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1

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

NASA Technical Reports Server (NTRS)

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.

Johnson, Paul K.

2006-01-01

2

Thermodynamics of Liquid Mixtures of Xenon with Alkanes: (Xenon + n-Butane) and (Xenon + Isobutane)  

E-print Network

The total vapor pressure of liquid mixtures of (xenon + n-butane) has been measured at 182.34 and 195.49 K, and of (xenon + isobutane) at 195.49 K. The liquid molar volumes have also been measured at 182.34 K for both systems. The mixtures follow the behavior already found for other (xenon + alkane) mixtures, i.e., E negative deviations from Raoult’s law, negative excess molar Gibbs energies (Gm) and negative excess molar

Eduardo J. M. Filipe; Luís F. G. Martins; Jorge C. G. Calado; Clare Mccabe; George Jackson

1999-01-01

3

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

E-print Network

A technical description of NEXT-MM and its commissioning and first performance is reported. Having an active volume of ~35 cm drift $\\times$ 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 trimethylamine (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.

Álvarez, V; Borges, F I G M; Calvet, D; Cárcel, S; Castel, J; Cebrián, S; Cervera, A; Conde, C A N; Dafni, T; Dias, T H V T; Díaz, 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; Gómez, H; Gómez-Cadenas, J J; González-Díaz, D; Gutiérrez, R M; Hauptman, J; Morata, J A Hernando; Herrera, D C; Iguaz, F J; Irastorza, I G; Jinete, M A; Labarga, L; Laing, A; Coguie, A Le; Liubarsky, I; Lopes, J A M; Lorca, D; Losada, M; Luzón, G; Marí, A; Martín-Albo, J; Martínez, A; Martínez-Lema, G; Miller, T; Moiseenko, A; Mols, J P; Monrabal, F; Monteiro, C M B; Mora, F J; Moutinho, L M; Vidal, J Muñoz; da Luz, H Natal; Navarro, G; Nebot-Guinot, M; Nygren, D; Oliveira, C A B; Palma, R; Pérez, J; Aparicio, J L Pérez; Renner, J; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, P; Santos, J M F dos; Segui, L; Serra, L; Shuman, D; 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 T; Yahlali, N

2013-01-01

4

RELAXATION PROCESSES OF Xe*(3P2) METASTABLE ATOMS IN ARGON-XENON MIXTURES  

E-print Network

L- 105 RELAXATION PROCESSES OF Xe*(3P2) METASTABLE ATOMS IN ARGON-XENON MIXTURES M. CHENEVIER, N*(3P2) by two-body collisions with argon k3, and by three-body collisions with an argon and a xenon Abstracts 34.50H - 82.20 Introduction. - Recently several types of xenon halide excimer laser have been

Paris-Sud XI, Université de

5

XENON  

Microsoft Academic Search

The XENON experiment aims at the direct detection of dark matter in the form of WIMPs (Weakly Interacting Massive Particles) via their elastic scattering off Xenon nuclei. With 1 ton of LXe distributed in ten identical modules, the proposed XENON1T experiment will achieve a sensitivity more than a factor of thousand beyond current limits.The detectors are time projection chambers operated

E. Aprile; K.-L. Giboni; M. E. Monzani; G. Plante; M. Yamashita; R. J. Gaitskell; S. Fiorucci; P. Sorensen; L. Deviveiros; A. Bernstein; N. Madden; C. Winant; T. Shutt; J. Kwong; A. Bolozdynya; E. Dahl; U. Oberlack; P. Shagin; R. Gomez; D. McKinsey; A. Manzur; R. Hasty; K. Ni; F. Arneodo; A. Ferella; L. Baudis; J. Angle; J. Orboeck; A. Manalaysay; J. A. M. Lopes; L. Coelho; L. Fernandes; J. Santos

2007-01-01

6

X-ray diffraction of krypton and xenon mixtures adsorbed on graphite T. Ceva, M. Goldmann (*) and C. Marti  

E-print Network

1527 X- ray diffraction of krypton and xenon mixtures adsorbed on graphite T. Ceva, M. Goldmann 1986) Résumé. 2014 En étudiant, par diffraction des rayons X, les mélanges xenon-krypton absorbés sur. Abstract 2014 Mixtures of xenon and krypton adsorbed on graphite at 45 K are studied by X ray diffraction

Boyer, Edmond

7

Gas-phase silicon micromachining with xenon difluoride  

Microsoft Academic Search

Xenon difluoride is a gas phase, room temperature, isotropic silicon etchant with extremely high selectivity to many materials commonly used in microelectromechancial systems, including photoresists, aluminum, and silicon dioxide. Using a simple vacuum system, the effects of etch aperture and loading were explored for etches between 10 and 200 micrometers . Etch rates as high as 40 micrometers \\/minute were

Floy I. Chang; Richard Yeh; Gisela Lin; Patrick B. Chu; Eric G. Hoffman; Ezekiel J. Kruglick; Kristofer S. Pister; Michael H. Hecht

1995-01-01

8

A xenon gas purity monitor for EXO , C. Hall a,n  

E-print Network

A xenon gas purity monitor for EXO A. Dobi a , C. Hall a,n , S. Herrin b , A. Odian b , C September 2011 Available online 19 September 2011 Keywords: Xenon Electronegative ion Purification Tungsten versions of a xenon gas purity monitor (GPM) developed for the EXO double beta decay program. The devices

Gratta, Giorgio

9

Diffusion NMR methods applied to xenon gas for materials study  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

10

Penning gas mixtures for improving the energy resolution of proportional counters  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

11

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

Microsoft Academic Search

The VUV spectrum of gaseous mixtures of krypton with a small amount of xenon added was investigated in the range 115–200 nm.\\u000a The mixtures were excited in a capillary DC discharge where the capillary could be cooled by using liquid nitrogen. The mixed\\u000a molecule band around the Xe I resonance line at ? = 147 nm and the mixed molecule

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

2000-01-01

12

Characteristic parameters of xenon near its liquid-gas critical point Yves Garrabos and Carole Lecoutre  

E-print Network

Characteristic parameters of xenon near its liquid-gas critical point Yves Garrabos and Carole the singular behaviors of the isothermal compressibility of xenon along the critical isochore in the homogeneous domain and the vapor-liquid coexisting densities of xenon in the nonhomogenous domain

Boyer, Edmond

13

Numerical model of an ac plasma display panel cell in neon-xenon mixtures  

Microsoft Academic Search

We present a self-consistent 1D model of the discharge initiated in an ac plasma display panel cell. The model is based on a two-moments fluid description of electron and ion transport, coupled with Poisson’s equation, and with a set of kinetic equations characterizing the evolution of the population of excited states leading to UV emission in neon-xenon mixtures. Results are

J. Meunier; Ph. Belenguer; J. P. Boeuf

1995-01-01

14

New gas mixtures suitable for rare event detection using a Micromegas-TPC detector  

E-print Network

The aim of the presented work was to develop further techniques based on a Micromegas-TPC, in order to reach a high gas gain with good energy resolution, and to search for gas mixtures suitable for rare event detection. This paper focuses on xenon, which is convenient for the search of neutrinoless double beta decay in 136 Xe. Conversely, a small admixture of xenon to CF 4 can reduce attachment in the latter. This gas mixture would be suitable for dark matter searches and the study of solar and reactor neutrinos. Various configurations of the Micromegas plane were investigated and are described.

L. Ounalli; J-L. Vuilleumier; D. Schenker; J-M. Vuilleumier

2008-12-29

15

Mobility and fluorescence of barium ions in xenon gas for the exo experiment  

NASA Astrophysics Data System (ADS)

The Enriched Xenon Observatory (EXO) is an experiment which aims to observe the neutrinoless double beta decay of 136Xe. The measurement of this decay would give information about the absolute neutrino mass and whether or not the neutrino is its own antiparticle. Since this is a very rare decay, the ability to reject background events by detecting the barium ion daughter from the double beta decay would be a major advantage. EXO is currently operating a detector with 200 kg of enriched liquid xenon, and there are plans to build a ton scale xenon detector. Measurements of the purity of liquid xenon in our liquid xenon test cell are reported. These results are relevant to the research on detection of single barium ions by our research group at Colorado State University. Details of the operation of the purity monitor are described. The effects of using a purifier, recirculation and laser ablation on the purity of liquid xenon are discussed. Mobility measurements of barium in xenon gas are reported for the first time. The variation of mobility with xenon gas pressure suggests that a significant fraction of molecular ions are formed when barium ions interact with xenon gas at high pressures. The measured mobility of Ba+ in Xe gas at different pressures is compared with the predicted theoretical value, and deviations are explained by a model that describes the fraction of molecular ions in Xe gas as a function of pressure. The results are useful for the analysis of experiments of fluorescence of Ba+ in xenon gas. It is also important to know the mobility of the ions in order to calculate the time they interact with an excitation laser in fluorescence experiments and in proposed 136 Ba+ daughter detection schemes. This thesis presents results of detection of laser induced fluorescence of Ba+ ions in Xe gas. Measurements of the pressure broadening of the excitation spectra of Ba+ in xenon gas are presented. Nonradiative decays due to gas collisions and optical pumping affect the number of fluorescence counts detected. A model that treats the barium ion as a three level system is used to predict the total number of fluorescence counts and correct for optical pumping. A pressure broadening coefficient for Ba+ in xenon gas is extracted and limits for p-d and d-s nonradiative decay rates are extracted. Although fluorescence is reduced significantly at 5-10 atm xenon pressure, the measurements in this thesis indicate that it is still feasible to detect 136Ba+ ions directly in high pressure xenon gas, e.g. in a double beta decay detector.

Benitez Medina, Julio Cesar

16

Helium, neon, argon, krypton and xenon in gas emanations from Yellowstone and Lassen volcanic National Parks  

Microsoft Academic Search

The abundance of helium, neon, argon, krypton and xenon were measured in gas emanations from thermal springs in Yellowstone National Park, Wyoming and Lassen National Park, California. The determinations were made using an isotope dilution procedure. The isotopic composition of argon and the relative abundances of argon, neon, krypton and xenon indicate that these gases originated from the atmosphere through

E. Mazor; G. J. Wasserburg

1965-01-01

17

Human Regional Pulmonary Gas Exchange with Xenon Polarization Transfer (XTC)  

NASA Astrophysics Data System (ADS)

Xenon Transfer Contrast (XTC) is an existing imaging method (Ruppert et al, Magn Reson Med, 51:676-687, 2004) that measures the fraction F of ^129Xe magnetization that diffuses from alveolar gas spaces to septal parenchymal tissue in lungs in a specified exchange time. As previously implemented, XTC is a 2-breath method and has been demonstrated in anesthetized animals. To use XTC in humans and to avoid issues associated with obtaining identical gas volumes on subsequent breath-hold experiments as well as precise image registration in post-processing, a single breath XTC method was developed that acquires three consecutive gradient echo images in an 8s acquisition. We report here initial measurements of the mean and variance of F for 5 normal healthy subjects as well as 7 asymptomatic smokers. The experiments were performed at two lung volumes (˜45 and 65% of TLC). We found that both the mean and variance of F increased with smoking history. In comparison, standard pulmonary function tests such as DLCO FEV1 showed no correlation with smoking history.

Muradian, Iga; Butler, James; Hrovat, Mirko; Topulos, George; Hersman, Elizabeth; Ruset, Iulian; Covrig, Silviu; Frederick, Eric; Ketel, Stephen; Hersman, F. W.; Patz, Samuel

2007-03-01

18

Neuroprotective and neurotoxic properties of the 'inert' gas, xenon  

Microsoft Academic Search

Background. Antagonists of the N-methyl-D-aspartate (NMDA) subtype of glutamate recep- tors have been shown not only to have neuroprotective effects but also to exhibit neurotoxic properties. In this study, we used c-Fos, a protein product of an immediate early gene, as a marker of neuronal injury to compare the neuroprotective effects of xenon and the neurotoxic properties of xenon, nitrous

D. Ma; S. Wilhelm; M. Maze; N. P. Franks

2002-01-01

19

Gas mixtures for spark gap closing switches  

DOEpatents

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.

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

1987-02-20

20

Drift velocity and gain in argon- and xenon-based mixtures  

E-print Network

We present measurements of drift velocities and gains in gas mixtures based on Ar and Xe, with CO2, CH4, and N2 as quenchers, and compare them with calculations. In particular, we show the dependence of Ar- and Xe-CO2 drift velocities and gains on the amount of nitrogen contamination in the gas, which in real experiments may build up through leaks. A quantification of the Penning mechanism which contributes to the Townsend coefficients of a given gas mixture is proposed.

Andronic, A; Braun-Munzinger, P; Garabatos, C; Tsiledakis, G

2004-01-01

21

Tunable V.U.V. radiation generated by non-resonant phase matched odd harmonic generation in xenon gas  

E-print Network

in xenon gas Tran ba' Chu (1,*), A. Bouvier (1), A. J. Bouvier (1) and R. Fischer (2) (1) Laboratoire de.U.V. radiation has been generated by non-resonant fifth-harmonic generation in xenon in the domain 1135-1170 Ã?) of the xenon gas is of the order of 10-47 e.s.u. J. Phys. France 49 (1988) 1725-1729 OCTOBRE 1988

Boyer, Edmond

22

Micromegas-TPC operation at high pressure in xenon-trimethylamine mixtures  

E-print Network

In this work we present a systematic study of Micromegas detectors in high pressure gaseous Xenon using trimethylamine (TMA) as quencher gas. Gas gains and energy resolutions for 22.1 keV X-rays are measured for pressures between 1 and 10 bar and various relative concentrations of TMA from 0.3 % to 15 %. We observe stable operation at all pressures, and a strongly enhanced gas gain, suggestive of Penning-like energy-transfer processes. The effect is present at all pressures and it is strongest at TMA concentrations ranging from 1.5 % to 3 %. Operating in this concentration range, the maximum gain reached values as high as x10^3 (x10^2) at 1 (10) bar. Besides, the energy resolution achievable for 22.1 keV X-rays is substantially better than the one previously obtained in pure Xe, going down to 7.3 % (9.6 %) FWHM for 1 (10) bar. These results are of interest for calorimetric applications of high pressure gas Xe TPCs, in particular for the search of the neutrinoless double beta decay of Xe-136. The resolutions achieved would extrapolate into 0.7 % (0.9 %) FWHM at the Qbb value of Xe-136 for 1 (10) bar.

S. Cebrián; T. Dafni; E. Ferrer-Ribas; I. Giomataris; D. Gonzalez-Diaz; H. Gómez; D. C. Herrera; F. J. Iguaz; I. G. Irastorza; G. Luzon; A. Rodríguez; L. Segui; A. Tomás

2012-11-23

23

Drift velocity and gain in argon- and xenon-based mixtures  

Microsoft Academic Search

We present measurements of drift velocities and gains in gas mixtures based on Ar and Xe, with CO2, CH4, and N2 as quenchers, and compare them with calculations. In particular, we show the dependence of Ar- and Xe–CO2 drift velocities and gains on the amount of nitrogen contamination in the gas, which in real experiments may build up through leaks.

A. Andronic; S. Biagi; P. Braun-Munzinger; C. Garabatos; G. Tsiledakis

2004-01-01

24

Krypton assay in xenon at the ppq level using a gas chromatographic system combined with a mass spectrometer  

E-print Network

We have developed a new method to measure krypton traces in xenon at so far unprecedented low concentrations. This is a mandatory task for many near-future low-background particle physics detectors. Our system is based on a cryogenic gas chromatographic krypton/xenon separation and a subsequent mass spectroscopic krypton quantification. We prove this system to reach a detection limit of 8 ppq (parts per quadrillion) and present results of distilled xenon with krypton concentrations below 1 ppt.

Lindemann, Sebastian

2014-01-01

25

Decompression in diving with gas mixtures (J. Riba) 1/22 Decompression in diving with gas mixtures  

E-print Network

Decompression in diving with gas mixtures (J. Riba) 1/22 Decompression in diving with gas mixtures;Decompression in diving with gas mixtures (J. Riba) 2/22 ÍNDICE Acronims..............................................................................5 2.2 Decompression mixtures

Riba Sagarra, Jaume

26

Gas phase pulse etching of silicon for MEMS with xenon difluoride  

Microsoft Academic Search

Xenon difluoride is an isotropic gas-phase etchant of silicon which has advantages in some aspects over anisotropic etchants such as KOH, EDP, and TMAH. An inexpensive, small, vacuum system is described for `pulse etching' single crystal silicon wafers (standard CMOS substrates) for releasing microelectromechanical systems (MEMS) devices. Results are presented of etching protocols from several silicon substrates which had been

I. W. T. Chan; K. B. Brown; R. P. W. Lawson; A. M. Robinson; Yuan Ma; D. Strembicke

1999-01-01

27

Separation of gas mixtures by centrifugation  

NASA Technical Reports Server (NTRS)

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.

Park, C.; Love, W. L.

1972-01-01

28

Transport coefficients of multicomponent gas mixtures  

Microsoft Academic Search

General expressions for the transport coefficients of multicomponent gas mixture have been written in a form where the computations for a given N-component gas mixture and for any order can be done on the computer without feeding the explicit expressions for the matrix elements. (General expressions, available in literature earlier, require seperate computer programs for each order of calculation.) These

Kuldip Singh; A. K. Dham; S. C. Gupta

1989-01-01

29

Ternary gas mixture for diffuse discharge switch  

DOEpatents

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.

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

1988-01-01

30

Evaluation of Xenon Gas Detection as a Means for Identifying Buried Transuranic Waste at the Radioactive Waste Management Complex, Idaho National Environmental and Engineering Laboratory  

Microsoft Academic Search

Xenon is produced as a fission product in nuclear reactors and through spontaneous fission of some transuranic (TRU) isotopes. Xenon gas is nearly inert and will be released from buried TRU waste. This document describes and evaluates the potential for analyzing xenon isotopes in soil gas to detect TRU waste in the subsurface at the Idaho National Environmental and Engineering

P Evan Dresel; Scott R. Waichler

2004-01-01

31

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

NASA Astrophysics Data System (ADS)

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.

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

32

PVT measurements for five natural gas mixtures  

E-print Network

Major Subject: Chemical Engineering PVT MEASUREMENTS FOR FIVE NATURAL GAS MIXTURES A Thesis by PHILIP PARAYIL SIMON Approved as to style and content by: James C. Holste (Chair of Committee) Kenneth N. Marsh (Member) Randolph C. Wilhoit (Member...) Raymond W. Flumerfelt (Head of Department) August 1991 ABSTRACT PVT Measurements for Five Natural Gas Mixtures (August 1991) Philip Parayil Simon, B. Tech. , Indian Institute of Technology, Madras Chair of Advisory Committee: Dr. James C. Holste...

Simon, Philip Parayil

1991-01-01

33

Searching for neutrinoless double beta decay with gas-xenon TPCs: R&D for next  

NASA Astrophysics Data System (ADS)

The search for neutrinoless double beta (??0?) decay is fundamental to probe the character of neutrinos and to determine the their mass. Several experiments in this field are using different techniques in order to achieve good energy resolution (? 1%), very low background contamination (˜ 10-4 counts/(keV.kg. y)) and large target mass (> 100 kg), that are required for that research. Natural xenon consists almost 9% of 136Xe, a possible ??0? emitter and can be easily enriched. A xenon TPC can provide the excellent energy resolution moreover, in a gaseous phase, the signature of the decay given by the two electrons can be detected reducing considerable the background. The NEXT collaboration aims to build a pressurized gaseous detector of about 100 kg of enriched xenon to be operated at the Canfranc Underground Laboratory in Spain. An extensive R&D has been carried out by the collaboration in the last two years with several prototypes, investigating both energy resolution and tracking capabilities in xenon gas.

Santorelli, Roberto; NEXT Collaboration

2012-09-01

34

Spatial characterization of extreme ultraviolet plasmas generated by laser excitation of xenon gas targets  

Microsoft Academic Search

At Laser-Laboratorium Göttingen laser-plasma sources were tested, which are going to be used for characterization of optical components and sensoric devices in the wavelength region from 11 to 13 nm. In all cases extreme ultraviolet (EUV) radiation is generated by focusing a Q-switched Nd:YAG laser into a pulsed gas puff target. By the use of xenon or oxygen as target

Sebastian Kranzusch; Christian Peth; Klaus Mann

2003-01-01

35

Gas mixtures for gas-filled radiation detectors  

DOEpatents

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.

Christophorou, Loucas G. (Oak Ridge, TN); McCorkle, Dennis L. (Knoxville, TN); Maxey, David V. (Knoxville, TN); Carter, James G. (Knoxville, TN)

1982-01-05

36

Gas mixtures for gas-filled particle detectors  

DOEpatents

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.

Christophorou, Loucas G. (Oak Ridge, TN); McCorkle, Dennis L. (Knoxville, TN); Maxey, David V. (Knoxville, TN); Carter, James G. (Oak Ridge, TN)

1980-01-01

37

Improved gas mixtures for gas-filled radiation detectors  

DOEpatents

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.

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

1980-03-28

38

Detection of Alpha Particles and Low Energy Gamma Rays by Thermo-Bonded Micromegas in Xenon Gas  

E-print Network

Micromegas is a type of micro-pattern gaseous detector currently under R&D for applications in rare event search experiments. Here we report the performance of a Micromegas structure constructed with a micromesh thermo-bonded to a readout plane, motivated by its potential application in two-phase xenon detectors for dark matter and neutrinoless double beta decay experiments. The study is carried out in pure xenon at room temperature. Measurements with alpha particles from the Americium-241 source showed that gas gains larger than 200 can be obtained at xenon pressure up to 3 atm. Gamma rays down to 8 keV were observed with such a device.

Yuehuan Wei; Liang Guan; Zhiyong Zhang; Qing Lin; Xiaolian Wang; Kaixuan Ni; Tianchi Zhao

2013-08-09

39

Luminescence evidence for bulk and surface excitons in free xenon clusters  

SciTech Connect

The cathodoluminescence spectra of free xenon clusters produced by condensation of xenon-argon gas mixtures in supersonic jets expanding into vacuum were studied. By varying the initial experimental parameters, including the xenon concentration, we could obtain clusters with a xenon core (300-3500 atoms) covered by an argon outer shell as well as shell-free xenon clusters ({approx_equal}1500 atoms). The cluster size and temperature ({approx_equal}40 K for both cases) were measured electronographically. Luminescence bands evidencing the existence of bulk and surface excitons were detected for shell-free xenon clusters. The emission from bulk excitons in small clusters is supposed to be due to processes of their multiple elastic reflections from the xenon-vacuum interface. The presence of an argon shell causes extinction of the excitonic bands. In addition, some bands were found which have no analogs for bulk xenon cryosamples.

Danylchenko, O. G.; Doronin, Yu. S.; Kovalenko, S. I.; Libin, M. Yu.; Samovarov, V. N.; Vakula, V. L. [B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Lenin Avenue, Kharkiv, 61103 (Ukraine)

2007-10-15

40

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

41

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

SciTech Connect

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.

Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

2014-01-29

42

Diffusion in mercury-argon gas mixtures  

NASA Astrophysics Data System (ADS)

Ab initio quantum-mechanical calculations of potential of interactions U( R) are performed for Hg-Ar. Using equations from the molecular kinetic theory of rarefied gases, a new statistical correlation is found between data on the potential of interaction (molecular beams, molecular spectroscopy, and potential U( R)) and experimental data on the mutual diffusion coefficient (MDC) of mercury-argon gas mixtures. Calculated reference data on the MDC of mercury-argon gas mixtures in the temperature range of 300 to 600 K are offered as a possible standard for calibrating instruments that measure MDCs of liquid vapors and inert gases using the Stefan method.

Meshkov, V. V.; Popov, V. N.; Fokin, L. R.

2014-04-01

43

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

SciTech Connect

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.

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

2009-01-01

44

NEXT: Searching for the neutrinoless double beta decay with a gas-xenon TPC  

NASA Astrophysics Data System (ADS)

Although different techniques are used to search for the neutrinoless double beta decay, the common challenges for all the existing or planned experiments are to achieve a good energy resolution and large background rejection factors. The NEXT collaboration addresses these two challenges with a high-pressure gas-Xenon TPC. Natural Xenon consists of almost 9% of 136Xe, a ??0? candidate emitter, and can be easily enriched. When used as a calorimeter, 136Xe yields an excellent energy resolution. This fact, combined with the expected long life of the ??2? mode, accounts for negligible intrinsic backgrounds up to masses of 1 ton. Furthermore, external backgrounds can be rejected with high efficiency by means of the electron tracking capabilities of the TPC. A detector containing about 100 kg of enriched Xenon is expected to be installed at Canfranc Underground Laboratory (LSC) within the next 5 years, with the twofold aim of exploring the degenerated hierarchy of the neutrino mass and providing deep understanding of the experimental techniques which allow extrapolation to larger detectors.

Novella, P.; NEXT Collaboration

2010-01-01

45

Primary and secondary scintillation measurements in a xenon Gas Proportional Scintillation Counter  

E-print Network

NEXT is a new experiment to search for neutrinoless double beta decay using a 100 kg radio-pure high-pressure gaseous xenon TPC. The detector requires excellent energy resolution, which can be achieved in a Xe TPC with electroluminescence readout. Hamamatsu R8520-06SEL photomultipliers are good candidates for the scintillation readout. The performance of this photomultiplier, used as VUV photosensor in a gas proportional scintillation counter, was investigated. Initial results for the detection of primary and secondary scintillation produced as a result of the interaction of 5.9 keV X-rays in gaseous xenon, at room temperature and at pressures up to 3 bar, are presented. An energy resolution of 8.0% was obtained for secondary scintillation produced by 5.9 keV X-rays. No significant variation of the primary scintillation was observed for different pressures (1, 2 and 3 bar) and for electric fields up to 0.8 V cm-1 torr-1 in the drift region, demonstrating negligible recombination luminescence. A primary scintillation yield of 81 \\pm 7 photons was obtained for 5.9 keV X-rays, corresponding to a mean energy of 72 \\pm 6 eV to produce a primary scintillation photon in xenon.

L. M. P. Fernandes; E. D. C. Freitas; M. Ball; J. J. Gómez-Cadenas; C. M. B. Monteiro; N. Yahlali; D. Nygren; J. M. F. dos Santos

2010-09-15

46

Structural plasticity of the phage P22 tail needle gp26 probed with xenon gas.  

PubMed

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. PMID:19241380

Olia, Adam S; Casjens, Sherwood; Cingolani, Gino

2009-03-01

47

Structural plasticity of the phage P22 tail needle gp26 probed with xenon gas  

PubMed Central

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 Å 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 ?-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. PMID:19241380

Olia, Adam S; Casjens, Sherwood; Cingolani, Gino

2009-01-01

48

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

E-print Network

We report on results obtained with the NEXT-DEMO prototype of the NEXT-100 high-pressure xenon gas time projection chamber (TPC), 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 coeffcients 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 $0.561\\pm 0.045$, translating into an average energy to produce a primary scintillation photon of $W_{\\rm ex}=(39.2\\pm 3.2)$ eV.

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

2015-02-03

49

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

NASA Astrophysics Data System (ADS)

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 ?-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.

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

50

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

E-print Network

We report on results obtained with the NEXT-DEMO prototype of the NEXT-100 high-pressure xenon gas time projection chamber (TPC), 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 coeffcients 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 $0.561\\pm 0.045$, translating into an average energy to produce a primary s...

Serra, L; 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; Morata, J A Hernando; 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; Vidal, J Muñoz; Nebot-Guinot, M; Nygren, D; Oliveira, C A B; Pérez, J; Aparicio, J L Pérez; Querol, M; Renner, J; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, F P; Santos, J M F dos; 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

2014-01-01

51

NEXT: Neutrino Experiment with high pressure Xenon gas TPC  

NASA Astrophysics Data System (ADS)

The search of the neutrinoless double- ? decay address the major Physics goals of revealing the nature of the neutrino and setting an absolute scale for its mass. The observation of a positive ??0? signal, the unique signature of Majorana neutrinos, would have deep consequences in particle physics and cosmology. Therefore, any claim of observing a positive signal shall require extremely robust evidences. NEXT is a new double- ? experiment which aims at building a 100 kg high pressure Xe136 gas TPC, to be hosted in the Canfranc Underground Laboratory (LSC), in Spain. This paper address the novel design concept of NEXT TPC believed to provide a pathway for an optimized and robust double- ? experiment.

