagating into a horizontal channel. The mixture consists of fine (<100 ?m) and coarse (>100 ?m) particles of same density, with corresponding grain size ratios of ?2 to 9. Initial fluidisation of the mixture destroys the interparticle frictional contacts, and the flow behaviour then

  1. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...503.13 of these regulations. (c) Solar mixtures. OFE will grant a permanent mixtures exemption for the use of a mixture of solar energy (including wind, tide, and other...petroleum or natural gas, where: (1) Solar energy will account for at least 20...

  2. Direct WIMP searches with XENON100 and XENON1T

    NASA Astrophysics Data System (ADS)

    Alfredo Davide, Ferella

    2015-05-01

    The XENON100 experiment is the second phase of the XENON direct Dark Matter search program. It consists of an ultra-low background double phase (liquid-gas) xenon filled time projection chamber with a total mass of 161 kg (62 in the target region and 99 in the active shield), installed at the Laboratori Nazionali del Gran Sasso (LNGS). Here the results from the 224.6 live days of data taken between March 2011 and April 2012 are reported. The experiment set one of the most stringent limits on the WIMP-nucleon spin-independent cross section to date (2 × 10-45 cm2 for a 55 Gev/c2 WIMP mass at 90 % confidence level) and the most stringent on the spin-dependent WIMP-neutron interaction (3.5 × 10-40 for a 45 GeV/c2 WIMP mass). With the same dataset, XENON100 excludes also solar axion coupling to electrons at gAe > 7.7 × 10-12 for a mass of mAxion <1 keV/c2 and galactic axion couplings by gAe > 1 × 10-12 at a mass range of mAxion = 5-10 keV/c2 (both 90 % C.L.). Moreover an absolute spectral comparison between simulated and measured nuclear recoil distributions of light and charge signals from a 241AmBe source demonstrates a high level of detector and systematics understanding. Finally, the third generation of the XENON experiments, XENON1T, is the first tonne scale direct WIMP search experiment currently under construction. The commissioning phase of XENON1T is expected to start in early 2015 followed, a few months after, by the first science run. The experiment will reach sensitivities on the WIMP-nucleon spin-independent cross section down to 2 ×10-47 cm2 after two years of data taking.

  3. Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I2 mixtures

    E-print Network

    Kushner, Mark

    Ion-ion neutralization of iodine in radio-frequency inductive discharges of Xe and I2 mixtures Paul. We found that in time modulated discharges, the emissions from excited states of atomic iodine decays sources using a xenon/iodine gas mixture are being investigated as a multiwavelength UV lighting source

  4. Aerobic fitness in patients with fibrositis. A controlled study of respiratory gas exchange and 133xenon clearance from exercising muscle.

    PubMed

    Bennett, R M; Clark, S R; Goldberg, L; Nelson, D; Bonafede, R P; Porter, J; Specht, D

    1989-04-01

    Aerobic fitness was evaluated in 25 women with fibrositis, by having them exercise to volitional exhaustion on an electronically braked cycle ergometer. Compared with published standards, greater than 80% of the fibrositis patients were not physically fit, as assessed by maximal oxygen uptake. Compared with matched sedentary controls, fibrositis patients accurately perceived their level of exertion in relation to oxygen consumption and attained a similar level of lactic acidosis, as assessed by their respiratory quotient and ventilatory threshold. Exercising muscle blood flow was estimated by 133xenon clearance in a subgroup of 16 fibrositis patients and compared with that in 16 matched sedentary controls; the fibrositis patients exhibited reduced 133xenon clearance. These results indicate a need to include aerobic fitness as a matched variable in future controlled studies of fibrositis and suggest that the "detraining phenomenon" may be of relevance to the etiopathogenesis of the disease. PMID:2706029

  5. Critical Viscosity of Xenon team

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (left) of the National Institutes of Standards and Technology, Gaithersburg, MD.

  6. Critical Viscosity of Xenon team

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD.

  7. A study on transient and steady state sensor data for identification of individual gas concentrations in their gas mixtures

    Microsoft Academic Search

    Ali Gulbag; Fevzullah Temurtas

    2007-01-01

    In this study, a comparative study was performed for the quantitative identification of individual gas concentrations (trichloroethylene and acetone) in their gas mixtures using transient and steady state sensor responses. For this purpose, three neural network (NN) structures were used. The quartz crystal microbalance (QCM) type sensors were selected as gas sensors. One of the neural networks was used for

  8. [Effect of inert gas xenon on the functional state of nucleated cells of peripheral blood during freezing].

    PubMed

    Laptev, D S; Polezhaeva, T V; Zaitseva, O O; Khudyakov, A N; Utemov, S V; Knyazev, M G; Kostyaev, A A

    2015-01-01

    A new method of preservation of nucleated cells in the electric refrigerator with xenon. After slow freezing and storage is even one day at -80 °C persists for more than 60% leukocytes. Cell membranes are resistant to the vital dye. In 85% of granulocytes stored baseline lysosomal-cationic protein, reduced lipid peroxidation and antioxidant activity. Cryopreservation of biological objects in inert gases is a promising direction in the practice of medicine and can be an alternative to the traditional method using liquid nitrogen. PMID:26027341

  9. Hyperpolarized Xenon for NMR and MRI Applications

    PubMed Central

    Witte, Christopher; Kunth, Martin; Döpfert, Jörg; Rossella, Federica; Schröder, Leif

    2012-01-01

    Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 T generate only a small detectable net-magnetization of the sample at room temperature 1. Hence, most NMR and MRI applications rely on the detection of molecules at relative high concentration (e.g., water for imaging of biological tissue) or require excessive acquisition times. This limits our ability to exploit the very useful molecular specificity of NMR signals for many biochemical and medical applications. However, novel approaches have emerged in the past few years: Manipulation of the detected spin species prior to detection inside the NMR/MRI magnet can dramatically increase the magnetization and therefore allows detection of molecules at much lower concentration 2. Here, we present a method for polarization of a xenon gas mixture (2-5% Xe, 10% N2, He balance) in a compact setup with a ca. 16000-fold signal enhancement. Modern line-narrowed diode lasers allow efficient polarization 7 and immediate use of gas mixture even if the noble gas is not separated from the other components. The SEOP apparatus is explained and determination of the achieved spin polarization is demonstrated for performance control of the method. The hyperpolarized gas can be used for void space imaging, including gas flow imaging or diffusion studies at the interfaces with other materials 8,9. Moreover, the Xe NMR signal is extremely sensitive to its molecular environment 6. This enables the option to use it as an NMR/MRI contrast agent when dissolved in aqueous solution with functionalized molecular hosts that temporarily trap the gas 10,11. Direct detection and high-sensitivity indirect detection of such constructs is demonstrated in both spectroscopic and imaging mode. PMID:22986346

  10. Hyperpolarized xenon for NMR and MRI applications.

    PubMed

    Witte, Christopher; Kunth, Martin; Döpfert, Jörg; Rossella, Federica; Schröder, Leif

    2012-01-01

    Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 T generate only a small detectable net-magnetization of the sample at room temperature (1). Hence, most NMR and MRI applications rely on the detection of molecules at relative high concentration (e.g., water for imaging of biological tissue) or require excessive acquisition times. This limits our ability to exploit the very useful molecular specificity of NMR signals for many biochemical and medical applications. However, novel approaches have emerged in the past few years: Manipulation of the detected spin species prior to detection inside the NMR/MRI magnet can dramatically increase the magnetization and therefore allows detection of molecules at much lower concentration (2). Here, we present a method for polarization of a xenon gas mixture (2-5% Xe, 10% N2, He balance) in a compact setup with a ca. 16000-fold signal enhancement. Modern line-narrowed diode lasers allow efficient polarization (7) and immediate use of gas mixture even if the noble gas is not separated from the other components. The SEOP apparatus is explained and determination of the achieved spin polarization is demonstrated for performance control of the method. The hyperpolarized gas can be used for void space imaging, including gas flow imaging or diffusion studies at the interfaces with other materials (8,9). Moreover, the Xe NMR signal is extremely sensitive to its molecular environment (6). This enables the option to use it as an NMR/MRI contrast agent when dissolved in aqueous solution with functionalized molecular hosts that temporarily trap the gas (10,11). Direct detection and high-sensitivity indirect detection of such constructs is demonstrated in both spectroscopic and imaging mode. PMID:22986346

  11. 10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...against excessive use of petroleum or natural gas in mixtures-electing powerplants...against excessive use of petroleum or natural gas in mixtures—electing powerplants...to use a mixture of petroleum or natural gas and an alternate fuel as...

  12. 10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...against excessive use of petroleum or natural gas in mixtures-electing powerplants...against excessive use of petroleum or natural gas in mixtures—electing powerplants...to use a mixture of petroleum or natural gas and an alternate fuel as...

  13. 10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...against excessive use of petroleum or natural gas in mixtures-electing powerplants...against excessive use of petroleum or natural gas in mixtures—electing powerplants...to use a mixture of petroleum or natural gas and an alternate fuel as...

  14. 10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...against excessive use of petroleum or natural gas in mixtures-electing powerplants...against excessive use of petroleum or natural gas in mixtures—electing powerplants...to use a mixture of petroleum or natural gas and an alternate fuel as...

  15. Pathway to cryogen free production of hyperpolarized Krypton-83 and Xenon-129.

    PubMed

    Six, Joseph S; Hughes-Riley, Theodore; Stupic, Karl F; Pavlovskaya, Galina E; Meersmann, Thomas

    2012-01-01

    Hyperpolarized (hp) (129)Xe and hp (83)Kr for magnetic resonance imaging (MRI) are typically obtained through spin-exchange optical pumping (SEOP) in gas mixtures with dilute concentrations of the respective noble gas. The usage of dilute noble gases mixtures requires cryogenic gas separation after SEOP, a step that makes clinical and preclinical applications of hp (129)Xe MRI cumbersome. For hp (83)Kr MRI, cryogenic concentration is not practical due to depolarization that is caused by quadrupolar relaxation in the condensed phase. In this work, the concept of stopped flow SEOP with concentrated noble gas mixtures at low pressures was explored using a laser with 23.3 W of output power and 0.25 nm linewidth. For (129)Xe SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was equivalent to that arising from 15.5±1.9% spin polarized (129)Xe in pure xenon gas. The production rate of the hp gas mixture, measured at 298 K, was 1.8 cm(3)/min. For hp (83)Kr, the equivalent of 4.4±0.5% spin polarization in pure krypton at a production rate of 2 cm(3)/min was produced. The general dependency of spin polarization upon gas pressure obtained in stopped flow SEOP is reported for various noble gas concentrations. Aspects of SEOP specific to the two noble gas isotopes are discussed and compared with current theoretical opinions. A non-linear pressure broadening of the Rb D(1) transition was observed and taken into account for the qualitative description of the SEOP process. PMID:23209620

  16. Pathway to Cryogen Free Production of Hyperpolarized Krypton-83 and Xenon-129

    PubMed Central

    Six, Joseph S.; Hughes-Riley, Theodore; Stupic, Karl F.; Pavlovskaya, Galina E.; Meersmann, Thomas

    2012-01-01

    Hyperpolarized (hp) 129Xe and hp 83Kr for magnetic resonance imaging (MRI) are typically obtained through spin-exchange optical pumping (SEOP) in gas mixtures with dilute concentrations of the respective noble gas. The usage of dilute noble gases mixtures requires cryogenic gas separation after SEOP, a step that makes clinical and preclinical applications of hp 129Xe MRI cumbersome. For hp 83Kr MRI, cryogenic concentration is not practical due to depolarization that is caused by quadrupolar relaxation in the condensed phase. In this work, the concept of stopped flow SEOP with concentrated noble gas mixtures at low pressures was explored using a laser with 23.3 W of output power and 0.25 nm linewidth. For 129Xe SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was equivalent to that arising from 15.5±1.9% spin polarized 129Xe in pure xenon gas. The production rate of the hp gas mixture, measured at 298 K, was 1.8 cm3/min. For hp 83Kr, the equivalent of 4.4±0.5% spin polarization in pure krypton at a production rate of 2 cm3/min was produced. The general dependency of spin polarization upon gas pressure obtained in stopped flow SEOP is reported for various noble gas concentrations. Aspects of SEOP specific to the two noble gas isotopes are discussed and compared with current theoretical opinions. A non-linear pressure broadening of the Rb D1 transition was observed and taken into account for the qualitative description of the SEOP process. PMID:23209620

  17. Enhanced selective extraction of hexane from hexane/soybean oil mixture using binary gas mixtures of carbon dioxide.

    PubMed

    Eller, Fred J; Taylor, S L; Palmquist, Debra E

    2007-04-18

    Carbon dioxide (CO2) can effectively separate hexane from a mixture of soybean oil (SBO) and hexane with a slight coextraction of SBO. Previous research demonstrated that CO2 entrained with helium significantly reduced SBO solubility in CO2. In this study, CO2 was mixed with three gases (He, N2, or Ar) (0.5-30 vol %) to decrease SBO solubility while attempting to maintain hexane solubility. The binary gas mixtures (at 25 degrees C and 9.31 MPa) were passed through a 25 wt % hexane/SBO mixture inside a 2.5 m fractionation column. Coextracted SBO was inversely proportional to binary gas concentration, whereas residual hexane in the raffinate was proportional to binary gas concentration. The 10% binary mixture of N2 or Ar was the best compromise to obtain both low residual hexane levels (i.e., 26 ppm) and low SBO coextraction (i.e., only 40 mg). This carry-over of SBO represents a 95% reduction in SBO carry-over compared to neat CO2. PMID:17373811

  18. Simple method for predicting viscosity of gas mixtures

    NASA Technical Reports Server (NTRS)

    Brokaw, R. S.

    1970-01-01

    Method is derived from the Chapman-enskog theory which describes viscosities at low-to-moderate pressures. Mixtures of nonpolar gases require the viscosities and molecular weights of the constituents in addition to the mixture composition. Dipole moments, boiling points and liquid boiling point densities are also needed with polar gases.

  19. Gas?Kinetic Temperature of Planar High?Frequency Capacitive Discharge Plasma in N2\\/CO2\\/He Gas Mixtures

    Microsoft Academic Search

    V. V. Azharonok; I. I. Filatova; V. D. Shimanovich; L. N. Orlov

    2001-01-01

    Using methods of emission spectroscopy, we have determined the gas-kinetic temperature fields of planar high-frequency capacitive discharge plasma in N2\\/CO2\\/He gas mixtures depending on the excitation frequency, discharge current, pressure, and chemical composition of the mixture. It is shown that the dominant contribution to the neutral component heating in the center of the discharge chamber is made by the processes

  20. Ion mobilities in Xe/Ne and other rare-gas mixtures

    NASA Astrophysics Data System (ADS)

    Piscitelli, D.; Phelps, A. V.; de Urquijo, J.; Basurto, E.; Pitchford, L. C.

    2003-10-01

    The ion mobility or drift velocity data important for modeling glow discharges in rare gas mixtures are not generally available, nor are the ion-neutral scattering cross sections needed to calculate these data. In this paper we propose a set of cross sections for Xe+ and Ne+ collisions with Xe and Ne atoms. Ion mobilities at 300 K calculated using this cross section set in a Monte Carlo simulation are reported for reduced field strengths, E/N, up to 1500×10-21 V m2, in pure gases and in Xe/Ne mixtures containing 5% and 20% Xe/Ne, which are mixtures of interest for plasma display panels (PDPs). The calculated Xe+ mobilities depend strongly on the mixture composition, but the Ne+ mobility varies only slightly with increasing Xe in the mixture over the range studied here. The mobilities in pure gases compare well with available experimental values, and mobilities in gas mixtures at low E/N compare well with our recent measurements which will be published separately. Results from these calculations of ion mobilities are used to evaluate the predictions of Blanc’s law and of the mixture rule proposed by Mason and Hahn [Phys. Rev. A 5, 438 (1972)] for determining the ion mobilities in mixtures from a knowledge of the mobilities in each of the pure gases. The mixture rule of Mason and Hahn is accurate to better than 10% at high field strengths over a wide range of conditions of interest for modeling PDPs. We conclude that a good estimate of ion mobilities at high E/N in Xe/Ne and other binary rare gas mixtures can be obtained using this mixture rule combined with known values of mobilities in parent gases and with the Langevin form for mobility of rare gas ions ion in other gases. This conclusion is supported by results in Ar/Ne mixtures which are also presented here.

  1. Binary Gas Mixtures of Light Helium to Intensify Laminar Forced Convection in Round Tubes

    NASA Astrophysics Data System (ADS)

    Campo, Antonio; Chikh, Salah; Papari, Mohammad; Mobinipouya, Mahammad

    2007-11-01

    This paper addresses potential heat transfer enhancement of laminar gaseous flows inside tubes with constant wall temperatures. The goal is to investigate the capabilities of certain binary gas mixtures of light helium as the primary gas with nitrogen, oxygen, carbon dioxide, methane, sulfur hexafluoride and tetrafluoromethane as the secondary heavier gases. The velocity of the binary gas mixtures is fully established and the temperature develops from a uniform value. The thermophysical properties of the binary gas mixtures depend on the molar gas composition in the w-domain [0, 1]. The two case studies involve a low mean bulk temperature of 300 K and the other a high mean bulk temperature of 600 K, both sharing 1 atm. The two target parameters for analysis and design are the maximum heat transfer rate and the pressure drop at the optimal molar gas composition.

  2. Method and apparatus for perforating at cutting with a solid fueled gas mixture

    SciTech Connect

    Woytek, A.J.; Lileck, J.T.; Steigerwalt, E.J.

    1984-05-08

    A method for cutting pipe casings and concrete liners or perforating the same and localized portions of surrounding strata in an earth bore is set forth wherein a gas phase cutting or perforating jet mixture of fluorine and nitrogen trifluoride is delivered to the cutting or perforation site from the decomposition of a solid, normally stable, perfluoroammonium salt. An appropriate apparatus for delivering the gas mixture of fluorine and nitrogen trifluoride from the salt is also disclosed.

  3. Transient flow in pipelines of high-pressure hydrogen–natural gas mixtures

    Microsoft Academic Search

    Sami Elaoud; Ezzeddine Hadj-Taïeb

    2008-01-01

    The purpose of this study is the numerical modeling of high-pressure transient flow of hydrogen–natural gas mixtures in rigid pipelines. The governing equations for such flows are two coupled, non-linear, hyperbolic, partial differential equations. The fluid pressure and velocity are considered as two principal dependent variables. The fluid is a homogeneous hydrogen–natural gas mixture for which the density is defined

  4. The determination of compressibility factors of gaseous butane-nitrogen mixtures in the gas phase 

    E-print Network

    Evans, Robert Buckner

    1955-01-01

    THE DETERMINATION OF COMPRESSIBILITY FACTORS OF GASEOUS BUTANE-NITROGEN MIXTURES IN THE GAS PHASE A D issertation By Robert Buckner Evans, III Approved as to style and content by: (Chairman of Committee) (Head of^ 'ent Advisor) June 1955... ?-; i'i i ; A R y ? 'A 'Gi- Or- T EX AS THE DETERMINATION OF COMHIESSIBILITI FACTORS OF GASEOUS BUTANE-NITROGEN MIXTURES IN THE GAS PHASE A D issertation By ROBERT BUCKNER EVANS, III Submitted' to the Graduate School of the Agricultural...

  5. Hydrogen content of cooled uranium hexafluoride-hydrogen fluoride gas mixtures

    Microsoft Academic Search

    W. D. Hedge; C. M. Turner

    1981-01-01

    The knowledge of the hydrogen concentration of hydrogen fluoride (HF)\\/uranium hexafluoride (UFâ) gas mixtures when cooled below condensation or desublimation temperatures is necessary in determining fissile moderation for criticality safety considerations in UFâ desublimation processes. The HF\\/UFâ gas mixtures used in this study were initially at 126°F (52°C) and a maximum of 607 torr before cooling to 60°F, 46°F, 32°F,

  6. Manifestations of collisions in the laser SRS - CARS diagnostics of hydrogen in rarefied gas mixtures

    SciTech Connect

    Mikheev, Gen M; Mogileva, T N; Kalyuzhnyi, D G [Institute of Applied Mechanics, Ural Division of the Russian Academy of Sciences, Izhevsk (Russian Federation); Mikheev, Geor M ['Chuvashenergo' Joint Stock Co., Cheboksary (Russian Federation)

    2002-01-31

    CARS diagnostics of hydrogen in rarefied gas mixtures is performed using the biharmonic laser pump based on the SRS by the vibrational hydrogen transition. The diagnostics is shown to be substantially affected by collisions, which result in variations in the linewidth and the frequency of the Raman-active transition. This influence is distinctly observed at pressures higher than 0.05 atm and depends on the composition of the buffer gas mixture. (nonlinear optical phenomena)

  7. The determination of compressibility factors of gaseous butane-nitrogen mixtures in the gas phase

    E-print Network

    Evans, Robert Buckner

    1955-01-01

    THE DETERMINATION OF COMPRESSIBILITY FACTORS OF GASEOUS BUTANE-NITROGEN MIXTURES IN THE GAS PHASE A D issertation By Robert Buckner Evans, III Approved as to style and content by: (Chairman of Committee) (Head of^ 'ent Advisor) June 1955... ?-; i'i i ; A R y ? 'A 'Gi- Or- T EX AS THE DETERMINATION OF COMHIESSIBILITI FACTORS OF GASEOUS BUTANE-NITROGEN MIXTURES IN THE GAS PHASE A D issertation By ROBERT BUCKNER EVANS, III Submitted' to the Graduate School of the Agricultural...

  8. Venus, Earth, Xenon

    NASA Astrophysics Data System (ADS)

    Zahnle, K. J.

    2013-12-01

    Xenon has been regarded as an important goal of many proposed missions to Venus. This talk is intended to explain why. Despite its being the heaviest gas found in natural planetary atmospheres, there is more evidence that Xe escaped from Earth than for any element apart from helium: (i) Atmospheric Xe is very strongly mass fractionated (at about 4% per amu) from any known solar system source. This suggests fractionating escape that preferentially left the heavy Xe isotopes behind. (ii) Xe is underabundant compared to Kr, a lighter noble gas that is not strongly mass fractionated in air. (iii) Radiogenic Xe is strongly depleted by factors of several to ~100 compared to the quantities expected from radioactive decay of primordial solar system materials. In these respects Xe on Mars is similar to Xe on Earth, but with one key difference: Xe on Mars is readily explained by a simple process like hydrodynamic escape that acts on an initially solar or meteoritic Xe. This is not so for Earth. Earth's Xe cannot be derived by an uncontrived mass fractionating process acting on any known type of Solar System Xe. Earth is a stranger, made from different stuff than any known meteorite or Mars or even the Sun. Who else is in Earth's family? Comets? We know nothing. Father Zeus? Data from Jupiter are good enough to show that jovian Xe is not strongly mass-fractionated but not good enough to determine whether Jupiter resembles the Earth or the Sun. Sister Venus? Noble gas data from Venus are incomplete, with Kr uncertain and Xe unmeasured. Krypton was measured by several instruments on several spacecraft. The reported Kr abundances are discrepant and were once highly controversial. These discrepancies appear to have been not so much resolved as forgotten. Xenon was not detected on Venus. Upper limits were reported for the two most abundant xenon isotopes 129Xe and 132Xe. From the limited data it is not possible to tell whether Venus's affinities lie with the solar wind, or with the chondrites, with Earth, or with none of the above. Modern spacecraft mass spectrometers are at least 100-fold more sensitive to noble gases. Sending such an instrument to Venus may be the last best hope for decrypting what Earth's noble gases have been trying to tell us.

  9. GAS CHROMATOGRAPHIC RETENTION PARAMETERS DATABASE FOR REFRIGERANT MIXTURE COMPOSITION MANAGEMENT

    EPA Science Inventory

    Composition management of mixed refrigerant systems is a challenging problem in the laboratory, manufacturing facilities, and large refrigeration machinery. Ths issue of composition management is especially critical for the maintenance of machinery that utilizes zeotropic mixture...

  10. Decay of metastable xenon atoms Xe*(3P2) in a xenon afterglow

    Microsoft Academic Search

    A. Barbet; N. Sadeghi; J. C. Pebay-Peyroula

    1975-01-01

    Using the light absorption technique, the decay constant for the density of metastable xenon atoms Xe*(3P2) has been measured in a pure xenon afterglow at pressures between 4*10-2 and 8 Torr. At a gas temperature at 300K the diffusion coefficients D0 for the Xe*(3P2) metastable atoms in the parent gas has been found to be 19+or-2 cm2 Torr s-1, the

  11. Measurements of local mixture fraction of reacting mixture in swirl-stabilised natural gas-fuelled burners

    NASA Astrophysics Data System (ADS)

    Orain, M.; Hardalupas, Y.

    2011-11-01

    Local, time-dependent measurements of mixture fraction of the reacting mixture were obtained in a swirl-stabilised natural gas-fuelled, nominally non-premixed burner using the intensity of chemiluminescence from OH? and CH? radicals. The measurements quantified the mean, rms of fluctuations and probability density functions of local mixture fraction at the stabilisation region of the flame. In addition, the probability of flame presence and the degree of lean or rich versus stoichiometric reaction is reported. The burner was operated for three air flow Reynolds numbers (Re=18970, 29100 and 57600), at an overall equivalence ratio of 0.32, without and with imposed oscillations to the air flow of the burner at the resonance frequency of 350 Hz. Results show that combustion occurred in a partially premixed mode for all flow conditions, although fuel and air were injected separately in the reaction zone. The mean local mixture fraction was nearly stoichiometric at the base of the flame without imposed air oscillations, but with large fluctuations leading to around 80% of lean or rich reaction. The degree of non-stoichiometric reaction increased with axial distance from the burner exit and Reynolds number and lean reaction dominated. Imposed air oscillations led to lifted flames and increased the degree of non-stoichiometric reaction for Re=18970 and 29100, whereas the flame remained attached onto the injector for Re=57600 and little modification of the mixture fraction was observed.

  12. Measurements of laminar burning velocities for natural gas-hydrogen-air mixtures

    SciTech Connect

    Huang, Zuohua; Zhang, Yong; Zeng, Ke; Liu, Bing; Wang, Qian; Jiang, Deming [State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an (People's Republic of China)

    2006-07-15

    Laminar flame characteristics of natural gas-hydrogen-air flames were studied in a constant-volume bomb at normal temperature and pressure. Laminar burning velocities and Markstein lengths were obtained at various ratios of hydrogen to natural gas (volume fraction from 0 to 100%) and equivalence ratios (f from 0.6 to 1.4). The influence of stretch rate on flame was also analyzed. The results show that, for lean mixture combustion, the flame radius increases with time but the increasing rate decreases with flame expansion for natural gas and for mixtures with low hydrogen fractions, while at high hydrogen fractions, there exists a linear correlation between flame radius and time. For rich mixture combustion, the flame radius shows a slowly increasing rate at early stages of flame propagation and a quickly increasing rate at late stages of flame propagation for natural gas and for mixtures with low hydrogen fractions, and there also exists a linear correlation between flame radius and time for mixtures with high hydrogen fractions. Combustion at stoichiometric mixture demonstrates the linear relationship between flame radius and time for natural gas-air, hydrogen-air, and natural gas-hydrogen-air flames. Laminar burning velocities increase exponentially with the increase of hydrogen fraction in mixtures, while the Markstein length decreases and flame instability increases with the increase of hydrogen fractions in mixture. For a fixed hydrogen fraction, the Markstein number shows an increase and flame stability increases with the increase of equivalence ratios. Based on the experimental data, a formula for calculating the laminar burning velocities of natural gas-hydrogen-air flames is proposed. (author)

  13. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, Roswell J. (Pittsburgh, PA); Basel, Richard A. (Pittsburgh, PA)

    1996-01-01

    A gas sensor measures O.sub.2 content of a reformable monitored gas containing hydrocarbons H.sub.2 O and/or CO.sub.2, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system.

  14. Investigation of xenon metastable atoms

    Microsoft Academic Search

    Tian Xia; Yuan-Yu Jau; William Happer

    2007-01-01

    The electron configuration of a xenon atom in its metastable state consists of tightly bound core electrons with a single missing electron in the 5P shell, and a loosely bound ``valence electron'' in the 6S shell. For our current work, we have been using pyrex cells with internal tungsten electrodes, filled with isotopically enriched Xe129 gas. Ti-sapphire laser is used

  15. Detailed investigation on the neon-xenon mixture as filling gas for mercury-free fluorescent lamps

    Microsoft Academic Search

    H. Sarroukh; E. Robert; C. Cachoncinlle; R. Viladrosa; G. Pousse; J. M. Pouvesle

    2001-01-01

    Summary form only given. The conventional fluorescent lamp is a low-pressure mercury discharge device with a phosphor coating that converts ultraviolet light into visible light. Since mercury is toxic, it represents an environmental hazard and suggests a need for mercury-free light sources. Many years ago, several investigations were carried out in an endeavour to use inert gases as a substitute

  16. Preliminary performance of the Brayton 4.25 inch radial compressor operating in a helium xenon gas mixture

    NASA Technical Reports Server (NTRS)

    Asadourian, A. S.; Hecker, T. P.; Kruchowy, R.

    1971-01-01

    Compressor performance was mapped during the Brayton cycle power system testing. The range of testing included three shaft speeds: the design speed of 36,000 rpm, 10 percent overspeed (39,600 rpm), and 10 percent underspeed (32,400 rpm). A range of compressor inlet temperatures from 60 F to 120 F and discharge pressures from 20 to 45 psia were included. The effects of turbine inlet temperatures (from 1200 F to 1600 F) on the compressor were also studied. The data presented include plots of weight flow, compressor pressure ratio, efficiency, and temperature-rise ratio.

  17. Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection

    DOEpatents

    Owen, Thomas E.; Miller, Michael A.

    2007-03-13

    A method of determining the amount of nitrogen in a gas mixture. The constituent gases of the mixture are dissociated and transformed to create a substance that may measured using nondispersive infrared adsorption techniques.

  18. Measurement of nitrogen content in a gas mixture by transforming the nitrogen into a substance detectable with nondispersive infrared detection

    DOEpatents

    Owen, Thomas E. (Helotes, TX); Miller, Michael A. (San Antonio, TX)

    2010-08-24

    A method of determining the amount of nitrogen in a gas mixture. The constituent gases of the mixture are dissociated and transformed to create a substance that may measured using nondispersive infrared adsorption techniques.

  19. Numerical simulation of the passive gas mixture flow

    NASA Astrophysics Data System (ADS)

    Kyncl, Martin; Pelant, Jaroslav

    2015-05-01

    We work with the system of equations describing non-stationary compressible turbulent multicomponent flow in the gravitational field, and we focus on the numerical solution of these equations. In these computations we assume the mixture of perfect inert gases. The thermodynamic constants are functions in time and space. The finite volume method is used. In order to solve the local boundary problem at each mesh face, we use the original analysis of the exact solution of the Riemann problem. The roughness of the surface is simulated via the specific dissipation at the wall. We show the computational results obtained with the own-developed code (C,FORTRAN) for the solution of the 3D compressible turbulent mixture flow. The originality of this work lies with the special handling of the boundary conditions, which shows superior behavior, and own computational code.

  20. Standardisation of gas mixtures for estimating carbon monoxide transfer factor

    Microsoft Academic Search

    A H Kendrick; G Laszlo

    1993-01-01

    BACKGROUND--The American Thoracic Society recommends that the inspired concentration used for the estimation of carbon monoxide transfer factor (TLCO) mixture should be 0.25-0.35% carbon monoxide, 10-14% helium, 17-21% oxygen, balance nitrogen. Inspired oxygen influences alveolar oxygen and hence carbon monoxide uptake, such that transfer factor increases by 0.35% per mm Hg decrease in alveolar oxygen. To aid in the standardisation

  1. Laser Cooling of Dense Rubidium-Noble Gas Mixtures via Collisional Redistribution of Radiation

    E-print Network

    Vogl, Ulrich; Weitz, Martin; 10.1117/12.905897

    2012-01-01

    We describe experiments on the laser cooling of both helium-rubidium and argon-rubidium gas mixtures by collisional redistribution of radiation. Frequent alkali-noble gas collisions in the ultradense gas, with typically 200\\,bar of noble buffer gas pressure, shift a highly red detuned optical beam into resonance with a rubidium D-line transition, while spontaneous decay occurs close to the unshifted atomic resonance frequency. The technique allows for the laser cooling of macroscopic ensembles of gas atoms. The use of helium as a buffer gas leads to smaller temperature changes within the gas volume due to the high thermal conductivity of this buffer gas, as compared to the heavier argon noble gas, while the heat transfer within the cell is improved.

  2. M. Bahrami ENSC 461 (S 11) Gas Vapor Mixtures and HVAC 1 Gas Vapor Mixtures and HVAC

    E-print Network

    Bahrami, Majid

    of the mixture. Adiabatic Saturation Process Consider a long insulated channel that contains a pool of water through this channel. If the channel is long enough, the air stream exits as saturated air at temperature air normally contains some water vapor (moisture). The dry-air contains no water. Although the amount

  3. Gravity-induced density and concentration profiles in binary mixtures near gas-liquid critical lines

    NASA Astrophysics Data System (ADS)

    Chang, R. F.; Sengers, J. M. H. Levelt; Doiron, T.; Jones, J.

    1983-09-01

    We have calculated gravity-induced density and concentration gradients using scaled equations of state fashioned after that of Leung and Griffiths for binary mixtures near gas-liquid critical lines. The mixtures considered here are those of helium-3 and helium-4 and of carbon dioxide and ethane. Our calculations show that the density profiles for both mixtures in any proportion of the components are similar to those of pure fluids. The concentration gradients in the helium mixture have the same appearance as the density gradients. In the carbon dioxide-ethane system, however, the form of the concentration profile varies greatly, depending on the overall composition. Moreover, the temperature at which a mixture separates into two phases is slightly different from that expected for the mixture in the absence of gravity. We have also examined the case where a mixture is subjected to a large gravitational field such as can be generated in a centrifuge and found that, although the density gradient in all the mixtures is like that in pure fluids, the concentration gradients in the mixtures of carbon dioxide and ethane have complex features related to the presence of critical azeotropy.

  4. Experimental Characterization and Molecular Study of Natural Gas Mixtures 

    E-print Network

    Cristancho Blanco, Diego Edison

    2011-08-08

    Natural Gas (NG) plays an important role in the energy demand in the United States and throughout the world. Its characteristics as a clean, versatile and a sustainable source of energy makes it an important alternative ...

  5. Steady-state electrode potentials of solid-electrolyte cells in reducing chemically nonequilibrium gas mixtures

    Microsoft Academic Search

    G. I. Fadeev; A. S. Kalyakin; S. I. Somov

    2010-01-01

    The paper studies the steady-state potential response of the electrodes of solid-electrolyte cells with ZrO2 + 9 mol % Y2O3 in reducing nonequilibrium gas mixtures of N2 + H2 + H2O + O2 with a low content of O2 and in the mixtures of CH4 + CO2 + CO with a low content of CO, in the temperature range of

  6. Energy transfer in noble-gas mixtures: Penning ionization in He\\/Xe

    Microsoft Academic Search

    R. Shuker; A. Szoeke; E. Zamir; Y. Binur

    1975-01-01

    Following recent reports on strong uv and ir laser transitions in noble-gas mixtures, we attempted to determine the dominant precursor reactions leading to laser action. In this paper we present experimental results of time-dependent spectroscopy of the various species existing in He\\/Xe mixtures excited by fast transverse electrical discharges. We also present some parametric measurements of the He\\/Xe laser in

  7. Rayleigh-Brillouin Scattering in Binary-Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Gu, Z.; Ubachs, W.; Marques, W.; van de Water, W.

    2015-06-01

    Precise measurements are performed on spectral line shapes of spontaneous Rayleigh-Brillouin scattering in mixtures of the noble gases Ar and Kr, with He. Admixture of a light He atomic fraction results in marked changes of the spectra, although in all experiments He is merely a spectator atom: it affects the relaxation of density fluctuations of the heavy constituent, but its contribution to the scattered light intensity is negligibly small. The results are compared to a theory for the spectral line shape without adjustable parameters, yielding excellent agreement for the case of binary monatomic gases, signifying a step towards modeling and understanding of light scattering in more complex molecular media.

  8. Heat Transfer and Pressure Drop in Concentric Annular Flows of Binary Inert Gas Mixtures

    NASA Technical Reports Server (NTRS)

    Reid, R. S.; Martin, J. J.; Yocum, D. J.; Stewart, E. T.

    2007-01-01

    Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 < r* < 0.83. These smooth tube data may serve as a reference to the heat transfer and pressure drop performance in annuli, tubes, and channels having helixes or spacer ribs, or other surfaces.

  9. Current filamentation in discharge-excited F{sub 2}-based excimer laser gas mixtures

    SciTech Connect

    Mathew, D.; Bastiaens, H.M.J.; Boller, K.-J.; Peters, P.J.M. [Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2006-03-06

    Discharge instabilities in x-ray preionized F{sub 2}-doped excimer laser gas mixtures are investigated using an intensified charge coupled device camera with a gating time of 300 ps. In contradiction with earlier theories and observations, it is found that the discharges in He/F{sub 2} mixtures are homogeneous only at very low concentration of F{sub 2} (0.025%). We present experimental results, which prove that in He/Kr/F{sub 2} mixtures the appearance of discharge filaments is coupled with the presence of F{sub 2} rather than Kr.

  10. Coproduction of durene and gasoline from synthesis gas and alcohols and separation of durene gasoline mixtures

    SciTech Connect

    Fowles, P. E.; Yan, T. Y.

    1985-06-18

    Durene is recovered from a mixture rich in durene and containing hydrocarbons boiling in the gasoline range by cooling the mixture to a point where crystallization occurs and separating the crystallized durene. The durene subsequently is washed with a wash fluid. The wash fluid which can be methanol, is returned to a process wherein it is converted to gasoline and durene. The separated mother liquor is added to the gasoline fraction. The original mixture is obtained by the catalytic conversion of synthesis gas and methanol or by other means.

  11. Observation of Single-File Diffusion in Dipeptide Nanotubes by Xenon-129 High Field NMR Diffusometry

    E-print Network

    Weston, Ken

    Observation of Single-File Diffusion in Dipeptide Nanotubes by Xenon-129 High Field NMR evidence for molecular single file diffusion of xenon gas confined inside model nanotube systems, i.e. L of xenon measured by Xe-129 PFG NMR in dipeptide nanotubes at 298 K. The experimental data in the figure

  12. Mass transfer of helium, neon, argon, and xenon through a steady-state upper mantle

    Microsoft Academic Search

    D. Porcelli; G. J. Wasserburg

    1995-01-01

    We have examined the steady-state upper mantle model for helium, neon, argon, and xenon following the mass transfer approach presented by Kellogg and Wasserburg (1990) for helium and Porcelli and Wasserburg (1995a) for xenon. The model explains the available observational data of mantle helium, neon, argon, and xenon isotope compositions and provides specific predictions regarding the rare gas isotopic compositions

  13. On the behavior of a slightly rarefied gas mixture over plane boundaries

    NASA Astrophysics Data System (ADS)

    Onishi, Y.

    1986-07-01

    The behavior of a slightly rarefied gas mixture bounded by plane boundaries is investigated on the basis of the linearized Boltzmann equation of B-G-K type for gas mixtures under the diffusive boundary condition. A useful result of the present analysis is that the macroscopic equations and the appropriate boundary conditions in terms of slip and jump are obtained together with the Knudsen-layer correlations near the boundaries. This system of equations makes possible the treatment at fluid dynamic level for various problems of gas mixtures with plane geometry which require kinetic theory consideration. As an application of this system, some basic flow problems of a slightly rarefield gas mixture, namely, Couette flow, thermal slip flow and diffusion slip flow between two plates are taken up. The total velocity distributions of these concrete problems are explicitly obtained for the first time, and their dependence on the properties and concentration of the component gases in the mixture are clarified in some detail.

  14. Gas-phase separations of complex tryptic peptide mixtures.

    PubMed

    Taraszka, J A; Counterman, A E; Clemmer, D E

    2001-02-01

    High-resolution ion mobility and time-of-flight mass spectrometry techniques have been used to analyze complex mixtures of peptides generated from tryptic digestion of fourteen common proteins (albumin, bovine, dog, horse, pig, and sheep; aldolase, rabbit; beta-casein, bovine; cytochrome c, horse; beta-lactoglobulin, bovine; myoglobin, horse; hemoglobin, human, pig, rabbit, and sheep). In this approach, ions are separated based on differences in mobilities in helium in a drift tube and on differences in their mass-to-charge ratios in a mass spectrometer. From data recorded for fourteen individual proteins (over a m/z range of 405 to 1,000), we observe 428 peaks, of which 205 are assigned to fragments that are expected from tryptic digestion. In a separate analysis, the fourteen mixtures have been combined and analyzed as one system. In the single dataset, we resolve 260 features and are able to assign 168 peaks to unique peptide sequences. Many other unresolved features are observed. Methods for assigning peptides based on the use of m/z information and existing mobilities or mobilities that are predicted by use of intrinsic size parameters are described. PMID:11293699

  15. High-precision gas gain and energy transfer measurements in Ar-CO2 mixtures

    NASA Astrophysics Data System (ADS)

    ?ahin, Özkan; Kowalski, Tadeusz Z.; Veenhof, Rob

    2014-12-01

    Ar-CO2 is a Penning mixture since a fraction of the energy stored in Ar 3p5 3 d and higher excited states can be transferred to ionize CO2 molecules. In the present work, concentration and pressure dependence of Penning transfer rate and photon feedback parameter in Ar-CO2 mixtures have been investigated with recent systematic high-precision gas gain measurements which cover the range 1-50% CO2 at 400, 800, 1200, 1800 hPa and gas gain from 1 to 5×105.

  16. Variable-temperature cryogenic trap for the separation of gas mixtures

    NASA Technical Reports Server (NTRS)

    Des Marais, D. J.

    1978-01-01

    The paper describes a continuous variable-temperature U-shaped cold trap which can both purify vacuum-line combustion products for subsequent stable isotopic analysis and isolate the methane and ethane constituents of natural gases. The canister containing the trap is submerged in liquid nitrogen, and, as the gas cools, the gas mixture components condense sequentially according to their relative vapor pressures. After the about 12 min required for the bottom of the trap to reach the liquid-nitrogen temperature, passage of electric current through the resistance wire wrapped around the tubing covering the U-trap permits distillation of successive gas components at optimal temperatures. Data on the separation achieved for two mixtures, the first being typical vacuum-line combustion products of geochemical samples such as rocks and the second being natural gas, are presented, and the thermal behavior and power consumption are reported.

  17. Understanding and Designing Field Asymmetric Waveform Ion Mobility Spectrometry Separations in Gas Mixtures

    SciTech Connect

    Shvartsburg, Alexandre A.; Tang, Keqi; Smith, Richard D.

    2004-12-15

    Field Asymmetric waveform Ion Mobility Spectrometry (FAIMS) has significant potential for post-ionization separations in conjunction with MS analyses. FAIMS exploits the fact that ion mobilities in gases depend on the electric field in a manner specific to each ion, which allows one to fractionate ion mixtures. Nearly all previous work has used pure gases, for which FAIMS fundamentals are understood reasonably well. However, experiments in gas mixtures like N2/CO2 have uncovered unexpected phenomena that remained unexplained. Here we introduce a universal model for FAIMS separations in mixtures, derived from the formalisms that determine high-field mobilities in heteromolecular gases. Overall, the theoretical findings are consistent with the data in N2/CO2, though quantitative discrepancies remain. As a control, modeled results for N2/O2 fit Blanc's law, in agreement with measurements. Calculations for He/N2 are broadly consistent with observations, and show why adding He to the working gas enhances FAIMS performance. We predict spectacular non-Blanc effects in mixtures of extremely disparate gases such as He/CO2, which could improve the peak capacity and sensitivity of technique. Understanding the FAIMS operation in gas mixtures will enable rational design of media for both targeted and global analyses.

