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Sample records for ar gas filled

  1. Test beam studies of the TRD prototype filled with different gas mixtures based on Xe, Kr, and Ar

    NASA Astrophysics Data System (ADS)

    Celebi, E.; Brooks, T.; Joos, M.; Rembser, C.; Gurbuz, S.; Cetin, S. A.; Konovalov, S. P.; Tikhomirov, V. O.; Zhukov, K.; Fillipov, K. A.; Romaniouk, A.; Smirnov, S. Yu; Teterin, P. E.; Vorobev, K. A.; Boldyrev, A. S.; Maevsky, A.; Derendarz, D.

    2017-01-01

    Towards the end of LHC Run1, gas leaks were observed in some parts of the Transition Radiation Tracker (TRT) of ATLAS. Due to these leaks, primary Xenon based gas mixture was replaced with Argon based mixture in various parts. Test-beam studies with a dedicated Transition Radiation Detector (TRD) prototype were carried out in 2015 in order to understand transition radiation performance with mixtures based on Argon and Krypton. We present and discuss the results of these test-beam studies with different active gas compositions.

  2. Gas filled panel insulation

    DOEpatents

    Griffith, B.T.; Arasteh, D.K.; Selkowitz, S.E.

    1993-12-14

    A structural or flexible highly insulative panel which may be translucent, is formed from multi-layer polymeric material in the form of an envelope surrounding a baffle. The baffle is designed so as to minimize heat transfer across the panel, by using material which forms substantially closed spaces to suppress convection of the low conductivity gas fill. At least a portion of the baffle carries a low emissivity surface for suppression of infrared radiation. 18 figures.

  3. Gas filled panel insulation

    DOEpatents

    Griffith, Brent T.; Arasteh, Dariush K.; Selkowitz, Stephen E.

    1993-01-01

    A structural or flexible highly insulative panel which may be translucent, is formed from multi-layer polymeric material in the form of an envelope surrounding a baffle. The baffle is designed so as to minimize heat transfer across the panel, by using material which forms substantially closed spaces to suppress convection of the low conductivity gas fill. At least a portion of the baffle carries a low emissivity surface for suppression of infrared radiation.

  4. Gas-Filled Capillary Model

    NASA Astrophysics Data System (ADS)

    Steinhauer, L. C.; Kimura, W. D.

    2006-11-01

    We have developed a 1-D, quasi-steady-state numerical model for a gas-filled capillary discharge that is designed to aid in selecting the optimum capillary radius in order to guide a laser beam with the required intensity through the capillary. The model also includes the option for an external solenoid B-field around the capillary, which increases the depth of the parabolic density channel in the capillary, thereby allowing for propagation of smaller laser beam waists. The model has been used to select the parameters for gas-filled capillaries to be utilized during the Staged Electron Laser Acceleration — Laser Wakefield (STELLA-LW) experiment.

  5. Improved gas mixtures for gas-filled particle detectors

    DOEpatents

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

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

  6. Gas mixtures for gas-filled particle detectors

    DOEpatents

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

    1980-01-01

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

  7. Gap Fill Materials Using Cyclodextrin Derivatives in ArF Lithography

    NASA Astrophysics Data System (ADS)

    Takei, Satoshi; Shinjo, Tetsuya; Sakaida, Yasushi; Hashimoto, Keisuke

    2007-11-01

    High planarizing gap fill materials based on β-cyclodextrin in ArF photoresist under-layer materials have been developed for fast etching in CF4 gas. Gap fill materials used in the via-first dual damascene process need to have high etch rates to prevent crowning or fencing on top of the trench after etching and a small thickness bias between the dense and blanket areas to minimize issues observed during trench lithography by narrowing the process latitude. Cyclodextrin is a circular oligomer with a nanoscale porous structure that has a high number of oxygen atoms, as calculated using the Ohnishi parameter, providing high etch rates. Additionally, since gap fill materials using cyclodextrin derivatives have low viscosities and molecular weights, they are expected to exhibit excellent flow properties and minimal thermal shrinkage during baking. In this paper, we describe the composition and basic film properties of gap fill materials; planarization in the via-first dual damascene process and etch rates in CF4 gas compared with dextrin with α-glycoside bonds in polysaccharide, poly(2-hydroxypropyl methacrylate) and poly(4-hydroxystyrene). The β-cyclodextrin used in this study was obtained by esterifying the hydroxyl groups of dextrin resulting in improved wettability on via substrates and solubility in photoresist solvents such as propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and ethyl lactate. Gap fill materials using cyclodextrin derivatives showed good planarization and via filling performance without observing voids in via holes. In addition to superior via filling performance, the etch rate of gap fill materials using β-cyclodextrin derivatives was 2.8-2.9 times higher than that of an ArF photoresist, evaluated under CF4 gas conditions by reactive ion etching. These results were attributed to the combination of both nanoscale porous structures and a high density of oxygen atoms in our gap fill materials using cyclodextrin

  8. Alpha gas state in 36Ar

    NASA Astrophysics Data System (ADS)

    Akimune, Hidetoshi; Gibelin, Julien; Harakeh, Muhsin; Itoh, Masatoshi; Kawabata, Takahiro; Tamii, Atsushi; Fujiwara, Mamoru; Miki, Kenjiro; Iwamoto, Chiro; Otsu, Hideaki; Oha, Shinsuke; Tanihata, Isao; Muramoto, Tomoyuki; Kadono, Chika; Kalantar, Nasser; Ando, Shun; Leblond, Sylvian; Ayyad, Yassid; Furuno, Tatsuya; Tsynyra, Miho; Baba, Tasuo; Adachi, Satoshi; Freer, Martin

    2014-09-01

    The α cluster structures in light nuclei with N = Z are expected to appear abov the threshold energy of breakup into α particles. After the proposal of an α cluster wave function with α particle condensate type, such condensate states are both theoretically and experimentally discussed extensively. Theoretically, the existence of dilute α cluster state in nuclei with mass region of A > 16, experimentally, is not confirmed for N- α cluster states in nuclei heavier than A = 16. Recently, we measured α inelastic scattering of 36Ar followed by α decay in an inverse kinematics setup. A 50 MeV/u 36Ar beam from RCNP ring cyclotron was used to bombard a 4He gas target. α particles were detected in the magnetic spectrometer LAS which was set at 0 degrees. The α cluster structures in light nuclei with N = Z are expected to appear abov the threshold energy of breakup into α particles. After the proposal of an α cluster wave function with α particle condensate type, such condensate states are both theoretically and experimentally discussed extensively. Theoretically, the existence of dilute α cluster state in nuclei with mass region of A > 16, experimentally, is not confirmed for N- α cluster states in nuclei heavier than A = 16. Recently, we measured α inelastic scattering of 36Ar followed by α decay in an inverse kinematics setup. A 50 MeV/u 36Ar beam from RCNP ring cyclotron was used to bombard a 4He gas target. α particles were detected in the magnetic spectrometer LAS which was set at 0 degrees. Taro Hirao Grant-in-Aid for Scientific Research.

  9. Essential Characteristics of Plasma Antennas Filled with He-Ar Penning Gases

    NASA Astrophysics Data System (ADS)

    Sun, Naifeng; Li, Wenzhong; Wang, Shiqing; Li, Jian; Ci, Jiaxiang

    2012-09-01

    Based on the essential theory of Penning gases, the discharge characteristics of He-Ar Penning gases in insulating tubes were analyzed qualitatively. The relation between the effective length of an antenna column filled with He-Ar Penning gases and the applied radio frequency (RF) power was investigated both theoretically and experimentally. The distribution of the plasma density along the antenna column in different conditions was studied. The receiving characteristics of local frequency modulated (FM) electromagnetic waves by the plasma antenna filled with He-Ar Penning gases were compared with those by an aluminum antenna with the same dimensions. Results show that it is feasible to take plasma antennas filled with He-Ar Penning gases as receiving antennas.

  10. Improved gas mixtures for gas-filled radiation detectors

    DOEpatents

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

    1980-03-28

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

  11. Gas mixtures for gas-filled radiation detectors

    DOEpatents

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

    1982-01-05

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

  12. Handbook for Gas Filled RF Cavity Aficionados'

    SciTech Connect

    Tollestrup, A.V.; Chung, Moses; Yonehara, Katsuya; /Fermilab

    2009-05-01

    The use of hydrogen gas filled RF cavities in muon cooling channels has been proposed by Rolland Johnson. Impressive results have been obtained toward attaining high voltage gradients and rapid training in preliminary tests done at the FNAL MTA facility. However, so far it has not been possible to test them under conditions where they were subject to the transversal of a high intensity particle beam. This note is an attempt to bring together a description of some of the pertinent physical processes that take place in the dilute plasma that is generated in the hydrogen gas by the beam. Two effects dominate. The first is that the free electrons generated can load down the cavity and transfer its energy to heating the gas. The second is a question of what happens to the plasma in the longer term. There is an enormous literature on the subject of the subject of dilute hydrogen plasmas and we can tap into this information in order to understand and predict the behavior of the cavity.

  13. The Performance of Gas Filled Multilayer Insulation

    NASA Astrophysics Data System (ADS)

    Mills, G. L.; Zeller, C. M.

    2008-03-01

    The NASA Exploration Program is currently planning to use liquid oxygen, methane and hydrogen for propulsion in future spacecraft for the human exploration of the Moon and Mars. This will require the efficient long term, on-orbit storage of these cryogens. Multilayer insulation (MLI) will be critical to achieving the required thermal performance since it has much lower heat transfer than any other insulation when used in a vacuum. However, the size and mass constraints of these propulsion systems will not allow a structural shell to be used to provide vacuum for the MLI during ground hold and launch. One approach is to purge the MLI during ground hold with an inert gas which is then vented during launch ascent and on-orbit. In this paper, we report on experimental tests and modeling that we have done on MLI used to insulate a cryogenic tank. These include measurements of the heat transfer of gas filled insulation, evacuated insulation and during the transition in between.

  14. Improved Gas Filling and Sealing of an HC-PCF

    NASA Technical Reports Server (NTRS)

    Poberezhskiy, Ilya; Meras, Patrick; Chang, Daniel; Spiers, Gary

    2008-01-01

    An improved packaging approach has been devised for filling a hollow-core photonic-crystal fiber (HC-PCF) with a gas, sealing the HC-PCF to retain the gas, and providing for optical connections and, optionally, a plumbing fitting for changing or augmenting the gas filling. Gas-filled HC-PCFs can be many meters long and have been found to be attractive as relatively compact, lightweight, rugged alternatives to conventional gas-filled glass cells for use as molecular-resonance frequency references for stabilization of lasers in some optical-metrology, lidar, optical-communication, and other advanced applications. Prior approaches to gas filling and sealing of HC-PCFs have involved, variously, omission of any attempt to connectorize the PCF, connectorization inside a vacuum chamber (an awkward and expensive process), or temporary exposure of one end of an HC-PCF to the atmosphere, potentially resulting in contamination of the gas filling. Prior approaches have also involved, variously, fusion splicing of HC-PCFs with other optical fibers or other termination techniques that give rise to Fresnel reflections of about 4 percent, which results in output intensity noise.

  15. Gas-filled hohlraum study on Shenguang-III prototype

    NASA Astrophysics Data System (ADS)

    Yang, Dong; Li, Sanwei; Li, Zhichao; Yi, Rongqing; Guo, Liang; Jiang, Xiaohua; Liu, Shenye; Yang, Jiamin; Jiang, Shaoen; Ding, Yongkun; Hao, Liang; Zhang, Huasen; Zhao, Yiqing; Zou, Shiyang; Huo, Wenyi; Li, Xin

    2015-11-01

    Experimental studies on gas-filled hohlraum were performed extensively in recent years on Shenguang-III prototype laser facility. These experiments employed Au hohlraums within C5H12 gas fill heated by smoothing beams. In the first round of experiments, although the low-Z gas fill impeded the blow-off plasma ablated from hohlraum wall, the x-ray flux from the LEH decreased dramatically compared with the vacuum hohlraum. Further analysis of several ways of energy deposition including heating the gas-fill, extra scattered light and ablating the LEH membrane, revealed that too much laser energy were wasted in exploding the LEH membrane if we use a 1 ns square pulse. After we introduced a low power prepulse to intentionally exploding the membrane, the behavior of the x-ray flux from the gas-filled hohlraum is identical with the vacuum hohlraum. In subsequent studies, the motion of x-ray spot and corona plasma has also been studied using the gas-filled hohlraum. We obtained high quality data of the gas/wall interface and the boundary of the ablated wall near the LEH. The result agrees with that in simulation. However, there is a discrepancy between the experiment and the simulation in the spatial feature of the ablated wall near the LEH extracted from M-band x-ray image.

  16. Gas Filled Coaxial Accelerator with Compression Coil

    NASA Technical Reports Server (NTRS)

    Espy, Patrick N. (Inventor)

    1976-01-01

    A self-energized plasma compressor which compresses plasma discharged from a coaxial plasma generator. The device includes a helical shaped coil which is coaxially aligned with the center axis of the coaxial plasma generator. The plasma generator creates a current through the helical coil which, in turn, generates a time varying magnetic field that generates a force which acts radially upon the plasma. A seal is carried on the end of the coaxial plasma generator for containing gas therein. As the plasma is accelerated out the outer end of the generator, it forces the gas outwardly also compressing such. Beads are carried adjacent the small end of the helical shaped coil for being accelerated to hypervelocities by the plasma and gas. As a result of utilizing gas in the coaxial plasma generator, such minimizes ablation of the beads as well as accelerates such to higher velocities.

  17. Evolution of gas-filled nanocracks in crystalline solids.

    PubMed

    Hartmann, M; Trinkaus, H

    2002-02-04

    In this work, the evolution of gas-filled cracks under gas implantation and subsequent annealing is studied on the basis of an elastic continuum approach. The observed growth limitation of He-filled nanocracks in SiC is attributed to their stabilization by the formation of circular dislocation dipoles. The formation and Ostwald ripening of bubble-loop complexes at elevated temperatures is modeled in terms of gas atom exchange between such complexes coupled with local matrix atom exchange between bubbles and loops of the same complex. The scaling laws derived for the time dependence of bubble and loop sizes are found to be in good agreement with experimental data.

  18. Attempts to Produce D2-Gas-Filled Be Shells

    SciTech Connect

    Cook, B; McElfresh, M; Alford, C; Fought, E; Letts, S

    2005-01-14

    We have attempted to fabricate some 0.5 mm diameter D{sub 2}-gas-filled Be shells by coating gas-filled PVA-coated GDP mandrels with Cu-doped Be. We find that during the coating all (or most) of the gas leaks out. This is likely due to either small cracks or holes in the coating that are formed at the earliest points and are maintained during the thickness build-up of the coating, and/or to some level of intrinsic porosity in the coating. This memo documents our efforts.

  19. A Gas Proportional Scintillation Counter with krypton filling

    NASA Astrophysics Data System (ADS)

    Monteiro, C. M. B.; Mano, R. D. P.; Barata, E. C. G. M.; Fernandes, L. M. P.; Freitas, E. D. C.

    2016-12-01

    A Gas Proportional Scintillation Counter filled with pure krypton was studied. Energy resolution below 10% for 5.9-keV X-rays was obtained with this prototype. This value is much better than the energy resolution obtained with proportional counters or other MPGDs with krypton filling. The krypton electroluminescence scintillation and ionisation thresholds were found to be about 0.5 and 3.5 kV cm-1bar-1, respectively.

  20. Attosecond pulses generated by the lighthouse effect in Ar gas

    NASA Astrophysics Data System (ADS)

    Tosa, Valer; Lee, Ji Su; Kim, Hyung Taek; Nam, Chang Hee

    2015-05-01

    We numerically investigate harmonic generation in Ar gas under high ionization conditions and demonstrate that a lighthouse effect is present. We examine the structure of the driving field during propagation in temporal, spectral, and spatial domains, and conclude that the complete depletion of neutral Ar on axis gives rise to additional wavelets at off-axis regions. We show that these wavelets propagate with increasing divergence as the radial distances from the axis increase, generating the rotation of the wave front, thus fulfilling a necessary condition for the lighthouse effect. We obtain attosecond bursts of light emitted with different divergences in successive optical half-cycles so that in the far field these bursts arrive at different distances from the beam axis.

  1. Shockwave compression of Ar gas at several initial densities

    NASA Astrophysics Data System (ADS)

    Dattelbaum, Dana M.; Goodwin, Peter M.; Garcia, Daniel B.; Gustavsen, Richard L.; Lang, John M.; Aslam, Tariq D.; Sheffield, Stephen A.; Gibson, Lloyd L.; Morris, John S.

    2017-01-01

    Experimental data of the principal Hugoniot locus of variable density gas-phase noble and molecular gases are rare. The majority of shock Hugoniot data is either from shock tube experiments on low-pressure gases or from plate impact experiments on cryogenic, liquefied gases. In both cases, physics regarding shock compressibility, thresholds for the on-set of shock-driven ionization, and even dissociation chemistry are difficult to infer for gases at intermediate densities. We have developed an experimental target design for gas gun-driven plate impact experiments on noble gases at initial pressures between 200-1000 psi. Using optical velocimetry, we are able to directly determine both the shock and particle velocities of the gas on the principal Hugoniot locus, as well as clearly differentiate ionization thresholds. The target design also results in multiply shocking the gas in a quasi-isentropic fashion yielding off-Hugoniot compression data. We describe the results of a series of plate impact experiments on Ar with starting densities between 0.02-0.05 g/cm3 at room temperature. Furthermore, by coupling optical fibers to the targets, we have measured the time-resolved optical emission from the shocked gas using a spectrometer coupled to an optical streak camera to spectrally-resolve the emission, and with a 5-color optical pyrometer for temperature determination.

  2. Application of gas-filled detectors for well logging

    NASA Astrophysics Data System (ADS)

    Korkin, R.; Baru, S. E.; Porosev, V. V.; Savinov, G. A.

    2008-06-01

    The advantages of using gas-filled multiwire proportional chambers (MWPC) for well logging are discussed. In particular, applicability of the MWPC in casing quality control and cement bond logging is described. It is shown that spatial distribution measurement of scattered gamma rays can provide information about the material and presence of the defects. The results of computations performed with GEANT4 are in the reasonable agreement with the experimental data.

  3. Gas amplification factor in neon-nitrogen filled proportional counters

    NASA Astrophysics Data System (ADS)

    Othman, A.

    1988-07-01

    The gas amplification factor in a cylindrical proportional counter filled with NeN 2 Penning mixtures has been measured (over the range 1 < A < 6.4 × 10 3) to verify the validity of the gas gain formulae of Rose and Korff, Khristov, Williams and Sara, Diethorn and Zastawny. This factor has been found to obey Zastawny's formula over the range of variables studied. The formula of Diethorn can be fitted only for small nitrogen concentrations (below 5 × 10 -4). Constants appropriate to the Zastawny and Diethorn formulae have been determined over a wide range of N 2 concentrations from spectroscopically pure Ne up to 11.1% N 2.

  4. Thermal Performance Evaluation of Walls with Gas Filled Panel Insulation

    SciTech Connect

    Shrestha, Som S.; Desjarlais, Andre Omer; Atchley, Jerald Allen

    2014-11-01

    Gas filled insulation panels (GFP) are very light weight and compact (when uninflated) advanced insulation products. GFPs consist of multiple layers of thin, low emittance (low-e) metalized aluminum. When expanded, the internal, low-e aluminum layers form a honeycomb structure. These baffled polymer chambers are enveloped by a sealed barrier and filled with either air or a low-conductivity gas. The sealed exterior aluminum foil barrier films provide thermal resistance, flammability protection, and properties to contain air or a low conductivity inert gas. This product was initially developed with a grant from the U.S. Department of Energy. The unexpanded product is nearly flat for easy storage and transport. Therefore, transportation volume and weight of the GFP to fill unit volume of wall cavity is much smaller compared to that of other conventional insulation products. This feature makes this product appealing to use at Army Contingency Basing, when transportation cost is significant compared to the cost of materials. The objective of this study is to evaluate thermal performance of walls, similar to those used at typical Barracks Hut (B-Hut) hard shelters, when GFPs are used in the wall cavities. Oak Ridge National Laboratory (ORNL) tested performance of the wall in the rotatable guarded hotbox (RGHB) according to the ASTM C 1363 standard test method.

  5. Systems and methods for regulating pressure of a filled-in gas

    DOEpatents

    Stautner, Ernst Wolfgang; Michael, Joseph Darryl

    2016-05-03

    A system for regulating a pressure of a filled-in gas is presented. The system includes a reservoir that stores a reservoir gas adsorbed in a sorbent material at a storage temperature, a gas-filled tube containing the filled-in gas, a controller configured to determine a pressure change required in the filled-in gas based upon signals representative of a pressure of the filled-in gas inside the gas-filled tube and a required pressure threshold, determine an updated temperature of the sorbent material based upon the pressure change required in the filled-in gas, and regulate the pressure of the filled-in gas by controlling the reservoir to change the storage temperature of the sorbent material to reach the updated temperature of the sorbent material.

  6. Testing of a prototype of calibration facility for noble gas monitoring using 41Ar.

    PubMed

    Saibathulham, Holnisar; Wurdiyanto, Gatot; Marsum, Pujadi

    2012-09-01

    A prototype of a calibration facility for noble gas monitoring using (41)Ar in the PTKMR-BATAN has been tested. The facility was designed in such a way that the standard source of gas can be reused. The radioactive (41)Ar source was obtained by thermal neutron reaction of (40)Ar(n, γ)(41)Ar using a thermal neutron flux of 4.8×10(13) neutrons per cm(2) per second in two minutes on the multipurpose G.A. Siwabessy Reactor (Batan, Serpong, Indonesia). Gamma spectrometry was used to measure the radioactivity and purity of (41)Ar. The spectrum of the (41)Ar observed yields an energy of 1294 keV because of the highest intensity (99.2%). The activity of (41)Ar was 2821 kBq and 4% of the expanded uncertainty. The time required for (41)Ar to reach homogeneity was 7 min, and the effectiveness of resuse was 53%.

  7. New Pliocene-Pleistocene 40Ar/ 39Ar ages fill in temporal gaps in the Nicaraguan volcanic record

    NASA Astrophysics Data System (ADS)

    Saginor, Ian; Gazel, Esteban; Carr, Michael J.; Swisher, Carl C., III; Turrin, Brent

    2011-04-01

    The volcanic record of western Nicaragua documents a significant lull in volcanic activity that has persisted from the late Miocene (~ 7 Ma) to the formation of the modern volcanic front around 350 ka. This study fills this gap for the first time with samples collected in Northwest Nicaragua between Cosigüina and San Cristóbal volcanoes and with samples collected from the Nicaraguan Depression. We found two previously unknown volcanic units ranging from 3.6 to 1.3 Ma and the improved volcanic record allows us to reconstruct the geochemical evolution of the Nicaraguan arc. U/Th values increased by nearly threefold since the Miocene following the "carbonate crash" at 10 Ma, when dominantly carbonate sediment deposition shifted toward hemipelagic sediment deposition. This transition was thought to be abrupt, however our new data show that it took place gradually over the last 7 Ma. Northwest Nicaragua is a particularly interesting case study because it contains Middle Miocene volcanism on either side of the Nicaraguan Depression, the Coyol Formation (25-7 Ma) to the East and the Tamarindo Formation (14.7-11.7 Ma) to the West. The presence of Mid Miocene volcanism on either side of the Nicaraguan Depression has led to the hypothesis that the two coeval units, currently separated by ~ 100 km, were once connected and have since been separated by extension. Here, we present data suggesting that the Tamarindo and Coyol are geochemically distinct and therefore cannot be considered part of the same unit.

  8. The Thermo Scientific HELIX-SFT noble gas mass spectrometer: (preliminary) performance for 40Ar/39Ar geochronology

    NASA Astrophysics Data System (ADS)

    Barfod, D. N.; Mark, D. F.; Morgan, L. E.; Tomkinson, T.; Stuart, F.; Imlach, J.; Hamilton, D.

    2011-12-01

    The Thermo Scientific HELIX-platform Split Flight Tube (HELIX-SFT) noble gas mass spectrometer is specifically designed for simultaneous collection of helium isotopes. The high mass spur houses a switchable 1011 - 1012 Ω resistor Faraday cup and the low mass spur a digital pulse-counting secondary electron multiplier (SEM). We have acquired the HELIX-SFT with the specific intention to measure argon isotopes for 40Ar/39Ar geochronology. This contribution will discuss preliminary performance (resolution, reproducibility, precision etc.) with respect to measuring argon isotope ratios for 40Ar/39Ar dating of geological materials. We anticipate the greatest impact for 40Ar/39Ar dating will be increased accuracy and precision, especially as we approach the techniques younger limit. Working with Thermo Scientific we have subtly modified the source, alpha and collector slits of the HELIX-SFT mass spectrometer to improve its resolution for resolving isobaric interferences at masses 36 to 40. The enhanced performance will allow for accurate and precise measurement of argon isotopes. Preliminary investigations show that we can obtain a valley resolution of >700 and >1300 (compared to standard HELIX-SFT specifications of >400 and >700) for the high and low mass spurs, respectively. The improvement allows for full resolution of hydrocarbons (C3+) at masses 37 - 40 and almost full resolution at mass 36. The HELIX-SFT will collect data in dual collection mode with 40Ar+ ion beams measured using the switchable 1011 - 1012 Ω resistor Faraday cup and 39Ar through 36Ar measured using the SEM. The HELIX-SFT requires Faraday-SEM inter-calibration but negates the necessity to inter-calibrate multiple electron multipliers. We will further present preliminary data from the dating of mineral standards: Alder Creek sanidine, Fish Canyon sanidine and Mount Dromedary biotite (GA1550).

  9. Computing at the Dubna gas-filled recoil separator

    NASA Astrophysics Data System (ADS)

    Tsyganov, Yuri S.; Polyakov, Alexandr N.

    2006-03-01

    Simulation codes for the spectra of heavy implanted nuclei, applications for online data visualization and real time PC-based algorithms are considered. Special attention is paid to the application of real time techniques for radical suppression of background products in heavy-ion-induced nuclear reactions at the U-400 cyclotron of the Flerov Laboratory of Nuclear Reactions. The detection system of the Dubna gas-filled recoil separator (DGFRS) is also briefly described. Calculated heavy recoil spectra are compared with those measured in heavy-ion-induced nuclear reactions.

  10. The Yale Gas-Filled Split Pole Magnetic Separator

    NASA Astrophysics Data System (ADS)

    Cata-Danil, G.; Beausang, C. W.; Casten, R. F.; Chen, A.; Chubrich, N.; Cooper, J. R.; Krücken, R.; Liu, B.; Novak, J. R.; Visser, D.; Zamfir, N. V.

    1998-10-01

    Design and construction of a gas-filled recoil separator is underway at the Wright Nuclear Structure Laboratory at Yale University. By filling the magnetic field region of the existing Enge Split-Pole magnet with N2 or He2 gases in the 1 to 15 mbar pressure range a gradual focussing of discrete charge states has been measured. The incident ions were ^16O and ^35,37Cl with 49 MeV and 95 MeV energies, respectively. The process is understood as a result of coalescing of trajectories of different charge states around a trajectory defined by the mean charge state (q¯) of the ion in gas. Because q¯ depends on the atomic number Z and is roughly proportional with the ion velocity, the average magnetic rigidity (B¯ρ=Av/q¯) is almost independent of the velocity distribution of the incident ions. The ion trajectories will be therefore be mainly determined by the mass number A and the atomic number Z of the ion. Monte Carlo simulations with the code RAYTRACE closely reproduce the experimental behavior. We plan to use the Yale Mass Separator (YaMS) for nuclear structure studies in conjunction with high efficency gamma detectors (clover detectors) for enhancing weak reaction channels and fission background reduction. Work supported by the US-DOE under contract numbers DE-FG02-91ER-40609 and DE-FG02-88ER-40417.

  11. Transit time of electrons and gas gain effects in P-10 and Ar+CO2

    NASA Astrophysics Data System (ADS)

    Orchard, Gloria M.; Waker, Anthony J.

    2014-11-01

    An Electron Mobility Spectrometer (EMS) has been designed to measure the transit time and electron attachment effects in proportional counter fill gases. The aim of the EMS is to observe how electron parameters including the drift velocity, pulse formation time, multiplication gain and electron attachment depend on the gas composition and operating parameters of the EMS. The operating parameters of interest for the EMS include the applied high voltage and gas pressure. Current research interests include the measurement of the time between the generation of the electron-ion pairs and arrival of the electrons at the wire anode in P-10 and Ar+CO2 gases. Additionally, the study of the multiplication properties of the detector as a function of pulse formation time in the two gases and as a function of applied electric field will be presented. The overall objective of this work is to investigate if the gas-gain of a proportional counter can be optimized by minimizing electron attachment with oxygen to improve the measurement of tritium in air.

  12. Polystyrene Foam Products Equation of State as a Function of Porosity and Fill Gas

    NASA Astrophysics Data System (ADS)

    Mulford, R. N.; Swift, D. C.

    2009-12-01

    An accurate EOS for polystyrene foam is necessary for analysis of numerous experiments in shock compression, inertial confinement fusion, and astrophysics. Plastic to gas ratios vary between various samples of foam, according to the density and cell-size of the foam. A matrix of compositions has been investigated, allowing prediction of foam response as a function of the plastic-to-air ratio. The EOS code CHEETAH allows participation of the air in the decomposition reaction of the foam. Differences between air-filled, Ar-blown, and CO2-blown foams are investigated, to estimate the importance of allowing air to react with products of polystyrene decomposition. O2-blown foams are included in some comparisons, to amplify any consequences of reaction with oxygen in air. He-blown foams are included in some comparisons, to provide an extremum of density. Product pressures are slightly higher for oxygen-containing fill gases than for non-oxygen-containing fill gases. Examination of product species indicates that CO2 decomposes at high temperatures.

  13. Polystyrene foam products equation of state as a function of porosity and fill gas

    SciTech Connect

    Mulford, Roberta N; Swift, Damian C

    2009-01-01

    An accurate EOS for polystyrene foam is necessary for analysis of numerous experiments in shock compression, inertial confinement fusion, and astrophysics. Plastic to gas ratios vary between various samples of foam, according to the density and cell-size of the foam. A matrix of compositions has been investigated, allowing prediction of foam response as a function of the plastic-to-air ratio. The EOS code CHEETAH allows participation of the air in the decomposition reaction of the foam. Differences between air-filled, Ar-blown, and CO{sub 2}-blown foams are investigated, to estimate the importance of allowing air to react with products of polystyrene decomposition. O{sub 2}-blown foams are included in some comparisons, to amplify any consequences of reaction with oxygen in air. He-blown foams are included in some comparisons, to provide an extremum of density. Product pressures are slightly higher for oxygen-containing fill gases than for non-oxygen-containing fill gases. Examination of product species indicates that CO{sub 2} decomposes at high temperatures.

  14. A compact gas-filled avalanche counter for DANCE

    SciTech Connect

    Wu, C. Y.; Chyzh, A.; Kwan, E.; Henderson, R. A.; Gostic, J. M.; Carter, D.; Bredeweg, T. A.; Couture, A.; Jandel, M.; Ullmann, J. L.

    2012-08-04

    A compact gas-filled avalanche counter for the detection of fission fragments was developed for a highly segmented 4π γ-ray calorimeter, namely the Detector for Advanced Neutron Capture Experiments located at the Lujan Center of the Los Alamos Neutron Science Center. It has been used successfully for experiments with 235U, 238Pu,239Pu, and 241Pu isotopes to provide a unique signature to differentiate the fission from the competing neutron-capture reaction channel. We also used it to study the spontaneous fission in 252Cf. The design and performance of this avalanche counter for targets with extreme α-decay rate up to ~2.4×108/s are described.

  15. A compact gas-filled avalanche counter for DANCE

    DOE PAGES

    Wu, C. Y.; Chyzh, A.; Kwan, E.; ...

    2012-08-04

    A compact gas-filled avalanche counter for the detection of fission fragments was developed for a highly segmented 4π γ-ray calorimeter, namely the Detector for Advanced Neutron Capture Experiments located at the Lujan Center of the Los Alamos Neutron Science Center. It has been used successfully for experiments with 235U, 238Pu,239Pu, and 241Pu isotopes to provide a unique signature to differentiate the fission from the competing neutron-capture reaction channel. We also used it to study the spontaneous fission in 252Cf. The design and performance of this avalanche counter for targets with extreme α-decay rate up to ~2.4×108/s are described.

  16. Impact damage on shielded gas-filled vessels

    NASA Astrophysics Data System (ADS)

    Schäfer, F.; Schneider, E.; Lambert, M.

    2001-10-01

    This paper gives a summary of the findings from impacts on shielded gas-filled cylindrical aluminium alloy (A12219 T851) and titanium alloy (Ti6A14V) pressure vessels that were performed at the Ernst-Mach-Institute in the frame of an ESA contract. The effect of impacts on shielded vessels with projectiles that have a kinetic energy close to the ballistic limit of the combined system of shield and vessel's front wall was investigated. The shields were single Al-bumper plates, unreinforced MLI and MLI reinforced with 2 layers of Betacloth. The threshold diameters that cause leakage from the vessel's front wall were determined experimentally as a function of shield material and shield spacing. For Al-shielded Al- and Ti-vessels, a safety design factor to avoid leakage is presented based on existing Whipple shield equations.

  17. Alteration of natural (37)Ar activity concentration in the subsurface by gas transport and water infiltration.

    PubMed

    Guillon, Sophie; Sun, Yunwei; Purtschert, Roland; Raghoo, Lauren; Pili, Eric; Carrigan, Charles R

    2016-05-01

    High (37)Ar activity concentration in soil gas is proposed as a key evidence for the detection of underground nuclear explosion by the Comprehensive Nuclear Test-Ban Treaty. However, such a detection is challenged by the natural background of (37)Ar in the subsurface, mainly due to Ca activation by cosmic rays. A better understanding and improved capability to predict (37)Ar activity concentration in the subsurface and its spatial and temporal variability is thus required. A numerical model integrating (37)Ar production and transport in the subsurface is developed, including variable soil water content and water infiltration at the surface. A parameterized equation for (37)Ar production in the first 15 m below the surface is studied, taking into account the major production reactions and the moderation effect of soil water content. Using sensitivity analysis and uncertainty quantification, a realistic and comprehensive probability distribution of natural (37)Ar activity concentrations in soil gas is proposed, including the effects of water infiltration. Site location and soil composition are identified as the parameters allowing for a most effective reduction of the possible range of (37)Ar activity concentrations. The influence of soil water content on (37)Ar production is shown to be negligible to first order, while (37)Ar activity concentration in soil gas and its temporal variability appear to be strongly influenced by transient water infiltration events. These results will be used as a basis for practical CTBTO concepts of operation during an OSI.

  18. Laser-plasma interactions in large gas-filled hohlraums

    SciTech Connect

    Turner, R.E.; Powers, L.V.; Berger, R.L.

    1996-06-01

    Indirect-drive targets planned for the National Ignition Facility (NIF) laser consist of spherical fuel capsules enclosed in cylindrical Au hohlraums. Laser beams, arranged in cylindrical rings, heat the inside of the Au wall to produce x rays that in turn heat and implode the capsule to produce fusion conditions in the fuel. Detailed calculations show that adequate implosion symmetry can be maintained by filling the hohlraum interior with low-density, low-Z gases. The plasma produced from the heated gas provides sufficient pressure to keep the radiating Au surface from expanding excessively. As the laser heats this gas, the gas becomes a relatively uniform plasma with small gradients in velocity and density. Such long-scale-length plasmas can be ideal mediums for stimulated Brillouin Scattering (SBS). SBS can reflect a large fraction of the incident laser light before it is absorbed by the hohlraum; therefore, it is undesirable in an inertial confinement fusion target. To examine the importance of SBS in NIF targets, the authors used Nova to measure SBS from hohlraums with plasma conditions similar to those predicted for high-gain NIF targets. The plasmas differ from the more familiar exploding foil or solid targets as follows: they are hot (3 keV); they have high electron densities (n{sub e}=10{sup 21}cm{sup {minus}3}); and they are nearly stationary, confined within an Au cylinder, and uniform over large distances (>2 mm). These hohlraums have <3% peak SBS backscatter for an interaction beam with intensities of 1-4 x 10{sup 15} W/cm{sup 2}, a laser wavelength of 0.351{micro}m, f/4 or f/8 focusing optics, and a variety of beam smoothing implementations. Based on these conditions the authors conclude that SBS does not appear to be a problem for NIF targets.

  19. Experimental Study of High-Z Gas Buffers in Gas-Filled ICF Engines

    SciTech Connect

    Rhodes, M A; Kane, J; Loosmore, G; DeMuth, J; Latkowski, J

    2010-12-03

    ICF power plants, such as the LIFE scheme at LLNL, may employ a high-Z, target-chamber gas-fill to moderate the first-wall heat-pulse due to x-rays and energetic ions released during target detonation. To reduce the uncertainties of cooling and beam/target propagation through such gas-filled chambers, we present a pulsed plasma source producing 2-5 eV plasma comprised of high-Z gases. We use a 5-kJ, 100-ns theta discharge for high peak plasma-heating-power, an electrode-less discharge for minimizing impurities, and unobstructed axial access for diagnostics and beam (and/or target) propagation studies. We will report on the plasma source requirements, design process, and the system design.

  20. Optimisation of the thickness of the moderator for positron annihilation process study in Ar gas

    NASA Astrophysics Data System (ADS)

    Oka, Toshitaka; Sano, Yosuke; Kino, Yasushi; Sekine, Tsutomu

    2014-06-01

    To investigate the deceleration and annihilation processes of positron in noble gas, we attempted to optimise the thickness of the positron moderator. The results of the decreasing trend of free positron intensity and ortho-positronium intensity with the thickness, and the annihilation rate suggest that the energy of almost all the positrons passed through the metal foils was much above the positronium formation threshold of 9 eV. Total thickness of 0.1 g cm-2 of the moderator and the Ar gas was required to stop almost all the positron in Ar gas.

  1. Genetic types of natural gas and filling patterns in Daniudi gas field, Ordos Basin, China

    NASA Astrophysics Data System (ADS)

    Liu, Quanyou; Jin, Zhijun; Meng, Qingqiang; Wu, Xiaoqi; Jia, Huichong

    2015-08-01

    The genetic types, source precursors and filling pattern of natural gas in the Upper Carboniferous Taiyuan Formation, Lower Permian Shanxi Formation and Lower Shihezi Formation gas reservoirs of Daniudi gas field were investigated using chemical composition as well as carbon and hydrogen isotopic compositions. Geochemical analysis of natural gases in 25 representative wells shows that natural gas in the Daniudi gas field is composed predominantly of hydrocarbons with a dryness coefficient of 0.884-0.978. The carbon isotopic values of ethane and propane are higher than -28‰ and -25‰, respectively, and the hydrogen isotopic values of methane are lower than -180‰, indicating that natural gas in the Daniudi field is a typical coal-type gas, derived mainly from humic organic matter in the transitional facies of the Carboniferous-Permian age. Hydrogen isotopic values of CH4 and H2 display a good positive correlation, suggesting that both were controlled by thermal maturity. When the mixing of ethane generated from mudstone and coal with the same kerogen type and similar thermal maturity occurred, the carbon isotopic values of ethane barely reflect the thermal maturity. Although the fractionation of hydrogen isotopes of ethane is significantly higher than that of carbon, hydrogen isotopic values of ethane in natural gas reservoirs evidently are not related to thermal maturity. The Daniudi natural gas reservoirs represent both self-sourced and near-source accumulations. The natural gas accumulations in the Late Triassic-Early Jurassic periods are mainly of the self-sourced type, while accumulations in the Late Jurassic-Early Cretaceous period comprise both self-sourced and near-source patterns, and the natural gas reservoirs formed after the Late Cretaceous period are mainly of the near-source type.

  2. A Concept for a Low Pressure Noble Gas Fill Intervention in the IFE Fusion Test Facility (FTF) Target Chamber

    SciTech Connect

    Gentile, C. A.; Blanchard, W. R.; Kozub, T. A.; Aristova, M.; McGahan, C.; Natta, S.; Pagdon, K.; Zelenty, J.

    2010-01-14

    wall acts as the primary heat exchanger. During removal, gas is pumped through the laser ports by turbo molecular-drag pumps (TM-DP). For the purpose of reducing organic based lubricants and seals, a magnetically levitated TM-DP is being investigated with pump manufacturers. Currently, magnetically levitated turbo molecular pumps are commercially available. The pumps will be exposed to thermal loads and ionizing radiation (tritium, Ar-41, post detonation neutrons). Although the TM-DP's will be subjected to these various radiations, current designs for similar pumping devices have been hardened and have the ability of locating control electronics in remote radiation shielded enclosures4. The radiation hardened TM-DP's will be 5 required to operate with minimal maintenance for periods of up to 18 continuous months. As part of this initial investigation for developing a conceptual engineering strategy for a gas fill solution, commercial suppliers of low pressure gas pumping systems have been contacted and engaged in this evaluation. Current technology in the area of mechanical pumping systems indicates that the development of a robust pumping system to meet the requirements of the FTF gas fill concept is within the limits of COTS equipment3,4.

  3. Simulations of indirectly driven gas-filled capsules at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Weber, S. V.; Casey, D. T.; Eder, D. C.; Kilkenny, J. D.; Pino, J. E.; Smalyuk, V. A.; Grim, G. P.; Remington, B. A.; Rowley, D. P.; Yeamans, C. B.; Tipton, R. E.; Barrios, M.; Benedetti, R.; Berzak Hopkins, L.; Bleuel, D. L.; Bond, E. J.; Bradley, D. K.; Caggiano, J. A.; Callahan, D. A.; Cerjan, C. J.; Clark, D. S.; Divol, L.; Edgell, D. H.; Edwards, M. J.; Eckart, M. J.; Fittinghoff, D.; Frenje, J. A.; Gatu-Johnson, M.; Glebov, V. Y.; Glenn, S.; Guler, N.; Haan, S. W.; Hamza, A.; Hatarik, R.; Herrmann, H.; Hoover, D.; Hsing, W. W.; Izumi, N.; Jones, O. S.; Kervin, M.; Khan, S.; Kline, J.; Knauer, J.; Kritcher, A.; Kyrala, G.; Landen, O. L.; Pape, S. Le; Ma, T.; Mackinnon, A. J.; MacPhee, A. G.; Marinak, M. M.; Mcnaney, J. M.; Meezan, N. B.; Merrill, F. E.; Mintz, M.; Moore, A.; Munro, D. H.; Nikroo, A.; Pak, A.; Parham, T.; Petrasso, R.; Rinderknecht, H. G.; Sayre, D. B.; Sepke, S. M.; Spears, B. K.; Stoeffl, W.; Tommasini, R.; Town, R. P.; Volegov, P.; Widmann, K.; Wilson, D. C.; Zylstra, A. B.

    2014-11-01

    Gas-filled capsules imploded with indirect drive on the National Ignition Facility have been employed as symmetry surrogates for cryogenic-layered ignition capsules and to explore interfacial mix. Plastic capsules containing deuterated layers and filled with tritium gas provide a direct measure of mix of ablator into the gas fuel. Other plastic capsules have employed DT or D3He gas fill. We present the results of two-dimensional simulations of gas-filled capsule implosions with known degradation sources represented as in modeling of inertial confinement fusion ignition designs; these are time-dependent drive asymmetry, the capsule support tent, roughness at material interfaces, and prescribed gas-ablator interface mix. Unlike the case of cryogenic-layered implosions, many observables of gas-filled implosions are in reasonable agreement with predictions of these simulations. Yields of TT and DT neutrons as well as other x-ray and nuclear diagnostics are matched for CD-layered implosions. Yields of DT-filled capsules are over-predicted by factors of 1.4-2, while D3He capsule yields are matched, as well as other metrics for both capsule types.

  4. Plasma parameters and active species kinetics in CF4/O2/Ar gas mixture: effects of CF4/O2 and O2/Ar mixing ratios

    NASA Astrophysics Data System (ADS)

    Lee, Junmyung; Kwon, Kwang-Ho; Efremov, A.

    2016-12-01

    The effects of both CF4/O2 and O2/Ar mixing ratios in three-component CF4/O2/Ar mixture on plasma parameters, densities and fluxes of active species determining the dry etching kinetics were analyzed. The investigation combined plasma diagnostics by Langmuir probes and zero-dimensional plasma modeling. It was found that the substitution of CF4 for O2 at constant fraction of Ar in a feed gas produces the non-monotonic change in F atom density, as it was repeatedly reported for the binary CF4/O2 gas mixtures. At the same time, the substitution of Ar for O2 at constant fraction of CF4 results in the monotonic increase in F atom density toward more oxygenated plasmas. The natures of these phenomena as well as theirs possible impacts on the etching/polymerization kinetics were discussed in details.

  5. A New Shallow Underground Gas-Proportional Counting Lab - First Results and Ar-37 Sensitivity

    SciTech Connect

    Aalseth, Craig E.; Day, Anthony R.; Fuller, Erin S.; Hoppe, Eric W.; Keillor, Martin E.; LaFerriere, Brian D.; Mace, Emily K.; Merriman, Jason H.; Myers, Allan W.; Overman, Cory T.; Panisko, Mark E.; Seifert, Allen; Warren, Glen A.; Williams, Richard M.

    2013-11-01

    Abstract A new ultra-low-background proportional counter was recently developed with an internal volume of 100 ml and has been characterized at pressures from 1-10 atmospheres with P-10 (90% Ar, 10% methane) gas. This design, along with a counting system providing event digitization and passive and active shielding, has been developed to complement a new shallow underground laboratory (30 meters water-equivalent). Backgrounds and low-level reference materials have been measured, and system sensitivity for Ar-37 has been calculated.

  6. Method and apparatus for producing gas-filled hollow spheres. [target pellets for inertial confinement fusion

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Elleman, D. D. (Inventor)

    1982-01-01

    A system for forming hollow spheres containing pressured gas is described which includes a cylinder device containing a molten solid material with a nozzle at its end. A second gas nozzle, lying slightly upstream from the tip of the first nozzle, is connected to a source that applies pressured filler gas that is to fill the hollow spheres. High pressure is applied to the molten metal, as by moving a piston within the cylinder device, to force the molten material out of the first nozzle. At the same time, pressured gas fills the center of the extruded hollow liquid pipe that breaks into hollow spheres. The environment outside the nozzles contains gas at a high pressure such as 100 atmospheres. Gas is supplied to the gas nozzle at a slightly higher pressure such as 101 atmospheres. The pressure applied to the molten material is at a still higher pressure such as 110 atmospheres.

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

    SciTech Connect

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

    2009-03-01

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

  8. Apparatus and methods for determining gas saturation and porosity of a formation penetrated by a gas filled or liquid filled borehole

    DOEpatents

    Wilson, Robert D.

    2001-03-27

    Methods and apparatus are disclosed for determining gas saturation, liquid saturation, porosity and density of earth formations penetrated by a well borehole. Determinations are made from measures of fast neutron and inelastic scatter gamma radiation induced by a pulsed, fast neutron source. The system preferably uses two detectors axially spaced from the neutron source. One detector is preferably a scintillation detector responsive to gamma radiation, and a second detector is preferably an organic scintillator responsive to both neutron and gamma radiation. The system can be operated in cased boreholes which are filled with either gas or liquid. Techniques for correcting all measurements for borehole conditions are disclosed.

  9. Gas-filled targets for large scalelength plasma interaction experiments on Nova

    SciTech Connect

    Powers, L.V.; Berger, R.L.; Munro, D.H.

    1994-11-01

    Stimulated Brillouin backscatter from large scale length gas-filled targets has been measured on Nova. These targets were designed to approximate conditions in indirect drive ignition target designs in underdense plasma electron density (n{sub e}{approximately}10{sup 21}/cm{sup 3}), temperature (T{sub e}>3 keV), and gradient scale lengths (L{sub n}{approximately} mm, L{sub v}>6 mm) as well as calculated gain for stimulated Brillouin scattering (SBS). The targets used in these experiments were gas-filled balloons with polyimide walls (gasbags) and gas-filled hohlraums. Detailed characterization using x-ray imaging and x-ray and optical spectroscopy verifies that the calculated plasma conditions are achieved. Time-resolved SBS backscatter from these targets is <3% for conditions similar to ignition target designs.

  10. DUV ArF light source automated gas optimization for enhanced repeatability and availability

    NASA Astrophysics Data System (ADS)

    Aggarwal, Tanuj; O'Brien, Kevin

    2015-03-01

    The need for repeatable, reliable, and faster DUV ArF light source gas optimizations drove the development of Automated Gas Optimization (AGO). These automate the manual gas optimization procedure previously used to select the laser chamber gas pressures and in addition, bandwidth actuation settings, to deliver consistent performance and long gas lives, while maintaining stability and bounds on laser inputs. Manual gas optimization procedure requires at least two refills and an on-site visit by service personnel that can take over an hour to complete. This results in inconsistent light source performance, and sometimes unscheduled downtime. The key to AGO technology is the real-time estimation and monitoring of the laser's gas and bandwidth states, and automatic adjustment of gas pressure and bandwidth actuators until the states reach their specified targets, thus creating a closed loop. AGO executes on every refill, typically complete in less than 5 minutes, and collect performance data to allow long-term trending. They include built-in safety features and flexibility to allow future upgrades of light source features or performance tuning. Deployed in many lasers in the field, AGO has proved to be a dependable automation, yielding repeatable, fast, and reliable optimizations and valuable long-term trending data used to assess chamber performance

  11. Detection of a noble gas molecular ion, 36ArH+, in the Crab Nebula.

    PubMed

    Barlow, M J; Swinyard, B M; Owen, P J; Cernicharo, J; Gomez, H L; Ivison, R J; Krause, O; Lim, T L; Matsuura, M; Miller, S; Olofsson, G; Polehampton, E T

    2013-12-13

    Noble gas molecules have not hitherto been detected in space. From spectra obtained with the Herschel Space Observatory, we report the detection of emission in the 617.5- and 1234.6-gigahertz J = 1-0 and 2-1 rotational lines of (36)ArH(+) at several positions in the Crab Nebula, a supernova remnant known to contain both molecular hydrogen and regions of enhanced ionized argon emission. Argon-36 is believed to have originated from explosive nucleosynthesis in massive stars during core-collapse supernova events. Its detection in the Crab Nebula, the product of such a supernova event, confirms this expectation. The likely excitation mechanism for the observed (36)ArH(+) emission lines is electron collisions in partially ionized regions with electron densities of a few hundred per centimeter cubed.

  12. Detection of a Noble Gas Molecular Ion, 36ArH+, in the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Barlow, M. J.; Swinyard, B. M.; Owen, P. J.; Cernicharo, J.; Gomez, H. L.; Ivison, R. J.; Krause, O.; Lim, T. L.; Matsuura, M.; Miller, S.; Olofsson, G.; Polehampton, E. T.

    2013-12-01

    Noble gas molecules have not hitherto been detected in space. From spectra obtained with the Herschel Space Observatory, we report the detection of emission in the 617.5- and 1234.6-gigahertz J = 1-0 and 2-1 rotational lines of 36ArH+ at several positions in the Crab Nebula, a supernova remnant known to contain both molecular hydrogen and regions of enhanced ionized argon emission. Argon-36 is believed to have originated from explosive nucleosynthesis in massive stars during core-collapse supernova events. Its detection in the Crab Nebula, the product of such a supernova event, confirms this expectation. The likely excitation mechanism for the observed 36ArH+ emission lines is electron collisions in partially ionized regions with electron densities of a few hundred per centimeter cubed.

  13. Automatic external filling for the ion source gas bottle of a Van de Graaff accelerator

    NASA Astrophysics Data System (ADS)

    Strivay, D.; Bastin, T.; Dehove, C.; Dumont, P. D.; Marchal, A.; Garnir, H.; Weber, G.

    1997-09-01

    We describe a fully automatic system we developed to fill, from an external gas bottle, the ion source terminal gas storage bottle of a 2 MV Van de Graaff accelerator without depressing the 25 bar insulating gas. The system is based on a programmable automate ordering electropneumatical valves. The only manual operation is the connection of the external gas cylinder. The time needed for a gas change is reduced to typically 15 min (depending on the residual pressure wished for the gas removed from the terminal bottle). To check this system we study the ionic composition of the ion beam delivered by our accelerator after different gas changes. The switching magnet of our accelerator was used to analyse the ionic composition of the accelerated beams in order to verify the degree of elimination of the previous gases in the system.

  14. Origin of marine sour natural gas and gas-filling model for the Wolonghe Gas Field, Sichuan Basin, China

    NASA Astrophysics Data System (ADS)

    Liu, Quanyou; Jin, Zhijun; Li, Jian; Hu, Anping; Bi, Changchun

    2012-09-01

    The chemical and isotopic composition of natural gases from the Wolonghe Gas Field, Sichuan Basin, Southwest China, was investigated to assess the potential gas sources and reconstruct the gas-filling history of the reservoirs. All natural gases in this field are dominated by gaseous hydrocarbons (C1-C3) with varied amounts of non-hydrocarbon components (CO2, H2S and N2). The H2S content varies with reservoir intervals. It ranges from zero to 1.84% with an average of 0.37% in the Carboniferous reservoir, from 0.05% to 0.76% with an average of 0.30% in the Permian reservoir, and from 1.09% to 18.83% with an average of 5.39% in the Lower Triassic reservoir. The gas dryness coefficient (C1/C1-3) ranges from 0.97 to 1.0 with an average of 0.99. The carbon isotopic compositions of methane and its homologues in the Wolonghe Gas Field vary widely, with δ13C1 ⩾ δ13C2 < δ13C3 in the Carboniferous and Permian gas reservoirs, and δ13C1 < δ13C2 < δ13C3 in the Lower Triassic Jialingjiang Formation gas reservoirs. The δD1 values range from -140‰ to -100‰, with an average of -124.5‰. The δ34SH2S values in the field extend from 5.7‰ to 31.0‰, with δ34SH2S values in the Lower Triassic Jialingjiang Formation reservoirs being much higher than those in the Carboniferous and Permian reservoirs. The sour natural gases in the field originated from cracking of oil and were sourced from the marine sapropelic organic matter at high maturity levels. The natural gases underwent alteration by thermochemical sulfate reduction (TSR). Although the limited extent TSR occurred in the Carboniferous and Permian gas reservoirs, the TSR alteration is likely to have caused the high gas dryness and the 13C enrichment of CH4. The present low content of H2S in the Carboniferous and Permian gases would be related to the loss of H2S dissolved in water under the reconstruction of these gas reservoirs. In contrast, the high H2S in the Jialingjiang Formation gases is determined by both the

  15. Evaluation of Gas-filled Ionization Chamber Method for Radon Measurement at Two Reference Facilities

    SciTech Connect

    Ishikawa, Tetsuo; Tokonami, Shinji; Kobayashi, Yosuke; Sorimachi, Atsuyuki; Yatabe, Yoshinori; Miyahara, Nobuyuki

    2008-08-07

    For quality assurance, gas-filled ionization chamber method was tested at two reference facilities for radon calibration: EML (USA) and PTB (Germany). Consequently, the radon concentrations estimated by the ionization chamber method were in good agreement with the reference radon concentrations provided by EML as well as PTB.

  16. Effects of plasma physics on capsule implosions in gas-filled hohlraums

    SciTech Connect

    Lindman, E.L.; Delamater, N.D.; Magelssen, G.R.; Hauer, A.

    1994-10-01

    Initial experiments on capsule implosions in gas-filled hohlraums have been carried out on the NOVA Laser at Lawrence Livermore National Laboratory. Observed capsule shapes from preliminary experiments are more oblate than predicted. Improvements in modeling required to calculate these experiments and additional experiments are being pursued.

  17. Noble gas composition and 40Ar/39Ar age in eclogites from the main hole of the Chinese Continental Scientific Drilling project

    NASA Astrophysics Data System (ADS)

    Hopp, Jens; Schwarz, Winfried H.; Trieloff, Mario; Meyer, Hans-Peter; Hanel, Michael; Altherr, Rainer

    2016-10-01

    We present the first comprehensive noble gas study on eclogites. The four eclogite samples were recovered during the Chinese Continental Scientific Drilling and are from two distinct profile depth sections differing in their degree of interaction with meteoric water, based on their δ 18O-values (surface related and of mantle-type). Hence, noble gas analyses offer the potential to further discriminate between shallow (meteoric) and deep (mantle) fluid sources. Noble gas compositions reveal typical crustal fluid compositions, characterized by a variable mixture of atmospheric gases with significant contributions of nucleogenic neon, radiogenic 4He*, radiogenic 40Ar*, fissiogenic 131-136Xe, and presumably bariogenic 131Xe, but no significant addition of mantle gases. This signature can be also considered to represent one endmember component of eclogitic diamonds. Concentrations of non-radiogenic noble gases are rather low, with depletion of light relative to the heavier noble gases. Eclogites from lower depth which experienced a higher degree of interaction with meteoric water also showed higher contributions of atmospheric gas compared with eclogites recovered from greater depth. This is interpreted to result from interaction with high-salinity fluids during ultrahigh pressure (UH P). It demonstrates that the atmospheric noble gas abundance is a proxy for interaction with surface related fluids. 40Ar/39Ar (inverse) isochron ages of two phengite separates (241.2 ± 0.4 Ma and 275.0 ± 1.8 Ma, 1 σ-errors) predate the main phase of UH P metamorphism (ca. 220 Ma). Biotite yields an integrated age of about 1100 Ma. These age values are interpreted to reflect the likely addition of excess 40Ar without any chronological meaning.

  18. Gas-Filled Panels: An update on applications in the building thermal envelope

    SciTech Connect

    Griffith, B.T.; Arasteh, D.; Tuerler, D.

    1995-10-01

    This paper discusses the application of Gas-Filled Panels to the building thermal envelope. Gas-Filled Panels, or GFPs, are thermal insulating devices that retain a high concentration of a low- conductivity gas, at atmospheric pressure, within a multilayer infrared reflective baffle. The thermal performance of the panel depends on the type of gas fill and the baffle configuration. Heat- flow meter apparatus measurements have shown effective apparent thermal conductivities of 0.194 Btu{center_dot}in/h{center_dot}ft{sup 2}{center_dot}{degree}F with air as the gas fill, 0.138 Btu{center_dot}in/h{center_dot}ft{sup 2}{center_dot}{degree}F with argon, and 0.081 Btu{center_dot}in/h{center_dot}ft{sup 2}{center_dot}{degree}F with krypton. Calorimetric measurements have also shown total resistance levels of about R-12.6 h{center_dot}ft{sup 2}{center_dot}{degree}F/Btu for a 1.0-inch thick krypton panel, R-25.7 h{center_dot}ft{sup 2}{center_dot}{degree}F/Btu for a 2.0-inch krypton panel, and R-18.4 f{center_dot}ft{sup 2}{center_dot}{degree}F/Btu for a 10-inch xenon panel. GFPs are flexible, self-supporting and can be made in a variety of shapes and sizes to thoroughly fill most types of cavities in building walls and roofs, although the modular nature of the panels can lead to complications in installing them, especially for irregularly shaped cavities. We present computer simulation results showing the improvement in thermal resistance resulting from using an argon-GFP in place of glass fiber batt insulation in wood-frame construction. This report also presents estimates of the quantity and cost of material components needed to manufacture GFPs using current prototype designs.

  19. Shock formation in Ne, Ar, Kr, and Xe on DD gas puff implosions

    NASA Astrophysics Data System (ADS)

    Narkis, J.; Rahman, H. U.; Wessel, F. J.; Ney, P.; Beg, F.

    2016-10-01

    1- and 2-D simulations of a 1-cm radius, gas-puff implosion of Ne, Ar, Kr, and Xe liners onto a DD target are conducted using the discharge parameters for the Univ. Nevada, Reno, Zebra (1 MA, 125 ns) voltage driver and the resistive MHD code MACH2. During the run-in phase, initial†shock heating preheats the DD plasma, with subsequent stable, adiabatic compression heating the target to high energy density. The dynamics of the former in both the liner and target are investigated. It is shown that magnetic field transport to the liner/target interface does not occur prior to the run-in phase in Ne and Ar liners, yet does occur in Kr and Xe liners, and that magnetic field transport to the interface is a requirement for shock initiation, thus demonstrating the necessity for using a high-Z material in the Staged Z-pinch. Shock reflection off the axis and subsequent collision with the interface results in partial transmission into the liner, which manifests as current reversal, and consequently an enhanced Bθ gradient. 2-D simulations show that magneto-Rayleigh-Taylor instability growth decreases with increasing Z, with shock formation providing sufficient isolation to reproduce the current reversal and enhanced Bθ gradient observed in 1-D simulations. Advanced Research Projects Agency - Energy, DE-AR0000569.

  20. Utilizing Gas Filled Cavities for the Generation of an Intense Muon Source

    SciTech Connect

    Stratakis, Diktys; Neuffer, David V.

    2015-05-01

    A key requirement for designing intense muon sources is operating rf cavities in multi-tesla magnetic fields. Recently, a proof-of-principle experiment demonstrated that an rf cavity filed with high pressure hydrogen gas could meet this goal. In this study, rigorous simulation is used to design and evaluate the performance of an intense muon source with gas filled cavities. We present a new lattice design and compare our results with conventional schemes. We detail the influence of gas pressure on the muon production rate.

  1. Utilizing gas-filled cavities for the generation of an intense muon source

    SciTech Connect

    Stratakis, Diktys; Neuffer, David V.

    2015-05-03

    A key requirement for designing intense muon sources is operating rf cavities in multi-tesla magnetic fields. Recently, a proof-of-principle experiment demonstrated that an rf cavity filed with high pressure hydrogen gas could meet this goal. In this study, rigorous simulation is used to design and evaluate the performance of an intense muon source with gas filled cavities. We present a new lattice design and compare our results with conventional schemes. We detail the influence of gas pressure on the muon production rate.

  2. Potential interstellar noble gas molecules: ArOH+ and NeOH+ rovibrational analysis from quantum chemical quartic force fields

    NASA Astrophysics Data System (ADS)

    Theis, Riley A.; Fortenberry, Ryan C.

    2016-03-01

    The discovery of ArH+ in the interstellar medium has shown that noble gas chemistry may be of more chemical significance than previously believed. The present work extends the known chemistry of small noble gas molecules to NeOH+ and ArOH+. Besides their respective neonium and argonium diatomic cation cousins, these hydroxyl cation molecules are the most stable small noble gas molecules analyzed of late. ArOH+ is once again more stable than the neon cation, but both are well-behaved enough for a complete quartic force field analysis of their rovibrational properties. The Ar-O bond in ArOH+ , for instance, is roughly three-quarters of the strength of the Ar-H bond in ArH+ highlighting the rigidity of this system. The rotational constants, geometries, and vibrational frequencies for both molecules and their various isotopologues are computed from ab initio quantum chemical theory at high-level, and it is shown that these cations may form in regions where peroxy or weakly-bound alcohols may be present. The resulting data should be of significant assistance for the laboratory or observational analysis of these potential interstellar molecules.

  3. Hydrogen gas filling into an actual tank at high pressure and optimization of its thermal characteristics

    NASA Astrophysics Data System (ADS)

    Khan, Md. Tawhidul Islam; Monde, Masanori; Setoguchi, Toshiaki

    2009-09-01

    Gas with high pressure is widely used at present as fuel storage mode for different hydrogen vehicles. Different types of materials are used for constructing these hydrogen pressure vessels. An aluminum lined vessel and typically carbon fiber reinforced plastic (CFRP) materials are commercially used in hydrogen vessels. An aluminum lined vessel is easy to construct and posses high thermal conductivity compared to other commercially available vessels. However, compared to CFRP lined vessel, it has low strength capacity and safety factors. Therefore, nowadays, CFRP lined vessels are becoming more popular in hydrogen vehicles. Moreover, CFRP lined vessel has an advantage of light weight. CFRP, although, has many desirable properties in reducing the weight and in increasing the strength, it is also necessary to keep the material temperature below 85 °C for maintaining stringent safety requirements. While filling process occurs, the temperature can be exceeded due to the compression works of the gas flow. Therefore, it is very important to optimize the hydrogen filling system to avoid the crossing of the critical limit of the temperature rise. Computer-aided simulation has been conducted to characterize the hydrogen filling to optimize the technique. Three types of hydrogen vessels with different volumes have been analyzed for optimizing the charging characteristics of hydrogen to test vessels. Gas temperatures are measured inside representative vessels in the supply reservoirs (H2 storages) and at the inlet to the test tank during filling.

  4. High pressure laser plasma studies. [energy pathways in He-Ar gas mixtures at low pressure

    NASA Technical Reports Server (NTRS)

    Wells, W. E.

    1980-01-01

    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.

  5. Wide-field laser ophthalmoscopy for imaging of gas-filled eyes after macular hole surgery

    PubMed Central

    Nakao, Shintaro; Arita, Ryoichi; Sato, Yuki; Enaida, Hiroshi; Ueno, Akifumi; Matsui, Takaaki; Salehi-Had, Hani; Ishibashi, Tatsuro; Sonoda, Koh-hei

    2016-01-01

    Background and objective Existing ophthalmoscopy methods are unable to obtain clear fundus autofluorescence (FAF) images in gas-filled eyes. The purpose of this study was to evaluate the capability of wide-field laser ophthalmoscopy (Optos) in obtaining FAF images in gas-filled eyes for the assessment of macular hole (MH) closure after surgery. Methods This was an interventional case series. Eighteen consecutive patients with unilateral MH underwent vitrectomy with internal limiting membrane peeling and 20% sulfur hexafluoride gas tamponade. FAF images using Optos were recorded preoperatively and postoperatively (days 1, 2, and 7). Results On postoperative days 1, 2, and 7, FAF images were obtained from 11/18 (61.1%), 9/18 (50.0%), and 17/18 eyes (94.4%), respectively, using Optos. The quality of FAF images using Optos was sufficient to determine MH closure in 9/18 (50.0%) of gas-filled eyes postoperatively. Quantitative analysis of FAF images was helpful in determining complete or partial closure of the MH. Conclusion FAF imaging using Optos might be a useful adjunct to optical coherence tomography as a supportive method to guide the release from facedown posturing in some cases of MH. PMID:27601877

  6. High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

    SciTech Connect

    Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

    2015-04-15

    A recent low gas-fill density (0.6 mg/cc {sup 4}He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc {sup 4}He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

  7. Hydro-Coupling Effects on Compression Symmetry in Gas-Filled Hohlraum Experiments at the Omega Laser

    SciTech Connect

    Dewalds, E L; Pollaine, S W; Landen, O L; Amendt, P A; Turner, R E; Wallace, R; Campbell, K M; Glenzer, S H

    2003-08-26

    Ignition hohlraum designs use low Z gas fill to slow down the inward progress of high Z ablated plasma from the hohlraum walls preventing large laser spot motion and capsule drive asymmetries. In order to optimize the ignition design, the gas hydro-coupling effect to a fusion capsule asymmetry is presently being assessed in experiments at the Omega laser facility with gas filled hohlraums and foam balls. Our experiments measure the effects of the pressure spike that is generated by direct gas heating by the drive laser beams on the capsule surrogate for various hohlraum gas fill densities (0-2.5 mg/cc). To isolate the effect of the gas-hydro coupling pressure, we have begun by using plastic ''hohlraums'' to reduce the x-ray ablation pressure. The foam ball images measured by x-ray backlighting show increasing pole-hot pressure asymmetry for increasing gas pressure. In addition, the gas hydrodynamics is studied by imaging of a low concentration Xe gas fill dopant. The gas fill self-emission. shows the early pressure spike and its propagation towards the foam ball, as well as the gas stagnation on the holraum axis at later times, both contributing to the capsule asymmetry. These first gas hydro-coupling results are compared to LASNEX simulations.

  8. Numerical Simulation of Debris Cloud Propagation inside Gas-Filled Pressure Vessels under Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Gai, F. F.; Pang, B. J.; Guan, G. S.

    2009-03-01

    In the paper SPH methods in AUTODYN-2D is used to investigate the characteristics of debris clouds propagation inside the gas-filled pressure vessels for hypervelocity impact on the pressure vessels. The effect of equation of state on debris cloud has been investigated. The numerical simulation performed to analyze the effect of the gas pressure and the impact condition on the propagation of the debris clouds. The result shows that the increase of gas pressure can reduce the damage of the debris clouds' impact on the back wall of vessels when the pressure value is in a certain range. The smaller projectile lead the axial velocity of the debris cloud to stronger deceleration and the debris cloud deceleration is increasing with increased impact velocity. The time of venting begins to occur is related to the "vacuum column" at the direction of impact-axial. The paper studied the effect of impact velocities on gas shock wave.

  9. Differentiated muscles are mandatory for gas-filling of the Drosophila airway system

    PubMed Central

    Wang, Yiwen; Cruz, Tina; Irion, Uwe; Moussian, Bernard

    2015-01-01

    ABSTRACT At the end of development, organs acquire functionality, thereby ensuring autonomy of an organism when it separates from its mother or a protective egg. In insects, respiratory competence starts when the tracheal system fills with gas just before hatching of the juvenile animal. Cellular and molecular mechanisms of this process are not fully understood. Analyses of the phenotype of Drosophila embryos with malformed muscles revealed that they fail to gas-fill their tracheal system. Indeed, we show that major regulators of muscle formation like Lame duck and Blown fuse are important, while factors involved in the development of subsets of muscles including cardiac and visceral muscles are dispensable for this process, suggesting that somatic muscles (or parts of them) are essential to enable tracheal terminal differentiation. Based on our phenotypic data, we assume that somatic muscle defect severity correlates with the penetrance of the gas-filling phenotype. This argues that a limiting molecular or mechanical muscle-borne signal tunes tracheal differentiation. We think that in analogy to the function of smooth muscles in vertebrate lungs, a balance of physical forces between muscles and the elasticity of tracheal walls may be decisive for tracheal terminal differentiation in Drosophila. PMID:26621831

  10. Shock formation in Ne, Ar, Kr, and Xe on deuterium gas puff implosions

    SciTech Connect

    Narkis, J.; Rahman, H. U.; Ney, P.; Desjarlais, M. P.; Wessel, F. J.; Conti, F.; Valenzuela, J. C.; Beg, F. N.

    2016-12-29

    1- and 2-D simulations of 1-cm radius, gas-puff liners of Ne, Ar, Kr, and Xe imploding onto a deuterium target are conducted using the discharge parameters for the Zebra (1 MA, 130 ns) driver using the resistive MHD code MACH2. This is an implementation of the Staged Z-pinch concept, in which the target is driven to high-energy-density first by shock compression launched by a diffused azimuthal magnetic field (J×B force), and then by the adiabatic compression as the liner converges on axis. During the run-in phase, the initial shock heating preheats the deuterium plasma, with a subsequent stable, adiabatic compression heating the target to high energy density. Shock compression of the target coincides with the development of a J×B force at the target/liner interface. Stronger B-field transport and earlier shock compression increases with higher-Z liners, which results in an earlier shock arrival on axis. As a result, delayed shock formation in lower-Z liners yields a relative increase in shock heating, however, the 2-D simulations show an increased target isolation from magneto-Rayleigh-Taylor instability penetration, suggesting that an optimal balance between these two effects is reached in an Ar or Kr liner, rather than with Xe.

  11. Shock formation in Ne, Ar, Kr, and Xe on deuterium gas puff implosions

    DOE PAGES

    Narkis, J.; Rahman, H. U.; Ney, P.; ...

    2016-12-29

    1- and 2-D simulations of 1-cm radius, gas-puff liners of Ne, Ar, Kr, and Xe imploding onto a deuterium target are conducted using the discharge parameters for the Zebra (1 MA, 130 ns) driver using the resistive MHD code MACH2. This is an implementation of the Staged Z-pinch concept, in which the target is driven to high-energy-density first by shock compression launched by a diffused azimuthal magnetic field (J×B force), and then by the adiabatic compression as the liner converges on axis. During the run-in phase, the initial shock heating preheats the deuterium plasma, with a subsequent stable, adiabatic compressionmore » heating the target to high energy density. Shock compression of the target coincides with the development of a J×B force at the target/liner interface. Stronger B-field transport and earlier shock compression increases with higher-Z liners, which results in an earlier shock arrival on axis. As a result, delayed shock formation in lower-Z liners yields a relative increase in shock heating, however, the 2-D simulations show an increased target isolation from magneto-Rayleigh-Taylor instability penetration, suggesting that an optimal balance between these two effects is reached in an Ar or Kr liner, rather than with Xe.« less

  12. Simulations of Ar gas-puff implosions on Z with a Xe dopant

    NASA Astrophysics Data System (ADS)

    Tangri, Varun; Giuliani, J. L.; Velikovich, A. L.; Ouart, N. D.; Dasgupta, A.; Thornhill, J. W.; Apruzese, J. P.; Harvey-Thompson, A. J.; Jones, B.; Jennings, C. A.

    2016-10-01

    A recent experiment on the Z machine at SNL indicated that the presence of a small fraction of Xe (0.8% by number in the center jet) in a Ar gas puff shot had a significant effect on the emitted K-shell radiation. In presence of the Xe dopant, the Ar K-shell yield dramatically reduced from 373 +/-9 to 129 +/-9 kJ. The peak K-shell power was also significantly lower and accompanied by two nearly equal peaks. A second shot without the Xe dopant consisted of a single peak. We present radiation-magnetohydrodynamic simulations of these shots [Z2603 (with Xe) and Z2605 (without Xe)] using the using the Mach2-TCRE code with a tabulated collisional radiative equilibrium model. Detailed numerical simulations exploring the impact of the Xe dopant on the implosion dynamics and the resultant K-shell radiation will be presented. Analysis of a time- and space resolved synthetic K-shell spectra would also be presented. Work supported by the DOE/NNSA. SNL is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's NNSA under contract DE-AC04-94AL85000.

  13. Transmucosal gas-loss rates in middle ears initially filled with O2 or CO2.

    PubMed

    Kania, Romain E; Vérillaud, Benjamin; Ars, Bernard; Tran Ba Huy, Patrice; Herman, Philippe; Ar, Amos

    2016-10-01

    This study investigates the role of different gases in clearance of gas in the middle ear cavity (ME) by its mucosal blood flow. A rat model was used to measure gas volume changes in the ME cavity at constant pressure without ventilation. We disturbed the normal gas composition of the ME by filling it with O2 or CO2, measured the consequent changes in gas volume over time and compared these results with previously obtained ones for air and N2. The first 5 min of the primary transient phase (phase I) for O2 or CO2 was characterized by a volume loss decrease of -0.49 ± 0.34 μL and -46.28 ± 8.49 μL, respectively, with volume loss increase for air and N2 differing greatly, at +0.17 ± 0.17 and +2.31 ± 0.81, respectively. The CO2 value of -46.28 μL showed that a volume of gas equivalent to that of the ME cleft volume was eliminated within the first 5 min. In the second phase (phase II), all gases showed a linear decrease in volume, which presumably represents a steady-state gas loss rate. However, the gas loss rate of -0.307 ± 0.170 μL min(-1) for O2-filled MEs was significantly higher than the mean of -0.124 μL min(-1) for all other gases. We used a previously established mathematical model to calculate the effective ME mucosal blood flow rate under steady-state (phase II) conditions. The blood flow results for O2-filled MEs differed greatly from those of the other gases (89.0 ± 49.28 vs. 26.5 μL min(-1), on average), which suggest that the model used to calculate blood flow should be modified if used with O2-filled MEs. Further work should involve a comparison of our method with different methods to verify ME blood flow rate.

  14. Investigating the effect of adding an on-axis jet to Ar gas puff Z pinches on Z.

    DOE PAGES

    Harvey-Thompson, Adam James; Jennings, Christopher Ashley; Jones, Brent M.; ...

    2016-10-20

    Double-shell Ar gas puff implosions driven by 16.5±0.5 MA on the Z generator at Sandia National Laboratories are very effective emitters of Ar K-shell radiation (photon energy >3 keV), producing yields of 330 ± 9% kJ (B. Jones et al., Phys. Plasmas, 22, 020706, 2015). In addition, previous simulations and experiments have reported dramatic increases in K-shell yields when adding an on-axis jet to double shell gas puffs for some configurations.

  15. Anisotropic amplitude variation of the bottom-simulating reflector beneath fracture-filled gas hydrate deposit

    NASA Astrophysics Data System (ADS)

    Sriram, G.; Dewangan, P.; Ramprasad, T.; Rama Rao, P.

