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Sample records for ar gas filled

  1. Simulation model for analyzing voltage-current characteristics of the barrier type lamp filled with Hg-Ar gas

    NASA Astrophysics Data System (ADS)

    Watanabe, Yoshio; Yamaguchi, Tomohiro; Imada, Ryosuke

    2013-09-01

    The simulation model for DBD lamp filled with Hg-Ar gas is studied. The straight tube filled with Hg and Ar gases is employed as a lamp. Three kinds of applied voltage waveforms at high frequency are applied between the pair of stripe electrodes attached on the outside of the tube. One dimensional model is employed. Ionization frequency based on Townsend ionization coefficient is employed in this model. A try-and-error method is employed to estimate the value of each coefficient, and the calculated waveform is compared with the measured current waveform. The values by which the most similar current waveform to the measurement is obtained are selected as appropriate values. Using these coefficient values, the discharge current waveforms by the applying voltage with triangular waveform and trapezoidal waveforms are calculated and compared with the measured current waveforms. Good agreements between the calculation and the measurement in discharge current waveform are obtained for three types of applied voltage waveform. Then, the distributions of electric field, electron density and ion density in the discharge space are calculated. It is shown that the space charge layer is formed on the glass tube wall and ionization takes place mainly in the space charge layer. Professor

  2. Pressurized gas filled tendons

    SciTech Connect

    Silcox, W. H.

    1985-06-04

    Pressurized gas filled tubular tendons provide a means for detecting leaks therein. Filling the tendon with a gaseous fluid provides increased buoyancy and reduces the weight supported by the buoyant structure. The use of a corrosion inhibiting gaseous fluid reduces the corrosion of the interior tendon wall.

  3. 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.

  4. 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.

  5. Gas-filled hohlraum fabrication

    SciTech Connect

    Salazar, M.A.; Gobby, P.L.; Foreman, L.R.; Bush, H. Jr.; Gomez, V.M.; Moore, J.E.; Stone, G.F.

    1995-09-01

    Los Alamos National Laboratory (LANL) researchers have fabricated and fielded gas-filled hohlraums at the Lawrence Livermore National Laboratory (LLNL) Nova laser. Fill pressures of 1--5 atmospheres have been typical. We describe the production of the parts, their assembly and fielding. Emphasis is placed on the production of gas-tight polyimide windows and the fielding apparatus and procedure.

  6. 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.

  7. 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.

  8. Cryostat Filling Limitations for Proposed Ar Dewar Pressure Increase

    SciTech Connect

    Dixon, K.; Wu, J.; /Fermilab

    1991-07-23

    In order to significantly decrease the amount of time required to fill the cryostats, it is desired to raise the setpoint of the 'operating' relief valve on the argon storage dewar to 20 psig from its existing 16 psig setting. This additional pressure increases the flow to the cryostats and will overwhelm the relief capacity if the temperature of the modules within these vessels is warm enough. Using some conservative assumptions and simple calculations within this note, the maximum average temperature that the modules within each cryostat can be at prior to filling from the storage dewar with liquid argon is at least 290 K.

  9. 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.

  10. Pressure-controlled phase matching to third harmonic in Ar-filled hollow-core photonic crystal fiber.

    PubMed

    Nold, J; Hölzer, P; Joly, N Y; Wong, G K L; Nazarkin, A; Podlipensky, A; Scharrer, M; Russell, P St J

    2010-09-01

    We report tunable third-harmonic generation (THG) in an Ar-filled hollow-core photonic crystal fiber, pumped by broadband <2 microJ, 30 fs pulses from an amplified Ti:sapphire laser system. The overall dispersion is precisely controlled by balancing the negative dielectric susceptibility of the waveguide against the positive susceptibility of the gas. We demonstrate THG to a higher-order guided mode and show that the phase-matched UV wavelength is tunable by adjusting the gas pressure. PMID:20808370

  11. Bright spatially coherent wavelength-tunable deep-UV laser source using an Ar-filled photonic crystal fiber.

    PubMed

    Joly, N Y; Nold, J; Chang, W; Hölzer, P; Nazarkin, A; Wong, G K L; Biancalana, F; Russell, P St J

    2011-05-20

    We report on the spectral broadening of ~1 μJ 30 fs pulses propagating in an Ar-filled hollow-core photonic crystal fiber. In contrast with supercontinuum generation in a solid-core photonic crystal fiber, the absence of Raman and unique pressure-controlled dispersion results in efficient emission of dispersive waves in the deep-UV region. The UV light emerges in the single-lobed fundamental mode and is tunable from 200 to 320 nm by varying the pulse energy and gas pressure. The setup is extremely simple, involving <1 m of a gas-filled photonic crystal fiber, and the UV signal is stable and bright, with experimental IR to deep-UV conversion efficiencies as high as 8%. The source is of immediate interest in applications demanding high spatial coherence, such as laser lithography or confocal microscopy. PMID:21668228

  12. 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.

  13. 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.

  14. 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.

  15. Super-insulating gas-filled panels

    SciTech Connect

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

    1990-08-01

    This paper presents the design, materials characteristics, and thermal performance of a new insulating material. Development of this material is motivated by the need for non-CFC based high performance insulations with applications for refrigerator/freezer and building walls. This super insulating gas filled panel technology achieves R-values of between 8 hr-ft{sup 2}-F/Btu per inch and 15 hr-ft{sup 2}-F/Btu per inch (one to two times that of CFC blown foams and two to four times that of fiberglass insulations) at estimated costs of $0.40--$1.50/in-ft{sup 2}. Prototypes have been built using commercially available materials and components, tested by the developers, and sent to an independent laboratory for independent thermal performance testing. 2 refs., 4 figs., 1 tab.

  16. 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.

  17. Research and Development of a New Gas-Filled Recoil Separator GARIS-II

    NASA Astrophysics Data System (ADS)

    Kaji, Daiya; Morimoto, Kouji; Haba, Hiromitsu; Wakabayashi, Yasuo; Kudou, Yuki; Hung, Minghui; Goto, Shin-ichi; Murakami, Masashi; Goto, Naoya; Koyama, Takumi; Tamura, Nobuyuki; Tsuto, Shouhei; Sumita, Takayuki; Tanaka, Kengo; Takeyama, Mirei; Yamaki, Sayaka; Morita, Kosuke

    The results of the recent on-line test experiment using a gas-filled recoil ion separator GARIS-II, whose main purpose is to perform the so-called hot fusion reactions to produce superheavy elements, are presented. Reaction products via 169Tm(40Ar,4n)205Fr and 208Pb(40Ar,3n)245Fm were collected by the focal plane detection system of GARIS-II with high efficiency of 47% for 205Fr and 63% for 245Fm under low background condition.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Hot Gas Testing Results of Stagnant Volume Filling Through a Back-Filled RSRM Nozzle Joint

    NASA Technical Reports Server (NTRS)

    Prince, Andrew S.

    1999-01-01

    Silicone rubber is back-filled into RSW nozzle joints after assembly. A possible artifact of this process is the formation of small pathways through this filter leading to sensitive sealing materials within the joint. At motor ignition, hot gases fill the stagnant volumes within the joint through this path. A series of 14 test has been completed studying this scenario and providing anchoring data for thermal/flow models. Parameters such as gas path cross section, gas path length, gas path materials, fill volume size, and post path gas spreading prior to unpingement on seal material, have been investigated. Tests were accomplished using geometry similar to RSRM nozzle joint 4 with attached volumes replicating the free volume and flow friction in the actual hardware. The test hardware simulated 8 inches of the full-scale circumference. Testing has pointed to changes required in model boundary condition assumptions and gas dynamics corrections for gas paths of this size and geometry. Areas ,where this date has provided improvement in analysis models will be covered as well as model inadequacies that require separate specialized efforts. Questions remaining after this testing and a possible direction for future testing will be suggested.

  3. 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.

  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. 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.

  6. 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.

  7. 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%. PMID:22516716

  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. Polysulfone hollow fiber gas separation membranes filled with submicron particles.

    PubMed

    Bhardwaj, V; Macintosh, A; Sharpe, I D; Gordeyev, S A; Shilton, S J

    2003-03-01

    Three different fillers, carbon black (CB), vapor grown carbon fibers (VGCF), and TiO(2), were incorporated into polysulfone spinning solutions with the intention of producing highly selective membranes with enhanced mechanical strength. The effect of filler presence on gas permeation characteristics, mechanical strength (bursting pressure), and morphology was investigated and compared to unfilled membranes. As well as studying filler types, the influence of CB filler concentration on membrane performance was also examined. For all filler types (at a concentration of 5%w/w), the pressure-normalized flux of O(2), N(2), and CH(4) was greater in the composite than in the unfilled membranes. The CO(2) pressure-normalized flux was only greater in the TiO(2) composite membranes. For CB and VGCF, the CO(2) pressure-normalized flux was reduced compared with unfilled membranes. Three CB concentrations were investigated (2, 5, and 10%w/w). For O(2), N(2), and CH(4), pressure-normalized flux peaked at 5%w/w CB. CO(2) exhibited the opposite trend, showing a minimum pressure-normalized flux at 5%w/w. Considering O(2)/N(2) and CO(2)/CH(4) gas pairs and the various filled membrane categories, only the O(2)/N(2) selectivity of the 2%w/w CB filled membranes was higher than that of the unfilled fibers-all other selectivities were lower. In terms of CB concentration, selectivity was a minimum at the intermediate concentration of 5%w/w. All the filled membrane types exhibited greater mechanical strength (bursting pressure) than unfilled fibers apart from the 5%w/w VGCF composites. The 2%w/w CB composites were the strongest. Electron microscopy showed no visible differences in general morphology between the various filled and unfilled membranes. PMID:12783827

  10. Architecture in outer space. [multilayer shell systems filled with gas

    NASA Technical Reports Server (NTRS)

    Pokrovskiy, G. I.

    1974-01-01

    Mulilayer thin film structures consisting of systems of shells filled with gas at some pressure are recommended for outer space structures: Large mirrors to collect light and radio waves, protection against meteoric impact and damage, and for connectors between state space stations in the form of orbital rings. It is projected that individual orbital rings will multiply and completely seal a star trapping its high temperature radiation and transforming it into low temperature infrared and short wave radio emission; this radiation energy could be utilized for technological and biological processes.

  11. Insulation diagnostics for high-frequency gas-filled equipment

    SciTech Connect

    Aksenov, Y.P.; Letitskaya, L.V.; Lyapin, A.G.; Popkov, V.I.; Sakharov, A.E.; Tarasov, A.I.

    1984-01-01

    Two types of high-voltage gas filled devices intended for energy applications, whose models may be represented as a lumped capacitance or a long line, are used as examples to consider a method for extracting weak signals produced by defects in the apparatus from the background picked up from equipment operating at the substation. It is shown that by comparing signals sent by sensors responding to variations in the electric and magnetic fields and installed at the input and output of the device it is possible to extract and reliably register the signal associated with partial discharges.

  12. Scaling laws for the atomic Xe laser in Ne/Ar/Xe and He/Ar/Xe gas mixtures

    SciTech Connect

    Vogel, M.S.; Jong, W.; Kushner, S.

    1992-12-01

    The atomic Xe laser oscillates on 6 transitions (1.73 {mu}m - 3.7 {mu}m) between the 5d and 6p manifolds. Ar/Xe gas mixtures usually produce the highest laser efficiencies at 1.73 {mu}m, however gas heating from energy loading can reduce or terminate laser output due to an increase in the electron density. One is therefore motivated to increase the gas pressure by adding a lighter rare gas (He or Ne). The scaling of the atomic Xe laser using Ne/Ar/Xe and He/Ar/Xe gas mixtures have been investigated using a computer model. Addition of Ne significantly alters the kinetic pathways leading to increased pumping of the 6p manifold by dissociative recombination of Xe{sub 2}{sup +} thereby decreasing laser power. Increasing the heat capacity of the mixture by adding Ne can regain some of this loss at high energy loading. He addition is less disruptive with respect to the ion chemistry, but preferential quenching of the lower laser levels causes osciallation to be dominantly at 2.03 {mu}m.

  13. 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.

  14. 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.

  15. 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.

  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. 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.

  18. A compact gas-filled avalanche counter for DANCE

    DOE PAGESBeta

    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.

  19. Development of a portable gas-filled ionization chamber

    NASA Astrophysics Data System (ADS)

    Chae, K. Y.; Cha, S. M.; Gwak, M. S.

    2014-02-01

    A new portable gas-filled ionization chamber has been designed and constructed at the Physics Department of Sung Kyun Kwan University. To overcome the maximum count rate of ˜105 particles per second of a conventional ionization chamber, which utilizes a Frisch grid, and to enhance the portability of a detector, we adopted the design of multiple electrodes and modified it from the original designs by Kimura et al. and Chae et al. The new design utilizes a stack of multiple electrodes installed perpendicular to the optical beam axis. This configuration provides a fast response time for the detector, which is essential for high-rate counting. The device has been tested with a 241Am ( t 1/2 = 432.2 years) radioactive α source, which mainly emits 5.486-MeV (branching ratio of 85%) and 5.443-MeV (branching ratio of 13%) α particles. An energy resolution of 6.3% was achieved.

  20. 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. PMID:26939033

  1. Comparison of the surface characteristics of polypropylene films treated by Ar and mixed gas (Ar/O2) atmospheric pressure plasma.

    PubMed

    Kwon, Oh-June; Myung, Sung-Woon; Lee, Chang-Soo; Choi, Ho-Suk

    2006-03-15

    In an attempt to modify the hydrophobic surface properties of polypropylene (PP) films, this study examined the optimum process parameters of atmospheric pressure plasma (APP) using Ar gas. Under optimized conditions, the effects of a mixed gas (Ar/O2) plasma treatment on the surface-free energy of a PP film were investigated as a function of the O2 content. The polar contribution of the surface-free energy of the PP film increased with increasing O2 content in the gas mixture. However, slightly more oxygen-containing polar functional groups such as CO, CO, and COO were introduced on the PP film surface by the Ar gas only rather than by the Ar/O2 gas mixture. In addition, AFM analysis showed that the Ar plasma treatment of the PP film produced the smoothest surface as a result of the relatively homogeneous etching process. PMID:16310799

  2. Improving the efficiency of high harmonic generation (HHG) by Ne-admixing into a pure Ar gas medium

    NASA Astrophysics Data System (ADS)

    Seo, Hyun Ook; Arion, Tiberiu; Roth, Friedrich; Ramm, Daniel; Lupulescu, Cosmin; Eberhardt, Wolfgang

    2016-04-01

    Laser-based higher-order harmonic generation has been investigated extensively in the past two decades. The current manuscript deals with the high harmonic generation (HHG) outputs from a gas-filled waveguide when using mixtures of two rare gases (Ar and Ne) as nonlinear media. We find that the efficiency of the HHG process can be optimized by changing the pressure or alternatively the mixing ratio of the two gases. This is attributed to the fact that both of these parameters have an effect on the phase-matching in the waveguide. These observations are especially useful when phase matching in a gas jet is concerned, where the absolute local pressure of the gas media cannot be controlled as readily as in a capillary-based HHG setup.

  3. 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.

  4. Method and apparatus for processing filling gas from a coke oven battery

    SciTech Connect

    Polenz, J.; Wagner, H.

    1981-08-11

    An improved coke oven battery and an improved method for production of coke and byproducts are provided. The filling gas escaping during the filling of the oven chambers with coal is initially rendered inert by admixing flue gas. Then the resulting gas mixture of filling gas and flue gas is withdrawn via a conduit fed with flushing liquor from the coke oven gas off-take main and is added to the raw coke oven gas after the coke oven gas off-take main. The tar and coal containing flushing liquor coming from the filling gas conduit is fed back to the coke oven gas off-take main after removal of the tar.

  5. Theoretical rovibrational analysis of the covalent noble gas compound ArNH+

    NASA Astrophysics Data System (ADS)

    Novak, Carlie M.; Fortenberry, Ryan C.

    2016-04-01

    Noble gasses can make covalent bonds. This has been clearly shown for ArH+ as is evidenced by the observation of this molecule ubiquitously in the interstellar medium. In order to augment the list of potential noble gas molecules, highly-accurate quartic field methods are employed here to analyze the ArNH+ radical cation for the first time. This study is in line with previous examinations of ArOH+, ArH2+, and ArH3+. It is shown here that the Arsbnd N bond strength falls below the Arsbnd O bond energy in ArOH+ but in line with that from ArH2+ indicating that ArNH+ could certainly be synthesized in the lab or, potentially, in nature. In order to aid in the search for this noble gas molecular cation, spectroscopic constants, fundamental vibrational frequencies, absorption intensities, and the center-of-mass dipole moment are provided at high-level in order to augment our understanding of noble gas chemistry.

  6. Analytical modeling of the gas-filling dynamics in photonic crystal fibers.

    PubMed

    Dicaire, Isabelle; Beugnot, Jean-Charles; Thévenaz, Luc

    2010-08-20

    We present useful expressions predicting the filling time of gaseous species inside photonic crystal fibers. Based on the theory of diffusion, this gas-filling model can be applied to any given fiber geometry or length by calculating diffusion coefficients. This was experimentally validated by monitoring the filling process of acetylene gas in several fiber samples of various geometries and lengths. The measured filling times agree well, within +/-15%, with the predicted values for all fiber samples. In addition, the pressure dependence of the diffusion coefficient was experimentally verified by filling a given fiber sample with acetylene gas at various pressures. Finally, optimized conditions for gas-light interaction are determined by considering the gas flow dynamics in the design of microstructured fibers for gas detection and all-fiber gas cell applications. PMID:20733632

  7. Automation of experiments at Dubna Gas-Filled Recoil Separator

    NASA Astrophysics Data System (ADS)

    Tsyganov, Yu. S.

    2016-01-01

    Approaches to solving the problems of automation of basic processes in long-term experiments in heavy ion beams of the Dubna Gas-Filled Recoil Separator (DGFRS) facility are considered. Approaches in the field of spectrometry, both of rare α decays of superheavy nuclei and those for constructing monitoring systems to provide accident-free experiment running with highly radioactive targets and recording basic parameters of experiment, are described. The specific features of Double Side Silicon Strip Detectors (DSSSDs) are considered, special attention is paid to the role of boundary effects of neighboring p-n transitions in the "active correlations" method. An example of an off-beam experiment attempting to observe Zeno effect is briefly considered. Basic examples for nuclear reactions of complete fusion at 48Ca ion beams of U-400 cyclotron (LNR, JINR) are given. A scenario of development of the "active correlations" method for the case of very high intensity beams of heavy ions at promising accelerators of LNR, JINR, is presented.

  8. 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.

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

    SciTech Connect

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

    2008-09-15

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

  10. 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.