  18. Understanding and designing field asymmetric waveform ion mobility spectrometry separations in gas mixtures.

    PubMed

    Shvartsburg, Alexandre A; Tang, Keqi; Smith, Richard D

    2004-12-15

    Field asymmetric waveform ion mobility spectrometry (FAIMS) has significant potential for post-ionization separations in conjunction with MS analyses. FAIMS fractionates ion mixtures by exploiting the fact that ion mobilities in gases depend on the electric field in a manner specific to each ion. Nearly all previous work has used pure gases, for which FAIMS fundamentals are understood reasonably well; however, unexpected phenomena observed in some gas mixtures (e.g., N(2)/CO(2)) but not in others (N(2)/O(2)) remain unexplained. Here, we introduce and experimentally test a universal model for FAIMS separations in mixtures, derived from formalisms that determine high-field mobilities in heteromolecular gases. Overall, the theoretical findings are consistent with data for N(2)/CO(2) (although quantitative discrepancies remain), while results for N(2)/O(2) fit Blanc's law, in agreement with measurements. Calculations for He/N(2) and He/CO(2) are also consistent with observations and suggest why adding He to the working gas generally enhances FAIMS performance. As predicted, mixtures of gases with extremely disparate molecular masses and collision cross sections, such as He/SF(6), exhibit spectacular non-Blanc effects, which greatly improve the resolution and peak capacity of technique. Understanding FAIMS operation in gas mixtures is expected to enable the rational design of media for both targeted and global analyses. PMID:15595881

  19. Bulk rotational relaxation time and cross-section in gas mixtures

    Microsoft Academic Search

    M. Terzic; D Markushev; J Jovanovi?-Kurepa

    2001-01-01

    In an earlier paper [M. Terzi?, J. Jovanovi?-Kurepa, D.D. Markušev, J. Phys. B: At. Mol. Opt. Phys. 32 (1999) 1193] we have presented a method for evaluation of the bulk rotational relaxation times and cross-sections in gas mixtures from the measured saturation intensity, IS, vs. buffer gas pressure, pbuff, at constant incident laser energy. According to this method, the bulk

  20. Simulation of Gas-Phase Kinetics in CHF3:H2: O2 Mixtures

    Microsoft Academic Search

    Dmitry G. Voloshin; Konstantin S. Klopovskiy; Yuri A. Mankelevich; Nikolay A. Popov; Tatyana V. Rakhimova; Alexander T. Rakhimov

    2007-01-01

    A gas-phase reaction model for and mixtures was developed. Self-consistent electron impact cross-section set for was introduced. The original total and partial dissociation cross sections were received. A developed gas-phase kinetic scheme was tested on the experimental data. An important role of the chain reactions in the kinetics of F and H atoms and radicals was revealed.

  1. Study of lasing and discharge plasma parameters in noble gas\\/metal atom mixtures

    Microsoft Academic Search

    Tadeusz M. Adamowicz

    2003-01-01

    Results of research on metal ion lasers are presented. They were obtained using novel diagnostic methods for measurements lasing parameters of noble gas-metal vapor systems and determination of metal atom diffusion coefficients in noble gases. Influence of helium 3He isotope on plasma and laser parameters in He-noble gas and metal atom mixtures was studied as well as some elementary processes

  2. Hollow-cathode excitation of ion laser transitions in noble-gas mixtures

    Microsoft Academic Search

    R. Solanki; D. C. Gerstenberger; W. M. Fairbank Jr.; E. L. Latush; G. J. Collins

    1979-01-01

    Excitation of laser transitions in He-Kr, He-Ar, Ne-Xe, and He-Ne-Xe mixtures was investigated in hollow-cathode discharges. The dominant excitation mechanism of the noble-gas ions was found to be collisions of the second kind between the ground-state noble-gas ions and helium or neon metastables. Based on gain and absorption spectroscopy measurements, the cross section for this mechanism was estimated to be

  3. Variational principles and two-fluid hydrodynamics of bubbly liquid\\/gas mixtures

    Microsoft Academic Search

    J. A. Geurst

    1986-01-01

    In a recent paper the two-phase flow equations for a bubbly liquid\\/gas mixture were derived by variational methods. Starting point was an Euler form of Hamilton's extended principle of least action. The effect of the virtual mass of the gas bubbles was included. It is demonstrated now that a variational principle in the Langrange form yields the same two-fluid equations.

  4. Inviscid behaviour of fines-rich pyroclastic flows inferred from experiments on gas-particle mixtures [rapid communication

    Microsoft Academic Search

    O. Roche; M. A. Gilbertson; J. C. Phillips; R. S. J. Sparks

    2005-01-01

    Experiments were carried out on granular flows generated by instantaneous release of gas-fluidised, bidisperse mixtures and propagating into a horizontal channel. The mixture consists of fine ( 100 mum) particles of same density, with corresponding grain size ratios of ˜ 2 to 9. Initial fluidisation of the mixture destroys the interparticle frictional contacts, and the flow behaviour then depends on

  5. Preparation of Neutron-activated Xenon for Liquid Xenon Detector Calibration

    E-print Network

    Ni, K; Wongjirad, T M; Kastens, L; Manzur, A; McKinsey, D N

    2007-01-01

    We report the preparation of neutron-activated xenon for the calibration of liquid xenon (LXe) detectors. Gamma rays from the decay of xenon metastable states, produced by fast neutron activation, were detected and their activities measured in a LXe scintillation detector. Following a five-day activation of natural xenon gas with a Cf-252 (4 x 10^5 n/s) source, the activities of two gamma ray lines at 164 keV and 236 keV, from Xe-131m and Xe-129m metastable states, were measured at about 95 and 130 Bq/kg, respectively. We also observed three additional lines at 35 keV, 100 keV and 275 keV, which decay away within a few days. No long-lifetime activity was observed after the neutron activation.

  6. Diffusion of relativistic gas mixtures in gravitational fields

    E-print Network

    Gilberto M. Kremer

    2013-03-26

    A mixture of relativistic gases of non-disparate rest masses in a Schwarzschild metric is studied on the basis of a relativistic Boltzmann equation in the presence of gravitational fields. A BGK-type model equation of the collision operator of the Boltzmann equation is used in order to compute the non-equilibrium distribution functions by the Chapman-Enskog method. The main focus of this work is to obtain Fick's law without the thermal-diffusion cross-effect. Fick's law has four contributions, two of them are the usual terms proportional to the gradients of concentration and pressure. The other two are of the same nature as those which appears in Fourier's law in the presence of gravitational fields and are related with an acceleration and gravitational potential gradient, but unlike Fourier's law these two last terms are of non-relativistic order. Furthermore, it is shown that the coefficients of diffusion depend on the gravitational potential and they become larger than those in the absence of it.

  7. Ignition of a combustible gas mixture by a laser spark excited in the reactor volume

    SciTech Connect

    Kazantsev, S. Yu.; Kononov, I. G.; Kossyi, I. A.; Tarasova, N. M.; Firsov, K. N. [Russian Academy of Sciences, Prokhorov Institute of General Physics (Russian Federation)

    2009-03-15

    Ignition of a stoichiometric CH{sub 4}: O{sub 2} mixture by a laser spark excited in the reactor volume is studied experimentally. It is found that the spark initiates a feebly radiating incomplete-combustion wave, which is much faster than the combustion wave, but is substantially slower than the detonation wave. With a time delay of 500-700 {mu}s, a bright optical flash occupying the entire chamber volume is observed, which indicates fast (involving branching chain reactions) ignition of the gas mixture. A conclusion is drawn regarding the common nature of the process of ignition of a combustible gas mixture by a laser spark excited in the reactor volume and the previously investigated initiation of combustion by laser sparks excited at solid targets, high-power microwave discharges, and high-current gliding discharges.

  8. Aging of proportional counters with gas mixtures containing impurities of aromatic hydrocarbons

    Microsoft Academic Search

    H. Andersson; T. Andersson; J. Heino; J. Huovelin; K. Kurvinern; R. Lauhakangas; S. Nenonen; A. Numminen; J. Ojala; R. Orava; J. Schultz; H. Sipila; O. Vilhu

    2004-01-01

    The aging characteristics of some aromatic hydrocarbons and some other solvents with a ring like molecule structure are systematically studied. The concentrations ranging from a few ppm to several hundred ppm were investigated. Gas mixtures with and without hydrocarbons were tested as well, to find out whether the hydrocarbons contribute to the plasma polymerisation process. An array of twelve single-wire

  9. An Application of Space-Based Gas Mixtures for Joule-Thompson Cryocoolers

    Microsoft Academic Search

    V. T. Arkhipov; O. V. Yevdokimova; M. P. Lobko; V. V. Yakuba

    1999-01-01

    An extension of deepspace research, specifically, the work done on Alpha program, will inevitably require new and different cryostating systems. The primary differences will be in the areas of cooling power and temperature. One variant which can be used with J-T cryocoolers is the application of diverse gas mixtures which can work over a large temperature range. We have found

  10. Method of gas mixtures discrimination based on sensor array, temporal response and data driven approach

    Microsoft Academic Search

    A. Szczurek; M. Maciejewska; B. Flisowska-Wiercik

    2011-01-01

    This work presents a method of gas mixtures discrimination. The principal concept of the method is to apply measurement data provided by a combination of sensors at single time point of their temporal response as input of the discrimination models. The pattern data combinations are selected for classes of target gases based on the criterion of 100% efficient discrimination. Combinations

  11. Design of a cyclone separator for the separation of gas-liquid mixtures

    Microsoft Academic Search

    A. S. Zhikharev; A. M. Kutepov; V. V. Solov'ev

    1985-01-01

    A procedure has been developed at the MIKhMe for the design of a hollow cyclone separator with a rectangular tangential inlet of the gas-liquid mixture near the bottom. The procedure is based on the results of theoretical and experimental investigations of the cyclone and allows one to determine the geometrical dimensions and the operating regime of the cyclone which corresponds

  12. Clathrate hydrate equilibrium data for the gas mixture of carbon dioxide and nitrogen in the

    E-print Network

    Paris-Sud XI, Université de

    1 Clathrate hydrate equilibrium data for the gas mixture of carbon dioxide and nitrogen Department, CNRS-UMR 5307 LGF, 158 cours Fauriel, 42023 St Etienne, FRANCE. ABSTRACT Carbon dioxide the mole fraction of CO2 in the carbon dioxide + nitrogen + cyclopentane mixed hydrate phase, both defined

  13. Method and apparatus for perforating at cutting with a solid fueled gas mixture

    Microsoft Academic Search

    A. J. Woytek; J. T. Lileck; E. J. Steigerwalt

    1984-01-01

    A method for cutting pipe casings and concrete liners or perforating the same and localized portions of surrounding strata in an earth bore is set forth wherein a gas phase cutting or perforating jet mixture of fluorine and nitrogen trifluoride is delivered to the cutting or perforation site from the decomposition of a solid, normally stable, perfluoroammonium salt. An appropriate

  14. Method and device for forming mixture gas in direct injection type internal combustion engine

    Microsoft Academic Search

    A. Saito; M. Yamada; K. Imai; K. Kawamura; M. Kimura

    1987-01-01

    A mixture gas formation method is described for a direct fuel injection type internal combustion engine having a piston with a recess forming a combustion space, air intake means with swirling means for swirling intake air to be supplied to the combustion space, and an intermittent type swirl injection nozzle having at least one tangential passage for swirling fuel, for

  15. Influence of oxygen and moisture content on electron life time in helium-isobutane gas mixtures

    NASA Astrophysics Data System (ADS)

    Golovatyuk, V.; Grancagnolo, F.; Perrino, R.

    2001-04-01

    The presented results refer to 90% helium and 10% isobutane gas mixture. Single electrons have been used to measure the attachment coefficient and drift velocity in homogeneous electric fields in the range from 100 to 1000 Vcm -1. Water vapor and oxygen concentrations varied from 350 ppm up 1.1%, and from 5 to 900 ppm, respectively.

  16. Combustion of a coal-water mixture in a gas turbine combustor

    Microsoft Academic Search

    1985-01-01

    An experimental program is under way to evaluate the atomization, combustion, turbine blading tolerance, and emissions for a coal-water mixture (CWM) fuel. Combustor and turbine components from an MS6001 commercial gas turbine are being utilized with modifications accommodate the CWM characteristics. Raw coal is physically cleaned, or beneficiated, to achieve less than 1% ash; this cleaned coal is then treated

  17. Transverse electrodeless RF discharge excitation of high-pressure laser gas mixtures

    Microsoft Academic Search

    C. P. Christensen; F. X. Powell; N. Djeu

    1980-01-01

    Self-sustained discharge excitation of CO2, Xe, F, and HF laser transitions using a transverse electrodeless RF (TERF) configuration is investigated. Homogeneous long-duration excitation of high-pressure laser gas mixtures is demonstrated, and the operating characteristics associated with the four laser species in this discharge environment are explored.

  18. EVALUATION OF THE EFFICIENCY OF INDUSTRIAL FLARES: H2S GAS MIXTURES AND PILOT ASSISTED FLARES

    EPA Science Inventory

    The report is the fourth in a series on a research program which will result in quantification of emissions from, and efficiencies of, industrial flares. The report gives test data on the combustion efficiency and destruction efficiency of (1) gas mixtures containing H2S, and (2)...

  19. Tortuosity measurement and the effects of finite pulse widths on xenon gas diffusion NMR studies of porous media

    Microsoft Academic Search

    R. W. Maira; M. D. Hurlimann; P. N. Sen; S. Patz; R. L. Walsworth

    We have extended the utility of NMR as a technique to probe porous media structure over length scales of ;100 -2000 mm by using the spin 1\\/2 noble gas 129Xe imbibed into the system's pore space. Such length scales are much greater than can be probed with NMR diffusion studies of water-saturated porous media. We utilized Pulsed Gradient Spin Echo

  20. Electrochemical separation and concentration of sulfur containing gases from gas mixtures

    DOEpatents

    Winnick, Jack (3805 Woodrail-on-the-Green, Columbia, MO 65201)

    1981-01-01

    A method of removing sulfur oxides of H.sub.2 S from high temperature gas mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The gas mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4.sup.= or, in the case of H.sub.2 S, to S.sup.=. The anions migrate to the anode where they are converted to a stable gaseous form at much greater concentration levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing gas such as hydrogen past the anode.

  1. Dispersion measurement of inert gases and gas mixtures at 800 nm.

    PubMed

    Börzsönyi, A; Heiner, Z; Kalashnikov, M P; Kovács, A P; Osvay, K

    2008-09-20

    Dispersion of femtosecond laser pulses propagating in Ar, He, Kr, N(2), Ne, Xe, and their mixtures is measured by spectrally and spatially resolved interferometry. By varying the gas pressure in a 4.5 m long tube between 0.05 mbar and ambient pressure, the first, second, and third order phase derivatives of broadband laser pulses are determined at 800 nm under standard conditions. The dispersion of gases and gas mixtures obeys the Lorentz-Lorenz formula with an accuracy of 0.7%. Based on the measured pressure dependent dispersion values in the near infrared and the refractive indices available from the literature for the ultraviolet and visible, a pressure dependent Sellmeier-type formula is fitted for each gas. These common form, two-term dispersion equations provide an accuracy between 4.1x10(-9) (Ne) and 4.3x10(-7) (Xe) for the refractive indices, from UV to near IR. PMID:18806842

  2. Magnetic resonance imaging of lungs at ultra-low magnetic field strength using hyperpolarized xenon-129 gas

    NASA Astrophysics Data System (ADS)

    Parra Robles, Juan Miguel

    Conventional proton Magnetic Resonance (MR) imaging has been limited to water rich organs and tissues, with limited success in lungs and airways. With the introduction of Hyperpolarized Noble Gases (HNG's), the low spin concentration in gas-spaces is compensated by the extremely high non-equilibrium magnetizations achievable. This magnetization increase allows the use of field strengths much lower than those currently used in clinical MR systems with advantages such as: increased patient accessibility, reduced cost and image artifacts and less siting restrictions. Until now, the choice of field strength for HNG imaging has been mostly determined by the existing conventional MR systems or on hardware limitations. This work provides a theoretical framework for selection of the optimum field strength for clinical HNG MR imaging systems based on models of the field strength dependence of the achievable signal-to-noise ratio (SNR) and spatial resolution. A methodology for MR imaging of the lungs at very low field strengths is developed by building a system for hyperpolarized 129Xe (HXe) rat lung imaging that uses the fringe field of a superconducting magnet as the source of the static magnetic field. A passive shimming procedure that improves the fringe field homogeneity to the levels required for imaging is theoretically described and used at two field strengths (8.5 mT and 17 mT). Spectra and images of HXe gas in phantoms and excised rat lungs are presented and used to validate the obtained theoretical SNR field dependence for small samples. The issues related to clinical HNG imaging at low fields for both gas-space and dissolved-phase imaging are investigated and possible ways to address them in future are discussed.

  3. Solid xenon radiation detectors

    NASA Astrophysics Data System (ADS)

    Dolinski, Michelle J.

    2014-03-01

    Cryogenic liquid xenon detectors have become a popular technology in the search for rare events, such as dark matter interactions and neutrinoless double beta decay. The power of the liquid xenon detector technology is in the combination of the ionization and scintillation signals, resulting in particle discrimination and improved energy resolution over the ionization-only signal. The improved energy resolution results from a unique anti-correlation phenomenon that has not been described from first principles. Solid xenon bolometers, under development at Drexel University, are expected to have excellent counting statistics in the phonon channel, with energy resolution of 0.1% or better. This additional energy channel may offer the final piece of the puzzle in understanding liquid xenon detector energy response. Supported by a grant from the Charles E. Kaufman Foundation.

  4. The structure of variable property, compressible mixing layers in binary gas mixtures

    NASA Technical Reports Server (NTRS)

    Kozusko, F.; Grosch, C. E.; Jackson, T. L.; Kennedy, Christipher A.; Gatski, Thomas B.

    1996-01-01

    We present the results of a study of the structure of a parallel compressible mixing layer in a binary mixture of gases. The gases included in this study are hydrogen (H2), helium (He), nitrogen (N2), oxygen (02), neon (Ne) and argon (Ar). Profiles of the variation of the Lewis and Prandtl numbers across the mixing layer for all thirty combinations of gases are given. It is shown that the Lewis number can vary by as much as a factor of eight and the Prandtl number by a factor of two across the mixing layer. Thus assuming constant values for the Lewis and Prandtl numbers of a binary gas mixture in the shear layer, as is done in many theoretical studies, is a poor approximation. We also present profiles of the velocity, mass fraction, temperature and density for representative binary gas mixtures at zero and supersonic Mach numbers. We show that the shape of these profiles is strongly dependent on which gases are in the mixture as well as on whether the denser gas is in the fast stream or the slow stream.

  5. Use of electroluminescence of gas mixtures for optical data acquisition from wire chambers

    SciTech Connect

    Polyakov, V.A.; Rykalin, V.I.; Tskhadadze, E.G.

    1988-07-01

    The radiation spectra, electroluminescence light yields, and gas-amplification factors of mixtures of Ar and Ne with inorganic and organic admixtures in a wire chamber operating in the proportional and self-quenched streamer (SQS) modes are measured. Maximum light yields of 2 x 10/sup 7/ photons for mixtures of Ar + acetone + white spirit and 1.1 x 10/sup 7/ photons for Ar + CO/sub 2/ + ethanol + white spirit in the SQS mode are obtained. Three methods for optical data acquisition from wire chambers are tested. Best results are obtained when spectrum-shifting strips and fibers are placed behind the cathode planes of the chamber.

  6. Size effect in impuriton gas of 3He-4He superfluid mixture

    NASA Astrophysics Data System (ADS)

    Adamenko, I. N.; Bortnik, L. N.; Chervanyov, A. I.

    1999-04-01

    The flow of quasiparticle gas under the action of gradients of thermodynamic quantities in a volume filled with a powder (crocus) is considered. The exact solution of the kinetic equation is obtained in terms of the matrix elements of the collision integral for quasiparticles and partial cross sections of quasiparticles scattering by crocus. The condition describing a steady nonequilibrium state of the quasiparticle gas in a volume filled with a porous material is determined. The obtained results are valid for arbitrary relations between the frequencies of collisions of quasiparticles with one another and with powder particles. The Knudsen effect in a degenerate quantum gas is studied, and the transition from the Knudsen to hydrodynamic flow of quasiparticle gas is analyzed. The steady nonequilibrium state of the impuriton gas in the 3He-4He superfluid mixture is investigated in a confined geometry.

  7. Reactive sputtering of titanium in Ar/CH4 gas mixture: Target poisoning and film characteristics

    SciTech Connect

    Fouad, O.A.; Rumaiz, A.; Shah, S.

    2009-03-01

    Reactive sputtering of titanium target in the presence of Ar/CH{sub 4} gas mixture has been investigated. With the addition of methane gas to above 1.5% of the process gas a transition from the metallic sputtering mode to the poison mode was observed as indicated by the change in cathode current. As the methane gas flow concentration increased up to 10%, the target was gradually poisoned. The hysteresis in the cathode current could be plotted by first increasing and then subsequently decreasing the methane concentration. X-ray diffraction and X-ray photoelectron spectroscopy analyses of the deposited films confirmed the formation of carbide phases and the transition of the process from the metallic to compound sputtering mode as the methane concentration in the sputtering gas is increased. The paper discusses a sputtering model that gives a rational explanation of the target poisoning phenomenon and shows an agreement between the experimental observations and calculated results.

  8. XENON in medical area: emphasis on neuroprotection in hypoxia and anesthesia

    PubMed Central

    2013-01-01

    Xenon is a medical gas capable of establishing neuroprotection, inducing anesthesia as well as serving in modern laser technology and nuclear medicine as a contrast agent. In spite of its high cost, its lack of side effects, safe cardiovascular and organoprotective profile and effective neuroprotective role after hypoxic-ischemic injury (HI) favor its applications in clinics. Xenon performs its anesthetic and neuroprotective functions through binding to glycine site of glutamatergic N-methyl-D-aspartate (NMDA) receptor competitively and blocking it. This blockage inhibits the overstimulation of NMDA receptors, thus preventing their following downstream calcium accumulating cascades. Xenon is also used in combination therapies together with hypothermia or sevoflurane. The neuroprotective effects of xenon and hypothermia cooperate synergistically whether they are applied synchronously or asynchronously. Distinguishing properties of Xenon promise for innovations in medical gas field once further studies are fulfilled and Xenon’s high cost is overcome. PMID:23369273

  9. Implementation of Ultrasonic Sensing for High Resolution Measurement of Binary Gas Mixture Fractions

    PubMed Central

    Bates, Richard; Battistin, Michele; Berry, Stephane; Bitadze, Alexander; Bonneau, Pierre; Bousson, Nicolas; Boyd, George; Bozza, Gennaro; Crespo-Lopez, Olivier; Riva, Enrico Da; Degeorge, Cyril; Deterre, Cecile; DiGirolamo, Beniamino; Doubek, Martin; Favre, Gilles; Godlewski, Jan; Hallewell, Gregory; Hasib, Ahmed; Katunin, Sergey; Langevin, Nicolas; Lombard, Didier; Mathieu, Michel; McMahon, Stephen; Nagai, Koichi; Pearson, Benjamin; Robinson, David; Rossi, Cecilia; Rozanov, Alexandre; Strauss, Michael; Vitek, Michal; Vacek, Vaclav; Zwalinski, Lukasz

    2014-01-01

    We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity < 5 × 10?5 is demonstrated to leaks of octaflouropropane (C3F8) coolant into nitrogen during a long duration (18 month) continuous study. The sensitivity of the described measurement system is shown to depend on the difference in molecular masses of the two gases in the mixture. The impact of temperature and pressure variances on the accuracy of the measurement is analysed. Practical considerations for the implementation and deployment of long term, in situ ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to processes requiring continuous knowledge of particular binary gas mixture fractions. PMID:24961217

  10. Implementation of ultrasonic sensing for high resolution measurement of binary gas mixture fractions.

    PubMed

    Bates, Richard; Battistin, Michele; Berry, Stephane; Bitadze, Alexander; Bonneau, Pierre; Bousson, Nicolas; Boyd, George; Bozza, Gennaro; Crespo-Lopez, Olivier; Da Riva, Enrico; Degeorge, Cyril; Deterre, Cecile; DiGirolamo, Beniamino; Doubek, Martin; Favre, Gilles; Godlewski, Jan; Hallewell, Gregory; Hasib, Ahmed; Katunin, Sergey; Langevin, Nicolas; Lombard, Didier; Mathieu, Michel; McMahon, Stephen; Nagai, Koichi; Pearson, Benjamin; Robinson, David; Rossi, Cecilia; Rozanov, Alexandre; Strauss, Michael; Vitek, Michal; Vacek, Vaclav; Zwalinski, Lukasz

    2014-01-01

    We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity < 5 × 10(-5) is demonstrated to leaks of octaflouropropane (C3F8) coolant into nitrogen during a long duration (18 month) continuous study. The sensitivity of the described measurement system is shown to depend on the difference in molecular masses of the two gases in the mixture. The impact of temperature and pressure variances on the accuracy of the measurement is analysed. Practical considerations for the implementation and deployment of long term, in situ ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to processes requiring continuous knowledge of particular binary gas mixture fractions. PMID:24961217

  11. Extremely low flow tracheal gas insufflation of helium-oxygen mixture improves gas exchange in a rabbit model of piston-type high-frequency oscillatory ventilation

    PubMed Central

    2013-01-01

    Objective The purpose of this study was to show the effects of the tracheal gas insufflation (TGI) technique on gas exchange using helium-oxygen mixtures during high-frequency oscillatory ventilation (HFOV). We hypothesized that a helium-oxygen mixture delivered into the trachea using the TGI technique (0.3 L/min) would enhance gas exchange during HFOV. Methods Three rabbits were prepared and ventilated by HFOV with carrier 70% helium/oxygen or 70% nitrogen/oxygen gas mixture with TGI in a crossover study. Changing the gas mixture from nitrogen70% to helium70% and back was performed three times per animal with constant ventilation parameters. Results Compared with the nitrogen-oxygen mixture, the helium-oxygen mixture of TGI reduced PaCO2 by 7.6 mmHg (p?mixture than with the nitrogen-oxygen mixture (p?mixture delivered into the trachea using the TGI technique would enhance CO2 elimination and improve oxygenation during HFOV. PMID:23566050

  12. Ionization efficiency studies for xenon ions with thesuperconducting ECR ion source VENUS

    SciTech Connect

    Leitner, Daniela; Lyneis, Claude M.; Todd, DamonS.; Tarvainen,Olli

    2007-06-05

    Ionization efficiency studies for high charge state xenon ions using a calibrated gas leak are presented. A 75% enriched {sup 129}Xe gas leak with a gas flow equivalent to 5.11p{mu}A was used in all the measurements. The experiments were performed at the VENUS (Versatile ECR ion source for Nuclear Science) ion source for 18 GHz, 28 GHz and double frequency operation. Overall, total ionization efficiencies close to 100% and ionization efficiencies into a single charge state up to 22% were measured. The influence of the biased disk on the ionization efficiency was studied and the results were somewhat surprising. When the biased disk was removed from the plasma chamber, the ionization efficiency was dramatically reduced for single frequency operation. However, using double frequency heating the ionization efficiencies achieved without the biased disk almost matched the ionization efficiencies achieved with the biased probe. In addition, we have studied the influence of the support gas on the charge state distribution of the xenon ions. Either pure oxygen or a mixture of oxygen and helium were used as support gases. The addition of a small amount of helium can increase the ionization efficiency into a single charge state by narrowing the charge state distribution. Furthermore by varying the helium flow the most efficient charge state can be shifted over a wide range without compromising the ionization efficiency. This is not possible using only oxygen as support gas. Results from these studies are presented and discussed.

  13. Gas Hydrate Equilibrium Measurements for Multi-Component Gas Mixtures and Effect of Ionic Liquid Inhibitors 

    E-print Network

    Othman, Enas Azhar

    2014-04-07

    Qatar holds the world's third-largest proven reserves of natural gas at 885 trillion cubic feet according to a recent report. Because of its desert climate, gas hydrate formation may seem an unlikely event in Qatar. However, ...

  14. Two-Dimensional Gas-Phase Separations Coupled to Mass Spectrometry for Analysis of Complex Mixtures

    SciTech Connect

    Tang, Keqi; Li, Fumin; Shvartsburg, Alexandre A.; Strittmatter, Eric F.; Smith, Richard D.

    2005-10-01

    Ion mobility spectrometry (IMS) has been explored for decades, and its versatility in separation and identification of gas-phase ions, including in isomeric mixtures, is well established. Recently, field asymmetric waveform IMS (FAIMS) has been gaining acceptance in similar applications. Coupled to mass spectrometry (MS), both IMS and FAIMS have shown the potential for broad utility in proteomics and other biological analyses. A major attraction of these separations is extremely high speed, exceeding that of condensed-phase alternatives by orders of magnitude. However, modest separation peak capacities have limited the utility of FAIMS and IMS for analyses of complex mixtures. We report 2-D gas-phase separations that join FAIMS to IMS, in conjunction with high-resolution and accuracy time-of-flight MS. Evaluation of FAIMS/IMS/TOF performance using a protein mixture tryptic digest reveals high orthogonality between FAIMS and IMS dimensions, and hence the benefit of FAIMS filtering prior to IMS/MS. The effective overall peak capacities are {approx}500 for FAIMS/IMS separations, and {approx}106 for 3-D FAIMS/IMS/MS analyses of tryptic peptides. Implementation of FAIMS/IMS and IMS/MS interfaces using electrodynamic ion funnels greatly improves sensitivity, making FAIMS/IMS/MS a potential platform for ultrahigh-throughput analyses of complex mixtures.

  15. Study of thermite mixture consolidated by the cold gas dynamic spray process

    NASA Astrophysics Data System (ADS)

    Bacciochini, A.; Maines, G.; Poupart, C.; Akbarnejad, H.; Radulescu, M.; Jodoin, B.; Zhang, F.; Lee, J. J.

    2014-05-01

    The present study focused on the cold gas dynamic spray process for manufacturing porosity free, finely structured energetic materials with high reactivity and structural integrity. The experiments have focused the reaction between the aluminium and metal oxide, such as Al-CuO system. The consolidation of the materials used the cold gas dynamic spray technique, where the particles are accelerated to high speeds and consolidated via plastic deformation upon impact. Reactive composites are formed in arbitrary shapes with close to zero porosity and without any reactions during the consolidation phase. Reactivity of mixtures has been investigated through flame propagation analysis on cold sprayed samples and compacted powder mixture. Deflagration tests showed the influence of porosity on the reactivity.

  16. Study of thermite mixtures consolidated by cold gas dynamic spray process

    NASA Astrophysics Data System (ADS)

    Bacciochini, Antoine; Maines, Geoffrey; Poupart, Christian; Radulescu, Matei; Jodoin, Bertrand; Lee, Julian

    2013-06-01

    The present study focused on the cold gas dynamic spray process for manufacturing finely structured energetic materials with high reactivity, vanishing porosity, as well as structural integrity and arbitrary shape. The experiments have focused the reaction between the aluminum and metal oxides, such as Al-CuO and Al-MoO3 systems. To increase the reactivity, an initial mechanical activation was achieved through interrupted ball milling. The consolidation of the materials used the supersonic cold gas spray technique, where the particles are accelerated to high speeds and consolidated via plastic deformation upon impact, forming activated nano-composites in arbitrary shapes with close to zero porosity. This technique permits to retain the feedstock powder micro-structure and prevents any reactions during the consolidation phase. Reactivity of mixtures has been investigated through flame propagation analysis on cold sprayed samples and compacted powder mixture. Deflagration tests showed the influence of porosity on the reactivity.

  17. Monte Carlo Method for Electron Transport Simulation in SF6-CO2 Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Xiao, Deng-Ming; Xu, Xin; Yang, Jing-lin

    2004-02-01

    The Monte Carlo method is used for the simulation of the electron transport of SF6-CO2 gas mixtures in a uniform electric field. The electron swarm behavior of SF6-CO2 gas mixtures is calculated and analyzed over the E/N range of 272.83-364.51 Td (1 Td = 10-21 V\\cdotm2) and compared with the experimental results. The result of Monte Carlo simulation shows that the present set of cross sections of SF6 and CO2 revised according to the experimental results gives the values of swarm parameters such as ionization and electron attachment coefficients, drift velocity and longitudinal diffusion coefficient which are in excellent agreement with the respective measurement results for the relatively wide range of E/N.

  18. Temperature dependent gain of the atomic xenon laser Gregory A. Hebne?)

    E-print Network

    Kushner, Mark

    the gain and efficiency of the atomic xenon laser at gas tem- peratures less than 325 K,1-3,6the functionalTemperature dependent gain of the atomic xenon laser Gregory A. Hebne?) Sandia National(3/2),-6p(5/2),] and 2.03 pm [5d(3/2)t- 6p( 3/2) t] atomic xenon transitions for gas temperatures

  19. Artificial neural networks to correlate in-tube turbulent forced convection of binary gas mixtures

    Microsoft Academic Search

    Gerardo Diaz; Antonio Campo

    2009-01-01

    Turbulent forced convection correlations are documented in the literature for air, gases and vapors (Pr?0.7), for common liquids (Pr>1) and for liquid metals (Pr0.03). In spite of this, there is a small gap in the Pr sub-interval between 0.1 and 1.0, which is occupied by binary gas mixtures. In this paper, data for turbulent forced convection for the in-tube flow

  20. Quantum scattering theory of rotational relaxation and spectral line shapes in H2He gas mixtures

    Microsoft Academic Search

    Richard Shafer; Roy G. Gordon

    1973-01-01

    A systematic study is presented of the rotational relaxation and spectral line shape properties of dilute gas mixtures of H2 in He, in an effort to determine the radial and angular dependence of the H2&sngbnd;He intermolecular potential. The quantum mechanical theory of relaxation in gases is reviewed, and we express the results in terms of a matrix of cross sections

  1. Damage-free wafer cleaning by water and gas mixture jet

    Microsoft Academic Search

    Y. Hirota; I. Kanno; K. Fujiwara; H. Nagayasu; S. Shimose

    2005-01-01

    A damage-free single wafer cleaning method using a water and gas mixture jet (two-fluid jet) has been developed. It was confirmed that the combination cleaning process of the two-fluid jet and APM (NH4OH\\/H2O2\\/DIW) dispense showed higher cleaning performance than that of conventional batch-type APM cleaning for 65 nm gate patterns. The cleaning performance of the two-fluid jet was improved by

  2. Viscous shock layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous shock layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially symmetric flow fields. Solutions are obtained using an implicit finite difference scheme and results are presented for hypersonic flow over spherically blunted cone configurations at free stream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  3. Viscous-shock-layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous-shock-layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially-symmetric flow fields. Solutions were obtained using an implicit finite-difference scheme and results are presented for hypersonic flow over spherically-blunted cone configurations at freestream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  4. Low-pressure inductive gas discharges in Ar, Kr, He and Ar+Hg mixture

    Microsoft Academic Search

    Natalia Denisova; Revalde Gita; Skudra Atis

    2009-01-01

    This paper presents results of theoretical and experimental investigations of high-frequency (HF) inductive gas discharges in Ar, Kr, He and Ar+Hg mixture in the pressure area of 0.1-10 Torr. The HF inductive discharges are known as effective sources of spectral lines. Our estimations predict that due to the skin-effect, high-frequency inductive discharge should have more high line intensity if compare

  5. Electron interaction cross sections for a low-temperature 'plasma-like' gas mixture

    NASA Astrophysics Data System (ADS)

    Hargreaves, L. R.; Brunton, J. R.; Brunger, M. J.; Buckman, S. J.

    2010-12-01

    Electron interaction cross sections for species found in low-temperature industrial plasma environments are a crucial component to allow for accurate modeling of those plasmas. However, such data are still rarely reported in the literature, due to the complexities of working with such highly reactive species in a laboratory. Here, absolute differential cross section measurements for a 'plasma-like' gas mixture, containing CF3I, CF3, I2, I and C2F6, are reported.

  6. Noble gas mixture CW hollow cathode laser with internal anode system

    Microsoft Academic Search

    K. Rozsa; M. Janossy; J. Bergou; L. Csillag

    1977-01-01

    A hollow cathode discharge tube with internal anodes was found to operate at significantly higher discharge voltages than a conventional HCD. A laser tube having internal anodes was constructed and laser operation was investigated in He-Kr, He-Ar and He-Ne-Xe gas mixtures. Due to the increased voltage low threshold currents and increased output power were obtained at the 4694 A Kr

  7. On the excitation mechanism of hollow cathode CW noble gas mixture ion lasers

    Microsoft Academic Search

    M. Janossy; P. Tuovinen

    1979-01-01

    CW laser operation was observed at transitions of Kr II, Ar II and Xe II in noble gas mixture hollow cathode discharges. The\\u000a laser transitions are excited in two steps: 1) ionization of atoms, 2) excitation of ions to the upper laser state. It is\\u000a shown that in contrast to the pulsed positive column system the dominant process of ionization

  8. Sound speed in liquid-gas mixtures: Water-air and water-steam

    Microsoft Academic Search

    Susan Werner Kieffer

    1977-01-01

    The sound speed of a two-phase fluid, such as a magma-gas, water-air, or water-steam mixture, is dramatically different from the sound speed of either pure component. In numerous geologic situations the sound speed of such two-phase systems may be of interest: in the search for magma reservoirs, in seismic exploration of geothermal areas, in prediction of P wave velocity decreases

  9. Carburization\\/Oxidation Behavior of Alloy Haynes214 in Methane–Hydrogen Gas Mixtures

    Microsoft Academic Search

    I. M. Allam

    2009-01-01

    The excellent resistance of Alloy Haynes-214 to carburization at elevated temperatures is attributed to the formation of a\\u000a protective surface layer of Al2O3, resulting from the reaction of trace oxygen impurity in the gas phase with the Al-enriched surface. Lower carburization\\u000a resistance below 1000 °C is manifested by increased carbon pick-up and degradation of mechanical properties. Exposures in\\u000a CH4\\/H2 gas mixtures

  10. Adsorption process to recover hydrogen from feed gas mixtures having low hydrogen concentration

    DOEpatents

    Golden, Timothy Christopher; Weist, Jr., Edward Landis; Hufton, Jeffrey Raymond; Novosat, Paul Anthony

    2010-04-13

    A process for selectively separating hydrogen from at least one more strongly adsorbable component in a plurality of adsorption beds to produce a hydrogen-rich product gas from a low hydrogen concentration feed with a high recovery rate. Each of the plurality of adsorption beds subjected to a repetitive cycle. The process comprises an adsorption step for producing the hydrogen-rich product from a feed gas mixture comprising 5% to 50% hydrogen, at least two pressure equalization by void space gas withdrawal steps, a provide purge step resulting in a first pressure decrease, a blowdown step resulting in a second pressure decrease, a purge step, at least two pressure equalization by void space gas introduction steps, and a repressurization step. The second pressure decrease is at least 2 times greater than the first pressure decrease.

  11. Mixture of Tonks-Girardeau gas and Fermi gas in one-dimensional optical lattices

    E-print Network

    Chen, Shu; Gu, Shi-Jian; 10.1103/PhysRevA.82.053625

    2010-01-01

    We study the Bose-Fermi mixture with infinitely boson-boson repulsion and finite boson-Fermion repulsion. By using a generalized Jordan-Wigner transformation, we show that the system can be mapped to a repulsive Hubbard model and thus can be solved exactly for the case with equal boson and fermion masses. By using the Bethe-ansatz solutions, we investigate the ground state properties of the mixture system. Our results indicate that the system with commensurate filling $n=1$ is a charge insulator but still a superfluid with non-vanishing superfluid density. We also briefly discuss the case with unequal masses for bosons and fermions.

  12. Model of a low pressure argon-xenon positive column

    SciTech Connect

    Sommerer, T.J. [General Electric Co., Schenectady, NY (United States). Corporate Research and Development

    1994-12-31

    The authors are investigating various discharge-phosphor systems with the goal of developing a mercury-free replacement for existing fluorescent lamps. The initial work centers on a low pressure argon-xenon positive column discharge combined with a quantum splitting phosphor. This talk will outline the modeling issues and report results from modeling of the argon-xenon positive column. The model predictions will be compared with experimental measurements described in detail elsewhere at this conference. Xenon is the active radiating gas in a low pressure argon-xenon positive column, emitting resonance radiation near 147 nm. Argon serves as a relatively inactive buffer gas to retard diffusion of the charged species to the wall and thereby control the electron temperature. For use in a fluorescent lamp, they want to find conditions which maximize the efficiency for conversion of input electrical power to emitted 147 nm radiation. Acceptably high efficiency must be obtained simultaneously with power densities comparable to existing argon-mercury fluorescent lamps, around 0.4 W per cm of tube length. Seven to none electronically excited levels of the xenon atom are included in the present model. For the conditions modeled to date, they find that xenon ions are produced predominantly by electron impact on the lowest-lying excited xenon levels.

  13. 1-D fluid simulations of a helium-xenon filled AC plasma display panel

    SciTech Connect

    Veerasingam, R.; Campbell, R.B.; McGrath, R.T. [Sandia National Labs., Albuquerque, NM (United States)

    1995-12-31

    A one dimensional multi-species fluid model has been developed to analyze the operation of an ac plasma display panel (AC PDP) that is filled with a helium-xenon Penning mixture. The AC PDP is a promising candidate in the flat panel display industry especially for information displays having large screen areas. A PDP consists of a matrix of gas cells operating at pressures of several hundred Torr. In each cell a micro discharge is initiated using special driving circuitry that typically have address, sustain and erase pulse wave forms. The AC PDP has a memory characteristic which eliminates the need for a refresh pulse once a cell has been addressed. To ensure that a single sustain pulse can maintain a cell in the ON or OFF state, a large memory margin is essential. The model can be used for parametric studies to observe the effects of variations in pressure, gap width, and percentage of xenon on the first on and first off voltages, bi-stable margin and on xenon metastable and dimer populations. The authors present results of such parametric variations and comparisons with experiments.

  14. Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures

    SciTech Connect

    Aines, Roger D. (Livermore, CA); Bourcier, William L. (Livermore, CA)

    2010-11-09

    A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

  15. Carbon ion pump for removal of carbon dioxide from combustion gas and other gas mixtures

    DOEpatents

    Aines, Roger D.; Bourcier, William L.

    2014-08-19

    A novel method and system of separating carbon dioxide from flue gas is introduced. Instead of relying on large temperature or pressure changes to remove carbon dioxide from a solvent used to absorb it from flue gas, the ion pump method, as disclosed herein, dramatically increases the concentration of dissolved carbonate ion in solution. This increases the overlying vapor pressure of carbon dioxide gas, permitting carbon dioxide to be removed from the downstream side of the ion pump as a pure gas. The ion pumping may be obtained from reverse osmosis, electrodialysis, thermal desalination methods, or an ion pump system having an oscillating flow in synchronization with an induced electric field.

  16. Using an 80% CF4+20% CO2 gas mixture to recover aged anode wires in proportional chambers

    NASA Astrophysics Data System (ADS)

    Gavrilov, G. E.; Aksenov, D. A.; Conti, R.; Fetisov, A. A.; Krivchitch, A. G.; Maysuzenko, D. A.; Shvecova, N. Yu.; Vakhtel, V. M.

    2012-12-01

    A technique to recover a gas proportional counter with an aged anode wire using a glow discharge in an 80%CF4+20%CO2 gas mixture, has been developed and tested. Studies of aging effects were carried out under sustained irradiation by an intense 90Sr ?-source of straw proportional counters operated with a 60%Ar+30%CO2+10%CF4 gas mixture. Special attention was paid to the aging mechanism of the anode wires. Our experience showed that using a given gas mixture the swelling of the anode wires is a typical mode of aging that leads to degradation of the gas gain. The proposed method restores the gas gain and the signal amplitude in the damaged zone of the wire. SEM/XEM analysis confirmed that the tungsten oxide deposits have been removed.

  17. Gas-jet synthesis of diamond-like films from an H2 + CH4 gas mixture glow

    NASA Astrophysics Data System (ADS)

    Emel'yanov, A. A.; Rebrov, A. K.; Yudin, I. B.

    2014-03-01

    Synthesis of diamond-like coatings from a high-velocity flow of gas mixtures in flow regimes from free-molecular to continuum with flow velocities from hundreds to thousands meters per second at different specific flow rates and temperatures in the case of activation of gases on hot surfaces is studied experimentally. Deposition of carbon films at low (less than 0.15 Pa) and high (2600 Pa) pressures from a mixture of hydrogen and methane is considered. The hydrogen flow is computed by the Direct Simulation Monte Carlo (DSMC) method in accordance with test conditions with given surface temperatures and chemical transformations on the surfaces. It is found that coatings obtained at the high pressure contain particles typical for diamonds and unusual inclusions shaped as prisms with a hexagonal cross section.

  18. Thermodynamic stability, spectroscopic identification, and gas storage capacity of CO2-CH4-N2 mixture gas hydrates: implications for landfill gas hydrates.