    2013-05-01

    the first time, we report the amplitude variation with angle (AVA) pattern of bottom-simulating reflectors (BSRs) beneath fracture-filled gas hydrate deposits when the effective medium is anisotropic. The common depth point (CDP) gathers of two mutually perpendicular multichannel seismic profiles, located in the vicinity of Site NGHP-01-10, are appropriately processed such that they are fit for AVA analysis. AVA analysis of the BSR shows normal-incidence reflection coefficients of -0.04 to -0.11 with positive gradients of 0.04 to 0.31 indicating class IV pattern. The acoustic properties from isotropic rock physics model predict class III AVA pattern which cannot explain the observed class IV AVA pattern in Krishna-Godavari basin due to the anisotropic nature of fracture-filled gas hydrate deposits. We modeled the observed class IV AVA of the BSR by assuming that the gas hydrate bearing sediment can be represented by horizontally transversely isotropic (HTI) medium after accounting for anisotropic wave propagation effects on BSR amplitudes. The effective medium properties are estimated using Backus averaging technique, and the AVA pattern of BSRs is modeled using the properties of overlying HTI and underlying isotropy/HTI media with or without free gas. Anisotropic AVA analysis of the BSR from the inline seismic profile shows 5-30% gas hydrate concentration (equivalent to fracture density) and the azimuth of fracture system (fracture orientation) with respect to the seismic profile is close to 45°. Free gas below the base of gas hydrate stability zone is interpreted in the vicinity of fault system (F1).

  16. Impact of Filling Gas on Subharmonic Emissions of Phospholipid Ultrasound Contrast Agents.

    PubMed

    Kanbar, Emma; Fouan, Damien; Sennoga, Charles A; Doinikov, Alexander A; Bouakaz, Ayache

    2017-02-14

    Subharmonic signals backscattered from gas-filled lipid-shelled microbubbles have generated significant research interest because they can improve the detection and sensitivity of contrast-enhanced ultrasound imaging. However, the emission of subharmonic signals is strongly characterized by a temporal dependence, the origins of which have not been sufficiently elucidated. The features that influence subharmonic emissions need to be identified not only to better develop next-generation microbubble contrast agents, but also to develop more efficient subharmonic imaging (SHI) modes and therapeutic strategies. We examined the effect of microbubble filling gas on subharmonic emissions. Phospholipid shelled-microbubbles with different gaseous compositions such as sulfur hexafluoride (SF6), octafluoropropane (C3F8) or decafluorobutane (C4F10), nitrogen (N2)/C4F10 or air were insonated using a driving frequency of 10 MHz and peak negative pressure of 450 kPa, and their acoustic responses were tracked by monitoring both second harmonic and subharmonic emissions. Microbubbles were first acoustically characterized with their original gas and then re-characterized after substitution of the original gas with air, SF6 or C4F10. A measureable change in intensity of the subharmonic emissions with a 20- to 40-min delayed onset and increasing subharmonic emissions of the order 12-18 dB was recorded for microbubbles filled with C4F10. Substitution of C4F10 with air eliminated the earlier observed delay in subharmonic emissions. Significantly, substitution of SF6 for C4F10 successfully triggered a delay in the subharmonic emissions of the resultant agents, whereas substitution of C4F10 for SF6 eliminated the earlier observed suppression of subharmonic emissions, clearly suggesting that the type of filling gas contained in the microbubble agent influences subharmonic emissions in a time-dependent manner. Because our agents were dispersed in air-stabilized phosphate-buffered saline

  17. Thermal diode in gas-filled nanogap with heterogeneous surfaces using nonequilibrium molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Avanessian, T.; Hwang, G.

    2016-10-01

    A thermal diode serves as a basic building block to design advanced thermal management systems in energy-saving applications. However, the main challenges of existing thermal diodes are poor steady-state performance, slow transient response, and/or extremely difficult manufacturing. In this study, the thermal diode is examined by employing an argon gas-filled nanogap with heterogeneous surfaces in the Knudsen regime, using nonequilibrium molecular dynamics simulation. The asymmetric gas pressure and thermal accommodation coefficients changes are found due to asymmetric adsorptions onto the heterogeneous nanogap with respect to the different temperature gradient directions, and these in turn result in the thermal diode. The maximum degree of diode (or rectification) is Rmax ˜ 7, at the effective gas-solid interaction ratio between the two surfaces of ɛ*= 0.75. This work could pave the way to designing advanced thermal management systems such as thermal switches (transistors).

  18. Fluid hammer with gas desorption in a liquid-filling tube: experiments with three different liquids

    NASA Astrophysics Data System (ADS)

    Lema, Marcos; Peña, Fernando López; Rambaud, Patrick; Buchlin, Jean-Marie; Steelant, Johan

    2015-09-01

    The opening of a fast valve followed by a fluid line with a closed end generates a fluid hammer that may involve several multiphase phenomena. This is the case of the propulsion systems in satellites during the priming operation, where the lines are initially kept under vacuum conditions. The filling with liquid propellant is done by opening a pyrotechnic valve, and the fluid hammer taking place involves cavitation and gas desorption. For this purpose, an experimental study is carried out with inert fluids modeling a liquid propulsion system, where the saturation level of the test liquid is controlled, allowing to run experiments under deaerated and saturated conditions. The results show that the fluid hammer phenomenon is affected by the gas saturation conditions if the liquid is susceptible to high desorption rate. In this case, the desorbed pressurant gas in the lines cushions the liquid front impact at the closed ends, leading to a lower pressure rise during fluid hammer occurrence.

  19. Simulation of beam-induced plasma in gas-filled rf cavities

    NASA Astrophysics Data System (ADS)

    Yu, Kwangmin; Samulyak, Roman; Yonehara, Katsuya; Freemire, Ben

    2017-03-01

    Processes occurring in a radio-frequency (rf) cavity, filled with high pressure gas and interacting with proton beams, have been studied via advanced numerical simulations. Simulations support the experimental program on the hydrogen gas-filled rf cavity in the Mucool Test Area (MTA) at Fermilab, and broader research on the design of muon cooling devices. space, a 3D electromagnetic particle-in-cell (EM-PIC) code with atomic physics support, was used in simulation studies. Plasma dynamics in the rf cavity, including the process of neutral gas ionization by proton beams, plasma loading of the rf cavity, and atomic processes in plasma such as electron-ion and ion-ion recombination and electron attachment to dopant molecules, have been studied. Through comparison with experiments in the MTA, simulations quantified several uncertain values of plasma properties such as effective recombination rates and the attachment time of electrons to dopant molecules. Simulations have achieved very good agreement with experiments on plasma loading and related processes. The experimentally validated code space is capable of predictive simulations of muon cooling devices.

  20. DoD’s Compressed Natural Gas Filling Station in Afghanistan: An Ill-conceived $43 Million Project

    DTIC Science & Technology

    2015-10-01

    the Task Force spent nearly $43 million to construct a compressed natural gas (CNG) automobile filling station in the city of Sheberghan...construction and operation of a CNG automobile filling station in the city of Sheberghan, near Afghanistan’s natural gas fields.4 Figure 1 – The pumps...Mazar-e Sharif, the second-largest city in Afghanistan (sic), with a market of 100,000 cars;5  Provide subject matter expert support to the CNG

  1. Accelerating solitons in gas-filled hollow-core photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Facão, M.; Carvalho, M. I.; Almeida, P.

    2013-06-01

    We found the self-similar solitary solutions of a recently proposed model for the propagation of pulses in gas-filled hollow-core photonic crystal fibers that includes a plasma induced nonlinearity. As anticipated for a simpler model and using a perturbation analysis, there are indeed stationary solitary waves that accelerate and self-shift to higher frequencies. However, if the plasma nonlinearity strength is large or the pulse amplitudes are small, the solutions have distinguished long tails and decay as they propagate.

  2. Development of a Gas Filled Magnet spectrometer within the FIPPS project

    NASA Astrophysics Data System (ADS)

    Chebboubi, A.; Kessedjian, G.; Faust, H.; Blanc, A.; Jentschel, M.; Köster, U.; Materna, T.; Méplan, O.; Sage, C.; Serot, O.

    2016-06-01

    The Fission Product Prompt γ -ray Spectrometer, FIPPS, is under development to enable prompt γ -ray spectroscopy correlated with fission fragment identification. This will open new possibilities in the study of fission and of nuclear structure of neutron rich nuclei. FIPPS will consist of an array of γ and neutron detectors coupled with a fission fragment filter. The chosen solution for the filter is a Gas Filled Magnet (GFM). Both experimental and modeling work was performed in order to extract the key parameters of such a device and design the future GFM of the FIPPS project. Experiments performed with a GFM behind the LOHENGRIN spectrometer demonstrated the capability of additional beam purification.

  3. Shock-induced PT-symmetric potentials in gas-filled photonic-crystal fibers

    NASA Astrophysics Data System (ADS)

    Saleh, Mohammed F.; Marini, Andrea; Biancalana, Fabio

    2014-02-01

    We have investigated the interaction between a strong soliton and a weak probe with certain configurations that allow optical trapping in gas-filled hollow-core photonic-crystal fibers in the presence of the shock effect. We have shown theoretically and numerically that the shock term can lead to an unbroken parity-time- (PT-) symmetric potential in these kinds of fibers. Time irreversible behavior, a signature feature of the PT symmetry, is also demonstrated numerically. Our results will open different configurations and avenues for observing PT-symmetry breaking in optical fibers, without the need to resort to complex optical systems.

  4. Automation of experiments at the Dubna gas-filled separator of recoil nuclei: Part II

    NASA Astrophysics Data System (ADS)

    Tsyganov, Yu. S.

    2015-03-01

    An application developed in Builder C++ (Windows) for the offline analysis of experimental data from the spectrometer of the gas-filled separator of recoil nuclei (Flerov Laboratory of Nuclear Reactions) based on the double-sided silicon strip detector is discussed. The automatic express method developed for calibrating 48 strips of the silicon position-sensitive detector based on the three most energetic spectral lines from the natYb + 48Ca▭*Th reaction is compared to the results produced by more rigorous calibration methods. The examples of spectra for this reaction and the results of filtering for the proposed calibration algorithm are given.

  5. New Hadron Monitor By Using A Gas-Filled RF Resonator

    SciTech Connect

    Yonehara, Katsuya; Fasce, Giorgio; Flanagan, Gene; Johnson, Rolland; Tollestrup, Alvin; Zwaska, Robert

    2015-05-01

    It is trend to build an intense neutrino beam facility for the fundamental physics research, e.g. LBNF at Fermilab, T2K at KEK, and CNGS at CERN. They have investigated a hadron monitor to diagnose the primary/secondary beam quality. The existing hadron monitor based on an ionization chamber is not robust in the high-radiation environment vicinity of MW-class secondary particle production targets. We propose a gas-filled RF resonator to use as the hadron monitor since it is simple and hence radiation robust in this environment. When charged particles pass through the resonator they produce ionized plasma via the Coulomb interaction with the inert gas. The beam-induced plasma changes the permittivity of inert gas. As a result, a resonant frequency in the resonator shifts with the amount of ionized electrons. The radiation sensitivity is adjustable by the inert gas pressure and the RF amplitude. The hadron profile will be reconstructed with a tomography technique in the hodoscope which consists of X, Y, and theta layers by using a strip-shaped gas resonator. The sensitivity and possible system design will be shown in this presentation.

  6. Influence of Intense Beam in High Pressure Hydrogen Gas Filled RF Cavities

    SciTech Connect

    Yonehara, K.; Chung, M.; Collura, M.G.; Jana, M.R.; Leonova, M.; Moretti, A.; Popovic, M.; Schwarz, T.; Tollestrup, A.; Johnson, R.P.; Franagan, G.; /Muons, Inc. /IIT

    2012-05-01

    The influence of an intense beam in a high-pressure gas filled RF cavity has been measured by using a 400 MeV proton beam in the Mucool Test Area at Fermilab. The ionization process generates dense plasma in the cavity and the resultant power loss to the plasma is determined by measuring the cavity voltage on a sampling oscilloscope. The energy loss has been observed with various peak RF field gradients (E), gas pressures (p), and beam intensities in nitrogen and hydrogen gases. Observed RF energy dissipation in single electron (dw) in N{sub 2} and H{sub 2} gases was 2 10{sup -17} and 3 10{sup -17} Joules/RF cycle at E/p = 8 V/cm/Torr, respectively. More detailed dw measurement have been done in H{sub 2} gas at three different gas pressures. There is a clear discrepancy between the observed dw and analytical one. The discrepancy may be due to the gas density effect that has already been observed in various experiments.

  7. Gas Filled RF Resonator Hadron Beam Monitor for Intense Neutrino Beam Experiments

    SciTech Connect

    Yonehara, Katsuya; Abrams, Robert; Dinkel, Holly; Freemire, Ben; Johnson, Rolland; Kazakevich, Grigory; Tollestrup, Alvin; Zwaska, Robert

    2016-06-01

    MW-class beam facilities are being considered all over the world to produce an intense neutrino beam for fundamental particle physics experiments. A radiation-robust beam monitor system is required to diagnose the primary and secondary beam qualities in high-radiation environments. We have proposed a novel gas-filled RF-resonator hadron beam monitor in which charged particles passing through the resonator produce ionized plasma that changes the permittivity of the gas. The sensitivity of the monitor has been evaluated in numerical simulation. A signal manipulation algorithm has been designed. A prototype system will be constructed and tested by using a proton beam at the MuCool Test Area at Fermilab.

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

    NASA Technical Reports Server (NTRS)

    Sakurai, H.; Ramsey, B. D.

    1991-01-01

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

  9. Factors that affect the efficiency of antisense oligodeoxyribonucleotide transfection by insonated gas-filled lipid microbubbles

    NASA Astrophysics Data System (ADS)

    Zhao, Ying-Zheng; Lu, Cui-Tao

    2008-03-01

    Objective: To investigate the factors that affect the efficiency of antisense oligodeoxyribonucleotide(AS-ODNs) transfection by insonated gas-filled lipid microbubbles. Methods: Lipid microbubbles filled with two types of gases-air and C3F8, were prepared respectively. An AS-ODNs sequence HA824 and a breast cancer cell line SK-BR-3 were used to define the various operating variables determining the transfection efficiency of insonated microbubbles. Two mixing methods, three levels of mixing speed, different mixing durations and various ultrasound initiation time after mixing were examined respectively. Transfection efficiency was detected by fluorescence microscopy. Results: C3F8 microbubbles gave higher levels of AS-ODNs transfection efficiency than air microbubbles in all test conditions. Transfection efficiency resulted from mixing method A (incubation of HA824 and microbubbles before mixing cells) did not show significant difference with that of mixing method B (without incubation of HA824 and microbubbles before mixing cells). Mixing speed, duration of mixing and ultrasound initiation time after mixing were central to determining HA824 transfection efficiency in vitro. The optimum parameters for SK-BR-3 cells were found at a mixing speed of 40-50 rpm for 30-60 s with less than 60 s delay before ultrasound. Conclusion: Ultrasound-mediated AS-ODNs transfection enhanced by C3F8-filled lipid microbubbles represents an effective avenue for AS-ODNs transfer.

  10. Development of a low-level 39Ar calibration standard – Analysis by absolute gas counting measurements augmented with simulation

    DOE PAGES

    Williams, Richard M.; Aalseth, C. E.; Brandenberger, J. M.; ...

    2017-02-17

    Here, this paper describes the generation of 39Ar, via reactor irradiation of potassium carbonate, followed by quantitative analysis (length-compensated proportional counting) to yield two calibration standards that are respectively 50 and 3 times atmospheric background levels. Measurements were performed in Pacific Northwest National Laboratory's shallow underground counting laboratory studying the effect of gas density on beta-transport; these results are compared with simulation. The total expanded uncertainty of the specific activity for the ~50 × 39Ar in P10 standard is 3.6% (k=2).

  11. High temperature corrosion of hot-dip aluminized steel in Ar/1%SO2 gas

    NASA Astrophysics Data System (ADS)

    Abro, Muhammad Ali; Lee, Dong Bok

    2017-01-01

    Carbon steels were hot-dip aluminized in Al or Al-1at%Si baths, and corroded in Ar/1%SO2 gas at 700-800 °C for up to 50 h. The aluminized layers consisted of not only an outer Al(Fe) topcoat that had interdispersed needle-like Al3Fe particles but also an inner Al-Fe alloy layer that consisted of an outer Al3Fe layer and an inner Al5Fe2 layer. The Si addition in the bath made the Al(Fe) topcoat thin and nonuniform, smoothened the tongue-like interface between the Al-Fe alloy layer and the substrate, and increased the microhardness of the aluminized layer. The aluminized steels exhibited good corrosion resistance by forming thin α-Al2O3 scales, along with a minor amount of iron oxides on the surface. The interdiffusion that occurred during heating made the aluminized layer thick and diffuse, resulting in the formation of Al5Fe2, AlFe and AlFe3 layers. It also smoothened the tongue-like interface, and decreased the microhardness of the aluminized layer. The non-aluminized steel formed thick, nonadherent, nonprotective (Fe3O4, FeS)-mixed scales.

  12. Measurement of 34Ar(α , p) 37 K using the JENSA Gas Jet Target

    NASA Astrophysics Data System (ADS)

    Browne, Justin; Chipps, Kelly; Schatz, Hendrik; Schmidt, Konrad; Jensa Collaboration Collaboration

    2016-09-01

    X-ray bursts are very luminous thermonuclear explosions that occur in binary star systems. In these systems, a neutron star accreting matter from a companion star undergoes increased thermonuclear burning, which causes a breakout from the hot CNO cycle into the αp-process. The rates of (α,p) reactions can significantly impact the lightcurve and elemental abundances resulting from the X-ray burst. Using a radioactive ion beam at the National Superconducting Cyclotron Laboratory (NSCL), the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target is used to directly measure (α,p) reactions. The 34Ar(α,p)37K reaction rate was measured by detecting reaction products in the SuperORRUBA silicon detector array and a position-sensitive ionization chamber, while γ-rays were detected in the HAGRiD LaBr3 detector array. Preliminary results from this experiment will be presented. This research is supported by the U. S. Department of Energy and the National Science Foundation.

  13. Mapping the Ionization State of Laser-Irradiated Ar Gas Jets With Multi-Wavelength Monochromatic X-Ray Imaging

    SciTech Connect

    Kugland, N L; Doppner, T; Kemp, A; Schaeffer, D; Glenzer, S H; Niemann, C

    2010-04-08

    Two-dimensional monochromatic images of fast-electron stimulated Ar K{alpha} and He-{alpha} x-ray self-emission have recorded a time-integrated map of the extent of Ar{sup {approx}6+} and Ar{sup 16+} ions, respectively, within a high density (10{sup 20} cm{sup -3} atomic density) Ar plasma. This plasma was produced by irradiating a 2 mm wide clustering Ar gas jet with an ultra-high intensity (10{sup 19} W/cm{sup 2}, 200 fs) Ti:Sapphire laser operating at 800 nm. Spherically bent quartz crystals in the 200 (for K{alpha}) and 201 (for He-{alpha}) planes were used as near-normal incidence reflective x-ray optics. We see that a large (830 {micro}m long) region of plasma emits K{alpha} primarily along the laser axis, while the He-{alpha} emission is confined to smaller hot spot (230 {micro}m long) region that likely corresponds to the focal volume of the f/8 laser beam. X-ray spectra from a Bragg spectrometer operating in the von Hamos geometry, which images in one dimension, indicate that the centroids of the K{alpha} and He-{alpha} emission regions are separated by approximately 330 {micro}m along the laser axis.

  14. Collision-induced hyper-Rayleigh spectrum of H(2)-Ar gas mixture.

    PubMed

    Bancewicz, Tadeusz; Głaz, Waldemar; Godet, Jean-Luc; Maroulis, George

    2008-09-28

    The collision-induced hyper-Rayleigh (CIHR) spectra of the gaseous H(2)-Ar mixture are discussed in the binary regime on the basis of our ab initio computed H(2)-Ar collision-induced (CI) first dipole hyperpolarizability tensor Deltabeta(R). A method for the computation of the spherical, rotationally adapted components Deltabeta(lambdaL) ((s,K))(R) of Deltabeta(R) needed for spectroscopic line shape analysis is proposed. Both the vector and the septor parts of the H(2)-Ar CIHR spectrum are evaluated at room (T=295 K) temperature. The spectra are calculated assuming the full quantum computations based on the Schrodinger equation of the relative translational motion of H(2)-Ar as well as semiclassical methods (classical trajectory approach and Birnbaum-Cohen model translational profiles). The H(2)-Ar pair CIHR septor spectrum has been found stronger than the vector one.

  15. High pressure gas filled RF cavity beam test at the Fermilab Mucool test area

    NASA Astrophysics Data System (ADS)

    Freemire, Ben

    With a new generation of lepton colliders being conceived, muons have been proposed as an alternative particle to electrons. Muons lose less energy to synchrotron radiation and a Muon Collider can provide luminosity within a smaller energy range than a comparable electron collider. This allows a circular collider to be built. As part of the accelerator, it would also be possible to allow the muons to decay to study neutrinos. Because the muon is an unstable particle, a muon beam must be cooled and accelerated within a short amount of time. Muons are generated with a huge phase space, so radio frequency cavities placed in strong magnetic fields are required to bunch, focus, and accelerate the muons. Unfortunately, traditional vacuum RF cavities have been shown to break down in the magnetic fields necessary. To successfully operate RF cavities in strong magnetic fields, the cavity can be filled with a high pressure gas in order to mitigate breakdown. The gas has the added benefit of providing cooling for the beam. The electron-ion plasma created in the cavity by the beam absorbs energy and degrades the accelerating electric field of the cavity. As electrons account for the majority of the energy loss in the cavity, their removal in a short time is highly desirable. The addition of an electronegative dopant gas can greatly decrease the lifetime of an electron in the cavity. Measurements in pure hydrogen of the energy consumption of electrons in the cavity range in 10-18 and 10-16 joules per RF cycle per electron. When hydrogen doped with dry air is used, measurements of the power consumption indicate an energy loss range of 10-20 to 10-18 joules per RF cycle per ion, two orders of magnitude improvement over non-doped measurements. The lifetime of electrons in a mixture of hydrogen gas and dry air has been measured from < 1 ns, up to 200 ns. The results extrapolated to the parameters of a Neutrino Factory and Muon Collider indicate that a high pressure gas filled RF

  16. Use of the gas-filled-magnet technique for particle identification at low energies

    SciTech Connect

    Rehm, K.K.; Jiang, C.L.; Paul, M.

    1995-08-01

    Reaction studies of interest to astrophysics with radioactive ion beams will be done mainly in inverse reaction kinematics, i.e., heavy particles bombarding a hydrogen target. The low energy of the outgoing heavy reaction products makes particle identification with respect to mass and nuclear charge a major challenge. For the planned {sup 18}F(p,{alpha}) experiment one expects five different types of particles in the outgoing channels: {sup 18}F and {sup 18}O (from elastic scattering of {sup 18}F and {sup 18}O on {sup 12}C), {sup 15}O and {sup 15}N (from the {sup 18}F and {sup 18}O induced (p,{alpha}) reactions) and {sup 12}C recoils from the polypropylene target. While mass determination can be achieved easily by time-of-flight (TOF) measurements, a determination of the nuclear charge presents a challenge, especially if the energy of the particles is below 500 keV/u. We studied the gas-filled magnet technique for Z-identification of light ions between Z = 6-9. In a gas-filled magnet the particles move with an average charge state {bar q} which in one parameterization is given by {bar q} = Z ln(avZ{sup {alpha}})/ln(bZ{sup {beta}}) where Z is the nuclear charge of the ions and v their velocity. Introducing into the expression for the magnetic rigidity B{rho} = mv/{bar q} results in a Z dependence of B{rho} which is valid to very low velocities. As a magnet we used the Enge split-pole spectrograph which was filled with nitrogen gas at a pressure of 0.5 Torr. The particles were detected in the focal plane with a 50 x 10 cm{sup 2} parallel-grid-avalanche counter which measured TOF and magnetic rigidity. The mass and Z separation was tested with {sup 13}C and {sup 18}O beams at energies of about 600 keV/u and recoil particles ranging from {sup 12}C to {sup 19}F. The Z-separation obtained at these energies was {triangle}Z/Z = 0.28 which is sufficient to separate individual elements for Z < 10.

  17. Spectral and polarimetric characterization of the Gas Pixel Detector filled with dimethyl ether

    NASA Astrophysics Data System (ADS)

    Muleri, F.; Soffitta, P.; Baldini, L.; Bellazzini, R.; Brez, A.; Costa, E.; Fabiani, S.; Krummenacher, F.; Latronico, L.; Lazzarotto, F.; Minuti, M.; Pinchera, M.; Rubini, A.; Sgró, C.; Spandre, G.

    2010-08-01

    The Gas Pixel Detector belongs to the very limited class of gas detectors optimized for the measurement of X-ray polarization in the emission of astrophysical sources. The choice of the mixture in which X-ray photons are absorbed and photoelectrons propagate, deeply affects both the energy range of the instrument and its performance in terms of gain, track dimension and ultimately, polarimetric sensitivity. Here we present the characterization of the Gas Pixel Detector with a 1 cm thick cell filled with dimethyl ether (DME) at 0.79 atm, selected among other mixtures for the very low diffusion coefficient. Almost completely polarized and monochromatic photons were produced at the calibration facility built at INAF/IASF-Rome exploiting Bragg diffraction at nearly 45°. For the first time ever, we measured the modulation factor and the spectral capabilities of the instrument at energies as low as 2.0 keV, but also at 2.6, 3.7, 4.0, 5.2 and 7.8 keV. These measurements cover almost completely the energy range of the instrument and allows to compare the sensitivity achieved with that of the standard mixture, composed of helium and DME.

  18. Comparison of surface vacuum ultraviolet emissions with resonance level number densities. II. Rare-gas plasmas and Ar-molecular gas mixtures

    SciTech Connect

    Boffard, John B. Lin, Chun C.; Wang, Shicong; Wendt, Amy E.; Culver, Cody; Radovanov, Svetlana; Persing, Harold

    2015-03-15

    Vacuum ultraviolet (VUV) emissions from excited plasma species can play a variety of roles in processing plasmas, including damaging the surface properties of materials used in semiconductor processing. Depending on their wavelength, VUV photons can easily transmit thin upper dielectric layers and affect the electrical characteristics of the devices. Despite their importance, measuring VUV fluxes is complicated by the fact that few materials transmit at VUV wavelengths, and both detectors and windows are easily damaged by plasma exposure. The authors have previously reported on measuring VUV fluxes in pure argon plasmas by monitoring the concentrations of Ar(3p{sup 5}4s) resonance atoms that produce the VUV emissions using noninvasive optical emission spectroscopy in the visible/near-infrared wavelength range [Boffard et al., J. Vac. Sci. Technol., A 32, 021304 (2014)]. Here, the authors extend this technique to other rare-gases (Ne, Kr, and Xe) and argon-molecular gas plasmas (Ar/H{sub 2}, Ar/O{sub 2}, and Ar/N{sub 2}). Results of a model for VUV emissions that couples radiation trapping and the measured rare-gas resonance level densities are compared to measurements made with both a calibrated VUV photodiode and a sodium salicylate fluorescence detection scheme. In these more complicated gas mixtures, VUV emissions from a variety of sources beyond the principal resonance levels of the rare gases are found to contribute to the total VUV flux.

  19. GAS AND DUST ABSORPTION IN THE DoAr 24E SYSTEM

    SciTech Connect

    Kruger, Andrew J.; Richter, Matthew J.; Seifahrt, Andreas; Carr, John S.; Najita, Joan R.; Moerchen, Margaret M.; Doppmann, Greg W.

    2012-11-20

    We present findings for DoAr 24E, a binary system that includes a classical infrared companion. We observed the DoAr 24E system with the Spitzer Infrared Spectrograph (IRS), with high-resolution, near-infrared spectroscopy of CO vibrational transitions, and with mid-infrared imaging. The source of high extinction toward infrared companions has been an item of continuing interest. Here we investigate the disk structure of DoAr 24E using the column densities, temperature, and velocity profiles of two CO absorption features seen toward DoAr 24Eb. We model the spectral energy distributions found using T-ReCS imaging and investigate the likely sources of extinction toward DoAr 24Eb. We find the lack of silicate absorption and small CO column density toward DoAr 24Eb suggest that the mid-infrared continuum is not as extinguished as the near-infrared, possibly due to the mid-infrared originating from an extended region. This, along with the velocity profile of the CO absorption, suggests that the source of high extinction is likely due to a disk or disk wind associated with DoAr 24Eb.

  20. Mutual Neutralization of Atomic Rare-Gas Cations (Ne+, Ar+, Kr+, Xe+) with Atomic Halide Anions (Cl-, Br-, I-)

    DTIC Science & Technology

    2015-01-07

    Belvoir, VA 22060-6218 1 cy AFRL /RVIL Kirtland AFB, NM 87117-5776 2 cys Official Record Copy AFRL /RVBXT/Dr. Albert Viggiano 1 cy... AFRL -RV-PS- TP-2015-0001 AFRL -RV-PS- TP-2015-0001 MUTUAL NEUTRALIZATION OF ATOMIC RARE- GAS CATIONS (Ne+, Ar+, Kr+, Xe+) WITH ATOMIC HALIDE...RESEARCH LABORATORY Space Vehicles Directorate 3550 Aberdeen Ave SE AIR FORCE MATERIEL COMMAND KIRTLAND AIR FORCE BASE, NM 87117-5776 REPORT

  1. Universality of Coherent Raman Gain Suppression in Gas-Filled Broadband-Guiding Photonic Crystal Fibers

    NASA Astrophysics Data System (ADS)

    Hosseini, P.; Mridha, M. K.; Novoa, D.; Abdolvand, A.; Russell, P. St. J.

    2017-03-01

    As shown in the early 1960s, the gain in stimulated Raman scattering (SRS) is drastically suppressed when the rate of creation of phonons (via a pump-to-Stokes conversion) is exactly balanced by the rate of phonon annihilation (via a pump-to-anti-Stokes conversion). This occurs when the phonon coherence waves—synchronized vibrations of a large population of molecules—have identical propagation constants for both processes; i.e., they are phase-velocity matched. As recently demonstrated, hydrogen-filled photonic crystal fiber pumped in the vicinity of its zero-dispersion wavelength provides an ideal system for observing this effect. Here we report that Raman gain suppression is actually a universal feature of SRS in gas-filled hollow-core fibers and that it can strongly impair SRS even when the phase mismatch is high, particularly at high pump powers when it is normally assumed that nonlinear processes become more (not less) efficient. This counterintuitive result means that intermodal stimulated Raman scattering (for example, between LP01 and LP11 core modes) begins to dominate at high power levels. The results reported have important implications for fiber-based Raman shifters, amplifiers, or frequency combs, especially for operation in the ultraviolet, where the Raman gain is much higher.

  2. Studies of a gas-filled helical muon beam cooling channel

    SciTech Connect

    Yonehara, K.; Derbenev, Y.; Johnson, R.P.; Roberts, T.J.; /MUONS Inc., Batavia

    2006-06-01

    A helical cooling channel (HCC) can quickly reduce the six dimensional phase space of muon beams for muon colliders, neutrino factories, and intense muon sources. The HCC is composed of solenoidal, helical dipole, and helical quadrupole magnetic fields to provide the focusing and dispersion needed for emittance exchange as the beam follows an equilibrium helical orbit through a continuous homogeneous absorber. The beam dynamics of a gas-filled helical muon beam cooling channel is studied by using Monte Carlo simulations. The results verify the cooling theory [1] of the helical magnet. The cooling performance has been improved by correcting chromatic aberration and the non-linear effects caused by the ionization energy loss process. With these improvements, a simulated cooling channel of 160 meters length has achieved a reduction of 6-dimensional (6D) phase space by a factor of 50,000.

  3. Development of a Gas Filled Magnet spectrometer coupled with the Lohengrin spectrometer for fission study

    NASA Astrophysics Data System (ADS)

    Kessedjian, G.; Chebboubi, A.; Faust, H.; Köster, U.; Materna, T.; Sage, C.; Serot, O.

    2013-03-01

    The accurate knowledge of the fission of actinides is necessary for studies of innovative nuclear reactor concepts. The fission yields have a direct influence on the evaluation of the fuel inventory or the reactor residual power after shutdown. A collaboration between the ILL, LPSC and CEA has developed a measurement program on fission fragment distributions at ILL in order to measure the isotopic and isomeric yields. The method is illustrated using the 233U(n,f)98Y reaction. However, the extracted beam from the Lohengrin spectrometer is not isobaric ions which limits the low yield measurements. Presently, the coupling of the Lohengrin spectrometer with a Gas Filled Magnet (GFM) is studied at the ILL in order to define and validate the enhanced purification of the extracted beam. This work will present the results of the spectrometer characterisation, along with a comparison with a dedicated Monte Carlo simulation especially developed for this purpose.

  4. Polystyrene Foam EOS as a Function of Porosity and Fill Gas

    NASA Astrophysics Data System (ADS)

    Mulford, Roberta; Swift, Damian

    2009-06-01

    An accurate EOS for polystyrene foam is necessary for analysis of numerous experiments in shock compression, inertial confinement fusion, and astrophysics. Plastic to gas ratios vary between various samples of foam, according to the density and cell-size of the foam. A matrix of compositions has been investigated, allowing prediction of foam response as a function of the plastic-to-air ratio. The EOS code CHEETAH allows participation of the air in the decomposition reaction of the foam, Differences between air-filled, nitrogen-blown, and CO2-blown foams are investigated, to estimate the importance of allowing air to react with plastic products during decomposition. Results differ somewhat from the conventional EOS, which are generated from values for plastic extrapolated to low densities.

  5. Suprathermal Electrons Generated by the Two-Plasmon-Decay Instability in Gas-Filled Hohlraums

    SciTech Connect

    Regan, S P; Seka, W; Stoeckl, C; Glebov, V Y; Sangster, T C; Meyerhofer, D D; McCrory, R L; Meezan, N B; Suter, L J; Glenzer, S H; Strozzi, D J; Meeker, D; Williams, E A; Jones, O S; Callahan, D A; Rosen, M D; Landen, O L; Sorce, C; MacGowan, B J; Kruer, W L

    2008-06-03

    For the first time a burst of suprathermal electrons is observed from the exploding laser-entrance-hole window of gas-filled hohlraums driven with 13.5 kJ of 351-nm laser light. The two-plasmon-decay instability appears to produce up to 20 J of hot electrons with T{sub hot} {approx} 75 keV at early times and has a sharp laser-intensity threshold between 0.3 and 0.5 x 10{sup 15} W/cm{sup 2}. The observed threshold can be exploited to mitigate preheat by window hot electrons in ignition hohlraums for the National Ignition Facility and achieve high-density, high-pressure conditions in indirect drive implosions.

  6. Investigating the effect of adding an on-axis jet to Ar gas puff Z pinches on Z

    NASA Astrophysics Data System (ADS)

    Harvey-Thompson, A. J.; Jennings, C. A.; Jones, B.; Apruzese, J. P.; Ampleford, D. J.; Lamppa, D. C.; Coverdale, C. A.; Cuneo, M. E.; Giuliani, J. L.; Hansen, S. B.; Jones, M. C.; Moore, N. W.; Rochau, G. A.; Thornhill, J. W.

    2016-10-01

    Double-shell Ar gas puff implosions driven by 16.5 ± 0.5 MA on the Z generator at Sandia National Laboratories are very effective emitters of Ar K-shell radiation (photon energy >3 keV), producing yields of 330 ± 9% kJ [B. Jones et al., Phys. Plasmas 22, 020706 (2015)]. Previous simulations and experiments have reported dramatic increases in K-shell yields when adding an on-axis jet to double shell gas puffs for some configurations. We report on a series of experiments on Z testing Ar gas puff configurations with and without an on-axis jet guided by 3D magneto-hydrodynamic (MHD) simulations. Adding an on-axis jet was found to significantly improve the performance of some, but not all, configurations. The maximum observed K-shell yield of 375 ± 9% kJ was produced with a configuration that rapidly imploded onto an on-axis jet. A dramatic difference was observed in the plasma conditions at stagnation when a jet was used, producing a narrower stagnation column in experiments with a higher density but relatively lower electron temperature. The MHD simulations accurately reproduce the experimental measurements. The conversion efficiency for electrical energy delivered to the load to K-shell x-rays is estimated to be ˜12.5% for the best-performing configuration, similar to the best results from experiments at smaller facilities.

  7. Unprecedented Enhancement of Noble Gas-Noble Metal Bonding in NgAu3(+) (Ng = Ar, Kr, and Xe) Ion through Hydrogen Doping.

    PubMed

    Ghosh, Ayan; Ghanty, Tapan K

    2016-12-22

    Behavior of gold as hydrogen in certain gold compounds and a very recent experimental report on the noble gas-noble metal interaction in Ar complexes of mixed Au-Ag trimers have motivated us to investigate the effect of hydrogen doping on the Ng-Au (Ng = Ar, Kr, and Xe) bonding through various ab initio based techniques. The calculated results show considerable strengthening of the Ng-Au bond in terms of bond length, bond energy, stretching vibrational frequency, and force constant. Particularly, an exceptional enhancement of Ar-Au bonding strength has been observed in ArAuH2(+) species as compared to that in ArAu3(+) system, as revealed from the CCSD(T) calculated Ar-Au bond energy value of 32 and 72 kJ mol(-1) for ArAu3(+) and ArAuH2(+), respectively. In the calculated IR spectra, the Ar-Au stretching frequency is blue-shifted by 65% in going from ArAu3(+) to ArAuH2(+) species. Similar trends have been obtained in the case of all Ar, Kr, and Xe complexes with Ag and Cu trimers. Among all the NgM3-kHk(+) complexes (where k = 0-2), the strongest binding in NgMH2(+) complex is attributed to significant enhancement in the covalent characteristics of the Ng-M bond and considerable increase in charge-induced dipole interaction, as shown from the topological analysis.

  8. Nitriding molybdenum: Effects of duration and fill gas pressure when using 100-Hz pulse DC discharge technique

    NASA Astrophysics Data System (ADS)

    Ikhlaq, U.; R., Ahmad; Shafiq, M.; Saleem, S.; S. Shah, M.; Hussain, T.; A. Khan, I.; K., Abbas; S. Abbas, M.

    2014-10-01

    Molybdenum is nitrided by a 100-Hz pulsed DC glow discharge technique for various time durations and fill gas pressures to study the effects on the surface properties of molybdenum. X-ray diffractometry (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) are used for the structural and morphological analysis of the nitrided layers. Vickers' microhardness tester is utilized to investigate surface microhardness. Phase analysis shows the formation of more molybdenum nitride molecules for longer nitriding durations at fill gas pressures of 2 mbar and 3 mbar (1 bar = 105 Pa). A considerable increase in surface microhardness (approximately by a factor of 2) is observed for longer duration (10 h) and 2-mbar pressure. Longer duration (10 h) and 2-mbar fill gas pressure favors the formation of homogeneous, smooth, hard layers by the incorporation of more nitrogen.

  9. Comparison of the performance of forward fill/flush and reverse fill/flush flow modulation in comprehensive two-dimensional gas chromatography.

    PubMed

    Krupčík, Jan; Gorovenko, Roman; Špánik, Ivan; Sandra, Pat; Giardina, Matthew

    2016-09-30

    The performances of forward flow fill and flush (FFF) and of reverse flow fill and flush (RFF) in flow modulated comprehensive two-dimensional gas chromatography (GC×GC) using the same volume of the sampling channel have been studied and compared. Sample models include a reference mixture of hydrocarbons at low concentration, a petroleum reformate product and the essential oil of Rosa damascena Miller. The latter samples contain solutes in different concentrations but some up to 30% allowing to study overloading phenomena in detail. For solutes injected at low quantity, the performance of FFF and RFF is similar. For solutes present in a sample at high quantity, RFF guarantees less broadening and spreading resulting in better quantitation.

  10. Numerical study of an ArH2 gas mixture flowing inside and outside a dc plasma torch

    NASA Astrophysics Data System (ADS)

    Eichert, P.; Imbert, M.; Coddet, C.

    1998-12-01

    The flow of gas mixtures in a dc plasma torch is studied using the CFD PHOENICS (CFD PHOENICS, Berkeley, CA) code. In the model, the cold gas mixture (300 K), initially constituted of 85 vol% Ar and 15 vol% H, is introduced into a power input zone where it takes energy and is ejected in the surrounding atmosphere at constant pressure (105 Pa). The flow is assumed to be in chemical equilibrium. Equations of mass, momentum, and energy are discretized using a control-volume method. The turbulent flow is modeled by a k-ɛ two-equations model for the turbulent kinetic energy and its dissipation rate. Finally, the algebraic coupling equations set is solved by means of the SIMPLEST algorithm, implemented into the CFD code, using a hybrid interpolation scheme. Results concern the effect of the torch power on the ArH2 flow. The phenomenon is analyzed through the evolution of velocity and temperature inside and outside the torch. From these calculations, the effect of ambient gas entrainment by the jet is emphasized and a comparison of the level of entrained gas is made with experimental data.

  11. Volatile out gassing characteristics of highly filled ethylene vinyl acetate binder materials: Gas phase infra-red spectroscopy

    SciTech Connect

    Patel, Mogon; Bowditch, Martin; Jones, Ben; Netherton, David; Khan, Niaz; Letant, Sonia; Maxwell, Robert S.; Birdsell, Stephen A.

    2012-12-08

    Gas phase Infra-red (IR) spectroscopy has been used to investigate volatile out gassing properties of highly filled poly (ethylene-co-vinyl acetate) materials. In these studies, a Scout-ENTM heated gas cell was interfaced to a vacuum FTIR spectrometer, and the quantification of evolved species was achieved through calibration of the gas cell with certified gas standards. The volatile out gassing properties were monitored as a function of time during storage at 75°C under vacuum conditions (< 1mbar). Acetic acid, carbon dioxide and water were identified as the major out gassing products through IR absorption peaks at 1797, 2354 and 3853 cm-1, respectively. We present a comparison of three highly filled poly (ethyleneco- vinyl acetate) resins.

  12. Volatile out gassing characteristics of highly filled ethylene vinyl acetate binder materials: Gas phase infra-red spectroscopy

    DOE PAGES

    Patel, Mogon; Bowditch, Martin; Jones, Ben; ...

    2012-12-08

    Gas phase Infra-red (IR) spectroscopy has been used to investigate volatile out gassing properties of highly filled poly (ethylene-co-vinyl acetate) materials. In these studies, a Scout-ENTM heated gas cell was interfaced to a vacuum FTIR spectrometer, and the quantification of evolved species was achieved through calibration of the gas cell with certified gas standards. The volatile out gassing properties were monitored as a function of time during storage at 75°C under vacuum conditions (< 1mbar). Acetic acid, carbon dioxide and water were identified as the major out gassing products through IR absorption peaks at 1797, 2354 and 3853 cm-1, respectively.more » We present a comparison of three highly filled poly (ethyleneco- vinyl acetate) resins.« less

  13. Simulation for Large-Area, Inductively-Coupled Plasma Systems Using an Ar/Cl2 Gas Mixture.

    PubMed

    Oh, Seon-Geun; Lee, Young-Jun; Jeon, Jae-Hong; Kim, Young-Jin; Seo, Jong-Hyun; Choe, Hee-Hwan

    2015-11-01

    As research and development of high-performance devices are becoming increasingly important in the flat panel display industry, new structures and processes are essential to improve the performance of the TFT backplane. Also, high-density plasma systems are needed for new device fabrications. Chlorine-based, inductively-coupled plasma systems are widely used for highly-selective, anisotropic etching of polysilicon layers. In this paper, a plasma simulation for a large-area ICP system (8th glass size and 9 planar antenna set) was conducted using Ar/Cl2 gas. Transport models and Maxwell Equations were applied to calculate the plasma parameters such as electron density, electron temperature and electric potential. In addition, the spatial distribution of ions such as Ar+, Cl2+, Cl-, Cl+ were investigated respectively.

  14. Development of high pressure-high vacuum-high conductance piston valve for gas-filled radiation detectors

    NASA Astrophysics Data System (ADS)

    Prasad, D. N.; Ayyappan, R.; Kamble, L. P.; Singh, J. P.; Muralikrishna, L. V.; Alex, M.; Balagi, V.; Mukhopadhyay, P. K.

    2008-05-01

    Gas-filled radiation detectors need gas filling at pressures that range from few cms of mercury to as high as 25kg/cm2 at room temperature. Before gas-filling these detectors require evacuation to a vacuum of the order of ~1 × 10-5 mbar. For these operations of evacuation and gas filling a system consisting of a vacuum pump with a high vacuum gauge, gas cylinder with a pressure gauge and a valve is used. The valve has to meet the three requirements of compatibility with high-pressure and high vacuum and high conductance. A piston valve suitable for the evacuation and gas filling of radiation detectors has been designed and fabricated to meet the above requirements. The stainless steel body (80mm×160mm overall dimensions) valve with a piston arrangement has a 1/2 inch inlet/outlet opening, neoprene/viton O-ring at piston face & diameter for sealing and a knob for opening and closing the valve. The piston movement mechanism is designed to have minimum wear of sealing O-rings. The valve has been hydrostatic pressure tested up to 75bars and has Helium leak rate of less than 9.6×10-9 m bar ltr/sec in vacuum mode and 2×10-7 mbar ltr/sec in pressure mode. As compared to a commercial diaphragm valve, which needed 3 hours to evacuate a 7 litre chamber to 2.5×10-5 mbar, the new valve achieved vacuum 7.4×10-6mbar in the same time under the same conditions.

  15. Highly selective and precisely controlled aluminum etching by Ar/HBr/CH3F/O2 gas chemistry

    NASA Astrophysics Data System (ADS)

    Suzuki, Eiji; Ohtake, Hiroto; Ohsawa, Yusuke; Kumar, Kaushik; Sasaki, Masaru

    2014-01-01

    Highly selective and precisely controlled aluminum etching was investigated by using plasma with a new Ar/HBr/CH3F/O2 gas chemistry. Generally, an aluminum surface is oxidized, leading to difficulties in the precise control of nm/min-level aluminum etching with a high selectivity to SiO2 of more than 10. The new gas chemistry enabled precise aluminum etching with a high selectivity to oxide of 10 and a low etching rate of 10 nm/min. In this gas chemistry, the aluminum surface remained oxidized by oxygen during etching and the oxidized surface was reduced by CH3F. The oxidized aluminum surface was etched by radicals from CH3F and the etching rate was decreased by HBr.

  16. Coordination of ScO+ and YO+ by multiple Ar, Kr, and Xe atoms in noble gas matrixes: a matrix isolation infrared spectroscopic and theoretical study.

    PubMed

    Zhao, Yanying; Gong, Yu; Chen, Mohua; Ding, Chuanfan; Zhou, Mingfei

    2005-12-29

    The combination of matrix isolation infrared spectroscopic and quantum chemical calculation results provide strong evidence that scandium and yttrium monoxide cations, ScO+ and YO+, coordinate multiple noble gas atoms in forming noble gas complexes. The results showed that ScO+ coordinates five Ar, Kr, or Xe atoms, and YO+ coordinates six Ar or Kr and five Xe atoms in solid noble gas matrixes. Hence, the ScO+ and YO+ cations trapped in solid noble gas matrixes should be regarded as the [ScO(Ng)5]+ (Ng = Ar, Kr, or Xe), [YO(Ng)6]+ (Ng = Ar or Kr) or [YO(Xe)5]+ complexes. Experiments with dilute krypton or xenon in argon or krypton in xenon produced new IR bands, which are due to the stepwise formation of the [ScO(Ar)(5-n)(Kr)n]+, [ScO(Kr)(5-n)(Xe)n]+ (n = 1-5), [YO(Ar)(6-n)(Kr)n]+ (n = 1-6), and [YO(Ar)(6-n)(Xe)n]+ (n = 1-4) complexes.

  17. Mutual neutralization of atomic rare-gas cations (Ne+, Ar+, Kr+, Xe+) with atomic halide anions (Cl-, Br-, I-)

    NASA Astrophysics Data System (ADS)

    Shuman, Nicholas S.; Miller, Thomas M.; Johnsen, Rainer; Viggiano, Albert A.

    2014-01-01

    We report thermal rate coefficients for 12 reactions of rare gas cations (Ne+, Ar+, Kr+, Xe+) with halide anions (Cl-, Br-, I-), comprising both mutual neutralization (MN) and transfer ionization. No rate coefficients have been previously reported for these reactions; however, the development of the Variable Electron and Neutral Density Attachment Mass Spectrometry technique makes it possible to measure the difference of the rate coefficients for pairs of parallel reactions in a Flowing Afterglow-Langmuir Probe apparatus. Measurements of 18 such combinations of competing reaction pairs yield an over-determined data set from which a consistent set of rate coefficients of the 12 MN reactions can be deduced. Unlike rate coefficients of MN reactions involving at least one polyatomic ion, which vary by at most a factor of ˜3, those of the atom-atom reactions vary by at least a factor 60 depending on the species. It is found that the rate coefficients involving light rare-gas ions are larger than those for the heavier rare-gas ions, but the opposite trend is observed in the progression from Cl- to I-. The largest rate coefficient is 6.5 × 10-8 cm3 s-1 for Ne+ with I-. Rate coefficients for Ar+, Kr+, and Xe+ reacting with Br2- are also reported.

  18. Mutual neutralization of atomic rare-gas cations (Ne(+), Ar(+), Kr(+), Xe(+)) with atomic halide anions (Cl(-), Br(-), I(-)).

    PubMed

    Shuman, Nicholas S; Miller, Thomas M; Johnsen, Rainer; Viggiano, Albert A

    2014-01-28

    We report thermal rate coefficients for 12 reactions of rare gas cations (Ne(+), Ar(+), Kr(+), Xe(+)) with halide anions (Cl(-), Br(-), I(-)), comprising both mutual neutralization (MN) and transfer ionization. No rate coefficients have been previously reported for these reactions; however, the development of the Variable Electron and Neutral Density Attachment Mass Spectrometry technique makes it possible to measure the difference of the rate coefficients for pairs of parallel reactions in a Flowing Afterglow-Langmuir Probe apparatus. Measurements of 18 such combinations of competing reaction pairs yield an over-determined data set from which a consistent set of rate coefficients of the 12 MN reactions can be deduced. Unlike rate coefficients of MN reactions involving at least one polyatomic ion, which vary by at most a factor of ∼3, those of the atom-atom reactions vary by at least a factor 60 depending on the species. It is found that the rate coefficients involving light rare-gas ions are larger than those for the heavier rare-gas ions, but the opposite trend is observed in the progression from Cl(-) to I(-). The largest rate coefficient is 6.5 × 10(-8) cm(3) s(-1) for Ne(+) with I(-). Rate coefficients for Ar(+), Kr(+), and Xe(+) reacting with Br2 (-) are also reported.

  19. Simulations of the 3-Shock HDC gas-filled hohlraum experiments at the NIF

    NASA Astrophysics Data System (ADS)

    Milovich, Jose; Ross, J. S.; Ho, D.; Weber, C.; Sepke, S.; Khan, S.; Cerjan, C.; Meezan, N.; MacKinnon, A.

    2015-11-01

    We describe simulation efforts to design and field a series of high-density-carbon (HDC) capsule tuning experiments in 1.6 mg/cc gas-filled hohlraums at the National Ignition Facility (NIF), culminating in two DT-layered shots. The radiation-hydrodynamics code HYDRA coupled to an off-line power transfer model was employed to ascertain the optimal laser pulse that minimizes radiation asymmetries and implosion adiabat for a given stability margin. We found that these HDC targets have similar sensitivity as their CH ``high-foot'' counterparts when laser cone-fraction and power as well as ablator thickness are varied, leading to comparable implosions. A point of divergence, however, is the measured neutron down-scatter-ratio (DSR) that typically gauges the degree of compression obtained in a DT implosion, with HDC targets having approximately half the CH value. Concerted efforts are underway to understand and ascertain the causes of this discrepancy. Simulations and comparisons with data will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

  20. Gas-filled microbubble-mediated delivery of antigen and the induction of immune responses.

    PubMed

    Bioley, Gilles; Lassus, Anne; Bussat, Philippe; Terrettaz, Jacques; Tranquart, François; Corthésy, Blaise

    2012-09-01

    The use of well characterized recombinant or purified protein antigens (Ag) for vaccination is of interest for safety reasons and in the case where inactivated pathogens are not available (cancer, allergy). However it requires the addition of adjuvants such as Ag carrier or immune stimulators to potentiate their immunogenicity. In this study, we demonstrated that gas-filled microbubbles (MB) can serve as an efficient Ag delivery system to promote phagocytosis of the model Ag ovalbumin (OVA) without the need of ultrasound application. Once internalized by DC, OVA was processed and presented to both CD4 and CD8 T cells in vitro; such observations were coupled with the capacity of MB to activate DC. In vivo administration of MB-associated OVA in naïve wild-type Balb/c mice resulted in the induction of OVA-specific antibody and T cell responses. Detailed characterization of the generated immune response demonstrated the production of both IgG1 and IgG2a serum antibodies, as well as the secretion of IFN-γ and IL-10 by splenocytes. Interestingly, similar results were obtained with human DC in regards of Ag delivery and cell activation. Therefore, the data presented here settle the proof of principle for the further evaluation of MB-based immunomodulation studies.

  1. Raman-free nonlinear optical effects in high pressure gas-filled hollow core PCF.

    PubMed

    Azhar, M; Wong, G K L; Chang, W; Joly, N Y; Russell, P St J

    2013-02-25

    The effective Kerr nonlinearity of hollow-core kagomé-style photonic crystal fiber (PCF) filled with argon gas increases to ~15% of that of bulk silica glass when the pressure is increased from 1 to 150 bar, while the zero dispersion wavelength shifts from 300 to 900 nm. The group velocity dispersion of the system is uniquely pressure-tunable over a wide range while avoiding Raman scattering-absent in noble gases-and having an extremely high optical damage threshold. As a result, detailed and well-controlled studies of nonlinear effects can be performed, in both normal and anomalous dispersion regimes, using only a fixed-frequency pump laser. For example, the absence of Raman scattering permits clean observation, at high powers, of the interaction between a modulational instability side-band and a soliton-created dispersive wave. Excellent agreement is obtained between numerical simulations and experimental results. The system has great potential for the realization of reconfigurable supercontinuum sources, wavelength convertors and short-pulse laser systems.

  2. Heavy ion beam propagation through a gas-filled chamber for inertial confinement fusion

    SciTech Connect

    Barboza, Nigel Oswald

    1996-10-01

    The work presented here evaluates the dynamics of a beam of heavy ions propagating through a chamber filled with gas. The motivation for this research stems from the possibility of using heavy ion beams as a driver in inertial confinement fusion reactors for the purpose of generating electricity. Such a study is important in determining the constraints on the beam which limit its focus to the small radius necessary for the ignition of thermonuclear microexplosions which are the source of fusion energy. Nuclear fusion is the process of combining light nuclei to form heavier ones. One possible fusion reaction combines two isotopes of hydrogen, deuterium and tritium, to form an alpha particle and a neutron, with an accompanying release of ~17.6 MeV of energy. Generating electricity from fusion requires that we create such reactions in an efficient and controlled fashion, and harness the resulting energy. In the inertial confinement fusion (ICF) approach to energy production, a small spherical target, a few millimeters in radius, of deuterium and tritium fuel is compressed so that the density and temperature of the fuel are high enough, ~200 g/cm3 and ~20 keV, that a substantial number of fusion reactions occur; the pellet microexplosion typically releases ~350 MJ of energy in optimized power plant scenarios.

  3. Collision of an Arched Plasma-Filled Flux Rope with a Target Cloud of Initially Neutral Gas

    NASA Astrophysics Data System (ADS)

    Wongwaitayakornkul, Pakorn; Bellan, Paul M.

    2015-11-01

    The Caltech solar loop experiment apparatus had been used to create an arched plasma-filled flux rope that expands to collide with a pre-injected initially-neutral gas. We investigated such a situation in two regimes: (i) plasma made by heavy gas impacting a much lighter neutral gas cloud and (ii) a light-gas plasma impacting much heavier neutral gas. The neutral gas became ionized immediately upon impact. In regime (i), multiple shock layers were formed in the target cloud; these magnetized collisionless shocks are relevant to solar physics as such shocks develop ahead of Coronal Mass Ejections and occur in Co-rotating Interaction Regions. In regime (ii), plasma expansion was inhibited. In both cases, fast camera images, magnetic probe measurements, and spectroscopy data will be reported. The analysis of plasma and shock expansion, as well as associated density and temperature changes, will be presented.

  4. Use of propane as a quench gas in argon-filled proportional counters and comparison with other quench gases

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    An experimental investigation of propane and six other quench gases was carried out in argon-filled proportional counters. The objective of the study was to find the best gas mixture for optimizing the gas gain and the energy resolution as well as to understand the role of the ionization potential of quench gases in determining these parameters. It was found that the best gas gains and energy resolutions are obtained with propane, ethane, and isobutane in that order. The ionization potentials of these three lie below the argon metastable potentials and have the lowest value of resonance defect compared to the other quench gases. The better results obtained with these mixtures can be explained by an increased ionization yield resulting from the Penning effect. Propylene and trans-2-butene give inferior performance compared to the above three gases. Methane and carbon dioxide, the most commonly used quench gases in the argon-filled detectors, provide the worst results.

  5. Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments

    NASA Astrophysics Data System (ADS)

    Pak, A.; Dewald, E. L.; Landen, O. L.; Milovich, J.; Strozzi, D. J.; Berzak Hopkins, L. F.; Bradley, D. K.; Divol, L.; Ho, D. D.; MacKinnon, A. J.; Meezan, N. B.; Michel, P.; Moody, J. D.; Moore, A. S.; Schneider, M. B.; Town, R. P. J.; Hsing, W. W.; Edwards, M. J.

    2015-12-01

    Temporally resolved measurements of the hohlraum radiation flux asymmetry incident onto a bismuth coated surrogate capsule have been made over the first two nanoseconds of ignition relevant laser pulses. Specifically, we study the P2 asymmetry of the incoming flux as a function of cone fraction, defined as the inner-to-total laser beam power ratio, for a variety of hohlraums with different scales and gas fills. This work was performed to understand the relevance of recent experiments, conducted in new reduced-scale neopentane gas filled hohlraums, to full scale helium filled ignition targets. Experimental measurements, matched by 3D view factor calculations, are used to infer differences in symmetry, relative beam absorption, and cross beam energy transfer (CBET), employing an analytic model. Despite differences in hohlraum dimensions and gas fill, as well as in laser beam pointing and power, we find that laser absorption, CBET, and the cone fraction, at which a symmetric flux is achieved, are similar to within 25% between experiments conducted in the reduced and full scale hohlraums. This work demonstrates a close surrogacy in the dynamics during the first shock between reduced-scale and full scale implosion experiments and is an important step in enabling the increased rate of study for physics associated with inertial confinement fusion.

  6. Laser absorption, power transfer, and radiation symmetry during the first shock of inertial confinement fusion gas-filled hohlraum experiments

    SciTech Connect

    Pak, A.; Dewald, E. L.; Landen, O. L.; Milovich, J.; Strozzi, D. J.; Berzak Hopkins, L. F.; Bradley, D. K.; Divol, L.; Ho, D. D.; MacKinnon, A. J.; Meezan, N. B.; Michel, P.; Moody, J. D.; Moore, A. S.; Schneider, M. B.; Town, R. P. J.; Hsing, W. W.; Edwards, M. J.

    2015-12-15

    Temporally resolved measurements of the hohlraum radiation flux asymmetry incident onto a bismuth coated surrogate capsule have been made over the first two nanoseconds of ignition relevant laser pulses. Specifically, we study the P2 asymmetry of the incoming flux as a function of cone fraction, defined as the inner-to-total laser beam power ratio, for a variety of hohlraums with different scales and gas fills. This work was performed to understand the relevance of recent experiments, conducted in new reduced-scale neopentane gas filled hohlraums, to full scale helium filled ignition targets. Experimental measurements, matched by 3D view factor calculations, are used to infer differences in symmetry, relative beam absorption, and cross beam energy transfer (CBET), employing an analytic model. Despite differences in hohlraum dimensions and gas fill, as well as in laser beam pointing and power, we find that laser absorption, CBET, and the cone fraction, at which a symmetric flux is achieved, are similar to within 25% between experiments conducted in the reduced and full scale hohlraums. This work demonstrates a close surrogacy in the dynamics during the first shock between reduced-scale and full scale implosion experiments and is an important step in enabling the increased rate of study for physics associated with inertial confinement fusion.

  7. 78 FR 58604 - Safety Advisory: Unauthorized Filling of Compressed Gas Cylinders

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-24

    ... cylinders containing Carbon dioxide, for restaurants and other establishments. FOR FURTHER INFORMATION... safety requirements for continued use. US DOT Cylinders filled with carbon dioxide must be...

  8. Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures

    SciTech Connect

    Bates, Robert L.; Stephan Thamban, P. L.; Goeckner, Matthew J.; Overzet, Lawrence J.

    2014-07-01

    While plasmas using mixtures of SF{sub 6}, C{sub 4}F{sub 8}, and Ar are widely used in deep silicon etching, very few studies have linked the discharge parameters to etching results. The authors form such linkages in this report. The authors measured the optical emission intensities of lines from Ar, F, S, SF{sub x}, CF{sub 2}, C{sub 2}, C{sub 3}, and CS as a function of the percentage C{sub 4}F{sub 8} in the gas flow, the total gas flow rate, and the bias power. In addition, the ion current density and electron temperature were measured using a floating Langmuir probe. For comparison, trenches were etched of various widths and the trench profiles (etch depth, undercut) were measured. The addition of C{sub 4}F{sub 8} to an SF{sub 6}/Ar plasma acts to reduce the availability of F as well as increase the deposition of passivation film. Sulfur combines with carbon in the plasma efficiently to create a large optical emission of CS and suppress optical emissions from C{sub 2} and C{sub 3}. At low fractional flows of C{sub 4}F{sub 8}, the etch process appears to be controlled by the ion flux more so than by the F density. At large C{sub 4}F{sub 8} fractional flows, the etch process appears to be controlled more by the F density than by the ion flux or deposition rate of passivation film. CF{sub 2} and C{sub 2} do not appear to cause deposition from the plasma, but CS and other carbon containing molecules as well as ions do.

  9. The Gas-Filled-Magnet at PRIME Lab: Increased Sensitivity of Cosmogenic Nuclide Measurements

    NASA Astrophysics Data System (ADS)

    Caffee, M. W.; Granger, D. E.; Woodruff, T. E.

    2015-12-01

    Abstract: Using accelerator mass spectrometry (AMS), radionuclides produced either by cosmic-ray interactions or by nucleogenic means can be measured. Typical isotopic abundance ratios range from 1 x 10-10 to 1 x 10-15. The routinely measured radionuclides are 10Be, 14C, 26Al, 36Cl, and 129I. Be-10, 26Al, and 36Cl have isobaric interferences that cannot be eliminated mass through mass analysis, but dE/dx techniques suppresses these isobars enough to allow successful measurements. There are compromises, the isobar for 26Al, 26Mg, precludes successful measurement of 26Al if AlO- is injected into the accelerator. Mg- doesn't form a stable negative ion so a 26Al measurement requires injection of 26Al-. But the Al- ion is formed inefficiently; secondary ion currents using Al- are ~ 10 times less than an AlO- secondary ion beam. Precision scales with count rate so precise measurement of the 26Al/Al for all but higher ratio samples is difficult. It has long been recognized that a gas-filled-magnet (GFM) could potentially improve the measurement of those radionuclides with intractable isobar interferences. A GFM works on the principle that each element of an isobar pair, e.g. 26Mg and 26Al, has a different average charge state as it traverses a gas (3-4 Torr of N2) contained within the vacuum jacket of a magnet. The magnet steers each species with its own momentum-to-charge ratio on its own distinct radius of curvature. The magnet can be tuned to allow the isotope of interest into a dE/dx detector; most of the isobar doesn't make it into the detector. Using the PRIME Lab GFM we are now able to routinely run 26Al with a precision that is comparable to that obtained with 10Be. We are also using the GFM for routine measurements of 10Be and 36Cl. Although the improvement for these nuclides is not as pronounced as it is for 26Al, the GFM has improved the detection sensitivity for both. Our 10Be background is now ~ 5 x 10-16 and for 36Cl we can now run the source more

  10. High-power gas-discharge excimer ArF, KrCl, KrF and XeCl lasers utilising two-component gas mixtures without a buffer gas

    SciTech Connect

    Razhev, A M; Kargapol'tsev, E S; Churkin, D S

    2016-03-31

    Results of an experimental study of the influence of a gas mixture (laser active medium) composition on an output energy and total efficiency of gas-discharge excimer lasers on ArF* (193 nm), KrCl* (222 nm), KrF* (248 nm) and XeCl* (308 nm) molecules operating without a buffer gas are presented. The optimal ratios of gas components (from the viewpoint of a maximum output energy) of an active medium are found, which provide an efficient operation of laser sources. It is experimentally confirmed that for gas-discharge excimer lasers on halogenides of inert gases the presence of a buffer gas in an active medium is not a necessary condition for efficient operation. For the first time, in two-component gas mixtures of repetitively pulsed gas-discharge excimer lasers on electron transitions of excimer molecules ArF*, KrCl*, KrF* and XeCl*, the pulsed energy of laser radiation obtained under pumping by a transverse volume electric discharge in a low-pressure gas mixture without a buffer gas reached up to 170 mJ and a high pulsed output power (of up to 24 MW) was obtained at a FWHM duration of the KrF-laser pulse of 7 ns. The maximal total efficiency obtained in the experiment with two-component gas mixtures of KrF and XeCl lasers was 0.8%. (lasers)

  11. High-power gas-discharge excimer ArF, KrCl, KrF and XeCl lasers utilising two-component gas mixtures without a buffer gas

    NASA Astrophysics Data System (ADS)

    Razhev, A. M.; Kargapol'tsev, E. S.; Churkin, D. S.

    2016-03-01

    Results of an experimental study of the influence of a gas mixture (laser active medium) composition on an output energy and total efficiency of gas-discharge excimer lasers on ArF* (193 nm), KrCl* (222 nm), KrF* (248 nm) and XeCl* (308 nm) molecules operating without a buffer gas are presented. The optimal ratios of gas components (from the viewpoint of a maximum output energy) of an active medium are found, which provide an efficient operation of laser sources. It is experimentally confirmed that for gas-discharge excimer lasers on halogenides of inert gases the presence of a buffer gas in an active medium is not a necessary condition for efficient operation. For the first time, in two-component gas mixtures of repetitively pulsed gas-discharge excimer lasers on electron transitions of excimer molecules ArF*, KrCl*, KrF* and XeCl*, the pulsed energy of laser radiation obtained under pumping by a transverse volume electric discharge in a low-pressure gas mixture without a buffer gas reached up to 170 mJ and a high pulsed output power (of up to 24 MW) was obtained at a FWHM duration of the KrF-laser pulse of 7 ns. The maximal total efficiency obtained in the experiment with two-component gas mixtures of KrF and XeCl lasers was 0.8%.

  12. An experimental challenge: Unraveling the dependencies of ultrasonic and electrical properties of sandy sediments with pore-filling gas hydrates

    NASA Astrophysics Data System (ADS)

    Heeschen, Katja; Spangenberg, Erik; Seyberth, Karl; Priegnitz, Mike; Schicks, Judith M.

    2016-04-01

    The accuracy of gas hydrate quantification using seismic or electric measurements fundamentally depends on the knowledge of any factor describing the dependencies of physical properties on gas hydrate saturation. Commonly, these correlations are the result of laboratory measurements on artificially produced gas hydrates of exact saturation. Thus, the production of gas hydrates and accurate determination of gas hydrate concentrations or those of a substitute are a major concern. Here we present data of both, seismic and electric measurements on accurately quantified pore-filling ice as a substitute for natural gas hydrates. The method was validated using selected gas hydrate saturations in the same experimental set-up as well as literature data from glass bead samples [Spangenberg and Kulenkampff, 2006]. The environmental parameters were chosen to fit those of a possible gas hydrate reservoir in the Danube Delta, which is in the focus of models for joint inversions of seismic and electromagnetic data in the SUGAR III project. The small effective pressures present at this site proved to be yet another challenge for the experiments. Using a more powerful pulse generator and a 4 electrode electric measurement, respectively, models for a wide range of gas hydrate saturations between 20 - 90 % vol. could be established. Spangenberg, E. and Kulenkampff, J., Influence of methane hydrate content on electrical sediment properties. Geophysical Research Letters 2006, 33, (24).

  13. Noble Gas Analysis for Mars Robotic Missions: Evaluating K-Ar Age Dating for Mars Rock Analogs and Martian Shergottites

    NASA Technical Reports Server (NTRS)

    Park, J.; Ming, D. W.; Garrison, D. H.; Jones, J. H.; Bogard, D. D.; Nagao, K.

    2009-01-01

    The purpose of this noble gas investigation was to evaluate the possibility of measuring noble gases in martian rocks and air by future robotic missions such as the Mars Science Laboratory (MSL). The MSL mission has, as part of its payload, the Sample Analysis at Mars (SAM) instrument, which consists of a pyrolysis oven integrated with a GCMS. The MSL SAM instrument has the capability to measure noble gas compositions of martian rocks and atmosphere. Here we suggest the possibility of K-Ar age dating based on noble gas release of martian rocks by conducting laboratory simulation experiments on terrestrial basalts and martian meteorites. We provide requirements for the SAM instrument to obtain adequate noble gas abundances and compositions within the current SAM instrumental operating conditions, especially, a power limit that prevents heating the furnace above approx.1100 C. In addition, Martian meteorite analyses from NASA-JSC will be used as ground truth to evaluate the feasibility of robotic experiments to constrain the ages of martian surface rocks.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    Hyperbaric arc welding is a special application of joining the pipeline steels under seawater. In order to analyze the behavior of the arc under ambient pressure, a model is required to estimate the arc efficiency. A distributed point heat source model was employed. The simulated isotherms were calibrated iteratively to fit the actual bead cross section. Basic gas mixture rules and models were used to calculate the thermal properties of the low-temperature shielding gas under the ambient pressure of 10 bar. Nine bead-on-plate welds were deposited each of which under different Ar-He chamber gas compositions. The well-known correlation between arc efficiency (delivered heat) and the thermal conductivity was established for different gas mixtures. The arc efficiency was considered separately for the transverse and perpendicular heat sources. It was found that assigning single heat efficiency factor for the entire arc, which is usually below unity, causes a noticeable underestimation for the heat transfer in the perpendicular direction and a little overestimation in the transverse direction.

  15. Study of the 30P({alpha},p){sup 33}S reaction using a gas-filled magnetic spectrograph

    SciTech Connect

    Figueira, J. M.; Deibel, C. M.; Fernandez Niello, J. O.; Greene, J.; Jiang, C. L.; Lee, H. Y.; Pardo, R. C.; Rehm, K. E.; Ugalde, C.; Zinkann, G.; Marley, S. T.; Patel, N.; Paul, M.

    2010-08-04

    We have developed a technique using a gas-filled magnetic spectrograph which enables us to study ({alpha},p) transfer reactions of astrophysical interest in inverse kinematics and by means of the time-inverse reactions. We present preliminary experimental results of the reaction {sup 30}P({alpha},p){sup 33}S which confirm that the technique permits the study of these kinds of transfer reactions.

  16. Adding Some Gas Can Completely Change How an Object in a Liquid-Filled Housing Responds to Vibration

    NASA Astrophysics Data System (ADS)

    Torczynski, J. R.; O'Hern, T. J.; Clausen, J. R.

    2015-11-01

    Adding a little gas can completely change the motion of an object in a liquid-filled housing during vibration. A common system exhibiting this behavior is a spring-supported piston in a liquid-filled cylinder, where the gaps between them are narrow and depend on the piston position. When gas is absent, the piston's vibrational response is highly overdamped due to forcing viscous liquid through narrow gaps. When a small amount of gas is added, Bjerknes forces cause some of the gas to migrate below the piston. The resulting two gas regions form a pneumatic spring that enables the liquid to move with the piston, with the result that very little liquid is forced through the narrow gaps. This ``Couette mode'' has low damping and thus has a strong resonance near the frequency given by the pneumatic spring constant and the piston mass. At this frequency, the piston response is large, and the nonlinearity from the gap geometry produces a net force on the piston. This ``rectified'' force can be many times the piston's weight and can cause the piston to compress its supporting spring. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  17. Shadowed off-axis production of Ge nanoparticles in Ar gas atmosphere by pulsed laser deposition: Morphological, structural and charge trapping properties

    NASA Astrophysics Data System (ADS)

    Martín-Sánchez, J.; Capan, I.; Chahboun, A.; Pinto, S. R. C.; Vieira, E. M. F.; Rolo, A. G.; Gomes, M. J. M.

    2013-09-01

    In this work, a novel customized shadowed off-axis deposition set-up is used to perform an original study of Ge nanoparticles (NPs) formation in an inert Ar gas atmosphere by pulsed laser deposition at room temperature varying systematically the background Ar gas pressure (Pbase(Ar)), target-substrate distance (d) and laser repetition rate (f). The influence of these parameters on the final NPs size distributions is investigated and a fairly uniform droplets-free and non-agglomerated NPs distribution with average height = 2.8 ± 0.6 nm is obtained for optimized experimental conditions (Pbase(Ar) = 1 mbar; d = 3 cm; f = 10 Hz) with a fine control in the NPs density (from 3.2 × 109 cm-2 to 1.1 × 1011 cm-2). The crystalline quality of as-deposited NPs investigations demonstrate a strong dependence with the Ar gas pressure and a crystalline to amorphous phase volume fraction χc > 50% is found for Pbase(Ar) = 2 mbar. The NPs functionality for charge trapping applications has been successfully demonstrated by capacitance-voltage (C-V) electrical measurements.

  18. 78 FR 42817 - Safety Advisory: Unauthorized Filling of Compressed Gas Cylinders

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-17

    ... DOT 3A 1800 cylinder filled and provided by North American Coil and Beverage Group with carbon dioxide... carbon dioxide service must be successfully requalified through a visual inspection and a pressure...

  19. Characteristics and interpretation of fracture-filled gas hydrate: an example from the Ulleung Basin, East Sea of Korea

    USGS Publications Warehouse

    Lee, Myung Woong; Collett, Timothy S.

    2013-01-01

    Through the use of 2-D and 3-D seismic data, a total of thirteen sites were selected and drilled in the East Sea of Korea in 2010. A suite of logging-while-drilling (LWD) logs was acquired at each site. LWD logs from the UBGH2-3A well indicate significant gas hydrate in clay-bearing sediments including several zones with massive gas hydrate with a bulk density less than 1.0 g/m3 for depths between 5 and 103 m below the sea floor. The UBGH2-3A well was drilled on a seismically identified chimney structure with a mound feature at the sea floor. Average gas hydrate saturations estimated from the isotropic analysis of ring resistivity and P-wave velocity logs are 80 ± 13% and 47 ± 16%, respectively, whereas they are 46 ± 17% and 45 ± 16%, respectively from the anisotropic analysis. Modeling indicates that the upper part of chimney (between 5 and 45 m below sea floor [mbsf]) is characterized by gas hydrate filling near horizontal fractures (7° dip) and the lower part of chimney (between 45 and 103 mbsf) is characterized by gas hydrate filling high angle fractures on the basis of ring resistivity and P-wave velocity. The anisotropic analysis using P40H resistivity (phase shift resistivity at 32 mHz with 40 inch spacing) and the P-wave velocity yields a gas hydrate saturation of 46 ± 15% and 46 ± 15% respectively, similar to those estimated using ring resistivity and P-wave velocity, but with quite different fracture dip angles. Differences in vertical resolution, depth of investigation, and a finite fracture dimension relative to the tool separation appear to contribute to this discrepancy. Forward modeling of anisotropic resistivity and velocity are essential to identify gas hydrate in fractures and to estimate accurate gas hydrate amounts.

  20. Heterogeneous upper mantle Ne, Ar and Xe isotopic compositions and a possible Dupal noble gas signature recorded in basalts from the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Parai, R.; Mukhopadhyay, S.; Standish, J. J.