Yahlali, Nadia; Ball, M.; Cárcel, S.; Díaz, J.; Gil, A.; Gómez Cadenas, J. J.; Martín-Albo, J.; Monrabal, F.; Serra, L.; Sorel, M.

2010-05-01

52

The Narrow Pulse Approximation and Long Length Scale Determination in Xenon Gas Diffusion NMR Studies of Model Porous Media  

Microsoft Academic Search

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

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

2002-01-01

53

Dark Matter Directionality Revisited with a High Pressure Xenon Gas Detector  

E-print Network

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 ...

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

2015-01-01

54

Shear viscosity of hadronic gas mixtures  

E-print Network

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

K. Itakura; O. Morimatsu; H. Otomo

2008-05-12

55

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

E-print Network

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

Lorca, D; Monrabal, F

2012-01-01

56

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

E-print Network

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

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

2012-10-15

57

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

58

IGNITION IMPROVEMENT OF LEAN NATURAL GAS MIXTURES  

SciTech Connect

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.

Jason M. Keith

2005-02-01

59

NEXT, high-pressure xenon gas experiments for ultimate sensitivity to Majorana neutrinos  

E-print Network

In this paper we describe an innovative type of Time Projection Chamber (TPC), which uses high-pressure xenon gas (HPXe) and electroluminescence amplification of the ionization charge as the basis of a apparatus capable of fully reconstructing the energy and topological signal of rare events. We will discuss a specific design of such HPXe TPC, the NEXT-100 detector, that will search for neutrinoless double beta decay using 100-150 kg of xenon enriched in the isotope Xe-136. NEXT-100 is currently under construction, after completion of an accelerated and very successful R&D period. It will be installed at the Laboratorio Subterr\\'aneo de Canfranc (LSC), in Spain. The commissioning run is expected for late 2013 or early 2014. We will also present physics arguments that suggest that the HPXe technology can be extrapolated to the next-to-next generation (e.g, a fiducial mass of 1 ton of target), which will fully explore the Majorana nature of the neutrino if the mass hierarchy is inverse.

Gomez-Cadenas, J J; Monrabal, F

2012-01-01

60

NEXT, high-pressure xenon gas experiments for ultimate sensitivity to Majorana neutrinos  

E-print Network

In this paper we describe an innovative type of Time Projection Chamber (TPC), which uses high-pressure xenon gas (HPXe) and electroluminescence amplification of the ionization charge as the basis of an apparatus capable of fully reconstructing the energy and topological signature of rare events. We will discuss a specific design of such HPXe TPC, the NEXT-100 detector, that will search for neutrinoless double beta decay events using 100-150 kg of xenon enriched in the isotope Xe-136. NEXT-100 is currently under construction, after completion of an accelerated and very successful R&D period. It will be installed at the Laboratorio Subterr\\'aneo de Canfranc (LSC), in Spain. The commissioning run is expected for late 2013 or early 2014. We will also present physics arguments that suggest that the HPXe technology can be extrapolated to the next-to-next generation (e.g, a fiducial mass of 1 ton of target), which will fully explore the Majorana nature of the neutrino if the mass hierarchy is inverse.

J. J. Gómez-Cadenas; J. Martín-Albo; F. Monrabal; for the NEXT Collaboration

2012-11-21

61

NEXT, high-pressure xenon gas experiments for ultimate sensitivity to Majorana neutrinos  

NASA Astrophysics Data System (ADS)

In this paper we describe an innovative type of Time Projection Chamber (TPC), which uses high-pressure xenon gas (HPXe) and electroluminescence amplification of the ionization charge as the basis of an apparatus capable of fully reconstructing the energy and topological signature of rare events. We will discuss a specific design of such HPXe TPC, the NEXT-100 detector, that will search for ??0? events using 100-150 kg of xenon enriched in the isotope 136Xe. NEXT-100 is currently under construction, after completion of an accelerated and very successful R&D period. It will be installed at the Laboratorio Subterr&aposaneo de Canfranc (LSC), in Spain. The commissioning run is expected for late 2013 or early 2014. We will also present physics arguments that suggest that the HPXe technology can be extrapolated to the next-to-next generation (e.g, a fiducial mass of 1 ton of target), which will fully explore the Majorana nature of the neutrino if the mass hierarchy is inverse.

Gómez-Cadenas, J. J.; Martín-Albo, J.; Monrabal, F.

2012-11-01

62

An automated multidimensional preparative gas chromatographic system for isolation and enrichment of trace amounts of xenon from ambient air.  

PubMed

The monitoring of radioactive xenon isotopes is one of the principal methods for the detection of nuclear explosions in order to identify clandestine nuclear testing. In this work, a miniaturized, multiple-oven, six-column, preparative gas chromatograph was constructed in order to isolate trace quantities of radioactive xenon isotopes from ambient air, utilizing nitrogen as the carrier gas. The multidimensional chromatograph comprised preparative stainless steel columns packed with molecular sieves, activated carbon, and synthetic carbon adsorbents (e.g., Anasorb®-747 and Carbosphere®). A combination of purification techniques--ambient adsorption, thermal desorption, back-flushing, thermal focusing, and heart cutting--was selectively optimized to produce a well-defined xenon peak that facilitated reproducible heart cutting and accurate quantification. The chromatographic purification of a sample requires approximately 4 h and provides complete separation of xenon from potentially interfering components (such as water vapor, methane, carbon dioxide, and radon) with recovery and accuracy close to 100%. The preparative enrichment process isolates and concentrates a highly purified xenon gas fraction that is suitable for subsequent ultra-low-level ?-, ß/?-spectroscopic or high-resolution mass spectrometric measurement (e.g., to monitor the gaseous fission products of nuclear explosions at remote locations). The Xenon Processing Unit is a free-standing, relatively lightweight, and transportable system that can be interfaced to a variety of sampling and detection systems. It has a relatively inexpensive, rugged, and compact modular (19-inch rack) design that provides easy access to all parts for maintenance and has a low power requirement. PMID:21347675

Larson, Tuula; Östman, Conny; Colmsjö, Anders

2011-04-01

63

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

PubMed

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

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

2015-01-01

64

HDT mixtures treatment strategies by gas chromatography  

SciTech Connect

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)

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

2008-07-15

65

Is xenon eldest?  

NASA Technical Reports Server (NTRS)

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.

Zahnle, K.

1994-01-01

66

Dark Matter Directionality Revisited with a High Pressure Xenon Gas Detector  

E-print Network

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 or one between 200 GeV and 400 GeV. For an intermediate mass range, we find it challenging to observe anisotropy of dark matter distribution.

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

2015-03-13

67

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

PubMed Central

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

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

2011-01-01

68

Investigation of the combined adsorption of krypton, xenon, and water vapor of the off-gas of atomic power stations  

Microsoft Academic Search

A radiochromatogra phic system of purifying the off-gas from the short-lived krypton, xenon, and iodine nuclides is presently used in Russian atomic power stations and in foreign atomic power stations equipped with the aid of the USSR. The basic elements of the system are filter-adsorbers filled with activated carbon and a drying unit [1-3]. Dynamic adsorption and radioactive decay in

I. E. Nakhutin; D. V. Ochkin; S. A. Tret'yak

1980-01-01

69

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

SciTech Connect

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.

Hunter, D.

2009-03-16

70

Flammability of gas mixtures containing volatile organic compounds and hydrogen  

Microsoft Academic Search

An experimental program was conducted to evaluate the accuracy of some current methods for predicting the flammability of gas mixtures containing hydrogen and flammable or nonflammable volatile organic compounds (VOCs) in air. The specific VOCs tested were toluene, 1,2-dichloroethane, 2-butanone, and carbon tetrachloride. The lower flammability limits (LFLs) of gas mixtures containing equal molar quantities of the components were determined

Kevin J. Liekhus; Isaac A. Zlochower; Kenneth L. Cashdollar; Sinisa M. Djordjevic; Cindy A. Loehr

2000-01-01

71

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

NASA Technical Reports Server (NTRS)

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).

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

2002-01-01

72

Optical imaging capillary gas proportional counter with Penning mixtures  

Microsoft Academic Search

An optical imaging gas proportional counter with a capillary plate has been tested using a gas mixture of Ar+8%CH4+2%TMA.. Both charge and light signals were investigated. The gas gain was found to be approximately 70 times greater than that previously obtained in Ar+10%CH 4 and the new mixture operates at a gap voltage 220 V lower than the Ar+10%CH4, indicating

T. Masuda; H. Sakurai; Y. Inoue; S. Gunji; K. Asamura

2002-01-01

73

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

74

New approach in direct-simulation of gas mixtures  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

75

Xenon forms stable compound with fluorine  

NASA Technical Reports Server (NTRS)

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.

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

1966-01-01

76

A novel $^{83\\mathrm{m}}$Kr tracer method for characterizing xenon gas and cryogenic distillation systems  

E-print Network

The radioactive isomer $^{83\\mathrm{m}}$Kr 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 $\\gamma$-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 $^{83}$Kr, one does not risk contamination of any low-background experiment with long- lived radionuclides. In this paper, we present two new applications of $^{83\\mathrm{m}}$Kr. It can be used as a radioactive tracer in noble gases to characterize the particle flow inside of gas routing systems. A method of doping $^{83\\mathrm{m}}$Kr into xenon gas and its detection, using special custom-made detectors, based on a photomultiplier tube, is described. This technique has been used to determine the circulation speed of gas particles inside of a gas purification system for xenon. Furthermore, 83m Kr can be used to...

Rosendahl, S; Brown, E; Cristescu, I; Fieguth, A; Huhmann, C; Lebeda, O; Levy, C; Murra, M; Schneider, S; Vénos, D; Weinheimer, C

2014-01-01

77

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

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.

2001-01-01

78

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

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.

2001-01-01

79

Degenerate atom-molecule mixture in a cold Fermi gas  

SciTech Connect

We show that the atom-molecule mixture formed in a degenerate atomic Fermi gas with interspecies repulsion near a Feshbach resonance constitutes a peculiar system where the atomic component is almost nondegenerate but quantum degeneracy of molecules is important. We develop a thermodynamic approach for studying this mixture, explain experimental observations, and predict optimal conditions for achieving molecular Bose-Einstein condensation.

Kokkelmans, S.J.J.M.F.; Salomon, C. [Laboratoire Kastler Brossel, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris 05 (France); Shlyapnikov, G.V. [Laboratoire Kastler Brossel, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris 05 (France); FOM Institute AMOLF, Kruislaan 407, 1098 SJ Amsterdam (Netherlands); Russian Research Center Kurchatov Institute, Kurchatov Square, 123182 Moscow (Russian Federation)

2004-03-01

80

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

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.

2001-01-01

81

Antiapoptotic activity of argon and xenon.  

PubMed

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

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

2013-08-15

82

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

NASA Astrophysics Data System (ADS)

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.

Nygren, David

2013-04-01

83

Composition for absorbing hydrogen from gas mixtures  

DOEpatents

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.

Heung, Leung K. (Aiken, SC); Wicks, George G. (Aiken, SC); Lee, Myung W. (Aiken, SC)

1999-01-01

84

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

PubMed Central

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

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

85

In situ measurements of Krypton in Xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed  

E-print Network

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 $330 \\pm 200$ ppt.

Brown, Ethan; Huhmann, Christian; Weinheimer, Christian; Kettling, Hans

2012-01-01

86

In situ measurements of Krypton in Xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed  

E-print Network

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 $330 \\pm 200$ ppt.

Ethan Brown; Stephan Rosendahl; Christian Huhmann; Christian Weinheimer; Hans Kettling

2012-12-20

87

Method of separating isotopes from a gas mixture  

Microsoft Academic Search

The invention relates to a method of separating isotopes from a gas mixture, of once ionized uranium the isotopes being separated by the combined effect of photon irradiation by laser light followed by penning ionization of ions selectively excited by the laser light. According to the invention a gas of once ionized uranium isotopes is irradiated with laser light made

J. Chatelet; M. Clerc; A. Coste; P. Rigny

1983-01-01

88

Reduced viscosity interpreted for fluid/gas mixtures  

NASA Technical Reports Server (NTRS)

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.

Lewis, D. H.

1981-01-01

89

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

SciTech Connect

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.

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

2013-09-01

90

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

SciTech Connect

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)

Garn, T.G.; Greenhalgh, M.R.; Law, J.D. [Idaho National Laboratory, 1625 N. Fremont Ave., Idaho Falls, ID 83415 (United States)

2013-07-01

91

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

SciTech Connect

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.

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

2013-10-01

92

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

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.

2001-01-01

93

New RPC gas mixtures for large area apparatuses  

NASA Astrophysics Data System (ADS)

The working gas choise has always been a crucial topic for RPC. The optimization of the gas mixture, for different purposes, allowed the RPC detector to be successful in many experiments of today physics [1,2]. Both running and future experiments however could profit from new gases with low environmental impact, low cost and good behavior with respect to ageing and RPC performances. We present here the first results in the search for this new gas.

Cardarelli, R.; Di Stante, L.; Liberti, B.; Paolozzi, L.; Pastori, E.; Santonico, R.

2014-11-01

94

High severity pyrolysis of shale and petroleum gas oil mixtures  

Microsoft Academic Search

Light gas oil and heavy gas oil from Paraho shale oil and their mixtures with a petroleum light gas oil were pyrolyzed in the presence of steam at 880-900°C and contact times between 60 and 90 ms in a nonisothermal bench-scale pyrolysis reactor. Blending of petroleum LGO into the shale oil feeds provided product yields that were the weighted linear

Harry P. Leftin; David S. Newsome

1986-01-01

95

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

PubMed Central

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

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

96

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

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

97

Lattice Boltzmann model for thermal binary-mixture gas flows.  

PubMed

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

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

2013-05-01

98

Gas sampling system for reactive gas-solid mixtures  

DOEpatents

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.

Daum, Edward D. (Alliance, OH); Downs, William (Alliance, OH); Jankura, Bryan J. (Mogadore, OH); McCoury, Jr., John M. (Mineral City, OH)

1989-01-01

99

Gas sampling system for reactive gas-solid mixtures  

DOEpatents

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.

Daum, Edward D. (Alliance, OH); Downs, William (Alliance, OH); Jankura, Bryan J. (Mogadore, OH); McCoury, Jr., John M. (Mineral City, OH)

1990-01-01

100

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

NSDL National Science Digital Library

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

Dr. Charles Ward

101

Acoustics and precondensation phenomena in gas-vapor saturated mixtures  

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

102

Current pulses in dc glow discharges in electronegative gas mixtures  

Microsoft Academic Search

Regular oscillations in the current are predicted in low-pressure, planar discharges under certain conditions in electronegative gas mixtures in which the attachment rate coefficient is large at low values of E\\/P, the ratio of the electric-field strength to the gas pressure. The frequency of the oscillations is about 10 kHz, and depending on the conditions of pressure, gap spacing, and

L. C. Pitchford

1995-01-01

103

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

104

Internal combustion engines fueled by natural gas—hydrogen mixtures  

Microsoft Academic Search

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

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

2004-01-01

105

Optical spectra of binary rare-gas mixtures  

Microsoft Academic Search

The results of experimental and theoretical investigations of the properties of heteronuclear rare-gas dimers are presented. Spectra in the vacuum ultraviolet region received primary emphasis. It is shown that the bulk of the excitation energy stored by the low-temperature plasma of binary mixtures is released by the heteronuclear dimers in a narrow spectral band near atomic resonance lines.

Gennadii N Gerasimov

2004-01-01

106

Dissociation of a Product of a Surface Reaction in the Gas Phase: Xenon Difluoride Reaction with Si  

NASA Astrophysics Data System (ADS)

Xenon difluoride interacts with Si(100)2x1 at the dangling bond sites by atom abstraction whereby a dangling bond abstracts a F atom from XeF2, forming a Si-F bond and scattering the complementary XeF radical. The XeF fragment produced by this reaction follows either of two subsequent pathways. In one pathway, it interacts with the surface a second time, undergoing a second F atom abstraction reaction and giving rise to a second Si-F bond and a scattered Xe atom. In the other pathway, it scatters into the gas phase. Some of the XeF scattered into the gas phase is observed to dissociate. The dissociation arises from the partitioning of sufficient reaction exothermicity to the rovibrational continuum of the ground electronic state of XeF. The resulting F and Xe atoms are shown conclusively to arise from dissociation of gas phase XeF by demonstrating that the angle-resolved velocity distributions of F, Xe, and XeF conserve momentum, energy, and mass. The dissociation occurs when XeF is about 2 Å away from the surface. The XeF bond orientations at the time of dissociation are largely those where the F atom of the XeF fragment is pointing into the vacuum. This experiment documents the first observation of dissociation of a product of a surface reaction in the gas phase.

Ceyer, S. T.

2004-03-01

107

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

Microsoft Academic Search

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

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

1995-01-01

108

Plasmas Generated With Gas Mixtures at the Atmospheric Pressure  

NASA Astrophysics Data System (ADS)

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.

Calzada, M. D.; Muñoz, J.; Rincón, R.; Jiménez, M.; Sáez, M.

109

A non-invasive ultrasonic gas sensor for binary gas mixtures  

Microsoft Academic Search

A non-invasive gas sensor has been fabricated for quantitative measurement of a specific gas in a binary mixture such as H2, He, etc. mixed in air, based on time of flight (TOF) measurements of the ultrasonic signal. A test gas with different concentration was mixed in air and its concentration was determined using the observed TOF data and a theoretically

J. C. Vyas; V. R. Katti; S. K. Gupta; J. V. Yakhmi

2006-01-01

110

Perturbation viscometry of gas mixtures: fitting a model to logarithmic viscosity gradients  

Microsoft Academic Search

Perturbation viscometry is a recently developed method which measures the logarithmic gradient of the viscosity–composition curve for gas mixtures using a variant of capillary-tube viscometry. A gas mixture flowing through a capillary has its composition perturbed by the addition of a small flow of gas, normally one of the pure components of the gas mixture. Two pressure changes, the first

B. A. Buffham; G. Mason; M. J. Heslop; P. A. Russell

2002-01-01

111

The prediction of the viscosity of dense gas mixtures  

SciTech Connect

An extension of an earlier procedure for the evaluation of the viscosity of very dense gas mixtures is proposed. The scheme is based upon the rigid-sphere theory of dense fluids, which is modified to take into account the behavior of real gases in a self-consistent manner. In particular, it is shown that a pseudoradial distribution function for each pure gas constructed from pure component viscosity data is a smooth function of density and is well behaved in limits of both high and low density. The method proposed removes the restriction on the range of applicability of earlier methods. Comparisons with the limited amount of experimental information available indicate that the procedure allows evaluation of the viscosity of gas mixtures to within a few percent.

Vesovic, V.; Wakeham, W.A.

1989-01-01

112

Electrochemical separation and concentration of hydrogen sulfide from gas mixtures  

DOEpatents

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.

Winnick, Jack (Atlanta, GA); Sather, Norman F. (Naperville, IL); Huang, Hann S. (Darian, IL)

1984-10-30

113

A Decade of Xenon Chemistry  

ERIC Educational Resources Information Center

Presents reactions for the formation of xenon compounds and compounds of the other inert gases. Provides bonding and structure theories for noble gas compounds and speculates on possible applications. (GS)

Moody, G. J.

1974-01-01

114

Optical pumping and xenon NMR  

SciTech Connect

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.

Raftery, M.D.

1991-11-01

115

Optical pumping and xenon NMR  

SciTech Connect

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.

Raftery, M.D.

1991-11-01

116

Critical Viscosity of Xenon  

NASA Technical Reports Server (NTRS)

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.

2001-01-01

117

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

SciTech Connect

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.

Gulati, P., E-mail: pgulati1512@gmail.com [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan-333031 (India); Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022 (India); Prakash, R.; Pal, U. N.; Kumar, M. [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan-333031 (India); Vyas, V. [Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022 (India)

2014-07-07

118

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

Microsoft Academic Search

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

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

1998-01-01

119

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

Code of Federal Regulations, 2013 CFR

...Solar mixtures. OFE will grant a permanent mixtures exemption for the use of a 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...

2013-01-01

120

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

DOEpatents

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.

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

2011-01-04

121

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

122

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

E-print Network

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

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

2002-11-10

123

Plasma polymerization of an ethylene-nitrogen gas mixture  

NASA Technical Reports Server (NTRS)

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.

Hudis, M.; Wydeven, T.

1975-01-01

124

Lorentz Angle Measurement for CO2/Isobutane Gas Mixtures  

E-print Network

We have developed a Lorentz angle measurement system for cool gas mixtures in the course of our R&D for a proposed JLC central drift chamber (JLC-CDC). The measurement system is characterized by the use of two laser beams to produce primary electrons and flash ADCs to read their signals simultaneously. With this new system, we have measured Lorentz angles for CO2/isobutane gas mixtures with different proportions (95:5, 90:10, and 85:15), varying drift field from 0.6 to 2.0 kV/cm and magnetic field up to 1.5 T. The results of the measurement are in good agreement with GARFIELD/MAGBOLTZ simulations.

Hoshina, K; Khalatyan, N S; Nitoh, O; Okuno, H; Kato, Y; Kobayashi, M; Kurihara, Y; Kuroiwa, H; Nakamura, Y; Sakieda, K; Suzuki, Y; Watanabe, T

2002-01-01

125

Modeling Expansions of Nitrogen-Xe Gas Mixtures  

NASA Astrophysics Data System (ADS)

Existing experiments using orifice expansions of gas mixtures provide evidence of collisional alignment of the rotor spin vectors. Expansion flow of N2 - Xe gas mixtures is modeled on the basis of kinetic equations, extending the previously developed interlaced system and the model for N2. Numerical results of rotational relaxation are in qualitative agreement with what is known from experiments in pure N2, and velocity slip is in good agreement with existing experiments. Some first results on alignment, defined as the ratio nn/np (with n as number density, and index n=spin vector normal to flow direction, p= parallel), indicate that this ratio first grows with p0D, then decays again, and that a large number of collisions is required to build the alignment.

Beylich, Alfred E.

2003-05-01

126

Gettering of hydrogen and methane from a helium gas mixture  

SciTech Connect

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.

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

2014-11-01

127

Using gas-solid mixture conservation laws for volcanic eruptions  

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

128

A new organosilicon adsorbent for air-gas mixture purification  

Microsoft Academic Search

Natural zeolites (klinoptiolits) were treated with Onkosorb adsorbent (N,N?-bis(3-triethoxysilyl-propyl-thiocarbamide)) to\\u000a attain greater nitrosamine (NA) and polycyclic aromatic hydrocarbon (PAH) adsorption capacity. The efficiency of volatile\\u000a NA recovery rose from 30 to 77%; that of PAH recovery, from 20 to 63.7 %. The increased adsorption efficiency of the toxicants\\u000a from an air-gas mixture was also reflected in biological indicators. Prolonged exposure

I. V. Zhigacheva; L. S. Evseenko; E. B. Burlakova; M. G. Voronkov; L. V. Krivosheeva

2011-01-01

129

Predicting detection probabilities for gas mixtures over HSI backgrounds  

SciTech Connect

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.

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

2009-12-29

130

Experimental study of gas mixtures in strong non-uniform electric fields  

Microsoft Academic Search

Argon-based gas mixtures of various concentration ratios at low pressures were studied in a gas proportional counter. Over-exponential increase of gas gain in mixtures with low partial pressure of any admixture was observed. The best energy resolution was measured at a gas gain of several hundreds for lower admixture concentrations, but at high gas gains R degraded very fast. The

I. Krajcar Broni?; B. Grosswendt

2001-01-01

131

Predicting flammability of gas mixtures containing volatile organic compounds  

SciTech Connect

One requirement regarding the transportation of transuranic (TRU) radioactive waste containers currently limits the total concentration of potentially flammable volatile organic compounds (VOCs) and flammable gases in the headspace of the waste container. Typical VOCs observed in the drums include aromatic hydrocarbons, ketones, alcohols, cyclohexane, as well as chlorinated hydrocarbons (alkanes and alkenes). Flammable gases, such as hydrogen and methane, may be generated in the containers by radiation-induced decomposition (radiolysis) of water and hydrocarbon waste forms. An experimental program was initiated to identify an accurate means for predicting flammability for gas mixtures containing one or more of the following species: hydrogen, carbon tetrachloride, 1,2-dichloroethane, toluene, or 2-butanone. The lower flammability limits (LFL) of gas mixtures containing equimolar quantity for each species were determined in a 19-liter laboratory flammability chamber using a strong spark ignition source. The group factor contribution method was determined to be more accurate than the LeChatelier method for estimating the LFL for these gas mixtures.

Liekhus, K. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Zlochower, I. [National Inst. for Occupational Safety and Health, Pittsburgh, PA (United States). Pittsburgh Research Lab.; Djordjevic, S.; Loehr, C. [Benchmark Environmental, Albuquerque, NM (United States)

1997-12-31

132

Critical Viscosity of Xenon investigators  

NASA Technical Reports Server (NTRS)

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.

2001-01-01

133

HERA-B Gas Systems The gas mixture, the gas volume of the corresponding detector and the required gas flow are given. All detectors are operating at nominal  

E-print Network

HERA-B Gas Systems The gas mixture, the gas volume of the corresponding detector and the required 50 purif. chain 93% Ar + 7% H2 0,5 bottle at 3rd floor Transition Radiation TRD chamber gas 70% Xe 6 8 Nitrogen N2 flushing gas 100% N2 - 50 - 21 50 Argon Ar flushing gas 100% Ar - 10 - 15 21 Helium

134

Gas amplification and ionization coefficients in isobutane and argon–isobutane mixtures at low gas pressures  

Microsoft Academic Search

Measurements of the mean gas amplification factor in isobutane and in argon–isobutane mixtures are performed at total gas pressures of 10, 20, 30, 60 and 90 kPa over a range of reduced electric field strength 5×104gas gain with applied high voltage are observed. The

Ines Krajcar Broni?; Bernd Grosswendt

1998-01-01

135

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

DOEpatents

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.

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

1990-01-01

136

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

DOEpatents

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.

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

2013-01-29

137

METEORITIC KRYPTON AND BARIUM VERSUS THE GENERAL ISOTOPIC ANOMALIES IN METEORITIC XENON  

Microsoft Academic Search

General isotopic anomalies in meteoritic xenon are described in detail. ; Where superior isotopic analyses exist, the xenon anomalies appear to be the same ; for all meteorites. In other cases there is fair evidence that the xenon ; examined is a mixture of meteoritic and contaminating atmospheric xenon. Two ; superior krypton analyses for carbonaceous chondrites show no anomalies

D. Krummenacher; C. M. Merrihue; R. O. Pepin; J. H. Reynolds

1962-01-01

138

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

PubMed Central

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

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

2014-01-01

139

Current pulses in dc glow discharges in electronegative gas mixtures  

NASA Astrophysics Data System (ADS)

Regular oscillations in the current are predicted in low-pressure, planar discharges under certain conditions in electronegative gas mixtures in which the attachment rate coefficient is large at low values of E/P, the ratio of the electric-field strength to the gas pressure. The frequency of the oscillations is about 10 kHz, and depending on the conditions of pressure, gap spacing, and applied voltage, the current wave form varies from a near-sinusoidal shape to regularly repeating and well-separated spikes with a peak current density on the order of or less than 1 mA/cm2. The instability which gives rise to these oscillations is due to attachment, and the oscillations result from alternate phases of space charge buildup and decay. Thus, the current oscillations predicted here in planar discharges are analogous to Trichel pulses, periodic current spikes which are observed in negative point-plane corona discharges in electronegative gases.

