Science.gov

Sample records for xenon gas mixture

  1. 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.

  2. Fission-fragment excited xenon/rare gas mixtures. II. Small signal gain of the 2. 03 [mu]m xenon transition

    SciTech Connect

    Hebner, G.A.; Hays, G.N. )

    1993-04-15

    The results of small signal gain measurements of the 2.03 [mu]m (5[ital d][3/2][sub 1][minus]6[ital p][3/2][sub 1]) xenon transition in fission-fragment excited Ar/Xe, He/Ar/Xe, Ne/Ar/Xe, and He/Ne/Ar/Xe gas mixtures is presented. Time resolved small signal gain was probed using a cw He/Xe discharge laser as a function of total pressure, xenon concentration, pump power, He/Ne/Ar buffer ratio, and impurity concentration. Small signal gains of up to 6%/cm were observed for pump rates of 15 W/cm[sup 3]. Addition of helium and/or neon to the argon buffer increased the width of the laser gain and reduced the absorption observed under some experimental conditions. Experimentally determined gain scaling laws for several gas mixtures are presented.

  3. Fission-fragment excited xenon/rare gas mixtures. I. Laser parameters of the 1. 73 [mu]m xenon transition

    SciTech Connect

    Hebner, G.A.; Hays, G.N. )

    1993-04-15

    Laser parameters for the 1.73 [mu]m (5[ital d][3/2][sub 1][minus]6[ital p][5/2][sub 2]) xenon transition in fission-fragment excited Ar/Xe, He/Ar/Xe, Ne/Ar/Xe, and He/Ne/Ar/Xe gas mixtures are presented. Using a cw F center laser, time resolved small signal gain was probed as a function of total pressure, xenon concentration, pump power, He/Ne/Ar buffer ratio and impurity concentration. Small signal gains of up to 2%/cm were observed for pump rates of 30 W/cm[sup 3]. Addition of helium and/or neon to the argon buffer increased the width of the time resolved laser gain pulse and reduced the absorption observed under some experimental conditions. Experimentally determined gain scaling laws for several gas mixtures are presented. The measured small signal gain was coupled with the results of laser cavity measurements to calculate the saturation intensity for several gas mixtures. The addition of helium or neon increases the saturation intensity for several gas mixtures. Laser cavity measurements as well as the gain [times] saturation intensity product indicate that the 1.73 [mu]m power efficiency is approximately 2% for several gas mixtures.

  4. Description and commissioning of NEXT-MM prototype: first results from operation in a Xenon-Trimethylamine gas mixture

    NASA Astrophysics Data System (ADS)

    lvarez, V.; Aznar, F.; Borges, F. I. G. M.; Calvet, D.; Crcel, S.; Castel, J.; Cebrin, S.; Cervera, A.; Conde, C. A. N.; Dafni, T.; Dias, T. H. V. T.; Daz, J.; Druillole, F.; Egorov, M.; Esteve, R.; Evtoukhovitch, P.; Fernandes, L. M. P.; Ferrario, P.; Ferreira, A. L.; Ferrer-Ribas, E.; Freitas, E. D. C.; Gehman, V. M.; Gil, A.; Giomataris, I.; Goldschmidt, A.; Gmez, H.; Gmez-Cadenas, J. J.; Gonzlez-Daz, D.; Gutirrez, R. M.; Hauptman, J.; Hernando Morata, J. A.; Herrera, D. C.; Iguaz, F. J.; Irastorza, I. G.; Jinete, M. A.; Labarga, L.; Laing, A.; Le Coguie, A.; Liubarsky, I.; Lopes, J. A. M.; Lorca, D.; Losada, M.; Luzn, G.; Mar, A.; Martn-Albo, J.; Martnez, A.; Martnez-Lema, G.; Miller, T.; Moiseenko, A.; Mols, J. P.; Monrabal, F.; Monteiro, C. M. B.; Mora, F. J.; Moutinho, L. M.; Muoz Vidal, J.; Natal da Luz, H.; Navarro, G.; Nebot-Guinot, M.; Nygren, D.; Oliveira, C. A. B.; Palma, R.; Prez, J.; Prez Aparicio, J. L.; Renner, J.; Ripoll, L.; Rodrguez, A.; Rodrguez, J.; Santos, F. P.; dos Santos, J. M. F.; Segui, L.; Serra, L.; Shuman, D.; Simn, A.; Sofka, C.; Sorel, M.; Toledo, J. F.; Toms, A.; Torrent, J.; Tsamalaidze, Z.; Veloso, J. F. C. A.; Villar, J. A.; Webb, R. C.; White, J. T.; Yahlali, N.

    2014-03-01

    A technical description of NEXT-MM and its commissioning and first performance is reported. Having an active volume of ~ 35 cm drift 28 cm diameter, it constitutes the largest Micromegas-read TPC operated in Xenon ever constructed, made by a sectorial arrangement of the 4 largest single wafers manufactured with the Microbulk technique to date. It is equipped with a suitably pixelized readout and with a sufficiently large sensitive volume ( ~ 23 l) so as to contain long ( ~ 20 cm) electron tracks. First results obtained at 1 bar for Xenon and Trymethylamine (Xe-(2%)TMA) mixture are presented. The TPC can accurately reconstruct extended background tracks. An encouraging full-width half-maximum of 11.6 % was obtained for ~ 29 keV gammas without resorting to any data post-processing.

  5. 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.

  6. Ethane-xenon mixtures under shock conditions

    DOE PAGESBeta

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

    2015-04-22

    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. In order 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. Furthermore, themore » 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.« less

  7. Ethane-xenon mixtures under shock conditions

    SciTech Connect

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

    2015-04-22

    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. In order 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. Furthermore, 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.

  8. Ethane-xenon mixtures under shock conditions

    NASA Astrophysics Data System (ADS)

    Flicker, Dawn; Magyar, Rudolph; Root, Seth; Cochrane, Kyle; Mattsson, Thomas

    2015-06-01

    Mixtures of light and heavy elements arise in inertial confinement fusion and planetary science. We present results on the physics of molecular scale mixing through a validation study of equation of state (EOS) properties. Density functional theory molecular dynamics (DFT/QMD) at elevated-temperature and pressure is used to obtain the properties of pure xenon, ethane, and various compressed mixture compositions along their principal Hugoniots. To validate the QMD simulations, we performed high-precision shock compression experiments using Sandia's Z-Machine. A bond tracking analysis of the simulations correlates the sharp rise in the Hugoniot curve with completion of dissociation in ethane. DFT-based simulation results compare well with experimental data and are used to provide insight into the dissociation as a function of mixture composition. Interestingly, we find that the compression ratio for complete dissociation is similar for ethane, Xe-ethane, polymethyl-pentene, and polystyrene, suggesting that a limiting compression exists for C-C bonded systems. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, Security Administration under contract DE-AC04-94AL85000.

  9. Gas mixtures for X-ray proportional counters

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    Results are presented which detail the performance of proportional counters when filled with a wide variety of argon- and xenon-based gas mixtures. It is shown that alternative gas mixtures can offer considerable advantages in the counters. The mixtures of argon plus 10 percent propane and xenon plus 10 percent propylene look particularly attractive in terms of operating voltage and energy resolution. The quench gas CO2 returns the poorest results in all areas except aging.

  10. Energy transfer studies in krypton-xenon mixtures excited in a cooled DC discharge

    NASA Astrophysics Data System (ADS)

    Krylov, B.; Gerasimov, G.; Morozov, A.; Arnesen, A.; Hallin, R.; Heijkenskjold, F.

    2000-01-01

    The VUV spectrum of gaseous mixtures of krypton with a small amount of xenon added was investigated in the range 115-200 nm. The mixtures were excited in a capillary DC discharge where the capillary could be cooled by using liquid nitrogen. The mixed molecule band around the Xe I resonance line at λ = 147 nm and the mixed molecule continuum to the long wavelength side from the line were analysed. The band around λ = 147 nm was identified as transitions between a weakly bound excited state and the weakly bound ground state of XeKr molecules. When cooling the capillary wall, the appearance of the Xe2 continuum was observed. The effect is ascribed to energy transfer between molecular states as a consequence of radiation trapping in the band around λ = 147 nm. The role of the mixed molecule in the formation of the VUV spectrum of the gas mixture is discussed and underlined.

  11. Review of Helium and Xenon Pure Component and Mixture Transport Properties and Recommendation of Estimating Approach for Project Prometheus (Viscosity and Thermal Conductivity)

    NASA Astrophysics Data System (ADS)

    Haire, Melissa A.; Vargo, David D.

    2007-01-01

    The selected configuration for the Project Prometheus Space Nuclear Power Plant was a direct coupling of Brayton energy conversion loop(s) to a single reactor heat source through the gas coolant/working fluid. A mixture of helium (He) and xenon (Xe) gas was assumed as the coolant/working fluid. Helium has superior thermal conductivity while xenon is added to increase the gas atomic weight to benefit turbomachinery design. Both elements have the advantage of being non-reactive. HeXe transport properties (viscosity and thermal conductivity) were needed to calculate pressure drops and heat transfer rates. HeXe mixture data are limited, necessitating the use of semi-empirical correlations to calculate mixture properties. Several approaches are available. Pure component properties are generally required in the mixture calculations. While analytical methods are available to estimate pure component properties, adequate helium and xenon pure component data are available. This paper compares the sources of pure component data and the approaches to calculate mixture properties. Calculated mixture properties are compared to the limited mixture data and approaches are recommended to calculate both pure component and mixture properties. Given the limited quantity of HeXe mixture data (all at one atmosphere), additional testing may have been required for Project Prometheus to augment the existing data and confirm the selection of mixture property calculation methods.

  12. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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. c2002 John Wiley & Sons, Ltd.

  14. Parameters of VUV radiation from a DC capillary discharge in a mixture of krypton with xenon

    NASA Astrophysics Data System (ADS)

    Gerasimov, G. N.; Krylov, B. E.; Hallin, R.; Arnesen, A.

    2006-06-01

    This paper describes the technique and the results of measurement of the power and geometry of the VUV radiation beam from a dc capillary discharge in a mixture of krypton and xenon. The angular divergence of narrowband VUV radiation of the heteronuclear KrXe* molecule is shown to be narrower as compared to that of the discharge radiation in the range 200-1000 nm. The power of VUV radiation from a discharge tube 80 cm long is found to exceed 10 mW.

  15. Characteristics of a high pressure gas proportional counter filled with xenon

    NASA Technical Reports Server (NTRS)

    Sakurai, H.; Ramsey, B. D.

    1991-01-01

    The characteristics of a conventional cylindrical geometry proportional counter filled with high pressure xenon gas up to 10 atm. were fundamentally investigated for use as a detector in hard X-ray astronomy. With a 2 percent methane gas mixture the energy resolutions at 10 atm. were 9.8 percent and 7.3 percent for 22 keV and 60 keV X-rays, respectively. From calculations of the Townsend ionization coefficient, it is shown that proportional counters at high pressure operate at weaker reduced electric field than low pressure counters. The characteristics of a parallel grid proportional counter at low pressure showed similar pressure dependence. It is suggested that this is the fundamental reason for the degradation of resolution observed with increasing pressure.

  16. Low-pressure glow discharge in a Xenon/Chlorine mixture

    NASA Astrophysics Data System (ADS)

    Shuaibov, A. K.; Shimon, L. L.; Shevera, I. V.; Dashchenko, A. I.

    2002-12-01

    The spatial, electrical, and optical characteristics of a transverse glow discharge and a volume discharge with a spherical anode and plane cathode in low-pressure Xe/Cl2 mixtures are studied. It is shown that the transverse glow discharge in mixtures with a low chlorine content occupies most of the interelectrode gap and exists in the form of strata. As the total pressure ( P≥300 Pa) and the partial chlorine pressure ( P(Cl2)≥80 Pa) increase, a solitary plasma domain with a volume of 1-2 cm3 forms in the discharge gap. It acts as a selective source of UV radiation in the XeCl(D-X) 236-nm, Cl2 (D'-A') 257-nm, and XeCl(B-X) 308-nm bands. In certain Xe/Cl2 mixtures, plasma self-oscillations in the frequency range 1-100 kHz are observed. The current of a low-pressure volume discharge with a spherical anode and plane cathode and the emission from it have both a dc and an ac component. The pressure and composition of the working mixture, as well as the average current of the volume discharge are optimized to attain the maximum emission intensity of the XeCl(D,B-X) bands. Low-pressure volume discharges in xenon/chlorine mixtures can be used as active media in low-pressure large-aperture planar or cylindrical excimer-halogen lamps emitting modulated or repetitive pulsed UV radiation.

  17. 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.

  18. Gas mixtures for spark gap closing switches

    DOEpatents

    Christophorou, Loucas G.; McCorkle, Dennis L.; Hunter, Scott R.

    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.

  19. Cluster formation restricts dynamic nuclear polarization of xenon in solid mixtures

    PubMed Central

    Kuzma, N. N.; Pourfathi, M.; Kara, H.; Manasseh, P.; Ghosh, R. K.; Ardenkjaer-Larsen, J. H.; Kadlecek, S. J.; Rizi, R. R.

    2012-01-01

    During dynamic nuclear polarization (DNP) at 1.5 K and 5 T, 129Xe nuclear magnetic resonance (NMR) spectra of a homogeneous xenon/1-propanol/trityl-radical solid mixture exhibit a single peak, broadened by 1H neighbors. A second peak appears upon annealing for several hours at 125 K. Its characteristic width and chemical shift indicate the presence of spontaneously formed pure Xe clusters. Microwave irradiation at the appropriate frequencies can bring both peaks to either positive or negative polarization. The peculiar time evolution of 129Xe polarization in pure Xe clusters during DNP can be modelled as an interplay of spin diffusion and T1 relaxation. Our simple spherical-cluster model offers a sensitive tool to evaluate major DNP parameters in situ, revealing a severe spin-diffusion bottleneck at the cluster boundaries and a significant sample overheating due to microwave irradiation. Subsequent DNP system modifications designed to reduce the overheating resulted in four-fold increase of 129Xe polarization, from 5.3% to 21%. PMID:22979875

  20. A simple high-sensitivity technique for purity analysis of xenon gas

    NASA Astrophysics Data System (ADS)

    Leonard, D. S.; Dobi, A.; Hall, L. J. Kaufman, C.; Langford, T.; Slutsky, S.; Yen, Y.-R.

    2010-09-01

    We report on the development and performance of a high-sensitivity purity-analysis technique for gaseous xenon. The gas is sampled at macroscopic pressure from the system of interest using a UHV leak valve. The xenon present in the sample is removed with a liquid-nitrogen cold trap, and the remaining impurities are observed with a standard vacuum mass-spectroscopy device. Using calibrated samples of xenon gas spiked with known levels of impurities, we find that the minimum detectable levels of N 2, O 2, and methane are 1×10 -9, 160×10 -12, and 60 ×10 -12 g/g, respectively. This represents an improvement of about a factor of 10 000 compared to measurements performed without a cold trap.

  1. 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.

  2. Ternary gas mixture for diffuse discharge switch

    DOEpatents

    Christophorou, Loucas G. (Oak Ridge, TN); Hunter, Scott R. (Oak Ridge, TN)

    1988-01-01

    A new diffuse discharge gas switch wherein a mixture of gases is used to take advantage of desirable properties of the respective gases. There is a conducting gas, an insulating gas, and a third gas that has low ionization energy resulting in a net increase in the number of electrons available to produce a current.

  3. Dielectric gas mixtures containing sulfur hexafluoride

    DOEpatents

    Cooke, Chathan M.

    1979-01-01

    Electrically insulating gaseous media of unexpectedly high dielectric strength comprised of mixtures of two or more dielectric gases are disclosed wherein the dielectric strength of at least one gas in each mixture increases at less than a linear rate with increasing pressure and the mixture gases are present in such proportions that the sum of their electrical discharge voltages at their respective partial pressures exceeds the electrical discharge voltage of each individual gas at the same temperature and pressure as that of the mixture.

  4. An improved measurement of electron-ion recombination in high-pressure xenon gas

    NASA Astrophysics Data System (ADS)

    Serra, L.; Sorel, M.; Álvarez, V.; Borges, F. I. G.; Camargo, M.; Cárcel, S.; Cebrián, S.; Cervera, A.; Conde, C. A. N.; Dafni, T.; Díaz, J.; Esteve, R.; Fernandes, L. M. P.; Ferrario, P.; Ferreira, A. L.; Freitas, E. D. C.; Gehman, V. M.; Goldschmidt, A.; Gómez-Cadenas, J. J.; González-Díaz, D.; Gutiérrez, R. M.; Hauptman, J.; Hernando Morata, J. A.; Herrera, D. C.; Irastorza, I. G.; Labarga, L.; Laing, A.; Liubarsky, I.; Lopez-March, N.; Lorca, D.; Losada, M.; Luzón, G.; Marí, A.; Martín-Albo, J.; Martínez-Lema, G.; Martínez, A.; Miller, T.; Monrabal, F.; Monserrate, M.; Monteiro, C. M. B.; Mora, F. J.; Moutinho, L. M.; Muñoz Vidal, J.; Nebot-Guinot, M.; Nygren, D.; Oliveira, C. A. B.; Pérez, J.; Pérez Aparicio, J. L.; Querol, M.; Renner, J.; Ripoll, L.; Rodríguez, A.; Rodríguez, J.; Santos, F. P.; dos Santos, J. M. F.; Shuman, D.; Simón, A.; Sofka, C.; Toledo, J. F.; Torrent, J.; Tsamalaidze, Z.; Veloso, J. F. C. A.; Villar, J. A.; Webb, R.; White, J. T.; Yahlali, N.

    2015-03-01

    We report on results obtained with the NEXT-DEMO prototype of the NEXT-100 high-pressure xenon gas time projection chamber (TPC), filled with pure xenon gas at 10 bar pressure and exposed to an alpha decay calibration source. Compared to our previous measurements with alpha particles, an upgraded detector and improved analysis techniques have been used. We measure event-by-event correlated fluctuations between ionization and scintillation due to electron-ion recombination in the gas, with correlation coefficients between -0.80 and -0.56 depending on the drift field conditions. By combining the two signals, we obtain a 2.8% FWHM energy resolution for 5.49 MeV alpha particles and a measurement of the optical gain of the electroluminescent TPC. The improved energy resolution also allows us to measure the specific activity of the radon in the gas due to natural impurities. Finally, we measure the average ratio of excited to ionized atoms produced in the xenon gas by alpha particles to be 0.561± 0.045, translating into an average energy to produce a primary scintillation photon of Wex=(39.2± 3.2) eV.

  5. Physiological response of rats to delivery of helium and xenon: implications for hyperpolarized noble gas imaging

    NASA Technical Reports Server (NTRS)

    Ramirez, M. P.; Sigaloff, K. C.; Kubatina, L. V.; Donahue, M. A.; Venkatesh, A. K.; Albert, M. S.; ALbert, M. S. (Principal Investigator)

    2000-01-01

    The physiological effects of various hyperpolarized helium and xenon MRI-compatible breathing protocols were investigated in 17 Sprague-Dawley rats, by continuous monitoring of blood oxygen saturation, heart rate, EKG, temperature and endotracheal pressure. The protocols included alternating breaths of pure noble gas and oxygen, continuous breaths of pure noble gas, breath-holds of pure noble gas for varying durations, and helium breath-holds preceded by two helium rinses. Alternate-breath protocols up to 128 breaths caused a decrease in oxygen saturation level of less than 5% for either helium or xenon, whereas 16 continuous-breaths caused a 31.5% +/- 2.3% decrease in oxygen saturation for helium and a 30.7% +/- 1. 3% decrease for xenon. Breath-hold protocols up to 25 s did not cause the oxygen saturation to fall below 90% for either of the noble gases. Oxygen saturation values below 90% are considered pathological. At 30 s of breath-hold, the blood oxygen saturation dropped precipitously to 82% +/- 0.6% for helium, and to 76.5% +/- 7. 4% for xenon. Breath-holds longer than 10 s preceded by pre-rinses caused oxygen saturation to drop below 90%. These findings demonstrate the need for standardized noble gas inhalation procedures that have been carefully tested, and for continuous physiological monitoring to ensure the safety of the subject. We find short breath-hold and alternate-breath protocols to be safe procedures for use in hyperpolarized noble gas MRI experiments. Copyright 2000 John Wiley & Sons, Ltd.

  6. Viscosity of multicomponent partially ionized gas mixtures

    NASA Technical Reports Server (NTRS)

    Armaly, B. F.; Sutton, K.

    1980-01-01

    An approximate method is proposed for predicting the viscosity of partially ionized gas mixtures. This technique expresses the viscosity of a mixture in terms of the viscosities of the individual pure components, is simple in form, and does not require large computer run times or storage. Thus, the technique is suitable for use with complex flowfields and heat-transfer calculations. Results for gas mixtures which are representative of the atmospheres of Jupiter, Earth, and Venus, are presented and it is shown that the results compare favorably with detailed kinetic-theory analyses.

  7. Improved gas mixtures for gas-filled radiation detectors

    DOEpatents

    Christophorou, L.G.; McCorkle, D.L.; Maxey, D.V.; Carter, J.G.

    1980-03-28

    Improved binary and ternary gas mixtures for gas-filled radiation detectors are provided. The components are chosen on the basis of the principle that the first component is one molecular gas or mixture of two molecular gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a noble gas having a very small cross section at and below about 1.0 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electric field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

  8. Gas mixtures for gas-filled radiation detectors

    DOEpatents

    Christophorou, Loucas G.; McCorkle, Dennis L.; Maxey, David V.; Carter, James G.

    1982-01-05

    Improved binary and ternary gas mixtures for gas-filled radiation detectors are provided. The components are chosen on the basis of the principle that the first component is one molecular gas or mixture of two molecular gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a noble gas having a very small cross section at and below about 1.0 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electric field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

  9. Improved gas mixtures for gas-filled particle detectors

    DOEpatents

    Christophorou, L.G.; McCorkle, D.L.; Maxey, D.V.; Carter, J.G.

    Improved binary and tertiary gas mixture for gas-filled particle detectors are provided. The components are chosen on the basis of the principle that the first component is one gas or mixture of two gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a gas (Ar) having a very small cross section at and below about 0.5 eV; whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electron field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

  10. Gas mixtures for gas-filled particle detectors

    DOEpatents

    Christophorou, Loucas G.; McCorkle, Dennis L.; Maxey, David V.; Carter, James G.

    1980-01-01

    Improved binary and tertiary gas mixtures for gas-filled particle detectors are provided. The components are chosen on the basis of the principle that the first component is one gas or mixture of two gases having a large electron scattering cross section at energies of about 0.5 eV and higher, and the second component is a gas (Ar) having a very small cross section at and below aout 0.5 eV, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 eV where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of E/P (pressure-reduced electron field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient E/P ranges as compared with conventional gas mixtures.

  11. Gas mixtures for gas-filled radiation detectors

    SciTech Connect

    Carter, J.G.; Christophorou, L.G.; Maxey, D.V.; Mccorkle, D.L.

    1982-01-05

    Improved binary and ternary gas mixtures for gas-filled radiation detectors are provided. The components are chosen on the basis of the principle that the first component is one molecular gas or mixture of two molecular gases having a large electron scattering cross section at energies of about 0.5 ev and higher, and the second component is a noble gas having a very small cross section at and below about 1.0 ev, whereby fast electrons in the gaseous mixture are slowed into the energy range of about 0.5 ev where the cross section for the mixture is small and hence the electron mean free path is large. The reduction in both the cross section and the electron energy results in an increase in the drift velocity of the electrons in the gas mixtures over that for the separate components for a range of e/p (Pressure-reduced electric field) values. Several gas mixtures are provided that provide faster response in gas-filled detectors for convenient e/p ranges as compared with conventional gas mixtures.

  12. Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas

    NASA Astrophysics Data System (ADS)

    Chu, X. X.; Zhang, M. M.; Zhang, D. X.; Xu, D.; Qian, Y.; Liu, W.

    2014-01-01

    In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H2 from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H2 in helium recycle gas are less than 1 ppb.

  13. Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas

    SciTech Connect

    Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W.; Zhang, M. M.; Xu, D.

    2014-01-29

    In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

  14. Structural Plasticity of the Phage P22 Tail Needle gp26 Probed with Xenon Gas

    SciTech Connect

    Olia, A.; Casjens, S; Cingolani, G

    2009-01-01

    The tail needle, gp26, is a highly stable homo-trimeric fiber found in the tail apparatus of bacteriophage P22. In the mature virion, gp26 is responsible for plugging the DNA exit channel, and likely plays an important role in penetrating the host cell envelope. In this article, we have determined the 1.98 A resolution crystal structure of gp26 bound to xenon gas. The structure led us to identify a calcium and a chloride ion intimately bound at the interior of alpha-helical core, as well as seven small cavities occupied by xenon atoms. The two ions engage in buried polar interactions with gp26 side chains that provide specificity and register to gp26 helical core, thus enhancing its stability. Conversely, the distribution of xenon accessible cavities correlates well with the flexibility of the fiber observed in solution and in the crystal structure. We suggest that small internal cavities in gp26 between the helical core and the C-terminal tip allow for flexible swinging of the latter, without affecting the overall stability of the protein. The C-terminal tip may be important in scanning the bacterial surface in search of a cell-envelope penetration site, or for recognition of a yet unidentified receptor on the surface of the host.

  15. Skin blood flow from gas transport: helium xenon and laser Doppler compared

    SciTech Connect

    Neufeld, G.R.; Galante, S.R.; Whang, J.M.; DeVries, D.; Baumgardner, J.E.; Graves, D.J.; Quinn, J.A.

    1988-03-01

    A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics.

  16. A novel 83mKr tracer method for characterizing xenon gas and cryogenic distillation systems

    NASA Astrophysics Data System (ADS)

    Rosendahl, S.; Bokeloh, K.; Brown, E.; Cristescu, I.; Fieguth, A.; Huhmann, C.; Lebeda, O.; Levy, C.; Murra, M.; Schneider, S.; V'enos, D.; Weinheimer, C.

    2014-10-01

    The radioactive isomer 83mKr, has many properties that make it very useful for various applications. Its low energy decay products, like conversion, shake-off and Auger electrons as well as X- and γ-rays are used for calibration purposes in neutrino mass experiments and direct dark matter detection experiments. Thanks to the short half-life of 1.83 h and the decay to the ground state 83Kr, one does not risk contamination of any low-background experiment with long-lived radionuclides. In this paper, we present a new approach, using 83mKr as a radioactive tracer in noble gases. A method of doping 83mKr, into xenon gas and its detection, using special custom-made detectors, based on a photomultiplier tube, is described. Two applications of this method are presented: firstly, it can be used to characterize the particle flow inside of gas routing systems and determine the circulation speed of gas particles inside of a gas purification system for xenon. Secondly, it is used for rapid estimating of the separation performance of a distillation system.

  17. 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.

  18. Separation and purification of xenon

    DOEpatents

    Schlea, deceased, Carl Solomon

    1978-03-14

    Xenon is separated from a mixture of xenon and krypton by extractive distillation using carbon tetrafluoride as the partitioning agent. Krypton is flushed out of the distillation column with CF.sub.4 in the gaseous overhead stream while purified xenon is recovered from the liquid bottoms. The distillation is conducted at about atmospheric pressure or at subatmospheric pressure.

  19. 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 (ββ 0 ν) 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.

  20. Stimulated Emission of Inert Gas Mixtures in the VUV Range

    NASA Astrophysics Data System (ADS)

    Gerasimov, G. N.; Krylov, B. E.; Hallin, R.; Morozov, A. O.; Arnesen, A.; Heijkenskjold, F.

    2002-02-01

    Amplification properties of continuous VUV emission of cooled discharge in mixtures of heavy inert gases are studied experimentally. The discharge current is 10 50 mA, the pressure is 100 GPa. Results pointing to amplification near the resonance line of xenon λ=146.96 nm are obtained. The amplification coefficient is measured to be κ=0.1 cm-1. The problem of radiation outcoupling from the active medium remains to be solved for practical implementation of a VUV laser.

  1. 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.

  2. PHD TUTORIAL: Heteronuclear quantum gas mixtures

    NASA Astrophysics Data System (ADS)

    Ospelkaus, C.; Ospelkaus, S.

    2008-10-01

    In this PhD tutorial, we present experiments with quantum degenerate mixtures of fermionic and bosonic atoms in three-dimensional optical lattices. This heteronuclear quantum gas mixture offers a wide range of possibilities for quantum simulation, implementation of condensed matter Hamiltonians, quantum chemistry and ultimately dense and quantum degenerate dipolar molecular samples. We show how quantum degenerate mixtures of 40K and 87Rb are created in the experiment. We analyse stages of evaporative cooling and show how a dynamic mean-field collapse occurs during the final stage of the evaporation (Ospelkaus et al 2006 Phys. Rev. Lett. 96 020401) as a result of attractive interactions. The particle numbers observed in our experiment have only been limited by this mean-field collapse, resulting in an excellent starting point for our experiments. We explore magnetic-field-induced Feshbach resonances and demonstrate tuning of interactions (Ospelkaus et al 2006 Phys. Rev. Lett. 97 120403) between 40K and 87Rb by means of heteronuclear Feshbach resonances. We observe both stable attractively and repulsively interacting mixtures. We analyse the mean-field energy of the condensate and find qualitative agreement with a simple model. By making the interaction strong and attractive, we induce a mean-field collapse of the mixture. For strong and repulsive interactions, we observe phase separation of the mixture. When loaded into a 3D optical lattice, a whole zoo of novel quantum phases has been predicted for Fermi-Bose mixtures. We present the first realization of Fermi-Bose mixtures in 3D optical lattices as a novel quantum many-body system (Ospelkaus et al 2006 Phys. Rev. Lett. 96 180403). We study the phase coherence of the bosonic cloud in the 3D optical lattice as a function of the amount of fermionic atoms simultaneously trapped in the lattice. We observe a loss of phase coherence at much lower lattice depth than for a pure bosonic cloud and discuss possible theoretical scenarios including adiabatic processes, mean-field Fermi-Bose-Hubbard scenarios and disorder-enhanced localization scenarios. After considering this many-body limit of mixtures in lattices, we show how fermionic heteronuclear Feshbach molecules can be created in the optical lattice (Ospelkaus et al 2006 Phys. Rev. Lett. 97 120402) as a crucial step towards all ground-state dense dipolar molecular samples. We develop rf association as a novel molecule association technique, measure the binding energy, lifetime and association efficiency of the molecules. We develop a simple theoretical single-channel model of the molecules trapped in the lattice (Deuretzbacher et al 2008 Phys. Rev. A 77 032726) which gives an excellent quantitative agreement with the experimental data.

  3. SPALAX new generation: New process design for a more efficient xenon production system for the CTBT noble gas network.

    PubMed

    Topin, Sylvain; Greau, Claire; Deliere, Ludovic; Hovesepian, Alexandre; Taffary, Thomas; Le Petit, Gilbert; Douysset, Guilhem; Moulin, Christophe

    2015-11-01

    The SPALAX (Système de Prélèvement Automatique en Ligne avec l'Analyse du Xénon) is one of the systems used in the International Monitoring System of the Comprehensive Nuclear Test Ban Treaty (CTBT) to detect radioactive xenon releases following a nuclear explosion. Approximately 10 years after the industrialization of the first system, the CEA has developed the SPALAX New Generation, SPALAX-NG, with the aim of increasing the global sensitivity and reducing the overall size of the system. A major breakthrough has been obtained by improving the sampling stage and the purification/concentration stage. The sampling stage evolution consists of increasing the sampling capacity and improving the gas treatment efficiency across new permeation membranes, leading to an increase in the xenon production capacity by a factor of 2-3. The purification/concentration stage evolution consists of using a new adsorbent Ag@ZSM-5 (or Ag-PZ2-25) with a much larger xenon retention capacity than activated charcoal, enabling a significant reduction in the overall size of this stage. The energy consumption of the system is similar to that of the current SPALAX system. The SPALAX-NG process is able to produce samples of almost 7 cm(3) of xenon every 12 h, making it the most productive xenon process among the IMS systems. PMID:26197348

  4. Dusty Plasma Structures in Gas Mixtures

    SciTech Connect

    Popova, D. V.; Antipov, S. N.; Petrov, O. F.; Fortov, V. E.

    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.

  5. Acoustic composition sensor for cryogenic gas mixtures

    NASA Technical Reports Server (NTRS)

    Shakkottai, P.; Kwack, E. Y.; Luchik, T. S.; Back, L. H.

    1991-01-01

    An acoustic sensor useful for the determination of the composition of a gaseous binary mixture in cryogenic liquid spills has been characterized. One version of the instrument traps a known mixture of helium and nitrogen at ambient temperature in a tube which is interrogated by sonic pulses to determine the speed of sound and hence the composition. Experimental data shows that this sensor is quite accurate. The second version uses two unconfined microphones which sense sound pulses. Experimental data acquired during mixing when liquid nitrogen is poured into a vessel of gaseous helium is presented. Data during transient cooling of the tubular sensor containing nitrogen when the sensor is dipped into liquid nitrogen and during transient warm-up when the sensor is withdrawn are also presented. This sensor is being developed for use in the mixing of liquid cryogens with gas evolution in the simulation of liquid hydrogen/liquid oxygen explosion hazards.

  6. Mesoscale Backtracking by Means of Atmospheric Transport Modeling of Xenon Plumes Measured by Radionuclide Gas Stations

    NASA Astrophysics Data System (ADS)

    Armand, P. P.; Achim, P.; Taffary, T.

    2006-12-01

    The monitoring of atmospheric radioactive xenon concentration is performed for nuclear safety regulatory requirements. It is also planned to be used for the detection of hypothetical nuclear tests in the framework of the Comprehensive nuclear-Test-Ban Treaty (CTBT). In this context, the French Atomic Energy Commission designed a high sensitive and automated fieldable station, named SPALAX, to measure the activity concentrations of xenon isotopes in the atmosphere. SPALAX stations were set up in Western Europe and have been operated quite continuously for three years or more, detecting principally xenon-133 and more scarcely xenon-135, xenon-133m and xenon-131m. There are around 150 nuclear power plants in the European Union, research reactors, reprocessing plants, medical production and application facilities releasing radioactive xenon in normal or incidental operations. A numerical study was carried out aiming to explain the SPALAX measurements. The mesoscale Atmospheric Transport Modelling involves the MM5 suite (PSU- NCAR) to predict the wind fields on nested domains, and FLEXPART, a 3D Lagrangian particle dispersion code, used to simulate the backward transport of xenon plumes detected by the SPALAX. For every event of detection, at least one potential xenon source has a significant efficiency of emission. The identified likely sources are located quite close to the SPALAX stations (some tens of kilometres), or situated farther (a few hundreds of kilometres). A base line of some mBq per cubic meter in xenon-133 is generated by the nuclear power plants. Peaks of xenon-133 ranging from tens to hundreds of mBq per cubic meter originate from a radioisotope production facility. The calculated xenon source terms required to obtain the SPALAX measurements are discussed and seem consistent with realistic emissions from the xenon sources in Western Europe.

  7. Is xenon eldest?

    NASA Technical Reports Server (NTRS)

    Zahnle, K.

    1994-01-01

    It is well known that the solubility of noble gases in magmas decreases with increasing atomic weight. Xenon, the weightiest of the stable noble gases, is the least soluble atmospheric gas in magma. It is not unreasonable to suppose that the noble gases should have degassed from (or equilibrated with) a bubbling mantle in order of increasing solubility, such that xenon was the most rapidly degassed and helium the least. The apparent relative ages of the famous radiogenic noble gas isotopes agrees, at least qualitatively, with this premise. When atmospheric loss processes are assigned their proper place, several long-standing xenonological puzzles become added evidence for xenon's relative antiquity. Xenon being the afore-mentioned sense the oldest atmospheric gas, will have been most greatly subject to escape, be it impact-driven or EUV-driven. Nonradiogenic xenon's pronounced isotopic fractionation has already been attributed to escape; why it should be more fractionated than krypton would be assigned to xenon's greater atmospheric age. The small atmospheric inventory of xenon relative to the other nonradiogenic noblegases, known as the 'missing xenon' problem, could easily be explained by differential escape. The relatively tiny atmospheric inventories of the radiogenic daughter products of 129 Iodine and 244 Plutonium, both much smaller than would be expected from the inferred abundances of the parents in meteorites, offer a third and fourth data to support the hypothesis that Earth has lost most of its xenon.

  8. Is xenon eldest?

    NASA Astrophysics Data System (ADS)

    Zahnle, K.

    It is well known that the solubility of noble gases in magmas decreases with increasing atomic weight. Xenon, the weightiest of the stable noble gases, is the least soluble atmospheric gas in magma. It is not unreasonable to suppose that the noble gases should have degassed from (or equilibrated with) a bubbling mantle in order of increasing solubility, such that xenon was the most rapidly degassed and helium the least. The apparent relative ages of the famous radiogenic noble gas isotopes agrees, at least qualitatively, with this premise. When atmospheric loss processes are assigned their proper place, several long-standing xenonological puzzles become added evidence for xenon's relative antiquity. Xenon being the afore-mentioned sense the oldest atmospheric gas, will have been most greatly subject to escape, be it impact-driven or EUV-driven. Nonradiogenic xenon's pronounced isotopic fractionation has already been attributed to escape; why it should be more fractionated than krypton would be assigned to xenon's greater atmospheric age. The small atmospheric inventory of xenon relative to the other nonradiogenic noblegases, known as the 'missing xenon' problem, could easily be explained by differential escape. The relatively tiny atmospheric inventories of the radiogenic daughter products of 129 Iodine and 244 Plutonium, both much smaller than would be expected from the inferred abundances of the parents in meteorites, offer a third and fourth data to support the hypothesis that Earth has lost most of its xenon.

  9. HDT mixtures treatment strategies by gas chromatography

    SciTech Connect

    Laquerbe, C.; Contreras, S.; Demoment, J.

    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)

  10. Inhalation pressure distributions for medical gas mixtures calculated in an infant airway morphology model.

    PubMed

    Gouinaud, Laure; Katz, Ira; Martin, Andrew; Hazebroucq, Jean; Texereau, Jolle; Caillibotte, Georges

    2015-01-01

    A numerical pressure loss model previously used for adult human airways has been modified to simulate the inhalation pressure distribution in a healthy 9-month-old infant lung morphology model. Pressure distributions are calculated for air as well as helium and xenon mixtures with oxygen to investigate the effects of gas density and viscosity variations for this age group. The results indicate that there are significant pressure losses in infant extrathoracic airways due to inertial effects leading to much higher pressures to drive nominal flows in the infant airway model than for an adult airway model. For example, the pressure drop through the nasopharynx model of the infant is much greater than that for the nasopharynx model of the adult; that is, for the adult-versus-child the pressure differences are 0.08 cm H2O versus 0.4 cm H2O, 0.16 cm H2O versus 1.9 cm H2O and 0.4 cm H2O versus 7.7 cm H2O, breathing helium-oxygen (78/22%), nitrogen-oxygen (78/22%) and xenon-oxygen (60/40%), respectively. Within the healthy lung, viscous losses are of the same order for the three gas mixtures, so the differences in pressure distribution are relatively small. PMID:24697250

  11. First proof of topological signature in the high pressure xenon gas TPC with electroluminescence amplification for the NEXT experiment

    NASA Astrophysics Data System (ADS)

    Ferrario, P.; Laing, A.; López-March, N.; Gómez-Cadenas, J. J.; Álvarez, V.; Azevedo, C. D. R.; Borges, F. I. G.; Cárcel, S.; Cebrián, S.; Cervera, A.; Conde, C. A. N.; Dafni, T.; Díaz, J.; Diesburg, M.; Esteve, R.; Fernandes, L. M. P.; Ferreira, A. L.; Freitas, E. D. C.; Gehman, V. M.; Goldschmidt, A.; González-Díaz, D.; Gutiérrez, R. M.; Hauptman, J.; Henriques, C. A. O.; Hernando Morata, J. A.; Irastorza, I. G.; Labarga, L.; Lebrun, P.; Liubarsky, I.; Lorca, D.; Losada, M.; Luzón, G.; Marí, A.; Martín-Albo, J.; Martínez-Lema, G.; Martínez, A.; Miller, T.; Monrabal, F.; Monserrate, M.; Monteiro, C. M. B.; Mora, F. J.; Moutinho, L. M.; Muñoz Vidal, J.; Nebot-Guinot, M.; Novella, P.; Nygren, D.; Para, A.; Pérez, J.; Pérez Aparicio, J. L.; Querol, M.; Renner, J.; Ripoll, L.; Rodríguez, J.; Santos, F. P.; dos Santos, J. M. F.; Serra, L.; Shuman, D.; Simón, 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.; Yepes-Ramírez, H.

    2016-01-01

    The NEXT experiment aims to observe the neutrinoless double beta decay of 136Xe in a high-pressure xenon gas TPC using electroluminescence (EL) to amplify the signal from ionization. One of the main advantages of this technology is the possibility to reconstruct the topology of events with energies close to Q ββ . This paper presents the first demonstration that the topology provides extra handles to reject background events using data obtained with the NEXT-DEMO prototype.

  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. Dark matter directionality revisited with a high pressure xenon gas detector

    SciTech Connect

    Mohlabeng, Gopolang; Kong, Kyoungchul; Li, Jin; Para, Adam; Yoo, Jonghee

    2015-07-20

    An observation of the anisotropy of dark matter interactions in a direction-sensitive detector would provide decisive evidence for the discovery of galactic dark matter. Directional information would also provide a crucial input to understanding its distribution in the local Universe. Most of the existing directional dark matter detectors utilize particle tracking methods in a low-pressure gas time projection chamber. These low pressure detectors require excessively large volumes in order to be competitive in the search for physics beyond the current limit. In order to avoid these volume limitations, we consider a novel proposal, which exploits a columnar recombination effect in a high-pressure gas time projection chamber. The ratio of scintillation to ionization signals observed in the detector carries the angular information of the particle interactions. In this paper, we investigate the sensitivity of a future directional detector focused on the proposed high-pressure Xenon gas time projection chamber. We study the prospect of detecting an anisotropy in the dark matter velocity distribution. We find that tens of events are needed to exclude an isotropic distribution of dark matter interactions at 95% confidence level in the most optimistic case with head-to-tail information. However, one needs at least 10-20 times more events without head-to-tail information for light dark matter below ~50 GeV. For an intermediate mass range, we find it challenging to observe an anisotropy of the dark matter distribution. Our results also show that the directional information significantly improves precision measurements of dark matter mass and the elastic scattering cross section for a heavy dark matter.

  14. Dark matter directionality revisited with a high pressure xenon gas detector

    DOE PAGESBeta

    Mohlabeng, Gopolang; Kong, Kyoungchul; Li, Jin; Para, Adam; Yoo, Jonghee

    2015-07-20

    An observation of the anisotropy of dark matter interactions in a direction-sensitive detector would provide decisive evidence for the discovery of galactic dark matter. Directional information would also provide a crucial input to understanding its distribution in the local Universe. Most of the existing directional dark matter detectors utilize particle tracking methods in a low-pressure gas time projection chamber. These low pressure detectors require excessively large volumes in order to be competitive in the search for physics beyond the current limit. In order to avoid these volume limitations, we consider a novel proposal, which exploits a columnar recombination effect inmore » a high-pressure gas time projection chamber. The ratio of scintillation to ionization signals observed in the detector carries the angular information of the particle interactions. In this paper, we investigate the sensitivity of a future directional detector focused on the proposed high-pressure Xenon gas time projection chamber. We study the prospect of detecting an anisotropy in the dark matter velocity distribution. We find that tens of events are needed to exclude an isotropic distribution of dark matter interactions at 95% confidence level in the most optimistic case with head-to-tail information. However, one needs at least 10-20 times more events without head-to-tail information for light dark matter below ~50 GeV. For an intermediate mass range, we find it challenging to observe an anisotropy of the dark matter distribution. Our results also show that the directional information significantly improves precision measurements of dark matter mass and the elastic scattering cross section for a heavy dark matter.« less

  15. Modelling the behaviour of microbulk Micromegas in xenon/trimethylamine gas

    NASA Astrophysics Data System (ADS)

    Ruiz-Choliz, E.; González-Díaz, D.; Diago, A.; Castel, J.; Dafni, T.; Herrera, D. C.; Iguaz, F. J.; Irastorza, I. G.; Luzón, G.; Mirallas, H.; Şahin, Ö.; Veenhof, R.

    2015-11-01

    We model the response of a state of the art micro-hole single-stage charge amplification device ('microbulk' Micromegas) in a gaseous atmosphere consisting of xenon/trimethylamine at various concentrations and pressures. The amplifying structure, made with photo-lithographic techniques similar to those followed in the fabrication of gas electron multipliers (GEMs), consisted of a 100 μm-side equilateral-triangle pattern with 50 μm-diameter holes placed at its vertexes. Once the primary electrons are guided into the holes by virtue of an optimized field configuration, avalanches develop along the 50 μm-height channels etched out of the original doubly copper-clad polyimide foil. In order to properly account for the strong field gradients at the holes' entrance as well as for the fluctuations of the avalanche process (that ultimately determine the achievable energy resolution), we abandoned the hydrodynamic framework, resorting to a purely microscopic description of the electron trajectories as obtained from elementary cross-sections. We show that achieving a satisfactory description needs additional assumptions about atom-molecule (Penning) transfer reactions and charge recombination to be made.

  16. Barium Ion Extraction and Identification from Laser Induced Fluorescence in Gas for the Enriched Xenon Observatory

    NASA Astrophysics Data System (ADS)

    Rollin, Etienne

    The scientific community is increasingly interested in neutrinoless double beta decay. A potential measurement of the decay rate would determine the neutrino mass and would be sensitive to some extensions of the Standard Model of particle physics. Unfortunately, the decay rate is very low and competes with natural and cosmogenic radioactivity. This thesis presents a technique that eliminates such background events. It is performed by observing the barium ion daughter from the double beta decay of xenon-136 using laser induced fluorescence. The technique is very complex and requires an excellent understanding of the barium ion spectroscopy and its chemistry in the vicinity of other molecules. Such a technique will become a unique advantage over other neutrinoless double beta decay experiments, especially if the neutrino mass is low. This thesis describes three main topics. The first one describes simulations of ionizing electrons in xenon to determine the size of a gas phase detector for a neutrinoless double beta decay measurement. It has been determined that a meter size detector would contain most electron tracks. Then, it describes the design of two barium ion sources, one relying on electric discharges across two electrodes and the other one using a high energy pulsed laser. From those sources, the spectroscopy of barium ions was studied. The branching ratio of the 62S1/2 -- ---6 2P1/2 transition was found to be 74 +/- 4%. By adding argon in the chamber, the lineshift of the transition due to collisions was found to be -132 MHz/torr while the broadening rate was 23 MHz/torr. Finally, the most interesting topic is the production of doubly charged barium ions using an electrospray source. From it, ions were extracted to vacuum in a mass spectrometer and charge conversion was achieved using triethylamine. The efficiency of the conversion of Ba+ to Ba ++ was almost 100%, with a cross-section between 1.69 x 10 -18 m2 and 2.21 x 10-18 m 2 without forming any molecules.