    2012-12-01

    Variations in heavy noble gas (Ne, Ar, Xe) isotopic compositions provide unique insights into the nature of heterogeneities in the mantle. However, few precise constraints on mantle source heavy noble gas isotopic compositions are available due to ubiquitous shallow-level atmospheric contamination. As a result, the extent of heterogeneity in mid-ocean ridge basalt (MORB) mantle source Ne, Ar and Xe isotopic compositions is unknown. Basalts from the ultra-slow spreading Southwest Indian Ridge (SWIR) between 7°E and 25°E exhibit remarkable variability in He isotopic composition: SWIR 4He/3He spans half the total range observed in all mantle-derived basalts. Therefore, basalts from the SWIR provide a unique window into upper mantle heterogeneity and present an ideal opportunity to characterize variations in upper mantle heavy noble gas isotopic composition. Here we present new high-precision Ne, Ar and Xe isotopic compositions as well as He, CO2, Ne, Ar and Xe abundances measured in basalt glasses from the SWIR. After correcting the measured values for shallow-level atmospheric contamination, significant and systematic variations in mantle source Ne, Ar and Xe compositions are observed. We note that large variations in source 40Ar/36Ar and 129Xe/130Xe are observed in basalts removed from the influence of known hotspots, indicating a heterogeneous mid-ocean ridge basalt source. Thus, SWIR heavy noble gas data reveal a greater degree of source heterogeneity than is evident in the 4He/3He systematics alone. The observed heavy noble gas isotopic heterogeneities imply that the average MORB source 40Ar/36Ar and 129Xe/130Xe ratios are not yet well-determined. Variation in MORB source 40Ar/36Ar and 129Xe/130Xe at a given 4He/3He and 21Ne/22Ne may reflect heterogeneous recycling of atmospheric Ar and Xe. In particular, we find low mantle source 40Ar/36Ar and 129Xe/130Xe ratios in the eastern region of the study area, which may reflect the noble gas signature of the Dupal

  1. Efficient spectral broadening in the 100-W average power regime using gas-filled kagome HC-PCF and pulse compression.

    PubMed

    Emaury, Florian; Saraceno, Clara J; Debord, Benoit; Ghosh, Debashri; Diebold, Andreas; Gèrôme, Frederic; Südmeyer, Thomas; Benabid, Fetah; Keller, Ursula

    2014-12-15

    We present nonlinear pulse compression of a high-power SESAM-modelocked thin-disk laser (TDL) using an Ar-filled hypocycloid-core kagome hollow-core photonic crystal fiber (HC-PCF). The output of the modelocked Yb:YAG TDL with 127 W average power, a pulse repetition rate of 7 MHz, and a pulse duration of 740 fs was spectrally broadened 16-fold while propagating in a kagome HC-PCF containing 13 bar of static argon gas. Subsequent compression tests performed using 8.4% of the full available power resulted in a pulse duration as short as 88 fs using the spectrally broadened output from the fiber. Compressing the full transmitted power through the fiber (118 W) could lead to a compressed output of >100  W of average power and >100  MW of peak power with an average power compression efficiency of 88%. This simple laser system with only one ultrafast laser oscillator and a simple single-pass fiber pulse compressor, generating both high peak power >100  MW and sub-100-fs pulses at megahertz repetition rate, is very interesting for many applications such as high harmonic generation and attosecond science with improved signal-to-noise performance.

  2. Numerical study of sidewall filling for gas-fed pulse detonation engines

    NASA Astrophysics Data System (ADS)

    Rongrat, Wunnarat

    Pulse detonation engines for aerospace propulsion are required to operate at 50-100 Hz meaning that each pulse is 10-20 ms long. Filling of the engine and the related purging process become dominant due to their long duration compared to ignition and detonation wave propagation. This study uses ANSYS FLUENT to investigate the filling of a 1 m long tube with an internal diameter of 100 mm. Six different configurations were investigated with an endwall port and various sidewall arrangements, including stagger and inclination. A stoichiometric mixture of gaseous octane and air at STP was used to fill the tube at injection rates of 40, 150 and 250 m/s. Phase injection was also investigated and it showed performance improvements such as reduced lling time and reduced propellant escape from the exit.

  3. Resonant third harmonic generation of KrF laser in Ar gas

    SciTech Connect

    Rakowski, R.; Barna, A.; Suta, T.; Földes, I. B.; Bohus, J.; Szatmári, S.; Mikołajczyk, J.; Bartnik, A.; Fiedorowicz, H.; Verona, C.; Verona Rinati, G.; Margarone, D.; Nowak, T.; and others

    2014-12-15

    Investigations of emission of harmonics from argon gas jet irradiated by 700 fs, 5 mJ pulses from a KrF laser are presented. Harmonics conversion was optimized by varying the experimental geometry and the nozzle size. For the collection of the harmonic radiation silicon and solar-blind diamond semiconductor detectors equipped with charge preamplifiers were applied. The possibility of using a single-crystal CVD diamond detector for separate measurement of the 3rd harmonic in the presence of a strong pumping radiation was explored. Our experiments show that the earlier suggested 0.7% conversion efficiency can really be obtained, but only in the case when phase matching is optimized with an elongated gas target length corresponding to the length of coherence.

  4. NON-INTRUSIVE SENSOR FOR GAS FILL VERIFICATION OF INSULATED GLASS WINDOWS

    SciTech Connect

    Andrew Freedman; Paul L. Kebabian; Richard R. Romano; James Woodroffe

    2003-10-01

    A sensor capable of measuring the amount of oxygen (an unwanted component that is only present because of improper filling or seal failure) within an argon-filled insulated glass window has been designed, built and successfully tested. It operates by using the optical absorption of oxygen in the atmospheric A-band centered at 762 nm. Light emitted by an argon-filled surface glow discharge lamp is Zeeman-tuned on and off an oxygen absorption line using an AC-modulated electromagnet. In the presence of oxygen, the change in the measured intensity of the lamp, obtained using standard demodulation techniques, is proportional to the oxygen column density. Measurements using an industry-standard insulated glass window indicate that the sensor can measure the amount of oxygen in a nominally argon-filled IG window (with a window gap of 10 mm) with a precision of 0.50% oxygen using a 16 second integration time. This level of precision is well within the limits required by the IG window manufacturing industry for proper monitoring of newly manufactured window units.

  5. Second harmonic generation of spectrally broadened femtosecond ytterbium laser radiation in a gas-filled capillary

    SciTech Connect

    Didenko, N V; Konyashchenko, Aleksandr V; Kostryukov, P V; Losev, Leonid L; Tenyakov, S Yu

    2011-09-30

    A 300-fs radiation pulse of an ytterbium laser with a wavelength of 1030 nm and energy of 150 {mu}J were converted to a 15-fs pulse with a wavelength of 515 nm by broadening the emission spectrum in a capillary filled with xenon and by generating the second harmonic in a KDP crystal. The energy efficiency of the conversion was 30 %.

  6. Rare gas atomic number dependence of the hyperpolarizability for rare gas inserted fluorohydrides, HRgF (Rg = He, Ar, and Kr).

    PubMed

    Liu, Zhen-Bo; Li, Zhi-Ru; Zuo, Ming-Hui; Li, Qing-Zhong; Ma, Fang; Li, Zong-Jun; Chen, Guang-hui; Sun, Chia-Chung

    2009-07-28

    The three structures of rare gas inserted fluorohydrides HRgF (Rg = He, Ar, and Kr) with all real frequencies are obtained at the QCISD(T)/aug-cc-pVTZ level. The static first hyperpolarizabilities (beta(0)) at the QCISD/aug-cc-pVQZ level are 8 a.u. (HF), 384 a.u. (HHeF), 737 a.u. (HArF), and 465 a.u. (HKrF). The beta(0) value remarkably increases by about 50-90 times from 8 a.u. (HF) to 384-737 a.u. (HRgF) due to the inserted rare gas (Rg). The Rg atomic number dependence of beta(0) for HRgF (Rg = He, Ar, and Kr) is found at the first time. The order of beta(0) is unmonotonic to be HHeFHKrF, but not monotonic (HHeFgas atomic number dependence of beta(0) is unmonotonic. Furthermore, as the order of beta(0) is consistent with that of the difference between the ground and excited-state dipole moments (Deltamu), the Deltamu may be one mainly controlling factor of beta(0). The nature of H-Rg bond is also explored that special short H-He bond of 0.811 A is only a half single bond due to its Wiberg bond index of 0.51, while the long H-Ar and H-Kr bonds are almost single bond with the Wiberg bond index of about 0.8.

  7. Rare gas atomic number dependence of the hyperpolarizability for rare gas inserted fluorohydrides, HRgF (Rg=He, Ar, and Kr)

    NASA Astrophysics Data System (ADS)

    Liu, Zhen-Bo; Li, Zhi-Ru; Zuo, Ming-Hui; Li, Qing-Zhong; Ma, Fang; Li, Zong-Jun; Chen, Guang-hui; Sun, Chia-Chung

    2009-07-01

    The three structures of rare gas inserted fluorohydrides HRgF (Rg=He, Ar, and Kr) with all real frequencies are obtained at the QCISD(T)/aug-cc-pVTZ level. The static first hyperpolarizabilities (β0) at the QCISD/aug-cc-pVQZ level are 8 a.u. (HF), 384 a.u. (HHeF), 737 a.u. (HArF), and 465 a.u. (HKrF). The β0 value remarkably increases by about 50-90 times from 8 a.u. (HF) to 384-737 a.u. (HRgF) due to the inserted rare gas (Rg). The Rg atomic number dependence of β0 for HRgF (Rg=He, Ar, and Kr) is found at the first time. The order of β0 is unmonotonic to be HHeFHKrF, but not monotonic (HHeFgas atomic number dependence of β0 is unmonotonic. Furthermore, as the order of β0 is consistent with that of the difference between the ground and excited-state dipole moments (Δμ), the Δμ may be one mainly controlling factor of β0. The nature of H-Rg bond is also explored that special short H-He bond of 0.811 Å is only a half single bond due to its Wiberg bond index of 0.51, while the long H-Ar and H-Kr bonds are almost single bond with the Wiberg bond index of about 0.8.

  8. Picosecond pulses compression at 1053-nm center wavelength by using a gas-filled hollow-core fiber compressor

    NASA Astrophysics Data System (ADS)

    Huang, Zhi-Yuan; Wang, Ding; Leng, Yu-Xin; Dai, Ye

    2015-01-01

    We theoretically study the nonlinear compression of picosecond pulses with 10-mJ of input energy at the 1053-nm center wavelength by using a one-meter-long gas-filled hollow-core fiber (HCF) compressor and considering the third-order dispersion (TOD) effect. It is found that when the input pulse is about 1 ps/10 mJ, it can be compressed down to less than 20 fs with a high transmission efficiency. The gas for optimal compression is krypton gas which is filled in a HCF with a 400-μm inner diameter. When the input pulse duration is increased to 5 ps, it can also be compressed down to less than 100 fs efficiently under proper conditions. The results show that the TOD effect has little impact on picosecond pulse compression and the HCF compressor can be applied on compressing picosecond pulses efficiently with a high compression ratio, which will benefit the research of high-field laser physics. Project supported by the National Natural Science Foundation of China (Grant Nos. 11204328, 61221064, 61078037, 11127901, and 11134010), the National Basic Research Program of China (Grant No. 2011CB808101), the Commission of Science and Technology of Shanghai, China (Grant No. 12dz1100700), the Natural Science Foundation of Shanghai, China (Grant No. 13ZR1414800), and the International Science and Technology Cooperation Program of China (Grant No. 2011DFA11300).

  9. A comparison between micro hollow cathode discharges and atmospheric pressure plasma jets in Ar/O2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Lazzaroni, C.; Chabert, P.

    2016-12-01

    Using global models, micro hollow cathode discharges (MHCDs) are compared to radiofrequency atmospheric pressure plasma jets (APPJs) in terms of reactive oxygen species (ROS) production. Ar/O2 gas mixtures are investigated, typically with a small percentage of oxygen in argon. The same chemical reaction set, involving 17 species and 128 chemical reactions in the gas phase, is used for both devices, operated in the typical geometries previously published; the APPJ is driven by a radiofrequency voltage across a 1 mm gap, at atmospheric pressure, while the MHCD is driven by a DC voltage source, at 100 Torr and in a 400 μm hole. The MHCD may be operated either in the self-pulsing or in the normal (stationary) regime, depending on the driving voltage. The comparison shows that in both regimes, the MHCD produces larger amounts of \\text{O}2\\ast , while the APPJ produces predominantly reactive oxygen ground state species, \\text{O} and {{\\text{O}}3} . These large differences in ROS composition are mostly due to the higher plasma density produced in the MHCD. The difference in operating pressure is a second order effect.

  10. Effects of void size and gas content on electrical breakdown in lightweight, mechanically compliant, void-filled dielectrics

    NASA Astrophysics Data System (ADS)

    Anderson, R. A.; Lagasse, R. R.; Russick, E. M.; Schroeder, J. L.

    2002-03-01

    Dielectric potting materials (encapsulants) are used to prevent air breakdown in high-voltage electrical devices. We report breakdown strengths in void-filled encapsulants, stressed with unipolar voltage pulses of the order of 10 μs duration. High strengths, on the order of 100 kV mm-1, are measured under these test conditions. The materials studied include low-density open celled gel-derived foams with cell sizes of 4 μm or less, closed celled CO2-blown polystyrene and urethane foams, and epoxies containing 48 vol % of hollow glass microballoon (GMB) fillers. These last specimens varied the void gas (N2 or SO2) and also the void diameters (tens to hundreds of μm). Our measurements are thought to be directly sensitive to the rate of field-induced ionization events in the void gas; however, the breakdown strengths of the materials tested appeared to vary in direct proportion with the conventional Paschen-law gas-discharge inception threshold, the electric stress at which gas-ionization avalanches become possible. The GMB-epoxy specimens displayed this type of dependence of breakdown strength on the void-gas density and void size, but the measurements were an order of magnitude above the conventional predictions. Small-celled foams also showed increased breakdown strengths with decreased cell size, although their irregular void geometry prevented a direct comparison with the more uniformly structured microballoon-filled encapsulants. The experimental observations are consistent with a breakdown mechanism in which the discharge of a few voids can launch a full breakdown in the composite material.

  11. Analysis of Dicke Narrowing in Wall-Coated and Buffer-Gas-Filled Atomic Storage Cells,

    DTIC Science & Technology

    1986-04-01

    unshifted frequency. For the various reasons outlined the " particle in a box " analysis of motional narrowing in bufferless, wall-coated cells is...buffer gas or a wall, and consequently, one should not need two apparently distinct formalisms, buffer gas and particle in a box , to describe spectral line

  12. Efficient compression of the femtosecond pulses of an ytterbium laser in a gas-filled capillary

    SciTech Connect

    Konyashchenko, Aleksandr V; Losev, Leonid L; Tenyakov, S Yu

    2011-07-31

    A 290-fs radiation pulse of an ytterbium laser system with a central wavelength of 1028 nm and an energy of 145 {mu}J was compressed to a 27-fs pulse with an energy of 75 {mu}J. The compression was realised on the basis of the effect of pulse spectrum broadening in a xenon-filled glass capillary for a pulse repetition rate of 3kHz. (control of laser radiation parameters)

  13. Influence of gas pressure on high-order-harmonic generation of Ar and Ne

    SciTech Connect

    Wang Guoli; Jin Cheng; Le, Anh-Thu; Lin, C. D.

    2011-11-15

    We study the effect of gas pressure on the generation of high-order harmonics where harmonics due to individual atoms are calculated using the recently developed quantitative rescattering theory, and the propagation of the laser and harmonics in the medium is calculated by solving the Maxwell's wave equation. We illustrate that the simulated spectra are very sensitive to the laser focusing conditions at high laser intensity and high pressure since the fundamental laser field is severely reshaped during the propagation. By comparing the simulated results with several experiments we show that the pressure dependence can be qualitatively explained. The lack of quantitative agreement is tentatively attributed to the failure of the complete knowledge of the experimental conditions.

  14. Intense optical pulse compression with gas-filled hollow-core fibers and bulk materials in anomalous dispersion regime

    NASA Astrophysics Data System (ADS)

    Wang, Ding; Leng, Yuxin

    2013-10-01

    We numerically study the propagation dynamics and compression of ultrashort laser pulses in a hollow-core fiber (HCF) filled with noble gases at different carrier wavelengths from 1.8 μm to 3.9 μm. In the optimal parameter range, single-cycle or even sub-cycle pulses with clean spatial and temporal profiles can be obtained due to chirp compensation beyond 3rd order by bulk material. It is found that the intensity-dependent group velocity sets the upper limits on both the gas pressures and input pulse energies if a clean and well-compressed pulse is required only through compression with bulk materials. In order to use higher gas pressures and larger input energies, two ways are demonstrated to deal with the limitations imposed by the intensity-dependent group velocity.

  15. Surface modification of graphite-encapsulated iron nanoparticles by RF excited Ar/NH3 gas mixture plasma and their application to Escherichia coli capture

    NASA Astrophysics Data System (ADS)

    Viswan, Anchu; Chou, Han; Sugiura, Kuniaki; Nagatsu, Masaaki

    2016-09-01

    Graphite-encapsulated iron nanoparticles with an average diameter of 20 nm were synthesized using the DC arc discharge method. For biomedical application, the nanoparticles were functionalized with amino groups using an inductively coupled radio-frequency (RF) plasma. The Ar, NH3, and Ar/NH3 plasmas that were used for functionalization were diagnosed using optical emission spectroscopy, confirming the presence of the required elements. The best conditions for functionalization were optimized by changing various parameters. The pretreatment time with Ar plasma was varied from 0 to 12.5 min, the post-treatment time from 30 s to 3 min. The dependence of the RF power and the gas mixture ratio of Ar/NH3 on the amino group population was also analyzed. From Raman spectroscopy, x-ray photoelectron spectroscopy, and determination of absolute number of amino groups through chemical derivatization, it was found that 5 min of Ar pretreatment and 6%NH3/94%Ar plasma post-treatment for 3 min with an RF power of 80 W gives the best result of about 5  ×  104 amino groups per particle. The nanoparticles that were amino functionalized under optimized conditions and immobilized with an Escherichia coli (E.coli) antibody on their surface were incubated with E.coli bacteria to determine the efficiency of collection by direct culture assay.

  16. Molecular Gas-Filled Hollow Optical Fiber Lasers in the Near Infrared

    DTIC Science & Technology

    2012-01-12

    HOLLOW OPTICAL FIBER LASERS IN THE NEAR F A9550-08-l-0344 INFRARED Sb. GRANT NUMBER Sc. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Sd. PROJECT NUMBER...SUPPLEMENTARY NOTES 14. ABSTRACT We have demonstrated of a new class of optically pumped gas lasers inside a hollow-core photonic crystal fibers . Here, a...crystal fiber . These lasers are the first in a new class of infrared lasers based on the combination of hollow- fiber and optically pumped-gas

  17. Gas-Filled Hollow Core Fiber Lasers Based on Population Inversion

    DTIC Science & Technology

    2013-12-05

    iodine (I2) and pumped at ~ 532 nm was studied. Toward improved fiber transmission measurements, novel thulium /holmium fiber laser near 2 microns...transmission, we have demonstrated a novel thulium /holmium fiber laser near 2 microns. Abstract (short): Hollow-core Optical Fiber Gas LASer...measurements, novel thulium /holmium fiber laser near 2 microns were created. H. Schlossberg Hollow-Core Optical Fiber Gas Lasers K. Corwin et al

  18. Search for magnetic monopoles using proportional counters filled with helium gas

    NASA Technical Reports Server (NTRS)

    Cho, C.; Higashi, S.; Hiraoka, N.; Maruyama, A.; Ozaki, S.; Tsuji, K.

    1985-01-01

    Slow magnetic monopoles in cosmic rays have been searched at sea level with the detector which consists of seven layers of proportional counters filled with a mixture of He + 20% CH4. The velocities and the energy losses of the incident particles are measured. The upper limit of flux for the monopoles in the velocity range of 1 x 0.001 Beta 4 x 0.001 is 2.78 x 10 to the minus 12th power square centimeters sr sec of 90% confidence level.

  19. Generation of the organo-rare gas dications HCCRg2+ (Rg = Ar and Kr) in the reaction of acetylene dications with rare gases.

    PubMed

    Ascenzi, Daniela; Tosi, Paolo; Roithová, Jana; Ricketts, Claire L; Schröder, Detlef; Lockyear, Jessica F; Parkes, Michael A; Price, Stephen D

    2008-12-21

    Using doubly ionized acetylene as a superelectrophilic reagent, the new rare-gas compounds HCCAr2+ and HCCKr2+ have been prepared for the first time in hyperthermal collisions of mass-selected C2H2(2+) with neutral rare gases (Rg). However, electron transfer from the rare gas to the acetylene dication as well as proton transfer from C2H2(2+) to the rare gas efficiently compete with formation of HCCRg2+. The computational investigations show that the formation of HCCRg2+ from acetylene dication is endothermic with Rg = He, Ne, Ar and Kr and only weakly exothermic with Xe. These energetic factors, as well as the pronounced competition with the other reactive channels help to explain why HCCRg2+ is only observed with Rg = Ar and Kr.

  20. Collision Experiment of an Arched Plasma-Filled Flux Rope and a Target Cloud of Initially Neutral Gas

    NASA Astrophysics Data System (ADS)

    Wongwaitayakornkul, Pakorn; Bellan, Paul; Li, Hui; Li, Shengtai

    2016-10-01

    Shocks occur in the co-rotating interaction regions just beyond the solar corona, in the corona during CME events, and when the solar wind impacts Earth's magnetosphere. The Caltech solar loop experiment investigates shock physics by creating an arched plasma-filled flux rope that expands to collide with a pre-injected, initially-neutral gas. We focus the investigation on the situation of a heavy-gas plasma (Argon) impacting a much lighter neutral gas cloud (Hydrogen). The neutral gas target cloud ionizes immediately upon being impacted and plasma-induced shock waves propagate in the target cloud away from the impact region. Analysis of data from magnetic probes, Langmuir probes, a fast camera, and spectroscopic measurements will be presented. The measurements suggest that a thin, compressed, ionized layer of hydrogen is formed just downstream of the Argon plasma loop and that thin, supersonic shocks form further downstream and propagate obliquely away from the plasma loop. Numerical simulation of an ideal MHD plasma is underway to enable comparison of the measurements with the predictions of MHD theory.

  1. Gas-enabled resonance and rectified motion of a piston in a vibrated housing filled with a viscous liquid

    SciTech Connect

    Romero, Louis A.; Torczynski, John R.; Clausen, Jonathan R.; O'Hern, Timothy J.; Benavides, Gilbert L.

    2015-11-16

    Herein, we show how introducing a small amount of gas can completely change the motion of a solid object in a viscous liquid during vibration. We analyze an idealized system exhibiting this behavior: a piston moving in a liquid-filled housing, where the gaps between the piston and the housing are narrow and depend on the piston position. Recent experiments have shown that vibration causes some gas to move below the piston and the piston to subsequently move downward and compress its supporting spring. Herein, we analyze the analogous but simpler situation in which the gas regions are replaced by bellows with similar pressure-volume relationships. We show that these bellows form a spring (analogous to the pneumatic spring formed by the gas regions) which enables the piston and the liquid to oscillate in a mode that does not exist without this spring. This mode is referred to here as the Couette mode because the liquid in the gaps moves essentially in Couette flow (i.e., with almost no component of Poiseuille flow). Since Couette flow by itself produces extremely low damping, the Couette mode has a strong resonance. We show that, near this resonance, the dependence of the gap geometry on the piston position produces a large rectified (net) force on the piston during vibration. As a result, this force can be much larger than the piston weight and the strength of its supporting spring and is in the direction that decreases the flow resistance of the gap geometry.

  2. Identification of new astatine isotopes using the gas-filled magnetic separator, Sassy

    SciTech Connect

    Yashita, S.

    1983-01-01

    A He-filled on-line separator system was built at the SuperHILAC and used to study the fusion products in the reaction /sup 56/Fe + /sup 141/Pr. The new neutron-deficient isotopes /sup 194/At and /sup 195/At were produced in this bombardment as three- and two-neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are 7.20 +/- 0.02 MeV and 180 +/- 80 msec for /sup 194/At, and 7.12 +/- 0.02 MeV and 200 +/- 100 msec for /sup 195/At.

  3. Identification of new astatine isotopes using the gas-filled magnetic separator, SASSY

    SciTech Connect

    Yashita, S.

    1984-02-01

    A He-filled on-line mass separator system was built at the SuperHILAC and used to study the fusion products in the reaction /sup 56/Fe + /sup 141/Pr. The new neutron-deficient isotopes /sup 194/At and /sup 195/At were produced in this bombardment as three- and two- neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are 7.20 +- 0.02 MeV and 180 +- 80 msec for /sup 194/At, and 7.12 +- 0.02 MeV and 200 +- 100 msec for /sup 195/At. 66 references.

  4. Study of x-rays produced from debris-free sources with Ar, Kr and Kr/Ar mixture linear gas jets irradiated by UNR Leopard laser beam with fs and ns pulse duration

    NASA Astrophysics Data System (ADS)

    Kantsyrev, V. L.; Schultz, K. A.; Shlyaptseva, V. V.; Safronova, A. S.; Shrestha, I. K.; Petrov, G. M.; Moschella, J. J.; Petkov, E. E.; Stafford, A.; Cooper, M. C.; Weller, M. E.; Cline, W.; Wiewior, P.; Chalyy, O.

    2016-06-01

    Experiments of x-ray emission from Ar, Kr, and Ar/Kr gas jet mixture were performed at the UNR Leopard Laser Facility operated with 350 fs pulses at laser intensity of 2 × 1019 W/cm2 and 0.8 ns pulses at an intensity of 1016 W/cm2. Debris free x-ray source with supersonic linear nozzle generated clusters/monomer jet with an average density of ≥1019 cm-3 was compared to cylindrical tube subsonic nozzle, which produced only monomer jet with average density 1.5-2 times higher. The linear (elongated) cluster/gas jet provides the capability to study x-ray yield anisotropy and laser beam self-focusing with plasma channel formation that are interconnecting with efficient x-ray generation. Diagnostics include x-ray diodes, pinhole cameras and spectrometers. It was observed that the emission in the 1-9 keV spectral region was strongly anisotropic depending on the directions of laser beam polarization for sub-ps laser pulse and supersonic linear jet. The energy yield in the 1-3 keV region produced by a linear nozzle was an order of magnitude higher than from a tube nozzle. Non-LTE models and 3D molecular dynamic simulations of Ar and Kr clusters irradiated by sub-ps laser pulses have been implemented to analyze obtained data. A potential evidence of electron beam generation in jets' plasma was discussed. Note that the described debris-free gas-puff x-ray source can generate x-ray pulses in a high repetition regime. This is a great advantage compared to solid laser targets.

  5. Absolute CF{sub 2} density and gas temperature measurements by absorption spectroscopy in dual-frequency capacitively coupled CF{sub 4}/Ar plasmas

    SciTech Connect

    Liu, Wen-Yao; Xu, Yong Peng, Fei; Gong, Fa-Ping; Li, Xiao-Song; Zhu, Ai-Min; Liu, Yong-Xin; Wang, You-Nian

    2014-10-15

    Broadband ultraviolet absorption spectroscopy has been used to determine the CF{sub 2} radical density in dual-frequency capacitively coupled CF{sub 4}/Ar plasmas, using the CF{sub 2} A{sup ~1}B{sub 1}←X{sup ~1}A{sub 1} system of absorption spectrum. The rotational temperature of ground state CF{sub 2} and excited state CF was also estimated by using A{sup ~1}B{sub 1}←X{sup ~1}A{sub 1} system and B{sup 2}Δ−X{sup 2}Π system, respectively. The translational gas temperature was deduced from the Doppler width of the Ar{sup *}({sup 3}P{sub 2}) and Ar{sup *}({sup 3}P{sub 0}) metastable atoms absorption line by using the tunable diode laser absorption spectroscopy. The rotational temperatures of the excited state CF are about 100 K higher than those of ground state CF{sub 2}, and about 200 K higher than the translational gas temperatures. The dependences of the radical CF{sub 2} density, electron density, electron temperature, rotational temperature, and gas temperature on the high frequency power and pressure have been analyzed. Furthermore, the production and loss mechanisms of CF{sub 2} radical and the gas heating mechanisms have also been discussed.

  6. Absolute CF2 density and gas temperature measurements by absorption spectroscopy in dual-frequency capacitively coupled CF4/Ar plasmas

    NASA Astrophysics Data System (ADS)

    Liu, Wen-Yao; Xu, Yong; Liu, Yong-Xin; Peng, Fei; Gong, Fa-Ping; Li, Xiao-Song; Zhu, Ai-Min; Wang, You-Nian

    2014-10-01

    Broadband ultraviolet absorption spectroscopy has been used to determine the CF2 radical density in dual-frequency capacitively coupled CF4/Ar plasmas, using the CF2 A ˜ 1 B 1 ← X ˜ 1 A 1 system of absorption spectrum. The rotational temperature of ground state CF2 and excited state CF was also estimated by using A ˜ 1 B 1 ← X ˜ 1 A 1 system and B 2 Δ - X 2 Π system, respectively. The translational gas temperature was deduced from the Doppler width of the Ar*(3P2) and Ar*(3P0) metastable atoms absorption line by using the tunable diode laser absorption spectroscopy. The rotational temperatures of the excited state CF are about 100 K higher than those of ground state CF2, and about 200 K higher than the translational gas temperatures. The dependences of the radical CF2 density, electron density, electron temperature, rotational temperature, and gas temperature on the high frequency power and pressure have been analyzed. Furthermore, the production and loss mechanisms of CF2 radical and the gas heating mechanisms have also been discussed.

  7. The influence of variations in biophysical conditions on hemolysis near ultrasonically activated gas-filled micropores

    SciTech Connect

    Miller, D.L.; Thomas, R.M. )

    1990-05-01

    Hemolysis induced by 1.9-MHz ultrasound in 0.5% suspensions of canine erythrocytes with 3.7-{mu}m-diam micropore-trapped gas bodies was investigated for a variety of biophysical conditions. For isotonic media, hemolysis increased with exposure duration but did not greatly change with exposure temperature, or prior heat treatment. The temperature results were especially interesting because increased temperatures might have been expected to increase the sensitivity of the cells to the ultrasonically activated gas bodies. Variations in osmolarity had little influence on the results. Increasing the viscosity of the medium decreased the effect, and this did not seem to depend on the molecular weight of the dextran additive. A medium with elevated mass density seemed to increase the effectiveness of the exposures. This condition eliminated the density difference between the cells and the medium, and might have been expected to reduce the effectiveness of the exposures, because the radiation force, which theoretically gathers cells to the gas bodies, is minimized for such conditions. This information should aid in developing refinements to the theoretical understanding of low-intensity ultrasonic bioeffects.

  8. Fabrication and testing of gas-filled targets for large-scale plasma experiments on nova

    SciTech Connect

    Stone, G.F.; Rivers, C.J.; Spragge, M.R.; Wallace, R.J.

    1996-06-01

    The proposed next-generation ICF facility, the National Ignition Facility (NIF) is designed to produce energy gain from x-ray heated {open_quotes}indirect-drive{close_quotes} fuel capsules. For indirect-drive targets, laser light heats the inside of the Au hohlraum wall and produces x rays which in turn heat and implode the capsule to produce fusion conditions in the fuel. Unlike Nova targets, in NIF-scale targets laser light will propagate through several millimeters of gas, producing a plasma, before impinging upon the Au hohlraum wall. The purpose of the gas-produced plasma is to provide sufficient pressure to keep the radiating Au surface from expanding excessively into the hohlraum cavity. Excessive expansion of the Au wall interacts with the laser pulse and degrades the drive symmetry of the capsule implosion. The authors have begun an experimental campaign on the Nova laser to study the effect of hohlraum gas on both laser-plasma interaction and implosion symmetry. In their current NIF target design, the calculated plasma electron temperature is T{sub e} {approx} 3 keV and the electron density is N{sub e} {approx} 10{sup 21}cm{sup {minus}3}.

  9. High-performance, non-CFC-based thermal insulation: Gas filled panels

    SciTech Connect

    Griffith, B.T.; Arasteh, D.; Selkowitz, S.

    1992-04-01

    Because of the forthcoming phase-out of CFCs and to comply with the more stringent building and appliance energy-use standards, researchers in industry and in the public sector are pursuing the development of non-CFC-based, high-performance insulation materials. This report describes the results of research and development of one alternative insulation material: highly insulating GFPs. GFPs insulate in two ways: by using a gas barrier envelope to encapsulate a low-thermal-conductivity gas or gas mixture (at atmospheric pressure), and by using low-emissivity baffles to effectively eliminate convective and radiative heat transfer. This approach has been used successfully to produce superinsulated windows. Unlike foams or fibrous insulations, GFPs are not a homogeneous material but rather an assembly of specialized components. The wide range of potential applications of GFPs (appliances, manufactured housing, site-built buildings, refrigerated transport, and so on) leads to several alternative embodiments. While the materials used for prototype GFPs are commercially available, further development of components may be necessary for commercial products. With the exception of a description of the panels that were independently tested, specific information concerning panel designs and materials is omitted for patent reasons; this material is the subject of a patent application by Lawrence Berkeley Laboratory.

  10. Spectroscopic and modeling investigations of the gas-phase chemistry and composition in microwave plasma activated B2H6/Ar/H2 mixtures.

    PubMed

    Ma, Jie; Richley, James C; Davies, David R W; Cheesman, Andrew; Ashfold, Michael N R; Mankelevich, Yuri A

    2010-02-25

    This paper describes a three-pronged study of microwave (MW) activated B(2)H(6)/Ar/H(2) plasmas as a precursor to diagnosis of the B(2)H(6)/CH(4)/Ar/H(2) plasmas used for the chemical vapor deposition of B-doped diamond. Absolute column densities of B atoms and BH radicals have been determined by cavity ring-down spectroscopy as a function of height (z) above a molybdenum substrate and of the plasma process conditions (B(2)H(6) and Ar partial pressures, total pressure, and supplied MW power). Optical emission spectroscopy has been used to explore variations in the relative densities of electronically excited BH, H, and H(2) species as a function of the same process conditions and of time after introducing B(2)H(6) into a pre-existing Ar/H(2) plasma. The experimental measurements are complemented by extensive 2-D(r, z) modeling of the plasma chemistry, which results in refinements to the existing B/H chemistry and thermochemistry and demonstrates the potentially substantial loss of gas-phase BH(x) species through reaction with trace quantities of air/O(2) in the process gas mixture and heterogeneous processes occurring at the reactor wall.

  11. Photosynthetic Gas Exchange Characteristics of Wheat Flag Leaf Blades and Sheaths during Grain Filling

    PubMed Central

    Araus, José L.; Tapia, Luis

    1987-01-01

    The rate of net CO2 assimilation (A), the stomatal (gs) and residual (gr) conductances to CO2, the intercellular CO2 concentration, the CO2 compensation points at 21% O2 (Γ21) and at 2% O2 (Γ2), and the amounts of dry matter, nitrogen, and carbohydrates were determined, from anthesis through grain filling, in the flag leaf blade and sheath of spring wheat (Triticum aestivum L. cv Kolibri). The nitrogen content and the rate of net CO2 assimilation declined slowly until the onset of senescence in both organs, about 3 weeks after anthesis. During senescence the reduction of A in both organs was not primarily caused by a decrease in gs; the main factor is the decrease in gr. From values of Γ21 and Γ2 it is suggested that the rate of respiration in the light contributing to the CO2 compensation point is higher in sheaths than in blades irrespective of the O2 level considered. The role of sheaths storing and later transporting assimilates to the developing grains seems to be more important for shoot yield than that of sheaths functioning as photosynthetic organs after the onset of senescence occurs. It is suggested that accumulation of carbohydrates in leaves might somehow trigger senescence in the flag leaf blade and sheath simultaneously. PMID:16665757

  12. Possible health effects of liquefied petroleum gas on workers at filling and distribution stations of Gaza governorates.

    PubMed

    Sirdah, M M; Al Laham, N A; El Madhoun, R A

    2013-03-01

    Liquefied petroleum gas (LPG) is widely used in the Gaza Strip for domestic purposes, in agriculture and industry and, illegally, in cars. This study aimed to identify possible health effects on workers exposed to LPG in Gaza governorates. Data were collected by a questionnaire interview, and haematological and biochemical analyses of venous blood samples were made from 30 workers at filling and distribution stations and 30 apparently healthy controls. Statistically significant differences were found in all self-reported health-related complaints among LPG workers versus controls. LPG workers had significantly higher values of red blood cell counts, haemoglobin, haematocrit mean corpuscular haemoglobin and platelet counts. They also had significantly higher values of kidney function tests (urea, creatinine and uric acid) and liver function enzyme activities (aspartate aminotransferase and alanine aminotransferase). LPG workers at Gaza Strip petroleum stations are at higher risk for health-related symptoms and clinical abnormalities.

  13. Effect of a transverse magnetic field on the generation of electron beams in the gas-filled diode

    NASA Astrophysics Data System (ADS)

    Baksht, E. H.; Burachenko, A. G.; Erofeev, M. V.; Kostyrya, I. D.; Lomaev, M. I.; Rybka, D. V.; Tarasenko, V. F.

    2008-06-01

    The effect of a transverse magnetic field (0.080 and 0.016 T) on generation of an electron beam in the gas-filled diode is experimentally investigated. It is shown that, at voltage U = 25 kV across the diode and a low helium pressure (45 Torr), the transverse magnetic field influences the beam current amplitude behind a foil and its distribution over the foil cross section. At elevated pressures and under the conditions of ultrashort avalanche electron beam formation in helium, nitrogen, and air, the transverse magnetic field (0.080 and 0.016 T) has a minor effect on the amplitude and duration of the beam behind the foil. It is established that, when the voltage of the pulse generator reaches several hundreds of kilovolts, some runaway electrons (including the electrons from the discharge plasma near the cathode) are incident on the side walls of the diode.

  14. Magnetic discharge accelerating diode for the gas-filled pulsed neutron generators based on inertial confinement of ions

    NASA Astrophysics Data System (ADS)

    Kozlovskij, K. I.; Shikanov, A. E.; Vovchenko, E. D.; Shatokhin, V. L.; Isaev, A. A.; Martynenko, A. S.

    2016-09-01

    The paper deals with magnetic discharge diode module with inertial electrostatic ions confinement for the gas-filled pulsed neutron generators. The basis of the design is geometry with the central hollow cathode surrounded by the outer cylindrical anode and electrodes made of permanent magnets. The induction magnitude about 0.1-0.4 T in the central region of the discharge volume ensures the confinement of electrons in the space of hollow (virtual) cathode and leads to space charge compensation of accelerated ions in the centre. The research results of different excitation modes in pulsed high-voltage discharge are presented. The stable form of the volume discharge preserveing the shape and amplitude of the pulse current in the pressure range of 10-3-10-1 Torr and at the accelerating voltage up to 200 kV was observed.

  15. Detector Calibration to Spontaneous Fission for the Study of Superheavy Elements Using Gas-Filled Recoil Ion Separator

    NASA Astrophysics Data System (ADS)

    Takeyama, Mirei; Kaji, Daiya; Morimoto, Kouji; Wakabayashi, Yasuo; Tokanai, Fuyuki; Morita, Kosuke

    Detector response to spontaneous fission (SF) of heavy nuclides produced in the 206Pb(48Ca,2n)252No reaction was investigated using a gas-filled recoil ion separator (GARIS). Kinetic energy distributions of the SF originating from 252No were observed by tuning implantation depth of evaporation residue (ER) to the detector. The focal plane detector used in the GARIS experiments was well calibrated by comparing with the known total kinetic energy (TKE) of SF due to 252No. The correction value for the TKE calculation was deduced as a function of the implantation depth of 252No to the detector. Furthermore, we have investigated the results by comparing with those obtained by a computer simulation using the particle and heavy ion transport code system (PHITS).

  16. X-ray imaging of uniform large scale-length plasmas created from gas-filled targets on Nova

    SciTech Connect

    Kalantar, D.H.; MacGowan, B.J.; Bernat, T.P.

    1994-05-01

    We report on the production and characterization of large scale-length plasmas created by illuminating gas-filled thin-walled balloon-like targets using the Nova laser. The targets consisted of a 4--5000 {angstrom} skin surrounding 1 atm of neopentane which when ionized becomes a plasma with 10{sup 21} electrons/cm{sup 3}. Results are presented from x-ray imaging used to evaluate the uniformity of the plasma. The most uniform plasmas were produced by illuminating the target with large converging beams that overlapped to cover most of the surface of the gasbag. An alternate focus geometry using small beam spots resulted in a less uniform plasma with low density holes in it.

  17. Two techniques for temporal pulse compression in gas-filled hollow-core kagomé photonic crystal fiber.

    PubMed

    Mak, K F; Travers, J C; Joly, N Y; Abdolvand, A; Russell, P St J

    2013-09-15

    We demonstrate temporal pulse compression in gas-filled kagomé hollow-core photonic crystal fiber (PCF) using two different approaches: fiber-mirror compression based on self-phase modulation under normal dispersion, and soliton effect self-compression under anomalous dispersion with a decreasing pressure gradient. In the first, efficient compression to near-transform-limited pulses from 103 to 10.6 fs was achieved at output energies of 10.3 μJ. In the second, compression from 24 to 6.8 fs was achieved at output energies of 6.6 μJ, also with near-transform-limited pulse shapes. The results illustrate the potential of kagomé-PCF for postprocessing the output of fiber lasers. We also show that, using a negative pressure gradient, ultrashort pulses can be delivered directly into vacuum.

  18. Effect of the gas temperature and pressure on the nucleation time of particles in low pressure Ar-C2H2 rf plasmas

    NASA Astrophysics Data System (ADS)

    Lin, Jiashu; Henault, Marie; Orazbayev, Sagi; Boufendi, Laïa; Takahashi, Kazuo; Al Farabi Kazakh National University Collaboration; Kyoto Institute Of Technology Team; Gremi Team

    2016-09-01

    Particle formation in low pressure plasmas is a 3-step process. The first one corresponds to the nucleation and growth of nano-crystallites by ion-molecular reactions, the agglomeration phase to form large particles, and the growth by radical deposition on the particle surface. The nucleation phase was demonstrated to be sensitive to gas temperature and pressure. In this work, time of nucleation phase of particles formation in low pressure cold rf C2H2/Ar plasmas studied by varying gas temperature from 265 K to 375 K, gas pressure from 0.4 mbar to 0.8 mbar and rf power from 6 W to 20 W. The ratio of C2H2/Ar is fixed to 2/98 in terms of pressure. Several previous works reported that particle formation takes a few sec at room temperature in C2 H2 plasmas and the time is much shorter than 0.1 s in SiH4 plasmas. Time evolution of self-bias voltage was mainly used to determine nucleation time. The self-bias voltage was modified by phase transition between the steps from nucleation to coagulation. The experimental results showed that the nucleation time increased with gas temperature, decreased with gas pressure and discharge power. At constant gas pressure of 0.4 mbar and discharge power of 6 W, for example, the nucleation time increased from 5 sec to 30 sec with increas

  19. Filling in the Roadmap for Self-Consistent Electron Cloud and Gas Modeling

    SciTech Connect

    Vay, J; Furman, M A; Seidl, P A; Cohen, R H; Friedman, A; Grote, D P; Covo, M K; Molvik, A W; Stoltz, P H; Veitzer, S; Verboncoeur, J

    2005-10-11

    Electron clouds and gas pressure rise limit the performance of many major accelerators. A multi-laboratory effort to understand the underlying physics via the combined application of experiment, theory, and simulation is underway. We present here the status of the simulation capability development, based on a merge of the three-dimensional parallel Particle-In-Cell (PIC) accelerator code WARP and the electron cloud code POSINST, with additional functionalities. The development of the new capability follows a ''roadmap'' describing the different functional modules, and their inter-relationships, that are ultimately needed to reach self-consistency. Newly developed functionalities include a novel particle mover bridging the time scales between electron and ion motion, a module to generate neutrals desorbed by beam ion impacts at the wall, and a module to track impact ionization of the gas by beam ions or electrons. Example applications of the new capability to the modeling of electron effects in the High Current Experiment (HCX) are given.

  20. Effect of stratified inequality of blood flow on gas exchange in liquid-filled lungs.

    NASA Technical Reports Server (NTRS)

    West, J. B.; Maloney, J. E.; Castle, B. L.

    1972-01-01

    This investigation set out to answer two questions: (1) are the distal alveoli in the terminal lung units less well perfused than the proximal alveoli, i.e., is there stratification of blood flow; and (2) if so, does this enhance gas exchange in the presence of stratified inequality of ventilation. Excised dog lungs were ventilated with saline and perfused with blood. Following single inspirations of xenon 133 in saline and various periods of breath holding, the expired xenon concentration against volume was measured and it confirmed marked stratified inequality of ventilation under these conditions. By measuring the rate of depletion of xenon from alveoli during a period of blood flow, we showed that the alveoli which emptied at the end of expiration had 16% less blood flow than those exhaling earlier. However, by measuring the xenon concentration in pulmonary venous blood, we found that about 10% less tracer was transferred from the alveoli into the blood when the inspired xenon was stratified within the respiratory zone. Thus while stratification of blood flow was confirmed, it was shown to impair rather than enhance the efficiency of gas transfer.

  1. Simulations of Ar gas-puff Z-pinch radiation sources with double shells and central jets on the Z generator

    SciTech Connect

    Tangri, V.; Harvey-Thompson, Adam James; Giuliani, J. L.; Thornhill, J. W.; Velikovich, A. L.; Apruzese, J. P.; Quart, N. D.; DasGupta, A.; Jones, Brent M.; Jennings, Christopher Ashley

    2016-10-19

    Radiation-magnetohydrodynamic simulations using the non-LTE Mach2-TCRE code in (r,z) geometry are performed for two pairs of recent Ar gas-puff Z-pinch experiments on the refurbished Z generator with an 8 cm diameter nozzle. One pair of shots had an outer-to-inner shell mass ratio of 1:1.6 and a second pair had a ratio of 1:1.

  2. Simulations of Ar gas-puff Z-pinch radiation sources with double shells and central jets on the Z generator

    DOE PAGES

    Tangri, V.; Harvey-Thompson, Adam James; Giuliani, J. L.; ...

    Radiation-magnetohydrodynamic simulations using the non-LTE Mach2-TCRE code in (r,z) geometry are performed for two pairs of recent Ar gas-puff Z-pinch experiments on the refurbished Z generator with an 8 cm diameter nozzle. One pair of shots had an outer-to-inner shell mass ratio of 1:1.6 and a second pair had a ratio of 1:1.

  3. Gas-enabled resonance and rectified motion of a piston in a vibrated housing filled with a viscous liquid

    DOE PAGES

    Romero, Louis A.; Torczynski, John R.; Clausen, Jonathan R.; ...

    2015-11-16

    Herein, we show how introducing a small amount of gas can completely change the motion of a solid object in a viscous liquid during vibration. We analyze an idealized system exhibiting this behavior: a piston moving in a liquid-filled housing, where the gaps between the piston and the housing are narrow and depend on the piston position. Recent experiments have shown that vibration causes some gas to move below the piston and the piston to subsequently move downward and compress its supporting spring. Herein, we analyze the analogous but simpler situation in which the gas regions are replaced by bellowsmore » with similar pressure-volume relationships. We show that these bellows form a spring (analogous to the pneumatic spring formed by the gas regions) which enables the piston and the liquid to oscillate in a mode that does not exist without this spring. This mode is referred to here as the Couette mode because the liquid in the gaps moves essentially in Couette flow (i.e., with almost no component of Poiseuille flow). Since Couette flow by itself produces extremely low damping, the Couette mode has a strong resonance. We show that, near this resonance, the dependence of the gap geometry on the piston position produces a large rectified (net) force on the piston during vibration. As a result, this force can be much larger than the piston weight and the strength of its supporting spring and is in the direction that decreases the flow resistance of the gap geometry.« less

  4. High frequency characteristics of FeCoAlO thin films fabricated with asymmetric target at different Ar gas flow rates

    NASA Astrophysics Data System (ADS)

    Zheng, Fu; Luo, Feilong; Lou, Yuanfu; Wang, Ying; Bai, Jianmin; Wei, Dan; Liu, Xiaoxi; Wei, Fulin

    2012-04-01

    FeCoAlO thin films with good soft magnetic properties were fabricated by using RF magnetron sputtering. In order to obtain good high-frequency performance, the in-plane uniaxial anisotropy was tuned by combining the effects of in situ magnetic field and the gradient of Al-O concentration. The composition gradient was controlled by using an asymmetric target and different Ar gas flow rates changing from 5 sccm to 17.5 sccm. It was found that at the range of Ar gas flow rate from 7.5 sccm to 15 sccm, the films showed an excellent high-frequency performance: the resonance frequency was beyond 3.0 GHz and the real permeability μ' had a high value of ˜200 at low-frequency side. In particular, the film prepared at the Ar gas flow rate of 15 sccm showed a resonance frequency of 4.0 GHz. Large resonance frequency can be attributed to the high in-plane uniaxial anisotropy field which was induced by stress and the external magnetic field. The high values of permeability and resonance frequency enable the FeCoAlO thin films to be one of the important candidates for microwave applications.

  5. Development of an AMS method to study oceanic circulation characteristics using cosmogenic 39Ar

    USGS Publications Warehouse

    Collon, P.H.; Bichler, M.; Caggiano, J.; Cecil, L.D.; El, Masri Y.; Golser, R.; Jiang, C.L.; Heinz, A.; Henderson, D.; Kutschera, W.; Lehmann, B.E.; Leleux, P.; Loosli, H.H.; Pardo, R.C.; Paul, M.; Rehm, K.E.; Schlosser, P.; Scott, R.H.; Smethie, W.M.; Vondrasek, R.

    2004-01-01

    Initial experiments at the ATLAS facility [Nucl. Instr. and Meth. B 92 (1994) 241] resulted in a clear detection of cosmogenic 39Ar signal at the natural level. The present paper summarizes the recent developments of 39Ar AMS measurements at ATLAS: the use of an electron cyclotron resonance (ECR) positive ion source equipped with a special quartz liner to reduce 39K background, the development of a gas handling system for small volume argon samples, the acceleration of 39Ar8+ ions to 232 MeV, and the final separation of 39Ar from 39K in a gas-filled spectrograph. The first successful AMS measurements of 39Ar in ocean water samples from the Southern Atlantic ventilation experiment (SAVE) are reported. Published by Elsevier B.V.

  6. The role of the gas/plasma plume and self-focusing in a gas-filled capillary discharge waveguide for high-power laser-plasma applications

    SciTech Connect

    Ciocarlan, C.; Wiggins, S. M.; Islam, M. R.; Ersfeld, B.; Abuazoum, S.; Wilson, R.; Aniculaesei, C.; Welsh, G. H.; Vieux, G.; Jaroszynski, D. A.

    2013-09-15

    The role of the gas/plasma plume at the entrance of a gas-filled capillary discharge plasma waveguide in increasing the laser intensity has been investigated. Distinction is made between neutral gas and hot plasma plumes that, respectively, develop before and after discharge breakdown. Time-averaged measurements show that the on-axis plasma density of a fully expanded plasma plume over this region is similar to that inside the waveguide. Above the critical power, relativistic and ponderomotive self-focusing lead to an increase in the intensity, which can be nearly a factor of 2 compared with the case without a plume. When used as a laser plasma wakefield accelerator, the enhancement of intensity can lead to prompt electron injection very close to the entrance of the waveguide. Self-focusing occurs within two Rayleigh lengths of the waveguide entrance plane in the region, where the laser beam is converging. Analytical theory and numerical simulations show that, for a density of 3.0 × 10{sup 18} cm{sup −3}, the peak normalized laser vector potential, a{sub 0}, increases from 1.0 to 1.85 close to the entrance plane of the capillary compared with a{sub 0} = 1.41 when the plume is neglected.

  7. Microcontroller based system for electrical breakdown time delay measurement in gas-filled devices

    NASA Astrophysics Data System (ADS)

    Pejović, Milić M.; Denić, Dragan B.; Pejović, Momčilo M.; Nešić, Nikola T.; Vasović, Nikola

    2010-10-01

    This paper presents realization of a digital embedded system for measuring electrical breakdown time delay. The proposed system consists of three major parts: dc voltage supply, analog subsystem, and a digital subsystem. Any dc power source with the range from 100 to 1000 V can be used in this application. The analog subsystem should provide fast and accurate voltage switching on the testing device as well as transform the signals that represent the voltage pulse on the device and the device breakdown into the form suitable for detection by a digital subsystem. The insulated gate bipolar transistor IRG4PH40KD driven by TC429 MOSFET driver is used for high voltage switching on the device. The aim of a digital subsystem is to detect the signals from the analog subsystem and to measure the elapsed time between their occurrences. Moreover, the digital subsystem controls various parameters that influence time delay and provides fast data storage for a large number of measured data. For this propose, we used the PIC18F4550 microcontroller with a full-speed compatible universal serial bus (USB) engine. Operation of this system is verified on different commercial and custom made gas devices with different structure and breakdown mechanisms. The electrical breakdown time delay measurements have been carried out as a function of several parameters, which dominantly influence electrical breakdown time delay. The obtained results have been verified using statistical methods, and they show good agreement with the theory. The proposed system shows good repeatability, sensitivity, and stability for measuring the electrical breakdown time delay.

  8. Microcontroller based system for electrical breakdown time delay measurement in gas-filled devices

    SciTech Connect

    Pejovic, Milic M.; Denic, Dragan B.; Pejovic, Momcilo M.; Nesic, Nikola T.; Vasovic, Nikola

    2010-10-15

    This paper presents realization of a digital embedded system for measuring electrical breakdown time delay. The proposed system consists of three major parts: dc voltage supply, analog subsystem, and a digital subsystem. Any dc power source with the range from 100 to 1000 V can be used in this application. The analog subsystem should provide fast and accurate voltage switching on the testing device as well as transform the signals that represent the voltage pulse on the device and the device breakdown into the form suitable for detection by a digital subsystem. The insulated gate bipolar transistor IRG4PH40KD driven by TC429 MOSFET driver is used for high voltage switching on the device. The aim of a digital subsystem is to detect the signals from the analog subsystem and to measure the elapsed time between their occurrences. Moreover, the digital subsystem controls various parameters that influence time delay and provides fast data storage for a large number of measured data. For this propose, we used the PIC18F4550 microcontroller with a full-speed compatible universal serial bus (USB) engine. Operation of this system is verified on different commercial and custom made gas devices with different structure and breakdown mechanisms. The electrical breakdown time delay measurements have been carried out as a function of several parameters, which dominantly influence electrical breakdown time delay. The obtained results have been verified using statistical methods, and they show good agreement with the theory. The proposed system shows good repeatability, sensitivity, and stability for measuring the electrical breakdown time delay.

  9. Microcontroller based system for electrical breakdown time delay measurement in gas-filled devices.

    PubMed

    Pejović, Milić M; Denić, Dragan B; Pejović, Momčilo M; Nešić, Nikola T; Vasović, Nikola

    2010-10-01

    This paper presents realization of a digital embedded system for measuring electrical breakdown time delay. The proposed system consists of three major parts: dc voltage supply, analog subsystem, and a digital subsystem. Any dc power source with the range from 100 to 1000 V can be used in this application. The analog subsystem should provide fast and accurate voltage switching on the testing device as well as transform the signals that represent the voltage pulse on the device and the device breakdown into the form suitable for detection by a digital subsystem. The insulated gate bipolar transistor IRG4PH40KD driven by TC429 MOSFET driver is used for high voltage switching on the device. The aim of a digital subsystem is to detect the signals from the analog subsystem and to measure the elapsed time between their occurrences. Moreover, the digital subsystem controls various parameters that influence time delay and provides fast data storage for a large number of measured data. For this propose, we used the PIC18F4550 microcontroller with a full-speed compatible universal serial bus (USB) engine. Operation of this system is verified on different commercial and custom made gas devices with different structure and breakdown mechanisms. The electrical breakdown time delay measurements have been carried out as a function of several parameters, which dominantly influence electrical breakdown time delay. The obtained results have been verified using statistical methods, and they show good agreement with the theory. The proposed system shows good repeatability, sensitivity, and stability for measuring the electrical breakdown time delay.

  10. Smoothing single-crystalline SiC surfaces by reactive ion etching using pure NF{sub 3} and NF{sub 3}/Ar mixture gas plasmas

    SciTech Connect

    Tasaka, Akimasa; Kotaka, Yuki; Oda, Atsushi; Saito, Morihiro; Tojo, Tetsuro; Inaba, Minoru

    2014-09-01

    In pure NF{sub 3} plasma, the etching rates of four kinds of single-crystalline SiC wafer etched at NF{sub 3} pressure of 2 Pa were the highest and it decreased with an increase in NF{sub 3} pressure. On the other hand, they increased with an increase in radio frequency (RF) power and were the highest at RF power of 200 W. A smooth surface was obtained on the single-crystalline 4H-SiC after reactive ion etching at NF{sub 3}/Ar gas pressure of 2 Pa and addition of Ar to NF{sub 3} plasma increased the smoothness of SiC surface. Scanning electron microscopy observation revealed that the number of pillars decreased with an increase in the Ar-concentration in the NF{sub 3}/Ar mixture gas. The roughness factor (R{sub a}) values were decreased from 51.5 nm to 25.5 nm for the As-cut SiC, from 0.25 nm to 0.20 nm for the Epi-SiC, from 5.0 nm to 0.7 nm for the Si-face mirror-polished SiC, and from 0.20 nm to 0.16 nm for the C-face mirror-polished SiC by adding 60% Ar to the NF{sub 3} gas. Both the R{sub a} values of the Epi- and the C-face mirror-polished wafer surfaces etched using the NF{sub 3}/Ar (40:60) plasma were similar to that treated with mirror polishing, so-called the Catalyst-Referred Etching (CARE) method, with which the lowest roughness of surface was obtained among the chemical mirror polishing methods. Etching duration for smoothing the single-crystalline SiC surface using its treatment was one third of that with the CARE method.

  11. Hohlraum fill gas density scaling of x-ray drive, symmetry, and laser coupling backscatter in 6.72-mm NIF hohlraums

    NASA Astrophysics Data System (ADS)

    Jones, Ogden; Izumi, N.; Hopkins, L. B.; Strozzi, D. J.; Amendt, P. A.; Hall, G. N.; Ho, D. D.; Khan, S. F.; Meezan, N. B.; Moody, J. D.; Nagel, S. R.; Ralph, J. E.; Town, R. P. J.

    2014-10-01

    Most ignition experiments carried out on the NIF to date have used hohlraums with helium gas fill at 1--1.6 mg/cc density in order to prevent excessive hohlraum wall motion and help to control drive symmetry. A unique feature of 2-shock high density carbon (HDC) ignition designs is that they require a much shorter (~7 ns) laser pulse than the ~20 ns duration pulses that are typically used for 3-shock or 4-shock CH ablator designs, so there is less time for the wall to move. As a result, it is possible to reduce the hohlraum gas fill density. We have done 2D convergent ablator experiments in a 6.72 mm diameter hohlraum at fill densities of 0.03 and 0.6 mg/cc. These experiments used HDC capsules driven by a 1.5 MJ, 370 TW peak power laser pulse. They demonstrated low backscatter (<4%) and effective drives that are much closer to high flux model predictions than for typical gas-filled hohlraums. The 0.6 mg/cc fill reduced the amount of unabsorbed inner cone power that is reflected out of the hohlraum for the 0.03 mg/cc case. Also, the 0.6 mg/cc has improved symmetry that is in good agreement with modeling. Prepared by LLNL under Contract DE-AC52-07NA27344.

  12. Corrosion behavior of Fe-20Cr and Ni-20Cr alloys in Ar-H[sub 2]O-HBr gas mixtures at 1000 K

    SciTech Connect

    Oenay, B.; Saito, Yasutoshi )

    1993-08-01

    Discontinuous mass-change measurements and corrosion-product analyses were made for Fe-20Cr and Ni-20Cr alloys after exposing them to Ar-H[sub 2]O-HBr gas mixtures at 1000 K for 24 hours. Predominantly chromia scales formed on both alloys. Upon cooling, the scales remained adherent to the Fe-20Cr alloy but spalled extensively from Ni-20Cr samples. After tests in HBr-rich gas mixtures, bromine-rich corrosion products were found underneath chromia scales on both alloys while nickel evaporation was observed from Ni-20Cr samples. Preoxidation of the Ni-20Cr alloy prior to exposure to Ar-H[sub 2]O-HBr gas mixtures increased chromia scale adherence but did not prevent nickel loss from the alloy. Chromia scales formed on the Fe-20Cr alloy were more protective due to the absence of iron oxides in the scale. Large NiO crystals formed over the Ni-20Cr alloy decreased chromia-scale adherence and increased nickel loss from the alloy due to the low stability of NiO in HBr-containing gas mixtures. 20 refs., 8 figs., 5 tabs.

  13. Computational modelling of the interaction of shock waves with multiple gas-filled bubbles in a liquid

    NASA Astrophysics Data System (ADS)

    Betney, M. R.; Tully, B.; Hawker, N. A.; Ventikos, Y.

    2015-03-01

    This study presents a computational investigation of the interactions of a single shock wave with multiple gas-filled bubbles in a liquid medium. This work illustrates how multiple bubbles may be used in shock-bubble interactions to intensify the process on a local level. A high resolution front-tracking approach is used, which enables explicit tracking of the gas-liquid interface. The collapse of two identical bubbles, one placed behind the other is investigated in detail, demonstrating that peak pressures in a two bubble arrangement can exceed those seen in single bubble collapse. Additionally, a parametric investigation into the effect of bubble separation is presented. It is found that the separation distance has a significant effect on both the shape and velocity of the main transverse jet of the second bubble. Extending this analysis to effects of relative bubble size, we show that if the first bubble is sufficiently small relative to the second, it may become entirely entrained in the second bubble main transverse jet. In contrast, if the first bubble is substantially larger than the second, it may offer it significant protection from the incident shock. This protection is utilised in the study of a triangular array of three bubbles, with the central bubble being significantly smaller than the outer bubbles. It is demonstrated that, through shielding of bubbles until later in the collapse process, pressures over five times higher than the maximum pressure observed in the single bubble case may be achieved. This corresponds to a peak pressure that is approximately 40 times more intense than the incident shock wave. This work has applications in a number of different fields, including cavitation erosion, explosives, targeted drug delivery/intensification, and shock wave lithotripsy.

  14. Primordial abundance of 40Ar

    NASA Astrophysics Data System (ADS)

    Sripada, V. S. Murty

    Primordial abundance of the isotope (40) Ar is still not known accurately. Recent results from Genesis could also not provide (40) Ar/ (36) Ar value of solar wind, due mainly to the overwhelming (40) Ar blank. A major part of (40) Ar is contributed by the radioactive decay of (40) K (half life = 1.25 Ga), even in the nebula, as the nebula grew old. Any attempt to determine this quantity needs a sample that satisfies the following criteria: A primitive mineral/phase that formed very early in the nebula, that can trap a large amount of noble gas (Ar); and a phase that acquires minimum amount (or total absence) of in situ produced components (cosmogenic and radiogenic) of Ar. Carbon phases in the ureilite meteorites and Phase Q from chondrites best fit this criteria. The minimum (40) Ar/ (36) Ar value so far observed in Phase Q is 0.2. Also, the relatively lower value of 1.035±±0.002 for trapped (129) Xe/ (132) Xe in ureilites, as compared to 1.042±±0.002 in Phase Q suggests that trapping of gases in ureilites might have predated that of Phase Q. If this interpretation is valid, ureilites are a better host of most primitive nebular Ar. Earlier attempts on ureilite studies in 1970s have yielded the lowest (40) Ar/ (36) Ar ratio in the meteorite Dayalpur, the major uncertainty for this value mostly coming from blank correction for (40) Ar/ (36) Ar. Recent developments in low blank extraction systems and more sensitive multi-collector noble gas mass spectrometers, as compared to 1970s have prompted us to make a fresh attempt in measuring this important quantity. We have analysed a number of ureilite acid residues by stepwise temperature extraction, using both pyrolysis and combustion techniques, for Ar to ascertain the trapped (40) Ar/ (36) Ar ratio in the solar nebula. These acid residues are mostly made of C rich phases, with only trace amounts of K (radiogenic parent of (40) Ar) and target elements for the production of cosmogenic Ar component. They mostly contain

  15. Angle-resolved photoemission spectroscopy with 9-eV photon-energy pulses generated in a gas-filled hollow-core photonic crystal fiber

    SciTech Connect

    Bromberger, H. Liu, H.; Chávez-Cervantes, M.; Gierz, I.; Ermolov, A.; Belli, F.; Abdolvand, A.; Russell, P. St. J.; Travers, J. C.; Calegari, F.; Li, M. T.; Lin, C. T.; Cavalleri, A.

    2015-08-31

    A recently developed source of ultraviolet radiation, based on optical soliton propagation in a gas-filled hollow-core photonic crystal fiber, is applied here to angle-resolved photoemission spectroscopy (ARPES). Near-infrared femtosecond pulses of only few μJ energy generate vacuum ultraviolet radiation between 5.5 and 9 eV inside the gas-filled fiber. These pulses are used to measure the band structure of the topological insulator Bi{sub 2}Se{sub 3} with a signal to noise ratio comparable to that obtained with high order harmonics from a gas jet. The two-order-of-magnitude gain in efficiency promises time-resolved ARPES measurements at repetition rates of hundreds of kHz or even MHz, with photon energies that cover the first Brillouin zone of most materials.

  16. Action mechanism of hydrogen gas on deposition of HfC coating using HfCl4-CH4-H2-Ar system

    NASA Astrophysics Data System (ADS)

    Wang, Yalei; Li, Zehao; Xiong, Xiang; Li, Xiaobin; Chen, Zhaoke; Sun, Wei

    2016-12-01

    Hafnium carbide coatings were deposited on carbon/carbon composites by low pressure chemical vapor deposition using HfCl4-CH4-H2-Ar system. The microstructure, mechanical and ablation resistance performance of HfC coatings deposited with various H2 concentrations were investigated. The effect of hydrogen gas on the deposition of HfC coating was also discussed. Results show that all of the deposited coatings are composed of single cubic HfC phase, the hydrogen gas acted as a crucial role in determining the preferred orientation, microstructure and growth behavior of HfC coatings. During the deposition process, the gas phase supersaturation of the reaction species can be controlled by adjusting the hydrogen gas concentration. When deposited with low hydrogen gas concentration, the coating growth was dominated by the nucleation of HfC, which results in the particle-stacked structure of HfC coating. Otherwise, the coating growth was dominated by the crystal growth at high hydrogen gas concentration, which leads to the column-arranged structure of HfC coating. Under the ablation environment, the coating C2 exhibits better configurational stability and ablation resistance. The coating structure has a significant influence on the mechanical and ablation resistance properties of HfC coating.

  17. Experiments on seismic behavior of back-fill gravel layer as liquefaction countermeasure of buried gas pipelines

    SciTech Connect

    Takada, Shiro; Ogawa, Yasuo; Shimizu, Kenji; Ueno, Junichi

    1995-12-31

    Experiments on seismic behavior of back-fill gravel layer as a back-fill material for buried pipelines was experimented with to investigate the effectiveness against liquefaction with a scaled model using a shaking table. A non-liquefied sandy surface layer was made with a steel mold divided into several pieces for a model. The back-fill gravel was found to be efficient for drainage but didn`t prevent liquefaction from occurring in the below layer. It was also found that the pipe doesn`t move up by buoyancy but subsides following the settlement of the back-fill gravel.

  18. Pore- and fracture-filling gas hydrate reservoirs in the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II Green Canyon 955 H well

    USGS Publications Warehouse

    Lee, M.W.; Collett, T.S.

    2012-01-01

    High-quality logging-while-drilling (LWD) downhole logs were acquired in seven wells drilled during the Gulf of MexicoGasHydrateJointIndustryProjectLegII in the spring of 2009. Well logs obtained in one of the wells, the GreenCanyon Block 955Hwell (GC955-H), indicate that a 27.4-m thick zone at the depth of 428 m below sea floor (mbsf; 1404 feet below sea floor (fbsf)) contains gashydrate within sand with average gashydrate saturations estimated at 60% from the compressional-wave (P-wave) velocity and 65% (locally more than 80%) from resistivity logs if the gashydrate is assumed to be uniformly distributed in this mostly sand-rich section. Similar analysis, however, of log data from a shallow clay-rich interval between 183 and 366 mbsf (600 and 1200 fbsf) yielded average gashydrate saturations of about 20% from the resistivity log (locally 50-60%) and negligible amounts of gashydrate from the P-wave velocity logs. Differences in saturations estimated between resistivity and P-wave velocities within the upper clay-rich interval are caused by the nature of the gashydrate occurrences. In the case of the shallow clay-rich interval, gashydrate fills vertical (or high angle) fractures in rather than fillingpore space in sands. In this study, isotropic and anisotropic resistivity and velocity models are used to analyze the occurrence of gashydrate within both the clay-rich and sand dominated gas-hydrate-bearing reservoirs in the GC955-Hwell.

  19. Comparison of conventional K-Ar and 40Ar/39Ar dating of young mafic volcanic rocks

    USGS Publications Warehouse

    Lanphere, M.A.

    2000-01-01

    K-Ar and 40Ar/39Ar ages have been measured on nine mafic volcanic rocks younger than 1 myr from the Snake River Plain (Idaho), Mount Adams (Washington), and Crater Lake (Oregon). The K-Ar ages were calculated from Ar measurements made by isotope dilution and K2O measurements by flame photometry. The 40Ar/39Ar ages are incremental-heating experiments using a low-blank resistance-heated furnace. The results indicate that high-quality ages can be measured on young, mafic volcanic rocks using either the K-Ar or the 40Ar/39Ar technique. The precision of an 40Ar/39Ar plateau age generally is better than the precision of a K-Ar age because the plateau age is calculated by pooling the ages of several gas increments. The precision of a plateau age generally is better than the precision of an isotope correlation (isochron) age for the same sample. For one sample the intercept of the isochron yielded an 40Ar/36Ar value significantly different from the atmospheric value of 295.5. Recalculation of increment ages using the isochron intercept for the composition of nonradiogenic Ar in the sample resulted in much better agreement of ages for this sample. The results of this study also indicate that, given suitable material and modern equipment, precise K-Ar and 40Ar/39Ar ages can be measured on volcanic rocks as young as the latest Pleistocene, and perhaps even the Holocene.

  20. The size and structure of the laser entrance hole in gas-filled hohlraums at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Schneider, M. B.; MacLaren, S. A.; Widmann, K.; Meezan, N. B.; Hammer, J. H.; Yoxall, B. E.; Bell, P. M.; Benedetti, L. R.; Bradley, D. K.; Callahan, D. A.; Dewald, E. L.; Döppner, T.; Eder, D. C.; Edwards, M. J.; Guymer, T. M.; Hinkel, D. E.; Hohenberger, M.; Hsing, W. W.; Kervin, M. L.; Kilkenny, J. D.; Landen, O. L.; Lindl, J. D.; May, M. J.; Michel, P.; Milovich, J. L.; Moody, J. D.; Moore, A. S.; Ralph, J. E.; Regan, S. P.; Thomas, C. A.; Wan, A. S.

    2015-12-01

    At the National Ignition Facility, a thermal X-ray drive is created by laser energy from 192 beams heating the inside walls of a gold cylinder called a "hohlraum." The x-ray drive heats and implodes a fuel capsule. The laser beams enter the hohlraum via laser entrance holes (LEHs) at each end. The LEH radius decreases as heated plasma from the LEH material blows radially inward but this is largely balanced by hot plasma from the high-intensity region in the center of the LEH pushing radially outward. The x-ray drive on the capsule is deduced by measuring the time evolution and spectra of the x-radiation coming out of the LEH and correcting for geometry and for the radius of the LEH. Previously, the LEH radius was measured using time-integrated images in an x-ray band of 3-5 keV (outside the thermal x-ray region). For gas-filled hohlraums, the measurements showed that the LEH radius is larger than that predicted by the standard High Flux radiation-hydrodynamic model by about 10%. A new platform using a truncated hohlraum ("ViewFactor hohlraum") is described, which allows time-resolved measurements of the LEH radius at thermal x-ray energies from two views, from outside the hohlraum and from inside the hohlraum. These measurements show that the LEH radius closes during the low power part of the pulse but opens up again at peak power. The LEH radius at peak power is larger than that predicted by the models by about 15%-20% and does not change very much with time. In addition, time-resolved images in a >4 keV (non-thermal) x-ray band show a ring of hot, optically thin gold plasma just inside the optically thick LEH plasma. The structure of this plasma varies with time and with Cross Beam Energy Transfer.

  1. Density of atoms in Ar*(3p{sup 5}4s) states and gas temperatures in an argon surfatron plasma measured by tunable laser spectroscopy

    SciTech Connect

    Huebner, S.; Carbone, E. A. D.; Mullen, J. J. A. M. van der; Sadeghi, N.

    2013-04-14

    This study presents the absolute argon 1 s (in Paschens's notation) densities and the gas temperature, T{sub g}, obtained in a surfatron plasma in the pressure range 0.65gas pressures of p<10 mbar, changes to a Voigt shape at p>10 mbar, for which the pressure broadening can no more be neglected. T{sub g} is in the range of 480-750 K, increasing with pressure and decreasing with the distance from the microwave launcher. Taking into account the line of sight effects of the absorption measurements, a good agreement is found with our previous measurements by Rayleigh scattering of T{sub g} at the tube center. In the studied pressure range, the Ar(4 s) atom densities are in the order of 10{sup 16}-10{sup 18} m{sup -3}, increasing towards the end of the plasma column, decreasing with the pressure. In the low pressure side, a broad minimum is found around 10Ar(4 s) atom densities increase slightly with rising pressure. For the studied pressure range and all axial positions, the density ratio: 1s{sub 5}/1s{sub 4}/1s{sub 3} is very close to a Boltzmann equilibrium by electron impact mixing at the local T{sub e}, which was previously measured by Thomson scattering. The Ar(4 s) densities are successfully compared to a detailed Collisional Radiative Model.

  2. Density of atoms in Ar*(3p54s) states and gas temperatures in an argon surfatron plasma measured by tunable laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Hübner, S.; Sadeghi, N.; Carbone, E. A. D.; van der Mullen, J. J. A. M.

    2013-04-01

    This study presents the absolute argon 1 s (in Paschens's notation) densities and the gas temperature, Tg, obtained in a surfatron plasma in the pressure range 0.65

    gas pressures of p <10 mbar, changes to a Voigt shape at p >10 mbar, for which the pressure broadening can no more be neglected. Tg is in the range of 480-750 K, increasing with pressure and decreasing with the distance from the microwave launcher. Taking into account the line of sight effects of the absorption measurements, a good agreement is found with our previous measurements by Rayleigh scattering of Tg at the tube center. In the studied pressure range, the Ar(4 s) atom densities are in the order of 1016-1018 m-3, increasing towards the end of the plasma column, decreasing with the pressure. In the low pressure side, a broad minimum is found around 10

    Ar(4 s) atom densities increase slightly with rising pressure. For the studied pressure range and all axial positions, the density ratio: 1s5/1s4/1s3 is very close to a Boltzmann equilibrium by electron impact mixing at the local Te, which was previously measured by Thomson scattering. The Ar(4 s) densities are successfully compared to a detailed Collisional Radiative Model.

  3. Investigations on Ni-Co-Mn-Sn thin films: Effect of substrate temperature and Ar gas pressure on the martensitic transformations and exchange bias properties

    SciTech Connect

    Machavarapu, Ramudu Jakob, Gerhard

    2015-03-15

    We report the effect of substrate temperature (T{sub S}) and Ar gas pressure (P{sub D}) on the martensitic transformations, magnetic and exchange bias (EB) properties in Heusler type Ni-Co-Mn-Sn epitaxial thin films. Martensitic transformation temperatures and EB fields at 5 K were found to increase with increasing T{sub S}. The observed maximum EB value of 320 Oe after field cooling in the film deposited at 650 {sup ∘}C is high among the values reported for Ni-Mn-Sn thin films which is attributed to the coexistence of ferromagnetic (FM) and antiferromagnetic (AF) phases in the martensitic state. In the case of P{sub D} variation, with increase in P{sub D}, martensitic transformation temperatures were increased and a sharp transformation was observed in the film deposited at 0.06 mbar. Magnetization values at 5 K were higher for increasing P{sub D}. These observations are attributed to the compositional shift. EB effect is also present in these films. Microstructural features observed using atomic force microscopy (AFM) shows a fine twinning and reduced precipitation with increase in P{sub D}, which is also confirmed from the scanning electron microscopy (SEM) images. EB effects in both series were confirmed from the training effect. Target ageing effect has been observed in the films deposited before and after ninety days of time interval. This has been confirmed both on substrate temperature and Ar gas pressure variations.