    PubMed

    Lee, Hyeong-Hoon; Ahn, Sook-Hyun; Nam, Byong-Uk; Kim, Byeong-Soo; Lee, Gang-Woo; Moon, Donghyun; Shin, Hyung Joon; Han, Kyu Won; Yoon, Ji-Ho

    2012-04-01

    Landfill gas (LFG), which is primarily composed of CH(4), CO(2), and N(2), is produced from the anaerobic digestion of organic materials. To investigate the feasibility of the storage and transportation of LFG via the formation of hydrate, we observed the phase equilibrium behavior of CO(2)-CH(4)-N(2) mixture hydrates. When the specific molar ratio of CO(2)/CH(4) was 40/55, the equilibrium dissociation pressures were gradually shifted to higher pressures and lower temperatures as the mole fraction of N(2) increased. X-ray diffraction revealed that the CO(2)-CH(4)-N(2) mixture hydrate prepared from the CO(2)/CH(4)/N(2) (40/55/5) gas mixture formed a structure I clathrate hydrate. A combination of Raman and solid-state (13)C NMR measurements provided detailed information regarding the cage occupancy of gas molecules trapped in the hydrate frameworks. The gas storage capacity of LFG hydrates was estimated from the experimental results for the hydrate formations under two-phase equilibrium conditions. We also confirmed that trace amounts of nonmethane organic compounds do not affect the cage occupancy of gas molecules or the thermodynamic stability of LFG hydrates. PMID:22380606

  19. Mixture distribution and flame propagation in a heavy-duty liquid petroleum gas engine with liquid phase injection

    Microsoft Academic Search

    S Oh; C Bae

    2004-01-01

    Enhanced mixture preparation by liquid phase injection on to the port could promote the application of liquefied petroleum gas (LPG) in spark ignition (SI) engines. Mixture distribution and flame propagation of the liquid phase LPG injection (LPLI) engine with a large bore size were investigated in a single-cylinder optical engine which had optical accesses through both sides of the cylinder

  20. Method of producing a methane rich gas mixture from mine gas

    Microsoft Academic Search

    E. Richter; K. Giessler; K. Knoblauch; W. Korbacher

    1985-01-01

    A pressure-swing adsorption system is used to enrich the methane content of mine gas obtained from bores around mine shafts or galleries from the customary 25 to 45% by volume to a product gas quality of 50% by volume. Using a carbon molecular sieve adsorbent, the adsorption is carried out at 5 to 8 bar and is followed by a

  1. Xenon in chondritic metal.

    NASA Astrophysics Data System (ADS)

    Marti, K.; Kim, J. S.; Lavielle, B.; Pellas, P.; Perron, C.

    1989-10-01

    The authors report xenon isotopic abundances observed in the stepwise release of noble gases in a high-purity metal separate of the Forest Vale (H4) chondrite. They identify a 244Pu-derived fission component, due to recoils into the metal, a cosmic-ray-produced spallation component and a new trapped component which is isotopically distinct from known solar system reservoirs. The authors discuss several processes which might account for observed isotopic shifts and conclude that the signature of FVM xenon may provide clues regarding the origin of chondritic metal.

  2. Adiabatic temperature changes of magma-gas mixtures during ascent and eruption

    USGS Publications Warehouse

    Mastin, L.G.; Ghiorso, M.S.

    2001-01-01

    Most quantitative studies of flow dynamics in eruptive conduits during volcanic eruptions use a simplified energy equation that ignores either temperature changes, or the thermal effects of gas exsolution. In this paper we assess the effects of those simplifications by analyzing the influence of equilibrium gas exsolution and expansion on final temperatures, velocities, and liquid viscosities of magma-gas mixtures during adiabatic decompression. For a given initial pressure (p1), temperature (T1) and melt composition, the final temperature (Tf) and velocity (Umax) will vary depending on the degree to which friction and other irreversible processes reduce mechanical energy within the conduit. The final conditions range between two thermodynamic end members: (1) Constant enthalpy (dh=0), in which Tf is maximal and no energy goes into lifting or acceleration; and (2) constant entropy (ds=0), in which Tf is minimal and maximum energy goes into lifting and acceleration. For ds=0, T1=900 ??C and p1=200 MPa, a water-saturated albitic melt cools by ???200 ??C during decompression, but only about 250 ??C of this temperature decrease can be attributed to the energy of gas exsolution per se: The remainder results from expansion of gas that has already exsolved. For the same T1 and p1, and dh=0, Tf is 10-15 ??C hotter than T1 but is about 10-25 ??C cooler than Tf in similar calculations that ignore the energy of gas exsolution. For ds=0, p1=200 MPa and T1= 9,000 ??C, assuming that all the enthalpy change of decompression goes into kinetic energy, a water-saturated albitic mixture can theoretically accelerate to ???800 m/s. Similar calculations that ignore gas exsolution (but take into account gas expansion) give velocities about 10-15% higher. For the same T1, p1 = 200 MPa, and ds = 0, the cooling associated with gas expansion and exsolution increases final melt viscosity more than 2.5 orders of magnitude. For dh = 0, isenthalpic heating decreases final melt viscosity by about 0.7 orders of magnitude. Thermal effects of gas exsolution are responsible for less than 10% of these viscosity changes. Isenthalpic heating could significantly reduce flow resistance in eruptive conduits if heat generation were concentrated along conduit walls, where shearing is greatest. Isentropic cooling could enhance clast fragmentation in near-surface vents in cases where extremely rapid pressure drops reduce gas temperatures and chill the margins of expanding pyroclasts.

  3. SF 6 quenched gas mixtures for streamer mode operation of RPCs at very low voltages

    NASA Astrophysics Data System (ADS)

    Aielli, G.; Camarri, P.; Cardarelli, R.; Di Ciaccio, A.; Di Stante, L.; Liberti, B.; Paoloni, A.; Pastori, E.; Santonico, R.

    2002-11-01

    In the present paper we describe a search for gases that allow to reduce the energy of the electrical discharge produced in Resistive Plate Chambers (RPCs) operated in streamer mode, by reducing both the operating voltage and the released charge. This can be achieved, with current gas mixtures of argon, tetrafluoroethane (TFE) and isobutane, by reducing the total amount of quenching components (TFE+isobutane) down to 10-15% and compensating for the lower gas quenching power with the addition of small amounts of SF 6. We show here that SF 6, even for concentrations as low as 1% or less, has a strong effect in reducing the delivered charge in low quenched gases and allows to achieve a proper working mode of the RPC even at voltages as low as 4- 5 kV over a 2 mm gas gap.

  4. Kinetic model for the vibrational energy exchange in flowing molecular gas mixtures. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Offenhaeuser, F.

    1987-01-01

    The present study is concerned with the development of a computational model for the description of the vibrational energy exchange in flowing gas mixtures, taking into account a given number of energy levels for each vibrational degree of freedom. It is possible to select an arbitrary number of energy levels. The presented model uses values in the range from 10 to approximately 40. The distribution of energy with respect to these levels can differ from the equilibrium distribution. The kinetic model developed can be employed for arbitrary gaseous mixtures with an arbitrary number of vibrational degrees of freedom for each type of gas. The application of the model to CO2-H2ON2-O2-He mixtures is discussed. The obtained relations can be utilized in a study of the suitability of radiation-related transitional processes, involving the CO2 molecule, for laser applications. It is found that the computational results provided by the model agree very well with experimental data obtained for a CO2 laser. Possibilities for the activation of a 16-micron and 14-micron laser are considered.

  5. Selective extraction of pesticides from lipid-containing matrixes using supercritical binary gas mixtures.

    PubMed

    King, J W; Zhang, Z

    1998-04-01

    When supercritical carbon dioxide is used for extraction of trace compounds from lipid-rich samples, the resulting extract can contain a substantial amount of lipid coextractive which interferes in the subsequent chromatographic analysis. In this case, a cleanup step, which is time-consuming, is required in order to remove or reduce the lipid content in the extract. In this study, we report on a new approach for the extraction of trace compounds which significantly reduces the quantity of lipid coextractives, thereby eliminating the need for a sample cleanup step. An autoclave high-pressure reactor equipped with a mechanical stirring device was used for mixing gases, such as carbon dioxide and nitrogen, to generate the desired fluid mixtures. The composition of the mixtures could be adjusted by two mass flow controllers prior to the autoclave mixing device. The generated carbon dioxide/nitrogen binary mixtures were then employed to facilitate supercritical fluid extraction (SFE) at high pressures and elevated temperatures. The pressurized CO(2)/nitrogen binary fluid mixture demonstrated sufficient solvation power for quantitative recoveries of trace fortified organophosphorus and incurred organochlorine pesticides from poultry fat while significantly reducing lipid solubility in the fluid. This allowed the development of a method that produced an extract with minimal lipid content that could be used directly for gas chromatographic analysis, thereby eliminating the need to clean-up the extract. PMID:21644737

  6. Xenon diffusion studies with prompt gamma activation analysis

    Microsoft Academic Search

    Carlos A. Rios Perez; Justin D. Lowrey; Steven Biegalski; Mark R. Deinert

    Developing a better understanding of xenon transport through porous systems is critical to predicting how this gas will enter\\u000a the atmosphere after a below ground nuclear weapons test. Radioxenon monitoring is a vital part of the Comprehensive Nuclear-Test-Ban\\u000a Treaty (CTBT) International Monitoring System. This work details the development of prompt gamma activation analysis for measuring\\u000a the diffusion rates of xenon

  7. NMR study of the dissolution of laser-polarized xenon

    Microsoft Academic Search

    P. Berthault; H. Desvaux

    2003-01-01

    :   NMR of laser-polarized xenon is used to probe the dissolution behaviour of the noble gas in different liquids. The dissolution\\u000a and self-relaxation rates are extracted via a macroscopic model, and comparison of the decay rate of the xenon magnetization in deuterated and non-deuterated solvent\\u000a pairs allows the determination of the pure dipole-dipole contribution to relaxation. A transient convective effect,

  8. Gas Hydrate Equilibrium Measurements for Multi-Component Gas Mixtures and Effect of Ionic Liquid Inhibitors

    E-print Network

    Othman, Enas Azhar

    2014-04-07

    reservoirs are located 80 km offshore, in the North Field, and the production of liquefied natural gas (LNG) depends on reliable flow from offshore wellheads to onshore processing facilities. Classical methods for inhibiting hydrate formation are used...

  9. Dynamics of xenon binding inside the hydrophobic cavity of pseudo-wild-type bacteriophage T4 lysozyme explored through xenon-based NMR spectroscopy.

    PubMed

    Desvaux, Hervé; Dubois, Lionel; Huber, Gaspard; Quillin, Michael L; Berthault, Patrick; Matthews, Brian W

    2005-08-24

    Wild-type bacteriophage T4 lysozyme contains a hydrophobic cavity with binding properties that have been extensively studied by X-ray crystallography and NMR. In the present study, the monitoring of 1H chemical shift variations under xenon pressure enables the determination of the noble gas binding constant (K = 60.2 M(-1)). Although the interaction site is highly localized, dipolar cross-relaxation effects between laser-polarized xenon and nearby protons (SPINOE) are rather poor. This is explained by the high value of the xenon-proton dipolar correlation time (0.8 ns), much longer than the previously reported values for xenon in medium-size proteins. This indicates that xenon is highly localized within the protein cavity, as confirmed by the large chemical shift difference between free and bound xenon. The exploitation of the xenon line width variation vs xenon pressure and protein concentration allows the extraction of the exchange correlation time between free and bound xenon. Comparison to the exchange experienced by protein protons indicates that the exchange between the open and closed conformations of T4 lysozyme is not required for xenon binding. PMID:16104744

  10. CO2 capture from simulated fuel gas mixtures using semiclathrate hydrates formed by quaternary ammonium salts.

    PubMed

    Park, Sungwon; Lee, Seungmin; Lee, Youngjun; Seo, Yongwon

    2013-07-01

    In order to investigate the feasibility of semiclathrate hydrate-based precombustion CO2 capture, thermodynamic, kinetic, and spectroscopic studies were undertaken on the semiclathrate hydrates formed from a fuel gas mixture of H2 (60%) + CO2 (40%) in the presence of quaternary ammonium salts (QASs) such as tetra-n-butylammonium bromide (TBAB) and fluoride (TBAF). The inclusion of QASs demonstrated significantly stabilized hydrate dissociation conditions. This effect was greater for TBAF than TBAB. However, due to the presence of dodecahedral cages that are partially filled with water molecules, TBAF showed a relatively lower gas uptake than TBAB. From the stability condition measurements and compositional analyses, it was found that with only one step of semiclathrate hydrate formation with the fuel gas mixture from the IGCC plants, 95% CO2 can be enriched in the semiclathrate hydrate phase at room temperature. The enclathration of both CO2 and H2 in the cages of the QAS semiclathrate hydrates and the structural transition that results from the inclusion of QASs were confirmed through Raman and (1)H NMR measurements. The experimental results obtained in this study provide the physicochemical background required for understanding selective partitioning and distributions of guest gases in the QAS semiclathrate hydrates and for investigating the feasibility of a semiclathrate hydrate-based precombustion CO2 capture process. PMID:23718261

  11. Rigorous solution to the extended kinetic equations for homogeneous gas mixtures

    NASA Astrophysics Data System (ADS)

    Spiga, Giampiero

    The paper deals with a recently introduced extended kinetic theory for gas mixtures. Such a generalization is aimed at accounting for effects of removal, generation and source, as well as for the presence of a background medium. These physical effects are modeled by suitable gain and loss terms into the set of Boltzmann equations governing the gas distribution functions. The outstanding work done for the search of exact or rigorous analytical solutions to the standard Boltzmann equation in the space homogeneous case and for Maxwell scattering models is reviewed. It is then shown how the previous results can be generalized to treat also gas mixtures in the extended version. In particular, in spite of the nonlinearities, a Fourier transform technique, with suitably defined generating functions, leads to a hierarchy of moment equations solvable in cascade, and a series reconstruction of the distribution functions, converging in an appropriate Hilbert space, follows then by resorting to a Bobylev transformation. Finally, the role played by the theory of dynamical systems in extended kinetic theory is discussed, and some examples of application are presented and commented on.

  12. Secondary scintillation yield in pure xenon

    NASA Astrophysics Data System (ADS)

    Monteiro, C. M. B.; Fernandes, L. M. P.; Lopes, J. A. M.; Coelho, L. C. C.; Veloso, J. F. C. A.; dos Santos, J. M. F.; Giboni, K.; Aprile, E.

    2007-05-01

    The xenon secondary scintillation yield was studied as a function of the electric field in the scintillation region, in a gas proportional scintillation counter operated at room temperature. A large area avalanche photodiode was used for the readout of the VUV secondary scintillation produced in the gas, together with the 5.9 keV x-rays directly absorbed in the photodiode. The latter was used as a reference for the determination of the number of charge carriers produced by the scintillation pulse and, thus, the number of VUV photons impinging the photodiode. A value of 140 photons/kV was obtained for the scintillation amplification parameter. The attained results are in good agreement with those predicted, for room temperature, by Monte Carlo simulation and Boltzmann calculations, as well as with those obtained for saturated xenon vapour, at cryogenic temperatures, and are about a factor of two higher than former results measured at room temperature.

  13. The incorporation and migration of a single xenon atom in ceria

    NASA Astrophysics Data System (ADS)

    Miao, Yinbin; Chen, Wei-Ying; Oaks, Aaron; Mo, Kun; Stubbins, James F.

    2014-06-01

    The behavior of xenon gas is crucial for the performance of nuclear fuel materials. We report molecular statics calculation results for the characteristics of a single xenon atom in cerium oxide, a non-radioactive surrogate of uranium dioxide. A variety of possible xenon incorporation sites, including the octahedral interstitial position, single-Ce-vacancy clusters, and double-Ce-vacancy clusters were considered. The binding energies and corresponding xenon incorporation energies were computed to reveal the preferred xenon positions in ceria. Different migration mechanisms of single xenon atoms were found to be involved with various incorporation sites. The energy barriers of all possible migration pathways were calculated. Only the mobility of single xenon atoms in the double-Ce-vacancy sites, which is due to the vacancy-assisted xenon migration, can account for the xenon diffusivity implied by bubble formation observed in experiments. The results also validated the role of ceria as a reliable surrogate of uranium dioxide in studies involving xenon gas.

  14. Adsorption of a binary gas mixture which laterally interacts on a random heterogeneous surface

    SciTech Connect

    Ritter, J.A.

    1992-01-01

    Analytical expressions for the adsorption of a binary gas mixture which laterally interacts on a heterogeneous surface are developed. The lateral interactions are of the Bragg-Williams type and the surface heterogeneity is modeled via a random distribution of sites described by a uniform distribution of Henry's Law constants. The parametric study shows that complex phase behavior can be predicted, including azeotropes and sigmoidal shaped X-Y diagrams. Also, this model may be useful for modeling and designing adsorption processes as it requires few iterations to simultaneously solve the implicit and coupled algebraic expressions.

  15. Asymptotic modelling of the axisymmetric flow of a binary gas mixture in a circular microchannel

    NASA Astrophysics Data System (ADS)

    Croizet, C.; Gatignol, R.

    2014-12-01

    In order to decrease the computation time, the development of asymptotic models describing gas flows in microchannels is an interesting alternative to DSMC simulations. In this contribution, our purpose is to model the axisymmetric flow of a mixture of two compressible gases in circular microchannels. The flow is in the slip regime that is at low Mach numbers and at low to moderate Knudsen numbers. The model is derived from Navier-Stokes equations and provides explicitly the longitudinal velocities in term of the pressures that are computed from a first order set of differential equations. The results are in good agreement with DSMC simulations.

  16. Lasing characteristics of gas mixtures involving UFG: Application to nuclear pumping of lasers

    NASA Technical Reports Server (NTRS)

    Verdeyen, J. T.; Eden, J. G.

    1980-01-01

    Intense blue-green fluorescence from a structured band centered at lambda approximately 484 nm was observed from Ar, CF3I and NF3 gas mixtures excited by an electron beam. This emission was tentatively assigned to the E yields A transition of the iodine monofluoride (IF) molecule. The fluorescence efficiency of the IF(E yields A) band and the IF (E) state radiative lifetime were estimated to be approximately 6% and 15 ns, respectively. The emission band structure, the short IF(E) radiative lifetime and the Franck-Condon shift between the E and A states suggest that IF is an attractive candidate for a blue-green laser.

  17. Variational principles and two-fluid hydrodynamics of bubbly liquid/gas mixtures

    NASA Astrophysics Data System (ADS)

    Geurst, J. A.

    1986-04-01

    In a recent paper the two-phase flow equations for a bubbly liquid/gas mixture were derived by variational methods. Starting point was an Euler form of Hamilton's extended principle of least action. The effect of the virtual mass of the gas bubbles was included. It is demonstrated now that a variational principle in the Langrange form yields the same two-fluid equations. In addition it is shown how the Lagrange form is trandformed in the Euler form by means of a canonical transformation. With regard to a recent discussion in the literature the material frame indifference or objectivity of the virtual-mass terms is investigated. The mutual force between the two-phases which is associated with the virtual mass of the gas bubbles turns out to be objective. In the limit of low bubble concentrations the results of the one-bubble theory are recovered. A corrected value is derived for the lift coefficient of a gas bubble in a rotational flow. It is indicated how a scheme of iterative solutions yields higher order approximations in which the mutual interaction of the gas bubbles is taken into account.

  18. Nuclear spin relaxation of {sup 129}Xe due to persistent xenon dimers

    SciTech Connect

    Berry-Pusey, B. N.; Anger, B. C.; Laicher, G.; Saam, B. [Department of Physics, University of Utah, Salt Lake City, Utah 84112-0830 (United States)

    2006-12-15

    We have measured longitudinal nuclear relaxation rates of {sup 129}Xe in Xe-N{sub 2} mixtures at densities below 0.5 amagats in a magnetic field of 8.0 T. We find that intrinsic spin relaxation in this regime is principally due to fluctuations in the intramolecular spin-rotation (SR) and chemical-shift-anisotropy (CSA) interactions, mediated by the formation of {sup 129}Xe-Xe persistent dimers. Our results are consistent with previous work done in one case at much lower applied fields where the CSA interaction is negligible and in another case at much higher gas densities where transient xenon dimers mediate the interactions. We have verified that a large applied field suppresses the persistent-dimer mechanism, consistent with standard relaxation theory, allowing us to measure room-temperature gas-phase relaxation times T{sub 1} for {sup 129}Xe greater than 25 h at 8.0 T. These data also yield a maximum possible low-field T{sub 1} for pure xenon gas at room temperature of 5.45{+-}0.2 h. The coupling strengths for the SR and CSA interactions that we extract are in fair agreement with estimates based both on previous experimental work and on ab initio calculations. Our results have potential implications for the production and storage of large quantities of hyperpolarized {sup 129}Xe for use in various applications.

  19. The Genesis solar xenon composition and its relationship to planetary xenon signatures

    NASA Astrophysics Data System (ADS)

    Crowther, S. A.; Gilmour, J. D.

    2013-12-01

    The fluence and isotopic composition of solar wind xenon have been determined from silicon collector targets flown on the NASA Genesis mission. A protocol was developed to extract gas quantitatively from samples of ?9-25 mm2, and xenon measured using the RELAX mass spectrometer. The fluence of implanted solar wind xenon is 1.202(87) × 106 atoms 132Xe cm-2, which equates to a flux of 5.14(21) × 106 atoms 132Xe cm-2 year-1 at the L1 point. This value is in good agreement with those reported in other studies. The isotopic composition of the solar wind is consistent with that extracted from the young lunar regolith and other Genesis collector targets. The more precise xenon isotopic data derived from the Genesis mission confirm models of relationships among planetary xenon signatures. The underlying composition of Xe-Q is mass fractionated solar wind; small, varying contributions of Xe-HL and 129Xe from 129I decay are present in reported meteorite analyses. In contrast, an s-process deficit is apparent in Xe-P3, which appears to have been mass fractionated to the same extent as Xe-Q from a precursor composition, suggesting similar trapping mechanisms. Solar wind xenon later evolved by the addition of ?1% (at 132Xe) of s-process xenon to this precursor. As an alternative model to a single source reservoir for Xe-P3, we propose that trapping of xenon onto carbonaceous carriers has been an ongoing process across galactic history, and that preparation of the residues in which Xe-P3 has been identified preferentially preserves longer lived host phases; a higher proportion of these sample xenon isotopic compositions from earlier in galactic chemical evolution, allowing the s-process deficit to become apparent. The relationships among SW-Xe, Xe-Q and Xe-P3 predict that the 124Xe/132Xe ratio for the solar wind is 0.00481(6).

  20. Growth of carbon nanotubes by microwave plasma chemical vapor deposition using CH 4 and CO 2 gas mixture

    Microsoft Academic Search

    M. Chen; Chieng-Ming Chen; Chia-Fu Chen

    2002-01-01

    Carbon nanotubes (CNTs) were grown vertically and aligned on Fe catalytic nanoparticles which were deposited on a Si substrate at low temperature using CH4 and CO2 gas mixtures. A dynamic form of optical emission spectroscopy was used to detect the species in the plasma. These data show the dominant species in gas phase reaction. The composition of plasma significantly affects

  1. Nuclear Instruments and Methods in Physics Research A 526 (2004) 409412 GEM operation in negative ion drift gas mixtures

    E-print Network

    2004-01-01

    elements in negative ion gas mixtures is reported. Gains up to several thousand were obtained from single. Negative ion drift gases (NI-gases) are another innovation in gas detector technology which are just or TPC device to be transported to the gain elements in the form of negative molecular ions [10

  2. Light yield measurements of GEM avalanches at cryogenic temperatures and high densities in neon based gas mixtures

    Microsoft Academic Search

    R. Galea; J. Dodd; W. Willis; P. Rehak; V. Tcherniatine

    2007-01-01

    Gas Electron Multipliers (GEM) are being used in the baseline readout design of a cryogenic Time Projection Chamber (TPC). The GEMs provide amplification of an ionization charge signal but rather than reading out the charge signal, the proportional light produced in the GEM avalanche will be imaged using commercially available low-noise CCD cameras. Our measurements of neon-based gas mixtures at

  3. Direct measurement of the electron density in electron beam irradiated Ar\\/HCl gas mixtures by time-resolved interferometry

    Microsoft Academic Search

    M. Lando; Z. Rozenberg; M. Rokni

    1990-01-01

    The electron density in electron-beam irradiated Ar\\/HCl gas mixtures has been measured by time-resolved infrared interferometry at 9.6 ?m, using a Mach-Zehnder interferometer. Measurements were performed for e-beam irradiated gas mixtures with various HCl concentrations between 0.05% and 5.0%, and total gas pressures between 0.5 and 4.0 atm. The e-beam pulse was 350 ns long and at an energy of

  4. Transport Properties of He-N2 Binary Gas Mixtures for CBC Space Applications

    NASA Astrophysics Data System (ADS)

    Tournier, Jean-Michel P.; El-Genk, Mohamed S.

    2008-01-01

    In order to reduce the size and mass of the single-shaft turbo-machines, with little impact on the size of the heat transfer components in the CBC loop, He-Xe binary mixture with a molecular weight of 40 g/mole has been the working fluid of choice in space nuclear reactor power systems with Close Brayton Cycle (CBC) for energy conversion. This working fluid is also a suitable coolant for the fission reactors heat source designed with fast neutron energy spectra. For space nuclear reactors with thermal neutron energy spectra, however, the high capture neutron cross-section of Xe will reduce the beginning-of-life excess reactivity of the reactor, decreasing its effective operation lifetime. In addition, the neutron activation of Xe in the reactor will introduce a radioactivity source term in the CBC loop. Alternative working fluids with no activation concerns and comparable performance are N2 and the binary mixtures of He-N2. This paper calculates the transport properties of these working fluids and compares their values to those of noble gas binary mixtures at the temperatures and pressures expected in CBC space reactor power system applications. Also investigated is the impact of using these working fluids on the pressure losses, heat transfer coefficient, and the aerodynamic loading of the blades in the CBC turbo-machines.

  5. Radon removal from gaseous xenon with activated charcoal

    NASA Astrophysics Data System (ADS)

    Abe, K.; Hieda, K.; Hiraide, K.; Hirano, S.; Kishimoto, Y.; Kobayashi, K.; Koshio, Y.; Liu, J.; Martens, K.; Moriyama, S.; Nakahata, M.; Nishiie, H.; Ogawa, H.; Sekiya, H.; Shinozaki, A.; Suzuki, Y.; Takachio, O.; Takeda, A.; Ueshima, K.; Umemoto, D.; Yamashita, M.; Hosokawa, K.; Murata, A.; Otsuka, K.; Takeuchi, Y.; Kusaba, F.; Motoki, D.; Nishijima, K.; Tasaka, S.; Fujii, K.; Murayama, I.; Nakamura, S.; Fukuda, Y.; Itow, Y.; Masuda, K.; Nishitani, Y.; Takiya, H.; Uchida, H.; Kim, Y. D.; Kim, Y. H.; Lee, K. B.; Lee, M. K.; Lee, J. S.; Xmass Collaboration

    2012-01-01

    Many low background experiments using xenon need to remove radioactive radon to improve their sensitivities. However, no method of continually removing radon from xenon has been described in the literature. We studied a method to remove radon from xenon gas through an activated charcoal trap. From our measurements we infer a linear relationship between the mean propagation velocity vRn of radon and vXe of xenon in the trap with vRn/vXe=(0.96±0.10)×10-3 at -85 °C. As the mechanism for radon removal in this charcoal trap is its decay, knowledge of this parameter allows us to design an efficient radon removal system for the XMASS experiment. The verification of this system found that it reduces radon by a factor of 0.07, which is in line with its expected average retention time of 14.8 days for radon.

  6. Modeling of the pressurized xenon gamma ray scintillation detector

    NASA Astrophysics Data System (ADS)

    Meek, Romney; Barzilov, Alexander; Novikov, Ivan

    2011-10-01

    We are developing a high pressure xenon detector for photon measurements. Xenon produces electroluminescence (EL) scintillation emission that we use as the primary signal in our strategy to acquire information. The detector consists of a high pressure chamber, a thin radiation input window with the supporting grid of collimator ribs and electrode grids to create the electric field, and a photo sensor -- the large area silicon avalanche photodiode. The electrode grids are made of thin wire. The modeling of the electric field is a crucial step in developing a working prototype. It has been previously shown that the uniform electric field divided by the number density of xenon gas needs to be above approximately 3 Td to give enough energy to ionize the xenon atoms, but less than 16 Td to prevent electron avalanches from occurring. The electric field was modeled using Comsol Multiphysics. This presentation discusses the results of electric field modeling for the detector (absorption, drift, and EL regions).

  7. High-accuracy P-p-T measurements of pure gas and natural gas like mixtures using a compact magnetic suspension densimeter 

    E-print Network

    Ejaz, Saquib

    2007-09-17

    to produce gas from deep and ultra-deepwater of the Gulf of Mexico where the pressures and temperatures encountered are much higher. Produced gas mixtures have compositions containing higher percentages of the C6+ fraction. As AGA8-DC92 is a statistical fit...

  8. Laser induced avalanche ionization in gases or gas mixtures with resonantly enhanced multiphoton ionization or femtosecond laser pulse pre-ionization

    SciTech Connect

    Shneider, Mikhail N.; Miles, Richard B. [Applied Physics Group, MAE Department, Princeton University, Princeton, New Jersey 08544 (United States)

    2012-08-15

    The paper discusses the requirements for avalanche ionization in gas or gas mixtures initiated by REMPI or femtosecond-laser pre-ionization. Numerical examples of dependencies on partial composition for Ar:Xe gas mixture with REMPI of argon and subsequent classic avalanche ionization of Xe are presented.

  9. Premixed mixture ignition in the end-gas region (PREMIER) combustion in a natural gas dual-fuel engine: operating range and exhaust emissions

    Microsoft Academic Search

    U Azimov; E Tomita; N Kawahara; Y Harada

    2011-01-01

    This paper is concerned with engine experiments and spectroscopic analysis of premixed mixture ignition in the end-gas region (PREMIER) combustion in a pilot fuel ignited, natural gas dual-fuel engine. The results reveal the characteristics and operating parameters that induce and affect this combustion mode. The PREMIER combustion is followed by natural gas flame propagation. Pilot-injected diesel fuel ignites the natural

  10. Emissions in combustion of lean methane-air and biomass-air mixtures supported by primary hot burned gas in a multi-stage gas turbine combustor

    Microsoft Academic Search

    Sadamasa Adachi; Atushi Iwamoto; Shigeru Hayashi; Hideshi Yamada; Shigehiko Kaneko

    2007-01-01

    Thermal reaction of lean to ultra-lean premixed mixtures supported by the hot burned gas from the up-stream stage can be used for obtaining a better trade-off between ultra-low-NOx and high combustion efficiency over a wide range of operations of a gas turbine. A three-stage model combustor designed based on this concept is being developed for a biomass gas-fueled regenerative cycle

  11. High-power atomic xenon laser

    NASA Astrophysics Data System (ADS)

    Witteman, Wilhelmus J.; Peters, Peter J. M.; Botma, Hako; Tskhai, S. N.; Udalov, Yuri B.; Mei, Qi-Chu; Ochkin, V. N.

    1995-03-01

    The high pressure atomic xenon laser is becoming the most promising light source in the wavelength region of a few microns. The merits are high efficiency (so far up to 8 percent), high output energies (15 J/liter at 9 bar), high continuous output power (more than 200 W/liter), no gas dissociation and thermal heating of the lower laser level. Compared with the well-known low pressure xenon laser the power performance is now roughly a factor thousand higher. The operation of the system, based on three-body-collisions, uses the metastable state of the xenon atom as the ground state so that in the recirculation of energy a high quantum efficiency is obtained. Furthermore the homogeneous line broadening caused by the high collision frequency has also a strong beneficial effect on the efficiency. However, the required intense homogeneous excitation of the gas medium at high density is from a technical point of view a great challenge. From our experimental and theoretical work we found that at optimum performance the input power must be 1 to 2.5 [KW cm-3 atm-2]. We describe our results obtained with e-beam sustained and x-ray preionized systems delivering pulsed energies in the range of joules per liter. Furthermore we describe our recent results on continuous RF excited wave guide systems of about 37 cm length with output powers in the range of watts.

  12. Effect of mixture ratios and nitrogen carrier gas flow rates on the morphology of carbon nanotube structures grown by CVD

    Microsoft Academic Search

    Gerald Franky Malgas; Christopher J. Arendse; Nonhlanhla P. Cele; Franscious R. Cummings

    2008-01-01

    We report on the growth of carbon nanotubes (CNTs) by thermal Chemical Vapor Deposition (CVD) and investigate the effects\\u000a of nitrogen carrier gas flow rates and mixture ratios on the morphology of CNTs on a silicon substrate by vaporizing the camphor\\/ferrocene\\u000a mixture at 750 °C in a nitrogen atmosphere. Carbon layers obtained after each CVD growth run of 15 min are characterized

  13. Viscosity and Thermal Conductivity of Binary Gas Mixtures: Argon-Neon, Argon-Helium, and Neon-Helium

    Microsoft Academic Search

    E. Thornton; W. A. D. Baker

    1962-01-01

    The coefficients of viscosity and thermal conductivity of the binary gas mixtures argon-neon, argon-helium and neon-helium, have been determined over the full range of composition of each mixture at a pressure of 70 cm of mercury and at a temperature in the range 18.0 to 18.3 °C. The experimental values are compared with theoretical values based on the Lennard-Jones (6-12)

  14. Influence of gas temperature on self-sustained volume discharge characteristics in working mixtures of a repetitively pulsed COIL

    NASA Astrophysics Data System (ADS)

    Aksinin, V. I.; Antsiferov, S. A.; Velikanov, S. D.; Kazantsev, S. Yu; Kalinovskii, V. V.; Konovalov, V. V.; Kononov, I. G.; Mikhalkin, V. N.; Podlesnykh, S. V.; Sevryugin, I. V.; Firsov, K. N.

    2014-02-01

    The influence of gas temperature on the characteristics of a self-sustained volume discharge was studied in the working mixtures of a chemical oxygen - iodine laser with pulsed electricdischarge production of iodine atoms. In experiments, laser working mixtures were modelled by the mixture of air and iodide C2H5I. It was established that mixture heating is accompanied by an increase in the voltage across the discharge plasma and by a decrease in the discharge current. By varying the temperature of the mixture with the iodine content of ~2.7% and initial pressure p=12 Torr from 22 °C to 96 °C, the current amplitude falls by ~12%, and at the instant corresponding to a maximal current the voltage raises by ~22%. Such a change in the discharge characteristics is explained by a higher rate of electron attachment to vibrationally excited iodide molecules at elevated temperatures.

  15. Limiting field strength and electron swarm coefficients of the CF3I-SF6 gas mixture

    NASA Astrophysics Data System (ADS)

    de Urquijo, J.; Mitrani, A.; Ruíz-Vargas, G.; Basurto, E.

    2011-08-01

    We have measured the electron drift velocity, longitudinal diffusion, and the effective ionization coefficients in the gaseous mixture of CF3I-SF6 over the density-normalized electric field intensity E/N, from 375 to 500 Td (1 Td = 10-17 V cm2). A pulsed Townsend technique was used. Overall, the gas mixture compositions were varied from 50 to 90% CF3I. We have found that the limiting field strength E/Nlim of the CF3I-SF6 mixture is superior to that of CF3I-N2, and always higher than that of SF6. Moreover, over the whole mixture range, the range of the limiting field strength for the CF3I-SF6 mixture is 360-437 Td, these limits corresponding for pure SF6 and CF3I, respectively.

  16. NMR investigations of gas transport in fluidized beds

    Microsoft Academic Search

    R. Wang; J. Ng; M. Rosen; R. Mair; R. Walsworth; D. Candela

    2004-01-01

    We are using NMR of hyperpolarized xenon to study gas transport in fluidized beds. Our preliminary investigations have shown that both the xenon NMR frequency and linewidth are dependent on the bulk gas flow rate through the bed; and that a distinct xenon NMR frequency spectral peak can be observed in the bubbling regime. These changes of the xenon NMR

  17. On the operation of a micropattern gaseous UV-photomultiplier in liquid-Xenon

    NASA Astrophysics Data System (ADS)

    Duval, S.; Breskin, A.; Budnik, R.; Chen, W. T.; Carduner, H.; Cortesi, M.; Cussonneau, J. P.; Donnard, J.; Lamblin, J.; Le Ray, P.; Morteau, E.; Oger, T.; Stutzmann, J. S.; Thers, D.

    2011-04-01

    Operation results are presented of a UV-sensitive gaseous photomultiplier (GPM) coupled through a MgF2 window to a liquid-xenon scintillator. It consisted of a reflective CsI photocathode deposited on top of a THick Gaseous Electron Multiplier (THGEM); further multiplication stages were either a second THGEM or a Parallel Ionization Multiplier (PIM) followed by a MICROMEsh GAseous Structure (MICROMEGAS). The GPM operated in gas-flow mode with non-condensable gas mixtures. Gains of 104 were measured with a CsI-coated double-THGEM detector in Ne/CH4(95:5), Ne/CF4(95:5) and Ne/CH4/CF4 (90:5:5), with soft X-rays at 173 K. Scintillation signals induced by alpha particles in liquid xenon were measured here for the first time with a double-THGEM GPM in He/CH4(92.5:7.5) and a triple-structure THGEM/PIM/MICROMEGAS GPM in Ne/CH4(90:10) with a fast-current preamplifier.

  18. Deactivation of the xenon atom in the 6s metastable state in collisions with xenon and helium atoms

    Microsoft Academic Search

    D A Zayarnyi; Ludmila V Semenova; N N Ustinovskii; I V Kholin; A Yu Chugunov

    1998-01-01

    The absorption probing method was used to investigate collisional deactivation of the metastable 6s[3\\/2]°(³P) state of the xenon atom in high-pressure He - Xe mixtures with a low xenon concentration. Measurements were made of the rate constants of the plasma-chemical reactions Xe*+Xe+He Xe*+He [(1.7 {+-}0.2) x10³² cm s¹], Xe*+2He HeXe*+He (less than 3 x 10³ cm s¹), and Xe*+He products+He

  19. ACTIVE MEDIA: Deactivation of the xenon atom in the 6s metastable state in collisions with xenon and helium atoms

    Microsoft Academic Search

    D. A. Zayarnyi; Ludmila V. Semenova; N. N. Ustinovskii; I. V. Kholin; A. Yu Chugunov

    1998-01-01

    The absorption probing method was used to investigate collisional deactivation of the metastable 6s[3\\/2]20(3P2) state of the xenon atom in high-pressure He --- Xe mixtures with a low xenon concentration. Measurements were made of the rate constants of the plasma-chemical reactions Xe*+Xe+He --> Xe2*+He [(1.7 ±0.2) ×10-32 cm6 s-1], Xe*+2He--> HeXe*+He (less than 3 × 10-35 cm6 s-1), and Xe*+He-->

  20. Effect Of Gas Mixture Composition On Tar Removal Process In A Pulsed Corona Discharge Reactor

    NASA Astrophysics Data System (ADS)

    Filimonova E.; Naidis, G.

    2010-07-01

    The simulation of naphthalene (C10H8) removal from several gas mixtures (pure nitrogen, mixtures containing N2 with CO2, CO, H2, H2O, and biogas - the product of biomass gasification), has been investigated. The modeling is based on the experimental data obtained in the reactor with a pulsed positive corona discharge. The problem of simulation of the cleaning process includes description of two stages. The first, fast stage is generation of primary active species during streamer propagation. The second, slow stage is the chain of chemical transformations triggered by these species. The input parameters for the modeling of the second stage are G-values for generation of primary active species, obtained under consideration of streamer dynamics. Simulation of the second stage of the removal process takes into account the processes of chemical kinetics and diffusion outside and inside of streamer traces during multi-pulsed treatment. Besides neutral active species, streamer discharges produce electrons and ions. Primary positive ions (N2+, CO+, CO2+, H2+, H2O+) in a chain of fast ion-molecule reactions transform into more stable positive ions. The ions recombine with electrons. Both ion-molecule reactions and electron-ion recombination process are additional (to dissociation of gas molecules by electron impact in the streamer head) sources of neutral active species. The relative contribution of these sources to the G-values for H, OH and O is rather large. In our modeling two approaches have been used. At the first approach the contribution of ion-molecule reactions is estimated approximately assuming that the dominating stable ion is N4+ (in pure N2 and its mixtures with H2) or CO2+ (in mixtures including CO2). Other way is the calculations with kinetic scheme including the molecular ions, aquated ions such as H3O(H2O)m+, NO2(H2O)-, NO2(H2O)+ and other. The comparison of results of two approaches is presented. Only full kinetic scheme allowed describing the experimental results for 82.5%N2+17.5%H2O mixture on C10H8 removal. Obtained dependencies of the remaining naphthalene fraction versus the specific energy input have been compared with the experimental data. The results agree rather well for considered mixtures. The best decomposition has been obtained in nitrogen with water vapor, a little better than that in pure nitrogen, both in experiments and in the simulation. It has been found that the reaction of naphthalene with excited nitrogen molecules N2(A3S) plays a key role in the removal process. Addition to N2 of such gases as CO, CO2 and H2 reduces the removal efficiency noticeably.

  1. Fast gas heating in N2/O2 mixtures under nanosecond surface dielectric barrier discharge: the effects of gas pressure and composition.

    PubMed

    Nudnova, M M; Kindysheva, S V; Aleksandrov, N L; Starikovskii, A Yu

    2015-08-13

    The fractional electron power quickly transferred to heat in non-equilibrium plasmas was studied experimentally and theoretically in N2/O2 mixtures subjected to high electric fields. Measurements were performed in and after a nanosecond surface dielectric barrier discharge at various (300-750 Torr) gas pressures and (50-100%) N2 percentages. Observations showed that the efficiency of fast gas heating is almost independent of pressure and becomes more profound when the fraction of O2 in N2/O2 mixtures increases. The processes that contribute towards the fast transfer of electron energy to thermal energy were numerically simulated under the conditions considered. Calculations were compared with measurements and the main channels of fast gas heating were analysed at the gas pressures, compositions and electric fields under study. It was shown that efficient fast gas heating in the mixtures with high fraction of O2 is due to a notable contribution of heat release during quenching of electronically excited N2 states in collisions with O2 molecules and to ion-ion recombination. The effect of hydrocarbon addition to air on fast gas heating was numerically estimated. It was concluded that the fractional electron power transferred to heat in air, as a first approximation, could be used to estimate this effect in lean and stoichiometric hydrocarbon-air mixtures. PMID:26170431

  2. Obtaining the cumulative k-distribution of a gas mixture from those of its components. [radiative transfer in stratosphere

    NASA Technical Reports Server (NTRS)

    Gerstell, M. F.

    1993-01-01

    A review of the convolution theorem for obtaining the cumulative k-distribution of a gas mixture proven in Goody et al. (1989) and a discussion of its application to natural spectra are presented. Computational optimizations for use in analyzing high-altitude gas mixtures are introduced. Comparisons of the results of the optimizations, and criteria for deciding what altitudes are 'high' in this context are given. A few relevant features of the testing support software are examined. Some spectrally integrated results, and the circumstances the might permit substituting the method of principal absorbers are examined.

  3. The effect of pore dimension of zeolites on the separation of gas mixtures

    NASA Astrophysics Data System (ADS)

    Jee, Sang Eun

    We examined the effect of the pore dimension of zeolites on the separation of gas mixtures using atomistic simulation methods. We studied two categories of the zeolites with small pores: pore modified silicalite for H2/CH4 separation and small pore silica zeolites for CO2/CH4 separation. The effect of pore modification of silicalite on the H2/CH4 separation was examined. Under some degrees of surface modification, the CH4 flux was reduced much more than the H2 flux, resulting in high ideal selectivities. The use of small pore zeolites for CO2/CH4 separations was studied. In DDR, we showed that CO2 diffusion rates are only weakly affected by the presence of CH4, even though the latter molecules diffuse very slowly. Consequently, therefore, the permeance of CO 2 in the equimolar mixtures is similar to the permeance for pure CO 2, while the CH4 permeance in the mixture is greatly reduced relatively to the pure component permeance. The calculated CO2/CH 4 separation selectivities are higher than 100 for a wide range of feed pressure, indicating excellent separation capabilities of DDR based membranes. Inspired by the observation in DDR we also examined the separation capabilities of 10 additional pure silica small pore zeolites for CO2/CH 4 separations. From these considerations, we predict that SAS, MTF and RWR will exhibit high separation selectivities because of their very high adsorption selectivities for CO2 over CH4. CHA and IHW, which have similar pore structures to DDR, showed comparable separation selectivities to DDR because of large differences in the diffusion rates of CO2 and CH4.

  4. Multiproperty empirical isotropic interatomic potentials for CH4-inert gas mixtures.

    PubMed

    El-Kader, M S A

    2013-11-01

    An approximate empirical isotropic interatomic potentials for CH4-inert gas mixtures are developed by simultaneously fitting the Exponential-Spline-Morse-Spline-van der Waals (ESMSV) potential form to viscosity, thermal conductivity, thermal diffusion factors, diffusion coefficient, interaction second pressure virial coefficient and scattering cross-section data. Quantum mechanical lineshapes of collision-induced absorption (CIA) at different temperatures for CH4-He and at T = 87 K for CH4-Ar are computed using theoretical values for overlap, octopole and hexadecapole mechanisms and interaction potential as input. Also, the quantum mechanical lineshapes of collision-induced light scattering (CILS) for the mixtures CH4-Ar and CH4-Xe at room temperature are calculated. The spectra of scattering consist essentially of an intense, purely translational component which includes scattering due to free pairs and bound dimers, and the other is due to the induced rotational scattering. These spectra have been interpreted by means of pair-polarizability terms, which arise from a long-range dipole-induced-dipole (DID) with small dispersion corrections and a short-range interaction mechanism involving higher-order dipole-quadrupole A and dipole-octopole E multipole polarizabilities. Good agreement between computed and experimental lineshapes of both absorption and scattering is obtained when the models of potential, interaction-induced dipole and polarizability components are used. PMID:25685458

  5. Enhanced technique for measuring collisional quenching rate coefficients in rare-gas mixtures

    NASA Astrophysics Data System (ADS)

    Zayarnyi, D. A.; L'dov, A. Yu; Kholin, I. V.