  17. Retention of Xenon in Quartz and Earth's Missing Xenon

    NASA Astrophysics Data System (ADS)

    Sanloup, Chrystèle; Schmidt, Burkhard C.; Perez, Eva Maria Chamorro; Jambon, Albert; Gregoryanz, Eugene; Mezouar, Mohamed

    2005-11-01

    The reactivity of xenon with terrestrial oxides was investigated by in situ synchrotron x-ray diffraction. At high temperature (T > 500 kelvin), some silicon was reduced, and the pressure stability of quartz was expanded, attesting to the substitution of some xenon for silicon. When the quartz was quenched, xenon diffused out and only a few weight percent remained trapped in samples. These results show that xenon can be covalently bonded to oxygen in quartz in the lower continental crust, providing an answer to the missing xenon problem; synthesis paths of rare gas compounds are also opened.

  18. The narrow pulse approximation and long length scale determination in xenon gas diffusion NMR studies of model porous media

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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 (approximately 1-1.5 bead diameters). The Pade approximation can be used as a reference for expected xenon D(t) data between the short and the long time limits, allowing us to explore deviations from the expected behavior at intermediate times as a result of finite sample size effects. Finally, the application of the Pade interpolation between the long and the short time asymptotic limits yields a fitted length scale (the Pade length), which is found to be approximately 0.13b for all bead packs, where b is the bead diameter. c. 2002 Elsevier Sciences (USA).

  19. Electrical Breakdown in a Martian Gas Mixture

    NASA Technical Reports Server (NTRS)

    Buhler, C. R.; Calle, C. I.; Nelson, E.

    2003-01-01

    The high probability for dust interactions during Martian dust storms and dust devils combined with the cold, dry climate of Mars most likely result in airborne dust that is highly charged. On Earth, potential gradients up to 5 kV/m have been recorded and in some cases resulted in lightning. Although the Martian atmosphere is not conducive to lightning generation, it is widely believed that electrical discharge in the form of a corona occurs. In order to understand the breakdown of gases, Paschen measurements are taken which relate the minimum potential required to spark across a gap between two electrodes. The minimum potential is plotted versus the pressure-distance value for electrodes of a given geometry. For most gases, the potential decreases as the pressure decreases. For CO2, the minimum in the curve happens to be at Mars atmospheric pressures (5-7 mm Hg) for many distances and geometries. However, a very small amount (<0.1%) of mixing gases radically changes the curve, as noted by Leach. Here, we present the first experimental results of a Paschen curve for a Mars gas mixture compared with 100% pure CO2.

  20. 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.

  1. Formation of Structured Water and Gas Hydrate by the Use of Xenon Gas in Vegetable Tissue

    NASA Astrophysics Data System (ADS)

    Ando, Hiroko; Suzuki, Toru; Kawagoe, Yoshinori; Makino, Yoshio; Oshita, Seiichi

    Freezing is a valuable technique for food preservation. However, vegetables are known to be softening remarkably after freezing and thawing process. It is expected to find alternative technique instead of freezing. Recently, the application of structured water and/or gas hydrate had been attempted to prolong the preservation of vegetable. In this study, the formation process of structure water and/or gas hydrate in pure water and carrot tissue was investigated by using NMR relaxation times, T1 and T2, of which applying condition was up to 0.4MPa and 0.8MPa at 5oC. Under the pressure of 0.4MPa, no gas hydrate was appeared, however, at 0.8MPa, formation of gas hydrate was recognized in both water and carrot tissue. Once the gas hydrate formation process in carrot tissue started, T1 and T2 increased remarkably. After that, as the gas hydrate developed, then T1 and T2 turned to decrease. Since this phenomenon was not observed in pure water, it is suggested that behavior of NMR relaxation time just after the formation of gas hydrate in carrot tissue may be peculiar to compartment system such as inter and intracellular spaces.

  2. Studies of xenon ECR plasma: search for a better understanding of the gas-mixing and anomalous effects

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Mal, Kedar; Kanjilal, D.

    2014-12-01

    Pure and oxygen-mixed xenon plasmas were produced using 10 GHz all-permanent-magnet electron cyclotron resonance (ECR) ion source. The charge state distributions (CSDs) of highly abundant isotopes (129Xe, 131 Xe and 132 Xe) were studied by extracting the ions from the plasma and analyzed them in mass and energy using a large acceptance analyzer-switching dipole magnet. In earlier studies (Drentje 1992 Rev. Sci. Instrum. 63 2875, Kawai et al 2001 Plasma Sources Sci. Technol. 10 451), the CSD of oxygen and nitrogen ECR plasmas showed that isotopic intensity ratio of ions varies with the charge state (anomalous effect). The anomalous effect in the pure and oxygen-mixed xenon ECR plasma was absent up to +13 charge state. With oxygen, a very small positive gas-mixing effect on the charge state beyond +8 was observed. In this paper, we present CSDs of xenon isotopes with and without oxygen mixing (at optimized ion source parameters) and compare the intensity of isotopes for various charge states to shed light on the previously noticed anomalous effect in the ECR plasma.

  3. THE RECOVERY OF URANIUM FROM GAS MIXTURE

    DOEpatents

    Jury, S.H.

    1964-03-17

    A method of separating uranium from a mixture of uranium hexafluoride and other gases is described that comprises bringing the mixture into contact with anhydrous calcium sulfate to preferentially absorb the uranium hexafluoride on the sulfate. The calcium sulfate is then leached with a selective solvent for the adsorbed uranium. (AEC)

  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. 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.

  6. Xenon forms stable compound with fluorine

    NASA Technical Reports Server (NTRS)

    Claassen, H. H.; Malm, J. G.; Selig, H. H.

    1966-01-01

    Experiments show that xenon and fluorine combine readily at 400 deg C to form xenon tetrafluoride, which is colorless, crystalline, chemically stable and solid at room temperature. This process can be used for the separation of xenon from mixtures with other noble gases.

  7. Inferential determination of various properties of a gas mixture

    DOEpatents

    Morrow, Thomas B.; Behring, II, Kendricks A.

    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.

  8. 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.

  9. Optimization of Dual-Energy Xenon-CT for Quantitative Assessment of Regional Pulmonary Ventilation

    PubMed Central

    Fuld, Matthew K.; Halaweish, Ahmed; Newell, John D.; Krauss, Bernhard; Hoffman, Eric A.

    2013-01-01

    Objective Dual-energy X-ray computed tomography (DECT) offers visualization of the airways and quantitation of regional pulmonary ventilation using a single breath of inhaled xenon gas. In this study we seek to optimize scanning protocols for DECT xenon gas ventilation imaging of the airways and lung parenchyma and to characterize the quantitative nature of the developed protocols through a series of test-object and animal studies. Materials and Methods The Institutional Animal Care and Use Committee approved all animal studies reported here. A range of xenon-oxygen gas mixtures (0, 20, 25, 33, 50, 66, 100%; balance oxygen) were scanned in syringes and balloon test-objects to optimize the delivered gas mixture for assessment of regional ventilation while allowing for the development of improved three-material decomposition calibration parameters. Additionally, to alleviate gravitational effects on xenon gas distribution, we replaced a portion of the oxygen in the xenon/oxygen gas mixture with helium and compared gas distributions in a rapid-prototyped human central-airway test-object. Additional syringe tests were performed to determine if the introduction of helium had any effect on xenon quantitation. Xenon gas mixtures were delivered to anesthetized swine in order to assess airway and lung parenchymal opacification while evaluating various DECT scan acquisition settings. Results Attenuation curves for xenon were obtained from the syringe test objects and were used to develop improved three-material decomposition parameters (HU enhancement per percent xenon: Within the chest phantom: 2.25 at 80kVp, 1.7 at 100 kVp, and 0.76 at 140 kVp with tin filtration; In open air: 2.5 at 80kVp, 1.95 at 100 kVp, and 0.81 at 140 kVp with tin filtration). The addition of helium improved the distribution of xenon gas to the gravitationally non-dependent portion of the airway tree test-object, while not affecting quantitation of xenon in the three-material decomposition DECT. 40%Xe/40%He/20%O2 provided good signal-to-noise, greater than the Rose Criterion (SNR > 5), while avoiding gravitational effects of similar concentrations of xenon in a 60%O2 mixture. 80/140-kVp (tin-filtered) provided improved SNR compared with 100/140-kVp in a swine with an equivalent thoracic transverse density to a human subject with body mass index of 33. Airways were brighter in the 80/140 kVp scan (80/140Sn, 31.6%; 100/140Sn, 25.1%) with considerably lower noise (80/140Sn, CV of 0.140; 100/140Sn, CV of 0.216). Conclusion In order to provide a truly quantitative measure of regional lung function with xenon-DECT, the basic protocols and parameter calibrations needed to be better understood and quantified. It is critically important to understand the fundamentals of new techniques in order to allow for proper implementation and interpretation of their results prior to wide spread usage. With the use of an in house derived xenon calibration curve for three-material decomposition rather than the scanner supplied calibration and a xenon/helium/oxygen mixture we demonstrate highly accurate quantitation of xenon gas volumes and avoid gravitational effects on gas distribution. This study provides a foundation for other researchers to use and test these methods with the goal of clinical translation. PMID:23571834

  10. Theoretical studies of pressure broadening of alkali-metal-rare-gas mixtures.

    NASA Astrophysics Data System (ADS)

    Chung, H.-K.; Shurgalin, M.; Babb, J. F.

    1999-10-01

    Pressure broadening is investigated for alkali-metal atoms perturbed by rare gas atoms at high density. Quasi-molecular vibrational and rotational structures appear in the the far-wing spectra. Their importance to understanding energy transport in the gas and also the use of satellite structures as a diagnostic of gas conditions are explored. In the quasi-static limit, the pair-wise interacting alkali-metal atoms and rare gas atoms are treated as quasi-molecules and the far-wings of the broadened spectra are modeled as molecular radiation, calculated quantum-mechanically utilizing critically evaluated molecular data. We also extend our quantum-mechanical approach to a unified theory which can explain not only the far wings but also the core of the broadened lines. Our results are compared with experimental results for sodium-xenon gas mixtures and their relevance to high-pressure sodium lamps will be considered. This research has been carried out in collaboration with OSRAM SYLVANIA Inc. and is supported in part by the NSF.

  11. Antiapoptotic activity of argon and xenon

    PubMed Central

    Spaggiari, Sabrina; Kepp, Oliver; Rello-Varona, Santiago; Chaba, Kariman; Adjemian, Sandy; Pype, Jan; Galluzzi, Lorenzo; Lemaire, Marc; Kroemer, Guido

    2013-01-01

    Although chemically non-reactive, inert noble gases may influence multiple physiological and pathological processes via hitherto uncharacterized physical effects. Here we report a cell-based detection system for assessing the effects of pre-defined gas mixtures on the induction of apoptotic cell death. In this setting, the conventional atmosphere for cell culture was substituted with gas combinations, including the same amount of oxygen (20%) and carbon dioxide (5%) but 75% helium, neon, argon, krypton, or xenon instead of nitrogen. The replacement of nitrogen with noble gases per se had no effects on the viability of cultured human osteosarcoma cells in vitro. Conversely, argon and xenon (but not helium, neon, and krypton) significantly limited cell loss induced by the broad-spectrum tyrosine kinase inhibitor staurosporine, the DNA-damaging agent mitoxantrone and several mitochondrial toxins. Such cytoprotective effects were coupled to the maintenance of mitochondrial integrity, as demonstrated by means of a mitochondrial transmembrane potential-sensitive dye and by assessing the release of cytochrome c into the cytosol. In line with this notion, argon and xenon inhibited the apoptotic activation of caspase-3, as determined by immunofluorescence microscopy coupled to automated image analysis. The antiapoptotic activity of argon and xenon may explain their clinically relevant cytoprotective effects. PMID:23907115

  12. A note on the biological activity of the noble gas compound xenon trioxide.

    NASA Technical Reports Server (NTRS)

    Siegel, S. M.; Smith, C. W.

    1972-01-01

    Comparison of xenon trioxide for toxicity in the few common oxidants using three bioassays. On a molar basis XeO3 and HOCl were similar, but XeO3 was less active than expected when comparisons were based on normality.

  13. High-pressure Xenon Gas Electroluminescent TPC Concept for Simultaneous Searches for Neutrino-less Double Beta Decay & WIMP Dark Matter

    NASA Astrophysics Data System (ADS)

    Nygren, David

    2013-04-01

    Xenon is an especially attractive candidate for both direct WIMP and 0- decay searches. Although the current trend has exploited the liquid phase, gas phase xenon offers some remarkable performance advantages for energy resolution, topology visualization, and discrimination between electron and nuclear recoils. The NEXT-100 experiment, now beginning construction in the Canfranc Underground Laboratory, Spain, will operate at 12 bars with 100 kg of ^136Xe for the 0- decay search. I will describe recent results with small prototypes, indicating that NEXT-100 can provide about 0.5% FWHM energy resolution at the decay 2457.83 keV Q-value, as well as rejection of -rays by topology. However, sensitivity goals for WIMP dark matter and 0- decay searches indicate the need for ton-scale active masses; NEXT-100 provides the springboard to reach this scale with xenon gas. I describe a scenario for performing both searches in a single high-pressure ton-scale xenon gas detector, without significant compromise to either. In addition, -- even in a single, ton-scale, high-pressure xenon gas TPC, an intrinsic sensitivity to the nuclear recoil direction may exist -- plausibly offering an advance of more than two orders of magnitude relative to current low-pressure TPC concepts. I argue that, in an era of deepening fiscal austerity, such a dual-purpose detector may be possible, at acceptable cost, within the time frame of interest, and deserves our collective attention.

  14. Composition for absorbing hydrogen from gas mixtures

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Lee, Myung W.

    1999-01-01

    A hydrogen storage composition is provided which defines a physical sol-gel matrix having an average pore size of less than 3.5 angstroms which effectively excludes gaseous metal hydride poisons while permitting hydrogen gas to enter. The composition is useful for separating hydrogen gas from diverse gas streams which may have contaminants that would otherwise render the hydrogen absorbing material inactive.

  15. Thermal Conductivity of Gas Mixtures in Chemical Equilibrium

    NASA Technical Reports Server (NTRS)

    Brokaw, Richard S.

    1960-01-01

    The expression for the thermal conductivity of gas mixtures in chemical equilibrium is presented in a simpler and less restrictive form. This new form is shown to be equivalent to the previous equations.

  16. 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.

  17. 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.

  18. 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

  19. Improved 02/H2 Gas Mixture Sensor

    NASA Technical Reports Server (NTRS)

    Moulthrop, L. C.

    1983-01-01

    Monitor of mixture concentrations uses catalyzed and uncatalyzed temperature probe. Sensor includes Pt-catalyzed temperature probe mounted in line with similar uncatalyzed temperature probe. Use of common temperature probes and standard, flareless, high-pressure tubefittings resulted in design conductive to installation in almost any system. Suitable for use in regenerative fuel cells, life-support systems, and other closed systems.

  20. Propagation of stationary nonadiabatic combustion waves in a gas mixture

    SciTech Connect

    Lyubchenko, V.I.; Marchenko, G.N.

    1987-06-01

    A laminar diffusion flame cannot propagate in narrow channels due to heat losses to the environment. In this case there are limit phenomena connected with the existence of a critical velocity for propagation of the combustion wave and a critical diameter for the tube along which the combusting gas mixture moves. In this paper a mathematical model is constructed depicting these boundary conditions in a steady-state theory of flame propagation along a reacting homogeneous gas mixture in tubes when there are lateral heat losses. Nonadiabatic stationary combustion waves in the mixture are determined.

  1. In situ measurements of krypton in xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed

    NASA Astrophysics Data System (ADS)

    Brown, E.; Rosendahl, S.; Huhmann, C.; Weinheimer, C.; Kettling, H.

    2013-02-01

    A new method for measuring trace amounts of krypton in xenon using a cold trap with a residual gas analyzer has been developed, which achieves an increased sensitivity by temporarily reducing the pumping speed while expending a minimal amount of xenon. By partially closing a custom built butterfly valve between the measurement chamber and the turbomolecular pump, a sensitivity of 40 ppt has been reached. This method has been tested on an ultra-pure gas sample from Air Liquide with an unknown intrinsic krypton concentration, yielding a krypton concentration of 330±200 ppt.

  2. Novel Sorbent Development and Evaluation for the Capture of Krypton and Xenon from Nuclear Fuel Reprocessing Off-Gas Streams

    SciTech Connect

    Troy G. Garn; Mitchell R. Greenhalgh; Jack D. Law

    2013-09-01

    The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, INL sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up.

  3. Novel Sorbent Development and Evaluation for the Capture of Krypton and Xenon from Nuclear Fuel Reprocessing Off-Gas Streams

    SciTech Connect

    Troy G. Garn; Mitchell R. Greenhalgh; Jack D. Law

    2013-10-01

    The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, INL sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up.

  4. Novel sorbent development and evaluation for the capture of krypton and xenon from nuclear fuel reprocessing off-gas stream

    SciTech Connect

    Garn, T.G.; Greenhalgh, M.R.; Law, J.D.

    2013-07-01

    The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, Idaho National Laboratory sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up. (authors)

  5. 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.

  6. Diffusion in helium-noble gas mixtures I. Almost Lorentzian mixtures

    NASA Astrophysics Data System (ADS)

    Wahby, A. S. M.; Abdel-Rahman, M.; Los, J.

    1982-05-01

    Diffusion coefficients have been measured of almost Lorentzian binary mixtures of He and the noble gases Ne, Ar, Kr and Xe. Measurements have been performed in the temperature range from 237 K to 420 K. The agreement with other experimental data is very satisfactory. A comparison with experimental thermal diffusion data on the same mixtures shows that the relation for Lorentzian mixtures. α L= 2- {∂ In D 12}/{∂ In T }p is quite accurate for the heavier helium-noble gas mixtures. Comparison of the experimentally determined function 2- {∂ In D 12}/{∂ In T }p with theoretical calculations for several model potentials shows a semi-quantitative agreement between theory and experiment. The experimental curves indicate a great similarity between the interaction potentials of helium with the different noble gas atoms.

  7. Portable device for preparation and delivery of gas mixtures.

    PubMed

    Misaghi, I J; Stowell, L J

    1991-03-01

    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 O(2), CO(2), and N(2) 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. PMID:16348449

  8. Fluorine Compounds of Xenon and Radon.

    PubMed

    Chernick, C L; Claassen, H H; Fields, P R; Hyman, H H; Malm, J G; Manning, W M; Matheson, M S; Quarterman, L A; Schreiner, F; Selig, H H; Sheft, I; Siegel, S; Sloth, E N; Stein, L; Studier, M H; Weeks, J L; Zirin, M H

    1962-10-12

    Xenon and fluorine combine readily. Xenon tetrafluoride is a colorless crystalline material, stable at room remperature. The existence of at least one other fluoride and two oxyfluorides has been demonstrated. The heaviest "inert gas," radon, also reacts with fluorine, yielding a compound less volatile than xenon tetrafluoride. PMID:17818399

  9. 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

  10. Gas sampling system for reactive gas-solid mixtures

    DOEpatents

    Daum, Edward D.; Downs, William; Jankura, Bryan J.; McCoury, Jr., John M.

    1990-01-01

    An apparatus and method for sampling gas containing a reactive particulate solid phase flowing through a duct and for communicating a representative sample to a gas analyzer. A sample probe sheath 32 with an angular opening 34 extends vertically into a sample gas duct 30. The angular opening 34 is opposite the gas flow. A gas sampling probe 36 concentrically located within sheath 32 along with calibration probe 40 partly extends in the sheath 32. Calibration probe 40 extends further in the sheath 32 than gas sampling probe 36 for purging the probe sheath area with a calibration gas during calibration.

  11. Gas sampling system for reactive gas-solid mixtures

    DOEpatents

    Daum, Edward D.; Downs, William; Jankura, Bryan J.; McCoury, Jr., John M.

    1989-01-01

    An apparatus and method for sampling a gas containing a reactive particulate solid phase flowing through a duct and for communicating a representative sample to a gas analyzer. A sample probe sheath 32 with an angular opening 34 extends vertically into a sample gas duct 30. The angular opening 34 is opposite the gas flow. A gas sampling probe 36 concentrically located within sheath 32 along with calibration probe 40 partly extend in the sheath 32. Calibration probe 40 extends further in the sheath 32 than gas sampling probe 36 for purging the probe sheath area with a calibration gas during calibration.

  12. Propagation of radiation pulses through gas-plasma mixtures

    NASA Astrophysics Data System (ADS)

    Marzlin, Karl-Peter; Panwar, Anuraj; Razul, M. Shajahan G.; Sanders, Barry C.

    2016-04-01

    We determine the linear optical susceptibility of a radiation pulse propagating through a mixture of a gas of atoms or molecules and a plasma. For a specific range of radiation and plasma frequencies, resonant generation of volume plasmons significantly amplifies the radiation intensity. The conditions for resonant amplification are derived from the dispersion relations in the mixture, and the amplification is demonstrated in a numerical simulation of pulse propagation.

  13. Recovery of purified helium or hydrogen from gas mixtures

    DOEpatents

    Merriman, J.R.; Pashley, J.H.; Stephenson, M.J.; Dunthorn, D.I.

    1974-01-15

    A process is described for the removal of helium or hydrogen from gaseous mixtures also containing contaminants. The gaseous mixture is contacted with a liquid fluorocarbon in an absorption zone maintained at superatomspheric pressure to preferentially absorb the contaminants in the fluorocarbon. Unabsorbed gas enriched in hydrogen or helium is withdrawn from the absorption zone as product. Liquid fluorocarbon enriched in contaminants is withdrawn separately from the absorption zone. (10 claims)

  14. Drift velocities of electrons in methane-inert-gas mixtures

    NASA Astrophysics Data System (ADS)

    Foreman, L.; Kleban, P.; Schmidt, L. D.; Davis, H. T.

    1981-03-01

    The drift of electrons in mixtures of methane with argon and helium is measured with a double shutter drift tube as a function of methane composition and electric field-pressure ratio Ep. At certain concentrations, inelastic scattering by methane causes a maximum in the drift velocity as a function of Ep. As the methane mole fraction decreases, the drift velocity maximum decreases and moves to lower values of Ep. In the argon mixtures, the drift velocity at low Ep is greater than it is in either pure gas. Comparision is made with direct numerical solutions of the Boltzmann equation for the mixtures. When the methane mole fractions are appropriately chosen, the data obey roughly a scaling law relating the electron drift velocity versus Ep in a methane-argon mixture with VD versus Ep in a methane-helium mixture.

  15. Recent nuclear pumped laser results. [gas mixtures and laser plasmas

    NASA Technical Reports Server (NTRS)

    Miley, G. H.; Wells, W. E.; Akerman, M. A.; Anderson, J. H.

    1976-01-01

    Recent direct nuclear pumped laser research has concentrated on experiments with three gas mixtures (Ne-N2, He-Ne-O2, and He-Hg). One mixture has been made to lase and gain has been achieved with the other two. All three of these mixtures are discussed with particular attention paid to He-Hg. Of interest is the 6150-angstroms ion transition in Hg(+). The upper state of this transition is formed directly by charge transfer and by Penning ionization.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Acoustics and precondensation phenomena in gas-vapor saturated mixtures.

    PubMed

    Guianvarc'h, C; Bruneau, M; Gavioso, R M

    2014-02-01

    Starting from fundamental hydrodynamics and thermodynamics equations for thermoviscous fluids, a new modeling procedure, which is suitable to describe acoustic propagation in gas mixtures, is presented. The model revises the boundary conditions which are appropriate to describe the condensation-evaporation processes taking place on a solid wall when one component of the mixture approaches saturation conditions. The general analytical solutions of these basic equations now give a unified description of acoustic propagation in an infinite, semi-infinite, or finite medium, throughout and beyond the boundary layers. The solutions account for the coupling between acoustic propagation and heat and concentration diffusion processes, including precondensation on the walls. The validity of the model and its predictive capability have been tested by a comparison with the description available in the literature of two particular systems (precondensation of propane and acoustic attenuation in a duct filled with an air-water vapor saturated mixture). The results of this comparison are discussed to clarify the relevance of the various physical phenomena that are involved in these processes. The model proposed here might be useful to develop methods for the acoustic determination of the thermodynamic and transport properties of gas mixtures as well as for practical applications involving gas and gas-vapor mixtures like thermoacoustics and acoustics in wet granular or porous media. PMID:25353596

  18. Acoustics and precondensation phenomena in gas-vapor saturated mixtures

    NASA Astrophysics Data System (ADS)

    Guianvarc'h, C.; Bruneau, M.; Gavioso, R. M.

    2014-02-01

    Starting from fundamental hydrodynamics and thermodynamics equations for thermoviscous fluids, a new modeling procedure, which is suitable to describe acoustic propagation in gas mixtures, is presented. The model revises the boundary conditions which are appropriate to describe the condensation-evaporation processes taking place on a solid wall when one component of the mixture approaches saturation conditions. The general analytical solutions of these basic equations now give a unified description of acoustic propagation in an infinite, semi-infinite, or finite medium, throughout and beyond the boundary layers. The solutions account for the coupling between acoustic propagation and heat and concentration diffusion processes, including precondensation on the walls. The validity of the model and its predictive capability have been tested by a comparison with the description available in the literature of two particular systems (precondensation of propane and acoustic attenuation in a duct filled with an air-water vapor saturated mixture). The results of this comparison are discussed to clarify the relevance of the various physical phenomena that are involved in these processes. The model proposed here might be useful to develop methods for the acoustic determination of the thermodynamic and transport properties of gas mixtures as well as for practical applications involving gas and gas-vapor mixtures like thermoacoustics and acoustics in wet granular or porous media.

  19. Characterization of Gas Amplification in Varied Gas Mixtures for Stacked Gas Electron Multiplier and Micromegas Detectors

    NASA Astrophysics Data System (ADS)

    Ehlers, Raymond

    2015-04-01

    Micropattern Gas Detectors (MPGDs) represent a promising group of gas amplification technologies. Utilizing large electric fields over geometries on the order of tens of micrometers, these elements can achieve large gas amplification while minimizing field distortions by minimizing the number of ions escaping from the amplification stage. Such properties are extremely useful for readout in gaseous detectors such as Time Projection Chambers. Two types of MPGDs are of particular interest, Gas Electron Multipliers (GEMs) and Micro-mesh Gaseous Structure (Micromegas) detectors. These elements may be stacked, which allows for the utilization of the best properties of both, further improving the amplification performance. We report here on the characterization of 2 GEMs stacked on top of a Micromegas. In particular, I will present the dependence of gas amplification on Micromegas voltage in various gas mixtures, as well as an investigation into stability of the elements against sparking.

  20. Pulsed electron beam propagation in argon and nitrogen gas mixture

    NASA Astrophysics Data System (ADS)

    Kholodnaya, G. E.; Sazonov, R. V.; Ponomarev, D. V.; Remnev, G. E.; Zhirkov, I. S.

    2015-10-01

    The paper presents the results of current measurements for the electron beam, propagating inside a drift tube filled in with a gas mixture (Ar and N2). The experiments were performed using the TEA-500 pulsed electron accelerator. The main characteristics of electron beam were as follows: 60 ns pulse duration, up to 200 J energy, and 5 cm diameter. The electron beam propagated inside the drift tube assembled of three sections. Gas pressures inside the drift tube were 760 ± 3, 300 ± 3, and 50 ± 1 Torr. The studies were performed in argon, nitrogen, and their mixtures of 33%, 50%, and 66% volume concentrations, respectively.

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

    PubMed Central

    Kendrick, A. H.; Laszlo, G.

    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 of TLCO either a known inspired oxygen concentration should be used, or TLCO should be corrected to a standard inspired oxygen concentration. The range of gas mixtures used in practice and the implications for cost and accuracy have been investigated. METHODS--A questionnaire was sent to 185 respiratory units in the UK requesting information on (1) the method used to estimate TLCO, (2) the manufacturer of the equipment, (3) the mixture used, (4) whether "medical quality" gas was ordered, and (5) the level of satisfaction with supplier service. RESULTS--Replies were received from 106 units. Most used the single breath breath holding method for which 17 different test mixtures were ordered. One unit also used the single breath exhalation method. Inspired oxygen ranged from 17.94% to 25%, giving a wide variation in alveolar oxygen and hence TLCO. Forty seven units ordered a specific inspired oxygen, the rest ordering "air" as balance. The cost per litre of gas varied greatly, with the mixture 14% helium, 0.28% carbon monoxide, balance air (17.9% oxygen) and 10% helium, 0.28% carbon monoxide, balance air (18.8% oxygen) being cheapest to produce. Ordering a specific inspired oxygen concentration increased the cost. Large cylinders of gas were cheaper for the same mixture. The mixture for the exhalation method was the most expensive. Sixty seven units ordered "medical quality" gas and six assumed this was supplied. Twenty nine (27%) were dissatisfied with their supplier due to (1) poor service, (2) long delivery times, (3) costs, or (4) wrongly labelled cylinders. CONCLUSIONS--It is recommended that two mixtures be available: (a) 14% helium, 0.28% carbon monoxide, balance air for a helium analyser reading up to 15%, and (b) 10% helium, 0.28% carbon monoxide, balance air for lower reading helium analysers. The mixture should be produced under a medical product licence. The advantage of the single exhalation method for routine clinical use needs to be investigated in view of the higher cost of the mixture. PMID:8211878

  2. Krypton and xenon in Apollo 14 samples - Fission and neutron capture effects in gas-rich samples

    NASA Technical Reports Server (NTRS)

    Drozd, R.; Hohenberg, C.; Morgan, C.

    1975-01-01

    Gas-rich Apollo 14 breccias and trench soil are examined for fission xenon from the decay of the extinct isotopes Pu-244 and I-129, and some samples have been found to have an excess fission component which apparently was incorporated after decay elsewhere and was not produced by in situ decay. Two samples have excess Xe-129 resulting from the decay of I-129. The excess is correlated at low temperatures with excess Xe-128 resulting from neutron capture on I-127. This neutron capture effect is accompanied by related low-temperature excesses of Kr-80 and Kr-82 from neutron capture on the bromine isotopes. Surface correlated concentrations of iodine and bromine are calculated from the neutron capture excesses.

  3. 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.

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

    DOE PAGESBeta

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

    2015-03-24

    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 offers 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 themore » 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.« less

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

    SciTech Connect

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

    2015-03-24

    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 offers 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.

  6. Handheld calculator program simplifies calculation of data for gas mixtures

    SciTech Connect

    Karger, W.

    1982-01-11

    For natural gases having several components, Elliott Co.'s handheld calculator program can characterize the gas mixture with a printout that provides its molecular weight, molar specific heat at constant pressure, pseudocritical pressure and temperature, ratio of specific heats, and adiabatic compression exponent. The program also provides for further calculations that yield specific gravity, specific heat/lb, and compressibility.

  7. 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.

  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. Corrosion behaviors of inconel 617 in hydrogen base gas mixture

    NASA Astrophysics Data System (ADS)

    Shikama, Tatsuo; Tanabe, Tatsuhiko; Fujitsuka, Masakazu; Kitajima, Masahiro; Yoshida, Heitaro; Watanabe, Ryoji

    1980-09-01

    The corrosion behavior of Inconel 617, a candidate for the structural material of heat exchanger in the high temperature gas-cooled reactor (HTGR), has been investigated at elevated temperatures in the hydrogen base gas mixture (80 pct H2 + 15 pct CO + 5 pct CO2). This gas mixture simulates the reducing gas in the direct steel making system that uses heat from HTGR in Japan. This gas has relatively high oxidizing and carburizing potentials. In the temperature range of 650 to 1000 °C Inconel 617 oxidized to form a Cr2O3 scale containing titanium oxide. The activation energy for this process is estimated to be 50 to 60 kcal/mol. The time dependence of the growth of the surface oxide scale was parabolic. The aluminum in Inconel 617 was internally oxidized. The time dependence of the internal oxidation was noticed to obey a 0.4 power rate law. Carburization was noticed at 650 and 900 °C. At 900 °C, carbides containing Si, Ti, and Mo precipitated beneath the oxide scale for gas exposure times up to 200 h. After 200 h, the formation and growth of the surface scale suppresses carburization. The thermodynamic analysis of gas atmosphere proposed by Gurry could be applied successfully to the experimental results. Some inconsistency existed mainly because of the scale formation and direct gas-metal interactions.

  11. Plasmas Generated With Gas Mixtures at the Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Calzada, M. D.; Muoz, J.; Rincn, R.; Jimnez, M.; Sez, M.

    Several applications, such as metal surface nitriding, medical instrument sterilization and chemical analysis, have been developed or improved using a gas mixture as plasmogen gas. Research carried out on these subjects covers the aspect of knowing the processes that take place in plasmas which depend on the densities of the different plasma particles and their energy values. In this paper, the results obtained from the application of spectroscopic techniques for the characterization of surface wave discharges at the atmospheric pressure, generated with more than one gas type, are presented, particularly for the Ar-He, Ar-Ne and Ar-N2 plasmas.

  12. Approximate Thermodynamics State Relations in Partially Ionized Gas Mixtures

    SciTech Connect

    Ramshaw, J D

    2003-12-30

    In practical applications, the thermodynamic state relations of partially ionized gas mixtures are usually approximated in terms of the state relations of the pure partially ionized constituent gases or materials in isolation. Such approximations are ordinarily based on an artificial partitioning or separation of the mixture into its constituent materials, with material k regarded as being confined by itself within a compartment or subvolume with volume fraction {alpha}k and possessing a fraction {beta}k of the total internal energy of the mixture. In a mixture of N materials, the quantities {alpha}k and {beta}k constitute an additional 2N--2 independent variables. The most common procedure for determining these variables, and hence the state relations for the mixture, is to require that the subvolumes all have the same temperature and pressure. This intuitively reasonable procedure is easily shown to reproduce the correct thermal and caloric state equations for a mixture of neutral (non-ionized) ideal gases. Here we wish to point out that (a) this procedure leads to incorrect state equations for a mixture of partially ionized ideal gases, whereas (b) the alternative procedure of requiring that the subvolumes all have the same temperature and free electron density reproduces the correct thermal and caloric state equations for such a mixture. These results readily generalize to the case of partially degenerate and/or relativistic electrons, to a common approximation used to represent pressure ionization effects, and to two-temperature plasmas. This suggests that equating the subvolume electron number densities or chemical potentials instead of pressures is likely to provide a more accurate approximation even in nonideal plasma mixtures.

  13. Electrochemical separation and concentration of hydrogen sulfide from gas mixtures

    DOEpatents

    Winnick, Jack; Sather, Norman F.; Huang, Hann S.

    1984-10-30

    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 -- or, in the case of H.sub.2 S, to S--. 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.

  14. Gravimetric methods for the preparation of standard gas mixtures

    NASA Astrophysics Data System (ADS)

    Milton, M. J. T.; Vargha, G. M.; Brown, A. S.

    2011-10-01

    The most widely used method for the preparation of primary standard gas mixtures involves weighing the individual components into a cylinder. We present a new mathematical description of the method and its uncertainties. We use this to demonstrate how strategies for serial dilution can be identified that minimize the uncertainty in the final mixture and show how they can be implemented practically. We review published reports of high accuracy gravimetry and give examples of relative uncertainties in the composition of standards approaching 1 part-per-million in the best cases and in the range of 100 to 1000 parts-per-million more typically.

  15. Calibration and uncertainty assessment for certified reference gas mixtures.

    PubMed

    Guenther, Franklin R; Possolo, Antonio

    2011-01-01

    The weighted least squares method to build an analysis function described in ISO 6143, Gas analysis--Comparison methods for determining and checking the composition of calibration gas mixtures, is modified to take into account the typically small number of instrumental readings that are obtained for each primary standard gas mixture used in calibration. The theoretical basis for this modification is explained, and its superior performance is illustrated in a simulation study built around a concrete example, using real data. The corresponding uncertainty assessment is obtained by application of a Monte Carlo method consistent with the guidance in the Supplement 1 to the Guide to the expression of uncertainty in measurement, which avoids the need for two successive applications of the linearizing approximation of the conventional method for uncertainty propagation. The three main steps that NIST currently uses to certify a reference gas mixture (homogeneity study, calibration, and assignment of value and uncertainty assessment), are described and illustrated using data pertaining to an actual standard reference material. PMID:21072506

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    We have extended the utility of NMR as a technique to probe porous media structure over length scales of approximately 100-2000 microm 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 pore surface-area-to-volume ratio, S/V(p), 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 approximately 0.62-0.65D(0), that could be measured over diffusion distances extending over multiple bead diameters. Measurements of D(t)/D(0) 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)/D(0) was noticeably affected by the gas pressure in the sample. Increasing the gas pressure, and hence reducing D(0) and the diffusion during the gradient pulse served to reduce the previously observed deviation of D(t)/D(0) from the S/V(p) relation. The Pade approximation is used to interpolate between the long and short time limits in D(t). While the short time D(t) points 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.

  17. Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air

    SciTech Connect

    Gulati, P.; Prakash, R.; Pal, U. N.; Kumar, M.; Vyas, V.

    2014-07-07

    A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl{sub 2} deteriorates the performance of the developed source and around 2% Cl{sub 2} in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

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

    DOEpatents

    Hupp, Joseph T.; Mulfort, Karen L.; Snurr, Randall Q.; Bae, Youn-Sang

    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.

  19. 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.

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

    DOE PAGESBeta

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

    2014-10-21

    In our 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 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. Moreover, the optimum combination involved operating one getter at 650°C to decompose the methane, and the second at 110°C to remove the hydrogen. Finally, this approach eliminatedmore » 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.« less

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

    SciTech Connect

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

    2014-10-21

    In our 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 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. Moreover, the optimum combination involved operating one getter at 650°C to decompose the methane, and the second at 110°C to remove the hydrogen. Finally, 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.

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

    SciTech Connect

    Cárdenas, Rosa Elia; Stewart, Kenneth D.; Cowgill, Donald F.

    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.

  3. 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.

  4. Pulsed electron beam propagation in argon and nitrogen gas mixture

    SciTech Connect

    Kholodnaya, G. E.; Sazonov, R. V.; Ponomarev, D. V.; Remnev, G. E.; Zhirkov, I. S.

    2015-10-15

    The paper presents the results of current measurements for the electron beam, propagating inside a drift tube filled in with a gas mixture (Ar and N{sub 2}). The experiments were performed using the TEA-500 pulsed electron accelerator. The main characteristics of electron beam were as follows: 60 ns pulse duration, up to 200 J energy, and 5 cm diameter. The electron beam propagated inside the drift tube assembled of three sections. Gas pressures inside the drift tube were 760 ± 3, 300 ± 3, and 50 ± 1 Torr. The studies were performed in argon, nitrogen, and their mixtures of 33%, 50%, and 66% volume concentrations, respectively.

  5. Diffusion and viscosity coefficients for helium. [in astrophysical gas mixtures

    NASA Technical Reports Server (NTRS)

    Roussel-Dupre, R.

    1982-01-01

    The first order Boltzmann-Fokker-Planck equation is solved numerically to obtain diffusion and viscosity coefficients for a ternary gas mixture composed of electron, protons, and helium. The coefficients are tabulated for five He/H abundances ranging from 0.01 to 10 and for both He II and He III. Comparison with Burgers's thermal diffusion coefficients reveals a maximum difference of 9-10% for both He II and He III throughout the range of helium abundances considered. The viscosity coefficients are compared to those of Chapman and Cowling and show a maximum difference of only 5-6% for He II but 15-16% for He III. For the astrophysically important gas mixtures, it is concluded that the results of existing studies which employed Burgers's or Chapman and Cowling's coefficients will remain substantially unaltered.

  6. Compressible gas-solid mixture conservation laws simulations

    NASA Astrophysics Data System (ADS)

    Zeidan, D.; Slaouti, A.; Touma, R.

    2012-09-01

    Computations of gas-solid two-phase flow are carried out within the framework of mixture formulations. These computations are based on the Riemann problem for the resulting theoretical equations. The Riemann problem for the model equations is solved numerically using Godunov methods of centred-type. Numerical results are shown for carefully chosen test problems. The results show that both the model and the numerical methods provide very satisfactory solutions.

  7. Using gas-solid mixture conservation laws for volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Zeidan, D.; Touma, R.; Slaouti, A.

    2013-10-01

    This paper presents further validation of previous works [1, 2] on simulating fully hyperbolic and fully conservative gas-solid mixture PDEs. Such a system allows non-equilibrium processes between the two phase systems and facilitates explosive volcanic eruption investigations. Resolutions for this system are presented and compared with other numerical methods demonstrating the fundamental physical and numerical significances to the relative motion within volcanic eruptions.

  8. Predicting detection probabilities for gas mixtures over HSI backgrounds

    SciTech Connect

    Tardiff, Mark F.; Walsh, Stephen J.; Anderson, Kevin K.; Chilton, Lawrence

    2009-12-29

    Detecting and identifying weak gaseous plumes using thermal image data acquired by airborne detectors is an area of ongoing research. This contribution investigates the relative detectability of gas mixtures over different backgrounds and a range of plume temperatures that are warmer and cooler than the ground. The focus of this analysis to support mission planning. When the mission is intended to collect evidence of particular chemicals, the analysis presented is this report can be used to determine conditions under which useful data can be acquired. Initial analyses can be used to determine whether LWIR is useful for the anticipated gas, temperature, and background combination.

  9. 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.

  10. Modeling of non-thermal plasma in flammable gas mixtures

    NASA Astrophysics Data System (ADS)

    Napartovich, A. P.; Kochetov, I. V.; Leonov, S. B.

    2008-07-01

    An idea of using plasma-assisted methods of fuel ignition is based on non-equilibrium generation of chemically active species that speed up the combustion process. It is believed that gain in energy consumed for combustion acceleration by plasmas is due to the non-equilibrium nature of discharge plasma, which allows radicals to be produced in an above-equilibrium amount. Evidently, the size of the effect is strongly dependent on the initial temperature, pressure, and composition of the mixture. Of particular interest is comparison between thermal ignition of a fuel-air mixture and non-thermal plasma initiation of the combustion. Mechanisms of thermal ignition in various fuel-air mixtures have been studied for years, and a number of different mechanisms are known providing an agreement with experiments at various conditions. The problem is -- how to conform thermal chemistry approach to essentially non-equilibrium plasma description. The electric discharge produces much above-equilibrium amounts of chemically active species: atoms, radicals and ions. The point is that despite excess concentrations of a number of species, total concentration of these species is far below concentrations of the initial gas mixture. Therefore, rate coefficients for reactions of these discharge produced species with other gas mixture components are well known quantities controlled by the translational temperature, which can be calculated from the energy balance equation taking into account numerous processes initiated by plasma. A numerical model was developed combining traditional approach of thermal combustion chemistry with advanced description of the plasma kinetics based on solution of electron Boltzmann equation. This approach allows us to describe self-consistently strongly non-equilibrium electric discharge in chemically unstable (ignited) gas. Equations of pseudo-one-dimensional gas dynamics were solved in parallel with a system of thermal chemistry equations, kinetic equations for charged particles (electrons, positive and negative ions), and with the electric circuit equation. The electric circuit comprises power supply, ballast resistor connected in series with the discharge and capacity. Rate coefficients for electron-assisted reactions were calculated from solving the two-term spherical harmonic expansion of the Boltzmann equation. Such an approach allows us to describe influence of thermal chemistry reactions (burning) on the discharge characteristics. Results of comparison between the discharge and thermal ignition effects for mixtures of hydrogen or ethylene with dry air will be reported. Effects of acceleration of ignition by discharge plasma will be analyzed. In particular, the role of singlet oxygen produced effectively in the discharge in ignition speeding up will be discussed.

  11. Monte Carlo calculation of electron transport coefficients in counting gas mixtures I. Argon-methane mixtures

    NASA Astrophysics Data System (ADS)

    Fraser, G. W.; Mathieson, E.

    1986-07-01

    We describe a Monte Carlo simulation of electron transport in gas mixtures, under the influence of a uniform, nonionising electric field, E. Our calculations, in contrast with earlier studies of counting gases based on the Boltzmann transport equation, examine the anisotropic nature of electron diffusion. Independent estimators of the transverse and longitudinal diffusion coefficients F and DL are derived. For both pure argon and pure methane, predictions of the model are shown to be in good agreement with measurements of the electron mobility, μ, and of the ratios {D}/{μ}and{D L}/{μ} at field-to-pressure quotients 0.03 ⩽ {E}/{p} ⩽ 2.0 V cm-1Torr-1. Alternative methane cross sections are compared in detail. Finally, our calculations are extended to the mixtures A-10% CH 4. A-20% CH 4 and A-50% CH 4. This is the first part of an extensive study of electron drift and diffusion in common counting gas mixtures.

  12. High-Calorific Gas Mixtures Produced from Biomass

    NASA Astrophysics Data System (ADS)

    Kosov, Valentin; Kosov, Vladimir; Sinelschikov, Vladimir; Zaichenko, Victor

    Investigations in the field of processing of different types of biomass into high calorific gas fuel are carried out in the Joint Institute for High Temperatures of RAS. Design of technology for effective processing of low-grade solid fuel to gas mixtures which can be used as fuel for power plants is rather actual problem both in the view of natural resources conservation and in the view of the development of autonomous energy unit for thermal and electric power supply. The experimental data on quantity and composition of the gaseous products formed in the process of peat pyrolysis are presented at various operating parameters of the process. It is shown that as a result of peat pyrolysis and the subsequent cracking of emanating products at temperature 1,000 °C it is possible to receive 1.4 m3 of gas with specific caloricity 11.7 MJ/m3 per 1 kg of original raw material.

  13. Autoerotic accident by inhalation of propane-butane gas mixture.

    PubMed

    Jackowski, Christian; Rmhild, Wolfgang; Aebi, Beat; Bernhard, Werner; Krause, Dieter; Dirnhofer, Richard

    2005-12-01

    We present a case of an accidental autoerotic death involving the inhalation of a propane-butane gas mixture, also known as LPG (liquefied petroleum gas). A 19-year-old male was found dead in supine position in his bed in a residential accommodation one day after he was last seen alive. On a personal computer at the end of the bed, a pornographic movie was still running. On his left shoulder, an empty rubber balloon and on the bedside 2 empty "Kisag-Gas" cartridges were found. Toxicologic investigations revealed an intoxication with propane and butane, together with a recent consumption of cannabis. This case report compares the toxicologic findings with other recently published cases, and the theories of the toxic effects are discussed. PMID:16304471

  14. Laser beam characterization of the ATLAS RPC gas mixture

    NASA Astrophysics Data System (ADS)

    Chiodini, G.; Coluccia, M. R.; Gorini, E.; Grancagnolo, F.; Primavera, M.

    2007-10-01

    A measurement of the electrons drift velocity in C 2H 2F 4-based gas mixture has been performed and results have been compared with calculations. Primary ionization is induced in the gas via double photon ionization process by mean of a pulsed Nitrogen laser. The results of the drift velocity, obtained at room temperature and normal pressure, are presented as a function of the electric field strength. To perform the measurements we used a small sized RPC prototype with a 2 mm gas gap delimited by 2mm-thick linseed-oil-treated bakelite plates with resistivity of about 1.71×10Ω cm at 20°C.

  15. Understanding the response behavior of potentiometric gas sensors for non-equilibrium gas mixtures

    SciTech Connect

    Garzon, F. H.; Mukundan, R.; Brosha, E. L.

    2002-01-01

    Many applications of gas sensors require concentration measurements of reactive gases in mixtures that are out of thermodynamic equilibrium. These applications include: hydrogen and hydrocarbon fuel gas sensors operating in ambient air for explosion hazard detection, carbon monoxide detection in ambient air for health protection, combustion efficiency sensors for stoichiometry control, and nitric oxide sensors for air pollution monitoring. Many potentiometric and amperometric electrochemical sensor technologies have been developed for these applications. A class of the potentiometric sensors developed for gas mixtures are the non-Nerstian sensors. This presentation defines a categorization and theoretical analysis of three distinct electrochemical processes that can produce a non-Nernstian sensor response.