  4. Multistage plasma initiation process by pulsed CO2 laser irradiation of a Ti sample in an ambient gas (He, Ar, or N2)

    NASA Astrophysics Data System (ADS)

    Hermann, J.; Boulmer-Leborgne, C.; Mihailescu, I. N.; Dubreuil, B.

    1993-02-01

    New experimental results are reported on plasma initiation in front of a titanium sample irradiated by ir (λ=10.6 μm) laser pulses in an ambient gas (He, Ar, and N2) at pressures ranging from several Torr up to the atmosphere. The plasma is studied by space- and time-resolved emission spectroscopy, while sample vaporization is probed by laser-induced fluorescence spectroscopy. Threshold laser intensities leading to the formation of a plasma in the vapor and in the ambient gases are determined. Experimental results support the model of a vaporization mechanism for the plasma initiation (vaporization-initiated plasma breakdown). The plasma initiation is described by simple numerical criteria based on a two-stage process. Theoretical predictions are found to be in a reasonable agreement with the experiment. This study provides also a clear explanation of the influence of the ambient gas on the laser beam-metal surface energy transfer. Laser irradiation always causes an important vaporization when performed in He, while in the case of Ar or N2, the interaction is reduced in heating and vaporization of some surface defects and impurities.

  5. Effect of N{sub 2} and Ar gas on DC arc plasma generation and film composition from Ti-Al compound cathodes

    SciTech Connect

    Zhirkov, Igor Rosen, Johanna; Oks, Efim

    2015-06-07

    DC arc plasma from Ti, Al, and Ti{sub 1−x}Al{sub x} (x = 0.16, 0.25, 0.50, and 0.70) compound cathodes has been characterized with respect to plasma chemistry (charged particles) and charge-state-resolved ion energy for Ar and N{sub 2} pressures in the range 10{sup −6} to 3 × 10{sup −2} Torr. Scanning electron microscopy was used for exploring the correlation between the cathode and film composition, which in turn was correlated with the plasma properties. In an Ar atmosphere, the plasma ion composition showed a reduction of Al of approximately 5 at. % compared to the cathode composition, while deposited films were in accordance with the cathode stoichiometry. Introducing N{sub 2} above ∼5 × 10{sup −3} Torr, lead to a reduced Al content in the plasma as well as in the film, and hence a 1:1 correlation between the cathode and film composition cannot be expected in a reactive environment. This may be explained by an influence of the reactive gas on the arc mode and type of erosion of Ti and Al rich contaminations, as well as on the plasma transport. Throughout the investigated pressure range, a higher deposition rate was obtained from cathodes with higher Al content. The origin of generated gas ions was investigated through the velocity rule, stating that the most likely ion velocities of all cathode elements from a compound cathode are equal. The results suggest that the major part of the gas ions in Ar is generated from electron impact ionization, while gas ions in a N{sub 2} atmosphere primarily originate from a nitrogen contaminated layer on the cathode surface. The presented results provide a contribution to the understanding processes of plasma generation from compound cathodes. It also allows for a more reasonable approach to the selection of composite cathode and experimental conditions for thin film depositions.

  6. Ordering and growth of rare gas films (Xe, Kr, Ar, and Ne) on the pseudo-ten-fold quasicrystalline approximant Al₁₃Co₄(100) surface.

    PubMed

    Petucci, J; Karimi, M; Huang, Y-T; Curtarolo, S; Diehl, R D

    2014-03-05

    Adsorption of the rare gases Kr, Ar, and Ne on the complex alloy surface Al₁₃Co₄(100) was studied using grand canonical Monte Carlo (GCMC) computer simulations. This surface is an approximant to the ten-fold decagonal Al-Ni-Co quasicrystalline surface, on which rare gas adsorption was studied previously. Comparison of adsorption results on the periodic Al₁₃Co₄(100) surface with those of the quasiperiodic Al-Ni-Co surface indicates some similarities, such as layer-by-layer growth, and some dissimilarities, such as the formation of Archimedes tiling phases (Mikhael et al 2008 Nature 454 501, Shechtman et al 1984 Phys. Rev. Lett. 53 1951, Macia 2006 Rep. Prog. Phys. 69 397, Schmiedeberg et al 2010 Eur. Phys. J. E 32 25-34, Kromer et al 2012 Phys. Rev. Lett. 108 218301, Schmiedeberg and Stark 2008 Phys. Rev. Lett. 101 218302). The conditions under which Archimedes tiling phases (ATP) emerge on Al₁₃Co₄(100) are examined and their presence is related to the gas-gas and gas-surface interaction parameters.

  7. Water-window microscopy using compact, laser-plasma source based on Ar/He double stream gas-puff target

    NASA Astrophysics Data System (ADS)

    Wachulak, Przemyslaw W.; Skorupka, Marcin; Bartnik, Andrzej; Kostecki, Jerzy; Jarocki, Roman; Szczurek, Mirosław; Wegrzynski, Lukasz; Fok, Tomasz; Fiedorowicz, Henryk

    2013-05-01

    Photon-based (bosonic-type) imaging at short wavelength vs. electron, or recently neutron, imaging has additional advantages due to different interaction of photons with matter and thus high resolution photon-based imaging is still of high interest to the scientific community. In this work we try to combine the advantages of employing compact, laboratory type laser-plasma short wavelength source, based on Ar/He gas puff target, emitting incoherent radiation, with the "water-window" spectral range. This unique combination is highly suitable for biological imaging, and allows developing a small size microscopy setup, which might be used in various fields of science and technology. Thus, in this paper we report on recent advances in "water-window" desk-top microscopy setup employing a laser-plasma SXR source based on a double stream gas puff target and Wolter type-I objective. The system allows capturing magnified images of the objects with ~1 μm spatial resolution up to ~40 μm thickness and single SXR pulse exposure time as low as 3 ns. For the SXR microscope Ar plasma was produced by focusing of the pumping laser pulses, from Nd:YAG laser (Eksma), by a lens onto a gas puff target. EUV radiation from the plasma was collected and focused by an ellipsoidal, axi-symmetrical nickel coated condenser mirror, developed by Rigaku, Inc. The condenser is a broad-band optic, capable of efficiently reflecting radiation from the EUV range down to SXR region with energy cut-off of ~800 eV. To spectrally narrow the emission from argon plasma a free-standing titanium filter (Lebow) was used. Spectrally filtered radiation illuminates the sample. Then the sample was imaged onto a SXR sensitive back-illuminated, CCD camera (Andor) by a Wolter type-I reflective objective. A characterization and optimization of both the source and the microscope setups are presented and discussed.

  8. The size and structure of the laser entrance hole in gas-filled hohlraums at the National Ignition Facility

    SciTech Connect

    Schneider, M. B. MacLaren, S. A.; Widmann, K.; Meezan, N. B.; Hammer, J. H.; Yoxall, B. E.; Bell, P. M.; Benedetti, L. R.; Bradley, D. K.; Callahan, D. A.; Dewald, E. L.; Döppner, T.; Eder, D. C.; Edwards, M. J.; Hinkel, D. E.; Hsing, W. W.; Kervin, M. L.; Landen, O. L.; Lindl, J. D.; May, M. J.; and others

    2015-12-15

    At the National Ignition Facility, a thermal X-ray drive is created by laser energy from 192 beams heating the inside walls of a gold cylinder called a “hohlraum.” The x-ray drive heats and implodes a fuel capsule. The laser beams enter the hohlraum via laser entrance holes (LEHs) at each end. The LEH radius decreases as heated plasma from the LEH material blows radially inward but this is largely balanced by hot plasma from the high-intensity region in the center of the LEH pushing radially outward. The x-ray drive on the capsule is deduced by measuring the time evolution and spectra of the x-radiation coming out of the LEH and correcting for geometry and for the radius of the LEH. Previously, the LEH radius was measured using time-integrated images in an x-ray band of 3–5 keV (outside the thermal x-ray region). For gas-filled hohlraums, the measurements showed that the LEH radius is larger than that predicted by the standard High Flux radiation-hydrodynamic model by about 10%. A new platform using a truncated hohlraum (“ViewFactor hohlraum”) is described, which allows time-resolved measurements of the LEH radius at thermal x-ray energies from two views, from outside the hohlraum and from inside the hohlraum. These measurements show that the LEH radius closes during the low power part of the pulse but opens up again at peak power. The LEH radius at peak power is larger than that predicted by the models by about 15%–20% and does not change very much with time. In addition, time-resolved images in a >4 keV (non-thermal) x-ray band show a ring of hot, optically thin gold plasma just inside the optically thick LEH plasma. The structure of this plasma varies with time and with Cross Beam Energy Transfer.

  9. New Empirical Potential Energy Functions for the Heavier Homonuclear Rare Gas Pairs: {Ne}_2, {Ar}_2, {Kr}_2, and {Xe}_2

    NASA Astrophysics Data System (ADS)

    Myatt, Philip Thomas; Baker, Matthew T.; Kang, Ju-Hee; Escobar Moya, Andres; McCourt, Frederick R. W.; Le Roy, Robert J.

    2016-06-01

    The many decades of work on determining accurate analytic pair potentials for rare gas dimers from experimental data focussed largely on the use of bulk non-ideal gas and collisional properties, with the use of spectroscopic data being somewhat of an afterthought, for testing the resulting functions. This was a natural result of experimental challenges, as the very weak binding of ground-state rare gas pairs made high resolution spectroscopy a relatively late arrival as a practical tool in this area. However, we believe that it is now time for a comprehensive reassessment. Following up on a preliminary report at this meeting five years ago, this paper describes work to determine a new generation of empirical potential energy functions for the four heavier (i.e., not involving He) homonuclear rare gas pairs from direct fits to all available spectroscopic, pressure virial, and acoustic virial coefficient data, with the resulting functions being `tuned' by comparisons with available thermal transport property data: viscosity, mass diffusion and thermal diffusion, and thermal conductivity data, and tested against the best available ab initio potentials. The resulting functions are everywhere smooth and differentiable to all orders, incorporate the correct (damped) theoretical inverse-power long-range behaviour, and have sensible short-range extrapolation behaviour. R.J. Le Roy, C.J.W. Mackie, P. Chandrasekhar and K.M. Sentjens, ``Accurate New Potential Energy Functions From Spectroscopic and Virial Coefficient Data for the Ten Rare Gas Pairs formed from Ne, Ar, Kr and Xe, paper MF03 at the 66th Ohio State University International Symposium on Molecular Spectroscopy, Columbus, Ohio, June 13-17 (2011).

  10. Effect of glow DBD modulation on gas and thin film chemical composition: case of Ar/SiH4/NH3 mixture

    NASA Astrophysics Data System (ADS)

    Vallade, Julien; Bazinette, Remy; Gaudy, Laura; Massines, Françoise

    2014-06-01

    In recent years, atmospheric pressure plasma-enhanced chemical vapour deposition has been identified as a convenient way to deposit good quality thin films. With this type of process, where the gas mixture is injected on one side of the electrodes, the chemical composition of the gas evolves with the gas residence time in the plasma. The consequence is a possible gradient in the chemical composition over the thickness of in-line coatings. The present work shows that the modulation of the plasma with a square signal significantly reduces this gradient while the drawback of low growth rate is avoided by increasing the discharge power. This study deals with plane/plane glow dielectric barrier discharges (DBDs) in an Ar/NH3/SiH4 gas mixture to make thin films. The 50 kHz discharge power of the glow DBD was varied by increasing voltage and modulating excitation. The impact on (i) the plasma development was observed through emission spectroscopy and (ii) the thin film coating through Fourier transform infrared measurements. It is shown that the modulation significantly decreases the time and the energy needed to achieve stable chemistry, enhances secondary chemistry and limits disturbance induced by impurities because of a slower decrease of SiH4 concentration and thus a higher ratio of SiH4/impurities, all very important points for in-line AP-PECVD development. When the growth rate is limited by diffusion, coating growth continues when the discharge is off, so long as there is a precursor gradient between the surface and the gas bulk. A higher discharge power steepens this gradient, which enhances diffusion from the bulk and thus growth rate.

  11. Ternary recombination of H3+, H2D+, HD2+, and D3+ with electrons in He/Ar/H2/D2 gas mixtures

    NASA Astrophysics Data System (ADS)

    Kalosi, Abel; Dohnal, Petr; Plasil, Radek; Johnsen, Rainer; Glosik, Juraj

    2016-09-01

    The temperature dependence of the ternary recombination rate coefficients of H2D+ and HD2+ ions has been studied in the temperature range of 80-150 K at pressures from 500 to 1700 Pa in a stationary afterglow apparatus equipped with a cavity ring-down spectrometer. Neutral gas mixtures consisting of He/Ar/H2/D2 (with typical number densities 1017 /1014 /1014 /1014 cm-3) were employed to produce the desired ionic species and their fractional abundances were monitored as a function of helium pressure and the [D2]/[H2] ratio of the neutral gas. In addition, the translational and the rotational temperature and the ortho to para ratio were monitored for both H2D+ and HD2+ ions. A fairly strong pressure dependence of the effective recombination rate coefficient was observed for both ion species, leading to ternary recombination rate coefficients close to those previously found for (helium assisted) ternary recombination of H3+ and D3+. Work supported by: Czech Science Foundation projects GACR 14-14649P, GACR 15-15077S, GACR P209/12/0233, and by Charles University in Prague Project Nr. GAUK 692214.

  12. Effect of gas properties on the dynamics of the electrical slope asymmetry effect in capacitive plasmas: comparison of Ar, H2 and CF4

    NASA Astrophysics Data System (ADS)

    Bruneau, B.; Lafleur, T.; Gans, T.; O'Connell, D.; Greb, A.; Korolov, I.; Derzsi, A.; Donkó, Z.; Brandt, S.; Schüngel, E.; Schulze, J.; Diomede, P.; Economou, D. J.; Longo, S.; Johnson, E.; Booth, J.-P.

    2016-02-01

    Tailored voltage excitation waveforms provide an efficient control of the ion energy (through the electrical asymmetry effect) in capacitive plasmas by varying the ‘amplitude’ asymmetry of the waveform. In this work, the effect of a ‘slope’ asymmetry of the waveform is investigated by using sawtooth-like waveforms, through which the sheath dynamic can be manipulated. A remarkably different discharge dynamic is found for Ar, H2, and CF4 gases, which is explained by the different dominant electron heating mechanisms and plasma chemistries. In comparison to Argon we find that the electrical asymmetry can even be reversed by using an electronegative gas such as CF4. Phase resolved optical emission spectroscopy measurements, probing the spatiotemporal distribution of the excitation rate show excellent agreement with the results of particle-in-cell simulations, confirming the high degree of correlation between the excitation rates with the dominant heating mechanisms in the various gases. It is shown that, depending on the gas used, sawtooth-like voltage waveforms may cause a strong asymmetry.

  13. Simulations of Ar gas-puff Z-pinch radiation sources with double shells and central jets on the Z generator

    NASA Astrophysics Data System (ADS)

    Tangri, V.; Harvey-Thompson, A. J.; Giuliani, J. L.; Thornhill, J. W.; Velikovich, A. L.; Apruzese, J. P.; Ouart, N. D.; Dasgupta, A.; Jones, B.; Jennings, C. A.

    2016-10-01

    Radiation-magnetohydrodynamic simulations using the non-local thermodynamic equilibrium Mach2-Tabular Collisional-Radiative Equilibrium code in (r, z) geometry are performed for two pairs of recent Ar gas-puff Z-pinch experiments on the refurbished Z generator with an 8 cm diameter nozzle. One pair of shots had an outer-to-inner shell mass ratio of 1:1.6 and a second pair had a ratio of 1:1. In each pair, one of the shots had a central jet. The experimental trends in the Ar K-shell yield and power are reproduced in the calculations. However, the K-shell yield and power are significantly lower than the other three shots for the case of a double-shell puff of 1:1 mass ratio and no central jet configuration. Further simulations of a hypothetical experiment with the same relative density profile of this configuration, but higher total mass, show that the coupled energy from the generator and the K-shell yield can be increased to levels achieved in the other three configurations, but not the K-shell power. Based on various measures of effective plasma radius, the compression in the 1:1 mass ratio and no central jet case is found to be less because the plasma inside the magnetic piston is hotter and of lower density. Because of the reduced density, and the reduced radiation cooling (which is proportional to the square of the density), the core plasma is hotter. Consequently, for the 1:1 outer-to-inner shell mass ratio, the load mass controls the yield and the center jet controls the power.

  14. Characterization of pure and mixed Ar, Kr and Xe gas jets generated by different nozzles and a study of X-ray radiation yields after interaction with a sub-ps laser pulse

    NASA Astrophysics Data System (ADS)

    Schultz, K. A.; Kantsyrev, V. L.; Safronova, A. S.; Moschella, J. J.; Wiewior, P.; Shlyaptseva, V. V.; Weller, M. E.; Petkov, E. E.; Shrestha, I. K.; Stafford, A.; Cooper, M. C.

    2016-10-01

    Gas jets accelerated through a linear supersonic and a conical nozzle, comprising a monomer/cluster mix, were characterized at UNR using a Mach-Zehnder type interferometer and Rayleigh scattering. A comparison of the two nozzle types is presented, showing that the linear nozzle produces gas jets of an order of magnitude denser than the conical nozzle. The linear gas jets of Ar, Kr, and Xe as well as triple mixtures with different percentages of each of the aforementioned gases were characterized. The densest gas jets used Ar as the target gas, while the least dense jets came from Kr. Cluster radii of the pure gases were measured, and Xe gas jets were found to produce the largest gas clusters. A study of X-ray generation by gas jet-laser plasma was performed at the UNR Leopard laser (1.057 μm, 350 fs, ˜1019 W/cm2) on the linear nozzle. The gas jets were irradiated with a high-intensity sub-ps laser pulse. An absolute X-ray output of the laser-gas jet interactions measured by the calibrated PCDs is presented and show that triple mixtures of Xe, Kr, and Ar each exhibited a higher X-ray yield compared to the pure gases. A strong anisotropy of X-ray radiation with respect to laser beam polarization direction is observed in all the gas jets. In fact, this anisotropy is different in three spectral regions (>1.4, 3.5 and 9 keV).

  15. Design options for improved performance with high-density carbon ablators and low-gas fill hohlraum targets

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, L.; Divol, L.; Lepape, S.; Meezan, N. B.; Dewald, E.; Ho, D.; Khan, S.; Pak, A.; Ralph, J.; Ross, J. S.

    2016-10-01

    Recent simulation-based and experimental work using high-density carbon ablators in unlined uranium hohlraums with 0.3 mg/cc helium fill have demonstrated round implosions with minimal evolution of Legendre moment P2 during burn. To extend this promising work, design studies have been performed to explore potential performance improvements with larger capsules, while maintaining similar case-to-capsule target ratios. We present here the results of these design studies, which will motivate a series of upcoming experiments at the National Ignition Facility. Prepared by LLNL under Contract DE-AC52-07NA27344.

  16. Purification and Detection of 39Ar in Groundwater Samples via Low-Level Counting

    NASA Astrophysics Data System (ADS)

    Mace, E. K.; Aalseth, C.; Brandenberger, J. M.; Humble, P.; Panisko, M.; Seifert, A.; Williams, R. M.

    2015-12-01

    Argon-39 can be used as a radiotracer to age-date groundwater aquifers to study recharge rates and to better understand the mean residence time, or age distributions, of groundwater. Argon-39 (with a half-life of 269 years) is created in the atmosphere by cosmic rays interacting with argon in the air (primarily 40Ar). The use of 39Ar as a radiotracer fills a gap in the age dating range which is currently covered by 3H/3He or 85Kr (< 50 years) and 14C (>1000 years); 39Ar fills the intermediate time scale range from 50-1000 years where the previously established radiotracers are not adequate. We will introduce the process for purifying and detecting 39Ar in ground water using ultra-low-background proportional counters (ULBPCs) at the shallow underground laboratory at Pacific Northwest National Laboratory. Argon-39 is detected through direct beta counting using ULBPCs loaded with a mixture of geologic argon (extracted from a carbon dioxide well with no measureable 39Ar activity) and methane, which enhances the sensitivity for 39Ar measurements. The ULBPCs have been shown to have a background count rate of 148 counts per day (cpd) in the energy range 3-400 keV when filled with 10 atm of P-10 counting gas (90% geologic Ar, 10% CH4). Initial demonstration samples were collected from groundwater aquifers in Fresno, California supported by the United States Geological Survey (USGS). A discussion of the sampling technique to degas the water from these wells and to then purify it for counting will be presented. In order to quantify the 39Ar contribution in the groundwater samples, the ULBPCs were characterized to determine two components: 1) the detector efficiency to modern levels of 39Ar, and 2) the remaining detector background (using geologic sourced argon which is free from 39Ar - no measureable 39Ar activity). These characterization results will be presented along with a discussion of the quantification of the 39Ar age of the demonstration measurements.

  17. Influence of Ar/O2/H2O Feed Gas and N2/O2/H2O Environment on the Interaction of Time Modulated MHz Atmospheric Pressure Plasma Jet (APPJ) with Model Polymers

    NASA Astrophysics Data System (ADS)

    Oehrlein, Gottlieb; Luan, Pingshan; Knoll, Andrew; Kondeti, Santosh; Bruggeman, Peter

    2016-09-01

    An Ar/O2/H2O fed time modulated MHz atmospheric pressure plasma jet (APPJ) in a sealed chamber was used to study plasma interaction with model polymers (polystyrene, poly-methyl methacrylate, etc.). The amount of H2O in the feed gas and/or present in the N2, O2, or N2/O2 environment was controlled. Short lived species such as O atoms and OH radicals play a crucial role in polymer etching and surface modifications (obtained from X-ray photoelectron spectroscopy of treated polymers without additional atmospheric exposure). Polymer etching depth for Ar/air fed APPJ mirrors the decay of gas phase O atoms with distance from the APPJ nozzle in air and is consistent with the estimated O atom flux at the polymer surface. Furthermore, whereas separate O2 or H2O admixture to Ar enhances polymer etching, simultaneous addition of O2 and H2O to Ar quenches polymer etching. This can be explained by the mutual quenching of O with OH, H and HO2 in the gas phase. Results where O2 and/or H2O in the environment were varied are consistent with these mechanisms. All results will be compared with measured and simulated species densities reported in the literature. We gratefully acknowledge funding from US Department of Energy (DE-SC0001939) and National Science Foundation (PHY-1415353).

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

    SciTech Connect

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

    2015-12-15

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

  19. Theoretical prediction of the linear isomers for rare gas-carbon disulfide complexes: He-CS₂, Ne-CS₂, and Ar-CS₂.

    PubMed

    Zang, Limin; Dai, Wei; Zheng, Limin; Duan, Chuanxi; Lu, Yunpeng; Yang, Minghui

    2014-03-21

    Theoretical studies of the potential energy surfaces (PESs) and bound states are performed for rare gas-carbon disulfide complexes, He-CS2, Ne-CS2, and Ar-CS2. Three two-dimensional intermolecular PESs are constructed from ab initio data points which are calculated at the CCSD(T) level with aug-cc-pVTZ basis set supplemented with bond functions. We find that the three PESs have very similar features and each PES can be characterized by a global T-shaped minimum, two equivalent local linear minima, and the saddle points between them. The T-shaped isomer is energetically more stable than the linear isomer for each complex. The linear isomers, which have not been observed in experiment so far, are predicted from our PESs and further identified by bound state calculations. Moreover, we assign several intermolecular vibrational states for both the T-shaped and linear isomers of the three complexes via the analysis of wavefunctions. The corresponding vibrational frequencies are calculated from the bound state energies for these assigned states. These frequencies could be helpful for further experimental studies, especially for the linear isomers. We also calculate the rovibrational transition frequencies for the three T-shaped isomers and the pure rotational transition frequencies for the linear isomers, respectively. The accuracy of the PESs is validated by the good agreement between theoretical and experimental results for the rovibrational transition frequencies and spectroscopic parameters.

  20. Mechanism and computational model for Lyman-{alpha}-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

    SciTech Connect

    Louchev, Oleg A.; Saito, Norihito; Wada, Satoshi; Bakule, Pavel; Yokoyama, Koji; Ishida, Katsuhiko; Iwasaki, Masahiko

    2011-09-15

    We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-{alpha} (Ly-{alpha}) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-{alpha} generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-{alpha} radiation generation can achieve a value of {approx}5x10{sup -4} which is restricted by the total combined absorption of the fundamental and generated radiation.

  1. Mechanism and computational model for Lyman-α-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

    NASA Astrophysics Data System (ADS)

    Louchev, Oleg A.; Bakule, Pavel; Saito, Norihito; Wada, Satoshi; Yokoyama, Koji; Ishida, Katsuhiko; Iwasaki, Masahiko

    2011-09-01

    We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-α (Ly-α) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-α generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-α radiation generation can achieve a value of ˜5×10-4 which is restricted by the total combined absorption of the fundamental and generated radiation.

  2. Computer program of data reduction procedures for facilities using CO2-N2-O2-Ar equilibrium real-gas mixtures

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III

    1972-01-01

    Data reduction procedures for determining free-stream and post-normal-shock flow conditions are presented. These procedures are applicable to flows of CO2, N2, O2, Ar, or mixtures of these gases and include the effects of dissociation and ionization. The assumption of thermochemical equilibrium free-stream and post-normal-shock flow is made. Although derived primarily to meet the immediate needs of an expansion tube of a hot gas radiation research facility, these procedures are applicable to any supersonic or hypersonic test facility using these gases or mixtures thereof. The data reduction procedures are based on combinations of three of the following flow parameters measured in the immediate vicinity of the test section: (1) stagnation pressure behind normal shock, (2) free-stream static pressure, (3) stagnation-point heat-transfer rate, (4) free-stream velocity, and (5) free-stream density. Thus, these procedures do not depend explicitly upon measured or calculated upstream flow parameters. The procedures are incorporated into a single computer program written in FORTRAN IV language. A listing of this computer program is presented, along with a description of the inputs required and a sample of the data printout.

  3. 40Ar/39Ar Studies of Antarctic Micrometeorites

    NASA Astrophysics Data System (ADS)

    Saxton, J. M.; Knott, S. F.; Turner, G.; Maurette, M.

    1992-07-01

    We have used the ^40Ar/^39Ar technique to study eight dust particles, in the size range 50-100 microns, collected by filtering Antarctic blue ice (Maurette et al. 1989). The particles were pressed into aluminium foil and their compositions estimated using SEM/EDX techniques. Six were found to have approximately chondritic Mg/Fe/Si ratios, suggesting an extraterrestrial origin. The remaining two particles appeared to be composed mostly of iron and we are not sure of their origin. The particles were then irradiated with a fast neutron fluence of approximately 6 x 10^18 cm^-2, and the argon in them extracted using a pulsed laser delivering about 100 mJ per pulse. We attempted to step heat most of the particles by initially defocusing the beam to reduce the heating effect. In four cases, a sufficient amount of gas was released for step heating to be profitable. The results for five of the chondritic particles are shown in the figure. One yielded a very small amount of gas and is not plotted. The high temperature step is shown for those particles that were step heated. In this diagram, air plots on the y-axis (^36Ar/^40Ar = 0.00338), a purely radiogenic component plots on the x-axis, and addition of ^36Ar moves a point vertically upwards. Four particles have ^36Ar/^40Ar ratios higher than air. This confirms their extraterrestrial origin. We believe the 36Ar is most probably derived from solar energetic particles; only 10^2-10^3 years exposure at 1 AU would be required to produce the level of ^36Ar we observe (10^-12-10^-13 ccSTP), assuming that no 36Ar is lost during atmospheric passage. This is comfortably less than the time taken for a particle of this size to drift in from 2AU to 1AU due to the Poynting Robertson effect, which is of the order 10^5 years. The concentration ^36Ar content is of the order of 10^-7-10^-6 g^-1, which is comparable to the levels of trapped ^36Ar found in primitive meteorites. This interpretation of the source of the ^36Ar would seem to

  4. Enhanced high harmonic generation driven by high-intensity laser in argon gas-filled hollow core waveguide.

    PubMed

    Cassou, Kevin; Daboussi, Sameh; Hort, Ondrej; Guilbaud, Olivier; Descamps, Dominique; Petit, Stéphane; Mével, Eric; Constant, Eric; Kazamias, Sophie

    2014-07-01

    We show that a significant enhancement of the photon flux produced by high harmonic generation can be obtained through guided configuration at high laser intensity largely above the saturation intensity. We identify two regimes. At low pressure, we observe an intense second plateau in the high harmonic spectrum in argon. At relatively high pressure, complex interplay between strongly time-dependent ionization processes and propagation effects leads to important spectral broadening without loss of spectral brightness. We show that the relevant parameter for this physical process is the product of laser peak power by gas pressure. We compare source performances with high harmonic generation using a gas jet in loose focusing geometry and conclude that the source developed is a good candidate for injection devices such as seeded soft x-ray lasers or free electron lasers in the soft x-ray range.

  5. Nonlinear compression of picosecond chirped pulse from thin-disk amplifier system through a gas-filled hollow-core fiber

    NASA Astrophysics Data System (ADS)

    Lu, Jun; Huang, Zhi-Yuan; Wang, Ding; Xu, Yi; Liu, Yan-Qi; Guo, Xiao-Yang; Li, Wen-Kai; Wu, Fen-Xiang; Liu, Zheng-Zheng; Leng, Yu-Xin

    2016-12-01

    We theoretically study the nonlinear compression of a 20-mJ, 1030-nm picosecond chirped pulse from the thin-disk amplifier in a krypton gas-filled hollow-core fiber. The chirp from the thin-disk amplifier system has little influence on the initial pulse, however, it shows an effect on the nonlinear compression in hollow-core fiber. We use a large diameter hollow waveguide to restrict undesirable nonlinear effects such as ionization; on the other hand, we employ suitable gas pressure and fiber length to promise enough spectral broadening; with 600-μm, 6-bar (1 bar = 105 Pa), 1.8-m hollow fiber, we obtain 31.5-fs pulse. Moreover, we calculate and discuss the optimal fiber lengths and gas pressures with different initial durations induced by different grating compression angles for reaching a given bandwidth. These results are meaningful for a compression scheme from picoseconds to femtoseconds. Project supported by the National Basic Research Program of China (Grant No. 2011CB808101), the Funds from the Chinese Academy of Sciences, and the National Natural Science Foundation of China (Grant Nos. 1112790, 10734080, 61221064, 60908008, and 61078037).

  6. Performance of a gas flow ionization detector filled with He-iso-C4H10 mixtures for STIM-T

    NASA Astrophysics Data System (ADS)

    Marques, A. C.; Fraga, M. M. F. R.; Fonte, P.; Beasley, D. G.; Cruz, C.; Alves, L. C.; da Silva, R. C.

    2015-04-01

    A cylindrical gas flow ionization chamber has been developed for measuring particle energy in Scanning Transmission Ion Microscopy Tomography (STIM-T) experiments due to its ability to withstand the direct beam. The response of a He-iso-C4H10 filled ionization detector to 2 MeV H+ and He+ beams was studied. Different operating parameters, such as concentration of isobutane (in the range of 55-100%), anode voltage, amplifier shaping time, the geometry of the detector entrance canal and the solid angle of the detector, were investigated. The stable operating plateau and the anode voltage at which the best energy resolution is attained were also determined for every gas mixture. The best energy resolution achieved so far for 2 MeV H+ and He+ static beams was ∼1.3%, which is comparable to that of Si PIN diode detectors (in the range of 15-30 keV). Computed tomography (CT) was applied to a set of STIM projections acquired with the gas ionization chamber at the IST/CTN microprobe beam line in order to visualize the 3D-mass distribution in a test structure.

  7. ³⁹Ar/Ar measurements using ultra-low background proportional counters.

    PubMed

    Hall, Jeter; Aalseth, Craig E; Bonicalzi, Ricco M; Brandenberger, Jill M; Day, Anthony R; Humble, Paul H; Mace, Emily K; Panisko, Mark E; Seifert, Allen

    2016-01-01

    Age-dating groundwater and seawater using the (39)Ar/Ar ratio is an important tool to understand water mass-flow rates and mean residence time. Low-background proportional counters developed at Pacific Northwest National Laboratory use mixtures of argon and methane as counting gas. We demonstrate sensitivity to (39)Ar by comparing geological (ancient) argon recovered from a carbon dioxide gas well and commercial argon. The demonstrated sensitivity to the (39)Ar/Ar ratio is sufficient to date water masses as old as 1000 years.

  8. Simulation of electron beam formation and transport in a gas-filled electron-optical system with a plasma emitter

    NASA Astrophysics Data System (ADS)

    Grishkov, A. A.; Kornilov, S. Yu.; Rempe, N. G.; Shidlovskiy, S. V.; Shklyaev, V. A.

    2016-07-01

    The results of computer simulations of the electron-optical system of an electron gun with a plasma emitter are presented. The simulations are performed using the KOBRA3-INP, XOOPIC, and ANSYS codes. The results describe the electron beam formation and transport. The electron trajectories are analyzed. The mechanisms of gas influence on the energy inhomogeneity of the beam and its current in the regions of beam primary formation, acceleration, and transport are described. Recommendations for optimizing the electron-optical system with a plasma emitter are presented.

  9. The generation and evolution of anisotropic gas-permeability during viscous deformation in conduit-filling ignimbrites

    NASA Astrophysics Data System (ADS)

    Kolzenburg, Stephan; Russell, Kelly

    2015-04-01

    Gas-permeability plays a governing role in the pre-explosive pressurization of volcanic edifices. Pressurization may only occur once the total volume flux of gases emitted by an underlying magmatic or hydrothermal source exceeds the flow capacity of the permeable pathways present in the edifice. We have measured the physical properties (strain, porosity, permeability and ultrasonic wave velocities) of breadcrust bombs recovered from the deposits of the 2350 B.P. eruption of Mt Meager, BC, Canada. These rocks represent a conduit-infilling pyroclastic breccia that underwent various degrees of welding and deformation and present a remarkable opportunity to constrain the nature and timescale of mechanical processes operating within explosive volcanic conduits during repose periods between eruptive cycles. Here we present data from permeability measurements along the directions of maximum and minimum shortening which help quantifying the effect of vesicle microstructure on permeability. Permeability is measured by applying a range of confining pressures (between 3.4 and 17.2 MPa) to each sample and imposing a constant head (of 0.2 to 3.5 MPa) across the sample. The permeability is then determined using a modified version of Darcy's law applicable to compressible fluids. These rocks display a profound directionality in the measured physical properties resulting from the deformation-induced fabric. For all samples the permeability across the elongation fabric is highly correlated to the sample porosity whereas along the elongation fabric there is little effect of porosity on permeability. At porosity values of about 20% the permeability seems to reach a minimum at 10-16 m2 and does not change significantly with further reduction of porosity. Further, the effect of confining pressure on the permeability of these samples appears to be more pronounced across the elongation fabric than along the elongation fabric. The deformation fabric has a significant effect on the gas

  10. Residual gas analysis (RGA) and shear strength characteristics of a silver-filled epoxy and polyimide under long-term, high-temperature storage conditions. Final report

    SciTech Connect

    Adams, B.E.

    1994-04-01

    Introduction of organic materials into hermetically sealed electronic packages increases the risk of failure due to contamination. The contaminants of concern are moisture and ionics. This combination can lead to unwanted electrical pathways and/or corrosion. To minimize sealed-in moisture, packages are vacuum-baked for 16 hours at 200 C and Au/Sn solder-sealed i a glove box purged with dry nitrogen. Even following this procedure, the package plating and organic adhesive can still outgas moisture during high-temperature storage. Long-term aging characteristics for a silver-filled epoxy and a silver-filled polyimide were investigated. Leadless chip carriers (LCCs) containing die attached with epoxy or polyimide were aged at 25 C, 100 C, 150 C, and 200 C for up to six months. Residual gas analysis (RGA) and die shear testing were performed on each package. Results indicate that the epoxy can withstand storage at 150 C with no increase in internal moisture. The polyimide could only be stored at 100 C. No loss in shear strength for epoxy or polyimide was noted at any storage condition.

  11. Dramatic Raman Gain Suppression in the Vicinity of the Zero Dispersion Point in a Gas-Filled Hollow-Core Photonic Crystal Fiber

    NASA Astrophysics Data System (ADS)

    Bauerschmidt, S. T.; Novoa, D.; Russell, P. St. J.

    2015-12-01

    In 1964 Bloembergen and Shen predicted that Raman gain could be suppressed if the rates of phonon creation and annihilation (by inelastic scattering) exactly balance. This is only possible if the momentum required for each process is identical, i.e., phonon coherence waves created by pump-to-Stokes scattering are identical to those annihilated in pump-to-anti-Stokes scattering. In bulk gas cells, this can only be achieved over limited interaction lengths at an oblique angle to the pump axis. Here we report a simple system that provides dramatic Raman gain suppression over long collinear path lengths in hydrogen. It consists of a gas-filled hollow-core photonic crystal fiber whose zero dispersion point is pressure adjusted to lie close to the pump laser wavelength. At a certain precise pressure, stimulated generation of Stokes light in the fundamental mode is completely suppressed, allowing other much weaker phenomena such as spontaneous Raman scattering to be explored at high pump powers.

  12. Understanding the dynamics of photoionization-induced nonlinear effects and solitons in gas-filled hollow-core photonic crystal fibers

    SciTech Connect

    Saleh, Mohammed F.; Biancalana, Fabio

    2011-12-15

    We present the details of our previously formulated model [Saleh et al., Phys. Rev. Lett. 107, 203902 (2011)] that governs pulse propagation in hollow-core photonic crystal fibers filled by an ionizable gas. By using perturbative methods, we find that the photoionization process induces the opposite phenomenon of the well-known Raman self-frequency redshift of solitons in solid-core glass fibers, as was recently experimentally demonstrated [Hoelzer et al., Phys. Rev. Lett. 107, 203901 (2011)]. This process is only limited by ionization losses, and leads to a constant acceleration of solitons in the time domain with a continuous blueshift in the frequency domain. By applying the Gagnon-Belanger gauge transformation, multipeak ''inverted gravitylike'' solitary waves are predicted. We also demonstrate that the pulse dynamics shows the ejection of solitons during propagation in such fibers, analogous to what happens in conventional solid-core fibers. Moreover, unconventional long-range nonlocal interactions between temporally distant solitons, unique of gas plasma systems, are predicted and studied. Finally, the effects of higher-order dispersion coefficients and the shock operator on the pulse dynamics are investigated, showing that the conversion efficiency of resonant radiation into the deep UV can be improved via plasma formation.

  13. Optimal generation of spatially coherent soft X-ray isolated attosecond pulses in a gas-filled waveguide using two-color synthesized laser pulses

    PubMed Central

    Jin, Cheng; Hong, Kyung-Han; Lin, C. D.

    2016-01-01

    We numerically demonstrate the generation of intense, low-divergence soft X-ray isolated attosecond pulses in a gas-filled hollow waveguide using synthesized few-cycle two-color laser waveforms. The waveform is a superposition of a fundamental and its second harmonic optimized such that highest harmonic yields are emitted from each atom. We then optimize the gas pressure and the length and radius of the waveguide such that bright coherent high-order harmonics with angular divergence smaller than 1 mrad are generated, for photon energy from the extreme ultraviolet to soft X-rays. By selecting a proper spectral range enhanced isolated attosecond pulses are generated. We study how dynamic phase matching caused by the interplay among waveguide mode, neutral atomic dispersion, and plasma effect is achieved at the optimal macroscopic conditions, by performing time-frequency analysis and by analyzing the evolution of the driving laser’s electric field during the propagation. Our results, when combined with the on-going push of high-repetition-rate lasers (sub- to few MHz’s) may eventually lead to the generation of high-flux, low-divergence soft X-ray tabletop isolated attosecond pulses for applications. PMID:27929036

  14. Direct comparative study on the energy level alignments in unoccupied/occupied states of organic semiconductor/electrode interface by constructing in-situ photoemission spectroscopy and Ar gas cluster ion beam sputtering integrated analysis system

    SciTech Connect

    Yun, Dong-Jin Chung, JaeGwan; Kim, Yongsu; Park, Sung-Hoon; Kim, Seong-Heon; Heo, Sung

    2014-10-21

    Through the installation of electron gun and photon detector, an in-situ photoemission and damage-free sputtering integrated analysis system is completely constructed. Therefore, this system enables to accurately characterize the energy level alignments including unoccupied/occupied molecular orbital (LUMO/HOMO) levels at interface region of organic semiconductor/electrode according to depth position. Based on Ultraviolet Photoemission Spectroscopy (UPS), Inverse Photoemission Spectroscopy (IPES), and reflective electron energy loss spectroscopy, the occupied/unoccupied state of in-situ deposited Tris[4-(carbazol-9-yl)phenyl]amine (TCTA) organic semiconductors on Au (E{sub LUMO}: 2.51 eV and E{sub HOMO}: 1.35 eV) and Ti (E{sub LUMO}: 2.19 eV and E{sub HOMO}: 1.69 eV) electrodes are investigated, and the variation of energy level alignments according to work function of electrode (Au: 4.81 eV and Ti: 4.19 eV) is clearly verified. Subsequently, under the same analysis condition, the unoccupied/occupied states at bulk region of TCTA/Au structures are characterized using different Ar gas cluster ion beam (Ar GCIB) and Ar ion sputtering processes, respectively. While the Ar ion sputtering process critically distorts both occupied and unoccupied states in UPS/IPES spectra, the Ar GCIB sputtering process does not give rise to damage on them. Therefore, we clearly confirm that the in-situ photoemission spectroscopy in combination with Ar GCIB sputtering allows of investigating accurate energy level alignments at bulk/interface region as well as surface region of organic semiconductor/electrode structure.

  15. Development of an intelligent system for cooling rate and fill control in GMAW. [Gas Metal Arc Welding (GMAW)

    SciTech Connect

    Einerson, C.J.; Smartt, H.B.; Johnson, J.A.; Taylor, P.L. ); Moore, K.L. )

    1992-01-01

    A control strategy for gas metal arc welding (GMAW) is developed in which the welding system detects certain existing conditions and adjusts the process in accordance to pre-specified rules. This strategy is used to control the reinforcement and weld bead centerline cooling rate during welding. Relationships between heat and mass transfer rates to the base metal and the required electrode speed and welding speed for specific open circuit voltages are taught to a artificial neural network. Control rules are programmed into a fuzzy logic system. TRADITOINAL CONTROL OF THE GMAW PROCESS is based on the use of explicit welding procedures detailing allowable parameter ranges on a pass by pass basis for a given weld. The present work is an exploration of a completely different approach to welding control. In this work the objectives are to produce welds having desired weld bead reinforcements while maintaining the weld bead centerline cooling rate at preselected values. The need for this specific control is related to fabrication requirements for specific types of pressure vessels. The control strategy involves measuring weld joint transverse cross-sectional area ahead of the welding torch and the weld bead centerline cooling rate behind the weld pool, both by means of video (2), calculating the required process parameters necessary to obtain the needed heat and mass transfer rates (in appropriate dimensions) by means of an artificial neural network, and controlling the heat transfer rate by means of a fuzzy logic controller (3). The result is a welding machine that senses the welding conditions and responds to those conditions on the basis of logical rules, as opposed to producing a weld based on a specific procedure.

  16. 39Ar/Ar measurements using ultra-low background proportional counters

    SciTech Connect

    Hall, Jeter C.; Aalseth, Craig E.; Bonicalzi, Ricco; Brandenberger, Jill M.; Day, Anthony R.; Humble, Paul H.; Mace, Emily K.; Panisko, Mark E.; Seifert, Allen

    2016-01-08

    Age dating groundwater and seawater using 39Ar/Ar ratios is an important tool to understand water mass flow rates and mean residence time. For modern or contemporary argon, the 39Ar activity is 1.8 mBq per liter of argon. Radiation measurements at these activity levels require ultra low-background detectors. Low-background proportional counters have been developed at Pacific Northwest National Laboratory. These detectors use traditional mixtures of argon and methane as counting gas, and the residual 39Ar from commercial argon has become a predominant source of background activity in these detectors. We demonstrated sensitivity to 39Ar by using geological or ancient argon from gas wells in place of commercial argon. The low level counting performance of these proportional counters is then demonstrated for sensitivities to 39Ar/Ar ratios sufficient to date water masses as old as 1000 years.

  17. Ar-Ar_Redux: rigorous error propagation of 40Ar/39Ar data, including covariances

    NASA Astrophysics Data System (ADS)

    Vermeesch, P.

    2015-12-01

    Rigorous data reduction and error propagation algorithms are needed to realise Earthtime's objective to improve the interlaboratory accuracy of 40Ar/39Ar dating to better than 1% and thereby facilitate the comparison and combination of the K-Ar and U-Pb chronometers. Ar-Ar_Redux is a new data reduction protocol and software program for 40Ar/39Ar geochronology which takes into account two previously underappreciated aspects of the method: 1. 40Ar/39Ar measurements are compositional dataIn its simplest form, the 40Ar/39Ar age equation can be written as: t = log(1+J [40Ar/39Ar-298.5636Ar/39Ar])/λ = log(1 + JR)/λ Where λ is the 40K decay constant and J is the irradiation parameter. The age t does not depend on the absolute abundances of the three argon isotopes but only on their relative ratios. Thus, the 36Ar, 39Ar and 40Ar abundances can be normalised to unity and plotted on a ternary diagram or 'simplex'. Argon isotopic data are therefore subject to the peculiar mathematics of 'compositional data', sensu Aitchison (1986, The Statistical Analysis of Compositional Data, Chapman & Hall). 2. Correlated errors are pervasive throughout the 40Ar/39Ar methodCurrent data reduction protocols for 40Ar/39Ar geochronology propagate the age uncertainty as follows: σ2(t) = [J2 σ2(R) + R2 σ2(J)] / [λ2 (1 + R J)], which implies zero covariance between R and J. In reality, however, significant error correlations are found in every step of the 40Ar/39Ar data acquisition and processing, in both single and multi collector instruments, during blank, interference and decay corrections, age calculation etc. Ar-Ar_Redux revisits every aspect of the 40Ar/39Ar method by casting the raw mass spectrometer data into a contingency table of logratios, which automatically keeps track of all covariances in a compositional context. Application of the method to real data reveals strong correlations (r2 of up to 0.9) between age measurements within a single irradiation batch. Propertly taking

  18. The improvement of mechanical properties of aluminum nitride and alumina by 1 keV Ar{sup +} ion irradiation in reactive gas environment

    SciTech Connect

    Koh, S.K.; Son, Y.B.; Gam, J.S.; Kim, C.J.; Choi, W.K.; Jung, H.J.

    1996-12-31

    Ar ions with 1 keV energy was irradiated on aluminum nitride in an O{sub 2} environment to increase the bonding strength with Cu and also on alumina in an N{sub 2} environment to increase the bending strength. Cu(1,000 {angstrom}) films were deposited by ion-beam sputter on Ar{sup +} irradiated/unirradiated AlN surfaces and the change of the bond strength was investigated by a scratch test. For the study of chemical structural change don the Ar{sup +} irradiated AlN surface. Cu(50{angstrom}) were deposited on an AlN substrate and XPS depth profile analysis was performed. Cu films deposited on Ar{sup +} irradiated AlN under an O{sub 2} environment showed the bond strength of 30 Newton by a scratch test. On the basis of Cu3p, Al2p near core levels and O1s, N1s core level spectra, it was found that the improvement of bond strength of Cu films on the AlN surface resulted from the formation of intermediate layers such as copper oxide and aluminum oxynitride. The bending strength of polycrystalline alumina irradiated by Ar ions in an N{sub 2} environment was also increased.

  19. XPS Depth Profile Analysis of Zn3N2 Thin Films Grown at Different N2/Ar Gas Flow Rates by RF Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Haider, M. Baseer

    2017-01-01

    Zinc nitride thin films were grown on fused silica substrates at 300 °C by radio frequency magnetron sputtering. Films were grown at different N2/Ar flow rate ratios of 0.20, 0.40, 0.60, 0.80, and 1.0. All the samples have grain-like surface morphology with an average surface roughness ranging from 4 to 5 nm and an average grain size ranging from 13 to16 nm. Zn3N2 samples grown at lower N2/Ar ratio are polycrystalline with secondary phases of ZnO present, whereas at higher N2/Ar ratio, no ZnO phases were found. Highly aligned films were achieved at N2/Ar ratio of 0.60. Hall effect measurements reveal that films are n-type semiconductors, and the highest carrier concentration and Hall mobility was achieved for the films grown at N2/Ar ratio of 0.60. X-ray photoelectron study was performed to confirm the formation of Zn-N bonds and to study the presence of different species in the film. Depth profile XPS analyses of the films reveal that there is less nitrogen in the bulk of the film compared to the nitrogen on the surface of the film whereas more oxygen is present in the bulk of the films possibly occupying the nitrogen vacancies.

  20. XPS Depth Profile Analysis of Zn3N2 Thin Films Grown at Different N2/Ar Gas Flow Rates by RF Magnetron Sputtering.

    PubMed

    Haider, M Baseer

    2017-12-01

    Zinc nitride thin films were grown on fused silica substrates at 300 °C by radio frequency magnetron sputtering. Films were grown at different N2/Ar flow rate ratios of 0.20, 0.40, 0.60, 0.80, and 1.0. All the samples have grain-like surface morphology with an average surface roughness ranging from 4 to 5 nm and an average grain size ranging from 13 to16 nm. Zn3N2 samples grown at lower N2/Ar ratio are polycrystalline with secondary phases of ZnO present, whereas at higher N2/Ar ratio, no ZnO phases were found. Highly aligned films were achieved at N2/Ar ratio of 0.60. Hall effect measurements reveal that films are n-type semiconductors, and the highest carrier concentration and Hall mobility was achieved for the films grown at N2/Ar ratio of 0.60. X-ray photoelectron study was performed to confirm the formation of Zn-N bonds and to study the presence of different species in the film. Depth profile XPS analyses of the films reveal that there is less nitrogen in the bulk of the film compared to the nitrogen on the surface of the film whereas more oxygen is present in the bulk of the films possibly occupying the nitrogen vacancies.

  1. Spatial distribution of Ar-40/Ar-39 ages in lunar breccia 14301.

    NASA Technical Reports Server (NTRS)

    Megrue, G. H.

    1973-01-01

    The distribution of stable and radioactive argon isotopes in a lunar breccia has been measured in situ by laser probe mass spectrometry. This new technique determines the spatial distribution of Ar-40/Ar-39 ages on less than .1 milligram of material. Calculated Ar-40/Ar-39 ages of clasts within this breccia are 3.7 and 2.9 b.y. Parentless radiogenic Ar-40 exists within the fine-grained matrix and appears to have been trapped simultaneously with solar argon. This 'atmosphere' of ambient gas appears to have been incorporated into the rock by an impact event not more than 3 b.y. ago.

  2. Metrologically-Calibrated 40Ar Concentrations and Ages of Mineral Standards Used in 40Ar/39Ar Geochronology

    NASA Astrophysics Data System (ADS)

    Morgan, L. E.; Davidheiser-Kroll, B.; Kuiper, K.; Wijbrans, J. R.; Mark, D. F.

    2015-12-01

    In geochronology, isotopic ages are determined from the ratio of parent and daughter nuclide concentrations in minerals. For dating of geological material using the K-Ar system, the simultaneous determination of 40Ar and 40K concentrations on the same aliquot is not possible. Therefore, a widely used variant, the 40Ar/39Ar technique, involves the production of 39Ar from 39K by neutron bombardment and the reliance on indirect natural calibrators of the neutron flux, referred to as "mineral standards." Many mineral standards still in use rely on decades-old determinations of 40Ar concentrations; resulting uncertainties, both systematic and analytical, impede the determination of higher accuracy ages using the K-Ar decay system. We present results for the 40Ar concentrations and ages of mineral standards determined based on a modern gas delivery system (Morgan et al. 2011), which delivers metrologically-traceable amounts of 40Ar and thus allows for the sensitivity calibration of noble gas mass spectrometers.

  3. Diameter control of gold nanoparticles synthesized in gas phase using atmospheric-pressure H2/Ar plasma jet and gold wire as the nanoparticle source: Control by varying the H2/Ar mixture ratio

    NASA Astrophysics Data System (ADS)

    Shimizu, Yoshiki

    2017-01-01

    This report describes diameter control of gold nanoparticles (AuNPs) during synthesis using an atmospheric-pressure H2/Ar plasma jet drive with pulse-modulated ultrahigh frequency, employing Au wire as the NP source material. During this process, where most of the AuNPs are regarded as formed through condensation from Au vapor derived by the Au wire etching, the mean diameter varied in the approximate range of 2-12 nm with H2 volume ratios up to 3.9%. In plasma diagnostics, results showed that the H2 volume ratio influences the plasma discharge behaviour, which affects the heat flux density flowed into the Au wire, and the atomic hydrogen concentration in the plasma. Both seemed to influence the etching rate of the Au wire per unit area, which is directly related to the concentration of Au vapor in the plasma. The concentration is one factor affecting the particle size evolution because of the collisions among vapor species in reaction field. Therefore, the AuNP size variation with the H2 volume ratio was discussed from the perspective of the etching rate of the Au wire at each H2 volume ratio.

  4. 40Ar/39Ar systematics and argon diffusion in amber: implications for ancient earth atmospheres

    USGS Publications Warehouse

    Landis, G.P.; Snee, L.W.

    1991-01-01

    Argon isotope data indicate retained argon in bulk amber (matrix gas) is radiogenic [40Ar/39Ar ???32o] than the much more abundant surface absorbed argon [40Ar/39Ar ???295.5]. Neutron-induced 39Ar is retained in amber during heating experiments to 150?? -250??C, with no evidence of recoiled 39Ar found after irradiation. A maximum permissible volume diffusion coefficient of argon in amber (at ambient temperature) D???1.5 x 10-17 cm2S-1 is calculated from 39Ar retention. 40Ar/39Ar age calculations indicate Dominican Republic amber is ??? 45 Ma and North Dakota amber is ??? 89 Ma, both at least reasonable ages for the amber based upon stratigraphic and paleontological constraints and upon the small amount of radiogenic 40Ar. To date, over 300 gas analyses of ambers and resins of Cretaceous to Recent age that are geographically distributed among fifteen noted world locations identify mixtures of gases in different sites within amber (Berner and Landis, 1988). The presence of multiple mixing trends between compositionally distinct end-members gases within the same sample and evidence for retained radiogenic argon within the amber argue persuasivley against rapid exchange by diffusion of amber-contained gases with moder air. Only gas in primary bubbles entrapped between successive flows of tree resin has been interpreted as original "ancient air", which is an O2-rich end-member gas with air-like N2/Ar ratios. Gas analyses of these primary bubbles indicate atmospheric O2 levels in the Late Cretaceous of ??? 35%, and that atmospheric O2 dropped by early Tertiary time to near a present atmospheric level of 21% O2. A very low argon diffusion coefficient in amber persuasively argues for a gas in primary bubbles trapped in amber being ancient air (possibly modified only by O2 reaction with amber). ?? 1991.

  5. Re-Evaluation of Ar-39 - Ar-40 Ages for Apollo Lunar Rocks 15415 and 60015

    NASA Technical Reports Server (NTRS)

    Park, J.; Nyquist, L. E.; Bogard, D. D.; Garrison, D. H.; Shih, C.-Y.

    2010-01-01

    We re-analyzed 39Ar-40Ar ages of Apollo lunar highland samples 15415 and 60015, two ferroan anorthosites analyzed previously in the 1970 s, with a more detailed approach and with revised decay constants. From these samples we carefully prepared 100-200 mesh mineral separates for analysis at the Noble Gas Laboratory at NASA-Johnson Space Center. The Ar-39-Ar-40 age spectra for 15415 yielded an age of 3851 +/- 38 Ma with 33-99% of Ar39 release, roughly in agreement with previously reported Ar-Ar ages. For 60015, we obtained an age of 3584 +/- 152 Ma in 23-98% of Ar39 release, also in agreement with previously reported Ar-Ar ages of approximately 3.5 Ga. Highland anorthosites like these are believed by many to be the original crust of the moon, formed by plagioclase floatation atop a magma ocean, however the Ar-Ar ages of 15415 and 60015 are considerably younger than lunar crust formation. By contrast, recently recovered lunar anorthosites such as Dhofar 489, Dhofar 908, and Yamato 86032 yield older Ar-Ar ages, up to 4.35 Ga, much closer to time of formation of the lunar crust. It follows that the Ar-Ar ages of the Apollo samples must have been reset by secondary heating, and that this heating affected highland anorthosites at both the Apollo 15 and Apollo 16 landing sites but did not affect lunar highland meteorites. One obvious consideration is that while the Apollo samples were collected from the near side of the moon, these lunar meteorites are thought to have originated from the lunar far side

  6. First-principles calibration of 40Ar/39Ar mineral standards and complete extraction of 40Ar* from sanidine

    NASA Astrophysics Data System (ADS)

    Morgan, L. E.; Kuiper, K.; Mark, D.; Postma, O.; Villa, I. M.; Wijbrans, J. R.

    2010-12-01

    40Ar/39Ar geochronology relies on comparing argon isotopic data for unknowns to those for knowns. Mineral standards used as neutron fluence monitors must be dated by the K-Ar method (or at least referenced to a mineral of known K-Ar age). The commonly used age of 28.02 ± 0.28 Ma for the Fish Canyon sanidine (FCs) (Renne et al., 1998) is based upon measurements of radiogenic 40Ar in GA1550 biotite (McDougall and Roksandic, 1974), but underlying full data were not published (these measurements were never intended for use as an international standard), so uncertainties are difficult to assess. Recent developments by Kuiper et al. (2008) and Renne et al. (2010) are limited by their reliance on the accuracy of other systems. Modern technology should allow for more precise and accurate calibration of primary K-Ar and 40Ar/39Ar standards. From the ideal gas law, the number of moles of 40Ar in a system can be calculated from measurements of pressure, volume, and temperature. Thus we have designed and are proceeding to build a pipette system to introduce well-determined amounts of 40Ar into noble gas extraction lines and mass spectrometers. This system relies on components with calibrations traceable to SI unit prototypes, including a diaphragm pressure gauge (MKS Instruments), thermocouples, and a “slug” of an accurately determined volume to be inserted into the reservoir for volume determinations of the reservoir and pipette. The system will be renewable, with a lifetime of ca. 1 month for gas in the reservoir, and portable, to permit interlaboratory calibrations. The quantitative extraction of 40Ar* from the mineral standard is of highest importance; for sanidine standards this is complicated by high melt viscosity during heating. Experiments adding basaltic “zero age glass” (ZAG) to decrease melt viscosity are underway. This has previously been explored by McDowell (1983) with a resistance furnace, but has not been quantitatively addressed with laser heating

  7. ArArCALC—software for 40Ar/ 39Ar age calculations

    NASA Astrophysics Data System (ADS)

    Koppers, Anthony A. P.

    2002-06-01

    ArArCALC is a Microsoft Excel ® 97-2000-XP application for performing calculations in 40Ar/ 39Ar geochronology. It is coded in Visual Basic for Applications and can be used under the Windows ® 95/98/NT/2000/ME/XP operating systems. ArArCALC provides an easy-to-use graphical interface for the calculation of age plateaus, total fusion ages and isochrons following the regression of 40Ar/ 39Ar mass spectrometry data. Results are stored in single Excel workbooks including nine different data tables and four different diagrams. Analytical, internal and external errors are calculated based on error propagation of all input parameters, analytical data and applied corrections. Finally, the age calculation results can be recalibrated with reference to the primary K-Ar standards (e.g. GA-1550, MMhb-1) in order to obtain more consistent absolute40Ar/ 39Ar age determinations. ArArCALC is distributed as freeware.

  8. Study on the Principle Mechanisms of Heat Transfer for Cryogenic Insulations: Especially Accounting for the Temperature-Dependent Deposition-Evacuation of the Filling Gas (Self-Evacuating Systems)

    NASA Astrophysics Data System (ADS)

    Geisler, Matthias; Vidi, Stephan; Ebert, Hans-Peter

    2016-11-01

    This study concentrates on the principles of heat transfer within cryogenic insulation systems, especially accounting for self-evacuating systems (deposition-evacuation of the filling gas). These principles allow the extrapolation to other temperatures, gases and other materials with the input of only a few experimentally derived or carefully estimated material properties. The type of gas (e.g. air or CO2) within the porous insulation material dominates the behaviour of the effective thermal conductivity during the cooldown of the cryogenic application. This is due to the specific temperature-dependent saturation gas pressure which determines the contribution of the gas conductivity. The selected material classes include powders, fibrous insulations, foams, aerogels and multilayer insulations in the temperature range of 20 K to 300 K. Novel within this study is an analytical function for the total and the mean thermal conductivity with respect to the temperature, type of gas, external pressure and material class of the insulation. Furthermore, the integral mean value of the thermal conductivity, the so-called mean thermal conductivity, is calculated for a mechanically evacuated insulation material and an insulation material evacuated by deposition-evacuation of the filling gas, respectively. This enables a comparison of the total thermal conductivity of cryogenic insulation materials and their applicability for a self-evacuating cryogenic insulation system.

  9. The bond-forming reactions of atomic dications with neutral molecules: formation of ArNH+ and ArN+ from collisions of Ar2+ with NH3.

    PubMed

    Lambert, Natalie; Kearney, Dominic; Kaltsoyannis, Nikolas; Price, Stephen D

    2004-03-24

    An experimental and computational study has been performed to investigate the bond-forming reactivity between Ar(2+) and NH(3). Experimentally, we detect two previously unobserved bond-forming reactions between Ar(2+) and NH(3) forming ArN(+) and ArNH(+). This is the first experimental observation of a triatomic product ion (ArNH(+)) following a chemical reaction of a rare gas dication with a neutral. The intensity of ArNH(+) was found to decrease with increasing collision energy, with a corresponding increase in the intensity of ArN(+), indicating that ArN(+) is formed by the dissociation of ArNH(+). Key features on the potential energy surface for the reaction were calculated quantum chemically using CASSCF and MRCI methods. The calculated reaction mechanism, which takes place on a singlet surface, involves the initial formation of an Ar-N bond to give Ar-NH(3)(2+). This complexation is followed by proton loss via a transition state, and then loss of the two remaining hydrogen atoms in two subsequent activationless steps to give the products (3)ArN(+) + H(+) + 2H. This calculated pathway supports the sequential formation of ArN(+) from ArNH(+), as suggested by the experimental data. The calculations also indicate that no bond-forming pathway exists on the ground triplet surface for this system.

  10. Revised error propagation of 40Ar/39Ar data, including covariances

    NASA Astrophysics Data System (ADS)

    Vermeesch, Pieter

    2015-12-01

    The main advantage of the 40Ar/39Ar method over conventional K-Ar dating is that it does not depend on any absolute abundance or concentration measurements, but only uses the relative ratios between five isotopes of the same element -argon- which can be measured with great precision on a noble gas mass spectrometer. The relative abundances of the argon isotopes are subject to a constant sum constraint, which imposes a covariant structure on the data: the relative amount of any of the five isotopes can always be obtained from that of the other four. Thus, the 40Ar/39Ar method is a classic example of a 'compositional data problem'. In addition to the constant sum constraint, covariances are introduced by a host of other processes, including data acquisition, blank correction, detector calibration, mass fractionation, decay correction, interference correction, atmospheric argon correction, interpolation of the irradiation parameter, and age calculation. The myriad of correlated errors arising during the data reduction are best handled by casting the 40Ar/39Ar data reduction protocol in a matrix form. The completely revised workflow presented in this paper is implemented in a new software platform, Ar-Ar_Redux, which takes raw mass spectrometer data as input and generates accurate 40Ar/39Ar ages and their (co-)variances as output. Ar-Ar_Redux accounts for all sources of analytical uncertainty, including those associated with decay constants and the air ratio. Knowing the covariance matrix of the ages removes the need to consider 'internal' and 'external' uncertainties separately when calculating (weighted) mean ages. Ar-Ar_Redux is built on the same principles as its sibling program in the U-Pb community (U-Pb_Redux), thus improving the intercomparability of the two methods with tangible benefits to the accuracy of the geologic time scale. The program can be downloaded free of charge from

  11. Influence of Xe and Kr impurities on x-ray yield from debris-free plasma x-ray sources with an Ar supersonic gas jet irradiated by femtosecond near-infrared-wavelength laser pulses.

    PubMed

    Kantsyrev, V L; Schultz, K A; Shlyaptseva, V V; Petrov, G M; Safronova, A S; Petkov, E E; Moschella, J J; Shrestha, I; Cline, W; Wiewior, P; Chalyy, O

    2016-11-01

    Many aspects of physical phenomena occurring when an intense laser pulse with subpicosecond duration and an intensity of 10^{18}-10^{19}W/cm^{2} heats an underdense plasma in a supersonic clustered gas jet are studied to determine the relative contribution of thermal and nonthermal processes to soft- and hard-x-ray emission from debris-free plasmas. Experiments were performed at the University of Nevada, Reno (UNR) Leopard laser operated with a 15-J, 350-fs pulse and different pulse contrasts (10^{7} or 10^{5}). The supersonic linear (elongated) nozzle generated Xe cluster-monomer gas jets as well as jets with Kr-Ar or Xe-Kr-Ar mixtures with densities of 10^{18}-10^{19}cm^{-3}. Prior to laser heating experiments, all jets were probed with optical interferometry and Rayleigh scattering to measure jet density and cluster distribution parameters. The supersonic linear jet provides the capability to study the anisotropy of x-ray yield from laser plasma and also laser beam self-focusing in plasma, which leads to efficient x-ray generation. Plasma diagnostics included x-ray diodes, pinhole cameras, and spectrometers. Jet signatures of x-ray emission from pure Xe gas, as well as from a mixture with Ar and Kr, was found to be very different. The most intense x-ray emission in the 1-9 KeV spectral region was observed from gas mixtures rather than pure Xe. Also, this x-ray emission was strongly anisotropic with respect to the direction of laser beam polarization. Non-local thermodynamic equilibrium (Non-LTE) models have been implemented to analyze the x-ray spectra to determine the plasma temperature and election density. Evidence of electron beam generation in the supersonic jet plasma was found. The influence of the subpicosecond laser pulse contrast (a ratio between the laser peak intensity and pedestal pulse intensity) on the jets' x-ray emission characteristics is discussed. Surprisingly, it was found that the x-ray yield was not sensitive to the prepulse contrast ratio.

  12. Influence of Xe and Kr impurities on x-ray yield from debris-free plasma x-ray sources with an Ar supersonic gas jet irradiated by femtosecond near-infrared-wavelength laser pulses

    NASA Astrophysics Data System (ADS)

    Kantsyrev, V. L.; Schultz, K. A.; Shlyaptseva, V. V.; Petrov, G. M.; Safronova, A. S.; Petkov, E. E.; Moschella, J. J.; Shrestha, I.; Cline, W.; Wiewior, P.; Chalyy, O.

    2016-11-01

    Many aspects of physical phenomena occurring when an intense laser pulse with subpicosecond duration and an intensity of 1018-1019W /cm2 heats an underdense plasma in a supersonic clustered gas jet are studied to determine the relative contribution of thermal and nonthermal processes to soft- and hard-x-ray emission from debris-free plasmas. Experiments were performed at the University of Nevada, Reno (UNR) Leopard laser operated with a 15-J, 350-fs pulse and different pulse contrasts (107 or 105). The supersonic linear (elongated) nozzle generated Xe cluster-monomer gas jets as well as jets with Kr-Ar or Xe-Kr-Ar mixtures with densities of 1018-1019cm-3 . Prior to laser heating experiments, all jets were probed with optical interferometry and Rayleigh scattering to measure jet density and cluster distribution parameters. The supersonic linear jet provides the capability to study the anisotropy of x-ray yield from laser plasma and also laser beam self-focusing in plasma, which leads to efficient x-ray generation. Plasma diagnostics included x-ray diodes, pinhole cameras, and spectrometers. Jet signatures of x-ray emission from pure Xe gas, as well as from a mixture with Ar and Kr, was found to be very different. The most intense x-ray emission in the 1-9 KeV spectral region was observed from gas mixtures rather than pure Xe. Also, this x-ray emission was strongly anisotropic with respect to the direction of laser beam polarization. Non-local thermodynamic equilibrium (Non-LTE) models have been implemented to analyze the x-ray spectra to determine the plasma temperature and election density. Evidence of electron beam generation in the supersonic jet plasma was found. The influence of the subpicosecond laser pulse contrast (a ratio between the laser peak intensity and pedestal pulse intensity) on the jets' x-ray emission characteristics is discussed. Surprisingly, it was found that the x-ray yield was not sensitive to the prepulse contrast ratio.

  13. LASER MICROPROBE **4**0Ar/**3**9Ar DATING OF MINERAL GRAINS IN SITU.

    USGS Publications Warehouse

    Sutter, J.F.; Hartung, J.B.

    1984-01-01

    A laser-microprobe attached to a mass spectrometer for **4**0Ar/**3**9Ar age determination of single mineral grains in geological materials has been made operational at the US Geological Survey, Reston, VA. This microanalytical technique involves focusing a pulsed laser beam onto a sample contained in an ultra-high vacuum chamber attached to a rare-gas mass spectrometer. Argon in the neutron-irradiated sample is released by heating with the laser pulse and its isotopic composition is measured to yield an **4**0Ar/**3**9Ar age. Laser probe **4**0Ar/**3**9Ar ages of single mineral grains measured in situ can aid greatly in understanding the chronology of many geological situations where datable minerals are present but are not physically separable in quantities needed for conventional age dating.

  14. Mutual neutralization of atomic rare-gas cations (Ne{sup +}, Ar{sup +}, Kr{sup +}, Xe{sup +}) with atomic halide anions (Cl{sup −}, Br{sup −}, I{sup −})

    SciTech Connect

    Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, Albert A.; Johnsen, Rainer

    2014-01-28

    We report thermal rate coefficients for 12 reactions of rare gas cations (Ne{sup +}, Ar{sup +}, Kr{sup +}, Xe{sup +}) with halide anions (Cl{sup −}, Br{sup −}, I{sup −}), comprising both mutual neutralization (MN) and transfer ionization. No rate coefficients have been previously reported for these reactions; however, the development of the Variable Electron and Neutral Density Attachment Mass Spectrometry technique makes it possible to measure the difference of the rate coefficients for pairs of parallel reactions in a Flowing Afterglow-Langmuir Probe apparatus. Measurements of 18 such combinations of competing reaction pairs yield an over-determined data set from which a consistent set of rate coefficients of the 12 MN reactions can be deduced. Unlike rate coefficients of MN reactions involving at least one polyatomic ion, which vary by at most a factor of ∼3, those of the atom-atom reactions vary by at least a factor 60 depending on the species. It is found that the rate coefficients involving light rare-gas ions are larger than those for the heavier rare-gas ions, but the opposite trend is observed in the progression from Cl{sup −} to I{sup −}. The largest rate coefficient is 6.5 × 10{sup −8} cm{sup 3} s{sup −1} for Ne{sup +} with I{sup −}. Rate coefficients for Ar{sup +}, Kr{sup +}, and Xe{sup +} reacting with Br{sub 2}{sup −} are also reported.

  15. Pulsed submicrosecond multichannel sliding discharges of opposite polarities: Filling of the discharge gap with spark channels

    SciTech Connect

    Trusov, K. K.

    2012-05-15

    Results are presented from measurements of the discharge current and the factor of the discharge gap filling with spark channels during pulsed sliding discharges of opposite polarities in Ne, Ar, and Xe on an aluminum oxide ceramic surface. The measurements were performed in the regime of single pulses of submi-crosecond duration at discharge voltages of 0-12 kV with two discharge chambers with different thicknesses of the ceramic plate (0.4 and 0.17 cm) and different electrode gap lengths (4 and 10.3 cm) at gas pressures of 30 and 100 kPa. The results obtained for discharges of opposite polarities are compared with one another, and common features of discharges in three gases are revealed. It is shown that the filling of the discharge gap with spark channels in the gases under study is more efficient in the case of the positive polarity of the discharge voltage, except Xe at a pressure of 100 kPa in the electrode gap of length 10.3 cm. The quasi-homogeneous regime of discharge in each of the three gases is attained easier at lower gas pressures. Comparison of the data on the filling factors of the discharge gap and the peak currents of opposite-polarity discharges for each gas at a given pressure indicates that the higher the discharge current, the more densely the discharge gap is filled with spark channels.

  16. Space-filling polyhedral sorbents

    DOEpatents

    Haaland, Peter

    2016-06-21

    Solid sorbents, systems, and methods for pumping, storage, and purification of gases are disclosed. They derive from the dynamics of porous and free convection for specific gas/sorbent combinations and use space filling polyhedral microliths with facial aplanarities to produce sorbent arrays with interpenetrating interstitial manifolds of voids.

  17. Two-dimensional electron gas at surfaces of (001), (110), and (111) oriented SrTiO3 induced by Ar+-irradiation

    NASA Astrophysics Data System (ADS)

    Miao, Ludi; Du, Renzhong; Yin, Yuewei; Li, Qi

    2015-03-01

    Two-dimensional electron gases (2DEGs) at transition metal oxide surfaces and interfaces have attracted much attention due to their fascinating exotic properties such as superconductivity, large magneto-resistance (MR), and ferromagnetism. We have created 2DEGs at the surfaces of (001), (110), and (111) oriented SrTiO3 (STO) by Ar+-irradiation and measured their transport properties. The 2DEGs exhibit a fully metallic behavior with the 2D charge carrier density around 2 ×1014 cm-2 and the mobility as large as 5500 cm2V-1s-1 at low temperatures, which is tunable by electric fields applied through STO back gates. We have measured MR anisotropy of the 2DEGs at surfaces of STO with all orientations. We observed combinations of two types of components in their anisotropic MR at low temperatures. While the first type is an STO-orientation-independent two-fold component results from the Lorentz force effect, the second type shows stark differences between these 2DEGs as a consequence of distinct Fermi surface symmetries with different STO orientations. Indeed, it is four-fold for STO (001), two-fold for STO (110) and six-fold for STO (111), respectively.

  18. Strong magnetism observed in carbon nanoparticles produced by the laser vaporization of a carbon pellet in hydrogen-containing Ar balance gas.

    PubMed

    Asano, Hirohito; Muraki, Susumu; Endo, Hiroki; Bandow, Shunji; Iijima, Sumio

    2010-08-25

    Nanometer-scale carbon particles driven by the pulsed-laser vaporization of pelletized pure carbon powder at 1000 °C in a hydrogen-containing environment show anomalous magnetism like a superparamagnet, while the sample prepared in 100% of Ar does not show such magnetism. The observed magnetism was unchanged over months in the ambient. The structure of this nanomaterial resembles the foam of a laundry detergent and transmission electron microscopy indicates a clear corrugated line contrast. On the other hand, a sample without strong magnetism does not give such an image contrast. The x-ray diffraction pattern coincides with that of graphite and no other peak is detected. Thermogravimetry indicates that all samples completely burn out up to approx. 820 °C and no material remains after combustion, indicating that the sample does not contain impurity metals. Magnetization is easily saturated by ∼10,000 G at 280 K with no hysteresis, but the hysteresis appears at 4.2 K. This phenomenon is explained by introducing a crystalline anisotropy which restricts the motion of the magnetic moment and stabilizes the remnant magnetization at zero magnetic field. Magnitudes of the saturation magnetization are in the range of 1-5 emu G g(-1) at 4.2 K, which correspond to 0.002-0.01 Bohr magneton per carbon atom. This concentration may be increased by ten times or more, because only about 4-10% of particles have a magnetic domain in the present samples.