Pérès, Irène; Pitchford, L. C.

1995-07-01

140

Transport phenomena in a reactive quaternary gas mixture  

NASA Astrophysics Data System (ADS)

Quaternary gas mixtures which undergo a binary and reversible chemical reaction of the type A+B?C+D are analyzed within the framework of Boltzmann equation in order to investigate the effects caused by the reactions on the transport coefficients. The gas system is considered close to chemical equilibrium, a state in which the affinity has a small value characterizing the final stage of a chemical reaction. This kind of the reaction is also known in the literature as fast processes, i.e., processes whose frequencies of the interactions due to chemical reactions is of the same order of the elastic interactions between the constituents of the system. The theory is applied for two known reactions: H2+Cl?HCl+H and H+D2?HD+D. The coefficients of reaction rate, shear viscosity, thermal conductivity, diffusion and thermal diffusion ratio are analyzed for both reactions by considering the different parameters which characterize these chemical reactions.

Silva, Adriano W.; Alves, Giselle M.; Kremer, Gilberto M.

2007-02-01

141

Two fluid gas and dust mixtures in SPH  

NASA Astrophysics Data System (ADS)

One of the most challenging aspects of numerical simula3ons of dust and gas mixtures is the o6en enormous difference between gas and dust evolu3onary 3me scales. Whenever the dust stopping 3me becomes much smaller than the gas evolu3onary 3me scale, explicit/ implicit integra3on schemes require an excessively large number of 3me-steps, and none of the previous SPH schemes in the two fluid approach (Monaghan & Kocharyan 1995 and 1997; Maddison, Humble & Murray 2003; Rice et al. 2004; Barriere-Fouchet et al. 2005, Laibe & Price 2012) have addressed this problem. In the present work, a method to avoid the 3me integra3on of the small dusty grains evolu3on equa3ons, in the Smoothed Par3cle Hydrodynamics (SPH) two fluid approach is proposed. By assuming a very simple exponen3al decay model for the rela3ve velocity between the gas and dust components, all the effec3ve characteris3cs of the drag force can be reproduced. Taking as a reference the recent work of Laibe & Price (2011/12) a series of tests have been performed in order to compare the accuracy of the present method with a standard integra3on method.

Loren-Aguilar, Pablo; Bate, Matthew R.

2013-07-01

142

Xenon Additives Detection in Helium Micro-Plasma Gas Analytical Sensor  

NASA Astrophysics Data System (ADS)

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.

Tsyganov, Alexander; Kudryavtsev, Anatoliy; Mustafaev, Alexander

2012-10-01

143

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

Code of Federal Regulations, 2010 CFR

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

2010-01-01

144

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

Code of Federal Regulations, 2012 CFR

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

2012-01-01

145

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

Code of Federal Regulations, 2011 CFR

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

2011-01-01

146

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

E-print Network

sample were collected and compared to HydraFLASH® predictions. Different percentages of 2-hydroxy-N,N,N-trimethylethanaminium chloride, also known as choline chloride ionic liquid, were used as hydrate inhibitor for the same gas mixture. The ionic liquid’s...

Othman, Enas Azhar

2014-04-07

147

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

DOEpatents

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.

Mirzadeh, Saed (East Setauket, NY); Lambrecht, Richard M. (Quogue, NY)

1987-01-01

148

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

SciTech Connect

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.

McKinsey, Daniel Nicholas [Yale University] [Yale University

2013-08-27

149

Magnetic resonance imaging of convection in laser-polarized xenon  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

150

Simulation of Gas Mixtures in RF Discharges for Nitride Deposition  

NASA Technical Reports Server (NTRS)

Tungsten and titanium nitride films have long been grown by chemical vapor deposition (CVD) methods. However, there has been recent interest in low temperature growth using plasma enhanced CVD. For the present work, we focus on the radio frequency (BE) discharge characteristics of gas mixtures used in nitride deposition (for example, WF6 and ammonia). Because the radial variations for a standard 200 mm, parallel plate reactor are limited to a small zone near the edges of the electrodes, a 1-D (one-dimensional) analysis is considered. This model consists of a self-consistent, 3-D (three-dimensional) moment fluid simulation that solves the continuity, momentum, and energy equations for neutral and charged species. The results in terms of plasma structure, radical concentrations, and local deposition rate will be presented. We will also compare the 1-D results with those obtained from a 2-D hybrid plasma equipment model (HPEM) developed at the University of Illinois.

Hwang, Helen H.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

1997-01-01

151

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

152

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

Code of Federal Regulations, 2013 CFR

...Prohibitions against excessive use of petroleum or natural gas in mixtures-certifying...Prohibitions against excessive use of petroleum or natural gas in mixtures—certifying...powerplants, OFP may prohibit the use of petroleum or natural gas in such...

2013-01-01

153

Quantitative Fourier transform infrared analysis of gas phase cigarette smoke and other gas mixtures  

SciTech Connect

A new method for the analysis of selected components in complex gas mixtures has been developed utilizing a relatively inexpensive Fourier transform infrared spectrometer and a continuous flow gas cell. The method was used to monitor nitric oxide and nitrogen dioxide concentrations in cigarette smoke with time. Using multivariate least-square regression analysis, it is possible to simultaneously quantitate both NO and NO{sub 2}, even in the presence of overlapping peaks. Using this method, the oxidation of nitric oxide in the presence of isoprene in cigarette smoke and in a model system was followed with time. The method also can be applied to other compounds in smoke or to any other gaseous mixture.

Cueto, R.; Church, D.F.; Pryor, W.A. (Louisiana State Univ., Baton Rouge (USA))

1989-03-01

154

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

DOEpatents

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.

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

1988-04-27

155

Magnetic resonance imaging of convection in laser-polarized xenon R. W. Mair,1  

E-print Network

Magnetic resonance imaging of convection in laser-polarized xenon R. W. Mair,1 C.-H. Tseng,1,2 G. P and diffusion of laser-polarized xenon (129 Xe) gas undergoing convection above evaporating laser-polarized liquid xenon. The large xenon NMR signal provided by the laser-polarization technique allows more rapid

Walsworth, Ronald L.

156

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

NASA Astrophysics Data System (ADS)

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.

Huang, Her-Yueh

2010-11-01

157

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

Microsoft Academic Search

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.

Fei Dong; Hongmei Lou; Akio Kodama; Motonobu Goto; Tsutomu Hirose

1999-01-01

158

New gas mixtures for Resistive Plate Chambers operated in avalanche mode  

NASA Astrophysics Data System (ADS)

The possibility of using gas mixtures containing Helium, to overcome some of the problems encountered with standard gas mixture employed up to now for Resistive Plate Chambers, is studied here. New and interesting experimental results are reported, opening a possible original path of investigation in this field.

Abbrescia, M.; Cassano, V.; Nuzzo, S.; Piscitelli, G.; Vadruccio, D.; Zaza, S.

2012-01-01

159

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

DOEpatents

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.

Aines, Roger D.

2013-03-12

160

Liquid xenon excimer laser  

SciTech Connect

The characteristics of the first excimer laser and the history of its creation are presented. The threshold lasing conditions and the modern theory of active media are considered, and the prospects for the development of excimer lasers operating on condensed inert gases are discussed. It is shown that in experiments on pumping liquid xenon, lasing was obtained simultaneously on excimers of several types, including excimers in liquid and gas phases. (special issue devoted to the 80th anniversary of academician n g basov's birth)

Molchanov, Alexander G [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2003-01-31

161

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

E-print Network

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

Kushner, Mark

162

Critical Viscosity of Xenon team  

NASA Technical Reports Server (NTRS)

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.

2001-01-01

163

Critical Viscosity of Xenon team  

NASA Technical Reports Server (NTRS)

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.

2001-01-01

164

Thermodynamics and transport properties of metal\\/inert-gas mixtures used for arc welding  

Microsoft Academic Search

The knowledge of thermodynamics and transport properties of gas mixtures at high temperature is important for many industrial applications. Spark ignition, re-entry problems of space-vehicles, gas dischargers, arc welding, and circuit breakers can be mentioned as examples. This paper focuses on metal\\/inert-gas mixtures in the temperature range from 300 to 30,000K, which are important for arc welding processes. As metals

T. Hoffmann; G. Baldea; U. Riedel

2009-01-01

165

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

SciTech Connect

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.

Bychkov, Yu. I., E-mail: bych-yu@yandex.ru; Yampolskaya, S. A.; Yastremskii, A. G. [Russian Academy of Sciences, Institute of High Current Electronics, Siberian Branch (Russian Federation)

2013-05-15

166

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

SciTech Connect

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

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

1982-01-01

167

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

Code of Federal Regulations, 2013 CFR

... Prohibition against excessive use of petroleum or natural gas in mixtures-electing... Prohibition against excessive use of petroleum or natural gas in mixtures—electing...feasible for a unit to use a mixture of petroleum or natural gas and an alternate...

2013-01-01

168

Measurement of the Vaporization Enthalpy of Complex Mixtures by Correlation-Gas Chromatography. The Vaporization Enthalpy of  

E-print Network

Measurement of the Vaporization Enthalpy of Complex Mixtures by Correlation-Gas Chromatography of correlation-gas chromatography to measure the vaporization enthalpy {l g Hm(298.15 K)} of complex mixtures obtained for the mixture. Correlation-gas chromatography is applicable in obtaining the vaporization

Chickos, James S.

169

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

Code of Federal Regulations, 2014 CFR

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

2014-01-01

170

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

Code of Federal Regulations, 2012 CFR

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

2012-01-01

171

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

Code of Federal Regulations, 2011 CFR

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

2011-01-01

172

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

Code of Federal Regulations, 2010 CFR

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

2010-01-01

173

Measurement of the Vaporization Enthalpy of Complex Mixtures by Correlation-Gas Chromatography. The  

E-print Network

Measurement of the Vaporization Enthalpy of Complex Mixtures by Correlation-Gas Chromatography April 21, 2005. Revised Manuscript Received June 2, 2005 The use of correlation-gas chromatography using gas chromatography. Some variance in composition with the literature values has been observed

Chickos, James S.

174

Primordial Terrestrial Xenon Revisited  

NASA Astrophysics Data System (ADS)

Xenon solar wind composition revealed by Genesis matches mathematically derived primordial terrestrial xenon with high precision, except for 136Xe and 134Xe. This can be explained by modification of fission yields in open systems.

Meshik, A. P.; Pravdivtseva, O. V.; Hohenberg, C. M.

2014-09-01

175

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

PubMed Central

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

Weinrich, Michael; Worcester, David L.

2014-01-01

176

Hyperpolarized Xenon for NMR and MRI Applications  

PubMed Central

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

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

2012-01-01

177

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

PubMed

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

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

2012-01-01

178

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

PubMed Central

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

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

2012-01-01

179

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

Code of Federal Regulations, 2014 CFR

...efficiency; and (3) No alternate power supply exists, as required under...these regulations. (c) Solar mixtures. OFE will grant...for the use of a mixture of solar energy (including wind, tide...natural gas, where: (1) Solar energy will account for...

2014-01-01

180

Results of wire chamber ageing tests with CH4- and DME-based gas mixtures  

Microsoft Academic Search

Results are presented of ageing tests performed on single-wire proportional counters under controlled conditions. The rate of the detector ageing with methane mixtures has been found to be independent of the anode and cathode materials used, and also of the purity of the gas. The rate of ageing for DME mixtures, on the other hand, appears to depend on the

Roger Bouclier; M Capéans-Garrido; C. Garabatos; R. D. Heuer; M. Jeanrenaud; T. C. Meyer; Fabio Sauli; K. Silander

1994-01-01

181

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...

182

RAPID COMMUNICATION: Ionisation and attachment coefficients measured in nitrogen and difluorodichloromethane gas mixtures  

Microsoft Academic Search

In view of contradiction in the dielectric strength of the CF2Cl2\\/N2 gas mixture reported by different investigators, the authors report the Townsend first ionisation coefficient alpha and the electron attachment coefficient eta measured in that gas mixture with various mixing ratios using the steady-state Townsend method over the range 40

Y. Qiu; X. Ren; Z. Y. Liu

1990-01-01

183

Transport Parameters of Electron Swarms in SF6 and Argon Gas Mixtures  

Microsoft Academic Search

The electron swarm growth processes in SF6-Ar gas mixtures have been studied by a pulsed Townsend method over the range 32.24<= E\\/N <= 564.2 Td (1 Td=10-21 V\\\\cdotm2), where E is the electric field and N is the gas density of the mixture. The variation patterns as functions of the density-reduced electric field of the effective ionization coefficient \\\\baralpha, electron

Deng-Ming Xiao; Hong-Lei Li; Ya-Zhu Chen

2000-01-01

184

Determination of concentrations in ternary and quaternary molecular gas mixtures using femtosecond Raman spectroscopy  

Microsoft Academic Search

Measurements of concentrations in gas mixtures of three and four molecular components are presented. They rely on a femtosecond time-resolved pump-probe technique based on Raman-induced polarization spectroscopy. The rotational time response of the molecular gas mixture is measured as a function of the pump-probe time delay. No selective frequency tunability is needed as the molecular rotational spectra are excited within

H. Tran; B. Lavorel; O. Faucher; R. Saint-Loup; P. Joubert

2002-01-01

185

Rarefied gas flow of binary mixtures through long channels with triangular and trapezoidal cross sections  

Microsoft Academic Search

The flow of binary gas mixtures through long micro-channels with triangular and trapezoidal cross sections is investigated\\u000a in the whole range of the Knudsen number. The flow is driven by pressure and concentration gradients. The McCormack kinetic\\u000a model is utilized to simulate the rarefied flow of the gas mixture, and the kinetic equations are solved by an upgraded discrete\\u000a velocity

Lajos Szalmas; Dimitris Valougeorgis

2010-01-01

186

Oxygen sensor for monitoring gas mixtures containing hydrocarbons  

DOEpatents

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.

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

1996-01-01

187

Oxygen sensor for monitoring gas mixtures containing hydrocarbons  

DOEpatents

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.

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

1996-03-12

188

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

189

The Enriched Xenon Observatory  

SciTech Connect

The Enriched Xenon Observatory (EXO) experiment will search for neutrinoless double beta decay of {sup 136}Xe. The EXO Collaboration is actively pursuing both liquid-phase and gas-phase Xe detector technologies with scalability to the ton-scale. The search for neutrinoless double beta decay of {sup 136}Xe is especially attractive because of the possibility of tagging the resulting Ba daughter ion, eliminating all sources of background other than the two neutrino decay mode. EXO-200, the first phase of the project, is a liquid Xe time projection chamber with 200 kg of Xe enriched to 80% in {sup 136}Xe. EXO-200, which does not include Ba-tagging, will begin taking data in 2009, with two-year sensitivity to the half-life for neutrinoless double beta decay of 6.4x10{sup 25} years. This corresponds to an effective Majorana neutrino mass of 0.13 to 0.19 eV.

Dolinski, M. J. [Stanford University Physics Department, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States)

2009-12-17

190

Stationary shock wave in a two-temperature gas-solid particle mixture with account of melting  

Microsoft Academic Search

An analysis is made for various types of shock waves in a mixtures of gas and solid particles with account of their melting and the real kinetic equation of melting. The mixture flow is equilibrium in velocity and nonequilibrium in temperature of the gas and condensed phases. The existence of the predicted types of mixture flows, in particular, a flow

A. V. Fedorov

1994-01-01

191

Separation of Methane and Carbon Dioxide Gas Mixtures by Pressure Swing Adsorption  

Microsoft Academic Search

Two pressure swing adsorption processes for separation of methane and carbon dioxide gas mixtures are described. One process simultaneously produces a high purity CH4 and a high purity CO2 product with high recoveries of both components from the feed gas. The other process only produces a high purity CH4 product with high recovery. Test data for these processes are reported

Shivaji Sircar

1988-01-01

192

Solution of the Diffusion Equations in a Gas Centrifuge for Separation of Multi component Mixtures  

Microsoft Academic Search

The demand for stable isotopes in physical and chemical research and in medical diagnostics is growing, and the gas centrifuge process is able to provide large quantities of stable isotopes. A set of diffusion equations describing separation in a gas centrifuge for a multi component mixture is established. These equations involve general diffusion coefficients. Using the radial averaging method and

Chuntong Ying; Zhixiong Guo; Houston G. Wood

1996-01-01

193

Prediction of gas tungsten arc welding properties in mixtures of argon and hydrogen  

Microsoft Academic Search

A theory of gas tungsten arc welding (GTAW) arcs that treats the tungsten electrode, the arc, and the workpiece as a unified system has been applied to make predictions in two dimensions of the temperature distributions in the arc, the tungsten cathode, and the workpiece, for any given arc current and gas mixture. Predictions of arc temperatures, radii, and voltages

John J. Lowke; Richard Morrow; Jawad Haidar; Anthony B. Murphy

1997-01-01

194

First Results from XENON100  

E-print Network

First Results from XENON100 For the XENON100 Collaboration Rafael F. Lang Columbia University rafael.lang@astro.columbia.edu #12;Rafael F. Lang (Columbia): First Results from XENON100 2 The XENON Università di Bologna Jiao Tong University Shanghai #12;Rafael F. Lang (Columbia): First Results from XENON

Weaver, Harold A. "Hal"

195

Diffusion of xenon (1); tridecane (2)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A `Gases in Gases, Liquids and their Mixtures' of Volume 15 `Diffusion in Gases, Liquids and Electrolytes' of Landolt-Börnstein Group IV `Physical Chemistry'. It is part of the chapter of the chapter `Diffusion in Pure Gases' and contains data on diffusion of (1) xenon; (2) tridecane

Winkelmann, J.

196

Nanostructure synthesis from high velocity gas mixture flows  

NASA Astrophysics Data System (ADS)

The synthesis of nanostructures is an emerging field of science, modern physics and technologies. The gas dynamic methods have become the instrument of fundamental researches and new basis of vacuum technologies. The gas jet deposition has taken important place in surface modification: deposition of metal, semiconductor, polymer films. History of rarefied gas dynamics and space sciences gave birth to fundamental knowledge for the progress in vacuum nanoscience and nanotechnology. Diamond synthesis holds a special place using the chemical vapor deposition method, based on processes in low density gases. The science on nanostructure synthesis now is on the boundary of new breakthroughs.

Rebrov, Aleksey K.

2014-12-01

197

Gas-puff Z pinches with D2 and D2Ar mixtures  

Microsoft Academic Search

Results obtained with the University of California, Irvine gas-puff Z-pinch experiment are described for deuterium and deuterium-argon mixtures. This experiment utilizes a hollow cylindrical gas puff injected between electrodes driven by a 4.8-kJ capacitor bank. Various gas compositions have been tested, including pure deuterium, 90% D2-10% Ar, and up to 10% D2-90% Ar. We have observed the stages of collapse

J. Bailey; Y. Ettinger; A. Fisher; N. Rostoker

1982-01-01

198

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

DOEpatents

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.

Owen, Thomas E.; Miller, Michael A.

2007-03-13

199

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

DOEpatents

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.

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

2010-08-24

200

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

Code of Federal Regulations, 2011 CFR

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

2011-01-01

201

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

Code of Federal Regulations, 2010 CFR

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

2010-01-01

202

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

Code of Federal Regulations, 2014 CFR

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

2014-01-01

203

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

Code of Federal Regulations, 2012 CFR

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

2012-01-01

204

Xenon Isotopes in Irradiated and Unirradiated Samples of ALH84001  

NASA Astrophysics Data System (ADS)

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.

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

1995-09-01

205

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

Microsoft Academic Search

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

Filimonova E; G. Naidis

2010-01-01

206

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

Microsoft Academic Search

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 (CFâ)âO, CFâ, BFâ, GeFâ, WFâ, SiFâ, in combination with a compound selected from the group consisting of TMPD, TMBI, TMAE,

S. R. Hunter; L. G. Christophorou

1990-01-01

207

Detection of krypton in xenon for dark matter applications  

E-print Network

We extend our technique for observing very small concentrations of impurities in xenon gas to the problem of krypton detection. We use a conventional mass spectrometer to identify the krypton content of the xenon, but we improve the sensitivity of the device by about five orders of magnitude with a liquid nitrogen cold trap. We find that the absolute krypton concentration of the xenon can be inferred from the mass spectrometry measurements, and we identify krypton signals at concentrations as low as 0.5x10^{-12} mol/mol (Kr/Xe). This technique simplifies the monitoring of krypton backgrounds for WIMP dark matter searches in liquid xenon.

Dobi, Attila; Hall, Carter; Langford, Thomas; Slutsky, Simon; Yen, Yung-Ruey

2011-01-01

208

Gas-phase separations of complex tryptic peptide mixtures.  

PubMed

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

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

2001-02-01

209

Two-phase turbine engines. [using gas-liquid mixture accelerated in nozzles  

NASA Technical Reports Server (NTRS)

A description is given of a two-phase turbine which utilizes a uniform mixture of gas and liquid accelerated in nozzles of the types reported by Elliott and Weinberg (1968). The mixture acts directly on an axial flow or tangential impulse turbine or is separated into gas and liquid streams which operate separately on a gas turbine and a hydraulic turbine. The basic two-phase cycles are examined, taking into account working fluids, aspects of nozzle expansion, details of turbine cycle operation, and the effect of mixture ratio variation. Attention is also given to two-phase nozzle efficiency, two-phase turbine operating characteristics and efficiencies, separator turbines, and impulse turbine experiments.

Elliott, D. G.; Hays, L. G.

1976-01-01

210

Experimental Characterization and Molecular Study of Natural Gas Mixtures  

E-print Network

. Phase Boundary Data for the Isochoric 2. ............................................... 111 Table 30. Natural Gas Main Constituents ............................................................... 114 Table 31. Dipole Moment, Quadrupole... for the density determinations when compared to accurate standards. Finally, this work proposed a new mixing rule to incorporate isomeric effects into cubic equations of state. v v DEDICATION...

Cristancho Blanco, Diego Edison

2011-08-08

211

Derivation of Hydrodynamic Equations for Binary Gas Mixture  

SciTech Connect

Velocities, densities, pressures, stresses, temperatures, heat fluxes and internal energies of each gas are individually defined. Moment equations for mass, momentum and energy of both gases are separately derived on basis of Boltzmann equations. Momentum equations have velocity relaxation terms between different gases and energy equations have velocity and temperature relaxation terms between those.

Kuwabara, Sinzi [Nagoya University, Inokashira 3-24-35 Mitaka-si, Tokyo (Japan); Yoshimura, Kazuyoshi [Mathematical Science and Information Technology Research Institute Miyamae 4-11-10 Suginami-ku, Tokyo (Japan)

2011-05-20

212

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

NASA Astrophysics Data System (ADS)

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 ? \\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 ? \\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.

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

2015-01-01

213

High-field NMR of adsorbed xenon polarized by laser pumping  

Microsoft Academic Search

Optical pumping has been used to enhance the pulsed NMR signal of 129Xe, allowing the detecting of low-pressure xenon gas and of xenon adsorbed on powdered solids. We observe an increase in sensitivity of more than 2 orders of magnitude over conventional NMR, the current limitation being the laser power. Adsorbed xenon is observed at 298 K on graphitized carbon

D. Raftery; H. Long; T. Meersmann; P. J. Grandinetti; L. Reven; A. Pines

1991-01-01

214

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

Microsoft Academic Search

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

D. Porcelli; G. J. Wasserburg

1995-01-01

215

EUV Radiation of Xenon Plasma Streams Generated by Magnetoplasma I.E. Garkusha1  

E-print Network

EUV Radiation of Xenon Plasma Streams Generated by Magnetoplasma Compressor I.E. Garkusha1 , V generation lithography. In both approaches xenon has advantage to be used as working gas due to considerably. This paper presents the investigations xenon plasma streams generated by magnetoplasma compressor (MPC

Harilal, S. S.

216

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

217

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

218

Mixing in Wave Processes Propagating in Gas Mixtures (Review)  

Microsoft Academic Search

A review is made of up-to-date investigations in the field of physicomathematical modeling of mixing of solid particles with high-velocity gas flows arising under the action on shock waves, compression waves, and expansion waves on unstable dust deposits on the boundaries of channels or plates and in cavities, as well as on free clouds of particles. In particular, experiments in

A. V. Fedorov

2004-01-01

219

Diffusion of relativistic gas mixtures in gravitational fields  

E-print Network

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

Gilberto M. Kremer

2013-03-26

220

Characterization and control of exhaust gas from diesel engine firing coal-water mixture  

SciTech Connect

Exhaust from the GE-TS single cylinder diesel engine, fitted with hardened metal, and diamond-tipped metal fuel injection nozzles, and firing coal-water mixture (CWM) has been characterized with respect to gas composition, particulate size distribution, and particulate filtration characteristics. The measured flue gas compositions are roughly in keeping with results from combustion calculations. The time variations of the hydrocarbon, CO, and NO{sub x} concentrations are also understood in terms of known reaction mechanisms.

Samuel, E.A.; Gal, E.; Mengel, M.; Arnold, M.

1990-03-01

221

Characterization and control of exhaust gas from diesel engine firing coal-water mixture  

SciTech Connect

Exhaust from the GE-TS single cylinder diesel engine, fitted with hardened metal, and diamond-tipped metal fuel injection nozzles, and firing coal-water mixture (CWM) has been characterized with respect to gas composition, particulate size distribution, and particulate filtration characteristics. The measured flue gas compositions are roughly in keeping with results from combustion calculations. The time variations of the hydrocarbon, CO, and NO[sub x] concentrations are also understood in terms of known reaction mechanisms.

Samuel, E.A.; Gal, E.; Mengel, M.; Arnold, M.

1990-03-01

222

Diffusion and virial coefficient in a mercury-argon gas mixture  

NASA Astrophysics Data System (ADS)

Theoretical and experimental data on molecular beams and the mutual diffusion coefficient (MDC) and second virial coefficient (SVC) for an Hg-Ar gas mixture as a representative of the mercuryinert gas family are matched on basis of the Morse potential and the relations of the molecular kinetic theory of rarefied gases. Tables of the MDC and SVC values in the temperature range of 200-2000 K are calculated, and estimates of their accuracy are presented.

Popov, V. N.; Fokin, L. R.

2013-04-01

223

Reduction of titania by methane-hydrogen-argon gas mixture  

SciTech Connect

Reduction of titania using methane-containing gas was investigated in a laboratory fixed-bed reactor in the temperature range 1,373 to 1,773 K. The reduction production product is titanium oxycarbide, which is a solid solution of TiC and TiO. At 1,373 K, the formation rate of TiC is very slow. The rate and extent of reaction increase with increasing temperature to 1,723 K. A further increase in temperature to 1,773 K does not affect the reaction rate and extent. An increase in methane concentration to 8 vol pct favors the reduction process. A further increase in methane concentration above 8 vol pct causes excessive carbon deposition, which has a negative effect on the reaction rate. Hydrogen partial pressure should be maintained above 35 vol pct to depress the cracking of methane. Addition of water vapor to the reducing gas strongly retards the reduction reaction, even at low concentrations of 1 to 2 vol pct. Carbon monoxide also depresses the reduction process, but its effect is significant only at higher concentrations, above 10 vol pct.

Zhang, G.; Ostrovski, O.

2000-02-01

224

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

NASA Astrophysics Data System (ADS)

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 ?m, from 0,3 ?m to 7 ?m. Differences, up to 20% in the average deposited energy due to different TEG mixtures were observed.

Kowalski, T. Z.

2015-03-01

225

Approximation of flammability region for natural gas-air-diluent mixture.  

