WorldWideScience

Sample records for argon hydrides

  1. Spectroscopic characterization of low power argon microwave-induced plasma with gaseous species produced from ethanol-water solutions in continuous hydride generation process

    International Nuclear Information System (INIS)

    Low power microwave-induced argon plasma generated by resonant TE101 rectangular cavity was investigated upon introduction of volatile species formed in the reaction with sodium tetraborohydrate(III) in hydrochloric acid-ethanol solution. The molecular emission bands of OH and CH were used for rotational temperature (Trot) determination, while the atomic emission lines of Ar, H and Sb were applied for excitation temperature (Texc) measurement. Assuming a Boltzmann distribution, the temperatures were calculated with the aid of the least squares method. Electron number density (ne) derived from Stark broadening of the Hβ line was found to be between 2.5x1015 and 0.57x1015 cm-3. The detection limits (DL) were determined for Hg and Sb. The influence of ethanol concentration in analyte solution and microwave power on measured parameters, was investigated. The results showed that Trot(OH) increased from 2970 to 3820 K while Trot(CH) decreased from 6100 to 4540 K with ethanol concentration in the solution, ranging from 10 to 90%. Under the same experimental conditions the excitation temperature for Ar, H and Sb varied in the following ranges: 5670-4800, 6190-3950 and 10500-7390 K, respectively. It was observed that element DL were significantly influenced by the presence of ethanol in the sample solution. The DL values for Hg and Sb were, as follows: 0.5-11 and 5.3-35 μg l-1, respectively

  2. Interstellar Hydrides

    CERN Document Server

    Gerin, Maryvonne; Goicoechea, Javier R

    2016-01-01

    Interstellar hydrides -- that is, molecules containing a single heavy element atom with one or more hydrogen atoms -- were among the first molecules detected outside the solar system. They lie at the root of interstellar chemistry, being among the first species to form in initially-atomic gas, along with molecular hydrogen and its associated ions. Because the chemical pathways leading to the formation of interstellar hydrides are relatively simple, the analysis of the observed abundances is relatively straightforward and provides key information about the environments where hydrides are found. Recent years have seen rapid progress in our understanding of interstellar hydrides, thanks largely to far-IR and submillimeter observations performed with the Herschel Space Observatory. In this review, we will discuss observations of interstellar hydrides, along with the advanced modeling approaches that have been used to interpret them, and the unique information that has thereby been obtained.

  3. Metal Hydrides for Rechargeable Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Valoeen, Lars Ole

    2000-03-01

    Rechargeable battery systems are paramount in the power supply of modern electronic and electromechanical equipment. For the time being, the most promising secondary battery systems for the future are the lithium-ion and the nickel metal hydride (NiMH) batteries. In this thesis, metal hydrides and their properties are described with the aim of characterizing and improving those. The thesis has a special focus on the AB{sub 5} type hydrogen storage alloys, where A is a rare earth metal like lanthanum, or more commonly misch metal, which is a mixture of rare earth metals, mainly lanthanum, cerium, neodymium and praseodymium. B is a transition metal, mainly nickel, commonly with additions of aluminium, cobalt, and manganese. The misch metal composition was found to be very important for the geometry of the unit cell in AB{sub 5} type alloys, and consequently the equilibrium pressure of hydrogen in these types of alloys. The A site substitution of lanthanum by misch metal did not decrease the surface catalytic properties of AB{sub 5} type alloys. B-site substitution of nickel with other transition elements, however, substantially reduced the catalytic activity of the alloy. If the internal pressure within the electrochemical test cell was increased using inert argon gas, a considerable increase in the high rate charge/discharge performance of LaNi{sub 5} was observed. An increased internal pressure would enable the utilisation of alloys with a high hydrogen equivalent pressure in batteries. Such alloys often have favourable kinetics and high hydrogen diffusion rates and thus have a potential for improving the high current discharge rates in metal hydride batteries. The kinetic properties of metal hydride electrodes were found to improve throughout their lifetime. The activation properties were found highly dependent on the charge/discharge current. Fewer charge/discharge cycles were needed to activate the electrodes if a small current was used instead of a higher

  4. Hysteresis in Metal Hydrides.

    Science.gov (United States)

    Flanagan, Ted B., And Others

    1987-01-01

    This paper describes a reproducible process where the irreversibility can be readily evaluated and provides a thermodynamic description of the important phenomenon of hysteresis. A metal hydride is used because hysteresis is observed during the formation and decomposition of the hydride phase. (RH)

  5. Mound Laboratory activities in chemical and physical research: July--December 1976. [Isotope separation; metal hydride research, separation chemistry and separation research

    Energy Technology Data Exchange (ETDEWEB)

    1977-05-04

    The status of the following programs is reported: isotope separation of carbon, argon, helium, krypton, neon, xenon, oxygen, and sulfur; metal hydride research; separation chemistry; and separation research. (LK)

  6. Regenerative Hydride Heat Pump

    Science.gov (United States)

    Jones, Jack A.

    1992-01-01

    Hydride heat pump features regenerative heating and single circulation loop. Counterflow heat exchangers accommodate different temperatures of FeTi and LaNi4.7Al0.3 subloops. Heating scheme increases efficiency.

  7. Lightweight hydride storage materials

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, G.J.; Guthrie, S.E.; Bauer, W. [Sandia National Labs., Livermore, CA (United States)

    1995-09-01

    The need for lightweight hydrides in vehicular applications has prompted considerable research into the use of magnesium and its alloys. Although this earlier work has provided some improved performance in operating temperature and pressure, substantial improvements are needed before these materials will significantly enhance the performance of an engineered system on a vehicle. We are extending the work of previous investigators on Mg alloys to reduce the operating temperature and hydride heat of formation in light weight materials. Two important results will be discussed in this paper: (1) a promising new alloy hydride was found which has better pressure-temperature characteristics than any previous Mg alloy and, (2) a new fabrication process for existing Mg alloys was developed and demonstrated. The new alloy hydride is composed of magnesium, aluminum and nickel. It has an equilibrium hydrogen overpressure of 1.3 atm. at 200{degrees}C and a storage capacity between 3 and 4 wt.% hydrogen. A hydrogen release rate of approximately 5 x 10{sup -4} moles-H{sub 2}/gm-min was measured at 200{degrees}C. The hydride heat of formation was found to be 13.5 - 14 kcal/mole-H{sub 2}, somewhat lower than Mg{sub 2}Ni. The new fabrication method takes advantage of the high vapor transport of magnesium. It was found that Mg{sub 2}Ni produced by our low temperature process was better than conventional materials because it was single phase (no Mg phase) and could be fabricated with very small particle sizes. Hydride measurements on this material showed faster kinetic response than conventional material. The technique could potentially be applied to in-situ hydride bed fabrication with improved packing density, release kinetics, thermal properties and mechanical stability.

  8. Conference 'Chemistry of hydrides' Proceedings

    International Nuclear Information System (INIS)

    This collection of thesis of conference of Chemistry hydrides presents the results of investigations concerning of base questions of chemistry of nonorganic hydrides, including synthesis questions, studying of physical and chemical properties, thermodynamics, analytical chemistry, investigation of structure, equilibriums in the systems of metal-hydrogen, behaviour of nonorganic hydrides in non-water mediums and applying investigations in the chemistry area and technology of nonorganic hydrides

  9. Air and metal hydride battery

    Energy Technology Data Exchange (ETDEWEB)

    Lampinen, M.; Noponen, T. [Helsinki Univ. of Technology, Otaniemi (Finland). Lab. of Applied Thermodynamics

    1998-12-31

    The main goal of the air and metal hydride battery project was to enhance the performance and manufacturing technology of both electrodes to such a degree that an air-metal hydride battery could become a commercially and technically competitive power source for electric vehicles. By the end of the project it was possible to demonstrate the very first prototype of the air-metal hydride battery at EV scale, achieving all the required design parameters. (orig.)

  10. Depleted Argon from Underground Sources

    International Nuclear Information System (INIS)

    Argon is a strong scintillator and an ideal target for Dark Matter detection; however 39Ar contamination in atmospheric argon from cosmic ray interactions limits the size of liquid argon dark matter detectors due to pile-up. Argon from deep underground is depleted in 39Ar due to the cosmic ray shielding of the earth. In Cortez, Colorado, a CO2 well has been discovered to contain approximately 600 ppm of argon as a contamination in the CO2. We first concentrate the argon locally to 3% in an Ar, N2, and He mixture, from the CO2 through chromatographic gas separation, and then the N2 and He will be removed by continuous distillation to purify the argon. We have collected 26 kg of argon from the CO2 facility and a cryogenic distillation column is under construction at Fermilab to further purify the argon.

  11. Argon in action

    CERN Multimedia

    Corinne Pralavorio

    2015-01-01

    Over the past few days, the SPS has been accelerating argon ions, which have started to be sent to the NA61/SHINE experiment. This operating mode, using a new type of ion, required a number of modifications to the accelerator.   Picture 1: a “super-cycle” of the SPS, featuring a proton cycle for the LHC, followed by an argon ion cycle for the North Area. Today, the accelerators are once again juggling particles and even performing completely new tricks. The SPS is supplying beams of argon ions for the first time, at energies never before achieved for this type of beam. They are destined for the NA61/SHINE experiment (see box) located in the North Area, which began receiving the beams on 11 February. Argon ions have a relatively large mass, as they consist of 40 nucleons, so they can be used in a similar way to lead ions. The main difficulty in accelerating them lies in the SPS, where the variation in acceleration frequency is limited. “The SPS was designed for a...

  12. Thermophysical properties of argon

    Energy Technology Data Exchange (ETDEWEB)

    Jaques, A.

    1988-02-01

    The entire report consists of tables of thermodynamic properties (including sound velocity, thermal conductivity and diffusivity, Prandtl number, density) of argon at 86 to 400/degree/K, in the form of isobars over 0.9 to 100 bars. (DLC)

  13. Erbium hydride decomposition kinetics.

    Energy Technology Data Exchange (ETDEWEB)

    Ferrizz, Robert Matthew

    2006-11-01

    Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.

  14. Metal hydride air conditioner

    Institute of Scientific and Technical Information of China (English)

    YANG; Ke; DU; Ping; LU; Man-qi

    2005-01-01

    The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs of hydrogen storage alloys, LaNi4.4 Mn0.26 Al0.34 / La0.6 Nd0.4 Ni4.8 Mn0.2 Cu0. 1, LaNi4.61Mn0. 26 Al0.13/La0.6 Nd0.4 Ni4.8 Mn0.2 Cu0. 1 and LaNi4.61 Mn0.26 Al0.13/La0.6 Y0.4 Ni4.8 Mn0. 2, were selected as the working materials for the metal hydride air conditioning system. Studies on the factors affecting the COP of the system showed that higher COP and available hydrogen content need the proper operating temperature and cycling time,large hydrogen storage capacity, flat plateau and small hysterisis of hydrogen alloys, proper original input hydrogen content and mass ratio of the pair of alloys. It also needs small conditioning system was established by using LaNi4.61 Mn0.26 Al0. 13/La0.6 Y0.4 Ni4.8 Mn0.2 alloys as the working materials, which showed that under the operating temperature of 180℃/40℃, a low temperature of 13℃ was reached, with COP =0.38 and Wnet =0.09 kW/kg.

  15. Hydride development for hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, G.J.; Guthrie, S.E.; Bauer, W.; Yang, N.Y.C. [Sandia National Lab., Livermore, CA (United States); Sandrock, G. [SunaTech, Inc., Ringwood, NJ (United States)

    1996-10-01

    The purpose of this project is to develop and demonstrate improved hydride materials for hydrogen storage. The work currently is organized into four tasks: hydride development, bed fabrication, materials support for engineering systems, and IEA Annex 12 activities. At the present time, hydride development is focused on Mg alloys. These materials generally have higher weight densities for storing hydrogen than rare earth or transition metal alloys, but suffer from high operating temperatures, slow kinetic behavior and material stability. The authors approach is to study bulk alloy additions which increase equilibrium overpressure, in combination with stable surface alloy modification and particle size control to improve kinetic properties. This work attempts to build on the considerable previous research in this area, but examines specific alloy systems in greater detail, with attention to known phase properties and structures. The authors have found that specific phases can be produced which have significantly improved hydride properties compared to previous studies.

  16. Geoneutrino and Hydridic Earth model

    CERN Document Server

    Bezrukov, Leonid

    2013-01-01

    Uranium, Thorium and Potassium-40 abundances in the Earth were calculated in the frame of Hydridic Earth model. Terrestrial heat producton from U, Th and K40 decays was calculated also. We must admit the existance of Earth expansion process to understand the obtained large value of terrestrial heat producton. The geoneutrino detector with volume more than 5 kT (LENA type) must be constructed to definitely separate between Bulk Silicat Earth model and Hydridic Earth model.

  17. Physics of hydride fueled PWR

    Science.gov (United States)

    Ganda, Francesco

    The first part of the work presents the neutronic results of a detailed and comprehensive study of the feasibility of using hydride fuel in pressurized water reactors (PWR). The primary hydride fuel examined is U-ZrH1.6 having 45w/o uranium: two acceptable design approaches were identified: (1) use of erbium as a burnable poison; (2) replacement of a fraction of the ZrH1.6 by thorium hydride along with addition of some IFBA. The replacement of 25 v/o of ZrH 1.6 by ThH2 along with use of IFBA was identified as the preferred design approach as it gives a slight cycle length gain whereas use of erbium burnable poison results in a cycle length penalty. The feasibility of a single recycling plutonium in PWR in the form of U-PuH2-ZrH1.6 has also been assessed. This fuel was found superior to MOX in terms of the TRU fractional transmutation---53% for U-PuH2-ZrH1.6 versus 29% for MOX---and proliferation resistance. A thorough investigation of physics characteristics of hydride fuels has been performed to understand the reasons of the trends in the reactivity coefficients. The second part of this work assessed the feasibility of multi-recycling plutonium in PWR using hydride fuel. It was found that the fertile-free hydride fuel PuH2-ZrH1.6, enables multi-recycling of Pu in PWR an unlimited number of times. This unique feature of hydride fuels is due to the incorporation of a significant fraction of the hydrogen moderator in the fuel, thereby mitigating the effect of spectrum hardening due to coolant voiding accidents. An equivalent oxide fuel PuO2-ZrO2 was investigated as well and found to enable up to 10 recycles. The feasibility of recycling Pu and all the TRU using hydride fuels were investigated as well. It was found that hydride fuels allow recycling of Pu+Np at least 6 times. If it was desired to recycle all the TRU in PWR using hydrides, the number of possible recycles is limited to 3; the limit is imposed by positive large void reactivity feedback.

  18. A New Reducing Regent: Dichloroindium Hydride

    Institute of Scientific and Technical Information of China (English)

    A. BABA; I. SHIBATA; N. HAYASHI

    2005-01-01

    @@ 1Introduction Among the hydride derivatives of group 13 elements, various types of aluminum hydrides and boron hydrides have been employed as powerful reduction tools. Indium hydrides have not received much attention,whereas the synthesis of indium trihydride (InH3) was reported several decades ago[1]. There have been no precedents for monometallic indium hydrides having practical reactivity, while activated hydrides such as an ate complex LiPhn InH4-n (n = 0- 2) and phosphine-coordinated indium hydrides readily reduce carbonyl compounds. In view of this background, we focused on the development of dichloroindium hydrides (Cl2InH) as novel reducing agents that bear characteristic features in both ionic and radical reactions.

  19. Hydride Olefin complexes of tantalum and niobium

    NARCIS (Netherlands)

    Klazinga, Aan Hendrik

    1979-01-01

    This thesis describes investigations on low-valent tantalum and niobium hydride and alkyl complexes, particularly the dicyclopentadienyl tantalum hydride olefin complexes Cp2Ta(H)L (L=olefin). ... Zie: Summary

  20. Luminescent properties of aluminum hydride

    Energy Technology Data Exchange (ETDEWEB)

    Baraban, A.P.; Gabis, I.E.; Dmitriev, V.A. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Dobrotvorskii, M.A., E-mail: mstislavd@gmail.com [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Kuznetsov, V.G. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Matveeva, O.P. [National Mineral Resources University, Saint Petersburg 199106 (Russian Federation); Titov, S.A. [Petersburg State University of Railway Transport, Saint-Petersburg 190031 (Russian Federation); Voyt, A.P.; Elets, D.I. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation)

    2015-10-15

    We studied cathodoluminescence and photoluminescence of α-AlH{sub 3}– a likely candidate for use as possible hydrogen carrier in hydrogen-fueled vehicles. Luminescence properties of original α-AlH{sub 3} and α-AlH{sub 3} irradiated with ultraviolet were compared. The latter procedure leads to activation of thermal decomposition of α-AlH{sub 3} and thus has a practical implementation. We showed that the original and UV-modified aluminum hydride contain luminescence centers ‐ structural defects of the same type, presumably hydrogen vacancies, characterized by a single set of characteristic bands of radiation. The observed luminescence is the result of radiative intracenter relaxation of the luminescence center (hydrogen vacancy) excited by electrons or photons, and its intensity is defined by the concentration of vacancies, and the area of their possible excitation. UV-activation of the dehydrogenation process of aluminum hydride leads to changes in the spatial distribution of the luminescence centers. For short times of exposure their concentration increases mainly in the surface regions of the crystals. At high exposures, this process extends to the bulk of the aluminum hydride and ends with a decrease in concentration of luminescence centers in the surface region. - Highlights: • Aluminum hydride contains hydrogen vacancies which serve as luminescence centers. • The luminescence is the result of radiative relaxation of excited centers. • Hydride UV-irradiation alters distribution and concentration of luminescence centers.

  1. Hydrogen, lithium, and lithium hydride production

    Science.gov (United States)

    Brown, Sam W; Spencer, Larry S; Phillips, Michael R; Powell, G. Louis; Campbell, Peggy J

    2014-03-25

    A method of producing high purity lithium metal is provided, where gaseous-phase lithium metal is extracted from lithium hydride and condensed to form solid high purity lithium metal. The high purity lithium metal may be hydrided to provide high purity lithium hydride.

  2. Liquid argon neutrino detectors

    CERN Document Server

    Battistoni, G

    2001-01-01

    The liquid argon imaging technique, as proposed for the ICARUS detector, offers the possibility to perform complementary and simultaneous measurements of neutrinos, as those of CERN to Gran Sasso beam (CNGS) and those from cosmic ray events. For the currently allowed values of the Super-Kamiokande results, the combination of both CNGS and atmospheric data will provide a precise determination of the oscillation parameters. Since one can observe and unambiguously identify nu /sub e/, nu /sub mu / and nu /sub tau / components, this technology allows to explore the full (3*3) mixing matrix. The same class of detector can be proposed for high precision measurements at a neutrino factory. (3 refs).

  3. Isentropic compression of argon

    Energy Technology Data Exchange (ETDEWEB)

    Veeser, L.R.; Ekdahl, C.A.; Oona, H. [and others

    1997-06-01

    The compression was done in an MC-1 flux compression (explosive) generator, in order to study the transition from an insulator to a conductor. Since conductivity signals were observed in all the experiments (except when the probe is removed), both the Teflon and the argon are becoming conductive. The conductivity could not be determined (Teflon insulation properties unknown), but it could be bounded as being {sigma}=1/{rho}{le}8({Omega}cm){sub -1}, because when the Teflon breaks down, the dielectric constant is reduced. The Teflon insulator problem remains, and other ways to better insulate the probe or to measure the conductivity without a probe is being sought.

  4. Thermomechanical properties of hafnium hydride

    International Nuclear Information System (INIS)

    Fine bulk samples of delta-phase Hf hydride with various hydrogen contents (CH) ranging from 1.62 to 1.72 in the atomic ratio (H/Hf) were prepared, and their thermomechanical properties were characterized. At room temperature, the sound velocity and Vickers hardness were measured. The elastic modulus was calculated from the measured sound velocity. In the temperature range from room temperature to 673 K, the thermal expansion was measured by using a dilatometer, and the linear thermal expansion coefficient was calculated. Empirical equations describing the thermomechanical properties of Hf hydride as a function of CH were proposed. (author)

  5. Depleted argon from underground sources

    Energy Technology Data Exchange (ETDEWEB)

    Back, H.O.; /Princeton U.; Alton, A.; /Augustana U. Coll.; Calaprice, F.; Galbiati, C.; Goretti, A.; /Princeton U.; Kendziora, C.; /Fermilab; Loer, B.; /Princeton U.; Montanari, D.; /Fermilab; Mosteiro, P.; /Princeton U.; Pordes, S.; /Fermilab

    2011-09-01

    Argon is a powerful scintillator and an excellent medium for detection of ionization. Its high discrimination power against minimum ionization tracks, in favor of selection of nuclear recoils, makes it an attractive medium for direct detection of WIMP dark matter. However, cosmogenic {sup 39}Ar contamination in atmospheric argon limits the size of liquid argon dark matter detectors due to pile-up. The cosmic ray shielding by the earth means that Argon from deep underground is depleted in {sup 39}Ar. In Cortez Colorado a CO{sub 2} well has been discovered to contain approximately 500ppm of argon as a contamination in the CO{sub 2}. In order to produce argon for dark matter detectors we first concentrate the argon locally to 3-5% in an Ar, N{sub 2}, and He mixture, from the CO{sub 2} through chromatographic gas separation. The N{sub 2} and He will be removed by continuous cryogenic distillation in the Cryogenic Distillation Column recently built at Fermilab. In this talk we will discuss the entire extraction and purification process; with emphasis on the recent commissioning and initial performance of the cryogenic distillation column purification.

  6. Laboratory Rotational Spectroscopy of the Interstellar Diatomic Hydride Ion SH+ (X 3Σ-)

    Science.gov (United States)

    Halfen, DeWayne; Ziurys, Lucy M.

    2016-06-01

    Diatomic hydride are among the most common molecular species in the interstellar medium (ISM). The low molecular mass and thus moments of inertia cause their rotational spectra to lie principally in the submillimeter and far-infrared regions. Diatomic hydrides, both neutral (MH) and ionic (MH+) forms, are also basic building blocks of interstellar chemistry. In ionic form, they may be the “hidden” carriers of refractory elements in dense gas. They are therefore extremely good targets for space-borne and airborne platforms such as Herschel, SOFIA, and SAFIR. However, in order to detect these species in the ISM, their rotational spectra must first be measured in the laboratory. To date, there is very little high resolution data available for many hydride species, in particular the ionic form. Using submillimeter/THz direct absorption methods in the Ziurys laboratory, spectra of the interstellar diatomic hydride SH+ (X 3Σ-) have been recorded. Recent work has concerned measurement of all three fine structure components of the fundamental rotational transition N = 1 ← 0 in the range 345 - 683 GHz. SH+ was generated from H2S and argon in an AC discharge. The data have been analyzed, and spectroscopic constants for this species have been refined. SH+ is found in Photon Dominated Regions (PDRs) and X-ray Dominated Regions (XDRs) and is thought to trace energetic processes in the ISM. These current measurements confirm recent observations of this species at submillimeter/THz wavelengths with ALMA and other ground-based telescopes.

  7. Anodematerials for Metal Hydride Batteries

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf

    1997-01-01

    This report describes the work on development of hydride forming alloys for use as electrode materials in metal hydride batteries. The work has primarily been concentrated on calcium based alloys derived from the compound CaNi5. This compound has a higher capacity compared with alloys used in today...... was developed. The parameters milling time, milling intensity, number of balls and form of the alloying metals were investigated. Based on this a final alloying technique for the subsequent preparation of electrode materials was established. The technique comprises milling for 4 hours twice possibly followed...... by annealing at 700°C for 12 hours. The alloys appeared to be nanocrystalline with an average crystallite size around 10 nm before annealing. Special steel containers was developed for the annealing of the metal powders in inert atmosphere. The use of various annealing temperatures was investigated...

  8. The Liquid Argon Purity Demonstrator

    CERN Document Server

    Adamowski, M; Dvorak, E; Hahn, A; Jaskierny, W; Johnson, C; Jostlein, H; Kendziora, C; Lockwitz, S; Pahlka, B; Plunkett, R; Pordes, S; Rebel, B; Schmitt, R; Stancari, M; Tope, T; Voirin, E; Yang, T

    2014-01-01

    The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

  9. The Liquid Argon Purity Demonstrator

    Energy Technology Data Exchange (ETDEWEB)

    Adamowski, M.; Carls, B.; Dvorak, E.; Hahn, A.; Jaskierny, W.; Johnson, C.; Jostlein, H.; Kendziora, C.; Lockwitz, S.; Pahlka, B.; Plunkett, R.; Pordes, S.; Rebel, B.; Schmitt, R.; Stancari, M.; Tope, T.; Voirin, E.; Yang, T.

    2014-07-01

    The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

  10. Nanostructured, complex hydride systems for hydrogen generation

    Directory of Open Access Journals (Sweden)

    Robert A. Varin

    2015-02-01

    Full Text Available Complex hydride systems for hydrogen (H2 generation for supplying fuel cells are being reviewed. In the first group, the hydride systems that are capable of generating H2 through a mechanical dehydrogenation phenomenon at the ambient temperature are discussed. There are few quite diverse systems in this group such as lithium alanate (LiAlH4 with the following additives: nanoiron (n-Fe, lithium amide (LiNH2 (a hydride/hydride system and manganese chloride MnCl2 (a hydride/halide system. Another hydride/hydride system consists of lithium amide (LiNH2 and magnesium hydride (MgH2, and finally, there is a LiBH4-FeCl2 (hydride/halide system. These hydride systems are capable of releasing from ~4 to 7 wt.% H2 at the ambient temperature during a reasonably short duration of ball milling. The second group encompasses systems that generate H2 at slightly elevated temperature (up to 100 °C. In this group lithium alanate (LiAlH4 ball milled with the nano-Fe and nano-TiN/TiC/ZrC additives is a prominent system that can relatively quickly generate up to 7 wt.% H2 at 100 °C. The other hydride is manganese borohydride (Mn(BH42 obtained by mechano-chemical activation synthesis (MCAS. In a ball milled (2LiBH4 + MnCl2 nanocomposite, Mn(BH42 co-existing with LiCl can desorb ~4.5 wt.% H2 at 100 °C within a reasonable duration of dehydrogenation. Practical application aspects of hydride systems for H2 generation/storage are also briefly discussed.

  11. Inhibited solid propellant composition containing beryllium hydride

    Science.gov (United States)

    Thompson, W. W. (Inventor)

    1978-01-01

    An object of this invention is to provide a composition of beryllium hydride and carboxy-terminated polybutadiene which is stable. Another object of this invention is to provide a method for inhibiting the reactivity of beryllium hydride toward carboxy-terminated polybutadiene. It was found that a small amount of lecithin inhibits the reaction of beryllium hydride with the acid groups in carboxy terminated polybutadiene.

  12. Crystal structure of gold hydride

    International Nuclear Information System (INIS)

    Highlights: • Volume expansion of metal hydrides is due to the increase in the s-band filling. • AuH structure is similar to that of Hg having one more s electron compared to Au. • Structure stability of both Hg and AuH is governed by the Hume-Rothery rule. - Abstract: A number of transition metal hydrides with close-packed metal sublattices of fcc or hcp structures with hydrogen in octahedral interstitial positions were obtained by the high-pressure-hydrogen technique described by Ponyatovskii et al. (1982). In this paper we consider volume increase of metals by hydrogenation and possible crystal structure of gold hydride in relation with the structure of mercury, the nearest neighbor of Au in the Periodic table. Suggested structure of AuH has a basic tetragonal body-centered cell that is very similar to the mercury structure Hg-t I 2. The reasons of stability for this structure are discussed within the model of Fermi sphere–Brillouin zone interactions

  13. Crystal structure of gold hydride

    Energy Technology Data Exchange (ETDEWEB)

    Degtyareva, Valentina F., E-mail: degtyar@issp.ac.ru

    2015-10-05

    Highlights: • Volume expansion of metal hydrides is due to the increase in the s-band filling. • AuH structure is similar to that of Hg having one more s electron compared to Au. • Structure stability of both Hg and AuH is governed by the Hume-Rothery rule. - Abstract: A number of transition metal hydrides with close-packed metal sublattices of fcc or hcp structures with hydrogen in octahedral interstitial positions were obtained by the high-pressure-hydrogen technique described by Ponyatovskii et al. (1982). In this paper we consider volume increase of metals by hydrogenation and possible crystal structure of gold hydride in relation with the structure of mercury, the nearest neighbor of Au in the Periodic table. Suggested structure of AuH has a basic tetragonal body-centered cell that is very similar to the mercury structure Hg-t I 2. The reasons of stability for this structure are discussed within the model of Fermi sphere–Brillouin zone interactions.

  14. Research on Metal Hydride Compressor System

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Ti-Zr series Laves phase hydrogen storage alloys with good hydrogen storage properties, such as large hydrogen capacity, rapid hydriding and dehydriding rate, high compression ratio, gentle plateau, small hysteresis, easily being activated and long cyclic stability etc. for metal hydride compressor have been investigated. In addition, a hydride compressor with special characteristics, namely, advanced filling method, good heat transfer effect and reasonable structural design etc. has also been constructed. A hydride compressor cryogenic system has been assembled coupling the compressor with a J-T micro-throttling refrigeration device and its cooling capacity can reach 0.4 W at 25 K.

  15. Synthesis and enhanced hydrogen desorption kinetics of magnesium hydride using hydriding chemical vapor synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin-Ho [Icheon Branch, Korea Institute of Ceramic Engineering and Technology (KICET), Icheon-si, Gyeonggi-do (Korea, Republic of); Kim, Byung-Goan [Korea Energy Materials Co.Ltd., 409, Daegu Technopark, 1-11, Hosan-Dong, Dalse-Gu 704-230 (Korea, Republic of); Kang, Yong-Mook, E-mail: dake@kaist.ac.kr [Department of Chemistry, Dongguk University-Seoul, 100715 Seoul (Korea, Republic of)

    2012-07-15

    Highlights: Black-Right-Pointing-Pointer We synthesized pure MgH{sub 2} by a hydriding chemical vapor synthesis process in a hydrogen atmosphere. Black-Right-Pointing-Pointer The particle size HCVS-MgH{sub 2} was drastically reduced to the sub-micron or micrometer-scale. Black-Right-Pointing-Pointer HCVS-MgH{sub 2} showed different shapes (needle-like nanofibers and angulated plate) depending on the deposited position. Black-Right-Pointing-Pointer HCVS-MgH{sub 2} desorbed hydrogen up to about 7.2 wt% and 7.1 wt%. - Abstract: This paper describes the hydriding chemical vapor synthesis (HCVS) of the hydrogen storage alloy MgH{sub 2} in a hydrogen atmosphere and the product's hydrogenation properties. Mg powder was used as a starting material to produce submicron MgH{sub 2} and uniformly heated to a temperature of 600 Degree-Sign C for Mg vaporization. The effects of deposited positions in HCVS reactor on the morphology and the composition of the obtained products were examined by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analyses. It is clearly seen that after the HCVS process, the particle size of synthesized MgH{sub 2} was drastically reduced to the sub-micron or micrometer-scale and these showed different shapes (needle-like nanofibers and angulated plate) depending on the deposited position. The hydrogen desorption temperatures of HCVS-MgH{sub 2} were measured using a differential scanning calorimeter (DSC). It was found that after the HCVS process, the desorption temperature of HCVS-MgH{sub 2} decreased from 430 to 385 Degree-Sign C and, simultaneously, the smallest particle size and the highest specific surface area were obtained. These observations indicate that the minimum hydrogen desorption temperature of HCVS-MgH{sub 2} powder with needle-like form can be obtained, and that this temperature is dependent on the particle size and the specific surface area of the products. The thermogravimetric

  16. Dielectric barrier discharge plasma atomizer for hydride generation atomic absorption spectrometry-Performance evaluation for selenium

    Science.gov (United States)

    Duben, Ondřej; Boušek, Jaroslav; Dědina, Jiří; Kratzer, Jan

    2015-09-01

    Atomization of selenium hydride in a quartz dielectric barrier discharge (DBD) atomizer was optimized and its performance was compared to that of the externally heated quartz multiatomizer. Argon was found as the best DBD discharge gas employing a flow rate of 75 ml min- 1 Ar while the DBD power was optimized at 14 W. The detection limits reached 0.24 ng ml- 1 Se in the DBD and 0.15 ng ml- 1 Se in the multiatomizer. The tolerance of DBD to interferences is even better than with the multiatomizer.

  17. Microstructural studies and crystallographic orientation of different zones and δ-hydrides in resistance welded Zircaloy-4 sheets

    Science.gov (United States)

    Kiran Kumar, N. A. P.; Szpunar, Jerzy. A.; He, Zhang

    2011-07-01

    The cold worked stress relieved (CWSR) Zircaloy-4 sheet used as endplate in nuclear fuel bundle is resistance welded with an endcap in argon environment. Later the welded sample is hydrided in a gaseous atmosphere at 400 °C. Optical microscopy (OM), electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) were used to examine the morphology and crystal orientation of the hydrides. The microstructural changes in different areas of the weld zone, heat affected zone (HAZ) and the as-received zone were analyzed using EBSD technique. Optical examination showed complete random morphological orientation of hydrides and predominantly basket-weave structure in the weld zone, with very few colonies of parallel plate structures. Variant selection for α-phase formation inside prior β-grains was identified at the weld centre. As we move from the weld centre to the as-received zone, the variant selection is found to be less probable. The δ-hydride platelets at the weld zone were always found to be growing perpendicular to the α-colonies having angular difference of 60-63° and follow (0 0 0 1) α-Zr//{1 1 1}δ-ZrH 1.5 orientation relationship with the zirconium matrix. Proposed description of complex distribution of hydrides and alloy microstructure at the weld and heat affected zone will contribute to a better understanding of mechanisms of failure of fuel cladding in various types of nuclear reactors.

  18. Kinetics of hydride front in Zircaloy-2 and H release from a fractional hydrided surface

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, M.; Gonzalez-Gonzalez, A.; Moya, J. S.; Remartinez, B.; Perez, S.; Sacedon, J. L. [Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain); Iberdrola, Tomas Redondo 3, 28033 Madrid (Spain); Instituto de Ciencia de Materiales de Madrid (CSIC), Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain)

    2009-07-15

    The authors study the hydriding process on commercial nuclear fuel claddings from their inner surface using an ultrahigh vacuum method. The method allows determining the incubation and failure times of the fuel claddings, as well as the dissipated energy and the partial pressure of the desorbed H{sub 2} from the outer surface of fuel claddings during the hydriding process. The correlation between the hydriding dissipated energy and the amount of zirconium hydride (formed at different stages of the hydriding process) leads to a near t{sup 1/2} potential law corresponding to the time scaling of the reaction for the majority of the tested samples. The calibrated relation between energy and hydride thickness allows one to calculate the enthalpy of the {delta}-ZrH{sub 1.5} phase. The measured H{sub 2} desorption from the external surface is in agreement with a proposed kinetic desorption model from the hydrides precipitated at the surface.

  19. Rietveld refinement of CdSe phases annealed under argon atmosphere

    Science.gov (United States)

    Mesquita, A. F.; Bernardes-Silva, A. C.; Porto, A. O.; de Lima, G. M.; de Miranda-Pinto, C. O. B.; Delgado, J. M.; de Chalbaud, L. M.; Lameiras, F. S.; Paniago, R.

    2005-10-01

    Hexagonal and cubic cadmium selenide were prepared from a chemical route by using cadmium chloride and potassium selenium hydride obtained from reaction of selenium powder and potassium boron hydride. The product obtained was thermally treated under argon flux at 300, 500 and 600 °C for 2 h and characterized by X-ray photoelectron spectroscopy and X-ray diffraction. The X-ray diffraction data were refined by Rietveld method and the structural parameters were determined for the phases of each annealed samples. At 300 °C five phases were identified: Cubic and hexagonal cadmium selenides and the contaminants: Potassium chloride, boron oxide and cadmium boron oxide. At 500 and 600 °C only the hexagonal cadmium selenide phase was identified besides the other above mentioned contaminant.

  20. Predicting formation enthalpies of metal hydrides

    DEFF Research Database (Denmark)

    Andreasen, A.

    2004-01-01

    In order for the hydrogen based society viz. a society in which hydrogen is the primary energy carrier to become realizable an efficient way of storing hydrogen is required. For this purpose metal hydrides are serious candidates. Metal hydrides are formedby chemical reaction between hydrogen and ...

  1. Submillimeter Spectroscopy of Hydride Molecules

    Science.gov (United States)

    Phillips, T. G.

    1998-05-01

    Simple hydride molecules are of great importance in astrophysics and astrochemistry. Physically they dominate the cooling of dense, warm phases of the ISM, such as the cores and disks of YSOs. Chemically they are often stable end points of chemical reactions, or may represent important intermediate stages of the reaction chains, which can be used to test the validity of the process. Through the efforts of astronomers, physicists, chemists, and laboratory spectroscopists we have an approximate knowledge of the abundance of some of the important species, but a great deal of new effort will be required to achieve the comprehensive and accurate data set needed to determine the energy balance and firmly establish the chemical pathways. Due to the low moment of inertia, the hydrides rotate rapidly and so have their fundamental spectral lines in the submillimeter. Depending on the cloud geometry and temperature profile they may be observed in emission or absorption. Species such as HCl, HF, OH, CH, CH(+) , NH_2, NH_3, H_2O, H_2S, H_3O(+) and even H_3(+) have been detected, but this is just a fraction of the available set. Also, most deduced abundances are not nearly sufficiently well known to draw definitive conclusions about the chemical processes. For example, the most important coolant for many regions, H_2O, has a possible range of deduced abundance of a factor of 1000. The very low submillimeter opacity at the South Pole site will be a significant factor in providing a new capabilty for interstellar hydride spectroscopy. The new species and lines made available in this way will be discussed.

  2. Fano factor in pure argon

    International Nuclear Information System (INIS)

    The Fano factor for 5.3 MeV alpha particles in pure argon has been measured with a gridded ionization chamber and estimated to be 0.20 (+0.01-0.02). The obtained value is consistent with the theoretical value if the contribution of elastic nuclear collisions to the Fano factor is taken into the consideration. There is no appreciable difference between the values for pure argon and for a gas mixture of Ar (10%)CH4 obtained in the previous measurement. (orig.)

  3. Hydrogen-storing hydride complexes

    Science.gov (United States)

    Srinivasan, Sesha S.; Niemann, Michael U.; Goswami, D. Yogi; Stefanakos, Elias K.

    2012-04-10

    A ternary hydrogen storage system having a constant stoichiometric molar ratio of LiNH.sub.2:MgH.sub.2:LiBH.sub.4 of 2:1:1. It was found that the incorporation of MgH.sub.2 particles of approximately 10 nm to 20 nm exhibit a lower initial hydrogen release temperature of 150.degree. C. Furthermore, it is observed that the particle size of LiBNH quaternary hydride has a significant effect on the hydrogen sorption concentration with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160.degree. C. and the other around 300.degree. C., with the main hydrogen release temperature reduced from 310.degree. C. to 270.degree. C., while hydrogen is first reversibly released at temperatures as low as 150.degree. C. with a total hydrogen capacity of 6 wt. % to 8 wt. %. Detailed thermal, capacity, structural and microstructural properties have been demonstrated and correlated with the activation energies of these materials.

  4. Activated aluminum hydride hydrogen storage compositions and uses thereof

    Science.gov (United States)

    Sandrock, Gary; Reilly, James; Graetz, Jason; Wegrzyn, James E.

    2010-11-23

    In one aspect, the invention relates to activated aluminum hydride hydrogen storage compositions containing aluminum hydride in the presence of, or absence of, hydrogen desorption stimulants. The invention particularly relates to such compositions having one or more hydrogen desorption stimulants selected from metal hydrides and metal aluminum hydrides. In another aspect, the invention relates to methods for generating hydrogen from such hydrogen storage compositions.

  5. Noble-gas hydrides: new chemistry at low temperatures.

    Science.gov (United States)

    Khriachtchev, Leonid; Räsänen, Markku; Gerber, R Benny

    2009-01-20

    Noble-gas chemistry has been undergoing a renaissance in recent years, due in large part to noble-gas hydrides, HNgY, where Ng = noble-gas atom and Y = electronegative fragment. These molecules are exceptional because of their relatively weak bonding and large dipole moments, which lead to strongly enhanced effects of the environment, complexation, and reactions. In this Account, we discuss the matrix-isolation synthesis of noble-gas hydrides, their spectroscopic and structural properties, and their stabilities.This family of species was discovered in 1995 and now has 23 members that are prepared in noble-gas matrices (HXeBr, HKrCl, HXeH, HXeOH, HXeO, etc.). The preparations of the first neutral argon molecule, HArF, and halogen-free organic noble-gas molecules (HXeCCH, HXeCC, HKrCCH, etc.) are important highlights of the field. These molecules are formed by the neutral H + Ng + Y channel. The first addition reaction involving HNgY molecules was HXeCC + Xe + H --> HXeCCXeH, and this led to the first hydride with two noble-gas atoms (recently extended by HXeOXeH). The experimental synthesis of HNgY molecules starts with production of H and Y fragments in solid noble gas via the UV photolysis of suitable precursors. The HNgY molecules mainly form upon thermal mobilization of the fragments.One of the unusual properties of these molecules is the hindered rotation of some HNgY molecules in solid matrices; this has been theoretically modeled. HNgY molecules also have unusual solvation effects, and the H-Xe stretching mode shifts to higher frequencies (up to about 150 cm-1) upon interaction with other species.The noble hydrides have a new bonding motif: HNgY molecules can be represented in the form (H-Ng)+Y-, where (H-Ng)+ is mainly covalent, whereas the interaction between (HNg)+ and Y- is predominantly ionic. The HNgY molecules are highly metastable species representing high-energy materials. The decomposition process HNgY --> Ng + HY is always strongly exoergic

  6. Experimental reproducibility analysis in DU hydriding

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Daeseo; Park, Jongcheol; Chung, Hongsuk [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    A storage and delivery system (SDS) is used for storing hydrogen isotopes as a metal hydride form. The rapid hydriding of tritium is very important not only for safety reasons but also for the economic design and operation of the SDS. For the storage, supply, and recovery of hydrogen isotopes, depleted uranium (DU) has been extensively proposed. To develop nuclear fusion technology, it will be necessary to store and supply hydrogen isotopes needed for Tokamak operation. The experimental reproducibility of bed temperature on DU hydriding was also analyzed. The experimental reproducibility of apparatus was acceptable for all the experiments. The experimental reproducibility of tank pressure on DU hydriding was analyzed. As the hydriding performs, the tank pressure showed decreasing trend. The experimental reproducibility of bed temperature on DU hydriding was also analyzed. As the hydriding performs, the bed temperatures increased up to maximum temperature with exothermic reaction and then they showed decreasing trend. The experimental reproducibility of apparatus was acceptable for all the experiments.

  7. Hydrogen adsorption on palladium and palladium hydride at 1 bar

    DEFF Research Database (Denmark)

    Johansson, Martin; Skulason, Egill; Nielsen, Gunver;

    2010-01-01

    strongly to Pd hydride than to Pd. The activation barrier for desorption at a H coverage of one mono layer is slightly lower on Pd hydride, whereas the activation energy for adsorption is similar on Pd and Pd hydride. It is concluded that the higher sticking probability on Pd hydride is most likely caused...... by a slightly lower equilibrium coverage of H, which is a consequence of the lower heat of adsorption for H on Pd hydride....

  8. Hydride heat pump with heat regenerator

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative hydride heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system. A series of at least four canisters containing a lower temperature performing hydride and a series of at least four canisters containing a higher temperature performing hydride is provided. Each canister contains a heat conductive passageway through which a heat transfer fluid is circulated so that sensible heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  9. Organic solvents as interferents in arsenic determination by hydride generation atomic absorption spectrometry with flame atomization

    Science.gov (United States)

    Karadjova, Irina B.; Lampugnani, Leonardo; Dědina, Jiri; D'Ulivo, Alessandro; Onor, Massimo; Tsalev, Dimiter L.

    2006-05-01

    Interference effects of various organic solvents miscible with water on arsenic determination by hydride generation atomic absorption spectrometry have been studied. Arsine was chemically generated in continuous flow hydride generation system and atomized by using a flame atomizer able to operate in two modes: miniature diffusion flame and flame-in-flame. The effects of experimental variables and atomization mode were investigated: tetrahydroborate and hydrochloric acid concentrations, argon, hydrogen and oxygen supply rates for the microflame, and the distance from the atomization region to the observation zone. The nature of the species formed in the flame due to the pyrolysis of organic solvent vapors entering the flame volume together with arsine is discussed. The observed signal depression in the presence of organic solvents has been mainly attributed to the atomization interference due to heterogeneous gas-solid reaction between the free arsenic atoms and finely dispersed carbon particles formed by carbon radicals recombination. The best tolerance to interferences was obtained by using flame-in-flame atomization (5-10 ml min - 1 of oxygen flow rate), together with higher argon and hydrogen supply rates and elevated observation heights.

  10. Attainable superheat of argon-helium, argon-neon solutions.

    Science.gov (United States)

    Baidakov, Vladimir G; Kaverin, Aleksey M; Andbaeva, Valentina N

    2008-10-16

    The method of lifetime measurement has been used to investigate the kinetics of spontaneous boiling-up of superheated argon-helium and argon-neon solutions. Experiments were made at a pressure of p = 1.5 MPa and concentrations up to 0.33 mol% in the range of nucleation rates from 10 (4) to 10 (8) s (-1) m (-3). The homogeneous nucleation regime has been distinguished. With good agreement between experimental data and homogeneous nucleation theory in temperature and concentration dependences of the nucleation rate, a systematic underestimation by 0.25-0.34 K has been revealed in superheat temperatures over the saturated line attained by experiment as compared with theoretical values calculated in a macroscopic approximation. The revealed disagreement between theory and experiment is connected with the dependence of the properties of new-phase nuclei on their size.

  11. Geoneutrino and Hydridic Earth model. Version 2

    OpenAIRE

    Bezrukov, Leonid

    2013-01-01

    Uranium, Thorium and Potassium-40 abundances in the Earth were calculated in the frame of Hydridic Earth model. Terrestrial heat producton from U, Th and K40 decays was calculated also. We must admit the existance of Earth expansion process to understand the obtained large value of terrestrial heat producton. The geoneutrino detector with volume more than 5 kT (LENA type) must be constructed to definitely separate between Bulk Silicat Earth model and Hydridic Earth model. In second version of...

  12. Atomistic Potentials for Palladium-Silver Hydrides

    OpenAIRE

    Hale, L. M.; Wong, B. M.; Zimmerman, J. A.; Zhou, X.

    2013-01-01

    New EAM potentials for the ternary palladium-silver-hydrogen system are developed by extending a previously developed palladium-hydrogen potential. The ternary potentials accurately capture the heat of mixing and structural properties associated with solid solution alloys of palladium-silver. Stable hydrides are produced with properties that smoothly transition across the compositions. Additions of silver to palladium are predicted to alter the properties of the hydrides by decreasing the mis...

  13. Probing the cerium/cerium hydride interface using nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Brierley, Martin, E-mail: martin.brierley@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire RG7 4PR (United Kingdom); University of Manchester, Manchester M13 9PL (United Kingdom); Knowles, John, E-mail: john.knowles@awe.co.uk [Atomic Weapons Establishment, Aldermaston, Berkshire RG7 4PR (United Kingdom)

    2015-10-05

    Highlights: • A disparity exists between the minimum energy and actual shape of a cerium hydride. • Cerium hydride is found to be harder than cerium metal by a ratio of 1.7:1. • A zone of material under compressive stress was identified surrounding the hydride. • No distribution of hardness was apparent within the hydride. - Abstract: A cerium hydride site was sectioned and the mechanical properties of the exposed phases (cerium metal, cerium hydride, oxidised cerium hydride) were measured using nanoindentation. An interfacial region under compressive stress was observed in the cerium metal surrounding a surface hydride that formed as a consequence of strain energy generated by the volume expansion associated with precipitation of the hydride phase.

  14. Probing the cerium/cerium hydride interface using nanoindentation

    International Nuclear Information System (INIS)

    Highlights: • A disparity exists between the minimum energy and actual shape of a cerium hydride. • Cerium hydride is found to be harder than cerium metal by a ratio of 1.7:1. • A zone of material under compressive stress was identified surrounding the hydride. • No distribution of hardness was apparent within the hydride. - Abstract: A cerium hydride site was sectioned and the mechanical properties of the exposed phases (cerium metal, cerium hydride, oxidised cerium hydride) were measured using nanoindentation. An interfacial region under compressive stress was observed in the cerium metal surrounding a surface hydride that formed as a consequence of strain energy generated by the volume expansion associated with precipitation of the hydride phase

  15. Binocular indirect argon laser photocoagulator.

    OpenAIRE

    Mizuno, K

    1981-01-01

    The binocular indirect argon laser photocoagulator was newly designed to enable visualisation of the entire fundus during panretinal laser photocoagulation and to treat retinal tears immediately after buckling procedures of the sclera. The lamp housing of the binocular ophthalmoscope was remodelled and adjusted so that the laser beam and illuminating light are coaxial after leaving the ophthalmoscope. The blocking filter was permanently fixed in the eye-pieces to lighten the weight of the oph...

  16. Liquid Argon Barrel Cryostat Arrived

    CERN Multimedia

    Pailler, P

    Last week the first of three cryostats for the ATLAS liquid argon calorimeter arrived at CERN. It had travelled for 46 days over several thousand kilometers from Japan to CERN. During three years it has been fabricated by Kawasaki Heavy Industries Ltd. at Harima, close to Kobe, under contract from Brookhaven National Laboratory (BNL) of the U.S.. This cryostat consists of two concentric cylinders made of aluminium: the outer vacuum vessel with a diameter of 5.5 m and a length of 7 m, and the inner cold vessel which will contain the electromagnetic barrel calorimeter immersed in liquid argon. The total weight will be 270 tons including the detectors and the liquid argon. The cryostat is now located in building 180 where it will be equipped with 64 feed-throughs which serve for the passage of 122,880 electrical lines which will carry the signals of the calorimeter. After integration of the calorimeter, the solenoidal magnet of ATLAS will be integrated in the vacuum vessel. A final cold test of the cryostat inc...

  17. gamma-Zr-Hydride Precipitate in Irradiated Massive delta- Zr-Hydride

    DEFF Research Database (Denmark)

    Warren, M. R.; Bhattacharya, D. K.

    1975-01-01

    During examination of A Zircaloy-2-clad fuel pin, which had been part of a test fuel assembly in a boiling water reactor, several regions of severe internal hydriding were noticed in the upper-plenum end of the pin. Examination of similar fuel pins has shown that hydride of this type is caused...

  18. The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components Delayed Hydride Cracking

    CERN Document Server

    Puls, Manfred P

    2012-01-01

    By drawing together the current theoretical and experimental understanding of the phenomena of delayed hydride cracking (DHC) in zirconium alloys, The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components: Delayed Hydride Cracking provides a detailed explanation focusing on the properties of hydrogen and hydrides in these alloys. Whilst the focus lies on zirconium alloys, the combination of both the empirical and mechanistic approaches creates a solid understanding that can also be applied to other hydride forming metals.   This up-to-date reference focuses on documented research surrounding DHC, including current methodologies for design and assessment of the results of periodic in-service inspections of pressure tubes in nuclear reactors. Emphasis is placed on showing that our understanding of DHC is supported by progress across a broad range of fields. These include hysteresis associated with first-order phase transformations; phase relationships in coherent crystalline metallic...

  19. Composing Experimental Environment of PRIDE Argon cell

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Seonho; Jang, Yongkuk; Cho, Il Je [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    In PRIDE depleted Uranium feed material and a depleted Uranium mixed with some surrogate material are used for performing engineering scale Pyroprocessing. PRIDE has to maintain inert atmosphere because of the characteristic of Electrolytic Reduction technology, Electro refining technology, Electrowinning technology. The impurity concentration of the Argon cell has to be under 50 ppm(Oxygen, moisture). Atmospheric pressure changes and temperature changes can affect the Argon cell's impurity concentration. In this paper, how to compose the Argon cell impurity concentration under 50 ppm to make the exact optimal experimental environment(Oxygen, moisture) will be introduced. Composing the exact optimal experimental environment by supplying Argon gas have been introduced in this paper. Continuously supplying Argon gas which is heavier than the Oxygen through the bottom of the Argon cell the oxygen eventually discharged through the high vent fan and lower the impurity concentration of Oxygen.

  20. A Study on the Radial Hydride Assisted Delayed Hydride Cracking of Zircaloy

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jin-Ho; Lee, Ji-Min; Kim, Yong-Soo [Hanyang University, Seoul (Korea, Republic of)

    2015-05-15

    Extensive studies have been done on understanding of DHC(Delayed hydride cracking) phenomenon since several zirconium alloy pressure tubes failed in nuclear reactor in the 1970s. Recently, long-term dry storage strategy has been considered seriously in order to manage spent nuclear fuel in Korea and other countries around the world. Consequentially, many researches have been investigated the degradation mechanisms which will threaten the spent fuel integrity during dry storage and showed that hydrogen related phenomenon such as hydride reorientation and DHC are the critical factors. Especially, DHC is the direct cracking mechanism which can cause not only a through-wall defect but also a radiation leak to the environment. In addition, DHC can be enhanced by radial hydride as reported by Kim who demonstrate that radial hydrides clearly act as crack linkage path. This phenomenon is known as the radial hydride assisted DHC (RHA-DHC). Therefore, study on DHC is essential to ensure the safety of spent fuel. Finite element analysis will be carried out for the stress gradient evaluation around notch tip. A variation in thermal cycle which leads to change in hydrogen solid solution trajectory may be required. If the radial hydride precipitates at notch tip, we will investigate what conditions should be met. Ultimately, we will suggest the regulation criteria for long-term dry storage of spent nuclear fuel.

  1. Computational study of metal hydride cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Satheesh, A.; Muthukumar, P.; Dewan, Anupam [Department of Mechanical Engineering, Indian Institute of Technology, Guwahati, Guwahati 781039 (India)

    2009-04-15

    A computational study of a metal hydride cooling system working with MmNi{sub 4.6}Al{sub 0.4}/MmNi{sub 4.6}Fe{sub 0.4} hydride pair is presented. The unsteady, two-dimensional mathematical model in an annular cylindrical configuration is solved numerically for predicting the time dependent conjugate heat and mass transfer characteristics between coupled reactors. The system of equations is solved by the fully implicit finite volume method (FVM). The effects of constant and variable wall temperature boundary conditions on the reaction bed temperature distribution, hydrogen concentration, and equilibrium pressures of the reactors are investigated. A dynamic correlation of the pressure-concentration-temperature plot is presented. At the given operating temperatures of 363/298/278 K (T{sub H}/T{sub M}/T{sub C}), the cycle time for the constant and variable wall temperature boundary conditions of a single-stage and single-effect metal hydride system are found to be 1470.0 s and 1765.6 s, respectively. The computational results are compared with the experimental data reported in the literature for LaNi{sub 4.61}Mn{sub 0.26}Al{sub 0.13}/La{sub 0.6}Y{sub 0.4}Ni{sub 4.8}Mn{sub 0.2} hydride pair and a good agreement between the two was observed. (author)

  2. The electrochemical impedance of metal hydride electrodes

    DEFF Research Database (Denmark)

    Valøen, Lars Ole; Lasia, Andrzej; Jensen, Jens Oluf;

    2002-01-01

    The electrochemical impedance responses for different laboratory type metal hydride electrodes were successfully modeled and fitted to experimental data for AB5 type hydrogen storage alloys as well as one MgNi type electrode. The models fitted the experimental data remarkably well. Several AC equ...

  3. Dielectric barrier discharge plasma atomizer for hydride generation atomic absorption spectrometry—Performance evaluation for selenium

    International Nuclear Information System (INIS)

    Atomization of selenium hydride in a quartz dielectric barrier discharge (DBD) atomizer was optimized and its performance was compared to that of the externally heated quartz multiatomizer. Argon was found as the best DBD discharge gas employing a flow rate of 75 ml min−1 Ar while the DBD power was optimized at 14 W. The detection limits reached 0.24 ng ml−1 Se in the DBD and 0.15 ng ml−1 Se in the multiatomizer. The tolerance of DBD to interferences is even better than with the multiatomizer. - Highlights: • SeH2 atomization in a dielectric barrier discharge (DBD) was optimized for AAS. • Atomizer performance was compared for DBD and externally heated quartz atomizer. • Detection limits were quantified and interferences were studied in both atomizers. • Atomization efficiency in the DBD was estimated

  4. RF sputtering for controlling dihydride and monohydride bond densities in amorphous silicon hydride

    Science.gov (United States)

    Jeffery, F.R.; Shanks, H.R.

    1980-08-26

    A process is described for controlling the dihydride and monohydride bond densities in hydrogenated amorphous silicone produced by reactive rf sputtering of an amorphous silicon target. There is provided a chamber with an amorphous silicon target and a substrate therein with the substrate and the target positioned such that when rf power is applied to the target the substrate is in contact with the sputtering plasma produced thereby. Hydrogen and argon are fed to the chamber and the pressure is reduced in the chamber to a value sufficient to maintain a sputtering plasma therein, and then rf power is applied to the silicon target to provide a power density in the range of from about 7 watts per square inch to about 22 watts per square inch to sputter an amorphous solicone hydride onto the substrate, the dihydride bond density decreasing with an increase in the rf power density. Substantially pure monohydride films may be produced.

  5. Dielectric barrier discharge plasma atomizer for hydride generation atomic absorption spectrometry—Performance evaluation for selenium

    Energy Technology Data Exchange (ETDEWEB)

    Duben, Ondřej [Institute of Analytical Chemistry of the CAS, v.v.i., Veveří 97, CZ-602 00 Brno (Czech Republic); Faculty of Science, Department of Analytical Chemistry, Charles University in Prague, Hlavova 8, Prague, CZ 128 43 Czech Republic (Czech Republic); Boušek, Jaroslav [Faculty of Electrical Engineering and Communications, Brno University of Technology, Technická 1058/10, 61600 Brno (Czech Republic); Dědina, Jiří [Institute of Analytical Chemistry of the CAS, v.v.i., Veveří 97, CZ-602 00 Brno (Czech Republic); Kratzer, Jan, E-mail: jkratzer@biomed.cas.cz [Institute of Analytical Chemistry of the CAS, v.v.i., Veveří 97, CZ-602 00 Brno (Czech Republic)

    2015-09-01

    Atomization of selenium hydride in a quartz dielectric barrier discharge (DBD) atomizer was optimized and its performance was compared to that of the externally heated quartz multiatomizer. Argon was found as the best DBD discharge gas employing a flow rate of 75 ml min{sup −1} Ar while the DBD power was optimized at 14 W. The detection limits reached 0.24 ng ml{sup −1} Se in the DBD and 0.15 ng ml{sup −1} Se in the multiatomizer. The tolerance of DBD to interferences is even better than with the multiatomizer. - Highlights: • SeH{sub 2} atomization in a dielectric barrier discharge (DBD) was optimized for AAS. • Atomizer performance was compared for DBD and externally heated quartz atomizer. • Detection limits were quantified and interferences were studied in both atomizers. • Atomization efficiency in the DBD was estimated.

  6. Transition probabilities for argon I

    International Nuclear Information System (INIS)

    Transition probabilities for ArI lines have been calculated on the basis of the (j,k)-coupling scheme for more than 16000 spectral lines belonging to the transition arrays 4s-np (n=4 to n=9), 5s-np (n=5 to n=9), 6s-np (n=6 to n=9), 7s-np (n=8 to n=9), 4p-ns (n=5 to n=10), 5p-ns (n=6 to n=9), 6p-ns (n=7 to n=8), 4p-nd (n=3 to n=9), 5p-nd (n=4 to n=9), 3d-np (n=5 to n=9), 4d-np (n=6 to n=9), 5d-np (n=7 to n=9), 3d-nf (n=4 to n=9), 4d-nf (n=4 to n=9), 5d-nf (n=5 to n=9), 4f-nd (n=5 to n=9) 5f-nd (n=6 to n=9), 4f-ng (n=5 to n=9), 5f-ng (n=6 to n=9). Inso far as values by other authors exist, comparison is made with these values. It turns out that the results obtained in (j,k)-coupling are close to those obtained in intermediate coupling except for intercombination lines. For high principal and/or orbital quantum numbers the transition probabilities for a multiplet approach those of the corresponding transitions in atomic hydrogen. The calculated values are applied to construct a simplified argon-atom model, which reflects the real transition properties and which allows simplified but realistic non-equilibrium calculations for argon plasmas which deviate from local thermodynamic equilibrium (LTE)

  7. Determination of arsenic and selenium by hydride generation and headspace solid phase microextraction coupled with optical emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Tyburska, Anna; Jankowski, Krzysztof, E-mail: kj@ch.pw.edu.pl; Rodzik, Agnieszka

    2011-07-15

    A hydride generation headspace solid phase microextraction technique has been developed in combination with optical emission spectrometry for determination of total arsenic and selenium. Hydrides were generated in a 10 mL volume septum-sealed vial and subsequently collected onto a polydimethylsiloxane/Carboxen solid phase microextraction fiber from the headspace of sample solution. After completion of the sorption, the fiber was transferred into a thermal desorption unit and the analytes were vaporized and directly introduced into argon inductively coupled plasma or helium microwave induced plasma radiation source. Experimental conditions of hydride formation reaction as well as sorption and desorption of analytes have been optimized showing the significant effect of the type of the solid phase microextraction fiber coating, the sorption time and hydrochloric acid concentration of the sample solution on analytical characteristics of the method developed. The limits of detection of arsenic and selenium were 0.1 and 0.8 ng mL{sup -1}, respectively. The limit of detection of selenium could be improved further using biosorption with baker's yeast Saccharomyces cerevisiae for analyte preconcentration. The technique was applied for the determination of total As and Se in real samples.