    2011-02-01

    We set forth an improved technique for the investigation of collisional quenching in high-pressure rare-gas mixtures, which relies on the absorption probing measurements of the decay rates of the excited states of these gases in the afterglow of a fast electron beam discharge. We determined more precisely the rate coefficients of the plasmochemical reactions Xe* + Xe + Ar ? Xe2* and Xe*+Ar ? products + Ar for the metastable (6s[3/2]20) and resonance (6s[3/2]10) levels of atomic Xe investigated in our earlier work. The rate coefficients for the reactions Xe(6s[3/2]20) + 2Ar ? ArXe* + Ar((7.2±1.4)×10-36 cm6 s-1) and Xe(6s[3/2]10) + 2Ar ? ArXe*((5.3±2.4)×10-36 cm6 s-1) were measured for the first time.

  6. Bronchial imaging in humans using xenon K-edge dichromography

    NASA Astrophysics Data System (ADS)

    Giacomini, J. C.; Gordon, H.; O'Neil, R.; Van Kessel, A.; Cason, B.; Chapman, D.; Lavendar, W.; Gmur, N.; Menk, R.; Thomlinson, W.; Zhong, Z.; Rubenstein, E.

    1998-02-01

    This report describes the initial use of K-edge xenon dichromography for imaging the bronchial tree in humans. The subjects inhale an anatomic dead-space volume of a mixture of 80% xenon and 20% oxygen, following which a dichromographic line-scan image is recorded using two monochromatic synchrotron radiation beams closely bracketing the k-edge of xenon (34.56 keV). Images of airways, from main-stem bronchi to fourth-order branches, are recorded with a pixel resolution of 0.5×0.5 mm. The scanning rate is 12 cm/s, the line exposure time is 4 ms, the skin dose to the exposed area (125 mm × 150 mm) is <0.35 rad.

  7. Shear Thinning in Xenon

    NASA Technical Reports Server (NTRS)

    Bergm Robert F.; Moldover, Michael R.; Yao, Minwu; Zimmerli, Gregory A.

    2009-01-01

    We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids such as molten plastics or ketchup, near the critical point of xenon. The data span a wide range of dimensionless shear rate: the product of the shear rate and the relaxation time of critical fluctuations was greater than 0.001 and was less than 700. As predicted by theory, shear thinning occurred when this product was greater than 1. The measurements were conducted aboard the Space Shuttle Columbia to avoid the density stratification caused by Earth's gravity.

  8. Detection of a CO and NH3 gas mixture using carboxylic acid-functionalized single-walled carbon nanotubes

    PubMed Central

    2013-01-01

    Carbon nanotubes (CNT) are extremely sensitive to environmental gases. However, detection of mixture gas is still a challenge. Here, we report that 10 ppm of carbon monoxide (CO) and ammonia (NH3) can be electrically detected using a carboxylic acid-functionalized single-walled carbon nanotubes (C-SWCNT). CO and NH3 gases were mixed carefully with the same concentrations of 10 ppm. Our sensor showed faster response to the CO gas than the NH3 gas. The sensing properties and effect of carboxylic acid group were demonstrated, and C-SWCNT sensors with good repeatability and fast responses over a range of concentrations may be used as a simple and effective detection method of CO and NH3 mixture gas. PMID:23286690

  9. Enantiospecific Chemical Mixture Analysis via Microwave Spectroscopy of Buffer Gas Cooled Samples

    NASA Astrophysics Data System (ADS)

    Patterson, David; Schnell, Melanie; Doyle, John

    2013-05-01

    We present experimental results demonstrating a sensitive, highly specific chemical analyzer via Fourier transform microwave (FTMW) spectroscopy of molecular samples cooled via buffer gas cooling to about 7 K. Room temperature spectroscopic methods are routinely used to identify and quantify small and medium sized molecules. These methods fail for larger molecules, which at room temperature occupy hundreds of thousands of ro-vibrational states, leading to broad spectral features composed of a large number of weak, unresolved lines. In contrast, samples cooled to a few degrees K exhibit qualitatively simpler spectra, composed of many fewer and much stronger resolvable, narrow lines. Here we show that a continuous, cold buffer gas cooled source provides an attractive source for a spectroscopy based chemical mixture analyzer. In addition, we will present novel extensions to FTMW which render it sensitive to the chirality of the analyte. In this work, opposite enantiomers are distinguished via a change in the phase of the emitted microwave radiation. This technique provides a robust, general, chirally sensitive chemical analyzer, and is the first demonstration of microwave spectroscopy applied to chiral analysis.

  10. Quantifying the impact of nitric oxide calibration gas mixture oxidation on reported nitrogen dioxide concentrations

    NASA Astrophysics Data System (ADS)

    Sweeney, Bryan P.; Quincey, Paul G.; Green, David; Fuller, Gary W.

    2015-03-01

    Chemiluminescent analysers for measuring nitric oxide (NO) and nitrogen dioxide (NO2) in ambient air are generally calibrated with certified gas standard cylinders of NO in nitrogen. Verification of the NOx and NO amount fractions has been carried out on many such 'on-site' calibration cylinders at air quality monitoring stations. These measurements indicate that significant numbers of these gas mixtures have become somewhat degraded, with several percent of the NO oxidised to NO2. The effect of not compensating for this degradation on reported concentrations is discussed. If such degradation is not quantified and corrected for, there will be a systematic under-reporting of NO2 concentrations, which, due to the non-linearity of the effect, could reduce high reported NO2 concentrations at kerbside sites by around 20%. This could significantly reduce the number of reported exceedances of the NO2 limit value at such sites, compared to results obtained where there is no degradation of the NO cylinder.

  11. Fabrication of micromechanical structures in silicon using SF6/O2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Paul, Ashok K.; Dimri, Askok K.; Mohan, S.

    1999-11-01

    Plasma etching has been used for the fabrication of micromechanical structures in silicon with fine feature size. In this paper, reactive ion etching (RIE) is used for micromachining applications in two steps, first for etching of SiO2 layer and then machining of silicon. The first RIE step is for the patterning of the SiO2 layer using photo-resist as mask. This process involves the use of gas mixture of CHF3 and Ar. The photo-resist is then removed in the oxygen plasma. The second step is to delineate the patterned SiO2 layer onto the silicon wafer using SF6/O2 plasma. The oxygen flow is varied from 2-10 sccm in SF6. Silicon etch rates of 195 nm/min and Si/SiO2 selectivity of 10:1 has been obtained. The process parameters such as gas flow, rf-power and etch pressure are optimized as per our reactor's configuration to have compromise for best selectivity, anisotropy, and high etch rates. A pattern transfer with nearly vertical walls is obtained for RIE based on SF6/O2/CHF3 while maintaining the substrate at low temperature.

  12. Mie scattering from submicron-sized CO2 clusters formed in a supersonic expansion of a gas mixture.

    PubMed

    Jinno, S; Fukuda, Y; Sakaki, H; Yogo, A; Kanasaki, M; Kondo, K; Faenov, A Ya; Skobelev, I Yu; Pikuz, T A; Boldarev, A S; Gasilov, V A

    2013-09-01

    A detailed mathematical model is presented for a submicron-sized cluster formation in a binary gas mixture flowing through a three-staged conical nozzle. By measuring the angular distribution of light scattered from the clusters, the size of CO(2) clusters, produced in a supersonic expansion of the mixture gas of CO(2)(30%)/H(2)(70%) or CO(2)(10%)/He(90%), has been evaluated using the Mie scattering method. The mean sizes of CO(2) clusters are estimated to be 0.28 ± 0.03 ?m for CO(2)/H(2) and 0.26 ± 0.04 ?m for CO(2)/He, respectively. In addition, total gas density profiles in radial direction of the gas jet, measuring the phase shift of the light passing through the target by utilizing an interferometer, are found to be agreed with the numerical modeling within a factor of two. The dryness (= monomer/(monomer + cluster) ratio) in the targets is found to support the numerical modeling. The apparatus developed to evaluate the cluster-gas targets proved that our mathematical model of cluster formation is reliable enough for the binary gas mixture. PMID:24103939

  13. Development of a Binary Mixture Gas Composition Instrument for Use in a Confined High Temperature Environment

    NASA Astrophysics Data System (ADS)

    Cadell, Seth R.

    With recent advancements in material science, industrial operations are being conducted at higher and higher temperatures. This is apparent in the nuclear industry where a division of the field is working to develop the High Temperature Gas Reactor and the Very High Temperature Gas Reactor concurrently. Both of these facilities will have outlet gas temperatures that are at significantly higher temperatures than the typical water cooled reactor. These increased temperatures provide improved efficiency for the production of hydrogen, provide direct heating for oil refineries, or more efficient electricity generation. As high temperature operations are being developed, instruments capable of measuring the operating parameters must be developed concurrently. Within the gas reactor community there is a need to measure the impurities within the primary coolant. Current devices will not survive the temperature and radiation environments of a nuclear reactor. An instrument is needed to measure the impurities within the coolant while living inside the reactor, where this instrument would measure the amount of the impurity within the coolant. There are many industrial applications that need to measure the ratio of two components, whether it be the amount of particulate in air that is typical to pneumatic pumping, or the liquid to gas ratio in natural gas as it flows through a pipeline. All of the measurements in these applications can be met using a capacitance sensor. Current capacitance sensors are built to operate at ambient temperatures with only one company producing a product that will handle a temperature of up to 400 °C. This maximum operating temperature is much too low to measure the gas characteristics in the High Temperature Gas Reactor. If this measurement technique were to be improved to operate at the expected temperatures, the coolant within the primary loop could be monitored for water leaks in the steam generator, carbon dust buildup entrained in the flow, or used to measure the purity of the coolant itself. This work details the efforts conducted to develop such an instrument. While the concept of designing a capacitance sensor to measure a gas mixture is not unique, the application of using a capacitance sensor within a nuclear reactor is a new application. This application requires the development of an instrument that will survive a high temperature nuclear reactor environment and operate at a sensitivity not found in current applications. To prove this technique, instrument prototypes were built and tested in confined environments and at high temperatures. This work discusses the proof of concept testing and outlines an application in the High Temperature Test Facility to increase the operational understanding of the instrument. This work is the first step toward the ultimate outcome of this work, which is to provide a new tool to the gas reactor community allowing real-time measurements of coolant properties within the core.

  14. Viewing inside Pyroclastic Flows - Large-scale Experiments on hot pyroclast-gas mixture flows

    NASA Astrophysics Data System (ADS)

    Breard, E. C.; Lube, G.; Cronin, S. J.; Jones, J.

    2014-12-01

    Pyroclastic density currents are the largest threat from volcanoes. Direct observations of natural flows are persistently prevented because of their violence and remain limited to broad estimates of bulk flow behaviour. The Pyroclastic Flow Generator - a large-scale experimental facility to synthesize hot gas-particle mixture flows scaled to pyroclastic flows and surges - allows investigating the physical processes behind PDC behaviour in safety. The ability to simulate natural eruption conditions and to view and measure inside the hot flows allows deriving validation and calibration data sets for existing numerical models, and to improve the constitutive relationships necessary for their effective use as powerful tools in hazard assessment. We here report on a systematic series of large-scale experiments on up to 30 ms-1 fast, 2-4.5 m thick, 20-35 m long flows of natural pyroclastic material and gas. We will show high-speed movies and non-invasive sensor data that detail the internal structure of the analogue pyroclastic flows. The experimental PDCs are synthesized by the controlled 'eruption column collapse' of variably diluted suspensions into an instrumented channel. Experiments show four flow phases: mixture acceleration and dilution during free fall; impact and lateral blasting; PDC runout; and co-ignimbrite cloud formation. The fully turbulent flows reach Reynolds number up to 107 and depositional facies similar to natural deposits. In the PDC runout phase, the shear flows develop a four-partite structure from top to base: a fully turbulent, strongly density-stratified ash cloud with average particle concentrations <<1vol%; a transient, turbulent dense suspension region with particle concentrations between 1 and 10 vol%; a non-turbulent, aerated and highly mobile dense underflows with particle concentrations between 40 and 50 vol%; and a vertically aggrading bed of static material. We characterise these regions and the exchanges of energy and momentum through their interfaces via vertical time-series profiles of velocity, particle concentration, gas and particle transport directionality and turbulent eddy characteristics. We highlight the importance of each region for the PDC runout dynamics and introduce a new transport and sedimentation model for downslope evolving pyroclastic flows.

  15. Start-up, performance and optimization of a compost biofilter treating gas-phase mixture of benzene and toluene.

    PubMed

    Rene, Eldon R; Kar, Saurajyoti; Krishnan, Jagannathan; Pakshirajan, K; López, M Estefanía; Murthy, D V S; Swaminathan, T

    2015-08-01

    The performance of a compost biofilter inoculated with mixed microbial consortium was optimized for treating a gas-phase mixture of benzene and toluene. The biofilter was acclimated to these VOCs for a period of ?18d. The effects of concentration and flow rate on the removal efficiency (RE) and elimination capacity (EC) were investigated by varying the inlet concentration of benzene (0.12-0.95g/m(3)), toluene (0.14-1.48g/m(3)) and gas-flow rate (0.024-0.072m(3)/h). At comparable loading rates, benzene removal in the mixture was reduced in the range of 6.6-41% in comparison with the individual benzene degradation. Toluene removal in mixture was even more affected as observed from the reductions in REs, ranging from 18.4% to 76%. The results were statistically interpreted by performing an analysis of variance (ANOVA) to elucidate the main and interaction effects. PMID:25827361

  16. Output power characteristics of the neutral xenon long laser

    SciTech Connect

    Linford, G.J. [TRW Space and Electronics Group, Redondo Beach, CA (United States). Space and Technology Div.

    1994-12-31

    Lasers which oscillate within inhomogeneously broadened gain media exhibit spectral hole burning and concomitant reduction in output power compared with equivalent homogeneously-broadened laser gain media. By increasing the cavity length, it may be possible to demonstrate at least a partial transition from an inhomogeneous laser cavity mode spectrum to a homogeneous spectrum. There are a number of high gain laser lines which are inhomogeneously-broadened transitions in electric discharges of neutral xenon. In neutral xenon lasers, as in the cases of many other gas lasers, the inhomogeneous spectral broadening mechanism arises from Doppler shifts, {Delta}{nu}{sub D}, of individual atoms in thermal motion within the electric discharge comprising the laser gain medium. Optical transitions corresponding to these noble gas atoms have natural linewidths, {Delta}{nu}{sub n}{lt}{Delta}{nu}{sub D}. Simulations of the output power characteristics of the xenon laser were carried out as a function of laser cavity parameters, including the cavity length, L. These calculations showed that when the intracavity mode spacing frequency, c/2L{lt}{Delta}{nu}{sub n}, the inhomogeneously broadened xenon mode spectrum converted to a homogeneously broadened oscillation spectrum with an increase in output power. These simulations are compared with experimental results obtained for the long laser oscillation characteristics of the (5d[5/2]{degree}{sub 2}{r_arrow}6p[3/2]{sub 1}) transition corresponding to the strong, high-gain 3.508 {mu} line in xenon.

  17. Separation of gas mixtures by supported complexes. Final report, 1 October 1982-30 September 1984

    SciTech Connect

    Nelson, D.A.; Hallen, R.T.; Lilga, M.A.

    1985-01-01

    This final report covers research performed to identify and demonstrate advantageous procedures for the chemical separation of gases, such as CO, CO/sub 2/, and H/sub 2/, from medium-Btu gas mixtures by use of supported complexes. Three complexes were chosen for rapid gas uptake and selectivity at 25/sup 0/C from among a group of 22 coordination complexes synthesized during this program. The three complexes showed considerable selectivity toward individual gases. For instance, Pd/sub 2/(dpm)/sub 2/Cl/sub 2/ or bis-..mu..-(bisdiphenylphosphinomethane)-dichlorodipalladium (Pd-Pd), rapidly bound carbon monoxide from solution. This complex could be regenerated, with the carbon monoxide reversibly removed, by warming to 40/sup 0/C. The presence of other gases, such as carbon dioxide, oxygen, nitrogen, hydrogen, ethylene, or acetylene, had no effect upon the rapid uptake of carbon monoxide or its removal. Such selectivity was also noted with Ru(CO)/sub 2/(PPh/sub 3/)/sub 3/, biscarbonyltris(triphenylphosphine)ruthenium. Although this complex bound hydrogen, carbon monoxide, and oxygen in solution, the hydrogen was taken up twice as fast as carbon monoxide and seven times faster than oxygen. These gases could be removed from the complex with mild heat or decreased pressure. Crystalline Rh(OH)(CO)(PPh/sub 3/)/sub 2/, hydroxocarbonylbis(triphenylphosphine)rhodium, rapidly bound carbon dioxide; the complex was regenerated at 50/sup 0/C under reduced pressure. The rapid uptake of carbon dioxide by this complex was not changed in the presence of oxygen. In general the three selected crystalline or solvent dissolved complexes performed well in the absence of polymeric support. The stability and favorable kinetics of the three complexes suggest that they could be utilized in a solution system for gas separation (Conceptual Analyses and Preliminary Economics). Further, these complexes appear to be superb candidates as transport agents for facilitated-transport, membrane systems. 69 references, 21 figures.

  18. Drift-velocity and electron-density measurements in electron-beam-irradiated Ar-F2 gas mixtures subjected to an external electric field

    Microsoft Academic Search

    Z. Rozenberg; M. Lando; M. Rokni

    1988-01-01

    Measurements of drift velocity and electron density in electron-beam-irradiated Ar-F2 gas mixtures which have been subjected to an externally applied electric field are reported. The electron density was measured by time-resolved infrared interferometry. The drift velocity was derived from discharge-current-density measurements. Experiments were performed for gas mixtures with various fluorine concentrations between 0.025% and 2% and total mixture pressures between

  19. Improving Spectroscopic Performance of a Coplanar-Anode High-Pressure Xenon Gamma-Ray Spectrometer

    SciTech Connect

    Kiff, Scott D.; He, Zhong; Tepper, Gary C.

    2007-08-04

    High-pressure xenon (HPXe) gas is a desirable radiation detection medium for homeland security applications because of its good inherent room-temperature energy resolution, potential for large, efficient devices, and stability over a broad temperature range. Past work in HPXe has produced large-diameter gridded ionization chambers with energy resolution at 662 keV between 3.5 and 4% FWHM. However, one major limitation of these detectors is resolution degradation due to Frisch grid microphonics. A coplanar-anode HPXe detector has been developed as an alternative to gridded chambers. An investigation of this detector’s energy resolution is reported in this submission. A simulation package is used to investigate the contributions of important physical processes to the measured photopeak broadening. Experimental data is presented for pure Xe and Xe+0.2%H2 mixtures, including an analysis of interaction location effects on the energy spectrum.

  20. Xenon and krypton isotopes in extraterrestrial regolith soils and in the solar wind

    Microsoft Academic Search

    R. O. Pepin; R. H. Becker; P. E. Rider

    1995-01-01

    Isotopic distributions of pure solar-wind xenon and krypton are derived from an extensive data base of xenon and krypton compositions evolved from lunar and meteoritic regolith samples by acid-etching or combustion-pyrolysis experiments in several different laboratories. Regolith Xe and Kr are nonuniform mixtures of primary solar-wind components with others arising in situ from cosmic-ray spallation, neutron-capture in iodine and bromine,

  1. Electron excitation coefficients in xenon

    Microsoft Academic Search

    A. Strinic; G. Malovic; J. Bozin; Z. Lj. Petrovic

    1999-01-01

    We have performed measurements of excitation coefficients for electron swarms in xenon for the range of E\\/N from 90 Td to 10 kTd. The measurements were performed for 2p_1, 2p_2, 2p_3, 2p_4, 2p_5, 2p_6, 3p_5, 3p_6, 3p_7, 3p_8, and 3p_10 levels of neutral xenon and for 6p^4D^0 and 6p^4P^0 of xenon ion. The results were obtained in self-sustained low current

  2. Similarity solutions of a strong shock wave propagation in a mixture of a gas and dusty particles

    NASA Technical Reports Server (NTRS)

    Pai, S. I.; Menon, S.; Fan, Z. Q.

    1980-01-01

    The similarity solutions of a strong shock wave propagation in a mixture of a gas and small solid particles have been investigated. Similarity solution exists only when the shock is very strong and the surrounding medium is of a constant density and at rest and with negligible counterpressure. The non-dimensional fundamental equations are derived and studied. The results depend on three non-dimensional parameters; i.e. (1) the ratio of the specific heats of the gas, (2) the mass concentration of the solid particles in the mixture and (3) the ratio of the density of the solid to that of initial density of the gas. Numerical solutions for various values of these parameters are presented and discussed. The speeds of the shock wave front and its location with various energy releases are given.

  3. Inert Gas Dilution Effect on the Flammability Limits of Hydrocarbon Mixtures

    E-print Network

    Zhao, Fuman

    2012-02-14

    .3 Numerical data analysis?????...????..??????.... 81 5.3.1 Hydrocarbon mixture LFL?????...???????..81 5.3.2 Hydrocarbon mixture UFL?????...???????..95 5.4 Fuel mixture MIC ???????????...?..?????..111 ix CHAPTER... Page 5.7 MICs of ethylene and propylene mixtures from experimental measurement and calculation using Eq. (5-10)???????????...113 6.1 Pure fuel (CaHb) combustion productions at LFL with additional nitrogen???????????????????????????119 6...

  4. Dynamics of Xenon Plasma Streams Generated by Magnetoplasma Compressor

    SciTech Connect

    Garkusha, I. E.; Chebotarev, V. V.; Ladygina, M. S.; Marchenko, A. K.; Petrov, Yu. V.; Solyakov, D. G.; Tereshin, V. I.; Trubchaninov, S. A.; Byrka, O. V. [Institute of Plasma Physics, NSC KIPT, 61108, Kharkov (Ukraine); Hassanein, A. [Argonne National Laboratory (United States)

    2008-03-19

    The paper presents the investigations of parameters of xenon plasma streams generated by magnetoplasma compressor (MPC) of compact geometry with conical-shaped electrodes and pulsed gas supply. Discharge characteristics and dynamics of the plasma streams, generated by MPC in different operation modes are analyzed. First results of Xe plasma radiation measurements in EUV wave range, obtained with AXUV diodes are presented.

  5. Gas mixtures approach to improve turkey meat shelf life under modified atmosphere packaging: the effect of carbon monoxide.

    PubMed

    Fraqueza, M J; Barreto, A S

    2011-09-01

    Gas mixtures with CO have been applied to beef and pork meat, but no data have been reported regarding their application to poultry meat. The aim of this study was to evaluate the effect of an anaerobic gas mixture with CO on the growth of spoilage flora, color, and lipid oxidation stability of turkey meat under modified atmosphere packaging (MAP) stored at 0°C. Sliced meat samples were individually packaged under aerobiosis (aerobic packaging) and in 4 different modified atmospheres containing different gas mixtures: MAP 1, 50% N(2) and 50% CO(2); MAP 2, 0.5% CO, 50% CO(2), and 49.5% N(2); MAP 3, 0.5% CO, 80% CO(2), and 19.5% N(2); and MAP 4, 100% N(2). All the samples were stored at 0 ± 1°C in the dark for 12 to 25 d. Meat samples packaged in aerobic packaging were analyzed for their microbial and physicochemical characteristics on d 0, 5, and 12 of storage, which was extended to 19 and 25 d when samples were under MAP. For meat packaged with MAP 3, the total mesophilic and psychrotrophic counts were significantly lower (P < 0.001) than those observed in condition MAP 1. The introduction of CO, added to a higher concentration of CO(2), inhibited microbial flora in general, with particular action on Brochothrix thermosphacta. In terms of microbial quality, the shelf life of turkey meat under the MAP study conditions was longer than that of meat in aerobic packaging (5 d): 12 d for mixture MAP 4, 19 d for MAP 1 and MAP 2, and 25 d for MAP 3. Only MAP 4 without CO(2) or CO prevented lipid oxidation of the meat. The presence of CO in anoxic gas mixtures with CO(2) for turkey meat under MAP was useful, giving the bright pink color preferred by consumers without leading to the appearance of undercooked meat. PMID:21844276

  6. Radiation-induced reactions of CO?H 2 gas mixtures over various solid catalysts

    NASA Astrophysics Data System (ADS)

    Nagai, S.; Arai, H.; Hatada, M.

    Studies have been carried out of radiation-induced reactions of CO?H 2 gas mixtures in the presence of various solid catalysts in order to find possibilities of synthesizing organic raw materials from CO?H 2 by radiation for the future. The solid catalysts studied include Fischer-Tropsch catalyst (Fe?Cu supported by diatomaceous earth), titania(TiO 2), and silica gel. Analysis of the reaction products over Fischer-Tropsch catalyst or semiconductors such as TiO 2 and ZnO?Cr 2O 3 reveals that these solid catalysts do not sensitize the radiation chemical reaction of CO?H 2 but show the secondary effects on the reaction so as to induce the hydrogenation of olefins produced by the catalytic reaction and of aldehydes produced in gas phase by radiation. On the other hand, silica gel and other insulators such as alumina have been found to exhibit high catalytic activity in the formation of hydrocarbons from CO?H 2 under electron beam irradiation at 300°C. It has been shown experimentally that secondary reactions between H 2 and carbonaceous solid produced from CO make a substantial contribution to the formation of hydrocarbons from CO?H 2 over silica gel. In an attempt to find the role of silica gel in the reaction to produce hydrocarbons, radiation-induced reactions have been studied of H 2 with the carbonaceous solid that had been produced by irradiation of CO in the absence of solid catalyst, over TiO 2, or over silica gel. The results indicate that silica gel not only enhances the yields of CO 2 and carbonaceous solid from CO but also promotes hydrogenation reactions of the carbonaceous solid under electron beam irradiation.

  7. Electron loss and transfer for 20--110-keV iodine--rare-gas collisions

    SciTech Connect

    Hird, B.; Orakzai, M.W.; Rahman, F.

    1989-05-15

    Atomic cross sections have been measured for the loss and transfer of an electron during a collision between a neutral iodine atom and a rare-gas atom. The neutral iodine beam, with energy between 20 to 110 keV, was unlikely to contain a significant mixture of metastable-state atoms because it was produced by neutralizing a negative-iodine-ion beam. The sigma/sub 0+/ cross section is largest for the argon and krypton targets, not for xenon, as might have been expected. The sigma/sub 0-/ cross section is very small for the light targets and only becomes appreciable for xenon at the highest energy used.

  8. Solubilized xenon 133 lung scintigraphy

    SciTech Connect

    Oates, E.; Sarno, R.C.

    1988-11-01

    Lung scanning using solubilized xenon 133 can provide important information concerning both pulmonary perfusion and ventilation. This technique proved valuable in establishing the diagnosis of congenital lobar emphysema in a 7-month-old baby.

  9. A photochemical answer to the 'xenon paradox'

    NASA Astrophysics Data System (ADS)

    Hébrard; Marty, B.

    2012-12-01

    Xenon is depleted by one order of magnitude relative to other volatile elements when normalized to the chondritic composition. Furthermore, atmospheric xenon is far more enriched in the heavy isotopes relatively to chondritic and solar compositions (3-4%.amu-1) than atmospheric krypton (< 1%.amu-1). This discrepancy, known as the 'xenon paradox', has led to sophisticated models of atmospheric evolution coupled with mantle geodynamics (Pepin, 1991; Tolstikhin and Marty, 1998) and cometary contributions (Dauphas, 2003; Owen et al., 1992) that could explain terrestrial noble gas patterns under ad hoc conditions during the building stages of the Earth, no more than ~200 Ma following the beginning of solar system formation. Yet, xenon having an isotopic composition intermediate between the atmospheric and the chondritic ones has been recently documented in Archean (?3 Ga-old) sedimentary rocks (Pujol et al., 2011), suggesting that isotopic fractionation of Xe occurred over a much longer period of time than previously thought, during the Hadean and the Archean eons. In that case, assuming a Rayleigh type isotope evolution for atmospheric Xe requires an enrichment fractionation factor of 1.3% in heavy isotopes for Xe remaining in the atmosphere. This is clearly within the range of values observed in laboratory experiments aimed at trapping and fractionating Xe isotopes in solids, which is only effective upon ionization (Marrocchi et al., 2011; Kuga et al., 2012). We report here a possibility for explaining the 'xenon paradox' through interaction of the Hadean/Archean atmosphere with EUV light from the young Sun. By using a new photochemical model, we have found out that atmospheric Xe depletion and enrichment in heavy Xe isotopes could be achieved by EUV photoionization deep enough in the atmosphere to allow the preferential implantation of the heavier Xe isotopes in organic aerosols, the formation of which is itself triggered by UV photochemistry. Most of the ionized Xe would have escaped from the atmosphere into space by hydrodynamic escape (Zahnle, 2011). We have established that this mechanism specifically affected Xe and was particularly effective during the Hadean/Archean times, since the irradiation flux was expected to be orders of magnitude higher than today (Ribas et al., 2010). Dauphas (2003), Icarus 165, 326-339. Kuga et al. (2012), #2347 Goldschmidt 2012 Marrocchi et al. (2011), GCA 75, 6255-6266. Owen et al. (1992), Nature 358, 43-46. Pepin (1991), Icarus 92, 1-79. Pujol et al. (2011), Earth Planet. Sci. Lett. 308, 298-306. Ribas et al. (2010), Astrophys. J. 714, 384-395. Srinivasan, (1976), Earth Planet. Sci. Lett. 31, 129-141. Tolstikhin and Marty (1998), Chem. Geol. 147, 27-52. Zahnle (2011), #2241 Goldschmidt 2011

  10. The Role of the Velocity Distribution in the Dsmc Pressure Boundary Condition for Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Ahmadzadegan, Amir; Wen, John; Renksizbulut, Metin

    2012-12-01

    A prescribed pressure is the most common flow boundary condition used in flow simulations. In the Direct Simulation Monte Carlo (DSMC) method, boundary pressure is controlled by the number flux of the simulating molecules entering the domain. In the conventional DSMC algorithm, this number flux is calculated iteratively using sampled values of velocity and number density by means of an expression derived from the Maxwell distribution function. It is known that this procedure does not work well for low speed flows which are of interest in most micro-flow applications and the statistical scatter of the DSMC results is generally stated to be the main reason. However, the Maxwell distribution used in the pressure boundary treatment is valid for equilibrium conditions, and therefore, current implementations of the DSMC pressure boundary treatment are limited to boundaries with sufficiently small rarefaction effects. This is not the case for some practical problems in which highly rarefied flows through the boundaries lead to considerable nonequilibrium effects. In this study, an expression for the species number flux is derived using the Chapman-Enskog velocity distribution to improve the pressure boundary condition. The resulting algorithm is then used for modeling a micro-channel binary gas mixture flow with prescribed pressure boundary conditions.

  11. Studies of Helium Based Gas Mixtures Using a Small Cell Drift Chamber

    SciTech Connect

    Heise, Jaret; /British Columbia U.

    2006-07-07

    An international collaboration is currently working on the construction and design of an asymmetric B Factory at the Stanford Linear Accelerator Center that will be ready to collect data in 1999. The main physics motivation for such a facility is to test the description and mechanism of CP violation in the Standard Model of particle physics and provide insight into the question of why more matter than antimatter is observed in the universe today. In particular, this experiment will measure CP violation in the decay of B mesons. In the early stages of this effort, the Canadian contingent proposed to build the central tracking chamber for the BaBar detector. Presently, a prototype drift chamber is in operation and studies are being performed to test some of the unique features of drift chamber design dictated by the conditions of the experiment. Using cosmic muons, it is possible to study tracking and pattern recognition in the prototype chamber, and therefore calculate the efficiency and spatial resolution of the prototype chamber cells. These performance features will be used to test whether or not the helium-based gas mixtures proposed for the BaBar drift chamber are a viable alternative to the more traditional argon-based gases.

  12. Dynamic Characteristics of SF6-N2-CO2 Gas Mixtures in DC Discharge Process

    NASA Astrophysics Data System (ADS)

    Zheng, Dianchun; Wang, Jia; Chen, Chuntian; Zhao, Dawei; Zhang, Chunxi; Yang, Jiaxiang

    2014-09-01

    Dynamic characteristics of discharge particles are described within the framework of a two-dimensional photoionization-hydrodynamic numerical model for the discharge process of SF6-N2-CO2 gas mixtures at atmospheric pressure, under a uniform DC applied field. The finite difference—flux corrected transport (FD-FCT) algorithm is used in the numerical implementation for improving the accuracy and efficiency. Then the tempo-spatial distributions of the gap—space electric field and electron velocity are calculated from the microscopic mechanism, and the dynamic behaviors of charged particles are obtained in detail. Meanwhile, the tempo—spatial critical point of the avalanche-to-streamer in this model is discovered, and several microscopic parameters are also investigated. The results showed that the entire gap discharge process can be divided into two phases of avalanche and streamer according to Raether-Meek criterion; the electron density within the discharge channel is lower compared to that of positive and negative ions; space charge effect is a dominant factor for the distortion of spatial electric field, making the discharge channel expand toward both electrodes faster; photoionization provides seed electrons for a secondary electron avalanche, promoting the formation and development speed of the streamer.

  13. Silicon surface damage caused by reactive ion etching in fluorocarbon gas mixtures containing hydrogen

    SciTech Connect

    Norstroem, H. (Ericsson Components AB, S-164 81 Kista-Stockholm (Sweden)); Blom, H. (Institute of Technology, S-751 21 Uppsala (Sweden)); Ostling, M. (Royal Institute of Technology, Department of Solid State Electronics-Electrum, S-164 28 Kista (Sweden)); Nylandsted Larsen, A. (Institute of Physics, University of Aarhus, Dk-8000 Aarhus C, (Denmark)); Keinonen, J. (University of Helsinki, Accelerator Laboratory, Haemeentie 100, SF-00550, Helsinki 55 (Finland)); Berg, S. (Institue of Technology, S-751 21, Uppsala (Sweden))

    1991-01-01

    For selective etching of SiO{sub 2} on silicon, gases or gas mixtures containing hydrogen are often used. Hydrogen from the glow discharge promotes the formation of a thin film polymer layer responsible for the selectivity of the etching process. The reactive ion etch (RIE) process is known to create damage in the silicon substrate. The influence of hydrogen on the damage and deactivation of dopants is investigated in the present work. The distribution of hydrogen in silicon, after different etching and annealing conditions have been studied. The influence of the RIE process on the charge carrier concentration in silicon has been investigated. Various analytical techniques like contact resistivity measurements, four point probe measurements, and Hall measurements have been used to determine the influence of the RIE process on the electrical properties of processed silicon wafers. The hydrogen profile in as-etched and post annealed wafers was determined by the {sup 1}H({sup 15}N,{alpha}{gamma}){sup 12}C nuclear reaction. The depth of the deactivated surface layer is discussed in terms of the impinging hydrogen ion energy, i.e., the possibility of H{sup +} ions to pick up an energy equal to the peak-to-peak voltage of the rf signal.

  14. Transport phenomena and conservation equations in multicomponent chemically-reactive ideal gas mixtures

    SciTech Connect

    Sohrab, S.H. [Northwestern Univ., Evanston, IL (United States)

    1996-12-01

    The symmetric forms of the conservation equations for mass, energy, and momentum in reactive ideal gas mixtures are presented. A modified form of the continuity equation is introduced which accounts for possible diffusion of mass under the gradient of density in simple fluids, similar to the Smoluchowski equation describing the Brownian motion of small particles suspended in a fluid subject to an external force. An intermediate statistical field called cluster-dynamics is postulated and the statistically-stationary nature of the Brownian motions of small suspensions in stationary fluids is attributed to the fact that the suspensions are in equilibrium with molecular-clusters, that themselves possess Brownian motions. The Newton law of viscosity is generalized through the introduction of momentum diffusion velocity V{sub ij} and the rate of stress tensor is defined in terms of the corresponding diffusional flux of momenta. A modified form of the Navier-Stokes equation is presented that includes a source (sink) of momentum caused by heat release (absorption) associated with exothermic (endothermic) chemical reactions. The equivalence between the modified and the original forms of the Navier-Stokes equation is established. The symmetric forms of the conservation equations, in the absence of dissipations, are then used to derive four wave equations which describe the propagation of density, temperature, pressure, and velocity perturbations at the cluster-dynamic scale. The results may provide certain guidelines towards the identification of a scale-invariant statistical theory of turbulence in chemically-reactive hydrodynamic fields. 35 refs.

  15. A Three-Dimensional Optical Lattice of Ytterbium and Lithium Atomic Gas Mixture

    NASA Astrophysics Data System (ADS)

    Hara, Hideaki; Konishi, Hideki; Nakajima, Shuta; Takasu, Yosuke; Takahashi, Yoshiro

    2014-01-01

    We develop an optical lattice system for an ultracold atomic gas mixture of ytterbium (174Yb) and lithium (6Li), which is an ideal system for studying disorder and impurity problems. We load a Bose–Einstein condensate of 174Yb into a three-dimensional optical lattice and observe its interference patterns in time-of-flight (TOF) images. Furthermore, we perform laser spectroscopy of 174Yb in an optical lattice using the ultranarrow optical transition 1S0–3P2 in both cases with and without 6Li. Owing to the weak interspecies interaction, we do not observe clear effects of 6Li in the obtained interference patterns or excitation spectra. However, this is an important first step in the optical control of atomic impurity in ultracold fermions. We also measure the polarizabilities of the 3P2 state of 174Yb atoms in an optical trap with a wavelength of 1070 nm. We reveal that the polarizability can be tuned to be positive, zero, or the same as the ground state, which is useful for certain applications.

  16. Demonstration of Soft X-Ray Lasing with Neonlike Argon and Nickel-like Xenon Ions Using a Laser-Irradiated Gas Puff Target

    Microsoft Academic Search

    H. Fiedorowicz; A. Bartnik; Y. Li; P. Lu; E. Fill

    1996-01-01

    We report the first demonstration of soft x-ray amplification in an elongated plasma column produced by laser irradiation of a gas puff target. The gas puff target is formed by the pulsed injection of gas from a high-pressure solenoid valve through a nozzle in the form of a narrow slit. The plasma column to be used as an x-ray laser

  17. Development of a xenon detector for treaty verification. Final report

    SciTech Connect

    NONE

    1998-07-21

    The project objective was to determine the feasibility of the gas proportional scintillator detector (GPSD) technology to sensitively and selectively detect the decay products of the metastable xenon isotopes as a means of treaty verification for the CTBT. During the course of the project, the investigation involved both computer simulations and laboratory measurements with a GPSD. During the fourth quarter the authors have further investigated the dedicated GPSD response to x-rays and conversion electrons from {sup 109}Cd and {sup 57}Co radioactive sources, comparing simulated and experimental results. The response of a customized high pressure GPSC was also simulated to the higher energy conversion electrons from xenon radioisotopes. An alternative hybrid detector system is proposed showing excellent prospects for xenon radioisotope detection.

  18. Liquid Hole Multipliers: bubble-assisted electroluminescence in liquid xenon

    E-print Network

    L. Arazi; E. Erdal; A. E. C. Coimbra; M. L. Rappaport; D. Vartsky; V. Chepel; A. Breskin

    2015-05-13

    In this work we discuss the mechanism behind the large electroluminescence signals observed at relatively low electric fields in the holes of a Thick Gas Electron Multiplier (THGEM) electrode immersed in liquid xenon. We present strong evidence that the scintillation light is generated in xenon bubbles trapped below the THGEM holes. The process is shown to be remarkably stable over months of operation, providing - under specific thermodynamic conditions - energy resolution similar to that of present dual-phase liquid xenon experiments. The observed mechanism may serve as the basis for the development of Liquid Hole Multipliers (LHMs), capable of producing local charge-induced electroluminescence signals in large-volume single-phase noble-liquid detectors for dark matter and neutrino physics experiments.

  19. Liquid Hole Multipliers: bubble-assisted electroluminescence in liquid xenon

    E-print Network

    Arazi, L; Coimbra, A E C; Rappaport, M L; Vartsky, D; Chepel, V; Breskin, A

    2015-01-01

    In this work we discuss the mechanism behind the large electroluminescence signals observed at relatively low electric fields in the holes of a Thick Gas Electron Multiplier (THGEM) electrode immersed in liquid xenon. We present strong evidence that the scintillation light is generated in xenon bubbles trapped below the THGEM holes. The process is shown to be remarkably stable over months of operation, providing - under specific thermodynamic conditions - energy resolution similar to that of present dual-phase liquid xenon experiments. The observed mechanism may serve as the basis for the development of Liquid Hole Multipliers (LHMs), capable of producing local charge-induced electroluminescence signals in large-volume single-phase noble-liquid detectors for dark matter and neutrino physics experiments.

  20. Single Ion Trapping for the Enriched Xenon Observatory

    SciTech Connect

    Waldman, Samuel J.; /Stanford U., Phys. Dept. /SLAC; ,

    2006-03-28

    In the last decade, a variety of neutrino oscillation experiments have established that there is a mass difference between neutrino flavors, without determining the absolute neutrino mass scale. The Enriched Xenon Observatory for neutrinoless double beta decay (EXO) will search for the rare decays of xenon to determine the absolute value of the neutrino mass. The experiment uses a novel technique to minimize backgrounds, identifying the decay daughter product in real time using single ion spectroscopy. Here, we describe single ion trapping and spectroscopy compatible with the EXO detector. We extend the technique of single ion trapping in ultrahigh vacuum to trapping in xenon gas. With this technique, EXO will achieve a neutrino mass sensitivity of {approx_equal} .010 eV.

  1. 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. PMID:23368058

  2. Modeling high-pressure adsorption of gas mixtures on activated carbon and coal using a simplified local-density model.

    PubMed

    Fitzgerald, James E; Robinson, Robert L; Gasem, Khaled A M

    2006-11-01

    The simplified local-density (SLD) theory was investigated regarding its ability to provide accurate representations and predictions of high-pressure supercritical adsorption isotherms encountered in coalbed methane (CBM) recovery and CO2 sequestration. Attention was focused on the ability of the SLD theory to predict mixed-gas adsorption solely on the basis of information from pure gas isotherms using a modified Peng-Robinson (PR) equation of state (EOS). An extensive set of high-pressure adsorption measurements was used in this evaluation. These measurements included pure and binary mixture adsorption measurements for several gas compositions up to 14 MPa for Calgon F-400 activated carbon and three water-moistened coals. Also included were ternary measurements for the activated carbon and one coal. For the adsorption of methane, nitrogen, and CO2 on dry activated carbon, the SLD-PR can predict the component mixture adsorption within about 2.2 times the experimental uncertainty on average solely on the basis of pure-component adsorption isotherms. For the adsorption of methane, nitrogen, and CO2 on two of the three wet coals, the SLD-PR model can predict the component adsorption within the experimental uncertainties on average for all feed fractions (nominally molar compositions of 20/80, 40/60, 60/40, and 80/20) of the three binary gas mixture combinations, although predictions for some specific feed fractions are outside of their experimental uncertainties. PMID:17073487

  3. Modeling high-pressure adsorption of gas mixtures on activated carbon and coal using a simplified local-density model

    SciTech Connect

    Fitzgerald, J.E.; Robinson, R.L.; Gasem, K.A.M. [Oklahoma State University, Stillwater, OK (United States). School of Chemical Engineering

    2006-11-07

    The simplified local-density (SLD) theory was investigated regarding its ability to provide accurate representations and predictions of high-pressure supercritical adsorption isotherms encountered in coalbed methane (CBM) recovery and CO{sub 2} sequestration. Attention was focused on the ability of the SLD theory to predict mixed-gas adsorption solely on the basis of information from pure gas isotherms using a modified Peng-Robinson (PR) equation of state (EOS). An extensive set of high-pressure adsorption measurements was used in this evaluation. These measurements included pure and binary mixture adsorption measurements for several gas compositions up to 14 MPa for Calgon F-400 activated carbon and three water-moistened coals. Also included were ternary measurements for the activated carbon and one coal. For the adsorption of methane, nitrogen, and CO{sub 2} on dry activated carbon, the SLD-PR can predict the component mixture adsorption within about 2.2 times the experimental uncertainty on average solely on the basis of pure-component adsorption isotherms. For the adsorption of methane, nitrogen, and CO{sub 2} on two of the three wet coals, the SLD-PR model can predict the component adsorption within the experimental uncertainties on average for all feed fractions (nominally molar compositions of 20/80, 40/60, 60/40, and 80/20) of the three binary gas mixture combinations, although predictions for some specific feed fractions are outside of their experimental uncertainties.

  4. Working process study of a novel scroll type multiphase pump for the transportation of gas-liquid mixtures

    NASA Astrophysics Data System (ADS)

    Wang, J.; Zha, H. B.; Zhang, X. H.; Zhang, D. H.