  16. Ternary gas mixtures for high-voltage industrial insulation

    NASA Astrophysics Data System (ADS)

    Pace, M. O.; Chan, C. C.; Christophorou, L. G.

    1981-10-01

    Gas dielectrics for insulating power apparatus, e.g., gas insulated transmission lines (GITL), were evaluated. Particular attention was given to mixtures using large proportions of an electron moderating gas (viz., N2, CHF3, or 1,1,1-C2H3F3) and smaller quantities of two electron attaching gases: SF6 and one fluorocarbon (e.g., c-C4F8). The proportions were sought at which the three gases function best as a team, moderating free electrons from higher to lower energies and there attaching them. Small amounts of the electron attaching additives can drastically raise the dielectric strength of the moderator. Certain combinations of SF6 and fluorocarbons do not produce the undesirable spark by products associated with either SF6 or fluorocarbons alone and also show improved negative polarity impulse breakdown characteristics over pure SF6. Small scale breakdown measurements were made of various ternary mixtures in the GITL geometry. It was found that nitrogen moderates electrons to extremely low energies, where SF6 attaches; the dipolar gases moderate to somewhat higher energies, where some fluorocarbons attach best.

  17. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

    Hunter, Scott R.; Christophorou, Loucas G.

    1990-01-01

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue of the combined physio-electric properties of the mixture components.

  18. Measurement of Absolute Xenon Density and Gas Injection Impact in Hall Thrusters

    NASA Astrophysics Data System (ADS)

    Vial, V.; Lazurenko, A.; Pagnon, D.; Bouchoule, A.

    2004-10-01

    This paper is focused on gas injection in Hall thrusters, from neutral gas simulation and experimental characterization to impacts on the thruster behavior. Optical methods have been employed to observe and to analyze the impact of the propellant injection on the density distribution in the channel of a SPT-100 type thruster and on its behavior while firing. The experimental data on the gas distribution obtained by density measurements are compared to codes predictions. These results allow to validate numerical assumptions such as the beamlet structure at the exit of the distributor or the atom-wall interaction. In a second step several injection modes have been tested on the thruster itself to examine the impact of the injection mode on the electric behavior and on the plume of the thruster.

  19. Asymptotic-preserving Boltzmann model equations for binary gas mixture

    NASA Astrophysics Data System (ADS)

    Liu, Sha; Liang, Yihua

    2016-02-01

    An improved system of Boltzmann model equations is developed for binary gas mixture. This system of model equations has a complete asymptotic preserving property that can strictly recover the Navier-Stokes equations in the continuum limit with the correct constitutive relations and the correct viscosity, thermal conduction, diffusion, and thermal diffusion coefficients. In this equation system, the self- and cross-collision terms in Boltzmann equations are replaced by single relaxation terms. In monocomponent case, this system of equations can be reduced to the commonly used Shakhov equation. The conservation property and the H theorem which are important for model equations are also satisfied by this system of model equations.

  20. Investigation of plasma-dust structures in He-Ar gas mixture

    SciTech Connect

    Maiorov, S. A.; Ramazanov, T. S.; Dzhumagulova, K. N.; Jumabekov, A. N.; Dosbolayev, M. K.

    2008-09-15

    The paper reports on the first experiments with plasma-dust formations in dc gas discharge plasma for a He-Ar mixture. It is shown that the choice of light and heavy gases for the mixture suppresses ion heating in electric field under the conventional conditions of experiments and results in a supersonic jet with high Mach numbers. Distribution functions for drifting ions in the gas mixture are calculated for various mixture concentrations, electric field strengths, and gas pressures.

  1. Superconducting cable cooling system by helium gas and a mixture of gas and liquid helium

    DOEpatents

    Dean, John W.

    1977-01-01

    Thermally contacting, oppositely streaming cryogenic fluid streams in the same enclosure in a closed cycle that changes from a cool high pressure helium gas to a cooler reduced pressure helium fluid comprised of a mixture of gas and boiling liquid so as to be near the same temperature but at different pressures respectively in go and return legs that are in thermal contact with each other and in thermal contact with a longitudinally extending superconducting transmission line enclosed in the same cable enclosure that insulates the line from the ambient at a temperature T.sub.1. By first circulating the fluid in a go leg from a refrigerator at one end of the line as a high pressure helium gas near the normal boiling temperature of helium; then circulating the gas through an expander at the other end of the line where the gas becomes a mixture of reduced pressure gas and boiling liquid at its boiling temperature; then by circulating the mixture in a return leg that is separated from but in thermal contact with the gas in the go leg and in the same enclosure therewith; and finally returning the resulting low pressure gas to the refrigerator for compression into a high pressure gas at T.sub.2 is a closed cycle, where T.sub.1 >T.sub.2, the temperature distribution is such that the line temperature is nearly constant along its length from the refrigerator to the expander due to the boiling of the liquid in the mixture. A heat exchanger between the go and return lines removes the gas from the liquid in the return leg while cooling the go leg.

  2. 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.

  3. Xenon Additives Detection in Helium Micro-Plasma Gas Analytical Sensor

    NASA Astrophysics Data System (ADS)

    Tsyganov, Alexander; Kudryavtsev, Anatoliy; Mustafaev, Alexander

    2012-10-01

    Electron energy spectra of Xe atoms at He filled micro-plasma afterglow gas analyzer were observed using Collisional Electron Spectroscopy (CES) method [1]. According to CES, diffusion path confinement for characteristic electrons makes it possible to measure electrons energy distribution function (EEDF) at a high (up to atmospheric) gas pressure. Simple geometry micro-plasma CES sensor consists of two plane parallel electrodes detector and microprocessor-based acquisition system providing current-voltage curve measurement in the afterglow of the plasma discharge. Electron energy spectra are deduced as 2-nd derivative of the measured current-voltage curve to select characteristic peaks of the species to be detected. Said derivatives were obtained by the smoothing-differentiating procedure using spline least-squares approximation of a current-voltage curve. Experimental results on CES electron energy spectra at 10-40 Torr in pure He and in admixture with 0.3% Xe are discussed. It demonstrates a prototype of the new miniature micro-plasma sensors for industry, safety and healthcare applications. [1]. A.A.Kudryavtsev, A.B.Tsyganov. US Patent 7,309,992. Gas analysis method and ionization detector for carrying out said method, issued December 18, 2007.

  4. Chemical Discrimination in Turbulent Gas Mixtures with MOX Sensors Validated by Gas Chromatography-Mass Spectrometry

    PubMed Central

    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

  5. The Search for Dark Matter with the XENON100 Experiment

    SciTech Connect

    Aprile, Elena

    2008-11-23

    The XENON Dark Matter Experiment aims at the direct detection of dark matter Weakly Interacting Massive Particles (WIMPs) with dual phase (liquid/gas) xenon time projection chambers (XeTPCs). Following the successful performance of the XENON10 detector, which has shown in 2007 the best sensitivity to spin-independent coupling of WIMPs to matter, we have designed and completed the construction of a new TPC with an active LXe shield, containing a total of 170 kg of xenon. The detector is currently undergoing final commissioning at the Gran Sasso Underground Laboratory. I will review the XENON10 results and present the status of the XENON100 experiment.

  6. A fluidic device for measuring constituent masses of a flowing binary gas mixture

    NASA Technical Reports Server (NTRS)

    Prokopius, P. R.

    1973-01-01

    A continuous reading mass flow device was developed to measure the component flow of a binary gas mixture. The basic components of the device are a fluidic humidity sensor and a specially designed flow calorimeter. These components provide readings of gas mixture ratio, mixture heat capacity, heat dissipated by the calorimeter and the gas temperature rise across the calorimeter. These parameter values, applied in the general definitions of specific heat capacity and the heat capacity of a gas mixture, produce calculated component flow rates of the mixture being metered. A test program was conducted to evaluate both the steady state and dynamic performance of the device.

  7. Operation of gas electron multiplier (GEM) with propane gas at low pressure and comparison with tissue-equivalent gas mixtures

    NASA Astrophysics Data System (ADS)

    De Nardo, L.; Farahmand, M.

    2016-05-01

    A Tissue-Equivalent Proportional Counter (TEPC), based on a single GEM foil of standard geometry, has been tested with pure propane gas at low pressure, in order to simulate a tissue site of about 1 μm equivalent size. In this work, the performance of GEM with propane gas at a pressure of 21 and 28 kPa will be presented. The effective gas gain was measured in various conditions using a 244Cm alpha source. The dependence of effective gain on the electric field strength along the GEM channel and in the drift and induction region was investigated. A maximum effective gain of about 5×103 has been reached. Results obtained in pure propane gas are compared with gas gain measurements in gas mixtures commonly employed in microdosimetry, that is propane and methane based Tissue-Equivalent gas mixtures.

  8. A study of the xenon effect in type-II clathrate hydrate synthesis; Commencing with hydrogen, argon and xenon uptake into a propane clathrate hydrate

    NASA Astrophysics Data System (ADS)

    Abbondondola, Joanne Angela

    It has been proposed that clathrate hydrates can be a possible storage medium for alternative fuels, such as hydrogen. The type-II propane gas hydrate is a viable choice because there are twice as many small cages as large cages and the small cavities are available for hydrogen storage. However, propane hydrate formation is a kinetically slow process which makes it commercially unattractive. Our objectives were twofold; (1) to quantify hydrogen, argon and xenon sorption into a preformed type-II propane hydrate at near-ambient conditions and (2) to investigate the effect of xenon on the rate of type-II propane hydrate formation. The propane hydrate is synthesized from 250 mum ice grains, and is estimated to have a porosity of 65 %. Hydrogen is rapidly absorbed by the hydrate sample and approaches the equilibrium vapor pressure in an hour before a very slow residual absorption process ensues. For an initial hydrogen pressure of 1.5 MPa, about 4.5 % of the available 512 cages are occupied by hydrogen after one hour, and 4.9 % after 18 hours. In contrast, for both argon and xenon significantly more gas is absorbed by the hydrate, but at a much slower rate: about 5% as fast for xenon and 1% as fast for argon. We conclude that hydrogen readily diffuses through the propane hydrate microcrystal structure, while argon and xenon are probably absorbed by growing new double hydrate while consuming the propane hydrate. Thus, although considerably higher pressures would be required to store significant quantities of hydrogen in propane hydrate, it appears that the crystal can be loaded and emptied in relatively short amounts of time. Experimental results show that propane is incorporated into clathrate hydrate cages more rapidly using propane-xenon mixtures than for pure propane gas. For a 0.92 xenon: propane mix, 60% of the theoretical yield of propane enclathration is achieved in 20 minutes, versus several days for pure propane. It appears that xenon serves to nucleate the dodecahedral 512 cages, and that the presence of propane results in type-II structure growth rather than the native xenon type-I structure. The type-II xenon-propane structure is more thermodynamically stable than either pure hydrate.

  9. Application of Two Phase (Liquid/Gas) Xenon Gamma-Camera for the Detection of Special Nuclear Material and PET Medical Imaging

    SciTech Connect

    McKinsey, Daniel Nicholas

    2013-08-27

    The McKinsey group at Yale has been awarded a grant from DTRA for the building of a Liquid Xenon Gamma Ray Color Camera (LXe-GRCC), which combines state-of-the-art detection of LXe scintillation light and time projection chamber (TPC) charge readout. The DTRA application requires a movable detector and hence only a single phase (liquid) xenon detector can be considered in this case. We propose to extend the DTRA project to applications that allow a two phase (liquid/gas) xenon TPC. This entails additional (yet minimal) hardware and extension of the research effort funded by DTRA. The two phase detector will have better energy and angular resolution. Such detectors will be useful for PET medical imaging and detection of special nuclear material in stationary applications (e.g. port of entry). The expertise of the UConn group in gas phase TPCs will enhance the capabilities of the Yale group and the synergy between the two groups will be very beneficial for this research project as well as the education and research projects of the two universities. The LXe technology to be used in this project has matured rapidly over the past few years, developed for use in detectors for nuclear physics and astrophysics. This technology may now be applied in a straightforward way to the imaging of gamma rays. According to detailed Monte Carlo simulations recently performed at Yale University, energy resolution of 1% and angular resolution of 3 degrees may be obtained for 1.0 MeV gamma rays, using existing technology. With further research and development, energy resolution of 0.5% and angular resolution of 1.3 degrees will be possible at 1.0 MeV. Because liquid xenon is a high density, high Z material, it is highly efficient for scattering and capturing gamma rays. In addition, this technology scales elegantly to large detector areas, with several square meter apertures possible. The Yale research group is highly experienced in the development and use of noble liquid detectors for astrophysics, most recently in the XENON10 experiment. The existing facilities at Yale are fully adequate for the completion of this project. The facilities of the UConn group at the LNS at Avery Point include a (clean) lab for detector development and this group recently delivered an Optical Readout TPC (O-TPC) for research in Nuclear Astrophysics at the TUNL in Duke University. The machine shop at UConn will be used (free of charge) for producing the extra hardware needed for this project including grids and frames.

  10. Method for the simultaneous preparation of Radon-211, Xenon-125, Xenon-123, Astatine-211, Iodine-125 and Iodine-123

    DOEpatents

    Mirzadeh, Saed; Lambrecht, Richard M.

    1987-01-01

    A method for simultaneously preparing Radon-211, Astatine-211, Xenon-125, Xenon-123, Iodine-125 and Iodine-123 in a process that includes irradiating a fertile metal material then using a one-step chemical procedure to collect a first mixture of about equal amounts of Radon-211 and Xenon-125, and a separate second mixture of about equal amounts of Iodine-123 and Astatine-211.

  11. Magnetic resonance imaging of convection in laser-polarized xenon

    NASA Technical Reports Server (NTRS)

    Mair, R. W.; Tseng, C. H.; Wong, G. P.; Cory, D. G.; Walsworth, R. L.

    2000-01-01

    We demonstrate nuclear magnetic resonance (NMR) imaging of the flow and diffusion of laser-polarized xenon (129Xe) gas undergoing convection above evaporating laser-polarized liquid xenon. The large xenon NMR signal provided by the laser-polarization technique allows more rapid imaging than one can achieve with thermally polarized gas-liquid systems, permitting shorter time-scale events such as rapid gas flow and gas-liquid dynamics to be observed. Two-dimensional velocity-encoded imaging shows convective gas flow above the evaporating liquid xenon, and also permits the measurement of enhanced gas diffusion near regions of large velocity variation.

  12. Process for testing a xenon gas feed system of a hollow cathode assembly

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J. (Inventor); Verhey, Timothy R. R. (Inventor); Soulas, George C. (Inventor)

    2004-01-01

    The design and manufacturing processes for Hollow Cathode Assemblies (HCA's) that operate over a broad range of emission currents up to 30 Amperes, at low potentials, with lifetimes in excess of 17,500 hours. The processes include contamination control procedures which cover hollow cathode component cleaning procedures, gas feed system designs and specifications, and hollow cathode activation and operating procedures to thereby produce cathode assemblies that have demonstrated stable and repeatable operating conditions, for both the discharge current and voltage. The HCA of this invention provides lifetimes of greater than 10,000 hours, and expected lifetimes of greater than 17,500 hours, whereas the present state-of-the-art is less than 500 hours at emission currents in excess of 1 Ampere. Stable operation is provided over a large range of operating emission currents, up to a 6:1 ratio, and this HCA can emit electron currents of up to 30 Amperes in magnitude to an external anode that simulates the current drawn to a space plasma, at voltages of less than 20 Volts.

  13. Solid Xenon Project

    NASA Astrophysics Data System (ADS)

    Balakishiyeva, Durdana N.; Mahapatra, Rupak; Saab, Tarek; Yoo, Jonghee

    2010-08-01

    Crystals like Germanium and Silicon need to be grown in specialized facilities which is time and money costly. It takes many runs to test the detector once it's manufactured and mishaps are very probable. It is of a great challenge to grow big germanium crystals and that's why stacking them up in a tower is the only way at the moment to increase testing mass. Liquid Noble gas experiments experiencing contamination problems, their predicted energy resolution at 10 keV and lower energy range is not as good as predicted. Every experiment is targeting one specific purpose, looking for one thing. Why not to design an experiment that is diverse and build a detector that can search for Dark Matter, Solar Axions, Neutrinoless Double Beta decay, etc. Solid Xenon detector is such detector. We designed a simple Xenon crystal growing chamber that was put together at Fermi National Accelerator Laboratory. The first phase of this experiment was to demonstrate that a good, crack free Xenon crystal can be grown (regardless of many failed attempts by various groups) and our first goal, 1 kg crystal, was successful.

  14. Solid Xenon Project

    SciTech Connect

    Balakishiyeva, Durdana N.; Saab, Tarek; Mahapatra, Rupak; Yoo, Jonghee

    2010-08-30

    Crystals like Germanium and Silicon need to be grown in specialized facilities which is time and money costly. It takes many runs to test the detector once it's manufactured and mishaps are very probable. It is of a great challenge to grow big germanium crystals and that's why stacking them up in a tower is the only way at the moment to increase testing mass. Liquid Noble gas experiments experiencing contamination problems, their predicted energy resolution at 10 keV and lower energy range is not as good as predicted. Every experiment is targeting one specific purpose, looking for one thing. Why not to design an experiment that is diverse and build a detector that can search for Dark Matter, Solar Axions, Neutrinoless Double Beta decay, etc. Solid Xenon detector is such detector. We designed a simple Xenon crystal growing chamber that was put together at Fermi National Accelerator Laboratory. The first phase of this experiment was to demonstrate that a good, crack free Xenon crystal can be grown (regardless of many failed attempts by various groups) and our first goal, 1 kg crystal, was successful.

  15. Smoothed particle hydrodynamics simulations of gas and dust mixtures

    NASA Astrophysics Data System (ADS)

    Booth, R. A.; Sijacki, D.; Clarke, C. J.

    2015-10-01

    We present a `two-fluid' implementation of dust in smoothed particle hydrodynamics (SPH) in the test particle limit. The scheme is able to handle both short and long stopping times and reproduces the short friction time limit, which is not properly handled in other implementations. We apply novel tests to verify its accuracy and limitations, including multidimensional tests that have not been previously applied to the drag-coupled dust problem and which are particularly relevant to self-gravitating protoplanetary discs. Our tests demonstrate several key requirements for accurate simulations of gas-dust mixtures. First, in standard SPH particle jitter can degrade the dust solution, even when the gas density is well reproduced. The use of integral gradients, a Wendland kernel and a large number of neighbours can control this, albeit at a greater computational cost. Secondly, when it is necessary to limit the artificial viscosity we recommend using the Cullen & Dehnen switch, since the alternative, using α ˜ 0.1, can generate a large velocity noise up to σv ≲ 0.3cs in the dust particles. Thirdly, we find that an accurate dust density estimate requires >400 neighbours, since, unlike the gas, the dust particles do not feel regularization forces. This density noise applies to all particle-based two-fluid implementations of dust, irrespective of the hydro solver and could lead to numerically induced fragmentation. Although our tests show accurate dusty gas simulations are possible, care must be taken to minimize the contribution from numerical noise.

  16. 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.

  17. Buffer-gas influence on multiphoton absorption and dissociation in different gas mixtures

    NASA Astrophysics Data System (ADS)

    Nikolić, J. D.; Rabasović, M. D.; Markushev, D. D.; Jovanović-Kurepa, J.

    2008-03-01

    Buffer-gas influence on the multiphoton absorption and dissociation in different mixtures was investigated using the simple method based on the empirical and theoretical vibrational energy distribution, generalized coupled two-level model and photoacoustic cell especially designed for low pressures studies. Energy transfer efficiency was analyzed by means of pulsed photoacoustic spectroscopy technique. Collisional effects of buffer-gas (Ar) pressure are introduced to enhance the absorption and relaxation characteristics of irradiated absorbing molecules (SF 6). Functional behavior of mean number of absorbed photons per molecule < n> total and a dependence on buffer-gas pressure ( pbuff) which enables us to confirm or predict some physical and chemical processes are presented. Limitation of proposed model was analyzed depending on both gas pressure and laser fluence. Results are compared with other previously obtained by the same experimental technique but for different absorber and different molecular buffer-gas.

  18. 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.

  19. 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.

  20. 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.

  1. Argon-Hydrogen Shielding Gas Mixtures for Activating Flux-Assisted Gas Tungsten Arc Welding

    NASA Astrophysics Data System (ADS)

    Huang, Her-Yueh

    2010-11-01

    Using activating flux for gas tungsten arc welding (GTAW) to improve penetration capability is a well-established technique. Argon is an inert gas and the one most widely used as a shielding gas for GTAW. For the most austenitic stainless steels, pure argon does not provide adequate weld penetration. Argon-hydrogen mixtures give a more even heat input to the workpiece, increasing the arc voltage, which tends to increase the volume of molten material in the weld pool as well as the weld depth-to-width ratio. Great interest has been shown in the interaction between activating flux and the hydrogen concentration in an argon-based shielding gas. In this study, the weld morphology, the arc profile, the retained delta ferrite content, the angular distortion, and the microstructures were examined. The application of an activating flux combining argon and hydrogen for GTAW is important in the industry. The results of this study are presented here.

  2. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

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

    1988-04-27

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue if the combines physio-electric properties of the mixture components. 9 figs.

  3. High-frequency sound wave propagation in binary gas mixtures flowing through microchannels

    NASA Astrophysics Data System (ADS)

    Bisi, M.; Lorenzani, S.

    2016-05-01

    The propagation of high-frequency sound waves in binary gas mixtures flowing through microchannels is investigated by using the linearized Boltzmann equation based on a Bhatnagar-Gross-Krook (BGK)-type approach and diffuse reflection boundary conditions. The results presented refer to mixtures whose constituents have comparable molecular mass (like Ne-Ar) as well as to disparate-mass gas mixtures (composed of very heavy plus very light molecules, like He-Xe). The sound wave propagation model considered in the present paper allows to analyze the precise nature of the forced-sound modes excited in different gas mixtures.

  4. Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

    SciTech Connect

    Aines, Roger D

    2015-03-31

    A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

  5. The intense VUV narrow band emission from an inert gas mixture discharge

    NASA Astrophysics Data System (ADS)

    Gerasimov, G.; Hallin, R.; Krylov, B.; Treshchalov, A.; Morozov, A.; Lissovski, A.; Zwereva, G.; Arnesen, A.

    2006-05-01

    Theoretical and experimental studies of low temperature plasmas of inert gas mixtures show a very high efficiency for energy transfer from broad vacuum ultravio let (VUV) continua to narrow spectra. The process of energy transfer can not be explained as an ordinary particle collision mechanism. Narrow band light amplification in plasmas of inert gas mixtures is discussed as a possible process of energy transfer.

  6. Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

    DOEpatents

    Aines, Roger D.

    2013-03-12

    A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

  7. Metastable sound speed in gas-liquid mixtures

    NASA Technical Reports Server (NTRS)

    Bursik, J. W.; Hall, R. M.

    1979-01-01

    A new method of calculating speed of sound for two-phase flow is presented. The new equation assumes no phase change during the propagation of an acoustic disturbance and assumes that only the total entropy of the mixture remains constant during the process. The new equation predicts single-phase values for the speed of sound in the limit of all gas or all liquid and agrees with available two-phase, air-water sound speed data. Other expressions used in the two-phase flow literature for calculating two-phase, metastable sound speed are reviewed and discussed. Comparisons are made between the new expression and several of the previous expressions -- most notably a triply isentropic equation as used, a triply isentropic equation as used, among others, by Karplus and by Wallis. Appropriate differences are pointed out and a thermodynamic criterion is derived which must be satisfied in order for the triply isentropic expression to be thermodynamically consistent. This criterion is not satisfied for the cases examined, which included two-phase nitrogen, air-water, two-phase parahydrogen, and steam-water. Consequently, the new equation derived is found to be superior to the other equations reviewed.

  8. Flammability of gas mixtures. Part 1: fire potential.

    PubMed

    Schröder, Volkmar; Molnarne, Maria

    2005-05-20

    International and European dangerous substances and dangerous goods regulations refer to the standard ISO 10156 (1996). This standard includes a test method and a calculation procedure for the determination of the flammability of gases and gas mixtures in air. The substance indices for the calculation, the so called "Tci values", which characterise the fire potential, are provided as well. These ISO Tci values are derived from explosion diagrams of older literature sources which do not take into account the test method and the test apparatus. However, since the explosion limits are influenced by apparatus parameters, the Tci values and lower explosion limits, given by the ISO tables, are inconsistent with those measured according to the test method of the same standard. In consequence, applying the ISO Tci values can result in wrong classifications. In this paper internationally accepted explosion limit test methods were evaluated and Tci values were derived from explosion diagrams. Therefore, an "open vessel" method with flame propagation criterion was favoured. These values were compared with the Tci values listed in ISO 10156. In most cases, significant deviations were found. A detailed study about the influence of inert gases on flammability is the objective of Part 2. PMID:15885404

  9. Dissipation process of binary gas mixtures in thermally relativistic flow

    NASA Astrophysics Data System (ADS)

    Yano, Ryosuke

    2016-04-01

    In this paper, dissipation process of binary gas mixtures in thermally relativistic flows is discussed with focus on characteristics of diffusion flux. As an analytical object, we consider the relativistic rarefied-shock layer around a triangular prism. Numerical results for the diffusion flux are compared with the Navier–Stokes–Fourier (NSF) order approximation of the diffusion flux, which is calculated using the diffusion and thermal-diffusion coefficients by Kox et al (1976 Physica A 84 165–74). In the case of uniform flow with small Lorentz contraction, the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is roughly approximated by the NSF order approximation inside the shock wave, whereas the diffusion flux in the vicinity of a wall is markedly different from the NSF order approximation. The magnitude of the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is similar to that of the NSF order approximation inside the shock wave, unlike the pressure deviator, dynamic pressure and heat flux, even when the Lorentz contraction in the uniform flow becomes large, because the diffusion flux does not depend on the generic Knudsen number from its definition in Eckart’s frame. Finally, the author concludes that for accuracy diffusion flux must be calculated using the particle four-flow and averaged four velocity, which are formulated using the four velocity defined by each species of hard spherical particles.

  10. Response of tomato plants to simulated landfill gas mixtures

    SciTech Connect

    Arthur, J.J.; Leone, I.A.; Flower, F.B.

    1985-01-01

    The roots of tomato plants were fumigated with simulated refuse-generated gas mixtures at levels of methane (CH/sub 4/), carbon dioxide (CO/sub 2/), and oxygen (O/sub 2/) previously measured in the atmospheres of landfill cover soils associated with poor growth or death of plants. A concentration of 18% CO/sub 2/ or greater, exceeded in almost 30% of thirty-two landfills examined throughout the US, caused reduced growth and visible symptoms on tomato after 1 wk, regardless of O/sub 2/ level. Doubling the CO/sub 2/ level to that encountered in a typical local site (Edgeboro Landfill) resulted in more severe symptom development and the subsequent death of plants. Methane, in concentrations of 20% and above, found in more than 25% of the landfills visited, while not observed to be toxic per se; was associated with drastic O/sub 2/ depletion in the soil atmosphere, which activity was believed to be the cause of the plant decline.

  11. Gas-phase detonation propagation in mixture composition gradients.

    PubMed

    Kessler, D A; Gamezo, V N; Oran, E S

    2012-02-13

    The propagation of detonations through several fuel-air mixtures with spatially varying fuel concentrations is examined numerically. The detonations propagate through two-dimensional channels, inside of which the gradient of mixture composition is oriented normal to the direction of propagation. The simulations are performed using a two-component, single-step reaction model calibrated so that one-dimensional detonation properties of model low- and high-activation-energy mixtures are similar to those observed in a typical hydrocarbon-air mixture. In the low-activation-energy mixture, the reaction zone structure is complex, consisting of curved fuel-lean and fuel-rich detonations near the line of stoichiometry that transition to decoupled shocks and turbulent deflagrations near the channel walls where the mixture is extremely fuel-lean or fuel-rich. Reactants that are not consumed by the leading detonation combine downstream and burn in a diffusion flame. Detonation cells produced by the unstable reaction front vary in size across the channel, growing larger away from the line of stoichiometry. As the size of the channel decreases relative to the size of a detonation cell, the effect of the mixture composition gradient is lessened and cells of similar sizes form. In the high-activation-energy mixture, detonations propagate more slowly as the magnitude of the mixture composition gradient is increased and can be quenched in a large enough gradient. PMID:22213660

  12. Two-dimensional simulation of the development of an inhomogeneous volume discharge in a Ne/Xe/HCl gas mixture

    SciTech Connect

    Bychkov, Yu. I. Yampolskaya, S. A.; Yastremskii, A. G.

    2013-05-15

    The kinetic processes accompanying plasma column formation in an inhomogeneous discharge in a Ne/Xe/HCl gas mixture at a pressure of 4 atm were investigated by using a two-dimensional model. Two cathode spots spaced by 0.7 cm were initiated by distorting the cathode surface at local points, which resulted in an increase in the field strength in the cathode region. Three regimes differing in the charging voltage, electric circuit inductance, and electric field strength at the local cathode points were considered. The spatiotemporal distributions of the discharge current; the electron density; and the densities of excited xenon atoms, HCl(v = 0) molecules in the ground state, and HCl(v > 0) molecules in vibrational levels were calculated. The development of the discharge with increasing the electron density from 10{sup 4} to 10{sup 16} cm{sup -3} was analyzed, and three characteristic stages in the evolution of the current distribution were demonstrated. The width of the plasma column was found to depend on the energy deposited in the discharge. The width of the plasma column was found to decrease in inverse proportion to the deposited energy due to spatiotemporal variations in the rates of electron production and loss. The calculated dependences of the cross-sectional area of the plasma column on the energy deposited in the discharge agree with the experimental results.

  13. [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

  14. 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.

  15. 30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-6 Exemption of small low pressure gas cylinders... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. 75.1106-6 Section 75.1106-6 Mineral Resources...

  16. 30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-6 Exemption of small low pressure gas cylinders... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. 75.1106-6 Section 75.1106-6 Mineral Resources...

  17. 30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-6 Exemption of small low pressure gas cylinders... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. 75.1106-6 Section 75.1106-6 Mineral Resources...

  18. 30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-6 Exemption of small low pressure gas cylinders... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. 75.1106-6 Section 75.1106-6 Mineral Resources...

  19. 30 CFR 75.1106-6 - Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1106-6 Exemption of small low pressure gas cylinders... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Exemption of small low pressure gas cylinders containing nonflammable or nonexplosive gas mixtures. 75.1106-6 Section 75.1106-6 Mineral Resources...

  20. Optimal detectors for WIMP and 0 ν ββ searches: Identical high-pressure xenon gas TPCs?

    NASA Astrophysics Data System (ADS)

    Nygren, David

    2007-11-01

    A time projection chamber (TPC) filled with high-pressure gaseous xenon (HPXe)—instead of liquid xenon (LXe)—appears likely to offer both superior energy resolution for the 0-ν ββ decay search in 136Xe and superior γ-background rejection in the search for WIMPs. An augmentation to maximize the primary scintillation detection efficiency of the 0-ν ββ decay detector design will realize an optimum design for both purposes. In this scenario an attractive synergy exists: two identical HPXe TPCs differing only in isotopic content will provide significantly more robust evidence for the existence of either signal if present. A simple analysis of important factors that limit energy resolution leads to the conclusion that the optimal design for either next-generation search at the few hundred kg level is the same HPXe-based TPC. A careful measurement of the scintillation and ionization responses of HPXe to nuclear and electronic recoils is needed to test the claim of HPXe superiority to LXe for the combined goals.

  1. Data set from chemical sensor array exposed to turbulent gas mixtures

    PubMed Central

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

    2015-01-01

    A chemical detection platform composed of 8 chemo-resistive gas sensors was exposed to turbulent gas mixtures generated naturally in a wind tunnel. The acquired time series of the sensors are provided. The experimental setup was designed to test gas sensors in realistic environments. Traditionally, chemical detection systems based on chemo-resistive sensors include a gas chamber to control the sample air flow and minimize turbulence. Instead, we utilized a wind tunnel with two independent gas sources that generate two gas plumes. The plumes get naturally mixed along a turbulent flow and reproduce the gas concentration fluctuations observed in natural environments. Hence, the gas sensors can capture the spatio-temporal information contained in the gas plumes. The sensor array was exposed to binary mixtures of ethylene with either methane or carbon monoxide. Volatiles were released at four different rates to induce different concentration levels in the vicinity of the sensor array. Each configuration was repeated 6 times, for a total of 180 measurements. The data is related to “Chemical Discrimination in Turbulent Gas Mixtures with MOX Sensors Validated by Gas Chromatography-Mass Spectrometry”, by Fonollosa et al. [1]. The dataset can be accessed publicly at the UCI repository upon citation of [1]: http://archive.ics.uci.edu/ml/datasets/Gas+senso+rarray+exposed+to+turbulent+gas+mixtures. PMID:26217747

  2. Data set from chemical sensor array exposed to turbulent gas mixtures.

    PubMed

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

    2015-06-01

    A chemical detection platform composed of 8 chemo-resistive gas sensors was exposed to turbulent gas mixtures generated naturally in a wind tunnel. The acquired time series of the sensors are provided. The experimental setup was designed to test gas sensors in realistic environments. Traditionally, chemical detection systems based on chemo-resistive sensors include a gas chamber to control the sample air flow and minimize turbulence. Instead, we utilized a wind tunnel with two independent gas sources that generate two gas plumes. The plumes get naturally mixed along a turbulent flow and reproduce the gas concentration fluctuations observed in natural environments. Hence, the gas sensors can capture the spatio-temporal information contained in the gas plumes. The sensor array was exposed to binary mixtures of ethylene with either methane or carbon monoxide. Volatiles were released at four different rates to induce different concentration levels in the vicinity of the sensor array. Each configuration was repeated 6 times, for a total of 180 measurements. The data is related to "Chemical Discrimination in Turbulent Gas Mixtures with MOX Sensors Validated by Gas Chromatography-Mass Spectrometry", by Fonollosa et al. [1]. The dataset can be accessed publicly at the UCI repository upon citation of [1]: http://archive.ics.uci.edu/ml/datasets/Gas+senso+rarray+exposed+to+turbulent+gas+mixtures. PMID:26217747

  3. Falling microbead counter-flow process for separating gas mixtures

    SciTech Connect

    Hornbostel, Marc D.; Krishnan, Gopala N.; Sanjurjo, Angel

    2015-10-27

    A method and reactor for removing a component from a gas stream is provided. In one embodiment, the method includes providing the gas stream containing the component that is to be removed and adsorbing the component out of the gas stream as the gas stream rises via microbeads of a sorbent falling down an adsorber section of a reactor.

  4. Falling microbead counter-flow process for separating gas mixtures

    SciTech Connect

    Hornbostel, Marc D.; Krishnan, Gopala N.; Sanjurjo, Angel

    2015-07-07

    A method and reactor for removing a component from a gas stream is provided. In one embodiment, the method includes providing the gas stream containing the component that is to be removed and adsorbing the component out of the gas stream as the gas stream rises via microbeads of a sorbent falling down an adsorber section of a reactor.

  5. Process for the separation of components from gas mixtures

    DOEpatents

    Merriman, J.R.; Pashley, J.H.; Stephenson, M.J.; Dunthorn, D.I.

    1973-10-01

    A process for the removal, from gaseous mixtures of a desired component selected from oxygen, iodine, methyl iodide, and lower oxides of carbon, nitrogen, and sulfur is described. The gaseous mixture is contacted with a liquid fluorocarbon in an absorption zone maintained at superatmospheric pressure to preferentially absorb the desired component in the fluorocarbon. Unabsorbed constituents of the gaseous mixture are withdrawn from the absorption zone. Liquid fluorocarbon enriched in the desired component is withdrawn separately from the zone, following which the desired component is recovered from the fluorocarbon absorbent. (Official Gazette)

  6. 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

  7. Viscosity and thermal conductivity of moderately dense gas mixtures.

    NASA Technical Reports Server (NTRS)

    Wakeham, W. A.; Kestin, J.; Mason, E. A.; Sandler, S. I.

    1972-01-01

    Derivation of a simple, semitheoretical expression for the initial density dependence of the viscosity and thermal conductivity of gaseous mixtures in terms of the appropriate properties of the pure components and of their interaction quantities. The derivation is based on Enskog's theory of dense gases and yields an equation in which the composition dependence of the linear factor in the density expansion is explicit. The interaction quantities are directly related to those of the mixture extrapolated to zero density and to a universal function valid for all gases. The reliability of the formulation is assessed with respect to the viscosity of several binary mixtures. It is found that the calculated viscosities of binary mixtures agree with the experimental data with a precision which is comparable to that of the most precise measurements.

  8. 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...

  9. Xenon and Other Volatile Anesthetics Change Domain Structure in Model Lipid Raft Membranes

    PubMed Central

    Weinrich, Michael; Worcester, David L.

    2014-01-01

    Inhalation anesthetics have been in clinical use for over 160 years, but the molecular mechanisms of action continue to be investigated. Direct interactions with ion channels received much attention after it was found that anesthetics do not change the structure of homogeneous model membranes. However, it was recently found that halothane, a prototypical anesthetic, changes domain structure of a binary lipid membrane. The noble gas xenon is an excellent anesthetic and provides a pivotal test of the generality of this finding, extended to ternary lipid raft mixtures. We report that xenon and conventional anesthetics change the domain equilibrium in two canonical ternary lipid raft mixtures. These findings demonstrate a membrane-mediated mechanism whereby inhalation anesthetics can affect the lipid environment of trans-membrane proteins. PMID:24299622

  10. Vibrational relaxation of acetylene and acetylene--rare-gas mixtures

    SciTech Connect

    Haeger, J.; Krieger, W.; Rueegg, T.; Walther, H.

    1980-04-15

    Vibrational relaxation of acetylene (C/sub 2/H/sub 2/) and acetylene--rare-gas mixtures has been investigated using laser-induced fluorescence. Time-dependent fluorescence signals from the vibrational modes ..nu../sub 2/ and ..nu../sub 5/ have been recorded, following excitation of ..nu../sub 3/ and (..nu../sub 2/+..nu../sub 4/+..nu../sub 5/) at 3300 cm/sup -1/ with pulses of a tunable optical parametric oscillator. The activation rate of ..nu../sub 2/ and ..nu../sub 5/ were estimated to be >880 ms/sup -1/ Torr/sup -1/ and >330 ms/sup -1/ Torr/sup -1/, respectively. The following V-T/R relaxation rates have been obtained from the decay of the ..nu../sub 5/ fluorescence signal: (12.7 +- 1.1) ms/sup -1/ Torr/sup -1/ for C/sub 2/H/sub 2/ as collision partner, (0.46 +- 0.05) ms/sup -1/ Torr/sup -1/ for Ne, (0.66 +- 0.06) ms/sup -1/ Torr/sup -1/ for Ar, (0.67 +- 0.04) ms/sup -1/ Torr/sup -1/ for Kr, and (0.57 +- 0.04) ms/sup -1/ Torr/sup -1/ for Xe. Surprisingly small V--V deactivation rates of the CC stretching vibration ..nu../sub 2/ have been measured. These are (21.3 +- 1.0) ms/sup -1/ Torr/sup -1/ for C/sub 2/H/sub 2/ collisions, (0.63 +- 0.06) ms/sup -1/ Torr/sup -1/ for Ne, (0.78 +- 0.08) ms/sup -1/ Torr/sup -1/ for Ar, (0.93 +- 0.09) ms/sup -1/ Torr/sup -1/ for Kr, and (0.77 +- 0.09) ms/sup -1/ Torr/sup -1/ for Xe. Acetylene relaxation mechanisms compatible with these rates are considered.

  11. 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.

  12. Excitation of laser transitions in parametallic gas mixtures using reaction products from nuclear reactions

    SciTech Connect

    Dmitriev, A.B.; Il'yashenko, V.S.; Mis'kevich, A.I.; Salamakha, B.S.

    1982-11-01

    Luminescence is studied at high pressure in parametallic gas mixtures excited by products from neutron nuclear reactions. The use of /sup 3/He--Cd, /sup 3/He--Hg, and /sup 3/He--Cs mixtures as active laser media pumped by nuclear reactions is considered. Quasicontinuous lasing in a /sup 3/He--Cd mixture excited by a stream of neutrons is reported.

  13. 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

  14. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, R.J.; Basel, R.A.

    1996-03-12

    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. 4 figs.

  15. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, Roswell J.; Basel, Richard A.

    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.

  16. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... mixture of solar energy (including wind, tide, and other intermittent sources) and petroleum or natural gas, where: (1) Solar energy will account for at least 20 percent of the total annual Btu heat input... 10 Energy 4 2010-01-01 2010-01-01 false Permanent exemption for certain fuel mixtures...

  17. 10 CFR 503.38 - Permanent exemption for certain fuel mixtures containing natural gas or petroleum.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... mixture of solar energy (including wind, tide, and other intermittent sources) and petroleum or natural gas, where: (1) Solar energy will account for at least 20 percent of the total annual Btu heat input... 10 Energy 4 2012-01-01 2012-01-01 false Permanent exemption for certain fuel mixtures...

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

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... mixture of solar energy (including wind, tide, and other intermittent sources) and petroleum or natural gas, where: (1) Solar energy will account for at least 20 percent of the total annual Btu heat input... 10 Energy 4 2013-01-01 2013-01-01 false Permanent exemption for certain fuel mixtures...

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

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... mixture of solar energy (including wind, tide, and other intermittent sources) and petroleum or natural gas, where: (1) Solar energy will account for at least 20 percent of the total annual Btu heat input... 10 Energy 4 2011-01-01 2011-01-01 false Permanent exemption for certain fuel mixtures...

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

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... mixture of solar energy (including wind, tide, and other intermittent sources) and petroleum or natural gas, where: (1) Solar energy will account for at least 20 percent of the total annual Btu heat input... 10 Energy 4 2014-01-01 2014-01-01 false Permanent exemption for certain fuel mixtures...

  1. Dielectric Properties of Cryogenic Gas Mixtures Containing Helium, Neon, and Hydrogen

    NASA Astrophysics Data System (ADS)

    Graber, L.; Kim, W. J.; Cheetham, P.; Kim, C. H.; Rodrigo, H.; Pamidi, S. V.

    2015-12-01

    Past efforts of cooling high temperature superconducting (HTS) power cables by gaseous cryogens focused exclusively on helium. The limited dielectric strength of helium gas necessitated alternatives that could be used in the temperature range suitable for HTS power applications. This paper presents the benefits of gas mixtures containing helium with small concentrations of hydrogen or neon to mitigate the limited dielectric strength of pure helium gas. The expectation was that such gas mixtures could improve dielectric characteristics while maintaining the thermal, non-flammable and non-corrosive properties of pure helium gas. The AC breakdown voltage of helium gas mixtures containing 4 mol% neon or 4 mol% hydrogen respectively have been measured and compared to those of pure helium and pure neon. All measurements were performed at 77 K at gas pressure levels between 0.5 and 2.0 MPa. While the 4 mol% neon mixture did not result in any improvement over pure helium, the 4 mol% hydrogen mixture resulted in 80% higher breakdown strength. This is expected to enable higher operating voltages for gas cooled HTS power devices.

  2. Grad's moment method for relativistic gas mixtures of Maxwellian particles

    NASA Astrophysics Data System (ADS)

    Kremer, Gilberto M.; Marques, Wilson

    2013-01-01

    Mixtures of relativistic gases are analyzed within the framework of Boltzmann equation by using Grad's moment method. A relativistic mixture of r constituent is characterized by the moments of the distribution function: particle four-flows, energy-momentum tensors, and third-order moment tensors. By using Eckart's decomposition and introducing 13r + 1 scalar fields - related with the four-velocity, temperature of the mixture, particle number densities, diffusion fluxes, non-equilibrium pressures, heat fluxes, and pressure deviator tensors - Grad's distribution functions are obtained. Grad's distribution functions are used to determine the third-order tensors and their production terms for mixtures whose constituent's rest masses are not too disparate, so that it follows a system of 13r + 1 scalar field equations. By restricting to a binary mixture characterized by the six fields of partial particle number densities, four-velocity and temperature, the remainder 21 scalar equations are used to determine the constitutive equations for the non-equilibrium pressures, diffusion fluxes, pressure deviator tensors, and heat fluxes. Hence the Navier-Stokes and generalized Fourier and Fick laws are obtained and the transport coefficients of bulk and shear viscosities, thermal conductivity, diffusion, thermal-diffusion, and diffusion-thermal are determined. Analytic expressions for the transport coefficients in the non-relativistic and ultra-relativistic limiting cases are given. Furthermore, solutions of the relativistic field equations for the binary mixture are obtained in form of forced and free waves. In the low frequency limiting case the phase velocity and the attenuation coefficient are determined for forced waves. In the small wavenumber limiting case it is shown that there exist four longitudinal eigenmodes, two of them corresponding to propagating sound modes and two associated with non-propagating diffusive modes.

  3. Gas gain limitation in low pressure proportional counters filled with TEG mixtures

    NASA Astrophysics Data System (ADS)

    Kowalski, T. Z.

    2014-12-01

    Proportional counters filled with tissue equivalent gas mixtures (TEPC) can be used to simulate interactions and energy transferred to small tissue volumes. One criteria which allows to use TEPC as the dose meter is that the particle ranges are larger compared to the gas volume. TEPC achieve this by operating at low gas pressures. Single ionization events dominate the distribution of low-LET radiation at low gas pressure and therefore their detection is of primary importance, a high gas gain is necessary. Therefore gas gain factor has been measured for Methane- and Propane-based tissue equivalent gas mixtures. The highest stable gas gains, second ionization Townsend coefficient and electron avalanche dimensions have been determined.

  4. 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

    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)

  5. Current assessment of the potential of dielectric gas mixtures for industrial applications

    NASA Astrophysics Data System (ADS)

    Bouldin, D. W.; James, D. R.; Pace, M. O.; Christophorou, L. G.

    1984-04-01

    The need for more efficient, economical electrical power transmission and distribution has given impetus to the investigation of new insulating gases. Since no single gas meets all of the multiple needs and operating conditions that exist in power apparatus, mixtures were studied with the goal of tailoring the dielectric for a specific application by exploiting the properties of the component gases. Research results on dielectric gas mixtures and assesses the potential of such mixtures for industrial applications are reviewed. The topics considered include electrical breakdown characteristics, physical and chemical properties, and economics.

  6. Electron temperature and density measurement of tungsten inert gas arcs with Ar-He shielding gas mixture

    NASA Astrophysics Data System (ADS)

    Kühn-Kauffeldt, M.; Marques, J.-L.; Forster, G.; Schein, J.

    2013-10-01

    The diagnostics of atmospheric welding plasma is a well-established technology. In most cases the measurements are limited to processes using pure shielding gas. However in many applications shielding gas is a mixture of various components including metal vapor in gas metal arc welding (GMAW). Shielding gas mixtures are intentionally used for tungsten inert gas (TIG) welding in order to improve the welding performance. For example adding Helium to Argon shielding gas allows the weld geometry and porosity to be influenced. Yet thermal plasmas produced with gas mixtures or metal vapor still require further experimental investigation. In this work coherent Thomson scattering is used to measure electron temperature and density in these plasmas, since this technique allows independent measurements of electron and ion temperature. Here thermal plasmas generated by a TIG process with 50% Argon and 50% Helium shielding gas mixture have been investigated. Electron temperature and density measured by coherent Thomson scattering have been compared to the results of spectroscopic measurements of the plasma density using Stark broadening of the 696.5 nm Argon spectral line. Further investigations of MIG processes using Thomson scattering technique are planned.