PubMed

The growing implementation of exhaust gas recirculation (EGR) in reducing NO(x) emissions of engine is of paramount motivation to perform a fundamental research on the flammability characteristics of fuel-air-diluent mixtures. In this work, the influences of EGR on the flammability region of natural gas-air-diluent flames were experimentally studied in a constant volume bomb. An assumption of critical burning velocity at flammability limit is proposed to approximately determine the flammability region of these mixtures. Based on this assumption, an estimation of the flammability map for natural gas-air-diluent mixtures was obtained by using the empirical formula of burning velocity data. The flammability regions of natural gas-air mixtures with EGR are plotted versus the EGR rate. From the comparison of estimated results and experimental measurements, it is suggested that the accuracy of prediction is largely dependent upon the formula of burning velocity used. Meanwhile, the influence of pressure on the critical burning velocity at flammability limit is also investigated. On the basis of the pressure dependence criterion, the estimation was performed for the circumstance of high temperature and pressure, and the prediction results still agree well with those of experiments. PMID:15990227

Liao, S Y; Jiang, D M; Huang, Z H; Cheng, Q; Gao, J; Hu, Y

2005-10-17

226

Influence of Mixture Quality on Nonlinear Combustion Process of Natural Gas Engine  

Microsoft Academic Search

Combustion characteristic in a spark ignition natural gas engine was studied under different conditions of mixture quality based on chaos theory, in order to estimate nonlinear dynamic level in combustion system, we reconstructed attractor of combustion system using Indicated Mean Effective Pressure (IMEP), computed correlation dimensions and largest Lyapunov exponent (LLE) of the attractors, results show that there are low-dimensions

Yang Li-ping; Ma Xiu-zhen; Song En-zhe

2010-01-01

227

Experimental determination of the Townsend coefficient for Argon-CO2 gas mixtures at high fields  

E-print Network

The first Townsend coefficient for Ar-CO2 based gas mixtures has been measured over a wide range of reduced electric field. The experimental setup and the measurement technique are described here. A linear superposition model has also been successfully applied.

Auriemma, G; Pirozzi, G; Satriano, C

2003-01-01

228

Experimental determination of the Townsend coefficient for Argon–CO 2 gas mixtures at high fields  

Microsoft Academic Search

The first Townsend coefficient for Ar–CO2 based gas mixtures has been measured over a wide range of reduced electric field. The experimental setup and the measurement technique are described here. A linear superposition model has also been successfully applied.

G. Auriemma; D. Fidanza; G. Pirozzi; C. Satriano

2003-01-01

229

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)...

230

Assessment of breakdown voltage of SF6\\/N2 gas mixtures under non-uniform field  

Microsoft Academic Search

The dielectric breakdown of SF6\\/N2 gas mixture insulating system is believed to be sensitive to local irregularity of the electric field which may result from the presence of defects such as contaminants adhering to the electrode surface and surface roughness. Normally the surface roughness is produced from machine finishing and due to the aging of the system. This paper models

A. M. Mahdy

2011-01-01

231

Perturbation viscometry measurement of viscosity ratios for ternary gas mixtures and quantification of the errors  

Microsoft Academic Search

Perturbation viscometry measures the pressure changes in a gas mixture flowing through a capillary tube when the flow is perturbed by adding a small flow of one of the pure components. The pressure upstream of the capillary rises because of the increase in flow and then rises or falls because of the change in viscosity. These pressure changes are measured

P. A. Russell; B. A. Buffham; G. Mason; D. J. Richardson; M. J. Heslop

2004-01-01

232

TRANSIENT PROCESS IN GAS CENTRIFUGE CASCADES FOR SEPARATION OF MULTICOMPONENT ISOTOPE MIXTURES  

Microsoft Academic Search

The transient process is studied in gas centrifuge cascades for separation of multicomponent isotope mixtures. Two important practical factors, the holdups in connecting pipes among separation stages and material losses, are taken into account in the partial differential-difference equations that describe the concentration distribution of components. The equations are solved at each time step through the q-iteration method. The effects

Shi Zeng; Chuntong Ying

2001-01-01

233

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

E-print Network

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

Paris-Sud XI, Université de

234

Strong shock wave propagation in a mixture of a gas and dusty particles with counter pressure  

Microsoft Academic Search

The occurrence of a strong shock as a result of a sudden release of energy in a mixture of a gas and solid particles is considered. Self-similarity solutions exist, if the surrounding medium has a constant initial density and is at rest with negligible counter pressure. As the strong shock propagates, its strength will decay, and gradually the counter pressure

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

1982-01-01

235

Preparation of Neutron-activated Xenon for Liquid Xenon Detector Calibration  

E-print Network

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

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

2007-09-27

236

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

DOEpatents

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.

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

1990-01-01

237

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

DOEpatents

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.

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

1990-06-26

238

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

Code of Federal Regulations, 2010 CFR

...of cylinders with a mixture of compressed gas and other material. 173.305 Section...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.305...of cylinders with a mixture of compressed gas and other material. (a) Detailed...

2010-10-01

239

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

Code of Federal Regulations, 2011 CFR

...of cylinders with a mixture of compressed gas and other material. 173.305 Section...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.305...of cylinders with a mixture of compressed gas and other material. (a) Detailed...

2011-10-01

240

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

Code of Federal Regulations, 2014 CFR

...of cylinders with a mixture of compressed gas and other material. 173.305 Section...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.305...of cylinders with a mixture of compressed gas and other material. (a) Detailed...

2014-10-01

241

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

Code of Federal Regulations, 2012 CFR

...of cylinders with a mixture of compressed gas and other material. 173.305 Section...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.305...of cylinders with a mixture of compressed gas and other material. (a) Detailed...

2012-10-01

242

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

Code of Federal Regulations, 2013 CFR

...of cylinders with a mixture of compressed gas and other material. 173.305 Section...REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.305...of cylinders with a mixture of compressed gas and other material. (a) Detailed...

2013-10-01

243

Removal of carbon dioxide from gas mixtures by wollastonite  

NASA Astrophysics Data System (ADS)

Wollastonite synthesis and decomposition were analyzed from the viewpoint of thermodynamics (using the TERRA software). It is shown that wollastonite synthesis from limestone and silica takes place at a minimum content of nitrogen (10-5 N2) with a release of carbon dioxide. The synthesis temperature is T ? 560 K. Wollastonite is decomposed in the presence of flue gas (4N2) with limestone and silica formation and burial of carbon dioxide in the form of CaCO3(c). Wollastonite decomposition temperature is T ? 420 K. The cyclic reciprocating process for complete removal of carbon dioxide by wollastonite is suggested. Four strokes of the reciprocating system with the fixed temperatures of wollastonite decomposition (T=300 K) and wollastonite synthesis (T=560 K) are presented. Total energy consumption (T = 560 K) is ? I ? 130 kJ/mole, 30 % of energy is spent for heating and 70 % of energy is spent for chemical reaction. This is comparable with the heat of CO2 solution in ethanolamin.

Engelsht, V. S.; Muratalieva, V. Zh.

2013-09-01

244

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

Microsoft Academic Search

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 (0.05–0.4m3h?1), leading to empty bed residence times as low as 17.1s, and by changing the concentrations of gas-phase styrene (0.01–6.3gm?3) and acetone (0.01–8.9gm?3). The total

Eldon R. Rene; Radka Špa?ková; María C. Veiga; Christian Kennes

2010-01-01

245

Preparation of Calibration Gas Mixtures Using a Dynamic Volumetric Method for Environmental Monitoring  

NASA Astrophysics Data System (ADS)

It is difficult to produce and maintain the quality of calibration gas mixtures stable and reliable in gas cylinders for the identification and quantification of trace environmental contaminants. Dynamic method has attracted an attention because immediate and on-site generation of calibration gas mixture is achievable in the range of percent, sub-ppm, and micro-mole fraction. The dynamic method for the preparation of standard reference gas/vapour mixtures was carried out using polymeric permeation membrane. Permeation behaviour of various organic compounds including aliphatic and aromatic hydrocarbons and chlorohydrocarbons was tested through semi-permeable silicone polymer and fluoropolymers. Experimental results showed the constant permeation rate of target compounds under the constant temperature condition. The permeation rate, however, was largely influenced by chemical components, membrane materials, and temperature change. Mole fractions of generated vapour were calculated using the mass loss of permeation tubes and mass-flow rate of carrier gas. Dynamic volumetric techniques can be applicable for the generation of standard reference materials for the calibration of various types of organics (volatile organic compounds, polycyclic aromatic hydrocarbons, etc) in ambient air and water. This technology is also applicable to develop novel materials for passive samplers for long-term environmental monitoring.

Lee, S.; Lee, W.; Oh, S.

2008-12-01

246

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

E-print Network

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 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 proce...

Bates, Richard; 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

247

Electrochemical separation and concentration of sulfur containing gases from gas mixtures  

DOEpatents

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.

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

1981-01-01

248

A Kinetic Model for Gas Mixtures Based on a Fokker-Planck Equation  

NASA Astrophysics Data System (ADS)

We present a generalized nonlinear Fokker-Planck equation, which describes the dynamics of rarefied monatomic gas mixture flows. The devised kinetic model leads to correct transfer of energy and momentum between gas species and to consistent evolution of molecular stresses and heat fluxes with respect to the generalized Boltzmann equation. Thus, the correct diffusion coefficient together with the mixture viscosity and mixture heat conductivity coefficients are obtained. The strength of the presented model lies on the computational efficiency, which is due to the fact that the resulting stochastic processes are continuous in time. Therefore, unlike in Direct Simulation Monte Carlo (DSMC), here simulated particles do not collide with each other, but move along independent continuous stochastic paths. Another aspect of the new Fokker-Planck model equation is that here the effect of collisions is described via drift and diffusion type processes. Accordingly, a scheme can be derived for which the time step size limitation of the corresponding numerical simulation becomes independent of the Knudsen number. Consequently, this leads to more efficient simulations, especially in low or intermediate Knudsen numbers. Results are presented for helium-argon mixture in a one dimensional geometry. The calculated mixture viscosity is found to be in accordance with experimental data, which reveals the accuracy and relevance of the approach.

Gorji, Hossein; Jenny, Patrick

2012-05-01

249

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

250

Cosmic ray tests of a GEM-based TPC prototype operated in Ar-CF4-isobutane gas mixtures  

E-print Network

Argon with an admixture of CF4 is expected to be a good candidate for the gas mixture to be used for a time projection chamber (TPC) in the future linear collider experiment because of its small transverse diffusion of drift electrons especially under a strong magnetic field. In order to confirm the superiority of this gas mixture over conventional TPC gases we carried out cosmic ray tests using a GEM-based TPC operated mostly in Ar-CF4-isobutane mixtures under 0 - 1 T axial magnetic fields. The measured gas properties such as gas gain and transverse diffusion constant as well as the observed spatial resolution are presented.

Kobayashi, M; Tomioka, T; Aoza, A; Bito, H; Fujii, K; Higashi, T; Hiramatsu, K; Ikematsu, K; Ishikawa, A; Kato, Y; Kuroiwa, H; Matsuda, T; Nitoh, O; Ohta, H; Sakai, K; Settles, R D; Sugiyama, A; Tsuji, H; Watanabe, T; Yamaoka, H; Yazu, T

2010-01-01

251

Cosmic ray tests of a GEM-based TPC prototype operated in Ar-CF4-isobutane gas mixtures  

E-print Network

Argon with an admixture of CF4 is expected to be a good candidate for the gas mixture to be used for a time projection chamber (TPC) in the future linear collider experiment because of its small transverse diffusion of drift electrons especially under a strong magnetic field. In order to confirm the superiority of this gas mixture over conventional TPC gases we carried out cosmic ray tests using a GEM-based TPC operated mostly in Ar-CF4-isobutane mixtures under 0 - 1 T axial magnetic fields. The measured gas properties such as gas gain and transverse diffusion constant as well as the observed spatial resolution are presented.

M. Kobayashi; R. Yonamine; T. Tomioka; A. Aoza; H. Bito; K. Fujii; T. Higashi; K. Hiramatsu; K. Ikematsu; A. Ishikawa; Y. Kato; H. Kuroiwa; T. Matsuda; O. Nitoh; H. Ohta; K. Sakai; R. D. Settles; A. Sugiyama; H. Tsuji; T. Watanabe; H. Yamaoka; T. Yazu

2011-02-13

252

HXeOBr in a xenon matrix  

SciTech Connect

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.

Khriachtchev, Leonid; Tapio, Salla; Domanskaya, Alexandra V.; Raesaenen, Markku [Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 (Finland); Isokoski, Karoliina [Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Lundell, Jan [Department of Chemistry, University of Jyvaeskylae, P.O. Box 35, FIN-40014 Jyvaeskylae (Finland)

2011-03-28

253

Environmental Applications of Stable Xenon and Radioxenon Monitoring  

SciTech Connect

Improved detection capabilities are needed at several Department of Energy sites to make remedial decisions about facilities and landfill cleanup. For facility monitoring air samples can be collected from within a facility and analyzed for short lived radioxenons to estimate inventories of residual plutonium holdup within the facility. For landfill cleanup activities soil gas sampling for xenon isotopes can be used to define the locations of spent fuel and transuranic wastes. Short-lived radioxenon isotopes are continuously produced by spontaneous fission of plutonium-240 in transuranic wastes. Large volume soil-gas samples provide extremely sensitive measurement of radioxenon in the subsurface; a characteristic of transuranic waste. The analysis employs a modified Automated Radioxenon Sampling and Analysis (ARSA) system. Proof of principle measurements at a Hanford Site liquid waste disposal site showed xenon-133 at levels in soil gas are approximately 16,000 times the detection limit and lower levels of xenon-135 from the spontaneous fission of plutonium-240 were also measured. Stable xenon isotopes are also produced by spontaneous fission but are subject to background concentrations in ambient air samples (facilities) but less so in soil gas where free exchange with ambient air is restricted. Rare gas mass spectrometry is used for highly precise stable xenon isotopic measurements. Stable xenon isotopic ratios from fission are distinct from natural xenon background ratios. Neutron capture on xenon-135 produces an excess of xenon-136 above fission ratios and thus provides a means of distinguishing reactor sources (e.g. spent fuel) from separated transuranic materials (plutonium).

Dresel, P. Evan; Olsen, Khris B.; Hayes, James C.; McIntyre, Justin I.; Waichler, Scott R.; Kennedy, B. M.

2008-06-01

254

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

PubMed Central

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

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

255

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

PubMed

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

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

256

KEY COMPARISON: International comparison CCQM-K54: Primary standard gas mixtures of hexane in methane  

NASA Astrophysics Data System (ADS)

The aim of this comparison is to evaluate the gravimetry and purity verification of gas mixtures prepared by introducing a liquid into a gas cylinder. This type of preparation is well known from, e.g., ethanol in nitrogen/air (CCQM-K4), and n-hexane in synthetic natural gas (CCQM-K16). The choice for n-hexane in methane is based on the relevance of natural gas primary standard mixtures and higher hydrocarbons in synthetic natural gas (for, e.g., dew point calibrations). Furthermore, n-hexane is relatively straightforward to analyse using a GC/FID (gas chromatograph equipped with a flame ionisation detector) with good repeatability. Eight laboratories participated. After the data evaluation, the result of one laboratory was eliminated to arrive at a consistent subset. The quality of the fitted line was not overly good, leading to small discrepancies in the degrees-of-equivalence calculated for three other laboratories. Only four laboratories are consistent with the KCRV. 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 (MRA).

van der Veen, Adriaan M. H.; Chander, Hima; Ziel, Paul R.; Wessel, Rob M.; de Leer, Ed W. B.; Smeulders, Damian; Besley, Laurie; Kato, Kenji; Watanabe, Takuro; Seog Kim, Jin; Woo, Jin-Chun; Bae, Hyun Kil; Doo Kim, Yong; Pérez Castorena, Alejandro; Rangel Murillo, Francisco; Serrano Caballero, Victor M.; Ramírez Nambo, Carlos; de Jesús Avila Salas, Manuel; Konopelko, Leonid A.; Popova, Tatjana A.; Pankratov, V. V.; Kovrizhnih, M. A.; Kuzmina, T. A.; Efremova, O. V.; Kustikov, Yury A.; Milton, Martin J. T.; Vargha, Gergely; Guenther, Frank R.; Rhoderick, George C.

2010-01-01

257

Xenon Isotope Releases from Buried Transuranic Waste  

NASA Astrophysics Data System (ADS)

Xenon is an inert rare gas produced as a fission product in nuclear reactors and through spontaneous fission of some transuranic isotopes. Thus, xenon will be released from buried transuranic waste. Two complementary methods are used to measure xenon isotopes: radiometric analysis for short-lived radioxenon isotopes and mass spectrometry for detection of stable xenon isotopes. Initial measurements near disposal facilities at the U.S. Department of Energy's Hanford Site show radioxenon and stable xenon isotopic signatures that are indicative of transuranic waste. Radioxenon analysis has greater sensitivity due to the lower background concentrations and indicates spontaneous fission due to the short half life of the isotopes. Stable isotope ratios may be used to distinguish irradiated fuel sources from pure spontaneous fission sources and are not as dependent on rapid release from the waste form. The release rate is dependent on the type of waste and container integrity and is the greatest unknown in application of this technique. Numerical multi-phase transport modeling of burial grounds at the Idaho National Engineering and Environmental Laboratory indicates that, under generalized conditions, the radioxenon isotopes will diffuse away from the waste and be found in the soil cap and adjacent to the burial ground at levels many orders of magnitude above the detection limit.

Dresel, P. E.; Waichler, S. R.; Kennedy, B. M.; Hayes, J. C.; McIntyre, J. I.; Giles, J. R.; Sondrup, A. J.

2004-12-01

258

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

PubMed Central

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

2013-01-01

259

Kinetic Solution of the Structure of a Shock Wave in a Non-Reactive Gas Mixture  

NASA Astrophysics Data System (ADS)

The multi-species Boltzmann equation is numerically integrated to characterize the internal structure of a Mach 3 shock wave in a hard sphere gas. The collision integral is evaluated by the conservative discrete ordinate method of Tcheremissine [1]. There was excellent agreement of macroscopic variables with those of Kosuge, Aoki, and Takata. [2] The effect of species concentration and mass ratio on the behavior of macroscopic variables and distribution functions in the structure of the shock wave is considered for both two and three-species gas mixtures. In a binary mixture of gases with different masses and varying concentrations, the temperature overshoot of the parallel component of temperature near the center of the shock wave is highest for the heavy component when the concentration of the heavy component is the smallest. A physical basis for the temperature overshoot is put forth.

Josyula, Eswar; Vedula, Prakash; Bailey, William F.; Suchyta, Casimir J.

2011-05-01

260

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

SciTech Connect

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.

Dong, F.; Lou, H.; Kodama, Akio; Goto, Motonobu; Hirose, Tsutomu [Kumamoto Univ., Kurokami, Kumamoto (Japan)] [Kumamoto Univ., Kurokami, Kumamoto (Japan)

1999-01-01

261

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

NASA Astrophysics Data System (ADS)

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(?, ?)12C reaction, a central problem in nuclear astrophysics.

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

2006-05-01

262

Electron swarm parameters in a CO2:N2:He:CO gas mixture  

Microsoft Academic Search

Various electron transport parameters, namely the centre of mass drift velocity W, the diffusion coefficients DL and DT and the Townsend primary ionisation coefficient alpha T, have been measured in a particular CO2:N2:He:CO gas mixture. Measurements were made for a range of E\\/N varying from 100 to 500 Td and compared with two-term Boltzmann calculation. The differences between the experimental

A. B. Wedding

1985-01-01

263

Negative pion transfer process in a hydrogen-containing gas mixture  

Microsoft Academic Search

Annihilation ?-rays of ?0 and pionic X-rays were measured in the gas mixtures of H2+Z and CH4+Z systems (Z=He, Ne, Ar and Kr). Pion capture probability of hydrogen atom was obtained from the annihilation ?-ray counts\\u000a and the capture probability of Z atom was obtained from the pionic X-ray intensities. Transfer rates were determined from\\u000a the data based on a

T. Muroyama; A. Shinohara; T. Saito; A. Yokoyama; K. Takamiya; S. Morimoto; K. Nakanishi; H. Baba; T. Miura; Y. Hamajima; T. Kaneko; H. Muramatsu; S. Kojima; M. Furukawa

1999-01-01

264

MOBILITIES OF POSITIVE IONS IN SOME GAS MIXTURES USED IN PROPORTIONAL AND DRIFT CHAMBERS  

E-print Network

de Blanc est vérifiée pour tous les mélanges gazeux étudiés, sauf dans le cas des mélanges argon-isobutane methylal concentration in argon-isobutane-methylal. The law permits the calculation of ion mobility in any proportional chambers or drift chambers with gas mixtures, using isobutane as a quencher. The positive ions

Paris-Sud XI, Université de

265

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

266

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

267

Combustion gas and NO emission characteristics of hazardous waste mixture particles in a fixed bed  

Microsoft Academic Search

Experiments with fixed-bed incinerators were carried out to model the combustion characteristics and gas emission characteristics\\u000a of hazardous waste mixture particles in a grate furnace. The results indicate that combustion can be divided into three stages:\\u000a ignition, main combustion and combustion completion stage. According to the various concentrations of O2, CO2 and CO, the main combustion stage can be subdivided

Ling Tao; Guangbo Zhao; Rui Sun

2011-01-01

268

Performance of resistive plate counters with freonless gas mixtures for measurements of cosmic ray muons  

Microsoft Academic Search

Various operational features of bakelite Resistive Plate Counters with a bulk resistivity of 1012?cm are studied with different argon, methane and isobutane mixtures, but avoiding freon as counter gas contribution. The efficiency and the time resolution of the detector as well as the cross-talk behavior of neighbored read-out pads are investigated for different voltages by use of cosmic ray muons.

S. Ganter; J. Wentz; A. Haungs; H. J. Mathes; H. Rebel

1998-01-01

269

Variation of density with composition for natural gas mixtures in the supercritical region  

E-print Network

VARIATION OF DENSITY WITH COMPOSITION FOR NATURAL GAS MIXTURES IN THE SUPERCRITICAL REGION A Thesis by WIDIA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: ____________________________ James C. Holste (Co...

Widia

2004-11-15

270

Shock and detonation wave diffraction at a sudden expansion in gas–particle mixtures  

Microsoft Academic Search

Numerical modeling of the propagation of shock and detonation waves is carried out in a duct with an abrupt expansion for\\u000a a heterogeneous mixture of fine particles of aluminum and oxygen. A considerable difference from corresponding flows in pure\\u000a gas is found. The influence of the size and mass loading of particles on the flow and shock wave structure behind

A. V. Fedorov; T. A. Khmel; Yu. V. Kratova

2008-01-01

271

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

DOEpatents

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.

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

2010-04-13

272

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

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

273

Process and catalyst for converting synthesis gas to liquid hydrocarbon mixture  

DOEpatents

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.

Rao, V. Udaya S. (Monroeville, PA); Gormley, Robert J. (Pittsburgh, PA)

1987-01-01

274

Optical absorption method of natural gas component analysis in real time. Part II. Analysis of mixtures of arbitrary composition  

NASA Astrophysics Data System (ADS)

The present paper continues the presentation of the results of studies started in [1]. The referred paper reports the development of the optical method for component analysis of natural gas mixtures with different compositions, allowing conducting measurements in real time. The method is based on the measurement of the absorption coefficients for the analyzed gas mixture at several wavelengths within the infrared region of the spectrum (7-14 ?m), with the selected number and values of wavelengths depending on the category of the gas mixture. The resulting accuracy of the determination of the main components of gas mixtures including methane, ethane, propane, butane, pentane and carbon dioxide is sufficient for the use of the developed method for the monitoring of the component composition of natural gas in pipelines.

Kireev, S. V.; Podolyako, E. M.; Simanovsky, I. G.; Shnyrev, S. L.

2012-10-01

275

Controlled pulse-etching with xenon difluoride  

Microsoft Academic Search

A gas-phase, room-temperature, plasmaless isotropic etching system has been used for bulk and thin film silicon etching. A computer controlled multi-chambered etcher is used to provide precisely metered pulses of xenon difluoride (XeF2) gas to the etch chamber. Etch rates as high as 15 microns per minute have been observed. The etch appears to have infinite selectivity to many common

Patrick B. Chu; Jeffrey T. Chen; Richard Yeht; Gisela Lin; Jeff C. P. Huang; B. A. Warneke; S. J. Pister

1997-01-01

276

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

NASA Technical Reports Server (NTRS)

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.

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

1971-01-01

277

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

DOEpatents

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.

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

2010-11-09

278

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

DOEpatents

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.

Aines, Roger D.; Bourcier, William L.

2014-08-19

279

Energy of the quasi-free electron in argon, krypton and xenon Xianbo Shi a,b  

E-print Network

Energy of the quasi-free electron in argon, krypton and xenon Xianbo Shi a,b , Luxi Li a,b , C. M ionization measurements of various high-n molecular Rydberg states doped into argon, krypton and xenon, krypton and xenon from the dilute gas up to the density of the triple point liquid, on both critical

Findley, Gary L.

280

"Liquid Xenon R&D for Future Large-Scale Dark-Matter Detectors" , D B Cline1  

E-print Network

1 "Liquid Xenon R&D for Future Large-Scale Dark-Matter Detectors" M Atac1 , D B Cline1 , K T Mc in the direct observation of nuclear recoils. The ZEPLIN-II detector (with 35-kg of liquid xenon medium), which. These tests will include: 1. photon amplification in liquid and gas xenon using a CsI internal photo

McDonald, Kirk

281

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

NASA Astrophysics Data System (ADS)

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.

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

282

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

283

Effect of hydrogen impurity on the electrical characteristics of neon-argon gas mixtures. I. Measurement of ionization coefficients  

Microsoft Academic Search

The effect of H2 on the breakdown potential and Townsend ionization coefficients for Ne-A mixtures were measured by the luminous-flux method. Both argon and hydrogen form Penning mixtures with neon. The breakdown potentials for Ne-A gas mixtures are determined by the Penning reaction, Nem+A?Ne+e+A+, between metastable neon (Nem) and ground state A atoms. At low H2 concentrations (<0.1%) the breakdown

A. K. Bhattacharya

1983-01-01

284

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

SciTech Connect

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

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

1995-12-31

285

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

USGS Publications Warehouse

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.

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

2001-01-01

286

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

Microsoft Academic Search

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

S Oh; C Bae

2004-01-01

287

Ionization and scintillation of nuclear recoils in gaseous xenon  

E-print Network

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 $\\alpha$-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.

Renner, J; 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; Morata, J A Hernando; 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; Vidal, J Muñoz; da Luz, H Natal; Navarro, G; Nebot-Guinot, M; Palma, R; Pérez, J; Aparicio, J L Pérez; Ripoll, L; Rodríguez, A; Rodríguez, J; Santos, F P; Santos, J M F dos; 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

2014-01-01

288

Ionization and scintillation of nuclear recoils in gaseous xenon  

E-print Network

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 $\\alpha$-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.

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

2014-09-09

289

A Xenon Condenser with a Remote Liquid Storage Vessel  

E-print Network

We describe the design and operation of a system for xenon liquefaction in which the condenser is separated from the liquid storage vessel. The condenser is cooled by a pulse tube cryocooler, while the vessel is cooled only by the liquid xenon itself. This arrangement facilitates liquid particle detector research by allowing easy access to the upper and lower flanges of the vessel. We find that an external xenon gas pump is useful for increasing the rate at which cooling power is delivered to the vessel, and we present measurements of the power and efficiency of the apparatus.

S. Slutsky; Y. -R. Yen; H. Breuer; A. Dobi; C. Hall; T. Langford; D. S. Leonard; L. J. Kaufman; V. Strickland; N. Voskanian

2009-07-25

290

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

NASA Astrophysics Data System (ADS)

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.

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

2009-06-01

291

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

NASA Technical Reports Server (NTRS)

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.

Offenhaeuser, F.

1987-01-01

292

Gas-phase concentration, purification, and identification of whole proteins from complex mixtures.  