  8. Opacity of Shock-Generated Argon Plasmas

    Institute of Scientific and Technical Information of China (English)

    王藩侯; 陈敬平; 周显明; 李西军; 经福谦; 孟续军; 孙永盛

    2001-01-01

    Argon plasmas with uniform density and temperature are generated by a planar shock wave through argon gas. The opacities of argon plasma, covering the thermodynamic states at temperatures of 1.4-2.2eV and in densities of 0.0083- 0.015 g/cm3, are investigated by measuring the emitted radiance versus time at several visible wavelengths. Comparison of the measured opacities with those calculated demonstrates that the average atom model can be used well to describe the essential transport behaviour of photons in argon plasma under the abovementioned thermodynamic condition. A simplified and self-consistent method to deduce the reflectivity R(λ) at the baseplate surface is applied. It demonstrates that the values of R(λ) are all around 0.4 in the experiments, which are basically in agreement with those given by Erskine previously (1994 J. Quant. Spectrosc. Radiat.Transfer 51 97).

  9. Status and perspecitves of liquid argon calorimeters

    International Nuclear Information System (INIS)

    The status of liquid argon calorimeters is reviewed, and experience obtained with these devices is described. Future perspectives of the liquid ionization chamber technique in calorimetry are also discussed. (orig.)

  10. Clinical periodontics with the argon laser

    Science.gov (United States)

    Finkbeiner, R. L.

    1995-04-01

    The argon laser has proven to be a valuable tool for the thermodynamic debridement of the periodontal lesion, incisions and tissue fusion. Illustrations of clinical applications and discussion of laser parameters will be provided.

  11. Hydrogen storage in metallic hydrides: the hydrides of magnesium-nickel alloys

    International Nuclear Information System (INIS)

    The massive and common use of hydrogen as an energy carrier requires an adequate solution to the problem of storing it. High pressure or low temperatures are not entirely satisfactory, having each a limited range of applications. Reversible metal hydrides cover a range of applications intermediate to high pressure gas and low temperature liquid hydrogen, retaining very favorable safety and energy density characteristics, both for mobile and stationary applications. This work demonstrates the technical viability of storing hydrogen in metal hydrides of magnesium-nickel alloys. Also, it shows that technology, a product of science, can be generated within an academic environment, of the goal is clear, the demand outstanding and the means available. We review briefly theoretical models relating to metal hydride properties, specially the thermodynamics properties relevant to this work. We report our experimental results on hydrides of magnesium-nickel alloys of various compositions including data on structure, hydrogen storage capacities, reaction kinetics, pressure-composition isotherms. We selected a promising alloy for mass production, built and tested a modular storage tank based on the hydrides of the alloy, with a capacity for storing 10 Nm sup(3) of hydrogen of 1 atm and 20 sup(0)C. The tank weighs 46,3 Kg and has a volume of 21 l. (author)

  12. Argon plasma irradiation of polypropylene

    Energy Technology Data Exchange (ETDEWEB)

    Slepicka, P., E-mail: petr.slepicka@vscht.c [Department of Solid State Engineering, Institute of Chemical Technology, 16628 Prague (Czech Republic); Vasina, A. [Department of Solid State Engineering, Institute of Chemical Technology, 16628 Prague (Czech Republic); Kolska, Z. [J.E. Purkyne University, Department of Chemistry, 40096 Usti Nad Labem (Czech Republic); Luxbacher, T. [Anton Paar GmbH, 8054 Graz (Austria); Malinsky, P.; Mackova, A. [Nuclear Physics Institute of Academy of Sciences of the Czech Republic, 25068 Rez (Czech Republic); Svorcik, V. [Department of Solid State Engineering, Institute of Chemical Technology, 16628 Prague (Czech Republic)

    2010-06-15

    Polypropylene samples were exposed to argon plasma discharge and the changes of the PP surface properties were studied by different methods. Surface wettability was derived from contact angle measured by standard goniometry and chemical structure of the plasma modified PP was studied using X-ray photoelectron spectroscopy (XPS) and by Rutherford backscattering spectroscopy (RBS), surface morphology and roughness of samples using AFM. Zeta potential of pristine and modified PP was determined with the SurPASS. The presence of incorporated oxygen in the PP surface layer, about 60 nm thick, was observed in RBS spectra. Oxygen concentration is a decreasing function of the depth. With progressing aging time the oxygen concentration on the PP surface decreases. Plasma treatment results in a rapid decrease of the contact angle, which increases again with increasing aging time. In XPS measurement the oxygen containing structures, created by the plasma treatment, were found on the very surface of the modified PP and the zeta potential being changed too. The significant difference in zeta potential between pristine and plasma treated PP clearly indicates that the plasma treatment leads to a more hydrophilic PP surface.

  13. Negative corona current pulses in argon and in mixture argon with SF6

    International Nuclear Information System (INIS)

    Waveforms of the first negative current pulses in a short negative point-to plane gap in pure argon and argon with SF6 admixture have been investigated with a nanosecond time resolution at a gas pressure 50 kPa as a function of applied gap voltage and content of SF6 in the mixture. We have made an attempt to explain the differences in the discharge development in pure argon and in argon with admixture of SF6 based on the observed changes of the pulse shape. The experimental results obtained will be discussed in context with existing computer simulation models (Authors)

  14. Measurements on scintillation light from liquid argon

    International Nuclear Information System (INIS)

    It is shown that an argon calorimeter can operate as a scintillation detector, provided that xenon is added. With the addition of 170 ppm xenon a light yield of 70% has been obtained. In addition the light yield is determined under influence of an electric field, from differently ionising particles and by the use of aluminium mirrors acting as light guides. Finally first measurements with a photomultiplier working at liquid argon temperatures are reported. (orig.)

  15. Argon Laser Photoablation for Postburn Conjunctival Pigmentation

    Directory of Open Access Journals (Sweden)

    Seong Joon Ahn

    2014-01-01

    Full Text Available We report a case of an ocular burn injury from boiling water which resulted in conjunctival pigmentation, 1 week following injury. For cosmetic purposes, 2 sessions of argon laser photoablation were performed. One month after laser treatment, conjunctival pigmentation had been successfully removed and the patient was very satisfied with the results. Argon laser photoablation may be an effective way to remove postburn conjunctival pigmentation.

  16. SANS Measurement of Hydrides in Uranium

    International Nuclear Information System (INIS)

    SANS scattering is shown to be an effective method for detecting the presence of hydrogen precipitates in uranium. High purity polycrystalline samples of depleted uranium were given several hydriding treatments which included extended exposures to hydrogen gas at two different pressures at 630 C as well as a furnace anneal at 850 C followed by slow cooling in the near absence hydrogen gas. All samples exhibited neutron scattering that was in proportion to the expected levels of hydrogen content. While the scattering signal was strong, the shape of the scattering curve indicated that the scattering objects were large sized objects. Only by use of a very high angular resolution SANS technique was it possible to make estimates of the major diameter of the scattering objects. This analysis permits an estimate of the volume fraction and means size of the hydride precipitates in uranium

  17. Metal hydrides based high energy density thermal battery

    International Nuclear Information System (INIS)

    Highlights: • The principle of the thermal battery using advanced metal hydrides was demonstrated. • The thermal battery used MgH2 and TiMnV as a working pair. • High energy density can be achieved by the use of MgH2 to store thermal energy. - Abstract: A concept of thermal battery based on advanced metal hydrides was studied for heating and cooling of cabins in electric vehicles. The system utilized a pair of thermodynamically matched metal hydrides as energy storage media. The pair of hydrides that was identified and developed was: (1) catalyzed MgH2 as the high temperature hydride material, due to its high energy density and enhanced kinetics; and (2) TiV0.62Mn1.5 alloy as the matching low temperature hydride. Further, a proof-of-concept prototype was built and tested, demonstrating the potential of the system as HVAC for transportation vehicles

  18. Argon clusters embedded in helium nanodroplets.

    Science.gov (United States)

    da Silva, Filipe Ferreira; Bartl, Peter; Denifl, Stephan; Echt, Olof; Märk, Tilmann D; Scheier, Paul

    2009-11-14

    Electron impact ionization of argon clusters embedded in helium droplets is investigated. Superior mass resolution makes it possible to distinguish between nominally isobaric cluster ions. An abundance maximum for ArHe(12)(+) is unambiguously confirmed; the spectra also prove the formation of Ar(2)He(n)(+) complexes that had been claimed to fragment into pure Ar(2)(+). Distributions of larger argon cluster ions containing up to 60 atoms closely resemble distributions observed upon electron impact or photoionization of bare argon clusters; caging and evaporative cooling provided by the helium matrix do not suffice to quench fragmentation of the nascent argon cluster ions. Intriguing abundance anomalies are observed in distributions of argon cluster ions that contain water, nitrogen or oxygen impurities. The strong abundance of Ar(55)H(2)O(+), Ar(54)O(2)(+) and Ar(54)N(2)(+) contrasts with the virtual absence of slightly larger cluster ions containing the corresponding impurities. The features are probably related to enhanced cluster ion stability upon closure of the second icosahedral shell but the difference in magic numbers (54 versus 55) and the well-known reactivity of charged argon-nitrogen complexes suggest structural differences. PMID:19851558

  19. Potassium-argon/argon-40-argon-39 geochronology of Cenozoic alkali basalts from the South China Sea

    Institute of Scientific and Technical Information of China (English)

    YAN Quanshu; SHI Xuefa; YANG Yaomin; WANG Kunshan

    2008-01-01

    Based on the isotopic chronologic results of Cenozoic alkali basalts from the South China Sea,the characteristics of volcanic activi-ty of the South China Sea after spreading were studied.The potassium - argon ages of eight alkali basalt samples from the South China Sea,and the argon - argon ages of two samples among them are reported.Apparent ages of the whole rock are 3.80 to 7.91 Ma with an average value of 5.43 Ma (potassium- argon,whole rock),and there is little difference among samples at the same location,e.g.,4.76~5.78 Ma for location S04-12.The argon - argon ages for the two samples are 6.06 and 4.71 Ma,which lie within the age scope of potassium - argon method.The dating results indicate that rock-forming age is from late Miocene to Pli-ocene,which is consistent with erupting event for alkali basalts from adjacent regions of the South China Sea.Volcanic activities occur after the cessation of spreading of the South China Sea,which are controlled by lithospheric fault and the spreading center formed during the spreading period of the South China Sea.These dating results,combined with geochemical characteristics of these basalts,the published chronological data for the South China Sea and its adjacent regions,and the updated geophysical data near Hainan Island,suggest that after the cessation of spreading of the South China Sea,there occur widely distributing magmatic activities which primarily is alkali basalt,and the volcanic activity continues to Quaternary.The activity may be relative to Hainan mantle plume originated from core/mantle boundary.

  20. METHOD AND APPARATUS FOR MAKING URANIUM-HYDRIDE COMPACTS

    Science.gov (United States)

    Wellborn, W.; Armstrong, J.R.

    1959-03-10

    A method and apparatus are presented for making compacts of pyrophoric hydrides in a continuous operation out of contact with air. It is particularly useful for the preparation of a canned compact of uranium hydride possessing high density and purity. The metallic uranium is enclosed in a container, positioned in a die body evacuated and nvert the uranium to the hydride is admitted and the container sealed. Heat is applied to bring about the formation of the hydride, following which compression is used to form the compact sealed in a container ready for use.

  1. Quantification of water and plasma diagnosis for electrothermal vaporization-inductively coupled plasma-mass spectrometry: the use of argon and argide polyatomics as probing species

    International Nuclear Information System (INIS)

    The water content of the carrier flow originating from an electrothermal vaporization unit (ETV) attached to an inductively coupled plasma mass spectrometer was monitored by following the argon hydride ion (ArH+) at m/z=37. The goal was to measure the water expelled by the ETV at sample vaporization and evaluate the influence of this parameter on the ion-generation efficiency. Linear responses from the argon hydride were obtained when the water loading in the plasma injector flow was increased from 0 to 3.3 mg/min. Other argides and water-derived species (Ar+, Ar+2 and O+2) were also monitored simultaneously and the effects from operating parameters have been calculated for each species. The magnitude of these effects can eventually be used as diagnosis tools. It was also found that signals for zinc, copper, lead, antimony and arsenic were greatly influenced by slight variations in water loading at low water levels. These signal fluctuations are greatly attenuated and transients' shapes restored by convoluting each element transient with the ArH+ or Ar+2 curves that were recorded simultaneously. Envisioned applications that would benefit from a water-enhanced signal include spray electrothermal vaporization, direct sample insertion and laser ablation for inductively coupled plasma-mass spectrometry. The argon dimer Ar+2 seems more appropriate for making the correction since it provides a direct insight on the plasma temperature and provides a robust signal. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  2. Argon Collection And Purification For Proliferation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Achey, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hunter, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-09

    In order to determine whether a seismic event was a declared/undeclared underground nuclear weapon test, environmental samples must be taken and analyzed for signatures that are unique to a nuclear explosion. These signatures are either particles or gases. Particle samples are routinely taken and analyzed under the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) verification regime as well as by individual countries. Gas samples are analyzed for signature gases, especially radioactive xenon. Underground nuclear tests also produce radioactive argon, but that signature is not well monitored. A radioactive argon signature, along with other signatures, can more conclusively determine whether an event was a nuclear test. This project has developed capabilities for collecting and purifying argon samples for ultra-low-background proportional counting. SRNL has developed a continuous gas enrichment system that produces an output stream containing 97% argon from whole air using adsorbent separation technology (the flow diagram for the system is shown in the figure). The vacuum swing adsorption (VSA) enrichment system is easily scalable to produce ten liters or more of 97% argon within twelve hours. A gas chromatographic separation using a column of modified hydrogen mordenite molecular sieve has been developed that can further purify the sample to better than 99% purity after separation from the helium carrier gas. The combination of these concentration and purification systems has the capability of being used for a field-deployable system for collecting argon samples suitable for ultra-low-background proportional counting for detecting nuclear detonations under the On-Site Inspection program of the CTBTO verification regime. The technology also has applications for the bulk argon separation from air for industrial purposes such as the semi-conductor industry.

  3. Attenuation of vacuum ultraviolet light in liquid argon

    CERN Document Server

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

    2015-01-01

    The transmission of liquid argon has been measured, wavelength resolved, for a wavelength interval from 118 to 250 nm. The wavelength dependent attenuation length is presented for pure argon. It is shown that no universal wavelength independent attenuation length can be assigned to liquid argon for its own fluorescence light due to the interplay between the wavelength dependent emission and absorption. A decreasing transmission is observed below 130 nm in both chemically cleaned and distilled liquid argon and assigned to absorption by the analogue of the first argon excimer continuum. For not perfectly cleaned argon a strong influence of impurities on the transmission is observed. Two strong absorption bands at 126.5 and 141.0 nm with approximately 2 and 4 nm width, respectively, are assigned to traces of xenon in argon. A broad absorption region below 180 nm is found for unpurified argon and tentatively attributed to the presence of water in the argon sample.

  4. High energy density battery based on complex hydrides

    Science.gov (United States)

    Zidan, Ragaiy

    2016-04-26

    A battery and process of operating a battery system is provided using high hydrogen capacity complex hydrides in an organic non-aqueous solvent that allows the transport of hydride ions such as AlH.sub.4.sup.- and metal ions during respective discharging and charging steps.

  5. Ultra-sonic observation in niobium hydride precipitation

    International Nuclear Information System (INIS)

    The hidrogen embrittlement of exothermic ocluders, had been considered as due to applied stress induced hydride precipitates leading to brittle fracture. The results of simultaneous measurements of macroscopic deformation and elastic change due to hydride precipitation, using the ultrasonic pulse-echo technique are showed. THen it was tested the possibility of kinectis precipitation parameters evoluation. (Author)

  6. Electrochemical and Optical Properties of Magnesium-Alloy Hydrides Reviewed

    Directory of Open Access Journals (Sweden)

    Thirugnasambandam G. Manivasagam

    2012-10-01

    Full Text Available As potential hydrogen storage media, magnesium based hydrides have been systematically studied in order to improve reversibility, storage capacity, kinetics and thermodynamics. The present article deals with the electrochemical and optical properties of Mg alloy hydrides. Electrochemical hydrogenation, compared to conventional gas phase hydrogen loading, provides precise control with only moderate reaction conditions. Interestingly, the alloy composition determines the crystallographic nature of the metal-hydride: a structural change is induced from rutile to fluorite at 80 at.% of Mg in Mg-TM alloy, with ensuing improved hydrogen mobility and storage capacity. So far, 6 wt.% (equivalent to 1600 mAh/g of reversibly stored hydrogen in MgyTM(1-yHx (TM: Sc, Ti has been reported. Thin film forms of these metal-hydrides reveal interesting electrochromic properties as a function of hydrogen content. Optical switching occurs during (dehydrogenation between the reflective metal and the transparent metal hydride states. The chronological sequence of the optical improvements in optically active metal hydrides starts with the rare earth systems (YHx, followed by Mg rare earth alloy hydrides (MgyGd(1-yHx and concludes with Mg transition metal hydrides (MgyTM(1-yHx. In-situ optical characterization of gradient thin films during (dehydrogenation, denoted as hydrogenography, enables the monitoring of alloy composition gradients simultaneously.

  7. Modular hydride beds for mobile applications

    Energy Technology Data Exchange (ETDEWEB)

    Malinowski, M.E.; Stewart, K.D.

    1997-08-01

    Design, construction, initial testing and simple thermal modeling of modular, metal hydride beds have been completed. Originally designed for supplying hydrogen to a fuel cell on a mobile vehicle, the complete bed design consists of 8 modules and is intended for use on the Palm Desert Vehicle (PDV) under development at the Schatz Energy Center, Humbolt State University. Each module contains approximately 2 kg of a commercially available, low temperature, hydride-forming metal alloy. Waste heat from the fuel cell in the form of heated water is used to desorb hydrogen from the alloy for supplying feed hydrogen to the fuel cell. In order to help determine the performance of such a modular bed system, six modules were constructed and tested. The design and construction of the modules is described in detail. Initial testing of the modules both individually and as a group showed that each module can store {approximately} 30 g of hydrogen (at 165 PSIA fill pressure, 17 C), could be filled with hydrogen in 6 minutes at a nominal, 75 standard liters/min (slm) fueling rate, and could supply hydrogen during desorption at rates of 25 slm, the maximum anticipated hydrogen fuel cell input requirement. Tests made of 5 modules as a group indicated that the behavior of the group run in parallel both in fueling and gas delivery could be directly predicted from the corresponding, single module characteristics by using an appropriate scaling factor. Simple thermal modeling of a module as an array of cylindrical, hydride-filled tubes was performed. The predictions of the model are in good agreement with experimental data.

  8. Preferred hydride growth orientations on oxide-coated gadolinium surfaces

    International Nuclear Information System (INIS)

    Highlights: ► The preferred hydride growth orientations on gadolinium metal coated by a thin oxide layer are presented. ► A preferred growth of the (1 0 0)h plane of the face centered cubic (FCC) GdH2 is observed for the hydride spots forming below the oxidation layer. ► A change to the (1 1 1)h plane of the cubic hydride dominates for the hydride's Growth Centers. ► The texture change is attributed to the surface normal compressive stress component exerted by the oxidation layer on the developing hydride. - Abstract: The initial development of hydrides on polycrystalline gadolinium (Gd), as on some other hydride forming metals, is characterized by two sequential steps. The first step involves the rapid formation of a dense pattern of small hydride spots (referred to as the “small family” of hydrides) below the native oxidation layer. The second stage takes place when some of the “small family” nucleants (referred to as “growth centers”, GCs) break the oxide layer, leading to their rapid growth and finally to the massive hydriding of the sample. In the present study, the texture of the two hydride families was studied, by combining X-ray diffraction (XRD) analysis with a microscopic analysis of the hydride, using scanning electron microscopy (SEM) and atomic force microscopy (AFM). It has been observed that for the “small family”, a preferred growth of the (1 0 0)h plane of the cubic GdH2 takes place, whereas for the GCs, a change to the (1 1 1)h plane of the cubic hydride dominates. These preferred growth orientations were analyzed by their structure relation with the (0 0 .1)m basal plane of the Gd metal. It has been concluded that the above texture change is due to the surface normal compressive stress component exerted by the oxidation overlayer on the developing hydride, preventing the (0 0 .1)m||(1 1 1)h growth orientation. This stress is relieved upon the rupture of that overlayer and the development of the GCs, leading to the

  9. Low-frequency excitations in zirconium hydrides

    International Nuclear Information System (INIS)

    The slow inelastic neutron scattering (INS) on ZrHx systems (x = 0.38, 0.52) revealed new excitations located within the energy range 2-10 MeV. Besides the acoustic vibrations specific to α-HCP Zr and γ-FCO Zr hydride the fine structure of these excitations is clearly observed. The origin of the new observed peaks is not very clear but a proton tunneling or a resonance effect in α-Zr lattice could be taken into account

  10. Tritium immobilization and packaging using metal hydrides

    International Nuclear Information System (INIS)

    Tritium recovered from CANDU heavy water reactors will have to be packaged and stored in a safe manner. Tritium will be recovered in the elemental form, T2. Metal tritides are effective compounds in which to immobilize the tritium as a stable non-reactive solid with a high tritium capacity. The technology necessary to prepare hydrides of suitable metals, such as titanium and zirconium, have been developed and the properties of the prepared materials evaluated. Conceptual designs of packages for containing metal tritides suitable for transportation and long-term storage have been made and initial testing started. (author)

  11. Metal hydrides for concentrating solar thermal power energy storage

    Science.gov (United States)

    Sheppard, D. A.; Paskevicius, M.; Humphries, T. D.; Felderhoff, M.; Capurso, G.; Bellosta von Colbe, J.; Dornheim, M.; Klassen, T.; Ward, P. A.; Teprovich, J. A.; Corgnale, C.; Zidan, R.; Grant, D. M.; Buckley, C. E.

    2016-04-01

    The development of alternative methods for thermal energy storage is important for improving the efficiency and decreasing the cost of concentrating solar thermal power. We focus on the underlying technology that allows metal hydrides to function as thermal energy storage (TES) systems and highlight the current state-of-the-art materials that can operate at temperatures as low as room temperature and as high as 1100 °C. The potential of metal hydrides for thermal storage is explored, while current knowledge gaps about hydride properties, such as hydride thermodynamics, intrinsic kinetics and cyclic stability, are identified. The engineering challenges associated with utilising metal hydrides for high-temperature TES are also addressed.

  12. Recent advances in metal hydrides for clean energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Ronnebro, Ewa; Majzoub, Eric H.

    2013-06-01

    Metal hydrides are a fascinating class of materials that can be utilized for a surprising variety of clean energy applications, including smart solar collectors, smart windows, sensors, thermal energy storage, and batteries, in addition to their traditional application for hydrogen storage. Over the past decade, research on metal hydrides for hydrogen storage increased due to global governmental incentives and an increased focus on hydrogen storage research for polymer electrolyte membrane fuel cell operation. Tremendous progress has been made in so-called complex metal hydrides for hydrogen storage applications with the discovery of many new hydrides containing covalently bound complex anions. Many of these materials have applications beyond hydrogen storage and are being investigated for lithium-ion battery separator and anode materials. In this issue of MRS Bulletin , we present the state of the art of key evolving metal-hydride-based clean energy technologies with an outlook toward future needs.

  13. Helium trapping at erbium oxide precipitates in erbium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Foiles, Stephen M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Battaile, Corbett Chandler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-02-01

    The formation of He bubbles in erbium tritides is a significant process in the aging of these materials. Due to the long-standing uncertainty about the initial nucleation process of these bubbles, there is interest in mechanisms that can lead to the localization of He in erbium hydrides. Previous work has been unable to identify nucleation sites in homogeneous erbium hydride. This work builds on the experimental observation that erbium hydrides have nano- scale erbium oxide precipitates due to the high thermodynamic stability of erbium oxide and the ubiquitous presence of oxygen during materials processing. Fundamental DFT calculations indicate that the He is energetically favored in the oxide relative to the bulk hydride. Activation energies for the motion of He in the oxide and at the oxide-hydride interface indicate that trapping is kinetically feasible. A simple kinetic Monte Carlo model is developed that demonstrates the degree of trapping of He as a function of temperature and oxide fraction.

  14. Results of NDE Technique Evaluation of Clad Hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Dennis C. Kunerth

    2014-09-01

    This report fulfills the M4 milestone, M4FT-14IN0805023, Results of NDE Technique Evaluation of Clad Hydrides, under Work Package Number FT-14IN080502. During service, zirconium alloy fuel cladding will degrade via corrosion/oxidation. Hydrogen, a byproduct of the oxidation process, will be absorbed into the cladding and eventually form hydrides due to low hydrogen solubility limits. The hydride phase is detrimental to the mechanical properties of the cladding and therefore it is important to be able to detect and characterize the presence of this constituent within the cladding. Presently, hydrides are evaluated using destructive examination. If nondestructive evaluation techniques can be used to detect and characterize the hydrides, the potential exists to significantly increase test sample coverage while reducing evaluation time and cost. To demonstrate the viability this approach, an initial evaluation of eddy current and ultrasonic techniques were performed to demonstrate the basic ability to these techniques to detect hydrides or their effects on the microstructure. Conventional continuous wave eddy current techniques were applied to zirconium based cladding test samples thermally processed with hydrogen gas to promote the absorption of hydrogen and subsequent formation of hydrides. The results of the evaluation demonstrate that eddy current inspection approaches have the potential to detect both the physical damage induced by hydrides, e.g. blisters and cracking, as well as the combined effects of absorbed hydrogen and hydride precipitates on the electrical properties of the zirconium alloy. Similarly, measurements of ultrasonic wave velocities indicate changes in the elastic properties resulting from the combined effects of absorbed hydrogen and hydride precipitates as well as changes in geometry in regions of severe degradation. However, for both approaches, the signal responses intended to make the desired measurement incorporate a number of contributing

  15. Nanoindentation measurements of the mechanical properties of zirconium matrix and hydrides in unirradiated pre-hydrided nuclear fuel cladding

    Science.gov (United States)

    Rico, A.; Martin-Rengel, M. A.; Ruiz-Hervias, J.; Rodriguez, J.; Gomez-Sanchez, F. J.

    2014-09-01

    It is well known that the mechanical properties of the nuclear fuel cladding may be affected by the presence of hydrides. The average mechanical properties of hydrided cladding have been extensively investigated from a macroscopic point of view. In addition, the mechanical and fracture properties of bulk hydride samples fabricated from zirconium plates have also been reported. In this paper, Young's modulus, hardness and yield stress are measured for each phase, namely zirconium hydrides and matrix, of pre-hydrided nuclear fuel cladding. To this end, nanoindentation tests were performed on ZIRLO samples in as-received state, on a hydride blister and in samples with 150 and 1200 ppm of hydrogen homogeneously distributed along the hoop direction of the cladding. The results show that the measured mechanical properties of the zirconium hydrides and ZIRLO matrix (Young's modulus, hardness and yield stress) are rather similar. From the experimental data, the hydride volume fraction in the cladding samples with 150 and 1200 ppm was estimated and the average mechanical properties were calculated by means of the rule of mixtures. These values were compared with those obtained from ring compression tests. Good agreement between the results obtained by both methods was found.

  16. Development of hydride absorber for fast reactor. Application of hafnium hydride to control rod of large fast reactor

    International Nuclear Information System (INIS)

    The application of hafnium hydride (Hf-hydride) to a control rod for a large fast reactor where the B4C control rod is originally employed is studied. Three types of Hf-hydride control rods are designed. The control rod worth and its change during the burnup are evaluated for different hydrogen-to-hafnium ratios and are compared with those of the original B4C control rod. The result indicates that the worths of the Hf-hydride and the 10B-enriched B4C control rods are approximately the same, and the lifetime of the Hf-hydride control rod is almost four times longer than that of the 10B-enriched B4C control rod. The core performances of the shutdown margin, sodium void reactivity, Doppler reactivity coefficient, and breeding ratio are analyzed. It is indicated that those for the Hf-hydride control rod are almost the same as those for the original B4C control rod. The behavior of neutrons moderated by the Hf-hydride control rod is analyzed. It is confirmed that the Hf-hydride control rod does not cause any thermal spike problems in the fast reactor core. (author)

  17. Scintillation efficiency of liquid argon in low energy neutron-argon scattering

    International Nuclear Information System (INIS)

    Experiments searching for weak interacting massive particles with noble gases such as liquid argon require very low detection thresholds for nuclear recoils. A determination of the scintillation efficiency is crucial to quantify the response of the detector at low energy. We report the results obtained with a small liquid argon cell using a monoenergetic neutron beam produced by a deuterium-deuterium fusion source. The light yield relative to electrons was measured for six argon recoil energies between 11 and 120 keV at zero electric drift field

  18. Scintillation efficiency of liquid argon in low energy neutron-argon scattering

    CERN Document Server

    Creus, W; Amsler, C; Ferella, A D; Rochet, J; Scotto-Lavina, L; Walter, M

    2015-01-01

    Experiments searching for weak interacting massive particles with noble gases such as liquid argon require very low detection thresholds for nuclear recoils. A determination of the scintillation efficiency is crucial to quantify the response of the detector at low energy. We report the results obtained with a small liquid argon cell using a monoenergetic neutron beam produced by a deuterium-deuterium fusion source. The light yield relative to electrons was measured for six argon recoil energies between 11 and 120 keV at zero electric drift field.

  19. NATO Advanced Study Institute on Metal Hydrides

    CERN Document Server

    1981-01-01

    In the last five years, the study of metal hydrides has ex­ panded enormously due to the potential technological importance of this class of materials in hydrogen based energy conversion schemes. The scope of this activity has been worldwide among the industrially advanced nations. There has been a consensus among researchers in both fundamental and applied areas that a more basic understanding of the properties of metal/hydrogen syster;,s is required in order to provide a rational basis for the selection of materials for specific applications. The current worldwide need for and interest in research in metal hydrides indicated the timeliness of an Advanced Study Insti­ tute to provide an in-depth view of the field for those active in its various aspects. The inclusion of speakers from non-NATO coun­ tries provided the opportunity for cross-fertilization of ideas for future research. While the emphasis of the Institute was on basic properties, there was a conscious effort to stimulate interest in the applic...

  20. Contraction ionization waves in the argon contracted discharge

    International Nuclear Information System (INIS)

    An investigation of ionization waves in the argon contracted discharge and a definition of their arising propagation mechanism accounting for the specificity of elementary pocesses characteristic of argon are presented. (author)

  1. Thermal decomposition of barium valerate in argon

    DEFF Research Database (Denmark)

    Torres, P.; Norby, Poul; Grivel, Jean-Claude

    2015-01-01

    The thermal decomposition of barium valerate (Ba(C4H9CO2)(2)/Ba-pentanoate) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction and hot-stage optical microscopy. Melting takes place in two different steps, at 200 degrees C and 280...

  2. Antiapoptotic activity of argon and xenon.

    Science.gov (United States)

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

    2013-08-15

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

  3. Keeping argon under a graphene lid-Argon intercalation between graphene and nickel(111)

    Science.gov (United States)

    Späth, Florian; Gotterbarm, Karin; Amende, Max; Bauer, Udo; Gleichweit, Christoph; Höfert, Oliver; Steinrück, Hans-Peter; Papp, Christian

    2016-01-01

    We report on the intercalation of graphene grown on a Ni(111) crystal with argon. Argon is implanted in the Ni(111) crystal by ion bombardment before graphene growth, and diffuses to the surface during the growth of graphene at elevated temperatures. Graphene acts as an atomically thin barrier and keeps the argon underneath. We investigated this system with high resolution X-ray photoelectron spectroscopy. From our experiments we determined the mean quantities of argon under graphene. From our analysis, a simple model to determine the pressure under the graphene layer is presented. In our measurements, we find an increased thermal stability of the intercalated graphene as compared to non-intercalated graphene on Ni(111).

  4. Isotope exchange between gaseous hydrogen and uranium hydride powder

    International Nuclear Information System (INIS)

    Highlights: • Isotope exchange between hydrogen gas and uranium hydride powder can be rapid and reversible. • Gas–solid exchange rate is controlled by transport within ∼0.7 μm hydride particles. • Gas chromatographic separation of hydrogen isotopes using uranium hydride is feasible. - Abstract: Isotope exchange between gaseous hydrogen and solid uranium hydride has been studied by flowing hydrogen (deuterium) gas through packed powder beds of uranium deuteride (hydride). We used a residual gas analyzer system to perform real-time analysis of the effluent gas composition. We also developed an exchange and transport model and, by fitting it to the experimental data, extracted kinetic parameters for the isotope exchange reaction. Our results suggest that, from approximately 70 to 700 kPa and 25 to 400 °C, the gas-to-solid exchange rate is controlled by hydrogen and deuterium transport within the ∼0.7 μm diameter uranium hydride particles. We use our kinetic parameters to show that gas chromatographic separation of hydrogen and deuterium using uranium hydride could be feasible

  5. Argon Laser Treatment of Strawberry Hemangioma in Infancy

    OpenAIRE

    Achauer, Bruce M.; Vander Kam, Victoria M.

    1985-01-01

    Argon laser therapy is effective for removing port-wine stains and for reducing cutaneous vascular and pigmented lesions. Strawberry hemangiomas, being much thicker lesions than port-wine stains, were considered not appropriate for argon laser treatment. Using argon laser therapy in 13 cases of strawberry hemangioma, we achieved poor to dramatic results.

  6. Argon laser treatment of strawberry hemangioma in infancy.

    Science.gov (United States)

    Achauer, B M; Vander Kam, V M

    1985-11-01

    Argon laser therapy is effective for removing port-wine stains and for reducing cutaneous vascular and pigmented lesions. Strawberry hemangiomas, being much thicker lesions than port-wine stains, were considered not appropriate for argon laser treatment. Using argon laser therapy in 13 cases of strawberry hemangioma, we achieved poor to dramatic results. PMID:4082569

  7. Hydrogen storage in metal hydrides and complex hydrides; Wasserstoffspeicherung in Metall- und komplexen Hydriden - Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Bielmann, M.; Zuettel, A.

    2007-07-01

    This final report for the Swiss Federal Office of Energy (SFOE), reports on work done in 2007 at the Swiss Federal Laboratories for Materials Science and Technology EMPA on the storage of hydrogen in metal hydrides and complex hydrides. In particular, the use of tetrahydroborates is noted. The potential of this class of materials is stressed. The structures at room-temperature were examined using neutron and X-ray diffraction methods. Thermodynamic methods helped determine the thermodynamic stability of the materials. Also, a complete energy diagram for the materials was developed. The use of silicon oxide to reduce activation energy and its catalytic effects are discussed. The challenges placed by desorption mechanisms are noted. The authors note that reversibility is basically proven.

  8. PIE techniques for hydride reorientation test at NDC

    International Nuclear Information System (INIS)

    Dry storage of spent fuels in the interim storage facility is being planned in Japan. However, the gradual deterioration of the mechanical property of fuel cladding due to internal pressure and temperature during the storage term is known. Therefore, the integrity of stored fuel rods should be confirmed before the start of dry storage. For the last several years, NDC had a lot of experiences on the hydride reorientation test. The specimen preparation techniques on the hydride reorientation test and the mechanical testing techniques after the hydride reorientation are shown in this paper. (author)

  9. Hydrogen storage in sodium aluminum hydride.

    Energy Technology Data Exchange (ETDEWEB)

    Ozolins, Vidvuds; Herberg, J.L. (Lawrence Livermore National Laboratories, Livermore, CA); McCarty, Kevin F.; Maxwell, Robert S. (Lawrence Livermore National Laboratories, Livermore, CA); Stumpf, Roland Rudolph; Majzoub, Eric H.

    2005-11-01

    Sodium aluminum hydride, NaAlH{sub 4}, has been studied for use as a hydrogen storage material. The effect of Ti, as a few mol. % dopant in the system to increase kinetics of hydrogen sorption, is studied with respect to changes in lattice structure of the crystal. No Ti substitution is found in the crystal lattice. Electronic structure calculations indicate that the NaAlH{sub 4} and Na{sub 3}AlH{sub 6} structures are complex-ionic hydrides with Na{sup +} cations and AlH{sub 4}{sup -} and AlH{sub 6}{sup 3-} anions, respectively. Compound formation studies indicate the primary Ti-compound formed when doping the material at 33 at. % is TiAl{sub 3} , and likely Ti-Al compounds at lower doping rates. A general study of sorption kinetics of NaAlH{sub 4}, when doped with a variety of Ti-halide compounds, indicates a uniform response with the kinetics similar for all dopants. NMR multiple quantum studies of solution-doped samples indicate solvent interaction with the doped alanate. Raman spectroscopy was used to study the lattice dynamics of NaAlH{sub 4}, and illustrated the molecular ionic nature of the lattice as a separation of vibrational modes between the AlH{sub 4}{sup -} anion-modes and lattice-modes. In-situ Raman measurements indicate a stable AlH{sub 4}{sup -} anion that is stable at the melting temperature of NaAlH{sub 4}, indicating that Ti-dopants must affect the Al-H bond strength.

  10. The progress of nanocrystalline hydride electrode materials

    International Nuclear Information System (INIS)

    This paper reviews research at the Institute of Materials Science and Engineering, Poznan University of Technology, on the synthesis of nanocrystalline hydride electrode materials. Nanocrystalline materials have been synthesized by mechanical alloying (MA) followed by annealing. Examples of the materials include TiFe-, ZrV2-, LaNi5 and Mg2Ni-type phases. Details on the process used and the enhancement of properties due to the nanoscale structures are presented. The synthesized alloys were used as negative electrode materials for Ni-MH battery. The properties of hydrogen host materials can be modified substantially by alloying to obtain the desired storage characteristics. For example, it was found that the respective replacement of Fe in TiFe by Ni and/or by Cr, Co, Mo improved not only the discharge capacity but also the cycle life of these electrodes. The hydrogen storage properties of nanocrystalline ZrV2- and LaNi5-type powders prepared by mechanical alloying and annealing show no big difference with those of melt casting (polycrystalline) alloys. On the other hand, a partial substitution of Mg by Mn or Al in Mg2Ni alloy leads to an increase in discharge capacity, at room temperature. Furthermore, the effect of the nickel and graphite coating on the structure of some nanocrystalline alloys and the electrodes characteristics were investigated. In the case of Mg2Ni-type alloy mechanical coating with graphite effectively reduced the degradation rate of the studied electrode materials. The combination of a nanocrystalline TiFe-, ZrV2- and LaNi5-type hydride electrodes and a nickel positive electrode to form a Ni-MH battery, has been successful. (authors)

  11. Artificial exomuscle investigations for applications-metal hydride

    International Nuclear Information System (INIS)

    In pursuing the development of bionic devices, Victhom identified a need for technologies that could replace current motorized systems and be better integrated into the human body motion. The actuators used to obtain large displacements are noisy, heavy, and do not adequately reproduce human muscle behavior. Subsequently, a project at Victhom was devoted to the development of active materials to obtain an artificial exomuscle actuator. An exhaustive literature review was done at Victhom to identify promising active materials for the development of artificial muscles. According to this review, metal hydrides were identified as a promising technology for artificial muscle development. Victhom's investigations focused on determining metal hydride actuator potential in the context of bionics technology. Based on metal hydride properties and artificial muscle requirements such as force, displacement and rise time, an exomuscle was built. In addition, a finite element model, including heat and mass transfer in the metal hydride, was developed and implemented in FEMLAB software. (review article)

  12. Out-of-pile accelerated hydriding of Zircaloy fasteners

    International Nuclear Information System (INIS)

    Mechanical joints between Zircaloy and nickel-bearing alloys, mainly the Zircaloy-4/Inconel-600 combination, were exposed to water at 4500F and 5200F to study hydriding of Zircaloy in contact with a dissimilar metal. Accelerated hydriding of the Zircaloy occurred at both temperatures. At 4500F the dissolved hydrogen level of the water was over ten times that at 5200F. At 5200F the initially high hydrogen ingress rate decreased rapidly as exposure time increased and was effectively shut off in about 25 days. Severely hydrided Zircaloy components successfully withstood thermal cycling and mechanical testing. Chromium plating of the nickel-bearing parts was found to be an effective and practical barrier in preventing nickel-alloy smearing and accelerated hydriding of Zircaloy

  13. Artificial exomuscle investigations for applications-metal hydride

    Energy Technology Data Exchange (ETDEWEB)

    Crevier, Marie-Charlotte; Richard, Martin; Rittenhouse, D Matheson; Roy, Pierre-Olivier; Bedard, Stephane [Victhom Human Bionics Inc., Saint-Augustin-de-Desmaures, QC (Canada)

    2007-03-01

    In pursuing the development of bionic devices, Victhom identified a need for technologies that could replace current motorized systems and be better integrated into the human body motion. The actuators used to obtain large displacements are noisy, heavy, and do not adequately reproduce human muscle behavior. Subsequently, a project at Victhom was devoted to the development of active materials to obtain an artificial exomuscle actuator. An exhaustive literature review was done at Victhom to identify promising active materials for the development of artificial muscles. According to this review, metal hydrides were identified as a promising technology for artificial muscle development. Victhom's investigations focused on determining metal hydride actuator potential in the context of bionics technology. Based on metal hydride properties and artificial muscle requirements such as force, displacement and rise time, an exomuscle was built. In addition, a finite element model, including heat and mass transfer in the metal hydride, was developed and implemented in FEMLAB software. (review article)

  14. Flow Parameters of Argon plasma Discharge

    International Nuclear Information System (INIS)

    Owing to the viscosity, the plasma will be adhering to the inner surface of the outer electrode and outer surface of the inner one. As result that the discharge will be eroding the walls of coaxial system. The thickness of the boundary layer near the walls has been estimated at different positions from the breech of coaxial plasma gun. It is found that the thickness of layer 0.008 cm at the end of inner electrode (17 cm). A coaxial plasma gun device is operated in argon gas at ambient pressure 0.6 Torr and discharge voltage about 10 KV. The electron temperature of argon discharge has been determined by using spectroscopic technique. It is found that kTe=3.4 eV. By knowing the thickness of the boundary layer, the density can be determined. The Reynolds number R=105 and Mach number M=5 i.e. the flow is compressible and hypersonic

  15. Argon laser irradiation of the otolithic organ

    Energy Technology Data Exchange (ETDEWEB)

    Okuno, T.; Nomura, Y.; Young, Y.H.; Hara, M. (Univ. of Tokyo (Japan))

    1990-12-01

    An argon laser was used to irradiate the otolithic organs of guinea pigs and cynomolgus monkeys. After stapedectomy, the argon laser (1.5 W x 0.5 sec/shot) irradiated the utricle or saccule without touching the sensory organs. The stapes was replaced over the oval window after irradiation. The animals used for acute observation were killed immediately for morphologic studies; those used for long-term observation were kept alive for 2, 4, or 10 weeks. Acute observation revealed that sensory and supporting cells were elevated from the basement membrane only in the irradiated area. No rupture of the membranous labyrinth was observed. Long-term observation revealed that the otolith of the macula utriculi had disappeared in 2-week specimens. The entire macula utricili had disappeared in 10-week specimens. No morphologic changes were observed in cochlea, semicircular canals, or membranous labyrinth. The saccule showed similar changes.

  16. Abnormal epidermal changes after argon laser treatment

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, R.A.; Knobler, R.M.; Aberer, E.; Klein, W.; Kocsis, F.; Ott, E. (Univ. of Vienna (Austria))

    1991-02-01

    A 26-year-old woman with a congenital port-wine stain on the forehead was treated three times at 2-month intervals with an argon laser. Six months after the last treatment, moderate blanching and mild scaling confined to the treated area was observed. A biopsy specimen of the treated area revealed a significant decrease in ectatic vessels. However, epidermal changes similar to those of actinic keratosis with disorganized cell layers and marked cytologic abnormalities were seen. Analysis of peripheral blood lymphocytes for a defect in DNA repair was negative. Multiple, argon laser-induced photothermal effects may be responsible for the changes observed in our case and may lead to premalignant epidermal transformation.

  17. Explanation of the memory effect in argon

    Directory of Open Access Journals (Sweden)

    Marković Vidosav

    2005-01-01

    Full Text Available Memory effect - the long time variation of the electrical breakdown time delay on the relaxation time td (τ was observed in argon 24 hours after relaxation times and explained by the long-lived metastable states remaining from the preceding glow. However, the quenching processes reducing the effective lifetime of metastable states several orders of magnitude below that relevant for the time scale of observation were neglected. By applying approximate gas phase models it was found that the early afterglow kinetics up to hundreds of milliseconds is dominated by the decay of molecular argon ions Ar2+ and the approximate value of their ambipolar diffusion coefficient is determined. After that, nitrogen atoms present as impurities and recombined on the cathode surface and/or field emission determine the breakdown time delay down to the cosmic rays and natural radioactivity level.

  18. Electronic structure and optical properties of lightweight metal hydrides

    NARCIS (Netherlands)

    Setten, van M.J.; Popa, V.A.; Wijs, de G.A.; Brocks, G.

    2007-01-01

    We study the dielectric functions of the series of simple hydrides LiH, NaH, MgH2, and AlH3, and of the complex hydrides Li3AlH6, Na3AlH6, LiAlH4, NaAlH4, and Mg(AlH4)2, using first-principles density-functional theory and GW calculations. All compounds are large gap insulators with GW single-partic

  19. Electronic structure of ternary hydrides based on light elements

    Energy Technology Data Exchange (ETDEWEB)

    Orgaz, E. [Departamento de Fisica y Quimica Teorica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, CP 04510 Coyoacan, Mexico, D.F. (Mexico)]. E-mail: orgaz@eros.pquim.unam.mx; Membrillo, A. [Departamento de Fisica y Quimica Teorica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, CP 04510 Coyoacan, Mexico, D.F. (Mexico); Castaneda, R. [Departamento de Fisica y Quimica Teorica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, CP 04510 Coyoacan, Mexico, D.F. (Mexico); Aburto, A. [Departamento de Fisica, Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, CP 04510 Coyoacan, Mexico, D.F. (Mexico)

    2005-12-08

    Ternary hydrides based on light elements are interesting owing to the high available energy density. In this work we focused into the electronic structure of a series of known systems having the general formula AMH{sub 4}(A=Li,Na,M=B,Al). We computed the energy bands and the total and partial density of states using the linear-augmented plane waves method. In this report, we discuss the chemical bonding in this series of complex hydrides.

  20. Thin-film metal hydrides for solar energy applications

    OpenAIRE

    2012-01-01

    Thin-film metal hydrides may become important solar energy materials in the future. This thesis demonstrates interesting material properties of metal hydride films, relevant for applications as semiconducting materials for photovoltaic (PV) solar cells and for regulation of light using smart window technology. List of papers. Papers II-VI are removed from the thesis due to copyright restrictions. Paper I C. Platzer-Björkman, T. Mongstad, S. Zh. Karazhanov, J. P. Mæhlen, E. S. Marst...

  1. Method of selective reduction of polyhalosilanes with alkyltin hydrides

    Science.gov (United States)

    Sharp, Kenneth G.; D'Errico, John J.

    1989-01-01

    The invention relates to the selective and stepwise reduction of polyhalosilanes by reacting at room temperature or below with alkyltin hydrides without the use of free radical intermediates. Alkyltin hydrides selectively and stepwise reduce the Si--Br, Si--Cl, or Si--I bonds while leaving intact any Si--F bonds. When two or more different halogens are present on the polyhalosilane, the halogen with the highest atomic weight is preferentially reduced.

  2. Method of selective reduction of halodisilanes with alkyltin hydrides

    Science.gov (United States)

    D'Errico, John J.; Sharp, Kenneth G.

    1989-01-01

    The invention relates to the selective and sequential reduction of halodisilanes by reacting these compounds at room temperature or below with trialkyltin hydrides or dialkyltin dihydrides without the use of free radical intermediates. The alkyltin hydrides selectively and sequentially reduce the Si-Cl, Si-Br or Si-I bonds while leaving intact the Si-Si and Si-F bonds present.

  3. Anatomy of an Inversion - Argon Isotopes

    Science.gov (United States)

    Zamick, L.; Sharon, Y. Y.; Robinson, S. J. Q.

    2012-02-01

    Two different interactions give similar results for excitation energies and g factors of 2+1 states for most even-even argon isotopes except 46Ar. This is explained in terms of an inversion in J = ½+ and levels in 47K which is successfully obtained by one of the interactions but not the other. This example shows the possible dangers of nuclear astrophysics extrapolations.

  4. Novel fuel cell stack with coupled metal hydride containers

    Science.gov (United States)

    Liu, Zhixiang; Li, Yan; Bu, Qingyuan; Guzy, Christopher J.; Li, Qi; Chen, Weirong; Wang, Cheng

    2016-10-01

    Air-cooled, self-humidifying hydrogen fuel cells are often used for backup and portable power sources, with a metal hydride used as the hydrogen storage material. To provide a stable hydrogen flow to the fuel cell stack, heat must be provided to the metal hydride. Conventionally, the heat released from the exothermic reaction of hydrogen and oxygen in the fuel cell stack to the exhaust air is used to heat a separate metal hydride container. In this case, the heat is only partially used instead of being more closely coupled because of the heat transfer resistances in the system. To achieve better heat integration, a novel scheme is proposed whereby hydrogen storage and single fuel cells are more closely coupled. Based on this idea, metal hydride containers in the form of cooling plates were assembled between each pair of cells in the stack so that the heat could be directly transferred to a metal hydride container of much larger surface-to-volume ratio than conventional separate containers. A heat coupled fuel cell portable power source with 10 cells and 11 metal hydride containers was constructed and the experimental results show that this scheme is beneficial for the heat management of fuel cell stack.

  5. Optimization of Hydride Rim Formation in Unirradiated Zr 4 Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Shimskey, Rick W.; Hanson, Brady D.; MacFarlan, Paul J.

    2013-09-30

    The purpose of this work is to build on the results reported in the M2 milestone M2FT 13PN0805051, document number FCRD-USED-2013-000151 (Hanson, 2013). In that work, it was demonstrated that unirradiated samples of zircaloy-4 cladding could be pre-hydrided at temperatures below 400°C in pure hydrogen gas and that the growth of hydrides on the surface could be controlled by changing the surface condition of the samples and form a desired hydride rim on the outside diameter of the cladding. The work performed at Pacific Northwest National Laboratory since the issuing of the M2 milestone has focused its efforts to optimize the formation of a hydride rim on available zircaloy-4 cladding samples by controlling temperature variation and gas flow control during pre-hydriding treatments. Surface conditioning of the outside surface was also examined as a variable. The results of test indicate that much of the variability in the hydride thickness is due to temperature variation occurring in the furnaces as well as how hydrogen gas flows across the sample surface. Efforts to examine other alloys, gas concentrations, and different surface conditioning plan to be pursed in the next FY as more cladding samples become available

  6. Effect of niobium additions on initial hydriding kinetics of uranium

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ruiwen, E-mail: ruiwenli@163.com; Wang, Xiaolin

    2014-06-01

    To study the behavior of hydrogen corrosion at the surface of U, U–2.5 wt%Nb alloy and U–5.7 wt%Nb, a gas–solid reaction system with an in situ microscope was designed. The nucleation and growth of the hydride of the alloy were continuously observed and recorded by a computer. The different characteristics of the hydrides on U metal and U–2.5 wt%Nb showed that the later alloy is more susceptible to hydrogen corrosion than the former. The growth rate of hydride of U–2.5 wt%Nb, calculated by measuring the perimeter of the hydride spots recorded by the in situ microscope, exhibited a reaction temperature dependency in the range of 40–160 °C, for pressure of 0.8 × 10{sup 5} Pa. An Arrhenius plot for growth rate versus temperature yielded activation energy of 24.34 kJ/mol for the hydriding of U–2.5 wt%Nb alloy. The maximum hydriding rate was obtained at 125 °C, whose thermodynamics reason was discussed.

  7. Determination of Selenium in Marine Aquatic Products by Hydride Generation-atomic Fluorescence Spectrometry (HG-AFS)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhaohui; GAO Xin; Tashiro Yuri; Hiroo Ogawa

    2005-01-01

    A method for the analysis of selenium in marine aquatic products by HG-AFS has been investigated. The method is based on the reduction of inorganic selenium to volatile SeH2 which is bubbled out by carrier gas of pure argon, and then swept to Ar-H2 flame quarts atomizer to measure its fluorescence intensity. The hydride generation, transportation, atomization and some instrumental parameters were studied by a kind of orthogonal design. The optimum conditions selected are as follows: reactive acidity, 20% HC1; the amount of NaBH4, 4.9mL; gas flow of argon, 600mLmin-1; atomizing temperature, 200 ℃; negative high voltage, -300V; light current, 100 mA; integral time, 7s. The detection limit of the presented method is 0.072μgL-1 for selenium. The calibration curve shows a satisfactory line inthe concentration range from 0.000 to1.000μgL-1 Se. The recovery is 95.8%-102.2%.

  8. Chemical Hydride Slurry for Hydrogen Production and Storage

    Energy Technology Data Exchange (ETDEWEB)

    McClaine, Andrew W

    2008-09-30

    The purpose of this project was to investigate and evaluate the attractiveness of using a magnesium chemical hydride slurry as a hydrogen storage, delivery, and production medium for automobiles. To fully evaluate the potential for magnesium hydride slurry to act as a carrier of hydrogen, potential slurry compositions, potential hydrogen release techniques, and the processes (and their costs) that will be used to recycle the byproducts back to a high hydrogen content slurry were evaluated. A 75% MgH2 slurry was demonstrated, which was just short of the 76% goal. This slurry is pumpable and storable for months at a time at room temperature and pressure conditions and it has the consistency of paint. Two techniques were demonstrated for reacting the slurry with water to release hydrogen. The first technique was a continuous mixing process that was tested for several hours at a time and demonstrated operation without external heat addition. Further work will be required to reduce this design to a reliable, robust system. The second technique was a semi-continuous process. It was demonstrated on a 2 kWh scale. This system operated continuously and reliably for hours at a time, including starts and stops. This process could be readily reduced to practice for commercial applications. The processes and costs associated with recycling the byproducts of the water/slurry reaction were also evaluated. This included recovering and recycling the oils of the slurry, reforming the magnesium hydroxide and magnesium oxide byproduct to magnesium metal, hydriding the magnesium metal with hydrogen to form magnesium hydride, and preparing the slurry. We found that the SOM process, under development by Boston University, offers the lowest cost alternative for producing and recycling the slurry. Using the H2A framework, a total cost of production, delivery, and distribution of $4.50/kg of hydrogen delivered or $4.50/gge was determined. Experiments performed at Boston

  9. Simultaneous Heat and Mass Transfer in DU Hydriding

    International Nuclear Information System (INIS)

    The sources of nuclear fusion reaction are deuterium (D) and tritium (T). Generally, D is fused into T, which generates helium atoms and neutrons. At this time, a tremendous amount of energy is generated. D + T → 4He + n (E = 17.6 MeV) Hydrogen is a gas, and cannot be stored in large amounts. In addition, it can be explosive. Therefore, one of the storing methods for hydrogen is metal hydride. In this research, several kinds of metal hydrides including U, Zr, ZrCo, ZrNi, and LaNi5 have been simulated through modeling work of hydrogen absorption, desorption, and pressure effect in a bed using DU. For the exact modeling of the hydriding process, it is necessary to calculate simultaneous heat and mass transfer because, in the hydriding process, not only is hydrogen gas transported by mass transport and chemisorption but heat transfer also occurs through absorption. Therefore, in this paper, we tried to calculate the simultaneous heat and mass transfer using numerical analysis methods. Simultaneous heat and mass transfer in DU hydriding is well fitted compared to the experimental data, and is more reasonable considering only one variable. The hydriding process changes the temperature and atomic ratio simultaneously, and thus it is necessary to consider in company with two transport phenomena. The numerical analysis method applied Euler's method; however, the Runge-Kutta method is a more widely used numerical solution of a differential equation. Therefore, when analyzing the hydriding process, Runge-Kutta or another method will henceforth be applied

  10. Development of a low-cost inductively coupled argon plasma

    International Nuclear Information System (INIS)

    The aim of this investigation is to drastically reduce running costs of an inductively coupled plasma. This is done by reducing the argon consumption from 20 l/min to about 1 l/min. First, a sample introduction system operating on 0.1 l/min of carrier argon is described. This system ensures a high ratio of plasma argon and carrier argon even at the low total argon consumptions intended. Next, the developed low consumption plasma is presented. In the proposed design, air is blown perpendicularly against the outside of the torch. A different coil has been developed to make air-cooling efficient. Preliminary data on coupling efficiency for the air-cooled plasma are presented. A similarly low argon consumption has been achieved with water as an external coolant medium. It is concluded that a cheaper alternative to the current ICP has become available. (Auth.)

  11. Reactions of NO with nitrogen hydrides x

    Science.gov (United States)

    Mebel, A. M.; Lin, M. C.

    In this review, we consider the reactions of NO ( x 1,2) with the nitrogen x hydrides NH, NH and NH . The reactions are relevant to the post-combustion, non-catalytic reduction of NO with NH in the thermal de-NO process and with x x HNCO in the rapid reduction of NO as well as to the thermal decomposition of x some high-energy materials, including ammonium dinitramide. The practical importance has motivated considerable theoretical interest in these reactions. We review numerous ab - initio molecular orbital studies of potential energy surfaces for NO NH and theoretical calculations of their kinetic parameters, such as x y thermal rate constants and branching ratios of various products. The most advanced theoretical calculations are carried out using the Gaussian-2 family of methods which provides the chemical accuracy (within 2 kcal mol ) for the energetics and molecular parameters of the reactants, products, intermediates and transition states. We present a detailed comparison of the theoretical results with available experimental data. We show that the reactions of NO with NH and NH x are very fast because they occur without a barrier and lead to the formation of multiple products which include radicals and stable molecules. The reactions of NO with NH , taking place by the H abstraction to form NH and HNO , are slow x x but still relevant to the NH de-NO system, because of their fast reverse processes x which have not yet been measured experimentally.

  12. Effects of Nitrogen contamination in liquid Argon

    Science.gov (United States)

    Acciarri, R.; Antonello, M.; Baibussinov, B.; Baldo-Ceolin, M.; Benetti, P.; Calaprice, F.; Calligarich, E.; Cambiaghi, M.; Canci, N.; Carbonara, F.; Cavanna, F.; Centro, S.; Cocco, A. G.; Di Pompeo, F.; Fiorillo, G.; Galbiati, C.; Gallo, V.; Grandi, L.; Meng, G.; Modena, I.; Montanari, C.; Palamara, O.; Pandola, L.; Piano Mortari, G. B.; Pietropaolo, F.; Raselli, G. L.; Roncadelli, M.; Rossella, M.; Rubbia, C.; Segreto, E.; Szelc, A. M.; Ventura, S.; Vignoli, C.

    2010-06-01

    A dedicated test of the effects of Nitrogen contamination in liquid Argon has been performed at the INFN-Gran Sasso Laboratory (LNGS, Italy) within the WArP R&D program. A detector has been designed and assembled for this specific task and connected to a system for the injection of controlled amounts of gaseous Nitrogen into the liquid Argon. The purpose of the test is to detect the reduction of the Ar scintillation light emission as a function of the amount of the Nitrogen contaminant injected in the Argon volume. A wide concentration range, spanning from ~ 10-1 ppm up to ~ 103 ppm, has been explored. Measurements have been done with electrons in the energy range of minimum ionizing particles (γ-conversion from radioactive sources). Source spectra at different Nitrogen contaminations are analyzed, showing sensitive reduction of the scintillation yield at increasing concentrations. Direct PMT signal acquisition exploiting high time resolution by fast waveform recording allowed high precision extraction of the main characteristics of the scintillation light emission in contaminated LAr. In particular, the decreasing behavior in lifetime and relative amplitude of the slow component is found to be appreciable starting from Script O(1 ppm) of Nitrogen concentrations. The rate constant of the quenching process induced by Nitrogen in liquid Ar has been found to be kQ(N2) = 0.11 ± 0.01 μs-1ppm-1, consistent with a previous measurement of this quantity but with significant improvement in precision. On the other hand, no evidence for absorption by N2 impurities has been found up to the higher concentrations here explored.

  13. Argon diffusion from biotite at high temperature and pressure

    Institute of Scientific and Technical Information of China (English)

    陈道公; 贾命命; 李彬贤; 陆全明; 谢鸿森; 侯渭

    1995-01-01

    t The experiments of argon diffusion dynamics for biotite were carried out at 700 -1000℃ and 0.5 - 2,0 GPa and the diffusion coefficient and activation energy using different models have been calculated. The results indicate that the pressure does affect the argon diffusion and its effect is opposite to that of temperature. When p increases, the activation energy increases and diffusion coefficient decreases. The relation between pressure, closure temperature and cooling rate has been obtained. It is postulated that in low T and high p conditions, the argon diffusion from the environment to the system could occur and incur the appearance of the external argon in minerals.