  7. Emission spectroscopic study on gas-gas interactions in glow discharge plasmas using several binary gas mixtures.

    PubMed

    Wagatsuma, Kazuaki

    2010-01-01

    Emission spectra of constituent gas species from glow discharge plasmas using argon-helium, krypton-helium, argon-krypton, and krypton-argon gas mixtures were analyzed to elucidate collisional energy transfer between these gas species occurring in the plasma. In the argon-helium mixed gas plasma, the enhancement or quenching of particular Ar II lines was observed when helium was added to an argon-matrix glow discharge plasma, meaning that a redistribution in the population among the excited levels could be induced through argon-helium collisions. On the other hand, the krypton-helium plasma showed little change in the emission intensities of Kr II lines when helium was added to a krypton-matrix glow discharge plasma, meaning that energy exchanges between krypton and helium excited species occur inactively. These phenomena are principally because the excitation energy as well as the spin multiplicity between collision partners follow both the energy resonance conditions and the spin conservation rule in collisions of the second kind in the argon-helium system, but not in the krypton-helium system. In the argon-krypton and krypton-argon mixed gas plasmas, significant intensity changes of particular Ar II or Kr II lines could not be found; therefore, there were no dominant channels for energy exchanges between argon and krypton species in the mixed gas plasmas. PMID:20215678

  8. Hyperpolarized xenon magnetic resonance of the lung and the brain

    NASA Astrophysics Data System (ADS)

    Venkatesh, Arvind Krishnamachari

    2001-04-01

    Hyperpolarized noble gas Magnetic Resonance Imaging (MRI) is a new diagnostic modality that has been used successfully for lung imaging. Xenon is soluble in blood and inhaled xenon is transported to the brain via circulating blood. Xenon also accumulates in the lipid rich white matter of the brain. Hyperpolarized xenon can hence be used as a tissue- sensitive probe of brain function. The goals of this study were to identify the NMR resonances of xenon in the rat brain and evaluate the role of hyperpolarized xenon for brain MRI. We have developed systems to produce sufficient volumes of hyperpolarized xenon for in vivo brain experiments. The specialized instrumentation developed include an apparatus for optical pump-cell manufacture and high purity gas manifolds for filling cells. A hyperpolarized gas delivery system was designed to ventilate small animals with hyperpolarized xenon for transport to the brain. The T1 of xenon dissolved in blood indicates that the lifetime of xenon in the blood is sufficient for significant magnetization to be transferred to distal tissues. A variety of carrier agents for intravenous delivery of hyperpolarized xenon were tested for transport to distal tissues. Using our new gas delivery system, high SNR 129Xe images of rat lungs were obtained. Spectroscopy with hyperpolarized xenon indicated that xenon was transported from the lungs to the blood and tissues with intact magnetization. After preliminary studies that indicated the feasibility for in vivo rat brain studies, experiments were performed with adult rats and young rats with different stages of white matter development. Both in vivo and in vitro experiments showed the prominence of one peak from xenon in the rat brain, which was assigned to brain lipids. Cerebral brain perfusion was calculated from the wash-out of the hyperpolarized xenon signal in the brain. An increase in brain perfusion during maturation was observed. These experiments showed that hyperpolarized xenon MRI can be used to develop unique approaches to studying white matter and gray matter in the brain. Some of the possible applications of hyperpolarized xenon MRI in the brain are clinical diagnosis of white matter diseases, functional MRI (fMRI) and measurement of cerebral blood perfusion.

  9. Xenon Blocks Neuronal Injury Associated with Decompression.

    PubMed

    Blatteau, Jean-Eric; David, Hélène N; Vallée, Nicolas; Meckler, Cedric; Demaistre, Sebastien; Lambrechts, Kate; Risso, Jean-Jacques; Abraini, Jacques H

    2015-01-01

    Despite state-of-the-art hyperbaric oxygen (HBO) treatment, about 30% of patients suffering neurologic decompression sickness (DCS) exhibit incomplete recovery. Since the mechanisms of neurologic DCS involve ischemic processes which result in excitotoxicity, it is likely that HBO in combination with an anti-excitotoxic treatment would improve the outcome in patients being treated for DCS. Therefore, in the present study, we investigated the effect of the noble gas xenon in an ex vivo model of neurologic DCS. Xenon has been shown to provide neuroprotection in multiple models of acute ischemic insults. Fast decompression compared to slow decompression induced an increase in lactate dehydrogenase (LDH), a well-known marker of sub-lethal cell injury. Post-decompression administration of xenon blocked the increase in LDH release induced by fast decompression. These data suggest that xenon could be an efficient additional treatment to HBO for the treatment of neurologic DCS. PMID:26469983

  10. Xenon Blocks Neuronal Injury Associated with Decompression

    PubMed Central

    Blatteau, Jean-Eric; David, Hélène N.; Vallée, Nicolas; Meckler, Cedric; Demaistre, Sebastien; Lambrechts, Kate; Risso, Jean-Jacques; Abraini, Jacques H.

    2015-01-01

    Despite state-of-the-art hyperbaric oxygen (HBO) treatment, about 30% of patients suffering neurologic decompression sickness (DCS) exhibit incomplete recovery. Since the mechanisms of neurologic DCS involve ischemic processes which result in excitotoxicity, it is likely that HBO in combination with an anti-excitotoxic treatment would improve the outcome in patients being treated for DCS. Therefore, in the present study, we investigated the effect of the noble gas xenon in an ex vivo model of neurologic DCS. Xenon has been shown to provide neuroprotection in multiple models of acute ischemic insults. Fast decompression compared to slow decompression induced an increase in lactate dehydrogenase (LDH), a well-known marker of sub-lethal cell injury. Post-decompression administration of xenon blocked the increase in LDH release induced by fast decompression. These data suggest that xenon could be an efficient additional treatment to HBO for the treatment of neurologic DCS. PMID:26469983

  11. Chemically-bound xenon in fibrous silica.

    PubMed

    Kalinowski, Jaroslaw; Rsnen, Markku; Gerber, R Benny

    2014-06-21

    High-level quantum chemical calculations reported here predict the existence and remarkable stability, of chemically-bound xenon atoms in fibrous silica. The results may support the suggestion of Sanloup and coworkers that chemically-bound xenon and silica account for the problem of "missing xenon" (by a factor of 20!) from the atmospheres of Earth and Mars. So far, the host silica was assumed to be quartz, which is in contradiction with theory. The xenon-fibrous silica molecule is computed to be stable well beyond room temperature. The calculated Raman spectra of the species agree well with the main features of the experiments by Sanloup et al. The results predict computationally the existence of a new family of noble-gas containing materials. The fibrous silica species are finite molecules, their laboratory preparation should be feasible, and potential applications are possible. PMID:24807740

  12. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... gas and other material. 173.305 Section 173.305 Transportation Other Regulations Relating to... Packaging § 173.305 Charging of cylinders with a mixture of compressed gas and other material. (a) Detailed requirements. A mixture of a compressed gas and any other material must be shipped as a compressed gas if...

  13. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... gas and other material. 173.305 Section 173.305 Transportation Other Regulations Relating to... Packaging § 173.305 Charging of cylinders with a mixture of compressed gas and other material. (a) Detailed requirements. A mixture of a compressed gas and any other material must be shipped as a compressed gas if...

  14. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... gas and other material. 173.305 Section 173.305 Transportation Other Regulations Relating to... Packaging § 173.305 Charging of cylinders with a mixture of compressed gas and other material. (a) Detailed requirements. A mixture of a compressed gas and any other material must be shipped as a compressed gas if...

  15. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... gas and other material. 173.305 Section 173.305 Transportation Other Regulations Relating to... Packaging § 173.305 Charging of cylinders with a mixture of compressed gas and other material. (a) Detailed requirements. A mixture of a compressed gas and any other material must be shipped as a compressed gas if...

  16. 49 CFR 173.305 - Charging of cylinders with a mixture of compressed gas and other material.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... gas and other material. 173.305 Section 173.305 Transportation Other Regulations Relating to... Packaging § 173.305 Charging of cylinders with a mixture of compressed gas and other material. (a) Detailed requirements. A mixture of a compressed gas and any other material must be shipped as a compressed gas if...

  17. Direct nuclear excitation of a He-3 - CO2 gas mixture

    NASA Technical Reports Server (NTRS)

    Jalufka, N. W.

    1981-01-01

    Probe measurements using a continuous wave CO2 laser have been carried out on a He-3 - CO2 gas mixture directly excited by the He-3(n,p)H-3 reaction. At a gas pressure of 1 atm and thermal neutron flux up to 10 to the 17th n/sq cm sec, total extinction of the probe beam was observed. Addition of N2 to the gas mixture (up to 20%) produced a media such as is used in electric discharge CO2 lasers. However, this mixture produced the same results as the He-3 - CO2 mixture. Absorption of the laser beam indicates that with direct nuclear excitation, it is the lower laser level which is excited. Therefore direct nuclear pumping of a CO2 laser does not appear feasible.

  18. 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.

  19. Recovering Residual Xenon Propellant for an Ion Propulsion System

    NASA Technical Reports Server (NTRS)

    Ganapathi, Gani; Skakkottai, P.; wu, Jiunn Jeng

    2006-01-01

    Future nuclear-powered Ion-Propulsion- System-propelled spacecraft such as Jupiter Icy Moon Orbiter (JIMO) will carry more than 10,000 kg of xenon propellant. Typically, a small percentage of this propellant cannot be used towards the end of the mission because of the pressure drop requirements for maintaining flow. For large missions such as JIMO, this could easily translate to over 250 kg of unusable xenon. A proposed system, the Xenon Recovery System (XRS), for recovering almost all of the xenon remaining in the tank, would include a cryopump in the form of a condenser/evaporator that would be alternatively cooled by a radiator, then heated electrically. When the pressure of the xenon in the tank falls below 0.7 MPa (100 psia), the previously isolated XRS will be brought online and the gas from the tank would enter the cryopump that is initially cooled to a temperature below saturation temperature of xenon. This causes xenon liquefaction and further cryopumping from the tank till the cryopump is full of liquid xenon. At this point, the cryopump is heated electrically by small heaters (70 to 80 W) to evaporate the liquid that is collected as high-pressure gas (<7 MPa; 1,000 psia) in an intermediate accumulator. Check valves between the tank and the XRS prevent the reverse flow of xenon during the heating cycle. The accumulator serves as the high-pressure source of xenon gas to the Xenon Feed System (XFS) downstream of the XRS. This cycle is repeated till almost all the xenon is recovered. Currently, this system is being baselined for JIMO.

  20. A concentration measurement system for binary gas mixtures using two flowmeters

    NASA Astrophysics Data System (ADS)

    Yamazaki, Shunpei; Funaki, Tatsuya; Kawashima, Kenji; Kagawa, Toshiharu

    2007-09-01

    A system has been constructed for measurement of the gas concentration in a binary gas mixture and of the total flow rate of the gas mixture, using a venturi flowmeter and a laminar flowmeter. The flow rate and air concentration in tested gas mixtures, consisting of air and carbon dioxide or helium, are measured. The results are compared with reference values and the obtained results are found to be similar to those obtained using existing flowmeters and concentration meters. The response of the system to the flow rate and the mixing ratio change is tested. The flow rate change response is approximately equivalent to existing flowmeters, and the concentration change response is better than for existing meters.

  1. Accuracy Improvement of a Concentration and Flow Measurement System for Binary Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Youn, Chongho; Kogo, Akira; Kawashima, Kenji; Kagawa, Toshiharu

    This study intends to improve the accuracy of the concentration and flow measurement system for binary gas mixtures that was developed by two of the present authors1). This system is composed of a venturi tube and a laminar flowmeter connected in series. A basic examination on the viscosity estimate for binary gas mixtures and a preliminary measurement of the flow coefficient of the venturi tube are carried out. The procedure of concentration calculation based on the basic study is also shown. The estimate accuracy of the mole fractions of component gases and the flow rate of binary gas mixtures are experimentally examined using three kinds of mixed gas: CO2-Air, CO2-Ar and Ar-He. The results indicate that the mole fractions can be estimated with accuracy of 5% and the flow rate can be estimated with accuracy of 2%.

  2. Effects of various gas mixtures on plasma nitriding behavior of AISI 5140 steel

    SciTech Connect

    Karakan, Mehmet; Alsaran, Akguen; Celik, Ayhan

    2002-10-15

    AISI 5140 steel was plasma nitrided at various gas mixtures of nitrogen, hydrogen, and argon to investigate the actions of hydrogen and argon on plasma nitriding. The structural and mechanical properties of ion-nitrided AISI 5140 steel have been assessed by evaluating composition of phases, surface hardness, compound layer thickness, and case depth by using X-ray diffraction (XRD), microhardness tests, and scanning electron microscopy (SEM). It was found that the growth of compound layer can be controlled and the diffusion improved when the gas mixture includes H{sub 2} gas. Additionally, it was determined that the amount of Ar in dual gas mixture must be at 20% minimum to obtain distinctive surface hardness and compound layer thickness.

  3. Xenon Isotopes in Irradiated and Unirradiated Samples of ALH84001

    NASA Astrophysics Data System (ADS)

    Gilmour, J. D.; Whitby, J. A.; Ash, R. D.; Turner, G.

    1995-09-01

    Interior samples .110, .111, .112, altered sample .127 and fusion crust sample .136 from the SNC meteorite ALH 84001 [1] have been studied. Approximately 3mg of each sample was degassed stepwise in five minute heating steps on a filament. Temperature was monitored with an optical pyrometer while the chamber pressure was measured with a capacitance manometer. An aliquot (~1% ) of the evolved gas was characterised using a quadrupole mass spectrometer, the remainder was gettered and admitted to the RELAX mass spectrometer [2] for xenon isotopic analysis. The data obtained from 5 unirradiated samples is shown in figure 1. These data are consistent with a mixing among terrestrial (air) xenon, SPB-xenon [3] and Chassigny-like xenon [4], with a maximum 129Xe/132Xe of 1.92 and a minimum 136Xe/132Xe of 0.313. There is no evidence of the excess (i.e. exceeding that required to be on the SPB-Chassigny mixing line) 129Xe previously attributed to a heterogeneously distributed 129Xe-rich component [5]. This absence could be explained by the mixture of air xenon into even the most 129Xe rich of our extractions or by our smaller samples (3-4mg vs 142mg) having failed to sample this phase. Samples of .127, .111 and .112 were irradiated with a thermal neutron fluence of 7.22x10^18 n cm^-2. Each showed a marked peak release of excesses of 129Xe and reactor-derived isotopes (128Xe, 131Xe, 136Xe) at high temperature (1500-1800 degrees C), while the 129Xe/128Xe showed an increase with temperature and was consistent in the largest releases from each sample. (Excesses are calculated assuming 130Xe was derived from a Chassigny component.) Excess 128Xe always accompanied excess 129Xe and the high temperature points (containing 50% of the excess 129Xe evolved) from the 3 samples define a mixing line with Chassigny. However, more data is needed to establish a true correlation. The fission isotope ratios in the irradiated samples are consistent with neutron-induced fission of 235U, and indicate an abundance of around 20ppb (total U). Assuming xenon has a 4 billion year closure age as argon does [6], the 238U spontaneous fission contribution to a typical high-temperature, SPB xenon-rich extraction is ~1%. The major release of active gases in each sample (unirradiated and irradiated) was between 600 and 800 deg C and was composed of CO2 and CO. Evolved gas pressures were converted to equivalent masses of carbonate assuming published Mg - Ca - Fe abundances for this phase [1]; altered sample .127 contained 5 times as much carbonate as the mean of the other samples (0.4% vs 0.08%). The inferred xenon content of the carbonate was significantly above blank in only one unirradiated sample and yielded a carbonate 130Xe content of 6x10^-10 cc STP/g and 129Xe/132Xe=1.03+/-0.03, 136Xe/132Xe=0.33+/-0.02, indicating that carbonate is not the major carrier of SPB-Xe in these samples. Significant excesses of 128Xe and 131Xe were associated with the CO/CO2 release in the irradiated sample of .127. References: [1] Mittlefehldt D. W. (1994) Meteoritics, 29, 214-221. [2] Gilmour J. D. et al. (1994) Rev. Sci. Instrum., 65, 617-625. [3] Swindle T. D. et al. (1986) GCA, 52, 1001-1015. [4] Ott U. (1988) GCA, 52, 1937-1948. [5] Swindle T. D. et al. (1995) GCA, 59, 793-801. [6] Ash R. D. et al., this volume.

  4. Proton irradiation of simple gas mixtures: Influence of irradiation parameters

    NASA Technical Reports Server (NTRS)

    Sack, Norbert J.; Schuster, R.; Hofmann, A.

    1990-01-01

    In order to get information about the influence of irradiation parameters on radiolysis processes of astrophysical interest, methane gas targets were irradiated with 6.5 MeV protons at a pressure of 1 bar and room temperature. Yields of higher hydrocarbons like ethane or propane were found by analysis of irradiated gas samples using gas chromatography. The handling of the proton beam was of great experimental importance for determining the irradiation parameters. In a series of experiments current density of the proton beam and total absorbed energy were shown to have a large influence on the yields of produced hydrocarbons. Mechanistic interpretations of the results are given and conclusions are drawn with regard to the chemistry and the simulation of various astrophysical systems.

  5. Some possibilities of using gas mixtures other than air in aerodynamic research

    NASA Technical Reports Server (NTRS)

    Chapman, Dean R

    1956-01-01

    A study is made of the advantages that can be realized in compressible-flow research by employing a substitute heavy gas in place of air. The present report is based on the idea that by properly mixing a heavy monatomic gas with a suitable heavy polyatomic gas, it is possible to obtain a heavy gas mixture which has the correct ratio of specific heats and which is nontoxic, nonflammable, thermally stable, chemically inert, and comprised of commercially available components. Calculations were made of wind-tunnel characteristics for 63 gas pairs comprising 21 different polyatomic gases properly mixed with each of three monatomic gases (argon, krypton, and zenon).

  6. Xenon Tetrafluoride: Crystal Structure.

    PubMed

    Ibers, J A; Hamilton, W C

    1963-01-11

    On the basis of a three-dimensional x-ray analysis, the xenon tetrafluoride molecule in the solid is planar; the approximate symmetry is D(4h). The average distance between the xenon and the fluorine is 1.92 +/- 0.03 A. PMID:17798707

  7. 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.

    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.

  8. 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.

  9. Inflammable Gas Mixture Detection with a Single Catalytic Sensor Based on the Electric Field Effect

    PubMed Central

    Tong, Ziyuan; Tong, Min-Ming; Meng, Wen; Li, Meng

    2014-01-01

    This paper introduces a new way to analyze mixtures of inflammable gases with a single catalytic sensor. The analysis technology was based on a new finding that an electric field on the catalytic sensor can change the output sensitivity of the sensor. The analysis of mixed inflammable gases results from processing the output signals obtained by adjusting the electric field parameter of the catalytic sensor. For the signal process, we designed a group of equations based on the heat balance of catalytic sensor expressing the relationship between the output signals and the concentration of gases. With these equations and the outputs of different electric fields, the gas concentration in a mixture could be calculated. In experiments, a mixture of methane, butane and ethane was analyzed by this new method, and the results showed that the concentration of each gas in the mixture could be detected with a single catalytic sensor, and the maximum relative error was less than 5%. PMID:24717635

  10. Terrestrial fission xenon: choice of primordial isotopic composition

    SciTech Connect

    Levskii, L.

    1983-06-30

    A new composition of primordial terrestrial xenon is derived, on the assumption that it lies on an extension of the mixing line between solar Xe and anomalous (CCF) Xe in carbonaceous chondrites. With this composition, the apparent fission components in atmospheric and well gas Xe become larger, and resemble Pu-244 fission xenon. 7 references.

  11. Numerical simulation of the passive gas mixture flow

    NASA Astrophysics Data System (ADS)

    Kyncl, Martin; Pelant, Jaroslav

    2016-03-01

    The aim of this paper is the numerical solution of the equations describing the non-stationary compressible turbulent multicomponent flow in gravitational field. The mixture of perfect inert gases is assumed. We work with the RANS equations equipped with the k-omega and the EARSM turbulence models. For the simulation of the wall roughness we use the modification of the specific turbulent dissipation. The finite volume method is used, with thermodynamic constants being functions in time and space. In order to compute the fluxes through the boundary faces we use the modification of the Riemann solver, which is the original result. We present the computational results, computed with the own-developed code (C, FORTRAN, multiprocessor, unstructured meshes in general).

  12. 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

    ... feasible for the unit to use a mixture of petroleum or natural gas and coal or another alternate fuel as a... petroleum or natural gas and coal or another alternate fuel as a primary energy source, for purposes of this... gas in mixtures-certifying powerplants. 504.8 Section 504.8 Energy DEPARTMENT OF ENERGY...

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

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... feasible for the unit to use a mixture of petroleum or natural gas and coal or another alternate fuel as a... petroleum or natural gas and coal or another alternate fuel as a primary energy source, for purposes of this... gas in mixtures-certifying powerplants. 504.8 Section 504.8 Energy DEPARTMENT OF ENERGY...

  14. 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

    ... feasible for the unit to use a mixture of petroleum or natural gas and coal or another alternate fuel as a... petroleum or natural gas and coal or another alternate fuel as a primary energy source, for purposes of this... gas in mixtures-certifying powerplants. 504.8 Section 504.8 Energy DEPARTMENT OF ENERGY...

  15. 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

    ... feasible for the unit to use a mixture of petroleum or natural gas and coal or another alternate fuel as a... petroleum or natural gas and coal or another alternate fuel as a primary energy source, for purposes of this... gas in mixtures-certifying powerplants. 504.8 Section 504.8 Energy DEPARTMENT OF ENERGY...

  16. 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

    ... feasible for the unit to use a mixture of petroleum or natural gas and coal or another alternate fuel as a... petroleum or natural gas and coal or another alternate fuel as a primary energy source, for purposes of this... gas in mixtures-certifying powerplants. 504.8 Section 504.8 Energy DEPARTMENT OF ENERGY...

  17. 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.

  18. Acoustic attenuation in gas mixtures with nitrogen: experimental data and calculations.

    PubMed

    Ejakov, Sally G; Phillips, Scott; Dain, Yefim; Lueptow, Richard M; Visser, Jacobus H

    2003-04-01

    Attenuation in a gas results from a combination of classical attenuation, attenuation from diffusion, and attenuation due to molecular relaxation. In previous papers [J. Acoust. Soc. Am. 109, 1955 (2001); 110, 2974 (2001)] a model is described that predicts the attenuation from vibrational relaxation in gas mixtures. In order to validate this model, the attenuation was measured using a pulse technique with four transducer pairs, each with a different resonant frequency. The attenuation calculated using the model was compared to the measured values for a variety of gases including: air, oxygen, methane, hydrogen, and mixtures of oxygen/nitrogen, methane/nitrogen, carbon dioxide/nitrogen, and hydrogen/nitrogen. After the measured data is corrected for diffraction, the model matches the trends in the measured attenuation spectrum for this extensive set of gas mixtures. PMID:12703699

  19. CO2 + N2O mixture gas hydrate formation kinetics and effect of soil minerals on mixture-gas hydrate formation process

    NASA Astrophysics Data System (ADS)

    Enkh-Amgalan, T.; Kyung, D.; Lee, W.

    2012-12-01

    CO2 mitigation is one of the most pressing global scientific topics in last 30 years. Nitrous oxide (N2O) is one of the main greenhouse gases (GHGs) defined by the Kyoto Protocol and its global warming potential (GWP) of one metric ton is equivalent to 310 metric tons of CO2. They have similar physical and chemical properties and therefore, mixture-gas (50% CO2 + 50% N2O) hydrate formation process was studied experimentally and computationally. There were no significant research to reduce N20 gas and we tried to make hydrate to mitigate N20 and CO2 in same time. Mixture gas hydrate formation periods were approximately two times faster than pure N2O hydrate formation kinetic in general. The fastest induction time of mixture-gas hydrate formation observed in Illite and Quartz among various soil mineral suspensions. It was also observed that hydrate formation kinetic was faster with clay mineral suspensions such as Nontronite, Sphalerite and Montmorillonite. Temperature and pressure change were not significant on hydrate formation kinetic; however, induction time can be significantly affected by various chemical species forming under the different suspension pHs. The distribution of chemical species in each mineral suspension was estimated by a chemical equilibrium model, PHREEQC, and used for the identification of hydrate formation characteristics in the suspensions. With the experimental limitations, a study on the molecular scale modeling has a great importance for the prediction of phase behavior of the gas hydrates. We have also performed molecular dynamics computer simulations on N2O and CO2 hydrate structures to estimate the residual free energy of two-phase (hydrate cage and guest molecule) at three different temperature ranges of 260K, 273K, and 280K. The calculation result implies that N2O hydrates are thermodynamically stable at real-world gas hydrate existing condition within given temperature and pressure. This phenomenon proves that mixture-gas could be efficiently applied to CO2 sequestration at potential sites and further investigations must be conducted to identify possible effects frequently found in natural geological environments and geo-environmental conditions at the site affecting the hydrate formation kinetics.

  20. Liquid-vapor interface of water-methanol mixture. II. A simple lattice-gas model

    NASA Astrophysics Data System (ADS)

    Matsumoto, Mitsuhiro; Mizukuchi, Hiroshi; Kataoka, Yosuke

    1993-01-01

    A simple lattice-gas model with a mean field approximation is presented to investigate qualitative features of liquid-vapor interface of water-methanol mixtures. The hydrophobicity of methanol molecules is incorporated by introducing anisotropic interactions. A rigorous framework to treat such anisotropy in a lattice-gas mixture model is described. The model is mathematically equivalent to an interfacial system of a diluted antiferro Ising spin system. Results of density profiles, orientational ordering near the surface, and surface excess thermodynamic quantities are compared with results of computer simulation based on a more realistic model.

  1. 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.

  2. Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids

    SciTech Connect

    Finotello Alexia; Bara Jason E.; Narayan Suguna; Campder Dean; Noble Richard D.

    2008-07-01

    This study focuses on the solubility behaviors of CO{sub 2}, CH{sub 4}, and N{sub 2} gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using l-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide ((C{sub 2}mim)(Tf{sub 2}N)) and l-ethyl-3-methylimidazolium tetrafluoroborate ((C{sub 2}mim)(BF{sub 4})) at 40{sup o}C and low pressures (about 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % (C{sub 2}mim)(BF{sub 4}) in (C{sub 2}-mim)(Tf2{sub N}). Results show that regular solution theory (RST) can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Interestingly, the solubility selectivity, defined as the ratio of gas mole fractions in the RTIL mixture, of CO{sub 2} with N{sub 2} or CH{sub 4} in pure (C{sub 2}mim)(BF4) can be enhanced by adding 5 mol% (C{sub 2}-mim)(Tf{sub 2}N).

  3. Recognizing indoor formaldehyde in binary gas mixtures with a micro gas sensor array and a neural network

    NASA Astrophysics Data System (ADS)

    Lv, Pin; Tang, Zhenan; Wei, Guangfen; Yu, Jun; Huang, Zhengxing

    2007-09-01

    Low-concentration formaldehyde (HCHO) together with ethanol/toluene/acetone/α-pinene (as an interference gas of HCHO) is detected with a micro gas sensor array, composed of eight tin oxide (SnO2) thin film gas sensors with Au, Cu, Pt or Pd metal catalysts. The characteristics of the multi-dimensional signals from the eight sensors are evaluated. A multilayer neural network with an error backpropagation (BP) learning algorithm, plus the principal component analysis (PCA) technique, is implemented to recognize these indoor volatile organic compounds (VOC). The results show that the micro gas sensor array, plus the multilayer neural network, is very effective in recognizing 0.06 ppm HCHO in single gas component and in binary gas mixtures, toluene/ethanol/α-pinene with small relative error.

  4. 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.

  5. Microdosimetric response of proportional counters filled with different tissue equivalent gas mixtures

    NASA Astrophysics Data System (ADS)

    Kowalski, T. Z.

    2015-03-01

    In pulse mode operation each detector at the output gives pulse height spectra. These pulse height spectra from proportional counters filled with tissue-equivalent gas are recalculated to microdosimetric quantity for expressing the radiation quality. Energy spectra of 90Sr, 109Cd and 137Cs sources have been measured for different in geometry proportional counters for Methane- and Propane-based tissue equivalent gas (TEG) mixtures. The mixtures pressures were varied in the range from 20 hPa to 200 hPa to have simulated tissue target diameter of the order of a few μm, from 0,3 μm to 7 μm. Differences, up to 20% in the average deposited energy due to different TEG mixtures were observed.

  6. 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.

    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.

  7. Program on the combustion chemistry of low- and intermediate-Btu gas mixtures

    SciTech Connect

    Not Available

    1981-11-30

    Low and intermediate Btu (LBTU and IBTU) gas mixtures are essentially mixtures of CO, H/sub 2/ and CH/sub 4/ diluted with nitrogen and CO/sub 2/. Although the combustion properties of these three fuels have been extensively investigated and their individual combustion kinetics are reasonably well established, prediction techniques for applying these gas mixtures remain for the most part empirical. This program has aimed to bring together and apply some of the fundamental combustion parameters to the CO-H/sub 2/-CH/sub 4/ flame system with the hope of reducing some of this empiricism. Four topical reports have resulted from this program. This final report summarizes these reports and other activities undertaken in this program. This program was initiated June 22, 1976 under ERDA Contract No. E(49-18)-2406 and was later continued under DOE/PETC and DOE Contract No. DE-AC22-76ET10653.

  8. Experimental study of flammability limits of natural gas-air mixture.

    PubMed

    Liao, S Y; Cheng, Q; Jiang, D M; Gao, J

    2005-03-17

    Flammability limits data are essential for a quantitative risk assessment of explosion hazard associated with the use of combustible gas. The present work is to obtain the fundamental flammability data for prevention of the hazards in the practical applications. Experiments have been conducted in a constant volume combustion bomb, and the fuel considered here is natural gas (NG). The pressure histories in the combustion bomb are recorded and a criterion of 7% pressure rise has been used to judge a flammable mixture. The effects of ethane on NG-air flammability limits have been investigated. By adding diluent (carbon dioxide, nitrogen or their mixture) into NG-air mixture, the dilution effects on the flammability limits have been explored as well, and the results are plotted as functions of diluent ratio. PMID:15752851

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

    NASA Astrophysics Data System (ADS)

    Kazantsev, S. Yu.; Kononov, I. G.; Kossyi, I. A.; Tarasova, N. M.; Firsov, K. N.

    2009-03-01

    Ignition of a stoichiometric CH4: O2 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 μs, 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.

  10. Binary and ternary gas mixtures for use in glow discharge closing switches

    SciTech Connect

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

    1990-01-23

    This patent describes a capacitive energy storage system. It comprises: a diffuse-discharge switch; a gas mixture in the diffuse-discharge switch comprising a mixture of He, Ne and Ar in combination with a second compound selected from the group consisting of (CF{sub 3}){sub 2}O, CF{sub 4}, BF{sub 3}, GeF{sub 4}, WF{sub 6}, SiF{sub 4}, in combination with a compound selected from the group consisting of TMPD, TMBI, TMAE, TMAB, triethylamine, methylaniline, diethylamine, aniline, Co-ocene, Ch-ocene, Ni-ocene and Fe-ocene; and means for selectively activating the gas mixture to an electrical conductive state.

  11. Hydrocracking of vacuum gas oil-vegetable oil mixtures for biofuels production.

    PubMed

    Bezergianni, Stella; Kalogianni, Aggeliki; Vasalos, Iacovos A

    2009-06-01

    Hydrocracking of vacuum gas oil (VGO)--vegetable oil mixtures is a prominent process for the production of biofuels. In this work both pre-hydrotreated and non-hydrotreated VGO are assessed whether they are suitable fossil components in a VGO-vegetable oil mixture as feed-stocks to a hydrocracking process. This assessment indicates the necessity of a VGO pre-hydrotreated step prior to hydrocracking the VGO-vegetable oil mixture. Moreover, the comparison of two different mixing ratios suggests that higher vegetable oil content favors hydrocracking product yields and qualities. Three commercial catalysts of different activity are utilized in order to identify a range of products that can be produced via a hydrocracking route. Finally, the effect of temperature on hydrocracking VGO-vegetable oil mixtures is studied in terms of conversion and selectivity to diesel, jet/kerosene and naphtha. PMID:19231171

  12. 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)...

  13. Concentration measurement systems with stable solutions for binary gas mixtures using two flowmeters

    NASA Astrophysics Data System (ADS)

    Youn, Chongho; Kawashima, Kenji; Kagawa, Toshiharu

    2011-06-01

    The previously proposed gas concentration measurement system (Yamazaki et al 2007 Meas. Sci. Technol. 18 2762-8) shows a considerable error for some combinations of gases. The error increases when the system of equations determining mole fractions becomes a mathematically ill-conditioned system. Because the parameters of the equations reflect the material properties of the gases, the current paper considers flowmeters whose flow rate indication does not involve any gas property. This paper firstly illustrates the ill condition for the combination of venturi meter and laminar flowmeters. The paper then discusses the simultaneous measurement of flow rate and mole fractions by flowmeter combinations: an ultrasonic flowmeter and a venturi meter, an ultrasonic flowmeter and a laminar flowmeter. Experiments are conducted for a mixture of argon and air. When a venturi meter and a laminar flowmeter are used, the equations to evaluate the gas mixture ratio become an ill-conditioned system, and hence the evaluated mixture ratio shows a considerable error. On the other hand, the combination of an ultrasonic flowmeter and a laminar flowmeter detects the gas mixture ratio with proper accuracy.

  14. An environmental safe gas mixture for resistive plate chambers operated at low pressure

    NASA Astrophysics Data System (ADS)

    Abbrescia, M.; Bisceglie, E.; Iaselli, G.; Natali, S.; Pugliese, G.; Romano, F.

    A detailed study of the performance of resistive plate chambers, operated in streamer mode and filled with ozone safe gas mixtures, is reported; efficiency, time resolution, strip multiplicity, etc., have been measured both at atmospheric and at low pressure, to simulate a possible use of these detectors at high altitude.

  15. Thermal neutrons registration by xenon gamma-ray detector

    NASA Astrophysics Data System (ADS)

    Shustov, A. E.; Chernysheva, I. V.; Dmitrenko, V. V.; Dukhvalov, A. G.; Krivova, K. V.; Novikov, A. S.; Petrenko, D. V.; Vlasik, K. F.; Ulin, S. E.; Uteshev, Z. M.

    2016-02-01

    Experimental results of thermal neutrons detection by high pressure xenon gamma- ray spectrometers are presented. The study was performed with two devices with sensitive volumes of 0.2 and 2 litters filled with compressed mixture of xenon and hydrogen without neutron-capture additives. Spectra from Pu-Be neutron source were acquired using both detectors. Count rates of the most intensive prompt neutron-capture gamma-ray lines of xenon isotopes were calculated in order to estimate thermal neutrons efficiency registration for each spectrometer.

  16. Recent developments in parallel-grid, gas-scintillation proportional counters

    NASA Technical Reports Server (NTRS)

    Anderson, D. F.; Ku, W.; Mitchell, D. D.; Novick, R.; Wolff, R. S.

    1977-01-01

    The problems of developing large-area, gas-scintillation proportional counters with high resolution are considered. It is found that simple large-area, parallel-grid proportional counters suffer from a variation in gain over the counter window. Some success has been achieved in overcoming this problem by focusing the charge cloud as it drifts into the multiplication region. Measurements are reported for various mixtures of argon and xenon as well as pure xenon.

  17. New syntheses of xenon hexafluoride (XeF sub 6 ) and xenon tetrafluoride (XeF sub 4 )

    SciTech Connect

    Nielsen, J.B.; Kinkead, S.A.; Purson, J.D.; Eller, P.G. )

    1990-05-02

    High yield methods for preparing high-purity XeF{sub 6} and XeF{sub 4} at relatively low pressures are described. A hot wire reactor was used for the preparation of XeF{sub 6} by the direct reaction of xenon with fluorine at low pressures and high filament temperatures. Xenon tetrafluoride was prepared in quantitative yield and very high purity at low pressure and temperature by the reaction of O{sub 2}F{sub 2} with xenon. The reaction initially converts all the xenon to a mixture of XeF{sub 2} and XeF{sub 4}, and prolonged exposure of this mixture of O{sub 2}F{sub 2} further fluorinates the remaining Xe(II) to Xe(IV).

  18. Ignition of a combustible gas mixture by a high-current electric discharge in a closed volume

    SciTech Connect

    Berezhetskaya, N. K.; Gritsinin, S. I.; Kop'ev, V. A.; Kossyi, I. A.; Kuleshov, P. S.; Popov, N. A.; Starik, A. M.; Tarasova, N. M.

    2009-06-15

    Results are presented from experimental studies and numerical calculations of the ignition of a stoichiometric CH{sub 4}: O{sub 2} gas mixture by a high-current gliding discharge. It is shown that this type of discharge generates an axially propagating thermal wave (precursor) that penetrates into the gas medium and leads to fast gas heating. This process is followed by an almost simultaneous ignition of the gas mixture over the entire reactor volume.

  19. Plasma chemistry of NO in complex gas mixtures excited with a surfatron launcher.

    PubMed

    Hueso, J L; González-Elipe, A R; Cotrino, J; Caballero, A

    2005-06-01

    The plasma chemistry of NO has been investigated in gas mixtures with oxygen and/or hydrocarbon and Ar as carrier gas. Surface wave discharges operating at microwave frequencies have been used for this study. The different plasma reactions have been analyzed for a pressure range between 30 and 75 Torr. Differences in product concentration and/or reaction yields smaller than 10% were found as a function of this parameter. The following gas mixtures have been considered for investigation: Ar/NO, Ar/NO/O2, Ar/NO/CH4, Ar/CH4/O2, Ar/NO/CH4/O2. It is found that NO decomposes into N2 and O2, whereas other products such as CO, H2, and H2O are also formed when CH4 and O2 are present in the reaction mixture. Depending on the working conditions, other minority products such as HCN, CO2, and C2 or higher hydrocarbons have been also detected. The reaction of an Ar/NO plasma with deposits of solid carbon has also been studied. The experiments have provided useful information with respect to the possible removal of soot particles by this type of plasma. It has been shown that carbon deposits are progressively burned off by interaction with the plasma, and practically 100% decomposition of NO was found. Plasma intermediate species have been studied by optical emission spectroscopy (OES). Bands and/or peaks due to N2*, NO*, OH*, C2*, CN*, CH*, or H* were detected with different relative intensities depending on the gas mixture. From the analysis of both the reaction products and efficiency and the type of intermediate species detected by OES, different plasma reactions and processes are proposed to describe the plasma chemistry of NO in each particular mixture of gases. The results obtained provide interesting insights about the plasma removal of NO in real gas exhausts. PMID:16833840

  20. HXeOBr in a xenon matrix

    SciTech Connect

    Khriachtchev, Leonid; Tapio, Salla; Domanskaya, Alexandra V.; Raesaenen, Markku; Isokoski, Karoliina; Lundell, Jan

    2011-03-28

    We report on a new noble-gas molecule HXeOBr prepared in a low-temperature xenon matrix from the HBr and N{sub 2}O precursors by UV photolysis and thermal annealing. This molecule is assigned with the help of deuteration experiments and ab initio calculations including anharmonic methods. The H-Xe stretching frequency of HXeOBr is observed at 1634 cm{sup -1}, which is larger by 56 cm{sup -1} than the frequency of HXeOH identified previously. The experiments show a higher thermal stability of HXeOBr molecules in a xenon matrix compared to HXeOH.

  1. Full-spectrum k-distribution look-up table for nonhomogeneous gas-soot mixtures

    NASA Astrophysics Data System (ADS)

    Wang, Chaojun; Modest, Michael F.; He, Boshu

    2016-06-01

    Full-spectrum k-distribution (FSK) look-up tables provide great accuracy combined with outstanding numerical efficiency for the evaluation of radiative transfer in nonhomogeneous gaseous media. However, previously published tables cannot be used for gas-soot mixtures that are found in most combustion scenarios since it is impossible to assemble k-distributions for a gas mixed with nongray absorbing particles from gas-only full-spectrum k-distributions. Consequently, a new FSK look-up table has been constructed by optimizing the previous table recently published by the authors and then adding one soot volume fraction to this optimized table. Two steps comprise the optimization scheme: (1) direct calculation of the nongray stretching factors (a-values) using the k-distributions (k-values) rather than tabulating them; (2) deletion of unnecessary mole fractions at many thermodynamic states. Results show that after optimization, the size of the new table is reduced from 5 GB (including the k-values and the a-values for gases only) to 3.2 GB (including the k-values for both gases and soot) while both accuracy and efficiency remain the same. Two scaled flames are used to validate the new table. It is shown that the new table gives results of excellent accuracy for those benchmark results together with cheap computational cost for both gas mixtures and gas-soot mixtures.

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

    DOEpatents

    Winnick, Jack

    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.

  3. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

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

    1988-06-28

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  4. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, Loucas G.; Hunter, Scott R.

    1990-01-01

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc.

  5. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

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

    1990-06-26

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  6. Transport Properties of a Rarefied Ch4-N2 Gas Mixture

    NASA Astrophysics Data System (ADS)

    Fokin, L. R.; Kalashnikov, A. N.

    2016-01-01

    The area of application of the rarefied neutral methane-nitrogen gas mixture is considered. Experimental data on the transport properties of this mixture and its components were analyzed and generalized on the basis of molecular-kinetic theory relations with the use of the potentials of pair uniform and cross interactions of CH4 and N2 molecules. The parameters of three spherical symmetric three-parameter m-6 Lennard-Jones interaction potentials with a repulsive branch of varying rigidity were determined with the use of the nonlinear weight method of least squares. Tables of reference data on the viscosity of the indicated mixture and the coefficients of interdiffusion of its components were calculated for the concentration range 0-1 at temperatures 100-1150 K. Estimates of the confidential errors in determining the properties of this mixture have been made with the use of the error matrix of parameters of the indicated potentials. The results of calculations were compared with the corresponding reference data obtained earlier for the CH4-N2 gas mixture.

  7. Methane Replacement in Natural Gas Hydrate Sediments with CO2 and a CO2/N2 Gas Mixture

    NASA Astrophysics Data System (ADS)

    Park, S.; Koh, D.; Kang, H.; Lee, J.; Kim, S.; Lee, H.

    2012-12-01

    The direct recovery of methane from massive methane hydrates, artificial MH-bearing clays, and natural MH-bearing sediments is demonstrated, using either CO2 or a CO2/N2 gas mixture (20 mol% of CO2 and 80 mol% of N2, reproducing flue gas from a power plant) for methane replacement in complex marine systems. Natural gas hydrates (NGHs) can be converted into CO2 hydrate by a swapping mechanism. The overall process provides a dual purpose of sustainable energy-source exploitation and greenhouse-gas sequestration. Thus far, scant attention has been paid to the clay portion in deep-sea gas hydrate sediment, despite the fact that these materials are capable of storing a tremendous amount of NGHs. The clay particles have a peculiar structure that makes the behavior of NGHs very different from that of pure MHs. In this study, we pull out methane from intercalated methane hydrates in a clay interlayer using CO2 and a CO2/N2 gas mixture. The results of this study can contribute to the understanding of physicochemical background required for large-scale NGH production under the seabed.

  8. Monte Carlo Simulation of Electron Swarm Parameters in the SF6/CF4 Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Liu, Xueli; Xiao, Dengming

    2007-04-01

    We use a binary gas mixture Monte Carlo simulation model to calculate the electron transport parameters in SF6/CF4 mixtures in uniform electric fields. Electron collision cross section sets are assembled on the basis of the critical survey of Christophorou et al. [J. Phys. Chem. Ref. Data 25 (1996) 1341] for CF4 and Itoh et al. [J. Phys. D 21 (1988) 922] for SF6. The electron swarm parameters studied here are electron drift velocity, effective ionization coefficient and the ratio of longitudinal diffusion coefficient to mobility for the density-reduced electric field strength (E/N) in the range of 140? E/N? 600 Td (1 Td = 10-17 V cm2); the SF6 contents in the gas mixtures are 0, 20, 50, and 100%. The differences between the present calculated and measured values of Urquijo et al. [J. Phys. D 36 (2003) 3132] do not exceed the overall measured uncertainties for the parameters. To our knowledge, only Urquijo et al. [J. Phys. D 36 (2003) 3132] have measured the electron swarm parameters in SF6/CF4 gas mixtures by a pulsed Townsend technique; however, simulation results have scarcely been reported.

  9. Systematic gas gain measurements and Penning energy transfer rates in Ne - CO2 mixtures

    NASA Astrophysics Data System (ADS)

    Şahin, Ö.; Kowalski, T. Z.; Veenhof, R.

    2016-01-01

    In Ne - CO2 mixtures, excitation energy of Ne atom can be used to ionize CO2 molecule by the mechanisms called Penning transfers. In the present work, we have measured the gas gain systematically in various Ne - CO2 mixtures (Ne + 0.6 - 60% CO2) at 0.4, 0.8, 1.2, 1.8 atm. The experimental data have been fitted to investigate the Penning energy transfer rates and the secondary processes playing a role in avalanche formations.

  10. Second law of thermodynamics in volume diffusion hydrodynamics in multicomponent gas mixtures

    NASA Astrophysics Data System (ADS)

    Dadzie, S. Kokou

    2012-10-01

    We presented the thermodynamic structure of a new continuum flow model for multicomponent gas mixtures. The continuum model is based on a volume diffusion concept involving specific species. It is independent of the observer's reference frame and enables a straightforward tracking of a selected species within a mixture composed of a large number of constituents. A method to derive the second law and constitutive equations accompanying the model is presented. Using the configuration of a rotating fluid we illustrated an example of non-classical flow physics predicted by new contributions in the entropy and constitutive equations.

  11. Thermophysical properties of CF4/O2 and SF6/O2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Damyanova, M.; Hohm, U.; Balabanova, E.; Barton, D.

    2016-03-01

    Fitting formulae are presented for the calculation of the second interaction virial coefficients, mixture viscosities and binary diffusion coefficients for CF4/O2 and SF6/O2 gas mixtures in the temperature range between 200 K and 1000 K. The data recommended are obtained from the isotropic (n-6) Lennard-Jones intermolecular interaction potentials of the pure substances by using the Hohm-Zarkova-Damyanova mixing rules. In general, a good agreement is observed between our results and the experimental and theoretical data found in the literature.

  12. 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.

  13. 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

  14. 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

  15. Fundamental equations of a mixture of gas and small spherical solid particles from simple kinetic theory.

    NASA Technical Reports Server (NTRS)

    Pai, S. I.