    2012-11-01

    A novel scroll type multiphase pump was proposed to transport gas-liquid two-phase mixture. There is a pressure unloading gap from compression chambers to the discharge port by constructing scroll wrap profile with variational meshing clearance in this scroll multiphase pump. In the working process when the volume of working chamber decreases, the pressure of gas-liquid mixtures increases gradually, at the same time small amounts of gas-liquid mixture are pushed to the discharge port from compression chambers through the pressure unloading gap. Therefore, this multiphase pump has an advantage of unloading pressure method automatically, and the frequently problem of liquid impacting in volume multiphase pump is solved. The safety and reliability of volumetric multiphase pump are improved, and the scope of multiphase pump of the gas-liquid ratio is expanded. The working process and the performance characteristics of scroll multiphase pump were analyzed too, and the generation method of scroll wrap profile with variational meshing clearance was investigated. The equations of the profile were obtained, and the changing principle of the working volume and the meshing clearance were analyzed. The geometric theory of scroll multiphase pump was formed. All of that lay the theoretical foundation for engineering design of this novel scroll.

  5. Materials selection guidelines for membranes that remove CO 2 from gas mixtures

    NASA Astrophysics Data System (ADS)

    Lin, Haiqing; Freeman, Benny D.

    2005-04-01

    Membrane technology has been investigated for removing CO 2 from mixtures with light gases such as CH 4, N 2 and H 2, and optimal membranes with high CO 2 permeability and high CO 2/light gas selectivity are of great interest. This overview describes the material science approaches to achieve high CO 2 solubility and CO 2/light gas solubility selectivity by introducing polar groups in polymers. CO 2 solubility and CO 2/N 2 solubility selectivity in both liquid solvents and solid polymers containing a variety of polar groups are discussed. Optimum materials appear to have a solubility parameter of about 21.8 MPa 0.5 to achieve both high solubility and high solubility selectivity. However, the introduction of polar groups can decrease CO 2 diffusion coefficients and can make a material more size-selective, which is detrimental to, for example, CO 2/H 2 separation properties. So far, ether oxygens in ethylene oxide (EO) units appear to provide a good balance of CO 2 separation and permeation properties. One drawback of using pure poly(ethylene oxide) (PEO) is its strong tendency to crystallize. This report reviews strategies for incorporating high concentrations of EO units into polymers while suppressing crystallization. A simple model, based on free volume theory, is used to correlate a wide range of CO 2 permeability coefficients in PEO containing materials, and the results are satisfactory, particularly given the simplicity of the model. Crosslinked poly(ethylene glycol) acrylate (XLPEO) containing branches with methoxy end groups exhibit the highest CO 2 permeability (i.e. 570 Barrers) and highest CO 2/H 2 selectivity (i.e. 12) at 35 °C and infinite dilution among all PEO containing materials reported to date. Because such materials do not crystallize at typically accessible temperatures, CO 2/H 2 selectivity can be further improved by decreasing temperature. For example, at an upstream pressure of 4.4 atm, CO 2/H 2 pure gas selectivity reaches a value of 40 at -20 °C while maintaining a CO 2 permeability of 52 Barrers.

  6. Sparkover Characteristics in CF3I Gas and CF3I/N2 Gas Mixture under Non-uniform Field Gaps

    NASA Astrophysics Data System (ADS)

    Takeda, Toshinobu; Matsuoka, Shigeyasu; Kumada, Akiko; Hidaka, Kunihiko

    A steep-front square pulse voltage generator, which has a rise time of 16ns, a dumping factor less than 2.5% after 10?s duration and a peak value of 200kV, is successfully used to survey the V-t characteristics in nanosecond range. The V-t characteristics of CF3I, SF6, CF3I/N2 and SF6/N2 gas mixtures under non-uniform field gaps by using the steep-front square pulse voltage. When the field utilization factor are measured less than 0.38, the sparkover voltage of CF3I is lower than that of SF6. On the contrary, when the field utilization factor is more than 0.38, the sparkover voltage of CF3I is higher than that of SF6. The corona inception voltage calculated by using Schumann's criteria and compared with measured one. The V-t characteristics for a uniform field gap in CF3I/N2 gas mixture containing N2 gas of 40% are equivalent to those in pure SF6 gas. The synergism for appears when CF3I gas is mixed with N2 gas.

  7. Coherent soft X-ray high-order harmonics using tight-focusing laser pulses in the gas mixture.

    PubMed

    Lu, Faming; Xia, Yuanqin; Zhang, Sheng; Chen, Deying; Zhao, Yang; Liu, Bin

    2014-01-01

    We experimentally study the harmonics from a Xe-He gas mixture using tight-focusing femtosecond laser pulses. The spectrum in the mixed gases exhibits an extended cutoff region from the harmonic H21 to H27. The potential explanation is that the harmonics photons from Xe contribute the electrons of He atoms to transmit into the excited-state. Therefore, the harmonics are emitted from He atoms easily. Furthermore, we show that there are the suppressed harmonics H15 and H17 in the mixed gases. The underlying mechanism is the destructive interference between harmonics generated from different atoms. Our results indicate that HHG from Xe-He gas mixture is an efficient method of obtaining the coherent soft X-ray source. PMID:24463389

  8. Adsorption behavior of ternary mixtures of noble gases inside single-walled carbon nanotube bundles

    NASA Astrophysics Data System (ADS)

    Foroutan, Masumeh; Nasrabadi, Amir Taghavi

    2010-09-01

    In order to study the gas-storage and gas-filtering capability of carbon nanotube (CNT) bundles simultaneously, we considered the adsorption behavior of a ternary mixture of noble gases, including Argon (Ar), Krypton (Kr), and Xenon (Xe), i.e., Ar-Kr-Xe mixture, on (10, 10) single-walled carbon nanotube (SWCNT) bundles. Molecular dynamics (MD) simulations at different temperatures of (75, 100, 150, 200, 250, and 300) K were performed, and adsorption energies, self-diffusion coefficients, activation energies, and radial distribution functions (RDFs) were computed to analyze the thermodynamics, transport and structural properties of the adsorption systems. It is observed that the SWCNT bundles have larger contents of heavier noble gases compared to the lighter ones. This interesting behavior of SWCNT bundles makes them proper candidates for gas-storage and gas molecular-sieving processes.

  9. Numerical Prediction of Radiation Measurements Taken in the X2 Facility for Mars and Titan Gas Mixtures

    NASA Technical Reports Server (NTRS)

    Palmer, Grant; Prabhu, Dinesh; Brandis, Aaron; McIntyre, Timothy J.

    2011-01-01

    Thermochemical relaxation behind a normal shock in Mars and Titan gas mixtures is simulated using a CFD solver, DPLR, for a hemisphere of 1 m radius; the thermochemical relaxation along the stagnation streamline is considered equivalent to the flow behind a normal shock. Flow simulations are performed for a Titan gas mixture (98% N2, 2% CH4 by volume) for shock speeds of 5.7 and 7.6 km/s and pressures ranging from 20 to 1000 Pa, and a Mars gas mixture (96% CO2, and 4% N2 by volume) for a shock speed of 8.6 km/s and freestream pressure of 13 Pa. For each case, the temperatures and number densities of chemical species obtained from the CFD flow predictions are used as an input to a line-by-line radiation code, NEQAIR. The NEQAIR code is then used to compute the spatial distribution of volumetric radiance starting from the shock front to the point where thermochemical equilibrium is nominally established. Computations of volumetric spectral radiance assume Boltzmann distributions over radiatively linked electronic states of atoms and molecules. The results of these simulations are compared against experimental data acquired in the X2 facility at the University of Queensland, Australia. The experimental measurements were taken over a spectral range of 310-450 nm where the dominant contributor to radiation is the CN violet band system. In almost all cases, the present approach of computing the spatial variation of post-shock volumetric radiance by applying NEQAIR along a stagnation line computed using a high-fidelity flow solver with good spatial resolution of the relaxation zone is shown to replicate trends in measured relaxation of radiance for both Mars and Titan gas mixtures.

  10. Mechanism of Scintillation of Helium, Helium-Argon, and Helium-Neon Gas Mixtures Excited by Alpha Particles

    Microsoft Academic Search

    Shinzou Kubota; Tan Takahashi; Tadayoshi Doke

    1968-01-01

    An experimental investigation of the mechanism of scintillation of helium, helium-argon, and helium-neon mixtures excited by alpha particles has been performed. No detectable decrease in light yield was observed at pressures less than 3 atm when the applied electric field was increased in steps to Ep~1.0 V\\/cm Torr, where E is the electric field and p is the gas pressure.

  11. Gasification of coal-derived chars in synthesis gas mixtures under intraparticle mass-transfer-controlled conditions

    Microsoft Academic Search

    A. Bliek; J. C. Lont; Swaaij van W. P. M

    1986-01-01

    A model has been formulated to describe the quasi-steady-state gasification of coal-derived chars in gas mixtures where both the reactants carbon dioxide and steam, and the gasification products carbon monoxide and hydrogen are present. As such, these conditions reflect the situation found in most practical gasification systems.\\u000a\\u000aThe model presented is applied under conditions where intraparticle mass transfer is rate-controlling.

  12. Kinetics and mechanism of the desulfurization of liquid blast furnace slags by Ar-H 2 O gas mixtures

    Microsoft Academic Search

    B. Agrawal; G. J. Yurek; J. F. Elliott

    1983-01-01

    The rate of evolution of sulfur-bearing gases from liquid silicate slags at 1400 ‡C when exposed to Ar-H2O gas mixtures has been studied. The rate was first order with respect both to the concentration of sulfur ions adsorbed on\\u000a the surface of the slag and to the partial pressure of water vapor when PH\\u000a 2O was greater than 0.15 atm.

  13. Dry etching of CdTe/GaAs epilayers using CH{sub 4}H{sub 2} gas mixtures

    SciTech Connect

    Neswal, M.; Gresslehner, K.H.; Lischka, K. [Johannes Kepler Universitaet Linz (Austria)] [and others] [Johannes Kepler Universitaet Linz (Austria); and others

    1993-05-01

    A CH{sub 4}/H{sub 2} gas mixture has been used for the dry etching of (100) and (111) oriented CdTe epilayers in a barrel reactor. The effects of various process parameters on etch rate and surface morphology were studied with special attention paid to the gas composition and the total chamber pressure as well as the crystallographic orientation of the sample. Clear evidence is found for both isotropic and preferential etching along crystalolographic planes depending on the set of etch parameters used. 14 refs., 7 figs.

  14. Pulsed-field-gradient measurements of time-dependent gas diffusion.

    PubMed

    Mair, R W; Cory, D G; Peled, S; Tseng, C H; Patz, S; Walsworth, R L

    1998-12-01

    Pulsed-field-gradient NMR techniques are demonstrated for measurements of time-dependent gas diffusion. The standard PGSE technique and variants, applied to a free gas mixture of thermally polarized xenon and O2, are found to provide a reproducible measure of the xenon diffusion coefficient (5.71 x 10(-6) m2 s-1 for 1 atm of pure xenon), in excellent agreement with previous, non-NMR measurements. The utility of pulsed-field-gradient NMR techniques is demonstrated by the first measurement of time-dependent (i.e., restricted) gas diffusion inside a porous medium (a random pack of glass beads), with results that agree well with theory. Two modified NMR pulse sequences derived from the PGSE technique (named the Pulsed Gradient Echo, or PGE, and the Pulsed Gradient Multiple Spin Echo, or PGMSE) are also applied to measurements of time dependent diffusion of laser polarized xenon gas, with results in good agreement with previous measurements on thermally polarized gas. The PGMSE technique is found to be superior to the PGE method, and to standard PGSE techniques and variants, for efficiently measuring laser polarized noble gas diffusion over a wide range of diffusion times. PMID:9878475

  15. Single-Well-Gas-Sparging Tests for Assessing the Feasibility of In-situ Aerobic Treatment of CAH Mixtures

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Istok, J.; Semprini, L.

    2002-12-01

    Single-well-gas-sparge tests were performed to assess the feasibility of in-situ aerobic cometabolism of chlorinated aliphatic hydrocarbons (CAHs), such as trichloroethylene (TCE) and cis-1,2-dichloroethylene (c-DCE), using propane and methane as growth substrates. The tests were performed in the saturate zone at the McClellan Air Force Base, CA. The effectiveness of gas sparging to stimulate indigenous propane-utilizers or methane-utilizers was evaluated in standard monitoring wells. Transport characteristics of dissolved solutes [sulfur hexafluoride (SF6 or bromide (tracer), propane or methane (growth substrate), ethylene, propylene (nontoxic surrogates to probe for CAH transformation activity), and dissolved oxygen], were evaluated by push-pull transport tests. Mass balance showed about 90% of the injected bromide and about 80% of the injected SF6 were recovered, and the recoveries of other solutes were comparable with bromide and SF6. The transport tests demonstrated that bromide and SF6 could be used as conservative tracers for biological activity tests and that little loss of the dissolved gaseous substrates prior to biostimulation occurred. The dissolved gases were also conservatively transported indicating negligible trapped gas was present in the aquifer prior to sparging. A series of gas-sparging biostimulation tests were performed by sparging propane-(or methane)-oxygen-argon-SF6 gas mixture at specific depth intervals using a "straddle" packer. Temporal groundwater samples were obtained from the injection well under natural gradient "drift" conditions. Biostimulation was demonstrated with repeated gas sparging tests where the time to deplete methane and propane concentrations decreased compared to SF6. Gas sparging activity tests were performed using the same procedures as the gas-sparging biostimulation tests, except that ethylene and propylene were included in the sparging gas mixtures. Propane (or methane) utilization, DO consumption, and ethylene and propylene cometabolism were well demonstrated. The stimulated propane- and methane-utilizers cometabolized ethylene and propylene to produce ethylene oxide and propylene oxide as cometabolic by-products. The results confirmed the biostimulation of indigenous microorganisms with cometabolism ability. When acetylene was included in the sparge gas mixture, propane and methane utilization and ethylene and propylene transformation were effectively blocked, indicating monooxygenase enzymes were involved

  16. Radioactive Plume from the Three Mile Island Accident: Xenon133 in Air at a Distance of 375 Kilometers

    Microsoft Academic Search

    Martin Wahlen; Charles O. Kunz; John M. Matuszek; William E. Mahoney; Roger C. Thompson

    1980-01-01

    The transit of an air mass containing radioactive gas released from the Three Mile Island reactor was recorded in Albany, New York, by measuring xenon-133. These measurements provide an evaluation of Three Mile Island effluents to distances greater than 100 kilometers. Two independent techniques identified xenon-133 in ambient air at concentrations as high as 3900 picocuries per cubic meter. The

  17. Temporal pulse compression in a xenon-filled Kagome-type hollow-core photonic crystal fiber

    E-print Network

    Keller, Ursula

    Temporal pulse compression in a xenon-filled Kagome-type hollow-core photonic crystal fiber at high: In this study we demonstrate the suitability of Hollow-Core Photonic Crystal Fibers (HC-PCF) for multiwatt disk laser in a xenon gas filled Kagome-type HC-PCF and compressed these pulses to below 250 fs

  18. Reflectance measurement of the VUV spectrum of solid xenon and its temperature dependence up to the triple point

    E-print Network

    Boyer, Edmond

    L-339 Reflectance measurement of the VUV spectrum of solid xenon and its temperature dependence up disparition vers 135 K. Abstract. 2014 Accurate solid xenon reflectance measurements in the energy range 6. Introduction. - Since Baldini's paper [ 1 ], exten- sive studies on solid rare gas excitonic spectra near

  19. Analytical Method for Measuring Total Protium and Total Deuterium in a Gas Mixture Containing H2, D2, and HD Via Gas Chromatography

    SciTech Connect

    SESSIONS, HENRY

    2004-03-24

    A new analytical technique has been developed that measures both total protium (H) and deuterium (D) in a gas mixture containing H2, D2, and HD. This new analytical technique uses a micro gas chromatograph (GC) with two molecular sieve columns. One column uses D2 as the carrier gas and the other uses H2 as the carrier gas. Laboratory tests have shown that when used in this configuration the GC can measure both total protium and total deuterium, each with a sensitivity of less than 20 ppm. This new analytical technique was developed as a result of a request to provide instrumentation to measure the protium and deuterium concentrations at several process points during initial testing of the new hydrogen tritium thermal cycling absorption process columns.

  20. ANALYTICAL METHOD FOR MEASURING TOTAL PROTIUM AND TOTAL DEUTERIUM IN A GAS MIXTURE CONTAINING H2, D2,AND HD VIA GAS CHAROMATOGRAPHY

    SciTech Connect

    Sessions, H

    2007-08-07

    The most common analytical method of identifying and quantifying non-radioactive isotopic species of hydrogen is mass spectrometry. A low mass, high resolution mass spectrometer with adequate sensitivity and stability to identify and quantify hydrogen isotopes in the low ppm range is an expensive, complex instrument. A new analytical technique has been developed that measures both total protium (H) and total deuterium (D) in a gas mixture containing H{sub 2}, D{sub 2}, and HD using an inexpensive micro gas chromatograph (GC) with two molecular sieve columns. One column uses D{sub 2} as the carrier gas and the other uses H{sub 2} as the carrier gas. Laboratory tests have shown that when used in this configuration the GC can measure both total protium and total deuterium each with a detection and quantification limit of less than 20 ppm.

  1. Study of the formation and decay of KrXe* excimers at room temperature following selective excitation of the xenon 6s states

    Microsoft Academic Search

    G. Ledru; F. Marchal; N. Merbahi; J. P. Gardou; N. Sewraj

    2007-01-01

    The VUV emissions of gaseous mixtures of krypton and xenon were investigated at room temperature. For this purpose, a pulsed, brief, selective multiphotonic excitation of the two lowest atomic states of the 5p56s configuration of xenon was achieved. A spectroscopic and kinetic study was performed, for the first time, by comparing the radiation characteristics consecutive to initially populating either the

  2. Cryptophane-xenon complexes in organic solvents observed through NMR spectroscopy.

    PubMed

    Huber, Gaspard; Beguin, Laetitia; Desvaux, Hervé; Brotin, Thierry; Fogarty, Heather A; Dutasta, Jean-Pierre; Berthault, Patrick

    2008-11-13

    The interaction of xenon with cryptophane derivatives is analyzed by NMR by using either thermal or hyperpolarized noble gas. Twelve hosts differing by their stereochemistry, cavity size, and the nature and the number of the substituents on the aromatic rings have been included in the study, in the aim of extracting some clues for the optimization of (129)Xe-NMR based biosensors derived from these cage molecules. Four important properties have been examined: xenon-host binding constant, in-out exchange rate of the noble gas, chemical shift, and relaxation of caged xenon. This work aims at understanding the main characteristics of the host-guest interaction in order to choose the best candidate for the biosensing approach. Moreover, rationalizing xenon chemical shift as a function of structural parameters would also help for setting up multiplexing applications. Xenon exhibits the highest affinity for the smallest cryptophane, namely cryptophane-111, and a long relaxation time inside it, convenient for conservation of its hyperpolarization. However, very slow in-out xenon exchange could represent a limitation for its future applicability for the biosensing approach, because the replenishment of the cage in laser-polarized xenon, enabling a further gain in sensitivity, cannot be fully exploited. PMID:18925727

  3. The novel use of gas chromatography-ion mobility-time of flight mass spectrometry with secondary electrospray ionization for complex mixture analysis

    Microsoft Academic Search

    Christina L. Crawford; Stephan Graf; Marc Gonin; Katrin Fuhrer; Xing Zhang; Herbert H. Hill Jr

    2011-01-01

    Increasing the dimensionality of an analysis enables more detailed and comprehensive investigations of complex mixtures. One\\u000a dimensional separation techniques like gas chromatography (GC) and ion mobility spectrometry (IMS) provide limited chemical\\u000a information about complex mixtures. The combination of GC, ion mobility spectrometry, and time-of-flight mass spectrometry\\u000a (GC-IM-TOFMS) provides three-dimensional separation of complex mixtures. In this work, a hybrid GC-IM-TOFMS with

  4. Reduced xenon diffusion for quantitative lung study--the role of SF(6)

    NASA Technical Reports Server (NTRS)

    Mair, R. W.; Hoffmann, D.; Sheth, S. A.; Wong, G. P.; Butler, J. P.; Patz, S.; Topulos, G. P.; Walsworth, R. L.

    2000-01-01

    The large diffusion coefficients of gases result in significant spin motion during the application of gradient pulses that typically last a few milliseconds in most NMR experiments. In restricted environments, such as the lung, this rapid gas diffusion can lead to violations of the narrow pulse approximation, a basic assumption of the standard Stejskal-Tanner NMR method of diffusion measurement. We therefore investigated the effect of a common, biologically inert buffer gas, sulfur hexafluoride (SF(6)), on (129)Xe NMR and diffusion. We found that the contribution of SF(6) to (129)Xe T(1) relaxation in a 1:1 xenon/oxygen mixture is negligible up to 2 bar of SF(6) at standard temperature. We also measured the contribution of SF(6) gas to (129)Xe T(2) relaxation, and found it to scale inversely with pressure, with this contribution approximately equal to 1 s for 1 bar SF(6) pressure and standard temperature. Finally, we found the coefficient of (129)Xe diffusion through SF(6) to be approximately 4.6 x 10(-6) m(2)s(-1) for 1 bar pressure of SF(6) and standard temperature, which is only 1.2 times smaller than the (129)Xe self diffusion coefficient for 1 bar (129)Xe pressure and standard temperature. From these measurements we conclude that SF(6) will not sufficiently reduce (129)Xe diffusion to allow accurate surface-area/volume ratio measurements in human alveoli using time-dependent gas diffusion NMR.

  5. Gas emissions and engine behavior when gasoline-alcohol mixtures are used.

    PubMed

    Arapatsakos, C I; Karkanis, A N; Sparis, P D

    2003-09-01

    This paper deals with the use of gasoline-methanol and gasoline-ethanol mixtures in a small four-stroke engine of internal combustion that is used for the movement of a small alternative generator. It was observed that CO and HC emissions decrease compared to gasoline when the percentage of methanol, ethanol in the fuel was increased, under different load conditions (without load conditions and under full electrical load conditions). The use of gasoline-methanol mixtures showed a higher decrease of emissions. When the mixtures of gasoline-70%methanol and gasoline-90%ethanol and 100%ethanol for which the engine malfunctioned, the rpm of the engine were not constant and the emissions were increased. It is also important that (with the existing regulation of the fuel/air ratio that refers to gasoline) the engine functioned for the case of gasoline-methanol mixtures up to a concentration of -70%methanol mixture, while for the case of gasoline-ethanol mixtures until the use of 100%ethanol. Furthermore, during the use of the mixtures of gasoline-methanol and gasoline-ethanol there was a small increase of fuel consumption when the percentage of the methanol or ethanol in the fuel was increased. PMID:14599140

  6. Influence of the High?Frequency Capacitive Discharge Regimes on the Parameters of the Plasma in N 2 \\/CO 2 \\/He Gas Mixtures

    Microsoft Academic Search

    V. V. Azharonok; I. I. Filatova; V. D. Shimanovich; L. N. Orlov

    2002-01-01

    The optical radiation spectra and the spatial structure of a planar high-frequency capacitive discharge in N2\\/CO2\\/He gas mixtures have been investigated depending on the excitation frequency, discharge current, pressure, and chemical composition of the mixture.

  7. K-distribution models for gas mixtures in hypersonic nonequilibrium flows

    NASA Astrophysics Data System (ADS)

    Bansal, Ankit

    Calculation of nonequilibrium radiation field in plasmas around a spacecraft entering into an atmosphere at hypersonic velocities is a very complicated and computationally expensive task. The objective of this Dissertation is to collect state-of-the art spectroscopic data for the evaluation of spectral absorption and emission coefficients of atomic and molecular gases, develop efficient and accurate spectral models and databases, and study the effect of radiation on wall heat loads and flowfield around the spacecraft. The most accurate simulation of radiative transport in the shock layer requires calculating the gas properties at a large number of wavelengths and solving the Radiative Transfer Equation (RTE) in a line-by-line (LBL) fashion, which is prohibitively expensive for coupled simulations. A number of k-distribution based spectral models are developed for atomic lines, continuum and molecular bands that allow efficient evaluation of radiative properties and heat loads in hypersonic shock layer plasma. Molecular radiation poses very different challenges than atomic radiation. A molecular spectrum is governed by simultaneous electronic, vibrational and rotational transitions, making the spectrum very strongly dependent on wavelength. In contrast to an atomic spectrum, where line wings play a major role in heat transfer, most of the heat transfer in molecular spectra occurs near line centers. As the first step, k-distribution models are developed separately for atomic and molecular species, taking advantage of the fact that in the Earth's atmosphere the radiative field is dominated by atomic species (N and O) and in Titan's and Mars' atmospheres molecular bands of CN and CO are dominant. There are a number of practical applications where both atomic and molecular species are present, for example, the vacuum-ultra-violet spectrum during Earth's reentry conditions is marked by emission from atomic bound-bound lines and continuum and simultaneous absorption by strong bands of N2. For such cases, a new model is developed for the treatment of gas mixtures containing atomic lines, continuum and molecular bands. Full-spectrum k-distribution (FSK) method provides very accurate results compared to those obtained from the exact line-by-line method. For cases involving more extreme gradients in species concentrations and temperature, full-spectrum k-distribution model is relatively less accurate, and the method is refined by dividing the spectrum into a number of groups or scales, leading to the development of multi-scale models. The detailed methodology of splitting the gas mixture into scales is presented. To utilize the full potential of the k-distribution methods, pre-calculated values of k-distributions are stored in databases, which can later be interpolated at local flow conditions. Accurate and compact part-spectrum k-distribution databases are developed for atomic species and molecular bands. These databases allow users to calculate desired full-spectrum k-distributions through look-up and interpolation. Application of the new spectral models and databases to shock layer plasma radiation is demonstrated by solving the radiative transfer equation along typical one-dimensional flowfields in Earth's, Titan's and Mars' atmospheres. The k-distribution methods are vastly more efficient than the line-by-line method. The efficiency of the method is compared with the line-by-line method by measuring computational times for a number of test problems, showing typical reduction in computational time by a factor of more than 500 for property evaluation and a factor of about 32,000 for the solution of the RTE. A large percentage of radiative energy emitted in the shock-layer is likely to escape the region, resulting in cooling of the shock layer. This may change the flow parameters in the flowfield and, in turn, can affect radiative as well as convective heat loads. A new flow solver is constructed to simulate coupled hypersonic flow-radiation over a reentry vehicle. The flow solver employs a number of existing schemes and tools av

  8. Detection of brown adipose tissue and thermogenic activity in mice by hyperpolarized xenon MRI

    PubMed Central

    Branca, Rosa Tamara; He, Ting; Zhang, Le; Floyd, Carlos S.; Freeman, Matthew; White, Christian; Burant, Alex

    2014-01-01

    The study of brown adipose tissue (BAT) in human weight regulation has been constrained by the lack of a noninvasive tool for measuring this tissue and its function in vivo. Existing imaging modalities are nonspecific and intrinsically insensitive to the less active, lipid-rich BAT of obese subjects, the target population for BAT studies. We demonstrate noninvasive imaging of BAT in mice by hyperpolarized xenon gas MRI. We detect a greater than 15-fold increase in xenon uptake by BAT during stimulation of BAT thermogenesis, which enables us to acquire background-free maps of the tissue in both lean and obese mouse phenotypes. We also demonstrate in vivo MR thermometry of BAT by hyperpolarized xenon gas. Finally, we use the linear temperature dependence of the chemical shift of xenon dissolved in adipose tissue to directly measure BAT temperature and to track thermogenic activity in vivo. PMID:25453088

  9. Detection of brown adipose tissue and thermogenic activity in mice by hyperpolarized xenon MRI.

    PubMed

    Branca, Rosa Tamara; He, Ting; Zhang, Le; Floyd, Carlos S; Freeman, Matthew; White, Christian; Burant, Alex

    2014-12-16

    The study of brown adipose tissue (BAT) in human weight regulation has been constrained by the lack of a noninvasive tool for measuring this tissue and its function in vivo. Existing imaging modalities are nonspecific and intrinsically insensitive to the less active, lipid-rich BAT of obese subjects, the target population for BAT studies. We demonstrate noninvasive imaging of BAT in mice by hyperpolarized xenon gas MRI. We detect a greater than 15-fold increase in xenon uptake by BAT during stimulation of BAT thermogenesis, which enables us to acquire background-free maps of the tissue in both lean and obese mouse phenotypes. We also demonstrate in vivo MR thermometry of BAT by hyperpolarized xenon gas. Finally, we use the linear temperature dependence of the chemical shift of xenon dissolved in adipose tissue to directly measure BAT temperature and to track thermogenic activity in vivo. PMID:25453088

  10. On the analysis of CO 2 , H 2 - and CO, H 2 -mixtures by water-gas potentiometry with solid electrolyte cells

    Microsoft Academic Search

    Reinhold Hartung

    1996-01-01

    The potentiometric analysis of CO2, H2 and CO, H2O-mixtures using oxide ion-conducting solid electrolytes requires the adjustment of the water-gas equilibrium without side\\u000a reactions in the high-temperature galvanic cell. Conventional cell designs suitable for the analysis of H2, H2O and CO, CO2-mixtures are not applicable due to the insufficient gas residence times in the cells and the insufficient catalytical activity

  11. Design of Solid Form Xenon124 Target for Producing I-123 Radioisotope Using Computer Simulation Techniques

    Microsoft Academic Search

    K. Kamali Moghaddam; M. Sadeghi; T. Kakavand; S. Shokri Bonab

    2006-01-01

    Recently in Cyclotron and Nuclear Medicine Department of NRCAM, at Atomic Energy organization of Iran (AEOI), a system for producing 1-123 via Xe-124 gas target technology, has been constructed and installed. One of the major problems in this system is the highly expensive cost of the enriched Xenon-124 gas. Therefore, saving this gas inside the system is very important. Unfortunately,

  12. Effect of hydrogen ratio on plasma parameters of N{sub 2}-H{sub 2} gas mixture glow discharge

    SciTech Connect

    El-Brulsy, R. A.; Abd Al-Halim, M. A.; Abu-Hashem, A. [Benha University, Physics Department, Faculty of Science (Egypt); Rashed, U. M. [Alazhar University, Physics Department, Faculty of Science (Egypt); Hassouba, M. A. [Benha University, Physics Department, Faculty of Science (Egypt)

    2012-05-15

    A dc plane glow discharge in a nitrogen-hydrogen (N{sub 2}-H{sub 2}) gas mixture has been operated at discharge currents of 10 and 20 mA. The electron energy distribution function (EEDF) at different hydrogen concentrations is measured. A Maxwellian EEDF is found in the positive column region, while in both cathode fall and negative glow regions, a non-Maxwellian one is observed. Langmuir electric probes are used at different axial positions, gas pressures, and hydrogen concentrations to measure the electron temperature and plasma density. The electron temperature is found to increase with increasing H{sub 2} concentration and decrease with increasing both the axial distance from the cathode and the mixture pressure. At first, with increasing distance from the cathode, the ion density decreases, while the electron density increases; then, as the anode is further approached, they remain nearly constant. At different H{sub 2} concentrations, the electron and ion densities decrease with increasing the mixture pressure. Both the electron and ion densities slightly decrease with increasing H{sub 2} concentration.

  13. Condensation from gas–vapour mixtures in small non-circular tubes

    Microsoft Academic Search

    S. Krishnaswamy; H. S. Wang; J. W. Rose

    2006-01-01

    Careful measurements have been made during condensation of steam from steam–air mixtures flowing in a small, flattened, horizontal tube. The ranges of the relevant variables covered (inlet temperature, pressure, air mole fraction and mixture mass flow rate) were chosen to simulate those occurring in an exhaust heat-exchanger tube of a proposed fuel-cell engine. The experimental tube was cooled by water

  14. The effects of the use of different shielding gas mixtures in laser welding of metals

    Microsoft Academic Search

    M. H. Glowacki

    1995-01-01

    The paper makes use of the solution of the system of Saha equations derived for any mixture of ionized monatomic gases. This solution is specifically applied to the case of two-component mixtures of the gases used as shields in the process of laser welding, namely Ar plus He, Ar plus O2, Ar plus N2 and Ar plus H2. The number

  15. Nucleate pool boiling of liquid methane and its natural gas mixtures

    Microsoft Academic Search

    Maoqiong Gong; Jia Ma; Jianfeng Wu; Yu Zhang; Zhaohu Sun; Yuan Zhou

    2009-01-01

    An apparatus was designed and built for the study on pool-boiling heat transfer characteristics of pure and mixed fluids at cryogenic temperature. With this apparatus, extensive measurements were carried out to investigate the pool-boiling behaviors of pure methane and three binary mixtures of methane+ethane, methane+propane and methane+isobutane, as well as a multicomponent mixture of methane, ethane, propane and isobutane. The

  16. Monitoring Xenon in the Breathing Circuit with a Thermal Conductivity Sensor

    Microsoft Academic Search

    Martin Luginbühl; Rolf Lauber; Peter Feigenwinter; Alex M. Zbinden

    2002-01-01

    Objective. To test the accuracy of a thermal conductivityxenon sensor in vitroand in vivoand totest the effect of xenon on other anesthetic gas analyzers as determinedby a mass spectrometry gold standard. Methods.The xenonconcentration was measured with a prototype of a thermal conductivitysensor and a mass spectrometer in vitroand in6 patients. Further in vitroexperiments determinedthe impact of xenon on the measurements of oxygen, carbon dioxide anddesflurane with

  17. Xenon NMR studies of dynamics and exchange in zeolites

    SciTech Connect

    Moudrakovski, I.L.; Ratcliffe, C.I.; Ripmeester, J.A. [Steacie Institute for Molecular Sciences, Ottawa, Ontario (Canada)

    1996-10-01

    We have found, despite earlier reports to the contrary, that for many microporous solids with one-dimensional channels (ZSM-12, ALPO-5, VPI-5, SSZ-24) the chemical shift has an anisotropic component. For ALPO-11, a detailed model has been developed which accounts for the loading-dependent chemical shift in terms of intraparticle exchange of statistical distributions of xenon atoms with 0, 1 or 2 nearest neighbors. A similar model can be applied to ZSM-12 up to moderate loadings. At higher loading levels 2D exchange methods show that interparticle exchange occurs as well. The same approach was used to study interparticle exchange in X and Y zeolite mixtures, exchange amongst zeolite clusters of up to 8 xenon atoms in the supercages of AgA zeolite, and main channel - side pocket exchange in mordenite. The parameters derived are directly relevant to the understanding of sorption and diffusion processes in zeolites.

  18. Gas dynamic aspects of silicon thin layers deposition using excitation of a free jet of the working gas mixture by an electron beam

    NASA Astrophysics Data System (ADS)

    Skovorodko, P. A.; Sharafutdinov, R. G.; Shchukin, V. G.; Konstantinov, V. O.

    2012-11-01

    A film of microcrystalline silicon (?c-Si:H) deposited at low temperature is a promising material for thin-film silicon solar cells with high efficiency and high stability. To deposit silicon thin films with high deposition rate and high quality, a novel gas-jet deposition method has been developed. The paper is devoted to experimental and numerical study of the method from the gas dynamic point of view. A numerical model of the flow field of the working gas mixture in the device was developed that provides predictions of the film thickness distribution over the substrate surface and was found to describe the measured data satisfactory. The model may be used to optimize the operating parameters of the device.

  19. Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with neon

    NASA Astrophysics Data System (ADS)

    Malinina, A. A.; Malinin, A. N.

    2013-12-01

    Results are presented from studies of the optical characteristics and parameters of plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with neon—the working medium of a non-coaxial exciplex gas-discharge emitter. The electron energy distribution function, the transport characteristics, the specific power losses for electron processes, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering by the working mixture components are determined as functions of the reduced electric field. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules is found to be 1.6 × 10-14 m3/s for a reduced electric field of E/ N = 15 Td, at which the maximum emission intensity in the blue-green spectral region (?max = 502 nm) was observed in this experiment.

  20. A hybrid wide-band correlated-k weighted-sum-of-gray-gas model for radiative transfer in non-homogeneous gas mixtures

    SciTech Connect

    Denison, M.K.; Fiveland, W.A.

    1997-07-01

    A hybrid model is presented which draws on the strengths of the correlated k-distribution (c-k) method and the weighted-sum-of-gray-gases (WSGG) model. A simple function for the reordered wave number within wide bands is used which closely approximates the widely used four-region expression. The model handles mixtures of three or more species by the use of a composite wide band spectrum of the gas mixture requiring only a single quadrature of radiative solutions regardless of the number of species. Overlapping wide bands of differing species are combined and treated as single equivalent wide bands. The model is first evaluated by comparing total emissivities of gas mixtures with those of wide band block calculations. The model predictions are then compared with c-k calculations in problems of non-isothermal media. The model predicts higher intensities than those of the band-by-band c-k method in spatial regions of high temperature gradients. The model is quite efficient compared to the c-k method, requiring only three or four solutions of the radiative transfer equation (RTE).

  1. Xenon is an inhibitor of tissue-plasminogen activator: adverse and beneficial effects in a rat model of thromboembolic stroke

    PubMed Central

    David, Hélène N; Haelewyn, Benoît; Risso, Jean-Jacques; Colloc'h, Nathalie; Abraini, Jacques H

    2010-01-01

    Preclinical evidence in rodents has proven that xenon may be a very promising neuroprotective agent for treating acute ischemic stroke. This has led to the general thinking that clinical trials with xenon could be initiated in acute stroke patients in a next future. However, an unappreciated physicochemical property of xenon has been that this gas also binds to the active site of a series of serine proteases. Because the active site of serine proteases is structurally conserved, we have hypothesized and investigated whether xenon may alter the catalytic efficiency of tissue-type plasminogen activator (tPA), a serine protease that is the only approved therapy for acute ischemic stroke today. Here, using molecular modeling and in vitro and in vivo studies, we show (1) xenon is a tPA inhibitor; (2) intraischemic xenon dose dependently inhibits tPA-induced thrombolysis and subsequent reduction of ischemic brain damage; (3) postischemic xenon virtually suppresses ischemic brain damage and tPA-induced brain hemorrhages and disruption of the blood–brain barrier. Taken together, these data indicate (1) xenon should not be administered before or together with tPA therapy; (2) xenon could be a golden standard for treating acute ischemic stroke if given after tPA-induced reperfusion, with both unique neuroprotective and antiproteolytic (anti-hemorrhaging) properties. PMID:20087367

  2. Effects of hydrogen-natural gas mixtures in a distribution system: a practical approach

    Microsoft Academic Search

    D. C. Nielsen; W. S. Ku; C. R. Guerra

    1979-01-01

    Cocombustion tests conducted by Public Service Electric Gas Co. with hydrogen\\/natural gas blends determined the maximum amount of hydrogen that can be mixed with pipeline gas to maintain the performance reliability and efficiency of typical residential burners. Blends of up to 15% hydrogen are operationally feasible in terms of combustion characteristics, pressure requirements, and leakage potential. A combination utility such

  3. Effect of flow velocity and temperature on ignition characteristics in laser ignition of natural gas and air mixtures

    NASA Astrophysics Data System (ADS)

    Griffiths, J.; Riley, M. J. W.; Borman, A.; Dowding, C.; Kirk, A.; Bickerton, R.

    2015-03-01

    Laser induced spark ignition offers the potential for greater reliability and consistency in ignition of lean air/fuel mixtures. This increased reliability is essential for the application of gas turbines as primary or secondary reserve energy sources in smart grid systems, enabling the integration of renewable energy sources whose output is prone to fluctuation over time. This work details a study into the effect of flow velocity and temperature on minimum ignition energies in laser-induced spark ignition in an atmospheric combustion test rig, representative of a sub 15 MW industrial gas turbine (Siemens Industrial Turbomachinery Ltd., Lincoln, UK). Determination of minimum ignition energies required for a range of temperatures and flow velocities is essential for establishing an operating window in which laser-induced spark ignition can operate under realistic, engine-like start conditions. Ignition of a natural gas and air mixture at atmospheric pressure was conducted using a laser ignition system utilizing a Q-switched Nd:YAG laser source operating at 532 nm wavelength and 4 ns pulse length. Analysis of the influence of flow velocity and temperature on ignition characteristics is presented in terms of required photon flux density, a useful parameter to consider during the development laser ignition systems.

  4. Laser flash-photolysis and gas discharge in N2O-containing mixture: kinetic mechanism

    NASA Astrophysics Data System (ADS)

    Kosarev, Ilya; Popov, Nikolay; Starikovskaia, Svetlana; Starikovskiy, Andrey; mipt Team

    2011-10-01

    The paper is devoted to further experimental and theoretical analysis of ignition by ArF laser flash-photolysis and nanosecond discharge in N2O-containing mixture has been done. Additional experiments have been made to assure that laser emission is distributed uniformly throughout the cross-section. The series of experiments was proposed and carried out to check validity of O(1D) determination in experiments on plasma assisted ignition initiated by flash-photolysis. In these experiments, ozone density in the given mixture (mixture composition and kinetics has been preliminary analyzed) was measured using UV light absorption in Hartley band. Good coincidence between experimental data and results of calculations have been obtained Temporal behavior of energy input, electric field and electric current has been measured and analyzed. These data are considered as initial conditions for numerical modeling of the discharge in O2:N2O:H2:Ar = 0.3:1:3:5 mixture. Ion-molecular reactions and reactions of active species production in Ar:H2:O2:N2O mixture were analyzed. The set of reactions to describe chemical transformation in the system due to the discharge action has been selected.

  5. Dynamic mean field theory for lattice gas models of fluid mixtures confined in mesoporous materials.

    PubMed

    Edison, J R; Monson, P A

    2013-11-12

    We present the extension of dynamic mean field theory (DMFT) for fluids in porous materials (Monson, P. A. J. Chem. Phys. 2008, 128, 084701) to the case of mixtures. The theory can be used to describe the relaxation processes in the approach to equilibrium or metastable equilibrium states for fluids in pores after a change in the bulk pressure or composition. It is especially useful for studying systems where there are capillary condensation or evaporation transitions. Nucleation processes associated with these transitions are emergent features of the theory and can be visualized via the time dependence of the density distribution and composition distribution in the system. For mixtures an important component of the dynamics is relaxation of the composition distribution in the system, especially in the neighborhood of vapor-liquid interfaces. We consider two different types of mixtures, modeling hydrocarbon adsorption in carbon-like slit pores. We first present results on bulk phase equilibria of the mixtures and then the equilibrium (stable/metastable) behavior of these mixtures in a finite slit pore and an inkbottle pore. We then use DMFT to describe the evolution of the density and composition in the pore in the approach to equilibrium after changing the state of the bulk fluid via composition or pressure changes. PMID:24102541

  6. Gas-liquid-liquid equilibria in mixtures of water, light gases, and hydrocarbons

    SciTech Connect

    Chao, K.C.

    1990-01-01

    Phase equilibrium in mixtures of water + light gases and water + heavy hydrocarbons has been investigated with the development of new local composition theory, new equations of state, and new experimental data. The preferential segregation and orientation of molecules due to different energies of molecular interaction has been simulated with square well molecules. Extensive simulation has been made for pure square well fluids and mixtures to find the local composition at wide ranges of states. A theory of local composition has been developed and an equation of state has been obtained for square well fluids. The new local composition theory has been embedded in several equations of state. The pressure of water is decoupled into a polar pressure and non-polar pressure according to the molecular model of water of Jorgensen et al. The polar pressure of water is combined with the BACK equation for the general description of polar fluids and their mixtures. Being derived from the steam table, the Augmented BACK equation is particularly suited for mixtures of water + non-polar substances such as the hydrocarbons. The hydrophobic character of the hydrocarbons had made their mixtures with water a special challenge. A new group contribution equation of state is developed to describe phase equilibrium and volumetric behavior of fluids while requiring only to know the molecular structure of the components. 15 refs., 1 fig.

  7. Deactivation of the xenon atom in the 6s metastable state in collisions with xenon and helium atoms

    SciTech Connect

    Zayarnyi, D A; Semenova, Ludmila V; Ustinovskii, N N; Kholin, I V; Chugunov, A Yu [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    1998-03-31

    The absorption probing method was used to investigate collisional deactivation of the metastable 6s[3/2]{sub 2}{sup 0}({sup 3}P{sub 2}) state of the xenon atom in high-pressure He - Xe mixtures with a low xenon concentration. Measurements were made of the rate constants of the plasma-chemical reactions Xe*+Xe+He {yields} Xe{sub 2}*+He [(1.7 {+-}0.2) x10{sup -32} cm{sup 6} s{sup -1}], Xe*+2He{yields} HeXe*+He (less than 3 x 10{sup -35} cm{sup 6} s{sup -1}), and Xe*+He{yields} products+He (less than 10{sup -15} cm{sup 3} s{sup -1}). (active media)

  8. Numerical study on xenon positive column discharges of mercury-free lamp

    SciTech Connect

    Ouyang, Jiting; He, Feng; Miao, Jinsong; Wang, Jianqi; Hu, Wenbo [School of Science, Beijing Institute of Technology, P.O. Box 327, Beijing 100081 (China); Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049 (China)

    2007-02-15

    In this paper, the numerical study has been performed on the xenon positive column discharges of mercury-free fluorescent lamp. The plasma discharge characteristics are analyzed by numerical simulation based on two-dimensional fluid model. The effects of cell geometry, such as the dielectric layer, the electrode width, the electrode gap, and the cell height, and the filling gas including the pressure and the xenon percentage are investigated in terms of discharge current and discharge efficiency. The results show that a long transient positive column will form in the xenon lamp when applying ac sinusoidal power and the lamp can operate in a large range of voltage and frequency. The front dielectric layer of the cell plays an important role in the xenon lamp while the back layer has little effect. The ratio of electrode gap to cell height should be large to achieve a long positive column xenon lamp and higher efficiency. Increase of pressure or xenon concentration results in an increase of discharge efficiency and voltage. The discussions will be helpful for the design of commercial xenon lamp cells.