  11. Waste Package Neutron Absorber, Thermal Shunt, and Fill Gas Selection Report

    SciTech Connect

    V. Pasupathi

    2000-01-28

    Materials for neutron absorber, thermal shunt, and fill gas for use in the waste package were selected using a qualitative approach. For each component, selection criteria were identified; candidate materials were selected; and candidates were evaluated against these criteria. The neutron absorber materials evaluated were essentially boron-containing stainless steels. Two candidates were evaluated for the thermal shunt material. The fill gas candidates were common gases such as helium, argon, nitrogen, carbon dioxide, and dry air. Based on the performance of each candidate against the criteria, the following selections were made: Neutron absorber--Neutronit A978; Thermal shunt--Aluminum 6061 or 6063; and Fill gas--Helium.

  12. Extent of gas hydrate filled fracture planes: Implications for in situ methanogenesis and resource potential

    NASA Astrophysics Data System (ADS)

    Cook, Ann E.; Goldberg, David

    2008-08-01

    High-angle gas hydrate filled fracture planes were identified along a 31 m interval in logging while drilling images in two holes located ~11 m apart drilled during the Indian National Gas Hydrate Program Expedition 01, offshore India. Using Monte Carlo simulations to account for uncertainty in hole location, hole deviation, strike and dip, we assert with 95% confidence that the fracture planes in the two holes are not the same. The gas hydrate filled fracture planes likely only extend a few meters laterally from each borehole and occur in an isolated interval in the middle of the gas hydrate stability zone. This suggests gas generated microbially within in the gas hydrate stability zone may have supplied the gas hydrate-filled fracture interval. Production of methane from these reservoirs using conventional methods may be quite challenging.

  13. 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.

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

    SciTech Connect

    Weber, S. V.; Casey, D. T.; Eder, D. C.; Pino, J. E.; Smalyuk, V. A.; 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.; and others

    2014-11-15

    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 D{sup 3}He 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 D{sup 3}He capsule yields are matched, as well as other metrics for both capsule types.

  15. FABRICATION OF GAS-FILLED TUNGSTEN-COATED GLASS SHELLS

    SciTech Connect

    NIKROO,A; BAUGH,W; STEINMAN,D.A

    2003-06-01

    OAK-B135 Deuterium (D{sub 2}) filled glass shells coated with a high Z element are needed for high energy density (HED) experiments by researchers at Los Alamos National Laboratory. They report here on our initial attempt to produce such shells. Glass shells made using the drop tower technique were coated with gold, palladium or tungsten, or a mixture of two of these elements. It was found that gold and palladium coatings did not stick well to the glass and resulted in poor or delaminated films. Tungsten coatings resulted in films suitable for these targets. Bouncing of shells during coating resulted in uniform tungsten coatings, but the surface of such coatings were filled with small nodules. Proper agitation of shells using a tapping technique resulted in smooth films with minimal particulate contamination. For coating rates of {approx} 0.15 {micro}m/hr coatings with {approx} 2 nm RMS surface finish could be deposited. The surface roughness of coatings at higher rates, 0.7 {micro}m/hr, was considerably worse ({approx} 100 nm RMS). The columnar structure of the coatings allowed permeation filling of the tungsten coated glass shells with deuterium at 300 C.

  16. 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.

  17. 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.

  18. The Management of Gas-Filled Eyes in the Emergency Department

    PubMed Central

    Lim, Lik Thai; Ah-kee, Elliott Y.; House, Beve P.; Walker, Jonathan D.

    2014-01-01

    Background. Intraocular gas bubbles are commonly used in retinal surgery. There are specific management guidelines that need to be followed to ensure surgical success, and there are also unique ophthalmic and systemic complications that can occur in such patients. Objective. To educate emergency department personnel about important issues in the management of patients who have a gas-filled eye following retinal surgery. Case Report. A patient with a gas-filled eye developed several complications including pain, severe vision loss, high-grade atrioventricular (AV) block, and pneumocephalus. Conclusion. Awareness of potential problems that may arise in patients with gas-filled eyes who present to the emergency department may help minimize morbidity for such patients. PMID:25525528

  19. 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.

  20. Space Charge Effects in a Gas Filled Penning Trap

    NASA Astrophysics Data System (ADS)

    Beck, D.; Ames, F.; Beck, M.; Bollen, G.; Delauré, B.; Schuurmans, P.; Schwarz, S.; Schmidt, P.; Severijns, N.; Forstner, O.

    2001-01-01

    Mass selective buffer gas cooling is a technique used for ions that are stored in a Penning trap. The technique can be applied to all elements and the mass resolving power achieved has proven to be sufficient to resolve isobars. When not only a few but 106 and more ions are stored at the same time, space charge starts to play a dominant role for the spatial distribution. In addition, the observed cyclotron frequency is shifted. This work investigates these effects by numerical calculations.

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

    SciTech Connect

    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.

  2. Towards a more universal understanding of radiation drive in gas-filled hohlraums

    NASA Astrophysics Data System (ADS)

    Jones, O. S.; Thomas, C. A.; Amendt, P. A.; Hall, G. N.; Izumi, N.; Barrios Garcia, M. A.; Berzak Hopkins, L. F.; Chen, H.; Dewald, E. L.; Hinkel, D. E.; Kritcher, A. L.; Marinak, M. M.; Meezan, N. B.; Milovich, J. L.; Moody, J. D.; Moore, A. S.; Patel, M. V.; Ralph, J. E.; Regan, S. P.; Rosen, M. D.; Schneider, M. B.; Sepke, S. M.; Strozzi, DJ; Turnbull, D. P.

    2016-05-01

    We have found that radiation-hydrodynamic calculations that use the high flux model assumptions [1] can accurately predict the radiation drive produced by a laser-heated hohlraum under certain conditions, but can not predict drive over a broad range of parameters (pulse energy, hohlraum gas fill density, hohlraum case-to-capsule ratio). In particular, the model is accurate for ∼7 ns long laser pulses used to implode capsules with high density carbon (HDC) ablators in hohlraums with helium fill gas densities of 0-0.6 mg/cc. By systematically varying the gas fill density from 0 to 1.6 mg/cc we found that the agreement with drive begins to diverge for fills > 0.85 mg/cc. This divergence from the model coincides with the onset of measureable SRS backscatter. In this same set of experiments the radiation drive symmetry inferred from the imploded shape of a gas-filled capsule is not predicted with this model. Finally, several possible fixes to the model to reduce the observed discrepancies are considered.

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

    NASA Astrophysics Data System (ADS)

    Kowalski, T. Z.

    2014-12-01

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

  4. Towards Complete and Realistic Studies for Rare-Gas Ionic Clusters, the Ar^+_3 Example

    NASA Astrophysics Data System (ADS)

    Gadea, Florent Xavier; Amarouche, Mohand

    1995-12-01

    The approach we have developped for the ab initio simulation of rare-gas ionic clusters is reviewed and applied to Ar^+_3. It is based on a DIM (Diatomic In Molecules) modelling for the electronic Hamiltonian and transition dipole moments, on approximate estimations for the absorption spectrum and a HWD (Hemiquantal dynamics with the Whole DIM basis) treatment of the fragmentation dynamics. The theoretical study is devoted to three basic aspects: the structure of the ions, their absorption spectrum and their fragmentation dynamics. These aspects correspond respectively to equilibrium, short time and long time dynamics. The results for Ar^+_3 are reviewed (structure, visible spectrum, photofragmentation dynamics, kinetic energy distribution of photofragments) and in addition new ones for the UV absorption spectrum are presented and discussed.

  5. 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.

  6. 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. PMID:24337290

  7. 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

  8. Measurement of void volume of a fuel rod and the exchange of occluded gases from mixed carbide fuel with filling gas helium

    NASA Astrophysics Data System (ADS)

    Rao, G. A. Rama; Kukarni, S. G.; Venugoopal, V.; Manchanda, V. K.; Goswami, G. L.

    1995-02-01

    The presence of gaseous impurities in the filling gas of a fuel pin is detriental to the thermal performance of a nuclear reactor fuel. The composition of the filling gas does not remain constant throughout the life of the fuel pin. The gas exchange phenomena that occur between the cover gas and impurity gases affect the fuel performance more severely in (U, Pu)O 2 fuel pin due to its inherently poor thermal conductivity than in advanced fuels such as mixed carbides and nitrides. In the present study the exchange phenomenon of the occluded gases present in our Fast Breeder Test Reactor (FBTR) fuel pellets [(U 0.30, Pu 0.70)C with 6500 ppm o] with the cover gas helium was observed as a function of time and temperature. Quantitative analysis of the released gases namely H 2, O 2 + Ar, N 2, CH 4 and CO was carried out at subambient pressure by gas chromatography. The void volume of the fuel element is determined experimentally by gas equilibration with known volume.

  9. Calibration of cosmogenic noble gas production in ordinary chondrites based on 36Cl-36Ar ages. Part 1: Refined produced rates for cosmogenic 21Ne and 38Ar

    NASA Astrophysics Data System (ADS)

    Dalcher, N.; Caffee, M. W.; Nishiizumi, K.; Welten, K. C.; Vogel, N.; Wieler, R.; Leya, I.

    2013-10-01

    We measured the concentrations and isotopic compositions of He, Ne, and Ar in bulk samples and metal separates of 14 ordinary chondrite falls with long exposure ages and high metamorphic grades. In addition, we measured concentrations of the cosmogenic radionuclides 10Be, 26Al, and 36Cl in metal separates and in the nonmagnetic fractions of the selected meteorites. Using cosmogenic 36Cl and 36Ar measured in the metal separates, we determined 36Cl-36Ar cosmic-ray exposure (CRE) ages, which are shielding-independent and therefore particularly reliable. Using the cosmogenic noble gases and radionuclides, we are able to decipher the CRE history for the studied objects. Based on the correlation 3He/21Ne versus 22Ne/21Ne, we demonstrate that, among the meteorites studied, only one suffered significant diffusive losses (about 35%). The data confirm that the linear correlation 3He/21Ne versus 22Ne/21Ne breaks down at high shielding. Using 36Cl-36Ar exposure ages and measured noble gas concentrations, we determine 21Ne and 38Ar production rates as a function of 22Ne/21Ne. The new data agree with recent model calculations for the relationship between 21Ne and 38Ar production rates and the 22Ne/21Ne ratio, which does not always provide unique shielding information. Based on the model calculations, we determine a new correlation line for 21Ne and 38Ar production rates as a function of the shielding indicator 22Ne/21Ne for H, L, and LL chondrites with preatmospheric radii less than about 65 cm. We also calculated the 10Be/21Ne and 26Al/21Ne production rate ratios for the investigated samples, which show good agreement with recent model calculations.

  10. 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.

  11. Modeling of drive-symmetry experiments in gas-filled hohlraums at Nova

    SciTech Connect

    Lindman, E.L.; Magelssen, G.R.; Delamater, E.L.; Hauer, A.A.; Wilde, B.H.; Powers, L.V.; Murphy, T.J.; Pollaine, S.M.; Suter, L.J.

    1995-05-01

    Experiments on capsule implosions in gas-filled hohlraums have been carried out on the NOVA Laser at Lawrence Livermore National Laboratory. Observed capsule shapes are more oblate than predicted using modeling methods which agree well with experiments in evacuated hohlraums. Improvements in modeling required to calculate these experiments and additional experiments are being pursued.

  12. 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.

  13. Direct Observation of a Gas Molecule (H2, Ar) Swallowed by C60

    SciTech Connect

    Sawa, H.; Kakiuchi, T.; Wakabayashi, Y.; Murata, Y.; Murata, M.; Komatsu, K.; Yakigaya, K.; Takagi, H.; Dragoe, N.

    2007-01-19

    Various types of endohedral fullerene complexes are known to date. The well known metallofullerenes are generally produced by arc-discharge method, but the use of such extremely drastic conditions is apparently not suitable for encapsulation of unstable molecules or gases. We recently succeeded in incorporation of a H2 molecule or an Ar atom in 100% into a C60. In order to observe the endohedral gas molecule directly, the X-ray diffraction analysis using synchrotron radiation were carried out. We observed a gas molecule encapsulated in each fullerene cage using structure analysis and the maximum entropy method. These gas molecules are floating inside of the hollow cavities and are completely isolated from the outside.

  14. Simulations of Recent Ar Gas Puff Radiation Sources on the ZR Generator

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    We present radiation-magnetohydrodynamic simulations of four recent Ar gas puff shots on the refurbished Z generator. The simulations using Mach2-TCRE are calculated in r-z geometry with a tabulated collisional radiative equilibrium model for the non-LTE ionization kinetics and radiation transport. The four shots were designed to study the effects upon the Ar K-shell radiation output due to a change in the initial gas puff distribution. The shots Z2604 and Z2605 had a double shell puff and a central jet. The shots Z2560 and Z2628 did not have a central jet. Calculated yields are close to experimental error-bars. Results will be presented for the impact of the initial gas puff distribution on the K-shell yield. 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.

  15. Deposition dynamics of droplet-free Si nanoparticles in Ar gas using laser ablation

    NASA Astrophysics Data System (ADS)

    Takeuchi, D.; Mizuta, T.; Makimura, T.; Yoshida, S.; Fujita, M.; Hata, K.; Shigekawa, H.; Murakami, K.

    2002-09-01

    Droplet-free deposition of Si nanoparticle films has been studied applying time-resolved imaging of Si nanoparticles formed by laser ablation of Si targets in Ar gas. We found that Si nanoparticles can be deposited not only on substrates facing to the targets but also on substrates placed beside the target. We further confirmed using a scanning tunneling microscope (STM), Si nanoparticles with sizes of 5-8 nm are deposited on substrates placed beside the target and using a scanning electron microscope (SEM) on the substrates, no droplets are observed.

  16. Site-Specific Fragmentation of Polystyrene Molecule Using Size-Selected Ar Gas Cluster Ion Beam

    NASA Astrophysics Data System (ADS)

    Moritani, Kousuke; Mukai, Gen; Hashinokuchi, Michihiro; Mochiji, Kozo

    2009-04-01

    The secondary ion mass spectrum (SIMS) of a polystyrene thin film was investigated using a size-selected Ar gas cluster ion beam (GCIB). The fragmentation in the SIM spectrum varied by kinetic energy per atom (Eatom); the Eatom dependence of the secondary ion intensity of the fragment species of polystyrene can be essentially classified into three types based on the relationship between Eatom and the dissociation energy of a specific bonding site in the molecule. These results indicate that adjusting Eatom of size-selected GCIB may realize site-specific bond breaking within a molecule.

  17. 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.

  18. 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.

  19. Photothermal effect in gas-filled hollow-core photonic bandgap fiber

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Jin, Wei; Cao, Yingchun; Ho, Hoi Lut

    2015-09-01

    We exploit photothermal effect in gas-filled hollow-core photonic bandgap fibers, and demonstrate remarkably sensitive all-fiber (acetylene) gas sensors with noise equivalent concentration of 1-3 parts-per-billion and an unprecedented dynamic range of nearly six orders of magnitude. These results are two to three orders of magnitude better than previous direct absorption-based optical fiber gas sensors. The realization of photothermal spectroscopy in fiber-optic format will allow a new class of sensors with ultra-sensitivity and selectivity, compact size, remote and multiplexed multi-point detection capability.

  20. 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.

  1. 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.

  2. 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

  3. Transient Beam Loading Effects in Gas-filled RF Cavities for a Muon Collider

    SciTech Connect

    Chung, M.; Tollestrup, A.; Yonehara, K.; Freemire, B.

    2013-06-01

    A gas-filled RF cavity can be an effective solution for the development of a compact muon ionization cooling channel. One possible problem expected in this type of cavity is the dissipation of significant RF power through the beam-induced plasmas accumulated inside the cavity (plasma loading). In addition, for the higher muon beam intensity, the effects of the beam itself on the cavity accelerating mode are non-negligible (beam loading). These beam- cavity interactions induce a transient phase which may be very harmful to the beam quality [1]. In this study, we estimate the transient voltage in a gas-filled RF cavity with both the plasma and conventional beam loading and discuss their compensation methods.

  4. Accuracy of the capillary approximation for gas-filled kagomé-style photonic crystal fibers.

    PubMed

    Finger, M A; Joly, N Y; Weiss, T; Russell, P St J

    2014-02-15

    Precise knowledge of the group velocity dispersion in gas-filled hollow-core photonic crystal fiber is essential for accurate modeling of ultrafast nonlinear dynamics. Here we study the validity of the capillary approximation commonly used to calculate the modal refractive index in kagomé-style photonic crystal fibers. For area-preserving core radius a(AP) and core wall thickness t, measurements and finite element simulations show that the approximation has an error greater than 15% for wavelengths longer than 0.56√(a(AP)t), independently of the gas-filling pressure. By introducing an empirical wavelength-dependent core radius, the range of validity of the capillary approximation is extended out to a wavelength of at least 0.98√(a(AP)t). PMID:24562215

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    A recent low gas-fill density (0.6 mg/cc 4He) 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 4He) 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. Demonstrated high performance of gas-filled rugby-shaped hohlraums on Omega

    SciTech Connect

    Philippe, F.; Villette, B.; Michel, P.; Petrasso, R.; Stoeckl, C.; Giraldez, E.; Tassin, V.; Depierreux, S.; Gauthier, P.; Masson-Laborde, P. E.; Monteil, M. C.; Seytor, P.; Lasinski, B.; Park, H. S.; Ross, J. S.; Amendt, P.; Döppner, T.; Hinkel, D. E.; Wallace, R.; Williams, E.; and others

    2014-07-15

    A direct experimental comparison of rugby-shaped and cylindrical shaped gas-filled hohlraums on the Omega laser facility demonstrates that higher coupling and minimal backscatter can be achieved in the rugby geometry, leading to significantly enhanced implosion performance. A nearly 50% increase of x-ray drive is associated with earlier bangtime and increase of neutron production. The observed drive enhancement from rugby geometry in this study is almost twice stronger than in previously published results.

  8. Demonstrated high performance of gas-filled rugby-shaped hohlraums on Omega

    SciTech Connect

    Philippe, F.; Tassin, V.; Depierreux, S.; Gauthier, P.; Masson-Laborde, P. E.; Monteil, M. C.; Seytor, P.; Villette, B.; Lasinski, B.; Park, H. S.; Ross, J. S.; Amendt, P.; Doeppner, T.; Hinkel, D. E.; Wallace, R.; Williams, E.; Michel, P.; Frenje, J.; Gatu-Johnson, M.; Li, C. K.; Petrasso, R.; Glebov, V.; Sorce, C.; Stoeckl, C.; Nikroo, A.; Giraldez, E.

    2014-07-25

    A direct experimental comparison of rugby-shaped and cylindrical shaped gas-filled hohlraums on the Omega laser facility demonstrates that higher coupling and minimal backscatter can be achieved in the rugby geometry, leading to significantly enhanced implosion performance. A nearly 50% increase of x-ray drive is associated with earlier bangtime and increase of neutron production. The observed drive enhancement from rugby geometry in this study is almost twice stronger than in previously published results.