  14. Near-infrared scintillation of liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, T. [Fermilab; Escobar, C. O. [Campinas State U.; Lippincott, W. H. [Fermilab; Rubinov, P. [Fermilab

    2016-03-03

    Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 $\\mu$m < $\\lambda$; < 1.5$\\mu$m). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

  15. Near-infrared scintillation of liquid argon

    CERN Document Server

    Alexander, T; Lippincott, W H; Rubinov, P

    2016-01-01

    Since the 1970s it has been known that noble gases scintillate in the near infrared (NIR) region of the spectrum (0.7 $\\mu$m < $\\lambda$; < 1.5$\\mu$m). More controversial has been the question of the NIR light yield for condensed noble gases. We first present the motivation for using the NIR scintillation in liquid argon detectors, then briefly review early as well as more recent efforts and finally show encouraging preliminary results of a test performed at Fermilab.

  16. Argon isotope fractionation induced by stepwise heating

    Science.gov (United States)

    Trieloff, Mario; Falter, Martina; Buikin, Alexei I.; Korochantseva, Ekaterina V.; Jessberger, Elmar K.; Altherr, Rainer

    2005-03-01

    Noble gas isotopes are widely used to elucidate the history of the rocks in which they have been trapped, either from distinct reservoirs or by accumulation following radioactive decay. To extract noble gases from their host rocks, stepwise heating is the most commonly used technique to deconvolve isotopically different components, e.g., atmospheric, in situ radiogenic, or excess radiogenic from mantle or crustal reservoirs. The accurate determination of the isotopic composition of these different components is of crucial importance, e.g., for ages obtained by 40Ar- 39Ar stepheating plateaus. However, diffusion theory-based model calculations predict that the stepwise thermal extraction process from mineral phases induces isotope fractionation and, hence, adulterates the original composition. Such effects are largely unconsidered, as they are small and a compelling experimental observation is lacking. We report the first unequivocal evidence for significant mass fractionation of argon isotopes during thermal extraction, observed on shungite, a carbon-rich Precambrian sedimentary rock. The degree of fractionation, as monitored by 38Ar/ 36Ar and 40Ar/ 36Ar ratios, very well agrees with theoretical predictions assuming an inverse square root dependence of diffusion coefficient and atomic mass, resulting in easier extraction of lighter isotopes. Hence, subatmospheric 40Ar/ 36Ar ratios obtained for argon extracted at low temperatures may not represent paleoatmospheric argon. Shungite argon resembles modern atmospheric composition, but constraints on the timing of trapping appear difficult to obtain, as shungites are multicomponent systems. In 40Ar- 39Ar stepwise heating, the isotope fractionation effect could cause systematic underestimations of plateau ages, between 0.15 and 0.4% depending on age, or considerably higher if samples contain appreciable atmospheric Ar. The magnitude of this effect is similar to the presently achieved uncertainties of this increasingly

  17. Argon Purification Studies and a Novel Liquid Argon Re-circulation System

    CERN Document Server

    Mavrokoridis, K; Coleman, J; Lightfoot, P K; McCauley, N; McCormick, K J; Touramanis, C

    2011-01-01

    Future giant liquid argon (LAr) time projection chambers (TPCs) require a purity of better than 0.1 parts per billion (ppb) to allow the ionised electrons to drift without significant capture by any electronegative impurities. We present a comprehensive study of the effects of electronegative impurity on gaseous and liquid argon scintillation light, an analysis of the efficacy of various purification chemicals, as well as the Liverpool LAr setup, which utilises a novel re-circulation purification system. Of the impurities tested - Air, O_2, H_2O, N_2 and CO_2 in the range of between 0.01 ppm to 1000 ppm - H_2O was found to have the most profound effect on gaseous argon scintillation light, and N_2 was found to have the least. Additionally, a correlation between the slow component decay time and the total energy deposited with 0.01 ppm - 100 ppm O_2 contamination levels in liquid argon has been established. The superiority of molecular sieves over anhydrous complexes at absorbing Ar gas, N_2 gas and H_2O vapou...

  18. Micro-scale fracture experiments on zirconium hydrides and phase boundaries

    Science.gov (United States)

    Chan, H.; Roberts, S. G.; Gong, J.

    2016-07-01

    Fracture properties of micro-scale zirconium hydrides and phase boundaries were studied using microcantilever testing methods. FIB-machined microcantilevers were milled on cross-sectional surfaces of hydrided samples, with the most highly-stressed regions within the δ-hydride film, within the α-Zr or along the Zr-hydride interface. Cantilevers were notched using the FIB and then tested in bending using a nanoindenter. Load-displacement results show that three types of cantilevers have distinct deformation properties. Zr cantilevers deformed plastically. Hydride cantilevers fractured after a small amount of plastic flow; the fracture toughness of the δ-hydride was found to be 3.3 ± 0.4 MPam1/2 and SEM examination showed transgranular cleavage on the fracture surfaces. Cantilevers notched at the Zr-hydride interface developed interfacial voids during loading, at loads considerably lower than that which initiate brittle fracture of hydrides.

  19. Numerical simulation and performance test of metal hydride hydrogen storage system

    Directory of Open Access Journals (Sweden)

    Tzu-Hsiang Yen, Bin-Hao Chen, Bao-Dong Chen

    2011-05-01

    Full Text Available Metal hydride reactors are widely used in many industrial applications, such as hydrogen storage, thermal compression, heat pump, etc. According to the research requirement of metal hydride hydrogen storage, the thermal analyses have been implemented in the paper. The metal hydride reaction beds are considered as coupled cylindrical tube modules which combine the chemical absorption and desorption in metal hydride. The model is then used metal hydride LaNi5 as an example to predict the performance of metal hydride hydrogen storage devices, such as the position of hydration front and the thermal flux. Under the different boundary condition the characteristics of heat transfer and mass transfer in metal hydride have influence on the hydrogen absorption and desorption. The researches revealed that the scroll design can improve the temperature distribution in the reactor and the porous tube for directing hydrogen can increase the penetration depth of hydride reaction to decrease the hydrogen absorption time.

  20. Multidimensional simulations of hydrides during fuel rod lifecycle

    Science.gov (United States)

    Stafford, D. S.

    2015-11-01

    In light water reactor fuel rods, waterside corrosion of zirconium-alloy cladding introduces hydrogen into the cladding, where it is slightly soluble. When the solubility limit is reached, the hydrogen precipitates into crystals of zirconium hydride which decrease the ductility of the cladding and may lead to cladding failure during dry storage or transportation events. The distribution of the hydride phase and the orientation of the crystals depend on the history of the spatial temperature and stress profiles in the cladding. In this work, we have expanded the existing hydride modeling capability in the BISON fuel performance code with the goal of predicting both global and local effects on the radial, azimuthal and axial distribution of the hydride phase. We compare results from 1D simulations to published experimental data. We demonstrate the new capability by simulating in 2D a fuel rod throughout a lifecycle that includes irradiation, short-term storage in the spent fuel pool, drying, and interim storage in a dry cask. Using the 2D simulations, we present qualitative predictions of the effects of the inter-pellet gap and the drying conditions on the growth of a hydride rim.

  1. Sodium-based hydrides for thermal energy applications

    Science.gov (United States)

    Sheppard, D. A.; Humphries, T. D.; Buckley, C. E.

    2016-04-01

    Concentrating solar-thermal power (CSP) with thermal energy storage (TES) represents an attractive alternative to conventional fossil fuels for base-load power generation. Sodium alanate (NaAlH4) is a well-known sodium-based complex metal hydride but, more recently, high-temperature sodium-based complex metal hydrides have been considered for TES. This review considers the current state of the art for NaH, NaMgH3- x F x , Na-based transition metal hydrides, NaBH4 and Na3AlH6 for TES and heat pumping applications. These metal hydrides have a number of advantages over other classes of heat storage materials such as high thermal energy storage capacity, low volume, relatively low cost and a wide range of operating temperatures (100 °C to more than 650 °C). Potential safety issues associated with the use of high-temperature sodium-based hydrides are also addressed.

  2. The effect of stress state on zirconium hydride reorientation

    Science.gov (United States)

    Cinbiz, Mahmut Nedim

    Prior to storage in a dry-cask facility, spent nuclear fuel must undergo a vacuum drying cycle during which the spent fuel rods are heated up to elevated temperatures of ≤ 400°C to remove moisture the canisters within the cask. As temperature increases during heating, some of the hydride particles within the cladding dissolve while the internal gas pressure in fuel rods increases generating multi-axial hoop and axial stresses in the closed-end thin-walled cladding tubes. As cool-down starts, the hydrogen in solid solution precipitates as hydride platelets, and if the multiaxial stresses are sufficiently large, the precipitating hydrides reorient from their initial circumferential orientation to radial orientation. Radial hydrides can severely embrittle the spent nuclear fuel cladding at low temperature in response to hoop stress loading. Because the cladding can experience a range of stress states during the thermo-mechanical treatment induced during vacuum drying, this study has investigated the effect of stress state on the process of hydride reorientation during controlled thermo-mechanical treatments utilizing the combination of in situ X-ray diffraction and novel mechanical testing analyzed by the combination of metallography and finite element analysis. The study used cold worked and stress relieved Zircaloy-4 sheet containing approx. 180 wt. ppm hydrogen as its material basis. The failure behavior of this material containing radial hydrides was also studied over a range of temperatures. Finally, samples from reactor-irradiated cladding tubes were examined by X-ray diffraction using synchrotron radiation. To reveal the stress state effect on hydride reorientation, the critical threshold stress to reorient hydrides was determined by designing novel mechanical test samples which produce a range of stress states from uniaxial to "near-equibiaxial" tension when a load is applied. The threshold stress was determined after thermo-mechanical treatments by

  3. Ion-beam excitation of liquid argon

    CERN Document Server

    Hofmann, M; Heindl, T; Neumeier, A; Oberauer, L; Potzel, W; Roth, S; Schönert, S; Wieser, J; Ulrich, A

    2015-01-01

    The scintillation light of liquid argon has been recorded wavelength and time resolved with very good statistics in a wavelength interval ranging from 118 nm through 970 nm. Three different ion beams, protons, sulfur ions and gold ions, were used to excite liquid argon. Only minor differences were observed in the wavelength-spectra obtained with the different incident particles. Light emission in the wavelength range of the third excimer continuum was found to be strongly suppressed in the liquid phase. In time-resolved measurements, the time structure of the scintillation light can be directly attributed to wavelength in our studies, as no wavelength shifter has been used. These measurements confirm that the singlet-to-triplet intensity ratio in the second excimer continuum range is a useful parameter for particle discrimination, which can also be employed in wavelength-integrated measurements as long as the sensitivity of the detector system does not rise steeply for wavelengths longer than 190 nm. Using ou...

  4. Argon laser-welded arteriovenous anastomoses.

    Science.gov (United States)

    White, R A; Kopchok, G; Donayre, C; White, G; Lyons, R; Fujitani, R; Klein, S R; Uitto, J

    1987-11-01

    This study compared the healing of laser-welded and sutured canine femoral arteriovenous anastomoses. Arteriovenous fistulas 2 cm in length were created bilaterally in the femoral vessels of 10 dogs and were studied at 1 (n = 2), 2 (n = 2), 4 (n = 3), and 8 (n = 3) weeks. In each animal, one anastomosis (control) was closed with running 6-0 polypropylene sutures, and the contralateral anastomosis (experimental) was sealed with an argon laser (0.5 watt, 4 minutes of exposure, 1830 J/cm2/1 cm length of anastomosis). At removal all experimental anastomoses were patent without hematomas, aneurysms, or luminal narrowing. Histologic examination at 4 weeks revealed that laser-welded anastomoses had less inflammatory response and almost normal collagen and elastin reorientation. At 8 weeks sutured anastomoses had significant intimal hyperplasia whereas laser repairs had normal luminal architecture. Tensile strength and collagen production, measured by the synthesis of hydroxyproline and the steady-state levels of type I and type III procollagen messenger ribonucleic acids, at the anastomoses and in adjacent vein and artery specimens were similar in sutured and laser-welded repairs at 2, 4, and 8 weeks. We conclude that argon laser welding of anastomoses is an acceptable alternative to suture techniques, with the advantage of improved healing without foreign body response and possible diminished intimal hyperplasia at the anastomotic line. PMID:3312648

  5. Electron scattering and transport in liquid argon

    International Nuclear Information System (INIS)

    The transport of excess electrons in liquid argon driven out of equilibrium by an applied electric field is revisited using a multi-term solution of Boltzmann’s equation together with ab initio liquid phase cross-sections calculated using the Dirac-Fock scattering equations. The calculation of liquid phase cross-sections extends previous treatments to consider multipole polarisabilities and a non-local treatment of exchange, while the accuracy of the electron-argon potential is validated through comparison of the calculated gas phase cross-sections with experiment. The results presented highlight the inadequacy of local treatments of exchange that are commonly used in liquid and cluster phase cross-section calculations. The multi-term Boltzmann equation framework accounting for coherent scattering enables the inclusion of the full anisotropy in the differential cross-section arising from the interaction and the structure factor, without an a priori assumption of quasi-isotropy in the velocity distribution function. The model, which contains no free parameters and accounts for both coherent scattering and liquid phase screening effects, was found to reproduce well the experimental drift velocities and characteristic energies

  6. Pollution of liquid argon after neutron irradiation

    CERN Document Server

    Andrieux, M L; Collot, J; de Saintignon, P; Ferrari, A; Hostachy, J Y; Hoummada, A; Martin, P; Merkel, B; Puzo, P; Sauvage, D; Wielers, M

    2001-01-01

    The purpose of the neutron facility installed at SARA is to investigate the behavior of various materials to be used in the ATLAS liquid argon calorimeter, when submitted to fast neutron radiation. The samples are placed in a liquid argon cryostat a few cm away from the neutron source. Various pieces of the electromagnetic calorimeter have been tested in order to evaluate the rate of pollution of the liquid and consequently the possible signal loss in energy measurements. The average fluence was equivalent to the maximum expected in the calorimeter in about 10 years. The most striking feature of the results is that the pollution is not due to oxygen, at least for most of it. Using a particular value of the absorption length derived from these data, a simulation was carried out and the energy signal loss in the calorimeter could be predicted. Within the limits of our present knowledge, the conclusion is that damages due to this pollution will not be a problem. (17 refs).

  7. Pollution of liquid argon after neutron irradiation

    International Nuclear Information System (INIS)

    The purpose of the neutron facility installed at SARA is to investigate the behavior of various materials to be used in the ATLAS liquid argon calorimeter, when submitted to fast neutron radiation. The samples are placed in a liquid argon cryostat a few cm away from the neutron source. Various pieces of the electromagnetic calorimeter have been tested in order to evaluate the rate of pollution of the liquid and consequently the possible signal loss in energy measurements. The average fluence was equivalent to the maximum expected in the calorimeter in about 10 years. The most striking feature of the results is that the pollution is not due to oxygen, at least for most of it. Using a particular value of the absorption length derived from these data, a simulation was carried out and the energy signal loss in the calorimeter could be predicted. Within the limits of our present knowledge, the conclusion is that damages due to this pollution will not be a problem

  8. Numerical Modeling of an RF Argon-Silane Plasma with Dust Particle Nucleation and Growth

    Science.gov (United States)

    Girshick, Steven; Agarwal, Pulkit

    2012-10-01

    We have developed a 1-D numerical model of an RF argon-silane plasma in which dust particles nucleate and grow. This model self-consistently couples a plasma module, a chemistry module and an aerosol module. The plasma module solves population balance equations for electrons and ions, the electron energy equation under the assumption of a Maxwellian velocity distribution, and Poisson's equation for the electric field. The chemistry module treats silane dissociation and reactions of silicon hydrides containing up to two silicon atoms. The aerosol module uses a sectional method to model particle size and charge distributions. The nucleation rate is equated to the rates of formation of anions containing two Si atoms, and a heterogeneous reaction model is used to model particle surface growth. Aerosol effects considered include particle charging, coagulation, and particle transport by neutral drag, ion drag, electric force, gravity and Brownian diffusion. Simulation results are shown for the case of a 13.56 MHz plasma at a pressure of 13 Pa and applied RF voltage of 100 V (amplitude), with flow through a showerhead electrode. These results show the strong coupling between the plasma and the spatiotemporal evolution of the nanoparticle cloud.

  9. High-Spin Cobalt Hydrides for Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Holland, Patrick L. [Yale University

    2013-08-29

    Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

  10. Iron Hydride Detection and Intramolecular Hydride Transfer in a Synthetic Model of Mono-Iron Hydrogenase with a CNS Chelate.

    Science.gov (United States)

    Durgaprasad, Gummadi; Xie, Zhu-Lin; Rose, Michael J

    2016-01-19

    We report the identification and reactivity of an iron hydride species in a synthetic model complex of monoiron hydrogenase. The hydride complex is derived from a phosphine-free CNS chelate that includes a Fe-C(NH)(═O) bond (carbamoyl) as a mimic of the active site iron acyl. The reaction of [((O═)C(HN)N(py)S(Me))Fe(CO)2(Br)] (1) with NaHBEt3 generates the iron hydride intermediate [((O═)C(HN)N(py)S(Me))Fe(H)(CO)2] (2; δFe-H = -5.08 ppm). Above -40 °C, the hydride species extrudes CH3S(-) via intramolecular hydride transfer, which is stoichiometrically trapped in the structurally characterized dimer μ2-(CH3S)2-[((O═)C(HN)N(Ph))Fe(CO)2]2 (3). Alternately, when activated by base ((t)BuOK), 1 undergoes desulfurization to form a cyclometalated species, [((O═)C(NH)NC(Ph))Fe(CO)2] (5); derivatization of 5 with PPh3 affords the structurally characterized species [((O═)C(NH)NC)Fe(CO)(PPh3)2] (6), indicating complex 6 as the common intermediate along each pathway of desulfurization.

  11. A new heat storage system using metal hydrides

    Science.gov (United States)

    Ono, S.; Kawamura, M.; Ishido, Y.; Akiba, E.; Higano, S.

    The development of a prototype chemical heat storage system, designed for the accumulation of fairly high temperature (300 - 400 C) waste heat, and called the Hydriding Heat Storage system is presented. Mg2Ni hydride is used as the high temperature heat storing medium, and LaNi5H6 is used as a reservoir for the hydrogen released from the heat storing medium. The system has been in development since 1976, and a 2000 kcal heat capacity prototype system is to be completed by 1982. Basic investigations, i.e., reaction kinetics of absorption and desorption, and heat transfer characteristics of the hydride and/or the metal powder packed bed, are described.

  12. Kinetic and structural aspects of tantalum hydride formation

    Directory of Open Access Journals (Sweden)

    R. DIMITRIJEVIC

    2003-09-01

    Full Text Available Tantalum hydrides of various composition were synthesized by equilibrating tantalum with hydrogen at six different temperatures from 573 to 823 K, under a constant hydrogen pressure of 1 bar. Both the exact Ta/H mole ratios and the kinetic parameters of hydriding were determined on the basis of the dependence of the H/Ta mole ratio on time. The influence of stoichiometry on the appearance of X-ray powder diffractograms at room temperature was studied. As a consequence of hydriding, for ratios H/Ta > 0.2, the original bcc Ta-lattice undergoes distortion, manifesting itself as both a shift and a splitting of the X-ray patterns in the X-ray diffractograms. For samples with H/Ta < 0.2, the appearance of some superstructure reflections at low Bragg angles was noted, which suggests a long range ordering of hydrogen with orthorhombic symmetry.

  13. Theoretical Estimate of Hydride Affinities of Aromatic Carbonyl Compounds

    Institute of Scientific and Technical Information of China (English)

    AI Teng; ZHU Xiao-Qing; CHENG Jin-Pei

    2003-01-01

    @@ Aromatic carbonyl compounds are one type of the most important organic compounds, and the reductions ofthem by hydride agents such as LiAlH4 or NaBH4 are widely used in organic synthesis. The reactivity of carbonyl compounds generally increases in the following order: ketone < aldehyde, and amide < acid < ester < acid halide, which could be related to their hydride affinities (HA). In the previous paper, Robert[1] calculated the absolute HAof a series of small non-aromatic carbonyl compounds. In this paper, we use DFT method at B3LYP/6-311 + + G (2d, 2p)∥B3LYP/6-31 + G* level to estimate hydride affinities of five groups of aromatic carbonyl compounds. The detailed results are listed in Table 1.

  14. Photoelectron spectroscopy of boron aluminum hydride cluster anions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Gantefoer, Gerd; Bowen, Kit H., E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Li, Xiang [Center for Space Science and Technology, University of Maryland–Baltimore County, Baltimore, Maryland 21250 (United States); Kiran, Boggavarapu, E-mail: kbowen@jhu.edu, E-mail: kiran@mcneese.edu [Department of Chemistry and Physics, McNeese State University, Lake Charles, Louisiana 70609 (United States); Kandalam, Anil K. [Department of Physics, West Chester University, West Chester, Pennsylvania 19383 (United States)

    2014-04-28

    Boron aluminum hydride clusters are studied through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations. Boron aluminum hydride cluster anions, B{sub x}Al{sub y}H{sub z}{sup −}, were generated in a pulsed arc cluster ionization source and identified by time-of-flight mass spectrometry. After mass selection, their photoelectron spectra were measured by a magnetic bottle-type electron energy analyzer. The resultant photoelectron spectra as well as calculations on a selected series of stoichiometries reveal significant geometrical changes upon substitution of aluminum atoms by boron atoms.

  15. Ab-initio study of transition metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Ramesh [Dept. of Physics, Feroze Gandhi Insititute of Engineering and Technology, Raebareli-229001 (India); Shukla, Seema, E-mail: sharma.yamini62@gmail.com; Dwivedi, Shalini, E-mail: sharma.yamini62@gmail.com; Sharma, Yamini, E-mail: sharma.yamini62@gmail.com [Theoretical Condensed Matter Physics Laboratory, Dept. of Physics Feroze Gandhi College, Raebareli-229001 (India)

    2014-04-24

    We have performed ab initio self consistent calculations based on Full potential linearized augmented plane wave (FP-LAPW) method to investigate the optical and thermal properties of yttrium hydrides. From the band structure and density of states, the optical absorption spectra and specific heats have been calculated. The band structure of Yttrium metal changes dramatically due to hybridization of Y sp orbitals with H s orbitals and there is a net charge transfer from metal to hydrogen site. The electrical resistivity and specific heats of yttrium hydrides are lowered but the thermal conductivity is slightly enhanced due to increase in scattering from hydrogen sites.

  16. WARP: a double phase argon programme for dark matter detection

    International Nuclear Information System (INIS)

    WARP (Wimp ARgon Programme) is a double phase Argon detector for Dark Matter search under construction at Laboratori Nazionali del Gran Sasso. We present recent results obtained operating a prototype with a sensitive mass of 2.3 litres deep underground

  17. Stopping Power of Solid Argon for Helium Ions

    DEFF Research Database (Denmark)

    Besenbacher, F.; Bøttiger, Jørgen; Grauersen, O.;

    1981-01-01

    By means of the Rutherford-backscattering method, the stopping cross section of solid argon has been measured for 0.5–3 MeV helium ions to an accuracy of not, vert, similar3%. The results agree within the experimental accuracies with our earlier measurements for gaseous argon over the energy region...

  18. Nitrogen Removal from Molten Steel under Argon DC Glow Plasma

    Institute of Scientific and Technical Information of China (English)

    SUN Ming-shan; DING Wei-zhong; LU Xiong-gang

    2005-01-01

    Under argon DC glow plasma, the nitrogen removal from molten steel was studied. The experimental result showed that nitrogen mass percent could be reduced to 0.000 8%. The change of polarity had no impact on nitrogen removal when the nitrogen mass percent was low. The mechanism of denitrogenation of molten steel under argon DC glow plasma was discussed.

  19. Comparison of Diode and Argon Laser Lesions in Rabbit Retina

    Institute of Scientific and Technical Information of China (English)

    Hui Zhang; Xiaoxin Li; Bin Li; Jiping Da

    2004-01-01

    Purpose: To compare the histological alteration of retina with various spot intensities between diode and argon lasers in order to instruct the clinical use of 810 nm diode laser.Methods: Transpupillary retinal photocoagulations were performed on 42 eyes of 27pigmented rabbits. Histopathologic alteration of lesions in different intensities and different time intervals after irradiation produced by diode and argon laser was observed and compared using light microscopy. Areas of various lesions measured by image analysis system (CMIAS) were compared quantitatively.Results: Histopathologically, two-week-old grade 2 lesions produced by diode laser induced the disappearance of outer nuclear cells. More than a half of all showed reduction in number of outer nuclear layer cells in argon. Fibroblasts appeared in the diode grade 3lesions 5 days after irradiation. CMIAS data showed that all the areas of diode lesions immediately after photocoagulation were to be larger than those of argon laser lesions in the same spot intensity (P < 0.05). However, twenty-four hours after photocoagulation, the area of the diode lesions increased less than that of the argon laser lesions (8%vs.23%).Conclusion: The acute histological effect caused by 810 nm diode laser and argon green laser is similar,while the expansion of lesion area 24 hours after photocoagulation was less with the diode laser compared to the argon. This may be the first report in the literature regarding quantitative analysis of the delayed reaction of argon green lasers.

  20. Chemical Hydride Slurry for Hydrogen Production and Storage

    Energy Technology Data Exchange (ETDEWEB)

    McClaine, Andrew W

    2008-09-30

    The purpose of this project was to investigate and evaluate the attractiveness of using a magnesium chemical hydride slurry as a hydrogen storage, delivery, and production medium for automobiles. To fully evaluate the potential for magnesium hydride slurry to act as a carrier of hydrogen, potential slurry compositions, potential hydrogen release techniques, and the processes (and their costs) that will be used to recycle the byproducts back to a high hydrogen content slurry were evaluated. A 75% MgH2 slurry was demonstrated, which was just short of the 76% goal. This slurry is pumpable and storable for months at a time at room temperature and pressure conditions and it has the consistency of paint. Two techniques were demonstrated for reacting the slurry with water to release hydrogen. The first technique was a continuous mixing process that was tested for several hours at a time and demonstrated operation without external heat addition. Further work will be required to reduce this design to a reliable, robust system. The second technique was a semi-continuous process. It was demonstrated on a 2 kWh scale. This system operated continuously and reliably for hours at a time, including starts and stops. This process could be readily reduced to practice for commercial applications. The processes and costs associated with recycling the byproducts of the water/slurry reaction were also evaluated. This included recovering and recycling the oils of the slurry, reforming the magnesium hydroxide and magnesium oxide byproduct to magnesium metal, hydriding the magnesium metal with hydrogen to form magnesium hydride, and preparing the slurry. We found that the SOM process, under development by Boston University, offers the lowest cost alternative for producing and recycling the slurry. Using the H2A framework, a total cost of production, delivery, and distribution of $4.50/kg of hydrogen delivered or $4.50/gge was determined. Experiments performed at Boston

  1. Merging of high speed argon plasma jets

    Energy Technology Data Exchange (ETDEWEB)

    Case, A.; Messer, S.; Brockington, S.; Wu, L.; Witherspoon, F. D. [HyperV Technologies Corp., Chantilly, Virginia 22180 (United States); Elton, R. [University of Maryland, College Park, Maryland 20742 (United States)

    2013-01-15

    Formation of an imploding plasma liner for the plasma liner experiment (PLX) requires individual plasma jets to merge into a quasi-spherical shell of plasma converging on the origin. Understanding dynamics of the merging process requires knowledge of the plasma phenomena involved. We present results from the study of the merging of three plasma jets in three dimensional geometry. The experiments were performed using HyperV Technologies Corp. 1 cm Minirailguns with a preionized argon plasma armature. The vacuum chamber partially reproduces the port geometry of the PLX chamber. Diagnostics include fast imaging, spectroscopy, interferometry, fast pressure probes, B-dot probes, and high speed spatially resolved photodiodes, permitting measurements of plasma density, temperature, velocity, stagnation pressure, magnetic field, and density gradients. These experimental results are compared with simulation results from the LSP 3D hybrid PIC code.

  2. Large vessel sealing with the argon laser.

    Science.gov (United States)

    White, R A; Kopchok, G; Donayre, C; Lyons, R; White, G; Klein, S R; Pizzurro, D; Abergel, R P; Dwyer, R M; Uitto, J

    1987-01-01

    This study compared the histology, biochemistry, and tensile strength of laser-welded and sutured canine venotomies, arteriotomies, and arteriovenous fistulas. Twelve animals had bilateral femoral vessels studied, with one repair (control) closed with interrupted 6-0 polypropylene sutures, and the contralateral repair (experimental) welded with the argon laser. Specimens were examined at weekly intervals from 1 to 4 weeks (four animals for each type of repair), and were evaluated histologically by hematoxylin and eosin, elastin, and trichrome stains; biochemically by the formation of [3H]hydroxyproline as an index of collagen synthesis; and mechanically by tensile strength determinations. At removal, all experimental closures were patent without hematomas, aneurysms, or luminal dilatation. Histologic and biochemical examination and tensile strength determinations suggest that laser welding may be an alternative to sutures for repair of large-diameter venotomies, arteriotomies, and arteriovenous fistulas, as healing is comparable to that seen with suture repairs up to 4 weeks postoperatively. PMID:3306233

  3. Vascular Welding Using The Argon Laser

    Science.gov (United States)

    White, Rodney A.; Donayre, Carlos; Kopchok, George; White, Geoffrey; Abergel, R. Patrick; Lyons, Richard; Klein, Stanley; Dwyer, Richard; Uitto, Jouni

    1987-03-01

    This study compared the histology, biochemistry, and tensile strength of laser welded and sutured canine venotomies, arteriotomies and arteriovenous fistulas. Bilateral femoral, carotid or jugular vessels were studied with one repair (control) closed with interrupted 6-0 polypropylene sutures, and the contralatral repair (experimental) welded with the argon laser. Specimens were examined at weekly intervals from 1 to 4 weeks for each type of repair and evaluated histologically by hematoxylineosin, elastin and trichrome stains, biochemically by the formation of [3H] hyaroxyproline as an index of collagen synthesis, ana mechanically by tensile strength determinations. At removal, all experimental closures were patent without hematomas, aneurysms or luminal dilatation. Histologic and biochemical examination and tensile strength determinations suggest that laser welaing may be an alternative to sutures for repair of large diameter venotomies, arteriotomies and arteriovenous fistulas, as they heal comparable to suture repairs up to 4 weeks postoperatively.

  4. Commissioning of the ATLAS liquid argon calorimeters

    CERN Document Server

    Rezaie, Erfan

    ATLAS, a multi-purpose detector built at the LHC at CERN, requires an extensive commissioning campaign to be ready for proton-proton collisions. In this work, we focus on the commissioning of the liquid Argon (LAr) calorimeters, with emphasis on commissioning with cosmic rays. First we outline one phase of the commissioning work, which involves testing of the front-end electronics of the two endcap calorimeters. We then describe two cosmic ray generators as input to a Monte-Carlo simulation of cosmic rays in ATLAS, and compare their results. Finally, we explain a technique developed for this work which uses information from the Tile calorimeters to predict the timing of cosmic rays within the LAr calorimeters, because cosmic rays occur randomly in time whereas the electronics are clocked at [Special characters omitted.] . The results from this analysis tool are compared to default tools, using both simulated and real cosmic ray data in the calorimeters.

  5. Comparison of irradiation hardening and microstructure evolution in ion-irradiated delta and epsilon hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Oono, Naoko, E-mail: n-oono@eng.hokudai.ac.jp [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kasada, Ryuta [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Higuchi, Toru; Sakamoto, Kan; Nakatsuka, Masafumi [Nippon Nuclear Fuel Development Co., Ltd., 2163 Naritacho Oarai, Higashi-Ibaraki, Ibaraki 311-1313 (Japan); Hasegawa, Akiko; Kondo, Sosuke; Iwata, Noriyuki Y.; Matsui, Hideki; Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2013-11-15

    A δ-Zr-hydride was irradiated with 6.4 MeV Fe{sup 3+} ions to clarify the relationship between hardening and microstructural changes of bulk Zr-hydrides under neutron irradiation. Irradiation hardening was measured by nanoindentation tests. Transmission electron microscope cross-sectional observations showed that the deformation mechanism of the δ-Zr-hydride was both slip and twinning. Dislocation loops were observed in the irradiated hydride matrix. These irradiation-induced defects make slip deformation difficult and consequently promote the twin deformation of δ-Zr-hydride. This work is a continuation of the previous our work (J. Nucl. Mater. 419 (2011) 366–370) focused upon ε-Zr-hydride and we discuss a comparison between the two Zr-hydrides.

  6. Growth and decomposition of Lithium and Lithium hydride on Nickel

    DEFF Research Database (Denmark)

    Engbæk, Jakob; Nielsen, Gunver; Nielsen, Jane Hvolbæk;

    2006-01-01

    In this paper we have investigated the deposition, structure and decomposition of lithium and lithium-hydride films on a nickel substrate. Using surface sensitive techniques it was possible to quantify the deposited Li amount, and to optimize the deposition procedure for synthesizing lithium...

  7. Process of forming a sol-gel/metal hydride composite

    Science.gov (United States)

    Congdon, James W.

    2009-03-17

    An external gelation process is described which produces granules of metal hydride particles contained within a sol-gel matrix. The resulting granules are dimensionally stable and are useful for applications such as hydrogen separation and hydrogen purification. An additional coating technique for strengthening the granules is also provided.

  8. Structural deformation of metallic uranium surrounding hydride growth sites

    International Nuclear Information System (INIS)

    Highlights: • UH3 formation on uranium surfaces by a controlled uptake of hydrogen at 240 °C. • Large hydride growths (35–125 μm in diameter) form at the surface. • Confined hydride expansion during growth generates stress in the subsurface. • EBSD scans found micro-cracking and twins as forms of stress relief in the metal. - Abstract: Electron backscatter diffraction (EBSD) was utilised to probe the microstructure of uranium metal in the vicinity of surface corrosion pits, resulting from hydrogen exposure (5 × 104 Pa, at 240 °C). Microstructural analysis of the surface revealed a subtle increase of grain orientation variation for grains at the border of the hydride growths. Cross sectional analysis, at pit sites, revealed significant microstructure deformation in the form of crystal twinning and micro-cracking beneath the surface. These observations provide qualitative evidence that local stress intensities generated as a consequence of hydride growth and confinement, were sufficient to cause deformation within the parent metal

  9. Design and integration of a hydrogen storage on metallic hydrides

    International Nuclear Information System (INIS)

    This work presents a hydrogen storage system using metal hydrides for a Combined Heat and Power (CHP) system. Hydride storage technology has been chosen due to project specifications: high volumetric capacity, low pressures (≤ 3.5 bar) and low temperatures (≤ 75 C: fuel cell temperature). During absorption, heat from hydride generation is dissipated by fluid circulation. An integrated plate-fin type heat exchanger has been designed to obtain good compactness and to reach high absorption/desorption rates. At first, the storage system has been tested in accordance with project specifications (absorption 3.5 bar, desorption 1.5 bar). Then, the hydrogen charge/discharge times have been decreased to reach system limits. System design has been used to simulate thermal and mass comportment of the storage tank. The model is based on the software Fluent. We take in consideration heat and mass transfers in the porous media during absorption/desorption. The hydride thermal and mass behaviour has been integrated in the software. The heat and mass transfers experimentally obtained have been compared to results calculated by the model. The influence of experimental and numerical parameters on the model behaviour has also been explored. (author)

  10. Diffusion model of delayed hydride cracking in zirconium alloys

    NARCIS (Netherlands)

    Shmakov, AA; Kalin, BA; Matvienko, YG; Singh, RN; De, PK

    2004-01-01

    We develop a method for the evaluation of the rate of delayed hydride cracking in zirconium alloys. The model is based on the stationary solution of the phenomenological diffusion equation and the detailed analysis of the distribution of hydrostatic stresses in the plane of a sharp tensile crack. Th

  11. Electrochromism of Mg-Ni hydride switchable mirrors

    Science.gov (United States)

    Isidorsson, Jan; Giebels, I. A. M. E.; Di Vece, M.; Griessen, Ronald

    2001-11-01

    Switchable mirrors have so far been made of rare-earth and rare-earth-magnesium based metal-hydrides. In this investigation we study Mg-Ni-hydrides, which have been shown by Richardson et al. to exhibit switchable properties similar to those of the rare-earth hydrides. Cyclic voltammetry on MgzNiHx samples with 0.8 less than z less than 3.7 shows that addition of one Mg atom per Mg2Ni gives the best ab/desorption kinetics for hydrogen. X- ray diffraction reveals a structural change as hydrogen is absorbed. The metal-insulator transition is confirmed with simultaneous resistivity measurements. A pressure- composition isotherm of Mg2NiHx is also determined electrochemically. Optical spectrometry during gas loading gives an optical band gap of 1.6 eV for Mg2NiH4. This gap increases with increasing Mg content in a way similar to that of the Mg-doped rare-earth hydrides.

  12. Hydrogen Storage in Porous Materials and Magnesium Hydrides

    NARCIS (Netherlands)

    Grzech, A.

    2013-01-01

    In this thesis representatives of two different types of materials for potential hydrogen storage application are presented. Usage of either nanoporous materials or metal hydrides has both operational advantages and disadvantages. A main objective of this thesis is to characterize the hydrogen stora

  13. Hydriding/dehydriding behavior of Mg{sub 2}CoH{sub 5} produced by reactive mechanical milling

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, I. Gonzalez [Instituto Balseiro, U.N. Cuyo (Argentina); Meyer, G.O. [Instituto Balseiro, U.N. Cuyo (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, CONICET (Argentina); Centro Atomico Bariloche (CNEA), R8402AGP, S.C. de Bariloche (Argentina); Gennari, F.C. [Instituto Balseiro, U.N. Cuyo (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, CONICET (Argentina); Centro Atomico Bariloche (CNEA), R8402AGP, S.C. de Bariloche (Argentina)], E-mail: gennari@cab.cnea.gov.ar

    2008-09-22

    Complex Mg{sub 2}CoH{sub 5} hydride was obtained by a combined procedure that included a milling stage of a 2Mg-Co mixture under argon followed by reactive mechanical alloying (RMA) under hydrogen, both at room temperature. During RMA, MgH{sub 2} is produced at short milling times (10 h) and Mg{sub 2}CoH{sub 5} (50 wt%) after 90 h. Improvement in the yield and the formation times could be associated with both refinement of microstructure and enhancement of intermixing of Mg-Co during pre-milling stage. DSC studies of Mg{sub 2}CoH{sub 5} phase produced by RMA show that the starting decomposition temperature is about 205 deg. C. Absorption and desorption PCIs were determined under static (300 deg. C) and dynamic (230-330 deg. C) conditions. An important hysteresis and two plateaus were observed and correlated with formation/decomposition of Mg{sub 2}CoH{sub 5} (high-pressure plateau) and Mg{sub 6}Co{sub 2}H{sub 11} (low-pressure plateau) hydrides. For comparing hydrogen sorption kinetics, Mg{sub 2}CoH{sub 5} (65 wt%) was also obtained by a sintering method at 410 deg. C and 6.0 MPa of hydrogen pressure. Absorption was very fast in the temperature range of 150-350 deg. C, independently of synthesis procedure. However, desorption curves showed a better behavior for RMA powders. MgCo was observed after decomposition of Mg{sub 2}CoH{sub 5} under particular thermal treatments, while MgCo{sub 2} phase was not detected. The results of this study reinforce the idea that kinetics factors related with atomic mobility play a key role in the formation of Mg-Co intermetallics.

  14. Argon laser induced changes to the carbonate content of enamel

    International Nuclear Information System (INIS)

    Argon laser irradiation can be used to cure orthodontic brackets onto teeth in significantly less time than conventional curing lights. In addition, it has been shown that the argon laser seems to impart a demineralization resistance to the enamel. The purpose of this study was to use surface science techniques to ascertain if this demineralization resistance is possibly a result of a decrease in the carbonate content of enamel. Eleven mandibular third molars previously scheduled for extraction were collected and used in the present study. The teeth were sectioned in two and randomly assigned to either the argon laser (457-502 nm; 250 mW cm-2) or the control (no treatment) group. The sections assigned to the argon laser group were cured for 10 s and analyzed. To exaggerate any potential changes the experimental sections were then exposed to a further 110 s of argon laser irradiation. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed no statistically significant change in the carbonate content of enamel after argon laser irradiation (p > 0.05). Thus, it is suggested that any demineralization resistance imparted to the enamel surface by argon laser irradiation is not due to alterations in carbonate content.

  15. Synthesis of hydrides by interaction of intermetallic compounds with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Tarasov, Boris P., E-mail: tarasov@icp.ac.ru [Institute of Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Fokin, Valentin N.; Fokina, Evelina E. [Institute of Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka 142432 (Russian Federation); Yartys, Volodymyr A., E-mail: volodymyr.yartys@ife.no [Institute for Energy Technology, Kjeller NO 2027 (Norway); Department of Materials Science and Engineering, Norwegian University of Science and Technology, Trondheim NO 7491 (Norway)

    2015-10-05

    Highlights: • Interaction of the intermetallics A{sub 2}B, AB, AB{sub 2}, AB{sub 5} and A{sub 2}B{sub 17} with NH{sub 3} was studied. • The mechanism of interaction of the alloys with ammonia is temperature-dependent. • Hydrides, hydridonitrides, disproportionation products or metal–N–H compounds are formed. • NH{sub 4}Cl was used as an activator of the reaction between ammonia and intermetallics. • Interaction with ammonia results in the synthesis of the nanopowders. - Abstract: Interaction of intermetallic compounds with ammonia was studied as a processing route to synthesize hydrides and hydridonitrides of intermetallic compounds having various stoichiometries and types of crystal structures, including A{sub 2}B, AB, AB{sub 2}, AB{sub 5} and A{sub 2}B{sub 17} (A = Mg, Ti, Zr, Sc, Nd, Sm; B = transition metals, including Fe, Co, Ni, Ti and nontransition elements, Al and B). In presence of NH{sub 4}Cl used as an activator of the reaction between ammonia and intermetallic alloys, their interaction proceeds at rather mild P–T conditions, at temperatures 100–200 °C and at pressures of 0.6–0.8 MPa. The mechanism of interaction of the alloys with ammonia appears to be temperature-dependent and, following a rise of the interaction temperature, it leads to the formation of interstitial hydrides; interstitial hydridonitrides; disproportionation products (binary hydride; new intermetallic hydrides and binary nitrides) or new metal–nitrogen–hydrogen compounds like magnesium amide Mg(NH{sub 2}){sub 2}. The interaction results in the synthesis of the nanopowders where hydrogen and nitrogen atoms become incorporated into the crystal lattices of the intermetallic alloys. The nitrogenated materials have the smallest particle size, down to 40 nm, and a specific surface area close to 20 m{sup 2}/g.

  16. LArGe - A liquid argon scintillation veto for GERDA

    OpenAIRE

    Heisel, M.(Max-Planck-Institut für Kernphysik, Heidelberg, Germany)

    2011-01-01

    LArGe is a Gerda low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the Gerda experiment. Gerda searches for the neutrinoless double-beta decay in 76Ge, by operating naked germanium detectors submersed into 65 m3 of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m3 (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used...

  17. Practical reactor production of {sup 41}Ar from argon clathrate

    Energy Technology Data Exchange (ETDEWEB)

    Mercer, J.R. E-mail: jmercer@pharmacy.ualberta.ca; Duke, M.J.M.; McQuarrie, S.A

    2000-06-01

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

  18. Composite Materials for Hazard Mitigation of Reactive Metal Hydrides.

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, Joseph William; Cordaro, Joseph Gabriel; Sartor, George B.; Dedrick, Daniel E.; Reeder, Craig L.

    2012-02-01

    In an attempt to mitigate the hazards associated with storing large quantities of reactive metal hydrides, polymer composite materials were synthesized and tested under simulated usage and accident conditions. The composites were made by polymerizing vinyl monomers using free-radical polymerization chemistry, in the presence of the metal hydride. Composites with vinyl-containing siloxane oligomers were also polymerized with and without added styrene and divinyl benzene. Hydrogen capacity measurements revealed that addition of the polymer to the metal hydride reduced the inherent hydrogen storage capacity of the material. The composites were found to be initially effective at reducing the amount of heat released during oxidation. However, upon cycling the composites, the mitigating behavior was lost. While the polymer composites we investigated have mitigating potential and are physically robust, they undergo a chemical change upon cycling that makes them subsequently ineffective at mitigating heat release upon oxidation of the metal hydride. Acknowledgements The authors would like to thank the following people who participated in this project: Ned Stetson (U.S. Department of Energy) for sponsorship and support of the project. Ken Stewart (Sandia) for building the flow-through calorimeter and cycling test stations. Isidro Ruvalcaba, Jr. (Sandia) for qualitative experiments on the interaction of sodium alanate with water. Terry Johnson (Sandia) for sharing his expertise and knowledge of metal hydrides, and sodium alanate in particular. Marcina Moreno (Sandia) for programmatic assistance. John Khalil (United Technologies Research Corp) for insight into the hazards of reactive metal hydrides and real-world accident scenario experiments. Summary In an attempt to mitigate and/or manage hazards associated with storing bulk quantities of reactive metal hydrides, polymer composite materials (a mixture of a mitigating polymer and a metal hydride) were synthesized and tested

  19. The Effects of Dissolved Methane upon Liquid Argon Scintillation Light

    CERN Document Server

    Jones, B J P; Back, H O; Collin, G; Conrad, J M; Greene, A; Katori, T; Pordes, S; Toups, M

    2013-01-01

    In this paper we report on measurements of the effects of dissolved methane upon argon scintillation light. We monitor the light yield from an alpha source held 20 cm from a cryogenic photomultiplier tube (PMT) assembly as methane is injected into a high-purity liquid argon volume. We observe significant suppression of the scintillation light yield by dissolved methane at the 10 part per billion (ppb) level. By examining the late scintillation light time constant, we determine that this loss is caused by an absorption process and also see some evidence of methane-induced scintillation quenching at higher concentrations (50-100 ppb). Using a second PMT assembly we look for visible re-emission features from the dissolved methane which have been reported in gas-phase argon methane mixtures, and we find no evidence of visible re-emission from liquid-phase argon methane mixtures at concentrations between 10 ppb and 0.1%.

  20. Evidence of electric breakdown induced by bubbles in liquid argon

    CERN Document Server

    Bay, F; Murphy, S; Resnati, F; Rubbia, A; Sergiampietri, F; Wu, S

    2014-01-01

    We report on the results of a high voltage test in liquid argon in order to measure its dielectric rigidity. Under stable conditions and below the boiling point, liquid argon was found to sustain a uniform electric field of 100 kV/cm, applied in a region of 20 cm$^2$ area across 1 cm thick gap. When the liquid is boiling, breakdowns may occur at electric fields as low as 40 kV/cm. This test is one of the R&D efforts towards the Giant Liquid Argon Charge Imaging ExpeRiment (GLACIER) as proposed Liquid Argon Time Projection Chamber (LAr TPC) for the LBNO observatory for neutrino physics, astrophysics and nucleon decay searches.

  1. A purity monitoring system for liquid argon calorimeters

    International Nuclear Information System (INIS)

    For liquid argon calorimeters electronegative impurities dissolved in the medium degrade the detector response and deteriorate the energy resolution, especially at high energies. A concept for a purity monitoring system for liquid argon calorimeters has been developed and is presented here. Special combined monitors of 241Am- and 207Bi-cells are used to monitor the concentration of impurities. The working principle as well as results from test measurements are discussed

  2. Size Determination of Argon Clusters from a Rayleigh Scattering Experiment

    Institute of Scientific and Technical Information of China (English)

    LEI An-Le; ZHAI Hua-Jin; LIU Bing-Chen; LI Zhong; NI Guo-Yuan; XU Zhi-Zhan

    2000-01-01

    Argon clusters are produced in the process of adiabatic expansion of a high backing pressure gas into vacuum through a nozzle. The cluster size is determined by a Rayleigh scattering measurement. The scattered signal measured is proportional to the 2.78th power of gas stagnation pressure. The average cluster sizes vary from 100 to more than 12000 atoms/cluster with the argon gas backing pressures ranging between 3 to 45 atm.

  3. Pulse shape discrimination studies in a liquid Argon scintillation detector

    OpenAIRE

    Pollmann, T.

    2007-01-01

    Liquid rare gases have been gaining popularity as detector media in rare event searches, especially dark matter experiments, and one factor driving their adoption is the possibility to recognise different types of ionizing radiation by the pulse shapes they evoke. This work on pulse shape discrimination in a liquid argon scintillation detector was done in the framework of the GERDA experiment, where liquid argon scintillation signals may be used for background suppression purposes. Liquid arg...

  4. Power Consideration for Pulsed Discharges in Potassium Seeded Argon

    Institute of Scientific and Technical Information of China (English)

    XIA Sheng-Guo; HE Jun-Jia; LIU Ke-Fu

    2007-01-01

    Minimization of energy consumed in plasma generation is critical for applications, in which a large volume of plasmas is needed. We suggest that a high electron density atmospheric pressure plasmas can be generated by pulsed discharges in potassium seeded argon at an elevated temperature with a very small power input. The ionization efficiency and power budget of pulsed discharges in such plasmas are analytically studied. The results show that ionization efficiency of argon, especially at small reduced electric field E/N (the ratio of the electric field to the gas number density), is improved effectively in the presence of small amount of potassium additives. Power input of pulsed discharge to sustain a prescribed average level of ionization in potassium seeded argon is three orders of magnitude lower than that in pure argon. Further, unlike in pure argon, it is found that very short high-voltage pulses with very high repetition rates are unnecessary in potassium seeded argon. A pulse with 100ns of pulse duration, 5kHz of repetition rate, and 2Td (1 Td = 1 ×10-21 Vm2) of E/N is enough to sustain an electron density of 10l9m-3 in 1 atm 1500 K Ar+0.1% K mixture, with a very small power input of about 0.08 × 104 W/m3.

  5. Energy resolution for α-particles in doped liquid argon

    International Nuclear Information System (INIS)

    The report describes experiments on the effect of allene doped in liquid argon. In the case of doped argon, a large amount of charge is obtained even at low electric fields and the measured charge increases with the field gradually. This can be explained as follows; part of deposited energy which does not form charge in pure argon contributes to charge signal in doped argon through scintillation photons which ionize allene molecules. The main factors determining the energy resolution for α-particles are considered to be (1) fluctuation in the number of produced ion-electron pairs as expressed by the Fano factor, (2) fluctuation in recombination process, (3) fluctuation in photoionization, (4) fluctuation due to the condition of radioactive source and surface of electrodes, (5) fluctuation in geometrical efficiency due to the range and emission angle of α-particles in liquid argon, and (6) electronic noise of amplifier. The factors (1) and (3) can be neglected because of a large number of associated electrons or photons. In pure liquid argon, the factor (2) may be a cause of bad resolution since the fraction of the produced ion-electron paris which do not recombine is small and the photoionization process never occurs for photons emitted through recombination. (N.K.)

  6. Effects of metastability on hydrogen sorption in fluorine substituted hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Pinatel, E.R.; Corno, M.; Ugliengo, P.; Baricco, M., E-mail: marcello.baricco@unito.it

    2014-12-05

    Highlights: • Fluorine substitution in simple metal hydrides has been modelled. • The stability of the MH{sub (1−x)}F{sub x} solid solutions has been discussed. • Conditions for reversibility of sorption reactions have been suggested. - Abstract: In this work ab initio calculations and Calphad modelling have been coupled to describe the effect of fluorine substitution on the thermodynamics of hydrogenation–dehydrogenation in simple hydrides (NaH, AlH{sub 3} and CaH{sub 2}). These example systems have been used to discuss the conditions required for the formation of a stable hydride–fluoride solid solution necessary to obtain a reversible hydrogenation reaction.

  7. X-ray photoemission spectroscopy study of zirconium hydride

    International Nuclear Information System (INIS)

    X-ray photoemission spectroscopy (XPS) measurements are reported for ZrH/sub 1.65/ and Zr metal. The valence-band measurements are compared with available band-theory density-of-states calculations for the metal and hydride. The hydride spectrum differs significantly from the metal spectrum. Most important, a strong peak associated with hydrogen s electrons appears approximately 7 eV below the Fermi level. XPS measurements of Zr 4p core levels show a binding-energy shift of 1 eV between Zr metal and ZrH/sub 1.65/. It is argued that this shift results from charge readjustment in the vicinity of the Zr site. With the addition of hydrogen, net charge must be transferred from the Zr site to the hydrogen site. A charge-density analysis based on simplified cluster calculations is presented

  8. FEASIBILITY OF RECYCLING PLUTONIUM AND MINOR ACTINIDES IN LIGHT WATER REACTORS USING HYDRIDE FUEL

    International Nuclear Information System (INIS)

    The objective of this DOE NERI program sponsored project was to assess the feasibility of improving the plutonium (Pu) and minor actinide (MA) recycling capabilities of pressurized water reactors (PWRs) by using hydride instead of oxide fuels. There are four general parts to this assessment: (1) Identifying promising hydride fuel assembly designs for recycling Pu and MAs in PWRs; (2) Performing a comprehensive systems analysis that compares the fuel cycle characteristics of Pu and MA recycling in PWRs using the promising hydride fuel assembly designs identified in Part 1 versus using oxide fuel assembly designs; (3) Conducting a safety analysis to assess the likelihood of licensing hydride fuel assembly designs; and (4) Assessing the compatibility of hydride fuel with cladding materials and water under typical PWR operating conditions Hydride fuel was found to offer promising transmutation characteristics and is recommended for further examination as a possible preferred option for recycling plutonium in PWRs

  9. FEASIBILITY OF RECYCLING PLUTONIUM AND MINOR ACTINIDES IN LIGHT WATER REACTORS USING HYDRIDE FUEL

    Energy Technology Data Exchange (ETDEWEB)

    Greenspan, Ehud; Todreas, Neil; Taiwo, Temitope

    2009-03-10

    The objective of this DOE NERI program sponsored project was to assess the feasibility of improving the plutonium (Pu) and minor actinide (MA) recycling capabilities of pressurized water reactors (PWRs) by using hydride instead of oxide fuels. There are four general parts to this assessment: 1) Identifying promising hydride fuel assembly designs for recycling Pu and MAs in PWRs 2) Performing a comprehensive systems analysis that compares the fuel cycle characteristics of Pu and MA recycling in PWRs using the promising hydride fuel assembly designs identified in Part 1 versus using oxide fuel assembly designs 3) Conducting a safety analysis to assess the likelihood of licensing hydride fuel assembly designs 4) Assessing the compatibility of hydride fuel with cladding materials and water under typical PWR operating conditions Hydride fuel was found to offer promising transmutation characteristics and is recommended for further examination as a possible preferred option for recycling plutonium in PWRs.

  10. Effect of thermo-mechanical cycling on zirconium hydride reorientation studied in situ with synchrotron X-ray diffraction

    Science.gov (United States)

    Colas, Kimberly B.; Motta, Arthur T.; Daymond, Mark R.; Almer, Jonathan D.

    2013-09-01

    The circumferential hydrides normally present in nuclear reactor fuel cladding after reactor exposure may dissolve during drying for dry storage and re-precipitate when cooled under load into a more radial orientation, which could embrittle the fuel cladding. It is necessary to study the rates and conditions under which hydride reorientation may happen in order to assess fuel integrity in dry storage. The objective of this work is to study the effect of applied stress and thermal cycling on the hydride morphology in cold-worked stress-relieved Zircaloy-4 by combining conventional metallography and in situ X-ray diffraction techniques. Metallography is used to study the evolution of hydride morphology after several thermo-mechanical cycles. In situ X-ray diffraction performed at the Advanced Photon Source synchrotron provides real-time information on the process of hydride dissolution and precipitation under stress during several thermal cycles. The detailed study of diffracted intensity, peak position and full-width at half-maximum provides information on precipitation kinetics, elastic strains and other characteristics of the hydride precipitation process. The results show that thermo-mechanical cycling significantly increases the radial hydride fraction as well as the hydride length and connectivity. The radial hydrides are observed to precipitate at a lower temperature than circumferential hydrides. Variations in the magnitude and range of hydride strains due to reorientation and cycling have also been observed. These results are discussed in light of existing models and experiments on hydride reorientation. The study of hydride elastic strains during precipitation shows marked differences between circumferential and radial hydrides, which can be used to investigate the reorientation process. Cycling under stress above the threshold stress for reorientation drastically increases both the reoriented hydride fraction and the hydride size. The reoriented hydride

  11. Inelastic neutron scattering from amorphous hydride of Zr2Pd

    International Nuclear Information System (INIS)

    Time-of-flight inelastic neutron scattering data was obtained on hydrided Zr2Pd metallic glass using the Crystal Analyzer Spectrometer at the Los Alamos pulsed spallation neutron source. Energy transfers from about 40 MeV to several hundred MeV were obtained with sufficiently good statistics and signal to noise ratio to show the second harmonic as well as the fundamental hydrogen optic mode

  12. Proximity breakdown of hydrides in superconducting niobium cavities

    OpenAIRE

    Romanenko, A.; Barkov, F.; Cooley, L. D.; Grassellino, A.

    2012-01-01

    Many modern and proposed future particle accelerators rely on superconducting radio frequency cavities made of bulk niobium as primary particle accelerating structures. Such cavities suffer from the anomalous field dependence of their quality factors Q0. High field degradation - so-called high field Q-slope - is yet unexplained even though an empirical cure is known. Here we propose a mechanism based on the presence of proximity-coupled niobium hydrides, which can explain this effect. Further...

  13. METHOD OF MAKING DELTA ZIRCONIUM HYDRIDE MONOLITHIC MODERATOR PIECES

    Science.gov (United States)

    Vetrano, J.B.

    1962-01-23

    A method is given for preparing large, sound bodies of delta zirconium hydride. The method includes the steps of heating a zirconium body to a temperature of not less than l000 deg C, providing a hydrogen atmosphere for the zirconium body at a pressure not greater than one atmosphere, reducing the temperature slowly to 800 deg C at such a rate that cracks do not form while maintaining the hydrogen pressure substantially constant, and cooling in an atmosphere of hydrogen. (AEC)

  14. Hydrogen storage materials and metal hydride-Ni batteries

    International Nuclear Information System (INIS)

    The hydrogen storage alloy is the key active material in metal hydride-Ni (MH-Ni) batteries. A brief review of hydrogen storage negative electrode materials including misch-nickel-based alloys, Laves phase alloys, magnesium-based alloys, vanadium-based solid solutions and nanotubes is presented. Current problems that need to be solved are mentioned. In addition, recent developments of MH/Ni-batteries with high power and energy are introduced

  15. Oxidation of Group 8 transition-Metal Hydrides and Ionic Hydrogenation of Ketones and Aldehydes

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Kjell-Tore

    1996-08-01

    Transition-metal hydrides have received considerable attention during the last decades because of their unusual reactivity and their potential as homogeneous catalysts for hydrogenation and other reactions of organic substrates. An important class of catalytic processes where transition-metal hydrides are involved is the homogeneous hydrogenation of alkenes, alkynes, ketones, aldehydes, arenes and nitro compounds. This thesis studies the oxidation of Group 8 transition-metal hydrides and the ionic hydrogenation of ketones and aldehydes.

  16. Another Look at the Mechanisms of Hydride Transfer Enzymes with Quantum and Classical Transition Path Sampling

    OpenAIRE

    Dzierlenga, Michael W.; Antoniou, Dimitri; Schwartz, Steven D.

    2015-01-01

    The mechanisms involved in enzymatic hydride transfer have been studied for years, but questions remain due, in part, to the difficulty of probing the effects of protein motion and hydrogen tunneling. In this study, we use transition path sampling (TPS) with normal mode centroid molecular dynamics (CMD) to calculate the barrier to hydride transfer in yeast alcohol dehydrogenase (YADH) and human heart lactate dehydrogenase (LDH). Calculation of the work applied to the hydride allowed for obser...

  17. High Temperature Metal Hydrides as Heat Storage Materials for Solar and Related Applications

    Directory of Open Access Journals (Sweden)

    Borislav Bogdanović

    2009-01-01

    Full Text Available For the continuous production of electricity with solar heat power plants the storage of heat at a temperature level around 400 °C is essential. High temperature metal hydrides offer high heat storage capacities around this temperature. Based on Mg-compounds, these hydrides are in principle low-cost materials with excellent cycling stability. Relevant properties of these hydrides and their possible applications as heat storage materials are described.

  18. High Temperature Metal Hydrides as Heat Storage Materials for Solar and Related Applications

    OpenAIRE

    Borislav Bogdanović; Michael Felderhoff

    2009-01-01

    For the continuous production of electricity with solar heat power plants the storage of heat at a temperature level around 400 °C is essential. High temperature metal hydrides offer high heat storage capacities around this temperature. Based on Mg-compounds, these hydrides are in principle low-cost materials with excellent cycling stability. Relevant properties of these hydrides and their possible applications as heat storage materials are described.

  19. Synthesis of Renewable Energy Materials, Sodium Aluminum Hydride by Grignard Reagent of Al

    OpenAIRE

    Jun-qin Wang; Jian-feng Gao; Zhi-gang Wu; Guo-li Ou; Yu Wang

    2015-01-01

    The research on hydrogen generation and application has attracted widespread attention around the world. This paper is to demonstrate that sodium aluminum hydride can be synthesized under simple and mild reaction condition. Being activated through organics, aluminum powder reacts with hydrogen and sodium hydride to produce sodium aluminum hydride under atmospheric pressure. The properties and composition of the sample were characterized by FTIR, XRD, SEM, and so forth. The results showed that...