  19. Strong magnetism observed in carbon nanoparticles produced by the laser vaporization of a carbon pellet in hydrogen-containing Ar balance gas

    NASA Astrophysics Data System (ADS)

    Asano, Hirohito; Muraki, Susumu; Endo, Hiroki; Bandow, Shunji; Iijima, Sumio

    2010-08-01

    Nanometer-scale carbon particles driven by the pulsed-laser vaporization of pelletized pure carbon powder at 1000 °C in a hydrogen-containing environment show anomalous magnetism like a superparamagnet, while the sample prepared in 100% of Ar does not show such magnetism. The observed magnetism was unchanged over months in the ambient. The structure of this nanomaterial resembles the foam of a laundry detergent and transmission electron microscopy indicates a clear corrugated line contrast. On the other hand, a sample without strong magnetism does not give such an image contrast. The x-ray diffraction pattern coincides with that of graphite and no other peak is detected. Thermogravimetry indicates that all samples completely burn out up to approx. 820 °C and no material remains after combustion, indicating that the sample does not contain impurity metals. Magnetization is easily saturated by ~ 10 000 G at 280 K with no hysteresis, but the hysteresis appears at 4.2 K. This phenomenon is explained by introducing a crystalline anisotropy which restricts the motion of the magnetic moment and stabilizes the remnant magnetization at zero magnetic field. Magnitudes of the saturation magnetization are in the range of 1-5 emu G g - 1 at 4.2 K, which correspond to 0.002-0.01 Bohr magneton per carbon atom. This concentration may be increased by ten times or more, because only about 4-10% of particles have a magnetic domain in the present samples.

  20. Study of laser-generated debris free x-ray sources produced in a high-density linear Ar, Kr, Xe, Kr/Ar and Xe/Kr/Ar mixtures gas jets by 2 ω, sub-ps LLNL Titan laser

    NASA Astrophysics Data System (ADS)

    Kantsyrev, V. L.; Schultz, K. A.; Shlyaptseva, V. V.; Safronova, A. S.; Cooper, M. C.; Shrestha, I. K.; Petkov, E. E.; Stafford, A.; Moschella, J. J.; Schmidt-Petersen, M. T.; Butcher, C. J.; Kemp, G. E.; Andrews, S. D.; Fournier, K. B.

    2016-10-01

    The study of laser-generated debris-free x-ray sources in an underdense plasma produced in a high-density linear gas-puff jet was carried out at the LLNL Titan laser (2 ω, 45 J, sub-ps) with an intensity in the 10 um focal spot of 7 x 1019 W/cm2. A linear nozzle with a fast valve was used for the generation of a clusters/gas jet. X-ray diagnostics for the spectral region of 0.7 - 9 keV include: two spectrometers and pinhole cameras, and 3 groups of fast filtered detectors. Electron beams were measured with the EPPS magnetic spectrometer (>1 MeV) and Faraday cups (>72 keV). Spectralon/spectrometer devices were also used to measure absorption of laser radiation in the jets. New results were obtained on: anisotropic generation of x-rays (laser to x-ray conversion coefficient was >1%) and characteristics of laser-generated electron beams; evolution of x-ray generation with the location of the laser focus in a cluster-gas jet, and observations of a strong x-ray flash in some focusing regimes. Non-LTE kinetic modeling was used to estimate plasma parameters. UNR work supported by the DTRA Basic Research Award # HDTRA1-13-1-0033. Work at LLNL was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

  1. MALATANG: MApping the dense moLecular gAs in the sTrongest stAr-formiNg Galaxies

    NASA Astrophysics Data System (ADS)

    Gao, Yu; Zhang, Zhiyu; Greve, Thomas; MALATANG Team

    2017-01-01

    The MALATANG Large Program is a 390 hr campaign, using the heterodyne array HARP on the JCMT to map theHCN and HCO+ J = 4 - 3 line emission in 23 of the nearest IR-brightest galaxies beyond the Local Group. Theobservations will reach a sensitivity of 0.3 K km/s (~ 4.5 x 10^6 Msun) at linear resolutions of 0.2-2.8kpc. It is thefirst survey to systematically map the distribution of dense molecular gas out to large galactocentric distances in a statisticallysignificant sample of nearby galaxies. MALATANG will bridge the gap, in terms of physical scale and luminosity,between extragalactic (i.e., galaxy-integrated) and Galactic (i.e., single molecular clouds) observations. A primarygoal of the survey is to delineate for the first time the distributed dense gas star-formation relations, as traced by theHCN and HCO+ J = 4-3, on scales of ~1kpc across our targets. Exploring the behaviour of these star-formationrelations in low surface density regions found in the disks as well as in the nuclear regions where surface densitiesare high, will shed new light on whether such environments are host to fundamentally different star-formation modes.The MALATANG data products of resolved HCN and HCO+ J = 4-3 maps of 23 IR-bright local galaxies, will beof great value to the extragalactic community and, in and of themselves, carry significant legacy value. At the moment,about 50% (~195hrs) of the 390hrs of time allocated to MALATANG has been observed. We here show somevery preliminary results as well after introducing our project.

  2. Functional Promiscuity of Homologues of the Bacterial ArsA ATPases

    PubMed Central

    Castillo, Rostislav; Saier, Milton H.

    2010-01-01

    The ArsA ATPase of E. coli plays an essential role in arsenic detoxification. Published evidence implicates ArsA in the energization of As(III) efflux via the formation of an oxyanion-translocating complex with ArsB. In addition, eukaryotic ArsA homologues have several recognized functions unrelated to arsenic resistance. By aligning ArsA homologues, constructing phylogenetic trees, examining ArsA encoding operons, and estimating the probable coevolution of these homologues with putative transporters and auxiliary proteins unrelated to ArsB, we provide evidence for new functions for ArsA homologues. They may play roles in carbon starvation, gas vesicle biogenesis, and arsenic resistance. The results lead to the proposal that ArsA homologues energize four distinct and nonhomologous transporters, ArsB, ArsP, CstA, and Acr3. PMID:20981284

  3. Anionic chemistry of noble gases: formation of Mg-NG (NG = Xe, Kr, Ar) compounds under pressure.

    PubMed

    Miao, Mao-Sheng; Wang, Xiao-Li; Brgoch, Jakoah; Spera, Frank; Jackson, Matthew G; Kresse, Georg; Lin, Hai-Qing

    2015-11-11

    While often considered to be chemically inert, the reactivity of noble gas elements at elevated pressures is an important aspect of fundamental chemistry. The discovery of Xe oxidation transformed the doctrinal boundary of chemistry by showing that a complete electron shell is not inert to reaction. However, the reductive propensity, i.e., gaining electrons and forming anions, has not been proposed or examined for noble gas elements. In this work, we demonstrate, using first-principles electronic structure calculations coupled to an efficient structure prediction method, that Xe, Kr, and Ar can form thermodynamically stable compounds with Mg at high pressure (≥125, ≥250, and ≥250 GPa, respectively). The resulting compounds are metallic and the noble gas atoms are negatively charged, suggesting that chemical species with a completely filled shell can gain electrons, filling their outermost shell(s). Moreover, this work indicates that Mg2NG (NG = Xe, Kr, Ar) are high-pressure electrides with some of the electrons localized at interstitial sites enclosed by the surrounding atoms. Previous predictions showed that such electrides only form in Mg and its compounds at very high pressures (>500 GPa). These calculations also demonstrate strong chemical interactions between the Xe 5d orbitals and the quantized interstitial quasiatom (ISQ) orbitals, including the strong chemical bonding and electron transfer, revealing the chemical nature of the ISQ.

  4. Measuring 36Ar without H35Cl interference

    NASA Astrophysics Data System (ADS)

    Saxton, John

    2015-04-01

    Noble gas measurements are usually made in static mode, when the mass spectrometer sensitivity is inversely proportional to volume: this makes the building of very large instruments to obtain high mass resolution impracticable. A particularly challenging interference has hitherto been H35Cl, which differs in mass from 36Ar by 1 part in 3937. We have developed a method which makes improved use of the available MRP to remove interferences, and used it to obtain HCl-free 36Ar measurements on a multicollector instrument with MRP of only ~6000 (MRP= mass resolving power = m/dm 5-95% on side of peak). By arranging that the target mass position on a minor isotope (e.g. 36Ar), from which the interference must be removed, coincides with the ~50% point on the side of a major isotope (e.g. 40Ar), it is possible both to set the mass accurately and to verify the mass position and stability during measurements. The peak top of 40Ar is measured in a separate mass step. Two small corrections are necessary. One compensates for the residual HCl tail at the 36Ar position. The other arises because the peak is not totally flat in the region of interest: 40Ar and 36Ar+HCl are measured on the peak top, whilst 36Ar is measured at the extreme edge, with slightly lower efficiency. The required correction parameters can be obtained from a series of air calibrations with different target/interference ratios. With samples containing 4x10-15to 3x10-14moles of 40Ar, 36Ar/40Ar was measured, without HCl interference, to a 1σ precision of 0.5%, only slightly worse than counting statistics. This is potentially useful for 40Ar/39Ar dating, where 36Ar is used to correct for trapped air, and may be particularly significant for smaller or younger samples.

  5. Hydrogen Filling Station

    SciTech Connect

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    Hydrogen is an environmentally attractive transportation fuel that has the potential to displace fossil fuels. The Freedom CAR and Freedom FUEL initiatives emphasize the importance of hydrogen as a future transportation fuel. Presently, Las Vegas has one hydrogen fueling station powered by natural gas. However, the use of traditional sources of energy to produce hydrogen does not maximize the benefit. The hydrogen fueling station developed under this grant used electrolysis units and solar energy to produce hydrogen fuel. Water and electricity are furnished to the unit and the output is hydrogen and oxygen. Three vehicles were converted to utilize the hydrogen produced at the station. The vehicles were all equipped with different types of technologies. The vehicles were used in the day-to-day operation of the Las Vegas Valley Water District and monitoring was performed on efficiency, reliability and maintenance requirements. The research and demonstration utilized for the reconfiguration of these vehicles could lead to new technologies in vehicle development that could make hydrogen-fueled vehicles more cost effective, economical, efficient and more widely used. In order to advance the development of a hydrogen future in Southern Nevada, project partners recognized a need to bring various entities involved in hydrogen development and deployment together as a means of sharing knowledge and eliminating duplication of efforts. A road-mapping session was held in Las Vegas in June 2006. The Nevada State Energy Office, representatives from DOE, DOE contractors and LANL, NETL, NREL were present. Leadership from the National hydrogen Association Board of Directors also attended. As a result of this session, a roadmap for hydrogen development was created. This roadmap has the ability to become a tool for use by other road-mapping efforts in the hydrogen community. It could also become a standard template for other states or even countries to approach planning for a hydrogen

  6. Ion-kinetic simulations of D-3He gas-filled inertial confinement fusion target implosions with moderate to large Knudsen number

    NASA Astrophysics Data System (ADS)

    Larroche, O.; Rinderknecht, H. G.; Rosenberg, M. J.; Hoffman, N. M.; Atzeni, S.; Petrasso, R. D.; Amendt, P. A.; Séguin, F. H.

    2016-01-01

    Experiments designed to investigate the transition to non-collisional behavior in D3He-gas inertial confinement fusion target implosions display increasingly large discrepancies with respect to simulations by standard hydrodynamics codes as the expected ion mean-free-paths λc increase with respect to the target radius R (i.e., when the Knudsen number NK=λc/R grows). To take properly into account large NK's, multi-ion-species Vlasov-Fokker-Planck computations of the inner gas in the capsules have been performed, for two different values of NK, one moderate and one large. The results, including nuclear yield, reactivity-weighted ion temperatures, nuclear emissivities, and surface brightness, have been compared with the experimental data and with the results of hydrodynamical simulations, some of which include an ad hoc modeling of kinetic effects. The experimental results are quite accurately rendered by the kinetic calculations in the smaller-NK case, much better than by the hydrodynamical calculations. The kinetic effects at play in this case are thus correctly understood. However, in the higher-NK case, the agreement is much worse. The remaining discrepancies are shown to arise from kinetic phenomena (e.g., inter-species diffusion) occurring at the gas-pusher interface, which should be investigated in the future work.

  7. Ion-kinetic simulations of D-3He gas-filled inertial confinement fusion target implosions with moderate to large Knudsen number

    DOE PAGES

    Larroche, O.; Rinderknecht, H. G.; Rosenberg, M. J.; ...

    2016-01-06

    Experiments designed to investigate the transition to non-collisional behavior in D3He-gas inertial confinement fusion target implosions display increasingly large discrepancies with respect to simulations by standard hydrodynamics codes as the expected ion mean-free-paths λc increase with respect to the target radius R (i.e., when the Knudsen number NK = λc/R grows). To take properly into account large NK's, multi-ion-species Vlasov-Fokker-Planck computations of the inner gas in the capsules have been performed, for two different values of NK, one moderate and one large. The results, including nuclear yield, reactivity-weighted ion temperatures, nuclear emissivities, and surface brightness, have been compared with themore » experimental data and with the results of hydrodynamical simulations, some of which include an ad hocmodeling of kinetic effects. The experimental results are quite accurately rendered by the kinetic calculations in the smaller-NK case, much better than by the hydrodynamical calculations. The kinetic effects at play in this case are thus correctly understood. However, in the higher-NK case, the agreement is much worse. Furthermore, the remaining discrepancies are shown to arise from kinetic phenomena (e.g., inter-species diffusion) occurring at the gas-pusher interface, which should be investigated in the future work.« less

  8. Ion-kinetic simulations of D-3He gas-filled inertial confinement fusion target implosions with moderate to large Knudsen number

    SciTech Connect

    Larroche, O.; Rinderknecht, H. G.; Rosenberg, M. J.; Hoffman, N. M.; Atzeni, S.; Petrasso, R. D.; Amendt, P. A.; Seguin, F. H.

    2016-01-06

    Experiments designed to investigate the transition to non-collisional behavior in D3He-gas inertial confinement fusion target implosions display increasingly large discrepancies with respect to simulations by standard hydrodynamics codes as the expected ion mean-free-paths λc increase with respect to the target radius R (i.e., when the Knudsen number NK = λc/R grows). To take properly into account large NK's, multi-ion-species Vlasov-Fokker-Planck computations of the inner gas in the capsules have been performed, for two different values of NK, one moderate and one large. The results, including nuclear yield, reactivity-weighted ion temperatures, nuclear emissivities, and surface brightness, have been compared with the experimental data and with the results of hydrodynamical simulations, some of which include an ad hocmodeling of kinetic effects. The experimental results are quite accurately rendered by the kinetic calculations in the smaller-NK case, much better than by the hydrodynamical calculations. The kinetic effects at play in this case are thus correctly understood. However, in the higher-NK case, the agreement is much worse. Furthermore, the remaining discrepancies are shown to arise from kinetic phenomena (e.g., inter-species diffusion) occurring at the gas-pusher interface, which should be investigated in the future work.

  9. Towards establishing high-precision 40Ar/39Ar chronologies for distal tephra archives

    NASA Astrophysics Data System (ADS)

    Mark, D. F.

    2012-12-01

    39Ar recoil effects. These effects are amplified by a high surface area to volume ratio of glass shards and thus short effective diffusion dimensions (radii of glass shards). I will discuss the application of 40Ar/39Ar geochronology to distal tephra and present two methodologies for establishing absolute 40Ar/39Ar age constraints for distal tephra archives. Two case studies will be presented: [1] dating of distal tephra in Lake Suigetsu, Japan by establishing robust correlations between proximal (crystal-rich) and distal (crystal-poor) volcanic deposits, and [2] dating of distal Toba tephra throughout peninsular of India by targeting of sub-100 μm shards of biotite. A look at future development in 40Ar/39Ar geochronology and noble gas mass spectrometry with implications for tephrochronology studies will conclude the presentation.

  10. Practical reactor production of 41Ar from argon clathrate.

    PubMed

    Mercer, J R; Duke, M J; McQuarrie, S A

    2000-06-01

    The radionuclide 41Ar has many ideal properties as a gas flow tracer. However, the modest cross-section of 40Ar for thermal neutron activation makes preparation of suitable activities of 41Ar technically difficult particularly for low flux reactors. Argon can however be trapped in a molecular complex called a clathrate that can then be irradiated. We prepared argon clathrate and explored its irradiation and stability characteristics. Argon clathrate can be used to provide gigabecquerel quantities of 41Ar even with low power reactors.

  11. Getting a prescription filled

    MedlinePlus

    ... prescription filled; Drugs - how to get prescription filled; Pharmacy - mail order; Pharmacy - internet; Types of pharmacies ... paper prescription that you take to a local pharmacy Calling or e-mailing a pharmacy to order ...

  12. 39Ar- 40Ar ages of martian nakhlites

    NASA Astrophysics Data System (ADS)

    Park, Jisun; Garrison, Daniel H.; Bogard, Donald D.

    2009-04-01

    We report 39Ar- 40Ar ages of whole rock (WR) and plagioclase and pyroxene mineral separates of nakhlites MIL 03346 and Y-000593, and of WR samples of nakhlites NWA 998 and Nakhla. All age spectra are complex and indicate variable degrees of 39Ar recoil and variable amounts of trapped 40Ar in the samples. Thus, we examine possible Ar-Ar ages in several ways. From consideration of both limited plateau ages and isochron ages, we prefer Ar-Ar ages of NWA 998 = 1334 ± 11 Ma, MIL 03346 = 1368 ± 83 Ma (mesostasis) and 1334 ± 54 Ma (pyroxene), Y-000593 = 1367 ± 7 Ma, and Nakhla = 1357 ± 11 Ma, (2 σ errors). For NWA 998 and MIL 03346 the Ar-Ar ages are within uncertainties of preliminary Rb-Sr isochron ages reported in the literature. These Ar-Ar ages for Y-000593 and Nakhla are several Ma older than Sm-Nd ages reported in the literature. We conclude that the major factor in producing Ar-Ar ages slightly too old is the presence of small amounts of trapped martian or terrestrial 40Ar on weathered grain surfaces that was degassed along with the first several percent of 39Ar. A total K- 40Ar isochron for WR and mineral data from five nakhlites analyzed by us, plus Lafayette data in the literature, gives an isochron age of 1325 ± 18 Ma (2 σ). We emphasize the precision of this isochron over the value of the isochron age. Our Ar-Ar data are consistent with a common formation age for nakhlites. The cosmic-ray exposure (CRE) age for NWA 998 of ˜12 Ma is also similar to CRE ages for other nakhlites.

  13. Lower-hybrid breakdown of gas in the field of a current-carrying loop in a plasma-filled magnetic confinement system

    SciTech Connect

    Golubyatnikov, G.Y.; Egorov, S.V.; Eremin, B.G.

    1995-02-01

    Experiments have been carried out on the breakdown dynamics and the formation of an ionized region in the field of a current-carrying loop in a large magnetic confinement system filled with background plasma. The loop radiates in the lower-hybrid frequency range. Breakdown is observed to generate a strong local perturbation of plasma: {Delta}N/N{approx_equal} 10{sup 2}, {Delta}T{sub e}/T{sub e} {approx_equal} 50. The perturbed region has a transverse dimension roughly equal to the antenna diameter. Along the direction of the magnetic field, this region is localized between the magnetic mirrors. The density begins to increase throughout the volume of this magnetic tube at the instant at which the field arises at the antenna. Analysis of experimental data leads to the conclusion that the primary cause of the fast ionization along the magnetic force tube is the excitation of an intense beam of lower-hybrid plasma waves. 10 refs., 5 figs., 2 tabs.

  14. Argon behaviour in gem-quality orthoclase from Madagascar: Experiments and some consequences for 40Ar/39Ar geochronology

    NASA Astrophysics Data System (ADS)

    Arnaud, N. O.; Kelley, S. P.

    1997-08-01

    into which 40Ar diffused in nature to yield apparent excess argon, but which were then filled with corresponding 39Ar during cycle heating. The K-feldspar structure illuminated by these studies is one in which argon diffuses through the lattice over distances of at least 100 pm probably via a volume diffusion mechanism to the grain boundaries. However, close to the surface argon may also diffuse along fast diffusion paths resulting from natural traps opened during sample preparation. Though restricted to very small volumes of gas in the case of the Itrongay orthoclase gem, the existence of the traps has potentially important consequences for 40Ar/39Ar geochronology applied to K-feldspars.

  15. Laser parametric instability experiments of a 3ω, 15 kJ, 6-ns laser pulse in gas-filled hohlraums at the Ligne d'Intégration Laser facility

    SciTech Connect

    Rousseaux, C.; Huser, G.; Loiseau, P.; Casanova, M.; Alozy, E.; Villette, B.; Wrobel, R.; Henry, O.; Raffestin, D.

    2015-02-15

    Experimental investigation of stimulated Raman (SRS) and Brillouin (SBS) scattering have been obtained at the Ligne-d'Intégration-Laser facility (LIL, CEA-Cesta, France). The parametric instabilities (LPI) are driven by firing four laser beamlets (one quad) into millimeter size, gas-filled hohlraum targets. A quad delivers energy on target of 15 kJ at 3ω in a 6-ns shaped laser pulse. The quad is focused by means of 3ω gratings and is optically smoothed with a kinoform phase plate and with smoothing by spectral dispersion-like 2 GHz and/or 14 GHz laser bandwidth. Open- and closed-geometry hohlraums have been used, all being filled with 1-atm, neo-pentane (C{sub 5}H{sub 12}) gas. For SRS and SBS studies, the light backscattered into the focusing optics is analyzed with spectral and time resolutions. Near-backscattered light at 3ω and transmitted light at 3ω are also monitored in the open geometry case. Depending on the target geometry (plasma length and hydrodynamic evolution of the plasma), it is shown that, at maximum laser intensity about 9 × 10{sup 14} W/cm{sup 2}, Raman reflectivity noticeably increases up to 30% in 4-mm long plasmas while SBS stays below 10%. Consequently, laser transmission through long plasmas drops to about 10% of incident energy. Adding 14 GHz bandwidth to the laser always reduces LPI reflectivities, although this reduction is not dramatic.

  16. Small tritium filling and monitoring apparatus for particle beam inertial confinement fusion targets.

    PubMed

    Chang, J; Leeper, R J; Martinez, C; McMurtry, W M

    1980-03-01

    A small gas filling apparatus has been developed to fill a particle beam ICF target with D-T gas mixture seconds before the target is irradiated. Included in the filling apparatus is a novel miniature pressure monitor which determines quantitatively the fill pressure by counting the rate of Beta particles emitted by the decaying tritium atoms.

  17. Subterranean production of neutrons, 39Ar and 21Ne: Rates and uncertainties

    NASA Astrophysics Data System (ADS)

    Šrámek, Ondřej; Stevens, Lauren; McDonough, William F.; Mukhopadhyay, Sujoy; Peterson, R. J.

    2017-01-01

    Accurate understanding of the subsurface production rate of the radionuclide 39Ar is necessary for argon dating techniques and noble gas geochemistry of the shallow and the deep Earth, and is also of interest to the WIMP dark matter experimental particle physics community. Our new calculations of subsurface production of neutrons, 21Ne , and 39Ar take advantage of the state-of-the-art reliable tools of nuclear physics to obtain reaction cross sections and spectra (TALYS) and to evaluate neutron propagation in rock (MCNP6). We discuss our method and results in relation to previous studies and show the relative importance of various neutron, 21Ne , and 39Ar nucleogenic production channels. Uncertainty in nuclear reaction cross sections, which is the major contributor to overall calculation uncertainty, is estimated from variability in existing experimental and library data. Depending on selected rock composition, on the order of 107-1010 α particles are produced in one kilogram of rock per year (order of 1-103 kg-1 s-1); the number of produced neutrons is lower by ∼ 6 orders of magnitude, 21Ne production rate drops by an additional factor of 15-20, and another one order of magnitude or more is dropped in production of 39Ar. Our calculation yields a nucleogenic 21Ne /4He production ratio of (4.6 ± 0.6) ×10-8 in Continental Crust and (4.2 ± 0.5) ×10-8 in Oceanic Crust and Depleted Mantle. Calculated 39Ar production rates span a great range from 29 ± 9 atoms kg-rock-1 yr-1 in the K-Th-U-enriched Upper Continental Crust to (2.6 ± 0.8) × 10-4 atoms kg-rock-1 yr-1 in Depleted Upper Mantle. Nucleogenic 39Ar production exceeds the cosmogenic production below ∼700 m depth and thus, affects radiometric ages of groundwater. The 39Ar chronometer, which fills in a gap between 3H and 14C , is particularly important given the need to tap deep reservoirs of ancient drinking water.

  18. Characterization of Mg/Al butt joints welded by gas tungsten arc filling with Zn–29.5Al–0.5Ti filler metal

    SciTech Connect

    Liu, Fei; Wang, Hongyang; Liu, Liming

    2014-04-01

    The multivariate alloying design of a welding joint is used in the Mg to Al welding process. A Zn–29.5Al–0.5Ti alloy is added as filler metal in gas tungsten arc welding of Mg and Al alloy joint based on the analysis of Al and Mg alloy characteristics. The tensile strength, microstructure, and phase constitution of the weld seam are analyzed. The formation of brittle and hard Mg–Al intermetallic compounds is avoided because of the effects of Zn, Al, and Ti. The average tensile strength of the joint is 148 MPa. Al{sub 3}Ti is first precipitated and functions as the nucleus of heterogeneous nucleation during solidification. Moreover, the precipitated Al–MgZn{sub 2} hypoeutectic phase exhibited a feather-like structure, which enhances the property of the Mg–Al dissimilar joint. - Highlights: • Mg alloy AZ31B and Al alloy 6061 are butt welded by fusion welding. • The effect of Ti in filler metal is investigated. • The formation of Mg–Al intermetallic compounds is avoided.

  19. Atmospheric pressure plasma jet in Ar and Ar/H{sub 2}O mixtures: Optical emission spectroscopy and temperature measurements

    SciTech Connect

    Sarani, Abdollah; Leys, Christophe; Nikiforov, Anton Yu.

    2010-06-15

    An atmospheric pressure plasma jet generated in Ar/water vapor mixtures has been investigated and the effect of water content on plasma properties has been studied. Plasma generated in Ar/water (0.05%) mixture shows higher intensity of OH radicals in emission spectra than pure argon alone. Plasma density has been estimated from current measurement and is in order of 1.5x10{sup 13} cm{sup -3}. Electron temperature has been estimated as 0.97 eV in pure Ar and it decreases with an increase in water content in plasma. The gas temperature has been determined by fitting of the experimental spectra and using the Boltzmann plot method. The gas temperature increases with the addition of water to feed gas from 620 K in pure Ar up to 1130 K for 0.76%H{sub 2}O.

  20. Pulsed Electrical Discharge in a Gas Bubble in Water

    NASA Astrophysics Data System (ADS)

    Schaefer, Erica; Gershman, Sophia; Mozgina, Oksana

    2005-10-01

    This experiment is an investigation of the electrical and optical characteristics of a pulsed electrical discharge ignited in a gas bubble in water in a needle-to-plane electrode geometry. Argon or oxygen gas is fed through a platinum hypodermic needle that serves as the high voltage electrode. The gas filled bubble forms at the high voltage electrode with the tip of the needle inside the bubble. The discharge in the gas bubble in water is produced by applying 5 -- 15 kV, microsecond long rectangular pulses between the electrodes submerged in water. The voltage across the electrodes and the current are measured as functions of time. Electrical measurements suggest a discharge ignited in the bubble (composed of the bubbled gas and water vapor) without breakdown of the entire water filled electrode gap. Time-resolved optical emission measurements are taken in the areas of the spectrum corresponding to the main reactive species produced in the discharge, e.g. OH 309 nm, Ar 750 nm, and O 777 nm emissions using optical filters. The discharge properties are investigated as a function of the applied voltage, the distance between the electrodes, the gas in the bubble (Ar or O2). Work supported by the US Army, Picatinny Arsenal, NJ and the US DOE (Contract number DE-AC02-76CH03073).

  1. Insights into gas-phase structural conformers of hydrated rubidium and cesium cations, M(+)(H2O)(n)Ar (M = Rb, Cs; n = 3-5), using infrared photodissociation spectroscopy.

    PubMed

    Ke, Haochen; van der Linde, Christian; Lisy, James M

    2014-02-27

    Infrared photodissociation (IRPD) spectra of M(+)(H2O)nAr (M = Rb, Cs; n = 3-5) with simultaneous monitoring of [Ar] and [Ar+H2O] fragmentation channels are reported. The comparison between the spectral features in the two channels and corresponding energy analysis provide spectral assignments of the stable structural conformers and insight into the competition between ion-water electrostatic and water-water hydrogen bonding interactions. Results show that as the level of hydration increases, the water-water interaction exhibits the tendency to dominate over the ion-water interaction. Cyclic water tetramer and water pentamer substructures appear in Cs(+)(H2O)4Ar and Cs(+)(H2O)5Ar systems, respectively. However, cyclic water tetramer and pentamer structures were not observed for Rb(+)(H2O)4Ar and Rb(+)(H2O)5Ar systems, respectively, due to the stronger influence of the rubidium ion-water electrostatic interaction. The energy analysis, including the available internal energy and the IR photon energy, helped provide an experimental estimate of water binding energies.

  2. Ar/Ar Dating Independent of Monitor Standard Ages

    NASA Astrophysics Data System (ADS)

    Boswell, S.; Hemming, S. R.

    2015-12-01

    Because the reported age of an analyzed sample is dependent on the age of the co-irradiated monitor standard(s), Ar/Ar dating is a relative dating technique. There is disagreement at the 1% scale in the age of commonly used monitor standards, and there is a great need to improve the inter-laboratory calibrations. Additionally, new approaches and insights are needed to meet the challenge of bringing the Ar/Ar chronometer to the highest possible precision and accuracy. In this spirit, we present a conceptual framework for Ar/Ar dating that does not depend on the age of monitor standards, but only on the K content of a solid standard. The concept is demonstrated by introducing a re-expressed irradiation parameter (JK) that depends on the ratio of 39ArK to 40Ar* rather than the 40Ar*/39ArK ratio. JK is equivalent to the traditional irradiation parameter J and is defined as JK = (39Ar/40K) • (λ/λe). The ultimate precision and accuracy of the method will depend on how precisely and accurately the 39Ar and 40K can be estimated, and will require isotope dilution measurements of both from the same aliquot. We are testing the workability of our technique at the 1% level by measuring weighed and irradiated hornblende and biotite monitor standards using GLO-1 glauconite to define a calibration curve for argon signals versus abundance.

  3. Investigating Diffusion and Entropy with Carbon Dioxide-Filled Balloons

    ERIC Educational Resources Information Center

    Jadrich, James; Bruxvoort, Crystal

    2010-01-01

    Fill an ordinary latex balloon with helium gas and you know what to expect. Over the next day or two the volume will decrease noticeably as helium escapes from the balloon. So what happens when a latex balloon is filled with carbon dioxide gas? Surprisingly, carbon dioxide balloons deflate at rates as much as an order of magnitude faster than…

  4. 40Ar/39Ar Dating of Volcanic Glass

    NASA Astrophysics Data System (ADS)

    Morgan, L. E.; Renne, P. R.; Watkins, J. M.

    2007-12-01

    Application of the 40Ar/39Ar method to volcanic glasses has been somewhat stigmatized following several studies demonstrating secondary mobility of K and Ar. Much of the stigma is unwarranted, however, since most studies only impugned the reliability of the K-Ar and 40Ar/39Ar techniques when applied to glass shards rather than obsidian clasts with low surface area to volume ratios. We provide further evidence for problematic K loss and/or 39Ar recoil ejection from glass shards in 40Ar/39Ar step heating results for comagmatic feldspars and shards. In an extreme case, the plateau age of the feldspars (0.17 ± 0.03 Ma at 2σ) is significantly younger than the plateau age of the glass (0.85 ± 0.05 Ma at 2σ). If the feldspar age is reasonably interpreted as the eruption age of the ash, it is likely that the glass shards experienced K and/or 39Ar loss. Electron microprobe analyses of the glass shards have low totals (~93%) and no systematic lateral variability (i.e., diffusion gradients) in K, suggesting that the lengthscale of the glass shards is smaller than the lengthscale of K diffusion. Obsidian clasts should not be as susceptible to K loss since any hydrated (K-depleted) volume represents a small fraction of the total material and can often be physically removed prior to analysis. Samples described here are detrital obsidian clasts from the Afar region of Ethiopia. Evidence from Fourier Transform Infrared Spectroscopy (FTIR), and previous work by Anovitz (1999), confirm that the scale of water and potassium mobility are often small in comparison to the size of obsidian clasts but large enough to effect the bulk composition of glass shards. This expectation is confirmed in another tuff wherein comagmatic obsidian clasts and sanidine phenocrysts yield indistinguishable 40Ar/39Ar ages of 4.4 Ma High abundances of non-radiogenic 40Ar, and kinetic fractionation of Ar isotopes during quenching and/or laboratory degassing resulting in incomplete equilibration between

  5. Combined K-Ar and 40Ar/39Ar dating of the upper Jaramillo reversal

    NASA Astrophysics Data System (ADS)

    Guillou, Herve; Carracedo, Juan Carlos; Kissel, Catherine; Laj, Carlo; Nomade, Sebastien; Perez Torrado, Francisco Jose; Rodriguez Gonzalez, Alejandro; Wandres, Camille

    2013-04-01

    The Jaramillo subchron was first evidenced in 1966 (Doell and Dalrymple) through the Rhyolotic domes of the Valles Caldera, New Mexico (USA). 40Ar/39Ar studies achieved by Spell et McDougall (1992), Spell et Harrison (1993), Izett and Obradovich (1994) and Singer et al. (1994) defined the base of this subchron at 1053±6 ka, and the ceiling at 986±5 ka. Channell et al. (2009) delimited the age of the Jaramillo subchron by astronomic calibration (base 1071 ka, top 990 ka). To provide additional absolute ages on this geomagnetic period, which is critical to improve our knowledge of the earth magnetic field behaviour, we have carried out a study combining paleomagnetism and isotopic dating of a lava sequence from Tenerife island. This sequence of basaltic lava flows is some 500 m thick. The first 400 m present, based on field magnetometer measurements, normal polarity lavas, with dykes of normal and reverse polarity, passing at the top to reverse polarity lavas. Preliminary K-Ar ages bracketed this sequence between 1018 ± 18 ka and 978 ± 17 ka. Therefore, the upper Jaramillo reversal at least appeared to be potentially recorded in this sequence. A more detailed paleomagnetic study was then carried out to more precisely delimit the reversal itself (see Laj et al., session EMRP3.4). We have undertaken 40Ar/39Ar incremental heating and unspiked K-Ar experiments on groundmass from four transitionally magnetized flows. The first transitional flow is K-Ar dated at 993 ± 18 ka and 40Ar/39Ar dated at 991 ± 13 ka, the second at 981 ± 17 ka (K-Ar) and 1000 ± 13 ka (40Ar/39Ar), the third at 950 ± 17 ka (K-Ar) and 1000 ± 8 ka (40Ar/39Ar) and the fourth at 984 ± 17 ka (K-Ar) and 977 ± 12 (40Ar/39Ar). 40Ar/39Ar ages and K-Ar ages (relative to FCT 28.02 Ma) are indistinguishable at 2σ. The age of the upper boundary of the Jaramillo event calculated combining 40Ar/39Ar ages and K-Ar ages is 992 ± 6 ka, in agreement with previous estimates.

  6. Photoionization of Ar VIII

    NASA Astrophysics Data System (ADS)

    Liang, Liang; Jiang, Wen-xian; Zhou, Chao

    2017-01-01

    The photoionization cross section, energy levels and widths of 22 Rydberg series (in the autoionization region) for Na-like Ar VIII were investigated by using of R-matrix method. The relativistic distorted-wave method is used to calculate the radial functions, and QB method of Quigly-Berrington [Quigley et al. 1998] is employed to calculate the resonance levels and widths. We have identified the formant in the figure of the photoionization cross section.

  7. Comparison of cryogenic and differential flow (forward and reverse fill/flush) modulators and applications to the analysis of heavy petroleum cuts by high-temperature comprehensive gas chromatography.

    PubMed

    Duhamel, Chloé; Cardinael, Pascal; Peulon-Agasse, Valérie; Firor, Roger; Pascaud, Laurent; Semard-Jousset, Gaëlle; Giusti, Pierre; Livadaris, Vincent

    2015-03-27

    The development of new efficient conversion processes to transform heavy petroleum fractions into valuable products, such as diesel, requires improved chemical knowledge of the latter. High-temperature comprehensive gas chromatography (HT-GC × GC) has proven to be a powerful technique for characterizing such complex samples. This paper reports on an evaluation of the performances of four different differential flow modulators, including two original ones that have not been previously described in the literature, in terms of dispersion, peak intensity, peak capacity and overloading. These modulators, all of which are based on Agilent capillary flow technology (CFT), are forward fill/flush (FFF) differential flow modulators with an integrated collection channel or an adjustable channel (new) and reverse fill/flush (RFF) differential flow modulators with an integrated collection channel (new) or an adjustable channel. First, the optimization of the collection channel dimensions is described. Second, an RFF and an FFF differential flow modulator possessing the same collection channel were compared. The reverse differential flow modulation significantly reduced band broadening compared to forward differential flow modulation, and the peak intensity doubled for every modulated peak when an RFF differential flow modulator was used. Then, an RFF differential flow modulator and CO2 dual-jet modulator were compared. Whereas the percentages of separation space used were similar (61% with the HT-GC × GC method using a cryogenic modulator and 59% with the method using an RFF differential flow modulator), the peak capacities were at least three times more important with differential flow modulation due to the greater length of the column used in the second dimension. The results demonstrate that the RFF differential flow modulator is an excellent tool for studying heavy petroleum cuts. It demonstrates the best performances and it is the most versatile modulator. In its two

  8. Resonant proton scattering on 46Ar using the Active-Target Time Projection Chamber

    NASA Astrophysics Data System (ADS)

    Bradt, J.; Ahn, T.; Ayyad Limonge, Y.; Bazin, D.; Beceiro Novo, S.; Carpenter, L.; Kuchera, M. P.; Lynch, W.; Mittig, W.; Rost, S.; Watwood, N.; Barney, J.; Datta, U.; Estee, J.; Gillibert, A.; Manfredi, J.; Morfouace, P.; Perez Loureiro, D.; Pollacco, E.; Sammut, J.; Sweany, S.

    2016-09-01

    A well-known technique for studying the single-particle properties of neutron-rich nuclei is to use resonant proton scattering on a parent nucleus to populate the isobaric analog states of the corresponding neutron-rich nucleus. The locations and amplitudes of these resonances are directly related to the structure of the nucleus of interest by isospin symmetry. We performed an experiment of this type at the National Superconducting Cyclotron Laboratory to commission the recently completed Active-Target Time Projection Chamber (AT-TPC). A 4.6-MeV/u radioactive beam of 46Ar was injected into the AT-TPC. The detector was filled with isobutane gas-which provided the protons for the reaction and served as the tracking medium-and placed inside a 2-T magnetic field. We will present preliminary results from this experiment and discuss the benefits of the active-target method for this type of measurement.

  9. Mars’ atmospheric history derived from upper-atmosphere measurements of 38Ar/36Ar

    NASA Astrophysics Data System (ADS)

    Jakosky, B. M.; Slipski, M.; Benna, M.; Mahaffy, P.; Elrod, M.; Yelle, R.; Stone, S.; Alsaeed, N.

    2017-03-01

    The history of Mars’ atmosphere is important for understanding the geological evolution and potential habitability of the planet. We determine the amount of gas lost to space through time using measurements of the upper-atmospheric structure made by the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. We derive the structure of 38Ar/36Ar between the homopause and exobase altitudes. Fractionation of argon occurs as a result of loss of gas to space by pickup-ion sputtering, which preferentially removes the lighter atom. The measurements require that 66% of the atmospheric argon has been lost to space. Thus, a large fraction of Mars’ atmospheric gas has been lost to space, contributing to the transition in climate from an early, warm, wet environment to today’s cold, dry atmosphere.

  10. Effect of surface derived hydrocarbon impurities on Ar plasma properties

    SciTech Connect

    Fox-Lyon, Nick; Oehrlein, Gottlieb S.; Godyak, Valery

    2014-05-15

    The authors report on Langmuir probe measurements that show that hydrocarbon surfaces in contact with Ar plasma cause changes of electron energy distribution functions due to the flux of hydrogen and carbon atoms released by the surfaces. The authors compare the impact on plasma properties of hydrocarbon species gasified from an etching hydrocarbon surface with injection of gaseous hydrocarbons into Ar plasma. They find that both kinds of hydrocarbon injections decrease electron density and slightly increase electron temperatures of low pressure Ar plasma. For low percentages of impurities (∼1% impurity in Ar plasma explored here), surface-derived hydrocarbon species and gas phase injected hydrocarbon molecules cause similar changes of plasma properties for the same number of hydrocarbon molecules injected into Ar with a decrease in electron density of ∼4%.

  11. Acoustic resonance spectroscopy (ARS): ARS300 operations manual, software version 2.01

    SciTech Connect

    1996-07-25

    Acoustic Resonance Spectroscopy (ARS) is a nondestructive evaluation technology developed at the Los Alamos National Laboratory. The ARS technique is a fast, safe, and nonintrusive technique that is particularly useful when a large number of objects need to be tested. Any physical object, whether solid, hollow, or fluid filled, has many modes of vibration. These modes of vibration, commonly referred to as the natural resonant modes or resonant frequencies, are determined by the object`s shape, size, and physical properties, such as elastic moduli, speed of sound, and density. If the object is mechanically excited at frequencies corresponding to its characteristic natural vibrational modes, a resonance effect can be observed when small excitation energies produce large amplitude vibrations in the object. At other excitation frequencies, i.e., vibrational response of the object is minimal.

  12. Production of 37Ar in The University of Texas TRIGA reactor facility

    SciTech Connect

    Egnatuk, Christine M.; Lowrey, Justin; Biegalski, S.; Bowyer, Ted W.; Haas, Derek A.; Orrell, John L.; Woods, Vincent T.; Keillor, Martin E.

    2011-06-19

    The detection of {sup 37}Ar is important for on-site inspections for the Comprehensive Nuclear-Test-Ban Treaty monitoring. In an underground nuclear explosion this radionuclide is produced by {sup 40}Ca(n,{alpha}){sup 37}Ar reaction in surrounding soil and rock. With a half-life of 35 days, {sup 37}Ar provides a signal useful for confirming the location of an underground nuclear event. An ultra-low-background proportional counter developed by Pacific Northwest National Laboratory is used to detect {sup 37}Ar, which decays via electron capture. The irradiation of Ar gas at natural enrichment in the 3L facility within the Mark II TRIGA reactor facility at The University of Texas at Austin provides a source of {sup 37}Ar for the calibration of the detector. The {sup 41}Ar activity is measured by the gamma activity using an HPGe detector after the sample is removed from the core. Using the {sup 41}Ar/{sup 37}Ar production ratio and the {sup 41}Ar activity, the amount of {sup 37}Ar created is calculated. The {sup 41}Ar decays quickly (half-life of 109.34 minutes) leaving a radioactive sample of high purity {sup 37}Ar and only trace levels of {sup 39}Ar.

  13. Filled Landau levels in neutral quantum gases

    SciTech Connect

    Oehberg, P.; Juzeliunas, G.; Ruseckas, J.; Fleischhauer, M.

    2005-11-15

    We consider the signatures of the integer quantum Hall effect in a degenerate gas of electrically neutral atomic fermions. An effective magnetic field is achieved by applying two incident light beams with a high orbital angular momentum. We show how states corresponding to completely filled Landau levels are obtained and discuss various possibilities to measure the incompressible nature of the trapped two-dimensional gas.

  14. Filling a Conical Cavity

    NASA Astrophysics Data System (ADS)

    Nye, Kyle; Eslam-Panah, Azar

    2016-11-01

    Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth.

  15. 40Ar/39Ar Interlaboratory Calibration into the Holocene.

    NASA Astrophysics Data System (ADS)

    Heizler, M. T.; Jicha, B.; Koppers, A. A. P.; Miggins, D. P.

    2015-12-01

    Advances in 40Ar/39Ar analytical precision for very young rocks requires collaborative efforts amongst argon geochronology labs to demonstrate age reproducibility commensurate with high precision. NM Tech (NMT), the University of Wisconsin (UW) and Oregon State University (OSU) have each dated Quaternary flux monitor standard AC-2 sanidine (~1.185 Ma), a blind sanidine described as being 50-100 ka (BS) and sanidine from the Qixiangshan (QIX) flow (~10 ka), Changbaishan volcano, China. The samples were irradiated in a single package with FC-2 sanidine (28.201 Ma) as the flux monitor and the irradiated material was distributed amongst the labs. Heizler was present during analysis at both OSU and UW and Jicha attended OSU during analysis. Physical presence was key towards gaining understanding of individual protocols and prompted valuable discussions. Analyses were carried out on single crystals using total fusion and/or step heating approaches. Age agreement was achieved within 2s uncertainty that ranged between (0.03-0.3%, 0.13-0.37% and 1.8-2.6%) for AC-2, BS and QIX, respectively. Each lab found AC-2 to vary somewhat beyond a normal distribution and to yield an age relative to FC-2 of ~1.185 Ma that is ~1.3% (~5-10 sigma) lower than some published estimates. A key cause of the variation between this study and previous results may be variable gas pressure equilibration times between extraction line and mass spectrometer coupled with variable choices to estimate time zero by other laboratories. The majority of our efforts concentrated on the QIX sanidine where prior data obtained by our labs revealed a factor of two spread in age (~11 and 23 ka) based on experiments carried out by total fusion and bulk incremental heating. By conducting single crystal age spectrum analysis we were able to mitigate effects of melt inclusion hosted excess argon and xenocrystic contamination towards obtaining analytical agreement with apparent ages near 10 ka. However, philosophical

  16. AR Signaling in Breast Cancer

    PubMed Central

    Rahim, Bilal; O’Regan, Ruth

    2017-01-01

    Androgen receptor (AR, a member of the steroid hormone receptor family) status has become increasingly important as both a prognostic marker and potential therapeutic target in breast cancer. AR is expressed in up to 90% of estrogen receptor (ER) positive breast cancer, and to a lesser degree, human epidermal growth factor 2 (HER2) amplified tumors. In the former, AR signaling has been correlated with a better prognosis given its inhibitory activity in estrogen dependent disease, though conversely has also been shown to increase resistance to anti-estrogen therapies such as tamoxifen. AR blockade can mitigate this resistance, and thus serves as a potential target in ER-positive breast cancer. In HER2 amplified breast cancer, studies are somewhat conflicting, though most show either no effect or are associated with poorer survival. Much of the available data on AR signaling is in triple-negative breast cancer (TNBC), which is an aggressive disease with inferior outcomes comparative to other breast cancer subtypes. At present, there are no approved targeted therapies in TNBC, making study of the AR signaling pathway compelling. Gene expression profiling studies have also identified a luminal androgen receptor (LAR) subtype that is dependent on AR signaling in TNBC. Regardless, there seems to be an association between AR expression and improved outcomes in TNBC. Despite lower pathologic complete response (pCR) rates with neoadjuvant therapy, patients with AR-expressing TNBC have been shown to have a better prognosis than those that are AR-negative. Clinical studies targeting AR have shown somewhat promising results. In this paper we review the literature on the biology of AR in breast cancer and its prognostic and predictive roles. We also present our thoughts on therapeutic strategies. PMID:28245550

  17. AR Signaling in Breast Cancer.

    PubMed

    Rahim, Bilal; O'Regan, Ruth

    2017-02-24

    Androgen receptor (AR, a member of the steroid hormone receptor family) status has become increasingly important as both a prognostic marker and potential therapeutic target in breast cancer. AR is expressed in up to 90% of estrogen receptor (ER) positive breast cancer, and to a lesser degree, human epidermal growth factor 2 (HER2) amplified tumors. In the former, AR signaling has been correlated with a better prognosis given its inhibitory activity in estrogen dependent disease, though conversely has also been shown to increase resistance to anti-estrogen therapies such as tamoxifen. AR blockade can mitigate this resistance, and thus serves as a potential target in ER-positive breast cancer. In HER2 amplified breast cancer, studies are somewhat conflicting, though most show either no effect or are associated with poorer survival. Much of the available data on AR signaling is in triple-negative breast cancer (TNBC), which is an aggressive disease with inferior outcomes comparative to other breast cancer subtypes. At present, there are no approved targeted therapies in TNBC, making study of the AR signaling pathway compelling. Gene expression profiling studies have also identified a luminal androgen receptor (LAR) subtype that is dependent on AR signaling in TNBC. Regardless, there seems to be an association between AR expression and improved outcomes in TNBC. Despite lower pathologic complete response (pCR) rates with neoadjuvant therapy, patients with AR-expressing TNBC have been shown to have a better prognosis than those that are AR-negative. Clinical studies targeting AR have shown somewhat promising results. In this paper we review the literature on the biology of AR in breast cancer and its prognostic and predictive roles. We also present our thoughts on therapeutic strategies.

  18. Geochemical characteristics and K-Ar ages of rare-metal bearing pegmatites from the Birimian of southeastern Ghana

    USGS Publications Warehouse

    Chalokwu, C.I.; Ghazi, M.A.; Foord, E.E.

    1997-01-01

    The pegmatite-aplite rocks at Mankwadzi (Ejisimanku Hills) in southeastern Ghana are part of the pegmatite district that extends from Cape Coast to Winneba along the Atlantic coastline. The pegmatites are associated with the Cape Coast granite complex and were intruded during the waning phase of the Eburnian Orogeny (???2.0 Ga). Three muscovite separates from pegmatite give K-Ar retention ages of 1909 ?? 13 Ma, 1965 ?? 13 Ma and 2019 ?? 14 Ma. A biotite separate from granite yields a K-Ar age of 1907 ?? 13 Ma. These ages are similar to K-Ar dates previously reported for the Cape Coast granites, indicating that the granites and pegmatites are coeval and probably genetically linked. The pegmatites are enriched in Li, Be, Nb and Sn and considerably impoverished in Rb, Th, Y and REEs. Microscopic examination of quartz from the pegmatites shows a large number of low salinity fluid inclusions that can be divided into two types: (1) one-phase liquid or gas-filled inclusions; and (2) two-phase liquid-vapour inclusions, with the vapour occupying 2-5% of the volume. The homogenisation temperature of the fluid inclusions clusters between 129 and 144??C. These homogenisation temperatures lead to an inferred entrapment temperature of ???300??C at a pressure of ???2.5 kbar, which is estimated for the metamorphism of host hornblende schists. The pegmatite fluid inclusions are interpreted as being secondary to the quartz hosts. ?? 1997 Elsevier Science Limited.

  19. Energy-filtered TEM imaging and EELS study of ODS particles and argon-filled cavities in ferritic-martensitic steels.

    PubMed

    Klimiankou, M; Lindau, R; Möslang, A

    2005-01-01

    Oxide-dispersion-strengthened (ODS) ferritic-martensitic steels with yttrium oxide (Y(2)O(3)) have been produced by mechanical alloying and hot isostatic pressing for use as advanced material in fusion power reactors. Argon gas, usually widely used as inert gas during mechanical alloying, was surprisingly detected in the nanodispersion-strengthened materials. Energy-filtered transmission electron microscopy (EFTEM) and electron energy loss spectroscopy (EELS) led to the following results: (i) chemical composition of ODS particles, (ii) voids with typical diameters of 1-6 nm are formed in the matrix, (iii) these voids are filled with Ar gas, and (iv) the high-density nanosized ODS particles serve as trapping centers for the Ar bubbles. The Ar L(3,2) energy loss edge at 245 eV as well as the absorption features of the ODS particle elements were identified in the EELS spectrum. The energy resolution in the EEL spectrum of about 1.0 eV allows to identify the electronic structure of the ODS particles.

  20. In-situ Ar isotope, 40Ar/39Ar analysis and mineral chemistry of nosean in the phonolite from Olbrück volcano, East Eifel volcanic field, Germany: Implication for the source of excess 40Ar

    NASA Astrophysics Data System (ADS)

    Sudo, Masafumi; Altenberger, Uwe; Günter, Christina

    2014-05-01

    Since the report by Lippolt et al. (1990), hauyne and nosean phenocrysts in certain phonolites from the northwest in the Quaternary East Eifel volcanic field in Germany were known to contain significant amounts of excess 40Ar, thus, show apparent older ages than the other minerals. However, its petrographic meaning have not been well known. Meanwhile, Sumino et al. (2008) has identified the source of the excess 40Ar in the plagioclase phenocrysts from the historic Unzen dacite lava as the melt inclusions in the zones parallely developed to the plagioclase rim by in-situ laser Ar isotope analysis. In order to obtain eruption ages of very young volcanoes as like Quaternary Eifel volcanic field by the K-Ar system, it is quite essential to know about the location of excess 40Ar in volcanic rocks. We have collected phonolites from the Olbrück volcano in East Eifel and investigated its petrography and mineral chemistry and also performed in-situ Ar isotope analyses of unirradiated rock section sample and also in-situ 40Ar/39Ar analysis of neutron irradiated section sample with the UV pulse laser (wavelength 266 nm) and 40Ar/39Ar analytical system of the University of Potsdam. Petrographically, nosean contained fine melt and/or gas inclusions of less than 5 micrometer, which mostly distribute linearly and are relatively enriched in chlorine than the areas without inclusions. Solid inclusions of similar sizes contain CaO and fluorine. In nosean, typically around 5 wt% of sulfur is contained. The 40Ar/39Ar dating was also performed to leucite, sanidine and groundmass in the same section for comparison of those ages with that of nosean. In each analysis, 200 micrometer of beam size was used for making a pit with depth of up to 300 micrometer by laser ablation. As our 40Ar/39Ar analyses were conducted one and half year after the neutron irradiation, thus, short lived 37Ar derived from Ca had decayed very much, we measured Ca and K contents in nosean by SEM-EDS then applied

  1. AR-39-AR-40 "Age" of Basaltic Shergottite NWA-3171

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Park, Jisun

    2007-01-01

    North-West-Africa 3171 is a 506 g, relatively fresh appearing, basaltic shergottite with similarities to Zagami and Shergotty, but not obviously paired with any of the other known African basaltic shergottites. Its exposure age has the range of 2.5-3.1 Myr , similar to those of Zagami and Shergotty. We made AR-39-AR-40 analyses of a "plagioclase" (now shock-converted to maskelynite) separate and of a glass hand-picked from a vein connected to shock melt pockets.. Plagioclase was separated using its low magnetic susceptibility and then heavy liquid with density of <2.85 g/cm(exp 3). The AR-39-AR-40 age spectrum of NWA-317 1 plag displays a rise in age over 20-100% of the 39Ar release, from 0.24 Gyr to 0.27 Gy.

  2. Computational phase diagrams of noble gas hydrates under pressure

    SciTech Connect

    Teeratchanan, Pattanasak Hermann, Andreas

    2015-10-21

    We present results from a first-principles study on the stability of noble gas-water compounds in the pressure range 0-100 kbar. Filled-ice structures based on the host water networks ice-I{sub h}, ice-I{sub c}, ice-II, and C{sub 0} interacting with guest species He, Ne, and Ar are investigated, using density functional theory (DFT) with four different exchange-correlation functionals that include dispersion effects to various degrees: the non-local density-based optPBE-van der Waals (vdW) and rPW86-vdW2 functionals, the semi-empirical D2 atom pair correction, and the semi-local PBE functional. In the He-water system, the sequence of stable phases closely matches that seen in the hydrogen hydrates, a guest species of comparable size. In the Ne-water system, we predict a novel hydrate structure based on the C{sub 0} water network to be stable or at least competitive at relatively low pressure. In the Ar-water system, as expected, no filled-ice phases are stable; however, a partially occupied Ar-C{sub 0} hydrate structure is metastable with respect to the constituents. The ability of the different DFT functionals to describe the weak host-guest interactions is analysed and compared to coupled cluster results on gas phase systems.

  3. Computational phase diagrams of noble gas hydrates under pressure

    NASA Astrophysics Data System (ADS)

    Teeratchanan, Pattanasak; Hermann, Andreas

    2015-10-01

    We present results from a first-principles study on the stability of noble gas-water compounds in the pressure range 0-100 kbar. Filled-ice structures based on the host water networks ice-Ih, ice-Ic, ice-II, and C0 interacting with guest species He, Ne, and Ar are investigated, using density functional theory (DFT) with four different exchange-correlation functionals that include dispersion effects to various degrees: the non-local density-based optPBE-van der Waals (vdW) and rPW86-vdW2 functionals, the semi-empirical D2 atom pair correction, and the semi-local PBE functional. In the He-water system, the sequence of stable phases closely matches that seen in the hydrogen hydrates, a guest species of comparable size. In the Ne-water system, we predict a novel hydrate structure based on the C0 water network to be stable or at least competitive at relatively low pressure. In the Ar-water system, as expected, no filled-ice phases are stable; however, a partially occupied Ar-C0 hydrate structure is metastable with respect to the constituents. The ability of the different DFT functionals to describe the weak host-guest interactions is analysed and compared to coupled cluster results on gas phase systems.

  4. The Congested-like Tracheae Gene of Drosophila Melanogaster Encodes a Member of the Mitochondrial Carrier Family Required for Gas-Filling of the Tracheal System and Expansion of the Wings after Eclosion

    PubMed Central

    Hartenstein, K.; Sinha, P.; Mishra, A.; Schenkel, H.; Torok, I.; Mechler, B. M.

    1997-01-01

    A recessive semi-lethal mutation resulting from the insertion of a P-lacW transposon at the cytological position 23A on the polytene chromosomes of Drosophila melanogaster was found to affect the unfolding and expansion of the wings resulting in a loss of venation and a marked decrease in their size. Lethality was polyphasic with numerous animals dying during early larval development and displaying apparently collapsed tracheal trees. The gene was therefore designated as congested-like tracheae, or colt. The colt mutation resulted from the insertion of a P-lacW transposon within the coding region of a 1.4-kb transcript. Wild-type function was restored by inducing a precise excision of the P-lacW transposon, while a deletion of the colt locus, produced by imprecise excision of the P element, showed a phenotype similar to that of the original P insert. The colt gene consists of a single exon and encodes a protein of 306 amino acids made of three tandem repeats, each characterized by two predicted transmembrane segments and a loop domain. The COLT protein shares extensive homology with proteins in the mitochondrial carrier family and particularly with the DIF-1 protein of Caenorhabditis elegans, which has been shown to be maternally required for embryonic tissue differentiation. Our analysis revealed that zygotic colt function is dispensable for normal embryonic morphogenesis but is required for gas-filling of the tracheal system at hatching time of the embryo and for normal epithelial morphogenesis of the wings. PMID:9409834

  5. Stationary afterglow measurements of the temperature dependence of the electron–ion recombination rate coefficients of {{\\rm{H}}}_{2}{{\\rm{D}}}^{+} and {{HD}}_{2}^{+} in He/Ar/H2/D2 gas mixtures at T = 80–145 K 

    NASA Astrophysics Data System (ADS)

    Plašil, Radek; Dohnal, Petr; Kálosi, Ábel; Roučka, Štěpán; Johnsen, Rainer; Glosík, Juraj

    2017-03-01

    We report measurements of the binary and ternary recombination rate coefficients of deuterated isotopologues of {{{H}}}3+. A cavity ring-down absorption spectrometer was used to monitor the fractional abundances of {{{H}}}3+, {{{H}}}2{{{D}}}+, {{HD}}2+ and {{{D}}}3+ during the decay of a plasma in He/Ar/{{{H}}}2/{{{D}}}2 mixtures. A dependence of the measured effective recombination rate coefficients on the helium buffer gas density was observed and hence both the binary and the ternary recombination rate coefficients for {{{H}}}2{{{D}}}+ and {{HD}}2+ were obtained in the temperature range 80–145 K.

  6. Highly charged Ar{sup q+} ions interacting with metals

    SciTech Connect

    Wang Jijin; Zhang Jian; Gu Jiangang; Luo Xianwen; Hu Bitao

    2009-12-15

    Using computer simulation, alternative methods of the interaction of highly charged ions Ar{sup q+} with metals (Au, Ag) are used and verified in the present work. Based on the classical over-barrier model, we discussed the promotion loss and peeling off processes. The simulated total potential electron yields agree well with the experiment data in incident energy ranging from 100 eV to 5 keV and all charge states of Ar{sup q+}. Based on the TRIM code, we obtain the side-feeding rate as well as the motion and charge transfer of HCI below the surface. Some results, including the array of KL{sup x} x-ray satellite lines, the respective contribution of autoionization, and side-feeding to inner shells, and the filling rates and lifetime of inner shells for Ar agree well with experiment or theory.

  7. Loose-fill insulations

    SciTech Connect

    1995-05-01

    Whether you are increasing the insulation levels in your current home or selecting insulation for a new home, choosing the right insulation material can be challenging. Fibrous loose-fill insulations such as cellulose, fiberglass, and rock wool are options you may wish to consider. This publication will introduce you to these materials--what they are, how they are applied, how they compare with each other, and other considerations regarding their use--so that you can decide whether loose fills are right for your home.

  8. Ar-40/Ar-39 dating, Ar diffusion properties, and cooling rate determinations of severely shocked chondrites

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Hirsch, W. C.

    1980-01-01

    The ages of Ar-40/Ar-39 chondrites were computed to be 4.29 to 1.0 Gyr, with degassing times of 0.5 to 1.0 Gyr. The values of the diffusion parameter for Ar in Arrhenius plots show linear relationships which correspond to the degassing of different mineral phases with distinct K/Ca ratios and different average temperatures for Ar release. The experimental values of the diffusion parameter for the high-temperature phase of severely shocked chondrites are 10 to the -7th to 10 to the -5th/s for the shock-heating temperatures in the 950-1200 C range; the inferred reheating temperatures and the fraction of the Ar-40 loss during the reheating event suggest post-shock cooling rates and burial depths of 0.01-0.0001 C/s and 0.5-2m, respectively.

  9. Determination of K-Ar ages in milligram samples using an infrared laser for argon extraction.

    PubMed

    Solé, Jesús

    2009-11-01

    The K-Ar dating method has been used for decades to decipher the ages of terrestrial and extraterrestrial minerals and rocks. The natural radioactive decay of a metal to a rare gas is an advantage that allows the determination of very small amounts of argon by mass spectrometry. Although the Ar-Ar method has superseded K-Ar, the latter is still used and it has room for improvement. One of these is the reduction of the analyzed sample mass, a desideratum of any current analytical technique. I report here our experience in K-Ar geochronology of milligram-sized samples using laser heating and melting for gas extraction. This modification of the classical K-Ar technique has not been, to my knowledge, used in any other laboratory in the world and deserves a detailed description of its advantages and limitations.

  10. Incremental Heating 40Ar/39Ar Analyses of Mono Basin Tephra

    NASA Astrophysics Data System (ADS)

    Deino, A.; Hemming, S. R.; Ali, G. A.; Zimmerman, S. R.; Turrin, B. D.

    2012-12-01

    The glacially and volcanically derived sediments of the Wilson Creek Formation (Lajoie, 1968), Mono Basin, eastern California, contain an invaluable archive of hydroclimatic, volcanic, and paleomagnetic events encompassing the past ~85 ka. Accurate radioisotopic dating of this sequence, however, has been stymied by systematic problems encountered in applying C-14, U/Th, and 40Ar/39Ar methods. 40Ar/39Ar dating of the 19-plus locally derived tephra horizons within the formation has been foiled by the presence of excess argon, incorporation of older crystal components and by the difficulty of accurately measuring of the age of late Quaternary materials (Chen et al., 1996; Kent et al., 2002; Cassata et al., 2011). We have acquired detailed laser step-heating 40Ar/39Ar age spectra on individual sanidine crystals of several Wilson Creek ashes using the multiple ion counter capability of the BGC Noblesse noble gas mass spectrometer. This approach represents a breakthrough for young materials, as it allows examination of the internal argon systematics of each grain and identification of steps representing excess Ar components as distinct from primary volcanic ages. Typically, anomalously old ages occur in the first 10-50% of the 39Ar release, followed by an age 'plateau' that is generally consistent from grain to grain. This methodological advance is a result of improvements in extraction-line design and mass spectrometer manufacture (in particular, improved source ionization efficiency, utilization of low-noise ion counters, and fully simultaneous data collection of all relevant isotopes). For example, 15 single-grain step-heating experiments (8-13 steps each) have been performed on sanidine from Ash 12. All crystals yielded apparent-age plateaus in the latter stages of the release, often preceded by anomalously old steps. While the age distribution of the plateau results are unimodal and consistent, with a weighted-mean age of 42.1 ± 0.3 ka (0.7% 1σ error), the

  11. Amplification properties of vacuum ultraviolet Ar2* produced by infrared high-intensity laser

    NASA Astrophysics Data System (ADS)

    Kaku, Masanori; Harano, Shinya; Matsumoto, Ryota; Katto, Masahito; Kubodera, Shoichi

    2011-07-01

    We report optical amplification of Ar2* at 126nm, pumped by optical-field-induced ionization (OFI) created by an infrared high-intensity laser. A gain--length product of 0.84 was obtained by using multipass amplification with a vacuum ultraviolet (VUV) cavity. The gain--length product was increased up to 4.3 through the use of single-pass amplification with a VUV reflector and a hollow 5.0cm-long fiber. Similar small signal gain coefficients of 0.84 and 0.86cm-1 were obtained in two different experiments, in which OFI Ar plasma gain media were produced in free space filled with Ar and inside an Ar-filled hollow fiber.

  12. ARS-Media for excel instruction manual

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ARS-Media for Excel Instruction Manual is the instruction manual that explains how to use the Excel spreadsheet ARS-Media for Excel application. ARS-Media for Excel Instruction Manual is provided as a pdf file....

  13. Experimental M1 Transition Rates of Coronal Lines from AR X, AR XIV, and AR XV

    NASA Astrophysics Data System (ADS)

    Träbert, E.; Beiersdorfer, P.; Utter, S. B.; Brown, G. V.; Chen, H.; Harris, C. L.; Neill, P. A.; Savin, D. W.; Smith, A. J.

    2000-09-01

    Transition probabilities of three magnetic dipole (M1) transitions in multiply charged ions of Ar have been measured using the Livermore electron-beam ion trap. Two of the transitions are in the ground configurations of Ar XIV (B-like) and Ar IX (F-like), and are associated with the coronal lines at 4412.4 and 5533.4 Å, respectively. The third is in the excited 2s2p configuration of Be-like Ar XV and produces the coronal line at 5943.73 Å. Our results for the three atomic level lifetimes are 9.32+/-0.12 ms for the Ar X 2s22p5 2Po1/2 level, 9.70+/-0.15 ms for the Ar XIV 2s22p 2Po3/2 level, and 15.0+/-0.8 ms for the Ar XV 2s2p 3Po2 level. These results differ significantly from earlier measurements and are the most accurate ones to date.

  14. Atmospheric Pressure Plasma Jet in Ar and O2/Ar Mixtures: Properties and High Performance for Surface Cleaning

    NASA Astrophysics Data System (ADS)

    Jin, Ying; Ren, Chunsheng; Yang, Liang; Zhang, Jialiang; Wang, Dezhen

    2013-12-01

    An atmospheric pressure plasma jet generated in Ar and O2/Ar mixtures has been investigated by specially designed equipment with double power electrodes at 20~32 kHz, and their effects on the cleaning of surfaces have been studied. Properties of the jet discharge are studied by electrical diagnostics, including the waveform of discharge voltage, discharge current and the Q-V Lissajous figures. The optical emission spectroscopy is used to measure the plasma parameters, such as the excitation temperature and the gas temperature. It is found that the consumed power and the excitation temperature increase with increase of the discharge frequency. On the other hand, at the same discharge frequency, these parameters in O2/Ar mixture plasma are found to be much larger. The effect on surface cleaning is studied from the changes in the contact angle. For Ar plasma jet, the contact angle decreases with increase of the discharge frequency. For O2/Ar mixture plasma jet, the contact angle decreases with increase of discharge frequency up to 26 kHz, however, further increase of discharge frequency does not show further decrease in the contact angle. At the same discharge frequency, the contact angle after O2/Ar mixture plasma cleaning is found to be much lower compared to the case of pure Ar. From the results of quadrupole mass-spectrum analysis, we can identify more fragment molecules of CO and H2O in the emitted gases after O2/Ar plasma jet treatment compared with Ar plasma jet treatment, which are produced by the decomposition of surface organic contaminants during the cleaning process.

  15. 40Ar/39Ar dating of tourmaline as a tool for high-temperature metamorphism thermochronology

    NASA Astrophysics Data System (ADS)

    Jourdan, Fred; Thern, Eric

    2014-05-01

    Tourmaline is an ubiquitous mineral, with properties making it ideal for studying metamorphic processes as well as a useful tool for a wide range of applications (e.g, magmatism, metasomatism, ore deposits [1]), mostly because it is not sensitive to chemical or mechanical alteration and is stable over a wide range of pressure-temperature conditions (up to 6 GPa and 850° C [2]). Typical metamorphic tourmaline types include dravite and shorl which, along with elbaite, belong to the alkali group [1]. The alkali group is notable because tourmalines from this group tend to incorporate trace amounts of K2O and therefore, can be dated using the 40Ar/39Ar technique. In order to understand the maximum temperature below which the K/Ar chronometer stays closed to argon loss by thermally activated diffusion, we carried out temperature controlled furnace diffusion experiments on well-behaved 40Ar/39Ar plateau-forming Archean tourmaline of 2935 ± 9 Ma [3]. Each experiment yielded an Arrhenius profile (Do vs. 1/temperature) that shows that the 39Ar data form two linear arrays with two distinct slopes. The first array only includes a few % of the total gas, has a shallow slope and shows very fast diffusivity at low temperature. We interpret these data as indicating very fast release of argon by cracks and defects. The second array of data points includes most of the gas of each experiment and forms a much steeper slope. These data yielded Ea (activation energy) values ranging from 120 to 157 Kcal/mol and D0 (pre-exponential diffusion factor) values ranging from 1.9x106 to 2.5x109 cm2/s for crystals with an average radius of 100 ± 25 μm. Three additional experiments using a laser (resulting in poor temperature control) suggest similar values although the latter experiments are considered semi-quantitative. The furnace experiments suggest that tourmaline has a weighted mean closure temperature of 804 ± 90 ° C (1σ) for a cooling rate of 10° C/Ma. Monte Carlo simulations using

  16. Natural ³⁷Ar concentrations in soil air: implications for monitoring underground nuclear explosions.

    PubMed

    Riedmann, Robin A; Purtschert, Roland

    2011-10-15

    For on-site inspections (OSI) under the Comprehensive Nuclear-Test-Ban Treaty (CTBT) measurement of the noble gas ³⁷Ar is considered an important technique. ³⁷Ar is produced underground by neutron activation of Calcium by the reaction ⁴⁰Ca(n,α)³⁷Ar. The naturally occurring equilibrium ³⁷Ar concentration balance in soil air is a function of an exponentially decreasing production rate from cosmic ray neutrons with increasing soil depth, diffusive transport in the soil air, and radioactive decay (T(1/2): 35 days). In this paper for the first time, measurements of natural ³⁷Ar activities in soil air are presented. The highest activities of ~100 mBq m⁻³ air are 2 orders of magnitude larger than in the atmosphere and are found in 1.5-2.5 m depth. At depths > 8 m ³⁷Ar activities are < 20 mBq m⁻³ air. After identifying the main ³⁷Ar production and gas transport factors the expected global activity range distribution of ³⁷Ar in shallow subsoil (0.7 m below the surface) was estimated. In high altitude soils, with large amounts of Calcium and with low gas permeability, ³⁷Ar activities may reach values up to 1 Bq m⁻³.

  17. Unmixing 40Ar/39Ar Muscovite Ages Using Powder X-ray Diffraction

    NASA Astrophysics Data System (ADS)

    McAleer, R. J.; Kunk, M. J.; Valley, P. M.; Walsh, G. J.; Bish, D. L.; Wintsch, R. P.

    2014-12-01

    Whole rock powder X-ray diffraction (XRD) experiments from eight samples collected across a retrograde ductile shear zone in the Devonian Littleton Formation near Claremont, NH, exhibit broad and asymmetric to bimodal muscovite 00l reflections. These composite 00l reflections exhibit a systematic change in shape with increasing retrograde strain. Microtextural relationships, electron microprobe quantitative analyses, and element mapping indicate that the change in peak shape reflects progressive dissolution of metastable Na-rich muscovite and the precipitation of stable Na-poor muscovite. 40Ar/39Ar step heating experiments on muscovite concentrates from these samples show a decrease in total gas age from 274 to 258 Ma as the highest strain zone is approached, and steps within individual spectra range in age by ~20 m.y. The correlation between age and 00l peak shape suggests that the argon isotopic system also tracks the dissolution-precipitation process. Furthermore, the variation in age during step heating indicates that these populations exhibit different in-vacuo degassing behavior. Comparison of whole rock and muscovite concentrate XRD patterns from the same samples shows that the mineral separation process can fractionate these muscovite populations. With this knowledge, four muscovite concentrates were prepared from a single hand sample, analyzed by XRD, and dated. Combining modal estimates from XRD experiments with total gas ages, the four splits narrowly define a mixing line that resolves end-member ages of 250 and 300 Ma for the neocrystallized and earlier high grade populations of muscovite, respectively. These ages are consistent with age data from all other samples. The results show that, in some settings, powder XRD provides a powerful and time effective method to both identify the existence of and establish the proportions of multiple compositional populations of muscovite prior to 40Ar/39Ar analysis. This approach will be especially useful in

  18. The structure, properties, and nature of HArF-benzene complex: redshift and blueshift of Ar-H stretch frequency and rare gas atomic number dependence of hydrogen bonds.

    PubMed

    Liu, Xiaofeng; Li, Qingzhong; Li, Ran; Li, Wenzuo; Cheng, Jianbo

    2011-12-15

    Ab initio calculations have been performed for the complexes of benzene with HArF, HKrF, and HXeF. The computed results indicate that the complexes of benzene-HArF exist in different conformations and among them those with π-hydrogen bonds are the more stable than those with C-H···F hydrogen bonds. Interestingly, the Ar-H stretching frequency is redshifted in the more stable isomer and blueshifted in the less stable form. The Ng (Ng=Ar, Kr, and Xe) atomic number dependence of the Ng-H···π and C-H···F hydrogen bonds has been explored. The result indicates that the strength of Ng-H···π and C-H···F hydrogen bonds is weakened with the increase of Ng atomic number. Natural bond orbital analysis has been performed to understand the interaction nature, frequency shift of H-Ng stretch, and dependence of Ng-H···π and C-H···F hydrogen bonds on the Ng atomic number.

  19. Ar-39-Ar-40 Ages of Two Nakhlites, MIL03346 and Y000593: A Detailed Analysis

    NASA Technical Reports Server (NTRS)

    Park, Jisun; Garrison, Daniel; Bogard, Donald

    2007-01-01

    Radiometric dating of martian nakhlites by several techniques have given similar ages of approx.1.2-1.4 Ga [e.g. 1, 2]. Unlike the case with shergottites, where the presence of martian atmosphere and inherited radiogenic Ar-40 produce apparent Ar-39-Ar-40 ages older than other radiometric ages, Ar-Ar ages of nakhlites are similar to ages derived by other techniques. However, even in some nakhlites the presence of trapped martian Ar produces some uncertainty in the Ar-Ar age. We present here an analysis of such Ar-Ar ages from the MIL03346 and Y000593 nakhlites.

  20. An Astronomically Dated Standard in 40Ar/39Ar Geochronology?

    NASA Astrophysics Data System (ADS)

    Kuiper, K.; Hilgen, F.; Krijgsman, W.; Wijbrans, J.

    2003-12-01

    The standard geological time scale of Berggren et al. (1995) and Cande and Kent (1995) is calibrated with different absolute dating techniques, i.e. the Plio - Pleistocene relies on astronomical tuning, and older parts of the time scale are based on radio-isotopic (40Ar/39Ar and U/Pb) calibration methods. In the new edition of the standard geological timescale (Lourens et al., to be published in 2004) the entire Neogene will rely on astronomical dating. Therefore, it is of crucial importance that all dating methods produce equivalent absolute ages when the same geological event is dated. The Mediterranean Neogene provides an excellent opportunity to compare different dating methods by isotopic dating (40Ar/39Ar, U/Pb) of volcanic ash layers intercalated in astronomically dated sediments. Here we will show that in spite of potential errors in all methods, we succeeded to intercalibrate the 40Ar/39Ar and astronomical methods, arriving at astronomically calibrated age of 28.24 +/- 0.01 Ma for the in 40Ar/39Ar geochronology commonly used standard FCT sanidine. The advantage of an astronomically calibrated FCT above a K/Ar calibrated standard is a smaller error in the absolute age due to the lack of uncertainties related to 40K and radiogenic 40Ar contents in the primary standard and a decreasing influence of errors in the decay constant (branching ratio is not required). In addition to an astronomically calibrated FCT age we propose to introduce an astronomically dated standard. A direct astronomically dated standard can be regarded as a "primary" standard and does not require intercalibration with other standards, thus reducing analytical (and geological) uncertainties. Ash layers intercalated in sedimentary sequences in the Melilla Basin, Morocco appear to be the most suitable for this purpose. A reliable astronomical time control is available and intercalated ash layers contain sanidine phenocrysts up to 2 mm. Four ash layers are not or barely affected by

  1. Dye filled security seal

    DOEpatents

    Wilson, Dennis C. W.