PubMed

Five proteins present in a relatively complex mixture derived from a whole cell lysate fraction of E. coli have been concentrated, purified, and dissociated in the gas phase, using a quadrupole ion trap mass spectrometer. Concentration of intact protein ions was effected using gas-phase ion/ion proton-transfer reactions in conjunction with mass-to-charge dependent ion "parking" to accumulate protein ions initially dispersed over a range of charge states into a single lower charge state. Sequential ion isolation events interspersed with additional ion parking ion/ion reaction periods were used to "charge-state purify" the protein ion of interest. Five of the most abundant protein components present in the mixture were subjected to this concentration/purification procedure and then dissociated by collisional activation of their intact multiply charged precursor ions. Four of the five proteins were subsequently identified by matching the uninterpreted product ion spectra against a partially annotated protein sequence database, coupled with a novel scoring scheme weighted for the relative abundances of the experimentally observed product ions and the frequency of fragmentations occurring at preferential cleavage sites. The identification of these proteins illustrates the potential of this "top-down" protein identification approach to reduce the reliance on condensed-phase chemistries and extensive separations for complex protein mixture analysis. PMID:12071744

Reid, Gavin E; Shang, Hao; Hogan, Jason M; Lee, Gil U; McLuckey, Scott A

2002-06-26

293

Two-dimensional gas-phase separations coupled to mass spectrometry for analysis of complex mixtures.  

PubMed

Ion mobility spectrometry (IMS) has been explored for decades, and its versatility in separation and identification of gas-phase ions 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 (TOF) MS. Implementation of FAIMS/IMS and IMS/MS interfaces using electrodynamic ion funnels greatly improves sensitivity. Evaluation of FAIMS/IMS/TOF performance for 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 peak capacities in analyses of tryptic peptides are approximately 500 for FAIMS/IMS separations and approximately 10(6) for 3-D FAIMS/IMS/MS, providing a potential platform for ultrahigh-throughput analyses of complex mixtures. PMID:16194103

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

2005-10-01

294

Pulsed electron-beam-sustained discharge in oxygen-containing gas mixtures: electrical characteristics, spectroscopy,and singlet oxygen yield  

Microsoft Academic Search

The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume (â18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition

Nikolai P Vagin; Andrei A Ionin; Yu M Klimachev; A A Kotkov; Yu P Podmarkov; L V Seleznev; D V Sinitsyn; M P Frolov; Nikolai N Yuryshev; Igor V Kochetov; A P Napartovich; G D Hager

2004-01-01

295

Purging means and method for Xenon arc lamps  

NASA Technical Reports Server (NTRS)

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.

Miller, C. G. (inventor)

1973-01-01

296

Xenon in chondritic metal.  

NASA Astrophysics Data System (ADS)

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

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

1989-10-01

297

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

E-print Network

sinker magnetic suspension densimeter has been used first to determine densities of pure component�s densities for which very reliable data are available. After validating its performance, the densities of four light natural gas mixtures, containing...

Ejaz, Saquib

2007-09-17

298

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

NASA Astrophysics Data System (ADS)

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.

Clarke, Peter; Varghese, Philip; Goldstein, David

2014-12-01

299

Precision measurement of timing RPC gas mixtures with laser-beam induced electrons  

NASA Astrophysics Data System (ADS)

The main goals of a new test facility at Helmholtz-Zentrum Dresden-Rossendorf are precision measurements of the electron drift velocity and the Townsend coefficient of gases at atmospheric pressure in the strongest ever used homogenous electrical fields and the search for new RPC gas mixtures to substitute the climate harmful Freon. Picosecond UV laser pulses were focused into a sub-millimeter gas gap to initialize a defined tiny charge. These gaps are formed by electrodes of low-resistive ceramics or high-resistive float glass. The charge multiplication occurs in a strong homogeneous electric field of up to 100 kV/cm. Electron-ion pairs were generated in a cylindrical micro-volume by multi-photon ionization. The laser-pulse repetition rate ranges from 1 Hz to a few kHz. The RPC time resolution has been measured for different gases. First results of the Townsend coefficient at 100 kV/cm show a strong disagreement between the present measurement and Magboltz simulations for the typical timing RPC gas mixture C2F4H2/SF6/i-C4H10, while the measured electron drift velocities are in a good agreement with the model predictions.

Naumann, L.; Siebold, M.; Kaspar, M.; Kämpfer, B.; Kotte, R.; Laso Garcia, A.; Löser, M.; Schramm, U.; Wüstenfeld, J.

2014-10-01

300

Evaluation of the age of landfill gas methane in landfill gas-natural gas mixtures using co-occurring constituents.  

PubMed

At a municipal solid waste landfill in southern California (USA) overlying a natural gas reservoir, methane was detected at concentrations of up to 40% (by volume) in perimeter soil gas probes. Stable isotope and (14)C values of methane together with gas composition (major components and volatile organic compounds) data were evaluated to assess the relative contributions of landfill gas and natural gas to the measured methane concentrations. The data was further used to estimate the residence time of the landfill gas in the probes. Results showed that up to 37% of the measured methane was derived from landfill gas. In addition, the landfill gas in the probe samples has undergone extensive alteration due to dissolution of carbon dioxide in pore water. Data further indicates that the measured methane was released from the waste approximately 1.2 to 9.4 years ago, rather than representing evidence of an ongoing release. PMID:23660592

Kerfoot, Henry B; Hagedorn, Benjamin; Verwiel, Mark

2013-06-01

301

Requirements for Xenon International  

SciTech Connect

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.

Hayes, James C.; Ely, James H.

2013-09-26

302

Study of RPC gas mixtures for the ARGO-YBJ experiment  

E-print Network

The ARGO-YBJ experiment consists of a RPC carpet to be operated at the Yangbajing laboratory (Tibet, P.R. China), 4300 m a.s.l., and devoted to the detection of showers initiated by photon primaries in the energy range 100 GeV - 20 TeV. The measurement technique, namely the timing on the shower front with a few tens of particles, requires RPC operation with 1 ns time resolution, low strip multiplicity, high efficiency and low single counting rate. We have tested RPCs with many gas mixtures, at sea level, in order to optimize these parameters. The results of this study are reported.

B. Bartoli; R. Buonomo; E. Calloni; S. Catalanotti; B. D'Ettorre Piazzoli; G. Di Sciascio; M. Iacovacci

2000-02-24

303

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

NASA Technical Reports Server (NTRS)

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.

Nealy, J. E.

1975-01-01

304

Transport coefficients and Onsager reciprocal relations in the kinetic theory of dense gas mixtures  

NASA Astrophysics Data System (ADS)

The Chapman-Enskog method is used here to obtain expressions for the physical transport coefficients (i.e., the coefficients of diffusion, thermal diffusion, and heat conduction), and it is shown that these coefficients satisfy the Onsager reciprocal relations. It is also shown that for dense gas mixtures, the di vector in the Chapman-Enskog method can no longer be identified with the thermodynamic vector of diffusion forces, as in the case of rarefied gases. Heat and mass transfer equations are obtained in a form that is identical to the form of the corresponding equations in irreversible process thermodynamics.

Kurochkin, V. I.; Makarenko, S. F.; Tirskii, G. A.

1984-04-01

305

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

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

306

The incorporation and migration of a single xenon atom in ceria  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

307

Gas mixtures for spark gap closing switches with emphasis on efficiency of operation  

NASA Astrophysics Data System (ADS)

The efficient operation of a spark gap closing switch requires a gaseous medium with large breakdown strength, low conduction voltage, and a short formative time lag. Gas properties necessary to achieve these requirements are identified and discussed. Based on available knowledge of such properties, a number of binary (e.g., c-C4F8, or 1-C3F6, or n-C4F10, or C3F8, or C6F6 in Ar or He or H2) and ternary gas mixtures (e.g., c-C4F8, or n-C4F10, or C3F8 in Ar or He + C2H2 or another low ionization onset additive) have been identified which may be suitable for use in spark gap closing switches.

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

308

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

SciTech Connect

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.

Tournier, Jean-Michel P.; El-Genk, Mohamed S. [Institute for Space and Nuclear Power Studies and Chemical and Nuclear Engineering Department, University of New Mexico, Albuquerque, NM 87131 (United States)

2008-01-21

309

[Use of helium-oxygen gas mixtures in acute obstructive respiratory insufficiencies].  

PubMed

Therapeutic use of helium has been described since 1930. Its main action is to reduce bronchial resistances and consequently overall respiratory work. Helium is substituted for nitrogen. The effects of inhaling a helium-oxygen mixture result exclusively from the physicochemical properties of helium: very low density, high kinetic viscosity. With the advent of selective bronchodilators, use of helium was rapidly abandoned until recently with new interest for the treatment of severe acute asthma. We review the literature on the physical properties of helium-oxygen mixtures and propose an analysis of their therapeutic use in severe acute asthma as well as other indications such as acute episodes of obstructive bronchopneumonia and obstruction of the upper airways. Due to the non-invasive nature of this technique, its easy use with spontaneous ventilation and the large body of theoretical data emphasizing its adaptation for therapeutic use, helium-oxygen gas mixtures offer an important therapeutic option for treating severe diseases with poor prognosis. A multicentric national study is under way to validate its use early by emergency ambulatory units for the treatment of severe acute asthma. PMID:9616816

L'Her, E; Renault, A; Mouline, J; Garo, B; Boles, J M

1997-01-01

310

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

SciTech Connect

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

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

2006-12-15

311

Converging xenon shock waves driven by megagauss magnetic fields  

SciTech Connect

We attempted to implode a conducting metal linear at high velocity, and our failure to do so led to switching, or rapidly transferring the field from pushing an aluminum conductor to snow-plowing a half-atmosphere of xenon gas. We successfully initiated convergent xenon gas shocks with the use of a magnetohydrodynamic switch and coaxial high-explosive, flux-compression generators. Principal diagnostics used to study the imploding xenon gas were /sup 133/Xe radioactive tracers, continuous x-ray absorption, and neutron output. We compressed the xenon gas about five to sixfold at a velocity of 10 cm/..mu..s at a radius of 4 cm. The snowplow efficiency was good; going from 13- to 4-cm radius, we lost only about 20% of the mass. The temperature of the imploded sheath was determined by mixing deuterium with the xenon and measuring the neutron output. Using reasonable assumptions about the amount, density, and uniformity of the compressed gas, we estimate that we reached temperatures as high as 155 eV. Energy-loss mechanisms that we encountered included wall ablation and Taylor instabilities of the back surface.

Shearer, J.W.; Steinberg, D.J.

1986-07-01

312

Buffer-gas pressure influence on multiphoton absorption in SF6-N2 mixtures  

NASA Astrophysics Data System (ADS)

In this article the results of pulsed IR photoacoustic spectroscopy measurements of multiphoton absorption and relaxation processes in SF6-N2 mixtures are presented. The total average number of absorbed photons per one absorbing molecule (basic physical quantity which characterized multiphoton processes) during the laser pulse total is used and analyzed with a generalized coupled two-level model. This type of analysis is based on buffer-gas pressure (pbuff) functional behavior of total and calculation of its partial values depending on collisions, coll, and laser fluence, ?, influence. Using different methods of photoacoustic spectroscopy, collisionaly induced rotational and vibrational to translational relaxation process parameters (?rot and ?V-T, respectively) are quantitatively obtained and used to determine partial values of coll, rot, and V-T. It will be shown that a method based on ?total/?p functional dependence on pbuff and laser fluence ? can be used to confirm or predict the existence of some processes during the laser pulse, such as dissociation or strong vibrational to vibrational energy transfer, which can contribute to the total amount of energy absorbed into the investigated sample. This could allow one to apply this method and control laser field-molecule interaction in different gas mixtures, and help one to understand multiphoton absorption processes in detail.

Markushev, D. D.; Terzi?, M.; Jovanovi?-Kurepa, J.

2003-01-01

313

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

PubMed

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

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

2005-03-25

314

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

NASA Astrophysics Data System (ADS)

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.

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

315

Photoionization detector for the detection of xenon light  

SciTech Connect

A photionization detector is described with a high quantum efficiency at wavelengths shorter than about 2000 A. This instrument, coupled to a xenon gas scintillation proportional counter has an energy resolution of 9.5% FWHM at 6 keV. The vapor pressure and absorption coefficient of TMAE are measured and the prospects of an imaging gas scintillation proportional counter are discussed.

Anderson, D.F.

1980-01-01

316

Xenon-Ion Drilling of Tungsten Films  

NASA Technical Reports Server (NTRS)

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.

Garner, C. E.

1986-01-01

317

Influence of nitrogen–argon gas mixtures on reactive magnetron sputtering of hard Si–C–N films  

Microsoft Academic Search

Si–C–N films were deposited on p-type Si(100) substrates by dc magnetron co-sputtering of silicon and carbon using a single sputter target with variable Si\\/C area ratios in nitrogen–argon mixtures. The film characteristics were primarily controlled by the argon concentration (0–75%) in the gas mixture at a fixed 40% silicon fraction in the magnetron erosion track area. The total pressure and

Jaroslav Vl?ek; Martin Kormunda; Ji??? ???zek; Vratislav Pe?ina; Josef Zemek

2002-01-01

318

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

319

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

PubMed

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

Rene, Eldon R; Spa?ková, Radka; Veiga, María C; Kennes, Christian

2010-12-15

320

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

NASA Astrophysics Data System (ADS)

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

Jee, Sang Eun

321

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)

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.

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

1976-01-01

322

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...

323

In vivo Mapping of Local Cerebral Blood Flow by Xenon-Enhanced Computed Tomography  

Microsoft Academic Search

A noninvasive technique has been developed to measure and display local cerebral blood flow (LCBF) in vivo. In this procedure, nonradioactive xenon gas is inhaled and the temporal changes in radiographic enhancement produced by the inhalation are measured by sequential computerized tomography. The time-dependent xenon concentrations in various anatomical units in the brain are used to derive both the local

David Gur; Walter F. Good; Sidney K. Wolfson; Howard Yonas; Leonard Shabason

1982-01-01

324

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

SciTech Connect

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).

Dorris, S.E.; Balachandran

1996-06-01

325

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

SciTech Connect

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).

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

2005-07-01

326

Inductively coupled plasma etching of hafnium-indium-zinc oxide using chlorine based gas mixtures  

NASA Astrophysics Data System (ADS)

We report the etching characteristics of a stacked hafnium-indium-zinc oxide (HIZO) with a photoresist using the gas mixture of chlorine and argon (Cl2/Ar). The etching behaviors of HIZO have been investigated in terms of a source power, a bias power and a chamber pressure. As the concentration of Cl2 was increased compared to pure Ar, the etch rate of HIZO film was found slightly different from that of indium-zinc oxide (IZO) film. Moreover, to investigate the etching mechanism systematically, various inspections were carried out such as atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) depending on the portion of Cl2. Additionally, we compared the etching mechanism of HIZO film with IZO film to confirm the difference of chemical bonds caused by the influence of hafnium doping.

Choi, Yong-Hee; Jang, Ho-Kyun; Jin, Jun-Eon; Joo, Min-Kyu; Piao, Mingxing; Shin, Jong Mok; Kim, Jae-Sung; Na, Junhong; Kim, Gyu Tae

2014-04-01

327

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

SciTech Connect

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.

HEDENGREN, D.C.

2000-01-31

328

Spontaneous symmetry breaking and inversion-line spectroscopy in gas mixtures  

E-print Network

According to quantum mechanics chiral molecules, that is molecules that rotate the polarization of light, should not exist. The simplest molecules which can be chiral have four or more atoms with two arrangements of minimal potential energy that are equivalent up to a parity operation. Chiral molecules correspond to states localized in one potential energy minimum and can not be stationary states of the Schr\\"odinger equation. A possible solution of the paradox can be founded on the idea of spontaneous symmetry breaking. This idea was behind work we did previously involving a localization phase transition: at low pressure the molecules are delocalized between the two minima of the potential energy while at higher pressure they become localized in one minimum due to the intermolecular dipole-dipole interactions. Evidence for such a transition is provided by measurements of the inversion spectrum of ammonia and deuterated ammonia at different pressures. A previously proposed model gives a satisfactory account of the empirical results without free parameters. In this paper, we extend this model to gas mixtures. We find that also in these systems a phase transition takes place at a critical pressure which depends on the composition of the mixture. Moreover, we derive formulas giving the dependence of the inversion frequencies on the pressure. These predictions are susceptible to experimental test.

Carlo Presilla; Giovanni Jona-Lasinio

2015-02-20

329

Spontaneous symmetry breaking and inversion-line spectroscopy in gas mixtures  

NASA Astrophysics Data System (ADS)

According to quantum mechanics, chiral molecules, that is, molecules that rotate the polarization of light, should not exist. The simplest molecules which can be chiral have four or more atoms with two arrangements of minimal potential energy that are equivalent up to a parity operation. Chiral molecules correspond to states localized in one potential energy minimum and can not be stationary states of the Schrödinger equation. A possible solution of the paradox can be founded on the idea of spontaneous symmetry breaking. This idea was behind work we did previously involving a localization phase transition: at low pressure, the molecules are delocalized between the two minima of the potential energy while at higher pressure they become localized in one minimum due to the intermolecular dipole-dipole interactions. Evidence for such a transition is provided by measurements of the inversion spectrum of ammonia and deuterated ammonia at different pressures. A previously proposed model gives a satisfactory account of the empirical results without free parameters. In this paper, we extend this model to gas mixtures. We find that also in these systems a phase transition takes place at a critical pressure which depends on the composition of the mixture. Moreover, we derive formulas giving the dependence of the inversion frequencies on the pressure. These predictions are susceptible to experimental test.

Presilla, Carlo; Jona-Lasinio, Giovanni

2015-02-01

330

Parametric Study of Localized Plasma Mechanisms in ICP reactors using HBr/Cl2 Gas Mixtures  

NASA Astrophysics Data System (ADS)

HBr/Cl2 gas mixture is often used for etching poly-Si. As the dimensions of the transistors are reduced, profile control, high poly-Si etch rate, high selectivity over the gate oxide, low ion-induced damage become critical. We have investigated detailed plasma mechanism for HBr/Cl2 and applied to two dimensional plasma transport code in order to investigate localized behavior of HBr/Cl2 plasma chemistry. The initial mechanism for HBr/Cl2 is investigated using well mixed model. For a HBr/Cl2 plasma, the nominal conditions are 1000 Watts of input power, 5 mTorr of pressure, and a gas mixture of HBr/Cl2 = 20/80%. The major ions are Cl+, Cl2+ and Br+. The well mixed computational results show that approximately HBr/Cl2 = 55/45% will produce the equal amount of Br+ and Cl+ ions. The generation of Br+ and Cl+ are almost exclusively from the ionization of ground states and excited states of Br and Cl, where Br and Cl is mostly formed from the electron dissociation of HBr and Cl2, respectively. Cl2+ is mostly from the ionization of ground state Cl2. For a two dimensional transport code, we have used latest version of INDUCT, (2) which solves a set of time dependent fluid equations for electron and ions self-consistently with Poisson's equation for the electric potential. The dominant plasma reactions are identified for several locations in the reactor chamber including the areas below the coils, close to the side wall, center of the reactor, and above the wafer. (1) E. Meeks and J. W. Shon, IEEE Trans. on Plasma Sci., 23, 539, 1995. (2) P. Vitello, J. N. Bardsley, G. Dipeso, and G. J. Parker, IEEE Trans. on Plasma Sci., 24, 123, 1996.

Shon, J. W.; Vitello, P.

1996-10-01

331

Corona inception voltage in statorettes with various gas-solid dielectric systems  

NASA Technical Reports Server (NTRS)

Corona inception voltage was calculated and measured for three statorettes in several gases and gas mixtures at pressures from 50.8 to 1270 torr. In helium the corona inception voltage was lowest, and in air it was highest. In argon and mixtures of helium and xenon the corona inception voltage was between that of air and helium. Correlation between experimental and calculated data was good.

Bollenbacher, G.; Kempke, E. E., Jr.

1972-01-01

332

Bronchial imaging in humans using xenon K-edge dichromography  

NASA Astrophysics Data System (ADS)

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

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

1998-02-01

333

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

PubMed Central

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

2013-01-01

334

ISOTOPIC COMPOSITION OF PRIMORDIAL XENON  

Microsoft Academic Search

A large excess of Xe¹²⁹ and secondary anomalous abundances for ; many of the other isotopes of xenon were previously reported for the meteorite, ; Richardton. Similar secondary anomalies in xenon are reported for the meteorite ; Murray. For every isotope other than Xe¹²⁹, the ratio of the Murray ; percent abundance to the Richardton percent abundance was the same

J. Reynolds

1960-01-01

335

Xenon Recirculation-Purification with a Heat Exchanger  

E-print Network

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling power is spent to compensate losses from recirculation. The phase change during recondensing requires five times more cooling power than cooling the gas from ambient temperature to -100C (173 K). Thus, to reduce the cooling power requirements for large detectors, we propose to use the heat from the purified incoming gas to evaporate the outgoing xenon gas, by means of a heat exchanger. Generally, a heat exchanger would appear to be only of very limited use, since evaporation and liquefaction occur at zero temperature difference. However, the use of a recirculation pump reduces the pressure of the extracted liquid, forces it to evaporate, and thus cools it down. We show that this temperature difference can be used for an efficient heat exchange process. We investigate the use of a commercial parallel plate heat exchanger with a small liquid xenon detector. Although we expected to be limited by the available cooling power to flow rates of about 2 SLPM, rates in excess of 12 SLPM can easily be sustained, limited only by the pump speed and the impedance of the flow loop. The heat exchanger operates with an efficiency of (96.8 +/- 0.5)%. This opens the possibility for fast xenon gas recirculation in large-scale experiments, while minimizing thermal losses.

K. L. Giboni; E. Aprile; B. Choi; T. Haruyama; R. F. Lang; K. E. Lim; A. J. Melgarejo; G. Plante

2011-03-04

336

Shear Thinning in Xenon  

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

337

On-line analysis of complex hydrocarbon mixtures using comprehensive two-dimensional gas chromatography.  

PubMed

This paper discusses the first setup for on-line qualitative and quantitative comprehensive two-dimensional gas chromatography (GC × GC) of complex hydrocarbon mixtures. A built-in 4-port 2-way valve allows switching between flame ionization detection (FID) and time-of-flight mass spectrometry (TOF-MS) between runs, without the need to cool down and vent the MS. Proper selection of GC carrier gas flow rates enables maximal agreement between the obtained chromatograms in both configurations. For on-line analysis of reactor effluents, a dedicated sampling system allows automatic sampling of the hot reactor effluent gases and immediate injection of the sample on the GC × GC. To determine a complete effluent composition in a single run of the GC × GC, a subzero oven starting temperature was employed. Modulation is started when the oven temperature reaches 40°C, thus dividing the chromatogram in a conventional 1D and a comprehensive 2D part. This work illustrates the mature and robust character of GC × GC, extending its capabilities from mere laboratory use to on-line routine analysis for industrial processes in the (petro-)chemical industry. PMID:20444456

Van Geem, Kevin M; Pyl, Steven P; Reyniers, Marie-Françoise; Vercammen, Joeri; Beens, Jan; Marin, Guy B

2010-10-22

338

Portable gas chromatograph with tunable retention and sensor array detection for determination of complex vapor mixtures.  

PubMed

A prototype portable gas chromatograph that combines a multiadsorbent preconcentrator/focuser, a tandem-column separation stage with individual column temperature control and junction point pressure modulation, and a detector consisting of an integrated array of polymer-coated surface acoustic wave microsensors is described. Using scheduled first-column stop-flow intervals and independent temperature programming of the two columns, it is possible to adjust the retention of eluting analyte vapors to maximize vapor recognition with the microsensor array and minimize the time of analysis. A retention window approach is combined with Monte Carlo simulations to guide retention tuning requirements and facilitate pattern recognition analyses. The determination of a 30-vapor mixture of common indoor air contaminants in < 10 min is demonstrated using ambient air as the carrier gas. Detection limits of < 10 ppb are achieved for the majority of compounds from a 1-L air sample on the basis of the most sensitive sensor in the array. Performance is assessed in the context of near-real-time indoor air quality monitoring applications. PMID:12659202

Lu, Chia-Jung; Whiting, Joshua; Sacks, Richard D; Zellers, Edward T

2003-03-15

339

Xenon-enhanced CT imaging of local pulmonary ventilation  

NASA Astrophysics Data System (ADS)

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.

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

1996-04-01

340

Determination of time-course change rate for arterial xenon using the time course of tissue xenon concentration in xenon-enhanced computed tomography  

SciTech Connect

In calculating tissue blood flow (TBF) according to the Fick principle, time-course information on arterial tracer concentration is indispensable and has a considerable influence on the accuracy of calculated TBF. In TBF measurement by xenon-enhanced computed tomography (Xe-CT), nonradioactive xenon gas is administered by inhalation as a tracer, and end-tidal xenon is used as a substitute for arterial xenon. There has been the assumption that the time-course change rate for end-tidal xenon concentration (Ke) and that for arterial xenon concentration (Ka) are substantially equal. Respiratory gas sampling is noninvasive to the patient and Ke can be easily measured by exponential curve fitting to end-tidal xenon concentrations. However, it is pointed out that there would be a large difference between Ke and Ka in many cases. The purpose of this work was to develop a method of determining the Ka value using the time course of tissue xenon concentration in Xe-CT. The authors incorporated Ka into the Kety autoradiographic equation as a parameter to be solved, and developed a method of least-squares to obtain the solution for Ka from the time-course changes in xenon concentration in the tissue. The authors applied this method of least-squares to the data from Xe-CT abdominal studies performed on 17 patients; the solution for Ka was found pixel by pixel in the spleen, and its Ka map was created for each patient. On the one hand, the authors obtained the average value of the Ka map of the spleen as the calculated Ka (Ka{sub calc}) for each patient. On the other hand, the authors measured Ka (Ka{sub meas}) using the time-course changes in CT enhancement in the abdominal aorta for each patient. There was a good correlation between Ka{sub calc} and Ka{sub meas} (r=0.966, P<0.0001), and these two Ka values were close to each other (Ka{sub calc}=0.935xKa{sub meas}+0.089). This demonstrates that Ka{sub calc} would be close to the true Ka value. Accuracy of TBF by Xe-CT can be improved with use of the average value of the Ka map of an organ like the spleen that has a single blood supply (only arterial inflow)

Sase, Shigeru; Takahashi, Hideaki; Ikeda, Hiroki; Kobayashi, Minoru; Matsumoto, Nobuyuki; Suzuki, Michihiro [Anzai Medical Co., Ltd., 3-9-15 Nishi-Shinagawa, Shinagawa-ku, Tokyo 141-0033 (Japan); Department of Internal Medicine, Division of Gastroenterology and Hepatology, School of Medicine, St. Marianna University, 2-16-1 Miyamae-ku, Sugao, Kawasaki 216-5811 (Japan)

2008-06-15

341

DUSTYBOX and DUSTYWAVE: two test problems for numerical simulations of two-fluid astrophysical dust-gas mixtures  

NASA Astrophysics Data System (ADS)

In this paper we present the analytic solutions for two test problems involving two-fluid mixtures of dust and gas in an astrophysical context. The solutions provide a means of benchmarking numerical codes designed to simulate the non-linear dynamics of dusty gas. The first problem, DUSTYBOX, consists of two interpenetrating homogeneous fluids moving with relative velocity difference. We provide exact solutions to the full non-linear problem for a range of drag formulations appropriate to astrophysical fluids (i.e. various prescriptions for Epstein and Stokes drag in different regimes). The second problem, DUSTYWAVE, consists of the propagation of linear acoustic waves in a two-fluid gas-dust mixture. We provide the analytic solution for the case when the two fluids are interacting via a linear drag term. Both test problems are simple to set up in any numerical code and can be run with periodic boundary conditions. The solutions we derive are completely general with respect to both the dust-to-gas ratio and the amplitude of the drag coefficient. A stability analysis of waves in a gas-dust system is also presented, showing that sound waves in an astrophysical dust-gas mixture are linearly stable.

Laibe, Guillaume; Price, Daniel J.

2011-12-01

342

High kinetic energy ion mobility spectrometer: quantitative analysis of gas mixtures with ion mobility spectrometry.  