    1973-01-01

    The fundamental equations of a mixture of a gas and pseudofluid of small spherical solid particles are derived from the Boltzmann equation of two-fluid theory. The distribution function of the gas molecules is defined in the same manner as in the ordinary kinetic theory of gases, but the distribution function for the solid particles is different from that of the gas molecules, because it is necessary to take into account the different size and physical properties of solid particles. In the proposed simple kinetic theory, two additional parameters are introduced: one is the radius of the spheres and the other is the instantaneous temperature of the solid particles in the distribution of the solid particles. The Boltzmann equation for each species of the mixture is formally written, and the transfer equations of these Boltzmann equations are derived and compared to the well-known fundamental equations of the mixture of a gas and small solid particles from continuum theory. The equations obtained reveal some insight into various terms in the fundamental equations. For instance, the partial pressure of the pseudofluid of solid particles is not negligible if the volume fraction of solid particles is not negligible as in the case of lunar ash flow.

  16. Methods to produce calibration mixtures for anesthetic gas monitors and how to perform volumetric calculations on anesthetic gases.

    PubMed

    Christensen, P L; Nielsen, J; Kann, T

    1992-10-01

    A simple procedure for making calibration mixtures of oxygen and the anesthetic gases isoflurane, enflurane, and halothane is described. One to ten grams of the anesthetic substance is evaporated in a closed, 11,361-cc glass bottle filled with oxygen gas at atmospheric pressure. The carefully mixed gas is used to calibrate anesthetic gas monitors. By comparison of calculated and measured volumetric results it is shown that at atmospheric conditions the volumetric behavior of anesthetic gas mixtures can be described with reasonable accuracy using the ideal gas law. A procedure is described for calculating the deviation from ideal gas behavior in cases in which this is needed. PMID:1453187

  17. Intermolecular polarizabilities in H{sub 2}-rare-gas mixtures (H{sub 2}–He, Ne, Ar, Kr, Xe): Insight from collisional isotropic spectral properties

    SciTech Connect

    Głaz, Waldemar Bancewicz, Tadeusz; Godet, Jean-Luc; Gustafsson, Magnus; Maroulis, George; Haskopoulos, Anastasios

    2014-08-21

    The report presents results of theoretical and numerical analysis of the electrical properties related to the isotropic part of the polarizability induced by interactions within compounds built up of a hydrogen H{sub 2} molecule and a set of noble gas atoms, Rg, ranging from the least massive helium up to the heaviest xenon perturber. The Cartesian components of the collisional polarizabilities of the H{sub 2}–Rg systems are found by means of the quantum chemistry methods and their dependence on the intermolecular distance is determined. On the basis of these data, the spherical, symmetry adapted components of the trace polarizability are derived in order to provide data sets that are convenient for evaluating collisional spectral profiles of the isotropic polarized part of light scattered by the H{sub 2}–Rg mixtures. Three independent methods of numerical computing of the spectral intensities are applied at room temperature (295 K). The properties of the roto-translational profiles obtained are discussed in order to determine the role played by contributions corresponding to each of the symmetry adapted parts of the trace polarizability. By spreading the analysis over the collection of the H{sub 2}–Rg systems, evolution of the spectral properties with the growing masses of the supermolecular compounds can be observed.

  18. Experimental study and kinetics modeling of gas hydrate formation of methane-ethane mixture

    NASA Astrophysics Data System (ADS)

    Naeiji, Parisa; Varaminian, Farshad

    2013-09-01

    In this study, gas hydrate formation kinetics of methane and ethane binary mixtures has been studied and data of mixed methane-ethane hydrate formation at 0.1, 0.2, 0.3, 0.5, 0.68, 0.8, and 0.9 mole fractions of methane and at a temperature of 277.15 K and an initial pressure of approximately 3.6 MPa were collected. The thermodynamic natural path was used for modeling the hydrate formation rate in a constant volume process. The results show that there is good agreement between model prediction and experimental data, with an average error of 0.9%. It was observed that the values of these parameters are dependent on the concentration of components in the mixtures. The results indicate that this model can predict constant volume experimental data of binary mixture hydrate.

  19. Pulsative corona from free spherical conducting particles in SF{sub 6}/gas mixtures

    SciTech Connect

    Mufti, A.H.; Malik, N.H.

    1996-12-31

    Pulsative corona discharges from free spherical shaped conducting particles are investigated experimentally using SF{sub 6} and its mixtures with nitrogen N{sub 2}, perfluorocarbon C{sub 8}F{sub 16}O triethylamine (C{sub 2}H{sub 5}){sub 3}N and freon C{sub 2}Cl{sub 3}F{sub 3} gases. Corona inception, particle lift-off and breakdown voltages as well as charge-voltage (q-v) characteristics were determined in these mixtures. The results show that corona characteristics are affected by particle diameter and gas mixtures. Generally, small percentages of these additive gases results in reduced corona charge levels. The particle movement is also observed and reported in this paper.

  20. Statistical mechanics and molecular simulation of adsorption of ternary gas mixtures in nanoporous materials

    NASA Astrophysics Data System (ADS)

    Xu, Lifang; Tsotsis, Theodore T.; Sahimi, Muhammad

    2001-04-01

    We report the results of extensive equilibrium molecular dynamics simulation of adsorption of ternary gas mixtures in a class of model nanoporous materials, namely, carbon molecular sieve membranes (CMSMs), which are being utilized for separation of gas mixtures. We use a novel three-dimensional molecular pore network model for CMSMs based on Voronoi tessellation of the simulation cell. The simulations with such a model allow us to investigate the effect of the morphology of the pore space, i.e., its pore size distribution and pore connectivity, on the adsorption isotherms. We also extend a statistical mechanical theory of adsorption of single gases and their binary mixtures, recently developed by us, to ternary mixtures and use the results of the molecular simulations to test its accuracy. The theory is shown to provide very accurate predictions for the simulation results over wide ranges of the temperature and porosity of the membrane. The performance of the theory is also compared with that of another theory of adsorption based on a virial expansion.

  1. 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 ~500 for FAIMS/IMS separations, and ~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.

  2. A new concept in the design of pressure-swing adsorption processes for multicomponent gas mixtures

    SciTech Connect

    Dong, F.; Lou, H.; Kodama, Akio; Goto, Motonobu; Hirose, Tsutomu

    1999-01-01

    This paper discusses a new concept in pressure-swing adsorption (PSA) process design for the separation of multicomponent gas mixtures. A more compact process design is achievable by incorporating two or more different adsorbents into a single PSA column. An example, used to illustrate the new concept, involved the separation of a ternary gas mixture containing carbon dioxide, methane, and nitrogen. With the new design, only two pairs of adsorption columns were required in place of the usual three. Feed was introduced at midcolumn of unit 1 and a midcolumn side stream from unit 2 supplied intermediate product. Three different adsorbents were required for the example separation. The process was simulated using a simple mathematical model which demonstrated that the new design gave a performance comparable to that of the original integrated process.

  3. Cryotrapping assisted mass spectrometry for the analysis of complex gas mixtures

    SciTech Connect

    Ferreira, Jose A.; Tabares, Francisco L.

    2007-03-15

    A simple method is described for the unambiguous identification of the individual components in a gas mixture showing strong overlapping of their mass spectrometric cracking patterns. The method, herein referred to as cryotrapping assisted mass spectrometry, takes advantage of the different vapor pressure values of the individual components at low temperature (78 K for liquid nitrogen traps), and thus of the different depletion efficiencies and outgassing patterns during the fast cooling and slow warming up of the trap, respectively. Examples of the use of this technique for gas mixtures with application to plasma enhanced chemical vapor deposition of carbon and carbon-nitrogen hard films are shown. Detection of traces of specific C{sub 3} hydrocarbons (<50 ppm of initial methane) in methane/hydrogen plasmas and the possible trapping of thermally unstable C-N compounds in N{sub 2} containing deposition plasmas are addressed as representative examples of specific applications of the technique.

  4. 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.

  5. 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.

  6. Amplification and scintillation properties of oxygen-rich gas mixtures for optical-TPC applications

    NASA Astrophysics Data System (ADS)

    Weissman, L.; Gai, M.; Breskin, A.; Chechik, R.; Dangendorf, V.; Tittelmeier, K.; Weller, H. R.

    2006-05-01

    We studied electron amplification and light emission from avalanches in oxygen-containing gas mixtures. The mixtures investigated in this work included, among others, CO2 and N2O mixed with Triethylamine (TEA) or N2. Double-Step Parallel Gap (DSPG) multipliers and THick Gas Electron Multipliers (THGEM) were investigated. High light yields were measured from CO2 + N2 and CO2 + TEA, though with different emission spectra. We observed the characteristic wave-length emission of N2 and of TEA and used a polymer wave-length shifter to convert TEA UV-light into the visible spectrum. The results of these measurements indicate the applicability of optical recording of ionizing tracks in a TPC target-detector designed to study the cross-sections of the 16O(γ, α)12C reaction, a central problem in nuclear astrophysics.

  7. An homeopathic cure to pure Xenon large diffusion

    NASA Astrophysics Data System (ADS)

    Azevedo, C. D. R.; Fernandes, L. M. P.; Freitas, E. D. C.; Gonzalez-Diaz, D.; Monrabal, F.; Monteiro, C. M. B.; Dos Santos, J. M. F.; Veloso, J. F. C. A.; Gomez-Cadenas, J. J.

    2016-02-01

    The NEXT neutrinoless double beta decay (ββ0ν) experiment will use a high-pressure gas electroluminescence-based TPC to search for the decay of Xe-136. One of the main advantages of this technology is the possibility to reconstruct the topology of events with energies close to Qββ. The rejection potential associated to the topology reconstruction is limited by our capacity to properly reconstruct the original path of the electrons in the gas. This reconstruction is limited by different factors that include the geometry of the detector, the density of the sensors in the tracking plane and the separation among them, etc. Ultimately, the resolution is limited by the physics of electron diffusion in the gas. In this paper we present a series of molecular additives that can be used in Xenon gas at very low partial pressure to reduce both longitudinal and transverse diffusion. We will show the results of different Monte-Carlo simulations of electron transport in the gas mixtures from wich we have extracted the value of some important parameters like diffusion, drift velocity and light yields. These results show that there is a series of candidates that can reduce diffusion without affecting the energy resolution of the detector and they should be studied experimentally. A comparison with preliminary results from such an ongoing experimental effort is given.

  8. 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.

  9. 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.

  10. Process and catalyst for converting synthesis gas to liquid hydrocarbon mixture

    DOEpatents

    Rao, V. Udaya S.; Gormley, Robert J.

    1987-01-01

    Synthesis gas containing CO and H.sub.2 is converted to a high-octane hydrocarbon liquid in the gasoline boiling point range by bringing the gas into contact with a heterogeneous catalyst including, in physical mixture, a zeolite molecular sieve, cobalt at 6-20% by weight, and thoria at 0.5-3.9% by weight. The contacting occurs at a temperature of 250.degree.-300.degree. C., and a pressure of 10-30 atmospheres. The conditions can be selected to form a major portion of the hydrocarbon product in the gasoline boiling range with a research octane of more than 80 and less than 10% by weight aromatics.

  11. Sterilization of Bacillus subtilis Spores Using an Atmospheric Plasma Jet with Argon and Oxygen Mixture Gas

    NASA Astrophysics Data System (ADS)

    Shen, Jie; Cheng, Cheng; Fang, Shidong; Xie, Hongbing; Lan, Yan; Ni, Guohua; Meng, Yuedong; Luo, Jiarong; Wang, Xiangke

    2012-03-01

    To determine an efficient sterilization mechanism, Bacillus subtilis spore samples were exposed to an atmospheric plasma jet. By using argon/oxygen mixture gas, the decimal reduction value was reduced from 60 s (using argon gas) to 10 s. More dramatically, after 5 min treatment, the colony-forming unit (CFU) was reduced by six orders. To understand the underlying mechanism of the efficient sterilization by plasma, the contributions from heat, UV radiation, charged particles, ozone, and reactive oxygen radicals were distinguished in this work, showing that charged particles and ozone were the main killing factors. The shape changes of the spores were also discussed.

  12. 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.

  13. Equilibrium Theory for Adiabatic Desorption of Bulk Binary Gas Mixtures by Purge

    SciTech Connect

    Sircar, S.; Kumar, R.

    1985-04-01

    A local equilibrium theory for adiabatic desorption of bulk binary gas mixtures by isobaric purge is developed. The model is used for evaluating the effect of adsorption selectivity, the strength of sorption, and the purge gas composition on the desorption process. Examples of the desorption of CO/sub 2/ from mixtures with CH/sub 4/, N/sub 2/, and H/sub 2/ are considered. Analytical equations to describe isothermal desorption of binary Langmuir adsorbates are derived. Desorption profiles obtained from isothermal and adiabatic models are compared. It is demonstrated that (a) desorption of a more strongly adsorbed species (component 1) by purging with a less strongly species (component 2) is more efficient when component 1 is less selectively adsorbed; (b) an adsorbent which exhibits higher adsorption capacity and selectivity for component 1 also requires more purge gas to clean the column and thus the adsorbent may not be preferred for separation by PSA process; (c) composition of the purge gas is important only to determine the level of residual component 1 at the end of the purge step; and (d) assumption of column isothermality during the purge process can severely underestimate the quantity of the purge gas requirement of an adiabatic column.

  14. Scalability Study of Solid Xenon

    SciTech Connect

    Yoo, J.; Cease, H.; Jaskierny, W. F.; Markley, D.; Pahlka, R. B.; Balakishiyeva, D.; Saab, T.; Filipenko, M.

    2015-04-24

    We report a demonstration of the scalability of optically transparent xenon in the solid phase for use as a particle detector above a kilogram scale. We employed a cryostat cooled by liquid nitrogen combined with a xenon purification and chiller system. A modified {\\it Bridgeman's technique} reproduces a large scale optically transparent solid xenon.

  15. Plasma nitriding using high H2 content gas mixtures for a cavitation erosion resistant steel

    NASA Astrophysics Data System (ADS)

    Allenstein, A. N.; Lepienski, C. M.; Buschinelli, A. J. A.; Brunatto, S. F.

    2013-07-01

    Plasma nitriding using high H2 content gas mixtures in CA-6NM martensitic stainless steel was studied in the present work. Nitriding was performed in H2 + N2 gas mixtures for 5, 10 and 20% N2, in volume, at 773 K (500 °C), during 2 h. Changes in the surface morphology and nitrided layer constitution were characterized by SEM, XRD, roughness analysis, and nanoindentation technique. Cavitation erosion behavior of the nitrided samples was also investigated by means of a 20 kHz ultrasonic vibrator. The study was emphasized for the three first cavitation stages (incubation, acceleration, and maximum erosion rate stage) of the cumulative erosion-time curve. Results indicate that the gas mixture nitrogen content strongly influences the phases' formation and its distribution on the nitrided layer. Better cavitation erosion resistance which was attributed to the finer and more homogeneous distribution of the nitrided layer phases was verified for samples treated at 5% N2. Otherwise, worse cavitation erosion behavior for samples nitrided at 20% N2 is supposed to be due to the formation of multiphase compound layer constituted by Fe4N + Fe2-3N + CrN, which can infer residual stress in treated surface.

  16. A general stagnation-point convective heating equation for arbitrary gas mixtures

    NASA Technical Reports Server (NTRS)

    Sutton, K.; Graves, R. A., Jr.

    1971-01-01

    The stagnation-point convective heat transfer to an axisymmetric blunt body for arbitrary gases in chemical equilibrium was investigated. The gases considered were base gases of nitrogen, oxygen, hydrogen, helium, neon, argon, carbon dioxide, ammonia, and methane and 22 gas mixtures composed of the base gases. Enthalpies ranged from 2.3 to 116.2 MJ/kg, pressures ranged from 0.001 to 100 atmospheres, and the wall temperatures were 300 and 1111 K. A general equation for the stagnation-point convective heat transfer in base gases and gas mixtures was derived and is a function of the mass fraction, the molecular weight, and a transport parameter of the base gases. The relation compares well with present boundary-layer computer results and with other analytical and experimental results. In addition, the analysis verified that the convective heat transfer in gas mixtures can be determined from a summation relation involving the heat transfer coefficients of the base gases. The basic technique developed for the prediction of stagnation-point convective heating to an axisymmetric blunt body could be applied to other heat transfer problems.

  17. Carbothermal Reduction of Quartz in Methane-Hydrogen-Argon Gas Mixture

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Zhang, Guangqing; Tang, Kai; Ostrovski, Oleg; Tronstad, Ragnar

    2015-10-01

    Synthesis of silicon carbide (SiC) by carbothermal reduction of quartz in a CH4-H2-Ar gas mixture was investigated in a laboratory fixed-bed reactor in the temperature range of 1573 K to 1823 K (1300 °C to 1550 °C). The reduction process was monitored by an infrared gas analyser, and the reduction products were characterized by LECO, XRD, and SEM. A mixture of quartz-graphite powders with C/SiO2 molar ratio of 2 was pressed into pellets and used for reduction experiments. The reduction was completed within 2 hours under the conditions of temperature at or above 1773 K (1500 °C), methane content of 0.5 to 2 vol pct, and hydrogen content ≥70 vol pct. Methane partially substituted carbon as a reductant in the SiC synthesis and enhanced the reduction kinetics significantly. An increase in the methane content above 2 vol pct caused excessive carbon deposition which had a detrimental effect on the reaction rate. Hydrogen content in the gas mixture above 70 vol pct effectively suppressed the cracking of methane.

  18. 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.

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

    DOEpatents

    Aines, Roger D.; Bourcier, William L.

    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.

  20. 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.

  1. Ionization and scintillation of nuclear recoils in gaseous xenon

    NASA Astrophysics Data System (ADS)

    Renner, J.; Gehman, V. M.; Goldschmidt, A.; Matis, H. S.; Miller, T.; Nakajima, Y.; Nygren, D.; Oliveira, C. A. B.; Shuman, D.; Álvarez, V.; Borges, F. I. G.; Cárcel, S.; Castel, J.; Cebrián, S.; Cervera, A.; Conde, C. A. N.; Dafni, T.; Dias, T. H. V. T.; Díaz, J.; Esteve, R.; Evtoukhovitch, P.; Fernandes, L. M. P.; Ferrario, P.; Ferreira, A. L.; Freitas, E. D. C.; Gil, A.; Gómez, H.; Gómez-Cadenas, J. J.; González-Díaz, D.; Gutiérrez, R. M.; Hauptman, J.; Hernando Morata, J. A.; Herrera, D. C.; Iguaz, F. J.; 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.; Martínez, A.; Moiseenko, A.; Monrabal, F.; Monserrate, M.; Monteiro, C. M. B.; Mora, F. J.; Moutinho, L. M.; Muñoz Vidal, J.; Natal da Luz, H.; Navarro, G.; Nebot-Guinot, M.; Palma, R.; Pérez, J.; Pérez Aparicio, J. L.; Ripoll, L.; Rodríguez, A.; Rodríguez, J.; Santos, F. P.; dos Santos, J. M. F.; Seguí, L.; Serra, L.; Simón, A.; Sofka, C.; Sorel, M.; Toledo, J. F.; Tomás, A.; Torrent, J.; Tsamalaidze, Z.; Veloso, J. F. C. A.; Villar, J. A.; Webb, R. C.; White, J.; Yahlali, N.

    2015-09-01

    Ionization and scintillation produced by nuclear recoils in gaseous xenon at approximately 14 bar have been simultaneously observed in an electroluminescent time projection chamber. Neutrons from radioisotope α-Be neutron sources were used to induce xenon nuclear recoils, and the observed recoil spectra were compared to a detailed Monte Carlo employing estimated ionization and scintillation yields for nuclear recoils. The ability to discriminate between electronic and nuclear recoils using the ratio of ionization to primary scintillation is demonstrated. These results encourage further investigation on the use of xenon in the gas phase as a detector medium in dark matter direct detection experiments.

  2. Theoretical and experimental analysis of a multiphase screw pump, handling gas-liquid mixtures with very high gas volume fractions

    SciTech Connect

    Raebiger, K.; Maksoud, T.M.A.; Ward, J.; Hausmann, G.

    2008-09-15

    In the investigation of the pumping behaviour of multiphase screw pumps, handling gas-liquid mixtures with very high gas volume fractions, theoretical and experimental analyses were performed. A new theoretical screw pump model was developed, which calculates the time-dependent conditions inside the several chambers of a screw pump as well as the exchange of mass and energy between these chambers. By means of the performed experimental analysis, the screw pump model was verified, especially at very high gas volume fractions from 90% to 99%. The experiments, which were conducted with the reference fluids water and air, can be divided mainly into the determination of the steady state pumping behaviour on the one hand and into the analysis of selected transient operating conditions on the other hand, whereas the visualisation of the leakage flows through the circumferential gaps was rounded off the experimental analysis. (author)

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

    NASA Astrophysics Data System (ADS)

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

    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 that the J-T cycle is an efficient application of mixed gas working fluids, being very similar to a vapor-compression cycle utilized in household refrigerants. The simplicity and viability of a J-T design and the associated minimal heat losses compensate for theoretical efficiency ratio of Stirling-type machines. Simultaneously, the J-T machines are never restricted in terms of output power and contain no moving parts in the cold zone resulting in minimal vibration during operation. The effective cooling of these systems allows parallel cooling of multiple objects. Finally in long-life system designs these cryocooler systems are feasibly coupled with phase-transition thermal storage accumulators. The application of such J-T systems is especially efficient under space conditions, due to the fact that there is an option to use at low temperatures a radiation release unit for the outlet of compression heat and for preliminary cooling of the system. This is not possible for terrestrial applications. Particularly, obtaining the -10 to 100 (C temperature range is feasible through the use of low As/(( - coefficient coatings; shade screens; or radiator unit orientations. Computational and experimental research has provided us high efficiency gas-mixture J-T cryocooler results between 60 to 100K cooling temperatures. We have actual space systems which were tested and operated for 80-90 K with efficiencies of 20 to 25 W/W. The authors of this research have studied various gas mixtures as candidates for use with simple J-T single contour J-T systems. We have seen resultant reduction of energy consumption by 2-3 times and decreases in temperatures from the 30-60( C range to -10 to 10( C range. We have also seen a dramatic reduction in the working pressure and the P/P pressure ratios within the cycle. We have gradually evolved into the application of simpler and more reliable working mixtures and employed more reliable single-stage compressors. In addition, the use of J-T contour gas mixtures for pre-cooling down to 35-40 K temperatures results in higher efficiency 2-stage J-T cryocoolers with similar overall results to the single stage systems.

  4. Regularized moment equations for binary gas mixtures: Derivation and linear analysis

    NASA Astrophysics Data System (ADS)

    Gupta, Vinay Kumar; Struchtrup, Henning; Torrilhon, Manuel

    2016-04-01

    The applicability of the order of magnitude method [H. Struchtrup, "Stable transport equations for rarefied gases at high orders in the Knudsen number," Phys. Fluids 16, 3921-3934 (2004)] is extended to binary gas mixtures in order to derive various sets of equations—having minimum number of moments at a given order of accuracy in the Knudsen number—for binary mixtures of monatomic-inert-ideal gases interacting with the Maxwell interaction potential. For simplicity, the equations are derived in the linear regime up to third order accuracy in the Knudsen number. At zeroth order, the method produces the Euler equations; at first order, it results into the Fick, Navier-Stokes, and Fourier equations; at second order, it yields a set of 17 moment equations; and at third order, it leads to the regularized 17-moment equations. The transport coefficients in the Fick, Navier-Stokes, and Fourier equations obtained through order of magnitude method are compared with those obtained through the classical Chapman-Enskog expansion method. It is established that the different temperatures of different constituents do not play a role up to second order accurate theories in the Knudsen number, whereas they do contribute to third order accurate theory in the Knudsen number. Furthermore, it is found empirically that the zeroth, first, and second order accurate equations are linearly stable for all binary gas mixtures; however, although the third order accurate regularized 17-moment equations are linearly stable for most of the mixtures, they are linearly unstable for mixtures having extreme difference in molecular masses.

  5. 10 CFR 504.7 - Prohibition against excessive use of petroleum or natural gas in mixtures-electing powerplants.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.7 Prohibition against excessive use of petroleum or natural gas... technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an alternate... natural gas, or both, in amounts exceeding the minimum amount necessary to maintain reliability...

  6. 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

    ...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.7 Prohibition against excessive use of petroleum or natural gas... technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an alternate... natural gas, or both, in amounts exceeding the minimum amount necessary to maintain reliability...

  7. Purging means and method for Xenon arc lamps

    NASA Technical Reports Server (NTRS)

    Miller, C. G. (Inventor)

    1973-01-01

    High pressure Xenon short-arc lamp with two reservoirs which are selectively connectable to the lamp's envelope is described. One reservoir contains an absorbent which will absorb both Xenon and contaminant gases such as CO2 and O2. The absorbent temperature is controlled to evacuate the envelope of both the Xenon and the contaminant gases. The temperature of the absorbent is then raised to desorb only clean Xenon while retaining the contaminant gases, thereby clearing the envelope of the contaminant gases. The second reservoir contains a gas whose specific purpose is, to remove the objectional metal film which deposits gradually on the interior surface of the lamp envelope during normal arc operation. The origin of the film is metal transferred from the cathode of the arc lamp by sputtering or other gas transfer processes.

  8. A fast iterative discrete velocity method for ternary gas mixtures flowing through long tubes

    NASA Astrophysics Data System (ADS)

    Szalmás, Lajos

    2016-03-01

    An accelerated discrete velocity method is presented for flows of three-component gas mixtures through long tubes. The gas is modeled by the McCormack linearized kinetic equation. Two diffusion equations are derived from the kinetic one. These equations are solved during the kinetic iteration by a linear algebraic approach. Test simulations are performed for flows of He-Ar-Xe mixture driven by pressure or temperature gradients in a wide range of the gas rarefaction. The accelerated method requires fewer number of iterations and smaller computational times than the non-accelerated one in the early transition, slip and near-hydrodynamic domains. The efficiency of the accelerated scheme compared to the standard one increases with increasing rarefaction parameter. The computational performance in terms of the iteration criterion is also analyzed. In typical simulations, the convergent results can be reached in approximately less than two minutes by using the new method in a wide range of the gas rarefaction on a present-day computer.

  9. Modeling of combustion wave propagation in a carbon dust/gas mixture

    SciTech Connect

    Krishenik, P.M.; Rumanov, E.N.; Shkadinskii, K.G. Inst. of Structural Macrokinetics)

    1994-12-01

    Combustion wave propagation in a carbon dust/gas mixture is studied, taking into account both radiative and conductive heat transfer. A two-temperature mathematical model is suggested for the analysis of the nonstationary processes occurring in exothermic reactions during propagation of the wave front in a carbon dust/gas mixture. Temperatures of the particles and gas are assumed to be different and radiative heat transfer is described by a diffusion approximation. Particle size is varied in the range of 10 to 20 [mu]m. In the absence of heat losses, transition from the slow conductive combustion to the fast radiative one is explosive in nature. In such a case, both the combustion wave velocity and the width of the reaction zone are enhanced by 2--3 orders of magnitude. In the presence of heat losses, the behavior of the flame front propagation is change drastically. Conductive heat losses may result in nonuniqueness of combustion. Dependent on the initiation conditions, either a slow, or fast combustion wave may be expected to be generated in the system. Radiative heat losses lead to diminished combustion wave velocities, and marginally, to the transition from fast to slow combustion. Some aspects of pulsating combustion have also been considered, such as the oscillations of combustion wave velocity and particle and gas temperatures. Instability development is studied with the suggested model.

  10. Perceptual Characterization and Analysis of Aroma Mixtures Using Gas Chromatography Recomposition-Olfactometry

    PubMed Central

    Johnson, Arielle J.; Hirson, Gregory D.; Ebeler, Susan E.

    2012-01-01

    This paper describes the design of a new instrumental technique, Gas Chromatography Recomposition-Olfactometry (GC-R), that adapts the reconstitution technique used in flavor chemistry studies by extracting volatiles from a sample by headspace solid-phase microextraction (SPME), separating the extract on a capillary GC column, and recombining individual compounds selectively as they elute off of the column into a mixture for sensory analysis (Figure 1). Using the chromatogram of a mixture as a map, the GC-R instrument allows the operator to cut apart" and recombine the components of the mixture at will, selecting compounds, peaks, or sections based on retention time to include or exclude in a reconstitution for sensory analysis. Selective recombination is accomplished with the installation of a Deans Switch directly in-line with the column, which directs compounds either to waste or to a cryotrap at the operator's discretion. This enables the creation of, for example, aroma reconstitutions incorporating all of the volatiles in a sample, including instrumentally undetectable compounds as well those present at concentrations below sensory thresholds, thus correcting for the reconstitution discrepancy" sometimes noted in flavor chemistry studies. Using only flowering lavender (Lavandula angustifola Hidcote Blue) as a source for volatiles, we used the instrument to build mixtures of subsets of lavender volatiles in-instrument and characterized their aroma qualities with a sensory panel. We showed evidence of additive, masking, and synergistic effects in these mixtures and of lavender' aroma character as an emergent property of specific mixtures. This was accomplished without the need for chemical standards, reductive aroma models, or calculation of Odor Activity Values, and is broadly applicable to any aroma or flavor. PMID:22912722

  11. On the appearance of self-oscillatory conditions of gas and gas-droplet mixture flow out of a vessel into a counterpressure medium

    NASA Astrophysics Data System (ADS)

    Timoshenko, V. I.; Galinskii, V. P.

    2013-01-01

    The present paper discusses the problem of flow of a gas and a gas-dispersion mixture out of a vessel with given pressure and stagnation temperature through a channel into a medium with a given pressure. The influence of energy and gas mass supplies distributed over the channel length, as well as of the kind of injected gas and its combustion, on the flow character is analyzed. On the basis of the analysis of the results of the numerical solution of quasi-one-dimensional dynamic equations of the gas and the gas-dispersion mixture, it has been shown that at a certain intensity of the considered actions the transition of the flow conditions from stationary to self-oscillatory ones can take place. From the viewpoint of the homogeneous and two-velocitytwo-temperature models of the gas-droplet mixture the main laws of the influence of droplet evaporation on the parameters of this transition have been elucidated.

  12. Requirements for Xenon International

    SciTech Connect

    Hayes, James C.; Ely, James H.; Haas, Derek A.; Harper, Warren W.; Heimbigner, Tom R.; Hubbard, Charles W.; Humble, Paul H.; Madison, Jill C.; Morris, Scott J.; Panisko, Mark E.; Ripplinger, Mike D.; Stewart, Timothy L.

    2015-12-30

    This document defines the requirements for the new Xenon International radioxenon system. The output of this project will be a Pacific Northwest National Laboratory (PNNL) developed prototype and a manufacturer-developed production prototype. The two prototypes are intended to be as close to matching as possible; this will be facilitated by overlapping development cycles and open communication between PNNL and the manufacturer.

  13. Requirements for Xenon International

    SciTech Connect

    Hayes, James C.; Ely, James H.

    2013-09-26

    This document defines the requirements for the new Xenon International radioxenon system. The output of this project will be a Pacific Northwest National Laboratory (PNNL) developed prototype and a manufacturer-developed production prototype. The two prototypes are intended to be as close to matching as possible; this will be facilitated by overlapping development cycles and open communication between PNNL and the manufacturer.

  14. 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.

  15. Atmospheric pressure glow discharge generated in nitrogen-methane gas mixture: PTR-MS analyzes of the exhaust gas

    NASA Astrophysics Data System (ADS)

    Torokova, Lucie; Mazankova, Vera; Krcma, Frantisek; Mason, Nigel J.; Matejcik, Stefan

    2015-07-01

    This paper reports the results of an extensive study of with the in situ mass spectrometry analysis of gaseous phase species produced by an atmospheric plasma glow discharge in N2-CH4 gas mixtures (with methane concentrations ranging from 1% to 4%). The products are studied using proton-transfer-reaction mass spectrometry (PTR-MS). HCN and CH3CN are identified as the main gaseous products. Hydrazine, methanimine, methyldiazene, ethylamine, cyclohexadiene, pyrazineacetylene, ethylene, propyne and propene are identified as minor compounds. All the detected compounds and their relative abundances are determined with respect to the experimental conditions (gas composition and applied power). The same molecules were observed by the Cassini-Huygens probe in Titan's atmosphere (which has same N2-CH4 gas mixtures). Such, experiments show that the formation of such complex organics in atmospheres containing C, N and H, like that of Titan, could be a source of prebiotic molecules. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  16. A computational investigation of the effectiveness of different shielding gas mixtures for arc welding

    NASA Astrophysics Data System (ADS)

    Murphy, A. B.; Tanaka, M.; Tashiro, S.; Sato, T.; Lowke, J. J.

    2009-06-01

    Tungsten-inert-gas welding arcs are modelled using a two-dimensional axisymmetric computational code. Both electrodes (the tungsten cathode and the metal anode workpiece) and the arc plasma are included self-consistently in the computational domain. The influence of adding helium, hydrogen and nitrogen to the argon shielding gas is investigated. It is found that addition of any of the gases increases the heat flow to and the current density at the anode. The shear stress and the arc pressure at the anode surface are increased by adding hydrogen or nitrogen or up to about 50 mol% helium, but decrease when more helium is added. It is predicted that the effect of adding any of the gases is to increase the depth of the weld pool, in agreement with the experimental evidence. The results are explained by referring to the thermodynamic and transport properties of the gas mixtures.

  17. Polymer coated quartz crystal microbalance sensors for detection of volatile organic compounds in gas mixtures.

    PubMed

    Si, Pengchao; Mortensen, John; Komolov, Alexei; Denborg, Jens; Møller, Preben Juul

    2007-08-01

    By coating different conducting polymers of thiophene and its derivatives on quartz crystal microbalance (QCM) sensor surfaces, new novel QCM gas sensors have been produced in two simple ways, which could classify testing gas samples of volatile organic compounds (VOCs) gases. Principle components analysis (PCA) has been performed based on the QCM measurement results, which shows that our QCM sensors array has very good utilizing potential on sensing both polar and low-polar/nonpolar VOC gases. The sensitivity, selectivity, reproducibility and detection limit of QCM sensors have also been discussed. Quantitative variation of sensitivity response with the increasing concentration has been studied. (PLS) analysis and prediction of concentrations of single gas in mixtures have been carried out. PMID:17683733

  18. [Fire disaster due to deflagration of a propane gas-air mixture].

    PubMed

    Nadjem, Hadi; Vogt, Susanne; Simon, Karl-Heinz; Pollak, Stefan; Geisenberger, Dorothee; Kramer, Lena; Pircher, Rebecca; Perdekampl, Markus Große; Thierauf-Emberger, Annette

    2015-01-01

    On 26 Nov 2012, a serious fire occurred at Neustadt/Black Forest in which 14 persons in a sheltered workshop died and 10 other individuals were injured. The fire was caused by the unbridled escape of propane gas due to accidental disconnection of the screw fixing between a gas bottle and a catalytic heater. Deflagration of the propane gas-air mixture set the workshop facilities on fire. In spite of partly extensive burns the fatally injured victims could be rapidly identified. The results of the fire investigations at the scene and the autopsy findings are presented. Carboxyhemoglobin concentrations ranged between 8 and 56 % and signs of fire fume inhalation were present in all cases. Three victims had eardrum ruptures due to the sudden increase in air pressure during the deflagration. PMID:26548032

  19. Additional development of large diameter carbon monofilament. [from boron, hydrogen, and methane gas mixture

    NASA Technical Reports Server (NTRS)

    Jacob, B. A.; Veltri, R. D.

    1974-01-01

    The chemical vapor process for preparing a large diameter carbon-base monofilament from a BCl3, Ch4 and H2 gas mixture with a carbon substrate fiber was studied. The effect of reactor geometry, total gas flows and deposition temperature on the tensile strength of the monofilament were investigated. It was noted that consistent results could only be obtained when the carbon substrate fiber was cleaned. The strength of the monofilament was found to depend on the highest temperature and the temperature profile of the monofilament in the reactor. The strength of monofilament produced in the dc and RF reactors were found to be similar and similar alloy compositions in the monofilament were attained when the same gas ratios were used. The tensile strength of the monofilament at 500 C was found to be 60 to 70% of the room temperature tensile strength. No degradation was noted after exposure to molten aluminum.

  20. 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.

  1. 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 β-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.

  2. 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.

  3. Strongly interacting one-dimensional quantum gas mixtures with weak p -wave interactions

    NASA Astrophysics Data System (ADS)

    Hu, Haiping; Pan, Lei; Chen, Shu

    2016-03-01

    We study one-dimensional strongly interacting quantum gas mixtures, including both the Bose-Fermi and spin-1 /2 Fermi-Fermi mixtures, with weak p -wave interaction between intracomponent fermions, and demonstrate that the weak p -wave interaction cannot be omitted in the strong interaction region where the strength of p -wave interaction is comparable with the inverse of the strength of strongly repulsive s -wave interaction. While the total density distribution is not sensitive to the weak p -wave interaction, we find that the p -wave interaction plays an important role in determining the species-dependent (or spin-dependent) density distributions and produces significant physical effects on the low-energy spin dynamics. We also derive effective spin-exchange models for strongly interacting quantum gas mixtures with weak p -wave interaction, which indicate that a quantum phase transition from an antiferromagnetic state to a ferromagnetic state can be induced by tuning the relative strengths of intracomponent and intercomponent interactions.

  4. Measurement of adiabatic burning velocity in natural gas-like mixtures

    SciTech Connect

    Ratna Kishore, V.; Duhan, Nipun; Ravi, M.R.; Ray, Anjan

    2008-10-15

    Experimental measurements of the adiabatic burning velocities were carried out for natural gas-like mixtures burning in air over a range of equivalence ratios at atmospheric pressure. Effect of CO{sub 2} dilution up to 60%, N{sub 2} dilution up to 40% and 25% enrichment of ethane on burning velocity of methane-air flames were studied. Heat flux method with setup similar to that of [K.J. Bosschaart, L.P.H. de Goey, Detailed analysis of the heat flux method for measuring burning velocity, Combustion and Flame 132 (2003) 170-180] was used for measurement of burning velocities. Initially experiments were done for methane-air and ethane-air mixtures at various equivalence ratios and the results were in good agreement with published data in the literature. Computations were performed using PREMIX code with GRI 3.0 reaction mechanism for all the mixtures. Predicted flame structures were used to the explain the effect of N{sub 2} and CO{sub 2} dilution on burning velocity of methane-air flames. Peak burning velocity for CH{sub 4}/CO{sub 2}-air mixtures occur near to {phi} = 1.0. (author)

  5. Hyperpolarized xenon-129 production and applications

    NASA Astrophysics Data System (ADS)

    Ruset, Iulian C.

    Hyperpolarized 3He and 129Xe were initially developed and used in the nuclear physics community. Lately they are primarily used in Medical Resonance Imaging (MRI). Although first MRI polarized gas images were acquired using 129Xe, the research community has focused mostly on 3He, due to the well-known polarizing methods and higher polarization numbers achieved. The main purpose of this thesis is to present a novel design of a large-scale SEOP polarizer for producing large quantities of highly polarized 129Xe. High Rb-Xe spin-exchange rates through long-lived van de Waals molecules at low total pressure, implemented in a novel counterflow polarizer design, resulted in xenon polarization as high as 50% for 1.2 liters/hour, with a maximum of 64% for 0.3 l/h. We characterized and improved the polarization process by finding the optimum operating parameters of the polarizer. Two new methods to efficiently use high-power diode lasers are described: a new optical arrangement for a better beam shaping of fiber coupled lasers and the first external-cavity spectrum narrowing of a stack of laser diode arrays. A new accumulation technique for the hyperpolarized xenon was developed and full recovery of polarization after a freeze-thaw cycle was demonstrated for the first time. Two approaches for xenon delivery, frozen and gas states, were developed. Hyperpolarized xenon transportation to Brigham and Women's Hospital was successfully accomplished for collaborative research. First MRI images using hyperpolarized xenon acquired at BWH are presented. Final chapter is focused on describing a low field human MRI scanner using hyperpolarized 3He. We built a human scale imager with open access for orientational studies of the lung functionality. Horizontal and vertical human lung images were acquired as a first stage of this project.

  6. Metabolic and toxicological effects of water-soluble xenon compounds are studied

    NASA Technical Reports Server (NTRS)

    Finkel, A. J.; Katz, J. J.; Miller, C. E.

    1968-01-01

    Biological properties of water-soluble xenon compounds are the moderate toxicity of these substances, their rapid decomposition in the body, the speed with which the xenate appeared to be reduced to xenon gas, and the very rapid elimination of this gas from the body.

  7. 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

  8. XENON100 Dark Matter Search: Scintillation Response of Liquid Xenon to Electronic Recoils

    NASA Astrophysics Data System (ADS)

    Lim, Kyungeun Elizabeth

    Dark matter is one of the missing pieces necessary to complete the puzzle of the universe. Numerous astrophysical observations at all scales suggest that 23 % of the universe is made of nonluminous, cold, collisionless, nonbaryonic, yet undiscovered dark matter. Weakly Interacting Massive Particles (WIMPs) are the most well-motivated dark matter candidates and significant efforts have been made to search for WIMPs. The XENON100 dark matter experiment is currently the most sensitive experiment in the global race for the first direct detection of WIMP dark matter. XENON100 is a dual-phase (liquid-gas) time projection chamber containing a total of 161 kg of liquid xenon (LXe) with a 62kg WIMP target mass. It has been built with radiopure materials to achieve an ultra-low electromagnetic background and operated at the Laboratori Nazionali del Gran Sasso in Italy. WIMPs are expected to scatter off xenon nuclei in the target volume. Simultaneous measurement of ionization and scintillation produced by nuclear recoils allows for the detection of WIMPs in XENON100. Data from the XENON100 experiment have resulted in the most stringent limits on the spin-independent elastic WIMP-nucleon scattering cross sections for most of the significant WIMP masses. As the experimental precision increases, a better understanding of the scintillation and ionization response of LXe to low energy (< 10 keV) particles is crucial for the interpretation of data from LXe based WIMP searches. A setup has been built and operated at Columbia University to measure the scintillation response of LXe to both electronic and nuclear recoils down to energies of a few keV, in particular for the XENON100 experiment. In this thesis, I present the research carried out in the context of the XENON100 dark matter search experiment. For the theoretical foundation of the XENON100 experiment, the first two chapters are dedicated to the motivation for and detection medium choice of the XENON100 experiment, respectively. A general review about dark matter focusing on WIMPs and their direct detection with liquid noble gas detectors is presented in Chap. 1. LXe as an attractive WIMP detection medium is explained in Chap. 2. The XENON100 detector design, the detector, and its subsystems are detailed in Chap. 3. The calibration of the detector and the characterized detector response used for the discrimination of a WIMP-like signal against background are explained in Chap. 4. In an effort to understand the background, anomalous electronic recoils were studied extensively and are described in Chap. 5. In order to obtain a better understanding of the electronic recoil background of XENON100, including an estimation of the electronic recoil background contribution, as well as to interpret dark matter results such as annual modulation, measurement of the scintillation yield of low-energy electrons in LXe was performed in 2011, with the dedicated setup mentioned above. The results from this measurement are discussed in Chap. 6. Finally, the results for the latest science data from XENON100 to search for WIMPs, comprising 225 live-days taken over 13 months during 2011 and 2012 are explained in Chap. 7.

  9. Acoustic waves in multifractional gas mixture with the inclusion of different materials and dimensions without Phase Transformations

    NASA Astrophysics Data System (ADS)

    Gubaidullin, D. A.; Teregulova, E. A.

    2014-11-01

    The propagation of acoustic waves in mixtures of gas and particle fractions of different materials and sizes is studied. A mathematical model is presented, the dispersion equation is obtained, dispersion curves are calculated. The influence of the particle size and the parameters of the dispersed phase for multifractional gas mixture with ice particles, aluminum and sand on dissipation and dispersion of sound waves is analyzed. A comparison with experiment is conducted.

  10. The mechanism of small-gas detonation in mechanically activated low-density powder mixtures

    NASA Astrophysics Data System (ADS)

    Rashkovskii, S. A.; Dolgoborodov, A. Yu.

    2015-06-01

    A mechanism of supersonic propagation of the energy-release wave in mechanically activated small-gas explosive powder mixtures is proposed. It is shown that, under certain conditions, this process exhibits all the signs of detonation and should be recognized as a kind of thereof. On the other hand, this kind of detonation is fundamentally different from classical detonation, e.g., in gases. Instead of a shock wave, the powder mixture features propagation of a compression wave, in which the powder exhibits densification due to the mutual displacement of particles rather than contraction of the particle material. A chemical reaction is initiated by the mutual friction of particles in the compression wave.

  11. Suppression of gas detonation by a dust cloud at reduced mixture pressures

    NASA Astrophysics Data System (ADS)

    Pinaev, A. V.; Vasil'ev, A. A.; Pinaev, P. A.

    2015-05-01

    The decay of a detonation wave in a mixture propagating through a dust cloud is experimentally studied for three types of silica sand with particle sizes 250-600, 120-250, and 90-120 , mean volume densities 2.2-3.5 g/l, and initial pressure 0.1-0.01 MPa. A non-monotonic character of reduction of wave velocity in the dust cloud is observed, where a secondary detonation can arise behind the leading front of the wave in the course of its attenuation. This situation is induced by the dual role of sand particles in decelerating the flow and simultaneously generating hot spots that promote reaction excitation. As a result, the mechanism of ignition in the decaying detonation wave becomes different. Critical parameters of the dust cloud providing complete suppression of the detonation wave and the flame propagating behind the latter at a reduced initial pressure of the gas mixture are determined.

  12. Discrete velocity computations with stochastic variance reduction of the Boltzmann equation for gas mixtures

    SciTech Connect

    Clarke, Peter; Varghese, Philip; Goldstein, David

    2014-12-09

    We extend a variance reduced discrete velocity method developed at UT Austin [1, 2] to gas mixtures with large mass ratios and flows with trace species. The mixture is stored as a collection of independent velocity distribution functions, each with a unique grid in velocity space. Different collision types (A-A, A-B, B-B, etc.) are treated independently, and the variance reduction scheme is formulated with different equilibrium functions for each separate collision type. The individual treatment of species enables increased focus on species important to the physics of the flow, even if the important species are present in trace amounts. The method is verified through comparisons to Direct Simulation Monte Carlo computations and the computational workload per time step is investigated for the variance reduced method.

  13. Discrete velocity computations with stochastic variance reduction of the Boltzmann equation for gas mixtures

    NASA Astrophysics Data System (ADS)

    Clarke, Peter; Varghese, Philip; Goldstein, David

    2014-12-01

    We extend a variance reduced discrete velocity method developed at UT Austin [1, 2] to gas mixtures with large mass ratios and flows with trace species. The mixture is stored as a collection of independent velocity distribution functions, each with a unique grid in velocity space. Different collision types (A-A, A-B, B-B, etc.) are treated independently, and the variance reduction scheme is formulated with different equilibrium functions for each separate collision type. The individual treatment of species enables increased focus on species important to the physics of the flow, even if the important species are present in trace amounts. The method is verified through comparisons to Direct Simulation Monte Carlo computations and the computational workload per time step is investigated for the variance reduced method.

  14. Measurement of CH density in a pulsed-dc hydrocarbon-gas- mixture discharge

    SciTech Connect

    Brown, Michael S.; Forlines, Robert A.; Ganguly, Biswa N.

    2005-05-15

    Optical and electrical measurements are performed in methane/diluent mixtures in a 250-ns pulsed-dc discharge using a fast-rise-time pulser. In particular, emission and laser-induced-fluorescence studies of CH produced by direct-electron-impact dissociation reveal the postdissociation kinetics of CH as well as a means of estimating the CH density. In a 20-Torr 10%/20%/70% mixture of argon/methane/nitrogen, the instantaneous CH density is determined to be 2.1x10{sup 13} cm{sup -3} at the end of the steady-state voltage and current condition. Kinetics analysis reveals that neutral chemistry with methane is the largest loss process for the CH fragments. Analysis of N{sub 2}(C-B) rotational temperatures indicates that less than 30% of the input electrical energy is deposited as heat in the gas, with the balance going toward dissociation, excitation of internal molecular states, and ionization.