  9. High-rate reactive ion etching of barium hexaferrite films using optimal CHF3/SF6 gas mixtures

    NASA Astrophysics Data System (ADS)

    Chen, Zhaohui; Yang, Aria; Xie, Changqing; Yang, Qinghua; Vittoria, C.; Harris, V. G.

    2009-03-01

    The high-rate reactive ion etching of c-axis oriented quasi-single-crystal barium hexaferrite (BaM) films, deposited on 6-H silicon carbide (0001) substrates, has been demonstrated. Arrays of BaM columns, having diameters of 1-4 ?m and sharp vertical walls, were etched from BaM films at rates as high as 75 nm/min using an optimized sulfur hexafluoride and methyl trifluoride (SF6:CHF3, 3:1) gas mixture. Lateral features as small as 43 nm were fabricated and imaged.

  10. Modeling Pulse Characteristics in Xenon with NEST

    E-print Network

    Mock, Jeremy; Kazkaz, Kareem; Szydagis, Matthew; Tripathi, Mani; Uvarov, Sergey; Woods, Michael; Walsh, Nicholas

    2013-01-01

    A comprehensive model for describing the characteristics of pulsed signals, generated by particle interactions in xenon detectors, is presented. An emphasis is laid on two-phase time projection chambers, but the models presented are also applicable to single phase detectors. In order to simulate the pulse shape due to primary scintillation light, effects such as the ratio of singlet and triplet dimer state populations, as well as their corresponding decay times, and the recombination time are incorporated into the model. In a two phase time projection chamber, when simulating the pulse caused by electroluminescence light, parameters such as ionization electron mean free path in gas, the drift velocity, singlet and triplet decay times, diffusion constants, and the electron trapping time, have been implemented. This modeling has been incorporated into a complete software package, which realistically simulates the expected pulse shapes for these types of detectors.

  11. Modeling pulse characteristics in Xenon with NEST

    NASA Astrophysics Data System (ADS)

    Mock, J.; Barry, N.; Kazkaz, K.; Stolp, D.; Szydagis, M.; Tripathi, M.; Uvarov, S.; Woods, M.; Walsh, N.

    2014-04-01

    A comprehensive model for describing the characteristics of pulsed signals, generated by particle interactions in xenon detectors, is presented. An emphasis is laid on two-phase time projection chambers, but the models presented are also applicable to single phase detectors. In order to simulate the pulse shape due to primary scintillation light, the effects of the ratio of singlet and triplet dimer state populations, as well as their corresponding decay times, and the recombination time are incorporated into the model. In a two phase time projection chamber, when simulating the pulse caused by electroluminescence light, the ionization electron mean free path in gas, the drift velocity, singlet and triplet decay times, diffusion constants, and the electron trapping time, have been implemented. This modeling has been incorporated into a complete software package, which realistically simulates the expected pulse shapes for these types of detectors.

  12. Pulse Shape in 2-Phase Xenon Detectors

    NASA Astrophysics Data System (ADS)

    Mock, Jeremy

    2013-04-01

    Understanding the shape and size of the primary (S1) and secondary (S2) scintillation pulses in noble elements is crucial for discriminating between different particle interactions. Monte Carlo results from NEST (the Noble Element Simulation Technique) will be presented which match the available data from liquid xenon on the dependence of the recombination time, which is a critical piece of the S1 pulse timing structure, on dE/dx, interaction type, and electric field magnitude. In addition, a model for the S2 pulse shape and the dependence of its width on the depth of an interaction in a detector will be presented which takes into account drift speed, the single/triplet time constants, diffusion, thermal electron trapping at a liquid-gas interface, and other effects.

  13. Stable Xenon Nitride at High Pressures

    NASA Astrophysics Data System (ADS)

    Zhang, Yunwei; Peng, Feng; Ma, Yanming

    2015-03-01

    Nitrogen is the most abundant element on Earth and exists as inert N2 molecules in the atmosphere. Noble gas nitrides are missing in nature because N2 molecules do not interact with noble gases at ambient conditions, greatly impeding the understanding of physics and chemistry of such nitrides. We report here a pressure-induced chemical reaction of N2 with xenon predicted using a swarm-structure searching calculation as implemented in the CALYPSO code. This reaction leads to the formation of a hitherto unexpected Xe nitride at megabar pressure accessible to high-pressure experiments. The high-pressure phase with a hypervalent state of Xe by accepting unprecedented Xe-N covalent bonds appears to be the most stable stoichiometry. The Xe bonding situation in this new phase is substantially different from earlier high-pressure examples of ionic Xe bonding or van der Waals interactions.

  14. The adsorption of argon, krypton and xenon on activated charcoal

    SciTech Connect

    Underhill, D.W. [Univ. of South Carolina, Columbia, SC (United States)

    1996-08-01

    Charcoal adsorption beds are commonly used to remove radioactive noble gases from contaminated gas streams. The design of such beds requires the adsorption coefficient for the noble gas. Here an extension of the Dubinin-Radushkevich theory of adsorption is developed to correlate the effects of temperature, pressure, concentration, and carrier gas on the adsorption coefficients of krypton, xenon, and argon on activated carbon. This model is validated with previously published adsorption measurements. It accurately predicts the equilibrium adsorption coefficient at any temperature and pressure if the potential energies of adsorption, the micropore volume, and the van der Waals constants of the gases are known. 18 refs., 4 figs.

  15. Features of radio-frequency alpha-discharges in Co2+N2+He gas mixtures for slab CO2 lasers

    Microsoft Academic Search

    V. V. Azharonok; Igor V. Filatov; V. D. Shimanovich; L. K. Orlov; J. I. Nekrashevich

    2000-01-01

    The outcomes of spectroscopical investigations of RF-discharge plasma parameters are represented for the CO2 laser mixtures. The main emphasis is made on the exploration of spatial instabilities of luminescence intensity and gas temperature distribution in such discharge. Unlike the theoretical prediction it is shown that sizes of the sheath in a RF discharge weakly depend on excitation frequency and gas

  16. Sound waves in monodisperse gas-particle or vapour-droplet mixtures

    Microsoft Academic Search

    N. A. Gumerov; A. I. Ivandaev; R. I. Nigmatulin

    1988-01-01

    A brief review of the relevant papers and an examination of the current status of research in the field of the acoustics of gas-particle suspensions are given. Nonstationary momentum, mass and energy transfer processes between a gas (vapor) and dispersed particles (droplets) under high-frequency acoustic perturbations are considered. A comparative evaluation of characteristic times and temperature differences for gas-particle and

  17. Resist Pattern Reformation by Reactive Ion Etching with Ar+CH4 Gas Mixture and Its Application

    NASA Astrophysics Data System (ADS)

    Watanabe, Iwao

    1984-04-01

    Resist sputter-etching characteristics and deposited film morphology on a fine pattern are investigated in this paper. An Ar+CH4 gas mixture is adopted as the etching gas to combine the sputter-etching with the hydrocarbon film deposition for the reformation of resist pattern. The resist pattern is reformed in this way with no reduction in the resist pattern width. This method forms a high resistance layer on the resist surface, improving dry etching durability of the resist. This method is then applied to a two-layer resist pattern formation process and it is found that submicron pattern can be easily obtained in two-layer (FBM/PMMA) resist.

  18. A numerical program for steady-state flow of magma-gas mixtures through vertical eruptive conduits

    USGS Publications Warehouse

    Mastin, Larry G.; Ghiorso, Mark S.

    2000-01-01

    This report presents a model that calculates flow properties (pressure, vesicularity, and some 35 other parameters) as a function of vertical position within a volcanic conduit during a steady-state eruption. The model idealizes the magma-gas mixture as a single homogeneousfluid and calculates gas exsolution under the assumption of equilibrium conditions. These are the same assumptions on which classic conduit models (e.g. Wilson and Head, 1981) have been based. They are most appropriate when applied to eruptions of rapidly ascending magma (basaltic lava-fountain eruptions, and Plinian or sub-Plinian eruptions of intermediate or silicic magmas) that contains abundant nucleation sites (microlites, for example) for bubble growth.

  19. Problems of interaction of a supersonic gas mixture with a wall solved by the projection method applied to the full Boltzmann equation

    E-print Network

    Raines, Alla

    2015-01-01

    Numerical solution of non-steady problems of supersonic inflow of a binary mixture of a rarefied gas on a normally posed wall with mirror and diffuse reflection laws is obtained on the basis of the kinetic Boltzmann equation for the model of hard sphere molecules. For calculation of collision integrals we apply the projection method, developed by Tcheremissine for a one-component gas and generalized by the author for a binary gas mixture in the case of cylindrical symmetry. We demonstrate a good qualitative agreement of our results with other authors for one-component gases.

  20. Separation of Carbon Dioxide from Natural Gas Mixtures through Polymeric Membranes—A Review

    Microsoft Academic Search

    S. Sridhar; B. Smitha; T. M. Aminabhavi

    2007-01-01

    Various technologies are now available to design engineers to condition raw natural gas to pipeline quality. Conditioning of natural gas involves the removal of acid gases like CO2 and H2S, besides water vapor. Among different separation methods available, membrane technology has emerged to be a viable and valuable option over conventional techniques like amine absorption, in view of its advantages

  1. Study of the hydrophobic cavity of beta-cryptogein through laser-polarized xenon NMR spectroscopy.

    PubMed

    Berthault, Patrick; Huber, Gaspard; Ha, Phuong Thu; Dubois, Lionel; Desvaux, Hervé; Guittet, Eric

    2006-01-01

    The interaction of xenon with beta-cryptogein, a basic 10 kDa protein belonging to the elicitin family, has been studied by using dissolved thermal and laser-polarized gas in liquid-state NMR. 13C and 1H chemical-shift-mapping experiments were unfruitful, the proton lines only experienced a slight narrowing but no significant frequency variation when the xenon concentration was increased. Nevertheless magnetization transfer from hyperpolarized xenon to protons of the protein demonstrates an undoubted interaction and enables localization of the noble-gas-binding site. Due to the proton-proton cross-relaxation efficiency, however, this experiment is subjected to important spin-diffusion. An automatic procedure that takes spin-diffusion into account when assigning the protons that interact with xenon is then used. The binding site, as defined by 30 Xe--H interactions, is situated in the inner core of the protein. The protons that interact with xenon border the channel by which sterols are known to enter into the cavity. These results support the idea that xenon is a good probe for hydrophobic protein regions. PMID:16292784

  2. Reacting gas mixtures in the state-to-state approach: The chemical reaction rates

    NASA Astrophysics Data System (ADS)

    Kustova, Elena V.; Kremer, Gilberto M.

    2014-12-01

    In this work chemically reacting mixtures of viscous flows are analyzed within the framework of Boltzmann equation. By applying a modified Chapman-Enskog method to the system of Boltzmann equations general expressions for the rates of chemical reactions and vibrational energy transitions are determined as functions of two thermodynamic forces: the velocity divergence and the affinity. As an application chemically reacting mixtures of N2 across a shock wave are studied, where the first lowest vibrational states are taken into account. Here we consider only the contributions from the first four single quantum vibrational-translational energy transitions. It is shown that the contribution to the chemical reaction rate related to the affinity is much larger than that of the velocity divergence.

  3. SF6 reclaimer from SF6\\/N2 mixtures by gas separation with molecular sieving effect

    Microsoft Academic Search

    Mitsuru Toyoda; Hiroshi Murase; Takahiro Imai; Hiromi Naotsuka; Akio Kobayashi; Kazukiyo Takano; Kouichi Ohkuma

    2003-01-01

    This paper discusses the various methods for sulfur hexafluoride (SF6) separation from a mixture of low concentrations of SF6 in N2 pressure swing adsorption (PSA) with a suitable kind of synthetic zeolite, which has the expected molecular sieving effect. This molecular sieving effect, derived from molecular size difference between SF6 and N2, is confirmed by the difference between two equivalent

  4. Separation of hydrocarbon gas mixtures using phenolic resin-based carbon membranes

    Microsoft Academic Search

    Antonio B. Fuertes; Ivan Menendez

    2002-01-01

    Carbon membranes are prepared by the carbonisation of a thin film of phenolic resin deposited on the inner face of an alumina tube. Air oxidative treatments at temperatures in the range of 75–350°C, prior to carbonisation (pre-oxidation) or after carbonisation (post-oxidation) were tested in order to improve the separation characteristics of carbon membranes when used with hydrocarbon mixtures such as

  5. Recoil tritium reaction in rare gas-ethane solid mixtures at ultralow temperature

    Microsoft Academic Search

    Kwang Pill Lee; Yoshiaki Ito; Yoshiteru Fujitani; Tetsuo Miyazaki; Kenji Fueki; Yasuyuki Aratono; Masakatsu Saeki; Enzo Tachikawa

    1986-01-01

    Recoil T atom reactions have been studied in Ar (or Kr or Xe)-CâHâ-DâDâ mixtures at 11-20 and 77 K. The relative yields of hydrogen (HT + DT) increase with a decrease of ethane concentration, while those of ethane (CâHâT + CâDâT) decrease complementarily. The results indicate that hydrogen is formed by both hot and thermal T atoms, while ethane is

  6. Xenon preconditioning: molecular mechanisms and biological effects

    PubMed Central

    2013-01-01

    Xenon is one of noble gases and has been recognized as an anesthetic for more than 50?years. Xenon possesses many of the characteristics of an ideal anesthetic, but it is not widely applied in clinical practice mainly because of its high cost. In recent years, numerous studies have demonstrated that xenon as an anesthetic can exert neuroprotective and cardioprotective effects in different models. Moreover, xenon has been applied in the preconditioning, and the neuroprotective and cardioprotective effects of xenon preconditioning have been investigated in a lot of studies in which some mechanisms related to these protections are proposed. In this review, we summarized these mechanisms and the biological effects of xenon preconditioning. PMID:23305274

  7. Reduced xenon diffusion for quantitative lung studythe role of SF6

    E-print Network

    Walsworth, Ronald L.

    measurements in human alveoli using time-dependent gas diffusion NMR. KEYWORDS: xenon; diffusion; sulfur the development of lung ventilation MRI using laser-polarized noble gases (129 Xe and 3 He),1,2 attention has been given to NMR measures of noble gas diffusion as a new tool for studying lung structure and function.3

  8. Commissioning of a magnetic suspension densitometer for high-accuracy density measurements of natural gas mixtures 

    E-print Network

    Patil, Prashant Vithal

    2009-05-15

    High-accuracy density measurement data are required to validate equations of state (EOS) for use in custody transfer of natural gas through pipelines. The AGA8-DC92 EOS, which is the current industry standard has already ...

  9. A study of quenching reactions for the rare gas metastable atoms with emphasis on Kr (3P2)

    Microsoft Academic Search

    J. H. Kolts

    1978-01-01

    The decay constants for Ar(3P0), Ar(3P2), Kr(3P2) and Xe(3P2) in pure argon carrier gas were measured, as well as total quenching rate constants for the reaction of Kr(3P2) with several halogen and nonhalogen containing molecules. The flowing afterglow technique was used; the metastable atoms were produced by passing either pure argon or a mixture of krypton or xenon in argon

  10. Titan's atmospheric chemistry: Photolysis of gas mixtures containing hydrogen cyanide and carbon monoxide at 185 and 254 nm

    NASA Astrophysics Data System (ADS)

    Tran, Buu N.; Force, Michael; Briggs, Robert G.; Ferris, James P.; Persans, Peter; Chera, John J.

    2008-01-01

    The formation of organic compounds in the atmosphere of Titan is an ongoing process of the generation of complex organics from the simplest hydrocarbon, methane. Solar radiation and magnetosphere electrons are the main energy sources that drive the reactions in Titan's atmosphere. Since energy from solar radiation is 200 times greater than that from magnetosphere electrons, we have investigated the products formed by the action of UV radiation (185 and 254 nm) on a mixture of gases containing nitrogen, methane, hydrogen, acetylene, ethylene, and cyanoacetylene, the basic gas mixture (BGM) that simulates aspects of Titan's atmosphere using a flow reactor [Tran, B.N., Ferris, J.P., Chera, J.J., 2003a. Icarus 162, 114-124; Tran, B.N., Joseph, J.C., Force, M., Briggs, R.G., Vuitton, V., Ferris, J.P., 2005. Icarus 177, 106-115]. The present research extends these studies by the addition of carbon monoxide and hydrogen cyanide to the BGM. Quantum yields for the loss of reactants and the formation of volatile products were determined and compared with those measured in the absence of the hydrogen cyanide and carbon monoxide. The GCMS analyses of the volatile photolysis products from the BGM, with added hydrogen cyanide, had a composition similar to that of the BGM while the photolysis products of the BGM with added carbon monoxide contained many oxygenated compounds. The infrared spectrum of the corresponding solid product revealed the absorption band of a ketone group, which was probably formed from the reaction of carbon monoxide with the free radicals generated by photolysis of acetylene and ethylene. Of particular interest was the observation that the addition of HCN to the gas mixture only resulted in a very small change in the C/N ratio and in the intensity of the C tbnd N frequency at 2210 cm -1 in the infrared spectrum suggesting that little HCN is incorporated into the haze analog. The C/N ratio of the haze analogs was found to be in the 10-12 range. The UV spectra of the solid products formed when HCN or CO added to the BGM is similar to the UV absorption formed from the BGM alone. This result is consistent with absence of additional UV chromophores to the solid product when these mixtures are photolyzed. The following photoproducts, which were not starting materials in our photochemical studies, have been observed on Titan: acetonitrile, benzene, diacetylene, ethane, propene, propane, and propyne.

  11. [Hypoxic gas mixture delivery due to a defective vaporiser manifold: case report, review of the literature and suggested emergency management algorithm].

    PubMed

    Berlet, T

    2014-04-01

    A case of delivery of a hypoxic gas mixture to a patient during total intravenous anesthesia is described. A progressive fall in inspiratory oxygen concentration followed by a drop in oxygen saturation below 90?% occurred during the advanced stages of a hitherto uneventful general anesthesia of a female patient undergoing anterior cervical fusion surgery. A malfunctioning defective rubber seal of a vaporizer manifold was identified as the cause of the gas leak. The leak had not been detected during the preanesthesia leak test. The problem of hypoxic gas mixtures and uncommon leaks in modern anesthesia equipment is discussed. The importance of locating a leak in the high or low pressure circuits is explained. An algorithm for the management of an unexpected decrease of inspiratory oxygen concentration or any other manifestation of a gas leak along with a systematic approach to locating the source of a gas leak is presented. PMID:24584839

  12. Shock wave formation in flame propagation in a gas-air mixture within a tube

    SciTech Connect

    Abinov, A.G.; Plotnikov, V.M.; Shebeko, Yu.N.; Eremenko, O.Ya.; Fialkov, B.S.; Muravlev, V.K.; Abramovich, A.L.; Chekhovskikh, A.M.

    1987-07-01

    Attention is given to determination of the inter-relationship of shock and pressure wave parameters (pressure and wave impulse) with the energy contained in the explosive cloud. The experiments were performed in shock tubes. Oscillograms are shown for the cases of strong (blasting cord) and weak (copper wire fuse) initiation. The dependence of shock-wave impulse for strong initiation on the reserve of chemical energy contained in the explosive mixture and on the cross-sectional area of the tube is give. The analogous relationships for weak initiation are shown and interpreted.

  13. Sound Absorption in Molecular Gas Mixtures: Master Equation for Rotational and Vibrational Excitation, Relaxation, and Energy Transfer

    NASA Astrophysics Data System (ADS)

    Huestis, D. L.

    2008-12-01

    Laboratory sound absorption measurements provide much of what we know about the vibrational kinetics of air mixtures, forming the core basis for retrieving the altitude profile of water in the mesosphere from infrared emissions between 6.3 and 6.9 ?m. Here we show that sound-absorption and laser-excitation experiments follow exactly the same kinetics, reflect the same underlying reaction rates, and can be vulnerable to similar ambiguities. This has not been obvious because the literature lacks a consistent prescription for calculating the sound absorption frequency spectrum from the reaction rate coefficients. We have developed the first general theoretical formalism for calculating the absolute magnitude of sound absorption per-unit-length, versus sound frequency, for any number of collisional excitation, relaxation, and energy transfer processes, for any mixture of atomic and molecular gases. This new formalism, and the computer code that implements it, provide the first systematic means for inferring collisional rate coefficients from sound absorption measurements in which more than one rotational or vibrational mode is active, such as N2/O2/H2O/CO2 gas mixtures in the laboratory and the atmosphere. When a sound wave travels through a gas, the alternating compression and expansion cycles heat and cool the gas. If the acoustic frequency roughly matches the rate of vibrational relaxation, then the effective vibrational temperature lags behind the translational temperature and the energy in the sound wave is attenuated. The measured frequency of maximum absorption is proportional to the vibrational relaxation rate. In the simplest laser-based experiment, we excite a single molecular level and record its exponential time decay, with the vibrational relaxation rate being proportional to the decay frequency. In both experiments we derive the relaxation rate coefficient from the linear graph versus gas pressure. The technical problem is that any mixture of molecular gases will have more than one relaxation time constant. Thus we write the chemical kinetics master equation as (1) (d/dt) Nm = ?npq [ - kmn?pq Nm Nn + kpq?mn Np Nq ] which has the well-known time-dependent solution given by (2) Nm(t) = ?n Cmn exp(-?n t) where the ?n values are the decay frequencies and the Cmn coefficients depend on how the gas was initially excited. What we have contributed is the frequency-dependent sound absorption solution to Equation (1): (3) cvint(?) = ?nk Wn / (1 + i ?/?n) where cvint(?) is the complex heat capacity (per molecule), ? is the circular sound frequency, 2?f, the ?n are the calculated decay frequencies [as in Equation (2)] and k Wn is the real effective heat capacity for decay mode n. As pointed out by Landau and Teller [Phys. Z. Sowjet. 10, 34-43 (1936)], for a simple case when the decay modes correspond to vibrational modes, Wn is the ordinary heat capacity of the vibrational mode. In the more complicated case involving one or more reversible energy-transfer steps, e.g., water and oxygen, the vibrational modes and the decay modes do not correspond to each other, and we need to use the rate coefficients in Equation (1) to calculate both ?n and Wn.

  14. Internal structure of shock waves in disparate mass mixtures

    NASA Technical Reports Server (NTRS)

    Chung, Chan-Hong; De Witt, Kenneth J.; Jeng, Duen-Ren; Penko, Paul F.

    1992-01-01

    The detailed flow structure of a normal shock wave for a gas mixture is investigated using the direct-simulation Monte Carlo method. A variable diameter hard-sphere (VDHS) model is employed to investigate the effect of different viscosity temperature exponents (VTE) for each species in a gas mixture. Special attention is paid to the irregular behavior in the density profiles which was previously observed in a helium-xenon experiment. It is shown that the VTE can have substantial effects in the prediction of the structure of shock waves. The variable hard-sphere model of Bird shows good agreement, but with some limitations, with the experimental data if a common VTE is chosen properly for each case. The VDHS model shows better agreement with the experimental data without adjusting the VTE. The irregular behavior of the light-gas component in shock waves of disparate mass mixtures is observed not only in the density profile, but also in the parallel temperature profile. The strength of the shock wave, the type of molecular interactions, and the mole fraction of heavy species have substantial effects on the existence and structure of the irregularities.

  15. A program for calculating expansion-tube flow quantities for real-gas mixtures and comparison with experimental results

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III

    1972-01-01

    A computer program written in FORTRAN 4 language is presented which determines expansion-tube flow quantities for real test gases CO2 N2, O2, Ar, He, and H2, or mixtures of these gases, in thermochemical equilibrium. The effects of dissociation and first and second ionization are included. Flow quantities behind the incident shock into the quiescent test gas are determined from the pressure and temperature of the quiescent test gas in conjunction with: (1) incident-shock velocity, (2) static pressure immediately behind the incident shock, or (3) pressure and temperature of the driver gas (imperfect hydrogen or helium). The effect of the possible existence of a shock reflection at the secondary diaphragm of the expansion tube is included. Expansion-tube test-section flow conditions are obtained by performing an isentropic unsteady expansion from the conditions behind the incident shock or reflected shock to either the test-region velocity or the static pressure. Both a thermochemical-equilibrium expansion and a frozen expansion are included. Flow conditions immediately behind the bow shock of a model positioned at the test section are also determined. Results from the program are compared with preliminary experimental data obtained in the Langley 6-inch expansion tube.

  16. Influence of CO2-Ar Mixtures as Shielding Gas on Laser Welding of Al-Mg Alloys

    NASA Astrophysics Data System (ADS)

    Boukha, Zouhair; Sánchez-Amaya, José María; González-Rovira, Leandro; Rio, Eloy Del; Blanco, Ginesa; Botana, Javier

    2013-12-01

    In this study, AA5083 samples were butt welded under a conduction regime with high-power diode laser (HPDL). Various mixtures composed of Ar and CO2 were used as a shielding gas. The influence of the shielding gas composition on the microstructure and on the properties of laser welds was analyzed. The weld beads were deeply characterized by metallographic/microstructural studies, X-ray diffraction (XRD), X-ray energy dispersive spectrometry (X-EDS) chemical analyses, X-ray photoelectron spectra (XPS), microhardness, and tensile strength. The corrosion resistance of laser-remelted surfaces with different CO2/Ar ratios was also estimated by means of electrochemical tests. The addition of CO2 to the shielding gas results in a better weld penetration and oxidizes the weld pool surface. This addition also promotes the migration of Mg toward the surface of weld beads and induces the formation of magnesium aluminates spinel on the welds. The best corrosion resistance result is achieved with 20 pct CO2. The overall results indicate that the addition of small percentage of CO2 to Ar leads to improvements of the mechanical and corrosion properties of the aluminum welds.

  17. Luminescence characteristics of Xe2Cl excimer molecules under pumping the dense Xe—CCl4 gas mixtures with a pulsed electron beam

    NASA Astrophysics Data System (ADS)

    Mis'kevich, A. I.; Jinbo, Guo

    2013-05-01

    Temporal and spectral characteristics of the luminescence of dense Xe—CCl4 gas mixtures of different composition, excited by a 5-ns pulsed electron beam, were measured. The energy of the electrons amounted to 150 keV and the electron beam current pulse amplitude was 5 A. The gas mixtures were used containing Xe (38-700 Torr) and CCl4 (0.03-0.3 Torr). The studies were performed within the wavelength range 200-1200 nm using a MAYA-2000Pro diffraction grating spectrometer and a RIGOL DS 5022 ME fast digital oscilloscope. The luminescence lifetimes of the excimer molecules XeCl* (band with ?max = 308 nm) and Xe2Cl* (band with ?max = 486 nm) were measured, as well as the constants of quenching by the components of the gas mixture for Xe2Cl* molecules. A model of plasma-chemical processes for dense Xe—CCl4 gas mixtures with a very low content of the CCl4 donor is proposed. It is shown that in such 'poor' mixtures Xe2Cl* molecules are mainly produced as a result of recombination of the Xe2+ and Cl- ions.

  18. Analysis of the insulation characteristics of CF3I gas mixtures with Ar, Xe, He, N2, and CO2 using Boltzmann equation method

    NASA Astrophysics Data System (ADS)

    Deng, Yunkun; Xiao, Dengming

    2014-09-01

    The present study is devoted to the calculation of electron swarm parameters, including the reduced effective ionization coefficient, electron mean energy, and electron drift velocity, for the gas mixtures of CF3I with Ar, Xe, He, N2, and CO2. These data are computed by employing the Boltzmann equation method with two-term approximation in the condition of steady-state Townsend (SST) discharge. For the purpose of evaluating the insulation strength of CF3I gas mixtures, values of the limiting field strength (E/N)lim for which the ionization exactly balances the electron attachment are determined from the variation curves of (? - ?)/N. The results indicate that mixtures of CF3I-N2 present the greatest insulation strength among all the combinations for CF3I content varied from 20 to 90%. Furthermore, the gas mixture with 70% CF3I can achieve a very similar dielectric strength to that of SF6. The concerned liquefaction issues are also taken into account to fully assess the possibility of applying CF3I gas mixtures in power equipment as an insulation medium.

  19. The effective ionization coefficients and electron drift velocities in gas mixtures of CF3I with N2 and CO2 obtained from Boltzmann equation analysis

    NASA Astrophysics Data System (ADS)

    Deng, Yun-Kun; Xiao, Deng-Ming

    2013-03-01

    The electron swarm parameters including the density-normalized effective ionization coefficients (?-?)/N and the electron drift velocities Ve are calculated for a gas mixture of CF3I with N2 and CO2 by solving the Boltzmann equation in the condition of a steady-state Townsend (SST) experiment. The overall density-reduced electric field strength is from 100 Td to 1000 Td (1 Td = 10-17 V·cm2), while the CF3I content k in the gas mixture can be varied over the range from 0% to 100%. From the variation of (?-?)/N with the CF3I mixture ratio k, the limiting field strength (E/N)lim for each CF3I concentration is derived. It is found that for the mixtures with 70% CF3I, the values of (E/N)lim are essentially the same as that for pure SF6. Additionally, the global warming potential (GWP) and the liquefaction temperature of the gas mixtures are also taken into account to evaluate the possibility of application in the gas insulation of power equipment.

  20. Evaluation of carrier agents for hyperpolarized xenon MRI

    NASA Technical Reports Server (NTRS)

    Venkatesh, A. K.; Zhao, L.; Balamore, D.; Jolesz, F. A.; Albert, M. S.

    2000-01-01

    Several biocompatible carrier agents, in which xenon is highly soluble and has a long T(1), were tested, and injected in living rats. These included saline, Intralipid suspension, perfluorocarbon emulsion and (129)Xe gas-filled liposomes. The T(1) of (129)Xe in these compounds ranged from 47 to 116 s. Vascular injection of these carrier agents was tolerated well, encouraging their use for further experiments in live animals. In vivo spectra, obtained from gas-filled liposomes and perfluorocarbon solutions, suggest that these carrier agents have potential for use in angiography and perfusion imaging. Copyright 2000 John Wiley & Sons, Ltd.

  1. Collisional {sup 3}He and {sup 129}Xe Frequency Shifts in Rb-Noble-Gas Mixtures

    SciTech Connect

    Ma, Z. L.; Sorte, E. G.; Saam, B. [Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, Utah, 84112-0830 (United States)

    2011-05-13

    The Fermi-contact interaction that characterizes collisional spin exchange of a noble gas with an alkali-metal vapor also gives rise to NMR and EPR frequency shifts of the noble-gas nucleus and the alkali-metal atom, respectively. We have measured the enhancement factor {kappa}{sub 0} that characterizes these shifts for Rb-{sup 129}Xe to be 493{+-}31, making use of the previously measured value of {kappa}{sub 0} for Rb-{sup 3}He. This result allows accurate {sup 129}Xe polarimetry with no need to reference a thermal-equilibrium NMR signal.

  2. Surface diffusion of xenon on Pt(111)

    NASA Astrophysics Data System (ADS)

    Meixner, D. Laurence; George, Steven M.

    1993-06-01

    The surface diffusion of xenon on the Pt(111) surface was investigated using laser induced thermal desorption (LITD) and temperature programmed desorption (TPD) techniques. The surface diffusion coefficient at 80 K decreased dramatically from D=8×10-7 cm2/s at ?=0.05?s to approximately D=2×10-8 cm2/s at ?=?s, where ?s denotes the saturation coverage at 85 K, corresponding to a commensurate monolayer coverage of 5.0×1014 xenon atoms/cm2. This coverage dependence was consistent with attractive interactions between the adsorbed xenon atoms and the existence of two-dimensional condensed phases of xenon on Pt(111). The kinetic parameters for surface diffusion at ?=?s were Edif=1.3±0.1 kcal/mol and D0=1.1×10-4±0.2 cm2/s. The magnitude of Edif at ?=?s represented the combined effect of the intrinsic corrugation of the adsorbate-surface potential and attractive interactions between the adsorbed xenon atoms. LITD experiments at ?=0.25 ?s revealed diffusion kinetic parameters of Edif=1.2±0.2 kcal/mol and D0=3.4×10-4±0.5 cm2/s. The constant Edif at low and high coverage was attributed to the ``breakaway'' of xenon atoms from the edges of condensed phase xenon islands. The coverage dependence of the surface diffusion coefficient for Xe/Pt(111) was explained by a multiple site diffusion mechanism, where collisions with xenon islands limit diffusional motion. Thermal desorption kinetics for xenon on Pt(111) were determined using TPD experiments. Using the variation of heating rates method, the desorption parameters were Edes=6.6±0.2 kcal/mol and ?des=1.3×1013±0.4 s-1, in good agreement with previous studies. The xenon TPD peak shifted to higher temperature versus initial coverage at a fixed heating rate, providing further evidence for attractive interactions between the adsorbed xenon atoms.

  3. Kinetic Effects in Spherical Expanding Flows of Binary-Gas Mixtures

    E-print Network

    Riabov, Vladimir V.

    College, Nashua, New Hampshire, USA ABSTRACT Diffusion effects in the spherical expanding flows of argon-helium temperature, diffusive velocities, and the effectiveness of species separation and ambient gas penetration 2. Stream Velocity and Diffusion Velocities of Argon and Helium in a Spherical Shock Wave

  4. Radiation trapping in an alkali-vapor-noble-gas mixture excited by a strong laser pulse

    Microsoft Academic Search

    N. N. Bezuglov; A. N Klucharev; B. Taratin; T. Stacewicz; A. F Molisch; F. Fuso; M. Allegrini

    1995-01-01

    We analyze the nonlinear, non-stationary radiation trapping process in a cell filled with a noble gas and an alkali vapor excited by a short intense laser pulse. We derive analytical approximations for the total density of the excited atoms, and for the radiation emerging from the cell. The considered lineshapes are pure Doppler, Voigt, and pure Lorentzian profiles. We confirm

  5. Slag and seed deposition on heat exchanger surfaces from gas-droplet mixtures

    Microsoft Academic Search

    K. H. Im; L. W. Carlson; P. M. Chung

    1978-01-01

    Mechanisms of particulate deposition from turbulent streams to solid surfaces are first discussed. Two problems of current interest in MHD application are then analyzed. One is the collection of slag droplets on the interior wall of vertical tubes from the turbulent droplet-laden gas stream. Such processes take place during the cycle of the regenerative heat exchanger used to preheat combustion

  6. Application of Momentum Transfer Theory for Ion and Electron Transport in Pure Gases and in Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Jovanovi?, J. V.; Vrhovac, S. B.

    2004-12-01

    In this paper we have presented two applications of Momentum Transfer Theory (MTT), which were both aimed at obtaining reliable data for modeling of non-equilibrium plasma. Transport properties of ion swarms in presence of Resonant Charge Transfer (RCT) collisions are studied using Momentum Transfer Theory (MTT). Using the developed MTT we tested a previously available anisotropic set of cross-sections for Ar++Ar collisions bay making the comparisons with the available data for the transverse diffusion coefficient. We also developed an anisotropic set of Ne++Ne integral cross-sections based on the available data for mobility, longitudinal and transverse diffusion. Anisotropic sets of cross-sections are needed for Monte Carlo simulations of ion transport and plasma models. Application of Blanc's Law for drift velocities of electrons and ions in gas mixtures at arbitrary reduced electric field strenghts E/n0 was studied theoretically and by numerical examples. Corrections for Blanc's Law that include effects of inelastic collisions were derived. In addition we have derived the common mean energy procedure that was proposed by Chiflikian in a general case both for ions and electrons. Both corrected common E/n0 and common mean energy procedures provide excellent results even for electrons at moderate E/n0 where application of Blanc's Law was regarded as impossible. In mixtures of two gases that have negative differential conductivity (NDC) even when neither of the two pure gases show NDC the Blanc's Law procedure was able to give excellent predictions.

  7. Oxygen/ozone as a medical gas mixture. A critical evaluation of the various methods clarifies positive and negative aspects

    PubMed Central

    2011-01-01

    Besides oxygen, several other gases such as NO, CO, H2, H2S, Xe and O3 have come to age over the past few years. With regards to O3, its mechanisms of action in medicine have been clarified during the last two decades so that now a comprehensive framework for understanding and recommending ozone therapy in various pathologies is available. O3 used within the determined therapeutic window is absolutely safe and more effective than golden standard medications in numerous pathologies, like vascular diseases. However, ozone therapy is mostly in practitioners' hands and some recent developments for increasing cost effectiveness and speed of treatment are neither standardized, nor evaluated toxicologically. Hence, the aim of this article is to emphasize the need to objectively assess the pros and cons of oxygen/ozone as a medical gas mixture in the hope that ozone therapy will be accepted by orthodox medicine in the near future. PMID:22146387

  8. Low-pressure plasma-etching of bulk polymer materials using gas mixture of CF4 and O2

    NASA Astrophysics Data System (ADS)

    Nabesawa, Hirofumi; Hiruma, Takaharu; Hitobo, Takeshi; Wakabayashi, Suguru; Asaji, Toyohisa; Abe, Takashi; Seki, Minoru

    2013-11-01

    In this study, we have proposed a low-pressure reactive ion etching of bulk polymer materials with a gas mixture of CF4 and O2, and have achieved precise fabrication of poly(methyl methacrylate) (PMMA) and perfluoroalkoxy (PFA) bulk polymer plates with high-aspect-ratio and narrow gap array structures, such as, pillar, frustum, or cone, on a nano/micro scale. The effects of the etching conditions on the shape and size of each pillar were evaluated by changing etching duration and the size/material of etching mask. The fabricated PMMA array structures indicate possibilities of optical waveguide and nanofiber array. PFA cone array structures showed super-hydrophobicity without any chemical treatments. Also, polystyrene-coated silica spheres were used as an etching mask for the pillar array structure formation to control the gap between pillars.

  9. Determination of the Relative Two-photon Absorption Cross-section Between Xenon and Hydrogen

    NASA Astrophysics Data System (ADS)

    Elliott, Drew; Scime, Earl; McCarren, Dustin; Vandervort, Robert; Soderholm, Mark

    2014-10-01

    Two-photon Absorption Laser Induced Fluorescence (TALIF) is a non-perturbative method for measuring the density and temperature of neutral hydrogen in a fusion plasma. Calibration of a TALIF system, for absolute density measurements, requires a measurement of a known density of particles under controlled conditions. Since hydrogen is diatomic, hydrogen TALIF system calibration requires measurements of target cold monatomic gas with a two-photon transition from the ground state and fluorescence decay at accessible energies. Here we present single-sided TALIF (angular momentum change of 2) measurements of a new transition in xenon with absorption and emission wavelengths nearly identical to those of the hydrogen TALIF sequence (the n = 3 to n = 2 emission in hydrogen is at 656.27 nm whereas it is at 655.99 nm in xenon). The xenon calibration approach provides the first opportunity for absolute calibration of Doppler-free (angular momentum change of 0) hydrogen TALIF. We first measure the relative TALIF absorption cross section between xenon and krypton and then use the known cross section ratio between the krypton and hydrogen transitions to calculate the relative xenon-hydrogen cross section. Single isotope xenon samples are used to remove the confounding factors of isotopic and hyperfine splitting.

  10. Discharge stabilization studies of CO laser gas mixtures in quasi-steady supersonic flow

    NASA Technical Reports Server (NTRS)

    Srinivasan, G.; Smith, J. A.

    1976-01-01

    Experiments were conducted to study the applicability of a double discharge stabilization scheme in conditions appropriate for high energy CO lasers in supersonic flows. A Ludwieg tube impulse flow facility and a ballasted capacitor bank provided essentially steady flow and discharge conditions (d.c.) for times longer than ten electrode length-flow transit times. Steady, arc-free, volume discharges were produced in a Mach 3 test cavity using an auxiliary discharge to stabilize the main discharge in N2 and He/CO mixture. A signigicant result is the lack of observed plasma E/N changes in response to auxiliary discharge current changes. Also, where glow discharges were obtained, the energy loading achieved was very much less than the threshold level required for laser operation.

  11. Stability of hypersonic reacting stagnation flow of a detonatable gas mixture by dynamical systems analysis

    SciTech Connect

    Tivanov, G.; Rom, J. [Technion-Israel Inst. of Tech., Haifa (Israel)] [Technion-Israel Inst. of Tech., Haifa (Israel)

    1995-12-01

    The stability characteristics of the reacting hypersonic flow of the fuel/oxidizer mixture in the stagnation region of a blunt body are studied. The conditions for oscillations of the combustion front are assumed to be determined mainly by the flow conditions at the stagnation region. The density at the stagnation region is assumed to be constant at hypersonic flow conditions. By assuming a simplified flow model, the time dependent flow equations, including the heat addition due to the chemical reactions, are reduced to a second-order nonlinear differential equation for the instantaneous temperature. The solutions are analyzed assuming a one-step chemical reaction with zero-order and first-order processes using dynamical systems methods. These methods are used to determine the stability boundaries in terms of the flow and chemical reaction parameters. It is shown that the zero-order reaction has nonperiodic solutions that may lead to explosion whereas the first-order and higher-order reactions may have periodic solutions indicating oscillations. The zero-order analysis also reaffirms the requirements for a minimum size blunt body for the establishment of a detonation (in agreement with classical detonation theory) and the first-order analysis indicates a minimum body size for establishment of oscillations. The oscillation frequencies are calculated using the small perturbation approximation for the temperature oscillations. These frequencies are compared with results from published data on spheres and hemisphere cylindrical bodies fired into hydrogen-oxygen and acetylene oxygen mixtures. Very good agreement is found between the measured and calculated results.

  12. A Search for Nonstandard Neutron Spin Interactions using Dual Species Xenon Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Bulatowicz, Michael; Larsen, Michael; Mirijanian, James; Fu, Changbo; Yan, Haiyang; Smith, Erick; Snow, Mike; Walker, Thad

    2012-06-01

    NMR measurements using polarized noble gases can constrain possible exotic spin-dependent interactions involving nucleons. A differential measurement insensitive to magnetic field fluctuations can be performed using a mixture of two polarized species with different ratios of nucleon spin to magnetic moment. We used the NMR cell test station at Northrop Grumman Corporation (NGC) (developed to evaluate dual species xenon vapor cells for the Nuclear Magnetic Resonance Gyroscope) to search for NMR frequency shifts of xenon-129 and xenon-131 when a non-magnetic zirconia rod is modulated near the NMR cell. We simultaneously excited both Xe isotopes and detected free-induction-decay transients. In combination with theoretical calculations of the neutron spin contribution to the nuclear angular momentum, the measurements put a new upper bound on possible monopole-dipole interactions of the neutron for ranges around 1mm. This work is supported by the NGC Internal Research and Development (IRAD) funding, the Department of Energy, and the NSF.

  13. The mobilities of xenon ions in xenon and the derived charge transfer cross section for Xe+(2P3\\/2) ions in xenon

    Microsoft Academic Search

    P. H. Larsen; M. T. Elford

    1986-01-01

    A drift tube of the four-gauze Tyndall-Powell type has been used to obtain accurate mobility data for ground-state Xe+(2P3\\/2) ions, metastable Xe+(2P1\\/2) ions and molecular Xe2+\\/Xe3+ ions in xenon at room temperature (294.1+or-0.2K) over a wide E\\/N range (E is the electric field strength and N is the gas number density). The measurements were made at E\\/N values from 50

  14. Xenon-Photosensitized Formation of Metastable Nitrogen

    Microsoft Academic Search

    William M. Jackson; Milton D. Scheer

    1965-01-01

    Metastable nitrogen molecules are produced by collision with xenon atoms excited with 1470- angstrom radiation. The photolytically excited species were detected by measuring the rate at which electrons were ejected from a gold surface. Hydrogen was shown to be more efficient than helium in quenching the photo-excited xenon atoms.