PubMed

We present a high kinetic energy ion mobility spectrometer (HiKE-IMS) for quantitative gas analysis. Drift tube and reaction tube can be operated at reduced fields up to 110 Td. At such conditions the distribution of reactant ion water clusters is shifted toward smaller clusters. Due to the resulting presence of bare reactant ions (e.g., H3O(+)) and the kinetic control of the ionization process with decreasing reaction time, unlike conventional IMS, a quantitative detection with ppbv detection limits of low proton affine analytes even in humid gas mixtures containing high proton affine compounds is possible using a direct sample gas inlet. A significantly improved dynamic range compared to conventional IMS is achieved. An incremental change in reduced fields enables the observation of parameters like field dependent ion mobilites or analyte fragmentation. Also, the characteristic of the analyte signal with respect to the reduced reaction field gives insight into the ionization process of the analyte. Thus, HiKE-IMS enables substance identification by ion mobility and additional analytical information that are not observed with conventional IMS. The instrumental effort is similar to conventional desktop IMS with overall dimensions of the drift and reaction tube of 4 cm × 4 cm × 28.5 cm. However, the mobility resolution is limited and between 30 and 40. Because of the moisture independent ionization and the decrease in competing ion-molecule reactions, no preseparation or membrane inlet is necessary when the compounds of interest are distinguishable either by a significant difference in ion mobility or the additional analytical information. PMID:24937741

Langejuergen, Jens; Allers, Maria; Oermann, Jens; Kirk, Ansgar; Zimmermann, Stefan

2014-07-15

343

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

SciTech Connect

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.

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

1985-01-01

344

Development of mass measurement equipment using an electronic mass-comparator for gravimetric preparation of reference gas mixtures  

NASA Astrophysics Data System (ADS)

The gravimetric method is the most popular method for preparing reference gas mixtures with high accuracy. We have designed and manufactured novel mass measurement equipment for gravimetric preparation of reference gas mixtures. This equipment consists of an electronic mass-comparator with a maximum capacity of 15 kg and readability of 1 mg and an automatic cylinder exchanger. The structure of this equipment is simpler and the cost is much lower than a conventional mechanical knife-edge type large balance used for gravimetric preparation of primary gas mixtures in Japan. This cylinder exchanger can mount two cylinders alternatively on the weighing pan of the comparator. In this study, the performance of the equipment has been evaluated. At first, the linearity and repeatability of the mass measurement were evaluated using standard mass pieces. Then, binary gas mixtures of propane and nitrogen were prepared and compared with those prepared with the conventional knife-edge type balance. The comparison resulted in good consistency at the compatibility criterion described in ISO6143:2001.

Matsumoto, Nobuhiro; Watanabe, Takuro; Maruyama, Masaaki; Horimoto, Yoshiyuki; Maeda, Tsuneaki; Kato, Kenji

2004-06-01

345

Breathing Gas Mixtures Different from Air: An Adaptation for Survival under the Ice of a Facultative Air-Breathing Fish  

Microsoft Academic Search

Gaseous respiration by central mudminnows (Umbra limi), particularly their use of bubbles composed of gas mixtures other than air, may have evolved as an adaptation to the oxygen-depleted, carbon dioxide--rich water of winterkill lakes. Under simulated winterkill conditions, mudminnows frequently engulfed gaseous bubbles. Use of bubbles was not related to varying methane or nitrogen content (0 to 80 percent) when

John J. Magnuson; John W. Keller; Annamarie L. Beckel; George W. Gallepp

1983-01-01

346

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

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

347

Mass transfer by diffusion in many-temperature gas mixtures - Diffusion coefficients, evaluation of collision integrals, ion-neutral interaction potentials  

Microsoft Academic Search

In the present paper, diffusive mass-transfer phenomena occurring in partially ionized multicomponent gas mixtures are analyzed in the case where the action of the electric field predominates in the electromagnetic effect on the medium. The temperatures of the gas mixture components are assumed to differ. The analysis is based on kinetic equations for independent-particle distribution functions of the components with

Iu. N. Beliaev; V. A. Polianskii; E. G. Shapiro

1979-01-01

348

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

PubMed

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

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

2015-04-01

349

Automatic isochoric apparatus for PVT and phase equilibrium studies of natural gas mixtures  

E-print Network

hydrocarbon mixture dew points. The data also show that the AGA 8-DC92 equation of state has errors as large as 0.6% when predicting hydrocarbon mixture densities when its normal composition range is extrapolated....

Zhou, Jingjun

2009-05-15

350

Gas-puff Z pinches with D/sub 2/ and D/sub 2/-Ar mixtures  

SciTech Connect

Results obtained with the University of California, Irvine gas-puff Z-pinch experiment are described for deuterium and deuterium-argon mixtures. This experiment utilizes a hollow cylindrical gas puff injected between electrodes driven by a 4.8-kJ capacitor bank. Various gas compositions have been tested, including pure deuterium, 90% D/sub 2/-10% Ar, and up to 10% D/sub 2/-90% Ar. We have observed the stages of collapse and its rate, electron density at the pinch, neutron yield, and the time dependence of x-ray and neutron emission. When a 90% D/sub 2/-10% Ar mixture is injected, the plasma annulus is observed to separate into two columns which implode concentrically.

Bailey, J.; Ettinger, Y.; Fisher, A.; Rostoker, N.

1982-03-15

351

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

Microsoft Academic Search

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

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

1995-01-01

352

High pressure and temperature optical flow cell for near-infra-red spectroscopic analysis of gas mixtures.  

PubMed

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

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

2014-05-01

353

Property value estimation for inhaled therapeutic binary gas mixtures: He, Xe, N2O, and N2 with O2  

PubMed Central

Background The property values of therapeutic gas mixtures are important in designing devices, defining delivery parameters, and in understanding the therapeutic effects. In the medical related literature the vast majority of articles related to gas mixtures report property values only for the pure substances or estimates based on concentration weighted averages. However, if the molecular size or structures of the component gases are very different a more accurate estimate should be considered. Findings In this paper estimates based on kinetic theory are provided of density, viscosity, mean free path, thermal conductivity, specific heat at constant pressure, and diffusivity over a range of concentrations of He-O2, Xe-O2, N2O-O2 and N2-O2 mixtures at room (or normal) and body temperature, 20 and 37°C, respectively and at atmospheric pressure. Conclusions Property value estimations have been provided for therapeutic gas mixtures and compared to experimental values obtained from the literature where possible. PMID:22146153

2011-01-01

354

Environmental application of stable xenon and radioxenonmonitoring  

SciTech Connect

Characterization of transuranic waste is needed to makedecisions about waste site remediation. Soil-gas sampling for xenonisotopes can be used to define the locations of spent fuel andtransuranic wastes. Radioxenon in the subsurface is characteristic oftransuranic waste and can be measured with extreme sensitivity usinglarge-volume soilgas samples. Measurements at the Hanford Site showed133Xe and 135Xe levels indicative of 240Pu spontaneous fission. Stablexenon isotopic ratios from fission are distinct from atmospheric xenonbackground. Neutron capture by 135Xe produces an excess of 136Xe inreactor-produced xenon providing a means of distinguishing spent fuelfrom separated transuranic materials.

Dresel, P. Evan; Olsen, Khris B.; Hayes, James C.; McIntyre,Justin I.; Waichler, Scott R.; Milbrath, Brian D.; Cooper, Matt; Kennedy,B. Mack

2006-09-05

355

Sound Absorption and Dispersion along the Critical Isochore in Xenon  

Microsoft Academic Search

Ultrasonic and Brillouin absorption and velocity data along the critical isochore in xenon are reinterpreted in terms of modified theoretical expressions derived within the framework of the Fixman-Mistura theory. The new expressions mainly arise from avoiding the unjustified assumption of small dispersion near a liquid-gas critical point. Numerical analysis of the data shows quite satisfactory agreement between theory and experiment

Don Eden; Carl W. Garland; Jan Thoen

1972-01-01

356

LETTER TO THE EDITOR: Measurement of ionisation and attachment coefficients in gas mixtures of difluorodichloromethane and carbon dioxide  

Microsoft Academic Search

The Townsend first ionisation coefficient alpha and the electron attachment coefficient eta were measured in CF2Cl2\\/CO2 gas mixtures using the steady-state Townsend method over the range 35mixture ratios being 10\\/90, 25\\/75, 50\\/50, 75\\/25, and 90\\/10. The limiting E\\/p values derived from the pre-breakdown current growth measurements were in agreement with the results of static

Y. Qiu; X. Ren; Z. Y. Liu; M. C. Zhang

1989-01-01

357

Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 January--31 March 1995  

SciTech Connect

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.

Iglesia, E.

1995-04-24

358

Effect of focal size on the laser ignition of compressed natural gas-air mixture  

NASA Astrophysics Data System (ADS)

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.

Srivastava, Dhananjay Kumar; Wintner, Ernst; Agarwal, Avinash Kumar

2014-07-01

359

Gas-phase ion chemistry of NF3/SO2 mixtures  

NASA Astrophysics Data System (ADS)

The gas-phase ion chemistry of NF3/SO2 mixtures has been investigated by ion trap mass spectrometry and theoretical calculations. SO+ and SO2+ react efficiently with NF3 giving F(SO)+ and F(SO2)+. CAD experiments and thermochemical considerations support the exclusive formation of the sulfur-fluorine cations FSO+ and FSO2+. NF2+ is unreactive toward SO2, and NF3+ undergoes exclusively the efficient charge transfer. On the other hand, NF+ activates the OSO bond, with formation of SO+ and NO+. DFT and coupled cluster calculations indicate that these ionic products arise from a SO+-(FNO) ion-dipole complex, which dissociates into SO+ and FNO or NO+ and FSO. This intermediate is more stable than NF+ and SO2 by nearly 60 kcal mol-1. We have also located a less stable sulfur-nitrogen complex FNSO2+, whose formation explains the less efficient observed charge transfer between NF+ and SO2. The only observed negative ion-molecule reaction is the formation of FSO2- from the reaction between SO2- and NF3. Our investigated processes may be of interest for the plasma and the atmospheric chemistry of NF3, one of the gaseous compounds most extensively used in the electronic industry to perform etching and cleaning processes.

Antoniotti, Paola; Rabezzana, Roberto; Turco, Francesca; Borocci, Stefano; Bronzolino, Nicoletta; Grandinetti, Felice

2007-10-01

360

The nature of the heterogeneity of the isotopic composition of xenon in meteorites, terrestrial and lunar rocks  

Microsoft Academic Search

This paper discusses protogenic or solar xenon, the unique component of the primary gas cloud. Changes in the isotopic composition of primitive xenon are caused by the fission process of U-238 and Pu-244, and Cm-248, and by the B-decay of I-129 as well as by the formation of spalogenic xenon during the interaction of cosmic rays with barium and other

Gerling

1985-01-01

361

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

362

Solubilized xenon 133 lung scintigraphy  

SciTech Connect

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.

Oates, E.; Sarno, R.C.

1988-11-01

363

Imaging local cerebral blood flow by Xenon-enhanced computed tomography — Technical optimization procedures  

Microsoft Academic Search

Methods are described for non-invasive, computer-assisted serial scanning throghout the human brain during eight minutes of inhalation of 27%–30% Xenon gas in order to measure local cerebral blood flow (LCBF). Optimized Xenonenhanced computed tomography (XeCT) was achieved by 5-second scanning at one-minute intervals utilizing a state-of-the-art CT scanner and rapid delivery of Xenon gas via a face mask. Values for

J. S. Meyer; T. Shinohara; A. Imai; M. Kobari; F. Sakai; T. Hata; W. T. Oravez; G. M. Timpe; T. Deville; E. Solomon

1988-01-01

364

A photochemical answer to the 'xenon paradox'  

NASA Astrophysics Data System (ADS)

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

Hébrard; Marty, B.

2012-12-01

365

Analysis of the insulation characteristics of cC4F8\\/CO2 gas mixtures by the Monte Carlo method  

Microsoft Academic Search

This paper analyses the insulation characteristics of c-C4F8\\/CO2 gas mixtures using the Monte Carlo method with the null-collision technique and studies the possibility of applying that in the gas insulation of power equipment. The density-normalized effective ionization coefficient (alpha - eta)\\/N for c-C4F8\\/CO2 gas mixtures has been calculated using a sample of a pulsed Townsend discharge. The overall density-reduced electric

Xueli Liu; Jianwei Wang; Yanan Wang; Zhousheng Zhang; Dengming Xiao

2008-01-01

366

Single Ion Trapping for the Enriched Xenon Observatory  

SciTech Connect

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.

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

2006-03-28

367

Emission spectra of working mixtures of a HgBr\\/HgCl excimer lamp  

Microsoft Academic Search

A study of emission spectra of a gas-discharge plasma produced in a HgBr\\/HgCl excimer lamp, which is filled with multicomponent\\u000a working mixtures at atmospheric pressure (HgBr2 and HgCl2 with additions of molecular nitrogen and xenon), are reported. A gas-discharge plasma was produced by high-frequency (pulses\\u000a ?100 ns long with a repetition rate of up to 2000 Hz) barrier and surface

A. N. Malinin; N. N. Guivan; L. L. Shimon

2000-01-01

368

Method of and apparatus for measuring the mean concentration of thoron and/or radon in a gas mixture  

DOEpatents

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.

Lucas, Henry (P.O. Box 1454, Sedona, AZ 86336)

1990-01-01

369

Langmuir Probe and Optical Emission Spectroscopy Studies of Low-Pressure Gas Mixture of CO2 and N2  

Microsoft Academic Search

Optical emission spectroscopy was used to study a gas mixture glow discharge of CO2 and N2 at a total pressure of 1.2 Torr, a power of 100 W and a flow of 16.5 L\\/min. The emission bands were measured in the wavelength range of 200 nm to 900 nm. The principal species observed were O2+ (A2Piu --> X2Pig), CO+ (A2Pi

E. F. Mendez-Martinez; P. G. Reyes; D. Osorio-Gonzalez; F. Castillo; H. Martinez

2010-01-01

370

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

371

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

SciTech Connect

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.

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

1993-05-01

372

Experimental investigation of a surface DBD plasma actuator at atmospheric pressure in different N2/O2 gas mixtures  

NASA Astrophysics Data System (ADS)

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.

Audier, P.; Rabat, H.; Leroy, A.; Hong, D.

2014-12-01

373

A Method of Separating a Middle Component in Multicomponent Isotope Mixtures by Gas Centrifuge Cascades  

Microsoft Academic Search

Separating a certain middle component of isotopes from a multicomponent isotopic mixture is much more difficult than separating the two end isotope components. Numerical investigation revealed that by controlling the cut of a separation cascade, defined as the ratio of the product rate to the feed rate, it is always possible to separate a multicomponent mixture into two specified groups

SHI ZENG; CHUNTONG YING

2000-01-01

374

Use of a solid mixture containing diethylenetriamine\\/nitric oxide (DETANO) to liberate nitric oxide gas in the presence of horticultural produce to extend postharvest life  

Microsoft Academic Search

Postharvest treatment of fruit and vegetables with a low concentration of nitric oxide gas can extend postharvest life but application of nitric oxide by release from a gas cylinder is not feasible for many horticultural situations. This paper reports on development of a solid mixture to generate nitric oxide gas in the presence of horticultural produce. The solid NO-donor compound,

R. B. H. Wills; L. Soegiarto; M. C. Bowyer

2007-01-01

375

Separating Mixtures  

NSDL National Science Digital Library

Students learn how to classify materials as mixtures, elements or compounds and identify the properties of each type. The concept of separation of mixtures is also introduced since nearly every element or compound is found naturally in an impure state such as a mixture of two or more substances, and it is common that chemical engineers use separation techniques to separate mixtures into their individual components. For example, the separation of crude oil into purified hydrocarbons such as natural gas, gasoline, diesel, jet fuel and/or lubricants.

National Science Foundation GK-12 and Research Experience for Teachers (RET) Programs,

376

Development of a functionalized Xenon biosensor  

SciTech Connect

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.

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

377

ANALYTICAL METHOD FOR MEASURING TOTAL PROTIUM AND TOTAL DEUTERIUM IN A GAS MIXTURE CONTAINING H2, D2,AND HD VIA GAS CHAROMATOGRAPHY  

SciTech Connect

The most common analytical method of identifying and quantifying non-radioactive isotopic species of hydrogen is mass spectrometry. A low mass, high resolution mass spectrometer with adequate sensitivity and stability to identify and quantify hydrogen isotopes in the low ppm range is an expensive, complex instrument. A new analytical technique has been developed that measures both total protium (H) and total deuterium (D) in a gas mixture containing H{sub 2}, D{sub 2}, and HD using an inexpensive micro gas chromatograph (GC) with two molecular sieve columns. One column uses D{sub 2} as the carrier gas and the other uses H{sub 2} as the carrier gas. Laboratory tests have shown that when used in this configuration the GC can measure both total protium and total deuterium each with a detection and quantification limit of less than 20 ppm.

Sessions, H

2007-08-07

378

Using Point Reactor Models and Genetic Algorithms for On-Line Global Xenon Estimation in Nuclear Reactors  

Microsoft Academic Search

Estimation of xenon concentration at a given time instant is usually a difficult problem since the initial conditions are often unknown as well as a number of the model parameters. The feasibility of obtaining the model parameters of a point reactor xenon evolution model with genetic algorithms (GAs) has been investigated earlier using data obtained from a point reactor model

Tunc Aldemir; Giancarlo Torri; Marzio Marseguerra; Enrico Zio; Jeffrey A. Borkowski

2003-01-01

379

Gas emissions and engine behavior when gasoline-alcohol mixtures are used.  

PubMed

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

Arapatsakos, C I; Karkanis, A N; Sparis, P D

2003-09-01

380

Combustion Characteristics of a CO2 Mixture Methane & a Microturbine Cogeneration System utilizing Sewage Digester Gas  

Microsoft Academic Search

An attempt has been made to utilize biogas (sewage digester gas) as a fuel for gas turbines. The sewage digester gas utilized had low Btu, constituting 60% methane and 40% carbon dioxide. Conventional attempts necessitate the optimization of combustion systems to improve flame-holding and other characteristics to enable the use of biogas as gas turbine fuel. The novel approach taken

Tadashi KATAOKA; Teruyuki NAKAJIMA; Takahiro NAKAGAWA; Saburo YUASA

381

CMD-3 Liquid Xenon Calorimeter's signals processing  

E-print Network

CMD-3 Liquid Xenon Calorimeter's signals processing for timing measurements. Leonid Epshtein Budker connected to constitute 264 «towers»; signal of each tower is processed by electronic channel. Liquid Xenon

382

Analytical Modeling of Weld Bead Shape in Dry Hyperbaric GMAW Using Ar-He Chamber Gas Mixtures  

NASA Astrophysics Data System (ADS)

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.

Azar, Amin S.; Ås, Sigmund K.; Akselsen, Odd M.

2013-03-01

383

K-distribution models for gas mixtures in hypersonic nonequilibrium flows  

NASA Astrophysics Data System (ADS)

Calculation of nonequilibrium radiation field in plasmas around a spacecraft entering into an atmosphere at hypersonic velocities is a very complicated and computationally expensive task. The objective of this Dissertation is to collect state-of-the art spectroscopic data for the evaluation of spectral absorption and emission coefficients of atomic and molecular gases, develop efficient and accurate spectral models and databases, and study the effect of radiation on wall heat loads and flowfield around the spacecraft. The most accurate simulation of radiative transport in the shock layer requires calculating the gas properties at a large number of wavelengths and solving the Radiative Transfer Equation (RTE) in a line-by-line (LBL) fashion, which is prohibitively expensive for coupled simulations. A number of k-distribution based spectral models are developed for atomic lines, continuum and molecular bands that allow efficient evaluation of radiative properties and heat loads in hypersonic shock layer plasma. Molecular radiation poses very different challenges than atomic radiation. A molecular spectrum is governed by simultaneous electronic, vibrational and rotational transitions, making the spectrum very strongly dependent on wavelength. In contrast to an atomic spectrum, where line wings play a major role in heat transfer, most of the heat transfer in molecular spectra occurs near line centers. As the first step, k-distribution models are developed separately for atomic and molecular species, taking advantage of the fact that in the Earth's atmosphere the radiative field is dominated by atomic species (N and O) and in Titan's and Mars' atmospheres molecular bands of CN and CO are dominant. There are a number of practical applications where both atomic and molecular species are present, for example, the vacuum-ultra-violet spectrum during Earth's reentry conditions is marked by emission from atomic bound-bound lines and continuum and simultaneous absorption by strong bands of N2. For such cases, a new model is developed for the treatment of gas mixtures containing atomic lines, continuum and molecular bands. Full-spectrum k-distribution (FSK) method provides very accurate results compared to those obtained from the exact line-by-line method. For cases involving more extreme gradients in species concentrations and temperature, full-spectrum k-distribution model is relatively less accurate, and the method is refined by dividing the spectrum into a number of groups or scales, leading to the development of multi-scale models. The detailed methodology of splitting the gas mixture into scales is presented. To utilize the full potential of the k-distribution methods, pre-calculated values of k-distributions are stored in databases, which can later be interpolated at local flow conditions. Accurate and compact part-spectrum k-distribution databases are developed for atomic species and molecular bands. These databases allow users to calculate desired full-spectrum k-distributions through look-up and interpolation. Application of the new spectral models and databases to shock layer plasma radiation is demonstrated by solving the radiative transfer equation along typical one-dimensional flowfields in Earth's, Titan's and Mars' atmospheres. The k-distribution methods are vastly more efficient than the line-by-line method. The efficiency of the method is compared with the line-by-line method by measuring computational times for a number of test problems, showing typical reduction in computational time by a factor of more than 500 for property evaluation and a factor of about 32,000 for the solution of the RTE. A large percentage of radiative energy emitted in the shock-layer is likely to escape the region, resulting in cooling of the shock layer. This may change the flow parameters in the flowfield and, in turn, can affect radiative as well as convective heat loads. A new flow solver is constructed to simulate coupled hypersonic flow-radiation over a reentry vehicle. The flow solver employs a number of existing schemes and tools av

Bansal, Ankit

384

Measurements of the first Townsend coefficient in gas mixtures at high fields  

Microsoft Academic Search

Summary form only. In order to understand the operating characteristics of drift chambers operating in proportional and streamer regimes, and to obtain better localization accuracy, the authors have measured the first Townsend coefficient ?, for some argon-based mixtures, namely, with methane, ethane, isobutane, di-methylether, carbon-dioxide, and CF4, and for similar helium-based mixtures, as a function of high field, at various

F. Sauli; A. Sharma

1992-01-01

385

The effects of the use of different shielding gas mixtures in laser welding of metals  

Microsoft Academic Search

The paper makes use of the solution of the system of Saha equations derived for any mixture of ionized monatomic gases. This solution is specifically applied to the case of two-component mixtures of the gases used as shields in the process of laser welding, namely Ar plus He, Ar plus O2, Ar plus N2 and Ar plus H2. The number

M. H. Glowacki

1995-01-01

386

Effect of hydrogen ratio on plasma parameters of N{sub 2}-H{sub 2} gas mixture glow discharge  

SciTech Connect

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.

El-Brulsy, R. A.; Abd Al-Halim, M. A.; Abu-Hashem, A. [Benha University, Physics Department, Faculty of Science (Egypt); Rashed, U. M. [Alazhar University, Physics Department, Faculty of Science (Egypt); Hassouba, M. A. [Benha University, Physics Department, Faculty of Science (Egypt)

2012-05-15

387

Reduced xenon diffusion for quantitative lung study--the role of SF(6)  

NASA Technical Reports Server (NTRS)

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.

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

388

The XENON dark matter experiment , E. Aprileb  

E-print Network

The XENON dark matter experiment T. Shutta , E. Aprileb , E. Baltzb , K. Gibonib , P. Majewskib , M Laboratory, Livermore, CA 94550 We report on progress of the XENON collaboration, which is developing a liquid xenon time projection chamber technology for use in a very-large-mass dark matter experiment

McDonald, Kirk

389

Breakdown mechanism in C3F8\\/CO2 gas mixture under non-uniform field on the basis of partial discharge properties  

Microsoft Academic Search

This paper investigates simultaneous measurements of partial discharge (PD) current and the corresponding light emission phenomena of C3F8\\/CO2 gas mixture under a non-uniform field with AC high voltage application in order to discuss the PD properties and breakdown mechanism of new gaseous dielectrics as SF6 substitutes. Perfluoro carbon (PFC) gas mixture is a possible candidate as SF6 substitute because it

Masayuki Hikita; Shinya Ohtsuka; Shigemitsu Okabe; Genyo Ueta

2009-01-01

390

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Pulsed electron-beam-sustained discharge in oxygen-containing gas mixtures: electrical characteristics, spectroscopy,and singlet oxygen yield  

Microsoft Academic Search

The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume (~18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition

Nikolai P. Vagin; Andrei A. Ionin; Yu M. Klimachev; A. A. Kotkov; Igor'V. Kochetov; A. P. Napartovich; Yu P. Podmar'kov; L. V. Seleznev; D. V. Sinitsyn; M. P. Frolov; G. D. Hager; Nikolai N. Yuryshev

2004-01-01

391

Relaxation of Spin Polarisation of Sodium Vapor due to Sodium-Xenon Van Der Waals Molecules.  

NASA Astrophysics Data System (ADS)

We have studied the relaxation of ground state sodium spin polarisation in xenon gas as a function of magnetic field in the presence of nitrogen and helium as buffer gases. The dependence of the sodium spin relaxation on magnetic. field and on the pressure of helium gas shows that the relaxation. mostly takes place in loosely bound sodium-xenon van der Waals. molecules. It is observed that the spin orbit interaction is the. dominant mechanism for the relaxation of sodium spin polarisation. We report the first measurement of the average spin orbit coupling. constant (gamma) (H/2PI)('-1) = 0.9 MHz in sodium -xenon molecule. The life time(' ). of the molecules is found to be. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). in cells containing 2 torr of xenon, 10 torr of nitrogen and a helium pressure P(He) ranging from 24 to 200 torr.

Suleman, Badar

392

Detection of brown adipose tissue and thermogenic activity in mice by hyperpolarized xenon MRI.  

PubMed

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

Branca, Rosa Tamara; He, Ting; Zhang, Le; Floyd, Carlos S; Freeman, Matthew; White, Christian; Burant, Alex

2014-12-16

393

Removal of particle matter from dust-vapor-gas mixture in condenser with inclined tubes  

NASA Astrophysics Data System (ADS)

The article presents results of the research of particulate matter and droplets removal on inclined tubes of the flue gas cleaning condenser in the process of vapor condensation of vapor-and-gas emissions from kraft pulp production.

Romanova, L. V.; Gogonin, I. I.

2012-03-01

394

Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with neon  

NASA Astrophysics Data System (ADS)

Results are presented from studies of the optical characteristics and parameters of plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with neon—the working medium of a non-coaxial exciplex gas-discharge emitter. The electron energy distribution function, the transport characteristics, the specific power losses for electron processes, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering by the working mixture components are determined as functions of the reduced electric field. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules is found to be 1.6 × 10-14 m3/s for a reduced electric field of E/ N = 15 Td, at which the maximum emission intensity in the blue-green spectral region (?max = 502 nm) was observed in this experiment.

Malinina, A. A.; Malinin, A. N.

2013-12-01

395

Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with neon  

SciTech Connect

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 (?{sub max} = 502 nm) was observed in this experiment.

Malinina, A. A., E-mail: alexandr_malinin@rambler.ru; Malinin, A. N. [Uzhhorod National University (Ukraine)

2013-12-15

396

Improved Resolution of Hydrocarbon Structures and Constitutional Isomers in Complex Mixtures Using Gas Chromatography-Vacuum  

E-print Network

Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry Gabriel Isaacman,*, Kevin R. Wilson, Arthur W be confidently identified using traditional gas chromatography/mass spectrometry (GC/MS) techniques. This work, a variety of liquid and gas chromatography (LC and GC) techniques have been used with great success

Cohen, Ronald C.