  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. 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.

  11. Pressure optimization of high harmonic generation in a differentially pumped Ar or H2 gas jet

    NASA Astrophysics Data System (ADS)

    Sayrac, M.; Kolomenskii, A. A.; Anumula, S.; Boran, Y.; Hart, N. A.; Kaya, N.; Strohaber, J.; Schuessler, H. A.

    2015-04-01

    We experimentally studied the dependence of high harmonic generation in argon and molecular hydrogen on pressure changes in a gas jet that cause variations of the phase matching conditions and absorption. The study was performed at a peak laser intensity of ˜1.5 × 1014 W/cm2. To enable measurements over a wide range of pressures, we employed differential pumping with an additional cell (˜20 cm3 volume) enclosing the gas jet. By increasing the pressure in the gas jet up to a maximum of 1.5 bars with argon or 0.5 bars with hydrogen, we observed an increase in the high harmonic (HH) yield until an optimum pressure of 0.2 bars was reached for Ar, beyond which the output began decreasing. For H2, we observed an increase of the HH output up to the maximum pressure of 0.5 bars. This pressure-dependence study allowed us to achieve a tenfold enhancement in the high harmonic yield at the optimum pressure.

  12. Comparison of Two Potassium-Filled Gas-Controlled Heat Pipes

    NASA Astrophysics Data System (ADS)

    Bertiglia, F.; Iacomini, L.; Moro, F.; Merlone, A.

    2015-12-01

    Calibration by comparison of platinum resistance thermometers and thermocouples requires transfer media capable of providing very good short-term temperature uniformity and temperature stability over a wide temperature range. This paper describes and compares the performance of two potassium-filled gas-controlled heat pipes (GCHP) for operation over the range from 420° C to 900° C. One of the heat pipes has been in operation for more than 10 years having been operated at temperature for thousands of hours, while the other was commissioned in 2010 following recently developed improvements to both the design, assembly, and filling processes. It was found that the two devices, despite differences in age, structure, number of wells, and filling processes, realized the same temperatures within the measurement uncertainty. The results show that the potassium-filled GCHP provides a durable and high-quality transfer medium for performing thermometer calibrations with very low uncertainties, over the difficult high-temperature range from 420° C to 900° C.

  13. Determination of absorption coefficient based on laser beam thermal blooming in gas-filled tube.

    PubMed

    Hafizi, B; Peñano, J; Fischer, R; DiComo, G; Ting, A

    2014-08-01

    Thermal blooming of a laser beam propagating in a gas-filled tube is investigated both analytically and experimentally. A self-consistent formulation taking into account heating of the gas and the resultant laser beam spreading (including diffraction) is presented. The heat equation is used to determine the temperature variation while the paraxial wave equation is solved in the eikonal approximation to determine the temporal and spatial variation of the Gaussian laser spot radius, Gouy phase (longitudinal phase delay), and wavefront curvature. The analysis is benchmarked against a thermal blooming experiment in the literature using a CO₂ laser beam propagating in a tube filled with air and propane. New experimental results are presented in which a CW fiber laser (1 μm) propagates in a tube filled with nitrogen and water vapor. By matching laboratory and theoretical results, the absorption coefficient of water vapor is found to agree with calculations using MODTRAN (the MODerate-resolution atmospheric TRANsmission molecular absorption database) and HITRAN (the HIgh-resolution atmospheric TRANsmission molecular absorption database). PMID:25090334

  14. Detecting leaks in gas-filled pressure vessels using acoustic resonances

    NASA Astrophysics Data System (ADS)

    Gillis, K. A.; Moldover, M. R.; Mehl, J. B.

    2016-05-01

    We demonstrate that a leak from a large, unthermostatted pressure vessel into ambient air can be detected an order of magnitude more effectively by measuring the time dependence of the ratio p/f2 than by measuring the ratio p/T. Here f is the resonance frequency of an acoustic mode of the gas inside the pressure vessel, p is the pressure of the gas, and T is the kelvin temperature measured at one point in the gas. In general, the resonance frequencies are determined by a mode-dependent, weighted average of the square of the speed-of-sound throughout the volume of the gas. However, the weighting usually has a weak dependence on likely temperature gradients in the gas inside a large pressure vessel. Using the ratio p/f2, we measured a gas leak (dM/dt)/M ≈ - 1.3 × 10-5 h-1 = - 0.11 yr-1 from a 300-liter pressure vessel filled with argon at 450 kPa that was exposed to sunshine-driven temperature and pressure fluctuations as large as (dT/dt)/T ≈ (dp/dt)/p ≈ 5 × 10-2 h-1 using a 24-hour data record. This leak could not be detected in a 72-hour record of p/T. (Here M is the mass of the gas in the vessel and t is the time.)

  15. Detecting leaks in gas-filled pressure vessels using acoustic resonances.

    PubMed

    Gillis, K A; Moldover, M R; Mehl, J B

    2016-05-01

    We demonstrate that a leak from a large, unthermostatted pressure vessel into ambient air can be detected an order of magnitude more effectively by measuring the time dependence of the ratio p/f(2) than by measuring the ratio p/T. Here f is the resonance frequency of an acoustic mode of the gas inside the pressure vessel, p is the pressure of the gas, and T is the kelvin temperature measured at one point in the gas. In general, the resonance frequencies are determined by a mode-dependent, weighted average of the square of the speed-of-sound throughout the volume of the gas. However, the weighting usually has a weak dependence on likely temperature gradients in the gas inside a large pressure vessel. Using the ratio p/f(2), we measured a gas leak (dM/dt)/M ≈ - 1.3 × 10(-5) h(-1) = - 0.11 yr(-1) from a 300-liter pressure vessel filled with argon at 450 kPa that was exposed to sunshine-driven temperature and pressure fluctuations as large as (dT/dt)/T ≈ (dp/dt)/p ≈ 5 × 10(-2) h(-1) using a 24-hour data record. This leak could not be detected in a 72-hour record of p/T. (Here M is the mass of the gas in the vessel and t is the time.). PMID:27250456

  16. 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.

  17. Supercontinuum up-conversion via molecular modulation in gas-filled hollow-core PCF.

    PubMed

    Bauerschmidt, S T; Novoa, D; Trabold, B M; Abdolvand, A; Russell, P St J

    2014-08-25

    We report on the efficient, tunable, and selective frequency up-conversion of a supercontinuum spectrum via molecular modulation in a hydrogen-filled hollow-core photonic crystal fiber. The vibrational Q(1) Raman transition of hydrogen is excited in the fiber by a pump pre-pulse, enabling the excitation of a synchronous, collective oscillation of the molecules. This coherence wave is then used to up-shift the frequency of an arbitrarily weak, delayed probe pulse. Perfect phase-matching for this process is achieved by using higher order fiber modes and adjusting the pressure of the filling gas. Conversion efficiencies of ~50% are obtained within a tuning range of 25 THz. PMID:25321261

  18. Results from directly driven implosions of deuterated plastic shells filled with tritium gas

    NASA Astrophysics Data System (ADS)

    Grim, Gary; Casey, Daniel; Fincke, Jim; Pino, Jesse; Smalyuk, Vladimir; Steinkamp, Mike; Tipton, Robert

    2014-10-01

    Results from implosions of tritium filled plastic shells containing thin deuterated sub-layers, as well as comparisons with 1-D capsule only simulations will be reported. The implosions were directly driven using a square, 1 ns wide, 27 kJ laser pulse, provided by the Laboratory for Laser Energetics, University of Rochester, Rochester, NY. The 15 um thick, by 865 μm OD, CH capsules were fabricated with 1 μm thick, deuterated plastic layers, located either in direct contact with the tritium gas, or offset by a layer of CH. Neutrons produced by deuterium-tritium fusions signify atomic mixing between the deuterated shell and the gas payload, allowing for a detailed study of the dynamics of mix in 3-D implosions. Data has been collected on implosions from capsules with a depth of burial of 0, 1, and 2 um of CH, as well as non-deuterated control shots. Capsules were shot with two gas fill pressures, 4 and 10 atm., to provide information on mix as a function of convergence. We report nuclear and X-ray data collected from these experiments. Further, we present comparisons with, 1-D and 2-D, capsule only simulations. Prepared by LANL under Contract DE-AC-52-06-NA25396, TSPA.

  19. Explosion hazard analysis for an enclosure partially filled with a flammable gas

    SciTech Connect

    Ogle, R.A.

    1999-11-01

    The constant volume explosion of a flammable gas is one of the more common accidental explosions. The explosion pressure at the stoichiometric condition is approximately 50 times greater than the failure pressure of most industrial structures. Observations from accident scenes suggest that some explosions are caused by a quantity of fuel significantly less than the stoichiometric amount required to fill an enclosure. This paper presents a method for analyzing the explosion hazard in an enclosure which is only partially filled with a flammable gas. The method, called the adiabatic mixing model, is based on thermodynamics and can be used to calculate the minimum fuel quantity which will yield a specified explosion pressure. Results are presented for a set of representative fuels and are compared with alternative explosion models. The results demonstrate that catastrophic structural damage can be achieved with a volume of flammable gas which is less than one percent of the enclosure volume. The method can be a useful tool for both hazard analysis and accident investigations.

  20. Simulation of laser-plasma interaction experiments with gas-filled hohlraums on the LIL facility

    NASA Astrophysics Data System (ADS)

    Loiseau, P.; Masson-Laborde, P.-E.; Teychenné, D.; Monteil, M.-C.; Casanova, M.; Marion, D.; Tran, G.; Huser, G.; Rousseaux, C.; Hüller, S.; Héron, A.; Pesme, D.

    2016-03-01

    Laser-plasma interaction is a major issue for achieving ignition in inertial confinement fusion schemes, and still a major concern for the upcoming french laser mégajoule (LMJ) program. In order to mitigate the deleterious effects due to laser-plasma instabilities (LPI), clearly evidenced during the recent US National Ignition Campaign conducted on the National Ignition Facility, we use the LIL facility as a demonstrator for LPI studies. In this article, we focus on preliminary results regarding the propagation of a typical LMJ quadruplet through gas-filled hohlraums. Results on hohlraum energetics will then be discussed.

  1. 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.

  2. Tunable frequency-up/down conversion in gas-filled hollow-core photonic crystal fibers.

    PubMed

    Saleh, Mohammed F; Biancalana, Fabio

    2015-09-15

    Based on the interplay between photoionization and Raman effects in gas-filled photonic crystal fibers, we propose a new optical device to control frequency conversion of ultrashort pulses. By tuning the input-pulse energy, the output spectrum can be either down-converted, up-converted, or even frequency-shift compensated. For low input energies, the Raman effect is dominant and leads to a redshift that increases linearly during propagation. For larger pulse energies, photoionization starts to take over the frequency-conversion process and induces a strong blueshift. The fiber-output pressure can be used as an additional degree of freedom to control the spectrum shift. PMID:26371900

  3. Correction of aspect ratio dependency in deep silicon etch using SF6/C4F8/Ar gas mixture

    NASA Astrophysics Data System (ADS)

    Bates, Robert Lee

    The etch rate of deep features in silicon, such as trenches and vias, can vary significantly with the changing Aspect Ratio (AR) of the feature. Developing a better understanding of the complex volumetric and surface chemistry as well as the etching mechanisms controlling the Aspect Ratio Dependent Etch-rate (ARDE) continues to present research opportunities. Recall that ARDE is generally characterized by small AR features etching at faster rates than large AR features. The main causes of ARDE include Knudsen transport of neutrals into and out of the features as well as ion and neutral loss to the walls due to angular spread in the velocity distribution function and differential charging of insulating microstructures. This work focuses on using a continuous plasma process utilizing a gas mixture of SF6/C4F8/Ar to produce trenches of varying widths and depths. The experimental results were obtained using a Plasma-Therm Versaline processing system. Experiments were performed to show that the etch rate of low AR features can be reduced through the deposition of a passivation layer and thereby allow larger AR features to catch up. It is also possible to invert the ARDE in certain circumstances. We will present the insights we have gained into the ARDE process and the solutions we have tested.

  4. 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.

  5. 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.

  6. High energy gas fracture experiments in liquid-filled boreholes: potential geothermal application

    SciTech Connect

    Cuderman, J.F.; Chu, T.Y.; Jung, J.; Jacobson, R.D.

    1986-07-01

    High Energy Gas Fracturing is a tailored pulse fracturing technique which uses propellants to obtain controlled fracture initiation and extension. Borehole pressurization rates can be tailored, by suitable choice of propellants, to produce four or eight fractures radiating from the wellbore. High Energy Gas Fracture (HEGF) research is conducted at DOE's Nevada Test Site (NTS) in a tunnel complex where experiments can be done under realistic in situ stress conditions (1400 psi (9.7 MPa) overburden stress). Pressure measurements are made in the test borehole during all fracturing experiments. Experiments are mined back to provide direct observation of fracturing obtained. The initial objective of HEGF research was to develop multiple fracturing technology for application in gas well stimulation. HEGF research at NTS and in Devonian shale demonstration tests has resulted in a completed technology for multiple fracturing in uncased, liquid-free wellbores. Current resarch is directed toward extending the technique to liquid-filled boreholes for application in geothermal in addition to gas and oil wells. For liquid-free boreholes, multiple fracturing is specified in terms of pressure risetime required for a given borehole diameter. Propellants are mixed to achieve the desired risetime using a semiempirical mixing equation. The same techniques were successfully applied to fracturing in liquid-filled wellbores. However, the addition of liquid in the borehole results in a significantly more complicated fracturing behavior. Hydrodynamic effects are significant. Multiple fractures are initiated but only some propagated. Multiple- and hydraulic-type fracturing and wellbore crushing have been observed in the same experiment. The potential of using HEGB for geothermal well stimulation has been demonstrated through the present experiments. 18 refs., 40 figs., 4 tabs.

  7. Feasibility Study of Compact Gas-Filled Storage Ring for 6D Cooling of Muon Beams

    SciTech Connect

    A. Garren, J. Kolonlo

    2005-10-31

    The future of elementary particle physics in the USA depends in part on the development of new machines such as the International Linear Collider, Muon Collider and Neutrino Factories which can produce particle beams of higher energy, intensity, or particle type than now exists. These beams will enable the continued exploration of the world of elementary particles and interactions. In addition, the associated development of new technologies and machines such as a Muon Ring Cooler is essential. This project was to undertake a feasibility study of a compact gas-filled storage ring for 6D cooling of muon beams. The ultimate goal, in Phase III, was to build, test, and operate a demonstration storage ring. The preferred lattice for the storage ring was determined and dynamic simulations of particles through the lattice were performed. A conceptual design and drawing of the magnets were made and a study of the RF cavity and possible injection/ejection scheme made. Commercial applications for the device were investigated and the writing of the Phase II proposal completed. The research findings conclude that a compact gas-filled storage ring for 6D cooling of muon beams is possible with further research and development.

  8. The effect of mix on capsule yields as a function of shell thickness and gas fill

    SciTech Connect

    Bradley, P. A.

    2014-06-15

    An investigation of direct drive capsules with different shell thicknesses and gas fills was conducted to examine the amount of shock induced (Richtmyer-Meshkov) mix versus Rayleigh-Taylor mix from deceleration of the implosion. The RAGE (Eulerian) code with a turbulent mix model was used to model these capsules for neutron yields along with time-dependent mix amounts. The amount of Richtmyer-Meshkov induced mix from the shock breaking out of the shell is about 0.1 μg (0.15 μm of shell material), while the Rayleigh-Taylor mix is of order 1 μg and determines the mixed simulation yield. The simulations were able to calculate a yield over mix (YOM) ratio (experiment/mix simulation) between 0.5 and 1.0 for capsules with shell thicknesses ranging from 7.5 to 20 μm and with gas fills between 3.8 and 20 atm of D{sub 2} or DT. The simulated burn averaged T{sub ion} values typically lie with 0.5 keV of the data, which is within the measurement error. For capsules with shell thicknesses >25 μm, the YOM values drop to 0.10 ± 0.05, suggesting that some unmodeled effect needs to be accounted for in the thickest capsules.

  9. The structure of the Laser Entrance Hole in NIF Ignition gas-filled hohlraums

    NASA Astrophysics Data System (ADS)

    Schneider, M. B.; Doeppner, T.; Thomas, C. A.; Widmann, K.; MacLaren, S. A.; Meezan, N. B.; Bell, P. M.; Benedetti, L. R.; Bradley, D. K.; Callahan, D. A.; Eder, D.; Hammer, J. H.; Hinkel, D. E.; Jones, O. S.; Michel, P.; Milovich, J. L.; Moody, J. D.; Moore, A. J.; Park, H. S.; Ralph, J. E.; Regan, S. E.; Strozzi, D. J.; Town, R. P.

    2014-10-01

    At the National Ignition Facility (NIF), the energy from 192 laser beams is converted to an x-ray drive in a gas-filled hohlraum. The drive heats and implodes a fuel capsule. The laser beams enter the hohlraum via laser entrance holes (LEHs) at each end. The LEH size decreases as heated plasma from the LEH material blows radially inward but this is largely balanced by hot plasma in the laser deposition region pushing radially outward. Compared to models, the LEH size is larger than predicted. In addition, the plasma in the LEH region is hotter than predicted. Instead of being at the radiation temperature of about 300 eV, it is at an electron temperature of 1 to a few keV. The experimental measurements for this conclusion are discussed. Data on the LEH as a function of laser pulse shape, gas fill, and energy transfer are presented. This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  10. Continuous Measurements of Dissolved Ne, Ar, Kr, and Xe Ratios with a Field-Deployable Gas Equilibration Mass Spectrometer.

    PubMed

    Manning, Cara C; Stanley, Rachel H R; Lott, Dempsey E

    2016-03-15

    Noble gases dissolved in natural waters are useful tracers for quantifying physical processes. Here, we describe a field-deployable gas equilibration mass spectrometer (GEMS) that provides continuous, real-time measurements of Ne, Ar, Kr, and Xe mole ratios in natural waters. Gas is equilibrated with a membrane contactor cartridge and measured with a quadrupole mass spectrometer, after in-line purification with reactive metal alloy getters. We use an electron energy of 35 V for Ne to eliminate isobaric interferences, and a higher electron energy for the other gases to improve sensitivity. The precision is 0.7% or better and 1.0% or better for all mole ratios when the instrument is installed in a temperature-controlled environment and a variable-temperature environment, respectively. In the lab, the accuracy is 0.9% or better for all gas ratios using air as the only calibration standard. In the field (and/or at greater levels of disequilbrium), the accuracy is 0.7% or better for Ne/Kr, Ne/Ar, and Ar/Kr, and 2.5% or better for Ne/Xe, Ar/Xe, and Kr/Xe using air as the only calibration standard. The field accuracy improves to 0.6% or better for Ne/Xe, Ar/Xe, and Kr/Xe when the data is calibrated using discrete water samples run on a laboratory-based mass spectrometer. The e-folding response time is 90-410 s. This instrument enables the collection of a large number of continuous, high-precision and accuracy noble gas measurements at substantially reduced cost and labor compared to traditional methods. PMID:26854788

  11. Study of Damage of Gas-filled Spherical Pressure Vassel Subjected to Hypervelocity Impact by Space Debris with Different Velocity

    NASA Astrophysics Data System (ADS)

    Cai, Yuan; Pang, Baojun; Jia, Bin

    2013-08-01

    As an important component of spacecraft, if a gas-filled pressure vessel is impacted by space debris, it might occur even overall bursting. Spherical aluminum projectiles are used to simulate space debris impacting gas-filled spherical pressure vessel with hypervelocity. Projectiles impact places with the same thickness in different tests. By analyzing the maximum gas pressure of the spherical vessel, the inflation pressure is determined: 1.075MPa. By numerical simulation, the critical impact velocity to perforate the front wall is determined: 2.02mm ~ 2.31mm. As the projectile velocity increases, the damage patterns of the back wall are of different bulged outwards patterns.