  20. Superconductivity of novel tin hydrides (SnnHm) under pressure

    Science.gov (United States)

    Mahdi Davari Esfahani, M.; Wang, Zhenhai; Oganov, Artem R.; Dong, Huafeng; Zhu, Qiang; Wang, Shengnan; Rakitin, Maksim S.; Zhou, Xiang-Feng

    2016-01-01

    With the motivation of discovering high-temperature superconductors, evolutionary algorithm USPEX is employed to search for all stable compounds in the Sn-H system. In addition to the traditional SnH4, new hydrides SnH8, SnH12 and SnH14 are found to be thermodynamically stable at high pressure. Dynamical stability and superconductivity of tin hydrides are systematically investigated. Im2-SnH8, C2/m-SnH12 and C2/m-SnH14 exhibit higher superconducting transition temperatures of 81, 93 and 97 K compared to the traditional compound SnH4 with Tc of 52 K at 200 GPa. An interesting bent H3–group in Im2-SnH8 and novel linear H in C2/m-SnH12 are observed. All the new tin hydrides remain metallic over their predicted range of stability. The intermediate-frequency wagging and bending vibrations have more contribution to electron-phonon coupling parameter than high-frequency stretching vibrations of H2 and H3. PMID:26964636

  1. Multidimensional Chemical Modeling. III. Abundance and excitation of diatomic hydrides

    CERN Document Server

    Bruderer, Simon; Stäuber, P; Doty, Steven D

    2010-01-01

    The Herschel Space Observatory opens the sky for observations in the far infrared at high spectral and spatial resolution. A particular class of molecules will be directly observable; light diatomic hydrides and their ions (CH, OH, SH, NH, CH+, OH+, SH+, NH+). These simple constituents are important both for the chemical evolution of the region and as tracers of high-energy radiation. If outflows of a forming star erode cavities in the envelope, protostellar far UV (FUV; 6 100 K) for water ice to evaporate. If the cavity shape allows FUV radiation to penetrate this hot-core region, the abundance of FUV destroyed species (e.g. water) is decreased. In particular, diatomic hydrides and their ions CH$+, OH+ and NH+ are enhanced by many orders of magnitude in the outflow walls due to the combination of high gas temperatures and rapid photodissociation of more saturated species. The enhancement of these diatomic hydrides is sufficient for a detection using the HIFI and PACS instruments onboard Herschel. The effect...

  2. Pressure-driven formation and stabilization of superconductive chromium hydrides

    Science.gov (United States)

    Yu, Shuyin; Jia, Xiaojing; Frapper, Gilles; Li, Duan; Oganov, Artem R.; Zeng, Qingfeng; Zhang, Litong

    2015-01-01

    Chromium hydride is a prototype stoichiometric transition metal hydride. The phase diagram of Cr-H system at high pressures remains largely unexplored due to the challenges in dealing with the high activation barriers and complications in handing hydrogen under pressure. We have performed an extensive structural study on Cr-H system at pressure range 0 ∼ 300 GPa using an unbiased structure prediction method based on evolutionary algorithm. Upon compression, a number of hydrides are predicted to become stable in the excess hydrogen environment and these have compositions of Cr2Hn (n = 2–4, 6, 8, 16). Cr2H3, CrH2 and Cr2H5 structures are versions of the perfect anti-NiAs-type CrH with ordered tetrahedral interstitial sites filled by H atoms. CrH3 and CrH4 exhibit host-guest structural characteristics. In CrH8, H2 units are also identified. Our study unravels that CrH is a superconductor at atmospheric pressure with an estimated transition temperature (T c) of 10.6 K, and superconductivity in CrH3 is enhanced by the metallic hydrogen sublattice with T c of 37.1 K at 81 GPa, very similar to the extensively studied MgB2. PMID:26626579

  3. Performance study of a hydrogen powered metal hydride actuator

    Science.gov (United States)

    Mainul Hossain Bhuiya, Md; Kim, Kwang J.

    2016-04-01

    A thermally driven hydrogen powered actuator integrating metal hydride hydrogen storage reactor, which is compact, noiseless, and able to generate smooth actuation, is presented in this article. To test the plausibility of a thermally driven actuator, a conventional piston type actuator was integrated with LaNi5 based hydrogen storage system. Copper encapsulation followed by compaction of particles into pellets, were adopted to improve overall thermal conductivity of the reactor. The operation of the actuator was thoroughly investigated for an array of operating temperature ranges. Temperature swing of the hydride reactor triggering smooth and noiseless actuation over several operating temperature ranges were monitored for quantification of actuator efficiency. Overall, the actuator generated smooth and consistent strokes during repeated cycles of operation. The efficiency of the actuator was found to be as high as 13.36% for operating a temperature range of 20 °C-50 °C. Stress-strain characteristics, actuation hysteresis etc were studied experimentally. Comparison of stress-strain characteristics of the proposed actuator with traditional actuators, artificial muscles and so on was made. The study suggests that design modification and use of high pressure hydride may enhance the performance and broaden the application horizon of the proposed actuator in future.

  4. New argon-argon (40Ar/39Ar) radiometric age dates from selected subsurface basalt flows at the Idaho National Laboratory, Idaho

    Science.gov (United States)

    Hodges, Mary K.; Turrin, Brent D.; Champion, Duane E.; Swisher, Carl C.

    2015-01-01

    In 2011, the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, collected samples for 12 new argon-argon radiometric ages from eastern Snake River Plain olivine tholeiite basalt flows in the subsurface at the Idaho National Laboratory. The core samples were collected from flows that had previously published paleomagnetic data. Samples were sent to Rutgers University for argon-argon radiometric dating analyses.

  5. Effect of the hydrogen content and cooling velocity in the hydrides precipitation in α-zirconium

    International Nuclear Information System (INIS)

    Zirconium specimens containing 50-300 ppm hydrogen have been cooled from the hydrogen solution treatment temperature at different rates by furnace cooling, air cooling and oil quenching. Optical and electron microscopical investigations have revealed grain boundary Δ - hydrides in slowly cooled specimens. At higher cooling rates γ and Δ hydrides have been found precipitated both intergranularly and intragranularly. Grain boundary Δ hydrides have been also observed in oil quenched specimens with 300 ppm hydrogen. Quenched specimens have revealed Widmanstatten and parallel plate type hydride morphologies. (Author)

  6. Synthesis of Renewable Energy Materials, Sodium Aluminum Hydride by Grignard Reagent of Al

    Directory of Open Access Journals (Sweden)

    Jun-qin Wang

    2015-01-01

    Full Text Available The research on hydrogen generation and application has attracted widespread attention around the world. This paper is to demonstrate that sodium aluminum hydride can be synthesized under simple and mild reaction condition. Being activated through organics, aluminum powder reacts with hydrogen and sodium hydride to produce sodium aluminum hydride under atmospheric pressure. The properties and composition of the sample were characterized by FTIR, XRD, SEM, and so forth. The results showed that the product through this synthesis method is sodium aluminum hydride, and it has higher purity, perfect crystal character, better stability, and good hydrogen storage property. The reaction mechanism is also discussed in detail.

  7. Evolution of Martian atmospheric argon: Implications for sources of volatiles

    Science.gov (United States)

    Hutchins, Kevin S.; Jakosky, Bruce M.

    We have examined processes affecting isotopes of argon (36Ar, 38Ar, 40Ar) in order to determine important atmospheric sources and sinks. Our simple model for argon evolution incorporates production of radiogenic argon in the mantle, outgassing of all argon species by extrusive and intrusive volcanism, and loss to space by knock-on sputtering above the exobase. Sputtering has been shown previously to be an important loss process for atmospheric species, especially isotopes of noble gases, which have few other mechanisms of escape. The integrated evolution of argon (36Ar, 38Ar, and 40Ar, respectively) is modeled in terms of these variables: (1) the planetary concentration of potassium, (2) the fraction of juvenile argon released catastrophically during the first 600 Myr., (3) potential variation in the time-history of sputtering loss from that suggested by Luhmann et al. [1992], and (4) the volume of total outgassing to the surface as compared to outgassing contributed by volcanic release. Our results indicate that Mars has lost between 85-95% of 36Ar and 70-88% of outgassed 40Ar. Due to this substantial loss, the planet must have outgassed the equivalent of between 10 and 100 times the total volume of gases released by extrusive and intrusive volcanics. This indicates that volcanic outgassing, alone, is insufficient to explain the present-day abundances of 36Ar and 40Ar in the Martian atmosphere. Similar calculations for 20Ne suggest outgassed volumes of between 100 and 1800 times in excess of that due to volcanism. This results in a distinct Ne/Ar elemental fractionation, with a preference for outgassing argon, of the order of 10 to 17. Although the results must be evaluated within the model uncertainties, the results are compelling in that they unequivocally show the existence of additional sources of atmospheric volatiles and helps define a means to identify them.

  8. Reactivity patterns of transition metal hydrides and alkyls

    Energy Technology Data Exchange (ETDEWEB)

    Jones, W.D. II

    1979-05-01

    The complex PPN/sup +/ CpV(CO)/sub 3/H/sup -/ (Cp=eta/sup 5/-C/sub 5/H/sub 5/ and PPN = (Ph/sub 3/P)/sub 2/) was prepared in 70% yield and its physical properties and chemical reactions investigated. PPN/sup +/ CpV(CO)/sub 3/H/sup -/ reacts with a wide range of organic halides. The organometallic products of these reactions are the vanadium halides PPN/sup +/(CpV(C)/sub 3/X)/sup -/ and in some cases the binuclear bridging hydride PPN/sup +/ (CpV(CO)/sub 3/)/sub 2/H/sup -/. The borohydride salt PPN/sup +/(CpV(CO)/sub 3/BH/sub 4/)/sup -/ has also been prepared. The reaction between CpV(CO)/sub 3/H/sup -/ and organic halides was investigated and compared with halide reductions carried out using tri-n-butyltin hydride. Results demonstrate that in almost all cases, the reduction reaction proceeds via free radical intermediates which are generated in a chain process, and are trapped by hydrogen transfer from CpV(CO)/sub 3/H/sup -/. Sodium amalgam reduction of CpRh(CO)/sub 2/ or a mixture of CpRh(CO)/sub 2/ and CpCo(CO)/sub 2/ affords two new anions, PPN/sup +/ (Cp/sub 2/Rh/sub 3/(CO)/sub 4/)/sup -/ and PPN/sup +/(Cp/sub 2/RhCo(CO)/sub 2/)/sup -/. CpMo(CO)/sub 3/H reacts with CpMo(CO)/sub 3/R (R=CH/sub 3/,C/sub 2/H/sub 5/, CH/sub 2/C/sub 6/H/sub 5/) at 25 to 50/sup 0/C to produce aldehyde RCHO and the dimers (CpMo(CO)/sub 3/)/sub 2/ and (CpMo(CO)/sub 2/)/sub 2/. In general, CpV(CO)/sub 3/H/sup -/ appears to transfer a hydrogen atom to the metal radical anion formed in an electron transfer process, whereas CpMo(CO)/sub 3/H transfers hydride in a 2-electron process to a vacant coordination site. The chemical consequences are that CpV(CO)/sub 3/H/sup -/ generally reacts with metal alkyls to give alkanes via intermediate alkyl hydride species whereas CpMo(CO)/sub 3/H reacts with metal alkyls to produce aldehyde, via an intermediate acyl hydride species.

  9. Reactivity patterns of transition metal hydrides and alkyls

    International Nuclear Information System (INIS)

    The complex PPN+ CpV(CO)3H- (Cp=eta5-C5H5 and PPN = (Ph3P)2) was prepared in 70% yield and its physical properties and chemical reactions investigated. PPN+ CpV(CO)3H- reacts with a wide range of organic halides. The organometallic products of these reactions are the vanadium halides PPN+[CpV(C)3X]- and in some cases the binuclear bridging hydride PPN+ [CpV(CO)3]2H-. The borohydride salt PPN+[CpV(CO)3BH4]- has also been prepared. The reaction between CpV(CO)3H- and organic halides was investigated and compared with halide reductions carried out using tri-n-butyltin hydride. Results demonstrate that in almost all cases, the reduction reaction proceeds via free radical intermediates which are generated in a chain process, and are trapped by hydrogen transfer from CpV(CO)3H-. Sodium amalgam reduction of CpRh(CO)2 or a mixture of CpRh(CO)2 and CpCo(CO)2 affords two new anions, PPN+ [Cp2Rh3(CO)4]- and PPN+[Cp2RhCo(CO)2]-. CpMo(CO)3H reacts with CpMo(CO)3R (R=CH3,C2H5, CH2C6H5) at 25 to 500C to produce aldehyde RCHO and the dimers [CpMo(CO)3]2 and [CpMo(CO)2]2. In general, CpV(CO)3H- appears to transfer a hydrogen atom to the metal radical anion formed in an electron transfer process, whereas CpMo(CO)3H transfers hydride in a 2-electron process to a vacant coordination site. The chemical consequences are that CpV(CO)3H- generally reacts with metal alkyls to give alkanes via intermediate alkyl hydride species whereas CpMo(CO)3H reacts with metal alkyls to produce aldehyde, via an intermediate acyl hydride species

  10. Characterisation of GERDA Phase-I detectors in liquid argon

    International Nuclear Information System (INIS)

    GERDA will search for neutrinoless double beta decay in 76Ge by submerging bare enriched HPGe detectors in liquid argon. In GERDA Phase-I, reprocessed enriched-Ge detectors, which were previously operated by the Heidelberg-Moscow and IGEX collaborations, and reprocessed natural-Ge detectors from Genius-TF, will be redeployed. We have tested the operation and performance of bare HPGe detectors in liquid nitrogen and in liquid argon over more than three years with three non-enriched p-type prototype detectors. The detector handling and mounting procedures have been defined and the Phase-I detector technology, the low-mass assembly and the long-term stability in liquid argon have been tested successfully. The Phase-I detectors were reprocessed by Canberra Semiconductor NV, Olen, according to their standard technology but without the evaporation of a passivation layer. After their reprocessing, the detectors have been mounted in their low-mass holders and their characterisation in liquid argon performed. The leakage current, the counting characteristics and the efficiency of the detectors have been measured. The testing of the detectors was carried out in the liquid argon test stand of the GERDA underground Detector Laboratory (GDL) at LNGS. The detectors are now stored underground under vacuum until their operation in GERDA.

  11. The Spectroscopic Detectability of Argon in the Lunar Atmosphere

    CERN Document Server

    Parker, J W; Gladstone, G R; Shull, J M; Parker, Joel Wm.

    1999-01-01

    Direct measurements of the abundance of argon in the lunar atmosphere were made in 1973 by instruments placed on the Moon during the Apollo 17 mission, but the total daytime abundance is unknown due to instrument saturation effects; thus, until we are able to return to the Moon for improved direct measurements, we must use remote sensing to establish the daytime abundance. In this paper, we present a complete analysis of the potential for measuring argon in the lunar atmosphere via emission-line or absorption-line observations. We come to the surprising conclusion that the lower limit established by the in situ lunar argon measurements implies that any absorption-line measurement of argon in the lower, dayside lunar atmosphere requires analysis in the optically-thick regime. In light of this result, we present the results of our EUVS sounding rocket observations of the lunar occultation of Spica, which provide a new upper limit on the abundance of argon in the daytime lunar atmosphere. We also re-analyze a re...

  12. Determination of fracture strength of δ-zirconium hydrides embedded in zirconium matrix at high temperatures

    Science.gov (United States)

    Kubo, T.; Kobayashi, Y.; Uchikoshi, H.

    2013-04-01

    The fracture strength of δ-zirconium hydrides embedded in a zirconium matrix was determined at temperatures between 25 °C and 250 °C by ring tensile tests using Zircaloy-2 tubes. Essentially all of the present hydrides in the tubes were re-oriented in the radial direction by a temperature cycling treatment and then tensile stress was applied perpendicular to the hydrides to ensure that brittle fracture would occur at the hydrides. The hydrides failed in a brittle manner below 100 °C where-as the zirconium matrix itself underwent ductile fracture without hydride cracking at temperatures above 200 °C under plane stress condition. Brittle fracture of the hydrides continued to occur at temperatures up to 250 °C under plane strain condition, suggesting that the upper limit temperature for hydride fracture, Tupper, was raised by the triaxial stress state under the plane strain condition. The apparent fracture strength of the hydrides, σhydridef, was determined at temperatures below Tupper from the measured fracture strength of the tubes, making a correction for the compressive transformation stress in the hydrides. σhydridef was about 710 MPa at temperatures between 25 °C and 250 °C at both plane stress and plane strain conditions. The temperature dependency was very small in this temperature range. Tupper was almost equivalent to the cross-over temperature between σhydridef and the ultimate tensile strength (UTS), which suggests that, at temperatures above Tupper, the zirconium matrix would undergo ductile fracture before the stress in the hydride is raised above σhydridef, since UTS is smaller than σhydridef.

  13. Metastable argon beam source using a surface wave sustained plasma

    International Nuclear Information System (INIS)

    A new source of metastable argon atoms in the thermal energy range is reported. The source is based on expanding a plasma sustained by electromagnetic surface waves in a quartz tube through a converging nozzle and extracting a beam from the supersonic free-expansion jet. The beam was characterized by time-of-flight measurements which yielded the absolute intensity and velocity distribution of the argon metastables. The source produced a maximum intensity of 6.2x1014 metastables per second per steradian, the highest time-averaged intensity of thermal argon metastables of any source reported to date. A simple picture of an expanding plasma in a recombination regime is used to explain the dependence of the metastable intensity on absorbed power

  14. On the electric breakdown in liquid argon at centimeter scale

    Science.gov (United States)

    Auger, M.; Blatter, A.; Ereditato, A.; Goeldi, D.; Janos, S.; Kreslo, I.; Luethi, M.; von Rohr, C. Rudolf; Strauss, T.; Weber, M. S.

    2016-03-01

    We present a study on the dependence of electric breakdown discharge properties on electrode geometry and the breakdown field in liquid argon near its boiling point. The measurements were performed with a spherical cathode and a planar anode at distances ranging from 0.1 mm to 10.0 mm. A detailed study of the time evolution of the breakdown volt-ampere characteristics was performed for the first time. It revealed a slow streamer development phase in the discharge. The results of a spectroscopic study of the visible light emission of the breakdowns complement the measurements. The light emission from the initial phase of the discharge is attributed to electro-luminescence of liquid argon following a current of drifting electrons. These results contribute to set benchmarks for breakdown-safe design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).

  15. The Simulation of the ATLAS Liquid Argon Calorimetry

    CERN Document Server

    Archambault, J P; Carli, T; Costanzo, D; Dell'Acqua, A; Djama, F; Gallas, M; Fincke-Keeler, M; Khakzad, M; Kiryunin, A; Krieger, P; Leltchouk, M; Loch, P; Ma, H; Menke, S; Monnier, E; Nairz, A; Niess, V; Oakham, G; Oram, C; Pospelov, G; Rajagopalan, S; Rimoldi, A; Rousseau, D; Rutherfoord, J; Seligman, W; Soukharev, A; Strízenec, P; Tóth, J; Tsukerman, I; Tsulaia, V; Unal, G; Grahn, K J

    2008-01-01

    In ATLAS, all of the electromagnetic calorimetry and part of the hadronic calorimetry is performed by a calorimeter system using liquid argon as the active material, together with various types of absorbers. The liquid argon calorimeter consists of four subsystems: the electromagnetic barrel and endcap accordion calorimeters; the hadronic endcap calorimeters, and the forward calorimeters. A very accurate geometrical description of these calorimeters is used as input to the Geant 4-based ATLAS simulation, and a careful modelling of the signal development is applied in the generation of hits. Certain types of Monte Carlo truth information ("Calibration Hits") may, additionally, be recorded for calorimeter cells as well as for dead material. This note is a comprehensive reference describing the simulation of the four liquid argon calorimeteter components.

  16. Energy resolution studies of liquid argon ionization detectors

    International Nuclear Information System (INIS)

    A gridded ionization chamber was used to study the energy resolution in liquid argon with electrons from a 207Bi radioactive source. Argon was purified in the gas phase with a simple and reliable system, capable of reducing the impurity level below 1 ppb O2 equivalent, as inferred by a pulse shape analysis of the ionization signals. The electron spectrum was measured at different drift fields, up to 10.9 KV/cm. At this maximum field, a total energy resolution of 32 keV (fwhm), corresponding to a noise-subtracted energy resolution of 26 keV (fwhm), was obtained for the 976 keV conversion electron line. This value is the best reported so far in liquid argon but is still a factor of seven worse than the theoretical limit set by the Fano factor. The reasons for this discrepancy are discussed. (orig.)

  17. Liquid Argon Calorimetry with LHC-Performance Specifications

    CERN Multimedia

    2002-01-01

    % RD-3 Liquid Argon Calorimetry with LHC-Performance Specifications \\\\ \\\\Good electromagnetic and hadronic calorimetry will play a central role in an LHC detector. Among the techniques used so far, or under development, the liquid argon sampling calorimetry offers high radiation resistence, good energy resolution (electromagnetic and hadronic), excellent calibration stability and response uniformity. Its rate capabilities, however, do not yet match the requirements for LHC. \\\\ \\\\The aim of this proposal is to improve the technique in such a way that high granularity, good hermiticity and adequate rate capabilities are obtained, without compromising the above mentioned properties. To reach this goal, we propose to use a novel structure, the $^{\\prime\\prime}$accordion$^{\\prime\\prime}$, coupled to fast preamplifiers working at liquid argon temperature. Converter and readout electrodes are no longer planar and perpendicular to particles, as usual, but instead they are wiggled around a plane containing particles. ...

  18. A therapeutic experience on Port Wine hemangiomas with Argon Laser

    Directory of Open Access Journals (Sweden)

    Farahvash M

    1997-09-01

    Full Text Available Port wine stains are benign but cosmetically devasting congenital angiomas. The argon laser is a therapeutic device newly applied to this condition. Our program was begun 6 years ago. From the beginning, the study was conceived as a clinical investigation of both the port wine stain and its argon laser therapy. A total of 218 patients with port wine stains have been studied and many aspects of their clinical condition detailed. Employing the Argon laser, test spots have been carried out in patients and the results have been analyzed with clinical aspects of the lesions. Altogether, 501 treatments were performed in 218 patients. Good to excellent results were obtained in 81 patients. Moderate Result was obtained in 31 weak result in 65 patients. Most common complication were hyperpigmentation and depressed scar.

  19. On the Electric Breakdown in Liquid Argon at Centimeter Scale

    CERN Document Server

    Auger, M; Ereditato, A; Goeldi, D; Janos, S; Kreslo, I; Luethi, M; von Rohr, C Rudolf; Strauss, T; Weber, M S

    2015-01-01

    We present a study on the dependence of electric breakdown discharge parameters on electrode geometry and the breakdown field in liquid argon near its boiling point. The measurements were performed with a spherical cathode and a planar anode at distances ranging from 0.1 mm to 10.0 mm. A detailed study of the time evolution of the breakdown volt-ampere characteristics was performed for the first time. It revealed a slow streamer development phase in the discharge. The results of a spectroscopic study of the visible light emission of the breakdowns complement the measurements. The light emission from the initial phase of the discharge is attributed to electro-luminescence of liquid argon following a current of drifting electrons. These results contribute to set benchmarks for breakdown-safe design of ionization detectors, such as Liquid Argon Time Projection Chambers (LAr TPC).

  20. Experiments on hadronic-atom x-ray intensities of hydrides and deuterides

    Energy Technology Data Exchange (ETDEWEB)

    Wiegand, C.E.; Lum, G.K.; Godfrey, G.L.

    1977-04-01

    Kaonic-atom x-ray intensities of elements Z = 3, 6, 8, 11, and 20 were significantly reduced when the elements were in hydride form. The ratios I (ZH/sub m/)/I (Z) have a noticeable Z dependence. Deuterides of C and O showed slightly less x-ray emission than their hydride counterparts.

  1. Study on the Use of Hydride Fuel in High-Performance Light Water Reactor Concept

    Directory of Open Access Journals (Sweden)

    Haileyesus Tsige-Tamirat

    2015-01-01

    Full Text Available Hydride fuels have features which could make their use attractive in future advanced power reactors. The potential benefit of use of hydride fuel in HPLWR without introducing significant modification in the current core design concept of the high-performance light water reactor (HPLWR has been evaluated. Neutronics and thermal hydraulic analyses were performed for a single assembly model of HPLWR with oxide and hydride fuels. The hydride assembly shows higher moderation with softer neutron spectrum and slightly more uniform axial power distribution. It achieves a cycle length of 18 months with sufficient excess reactivity. At Beginning of Cycle the fuel temperature coefficient of the hydride assembly is higher whereas the moderator and void coefficients are lower. The thermal hydraulic results show that the achievable fuel temperature in the hydride assembly is well below the design limits. The potential benefits of the use of hydride fuel in the current design of the HPLWR with the achieved improvements in the core neutronics characteristics are not sufficient to justify the replacement of the oxide fuel. Therefore for a final evaluation of the use of hydride fuels in HPLWR concepts additional studies which include modification of subassembly and core layout designs are required.

  2. Thermal and mechanical properties of zirconium hydrides with various hafnium contents

    International Nuclear Information System (INIS)

    Zirconium (Zr) hydride is currently expected as a neutron shield material for fast reactors. In order to evaluate safety and economic efficiency of the nuclear reactor, the thermal and mechanical properties of the hydride should be understood. In addition, since chemical properties of Zr and hafnium (Hf) are quite similar, Zr contains a few percent Hf generally. Therefore, it is very important to evaluate the effect of Hf content on the properties of Zr hydride. In the present study, fine bulk samples of δ-phase Zr hydrides with various Hf contents were prepared and their thermal and mechanical properties were investigated. We examined the phase states and the microstructure of the hydrides by means of X-ray diffraction and SEM/EDX analyses. In the temperature range from room temperature to 673 K, the heat capacity and the thermal diffusivity of the hydrides were measured and the thermal conductivity was evaluated. The Vickers hardness and the sound velocity of the hydrides were measured at room temperature, and the elastic modulus was calculated from the measured sound velocity. The effects of temperature and Hf content on the properties of Zr hydrides were studied. (author)

  3. Hydride precipitation and its influence on mechanical properties of notched and unnotched Zircaloy-4 plates

    International Nuclear Information System (INIS)

    The hydride formation and its influence on the mechanical performance of hydrided Zircaloy-4 plates containing different hydrogen contents were studied at room temperature. For the unnotched plate samples with the hydrogen contents ranging from 25 to 850 wt. ppm, the hydrides exerted an insignificant effect on the tensile strength, while the ductility was severely degraded with increasing hydrogen content. The fracture mode and degree of embrittlement were strongly related to the hydrogen content. When the hydrogen content reached a level of 850 wt. ppm, the plate exhibited negligible ductility, resulting in almost completely brittle behavior. For the hydrided notched plate, the tensile stress concentration associated with the notch tip facilitated the hydride accumulation at the region near the notch tip and the premature crack propagation through the hydride fracture during hydriding. The final brittle through-thickness failure for this notched sample was mainly attributed to the formation of a continuous hydride network on the thickness section and the obtained very high hydrogen concentration (estimated to be 1965 wt. ppm)

  4. Vaporization kinetics of Sb2S3 in argon fluid

    Institute of Scientific and Technical Information of China (English)

    杨勇; 华一新

    2003-01-01

    The vaporization kinetics of antimony trisulfide in argon fluid was studied with thermogravimetry at 873- 1 173 K. A theoretical model was developed to calculate the overall rate constant and the mass transfer coefficient ingas phase. The experimental results show that the vaporization rate is enhanced with increasing temperature and ar-gon flow-rate. The evaporation rate is mainly controlled by mass transport in the gas phase. The apparent activationenergy for the process is found to be 55.54 kJ/mol. It is demonstrated that the mass transfer coefficient in gas phaseis decreased with increasing temperature.

  5. Modelling of a supersonic ICP argon-hydrogen expansion

    International Nuclear Information System (INIS)

    An expanding argon-hydrogen plasma is investigated by means of simulations. The model is a hydrodynamical model specific for plasma expansions, taking into account the conservation laws of mass, momentum and energy. The code includes the Rankine-Hugoniot relations to calculate shock jump conditions. Results are shown for the expansion from an inductively coupled plasma (ICP) with a separated Laval nozzle. The expansion discussed here is a 'weakly' under-expanding argon-hydrogen plasma. The results from the ICP expansion are verified with probe measurements

  6. Attosecond-correlated dynamics of two electrons in argon

    Indian Academy of Sciences (India)

    V Sharma; N Camus; B Fischer; M Kremer; A Rudenko; B Bergues; M Kuebel; N G Johnson; M F Kling; T Pfeifer; J Ullrich; R Moshammer

    2014-01-01

    In this work we explored strong field-induced decay of doubly excited transient Coulomb complex Ar** → Ar2++2. We measured the correlated two-electron emission as a function of carrier envelop phase (CEP) of 6 fs pulses in the non-sequential double ionization (NSDI) of argon. Classical model calculations suggest that the intermediate doubly excited Coulomb complex loses memory of its formation dynamics. We estimated the ionization time difference between the two electrons from NSDI of argon and it is 200 ± 100 as (N Camus et al, Phys. Rev. Lett. 108, 073003 (2012)).

  7. Mathematical modeling of the nickel/metal hydride battery system

    Energy Technology Data Exchange (ETDEWEB)

    Paxton, B K [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering

    1995-09-01

    A group of compounds referred to as metal hydrides, when used as electrode materials, is a less toxic alternative to the cadmium hydroxide electrode found in nickel/cadmium secondary battery systems. For this and other reasons, the nickel/metal hydride battery system is becoming a popular rechargeable battery for electric vehicle and consumer electronics applications. A model of this battery system is presented. Specifically the metal hydride material, LaNi{sub 5}H{sub 6}, is chosen for investigation due to the wealth of information available in the literature on this compound. The model results are compared to experiments found in the literature. Fundamental analyses as well as engineering optimizations are performed from the results of the battery model. In order to examine diffusion limitations in the nickel oxide electrode, a ``pseudo 2-D model`` is developed. This model allows for the theoretical examination of the effects of a diffusion coefficient that is a function of the state of charge of the active material. It is found using present data from the literature that diffusion in the solid phase is usually not an important limitation in the nickel oxide electrode. This finding is contrary to the conclusions reached by other authors. Although diffusion in the nickel oxide active material is treated rigorously with the pseudo 2-D model, a general methodology is presented for determining the best constant diffusion coefficient to use in a standard one-dimensional battery model. The diffusion coefficients determined by this method are shown to be able to partially capture the behavior that results from a diffusion coefficient that varies with the state of charge of the active material.

  8. Uranium-zirconium hydride TRIGA-LEU fuel

    International Nuclear Information System (INIS)

    The development and testing of TRIGA-LEU fuel with up to 45 wt-% U is described. Topics that are discussed include properties of hydride fuels, the prompt negative temperature coefficient, pulse heating tests, fission product retention, and the limiting design basis parameter and values. General specifications for Er-U-ZrH TRIGA-LEU fuel with 8.5 to 45 wt-% U and an outline of the inspections during manufacture of the fuel are also included. (author). 8 figs, 1 tab

  9. Hydride Ions, HCO+ and Ionizing Irradiation in Star Forming Region

    Science.gov (United States)

    Benz, Arnold O.; Bruderer, Simon; van Dishoeck, Ewine

    2016-06-01

    Hydrides are fundamental precursor molecules in cosmic chemistry and many hydride ions have become observable in high quality for the first time thanks to the Herschel Space Observatory. Ionized hydrides, such as CH+ and OH+ and also HCO+ affect the chemistry of molecules such as water. They also provide complementary information on irradiation by far UV (FUV) or X-rays and gas temperature.We explore hydrides of the most abundant heavier elements in an observational survey covering star forming regions with different mass and evolutionary state. Twelve YSOs were observed with HIFI on Herschel in 6 spectral settings providing fully velocity-resolved line profiles. The YSOs include objects of low (Class 0 and I), intermediate, and high mass, with luminosities ranging from 4 Ls to 2 105 Ls.The targeted lines of CH+, OH+, H2O+, and C+ are detected mostly in blue-shifted absorption. H3O+ and SH+ are detected in emission and only toward some high-mass objects. For the low-mass YSOs the column density ratios of CH+/OH+ can be reproduced by simple chemical models implying an FUV flux of 2 – 400 times the ISRF at the location of the molecules. In two high-mass objects, the UV flux is 20 – 200 times the ISRF derived from absorption lines, and 300 – 600 ISRF using emission lines. Upper limits for the X-ray luminosity can be derived from H3O+ observations for some low-mass objects.If the FUV flux required for low-mass objects originates at the central protostar, a substantial FUV luminosity, up to 1.5 Ls, is required. For high-mass regions, the FUV flux required to produce the observed molecular ratios is smaller than the unattenuated flux expected from the central object(s) at the Herschel beam radius. This is consistent with an FUV flux reduced by circumstellar extinction or by bloating of the protostar.The ion molecules are proposed to form in FUV irradiated cavity walls that are shocked by the disk wind. The shock region is turbulent, broadening the lines to some 1

  10. Research in Nickel/Metal Hydride Batteries 2016

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-10-01

    Full Text Available Nineteen papers focusing on recent research investigations in the field of nickel/metal hydride (Ni/MH batteries have been selected for this Special Issue of Batteries. These papers summarize the joint efforts in Ni/MH battery research from BASF, Wayne State University, the National Institute of Standards and Technology, Michigan State University, and FDK during 2015–2016 through reviews of basic operational concepts, previous academic publications, issued US Patent and filed Japan Patent Applications, descriptions of current research results in advanced components and cell constructions, and projections of future works.

  11. The calculated rovibronic spectrum of scandium hydride, ScH

    CERN Document Server

    Lodi, Lorenzo; Tennyson\\, Jonathan

    2015-01-01

    The electronic structure of six low-lying electronic states of scandium hydride, $X\\,{}^{1}\\Sigma^+$, $a\\,{}^{3}\\Delta$, $b\\,{}^{3}\\Pi$, $A\\,{}^{1}\\Delta$ $c\\,{}^{3}\\Sigma^+$, and $B\\,{}^{1}\\Pi$, is studied using multi-reference configuration interaction as a function of bond length. Diagonal and off-diagonal dipole moment, spin-orbit coupling and electronic angular momentum curves are also computed. The results are benchmarked against experimental measurements and calculations on atomic scandium. The resulting curves are used to compute a line list of molecular ro-vibronic transitions for $^{45}$ScH.

  12. Alkyl and Hydride-Olefin Complexes of Niobocene

    NARCIS (Netherlands)

    Klazinga, A.H.; Teuben, J.H.

    1980-01-01

    Reactions of Cp2NbCl2 with RMgCl (R = n-C3H7, i-C3H7, n-C4H9, s-C4H9 and n-C5H11) give niobocene hydride olefin complexes Cp2Nb(H)L (L = C3H6, C4H8 and C5H10). The last step of the reaction probably proceeds via a stereospecific β-H elimination from the monoalkyl species Cp2NbR. Decomposition of n-a

  13. Electrochemical process and production of novel complex hydrides

    Science.gov (United States)

    Zidan, Ragaiy

    2013-06-25

    A process of using an electrochemical cell to generate aluminum hydride (AlH.sub.3) is provided. The electrolytic cell uses a polar solvent to solubilize NaAlH.sub.4. The resulting electrochemical process results in the formation of AlH.sub.3. The AlH.sub.3 can be recovered and used as a source of hydrogen for the automotive industry. The resulting spent aluminum can be regenerated into NaAlH.sub.4 as part of a closed loop process of AlH.sub.3 generation.

  14. Equilibrium composition for the reaction of plutonium hydride with air

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    There are six independent constituents with 4 chemical elements, i.e. PuH2.7(s), PuN(s), Pu2O3(s), N2, O2 and H2, therefore , the system described involves of 2 independent reactions ,both those of the experimental, which indicates that the chemical equilibrium is nearly completely approached. Therefore, it is believed that the reaction rate of plutonium hydride with air is extremely rapid. The present paper has briefly discussed the simultaneous reactions and its thermodynamic coupling effect.

  15. Comparison between different reactions of group IV hydride with H

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Shaolong; ZHANG; Xuqiang; ZHANG; Qinggang; ZHANG; Yici

    2006-01-01

    The four-dimensional time-dependent quantum dynamics calculations for reactions of group IV hydride with H are carried out by employing the semirigid vibrating rotor target model and the time-dependent wave packet method. The reaction possibility, cross section and rate constants for reactions (H+SiH4 and H+GeH4) in different initial vibrational and rotational states are obtained. The common feature for such kind of reaction process is summarized. The theoretical result is consistent with available measurement, which indicates the credibility of this theory and the potential energy surface.

  16. Another Look at the Mechanisms of Hydride Transfer Enzymes with Quantum and Classical Transition Path Sampling.

    Science.gov (United States)

    Dzierlenga, Michael W; Antoniou, Dimitri; Schwartz, Steven D

    2015-04-01

    The mechanisms involved in enzymatic hydride transfer have been studied for years, but questions remain due, in part, to the difficulty of probing the effects of protein motion and hydrogen tunneling. In this study, we use transition path sampling (TPS) with normal mode centroid molecular dynamics (CMD) to calculate the barrier to hydride transfer in yeast alcohol dehydrogenase (YADH) and human heart lactate dehydrogenase (LDH). Calculation of the work applied to the hydride allowed for observation of the change in barrier height upon inclusion of quantum dynamics. Similar calculations were performed using deuterium as the transferring particle in order to approximate kinetic isotope effects (KIEs). The change in barrier height in YADH is indicative of a zero-point energy (ZPE) contribution and is evidence that catalysis occurs via a protein compression that mediates a near-barrierless hydride transfer. Calculation of the KIE using the difference in barrier height between the hydride and deuteride agreed well with experimental results.

  17. Hydrogenation reaction characteristics and properties of its hydrides for magnetic regenerative material HoCu2

    Institute of Scientific and Technical Information of China (English)

    金滔; 吴梦茜; 黄迦乐; 汤珂; 陈立新

    2016-01-01

    The hydrogenation reaction characteristics and the properties of its hydrides for the magnetic regenerative material HoCu2 (CeCu2-type) of a cryocooler were investigated. The XRD testing reveals that the hydrides of HoCu2 were a mixture of Cu, unknown hydride I, and unknown hydride II. Based on the PCT (pressure−concentration−temperature) curves under different reaction temperatures, the relationships among reaction temperature, equilibrium pressure, and maximum hydrogen absorption capacity were analyzed and discussed. The enthalpy changeΔH and entropy changeΔS as a result of the whole hydrogenation process were also calculated from the PCT curves. The magnetization and volumetric specific heat capacity of the hydride were also measured by SQUID magnetometer and PPMS, respectively.

  18. Mobility and chemical bond of hydrogen in titanium and palladium hydrides

    International Nuclear Information System (INIS)

    The probabilities for π- meson capture by hydrogen are measured at 25, 155 and 200 deg C in TiHsub(1.65) hydride and at 25, -120 and -196 deg C in PdHsub(0.67) hydride. An analysis of the results obtained shows that within the accuracy of the measurements (approximately 10%) a sharp (up to 1012) change in the mobility of hydrogen in the hydrides induced by temperature changes within the ranges indicated does not noticeably affect the probabilities for π- meson capture by bound hydrogen, i.e. does not lead to appreciable changes in the Me-H bond. A comparison of the capture probabilities for palladium hydride and hydrides of neighboring transition metals shows that there are no pronounced anomalies in the Pd-H bond

  19. Formation of alloys in Ti-V system in hydride cycle and synthesis of their hydrides in self-propagating high-temperature synthesis regime

    Energy Technology Data Exchange (ETDEWEB)

    Aleksanyan, A.G., E-mail: a.g.aleks_yan@mail.ru [A.B. Nalbandyan Institute of Chemical Physics of Armenian NAS, 5/2 P.Sevak Str., Yerevan 0014 (Armenia); Dolukhanyan, S.K. [A.B. Nalbandyan Institute of Chemical Physics of Armenian NAS, 5/2 P.Sevak Str., Yerevan 0014 (Armenia); Shekhtman, V.Sh. [Institute of Solid State Physics, RAS, Chernogolovka, Moscow District 142432 (Russian Federation); Huot, J., E-mail: jacques_huot@uqtr.ca [Institut de recherche sur l' hydrogene, Universite du Quebec a Trois-Rivieres (Canada); Ter-Galstyan, O.P.; Mnatsakanyan, N.L. [A.B. Nalbandyan Institute of Chemical Physics of Armenian NAS, 5/2 P.Sevak Str., Yerevan 0014 (Armenia)

    2011-09-15

    Research highlights: > We synthesize Ti-V alloys by new 'hydride cycle' method. Structural characteristics of formed alloys we investigate by X-ray diffraction. > We show that the alloys contain mainly BCC crystal structure. > We investigate the interaction of the synthesized alloys with hydrogen in combustion regime. > We study the properties of hydrides by X-ray, DTA and DSC analyses. - Abstract: In the present work, the possibility of formation of titanium and vanadium based alloys of BCC structure using hydride cycle was investigated. The mechanism of formation of alloys in Ti-V system from the powders of hydrides TiH{sub 2} and VH{sub 0.9} (or of V) by compaction followed by dehydrogenation was studied. Then, the interaction of the synthesized alloys with hydrogen in combustion regime (self-propagating high-temperature synthesis, SHS) resulting in hydrides of these alloys was investigated. DTA and DSC analyses of some alloys and their hydrides were performed and their thermal characteristics were measured.

  20. Uranium-liquid argon calorimetry: preliminary results from the DO tests

    International Nuclear Information System (INIS)

    The motivations for using uranium and liquid argon in sampling calorimetry are reviewed and the pros and cons of the technique are discussed. Preliminary results of the DO uranium-liquid argon test program are presented. 9 refs., 7 figs

  1. Optical emission spectroscopy of argon and hydrogen-containing plasmas

    Science.gov (United States)

    Siepa, Sarah; Danko, Stephan; Tsankov, Tsanko V.; Mussenbrock, Thomas; Czarnetzki, Uwe

    2015-09-01

    Optical emission spectroscopy (OES) on neutral argon is applied to investigate argon, hydrogen and hydrogen-silane plasmas. The spectra are analyzed using an extensive collisional-radiative model (CRM), from which the electron density and the electron temperature (or mean energy) can be calculated. The CRM also yields insight into the importance of different excited species and kinetic processes. The OES measurements are performed on pure argon plasmas at intermediate pressure. Besides, hydrogen and hydrogen-silane plasmas are investigated using argon as a trace gas. Especially for the gas mixture discharges, CRMs for low and high pressure differ substantially. The commonly used line-ratio technique is found to lose its sensitivity for gas mixture discharges at higher pressure. A solution using absolutely calibrated line intensities is proposed. The effect of radiation trapping and the shape of the electron energy distribution function on the results are discussed in detail, as they have been found to significantly influence the results. This work was supported by the Ruhr University Research School PLUS, funded by Germany's Excellence Initiative [DFG GSC 98/3].

  2. Measurement of the argon plasma temperature by use of pyrometer

    International Nuclear Information System (INIS)

    The author describes in detail how to use pyrometer to measure the plasma temperature. The temperatures of shock-generated argon plasmas are given in the present work. Measured results of temperature-pressure curve are compared with calculated results using Saha-Debye-Huckel model, which are in good agreement

  3. Turbulence and transport in a magnetized argon plasma

    International Nuclear Information System (INIS)

    An experimental study on turbulence and transport in the highly ionized argon plasma of a hollow cathode discharge is described. In order to determine the plasma parameters three standard diagnostics have been used, whilst two diagnostics have been developed to study the plasma turbulence. (Auth.)

  4. Thermophysical properties of multi-shock compressed dense argon.

    Science.gov (United States)

    Chen, Q F; Zheng, J; Gu, Y J; Chen, Y L; Cai, L C; Shen, Z J

    2014-02-21

    In contrast to the single shock compression state that can be obtained directly via experimental measurements, the multi-shock compression states, however, have to be calculated with the aid of theoretical models. In order to determine experimentally the multiple shock states, a diagnostic approach with the Doppler pins system (DPS) and the pyrometer was used to probe multiple shocks in dense argon plasmas. Plasma was generated by a shock reverberation technique. The shock was produced using the flyer plate impact accelerated up to ∼6.1 km/s by a two-stage light gas gun and introduced into the plenum argon gas sample, which was pre-compressed from the environmental pressure to about 20 MPa. The time-resolved optical radiation histories were determined using a multi-wavelength channel optical transience radiance pyrometer. Simultaneously, the particle velocity profiles of the LiF window was measured with multi-DPS. The states of multi-shock compression argon plasma were determined from the measured shock velocities combining the particle velocity profiles. We performed the experiments on dense argon plasmas to determine the principal Hugonoit up to 21 GPa, the re-shock pressure up to 73 GPa, and the maximum measure pressure of the fourth shock up to 158 GPa. The results are used to validate the existing self-consistent variational theory model in the partial ionization region and create new theoretical models. PMID:24559345

  5. Thermal decomposition of Yttrium(III) isovalerate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao;

    2016-01-01

    The thermal behaviour of yttrium(III) isovalerate (Y(C4H9CO2)3) was studied in argon by means of thermogravimetry, differential thermal analysis, FTIR-spectroscopy, hot-stage optical microscopy and X-ray diffraction with a laboratory Cu-tube source as well as with a synchrotron radiation source...

  6. Thermal decomposition of yttrium(III) valerate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Tang, Xiao;

    2014-01-01

    The thermal decomposition of yttrium(III) valerate (Y(C4H9CO2)3) was studied in argon by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction, in-situ synchrotron diffraction and hot-stage microscopy as well as room temperature optical microscopy. Melting...

  7. Thermal decomposition of yttrium(III) hexanoate in argon

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Suarez Guevara, Maria Josefina; Attique, Fahmida;

    2015-01-01

    The thermal decomposition of yttrium(III) hexanoate (Y(C5H11CO2)3)·xH2O in argon was studied by means of thermogravimetry, differential thermal analysis, IR-spectroscopy, X-ray diffraction at a laboratory Cu-tube source and in-situ experiments at a synchrotron radiation source as well as hot...

  8. A 2-Dimensional Fluid Model for an Argon Rf Discharge

    NARCIS (Netherlands)

    Passchier, J. D. P.; W. J. Goedheer,

    1993-01-01

    A fluid model for an argon rf discharge in a cylindrical discharge chamber is presented. The model contains the particle balances for electrons and ions and the electron energy balance. A nonzero autobias voltage is obtained by imposing the condition that the time-averaged current toward the powered

  9. Study of Liquid Argon Dopants for LHC Hadron Calorimetry

    CERN Multimedia

    2002-01-01

    Hadron calorimetry based on the Liquid Argon Ionisation Chamber technique is one of the choice techniques for LHC-experimentation. A systematic study of the effect of selected dopants on Liquid Argon (LAr) will be carried out with the aim to achieve an improvement on: \\item (i)~``Fast Liquid Argon'' search and study of dopants to increase the drift velocity. It has been already shown that CH&sub4. added at a fraction of one percent increases the drift velocity by a factor of two or more. \\item (ii)~``Compensated Liquid Argon'' search and study of dopants to increase the response to densely ionising particles, resulting in improved compensation, such as photosensitive dopants. \\end{enumerate}\\\\ \\\\ Monitoring of the parameters involved in understanding the response of a calorimeter is essential. In case of doped LAr, the charge yield, the non-saturated drift velocity and the electron lifetime in the liquid should be precisely and simultaneously monitored as they all vary with the level of dopant concentrati...

  10. LArGe. A liquid argon scintillation veto for GERDA

    International Nuclear Information System (INIS)

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in 76Ge, by operating naked germanium detectors submersed into 65 m3 of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m3 (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 103 have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10-2 cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural 42Ar abundance (in parallel to Gerda), and have indication for the 2νββ-decay in natural germanium. (orig.)

  11. LArGe. A liquid argon scintillation veto for GERDA

    Energy Technology Data Exchange (ETDEWEB)

    Heisel, Mark

    2011-04-13

    LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in {sup 76}Ge, by operating naked germanium detectors submersed into 65 m{sup 3} of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m{sup 3} (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10{sup 3} have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10{sup -2} cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural {sup 42}Ar abundance (in parallel to Gerda), and have indication for the 2{nu}{beta}{beta}-decay in natural germanium. (orig.)

  12. Design of capsules capable of argon-filling

    International Nuclear Information System (INIS)

    The possibility of the use of polycarbosilane capsules as fuel container in inertial confinement fusion experiments was analyzed in the paper. Primary study indicates that the polycarbosilane capsules can be filled with argon by means of diffusion and possess reasonable retention time for deuterium. (author)

  13. Separation of covalent hydrides by gas-solid chromatography

    International Nuclear Information System (INIS)

    A fully automated method was developed for separating the hydrides of elements of the IVth to VIIIth main subgroup of the periodic system and of Kr and Xe on the basis of their volatility using gas chromatography. The automated instrument allowing to carry out reduction, separation of the gaseous phase, the loading of a PORAPAK-packed column, the chromatographic separation and sampling was controlled by a HP 2116B computer. The elution time, peak area and the number of theoretical column plates were computed from chromatograms. The capture probably proceeded by a type of nonpolar nonspecific sorption (ΔH/Tsub(b) = 19.2 cal/mol.deg). The height of the theoretical plate was 0.05 to 0.1 cm. The technique may be used as a routine radiochemical method for group separations and for the separation of radioactive hydrides contained in the solution of targets irradiated with neutrons or charged particles in the preparation of radioactive sources of short-lived radionuclides, or in destructive activation analysis. (M.K.)

  14. Reactions of ruthenium hydrides with ethyl-vinyl sulfide.

    Science.gov (United States)

    Dahcheh, Fatme; Stephan, Douglas W

    2014-03-01

    The Ru-hydride precursors (Im(OMe)2)(PPh3)2RuHCl () and (Me2Im(OMe)2)(PPh3)2RuHCl () reacted with ethyl-vinyl-sulfide to give ((MeOCH2CH2)C3H2N2(CH2CH(OMe))RuCl(PPh3)2 () and ((MeOCH2CH2)C3Me2N2(CH2CH(OMe))RuCl(PPh3)2 (), respectively. Dissolution of () in C6D6 prompts formation of ((MeOCH2CH2)C5H6N2(CHCH)RuCl(PPh3)2 (). The analogous reactions of the bis-carbene Ru-hydride precursors (Im(OMe)2)(IMes)(PPh3)RuHCl (), (Im(OMe)2)(SIMes)(PPh3)RuHCl () and (Im(OMe)2)(IMes-Cl2)(PPh3)RuHCl () gave ((MeOCH2CH2)C3H2N2(CHCH)RuCl(PPh3)(NHC) (NHC = IMes (), SIMes (), IMes-Cl2 (), respectively. The formation of compounds () and () is thought to go through an initial insertion of the vinyl-fragment into the Ru-H prompting subsequent C-H activation and loss of diethyl sulfide. This yields () and (), while subsequent loss of methanol yields () and (-). PMID:24441082

  15. Electronic structure of the palladium hydride studied by compton scattering

    CERN Document Server

    Mizusaki, S; Yamaguchi, M; Hiraoka, N; Itou, M; Sakurai, Y

    2003-01-01

    The hydrogen-induced changes in the electronic structure of Pd have been investigated by Compton scattering experiments associated with theoretical calculations. Compton profiles (CPs) of single crystal of Pd and beta phase hydride PdH sub x (x=0.62-0.74) have been measured along the [100], [110] and [111] directions with a momentum resolution of 0.14-0.17 atomic units using 115 keV x-rays. The theoretical Compton profiles have been calculated from the wavefunctions obtained utilizing the full potential linearized augmented plane wave method within the local density approximation for Pd and stoichiometric PdH. The experimental and the theoretical results agreed well with respect to the difference in the CPs between PdH sub x and Pd, and the anisotropy in the CPs of Pd or PdH sub x. This study provides lines of evidence that upon hydride formation the lowest valance band of Pd is largely modified due to hybridization with H 1s-orbitals and the Fermi energy is raised into the sp-band. (author)

  16. Gallium Nitride Nanowires Grown by Hydride Vapor Phase Epitaxy

    Institute of Scientific and Technical Information of China (English)

    LIU Zhan-Hui; XIU Xiang-Qan; YAN Huai-Yue; ZHANG Rong; XIE Zi-Li; HAN Ping; SHI Yi; ZHENG You-Dou

    2011-01-01

    @@ GaN nanowires are grown by hydride vapor phase epitaxy using nickel as a catalyst.The properties of the obtained GaN nanowires are characterized by scanning and transmission electron microscopy,electron diffraction,roomtemperature photoluminescence and energy dispersive spectroscopy.The results show that the nanowires are wurtzite single crystals growing along the[0001]direction and a redshift in the photoluminescence is observed due to a superposition of several effects.The Raman spectra are close to those of the bulk GaN and the significantly broadening of those modes indicates the phonon confinement effects associated with the nanoscale dimensions of the system.%GaN nanowires are grown by hydride vapor phase epitaxy using nickel as a catalyst. The properties of the obtained GaN nanowires are characterized by scanning and transmission electron microscopy, electron diffraction, room-temperature photoluminescence and energy dispersive spectroscopy. The results show that the nanowires are wurtzite single crystals growing along the [0001] direction and a redshift in the photoluminescence is observed due to a superposition of several effects. The Raman spectra are close to those of the bulk GaN and the significantly broadening of those modes indicates the phonon confinement effects associated with the nanoscale dimensions of the system.

  17. Thermodynamic Calculation on the Formation of Titanium Hydride

    Institute of Scientific and Technical Information of China (English)

    Jing-wei Zhao; Hua Ding; Xue-feng Tian; Wen-juan Zhao; Hong-liang Hou

    2008-01-01

    A modified Miedema model, using interrelationship among the basic properties of elements Ti and H, is employed to calculate the standard enthalpy of formation of titanium hydride TiHx (1≤x≤2). Based on Debye theories of solid thermal capacity, the vibrational entropy, as well as electronic entropy, is acquired by quantum mechanics and statistic thermodynamics methods, and a new approach is presented to calculate the standard entropy of formation of Till2. The values of standard enthalpy of formation of TiHx decrease linearly with increase of x. The calculated results of standard enthalpy, entropy, and free energy of forma- tion of Till2 at 298.16 K are -142.39 kJ/mol, -143.0 J/(mol-K) and -99.75 k J/tool, respectively, which is consistent with the previously-reported data obtained by either experimental or theoretical calculation methods. The results show that the thermodynamic model for titanium hydride is reasonable.

  18. Measurement of nuclear fuel pin hydriding utilizing epithermal neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Miller, W.H. [Univ. of Missouri, Columbia, MO (United States); Farkas, D.M.; Lutz, D.R. [General Electric Co., Pleasanton, CA (United States)

    1996-12-31

    The measurement of hydrogen or zirconium hydriding in fuel cladding has long been of interest to the nuclear power industry. The detection of this hydrogen currently requires either destructive analysis (with sensitivities down to 1 {mu}g/g) or nondestructive thermal neutron radiography (with sensitivities on the order of a few weight percent). The detection of hydrogen in metals can also be determined by measuring the slowing down of neutrons as they collide and rapidly lose energy via scattering with hydrogen. This phenomenon is the basis for the {open_quotes}notched neutron spectrum{close_quotes} technique, also referred to as the Hysen method. This technique has been improved with the {open_quotes}modified{close_quotes} notched neutron spectrum technique that has demonstrated detection of hydrogen below 1 {mu}g/g in steel. The technique is nondestructive and can be used on radioactive materials. It is proposed that this technique be applied to the measurement of hydriding in zirconium fuel pins. This paper summarizes a method for such measurements.

  19. Method of generating hydrogen-storing hydride complexes

    Science.gov (United States)

    Srinivasan, Sesha S; Niemann, Michael U; Goswami, D. Yogi; Stefanakos, Elias K

    2013-05-14

    A ternary hydrogen storage system having a constant stoichiometric molar ratio of LiNH.sub.2:MgH.sub.2:LiBH.sub.4 of 2:1:1. It was found that the incorporation of MgH.sub.2 particles of approximately 10 nm to 20 nm exhibit a lower initial hydrogen release temperature of 150.degree. C. Furthermore, it is observed that the particle size of LiBNH quaternary hydride has a significant effect on the hydrogen sorption concentration with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160.degree. C. and the other around 300.degree. C., with the main hydrogen release temperature reduced from 310.degree. C. to 270.degree. C., while hydrogen is first reversibly released at temperatures as low as 150.degree. C. with a total hydrogen capacity of 6 wt. % to 8 wt. %. Detailed thermal, capacity, structural and microstructural properties have been demonstrated and correlated with the activation energies of these materials.

  20. Superconductive "sodalite"-like clathrate calcium hydride at high pressures

    CERN Document Server

    Wang, Hui; Tanaka, Kaori; Iitaka, Toshiaki; Ma, Yanming

    2012-01-01

    Hydrogen-rich compounds hold promise as high-temperature superconductors under high pressures. Recent theoretical hydride structures on achieving high-pressure superconductivity are composed mainly of H2 fragments. Through a systematic investigation of Ca hydrides with different hydrogen contents using particle-swam optimization structural search, we show that in the stoichiometry CaH6 a body-centred cubic structure with hydrogen that forms unusual "sodalite" cages containing enclathrated Ca stabilizes above pressure 150 GPa. The stability of this structure is derived from the acceptance by two H2 of electrons donated by Ca forming a "H4" unit as the building block in the construction of the 3-dimensional sodalite cage. This unique structure has a partial occupation of the degenerated orbitals at the zone centre. The resultant dynamic Jahn-Teller effect helps to enhance electron-phonon coupling and leads to superconductivity of CaH6. A superconducting critical temperature (Tc) of 220-235 K at 150 GPa obtained...

  1. A quantitative phase field model for hydride precipitation in zirconium alloys: Part I. Development of quantitative free energy functional

    International Nuclear Information System (INIS)

    A temperature dependent, quantitative free energy functional was developed for the modeling of hydride precipitation in zirconium alloys within a phase field scheme. The model takes into account crystallographic variants of hydrides, interfacial energy between hydride and matrix, interfacial energy between hydrides, elastoplastic hydride precipitation and interaction with externally applied stress. The model is fully quantitative in real time and real length scale, and simulation results were compared with limited experimental data available in the literature with a reasonable agreement. The work calls for experimental and/or theoretical investigations of some of the key material properties that are not yet available in the literature

  2. Conversion of an atomic to a molecular argon ion and low pressure argon relaxation

    Science.gov (United States)

    M, N. Stankov; A, P. Jovanović; V, Lj Marković; S, N. Stamenković

    2016-01-01

    The dominant process in relaxation of DC glow discharge between two plane parallel electrodes in argon at pressure 200 Pa is analyzed by measuring the breakdown time delay and by analytical and numerical models. By using the approximate analytical model it is found that the relaxation in a range from 20 to 60 ms in afterglow is dominated by ions, produced by atomic-to-molecular conversion of Ar+ ions in the first several milliseconds after the cessation of the discharge. This conversion is confirmed by the presence of double-Gaussian distribution for the formative time delay, as well as conversion maxima in a set of memory curves measured in different conditions. Finally, the numerical one-dimensional (1D) model for determining the number densities of dominant particles in stationary DC glow discharge and two-dimensional (2D) model for the relaxation are used to confirm the previous assumptions and to determine the corresponding collision and transport coefficients of dominant species and processes. Project supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Grant No. ON171025).

  3. Observations of acoustic-wave-induced superluminescence in an argon plasma

    International Nuclear Information System (INIS)

    It is shown that in an argon discharge plasma it is possible to obtain overpopulation of certain electronic levels of atomic argon under the influence of acoustic waves. When the specified threshold is exceeded, then a superluminescence (in the form of light flashes) from the overpopulated electronic levels of atomic argon is observed

  4. 21 CFR 874.4490 - Argon laser for otology, rhinology, and laryngology.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Argon laser for otology, rhinology, and laryngology. 874.4490 Section 874.4490 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... Argon laser for otology, rhinology, and laryngology. (a) Identification. The argon laser device for...

  5. Argon metastable dynamics and lifetimes in a direct current microdischarge

    Science.gov (United States)

    Stefanović, Ilija; Kuschel, Thomas; Schröter, Sandra; Böke, Marc

    2014-09-01

    In this paper we study the properties of a pulsed dc microdischarge with the continuous flow of argon. Argon metastable lifetimes are measured by tunable diode laser absorption spectroscopy (TDLAS) and are compared with calculated values which yield information about excitation and de-excitation processes. By increasing the gas flow-rate about 5 times from 10 to 50 sccm, the Arm lifetime increases from 1 to 5 μs due to the reduction of metastable quenching with gas impurities. Optical emission spectroscopy reveals nitrogen and water molecules as the main gas impurities. The estimated N2 density [N2] = 0.1% is too low to explain the measured metastable lifetimes. Water impurity was found to be the main de-excitation source of argon metastable atoms due to high quenching coefficients. The water impurity level of [H2O] = 0.15% to 1% is sufficient to bring calculated metastable lifetimes in line with experiments. The maximum value of water content in the discharge compared to the argon atoms is estimated to approximately 6%, due to the large surface to volume ratio of the microdischarge. The current pulse releases the water molecules from the electrode surface and they are either re-adsorbed in the time between 0.4 ms for [H2O] = 1% and 2.6 ms for [H2O] = 0.15% or pumped out of the discharge with the speed equal to the gas flow-rate. Depending on its partial pressure, the water impurity re-adsorption time is of the order of magnitude or less then the argon gas residence time.