397

Gas-liquid-liquid equilibria in mixtures of water, light gases, and hydrocarbons  

SciTech Connect

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.

Chao, K.C.

1990-01-01

398

Effect of flow velocity and temperature on ignition characteristics in laser ignition of natural gas and air mixtures  

NASA Astrophysics Data System (ADS)

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.

Griffiths, J.; Riley, M. J. W.; Borman, A.; Dowding, C.; Kirk, A.; Bickerton, R.

2015-03-01

399

A measurement of the relativistic rise in xenon-filled ionisation chambers for cosmic ray iron  

NASA Technical Reports Server (NTRS)

The relativistic rise of ionization in a pair of xenon-filled pulse ion chambers was measured for primary iron nuclei during a recent balloon flight. Energy calibration over the range 21.5-60 GeV/n was made with a Freon-12 gas Cerenkov detector. This allowed a comparison with recent calculations of the relativistic rise in xenon counters and an estimate of the ion chamber resolution above 21.5 GeV/n to be made.

Gregory, J. C.; Parnell, T. A.

1980-01-01

400

Latest results from XENON100 data  

E-print Network

XENON100 is the current phase of the XENON dark matter program, which aims for the direct detection of WIMPs with liquid xenon time-projection chambers. We present the status of the experiment after 224.6 live days taken in 2011 and 2012 during which the detector successfully improved in terms of more calibration data, higher xenon purity, lower threshold and better background removal. The analysis has yielded no evidence for dark matter interactions. The status of the next generation XENON1T detector will be briefly described.

Luca Scotto Lavina; for the XENON100 Collaboration

2013-05-01

401

Pulsed electron-beam-sustained discharge in oxygen-containing gas mixtures: electrical characteristics, spectroscopy,and singlet oxygen yield  

SciTech Connect

The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume ({approx}18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition of small amounts ({approx}1%-10%) of carbon monoxide or hydrogen to oxygen or its mixtures with inert gases considerably improves the stability of the discharge, while the specific energy contribution W increases by more then an order of magnitude, achieving {approx}6.5 kJ L{sup -1} atm{sup -1} per molecular component of the gas mixture. A part of the energy supplied to the EBSD is spent to excite vibrational levels of molecular additives. This was demonstrated experimentally by the initiation of a CO laser based on the O{sub 2} : Ar : CO = 1 : 1 : 0.1 mixture. Experimental results on spectroscopy of the excited electronic states O{sub 2}(a{sup 1{Delta}}{sub g}) and O{sub 2}(b{sup 1{Sigma}}{sub g}{sup +}), of oxygen formed in the EBSD are presented. A technique was worked out for measuring the concentration of singlet oxygen in the O{sub 2}(a{sup 1{Delta}}{sub g}) state in the afterglow of the pulsed EBSD by comparing with the radiation intensity of singlet oxygen of a given concentration produced in a chemical generator. Preliminary measurements of the singlet-oxygen yield in the EBSD show that its value {approx}3% for W {approx} 1.0 kJ L{sup -1} atm{sup -1} is in agreement with the theoretical estimate. Theoretical calculations performed for W {approx} 6.5 kJ L{sup -1} atm{sup -1} at a fixed temperature show that the singlet-oxygen yield may be {approx}20%, which is higher than the value required to achieve the lasing threshold in an oxygen-iodine laser at room temperature. (laser applications and other topics in quantum electronics)

Vagin, Nikolai P; Ionin, Andrei A; Klimachev, Yu M; Kotkov, A A; Podmar'kov, Yu P; Seleznev, L V; Sinitsyn, D V; Frolov, M P; Yuryshev, Nikolai N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Kochetov, Igor' V; Napartovich, A P [State Research Center of Russian Federation 'Troitsk Institute for Innovation and Fusion Research', Troitsk, Moscow Region (Russian Federation); Hager, G D [Air Force Research Laboratory, Albuquerque, NM (United States)

2004-09-30

402

Coherent and spontaneous Rayleigh-Brillouin scattering in atomic and molecular gases and gas mixtures  

SciTech Connect

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.

Vieitez, M. O.; Duijn, E. J. van; Ubachs, W. [Laser Centre, Vrije Universiteit, De Boelelaan 1081, NL-1081 HV Amsterdam (Netherlands); Witschas, B. [Deutsches Zentrum fuer Luft- und Raumfahrt DLR, Institut fuer Physik der Atmosphaere, Oberpfaffenhofen (Germany); Meijer, A.; Wijn, A. S. de; Dam, N. J. [Institute of Molecules and Materials, Applied Molecular Physics, Radboud University, NL-6500 HC Nijmegen (Netherlands); Water, W. van de [Physics Department, Eindhoven University of Technology, Postbus 513, NL-5600 MB Eindhoven (Netherlands)

2010-10-15

403

A pressure-shift study of electron scattering in dense hydrogen—argon gas mixtures  

NASA Astrophysics Data System (ADS)

Rydberg absorption spectra of methyl iodide, CH 3I, in hydrogen—argon binary mixtures of density (2.16-3.14) × 10 20 cm -3 are reported. The Rydberg energy shifts, normalized to a total density of 1 × 10 21 cm -3, vary linearly with the mole fraction of the binary mixture. Reservations concerning this linearity are elaborated. The relationship of scattering lengths to cross sections for binary scatterers is discussed: cross sections, as obtained from mobility measurements, are additive for binaries whereas, for pressure-shift measurements, it is scattering lengths which are additive.

Asaf, U.; Felps, S.; Rupnik, K.; McGlynn, S. P.

1993-09-01

404

Sound waves in monodisperse gas-particle or vapour-droplet mixtures  

Microsoft Academic Search

A brief review of the relevant papers and an examination of the current status of research in the field of the acoustics of gas-particle suspensions are given. Nonstationary momentum, mass and energy transfer processes between a gas (vapor) and dispersed particles (droplets) under high-frequency acoustic perturbations are considered. A comparative evaluation of characteristic times and temperature differences for gas-particle and

N. A. Gumerov; A. I. Ivandaev; R. I. Nigmatulin

1988-01-01

405

Thermodynamic and molecular properties of gas hydrates from mixtures containing methane, argon, and krypton  

Microsoft Academic Search

Because hydrate formation in pipelines, processing operations, and reservoirs is generally undesirable, studies of gas-hydrate thermodynamics, particularly examinations of conditions where a second hydrate phase or a hydrocarbon-rich phase exists in addition to the water, hydrate, and gas phases, are important to the natural gas industry. In this study, analysts used experimental methane-krypton and methane-argon hydrate data to generate chemical-potential,

G. D. Holder; G. Corbin; K. D. Papadopoulos

1980-01-01

406

The Chemistry of Volcanic Gases 1. Collection and Analysis of Equilibrium Mixtures by Gas Chromatography  

Microsoft Academic Search

An adsorption method for the collection of volcanic gases is described. Samples were collected in evacuated tubes containing a column o.f activated silica gel. These samples were found to be more representative of the gases collected from artificial test mixtures than samples collected by usual methods. The adsorption method is therefore concluded to be a more satisfactory technique for sampling

John J. Naughton; Emerson F. Heald; I. Lynus Barnes

1963-01-01

407

Nanosecond gas discharge ignition of H 2 ? and CH 4 ? containing mixtures  

Microsoft Academic Search

An analysis of the ignition of H2? and CH4? containing mixtures at high temperatures under the action of a nanosecond high-voltage discharge has been performed both numerically and experimentally for a wide range of parameters. A comparison of the equilibrium and nonequilibrium excitation was performed. The preliminary numerical analysis of ignition efficiency helped to plan experimental investigations of the initiation

S. A. Bozhenkov; S. M. Starikovskaia; A. Yu. Starikovskii

2003-01-01

408

Inlet flow behind mixers for gas-liquid mixtures in horizontal pipes  

Microsoft Academic Search

Systematic measurements of the variation of static pressure with distance from the mixer have shown that for air-water mixtures, the manner of bringing together the two phases in the mixer does, indeed, have an effect on the pressure variation in the inlet region, but not on the inlet length itself. The inlet length is chiefly determined by the difference between

H.-D. Clemen; J. M. Chawla

1977-01-01

409

High Pressure XENON Gamma-Ray Spectrometers for Field Use  

SciTech Connect

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.

David K. Wehe; Zong He; Glenn K. Knoll

2004-02-16

410

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)

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.

Wiens, Roger C.; Burnett, D. S.; Neugebauer, M.; Pepin, R. O.

1992-01-01

411

Characteristics of a cylindrical collector mirror for laser-produced xenon plasma soft X-rays and improvement of mirror lifetime by buffer gas  

SciTech Connect

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.

Inoue, Tomoaki; Mochizuki, Takayasu; Miyamoto, Shuji; Masuda, Kazuya; Amano, Sho; Kanda, Kazuhiro [Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Ako-gun, Hyogo 678-1205 (Japan)

2012-12-15

412

Characteristics of a cylindrical collector mirror for laser-produced xenon plasma soft X-rays and improvement of mirror lifetime by buffer gas.  

PubMed

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(2) at the center of the irradiation zone. Thus, the irradiation intensity was improved by approximately 27 times when compared to that of 47 ?J/cm(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 ?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. PMID:23277975

Inoue, Tomoaki; Mochizuki, Takayasu; Miyamoto, Shuji; Masuda, Kazuya; Amano, Sho; Kanda, Kazuhiro

2012-12-01

413

Resist Pattern Reformation by Reactive Ion Etching with Ar+CH4 Gas Mixture and Its Application  

NASA Astrophysics Data System (ADS)

Resist sputter-etching characteristics and deposited film morphology on a fine pattern are investigated in this paper. An Ar+CH4 gas mixture is adopted as the etching gas to combine the sputter-etching with the hydrocarbon film deposition for the reformation of resist pattern. The resist pattern is reformed in this way with no reduction in the resist pattern width. This method forms a high resistance layer on the resist surface, improving dry etching durability of the resist. This method is then applied to a two-layer resist pattern formation process and it is found that submicron pattern can be easily obtained in two-layer (FBM/PMMA) resist.

Watanabe, Iwao

1984-04-01

414

A numerical program for steady-state flow of magma-gas mixtures through vertical eruptive conduits  

USGS Publications Warehouse

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.

Mastin, Larry G.; Ghiorso, Mark S.

2000-01-01

415

Pulse Shape in 2-Phase Xenon Detectors  

NASA Astrophysics Data System (ADS)

Understanding the shape and size of the primary (S1) and secondary (S2) scintillation pulses in noble elements is crucial for discriminating between different particle interactions. Monte Carlo results from NEST (the Noble Element Simulation Technique) will be presented which match the available data from liquid xenon on the dependence of the recombination time, which is a critical piece of the S1 pulse timing structure, on dE/dx, interaction type, and electric field magnitude. In addition, a model for the S2 pulse shape and the dependence of its width on the depth of an interaction in a detector will be presented which takes into account drift speed, the single/triplet time constants, diffusion, thermal electron trapping at a liquid-gas interface, and other effects.

Mock, Jeremy

2013-04-01

416

Investigations of Wafer Scale Etching with Xenon Difluoride  

Microsoft Academic Search

A good and uniform bulk silicon wafer etching method can be applied to the wafer thinning process in MEMS and 3D applications. In this study, the use of a Xenon Difluoride (XeF2) gas-phase etching system, operating at room temperature, has been investigated for bulk silicon wafer thinning. We investigated the Si-wafer surface morphology and profile following each XeF2 etching process

K. N. Chen; N. Hoivik; C. Y. Lin; A. Young; M. Ieong; G. Shahidi

2006-01-01

417

Quench gases for xenon- (and krypton-) filled proportional counters  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

418

Gas mixture circulation system in lasers using a high-frequency barrier discharge  

SciTech Connect

Electrohydrodynamic flow in gas for a high-frequency barrier discharge distributed over the surface of a dielectric was investigated. An electric-discharge laser circulation system with a gas flow rate higher than 15 L s{sup -1} was proposed.

Moshkunov, S I; Nebogatkin, S V; Rebrov, I E; Khomich, V Yu; Yamshchikov, V A [Institute of Electrophysics and Electric Power, Russian Academy of Sciences, S.-Petersburg (Russian Federation)

2011-12-31

419

Separation of Carbon Dioxide from Natural Gas Mixtures through Polymeric Membranes—A Review  

Microsoft Academic Search

Various technologies are now available to design engineers to condition raw natural gas to pipeline quality. Conditioning of natural gas involves the removal of acid gases like CO2 and H2S, besides water vapor. Among different separation methods available, membrane technology has emerged to be a viable and valuable option over conventional techniques like amine absorption, in view of its advantages

S. Sridhar; B. Smitha; T. M. Aminabhavi

2007-01-01

420

The adsorption of argon, krypton and xenon on activated charcoal  

SciTech Connect

Charcoal adsorption beds are commonly used to remove radioactive noble gases from contaminated gas streams. The design of such beds requires the adsorption coefficient for the noble gas. Here an extension of the Dubinin-Radushkevich theory of adsorption is developed to correlate the effects of temperature, pressure, concentration, and carrier gas on the adsorption coefficients of krypton, xenon, and argon on activated carbon. This model is validated with previously published adsorption measurements. It accurately predicts the equilibrium adsorption coefficient at any temperature and pressure if the potential energies of adsorption, the micropore volume, and the van der Waals constants of the gases are known. 18 refs., 4 figs.

Underhill, D.W. [Univ. of South Carolina, Columbia, SC (United States)

1996-08-01

421

Fission Xenon on Mars  

NASA Technical Reports Server (NTRS)

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.

Mathew, K. J.; Marti, K.; Marty, B.

2002-01-01

422

Reacting gas mixtures in the state-to-state approach: The chemical reaction rates  

NASA Astrophysics Data System (ADS)

In this work chemically reacting mixtures of viscous flows are analyzed within the framework of Boltzmann equation. By applying a modified Chapman-Enskog method to the system of Boltzmann equations general expressions for the rates of chemical reactions and vibrational energy transitions are determined as functions of two thermodynamic forces: the velocity divergence and the affinity. As an application chemically reacting mixtures of N2 across a shock wave are studied, where the first lowest vibrational states are taken into account. Here we consider only the contributions from the first four single quantum vibrational-translational energy transitions. It is shown that the contribution to the chemical reaction rate related to the affinity is much larger than that of the velocity divergence.

Kustova, Elena V.; Kremer, Gilberto M.

2014-12-01

423

Separation of a Five-Component Gas Mixture by Pressure Swing Adsorption  

Microsoft Academic Search

Bulk separation of a five-component mixture simulating coal gasification products was performed by pressure swing adsorption (PSA) using activated carbon. The PSA cycle consisted of four commercially used steps: (I) pressurization with H2, (II) adsorption, (III) blowdown, and (IV) evacuation. Using this cycle, four products were obtained with a single PSA unit: H2 (over 99.7% purity), CO, CH4, and acid

Peiling Cen; Ralph T. Yang

1985-01-01

424

On inelastic reactive collisions in kinetic theory of chemically reacting gas mixtures  

Microsoft Academic Search

A kinetic theory for a simple reversible reaction–characterized by a binary mixture of ideal gases whose constituents denoted by A and B undergo a reaction of the type A+A?B+B–is developed by considering the reactive collisions as inelastic ones. The geometry of the collision is taken into account in the line-of-centers differential cross section by allowing that a chemical reaction may

Gilberto M. Kremer; Adriano W. Silva; Giselle M. Alves

2010-01-01

425

Effect of binary mixtures of surfactants on horizontal gas–liquid flow with low liquid loading  

Microsoft Academic Search

The interaction between anionic and zwitterionic surfactant (sodium dodecyl sulphate\\/dodecyl betaine) brings about the synergism in the surface tension reduction and the micelle formation. The binary mixtures of surfactants were added to air–water flow with low liquid loading in a horizontal 50.8 mm pipe. Two concentrations with a 6:4 molar ratio of zwitterionic to anionic surfactant were tested to investigate their

Yi-ping Liu; Hua Zhang; Shu-hua Wang; Jing Wang

2009-01-01

426

Gas Dynamic Features of Self Ignition of Non Diluted Fuel\\/Air Mixtures at High Pressure  

Microsoft Academic Search

– The self ignition of several non diluted fuel\\/air mixtures at high pressureis studied. Hydrogen,rsc-ocrane and n-heptane have been used as fuels. Experimentshave been performedusing the shock tube technique. Various observation methods, such as recording of pressure and of light band emission and shadow cinematography have been applied. The type of self ignition 35 well as the ignition delay times

R. BLUMENTHAL; K. FIEWEGER; K. H. KOMP; G. ADOMEIT

1997-01-01

427

Gas Dynamic Features of Self Ignition of Non Diluted Fuel\\/Air Mixtures at High Pressure  

Microsoft Academic Search

The self ignition of several non diluted fuel\\/air mixtures at high pressure is studied. Hydrogen, iso-octane and n-heptane have been used as fuels. Experiments have been performed using the shock tube technique. Various observation methods, such as recording of pressure and of light band emission and shadow cinematography have been applied. The type of self ignition as well as the

R. BLUMENTHAL; K. FIEWEGER; K. H. KOMP; G. ADOMEIT

1996-01-01

428

Test Chamber for Optimizing a High Pressure Xenon Neutrinoless Double Beta Decay Detector  

NASA Astrophysics Data System (ADS)

The NEXT experiment is designed to search for neutrinoless double beta decay in high pressure xenon gas; the gas is enriched with ^136Xe which is a double beta decay candidate emitter. It is currently in the research and development phase and is scheduled to be operating in Canfranc Underground Laboratory in Huesca Spain within the next 5 years. High pressure xenon gas is chosen because of its excellent energy resolution and the ability to observe tracks. Observation of the track end points will provide excellent background rejection. The design and principle of a test chamber used to optimize the detector design will be discussed.

Robert, Paul

2009-10-01

429

Increase of passenger car engine efficiency with low engine-out emissions using hydrogen–natural gas mixtures: A thermodynamic analysis  

Microsoft Academic Search

In this study a state of the art passenger car natural gas engine was optimised for hydrogen natural gas mixtures and high exhaust gas recirculation (EGR) rates in the part load domain. With optimal combinations of spark timing (ST) and EGR rate the achievements are significant efficiency increase with substantially lower engine-out NOx while total unburned hydrocarbons or CO-engine-out emissions

P. Dimopoulos; C. Rechsteiner; P. Soltic; C. Laemmle; K. Boulouchos

2007-01-01

430

SAFE OPERATION OF NATURAL GAS APPLIANCES FUELED WITH HYDROGEN\\/NATURAL GAS MIXTURES (PROGRESS OBTAINED IN THE NATURALHY-PROJECT)  

Microsoft Academic Search

Considering the transition towards the hydrogen economy, dependent on hydrogen penetration scenario, the cost of a new hydrogen pipeline infrastructure in Europe may amount to several thousands of billions of EURO's. Therefore, the examination of the potential contribution of the existing natural gas assets is a practical and logical first step. As the physical and chemical properties of hydrogen differ

De Vries; O. Florisson; G. C. Tiekstra

431

Resolving the Unresolved Complex Mixtures of Hydrothermal Petroleum Using Comprehensive Two-Dimensional Gas Chromatography - Time of Flight Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Within hydrothermal systems sedimentary organic matter can be altered by high temperature fluids resulting in the generation of petroleum. These hydrothermal petroleums are compositionally similar to conventional, basin- formed petroleum, with the exception that they often contain substantial mixtures of coeluting organic compounds, which are difficult to resolve by traditional gas chromatographic methods. The coelution of these compounds produces a rapidly rising baseline in gas chromatogram that is referred to as an unresolved complex mixture (UCM). Little is known about these UCMs or why and how they form. In this study we analyzed the apolar fractions of four hydrothermal petroleum samples from the Middle Valley, Juan de Fuca Ridge and Escanaba Trough, Gorda Ridge in the NE Pacific Ocean and the Guaymus Basin, Gulf of California using comprehensive two-dimensional gas chromatography-Time of Flight Mass Spectrometry (GC×GC-ToFMS). The GC×GC-ToFMS chromatograms of these samples elucidate two hydrocarbon subsets. The first subset consists of commonly defined hydrocarbon series such as n-alkanes, alkylcyclohexanes, alkylbenzenes, naphthalenes, tricylic terpanes, steranes, and hopanes. The second subset is dominated by compounds forming the UCM. These compounds form a continuous series of configurational isomers that become increasingly aromatic at higher molecular weights. The UCMs of the hydrothermal petroleum samples vary as a function of the relative intensity, number, and molecular weight range of the contributing configurational isomers. The subset appears to represent areas of mass gain that overprint the first subset in the GC×GC-ToFMS chromatogram. This gain likely reflects an exogenous input or the accumulation of primary organic matter that underwent extensive dehydrogenation and dealkylation. Variation between the second hydrocarbon sample subsets is likely caused by different thermal gradients within the pyrolytic regimes, gaseous solubilization, hydrodynamic alteration from multi-component fluids, and post-depositional alteration from biodegradation and water-washing.

Ventura, G. T.; Reddy, C. M.; Simoneit, B. R.; Nelson, R. K.

2007-12-01

432

Xenon preconditioning: molecular mechanisms and biological effects  

PubMed Central

Xenon is one of noble gases and has been recognized as an anesthetic for more than 50?years. Xenon possesses many of the characteristics of an ideal anesthetic, but it is not widely applied in clinical practice mainly because of its high cost. In recent years, numerous studies have demonstrated that xenon as an anesthetic can exert neuroprotective and cardioprotective effects in different models. Moreover, xenon has been applied in the preconditioning, and the neuroprotective and cardioprotective effects of xenon preconditioning have been investigated in a lot of studies in which some mechanisms related to these protections are proposed. In this review, we summarized these mechanisms and the biological effects of xenon preconditioning. PMID:23305274

2013-01-01

433

Conversion of synthesis gas to hydrocarbon mixtures utilizing a dual catalyst bed  

SciTech Connect

A gaseous mixture of carbon monoxide and hydrogen is passed in contact over a first catalyst bed comprising an iron or cobalt containing fischer-tropsch catalyst in combination with a crystalline aluminosilicate of the class of crystalline zeolite represented by ZSM-5 so as to obtain a liquid hydrocarbon product having a boiling range of less than 400/sup 0/ F at a 90% overhead and being a predominantly olefinic product. The total products from said contact including said liquid hydrocarbon product are then converted over a second catalyst bed containing HZSM-5 to obtain a highly aromatic product, i.e., greater than 20 weight percent.

Brennan, J.A.; Caesar, P.D.; Ciric, J.; Garwood, W.E.

1981-12-08

434

Device for two-dimensional gas-phase separation and characterization of ion mixtures  

DOEpatents

The present invention relates to a device for separation and characterization of gas-phase ions. The device incorporates an ion source, a field asymmetric waveform ion mobility spectrometry (FAIMS) analyzer, an ion mobility spectrometry (IMS) drift tube, and an ion detector. In one aspect of the invention, FAIMS operating voltages are electrically floated on top of the IMS drift voltage. In the other aspect, the FAIMS/IMS interface is implemented employing an electrodynamic ion funnel, including in particular an hourglass ion funnel. The present invention improves the efficiency (peak capacity) and sensitivity of gas-phase separations; the online FAIMS/IMS coupling creates a fundamentally novel two-dimensional gas-phase separation technology with high peak capacity, specificity, and exceptional throughput.

Tang, Keqi (Richland, WA); Shvartsburg, Alexandre A. (Richland, WA); Smith, Richard D. (Richland, WA)

2006-12-12

435

A program for calculating expansion-tube flow quantities for real-gas mixtures and comparison with experimental results  

NASA Technical Reports Server (NTRS)

A computer program written in FORTRAN 4 language is presented which determines expansion-tube flow quantities for real test gases CO2 N2, O2, Ar, He, and H2, or mixtures of these gases, in thermochemical equilibrium. The effects of dissociation and first and second ionization are included. Flow quantities behind the incident shock into the quiescent test gas are determined from the pressure and temperature of the quiescent test gas in conjunction with: (1) incident-shock velocity, (2) static pressure immediately behind the incident shock, or (3) pressure and temperature of the driver gas (imperfect hydrogen or helium). The effect of the possible existence of a shock reflection at the secondary diaphragm of the expansion tube is included. Expansion-tube test-section flow conditions are obtained by performing an isentropic unsteady expansion from the conditions behind the incident shock or reflected shock to either the test-region velocity or the static pressure. Both a thermochemical-equilibrium expansion and a frozen expansion are included. Flow conditions immediately behind the bow shock of a model positioned at the test section are also determined. Results from the program are compared with preliminary experimental data obtained in the Langley 6-inch expansion tube.

Miller, C. G., III

1972-01-01

436

Analysis of the insulation characteristics of CF3I gas mixtures with Ar, Xe, He, N2, and CO2 using Boltzmann equation method  

NASA Astrophysics Data System (ADS)

The present study is devoted to the calculation of electron swarm parameters, including the reduced effective ionization coefficient, electron mean energy, and electron drift velocity, for the gas mixtures of CF3I with Ar, Xe, He, N2, and CO2. These data are computed by employing the Boltzmann equation method with two-term approximation in the condition of steady-state Townsend (SST) discharge. For the purpose of evaluating the insulation strength of CF3I gas mixtures, values of the limiting field strength (E/N)lim for which the ionization exactly balances the electron attachment are determined from the variation curves of (? - ?)/N. The results indicate that mixtures of CF3I-N2 present the greatest insulation strength among all the combinations for CF3I content varied from 20 to 90%. Furthermore, the gas mixture with 70% CF3I can achieve a very similar dielectric strength to that of SF6. The concerned liquefaction issues are also taken into account to fully assess the possibility of applying CF3I gas mixtures in power equipment as an insulation medium.

Deng, Yunkun; Xiao, Dengming

2014-09-01

437

Luminescence characteristics of Xe{sub 2}Cl excimer molecules under pumping the dense Xe-CCl{sub 4} gas mixtures with a pulsed electron beam  

SciTech Connect

Temporal and spectral characteristics of the luminescence of dense Xe-CCl{sub 4} gas mixtures of different composition, excited by a 5-ns pulsed electron beam, were measured. The energy of the electrons amounted to 150 keV and the electron beam current pulse amplitude was 5 A. The gas mixtures were used containing Xe (38-700 Torr) and CCl{sub 4} (0.03-0.3 Torr). The studies were performed within the wavelength range 200-1200 nm using a MAYA-2000Pro diffraction grating spectrometer and a RIGOL DS 5022 ME fast digital oscilloscope. The luminescence lifetimes of the excimer molecules XeCl* (band with {lambda}{sub max} = 308 nm) and Xe{sub 2}Cl* (band with {lambda}{sub max} = 486 nm) were measured, as well as the constants of quenching by the components of the gas mixture for Xe{sub 2}Cl* molecules. A model of plasma-chemical processes for dense Xe-CCl{sub 4} gas mixtures with a very low content of the CCl{sub 4} donor is proposed. It is shown that in such 'poor' mixtures Xe{sub 2}Cl* molecules are mainly produced as a result of recombination of the Xe{sub 2}{sup +} and Cl{sup -} ions. (active media)

Mis'kevich, A I; Jinbo, Guo [National Research Nuclear University 'Moscow Engineering Physics Institute', Moscow (Russian Federation)] [National Research Nuclear University 'Moscow Engineering Physics Institute', Moscow (Russian Federation)

2013-05-31

438

Theoretical study of xenon adsorption in UO2 nanoporous matrices  

NASA Astrophysics Data System (ADS)

We present a theoretical study of xenon incorporation in UO2 nanocavities, by means of Grand Canonical Monte Carlo calculations based on semi-empirical potentials. We first characterize the reconstruction of the matrix around an empty cavity which leads to a stoechiometry change from UO2 to UO in this region. Then, we determine xenon adsorption isotherms which exhibit an abrupt transition from a dilute phase to a dense one and an increase in the density of the latter phase as a function of temperature. This last result is attributed to a vibrational entropy effect by means of a mean field analysis. Finally, the pressure calculation inside the bubble proves the limitations of the usual mesoscopic models based on gas state behaviour.