  12. 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.

  13. 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.

  14. Mid-infrared gas filled photonic crystal fiber laser based on population inversion.

    PubMed

    Jones, Andrew M; Nampoothiri, A V Vasudevan; Ratanavis, Amarin; Fiedler, Tobias; Wheeler, Natalie V; Couny, François; Kadel, Rajesh; Benabid, Fetah; Washburn, Brian R; Corwin, Kristan L; Rudolph, Wolfgang

    2011-01-31

    We demonstrate for the first time an optically pumped gas laser based on population inversion using a hollow core photonic crystal fiber (HC-PCF). The HC-PCF filled with 12C2H2 gas is pumped with ~5 ns pulses at 1.52 μm and lases at 3.12 μm and 3.16 μm in the mid-infrared spectral region. The maximum measured laser pulse energy of ~6 nJ was obtained at a gas pressure of 7 torr with a fiber with 20 dB/m loss near the lasing wavelengths. While the measured slope efficiencies of this prototype did not exceed a few percent due mainly to linear losses of the fiber at the laser wavelengths, 25% slope efficiency and pulse energies of a few mJ are the predicted limits of this laser. Simulations of the laser's behavior agree qualitatively with experimental observations. PMID:21369049

  15. Implosion of reactor-size, gas-filled spherical shell targets driven by shaped pressure pulses

    SciTech Connect

    Piriz, A.R.; Atzeni, S. )

    1993-05-01

    The implosion of a family of reactor-size targets for inertial confinement fusion (ICF) is studied analytically and numerically. The targets consist of a deuterium--tritium (D--T) shell filled with D--T vapor and they are imploded by a multistep pressure pulse designed in such a way that the final hot spot is formed mainly from the initially gaseous fuel. The formation of the hot spot is described by means of a relatively simple model, and scaling laws for the quantities that characterize the state of the initially gaseous part of the fuel prior to ignition are derived. The results of the model are compared with one-dimensional fluid simulations, and good agreement is found. A parametric study of the fuel energy gain is then presented; the dependence of the gain and of the hot spot convergence ratio on the pulse parameters and on the filling gas density is analyzed. It is also shown that a substantial increase in the gain (for a given target and pulse energy) can be achieved by replacing the last step of the pulse with an exponential ramp.

  16. Raman-induced temporal condensed matter physics in gas-filled photonic crystal fibers.

    PubMed

    Saleh, Mohammed F; Armaroli, Andrea; Tran, Truong X; Marini, Andrea; Belli, Federico; Abdolvand, Amir; Biancalana, Fabio

    2015-05-01

    Raman effect in gases can generate an extremely long-living wave of coherence that can lead to the establishment of an almost perfect temporal periodic variation of the medium refractive index. We show theoretically and numerically that the equations, regulate the pulse propagation in hollow-core photonic crystal fibers filled by Raman-active gas, are exactly identical to a classical problem in quantum condensed matter physics - but with the role of space and time reversed - namely an electron in a periodic potential subject to a constant electric field. We are therefore able to infer the existence of Wannier-Stark ladders, Bloch oscillations, and Zener tunneling, phenomena that are normally associated with condensed matter physics, using purely optical means. PMID:25969278

  17. Convergent ablation measurements of plastic ablators in gas-filled rugby hohlraums on OMEGA

    NASA Astrophysics Data System (ADS)

    Casner, A.; Jalinaud, T.; Masse, L.; Galmiche, D.

    2015-10-01

    Indirect-drive implosions experiments were conducted on the Omega Laser Facility to test the performance of uniformly doped plastic ablators for Inertial Confinement Fusion. The first convergent ablation measurements in gas-filled rugby hohlraums are reported. Ignition relevant limb velocities in the range from 150 to 300 μm .n s-1 have been reached by varying the laser drive energy and the initial capsule aspect ratio. The measured capsule trajectory and implosion velocity are in good agreement with 2D integrated simulations and a zero-dimensional modeling of the implosions. We demonstrate experimentally the scaling law for the maximum implosion velocity predicted by the improved rocket model [Y. Saillard, Nucl. Fusion 46, 1017 (2006)] in the high-ablation regime case.

  18. Acetylene frequency references in gas-filled hollow optical fiber and photonic microcells.

    PubMed

    Wang, Chenchen; Wheeler, Natalie V; Fourcade-Dutin, Coralie; Grogan, Michael; Bradley, Thomas D; Washburn, Brian R; Benabid, Fetah; Corwin, Kristan L

    2013-08-01

    Gas-filled hollow optical fiber references based on the P(13) transition of the ν1+ν3 band of 12C2H2 promise portability with moderate accuracy and stability. Previous realizations are corrected (<1σ) by using proper modeling of a shift due to line-shape. To improve portability, a sealed photonic microcell is characterized on the 12C2H2 ν1+ν3 P(23) transition with somewhat reduced accuracy and stability. Effects of the photonic crystal fiber, including surface modes, are explored. Both polarization-maintaining (PM) and non-PM 7-cell photonic bandgap fiber are shown to be unsuitable for kilohertz-level frequency references. PMID:23913062

  19. 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.

  20. Structural Integrity of Gas-Filled Composite Overwrapped Pressure Vessels Subjected to Orbital Debris Impact

    NASA Astrophysics Data System (ADS)

    Telichev, Igor; Cherniaev, Aleksandr

    Gas-filled pressure vessels are extensively used in spacecraft onboard systems. During operation on the orbit they exposed to the space debris environment. Due to high energies they contain, pressure vessels have been recognized as the most critical spacecraft components requiring protection from orbital debris impact. Major type of pressurized containers currently used in spacecraft onboard systems is composite overwrapped pressure vessels (COPVs) manufactured by filament winding. In the present work we analyze the structural integrity of vessels of this kind in case of orbital debris impact at velocities ranging from 2 to 10 km/s. Influence of such parameters as projectile energy, shielding standoff, internal pressure and filament winding pattern on COPVs structural integrity has been investigated by means of numerical and physical experiments.

  1. 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.

  2. Filling factors and scale heights of the diffuse ionized gas in the Milky Way

    NASA Astrophysics Data System (ADS)

    Berkhuijsen, E. M.; Mitra, D.; Mueller, P.

    2006-01-01

    The combination of dispersion measures of pulsars, distances from the model of Cordes & Lazio (\\cite{cordes+lazio02}) and emission measures from the WHAM survey enabled a statistical study of electron densities and filling factors of the diffuse ionized gas (DIG) in the Milky Way. The emission measures were corrected for absorption and contributions from beyond the pulsar distance. For a sample of 157 pulsars at |b|>5° and 60° < ℓ < 360°, located in mainly interarm regions within about 3 kpc from the Sun, we find that: (1) The average volume filling factor along the line of sight /line{f}v and the mean density in ionized clouds /line{n}c are inversely correlated: /line{f}v(/line{n}c ) = (0.0184± 0.0011) /line{n}c{ -1.07± 0.03} for the ranges 0.03 < /line{n}c < 2 {cm-3 and 0.8 > /line{f}v > 0.01. This relationship is very tight. The inverse correlation of /line{f}v and /line{n}c causes the well-known constancy of the average electron density along the line of sight. As /line{f}v(z) increases with distance from the Galactic plane |z|, the average size of the ionized clouds increases with |z|. (2) For |z| < 0.9 kpc the local density in clouds nc (z) and local filling factor f(z) are inversely correlated because the local electron density ne (z) = f(z) nc (z) is constant. We suggest that f(z) reaches a maximum value of >0.3 near |z| = 0.9 kpc, whereas nc (z) continues to decrease to higher |z|, thus causing the observed flattening in the distribution of dispersion measures perpendicular to the Galactic plane above this height. (3) For |z| < 0.9 kpc the local distributions nc (z), f(z) and ne2(z) have the same scale height which is in the range 250 < h ⪉ 500 pc. (4) The average degree of ionization of the warm atomic gas /line{I}w (z) increases towards higher |z| similarly to /line{f}v (z). Towards |z| = 1 kpc, /line{f}v (z) = 0.24± 0.05 and /line{I}w (z) = 0.24± 0.02. Near |z| = 1 kpc most of the warm, atomic hydrogen is ionized.

  3. 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.

  4. Mechanism of Hydrogenated Microcrystalline Si Film Deposition by Magnetron Sputtering Employing a Si Target and H2/Ar Gas Mixture

    NASA Astrophysics Data System (ADS)

    Fukaya, Kota; Tabata, Akimori; Sasaki, Koichi

    2009-03-01

    The mechanism of hydrogenated microcrystalline silicon (µc-Si:H) film deposition by magnetron sputtering employing a Si target and H2/Ar gas mixture has been investigated by measuring Si and H atom densities in the gas phase by laser-induced fluorescence spectroscopy. The crystalline volume fraction of the film correlated positively with H atom density. The variation in Si atom density indicated the increase in sputtering yield from the Si target in the H2/Ar discharge. The surface of the Si target immersed in the H2/Ar discharge was hydrogenated. Therefore, it is reasonable to expect the production of SiHx molecules (typically SiH4) from the hydrogenated Si target via reactive ion etching. Since SiHx molecules produced from the target may function as a deposition precursor, the mechanism of µc-Si:H film deposition is considered to be similar to that of plasma-enhanced chemical vapor deposition (PECVD) employing a SiH4/H2 gas mixture. The advantage of magnetron sputtering deposition over PECVD is the production of SiHx molecules without using toxic, explosive SiH4.

  5. Formation of single-wall carbon nanotubes in Ar and nitrogen gas atmosphere by using laser furnace technique

    NASA Astrophysics Data System (ADS)

    Suzuki, S.; Asai, N.; Kataura, H.; Achiba, Y.

    2007-07-01

    The formation of single-wall carbon nanotubes (SWNTs) by using laser vaporization technique in different ambient gas atmosphere was investigated. SWNTs were prepared with Rh/Pd (1.2/1.2 atom%)-carbon composite rod in Ar and nitrogen gas atmosphere, respectively. Raman spectra of raw carbon materials including SWNTs and photoluminescence mapping of dispersed SWNTs in a surfactant solution demonstrate that the diameter distribution of SWNTs prepared in Ar atmosphere is narrower than those obtained by using CVD technique (e.g. HiPco nanotube), even when the ambient temperature is as high as 1150 ?C. It was also found that nitrogen atmosphere gives wider diameter distribution of SWNTs than that obtained with Ar atmosphere. Furthermore, the relative yield of fullerenes (obtained as byproducts) is investigated by using HPLC (high-performance liquid chromatography) technique. It was found that the relative yield of higher fullerenes becomes lower, when nitrogen is used as an ambient gas atmosphere. Based on these experimental findings, a plausible formation mechanism of SWNTs is discussed.

  6. 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.

  7. Effects of cavern spacing on the performance and stability of gas-filled storage caverns

    SciTech Connect

    Hoffman, E.L.

    1993-04-01

    Three-dimensional finite element analyses of gas-filled storage caverns in domal salt were performed to investigate the effects of cavern spacing on surface subsidence, storage loss, and cavern stability. The finite element model used for this study models a seven cavern storage field with one center cavern and six hexagonally spaced surrounding caverns. Cavern spacing is described in terms of the P/D ratio which is the pillar thickness (the width between two caverns) divided by the cavern diameter. With the stratigraphy and cavern size held constant, simulations were performed for P/D ratios of 6.0, 3.0, 2.0, 1.0, and 0.5. Ten year simulations were performed modeling a constant 400 psi gas pressure applied to the cavern lining. The calculations were performed using JAC3D, a three dimensional finite element analysis code for nonlinear quasistatic solids. For the range of P/D ratios studied, cavern deformation and storage volume were relatively insensitive to P/D ratio, while subsidence volume increased with increasing P/D ratio. A stability criterion which describes stability in terms of a limiting creep strain was used to investigate cavern stability. The stability criterion indicated that through-pillar instability was possible for the cases of P/D = 0.5 and 1.0.

  8. Preparation and characterization of gas-filled liposomes: can they improve oil recovery?

    PubMed

    Vangala, Anil; Morris, Robert; Bencsik, Martin; Perrie, Yvonne

    2007-01-01

    Although well known for delivering various pharmaceutical agents, liposomes can be prepared to entrap gas rather than aqueous media and have the potential to be used as pressure probes in magnetic resonance imaging (MRI). Using these gas-filled liposomes (GFL) as tracers, MRI imaging of pressure regions of a fluid flowing through a porous medium could be established. This knowledge can be exploited to enhance recovery of oil from the porous rock regions within oil fields. In the preliminary studies, we have optimized the lipid composition of GFL prepared using a simple homogenization technique and investigated key physico-chemical characteristics (size and the physical stability) and their efficacy as pressure probes. In contrast to the liposomes possessing an aqueous core which are prepared at temperatures above their phase transition temperature (T(c)), homogenization of the phospholipids such as 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-distearoyl-sn-glycero-3-phosphocoline (DSPC) in aqueous medium below their T(c) was found to be crucial in formation of stable GFL. DSPC based preparations yielded a GFL volume of more than five times compared to their DPPC counter part. Although the initial vesicle sizes of both DSPC and DPPC based GFL were about 10 microm, after 7 days storage at 25 degrees C, the vesicle sizes of both formulations significantly (p < 0.05) increased to 28.3 +/- 0.3 mum and 12.3 +/- 1.0 microm, respectively. When the DPPC preparation was supplemented with cholesterol at a 1:0.5 or 1:1 molar ratio, significantly (p < 0.05) larger vesicles were formed (12-13 microm), however, compared to DPPC only vesicles, both cholesterol supplemented formulations displayed enhanced stability on storage indicating a stabilizing effect of cholesterol on these gas-filled vesicles. In order to induce surface charge on the GFL, DPPC and cholesterol (1: 0.5 molar ratio) liposomes were supplemented with a cationic surfactant, stearylamine, at a molar

  9. Propagation dynamics of femtosecond laser pulses in a hollow fiber filled with argon: constant gas pressure versus differential gas pressure

    NASA Astrophysics Data System (ADS)

    Nurhuda, Muhammad; Suda, Akira; Midorikawa, Katsumi; Hatayama, Masatoshi; Nagasaka, Keigo

    2003-09-01

    We investigate the dynamics of femtosecond laser pulses propagating in a hollow fiber filled with argon, through a full numerical solution of the nonlinear Schrödinger equation. The simulation results show that, if the intensity is low and no ionization takes place, the spatial profile of the beam does not change very much so that its propagation model may be simplified to a one-dimensional model. If the intensity is high and ionization takes place, the spatial dynamics as well as temporal dynamics become very complicated because of self-focusing and defocusing. It is found that, for the same value of the B integral, self-focusing inside a hollow fiber can be substantially suspended by a differential gas pressure technique, where the gas pressure is set to be a minimum at the entrance and then increased with the propagation distance. Numerical simulations show that using such a technique, the energy transmitted during propagation inside hollow fiber is significantly enhanced, and the spatial phase is also improved.

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

    DOE PAGESBeta

    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.more » We present a comparison of three highly filled poly (ethyleneco- vinyl acetate) resins.« less

  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. 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.

  13. Shallow gas features in incised-valley fills (Rı´a de Vigo, NW Spain): a case study

    NASA Astrophysics Data System (ADS)

    Garcia-Gil, S.; Vilas, F.; Garcia-Garcia, A.

    2002-11-01

    Areas with gas accumulations and gas seeps, where gas escapes from the seabed to the water column have been mapped in the fill of a submarine incised valley, the Rı´a de Vigo. The various gas features have been classified into four types according to their specific seismic signatures: (1) acoustic blanket, (2) acoustic curtains, (3) acoustic columns, and (4) acoustic turbidity. At the same time, three types of gas escapes features have been distinguished: (1) acoustic plumes, (2) cloudy turbidity, and (3) pockmarks. Calculations indicate mean densities of 1.7 acoustic plumes km -2 and 1.6 pockmarks km -2. Estimations of the gas fluxes towards the atmosphere range from 144.37 to 4134.9 t yr -1. It is concluded that sedimentary facies is the main factor determining whether gas accumulates or seeps, and also determines the specific type of accumulation or seep at each location.

  14. Simulations of a Gas-Filled Helical Muon Beam Cooling Channel

    SciTech Connect

    K. Yonehara; D.M. Kaplan; K. Beard; S.A. Bogacz; Y.S. Derbenev; R.P. Johnson; K. Paul; T.J. Roberts

    2005-05-16

    A helical cooling channel (HCC) has been proposed to quickly reduce the six-dimensional phase space of muon beams for muon colliders, neutrino factories, and intense muon sources. The HCC is composed of a series of RF cavities filled with dense hydrogen gas that acts as the energy absorber for ionization cooling and suppresses RF breakdown in the cavities. Magnetic solenoidal, helical dipole, and helical quadrupole coils outside of the RF cavities provide the focusing and dispersion needed for the emittance exchange for the beam as it follows a helical equilibrium orbit down the HCC. In the work presented here, two Monte Carlo programs have been developed to simulate a HCC to compare with the analytic predictions and to begin the process of optimizing practical designs that could be built in the near future. We discuss the programs, the comparisons with the analytical theory, and the prospects for a HCC design with the capability to reduce the six-dimensional phase space emittance of a muon beam by a factor of over five orders of magnitude in a linear channel less than 100 meters long.

  15. Convergent ablation measurements with gas-filled rugby hohlraum on OMEGA

    NASA Astrophysics Data System (ADS)

    Casner, A.; Jalinaud, T.; Galmiche, D.