    1982-04-27

    A security seal for providing an indication of unauthorized access to a sealed object includes an elongate member to be entwined in the object such that access is denied unless the member is removed. The elongate member has a hollow, pressurizable chamber extending throughout its length that is filled with a permanent dye under greater than atmospheric pressure. Attempts to cut the member and weld it together are revealed when dye flows through a rupture in the chamber wall and stains the outside surface of the member.

  2. Fluid Dynamics of Bottle Filling

    NASA Astrophysics Data System (ADS)

    McGough, Patrick; Gao, Haijing; Appathurai, Santosh; Basaran, Osman

    2011-11-01

    Filling of bottles is a widely practiced operation in a large number of industries. Well known examples include filling of ``large'' bottles with shampoos and cleaners in the household products and beauty care industries and filling of ``small'' bottles in the pharmaceutical industry. Some bottle filling operations have recently drawn much attention from the fluid mechanics community because of the occurrence of a multitude of complex flow regimes, transitions, and instabilities such as mounding and coiling that occur as a bottle is filled with a fluid. In this talk, we present a primarily computational study of the fluid dynamical challenges that can arise during the rapid filling of bottles. Given the diversity of fluids used in filling applications, we consider four representative classes of fluids that exhibit Newtonian, shear-thinning, viscoelastic, and yield-stress rheologies. The equations governing the dynamics of bottle filling are solved either in their full 3D but axisymmetric form or using the slender-jet approximation.

  3. Adsorption of Ar on a nonuniform MgO surface

    NASA Technical Reports Server (NTRS)

    Hinman, D. C.; Halsey, G. D.

    1976-01-01

    Data are presented for the adsorption of Ar and N2 on a strongly heterogeneous MgO surface at 84 K and for Ar at a range of temperatures between 130 and 250 K. The high-temperature data are analyzed according to a model which separates the contributions to the potential into bulk and surface terms, providing a method for the determination of the surface area from parameters characteristic of the bulk material. A solid-gas energy parameter and parameters indicating the strength of the impurity sites are also evaluated.

  4. Dusty Plasma in He-Ar Glow Discharge

    SciTech Connect

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

    2008-09-07

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

  5. Neon reduction program on Cymer ArF light sources

    NASA Astrophysics Data System (ADS)

    Kanawade, Dinesh; Roman, Yzzer; Cacouris, Ted; Thornes, Josh; O'Brien, Kevin

    2016-03-01

    In response to significant neon supply constraints, Cymer has responded with a multi-part plan to support its customers. Cymer's primary objective is to ensure that reliable system performance is maintained while minimizing gas consumption. Gas algorithms were optimized to ensure stable performance across all operating conditions. The Cymer neon support plan contains four elements: 1. Gas reduction program to reduce neon by >50% while maintaining existing performance levels and availability; 2. short-term containment solutions for immediate relief. 3. qualification of additional gas suppliers; and 4. long-term recycling/reclaim opportunity. The Cymer neon reduction program has shown excellent results as demonstrated through the comparison on standard gas use versus the new >50% reduced neon performance for ArF immersion light sources. Testing included stressful conditions such as repetition rate, duty cycle and energy target changes. No performance degradation has been observed over typical gas lives.

  6. Ar-39/Ar-40 systematics of Allende inclusions

    NASA Technical Reports Server (NTRS)

    Herzog, G. F.; Bence, A. E.; Bender, J.; Eichhorn, G.; Maluski, H.; Schaeffer, O. A.

    1980-01-01

    A laser microprobe was used to measure the Ar isotopic contents of individual mineral grains in four neutron-irradiated Allende samples: two coarse-grained Ca-Al-rich inclusions; one fine-grained Ca-Al-rich inclusion; and one sample with matrix and miscellaneous chondrules. The following K-Ar ages (G.y.) were obtained after degassing low Ar retentive sites by preheating the samples for one hour at 675 C: matrix, 3.5 + or - 0.2; three miscellaneous chondrules, 4.4 + or - 0.1, 4.0 + or - 0.1, and 4.4 + or - 0.1; and the fine-grained inclusion, 4.5 + or - 0.2. The minerals in the coarse-grained Ca-Al-rich inclusions have ubiquitous chlorine, less than 10 ppm K and apparent ages ranging upwards from 4.6 G.y. to well over 10 G.y. Possible explanations for these apparent ages are atmospheric contamination, the decay of K-40 prior to the formation of the solar system, and the trapping of radiogenic Ar-40 lost by the matrix.

  7. Variable leak gas source

    DOEpatents

    Henderson, Timothy M.; Wuttke, Gilbert H.

    1977-01-01

    A variable leak gas source and a method for obtaining the same which includes filling a quantity of hollow glass micro-spheres with a gas, storing said quantity in a confined chamber having a controllable outlet, heating said chamber above room temperature, and controlling the temperature of said chamber to control the quantity of gas passing out of said controllable outlet. Individual gas filled spheres may be utilized for calibration purposes by breaking a sphere having a known quantity of a known gas to calibrate a gas detection apparatus.

  8. Investigation of metastable production in a closed-cell dielectric capillary variable pressure He plasma jet with Ar admixture

    NASA Astrophysics Data System (ADS)

    Sands, Brian; Ganguly, Biswa

    2011-10-01

    For plasma processing applications of streamer-like atmospheric pressure plasma jets generated in a dielectric capillary, we have demonstrated that an admixture of Ar to the He gas flow greatly increases the lifetime of energetic species in the core flow through enhanced afterglow production of Ar 1s5 metastable species. To study this effect in more detail, we have used a closed-cell plasma jet that allows control over the background gas pressure and composition. We used a 20 ns risetime positive unipolar voltage pulse for excitation. A He flow with a 0-30% Ar admixture was studied using time-resolved emission and tunable diode laser absorption spectroscopy of the Ar 1s5 and He 23S metastable states. Nitrogen was used as the background gas. In pure He and pure Ar gases the He and Ar metastables respectively are produced in the first ~100 ns only in the active discharge. With Ar added to the He gas flow, He metastables produced in the active discharge are quickly quenched via Penning ionization of Ar while Ar 1s5 is enhanced over 1-2 μs in the afterglow, increasing the number density as high as 1013/cc and extending the effective lifetime up to 10 μs. This implies that He heavy particle kinetics are a key driver of enhanced afterglow plasma chemistry in plasma jets with rare gas mixtures.

  9. Space-filling percolation

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhijit; Manna, S. S.

    2014-03-01

    A region of two-dimensional space has been filled randomly with a large number of growing circular disks allowing only a "slight" overlapping among them just before their growth stops. More specifically, each disk grows from a nucleation center that is selected at a random location within the uncovered region. The growth rate δ is a continuously tunable parameter of the problem which assumes a specific value while a particular pattern of disks is generated. When a growing disk overlaps for the first time with at least one other disk, its growth is stopped and is said to be frozen. In this paper we study the percolation properties of the set of frozen disks. Using numerical simulations we present evidence for the following: (i) The order parameter appears to jump discontinuously at a certain critical value of the area coverage; (ii) the width of the window of the area coverage needed to observe a macroscopic jump in the order parameter tends to vanish as δ →0; and on the contrary (iii) the cluster size distribution has a power-law-decaying functional form. While the first two results are the signatures of a discontinuous transition, the third result is indicative of a continuous transition. Therefore we refer to this transition as a sharp but continuous transition similar to what has been observed in the recently introduced Achlioptas process of explosive percolation. It is also observed that in the limit of δ →0, the critical area coverage at the transition point tends to unity, implying that the limiting pattern is space filling. In this limit, the fractal dimension of the pore space at the percolation point has been estimated to be 1.42(10) and the contact network of the disk assembly is found to be a scale-free network.

  10. 39Ar-40Ar "ages" and origin of excess 40Ar in Martian shergottites

    NASA Astrophysics Data System (ADS)

    Bogard, Donald; Park, Jisun; Garrison, Daniel

    2009-06-01

    We report new 39Ar-40Ar measurements on 15 plagioclase, pyroxene, and/or whole rock samples of 8 Martian shergottites. All age spectra suggest ages older than the meteorite formation ages, as defined by Sm-Nd and Rb-Sr isochrons. Employing isochron plots, only Los Angeles plagioclase and possibly Northwest Africa (NWA) 3171 plagioclase give ages in agreement with their formation ages. Isochrons for all shergottite samples reveal the presence of trapped Martian 40Ar (40Arxs), which exists in variable amounts in different lattice locations. Some 40Arxs is uniformly distributed throughout the lattice, resulting in a positive isochron intercept, and other 40Arxs occurs in association with K-bearing minerals and increases the isochron slope. These samples demonstrate situations where linear Ar isochrons give false ages that are too old. After subtracting 40Ar*that would accumulate by 40K decay since meteorite formation and small amounts of terrestrial 40Ar, all young age samples give similar 40Arxs concentrations of ˜1-2 × 10-6cm3/g, but a variation in K content by a factor of ˜80. Previously reported NASA Johnson Space Center data for Zagami, Shergotty, Yamato (Y-) 000097, Y-793605, and Queen Alexandra Range (QUE) 94201 shergottites show similar concentrations of 40Arxs to the new meteorite data reported here. Similar 40Arxs in different minerals and meteorites cannot be explained as arising from Martian atmosphere carried in strongly shocked phases such as melt veins. We invoke the explanation given by Bogard and Park (2008) for Zagami, that this 40Arxs in shergottites was acquired from the magma. Similarity in 40Arxs among shergottites may reveal common magma sources and/or similar magma generation and emplacement processes.

  11. The ArDM Experiment

    NASA Astrophysics Data System (ADS)

    Bueno, A.; Ardm Collaboration

    2007-08-01

    We describe the Argon Dark Matter (ArDM) experiment. It consists on a one-ton liquid argon detector able to read independently ionization charge and scintillation light. This device has been optimized to perform a direct search for Weakly Interacting Massive Particles (WIMPs).

  12. ARS-Media for Excel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ARS-Media for Excel is an ion solution calculator that uses Microsoft Excel to generate recipes of salts for complex ion mixtures specified by the user. Generating salt combinations (recipes) that result in pre-specified target ion values is a linear programming problem. Thus, the recipes are genera...

  13. USDA-ARS Quartlerly News

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This quarterly article is an update of research going on at The USDA-ARS Thad Cochran Southern Horticultural Laboratory in Poplarville, MS to be published in the Louisiana Nursery and Landscape Associations (LANLA) quarterly newsletter. This is one of three publications that I am sending out to the ...

  14. High quality boron-doped epitaxial layers grown at 200°C from SiF4/H2/Ar gas mixtures for emitter formation in crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Léal, Ronan; Haddad, Farah; Poulain, Gilles; Maurice, Jean-Luc; Roca i Cabarrocas, Pere

    2017-02-01

    Controlling the doping profile in solar cells emitter and front/back surface field is mandatory to reach high efficiencies. In the current state of the art, these doped layers are made by dopant diffusion at around 900°C, which implies potential temperature induced damages in the c-Si absorber and for which a precise control of doping is difficult. An alternative solution based on boron-doped epitaxial silicon layers grown by plasma-enhanced chemical vapor deposition (PECVD) from 200°C using SiF4/H2/Ar/B2H6 chemistry is reported. The structural properties of the doped and undoped epitaxial layers were assessed by spectroscopic ellipsometry (SE), high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD). The incorporation of boron has been studied via plasma profiling time of flight mass spectrometry (PP-TOFMS) and secondary ion mass spectrometry (SIMS) measurements. The boron-doped epitaxial layers revealed excellent structural and electrical properties even for high carrier concentrations (>1019cm-3). Sheet resistances between 100 and 130 Ω/sq can been obtained depending on the thickness and the doping concentration, which is within the range of targeted values for emitters in c-Si solar cells. Electrochemical capacitance voltage (ECV) revealed a uniform doping profile around 3.1019 cm-3 and by comparing with SIMS measurement a doping efficiency around 50% has been found.

  15. Late Paleozoic deformation and exhumation in the Sierras Pampeanas (Argentina): 40Ar/39Ar-feldspar dating constraints

    NASA Astrophysics Data System (ADS)

    Löbens, Stefan; Oriolo, Sebastián; Benowitz, Jeff; Wemmer, Klaus; Layer, Paul; Siegesmund, Siegfried

    2016-09-01

    Systematic 40Ar/39Ar feldspar data obtained from the Sierras Pampeanas are presented, filling the gap between available high- (>~300 °C) and low-temperature (<~150 °C) thermochronological data. Results show Silurian-Devonian exhumation related to the late stages of the Famatinian/Ocloyic Orogeny for the Sierra de Pocho and the Sierra de Pie de Palo regions, whereas the Sierras de San Luis and the Sierra de Comechingones regions record exhumation during the Carboniferous. Comparison between new and available data points to a Carboniferous tectonic event in the Sierras Pampeanas, which represents a key period to constrain the early evolution of the proto-Andean margin of Gondwana. This event was probably transtensional and played a major role during the evolution of the Paganzo Basin as well as during the emplacement of alkaline magmatism in the retroarc.

  16. Lava-Filled Craters

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 12 June 2003

    Craters and hills form high standing streamlined plateaus or islands in a channeled area. The plateaus are rounded in the upstream direction and taper to a point in the downstream direction, indicating that the direction of flow in this area was roughly south to north, or bottom to top. The channels appear to be filled with lava flow deposits that are raised above the channel in some areas. A lava flow diverges around a small streamlined hill near the bottom of the image and then merges again around the northern end of it. Near the top of the image is a crater with a breach on the east (right) side that allowed the lava to flow in, leaving a lobate, high standing deposit. The channels may have been formed by the lava flows that currently fill them or there may have been flow of liquid water that created them before the lava was emplaced.

    Image information: VIS instrument. Latitude 16, Longitude 183 East (177 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built

  17. Armenian Astronomical Society (ArAS) activities

    NASA Astrophysics Data System (ADS)

    Mickaelian, A. M.

    2016-09-01

    A review on the activities and achievements of Armenian Astronomical Society (ArAS) and Armenian astronomy in general during the last years is given. ArAS membership, ArAS electronic newsletters (ArASNews), ArAS webpage, Annual Meetings, Annual Prize for Young Astronomers (Yervant Terzian Prize) and other awards, international relations, presence in international organizations, local and international summer schools, science camps, astronomical Olympiads and other events, matters related to astronomical education, astronomical heritage, amateur astronomy, astronomy outreach and ArAS further projects are described and discussed.

  18. Temperature-dependent gas transport performance of vertically aligned carbon nanotube/parylene composite membranes.

    PubMed

    Zhang, Lei; Yang, Junhe; Wang, Xianying; Zhao, Bin; Zheng, Guangping

    2014-01-01

    A novel composite membrane consisting of vertically aligned carbon nanotubes (CNTs) and parylene was successfully fabricated. Seamless filling of the spaces in CNT forests with parylene was achieved by a low-pressure chemical vapor deposition (CVD) technique and followed with the Ar/O2 plasma etching to expose CNT tips. Transport properties of various gases through the CNT/parylene membranes were explored. And gas permeances were independent on feed pressure in accordance with the Knudsen model, but the permeance values were over 60 times higher than that predicted by the Knudsen diffusion kinetics, which was attributed to specular momentum reflection inside smooth CNT pores. Gas permeances and enhancement factors over the Knudsen model firstly increased and then decreased with rising temperature, which confirmed the existence of non-Knudsen transport. And surface adsorption diffusion could affect the gas permeance at relatively low temperature. The gas permeance of the CNT/parylene composite membrane could be improved by optimizing operating temperature.

  19. Oldest human footprints dated by Ar/Ar

    NASA Astrophysics Data System (ADS)

    Scaillet, Stéphane; Vita-Scaillet, Grazia; Guillou, Hervé

    2008-11-01

    Fossilized human trackways are extremely rare in the geologic record. These bear indirect but invaluable testimony of human/hominid locomotion in open air settings and can provide critical information on biomechanical changes relating to bipedalism evolution throughout the primitive human lineage. Among these, the "Devil's footsteps" represent one of the best preserved human footprints suite recovered so far in a Pleistocene volcanic ash of the Roccamonfina volcano (southern Italy). Until recently, the age of these footprints remained speculative and indirectly correlated with a loosely dated caldera-forming eruption that produced the Brown Leucitic Tuff. Despite extensive hydrothermal alteration of the pyroclastic deposit and variable contamination with excess 40Ar, detailed and selective 40Ar/ 39Ar laser probe analysis of single leucite crystals recovered from the ash deposit shows that the pyroclastic layer and the footprints are 345 ± 6 kyr old (1 σ), confirming for the first time that these are the oldest human trackways ever dated, and that they were presumably left by the modern human predecessor, Homo heidelbergensis, close to Climatic Termination IV.

  20. Use of 41Ar production to measure ablator areal density in NIF beryllium implosions

    NASA Astrophysics Data System (ADS)

    Wilson, D. C.; Cassata, W. B.; Sepke, S. M.; Velsko, C. A.; Huang, H.; Yeamans, C. B.; Kline, J. L.; Yi, A.; Simakov, A. N.; Haan, S. W.; Batha, S. H.; Dewald, E. L.; Rygg, J. R.; Tommasini, R.; Xu, H.; Kong, C.; Bae, J.; Rice, N.

    2017-02-01

    For the first time, 41Ar produced by the (n,ϒ) reaction from 40Ar in the beryllium shell of a DT filled Inertial Confinement Fusion capsule has been measured. Ar is co-deposited with beryllium in the sputter deposition of the capsule shell. Combined with a measurement of the neutron yield, the radioactive 41Ar then quantifies the areal density of beryllium during the DT neutron production. The measured 1.15 ± 0.17 × 10+8 atoms of 41Ar are 2.5 times that from the best post-shot calculation, suggesting that the Ar and Be areal densities are correspondingly higher than those calculated. Possible explanations are that (1) the beryllium shell is compressed more than calculated, (2) beryllium has mixed into the cold DT ice, or more likely (3) less beryllium is ablated than calculated. Since only one DT filled beryllium capsule has been fielded at NIF, these results can be confirmed and expanded in the future.

  1. AR-39Ar-40 dating of basalts and rock breccias from Apollo 17 and the malvern achondrite

    NASA Technical Reports Server (NTRS)

    Kirsten, T.; Horn, P.

    1977-01-01

    The principles and the potential of the Ar-39/Ar-40 dating technique are illustrated by means of results obtained for 12 Apollo 17 rocks. Emphasis is given to methodical problems and the geological interpretation of lunar rock ages. Often it is ambigious to associate a given lunar breccia with a certain formation, or a formation with a basin. In addition, large-scale events on the Moon have not necessarily reset radiometric clocks completely. One rock fragment has a well-defined plateau age of 4.28 b.y., but the ages of two Apollo 17 breccias define an upper limit for the formation age of the Serenitatis basin at 4.05 b.y. Ages derived from five mare basalts indicate cessation of mare volcanism at Taurus-Littrow approximately 3.78 b.y. ago. Ca/Ar-37 exposure ages show that Camelot Crater was formed by an impact approximately 95 m.y. ago. After a short summary of the lunar timetable as it stands at the end of the Apollo program, we report about Ar-39/Ar-40 and rare gas studies on the Malvern meteorite. This achondrite resembles lunar highland breccias in texture as well as in rare-gas patterns. It was strongly annealed at some time between 3.4 and 3.8 b.y. ago. The results indicate that very similar processes have occurred on the Moon and on achondritic parent bodies at comparable times, leading to impact breccias with strikingly similar features, including the retention of rare-gas isotopes from various sources.

  2. Intermittent Surface Water Connectivity: Fill and Spill vs. Fill ...

    EPA Pesticide Factsheets

    Intermittent surface connectivity can influence aquatic systems, since chemical and biotic movements are often associated with water flow. Although often referred to as fill and spill, wetlands also fill and merge. We examined the effects of these connection types on water levels, ion concentrations, and biotic communities of eight prairie pothole wetlands between 1979 and 2015. Fill and spill caused pulsed surface water connections that were limited to periods following spring snow melt. In contrast, two wetlands connected through fill and merge experienced a nearly continuous, 20-year surface water connection and had completely coincident water levels. Fill and spill led to minimal convergence in dissolved ions and macroinvertebrate composition, while these constituents converged under fill and merge. The primary factor determining difference in responses was duration of the surface water connection between wetland pairs. Our findings suggest that investigations into the effects of intermittent surface water connections should not consider these connections generically, but need to address the specific types of connections. In particular, fill and spill promotes external water exports while fill and merge favors internal storage. The behaviors of such intermittent connections will likely be accentuated under a future with more frequent and severe climate extremes. Under the Safe and Sustainable Water Resources National Program, work is being done to qu

  3. A path-integral Monte Carlo study of a small cluster: The Ar trimer

    NASA Astrophysics Data System (ADS)

    Pérez de Tudela, R.; Márquez-Mijares, M.; González-Lezana, T.; Roncero, O.; Miret-Artés, S.; Delgado-Barrio, G.; Villarreal, P.

    2010-06-01

    The Ar3 system has been studied between T =0 K and T =40 K by means of a path-integral Monte Carlo (PIMC) method. The behavior of the average energy in terms of the temperature has been explained by comparison with results obtained with the thermal averaged rovibrational spectra estimated via: (i) a quantum mechanical method based on distributed Gaussian functions for the interparticle distances and (ii) an analytical model which precisely accounts for the participation of the dissociative continua Ar2+Ar and Ar+Ar+Ar. Beyond T ˜20 K, the system explores floppier configurations than the rigid equilateral geometry, as linear and Ar-Ar2-like arrangements, and fragmentates around T ˜40 K. A careful investigation of the specific heat in terms of a confining radius in the PIMC calculation seems to discard a proper phase transition as in larger clusters, in apparent contradiction with previous reports of precise values for a liquid-gas transition. The onset of this noticeable change in the dynamics of the trimer occurs, however, at a remarkably low value of the temperature in comparison with Arn systems formed with more Ar atoms. Quantum mechanical effects are found of relevance at T ≤15 K, with both energies and radial distributions obtained with a quantum PIMC deviating from the corresponding classical results, thus precluding exclusively classical approaches for a precise description of the system at this low temperature range.

  4. Atmospheric Ar and Ne returned from mantle depths to the Earth's surface by forearc recycling.

    PubMed

    Baldwin, Suzanne L; Das, J P

    2015-11-17

    In subduction zones, sediments, hydrothermally altered lithosphere, fluids, and atmospheric gases are transported into the mantle, where ultrahigh-pressure (UHP) metamorphism takes place. However, the extent to which atmospheric noble gases are trapped in minerals crystallized during UHP metamorphism is unknown. We measured Ar and Ne trapped in phengite and omphacite from the youngest known UHP terrane on Earth to determine the composition of Ar and Ne returned from mantle depths to the surface by forearc recycling. An (40)Ar/(39)Ar age [7.93 ± 0.10 My (1σ)] for phengite is interpreted as the timing of crystallization at mantle depths and indicates that (40)Ar/(39)Ar phengite ages reliably record the timing of UHP metamorphism. Both phengite and omphacite yielded atmospheric (38)Ar/(36)Ar and (20)Ne/(22)Ne. Our study provides the first documentation, to our knowledge, of entrapment of atmospheric Ar and Ne in phengite and omphacite. Results indicate that a subduction barrier for atmospheric-derived noble gases does not exist at mantle depths associated with UHP metamorphism. We show that the crystallization age together with the isotopic composition of nonradiogenic noble gases trapped in minerals formed during subsolidus crystallization at mantle depths can be used to unambiguously assess forearc recycling of atmospheric noble gases. The flux of atmospheric noble gas entering the deep Earth through subduction and returning to the surface cannot be fully realized until the abundances of atmospheric noble gases trapped in exhumed UHP rocks are known.

  5. arXiv.org and Physics Education

    ERIC Educational Resources Information Center

    Ramlo, Susan

    2007-01-01

    The website arXiv.org (pronounced "archive") is a free online resource for full-text articles in the fields of physics, mathematics, computer science, nonlinear science, and quantitative biology that has existed for about 15 years. Available directly at http://www.arXiv.org, this e-print archive is searchable. As of Jan. 3, 2007, arXiv had open…

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

    SciTech Connect

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

    2015-10-15

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

  7. Mineralogy and Ar-39 - Ar-40 of an old pristine basalt: Thermal history of the HED parent body

    NASA Technical Reports Server (NTRS)

    Takeda, Hiroshi; Mori, Hiroshi; Bogard, Donald D.

    1994-01-01

    Previous investigations of mineral chemistry and Rb-Sr and Sm-Nd ages indicated that clast,84 from eucrite Yamato 75011 had preserved the pristine nature of its initial crystallization during an early stage of the HED parent body. Microscale mineralogy and Ar-39-Ar-40 ages of this clast, however, revealed local disturbance of microtextures and partially reset ages. This evidence suggests that, in addition to initial crystallization and rapid cooling, the Y75011,84 clast experienced shock deformation, reheating of short duration at higher temperature, and brecciation. These characteristics suggest two or more impact events. Fe-rich olivine filling fractures in pyroxene may have been introduced during the accompanying shock fracturing. The inferred Ar-39-Ar-40 degassing ages for Y75011 matrix and clast, 84 are 3.94 +/- 0.04 Ga and 3.98 +/- 0.03 Ga, respectively. The suggested degassing age for a clast from Y790020, believed to be paired with Y75011, is approximately 4.03 Ga, but could be younger. We consider it likely that all three samples experienced a common degassing event 3.95 +/- 0.05 Ga ago, but we cannot rule out two or more events spaced over a approximately 0.1 Ga interval. Higher temperature extractions of the two clast samples show significantly older apparent ages up to approximately 4.5 Ga and suggest that the time/temperature regime of this event was not sufficient to degas Ar totally. Most likely, the K-Ar ages were reset by thermal metamorphism associated with one or more impact events associated with shock fracturing, formation of Fe-rich olivine veins, and/or meteorite brecciation. The pyroxene annealing that commonly occurs in many eucrites is likely to be a much earlier process than the impact-produced textural changes and reset K-Ar ages observed in these meteorites. The existence of mineralogical and chronological evidence for metamorphism in an otherwise pristine eucrite suggests that the HED parent body experienced an extensive degree of

  8. Role of Penning ionization in the enhancement of streamer channel conductivity and Ar(1s{sub 5}) production in a He-Ar plasma jet

    SciTech Connect

    Sands, Brian L.; Huang, Shih K.; Speltz, Jared W.; Niekamp, Matthew A.; Ganguly, Biswa N.

    2013-04-21

    Plasma jet devices that use a helium gas flow mixed with a small percentage of argon have been shown to operate with a larger discharge current and enhanced production of the Ar(1s{sub 5}) metastable state, particularly in the discharge afterglow. In this experiment, time-resolved quantitative measurements of He(2{sup 3}S{sub 1}) and Ar(1s{sub 5}) metastable species were combined with current and spectrally resolved emission measurements to elucidate the role of Penning ionization in a helium plasma jet with a variable argon admixture. The plasma jet was enclosed in a glass chamber through which a flowing nitrogen background was maintained at 600 Torr. At 3%-5% Ar admixture, we observed a {approx}50% increase in the peak circuit current and streamer velocity relative to a pure helium plasma jet for the same applied voltage. The streamer initiation delay also decreased by {approx}20%. Penning ionization of ground-state argon was found to be the dominant quenching pathway for He(2{sup 3}S{sub 1}) up to 2% Ar and was directly correlated with a sharp increase in both the circuit current and afterglow production of Ar(1s{sub 5}) for Ar admixtures up to 1%, but not necessarily with the streamer velocity, which increased more gradually with Ar concentration. Ar(1s{sub 5}) was produced in the afterglow through recombination of Ar{sup +} and dissociative recombination of Ar{sub 2}{sup +} as the local mean electron energy decreased in the plasma channel behind the streamer head. The discharge current and argon metastable enhancement are contingent on the rapid production of He(2{sup 3}S{sub 1}) near the streamer head, >5 Multiplication-Sign 10{sup 12} cm{sup -3} in 30 ns under the conditions of this experiment.

  9. Variation of illite/muscovite 40Ar/39Ar age spectra during progressive low-grade metamorphism: an example from the US Cordillera

    NASA Astrophysics Data System (ADS)

    Verdel, Charles; van der Pluijm, Ben A.; Niemi, Nathan

    2012-09-01

    40Ar/39Ar step-heating data were collected from micron to submicron grain-sizes of correlative illite- and muscovite-rich Cambrian pelitic rocks from the western United States that range in metamorphic grade from the shallow diagenetic zone (zeolite facies) to the epizone (greenschist facies). With increasing metamorphic grade, maximum ages from 40Ar/39Ar release spectra decrease, as do total gas ages and retention ages. Previous studies have explained similar results as arising dominantly or entirely from the dissolution of detrital muscovite and precipitation/recrystallization of neo-formed illite. While recognizing the importance of these processes in evaluating our results, we suggest that the inverse correlation between apparent age and metamorphic grade is controlled, primarily, by thermally activated volume diffusion, analogous to the decrease in apparent ages with depth observed for many thermochronometers in borehole experiments. Our results suggest that complete resetting of the illite/muscovite Ar thermochronometer occurs between the high anchizone and epizone, or at roughly 300 °C. This empirical result is in agreement with previous calculations based on muscovite diffusion parameters, which indicate that muscovite grains with radii of 0.05-2 μm should have closure temperatures between 250 and 350 °C. At high anchizone conditions, we observe a reversal in the age/grain-size relationship (the finest grain-size produces the oldest apparent age), which may mark the stage in prograde subgreenschist facies metamorphism of pelitic rocks at which neo-formed illite/muscovite crystallites typically surpass the size of detrital muscovite grains. It is also approximately the stage at which neo-formed illite/muscovite crystallites develop sufficient Ar retentivity to produce geologically meaningful 40Ar/39Ar ages. Results from our sampling transect of Cambrian strata establish a framework for interpreting illite/muscovite 40Ar/39Ar age spectra at different

  10. Diffusion artifacts in dating by stepwise thermal release of rare gases. [Ar isotope lunar chronology

    NASA Technical Reports Server (NTRS)

    Huneke, J. C.

    1976-01-01

    It is demonstrated that the age of an isochron of apparent age plateau can be easily altered during a thermal release experiment, and that constant rare gas compositions can be observed which are artifacts of the experimental technique and are not chronologically meaningful. Examples are selected from 40Ar-39Ar dating of lunar samples in which anomalous variations in apparent ages can be ascribed to such experimental artifacts.

  11. Mineralogy, 40Ar/ 39Ar dating and apatite fission track dating of rocks along the Castle Mountain fault, Alaska

    NASA Astrophysics Data System (ADS)

    Parry, W. T.; Bunds, M. P.; Bruhn, R. L.; Hall, C. M.; Murphy, J. M.

    2001-07-01

    The Castle Mountain fault is a 200-km-long, right-lateral fault that forms the northern boundary of the Cook Inlet basin and Matanuska Valley, Alaska. Fault gouge and fault rock at six localities contain the clay minerals illite, smectite, chlorite, and interstratified illite/smectite. At one locality, gouge contains deformed illite/smectite with very little wall rock chlorite contamination. Fine (<0.03 μm), medium (0.03-0.2 μm), and coarse (0.2-2.0 μm) illite/smectite from this site were dated using 40Ar/ 39Ar micro-encapsulation and laser microprobe methods. Total gas ages for the three size fractions are 28.21±0.12, 32.42±0.11 and 36.24±0.08 Ma for fine to coarse sizes respectively. Argon retention ages obtained from 40Ar and 39Ar retained in the three size fractions of illite at room temperature during neutron irradiation are 37.36±0.15, 42.11±0.14 and 47.20±0.10 respectively. Apatite fission track ages were measured in arkose at a locality on the fault 60 km west of the gouge locality. Three samples of arkose were dated: one within 10 m of the fault core, one 170 m from the fault, and one 335 m from the fault. The sample nearest to the fault yielded an age of 29.3±2.8 Ma, but it only had four track lengths at 10-13 μm. Two apatite grains from the intermediate sample yielded a pooled age of 34.3±6.1 Ma. The distant sample (25 grains counted, 101 track lengths) yielded an age of 32.0±2.9 Ma. This sample has a broad distribution of track lengths and a broad distribution of individual grain ages ranging from 14.8±5.1 to 67.8±8.8 Ma. Monte Carlo modeling of the apatite age and track length data is consistent with hydrothermal mineralization at 37-39 Ma followed by rapid uplift and cooling after 10 Ma. The 40Ar/ 39Ar total gas ages (K-Ar) are minimum ages, and the argon retention ages are maximum ages. The thermal model derived from the fission track data, and the argon retention age for the finest illite fraction of ˜37 Ma date a hydrothermal

  12. Broadband dynamic phase matching of high-order harmonic generation by a high-peak-power soliton pump field in a gas-filled hollow photonic-crystal fiber.

    PubMed

    Serebryannikov, Evgenii E; von der Linde, Dietrich; Zheltikov, Aleksei M

    2008-05-01

    Hollow-core photonic-crystal fibers are shown to enable dynamically phase-matched high-order harmonic generation by a gigawatt soliton pump field. With a careful design of the waveguide structure and an appropriate choice of input-pulse and gas parameters, a remarkably broadband phase matching can be achieved for a soliton pump field and a large group of optical harmonics in the soft-x-ray-extreme-ultraviolet spectral range.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  14. Ar-40/Ar-39 age determinations for the Rotoiti eruption, New Zealand

    NASA Astrophysics Data System (ADS)

    Flude, S.; Storey, M.

    2013-12-01

    The contemporaneous Rotoiti and Earthquake Flat ignimbrites, erupted from the Taupo Volcanic zone, New Zealand, form a distinctive tephrostratigraphic horizon in the Southern Pacific. Radioisotopic dating results for these eruptions remain controversial, with published ages ranging from 35.1 × 2.8 ka [1] to 71 × 6 ka [2], with 61.0 × 1.5 ka [3] often being cited as the most widely accepted age. These eruptions are difficult to date as their age is near the limit for various radiometric dating techniques, which are complicated by a large proportion of inherited material (xenocrysts) and a lack of phases suitable for dating. Glass-bearing plutonic blocks erupted with the Rotoiti and Earthquake Flat ignimbrites have previously been interpreted as deriving from a slowly cooled and incompletely solidified magma body that was sampled by the eruptions. They contain large vugs lined with euhedral quartz, sanidine and biotite crystals, indicating that these crystals grew in a gas or aqueous fluid rich environment and are interpreted to have formed shortly before or during eruption. Here we will present Ar-40/Ar-39 ages for sanidines and biotites extracted from vugs in lithic blocks erupted as part of the Earthquake Flat ignimbrite. We show that, even for vug-lining material, inherited ages remain a problem and are the likely source of the wide variation in published radiometric ages. Nevertheless, many of the Ar-40/Ar-39 ages are much younger than the 61 ka age [3] and are more consistent with the recent stratigraphic, C-14 and U-238/Th-230+(U-Th)/He ages that have been suggested (e.g. [4,5]). 1. Whitehead, N. & Ditchburn, R. New Zealand Journal of Geology and Geophysics 37, 381-383 (1994). 2. Ota, Y., Omura, A. & Iwata, H. New Zealand Journal of Geology and Geophysics 32, 327-331 (1989). 3. Wilson, C. J. N. et al. Quaternary Science Reviews 26, 1861-1870 (2007). 4. Molloy, C., Shane, P. & Augustinus, P. Geological Society of America Bulletin 121, 1666-1677 (2009). 5

  15. Evaluation of sintering effects on SiC incorporated UO2 kernels under Ar and Ar-4%H2 environments

    SciTech Connect

    Silva, Chinthaka M; Lindemer, Terrence; Hunt, Rodney Dale; Collins, Jack Lee; Terrani, Kurt A; Snead, Lance Lewis

    2013-01-01

    Silicon carbide (SiC) is suggested as an oxygen getter in UO2 kernels used for TRISO particle fuels to lower oxygen potential and prevent kernel migration during irradiation. Scanning electron microscopy and X-ray diffractometry analyses performed on sintered kernels verified that internal gelation process can be used to incorporate SiC in urania fuel kernels. Sintering in either Ar or Ar-4%H2 at 1500 C lowered the SiC content in the UO2 kernels to some extent. Formation of UC was observed as the major chemical phase in the process, while other minor phases such as U3Si2C2, USi2, U3Si2, and UC2 were also identified. UC formation was presumed to be occurred by two reactions. The first was the SiC reaction with its protective SiO2 oxide layer on SiC grains to produce volatile SiO and free carbon that subsequently reacted with UO2 to form UC. The second process was direct UO2 reaction with SiC grains to form SiO, CO, and UC, especially in Ar-4%H2. A slightly higher density and UC content was observed in the sample sintered in Ar-4%H2, but the use of both atmospheres produced kernels with ~95% of theoretical density. It is suggested that incorporating CO in the sintering gas would prevent UC formation and preserve the initial SiC content.

  16. Optical emission diagnostics with electric probe measurements of inductively coupled Ar/O{sub 2}/Ar-O{sub 2} plasmas

    SciTech Connect

    Chung, T. H.; Kang, Hae Ra; Bae, Min Keun

    2012-11-15

    Physical properties of low-pressure inductively coupled argon, oxygen, and Ar-O{sub 2} mixture plasmas are investigated using optical emission spectroscopy (OES) combined with an rf-compensated Langmuir probe measurement. In each gas discharge, the electron density and the electron temperature were obtained by using the probe. The electron temperature was also obtained by OES models and compared with that measured by the probe. The electron temperature was observed to decrease with increasing power and pressure and also observed to decrease with increasing Ar content. Argon metastable densities were calculated based on an optical transition model. In Ar-O{sub 2} discharges, the dissociation fraction of O{sub 2} molecules was estimated using optical emission actinometry. The dissociation fraction was observed to increase with increasing power and Ar content.

  17. Production of Ar metastables in a dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Mikheyev, Pavel A.; Han, Jiande; Clark, Amanda; Sanderson, Carl; Heaven, Michael C.

    2017-01-01

    The results of experiments with a dielectric barrier discharge (DBD) are presented, where the production of metastable argon atoms was studied. The recently proposed optically pumped all-rare-gas laser (OPRGL) utilizes metastable atoms of heavier rare gases as lasing species. The required number density of metastables for efficient laser operation is 1012÷1013 cm-3 in an atmospheric pressure of He buffer gas. Recent experiments had shown that such densities are easily produced in a nanosecond pulsed discharge, even at pressures larger than atmospheric, but problems appear when one is trying to produce them in a CW regime. The reason for difficulties in the CW production of metastables at an atmospheric pressure seems to be the low value of the E/N parameter (<5-6 Td). In our experiments a 20 KHz DBD in 2-5% Ar mixture with He at an atmospheric pressure was studied. [Ar(1s5)] number density of the order of 1012 cm-3 was readily achieved. Temporal behavior of [Ar(1s5)] throughout the DBD cycle was obtained. The results demonstrate the feasibility of DBDs for OPRGL development.

  18. Preparation of water and ice samples for 39Ar dating by atom trap trace analysis (ATTA)

    NASA Astrophysics Data System (ADS)

    Schwefel, R.; Reichel, T.; Aeschbach-Hertig, W.; Wagenbach, D.

    2012-04-01

    Atom trap trace analysis (ATTA) is a new and promising method to measure very rare noble gas radioisotopes in the environment. The applicability of this method for the dating of very old groundwater with 81Kr has already been demonstrated [1]. Recent developments now show its feasibility also for the analysis of 39Ar [2,3], which is an ideal dating tracer for the age range between 50 and 1000 years. This range is of interest in the fields of hydro(geo)logy, oceanography, and glaciology. We present preparation (gas extraction and Ar separation) methods for groundwater and ice samples for later analysis by the ATTA technique. For groundwater, the sample size is less of a limitation than for applications in oceanography or glaciology. Large samples are furthermore needed to enable a comparison with the classical method of 39Ar detection by low-level counting. Therefore, a system was built that enables gas extraction from several thousand liters of water using membrane contactors. This system provides degassing efficiencies greater than 80 % and has successfully been tested in the field. Gas samples are further processed to separate a pure Ar fraction by a gas-chromatographic method based on Li-LSX zeolite as selective adsorber material at very low temperatures. The gas separation achieved by this system is controlled by a quadrupole mass spectrometer. It has successfully been tested and used on real samples. The separation efficiency was found to be strongly temperature dependent in the range of -118 to -130 °C. Since ATTA should enable the analysis of 39Ar on samples of less than 1 ccSTP of Ar (corresponding to about 100 ml of air, 2.5 l of water or 1 kg of ice), a method to separate Ar from small amounts of gas was developed. Titanium sponge was found to absorb 60 ccSTP of reactive gases per g of the getter material with reasonably high absorption rates at high operating temperatures (~ 800 ° C). Good separation (higher than 92 % Ar content in residual gas) was

  19. Method and apparatus for filling thermal insulating systems

    DOEpatents

    Arasteh, D.K.

    1992-01-14

    A method for filling insulated glazing units is disclosed. The method utilizes a vacuum chamber in which the insulated glazing units are placed. The insulated glazing units and vacuum chamber are evacuated simultaneously. The units are then refilled with a low conductance gas such as Krypton while the chamber is simultaneously refilled with air. 3 figs.

  20. Method and apparatus for filling thermal insulating systems

    DOEpatents

    Arasteh, Dariush K.

    1992-01-01

    A method for filling insulated glazing units is disclosed. The method utilizes a vacuum chamber in which the insulated glazing units are placed. The insulated glazing units and vacuum chamber are evacuated simultaneously. The units are then refilled with a low conductance gas such as Krypton while the chamber is simultaneously refilled with air.

  1. Interpretation of discordant 40Ar/39Ar age-spectra of mesozoic tholeiites from antarctica

    USGS Publications Warehouse

    Fleck, R.J.; Sutter, J.F.; Elliot, D.H.

    1977-01-01

    Conventional K-Ar ages of tholeiitic basalts of the Ferrar Group in the central Transantarctic Mountains indicate significant loss of radiogenic 40Ar from this unit over much of its outcrop area. Argon loss varies inversely with amount of devitrified matrix in the basalts, which have not been thermally or tectonically disturbed since extrusion. 40Ar/19Ar age-spectra of these tholeiites are generally discordant and indicate significant inhomogeneity in the distribution of radiogenic 40Ar with respect to 39Ar, but are distinctly different from release patterns of thermally disturbed samples. Amounts of argon redistribution vary directly with amounts of devitrification and are reflected in progressive modification of the age spectra. A model of redistribution of radiogenic 40Ar by devitrification of originally glassy matrix is suggested that is consistent with disturbance of the conventional K-Ar systematics as well as the 40Ar/39Ar age-spectra. Samples with substantial redistribution but minor loss of radiogenic argon yield age spectra whose apparent ages decrease from low-temperature to high-temperature steps, similar to those reported for some lunar basalts, breccias, and soils. Modification of all the age spectra is attributed to redistribution of radiogenic 40Ar during progressive devitrification, although 39Ar-recoil effects suggested by Turner and Cadogan (1974) may be a factor in some cases. Where devitrification involves most potassium sites within the basalt, 40Ar/39Ar age-plateaux may be formed that have no geologic significance. ?? 1977.

  2. Toward a high-resolution 40Ar/39Ar geochronology of the Tatun Volcano Group, Taiwan

    NASA Astrophysics Data System (ADS)

    Mesko, G. T.; Song, S.; Chang, S.; Hemming, S. R.; Turrin, B. D.

    2010-12-01

    Creek sanidine monitor standard, with an assumed age of 1.193±.001Ma (Nomade et al., 2005, Chemical Geology). Multiple-grain step-heating analyses using 3 to 5 steps were executed on several aliquots of the samples using a VG5400 noble gas mass spectrometer equipped with a 30W CO2 laser. Ages were calculated using the isochron method on all the steps run for each sample in order to avoid the necessity of assuming an initial composition and so all of the data points from a single irradiation could be plotted together. The results have yielded ages far younger than previously reported in all of the TVG, with very unradiogenic Ar and with 40Ar/36Ar intercepts that are mostly higher than the atmospheric ratio of 298.56±0.31 (Lee et al., 2006, Geochimica et Cosmochimica Acta). The second eruptive stage (using eruptive stages mapped by Lai et al., 2010, TAO) yielded ages in different locations of .053±.012Ma and .052±.014Ma. A third sample that was previously mapped in this stage yielded an age of .17±.03Ma. We have not yet been successful at obtaining reliable results on the stratigraphically youngest sample.

  3. Thermal plasma properties for Ar-Al, Ar-Fe and Ar-Cu mixtures used in welding plasmas processes: I. Net emission coefficients at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Cressault, Y.; Gleizes, A.

    2013-10-01

    This article is devoted to the calculation of the net emission coefficient (NEC) of Ar-Al, Ar-Fe and Ar-Cu mixtures at atmospheric pressure for arc welding processes. The results are given in data tables for temperatures between 3 kK and 30 kK, for five plasma thicknesses (0, 0.5, 1, 2, 5 mm) and ten concentrations of metallic vapours (pure gas, 0.01%, 0.1%, 1%, 5%, 10%, 25%, 50%, 75% and pure metal vapours in mass proportions). The results are in good agreement with most of the works published on the subject for such mixtures. They highlight the influence of three parameters on the radiation of the plasma: the NEC is directly related to temperature and inversely related to plasma radius and is highly sensitive to the presence of metal vapours. Finally, numerical data are supplied in tables in order to develop accurate computational modelling of welding arc and to estimate both qualitatively and quantitatively the influence of each metallic vapour on the size and on the shape of the weld pool.

  4. Pneumatically sprayed Cu2ZnSnS4 films under Ar and Ar-H2 atmosphere

    NASA Astrophysics Data System (ADS)

    Espindola Rodriguez, M.; Sylla, D.; Sanchez, Y.; López-Marino, S.; Fontané, X.; López-García, J.; Placidi, M.; Pérez-Rodríguez, A.; Vigil-Galán, O.; Saucedo, E.

    2014-06-01

    Cu2ZnSnS4 (CZTS) thin films have been deposited by pneumatic spray pyrolysis onto soda-lime glass and Mo-coated glass substrates by using a special reactor designed for working under controlled atmospheres. The films were grown using both Ar and Ar-H2 as the carrier gas and atmosphere, aiming to eliminate the oxygen-containing atmosphere from the classical spray pyrolysis configuration that uses air as the carrier gas. Thin films with different compositions were prepared and thermally annealed to investigate its compositional and physical properties and its performance as absorber layers in solar cells. To know the impact of the thermal annealing, two different annealing temperatures were used: 550 and 580 °C, both for 30 min. The last temperature showed a great improvement in the crystallinity and allowed a better incorporation of Sn into the films. The optical band gap of the annealed films was found to be around 1.45 eV. Cu-S and ZnO were found as contaminant phases in the as-grown Ar-sprayed samples, but were effectively transformed after annealing. ZnS was detected in both the as-grown and annealed films as the main secondary phase. Solar cells free of scarce elements were fabricated showing an improved conversion efficiency of 1.4%, evidencing the higher potential of this approach for the synthesis of device-grade films.

  5. Mars Atmospheric History Derived from Upper-Atmospheric Structure of 38Ar/36Ar Measured From MAVEN

    NASA Astrophysics Data System (ADS)

    Jakosky, Bruce; Slipski, Marek; Benna, Mehdi; Mahaffy, Paul; Elrod, Meredith K.; Yelle, Roger; Stone, Shane; Alsaeed, Noora

    2016-10-01

    Measurements of the structure of the Martian upper atmosphere made from MAVEN observations allow us to derive homopause and exobase altitudes in the Mars upper atmosphere and to determine the isotopic fractionation that occurs between them. Fractionation in the ratio of 38Ar/36Ar occurs between the homopause and exobase due to diffusive separation. This fractionation, combined with measurements of the bulk atmospheric ratio, is used to determine the total amount of argon lost to space by pick-up-ion sputtering. Our analysis is based on Rayleigh distillation, modified by replenishment of gas to the atmosphere by outgassing, impact, and crustal weathering. Approximately 80 % of the 36Ar that was ever in the atmosphere has been removed through time. This high value requires that a major fraction of Mars atmospheric gas has been lost to space. It points strongly to loss to space as having been the dominant mechanism driving the transition in Martian climate from an early, warm, wet environment to today's cold, dry, thin atmosphere.

  6. Xe and Ar nanobubbles in Al studied by photoemission spectroscopy

    SciTech Connect

    Dhaka, R. S.; Biswas, C.; Shukla, A. K.; Barman, S. R.; Chakrabarti, Aparna

    2008-03-01

    We have studied xenon and argon bubbles formed in the subsurface region of Al(111) by x-ray photoelectron spectroscopy. As a consequence of the nanometer size of the bubbles, the photohole formed by Xe 3d or Ar 2p photoemission is screened by the Al conduction electrons, which substantially lowers the binding energy (BE) as compared to the gas phase. As the bubble size increases, the Al conduction electron screening decreases and the BE increases. On the basis of density functional theory, we show that the change in the bubble pressure with size is not responsible for the BE shift of inner shell core levels, such as Xe 3d or Ar 2p. On the other hand, an increase in BE with bubble size for outer shell core levels, such as Ar 3p, could be due to a decrease in both pressure and Al conduction electron screening. The core level line shape also changes with bubble size. For example, the spectra are broadened due to the distribution of the bubble radius around its mean value, and an asymmetry for small bubbles is observed that decreases for larger bubbles. An annealing of Xe and Ar bubbles after an implantation up to 640 K shows that the BE increases with annealing temperature. Since it is well known that bubble size increases with annealing temperature, this further supports our contention of BE shift with bubble size. A defect induced partial disorder of the Al(111) surface by Xe and Ar bombardment is observed by low energy electron diffraction, but this does not affect the Al 2p BE and line shape.

  7. ACTH Action on StAR Biology.

    PubMed

    Clark, Barbara J

    2016-01-01

    Adrenocorticotropin hormone (ACTH) produced by the anterior pituitary stimulates glucocorticoid synthesis by the adrenal cortex. The first step in glucocorticoid synthesis is the delivery of cholesterol to the mitochondrial matrix where the first enzymatic reaction in the steroid hormone biosynthetic pathway occurs. A key response of adrenal cells to ACTH is activation of the cAMP-protein kinase A (PKA) signaling pathway. PKA activation results in an acute increase in expression and function of the Steroidogenic Acute Regulatory protein (StAR). StAR plays an essential role in steroidogenesis- it controls the hormone-dependent movement of cholesterol across the mitochondrial membranes. Currently StAR's mechanism of action remains a major unanswered question in the field. However, some insight may be gained from understanding the mechanism(s) controlling the PKA-dependent phosphorylation of StAR at S194/195 (mouse/human StAR), a modification that is required for function. This mini-review provides a background on StAR's biology with a focus on StAR phosphorylation. The model for StAR translation and phosphorylation at the outer mitochondrial membrane, the location for StAR function, is presented to highlight a unifying theme emerging from diverse studies.

  8. ACTH Action on StAR Biology

    PubMed Central

    Clark, Barbara J.

    2016-01-01

    Adrenocorticotropin hormone (ACTH) produced by the anterior pituitary stimulates glucocorticoid synthesis by the adrenal cortex. The first step in glucocorticoid synthesis is the delivery of cholesterol to the mitochondrial matrix where the first enzymatic reaction in the steroid hormone biosynthetic pathway occurs. A key response of adrenal cells to ACTH is activation of the cAMP-protein kinase A (PKA) signaling pathway. PKA activation results in an acute increase in expression and function of the Steroidogenic Acute Regulatory protein (StAR). StAR plays an essential role in steroidogenesis- it controls the hormone-dependent movement of cholesterol across the mitochondrial membranes. Currently StAR's mechanism of action remains a major unanswered question in the field. However, some insight may be gained from understanding the mechanism(s) controlling the PKA-dependent phosphorylation of StAR at S194/195 (mouse/human StAR), a modification that is required for function. This mini-review provides a background on StAR's biology with a focus on StAR phosphorylation. The model for StAR translation and phosphorylation at the outer mitochondrial membrane, the location for StAR function, is presented to highlight a unifying theme emerging from diverse studies. PMID:27999527

  9. Androgen receptor (AR) in cardiovascular diseases.

    PubMed

    Huang, Chiung-Kuei; Lee, Soo Ok; Chang, Eugene; Pang, Haiyan; Chang, Chawnshang

    2016-04-01

    Cardiovascular diseases (CVDs) are still the highest leading cause of death worldwide. Several risk factors have been linked to CVDs, including smoking, diabetes, hyperlipidemia, and gender among others. Sex hormones, especially the androgen and its receptor, androgen receptor (AR), have been linked to many diseases with a clear gender difference. Here, we summarize the effects of androgen/AR on CVDs, including hypertension, stroke, atherosclerosis, abdominal aortic aneurysm (AAA), myocardial hypertrophy, and heart failure, as well as the metabolic syndrome/diabetes and their impacts on CVDs. Androgen/AR signaling exacerbates hypertension, and anti-androgens may suppress hypertension. Androgen/AR signaling plays dual roles in strokes, depending on different kinds of factors; however, generally males have a higher incidence of strokes than females. Androgen and AR differentially modulate atherosclerosis. Androgen deficiency causes elevated lipid accumulation to enhance atherosclerosis; however, targeting AR in selective cells without altering serum androgen levels would suppress atherosclerosis progression. Androgen/AR signaling is crucial in AAA development and progression, and targeting androgen/AR profoundly restricts AAA progression. Men have increased cardiac hypertrophy compared with age-matched women that may be due to androgens. Finally, androgen/AR plays important roles in contributing to obesity and insulin/leptin resistance to increase the metabolic syndrome.

  10. Development of a Low-Level Ar-37 Calibration Standard

    SciTech Connect

    Williams, Richard M.; Aalseth, Craig E.; Bowyer, Ted W.; Day, Anthony R.; Fuller, Erin S.; Haas, Derek A.; Hayes, James C.; Hoppe, Eric W.; Humble, Paul H.; Keillor, Martin E.; LaFerriere, Brian D.; Mace, Emily K.; McIntyre, Justin I.; Miley, Harry S.; Myers, Allan W.; Orrell, John L.; Overman, Cory T.; Panisko, Mark E.; Seifert, Allen

    2016-03-07

    Argon-37 is an important environmental signature of an underground nuclear explosion. Producing and quantifying low-level 37Ar standards is an important step in the development of sensitive field measurement instruments for use during an On-Site Inspection, a key provision of the Comprehensive Nuclear-Test-Ban Treaty. This paper describes progress at Pacific Northwest National Laboratory (PNNL) in the development of a process to generate and quantify low-level 37Ar standard material, which can then be used to calibrate sensitive field systems at activities consistent with soil background levels. The 37Ar used for our work was generated using a laboratory-scale, high-energy neutron source to irradiate powdered samples of calcium carbonate. Small aliquots of 37Ar were then extracted from the head space of the irradiated samples. The specific activity of the head space samples, mixed with P10 (90% stable argon:10% methane by mole fraction) count gas, is then derived using the accepted Length-Compensated Internal-Source Proportional Counting method. Due to the low activity of the samples, a set of three Ultra-Low Background Proportional-Counters designed and fabricated at PNNL from radio-pure electroformed copper was used to make the measurements in PNNL’s shallow underground counting laboratory. Very low background levels (<10 counts/day) have been observed in the spectral region near the 37Ar emission feature at 2.8 keV. Two separate samples from the same irradiation were measured. The first sample was counted for 12 days beginning 28 days after irradiation, the second sample was counted for 24 days beginning 70 days after irradiation (the half-life of 37Ar is 35.0 days). Both sets of measurements were analyzed and yielded very similar results for the starting activity (~0.1 Bq) and activity concentration (0.15 mBq/ccSTP argon) after P10 count gas was added. A detailed uncertainty model was developed based on the ISO Guide to the Expression of Uncertainty in

  11. (40)Ar/(39)Ar dating, paleomagnetism, and tephrochemistry of Pliocene strata of the hominid-bearing Woranso-Mille area, west-central Afar Rift, Ethiopia.

    PubMed

    Deino, Alan L; Scott, Gary R; Saylor, Beverly; Alene, Mulugeta; Angelini, Joshua D; Haile-Selassie, Yohannes

    2010-02-01

    (40)Ar/(39)Ar dating of tuffs and mafic lavas, tephra geochemistry, and paleomagnetic reversal stratigraphy have been used to establish the chronostratigraphy of the Pliocene hominid-bearing fossiliferous succession at Woranso-Mille, a paleontological study area in the western part of the central Afar region of Ethiopia. The succession in the northwestern part of the study area ranges in (40)Ar/(39)Ar age from 3.82-3.570 Ma, encompassed by paleomagnetic subchron C2Ar (4.187-3.596 Ma). One of the major tuff units, locally named the Kilaytoli tuff, is correlative on the basis of age and geochemistry to the Lokochot Tuff of the Turkana Basin. A hominid partial skeleton (KSD-VP-1) was found in strata whose precise stratigraphic position and age is still under investigation, but is believed to correspond to the later part of this interval. Woranso-Mille fills a significant gap in the fossil record of northeastern Africa at the time of the lower to middle Pliocene transition, when many extant species lineages of African fauna were established.

  12. Gas vesicles.

    PubMed Central

    Walsby, A E

    1994-01-01

    The gas vesicle is a hollow structure made of protein. It usually has the form of a cylindrical tube closed by conical end caps. Gas vesicles occur in five phyla of the Bacteria and two groups of the Archaea, but they are mostly restricted to planktonic microorganisms, in which they provide buoyancy. By regulating their relative gas vesicle content aquatic microbes are able to perform vertical migrations. In slowly growing organisms such movements are made more efficiently than by swimming with flagella. The gas vesicle is impermeable to liquid water, but it is highly permeable to gases and is normally filled with air. It is a rigid structure of low compressibility, but it collapses flat under a certain critical pressure and buoyancy is then lost. Gas vesicles in different organisms vary in width, from 45 to > 200 nm; in accordance with engineering principles the narrower ones are stronger (have higher critical pressures) than wide ones, but they contain less gas space per wall volume and are therefore less efficient at providing buoyancy. A survey of gas-vacuolate cyanobacteria reveals that there has been natural selection for gas vesicles of the maximum width permitted by the pressure encountered in the natural environment, which is mainly determined by cell turgor pressure and water depth. Gas vesicle width is genetically determined, perhaps through the amino acid sequence of one of the constituent proteins. Up to 14 genes have been implicated in gas vesicle production, but so far the products of only two have been shown to be present in the gas vesicle: GvpA makes the ribs that form the structure, and GvpC binds to the outside of the ribs and stiffens the structure against collapse. The evolution of the gas vesicle is discussed in relation to the homologies of these proteins. Images PMID:8177173

  13. XRD-based 40Ar/39Ar age correction for fine-grained illite, with application to folded carbonates in the Monterrey Salient (northern Mexico)

    NASA Astrophysics Data System (ADS)

    Fitz-Díaz, Elisa; Hall, Chris M.; van der Pluijm, Ben A.

    2016-05-01

    Due to their minute size, 40Ar/39Ar analysis of illite faces significant analytical challenges, including mineral characterization and, especially, effects of grain size and crystallography on 39Ar recoil. Quantifying the effects of 39Ar recoil requires the use of sample vacuum encapsulation during irradiation, which permits the measurement of the fraction of recoiled 39Ar as well as the 39Ar and 40Ar∗ retained within illite crystals that are released during step heating. Total-Gas Ages (TGA) are calculated by using both recoiled and retained argon, which is functionally equivalent to K-Ar ages, while Retention Ages (RA) only involve retained Ar in the crystal. Natural applications have shown that TGA fits stratigraphic constraints of geological processes when the average illite crystallite thickness (ICT) is smaller than 10 nm, and that RA matches these constraints for ICTs larger than 50 nm. We propose a new age correction method that takes into account the average ICT and corresponding recoiled 39Ar for a sample, with X-ray Corrected Ages (XCA) lying between Total-Gas and Retention Ages depending on ICT. This correction is particularly useful in samples containing authigenic illite formed in the anchizone, with typical ICT values between 10 and 50 nm. In three samples containing authigenic illite from Cretaceous carbonates in the Monterrey Salient in northern Mexico, there is a range in TGAs among the different size-fractions of 46-49, 36-43 and 40-52 Ma, while RAs range from 54-64, 47-52 and 53-54 Ma, respectively. XCA calculations produce tighter age ranges for these samples of 52.5-56, 45.5-48.5 and 49-52.5 Ma, respectively. In an apparent age vs ICT or %2M 1illite plot, authigenic illite grains show a slope that is in general slightly positive for TGA, slightly negative for RA, but close to zero for XCA, with thinner crystallites showing more dispersion than thicker ones. In order to test if dispersion is due to a different formation history or the result

  14. Filling carbon nanotubes with particles.

    PubMed

    Kim, Byong M; Qian, Shizhi; Bau, Haim H

    2005-05-01

    The filling of carbon nanotubes (CNTs) with fluorescent particles was studied experimentally and theoretically. The fluorescent signals emitted by the particles were visible through the walls of the nanotubes, and the particles inside the tubes were observable with an electron microscope. Taking advantage of the template-grown carbon nanotubes' transparency to fluorescent light, we measured the filling rate of the tubes with particles at room conditions. Liquids such as ethylene glycol, water, and ethylene glycol/water mixtures, laden with 50 nm diameter fluorescent particles, were brought into contact with 500 nm diameter CNTs. The liquid and the particles' transport were observed, respectively, with optical and fluorescence microscopy. The CNTs were filled controllably with particles by the complementary action of capillary forces and the evaporation of the liquid. The experimental results were compared and favorably agreed with theoretical predictions. This is the first report on fluorescence studies of particle transport in carbon nanotubes.

  15. Fluid circulation and reservoir conditions of the Los Humeros Geothermal Field (LHGF), Mexico, as revealed by a noble gas survey

    NASA Astrophysics Data System (ADS)

    Pinti, Daniele L.; Castro, M. Clara; Lopez-Hernandez, Aida; Han, Guolei; Shouakar-Stash, Orfan; Hall, Chris M.; Ramírez-Montes, Miguel

    2017-03-01

    Los Humeros Geothermal Field (LHGF) is one of four geothermal fields currently operating in Mexico, in exploitation since 1990. Located in a caldera complex filled with very low-permeability rhyolitic ignimbrites that are the reservoir cap-rock, recharge of the geothermal field is both limited and localized. Because of this, planning of any future geothermal exploitation must be based on a clear understanding of the fluid circulation. To this end, a first noble gas survey was carried out in which twenty-two production wells were sampled for He, Ne, Ar, Kr, and Xe isotope analysis. Air-corrected 3He/4He ratios (Rc) measured in the fluid, normalized to the helium atmospheric ratio (Ra; 1.384 × 10- 6), are consistently high across the field, with an average value of 7.03 ± 0.40 Ra. This value is close to that of the sub-continental upper mantle, indicating that LHGF mines heat from an active magmatic system. Freshwater recharge does not significantly affect He isotopic ratios, contributing 1-10% of the total fluid amount. The presence of radiogenic 40Ar* in the fluid suggests a fossil fluid component that might have circulated within the metacarbonate basement with radiogenic argon produced from detrital dispersed illite. Solubility-driven elemental fractionation of Ne/Ar, Kr/Ar, and Xe/Ar confirm extreme boiling in the reservoir. However, a combined analysis of these ratios with 40Ar/36Ar reveals mixing with an air component, possibly introduced by re-injected geothermal fluids.

  16. Paleovalley fills: Trunk vs. tributary

    USGS Publications Warehouse

    Kvale, E.P.; Archer, A.W.

    2007-01-01

    A late Mississippian-early Pennsylvanian eustatic sea level drop resulted in a complex lowstand drainage network being eroded across the Illinois Basin in the eastern United States. This drainage system was filled during the early part of the Pennsylvanian. Distinct differences can be recognized between the trunk and tributary paleovalley fills. Fills preserved within the trunk systems tend to be fluvially dominated and consist of bed-load deposits of coarse- to medium-grained sandstone and conglomerate. Conversely, the incised valleys of tributary systems tend to be filled with dark mudstone, thinly interbedded sandstones, and mudstones and siltstones. These finer grained facies exhibit marine influences manifested by tidal rhythmites, certain traces fossils, and macro- and microfauna. Examples of tributary and trunk systems, separated by no more than 7 km (4.3 mi) along strike, exhibit these styles of highly contrasting fills. Useful analogs for understanding this Pennsylvanian system include the Quaternary glacial sluiceways present in the lower Ohio, White, and Wabash river valleys of Indiana (United States) and the modern Amazon River (Brazil). Both the Amazon River and the Quaternary rivers of Indiana have (or had) trunk rivers that are (were) dominated by large quantities of bed load relative to their tributaries. The trunk valley systems of these analogs aggraded much more rapidly than their tributary valleys, which evolved into lakes because depositional rates along the trunk are (were) so high that the mouths of the tributaries have been dammed by bed-load deposits. These Holocene systems illustrate that sediment yields can significantly influence the nature of fill successions within incised valleys independent of rates of sea level changes or proximity to highstand coastlines. Copyright ?? 2007. The American Association of Petroleum Geologists. All rights reserved.

  17. XeCl Avalanche discharge laser employing Ar as a diluent

    DOEpatents

    Sze, Robert C.

    1981-01-01

    A XeCl avalanche discharge exciplex laser which uses a gaseous lasing starting mixture of: (0.2%-0.4% chlorine donor/2.5%-10% Xe/97.3%-89.6% Ar). The chlorine donor normally comprises HCl but can also comprise CCl.sub.4 BCl.sub.3. Use of Ar as a diluent gas reduces operating pressures over other rare gas halide lasers to near atmospheric pressure, increases output lasing power of the XeCl avalanche discharge laser by 30% to exceed KrF avalanche discharge lasing outputs, and is less expensive to operate.

  18. XeCl avalanche discharge laser employing Ar as a diluent

    DOEpatents

    Sze, R.C.

    1979-10-10

    A XeCl avalanche discharge exciplex laser which uses a gaseous lasing starting mixture of: 0.2 to 0.4% chlorine donor/2.5% to 10% Xe/97.3% to 89.6% Ar) is provided. The chlorine donor normally comprises HCl but can also comprise CCl/sub 4/ BCl/sub 3/. Use of Ar as a diluent gas reduces operating pressures over other rare gas halide lasers to near atmospheric pressure, increases output lasing power of the XeCl avalanche discharge laser by 30% to exceed KrF avalanche discharge lasing outputs, and is less expensive to operate.

  19. Ion kinetics in Ar/H2 cold plasmas: the relevance of ArH+

    PubMed Central

    Jiménez-Redondo, Miguel; Cueto, Maite; Doménech, José Luis; Tanarro, Isabel; Herrero, Víctor J.

    2015-01-01

    The recent discovery of ArH+ in the interstellar medium has awakened the interest in the chemistry of this ion. In this work, the ion-molecule kinetics of cold plasmas of Ar/H2 is investigated in glow discharges spanning the whole range of [H2]/([H2]+[Ar]) proportions for two pressures, 1.5 and 8 Pa. Ion concentrations are determined by mass spectrometry, and electron temperatures and densities, with Langmuir probes. A kinetic model is used for the interpretation of the results. The selection of experimental conditions evinces relevant changes with plasma pressure in the ion distributions dependence with the H2 fraction, particularly for the major ions: Ar+, ArH+ and H3+. At 1.5 Pa, ArH+ prevails for a wide interval of H2 fractions: 0.3<[H2]/([H2]+[Ar])<0.7. Nevertheless, a pronounced displacement of the ArH+ maximum towards the lowest H2 fractions is observed at 8 Pa, in detriment of Ar+, which becomes restricted to very small [H2]/([H2]+[Ar]) ratios, whereas H3+ becomes dominant for all [H2]/([H2]+[Ar]) > 0.1. The analysis of the data with the kinetic model allows the identification of the sources and sinks of the major ions over the whole range of experimental conditions sampled. Two key factors turn out to be responsible for the different ion distributions observed: the electron temperature, which determines the rate of Ar+ formation and thus of ArH+, and the equilibrium ArH+ + H2 ⇄ H3+ + Ar, which can be strongly dependent of the degree of vibrational excitation of H3+. The results are discussed and compared with previously published data on other Ar/H2 plasmas. PMID:26702354

  20. QENS investigation of filled rubbers

    NASA Astrophysics Data System (ADS)

    Triolo, A.; Lo Celso, F.; Negroni, F.; Arrighi, V.; Qian, H.; Lechner, R. E.; Desmedt, A.; Pieper, J.; Frick, B.; Triolo, R.

    The polymer segmental dynamics is investigated in a series of silica-filled rubbers. The presence of inert fillers in polymers greatly affects the mechanical and physical performance of the final materials. For example, silica has been proposed as a reinforcing agent of elastomers in tire production. Results from quasielastic neutron scattering and Dynamic Mechanical Thermal Analysis (DMTA) measurements are presented on styrene-ran-butadiene rubber filled with silica. A clear indication is obtained of the existence of a bimodal dynamics, which can be rationalized in terms of the relaxation of bulk rubber and the much slower relaxation of the rubber adsorbed on the filler surface.

  1. 244-AR Vault Interim Stabilization Project Plan

    SciTech Connect

    LANEY, T.

    2000-03-24

    The 244-AR Vault Facility, constructed between 1966 and 1968, was designed to provide lag storage and treatment for the Plutonium-Uranium Extraction Facility (PUREX) tank farm sludges. Tank farm personnel transferred the waste from the 244-AR Vault Facility to B Plant for recovery of cesium and strontium. B Plant personnel then transferred the treatment residuals back to the tank farms for storage of the sludge and liquids. The last process operations, which transferred waste supporting the cesium/strontium recovery mission, occurred in April 1978. After the final transfer in 1978, the 244-AR facility underwent a cleanout. However, 2,271 L (600 gal) of sludge were left in Tank 004AR from an earlier transfer from Tank 241-AX-104. When the cleanout was completed, the facility was placed in a standby status. The sludge had been transferred to Tank 004AR to support Pacific Northwest National Laboratory [PNNL] vitrification work. Documentation of waste transfers suggests that a portion of the sludge may have been moved from Tank 004AR to Tank 002AR in preparation for transfer back to the AX Tank Farm; however, quantities of the sludge that were moved to Tank 002AR from that transfer must be estimated.

  2. USDA/ARS Organic Production Research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For much of its history, USDA/ARS had little to do with research on organic agriculture, however research in organic systems has made considerable gains at the agency over the past decade. In the 1980's and 1990's, as the organic food industry was taking off, ARS researchers who wanted to serve orga...

  3. 36Cl-36Ar Exposure Ages of Chondritic Metals

    NASA Astrophysics Data System (ADS)

    Graf, Th.; Caffee, M. W.; Finkel, R. C.; Marti, K.; Nishiizumi, K.; Ponganis, K. V.

    1995-09-01

    Metal separates were prepared to determine ^36Cl-^36Ar exposure ages for six H4 p.m. falls (with reported bulk exposure ages of 4 to 10Ma), for ten H5 a.m. falls (T(sub)e = 4-10 Ma) and for the Acapulco meteorite (T(^36Cl-^36Ar)= 5.7 Ma). This dating method uses production rate ratios P(^36Cl)/P(^36Ar) and is independent of the shielding-sensitive absolute production rates. It is also known that for protons the production rate ratio is rather insensitive to changes in the energy spectrum; the dependence of this ratio for secondary neutrons is at present less understood. First results were already reported [1]. The cosmic-ray-produced ^3He/^38Ar ratios show a bimodal distribution with two clusters at about 15 and about 9 (Fig. 1). About half of the ^3He is produced via ^3H which is known to diffuse in metal at relatively low temperatures. Therefore, Fig. 1 provides evidence for a quasi-continuous loss of ^3H from such metals. If this loss mechanism is due to solar heating, perihelia <1 AU are indicated for these meteorites. Losses are prominent for H5 a.m. falls, but not for H4 p.m. falls. The orbital implications are consistent with those already known from the time-of-fall parameter (p.m. falls / total falls) which was used in the selection of the H4,H5 sample sets [2]. The exposure age histograms of both H groups show the well known clusters at about 7 Ma. The width of the exposure age peaks differ, however, and the collisional break-up event can be further constrained. Except for Nassirah, all members of the H4 p.m. group fall into the range 7.0 +/- 0.3 Ma. Bulk rock ages (8.2-9.3 Ma) [3] as well as the ^36Cl-^36Ar age (8.3 Ma) of Nassirah are higher and may indicate that this meteorite does not belong to the collisional event. We observe a small but systematic difference in calculated exposure ages by the ^36Cl-^36Ar method, when compared with ages obtained by conventional noble gas production rates. This shift (about 10%) does not appear to be dependent on

  4. Noble gases solubility models of hydrocarbon charge mechanism in the Sleipner Vest gas field

    NASA Astrophysics Data System (ADS)

    Barry, P. H.; Lawson, M.; Meurer, W. P.; Warr, O.; Mabry, J. C.; Byrne, D. J.; Ballentine, C. J.

    2016-12-01

    Noble gases are chemically inert and variably soluble in crustal fluids. They are primarily introduced into hydrocarbon reservoirs through exchange with formation waters, and can be used to assess migration pathways and mechanisms, as well as reservoir storage conditions. Of particular interest is the role groundwater plays in hydrocarbon transport, which is reflected in hydrocarbon-water volume ratios. Here, we present compositional, stable isotope and noble gas isotope and abundance data from the Sleipner Vest field, in the Norwegian North Sea. Sleipner Vest gases are generated from primary cracking of kerogen and the thermal cracking of oil. Gas was emplaced into the Sleipner Vest from the south and subsequently migrated to the east, filling and spilling into the Sleipner Ost fields. Gases principally consist of hydrocarbons (83-93%), CO2 (5.4-15.3%) and N2 (0.6-0.9%), as well as trace concentrations of noble gases. Helium isotopes (3He/4He) are predominantly radiogenic and range from 0.065 to 0.116 RA; reported relative to air (RA = 1.4 × 10-6; Clarke et al., 1976; Sano et al., 1988), showing predominantly (>98%) crustal contributions, consistent with Ne (20Ne/22Ne from 9.70 to 9.91; 21Ne/22Ne from 0.0290 to 0.0344) and Ar isotopes (40Ar/36Ar from 315 to 489). Air-derived noble gas isotopes (20Ne, 36Ar, 84Kr, 132Xe) are introduced into the hydrocarbon system by direct exchange with air-saturated water (ASW). The distribution of air-derived noble gas species are controlled by phase partitioning processes; in that they preferentially partition into the gas (i.e., methane) phase, due to their low solubilities in fluids. Therefore, the extent of exchange between hydrocarbon phases and formation waters - that have previously equilibrated with the atmosphere - can be determined by investigating air-derived noble gas species. We utilize both elemental ratios to address process (i.e., open vs. closed system) and concentrations to quantify the extent of hydrocarbon

  5. Aging Studies of Filled and Unfilled VCE

    SciTech Connect

    Letant, S; Herberg, J; Alviso, C; Small, W; Mulcahy, H; Pearson, M; Wilson, T; Chinn, S; Maxwell, R

    2009-11-10

    This report presents data on the effects of temperature and gamma radiation on the chemical and structural properties of both filled and unfilled VCE material produced by the Kansas City Plant using WR-qualified processes. Thermal effects up to 300 C and gamma irradiation doses of 1 MRad and 25 MRad were investigated under atmospheric conditions. Characterization techniques used in the study comprise Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Tensile Testing, Solid Phase MicroExtraction - Gas Chromatography/Mass Spectrometry (SPME-GC/MS), phenol extraction followed by HPLC, and various Nuclear Magnetic Resonance (NMR) techniques including: {sup 13}C, {sup 13}C {l_brace}{sup 1}H{r_brace} cross polarization (CP), {sup 1}H magic angle spinning (MAS), 13C{l_brace}{sup 1}H{r_brace} Wide-line-Separation (2D-WISE) and development of Center band-Only Detection of Exchange (CODEX).

  6. Apparatus for determining the filling pressure of a plurality of microballoons

    DOEpatents

    Jorgensen, Betty S.

    1987-01-01

    A simple apparatus for removably holding a plurality of microballoons during filling and determination of the pressure of the gas fill. The subject apparatus permits the manipulation of substantial numbers of microballoons necessary for the rapidly growing requirements for these capsules.