  15. PIXeY - Liquid Xenon R&D at Yale

    NASA Astrophysics Data System (ADS)

    Edwards, Blair; Bernard, Ethan; Cahn, Sidney; Larsen, Nicole; Lyashenko, Alexey; McKinsey, Daniel; Nikkel, James; Shin, Yunchang; Tennyson, Brian; Wahl, Christopher; Destefano, Nicholas; Gai, Moshe

    2013-04-01

    In recent years xenon has risen as a medium for particle detection, exhibiting a number of desirable qualities that make it well-suited for applications such as medical imaging, imaging of nuclear materials, and fundamental physics research. Xenon is a bright scintillator, with a fast (45 ns) response time, a large charge yield and high electron mobility. The high density (3 g/mL) and high atomic number (Z = 54) of liquid xenon make it ideal for detecting gamma rays with high efficiency over large energy ranges. PIXeY (Particle Identification in Xenon at Yale) is a compact, liquid-xenon-based TPC that operates in either single or two-phase (liquid/gas) mode and detects both charge and light signals produced by particle interactions within the detector. The initial goal of the experiment is to study xenon physics with implications for the operation and design for future large scale experiments (for dark matter or double beta decay), including energy resolution and event discrimination. This presentation will provide an overview of the experiment and discuss the xenon physics studies planned, the results so far and a brief overview of future plans.

  16. Modelling of Detonation in PBX 9502 Using a Stiffened-Gas EOS Mixture Model

    NASA Astrophysics Data System (ADS)

    Kiyanda, Charles B.; Short, Mark

    2007-12-01

    A Stiffened-Gas based equation of state (EOS) model is developed for detonation wave propagation in insensitive high explosives. The current paper specifically concerns PBX 9502. The model consists of a mixture of three components (solid reactant, an intermediate reactant and gaseous product) each having a Stiffened Gas EOS. A two-step chemical kinetic scheme is devised to capture the two distinct reaction timescales of detonating PBX 9502. The motivation behind this study is to highlight several issues with the fitting procedures used in the development of "reactive burn" models, and to understand the requirements for the development of predictive reactive burn models. These include sensitivity of detonation wave propagation properties to small changes in the EOS and chemical rate parameters, the implications of different closure models for the mixture EOS, and the physical implications of the wide fiexibility in fitting EOS and rate parameters. The Stiffened-Gas based EOS model is simple enough for analytical analysis, but has sufficient parameters to reasonably capture the dynamics of detonation propagation in PBX 9502. It thus serves as an ideal model system for this study.

  17. 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

  18. 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).

  19. Xenon and iodine reveal multiple distinct exotic xenon components in Efremovka "nanodiamonds"

    NASA Astrophysics Data System (ADS)

    Gilmour, J. D.; Holland, G.; Verchovsky, A. B.; Fisenko, A. V.; Crowther, S. A.; Turner, G.

    2016-03-01

    We identify new xenon components in a nanodiamond-rich residue from the reduced CV3 chondrite Efremovka. We demonstrate for the first time that these, and the previously identified xenon components Xe-P3 and Xe-P6, are associated with elevated I/Xe ratios. The 129I/127I ratio associated with xenon loss from these presolar compositions during processing on planetesimals in the early solar system was (0.369 ± 0.019) × 10-4, a factor of 3-4 lower than the canonical value. This suggests either incorporation of iodine into carbonaceous grains before the last input of freshly synthesized 129I to the solar system's precursor material, or loss of noble gases during processing of planetesimals around 30 Myr after solar system formation. The xenon/iodine ratios and model closure ages were revealed by laser step pyrolysis analysis of a neutron-irradiated, coarse-grained nanodiamond separate. Three distinct low temperature compositions are identified by characteristic I/Xe ratios and 136Xe/132Xe ratios. There is some evidence of multiple compositions with distinct I/Xe ratios in the higher temperature releases associated with Xe-P6. The presence of iodine alongside Q-Xe and these components in nanodiamonds constrains the pathway by which extreme volatiles entered the solid phase and may facilitate the identification of their carriers. There is no detectable iodine contribution to the presolar Xe-HL component, which is released at intermediate temperatures; this suggests a distinct trapping process. Releases associated with the other components all include significant contributions of 128Xe produced from iodine by neutron capture during reactor irradiation. We propose a revised model relating the origin of Xe-P3 (which exhibits an s-process deficit) through a "Q-process" to the Q component (which makes the dominant contribution to the heavy noble gas budget of primitive material). The Q-process incorporates noble gases and iodine into specific carbonaceous phases with mass dependent fractionation relative to the ambient composition. Q-Xe is dominated by the products of this "Q-process" occurring shortly before or during solar system formation. Carriers that trapped xenon by earlier Q-process events were altered, perhaps by supernova shocks, converting some Q carriers into P3 carriers. Unlike Q carriers, these carriers preserve the isotopic signature of the xenon they trapped through oxidation of samples in the laboratory. P3 carriers thus disproportionately sample xenon that was incorporated before galactic chemical evolution had produced the solar xenon signature by enriching ambient xenon with s-process material.

  20. [Quantitative Analysis of the Hydration Process of Mine Gas Mixture Based on Raman Spectroscopy].

    PubMed

    Zhang, Bao-yong; Yu, Yue; Wu, Qiang; Gao, Xia

    2015-07-01

    The research on micro crystal structure of mine gas hydrate is especially significant for the technology of gas hydrate separation. Using Raman spectroscopy to observe hydration process of 3 kinds of mine gas mixture on line which contains high concentration of carbon dioxide, this experiment obtained the information of the hydrate crystals including large and small cage occupancy. Meanwhile obtained the hydration number indirectly based on the statistical thermodynamic model of van der Waals and Platteeuw. The results show that cage occupancy and hydration number of mine gas hydrates change little during different growth stages. The large cages of hydrate phases are nearly full occupied by carbon dioxide and methane molecules together, with the occupancy ratios between 97.70% and 98.68%. Most of the guest molecules in large cages is carbon dioxide (78.58%-94.09%) and only a few (4.52%-19.12%) is filled with methane, it is because carbon dioxide concentration in the gas sample is higher than methane and there is competition between them. However the small cage occupancy ratios is generally low in the range from 17.93% to 82.41%, and the guest molecules are all methane. With the increase of methane concentration in gas sample, the cage occupancy both large and small which methane occupied has increased, meanwhile the large cage occupancy which methane occupied is lower than small cage. The hydration numbers of mine gas hydrate during different growth stages are between 6.13 and 7.33. Small cage occupancy has increased with the increase of methane concentration, this lead to hydration number decreases. Because of the uneven distribution of hydrate growth, the hydration numbers of 3 kinds of gas samples show irregular change during different growth stages. PMID:26717751

  1. A computer program for calculation of spectral radiative properties of gas mixtures

    NASA Technical Reports Server (NTRS)

    Nealy, J. E.

    1975-01-01

    A computer code is described whereby calculations of radiative properties of gas mixtures may be made. The program is arranged so that distinct radiative processes for each species are computed in individual subroutines. Provision is made for calculating radiative properties in nonequilibrium situations - separate rotational, vibrational, and electronic temperatures may be used. These features should provide a flexibility not currently available in such programs. The basic equations and the program listing in FORTRAN 4 language are presented. Sample calculations are given for high temperature air and carbon dioxide and are compared to calculations made with previously developed programs.

  2. Quenching of Particle-Gas Combustible Mixtures Using Electric Particulate Suspension (EPS) and Dispersion Methods

    NASA Technical Reports Server (NTRS)

    Colver, Gerald M.; Goroshin, Samuel; Lee, John H. S.

    2001-01-01

    A cooperative study is being carried out between Iowa State University and McGill University. The new study concerns wall and particle quenching effects in particle-gas mixtures. The primary objective is to measure and interpret flame quenching distances, flammability limits, and burning velocities in particulate suspensions. A secondary objective is to measure particle slip velocities and particle velocity distribution as these influence flame propagation. Two suspension techniques will be utilized and compared: (1) electric particle suspension/EPS; and (2) flow dispersion. Microgravity tests will permit testing of larger particles and higher and more uniform dust concentrations than is possible in normal gravity.

  3. Method of testing gas insulated systems for the presence of conducting particles utilizing a gas mixture of nitrogen and sulfur hexafluoride

    DOEpatents

    Wootton, Roy E.

    1979-01-01

    A method of testing a gas insulated system for the presence of conducting particles. The method includes inserting a gaseous mixture comprising about 98 volume percent nitrogen and about 2 volume percent sulfur hexafluoride into the gas insulated system at a pressure greater than 60 lb./sq. in. gauge, and then applying a test voltage to the system. If particles are present within the system, the gaseous mixture will break down, providing an indicator of the presence of the particles.

  4. Effects of temperature on the carbonation of flue gas desulphurization gypsum using a CO2/N2 gas mixture.

    PubMed

    Lee, Myung Gyu; Ryu, Kyung Won; Chae, Soo Chun; Jang, Young Nam

    2015-01-01

    The carbonation of flue gas desulphurization (FGD) gypsum using a CO2/N2 gas mixture was investigated to study the feasibility of using the flue gas directly in the gypsum carbonation. The effect of the reaction temperature on the carbonation reaction and the carbonation conversion efficiency of the samples were considered. In this study, the carbonation conversion efficiency was calculated using a new method for decreasing the error range from a sample containing unreacted gypsum. The carbonation reaction at 40°C was nearly twice as fast as the reaction at room temperature. In addition, the carbonation conversion efficiency at 40°C (96%) was nearly the same as that at room temperature. However, the efficiency decreased significantly with temperature, especially above 60°C. It can, therefore, be concluded that the direct use of flue gas in gypsum carbonation is most feasible at 40°C. The temperature of carbonation strongly affected the CaCO3 polymorphs and the morphological characteristics. Calcite with various shapes was the dominant (40-90%) phase at all temperatures. At temperatures below 40°C, spherical-shaped vaterite was pronounced, while needle-flower-shaped aragonite was dominant at temperatures above 80°C. PMID:25409589

  5. Gamma detectors based on high-pressure xenon: their development and application

    NASA Astrophysics Data System (ADS)

    Ulin, Sergey E.; Dmitrenko, Valery V.; Grachev, V. M.; Uteshev, Z. M.; Vlasik, K. F.; Chernysheva, I. V.; Dukhvalov, A. G.; Kotler, F. G.; Pushkin, K. N.

    2004-10-01

    Various modifications of xenon detectors and their parameters in comparison with gamma-detectors of other types are considered. Prospects of xenon detectors' applicatins in gamma-spectroscopy based on experimental results are discussed including detection and control of radioactive and fissile materials displacement, definition of uranium enrichment rate, and measurements of nuclear reactor radioactive gas waste concentration. Possibilities for xenon detector use for environmental control and measurement of cosmic gamma radiation on orbital stations are considered.

  6. Gamma detectors based on high pressure xenon: their development and application

    NASA Astrophysics Data System (ADS)

    Ulin, Sergey E.; Dmitrenko, Valery V.; Grachev, V. M.; Uteshev, Z. M.; Vlasic, K. F.; Chernysheva, I. V.; Duhvalov, A. G.; Kotler, F. G.; Pushkin, K. N.

    2004-01-01

    Various modifications of xenon detectors and their parameters in comparison with gamma-detectors of other types are considered. Prospects of xenon detectors' applications in gamma-spectroscopy based on experimental results are discussed including detection and control of radioactive and fissile materials displacement, definition of uranium enrichment rate, and measurements of nuclear reactor radioactive gas waste concentration. Possibilities for xenon detector use for environmental control and measurement of cosmic gamma radiation on orbital stations are considered.

  7. High pressure and temperature optical flow cell for Near-Infra-Red spectroscopic analysis of gas mixtures

    NASA Astrophysics Data System (ADS)

    Norton, C. G.; Suedmeyer, J.; Oderkerk, B.; Fieback, T. M.

    2014-05-01

    A new optical flow cell with a new optical arrangement adapted for high pressures and temperatures using glass fibres to connect light source, cell, and spectrometer has been developed, as part of a larger project comprising new methods for in situ analysis of bio and hydrogen gas mixtures in high pressure and temperature applications. The analysis is based on measurements of optical, thermo-physical, and electromagnetic properties in gas mixtures with newly developed high pressure property sensors, which are mounted in a new apparatus which can generate gas mixtures with up to six components with an uncertainty of composition of as little as 0.1 mol. %. Measurements of several pure components of natural gases and biogases to a pressure of 20 MPa were performed on two isotherms, and with binary mixtures of the same pure gases at pressures to 17.5 MPa. Thereby a new method of analyzing the obtained spectra based on the partial density of methane was investigated.

  8. Value and limits of Graham's law for prediction of diffusivities of gases in gas mixtures.

    PubMed

    Piiper, J; Worth, H

    1980-09-01

    The validity of Graham's law, i.e. the inversely proportional relationship between diffusivity (diffusion coefficient) and the square root of the molecular mass, is tested for test gases and gas mixtures of physiological interest based on recent measurements of diffusivities of gases in gas phase. With gases of medium molecular mass (10 to 30 g/mol) predictions on the basis of Graham's law are reasonably accurate, deviations from experimental values not exceeding 20%. With gases of high and low molecular masses, however, larger discrepancies are encountered. The prediction of diffusion coefficients on the basis of the Chapman-Enskog theory is in most cases more accurate than that based on Graham's law. PMID:7455395

  9. Calibration method for the quantitative analysis of gas mixtures by means of multiphoton ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Boesl, U.; Weickhardt, C.; Schmidt, S.; Nagel, H.; Schlag, E. W.

    1993-12-01

    A technique for quantitative analysis of gas mixtures in a laser mass spectrometer is presented. It is based on the addition of two calibration gases with different orders of multiphoton ionization process to the sample gas. The ratio of the signals of these two internal standards serves as a sensor for the laser intensity within the ionization volume. Thus strongly fluctuating signals due to higher-order multiphoton ionization can be normalized for every single laser shot. In addition, for such a relative measurement, effects of long-term drifts of the apparatus are eliminated. Concentrations varying from a few ppm to several percent could be determined with an accuracy better than 10% at every single laser shot. Therefore this technique allows high time resolution.

  10. Richtmyer-Meshkov instability in dilute gas-particle mixtures with re-shock

    NASA Astrophysics Data System (ADS)

    Schulz, J. C.; Gottiparthi, K. C.; Menon, S.

    2013-11-01

    The Richtmyer-Meshkov instability (RMI) is investigated in a dilute gas-particle mixture using three-dimensional numerical simulations. This work extends an earlier two-dimensional study [S. Ukai, K. Balakrishnan, and S. Menon, "On Richtmyer-Meshkov instability in dilute gas-particle mixtures," Phys. Fluids 22, 104103 (2010)] to a larger parameter space consisting of variations in the mass loading and the particle size as well as considering both single-mode and multi-mode interface initializations. In addition, the effect of the presence of particles on re-shock RMI is also investigated. Single-phase numerical predictions of the mixing layer growth-rate are shown to compare well to both experimental and theoretical results. In a dilute gas-particle mixture, the initial growth-rate of RMI shows similar trends compared to previous work; however, the current numerical predictions show that there is an observable increase, not previously predicted, in the growth of the mixing layer at higher mass loadings. For the range of cases considered, an increase as much as 56% is observed. This increase is attributed to additional vorticity production in the mixing layer resulting from inter-phase momentum coupling. Moreover, the presence of particles introduces a continuous drag on the gas-phase resulting in a delay in the time at which re-shock occurs. This delay, which is observed to be as much as 6%, is largest for higher initial mass loadings and smaller particle radii and has a corresponding effect on both the growth-rate of the mixing-layer after re-shock and the final width of the mixing layer. A new semi-analytical correlation is developed and verified against the numerical data to predict the re-shocked RMI growth-rate in dilute gas-particle flows. The correlation shows that the re-shock RMI growth-rate is linearly proportional to the velocity jump at re-shock, the molecular mixing fraction, and the multi-phase Atwood number. Depending on the initial mass loading and particle radii, the re-shock RMI growth-rates were observed to be reduced by as much as 48% in some cases with variations of around 26% in the width of the mixing layer after re-shock.

  11. 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).

  12. Transport Properties of He-N{sub 2} Binary Gas Mixtures for CBC Space Applications

    SciTech Connect

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

    2008-01-21

    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 N{sub 2} and the binary mixtures of He-N{sub 2}. 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.

  13. Effect of porosity on flow of miscible fluid mixture by a lattice gas Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Cueva, Luis; Pandey, Ras; Stauffer, Dietrich; Seyfarth, Ray; Gettrust, Joe; Wood, Warren

    2002-03-01

    Using an interacting lattice gas model, flow of a fluid mixture through porous media is studied in three dimensions. The porous medium is generated by a random distribution of barriers (sediments) on a discrete lattice with porosity p above the percolation threshold p_c. The fluid mixture consists of constituents A and B with their mass ratios, 1, 1/2, 1/3, etc. We consider a set of interactions: AB attractive, AA and BB repulsive, A and B with pore attractive, and a hard-core interaction with the sediment barrier. A source of fluid mixture is connected to the bottom where the fluid constituents may enter the porous matrix but they can escape the system from bottom or top. The Metropolis algorithm is used to move fluid particles. While the sedimentation is caused by the gravity, the concentration gradient drives the fluid from bottom to top. The flow rate density is examined as a function of porosity and is found to scale with p-pc with a power-law exponent close to 2.

  14. Gas energy meter for inferential determination of thermophysical properties of a gas mixture at multiple states of the gas

    DOEpatents

    Morrow, Thomas B.; Kelner, Eric; Owen, Thomas E.

    2008-07-08

    A gas energy meter that acquires the data and performs the processing for an inferential determination of one or more gas properties, such as heating value, molecular weight, or density. The meter has a sensor module that acquires temperature, pressure, CO2, and speed of sound data. Data is acquired at two different states of the gas, which eliminates the need to determine the concentration of nitrogen in the gas. A processing module receives this data and uses it to perform a "two-state" inferential algorithm.

  15. 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

    ... 10 Energy 4 2012-01-01 2012-01-01 false Prohibition against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.7 Prohibition against excessive use of petroleum or natural gas... technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an...

  16. 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

    ... 10 Energy 4 2014-01-01 2014-01-01 false Prohibition against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.7 Prohibition against excessive use of petroleum or natural gas... technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an...

  17. 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

    ... 10 Energy 4 2013-01-01 2013-01-01 false Prohibition against excessive use of petroleum or natural...) ALTERNATE FUELS EXISTING POWERPLANTS § 504.7 Prohibition against excessive use of petroleum or natural gas... technically and financially feasible for a unit to use a mixture of petroleum or natural gas and an...

  18. Novel simulated moving-bed adsorber for the fractionation of gas mixtures.

    PubMed

    Rao, D P; Sivakumar, S V; Mandal, Susmita; Kota, Sridevi; Ramaprasad, B S G

    2005-03-25

    The separation of propylene-propane mixture is an energy intensive operation commercially practiced using cryogenic distillation. The separation by pressure swing adsorption has been studied as an alternative. A fixed-bed pressure swing adsorption yields the heavy component as a pure product. The product recovery and the productivity are not high. In a moving-bed process, because of the counter-current solid-gas contact, the separation achieved is similar to that of the fractionation by distillation. Although the moving-bed operation offers the upper limit for the performance of a cyclic adsorptive process, due to mechanical complexities in the handling of solids the 'simulated' moving-bed is preferred. By moving the inlet and outlet ports of streams located along the length of the bed, a moving-bed process can be realized in a fixed bed. We describe here a 'moving-port' system which permits injection or withdrawal of the fluid along the axial direction in a fixed bed. A fixed bed embedded with the moving-port systems emulates a simulated moving-bed adsorber. The proposed adsorber can fractionate a binary gas mixture into two product streams with high purities. It is similar to the Sorbex process of UOP but does not have the eluent as an additional separating agent. A parametric study indicates that high purity products and a higher productivity by an order of magnitude can be achieved with simulated moving-beds compared to the fixed beds. PMID:15844493

  19. Modelling of detonation in PBX 9502 with a stiffened-gas EOS mixture model

    NASA Astrophysics Data System (ADS)

    Kiyanda, Charles; Short, Mark

    2007-06-01

    An analytically tractable model of detonation in PBX 9502 is developed. It consists of a mixture of reactant and product materials, with each component represented by a stiffened-gas equation of state. The five free thermodynamic parameters in the model allow us to address some of the restrictions of simpler analytical models. We first explore generic properties of the steady ZND detonation structure under this model. Secondly, we show that fitting of the thermodynamic data to experimental data on reactant and product properties yields non-intersecting Hugoniot curves. The associated chemical kinetic scheme consists of two reaction steps. The first step has a pressure dependent rate term. It takes the reactants to an intermediate state, a mixture of effectively mostly gaseous products with some solid carbon. The second step models the clustering of solid carbon atoms. Pop-plot and detonation velocity vs. curvature data are used to fit the chemical kinetic parameters. Finally, the linear stability of PBX 9502 detonation waves modeled by the stiffened gas system is studied.

  20. Electron transport and ionization in CHF3 Ar and CHF3 N2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Hernández-Ávila, J. L.; Basurto, E.; de Urquijo, J.

    2004-11-01

    The pulsed Townsend technique has been used to measure the electron drift velocity, the density-normalized effective ionization coefficient (α - η)/N (α and η are the ionization and attachment coefficients, respectively), the density-normalized longitudinal diffusion coefficient NDL, and the ratio between the longitudinal diffusion coefficient and the electron mobility DL/K, in CHF3 mixed with Ar and N2, over a wide range of the density-normalized electric field strength E/N, from 0.2 to 400 Td (1 Td = 10-17 V cm2). The CHF3 content in the mixtures was varied between 1% and 50%. Regions of negative differential conductivity (NDC) appear in the plots of the electron drift velocity as a function of E/N. This effect is more pronounced for the CHF3-Ar mixtures than for the CHF3-N2 ones, since it results from the presence of a Ramsauer-Townsend minimum in the momentum transfer cross section for Ar, which is absent in N2. For the CHF3-N2 case, a shallow region of NDC is observed, and it is thought to be due to various inelastic collision processes between the electrons and the buffer gas, and also to the steep fall of the scattering cross sections for CHF3 at low electron energies. Additionally, the dependence of NDL on E/N displays well-defined minima at low E/N, which are a result of the strong inelastic energy loss of the electrons. The effective ionization coefficients were found to be weakly dependent on the concentration mixture for CHF3-N2, while a strong dependence on this parameter was found for the CHF3-Ar mixture. In all cases, the attaching character of the mixtures was found to be very small. For low E/N (< 20%) in the CHF3-N2 mixture it was observed that the values of (α - η)/N are higher than those expected due to electron impact. We believe that Penning ionization may be responsible for this effect.

  1. Particle size distribution effects in an irradiated turbulent gas-particle mixture

    NASA Astrophysics Data System (ADS)

    Rahmani, Mona; Geraci, Gianluca; Iaccarino, Gianluca; Mani, Ali

    2015-11-01

    The effects of particle size distribution on thermodynamic and hydrodynamic behavior of solid particle solar receivers, that involve a turbulent mixture of gas and particles in a radiation environment, are investigated, using DNS with point particles. The turbulent flow is seeded with monodisperse and polydisperse particles, where the mass loading and total frontal area of particles are matched between the two systems. The results show that the variability of the Stokes number for polydisperse particles can significantly influence the particle clustering, and consequently the thermal performance of the system. In all cases studied, the preferential concentration is less pronounced for polydisperse as opposed to monodisperse particles. This reduced preferential concentration results in less heating of the particles, but more efficient energy release to the gas phase. Due to their different clustering patterns, polydisperse particles influence the Taylor scale of the flow in the turbulent gas phase. Polydispersity also implies variable thermodynamic and hydrodynamic properties of the particles. Our results show that the thermal behavior of the system with polydisperse particles is set by the integral measures for particle and gas momentum and thermal relaxation times.

  2. Study of DC Circuit Breaker of H2-N2 Mixture Gas for High Voltage

    NASA Astrophysics Data System (ADS)

    Shiba, Yuji; Morishita, Yukinaga; Kaneko, Shuhei; Okabe, Shigemitsu; Mizoguchi, Hitoshi; Yanabu, Satoru

    Global warming caused by CO2 etc. is a field where the concern is very high. Especially, automobile emissions are problem for it. Therefore, the hybrid car is widely development and used recently. Hybrid car used electric power and gasoline. So, the car reduces CO2. Hybrid car has engine and motor. To rotate the motor, hybrid car has battery. This battery is large capacity. Therefore, the relay should interrupt high DC current for the switch of the motor and the engine. So, hybrid car used hydrogen gas filling relay We studied interruption test for the research of a basic characteristic of hydrogen gas. DC current has not current zero point. So, it is necessary to make the current zero by high arc voltage and forcible current zero point. The loss coefficient and arc voltage of hydrogen is high. Therefore, we studied interruption test for used high arc voltage. We studied interruption test and dielectric breakdown test of air, pure Hydrogen, and Hydrogen- nitrogen mixture gas. As a result, we realized H2-N2(80%-20%) is the best gas.

  3. The Fate and Environmental Consequences of Reduced gas Mixtures Resulting from Magmatic Intrusion into Carbonaceous Rocks

    NASA Astrophysics Data System (ADS)

    Iacono-Marziano, Giada; Marecal, Virginie; Pirre, Michel; Arndt, Nicolas; Ganino, Clément; Gaillard, Fabrice

    2010-05-01

    Recent developments on the impacts of Large Igneous Provinces on climate changes and extinction rates emphasize the fundamental role of country rocks in gas emissions. Contact metamorphism of country rocks intruded by sills and dikes of mafic melts can be particularly important due to their long exposure to high temperatures. When the host rocks are composed of carbonates, sulphates, salts, or organic-compounds such as bituminous shales or coals, their heating can inject into the atmosphere a quantity of volatiles that greatly exceeds the amount delivered by purely magmatic degassing. We focus here on the interaction between magma and carbonaceous rocks. Recent studies have estimated the gas released by contact metamorphism of bituminous shales in the Karoo Province; we calculate the composition of the volcanic gases which results on this interaction, taking into account the magmatic contribution too. We then present an evaluation of the fate of such gases during their diffusion in the atmosphere. The modelling of the composition of the modified volcanic gases is based on gas-melt thermodynamic calculations that take into account S-H-O-C gaseous species at temperatures and pressures in equilibrium with basaltic liquids. We simulate the incorporation into the gas-melt system of organic compounds as CH or CH2, depending on the maturity of the carbonaceous rocks (coal or oil). Addition of C and H has a dramatic effect on the amount and the redox state of the gas in equilibrium with the basalt. With the incorporation of only 0.2 wt% CH, the gas composition changes from CO2-H2O dominated (typical of basaltic gases on Earth), to CO-H2 dominated (a strongly reduced mixture, which resembles Martian volcanic gases). Addition of more than 0.2 wt% CH can trigger graphite saturation, such as reported in few locations where carbonaceous rocks have been ingested by basalts. In the famous Disko Island location, for example, we calculate that an incorporation of 1 wt% CH led to saturation in metal iron. These "modified" volcanic gases are injected into the atmosphere at a rate directly proportional to the eruption rates and then disseminated. Using a 3D atmospheric algorithm coupling convective dynamics and chemistry, we model the expansion of the gas at a continental scale. Our simulations show that, at reasonable gas emission rates, no significant oxidation of CO occurs because the OH-radical concentration is strongly reduced due to the large concentration of CO and H2. This allows the gas to propagate faraway from the emission centre. The lateral propagation of the gas is significant at the scale of a continent within 2 weeks, which might reveal a new mechanism for mass extinctions.

  4. Study of quantification and distribution of explosive mixture in a confined space as a result of natural gas leak

    NASA Astrophysics Data System (ADS)

    Tulach, Aleš; Mynarz, Miroslav; Kozubková, Milada

    2014-03-01

    The contribution deals with quantification of natural gas leak from a domestic low pressure pipe to a confined space in relation to formation of explosive concentration. Within the experiments, amount of leak gas was determined considering the character of pipe damage. Leakage coefficients, natural gas expansion and time before reaching the lower explosive limit of a gas-air mixture were taken. Conducted experiments were then modelled using CFD software and the results were verified. In numerical model, several models of flow were used and afterwards following issues were analysed: leakage velocity, spatial distribution of the mixture in a confined space, formation of concentration at the lower explosive limit etc. This work should contribute to better understanding of propagation and distribution of gaseous fuel mixtures in confined spaces and thereby significantly reduce the risk of fires or explosions or prevent them.

  5. Cs vapor microcells with Ne-He buffer gas mixture for high operation-temperature miniature atomic clocks.

    PubMed

    Kroemer, E; Abdel Hafiz, M; Maurice, V; Fouilland, B; Gorecki, C; Boudot, R

    2015-07-13

    We report on the characterization of Cs vapor microfabricated cells filled with a Ne-He buffer gas mixture using coherent population trapping (CPT) spectroscopy. The temperature dependence of the Cs clock frequency is found to be canceled at the first order around a so-called inversion temperature higher than 80°C whose value depends on the buffer gas partial pressure ratio. This buffer gas mixture could be well-adapted for the development of miniature atomic clocks devoted to be used in specific applications such as defense and avionic systems with high operating temperature environment (typically higher than 85°C). This solution suggests an alternative to buffer gas mixtures generally used in optically-pumped vapor cell atomic clocks. PMID:26191895

  6. 2D fluid simulations of discharges at atmospheric pressure in reactive gas mixtures

    NASA Astrophysics Data System (ADS)

    Bourdon, Anne

    2015-09-01

    Since a few years, low-temperature atmospheric pressure discharges have received a considerable interest as they efficiently produce many reactive chemical species at a low energy cost. This potential is of great interest for a wide range of applications as plasma assisted combustion or biomedical applications. Then, in current simulations of atmospheric pressure discharges, there is the need to take into account detailed kinetic schemes. It is interesting to note that in some conditions, the kinetics of the discharge may play a role on the discharge dynamics itself. To illustrate this, we consider the case of the propagation of He-N2 discharges in long capillary tubes, studied for the development of medical devices for endoscopic applications. Simulation results put forward that the discharge dynamics and structure depend on the amount of N2 in the He-N2 mixture. In particular, as the amount of N2 admixture increases, the discharge propagation velocity in the tube increases, reaches a maximum for about 0 . 1 % of N2 and then decreases, in agreement with experiments. For applications as plasma assisted combustion with nanosecond repetitively pulsed discharges, there is the need to handle the very different timescales of the nanosecond discharge with the much longer (micro to millisecond) timescales of combustion processes. This is challenging from a computational point of view. It is also important to better understand the coupling of the plasma induced chemistry and the gas heating. To illustrate this, we present the simulation of the flame ignition in lean mixtures by a nanosecond pulsed discharge between two point electrodes. In particular, among the different discharge regimes of nanosecond repetitively pulsed discharges, a ``spark'' regime has been put forward in the experiments, with an ultra-fast local heating of the gas. For other discharge regimes, the gas heating is much weaker. We have simulated the nanosecond spark regime and have observed shock waves generated by the discharge, in agreement with experiments. Then, we have studied the production of active species for the different regimes of nanosecond repetitively pulsed discharges. We present the relative importance of gas heating and the production of active species for the ignition of lean H2-air and CH4-air mixtures. This work has been partially supported by the project ANR DRACO (Grant No. ANR-13-IS09-0004).

  7. Separation Analysis in a High-Speed Rotating Cylinder for a Binary Gas Mixture

    NASA Astrophysics Data System (ADS)

    Pradhan, Sahadev; Kumaran, Viswanathan

    2015-11-01

    The solutions of the species balance equations linked with the generalized Onsager model for the secondary gas flow in a high-speed rotating cylinder are compared with the direct simulation Monte Carlo (DSMC) simulations for a binary gas mixture. The concentration fields are obtained three different types of driving mechanism. These are: (a) wall thermal forcing, (b) inflow/outflow of gas along the axis, and (c) momentum source/sink inside the flow domain, for the stratification parameter (A) in the range (0.707- 3.535), and Reynolds number (Re) in the range (102 - 106 with aspect ratio (length / diameter) = 2, 4, 8. Two different types of cases have been considered, (a) no mass difference (ɛa = (2 Δm/(m1 + m2)) = 0), and (b) with mass difference (ɛa = 0.2 and 0.5) while calculating the secondary flow field in the analytical solution. Here, the stratification prameter A = √((mavΩ2 R2)/(2 kB T)), and the Reynolds number Re = ρw Ω R2)/ μ, where m is the molecular mass, Ω and R are the angular velocity and radius of the cylinder, ρw is the wall density, μ is the gas viscosity and T is the gas temperature. The comparison between numerical and analytical solution reveals that the boundary conditions in the numerical simulations and analytical model have to be matched with care. The commonly used ``diffuse reflection'' boundary conditions at the solid walls in DSMC simulations result in a non-zero slip velocity as well as a ``temperature slip'' (gas temperature at the wall is different from wall temperature).

  8. Xenon-Ion Drilling of Tungsten Films

    NASA Technical Reports Server (NTRS)

    Garner, C. E.

    1986-01-01

    High-velocity xenon ions used to drill holes of controlled size and distribution through tungsten layer that sheaths surface of controlled-porosity dispenser cathode of traveling wave-tube electron emitter. Controlled-porosity dispenser cathode employs barium/calcium/ aluminum oxide mixture that migrates through pores in cathode surface, thus coating it and reducing its work function. Rapid, precise drilling technique applied to films of other metals and used in other applications where micron-scale holes required. Method requires only few hours, as opposed to tens of hours by prior methods.

  9. Theoretical study of thermal conductivities of various gas mixtures through the generalized Lennard-Jones interaction potential for application in gas-discharge lasers

    NASA Astrophysics Data System (ADS)

    Temelkov, K. A.; Slaveeva, S. I.; Fedchenko, Yu I.

    2016-03-01

    Thermal conductivities of helium, neon, bromine, and hydrogen are calculated on the basis of the (12-6) Lennard-Jones interaction approximation. Where necessary for a more precise approximation, a generalized (n-m) Lennard-Jones interaction potential is used. Thermal conductivities of binary gas systems are calculated and compared through two different empirical methods for the case of gas discharges in He, Ne, and Ne-He mixtures with small admixtures of bromine and hydrogen. A new simple method is proposed for the thermal conductivity determination for the 3- and 4-component gas mixtures of our interest.

  10. Minimum Error Fickian Diffusion Coefficients for Mass Diffusion in Multicomponent Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Subramaniam, S.

    1999-04-01

    Mass diffusion in multicomponent gas mixtures is governed by a coupled system of linear equations for the diffusive mass fluxes in terms of thermodynamic driving forces, known as the generalized Stefan-Maxwell equation. In computations of mass diffusion in multicomponent gas mixtures, this coupling between the different components results in considerable computational overhead. Consequently, simplified diffusion models for the diffusive mass fluxes as explicit functions of the driving forces are an attractive alternative. These models can be interpreted as an approximate solution to the Stefan-Maxwell equation. Simplified diffusion models require the specification of “effective” diffusion coefficients which are usually expressed as functions of the binary diffusion coefficients of each species pair in the mixture. Current models for the effective diffusion coefficients are incapable of providing a priori control over the error incurred in the approximate solution. In this paper a general form for diagonal approximations is derived, which accounts for the requirement imposed by the special structure of the Stefan-Maxwell equation that such approximations be constructed in a reduced-dimensional subspace. In addition, it is shown that current models can be expressed as particular cases of two general forms, but not all these models correspond to the general form for diagonal approximations. A new minimum error diagonal approximation (MEDA) model is proposed, based on the criterion that the diagonal approximation minimize the error in the species velocities. Analytic expressions are derived for the MEDA model's effective diffusion coefficients based on this criterion. These effective diffusion coefficients automatically give the correct solution in two important limiting cases: for that of a binary mixture, and for the case of arbitrary number of components with identical binary diffusivities. Although these minimum error effective diffusion coefficients are more expensive to compute than existing ones, the approximation will still be cheaper than computing the exact Stefan-Maxwell solution, while at the same time being more accurate than any other diagonal approximation. Furthermore, while the minimum error effective diffusion coefficients in this work are derived for bulk diffusion in homogeneous media, the minimization procedure can in principle be used to derive similar coefficients for diffusion problems in heterogeneous media which can be represented by similar forms of the Stefan-Maxwell equation. These problems include diffusion in macro- and microporous catalysts, adsorbents, and membranes.

  11. Biofiltration of mixtures of gas-phase styrene and acetone with the fungus Sporothrix variecibatus.

    PubMed

    Rene, Eldon R; Spačková, Radka; Veiga, María C; Kennes, Christian

    2010-12-15

    The biodegradation performance of a biofilter, inoculated with the fungus Sporothrix variecibatus, to treat gas-phase styrene and acetone mixtures under steady-state and transient conditions was evaluated. Experiments were carried out by varying the gas-flow rates (0.05-0.4m(3)h(-1)), leading to empty bed residence times as low as 17.1s, and by changing the concentrations of gas-phase styrene (0.01-6.3 g m(-3)) and acetone (0.01-8.9 g m(-3)). The total elimination capacities were as high as 360 g m(-3)h(-1), with nearly 97.5% removal of styrene and 75.6% for acetone. The biodegradation of acetone was inhibited by the presence of styrene, while styrene removal was affected only slightly by the presence of acetone. During transient-state experiments, increasing the overall pollutant load by almost 3-fold, i.e., from 220 to 600 g m(-3)h(-1), resulted in a sudden drop of removal efficiency (>90-70%), but still high elimination capacities were maintained. Periodic microscopic observations revealed that the originally inoculated Sporothrix sp. remained present in the reactor and actively dominant in the biofilm. PMID:20869172

  12. 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.

  13. XENON-133 IN CALIFORNIA, NEVADA, AND UTAH FROM THE CHERNOBYL ACCIDENT (JOURNAL VERSION)

    EPA Science Inventory

    The accident at the Chernobyl nuclear reactor in the USSR introduced numerous radioactive nuclides into the atmosphere, including the noble gas xenon-133. EPA's Environmental Monitoring Systems Laboratory, Las Vegas, NV, detected xenon-133 from the Chernobyl accident in air sampl...

  14. 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.

  15. Monitoring of the dielectric strength of the air/SF6-mixtures for application in gas insulated transmission lines

    NASA Astrophysics Data System (ADS)

    Moukengué Imano, A.

    2004-11-01

    This paper investigates the dielectric properties of various air/SF{6} gas mixtures based upon a cylindrical spacer model with adhering particle on the surface under homogeneous field conditions. The investigation involves a comparison with pure SF{6}. The flashover field strength for clean and particle contaminated spacer surface under lightning impulse (LI) and alternating voltage (AC) stress is determined. The results of the investigations show the sensitivity of air/SF{6} gas mixtures to conducting particles on spacer surfaces for gas pressure up to 1000 kPa. Moreover, the correspondence between pure SF{6} and air/SF{6} gas mixtures for AC and LI flashover field strength range from 50 to 178 kV/cm is determined. Conclusions are drawn about the ability of air/SF{6} gas mixtures to serve as technically efficient media for long Gas Insulated Transmission Lines (GITL). The results shed light on the issue of the SF{6} reduction and the particle detectability in GITL.

  16. 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.

    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.

  17. Xenon Suboxides Stable under Pressure.

    PubMed

    Hermann, Andreas; Schwerdtfeger, Peter

    2014-12-18

    We present results from first-principles calculations on solid xenon-oxygen compounds under pressure. We find that the xenon suboxide Xe3O2 is the first compound to become more stable than the elements, at around P = 75 GPa. Other, even more xenon-rich compounds follow at higher pressures, while no region of enthalpic stability is found for the monoxide XeO. We establish the spectroscopic fingerprints of a variety of structural candidates for a recently synthesized xenon-oxygen compound at atmospheric pressure and, on the basis of the proposed stoichiometry XeO2, suggest an orthorhombic structure that comprises extended sheets of square-planar-coordinated xenon atoms connected through bent Xe-O-Xe linkages. PMID:26273984

  18. Intense vacuum ultraviolet and infrared scintillation of liquid Ar-Xe mixtures

    NASA Astrophysics Data System (ADS)

    Neumeier, A.; Dandl, T.; Heindl, T.; Himpsl, A.; Oberauer, L.; Potzel, W.; Roth, S.; Schönert, S.; Wieser, J.; Ulrich, A.

    2015-01-01

    Vacuum ultraviolet light emission from xenon-doped liquid argon is described in the context of liquid noble gas particle detectors. Xenon concentrations in liquid argon from 0.1 ppm to 1000 ppm were studied. The energy transfer from the second excimer continuum of argon (˜127 \\text{nm}) to the second excimer continuum of xenon (˜174 \\text{nm}) is observed by recording optical emission spectra. The transfer almost saturates at a xenon concentration of ˜10 \\text{ppm} for which, in addition, an intense emission in the infrared at a peak wavelength of 1.17 μ \\text{m} with 13000 +/- 4000 photons per MeV deposited by electrons had been found. The corresponding value for the VUV emission at a peak wavelength of 174 nm (second excimer continuum of xenon) is determined to be 20000 +/- 6000 photons per MeV electron energy deposited. Under these excitation conditions pure liquid argon emits 22000 +/- 3000 photons per MeV electron energy deposited at a peak wavelength of 127 nm. An electron-beam-induced emission spectrum for the 10 ppm Ar-Xe liquid mixture ranging from 115 nm to 3.5 μ \\text{m} is presented. VUV emission spectra from xenon-doped liquid argon with exponentially varied xenon concentrations from 0.1 ppm to 1000 ppm are also shown. Time structure measurements of the light emissions at well-defined wavelength positions in the vacuum ultraviolet as well as in the near-infrared are presented.

  19. Multiproperty empirical isotropic interatomic potentials for CH4–inert gas mixtures

    PubMed Central

    El-Kader, M.S.A.

    2012-01-01

    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

  20. Evidence for double incoherent Raman scattering in binary gas mixtures: SF6-N2

    NASA Astrophysics Data System (ADS)

    Verzhbitskiy, I. A.; Chrysos, M.; Rachet, F.; Kouzov, A. P.

    2010-01-01

    We report a collision-induced Raman band by room temperature gas mixtures of sulfur hexafluoride and nitrogen. The band is centered at the sum of the frequencies of the symmetric-stretching ν1 transition of SF6 and the fundamental transition of N2, and its intensity scales as the product of the partial densities of the gases. The observed process is evidence of double incoherent Raman scattering (DRS) by SF6-N2, in which both molecules simultaneously undergo two Raman-allowed transitions. The band was found to be almost fully depolarized, in agreement with previous observations in other systems and with theoretical predictions. Its integrated intensity is about one-third higher than the total area predicted by the leading-order dipole-induced dipole model. This discrepancy suggests that DRS is a practical means of assessing the quality of intermolecular potential models, which, in the case of SF6-N2, is still believed to be not good enough. Our work is expected to open the door to a multitude of studies involving complicated processes encountered in nonpolar gases and their mixtures, which are of direct relevance to atmospheric research.

  1. Ultra-cold dilute gas Bose-Fermi mixture with ^87Rb and ^40K

    NASA Astrophysics Data System (ADS)

    Goldwin, J.; Olsen, M. L.; Inouye, S.; Jin, D. S.

    2003-05-01

    Sympathetic cooling experiments with Bose-Fermi mixtures offer a way to cool Fermi gases to quantum degeneracy with relatively little loss in atom number, as well as offering interesting new systems for study with the control and precision typical of atomic physics experiments. Here we report on the sympathetic cooling of fermionic ^40K with bosonic ^87Rb. We first trap and cool ^87Rb atoms in a two-species MOT together with ^40K. After loading into a purely magnetic quadrupole configuration trap, the gas is transferred mechanically nearly a meter to a Ioffe-Pritchard type magnetic trap in an ultra-high vacuum cell. radio-frequency induced evaporation of the ^87Rb atoms results in pure Bose-Einstein condensates of 2 10^5 atoms. In the process ^40K atoms are cooled by virtue of thermal contact with the ^87Rb reservoir resulting in cooling of ^40K, with 1 10^4 atoms at temperatures below 100 nK. We present results from the experiment demonstrating the efficiency of the cooling, and describe ongoing investigations into the limits of the cooling and the strong inter-species interactions in the mixture. Finally, future directions for the experiment are discussed.

  2. Development of proton-conducting membranes for separating hydrogen from gas mixtures

    SciTech Connect

    Dorris, S.E.; Balachandran

    1996-06-01

    Dense ceramic membranes made from mixed protonic/electronic conductors are permeable only to hydrogen, and in principle, provide a simple efficient means of separating hydrogen from gas mixtures. At a time when world demand for hydrogen is growing, such proton- conducting membranes have the potential to significantly alter the economics of hydrogen separation and purification processes and thus improve the economic viability of processes that utilize hydrogen, such as some refinery operations and direct and indirect coal liquefaction. This paper describes a recently initiated program to develop materials and fabrication processes to separate hydrogen with dense ceramic membranes in a non-Galvanic mode of operation (i.e., without electrodes or external power supply).

  3. The equivalent electrical permittivity of gas-solid mixtures at intermediate solid volume fractions.

    SciTech Connect

    Torczynski, John Robert; Ceccio, Steven Louis; Tortora, Paul Richard

    2005-07-01

    Several mixture models are evaluated for their suitability in predicting the equivalent permittivity of dielectric particles in a dielectric medium for intermediate solid volume fractions (0.4 to 0.6). Predictions of the Maxwell, Rayleigh, Bottcher and Bruggeman models are compared to computational simulations of several arrangements of solid particles in a gas and to the experimentally determined permittivity of a static particle bed. The experiment uses spherical glass beads in air, so air and glass permittivity values (1 and 7, respectively) are used with all of the models and simulations. The experimental system used to measure the permittivity of the static particle bed and its calibration are described. The Rayleigh model is found to be suitable for predicting permittivity over the entire range of solid volume fractions (0-0.6).

  4. Methodology for Predicting Flammable Gas Mixtures in Double Contained Receiver Tanks [SEC 1 THRU SEC 3

    SciTech Connect

    HEDENGREN, D.C.

    2000-01-31

    This methodology document provides an estimate of the maximum concentrations of flammable gases (ammonia, hydrogen, and methane) which could exist in the vapor space of a double-contained receiver tank (DCRT) from the simultaneous saltwell pumping of one or more single-shell tanks (SSTs). This document expands Calculation Note 118 (Hedengren et a1 1997) and removes some of the conservatism from it, especially in vapor phase ammonia predictions. The methodologies of Calculation Note 118 (Hedengren et a1 1997) are essentially identical for predicting flammable gas mixtures in DCRTs from saltwell pumping for low DCRT ventilation rates, 1e, < 1 cfm. The hydrogen generation model has also been updated in the methodology of this document.