    2016-03-01

    Convergent ablation experiments with gas-filled rugby hohlraum were performed for the first time on the OMEGA laser facility. A time resolved 1D streaked radiography of capsule implosion is acquired in the direction perpendicular to hohlraum axis, whereas a 2D gated radiography is acquired at the same time along the hohlraum axis on a x-ray framing camera. The implosion trajectory has been measured for various kinds of uniformly doped ablators, including germanium-doped and silicon-doped polymers (CH), at two different doping fraction (2% and 4% at.). Our experiments aimed also at measuring the implosion performance of laminated capsules. A laminated ablator is constituted by thin alternate layers of un-doped and doped CH. It has been previously shown in planar geometry that laminated ablators could mitigate Rayleigh Taylor growth at ablation front. Our results confirm that the implosion of a capsule constituted with a uniform or laminated ablator behaves similarly, in accordance with post-shot simulations performed with the CEA hydrocode FCI2.

  16. Plasma Studies in a High Pressure Gas Filled Radio Frequency Cavity

    NASA Astrophysics Data System (ADS)

    Freemire, Ben; Chung, Moses; Tollestrup, Alvin; Yonehara, Katsuya

    2014-10-01

    A Muon Collider offers a great deal of physics potential to the high energy physics community. In order to build such a machine with the desired luminosity, significant cooling of the muon beam is required. One proposed method for doing so is the Helical Cooling Channel, which consists of high pressure gas filled radio frequency (HPRF) cavities arranged in a helix within a strong external magnetic field. To validate this technology, an HPRF cavity was subjected to a 400 MeV proton beam at Fermilab's MuCool Test Area. Parent gases of hydrogen, deuterium, helium and nitrogen, at room temperature and densities up to 2.5E21 cm-3 were used, and doped with sulfur hexafluoride or dry air. The plasma density created by the beam approached 1E16 cm-3. Measurements of the RF energy dissipated per charged particle pair, the electron-ion recombination rate, the ion-ion recombination rate, and electron attachment time were made.

  17. 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. PMID:23481974

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

    SciTech Connect

    Barboza, N.O.

    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 {approximately}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, {approximately}200 g/cm{sup 3} and {approximately}20 keV, that a substantial number of fusion reactions occur; the pellet microexplosion typically releases {approximately}350 MJ of energy in optimized power plant scenarios.

  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. The Evolution of the Gold Bubble in NIF Ignition Gas-Filled Hohlraums

    NASA Astrophysics Data System (ADS)

    Schneider, Marilyn; MacLaren, Steve; Widmann, Klaus; Meezan, Nathan; Hammer, James; Bell, Perry; Benedetti, Robin; Bradley, David; Callahan, Deborah; Dewald, Eduard; Doeppner, Tilo; Hinkel, Denise; Jones, Oggie; Landen, O. L.; Michel, Pierre; Milovich, Jose; Moody, John; Moore, Alastair

    2015-11-01

    At the National Ignition Facility (NIF), the energy from 192 laser beams is converted to an x-ray drive in a gas-filled gold hohlraum. The x-ray drive heats and implodes a fuel capsule. The ViewFactor platform uses a truncated hohlraum to measure the x-ray drive from the capsule point-of-view. This platform also affords excellent diagnostic views of the hohlraum interior, in particular, of the region in which the outer beams deposit their energy (the ``gold bubble'') Time-resolved and time-integrated images in the hard x-ray range (>3 keV) reveal an 8-fold symmetry in the gold bubble. The Au plasma in the bubble from the eight 50 degree quads expands faster than that from the interleaved 44.5 degree quads. The variation in this structure with laser intensity, with pulse shape and cross beam energy transfer, and comparison to models, will be discussed. This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  1. Photoionization of the neon–rare gas dimers NeAr, NeKr, and NeXe

    SciTech Connect

    Pratt, Stephen T.; Dehmer, Patricia M.

    1982-01-01

    The relative photoionization cross sections for the heteronuclear neon--rare gas dimers NeAr, NeKr, and NeXe were measured at a wavelength resolution of 0.15 Â for NeAr and 0.28 Â for NeKr and NeXe in the energy region between the molecular ionization threshold and the atomic ²P⁰1/2 ionization limit of the heavier rare gas atom. The dimer ionization potentials are 15.685±0.004 eV for NeAr, 13.950±0.003 eV for NeKr, and 12.094±0.004 eV for NeXe. Combining these values with the known values of the atomic ionization potentials and the neutral ground state dissociation energies yields values of the A ²Σ⁺1/2 ionic ground state dissociation energies of 0.079±0.004 eV for NeAr, 0.055±0.003 eV for NeKr, and 0.041±0.004 eV for NeXe. Molecular Rydberg structure, which shows strong similarities to the atomic structure in the region of the autoionizing Beutler--Fano resonances, has been partially analyzed in terms of Rydberg series converging to the B ²Π1/2 state of the dimer ion. Vertical binding energies for the individual Rydberg states were determined based on the assumption that the Rydberg states dissociate to a neon atom in the ¹S0 ground state plus a rare gas atom in an ns'[1/2]⁰1 or nd'[3/2]⁰1 excited state. Values of the vertical binding energies of the B ²Π1/2 ionic state were determined from the series limits and are 0.022±0.002 eV for NeAr, 0.018±0.004 eV for NeKr, and 0.014±0.002 eV for NeXe.

  2. Evolution of a gas bubble in porous matrix filled by methane hydrate

    NASA Astrophysics Data System (ADS)

    Tsiberkin, Kirill; Lyubimov, Dmitry; Lyubimova, Tatyana; Zikanov, Oleg

    2013-04-01

    Behavior of a small isolated hydrate-free inclusion (a bubble) within hydrate-bearing porous matrix is studied analytically and numerically. An infinite porous matrix of uniform properties with pores filled by methane hydrates and either water (excessive water situation) or methane gas (excessive gas situation) is considered. A small spherical hydrate-free bubble of radius R0 exists at initial moment within the matrix due to overheating relative to the surrounding medium. There is no continuing heat supply within the bubble, so new hydrate forms on its boundary, and its radius decreases with time. The process is analysed in the framework of the model that takes into account the phase transition and accompanying heat and mass transport processes and assumes spherical symmetry. It is shown that in the case of small (~ 10-2-10-1 m) bubbles, convective fluxes are negligible and the process is fully described by heat conduction and phase change equations. A spherically symmetric Stefan problem for purely conduction-controlled evolution is solved analytically for the case of equilibrium initial temperature and pressure within the bubble. The self-similar solution is verified, with good results, in numerical simulations based on the full filtration and heat transfer model and using the isotherm migration method. Numerical simulations are also conducted for a wide range of cases not amenable to analytical solution. It is found that, except for initial development of an overheated bubble, its radius evolves with time following the self-similar formula: R(t) ( t)1-2 R0-= 1 - tm- , (1) where tm is the life-time of bubble (time of its complete freezing). The analytical solution shows that tm follows 2 tm ~ (R0-?) , (2) where ? is a constant determined by the temperature difference ΔT between the bubble's interior and far field. We consider implications for natural hydrate deposits. As an example, for a bubble with R0 = 4 cm and ΔT = 0.001 K, we find tm ~ 5.7 ? 106 s (2

  3. 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.

  4. Densities and filling factors of the diffuse ionized gas in the Solar neighbourhood

    NASA Astrophysics Data System (ADS)

    Berkhuijsen, E. M.; Müller, P.

    2008-10-01

    Aims: We analyse electron densities and filling factors of the diffuse ionized gas (DIG) in the Solar neighbourhood. Methods: We have combined dispersion measures and emission measures towards 38 pulsars at distances known to better than 50%, from which we derived the mean density in clouds, N_c, and their volume filling factor, F_v, averaged along the line of sight. The emission measures were corrected for absorption by dust and contributions from beyond the pulsar distance. Results: The scale height of the electron layer for our sample is 0.93± 0.13 kpc and the midplane electron density is 0.023± 0.004 cm-3, in agreement with earlier results. The average density along the line of sight is < n_e> = 0.018± 0.002 cm-3 and is nearly constant. Since < n_e> = F_vN_c, an inverse relationship between Fv and Nc is expected. We find F_v(N_c) = (0.011± 0.003) N_c-1.20± 0.13, which holds for the ranges N_c= 0.05-1 cm-3 and F_v= 0.4-0.01. Near the Galactic plane the dependence of Fv on Nc is significantly stronger than away from the plane. Fv does not systematically change along or perpendicular to the Galactic plane, but the spread about the mean value of 0.08± 0.02 is considerable. The total pathlength through the ionized regions increases linearly to about 80 pc towards |z| = 1 kpc. Conclusions: Our study of Fv and Nc of the DIG is the first one based on a sample of pulsars with known distances. We confirm the existence of a tight, nearly inverse correlation between Fv and Nc in the DIG. The exact form of this relation depends on the regions in the Galaxy probed by the pulsar sample. The inverse F_v-Nc relation is consistent with a hierarchical, fractal density distribution in the DIG caused by turbulence. The observed near constancy of < n_e> then is a signature of fractal structure in the ionized medium, which is most pronounced outside the thin disk.

  5. 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...

  6. 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.

  7. 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.

  8. Domain control of ZnO nanoparticles in a coaxial gas-flow pulse Ar/O2 plasma

    NASA Astrophysics Data System (ADS)

    Iizuka, Satoru; Shirahata, Hiroki

    2015-09-01

    A limited area, to which ZnO nanoparticles are selectively adhered, is called a domain. Formation of the domain was controlled by using a coaxial gas-flow pulse Ar/O2 plasma. It was found that the mechanism of domain formation was closely related to the initial surface condition of Si substrate. Especially, the cleaning process was crucial. Here, we employed a patterning of the domain by using a fine mesh as a template. The formation processes were estimated by SEM and EDX. The technique developed here will be applied to a selective nanoparticle patterning.

  9. Noble gas-sulfur anions: A theoretical investigation of FNgS - (Ng = He, Ar, Kr, Xe)

    NASA Astrophysics Data System (ADS)

    Borocci, Stefano; Bronzolino, Nicoletta; Grandinetti, Felice

    2008-06-01

    MP2, coupled-cluster, and multireference-CI calculations were performed to investigate the structure, stability, and properties of the noble gas anions FNgS- (Ng = He, Ar, Kr, Xe). Similar to the recently investigated FNgO- and FNgBN-, these species reside into deep wells on the singlet surface, protected by sizable barriers with respect to FS- + Ng and F- + Ng + S(3P). Their stability arises from the strong F--stabilization of the elusive NgS. The lightest FHeS- and FArS- are also first predicted examples of helium-sulfur and argon-sulfur molecular species.

  10. Electrical system for measurement of breakdown voltage of vacuum and gas-filled tubes using a dynamic method

    NASA Astrophysics Data System (ADS)

    Pejović, Milić M.; Milosavljević, Čedomir S.; Pejović, Momčilo M.

    2003-06-01

    This article describes an electrical system aimed at measuring and data acquisition of breakdown voltages of vacuum and gas-filled tubes. The measurements were performed using a nitrogen-filled tube at 4 mbar pressure. Based on the measured breakdown voltage data as a function of the applied voltage increase rate, a static breakdown voltage is estimated for the applied voltage gradient ranging from 0.1 to 1 V s-1 and from 1 to 10 V s-1. The histograms of breakdown voltages versus applied voltage increase rates from 0.1 and 0.5 V s-1 are approximated by the probability density functions using a fitting procedure.

  11. Fabrication of cm scale buckypapers of horizontally aligned multiwalled carbon nanotubes highly filled with Fe3C: the key roles of Cl and Ar-flow rates.

    PubMed

    Boi, Filippo S; Guo, Jian; Wang, Shanling; He, Yi; Xiang, Gang; Zhang, Xi; Baxendale, Mark

    2016-03-18

    A key challenge in the fabrication of ferromagnetically filled carbon-nanotube buckypapers in the presence of Cl-radicals is the achievement of a preferential horizontal nanotube-alignment. We show that a horizontal-alignment can be achieved by tuning two main CVD parameters for a fixed dichlorobenzene concentration: the precursor-evaporation temperature and the flow rate. PMID:26905009

  12. Four-phase fully-coupled mold-filling and solidification simulation for gas porosity prediction in aluminum sand casting

    NASA Astrophysics Data System (ADS)

    Jakumeit, J.; Jana, S.; Waclawczyk, T.; Mehdizadeh, A.; Sadiki, A.; Jouani, J.

    2012-07-01

    The impact of mold-filling and oxide film enclosure on gas porosity in A356 was investigated using a three-phase, fully-coupled, mold-filling and solidification simulation. For the prediction of gas porosity, a fourth hydrogen phase was added. At the solidification front hydrogen is rejected from the solid and accumulates in the melt. Pores nucleate if the solute gas exceeds the solubility limit. Air and melt are separated by a volume of fluid interface and special treatment of the hydrogen phase convection was necessary to limit the hydrogen to the melt. Folding of the melt surface was used as a source for oxide film entrainment. These oxide films were transported with the melt and used as nucleation sites for gas porosity formation. The influence of melt flow due to filling and oxide film distribution was analyzed using a simple 3-block test geometry. The test geometry was cast in A356 and analyzed by computer tomography to validate the porosity prediction.

  13. 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.

  14. Theory of photoionization-induced blueshift of ultrashort solitons in gas-filled hollow-core photonic crystal fibers.

    PubMed

    Saleh, Mohammed F; Chang, Wonkeun; Hölzer, Philipp; Nazarkin, Alexander; Travers, John C; Joly, Nicolas Y; Russell, Philip St J; Biancalana, Fabio

    2011-11-11

    We show theoretically that the photoionization process in a hollow-core photonic crystal fiber filled with a Raman-inactive noble gas leads to a constant acceleration of solitons in the time domain with a continuous shift to higher frequencies, limited only by ionization loss. This phenomenon is opposite to the well-known Raman self-frequency redshift of solitons in solid-core glass fibers. We also predict the existence of unconventional long-range nonlocal soliton interactions leading to spectral and temporal soliton clustering. Furthermore, if the core is filled with a Raman-active molecular gas, spectral transformations between redshifted, blueshifted, and stabilized solitons can take place in the same fiber. PMID:22181733

  15. 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...

  16. Combined soliton pulse compression and plasma-related frequency upconversion in gas-filled photonic crystal fiber.

    PubMed

    Chang, W; Hölzer, P; Travers, J C; Russell, P St J

    2013-08-15

    We numerically investigate self-frequency blueshifting of a fundamental soliton in a gas-filled hollow-core photonic crystal fiber. Because of the changing underlying soliton parameters, the blueshift gives rise to adiabatic soliton compression. Based on these features, we propose a device that enables frequency shifting over an octave and pulse compression from 30 fs down to 2.3 fs. PMID:24104627

  17. 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).

  18. Observation of reduced beam deflection using smoothed beams in gas-filled hohlraum symmetry experiments at Nova

    SciTech Connect

    Delamater, N. D.; Lindman, E. L.; Magelssen, G. R.; Failor, B. H.; Murphy, T. J.; Hauer, A. A.; Gobby, P.; Moore, J. B.; Gomez, V.; Gifford, K.

    2000-05-01

    Execution and modeling of drive symmetry experiments in gas-filled hohlraums have been pursued to provide both a better understanding of radiation symmetry in such hohlraums and to verify the accuracy of the design tools which are used to predict target performance for the National Ignition Facility (NIF) [J. Lindl, Phys. Plasmas 2, 3933 (1995)]. In this paper, the results of a series of drive symmetry experiments using gas-filled hohlraums at the Nova laser facility [C. Bibeau et al., Appl. Opt. 31, 5799 (1992)] at Lawrence Livermore National Laboratory are presented. A very important element of these experiments was the use of kineform phase plates (KPP) to smooth the Nova beams. The effect of smoothing the ten Nova beams with KPP phase plates is to remove most of the beam bending which had been observed previously, leaving a residual bending of only 1.5 degree sign , equivalent to a 35 {mu}m pointing offset at the hohlraum wall. The results show that the symmetry variation with pointing of implosions in gas-filled hohlraums is consistent with time integrated modeling. (c) 2000 American Institute of Physics.

  19. Modeling of the atomic Ne laser in He/Ne/Ar gas mixtures

    SciTech Connect

    Jong, W.; Kushner, S.; Kushner, M.J.

    1992-12-01

    The high pressure atomic Ne laser operates on 4 visible transitions between the 3p and 3s manifolds. There has been renewed interest in this laser due to demonstrated high efficiency lasing at 585 nm in e-beam and fission fragment excited plasmas. A comprehensive computer model for the Ne laser in He/Ne/Ar mixtures has been developed to examine excitation mechanisms. The authors found that direct excitation of the 3p manifold by dissociative recombination of Ne{sub 2}{sup +} is the likely pumping mechanism, while state-selective Penning reactions dominantly relax the lower levels. Comparisons to experiments performed on a short pulsed e-beam excited laser showed that the electron temperature in the afterglow is determined by a slow relaxation of excited states in Ar. Oscillation does not occur until these manifolds are depleted, and the electron temperature falls. Scaling laws for the Ne laser at low pump powers, as obtained using fission fragment excitation, will be discussed.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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. PMID:25503011

  5. 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%.

  6. Geomicrobiology and occluded O 2-CO 2-Ar gas analyses provide evidence of microbial respiration in ancient terrestrial ground ice

    NASA Astrophysics Data System (ADS)

    Lacelle, Denis; Radtke, Kristin; Clark, Ian D.; Fisher, David; Lauriol, Bernard; Utting, Nicholas; Whyte, Lyle G.

    2011-06-01

    The study of ancient massive ground ice and sediment-rich ice bodies not only allows an understanding of the stability of permafrost, but also offers the possibility to understand the long-term preservation and viability of microbes within these ice bodies. Although microorganisms have been identified in ancient bodies of ground ice and permafrost, there still is a lack of convincing evidence that the microbes were metabolically active within the ice. In this study, we combine geomicrobiology methods with the measurements of occluded gasses in four ancient massive ground ice bodies to provide evidence of microbial respiration. In our samples, abundant cold-adapted heterotroph microorganisms were identified using culture-dependent and -independent methods. The occluded gas measurements, with low δ(O 2/Ar) (less than - 21.4%) and δ 13C CO 2 (as low as - 25.2‰) values and high δ 18O O 2 (up to + 16.3‰) values are suggestive of in situ consumption of O 2 by heterotrophic psychrophilic bacteria living within the ice matrix. Overall, the multi-disciplinary approach provides a strong set of tools from which to infer metabolic activity within bodies of ground ice. The analysis of δ(O 2/Ar), δ 18O O 2 and δ 13C CO 2 from occluded gasses in ice are strong isotope biosignatures that could allow detecting evidence of life on other planetary icy bodies such as Mars.

  7. 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.