  6. Main Group Lewis Acid-Mediated Transformations of Transition-Metal Hydride Complexes.

    Science.gov (United States)

    Maity, Ayan; Teets, Thomas S

    2016-08-10

    This Review highlights stoichiometric reactions and elementary steps of catalytic reactions involving cooperative participation of transition-metal hydrides and main group Lewis acids. Included are reactions where the transition-metal hydride acts as a reactant as well as transformations that form the metal hydride as a product. This Review is divided by reaction type, illustrating the diverse roles that Lewis acids can play in mediating transformations involving transition-metal hydrides as either reactants or products. We begin with a discussion of reactions where metal hydrides form direct adducts with Lewis acids, elaborating the structure and dynamics of the products of these reactions. The bulk of this Review focuses on reactions where the transition metal and Lewis acid act in cooperation, and includes sections on carbonyl reduction, H2 activation, and hydride elimination reactions, all of which can be promoted by Lewis acids. Also included is a section on Lewis acid-base secondary coordination sphere interactions, which can influence the reactivity of hydrides. Work from the past 50 years is included, but the majority of this Review focuses on research from the past decade, with the intent of showcasing the rapid emergence of this field and the potential for further development into the future. PMID:27164024

  7. EFFECTS OF ARGON ON THE PROPERTIES OF RF SPUTTERED AMORPHOUS SILICON

    OpenAIRE

    Shao-Qi, Peng; Qai, Yu; Xian, Zhang; Jing, Ye

    1981-01-01

    The Effects of argon on the properties of rf sputtered amorphous silicon film have been investigated. As the sputtering argon pressure is increased from 2 to 20 mTorr, the content of argon in the amorphous silicon film increases apparently (Argon/Silicon : from 10-2 to 5 x 10-2). The other properties measured as a function of argon pressure PAr show that as the PAr is increased, the photoconductivity, resistivity (300K), conductivity activation energy and optical gap increase also, while the ...

  8. Generalized computational model for high-pressure metal hydrides with variable thermal properties

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rokni, Masoud

    2015-01-01

    This study considers a detailed 1D fueling model applied to a metal hydride system, with Ti1.1CrMn as the absorbing alloy, to predict the weight fraction of the absorbed hydrogen and the solid bed temperature. Dependencies of thermal conductivity and specific heat capacity upon pressure...... and hydrogen content, respectively, are accounted for by interpolating experimental data. The effect of variable parameters on the critical metal hydride thickness is investigated and compared to results obtained from a constant-parameter analysis. Finally, the discrepancy in the metal hydride thickness value...

  9. Rapid Microwave Synthesis, Characterization and Reactivity of Lithium Nitride Hydride, Li4NH

    OpenAIRE

    Nuria Tapia-Ruiz; Natalie Sorbie; Nicolas Vaché; Hoang, Tuan K. A.; Gregory, Duncan H.

    2013-01-01

    Lithium nitride hydride, Li4NH, was synthesised from lithium nitride and lithium hydride over minute timescales, using microwave synthesis methods in the solid state for the first time. The structure of the microwave-synthesised powders was confirmed by powder X-ray diffraction [tetragonal space group I41/a; a = 4.8864(1) Å, c = 9.9183(2) Å] and the nitride hydride reacts with moist air under ambient conditions to produce lithium hydroxide and subsequently lithium carbonate. Li4NH undergoes n...

  10. Solid hydrides as hydrogen storage reservoirs; Hidruros solidos como acumuladores de hidrogeno

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, A.; Sanchez, C.; Friedrichs, O.; Ares, J. R.; Leardini, F.; Bodega, J.; Fernandez, J. F.

    2010-07-01

    Metal hydrides as hydrogen storage materials are briefly reviewed in this paper. Fundamental properties of metal-hydrogen (gas) system such as Pressure-Composition-Temperature (P-C-T) characteristics are discussed on the light of the metal-hydride thermodynamics. Attention is specially paid to light metal hydrides which might have application in the car and transport sector. The pros and cons of MgH{sub 2} as a light material are outlined. Researches in course oriented to improve the behaviour of MgH{sub 2} are presented. Finally, other very promising alternative materials such as Al compounds (alanates) or borohydrides as light hydrogen accumulators are also considered. (Author)

  11. Thermal decomposition kinetics of titanium hydride and Al alloy melt foaming process

    Institute of Scientific and Technical Information of China (English)

    YANG; Donghui; HE; Deping; YANG; Shangrun

    2004-01-01

    A temperature programmed decomposition (TPD) apparatus with metal tube structure, in which Ar is used as the carrier gas, is established and the TPD spectrum of titanium hydride is acquired. Using consulting table method (CTM), spectrum superposition method (SSM) and differential spectrum technique, TPD spectrum of titanium hydride is separated and a set of thermal decomposition kinetics equations are acquired. According to these equations, the relationship between decomposition quantity and time for titanium hydride at the temperature of 940 K is obtained and the result well coincides with the Al alloy melt foaming process.

  12. Proton beam production by a laser ion source with hydride target

    Energy Technology Data Exchange (ETDEWEB)

    Okamura, M., E-mail: okamura@bnl.gov [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Nishina Center for Accelerator-Based Science, RIKEN, Saitama (Japan); Stifler, C. [Engineering Physics Systems Department, Providence College, Providence, Rhode Island 02918 (United States); Palm, K. [Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Steski, D.; Kanesue, T. [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Ikeda, S. [Nishina Center for Accelerator-Based Science, RIKEN, Saitama (Japan); Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Kanagawa (Japan); Kumaki, M. [Nishina Center for Accelerator-Based Science, RIKEN, Saitama (Japan); Research Institute for Science and Engineering, Waseda University, Tokyo (Japan)

    2016-02-15

    We studied proton beam production from a laser ion source using hydrogen rich target materials. In general, gas based species are not suitable for laser ion sources since formation of a dense laser target is difficult. In order to achieve reliable operation, we tested hydride targets using a sub nanosecond Q-switched Nd-YAG laser, which may help suppress target material consumption. We detected enough yields of protons from a titanium hydride target without degradation of beam current during the experiment. The combination of a sub nanosecond laser and compressed hydride target may provide stable proton beam.

  13. Analytical control of production of As, P, Si, B hydrides and the mixtures on their basis

    International Nuclear Information System (INIS)

    Highly sensitive and selective detectors which are in the basis of some analytical devices, such as chromatograph Tzvet 500G attachment POU-80, gigrometer Enisej gas analyzer Platon that permit to control the production of As, P, Si, B hydrides, are tested. The techniques of tetermination of constant gases, general carbon, moisture in the mixtures based on As, P, Si, B hydrides with diluting gases (H2, He, Ar) as well as hydrides in them and in the air of working premises, are suggested

  14. Metal hydride hydrogen compression: recent advances and future prospects

    Science.gov (United States)

    Yartys, Volodymyr A.; Lototskyy, Mykhaylo; Linkov, Vladimir; Grant, David; Stuart, Alastair; Eriksen, Jon; Denys, Roman; Bowman, Robert C.

    2016-04-01

    Metal hydride (MH) thermal sorption compression is one of the more important applications of the MHs. The present paper reviews recent advances in the field based on the analysis of the fundamental principles of this technology. The performances when boosting hydrogen pressure, along with two- and three-step compression units, are analyzed. The paper includes also a theoretical modelling of a two-stage compressor aimed at describing the performance of the experimentally studied systems, their optimization and design of more advanced MH compressors. Business developments in the field are reviewed for the Norwegian company HYSTORSYS AS and the South African Institute for Advanced Materials Chemistry. Finally, future prospects are outlined presenting the role of the MH compression in the overall development of the hydrogen-driven energy systems. The work is based on the analysis of the development of the technology in Europe, USA and South Africa.

  15. Niche applications of metal hydrides and related thermal management issues

    Energy Technology Data Exchange (ETDEWEB)

    Lototskyy, M., E-mail: mlototskyy@uwc.ac.za [HySA Systems Competence Centre, South African Institute for Advanced Materials Chemistry, Faculty of Natural Sciences, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Satya Sekhar, B. [HySA Systems Competence Centre, South African Institute for Advanced Materials Chemistry, Faculty of Natural Sciences, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa); Muthukumar, P. [Mechanical Department, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Linkov, V.; Pollet, B.G. [HySA Systems Competence Centre, South African Institute for Advanced Materials Chemistry, Faculty of Natural Sciences, University of the Western Cape, Private Bag X17, Bellville 7535 (South Africa)

    2015-10-05

    Highlights: • MH H{sub 2} storage, compression & heat management: developments/thermal management. • Thermodynamic criteria for proper selection of MH for different gas phase applications. • Factors influencing on H{sub 2} charge/discharge dynamic performance and energy efficiency. • The improvement of MH heat transfer characteristics is crucial. • Ways of improvement of heat transfer in the MH systems. - Abstract: This short review highlights and discusses the recent developments and thermal management issues related to metal hydride (MH) systems for hydrogen storage, hydrogen compression and heat management (refrigeration, pump and upgrade, etc.). Special attention is paid to aligning the system features with the requirements of the specific application. The considered system features include the MH material, the MH bed on the basis of its corresponding MH container, as well as the layout of the integrated system.

  16. Crystal structure of the superconducting phase of sulfur hydride

    Science.gov (United States)

    Einaga, Mari; Sakata, Masafumi; Ishikawa, Takahiro; Shimizu, Katsuya; Eremets, Mikhail I.; Drozdov, Alexander P.; Troyan, Ivan A.; Hirao, Naohisa; Ohishi, Yasuo

    2016-09-01

    A superconducting critical temperature above 200 K has recently been discovered in H2S (or D2S) under high hydrostatic pressure. These measurements were interpreted in terms of a decomposition of these materials into elemental sulfur and a hydrogen-rich hydride that is responsible for the superconductivity, although direct experimental evidence for this mechanism has so far been lacking. Here we report the crystal structure of the superconducting phase of hydrogen sulfide (and deuterium sulfide) in the normal and superconducting states obtained by means of synchrotron X-ray diffraction measurements, combined with electrical resistance measurements at both room and low temperatures. We find that the superconducting phase is mostly in good agreement with the theoretically predicted body-centred cubic (bcc) structure for H3S. The presence of elemental sulfur is also manifest in the X-ray diffraction patterns, thus proving the decomposition mechanism of H2S to H3S + S under pressure.

  17. Pressure-induced transformations of molecular boron hydride

    CERN Document Server

    Nakano, S; Gregoryanz, E A; Goncharov, A F; Mao Ho Kwang

    2002-01-01

    Decaborane, a molecular boron hydride, was compressed to 131 GPa at room temperature to explore possible non-molecular phases in this system and their physical properties. Decaborane changed its colour from transparent yellow to orange/red above 50 GPa and then to black above 100 GPa, suggesting some transformations. Raman scattering and infrared (IR) absorption spectroscopy reveal significant structural changes. Above 100 GPa, B-B skeletal, B-H and B-H-B Raman/IR peaks gradually disappeared, which implies a transformation into a non-molecular phase in which conventional borane-type bonding is lost. The optical band gap of the material at 100 GPa was estimated to be about 1.0 eV.

  18. Niche applications of metal hydrides and related thermal management issues

    International Nuclear Information System (INIS)

    Highlights: • MH H2 storage, compression & heat management: developments/thermal management. • Thermodynamic criteria for proper selection of MH for different gas phase applications. • Factors influencing on H2 charge/discharge dynamic performance and energy efficiency. • The improvement of MH heat transfer characteristics is crucial. • Ways of improvement of heat transfer in the MH systems. - Abstract: This short review highlights and discusses the recent developments and thermal management issues related to metal hydride (MH) systems for hydrogen storage, hydrogen compression and heat management (refrigeration, pump and upgrade, etc.). Special attention is paid to aligning the system features with the requirements of the specific application. The considered system features include the MH material, the MH bed on the basis of its corresponding MH container, as well as the layout of the integrated system

  19. Final report for the DOE Metal Hydride Center of Excellence.

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Jay O.; Klebanoff, Leonard E.

    2012-01-01

    This report summarizes the R&D activities within the U.S. Department of Energy Metal Hydride Center of Excellence (MHCoE) from March 2005 to June 2010. The purpose of the MHCoE has been to conduct highly collaborative and multi-disciplinary applied R&D to develop new reversible hydrogen storage materials that meet or exceed DOE 2010 and 2015 system goals for hydrogen storage materials. The MHCoE combines three broad areas: mechanisms and modeling (which provide a theoretically driven basis for pursuing new materials), materials development (in which new materials are synthesized and characterized) and system design and engineering (which allow these new materials to be realized as practical automotive hydrogen storage systems). This Final Report summarizes the organization and execution of the 5-year research program to develop practical hydrogen storage materials for light duty vehicles. Major results from the MHCoE are summarized, along with suggestions for future research areas.

  20. Modelling zirconium hydrides using the special quasirandom structure approach

    KAUST Repository

    Wang, Hao

    2013-01-01

    The study of the structure and properties of zirconium hydrides is important for understanding the embrittlement of zirconium alloys used as cladding in light water nuclear reactors. Simulation of the defect processes is complicated due to the random distribution of the hydrogen atoms. We propose the use of the special quasirandom structure approach as a computationally efficient way to describe this random distribution. We have generated six special quasirandom structure cells based on face centered cubic and face centered tetragonal unit cells to describe ZrH2-x (x = 0.25-0.5). Using density functional theory calculations we investigate the mechanical properties, stability, and electronic structure of the alloys. © the Owner Societies 2013.

  1. Delayed hydride cracking: theoretical model testing to predict cracking velocity

    International Nuclear Information System (INIS)

    Pressure tubes from Candu nuclear reactors as any other component manufactured with Zr alloys are prone to delayed hydride cracking. That is why it is important to be able to predict the cracking velocity during the component lifetime from parameters easy to be measured, such as: hydrogen concentration, mechanical and microstructural properties. Two of the theoretical models reported in literature to calculate the DHC velocity were chosen and combined, and using the appropriate variables allowed a comparison with experimental results of samples from Zr-2.5 Nb tubes with different mechanical and structural properties. In addition, velocities measured by other authors in irradiated materials could be reproduced using the model described above. (author)

  2. Hydride Formation in Neutron Irradiated Material Under In Reactor Conditions

    International Nuclear Information System (INIS)

    The present is a brief summary of the three reports completed within the framework of the SPAR III project. The following is a resume of our aims, techniques used to achieve the objectives and conclusions attained under the guiding thread of the hydride formation in neutron irradiated zirconium alloys and other reactor in operating conditions. As is it known, under reactor operating conditions zirconium components go through transformations which affect their original microstructural and thermodynamical properties. Both concerns are starting points of many research lines for the zirconium alloys used in the nuclear power reactors. Regarding microstructural transformations, one of the most important topics is the phase stability of these alloys. To cite a well-known case, second phase particles of zircaloy-4 shown to be unstable under neutron radiation. Since such phases play a role in the corrosion rate control, this instability became a problem for high burnup fuel claddings design. Similar observations can be made about the β−Zr phase in the Zr-2.5Nb CANDU pressure tubes alloy. On the other hand, there are issues directly involved with thermodynamics, e.g., hydrogen behaviour and its role in the degradation processes of fuel assemblies and other zirconium alloys components, which showed to be affected by neutron radiation. Finally, applied stresses and thermal cycling are part of these operating conditions, which can be simulated performing experiments in situ which allows testing hydrogen solubility behaviour and hydride reorientation. In the context described above, the research topics proposed to SPAR III were aimed to improve the knowledge of these degradation processes. In this scheme, zircaloy-4 which remained more than ten years at full power operation and virgin unirradiated zirconium alloys were suited by the more improved micro analytical techniques to characterize microstructural transformations cited above

  3. Narrow spectral width laser diode for metastable argon atoms pumping

    Science.gov (United States)

    Gao, Jun; Li, Bin; Wang, Xinbing; Zuo, Duluo

    2016-03-01

    Diode laser pump source with narrow emitting spectrum for optically pumped metastable rare gas laser (OPRGL) of argon was achieved by employing a complex external cavity coupled with volume Bragg grating (VBG). A commercially available c-mount laser diode with rated power of 6 W was used and studied in both the free running mode and VBG external cavity. The maximum output power of 3.9 W with FWHM less than 25 pm and peak wavelength locked around 811.53 nm was obtained from the VBG external cavity laser diode. Precise control of VBG temperature enabled fine tuning of the emission wavelength over a range of 450 pm. Future researches on OPRGL of argon will benefit from it.

  4. Evaporation and condensation at a liquid surface. I. Argon

    Science.gov (United States)

    Yasuoka, Kenji; Matsumoto, Mitsuhiro; Kataoka, Yosuke

    1994-11-01

    Molecular dynamics computer simulations were carried out to investigate the dynamics of evaporation and condensation for argon at the temperature of 80 and 100 K. From the decrease of the survival probability of vapor molecules, the ratio of self reflection to collision is estimated to be 12%-15%, only weakly dependent on the temperature. This suggests that argon vapor molecules are in the condition of almost complete capture, and the condensation is considered to be a barrierless process. The total ratio of reflection which is evaluated with the flux correlation of condensation and evaporation is 20% at both temperature. The difference between these two ratios of reflection is ascribed to a phenomenon that vapor molecules colliding with the surface drive out other liquid molecules. This molecule exchange at the surface is as important as the self-reflection, and the conventional picture of condensation as a unimolecular chemical reaction is not appropriate.

  5. The Erosion of Frozen Argon by Swift Helium Ions

    DEFF Research Database (Denmark)

    Besenbacher, F.; Bøttiger, Jørgen; Graversen, O.;

    1981-01-01

    The temperature, energy, and thickness dependence of the erosion rates of frozen argon films when irradiated with 0.1–3 MeV helium ions have been measured. The erosion yields Y are much too high to be explained by the concentional collisional cascade-sputtering theory and are furthermore unequivo......The temperature, energy, and thickness dependence of the erosion rates of frozen argon films when irradiated with 0.1–3 MeV helium ions have been measured. The erosion yields Y are much too high to be explained by the concentional collisional cascade-sputtering theory and are furthermore...... unequivocally associated with electronic processes generated by the bombarding particle. In the present energy region, it is found that Y scales approximately as the electronic stopping power squared, depends on the charge state of the incoming helium ions, and perhaps more important, is independent...

  6. Demonstration of a Lightguide Detector for Liquid Argon TPCs

    CERN Document Server

    Bugel, L; Ignarra, C; Jones, B J P; Katori, T; Smidt, T; Tanaka, H -K

    2011-01-01

    We report demonstration of light detection in liquid argon using an acrylic lightguide detector system. This opens the opportunity for development of an inexpensive, large-area light collection system for large liquid argon time projection chambers. The guides are constructed of acrylic, with TPB embedded in a surface coating with a matching index of refraction. We study the response to early scintillation light produced by a 5.3 MeV alpha. We measure coating responses from 7 to 8 PE on average, compared to an ideal expectation of 10 PE on average. We estimate the attenuation length of light along the lightguide bar to be greater than 0.5 m. The coating response and the attenuation length can be improved; we show, however, that these results are already sufficient for triggering in a large detector.

  7. Trimming a Metallic Biliary Stent Using an Argon Plasma Coagulator

    International Nuclear Information System (INIS)

    Background. Distal migration is one of the common complications after insertion of a covered metallic stent. Stent repositioning or removal is not always possible in every patient. Therefore, trimming using an argon plasma coagulator (APC) may be a good alternative method to solve this problem. Methods. Metallic stent trimming by APC was performed in 2 patients with biliary Wallstent migration and in another patient with esophageal Ultraflex stent migration. The power setting was 60-100 watts with an argon flow of 0.8 l/min. Observations. The procedure was successfully performed and all distal parts of the stents were removed. No significant collateral damage to the nearby mucosa was observed. Conclusions. In a patient with a distally migrated metallic stent, trimming of the stent is possible by means of an APC. This new method may be applicable to other sites of metallic stent migration

  8. Readiness of the ATLAS Liquid Argon Calorimeter for LHC Collisions

    CERN Document Server

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Seidel, S C; Seiden, A; Seifert, F; Seixas, J M; Sekhniaidze, G; Seliverstov, D M; Sellden, B; Seman, M; Semprini-Cesari, N; Serfon, C; Serin, L; Seuster, R; Severini, H; Sevior, M E; Sfyrla, A; Shamim, M; Shan, L Y; Shank, J T; Shao, Q T; Shapiro, M; Shatalov, P B; Shaver, L; Shaw, C; Shaw, K; Sherman, D; Sherwood, P; Shibata, A; Shimojima, M; Shin, T; Shmeleva, A; Shochet, M J; Shupe, M A; Sicho, P; Sidoti, A; Siebel, A; Siegert, F; Siegrist, J; Sijacki, Dj; Silbert, O; Silva, J; Silver, Y; Silverstein, D; Silverstein, S B; Simak, V; Simic, Lj; Simion, S; Simmons, B; Simonyan, M; Sinervo, P; Sinev, N B; Sipica, V; Siragusa, G; Sisakyan, A N; Sivoklokov, S Yu; Sjoelin, J; Sjursen, T B; Skubic, P; Skvorodnev, N; Slater, M; Slavicek, T; Sliwa, K; Sloper, J; Sluka, T; Smakhtin, V; Smirnov, S Yu; Smirnov, Y; Smirnova, L N; Smirnova, O; Smith, B C; Smith, D; Smith, K M; Smizanska, M; Smolek, K; Snesarev, A A; Snow, S W; Snow, J; Snuverink, J; Snyder, S; Soares, M; Sobie, R; Sodomka, J; Soffer, A; Solans, C A; Solar, M; Solfaroli-Camillocci, E; Solodkov, A A; Solovyanov, O V; Soluk, R; Sondericker, J; Sopko, V; Sopko, B; Sosebee, M; Sosnovtsev, V V; Sospedra-Suay, L; Soukharev, A; Spagnolo, S; Spanò, F; Speckmayer, P; Spencer, E; Spighi, R; Spigo, G; Spila, F; Spiwoks, R; Spousta, M; Spreitzer, T; Spurlock, B; St Denis, R D; Stahl, T; Stamen, R; Stancu, S N; Stanecka, E; Stanek, R W; Stanescu, C; Stapnes, S; Starchenko, E A; Stark, J; Staroba, P; Starovoitov, P; Stastny, J; Staude, A; Stavina, P; Stavropoulos, G; Steinbach, P; Steinberg, P; Stekl, I; Stelzer, B; Stelzer, H J; Stelzer-Chilton, O; Stenzel, H; Stevenson, K; Stewart, G; Stockton, M C; Stoerig, K; Stoicea, G; Stonjek, S; Strachota, P; Stradling, A; Straessner, A; Strandberg, J; Strandberg, S; Strandlie, A; Strauss, M; Strizenec, P; Ströhmer, R; Strom, D M; Strong, J A; Stroynowski, R; Strube, J; Stugu, B; Stumer, I; Soh, D A; Su, D; Suchkov, S I; Sugaya, Y; Sugimoto, T; Suhr, C; Suk, M; Sulin, V V; Sultansoy, S; Sumida, T; Sun, X; Sundermann, J E; Suruliz, K; Sushkov, S; Susinno, G; Sutton, M R; Suzuki, T; Suzuki, Y; Sviridov, Yu M; Sykora, I; Sykora, T; Szymocha, T; Sánchez, J; Ta, D; Tackmann, K; Taffard, A; Tafirout, R; Taga, A; Takahashi, Y; Takai, H; Takashima, R; Takeda, H; Takeshita, T; Talby, M; Talyshev, A; Tamsett, M C; Tanaka, J; Tanaka, R; Tanaka, S; Tanaka, S; Tappern, G P; Tapprogge, S; Tardif, D; Tarem, S; Tarrade, F; Tartarelli, G F; Tas, P; Tasevsky, M; Tassi, E; Taylor, C; Taylor, F E; Taylor, G N; Taylor, R P; Taylor, W; Teixeira-Dias, P; Ten Kate, H; Teng, P K; Terada, S; Terashi, K; Terron, J; Terwort, M; Testa, M; Teuscher, R J; Tevlin, C M; Thadome, J; Thananuwong, R; Thioye, M; Thoma, S; Thomas, J P; Thomas, T L; Thompson, E N; Thompson, P D; Thompson, P D; Thompson, R J; Thompson, A S; Thomson, E; Thun, R P; Tic, T; Tikhomirov, V O; Tikhonov, Y A; Timmermans, C J W P; Tipton, P; Tique-Aires-Viegas, F J; Tisserant, S; Tobias, J; Toczek, B; Todorov, T; Todorova-Nova, S; Toggerson, B; Tojo, J; Tokár, S; Tokushuku, K; Tollefson, K; Tomasek, L; Tomasek, M; Tomasz, F; Tomoto, M; Tompkins, D; Tompkins, L; Toms, K; Tong, G; Tonoyan, A; Topfel, C; Topilin, N D; Torrence, E; Torró Pastor, E; Toth, J; Touchard, F; Tovey, D R; Tovey, S N; Trefzger, T; Tremblet, L; Tricoli, A; Trigger, I M; Trincaz-Duvoid, S; Trinh, T N; Tripiana, M F; Triplett, N; Trivedi, A; Trocmé, B; Troncon, C; Trzupek, A; Tsarouchas, C; Tseng, J C-L; Tsiafis, I; Tsiakiris, M; Tsiareshka, P V; Tsionou, D; Tsipolitis, G; Tsiskaridze, V; Tskhadadze, E G; Tsukerman, I I; Tsulaia, V; Tsung, J-W; Tsuno, S; Tsybychev, D; Turala, M; Turecek, D; Turk Cakir, I; Turlay, E; Tuts, P M; Twomey, M S; Tylmad, M; Tyndel, M; Tzanakos, G; Uchida, K; Ueda, I; Uhlenbrock, M; Uhrmacher, M; Ukegawa, F; Unal, G; Underwood, D G; Undrus, A; Unel, G; Unno, Y; Urbaniec, D; Urkovsky, E; Urquijo, P; Urrejola, P; Usai, G; Uslenghi, M; Vacavant, L; Vacek, V; Vachon, B; Vahsen, S; Valenta, J; Valente, P; Valentinetti, S; Valkar, S; Valladolid Gallego, E; Vallecorsa, S; Valls Ferrer, J A; Van Berg, R; van der Graaf, H; van der Kraaij, E; van der Poel, E; Van Der Ster, D; van Eldik, N; van Gemmeren, P; van Kesteren, Z; van Vulpen, I; Vandelli, W; Vandoni, G; Vaniachine, A; Vankov, P; Vannucci, F; Varela Rodriguez, F; Vari, R; Varnes, E W; Varouchas, D; Vartapetian, A; Varvell, K E; Vasilyeva, L; Vassilakopoulos, V I; Vazeille, F; Vegni, G; Veillet, J J; Vellidis, C; Veloso, F; Veness, R; Veneziano, S; Ventura, A; Ventura, D; Venturi, M; Venturi, N; Vercesi, V; Verducci, M; Verkerke, W; Vermeulen, J C; Vetterli, M C; Vichou, I; Vickey, T; Viehhauser, G H A; Villa, M; Villani, E G; Villaplana Perez, M; Villate, J; Vilucchi, E; Vincter, M G; Vinek, E; Vinogradov, V B; Viret, S; Virzi, J; Vitale, A; Vitells, O V; Vivarelli, I; Vives Vaques, F; Vlachos, S; Vlasak, M; Vlasov, N; Vogt, H; Vokac, P; Volpi, M; Volpini, G; von der Schmitt, H; von Loeben, J; von Radziewski, H; von Toerne, E; Vorobel, V; Vorobiev, A P; Vorwerk, V; Vos, M; Voss, R; Voss, T T; 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Winklmeier, F; Wittgen, M; Wolter, M W; Wolters, H; Wosiek, B K; Wotschack, J; Woudstra, M J; Wraight, K; Wright, C; Wright, D; Wrona, B; Wu, S L; Wu, X; Wulf, E; Xella, S; Xie, S; Xie, Y; Xu, D; Xu, N; Yamada, M; Yamamoto, A; Yamamoto, S; Yamamura, T; Yamanaka, K; Yamaoka, J; Yamazaki, T; Yamazaki, Y; Yan, Z; Yang, H; Yang, U K; Yang, Y; Yang, Z; Yao, W-M; Yao, Y; Yasu, Y; Ye, J; Ye, S; Yilmaz, M; Yoosoofmiya, R; Yorita, K; Yoshida, R; Young, C; Youssef, S P; Yu, D; Yu, J; Yu, M; Yu, X; Yuan, J; Yuan, L; Yurkewicz, A; Zaidan, R; Zaitsev, A M; Zajacova, Z; Zambrano, V; Zanello, L; Zarzhitsky, P; Zaytsev, A; Zeitnitz, C; Zeller, M; Zema, P F; Zemla, A; Zendler, C; Zenin, O; Zenis, T; Zenonos, Z; Zenz, S; Zerwas, D; Zevi della Porta, G; Zhan, Z; Zhang, H; Zhang, J; Zhang, Q; Zhang, X; Zhao, L; Zhao, T; Zhao, Z; Zhemchugov, A; Zheng, S; Zhong, J; Zhou, B; Zhou, N; Zhou, Y; Zhu, C G; Zhu, H; Zhu, Y; Zhuang, X; Zhuravlov, V; Zilka, B; Zimmermann, R; Zimmermann, S; Zimmermann, S; Ziolkowski, M; Zitoun, R; Zivkovic, L; Zmouchko, V V; Zobernig, G; Zoccoli, A; zur Nedden, M; Zutshi, V

    2010-01-01

    The ATLAS liquid argon calorimeter has been operating continuously since August 2006. At this time, only part of the calorimeter was readout, but since the beginning of 2008, all calorimeter cells have been connected to the ATLAS readout system in preparation for LHC collisions. This paper gives an overview of the liquid argon calorimeter performance measured in situ with random triggers, calibration data, cosmic muons, and LHC beam splash events. Results on the detector operation, timing performance, electronics noise, and gain stability are presented. High energy deposits from radiative cosmic muons and beam splash events allow to check the intrinsic constant term of the energy resolution. The uniformity of the electromagnetic barrel calorimeter response along eta (averaged over phi) is measured at the percent level using minimum ionizing cosmic muons. Finally, studies of electromagnetic showers from radiative muons have been used to cross-check the Monte Carlo simulation. The performance results obtained u...

  9. Breakdown voltage of metal-oxide resistors in liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Bagby, L. F. [Fermilab; Gollapinni, S. [Kansas State U.; James, C. C. [Fermilab; Jones, B. J.P. [MIT; Jostlein, H. [Fermilab; Lockwitz, S. [Fermilab; Naples, D. [Pittsburgh U.; Raaf, J. L. [Fermilab; Rameika, R. [Fermilab; Schukraft, A. [Fermilab; Strauss, T. [Bern U., LHEP; Weber, M. S. [Bern U., LHEP; Wolbers, S. A. [Fermilab

    2014-11-07

    We characterized a sample of metal-oxide resistors and measured their breakdown voltage in liquid argon by applying high voltage (HV) pulses over a 3 second period. This test mimics the situation in a HV-divider chain when a breakdown occurs and the voltage across resistors rapidly rise from the static value to much higher values. All resistors had higher breakdown voltages in liquid argon than their vendor ratings in air at room temperature. Failure modes range from full destruction to coating damage. In cases where breakdown was not catastrophic, subsequent breakdown voltages were lower in subsequent measuring runs. One resistor type withstands 131 kV pulses, the limit of the test setup.

  10. A pressurized argon gas TPC as DUNE near detector

    CERN Document Server

    Martin-Albo, J

    2016-01-01

    DUNE is a new international experiment for neutrino physics and nucleon decay searches. It will consist of two detectors, about 1300 km apart, exposed to a multi-megawatt neutrino beam that will be built at Fermilab. One of the two detectors will be installed several hundred meters downstream of the neutrino production point with the primary role of characterising the energy spectrum and composition of the beam as well as performing precision measurements of neutrino cross sections. For the design of this so-called near detector, the DUNE Collaboration is considering, among other technologies, a pressurized argon gas time projection chamber. Such a detector, thanks to its low density and low detection thresholds, would allow the detailed measurement in argon of nuclear effects at the neutrino interaction vertex, which are considered at present one of the most important sources of systematic uncertainty for neutrino oscillation measurements.

  11. Opacity measurements in shock-generated argon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D.

    1993-07-01

    Dense plasmas having uniform and constant density and temperature are generated by passage of a planar shock wave through gas. The opacity of the plasma is accurately measured versus wavelength by recording the risetime of emitted light. This technique is applicable to a wide variety of species and plasma conditions. Initial experiments in argon have produced plasmas with 2 eV temperatures, 0.004--0.04 g/cm{sup 3} densities, and coupling parameters {Gamma} {approximately}0.3--0.7. Measurements in visible light are compared with calculations using the HOPE code. An interesting peak in the capacity at 400 nm is observed for the first time and is identified with the 4s-5p transition in excited neutral argon atoms.

  12. Treatment of facial vascular lesions with an argon laser

    Science.gov (United States)

    Szymanczyk, Jacek; Golebiowska, Aleksandra; Michalska, I.

    1996-03-01

    Two-hundred-ninety-six patients with various vascular lesions of the face have been treated with argon laser LAK-1 in the Department of Dermatology Warsaw Medical Academy since April 1992. The diagnosis of the treated lesions was port-wine stains, multiple telangiectasiae and small, most often induced by trauma hemangioma cavernosum of the lip. Best results were achieved in the patients with small hemangiomas cavernosum of the lip and multiple telangiectasiae on the face. Cure rate in this group was 100%. In 112 port-wine stain cases fading of 50 - 75% comparing with the adjacent skin was achieved. With stress, the argon laser therapy is a method of choice for the treatment of hemangioma cavernosum, port-wine stains and multiple teleagiectasiae of the face.

  13. Development of cryogenic installations for large liquid argon neutrino detectors

    CERN Document Server

    Adamowski, M; Geynisman, M; Hentschel, S; Montanari, D; Nessi, M; Norris, B

    2015-01-01

    A proposal for a very large liquid argon (68,000 kg) based neutrino detector is being studied. To validate the design principles and the detector technology, and to gain experience in the development of the cryostats and the cryogenic systems needed for such large experiments, several smaller scale installations will be developed and implemented, at Fermilab and CERN. The cryogenic systems for these installations will be developed, constructed, installed and commissioned by an international engineering team. These installations shall bring the required cooling power under specific conditions to the experiments for the initial cool-down and the long term operation, and shall also guarantee the correct distribution of the cooling power within the cryostats to ensure a homogeneous temperature distribution within the cryostat itself. The cryogenic systems shall also include gaseous and liquid phase argon purification devices to be used to reach and maintain the very stringent purity requirements needed for these...

  14. Spectroscopy of Argon Excited in an Electron Beam Ion Trap

    Energy Technology Data Exchange (ETDEWEB)

    Trabert, E

    2005-04-18

    Argon is one of the gases best investigated and most widely used in plasma discharge devices for a multitude of applications that range from wavelength reference standards to controlled fusion experiments. Reviewing atomic physics and spectroscopic problems in various ionization stages of Ar, the past use and future options of employing an electron beam ion trap (EBIT) for better and more complete Ar data in the x-ray, EUV and visible spectral ranges are discussed.

  15. Influence of argon pollution on the weld surface morphology

    OpenAIRE

    Krolczyk, G.M.; Nieslony, P.; Krolczyk, J.B.; I. Samardzic; Legutko, S.; S. Hloch; Barrans, Simon; Maruda, R.W.

    2015-01-01

    In this paper the surfaces of butt welded joints in steel tubes were analyzed using an optical 3D measurement system to determine the morphology and topographic parameters. It was established that pollution of the argon shield gas with oxygen did not influence the width of the heat-affected zone. However, the composition of the shield gas significantly influenced the surface asymmetry, Ssk, and its inclination Sku. The measurement of these parameters enabled the selection of a ...

  16. STATUS OF THE ATLAS LIQUID ARGON CALORIMETER AND ITS PERFORMANCE

    CERN Document Server

    Berillari, T; The ATLAS collaboration

    2011-01-01

    The liquid argon (LAr) calorimeters are used in ATLAS for all electromagnetic and for hadron calorimetry. The LAr calorimeter system consists of an electromagnetic barrel calorimeter and two endcaps with electromagnetic, hadronic and forward calorimeters. The latest status of the detector as well as problems and solutions addressed during the last years will be presented. Aspects of operation of a large detector over a long time period will be summarized and selected topics showing the performance of the detector will be shown.

  17. Thermal decomposition of lanthanum(III) butyrate in argon atmosphere

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Yue, Zhao; Xiao, Tang;

    2013-01-01

    The thermal decomposition of La(C3H7CO2)3·xH2O (x≈0.82) was studied in argon during heating at 5K/min. After the loss of bound H2O, the anhydrous butyrate presents at 135°C a phase transition to a mesophase, which turns to an isotropic liquid at 180°C. The decomposition of the anhydrous butyrate ...

  18. Operational performance of a large liquid argon photon calorimeter

    International Nuclear Information System (INIS)

    We describe the performance of a large (0.9x1.4 m2) liquid argon photon calorimeter in high energy experiments at Fermilab. Resolutions for π0 and electron showers, obtained under data-taking conditions, are compared with electron-beam calibration results. Exceptional spatial and time resolutions have been achieved for isolated showers (sigmasub(x,y)0 data up to 180 GeV are presented. (orig.)

  19. Unified set of atomic transition probabilities for neutral argon

    OpenAIRE

    Wiese, W.; Brault, J.; Danzmann, K.; Helbig, V.; de Kock, M

    1989-01-01

    The atomic transition probabilities and radiative lifetimes of neutral argon have been the subject of numerous experiments and calculations, but the results exhibit many discrepancies and inconsistencies. We present a unified set of atomic transition probabilities, which is consistent with essentially all recent results, albeit sometimes only after critical reanalysis. The data consistency and scale confirmation has been achieved in two ways. (i) We have carried out some lifetime–branching-ra...

  20. Monte Carlo Simulation of Argon in Nano-Space

    Institute of Scientific and Technical Information of China (English)

    CHEN Min; YANG Chun; GUO Zeng-Yuan

    2000-01-01

    Monte Carlo simulations are performed to investigate the thermodynamic properties of argon confined in nano-scale cubes constructed of graphite walls. A remarkable depression of the system pressures is observed. The simulations reveal that the length-scale of the cube, the magnitude of the interaction between the fluid and the graphite wall and the density of the fluid exhibit reasonable effects on the thermodynamic property shifts of the luid.

  1. Heat transfer characteristics of the metal hydride vessel based on the plate-fin type heat exchanger

    Science.gov (United States)

    Oi, Tsutomu; Maki, Kohei; Sakaki, Yoshinori

    Heat transfer characteristics of the metal hydride vessel based on the plate-fin type heat exchanger were investigated. Metal hydride beds were filled with AB 2 type hydrogen-storage alloy's particles, Ti 0.42Zr 0.58Cr 0.78Fe 0.57Ni 0.2Mn 0.39Cu 0.03, with a storage capacity of 0.92 wt.%. Heat transfer model in the metal hydride bed based on the heat transfer mechanism for packed bed proposed by Kunii and co-workers is presented. The time-dependent hydrogen absorption/desorption rate and pressure in the metal hydride vessel calculated by the model were compared with the experimental results. During the hydriding, calculated hydrogen absorption rates agreed with measured ones. Calculated thermal equilibrium hydrogen pressures were slightly lower than the measured hydrogen pressures at the inlet of metal hydride vessel. Taking account of the pressure gradient between the inlet of metal hydride vessel and the metal hydride bed, it is considered that this discrepancy is reasonable. During the dehydriding, there were big differences between the calculated hydrogen desorption rates and measured ones. As calculated hydrogen desorption rates were lower than measured ones, there were big differences between the calculated thermal equilibrium hydrogen pressures and the measured hydrogen pressures at the inlet of metal hydride vessel. It is considered that those differences are due to the differences of the heat transfer characteristics such as thermal conductivity of metal hydride particles and porosity between the assumed and actual ones. It is important to obtain the heat transfer characteristics such as thermal conductivity of metal hydride particles and porosity both during the hydriding and dehydriding to design a metal hydride vessel.

  2. Catalytic Radical Reduction in Aqueous Solution by a Ruthenium Hydride Intermediate.

    Science.gov (United States)

    Htet, Yamin; Tennyson, Andrew G

    2016-07-18

    Some manganese complexes can catalyze both antioxidant and pro-oxidant reactions, whereby the disparate reactivity modes are determined by the catalyst environment and afford distinct therapeutic effects. We recently reported the reduction of radicals in buffered aqueous solution catalyzed by a ruthenium complex with biologically relevant non-tertiary alcohols as terminal reductants. Mechanistic evidence is presented, indicating that this catalytic radical reduction is achieved by a Ru-hydride intermediate formed by β-hydride elimination from a Ru-alkoxide species. A similar mechanism and Ru-hydride intermediate was previously reported to kill cancer cells with catalytic pro-oxidant effects. Therefore, our demonstration of catalytic antioxidant effects by the same type of intermediate reveals new potential therapeutic strategies and applications for catalytic systems that form Ru-hydride intermediates. PMID:27254303

  3. In situ probing of surface hydrides on hydrogenated amorphous silicon using attenuated total reflection infrared spectroscopy

    CERN Document Server

    Kessels, W M M; Sanden, M C M; Aydil, E S

    2002-01-01

    An in situ method based on attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) is presented for detecting surface silicon hydrides on plasma deposited hydrogenated amorphous silicon (a-Si:H) films and for determining their surface concentrations. Surface silicon hydrides are desorbed by exposing the a-Si:H films to low energy ions from a low density Ar plasma and by comparing the infrared spectrum before and after this low energy ion bombardment, the absorptions by surface hydrides can sensitively be separated from absorptions by bulk hydrides incorporated into the film. An experimental comparison with other methods that utilize isotope exchange of the surface hydrogen with deuterium showed good agreement and the advantages and disadvantages of the different methods are discussed. Furthermore, the determination of the composition of the surface hydrogen bondings on the basis of the literature data on hydrogenated crystalline silicon surfaces is presented, and quantification of the h...

  4. Hydride precipitation kinetics in Zircaloy-4 studied using synchrotron X-ray diffraction

    Science.gov (United States)

    Courty, Olivier F.; Motta, Arthur T.; Piotrowski, Christopher J.; Almer, Jonathan D.

    2015-06-01

    As a result of in-reactor corrosion during operation in nuclear reactors, hydrogen can enter the zirconium fuel cladding and precipitate as brittle hydride particles, which may reduce cladding ductility. Dissolved hydrogen responds to temperature gradients, resulting in transport and precipitation into cold spots so that the distribution of hydrides in the cladding is inhomogeneous. The hydrogen precipitation kinetics plays a strong role in the spatial distribution of the hydrides in the cladding. The precipitation rate is normally described as proportional to the supersaturation of hydrogen in solid solution. The proportionality constant, α2, for hydride precipitation in Zircaloy-4 is measured directly using in situ synchrotron X-Ray diffraction, at different temperatures and with three different initial hydrogen concentrations. The results validate the linear approximation of the phenomenological model and a near constant value of α2 = 4.5 × 10-4 s-1 was determined for the temperature range studied.

  5. The microstructure and hydriding characteristics of high temperature aged U-13 at.%Nb alloy

    Science.gov (United States)

    Ji, Hefei; Shi, Peng; Li, Ruiwen; Jiang, Chunli; Yang, Jiangrong; Hu, Guichao

    2015-09-01

    Niobium as alloying element significantly improves physical and chemical properties of metallic uranium, exhibiting great application potential in uranium alloy materials. The corrosion resistance performance as well as the internal alloy phase structure of uranium-niobium alloy is closely related to aging processes. Microstructure and hydriding characteristics of the 400 °C/9 h + 500 °C/2 h aged uranium-13 at.% niobium alloys (U-13 at.%Nb) were investigated from the point of view of relationship between the microstructure and growth of the hydriding areas. The microstructure, morphology and composition of the alloy phases before and after the hydriding were well characterized by the laser scanning confocal microscopy (LSCM), scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Experimental results indicated that the hydrogen preferentially reacted with the Nb-depleted phase α-like-U to form monolithic β-UH3Nbx, and the alloy microstructure played an important role in hydride growth.

  6. The two steps thermal decomposition of titanium hydride and two steps foaming of Al alloy

    Institute of Scientific and Technical Information of China (English)

    SHANG Jintang; HE Deping

    2005-01-01

    Two steps foaming (TSF) technique was proposed to prepare shaped Al alloy foam. Based on the thermal decomposition kinetics equation of titanium hydride, the relationship between two steps thermal decomposition kinetics of titanium hydride and two steps foaming Al alloy melt was studied. Two steps thermal decomposition curve of titanium hydride under increasing and constant temperature was calculated respectively. The hydrogen mass needed in the second foaming step was also calculated. Results showed that the hydrogen mass of the second thermal decomposition of titanium hydride is enough for the second foaming step in the condition of as-received Al melt foaming. Experimental and theoretical results indicate that two steps foaming technique can be used to prepare Al alloy foam with high porosity, shaped components and sandwich with Al alloy foam core.

  7. Two dimensional condensation of argon adsorbed on lamellar halides

    International Nuclear Information System (INIS)

    Lamellar halides such as NiCl2, FeCl2, NiBr2, MnBr2, MgBr2, CdBr2, CoI2, FeI2, MnI2, CaI2 and PbI2 were sublimed in a rapid stream of dry nitrogen. The adsorption of argon on such materials shows stepped isotherms which reveal two dimensional condensations. From sets of isotherms the Helmholtz free energy, the internal energy and the entropy of the successive layers are determined. From the entropy of the first layer the role of the potential relief of the adsorbent surface on the structure of the adsorbed layer may be determined while the Helmholtz free energy reveals how the ionic character of the adsorbent governs the attractive force of adsorption. The study of the second third and fourth layers shows that their growth follows quite a different behaviour depending on whether the Van der Waals diameter of argon is greater or smaller than the distance between adjacent anions on the crystal surface. A proposition is made to account for the difference in the critical temperatures of the first and second dense layers in terms of the vibrationnal state of their respective substrate. The occurence for the maximum critical temperature observed of corresponding to a triangular layer 3% more expanded than the (111) plane of solid argon is discussed

  8. A liquid argon scintillation veto for the Gerda experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wegmann, Anne [Max-Planck Institut fuer Kernphysik, Heidelberg (Germany); Collaboration: GERDA-Collaboration

    2013-07-01

    Gerda is an experiment to search for the neutrinoless double beta decay of {sup 76}Ge. Bare germanium detectors are operated in a cryostat with 65 m{sup 3} of liquid argon (LAr). To reach the aspired background index of ≤10{sup -3} cts/(keV.kg.yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). A light instrumentation of LAr installed in the LArGe test facility has demonstrated that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. Based on these results, Gerda pursues several options for the light instrumentation, which have to be compatible with the stringent radiopurity requirements of the experiment and should provide a significant suppression of the background in the region of interest around Q{sub ββ} at 2039 keV. This talk gives an account of the competing design options under investigation in the Gerda collaboration. The design options using photomultiplier tubes (PMT) and silicon photomultipliers (SiPM) are discussed, together with their expected performance from Monte Carlo simulations. In addition, the progress of development is reported, along with the design criteria for light instrumentation in Gerda.

  9. A liquid argon scintillation veto for the Gerda experiment

    International Nuclear Information System (INIS)

    Gerda is an experiment to search for the neutrinoless double beta decay of 76Ge. Bare germanium detectors are operated in a cryostat with 65 m3 of liquid argon (LAr). To reach the aspired background index of ≤10-3 cts/(keV.kg.yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). A light instrumentation of LAr installed in the LArGe test facility has demonstrated that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. Based on these results, Gerda pursues several options for the light instrumentation, which have to be compatible with the stringent radiopurity requirements of the experiment and should provide a significant suppression of the background in the region of interest around Qββ at 2039 keV. This talk gives an account of the competing design options under investigation in the Gerda collaboration. The design options using photomultiplier tubes (PMT) and silicon photomultipliers (SiPM) are discussed, together with their expected performance from Monte Carlo simulations. In addition, the progress of development is reported, along with the design criteria for light instrumentation in Gerda.

  10. Space-charge effects in liquid argon ionization chambers

    Science.gov (United States)

    Rutherfoord, J. P.; Walker, R. B.

    2015-03-01

    We have uniformly irradiated liquid argon ionization chambers with betas from high-activity 90Sr sources. The radiation environment is similar to that in the liquid argon calorimeters which are part of the ATLAS detector installed at CERN's Large Hadron Collider (LHC). We measured the resulting ionization current over a wide range of applied potential for two different source activities and for three different chamber gaps. These studies provide operating experience at exceptionally high ionization rates. In particular they indicate a stability at the 0.1% level for these calorimeters over years of operation at the full LHC luminosity when operated in the normal mode at an electric field E = 1.0 kV / mm. We can operate these chambers in the normal mode or in the space-charge limited regime and thereby determine the transition point between the two. This transition point is parameterized by a positive argon ion mobility of μ+ = 0.08 ± 0.02mm2 / V s at a temperature of 88.0±0.5 K and at a pressure of 1.02±0.02 bar. In the space-charge limited regime the ionization currents are degraded and show signs of instability. At the highest electric fields in our study (6.7 kV/mm) the ionization current is still slowly rising with increasing electric field.

  11. ARAPUCA a new device for liquid argon scintillation light detection

    International Nuclear Information System (INIS)

    We present a totally innovative device for the detection of liquid argon scintillation light, that has been named ARAPUCA (Argon R and D Advanced Program at UniCAmp). It is composed of a passive light collector and of active devices. The latters are standard SiPMs that operate at liquid argon temperature, while the passive collector is based on a new technology, never explored in this field before. It is a photon trap, that allows to collect light with extremely high efficiency. The total detection efficiency of the device can be tuned by modifying the ratio between the area of the active devices (SiPM) and the area of the optical window. For example, it will allow to reach a detection efficiency at the level of 1% on a surface of 50 × 50 cm2 with an active coverage of 2 × 2 cm2 (two/three large area SiPM). It is also a cheap device, since the major part of its cost is represented by the active devices. For these reason this appears to be the ideal device for scintillation light detection in large Time Projection Chambers. With appropriate modifications it can be used also in next generation Dark Matter detectors

  12. Isotopic fractionation of argon during stepwise release from shungite

    International Nuclear Information System (INIS)

    In previous attempts to determine the 40Ar/36Ar ratio in the ancient atmosphere, the only direct measurement yielding a value below the atmospheric value of today is for argon released at low temperatures from a pre-Cambrian shungite, an amorphous carbon mineral The present work confirms a low value for 40Ar/36Ar in gas released from a type I shungite at low temperatures. But quantitative scrutiny of the accompanying 38AR/36Ar ratios and the enhanced ratio of 40Ar/36Ar for the fractions released at high temperatures shows convincingly that the effect seen here is an artifact of the stepwise heating and the argon diffusion mobilized thereby. The low 40Ar/36Ar previously obtained is very likely from the same cause rather than reflecting the isotopic composition of the pre-Cambrian atmosphere. The vitreous character of and the sharp, conchoidal fractures seen in the specimens of type I shungite suggest that the substance may exhibit simple volume diffusion over macroscopic dimensions as glasses do. If so, the diffusion parameters (D infinitely = 3 x 10-4 cm2/s and E = 11 kcal/mole) obtained from the data imply rapid exchange with the atmosphere for any argon initially trapped in centimenter-thick veins of the material. (orig.)

  13. Isotopic fractionation of argon during stepwise release from shungite

    Science.gov (United States)

    Rison, W.

    1980-05-01

    It is noted that in previous attempts to determine the Ar-40/Ar-36 ratio in the ancient atmosphere, the only direct measurement yielding a value below the atmospheric value of today is for argon released at low temperatures from a pre-Cambrian shungite. In the present work, a low value for Ar-40/Ar-36 in gas released from a type I shungite at low temperatures is confirmed. Attention is given to a study of the accompanying Ar-38/Ar-36 ratios and the enhanced ratio of Ar-40/Ar-36 for the fractions released at high temperatures which shows that the effect observed is a result of the stepwise heating and the argon diffusion mobilized thereby. It is suggested that the low Ar-40/Ar-36 obtained in the past is from the same source rather than reflecting the isotropic composition of the pre-Cambrian atmosphere, and that the type I shungite may exhibit simple volume diffusion over macroscopic dimensions as glasses do. It is concluded that if this is so, the diffusion parameters obtained from the data would imply rapid exchange with the atmosphere for any argon initially trapped in the veins of the material.

  14. Tin LPP plasma control in the argon cusp source

    Science.gov (United States)

    McGeoch, Malcolm W.

    2016-03-01

    The argon cusp plasma has been introduced [1,2] for 500W class tin LPP exhaust control in view of its high power handling, predicted low tin back-scatter from a beam dump, and avoidance of hydrogen usage. The physics of tin ion control by a plasma is first discussed. Experimentally, cusp stability and exhaust disc geometry have previously been proved at full scale [2], the equivalent of 300W-500W usable EUV. Here we verify operation of the plasma barrier that maintains a high argon density next to the collector, for its protection, and a low density in the long path toward the intermediate focus, for efficiency. A pressure differential of 2Pa has been demonstrated in initial work. Other aspects of tin LPP plasma control by the cusp have now been demonstrated using tin ions from a low Hz 130mJ CO2 laser pulse onto a solid tin surface at the cusp center. Plasma is rejected at the design to match a specified exhaust power is discussed. In view of this work, argon cusp exhaust control appears to be very promising for 500W class tin LPP sources.

  15. Bacteria Inactivation Using DBD Plasma Jet in Atmospheric Pressure Argon

    Institute of Scientific and Technical Information of China (English)

    XU Guimin; ZHANG Guanjun; SHI Xingmin; MA Yue; WANG Ning; LI Yuan

    2009-01-01

    A coaxial dielectric barrier discharge plasma jet Was designed,which can be operated in atmospheric pressure argon under an intermediate frequency sinusoidal resonant power supply,and an atmospheric pressure glow-like discharge Was achieved.Two kinds of typical bacteria,i.e.,the Staphylococcus aureus(S.aurens)and Escherichia coil(E.coil),were employed to study the bacterial inactivation mechanism by means of the non-thermal plasma.The killing log value (KLV)of S.aureus reached up to 5.38 with a treatment time of 90 s and that of E.coil up to 5.36 with 60 s,respectively.According to the argon emission spectra of the plasma jet and the scanning electron microscope (SEM) images of the two bacteria before and after the plasma treatment.it is concluded that the reactive species in the argon plasma played a major role in the bacterial inactivation,while the heat,electric field and UV photons had little effect.

  16. Metal clusters on supported argon layers; Metallcluster auf dielektrischen Substraten

    Energy Technology Data Exchange (ETDEWEB)

    Faber, Bernhard

    2011-10-21

    The deposition of small sodium clusters on supported Ar(001)-surfaces is simulated. Theoretical description is achieved by a hierarchical model consisting of time-dependent DFT and molecular dynamics. The valence electrons of the sodium atoms are considered by Kohn-Sham-Scheme with self interaction correction. The interaction of argon atoms and sodium ions is described by atom-atom potentials whereas the coupling to the QM electrons is done by local pseudo-potentials. A decisive part of the model is the dynamical polarizability of the rare-gas atoms. The optional metal support is considered by the method of image charges. The influence of the forces caused by image charges and the influence of the number of argon monolayers on structure, optical response and deposition dynamics of Na{sub 6} and Na{sub 8} is investigated. There is very little influence on cluster structure and only a small shift of the cluster perpendicular to the surface. Concerning optical response the position of the Mie plasmon peak stays robust whereas the details of spectral fragmentation react very sensitively to changes. The forces caused by image charges of the metal support play only a little role with the dynamics of deposition while the thickness of the argon surface strongly influences the dissipation. (orig.)

  17. The formation and characteristics of hydride blisters in c.w. Zircaloy-2 pressure tubes

    International Nuclear Information System (INIS)

    Under the auspices of the IAEA, a consultants' meeting was arranged in Vienna, 1994 July 25-29, at which a Canadian delegation, consisting of AECL and Ontario Hydro Technologies personnel, presented information on their knowledge of the behaviour of hydride blisters in Zircaloy-2 pressure tubes. This document contains the 10 papers presented by the Canadian delegation to the meeting. It is believed that they represent a good reference document on hydride blister phenomena

  18. Direct hydride derivatization of methyl- and ethylmercury chlorides in aqueous solution with KBH4

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A convenient hydride derivatization procedure of methyl-and ethylmercury chlorides to volatile hydrides was reported. In sealed vials methylmercury and ethylmercury compounds in acidic aqueous solutions were converted into their volatile forms by the reaction with potassium tetrahydroborate(KBH4) and elvolved to the headspace of the vials. The gaseous analytes in the headspace were extracted and concentrated by solid phase microextraction(SPME) and injected into gas chromatography (GC) for separation and identified by mass selective detector(MS).

  19. Dehydrogenation in lithium borohydride/conventional metal hydride composite based on a mutual catalysis

    DEFF Research Database (Denmark)

    Yu, X.B.; Shi, Qing; Vegge, Tejs;

    2009-01-01

    The dehydrogenation of LiBH4 ball-milled with hydrogenated 40Ti–15Mn–15Cr–30V alloy was investigated. It was found that there is a mutual catalysis between the two hydrides, lowering the temperature of hydrogen release from both hydrides. In the case of 1h milled LiBH4/40Ti–15Mn–15Cr–30V with a...

  20. The thermodynamics of hydride precipitation: the importance of entropy, enthalpy and disorder

    OpenAIRE

    Lumley, S. C.; Grimes, R. W.; Murphy, S. T.; Burr, P. A.; Chroneos, A.; Chard-Tucke, P. R.; Wenman, M. R.

    2014-01-01

    The thermodynamics of H/{\\alpha}-Zr solid solution and zirconium hydride phases were studied using density functional theory. Disorder in {\\zeta}, {\\gamma} and {\\delta} hydrides and solid solutions were modelled using a statistically significant number of randomly generated structures in combination with special quasi-random structures and solid solutions with a range of concentrations. This is used in conjunction with a calculation of thermodynamic parameters of the system, including the tem...

  1. K-Ar age of young volcanic rocks and excess argon--Binary mixing model and quantitative study of excess argon effect

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A binary mixing model for excess argon is suggested in the note. According to this model and the data of excess argon component obtained in our experiment , a quantitative study of the effect of excess argon on real K-Ar age of young volcanic rocks is done. The result indicates that the effect of 5% excess argon component in samples on K-Ar age of the samples more than 2 Ma is less than 7.36% and can lead K-Ar age of 0.5 Ma samples to increase by 32.4%, while 1% excess argon component leads K-Ar age of 0.5 Ma samples to increase by 6.26%. Therefore, when pre-processed excess argon component is ≤1%, K-Ar age of the samples more than 0.5 Ma should be credible. On this basis we suggest a principal opinion for evaluation of previous K-Ar dating results and propose that the matrix is used to determine K-Ar age of young volcanic rocks. For the samples less than 0.2 Ma, in the case of high excess argon content, even if only 1% excess argon component exists in their matrix, it can also greatly affect their K-A age. Thus it must be careful to treat the dating result.

  2. On the chemistry of hydrides of N atoms and O$^+$ ions

    CERN Document Server

    Awad, Zainab; Williams, David A

    2016-01-01

    Previous work by various authors has suggested that the detection by Herschel/HIFI of nitrogen hydrides along the low density lines of sight towards G10.6-0.4 (W31C) cannot be accounted for by gas-phase chemical models. In this paper we investigate the role of surface reactions on dust grains in diffuse regions, and we find that formation of the hydrides by surface reactions on dust grains with efficiency comparable to that for H$_2$ formation reconciles models with observations of nitrogen hydrides. However, similar surface reactions do not contribute significantly to the hydrides of O$^+$ ions detected by Herschel/HIFI present along many sight lines in the Galaxy. The O$^+$ hydrides can be accounted for by conventional gas-phase chemistry either in diffuse clouds of very low density with normal cosmic ray fluxes or in somewhat denser diffuse clouds with high cosmic ray fluxes. Hydride chemistry in dense dark clouds appears to be dominated by gas-phase ion-molecule reactions.

  3. First-principles calculations of niobium hydride formation in superconducting radio-frequency cavities

    Energy Technology Data Exchange (ETDEWEB)

    Ford, Denise C.; Cooley, Lance D.; Seidman, David N.

    2013-09-01

    Niobium hydride is suspected to be a major contributor to degradation of the quality factor of niobium superconducting radio-frequency (SRF) cavities. In this study, we connect the fundamental properties of hydrogen in niobium to SRF cavity performance and processing. We modeled several of the niobium hydride phases relevant to SRF cavities and present their thermodynamic, electronic, and geometric properties determined from calculations based on density-functional theory. We find that the absorption of hydrogen from the gas phase into niobium is exothermic and hydrogen becomes somewhat anionic. The absorption of hydrogen by niobium lattice vacancies is strongly preferred over absorption into interstitial sites. A single vacancy can accommodate six hydrogen atoms in the symmetrically equivalent lowest-energy sites and additional hydrogen in the nearby interstitial sites affected by the strain field: this indicates that a vacancy can serve as a nucleation center for hydride phase formation. Small hydride precipitates may then occur near lattice vacancies upon cooling. Vacancy clusters and extended defects should also be enriched in hydrogen, potentially resulting in extended hydride phase regions upon cooling. We also assess the phase changes in the niobium-hydrogen system based on charge transfer between niobium and hydrogen, the strain field associated with interstitial hydrogen, and the geometry of the hydride phases. The results of this study stress the importance of not only the hydrogen content in niobium, but also the recovery state of niobium for the performance of SRF cavities.