  5. Collision kernels for the Waldmann-Snider equation: generalization to gas mixtures

    NASA Astrophysics Data System (ADS)

    Demeio, Lucio; Monchick, Louis

    1995-02-01

    In this paper we generalize the collision kernel method, which had only been worked out for the test particle limit of the linearized Waldmann-Snider equations, to the general linearized Waldmann-Snider equations for non-equilibrium gas mixtures of finite concentration. By using the total angular momentum representation for the transition matrix and a suitable coordinate transformation, which takes advantage of the rotational symmetries of the kernel, the ten-dimensional collision integrals are reduced to sets of two-dimensional integrals. The transformation by Hilbert of the classical Boltzmann equation for rigid spheres to a Fredholm integral equation with symmetric kernel has thus been extended to the Waldmann-Snider equation for diatomic molecules. This transformation enables the extension of collocation methods, which have been profitably used with model Boltzmann equations, to quantum Boltzmann equations that describe the kinetic theory of gases with real molecules.

  6. Investigation of electrooptical breakdown threshold in gas mixtures of complex chemical composition

    NASA Astrophysics Data System (ADS)

    Y Loktionov, E.; Pasechnikov, N. A.; Pavlov, A. V.; Protasov, Y. S.; Telekh, V. D.

    2015-11-01

    The results of combined electrooptical breakdown (DC E∼0-13.2 kV/cm + laser λ-213, 266, 355, 532, 1064 nm, τ0,5∼18 ns, I0∼109-1011 W/cm2) of gases (He, Ne, Ar, Kr) and their binary and triple mixtures at subatmospheric pressure (101-105 Pa) experimental investigation are presented for the first time. Thresholds of optical, electrical and combined electrooptical breakdown for those were experimentally determined. The possibility of breakdown threshold components decrease at simultaneous optical and electrical impact on the gas, and the possibility of lowering the thresholds of the combined breakdown of doped gases have been investigated.

  7. Asymptotic modelling of the flow of a thermal binary gas mixture in a microchannel

    NASA Astrophysics Data System (ADS)

    Gatignol, R.; Croizet, C.

    2014-12-01

    The paper purpose is to investigate asymptotic models to describe the basic physical phenomena of flows of a thermal binary gas mixture in coplanar microchannels. The steady flows of gases are described by the Navier-Stokes-Fourier equations, with first order slip boundary conditions for the velocities and jump boundary conditions for the temperatures on the microchannel walls. Taking into account the small parameter equal to the ratio of the two longitudinal and transversal lengths, an asymptotic model is proposed, corresponding to low Mach numbers and to low or moderate Knudsen numbers. Several aspects of the solutions are discussed. We pay attention to the influence of the temperature gradient which is present along the walls. In particular, it is shown that a change in the temperature gradient can induce a change in the longitudinal flow direction. Finally, a result of DSMC similation and the corresponding asymptotic solution are compared.

  8. Relaxation combustion of gas mixture in a tube: Paradox piston motion

    NASA Astrophysics Data System (ADS)

    Alekseev, M. M.; Samsonov, V. P.; Semenov, O. Yu.

    2013-05-01

    The pattern of the propagation of the propane-air flame front and a piston from a closed tube end to an open end that is investigated experimentally. It is shown that the tube length and the coefficient of the tube being filled up by a combustible mixture are determining conditions for generation of oscillations of the piston and the flame front. It is found that the velocities of the piston and the flame front are directed oppositely to each other in definite phases of oscillations. Gas oscillations in the tube trigger a relaxation combustion mode at which the velocity of the flame front effects a variation in the amplitude-frequency characteristics. The time dependences of a periodic variation in coordinates of the piston and the flame front are represented. A physical explanation of the phenomenon of mutual approaching of the flame front and the piston is proposed.

  9. Synthesis of formamide and isocyanic acid after ion irradiation of frozen gas mixtures

    NASA Astrophysics Data System (ADS)

    Kaňuchová, Z.; Urso, R. G.; Baratta, G. A.; Brucato, J. R.; Palumbo, M. E.; Strazzulla, G.

    2016-01-01

    Context. Formamide (NH2HCO) and isocyanic acid (HNCO) have been observed as gaseous species in several astronomical environments such as cometary comae and pre- and proto-stellar objects. A debate is open on the formation route of those molecules, in particular if they are formed by chemical reactions in the gas phase and/or on grains. In this latter case it is relevant to understand if the formation occurs through surface reactions or is induced by energetic processing. Aims: We present arguments that support the formation of formamide in the solid phase by cosmic-ion-induced energetic processing of ices present as mantles of interstellar grains and on comets. Formamides, along with other molecules, are expelled in the gas phase when the physical parameters are appropriate to induce the desorption of ices. Methods: We have performed several laboratory experiments in which ice mixtures (H2O:CH4:N2, H2O:CH4:NH3, and CH3OH:N2) were bombarded with energetic (30-200 keV) ions (H+ or He+). FTIR spectroscopy was performed before, during, and after ion bombardment. In particular, the formation of HNCO and NH2HCO was measured quantiatively. Results: Energetic processing of ice can quantitatively reproduce the amount of NH2HCO observed in cometary comae and in many circumstellar regions. HNCO is also formed, but additional formation mechanisms are requested to quantitatively account for the astronomical observations. Conclusions: We suggest that energetic processing of ices in the pre- and proto-stellar regions and in comets is the main mechanism to produce formamide, which, once it is released in the gas phase because of desorption of ices, is observed in the gas phase in these astrophysical environments.

  10. 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.

  11. 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

  12. Supersonic Flow of Chemically Reacting Gas-Particle Mixtures. Volume 2: RAMP - A Computer Code for Analysis of Chemically Reacting Gas-Particle Flows

    NASA Technical Reports Server (NTRS)

    Penny, M. M.; Smith, S. D.; Anderson, P. G.; Sulyma, P. R.; Pearson, M. L.

    1976-01-01

    A computer program written in conjunction with the numerical solution of the flow of chemically reacting gas-particle mixtures was documented. The solution to the set of governing equations was obtained by utilizing the method of characteristics. The equations cast in characteristic form were shown to be formally the same for ideal, frozen, chemical equilibrium and chemical non-equilibrium reacting gas mixtures. The characteristic directions for the gas-particle system are found to be the conventional gas Mach lines, the gas streamlines and the particle streamlines. The basic mesh construction for the flow solution is along streamlines and normals to the streamlines for axisymmetric or two-dimensional flow. The analysis gives detailed information of the supersonic flow and provides for a continuous solution of the nozzle and exhaust plume flow fields. Boundary conditions for the flow solution are either the nozzle wall or the exhaust plume boundary.

  13. Xenon-enhanced CT imaging of local pulmonary ventilation

    NASA Astrophysics Data System (ADS)

    Tajik, Jehangir K.; Tran, Binh Q.; Hoffman, Eric A.

    1996-04-01

    We are using the unique features of electron beam CT (EBCT) in conjunction with respiratory and cardiac gating to explore the use of non-radioactive xenon gas as a pulmonary ventilation contrast agent. The goal is to construct accurate and quantitative high-resolution maps of local pulmonary ventilation in humans. We are evaluating xenon-enhanced computed tomography in the pig model with dynamic tracer washout/dilution and single breath inhalation imaging protocols. Scanning is done via an EBCT scanner which offers 50 msec scan aperture speeds. CT attenuation coefficients (image gray scale value) show a linear increase with xenon concentration (r equals 0.99). We measure a 1.55 Hounsfield Unit (HU) enhancement (kV equals 130, mA equals 623) per percentage increase in xenon gas concentration giving an approximately 155 HU enhancement with 100% xenon gas concentration as measured in a plexiglass super-syringe. Early results indicate that a single breath (from functional residual capacity to total lung capacity) of 100% xenon gas provides an average 32 +/- 1.85 (SE) HU enhancement in the lung parenchyma (maximum 50 HU) and should not encounter unwanted xenon side effects. However, changes in lung density occurring during even short breath holds (as short as 10 seconds) may limit using a single breath technique to synchronous volumetric scanning, currently possible only with EBCT. Preliminary results indicate close agreement between measured regional xenon concentration-time curves and theoretical predictions for the same sample. More than 10 breaths with inspirations to as high as 25 cmH2O airway pressure were needed to clear tracer from all lung regions and some regions had nearly linear rather than mono-exponential clearance curves. When regional parenchymal xenon concentration-time curves were analyzed, vertical gradients in ventilation and redistribution of ventilation at higher inspiratory flow rates were consistent with known pulmonary physiology. We present here a works in progress, showing results from two pigs illustrating the high resolution and detailed regional information obtainable with careful attention to cardiac and respiratory gating during a multi-breath washout period.

  14. Xenon Tetrafluoride: Reaction with Aqueous Solutions.

    PubMed

    Williamson, S M; Koch, C W

    1963-03-15

    Xenon tetrafluoride reacts with water to yield xenon, oxygen, hydrofluoric acid, and a very soluble species containing xenon. Evaporation of the solution yields a white, crystal-line substance which has been identified as xenon (VI) oxide, XeO(3). PMID:17812981

  15. Hydrogen generation in a microhollow cathode discharge in high-pressure ammonia-argon gas mixtures

    NASA Astrophysics Data System (ADS)

    Qiu, H.; Martus, K.; Lee, W. Y.; Becker, K.

    2004-04-01

    We explored the feasibility of using a single flow-through microhollow cathode discharge (MHCD) as a non-thermal plasma source for hydrogen (H2) production for portable fuel cell applications. The MHCD device consisted of two thin metal electrodes separated by a mica spacer with a single-hole, roughly 100 [mu]m in diameter, through all three layers. The efficiency of the MHCD reactor for H2 generation from NH3 was analyzed by monitoring the products formed in the discharge in a mass spectrometer. Using a gas mixture of up to 10% NH3 in Ar at pressures up to one atmosphere, the MHCD reactor achieved a maximum ammonia conversion of slightly more than 20%. The overall power efficiency of the MHCD reactor reached a peak value of about 11%. The dependence of NH3 conversion and power efficiency on the residence time of the gas in the MHCD plasma was studied. Experiments using pulsed excitation of the MHCD plasma indicated that pulsing can increase the power efficiency. Design and operating criteria are proposed for a microplasma-based H2 generator that can achieve a power efficiency above the break-even point, i.e., a microplasma reactor that requires less electrical power to generate and maintain the plasma than the power that can be obtained from the conversion of the H2 generated in the microplasma reactor.

  16. 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.

  17. Gas mixtures for quality control of the sTGC chambers

    NASA Astrophysics Data System (ADS)

    Filippov, K. A.; Konovalov, S. P.; Mikenberg, G.; Romaniouk, A.; Shchukin, D.; Shoa, M.; Smakhtin, V.; Smirnov, S. Yu; Sosnovtsev, V. V.; Teterin, P. E.; Tikhomirov, V. O.; Tsekhosh, V. I.; Vorobev, K. A.

    2016-02-01

    sTGC chambers are designed to operate at super-LHC conditions and will be installed in place during Phase-I upgrade of the ATLAS muon spectrometer. These chambers will provide precise coordinate measurements of the charged particle tracks and level 1 trigger for high pT muons. It is critical for the ATLAS detector to ensure a robust operation of these chambers during entire sLHC period. A quality control procedure based on X-ray scanner is being developed. Choice of the active gas for these tests is a very important issue. On one hand it should allow to find different types of chamber production defects, on the other hand one has to be sure that found problems are essential for the detector operation in future. Studies of the operation of the sTGC chamber prototype under X-ray irradiation with two gas mixtures (n- pentane/CO2 and CO2) were performed. The prototype was irradiated by X-rays with energy up to 50 keV. Particular attention was paid to the study of the “hot” chamber regions.

  18. Electron bunching in a Penning trap and accelerating process for CO2 gas mixture active medium

    NASA Astrophysics Data System (ADS)

    Tian, Xiu-Fang; Wu, Cong-Feng; Jia, Qi-Ka

    2015-12-01

    In PASER (particle acceleration by stimulated emission of radiation), in the presence of an active medium incorporated in a Penning trap, moving electrons can become bunched, and as they get enough energy, they escape the trap forming an optical injector. These bunched electrons can enter the next PASER section filled with the same active medium to be accelerated. In this paper, electron dynamics in the presence of a gas mixture active medium incorporated in a Penning trap is analyzed by developing an idealized 1D model. We evaluate the energy exchange occurring as the train of electrons traverses into the next PASER section. The results show that the oscillating electrons can be bunched at the resonant frequency of the active medium. The influence of the trapped time and population inversion are analyzed, showing that the longer the electrons are trapped, the more energy from the medium the accelerated electrons get, and with the increase of population inversion, the decelerated electrons are virtually unchanged but the accelerated electrons more than double their peak energy values. The simulation results show that the gas active medium needs a lower population inversion to bunch the electrons compared to a solid active medium, so the experimental conditions can easily be achieved. Supported by National Natural Science Foundation of China (10675116) and Major State Basic Research Development Programme of China (2011CB808301)

  19. Density functional theory of gas-liquid phase separation in dilute binary mixtures.

    PubMed

    Okamoto, Ryuichi; Onuki, Akira

    2016-06-22

    We examine statics and dynamics of phase-separated states of dilute binary mixtures using density functional theory. In our systems, the difference of the solvation chemical potential between liquid and gas [Formula: see text] (the Gibbs energy of transfer) is considerably larger than the thermal energy [Formula: see text] for each solute particle and the attractive interaction among the solute particles is weaker than that among the solvent particles. In these conditions, the saturated vapor pressure increases by [Formula: see text], where [Formula: see text] is the solute density added in liquid. For [Formula: see text], phase separation is induced at low solute densities in liquid and the new phase remains in gaseous states, even when the liquid pressure is outside the coexistence curve of the solvent. This explains the widely observed formation of stable nanobubbles in ambient water with a dissolved gas. We calculate the density and stress profiles across planar and spherical interfaces, where the surface tension decreases with increasing interfacial solute adsorption. We realize stable solute-rich bubbles with radius about 30 nm, which minimize the free energy functional. We then study dynamics around such a bubble after a decompression of the surrounding liquid, where the bubble undergoes a damped oscillation. In addition, we present some exact and approximate expressions for the surface tension and the interfacial stress tensor. PMID:27115676

  20. 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.

  1. Xenon improves neurological outcome and reduces secondary injury following trauma in an in vivo model of traumatic brain injury

    PubMed Central

    Luh, Clara; Gruss, Marco; Radyushkin, Konstantin; Hirnet, Tobias; Werner, Christian; Engelhard, Kristin; Franks, Nicholas P; Thal, Serge C; Dickinson, Robert

    2015-01-01

    Objectives To determine the neuroprotective efficacy of the inert gas xenon following traumatic brain injury, and to determine whether application of xenon has a clinically relevant therapeutic time window. Design Controlled animal study. Setting University research laboratory. Subjects Male C57BL/6N mice (n=196) Interventions 75% xenon, 50% xenon or 30% xenon, with 25% oxygen (balance nitrogen) treatment following mechanical brain lesion by controlled cortical impact. Measurements & Main Results Outcome following trauma was measured using: 1) functional neurological outcome score, 2) histological measurement of contusion volume, 3) analysis of locomotor function and gait. Our study shows that xenon-treatment improves outcome following traumatic brain injury. Neurological outcome scores were significantly (p<0.05) better in xenon-treated groups in the early phase (24 hours) and up to 4 days after injury. Contusion volume was significantly (p<0.05) reduced in the xenon-treated groups. Xenon treatment significantly (p<0.05) reduced contusion volume when xenon was given 15 minutes after injury or when treatment was delayed 1 hour or 3 hours after injury. Neurological outcome was significantly (p<0.05) improved when xenon treatment was given 15 minutes or 1 hour after injury. Improvements in locomotor function (p<0.05) were observed in the xenon-treated group, 1 month after trauma. Conclusions These results show for the first time that xenon improves neurological outcome and reduces contusion volume following traumatic brain injury in mice. In this model, xenon application has a therapeutic time window of up to at least 3 hours. These findings support the idea that xenon may be of benefit as a neuroprotective treatment in brain trauma patients. PMID:25188549

  2. 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.

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

    PubMed

    Dong, Ki-Young; Choi, Jinnil; Lee, Yang Doo; Kang, Byung Hyun; Yu, Youn-Yeol; Choi, Hyang Hee; Ju, Byeong-Kwon

    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

  4. The krypton and xenon markets up to the year 2000

    NASA Astrophysics Data System (ADS)

    Hammarlund, Nils

    1992-05-01

    Krypton and xenon are rare gases which are found in air in concentrations of about 1.14 and 0.087 ppm, respectively. They are produced in specially equipped, very large air separation units by adding a special raw gas extraction unit. Then this raw gas is purified and the krypton and xenon are separated by cryogenic methods. These rare gases are used in the lamp industry, for medical applications and in laser and research applications. The market for krypton and xenon is growing. The production capacity for these gases is limited and this results in a cyclic behavior of availability and market price. In the next few years, 10-20 million liters of krypton and one to two million liters of xenon will become available on the market due to new investments in the USA, South Africa and the AGA AB joint venture in the USSR. The total world production capacity of krypton and xenon will increase to 60-80 million liters. To influence the availability of these gases it is important to have close partnership between user and producer, which will realize bright and unorthodox ideas for the supply and use of these rare gases.

  5. 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

  6. 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.

  7. 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 μm for CO(2)/H(2) and 0.26 ± 0.04 μm 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

  8. Evaluation of error sources in a gravimetric technique for preparation of a reference gas mixture (carbon dioxide in synthetic air).

    PubMed

    Matsumoto, Nobuhiro; Shimosaka, Takuya; Watanabe, Takuro; Kato, Kenji

    2008-07-01

    One method of preparing a primary reference gas mixture is the gravimetric blending method. Uncertainty of a few mg in mass measurements is unavoidable when preparing reference gas mixtures under current laboratory conditions with our facilities, equipment, and materials. There are many sources of errors when using this method. In this study, several sources of errors were re-evaluated for our process for preparation of carbon dioxide in synthetic air. As a consequence of the re-evaluation, it was found that some sources of errors had significant effects on gravimetric concentrations of the gas mixtures. These sources are: (1) different masses of the reference cylinder and sample cylinder (an error in the readings of the electronic mass comparator), (2) leakage of the inner gas from valves of the cylinders, and (3) cooling of the gas cylinder caused by filling with high-pressure liquefied carbon dioxide gas. When the mass measurements were performed under uncontrolled conditions, the errors due to sources (1), (2), and (3) were as high as 20 mg, 24 mg, and 13 mg, respectively. In this paper, the detailed results from re-evaluation of these sources of errors are discussed. PMID:18454348

  9. Effect of Alumina on the Gaseous Reduction of Magnetite in CO/CO2 Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Kapelyushin, Yury; Xing, Xing; Zhang, Jianqiang; Jeong, Sunkwang; Sasaki, Yasushi; Ostrovski, Oleg

    2015-03-01

    Reduction of magnetite doped with alumina (3, 6 and 12 mass pct Al2O3) was studied using CO/CO2 gas mixture (80 vol pct CO) at 1023 K and 1123 K (750 °C and 850 °C). The reduction rate and degree of reduction were evaluated from the weight loss of a sample with time. The reduction behavior was analyzed using the results of XRD and SEM-EDS measurements and thermodynamic analysis. Effect of alumina on the magnetite reduction depended on the alumina content and temperature. Magnetite reduction at 1023 K (750 °C) was accelerated by the addition of 3 mass pct Al2O3, however, the rate of reduction significantly decreased with the further increase in the alumina content to 6 and 12 mass pct. Different effect of alumina was observed in reduction at 1123 K (850 °C); the rate of reduction of the Fe3O4-Al2O3 mixture with 6 mass pct Al2O3 was the fastest. Reduction of un-doped magnetite was developed topochemically with the formation of a dense iron shell. However, reduction of alumina-doped magnetite to wüstite started along certain lattice planes with the formation of network-like structure. In the course of reduction, Al3+ ions diffused from wüstite to the Fe3O4-FeAl2O4 solution enriching hercynite content in the solution at the reaction interface. Further reduction of alumina-rich Fe3O4-FeAl2O4 solution resulted in the formation of micro-cracks which enhanced the rate of the reduction process.

  10. Simulation of the transition radiation detection conditions in the ATLAS TRT detector filled with argon and krypton gas mixtures

    SciTech Connect

    Boldyrev, A. S.; Maevskiy, A. S.

    2015-12-15

    Performance of the Transition Radiation Tracker (TRT) at the ATLAS experiment with argon and krypton gas mixtures was simulated. The efficiency of transition radiation registration, which is necessary for electron identification, was estimated along with the electron identification capabilities under such conditions.

  11. Simulation of the transition radiation detection conditions in the ATLAS TRT detector filled with argon and krypton gas mixtures

    NASA Astrophysics Data System (ADS)

    Boldyrev, A. S.; Maevskiy, A. S.

    2015-12-01

    Performance of the Transition Radiation Tracker (TRT) at the ATLAS experiment with argon and krypton gas mixtures was simulated. The efficiency of transition radiation registration, which is necessary for electron identification, was estimated along with the electron identification capabilities under such conditions.

  12. Two-phase mixture in a reactor with a TPJ gas distributor: The statistical model of bubble population

    SciTech Connect

    Pindur, K.; Pawelczyk, R.

    1996-12-31

    Statistical description is presented of the population of bubbles produced in a two-phase mixture in a reactor using a novel TPJ (Two Perpendicular Jets) gas distributor. The analysis performed supports the idea that it is the lognormal distribution which should be assumed as a statistical model of the population of bubble diameters.

  13. Introducing Students to Gas Chromatography-Mass Spectrometry Analysis and Determination of Kerosene Components in a Complex Mixture

    ERIC Educational Resources Information Center

    Pacot, Giselle Mae M.; Lee, Lyn May; Chin, Sung-Tong; Marriott, Philip J.

    2016-01-01

    Gas chromatography-mass spectrometry (GC-MS) and GC-tandem MS (GC-MS/MS) are useful in many separation and characterization procedures. GC-MS is now a common tool in industry and research, and increasingly, GC-MS/MS is applied to the measurement of trace components in complex mixtures. This report describes an upper-level undergraduate experiment…

  14. Chondritic xenon in the Earth's mantle.

    PubMed

    Caracausi, Antonio; Avice, Guillaume; Burnard, Peter G; Füri, Evelyn; Marty, Bernard

    2016-05-01

    Noble gas isotopes are powerful tracers of the origins of planetary volatiles, and the accretion and evolution of the Earth. The compositions of magmatic gases provide insights into the evolution of the Earth's mantle and atmosphere. Despite recent analytical progress in the study of planetary materials and mantle-derived gases, the possible dual origin of the planetary gases in the mantle and the atmosphere remains unconstrained. Evidence relating to the relationship between the volatiles within our planet and the potential cosmochemical end-members is scarce. Here we show, using high-precision analysis of magmatic gas from the Eifel volcanic area (in Germany), that the light xenon isotopes identify a chondritic primordial component that differs from the precursor of atmospheric xenon. This is consistent with an asteroidal origin for the volatiles in the Earth's mantle, and indicates that the volatiles in the atmosphere and mantle originated from distinct cosmochemical sources. Furthermore, our data are consistent with the origin of Eifel magmatism being a deep mantle plume. The corresponding mantle source has been isolated from the convective mantle since about 4.45 billion years ago, in agreement with models that predict the early isolation of mantle domains. Xenon isotope systematics support a clear distinction between mid-ocean-ridge and continental or oceanic plume sources, with chemical heterogeneities dating back to the Earth's accretion. The deep reservoir now sampled by the Eifel gas had a lower volatile/refractory (iodine/plutonium) composition than the shallower mantle sampled by mid-ocean-ridge volcanism, highlighting the increasing contribution of volatile-rich material during the first tens of millions of years of terrestrial accretion. PMID:27111512

  15. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures

    NASA Astrophysics Data System (ADS)

    Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel

    2015-04-01

    This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations.

  16. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.

    PubMed

    Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel

    2015-04-01

    This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations. PMID:25854230

  17. General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures

    SciTech Connect

    Liu, Yen Vinokur, Marcel; Panesi, Marco; Sahai, Amal

    2015-04-07

    This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model’s accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy relaxation model, which can only be applied to molecules, the new model is applicable to atoms, molecules, ions, and their mixtures. Numerical examples and model validations are carried out with two gas mixtures using the maximum entropy linear model: one mixture consists of nitrogen molecules undergoing internal excitation and dissociation and the other consists of nitrogen atoms undergoing internal excitation and ionization. Results show that the original hundreds to thousands of microscopic equations can be reduced to two macroscopic equations with almost perfect agreement for the total number density and total internal energy using only one or two groups. We also obtain good prediction of the microscopic state populations using 5-10 groups in the macroscopic equations.

  18. The effects of gas mixtures on ion engine erosion and performance

    NASA Technical Reports Server (NTRS)

    Garner, Charles E.; Brophy, John R.; Aston, Graeme

    1987-01-01

    Erosion measurements were performed on a modified J-series 30 cm ion engine operating on xenon propellant. Erosion data was obtained by measuring the trench depth etched into masked polished metal samples for test durations of up to 24 hours. The data indicates that erosion is greatest at the cathode side of the baffle, with tantalum being the material with the least erosion of all materials tested. There is a clear indication of a significant reduction in erosion of all materials tested when nitrogen is added to the propellant. The technique used in these experiments requires test samples which are extremely smooth and flat.

  19. Supersonic flow of chemically reacting gas-particle mixtures. Volume 1: A theoretical analysis and development of the numerical solution

    NASA Technical Reports Server (NTRS)

    Penny, M. M.; Smith, S. D.; Anderson, P. G.; Sulyma, P. R.; Pearson, M. L.

    1976-01-01

    A numerical solution for chemically reacting supersonic gas-particle flows in rocket nozzles and exhaust plumes was described. The gas-particle flow solution is fully coupled in that the effects of particle drag and heat transfer between the gas and particle phases are treated. Gas and particles exchange momentum via the drag exerted on the gas by the particles. Energy is exchanged between the phases via heat transfer (convection and/or radiation). Thermochemistry calculations (chemical equilibrium, frozen or chemical kinetics) were shown to be uncoupled from the flow solution and, as such, can be solved separately. The solution to the set of governing equations is obtained by utilizing the method of characteristics. The equations cast in characteristic form are shown to be formally the same for ideal, frozen, chemical equilibrium and chemical non-equilibrium reacting gas mixtures. The particle distribution is represented in the numerical solution by a finite distribution of particle sizes.

  20. 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.

  1. Xenon Tetrafluoride: Heat of Formation.

    PubMed

    Gunn, S R; Williamson, S M

    1963-04-12

    Calorimetric measurements of the heat of reaction of xenon tetrafluoride with aqueous iodide solution give -60 kilocalories per mole for the standard heat of formation, or an average thermochemical bond energy of about 31 kilocalories. PMID:17819835

  2. High-power gas-discharge excimer ArF, KrCl, KrF and XeCl lasers utilising two-component gas mixtures without a buffer gas

    NASA Astrophysics Data System (ADS)

    Razhev, A. M.; Kargapol'tsev, E. S.; Churkin, D. S.

    2016-03-01

    Results of an experimental study of the influence of a gas mixture (laser active medium) composition on an output energy and total efficiency of gas-discharge excimer lasers on ArF* (193 nm), KrCl* (222 nm), KrF* (248 nm) and XeCl* (308 nm) molecules operating without a buffer gas are presented. The optimal ratios of gas components (from the viewpoint of a maximum output energy) of an active medium are found, which provide an efficient operation of laser sources. It is experimentally confirmed that for gas-discharge excimer lasers on halogenides of inert gases the presence of a buffer gas in an active medium is not a necessary condition for efficient operation. For the first time, in two-component gas mixtures of repetitively pulsed gas-discharge excimer lasers on electron transitions of excimer molecules ArF*, KrCl*, KrF* and XeCl*, the pulsed energy of laser radiation obtained under pumping by a transverse volume electric discharge in a low-pressure gas mixture without a buffer gas reached up to 170 mJ and a high pulsed output power (of up to 24 MW) was obtained at a FWHM duration of the KrF-laser pulse of 7 ns. The maximal total efficiency obtained in the experiment with two-component gas mixtures of KrF and XeCl lasers was 0.8%.

  3. Scaling laws for the atomic Xe laser in Ne/Ar/Xe and He/Ar/Xe gas mixtures

    SciTech Connect

    Vogel, M.S.; Jong, W.; Kushner, S.

    1992-12-01

    The atomic Xe laser oscillates on 6 transitions (1.73 {mu}m - 3.7 {mu}m) between the 5d and 6p manifolds. Ar/Xe gas mixtures usually produce the highest laser efficiencies at 1.73 {mu}m, however gas heating from energy loading can reduce or terminate laser output due to an increase in the electron density. One is therefore motivated to increase the gas pressure by adding a lighter rare gas (He or Ne). The scaling of the atomic Xe laser using Ne/Ar/Xe and He/Ar/Xe gas mixtures have been investigated using a computer model. Addition of Ne significantly alters the kinetic pathways leading to increased pumping of the 6p manifold by dissociative recombination of Xe{sub 2}{sup +} thereby decreasing laser power. Increasing the heat capacity of the mixture by adding Ne can regain some of this loss at high energy loading. He addition is less disruptive with respect to the ion chemistry, but preferential quenching of the lower laser levels causes osciallation to be dominantly at 2.03 {mu}m.

  4. 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.

  5. Irradiated Xenon Isotopic Ratio Measurement for Failed Fuel Detection and Location in Fast Reactor

    NASA Astrophysics Data System (ADS)

    Ito, Chikara; Iguchi, Tetsuo; Harano, Hideki

    2009-08-01

    The accuracy of xenon isotopic ratio burn-up calculations used for failed fuel identification was evaluated by an irradiation test of xenon tag gas samples in the Joyo test reactor. The experiment was carried out using pressurized steel capsules containing unique blend ratios of stable xenon tag gases in an on-line creep rupture experiment in Joyo. The tag gas samples were irradiated to total neutron fluences of 1.6 to 4.8 × 1026 n/m2. Laser resonance ionization mass spectrometry was used to analyze the cover gas containing released tag gas diluted to isotopic ratios of 100 to 102 ppb. The isotopic ratios of xenon tag gases after irradiation were calculated using the ORIGEN2 code. The neutron cross sections of xenon nuclides were based on the JENDL-3.3 library. These cross sections were collapsed into one group using the neutron spectra of Joyo. The comparison of measured and calculated xenon isotopic ratios provided C/E values that ranged from 0.92 to 1.10. The differences between calculation and measurement were considered to be mainly due to the measurement errors and the xenon nuclide cross section uncertainties.

  6. Theoretical and experimental studies of sodium-xenon absorption spectra and applications to lighting

    NASA Astrophysics Data System (ADS)

    Babb, J. F.; Chung, H.-K.; Shurgalin, M.; Yoshino, K.; Kirby, K.; Parkinson, W.

    2000-01-01

    Theory and experiment are being used together to explore spectra from sodium and xenon gas mixtures similar to those used in high pressure lamps. Results from high precision measurements of the absorption coefficients over the wavelength range from 425 to 760 nm are presented with 0.02 nm spectral resolution. Measurements of the sodium density with plus or minus five percent uncertainty complement the absorption coefficient measurements. The experimental data are compared to quantum-mechanical spectral calculations that utilize recent cold collision and other data. The spectra are sensitive to the interatomic potentials, especially in the far wings in which molecular features such as vibrational-rotational and satellite structures are exhibited. The particular results for Na-Xe are analyzed in detail.

  7. Theoretical and experimental studies of sodium-xenon absorption spectra and applications to lighting

    NASA Astrophysics Data System (ADS)

    Babb, J. F.; Chung, H.-K.; Shurgalin, M.; Yoshino, K.; Kirby, K.; Parkinson, W.

    2000-11-01

    Theory and experiment are being used together to explore spectra from sodium and xenon gas mixtures similar to those used in high pressure lamps. Results from high precision measurements of the absorption coefficients over the wavelength range from 425 to 760 nm are presented with 0.02 nm spectral resolution. Measurements of the sodium density with ±5 percent uncertainty complement the absorption coefficient measurements. The experimental data are compared to quantum-mechanical spectral calculations that utilize recent cold collision and other data. The spectra are sensitive to the interatomic potentials, especially in the far wings in which molecular features such as vibrational-rotational and satellite structures are exhibited. The particular results for Na-Xe are analyzed in detail.

  8. Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 January--31 March 1995

    SciTech Connect

    Iglesia, E.

    1995-04-24

    The contract objectives are: to design a catalytic material for the synthesis of isobutanol with a productivity of 200 g isoalcohols/g-cat-h and a molar isobutanol/methanol ratio near unity; and to develop structure-function rules for the design of catalysts for the selective conversion of synthesis gas to isoalcohols. Several catalyst samples have been prepared by controlled co-precipitation from aqueous mixtures of metal nitrates. The composition of these materials is based on reports of best available catalysts for methanol synthesis, for isobutanol synthesis, and for methanol coupling reactions. The mechanical construction and pressure testing of the microreactor system has been completed. The in-situ infrared spectrophotometer equipped with a nitrogen purge is fully operational. The temperature-programmed surface reaction (TPSR) unit has been designed; construction will begin during the third quarter FY`95. Air Products and Chemicals has provided us with a sample of a BASF isobutanol synthesis catalyst and with catalytic data obtained on this catalyst in a LaPorte test run. This catalyst will serve as a benchmark for the certification of our new microreactor system.

  9. Analysis of siloxanes in hydrocarbon mixtures using comprehensive two-dimensional gas chromatography.

    PubMed

    Ghosh, Abhijit; Seeley, Stacy K; Nartker, Steven R; Seeley, John V

    2014-09-19

    A comprehensive two-dimensional gas chromatography (GC×GC) method for separating siloxanes from hydrocarbons has been developed using a systematic process. First, the retention indices of a set of siloxanes and a set of hydrocarbons were determined on 6 different stationary phases. The retention indices were then used to model GC×GC separation on 15 different stationary phase pairs. The SPB-Octyl×DB-1 pair was predicted to provide the best separation of the siloxanes from the hydrocarbons. The efficacy of this stationary phase pair was experimentally tested by performing a GC×GC analysis of gasoline spiked with siloxanes and by analyzing biogas obtained from a local wastewater treatment facility. The model predictions agreed well with the experimental results. The SPB-Octyl×DB-1 stationary phase pair constrained the hydrocarbons to a narrow range of secondary retention times and fully isolated the siloxanes from the hydrocarbon band. The resulting GC×GC method allows siloxanes to be resolved from complex mixtures of hydrocarbons without requiring the use of a selective detector. PMID:25087744

  10. Effect of focal size on the laser ignition of compressed natural gas-air mixture

    NASA Astrophysics Data System (ADS)

    Srivastava, Dhananjay Kumar; Wintner, Ernst; Agarwal, Avinash Kumar

    2014-07-01

    Laser ignition of compressed natural gas-air mixtures was investigated in a constant volume combustion chamber (CVCC) as well as in a single cylinder engine. Laser ignition has several potential advantages over conventional spark ignition system. Laser ignition relies on the fact that optical breakdown (plasma generation) in gases occurs at high intensities of ≈1011 W/cm2. Such high intensities can be achieved by focusing a pulsed laser beam to small focal sizes. The focal spot size depends on several parameters such as laser wavelength, beam diameter at the converging lens, beam quality and focal length. In this investigation, the focal length of the converging lens and the beam quality were varied and the corresponding effects on minimum ignition energy as well as pressure rise were recorded. The flame kernel was visualized and correlated with the rate of pressure rise inside the combustion chamber. This investigation will be helpful in the optimization of laser and optics parameters in laser ignition. It was found that beam quality factor and focal length of focusing lens have a strong impact on the minimum ignition energy required for combustion. Combustion duration depends on the energy density at the focal spot and size of the flame kernel.

  11. Flow rate measurements of binary gas mixtures through long trapezoidal microchannels

    NASA Astrophysics Data System (ADS)

    Szalmas, Lajos; Colin, Stéphane; Valougeorgis, Dimitris

    2012-05-01

    The flow rate of two noble gas mixtures, namely He/Ar and He/Kr, is measured through a microsystem containing 400 long trapezoidal microchannels placed in parallel configuration. Each microchannel has a trapezoidal cross section with long base 5.38 micrometers and height 1.90 micrometers, while its length is 5000 micrometers. The experiment is based on the constant volume method. The flow is driven by pressure gradient. The flow rate measurements refer to downstream pressures of 15.1 kPa and 8.05 kPa. The pressure ratio is in the range of 3-7 and 4-7 for the larger and smaller downstream pressures, respectively. The investigated rarefaction range is in the slip and early transition regions. The concentration of He varies from zero to one. The measured flow rates are compared to the corresponding computational ones obtained by the numerical solution of the McCormack kinetic model. Very good agreement between the experimental and computational results is reached. The difference between the corresponding results is less than the experimental uncertainty. Typical pressure and concentration profiles along the axis and the velocity profiles in the center of the channel obtained from the numerical solution are also presented.

  12. Spectral Characteristics of Deuterium-, Helium- and Gas-Mixture-Discharges within PF-1000 Facility

    NASA Astrophysics Data System (ADS)

    Tsarenko, A.; Malinowski, K.; Sadowski, M. J.; Skladnik-Sadowska, E.; Scholz, M.; Paduch, M.; Tomaszewski, K.

    2006-01-01

    The paper reports on spectroscopic studies of high-current plasma discharges performed at different gas fillings within the large PF-1000 facility. To study visible radiation (VR) the use was made of a MECHELLE®900-spectrometer equipped with the CCD readout. The observations of a PF pinch column were performed at an angle of about 65° to the z-axis, and the viewing field was at a distance of 40-50 mm from the electrode ends. Optical measurements were carried out at 0.5-μs exposition synchronized with a chosen period of the investigated discharge. Differences in the optical spectra, recorded at various deuterium-helium mixtures, were analyzed. Intensities of HeI lines were computed for an assumed electron temperature and compared with the experiment. Estimated plasma concentration in pure-deuterium discharges amounted to 8×1018 cm-3, while that in pure helium shots was (4-7)×1017 cm-3 only. Estimates of the electron temperature, from the ratio of intensities of the chosen spectral lines and the continuum, gave values ranging from 5 eV to 50 eV. The paper presents also some spectra from "weak shots", which show distinct impurity lines caused by different reasons.

  13. High pressure and temperature optical flow cell for near-infra-red spectroscopic analysis of gas mixtures.

    PubMed

    Norton, C G; Suedmeyer, J; Oderkerk, B; Fieback, T M

    2014-05-01

    A new optical flow cell with a new optical arrangement adapted for high pressures and temperatures using glass fibres to connect light source, cell, and spectrometer has been developed, as part of a larger project comprising new methods for in situ analysis of bio and hydrogen gas mixtures in high pressure and temperature applications. The analysis is based on measurements of optical, thermo-physical, and electromagnetic properties in gas mixtures with newly developed high pressure property sensors, which are mounted in a new apparatus which can generate gas mixtures with up to six components with an uncertainty of composition of as little as 0.1 mol. %. Measurements of several pure components of natural gases and biogases to a pressure of 20 MPa were performed on two isotherms, and with binary mixtures of the same pure gases at pressures to 17.5 MPa. Thereby a new method of analyzing the obtained spectra based on the partial density of methane was investigated. PMID:24880347

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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.

  15. Single Ion Trapping for the Enriched Xenon Observatory

    SciTech Connect

    Waldman, Samuel J.; ,

    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.

  16. High-pressure xenon detector development at Constellation Technology Corporation

    NASA Astrophysics Data System (ADS)

    Austin, Robert A.; Bastian, Lloyd F.

    2006-08-01

    Xenon-filled ionization detectors, due to their high atomic number fill gas (Z=54), moderate densities (~0.3 g/cm 3-0.5 g/cm 3) and good energy resolution (2%-4% at 662 keV), fill an important niche between more familiar technologies such as NaI(Tl) scintillators and Germanium detectors. Until recently, difficulties with obtaining sufficient Xenon purity, reducing microphonic sensitivity, and developing low-noise electronics compatible with small ionization signals have hampered the development of this nuclear detection field. Constellation Technology Corporation, whose experience with xenon detectors goes back to the mid 1990's, has made significant progress in these areas and has developed a commercial line of detectors with active volumes ranging from small (35 g Xe) to large (1400 g Xe). Here we will discuss our development of a mobile, large area, spectroscopic array.

  17. 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.

  18. Observation and applications of single-electron charge signals in the XENON100 experiment

    NASA Astrophysics Data System (ADS)

    Aprile, E.; Alfonsi, M.; Arisaka, K.; Arneodo, F.; Balan, C.; Baudis, L.; Bauermeister, B.; Behrens, A.; Beltrame, P.; Bokeloh, K.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Cardoso, J. M. R.; Chen, W.-T.; Choi, B.; Colijn, A. P.; Contreras, H.; Cussonneau, J. P.; Decowski, M. P.; Duchovni, E.; Fattori, S.; Ferella, A. D.; Fulgione, W.; Gao, F.; Garbini, M.; Ghag, C.; Giboni, K.-L.; Goetzke, L. W.; Grignon, C.; Gross, E.; Hampel, W.; Itay, R.; Kaether, F.; Kessler, G.; Kish, A.; Lamblin, J.; Landsman, H.; Lang, R. F.; Le Calloch, M.; Levy, C.; Lim, K. E.; Lin, Q.; Lindemann, S.; Lindner, M.; Lopes, J. A. M.; Lung, K.; Marrodán Undagoitia, T.; Massoli, F. V.; Melgarejo Fernandez, A. J.; Meng, Y.; Messina, M.; Molinario, A.; Naganoma, J.; Ni, K.; Oberlack, U.; Orrigo, S. E. A.; Pantic, E.; Persiani, R.; Piastra, F.; Plante, G.; Priel, N.; Rizzo, A.; Rosendahl, S.; dos Santos, J. M. F.; Sartorelli, G.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Simgen, H.; Teymourian, A.; Thers, D.; Vitells, O.; Wang, H.; Weber, M.; Weinheimer, C.

    2014-03-01

    The XENON100 dark matter experiment uses liquid xenon in a time projection chamber (TPC) to measure xenon nuclear recoils resulting from the scattering of dark matter weakly interacting massive particles (WIMPs). In this paper, we report the observation of single-electron charge signals which are not related to WIMP interactions. These signals, which show the excellent sensitivity of the detector to small charge signals, are explained as being due to the photoionization of impurities in the liquid xenon and of the metal components inside the TPC. They are used as a unique calibration source to characterize the detector. We explain how we can infer crucial parameters for the XENON100 experiment: the secondary-scintillation gain, the extraction yield from the liquid to the gas phase and the electron drift velocity.

  19. Effect of preionization, fluorine concentration, and current density on the discharge uniformity in F2 excimer laser gas mixtures

    NASA Astrophysics Data System (ADS)

    Mathew, D.; Bastiaens, H. M. J.; Boller, K. J.; Peters, P. J. M.

    2007-08-01

    The discharge homogeneity in F2-based excimer laser gas mixtures and its dependence on various key parameters, such as the degree of preionization, preionization delay time, F2 concentration and current density, is investigated in a small x-ray preionized discharge chamber. The spatial and temporal evolution of the discharges is monitored by taking photographs of the discharge fluorescence with a fast intensified CCD camera. It is found that a preionization electron density of about 107 cm-3 bar-1 is sufficient to initiate a streamer-free homogeneous discharge in gas mixtures of helium and fluorine with multiatmospheric gas pressure. The accompanying optimum time delay between the application of the x-ray pulse and voltage across the discharge electrodes is determined to be about 20 ns. It is shown that in spite of these optimum initial conditions, a homogeneous glow discharge eventually transforms into an inhomogeneous discharge containing numerous filaments. Our experiments show that the higher the initial F2 concentration, the initial current density or the pump power density, the shorter the time interval over which the discharge stays homogeneous. By a quantitative characterization and defining a detailed measure of the observed discharge inhomogeneity we find that halogen depletion, as suggested from the theory, is responsible for the temporal instability of discharges in such laser gas mixtures, as the experimental results are in good agreement with the theory on the halogen depletion instability mechanism.

  20. 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.

    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.

  1. Recovery of methane from gas hydrates intercalated within natural sediments using CO(2) and a CO(2)/N(2) gas mixture.

    PubMed

    Koh, Dong-Yeun; Kang, Hyery; Kim, Dae-Ok; Park, Juwoon; Cha, Minjun; Lee, Huen

    2012-08-01

    The direct recovery of methane from massive methane hydrates (MHs), artificial MH-bearing clays, and natural MH-bearing sediments is demonstrated, using either CO(2) or a CO(2)/N(2) gas mixture (20 mol % of CO(2) and 80 mol % of N(2), reproducing flue gas from a power plant) for methane replacement in complex marine systems. Natural gas hydrates (NGHs) can be converted into CO(2) hydrate by a swapping mechanism. The overall process serves a dual purpose: it is a means of sustainable energy-source exploitation and greenhouse-gas sequestration. In particular, scant attention has been paid to the natural sediment clay portion in deep-sea gas hydrates, which is capable of storing a tremendous amount of NGH. The clay interlayer provides a unique chemical-physical environment for gas hydrates. Herein, for the first time, we pull out methane from intercalated methane hydrates in a clay interlayer using CO(2) and a CO(2)/N(2) gas mixture. The results of this study are expected to provide an essential physicochemical background required for large-scale NGH production under the seabed. PMID:22730158

  2. Development of a functionalized Xenon biosensor

    SciTech Connect

    Spence, Megan M.; Ruiz, E. Janette; Rubin, Seth M.; Lowery, Thomas J.; Winssinger, Nicolas; Schultz, Peter G.; Wemmer, David E.; Pines, Alexander

    2004-03-25

    NMR-based biosensors that utilize laser-polarized xenon offer potential advantages beyond current sensing technologies. These advantages include the capacity to simultaneously detect multiple analytes, the applicability to in vivo spectroscopy and imaging, and the possibility of remote amplified detection. Here we present a detailed NMR characterization of the binding of a biotin-derivatized caged-xenon sensor to avidin. Binding of functionalized xenon to avidin leads to a change in the chemical shift of the encapsulated xenon in addition to a broadening of the resonance, both of which serve as NMR markers of ligand-target interaction. A control experiment in which the biotin-binding site of avidin was blocked with native biotin showed no such spectral changes, confirming that only specific binding, rather than nonspecific contact, between avidin and functionalized xenon leads to the effects on the xenon NMR spectrum. The exchange rate of xenon (between solution and cage) and the xenon spin-lattice relaxation rate were not changed significantly upon binding. We describe two methods for enhancing the signal from functionalized xenon by exploiting the laser-polarized xenon magnetization reservoir. We also show that the xenon chemical shifts are distinct for xenon encapsulated in different diastereomeric cage molecules. This demonstrates the potential for tuning the encapsulated xenon chemical shift, which is a key requirement for being able to multiplex the biosensor.

  3. COOMET.QM-S5 (COOMET project No 576/RU/12) 'Supplementary comparison of national standards in the field of analysis of gas mixtures containing CO2, CO, C3H8 in nitrogen ("automotive" gas mixtures)'

    NASA Astrophysics Data System (ADS)

    Konopelko, L. A.; Kolobova, A. V.; Rozhnov, M. S.; Melnyk, D. M.; Petryshyn, P. V.; Shpilnyi, S. A.; Iakubov, S. E.; Bakovec, N. V.; Kluchits, A. S.; Kipphardt, H.; Aleksandrov, V. V.