  8. Exploration of kinetic and multiple-ion-fluids effects in D3He and T3He gas-filled ICF implosions using multiple nuclear reaction histories

    NASA Astrophysics Data System (ADS)

    Sio, Hong; Rinderknecht, Hans; Rosenberg, Michael; Zylstra, Alex; Séguin, Fredrick; Gatu Johnson, Maria; Li, Chikang; Petrasso, Richard; Hoffman, Nelson; Kagan, Krigory; Molvig, Kim; Amendt, Peter; Bellei, Claudio; Wilks, Scott; Stoeckl, Christian; Glebov, Vladimir; Betti, Riccardo; Sangster, Thomas; Katz, Joseph

    2014-10-01

    To explore kinetic and multi-ion-fluid effects in D3He and T3He gas-filled shock-driven implosions, multiple nuclear reaction histories were measured using the upgraded Particle Temporal Diagnostic (PTD) on OMEGA. For D3He gas-filled implosions, the relative timing of the DD and D3He reaction histories were measured with 20 ps precision. For T3He gas-filled implosions (with 1-2% deuterium), the relative timing of the DT and D3He reaction histories were measured with 10 ps precision. The observed differences between the reaction histories on these two OMEGA experiments are contrasted to 1-D single-ion hydro simulations for different gas-fill pressure and gas mixture. This work is supported in part by the U.S. DOE, LLNL, LLE, and NNSA SSGF.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  10. 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.

  11. 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).

  12. Uranium dioxide films with xenon filled bubbles for fission gas behavior studies

    NASA Astrophysics Data System (ADS)

    Usov, I. O.; Dickerson, R. M.; Dickerson, P. O.; Byler, D. D.; McClellan, K. J.

    2014-09-01

    Electron beam evaporation and ion beam assisted deposition (IBAD) methods were utilized to fabricate depleted UO2 films and UO2 films with embedded Xe atoms, respectively. The films were fabricated at elevated temperature of 700 °C and also subsequently annealed at 1000 °C to induce grain growth and Xe atom redistribution. The goal of this work was to synthesize reference UO2 samples with controlled microstructures and Xe-filled bubble morphologies, without the effects attendant to rector irradiation-induced fission. Transmission electron microscopy (TEM) microstructural characterization revealed that fine Xe-filled bubbles nucleated in the as grown films and subsequent annealing resulted in noticeable bubble size increase. Reported results demonstrate the great potential IBAD techniques and UO2 films have for various areas of nuclear materials studies.

  13. Ar-40/Ar-39 ages of Meishan Bed 25 sanidine and igneous intrusions from the Siberian platform compared: implications for the timing of gas emissions and the End-Permian extinction

    NASA Astrophysics Data System (ADS)

    Storey, M.; Reichow, M. K.; Saunders, A. D.

    2013-12-01

    The end-Permian mass extinction wiped out nearly all life on our planet. The cause for this cataclysmic event and whether this appeared as a double extinction is a matter of current debate. The most favoured candidate is volatile release from either magmatic degassing directly or induced by interaction between magmas and volatile bearing deposits. Release of volatiles during thermal metamorphism and assimilation of coal and evaporite deposits which are widespread on the Siberian platform following igneous intrusion has been proposed as a major cause of the environmental and extinction event at the end of the Permian, with venting of carbon gases and halocarbons to the atmosphere leading to global warming and atmospheric ozone depletion (Svensen et al., 2009). To meaningfully examine this proposed causality requires precise dating of the Siberian intrusions at the ';Earthtime' goal of × 0.1 % or better. Here we present preliminary results from Ar-40/Ar-39 step heating experiments on plagioclase and biotite from Siberian basin intrusions and compare the data with published and new Ar-40/Ar-39 sanidine ages for Bed 25 from the global section and Permian-Triassic boundary stratotype at Meishan, China. REFERENCES H. Svensen et al., Siberian gas venting and the end-Permian environmental crisis, Earth and Planetary Science Letters, volume 277, 490-500, 200

  14. Effect of Cl{sub 2}/Ar gas mixing ratio on (Pb,Sr)TiO{sub 3} thin film etching behavior in inductively coupled plasma

    SciTech Connect

    Kim, Gwan-Ha; Kim, Chang-Il

    2006-07-15

    The development of anisotropic etching process for (Pb,Sr)TiO{sub 3} (PST) thin films is an important task to provide a small feature size and an accurate pattern transfer. Etching characteristics of PST thin films were investigated using inductively coupled plasma etching system as functions of Cl{sub 2}/Ar gas mixing ratio. The PST etch rate increased with the increase of chlorine radical and ion energy intensity. It was found that the increasing of Ar content in gas mixture lead to sufficient increasing of etch rate. The maximum etch rate of PST film is 56.2 nm/min at Cl{sub 2}/(Cl{sub 2}+Ar) of 0.2. It was proposed that the sputter etching is a dominant etching mechanism while the contribution of chemical reaction is relatively low due to low volatility of etching products.

  15. 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.

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

    PubMed

    Rakowski, R; Barna, A; Suta, T; Bohus, J; Földes, I B; Szatmári, S; Mikołajczyk, J; Bartnik, A; Fiedorowicz, H; Verona, C; Verona Rinati, G; Margarone, D; Nowak, T; Rosiński, M; Ryć, L

    2014-12-01

    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. PMID:25554270

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  18. Wall thickness of gas- and marrow-filled avian long bones: measurements on humeri, femora and tibiotarsi in crows (Corvus corone cornix) and magpies (Pica pica).

    PubMed

    Suhai, Bence; Gasparik, Mihály; Csorba, Gábor; Gerics, Balázs; Horváth, Gábor

    2006-01-01

    We studied how the ratio K of the internal to external diameter of gas- and marrow-filled avian long bones follows the biomechanical optima derived for tubular bones with minimum mass designed to fulfil various mechanical requirements. We evaluated radiographs of numerous humeri, femora and tibiotarsi in Corvus corone cornix and Pica pica. The K-values of the gas-filled humerus (K=0.78+/-0.03) and the marrow-filled femur (K=0.79+/-0.02) in Corvus are practically the same, while K of the marrow-filled tibiotarsus (K=0.71+/-0.04) is significantly smaller. The same is true for the gas-filled humerus (K=0.78+/-0.02) and the marrow-filled femur (K=0.77+/-0.02) and tibiotarsus (K=0.67+/-0.05) in Pica. K in Corvus is slightly larger than K in Pica, but the differences are statistically not significant. The standard deviation DeltaK of the tibiotarsi (DeltaK=0.04-0.05) is approximately two times as large as that of the humeri (DeltaK=0.02-0.03) and femora (DeltaK=0.02) in both species. Accepting the assumption of earlier authors that the ratio Q of the marrow to bone density is 0.5, our data show that the marrow-filled tibiotarsi of Corvus and Pica are optimized for stiffness, while the marrow-filled femora are far from any optimum. The relative wall thickness W=1-K of the gas-filled avian humeri studied is much larger than the theoretical optimum W*=1-K*=0.07, and thus these bones are thicker-walled than the optimal gas-filled tubular bone with minimum mass. PMID:16084519

  19. Amplitude blanking related to the pore-filling of gas hydrate in sediments

    USGS Publications Warehouse

    Lee, M.W.; Dillon, William P.

    2001-01-01

    Seismic indicators of gas-hydrate-bearing sediments include elevated interval velocities and amplitude reduction of seismic reflections owing to the presence of gas hydrate in the sediment's pore spaces. However, large amplitude blanking with relatively low interval velocities observed at the Blake Ridge has been enigmatic because realistic seismic models were absent to explain the observation. This study proposes models in which the gas hydrate concentrations vary in proportion to the porosity. Where gas hydrate concentrations are greater in more porous media, a significant amplitude blanking can be achieved with relatively low interval velocity. Depending on the amount of gas hydrate concentration in the pore space, reflection amplitudes from hydrate-bearing sediments can be much less, less or greater than those from corresponding non-hydrate-bearing sediments.

  20. The Lampedusa supersite of ChArMex: observing aerosol-radiation interactions and gas phase chemistry in the Mediterranean

    NASA Astrophysics Data System (ADS)

    Formenti, Paola; di Sarra, Alcide Giorgio

    2014-05-01

    Within the frame of the ADRIMED (Aerosol Direct Radiative Impact in the regional climate in the MEDiterranean region) project of the Chemistry-Aerosol Mediterranean experiment (ChArMex), the ENEA Laboratory for Climate Study "Roberto Sarao" (WMO/GAW/NDACC) on the Island of Lampedusa (35°31'N, 12°37°E) has been augmented to one of the supersites of the first phase of the Special Observing Period 1 by the measurements of the in situ properties of aerosols and trace gases by the of the PortablE Gas and Aerosol Sampling Units (PEGASUS) mobile station. The ground-based measurements have been completed by several coordinated overpasses of the ATR-42 and the F20 of SAFIRE. In this paper we present the first highlights of operations, which took place between June 6 and July 8 2013. Insights on the data provide with an unprecedented characterisation of the physico-chemical and properties aerosols and gas phase chemistry on air masses of various origins (pollution, marine, mineral dust, …..). The effect of aerosols on radiation fields is ascertained by coupling ground-based and aircraft measurements during dedicated overpasses providing with measurements of upwelling and downwelling shortwave and longwave radiation fluxes together with the properties of the aerosol load resolved on the column. Coordination with CALIPSO overpasses will also be explored.

  1. Investigations of x-ray response of single wire anode Ar-N 2 flow type gas scintillation proportional counters

    NASA Astrophysics Data System (ADS)

    Garg, S. P.; Sharma, R. C.

    1984-05-01

    The X-ray response of single wire anode gas scintillation proportional counters of two different geometries operated with argon + nitrogen gases in continuous flow has been investigated with wire anodes of diameters 25 μm to 1.7 mm. An energy resolution of 19% is obtained for 5.9 keV X-rays entering the counter perpendicular to the anode in pill-box geometry with 25 μm diameter anode. With cylindrical geometry counters energy resolutions obtained at 5.9 keV are 18%, 24% and 33% for 50 μm, 0.5 mm and 1.7 mm diameter anodes respectively. An analysis of the observed resolution shows that the contribution from photon counting statistics to the relative variance of scintillation pulses even for X-rays in Ar-N 2 single wire anode gas scintillation proportional counters is small and is not a limiting factor. The energy resolution with thicker anodes, where the contribution from the variance of the charge multiplication factor also has been minimised, is found to deteriorate mainly by the interactions in the scintillation production region. Comments are made on the possibility of improvement in energy resolution by suppression of pulses due to such interactions with the help of the pulse risetime discrimination technique.

  2. An overview of noble gas (He, Ne, Ar, Xe) contents and isotope signals in terrestrial diamond

    NASA Astrophysics Data System (ADS)

    Basu, S.; Jones, A. P.; Verchovsky, A. B.; Kelley, S. P.; Stuart, F. M.

    2013-11-01

    The noble gas geochemistry of different types of terrestrial diamond including coated stones, alluvial diamonds, framesites, carbonados and impact diamonds yields a wealth of information on the sources of volatiles responsible for diamond formation. We present an illustrated compilation of published analyses of noble gases in different types of natural diamond. Noble gases in diamond record primary signatures from the mantle indicative of their integrated sources, and, the contribution of different metasomatic agents including subducting fluids and kimberlitic melt sampled during diamond growth. In addition, they show evidence of secondary processes such as resorption. Most data are available for coated stones, which trap abundant volatile-rich microscopic inclusions in their rims. While the coated stones are dominated by Mid-Oceanic-Ridge-Basalt (MORB) type noble gas signatures, the other diamond types contain predominantly crustal and atmospheric components although some mantle gases may be present, the latter indicated in elevated 20Ne/22Ne and/or 129Xe/132Xe ratios relative to atmospheric values. Some alluvial diamonds have very high 3He/4He that may represent the presence of a solar component trapped during their formation, but are just as likely to be the result of cosmogenic 3He implantation during their prolonged residence at the Earth's surface. Oceanic-Island-Basalt (OIB) type noble gases occur in nanometer sized inclusions in metamorphic diamond from Kazakhstan, yet their significance as a fingerprint of mantle processes is not fully understood. Implanted noble gases occur near the outer surfaces of individual crystals, and are generally not a major hindrance for the study of mantle signatures, except for polycrystalline diamond like framesites with small grain size. Some diamonds including the polycrystalline carbonados, are dominated by crustal noble gases with no discernible mantle component evidenced by very low 3He/4He and 20Ne/22Ne ratios, and very

  3. 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.

  4. Simulation of oscillatory processes in a beam-plasma system with a virtual cathode in gas-filled interaction space

    SciTech Connect

    Filatov, R. A.; Hramov, A. E.

    2011-05-15

    Physical processes occurring in an intense electron beam with a virtual cathode in an interaction space filled with neutral gas are studied in a two-dimensional model. A mathematical model is proposed for investigating complicated self-consistent processes of neutral gas ionization by the beam electrons and the dynamics of an electron beam and heavy positive ions in the common space charge field with allowance for the two-dimensional motion of charged particles. Three characteristic dynamic regimes of the system are revealed: complete suppression of oscillations of the virtual cathode as a result of neutralizing its space charge by positive ions; the pulsed generation regime, in which the ions dynamics repeatedly suppresses and restores the virtual cathode oscillations; and the continuous generation regime with an anomalously high level of noisy oscillations.

  5. 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.; Klem, D.E.; Montgomery, D.S.; Moody, J.D.; Munro, D.H.; Stone, G.F. ); Hsing, W.W. ); Failor, B.H. )

    1995-01-01

    We report on the production and characterization of large scale-length plasmas created by illuminating gas-filled thin-walled balloonlike targets using the Nova laser. The targets consisted of a 5--6000 A 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 gas bag. An alternate focus geometry using small beam spots resulted in a less uniform plasma with low density holes in it.

  6. Tunable vacuum-UV to visible ultrafast pulse source based on gas-filled Kagome-PCF.

    PubMed

    Mak, Ka Fai; Travers, John C; Hölzer, Philipp; Joly, Nicolas Y; Russell, Philip St J

    2013-05-01

    An efficient and tunable 176-550 nm source based on the emission of resonant dispersive radiation from ultrafast solitons at 800 nm is demonstrated in a gas-filled hollow-core photonic crystal fiber (PCF). By careful optimization and appropriate choice of gas, informed by detailed numerical simulations, we show that bright, high quality, localized bands of UV light (relative widths of a few percent) can be generated at all wavelengths across this range. Pulse energies of more than 75 nJ in the deep-UV, with relative bandwidths of ~3%, are generated from pump pulses of a few μJ. Excellent agreement is obtained between numerical and experimental results. The effects of positive and negative axial pressure gradients are also experimentally studied, and the coherence of the deep-UV dispersive wave radiation numerically investigated. PMID:23669950

  7. Subwatt threshold cw Raman fiber-gas laser based on H2-filled hollow-core photonic crystal fiber.

    PubMed

    Couny, F; Benabid, F; Light, P S

    2007-10-01

    We report on what is, to our knowledge, the first cw pumped Raman fiber-gas laser based on a hollow-core photonic crystal fiber filled with hydrogen. The high efficiency of the gas-laser interaction inside the fiber allows operation in a single-pass configuration. The transmitted spectrum exhibits 99.99% of the output light at the Stokes wavelength and a pump power threshold as low as 2.25 W. The study of the Stokes emission evolution with pressure shows that highly efficient Raman amplification is still possible even at atmospheric pressure. The addition of fiber Bragg gratings to the system, creating a cavity at the Stokes wavelength, reduces the Raman threshold power below 600 mW. PMID:17930673

  8. Strong Raman-induced noninstantaneous soliton interactions in gas-filled photonic crystal fibers.

    PubMed

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

    2015-09-01

    We have developed an analytical model based on the perturbation theory to study the optical propagation of two successive solitons in hollow-core photonic crystal fibers filled with Raman-active gases. Based on the time delay between the two solitons, we have found that the trailing soliton dynamics can experience unusual nonlinear phenomena, such as spectral and temporal soliton oscillations and transport toward the leading soliton. The overall dynamics can lead to a spatiotemporal modulation of the refractive index with a uniform temporal period and a uniform or chirped spatial period. PMID:26368711

  9. Optical design and characterization of a gas filled MEMS Fabry-Perot filter

    NASA Astrophysics Data System (ADS)

    Ayerden, N. Pelin; Ghaderi, Mohammadamir; de Graaf, Ger; Wolffenbuttel, Reinoud F.

    2015-05-01

    A concept for a highly integrated and miniaturized gas sensor based on infrared absorption, a Fabry-Perot type linear variable optical filter with integrated gas cell, is presented. The sample chamber takes up most of the space in a conventional spectrometer and is the only component that has so far not been miniaturized. In this concept the gas cell is combined with the resonator cavity of the filter. The optical design, fabrication, and characterization results on a MEMSbased realization are reported for a 24-25.5 μm long tapered resonator cavity. Multiple reflections from highly reflective mirrors enable this optical cavity to also act as a gas cell with an equivalent optical absorption path length of 8 mm. Wideband operation of the filter is ensured by fabrication of a tapered mirror. In addition to the functional integration and significant size reduction, the filter contains no moving parts, thus enables the fabrication of a robust microspectrometer

  10. 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.

  11. 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.

  12. 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.

  13. Effective medium modeling of gas hydrate-filled fractures using the sonic log in the Krishna-Godavari basin, offshore eastern India

    NASA Astrophysics Data System (ADS)

    Ghosh, Ranjana; Sain, Kalachand; Ojha, Maheswar

    2010-06-01

    Indian National Gas Hydrate Program Expedition 01 has established that clay-rich marine sediment from the Krishna-Godavari (KG) basin in the eastern Indian margin hosts one of the richest gas hydrate deposits in the world. Resistivity at-bit images and pressure cores reveal that the gas hydrate morphology in clay-rich sediment varies from complex vein structures (grain displacing) to invisible pore filling. Existing rock physics models, which relate acoustic data to in situ gas hydrate concentrations, generally assume isotropic pore-filling gas hydrate, which yields misleading concentration estimates for fractured fine-grained sediments. The anisotropic KG basin sediment presents additional complications. Here we apply differential effective medium theory to incorporate grain-displacing morphologies by which gas hydrate is included as vertical ellipsoids with aspect ratios ranging from those of thin veins up to those of nodules in an elastic anisotropic background. We have estimated gas hydrate concentrations from sonic velocities at hole 10D in the KG basin considering three basic gas hydrate morphologies: (i) pore filling, (ii) grain displacing, and (iii) a combination of grain displacing and pore filling. Average gas hydrate saturations for these three cases are 35-42%, 27-30%, and 33-41% of the total porosity, respectively, in the depth range 60-140 m below seafloor (mbsf). Saturation is highest at ˜67 mbsf for any morphology but the values differ between morphologies. For the pore-filling morphology, the maximum gas hydrate saturation of 56% is 18-22% higher than the grain-displacing morphology and 2-9% higher than the combined morphology. Estimates differ by ±6% of the sediment volume with rotations of gas hydrate veins from vertical to horizontal.

  14. 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.

  15. Gas amplification factor in Kr + ISO-pentane filled proportional counters

    NASA Astrophysics Data System (ADS)

    Kowalski, T. Z.