  4. Investigation of Lithium Metal Hydride Materials for Mitigation of Deep Space Radiation

    Science.gov (United States)

    Rojdev, Kristina; Atwell, William

    2016-01-01

    Radiation exposure to crew, electronics, and non-metallic materials is one of many concerns with long-term, deep space travel. Mitigating this exposure is approached via a multi-faceted methodology focusing on multi-functional materials, vehicle configuration, and operational or mission constraints. In this set of research, we are focusing on new multi-functional materials that may have advantages over traditional shielding materials, such as polyethylene. Metal hydride materials are of particular interest for deep space radiation shielding due to their ability to store hydrogen, a low-Z material known to be an excellent radiation mitigator and a potential fuel source. We have previously investigated 41 different metal hydrides for their radiation mitigation potential. Of these metal hydrides, we found a set of lithium hydrides to be of particular interest due to their excellent shielding of galactic cosmic radiation. Given these results, we will continue our investigation of lithium hydrides by expanding our data set to include dose equivalent and to further understand why these materials outperformed polyethylene in a heavy ion environment. For this study, we used HZETRN 2010, a one-dimensional transport code developed by NASA Langley Research Center, to simulate radiation transport through the lithium hydrides. We focused on the 1977 solar minimum Galactic Cosmic Radiation environment and thicknesses of 1, 5, 10, 20, 30, 50, and 100 g/cm2 to stay consistent with our previous studies. The details of this work and the subsequent results will be discussed in this paper.

  5. Influence of lanthanon hydride catalysts on hydrogen storage properties of sodium alanates

    Institute of Scientific and Technical Information of China (English)

    WU Zhe; CHEN Lixin; XIAO Xuezhang; FAN Xiulin; LI Shouquan; WANG Qidong

    2013-01-01

    NaAlH4 complex hydrides doped with lanthanon hydrides were prepared by hydrogenation of the ball-milled NaH/Al+xmol.% RE-H composites (RE=La,Ce; x=2,4,6) using NaHl and A1 powder as raw materials.The influence of lanthanon hydride catalysts on the hydriding and dehydriding behaviors of the as-synthesized composites were investigated.It was found that the composite doped with 2 mol.% La.H3.01 displayed the highest hydrogen absorption capacity of 4.78 wt.% and desorption capacity of 4.66wt.%,respectively.Moreover,the composite doped with 6 mol% CeH2.51 showed the best hydriding/dehydriding reaction kinetics.The proposed catalytic mechanism for reversible hydrogen storage properties of the composite was attributed to the presence of active LaH3.01 and CeH2.51 particles,which were scattering on the surface of NaH and A1 particles,acting as the catalytic active sites for hydrogen diffusion and playing an important catalytic role in the improved hydriding/dehydriding reaction.

  6. Fracture mechanism of TiAl intermetallics caused by hydride and atomic hydrogen

    Institute of Scientific and Technical Information of China (English)

    高克玮; 王燕斌; 林志; 乔利杰; 褚武扬

    1999-01-01

    Hydrogen embrittlement (HE) of TiAl intermetallics was studied at room temperature. The results showed that there were two forms of HE in TiAl intermetallics, i.e. hydride HE and atomic HE. Most of hydrogen in TiAl intermetallics was transformed into hydrides at room temperature. The hydride exists as (TiAl)Hx for a low hydrogen concentration while it exists in several forms for a higher hydrogen concentration. Stress intensity factor KIC decreased with increase in hydride concentration. KIC decreased further when TiAl intermetallics were charged cathodically with hydrogen in 1 mol/L H2SO4 solution. Stress intensity factor during hydrogen charging KIH was about 50% KIC. 20% of the decrease was caused by hydrides while 30% was caused by atomic hydrogen. Mechanism of HE caused hydrides was the same as any other second phase in nature. Delayed fracture caused by atomic hydrogen resulted from hydrogen induced local plastic deformation.

  7. Roles of argon seeding in energy confinement and pedestal structure in JT-60U

    International Nuclear Information System (INIS)

    The mechanism of improving energy confinement with argon seeding at high density has been investigated in JT-60U. Better confinement is sustained at high density by argon seeding accompanied by higher core and pedestal temperatures. The electron density profiles become flatter with increasing density in conventional H-mode plasmas, whereas peaked density profiles are maintained with argon seeding. Density peaking and dilution effects lower the pedestal density at a given averaged density. The pedestal density in the argon seeded plasmas, which is lower than that in plasmas with deuterium puff, enables the pedestal temperature to be higher, whereas the increase in the pedestal pressure with argon seeding is small. High pedestal temperature is a boundary condition for high core temperature through profile stiffness, which leads to better confinement with argon seeding. The density peaking is a key factor of sustaining better confinement in argon seeded H-mode plasmas. The radiative loss power density is predominantly enhanced in the edge region by argon puff. The role of argon seeding in the pedestal characteristics has also been examined. The pedestal width becomes larger continuously with edge collisionality, but is nearly independent of the presence of argon seeding. (paper)

  8. Argon-41 production and evolution at the Oregon State University TRIGA Reactor (OSTR)

    International Nuclear Information System (INIS)

    In this study, argon-41 concentrations were measured at various locations within the reactor facility to assess the accuracy of models used to predict argon-41 evolution from the reactor tank, and to determine the relationship between argon gas evolution from the tank and subsequent argon-41 concentrations throughout the reactor room. In particular, argon-41 was measured directly above the reactor tank with the reactor tank lids closed, at other accessible locations on the reactor top with the tank lids both closed and open, and at several locations on the first floor of the reactor room. These measured concentrations were then compared to values calculated using a modified argon-41 production and evolution model for TRIGA reactor tanks and ventilation values applicable to the OSTR facility. The modified model was based in part on earlier TRIGA models for argon-41 production and release, but added features which improved the agreement between predicted and measured values. The approximate dose equivalent rate due to the presence of argon-41 in reactor room air was calculated for several different locations inside the OSTR facility. These dose rates were determined using the argon-41 concentration measured at each specific location, and were subsequently converted to a predicted quarterly dose equivalent for each location based on the reactor's operating history. The predicted quarterly dose equivalent values were then compared to quarterly doses measured by film badges deployed as dose-integrating area radiation monitors at the locations of interest. The results indicate that the modified production and evolution model is able to predict argon-41 concentrations to within a factor of ten when compared to the measured data. Quarterly dose equivalents calculated from the measured argon-41 concentrations and the reactor's operating history seemed consistent with results obtained from the integrating area radiation monitors. Given the argon-41 concentrations measured

  9. Complex Hydride Compounds with Enhanced Hydrogen Storage Capacity

    Energy Technology Data Exchange (ETDEWEB)

    Mosher, Daniel A.; Opalka, Susanne M.; Tang, Xia; Laube, Bruce L.; Brown, Ronald J.; Vanderspurt, Thomas H.; Arsenault, Sarah; Wu, Robert; Strickler, Jamie; Anton, Donald L.; Zidan, Ragaiy; Berseth, Polly

    2008-02-18

    The United Technologies Research Center (UTRC), in collaboration with major partners Albemarle Corporation (Albemarle) and the Savannah River National Laboratory (SRNL), conducted research to discover new hydride materials for the storage of hydrogen having on-board reversibility and a target gravimetric capacity of ≥ 7.5 weight percent (wt %). When integrated into a system with a reasonable efficiency of 60% (mass of hydride / total mass), this target material would produce a system gravimetric capacity of ≥ 4.5 wt %, consistent with the DOE 2007 target. The approach established for the project combined first principles modeling (FPM - UTRC) with multiple synthesis methods: Solid State Processing (SSP - UTRC), Solution Based Processing (SBP - Albemarle) and Molten State Processing (MSP - SRNL). In the search for novel compounds, each of these methods has advantages and disadvantages; by combining them, the potential for success was increased. During the project, UTRC refined its FPM framework which includes ground state (0 Kelvin) structural determinations, elevated temperature thermodynamic predictions and thermodynamic / phase diagram calculations. This modeling was used both to precede synthesis in a virtual search for new compounds and after initial synthesis to examine reaction details and options for modifications including co-reactant additions. The SSP synthesis method involved high energy ball milling which was simple, efficient for small batches and has proven effective for other storage material compositions. The SBP method produced very homogeneous chemical reactions, some of which cannot be performed via solid state routes, and would be the preferred approach for large scale production. The MSP technique is similar to the SSP method, but involves higher temperature and hydrogen pressure conditions to achieve greater species mobility. During the initial phases of the project, the focus was on higher order alanate complexes in the phase space

  10. Development of delayed hydride cracking resistant-pressure tube

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Suk; Kwon, Sang Chul; Kim, S. S.; Yim, K. S

    2000-10-01

    For the first time, we demonstrate that the pattern of nucleation and growth of a DHC crack is governed by the precipitation of hydrides so that the DHC velocity and K{sub IH} are determined by an angle of the cracking plane and the hydride habit plane 10.7. Since texture controls the distribution of the 10.7 habit plane in Zr-2.5Nb pressure tube, we draw a conclusion that a textural change in Zr-2.5Nb tube from a strong tangential texture to the radial texture shall increase the threshold stress intensity factor, K{sub IH}, and decrease the delayed hydride cracking velocity. This conclusion is also verified by a complimentary experiment showing a linear dependence of DHCV and K{sub IH} with an increase in the basal component in the cracking plane. On the basis of the study on the DHC mechanism and the effect of manufacturing processes on the properties of Zr-2.5Nb tube, we have established a manufacturing procedure to make pressure tubes with improved DHC resistance. The main features of the established manufacturing process consist in the two step-cold pilgering process and the intermediate heat treatment in the {alpha} + {beta} phase for Zr-2.5Nb alloy and in the {alpha} phase for Zr-1Nb-1.2Sn-0.4Fe alloy. The manufacturing of DHC resistant-pressure tubes of Zr-2.5Nb and Zr-1N-1.2Sn-0.4Fe was made in the ChMP zirconium plant in Russia under a joint research with Drs. Nikulina and Markelov in VNIINM (Russia). Zr-2.5Nb pressure tube made with the established manufacturing process has met all the specification requirements put by KAERI. Chracterization tests have been jointly conducted by VNIINM and KAERI. As expected, the Zr-2.5Nb tube made with the established procedure has improved DHC resistance compared to that of CANDU Zr-2.5Nb pressure tube used currently. The measured DHC velocity of the Zr-2.5Nb tube meets the target value (DHCV <5x10{sup -8} m/s) and its other properties also were equivalent to those of the CANDU Zr-2.5Nb tube used currently. The Zr-1Nb-1

  11. The effects of argon in the bioenergetics of the hamster and the rat

    Science.gov (United States)

    Tempel, G. E.; Musacchia, X. J.

    1974-01-01

    Oxygen consumption was examined in hamsters and rats exposed to normoxic mixtures of argon at 1 atm. In fasted and nonfasted animals, no marked change in O2 utilization was detectable at 22 C. However, at 7 C a significant decrease in oxygen consumption was observed where the animals were exposed in argon. The data are interpreted in terms of the greater thermal conductivity of nitrogen. The study was prompted by conflicting reports on the metabolic effects of argon and helium.

  12. Argon Laser Photoablation for Treating Benign Pigmented Conjunctival Nevi

    Science.gov (United States)

    Alsharif, Abdulrahman M.; Al-Gehedan, Saeed M.; Alasbali, Tariq; Alkuraya, Hisham S.; Lotfy, Nancy M.; Khandekar, Rajiv

    2016-01-01

    Purpose: To evaluate the outcomes of argon laser photoablation of benign conjunctival pigmented nevi with different clinical presentations. Patients and Methods: This interventional case series was conducted between July 2014 and January 2015. Patients presenting with benign conjunctival nevi were included. Data were collected on the clinical features at presentation, argon laser photoablation, and follow-up at 8 and 24 weeks. Postoperative photography allowed recording of the success of each case and the overall success rate. Complete removal of conjunctival pigments was considered an absolute success. Partial pigmentation requiring repeat laser treatment was considered a qualified success. Results: There were 14 eyes (four right eyes and ten left eyes) with benign pigmented conjunctival nevi. There were three males and eight females in the study sample. The median age was 36 (25% percentile: 26 years). Three patients had bilateral lesions. The nevi were located temporally in nine eyes, nasally in three eyes, and on the inferior bulbar conjunctiva in two eyes. The mean horizontal and vertical diameters of nevi were 5 ± 2 mm and 4 ± 2.7 mm, respectively. The mean follow-up period was 5 months. Following laser treatment, no eyes had subconjunctival hemorrhage, infection, scarring, neovascularization, recurrence, or corneal damage. The absolute success rate of laser ablation was 79%. Three eyes with elevated nevi had one to three sessions of laser ablation resulting in a qualified success rate of 100%. Conclusions: Argon laser ablation was a safe and effective treatment for the treatment of selective benign pigmented conjunctival nevi in Arab patients. PMID:27555708

  13. The abundances of neon, sulfur, and argon in planetary nebulae

    Science.gov (United States)

    Beck, S. C.; Lacy, J. H.; Townes, C. H.; Aller, L. H.; Geballe, T. R.; Baas, F.

    1981-01-01

    New infrared observations of Ne II, Ar III, and S IV are used in optical observations of other ionization states of the considered elements to evaluate the abundances of neon, argon, and sulfur in 18 planetary nebulae. Attention is also given to one or more of the infrared lines in 18 other nebulae. It is pointed out that S IV was detected in approximately 90% of the observed objects, while Ar III was found in about 80%, and Ne II in roughly one-third. It is noted that optical observations typically include only a limited region of the nebula, while the infrared measurements frequently involve integration over the entire nebular image.

  14. Ionization coefficients for argon in a micro-discharge

    International Nuclear Information System (INIS)

    Ionization coefficients are measured for electrons in a dc micro-discharge in argon from optical emission profiles. The micro-discharge is operated in the Townsend regime between two parallel-plate electrodes. Axial profiles of emission are obtained with sufficient resolution to provide spatial ionization coefficients. The measured coefficients agree very well with the data obtained from other sources, indicating the operation of the discharge in the Townsend regime and also that Townsend mechanisms do not need extension to describe such discharges. (paper)

  15. Kinetic modeling of the Townsend breakdown in argon

    Science.gov (United States)

    Macheret, S. O.; Shneider, M. N.

    2013-10-01

    Kinetic modeling of the Townsend breakdown in argon was performed in the "forward-back" approximation. The kinetic model was found to adequately describe the left branch of the Paschen curve, and the important role of ionization by fast ions and atoms near the cathode, as well as the increase in secondary emission coefficient in strong electric fields described in the literature, was confirmed. The modeling also showed that the electron energy distribution function develops a beam of high-energy electrons and that the runaway effect, i.e., the monotonic increase of the mean electron energy with the distance from the cathode, occurs at the left branch of the Paschen curve.

  16. Ionization coefficients for argon in a micro-discharge

    Science.gov (United States)

    Kuschel, Thomas; Stefanović, Ilija; Malović, Gordana; Marić, Dragana; Petrović, Zoran Lj

    2013-08-01

    Ionization coefficients are measured for electrons in a dc micro-discharge in argon from optical emission profiles. The micro-discharge is operated in the Townsend regime between two parallel-plate electrodes. Axial profiles of emission are obtained with sufficient resolution to provide spatial ionization coefficients. The measured coefficients agree very well with the data obtained from other sources, indicating the operation of the discharge in the Townsend regime and also that Townsend mechanisms do not need extension to describe such discharges.

  17. Diffusion coefficient of metal vapours into rare gases. Mercury - argon

    International Nuclear Information System (INIS)

    The source information is present as well as the results of analysis and integration of data on mutual diffusion coefficient (MDC) of mercury - argon mixture at Hg concentration → 0 in 300-2500 K temperature range. Reference data on MDC for metal - inert gas binary mixtures obtained on the base of complex analysis of various information, as it exemplified by Hg-Ar pair, can be used as a part of metrological support at calibration of devices for determination MDC of gas - metal vapors

  18. Electron drift velocity in argon-methane mixture

    International Nuclear Information System (INIS)

    Described are the results of a series of measurements of electron drift velocity taken with samples of chemically pure grade gas mixture of Ar-10% CH4 (N2222O<2 ppm). The measured drift velocity is plotted as a function of the ratio of electric field to pressure in the range from 0.05 to 0.8 V/cmxtorr. The measurements are reproducible only to within 4%. The results of numerical calculations employing the well-established argon elastic and methane elastic and inelastic cross sections are also included. The disagreement from the present experimental results, and from those obtained elsewhere, is rather puzzling

  19. High intensity, argon ion laser-jet photochemistry

    Science.gov (United States)

    Wilson, R. Marshall; Schnapp, Karlyn A.; Hannemann, Klaus; Ho, Douglas M.; Memarian, Hamid R.; Azadnia, Ardeshir; Pinhas, Allan R.; Figley, Timothy M.

    A new technique for the study of high intensity solution photochemistry has been developed. With this laser-jet technique, a high velocity microjet is irradiated with the focussed output of an argon ion laser. Under these extremely high intensity conditions, photochemically generated transient species with suitable absorption properties are excited further and produce relatively large amounts of photoproducts which are not observed under low intensity conditions. The application of this laser-jet technique in the study of the photochemistry of radicals, biradicals, photoenols and the higher excited states of carbonyl and polycyclic aromatic compounds is described.

  20. Optical fiber read-out for liquid argon scintillation light

    CERN Document Server

    Csáthy, J Janicskó; Kratz, J; Schönert, S; Wiesinger, Ch

    2016-01-01

    In this paper we describe the performance of a light detector for Ar scintillation light made of wavelength-shifting (WLS) fibers connected to Silicon-Photomultipliers (SiPM). The setup was conceived to be used as anti-Compton veto for high purity germanium (HPGe) detectors operated directly in liquid Argon (LAr). Background suppression efficiencies for different radioactive sources were measured in a test cryostat with about 800 kg LAr. This work was part of the R\\&D effort for the GERDA experiment.

  1. Study of a novel electromagnetic liquid argon calorimeter TGT

    International Nuclear Information System (INIS)

    The concept and the basic design of a fast, highly granular and compact electromagnetic liquid argon calorimeter are described. This novel calorimeter offers uniform energy response and constant energy resolution independent of the production angle of an impinging particle and of its impact position at the calorimeter. An example of a calorimeter with full rapidity coverage in an application in a collider detector is given. An important aspect of the concept is the electronics for fast signal processing matched to the short charge collection time. We report on the experience with the realization of a prototype calorimeter module and on its performance in a test beam exposure. 15 refs., 16 figs., 2 tabs

  2. Activation of copper by nitrogen and argon beams

    Energy Technology Data Exchange (ETDEWEB)

    Chetvertkova, Vera [IAP, Goethe-University, Frankfurt am Main (Germany); GSI Darmstadt (Germany); Mustafin, Edil; Strasik, Ivan [GSI Darmstadt (Germany); Belousov, Anton [TU Darmstadt (Germany); Latysheva, Ludmila; Sobolevsky, Nikolai [INR RAS, Moscow (Russian Federation); Ratzinger, Ulrich [IAP, Goethe-University, Frankfurt am Main (Germany)

    2012-07-01

    Monte Carlo transport codes are widely used for various purposes in nuclear physics, radiation protection, medical applications, accelerator design etc. Code verification by experiments is needed to be sure that the codes give accurate results. New data on the activation of copper by a nitrogen beam of 500 MeV/u is presented and compared with FLUKA and SHIELD simulation results. The activation of copper by a nitrogen beam is compared to activation by an argon beam and respective simulations. This gives a chance to see the accuracy of the codes at different projectile masses. Correspondences and discrepancies of calculations and experiments are discussed.

  3. Study of a Novel Concept for a Liquid Argon Calorimeter \

    CERN Multimedia

    2002-01-01

    % RD33 \\\\ \\\\ The development of a fast, highly granular and compact electromagnetic liquid argon calorimeter prototype is proposed as a generic R\\&D project for a novel concept of calorimetry in proton-proton and electron-positron collider detectors: the $^{\\prime$Thin Gap Turbine$^{\\prime}$ (TGT). The TGT calorimeter has a modular construction, is flexible in its longitudinal and transverse granularity, and offers a uniform energy response and resolution, independent of the production angle of incident particles. An important aspect of the project is the development of fast, radiation-hard front-end electronics which is operating in the cold.

  4. Activation of aluminum by argon: Experimental study and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Chetvertkova, V., E-mail: v.chetvertkova@gsi.de [GSI Helmholtzzentrum fuer Schwerionenforschung Darmstadt, Planckstrasse 1, 64291 Darmstadt (Germany); J. W. Goethe-University Frankfurt am Main, IAP, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Strasik, I. [GSI Helmholtzzentrum fuer Schwerionenforschung Darmstadt, Planckstrasse 1, 64291 Darmstadt (Germany); J. W. Goethe-University Frankfurt am Main, IAP, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Belousov, A. [GSI Helmholtzzentrum fuer Schwerionenforschung Darmstadt, Planckstrasse 1, 64291 Darmstadt (Germany); Iwase, H. [High Energy Accelerator Research Organization, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Mokhov, N. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Mustafin, E. [GSI Helmholtzzentrum fuer Schwerionenforschung Darmstadt, Planckstrasse 1, 64291 Darmstadt (Germany); Latysheva, L. [Institute for Nuclear Research RAS, 117312 Moscow (Russian Federation); Pavlovic, M. [FEI STU, Ilkovicova 3, 812 19 Bratislava (Slovakia); Ratzinger, U. [J. W. Goethe-University Frankfurt am Main, IAP, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Sobolevsky, N. [Institute for Nuclear Research RAS, 117312 Moscow (Russian Federation)

    2011-06-15

    The paper presents the results of irradiation of aluminum targets by 430 and 500 MeV/u argon beams. Gamma-spectra were measured after the end of the irradiation in order to identify the induced nuclides as well as to determine their residual activity depth-profiles. The results of this experiment are compared with Monte Carlo simulations by FLUKA, GEANT4, MARS, PHITS and SHIELD-A codes. In case of a thin target, the agreement between the experiment and simulations is satisfactory, while in case of a thick target, some discrepancies are observed.

  5. Laser-induced vibrational dynamics of ozone in solid argon

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Amstrup, B.; Henriksen, Niels Engholm

    1997-01-01

    We consider the vibrational dynamics, induced by an intense infrared laser pulse, in an ozone molecule with isotopic substitution, that is, (OOO)-O-16-O-16-O-18 and compare the dynamics in the gas phase and in solid ar on. not perturbed by argon on a time-scale of a few picoseconds and selective...... bond-breaking in the molecule should be possible following the same laser control scheme as suggested in the gas phase. (C) 1997 Elsevier Science B.V....

  6. Electron transport in argon in crossed electric and magnetic fields

    Science.gov (United States)

    Ness; Makabe

    2000-09-01

    An investigation of electron transport in argon in the presence of crossed electric and magnetic fields is carried out over a wide range of values of electric and magnetic field strengths. Values of mean energy, ionization rate, drift velocity, and diffusion tensor are reported here. Two unexpected phenomena arise; for certain values of electric and magnetic field we find regions where the swarm mean energy decreases with increasing electric fields for a fixed magnetic field and regions where swarm mean energy increases with increasing magnetic field for a fixed electric field. PMID:11088933

  7. Influence of hydrides orientation on strain, damage and failure of hydrided zircaloy-4; Influence de l'orientation des hydrures sur les modes de deformation, d'endommagement et de rupture du zircaloy-4 hydrure

    Energy Technology Data Exchange (ETDEWEB)

    Racine, A

    2005-09-15

    In pressurized water reactors of nuclear power plants, fuel pellets are contained in cladding tubes, made of Zirconium alloy, for instance Zircaloy-4. During their life in the primary water of the reactor (155 bars, 300 C), cladding tubes are oxidized and consequently hydrided. A part of the hydrogen given off precipitates as Zirconium hydrides in the bulk material and embrittles the material. This embrittlement depends on many parameters, among which hydrogen content and orientation of hydrides with respect to the applied stress. This investigation is devoted to the influence of the orientation of hydrides with respect to the applied stress on strain, damage and failure mechanisms. Macroscopic and SEM in-situ ring tensile tests are performed on cladding tube material (unirradiated cold worked stress-relieved Zircaloy-4) hydrided with about 200 and 500 wppm hydrogen, and with different main hydrides orientation: either parallel or perpendicular to the circumferential tensile direction. We get the mechanical response of the material as a function of hydride orientation and hydrogen content and we investigate the deformation, damage and failure mechanisms. In both cases, digital image correlation techniques are used to estimate local and global strain distributions. Neither the tensile stress-strain response nor the global and local strain modes are significantly affected by hydrogen content or hydride orientation, but the failure modes are strongly modified. Indeed, only 200 wppm radial hydrides embrittle Zy-4: sample fail in the elastic domain at about 350 MPa before strain bands could develop; whereas in other cases sample reach at least 750 MPa before necking and final failure, in ductile or brittle mode. To model this particular heterogeneous material behavior, a non-coupled damage approach which takes into account the anisotropic distribution of the hydrides is proposed. Its parameters are identified from the macroscopic strain field measurements and a

  8. Improved Electrochemical Performance of Surface-Modified Metal Hydride Electrodes

    Institute of Scientific and Technical Information of China (English)

    YANG Kai; WU Feng; CHEN Shi; ZHANG Cun-zhong

    2005-01-01

    A novel plating process was applied to the surface modification of the metal hydride (MH) electrode of the MH/Ni batteries. The electrode was plated with a thin nickel film about 0.1 μm thick by using multi-arc ion plating technique. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used to analyze the electrodes. Influence of the surface modification on the performance of the MH/Ni batteries was studied. It is shown that the surface modification could enhance the electrode conductivity and decrease the batteries ohimic resistance by 28.2 %. After surface modification, the discharge capacity of modification also improves the cyclic durability of the batteries. The inner pressure of the batteries with modified electrode during overcharging is much lower than that with unmodified electrode. The experimental results demonstrate that this process is an effective way for the surface modification of the electrode of MH/Ni batteries.

  9. Superhalogens as Building Blocks of Complex Hydrides for Hydrogen Storage

    CERN Document Server

    Srivastava, Ambrish Kumar

    2016-01-01

    Superhalogens are species whose electron affinity (EA) or vertical detachment energy (VDE) exceed to those of halogen. These species typically consist of a central electropositive atom with electronegative ligands. The EA or VDE of species can be further increased by using superhalogen as ligands, which are termed as hyperhalogen. Having established BH4- as a superhalogen, we have studied BH4-x(BH4)x- (x = 1 to 4) hyperhalogen anions and their Li-complexes, LiBH4-x(BH4)x using density functional theory. The VDE of these anions is larger than that of BH4-, which increases with the increase in the number of peripheral BH4 moieties (x). The hydrogen storage capacity of LiBH4-x(BH4)x complexes is higher but binding energy is smaller than that of LiBH4, a typical complex hydride. The linear correlation between dehydrogenation energy of LiBH4-x(BH4)x complexes and VDE of BH4-x(BH4)x- anions is established. These complexes are found to be thermodynamically stable against dissociation into LiBH4 and borane. This stud...

  10. Unloading Effect on Delayed Hydride Cracking in Zirconium Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Suk; Kim, Sung Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-05-15

    It is well-known that a tensile overload retards not only the crack growth rate (CGR) in zirconium alloys during the delayed hydride cracking (DHC) tests but also the fatigue crack growth rate in metals, the cause of which is unclear to date. A considerable decrease in the fatigue crack growth rate due to overload is suggested to occur due either to the crack closure or to compressive stresses or strains arising from unloading of the overload. However, the role of the crack closure or the compressive stress in the crack growth rate remains yet to be understood because of incomplete understanding of crack growth kinetics. The aim of this study is to resolve the effect of unloading on the CGR of zirconium alloys, which comes in last among the unresolved issues as listed above. To this end, the CGRs of the Zr-2.5Nb tubes were determined at a constant temperature under the cyclic load with the load ratio, R changing from 0.13 to 0.66 where the extent of unloading became higher at the lower R. More direct evidence for the effect of unloading after an overload is provided using Simpson's experiment investigating the effect on the CGR of a Zr-2.5Nb tube of the stress states of the prefatigue crack tip by unloading or annealing after the formation of a pre-fatigue crack

  11. Synthesis and Hydrogen Desorption Properties of Aluminum Hydrides.

    Science.gov (United States)

    Jeong, Wanseop; Lee, Sang-Hwa; Kim, Jaeyong

    2016-03-01

    Aluminum hydride (AlH3 or alane) is known to store maximum 10.1 wt.% of hydrogen at relatively low temperature (hydrogen desorption are still not clear. To understand the desorption properties of hydrogen in alane, thermodynamically stable α-AlH3 was synthesized by employing an ethereal reaction method. The dependence of pathways on phase formation and the properties of hydrogen evolution were investigated, and the results were compared with the ones for γ-AlH3. It was found that γ-AlH3 requires 10 degrees C higher than that of γ-AlH3 to form, and its decomposition rate demonstrated enhanced endothermic stabilities. For desorption, all hydrogen atoms of alane evolved under an isothermal condition at 138 degrees C in less than 1 hour, and the sample completely transformed to pure aluminum. Our results show that the total amount of desorbed hydrogen from α-AlH3 exceeded 9.05 wt.%, with a possibility of further increase. Easy synthesis, thermal stability, and a large amount of hydrogen desorption of alane fulfill the requirements for light-weight hydrogen storage materials once the pathway of hydrogen cycling is provided.

  12. Another Look at the Mechanisms of Hydride Transfer Enzymes from Quantum and Classical Transition Path Sampling

    Science.gov (United States)

    Dzierlenga, Michael; Antoniou, Dimitri; Schwartz, Steven

    2015-03-01

    The mechanisms involved in enzymatic hydride transfer have been studies for years but questions remain, due to the difficulty in determining the participation of protein dynamics and quantum effects, especially hydrogen tunneling. In this study, we use transition path sampling (TPS) with normal mode centroid molecular dynamics (CMD) to calculate the barrier to hydride transfer in yeast alcohol dehydrogenase (YADH) and lactate dehydrogenase (LDH). Calculation of the work applied to the hydride during the reaction allows for observation of the change in barrier height due to inclusion of quantum effects. Additionally, the same calculations were performed using deuterium as the transferring particle to validate our methods with experimentally measured kinetic isotope effects. The change in barrier height in YADH upon inclusion of quantum effects is indicative of a zero-point energy contribution, and is evidence that the protein mediates a near-barrierless transfer of the rate-limiting hydride. Calculation of kinetic isotope effects using the average difference in barrier between hydride and deuteride agreed well with experimental results. The authors acknowledge the support of the National Institutes of Health Grants GM068036 and GM102226.

  13. Hydrogen transmission/storage with a metal hydride/organic slurry

    Energy Technology Data Exchange (ETDEWEB)

    Breault, R.W.; Rolfe, J.; McClaine, A. [Thermo Power Corp., Waltham, MA (United States)

    1998-08-01

    Thermo Power Corporation has developed a new approach for the production, transmission, and storage of hydrogen. In this approach, a chemical hydride slurry is used as the hydrogen carrier and storage media. The slurry protects the hydride from unanticipated contact with moisture in the air and makes the hydride pumpable. At the point of storage and use, a chemical hydride/water reaction is used to produce high-purity hydrogen. An essential feature of this approach is the recovery and recycle of the spent hydride at centralized processing plants, resulting in an overall low cost for hydrogen. This approach has two clear benefits: it greatly improves energy transmission and storage characteristics of hydrogen as a fuel, and it produces the hydrogen carrier efficiently and economically from a low cost carbon source. The preliminary economic analysis of the process indicates that hydrogen can be produced for $3.85 per million Btu based on a carbon cost of $1.42 per million Btu and a plant sized to serve a million cars per day. This compares to current costs of approximately $9.00 per million Btu to produce hydrogen from $3.00 per million Btu natural gas, and $25 per million Btu to produce hydrogen by electrolysis from $0.05 per Kwh electricity. The present standard for production of hydrogen from renewable energy is photovoltaic-electrolysis at $100 to $150 per million Btu.

  14. Cool-down induced hydride reorientation of hydrogen-charged Zirconium alloy cladding tubes

    International Nuclear Information System (INIS)

    250 and 500ppm hydrogen-charged Zirconium alloy tubes were employed to investigate hydride reorientation behaviors when they were cool down from 400 to 300, 200degC and room temperature with various cooling rates of 0.3, 2.0, 4.0, 7.0 and 15.0degC/min under a tensile hoop stress of 150MPa. These cool-down tests indicate that the slower cooling rate and the lower terminal cool-down temperature produced the more hydrides precipitated along with the larger fraction and the longer length of radial hydrides. These phenomena may be explained by terminal solid solubility of hydrogen for dissolution and precipitation and cooling rate-dependent hydride nucleation and growth rates. On the other hand, a dramatic decrease of ultimate tensile strength and plastic strain of the cool-down tested specimens may be explained by the amount of the radial hydrides precipitated during the cool-down process. (author)

  15. Hydrides blister formation and induced embrittlement on zircaloy-4 cladding tubes in reactivity initiated conditions

    International Nuclear Information System (INIS)

    Our aim is to study the cladding fracture with mechanical tests more representative of RIA conditions, taking into account the hydrides blisters, representative strain rates and stress states. To obtain hydride blisters, we developed a thermodiffusion setup that reproduces blister growth in reactor conditions. By metallography, nano-hardness, XRD and ERDA, we showed that they are constituted by 80% to 100% of δ hydrides in a Zircaloy-4 matrix, and that the zirconium beneath has some radially oriented hydrides. We modeled the blister growth kinetics taking into account the hysteresis of the hydrogen solubility limit and defined the thermal gradient threshold for blister growth. The modeling of the dilatometric behavior of hydrided zirconium indicates the important role of the material crystallographic texture, which could explain differences in the blister shape. Mechanical tests monitored with an infrared camera showed that significant local heating occurred at strain rates higher than 0.1/s. In parallel, the Expansion Due to Compression test was optimized to increase the bi-axiality level from uniaxial stress to plane strain (HB-EDC and VHB-EDC tests). This increase in loading bi-axiality lowers greatly the fracture strain at 25 C and 350 C only in homogeneous material without blister. Eventually, the ductility decrease of unirradiated Zircaloy-4 cladding tube in function of the blister depth was quantified. (author)

  16. LArIAT: Liquid Argon In A Testbeam

    CERN Document Server

    Cavanna, F; Raaf, J; Rebel, B

    2014-01-01

    Liquid Argon Time Projection Chambers (LArTPCs) are ideal detectors for precision neutrino physics. These detectors, when located deep underground, can also be used for measurements of proton decay, and astrophysical neutrinos. The technology must be completely developed, up to very large mass scales, and fully mastered to construct and operate these detectors for this physics program. As part of an integrated plan of developing these detectors, accurate measurements in LArTPC of known particle species in the relevant energy ranges are now deemed as necessary. The LArIAT program aims to directly achieve these goals by deploying LArTPC detectors in a dedicated calibration test beam line at Fermilab. The set of measurements envisaged here are significant for both the short-baseline (SBN) and long-baseline (LBN) neutrino oscillation programs in the US, starting with MicroBooNE in the near term and with the adjoint near and far liquid argon detectors in the Booster beam line at Fermilab envisioned in the mid-term...

  17. A liquid argon scintillation veto for the GERDA experiment

    International Nuclear Information System (INIS)

    Gerda is an experiment to search for the neutrinoless double beta decay of 76Ge. Results of Phase I have been published in summer 2013. Currently Gerda is being upgraded to a second phase. To reach the aspired background index of ≤ 10-3 cts/(keV . kg . yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). It has been demonstrated by the LArGe test facility that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. This talk focusses on the light instrumentation which is being installed in GERDA. Photomultiplier tubes (PMT) and wavelength-shifting fibers connected to silicon photomultipliers (SiPM) are combined to maximize the photoelectron-yield with respect to various background sources. Monte Carlo simulations have been performed to optimize the design for background suppression and low self-induced background. First results of the prototypes and the progress of installation are reported.

  18. A liquid argon scintillation veto for the GERDA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wegmann, Anne [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Collaboration: GERDA-Collaboration

    2014-07-01

    Gerda is an experiment to search for the neutrinoless double beta decay of {sup 76}Ge. Results of Phase I have been published in summer 2013. Currently Gerda is being upgraded to a second phase. To reach the aspired background index of ≤ 10{sup -3} cts/(keV . kg . yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). It has been demonstrated by the LArGe test facility that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. This talk focusses on the light instrumentation which is being installed in GERDA. Photomultiplier tubes (PMT) and wavelength-shifting fibers connected to silicon photomultipliers (SiPM) are combined to maximize the photoelectron-yield with respect to various background sources. Monte Carlo simulations have been performed to optimize the design for background suppression and low self-induced background. First results of the prototypes and the progress of installation are reported.

  19. Some transport properties in plasmas containing argon and fluorine

    Directory of Open Access Journals (Sweden)

    Novaković R.N.V.

    2003-01-01

    Full Text Available In this paper some results of numerical evaluation of transport coefficients in plasmas in the mixtures of argon and fluorine are presented. These transport characteristics are given in the function of the temperature for low pressures ranging from 0,1 kPa to 1,0 kPa and for low temperatures between 500 K and 5 000 K in argon plasmas with 20% and 30% of the fluorine added. It is assumed that the system is kept under constant pressure and that a corresponding state of local thermodynamical equilibrium (LTE is attained in it. The equilibrium plasma composition, necessary for the evaluations, was determined on the ground of the Saha equations for ionization processes and the law of mass action for the thermal dissociation of F2, combined with the charge conservation relation and the assumption that the pressure remained constant in the course of temperature variations. The ionization energy lowering, required in conjunction with the Saha equations, was obtained with the aid of a modified expression for the plasma Debye radius proposed previously. A previously derived expression for the modified Debye radius, offering the possibility to treat the plasmas considered as weakly non-ideal in the whole temperature range, is used. The cut-off at the Landau length rather than of the smallest of ionic radii is introduced. This alteration in the evaluation procedure brings different considerable changes in the final numerical results for the all relevant quantities.

  20. Compilation of electron collision excitation cross sections for neutro argon

    International Nuclear Information System (INIS)

    The present work presents a compilation and critical analysis of the available data on electron collision excitation cross sections for neutral Argon levels. This study includes: 1.- A detailed description in intermediate coupling for all the levels belonging the 20 configurations 3p''5 ns(n=4 to 12), np(n=4 to 8) and nd(n=3 to 8) of neutral Argon. 2.- Calculation of the electron collision excitation cross sections in Born and Born-Oppenheimer-Ochkur approximations for all the levels in the 14 configurations 3p''5 ns(n=4 to 7), np(n=4 to 7) and nd(n=3 to 8). 3.- Comparison and discussion of the compiled data. These are the experimental and theoretical values available from the literature, and those from this work. 4.- Analysis of the regularities and systematic behaviors in order to determine which values can be considered more reliable. It is show that the concept of one electron cross section results quite useful for this purpose. In some cases it has been possible to obtain in this way approximate analytical expressions interpolating the experimental data. 5.- All the experimental and theoretical values studied are graphically presented and compared. 6.- The last part of the work includes a listing of several general purpose programs for Atomic Physics calculations developed for this work. (Author)

  1. Elastic properties of liquid and solid argon in nanopores.

    Science.gov (United States)

    Schappert, Klaus; Pelster, Rolf

    2013-10-16

    We have measured sorption isotherms and determined the intrinsic longitudinal elastic modulus β(Ar,ads) of nanoconfined material via ultrasonic measurements combined with a special effective medium analysis. In the liquid regime the adsorbate only contributes to the measured effective properties when the pores are completely filled and the modulus is bulklike. At partial fillings its contribution is cancelled out by the high compressibility of the vapour phase. In contrast, at lower temperatures frozen argon as well as underlying liquid surface layers cause a linear increase of the effective longitudinal modulus upon filling. During sorption the contribution of the liquid surface layers near the pore wall β(Ar,surf) increases with the thickness of the solid layers reaching the bulk value β(Ar,liquid) only in the limit of complete pore filling. We interpret this effect as due to the gradual stiffening of the solid argon membrane. The measurements and their analysis show that longitudinal ultrasonic waves are well suited to the study of the elastic properties and liquid-solid phase transitions in porous systems. This method should also help to detect the influence of nanoconfinement on elastic properties in further research. PMID:24057946

  2. Local effects of ECRH on argon transport at ASDEX upgrade

    International Nuclear Information System (INIS)

    Future deuterium-tritium magnetically confined fusion power plants will most probably rely an high-Z Plasma Facing Components (PFCs) such as tungsten. This choice is determined by the necessity of low erosion of the first wall materials (to guarantee a long lifetime of the wall components) and by the need to avoid the too high tritium wall retention of typical carbon based PFCs. The experience gathered at the ASDEX Upgrade (AUG) tokamak has demonstrated the possibility of reliable and high performance plasma operation with a full tungsten-coated first wall. The observed accumulation of tungsten which can lead to excessive radiation losses is mitigated with the use of Electron Cyclotron Resonance Heating (ECRH). Although this impurity control method is routinely performed at AUG, the underlying physics principles are still not clear. This thesis aims an providing further knowledge an the effects of ECRH an the transport of impurities inside the core plasma. The transport of argon has been therefore investigated in-depth in purely ECR heated L-mode (low-confinement) discharges. Studies an impurity transport in centrally ECR heated nitrogen-seeded H-mode (high-confinement) discharges have also been performed. To this scope, a new crystal X-ray spectrometer of the Johann type has been installed an AUG for argon concentration and ion temperature measurements. New methods for the experimental determination of the total argon density through the integrated use of this diagnostic and of the Soft X-Ray (SXR) diode arrays have been developed. This gives the possibility of evaluating the full profiles of the argon transport coefficients from the linear flux-gradient dependency of local argon density. In comparison to classical χ2-minimization methods, the approach proposed here delivers transport coefficients intrinsically independent of the modelling of periodic relaxation mechanisms such as those Lied to sawtooth MHD (Magneto-Hydro-Dynamic) activity. Moreover, the good

  3. Tandem olefin metathesis/hydrogenation at ambient temperature: activation of ruthenium carbene complexes by addition of hydrides.

    Science.gov (United States)

    Schmidt, Bernd; Pohler, Michael

    2003-07-21

    Sodium hydride activates ruthenium carbene complexes to catalyze hydrogenation reactions subsequent to ring closing olefin metathesis. Under these conditions, hydrogenation of cyclopentenols proceeds smoothly at ambient temperature and under 1 atm of hydrogen in toluene. An alternative protocol was developed that involves the formation of hydrogen in situ by reaction of excess sodium hydride with protic functional groups and water. PMID:12956069

  4. Preparation of Uranium Powder having Reactive Shape using Uranium Hydridation

    International Nuclear Information System (INIS)

    The accident tolerance of the LWR fuel has become a primary matter of concern. So, it is indispensable to develop the innovative nuclear fuel material concepts and technologies which can overcome degradation of fuel safety and integrity. Uranium nitride fuel has been proposed as a potential fuel material for advanced nuclear reactors because nitride fuel has the advantages of both metallic and oxide fuels. That is, the high melting point, high uranium density, and high thermal conductivity are the representative merits of nitride fuel. Nitride fuel is also considered as a fuel material for the accident tolerant fuel of current LWRs to compensate for the decrease in fissile fuel material caused by adopting a thickened cladding such as SiC composites. However, nitride fuel has a critical disadvantage of a serious reaction with water at a typical LWR condition. Bulk uranium nitride is known to be dissolved in water at a temperature above 230 .deg. C. Uranium nitride powder is more unstable and reacts with water at about 150 .deg. C. Therefore, the water-proof nitride fuel must be developed to apply to current LWRs. Several strategies to prevent or reduce the reaction of nitride fuel with water have been suggested. KAERI is developing uranium nitride-oxide composite fuel pellet that is expected to have higher fuel performance and lower water reactivity. In the development of the fabrication technologies of uranium based composite fuel pellet, uranium nitride powder should be prepared, first. We have considered a simple reaction method to fabricate uranium nitride powders directly from metal uranium powders. Also, to create reactive uranium powder with nitrogen, it is applied that the uranium powder is pretreated in the hydrogen atmosphere. In this study, to investigate the behavior of the uranium powder hydriding process, thermal analysis tests were performed

  5. Optical hydrogen sensors based on metal-hydrides

    Science.gov (United States)

    Slaman, M.; Westerwaal, R.; Schreuders, H.; Dam, B.

    2012-06-01

    For many hydrogen related applications it is preferred to use optical hydrogen sensors above electrical systems. Optical sensors reduce the risk of ignition by spark formation and are less sensitive to electrical interference. Currently palladium and palladium alloys are used for most hydrogen sensors since they are well known for their hydrogen dissociation and absorption properties at relatively low temperatures. The disadvantages of palladium in sensors are the low optical response upon hydrogen loading, the cross sensitivity for oxygen and carbon, the limited detection range and the formation of micro-cracks after some hydrogen absorption/desorption cycles. In contrast to Pd, we find that the use of magnesium or rear earth bases metal-hydrides in optical hydrogen sensors allow tuning of the detection levels over a broad pressure range, while maintaining a high optical response. We demonstrate a stable detection layer for detecting hydrogen below 10% of the lower explosion limit in an oxygen rich environment. This detection layer is deposited at the bare end of a glass fiber as a micro-mirror and is covered with a thin layer of palladium. The palladium layer promotes the hydrogen uptake at room temperature and acts as a hydrogen selective membrane. To protect the sensor for a long time in air a final layer of a hydrophobic fluorine based coating is applied. Such a sensor can be used for example as safety detector in automotive applications. We find that this type of fiber optic hydrogen sensor is also suitable for hydrogen detection in liquids. As example we demonstrate a sensor for detecting a broad range of concentrations in transformer oil. Such a sensor can signal a warning when sparks inside a high voltage power transformer decompose the transformer oil over a long period.

  6. Metal hydride heat pump engineering demonstration and evaluation model

    Science.gov (United States)

    Lynch, Franklin E.

    1993-01-01

    Future generations of portable life support systems (PLSS's) for space suites (extravehicular mobility units or EMU's) may require regenerable nonventing thermal sinks (RNTS's). For purposes of mobility, a PLSS must be as light and compact as possible. Previous venting PLSS's have employed water sublimators to reject metabolic and equipment heat from EMU's. It is desirable for long-duration future space missions to minimize the use of water and other consumables that need to be periodically resupplied. The emission of water vapor also interferes with some types of instrumentation that might be used in future space exploration. The test article is a type of RNTS based on a metal hydride heat pump (MHHP). The task of reservicing EMU's after use must be made less demanding in terms of time, procedures, and equipment. The capability for quick turnaround post-EVA servicing (30 minutes) is a challenging requirement for many of the RNTS options. The MHHP is a very simple option that can be regenerated in the airlock within the 30 minute limit by the application of a heating source and a cooling sink. In addition, advanced PLSS's must provide a greater degree of automatic control, relieving astronauts of the need to manually adjust temperatures in their liquid cooled ventilation garments (LCVG's). The MHHP includes automatic coolant controls with the ability to follow thermal load swings from minimum to maximum in seconds. The MHHP includes a coolant loop subsystem with pump and controls, regeneration equipment for post-EVA servicing, and a PC-based data acquisition and control system (DACS).

  7. Mechanism of negative hydrogen ion emission from heated saline hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Kawano, Hiroyuki; Serizawa, Naoshi; Takeda, Makiko; Hasegawa, Seiji [Ehime Univ., Matsuyama (Japan). Faculty of Science

    1997-02-01

    To find a clue to the mechanism of negative hydrogen ion emission from a heated sample ({approx}10 mg) of powdery saline hydride (LiH or CaH{sub 2}) deposited on a molybdenum ribbon ({approx}0.1 cm{sup 2}), both the ionic and electronic emission currents were measured as a function of sample temperature ({approx}700 - 800 K), thereby yielding {approx}10{sup -15} - 10{sup -12} A of H{sup -} after mass analysis and {approx}10{sup -7} - 10{sup -5} A of thermal electron. Thermophysical analysis of these data indicates that the desorption energy (E{sup -}) of H{sup -} and work function ({phi}) of the emitting sample surface are 5.1 {+-} 0.3 and 3.1 {+-} 0.2 eV for LiH, respectively, while E{sup -} is 7.7 {+-} 0.3 eV and {phi} is 5.0 {+-} 0.2 eV for CaH{sub 2}. Thermochemical analysis based on our simple model on the emissions indicates that the values of E{sup -} - {phi} are 2.35 and 2.31 eV for LiH and CaH{sub 2}, respectively, which are in fair agreement with the respective values (2.1 {+-} 0.3 and 2.6 {+-} 0.3 eV) determined experimentally. This agreement indicates that the emission of H{sup -} is reasonably explained by our model from the viewpoint of reaction energy. (author)

  8. Ful distil ation argon producing crud argon column on operating experience%全精馏制氩粗氩塔操作经验浅谈

    Institute of Scientific and Technical Information of China (English)

    马光显

    2015-01-01

    This paper briefly introduces the ful distil ation argon recovery process in the crude argon column in air separation system of cooling,heating and put some matters needing attention in use.%简要介绍了全精馏制氩过程中粗氩塔在空分系统降温、升温及投用中的一些注意事项。

  9. Hydrogen storage: hydrogen as a hydride. 1974-May, 1980 (citations from the NTIS Data Base). Report for 1974-May 80. [135 abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Cavagnaro, D.M.

    1980-06-01

    The bibliography covers hydrogen storage as a hydride. Topics include the chemical and physical properties of the hydride, and how useful it may be for hydrogen storage. Also considered is the conversion of hydrogen to a hydride and the conversion back to hydrogen. (This updated bibliography contains 135 abstracts, 14 of which are new entries to the previous edition.)

  10. Development of Hydrogen Storage Tank Systems Based on Complex Metal Hydrides

    Directory of Open Access Journals (Sweden)

    Morten B. Ley

    2015-09-01

    Full Text Available This review describes recent research in the development of tank systems based on complex metal hydrides for thermolysis and hydrolysis. Commercial applications using complex metal hydrides are limited, especially for thermolysis-based systems where so far only demonstration projects have been performed. Hydrolysis-based systems find their way in space, naval, military and defense applications due to their compatibility with proton exchange membrane (PEM fuel cells. Tank design, modeling, and development for thermolysis and hydrolysis systems as well as commercial applications of hydrolysis systems are described in more detail in this review. For thermolysis, mostly sodium aluminum hydride containing tanks were developed, and only a few examples with nitrides, ammonia borane and alane. For hydrolysis, sodium borohydride was the preferred material whereas ammonia borane found less popularity. Recycling of the sodium borohydride spent fuel remains an important part for their commercial viability.

  11. Titanium tritide radioisotope heat source development : palladium-coated titanium hydriding kinetics and tritium loading tests.

    Energy Technology Data Exchange (ETDEWEB)

    Van Blarigan, Peter; Shugard, Andrew D.; Walters, R. Tom (Savannah River National Labs, Aiken, SC)

    2012-01-01

    We have found that a 180 nm palladium coating enables titanium to be loaded with hydrogen isotopes without the typical 400-500 C vacuum activation step. The hydriding kinetics of Pd coated Ti can be described by the Mintz-Bloch adherent film model, where the rate of hydrogen absorption is controlled by diffusion through an adherent metal-hydride layer. Hydriding rate constants of Pd coated and vacuum activated Ti were found to be very similar. In addition, deuterium/tritium loading experiments were done on stacks of Pd coated Ti foil in a representative-size radioisotope heat source vessel. The experiments demonstrated that such a vessel could be loaded completely, at temperatures below 300 C, in less than 10 hours, using existing department-of-energy tritium handling infrastructure.

  12. Hydride formation thermodynamics and hysteresis in individual Pd nanocrystals with different size and shape.

    Science.gov (United States)

    Syrenova, Svetlana; Wadell, Carl; Nugroho, Ferry A A; Gschneidtner, Tina A; Diaz Fernandez, Yuri A; Nalin, Giammarco; Świtlik, Dominika; Westerlund, Fredrik; Antosiewicz, Tomasz J; Zhdanov, Vladimir P; Moth-Poulsen, Kasper; Langhammer, Christoph

    2015-12-01

    Physicochemical properties of nanoparticles may depend on their size and shape and are traditionally assessed in ensemble-level experiments, which accordingly may be plagued by averaging effects. These effects can be eliminated in single-nanoparticle experiments. Using plasmonic nanospectroscopy, we present a comprehensive study of hydride formation thermodynamics in individual Pd nanocrystals of different size and shape, and find corresponding enthalpies and entropies to be nearly size- and shape-independent. The hysteresis observed is significantly wider than in bulk, with details depending on the specifics of individual nanoparticles. Generally, the absorption branch of the hysteresis loop is size-dependent in the sub-30 nm regime, whereas desorption is size- and shape-independent. The former is consistent with a coherent phase transition during hydride formation, influenced kinetically by the specifics of nucleation, whereas the latter implies that hydride decomposition either occurs incoherently or via different kinetic pathways.

  13. Tailoring Thermodynamics and Kinetics for Hydrogen Storage in Complex Hydrides towards Applications.

    Science.gov (United States)

    Liu, Yongfeng; Yang, Yaxiong; Gao, Mingxia; Pan, Hongge

    2016-02-01

    Solid-state hydrogen storage using various materials is expected to provide the ultimate solution for safe and efficient on-board storage. Complex hydrides have attracted increasing attention over the past two decades due to their high gravimetric and volumetric hydrogen densities. In this account, we review studies from our lab on tailoring the thermodynamics and kinetics for hydrogen storage in complex hydrides, including metal alanates, borohydrides and amides. By changing the material composition and structure, developing feasible preparation methods, doping high-performance catalysts, optimizing multifunctional additives, creating nanostructures and understanding the interaction mechanisms with hydrogen, the operating temperatures for hydrogen storage in metal amides, alanates and borohydrides are remarkably reduced. This temperature reduction is associated with enhanced reaction kinetics and improved reversibility. The examples discussed in this review are expected to provide new inspiration for the development of complex hydrides with high hydrogen capacity and appropriate thermodynamics and kinetics for hydrogen storage. PMID:26638824

  14. Measured and calculated fast neutron spectra in a depleted uranium and lithium hydride shielded reactor

    Science.gov (United States)

    Lahti, G. P.; Mueller, R. A.

    1973-01-01

    Measurements of MeV neutron were made at the surface of a lithium hydride and depleted uranium shielded reactor. Four shield configurations were considered: these were assembled progressively with cylindrical shells of 5-centimeter-thick depleted uranium, 13-centimeter-thick lithium hydride, 5-centimeter-thick depleted uranium, 13-centimeter-thick lithium hydride, 5-centimeter-thick depleted uranium, and 3-centimeter-thick depleted uranium. Measurements were made with a NE-218 scintillation spectrometer; proton pulse height distributions were differentiated to obtain neutron spectra. Calculations were made using the two-dimensional discrete ordinates code DOT and ENDF/B (version 3) cross sections. Good agreement between measured and calculated spectral shape was observed. Absolute measured and calculated fluxes were within 50 percent of one another; observed discrepancies in absolute flux may be due to cross section errors.

  15. Properties of hydrogen permeation barrier on the surface of zirconium hydride

    Institute of Scientific and Technical Information of China (English)

    CHEN Weidong; WANG Lijun; HAN Lin; CHEN Song

    2008-01-01

    A hydrogen permeation barrier was manufactured by the in situ reaction of zirconium hydride with oxygen.A reduction in the hydrogen permeation of the oxide films was detected by measuring the mass difference of the zirconium hydride samples after the dehydrogenation experiment.The reaction of zirconium hydride with oxygen occurs only under the condition that the temperature is higher than 673 K in the oxygen partial pressure of 0.1 MPa.The oxide film is composed of two layers,a permeable oxide layer and a dense oxide layer,and the main phase of the oxide film is ZrO2 with baddeleyite structure.The XPS analysis shows that O-H bonds exist in the oxide film,which are helpful for resisting hydrogen diffusion through the oxide film.

  16. Behavior of Fatigue Crack Propagation for Grade 2 Titanium on the Hydride Formation

    International Nuclear Information System (INIS)

    Fatigue crack growth tests were carried out to investigate the crack growth behavior of hydrided ASTM Grade 2 Titanium plate at 25 .deg. C and 300 .deg. C. The hydride in the α type titanium was formed by ingressing H2 gas(100-300mbar) at 300 .deg. C-500 .deg. C. Fatigue crack growth rates of the Ti specimens at 300 .deg. C were higher than the growth rates at room temperature. The fatigue crack growth rates along the rolling direction were always higher than those of along the transverse rolling direction. The fatigue crack growth rate of hydrogen charged Ti was strongly dependent on the crack plane orientation in the rolled sheet and the arrangement of hydrides relative to the crack growth direction

  17. Influence of the crack-tip hydride concentration on the fracture toughness of Zircaloy-4

    Energy Technology Data Exchange (ETDEWEB)

    Bertolino, G. [LMS, CNRS UMR7649, Ecole Polytechnique, 91128 Palaiseau cedex (France)]. E-mail: bertolin@cab.cnea.gov.ar; Perez Ipina, J. [CONICET (Argentina); Universidad Nacional del Comahue, 8300 Neuquen (Argentina); Meyer, G. [Centro Atomico Bariloche, CNEA, 8400 Bariloche (Argentina); CONICET (Argentina)

    2006-01-01

    The influence of a hydrogen concentration gradient at the crack-tip and hydride platelet orientation on the fracture toughness, fracture mode and micromechanisms of a Zircaloy-4 commercial alloy was studied. Fracture toughness was measured on CT specimens and the analysis was performed in terms of J-integral resistance curves at temperatures ranging from 293 to 473 K. Fracture toughness results of specimens containing higher hydrides concentration near the crack-tip region, preferentially orientated in the crack plane, were compared to those obtained from specimens with a homogeneous hydrogen distribution and different platelet orientation; specimens were obtained by charging them in loaded and unloaded condition, respectively. Changes on both macroscopic and microscopic fracture behaviour were observed at temperatures ranging from 293 to 343 K, and the results show the relevance of both hydride concentration and platelet orientation. The existence of a ductile-to-brittle transition is discussed at the light of these new results.

  18. Computer simulation of the reflection of hydrogen and the sputtering of hydrogen from metal hydrides

    International Nuclear Information System (INIS)

    Reflection of 0.1 to 2 keV H atoms from Ti, Fe and their 'metal hydrides', together with the H sputtered from the latter, have been calculated using the binary collision cascade program MARLOWE. The fraction of particles and energy reflected is found to decrease with increasing hydrogen content of the metal hydride and this decrease is independent of the incident ion energy. It is found that the heavy metal atoms of the metal hydride are responsible for the reflection and that most of the sputtering is produced by the reflected ion as it exists through the surface layer. It is also found that tritium ions sputter H from 'FeH' much more effectively than H ions sputter T from 'FeT'. (Auth.)

  19. Computer simulation of the reflection of hydrogen and the sputtering of hydrogen from metal hydrides

    International Nuclear Information System (INIS)

    Reflection of 0.1 to 2 keV H atoms from Ti, Fe and their ''metal hydrides,'' together with the H sputtered from the latter, have been calculated using the binary collision cascade program MARLOWE. The fraction of particles and energy reflected is found to decrease with increasing hydrogen content of the metal hydride and this decrease is independent of the incident ion energy. It is found that the heavy metal atoms of the metal hydride are responsible for the reflection and that most of the sputtering is produced by the reflected ion as it exits through the surface layer. It is also found that tritium ions sputter H from ''FeH'' much more effectively than H ions sputter T from ''FeT.''

  20. Pulsed laser deposition of air-sensitive hydride epitaxial thin films: LiH

    Directory of Open Access Journals (Sweden)

    Hiroyuki Oguchi

    2015-09-01

    Full Text Available We report on the epitaxial thin film growth of an air-sensitive hydride, lithium hydride (LiH, using pulsed laser deposition (PLD. We first synthesized a dense LiH target, which is key for PLD growth of high-quality hydride films. Then, we obtained epitaxial thin films of [100]-oriented LiH on a MgO(100 substrate at 250 °C under a hydrogen pressure of 1.3 × 10−2 Pa. Atomic force microscopy revealed that the film demonstrates a Stranski-Krastanov growth mode and that the film with a thickness of ∼10 nm has a good surface flatness, with root-mean-square roughness RRMS of ∼0.4 nm.

  1. Structure and Dynamics of Perovskite Hydrides: AMgH3, A=Na,K,Rb

    Energy Technology Data Exchange (ETDEWEB)

    Fornari, M. [Central Michigan University, Mt. Pleasant; Subedi, Alaska P [ORNL; Singh, David J [ORNL

    2007-01-01

    We report density functional studies of the structure and dynamics of NaMgH{sub 3}, KMgH{sub 3}, and RbMgH{sub 3} in the cubic perovskite structure as well as the corresponding fluorides and the alloy (Na,Li)MgH{sub 3}. The hydrides are ionic materials with structural properties very similar to fluorides. However, even though the structures of the hydrides and fluorides are very similar, we find that the dynamics can be quite different. We ascribe these differences to breathing of the hydride ion. This is also reflected in a reduced tendency toward Li off-centering in (Na,Li)MgH{sub 3}.

  2. An Investigation on the Persistence of Uranium Hydride during Storage of Simulant Nuclear Waste Packages.

    Directory of Open Access Journals (Sweden)

    C A Stitt

    Full Text Available Synchrotron X-rays have been used to study the oxidation of uranium and uranium hydride when encapsulated in grout and stored in de-ionised water for 10 months. Periodic synchrotron X-ray tomography and X-ray powder diffraction have allowed measurement and identification of the arising corrosion products and the rates of corrosion. The oxidation rates of the uranium metal and uranium hydride were slower than empirically derived rates previously reported for each reactant in an anoxic water system, but without encapsulation in grout. This was attributed to the grout acting as a physical barrier limiting the access of oxidising species to the uranium surface. Uranium hydride was observed to persist throughout the 10 month storage period and industrial consequences of this observed persistence are discussed.