    2016-01-01

    The relevance of the COOMET.QM-S5 comparison is founded on tightening of requirements to a control of automobile emissions (realization of environmental standards of EURO 4, EURO-5). Participating laboratories: VNIIM, BAM, BelGIM, Ukrmetrteststandart, KazInMetr. This comparison was carried out in 2013-2014. This supplementary comparison supports CMC claims for: CO2 in the range (4-16) . 10-2 mol/mol; CO in the range (0.5-5) . 10-2 mol/mol; C3H8 in the range (0.01-0.3) . 10-2 mol/mol. Results: Component CO: All laboratories identified the values of carbon monoxide mole fraction in the gas mixture within +/-0.9134%. Component CO2: All laboratories identified the values of carbon dioxide mole fraction in the gas mixture within +/-0.3042%. Component C3H8: All laboratories identified the values of propane mole fraction in the gas mixture within +/-0.443%. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  4. Early treatment with xenon protects against the cold ischemia associated with chronic allograft nephropathy in rats.

    PubMed

    Zhao, Hailin; Luo, Xianghong; Zhou, Zhaowei; Liu, Juying; Tralau-Stewart, Catherine; George, Andrew J T; Ma, Daqing

    2014-01-01

    Chronic allograft nephropathy (CAN) is a common finding in kidney grafts with functional impairment. Prolonged hypothermic storage-induced ischemia-reperfusion injury is associated with the early onset of CAN. As the noble gas xenon is clinically used as an anesthetic and has renoprotective properties in a rodent model of ischemia-reperfusion injury, we studied whether early treatment with xenon could attenuate CAN associated with prolonged hypothermic storage. Exposure to xenon enhanced the expression of insulin growth factor-1 (IGF-1) and its receptor in human proximal tubular (HK-2) cells, which, in turn, increased cell proliferation. Xenon treatment before or after hypothermia-hypoxia decreased cell apoptosis and cell inflammation after reoxygenation. The xenon-induced HK-2 cell proliferation was abolished by blocking the IGF-1 receptor, mTOR, and HIF-1? individually. In the Fischer-to-Lewis rat allogeneic renal transplantation model, xenon exposure of donors before graft retrieval or recipients after engraftment enhanced tubular cell proliferation and decreased tubular cell death and cell inflammation associated with ischemia-reperfusion injury. Compared with control allografts, xenon treatment significantly suppressed T-cell infiltration and fibrosis, prevented the development of CAN, and improved renal function. Thus, xenon treatment promoted recovery from ischemia-reperfusion injury and reduced susceptibility to the subsequent development of CAN in allografts. PMID:24025645

  5. Pre-acclimatization to high altitude using exercise with normobaric hypoxic gas mixtures.

    PubMed

    Benoit, H; Germain, M; Barthélémy, J C; Denis, C; Castells, J; Dormois, D; Lacour, J R; Geyssant, A

    1992-10-01

    Pre-acclimatization was conducted using a new method elaborated in our laboratory, combining high intensity exercise while breathing hypoxia normobaric gas mixtures. The training consisted in a daily training during three weeks, 6 days a week, two hours a day, on bicycle ergometer. Eighteen subjects aging 22.2 +/- 1.4 years (11 males, 7 females) were matched in two similar groups: one group trained in normoxic conditions (NG) while the other group (HG) trained with a progressive decrease of the fraction of inspired oxygen (from 12.2% to 10.0%). Maximal oxygen uptake (VO2max) were measured before and after the protocol period in both hypoxic (VO2max H, FIO2 = 10.4%) and normoxic (VO2max N) conditions, for the 2 groups. Training induced a similar O2max N increase in the two groups. The ratio VO2max H/VO2max N was calculated. As expected, in NG group, this ratio decreased significantly (from 63.9 +/- 4.3 to 57.5 +/- 3.1%, p < 0.01) after the training period compared to the initial value, diminution associated with an elevation of VO2max N (from 48.4 +/- 9.0 to 52.9 +/- 9.0 ml.min-1 x kg-1, p < 0.01). Conversely, in HG group, this ratio was not significantly diminished (from 61.7 +/- 3.8 to 60.5 +/- 5.2%, NS) in spite of a similar increase of VO2max N (from 47.5 +/- 5.5 to 50.7 +/- 4.9 ml.min-1 x kg-1, p < 0.01). This does not follow the diminution of the ratio usually described when VO2max N reach higher values.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1483779

  6. Method of and apparatus for measuring the mean concentration of thoron and/or radon in a gas mixture

    DOEpatents

    Lucas, Henry

    1990-01-01

    A method of and an apparatus for detecting and accurately measuring the mean concentrations of .sup.222 Rn and .sup.220 Tn in a gas mixture, such as the ambient atmosphere in a mine, is provided. The apparatus includes an alpha target member which defines at least one operative target surface and which is preferably fabricated from a single piece of an alpha particle sensitive material. At least one portion of the operative target surface is covered with an alpha particle filter. The uncovered and filter covered operative surface is exposed to the gas mixture containing the .sup.222 Rn and .sup.220 Tn. In the radioactive decay series of these isotopes the maximum kinetic energy emitted by the alpha decay of .sup.222 Rn is about 1.1 MeV less than the maximum kinetic energy emitted by the alpha decay of a .sup.220 Tn. The alpha particle filter has a predetermined mass per unit area of the covered portion of the operative target surface that prevents penetration of alpha particles which originate from .sup.222 Rn decay, but which allows passage therethrough of the maximum kinetic energy alpha particles from .sup.220 Tn decay. Thus, a count of the alpha particle tracks in the uncovered portion of the target member is proportional to the mean concentration of sum of .sup.222 Rn and .sup.220 Tn in the gas mixture, while the count of alpha tracks in the target member under the filter is proportional to the concentration of only the .sup.220 Tn in the gas mixture.

  7. Low-pressure equilibrium binary argon-methane gas mixture adsorption on exfoliated graphite: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Albesa, Alberto; Russell, Brice; Vicente, José Luis; Rafti, Matías

    2016-04-01

    Adsorption equilibrium measurements of pure methane, pure argon, and binary mixtures over exfoliated graphite were carried for different initial compositions, temperatures, and total pressures in the range of 0.1-1.5 Torr using the volumetric static method. Diagrams for gas and adsorbed phase compositions were constructed for the conditions explored, and isosteric heats of adsorption were calculated. Experimental results were compared with predictions obtained with Monte Carlo simulations and using the Ideal Adsorbed Solution Theory (IAST).

  8. 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.

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

    SciTech Connect

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

    2014-02-28

    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 C{sub 2}H{sub 5}I. 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. (active media)

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

    SciTech Connect

    Neswal, M.; Gresslehner, K.H.; Lischka, K.

    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.

  11. The transverse viscomagnetic effect in N 2 and N 2-noble gas mixtures in the near hydrodynamic regime

    NASA Astrophysics Data System (ADS)

    Breunese, J. N.; Gödecke, F. W.; Hermans, L. J. F.; Beenakker, J. J. M.

    1984-06-01

    The influence of a magnetic field on the shear viscosity of N 2 and N 2-noble gas mixtures was measured at 295 K in the moderately rarefied gas regime, where the mean free path is non-negligible. For all systems a similar pressure dependence was observed with the Knudsen number providing a universal scaling factor. For pure N 2 it was found that the theory of Waldmann and Vestner describes the pressure dependence very well as long as the boundary layers are well separated (Knudsen number ⪅0.15).

  12. Experimental investigation of a surface DBD plasma actuator at atmospheric pressure in different N2/O2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Audier, P.; Rabat, H.; Leroy, A.; Hong, D.

    2014-12-01

    This paper presents an investigation of the influence of nitrogen and oxygen on the behavior of a surface dielectric barrier discharge (SDBD) used for active flow control. The SDBD operated in a controlled atmosphere under several N2/O2 gas mixture ratios. For each gas mixture, the consumed power was measured as a function of voltage amplitude. Then, for a given applied high voltage, the plasma morphology was recorded and commented and lastly, ionic wind velocity measurements were performed. Results show that the induced ionic wind velocity is mainly due to oxygen negative ions during the negative half-cycle. Nevertheless, the contribution of nitrogen to velocity is not negligible during the positive half-cycle. Moreover, the propagation of negative spark filaments during the negative half-cycle is linked to the proportion of O2 in the gas mixture. Increasing this proportion beyond 20% leads to a shift in the saturation effect to lower voltages and to a decrease in the maximum ionic wind velocity value.

  13. Tunable integration of absorption-membrane-adsorption for efficiently separating low boiling gas mixtures near normal temperature.

    PubMed

    Liu, Huang; Pan, Yong; Liu, Bei; Sun, Changyu; Guo, Ping; Gao, Xueteng; Yang, Lanying; Ma, Qinglan; Chen, Guangjin

    2016-01-01

    Separation of low boiling gas mixtures is widely concerned in process industries. Now their separations heavily rely upon energy-intensive cryogenic processes. Here, we report a pseudo-absorption process for separating low boiling gas mixtures near normal temperature. In this process, absorption-membrane-adsorption is integrated by suspending suitable porous ZIF material in suitable solvent and forming selectively permeable liquid membrane around ZIF particles. Green solvents like water and glycol were used to form ZIF-8 slurry and tune the permeability of liquid membrane surrounding ZIF-8 particles. We found glycol molecules form tighter membrane while water molecules form looser membrane because of the hydrophobicity of ZIF-8. When using mixing solvents composed of glycol and water, the permeability of liquid membrane becomes tunable. It is shown that ZIF-8/water slurry always manifests remarkable higher separation selectivity than solid ZIF-8 and it could be tuned to further enhance the capture of light hydrocarbons by adding suitable quantity of glycol to water. Because of its lower viscosity and higher sorption/desorption rate, tunable ZIF-8/water-glycol slurry could be readily used as liquid absorbent to separate different kinds of low boiling gas mixtures by applying a multistage separation process in one traditional absorption tower, especially for the capture of light hydrocarbons. PMID:26892255

  14. Tunable integration of absorption-membrane-adsorption for efficiently separating low boiling gas mixtures near normal temperature

    NASA Astrophysics Data System (ADS)

    Liu, Huang; Pan, Yong; Liu, Bei; Sun, Changyu; Guo, Ping; Gao, Xueteng; Yang, Lanying; Ma, Qinglan; Chen, Guangjin

    2016-02-01

    Separation of low boiling gas mixtures is widely concerned in process industries. Now their separations heavily rely upon energy-intensive cryogenic processes. Here, we report a pseudo-absorption process for separating low boiling gas mixtures near normal temperature. In this process, absorption-membrane-adsorption is integrated by suspending suitable porous ZIF material in suitable solvent and forming selectively permeable liquid membrane around ZIF particles. Green solvents like water and glycol were used to form ZIF-8 slurry and tune the permeability of liquid membrane surrounding ZIF-8 particles. We found glycol molecules form tighter membrane while water molecules form looser membrane because of the hydrophobicity of ZIF-8. When using mixing solvents composed of glycol and water, the permeability of liquid membrane becomes tunable. It is shown that ZIF-8/water slurry always manifests remarkable higher separation selectivity than solid ZIF-8 and it could be tuned to further enhance the capture of light hydrocarbons by adding suitable quantity of glycol to water. Because of its lower viscosity and higher sorption/desorption rate, tunable ZIF-8/water-glycol slurry could be readily used as liquid absorbent to separate different kinds of low boiling gas mixtures by applying a multistage separation process in one traditional absorption tower, especially for the capture of light hydrocarbons.

  15. Surface modification layer deposition on flexible substrates by plasma-enhanced chemical vapour deposition using tetramethylsilane oxygen gas mixture

    NASA Astrophysics Data System (ADS)

    Wu, Cheng-Yang; Chen, Wen-Cheng; Liu, Day-Shan

    2008-11-01

    Silicon-containing thin films were synthesized from a tetramethylsilane (TMS)-oxygen gas mixture by plasma-enhanced chemical vapour deposition to modify the surface properties of a flexible plastic substrate. The surface wettability was strongly correlated with the presence of hydrocarbon- and hydroxyl-related bonds in the films. The presence of inorganic Si-O-Si networks in the deposited film, originating from an additional oxygen reactant in the glow discharge, significantly increased plastic substrate hardness. Surface uniformity of the inorganic SiOx film varied with mechanical hardness. All such properties were degraded by increased oxygen ion bombardment during the deposition. Additionally, the atomic ratios of O to Si in the deposited films increased at a rate proportional to the oxygen reactant in the gas mixture and brought about a reduction in the optical refractive index. The hard coatings prepared using the TMS-oxygen gas mixture effectively reduced the permeability of the plastic substrate to water vapour. A low water vapour transmission rate was achieved using the film with a high packing density under adequate oxygen ion bombardment.

  16. Tunable integration of absorption-membrane-adsorption for efficiently separating low boiling gas mixtures near normal temperature

    PubMed Central

    Liu, Huang; Pan, Yong; Liu, Bei; Sun, Changyu; Guo, Ping; Gao, Xueteng; Yang, Lanying; Ma, Qinglan; Chen, Guangjin

    2016-01-01

    Separation of low boiling gas mixtures is widely concerned in process industries. Now their separations heavily rely upon energy-intensive cryogenic processes. Here, we report a pseudo-absorption process for separating low boiling gas mixtures near normal temperature. In this process, absorption-membrane-adsorption is integrated by suspending suitable porous ZIF material in suitable solvent and forming selectively permeable liquid membrane around ZIF particles. Green solvents like water and glycol were used to form ZIF-8 slurry and tune the permeability of liquid membrane surrounding ZIF-8 particles. We found glycol molecules form tighter membrane while water molecules form looser membrane because of the hydrophobicity of ZIF-8. When using mixing solvents composed of glycol and water, the permeability of liquid membrane becomes tunable. It is shown that ZIF-8/water slurry always manifests remarkable higher separation selectivity than solid ZIF-8 and it could be tuned to further enhance the capture of light hydrocarbons by adding suitable quantity of glycol to water. Because of its lower viscosity and higher sorption/desorption rate, tunable ZIF-8/water-glycol slurry could be readily used as liquid absorbent to separate different kinds of low boiling gas mixtures by applying a multistage separation process in one traditional absorption tower, especially for the capture of light hydrocarbons. PMID:26892255

  17. 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

  18. Molecular dynamics investigation of separation of hydrogen sulfide from acidic gas mixtures inside metal-doped graphite micropores.

    PubMed

    Huang, Pei-Hsing

    2015-09-21

    The separation of poisonous compounds from various process fluids has long been highly intractable, motivating the present study on the dynamic separation of H2S in acidic-gas-mixture-filled micropores. The molecular dynamics approach, coupled with the isothermal-isochoric ensemble, was used to model the molecular interactions and adsorption of H2S/CO2/CO/H2O mixtures inside metal-doped graphite slits. Due to the difference in the adsorption characteristics between the two distinct adsorbent materials, the metal dopant in the graphitic micropores leads to competitive adsorption, i.e. the Au and graphite walls compete to capture free adsorbates. The effects of competitive adsorption, coupled with changes in the gas temperature, concentration, constituent ratio and slit width on the constituent separation of mixtures were systematically studied. The molecule-wall binding energies calculated in this work (those of H2S, H2O and CO on Au walls and those of H2O, CO and CO2 on graphite walls) show good agreement with those obtained using density functional theory (DFT) and experimental results. The z-directional self-diffusivities (Dz) for adsorbates inside the slit ranged from 10(-9) to 10(-7) m(2) s(-1) as the temperature was increased from 10 to 500 K. The values are comparable with those for a typical microporous fluid (10(-8)-10(-9) m(2) s(-1) in a condensed phase and 10(-6)-10(-7) m(2) s(-1) in the gaseous state). The formation of H-bonding networks and hydrates of H2S is disadvantageous for the separation of mixtures. The results indicate that H2S can be efficiently separated from acidic gas mixtures onto the Au(111) surface by (i) reducing the mole fraction of H2S and H2O in the mixtures, (ii) raising the gas temperature to the high temperature limit (≥400 K), and (iii) lowering the slit width to below the threshold dimension (≤23.26 Å). PMID:26256825

  19. 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 available in OpenFOAM; along with a number of additional features for high temperature, compressible and chemically reacting flows, and k-distribution models for radiative calculations. The radiative transport is solved with the one-dimensional tangent slab and P1 solvers, and also with the two-dimensional P1 solver. The new solver is applied to simulate flow around an entry vehicle in Martian atmosphere. Results for uncoupled and coupled flow-radiation simulations are presented, highlighting the effects of radiative cooling on flowfield and wall fluxes.

  20. Analysis of Trace Gas Mixtures Using an External Cavity Quantum Cascade Laser Sensor

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.; Brumfield, Brian E.; Kriesel, Jason M.

    2015-07-01

    We measure and analyze mixtures of trace gases at ppb-ppm levels using an external cavity quantum cascade laser sensor with a 1-second response time. Accurate spectral fits are obtained in the presence of overlapping spectra.

  1. Study on active radon purification in the XENON100 dark matter detector

    NASA Astrophysics Data System (ADS)

    Weber, Marc; Xenon Collaboration

    2015-04-01

    The radioactive decay of the noble gas element radon presents a substantial background component to current and next generation noble liquid dark matter experiments, which aim at ultra-low background levels to discover interactions of weakly interacting massive particles (WIMPs) in their target. We present first results on an experimental study of active radon removal in the XENON100 detector, using a similar cryogenic distillation technique which has already proven successful in the reduction of krypton in xenon. We are thankful to the National Science Foundation for the continuing support of the XENON dark matter programme.

  2. Chemical shift imaging with continuously flowing hyperpolarized xenon for the characterization of materials.

    PubMed

    Moudrakovski, I L; Lang, S; Ratcliffe, C I; Simard, B; Santyr, G; Ripmeester, J A

    2000-06-01

    In this contribution we report new approaches to the MRI of materials using continuously produced laser-polarized (129)Xe gas. This leads to vastly improved sensitivity and makes new kinds of information available. The hyperpolarized xenon is produced in a continuous flow system that conveniently delivers the xenon at low partial pressure to probes for NMR and MRI experiments. We illustrate applications to the study of micropore and other kinds of void space and show for the first time that with flowing hyperpolarized xenon it is possible to obtain chemical-shift-resolved images in a relatively short time. PMID:10828205

  3. Superheating of liquid xenon in metal tubes

    NASA Astrophysics Data System (ADS)

    Baidakov, V. G.; Kaverin, A. M.

    2009-08-01

    The method of measuring the lifetime has been used to investigate the kinetics of spontaneous boiling-up of superheated xenon in copper tubes. In experiments the temperature dependence of the mean lifetime has been determined at pressures of 1.48 and 1.98 MPa. The data obtained have been compared with homogeneous nucleation theory. It has been found that experimental values of the attainable superheating temperature and the derivative (∂ ln J/∂T)p are systematically lower than their theoretical values. A description of experimental data in the framework of heterogeneous nucleation theory has shown that for the agreement of theory and experiment with the use of a macroscopic model of nucleation on a smooth surface it is necessary to take the value of the equilibrium contact angle θ0 equal to 70°, which is not a characteristic for a xenon-metal system. Taking into account the contribution of the energy of the three-phase contact solid wall-liquid-gas in a microscopic nucleation model makes it possible to reconcile heterogeneous nucleation theory and experimental data at a contact angle θ0 close to zero, with the linear tension taken equal to -6×10-12 J/m and the microscopic contact angle θ∗≃57°. The number of weakened sites, on which bubbles may form, is always smaller than the number of molecules adjacent to the solid wall.

  4. Analytical Modeling of Weld Bead Shape in Dry Hyperbaric GMAW Using Ar-He Chamber Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Azar, Amin S.; Ås, Sigmund K.; Akselsen, Odd M.

    2013-03-01

    Hyperbaric arc welding is a special application of joining the pipeline steels under seawater. In order to analyze the behavior of the arc under ambient pressure, a model is required to estimate the arc efficiency. A distributed point heat source model was employed. The simulated isotherms were calibrated iteratively to fit the actual bead cross section. Basic gas mixture rules and models were used to calculate the thermal properties of the low-temperature shielding gas under the ambient pressure of 10 bar. Nine bead-on-plate welds were deposited each of which under different Ar-He chamber gas compositions. The well-known correlation between arc efficiency (delivered heat) and the thermal conductivity was established for different gas mixtures. The arc efficiency was considered separately for the transverse and perpendicular heat sources. It was found that assigning single heat efficiency factor for the entire arc, which is usually below unity, causes a noticeable underestimation for the heat transfer in the perpendicular direction and a little overestimation in the transverse direction.

  5. 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

  6. Portable mercury gas analyzer with a lamp filled with natural mercury isotope mixture

    NASA Astrophysics Data System (ADS)

    Abramochkin, A. I.; Korolkov, V. A.; Mutnitsky, N. G.; Tatur, V. V.; Tikhomirov, A. A.

    2015-11-01

    Description is presented of a portable mercury gas analyzer operating on the differential absorption method. A gas discharge capillary lamp filled with natural mercury is used as a radiation source. Transverse Zeeman effect is used to get two wavelengths.

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

    NASA Technical Reports Server (NTRS)

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

    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 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. Copyright 1998 Academic Press.

  8. 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.; Rashed, U. M.; Hassouba, M. A.

    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.

  9. 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

  10. Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using gas chromatography-vacuum ultraviolet-mass spectrometry.

    PubMed

    Isaacman, Gabriel; Wilson, Kevin R; Chan, Arthur W H; Worton, David R; Kimmel, Joel R; Nah, Theodora; Hohaus, Thorsten; Gonin, Marc; Kroll, Jesse H; Worsnop, Douglas R; Goldstein, Allen H

    2012-03-01

    Understanding the composition of complex hydrocarbon mixtures is important for environmental studies in a variety of fields, but many prevalent compounds cannot be confidently identified using traditional gas chromatography/mass spectrometry (GC/MS) techniques. This work uses vacuum-ultraviolet (VUV) ionization to elucidate the structures of a traditionally "unresolved complex mixture" by separating components by GC retention time, t(R), and mass-to-charge ratio, m/z, which are used to determine carbon number, N(C), and the number of rings and double bonds, N(DBE). Constitutional isomers are resolved on the basis of t(R), enabling the most complete quantitative analysis to date of structural isomers in an environmentally relevant hydrocarbon mixture. Unknown compounds are classified in this work by carbon number, degree of saturation, presence of rings, and degree of branching, providing structural constraints. The capabilities of this analysis are explored using diesel fuel, in which constitutional isomer distribution patterns are shown to be reproducible between carbon numbers and follow predictable rules. Nearly half of the aliphatic hydrocarbon mass is shown to be branched, suggesting branching is more important in diesel fuel than previously shown. The classification of unknown hydrocarbons and the resolution of constitutional isomers significantly improves resolution capabilities for any complex hydrocarbon mixture. PMID:22304667

  11. 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.

  12. 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.

  13. Surface tension, coexistence curve, and vapor pressure of binary liquid-gas mixtures

    NASA Astrophysics Data System (ADS)

    Do, V. T.; Straub, J.

    1986-01-01

    The objective of this paper is to present measurements of the vapor pressure, capillary coefficient, and refractive index of four binary mixtures, CO2-SF6, R14-SF6, SF6-R13B1, and SF6-R22, at liquid-vapor equilibrium at different average concentrations. The measuring temperature range covered the entire liquid-vapor region from the triple line up to the critical point. The capillary coefficient was determined by means of the capillary rise method; the refractive index, by measuring the angle of refraction of a light beam passing through a prism and the sample. In order to obtain the liquid-vapor densities of pure substances the Lorentz-Lorenz relation can be used. However, in applying this relation to calculate the liquid-vapor densities of a mixture, one may need the concentrations of both the liquid and the vapor phase, which are, for the most part, quite different from the average concentration of the mixture. Calculating the concentrations of both fluid phases with the aid of an equation of state and comparing with measurements, we could show that the molar refraction coefficient of the mixtures can be simply determined from the average concentration and the molar refraction coefficients of their pure components. The surface tension of the mixtures could then be calculated from the measured capillary coefficient and the refractive index with the aid of the Lorentz-Lorenz relation.

  14. 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

  15. Combustion of hydrogen-based mixtures in gas-fueled reciprocating engines

    NASA Astrophysics Data System (ADS)

    Smygalina, A. E.; Zaitchenko, V. M.; Ivanov, M. F.; Kiverin, A. D.

    2015-12-01

    The research is devoted to the possibility for application of hydrogen accumulated from renewable energy sources as a fuel for a reciprocating engine, which serves as an electrical generator drive. Hydrogen combustion in the chamber of a reciprocating engine, as a rule, occurs in a detonation mode. In order to obtain less hard modes, the present research proposes the usage of steam additions to hydrogen-air mixture or lean hydrogen-air mixtures. Mathematical simulation is used for investigation of combustion of mentioned mixtures in the combustion chamber of a reciprocating engine with a spark-plug ignition. The comparison of the usage of hydrogen-steam-air mixtures and lean hydrogen-air mixtures as fuels is given. The dependence of arising combustion modes and its quantitative characteristics on hydrogen content in combustible composition is investigated. The analysis of optimal combustion is presented, which is based on the consideration of two parameters: peak pressure in one cycle and the crankshaft angle corresponding to the achievement of the peak pressure.

  16. Development of traceable precision dynamic dilution method to generate dimethyl sulphide gas mixtures at sub-nanomole per mole levels for ambient measurement.

    PubMed

    Kim, Mi Eon; Kim, Yong Doo; Kang, Ji Hwan; Heo, Gwi Suk; Lee, Dong Soo; Lee, Sangil

    2016-04-01

    Dimethyl sulphide (DMS) is an important compound in global atmospheric chemistry and climate change. Traceable international standards are essential for measuring accurately the long-term global trend in ambient DMS. However, developing accurate gas standards for sub-nanomole per mole (nmol/mol) mole fractions of DMS in a cylinder is challenging, because DMS is reactive and unstable. In this study, a dynamic dilution method that is traceable and precise was developed to generate sub-nmol/mol DMS gas mixtures with a dynamic dilution system based on sonic nozzles and a long-term (>5 years) stable 10μmol/mol parent DMS primary standard gas mixtures (PSMs). The dynamic dilution system was calibrated with traceable methane PSMs, and its estimated dilution factors were used to calculate the mole fractions of the dynamically generated DMS gas mixtures. A dynamically generated DMS gas mixture and a 6nmol/mol DMS PSM were analysed against each other by gas chromatography with flame-ionisation detection (GC/FID) to evaluate the dilution system. The mole fractions of the dynamically generated DMS gas mixture determined against a DMS PSM and calculated with the dilution factor agreed within 1% at 6nmol/mol. In addition, the dynamically generated DMS gas mixtures at various mole fractions between 0.4 and 11.7nmol/mol were analysed by GC/FID and evaluated for their linearity. The analytically determined mole fractions showed good linearity with the mole fractions calculated with the dilution factors. Results showed that the dynamic dilution method generates DMS gas mixtures ranging between 0.4nmol/mol and 12nmol/mol with relative expanded uncertainties of less than 2%. Therefore, the newly developed dynamic dilution method is a promising reference method for generating sub-nmol/mol DMS gas standards for accurate ambient measurements. PMID:26838438

  17. Coherent and spontaneous Rayleigh-Brillouin scattering in atomic and molecular gases and gas mixtures

    SciTech Connect

    Vieitez, M. O.; Duijn, E. J. van; Ubachs, W.; Witschas, B.; Meijer, A.; Wijn, A. S. de; Dam, N. J.; Water, W. van de

    2010-10-15

    We study Rayleigh-Brillouin scattering in gases of N{sub 2}, O{sub 2}, and SF{sub 6} molecules, Kr atoms, and He-Xe and He-CO{sub 2} mixtures at pressures ranging from 1 to 3 bar and using two different experimental setups. In one setup, we measure spectra of light scattered by thermal density fluctuations (spontaneous Rayleigh-Brillouin scattering); in the second setup density waves are induced in the overlap region of two counterpropagating laser beams (coherent Rayleigh-Brillouin scattering). We compare measured spectra to the Tenti models and to a recent model for mixtures. We find new values of the bulk viscosity, which is a parameter in line-shape models that allows for internal degrees of freedom. Both experiments agree on the value of the bulk viscosity. Our results indicate a need for new line-shape models for mixtures of molecules with internal degrees of freedom.

  18. Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with neon

    SciTech Connect

    Malinina, A. A. Malinin, A. N.

    2013-12-15

    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{sup −14} m{sup 3}/s for a reduced electric field of E/N = 15 Td, at which the maximum emission intensity in the blue-green spectral region (λ{sub max} = 502 nm) was observed in this experiment.

  19. 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.

  20. Terrestrial and Martian weathering signatures of xenon components in shergottite mineral separates

    NASA Astrophysics Data System (ADS)

    Cartwright, J. A.; Ocker, K. D.; Crowther, S. A.; Burgess, R.; Gilmour, J. D.

    2010-08-01

    Xenon-isotopic ratios, step-heating release patterns, and gas concentrations of mineral separates from Martian shergottites Roberts Massif (RBT) 04262, Dar al Gani (DaG) 489, Shergotty, and Elephant Moraine (EET) 79001 lithology B are reported. Concentrations of Martian atmospheric xenon are similar in mineral separates from all meteorites, but more weathered samples contain more terrestrial atmospheric xenon. The distributions of xenon from the Martian and terrestrial atmospheres among minerals in any one sample are similar, suggesting similarities in the processes by which they were acquired. However, in opaque and maskelynite fractions, Martian atmospheric xenon is released at higher temperatures than terrestrial atmospheric xenon. It is suggested that both Martian and terrestrial atmospheric xenon were initially introduced by weathering (low temperature alteration processes). However, the Martian component was redistributed by shock, accounting for its current residence in more retentive sites. The presence or absence of detectable 129Xe from the Martian atmosphere in mafic minerals may correspond to the extent of crustal contamination of the rock's parent melt. Variable contents of excess 129Xe contrast with previously reported consistent concentrations of excess 40Ar, suggesting distinct sources contributed these gases to the parent magma.

  1. A comparison of solar wind and estimated solar system xenon abundances - A test for solid/gas fractionation in the solar nebula

    NASA Technical Reports Server (NTRS)

    Wiens, Roger C.; Burnett, D. S.; Neugebauer, M.; Pepin, R. O.

    1992-01-01

    The solar Xe elemental abundance is determined here using solar wind measurements from lunar ilmenites which are normalized to Si by spacecraft data. The results are compared with estimated abundances assuming no fractionation. When corrected for solar wind/photospheric fractionation, the Xe-130 abundance given by surface layer oxidation of ilmenite from solid 71501 exposed within the last 200 m.y. is 0.24 +/- 0.09 normalized to Si = 10 exp 6. This is indistinguishable from estimates made assuming no solid/gas fractionation. Results from breccia 79035 ilmenite exposed at least 1 Gyr ago indicate that the solar wind Xe flux may have been significantly higher relative to other noble gases, perhaps due to more efficient Xe ionization. If this is true, fluxes of C and S, which have first ionization potentials similar to Xe, should also be higher in the ancient solar wind from the same time period.

  2. Endocrine-Disrupting Chemicals and Oil and Natural Gas Operations: Potential Environmental Contamination and Recommendations to Assess Complex Environmental Mixtures

    PubMed Central

    Kassotis, Christopher D.; Tillitt, Donald E.; Lin, Chung-Ho; McElroy, Jane A.; Nagel, Susan C.

    2015-01-01

    Background Hydraulic fracturing technologies, developed over the last 65 years, have only recently been combined with horizontal drilling to unlock oil and gas reserves previously deemed inaccessible. Although these technologies have dramatically increased domestic oil and natural gas production, they have also raised concerns for the potential contamination of local water supplies with the approximately 1,000 chemicals that are used throughout the process, including many known or suspected endocrine-disrupting chemicals. Objectives We discuss the need for an endocrine component to health assessments for drilling-dense regions in the context of hormonal and antihormonal activities for chemicals used. Methods We discuss the literature on a) surface and groundwater contamination by oil and gas extraction operations, and b) potential human exposure, particularly in the context of the total hormonal and antihormonal activities present in surface and groundwater from natural and anthropogenic sources; we also discuss initial analytical results and critical knowledge gaps. Discussion In light of the potential for environmental release of oil and gas chemicals that can disrupt hormone receptor systems, we recommend methods for assessing complex hormonally active environmental mixtures. Conclusions We describe a need for an endocrine-centric component for overall health assessments and provide information supporting the idea that using such a component will help explain reported adverse health trends as well as help develop recommendations for environmental impact assessments and monitoring programs. Citation Kassotis CD, Tillitt DE, Lin CH, McElroy JA, Nagel SC. 2016. Endocrine-disrupting chemicals and oil and natural gas operations: potential environmental contamination and recommendations to assess complex environmental mixtures. Environ Health Perspect 124:256–264; http://dx.doi.org/10.1289/ehp.1409535 PMID:26311476

  3. Characteristics of a cylindrical collector mirror for laser-produced xenon plasma soft X-rays and improvement of mirror lifetime by buffer gas

    SciTech Connect

    Inoue, Tomoaki; Mochizuki, Takayasu; Miyamoto, Shuji; Masuda, Kazuya; Amano, Sho; Kanda, Kazuhiro

    2012-12-15

    The focusing characteristics of a ruthenium-coated cylindrical mirror were investigated on the basis of its ability to collect and focus broadband 5-17-nm soft X-rays emitted from a laser-produced plasma. Based on the plasmas spectral intensity distribution and the reflectivity function of the mirror, we defined the optimum position of the integrated cylindrical mirror at which the X-ray energy flux transported and focused through the mirror was maximum. A minimum spot diameter of 22 mm at a distance of approximately 200 mm from a soft X-ray source was confirmed. The maximum intensity of the collected soft X-rays was 1.3 mJ/cm{sup 2} at the center of the irradiation zone. Thus, the irradiation intensity was improved by approximately 27 times when compared to that of 47 {mu}J/cm{sup 2} without the mirror. The debris sputtering rate on the reflection surface of the mirror can be reduced to 1/110 by argon gas at 11 Pa, while the attenuation rate of the soft X-rays due to absorption by the buffer gas can be suppressed to less than 10% at the focal point. The focusing property of the mirror is expected to be maintained for 3000 h or longer without significant degradation for a 100 W/320 pps laser shot if the ruthenium layer is thicker than 10 {mu}m. These results suggest that a stand-alone broadband soft X-ray processing system can be realized by using laser-produced plasma soft X-rays.

  4. High Pressure XENON Gamma-Ray Spectrometers for Field Use

    SciTech Connect

    David K. Wehe; Zong He; Glenn K. Knoll

    2004-02-16

    This project explored a new concept for high-pressure xenon ionization chambers by replacing the Frisch grid with coplanar grid electrodes similar to those used in wide bandgap semiconductor gamma-ray spectrometers. This work is the first attempt to apply the coplanar grid anode design in a gas ionization chamber in order to achieve to improved energy resolution. Three prototype detectors, two cylindrical and one parallel plate configurations, were built and tested. While the detectors did not demonstrate energy resolutions as good as other high pressure xenon gamma-ray spectrometers, the results demonstrated that the concept of single polarity charge sending using coplanar grid electrodes will work in a gas detector.

  5. On the Equipartition of Kinetic Energy in an Ideal Gas Mixture

    ERIC Educational Resources Information Center

    Peliti, L.

    2007-01-01

    A refinement of an argument due to Maxwell for the equipartition of translational kinetic energy in a mixture of ideal gases with different masses is proposed. The argument is elementary, yet it may work as an illustration of the role of symmetry and independence postulates in kinetic theory. (Contains 1 figure.)

  6. Fission Xenon on Mars

    NASA Technical Reports Server (NTRS)

    Mathew, K. J.; Marti, K.; Marty, B.

    2002-01-01

    Fission Xe components due to Pu-244 decay in the early history of Mars have been identified in nakhlites; as in the case of ALH84001 and Chassigny the fission gas was assimilated into indigenous solar-type Xe. Additional information is contained in the original extended abstract.

  7. 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.

  8. Laboratory measurements and modeling of microwave absorption by ammonia in gas mixtures applicable to giant planet atmospheres

    NASA Technical Reports Server (NTRS)

    Spilker, T. R.

    1990-01-01

    Accurate knowledge of the microwave absorption behavior of ammonia is critical to the correct interpretation of radio astronomical and radio occultation data from the giant planets. New cavity resonator techniques developed at the Stanford Center for Radar Astronomy have allowed accurate laboratory measurements of the microwave absorptivity and refractivity spectra of gas mixtures containing trace amounts of ammonia. A parameterized version of the modified Ben-Reuven formalism of Berge and Bulkis was optimized to fit the new data. The new formalism produced by this method predicts ammonia absorptivity much more accurately than previous formalism over a significant range of conditions.

  9. High harmonic generation in a Xe-He gas mixture driven by kHz tightly focused laser pulses

    NASA Astrophysics Data System (ADS)

    Lu, F. M.; Xia, Y. Q.; Zhang, S.; Chen, D. Y.

    2013-11-01

    High harmonic generation and its spectral properties are studied by using kHz tightly focused laser pulses in a Xe-He gas mixture. The cutoff region of harmonics in mixed gases is extended from H21 to H25. The results are attributed to the harmonic generation from the excited He atoms assisted by harmonic radiation from the Xe atoms. We illustrate that the pressure dependence of harmonic H19 shows a flat intensity profile in mixed gases. The results are explained by the harmonic H19 being moved from the cutoff region to a plateau region.

  10. Beam and ageing tests with a highly saturated avalanche gas mixture for the ALICE p p data taking

    NASA Astrophysics Data System (ADS)

    Arnaldi, R.; Baldit, A.; Barret, V.; Bastid, N.; Blanchard, G.; Chiavassa, E.; Colla, A.; Cortese, P.; Crochet, P.; Dellacasa, G.; Devaux, A.; De Marco, N.; Dupieux, P.; Ferretti, A.; Force, P.; Forestier, B.; Gagliardi, M.; Gallio, M.; Gemme, R.; Grigoryan, S.; Guerin, F.; Guernane, R.; Insa, C.; Jouve, F.; Manso, F.; Mereu, P.; Musso, A.; Oppedisano, C.; Piccotti, A.; Poggio, F.; Royer, L.; Rosnet, P.; Saturnini, P.; Scomparin, E.; Travaglia, G.; Vercellin, E.; Yermia, F.

    2006-08-01

    The trigger detectors for the Muon Forward Spectrometer of the ALICE experiment will be single gap RPCs with low-resistivity bakelite electrodes. The detector will take data for different colliding systems resulting in a wide range of working conditions and requirements, especially concerning position resolution and detector lifetime. To this aim we have investigated the possibility to operate the RPCs both in streamer and in highly-saturated avalanche mode with the same FE electronics. In this paper we present the results obtained in a test with cosmic rays, as well as from beam and ageing tests with the gas mixture that allows for highly-saturated avalanche operation.

  11. Quench gases for xenon- (and krypton-) filled proportional counters

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    Xenon-filled proportional counters are used extensively in astronomy, particularly in the hard X-ray region. The choice of quench gas can have a significant effect on the operating characteristics of the instrument although the data necessary to make the choice are not easily obtainable. Results which detail the performance obtained from both cylindrical and parallel field geometries for a wide variety of readily available, ultrahigh or research grade purity, quench gases are presented.

  12. Study of pulsed neon-xenon VUV radiating low pressure plasmas for mercury free fluorescent sign optimization

    NASA Astrophysics Data System (ADS)

    Robert, E.; Point, S.; Dozias, S.; Viladrosa, R.; Pouvesle, J. M.

    2010-04-01

    This work deals with the study and optimization of mercury free fluorescent discharge tubes for publicity lighting applications. The experimental set-up allows for time resolved spectroscopy from 110 up to 900 nm, photometric characterization in a large volume integrating sphere and the current and voltage measurement of microsecond duration signals delivered by lab-developed pulsed drivers. The glow and afterglow radiative process analysis indicates that the best performance measured with the pulsed excitation of rare gas plasma, in comparison with the conventional ac excitation, essentially originates from the efficient plasma relaxation during the afterglow at the benefit of the vacuum ultraviolet (VUV) resonance line radiated at 146.9 nm for xenon. The fit of the VUV time resolved experimental measurements, with the results issued from a simplified kinetic model of neon-xenon plasmas, evidences the crucial role of production of molecular ions during the glow phase and of their radiative recombination during the afterglow. The pulse duration and the gas mixture pressure appear as two experimental parameters whose influence, studied over an extended range, has been demonstrated to bring about a significant sign performance enhancement. There exists an optimum pulse duration range, which results in the appearance of limited stepwise excitation and ionization processes, favourable for an intense afterglow VUV production. The pressure dependence study shows that the best performance for pulsed excitation is obtained in Ne/Xe (100/1) mixtures around 50 mbar, at the difference of an ac driven Ne/Xe plasma for which the best conditions were reported to be of a few millibars. This pressure increase results both in the VUV and sign light output enhancement and the successful continuous operation of pulsed mercury free signs for time as long as 4000 h with neither electrode erosion, nor glass or phosphor degradation nor chromatic coordinate variation. For the green phosphor covered, 65 cm long and 13 mm inner diameter signs, the efficiency of a pulsed neon-xenon discharge likely to be operated for a few thousand hours reaches 50% of that of the same tube filled with mercury based mixtures.

  13. 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.

  14. Selective denitrification of flue gas by O3 and ethanol mixtures in a duct: Investigation of processes and mechanisms.

    PubMed

    Ding, Jie; Cai, Heruijing; Zhong, Qin; Lin, Jiandong; Xiao, Junjun; Zhang, Shule; Fan, Maohong

    2016-07-01

    A novel selective denitrification process, referred as O3-ethanol oxidation method, was developed by injecting O3 and ethanol mixtures into the simulated flue gas duct. The organic radicals, generated through the ethanol oxidation by O3, can oxidize NO into NO2, and finally into important industrial raw, namely, nitrate organics or aqueous nitrate acids. The residual ethanol in the tail can be recycled. The CO3(2-), HCO3(-) and SO2 in the flue gas hardly exhibit any effect on the NOX removal. Compared to the conventional O3 oxidation method, the present method shows higher selective oxidation of NO, higher NOX removal and less O3 consumption as well as proves lower initial investment and operating costs with more compact equipment. PMID:26989982

  15. Gas-phase ion chemistry in germane-propane and germane-propene mixtures.

    PubMed

    Benzi, Paola; Operti, Lorenza; Rabezzana, Roberto; Vaglio, Gian Angelo

    2002-06-01

    Germane-propane and germane-propene gaseous mixtures were studied by ion trap mass spectrometry. Variations of ion abundances observed under different partial pressure ratios and mechanisms of ion-molecule reactions elucidated by multiple isolation steps are reported. In addition, the rate constants for the main reactions were experimentally determined and compared with the collisional rate constants to obtain the reaction efficiencies. The yield of ions containing both Ge and C atoms is higher in the germane-propene than in the germane-propane system. In the former mixture, chain propagation takes place starting from germane ions reacting with propene and proceeds with the formation of clusters such as Ge(2)C(4)H(n) (+) and Ge(3)CH(n) (+). PMID:12112742

  16. Reacting gas mixtures in the state-to-state approach: The chemical reaction rates

    SciTech Connect

    Kustova, Elena V.; Kremer, Gilberto M.

    2014-12-09

    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 N{sub 2} 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.

  17. Quantitative prediction of thermal diffusion in gas mixtures by use of thermodynamics

    SciTech Connect

    Guy, A.G.

    1980-12-01

    Separation of isotopes by gaseous thermal diffusion is of basic importance for both nuclear science and for the development of nuclear energy. The present unsatisfactory state of the theory is shown by the fact that the experimental behavior of a 50/50 mixture of carbon dioxide and argon has remained unexplained for 30 years. This system is used as an example of the application of a new thermodynamic approach to thermal diffusion in gases. The thermal diffusion ratio is calculated as the sum of two terms. The first is determined from present momentum-exchange theory for the hypothetical non-interacting molecules. The second term takes account of the effect of interaction by use of the excess entropy of the mixture of gases. The excess entropy is calculated from the virial coefficients of the equation of state.

  18. Cylindrical Couette flow of a vapor-gas mixture: Ghost effect and bifurcation in the continuum limit

    NASA Astrophysics Data System (ADS)

    Yoshida, Hiroaki; Aoki, Kazuo

    2006-08-01

    A binary mixture of gases is confined in a gap between two coaxial circular cylinders rotating at different angular velocities. One of the component gases is the vapor of the substance that forms the cylinders, so that evaporation or condensation (or sublimation) of the vapor may take place on the surfaces of the cylinders. The other component is a noncondensable gas that neither evaporates nor condenses on the surfaces. Axisymmetric and axially uniform flows (the cylindrical Couette flow) of such a mixture are investigated on the basis of kinetic theory with special interest in the continuum (or fluid-dynamic) limit in which the Knudsen number goes to zero. The fluid-dynamic system that describes the behavior of the mixture is derived by a formal but systematic asymptotic analysis of the Boltzmann system. The resulting system shows some nontrivial phenomena such as the ghost effect and the flow bifurcation. These phenomena are also demonstrated by a Monte Carlo simulation for small Knudsen numbers using the Boltzmann equation.

  19. Laser-induced fluorescence measurements of argon and xenon ion velocities near the sheath boundary in 3 ion species plasmas

    NASA Astrophysics Data System (ADS)

    Yip, Chi-Shung; Hershkowitz, Noah; Severn, Greg; Baalrud, Scott D.

    2016-05-01

    The Bohm sheath criterion is studied with laser-induced fluorescence in three ion species plasmas using two tunable diode lasers. Krypton is added to a low pressure unmagnetized DC hot filament discharge in a mixture of argon and xenon gas confined by surface multi-dipole magnetic fields. The argon and xenon ion velocity distribution functions are measured at the sheath-presheath boundary near a negatively biased boundary plate. The potential structures of the plasma sheath and presheath are measured by an emissive probe. Results are compared with previous experiments with Ar-Xe plasmas, where the two ion species were observed to reach the sheath edge at nearly the same speed. This speed was the ion sound speed of the system, which is consistent with the generalized Bohm criterion. In such two ion species plasmas, instability enhanced collisional friction was demonstrated [Hershkowitz et al., Phys. Plasmas 18(5), 057102 (2011).] to exist which accounted for the observed results. When three ion species are present, it is demonstrated under most circumstances the ions do not fall out of the plasma at their individual Bohm velocities. It is also shown that under most circumstances the ions do not fall out of the plasma at the system sound speed. These observations are also consistent with the presence of the instabilities.

  20. Characterization of a GEM-based scintillation detector with He–CF4 gas mixture in clinical proton beams

    NASA Astrophysics Data System (ADS)

    Nichiporov, D.; Coutinho, L.; Klyachko, A. V.

    2016-04-01

    Accurate, high-spatial resolution dosimetry in proton therapy is a time consuming task, and may be challenging in the case of small fields, due to the lack of adequate instrumentation. The purpose of this work is to develop a novel dose imaging detector with high spatial resolution and tissue equivalent response to dose in the Bragg peak, suitable for beam commissioning and quality assurance measurements. A scintillation gas electron multiplier (GEM) detector based on a double GEM amplification structure with optical readout was filled with a He/CF4 gas mixture and evaluated in pristine and modulated proton beams of several penetration ranges. The detector’s performance was characterized in terms of linearity in dose rate, spatial resolution, short- and long-term stability and tissue-equivalence of response at different energies. Depth-dose profiles measured with the GEM detector in the 115–205 MeV energy range were compared with the profiles measured under similar conditions using the PinPoint 3D small-volume ion chamber. The GEM detector filled with a He-based mixture has a nearly tissue equivalent response in the proton beam and may become an attractive and efficient tool for high-resolution 2D and 3D dose imaging in proton dosimetry, and especially in small-field applications.