    1983-11-01

    The gas amplification factor, A, has been measured for krypton/iso-pentane mixtures (over the range 1 < A < 5 × 104) to verify the validity of the formulae of Rose and Korff, Curran and Craggs, Diethorn, Williams and Sara, Khristov and Zastawny. Only the expressions of Zastawny and Diethorn can be fitted over a limited range of A.

  16. 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., Jr.; 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.

  17. Understanding the amorphous-to-microcrystalline silicon transition in SiF4/H2/Ar gas mixtures

    NASA Astrophysics Data System (ADS)

    Dornstetter, Jean-Christophe; Bruneau, Bastien; Bulkin, Pavel; Johnson, Erik V.; Roca i Cabarrocas, Pere

    2014-06-01

    We report on the growth of microcrystalline silicon films from the dissociation of SiF4/H2/Ar gas mixtures. For this growth chemistry, the formation of HF molecules provides a clear signature of the amorphous to microcrystalline growth transition. Depositing films from silicon tetrafluoride requires the removal of F produced by SiF4 dissociation, and this removal is promoted by the addition of H2 which strongly reacts with F to form HF molecules. At low H2 flow rates, the films grow amorphous as all the available hydrogen is consumed to form HF. Above a critical flow rate, corresponding to the full removal of F, microcrystalline films are produced as there is an excess of atomic hydrogen in the plasma. A simple yet accurate phenomenological model is proposed to explain the SiF4/H2 plasma chemistry in accordance with experimental data. This model provides some rules of thumb to achieve high deposition rates for microcrystalline silicon, namely, that increased RF power must be balanced by an increased H2 flow rate.

  18. Noble-Gas-Inserted Fluoro(sulphido)boron (FNgBS, Ng = Ar, Kr, and Xe): A Theoretical Prediction.

    PubMed

    Ghosh, Ayan; Dey, Sourav; Manna, Debashree; Ghanty, Tapan K

    2015-06-01

    The possibility of the existence of a new series of neutral noble gas compound, FNgBS (where Ng = Ar, Kr, Xe), is explored theoretically through the insertion of a Ng atom into the fluoroborosulfide molecule (FBS). Second-order Møller-Plesset perturbation theory, density functional theory, and coupled cluster theory based methods have been employed to predict the structure, stability, harmonic vibrational frequencies, and charge distribution of FNgBS molecules. Through energetics study, it has been found that the molecules could dissociate into global minima products (Ng + FBS) on the respective singlet potential energy surface via a unimolecular dissociation channel; however, the sufficiently large activation energy barriers provide enough kinetic stability to the predicted molecules, which, in turn, prevent them from dissociating into the global minima products. Moreover, the FNgBS species are thermodynamically stable, owing to very high positive energies with respect to other two two-body dissociation channels, leading to FNg + BS and F(-) + NgBS(+), and two three-body dissociation channels, corresponding to the dissociation into F + Ng + BS and F(-) + Ng + BS(+). Furthermore, the Mulliken and NBO charge analysis together with the AIM results reveal that the Ng-B bond is more of covalent in nature, whereas the F-Ng bond is predominantly ionic in character. Thus, these compounds can be better represented as F(-)[NgBS](+). This fact is also supported by the detail analysis of bond length, bond dissociation energy, and stretching force constant values. All of the calculated results reported in this work clearly indicate that it might be possible to prepare and characterize the FNgBS molecules in cryogenic environment through matrix isolation technique by using a mixture of OCS/BF3 in the presence of large quantity of noble gas under suitable experimental conditions. PMID:25928588

  19. Noble Gas Inserted Protonated Silicon Monoxide Cations: HNgOSi(+) (Ng = He, Ne, Ar, Kr, and Xe).

    PubMed

    Sekhar, Pooja; Ghosh, Ayan; Ghanty, Tapan K

    2015-11-25

    The existence of noble gas containing protonated silicon monoxide complexes have been predicted theoretically through ab initio quantum chemical methods. The predicted HNgOSi(+) ions are obtained by insertion of a noble gas atom (Ng = He, Ne, Ar, Kr, and Xe) between the H and O atoms in SiOH(+) ion. The structural parameters, energetics, harmonic vibrational frequencies, and charge distributions have been analyzed by optimizing the minima and the transition state structures using second-order Møller-Plesset perturbation theory (MP2), density functional theory (DFT), and coupled-cluster theory (CCSD(T)) based techniques. The predicted HNgOSi(+) ions are found to be stable with respect to all possible 2-body and 3-body dissociation channels, except the dissociation path leading to the respective global minimum products. However, these ions are found to be kinetically stable with respect to the global minimum dissociation process as revealed from the finite barrier heights, which in turn can prevent the transformation of these metastable species to the global minimum products. Furthermore, the computed bond lengths, vibrational frequencies, and force constant values suggest that a strong covalent bond exists between the H and Ng atoms in HNgOSi(+) ions while the Ng and O atoms share a strong van der Waals kind of interaction. Charge distributions and bonding analysis indicate that HNgOSi(+) ions can be best represented as strong complexes between the [HNg](+) ions and OSi molecule. All the computational results suggest that the predicted species, HNgOSi(+), may be prepared and characterized by suitable experimental technique at cryogenic temperature. PMID:26501440

  20. Fabrication and testing of gas filled targets for large scale plasma experiments on Nova

    SciTech Connect

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

    1995-03-06

    An experimental campaign on the Nova laser was started in July 1993 to study one st of target conditions for the point design of the National Ignition Facility (NIF). The targets were specified to investigate the current NIF target conditions--a plasma of {approximately}3 keV electron temperature and an electron density of {approximately}1.0 E + 21 cm{sup {minus}3}. A gas cell target design was chosen to confine as gas of {approximately}0.01 cm{sup 3} in volume at {approximately} 1 atmosphere. This paper will describe the major steps and processes necessary in the fabrication, testing and delivery of these targets for shots on the Nova Laser at LLNL.

  1. 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.

  2. 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}.

  3. Plume propagation and Pt film growth during shadow-masked pulsed laser deposition in a buffer Ar gas

    NASA Astrophysics Data System (ADS)

    Fominski, V. Yu.; Grigoriev, S. N.; Gnedovets, A. G.; Romanov, R. I.; Volosova, M. A.

    2015-01-01

    Shadow-masked pulsed laser deposition (SMPLD) enables the preparation of films that contain none of the droplets that are normally formed in laser irradiation of the target. The platinum (Pt) film produced by SMPLD was studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), and Rutherford backscattering spectroscopy (RBS) of helium ions. The film thickness distribution across the substrate surface took the shape of a simple crater, and the film thickness on the crated "bottom" (center of the shadow area) was approximately 5 times less than that on the "mound" (edge of the shadow area). Monte Carlo collision (MCC) modeling of the laser plume movement during SMPLD was performed to clarify the role of the mask in the formation of the Pt films. The dynamics of the Pt atoms in the laser plume was studied using the vacuum deposition method through a narrow slit onto a rapidly displaced substrate, augmented by RBS measurements of the deposited film thickness along the substrate movement direction. The ionic flux was specifically measured using an ion probe. MCC simulation allowed the changes in the basic parameters of the deposited atom stream to be evaluated with the use of a mask. Comparison of the experimental and calculated distribution of the Pt film indicated that the best correlation was observed using the interpenetration model of the plume and buffer gas (argon, Ar) accompanied by elastic collisions of Pt atoms with the Ar atoms using the variable hard sphere model. Atomic flux models were utilized to imitate the growth of individual Pt crystals using the kinetic Monte Carlo method. In the SMPLD case, the root mean square roughness of the model crystal surface increased by ∼10% and the concentration of vacancies increased by ∼4% compared with the model crystal obtained by pulsed laser deposition (PLD). The surface topography of the experimental Pt films was defined by the nanocrystal nature of their structure. The use of a mask

  4. A system for field gas-extraction of 85Kr, 39Ar and 81Kr using SuperPhobic membrane contactors

    NASA Astrophysics Data System (ADS)

    Burk, L.; Suckow, A.; Cook, P.; Mathouchanh, E.

    2013-12-01

    Radioactive noble gas isotopes are established tools for assessing groundwater movement and transport processes on time scales of decades (85Kr), centuries (39Ar) and many millenia (81Kr). While the atomic trap trace analysis (ATTA) technology promises small sample sizes for these isotopes, field gas extraction will remain the method of choice for several years to come. Recently CSIRO obtained decommissioned radiocarbon gas proportional counters and targets to use them for 85Kr. We aim for a sample size of 50μL Kr corresponding to the gas extracted from 500-1000L water. Flinders University and CSIRO have developed a field-deployable extraction system for large volume gas-extraction in the field. It uses two membrane contactors (MEMBRANA SuperPhobic 4x13) allowing flow rates of up to 50L/min in serial mode. Switching to parallel flow through both contactors is possible, allowing even higher water flow rates. The system automatically logs water temperature, water pressure, water flow rate, gas pressure of the sample, vacuum pressure at the contactor and all valve states, using an Endress + Hauser RSG40 Memograph M. The use of SuperPhobic contactors results in ten times less water in the gas fraction than reported for earlier systems. With the two contactors in serial configuration, gas extraction efficiencies, determined for O2, N2 and Ar, are better than 95% at 5L/min water flow. They are still above 80% for flow rates up to 20L/min in parallel configuration for O2, N2 and Ar. No measurable isotopic fractionation of the target isotope ratios of argon and krypton is to be expected at these high extraction efficiencies.

  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. 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.

  7. Using gas geochemistry to delineate structural compartments and assess petroleum reservoir-filling directions: A Venezuelan case study

    NASA Astrophysics Data System (ADS)

    Márquez, G.; Escobar, M.; Lorenzo, E.; Gallego, J. R.; Tocco, R.

    2013-04-01

    Here we examined the light hydrocarbon and nitrogen content and isotopic signatures of eleven gaseous samples in order to evaluate lateral intra-reservoir continuity in a Venezuelan reservoir in the central area of Lake Maracaibo Basin. At least three single compartments, located in the northern-central and southern parts of the reservoir, are revealed by nitrogen concentrations showing clear step-like compositional breaks. The occurrence of step-breaks was also supported by the isotopic signature of individual hydrocarbon compounds in the range of C1-C4 alkanes. Samples presented only slight differences in N2 and hydrocarbon gas compositions within the central and northern parts of the reservoir, and therefore it was not possible to infer structural barriers in coherence with the geological section. Some oil bulk parameters corroborate gradual changes that provide additional information on the reservoir-filling history, thus suggesting that the lateral physical-chemical equilibrium of fluids was not reached in this reservoir.

  8. 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. PMID:23879082

  9. 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. PMID:24104822

  10. Efficient anti-Stokes generation via intermodal stimulated Raman scattering in gas-filled hollow-core PCF.

    PubMed

    Trabold, B M; Abdolvand, A; Euser, T G; Russell, P St J

    2013-12-01

    A strong anti-Stokes Raman signal, from the vibrational Q(1) transition of hydrogen, is generated in gas-filled hollow-core photonic crystal fiber. To be efficient, this process requires phase-matching, which is not automatically provided since the group velocity dispersion is typically non-zero and--inside a fiber--cannot be compensated for using a crossed-beam geometry. Phase-matching can however be arranged by exploiting the different dispersion profiles of higher-order modes. We demonstrate the generation of first and second anti-Stokes signals in higher-order modes by pumping with an appropriate mixture of fundamental and a higher-order modes, synthesized using a spatial light modulator. Conversion efficiencies as high as 5.3% are achieved from the pump to the first anti-Stokes band. PMID:24514522

  11. Accelerator mass spectrometry of 63Ni using a gas-filled magnet at the Munich Tandem Laboratory

    NASA Astrophysics Data System (ADS)

    Rugel, G.; Faestermann, T.; Knie, K.; Korschinek, G.; Marchetti, A. A.; McAninch, J. E.; Rühm, W.; Straume, T.; Wallner, C.

    2000-10-01

    The detection of 63Ni ( T1/2=100.1 yr) by means of accelerator mass spectrometry (AMS) using a gas-filled magnet (GFM) is described. The experimental setup includes a dedicated ion source, a 14 MV MP tandem, a GFM and a multi-anode ionization chamber. First results indicate a background level of 63Ni/Ni ratios as low as 2×10 -14. This sensitivity will allow - for the first time ever - to detect 63Ni induced by fast neutrons in copper samples from Hiroshima and Nagasaki, even for distances beyond 1500 m from the hypocenters. Thus, it will be possible to reconstruct experimentally the neutron doses of the A-bomb survivors from Hiroshima and Nagasaki.

  12. Pulsed microwave discharge in a capillary filled with atmospheric-pressure gas

    SciTech Connect

    Gritsinin, S. I.; Gushchin, P. A.; Davydov, A. M.; Ivanov, E. V.; Kossyi, I. A.

    2013-08-15

    A pulsed microwave coaxial capillary plasma source generating a thin plasma filament along the capillary axis in an atmospheric-pressure argon flow is described. The dynamics of filament formation is studied, and the parameters of the gas and plasma in the contraction region are determined. A physical model of discharge formation and propagation is proposed. The model is based on the assumption that, under the conditions in which the electric fields is substantially below the threshold value, the discharge operates in a specific form known as a self-sustained-non-self-sustained (SNS) microwave discharge.

  13. Calculations for NIF first quad gas-filled hohlraum experiments testing beryllium microstructure growth and laser plasma interaction physics

    SciTech Connect

    Goldman, S. R.; Fernández, J. C.; Hoffman, N. M.; Kindel, J. M.; Langdon, A. Bruce

    2004-01-01

    The first quad of the NIF provides four nearly collinear f/20 laser beams, which can be treated as a single f/8 beam of maximum energy 16 kJ. We are designing experiments on halfraums in which the composite beam is focused in the plane of the (single) halfraum laser entry hole (LEH) with its symmetry axis collinear with the halfiaum symmetry axis. For most of the calculations, the halfraum diameter is 1.6mm, the LEH is 1.2mm, and axial length is 3.0mm. The incident laser power consists of an early foot followed by a final peak. Peak radiation temperatures for this relatively narrow hohlraum are greater than for wider hohlraums of the same length. Plasma conditions within the halfraum are calculated with Lasnex using azimuthally symmetric, (r,z) geometry, taking into account a polyimide membrane which contains the fill gas (CH{sub 2}) within the halfraum. Estimates for microstructure growth due to the volume crystalline structure within a beryllium slab mounted in the halfraum sidewall are obtained by a post-processor, which applies plasma conditions within the halfraum to an ablatively accelerated, two-dimensional beryllium slab. We present a detailed simulation of the hohlraum conditions resulting from a laser spot of diameter 500 {mu}m, with peak intensity at 3.5 x 10{sup 15} W/cm{sup 2}, a comparison with a simulation with the same power-time profile at an intensity about 1/4 as great, and a comparison with a simulation with more detailed attention to hydro coupling between the gold and gas-fill regions of the hohlraum. We are currently attempting to model the consequences of possible beam filamentation during the pulse.

  14. 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.

  15. Bulk manufacture of concentrated oxygen gas-filled microparticles for intravenous oxygen delivery.

    PubMed

    Kheir, John N; Polizzotti, Brian D; Thomson, Lindsay M; O'Connell, Daniel W; Black, Katherine J; Lee, Robert W; Wilking, James N; Graham, Adam C; Bell, David C; McGowan, Francis X

    2013-08-01

    Self-assembling, concentrated, lipid-based oxygen microparticles (LOMs) have been developed to administer oxygen gas when injected intravenously, preventing organ injury and death from systemic hypoxemia in animal models. Distinct from blood substitutes, LOMs are a one-way oxygen carrier designed to rescue patients who experience life-threatening hypoxemia, as caused by airway obstruction or severe lung injury. Here, we describe methods to manufacture large quantities of LOMs using an in-line, recycling, high-shear homogenizer, which can create up to 4 liters of microparticle emulsion in 10 minutes, with particles containing a median diameter of 0.93 microns and 60 volume% of gas phase. Using this process, we screen 30 combinations of commonly used excipients for their ability to form stable LOMs. LOMs composed of DSPC and cholesterol in a 1:1 molar ratio are stable for a 100 day observation period, and the number of particles exceeding 10 microns in diameter does not increase over time. When mixed with blood in vitro, LOMs fully oxygenate blood within 3.95 seconds of contact, and do not cause hemolysis or complement activation. LOMs can be manufactured in bulk by high shear homogenization, and appear to have a stability and size profile which merit further testing. PMID:23471884

  16. 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.

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

    DOE PAGESBeta

    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 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

  18. Supernova Feedback and the Hot Gas Filling Fraction of the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Li, Miao; Ostriker, Jeremiah P.; Cen, Renyue; Bryan, Greg L.; Naab, Thorsten

    2015-11-01

    Supernovae (SNe), the most energetic stellar feedback mechanism, are crucial for regulating the interstellar medium (ISM) and launching galactic winds. We explore how supernova remnants (SNRs) create a multiphase medium by performing three-dimentional hydrodynamical simulations at various SN rates, S, and ISM average densities, \\bar{n}. The evolution of an SNR in a self-consistently generated three-phase ISM is qualitatively different from that in a uniform or a two-phase warm/cold medium. By traveling faster and further in the low-density hot phase, the domain of an SNR increases by >102.5. Varying \\bar{n} and S, we find that a steady state can only be achieved when the hot gas volume fraction {f}{{V,hot}}≲ 0.6+/- 0.1. Above that level, overlapping SNRs render connecting topology of the hot gas, and the ISM is subjected to thermal runaway. Photoelectric heating (PEH) has a surprisingly strong impact on {f}{{V,hot}}. For \\bar{n}≳ 3 {{cm}}-3, a reasonable PEH rate is able to suppress the thermal runaway. Overall, we determine the critical SN rate for the onset of thermal runaway to be {S}{{crit}}=200{(\\bar{n}/1 {{cm}}-3)}k{({E}{{SN}}/{10}51 {{erg}})}-1 {{{kpc}}}-3 {{Myr}}-1, where k = (1.2, 2.7) for \\bar{n}≤slant 1 and \\gt 1 {{cm}}-3, respectively. We present a fitting formula of the ISM pressure P(\\bar{n},S), which can be used as an effective equation of state in cosmological simulations. Despite the five orders of magnitude span of (\\bar{n},S), the average Mach number varies little: {M} ≈ 0.5 ± 0.2, 1.2 ± 0.3, and 2.3 ± 0.9 for the hot, warm, and cold phases, respectively.

  19. Theoretical investigation of rare gas hydride cations: HRgN2+ (Rg=He, Ar, Kr, and Xe)

    NASA Astrophysics Data System (ADS)

    Jayasekharan, T.; Ghanty, T. K.