Colbert, Mehdi; Tréglia, Guy; Ribeiro, Fabienne

2014-12-01

439

Theoretical study of xenon adsorption in UO2 nanoporous matrices.  

PubMed

We present a theoretical study of xenon incorporation in UO2 nanocavities, by means of Grand Canonical Monte Carlo calculations based on semi-empirical potentials. We first characterize the reconstruction of the matrix around an empty cavity which leads to a stoechiometry change from UO2 to UO in this region. Then, we determine xenon adsorption isotherms which exhibit an abrupt transition from a dilute phase to a dense one and an increase in the density of the latter phase as a function of temperature. This last result is attributed to a vibrational entropy effect by means of a mean field analysis. Finally, the pressure calculation inside the bubble proves the limitations of the usual mesoscopic models based on gas state behaviour. PMID:25388362

Colbert, Mehdi; Tréglia, Guy; Ribeiro, Fabienne

2014-12-01

440

Internal structure of shock waves in disparate mass mixtures  

NASA Technical Reports Server (NTRS)

The detailed flow structure of a normal shock wave for a gas mixture is investigated using the direct-simulation Monte Carlo method. A variable diameter hard-sphere (VDHS) model is employed to investigate the effect of different viscosity temperature exponents (VTE) for each species in a gas mixture. Special attention is paid to the irregular behavior in the density profiles which was previously observed in a helium-xenon experiment. It is shown that the VTE can have substantial effects in the prediction of the structure of shock waves. The variable hard-sphere model of Bird shows good agreement, but with some limitations, with the experimental data if a common VTE is chosen properly for each case. The VDHS model shows better agreement with the experimental data without adjusting the VTE. The irregular behavior of the light-gas component in shock waves of disparate mass mixtures is observed not only in the density profile, but also in the parallel temperature profile. The strength of the shock wave, the type of molecular interactions, and the mole fraction of heavy species have substantial effects on the existence and structure of the irregularities.

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

1992-01-01

441

Oxygen/ozone as a medical gas mixture. A critical evaluation of the various methods clarifies positive and negative aspects  

PubMed Central

Besides oxygen, several other gases such as NO, CO, H2, H2S, Xe and O3 have come to age over the past few years. With regards to O3, its mechanisms of action in medicine have been clarified during the last two decades so that now a comprehensive framework for understanding and recommending ozone therapy in various pathologies is available. O3 used within the determined therapeutic window is absolutely safe and more effective than golden standard medications in numerous pathologies, like vascular diseases. However, ozone therapy is mostly in practitioners' hands and some recent developments for increasing cost effectiveness and speed of treatment are neither standardized, nor evaluated toxicologically. Hence, the aim of this article is to emphasize the need to objectively assess the pros and cons of oxygen/ozone as a medical gas mixture in the hope that ozone therapy will be accepted by orthodox medicine in the near future. PMID:22146387

2011-01-01

442

Breathing gas mixtures different from air: an adaptation for survival under the ice of a facultative air-breathing fish.  

PubMed

Gaseous respiration by central mudminnows (Umbra limi), particularly their use of bubbles composed of gas mixtures other than air, may have evolved as an adaptation to the oxygen-depleted, carbon dioxide-rich water of winterkill lakes. Under simulated winterkill conditions, mudminnows frequently engulfed gaseous bubbles. Use of bubbles was not related to varying methane or nitrogen content (0 to 80 percent) when all bubbles contained 20 percent oxygen. When the oxygen content of bubbles varied (0 to 20 percent), fish visited bubbles randomly but remained longer and took fewer "breaths" at bubbles with high oxygen content. High temperature (16 degrees to 34 degrees C) and low pH (6.8 to 4.5) did not stimulate increased air-breathing when dissolved oxygen was sufficient. PMID:17732920

Magnuson, J J; Keller, J W; Beckel, A L; Gallepp, G W

1983-04-15

443

Observations of columnal recombination in the ionization tracks of energetic heavy nuclei in an argon-methane gas mixture  

NASA Technical Reports Server (NTRS)

Measurements of ionization signals resulting from the passage of energetic heavy nuclei through a gas mixture consisting of 95 mol percent Ar plus 5 mol percent CH4, at an absolute pressure of 3 atm are presented. The measurements take place under a uniform electric field perpendicular to the ionization track. The signals were compared to the calculated energy losses, with an assumption of proportionality between energy loss rate and ionization rate. Significant deviations from proportionality are found for energy loss rate grater than about 3000 MeV sq cm/g, while fractional deviations are found to be proportional to the energy loss rate (dE/dx) exp m, where m is equal to about two. These results are attributed to the columnal recombination.

Wiedenbeck, Mark E.

1990-01-01

444

Optical characteristics and parameters of gas-discharge plasma in a mixture of mercury dibromide vapor with argon  

NASA Astrophysics Data System (ADS)

Results are presented from studies of the optical characteristics and parameters of the plasma of a dielectric barrier discharge in a mixture of mercury dibromide vapor with argon—the working medium of an exciplex gas-discharge emitter. It is established that the partial pressures of mercury dibromide vapor and argon at which the average and pulsed emission intensities in the blue—green spectral region (?max = 502 nm) reach their maximum values are 0.6 and 114.4 kPa, respectively. The electron energy distribution function, the transport characteristics, the specific power spent on the processes involving electrons, the electron density and temperature, and the rate constants for the processes of elastic and inelastic electron scattering from the molecules and atoms of the working mixture are determined by numerical simulation, and their dependences on the reduced electric field strength are analyzed. The rate constant of the process leading to the formation of exciplex mercury monobromide molecules for a reduced electric field of E/ N = 20 Td, at which the maximum emission intensity in the blue—green spectral region was observed in this experiment, is found to be 8.1 × 10-15 m3/s.

Malinina, A. A.; Malinin, A. N.

2015-03-01

445

Collision-induced hyper-Rayleigh spectrum of H2-Ar gas mixture  

NASA Astrophysics Data System (ADS)

The collision-induced hyper-Rayleigh (CIHR) spectra of the gaseous H2-Ar mixture are discussed in the binary regime on the basis of our ab initio computed H2-Ar collision-induced (CI) first dipole hyperpolarizability tensor ??(R ). A method for the computation of the spherical, rotationally adapted components ???L(s,K)(R) of ??(R ) needed for spectroscopic line shape analysis is proposed. Both the vector and the septor parts of the H2-Ar CIHR spectrum are evaluated at room (T =295 K) temperature. The spectra are calculated assuming the full quantum computations based on the Schrödinger equation of the relative translational motion of H2-Ar as well as semiclassical methods (classical trajectory approach and Birnbaum-Cohen model translational profiles). The H2-Ar pair CIHR septor spectrum has been found stronger than the vector one.

Bancewicz, Tadeusz; G?az, Waldemar; Godet, Jean-Luc; Maroulis, George

2008-09-01

446

Discharge stabilization studies of CO laser gas mixtures in quasi-steady supersonic flow  

NASA Technical Reports Server (NTRS)

Experiments were conducted to study the applicability of a double discharge stabilization scheme in conditions appropriate for high energy CO lasers in supersonic flows. A Ludwieg tube impulse flow facility and a ballasted capacitor bank provided essentially steady flow and discharge conditions (d.c.) for times longer than ten electrode length-flow transit times. Steady, arc-free, volume discharges were produced in a Mach 3 test cavity using an auxiliary discharge to stabilize the main discharge in N2 and He/CO mixture. A signigicant result is the lack of observed plasma E/N changes in response to auxiliary discharge current changes. Also, where glow discharges were obtained, the energy loading achieved was very much less than the threshold level required for laser operation.

Srinivasan, G.; Smith, J. A.

1976-01-01

447

Comprehensive two-dimensional gas chromatography to characterize hydrocarbon mixtures in lithic materials.  

PubMed

The analysis of organic biomarkers in chert samples offers key information about the environmental conditions in which these samples were formed, and this information can be used to track the lithic materials of many archaeological artifacts. Since the content of the organic fraction is very low and the complexity of the organic extracts is quite high, we have optimized the GC×GC separation of these mixtures. Making use of mixture of C(16)H(34)-C(44)H(90)n-alkane standards, a central composite design was carried out taking into account the carrier flow in the first and second columns, the modulation period and the discharge time. Regarding the measured responses, though the initially considered one was the peak volume, we have also evaluated the effects on the number of modulated peaks per analyte, the symmetry of the modulated peaks and the number of detected compounds. The final optimum conditions were defined as follows: a hydrogen flow of 1.2 mL/min in the first column and 18 mL/min in the second one, a modulation period of 1.4 s and a discharge time of 0.1 s and under these conditions all the response variables showed optimum values. Based on this optimized method several chert samples obtained from different stratigraphic levels in an ancient quarry were studied and we were able to distinguish them on the basis of the different constituents of organic biomarkers, such as mono-methylated alkanes, cyclic n-alkanes, branched alkanes, steranes and hopanes. PMID:21333294

Olivares, M; Irazola, M; Vallejo, A; Murelaga, X; Zuloaga, O; Etxebarria, N

2011-03-25

448

High pressure laser plasma studies. [energy pathways in He-Ar gas mixtures at low pressure  

NASA Technical Reports Server (NTRS)

The operation of a nuclear pumped laser, operating at a wavelength of 1.79 micron m on the 3d(1/2-4p(3/2) transition in argon with helium-3 as the majority gas is discussed. The energy pathways in He-Ar gas were investigated by observing the effects of varying partial pressures on the emissions of levels lying above the 4p level in argon during a pulsed afterglow. An attempt is made to determine the population mechanisms of the 3d level in pure argon by observing emission from the same transition in a high pressure plasma excited by a high energy electron beam. Both collisional radiative and dissociative recombination are discussed.

Wells, W. E.

1980-01-01

449

Isobutanol-methanol mixtures from synthesis gas. Quarterly technical progress report, 1 October--31 December 1994  

SciTech Connect

Objective was to design a catalyst for synthesizing 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 designing catalyst for selective conversion of synthesis gas to isoalcohols. Activities during this period are reported; equipment reported include controlled pH precipitation unit, catalytic microreactor, and temperature programmed surface reaction/infrared unit.

Iglesia, E.

1994-12-31

450

An atom trap trace analysis (ATTA) system for measuring ultra-low contamination by krypton in xenon dark matter detectors  

NASA Astrophysics Data System (ADS)

The XENON dark matter experiment aims to detect hypothetical weakly interacting massive particles (WIMPs) scattering off nuclei within its liquid xenon (LXe) target. The trace 85Kr in the xenon target undergoes beta-decay with a 687 keV end point and 10.8 year halflife, which contributes background events and limits the sensitivity of the experiment. In order to achieve the desired sensitivity, the contamination by krypton is reduced to the part per trillion (ppt) level by cryogenic distillation. The conventional methods are not well suited for measuring the krypton contamination at such a low level. In this work, we have developed an atom trap trace analysis (ATTA) device to detect the ultra-low krypton concentration in the xenon target. This project was proposed to the National Science Foundation (NSF) as a Major Research Instrumentation (MRI) development [Aprile and Zelevinsky, 2009] and is funded by NSF and Columbia University. The ATTA method, originally developed at Argonne National Laboratory, uses standard laser cooling and trapping techniques, and counts single trapped atoms. Since the isotopic abundance of 85Kr in nature is 1.5 x 10-11, the 85Kr/Xe level is expected to be ˜10-23, which is beyond the capability of our method. Thus we detect the most abundant (57%) isotope 84Kr, and infer the 85Kr contamination from their known abundances. To avoid contamination by krypton, the setup is tested and optimized with 40 Ar which has a similar cooling wavelength to 84Kr. Two main challenges in this experiment are to obtain a trapping efficiency high enough to detect krypton impurities at the ppt level, and to achieve the resolution to discriminate single atoms. The device is specially designed and adjusted to meet these challenges. After achieving these criteria with argon gas, we precisely characterize the efficiency of the system using Kr-Xe mixtures with known ratios, and find that ˜90 minutes are required to trap one 84Kr atom at the 1-ppt Kr/Xe contamination. This thesis describes the design, construction, and experimental results of the ATTA project at Columbia University.

Yoon, Tae Hyun

451

Kinetics of chlorination of zirconia in mixture with petroleum coke by chlorine gas  

NASA Astrophysics Data System (ADS)

Studies on the kinetics of carbothermic chlorination of zirconium dioxide in gaseous chlorine were carried out with petroleum coke fines in powder form. The amounts of ZrO2 chlorinated were found to be directly proportional to the time of chlorination in the temperature range studied (973 to 1273 K). The activation energy values for chlorination of ZrO2, in mixture with petroleum coke, was found to be 18.3 kJ/mole. The influence of particle size of petroleum coke on the chlorination of ZrO2 (-38 + 25 µm) was studied, and it was found that the rate of chlorination increased up to the size range of -75 to +53 µm, and the size finer than this produced negligible increase. The amount of petroleum coke in the mixture above 17.41 pct in excess of the stoichiometry resulted in very little increase in the rate. The effect of the partial pressure of chlorine ( pCl2) on the rate of chlorination was found to obey the following relationship, derived from the Langmuir adsorption isotherm: v = {k \\cdot K \\cdot pCl_2 }/{l + K \\cdot pCl_2 } where v is the amount of ZrO2 (g/min) reacted, k is the rate constant, and K is the equilibrium constant for adsorption of two chlorine atoms (obtained from the dissociation of a molecule of Cl2 at the carbon surface) on the surface of ZrO2. By plotting 1/ v vs 1/ pCl2, a straight-line relationship with an intercept in x-axis is obtained, further supporting the preceding equation. The dissociation of the adsorbed complex, Cl … ZrO2 … Cl to ZrCl2 and O2 is suggested to be the rate-controlling step. Subsequently, the less stable ZrCl2 combines with Cl2 to form ZrCl4 and the oxygen combines with C to form CO and CO2.

Jena, P. K.; Brocchi, E. A.; Reis, M. L. Dos

1999-06-01

452

Torsional rheometer for granular materials slurries and gas-solid mixtures and related methods  

DOEpatents

A torsional rheometer apparatus for determining rheological properties of a specimen is provided. A stationary plate and a rotatable plate are in generally coaxial position and structured to receive a specimen therebetween. In one embodiment, at least one of the plates and preferably both have roughened specimen engaging surfaces to serve to reduce undesired slippage between the plate and the specimen. A motor is provided to rotate the rotatable plate and a transducer for monitoring forces applied to the stationary plate and generating output signals to a computer which determines the desired rheological properties are provided. In one embodiment, the roughened surfaces consist of projections extending toward the specimen. Where granular material is being evaluated, it is preferred that the roughness of the plate is generally equal to the average size of the granular material being processed. In another embodiment, an air-solid mixture is processed and the roughened portions are pore openings in the plates. Air flows through the region between the two pore containing plates to maintain the solid materials in suspension. In yet another embodiment, the base of the stationary plate is provided with a deformable capacitance sensor and associated electronic means.

Rajagopal, Chandrika (Allison Park, PA); Rajagopal, Kumbakonam R. (Allison Park, PA); Yalamanchili, Rattaya C. (Allison Park, PA)

1997-01-01

453

Torsional rheometer for granular materials slurries and gas-solid mixtures and related methods  

DOEpatents

A torsional rheometer apparatus for determining rheological properties of a specimen is provided. A stationary plate and a rotatable plate are in generally coaxial position and structured to receive a specimen there between. In one embodiment, at least one of the plates and preferably both have roughened specimen engaging surfaces to serve to reduce undesired slippage between the plate and the specimen. A motor is provided to rotate the rotatable plate and a transducer for monitoring forces applied to the stationary plate and generating output signals to a computer which determines the desired rheological properties are provided. In one embodiment, the roughened surfaces consist of projections extending toward the specimen. Where granular material is being evaluated, it is preferred that the roughness of the plate is generally equal to the average size of the granular material being processed. In another embodiment, an air-solid mixture is processed and the roughened portions are pore openings in the plates. Air flows through the region between the two pore containing plates to maintain the solid materials in suspension. In yet another embodiment, the base of the stationary plate is provided with a deformable capacitance sensor and associated electronic means. 17 figs.

Rajagopal, C.; Rajagopal, K.R.; Yalamanchili, R.C.

1997-03-11

454

Gas phase ion/molecule reactions in phosphine/germane mixtures studied by ion trapping  

NASA Astrophysics Data System (ADS)

Gaseous mixtures of phosphine and germane have been investigated by ion trap mass spectrometry. Reaction pathways together with rate constants of the main reactions are reported. The mechanisms of ion/molecule reactions have been elucidated by single and multiple isolation steps. The GeHn+ (n = 1-3) ions react with phosphine to give GePHn+ (n = 2-4) ions. The GePH4+ ion further reacts with GeH4 to yield Ge2PH6+. The GePHn+ (n = 2-4) mixed ionic family also originates from the P+ phosphine primary ion, as well as from the P2Hn+ (n = 0-3) secondary ions of phosphine reacting with neutral germane and from Ge2H2+ reacting with phosphine. The main reaction pathways of the PHn+ (n = 0-2) ions with GeH4 lead to the formation of the GeH2+ and GeH3+ ionic species. Protonation of phosphine from different ionic precursors is a very common process and yields the stable phosphonium ion, PH4+. Trends in total abundances of secondary GePHn+ (n = 2-4) ions as function of reaction time for different PH3/GeH4 pressure ratios show that excess of germane slightly affects the nucleation of mixed Ge-P ions.

Benzi, P.; Operti, L.; Rabezzana, R.; Splendore, M.; Volpe, P.

1996-01-01

455

Ultrapyrolytic upgrading of plastic wastes and plastics/heavy oil mixtures to valuable light gas products  

SciTech Connect

Viable operating conditions were identified experimentally for maximizing the production of high-value products such as ethylene, propylene, styrene, and benzene, from the ultrapyrolysis of waste plastics. Using both a batch microreactor and a pilot-plant-sized reactor, the key operating variables considered were pyrolysis temperature, product reaction time, and quench time. In the microreactor experiments, polystyrene (PS), a significant component of waste plastics, was pyrolyzed at temperatures ranging from 800 to 965 C, with total reaction times ranging from 500 to 1,000 ms. At a temperature of 965 C and 500 ms, the yields of styrene plus benzene were greater than 95 wt %. In the pilot-plant experiments, the recently patented internally circulating fluidized bed (ICFB) reactor (Milne et al., US Patent Number 5,370,789, 1994b) was used to ultrapyrolyze low-density polyethylene (LDPE) in addition to LDPE (5% by weight)/heavy oil mixtures at a residence time of 600 ms. Both experiments produced light olefin yields greater than 55 wt % at temperatures above 830 C.

Lovett, S.; Berruti, F.; Behie, L.A. [Univ. of Calgary, Alberta (Canada). Dept. of Chemical and Petroleum Engineering] [Univ. of Calgary, Alberta (Canada). Dept. of Chemical and Petroleum Engineering

1997-11-01

456

Inert Gas Dilution Effect on the Flammability Limits of Hydrocarbon Mixtures  

E-print Network

, in which the inert gas agents, mostly including nitrogen, carbon dioxide, and argon, are of interest, because they are not only non-ozone-depleting but also non-toxic and non-pyrolytic gases. 1.2 Objectives In this research, nitrogen dilution effect... with additional nitrogen using CAFT modeling?????...125 6.7 Methane LFL with additional carbon dioxide using CAFT modeling???...127 6.8 Propylene LFL with additional carbon dioxide using CAFT modeling???.128 6.9 Methane and propane LFL with additional nitrogen...

Zhao, Fuman

2012-02-14

457

Xenon fluoride solutions effective as fluorinating agents  

NASA Technical Reports Server (NTRS)

Solutions of xenon fluorides in anhydrous hydrogen fluoride have few disruptive effects and leave a residue consisting of gaseous xenon, which can be recovered and refluorinated. This mild agent can be used with materials which normally must be fluorinated with fluorine alone at high temperatures.

Hyman, H. H.; Quarterman, L. A.; Sheft, I.

1967-01-01

458

Xenon and Krypton in the Bruderheim Meteorite  

Microsoft Academic Search

In a series of heating experiments, xenon, radiogenic XeR, and krypton con- tents, and the xenon and krypton isotopic composition of the Bruderheim meteorite were studied for the separated minerals feldspar, pyroxene, olivine, and trollire and for numerous chondrule fractions. Important differences among the individual minerals and between min- erals and chondrules were observed, and the following conclusions were reached:

Craig Merrihue

1966-01-01

459

Reactions of xenon with iridium- and Osmiumhexafluoride.  

PubMed

Xenon and Iridiumhexafluoride react at temperatures above room temperature forming XeF+IrF6-. In presence of SbF5 FXe+IrSbF11- is formed. Xenon and Osmiumhexafluoride form in solution a blue charge transfer complex that cannot be isolated as a solid. PMID:24169702

Tamadon, Farhad; Seidel, Stefan; Seppelt, Konrad

2013-01-01

460

Results from the XENON1T Demonstrator  

NASA Astrophysics Data System (ADS)

The current stage of the XENON Dark Matter Search project, XENON100, constitutes one of the best performing dark matter experiments in the world, setting the best upper limit on the cross section for spin independent WIMP-nucleus scattering. The next generation detector within the program, XENON1T, is at the end of its design phase and construction will start in the present year. XENON1T is a liquid xenon dual-phase time projection chamber with a 1 Ton fiducial mass, and it will improve the present XENON100 limit by 2 orders of magnitude. However, the increase in mass in the new detector presents several technological challenges. In order to address the required improvements, a fully operational prototype of the detector, the XENON1T Demonstrator, has been built at Columbia University. In this talk we will present the main results of the XENON1T Demonstrator R&D program, comprising high-speed recirculation on a full-scale cryogenic system, the observation of electron drift over 30 cm, and the operation of the detector with a cathode high voltage exceeding 30kV and preliminary results of the new 60 and 100 cm setups.

Contreras, Hugo; Aprile, Elena; Budnik, Ranny; Goetzke, Luke; Plante, Guillaume; Messina, Marcello; Rizzo, Alfio; Melgarejo, Antonio; Naganoma, Junji; Chaguine, Petr

2013-04-01

461

Plasma diagnostics of r.f. PACVD of boron nitride using a BCl 3?N 2?H 2?Ar gas mixture  

Microsoft Academic Search

Boron nitride coatings have been synthesised by plasma-assisted chemical vapour deposition (PACVD) from a BCl3\\/N2\\/H2\\/Ar gas mixture in a hot wall capacitively coupled r.f. (13.56 MHz) system. The influence of the gas composition has been investigated in terms of the nature of active species in the plasma phase using optical emission spectroscopy and mass spectrometry. These characterisations have been correlated

C. Schaffnit; L. Thomas; F. Rossi; R. Hugon; Y. Pauleau

1998-01-01

462

Effect of operating variables on the gas holdup in a large-scale slurry bubble column reactor operating with an organic liquid mixture  

Microsoft Academic Search

The effects of gas velocity, system pressure, and catalyst loading on gas holdup of Hâ, Nâ, CO, and CHâ in an organic mixture of hexanes were investigated in a 0.316 m diameter, 2.8 m height slurry bubble column reactor operating with a commercial Fischer-Tropsch iron-based catalyst. The data were obtained in the churn-turbulent flow regime with catalyst loading up to

Juan R. Inga; Badie I. Morsi

1999-01-01

463

Nature of unresolved complex mixture in size-distributed emissions from residential wood combustion as measured by thermal desorption-gas chromatography-mass spectrometry  

Microsoft Academic Search

Unresolved complex mixture (UCM) is an analytical artifact of gas chromatographs of combustion source-related fine aerosol extracts. In this study the UCM is examined in size-resolved fine aerosol emissions from residential wood combustion. The aerosols are sorted by size in an electrical low-pressure impactor (ELPI) and subsequently analyzed by thermal desorption\\/gas chromatography\\/mass spectrometry (TD\\/GC\\/MS). A semiquantitative system for predicting the

Michael D. Hays; N. Dean Smith; Yuanji Dong

2004-01-01

464

Kinetics and mechanism of the desulfurization of liquid blast furnace slags by Ar-H2O gas mixtures  

NASA Astrophysics Data System (ADS)

The rate of evolution of sulfur-bearing gases from liquid silicate slags at 1400 ‡C when exposed to Ar-H2O gas mixtures has been studied. The rate was first order with respect both to the concentration of sulfur ions adsorbed on the surface of the slag and to the partial pressure of water vapor when PH 2O was greater than 0.15 atm. When the partial pressure of water vapor was less than 0.15 atm, the rate was second order with respect to the concentration of sulfur ions adsorbed on the surface early in the reaction. At longer times in the latter case, the rate was independent of the partial pressure of water vapor, but first order with respect to the concentration of sulfur ions adsorbed on the surface. It was concluded, based on the kinetics of desulfurization, that the sulfur-bearing species evolved from the surface of the slag was S2 when the rate was second order with respect to the concentration of adsorbed sulfur ions, but SO2 was evolved when the rate was first order with respect to the concentration of adsorbed sulfur ions. Under the conditions employed in the experiments, H2S never evolved from the surface of the slag, although it did form, in some instances, in the gas phase.

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

1983-06-01

465

Combustion of ultrafine coal/water mixtures and their application in gas turbines: Final report  

SciTech Connect

The feasibility of using coal-water fuels (CWF) in gas turbine combustors has been demonstrated in recent pilot plant experiments. The demands of burning coal-water fuels with high flame stability, complete combustion, low NO/sub x/ emission and a resulting fly ash particle size that will not erode turbine blades represent a significant challenge to combustion scientists and engineers. The satisfactory solution of these problems requires that the variation of the structure of CWF flames, i.e., the fields of flow, temperature and chemical species concentration in the flame, with operating conditions is known. Detailed in-flame measurements are difficult at elevated pressures and it has been proposed to carry out such experiments at atmospheric pressure and interpret the data by means of models for gas turbine combustor conditions. The research was carried out in five sequential tasks: cold flow studies; studies of conventional fine-grind CWF; combustion studies with ultrafine CWF fuel; reduction of NO/sub x/ emission by staged combustion; and data interpretation-ignition and radiation aspects. 37 refs., 61 figs., 9 tabs.

Toqan, M.A.; Srinivasachar, S.; Staudt, J.; Varela, F.; Beer, J.M.

1987-10-01

466

Xenon geochronology of Schwarzwald pitchblendes  

Microsoft Academic Search

The uranium- \\/fission-xenon systems in eleven samples selected from three occurrences in the Schwarz- wald were investigated\\u000a (Menzenschwand, Wittichen, M?llenbach). Relationships between mineralogical properties, Xe release profiles and Xe-Xe age\\u000a spectra provide criteria for sample suitability for U-Xe and Xe-Xe dating and interpretation of the Xe-Xe age spectra. U leaching\\u000a from pitchblendes was demonstrated for three of the Wittichen samples,

A. P. Meshik; H. J. Lippolt; Yu. M. Dymkov

2000-01-01

467

NATURE OF UNRESOLVED COMPLEX MIXTURE IN SIZE-DISTRIBUTED EMISSIONS FROM RESIDENTIAL WOOD COMBUSTION AS MEASURED BY THERMAL DESORPTION-GAS CHROMATOGRAPHY-MASS SPECTROMETRY  

EPA Science Inventory

In this study, the unresolved complex mixture (UCM) in size resolved fine aerosol emissions from residential wood combustion (RWC) is examined. The aerosols are sorted by size in an electrical low-pressure impactor (ELPI) and subsequently analyzed by thermal desorbtion/gas chroma...

468

Quantum cascade laser investigations of CH4 and C2H2 interconversion in hydrocarbon/H2 gas mixtures during microwave plasma  

E-print Network

3 Skobel'tsyn Institute of Nuclear Physics, Moscow State University, Leninskie Gory, Moscow 119991 periphery of the reactor. Nonetheless, the measurements prove to be of enormous value in testing, tensioning in hydrogen gas mixtures finds widespread use as a route to growing