  3. Compensation Effect in the Hydrogenation/Dehydrogenation Kinetics of Metal Hydrides

    DEFF Research Database (Denmark)

    Andreasen, A.; Vegge, T.; Pedersen, Allan Schrøder

    2005-01-01

    The possible existence of a compensation effect, i.e. concurrent changes in activation energy and prefactor, is investigated for the hydrogenation and dehydrogenation kinetics of metal hydrides, by analyzing a series of reported kinetic studies on Mg and LaNi5 based hydrides. For these systems, we...... find a clear linear relation between apparent prefactors and apparent activation energies, as obtained from an Arrhenius analysis, indicating the existence of a compensation effect. Large changes in apparent activation energies in the case of Mg based hydrides are rationalized in terms of a dependency...... of observed apparent activation energy on the degree of surface oxidation, i.e., a physical effect. On the other hand, we find the large concurrent changes in apparent prefactors to be a direct result of the Arrhenius analysis. Thus, we find the observed compensation effect to be an artifact of the data...

  4. Pulsed laser deposition of air-sensitive hydride epitaxial thin films: LiH

    Energy Technology Data Exchange (ETDEWEB)

    Oguchi, Hiroyuki, E-mail: oguchi@nanosys.mech.tohoku.ac.jp [Department of Nanomechanics, Tohoku University, Sendai 980-8579 (Japan); Micro System Integration Center (muSIC), Tohoku University, Sendai 980-0845 (Japan); Isobe, Shigehito [Creative Research Institution, Hokkaido University, Sapporo 001-0021 (Japan); Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Kuwano, Hiroki [Department of Nanomechanics, Tohoku University, Sendai 980-8579 (Japan); Shiraki, Susumu; Hitosugi, Taro [Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577 (Japan); Orimo, Shin-ichi [Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577 (Japan); Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2015-09-01

    We report on the epitaxial thin film growth of an air-sensitive hydride, lithium hydride (LiH), using pulsed laser deposition (PLD). We first synthesized a dense LiH target, which is key for PLD growth of high-quality hydride films. Then, we obtained epitaxial thin films of [100]-oriented LiH on a MgO(100) substrate at 250 °C under a hydrogen pressure of 1.3 × 10{sup −2} Pa. Atomic force microscopy revealed that the film demonstrates a Stranski-Krastanov growth mode and that the film with a thickness of ∼10 nm has a good surface flatness, with root-mean-square roughness R{sub RMS} of ∼0.4 nm.

  5. Hydride heat pump. Volume I. Users manual for HYCSOS system design program. [HYCSOS code

    Energy Technology Data Exchange (ETDEWEB)

    Gorman, R.; Moritz, P.

    1978-05-01

    A method for the design and costing of a metal hydride heat pump for residential use and a computer program, HYCSOS, which automates that method are described. The system analyzed is one in which a metal hydride heat pump can provide space heating and space cooling powered by energy from solar collectors and electric power generated from solar energy. The principles and basic design of the system are presented, and the computer program is described giving detailed design and performance equations used in the program. The operation of the program is explained, and a sample run is presented. This computer program is part of an effort to design, cost, and evaluate a hydride heat pump for residential use. The computer program is written in standard Fortran IV and was run on a CDC Cyber 74 and Cyber 174 computer. A listing of the program is included as an appendix. This report is Volume 1 of a two-volume document.

  6. Digestion and preparation methods of different samples determine elements produced hydride generation

    International Nuclear Information System (INIS)

    The aim of this work is to explain the principle of hydride generation technique, which is another technique of atomic absorption spectrometry, in addition to flame and graphite techniques. This technique is used to determine some metals and nonmetals (Se, Sn, Te, Sb, Bi, AS, Hg ) which produce volatile compounds in their reactions. The study focuses on the analytical capabilities of the hydride generation technique, the principle of hydride generation process, the interferences that affect the analysis process (spectra interference, chemical interference, kinetic interference, oxidation state interference, gas layer interference) and the methods to overcome these interferences. The working steps of the technique have been reported, finally some experimental work has been performed on different kind of samples such as: waste, tripolyphosphate, volcanic rock and phosphogypsum to determine mercury and blood sample to determine arsenic. (Authors)

  7. Impedance and self-discharge mechanism studies of nickel metal hydride batteries for energy storage applications

    Science.gov (United States)

    Zhu, Wenhua; Zhu, Ying; Tatarchuk, Bruce

    2013-04-01

    Nickel metal hydride battery packs have been found wide applications in the HEVs (hybrid electric vehicles) through the on-board rapid energy conservation and efficient storage to decrease the fossil fuel consumption rate and reduce CO2 emissions as well as other harmful exhaust gases. In comparison to the conventional Ni-Cd battery, the Ni-MH battery exhibits a relatively higher self-discharge rate. In general, there are quite a few factors that speed up the self-discharge of the electrodes in the sealed nickel metal hydride batteries. This disadvantage eventually reduces the overall efficiency of the energy conversion and storage system. In this work, ac impedance data were collected from the nickel metal hydride batteries. The self-discharge mechanism and battery capacity degradation were analyzed and discussed for further performance improvement.

  8. Strain evolution during hydride precipitation in Zircaloy-4 observed with synchrotron X-ray diffraction

    Science.gov (United States)

    Blackmur, M. S.; Preuss, M.; Robson, J. D.; Zanellato, O.; Cernik, R. J.; Ribeiro, F.; Andrieux, J.

    2016-06-01

    Synchrotron X-ray diffraction was used to evaluate strain evolution observed in Zircaloy-4 undergoing hydride precipitation during a range of thermal operations. During continuous heating, a change in the constraining effect of the matrix was observed at a temperature of 280 °C, thought to be the result of matrix dilatation from interstitial hydrogen. A deconvolution of the thermal, chemical and mechanical sources of strain during quench and dwell operations identified a non-negligible mechanical effect in the matrix. During these dwells, slow strain rate relaxation of elastic strains was seen in the matrix and hydride, suggesting that time dependent relaxation of misfit stresses may be possible at reactor relevant temperatures. Notable anisotropy was observed between the rolling and transverse directions, identified as being the likely product of a similar anisotropy in the relaxation of the hydride misfit between the α and α matrix directions, owing to the differing coherency of these two interfaces.

  9. Formation and physical properties of uranium hydride under conditions relevant to metallic fuel and nuclear waste storage

    Science.gov (United States)

    Orr, Robin; Godfrey, Hugh; Broan, Chris; Goddard, Dave; Woodhouse, Guy; Durham, Peter; Diggle, Andrew; Bradshaw, John

    2016-08-01

    The formation of uranium hydride is recognised as a hazard during the storage of uranium metal owing to its potentially pyrophoric properties. This study has assessed the influence of water vapour on the potential for uranium hydride to form at low temperatures and shows that it increases the duration of the induction period but does not necessarily prevent uranium hydride formation and also does not significantly change the reaction rate with hydrogen. It is further shown that the α-UH3 fraction in the uranium hydride gradually increases at decreasing temperatures and is likely to be the dominant phase formed under typical storage conditions. Particle morphology and specific surface area of uranium hydride prepared between 30 °C and 200 °C have also been characterised but show only modest variation compared with the phase composition.

  10. Study of hydride blisters in Zr-alloy using neutron tomography

    International Nuclear Information System (INIS)

    Highlights: ► We have established neutron tomography as a potential tool for the study of blister formation. ► Location, size and hydride distribution in the vicinity of blisters has been imaged. ► Hydrogen concentration up to 25 wppm in the reconstructed images has been detected. ► Linear relation between mode of image histogram and hydrogen concentration has been found. ► Spatial in-homogeneity of hydride distribution has also been identified in tomographic images. - Abstract: Formation of hydride blisters in Zircaloy pressure tubes of pressurized heavy water reactor (PHWR) is a major life limiting factor which hinders the safe and uninterrupted operation of the reactor. Nondestructive detection and evaluation of location and size of these blisters as well as hydride distribution in the matrix surrounding them may help in damage quantification and residual life extension. In this article we present the neutron tomography studies carried out on simulated hydride blister samples grown on Zircaloy tubes. Characterization on samples having various levels of hydrogen concentrations were also carried out for quantification of the detectability of our neutron tomography system. We could identify the spatial in-homogeneity of hydride concentration present in the samples. Quantitatively hydrogen concentration difference up to 25 wppm has been observed experimentally and calibrated against image intensity in the reconstructed image. This study establishes neutron tomography as a potential non-destructive evaluation tool for the estimation of the severity of damage in the integrity of the pressure tubes and provides valuable information about kinetics of blister formation.

  11. Ultrasonic estimation of hydride degradation of zirconium pressure tubes of RBMK fuel channel

    International Nuclear Information System (INIS)

    Fuel channels of nuclear reactors, which are major structural elements of a reactor core, have to meet strict requirements in terms of operational reliability. The middle part of the fuel channel, located in a graphite stack, is a tube made of a zirconium-2.5% niobium alloy. However, zirconium alloys can pick up hydrogen during operation as a consequence of corrosion reaction with water. Hydrogen redistributes easily at elevated temperatures migrating down a temperature or concentration gradient and up a stress gradient. When the terminal solid solubility is exceeded in a component such as a pressure tube that is highly stressed for long periods of time, delayed hydride cracking failures may occur. To estimate degradation of the zirconium alloy in the presence of hydrides, predetermined amounts of hydrogen were added to the sections of the fuel channel tubes by electrolytic deposition of a layer of hydride on the surface of the pressure tube material followed by dissolving the hydride layer by diffusion annealing at an elevated temperature. For estimation of the concentration of zirconium hydride platelets in the zirconium alloy test samples ultrasonic testing methods were proposed. The first method is based on precise measurement of velocity of longitudinal and shear wave at different directions and the second is based on the investigation of high frequency ultrasonic signals backscattered in a focal zone of an ultrasonic transducer. The experimental investigations were performed on the zirconium alloy samples of different concentration of hydrides in the immersion tank at a room temperature. The results obtained on testing samples using different excitation conditions and different types of ultrasonic waves are presented. (orig.)

  12. Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol

    Science.gov (United States)

    Sun, Wen-Ting; Li, Guo; Li, He-Ping; Bao, Cheng-Yu; Wang, Hua-Bo; Zeng, Shi; Gao, Xing; Luo, Hui-Ying

    2007-06-01

    Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure α-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.

  13. First measurements with ARGONTUBE, a 5 m long drift Liquid Argon TPC

    International Nuclear Information System (INIS)

    The Liquid Argon Time Projection Chamber (LAr TPC) technique is a promising technology for future neutrino detectors. At LHEP of the University of Bern (Switzerland), an R and D program towards large detectors are on-going. The main goal is to show the feasibility of long drift paths over many meters. Therefore, a liquid Argon TPC with 5 m of drift distance was constructed. Many other aspects of the liquid Argon TPC technology are also investigated, such as a new device to generate high voltage in liquid Argon (Greinacher circuit), a recirculation filtering system and the multi-photon ionization of liquid Argon with a UV laser. Two detectors are built: a medium size prototype for specific detector technology studies, and ARGONTUBE, a 5 m long device

  14. Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol

    International Nuclear Information System (INIS)

    Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure α-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images

  15. First measurement of the ionization yield of nuclear recoils in liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, T. [Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering; Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Sangiorgio, Samuele [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Bernstein, A. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Foxe, Michael P. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical and Nuclear Engineering; Hagmann, Chris [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Jovanovic, Igor [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical and Nuclear Engineering; Kazkaz, K. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Mozin, Vladimir V. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Norman, E. B. [Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering; Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Pereverzev, S. V. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Rebassoo, Finn O. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Sorensen, Peter F. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

    2014-05-01

    Liquid phase argon has long been used as a target medium for particle detection via scintillation light. Recently there has been considerable interest in direct detection of both hypothetical darkmatter particles and coherent elastic neutrino nucleus scattering. These as-yet unobserved neutral particle interactions are expected to result in a recoiling argon atom O(keV), generally referred to in the literature as a nuclear recoil. This prompts the question of the available electromagnetic signal in a liquid argon detector. In this Letter we report the first measurement of the ionization yield (Qy), detected electrons per unit energy, resulting from nuclear recoils in liquid argon, measured at 6.7 keV. This is also the lowest energy measurement of nuclear recoils in liquid argon.

  16. Management of Liver Cancer Argon-helium Knife Therapy with Functional Computer Tomography Perfusion Imaging.

    Science.gov (United States)

    Wang, Hongbo; Shu, Shengjie; Li, Jinping; Jiang, Huijie

    2016-02-01

    The objective of this study was to observe the change in blood perfusion of liver cancer following argon-helium knife treatment with functional computer tomography perfusion imaging. Twenty-seven patients with primary liver cancer treated with argon-helium knife and were included in this study. Plain computer tomography (CT) and computer tomography perfusion (CTP) imaging were conducted in all patients before and after treatment. Perfusion parameters including blood flows, blood volume, hepatic artery perfusion fraction, hepatic artery perfusion, and hepatic portal venous perfusion were used for evaluating therapeutic effect. All parameters in liver cancer were significantly decreased after argon-helium knife treatment (p liver tissue, but other parameters kept constant. CT perfusion imaging is able to detect decrease in blood perfusion of liver cancer post-argon-helium knife therapy. Therefore, CTP imaging would play an important role for liver cancer management followed argon-helium knife therapy.

  17. Carbon enhanced hydriding of oxidized U-0.1wt%Cr surfaces

    Science.gov (United States)

    Shamir, N.; Schweke, D.; Rubin, A.; Livneh, T.; Zalkind, S.

    2010-03-01

    The effect of deposited amorphous carbon on the reactivity of uranium towards hydridization has been investigated by means of optical (HSM), electron (SEM), Raman scattering and atomic force (AFM) microscopies. Clear preference was found towards hydrogen attack on the carbon covered area as mostly manifested by the formation of hollow blister-like hydrides with average height of ~1μm, and crust of few hundreds of nm. NOTE: As a result of an inadvertent AN2009 editorial error that led to publication of non-finalized version the PDF was replaced with the correct version on 16 September 2010. The original PDF can be found in the supplementary data.

  18. Ruthenium hydride-promoted dienyl isomerization: access to highly substituted 1,3-dienes.

    Science.gov (United States)

    Clark, Joseph R; Griffiths, Justin R; Diver, Steven T

    2013-03-01

    Ruthenium hydrides were found to promote the positional isomerization of 1,3-dienes into more highly substituted 1,3-dienes in a stereoconvergent manner. The reaction can be conducted in one pot starting with terminal alkynes and alkenes by triggering decomposition of the Grubbs catalyst into a ruthenium hydride, which promotes the dienyl isomerization. The presence of an alcohol additive plays a helpful role in the reaction, significantly increasing the chemical yields. Mechanistic studies are consistent with hydrometalation of the geminally substituted alkene of the 1,3-diene and transit of the ruthenium atom across the diene framework via a π-allylruthenium intermediate. PMID:23427813

  19. Elemental step thermodynamics of various analogues of indazolium alkaloids to obtaining hydride in acetonitrile.

    Science.gov (United States)

    Lei, Nan-Ping; Fu, Yan-Hua; Zhu, Xiao-Qing

    2015-12-21

    A series of analogues of indazolium alkaloids were designed and synthesized. The thermodynamic driving forces of the 6 elemental steps for the analogues of indazolium alkaloids to obtain hydride in acetonitrile were determined using an isothermal titration calorimeter (ITC) and electrochemical methods, respectively. The effects of molecular structure and substituents on the thermodynamic driving forces of the 6 steps were examined. Meanwhile, the oxidation mechanism of NADH coenzyme by indazolium alkaloids was examined using the chemical mimic method. The result shows that the oxidation of NADH coenzyme by indazolium alkaloids in vivo takes place by one-step concerted hydride transfer mechanism.

  20. White Paper Summary of 2nd ASTM International Workshop on Hydrides in Zirconium Alloy Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Sindelar, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Louthan, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); PNNL, B. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-05-29

    This white paper recommends that ASTM International develop standards to address the potential impact of hydrides on the long term performance of irradiated zirconium alloys. The need for such standards was apparent during the 2nd ASTM International Workshop on Hydrides in Zirconium Alloy Cladding and Assembly Components, sponsored by ASTM International Committee C26.13 and held on June 10-12, 2014, in Jackson, Wyoming. The potentially adverse impacts of hydrogen and hydrides on the long term performance of irradiated zirconium-alloy cladding on used fuel were shown to depend on multiple factors such as alloy chemistry and processing, irradiation and post irradiation history, residual and applied stresses and stress states, and the service environment. These factors determine the hydrogen content and hydride morphology in the alloy, which, in turn, influence the response of the alloy to the thermo-mechanical conditions imposed (and anticipated) during storage, transport and disposal of used nuclear fuel. Workshop presentations and discussions showed that although hydrogen/hydride induced degradation of zirconium alloys may be of concern, the potential for occurrence and the extent of anticipated degradation vary throughout the nuclear industry because of the variations in hydrogen content, hydride morphology, alloy chemistry and irradiation conditions. The tools and techniques used to characterize hydrides and hydride morphologies and their impacts on material performance also vary. Such variations make site-to-site comparisons of test results and observations difficult. There is no consensus that a single material or system characteristic (e.g., reactor type, burnup, hydrogen content, end-of life stress, alloy type, drying temperature, etc.) is an effective predictor of material response during long term storage or of performance after long term storage. Multi-variable correlations made for one alloy may not represent the behavior of another alloy exposed to

  1. A semi-empirical approach to accurate standard enthalpies of formation for solid hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Klaveness, A. [Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo (Norway)], E-mail: arnekla@kjemi.uio.no; Fjellvag, H.; Kjekshus, A.; Ravindran, P. [Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, N-0315 Oslo (Norway); Swang, O. [SINTEF Materials and Chemistry, P.O. Box 124, Blindern, N-0314 Oslo (Norway)

    2009-02-05

    A semi-empirical method for estimation of enthalpies of formation of solid hydrides is proposed. The method is named Ionic for short. By combining experimentally known enthalpies of formation for simple hydrides and reaction energies computed using band-structure density functional theory (DFT) methods, startling accurate results can be achieved. The approach relies on cancellation of errors when comparing DFT energies for systems with similar electronic structures. The influence of zero-point energies, polaritons, and vibrational excitations on the results has been examined and found to be minor.

  2. Effect of preparation method of metal hydride electrode on efficiency of hydrogen electrosorption process

    Energy Technology Data Exchange (ETDEWEB)

    Giza, Krystyna [Czestochowa University of Technology (Poland). Faculty of Production Engineering and Materials Technology; Drulis, Henryk [Trzebiatowski Institute of Low Temperatures and Structure Research PAS, Wroclaw (Poland)

    2016-02-15

    The preparation of negative electrodes for nickel-metal hydride batteries using LaNi{sub 4.3}Co{sub 0.4}Al{sub 0.3} alloy is presented. The constant current discharge technique is employed to determine the discharge capacity, the exchange current density and the hydrogen diffusion coefficient of the studied electrodes. The electrochemical performance of metal hydride electrode is strongly affected by preparation conditions. The results are compared and the advantages and disadvantages of preparation methods of the electrodes are also discussed.

  3. Effects of Hf on thermal and mechanical properties of Zr hydrides

    International Nuclear Information System (INIS)

    The polycrystalline fine bulk samples of δ-phase Zr hydrides with various Hf contents were prepared and their thermal and mechanical properties were investigated. In the temperature range from room temperature to 973 K, the phase states were examined by high-temperature X-ray diffraction and thermogravimetry/differential thermal analyses. In the temperature range from room temperature to 673 K, the coefficient of linear thermal expansion, specific heat capacity, and thermal conductivity were evaluated. The Vickers hardness and sound velocity were measured at room temperature, and the elastic modulus was evaluated. The effects of Hf on the thermal and mechanical properties of Zr hydrides were studied. (author)

  4. Development of membrane cryostats for large liquid argon neutrino detectors

    CERN Document Server

    Montanari, D; Gendotti, A; Geynisman, M; Hentschel, S; Loew, T; Mladenov, D; Montanari, C; Murphy, S; Nessi, M; Norris, B; Noto, F; Rubbia, A; Sharma, R; Smargianaki, D; Stewart, J; Vignoli, C; Wilson, P; Wu, S

    2015-01-01

    A new collaboration is being formed to develop a multi-kiloton Long-Baseline neutrino experiment that will be located at the Surf Underground Research Facility (SURF) in Lead, SD. In the present design, the detector will be located inside cryostats filled with 68,400 ton of ultrapure liquid argon (less than 100 parts per trillion of oxygen equivalent contamination). To qualify the membrane technology for future very large-scale and underground implementations, a strong prototyping effort is ongoing: several smaller detectors of growing size with associated cryostats and cryogenic systems will be designed and built at Fermilab and CERN. They will take physics data and test different detector elements, filtration systems, design options and installation procedures. In addition, a 35 ton prototype is already operational at Fermilab and will take data with single-phase detector in early 2016. After the prototyping phase, the multi-kton detector will be constructed. After commissioning, it will detect and study ne...

  5. Fluorescence Spectrum of SiO in an Argon Matrix

    Science.gov (United States)

    Scullman, R.; Hormes, J.; Schroeder, W.; Wiggenhauser, H.

    1987-04-01

    Fluorescence from SiO matrix isolated in argon has been investigated in the wavelength region 120-300 nm. Fluorescence emission spectra from the valence states, A1Π, E1Σ+ and G1Π, revealed that nearly all radiation comes from one channel at 305 nm, which was analysed as originating from the b3Π-X1Σ+ transition. Contrary to the A1Π and G1Π states, the E1Σ+ state also decays radiatively, although weakly, through two other channels situated in the vicinity of 305 nm. These two channels were believed to originate from the a3Σ+-X1Σ+ and e3Σ--X1Σ+ transitions.

  6. Electron Neutrino Classification in Liquid Argon Time Projection Chamber Detector

    CERN Document Server

    Płoński, Piotr; Sulej, Robert; Zaremba, Krzysztof

    2015-01-01

    Neutrinos are one of the least known elementary particles. The detection of neutrinos is an extremely difficult task since they are affected only by weak sub-atomic force or gravity. Therefore large detectors are constructed to reveal neutrino's properties. Among them the Liquid Argon Time Projection Chamber (LAr-TPC) detectors provide excellent imaging and particle identification ability for studying neutrinos. The computerized methods for automatic reconstruction and identification of particles are needed to fully exploit the potential of the LAr-TPC technique. Herein, the novel method for electron neutrino classification is presented. The method constructs a feature descriptor from images of observed event. It characterizes the signal distribution propagated from vertex of interest, where the particle interacts with the detector medium. The classifier is learned with a constructed feature descriptor to decide whether the images represent the electron neutrino or cascade produced by photons. The proposed ap...

  7. Large area liquid argon detectors for interrogation systems

    Energy Technology Data Exchange (ETDEWEB)

    Gary, Charles; Kane, Steve; Firestone, Murray I.; Smith, Gregory [Adelphi Technology LLC, Purdue Technology Center, 5225 Exploration Drive, Indianapolis, IN 46241 (United States); Gozani, Tsahi; Brown, Craig; Kwong, John; King, Michael J. [Rapiscan Laboratories, 520 Almanor Avenue, Sunnyvale, CA 94085 (United States); Nikkel, James A.; McKinsey, Dan [Physics Department, Yale University, New Haven, CT 06520 (United States)

    2013-04-19

    Measurements of the efficiency, pulse shape, and energy and time resolution of liquid argon (LAr) detectors are presented. Liquefied noble gas-based (LNbG) detectors have been developed for the detection of dark matter and neutrinoless double-beta decay. However, the same qualities that make LNbG detectors ideal for these applications, namely their size, cost, efficiency, pulse shape discrimination and resolution, make them promising for portal screening and the detection of Special Nuclear Materials (SNM). Two 18-liter prototype detectors were designed, fabricated, and tested, one with pure LAr and the other doped with liquid Xe (LArXe). The LArXe detector presented the better time and energy resolution of 3.3 ns and 20% at 662 KeV, respectively. The total efficiency of the detector was measured to be 35% with 4.5% of the total photons detected in the photopeak.

  8. Argon plasma coagulation for treatment of hemorrhagic radiation gastroduodenitis

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Shu-Ji; Aoyama, Nobuo; Shirasaka, Daisuke; Inoue, Takashi; Kuroda, Kohei; Ebara, Shigeyuki; Tamura, Takao; Miyamoto, Masaki; Kasuga, Masato [Kobe Univ. (Japan). Graduate School of Medicine

    2002-01-01

    A 79-year-old man who had received radiotherapy for portal vein thrombosis due to hepatocellular carcinoma (HCC) 5 months earlier, showed progressive anemia and melena. Endoscopy on admission revealed diffuse bleeding from multiple telangiectasias on the anterior wall of the antrum and bulbus. We treated this patient with a new non-contact hemostatic method: the argon plasma coagulator (APC). The melena stopped after the first session and the hemoglobin level remained stable for 7 months. No delayed complications have been observed. Gastrointestinal bleeding from chronic radiation gastroduodenitis is rarely reported compared with radiation proctitis. This case demonstrates that APC is effective for hemostasis of diffuse bleeding from radiation gastroduodenitis, just as for radiation protitis. (author)

  9. Line ratio diagnostics in helium and helium seeded argon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Boivin, R F [Department of Physics, Auburn University, Auburn, AL 36849-5311 (United States); Loch, S D [Department of Physics, Auburn University, Auburn, AL 36849-5311 (United States); Ballance, C P [Physics Department, Rollins College, White Park, FL 32789 (United States); Branscomb, D [Department of Physics, Auburn University, Auburn, AL 36849-5311 (United States); Pindzola, M S [Department of Physics, Auburn University, Auburn, AL 36849-5311 (United States)

    2007-08-15

    We investigate the potential use of line ratio diagnostics to evaluate electron temperature in either helium or helium seeded argon plasmas. Plasmas are produced in a helicon plasma source. A rf compensated Langmuir probe is used to measure both the electron temperature and plasma density while a spectrometer is used to measure He I line intensities from the plasma. For all plasma densities where the electron temperature remains at 5 {+-} 1 eV, three He line ratios are measured. Each experimental ratio is compared with the prediction of three different collisional radiative models. One of these models makes uses of recent R-matrix with pseudo-states calculations for collisional rate coefficients. A discussion related to the different observations and model predictions is presented.

  10. Photodegradation Mechanisms of Tetraphenyl Butadiene Coatings for Liquid Argon Detectors

    CERN Document Server

    Jones, B J P; Conrad, J M; Pla-Dalmau, A

    2013-01-01

    We report on studies of degradation mechanisms of tetraphenyl butadiene (TPB) coatings of the type used in neutrino and dark matter liquid argon experiments. Using gas chromatography coupled to mass spectrometry we have detected the ultraviolet-blocking impurity benzophenone (BP). We monitored the drop in performance and increase of benzophenone concentration in TPB plates with exposure to ultraviolet (UV) light, and demonstrate the correlation between these two variables. Based on the presence and initially exponential increase in the concentration of benzophenone observed, we propose that TPB degradation is a free radical-mediated photooxidation reaction, which is subsequently confirmed by displaying delayed degradation using a free radical inhibitor. Finally we show that the performance of wavelength-shifting coatings of the type envisioned for the LBNE experiment can be improved by 10-20%, with significantly delayed UV degradation, by using a 20% admixture of 4-tert-Butylcatechol.

  11. Kinetic modeling of the Townsend breakdown in argon

    Energy Technology Data Exchange (ETDEWEB)

    Macheret, S. O.; Shneider, M. N. [Department of Mechanical and Aerospace Engineering, Princeton University, D-414 Engineering Quadrangle, Princeton, New Jersey 08544 (United States)

    2013-10-15

    Kinetic modeling of the Townsend breakdown in argon was performed in the “forward-back” approximation. The kinetic model was found to adequately describe the left branch of the Paschen curve, and the important role of ionization by fast ions and atoms near the cathode, as well as the increase in secondary emission coefficient in strong electric fields described in the literature, was confirmed. The modeling also showed that the electron energy distribution function develops a beam of high-energy electrons and that the runaway effect, i.e., the monotonic increase of the mean electron energy with the distance from the cathode, occurs at the left branch of the Paschen curve.

  12. Uranium (III) precipitation in molten chloride by wet argon sparging

    Science.gov (United States)

    Vigier, Jean-François; Laplace, Annabelle; Renard, Catherine; Miguirditchian, Manuel; Abraham, Francis

    2016-06-01

    In the context of pyrochemical processes for nuclear fuel treatment, the precipitation of uranium (III) in molten salt LiCl-CaCl2 (30-70 mol%) at 705 °C is studied. First, this molten chloride is characterized with the determination of the water dissociation constant. With a value of 10-4.0, the salt has oxoacid properties. Then, the uranium (III) precipitation using wet argon sparging is studied. The salt is prepared using UCl3 precursor. At the end of the precipitation, the salt is totally free of solubilized uranium. The main part is converted into UO2 powder but some uranium is lost during the process due to the volatility of uranium chloride. The main impurity of the resulting powder is calcium. The consequences of oxidative and reductive conditions on precipitation are studied. Finally, coprecipitation of uranium (III) and neodymium (III) is studied, showing a higher sensitivity of uranium (III) than neodymium (III) to precipitation.

  13. The readout driver (ROD) for the ATLAS liquid argon calorimeters

    Science.gov (United States)

    Efthymiopoulos, Ilias

    2001-04-01

    The Readout Driver (ROD) for the Liquid Argon calorimeter of the ATLAS detector is described. Each ROD module receives triggered data from 256 calorimeter cells via two fiber-optics 1.28 Gbit/s links with a 100 kHz event rate (25 kbit/event). Its principal function is to determine the precise energy and timing of the signal from discrete samples of the waveform, taken each period of the LHC clock (25 ns). In addition, it checks, histograms, and formats the digital data stream. A demonstrator system, consisting of a motherboard and several daughter-board processing units (PUs) was constructed and is currently used for tests in the lab. The design of this prototype board is presented here. The board offers maximum modularity and allows the development and testing of different PU designs based on today's leading integer and floating point DSPs.

  14. Characterization of SF6/Argon Plasmas for Microelectronics Applications; TOPICAL

    International Nuclear Information System (INIS)

    This report documents measurements in inductively driven plasmas containing SF(sub 6)/Argon gas mixtures. The data in this report is presented in a series of appendices with a minimum of interpretation. During the course of this work we investigated: the electron and negative ion density using microwave interferometry and laser photodetachment; the optical emission; plasma species using mass spectrometry, and the ion energy distributions at the surface of the rf biased electrode in several configurations. The goal of this work was to assemble a consistent set of data to understand the important chemical mechanisms in SF(sub 6) based processing of materials and to validate models of the gas and surface processes

  15. Photodegradation mechanisms of tetraphenyl butadiene coatings for liquid argon detectors

    Science.gov (United States)

    Jones, B. J. P.; VanGemert, J. K.; Conrad, J. M.; Pla-Dalmau, A.

    2013-01-01

    We report on studies of degradation mechanisms of tetraphenyl butadiene (TPB) coatings of the type used in neutrino and dark matter liquid argon experiments. Using gas chromatography coupled to mass spectrometry we have detected the ultraviolet-blocking impurity benzophenone. We monitored the drop in performance and increase of benzophenone concentration in TPB plates with exposure to ultraviolet (UV) light, and demonstrate the correlation between these two variables. Based on the presence and initially exponential increase in the concentration of benzophenone observed, we propose that TPB degradation is a free radical-mediated photooxidation reaction, which is subsequently confirmed by displaying delayed degradation using a free radical inhibitor. Finally we show that the performance of wavelength-shifting coatings of the type envisioned for the LBNE experiment can be improved by 10-20%, with significantly delayed UV degradation, by using a 20% admixture of 4-tert-Butylcatechol.

  16. Liquid Argon Cryogenic Detector Calibration by Inelastic Scattering of Neutrons

    CERN Document Server

    Polosatkin, Sergey; Dolgov, Alexander

    2014-01-01

    A method for calibration of cryogenic liquid argon detector response to recoils with certain energy -8.2 keV - is proposed. The method utilizes a process of inelastic scattering of monoenergetic neutrons produced by fusion DD neutron generator. Features of kinematics of inelastic scattering cause sufficient (forty times) increase in count rate of useful events relative to traditional scheme exploited elastic scattering with the same recoil energy and compatible energy resolution. The benefits of the proposed scheme of calibration most well implemented with the use of tagged neutron generator as a neutron source that allows to eliminate background originated from casual coincidence of signals on cryogenic detector and additional detector of scattered neutrons.

  17. The liquid argon TPC for the ICARUS experiment

    CERN Document Server

    Arneodo, F

    1997-01-01

    The ICARUS project aims at the realisation of a large liquid argon TPC to be run at the Underground Laboratories of Gran Sasso in Italy. An intense R&D; activity has put on firm grounds this new detector technology and experimentally confirmed its feasibility on a few ton scale. Based on these solid achievements, the collaboration is now confident of being able to build and safely operate a multi-kton detector. The reseach program of the experiment involves the systematic study of a wide spectrum of physical phenomena covering many orders of magnitude in the energy deposited in the detector: from the few MeV of solar neutrino interactions, to the about one GeV of the proton decay and atmospheric neutrinos, up to the higher energies of neutrinos from accelerators.

  18. Response Uniformity of the ATLAS Liquid Argon Electromagnetic Calorimeter

    CERN Document Server

    Aharrouche, M; Di Ciaccio, L; El Kacimi, M; Gaumer, O; Gouanère, M; Goujdami, D; Lafaye, R; Laplace, S; Le Maner, C; Neukermans, L; Perrodo, P; Poggioli, L; Prieur, D; Przysiezniak, H; Sauvage, G; Wingerter-Seez, I; Zitoun, R; Lanni, F; Lü, L; Ma, H; Rajagopalan, S; Takai, H; Belymam, A; Benchekroun, D; Hakimi, M; Hoummada, A; Gao, Y; Stroynowsk, R; Aleksa, M; Carli, T; Fassnacht, P; Gianotti, F; Hervás, L; Lampl, W; Collot, J; Hostachy, J Y; Ledroit-Guillon, F; Malek, F; Martin, P; Viret, S; Leltchouk, M; Parsons, J A; Simion, S; Barreiro, F; Del Peso, J; Labarga, L; Oliver, C; Rodier, S; Barrillon, P; Benchouk, C; Djama, F; Hubaut, F; Monnier, E; Pralavorio, P; Sauvage, D; Serfon, C; Tisserant, S; Tóth, J; Banfi, D; Carminati, L; Cavalli, D; Costa, G; Delmastro, M; Fanti, M; Mandell, L; Mazzanti, M; Tartarelli, F; Kotov, K; Maslennikov, A; Pospelov, G; Tikhonov, Yu; Bourdarios, C; Fayard, L; Fournier, D; Iconomidou-Fayard, L; Kado, M; Parrour, G; Puzo, P; Rousseau, D; Sacco, R; Serin, L; Unal, G; Zerwas, D; Dekhissi, B; Derkaoui, J; EL Kharrim, A; Maaroufi, F; Cleland, W; Lacour, D; Laforge, B; Nikolic-Audit, I; Schwemling, Ph; Ghazlane, H; Cherkaoui El Moursli, R; Idrissi Fakhr-Eddine, A; Boonekamp, M; Kerschen, N; Mansoulié, B; Meyer, P; Schwindlingy, J; Lund-Jensen, B

    2007-01-01

    The construction of the ATLAS electromagnetic liquid argon calorimeter modules is completed and all the modules are assembled and inserted in the cryostats. During the production period four barrel and three endcap modules were exposed to test beams in order to assess their performance, ascertain the production quality and reproducibility, and to scrutinize the complete energy reconstruction chain from the readout and calibration electronics to the signal and energy reconstruction. It was also possible to check the full Monte Carlo simulation of the calorimeter. The analysis of the uniformity, resolution and extraction of constant term is presented. Typical non-uniformities of 0.5% and typical global constant terms of 0.6% are measured for the barrel and end-cap modules.

  19. A Thermodynamic Model for Argon Plasma Kernel Formation

    Directory of Open Access Journals (Sweden)

    James Keck

    2010-11-01

    Full Text Available Plasma kernel formation of argon is studied experimentally and theoretically. The experiments have been performed in a constant volume cylindrical vessel located in a shadowgraph system. The experiments have been done in constant pressure. The energy of plasma is supplied by an ignition system through two electrodes located in the vessel. The experiments have been done with two different spark energies to study the effect of input energy on kernel growth and its properties. A thermodynamic model employing mass and energy balance was developed to predict the experimental data. The agreement between experiments and model prediction is very good. The effect of various parameters such as initial temperature, initial radius of the kernel, and the radiation energy loss have been investigated and it has been concluded that initial condition is very important on formation and expansion of the kernel.

  20. The readout driver (ROD) for the ATLAS liquid argon calorimeters

    CERN Document Server

    Efthymiopoulos, I

    2001-01-01

    The Readout Driver (ROD) for the Liquid Argon calorimeter of the ATLAS detector is described. Each ROD module receives triggered data from 256 calorimeter cells via two fiber-optics 1.28 Gbit/s links with a 100 kHz event rate (25 kbit/event). Its principal function is to determine the precise energy and timing of the signal from discrete samples of the waveform, taken each period of the LHC clock (25 ns). In addition, it checks, histograms, and formats the digital data stream. A demonstrator system, consisting of a motherboard and several daughter-board processing units (PUs) was constructed and is currently used for tests in the lab. The design of this prototype board is presented here. The board offers maximum modularity and allows the development and testing of different PU designs based on today's leading integer and floating point DSPs. (3 refs).

  1. Attosecond Coherent Control of Single and Double Photoionization in Argon.

    Science.gov (United States)

    Hogle, C W; Tong, X M; Martin, L; Murnane, M M; Kapteyn, H C; Ranitovic, P

    2015-10-23

    Ultrafast high harmonic beams provide new opportunities for coherently controlling excitation and ionization processes in atoms, molecules, and materials on attosecond time scales by employing multiphoton two-pathway electron-wave-packet quantum interferences. Here we use spectrally tailored and frequency tuned vacuum and extreme ultraviolet harmonic combs, together with two phase-locked infrared laser fields, to show how the total single and double photoionization yields of argon can be coherently modulated by controlling the relative phases of both optical and electronic-wave-packet quantum interferences. This Letter is the first to apply quantum control techniques to double photoionization, which is a fundamental process where a single, high-energy photon ionizes two electrons simultaneously from an atom. PMID:26551112

  2. Dynamic resonances and tunnelling in the multiphoton ionization of argon

    International Nuclear Information System (INIS)

    We present results of wavepacket simulations for multiphoton ionization in argon. A single active electron model is applied to estimate the single-electron ionization rates and photoelectron energy distributions for λ = 390 nm light with intensities up to I = 2 x 1014 W cm-2. The multiphoton ionization rates are compared with R-matrix Floquet calculations and found to be in very good agreement. The photoelectron energy distribution is used to study the nature of ionization at the higher intensities. Our results are consistent with recent calculations and experiments which show the imprint of the tunnelling process in the multiphoton regime. For few-cycle intense pulses, we find that the strong modulation of intensity and increased bandwidth leads to dynamic mixing of the 3d and 5s resonances.

  3. The ATLAS liquid Argon calorimeters read-out system

    CERN Document Server

    Blondel, A; Fayard, L; La Marra, D; Léger, A; Matricon, P; Perrot, G; Poggioli, L; Prast, J; Riu, I; Simion, S

    2004-01-01

    The calorimetry of the ATLAS experiment takes advantage of different detectors based on the liquid Argon (LAr) technology. Signals from the LAr calorimeters are processed by various stages before being delivered to the Data Acquisition system. The calorimeter cell signals are received by the front-end boards, which digitize a predetermined number of samples of the bipolar waveform and sends them to the Read-Out Driver (ROD) boards. The ROD board receives triggered data from 1028 calorimeter cells, and determines the precise energy and timing of the signals by processing the discrete samplings of the pulse. In addition, it formats the digital stream for the following elements of the DAQ chain, and performs monitoring. The architecture and functionality of the ATLAS LAr ROD board are discussed, along with the final design of the Processing Unit boards housing the Digital Signal Processors (DSP). (9 refs).

  4. Electron-ion recombination study in argon at atmospheric pressure

    International Nuclear Information System (INIS)

    This study deals with a wall-stabilized arc burning in argon at atmospheric pressure. A transient mode is obtained using a fast thyristor connected to the electrodes, which short-circuits the discharge. By means of two wavelengths laser interferometry and spectroscopy measurements we have determined the temporal changes of the electron density, ground state atom density and excited atom density. We have shown that, when the electric field is suppressed, the electron temperature rapidly decreases to the gas temperature before changing electron and atom densities. This phenomenon is applied to determine the gas temperature and to evaluate the role played by ionization in electron density balance. The coefficients of ambipolar diffusion, ionization and recombination and an apparent recombination coefficient are determined versus electron temperature and compared with theoretical values

  5. Atmospheric dispersion of argon-41 from anuclear research reactor: measurement and modeling of plume geometry and gamma radiation field

    DEFF Research Database (Denmark)

    Lauritzen, Bent; Astrup, Poul; Drews, Martin;

    2003-01-01

    An atmospheric dispersion experiment was conducted using a visible tracer along with the routine release of argon-41 from the BR1 research reactor in Mol, Belgium. Simultaneous measurements of plume geometry and radiation fields for argon-41 decay were performed as well as measurements of the argon...

  6. Investigations of the structural stability of metal hydride composites by in-situ neutron imaging

    Science.gov (United States)

    Herbrig, Kai; Pohlmann, Carsten; Gondek, Łukasz; Figiel, Henryk; Kardjilov, Nikolay; Hilger, André; Manke, Ingo; Banhart, John; Kieback, Bernd; Röntzsch, Lars

    2015-10-01

    Metal hydride composites (MHC) with expanded natural graphite (ENG) exhibiting enhanced thermal conductivity and reduced porosity compared to metal hydride powders can enable a reversible, compact and safe way for hydrogen storage. In this study, neutron imaging during cyclic hydrogenation was utilized to investigate the structural stability and the spatial-temporal hydrogen concentration of application-oriented MHC with 40 mm in diameter compared to a loose metal hydride powder. In particular, swelling and shrinking effects of a radially confined MHC which could freely expand upwards were studied. It was found that the loose powder bed was easily torn apart during dehydrogenation, which leads to increased thermal resistance within the hydride bed. In contrast, the thermal resistance between MHC and container wall was minimized since the initial gap closes during initial hydrogenation and does not reopen thereafter. Further cyclic hydrogenation caused MHC volume changes, i.e. an almost reversible swelling/shrinking (so-called "MHC breathing"). Moreover, neutron imaging allowed for the observation of reaction fronts within the MHC and the powder bed that are governed by the heat transfer.

  7. Synthesis and Characterization of Metal Hydride/Carbon Aerogel Composites for Hydrogen Storage

    Directory of Open Access Journals (Sweden)

    Kuen-Song Lin

    2012-01-01

    Full Text Available Two materials currently of interest for onboard lightweight hydrogen storage applications are sodium aluminum hydride (NaAlH4, a complex metal hydride, and carbon aerogels (CAs, a light porous material connected by several spherical nanoparticles. The objectives of the present work have been to investigate the synthesis, characterization, and hydrogenation behavior of Pd-, Ti- or Fe-doped CAs, NaAlH4, and MgH2 nanocomposites. The diameters of Pd nanoparticles onto CA’s surface and BET surface area of CAs were 3–10 nm and 700–900 m2g−1, respectively. The H2 storage capacity of metal hydrides has been studied using high-pressure TGA microbalance and they were 4.0, 2.7, 2.1, and 1.2 wt% for MgH2-FeTi-CAs, MgH2-FeTi, CAs-Pd, and 8 mol% Ti-doped NaAlH4, respectively, at room temperature. Carbon aerogels with higher surface area and mesoporous structures facilitated hydrogen diffusion and adsorption, which accounted for its extraordinary hydrogen storage phenomenon. The hydrogen adsorption abilities of CAs notably increased after inclusion of metal hydrides by the “hydrogen spillover” mechanisms.

  8. Herschel/HIFI detections of hydrides towards AFGL 2591: Envelope emission versus tenuous cloud absorption

    NARCIS (Netherlands)

    S. Bruderer; A.O. Benz; E.F. van Dishoeck; M. Melchior; S.D. Doty; F. van der Tak; P. Stäuber; S.F. Wampfler; C. Dedes; U.A. Yıldız; L. Pagani; T. Giannini; T. de Graauw; N. Whyborn; D. Teyssier; W. Jellema; R. Shipman; R. Schieder; N. Honingh; E. Caux; W. Bächtold; A. Csillaghy; C. Monstein; R. Bachiller; A. Baudry; M. Benedettini; E. Bergin; P. Bjerkeli; G.A. Blake; S. Bontemps; J. Braine; P. Caselli; J. Cernicharo; C. Codella; F. Daniel; A.M. Di Giorgio; C. Dominik; P. Encrenaz; M. Fich; A. Fuente; J.R. Goicoechea; F. Helmich; G.J. Herczeg; F. Herpin; M.R. Hogerheijde; T. Jacq; D. Johnstone; J.K. Jørgensen; L.E. Kristensen; B. Larsson; D. Lis; R. Liseau; M. Marseille; C. McCoey; G. Melnick; D. Neufeld; B. Nisini; M. Olberg; B. Parise; J.C. Pearson; R. Plume; C. Risacher; J. Santiago-García; P. Saraceno; R. Shipman; M. Tafalla; T.A. van Kempen; R. Visser; F. Wyrowski

    2010-01-01

    The Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory allows the first observations of light diatomic molecules at high spectral resolution and in multiple transitions. Here, we report deep integrations using HIFI in different lines of hydrides towards the high

  9. Herschel/HIFI detections of hydrides towards AFGL 2591. Envelope emission versus tenuous cloud absorption

    DEFF Research Database (Denmark)

    Bruderer, S.; Benz, A. O.; van Dishoeck, E. F.;

    2010-01-01

    The Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory allows the first observations of light diatomic molecules at high spectral resolution and in multiple transitions. Here, we report deep integrations using HIFI in different lines of hydrides towards the h...

  10. Thermal coupling of a high temperature PEM fuel cell with a complex hydride tank

    DEFF Research Database (Denmark)

    Pfeifer, P.; Wall, C.; Jensen, Jens Oluf;

    2009-01-01

    the possibilities of a thermal coupling of a high temperature PEM fuel cell operating at 160-200 degrees C. The starting temperatures and temperature hold-times before starting fuel cell operation, the heat transfer characteristics of the hydride storage tanks, system temperature, fuel cell electrical power...

  11. Aluminum-titanium hydride-boron carbide composite provides lightweight neutron shield material

    Science.gov (United States)

    Poindexter, A. M.

    1967-01-01

    Inexpensive lightweight neutron shield material has high strength and ductility and withstands high internal heat generation rates without excessive thermal stress. This composite material combines structural and thermal properties of aluminum, neutron moderating properties of titanium hydride, and neutron absorbing characteristics of boron carbide.

  12. The influence of stress state on the reorientation of hydrides in a zirconium alloy

    Science.gov (United States)

    Cinbiz, Mahmut N.; Koss, Donald A.; Motta, Arthur T.

    2016-08-01

    Hydride reorientation can occur in spent nuclear fuel cladding when subjected to a tensile hoop stress above a threshold value during cooling. Because in these circumstances the cladding is under a multiaxial stress state, the effect of stress biaxiality on the threshold stress for hydride reorientation is investigated using hydrided CWSR Zircaloy-4 sheet specimens containing ∼180 wt ppm of hydrogen and subjected to a two-cycle thermo-mechanical treatment. The study is based on especially designed specimens within which the stress biaxiality ratios range from uniaxial (σ2/σ1 = 0) to "near-equibiaxial" tension (σ2/σ1 = 0.8). The threshold stress is determined by mapping finite element calculations of the principal stresses and of the stress biaxiality ratio onto the hydride microstructure obtained after the thermo-mechanical treatment. The results show that the threshold stress (maximum principal stress) decreases from 155 to 75 MPa as the stress biaxiality increases from uniaxial to "near-equibiaxial" tension.

  13. A PROTOTYPE FOUR INCH SHORT HYDRIDE (FISH) BED AS A REPLACEMENT TRITIUM STORAGE BED

    Energy Technology Data Exchange (ETDEWEB)

    Klein, J.; Estochen, E.; Shanahan, K.; Heung, L.

    2011-02-23

    The Savannah River Site (SRS) tritium facilities have used 1st generation (Gen1) metal hydride storage bed assemblies with process vessels (PVs) fabricated from 3 inch nominal pipe size (NPS) pipe to hold up to 12.6 kg of LaNi{sub 4.25}Al{sub 0.75} metal hydride for tritium gas absorption, storage, and desorption for over 15 years. The 2nd generation (Gen2) of the bed design used the same NPS for the PV, but the added internal components produced a bed nominally 1.2 m long, and presented a significant challenge for heater cartridge replacement in a footprint limited glove-box. A prototype 3rd generation (Gen3) metal hydride storage bed has been designed and fabricated as a replacement candidate for the Gen2 storage bed. The prototype Gen3 bed uses a PV pipe diameter of 4 inch NPS so the bed length can be reduced below 0.7 m to facilitate heater cartridge replacement. For the Gen3 prototype bed, modeling results show increased absorption rates when using hydrides with lower absorption pressures. To improve absorption performance compared to the Gen2 beds, a LaNi{sub 4.15}Al{sub 0.85} material was procured and processed to obtain the desired pressure-composition-temperature (PCT) properties. Other bed design improvements are also presented.

  14. First Principles Studies of Phase Stability and Reaction Dynamics in Complex Metal Hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Mei-Yin

    2014-09-29

    Complex metal hydrides are believed to be one of the most promising materials for developing hydrogen storage systems that can operate under desirable conditions. At the same time, these are also a class of materials that exhibit intriguing properties. We have used state-of-the-art computational techniques to study the fundamental properties of these materials.

  15. The impact of carbon materials on the hydrogen storage properties of light metal hydrides

    NARCIS (Netherlands)

    Adelhelm, P.A.; de Jongh, P.E.

    2011-01-01

    The safe and efficient storage of hydrogen is still one of the remaining challenges towards fuel cell powered cars. Metal hydrides are a promising class of materials as they allow the storage of large amounts of hydrogen in a small volume at room temperature and low pressures. However, usually the k

  16. Application of thermal electrochemical equation to metal-hydride half-cell system

    Institute of Scientific and Technical Information of China (English)

    LIU Kai-yu; HUANG Bai-yun; ZHANG Ping-min; HE Yue-hui; ZHOU Ke-chao; SU Geng

    2006-01-01

    Application of thermal electrochemical equation to metal-hydride half-cell system was investigated, and the influence of state of charge on the thermal electrochemical performance of hydrogen storage materials was studied. The results show that both the absolute value of the molar enthalpy change and the internal resistance of evolution hydrogen reaction are less than that of absorption hydrogen reaction at the same state of charge. The molar reaction enthalpy change of absorption and evolution of hydride electrode change contrarily with the enhancement of filling degree of hydrogen in hydride electrode. The relation curve of molar reaction enthalpy change to state of charge, both absorption and evolution hydrogen reaction, is close to a constant when the state of charge is 10%-60%, and during state of charge below 10% or state of charge above 60%, the molar reaction enthalpy change varies sharply. Meanwhile, the internal resistance of electrode reaction has an ascending trend with the enhancement on filling degree of hydrogen in hydride electrode in both absorption and evolution hydrogen reaction.

  17. Non-Precious Bimetallic Catalysts for Selective Dehydrogenation of an Organic Chemical Hydride System

    KAUST Repository

    Shaikh Ali, Anaam

    2015-07-06

    Methylcyclohexane (MCH)-Toluene (TOL) chemical hydride cycles as a hydrogen carrier system is successful with the selective dehydrogenation reaction of MCH to TOL, which has been achieved only using precious Pt-based catalysts. Herein, we report improved selectivity using non-precious metal nickel-based bimetallic catalysts, where the second metal occupies the unselective step sites.

  18. Internal hydriding in irradiated defected Zircaloy fuel rods: A review (LWBR Development Program)

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, J C

    1987-10-01

    Although not a problem in recent commercial power reactors, including the Shippingport Light Water Breeder Reactor, internal hydriding of Zircaloy cladding was a persistent cause of gross cladding failures during the 1960s. It occurred in the fuel rods of water-cooled nuclear power reactors that had a small cladding defect. This report summarizes the experimental findings, causes, mechanisms, and methods of minimizing internal hydriding in defected Zircaloy-clad fuel rods. Irradiation test data on the different types of defected fuel rods, intentionally fabricated defected and in-pile operationally defected rods, are compared. Significant factors affecting internal hydriding in defected Zircaloy-clad fuel rods (defect hole size, internal and external sources of hydrogen, Zircaloy cladding surface properties, nickel alloy contamination of Zircaloy, the effect of heat flux and fluence) are discussed. Pertinent in-pile and out-of-pile test results from Bettis and other laboratories are used as a data base in constructing a qualitative model which explains hydrogen generation and distribution in Zircaloy cladding of defected water-cooled reactor fuel rods. Techniques for minimizing internal hydride failures in Zircaloy-clad fuel rods are evaluated.

  19. Titanium compacts produced by the pulvimetallurgical hydride-dehydride method for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Barreiro, M M [Materiales Dentales, Facultad de OdontologIa, Universidad de Buenos Aires, Marcelo T de Alvear 2142 (1122), Buenos Aires (Argentina); Grana, D R; Kokubu, G A [PatologIa I. Escuela de OdontologIa, Facultad de Medicina. Asociacion Odontologica Argentina-Universidad del Salvador, Tucuman 1845 (1050) Buenos Aires (Argentina); Luppo, M I; Mintzer, S; Vigna, G, E-mail: mbarreiro@mater.odon.uba.a, E-mail: dgrana@usal.edu.a, E-mail: luppo@cnea.gov.a, E-mail: vigna@cnea.gov.a [Departamento Materiales, Comision Nacional de Energia Atomica, Gral Paz 1499 (B1650KNA), San MartIn, Buenos Aires (Argentina)

    2010-04-15

    Titanium powder production by the hydride-dehydride method has been developed as a non-expensive process. In this work, commercially pure grade two Ti specimens were hydrogenated. The hydrided material was milled in a planetary mill. The hydrided titanium powder was dehydrided and then sieved to obtain a particle size between 37 and 125{mu}m in order to compare it with a commercial powder produced by chemical reduction with a particle size lower than 150{mu}m. Cylindrical green compacts were obtained by uniaxial pressing of the powders at 343 MPa and sintering in vacuum. The powders and the density of sintered compacts were characterized, the oxygen content was measured and in vivo tests were performed in the tibia bones of Wistar rats in order to evaluate their biocompatibility. No differences were observed between the materials which were produced either with powders obtained by the hydride-dehydride method or with commercial powders produced by chemical reduction regarding modifications in compactation, sintering and biological behaviour.

  20. Internal hydriding in irradiated defected Zircaloy fuel rods: A review (LWBR Development Program)

    International Nuclear Information System (INIS)

    Although not a problem in recent commercial power reactors, including the Shippingport Light Water Breeder Reactor, internal hydriding of Zircaloy cladding was a persistent cause of gross cladding failures during the 1960s. It occurred in the fuel rods of water-cooled nuclear power reactors that had a small cladding defect. This report summarizes the experimental findings, causes, mechanisms, and methods of minimizing internal hydriding in defected Zircaloy-clad fuel rods. Irradiation test data on the different types of defected fuel rods, intentionally fabricated defected and in-pile operationally defected rods, are compared. Significant factors affecting internal hydriding in defected Zircaloy-clad fuel rods (defect hole size, internal and external sources of hydrogen, Zircaloy cladding surface properties, nickel alloy contamination of Zircaloy, the effect of heat flux and fluence) are discussed. Pertinent in-pile and out-of-pile test results from Bettis and other laboratories are used as a data base in constructing a qualitative model which explains hydrogen generation and distribution in Zircaloy cladding of defected water-cooled reactor fuel rods. Techniques for minimizing internal hydride failures in Zircaloy-clad fuel rods are evaluated

  1. Catalyzed light hydride nanomaterials embedded in a micro-channels hydrogen storage container.

    Science.gov (United States)

    Dehouche, Zahir; Peretti, Hernán A; Yoo, Yeong; Belkacemi, Khaled; Goyette, Jacques

    2009-01-01

    Activated alloys synthesized by arc-melting were examined as catalysts for improving the hydrogen sorption characteristics of nanostructured magnesium hydride, proposed as a reversible hydrogen storage material. The MgH(2)-catalyst absorbing materials were prepared by ball milling of pure MgH(2) with hydrided Zr(47)Ni(53), Zr(9)Ni(11), and other alloys investigated. The nanostructured MgH(2)-intermetallic systems were tested at 250 degrees C and catalyst addition of eutectoid Zr(47)Ni(53) resulted in the fastest desorption time and highest initial desorption rate. The catalyzed Mg-hydride with activated Zr(9)Ni(11) and Zr(7)Ni(10) phases showed fast desorption kinetics. Moreover, the results demonstrated that the composition of dispersed Zr(x)Ni(y)catalysts has a strong influence on the amount of accumulated hydrogen and desorption rate of Mg-nanocomposite. Part two covers advanced micro-channels hydrogen storage module design based on the results of semi-empirical computer simulations of heat and mass transfers in the container. The micro-channels reservoir concept offers many advantages over the conventional metal hydride hydrogen storage system. It is a micro-structured system that can pack a lot of power into a small space and dissipate effectively the heat of the sorption reactions. This review summarizes recent patents related to CNTS.

  2. Titanium compacts produced by the pulvimetallurgical hydride-dehydride method for biomedical applications

    International Nuclear Information System (INIS)

    Titanium powder production by the hydride-dehydride method has been developed as a non-expensive process. In this work, commercially pure grade two Ti specimens were hydrogenated. The hydrided material was milled in a planetary mill. The hydrided titanium powder was dehydrided and then sieved to obtain a particle size between 37 and 125 μm in order to compare it with a commercial powder produced by chemical reduction with a particle size lower than 150 μm. Cylindrical green compacts were obtained by uniaxial pressing of the powders at 343 MPa and sintering in vacuum. The powders and the density of sintered compacts were characterized, the oxygen content was measured and in vivo tests were performed in the tibia bones of Wistar rats in order to evaluate their biocompatibility. No differences were observed between the materials which were produced either with powders obtained by the hydride-dehydride method or with commercial powders produced by chemical reduction regarding modifications in compactation, sintering and biological behaviour.

  3. Hydride reduction of B-norcholestane 5a,6a-epoxide

    Directory of Open Access Journals (Sweden)

    LJUBINKA B. LORENC

    2002-01-01

    Full Text Available B-Norcholestane epoxide 2 is reduced with lithium aluminium hydride to give either the 3b,6a-diol 3 or the corresponding 3b,5a-diol 4, depending on the quality of the reducing reagent employed. A plausible mechanistic explanation of the obtained results is suggested.

  4. Molecular early main group metal hydrides : synthetic challenge, structures and applications

    NARCIS (Netherlands)

    Harder, Sjoerd

    2012-01-01

    Within the general area of early main group metal chemistry, the controlled synthesis of well-defined metal hydride complexes is a rapidly developing research field. As group 1 and 2 metal complexes are generally highly dynamic and lattice energies for their [MH](infinity) and [MH2](infinity) salts

  5. Argon Kα measurement on DIII endash D by Ross filters technique (abstract)

    International Nuclear Information System (INIS)

    Techniques to reduce the heat flux to the divertor plates in tokamak power plants and the consequent erosion of, and subsequent damage to the divertor target plates include the injection of impurities such as argon, that can dissipate the energy (through radiative or collisional processes) before it reaches the target plates. An important issue with this type of scheme is poisoning of the plasma core by the impurities introduced in the divertor region. Subsequently, there is a desire to measure the profiles of the injected impurities in the core. X-ray Ross filters with an effective narrow band pass centered on the argon Kα line at 3.2 keV, have been installed on two of the existing x-ray arrays on DIII endash D in order to help determine the argon concentration profiles. Emissivity profiles of the Kα lines and the emissivity profiles for the argon enhanced continuum can be inferred from the inverted filtered x-ray brightness signals if Te, ne, and Ar18+ profiles are known. The MIST code is used to couple the filtered x-ray signals to the time dependent measurements of Te and ne. Further, the Ar16+ profiles measured by charge transfer spectroscopy, are used as a constraint on the MIST code runs to calculate Ar18+ profiles and unfold the argon emissivity profiles. A discussion of the Ross filters, the DIII endash D argon data, and the data analysis scheme for inferring argon emissivity profiles will be discussed. Estimates of the total argon concentration in the core determined from this technique in DIII endash D argon puff experiments will be presented. copyright 1999 American Institute of Physics

  6. Wetting and evaporation of argon nanodroplets on smooth and rough substrates: Molecular dynamics simulations

    Science.gov (United States)

    Li, Qun; Wang, Baohe; Chen, Yonggang; Zhao, Zongchang

    2016-10-01

    Wetting and evaporation behaviors of argon nanodroplets on smooth and rough substrates are studied using molecular dynamics simulations. Effects of interaction energy between solid and argon atoms on wetting and evaporation and differences between nanodroplets on smooth and rough substrates have been investigated. The results show that for both smooth and rough substrates, as the interaction energy between solid and argon atoms increases, the contact angle and total evaporation increase. For rough substrates, the variations of contact angle and contact radius during evaporation progress are much more complex and the total evaporation is much larger than that of smooth substrates.