  7. The B AB AR detector

    NASA Astrophysics Data System (ADS)

    Aubert, B.; Bazan, A.; Boucham, A.; Boutigny, D.; De Bonis, I.; Favier, J.; Gaillard, J.-M.; Jeremie, A.; Karyotakis, Y.; Le Flour, T.; Lees, J. P.; Lieunard, S.; Petitpas, P.; Robbe, P.; Tisserand, V.; Zachariadou, K.; Palano, A.; Chen, G. P.; Chen, J. C.; Qi, N. D.; Rong, G.; Wang, P.; Zhu, Y. S.; Eigen, G.; Reinertsen, P. L.; Stugu, B.; Abbott, B.; Abrams, G. S.; Amerman, L.; Borgland, A. W.; Breon, A. B.; Brown, D. N.; Button-Shafer, J.; Clark, A. R.; Dardin, S.; Day, C.; Dow, S. F.; Fan, Q.; Gaponenko, I.; Gill, M. S.; Goozen, F. R.; Gowdy, S. J.; Gritsan, A.; Groysman, Y.; Hernikl, C.; Jacobsen, R. G.; Jared, R. C.; Kadel, R. W.; Kadyk, J.; Karcher, A.; Kerth, L. T.; Kipnis, I.; Kluth, S.; Kral, J. F.; Lafever, R.; LeClerc, C.; Levi, M. E.; Lewis, S. A.; Lionberger, C.; Liu, T.; Long, M.; Luo, L.; Lynch, G.; Luft, P.; Mandelli, E.; Marino, M.; Marks, K.; Matuk, C.; Meyer, A. B.; Minor, R.; Mokhtarani, A.; Momayezi, M.; Nyman, M.; Oddone, P. J.; Ohnemus, J.; Oshatz, D.; Patton, S.; Pedrali-Noy, M.; Perazzo, A.; Peters, C.; Pope, W.; Pripstein, M.; Quarrie, D. R.; Rasson, J. E.; Roe, N. A.; Romosan, A.; Ronan, M. T.; Shelkov, V. G.; Stone, R.; Strother, P. D.; Telnov, A. V.; von der Lippe, H.; Weber, T. F.; Wenzel, W. A.; Zizka, G.; Bright-Thomas, P. G.; Hawkes, C. M.; Kirk, A.; Knowles, D. J.; O'Neale, S. W.; Watson, A. T.; Watson, N. K.; Deppermann, T.; Koch, H.; Krug, J.; Kunze, M.; Lewandowski, B.; Peters, K.; Schmuecker, H.; Steinke, M.; Andress, J. C.; Barlow, N. R.; Bhimji, W.; Chevalier, N.; Clark, P. J.; Cottingham, W. N.; De Groot, N.; Dyce, N.; Foster, B.; Mass, A.; McFall, J. D.; Wallom, D.; Wilson, F. F.; Abe, K.; Hearty, C.; McKenna, J. A.; Thiessen, D.; Camanzi, B.; Harrison, T. J.; McKemey, A. K.; Tinslay, J.; Antohin, E. I.; Blinov, V. E.; Bukin, A. D.; Bukin, D. A.; Buzykaev, A. R.; Dubrovin, M. S.; Golubev, V. B.; Ivanchenko, V. N.; Kolachev, G. M.; Korol, A. A.; Kravchenko, E. A.; Mikhailov, S. F.; Onuchin, A. P.; Salnikov, A. A.; Serednyakov, S. I.; Skovpen, Yu. I.; Telnov, V. I.; Yushkov, A. N.; Booth, J.; Lankford, A. J.; Mandelkern, M.; Pier, S.; Stoker, D. P.; Zioulas, G.; Ahsan, A.; Arisaka, K.; Buchanan, C.; Chun, S.; Faccini, R.; MacFarlane, D. B.; Prell, S. A.; Rahatlou, Sh.; Raven, G.; Sharma, V.; Burke, S.; Callahan, D.; Campagnari, C.; Dahmes, B.; Hale, D.; Hart, P. A.; Kuznetsova, N.; Kyre, S.; Levy, S. L.; Long, O.; Lu, A.; May, J.; Richman, J. D.; Verkerke, W.; Witherell, M.; Yellin, S.; Beringer, J.; DeWitt, J.; Dorfan, D. E.; Eisner, A. M.; Frey, A.; Grillo, A. A.; Grothe, M.; Heusch, C. A.; Johnson, R. P.; Kroeger, W.; Lockman, W. S.; Pulliam, T.; Rowe, W.; Sadrozinski, H.; Schalk, T.; Schmitz, R. E.; Schumm, B. A.; Seiden, A.; Spencer, E. N.; Turri, M.; Walkowiak, W.; Wilder, M.; Williams, D. C.; Chen, E.; Dubois-Felsmann, G. P.; Dvoretskii, A.; Hanson, J. E.; Hitlin, D. G.; Kolomensky, Yu. G.; Metzler, S.; Oyang, J.; Porter, F. C.; Ryd, A.; Samuel, A.; Weaver, M.; Yang, S.; Zhu, R. Y.; Devmal, S.; Geld, T. L.; Jayatilleke, S.; Jayatilleke, S. M.; Mancinelli, G.; Meadows, B. T.; Sokoloff, M. D.; Bloom, P.; Broomer, B.; Erdos, E.; Fahey, S.; Ford, W. T.; Gaede, F.; van Hoek, W. C.; Johnson, D. R.; Michael, A. K.; Nauenberg, U.; Olivas, A.; Park, H.; Rankin, P.; Roy, J.; Sen, S.; Smith, J. G.; Wagner, D. L.; Blouw, J.; Harton, J. L.; Krishnamurthy, M.; Soffer, A.; Toki, W. H.; Warner, D. W.; Wilson, R. J.; Zhang, J.; Brandt, T.; Brose, J.; Dahlinger, G.; Dickopp, M.; Dubitzky, R. S.; Eckstein, P.; Futterschneider, H.; Kocian, M. L.; Krause, R.; Müller-Pfefferkorn, R.; Schubert, K. R.; Schwierz, R.; Spaan, B.; Wilden, L.; Behr, L.; Bernard, D.; Bonneaud, G. R.; Brochard, F.; Cohen-Tanugi, J.; Ferrag, S.; Fouque, G.; Gastaldi, F.; Matricon, P.; Mora de Freitas, P.; Renard, C.; Roussot, E.; T'Jampens, S.; Thiebaux, C.; Vasileiadis, G.; Verderi, M.; Anjomshoaa, A.; Bernet, R.; Di Lodovico, F.; Muheim, F.; Playfer, S.; Swain, J. E.; Falbo, M.; Bozzi, C.; Dittongo, S.; Folegani, M.; Piemontese, L.; Ramusino, A. C.; Treadwell, E.; Anulli, F.; Baldini-Ferroli, R.; Calcaterra, A.; de Sangro, R.; Falciai, D.; Finocchiaro, G.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Xie, Y.; Zallo, A.; Bagnasco, S.; Buzzo, A.; Contri, R.; Crosetti, G.; Fabbricatore, P.; Farinon, S.; Lo Vetere, M.; Macri, M.; Minutoli, S.; Monge, M. R.; Musenich, R.; Pallavicini, M.; Parodi, R.; Passaggio, S.; Pastore, F. C.; Patrignani, C.; Pia, M. G.; Priano, C.; Robutti, E.; Santroni, A.; Bartoldus, R.; Dignan, T.; Hamilton, R.; Mallik, U.; Cochran, J.; Crawley, H. B.; Fischer, P. A.; Lamsa, J.; McKay, R.; Meyer, W. T.; Rosenberg, E. I.; Albert, J. N.; Beigbeder, C.; Benkebil, M.; Breton, D.; Cizeron, R.; Du, S.; Grosdidier, G.; Hast, C.; Höcker, A.; Lacker, H. M.; LePeltier, V.; Lutz, A. M.; Plaszczynski, S.; Schune, M. H.; Trincaz-Duvoid, S.; Truong, K.; Valassi, A.; Wormser, G.; Alford, O.; Behne, D.; Bionta, R. M.; Bowman, J.; Brigljević, V.; Brooks, A.; Dacosta, V. A.; Fackler, O.; Fujino, D.; Harper, M.; Lange, D. J.; Mugge, M.; O'Connor, T. G.; Olson, H.; Ott, L.; Parker, E.; Pedrotti, B.; Roeben, M.; Shi, X.; van Bibber, K.; Wenaus, T. J.; Wright, D. M.; Wuest, C. R.; Yamamoto, B.; Carroll, M.; Cooke, P.; Fry, J. R.; Gabathuler, E.; Gamet, R.; George, M.; Kay, M.; McMahon, S.; Muir, A.; Payne, D. J.; Sloane, R. J.; Sutcliffe, P.; Touramanis, C.; Aspinwall, M. L.; Bowerman, D. A.; Dauncey, P. D.; Eschrich, I.; Gunawardane, N. J. W.; Martin, R.; Nash, J. A.; Price, D. R.; Sanders, P.; Smith, D.; Azzopardi, D. E.; Back, J. J.; Dixon, P.; Harrison, P. F.; Newman-Coburn, D.; Potter, R. J. L.; Shorthouse, H. W.; Williams, M. I.; Vidal, P. B.; Cowan, G.; George, S.; Green, M. G.; Kurup, A.; Marker, C. E.; McGrath, P.; McMahon, T. R.; Salvatore, F.; Scott, I.; Vaitsas, G.; Brown, D.; Davis, C. L.; Li, Y.; Pavlovich, J.; Allison, J.; Barlow, R. J.; Boyd, J. T.; Fullwood, J.; Jackson, F.; Khan, A.; Lafferty, G. D.; Savvas, N.; Simopoulos, E. T.; Thompson, R. J.; Weatherall, J. H.; Bard, R.; Dallapiccola, C.; Farbin, A.; Jawahery, A.; Lillard, V.; Olsen, J.; Roberts, D. A.; Schieck, J. R.; Blaylock, G.; Flood, K. T.; Hertzbach, S. S.; Kofler, R.; Lin, C. S.; Willocq, S.; Wittlin, J.; Brau, B.; Cowan, R.; Taylor, F.; Yamamoto, R. K.; Britton, D. I.; Fernholz, R.; Houde, M.; Milek, M.; Patel, P. M.; Trischuk, J.; Lanni, F.; Palombo, F.; Bauer, J. M.; Booke, M.; Cremaldi, L.; Kroeger, R.; Reep, M.; Reidy, J.; Sanders, D. A.; Summers, D. J.; Arguin, J. F.; Beaulieu, M.; Martin, J. P.; Nief, J. Y.; Seitz, R.; Taras, P.; Woch, A.; Zacek, V.; Nicholson, H.; Sutton, C. S.; Cartaro, C.; Cavallo, N.; De Nardo, G.; Fabozzi, F.; Gatto, C.; Lista, L.; Piccolo, D.; Sciacca, C.; Cason, N. M.; LoSecco, J. M.; Alsmiller, J. R. G.; Gabriel, T. A.; Handler, T.; Heck, J.; Iwasaki, M.; Sinev, N. B.; Caracciolo, R.; Colecchia, F.; Dal Corso, F.; Galeazzi, F.; Marzolla, M.; Michelon, G.; Morandin, M.; Posocco, M.; Rotondo, M.; Santi, S.; Simonetto, F.; Stroili, R.; Torassa, E.; Voci, C.; Bailly, P.; Benayoun, M.; Briand, H.; Chauveau, J.; David, P.; De la Vaissière, C.; Del Buono, L.; Genat, J.-F.; Hamon, O.; Leruste, Ph.; Le Diberder, F.; Lebbolo, H.; Lory, J.; Martin, L.; Martinez-Vidal, F.; Roos, L.; Stark, J.; Versillé, S.; Zhang, B.; Manfredi, P. F.; Ratti, L.; Re, V.; Speziali, V.; Frank, E. D.; Gladney, L.; Guo, Q. H.; Panetta, J. H.; Angelini, C.; Batignani, G.; Bettarini, S.; Bondioli, M.; Bosi, F.; Carpinelli, M.; Forti, F.; Gaddi, A.; Gagliardi, D.; Giorgi, M. A.; Lusiani, A.; Mammini, P.; Morganti, M.; Morsani, F.; Neri, N.; Profeti, A.; Paoloni, E.; Raffaelli, F.; Rama, M.; Rizzo, G.; Sandrelli, F.; Simi, G.; Triggiani, G.; Haire, M.; Judd, D.; Paick, K.; Turnbull, L.; Wagoner, D. E.; Albert, J.; Bula, C.; Kelsey, M. H.; Lu, C.; McDonald, K. T.; Miftakov, V.; Sands, B.; Schaffner, S. F.; Smith, A. J. S.; Tumanov, A.; Varnes, E. W.; Bronzini, F.; Buccheri, A.; Bulfon, C.; Cavoto, G.; del Re, D.; Ferrarotto, F.; Ferroni, F.; Fratini, K.; Lamanna, E.; Leonardi, E.; Mazzoni, M. A.; Morganti, S.; Piredda, G.; Safai Tehrani, F.; Serra, M.; Voena, C.; Waldi, R.; Jacques, P. F.; Kalelkar, M.; Plano, R. J.; Adye, T.; Claxton, B.; Dowdell, J.; Egede, U.; Franek, B.; Galagedera, S.; Geddes, N. I.; Gopal, G. P.; Kay, J.; Lidbury, J.; Madani, S.; Metcalfe, S.; Metcalfe, S.; Markey, G.; Olley, P.; Watt, M.; Xella, S. M.; Aleksan, R.; Besson, P.; Bourgeois, P.; Convert, P.; De Domenico, G.; de Lesquen, A.; Emery, S.; Gaidot, A.; Ganzhur, S. F.; Georgette, Z.; Gosset, L.; Graffin, P.; Hamel de Monchenault, G.; Hervé, S.; Karolak, M.; Kozanecki, W.; Langer, M.; London, G. W.; Marques, V.; Mayer, B.; Micout, P.; Mols, J. P.; Mouly, J. P.; Penichot, Y.; Rolquin, J.; Serfass, B.; Toussaint, J. C.; Usseglio, M.; Vasseur, G.; Yeche, C.; Zito, M.; Copty, N.; Purohit, M. V.; Yumiceva, F. X.; Adam, I.; Adesanya, A.; Anthony, P. L.; Aston, D.; Bartelt, J.; Becla, J.; Bell, R.; Bloom, E.; Boeheim, C. T.; Boyarski, A. M.; Boyce, R. F.; Briggs, D.; Bulos, F.; Burgess, W.; Byers, B.; Calderini, G.; Chestnut, R.; Claus, R.; Convery, M. R.; Coombes, R.; Cottrell, L.; Coupal, D. P.; Coward, D. H.; Craddock, W. W.; DeBarger, S.; DeStaebler, H.; Dorfan, J.; Doser, M.; Dunwoodie, W.; Dusatko, J. E.; Ecklund, S.; Fieguth, T. H.; Freytag, D. R.; Glanzman, T.; Godfrey, G. L.; Haller, G.; Hanushevsky, A.; Harris, J.; Hasan, A.; Hee, C.; Himel, T.; Huffer, M. E.; Hung, T.; Innes, W. R.; Jessop, C. P.; Kawahara, H.; Keller, L.; King, M. E.; Klaisner, L.; Krebs, H. J.; Langenegger, U.; Langeveld, W.; Leith, D. W. G. S.; Louie, S. K.; Luitz, S.; Luth, V.; Lynch, H. L.; McDonald, J.; Manzin, G.; Marsiske, H.; Mattison, T.; McCulloch, M.; McDougald, M.; McShurley, D.; Menke, S.; Messner, R.; Metcalfe, S.; Morii, M.; Mount, R.; Muller, D. R.; Nelson, D.; Nordby, M.; O'Grady, C. P.; Olavson, L.; Olsen, J.; O'Neill, F. G.; Oxoby, G.; Paolucci, P.; Pavel, T.; Perl, J.; Pertsova, M.; Petrak, S.; Putallaz, G.; Raines, P. E.; Ratcliff, B. N.; Reif, R.; Robertson, S. H.; Rochester, L. S.; Roodman, A.; Russel, J. J.; Sapozhnikov, L.; Saxton, O. H.; Schietinger, T.; Schindler, R. H.; Schwiening, J.; Sciolla, G.; Seeman, J. T.; Serbo, V. V.; Shapiro, S.; Skarpass, K., Sr.; Snyder, A.; Soderstrom, E.; Soha, A.; Spanier, S. M.; Stahl, A.; Stiles, P.; Su, D.; Sullivan, M. K.; Talby, M.; Tanaka, H. A.; Va'vra, J.; Wagner, S. R.; Wang, R.; Weber, T.; Weinstein, A. J. R.; White, J. L.; Wienands, U.; Wisniewski, W. J.; Young, C. C.; Yu, N.; Burchat, P. R.; Cheng, C. H.; Kirkby, D.; Meyer, T. I.; Roat, C.; Henderson, R.; Khan, N.; Berridge, S.; Bugg, W.; Cohn, H.; Hart, E.; Weidemann, A. W.; Benninger, T.; Izen, J. M.; Kitayama, I.; Lou, X. C.; Turcotte, M.; Bianchi, F.; Bona, M.; Daudo, F.; Di Girolamo, B.; Gamba, D.; Grosso, P.; Smol, A.; Trapani, P. P.; Zanin, D.; Bosisio, L.; Della Ricca, G.; Lanceri, L.; Pompili, A.; Poropat, P.; Prest, M.; Rashevskaia, I.; Vallazza, E.; Vuagnin, G.; Panvini, R. S.; Brown, C.; De Silva, A.; Kowalewski, R.; Pitman, D.; Roney, J. M.; Band, H. R.; Charles, E.; Dasu, S.; Elmer, P.; Johnson, J. R.; Nielsen, J.; Orejudos, W.; Pan, Y.; Prepost, R.; Scott, I. J.; Walsh, J.; Wu, S. L.; Yu, Z.; Zobernig, H.; Moore, T. B.; Neal, H.

    2002-02-01

    B AB AR, the detector for the SLAC PEP-II asymmetric e +e - B Factory operating at the ϒ(4 S) resonance, was designed to allow comprehensive studies of CP-violation in B-meson decays. Charged particle tracks are measured in a multi-layer silicon vertex tracker surrounded by a cylindrical wire drift chamber. Electromagnetic showers from electrons and photons are detected in an array of CsI crystals located just inside the solenoidal coil of a superconducting magnet. Muons and neutral hadrons are identified by arrays of resistive plate chambers inserted into gaps in the steel flux return of the magnet. Charged hadrons are identified by d E/d x measurements in the tracking detectors and by a ring-imaging Cherenkov detector surrounding the drift chamber. The trigger, data acquisition and data-monitoring systems, VME- and network-based, are controlled by custom-designed online software. Details of the layout and performance of the detector components and their associated electronics and software are presented.

  8. Can-Filled Crash Barrier

    NASA Technical Reports Server (NTRS)

    Wilson, A. H.

    1983-01-01

    Crash barrier composed largely of used aluminum beverage cans protects occupants of cars in collisions with poles or trees. Lightweight, can-filled barrier very effective in softening impact of an automobile in head-on and off-angle collisions. Preliminary results indicate barrier is effective in collisions up to 40 mi/h (64 km/h).

  9. Filling in the retinal image

    NASA Technical Reports Server (NTRS)

    Larimer, James; Piantanida, Thomas

    1990-01-01

    The optics of the eye form an image on a surface at the back of the eyeball called the retina. The retina contains the photoreceptors that sample the image and convert it into a neural signal. The spacing of the photoreceptors in the retina is not uniform and varies with retinal locus. The central retinal field, called the macula, is densely packed with photoreceptors. The packing density falls off rapidly as a function of retinal eccentricity with respect to the macular region and there are regions in which there are no photoreceptors at all. The retinal regions without photoreceptors are called blind spots or scotomas. The neural transformations which convert retinal image signals into percepts fills in the gaps and regularizes the inhomogeneities of the retinal photoreceptor sampling mosaic. The filling-in mechamism plays an important role in understanding visual performance. The filling-in mechanism is not well understood. A systematic collaborative research program at the Ames Research Center and SRI in Menlo Park, California, was designed to explore this mechanism. It was shown that the perceived fields which are in fact different from the image on the retina due to filling-in, control some aspects of performance and not others. Researchers have linked these mechanisms to putative mechanisms of color coding and color constancy.

  10. Unsteady Capillary Filling By Electrocapillarity

    NASA Astrophysics Data System (ADS)

    Kang, In Seok; Lee, Jung A.

    2016-11-01

    Unsteady filling of electrolyte solution inside a nanochannel by the electrocapillarity effect is studied. The filling rate is predicted as a function of the bulk concentration of the electrolyte, the surface potential (or surface charge density), and the cross sectional shape of the channel. Since the driving force of the flow is the electrocapillarity, it is first analyzed by using the solution of the Poisson-Boltzmann equation. From the analysis, it is found that the results for many different cross sectional shapes can be unified with good accuracy if the hydraulic radius is adopted as the characteristic length scale of the problem. Especially in the case of constant surface potential, for both limits of κh -> 0 and κh -> ∞ , it can be shown theoretically that the electrocapillarity is independent of the cross sectional shape if the hydraulic radius is the same. In order to analyze the geometric effects more systematically, we consider the regular N-polygons with the same hydraulic radius and the rectangles of different aspect ratios. Washburn's approach is then adopted to predict the filling rate of electrolyte solution inside a nanaochannel. It is found that the average filling velocity decreases as N increases in the case of regular N-polygons with the same hydraulic radius. This is because of that the regular N-polygons of the same hydraulic radius share the same inscribing circle. This work has been supported by BK21+ program.

  11. 40Ar/39Ar and K-Ar data bearing on the metamorphic and tectonic history of western New England.

    USGS Publications Warehouse

    Sutter, J.F.; Ratcliffe, N.M.; Mukasa, S.B.

    1985-01-01

    40Ar/39Ar ages of coexisting biotite and hornblende from Proterozoic Y gneisses of the Berkshire and Green Mt massifs, as well as 40Ar/39Ar and K/Ar mineral and whole-rock ages from Palaeozoic metamorphic rocks, suggest that the thermal peaks for the dominant metamorphic recrystallization in western New England occurred 465 + or - 5 m.y. (Taconian). 40Ar/39Ar age data from a poorly-defined terrain along the eastern strip of the area suggests that the area has been retrograded during a metamorphism that peaked at least 376 + or - 5 m.y. (Acadian). Available age and petrological data from western New England indicate the presence of at least three separate metamorphic-structure domains of Taconic age: 1) a small area of relict high-P and low-T metamorphism, 2) a broad area of normal Barrovian metamorphism from chlorite to garnet grade characterized by a gentle metamorphic gradient and, 3) a rather narrow belt of steep-gradient, Barrovian series metamorphic rocks. Areas of maximum metamorphic intensity within the last domain coincide with areas of maximum crustal thickening in the later stage of Taconic orogeny. -L.di H

  12. Engine component improvement: Performance improvement, JT9D-7 3.8 AR fan

    NASA Technical Reports Server (NTRS)

    Gaffin, W. O.

    1980-01-01

    A redesigned, fuel efficient fan for the JT9D-7 engine was tested. Tests were conducted to determine the effect of the 3.8 AR fan on performance, stability, operational characteristics, and noise of the JT9D-7 engine relative to the current 4.6 AR Bill-of-Material fan. The 3.8 AR fan provides increased fan efficiency due to a more advanced blade airfoil with increased chord, eliminating one part span shroud and reducing the number of fan blades and fan exit guide vanes. Engine testing at simulated cruise conditions demonstrated the predicted 1.3 percent improvement in specific fuel consumption with the redesigned 3.8 AR fan. Flight testing and sea level stand engine testing demonstrated exhaust gas temperature margins, fan and low pressure compressor stability, operational suitability, and noise levels comparable to the Bill-of-Material fan.

  13. Photomask cleaning process improvement to minimize ArF haze

    NASA Astrophysics Data System (ADS)

    Graham, Michael; McDonald, Andrew

    2008-04-01

    Growth of "haze" defects on photomasks exposed in ArF lithography is recognized as a serious problem. Haze defects that have grown to detectable sizes can be analysed in situ by techniques such as EDX or Raman, but to analyze at the photomask manufacturing stage requires extraction of residues by solution in DI water. The effect of extraction conditions, including surface area and material, water volume, time, and temperature, has been studied. A standard method to compare residual ion levels is proposed. Various methods for reducing residual ion levels from the photomask cleaning process have been published. These include SPM reduction, oxygen plasma, SC1 dilution, Megasonic agitation, hot rinse, UV exposure, thermal bake, ozone water, ozone gas, and hydrogenated water. Critical parameters for the cleaning process, besides residual ion levels and contamination removal efficiency, include CD shift, AR/chrome damage, scatter bar damage, and on phase shift masks, the change in phase and transmission. An optimized process combining conventional and novel techniques is described. Data is presented to show the importance of controlling all resist strip and clean processes, not just the final clean. It has achieved sulphate levels of 0.2ng/cm2 (well below the critical level for haze growth), as well as improved results for the other critical parameters. This process has been demonstrated to allow ArF exposure of large numbers of wafers without the appearance of haze defects.

  14. Calibration of an Ultra-Low-Background Proportional Counter for Measuring 37Ar

    SciTech Connect

    Seifert, Allen; Aalseth, Craig E.; Bonicalzi, Ricco; Bowyer, Ted W.; Day, Anthony R.; Fuller, Erin S.; Haas, Derek A.; Hayes, James C.; Hoppe, Eric W.; Humble, Paul H.; Keillor, Martin E.; LaFerriere, Brian D.; Mace, Emily K.; McIntyre, Justin I.; Merriman, Jason H.; Miley, Harry S.; Myers, Allan W.; Orrell, John L.; Overman, Cory T.; Panisko, Mark E.; Williams, Richard M.

    2013-08-08

    Abstract. An ultra-low-background proportional counter (ULBPC) design has been developed at Pacific Northwest National Laboratory (PNNL) using clean materials, primarily electrochemically-purified copper. This detector, along with an ultra-low-background counting system (ULBCS), was developed to complement a new shallow underground laboratory (30 meters water-equivalent) constructed at PNNL. The ULBCS design includes passive neutron and gamma shielding, along with an active cosmic-veto system. This system provides a capability for making ultra-sensitive measurements to support applications like age-dating soil hydrocarbons with 14C/3H, age-dating of groundwater with 39Ar, and soil-gas assay for 37Ar to support On-Site Inspection (OSI). On-Site Inspection is a key component of the verification regime for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Measurements of radionuclides created by an underground nuclear explosion are valuable signatures of a Treaty violation. For OSI, the 35-day half-life of 37Ar, produced from neutron interactions with calcium in soil, provides both high specific activity and sufficient time for inspection before decay limits sensitivity. This work describes the calibration techniques and analysis methods developed to enable quantitative measurements of 37Ar samples over a broad range of pressures. These efforts, along with parallel work in progress on gas chemistry separation, are expected to provide a significant new capability for 37Ar soil gas background studies.

  15. Calibration of an ultra-low-background proportional counter for measuring {sup 37}Ar

    SciTech Connect

    Seifert, A.; Aalseth, C. E.; Bonicalzi, R. M.; Bowyer, T. W.; Day, A. R.; Fuller, E. S.; Haas, D. A.; Hayes, J. C.; Hoppe, E. W.; Humble, P. H.; Keillor, M. E.; LaFerriere, B. D.; Mace, E. K.; McIntyre, J. I.; Merriman, J. H.; Miley, H. S.; Myers, A. W.; Orrell, J. L.; Overman, C. T.; Panisko, M. E.; and others

    2013-08-08

    An ultra-low-background proportional counter design has been developed at Pacific Northwest National Laboratory (PNNL) using clean materials, primarily electro-chemically-purified copper. This detector, along with an ultra-low-background counting system (ULBCS), was developed to complement a new shallow underground laboratory (30 meters water-equivalent) at PNNL. The ULBCS design includes passive neutron and gamma shielding, along with an active cosmic-veto system. This system provides a capability for making ultra-sensitive measurements to support applications like age-dating soil hydrocarbons with {sup 14}C/{sup 3}H, age-dating of groundwater with {sup 39}Ar, and soil-gas assay for {sup 37}Ar to support On-Site Inspection (OSI). On-Site Inspection is a key component of the verification regime for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Measurements of radionuclides created by an underground nuclear explosion are valuable signatures of a Treaty violation. For OSI, the 35-day half-life of {sup 37}Ar, produced from neutron interactions with calcium in soil, provides both high specific activity and sufficient time for inspection before decay limits sensitivity. This work describes the calibration techniques and analysis methods developed to enable quantitative measurements of {sup 37}Ar samples over a broad range of proportional counter operating pressures. These efforts, along with parallel work in progress on gas chemistry separation, are expected to provide a significant new capability for {sup 37}Ar soil gas background studies.

  16. Calibration of an ultra-low-background proportional counter for measuring 37Ar

    NASA Astrophysics Data System (ADS)

    Seifert, A.; Aalseth, C. E.; Bonicalzi, R. M.; Bowyer, T. W.; Day, A. R.; Fuller, E. S.; Haas, D. A.; Hayes, J. C.; Hoppe, E. W.; Humble, P. H.; Keillor, M. E.; LaFerriere, B. D.; Mace, E. K.; McIntyre, J. I.; Merriman, J. H.; Miley, H. S.; Myers, A. W.; Orrell, J. L.; Overman, C. T.; Panisko, M. E.; Williams, R. M.

    2013-08-01

    An ultra-low-background proportional counter design has been developed at Pacific Northwest National Laboratory (PNNL) using clean materials, primarily electro-chemically-purified copper. This detector, along with an ultra-low-background counting system (ULBCS), was developed to complement a new shallow underground laboratory (30 meters water-equivalent) at PNNL. The ULBCS design includes passive neutron and gamma shielding, along with an active cosmic-veto system. This system provides a capability for making ultra-sensitive measurements to support applications like age-dating soil hydrocarbons with 14C/3H, age-dating of groundwater with 39Ar, and soil-gas assay for 37Ar to support On-Site Inspection (OSI). On-Site Inspection is a key component of the verification regime for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Measurements of radionuclides created by an underground nuclear explosion are valuable signatures of a Treaty violation. For OSI, the 35-day half-life of 37Ar, produced from neutron interactions with calcium in soil, provides both high specific activity and sufficient time for inspection before decay limits sensitivity. This work describes the calibration techniques and analysis methods developed to enable quantitative measurements of 37Ar samples over a broad range of proportional counter operating pressures. These efforts, along with parallel work in progress on gas chemistry separation, are expected to provide a significant new capability for 37Ar soil gas background studies.

  17. 40Ar/39Ar ages of lunar impact glasses: Relationships among Ar diffusivity, chemical composition, shape, and size

    NASA Astrophysics Data System (ADS)

    Zellner, N. E. B.; Delano, J. W.

    2015-07-01

    Lunar impact glasses, which are quenched melts produced during cratering events on the Moon, have the potential to provide not only compositional information about both the local and regional geology of the Moon but also information about the impact flux over time. We present in this paper the results of 73 new 40Ar/39Ar analyses of well-characterized, inclusion-free lunar impact glasses and demonstrate that size, shape, chemical composition, fraction of radiogenic 40Ar retained, and cosmic ray exposure (CRE) ages are important for 40Ar/39Ar investigations of these samples. Specifically, analyses of lunar impact glasses from the Apollo 14, 16, and 17 landing sites indicate that retention of radiogenic 40Ar is a strong function of post-formation thermal history in the lunar regolith, size, and chemical composition. This is because the Ar diffusion coefficient (at a constant temperature) is estimated to decrease by ∼3-4 orders of magnitude with an increasing fraction of non-bridging oxygens, X(NBO), over the compositional range of most lunar impact glasses with compositions from feldspathic to basaltic. Based on these relationships, lunar impact glasses with compositions and sizes sufficient to have retained ∼90% of their radiogenic Ar during 750 Ma of cosmic ray exposure at time-integrated temperatures of up to 290 K have been identified and are likely to have yielded reliable 40Ar/39Ar ages of formation. Additionally, ∼50% of the identified impact glass spheres have formation ages of ⩽500 Ma, while ∼75% of the identified lunar impact glass shards and spheres have ages of formation ⩽2000 Ma. Higher thermal stresses in lunar impact glasses quenched from hyperliquidus temperatures are considered the likely cause of poor survival of impact glass spheres, as well as the decreasing frequency of lunar impact glasses in general with increasing age. The observed age-frequency distribution of lunar impact glasses may reflect two processes: (i) diminished

  18. 40Ar/39Ar Ages of Carbonaceous Xenoliths in 2 HED Meteorites

    NASA Technical Reports Server (NTRS)

    Turrin, B.; Lindsay, F. N.; Park, J.; Herzog, G. F.; Delaney, J. S.; Swisher, C. C., III; Johnson, J.; Zolensky, M.

    2016-01-01

    The generally young K/Ar and 40Ar/39Ar ages of CM chondrites made us wonder whether carbonaceous xenoliths (CMX) entombed in Howardite–Eucrite–Diogenite (HED) meteorites might retain more radiogenic 40Ar than do ‘free-range’ CM-chondrites. To find out, we selected two HED breccias with carbonaceous inclusions in order to compare the 40Ar/39Ar release patterns and ages of the inclusions with those of nearby HED material. Carbonaceous inclusions (CMXs) in two HED meteorites lost a greater fraction of radiogenic 40Ar than did surrounding host material, but a smaller fraction of it than did free-range CM-chondrites such as Murchison or more heavily altered ones. Importantly, however, the siting of the CMXs in HED matrix did not prevent the 40Ar loss of about 40 percent of the radiogenic 40Ar, even from phases that degas at high laboratory temperatures. We infer that carbonaceous asteroids with perihelia of 1 astronomical unit probably experience losses of at least this size. The usefulness of 40Ar/39Ar dating for samples returned from C-type asteroids may hinge, therefore, on identifying and analyzing separately small quantities of the most retentive phases of carbonaceous chondrites.

  19. Ar-40/Ar-39 laser-probe dating of diamond inclusions from the Premier kimberlite

    NASA Technical Reports Server (NTRS)

    Phillips, D.; Onstott, T. C.; Harris, J. W.

    1989-01-01

    The results of Ar-40/Ar-39 laser-probe analyses of individual eclogitic clinopyroxene inclusions from Premier diamonds are reported which yield a mean age of 1198 + or - 14 Myr. This age agrees well with Sm-Nd and Ar-40/Ar-39 analyses on similar Premier inclusions and is indistinguishable from the inferred time of emplacement of the host kimberlite, which implies that diamond formation was essentially synchronous with kimberlite generation. The extrapolated nonradiogenic Ar-40/Ar-36 ratio of 334 + or - 102 is similar to the present-day atmospheric composition. This value is inconsistent with Sr and Nd isotopic signatures from Premier eclogite inclusions, which suggest a depleted mantle source. Preentrapment equilibration of the inclusions with an Ar-36-rich fluid is the most probable explanation for the low nonradiogenic composition.

  20. Multi-Kev X-Ray Emission from High-Z Gas Targets Fielded at Omega and NIF

    NASA Astrophysics Data System (ADS)

    May, Mark; Fournier, Kevin; Colvin, Jeff; Kane, Jave

    2010-11-01

    We report on the measured X-ray flux from gas-filled targets shot at both the OMEGA and NIF laser facilities. The OMEGA targets were 1.8 mm long, 1.95 mm in diameter Be cans filled with either a 50:50 Ar:Xe mixture, pure Ar, pure Kr or pure Xe at ˜ 1 atm. The OMEGA experiments heated the gas with 20 kJ of 3φ (˜350 nm) laser energy delivered in a 1 ns square pulse. The NIF targets were thin walled (25 μm), 4 mm long, 4 mm inner-diameter epoxy pipes filled with 1.2 atm of a 65:35 Ar:Xe mixture. The NIF experiments heated these targets with 350 kJ of 3φ (˜350 nm) laser energy delivered in a 5 ns square pulse at up to 75 TW of laser power. The emitted X-ray flux was monitored with the X-ray diode based DANTE instruments in the sub-keV range. Two-dimensional X-ray images (for energies 3-5 keV) of the targets were recorded with gated X-ray detectors. The X-ray spectra were recorded with the HENWAY crystal spectrometer at OMEGA. The results from both experiments will be compared. This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  1. GAS METERING PUMP

    DOEpatents

    George, C.M.

    1957-12-31

    A liquid piston gas pump is described, capable of pumping minute amounts of gas in accurately measurable quantities. The pump consists of a flanged cylindrical regulating chamber and a mercury filled bellows. Sealed to the ABSTRACTS regulating chamber is a value and having a gas inlet and outlet, the inlet being connected by a helical channel to the bellows. A gravity check valve is in the gas outlet, so the gas passes through the inlet and the helical channel to the bellows where the pumping action as well as the metering is accomplished by the actuation of the mercury filled bellows. The gas then flows through the check valve and outlet to any associated apparatus.

  2. arXiv.org and Physics Education

    NASA Astrophysics Data System (ADS)

    Ramlo, Susan

    2007-09-01

    The website arXiv.org (pronounced archive) is a free online resource for full-text articles in the fields of physics, mathematics, computer science, nonlinear science, and quantitative biology that has existed for about 15 years. Available directly at http://www.arXiv.org, this e-print archive is searchable. As of Jan. 3, 2007, arXiv had open access to 401,226 e-prints in the topic areas. Those who sign up for an ID and password can also sign up for daily submission abstract emails for specific subject classes of arXiv, including physics education, physics and society, and history of physics. Founded and developed by Paul Ginsparg when he was at Los Alamos National Laboratory, arXiv's original name was the LANL preprint archive or xxx.lanl.gov. The location and name changed after Ginsparg moved to the physics department at Cornell University. Today, arXiv is hosted and operated by Cornell University library. Mirror sites for arXiv exist worldwide.2

  3. 40Ar/ 39Ar analyses of clinopyroxene inclusions in African diamonds: implications for source ages of detrital diamonds

    NASA Astrophysics Data System (ADS)

    Phillips, D.; Harris, J. W.; Kiviets, G. B.

    2004-01-01

    Clinopyroxene inclusions in diamond contain elevated potassium contents and can potentially be dated by 40Ar/ 39Ar techniques. Previous 40Ar/ 39Ar studies of clinopyroxene inclusions contained in cleaved diamonds have suggested that argon, produced from the decay of potassium prior to eruption of the host kimberlite magma, diffuses to the diamond/clinopyroxene interface under mantle conditions. After intrusion and cooling below the closure temperature for argon diffusion, radiogenic argon is retained by the clinopyroxene inclusions. This behaviour complicates efforts to date diamond crystallisation events; however, extraction of inclusions from their host diamond should induce loss of all interface argon, thus raising the possibility of determining kimberlite emplacement ages. This possibility has important implications for constraining the source localities of detrital diamond deposits worldwide, with concomitant benefits to diamond exploration. To investigate this premise, 40Ar/ 39Ar laser probe results are presented for single clinopyroxene inclusions extracted from a total of fifteen gem-quality diamonds from the Mbuji-Mayi kimberlite in the Democratic Republic of Congo, and the Jwaneng and Orapa kimberlites in Botswana. Initial fusion analyses of clinopyroxene inclusions from Mbuji-Mayi diamonds yielded ages older than the time of host kimberlite intrusion, indicating partial retention of extraneous argon by the clinopyroxene inclusions themselves. Step-heating analyses of clinopyroxene inclusions from Orapa and Jwaneng diamonds produced older apparent ages from lower temperature steps and the 'rim' fragment of one Orapa inclusion. High temperature (fusion) analyses yielded younger apparent ages, commonly approaching the times of host kimberlite eruption. Total-gas integrated 40Ar/ 39Ar ages are mostly intermediate between the times of inferred diamond crystallisation and kimberlite eruption. Ca/K ratios for each sample are uniform across step

  4. Evaluation of sintering effects on SiC-incorporated UO2 kernels under Ar and Ar-4%H2 environments

    NASA Astrophysics Data System (ADS)

    Silva, Chinthaka M.; Lindemer, Terrence B.; Hunt, Rodney D.; Collins, Jack L.; Terrani, Kurt A.; Snead, Lance L.

    2013-11-01

    Silicon carbide (SiC) is suggested as an oxygen getter in UO2 kernels used for tristructural isotropic (TRISO) particle fuels and to prevent kernel migration during irradiation. Scanning electron microscopy and X-ray diffractometry analyses performed on sintered kernels verified that an internal gelation process can be used to incorporate SiC in UO2 fuel kernels. Even though the presence of UC in either argon (Ar) or Ar-4%H2 sintered samples suggested a lowering of the SiC up to 3.5-1.4 mol%, respectively, the presence of other silicon-related chemical phases indicates the preservation of silicon in the kernels during sintering process. UC formation was presumed to occur by two reactions. The first was by the reaction of SiC with its protective SiO2 oxide layer on SiC grains to produce volatile SiO and free carbon that subsequently reacted with UO2 to form UC. The second process was direct UO2 reaction with SiC grains to form SiO, CO, and UC. A slightly higher density and UC content were observed in the sample sintered in Ar-4%H2, but both atmospheres produced kernels with ˜95% of theoretical density. It is suggested that incorporating CO in the sintering gas could prevent UC formation and preserve the initial SiC content.

  5. Ab initio calculations of stationary points on the benzene-Ar and p-difluorobenzene-Ar potential energy surfaces: barriers to bound orbiting states.

    PubMed

    Moulds, Rebecca J; Buntine, Mark A; Lawrance, Warren D

    2004-09-08

    The potential energy surfaces of the van der Waals complexes benzene-Ar and p-difluorobenzene-Ar have been investigated at the second-order Møller-Plesset (MP2) level of theory with the aug-cc-pVDZ basis set. Calculations were performed with unconstrained geometry optimization for all stationary points. This study has been performed to elucidate the nature of a conflict between experimental results from dispersed fluorescence and velocity map imaging (VMI). The inconsistency is that spectra for levels of p-difluorobenzene-Ar and -Kr below the dissociation thresholds determined by VMI show bands where free p-difluorobenzene emits, suggesting that dissociation is occurring. We proposed that the bands observed in the dispersed fluorescence spectra are due to emission from states in which the rare gas atom orbits the aromatic chromophore; these states are populated by intramolecular vibrational redistribution from the initially excited level [S. M. Bellm, R. J. Moulds, and W. D. Lawrance, J. Chem. Phys. 115, 10709 (2001)]. To test this proposition, stationary points have been located on both the benzene-Ar and p-difluorobenzene-Ar potential energy surfaces (PESs) to determine the barriers to this orbiting motion. Comparison with previous single point CCSD(T) calculations of the benzene-Ar PES has been used to determine the amount by which the barriers are overestimated at the MP2 level. As there is little difference in the comparable regions of the benzene-Ar and p-difluorobenzene-Ar PESs, the overestimation is expected to be similar for p-difluorobenzene-Ar. Allowing for this overestimation gives the barrier to movement of the Ar atom around the pDFB ring via the valley between the H atoms as < or = 204 cm(-1) in S0 (including zero point energy). From the estimated change upon electronic excitation, the corresponding barrier in S1 is estimated to be < or = 225 cm(-1). This barrier is less than the 240 cm(-1) energy of 30(2), the vibrational level for which the

  6. The half-filled Landau level and topological insulator surfaces

    NASA Astrophysics Data System (ADS)

    Senthil, T.

    The metallic state of the half-filled Landau level - described originally in pioneering work by Halperin , Lee, and Read as a liquid of composite fermions - was proposed recently by Son to be described by a particle-hole symmetric effective field theory distinct from that in the prior literature. This talk will develop a simple picture of the particle-hole symmetric composite fermion through a modification of older pictures as electrically neutral ``dipolar'' particles. This picture, and the proposed particle-hole symmetric theory, will be further substantiated through a recently developed deep connection between the half-filled Landau level and correlated surface states of certain three dimensional topological insulators. The phenomenology of composite fermi liquids (with or without particle-hole symmetry) will be revisited. It will be shown that their heat/electrical transport dramatically violates the conventional Wiedemann-Franz law but satisfies a modified one. References: 1. Chong Wang and T. Senthil, ``Half-filled Landau Level, Topological Insulator Surfaces, and Three Dimensional Quantum Spin Liquids,'' cond-mat arXiv:1507.08290 (2015).

  7. Pulsed gas laser

    DOEpatents

    Anderson, Louis W.; Fitzsimmons, William A.

    1978-01-01

    A pulsed gas laser is constituted by Blumlein circuits wherein space metal plates function both as capacitors and transmission lines coupling high frequency oscillations to a gas filled laser tube. The tube itself is formed by spaced metal side walls which function as connections to the electrodes to provide for a high frequency, high voltage discharge in the tube to cause the gas to lase. Also shown is a spark gap switch having structural features permitting a long life.

  8. Xenocrysts and antecrysts and their effect on the precision of 40Ar/39Ar dates of explosive volcanic eruption

    NASA Astrophysics Data System (ADS)

    Smith, V.; Mark, D.; Blockley, S.; Weh, A.

    2010-12-01

    precise age on a relatively young eruption (~11 ka) we carried out >70 40Ar/39Ar dates of crystals. The sanidines were extracted from individual large pumices that were fragmented using selFrag so that the crystals remained intact. The crystals were then split into different size ranges prior to analysis on a high-sensitivity multicollector noble gas mass spectrometer (ARGUS). This approach allows us to assess how the incorporation of antecrysts and xenocrysts effect 40Ar/39Ar dates. Here we present the age ranges and discuss the results. *Research being carried out by members of the NERC funded Suigetsu 2006 Project led by Takeshi Nakagawa, Newcastle University, UK (http://www.suigetsu.org/)

  9. Particle-filled microporous materials

    DOEpatents

    McAllister, Jerome W.; Kinzer, Kevin E.; Mrozinski, James S.; Johnson, Eric J.

    1992-07-14

    A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated.

  10. Particle-filled microporous materials

    DOEpatents

    McAllister, Jerome W.; Kinzer, Kevin E.; Mrozinski, James S.; Johnson, Eric J.; Dyrud, James F.

    1990-01-01

    A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated.

  11. Particle-filled microporous materials

    DOEpatents

    McAllister, J.W.; Kinzer, K.E.; Mrozinski, J.S.; Johnson, E.J.; Dyrud, J.F.

    1990-09-18

    A microporous particulate-filled thermoplastic polymeric article is provided. The article can be in the form of a film, a fiber, or a tube. The article has a thermoplastic polymeric structure having a plurality of interconnected passageways to provide a network of communicating pores. The microporous structure contains discrete submicron or low micron-sized particulate filler, the particulate filler being substantially non-agglomerated. 3 figs.

  12. Safety in Royal Filling Factories

    DTIC Science & Technology

    1950-10-01

    factories and certain special trials were staged to ascertain effect of explosion on underground Magazines. (See C.S.A.R*s report, Glascoed trials). On...spacing were the result of long experience of the effects of explosions in filling, and incidentally resulted in a considerable economy in cost of...etc (9) Any ignition is quenched in its initial stages and/or an explosive effect kept to a minimum. (10) Operatives are made fully aware of the

  13. Atmospheric Ar and Ne returned from mantle depths to the Earth’s surface by forearc recycling

    PubMed Central

    Baldwin, Suzanne L.; Das, J. P.

    2015-01-01

    In subduction zones, sediments, hydrothermally altered lithosphere, fluids, and atmospheric gases are transported into the mantle, where ultrahigh-pressure (UHP) metamorphism takes place. However, the extent to which atmospheric noble gases are trapped in minerals crystallized during UHP metamorphism is unknown. We measured Ar and Ne trapped in phengite and omphacite from the youngest known UHP terrane on Earth to determine the composition of Ar and Ne returned from mantle depths to the surface by forearc recycling. An 40Ar/39Ar age [7.93 ± 0.10 My (1σ)] for phengite is interpreted as the timing of crystallization at mantle depths and indicates that 40Ar/39Ar phengite ages reliably record the timing of UHP metamorphism. Both phengite and omphacite yielded atmospheric 38Ar/36Ar and 20Ne/22Ne. Our study provides the first documentation, to our knowledge, of entrapment of atmospheric Ar and Ne in phengite and omphacite. Results indicate that a subduction barrier for atmospheric-derived noble gases does not exist at mantle depths associated with UHP metamorphism. We show that the crystallization age together with the isotopic composition of nonradiogenic noble gases trapped in minerals formed during subsolidus crystallization at mantle depths can be used to unambiguously assess forearc recycling of atmospheric noble gases. The flux of atmospheric noble gas entering the deep Earth through subduction and returning to the surface cannot be fully realized until the abundances of atmospheric noble gases trapped in exhumed UHP rocks are known. PMID:26542683

  14. Instrumentation development for planetary in situ 40Ar/39Ar geochronology

    NASA Astrophysics Data System (ADS)

    Davidheiser-Kroll, B.; Morgan, L. E.; Munk, M.; Warner, N. H.; Gupta, S.; Slaybaugh, R.; Harkness, P.; Mark, D. F.

    2015-12-01

    The chronology of the Solar System, particularly the timing of formation of extraterrestrial bodies and their features, is a major outstanding problem in planetary science. Although various chronological methods for in situ geochronology have been proposed (e.g. Rb-Sr, K-Ar), and even applied (K-Ar, Farley et al., 2014), the reliability, accuracy, and applicability of the 40Ar/39Ar method makes it by far the most desirable chronometer for dating extraterrestrial bodies. The method however relies on the neutron irradiation of samples, and thus a neutron source. We will discuss the challenges and feasibility of deploying a passive neutron source to planetary surfaces for the in situ application of the 40Ar/39Ar chronometer. Requirements in generating and shielding neutrons, as well as analyzing samples are discussed, along with an exploration of limitations such as mass, power, and cost. Two potential solutions for the in situ extraterrestrial deployment of the 40Ar/39Ar method will be presented. Although this represents a challenging task, developing the technology to apply the 40Ar/39Ar method on planetary surfaces would represent a major advance towards constraining the timescale of solar system formation and evolution.

  15. Ar-40/Ar-39 Studies of Martian Meteorite RBT 04262 and Terrestrial Standards

    NASA Technical Reports Server (NTRS)

    Park, J.; Herzog, G. F.; Turrin, B.; Lindsay, F. N.; Delaney, J. S.; Swisher, C. C., III; Nagao, K.; Nyquist, L. E.

    2014-01-01

    Park et al. recently presented an Ar-40/Ar-39 dating study of maskelynite separated from the Martian meteorite RBT 04262. Here we report an additional study of Ar-40/Ar-39 patterns for smaller samples, each consisting of only a few maskelynite grains. Considered as a material for Ar-40/Ar-39 dating, the shock-produced glass maskelynite has both an important strength (relatively high K concentration compared to other mineral phases) and some potentially problematic weaknesses. At Rutgers, we have been analyzing small grains consisting of a single phase to explore local effects that might be averaged and remain hidden in larger samples. Thus, to assess the homogeneity of the RBT maskelynite and for comparison with the results of, we analyzed six approx. 30 microgram samples of the same maskelynite separate they studied. Furthermore, because most Ar-40/Ar-39 are calculated relative to the age of a standard, we present new Ar-40/Ar-39 age data for six standards. Among the most widely used standards are sanidine from Fish Canyon (FCs) and various hornblendes (hb3gr, MMhb-1, NL- 25), which are taken as primary standards because their ages have been determined by independent, direct measurements of K and A-40.

  16. Theoretical and experimental investigation of Electron Transfer Mediated Decay in ArKr clusters

    NASA Astrophysics Data System (ADS)

    Fasshauer, Elke; Förstel, Marko; Mucke, Melanie; Arion, Tiberiu; Hergenhahn, Uwe

    2017-01-01

    We investigate the electronic decay of an Ar 3s-1 vacancy in medium sized ArKr clusters. The only energetically accessible, radiationless decay mechanism is Electron Transfer Mediated Decay Three (ETMD3). Here, the argon vacancy is filled by an electron from one krypton atom, and the excess energy is transferred to a second krypton atom which consequently emits an electron. For the theoretical calculation of ETMD3 spectra, in a bottom-up approach, we study the dependence of the decay width on the geometry of elementary sets of three atoms, from which any cluster can be composed. We simulate the ETMD3 spectra of medium sized ArKr clusters and compare the resulting spectra to experimental ETMD electron spectra presented earlier (Förstel et al, 2011) and in this work. We show that ETMD3 is the dominating relaxation mechanism for the cases studied here. Experimental secondary electron spectra from ArKr clusters are compared to pure Ar and pure Kr clusters.

  17. Filling high aspect ratio trenches by superconformal chemical vapor deposition: Predictive modeling and experiment

    NASA Astrophysics Data System (ADS)

    Wang, Wenjiao B.; Abelson, John R.

    2014-11-01

    Complete filling of a deep recessed structure with a second material is a challenge in many areas of nanotechnology fabrication. A newly discovered superconformal coating method, applicable in chemical vapor deposition systems that utilize a precursor in combination with a co-reactant, can solve this problem. However, filling is a dynamic process in which the trench progressively narrows and the aspect ratio (AR) increases. This reduces species diffusion within the trench and may drive the component partial pressures out of the regime for superconformal coating. We therefore derive two theoretical models that can predict the possibility for filling. First, we recast the diffusion-reaction equation for the case of a sidewall with variable taper angle. This affords a definition of effective AR, which is larger than the nominal AR due to the reduced species transport. We then derive the coating profile, both for superconformal and for conformal coating. The critical (most difficult) step in the filling process occurs when the sidewalls merge at the bottom of the trench to form the V shape. Experimentally, for the Mg(DMADB)2/H2O system and a starting AR = 9, this model predicts that complete filling will not be possible, whereas experimentally we do obtain complete filling. We then hypothesize that glancing-angle, long-range transport of species may be responsible for the better than predicted filling. To account for the variable range of species transport, we construct a ballistic transport model. This incorporates the incident flux from outside the structure, cosine law re-emission from surfaces, and line-of-sight transport between internal surfaces. We cast the transport probability between all positions within the trench into a matrix that represents the redistribution of flux after one cycle of collisions. Matrix manipulation then affords a computationally efficient means to determine the steady-state flux distribution and growth rate for a given taper angle. The

  18. Quantum-chemical modeling of boron and noble gas dopants in silicon

    NASA Technical Reports Server (NTRS)

    Aronowitz, S.

    1983-01-01

    The electron effects of the presence of boron and noble gas dopants in a model silicon lattice were investigated using a self-consistent charge extended Hueckel program. The extent of electronic interaction of the noble gas with the lattice is given by: Kr greater than Ar greater than Ne. Theoretically, boron diffusion in the presence of neon, argon or krypton was examined using a self-consistent charge extended Hueckel program. The net energy of interaction between boron and neon is strongly repulsive while argon-boron exhibits a region of relative stability; krypton exhibits behavior similar to argon though no region of stability was found for the range of separations used in the calculations. Finally, it is noted, from the relative energy of the topmost filled molecular orbital associated with boron (in an interstitial position), that activation of the boron does not require boron movement but can be accomplished by indirect transitions.

  19. Paleoclimate change in the Nakuru basin, Kenya, at 119 - 109 ka derived from δ18Odiatom and diatom assemblages and 40Ar/39Ar geochronology

    NASA Astrophysics Data System (ADS)

    Bergner, Andreas; Deino, Alan; Leng, Melanie; Gasse, Francoise

    2016-04-01

    A 4.5m-thick diatomite bed deposited during the cold interval of the penultimate interglacial at ~119 - 109 ka documents a period in which a deep freshwater lake filled the Nakuru basin in the Central Kenya Rift (CKR), East Africa. Palaeohydrological conditions of the basin are reconstructed for the paleolake highstand using δ18Odiatom and characterization of diatom assemblages. The age of the diatomite deposit is established by precise 40Ar/39Ar-dating of intercalated pumice tuffs. The paleolake experienced multiple hydrological fluctuations on sub-orbital (~1,500 to 2,000 years) time scales. The magnitude of the δ18Odiatom change (+/- 3‰) and significant changes in the plankton-littoral ratio of the diatom assemblage (+/- 25%) suggest that the paleolake record can be interpreted in the context of long-term climatic change in East Africa. Using 40Ar/39Ar age control and nominal diatomite-sedimentation rates we establish a simplified age model of paleohydrological vs. climatic change, from which we conclude that more humid conditions prevailed in equatorial East Africa during the late Pleistocene over a relatively long time interval of several thousands years. Then, extreme insolation at eccentricity maximum and weakened zonal air-pressure gradients in the tropics favored intensified ITCZ-like convection over East Africa and deep-freshwater lake conditions.

  20. INTERIOR VIEW WITH LADLE FILLING A PONT A MOUSSON PIPE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH LADLE FILLING A PONT A MOUSSON PIPE CASTING MACHINE (EITHER NO. 2 OR NO. 3) FOR PRODUCTION OF AN 8 INCH FASTTITE PIPE USED FOR GAS AND WATER TRANSMISSION. THIS FRENCH-MADE CASTING MACHINE MAKES 4, 6, 8, 10, AND 12 INCH PIPE. THE MACHINE CAN MAKE 48 EIGHT INCH PIPE AN HOUR AND UP TO 60 FOUR INCH PIPE PER HOUR. - American Cast Iron Pipe Company, Mixer Building, 1501 Thirty-first Avenue North, Birmingham, Jefferson County, AL

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    Xenon-filled proportional counters are used extensively in astronomy, particularly in the hard X-ray region. The choice of quench gas can have a significant effect on the operating characteristics of the instrument although the data necessary to make the choice are not easily obtainable. Results which detail the performance obtained from both cylindrical and parallel field geometries for a wide variety of readily available, ultrahigh or research grade purity, quench gases are presented.

  2. Abundance and Composition of K and Ca Bearing Minerals in Ordinary Chondrites and Their Application to Ar-Ar Dating

    NASA Astrophysics Data System (ADS)

    Weirich, J. R.; Swindle, T. D.

    2007-03-01

    Compositionally uniform albite accounts for all K in two H chondrites studied. Two K/Ca ratios are observed in individual meteorites in Ar-Ar experiments, however, which must indicate two separate releases of Ar from albite.

  3. Ar-Ar Thermochronlogy of Apollo 12 Impact-Melt Breccia 12033,638-1

    NASA Technical Reports Server (NTRS)

    Crow, C. A.; Cassata, W. S.; Jolliff, B. L.; Ziegler, R. A.; Borg, L. E.; Shearer, C. K.

    2017-01-01

    We have undertaken an Ar-Ar thermochronology investigation as part of a coordinated multichronometer analysis of a single Apollo 12 impact- melt breccia to demonstrate the wide range of information that can be obtained for a single complex rock. This has implications for the age of formation, component makeup, and subsequent impact/shock and exposure history of the sample. This study also serves as a capabilities demonstration for the proposed MoonRise Mission [1]. The goal of this investigation is to elucidate the history of this sample through coordinated 40Ar*/39Ar, Sm-Nd, Rb-Sr and zircon 207Pb-206Pb ages along with geochemical and petrographic context on a relatively small (approximately 450 mg) sample. Here, we report preliminary results of the Ar-Ar thermochronology.

  4. Ar-39-Ar-40 Ages of Euerites and the Thermal History of Asteroid 4-Vesta

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Garrison, Daniel H.

    2002-01-01

    Eucrite meteorites are igneous rocks that derive from a large asteroid, probably 4 Vesta. Prior studies have shown that after eucrites formed, most were subsequently metamorphosed to temperatures up to equal to or greater than 800 C, and much later many were brecciated and heated by large impacts into the parent body surface. The uncommon basaltic, unbrecciated eucrites also formed near the surface but presumably escaped later brecciation, whereas the cumulate eucrites formed at depth where metamorphism may have persisted for a considerable period. To further understand the complex HED parent body thermal history, we determined new Ar-39-Ar-40 ages for nine eucrites classified as basaltic but unbrecciated, six eucrites classified as cumulate, and several basaltic-brecciated eucrites. Relatively precise Ar-Ar ages of two cumulate eucrites (Moama and EET87520) and four unbrecciated eucrites give a tight cluster at 4.48 +/1 0.01 Gyr. Ar-Ar ages of six additional unbrecciated eucrites are consistent with this age, within their larger age uncertainties. In contrast, available literature data on Pb-Pb isochron ages of four cumulate eucrites and one unbrecciated eucrite vary over 4.4-4.515 Gyr, and Sm-147 - Nd-143 isochron ages of four cumulate and three unbrecciated eucrites vary over 4.41-4.55 Gyr. Similar Ar-Ar ages for cumulate and unbrecciated eucrites imply that cumulate eucrites do not have a younger formation age than basaltic eucrites, as previously proposed. Rather, we suggest that these cumulate and unbrecciated eucrites resided at depth where parent body temperatures were sufficiently high to cause the K-Ar and some other chronometers to remain open diffusion systems. From the strong clustering of Ar-Ar ages at approximately 4.48 Gyr, we propose that these meteorites were excavated from depth in a single large impact event approximately 4.48 Gyr ago, which quickly cooled the samples and started the K-Ar chronometer. A large (approximately 460 km) crater

  5. Experimental Constraints on He, Ne, Ar Behavior at Mantle Conditions

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Kelley, S. P.; Parman, S. W.; Cooper, R. F.

    2010-12-01

    We have experimentally constrained He, Ne and Ar mineral-melt partitioning for olivine, enstatite and spinel under mantle P-T conditions. The experiments were run in a piston cylinder apparatus. Run products were analyzed by UV laser ablation microprobe (UVLAMP). Our data (Ol, Opx, Sp), along with literature data (Cpx), suggest He, Ne and Ar are incompatible during mantle melting. Gem quality crystals of En100, Sp and Fo90 were polished using colloidal silica and loaded along with a MgO rich, synthetic MORB powder into a graphite inner and Pt outer capsule. Within the inner capsule, crystals were faced against graphite, an identical crystal or polished glassy carbon. Equal pressures (40-60 total bars) of He, Ne and Ar were loaded into the outer capsule before it was welded closed. The run conditions were 1450C and 1-2 GPa for 10 hrs (Brown University). Depth profiles of the mineral faces were obtained using a 193 nm excimer laser (Open University). The large crystal area and short wavelength laser allows for measurements with high depth resolution and concentration precision: a 400 um aperture with 150 nm ablation depth can provide a detection limit (3 sigma > blank) of ~500 ppb He, ~1 ppm Ne and ~500 ppb Ar. Three mineral ablation pits were imaged using a white light interferometer at Tufts University and indicate an ablation rate of ~25 nm/pulse. Glass ablation rates are estimated using previous measurements. The melts were generally understaturated with respect to He, Ne and Ar (1-10, 3-200 and 4-1000 PPM, respectively). Concentrations in the minerals were mostly below detection limits. Where detectable, near surface gas concentrations visually correlate with the amount of adhering graphite. This could be due to trapped/adsorbed gas in the graphite or to surface deformation produced by the graphite. The surface with the least adhering graphite and smoothest surface (faced against glassy carbon) shows no observable near surface enrichment of He, Ne or Ar. Given

  6. Ab initio transport coefficients of Ar+ ions in Ar for cold plasma jet modeling

    NASA Astrophysics Data System (ADS)

    Chicheportiche, A.; Lepetit, B.; Gadéa, F. X.; Benhenni, M.; Yousfi, M.; Kalus, R.

    2014-06-01

    Collision cross sections and transport coefficients are calculated for Ar+ ions, in the ground state 2P3/2 and in the metastable state 2P1/2, colliding with their parent gas. Differential and integral collision cross sections are obtained using a numerical integration of the nuclear Schrödinger equation for several published interaction potentials. The Cohen-Schneider semi-empirical model is used for the inclusion of the spin-orbit interaction. The corresponding differential collision cross sections are then used in an optimized Monte Carlo code to calculate the ion transport coefficients for each initial ion state over a wide range of reduced electric field. Ion swarm data results are then compared with available experimental data for different proportions of ions in each state. This allows us to identify the most reliable interaction potential which reproduces ion transport coefficients falling within the experimental error bars. Such ion transport data will be used in electrohydrodynamic and chemical kinetic models of the low temperature plasma jet to quantify and to tune the active species production for a better use in biomedical applications.

  7. The ArsD As(III) metallochaperone

    PubMed Central

    Ajees, A. Abdul; Yang, Jianbo

    2013-01-01

    Arsenic, a toxic metalloid widely existing in the environment, causes a variety of health problems. The ars operon encoded by Escherichia coli plasmid R773 has arsD and arsA genes, where ArsA is an ATPase that is the catalytic subunit of the ArsAB As(III) extrusion pump, and ArsD is an arsenic chaperone for ArsA. ArsD transfers As(III) to ArsA and increases the affinity of ArsA for As(III), allowing resistance to environmental concentrations of arsenic. Cys12, Cys13 and Cys18 in ArsD form a three sulfur-coordinated As(III) binding site that is essential for metallochaperone activity. ATP hydrolysis by ArsA is required for transfer of As(III) from ArsD to ArsA, suggesting that transfer occurs with a conformation of ArsA that transiently forms during the catalytic cycle. The 1.4 Å x-ray crystal structure of ArsD shows a core of four β-strands flanked by four α-helices in a thioredoxin fold. Docking of ArsD with ArsA was modeled in silico. Independently ArsD mutants exhibiting either weaker or stronger interaction with ArsA were selected. The locations of the mutations mapped on the surface of ArsD are consistent with the docking model. The results suggest that the interface with ArsA involves one surface of α1 helix and metalloid binding site of ArsD. PMID:21188475

  8. NEW ACCURATE MEASUREMENT OF {sup 36}ArH{sup +} AND {sup 38}ArH{sup +} RO-VIBRATIONAL TRANSITIONS BY HIGH RESOLUTION IR ABSORPTION SPECTROSCOPY

    SciTech Connect

    Cueto, M.; Herrero, V. J.; Tanarro, I.; Doménech, J. L.; Cernicharo, J.; Barlow, M. J.; Swinyard, B. M.

    2014-03-01

    The protonated argon ion, {sup 36}ArH{sup +}, was recently identified in the Crab Nebula from Herschel spectra. Given the atmospheric opacity at the frequency of its J = 1-0 and J = 2-1 rotational transitions (617.5 and 1234.6 GHz, respectively), and the current lack of appropriate space observatories after the recent end of the Herschel mission, future studies on this molecule will rely on mid-infrared observations. We report on accurate wavenumber measurements of {sup 36}ArH{sup +} and {sup 38}ArH{sup +} rotation-vibration transitions in the v = 1-0 band in the range 4.1-3.7 μm (2450-2715 cm{sup –1}). The wavenumbers of the R(0) transitions of the v = 1-0 band are 2612.50135 ± 0.00033 and 2610.70177 ± 0.00042 cm{sup –1} (±3σ) for {sup 36}ArH{sup +} and {sup 38}ArH{sup +}, respectively. The calculated opacity for a gas thermalized at a temperature of 100 K and with a linewidth of 1 km s{sup –1} of the R(0) line is 1.6 × 10{sup –15} × N({sup 36}ArH{sup +}). For column densities of {sup 36}ArH{sup +} larger than 1 × 10{sup 13} cm{sup –2}, significant absorption by the R(0) line can be expected against bright mid-IR sources.

  9. Dating samples of lunar soil from the Mare Crisium by the Ar/39/-Ar/40/ technique

    NASA Astrophysics Data System (ADS)

    Shanin, L. L.; Arakeliants, M. M.; Bogatikov, O. A.; Ivanenko, V. V.; Pupyrev, Iu. G.; Tarasov, L. S.; Frikh-Khar, D. I.

    1981-07-01

    Two samples (dolerite and gabbro fragments) from a depth of 184 cm in the Luna 24 core are dated using the Ar(39)-Ar(40) technique. The values obtained are found to be lower than all published isotopic ages for the Luna 24 samples. An analysis of possible dating errors of the lunar samples, together with the good agreement of the results from the Ar(39)-Ar(40) technique of geochronologic standards and anorthosite from the Korosten pluton with the results from Rb-Sr, U-Pb, and Sm-Nd methods, attests the reliability of the values.

  10. Rapid kimberlite ascent and the significance of Ar-Ar ages in xenolith phlogopites

    PubMed

    Kelley; Wartho

    2000-07-28

    Kimberlite eruptions bring exotic rock fragments and minerals, including diamonds, from deep within the mantle up to the surface. Such fragments are rapidly absorbed into the kimberlite magma so their appearance at the surface implies rapid transport from depth. High spatial resolution Ar-Ar age data on phlogopite grains in xenoliths from Malaita in the Solomon Islands, southwest Pacific, and Elovy Island in the Kola Peninsula, Russia, indicate transport times of hours to days depending upon the magma temperature. In addition, the data show that the phlogopite grains preserve Ar-Ar ages recorded at high temperature in the mantle, 700 degrees C above the conventional closure temperature.

  11. 39Ar - 40Ar Studies of Lherzolitic Shergottites Yamato 000097 and 984028

    NASA Technical Reports Server (NTRS)

    Park, J.; Nyquist, L. E.; Bogard, D. D.; Garrison, D. H.; Shih, C.-Y.; Mikouchi, T.; Misawa, K.

    2010-01-01

    Yamato 984028 (Y984028) was discovered by the Japanese Antarctic Research Expedition (JARE) in 1998 and recently classified as a lherzolitic shergottite with large pyroxene oikocrysts enclosing rounded olivine and chromites. It also contains shock veining and maskelynite. Y984028 is paired with the more recent lherzolitic shergottite finds Y000027/47/97 based on similarities in mineralogy and chemistry, as well as isotopic composition. We present here the studied Ar-39-Ar-40 of Y-984028 whole rock (WR) and pyroxene (Px), in order to gain better understanding of trapped Ar components with a comparison of the possibly-paired Y000097 Ar release.

  12. 40Ar/39Ar ages of the AD 79 eruption of Vesuvius, Italy

    USGS Publications Warehouse

    Lanphere, Marvin A.; Champion, Duane E.; Melluso, Leone; Morra, Vincenzo; Perrotta, Annamaria; Scarpati, Claudio; Tedesco, Dario; Calvert, Andrew T.

    2007-01-01

    The Italian volcano, Vesuvius, erupted explosively in AD 79. Sanidine from pumice collected at Casti Amanti in Pompeii and Villa Poppea in Oplontis yielded a weighted-mean 40Ar/39Ar age of 1925±66 years in 2004 (1σ uncertainty) from incremental-heating experiments of eight aliquants of sanidine. This is the calendar age of the eruption. Our results together with the work of Renne et al. (1997) and Renne and Min (1998) demonstrate the validity of the 40Ar/39Ar method to reconstruct the recent eruptive history of young, active volcanoes.

  13. 40Ar/39Ar ages of the AD 79 eruption of Vesuvius, Italy

    NASA Astrophysics Data System (ADS)

    Lanphere, Marvin; Champion, Duane; Melluso, Leone; Morra, Vincenzo; Perrotta, Annamaria; Scarpati, Claudio; Tedesco, Dario; Calvert, Andrew

    2007-01-01

    The Italian volcano, Vesuvius, erupted explosively in AD 79. Sanidine from pumice collected at Casti Amanti in Pompeii and Villa Poppea in Oplontis yielded a weighted-mean 40Ar/39Ar age of 1925±66 years in 2004 (1σ uncertainty) from incremental-heating experiments of eight aliquants of sanidine. This is the calendar age of the eruption. Our results together with the work of Renne et al. (1997) and Renne and Min (1998) demonstrate the validity of the 40Ar/39Ar method to reconstruct the recent eruptive history of young, active volcanoes.

  14. Ar-39-Ar-40 Evidence for Early Impact Events on the LL Parent Body

    NASA Technical Reports Server (NTRS)

    Dixon, E. T.; Bogard, D. D.; Garrison, D. H.; Rubin, A. E.

    2006-01-01

    We determined Ar-39-Ar-40 ages of eight LL chondrites, and one igneous inclusion from an LL chondrite, with the object of understanding the thermal history of the LL-chondrite parent body. The meteorites in this study have a range of petrographic types from LL3.3 to LL6, and shock stages from S1 to S4. These meteorites reveal a range of K-Ar ages from 23.66 to 24.50 Ga, and peak ages from 23.74 to 24.55 Ga. Significantly, three of the eight chondrites (LL4, 5, 6) have K-Ar ages of -4.27 Ga. One of these (MIL99301) preserves an Ar-39-Ar-40 age of 4.23 +/- 0.03 Ga from low-temperature extractions, and an older age of 4.52 +/- 0.08 Ga from the highest temperature extractions. In addition, an igneous-textured impact melt DOM85505,22 has a peak Ar-39-Ar-40 age of >= 4.27 Ga. We interpret these results as evidence for impact events that occurred at about 4.27 Ga on the LL parent body that produced local impact melts, reset the Ar-39-Ar-40 ages of some meteorites, and exhumed (or interred) others, resulting in a range of cooling ages. The somewhat younger peak age of 3.74 Ga from GR095658 (LL3.3) suggests an additional impact event close to timing of impact-reset ages of some other ordinary chondrites between 3.6-3.8 Ga. The results from MIL99301 suggest that some apparently unshocked (Sl) chondrites may have substantially reset Ar-39-Ar-40 ages. A previous petrographic investigation of MIL99301 suggested that reheating to temperatures less than or equal to type 4 petrographic conditions (600C) caused fractures in olivine to anneal, resulting in a low apparent shock stage of S1 (unshocked). The Ar-39-Ar-40 age spectrum of MIL99301 is consistent with this interpretation. Older ages from high-T extractions may date an earlier impact event at 4.52 +/- 0.08 Ga, whereas younger ages from lower-T extractions date a later impact event at 4.23 Ar-39-Ar-40 0.03 Ga that may have caused annealing of feldspar and olivine

  15. Ar^+ recombination with negative ions in a flowing afterglow: A new approach.

    NASA Astrophysics Data System (ADS)

    Miller, Thomas M.; Viggiano, A. A.

    2006-05-01

    Ion-ion recombination (mutual neutralization) has been previously studied in a flowing-afterglow Langmuir-probe apparatus, using the probe to measure the positive-ion and negative-ion densities as a function of distance (time) along the flow tube axis.^1 A different approach has been taken in the present work, applicable to Ar^+ (or Kr^+ and Xe^+) recombination reactions. A flowing electron-Ar^+ afterglow plasma is first established, and the ambipolar diffusion frequency is measured. Then, an electron attaching gas is added to the afterglow, and the electron attachment rate constant and product ion branching fractions are measured in the usual manner.^2 Finally, the reactant gas concentration is reduced enough that the attachment reaction has not gone to completion by the end of the flow tube. Modeling of the diffusion, attachment, and recombination processes allows us to determine rate constants for each negative ion type recombining with Ar^+. For example, Ar^+ neutralized by Cl^-, Cl2^-, and CCl2O^- produced in attachment to oxalyl chloride,^2 shows that Cl2^- recombines at about half the rate constant of CCl2O^-, and Cl^- + Ar^+ recombination is negligible. ^1D. Smith and N. G. Adams, in Physics of Ion-Ion and Electron-Ion Collisions, Ed. F. Brouillard and J. W. McGowan (Plenum, New York, 1983). ^2J. M. Van Doren, T. M. Miller, and A. A. Viggiano, J. Chem. Phys. (submitted).

  16. 40Ar/39Ar ages in deformed potassium feldspar: evidence of microstructural control on Ar isotope systematics

    NASA Astrophysics Data System (ADS)

    Reddy, Steven M.; Potts, Graham J.; Kelley, Simon P.

    2001-05-01

    Detailed field and microstructural studies have been combined with high spatial resolution ultraviolet laser 40Ar/39Ar dating of naturally deformed K-feldspar to investigate the direct relationship between deformation-related microstructure and Ar isotope systematics. The sample studied is a ~1,000 Ma Torridonian arkose from Skye, Scotland, that contains detrital feldspars previously metamorphosed at amphibolite-facies conditions ~1,700 Ma. The sample was subsequently deformed ~430 Ma ago during Caledonian orogenesis. The form and distribution of deformation-induced microstructures within three different feldspar clasts has been mapped using atomic number contrast and orientation contrast imaging, at a range of scales, to identify intragrain variations in composition and lattice orientation. These variations have been related to thin section and regional structural data to provide a well-constrained deformation history for the feldspar clasts. One hundred and forty-three in-situ 40Ar/39Ar analyses measured using ultraviolet laser ablation record a range of apparent ages (317-1030 Ma). The K-feldspar showing the least strain records the greatest range of apparent ages from 420-1,030 Ma, with the oldest apparent ages being found close to the centre of the feldspar away from fractures and the detrital grain boundary. The most deformed K-feldspar yields the youngest apparent ages (317-453 Ma) but there is no spatial relationship between apparent age and the detrital grain boundary. Within this feldspar, the oldest apparent ages are recorded from orientation domain boundaries and fracture surfaces where an excess or trapped 40Ar component resides. Orientation contrast images at a similar scale to the Ar analyses illustrate a significant deformation-related microstructural difference between the feldspars and we conclude that deformation plays a significant role in controlling Ar systematics of feldspars at both the inter- and intragrain scales even at relatively low

  17. High radon levels in subterranean environments: monitoring and technical criteria to ensure human safety (case of Castañar cave, Spain).