  15. Xenon-Photosensitized Formation of Metastable Nitrogen.

    PubMed

    Jackson, W M; Scheer, M D

    1965-06-25

    Metastable nitrogen molecules are produced by collision with xenon atoms excited with 1470-A radiation. The photolytically excited species were detected by measuring the rate at which electrons were ejected from a gold surface. Hydrogen was shown to be more efficient than helium in quenching the photo-excited xenon atoms. PMID:17819421

  16. Weird muonium diffusion in solid xenon

    Microsoft Academic Search

    V. G. Storchak; B. F. Kirillov; A. V. Pirogov; V. A. Duginov; V. G. Grebinnik; T. N. Mamedov; V. G. Ol'Shevsky; V. A. Xhukov; J. H. Brewer; G. D. Morris

    1992-01-01

    Muon and muonium spin rotation and relaxation parameters were studied in liquid and solid xenon. The small diamagnetic fraction (~10%) observed in condensed xenon is believed to be Xemu+. The muonium hyperfine frequency was measured for the first time in liquid Xe and was found to be in agreement with the vacuum value. A nonmonotonic temperature dependence of the muonium

  17. Xenon poisoning calculations based on tube power

    Microsoft Academic Search

    Erkman

    1953-01-01

    A method of calculating the steady state xenon poisoning was developed using parameters derived from the power production of individual tubes in the pile. The power of individual tubes was recorded automatically at some of the production piles. The necessary parameter is derived from these data by the use of IBM computers. This method of calculating xenon poisoning eliminates the

  18. Prospects for Barium Tagging in Gaseous Xenon

    SciTech Connect

    Sinclair, D.; /Carleton U. /TRIUMF; Rollin, E.; /Carleton U.; Smith, J.; /Carleton U.; Mommers, A.; /Ottawa U.; Ackerman, N.; /SLAC; Aharmim, B.; /Laurentian U.; Auger, M.; /Bern U., LHEP; Barbeau, P.S.; /Stanford U., Phys. Dept.; Benitez-Medina, C.; /Colorado State U.; Breidenbach, M.; /SLAC; Burenkov, A.; /Moscow, ITEP; Cook, S.; /SLAC; Coppens, A.; /Carleton U.; Daniels, T.; /Massachusetts U., Amherst; DeVoe, R.; /Stanford U., Phys. Dept.; Dobi, A.; /Maryland U.; Dolinski, M.J.; Donato, K.; /Stanford U., Phys. Dept.; Fairbank, W., Jr.; /Colorado State U.; Farine, J.; /Laurentian U.; Giroux, G.; /Bern U., LHEP /Carleton U. /Stanford U., Phys. Dept. /Carleton U. /Laurentian U. /Carleton U. /SLAC /Indiana U. /Indiana U., CEEM /Korea U. /Stanford U., Phys. Dept. /SLAC /Alabama U. /Colorado State U. /Stanford U., Phys. Dept. /Alabama U. /SLAC /Stanford U., Phys. Dept. /Alabama U. /Massachusetts U., Amherst /SLAC /Alabama U. /SLAC /Maryland U. /Moscow, ITEP /Stanford U., Phys. Dept. /Maryland U. /Bern U., LHEP /Laurentian U. /SLAC /Maryland U.

    2012-05-03

    Tagging events with the coincident detection of a barium ion would greatly reduce the background for a neutrino-less double beta decay search in xenon. This paper describes progress towards realizing this goal. It outlines a source that can produce large quantities of Ba++ in gas, shows that this can be extracted to vacuum, and demonstrates a mechanism by which the Ba++ can be efficiently converted to Ba+ as required for laser identification. It is clear from this study that electrospray is a convenient mechanism for producing Ba++ is gas at atmospheric pressure. It is likely that the source will perform just as effectively at higher pressures. Even though the source region has water vapour and methanol vapour at the 0.3% level, there is no evidence for molecular formation. The use of TEA offers an effective method to achieve the charge state conversion. The overall design of the ion extraction from high pressure to vacuum is very similar to the scheme proposed for the final detector and this appears to work well although the efficiency is not yet determined.

  19. Controlling the Neutron Yield from a Small Dense Plasma Focus using Deuterium-Inert Gas Mixtures

    SciTech Connect

    Bures, B. L.; Krishnan, M.; Eshaq, Y. [Alameda Applied Sciences Corp. 626 Whitney St., San Leandro, CA (United States)

    2009-01-21

    The dense plasma focus (DPF) is a well known source of neutrons when operating with deuterium. The DPF is demonstrated to scale from 10{sup 4} n/pulse at 40 kA to >10{sup 12} n/pulse at 2 MA by non-linear current scaling as described in [1], which is itself based on the simple yet elegant model developed by Lee [2]. In addition to the peak current, the gas pressure controls the neutron yield. Recent published results suggest that mixing 1-5% mass fractions of Krypton increase the neutron yield per pulse by more than 10x. In this paper we present results obtained by mixing deuterium with Helium, Neon and Argon in a 500 J dense plasma focus operating at 140 kA with a 600 ns rise time. The mass density was held constant in these experiments at the optimum (pure) deuterium mass density for producing neutrons. A typical neutron yield for a pure deuterium gas charge is 2x10{sup 6}{+-}15% n/pulse. Neutron yields in excess of 10{sup 7}{+-}10% n/pulse were observed with low mass fractions of inert gas. Time integrated optical images of the pinch, soft x-ray measurements and optical emission spectroscopy where used to examine the pinch in addition to the neutron yield monitor and the fast scintillation detector. Work supported by Domestic Nuclear Detection Office under contract HSHQDC-08-C-00020.

  20. Emission of mercury monobromide exciplex in gas-discharge plasma based on mixture of mercury dibromide vapor with sulfur hexafluoride and helium

    NASA Astrophysics Data System (ADS)

    Malinina, A. A.; Shuaibov, A. K.

    2011-02-01

    We present the results of investigations of an emission of a mercury monobromide exciplex in gas-discharge plasma of an atmospheric pressure barrier discharge based on a mixture of mercury dibromide vapor, sulfur hexafluoride, and helium. We optimized the emission power of mercury monobromide exciplexes with respect to the partial pressures of the working mixture. An average emission power of 0.42 W (?max = 502 nm) is achieved in a cylindrical emission source with a small working volume (0.8 cm3) at a pumping pulse repetition rate of 6 kHz. We determined electron energy distribution functions, transport characteristics, specific discharge power losses for electron processes, electron concentration and temperature, as well as rate constants of elastic and inelastic scattering of electrons by components of the working mixture in relation to the ratio of the field strength to the total concentration of components of the working mixture. We discuss processes that increase the population of the mercury monobromide exciplex. Gas-discharge plasma created in a mixture of mercury dibromide vapor with sulfur hexafluoride and helium can be used as a working medium of an emission source in the blue-green spectral range for the use in scientific research in biotechnology, photonics, and medicine, as well as for creating indicator gas-discharge panels.

  1. Nature of unresolved complex mixture in size-distributed emissions from residential wood combustion as measured by thermal desorption-gas chromatography-mass spectrometry

    Microsoft Academic Search

    Michael D. Hays; N. Dean Smith; Yuanji Dong

    2004-01-01

    Unresolved complex mixture (UCM) is an analytical artifact of gas chromatographs of combustion source-related fine aerosol extracts. In this study the UCM is examined in size-resolved fine aerosol emissions from residential wood combustion. The aerosols are sorted by size in an electrical low-pressure impactor (ELPI) and subsequently analyzed by thermal desorption\\/gas chromatography\\/mass spectrometry (TD\\/GC\\/MS). A semiquantitative system for predicting the

  2. Behavior of the unsteady jet of a mixture of a pressurized gas and dispersed particles discharged from a circular duct into the atmosphere

    Microsoft Academic Search

    D. V. Sadin

    1999-01-01

    The unsteady axisymmetric jet produced by discharge of a mixture of a pressurized gas and dispersed particles from a circular\\u000a duct into the atmosphere is studied within the framework of two-velocity, two-temperature gas dynamics. An attempt is undertaken\\u000a to allow for the effective pressure due to random particle motion. The collision mechanism is found to be essential to radial\\u000a expansion

  3. Kinetics of chlorination of zirconia in mixture with petroleum coke by chlorine gas

    NASA Astrophysics Data System (ADS)

    Jena, P. K.; Brocchi, E. A.; Reis, M. L. Dos

    1999-06-01

    Studies on the kinetics of carbothermic chlorination of zirconium dioxide in gaseous chlorine were carried out with petroleum coke fines in powder form. The amounts of ZrO2 chlorinated were found to be directly proportional to the time of chlorination in the temperature range studied (973 to 1273 K). The activation energy values for chlorination of ZrO2, in mixture with petroleum coke, was found to be 18.3 kJ/mole. The influence of particle size of petroleum coke on the chlorination of ZrO2 (-38 + 25 µm) was studied, and it was found that the rate of chlorination increased up to the size range of -75 to +53 µm, and the size finer than this produced negligible increase. The amount of petroleum coke in the mixture above 17.41 pct in excess of the stoichiometry resulted in very little increase in the rate. The effect of the partial pressure of chlorine ( pCl2) on the rate of chlorination was found to obey the following relationship, derived from the Langmuir adsorption isotherm: v = {k \\cdot K \\cdot pCl_2 }/{l + K \\cdot pCl_2 } where v is the amount of ZrO2 (g/min) reacted, k is the rate constant, and K is the equilibrium constant for adsorption of two chlorine atoms (obtained from the dissociation of a molecule of Cl2 at the carbon surface) on the surface of ZrO2. By plotting 1/ v vs 1/ pCl2, a straight-line relationship with an intercept in x-axis is obtained, further supporting the preceding equation. The dissociation of the adsorbed complex, Cl … ZrO2 … Cl to ZrCl2 and O2 is suggested to be the rate-controlling step. Subsequently, the less stable ZrCl2 combines with Cl2 to form ZrCl4 and the oxygen combines with C to form CO and CO2.

  4. Determination of the average ionization and thermodynamic regimes of xenon plasmas with an application to the characterization of blast waves launched in xenon clusters

    NASA Astrophysics Data System (ADS)

    Rodriguez, R.; Gil, J. M.; Florido, R.; Rubiano, J. G.; Mendoza, M. A.; Martel, P.; Minguez, E.; Symes, D. R.; Hohenberger, M.; Smith, R. A.

    2011-06-01

    Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon gas is commonly used for the medium in which the radiative shock propagates. In this work the average ionization and the thermodynamic regimes of xenon plasmas are determined as functions of the matter density and temperature in a wide range of plasma conditions. The results obtained will be applied to characterize blast waves launched in xenon clusters.

  5. Abatement of SO2-NOx binary gas mixtures using a ferruginous active absorbent: Part I. Synergistic effects and mechanism.

    PubMed

    Han, Yinghui; Li, Xiaolei; Fan, Maohong; Russell, Armistead G; Zhao, Yi; Cao, Chunmei; Zhang, Ning; Jiang, Genshan

    2015-04-01

    A novel ferruginous active absorbent, prepared by fly ash, industrial lime and the additive Fe(VI), was introduced for synchronous abatement of binary mixtures of SO2-NOx from simulated coal-fired flue gas. The synergistic action of various factors on the absorption of SO2 and NOx was investigated. The results show that a strong synergistic effect exists between Fe(VI) dose and reaction temperature for the desulfurization. It was observed that in the denitration process, the synergy of Fe(VI) dose and Ca/(S+N) had the most significant impact on the removal of NO, followed by the synergy of Fe(VI) and reaction temperature, and then the synergy of reaction temperature and flue gas humidity. A scanning electron microscope (SEM) and an accessory X-ray energy spectrometer (EDS) were used to observe the surface characteristics of the raw and spent absorbent as well as fly ash. A reaction mechanism was proposed based on chemical analysis of sulfur and nitrogen species concentrations in the spent absorbent. The Gibbs free energy, equilibrium constants and partial pressures of the SO2-NOx binary system were determined by thermodynamics. PMID:25872709

  6. Kinetics and mechanism of the desulfurization of liquid blast furnace slags by Ar-H2O gas mixtures

    NASA Astrophysics Data System (ADS)

    Agrawal, B.; Yurek, G. J.; Elliott, J. F.

    1983-06-01

    The rate of evolution of sulfur-bearing gases from liquid silicate slags at 1400 ‡C when exposed to Ar-H2O gas mixtures has been studied. The rate was first order with respect both to the concentration of sulfur ions adsorbed on the surface of the slag and to the partial pressure of water vapor when PH 2O was greater than 0.15 atm. When the partial pressure of water vapor was less than 0.15 atm, the rate was second order with respect to the concentration of sulfur ions adsorbed on the surface early in the reaction. At longer times in the latter case, the rate was independent of the partial pressure of water vapor, but first order with respect to the concentration of sulfur ions adsorbed on the surface. It was concluded, based on the kinetics of desulfurization, that the sulfur-bearing species evolved from the surface of the slag was S2 when the rate was second order with respect to the concentration of adsorbed sulfur ions, but SO2 was evolved when the rate was first order with respect to the concentration of adsorbed sulfur ions. Under the conditions employed in the experiments, H2S never evolved from the surface of the slag, although it did form, in some instances, in the gas phase.

  7. Thermal analysis of magnesium reactions with nitrogen/oxygen gas mixtures.

    PubMed

    Chunmiao, Yuan; Lifu, Yu; Chang, Li; Gang, Li; Shengjun, Zhong

    2013-09-15

    The thermal behavior and kinetic parameters of magnesium powder subjected to a nitrogen-rich atmosphere was investigated in thermogravimetric (TG) and differential scanning calorimeter (DSC) experiments with oxygen/nitrogen mixtures heated at rates of 5, 10, 15, and 20 °C/min. At higher temperature increase rates, the observed oxidation or nitridation steps shifted toward higher temperatures. The comparison of mass gain and heat of reaction in different nitrogen concentrations is helpful in interpreting the inerting effect of nitrogen on magnesium powder explosion in closed vessels. Activation energies for oxidation in air calculated by the Kissinger-Akahira-Sunose (KAS) method are generally consistent with previously published reports, but the method was not successful for the entire nitridation process. The change of activation energy with temperature was related to protective properties of the corresponding coating layer at particle surfaces. Two main coating layer growth processes were found in magnesium oxidation and nitridation using a modified Dreizin method which was also employed to determine activation energy for both magnesium oxidation and nitridation. For magnesium powder oxidation, activation energy calculated by the Dreizin method was close to that by KAS. Variation in activation energies was a function of different mechanisms inherent in the two methods. PMID:23846120

  8. Torsional rheometer for granular materials slurries and gas-solid mixtures and related methods

    DOEpatents

    Rajagopal, Chandrika (Allison Park, PA); Rajagopal, Kumbakonam R. (Allison Park, PA); Yalamanchili, Rattaya C. (Allison Park, PA)

    1997-01-01

    A torsional rheometer apparatus for determining rheological properties of a specimen is provided. A stationary plate and a rotatable plate are in generally coaxial position and structured to receive a specimen therebetween. In one embodiment, at least one of the plates and preferably both have roughened specimen engaging surfaces to serve to reduce undesired slippage between the plate and the specimen. A motor is provided to rotate the rotatable plate and a transducer for monitoring forces applied to the stationary plate and generating output signals to a computer which determines the desired rheological properties are provided. In one embodiment, the roughened surfaces consist of projections extending toward the specimen. Where granular material is being evaluated, it is preferred that the roughness of the plate is generally equal to the average size of the granular material being processed. In another embodiment, an air-solid mixture is processed and the roughened portions are pore openings in the plates. Air flows through the region between the two pore containing plates to maintain the solid materials in suspension. In yet another embodiment, the base of the stationary plate is provided with a deformable capacitance sensor and associated electronic means.

  9. PdO\\/Pd system equilibrium phase diagram under a gas mixture of oxygen and nitrogen

    Microsoft Academic Search

    Heng Zhang; Jack Gromek; Gayath W. Fernando; Harris L. Marcus; Sam Boorse

    2002-01-01

    The thermal equilibrium decomposition properties of the PdO-Pd system under oxygen partial pressures ranging from 0.1 to 1.0\\u000a atm in a total combined pressure of oxygen and nitrogen of 1.0 atm were investigated by means of thermal-gravimetric analyses.\\u000a The phase diagram of Pd-PdO over the range of oxygen\\/nitrogen gas concentration was established. The decomposition temperature\\u000a of PdO to Pd was

  10. A Loschmidt cell combined with holographic interferometry for binary diffusion experiments in gas mixtures including first measurements on the argon-neon system

    Microsoft Academic Search

    D. Buttig; E. Vogel; E. Bich; E. Hassel

    2011-01-01

    A new variant of the Loschmidt technique has been developed for measuring binary diffusion coefficients in gas mixtures in a temperature range from 10 to 80 °C and for pressures between 0.1 and 1 MPa. The two half cells of the thermostatted diffusion cell have a rectangular cross section and are fixed one upon the other. They can be connected

  11. The interaction potential and the determination of some cross sections and spectra of pure O2 and O2Ar gas mixtures

    Microsoft Academic Search

    U. Mingelgrina; Roy G. Gordon

    1979-01-01

    The line shapes for microwave absorption and dispersion, depolarized Raman spectrum and the sound absorption of oxygen gas were calculated. The EPR spectrum and rotational relaxation cross sections were determined. The microwave spectrum of O2-Ar mixtures and the low pressure Raman spectrum of O2-Ar were also calculated for a range of densities at 298° K and 283° K. Good agreement

  12. NATURE OF UNRESOLVED COMPLEX MIXTURE IN SIZE-DISTRIBUTED EMISSIONS FROM RESIDENTIAL WOOD COMBUSTION AS MEASURED BY THERMAL DESORPTION-GAS CHROMATOGRAPHY-MASS SPECTROMETRY

    EPA Science Inventory

    In this study, the unresolved complex mixture (UCM) in size resolved fine aerosol emissions from residential wood combustion (RWC) is examined. The aerosols are sorted by size in an electrical low-pressure impactor (ELPI) and subsequently analyzed by thermal desorbtion/gas chroma...

  13. Magnetization transfer from laser-polarized xenon to protons located in the hydrophobic cavity of the wheat nonspecific lipid transfer protein.

    PubMed

    Landon, C; Berthault, P; Vovelle, F; Desvaux, H

    2001-04-01

    Nonspecific lipid transfer protein from wheat is studied by liquid-state NMR in the presence of xenon. The gas-protein interaction is indicated by the dependence of the protein proton chemical shifts on the xenon pressure and formally confirmed by the first observation of magnetization transfer from laser-polarized xenon to the protein protons. Twenty-six heteronuclear nOes have allowed the characterization of four interaction sites inside the wheat ns-LTP cavity. Their locations are in agreement with the variations of the chemical shifts under xenon pressure and with solvation simulations. The richness of the information obtained by the noble gas with a nuclear polarization multiplied by approximately 12,000 makes this approach based on dipolar cross-relaxation with laser-polarized xenon promising for probing protein hydrophobic pockets at ambient pressure. PMID:11274467

  14. Emission spectroscopy of a microhollow cathode discharge plasma in helium-water gas mixtures

    SciTech Connect

    Namba, S.; Yamasaki, T.; Hane, Y.; Fukuhara, D.; Kozue, K.; Takiyama, K. [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527 (Japan)

    2011-10-01

    A dc microhollow cathode discharge (MHCD) plasma was generated inflowing helium gas containing water vapor. The cathode hole diameters were 0.3, 0.7, 1.0, and 2.0 mm, each with a length of 2.0 mm. Emission spectroscopy was carried out to investigate the discharge mode and to determine the plasma parameters. For the 0.3-mm cathode, stable MHCDs in an abnormal glow mode existed at pressures up to 100 kPa, whereas for larger diameters, a plasma was not generated at atmospheric pressure. An analysis of the lineshapes relevant to He at 667.8 nm and to H{alpha} at 656.3 nm implied an electron density and gas temperature of 2 x 10{sup 14} cm{sup -3} and 1100 K, respectively, for a 100-kPa discharge in the negative glow region. The dependence of the OH band, and H{alpha} intensities on the discharge current exhibited different behaviors. Specifically, the OH spectrum had a maximum intensity at a certain current, while the H atom intensity kept increasing with the discharge current. This observation implies that a high concentration of OH radicals results in quenching, leading to the production of H atoms via the reaction OH + e{sup -}{yields} O + H + e{sup -}.

  15. Pure xenon hexafluoride prepared for thermal properties studies

    NASA Technical Reports Server (NTRS)

    Malm, J. G.; Osborne, D. W.; Schreiner, F.

    1967-01-01

    Preparation of a xenon hexafluoride and sodium fluoride salt yields a sample of the highest possible purity for use in thermal measurements. The desired hexafluoride can easily be freed from the common contaminants, xenon tetra-fluoride, xenon difluoride, and xenon oxide tetrafluoride, because none of these compounds reacts with sodium fluoride.

  16. Reactive quenching of two-photon excited xenon atoms by Cl/sub 2/. [Xenon chloride laser

    SciTech Connect

    Bruce, M.R.; Layne, W.B.; Meyer, E.; Keto, J.W.

    1987-01-01

    Total binary and tertiary quench rates have been measured for the reaction Xe (5p/sup 5/6p) + Cl/sub 2/ at thermal temperatures. Xenon atoms are excited by state-selective, two-photon absorption with a uv laser. The time dependent fluorescence from the excited atom in the IR and from XeCl* (B) product near 308 nm have been measured with subnanosecond time resolution. The decay rates are measured as a function of Cl/sub 2/ pressure to 20 Torr and Xe pressure to 400 Torr. The measured reaction rates (k/sub 2/ approx. 10/sup -9/ cm/sup 3/sec/sup -1/) are consistent with a harpoon model described in a separate paper. We also measure large termolecular reaction rates for collisions with xenon atoms (k/sub 3/ approx. 10/sup -28/ cm/sup 6/sec/sup -1/). Total product fluorescence has been examined using a gated optical multichannel analyzer. We measure unit branching fractions for high vibrational levels of XeCl* (B) with very little C state fluorescence observed. The measured termolecular rates suggest similar processes will dominate at the high buffer-gas pressures used in XeCl lasers. The effect of these large reactive cross sections for neutral xenon atoms on models of the XeCl laser will be discussed.

  17. Far-ultraviolet signatures of the 3He(n,tp) reaction in noble gas mixtures

    E-print Network

    Hughes, Patrick P; Thompson, Alan K; Vest, Robert E; Clark, Charles W

    2010-01-01

    Previous work showed that the 3He(n,tp) reaction in a cell of 3He at atmospheric pressure generated tens of far-ultraviolet photons per reacted neutron. Here we report amplification of that signal by factors of 1000 and more when noble gases are added to the cell. Calibrated filter-detector measurements show that this large signal is due to noble-gas excimer emissions, and that the nuclear reaction energy is converted to far-ultraviolet radiation with efficiencies of up to 30%. The results have been placed on an absolute scale through calibrations at the NIST SURF III synchrotron. They suggest possibilities for high-efficiency neutron detectors as an alternative to existing proportional counters.

  18. Evaluation of hydrogen and ammonia gas mixtures with the suspended- gate field-effect transistor sensor array

    SciTech Connect

    Domansky, K.; Li, H.S.; Josowicz, M.; Janata, J.

    1995-12-01

    Generation of hydrogen represents a severe industrial hazard primarily because the mixture of hydrogen with air in the ratio 4.0--74.2 vol % is explosive. In some industrial applications, such as waste remediation, hydrogen, as a product of radiolysis and corrosion, occurs in the presence of ammonia, nitrous oxide, water vapor and other molecules. A low cost, reliable method for monitoring these gaseous mixtures is essential. Palladium-based layers have been used successfully as hydrogen sensitive layers in several potentiometric sensors for many years. Since the sensing mechanism is based on the catalytic decomposition of hydrogen molecules, other hydrogen-bearing gases can also produce a response. From this viewpoint, using an array of sensing elements with catalytic and noncatalytic chemically selective layers in these applications can be highly effective. Moreover, integration of this array on a single chip can be routinely achieved. The Suspended Gate Field-Effect Transistor (SGFET) is microfabricated in silicon. The metal gate of the transistor is separated from the substrate by an air gap. The chemically sensitive layer is electrodeposited on the bottom of the suspended gate. Chemical species can penetrate into the gate area and interact with the sensing layer. This interaction modulates the work function of the layer. The change in the work function results in the shift of the transistor threshold voltage. The measured threshold voltage shift is a function of the gas concentration in the sensor vicinity. By passing a small current through the suspended gate, it is possible to control the operating temperature of the sensing layer (up to 200{degrees}C) and, therefore, to modulate the sensor sensitivity, selectivity, response and recovery times. Due to the very low thermal mass, the heat is localized on the gate so that many devices can be operated on a single chip, each with the gate at different temperature.

  19. Probing the hydrophobic cavity of lipid transfer protein from Nicotiana tabacum through xenon-based NMR spectroscopy.

    PubMed

    Dubois, Lionel; Da Silva, Pedro; Landon, Céline; Huber, J Gaspard; Ponchet, Michel; Vovelle, Françoise; Berthault, Patrick; Desvaux, Hervé

    2004-12-01

    The hydrophobic cavity of Lipid Transfer Protein 1 from Nicotiana tabacum is investigated in detail by NMR using xenon as a spy. The analysis of the (129)Xe chemical shifts and self-relaxation times gives evidence of protein-xenon interaction. Thermodynamics of the binding is characterized through the study of aliphatic (1)H and (13)C chemical shift variation as a function of xenon pressure. The binding constant is evaluated to 75.5 +/- 1.0 M(-1) at 293 K. The location of xenon inside the cavity is deduced from SPINOE experiments. The noble gas appears to occupy four sites, and xenon self-relaxation experiments indicate that it quickly jumps between different sites. The chemical shifts of amide protons and nitrogens also depend on the xenon concentration, either specifically or nonspecifically for atoms at the external surface of the protein. Yet, contrary to aliphatic atoms, they do not correspond to short-range interactions as confirmed by magnetization transfer experiments between laser-polarized xenon and protons in H(2)O. These (15)N chemical shift variations, used in combination with (15)N transverse self-relaxation rates to determine the lower limit of the binding rate, consequently reveal subtle changes in the structure of the protein upon binding. PMID:15571396

  20. Enzyme recovery during gas/liquid two-phase flow microfiltration of enzyme/yeast mixtures.

    PubMed

    Mercier-Bonin, Muriel; Fonade, Christian

    2002-12-20

    The effect of a gas/liquid two-phase flow on the recovery of an enzyme was evaluated and compared with standard crossflow operation when confronted with the microfiltration of a high-fouling yeast suspension. Ceramic tubular and flat sheet membranes were used. At constant feed concentration (permeate recycling) and transmembrane pressure, the results obtained with the tubular membrane were dependent on the two-phase flow pattern. In comparison with single-phase flow performances at the same liquid velocity, the enzyme transmission was maintained at a high level with a bubble flow pattern but it decreased by 70% with a slug flow, whatever the flow rate ratio. Identical results were obtained with flat sheet membranes: for the highest flow rate ratio, the enzyme transmission was reduced by 70% even though the permeate flux was improved by 240%. During diafiltration experiments with the tubular membrane, it was found that a bubble flow pattern led to a 13% higher enzyme recovery compared to single-phase flow conditions, whereas with a slug flow the enzyme recovery was strongly reduced. With bubble flow conditions, energy consumption was minimal, confirming that this flow pattern was the most suitable for enzyme recovery. PMID:12378602

  1. Discrete model of gas-free spin combustion of a powder mixture.

    PubMed

    Klimenok, Kirill L; Rashkovskiy, Sergey A

    2015-01-01

    We propose a discrete model of gas-free combustion of a cylindrical sample which reproduces in detail a spin combustion mode. It is shown that a spin combustion, in its classical sense as a continuous spiral motion of heat release zones on the surface of the sample, does not exist. Such a concept has arisen due to the misinterpretation of the experimental data. This study shows that in fact a spinlike combustion is realized, at which two energy release zones appear on the lateral surface of the sample and propagate circumferentially in the opposite directions. After some time two new heat release zones are formed on the next layer of the cylinder surface and make the same counter-circular motion. This process continues periodically and from a certain angle it looks like a spiral movement of the luminous zone along the lateral surface of the sample. The model shows that on approaching the combustion limit the process becomes more complicated and the spinlike combustion mode shifts to a more complex mode with multiple zones of heat release moving in different directions along the lateral surface. It is shown that the spin combustion mode appears due to asymmetry of initial conditions and always transforms into a layer-by-layer combustion mode with time. PMID:25679655

  2. Separation of vapour and gas mixtures using a thin zeolite MFI membrane

    SciTech Connect

    Vroon, Z.A.E.P.; Gilde, M.J.; Kiezer, K. [Univ. of Twente, Enschede (Netherlands)] [and others

    1994-12-31

    Zeolite MFI composite membranes were prepared by in situ crystallisation. A very thin (L < 5 {mu}m) polycrystalline MFI layer was grown on a flat {alpha}-Al{sub 2}O{sub 3} support (pore radii 80 nm). XRD and SEM showed that the layer was built of small MFI particles ({+-}200 nm). The single gas flux of methane, n-butane and iso-butane are respectively 9.7, 2.7 and 0.032 10{sup -3} mol.m{sup -2}.s{sup -1} at 25{degrees}C and 100 kPa. The separation of n-butane/methane is reversible. At 25{degrees}C it is possible to separate n-butane from methane. At 200{degrees}C it is possible to separate methane from n-butane. The separation factor for 50 n-butane/50 iso-butane is 26 at 50{degrees}C. Experiments with large molecules showed that the zeolite MFI membrane contains no pores larger than inherent to the zeolite.

  3. Discrete model of gas-free spin combustion of a powder mixture

    NASA Astrophysics Data System (ADS)

    Klimenok, Kirill L.; Rashkovskiy, Sergey A.

    2015-01-01

    We propose a discrete model of gas-free combustion of a cylindrical sample which reproduces in detail a spin combustion mode. It is shown that a spin combustion, in its classical sense as a continuous spiral motion of heat release zones on the surface of the sample, does not exist. Such a concept has arisen due to the misinterpretation of the experimental data. This study shows that in fact a spinlike combustion is realized, at which two energy release zones appear on the lateral surface of the sample and propagate circumferentially in the opposite directions. After some time two new heat release zones are formed on the next layer of the cylinder surface and make the same counter-circular motion. This process continues periodically and from a certain angle it looks like a spiral movement of the luminous zone along the lateral surface of the sample. The model shows that on approaching the combustion limit the process becomes more complicated and the spinlike combustion mode shifts to a more complex mode with multiple zones of heat release moving in different directions along the lateral surface. It is shown that the spin combustion mode appears due to asymmetry of initial conditions and always transforms into a layer-by-layer combustion mode with time.

  4. Improved algorithm for quantitative analyses of infrared spectra of multicomponent gas mixtures with unknown compositions.

    PubMed

    Gianella, Michele; Sigrist, Markus W

    2009-03-01

    We present a major improvement of an algorithm based on a spectral library search for the quantitative analysis of multicomponent gas samples with unknown compositions. A quantitative spectral database of infrared spectra is used as a training set to compute regression coefficients. Concentrations are computed in the principal component space via principal component regression (PCR). In addition to previous algorithms, we introduce a rating for each candidate substance depending on the concentration found with PCR and a filter that removes candidates that are predicted with negative concentrations if their rating is below a certain threshold. Negative concentrations arise when the measured spectrum contains components that are not contained in the database. The PCR is recomputed until all candidates have a rating above the threshold. Then an adaptive filter "subtracts" the substance with the highest rating from both the measured spectrum and the library and appends it to a hit list. The iteration of this procedure directly produces a list of substances in order of descending importance (i.e., contribution to the measured absorbance) with their corresponding concentrations. The algorithm is tested on spectra of multicomponent surgical smoke samples. The four main components (water, methane, ethane, and ethene) are identified correctly (within the top 5 of the hit list) for an appropriate choice of the rating threshold. The algorithm describes the composition of the smoke sample correctly despite the presence of features in the spectrum that cannot be explained by the spectrum of any single substance present in the database. PMID:19281650

  5. Accurate gamma and MeV-electron track reconstruction with an ultra-low diffusion Xenon/TMA TPC at 10 atmospheres

    E-print Network

    Gonzalez-Diaz, Diego; Borges, F I G; Camargo, M; Carcel, S; Cebrian, S; Cervera, A; Conde, C A N; Dafni, T; Diaz, J; Esteve, R; Fernandes, L M P; Ferrario, P; Ferreira, A L; Freitas, E D C; Gehman, V M; Goldschmidt, A; Gomez-Cadenas, J J; Gutierrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Irastorza, I G; Labarga, L; Laing, A; Liubarsky, I; Lopez-March, N; Lorca, D; Losada, M; Luzon, G; Mari, A; Martin-Albo, J; Martinez-Lema, G; Martinez, A; Miller, T; Monrabal, F; Monserrate, M; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Munoz; Nebot-Guinot, M; Nygren, D; Oliveira, C A B; Perez, J; Aparicio, J L Perez; Querol, M; Renner, J; Ripoll, L; Rodriguez, J; Santos, F P; Santos, J M F dos; Serra, L; Shuman, D; Simon, A; Sofka, C; Sorel, M; Toledo, J F; Torrent, J; Tsamalaidze, Z; Veloso, J F C A; Villar, J A; Webb, R; White, J T; Yahlali, N; Azevedo, C; Aznar, F; Calvet, D; Castel, J; Ferrer-Ribas, E; Garcia, J A; Giomataris, I; Gomez, H; Iguaz, F J; Lagraba, A; Coguie, A Le; Mols, J P; Sahin,  O; Rodriguez, A; Ruiz-Choliz, E; Segui, L; Tomas, A; Veenhof, R

    2015-01-01

    We report the performance of a 10 atm Xenon/trimethylamine time projection chamber (TPC) for the detection of X-rays (30 keV) and gamma-rays (0.511-1.275 MeV) in conjunction with the accurate tracking of the associated electrons. When operated at such a high pressure and in 1%-admixtures, trimethylamine (TMA) endows Xenon with an extremely low electron diffusion (1.3 +-0.13 mm-sigma (longitudinal), 0.8 +-0.15 mm-sigma (transverse) along 1 m drift) besides forming a convenient Penning-Fluorescent mixture. The TPC, that houses 1.1 kg of gas in its active volume, operated continuously for 100 live-days in charge amplification mode. The readout was performed through the recently introduced microbulk Micromegas technology and the AFTER chip, providing a 3D voxelization of 8mm x 8mm x 1.2mm for approximately 10 cm/MeV-long electron tracks. This work was developed as part of the R&D program of the NEXT collaboration for future detector upgrades in the search of the 0bbnu decay in 136Xe, specifically those based ...

  6. Greenhouse gas production in mixtures of soil with composted and noncomposted biochars is governed by char-associated organic compounds.

    PubMed

    Borchard, Nils; Spokas, Kurt; Prost, Katharina; Siemens, Jan

    2014-05-01

    Biochar application to soil has the potential to increase soil productivity while reducing anthropogenic greenhouse gas (GHG) emissions to the atmosphere. However, techniques for conditioning this material for maximizing its effects as a soil amendment require elucidation. We examined changes of organic matter associated with two biochars after 175 d of composting and the resulting effects on GHG emissions during a 150-d incubation period. Composting decreased the amount of organic compounds that could be thermally released from the biochars and affected their molecular nature. These thermally desorbable organic compounds from initial biochars likely stimulated the oxidation of CH and inhibited the production of NO in soil-biochar mixtures. However, these reductions of GHG emissions disappeared together with thermally desorbable organic compounds after the composting of chars. Instead, addition of composted gasification coke and charcoal stimulated the formation of CH and increased NO emissions by 45 to 56%. Nitrous oxide emissions equaled 20% of the total amount of N added with composted biochars, suggesting that organic compounds and N sorbed by the chars during composting fueled GHG production. The transient nature of the suppression of CH and NO production challenges the long-term GHG mitigation potential of biochar in soil. PMID:25602826

  7. Understanding the amorphous-to-microcrystalline silicon transition in SiF4/H2/Ar gas mixtures.

    PubMed

    Dornstetter, Jean-Christophe; Bruneau, Bastien; Bulkin, Pavel; Johnson, Erik V; Roca i Cabarrocas, Pere

    2014-06-21

    We report on the growth of microcrystalline silicon films from the dissociation of SiF4/H2/Ar gas mixtures. For this growth chemistry, the formation of HF molecules provides a clear signature of the amorphous to microcrystalline growth transition. Depositing films from silicon tetrafluoride requires the removal of F produced by SiF4 dissociation, and this removal is promoted by the addition of H2 which strongly reacts with F to form HF molecules. At low H2 flow rates, the films grow amorphous as all the available hydrogen is consumed to form HF. Above a critical flow rate, corresponding to the full removal of F, microcrystalline films are produced as there is an excess of atomic hydrogen in the plasma. A simple yet accurate phenomenological model is proposed to explain the SiF4/H2 plasma chemistry in accordance with experimental data. This model provides some rules of thumb to achieve high deposition rates for microcrystalline silicon, namely, that increased RF power must be balanced by an increased H2 flow rate. PMID:24952559

  8. Reduction mechanism of high-chromium vanadium-titanium magnetite pellets by H2-CO-CO2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Tang, Jue; Chu, Man-sheng; Li, Feng; Tang, Ya-ting; Liu, Zheng-gen; Xue, Xiang-xin

    2015-06-01

    The reduction of high-chromium vanadium-titanium magnetite as a typical titanomagnetite containing 0.95wt% V2O5 and 0.61wt% Cr2O3 by H2-CO-CO2 gas mixtures was investigated from 1223 to 1373 K. Both the reduction degree and reduction rate increase with increasing temperature and increasing hydrogen content. At a temperature of 1373 K, an H2/CO ratio of 5/2 by volume, and a reduction time of 40 min, the degree of reduction reaches 95%. The phase transformation during reduction is hypothesized to proceed as follows: Fe2O3 ? Fe3O4 ? FeO ? Fe; Fe9TiO15 + Fe2Ti3O9 ? Fe2.75Ti0.25O4 ? FeTiO3 ? TiO2; (Cr0.15V0.85)2O3 ? Fe2VO4; and Cr1.3Fe0.7O3 ? FeCr2O4. The reduction is controlled by the mixed internal diffusion and interfacial reaction at the initial stage; however, the interfacial reaction is dominant. As the reduction proceeds, the internal diffusion becomes the controlling step.

  9. Measurement of Xenon Viscosity as a Function of Low Temperature and Pressure

    NASA Technical Reports Server (NTRS)

    Grisnik, Stanley P.

    1998-01-01

    The measurement of xenon gas viscosity at low temperatures (175-298 K) and low pressures (350 torr-760 torr) has been performed in support of Hall Thruster testing at NASA Lewis Research Center. The measurements were taken using the capillary flow technique. Viscosity measurements were repeatable to within 3%. The results in this paper are in agreement with data from Hanley and Childs and suggest that the data from Clarke and Smith is approximately 2% low. There are no noticeable pressure effects on xenon absolute viscosity for the pressure range from 350 torr to 760 torr.

  10. Cryogenic xenon droplets for advanced lithography

    SciTech Connect

    Gouge, M.J.; Fisher, P.W.

    1996-04-01

    A cryogenic xenon droplet production system for use in anadvanced laser plasma source for x-ray lithography has been designed, fabricated, and tested at ORNL. The droplet generator is based on proven (ink jet printer) drop-on-demand.

  11. A new developed velocity of sound measurement device for characterization of multi-component gas mixtures under elevated temperatures and pressures.

    PubMed

    Seibel, C; Suedmeyer, J; Fieback, T M

    2014-07-01

    Inline process control by measurement of velocity of sound of fluids is a direct and comprehensive technique [J. D. N. Cheeke and Z. Wang, "Acoustic wave gas sensors," Sens. Actuators B 59, 146-153 (1999); J. W. Grate, S. J. Martin, and R. M. White, "Acoustic wave microsensors," Anal. Chem. 65, 1868 (1993)]. Depending on the varying conditions of measuring fluid(s), temperatures and pressures, it is a challenging task to find the best possible acoustic setup. Taking this background into account, a velocity of sound measurement device for temperatures up to 475 K and pressures up to 24 MPa was designed and assembled that is to be used for testing different resonator types. Two bulk acoustic wave resonators out of the commonly used lead zirconatetitanate compound (PZT) were tested at different test fluids under temperatures up to 423.15 K and pressures up to 24 MPa [S. Gebhardt, L. Seffner, F. Schlenkirch, and A. Schönecker, "PZT thick films for sensor and actuator applications," J. Eur. Ceram. Soc. 27, 4177-4180 (2007)]. Initially the pure gases methane, ethane, carbon dioxide, nitrogen, and helium were measured, followed by multi-component gas mixtures. Beside methane-based binary and ternary gas mixtures, a quaternary gas mixture comprising methane, ethane, carbon dioxide, and helium was analyzed. Results for all measurement fluids in a broad temperature and pressure range show a relative deviation to theoretical values derived from GERG-2008 smaller than 0.5%. PMID:25085164

  12. Coupled gas flow/solid dynamics model for predicting the formation of fracture patterns in gas well simulation experiments. [Propellant mixture used instead of explosives to fracture rock surrounding borehole

    SciTech Connect

    Taylor, L.M.; Swenson, D.V.; Cooper, P.W.

    1984-07-01

    A two-dimensional finite element model for predicting fracture patterns obtained in high energy gas fracture experiments is presented. In these experiments, a mixture of propellants is used instead of explosives to fracture the rock surrounding the borehole. The propellant mixture is chosen to tailor the pressure pulse so that multiple fractures emanate from the borehole. The model allows the fracture pattern and pressure pulse to be calculated for different combinations of propellant mixture, in situ stress conditions, and rock properties. The model calculates the amount of gas generated by the burning propellants using a burn rate given by a power law in pressure. By assuming that the gas behaves as a perfect gas and that the flow down the fractures is isothermal, the loss of gas from the borehole due to flow down the cracks is accounted for. The flow of gas down the cracks is included in an approximate manner by assuming self-similar pressure profiles along the fractures. Numerical examples are presented and compared to three different full-scale experiments. Results show a good correlation with the experimental data over a wide variety of test parameters. 9 reference, 10 figures, 3 tables.

  13. Kinetic boundary layers in gas mixtures: Systems described by nonlinearly coupled kinetic and hydrodynamic equations and applications to droplet condensation and evaporation

    SciTech Connect

    Widder, M.E.; Titulaer, U.M. (Johannes-Kepler-Universitaet Linz (Austria))

    1993-03-01

    The authors consider a mixture of heavy vapor molecules and a light carrier gas surrounding a liquid droplet. The vapor is described by a variant of the Klein-Kramers equation; the gas is described by the Navier-Stokes equations; the droplet acts as a heat source due to the released heat of condensation. The exchange of momentum and energy between the constituents of the mixture is taken into account by force terms in the kinetic equation and source terms in the Navier-Stokes equations. These are chosen to obtain maximal agreement with the irreversible thermodynamics of a gas mixture. The structure of the kinetic boundary layer around the sphere is determined from the self-consistent solution of this set of coupled equations with appropriate boundary conditions at the surface of the sphere. The kinetic equation is rewritten as a set of coupled moment equations. A complete set of solutions of these moment equations is constructed by numerical integration inward from the region far away from the droplet, where the background inhomogeneities are small. A technique developed earlier is used to deal with the numerical instability of the moment equations. The solutions obtained for given temperature and pressure profiles in the gas are then combined linearly such that they obey the boundary conditions at the droplet surface; from this solution source terms for the Navier-Stokes equation of the gas are constructed and used to determine improved temperature and pressure profiles for the background gas. For not too large temperature differneces between the droplet and the gas at infinity, self-consistency is reached after a few iterations. The method is applied to the condensation of droplets from a supersaturated vapor as well as to strong evaporation of droplets under the influence of an external heat source, where corrections of up to 40% are obtained.

  14. Transportable Xenon Laboratory (TXL-1) Operations Manual

    SciTech Connect

    Thompson, Robert C.; Stewart, Timothy L.; Willett, Jesse A.; Woods, Vincent T.

    2011-03-07

    The Transportable Xenon Laboratory Operations Manual is a guide to set up and shut down TXL, a fully contained laboratory made up of instruments to identify and measure concentrations of the radioactive isotopes of xenon by taking air samples and analyzing them. The TXL is housed in a standard-sized shipping container. TXL can be shipped to and function in any country in the world.

  15. Ventilator-driven xenon ventilation studies

    SciTech Connect

    Chilcoat, R.T.; Thomas, F.D.; Gerson, J.I.

    1984-07-01

    A modification of a common commercial Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilatory rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and positive end-expiratory pressure (PEEP) are provided if needed. The system can be converted quickly for conventional studies with spontaneous respiration.

  16. Ventilator-driven xenon ventilation studies

    SciTech Connect

    Chilcoat, R.T.; Thomas, F.D.; Gerson, J.I.

    1984-07-01

    A modification of a common commerical Xe-133 ventilation device is described for mechanically assisted ventilation imaging. The patient's standard ventilator serves as the power source controlling the ventilator rate and volume during the xenon study, but the gases in the two systems are not intermixed. This avoids contamination of the ventilator with radioactive xenon. Supplemental oxygen and positive end-expiratory pressure (PEEP) are provided if needed. The system can be converted quickly for conventional studies with spontaneous respiration.