  7. A Study of Dielectric Breakdown Along Insulators Surrounding Conductors in Liquid Argon

    CERN Document Server

    Lockwitz, Sarah

    2015-01-01

    High voltage breakdown in liquid argon is an important consideration in the design of liquid argon time projection chambers, which are often used as neutrino and dark matter detectors. We have made systematic measurements of breakdown voltages in liquid argon along insulators surrounding negative rod electrodes. The purpose of these tests is to understand the effects of materials, of breakdown path length, and of surface topology. We have found no material-specific effects other than those due to their permittivity. We have found no dependence on breakdown voltage on the length of the exposed insulator. A model for the breakdown mechanism is presented that can help inform future designs.

  8. Design Principles and Operational Results of the Cryogenic System for the ATLAS Liquid Argon Calorimeter

    CERN Document Server

    Fabre, C; Chalifour, M; Gonidec, G; Passardi, Giorgio; Petit, P; Pezzetti, M; Wicek, F

    2009-01-01

    The ATLAS liquid argon calorimeter housed in three independent cryostats containing a total argon volume of about 78 m3 has been installed in the underground cavern. The three detectors have been cooled down following stringent temperature gradient limits and have been filled with liquid argon. The cryostats are now in a stable condition for periods going up to almost two years. The temperature uniformity within each of the three detector volumes is found to be within 70 mK rms, while the temperature stability stays below 5 mK rms.

  9. A new ozone standard - The vapor pressure of ozone at liquid argon temperatures

    Science.gov (United States)

    Mauersberger, K.; Hanson, D.; Morton, J.

    1985-01-01

    The vapor pressure of ozone has been measured at liquid argon temperatures. At the normal boiling point of argon (-185.9 C) an ozone pressure of 0.0405 torr was obtained with an accuracy of + or - 1.5 percent. Increases and decreases in liquid argon temperatures raised and lowered the ozone vapor pressure, respectively. During the vapor pressure measurements the purity of ozone was monitored with a mass spectrometer. The proposed ozone standard will considerably improve the calibration of experiments for atmospheric research, the determination of absorption cross sections and other laboratory ozone studies.

  10. Surface compositional changes in GaAs subjected to argon plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Surdu-Bob, C.C.; Sullivan, J.L.; Saied, S.O.; Layberry, R.; Aflori, M

    2002-12-30

    X-ray photoelectron spectroscopy (XPS) has been employed to study surface compositional changes in GaAs (1 0 0) subjected to argon plasma treatment. The experimental results have been explained in terms of predicted argon ion energies, measured ion densities and etch rates. A model is proposed for the processes taking place at the surface of GaAs in terms of segregation, sputtering and surface relaxation. Stopping and range of ions in matter (SRIM) code has also been employedan aid to identification of the mechanisms responsible for the compositional changes. Argon plasma treatment induced surface oxidation at very low energies and sputtering and surface damage with increasing energy.

  11. Changes in a surface of polycrystalline aluminum upon bombardment with argon ions

    Science.gov (United States)

    Ashkhotov, O. G.; Ashkhotova, I. B.; Bliev, A. P.; Magkoev, T. T.; Krymshokalova, D. A.

    2014-10-01

    The interaction between argon ions and a natural oxide layer of polycrystalline aluminum is studied via Auger electron (AE) and electron energy loss (EEL) spectroscopy. It is found that bombardment with argon ions whose energy is lower than the Al2O3 sputtering threshold results in the accumulation of bombarding ions in interstitial surface voids, thus forming a supersaturated solid solution of target atoms and bombarding ions of argon and nitrogen entrapped by the ion beam from the residual gas of the working chamber of the spectrometer.

  12. Reproduction in laboratory of the morphology distribution and orientation of hydrides in different stages fuel cycle; Reproduccion en laboratorio de la morfologia, distribucion y orientacion de hidruros en distintas etapas del ciclo de combustible

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Rengel, M. A.; Gomez, F. J.; Ruiz-Hervias, J.

    2013-07-01

    In this paper, the experimental techniques employed to reproduce in the laboratory the distribution, morphology and orientation of the hydrides during the different steps of the nuclear fuel cycle are reported. A cathodic charging technique was employed to produce ZIRLO cladding samples with an homogeneous distribution of hydrides and concentrations of 150, 250, 500, 1200 and 2000 ppm of hydrogen. The treatments developed to produce radial hydride reorientation, hydride blisters and a peripheral rim of hydrides are described.

  13. Application of hafnium hydride control rod to large sodium cooled fast breeder reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Kazumi, E-mail: kazumi_ikeda@mfbr.mhi.co.jp [Mitsubishi FBR Systems, Inc., 34-17, Jingumae 2-Chome, Shibuya-ku, Tokyo 150-0001 (Japan); Moriwaki, Hiroyuki, E-mail: hiroyuki_moriwaki@mfbr.mhi.co.jp [Mitsubishi FBR Systems, Inc., 34-17, Jingumae 2-Chome, Shibuya-ku, Tokyo 150-0001 (Japan); Ohkubo, Yoshiyuki, E-mail: yoshiyuki_okubo@mfbr.mhi.co.jp [Mitsubishi FBR Systems, Inc., 34-17, Jingumae 2-Chome, Shibuya-ku, Tokyo 150-0001 (Japan); Iwasaki, Tomohiko, E-mail: tomohiko.iwasaki@qse.tohoku.ac.jp [Department of Quantum Science and Energy Engineering, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai-shi, Miyagi-ken 980-8579 (Japan); Konashi, Kenji, E-mail: konashi@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, Narita-cho, Oarai-machi, Higashi-Ibaraki-gun, Ibaraki-ken 311-1313 (Japan)

    2014-10-15

    Highlights: • Application of hafnium hydride control rod to large sodium cooled fast breeder reactor. • This paper treats application of an innovative hafnium hydride control rod to a large sodium cooled fast breeder reactor. • Hydrogen absorption triples the reactivity worth by neutron spectrum shift at H/Hf ratio of 1.3. • Lifetime of the control rod quadruples because produced daughters of hafnium isotopes are absorbers. • Nuclear and thermal hydraulic characteristics of the reactor are as good as or better than B-10 enriched boron carbide. - Abstract: This study treats the feasibility of long-lived hafnium hydride control rod in a large sodium-cooled fast breeder reactor by nuclear and thermal analyses. According to the nuclear calculations, it is found that hydrogen absorption of hafnium triples the reactivity by the neutron spectrum shift at the H/Hf ratio of 1.3, and a hafnium transmutation mechanism that produced daughters are absorbers quadruples the lifetime due to a low incineration rate of absorbing nuclides under irradiation. That is to say, the control rod can function well for a long time because an irradiation of 2400 EFPD reduces the reactivity by only 4%. The calculation also reveals that the hafnium hydride control rod can apply to the reactor in that nuclear and thermal characteristics become as good as or better than 80% B-10 enriched boron carbide. For example, the maximum linear heat rate becomes 3% lower. Owing to the better power distribution, the required flow rate decreases approximately by 1%. Consequently, it is concluded on desk analyses that the long lived hafnium hydride control rod is feasible in the large sodium-cooled fast breeder reactor.

  14. Advanced chemical hydride-based hydrogen generation/storage system for fuel cell vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Breault, R.W.; Rolfe, J. [Thermo Power Corp., Waltham, MA (United States)

    1998-08-01

    Because of the inherent advantages of high efficiency, environmental acceptability, and high modularity, fuel cells are potentially attractive power supplies. Worldwide concerns over clean environments have revitalized research efforts on developing fuel cell vehicles (FCV). As a result of intensive research efforts, most of the subsystem technology for FCV`s are currently well established. These include: high power density PEM fuel cells, control systems, thermal management technology, and secondary power sources for hybrid operation. For mobile applications, however, supply of hydrogen or fuel for fuel cell operation poses a significant logistic problem. To supply high purity hydrogen for FCV operation, Thermo Power`s Advanced Technology Group is developing an advanced hydrogen storage technology. In this approach, a metal hydride/organic slurry is used as the hydrogen carrier and storage media. At the point of use, high purity hydrogen will be produced by reacting the metal hydride/organic slurry with water. In addition, Thermo Power has conceived the paths for recovery and regeneration of the spent hydride (practically metal hydroxide). The fluid-like nature of the spent hydride/organic slurry will provide a unique opportunity for pumping, transporting, and storing these materials. The final product of the program will be a user-friendly and relatively high energy storage density hydrogen supply system for fuel cell operation. In addition, the spent hydride can relatively easily be collected at the pumping station and regenerated utilizing renewable sources, such as biomass, natural, or coal, at the central processing plants. Therefore, the entire process will be economically favorable and environmentally friendly.

  15. Calculation of thermodynamic hydricities and the design of hydride donors for CO2 reduction

    Science.gov (United States)

    Muckerman, James T.; Achord, Patrick; Creutz, Carol; Polyansky, Dmitry E.; Fujita, Etsuko

    2012-01-01

    We have developed a correlation between experimental and density functional theory-derived results of the hydride-donating power, or “hydricity”, of various ruthenium, rhenium, and organic hydride donors. This approach utilizes the correlation between experimental hydricity values and their corresponding calculated free-energy differences between the hydride donors and their conjugate acceptors in acetonitrile, and leads to an extrapolated value of the absolute free energy of the hydride ion without the necessity to calculate it directly. We then use this correlation to predict, from density functional theory-calculated data, hydricity values of ruthenium and rhenium complexes that incorporate the pbnHH ligand—pbnHH = 1,5-dihydro-2-(2-pyridyl)-benzo[b]-1,5-naphthyridine—to model the function of NADPH. These visible light-generated, photocatalytic complexes produced by disproportionation of a protonated-photoreduced dimer of a metal-pbn complex may be valuable for use in reducing CO2 to fuels such as methanol. The excited-state lifetime of photoexcited [Ru(bpy)2(pbnHH)]2+ is found to be about 70 ns, and this excited state can be reductively quenched by triethylamine or 1,4-diazabicyclo[2.2.2]octane to produce the one-electron-reduced [Ru(bpy)2(pbnHH)]+ species with half-life exceeding 50 μs, thus opening the door to new opportunities for hydride-transfer reactions leading to CO2 reduction by producing a species with much increased hydricity. PMID:22826261

  16. The hydride anion in an extended transition metal oxide array: LaSrCoO3H0.7.

    Science.gov (United States)

    Hayward, M A; Cussen, E J; Claridge, J B; Bieringer, M; Rosseinsky, M J; Kiely, C J; Blundell, S J; Marshall, I M; Pratt, F L

    2002-03-01

    We present the synthesis and structural characterization of a transition metal oxide hydride, LaSrCoO3H0.7, which adopts an unprecedented structure in which oxide chains are bridged by hydride anions to form a two-dimensional extended network. The metal centers are strongly coupled by their bonding with both oxide and hydride ligands to produce magnetic ordering at temperatures up to at least 350 kelvin. The synthetic route is sufficiently general to allow the prediction of a new class of transition metal--containing electronic and magnetic materials. PMID:11884751

  17. Self-assembled heterogeneous argon/neon core-shell clusters studied by photoelectron spectroscopy.

    Science.gov (United States)

    Lundwall, M; Pokapanich, W; Bergersen, H; Lindblad, A; Rander, T; Ohrwall, G; Tchaplyguine, M; Barth, S; Hergenhahn, U; Svensson, S; Björneholm, O

    2007-06-01

    Clusters formed by a coexpansion process of argon and neon have been studied using synchrotron radiation. Electrons from interatomic Coulombic decay as well as ultraviolet and x-ray photoelectron spectroscopy were used to determine the heterogeneous nature of the clusters and the cluster structure. Binary clusters of argon and neon produced by coexpansion are shown to exhibit a core-shell structure placing argon in the core and neon in the outer shells. Furthermore, the authors show that 2 ML of neon on the argon core is sufficient for neon valence band formation resembling the neon solid. For 1 ML of neon the authors observe a bandwidth narrowing to about half of the bulk value.

  18. Surface Chemistry of Polymers Physical Adsorption of Nitrogen, Argon, Sulfur Dioxide and Neopentane on Polyvinylidene Fluoride

    OpenAIRE

    Houriet, Jean-Philippe; Ghiste, Patrick; Stoeckli, Fritz

    2007-01-01

    The adsorption of nitrogen, argon, sulfur dioxide and neopentane on polyvinylidene fluoride has been measured by static methods and by gas-solid chromatography. The polymer has a homogeneous surface of low energy, which is not significantly affected by heating.

  19. Surface modification of polypropylene using argon plasma: Statistical optimization of the process variables

    International Nuclear Information System (INIS)

    Low pressure plasma treatment using radiofrequency (rf) discharge of argon gas was employed to improve the hydrophilicity of polypropylene. The effects of argon plasma on the wettability, surface chemistry and surface morphology of polypropylene were studied using static contact angle measurements, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Increase in surface energy of polypropylene was observed as a result of argon plasma treatment. SEM and AFM images revealed the increased surface roughness. A set of identified process variables (rf power, pressure, argon flow rate and time) were used in this study and were optimized using central composite design (CCD) of response surface methodology (RSM). A statistical model was developed to represent the surface energy in terms of the process variables mentioned above. Accuracy of the model was verified and found to be high.

  20. Simulations of argon accident scenarios in the ATLAS experimental cavern a safety analysis

    CERN Document Server

    Balda, F

    2002-01-01

    Some characteristic accidents in the ATLAS experimental cavern (UX15) are simulated by means of STAR-CD, a code using the "Finite-Volume" method. These accidents involve different liquid argon leaks from the barrel cryostat of the detector, thus causing the dispersion of the argon into the Muon Chamber region and the evaporation of the liquid. The subsequent temperature gradients and distribution of argon concentrations, as well as their evolution in time are simulated and discussed, with the purpose of analysing the dangers related to asphyxiation and to contact with cryogenic fluids for the working personnel. A summary of the theory that stands behind the code is also given. In order to validate the models, an experimental test on a liquid argon spill performed earlier is simulated, showing that the program is able to output reliable results. At the end, some safety-related recommendations are listed.

  1. Pose Measurement Performance of the Argon Relative Navigation Sensor Suite in Simulated Flight Conditions

    Science.gov (United States)

    Galante, Joseph M.; Eepoel, John Van; Strube, Matt; Gill, Nat; Gonzalez, Marcelo; Hyslop, Andrew; Patrick, Bryan

    2012-01-01

    Argon is a flight-ready sensor suite with two visual cameras, a flash LIDAR, an on- board flight computer, and associated electronics. Argon was designed to provide sensing capabilities for relative navigation during proximity, rendezvous, and docking operations between spacecraft. A rigorous ground test campaign assessed the performance capability of the Argon navigation suite to measure the relative pose of high-fidelity satellite mock-ups during a variety of simulated rendezvous and proximity maneuvers facilitated by robot manipulators in a variety of lighting conditions representative of the orbital environment. A brief description of the Argon suite and test setup are given as well as an analysis of the performance of the system in simulated proximity and rendezvous operations.

  2. Formation and characterization of magnesium bisozonide and carbonyl complexes in solid argon.

    Science.gov (United States)

    Wang, Guanjun; Gong, Yu; Zhang, Qingqing; Zhou, Mingfei

    2010-10-14

    The reactions of magnesium atoms with dioxygen and dioxygen/carbon monoxide mixture have been investigated by matrix isolation infrared absorption spectroscopy. Magnesium atoms react with dioxygen in solid argon to form the inserted MgO(2) molecules under UV excitation, which were previously characterized. Annealing allows the dioxygen molecules to diffuse and to react with MgO(2) and form the magnesium bisozonide complex, Mg(O(3))(2), which is proposed to be coordinated by two argon atoms in solid argon matrix. The Mg(O(3))(2)(Ar)(2) complex is characterized to have two equivalent side-on bonded ozonide ligands with a D(2h) symmetry. The coordinated argon atoms can be replaced by carbon monoxide to give the magnesium bisozonide dicarbonyl complex, Mg(O(3))(2)(CO)(2), a neutral magnesium carbonyl complex with CO binding to the Mg(2+) center. PMID:20857987

  3. Dynamic range compression in a liquid argon calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Cleland, W.E. [Univ. of Pittsburgh, PA (United States); Lissauer, D.; Radeka, V.; Rescia, S.; Takai, H. [Brookhaven National Lab., Upton, NY (United States); Wingerter-Seez, I. [LAPP, Annecy-le-Vieux (France)

    1996-12-31

    The anticipated range of particle energies at the LHC, coupled with the need for precision, low noise calorimetry makes severe demands on the dynamic range of the calorimeter readout. A common approach to this problem is to use shapers with two or more gain scales. In this paper, the authors describe their experience with a new approach in which a preamplifier with dynamic gain compression is used. An unavoidable consequence of dynamic gain adjustment is that the peaking time of the shaper output signal becomes amplitude dependent. The authors have carried out a test of such a readout system in the RD3 calorimeter, a liquid argon device with accordion geometry. The calibration system is used to determine both the gain of the individual channels as well as to map the shape of the waveform as a function of signal amplitude. A new procedure for waveform analysis, in which the fitted parameters describe the impulse response of the system, permits a straightforward translation of the calibration waveform to the waveform generated by a particle crossing the ionization gap. They find that the linearity and resolution of the calorimeter is equivalent to that obtained with linear preamplifiers, up to an energy of 200 GeV.

  4. Coherent set of electron cross sections for argon

    Science.gov (United States)

    Alves, L. L.; Ferreira, C. M.

    2011-10-01

    This paper presents a coherent set of electron impact cross sections for argon (elastic momentum-transfer, inelastic for the excitation of 37 levels Ar(4s,4p,3d,5p,4d,6s) and ionization), which was recently uploaded onto the LXcat IST-Lisbon database. The cross section set was validated by comparing calculated swarm parameters (electron mobility and characteristic energy) and rate coefficients (Townsend ionization coefficient and direct + cascade excitation coefficients to the 4s and 4p states) with available experimental data, for E / N = 10-4 - 100 Td and Tg = 300, 77 K. The validation procedure involves the solution to the homogeneous two-term electron Boltzmann equation, resorting to three different solvers: (i) IST-Lisbon's (ii) BOLSIG+ (v1.2) with LXcat; (iii) BOLSIG+ (v1.23). The results obtained with these solvers are compared to evidence the importance of certain numerical features related with both the energy-grid (number of points, grid-type and maximum energy value) and the interpolation scheme adopted for the cross sections. In particular, the latter can cause a 6% variation on the values of swarm parameters at intermediate E/Ns.

  5. An update of argon inelastic cross sections for plasma discharges

    International Nuclear Information System (INIS)

    This paper proposes a coherent set of electron impact inelastic cross sections for argon, based on recent experimental measurements. The updated set is validated by comparing calculated swarm parameters and rate coefficients (obtained by solving the two-term approximation electron Boltzmann equation) with available experimental data. This validation procedure is usually adopted when the cross section set is to be later used in plasma discharge modelling. Simulation results for the electron drift velocity and characteristic energy are in very good agreement with experimental values of these quantities. Calculations, using cross section sets proposed by different authors, of the total (direct + cascade) excitation coefficients to the 4s and 4p states, and of the Townsend ionization coefficient, show that the present set ensures the best overall agreement with measured values. The agreement is particularly good for the excitation coefficient to metastable 4s'[1/2]0 and the Townsend ionization coefficient, which are probably the most relevant electron macroscopic coefficients in the modelling of discharge plasmas

  6. Argon defect complexes in low energy Ar irradiated molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    van Veen, A.; Buters, W.T.M.; van der Kolk, G.J.; Caspers, L.M. (Interuniversitair Reactor Instituut, Delft (Netherlands)); Armstrong, T.R. (Victoria Univ., Wellington (New Zealand). Dept. of Physics)

    1982-03-15

    Thermal desorption spectrometry has been used to study the defects created in Mo irradiated along the <110> direction with Ar ions ranging in energy from 0.1 to 2 keV. In addition to monitoring the release of the implanted Ar, additional information has been obtained by decoration of the defects with low energy helium and subsequent monitoring of the helium release. The studies show evidence that the Ar can be trapped in both substitutional sites and in a configuration in which the Ar is associated with vacancies (ArVsub(n), n >= 2). Most of the Ar implanted at high energy is released at approx. equal to 1500 K by thermal vacancy assisted diffusion. Argon trapped closer to the surface is released at lower temperatures via at least three different surface related release mechanisms. Additional results are presented on the interaction of self interstitial atoms (introduced by 100 eV Xe bombardment) with the Ar defects. Substitutional Ar is found to convert to interstitial Ar which seems to be mobile at room temperature. The Ar-vacancy complexes are found to be reduced to substitutional Ar. The results of atomistic calculations of the release mechanisms will also be presented.

  7. Scintillation Light from Cosmic-Ray Muons in Liquid Argon

    CERN Document Server

    Whittington, Denver

    2014-01-01

    This paper reports the results of the first experiment to directly measure the properties of the scintillation light generated by minimum ionizing cosmic-ray muons in liquid argon. Scintillation light from these muons is of value to studies of weakly-interacting particles in neutrino experiments and dark matter searches, as well as for particle identification. The experiment was carried out at the TallBo facility at Fermilab using prototype light guides and electronics developed for the Long-Baseline Neutrino Experiment. Analysis of the time-resolved structure of the scintillation light from cosmic-ray muons gives $\\langle \\tau_{\\text{T}}\\rangle = 1.43 \\pm 0.04~\\text{(stat.)} \\pm 0.007~\\text{(sys.)}~\\mu$s for the triplet light decay time constant. The ratio of singlet to triplet light measured using surface-coated light guides is $R = 0.39 \\pm 0.01~\\text{(stat.)} \\pm 0.008~\\text{(sys.)}$. There is some evidence that this value is not consistent with $R$ for minimum ionizing electrons. However, the value for $...

  8. State-selective radiative recombination cross sections of argon ions

    International Nuclear Information System (INIS)

    The n-, (n,l)- and fine-structure level state-selective radiative recombinations (RR) cross sections of argon ions Ar18+,Ar13+,Ar7+ and Ar+ are obtained with the semi-classical Kramer formula, the relativistic self-consistent field (RSCF) method and the relativistic configuration interaction (RCI) method. It is found that for the highly charged ions with few electrons, the cross sections calculated with these three methods are in good agreement with each other. But as the number of electrons increases, the Kramer formula deviates from the RSCF and RCI results. For instance, when the energy of the incident electron is larger than 100 eV, the n-state selective cross sections of Ar7+ calculated from the Kramer formula are underestimated for more than 50%. The RSCF results are in general agreement with the RCI results. However, for the low charged ions, a clear distinction appears due to the strong configuration interaction, especially near the Cooper minimum. The n-resolved (n≤10) and total Maxwellian averaged rate coefficients are calculated, and the analytic fitting parameters are also provided. -- Highlights: ► The RR cross sections of Ar18+, Ar13+, Ar7+ and Ar+ are obtained. ► The Kramer formula, the relativistic self-consistent field and RCI methods are used. ► Results from three methods are compared with each other.

  9. Electronics calibration board for the ATLAS liquid argon calorimeters

    International Nuclear Information System (INIS)

    To calibrate the energy response of the ATLAS liquid argon calorimeter, an electronics calibration board has been designed; it delivers a signal whose shape is close to the calorimeter ionization current signal with amplitude up to 100 mA in 50 Ω with 16 bit dynamic range. The amplitude of this signal is designed to be uniform over all calorimeters channels, stable in time and with an integral linearity much better that the electronics readout. The various R and D phases and most of the difficulties met are discussed and illustrated by many measurements. The custom design circuits are described and the layout of the ATLAS calibration board presented. The procedure used to qualify the boards is explained and the performance obtained illustrated: a dynamic range up to 3 TeV in three energy scales with an integral linearity better than 0.1% in each of them, a response uniformity better than 0.2% and a stability better than 0.1%. The performance of the board is well within the ATLAS requirements. Finally, in situ measurements done on the ATLAS calorimeter are shown to validate these performances

  10. Methane from benzene in argon dielectric barrier discharge

    International Nuclear Information System (INIS)

    Highlights: ► Efficient on-line conversion of benzene to methane at room temperature. ► Absence of other H-atom donor suggests new type of chemistry. ► For parent loss > 90%, methane yield was ∼40% of limit due to H-atom availability. ► Surface moisture contributed ·OH radical for trace phenolic products’ formation. ► This method may emerge as an exploitable tactic for pollutants’ usable alterations. -- Abstract: A first-time account of direct, on-line, instantaneous and efficient chemical conversion of gas phase benzene to methane in argon Dielectric Barrier Discharge (DBD) is presented. In the absence of another overt hydrogen-donating source, potency of analogous parents toward methane generation is found to follow the order: benzene > toluene > p-xylene. Simultaneous production of trace amounts of phenolic surface deposits suggest (a) prompt decomposition of the parent molecules, including a large fraction yielding atomic transients (H-atom), (b) continuous and appropriate recombination of such parts, and (c) trace moisture in parent contributing ·OH radicals and additional H-atoms, which suitably react with the unreacted fraction of the parent, and also other intermediates. Results highlight Ar DBD to be a simple and exploitable technology for transforming undesirable hazardous aromatics to usable/useful low molecular weight open-chain products following the principles of green chemistry and engineering

  11. Crack growth through the thickness of thin-sheet Hydrided Zircaloy-4

    Science.gov (United States)

    Raynaud, Patrick A. C.

    In recent years, the limits on fuel burnup have been increased to allow an increase in the amount of energy produced by a nuclear fuel assembly thus reducing waste volume and allowing greater capacity factors. As a result, it is paramount to ensure safety after longer reactor exposure times in the case of design-basis accidents, such as reactivity-initiated accidents (RIA). Previously proposed failure criteria do not directly address the particular cladding failure mechanism during a RIA, in which crack initiation in brittle outer-layers is immediately followed by crack growth through the thickness of the thin-wall tubing. In such a case, the fracture toughness of hydrided thin-wall cladding material must be known for the conditions of through-thickness crack growth in order to predict the failure of high-burnup cladding. The fracture toughness of hydrided Zircaloy-4 in the form of thin-sheet has been examined for the condition of through-thickness crack growth as a function of hydride content and distribution at 25°C, 300°C, and 375°C. To achieve this goal, an experimental procedure was developed in which a linear hydride blister formed across the width of a four-point bend specimen was used to inject a sharp crack that was subsequently extended by fatigue pre-cracking. The electrical potential drop method was used to monitor the crack length during fracture toughness testing, thus allowing for correlation of the load-displacement record with the crack length. Elastic-plastic fracture mechanics were used to interpret the experimental test results in terms of fracture toughness, and J-R crack growth resistance curves were generated. Finite element modeling was performed to adapt the classic theories of fracture mechanics applicable to thick-plate specimens to the case of through-thickness crack growth in thin-sheet materials, and to account for non-uniform crack fronts. Finally, the hydride microstructure was characterized in the vicinity of the crack tip by

  12. Optically Forbidden Excitations of 3s Electron of Argon by Fast Electron Impact

    Institute of Scientific and Technical Information of China (English)

    朱林繁; 成华东; 刘小井; 田鹏; 苑震生; 李文斌; 徐克尊

    2003-01-01

    The electron energy loss spectrum of argon in the energy region of 24.5-30.5eV was measured at 2.5 keV impact energy. The line profile parameters of the optically forbidden excitations of 3s-1ns (n = 4-6) and 3s-1nd (n = 3-7) of argon, I.e.,Eγ,Г,q and p,were determined.

  13. Benchmarking TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems

    OpenAIRE

    Baptista, B.; Bugel, L.; Chiu, C; Conrad, J. M.; Ignarra, C. M.; Jones, B. J. P.; Katori, T.; Mufson, S.

    2012-01-01

    Scintillation light from liquid argon is produced at 128 nm and thus must be shifted to visible wavelengths in light detection systems used for Liquid Argon Time Projection Chambers (LArTPCs). To date, designs have employed tetraphenyl butadiene (TPB) coatings on photomultiplier tubes (PMTs) or plates placed in front of the PMTs. Recently, a new approach using TPB-coated light guides was proposed. In this paper, we show that the response of lightguides coated with TPB in a UV Transmitting (UV...

  14. TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems

    CERN Document Server

    Ignarra, C M

    2013-01-01

    Light detection systems in Liquid Argon Time Projection Chambers (LArTPCs) require the detection of the 128 nm light produced during argon scintillation. Most detectors use Tetraphenyl Butadiene (TPB) to shift the wavelength of the light into a range visible to Photomultiplier Tubes (PMTs). These proceedings summarize characterizations of light-guides coated with a matrix of TPB in UV transmitting acrylic which are more compact than existing LArTPC light collection systems.

  15. TPB-coated light guides for liquid argon TPC light detection systems

    Science.gov (United States)

    Ignarra, C. M.

    2013-10-01

    Light detection systems in Liquid Argon Time Projection Chambers (LArTPCs) require the detection of the 128 nm light produced during argon scintillation. Most detectors use Tetraphenyl Butadiene (TPB) to shift the wavelength of the light into a range visible to Photomultiplier Tubes (PMTs). These proceedings summarize characterizations of light-guides coated with a matrix of TPB in UV transmitting acrylic which are more compact than existing LArTPC light collection systems.

  16. Effect of Ginkgo biloba on the lesions induced by retinal argon laser photocoagulation in rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Clairambault, P.; Pairault, C.; Droy-Lefaix, M.T.; Magnier, B.; Magnier, M.

    1986-01-09

    In rabbits, retinal argon laser photocoagulation disrupts the arrangement of cell layers and produces interstitial edema. Photochemical and thermal energy is released with production of free oxygenated radicals that are responsible for destruction of cell membranes. Retinal argon laser photocoagulation in rabbits was used as a pharmacologic model to evaluate the protective effect of EGB 761 against membrane lesions and edema. As a strong free radicals scavengers, EGB 761 confirms its protective action on cells membranes and its anti-edema effect.

  17. Configurational Entropy,Diffusivity and Potential Energy Landscape in Liquid Argon

    Institute of Scientific and Technical Information of China (English)

    DUAN Yong-Ping; MA Cong-Xiao; LI Jia-Yun; LI Cong; WANG Dan; LI Mei-Li; SUN Min-Hua

    2009-01-01

    The configurational entropy, diffusion coefficient, dynamics and thermodynamics fragility indices of liquid argon are calculated using molecular dynamics simulations at two densities. The relationship between dynamics and thermodynamics properties is studied. The diffusion coefficient depends linearly on configurational entropy, which is consistent with the hypothesis of Adam-Gibbs. The consistence of dynamics and thermodynamics fragility indices demonstrates that dynamical behaviour is governed by thermodynamics behaviour in glass transition of liquid argon.

  18. Effect of Ginkgo biloba on the lesions induced by retinal argon laser photocoagulation in rabbits

    International Nuclear Information System (INIS)

    In rabbits, retinal argon laser photocoagulation disrupts the arrangement of cell layers and produces interstitial edema. Photochemical and thermal energy is released with production of free oxygenated radicals that are responsible for destruction of cell membranes. Retinal argon laser photocoagulation in rabbits was used as a pharmacologic model to evaluate the protective effect of EGB 761 against membrane lesions and edema. As a strong free radicals scavengers, EGB 761 confirms its protective action on cells membranes and its anti-edema effect

  19. A correction to Birks' Law in liquid argon ionization chamber simulations for highly ionizing particles

    International Nuclear Information System (INIS)

    We present a study of the performance of Birks' Law in liquid argon ionization chamber simulations as applied to highly ionizing particles, such as particles with multiple electric charges or with magnetic charge. We used Birks' Law to model recombination effects in a GEANT4 simulation of heavy ions in a liquid argon calorimeter. We then compared the simulation to published heavy-ion data to extract a highly ionizing particle correction to Birks' Law.

  20. LArGe: Background suppression using liquid argon (LAr) scintillation for 0$\

    CERN Document Server

    Marco, M D; Schönert, S

    2007-01-01

    Measurements with a bare p-type high purity germanium diode (HPGe) submerged in a 19 kg liquid argon (LAr) scintillation detector at MPIK Heidelberg are reported. The liquid argon--germanium system (LArGe) is operated as a 4$\\pi$ anti-Compton spectrometer to suppress backgrounds in the HPGe. This R&D is carried out in the framework of the GERDA experiment which searches for 0$\

  1. Hydrophilic pyrazine-based phosphane ligands: synthesis and application in asymmetric hydride transfer and H2-hydrogenation of acetophenone

    NARCIS (Netherlands)

    Nikishkin, N.; Huskens, J.; Verboom, W.

    2013-01-01

    Pyrazine-based hydrophilic phosphanes are useful ligands for the ruthenium- and rhodium-catalyzed hydrogenations of acetophenone under hydride transfer and dihydrogen conditions. The effect of alcohol additives on the catalytic, enantioselective aqueous hydrogenation of acetophenone is examined with

  2. Direct determination of Ge in hot spring waters and coal fly ash samples by hydride generation-ETAAS

    Energy Technology Data Exchange (ETDEWEB)

    Moscoso-Perez, Carmen; Moreda-Pineiro, Jorge; Lopez-Mahia, Purificacion; Muniategui-Lorenzo, Soledad; Fernandez-Fernandez, Esther; Prada-Rodriguez, Dario [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira, s/n. E-15071, A Coruna (Spain)

    2004-10-08

    A method for Ge determination in hot spring water and acid extracts from coal fly ash samples involving hydride generation, trapping and atomisation of the hydride generated from Ir-treated graphite tubes (GTs) has been developed. Hydride was generated from hydrochloric acid medium using sodium tetrahydroborate. Several factors affecting the hydride generation, transport, trapping and atomisation efficiency were studied by using a Plackett-Burman design. Results obtained from Plackett-Burman designs suggest that trapping and atomisation temperatures are the significant factors involved on the procedure. The accuracy was studied using NIST-1633a (coal fly ash) reference material. The detection limit of the proposed method was 2.4{mu}gl{sup -1} and the characteristic mass of 233pg was achieved. The Ge concentrations in fly ash and hot spring samples were between 6.25-132{mu}gg{sup -1} and 12.84-36.2{mu}gl{sup -1}.

  3. Poisoning Experiments Aimed at Discriminating Active and Less-Active Sites of Silica-Supported Tantalum Hydride for Alkane Metathesis

    KAUST Repository

    Saggio, Guillaume

    2010-10-04

    Only 50% of the silica-supported tantalum hydride sites are active in the metathesis of propane. Indeed, more than 45% of the tantalum hydride can be eliminated by a selective oxygen poisoning of inactive sites with no significant decrease in the global turnover. Conversely, cyclopentane induces no such selective poisoning. Hence, the active tantalum hydride sites that show greater resistance to oxygen poisoning correspond to the νTa-H bands of higher wavenumbers, particularly that at 1860cm-1. These active tantalum hydride sites should correspond to tris- or monohydride species relatively far from silica surface oxygen atoms. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Discovery of photospheric argon in very hot central stars of planetary nebulae and white dwarfs

    CERN Document Server

    Werner, K; Kruk, J W

    2007-01-01

    We report the first discovery of argon in hot evolved stars and white dwarfs. We have identified the ArVII 1063.55A line in some of the hottest known (Teff=95000-110000 K) central stars of planetary nebulae and (pre-) white dwarfs of various spectral type. We determine the argon abundance and compare it to theoretical predictions from stellar evolution theory as well as from diffusion calculations. We analyze high-resolution spectra taken with the Far Ultraviolet Spectroscopic Explorer. We use non-LTE line-blanketed model atmospheres and perform line-formation calculations to compute synthetic argon line profiles. We find a solar argon abundance in the H-rich central star NGC1360 and in the H-deficient PG1159 star PG1424+535. This confirms stellar evolution modeling that predicts that the argon abundance remains almost unaffected by nucleosynthesis. For the DAO-type central star NGC7293 and the hot DA white dwarfs PG0948+534 and REJ1738+669 we find argon abundances that are up to three orders of magnitude sma...

  5. Numerical study of breakdown pattern induced by an intense microwave under nitrogen and argon gases

    Science.gov (United States)

    Takahashi, Masayuki; Ohnishi, Naofumi

    2016-07-01

    Filamentary plasma induced by microwave beam irradiation was reproduced in nitrogen and argon by combining fluid or particle plasma models with electromagnetic wave propagation. Transport coefficients used in the fluid model are estimated from particle simulation to maintain consistency of the breakdown structure between the fluid and particle models. A discrete structure was obtained using the one-dimensional (1D) fluid model, because a standing wave is generated in front of the plasma when the incident microwave beam is reflected by the overcritical plasma, which agrees with the breakdown structure obtained using the 1D particle model. A 2D plasma filament was also reproduced using the fluid model in nitrogen and argon. Reflection of the incident microwave in argon becomes stronger than that in nitrogen because of the denser argon plasma. Change in filament shape is induced in argon because the electric field is deformed at the plasma tip owing to stronger wave reflection from the neighboring filament. The propagation speed of the plasma front becomes larger in argon breakdown because of the larger ionization frequency and the larger diffusion coefficient.

  6. Condensed argon isentropic compression with ultrahigh magnetic field pressure: Experimental design. Post-shot report

    Energy Technology Data Exchange (ETDEWEB)

    Bykov, A.I.; Boriskov, G.V.; Dolotenko, M.I. [All-Russian Research Inst. of Experimental Physics, Sarov (Russian Federation)] [and others

    1996-12-31

    This report continues the series of work devoted to experimental study of a high-dense condensed argon state. Remember that according to work of Kwon et. al., hexagonal close-packed structure is profitable in terms of energy rather than face-centered argon structure (stable with zero pressure). What is most interesting and intriguing here is the issue of possible argon metallization, when it is compressed up to the densities more than 9.17 g/cm{sup 3}. In the experiment of 1995 (the arrangement and data are described in a cited reference) the authors recorded appearance of conductivity in argon, which is non-conductive in the initial state, when it is compressed more than a factor of four. The peak value of argon specific conductivity recorded in this experiment did not exceed 10 (Ohm x cm){sup {minus}1}. This value of conductivity is characteristic of semiconductors, but not metals, which have 10{sup 4} (Ohm x cm){sup {minus}1}. At this stage of the work the main attention is paid to recording of argon conductive state and studying the possibilities of multiframed radiography of the sample in the compressed state.

  7. Low radioactivity argon dark matter search results from the DarkSide-50 experiment

    CERN Document Server

    Agnes, P; Albuquerque, I F M; Alexander, T; Alton, A K; Arisaka, K; Back, H O; Baldin, B; Biery, K; Bonfini, G; Bossa, M; Bottino, B; Brigatti, A; Brodsky, J; Budano, F; Bussino, S; Cadeddu, M; Cadonati, L; Cadoni, M; Calaprice, F; Canci, N; Candela, A; Cao, H; Cariello, M; Carlini, M; Catalanotti, S; Cavalcante, P; Chepurnov, A; Cocco, A G; Covone, G; Crippa, L; D'Angelo, D; D'Incecco, M; Davini, S; De Cecco, S; De Deo, M; De Vincenzi, M; Derbin, A; Devoto, 25 A; Di Eusanio, F; Di Pietro, G; Edkins, E; Empl, A; Fan, A; Fiorillo, G; Fomenko, K; Forster, G; Franco, D; Gabriele, F; Galbiati, C; Giganti, C; Goretti, A M; Granato, F; Grandi, L; Gromov, M; Guan, M; Guardincerri, Y; Hackett, B R; Herner, K; Hungerford, E V; Ianni, Al; Ianni, An; James, I; Jollet, C; Keeter, K; Kendziora, C L; Kobychev, V; Koh, G; Korablev, D; Korga, G; Kubankin, A; Li, X; Lissia, M; Lombardi, P; Luitz, S; Ma, Y; Machulin, I N; Mandarano, A; Mari, S M; Maricic, J; Marini, L; Martoff, C J; Meregaglia, A; Meyers, P D; Miletic, T; Milincic, R; Montanari, D; Monte, A; Montuschi, M; Monzani, M; Mosteiro, P; Mount, B J; Muratova, V N; Musico, P; Napolitano, J; Nelson, A; Odrowski, S; Orsini, M; Ortica, F; Pagani, L; Pallavicini, M; Pantic, E; Parmeggiano, S; Pelczar, K; Pelliccia, N; Perasso, S; Pocar, A; Pordes, S; Pugachev, D A; Qian, H; Randle, K; Ranucci, G; Razeto, A; Reinhold, B; Renshaw, A L; Romani, A; Rossi, B; Rossi, N; Rountree, D; Sablone, D; Saggese, P; Saldanha, R; Sands, W; Sangiorgio, S; Savarese, C; Segreto, E; Semenov, D A; Shields, E; Singh, P N; Skorokhvatov, M D; Smallcomb, M; Smirnov, O; Sotnikov, A; Stanford, C; Suvorov, Y; Tartaglia, R; Tatarowicz, J; Testera, G; Tonazzo, A; Trinchese, P; Unzhakov, E V; Vishneva, A; Vogelaar, B; Wada, M; Walker, S; Wang, H; Wang, Y; Watson, A W; Westerdale, S; Wilhelmi, J; Wojcik, M M; Xiang, X; Xu, J; Yang, C; Yoo, J; Zavatarelli, S; Zec, A; Zhong, W; Zhu, C; Zuzel, G

    2015-01-01

    The DarkSide-50 dark matter search reports the first results obtained using a target of low-radioactivity argon extracted from underground sources. The experiment is located at the Laboratori Nazionali del Gran Sasso and uses a two-phase time projection chamber as a detector. A total of 155 kg of low radioactivity argon has been obtained, and we have determined that underground argon is depleted in Ar-39 by a factor (1.4 +- 0.2) x 10^3 relative to atmospheric argon. The underground argon was also found to contain (2.05 +- 0.13) mBq/kg of Kr-85. We found no evidence for dark matter in the form of WIMPs in 70.9 live-days of data with a fiducial mass of (36.9 +- 0.6) kg. When combined with our preceding search with an atmospheric argon target, we set a 90 % C.L. upper limit on the WIMP-nucleon spin-independent cross section of 2.0 x 10^-44 cm^2 (8.6 x 10^-44 cm^2, 8.0 x 10^-43 cm^2 ) for a WIMP mass of 100 GeV/c^2 (1 TeV/c^2 , 10 TeV/c^2 ).

  8. Results from the first use of low radioactivity argon in a dark matter search

    Energy Technology Data Exchange (ETDEWEB)

    Agnes, P. [Universite Paris Diderot (France). et al.

    2016-04-08

    Liquid argon is a bright scintillator with potent particle identification properties, making it an attractive target for direct-detection dark matter searches. The DarkSide-50 dark matter search here reports the first WIMP search results obtained using a target of low-radioactivity argon. DarkSide-50 is a dark matter detector, using two-phase liquid argon time projection chamber, located at the Laboratori Nazionali del Gran Sasso. The underground argon is shown to contain Ar-39 at a level reduced by a factor (1.4 +- 0.2) x 103 relative to atmospheric argon. We report a background-free null result from (2616 +- 43) kg d of data, accumulated over 70.9 live-days. When combined with our previous search using an atmospheric argon, the 90 % C.L. upper limit on the WIMP-nucleon spin-independent cross section based on zero events found in the WIMP search regions, is 2.0 x 10-44 cm2 (8.6 x 10-44 cm2, 8.0 x 10-43 cm2) for a WIMP mass of 100 GeV/c2 (1 TeV/c2 , 10 TeV/c2).

  9. Effects of Hydride Precipitation on the Stress Developed in ZrO2 Thin Film

    International Nuclear Information System (INIS)

    It has been reported that the effect of thermal redistribution of hydrides across the metal-oxide interface, coupled with thermal feedback on the metal-oxide interface, is a dominating factor in the accelerated oxidation in zirconium alloys cladding PWR fuel. Especially the precipitated and redistributed hydrides are known to relieve the stress imposed onto the metal/oxide interface during the waterside corrosion of zirconium alloys. Without the hydrides the stress exceeds the critical value of 3 GPa which induce the tetragonal ZrO2 phase formation. Therefore, in this study enhanced oxidation due to the precipitated hydrides are experimentally confirmed and stress on the interface is measured with steam beam apparatus in order to support hypothesis hydrides precipitates relieve the stress. In steam beam apparatus, Oxidation reaction occurs only the surface exposed to the steam beam. In order to avoid the oxidation of the other side of specimen, whole chamber is evacuated down to ultra-high vacuum (down to 10-5 Torr). The oxide thickness is measured with weight gain measurement and the curvature of the single side oxidized specimen is measured with spherometer. Specimen is thin film zirconium foil whose thickness is 40μm and diameter is 20mm. Only single surface of specimen exposed to the steam beam oxidizes at 400 .deg. C which is attained by halogen lamp. Basically the measurement technique used in this study is based on the curvature build-up during the single side oxidation process. The stress build-up can be directly evaluated according to the Stoney's formula. Measured stress from the curvature estimation are plotted as a function of thin oxide film thickness. And atmospheric oxidation was also carried out in the electric furnace using the specimen holder, which is designed to protect the other side oxidation of specimen. The stress in the oxide increases as the thickness decreases and the highest stress measured in this study is 5.2 GPa which is higher than

  10. Magnesium based metal hydride reactor incorporating helical coil heat exchanger: Simulation study and optimal design

    International Nuclear Information System (INIS)

    Highlights: • A new 3D modeling for Mg-based metal hydride reactor is proposed. • Hydriding kinetics of Mg-based alloys is modeled based on the experimental data. • Helical coil heat exchanger has better heat transfer effect than traditional one. • The reactor with smaller non-dimensional pitch has favorable performance. - Abstract: Magnesium based metal hydride has been viewed as one of the most commonly-used materials in the practical applications of hydrogen energy systems. The heat and mass transfer processes have significant effects on the hydrogen storage performance of magnesium based metal hydride reactors. Incorporating helical coil heat exchanger into the reactor could be an effective way to improve the performance of heat and mass transfer. In this work, a new three-dimensional model for magnesium based metal hydride reactor with helical coil heat exchanger is proposed and solved using the commercial software package COMSOL Multiphysics V3.5a. The comparison of hydrogen storage behaviors between the reactors incorporating the traditional straight pipe and new helical coil heat exchangers is firstly conducted based on the numerical simulation. The comparison results show that the helical coil heat exchanger has better effect on improving the characteristics of reactor than the straight pipe heat exchanger due to its secondary circulation. The effects of key parameters, including the initial conditions, heat transfer coefficients of heat transfer fluid and helical coil geometry on the characteristics of reactor with the helical coil heat exchanger are also analyzed systematically. It is discovered that larger initial hydrogen pressure and lower initial temperature are beneficial to the improvement of hydrogen absorption kinetics, because of the greater driving force for the hydriding reaction. The results of optimal design suggest that smaller non-dimensional pitch, the ratio of helical pitch to helical diameter, improves the heat and mass transfer

  11. Development of a direct hydride generation nebulizer for the determination of selenium by inductively coupled plasma optical emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Carrion, Nereida E-mail: ncarrion@strix.ciens.ucv.ve; Murillo, Miguel; Montiel, Edie; Diaz, Dorfe

    2003-08-15

    A study was conducted to evaluate the performance of a new direct hydride generation nebulizer system for determination of hydride forming elements by inductively coupled plasma optical emission spectroscopy. This system was designed and optimized to obtain the highest sensitivity. Several experimental designs were used for these purposes. To optimize the individual parameters of the system, and to study the interaction between these parameters for both direct hydride generation nebulizers, a central composite orthogonal design with eight factors was set up. Significant behavioral differences were observed in the two direct hydride generation nebulizers studied. Finally, a 70 {mu}m gas orifice nebulizer exhibits a better detection limit than the 120 {mu}m nebulizer. Generally, for determination of selenium, this new direct hydride generation nebulizer system exhibits a linear dynamic range and detection limit (3{sigma}b) of 3 orders of magnitude and 0.2 {mu}g l{sup -1} for selenium, respectively. This new hydride generator is much simpler system that conventional hydride generation systems, which does not need to be changed to work in normal mode with the inductively coupled plasma, since this system may be used for hydride forming elements and those that do not form them. It produces a rapid response with low memory effect. It reduces the interference level of Ni, Co and Cu to 600, 500 and 5 mg l{sup -1}, respectively. The accuracy of the system was verified by the determination of selenium in several standard reference materials of ambient, food and clinical sample matrices. No statistically significant differences (95 confidence level) were obtained between our method and the reference values.

  12. Angle-dependent hard X-ray photoemission study of Nb hydride formation in high-pressure supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Soda, Kazuo, E-mail: j45880a@cc.nagoya-u.ac.jp [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kondo, Hiroki; Yamaguchi, Kanta; Kato, Masahiko [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Shiraki, Tatsuhito; Niwa, Ken; Kusaba, Keiji; Hasegawa, Masashi [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Xeniya, Kozina; Ikenaga, Eiji [Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2015-09-15

    Highlights: • Nb hydrides in 10-GPa supercritical water are studied by photoelectron spectroscopy. • The hydride components of the Nb 3d core-level spectra are increased with the depth. • The bulk valence-band spectrum shows a split band due to the Nb–H bond formation. • The hydrides are formed in the bulk and their surfaces are covered with Nb oxides. - Abstract: Nb hydrides formation in 10-GPa supercritical water has been investigated by angle-dependent micro-beam hard X-ray photoemission spectroscopy. In the Nb 3d core-level spectra, Nb hydride components are found in the slightly high binding energy side of the metallic components, and the oxide ones are observed even though little oxides are recognized in X-ray diffraction patterns. Obtained emission-angle dependence of the Nb 3d core-level spectra of Nb hydride specimens shows that the Nb hydride components increase with the emission angle decreased i.e. the sampling depth increased, while the oxide ones decrease. The bulk valence-band spectrum is obtained by decomposing the measured valence-band spectra into a bulk and surface components with use of the emission-angle dependence of the core-level and valence-band spectra; it consists of two bands. This implies the Nb–H chemical bond formation and Nb in an oxidation state, consistent with reported band structure calculations and the observed core-level chemical shifts. Thus it is confirmed by valence-band and core-level photoelectron spectroscopy that the Nb hydrides are formed inside the specimen, irrespective to the well-known high oxidation ability of supercritical water.

  13. Structural and mechanical properties of alkali hydrides investigated by the first-principles calculations and principal component analysis

    Science.gov (United States)

    Settouti, Nadera; Aourag, Hafid

    2016-08-01

    The structural and mechanical properties of alkali hydrides (LiH, NaH, KH, RbH, and CsH) were investigated via first-principles calculations which cover the optimized structural parameters. The density functional theory in combination with the generalized gradient approximation (GGA) were used in this study. From the present study, one could note that alkali hydrides are brittle materials and mechanically stable. It was found that stiffness and shear resistance are greater in LiH than in other hydrides. It is more brittle in nature, and comparatively harder than the other materials under study; it also presents a high degree of anisotropy. The results were then investigated and analyzed with principal component analysis (PCA), which is one of the most common techniques in multivariate analysis, was used to explore the correlations among material properties of alkali hydrides and to study their trends. The alkali hydrides obtained by the first-principles calculations were also compared with the alkaline-earth metal hydrides (BeH2, MgH2, CaH2, SrH2, and BaH2) and discussed in this work.

  14. Study of hydride re orientation and mechanical property to evaluate spent fuel integrity during interim Dry storage

    International Nuclear Information System (INIS)

    The operating condition of modern PWRs is getting severer for the nuclear fuel cladding to meet the needs for an economical power generation. As the operating condition, oxide and the subsequent hydrogen caused by the waterside corrosion are generated in the cladding, which decreases the initial ductility of the cladding. Such an oxide and hydrogen act as a negative effect on the cladding safety under the Back End Fuel Cycle. In Korea, 23 nuclear power plants are in operation and lots of spent fuels are on the onsite storage. The onsite storage capacity in Korea is supposed to be full around at the year of 2016 and interim storage facilities could be considered to be constructed before 2016. Therefore, the dry storage concept is becoming a major technical consideration for intermediate spent fuel storage at present. In relation to this, studies on the effects of interim dry storage conditions to spent fuel integrity have recently been initiated in Korea. During the interim dry storage condition, the fuel cladding failure is affected by oxide thickness, hydride content and hydride re-orientation, among that the most important factor of the fuel cladding failure is the hydride reorientation, because the hydride reorientation behavior is shown by decrease cladding temperature in dry storage. however, the hydride reorientation mechanism was not clearly defined. To achieve this, it should be secured that the base technology for integrity assessment in dry storage. In this study, the hydride re orientation and its effect on the mechanical property of fuel cladding was studied

  15. Inhaled 45–50% argon augments hypothermic brain protection in a piglet model of perinatal asphyxia

    Science.gov (United States)

    Broad, Kevin D.; Fierens, Igor; Fleiss, Bobbi; Rocha-Ferreira, Eridan; Ezzati, Mojgan; Hassell, Jane; Alonso-Alconada, Daniel; Bainbridge, Alan; Kawano, Go; Ma, Daqing; Tachtsidis, Ilias; Gressens, Pierre; Golay, Xavier; Sanders, Robert D.; Robertson, Nicola J.

    2016-01-01

    Cooling to 33.5 °C in babies with neonatal encephalopathy significantly reduces death and disability, however additional therapies are needed to maximize brain protection. Following hypoxia–ischemia we assessed whether inhaled 45–50% Argon from 2–26 h augmented hypothermia neuroprotection in a neonatal piglet model, using MRS and aEEG, which predict outcome in babies with neonatal encephalopathy, and immunohistochemistry. Following cerebral hypoxia–ischemia, 20 Newborn male Large White piglets < 40 h were randomized to: (i) Cooling (33 °C) from 2–26 h (n = 10); or (ii) Cooling and inhaled 45–50% Argon (Cooling + Argon) from 2–26 h (n = 8). Whole-brain phosphorus-31 and regional proton MRS were acquired at baseline, 24 and 48 h after hypoxia–ischemia. EEG was monitored. At 48 h after hypoxia–ischemia, cell death (TUNEL) was evaluated over 7 brain regions. There were no differences in body weight, duration of hypoxia–ischemia or insult severity; throughout the study there were no differences in heart rate, arterial blood pressure, blood biochemistry and inotrope support. Two piglets in the Cooling + Argon group were excluded. Comparing Cooling + Argon with Cooling there was preservation of whole-brain MRS ATP and PCr/Pi at 48 h after hypoxia–ischemia (p < 0.001 for both) and lower 1H MRS lactate/N acetyl aspartate in white (p = 0.03 and 0.04) but not gray matter at 24 and 48 h. EEG background recovery was faster (p < 0.01) with Cooling + Argon. An overall difference between average cell-death of Cooling versus Cooling + Argon was observed (p < 0.01); estimated cells per mm2 were 23.9 points lower (95% C.I. 7.3–40.5) for the Cooling + Argon versus Cooling. Inhaled 45–50% Argon from 2–26 h augmented hypothermic protection at 48 h after hypoxia–ischemia shown by improved brain energy metabolism on MRS, faster EEG recovery and reduced cell death on TUNEL. Argon may provide a cheap and practical therapy

  16. Modelling steel’s homogenization during argon purging

    Directory of Open Access Journals (Sweden)

    J. Pieprzyca

    2012-12-01

    Full Text Available Purpose: One of the primary tasks that put the steel producers to the test is to reduce production costs while maintaining high quality. This objective is achieved among others through the optimization of conducted technological processes. Commonly used technology of steel homogenization with inert gases is an important stage in the production of steel in which that objective can be accomplished.Design/methodology/approach: Tests of hydrodynamic processes occurring during the steel blowing with inert gases process directly in industrial conditions is very difficult or impossible. Therefore, as the primary research method physical modelling was used. In order to carry out the tests described in the article a physical model of the station for the argon purging was used that is working at the VSB-TU, Department of Metallurgy and Foundry in Ostrava.Findings: As a result the study provided values for the investigated process and determined the appropriate location of the gas-permeable fittings in steelmaking ladle’s bottom plug. This allows to obtain the required conditions for the steel mixing in the entire volume of ladle’s workspace.Research limitations/implications: Tests presented in the article were carried out in the VSB-TU in Ostrava. Due to this fact some research limitations occurs that applies to localization and physical model’s specific construction. Therefore, as a result of cooperation between VSB-TU in Ostrava and the Silesian University of Technology will be carried out the construction of the new research station in Katowice.Practical implications: The results of the research constitute the basis to make changes that will allow the optimization to so far used purge of steel technology.Originality/value: The results presented in the article are addressed to the steel producers and it allows to optimize on-going steel homogenization process that takes place in the ladle

  17. Scintillation light from cosmic-ray muons in liquid argon

    Energy Technology Data Exchange (ETDEWEB)

    Whittington, Denver Wade [Indiana Univ., Bloomington, IN (United States). Physics Dept.; Mufson, S. [Indiana Univ., Bloomington, IN (United States). Astronomy Dept.; Howard, B. [Indiana Univ., Bloomington, IN (United States). Physics Dept.

    2016-05-01

    This paper reports the results of an experiment to directly measure the time-resolved scintillation signal from the passage of cosmic-ray muons through liquid argon. Scintillation light from these muons is of value to studies of weakly-interacting particles in neutrino experiments and dark matter searches. The experiment was carried out at the TallBo dewar facility at Fermilab using prototype light guide detectors and electronics developed for the Deep Underground Neutrino Experiment. Two models are presented for the time structure of the scintillation light, a phenomenological model and a physically-motivated model. Both models find tT = 1:52 ms for the decay time constant of the Ar 2 triplet state. These models also show that the identification of the “early” light fraction in the phenomenological model, FE 25% of the signal, with the total light from singlet decays is an underestimate. The total fraction of singlet light is FS 36%, where the increase over FE is from singlet light emitted by the wavelength shifter through processes with long decay constants. The models were further used to compute the experimental particle identification parameter Fprompt, the fraction of light coming in a short time window after the trigger compared with the light in the total recorded waveform. The models reproduce quite well the typical experimental value 0.3 found by dark matter and double b-decay experiments, which suggests this parameter provides a robust metric for discriminating electrons and muons from more heavily ionizing particles.

  18. Scintillation Light from Cosmic-Ray Muons in Liquid Argon

    Energy Technology Data Exchange (ETDEWEB)

    Whittington, Denver Wade [Indiana U.; Mufson, S. [Indiana U., Bloomington, Dept. Astron.; Howard, B. [Indiana U.

    2015-11-13

    This paper reports the results of an experiment to directly measure the time-resolved scintillation signal from the passage of cosmic-ray muons through liquid argon. Scintillation light from these muons is of value to studies of weakly-interacting particles in neutrino experiments and dark matter searches. The experiment was carried out at the TallBo dewar facility at Fermilab using prototype light guide detectors and electronics developed for the Deep Underground Neutrino Experiment. Two models are presented for the time structure of the scintillation light, a phenomenological model and a physically-motivated model. Both models find tT = 1:52 ms for the decay time constant of the Ar 2 triplet state. These models also show that the identification of the “early” light fraction in the phenomenological model, FE 25% of the signal, with the total light from singlet decays is an underestimate. The total fraction of singlet light is FS 36%, where the increase over FE is from singlet light emitted by the wavelength shifter through processes with long decay constants. The models were further used to compute the experimental particle identification parameter Fprompt, the fraction of light coming in a short time window after the trigger compared with the light in the total recorded waveform. The models reproduce quite well the typical experimental value 0.3 found by dark matter and double b-decay experiments, which suggests this parameter provides a robust metric for discriminating electrons and muons from more heavily ionizing particles.

  19. Scintillation light from cosmic-ray muons in liquid argon

    Science.gov (United States)

    Whittington, D.; Mufson, S.; Howard, B.

    2016-05-01

    This paper reports the results of an experiment to directly measure the time-resolved scintillation signal from the passage of cosmic-ray muons through liquid argon. Scintillation light from these muons is of value to studies of weakly-interacting particles in neutrino experiments and dark matter searches. The experiment was carried out at the TallBo dewar facility at Fermilab using prototype light guide detectors and electronics developed for the Deep Underground Neutrino Experiment. Two models are presented for the time structure of the scintillation light, a phenomenological model and a composite model. Both models find τT = 1.52 μs for the decay time constant of the Ar2* triplet state. These models also show that the identification of the ``early'' light fraction in the phenomenological model, FE ≈ 25% of the signal, with the total light from singlet decays is an underestimate. The total fraction of singlet light is FS ≈ 36%, where the increase over FE is from singlet light emitted by the wavelength shifter through processes with long decay constants. The models were further used to compute the experimental particle identification parameter Fprompt, the fraction of light coming in a short time window after the trigger compared with the light in the total recorded waveform. The models reproduce quite well the typical experimental value ~0.3 found by dark matter and double β-decay experiments, which suggests this parameter provides a robust metric for discriminating electrons and muons from more heavily ionizing particles.

  20. Size Controlled Synthesis of Germanium Nanocrystals: Effect of Ge Precursor and Hydride Reducing Agent

    Directory of Open Access Journals (Sweden)

    Darragh Carolan

    2015-01-01

    Full Text Available Germanium nanocrystals (Ge NCs have attracted increasing attention as a promising alternative to II–VI and IV–VI semiconductor materials as they are cheap, “green,” electrochemically stable, and compatible with existing CMOS processing methods. Germanium is a particularly attractive material for optoelectronic applications as it combines a narrow band gap with high carrier mobilities and a large exciton Bohr radius. Solution-phase synthesis and characterisation of size monodisperse alkyl-terminated Ge NCs are demonstrated. Ge NCs were synthesised under inert atmospheric conditions via the reduction of Ge halide salts (GeX4 by hydride reducing agents within inverse micelles. Regulation of NC size is achieved by variation of germanium precursor and the strength of hydride reducing agents used. UV-Visible absorbance and photoluminescence spectroscopy showed strong significant quantum confinement effects, with moderate absorption in the UV spectral range, and strong emission in the violet with a marked dependence on excitation wavelength.