    PubMed

    Alvarez-Gallego, Miriam; Garcia-Anton, Elena; Fernandez-Cortes, Angel; Cuezva, Soledad; Sanchez-Moral, Sergio

    2015-07-01

    Castañar cave contains the highest radon gas ((222)Rn) concentration in Spain with an annual average of 31.9 kBq m(-)(3). Seasonal variations with summer minimums and maximum values in fall were recorded. The reduction of air-filled porosity of soil and rock by condensation or rainfalls hides the radon exchange by gas diffusion, determining this seasonal stair-step pattern of the radon activity concentration in underground air. The effective total dose and the maximum hours permitted have been evaluated for the guides and public safety with a highly detailed radon measurement along 2011 and 2012. A network of 12 passive detectors (kodalphas) has been installed, as well as, two radon continuous monitoring in the most interesting geological sites of the subterranean environment. A follow up of the recommended time (max. 50 min) inside the underground environment has been analysed since the reopen to public visitors for not surpassing the legal maximum effective dose for tourists and guides. Results shown that public visitors would receive in fall a 12.1% of the total effective dose permitted per visit, whereas in summer it is reduced to 8.6%, while the cave guide received a total effective dose of 6.41 mSv in four months. The spatial radon maps allow defining the most suitable touristic paths according to the radon concentration distribution and therefore, appropriate fall and summer touristic paths are recommended.

  18. Filling of carbon nanotubes and nanofibres

    PubMed Central

    Gately, Reece D

    2015-01-01

    Summary The reliable production of carbon nanotubes and nanofibres is a relatively new development, and due to their unique structure, there has been much interest in filling their hollow interiors. In this review, we provide an overview of the most common approaches for filling these carbon nanostructures. We highlight that filled carbon nanostructures are an emerging material for biomedical applications. PMID:25821693

  19. 7 CFR 58.923 - Filling containers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Filling containers. 58.923 Section 58.923 Agriculture... Procedures § 58.923 Filling containers. (a) The filling of small containers with product shall be done in a sanitary manner. The containers shall not contaminate or detract from the quality of the product in any...

  20. Identification of an AR Mutation-Negative Class of Androgen Insensitivity by Determining Endogenous AR Activity

    PubMed Central

    Ukat, M.; Schweikert, H. U.; Hiort, O.; Werner, R.; Drop, S. L. S.; Cools, M.; Hughes, I. A.; Audi, L.; Ahmed, S. F.; Demiri, J.; Rodens, P.; Worch, L.; Wehner, G.; Kulle, A. E.; Dunstheimer, D.; Müller-Roßberg, E.; Reinehr, T.; Hadidi, A. T.; Eckstein, A. K.; van der Horst, C.; Seif, C.; Siebert, R.; Ammerpohl, O.; Holterhus, P.-M.

    2016-01-01

    Context: Only approximately 85% of patients with a clinical diagnosis complete androgen insensitivity syndrome and less than 30% with partial androgen insensitivity syndrome can be explained by inactivating mutations in the androgen receptor (AR) gene. Objective: The objective of the study was to clarify this discrepancy by in vitro determination of AR transcriptional activity in individuals with disorders of sex development (DSD) and male controls. Design: Quantification of DHT-dependent transcriptional induction of the AR target gene apolipoprotein D (APOD) in cultured genital fibroblasts (GFs) (APOD assay) and next-generation sequencing of the complete coding and noncoding AR locus. Setting: The study was conducted at a university hospital endocrine research laboratory. Patients: GFs from 169 individuals were studied encompassing control males (n = 68), molecular defined DSD other than androgen insensitivity syndrome (AIS; n = 18), AR mutation-positive AIS (n = 37), and previously undiagnosed DSD including patients with a clinical suspicion of AIS (n = 46). Intervention(s): There were no interventions. Main Outcome Measure(s): DHT-dependent APOD expression in cultured GF and AR mutation status in 169 individuals was measured. Results: The APOD assay clearly separated control individuals (healthy males and molecular defined DSD patients other than AIS) from genetically proven AIS (cutoff < 2.3-fold APOD-induction; 100% sensitivity, 93.3% specificity, P < .0001). Of 46 DSD individuals with no AR mutation, 17 (37%) fell below the cutoff, indicating disrupted androgen signaling. Conclusions: AR mutation-positive AIS can be reliably identified by the APOD assay. Its combination with next-generation sequencing of the AR locus uncovered an AR mutation-negative, new class of androgen resistance, which we propose to name AIS type II. Our data support the existence of cellular components outside the AR affecting androgen signaling during sexual differentiation with high

  1. Resolving mantle and crustal contributions to ancient hydrothermal fluids: HeAr isotopes in fluid inclusions from Dae Hwa WMo mineralisation, South Korea

    NASA Astrophysics Data System (ADS)

    Stuart, F. M.; Burnard, P. G.; Taylor, R. P.; Turner, G.

    1995-11-01

    Helium and argon isotopes from fluid inclusions in individual colour zones (B, C, D, and E) of a large scheelite crystal from the 88 Ma Dae Hwa WMo deposit, South Korea, trace the source and history of the ore fluids. A gradual decrease of the fluid 3He/4He, 3He/36Ar, and 40Ar/36Ar from the core to the edge of the scheelite reflects the progressive dilution of a magmatic fluid by meteoric water and is consistent with the previously observed decrease of δ 18O H 2O and fluid inclusion homogenisation temperatures ( Th) (Shelton et al., 1987). The covariation of fluid inclusion HeAr isotope systematics with δ 18O and Th defines a magmatic component with 3He/4He = 1-2 × 10 -6, 3He/36Ar > 0.01 , and 40Ar/36Ar > 1000 . Anomalously high helium and argon isotope ratios in zone D fluids represents undiluted magmatic noble gases. This may reflect local variation in the magmatic gas flux or gas loss due to boiling of the hydrothermal fluids prior to mixing with magmatic gas. Helium and argon isotope systematics constrain mantle and crustal components in the hydrothermal fluids. 40Ar/3He (4.5 × 10 4) are close to the mid-ocean ridge basalt value, implying that 40Ar is mantle in origin. Radiogenic isotope ratios of the mantle endmember ( 40Ar/4He = 0.69 ± 0.06 ) are similar to contemporary geothermal fluids. The coincidence of mantle-derived He and Ar in the fluids is strong evidence that mantle melting during Late Cretaceous subduction triggered the crystal melting responsible for granite formation. 40Ar/4He of the meteoric fluid (0.007 ± 0.001) is far lower than the crystal production ratio (0.2) implying an origin in crust below 200°C.

  2. Laser propagation through full-scale, high-gain MagLIF gas pipes using the NIF

    NASA Astrophysics Data System (ADS)

    Pollock, Bradley; Sefkow, Adam; Goyon, Clement; Strozzi, David; Khan, Shahab; Rosen, Mordy; Campbell, Mike; Logan, Grant; Peterson, Kyle; Moody, John

    2016-10-01

    The first relevant measurements of laser propagation through surrogate high-gain MagLIF gas pipe targets at full scale have been performed at the NIF, using 30 kJ of laser drive from one quad in a 10 ns pulse at an intensity of 2e14 W/cm2. The unmagnetized pipe is filled with 1 atm of 99%/1% neopentane/Ar, and uses an entrance window of 0.75 um polyimide and an exit window of 0.3 um of Ta backed with 5 um of polyimide. Side-on x-ray emission from the plasma is imaged through the 100 um-thick epoxy wall onto a framing camera at four times during the drive, and is in excellent agreement with pre-shot HYDRA radiation-hydrodynamics modeling. X-ray emission from the Ta exit plane is imaged onto a streak camera to determine the timing and intensity of the laser burning through the pipe, and the Ar emission from the center of the pipe is spectrally- and temporally-resolved to determine the plasma electron temperature. Backscatter is measured throughout the laser drive, and is found to be of significance only when the laser reaches the Ta exit plane and produces SBS. These first results in unmagnetized surrogate gas fills are encouraging since they demonstrate sufficient laser energy absorption and low LPI losses within high-density long-scale-length plasmas for proposed high-gain MagLIF target designs. We will discuss plans to magnetize targets filled with high-density DT gas in future experiments. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.

  3. Dielectric waveguide gas-filled stark shift modulator

    DOEpatents

    Hutchinson, Donald P.; Richards, Roger K.

    2003-07-22

    An optical modulator includes a dielectric waveguide for receiving an optical beam and coupling energy of the optical beam into the waveguide. At least one Stark material is provided in the waveguide. A bias circuit generates a bias signal to produce an electrical field across the Stark material to shift at least one of the Stark absorption frequencies towards the frequency of the optical beam. A circuit for producing a time varying electric field across the Stark material modulates the optical beam. At least a portion of the bias field can be generated by an alternating bias signal, such as a square wave. A method of modulating optical signals includes the steps of providing a dielectric waveguide for receiving an optical beam and coupling energy of the optical beam into the waveguide, the waveguide having at least one Stark material disposed therein, and varying an electric field imposed across the Stark material.

  4. Towards understanding the differences in irradiation effects of He, Ne and Ar plasma by investigating the physical origin of their clustering in tungsten

    NASA Astrophysics Data System (ADS)

    Kong, Xiang-Shan; You, Yu-wei; Li, Xiang-yan; Wu, Xuebang; Liu, C. S.; Chen, Jun-Ling; Luo, G.-N.

    2016-10-01

    While inert gas seeding to improve energy confinement has been successfully applied in many tokamak experiments, questions remain as to the irradiation effects of inert gases on tungsten. In this paper, we have systematically investigated the clustering behaviors of the inert gas atoms He, Ne and Ar in plasma-facing tungsten using first-principles calculations. Small interstitial clusters, He m , Ne m , and Ar m , can form due to the attraction between the atoms and tend to expand along the (1 1 0) planes. The inert gas clusters induce strong lattice distortions and so it is energetically favorable for a self-interstitial atom to be emitted from the clusters when the numbers of atoms are above six, three, three for He m , Ne m , and Ar m respectively. The clustering behaviors can be well explained by the intrinsic repulsive interaction between the inert gas atoms and the attractive interaction coming from the reduced valence-electron density by interstitial inert gas atoms. Compared to He, the much greater attraction between the Ne/Ar atoms and the lower trigger condition of ‘self-trapping process’ for Ne/Ar clusters provide a reasonable explanation for the difference of irradiation effects on tungsten between He and Ne/Ar plasmas, i.e. Ne/Ar plasmas cannot result in the formation of holes/bubbles and fiber-form nanostructures on tungsten surface under the same irradiation conditions as He plasma.

  5. Effect of temperature on performance of {sup 3}He filled neutron proportional counters

    SciTech Connect

    Desai, Shraddha S.

    2014-04-24

    Neutron detectors used for cosmic neutron monitoring and various other applications are mounted in hostile environment. It is essential for detectors to sustain extreme climatic conditions, such as extreme temperature and humidity. Effort is made to evaluate the performance of detectors in extreme temperature in terms of pulse height distribution and avalanche formation. Neutron detectors filled with {sup 3}He incorporate an additive gas with quantity optimized for a particular application. Measurements are performed on neutron detectors filled with {sup 3}He and stopping gases Kr and CF{sub 4}. Detector performance for these fill gas combinations in terms of pulse height distribution is evaluated. Gas gain and Diethorn gas constants measured and analyzed for the microscopic effect on pulse formation. Results from these investigations are presented.

  6. ArsP: a methylarsenite efflux permease

    PubMed Central

    Chen, Jian; Madegowda, Mahendra; Bhattacharjee, Hiranmoy; Rosen, Barry P.

    2015-01-01

    Trivalent organoarsenic compounds are far more toxic than either pentavalent organoarsenicals or inorganic arsenite. Many microbes methylate inorganic arsenite (As(III)) to more toxic and carcinogenic methylarsenite (MAs(III)). Additionally, monosodium methylarsenate (MSMA or MAs(V)) has been used widely as an herbicide and is reduced by microbial communities to MAs(III). Roxarsone (3-nitro-4-hydroxybenzenearsonic acid) is a pentavalent aromatic arsenical that is used as antimicrobial growth promoter for poultry and swine, and its active form is the trivalent species Rox(III). A bacterial permease, ArsP, from Campylobacter jejuni, was recently shown to confer resistance to roxarsone. In this study C. jejuni arsP was expressed in Escherichia coli and shown to confer resistance to MAs(III) and Rox(III) but not to inorganic As(III) or pentavalent organoarsenicals. Cells of E. coli expressing arsP did not accumulate trivalent organoarsenicals. Everted membrane vesicles from those cells accumulated MAs(III)>Rox(III) with energy supplied by NADH oxidation, reflecting efflux from cells. The vesicles did not transport As(III), MAs(V) or pentavalent roxarsone. Mutation or modification of the two conserved cysteine residues resulted in loss of transport activity, suggesting that they play a role in ArsP function. Thus ArsP is the first identified efflux system specific for trivalent organoarsenicals. PMID:26234817

  7. Diffusive fractionation of noble gases in mantle with magma channels: Origin of low He/Ar in mantle-derived rocks

    NASA Astrophysics Data System (ADS)

    Yamamoto, Junji; Nishimura, Koshi; Sugimoto, Takeshi; Takemura, Keiji; Takahata, Naoto; Sano, Yuji

    2009-04-01

    By crushing olivine and pyroxene phenocrysts in volcanic rocks from Kyushu Island, Japan, we determined 3He/ 4He of 3-7 Ra and 40Ar/ 36Ar of up to 1750. These values are lower than those of MORB. 4He/ 40Ar* (down to 0.1) is much lower than the production ratio of 4He/ 40Ar* (1-5), where an asterisk denotes correction for the atmospheric contribution. Such values are typical of mantle-derived samples from the island arcs and active continental margins. Although the origin of the low 3He/ 4He and 40Ar/ 36Ar of subcontinental mantle has been widely discussed, low 4He/ 40Ar* has been given little attention. Actually, 3He/ 4He and 4He/ 40Ar* of phenocrysts overlap with those of subcontinental mantle xenoliths. Although noble gas compositions of phenocrysts are affected considerably by diffusive fractionation in ascending magma, they have little effect on the noble gases in the mantle xenoliths because it takes 100 years for He/Ar fractionation of ca. 15% for a mantle xenolith with 5 cm diameter. Therefore, the low 4He/ 40Ar* of the mantle xenoliths is inferred to result from another kinetic fractionation in the mantle. During generation and migration of magma in the mantle, lighter noble gases diffuse rapidly out into the magma. This diffusive fractionation can explain low 4He/ 40Ar* and somewhat low 3He/ 4He in the residual mantle. Furthermore, the combination of the diffusive fractionation and subsequent radiogenic ingrowth explain the fact that data from subcontinental mantle xenoliths have extremely low 3He/ 4He and various 4He/ 40Ar*. Consequently, 4He/ 40Ar* and 3He/ 4He in mantle-derived materials are proposed as indicators of the degree of noble gas depletion of the source mantle.

  8. Determination of Ar Concentration Evolution Within DIII-D Core Plasma by X-ray Ross Filter Method

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Edgell, D. H.; Brooks, N. H.; Snider, R. T.; West, W. P.; Wade, M. R.

    2001-10-01

    Injection of the non-recycling noble gas Ar into the DIII-D divertor is a promising technique for reducing the heat load on the plates; it also seems to improve thermal transport in an advanced operating mode. During such experiments core plasma contamination by migrating Ar can be investigated by measuring the evolution of the Ar concentration profile using the Ross filter method implemented on the fan shaped X-ray poloidal diagnostics on DIII-D. A Ross filter with energy pass band centered on the ArXVII K_α line at 3.14 keV, discriminating Ar K_α line against background radiation, was used on DIII-D. A high sensitivity to the injected quantity of Ar and good discrimination against Ne was observed. We present reconstruction of Ar concentration profiles from the chord-integrated measurements using the measured Te and ne profiles. Using the transport code MIST, the impurity diffusion coefficients can be determined by matching the time evolution of the Ar concentration evolution.

  9. Correlation diagrams in 40 Ar/39Ar dating: is there a correct choice?

    USGS Publications Warehouse

    Dalrymple, G.B.; Lanphere, M.A.; Pringle, M.S.

    1988-01-01

    Contrary to published assertions, the 2 types of correlation diagrams used in the interpretation of 40Ar/39Ar incremental-heating data yield the same information provided the correct mathematics are used for estimating correlation coefficients and for the least squares fit. The choice is simply between 2 illustrative, graphical displays, neither of which is fundamentally superior to the other. -Authors

  10. [sup 40]Ar/[sup 39]Ar mineral ages from southwestern Penobscot Bay, Maine: Evidence for Silurian metamorphism

    SciTech Connect

    West, D.P. Jr.; Guidotti, C.V.; Lux, D.R. . Dept. of Geological Sciences)

    1992-01-01

    The nature and timing of metamorphic events in the Coastal Lithotectonic Block of Maine remain poorly understood. Immediately west and southwest of Penobscot Bay the rocks are polymetamorphic showing evidence for at least two episodes of amphibolite facies metamorphism and later, perhaps regionally extensive, retrograde events. Hornblende mineral separates from two amphibolites din the Port Clyde area have identical Ar-40/Ar-39 plateau ages of 414.0 [+-] 3.3 and 414.0 [+-] 3.9 Ma. These ages are interpreted to reflect the time of cooling following the last significant thermal event in this area. Biotite from an amphibolite in the Port Clyde area gives a total gas age of 346.5 [+-] 3.2 Ma. Hornblende from an amphibolite 7 km to the west near Friendship gives a nearly concordant release spectrum with a plateau age of 369.0 [+-] 3.7 Ma. Coexisting biotite from this amphibolite gives a total gas age of 289.2 [+-] 2.7 Ma. Muscovite from the Waldoboro pluton has a nearly concordant release spectrum with a plateau age of 306.3 [+-] 2.2 Ma. Biotite from this sample gives a total gas age of 288.9 [+-] 2.2 Ma. The 414.0 Ma hornblende cooling ages from the Port Clyde area reflect cooling following a significant high grade Silurian thermal event. This Silurian metamorphism is the same age as tectonothermal events in the Nashoba Terrane in eastern Massachusetts, the Kingston Complex in southern New Brunswick, the Aspy Terrane in Cape Breton island, Nova Scotia, and the Hermitage Flexure in southern Newfoundland.d Thus a distinctive Silurian tectonothermal province located along the western edge of the Avalon Zone appears to extend discontinuously from Massachusetts to Newfoundland.

  11. AR-40 AR-39 Age of an Impact-Melt Lithology in DHOFAR 961

    NASA Technical Reports Server (NTRS)

    Frasl, B.; Cohen, B. A.; Li, Z.-H.; Jolliff, B.; Korotev, R.; Zeigler, R.

    2016-01-01

    The South Pole-Aitken (SPA) basin is the stratigraphically oldest identifiable lunar basin and is therefore one of the most important targets for absolute age-dating to help understand whether ancient lunar bombardment history smoothly declined or was punctuated by a cataclysm. The SPA basin also has another convenient property, a geochemically distinct interior, unobscured by extensive mare basalt fill. A case has been made for the possible origin of the Dhofar 961 lunar meteorite in the South Pole-Aitken (SPA) basin, based on comparing its composition with Lunar Prospector gamma-ray data for the interior of the SPA basin. Dhofar 961 contains several different impact-melt (IM) lithologies. Jolliff et al. described two classes of mafic impact-melt lithologies, one dominated by olivine (Lithology A) and the other by plagioclase (An 95-96.5) (Lithology B). Broad-beam analyses of these lithologies yielded (is) approximately 14.0 wt% FeO, 11.7 wt% MgO, and 15.4 wt% Al2O3. Lithologies A and B differ by approximately 2.5% Al2O3, 1.5% FeO and 1.5% MgO, consistent with the occurrence of olivine phenocrysts in A and plagioclase clasts in B. Both lithologies are considerably more mafic than the Apollo mafic impact-melt breccias, corresponding to olivine gabbronorite. Joy et al. used U-Pb dating to investigate phosphate fragments in the Dhofar 961 matrix and impact-melt clasts. Matrix phosphates have 4.34 to 4 Ga ages, consistent with ancient KREEP-driven magmatic episodes and Pre-Nectarian ((is) greater than 3.92 Ga). Phosphates found within Dhofar 961 crystalline impact melt breccia clasts range from 4.26 to 3.89 Ga, potentially recording events throughout the basin forming epoch of lunar history. The youngest reset ages in the Dhofar 961 sample represent an upper limit for the time of formation of the meteorite. Joy et al suggested this age represents the final impact that mixed and consolidated several generations of precursor rocks into the Dhofar meteorite group

  12. Experimental Constraints on He, Ne, and Ar Solubility in Serpentinite

    NASA Astrophysics Data System (ADS)

    Krantz, J. A.; Parman, S. W.; Kelley, S. P.; Smye, A.; Jackson, C.; Cooper, R. F.

    2015-12-01

    Experiments have been performed to constrain the solubility of He, Ne, and Ar in natural samples of antigorite from three locations. Geochemical analyses of exhumed subduction zone material [1] and well gases [2] indicate that noble gases are recycled from the surface of the earth into the mantle. The mechanism by which uncharged atoms can be bound to a mineral and subsequently recycled remains unclear, but recent experimental work suggests that ring structures in silicate minerals are ideal sites for noble gases [3]. Serpentine contains such ring structures and is abundant in subducting slabs, providing significant potential for control of the recycling of noble gases. Experiments were performed in a cold seal pressure vessel at 350°C using a mix of equal parts He, Ne, and Ar as the pressure media (Brown University, USA). Pressures varied from 0.15 to 1.13 kbar total pressure and durations varied from 20 to 188 hours. Samples were analyzed by UV laser ablation, noble gas mass spectrometry (Open University, UK). He and Ne reached equilibrium during the experiments and both exhibit Henrian behavior. Data from the cleanest sample reduces the error by approximately an order of magnitude over previous work [3] and confirms that He is significantly more soluble (HCHe=6.05x10-10 mol/g/bar) than Ne (HCNe=5.12x10-12 mol/g/bar) in antigorite. Preliminary data from the cleanest sample suggests that Ar is more soluble than both He and Ne (HCAr=1.94x10-10 mol/g/bar). This provides a mechanism for fractionation of noble gases during recycling. 1. Kendrick, M.A., Scambelluri, M., Honda, M., Phillips, D., Nature Geoscience, 4, 807-812, 2011 2. Holland, G., and Ballentine, C.J., Nature, 441, 186-191, 2006 3. Jackson, C.R.M., Parman, S.W., Kelley, S.P., Cooper, R.F., GCA, 159, 1-15, 2015

  13. Inert gas thrusters

    NASA Technical Reports Server (NTRS)

    Kaufman, H. R.; Robinson, R. S.

    1980-01-01

    Some advances in component technology for inert gas thrusters are described. The maximum electron emission of a hollow cathode with Ar was increased 60-70% by the use of an enclosed keeper configuration. Operation with Ar, but without emissive oxide, was also obtained. A 30 cm thruster operated with Ar at moderate discharge voltages give double-ion measurements consistent with a double ion correlation developed previously using 15 cm thruster data. An attempt was made to reduce discharge losses by biasing anodes positive of the discharge plasma. The reason this attempt was unsuccessful is not yet clear. The performance of a single-grid ion-optics configuration was evaluated. The ion impingement on the single grid accelerator was found to approach the value expected from the projected blockage when the sheath thickness next to the accelerator was 2-3 times the aperture diameter.

  14. Defect-enhanced void filling and novel filled phases of open-structure skutterudites

    DOE PAGES

    Xi, Lili; Qiu, Yuting; Shi, Xun; ...

    2015-05-14

    Here, we report the design of novel filled CoSb3 skutterudite phases based on a combination of filling and Sb-substituted Ga/In defects. Ga/In doped skutterudite phases with Li-, Nd-, and Sm-fillings can be formed via this strategy, which can have relatively wider ranges of carrier concentration than other conventional filled skutterudite phases.

  15. 30 CFR 816.72 - Disposal of excess spoil: Valley fills/head-of-hollow fills.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... incorporated into the design and construction of the fill as follows. (1) The fill shall have, along the... spoil fill and from seeps and springs in the foundation of the disposal area. Rocks used in the rock... maintained at the head of the fill during and after construction, to intercept surface runoff and...

  16. Defect-enhanced void filling and novel filled phases of open-structure skutterudites

    SciTech Connect

    Xi, Lili; Qiu, Yuting; Shi, Xun; Zhang, Wenqing; Chen, Lidong; Singh, David J.; Yang, Jihui

    2015-05-14

    Here, we report the design of novel filled CoSb3 skutterudite phases based on a combination of filling and Sb-substituted Ga/In defects. Ga/In doped skutterudite phases with Li-, Nd-, and Sm-fillings can be formed via this strategy, which can have relatively wider ranges of carrier concentration than other conventional filled skutterudite phases.

  17. Hazard evaluation for 244-AR vault facility

    SciTech Connect

    BRAUN, D.J.

    1999-08-25

    This document presents the results of a hazard identification and evaluation performed on the 244-AR Vault Facility to close a USQ (USQ No.TF-98-0785, Potential Inadequacy in Authorization Basis (PIAB): To Evaluate Miscellaneous Facilities Listed In HNF-2503 And Not Addressed In The TWRS Authorization Basis) that was generated as part of an evaluation of inactive TWRS facilities. A hazard evaluation for the Hanford Site 244-AR Vault Facility was performed. The process and results of the hazard evaluation are provided in this document. A previous hazard evaluation was performed for the 244-AR Vault Facility in 1996 in support of the Basis for Interim Operation (BIO) (HNF-SD-WM-BIO-001, 1998, Revision 1) of the Tank Waste Remediation System (TWRS). The results of that evaluation are provided in the BIO. Upon review of those results it was determined that hazardous conditions that could lead to the release of radiological and toxicological material from the 244-AR vaults due to flooding was not addressed in the original hazards evaluation. This supplemental hazard evaluation addresses this oversight of the original hazard evaluation. The results of the hazard evaluation were compared to the current TWRS BIO to identify any hazardous conditions where Authorization Basis (AB) controls may not be sufficient or may not exist. This document is not part of the AB and is not a vehicle for requesting changes to the AB. It is only intended to provide information about hazardous conditions associated with the condition and configuration of the 244-AR vault facility. The AB Control Decision process could be used to determine the applicability and adequacy of existing AB controls as well as any new controls that may be needed for the identified hazardous conditions associated with 244-AR vault flooding. This hazard evaluation does not constitute an accident analysis.

  18. Gas-Recovery System

    DOEpatents

    Heckman, R. A.

    1971-12-14

    Nuclear explosions have been proposed as a means for recovering gas from underground gas-bearing rock formations. In present practice, the nuclear device is positioned at the end of a long pipe which is subsequently filled with grout or concrete. After the device is exploded, the grout is drilled through to provide a flow path for the released gas to the ground surface. As settled grout is brittle, often the compressive shock of the explosion fractures the grout and deforms the pipe so that it may not be removed nor reused. In addition, the pipe is sometimes pinched off completely and the gas flow is totally obstructed. (2 claims)

  19. Gas-recovery system

    DOEpatents

    Heckman, R.A.

    1971-12-14

    Nuclear explosions have been proposed as a means for recovering gas from underground gas-bearing rock formations. In present practice, the nuclear device is positioned at the end of a long pipe which is subsequently filled with grout or concrete. After the device is exploded, the grout is drilled through to provide a flow path for the released gas to the ground surface. As settled grout is brittle, often the compressive shock of the explosion fractures the grout and deforms the pipe so that it may not be removed nor reused. In addition, the pipe is sometimes pinched off completely and the gas flow is totally obstructed. (2 claims)

  20. Optical and electrical characterization of an atmospheric pressure microplasma jet for Ar/CH{sub 4} and Ar/C{sub 2}H{sub 2} mixtures

    SciTech Connect

    Yanguas-Gil, A.; Focke, K.; Benedikt, J.; Keudell, A. von

    2007-05-15

    A rf microplasma jet working at atmospheric pressure has been characterized for Ar, He, and Ar/CH{sub 4} and Ar/C{sub 2}H{sub 2} mixtures. The microdischarge has a coaxial configuration, with a gap between the inner and outer electrodes of 250 {mu}m. The main flow runs through the gap of the coaxial structure, while the reactive gases are inserted through a capillary as inner electrode. The discharge is excited using a rf of 13.56 MHz, and rms voltages around 200-250 V and rms currents of 0.4-0.6 A are obtained. Electron densities around 8x10{sup 20} m{sup -3} and gas temperatures lower than 400 K have been measured using optical emission spectroscopy for main flows of 3 slm and inner capillary flows of 160 SCCM. By adjusting the flows, the flow pattern prevents the mixing of the reactive species with the ambient air in the discharge region, so that no traces of air are found even when the microplasma is operated in an open atmosphere. This is shown in Ar/CH{sub 4} and Ar/C{sub 2}H{sub 2} plasmas, where no CO and CN species are present and the optical emission spectroscopy spectra are mainly dominated by CH and C{sub 2} bands. The ratio of these two species follows different trends with the amount of precursor for Ar/CH{sub 4} and Ar/C{sub 2}H{sub 2} mixtures, showing the presence of distinct chemistries in each of them. In Ar/C{sub 2}H{sub 2} plasmas, CH{sub x} species are produced mainly by electron impact dissociation of C{sub 2}H{sub 2} molecules, and the CH{sub x}/C{sub 2}H{sub x} ratio is independent of the precursor amount. In Ar/CH{sub 4} mixtures, C{sub 2}H{sub x} species are formed mainly by recombination of CH{sub x} species through three-body reactions, so that the CH{sub x}/C{sub 2}H{sub x} ratio depends on the amount of CH{sub 4} present in the mixture. All these properties make our microplasma design of great interest for applications such as thin film growth or surface treatment.

  1. 76 FR 27077 - Agency Information Collection Activities: Form AR-11 and Form AR-11SR, Extension of an Existing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-10

    ... SECURITY U.S. Citizenship and Immigration Services Agency Information Collection Activities: Form AR-11 and Form AR- 11SR, Extension of an Existing Information Collection; Comment Request ACTION: 60-Day Notice of Information Collection under Review: Form AR- 11 and Form AR-11SR, Alien's Change of Address...

  2. Ar-Ar and I-Xe Ages and the Thermal History of IAB Meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Garrison, Daniel H.; Takeda, Hiroshi

    2005-01-01

    Studies of several samples of the large Caddo County IAB iron meteorite reveal andesitic material, enriched in Si, Na, Al and Ca, which is essentially unique among meteorites. This material is believed to have formed from a chondritic source by partial melting and to have further segregated by grain coarsening. Such an origin implies extended metamorphism of the IAB parent body. New Ar-39- Ar-40 ages for silicate from three different Caddo samples are consistent with a common age of 4.50-4.51 Gyr ago. Less well defined Ar-Ar degassing ages for inclusions from two other IABs, EET8333 and Udei Station, are approx.4.32 Gyr, whereas the age for Campo del Cielo varies considerably over approx.3.23-4.56 Gyr. New I-129-Xe-129 ages for Caddo County and EET8333 are 4557.9+/-0.1 Myr and 4557-4560 Myr, respectively, relative to an age of 4562.3 Myr for Shallowater. Considering all reported Ar-Ar degassing ages for IABs and related winonaites, the range is approx.4.32-4.53 Gyr, but several IABs give similar Ar ages of 4.50-4.52 Gyr. We interpret these older Ar ages to represent cooling after the time of last significant metamorphism on the parent body, and the younger ages to represent later 40Ar diffusion loss. The older Ar-Ar ages for IABs are similar to Sm-Nd and Rb-Sr isochron ages reported in the literature for Caddo County. Considering the possibility that IAB parent body formation was followed by impact disruption, reassembly, and metamorphism (e.g., Benedix et al. 2000), the Ar-Ar ages and IAB cooling rates deduced from Ni concentration profiles in IAB metal (Herpfer et al., 1994) are consistent if the time of the post-assembly metamorphism was as late as approx.4.53 Gyr ago. However, I-Xe ages reported for some IABs define much older ages of approx.4558-4566 Myr, which cannot easily be reconciled with the much younger Ar-Ar and Sm-Nd ages. An explanation for the difference in radiometric ages of IABs may reside in combinations of the following: a) I-Xe ages have very

  3. 40Ar/39Ar and K/Ar dating of low grade metamorphism: examples on metabasites from Central Chile

    NASA Astrophysics Data System (ADS)

    Aguirre, L.; Feraud, G.; Fuentes, F.; Delbar, M.; Morata, D.

    2003-04-01

    Dating low to very low-grade burial metamorphic assemblages is often difficult because of (1) few mineral phases compositionally suitable to apply the 40Ar/39Ar and K-Ar methods, and (2) small amount in which these phases are commonly found. K-feldspar adularia, sericitic mica, and celadonite are the best known K-bearing secondary minerals. We present some successful attempts to analyse two distinct secondary phases from a same volcanic formation that allow to test the validity of the measured ages. These ages have been also compared with the crystallisation age of the volcanic rocks in which the secondary phases were lately developed. Adularia and sericite were selected from basic lava flows from a 3 to 13 km thick Cretaceous sequence from the Coastal Range of central Chile, at two different locations: the Bustamante Hill (west from Santiago), and the Cordón de Chacana, c. 80 km further north. Adularia came from a low-variance assemblage with pumpellyite, chlorite and low-albite contained in amygdules whereas sericite was present in milky-white strongly sericitized plagioclase crystals. While small clusters of rare fresh plagioclase grains from lava flows from Bustamante and Chacana displayed concordant plateau ages 119.4 ± 2.4 (2 sigma) and 118.7 ± 0.6 Ma, respectively, the adularia from the same formations gave sensibly younger ages around 94 Ma (high temperature steps), and 96.8 ± 0.2 Ma (plateau age) in Bustamante and Chacana, respectively. Sericite ages were measured in situ into single crystals of strongly transformed plagioclases. The relative proportion of sericite and plagioclase corresponding to each degasing step was monitored by measuring the Ca/K ratio (deduced from 37ArCa/39Ar_K). While intermediate ages were measured on some sericite of both sites (corresponding to a variable but permanent contribution of plagioclase on each step), a plateau age of 97.0 ± 1.6 Ma (concordant with adularia) could be obtained on a strongly sericitized plagioclase

  4. The use of engineered lightweight fill for landfill cover remediation

    SciTech Connect

    Poe, D.E.; Gardner, R.B.; Xiaoyu Fu

    1995-12-31

    In 1991, SCS was retained to provide design and construction engineering services to retrofit a landfill gas migration control system and regrade/repair an existing low-permeability soil final cover system for a 10-acre closed landfill located in west-central Florida. The final cover system modifications consisted of regrading the top of the landfill to re-establish positive drainage across and off of the top of the landfill. While active, the landfill had received municipal solid waste (MSW), commercial solid waste, and various industrial wastes and sludges. The landfill was closed in the early 1980`s. At the time of filling, the subject landfill was operated as a trench fill. A series of 40-foot deep trenches were excavated across the fill area, and the MSW was placed and compacted into the trenches. The soil excavated during construction of the trenches was used to construct berms along the sides of the individual trenches. No constructed bottom liner or leachate collection system was incorporated into the design. This report presents the results of a conceptual evaluation of utilizing expanded polystyrene blocks or Geofoam, as the lightweight fill component for an alternative cover remediation.

  5. Integrated routing and fill for self-aligned double patterning (SADP) using grid-based design

    NASA Astrophysics Data System (ADS)

    Song, Youngsoo; Lee, Jeemyung; Lee, Seongmin; Shin, Youngsoo

    2016-03-01

    Self-aligned double patterning (SADP) has been proposed as an alternative patterning solution for sub-10nm technology because of delay of advanced lithography beyond 193nm ArF. In conventional SADP, line and space style of dummy metal fills are inserted once main design is complete. A large buffer distance is required around the main design because no further verification of main design (in presence of fills) is performed. This causes irregular pattern density, which becomes a source of process variations. We propose integrated-fill, in which main design and dummy fill insertion are performed together. This requires a change in overall design flow, which we discuss. Integrated-fill is demonstrated in M2 layer of SADP process; M2 density increases by 15.7% with 2.3% reduction in standard deviation of density distribution; metal thickness variation is also reduced by 24%. More dummy fills cause increased coupling capacitance, which however is shown to be insignificant.

  6. On the 40Ar/39Ar Dating of Low-Potassium Ocean Crust Basalt from IODP Expedition 349, South China Sea

    NASA Astrophysics Data System (ADS)

    Koppers, A. A. P.

    2014-12-01

    Accurate age dates for the basement rocks in the South China Sea (SCS) basins were lacking before the execution of International Ocean Discovery Program (IODP) Expedition 349 in early 2014. This left a large margin of error in estimated opening ages for the SCS and rendered various hypotheses regarding its opening mechanism and history untested, hampering our understanding of East Asian tectonic and paleoenvironmental evolution. Therefore, high-precision 40Ar/39Ar age dating lies at the heart of Expedition 349, which in particular aimed to determine the timing of the start and cessation of seafloor spreading in the SCS. In addition, the recovery of a complete seamount apron section at Site U1431 allows 40Ar/39Ar dating of abundantly present plagioclase and biotite crystals to help establish a detailed chronology of the sedimentary and volcaniclastic sequences cored. Here we present the first 40Ar/39Ar incremental heating ages on the low-potassium (~0.1-0.2 wt% K2O) and the least altered (loss on ignition < 1.5%) mid-ocean ridge basalt (MORB) from the SCS. Plagioclase and groundmass samples were prepared using conventional mineral separation techniques, acid-leaching and hand-picking. Analyses were carried out using a new ARGUS-VI multi-collector noble gas mass spectrometer. Ages are expected to have precisions ranging between 0.1-0.3 Ma (2σ), which will allow us to precisely and accurately date the final emplacement of basalts at Sites U1431, U1433 and U1434 in the SCS basin, just prior to the cessation of spreading as all sites were slightly offset from the relict spreading center.

  7. PVD Cu trench-fill by viscous flow at high temperatures

    NASA Astrophysics Data System (ADS)

    Wu, Zhiyuan

    The scaling of integrated circuits has led to new challenges in Cu interconnect fabrication. It is getting difficult to fill narrow trenches, e.g. 20 nm wide, by Cu electroplating. In this work, a high temperature PVD Cu viscous flow trench fill process was explored to overcome the difficulties of filling narrow and high aspect ratio trenches. We have tested and found TaN and MoN to be good barriers, and Ru a good wetting surface for Cu. The three metals, Ta, Mo and Ru, are thus suitable for use as a thin liner to provide adhesion between the filled Cu and the dielectrics. We have therefore studied and compared Cu viscous flow trench filling on Ru, Mo and Ta liners. Cross-sectional TEM was employed to examine the trench fill profiles under different viscous flow conditions. We have found that a continuous Cu seed deposited at room temperature was essential to allow successful Cu viscous flow. The liner material's effect on Cu seed agglomeration was thus critical. It was shown that viscous flow on a Ru liner with a continuous Cu seed can fill narrow trenches (300 nm wide) at a high aspect ratio (a/r = 5), and produce maximized Cu grain size without post-fill annealing. A thicker Cu seed is required on the Mo liner for a successful viscous fill. However, on a Ta liner, because of poor Cu wetting, it is difficult to maintain a continuous Cu seed coverage at high temperatures, and the viscous fill was unsuccessful. To fill ultra-narrow (≤ 48 nm wide) and high aspect ratio (a/r ≥ 4) trenches, a lower deposition rate was needed. Agglomeration of the whole Cu fill at high temperatures is a key issue, which still remains to be overcome. Computer simulations of the viscous flow trench fill process were carried out, taking into account the effects of incoming flux divergence and Cu seed coverage. Our simulations indicated that a successful viscous trench fill relies on a continuous Cu seed coverage and a high surface mobility. Viscous flow is not sensitive to the

  8. 40Ar/39Ar dating of the eruptive history of Mount Erebus, Antarctica: summit flows, tephra, and caldera collapse

    NASA Astrophysics Data System (ADS)

    Harpel, Christopher J.; Kyle, Philip R.; Esser, Richard P.; McIntosh, William C.; Caldwell, David A.

    2004-12-01

    Eruptive activity has occurred in the summit region of Mount Erebus over the last 95 ky, and has included numerous lava flows and small explosive eruptions, at least one plinian eruption, and at least one and probably two caldera-forming events. Furnace and laser step-heating 40Ar/39Ar ages have been determined for 16 summit lava flows and three englacial tephra layers erupted from Mount Erebus. The summit region is composed of at least one or possibly two superimposed calderas that have been filled by post-caldera lava flows ranging in age from 17 ± 8 to 1 ± 5 ka. Dated pre-caldera summit flows display two age populations at 95 ± 9 to 76 ± 4 ka and 27 ± 3 to 21 ± 4 ka of samples with tephriphonolite and phonolite compositions, respectively. A caldera-collapse event occurred between 25 and 11 ka. An older caldera-collapse event is likely to have occurred between 80 and 24 ka. Two englacial tephra layers from the flanks of Mount Erebus have been dated at 71 ± 5 and 15 ± 4 ka. These layers stratigraphically bracket 14 undated tephra layers, and predate 19 undated tephra layers, indicating that small-scale explosive activity has occurred throughout the late Pleistocene and Holocene eruptive history of Mount Erebus. A distal, englacial plinian-fall tephra sample has an age of 39 ± 6 ka and may have been associated with the older of the two caldera-collapse events. A shift in magma composition from tephriphonolite to phonolite occurred at around 36 ka.

  9. 40Ar/39Ar dating of the eruptive history of Mount Erebus, Antarctica: Summit flows, tephra, and caldera collapse

    USGS Publications Warehouse

    Harpel, C.J.; Kyle, P.R.; Esser, R.P.; McIntosh, W.C.; Caldwell, D.A.

    2004-01-01

    Eruptive activity has occurred in the summit region of Mount Erebus over the last 95 ky, and has included numerous lava flows and small explosive eruptions, at least one plinian eruption, and at least one and probably two caldera-forming events. Furnace and laser step-heating 40Ar/39Ar ages have been determined for 16 summit lava flows and three englacial tephra layers erupted from Mount Erebus. The summit region is composed of at least one or possibly two superimposed calderas that have been filled by post-caldera lava flows ranging in age from 17 ?? 8 to 1 ?? 5 ka. Dated pre-caldera summit flows display two age populations at 95 ?? 9 to 76 ?? 4 ka and 27 ?? 3 to 21 ??4 ka of samples with tephriphonolite and phonolite compositions, respectively. A caldera-collapse event occurred between 25 and 11 ka. An older caldera-collapse event is likely to have occurred between 80 and 24 ka. Two englacial tephra layers from the flanks of Mount Erebus have been dated at 71 ?? 5 and 15 ?? 4 ka. These layers stratigraphically bracket 14 undated tephra layers, and predate 19 undated tephra layers, indicating that small-scale explosive activity has occurred throughout the late Pleistocene and Holocene eruptive history of Mount Erebus. A distal, englacial plinian-fall tephra sample has an age of 39 ?? 6 ka and may have been associated with the older of the two caldera-collapse events. A shift in magma composition from tephriphonolite to phonolite occurred at around 36 ka. ?? Springer-Verlag 2004.

  10. Ionization satellites of the ArHe dimer

    SciTech Connect

    Miteva, Tsveta; Klaiman, Shachar; Gokhberg, Kirill; Gromov, Evgeniy V.

    2014-05-28

    Ionization satellites are key ingredients in the control of post ionization processes such as molecular dissociation and interatomic Coulombic decay. Here, using the high-level ab initio method of multi-reference configuration interaction up to triple excitations, we study the potential energy curves (PECs) of the ionization satellites of the ArHe dimer. With this model system, we demonstrate that the simple model used in alkaline earth metal and rare gas complexes to describe the satellites as a Rydberg electron moving on top of a dicationic core does not fully hold for the rare gas clusters. The more complex valence structure in the rare gas atom leads to the mixing of different electronic configurations of the dimer. This prevents one from assigning a single dicationic parent state to some of the ionization satellites. We further analyze the structure of the different PECs, demonstrating how the density of the Rydberg electron is reflected in the structure of the PEC wherever the simple model is applicable.

  11. Ar-40/Ar-39 Ages of Maskelynite Grains from ALHA 77005

    NASA Technical Reports Server (NTRS)

    Turrin, B.; Park, J.; Herzog, G. F.; Lindsay, F. N.; Delaney, J. S.; Nyquist, L. E.; Swisher, C., III

    2013-01-01

    We present Ar-40/Ar-39 measurements for twelve small (20-60 micro-g) maskelynite samples from the heavily shocked martian meteorite ALHA 77005. The reported modal composition for ALHA 77005 is 50-60% olivine (Fa28), 30-40% pyroxene (Wo5Fs23En72), approx.8% maskelynite (An53), and approx.2% opaques by volume [1]). The meteorite is usually classified as a lherzolite. Previous Studies - Ar-40/Ar-39 results from previous work display disturbed release spectra [2,3]. In study [2], Ar-40/Ar-39 measurements on a 52-mg whole-rock sample produced an extremely disturbed release spec-trum, with all calculated apparent ages > 1 Ga, (Fig. 1). In a subsequent study [3], a light and a dark phase were analyzed. A 2.3-mg sample of the light, relatively low-K phase produced a disturbed release spectrum. For the first 20% of the Ar-39(sub K), most of the apparent ages exceeded >1 Ga; the remaining 80% yielded ages between 0.3-0.5 Ga. The integrated age for this phase is 0.9 Ga.

  12. Ar-Ar Impact Heating Ages of Eucrites and Timing of the LHB

    NASA Technical Reports Server (NTRS)

    Bogard, Donald; Garrison, Daniel

    2009-01-01

    Eucrites and howardites, more than most meteorite types, show extensive impact resetting of their Ar-39-Ar-40 (K-Ar) ages approximately equal to 3.4-4.1 Ga ago, and many specimens show some disturbance of other radiometry chronometers as well. Bogard (1995) argued that this age resetting occurred on Vesta and was produced by the same general population of objects that produced many of the lunar impact basins. The exact nature of the lunar late heavy bombardment (LHB or 'cataclysm') remains controversial, but the timing is similar to the reset ages of eucrites. Neither the beginning nor ending time of the lunar LHB is well constrained. Comparison of Ar-Ar ages of brecciated eucrites with data for the lunar LHB can resolve both the origin of these impactors and the time period over which they were delivered to the inner solar system. This abstract reports some new Ar-Ar age data for eucrites, obtained since the authors' 1995 and 2003 papers.

  13. Moving Beyond the Androgen Receptor (AR): Targeting AR-Interacting Proteins to Treat Prostate Cancer

    PubMed Central

    Foley, Christopher; Mitsiades, Nicholas

    2016-01-01

    Medical or surgical castration serve as the backbone of systemic therapy for advanced and metastatic prostate cancer, taking advantage of the importance of androgen signaling in this disease. Unfortunately, resistance to castration emerges almost universally. Despite the development and approval of new and more potent androgen synthesis inhibitors and androgen receptor (AR) antagonists, prostate cancers continue to develop resistance to these therapeutics, while often maintaining their dependence on the AR signaling axis. This highlights the need for innovative therapeutic approaches that aim to continue disrupting AR downstream signaling, but are orthogonal to directly targeting the AR itself. In this review, we discuss the preclinical research that has been done, as well as clinical trials for prostate cancer, on inhibiting several important families of AR interacting proteins, including chaperones (such as HSP90 and FKBP52), pioneer factors (including FOXA1 and GATA-2), and AR transcriptional coregulators such as the p160 steroid receptor coactivators (SRCs) SRC-1, SRC-2, SRC-3, as well as lysine deacetylases (KDACs) and lysine acetyltransferases (KATs). Researching the effect of, and developing new therapeutic agents that target, the AR signaling axis is critical to advancing our understanding of prostate cancer biology, and to continuing to improve treatments for prostate cancer and for overcoming castration-resistance. PMID:26728473

  14. Moving Beyond the Androgen Receptor (AR): Targeting AR-Interacting Proteins to Treat Prostate Cancer.

    PubMed

    Foley, Christopher; Mitsiades, Nicholas

    2016-04-01

    Medical or surgical castration serves as the backbone of systemic therapy for advanced and metastatic prostate cancer, taking advantage of the importance of androgen signaling in this disease. Unfortunately, resistance to castration emerges almost universally. Despite the development and approval of new and more potent androgen synthesis inhibitors and androgen receptor (AR) antagonists, prostate cancers continue to develop resistance to these therapeutics, while often maintaining their dependence on the AR signaling axis. This highlights the need for innovative therapeutic approaches that aim to continue disrupting AR downstream signaling but are orthogonal to directly targeting the AR itself. In this review, we discuss the preclinical research that has been done, as well as clinical trials for prostate cancer, on inhibiting several important families of AR-interacting proteins, including chaperones (such as heat shock protein 90 (HSP90) and FKBP52), pioneer factors (including forkhead box protein A1 (FOXA1) and GATA-2), and AR transcriptional coregulators such as the p160 steroid receptor coactivators (SRCs) SRC-1, SRC-2, SRC-3, as well as lysine deacetylases (KDACs) and lysine acetyltransferases (KATs). Researching the effect of-and developing new therapeutic agents that target-the AR signaling axis is critical to advancing our understanding of prostate cancer biology, to continue to improve treatments for prostate cancer and for overcoming castration resistance.

  15. Fabrication of ZnO photonic crystals by nanosphere lithography using inductively coupled-plasma reactive ion etching with CH{sub 4}/H{sub 2}/Ar plasma on the ZnO/GaN heterojunction light emitting diodes

    SciTech Connect

    Chen, Shr-Jia; Chang, Chun-Ming; Kao, Jiann-Shiun; Chen, Fu-Rong; Tsai, Chuen-Horng

    2010-07-15

    This article reports fabrication of n-ZnO photonic crystal/p-GaN light emitting diode (LED) by nanosphere lithography to further booster the light efficiency. In this article, the fabrication of ZnO photonic crystals is carried out by nanosphere lithography using inductively coupled plasma reactive ion etching with CH{sub 4}/H{sub 2}/Ar plasma on the n-ZnO/p-GaN heterojunction LEDs. The CH{sub 4}/H{sub 2}/Ar mixed gas gives high etching rate of n-ZnO film, which yields a better surface morphology and results less plasma-induced damages of the n-ZnO film. Optimal ZnO lattice parameters of 200 nm and air fill factor from 0.35 to 0.65 were obtained from fitting the spectrum of n-ZnO/p-GaN LED using a MATLAB code. In this article, we will show our recent result that a ZnO photonic crystal cylinder has been fabricated using polystyrene nanosphere mask with lattice parameter of 200 nm and radius of hole around 70 nm. Surface morphology of ZnO photonic crystal was examined by scanning electron microscope.

  16. Investigation of Deep Ocean Circulation and Mixing Using Ar-39 (Invited)

    NASA Astrophysics Data System (ADS)

    Smethie, W. M.; Schlosser, P.

    2013-12-01

    Ar-39 is a radioactive noble gas that forms in the atmosphere by cosmic ray interaction with Ar-40. It has a half-life of 269 years and its production rate in the atmosphere has varied no more than 7% during the past 1000 years. It enters the surface ocean with an average equilibration time of about one month and thus the entire surface ocean, except for ice covered regions at high latitudes, is in quasi-equilibrium with the atmospheric Ar-39:Ar ratio. The well known input to the ocean, radioactive decay constant and chemical inertness make Ar-39 an ideal tracer of circulation and mixing in the deep ocean, where anthropogenic transient tracers such as CFCs and tritium have not yet penetrated. However, due to the difficult measurement, only about 125 oceanic Ar-39 samples have been measured to date. This was done by counting the decays of Ar-39 atoms and required a half liter of argon gas per sample, extracted from about 1500 liters of water. The 125 samples that have been measured provide a glimpse of the information that can be gained from Ar-39 observations. In the Pacific Ocean three vertical profiles show a decrease in Ar-39 from the surface mixed layer through the thermocline to a minimum at intermediate depths and an increase from there to the bottom. This reflects formation of bottom water around the Antarctic continent, spreading of this water northward and upwelling and mixing into intermediate depths. The lowest concentration was 6×4% modern which is equivalent to a 900-1600 year isolation time from the surface. In the Atlantic Ocean newly formed North Atlantic Deep Water has an Ar-39 concentration of about 85% modern compared to 55% modern for newly formed Antarctic Bottom Water and reach values as low as about 40% modern in the interior reflecting the more rapid ventilation of the deep Atlantic Ocean relative to the deep Pacific Ocean. In the Arctic Ocean the mean residence time of deep water in the Nansen, Amundsen and Makarov Basins based on Ar-39

  17. 40Ar/39Ar age of the Manson impact structure, Iowa, and correlative impact ejecta in the Crow Creek member of the Pierre Shale (Upper Cretaceous), South Dakota and Nebraska

    USGS Publications Warehouse

    Izett, G.A.; Cobban, W.A.; Dalrymple, G.B.; Obradovich, J.D.

    1998-01-01

    A set of 34 laser total-fusion 40Ar/39Ar analyses of sanidine from a melt layer in crater-fill deposits of the Manson impact structure in Iowa has a weighted-mean age of 74.1 ?? 0.1 Ma. This age is about 9.0 m.y. older than 40Ar/39Ar ages of shocked microcline from the Manson impact structure reported previously by others. The 74.1 Ma age of the sanidine, which is a melt product of Precambrian microcline clasts, indicates that the Manson impact structure played no part in the Cretaceous-Tertiary (K-T) mass extinction at 64.5 Ma. Moreover, incremental-heating 40Ar/39Ar ages of the sanidine show that it is essentially free of excess 40Ar and has not been influenced by postcrystallization heating or alteration. An age spectrum of the matrix of the melt layer shows effects of 39Ar recoil, including older ages in the low-temperature increments and younger ages in the high-temperature increments. At 17 places in eastern South Dakota and Nebraska, shocked quartz and feldspar grains are concentrated in the lower part of the Crow Creek Member of the Pierre Shale (Upper Cretaceous). The grains are largest (3.2 mm) in southeastern South Dakota and decrease in size (0.45 mm) to the northwest, consistent with the idea that the Manson impact structure was their source. The ubiquitous presence of shocked grains concentrated in a thin calcarenite at the base of the Crow Creek Member suggests it is an event bed recording an instant of geologic time. Ammonites below and above the Crow Creek Member limit its age to the zone of Didymoceras nebrascense of earliest late Campanian age. Plagioclase from a bentonite bed in this zone in Colorado has a 40Ar/39Ar age of 74.1 ?? 0.1 Ma commensurate with our sanidine age of 74.1 Ma for the Manson impact structure. 40Ar/39Ar ages of bentonite beds below and above the Crow Creek are consistent with our 74.1 ?? 0.1 Ma age for the Manson impact structure and limit its age to the interval ?? 74.5 0.1 to 73.8 ?? 0.1 Ma. Recently, two origins for the

  18. Potassium Isotopic Compositions of NIST Potassium Standards and 40Ar/39Ar Mineral Standards

    NASA Technical Reports Server (NTRS)

    Morgan, Leah; Tappa, Mike; Ellam, Rob; Mark, Darren; Higgins, John; Simon, Justin I.

    2013-01-01

    Knowledge of the isotopic ratios of standards, spikes, and reference materials is fundamental to the accuracy of many geochronological methods. For example, the 238U/235U ratio relevant to U-Pb geochronology was recently re-determined [1] and shown to differ significantly from the previously accepted value employed during age determinations. These underlying values are fundamental to accurate age calculations in many isotopic systems, and uncertainty in these values can represent a significant (and often unrecognized) portion of the uncertainty budget for determined ages. The potassium isotopic composition of mineral standards, or neutron flux monitors, is a critical, but often overlooked component in the calculation of K-Ar and 40Ar/39Ar ages. It is currently assumed that all terrestrial materials have abundances indistinguishable from that of NIST SRM 985 [2]; this is apparently a reasonable assumption at the 0.25per mille level (1s) [3]. The 40Ar/39Ar method further relies on the assumption that standards and samples (including primary and secondary standards) have indistinguishable 40K/39K values. We will present data establishing the potassium isotopic compositions of NIST isotopic K SRM 985, elemental K SRM 999b, and 40Ar/39Ar biotite mineral standard GA1550 (sample MD-2). Stable isotopic compositions (41K/39K) were measured by the peak shoulder method with high resolution MC-ICP-MS (Thermo Scientific NEPTUNE Plus), using the accepted value of NIST isotopic SRM 985 [2] for fractionation [4] corrections [5]. 40K abundances were measured by TIMS (Thermo Scientific TRITON), using 41K/39K values from ICP-MS measurements (or, for SRM 985, values from [2]) for internal fractionation corrections. Collectively these data represent an important step towards a metrologically traceable calibration of 40K concentrations in primary 40Ar/39Ar mineral standards and improve uncertainties by ca. an order of magnitude in the potassium isotopic compositions of standards.

  19. Whole-Rock 40Ar/39Ar Step-heating Analyses, Problems and Potential

    NASA Astrophysics Data System (ADS)

    Boehnke, P.; Harrison, M.; Heizler, M. T.; Lovera, O. M.; Warren, P. H.

    2015-12-01

    Whole-rock 40Ar/39Ar step-heating analyses of extra-terrestrial materials are used to constrain the impact history of the inner solar system, the formation age of the Moon, and timing of paleomagnetic fields. Despite the importance of knowing the timing of these important events, the samples we have in hand are usually disturbed through mixing, (multiple?) impact events, and perhaps recoil loss. Extra-terrestrial 40Ar/39Ar data are typically interpreted through the assignment of essentially arbitrary plateau ages rather than through a robust physical model. Although the use of models capable of quantitatively assessing diffusive 40Ar* loss in extra-terrestrial samples has been around for nearly 50 years, this early advance has been widely ignored. Here we present implications of applying a robust, multi-activation energy, multi-diffusion domain model to step-heated 40Ar/39Ar data, with temperature cycling. Our findings show that for even a single heating event, "plateau" ages are unlikely to record meaningful ages. Further, if the sample has experienced multiple heating events or contains inherited clasts, recovering a unique solution may be impossible. Indeed the most readily interpretable portion of the age spectrum is the early heating steps which represents a maximum age estimate of the last re-heating event. Our results challenge the chronologic validity of 40Ar/39Ar "plateau" ages and by extension the hypotheses that are based on this data (e.g., the Late Heavy Bombardment). Future work will require new analytical procedures, interpretative frameworks, and (potentially) the combination of multiple chronometers to derive a robust impact history for the early solar system.

  20. Neutron detection by scintillation of noble-gas excimers

    NASA Astrophysics Data System (ADS)

    McComb, Jacob Collin

    Neutron detection is a technique essential to homeland security, nuclear reactor instrumentation, neutron diffraction science, oil-well logging, particle physics and radiation safety. The current shortage of helium-3, the neutron absorber used in most gas-filled proportional counters, has created a strong incentive to develop alternate methods of neutron detection. Excimer-based neutron detection (END) provides an alternative with many attractive properties. Like proportional counters, END relies on the conversion of a neutron into energetic charged particles, through an exothermic capture reaction with a neutron absorbing nucleus (10B, 6Li, 3He). As charged particles from these reactions lose energy in a surrounding gas, they cause electron excitation and ionization. Whereas most gas-filled detectors collect ionized charge to form a signal, END depends on the formation of diatomic noble-gas excimers (Ar*2, Kr*2,Xe* 2) . Upon decaying, excimers emit far-ultraviolet (FUV) photons, which may be collected by a photomultiplier tube or other photon detector. This phenomenon provides a means of neutron detection with a number of advantages over traditional methods. This thesis investigates excimer scintillation yield from the heavy noble gases following the boron-neutron capture reaction in 10B thin-film targets. Additionally, the thesis examines noble-gas excimer lifetimes with relationship to gas type and gas pressure. Experimental data were collected both at the National Institute of Standards and Technology (NIST) Center for Neutron Research, and on a newly developed neutron beamline at the Maryland University Training Reactor. The components of the experiment were calibrated at NIST and the University of Maryland, using FUV synchrotron radiation, neutron imaging, and foil activation techniques, among others. Computer modeling was employed to simulate charged-particle transport and excimer photon emission within the experimental apparatus. The observed excimer

  1. Experiences from the ARS croplands CEAP program

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The multi-agency Conservation Effects Assessment Project (CEAP) within USDA produced a number of lessons that should be applicable to the use of landscape approaches to place bioenergy crops. Results from the ARS Croplands Watersheds CEAP, the NRCS CEAP, and the NIFA CEAP Watershed Assessment Studie...

  2. Lignocellulosic Biofuels: Bioenergy Research at ARS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The growth and long-term viability of bioenergy production in the Nation are impeded by a number of technical and commercial barriers. Agricultural Research Service (ARS) addresses technical barriers and does so by leveraging its strengths and unique capabilities to (1) pursue technical barriers th...

  3. 78 FR 56979 - Arkansas Disaster # AR-00065

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-16

    ... From the Federal Register Online via the Government Publishing Office ] SMALL BUSINESS ADMINISTRATION Arkansas Disaster AR-00065 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  4. 78 FR 9448 - Arkansas Disaster #AR-00061

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-08

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Arkansas Disaster AR-00061 AGENCY: U.S. Small Business Administration. ACTION: Notice SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  5. 76 FR 42154 - Arkansas Disaster #AR-00050

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-18

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Arkansas Disaster AR-00050 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Arkansas...

  6. 76 FR 42155 - Arkansas Disaster #AR-00051

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-18

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Arkansas Disaster AR-00051 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  7. 78 FR 39821 - Arkansas Disaster #AR-00064

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-02

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Arkansas Disaster AR-00064 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  8. 75 FR 7637 - Arkansas Disaster #AR-00040

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-22

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Arkansas Disaster AR-00040 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Arkansas dated...

  9. 75 FR 30872 - Arkansas Disaster # AR-00043

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-02

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Arkansas Disaster AR-00043 AGENCY: U.S. Small Business Administration. ACTION: Notice SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Arkansas dated...

  10. 76 FR 27140 - Arkansas Disaster # AR-00049

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-10

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Arkansas Disaster AR-00049 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  11. 76 FR 27139 - Arkansas Disaster #AR-00048

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-10

    ... From the Federal Register Online via the Government Publishing Office ] SMALL BUSINESS ADMINISTRATION Arkansas Disaster AR-00048 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Arkansas...

  12. The ChArMEx database

    NASA Astrophysics Data System (ADS)

    Ferré, Hélène; Belmahfoud, Nizar; Boichard, Jean-Luc; Brissebrat, Guillaume; Cloché, Sophie; Descloitres, Jacques; Fleury, Laurence; Focsa, Loredana; Henriot, Nicolas; Mière, Arnaud; Ramage, Karim; Vermeulen, Anne; Boulanger, Damien

    2015-04-01

    The Chemistry-Aerosol Mediterranean Experiment (ChArMEx, http://charmex.lsce.ipsl.fr/) aims at a scientific assessment of the present and future state of the atmospheric environment in the Mediterranean Basin, and of its impacts on the regional climate, air quality, and marine biogeochemistry. The project includes long term monitoring of environmental parameters , intensive field campaigns, use of satellite data and modelling studies. Therefore ChARMEx scientists produce and need to access a wide diversity of data. In this context, the objective of the database task is to organize data management, distribution system and services, such as facilitating the exchange of information and stimulating the collaboration between researchers within the ChArMEx community, and beyond. The database relies on a strong collaboration between ICARE, IPSL and OMP data centers and has been set up in the framework of the Mediterranean Integrated Studies at Regional And Locals Scales (MISTRALS) program data portal. ChArMEx data, either produced or used by the project, are documented and accessible through the database website: http://mistrals.sedoo.fr/ChArMEx. The website offers the usual but user-friendly functionalities: data catalog, user registration procedure, search tool to select and access data... The metadata (data description) are standardized, and comply with international standards (ISO 19115-19139; INSPIRE European Directive; Global Change Master Directory Thesaurus). A Digital Object Identifier (DOI) assignement procedure allows to automatically register the datasets, in order to make them easier to access, cite, reuse and verify. At present, the ChArMEx database contains about 120 datasets, including more than 80 in situ datasets (2012, 2013 and 2014 summer campaigns, background monitoring station of Ersa...), 25 model output sets (dust model intercomparison, MEDCORDEX scenarios...), a high resolution emission inventory over the Mediterranean... Many in situ datasets

  13. Discordant K-Ar and young exposure dates for the Windjana sandstone, Kimberley, Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Vasconcelos, P. M.; Farley, K. A.; Malespin, C. A.; Mahaffy, P.; Ming, D.; McLennan, S. M.; Hurowitz, J. A.; Rice, Melissa S.

    2016-10-01

    K-Ar and noble gas surface exposure age measurements were carried out on the Windjana sandstone, Kimberley region, Gale Crater, Mars, by using the Sample Analysis at Mars instrument on the Curiosity rover. The sandstone is unusually rich in sanidine, as determined by CheMin X-ray diffraction, contributing to the high K2O concentration of 3.09 ± 0.20 wt % measured by Alpha-Particle X-ray Spectrometer analysis. A sandstone aliquot heated to 915°C yielded a K-Ar age of 627 ± 50 Ma. Reheating this aliquot yielded no additional Ar. A second aliquot heated in the same way yielded a much higher K-Ar age of 1710 ± 110 Ma. These data suggest incomplete Ar extraction from a rock with a K-Ar age older than 1710 Ma. Incomplete extraction at 900°C is not surprising for a rock with a large fraction of K carried by Ar-retentive K-feldspar. Likely, variability in the exact temperature achieved by the sample from run to run, uncertainties in sample mass estimation, and possible mineral fractionation during transport and storage prior to analysis may contribute to these discrepant data. Cosmic ray exposure ages from 3He and 21Ne in the two aliquots are minimum values given the possibility of incomplete extraction. However, the general similarity between the 3He (57 ± 49 and 18 ± 32 Ma, mean 30 Ma) and 21Ne (2 ± 32 and 83 ± 24 Ma, mean 54 Ma) exposure ages provides no evidence for underextraction. The implied erosion rate at the Kimberley location is similar to that reported at the nearby Yellowknife Bay outcrop.

  14. Growth of mica porphyroblasts under low-grade metamorphism - A Taiwanese case using in-situ40Ar/39Ar laser microprobe dating

    NASA Astrophysics Data System (ADS)

    Chen, Chih-Tung; Chan, Yu-Chang; Lo, Ching-Hua; Lu, Chia-Yu

    2016-11-01

    Mica porphyroblasts, a common metamorphic microstructure, are analyzed in the slate belt of northern Taiwan where large fish-like growths are found within a meta-pyroclastics. With constraints on the time-temperature history from deposition through peak metamorphic state to exhumation, in-situ40Ar/39Ar laser microprobe dating was carried out on muscovite and corrensite fibers of mm-scale mica porphyroblasts grown on a pressure-solution seam. Because the peak metamorphic temperature and the porphyroblast formation condition (∼250 °C) remained far below the closure temperature of the K-Ar radioisotope system in muscovite, and the absence of muscovite in the mafic protolith, the dating results likely document the growth of the mica porphyroblast fabrics. The syn-kinematic nature of the analyzed porphyroblasts is confirmed by the ∼6 to ∼2.5 Ma growth ages, suggesting that the host rock was continuously deformed during the earlier two-thirds of the Taiwan Orogeny. The pattern of fiber growth, in contrast to outward-decreasing ages normally observed in peripheral recrystallization, appears random and resembles void fills in boudin openings. We postulate that syntaxial crack-seal following tensile micro-boudinage, along with slips on sub-grain boundaries, as a viable mechanism for the development of mica porphyroblasts and fish especially in lower-grade metamorphic rocks.

  15. Negative ion gas-phase chemistry of arenes.

    PubMed

    Danikiewicz, Witold; Zimnicka, Magdalena

    2016-01-01

    Reactions of aromatic and heteroaromatic compounds involving anions are of great importance in organic synthesis. Some of these reactions have been studied in the gas phase and are occasionally mentioned in reviews devoted to gas-phase negative ion chemistry, but no reviews exist that collect all existing information about these reactions. This work is intended to fill this gap. In the first part of this review, methods for generating arene anions in the gas phase and studying their physicochemical properties and fragmentation reactions are presented. The main topics in this part are as follows: processes in which gas-phase arene anions are formed, measurements and calculations of the proton affinities of arene anions, proton exchange reactions, and fragmentation processes of substituted arene anions, especially phenide ions. The second part is devoted to gas-phase reactions of arene anions. The most important of these are reactions with electrophiles such as carbonyl compounds and α,β-unsaturated carbonyl and related compounds (Michael acceptors). Other reactions including oxidation of arene anions and halogenophilic reactions are also presented. In the last part of the review, reactions of electrophilic arenes with nucleophiles are discussed. The best known of these is the aromatic nucleophilic substitution (SN Ar) reaction; however, other processes that lead to the substitution of a hydrogen atom in the aromatic ring are also very important. Aromatic substrates in these reactions are usually but not always nitroarenes bearing other substituents in the ring. The first step in these reactions is the formation of an anionic σ-adduct, which, depending on the substituents in the aromatic ring and the structure of the attacking nucleophile, is either an intermediate or a transition state in the reaction path. In the present review, we attempted to collect the results of both experimental and computational studies of the aforementioned reactions conducted since the

  16. Classification of munition fill using laser acoustics

    SciTech Connect

    Rodriguez, J.G.; Blackwood, L.G.

    1997-08-01

    Identification of a munition fill is easier if one can determine if there is fill material present (empty versus full), and if so, the phase (solid or liquid) of the fill. Previous munition inspection efforts by the Idaho National Engineering and Environmental Laboratory (INEEL) determined that resonance information could determine the fill. A portable, noncontacting laser-acoustic system was developed by INEEL that uses a low-power laser system to measure the container`s vibration characteristics in response to an acoustic excitation. These vibration characteristics were shown to be functions of the fill material and munition geometry. The laser acoustic system was used to characterize the fill of over one hundred 155-mm munitions. Additional research and development using this system is being performed for the Mobile Munitions Assessment System.

  17. Filling of orbital fluid management systems

    NASA Technical Reports Server (NTRS)

    Merino, F.; Blatt, M. H.; Thies, N. C.

    1978-01-01

    A study was performed with three objectives: (1) analyze fluid management system fill under orbital conditions; (2) determine what experimentation is needed; and (3) develop an experimental program. The fluid management system was a 1.06m (41.7 in) diameter pressure vessel with screen channel device. Analyses were conducted using liquid hydrogen and N2O4. The influence of helium and autogenous pressurization systems was considered. Analyses showed that fluid management system fill will be more difficult with a cryogen than with an earth storable. The key to a successful fill with cryogens is in devising techniques for filling without vent liquid, and removing trapped vapor from the screen device at tank fill completion. This will be accomplished with prechill, fill, and vapor condensation processes. Refill will require a vent and purge process, to dilute the residual helium, prior to introducing liquid. Neither prechill, chill, nor purge processes will be required for earth storables.

  18. Grain-filling problem in 'super' rice.

    PubMed

    Yang, Jianchang; Zhang, Jianhua

    2010-01-01

    Modern rice (Oryza sativa L.) cultivars, especially the newly bred 'super' rice, have numerous spikelets on a panicle with a large yield capacity. However, these cultivars often fail to achieve their high yield potential due to poor grain-filling of later-flowering inferior spikelets (in contrast to the earlier-flowering superior spikelets). Conventional thinking to explain the poor grain-filling is the consequence of carbon limitation. Recent studies, however, have shown that carbohydrate supply should not be the major problem because they have adequate sucrose at their initial grain-filling stage. The low activities of key enzymes in carbon metabolism may contribute to the poor grain-filling. Proper field practices, such as moderate soil drying during mid- and late grain-filling stages, could solve some problems in poor grain-filling. Further studies are needed by molecular approaches to investigate the signal transport, the hormonal action, the gene expressions, and the biochemical processes in inferior spikelets.

  19. Anatomy of an Inversion-46Ar

    NASA Astrophysics Data System (ADS)

    Zamick, Larry; Robinson, Shadow; Sharon, Yitzhak

    2011-04-01

    Two different interactions give very close results for properties of most even-even Ar isotopes, but for 46 Ar the results diverge. The interactions in question are a). WBT and b). SPDF-U. For 42 , 44 , 46 Ar the results are as follows : WBT E(21 +) (1 . 29 , 1 . 17 , 1 . 14) MeV E(22 +) (2 . 32 , 1 . 80 , 2 . 10) MeV g(21 +) (- . 095 , - . 022 , + . 100) g(22 +) (. 096 , . 045 , - . 070) SPDF-U E(21 +) (1 . 15 , 1 . 09 , 1 . 59) MeV E(22 +) (2 . 28 , 1 . 78 , 3 . 77) MeV g(21 +) (- . 084 , - . 040 , + . 513) g(22 +) (+ . 075 , + . 346 , + . 514). To understand the big differences for A = 46 we must look to the odd K isotopes. Consider the J = 3 / 2+-- J = 1 / 2+ splitting.(MeV) EXPT/WBT/SPDF-U A = 43 0 . 561 , 1 . 109 , 0 . 672 A = 45 0 . 474 , 0 . 871 , 0 . 345 A = 47 - 0 . 360 , 0 . 507 , - 0 . 320 A = 49 0 . 200 , 0 . 729 , 0 . 078 . We see that there is an inversion in the ``d3/2 -s1/2'' splitting for 47 K. The SPDF-U interaction successfully gives this inversion but WBT does not. Things are a bit different for B(E2, 01 - 21) . The values in e2 fm4 are WBT (338 , 425 , 541) /SPDF-U (351 , 357 , 525). Here the 2 interactions give very similar results. Both interactions yield a larger B(E2) for 46Ar than for 44Ar, as do previous calculations by others. This despite the fact that in single j A = 46 has a closed shell of neutrons. Most experimental measurements had the opposite--larger B(E2) for A = 44 than for A = 46 . But a most recent measurement by Mengone et al. disagrees with all previous measurements and agrees with the current shell model calculations.

  20. Cooperative Dynamics of AR and ER Activity in Breast Cancer.

    PubMed

    D'Amato, Nicholas C; Gordon, Michael A; Babbs, Beatrice; Spoelstra, Nicole S; Carson Butterfield, Kiel T; Torkko, Kathleen C; Phan, Vernon T; Barton, Valerie N; Rogers, Thomas J; Sartorius, Carol A; Elias, Anthony; Gertz, Jason; Jacobsen, Britta M; Richer, Jennifer K

    2016-11-01

    Androgen receptor (AR) is expressed in 90% of estrogen receptor alpha-positive (ER(+)) breast tumors, but its role in tumor growth and progression remains controversial. Use of two anti-androgens that inhibit AR nuclear localization, enzalutamide and MJC13, revealed that AR is required for maximum ER genomic binding. Here, a novel global examination of AR chromatin binding found that estradiol induced AR binding at unique sites compared with dihydrotestosterone (DHT). Estradiol-induced AR-binding sites were enriched for estrogen response elements and had significant overlap with ER-binding sites. Furthermore, AR inhibition reduced baseline and estradiol-mediated proliferation in multiple ER(+)/AR(+) breast cancer cell lines, and synergized with tamoxifen and fulvestrant. In vivo, enzalutamide significantly reduced viability of tamoxifen-resistant MCF7 xenograft tumors and an ER(+)/AR(+) patient-derived model. Enzalutamide also reduced metastatic burden following cardiac injection. Finally, in a comparison of ER(+)/AR(+) primary tumors versus patient-matched local recurrences or distant metastases, AR expression was often maintained even when ER was reduced or absent. These data provide preclinical evidence that anti-androgens that inhibit AR nuclear localization affect both AR and ER, and are effective in combination with current breast cancer therapies. In addition, single-agent efficacy may be possible in tumors resistant to traditional endocrine therapy, as clinical specimens of recurrent disease demonstrate AR expression in tumors with absent or refractory ER.