    2012-04-01

    Rare gas containing protonated nitrogen cations, HRgN2+ (Rg=He, Ar, Kr, and Xe), have been predicted using quantum computational methods. HRgN2+ ions exhibit linear structure (C∞v symmetry) at the minima and show planar structure (Cs symmetry) at the transition state. The stability is determined by computing the energy differences between the predicted ions and its various unimolecular dissociation products. Analysis of energy diagram indicates that HXeN2+ is thermodynamically stable with respect to dissociated products while HHeN2+, HArN2+, and HKrN2+ ions are metastable with small barrier heights. Moreover, the computed intrinsic reaction coordinate analysis also confirms that the minima and the 2-body global dissociation products are connected through transition states for the metastable ions. The coupled-cluster theory computed dissociation energies corresponding to the 2-body dissociation (HN2+ + Rg) is -288.4, -98.3, -21.5, and 41.4 kJ mol-1 for HHeN2+, HArN2+, HKrN2+, and HXeN2+ ions, respectively. The dissociation energies are positive for all the other channels implying that the predicted ions are stable with respect to other 2- and 3-body dissociation channels. Atoms-in-molecules analysis indicates that predicted ions may be best described as HRg+N2. It should be noted that the energetic of HXeN2+ ion is comparable to that of the experimentally observed stable mixed cations, viz. (RgHRg')+. Therefore, it may be possible to prepare and characterize HXeN2+ ions in an electron bombardment matrix isolation technique.

  20. Analysis of burns caused by pre-filled gas canisters used for lamps or portable camping stoves.

    PubMed

    Desouches, C; Salazard, B; Romain, F; Karra, C; Lavie, A; Volpe, C Della; Manelli, J C; Magalon, G

    2006-12-01

    The use of pre-filled valveless gas canisters for lamps or camping stoves has caused a number of serious burn incidents. We performed a retrospective analysis of all of the patients who were victims of such incidents admitted to the Marseille Burn Centre between January 1990 and March 2004. There were a total of 21 patients burned in such conditions. Adult males made up the majority of the victims of this sort. Lesions were often extensive (60% of the patients were burned over more than 10% of their body surface) and systematically deep. In order of frequency, burn locations were: the lower limbs, the upper limbs, the hands and the face. The incidents principally occurred during replacement of the canister near an open flame. The marketing of a canister with a valve in order to avoid gas leaks did not cause the old canisters to be taken off the market. On the contrary, European Safety Standard EN417, updated in October 2003, validated the use of these valveless canisters. The severity of the lesions caused and the existence of safe equivalent products requires the passage of a law that forbids valveless canisters. PMID:16982156

  1. Three-dimensional fluid pressure mapping in porous media using magnetic resonance imaging with gas-filled liposomes.

    PubMed

    Morris, Robert H; Bencsik, Martin; Vangala, Anil K; Perrie, Yvonne

    2007-05-01

    This paper presents and demonstrates a method for using magnetic resonance imaging to measure local pressure of a fluid saturating a porous medium. The method is tested both in a static system of packed silica gel and in saturated sintered glass cylinders experiencing fluid flow. The fluid used contains 3% gas in the form of 3-mum average diameter gas filled 1,2-distearoyl-sn-glycero-3-phosphocholine (C18:0, MW: 790.16) liposomes suspended in 5% glycerol and 0.5% Methyl cellulose with water. Preliminary studies at 2.35 T demonstrate relative magnetic resonance signal changes of 20% per bar in bulk fluid for an echo time T(E)=40 ms, and 6-10% in consolidated porous media for T(E)=10 ms, over the range 0.8-1.8 bar for a spatial resolution of 0.1 mm(3) and a temporal resolution of 30 s. The stability of this solution with relation to applied pressure and methods for improving sensitivity are discussed. PMID:17466775

  2. High harmonic generation in a gas-filled hollow-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Heckl, O. H.; Baer, C. R. E.; Kränkel, C.; Marchese, S. V.; Schapper, F.; Holler, M.; Südmeyer, T.; Robinson, J. S.; Tisch, J. W. G.; Couny, F.; Light, P.; Benabid, F.; Keller, U.

    2009-10-01

    High harmonic generation (HHG) of intense infrared laser radiation (Ferray et al., J. Phys. B: At. Mol. Opt. Phys. 21:L31, 1988; McPherson et al., J. Opt. Soc. Am. B 4:595, 1987) enables coherent vacuum-UV (VUV) to soft-X-ray sources. In the usual setup, energetic femtosecond laser pulses are strongly focused into a gas jet, restricting the interaction length to the Rayleigh range of the focus. The average photon flux is limited by the low conversion efficiency and the low average power of the complex laser amplifier systems (Keller, Nature 424:831, 2003; Südmeyer et al., Nat. Photonics 2:599, 2008; Röser et al., Opt. Lett. 30:2754, 2005; Eidam et al., IEEE J. Sel. Top. Quantum Electron. 15:187, 2009) which typically operate at kilohertz repetition rates. This represents a severe limitation for many experiments using the harmonic radiation in fields such as metrology or high-resolution imaging. Driving HHG with novel high-power diode-pumped multi-megahertz laser systems has the potential to significantly increase the average photon flux. However, the higher average power comes at the expense of lower pulse energies because the repetition rate is increased by more than a thousand times, and efficient HHG is not possible in the usual geometry. So far, two promising techniques for HHG at lower pulse energies were developed: external build-up cavities (Gohle et al., Nature 436:234, 2005; Jones et al., Phys. Rev. Lett. 94:193, 2005) and resonant field enhancement in nanostructured targets (Kim et al., Nature 453:757, 2008). Here we present a third technique, which has advantages in terms of ease of HHG light extraction, transverse beam quality, and the possibility to substantially increase conversion efficiency by phase-matching (Paul et al., Nature 421:51, 2003; Ren et al., Opt. Express 16:17052, 2008; Serebryannikov et al., Phys. Rev. E (Stat. Nonlinear Soft Matter Phys.) 70:66611, 2004; Serebryannikov et al., Opt. Lett. 33:977, 2008; Zhang et al., Nat. Phys. 3

  3. 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.

  4. 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.

  5. 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.

  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. 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.

  8. Effects of total CH 4/Ar gas pressure on the structures and field electron emission properties of carbon nanomaterials grown by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Qi, J. L.; Wang, X.; Zheng, W. T.; Tian, H. W.; Liu, C.; Lu, Y. L.; Peng, Y. S.; Cheng, G.

    2009-12-01

    The effects of total CH 4/Ar gas pressure on the growth of carbon nanomaterials on Si (1 0 0) substrate covered with CoO nanoparticles, using plasma-enhanced chemical vapor deposition (PECVD), were investigated. The structures of obtained products were correlated with the total gas pressure and changed from pure carbon nanotubes (CNTs) through hybrid CNTs/graphene sheets (GSs), to pure GSs as the total gas pressure changed from 20 to 4 Torr. The total gas pressure influenced the density of hydrogen radicals and Ar ions in chamber, which in turn determined the degree of how CoO nanoparticles were deoxidized and ion bombardment energy that governed the final carbon nanomaterials. Moreover, the obtained hybrid CNTs/GSs exhibited a lower turn-on field (1.4 V/μm) emission, compared to either 2.7 V/μm for pure CNTs or 2.2 V/μm for pure GSs, at current density of 10 μA/cm 2.

  9. Investigating the double-peaked K-shell pulse emitted by the Xe-doped Ar gas-puff shot Z 2603

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    A recent series of Ar gas-puff experiments on Sandia National Laboratories' Z generator achieved K-shell yields in excess of 300 kJ. However, when a Xe dopant of 0.8% by number was added to the central jet, the K-shell yield was reduced by a factor of 3, and, only on this shot, it appeared in two distinct, nearly equal peaks. We investigate possible causes of this phenomenon in terms of the evolving properties of the pinch, and the temperature sensitivity of Ar K-shell emissivity. Work supported by DOE/NNSA and by Sandia National Laboratories under DOE Contract No. DE-AC04-94AL85000.

  10. Indium-tin oxide thin films deposited at room temperature on glass and PET substrates: Optical and electrical properties variation with the H2-Ar sputtering gas mixture

    NASA Astrophysics Data System (ADS)

    Álvarez-Fraga, L.; Jiménez-Villacorta, F.; Sánchez-Marcos, J.; de Andrés, A.; Prieto, C.

    2015-07-01

    The optical and electrical properties of indium tin oxide (ITO) films deposited at room temperature on glass and polyethylene terephthalate (PET) substrates were investigated. A clear evolution of optical transparency and sheet resistance with the content of H2 in the gas mixture of H2 and Ar during magnetron sputtering deposition is observed. An optimized performance of the transparent conductive properties ITO films on PET was achieved for samples prepared using H2/(Ar + H2) ratio in the range of 0.3-0.6%. Moreover, flexible ITO-PET samples show a better transparent conductive figure of merit, ΦTC = T10/RS, than their glass counterparts. These results provide valuable insight into the room temperature fabrication and development of transparent conductive ITO-based flexible devices.

  11. Development of the Focal Plane Detection System for the Future Gas-Filled Separator at the Cyclotron Institute

    NASA Astrophysics Data System (ADS)

    Bertelsen, Erin; Mayorov, Dmitriy; Folden, Charles ``Cody'', III

    2015-10-01

    A focal plane detection system is being developed for use with the gas-filled separator previously known as SASSYER (Small Angle Separator System at Yale for Evaporation Residues) that will be installed at the Cyclotron Institute at Texas A&M University. This system will be used to study heavy (Z >= 90) elements and features two 60×40 strip double-sided silicon detectors (DSSDs) and accompanying multiplexing read-out electronics. The DSSDs cover an area of 120×40 mm2 and are read-out by fourteen 16-channel multiplexers (Mesytec MUX-16) that perform the function of a preamplifier, shaper, and leading-edge discriminator in one unit. The multiplexers are controlled by four ``MUX drivers,'' each of which serves as a signal bus for multiple MUX-16 boards. The system allows a single 16-channel ADC to read the combined 200 strips of both DSSDs. A four peak source composed of 148Gd, 239Pu, 241Am, and 244Cm was used to characterize the performance of the system, with a preliminary energy resolution of ~ 60 keV measured for the 241Am alphas. This contribution will discuss the work performed in assembly of the test setup, optimization and performance check of the multiplexers, and the preliminary energy and position data collected with the α-source. Present address: Los Alamos National Laboratory, Los Alamos, NM 87545.

  12. Understanding fast neutrons utilizing a water Cherenkov detector and a gas-filled detector at the soudan underground laboratory

    NASA Astrophysics Data System (ADS)

    Ghimire, Chiranjibi

    Many experiments are currently searching for Weakly Interactive Massive Particles (WIMPs), a well-motivated class of hypothetical dark matter candidates. These direct dark matter detection experiments are located in deep underground to shield from cosmic-ray muons and the fast neutrons they produce. Fast neutrons are particularly dangerous to WIMP detectors because they can penetrate a WIMP-search experiment's neutron shielding. Once inside, these fast neutrons can interact with high-Z material near the WIMP detector, producing slower neutrons capable of mimicking the expected WIMP signal. My research uses two detectors located in Soudan Underground Laboratory to understand fast neutron production by muons in an underground environment: a water-Cherenkov detector sensitive to fast neutrons; and a gas-filled detector sensitive to charged particles like muons. The different kinds of selection criterion and their efficiencies are reported in this thesis. This thesis estimate the number of high energy neutron-like candidates associated with a nearby muon by using data from both detector systems.

  13. Portable optical frequency standard based on sealed gas-filled hollow-core fiber using a novel encapsulation technique

    NASA Astrophysics Data System (ADS)

    Triches, Marco; Brusch, Anders; Hald, Jan

    2015-12-01

    A portable stand-alone optical frequency standard based on a gas-filled hollow-core photonic crystal fiber is developed to stabilize a fiber laser to the ^{13}{C}_2{H}_2 P(16) (ν _1 + ν _3) transition at 1542 nm using saturated absorption. A novel encapsulation technique is developed to permanently seal the hollow-core fiber with easy light coupling, showing negligible pressure increase over two months. The locked laser shows a fractional frequency instability below 8 × 10^{-12} for an averaging time up to 104 s. The lock-point repeatability over one month is 2.6 × 10^{-11}, corresponding to a standard deviation of 5.3 kHz. The system is also assembled in a more compact and easy-to-use configuration ( Plug&Play), showing comparable performance with previously published work. The real portability of this technology is proved by shipping the system to a collaborating laboratory, showing unchanged performance after the return.

  14. Experimental tests of Rayleigh-Taylor stabilization mechanisms with long pulse gas-filled halfraums on OMEGA

    NASA Astrophysics Data System (ADS)

    Casner, A.; Huser, G.; Vandenboomgaerde, M.; Liberatore, S.; Masse, L.; Galmiche, D.

    2008-11-01

    Mitigation of Rayleigh-Taylor instabilities growth is a key issue on the road toward ignition. The graded doped ablator is a common concept for NIF [1] and LMJ [2] point designs. A complementary stabilization mechanism based on anisotropic thermal diffusion was theoretically underlined [3] for the ablative Rayleigh-Taylor instability. We will present the first ever experimental tests of these mechanisms. Indirect drive experiments were performed on the OMEGA laser facility with a long-pulse platform. We used in fact gas-filled halfraums and stack 15 drive beams along 2 cones to create a 7 ns long radiation drive. Halfraum energetics with E-IDI-300 phase plates was validated by dedicated shots along P5/P8 and is fairly reproduced by the simulations. These drive measurements allowed also to determine the graded doped planar emulator whose layers thicknesses and composition should be carefully optimized . Side-on and face-on data acquired with germanium-doped plastic samples (modulations wavelength 35 and 50 microns) will be presented and compared with FCI2 hydrocodes simulations. [1] S.W. Haan et al., Phys. Plasmas 12, 056316 (2005). [2] C C-Cl'erouin et al 2008 J. Phys.: Conf. Ser. 112 022023 [3] L. Masse., Phys. Rev. Lett. 98, 245001 (2007).

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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 Bi2Se3 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. Dependence of charge collection distributions and dose on the gas type filling the ionization chamber for a p(66)Be(49) clinical neutron beam

    SciTech Connect

    Awschalom, M.; Haken, R.K.T.

    1985-01-01

    Measurements of central axis depth charge distributions (CADCD) in a p(66)Be(49) clinical neutron beam using A-150 TE plastic ionization chambers (IC) have shown that these distributions are dependent on the gas type filling the ICs. IC volumes from 0.1 to 8 cm/sup 3/ and nine different gases were investigated. Off axis ratios and build-up measurements do not seem to be as sensitive to gas type. The gas dosimetry constants given in the AAPM Protocol for Neutron Beam Dosimetry for air and methane based TE gases were tested for consistency in water and in TE solution filled phantoms at depths of 10 cm, when used in conjunction with an IC having 5 mm thick walls of A-150. 29 refs., 7 figs., 1 tab.

  17. 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.

  18. 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.

  19. Effective ionization coefficients, limiting electric fields, and electron energy distributions in CF3I + CF4 + Ar ternary gas mixtures

    NASA Astrophysics Data System (ADS)

    Tezcan, S. S.; Dincer, M. S.; Bektas, S.

    2016-07-01

    This paper reports on the effective ionization coefficients, limiting electric fields, electron energy distribution functions, and mean energies in ternary mixtures of (Trifluoroiodomethane) CF3I + CF4 + Ar in the E/N range of 100-700 Td employing a two-term solution of the Boltzmann equation. In the ternary mixture, CF3I component is increased while the CF4 component is reduced accordingly and the 40% Ar component is kept constant. It is seen that the electronegativity of the mixture increases with increased CF3I content and effective ionization coefficients decrease while the limiting electric field values increase. Synergism in the mixture is also evaluated in percentage using the limiting electric field values obtained. Furthermore, it is possible to control the mean electron energy in the ternary mixture by changing the content of CF3I component.

  20. 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.

  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. 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.

  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

    NASA Astrophysics Data System (ADS)

    Machavarapu, Ramudu; Jakob, Gerhard

    2015-03-01

    We report the effect of substrate temperature (TS) and Ar gas pressure (PD) 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 TS. The observed maximum EB value of 320 Oe after field cooling in the film deposited at 650 ∘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 PD variation, with increase in PD, 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 PD. 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 PD, 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. Filling in of Fraunhofer and gas-absorption lines in sky spectra as caused by rotational Raman scattering.

    PubMed

    Sioris, C E; Evans, W F

    1999-04-20

    A line-by-line radiative-transfer model to quantify the Ring effect as caused by rotational Raman scattering has been developed for the 310-550-nm spectral interval. The solar zenith angle and the resolution are key input parameters, as is the sky spectrum (excluding inelastic atmospheric scattering), which was modeled with MODTRAN 3.5. The filling in is modeled for ground-based viewing geometry and includes surface reflection and single inelastic scattering. It is shown that O2 contributes half of the filling in of N2. A strong inverse relationship with wavelength is noted in the filling in. A comparison with observations shows moderate agreement. The largest filling in occurs in the Ca II K and H lines. PMID:18319844

  6. 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.

  7. 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.

  8. 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

    2014-03-01

    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. PMID:24521558

  9. Analysis of the insulation characteristics of CF3I gas mixtures with Ar, Xe, He, N2, and CO2 using Boltzmann equation method

    NASA Astrophysics Data System (ADS)

    Deng, Yunkun; Xiao, Dengming

    2014-09-01

    The present study is devoted to the calculation of electron swarm parameters, including the reduced effective ionization coefficient, electron mean energy, and electron drift velocity, for the gas mixtures of CF3I with Ar, Xe, He, N2, and CO2. These data are computed by employing the Boltzmann equation method with two-term approximation in the condition of steady-state Townsend (SST) discharge. For the purpose of evaluating the insulation strength of CF3I gas mixtures, values of the limiting field strength (E/N)lim for which the ionization exactly balances the electron attachment are determined from the variation curves of (α - η)/N. The results indicate that mixtures of CF3I-N2 present the greatest insulation strength among all the combinations for CF3I content varied from 20 to 90%. Furthermore, the gas mixture with 70% CF3I can achieve a very similar dielectric strength to that of SF6. The concerned liquefaction issues are also taken into account to fully assess the possibility of applying CF3I gas mixtures in power equipment as an insulation medium.

  10. A metrological approach to measuring 40Ar* concentrations in K-Ar and 40Ar/39Ar mineral standards

    NASA Astrophysics Data System (ADS)

    Morgan, Leah E.; Postma, Onno; Kuiper, Klaudia F.; Mark, Darren F.; van der Plas, Wim; Davidson, Stuart; Perkin, Michael; Villa, Igor M.; Wijbrans, Jan R.

    2011-10-01

    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 discuss the theoretical approach and technical design of a gas delivery system which emits metrologically traceable amounts of 40Ar and will allow for the sensitivity calibration of noble gas mass spectrometers. The design of this system is based on a rigorous assessment of the uncertainty budget and detailed tests of a prototype system. A number of obstacles and proposed resolutions are discussed along with the selection of components and their integration into a pipette system.