  17. Design of Solid Form Xenon-124 Target for Producing I-123 Radioisotope Using Computer Simulation Techniques

    SciTech Connect

    Kamali Moghaddam, K.; Sadeghi, M. [Nuclear Research Center for Agriculture and Medicine - NRCAM, AEOI, P.O. Box 31585-4395, Karaj (Iran, Islamic Republic of); Kakavand, T.; Shokri Bonab, S. [Zanjan University, Zanjan (Iran, Islamic Republic of)

    2006-07-01

    Recently in Cyclotron and Nuclear Medicine Department of NRCAM, at Atomic Energy organization of Iran (AEOI), a system for producing 1-123 via Xe-124 gas target technology, has been constructed and installed. One of the major problems in this system is the highly expensive cost of the enriched Xenon-124 gas. Therefore, saving this gas inside the system is very important. Unfortunately, by accidental rupture of the window foil or bad function of O-rings, the whole Xenon gas will escape from the system immediately. In this paper, by using computer codes; ALICE91, SRIM and doing some calculations we are going to demonstrate our latest effort for feasibility study of producing I-123 with the above mentioned reactions, but using Xe-124 solid target instead. According to our suggested design, a conical shaped irradiation vessel made of copper with 1 mm thickness, 1 cm outlet diameter, 5 cm length and 12 deg. angle at summit can be fixed inside a liquid nitrogen housing chamber. The Xenon-124 gas will be sent to the inside of this very cold conical trap and eventually deposited on its surface in solid form. Our calculation shows that during bombardment with 17-28 MeV proton energy, the thickness of solidified Xenon layer will remain around .28 mm. Likewise; thermo-dynamical calculation shows that in order to prevent the evaporation of solidified Xenon, the maximum permissible proton beam current for this system should be less than 1.4 {mu}A. According to these working conditions, the production yield of I-123 can be predicted to be around 150 mCi/{mu}Ah. (authors)

  18. Stirring Up an Elastic Fluid: Critical Viscosity of Xenon-2 (CVX-2)

    NASA Technical Reports Server (NTRS)

    Berg, Robert F.; Moldover, Michael R.; Zimmerli, Gregory A.; Motil, Susan M. (Technical Monitor)

    2002-01-01

    Whipped cream stays in place even when turned upside down. Yet it readily flows through the nozzle of a spray can to reach the dessert plate. This demonstrates the phenomenon of shear thinning that is important to many industrial and physical processes. Paints, film emulsions, and other complex solutions that are highly viscous under normal conditions but become thin and flow easily under shear forces. A simple fluid, such as water, does not exhibit shear thinning under normal conditions. Very close to the liquid-vapor critical point, where the distinction between liquid and vapor disappears, the fluid becomes more complex and is predicted to display shear thinning. At the critical point, xenon atoms interact over long distances in a classical model of cooperative phenomena. Physicists rely on this system to learn how long-range order arises. The Critical Viscosity of Xenon Experiment (CVX-2) will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Although it does not easily combine with other chemicals, its viscosity at the critical point can be used as a model for a range of fluids. Viscosity originates from the interactions of individual molecules. It is so complicated that, except for the simplest gas, it cannot be calculated accurately from theory. Tests with critical fluids can provide key data, but are limited on Earth because critical fluids are highly compressed by gravity. CVX-2 employs a tiny metal screen vibrating between two electrodes in a bath of critical xenon. The vibrations and how they dampen are used to measure viscosity. CVX flew on STS-85 (1997), where it revealed that, close to the critical point, the xenon is partly elastic: it can 'stretch' as well as flow. For STS-107, the hardware has been enhanced to determine if critical xenon is a shear-thinning fluid.

  19. Abiotic synthesis of high-molecular-weight organics from an inorganic gas mixture of carbon monoxide, ammonia, and water by 3 MeV proton irradiation

    NASA Astrophysics Data System (ADS)

    Takano, Yoshinori; Ohashi, Akihiro; Kaneko, Takeo; Kobayashi, Kensei

    2004-02-01

    The abiotic formation of high-molecular-weight organics from an inorganic gas mixture of carbon monoxide, ammonia, and water as a result of 3 MeV proton irradiation from a Van de Graaff accelerator was experimentally verified. The inorganic gas mixture was simulated for representative of interstellar medium. The irradiation products included amino acid (AA) precursors, and the molecular weight distribution ranged from several hundred to a maximum of 3000 Da. Both proteinous and nonproteinous AAs were detected after acid hydrolysis. Thus, the primary irradiation products were not free AA analogs, but were AA precursors having high molecular weight. The present results have significant implications regarding the extraterrestrial origins of AA precursors, such as meteoritic organic compounds and the organic composition of interstellar dust particles.

  20. Reactor simulations of the GEC reference cell reactor with an ICP source for Ar/Cl2 and BCl3/Cl2 gas mixtures.

    NASA Astrophysics Data System (ADS)

    Veerasingam, Ramana; Choi, Seung J.; Riley, Merle; Hoekstra, Robert; Kushner, Mark

    1996-10-01

    The ICP (inductively coupled plasma) device is a widely researched plasma etching technology to meet the stringent requirements of dielectric and metal etch for the next generation semiconductor wafers. At Sandia, the GEC reference cell has been modified to include a planar coil geometry to couple the RF power to the plasma inductively. Measurements of densities of electrons, CL-, Ar+, and recently of ion current flux have been made. In this paper, we will present results of simulations modeling the GEC cell for Ar/CL2 and BCL3/Cl2 gas mixtures using the HPEM and GEMINI code packages. Results will be parametrized with power, pressure, and gas mixture. In addition, simulations of the ion current flux using a sheath model developed at Sandia and the HPEM will be performed and compared to data.

  1. XENON dark matter searches: Results and the future

    NASA Astrophysics Data System (ADS)

    Brown, Andrew; Xenon Collaboration

    2014-06-01

    XENON100 is a dark matter search experiment looking for elastic WIMP scattering using a 62 kg liquid target. WIMP search data from XENON100 published in 2012 has set the world's strongest limits on WIMP-nucleus spinindependent, elastic scattering. It has also set the strongest limits on WIMP-nucleus spin-dependent scattering considering neutron scattering only, and competitive limits considering proton scattering only. The successor experiment to XENON100, XENON1T, is currently under construction, with commissioning scheduled to begin in 2014. XENON1T's design goal is a 100 fold increase in sensitivity for elastic WIMP searches over XENON100.

  2. High altitude chemically reacting gas particle mixtures. Volume 1: A theoretical analysis and development of the numerical solution. [rocket nozzle and orbital plume flow fields

    NASA Technical Reports Server (NTRS)

    Smith, S. D.

    1984-01-01

    The overall contractual effort and the theory and numerical solution for the Reacting and Multi-Phase (RAMP2) computer code are described. The code can be used to model the dominant phenomena which affect the prediction of liquid and solid rocket nozzle and orbital plume flow fields. Fundamental equations for steady flow of reacting gas-particle mixtures, method of characteristics, mesh point construction, and numerical integration of the conservation equations are considered herein.

  3. Experimental aspects of combined NO x and SO 2 removal from flue-gas mixture in an integrated wet scrubber-electrochemical cell system

    Microsoft Academic Search

    K. Chandrasekara Pillai; Sang Joon Chung; T. Raju; Il-Shik Moon

    2009-01-01

    The objective of this work was to study the effect of some operating conditions on the simultaneous removal of NOx and SO2 from simulated NO–SO2–air flue-gas mixtures in a scrubber column. The gaseous components were absorbed into 6M HNO3 electrolyte in the scrubber in a counter-current mode, and were oxidatively removed by the Ag(II) mediator oxidant electrochemically generated in an

  4. Direct measurement of the electron density in electron-beam-irradiated Ar-F2 gas mixtures by time-resolved interferometry

    Microsoft Academic Search

    Z. Rozenberg; M. Rokni

    1987-01-01

    The electron density has been measured in electron-beam irradiated Ar-F2 gas mixtures for the first time, using time-resolved infrared interferometry, and the attachment-rate constant for fluorine at zero electric field is determined for the first time. The results show a dramatic dependence of the attachment-rate constant on fluorine concentration and on the e-beam current density. It is shown that this

  5. Quantum scattering theory of relaxation phenomena. Coupled states calculations of rotational relaxation and spectral line shapes in HeH2 gas mixtures

    Microsoft Academic Search

    Rudolf Goldflam; Donald J. Kouri

    1977-01-01

    The recently developed coupled states theory of relaxation phenomena of Goldflam and Kouri is tested against the close coupling results of Shafer and Gordon for the He-H2 gas mixture. Predictions of pressure broadening (line widths and shifts) and NMR spin-lattice relaxation cross sections are shown to agree extremely well with the close coupling results, in contrast to the previous expectations

  6. The effects of breathing a helium–oxygen gas mixture on maximal pulmonary ventilation and maximal oxygen consumption during exercise in acute moderate hypobaric hypoxia

    Microsoft Academic Search

    Takeshi Ogawa; Jose A. L. Calbet; Yasushi Honda; Naoto Fujii; Takeshi Nishiyasu

    2010-01-01

    To test the hypothesis that maximal exercise pulmonary ventilation ($$ \\\\dot{V}{\\\\text{E}}_{ \\\\max } $$) is a limiting factor affecting maximal oxygen uptake ($$ \\\\dot{V}{\\\\text{O}}_{{ 2 {\\\\text{max}}}} $$) in moderate hypobaric hypoxia (H), we examined the effect of breathing a helium–oxygen gas mixture (He–O2; 20.9% O2), which would reduce air density and would be expected to increase $$ \\\\dot{V}{\\\\text{E}}_{ \\\\max }

  7. Ultralow-power nonlinear optics using tapered optical fibers in metastable xenon

    E-print Network

    T. B. Pittman; D. E. Jones; J. D. Franson

    2013-08-26

    We demonstrate nanowatt-level saturated absorption using a sub-wavelength diameter tapered optical fiber (TOF) suspended in a gas of metastable xenon atoms. This ultralow-power nonlinearity is enabled by a small optical mode area propagating over a relatively long distance through the Xe gas. The use of inert noble gasses in these kinds of TOF experiments may offer practical advantages over the use of reactive alkali vapors such as rubidium.

  8. Ultralow-power nonlinear optics using tapered optical fibers in metastable xenon

    E-print Network

    Pittman, T B; Franson, J D

    2013-01-01

    We demonstrate nanowatt-level saturated absorption using a sub-wavelength diameter tapered optical fiber (TOF) suspended in a gas of metastable xenon atoms. This ultralow-power nonlinearity is enabled by a small optical mode area propagating over a relatively long distance through the Xe gas. The use of inert noble gasses in these kinds of TOF experiments may offer practical advantages over the use of reactive alkali vapors such as rubidium.

  9. Effect of N{sub 2} + H{sub 2} gas mixtures in plasma nitriding on tribological properties of duplex surface treated steels

    SciTech Connect

    Taktak, Sukru [Afyon Kocatepe University, Technical Education Faculty, Department of Metal Education, Afyonkarahisar (Turkey)], E-mail: taktak@aku.edu.tr; Gunes, Ibrahim; Ulker, Sukru; Yalcin, Yilmaz [Afyon Kocatepe University, Technical Education Faculty, Department of Metal Education, Afyonkarahisar (Turkey)

    2008-12-15

    Thermo-reactive diffusion chromizing followed by pulsed plasma nitriding were carried out on AISI 52100 and 8620 bearing steels. The chromized samples were pulse-plasma nitrided for 5 h at 500 deg. C in various N{sub 2}-H{sub 2} gas mixtures. The coated steels were characterized using scanning electron microscopy, X-ray diffraction and microhardness testing. The unlubricated wear behaviors of only chromized and duplex treated steels were investigated in ball-on-disc system tests at room temperature. X-ray diffraction patterns of the duplex treated samples containing H{sub 2} indicated the formation of dominant CrN and Cr{sub 2}N nitrides as well as the formation of Cr{sub 3}C{sub 2} and Cr{sub 7}C{sub 3} carbides. Gas mixtures in the plasma nitriding, which was performed after chromizing, have a significant influence on the wear rate of the duplex treated steels. The wear and friction tests showed that the lowest friction coefficient and wear rates were observed for the samples duplex treated in a 50%N{sub 2} +50%H{sub 2} plasma. Conversely, the lowest wear resistance was observed on the samples duplex treated in a gas mixture of 75%N{sub 2} + 25%H{sub 2}, probably due to formation of a hard and brittle layer.

  10. Evaluation of the permeability of formaldehyde and water through a permeation tube for the preparation of an accurate formaldehyde reference gas mixture.

    PubMed

    Aoki, Nobuyuki; Kato, Kenji; Aoyagi, Reiji; Wakayama, Masahiko

    2013-11-21

    A system for continuous generation and analysis of formaldehyde (HCHO) in a nitrogen gas mixture prepared using a permeation method was fabricated in order to evaluate the permeability of HCHO and water (H2O) through a permeation tube. Specifically, the mass balance of HCHO and H2O through a permeation tube was evaluated using the system. The results indicated that the mass loss in the permeation tube accounted for the amount of HCHO and H2O measured using a spectrometer. The permeability of HCHO was calculated by subtracting the mass loss of H2O from the permeation tube per unit of time as determined from the mass balance results. The calculated permeability of HCHO was 75.7 ± 3.4 mg min(-1) (k = 2) for the HCHO gas mixture prepared by the permeation method using a permeation tube filled with paraformaldehyde that was vacuum-dried at 95 °C. The calculated permeability agreed with the permeability obtained using the dinitrophenylhydrazine-derivatization method (72.7 ± 4.4 mg min(-1) (k = 2)) within the level of uncertainty. This technique, in which the mass loss of H2O from the permeation tube is subtracted, can therefore provide a reference gas mixture with an accurate HCHO concentration using the permeation method. PMID:24080643

  11. Deposition and characterization of organic polymer thin films using a dielectric barrier discharge with different C2Hm/N2 (m = 2, 4, 6) gas mixtures

    NASA Astrophysics Data System (ADS)

    Chandrashekaraiah, Thejaswini Halethimmanahally; Bogdanowicz, Robert; Danilov, Vladimir; Schäfer, Jan; Meichsner, Jürgen; Hippler, Rainer

    2015-06-01

    Organic polymer thin films have been deposited on Si(100) and aluminum coated glass substrates by a dielectric barrier discharge (DBD) operated at medium pressure using different C2H m /N2 ( m = 2, 4, 6) gas mixtures. The deposited films were characterized by various spectroscopic techniques. Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS) revealed the chemical functional groups present in the films. The surface chemical compositions have been derived from X-ray photo electron spectroscopy (XPS). FT-IRRAS and XPS show the presence of sp, s p 2 and s p 3 bonds of carbon and nitrogen. Various functional groups such as NH containing, saturated and unsaturated alkyl groups have been identified. Thin films obtained from C2H2/N2 and C2H4/N2 gas mixtures revealed a higher N/C ratio when compared to thin films obtained from C2H6/N2. Thickness, refractive index and extinction coefficient were evaluated by spectroscopic ellipsometry (SE). Significant differences between the films obtained with different gas mixtures are observed.

  12. Deposition and characterization of organic polymer thin films using a dielectric barrier discharge with different C2Hm/N2 (m = 2, 4, 6) gas mixtures

    NASA Astrophysics Data System (ADS)

    Halethimmanahally Chandrashekaraiah, Thejaswini; Bogdanowicz, Robert; Danilov, Vladimir; Schäfer, Jan; Meichsner, Jürgen; Hippler, Rainer

    2015-06-01

    Organic polymer thin films have been deposited on Si(100) and aluminum coated glass substrates by a dielectric barrier discharge (DBD) operated at medium pressure using different C2Hm/N2 (m = 2, 4, 6) gas mixtures. The deposited films were characterized by various spectroscopic techniques. Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS) revealed the chemical functional groups present in the films. The surface chemical compositions have been derived from X-ray photo electron spectroscopy (XPS). FT-IRRAS and XPS show the presence of sp, sp2 and sp3 bonds of carbon and nitrogen. Various functional groups such as NH containing, saturated and unsaturated alkyl groups have been identified. Thin films obtained from C2H2/N2 and C2H4/N2 gas mixtures revealed a higher N/C ratio when compared to thin films obtained from C2H6/N2. Thickness, refractive index and extinction coefficient were evaluated by spectroscopic ellipsometry (SE). Significant differences between the films obtained with different gas mixtures are observed.

  13. Cooling molten salt reactors using “gas-lift”

    SciTech Connect

    Zitek, Pavel, E-mail: zitek@kke.zcu.cz, E-mail: klimko@kke.zcu.cz; Valenta, Vaclav, E-mail: zitek@kke.zcu.cz, E-mail: klimko@kke.zcu.cz; Klimko, Marek, E-mail: zitek@kke.zcu.cz, E-mail: klimko@kke.zcu.cz [University of West Bohemia in Pilsen, Univerzitní 8, 306 14 Pilsen (Czech Republic)

    2014-08-06

    This study briefly describes the selection of a type of two-phase flow, suitable for intensifying the natural flow of nuclear reactors with liquid fuel - cooling mixture molten salts and the description of a “Two-phase flow demonstrator” (TFD) used for experimental study of the “gas-lift” system and its influence on the support of natural convection. The measuring device and the application of the TDF device is described. The work serves as a model system for “gas-lift” (replacing the classic pump in the primary circuit) for high temperature MSR planned for hydrogen production. An experimental facility was proposed on the basis of which is currently being built an experimental loop containing the generator, separator bubbles and necessary accessories. This loop will model the removal of gaseous fission products and tritium. The cleaning of the fuel mixture of fluoride salts eliminates problems from Xenon poisoning in classical reactors.

  14. NWA 8114: Analysis of Xenon in this Unique Martian Meteorite

    NASA Astrophysics Data System (ADS)

    Crowther, S. A.; Jastrzebski, N. D.; Nottingham, M.; Theis, K. J.; Gilmour, J. D.

    2014-09-01

    The Xe composition of NWA 8114 is dominated by martian atmospheric xenon, with contributions from terrestrial atmospheric contamination at low temperature and fissiogenic xenon at high temperature. The overall systematics are similar to Nakhla.

  15. Adsorption of xenon on vicinal copper and platinum surfaces

    Microsoft Academic Search

    Layton Baker

    2008-01-01

    The adsorption of xenon was studied on Cu(111), Cu(221), Cu(643) and on Pt(111), Pt(221), and Pt(531) using low energy electron diffraction (LEED), temperature programmed desorption (TPD) of xenon, and ultraviolet photoemission of adsorbed xenon (PAX). These experiments were performed to study the atomic and electronic structure of stepped and step-kinked, chiral metal surfaces. Xenon TPD and PAX were performed on

  16. Xenon behavior in TiN: A coupled XAS/TEM study

    NASA Astrophysics Data System (ADS)

    Bès, R.; Gaillard, C.; Millard-Pinard, N.; Gavarini, S.; Martin, P.; Cardinal, S.; Esnouf, C.; Malchère, A.; Perrat-Mabilon, A.

    2013-03-01

    Titanium nitride is a refractory material that is being considered as an inert matrix in future Generation IV nuclear reactors, in particular in relation to the Gas-cooled Fast Reactor. The main role of this matrix would be to act as a barrier against the release of fission products, in particular gaseous ones like xenon. This release phenomenon will be enhanced by high temperatures expected in the fuel vicinity: 1200 °C under normal conditions, and up to 1800 °C under accidental conditions. It is therefore necessary to investigate the behavior of volatile fission products in TiN under high temperature and irradiation. Indeed, these basic data are very useful to predict the volatile fission products released under these extreme conditions. Our previous work has shown that Xe introduced by ion implantation in sintered TiN tends to be released as a result of annealing, due to a transport mechanism towards the sample surface. The aim of the present work is to determine under which physical state Xe is in TiN. Xenon was first introduced using ion implantation at 800 keV in TiN samples obtained by hot pressing at several concentrations ranging from 0.4 to 8 at.%. Secondly, samples were annealed at high temperature, from 1000 °C to 1500 °C. Xe was then characterized by X-ray Absorption Spectroscopy and Transmission Electron Microscopy. The formation of intragranular xenon bubbles was demonstrated, and the xenon concentration which is sufficient to form bubbles is found to be lower than 0.4 at.% under our experimental conditions. These bubbles were found unpressurised at 15 K. Their size increases with the temperature and the local xenon concentration. For the highest xenon concentrations, a mechanism involving the formation of a Xe interconnected bubble network is proposed to explain Xe massive release observed by Rutherford Backscattering Spectrometry experiments.

  17. Dendrite engineering on xenon crystals.

    PubMed

    Fell, Marco; Bilgram, Jörg

    2007-06-01

    The experimental work presented focuses on transient growth, morphological transitions, and control of xenon dendrites. Dendritic free growth is perturbed by two different mechanisms: Shaking and heating up to the melting temperature. Spontaneous and metastable multitip configurations are stabilized, coarsening is reduced, leading to a denser sidebranch growth, and a periodic tip splitting is found during perturbation by shaking. On the other hand, heating leads to controlled sidebranching and characteristic transitions of the tip shape. A deterministic behavior is found besides the random-noise-driven growth. The existence of a limit cycle is supported by the findings. Together the two perturbation mechanisms allow a "dendrite engineering"--i.e., a reproducible controlling of the crystal shape during its growth. The tip splitting for dendritic free growth is found not to be a splitting of the tip in two; rather, the respective growth velocities of the main tip and the fins change. The latter then surpass the main tip and develop into new tips. The occurrence of three- and four-tip configurations is explained with this mechanism. Finite-element calculations of the heat flow and the convective flow in the growth vessel show that the idea of a single axisymmetric toroidal convection roll across the whole growth vessel has to be dropped. The main effect of convection under Earth's gravity is the compression of the diffusive temperature field around the downward-growing tip. A model to explain the symmetry of dendritic crystals--e.g., snow crystals--is developed, based on the interaction of crystal shape and heat flow in the crystal. PMID:17677269

  18. Reflectance of polytetrafluoroethylene for xenon scintillation light

    NASA Astrophysics Data System (ADS)

    Silva, C.; Pinto da Cunha, J.; Pereira, A.; Chepel, V.; Lopes, M. I.; Solovov, V.; Neves, F.

    2010-03-01

    Gaseous and liquid xenon particle detectors are being used in a number of applications including dark matter search and neutrino-less double beta decay experiments. Polytetrafluoroethylene (PTFE) is often used in these detectors both as electrical insulator and as a light reflector to improve the efficiency of detection of scintillation photons. However, xenon emits in the vacuum ultraviolet (VUV) wavelength region (? ?175 nm) where the reflecting properties of PTFE are not sufficiently known. In this work, we report on measurements of PTFE reflectance, including its angular distribution, for the xenon scintillation light. Various samples of PTFE, manufactured by different processes (extruded, expanded, skived, and pressed) have been studied. The data were interpreted with a physical model comprising both specular and diffuse reflections. The reflectance obtained for these samples ranges from about 47% to 66% for VUV light. Other fluoropolymers, namely, ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), and perfluoro-alkoxyalkane (PFA) were also measured.

  19. Reflectance of polytetrafluoroethylene for xenon scintillation light

    SciTech Connect

    Silva, C.; Pinto da Cunha, J.; Pereira, A.; Chepel, V.; Lopes, M. I.; Solovov, V.; Neves, F. [Department of Physics, LIP-Coimbra, University of Coimbra, P-3004 516 Coimbra (Portugal)

    2010-03-15

    Gaseous and liquid xenon particle detectors are being used in a number of applications including dark matter search and neutrino-less double beta decay experiments. Polytetrafluoroethylene (PTFE) is often used in these detectors both as electrical insulator and as a light reflector to improve the efficiency of detection of scintillation photons. However, xenon emits in the vacuum ultraviolet (VUV) wavelength region ({lambda}{approx_equal}175 nm) where the reflecting properties of PTFE are not sufficiently known. In this work, we report on measurements of PTFE reflectance, including its angular distribution, for the xenon scintillation light. Various samples of PTFE, manufactured by different processes (extruded, expanded, skived, and pressed) have been studied. The data were interpreted with a physical model comprising both specular and diffuse reflections. The reflectance obtained for these samples ranges from about 47% to 66% for VUV light. Other fluoropolymers, namely, ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), and perfluoro-alkoxyalkane (PFA) were also measured.

  20. Properties of excited xenon atoms in a plasma display panel

    Microsoft Academic Search

    Han S. Uhm; Byoung H. Hong; Phil Y. Oh; Eun H. Choi

    2009-01-01

    The luminance efficiency of a plasma display panel is directly related to the vacuum ultraviolet (VUV) light that is emitted from excited xenon (Xe) atoms and molecules. It is therefore necessary to investigate the properties of excited xenon atoms. This study presents experimental data associated with the behavior of excited xenon atoms in a PDP discharge cell and compares the

  1. A POWER CALIBRATION METHOD USING THE XENON POISONING

    Microsoft Academic Search

    M. Damy de Souza Santos; P. Saraiva de Toledo

    1959-01-01

    A method of power calibration using the reactivity variation due to ; xenon poisoning is developed. Two cases are considered: reactivity variation ; after reacting the xenon equillbrium poisoning; time variation of reactiviyy due ; to the non-equilibrium xenon poisoning. Both methods are applicable in the high ; flux region. In the second method some care must be taken in

  2. 78 FR 41768 - Chemical Substances and Mixtures Used in Oil and Gas Exploration or Production; TSCA Section 21...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-11

    ...industry is a large industry involving a range of...operations and classes of chemical substances and mixtures...information with respect to chemical substances (Ref. 1) including chemical substances used in the E&P industry. Before...

  3. Effects of tropical high tannin non legume and low tannin legume browse mixtures on fermentation parameters and methanogenesis using gas production technique.

    PubMed

    Seresinhe, T; Madushika, S A C; Seresinhe, Y; Lal, P K; Orskov, E R

    2012-10-01

    In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it's highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental substitution of legume forage increased gas production parameters, NH3-N, IVDMD and microbial population in the fermentation liquid. Methane production was not significantly affected by the presence of CT or different levels of CP in forage mixtures. Among non legumes, Ceiba perntandra and Artocarpus heterophyllus performed better in mixture with L. leucocephala and G. sepium. PMID:25049496

  4. Development and calibration of field-effect transistor-based sensor array for measurement of hydrogen and ammonia gas mixtures in humid air.

    PubMed

    Domanský, K; Baldwin, D L; Grate, J W; Hall, T B; Li, J; Josowicz, M; Janata, J

    1998-02-01

    A sensor array for analyzing hydrogen and ammonia gas mixtures in humid air has been developed, built into a rugged system, and calibrated for laboratory testing. The sensor array is comprised of four chemically sensitive field-effect transistors (CHEMFETs). Chemically sensitive layers for the sensors were developed and tested using a Kelvin probe. A combination of catalytic and noncatalytic thin layers (palladium and polyaniline) was selected for the four-sensor array. The work function responses of the CHEMFET sensor array to mixtures of hydrogen, ammonia, and humid air were measured. Chemometric multivariate methods, linear and nonlinear partial least squares, were used for the calibration of the sensor array using gas mixtures in the concentration range from 0 to 10?000 ppm hydrogen and ammonia in humid air. The sensor array for ammonia showed good sensitivity, selectivity, response time, and stability and is recommended for field deployment. In contrast, the sensor array for hydrogen, though highly sensitive to hydrogen, demonstrated inadequate stability, requiring further development before deployment is recommended. PMID:21644746

  5. Phase Diagram Calculation of Gas Mixtures for Refrigeration; Reflection & Transmission Coefficients and the Effective Mass: Superconducting Proximity IV Measurements

    Microsoft Academic Search

    Gideon Friedmann

    1996-01-01

    The efficiency of Joule-Thomson refrigerators greatly improves with the addition of hydrocarbons to nitrogen as coolant, and is highly dependent on the mixture composition. To optimize it, we calculated the mixture phase diagram using the Peng-Robinson equation of state. A program was developed to solve numerically a set of coupled non-linear equations for the equilibrium of the vapor and liquid

  6. Results from the XENON100 Experiment

    NASA Astrophysics Data System (ADS)

    Melgarejo, Antonio; Xenon Collaboration

    2015-04-01

    The XENON100 detector, located at the LNGS Laboratory in Italy, has been taking dark matter data between 2008 and 2014, producing some of the best limits in the field thanks to its low background and large sensitive volume. In this talk we present the results from the last science run of the detector and the preliminary results from the combined exposure of all the science data, as well as the status of the ongoing analyses with these data. We gratefully acknowledge continued support for the XENON Dark Matter program from the National Science Foundation.

  7. Vacuum ultraviolet radiometry of xenon positive column discharges

    NASA Astrophysics Data System (ADS)

    Doughty, D. A.; Fobare, D. F.

    1995-10-01

    In order to judge the potential fluorescent lamp applications of various low-pressure positive column discharges it is necessary to measure the absolute power emitted in the ultraviolet region of the spectrum. For rare-gas discharges the principle emission occurs in the vacuum ultraviolet so that it is difficult to measure the radiant emittance (power per unit area) of the resonance radiation by standard methods. Two independent techniques are discussed for measuring the radiant emittance of positive column discharges in the vacuum ultraviolet. These techniques are used to study xenon positive column discharges at the resonance wavelength of 147 nm. The first method relies on the measurement of the resonance level density by absorption techniques. The effective decay rate of the resonance level is then determined by the simulation of resonance radiation transport. These two quantities are combined to yield the radiant emittance at 147 nm without implementing vacuum ultraviolet techniques. The second method uses a measurement of the resonance radiation normal to the positive column axis made with a calibrated vacuum ultraviolet detector. The angular distribution of the resonance radiation leaving the tube is determined by the simulation of resonance radiation transport. The detector measurement places the angular distribution of the radiance on an absolute scale, which can then be integrated to yield the radiant emittance. These two techniques are compared for pure xenon discharges at various pressures and currents.

  8. Lifetime Modeling of Xenon Hollow Cathodes Used in Electric Propulsion

    NASA Astrophysics Data System (ADS)

    Kovaleski, Scott

    2001-10-01

    Xenon hollow cathodes with barium calcium aluminate impregnated tungsten inserts are widely used in electric propulsion. These high current, low power cathodes are employed in ion thrusters, Hall thrusters, and on the International Space Station in plasma contactors. The entitlement lifetime of a thermionic emission cathode impregnated with barium-containing compounds is determined by the evolution and transport of barium away from the emitter surface. A model is being developed to study the process of barium transport and loss from the emitter insert in hollow cathodes. A thermodynamic model of the chemical process of barium evolution has been adapted from that of Lipeles and Kan^1. The model accounts for the diffusion of barium and barium oxide gas through the xenon expellant and loss of barium-containing gases through the cathode orifice as well as loss by condensation. Axial barium density profiles are presented and cathode lifetimes are estimated. Results of the model are compared with experimental results from the extensive hollow cathode life test database at the NASA Glenn Research Center. 1. Lipeles, R.A., Kan, H.K.A., Appl. Surf. Sci. 16, 189(1983).

  9. Sedimentation of a two-dimensional colloidal mixture exhibiting liquid-liquid and gas-liquid phase separation: a dynamical density functional theory study.

    PubMed

    Malijevský, Alexandr; Archer, Andrew J

    2013-10-14

    We present dynamical density functional theory results for the time evolution of the density distribution of a sedimenting model two-dimensional binary mixture of colloids. The interplay between the bulk phase behaviour of the mixture, its interfacial properties at the confining walls, and the gravitational field gives rise to a rich variety of equilibrium and non-equilibrium morphologies. In the fluid state, the system exhibits both liquid-liquid and gas-liquid phase separation. As the system sediments, the phase separation significantly affects the dynamics and we explore situations where the final state is a coexistence of up to three different phases. Solving the dynamical equations in two-dimensions, we find that in certain situations the final density profiles of the two species have a symmetry that is different from that of the external potentials, which is perhaps surprising, given the statistical mechanics origin of the theory. The paper concludes with a discussion on this. PMID:24116640

  10. The final LDRD report for the project entitled: {open_quotes}Enhanced analysis of complex gas mixtures by pattern recognition of microsensor array signals{close_quotes}

    SciTech Connect

    Hughes, R.C.; Osbourn, G.C.

    1996-09-01

    Microsensors do not have the selectivity to chemical species available in large laboratory instruments. This project employed arrays of catalytically gated silicon microsensors with different catalysts to create data streams which can be analyzed by pattern recognition programs. One of the most significant accomplishments of the program was the demonstration of that mixtures of H{sub 2} with the oxidants NO{sub x} and O{sub 2} could distinguished from one another by the use of different catalytic metals on the Sandia Robust Hydrogen (SRH) sensors and the newly developed pattern recognition algorithm. This sensor system could be used to identify explosive gas mixtures and analyze exhaust streams for pollution control.

  11. Synthesis of Cryptophanes with Two Different Reaction Sites: Chemical Platforms for Xenon Biosensing.

    PubMed

    Chapellet, Laure-Lise; Cochrane, James R; Mari, Emilie; Boutin, Céline; Berthault, Patrick; Brotin, Thierry

    2015-06-19

    We report the synthesis of new water-soluble cryptophane host molecules that can be used for the preparation of (129)Xe NMR-based biosensors. We show that the cryptophane-223 skeleton can be modified to introduce a unique secondary alcohol to the propylenedioxy linker. This chemical functionality can then be exploited to introduce a functional group that is different from the six chemical groups attached to the aromatic rings. In this approach, the generation of a statistical mixture when trying to selectively functionalize a symmetrical host molecule is eliminated, which enables the efficient large-scale production of new cryptophanes that can be used as chemical platforms ready to use for the preparation of xenon biosensors. To illustrate this approach, two molecular platforms have been prepared, and the ability of these new derivatives to bind xenon has been investigated. PMID:26020365

  12. Multiwavelength discrimination and measurements of a two-gas mixture by use of a broadly tunable mid-infrared semiconductor laser.

    PubMed

    Peng, Chuan; Le Han, Q; Yang, Rui Q; Hill, Cory J

    2006-02-20

    Spectroscopic detection of gases can be achieved by measuring a few species-specific absorption lines, requiring very accurate wavelength control. Alternatively, it can be achieved by using many wavelengths spread over a wide range; each wavelength need not be optimal spectroscopically, but all collectively form a unique fingerprint for the species of interest. Statistical regression can be used to quantify their concentrations. An experimental evaluation of this concept involved using a 3.1 microm broadly tunable Sb-based mid-IR laser to discriminate and measure mixtures of acetylene and water vapor with absorption spectral overlaps. As many as 30 wavelengths from approximately 3200 to approximately 3280 cm-1 were used to measure 5 x 5 combinations of the two-gas concentration. Statistical analysis of the results validates the concept. Each gas concentration was consistently and reliably measured without any problem of interference from the other. In addition, the method was sufficiently sensitivite to detect unusual discrepancies by use of statistical analysis. Optimization of the system's detection capability and its receiver-operating characteristics is demonstrated. The results suggest that the statistical multiwavelength broadband approach to detection of gas mixture can be a highly effective alternative to species-specific single-line spectroscopy. PMID:16523793

  13. Supercontinuum laser absorption spectroscopy in the mid-infrared range for identification and concentration estimation of a multi-component atmospheric gas mixture

    NASA Astrophysics Data System (ADS)

    Cezard, Nicolas; Dobroc, Alexandre; Canat, Guillaume; Duhant, Mathieu; Renard, William; Alhenc-Gelas, Claire; Lefebvre, Sidonie; Fade, Julien

    2011-11-01

    In this paper, we first report the recent achievement of a mid-infrared supercontinuum fiber laser source in our laboratory. Using fluoride fibers, we have generated a wavelength supercontinuum covering the whole 2-3.5?m range, and delivering a power spectral density of 0.3 mW/nm on a large spectral range. Experimental results are presented. This source can open opportunities for broadband remote sensing of multiple gas species in the atmosphere, especially above 3 ?m, where numerous organic compounds have strong absorption signatures. Therefore, we consider a simple Supercontinuum Laser Absorption Spectroscopy (SLAS) experiment, and we develop a numerical case study above 3 ?m, involving a multi-component gas mixture. We first describe a method for modelling noisy spectroscopic signals. Then we consider the inverse problem, and attempt to perform identification and quantitative estimation of the gas mixture. After showing the inapplicability of a direct multi-linear regression, we focus on processing methods that use complexity penalization principles, and show that they can address efficiently the identification/estimation problem. Among various penalization criteria, those based on Minimum Description Length (MDL) approaches are shown to perform particularly well. Finally, we apply these methods to preliminary experimental spectroscopic signals obtained with supercontinuum sources in our laboratory.

  14. Solubilities of methane, nitrogen, carbon dioxide, and a natural gas mixture in aqueous sodium bicarbonate solutions under high pressure and elevated temperature

    SciTech Connect

    Gao, J.; Zheng, D.Q.; Guo, T.M. [Univ. of Petroleum, Beijing (China)] [Univ. of Petroleum, Beijing (China)

    1997-01-01

    The solubility of natural gas mixtures in formation water (brine) plays an important role in estimating the natural gas reserve, the formation/dissociation conditions of methane hydrates in situ, and the interfacial tension of the hydrocarbon-formation water system. However, solubility data at high pressure and elevated temperature conditions for aqueous electrolyte systems are rare. Recently, in the reservoirs found at the South China Sea areas, the main salt species in the formation water is sodium bicarbonate, and the solubility data of gases in aqueous sodium bicarbonate solutions under reservoir conditions have not previously been reported. An apparatus for measuring the solubility of gases in aqueous electrolyte solutions under high pressure and elevated temperature conditions is described. The solubility of methane, carbon dioxide, nitrogen, and a natural gas mixture in aqueous sodium bicarbonate solutions were measured up to 58 MPa and 403 K. The modified Patel-Teja equation of state proposed by Zuo and Guo (1991) for aqueous electrolyte systems was applied to correlate the measured solubility data, and satisfactory results were obtained.

  15. Effect of glow DBD modulation on gas and thin film chemical composition: case of Ar/SiH4/NH3 mixture

    NASA Astrophysics Data System (ADS)

    Vallade, Julien; Bazinette, Remy; Gaudy, Laura; Massines, Françoise

    2014-06-01

    In recent years, atmospheric pressure plasma-enhanced chemical vapour deposition has been identified as a convenient way to deposit good quality thin films. With this type of process, where the gas mixture is injected on one side of the electrodes, the chemical composition of the gas evolves with the gas residence time in the plasma. The consequence is a possible gradient in the chemical composition over the thickness of in-line coatings. The present work shows that the modulation of the plasma with a square signal significantly reduces this gradient while the drawback of low growth rate is avoided by increasing the discharge power. This study deals with plane/plane glow dielectric barrier discharges (DBDs) in an Ar/NH3/SiH4 gas mixture to make thin films. The 50 kHz discharge power of the glow DBD was varied by increasing voltage and modulating excitation. The impact on (i) the plasma development was observed through emission spectroscopy and (ii) the thin film coating through Fourier transform infrared measurements. It is shown that the modulation significantly decreases the time and the energy needed to achieve stable chemistry, enhances secondary chemistry and limits disturbance induced by impurities because of a slower decrease of SiH4 concentration and thus a higher ratio of SiH4/impurities, all very important points for in-line AP-PECVD development. When the growth rate is limited by diffusion, coating growth continues when the discharge is off, so long as there is a precursor gradient between the surface and the gas bulk. A higher discharge power steepens this gradient, which enhances diffusion from the bulk and thus growth rate.

  16. Material screening and selection for XENON100

    Microsoft Academic Search

    E. Aprile; K. Arisaka; F. Arneodo; A. Askin; L. Baudis; A. Behrens; K. Bokeloh; E. Brown; J. M. R. Cardoso; B. Choi; D. Cline; S. Fattori; A. D. Ferella; K. L. Giboni; A. Kish; C. W. Lam; J. Lamblin; R. F. Lang; K. E. Lim; J. A. M. Lopes; T. Marrodán Undagoitia; Y. Mei; A. J. Melgarejo Fernandez; K. Ni; U. Oberlack; S. E. A. Orrigo; E. Pantic; G. Plante; A. C. C. Ribeiro; R. Santorelli; J. M. F. dos Santos; M. Schumann; P. Shagin; A. Teymourian; D. Thers; E. Tziaferi; H. Wang; C. Weinheimer; M. Laubenstein; S. Nisi

    2011-01-01

    Results of the extensive radioactivity screening campaign to identify materials for the construction of XENON100 are reported. This dark matter search experiment is operated underground at Laboratori Nazionali del Gran Sasso (LNGS), Italy. Several ultra sensitive High Purity Germanium detectors (HPGe) have been used for gamma ray spectrometry. Mass spectrometry has been applied for a few low mass plastic samples.

  17. Study of helium:argon:ethane gas mixtures used in drift chambers for large-acceptance spectrometers in high magnetic fields. Final report

    SciTech Connect

    Hewitt, J.D.

    1990-12-07

    For today's large-acceptance spectrometers, precise knowledge of electrons in gases and magnetic fields is required for particle track reconstruction. Measurements under a variety of conditions must be performed in order to accurately model these processes with software simulations such as GARFIELD. At Brookhaven National Laboratory, a prototype drift chamber, constructed at the Continuous Electron Beam Accelerator Facility (CEBAF), incorporating a hex-cell wire pattern, was filled with helium:argon:ethane and tested in a high magnetic field and without the magnetic field. The results of these tests are compared and indicate little change in the drift velocity of this gas mixture in and out of a high magnetic field.

  18. Penile xenon (/sup 133/Xe) washout: a rapid method of screening for vasculogenic impotence

    SciTech Connect

    Nseyo, U.O.; Wilbur, H.J.; Kang, S.A.; Flesh, L.; Bennett, A.H.

    1984-01-01

    The radioactive inert gas xenon (/sup 133/Xe) is a well-established isotopic indicator used to assess vascular status in many organ systems. Xenon-133 was used to evaluate male impotence. Xenon-133 was injected subcutaneously at the level of the coronal sulcus in the detumescent state. Using the gamma camera, sequential images were obtained and computer-generated curves calculated. The clearance time for 50 per cent washout of the injected /sup 133/Xe (T1/2) was then calculated for each patient, as well as a control group. Preliminary findings indicate a correlation with such established techniques of evaluating erectile impotence as history, physical examination, penile pulse Doppler tracings, and brachial-penile blood pressure index. The xenon-133 washout study was a rapid, minimally invasive, reproducible, and cost-effective method of screening those impotent patients for vasculogenic etiology of their erectile impotence. We recommend the addition of this method to the surgeon engaged in the care of impotent males.

  19. In vitro gas production in rumen fluid of buffalo as affected by urea-calcium mixture in high-quality feed block.

    PubMed

    Cherdthong, Anusorn; Wanapat, Metha

    2014-04-01

    This study aimed to determine the effect of urea-calcium sulphate mixture (U-cas) levels in high-quality feed block (HQFB) on ruminal digestibility, fermentation and gas kinetics in rumen fluid of swamp buffalo by using in vitro techniques. The treatments were seven levels of U-cas incorporated in HQFB at 0, 3, 6, 9, 12, 15 and 18% and the experimental design was a completely randomized design. Gas production rate constants for the insoluble fraction, potential extent of gas and cumulative gas were linearly increased with increasing levels of U-cas in HQFB. The in vitro dry matter digestibility, in vitro organic matter digestibility, true digestibility and microbial mass were altered by treatments and were greatest at 18% U-cas supplementation. Concentrations of propionate were linearly increased with increasing levels of U-cas and was highest with U-cas supplementation at 18%. The NH3 -N concentration was highest when urea was added in the HQFB while NH3 -N concentration tended to be reduced with increasing level of U-cas. The findings suggest supplementation of 18% U-cas in HQFB improves kinetics of gas production, rumen fermentation, digestibility and microbial mass as well as controlling the rate of N degradation in the rumen of swamp buffalo. PMID:24506797

  20. Heterogeneous Nuclear Reactor Models for Optimal Xenon Control.

    NASA Astrophysics Data System (ADS)

    Gondal, Ishtiaq Ahmad

    Nuclear reactors are generally modeled as homogeneous mixtures of fuel, control, and other materials while in reality they are heterogeneous-homogeneous configurations comprised of fuel and control rods along with other materials. Similarly, for space-time studies of a nuclear reactor, homogeneous, usually one-group diffusion theory, models are used, and the system equations are solved by either nodal or modal expansion approximations. Study of xenon-induced problems has also been carried out using similar models and with the help of dynamic programming or classical calculus of variations or the minimum principle. In this study a thermal nuclear reactor is modeled as a two-dimensional lattice of fuel and control rods placed in an infinite-moderator in plane geometry. The two-group diffusion theory approximation is used for neutron transport. Space -time neutron balance equations are written for two groups and reduced to one space-time algebraic equation by using the two-dimensional Fourier transform. This equation is written at all fuel and control rod locations. Iodine -xenon and promethium-samarium dynamic equations are also written at fuel rod locations only. These equations are then linearized about an equilibrium point which is determined from the steady-state form of the original nonlinear system equations. After studying poisonless criticality, with and without control, and the stability of the open-loop system and after checking its controllability, a performance criterion is defined for the xenon-induced spatial flux oscillation problem in the form of a functional to be minimized. Linear -quadratic optimal control theory is then applied to solve the problem. To perform a variety of different additional useful studies, this formulation has potential for various extensions and variations; for example, different geometry of the problem, with possible extension to three dimensions, heterogeneous -homogeneous formulation to include, for example, homogeneously -distributed burnable poisons, inclusion of additional terms, for example, fast fission and resonance absorption, different fuel and control rod diameters, different distances between rods, different fuel enrichment in different fuel rods, different control concentration in different control rods, and different forms of the performance index, to name a few.